Clinical Science (2003) 104, 47–63 (Printed in Great Britain)
R
E
V
I
E
W
Chemokines in the pathogenesis of liver
disease: so many players with
poorly defined roles
Kenneth J. SIMPSON*, Neil C. HENDERSON*, Cynthia L. BONE-LARSON†,
Nicholas W. LUKACS†, Cory M. HOGABOAM† and Steven L. KUNKEL†
*MRC Centre for Inflammation Research, University of Edinburgh, Edinburgh EH8 9AJ, U.K., and †Department of Pathology,
University of Michigan Medical School, Ann Arbor, MI, U.S.A.
A
B
S
T
R
A
C
T
Many new chemokines have been described in recent years, resulting in a new classification of
these chemoattractant proteins. The characterization of the biological functions of most
chemokines relates to their ability to induce chemotaxis in circulating inflammatory cells.
However, it is now clear that chemokines have a much wider biological role, including
angiogenesis, carcinogenesis and involvement in the pathogenesis of HIV infection. Our
understanding of the role of chemokines in the pathogenesis of disorders of the lungs and brain
outstrips that with regard to disorders of the liver. An increased understanding of the role of
chemokines in the pathogenesis of liver disease may lead to the development of novel therapies
for hepatic disease.
INTRODUCTION
Liver disease is increasing in incidence globally. Viral
hepatitis (particularly hepatitis B and C) represents a
massive healthcare burden which is set to increase in the
coming decades. An indicator of this trend is the recent
groundbreaking recommendation by the U.S. Advisory
Committee on Immunization Practices (AICP) that all
U.S. children be vaccinated against hepatitis B infection
at birth [1]. Cirrhosis is the eighth leading cause of death
by disease in the U.S.A. In the U.K., the cirrhosis
death rate rose in women from 5 per 100 000 deaths in
1994 to 6.7 in 1999, and in men from 7.3 to 10.9 per
100 000 over the same period. Cirrhosis of the liver now
kills more women than cervical cancer [2]. In the face of
this, the therapeutic repertoire for the treatment of liver
disease remains limited. Orthotopic liver transplantation
is the only effective treatment for severe liver failure, but
has several disadvantages, including limited donor liver
availability and the commitment of recipients to lifelong
toxic immunosuppression; in addition, patients can be
excluded from transplantation due to psychiatric or
medical contraindications. Hepatology has not so far
benefited from the synthesis of an effective artificial
organ, unlike mechanical ventilation in respiratory medicine or dialysis in renal failure. Indeed, recent studies to
Key words : chemokines, hepatic inflammation, liver injury.
Abbreviations : CCR, CC chemokine receptor ; CXCR, CXC chemokine receptor ; CINC, cytokine-induced neutrophil
chemoattractant ; CMV, cytomegalovirus ; mCMV, murine CMV ; ENA78, epithelial neutrophil-activating protein 78 ; GRO,
growth-related oncogene ; GVHD, graft-versus-host disease ; HCC, human CC chemokine ; IFN, interferon ; IL8 (etc.), interleukin
8 (etc.) ; IP10, interferon γ-inducible protein 10 ; I\R, ischaemia\reperfusion ; MCP, monocyte chemoattractant protein ; MIG,
monokine induced by interferon γ ; MIP, macrophage inflammatory protein ; p.f.u., plaque-forming units ; NK cell, natural killer cell ;
RANTES, regulated on T cell activation, normal T cell expressed and secreted ; SDF, stromal-derived factor ; TNFα, tumour necrosis
factor α.
Correspondence : Dr Kenneth J. Simpson (e-mail ksimp!srv1.med.ed.ac.uk).
# 2003 The Biochemical Society and the Medical Research Society
47
48
K. J. Simpson and others
develop an artificial liver have illuminated the fact that it
is likely that all cellular components and threedimensional structures (not only hepatocytes) of the liver
will have to be reconstituted in order to subserve
differentiated hepatic functions ex vivo. Effective alternative treatments to liver transplantation are urgently
required.
Common to many aetiologies of liver disease is an
inflammatory response. The key components of this
response are an expanding family of related chemotactic
cytokines now known as chemokines. Chemokines are
small-protein inflammatory mediators that were classically known for their elicitation of inflammatory cells
from the vasculature. However, contemporary studies
show that these ubiquitous factors impinge on many
facets of biology, including haematopoiesis, angiogenesis
and mitogenesis. Owing to their involvement in a
number of pathological processes, chemokines and their
receptors represent important therapeutic targets. Prevention of inflammatory cell recruitment by blockade of
the relevant chemokine receptor\ligand pair presents a
novel mode of therapy that can act upstream of the nonspecific anti-inflammatory therapies currently in use.
In addition, chemokine receptors are G-protein-coupled
seven-transmembrane receptors, which have proven to be
excellent pharmaceutical targets for many diseases [3].
Novel therapies including small-molecule chemokine
inhibitors, and virally encoded, recombinant and genetically engineered chemokines, are emerging rapidly. For
example, the number of small-molecule inhibitors of
chemokine receptors is growing in the patent literature,
and reports both in the literature as well as at conferences
in the field have shown these inhibitors to be effective in
inflammatory disease models, as well as inhibiting HIV1 infection and spread [3].
At present, chemokines are separated into four distinct
structurally and functionally related families according to
the relative positioning of the two cysteine residues at
their N-terminus [4,5]. The CC chemokine family have
two juxapositioned cysteine residues, and include the
monocyte chemoattractant proteins (MCP1–MCP5),
eotaxin, RANTES (regulated on T cell activation, normal
T cell expressed and secreted) and macrophage inflammatory proteins (MIPs). In general, the CC family is
chemotactic for mononuclear cells. The CXC chemokine
family is characterized by the presence of a nonconserved single amino acid (X ) between the two Nterminal cysteines. The CXC family is further subdivided
into ELR-positive and ELR-negative CXC chemokines.
The ELR chemokines have a three-amino-acid motif,
comprising glutamine (E), leucine (L) and arginine (R),
immediately adjacent to the CXC motif. The ELR CXC
chemokines include interleukin 8 (IL8), cytokineinduced neutrophil chemoattractant (CINC), MIP2,
epithelial neutrophil-activating protein 78 (ENA78),
growth-related oncogene α (GROα), GROβ, GROγ and
# 2003 The Biochemical Society and the Medical Research Society
Table 1 Human chemokine receptors and their associated
ligands
See the text for details.
Receptor
Ligands
CXCR1
CXCR2
CXCR3
CXCR4
CXCR5
CXCR6
CXCL8, CXCL6
CXCL1, CXCL2, CXCL3, CXCL5, CXCL6, CXCL7, CXCL8
CXCL9, CXCL10, CXCL11, CXCL13
CXCL12
CXCL13
CXCL15
CCR1
CCR2
CCR3
CCR4
CCR5
CCR6
CCR7
CCR8
CCR9
CCR10
CCR11
CCL3, CCL5, CCL7, CCL8, CCL14, CCL15, CCL16, CCL23
CCL2, CCL7, CCL8, CCL13, CCL16
CCL5, CCL7, CCL8, CCL11, CCL13, CCL15, CCL24, CCL26
CCL17, CCL22
CCL3, CCL4, CCL5, CCL16
CCL20
CCL19, CCL21
CCL1, CCL16
CCL25
CCL7, CCL25, CCL27, CCL28
CCL8, CCL13
CX3CR1
XCR1
CX3CL1
XCR1
KC (a murine homologue of GRO). The non-ELR CXC
chemokine family includes interferon-γ (IFNγ)-inducible
protein 10 (IP10) and monokine induced by IFNγ
(MIG). The ELR motif is important in chemokine ligand
binding. The ELR-positive chemokines can bind to CXC
chemokine receptor 1 (CXCR1) and\or CXCR2, while
the non-ELR chemokines bind CXCR3. Table 1 lists
human chemokine receptors and their associated ligands.
The ELR-positive CXC chemokines are important
neutrophil chemoattractants and induce angiogenesis. In
contrast, non-ELR CXC chemokines are chemotactic for
mononuclear cells and inhibit angiogenesis. The C and
CXC3C families of chemokines each contain only a
single member, lymphotactin and fractalkine (or neurotactin) respectively. Lymphotactin is a T cell chemotactic
factor. Fractalkine is a unique chemokine in both its
receptor and its structure, which contains a transmembrane glycoprotein and a chemokine domain at the
end of an extended mucin-like stalk. Fractalkine occurs in
both membrane-bound and soluble forms, and represents
a novel regulator of leucocyte chemotaxis and adhesion.
Originally, chemokines were isolated from stimulated
or unstimulated cultured cells and characterized on the
basis of their biological functions, mainly in relation to
their chemoattractant activity. More recently, screening
of cDNA libraries has been replaced by searching expressed sequence tag (EST ) databases for chemokine-like
sequences. These strategies to identify new chemokines,
along with the intense interest of the pharmaceutical
Chemokines in the pathogenesis of liver disease
industry in the light of the potential anti-HIV properties of chemokines, has led to an explosion in the
numbers of chemokines identified in both the CXC and
CC families. This led to a consensus conference to
produce a more rational nomenclature for all chemokines,
and this nomenclature is used throughout the present
review [6]. The increase in the numbers of chemokines
has also outstripped our understanding of their role in
pathological processes, particularly with regard to the
pathogenesis of liver disease. This review describes each
chemokine characterized (at the time of writing) and
discusses its known or potential role in the physiology
and\or pathophysiology of the liver.
CXC CHEMOKINES
CXCL1 (GROα), CXCL2 (GROβ) and CXCL3
(GROγ)
This sub-family of human chemokines was one of the
first to be characterized, along with the murine homologue of GRO (known as KC) and the rat homologue
(CINC). The GRO proteins are the products of three
separate genes. Both rodent and human chemokines bind
to a single receptor, CXCR2. CXCR2 and CXCL1,
CXCL2 and CXCL3 are widely distributed and are
expressed within the liver. Cellular expression occurs in
stimulated hepatocytes, macrophages (Kupffer cells),
activated stellate cells and endothelial cells [7–10].
Increased hepatic expression of GRO, KC or CINC has
been reported in a number of liver disorders. Hepatic
ischaemia\reperfusion (I\R), which may occur during
liver surgery or resuscitation following hypotension,
induces the hepatic expression of tumour necrosis factor
α (TNFα) and KC or CINC in the mouse and rat
respectively [11,12]. Immunoneutralization of KC or
inhibition of Kupffer cell function with gadolinium
chloride reduces both hepatic neutrophil infiltration and
liver injury. In mice, increased hepatic expression of KC
also occurs during sepsis, lipopolysaccharide injection,
hepatic infection and paracetamol poisoning [13–15].
Increases in hepatic CINC levels have also been reported
with similar experimental manipulations in rats [16,17].
In humans, hepatic expression of GRO occurs in disorders particularly associated with neutrophil infiltration, such as alcoholic hepatitis [18], although increases
also occur in other disorders [19].
However, the relationship between increased hepatic
GRO\KC\CINC expression, hepatic polymorphonuclear neutrophil leucocyte infiltration and hepatic
injury is complex. Administration of 10"! plaqueforming units (p.f.u.) of recombinant adenovirus containing CINC cDNA to rats increased hepatic and
circulating CINC concentrations and neutrophil counts,
and induced severe hepatic injury with inflammation,
compared with a control group administered an adenovirus containing luciferase [20]. However, the control
adenovirus also caused a significant increase in hepatic
neutrophilia compared with saline-treated controls. This
increase in neutrophils was associated with histological
and biochemical hepatic injury in the control adenovirustreated group, but hepatic CINC levels were similar to
those in saline-treated controls. Immunoneutralization
of KC in a sepsis model did not reduce hepatic neutrophil
infiltration, but decreased liver injury [13]. Alternatively,
murine hepatic I\R is associated with increased KC
expression, and chemokine inhibition is associated with
reduced neutrophil influx and hepatocellular injury [21].
Neutralization of CINC in a rat sepsis model also
decreased neutrophil influx into the liver and reduced
injury [22]. These conflicting data with regard to the
significance of increased levels of GRO\KC\CINC may
relate to the redundancy of the chemokine system.
Increases in other CXC chemokines, such as CXCL8
(IL8\MIP2) and CXCL6 (ENA78), commonly accompany increases in hepatic GRO\KC\CINC levels.
Others have shown that intravenous injection of KC led
to minor activation of peripheral blood neutrophils and
sinusoidal neutrophil sequestration compared with intravenous MIP2 [23]. The latter chemokine is also a more
potent neutrophil chemoattractant than KC. Alternatively, the mode of hepatic injury may dictate the
response to neutralization of GRO\KC\CINC. A recent
paper reported increased hepatic expression of KC (and
MIP2) in vivo following Fas-mediated apoptosis, which
was accompanied by hepatic neutrophil infiltration, thus
linking apoptosis with an inflammatory response [24].
Although inhibition of KC lowered hepatic neutrophil
influx, liver injury, as assessed by histology and circulating transaminases, was similar to that in controls.
These data suggest that liver injury induced by Fasmediated apoptosis may result in hepatic inflammation,
but the severe forms of liver injury reported in this
model proceed independently of increased hepatic
GRO\KC\CINC levels and neutrophil numbers. Lastly,
the levels of KC\CINC induced by a stimulus, both
in the liver and systemically, and the subsequent degree
of neutrophil accumulation and activation may affect the
response to immunoneutralization (see CXCL8 below).
CXCL5 (ENA78)
CXCL5 (ENA78) was first isolated from the conditioned
media of IL1β- or TNFα-treated epithelial cells. CXCL5
has a high degree of identity with other CXC chemokines, and its mRNA has been located within the liver.
Following appropriate stimuli, human hepatocytes, endothelial cells and macrophages (Kupffer cells) can express
CXCL5 [7]. This chemokine acts by binding to CXCR2,
which is also expressed on hepatocytes. Hepatic CXCL5
expression is increased in experimental alcoholic liver
# 2003 The Biochemical Society and the Medical Research Society
49
50
K. J. Simpson and others
disease and is correlated with the degree of necroinflammatory change. TNFα induces hepatic CXCL5
expression in both the ischaemic and non-ischaemic liver
lobes following I\R in rats [25]. IFNγ abrogates this
increase in CXCL5 concentration [26]. This effect of
IFNγ on the hepatic CXCL5 concentration was not
associated with any significant reduction in neutrophil
infiltration in either liver lobe following I\R, but did
reduce the severity of liver injury, as assessed by serum
aminotransferases. However, immunoneutralization of
CXCL5 reduces both hepatic neutrophil influx and liver
injury. Other studies have revealed that systemic release
of TNFα from the liver following hepatic I\R results in
neutrophil-mediated lung injury that is dependent on
TNFα-induced CXCL5 expression [27]. CXCL5 may
also have a permissive effect on hepatic regeneration.
CXCL5 expression is increased in rodent liver following
partial hepatectomy. Immunoneutralization of CXCL5
decreased the rate of hepatic regeneration, but did not
affect the recruitment of neutrophils seen in this model.
Furthermore, CXCL5 induces the proliferation of primary rodent hepatocytes in vitro [28].
CXCL8 (IL8) and MIP2
CXCL8 (IL8) was one of the first chemokines to be
identified and characterized. Reflecting its biological
activity, IL8 had several different names before being rechristened CXCL8. Many different cells produce this
chemokine following appropriate stimuli. Exposure of
hepatocytes to stimuli such as oxidative stress, ethanol,
IL1β and TNFα results in the production of CXCL8 [7].
This chemokine can also be produced by endothelial
cells, Kupffer cells, biliary epithelial cells and stellate cells
[29–31]. The biological effects of CXCL8 are mediated
by its binding to CXCR1 and CXCR2. No mouse
homologue has been described, but human CXCL8 most
closely resembles murine MIP2 and rat CINC. For the
purposes of this review the biological effects of MIP2 will
be discussed along with those of IL8 (CXCL8).
Many studies have measured circulating chemokine
concentrations in patients with liver disease. CXCL8 is
perhaps the best studied. The highest concentrations are
reported in patients with alcoholic hepatitis, with lower
concentrations associated with other histological forms
of alcoholic liver disease [32,33]. Circulating CXCL8 is
also increased in patients with viral hepatitis or acute
graft-versus-host disease (GVHD), and following liver
transplantation [34–36]. In general, increased levels of
CXCL8 correlate with reduced survival and impaired
hepatic function, and arise from increased production
and\or reduced hepatic clearance. We have found levels
of CXCL8 to be significantly higher in hepatic venous
than in portal venous blood, implying increased hepatic
production in patients with chronic alcoholic liver
disease.
# 2003 The Biochemical Society and the Medical Research Society
The pathophysiological significance of these increased
circulating CXCL8 concentrations is not clear. In murine
studies, increased hepatic neutrophil accumulation occurs
in CXCL8 transgenic mice and following systemic
administration of high doses of MIP2 [23,37]. However,
the latter study did not find any infiltration of neutrophils
into the hepatic parenchyma, and concluded that
increased circulating chemokine concentrations may
direct neutrophils towards, but not into, liver tissue.
Previous studies using non-specific chemoattractants
have shown reduced neutrophil chemotaxis in patients
with liver cirrhosis, especially alcoholic cirrhosis [58,59].
This defect was partly due to a circulating inhibitor of
neutrophil chemotaxis [38,39]. Using a modified Boyden
chamber technique, we found reduced neutrophil chemotaxis in response to CXCL8 (and CXCL1) in patients
with liver disorders, including alcoholic cirrhosis and
acute liver failure [40]. This defective chemotaxis may
partly explain the high risk of infection in these patients.
The defective IL8-induced chemotaxis is worse following
simulated gastrointestinal haemorrhage and improves
after liver transplantation [41]. Despite the increased
circulating CXC chemokine concentrations associated
with these conditions, expression of CXCR1 and
CXCR2 in neutrophils was normal [42]. These data
suggest that the defect in neutrophil chemotaxis in
response to CXC chemokines in patients with liver
failure is due to abnormal chemokine–chemokine-receptor interactions and\or post-receptor signalling abnormalities.
CXCL8 (like other chemokines) is expressed in the
hepatic parenchyma at sites of inflammation during
alcoholic hepatitis, and correlates with the neutrophilic
infiltration characteristic of this form of liver injury. In
alcoholic cirrhosis the expression of CXCL8 was more
restricted to inflammatory cells and endothelium in
fibrous septa and portal tracts [43]. Experimental models
of alcoholic liver disease also reveal increased plasma and
hepatic MIP2 concentrations, which also correlate with
the extent of necro-inflammatory changes in the liver
[44]. Isolated Kupffer cells from alcohol-fed rats spontaneously produced 4-fold more MIP2 than those from
pair-fed controls, suggesting that Kupffer cells are a
major source of MIP2 in this model [45]. In addition to
the potential for recruiting neutrophils, MIP2 was also
directly toxic to hepatocytes prepared from chronic
alcohol-fed animals. This effect could be blocked cycloheximide, implicating protein synthesis in the hepatotoxic effects of MIP2 [45]. In a sepsis model induced by
caecal ligation and puncture, the expression of CXC
chemokines, including MIP2, is dramatically upregulated in the liver [14]. Increased hepatic MIP2
concentrations also arise from enhanced Kupffer cell
production, as shown by the decrease following gadolinium chloride administration. Immunoneutralization
of MIP2 decreased neutrophil influx into the liver,
Chemokines in the pathogenesis of liver disease
reduced hepatic injury and improved survival following
caecal ligation and puncture [14].
Systemic adenoviral gene therapy is associated with
severe acute hepatocellular injury. Chemokines, including MIP2, play important roles in both mediating and
mitigating this injury, related in part to their relative
abundance in the liver and their intended cellular
targets. For example, in mice given a dose of 10"!
p.f.u. of a control recombinant adenovirus containing
β-galactosidase or green fluorescent protein, significant
increases in hepatic MIP2 concentrations and neutrophil
numbers in the liver were noted [20]. This control adenovirus also caused a 4-fold increase in hepatic neutrophil
influx and increased serum transaminases compared with
saline-injected controls, indicating that the adenovirus
vector alone causes liver injury, presumably via stimulating neutrophil influx. Other studies have suggested
that overexpression of ELR CXC chemokines in gene
targeting may be beneficial [46]. In mice receiving the
lower dose of 10) p.f.u. of adenovirus containing rat
MIP2 cDNA, hepatic injury was markedly lower than in
mice that received an empty cassette. The lack of liver
injury was further illustrated when the adeno-MIP2treated group was challenged with paracetamol. The
adeno-MIP2 treatment protected the mice from
paracetamol-induced injury and, surprisingly, caused a
decrease in neutrophil infiltration and an increase in
hepatocyte proliferation. In the latter model of hepatic
failure, paracetamol administration alone increased liver
concentrations of MIP2, and inhibiting hepatic MIP2
expression increased liver injury and mortality [47].
These data suggest two contrasting effects of CXC
chemokines in modulating hepatic injury and repair,
related to the relative concentrations of the chemokines
and the target cells within the liver. Very high concentrations of CXC chemokines increase peripheral leucocyte recruitment to the liver. In contrast, lower
concentrations of CXC chemokines are hepatoprotective
and fail to induce hepatic neutrophilia. Cadmium
poisoning also induces acute severe hepatocellular injury.
In contrast with our findings with paracetamol poisoning,
mortality in CXCL8 transgenic mice was increased
following acute cadmium exposure. Surprisingly, the
increased mortality was associated with reduced hepatic
neutrophil infiltration [48].
These novel hepatoprotective effects of CXC chemokines, such as CXCL8, may be related in part to their
ability to stimulate hepatocyte proliferation [28]. CXCL8
functions as an autocrine growth factor for human
hepatoma cell lines. CXCL8 and other CXC chemokines,
including CXCL5 and MIP2, also stimulate primary
rodent hepatocyte proliferation in vitro. Like other
biological responses, these mitogenic effects of CXCL8
(and other CXC chemokines such as CXCL5) are
inhibited by the ELR-negative chemokines CXCL9 and
CXCL10 [28]. Using a rat partial hepatectomy model to
study hepatocyte proliferation in vivo, MIP2 and
CXCL5 concentrations were up-regulated, and immunoneutralization of these chemokines delayed hepatic regeneration, an effect that occurred without influencing
hepatic neutrophil recruitment [28].
MIP2 has also been implicated in the response of the
liver to I\R. TNFα up-regulates the hepatic expression of
vascular endothelial cell adhesion molecules and of CXC
chemokines such as MIP2 in this model [21]. Immunoneutralization of MIP2 led to a decrease in hepatic
neutrophil influx and injury. Furthermore, treatment
with anti-inflammatory cytokines, such as IL10 or IL13,
resulted in decreased TNFα and MIP2 levels, which were
associated with decreases in neutrophil accumulation
and hepatic injury [49,50]. The mode of action of
IL10 and IL13 appears to depend on a decrease in nuclear
factor κB and increased STAT6 (signal transducer and
activator of transcription 6) activation respectively. Thus
manipulation of chemokine levels may provide important
prophylactic treatment in liver surgery that may lead to
I\R injury.
Injection of concanavalin A induces non-specific T cell
activation, with production of TNFα and IFNγ and
immune-mediated liver injury. A recent study found
increased plasma MIP2 levels (but did not measure
hepatic concentrations) following concanavalin A injection, associated with neutrophil influx into the liver;
immunoneutralization of MIP2 was partially protective,
with an approx. 50 % reduction in plasma transaminases
[51]. This protective effect was also associated with a
partial decrease in hepatic neutrophil influx. Presumably
other CXC chemokines and CC chemokines are induced
in this model, and are important in mediating both
neutrophil and lymphocyte influx into the liver.
CXCL9 (MIG)
CXCL9 is produced by monocytes\macrophages,
neutrophils and other inflammatory cells, and by stromal
cells such as hepatocytes, following either stimulation
by IFNγ or viral infection [52,53]. In vivo treatment
with IFNγ or IL12\IL2 up-regulates both hepatocyte
and non-parenchymal cell expression of CXCL9 [7].
CXCL9 acts by binding to CXCR3. Unlike other
CXC chemokines, CXCL9, CXCL10 and CXCL11 are
not chemotactic for neutrophils, but induce chemotaxis
of activated lymphocytes [52]. These chemokines can also
inhibit the biological functions of CC chemokines by
binding to CC chemokine receptor 3 (CCR3) [54].
CXCL9 expression occurs on sinusoidal epithelial cells
in both normal and hepatitis C-infected liver tissue,
and expression is up-regulated in the latter tissue [55].
This expression of CXCL9 is associated with hepatic
infiltration by CXCR3-positive T cells, suggesting that
the interaction between CXCR3 and its ligands is important in recruiting lymphocytes to sites of inflammation
within liver tissue. Whether this particular chemokine–
# 2003 The Biochemical Society and the Medical Research Society
51
52
K. J. Simpson and others
chemokine-receptor interaction is harmful or beneficial
to the liver remains to be defined. In contrast with the
situation in hepatitis C infection, in which CXCL10
appears to be more important, CXCL9 is strongly
expressed on vascular and sinusoidal endothelium in
primary hepatic tumours, and induces the chemotaxis
of tumour-infiltrating lymphocytes [56]. CXCL10 is
not expressed on endothelium in either primary or
secondary hepatic tumours. Thus, in the case of cancer,
the augmentation of CXCL9 expression to perpetuate the
pro-inflammatory response may provide a beneficial
therapeutic option that remains to be investigated.
Expression of CXCL9 and of other CXCR3 ligands (i.e.
CXCL10 and CXCL11) is induced in rejecting hepatic
allografts [57]. This was correlated with the increased
expression of CXCR3 on circulating and hepatic
lymphocytes, suggesting that these chemokines may be
therapeutic targets for the treatment of allograft rejection.
studies have demonstrated a hepatoprotective effect
of CXCL10 [59,60]. Paracetamol poisoning induces
hepatic CXCL10 and CXCR3 expression [60]. Recombinant CXCL10 administered 10 h after paracetamol
poisoning, when liver injury is established, improves
murine survival and hepatic histology. This effect is
mediated via induction of CXCR2 expression on hepatocytes, and is limited by the immunoneutralization of
CXCR2 [60]. Others have suggested that the hepatoprotective effects of CXCL10 are mediated by the
stimulation of hepatocyte growth factor production from
hepatocytes [59]. Alternatively, human hepatic stellate
cells are important in hepatic regeneration following
acute injury, and also express CXCR3 [61]. Exposure
of these stellate cells to CXCL10 activates a number of
intracellular signalling pathways and induces their
chemotaxis, but not proliferation, providing another
potential effect of CXCL10 in the liver’s response to
injury.
CXCL10 (IP10)
CXCL11 [IFNγ-inducible T cell αchemoattractant (I-TAC)]
CXCL10 (IP10), in common with CXCL9 (MIG), is
released from cells, including hepatocytes, stimulated by
IFNγ. CXCL10 also binds to CXCR3. CXCL10 is
expressed in the liver during experimental models of
sepsis and hepatic I\R. In the latter model, pretreatment
with IFNγ to up-regulate IP10 shifts hepatic expression
from ELR-positive chemokines to non-ELR-positive
CXC chemokines, such as CXCL10 [26]. This alteration
in the chemokine balance resulted in a decrease in liver
and lung injury, but had no effect on hepatic neutrophil
influx [26]. Thus manipulation of chemokine levels may
provide important prophylactic treatment in liver surgery
that may potentially lead to I\R injury.
Hepatic CXCL10 expression is also increased in
experimental models of alcoholic liver disease. Highest
expression was reported in the animals with the greatest
degree of liver injury [44]. CXCL10, in common with
CXCL9, is expressed in liver tissue from patients
with hepatitis C infection, and relates to hepatic infiltration with CXCR3-positive T cells within the hepatic
lobules [55]. Expression of CXCL10 is more specific
for hepatic inflammation than that of CXCL9, and is
undetectable in normal liver tissue. In vitro, sinusoidal
lining endothelial cells release higher concentrations of
CXCL10 than of CXCL9. As with CXCL9, whether this
interaction aggravates or attenuates hepatic injury is not
clear. Hepatic expression of CXCL10 is also induced in a
murine model of hepatitis B infection [58]. Interestingly,
inhibition of CXCL10 reduced hepatic inflammation and
liver injury, but did not affect the anti-viral potential of
transferred virus-specific cytotoxic lymphocytes, which
is dependent on IFNγ production.
In contrast with the potential for CXCL10 to augment immune-mediated liver injury through the recruitment of CXCR3-positive lymphocytes, recent
# 2003 The Biochemical Society and the Medical Research Society
CXCL11 is a chemokine that was recently isolated from
IFNγ-stimulated human astrocytes. The release of this
chemokine can also be stimulated by IL1β in the same
cells, and in other cell types such as monocytes\
macrophages treated with pro-inflammatory cytokines,
microvascular endothelial cells, keratinocytes and dermal
fibroblasts. Murine CXCL11 has also been identified,
and is induced in macrophages by IFNγ and lipopolysaccharide in vitro and by endotoxaemia in vivo in the
lung, heart, small intestine and kidney [62]. The induction
of CXCL11 is strongly attenuated by glucocorticoids,
and in some cell types by the Th2 cytokines IL10 and\or
IL4. Interestingly, human neutrophils treated with TNFα
and IFNγ release CXCL11, suggesting that this
chemokine can link the innate and adaptive immune
responses by inducing T cell chemotaxis [63]. CXCL11
binds to CXCR3, and is of higher potency and efficacy
when compared with the biological responses induced by
CXCL9 or CXCL10 in activated T cells and cells
transfected with CXCR3. The expression of human
CXCL11 has been identified in pancreas, lung, thymus
and spleen, but little expression was identified within the
liver. CXCL11 and other CXCR3 ligands have been
implicated in heart allograft rejection [64], but the role of
this chemokine in the pathogenesis of liver disease
remains to be explored. The characteristics of the binding
of CXCL11, CXCL10 and CXCL9 to CXCR3 differ,
and so the biological effects of CXCL9 and CXCL10 in
liver disorders cannot be automatically assumed to also
occur with CXCL11.
CXCL12 [stromal-derived factor 1 (SDF1)]
CXCL12 is constitutively expressed and widely distributed in normal human and murine tissues, including the
Chemokines in the pathogenesis of liver disease
liver. Human and mouse CXCL12 are very similar,
differing by only a single amino acid. CXCL12 is a highly
effective lymphocyte (both T and B cell) chemoattractant,
but is also chemotactic for monocytes, neutrophils and
haemopoietic CD34j stem cells [65–67]. CXCL12 is
also able to inhibit entry of HIV into cells expressing
CXCR4 [68]. The specificity of the interaction between
CXCL12 and CXCR4 is illustrated by the abnormalities
found in CXCL12 or CXCR4 knockout mice [69,70].
These two types of genetically modified mice have similar
defects, which include cerebellar, vascular and cardiac
abnormalities, and defective foetal liver B cell lymphopoiesis. Studies in aborted human foetuses have demonstrated CXCL12 expression in biliary ductal plate epithelial cells, which may support B cell production in the
late stages of gestation. However, the role of CXCL12 in
the development of the biliary ductal plate is not clear, as
CXCL12 or receptor knockout animals die either in
utero or soon after birth [71]. A recent study showed that
CXCL12 expression is induced in biliary epithelium in
rejecting hepatic allografts, and this is correlated with
infiltration by CXCR4-expressing lymphocytes [57].
The role of this chemokine in the pathogenesis of other
biliary disorders remains to be defined. Although transformed hepatoma cell lines express CXCR4, the receptor
is uncoupled from downstream signalling events [72],
suggesting that the binding of CXCL12 to its receptor is
not a candidate chemokine–chemokine-receptor interaction important in determining the metastasis of hepatoma cells (unlike in breast carcinoma [73]). In addition,
immunohistochemical studies have shown reduced
CXCL12 expression in hepatocellular carcinoma compared with other chronic liver diseases, such as hepatitis
C infection [74,75].
Other CXC chemokines
CXCL4 is released from the α granules of platelets and,
like other CXC chemokines, is chemotactic for neutrophils; however, CXCL4 is also chemotactic for other cell
types, including monocytes and fibroblasts. The receptor
via which this chemokine exerts its biological effects has
yet to be characterized. Uptake and intracellular processing of CXCL4 by hepatocytes has been reported via
the endosome pathway [76]. Increased circulating
CXCL4 levels have been reported in patients with
decompensated cirrhosis, reflecting the platelet activation
associated with this disease or reduced clearance by the
damaged liver [77]. Increased circulating CXCL4 has also
been reported after liver transplantation [78]. However
the roles of CXCL4 and other CXC chemokines, such as
CXCL6 (granulocyte chemoattractant protein 2, GCP2),
CXCL7 (neutrophil-activating protein 2, NAP2),
CXCL13 (B-cell-attracting chemokine-1, BCA-1; Blymphocyte chemoattractant, BLC), CXCL14 (breast
and kidney expressed chemokine, BRAK; bolekine),
CXCL15 (Lungkine) and CXCL16 (SexCKine), in the
pathogenesis of liver diseases remain to be characterized.
As discussed above, although further studies may show
some of these chemokines to be expressed in inflammed
liver tissue, their role in the pathogenesis of liver diseases
may be more complex than the recruitment of immune
cells.
CC CHEMOKINES
To date, 28 CC chemokines have been identified and
characterized. However, for many of these chemokines,
especially the more recently characterized, their role
in the pathogenesis of liver diseases remains to be
elucidated. The following discussion focuses on those
CC chemokines for which data exist with regard to a
role in liver disorders.
CCL2 [MCP1, monocyte chemotactic and
activating factor (MCAF)]
CCL2 was first purified from lipopolysaccharide- or
phytohaemagglutinin-stimulated
peripheral
blood
mononuclear cells, a glioblastoma cell line and THP1
cells. The expression of CCL2, and its murine homologue
JE, can be induced in many cell types, including hepatocytes, Kupffer cells and stellate cells [79]. Interestingly,
transfection of a transformed hepatocyte cell line with
the hepatitis B X protein down-regulated CCL2 expression [80]. The effects of CCL2 are mediated by
binding to CCR2, which is expressed on monocytes, T
lymphocytes and basophils [79].
In a model of sepsis induced by caecal ligation and
puncture, the expression of CC chemokines, including
CCL2, is dramatically up-regulated in the liver. The
cellular source of this increased CCL2 expression is not
known. However, other studies have shown that CCL2
levels are elevated in serum and liver due to its production
from monocytes\macrophages [81,82]. When these cells
were inhibited with gadolinium chloride, there was a
significant decrease in the systemic levels of CCL2 [83].
CCL2 is also released by Kupffer cells following I\R in
response to both oxygen radicals and neutrophil elastase.
When either of these stimuli is inhibited, hepatic CCL2
concentrations decrease and less liver injury is observed.
In addition, CCL2 appears to be part of an amplification
loop within the liver, since it is able to modulate
polymorphonuclear leucocyte-dependent tissue injury
via up-regulation of endothelial intracellular adhesion
molecule-1 expression. These data implicate CCL2 in the
recruitment of inflammatory cells to the liver, by acting
at several sites in their movement from the circulation
into the tissues.
In patients with alcoholic hepatitis, circulating concentrations of CCL2 were increased, and spontaneous
# 2003 The Biochemical Society and the Medical Research Society
53
54
K. J. Simpson and others
production of CCL2 was increased in both intrahepatic
and peripheral blood mononuclear cells [84]. This increased production was correlated with high serum
transaminase levels, suggesting that CCL2 is linked with
hepatocyte death in this disease. Furthermore, CCL2
and other chemokines such as CXCL8, CCL3 and
CCL4 are all detected in the parenchyma at sites of inflammation in patients with alcoholic hepatitis. Experimental alcoholic liver disease also results in increased
CCL2 expression. Hepatitis C infection is also associated
with increased hepatic expression of CCL2; a concomitant increase in hepatic CCL2 and decrease in
CXCL10 was correlated with a better response to IFN
treatment in this disease [85].
CCL2 may also play an important role in the perpetuation of hepatic injury and fibrosis. In cirrhosis,
CCL2 expression is up-regulated in portal tracts, epithelial cells of regenerating bile ducts and active septa,
activated stellate cells and Kupffer cells [86]. Infiltration
of monocytes and macrophages into the portal tracts was
correlated with increased CCL2 expression. In response
to injury, hepatic stellate cells undergo a phenotypic
change from lipid-storing, relatively quiescent cells into
myofibroblast-like cells capable of increased matrix
synthesis, contraction and cytokine\chemokine synthesis. Early studies showed CCL2 expression and release
by activated stellate cells both in vivo and in vitro [87].
CCL2 is also chemotactic for hepatic stellate cells
and stimulates various intracellular signalling pathways,
including tyrosine kinases and phosphatidylinositol 3kinases, but these cells do not express CCR2 [88]. These
data suggest that there is another CCL2 receptor yet to be
characterized. Stimulation of intracellular signalling
pathways associated with proliferation and survival
suggest that CCL2 may perpetuate the transformed and
profibrotic myofibroblast phenotype and also recruit
more stellate cells to the site of fibrosis. Thus therapies
aimed at neutralizing this chemokine may decrease
fibrogenesis.
More recent data from an experimental model of
paracetamol poisoning have further elucidated the
immunomodulatory effects of CCL2 [89,90]. Hepatic
concentrations of CCL2 increase significantly after
paracetamol overdose in mice. However, in CCR2
knockout mice there was dramatically more liver injury
compared with wild-type mice. This increase in paracetamol hepatotoxicity was related to an increase in the
hepatic expression of the pro-inflammatory cytokines
IFNγ and TNFα, suggesting that CCL2 can downregulate pro-inflammatory cytokine expression. Similar
results have been observed in experimental sepsis.
Paracetamol poisoning induces the production of reactive
oxygen species in the liver. Free radicals can also stimulate
CCL2 production in transformed stellate cells and
Kupffer cells in vitro and in vivo in other oxidative liver
injury models, e.g. carbon tetrachloride [87]. In con# 2003 The Biochemical Society and the Medical Research Society
trast with paracetamol poisoning, antioxidant pretreatment with vitamin E dramatically reduced CCL2
concentrations following carbon tetrachloride. Thus
CCL2 appears to play a conflicting role during oxidative
injury in these two murine models, and further studies
are needed to elucidate the underlying mechanism.
CCL3 (MIP1α)
CCL3 was initially characterized as one of two MIPs
released from lipopolysaccharide-stimulated murine
macrophages [91]. After sequencing these proteins, it was
shown that they were identical with human LD78 and
other gene products. Human and murine CCL3 bind to
and activate cells via two chemokine receptors, namely
CCR1 and CCR5. In addition to its effects on monocytes, CCL3 is a chemoattractant for T cells, B cells and
eosinophils.
In experimental sepsis, the expression of CC
chemokines, including CCL3, is dramatically upregulated in the liver. Increased hepatic CCL3 expression
also occurs in chronic alcohol-fed rats, and in the
inflammatory infiltrates of the liver, on sinusoidal lining
cells and on intra-lobular bile ducts in the livers of mice
with GVHD due to cell transfer [92,93]. The CCL3
receptor CCR1 is expressed by liver-infiltrating CD8j
T lymphocytes, peaking in the first week after cell
transfer, but declining in the second week in this model.
In contrast, CCR5 expression is low during the first week
and increases dramatically during the second week after
transfer. Neutralization of CCR5 or CCL3 decreased the
infiltration of T lymphocytes into the liver and reduced
liver damage, as assessed by serum transaminases. Similarly, in mice that received cells from CCL3 knockout
mice, there was a decrease in the occurrence of GVHD. If
these data could be reproduced in humans with GVHD,
the interaction between CCL3 and CCR3 or CCR5 may
be a novel therapeutic target.
Cytomegalovirus (CMV) infection is common following hepatic transplantation, and can lead to a severe
acute intense hepatitis. Murine CMV (mCMV) infections
are characterized by increased hepatic CCL3 expression
[94]. Immunoneutralization of CCL3 during mCMV
infection markedly decreased natural killer (NK) cell
recruitment, while increasing the number of viral inclusion bodies in the liver. Similar findings were obtained
in mCMV-infected CCL3 knockout mice. Thus the
depletion of CCL3 decreased hepatic inflammation, but
increased the mCMV viral load. Further studies are
required to determine the clinical significance of these
observations.
CCL3 is also expressed at sites of inflammation during
alcoholic hepatitis, and is released spontaneously by
cultured peripheral blood mononuclear cells in this
disease [84]. Observational studies have also implicated
CCL3 (and CCL4) in the development of hepatic
allograft rejection [95]. Expression of CCL3 is up-
Chemokines in the pathogenesis of liver disease
regulated in sinusoidal endothelium, central veins and
infiltrating inflammatory cells in patients with rejection.
Endothelial cell CCL3 expression is up-regulated early
after the liver transplant operation, and CCL3 may thus
be important in the initial recruitment of T cells into the
graft, with subsequent amplification of the inflammatory
response by the expression of CCL2 by the recruited
cells. Successful treatment of allograft rejection with
pulse steroid therapy is associated with down-regulation
of endothelial CCL3 expression.
CCL4 (MIP1β)
In parallel with the identification of CCL3, CCL4 was
also found to be secreted from lipopolysaccharidestimulated murine macrophages [91]. Cloning and
sequencing of the gene for this chemokine showed that it
was identical with several other human genes variously
named ACT2, G26, HC21, H400, LAG1, AT744.1 and
AT744.2. Unlike those of CCL3, the biological effects of
CCL4 are mediated by binding to CCR5, but not to
CCR1. Hence the biological effects of CCL4 are more
restricted than those of CCL3.
Hepatic expression of CCL4 is increased in a number
of experimental and clinical liver disorders. CCL4 is upregulated in experimental sepsis, and is also expressed in
liver tissue from patients with alcoholic hepatitis, and
may play a similar role in hepatic allograft rejection as
described for CCL3 [84,95].
some, but not all, patients [101]. Lipopolysaccharide
injection also induces the expression of CCL5 in the
liver; this is reduced following Kupffer cell depletion,
suggesting that these cells are the source of CCL5 in vivo
in this model.
CCL7 (MCP3)
CCL7 was first identified from cytokine-stimulated
human oesteosarcoma cells, which can also secrete CCL2
(MCP1) and CCL8 (MCP2). Sequence analysis of the
MCP3 gene showed a high degree of identity with the
mouse MARC gene [102]. CCL7 is expressed in monocytes, pro-inflammatory-stimulated endothelial cells,
smooth muscle cells and human CD34j cells. CCL7,
like several other chemokines, binds to a number of
different receptors, namely CCR1, CCR2, CCR3 and
CCR10. Interestingly, CCL7 can bind to CCR5, but does
not induce signal transduction or down-regulate receptor
surface expression, and therefore will not inhibit HIV
infection. CCL7 acts as a chemoattractant for monocytes,
T lymphocytes, NK cells, dendritic cells, basophils and
eosinophils. A CCL7 (and CCL8)-positive monocyte
infiltration in portal tracts is a characteristic feature of
primary biliary cirrhosis [103]. However, the biological
significance of this finding with regard to the recruitment
of inflammatory cells in this condition has not been
defined.
CCL11 (eotaxin)
CCL5 (RANTES)
CCL5 was initially purified from thrombin-stimulated
human platelets. However, CCL5 can be synthesized by
many other cell types, including T cells, macrophages and
liver-derived dendritic cells. CCL5 expression is induced
in human hepatoma cells by bile acids, and may provide
a link between cholestasis and inflammation in conditions
such as primary biliary cirrhosis, sclerosing cholangitis
and bile duct obstruction [96]. Kupffer cells can also
produce CCL5, and expression is induced by ethanol
[97]. CCL5 binds to several chemokine receptors (CCR1,
CCR3 and CCR5) and therefore can interact with many
different cell types, being chemotactic for monocytes, T
cells, basophils and eosinophils.
Increased hepatic concentrations of CCL5 occur in
viral hepatitis, localize to the site of hepatic inflammatory
infiltrate and are correlated with the degree of liver
injury, as determined by serum transaminases [98].
Adenoviral hepatitis is also associated with increased
concentrations of CCL5, and increased hepatic
expression of CCL5 has been reported in experimental
alcoholic liver injury [99]. Hepatic eosinophil infiltration
is pronounced in patients with hepatic allograft rejection
or drug-induced hepatotoxicity [100]. In the latter
condition, the hepatic expression of CCL5 is increased in
CCL11 was first isolated from bronchoalveolar lavage
fluid from atopic guinea-pigs [104]. Human and
murine CCL11 were subsequently isolated and characterized. CCL11 is a specific eosinophil chemoattractant,
although it can also act on basophils through binding to
the receptor CCR3. As discussed above, CCR3 can bind
other chemokines, such as CCL7 and CCL5. CCL11 is
expressed in foetal liver and, along with stem cell factor,
is important in mast cell development [105]. Northern
blot analysis has not shown constitutive expression in
liver tissue from adult donors. However, CCL11 expression is found in the majority of patients with druginduced liver disease, a disorder that is associated with a
heavy eosinophil infiltrate [101].
CCL12 (MCP5)
CCL12 was identified from a murine genomic library
and has yet to be isolated in humans [106]. It acts as a
chemoattractant for monocytes, T lymphocytes and
eosinophils by binding to CCR2. Constitutive expression
of CCL12 was detected in lymph nodes, and its expression is markedly induced in activated macrophages.
Up-regulation of CCL12 expression was also noted
within the lungs following infection or allergen challenge.
Immunoneutralization of CCL12 reduced bronchial
# 2003 The Biochemical Society and the Medical Research Society
55
56
K. J. Simpson and others
reactivity in this model [107]. CCL12 has also been
implicated in the pathogenesis of experimental allergic
encephalomyelitis [108]. Lipopolysaccharide injection
results in increased CCL12 concentrations in murine
liver, and these increases are abrogated in Kupffer celldepleted mice, suggesting that tissue macrophages are the
source of CCL12 in vivo [109]. However, the role of
CCL12 in the pathogenesis of murine liver disorders
remains to be defined.
CCL14 [human CC chemokine-1 (HCC-1)]
CCL14 was first isolated from the haemofiltrate of
patients with chronic renal failure [110]. In common with
CXCL12 (SDF1) it is expressed constitutively in a wide
variety of normal tissues, including liver, and is found at
high concentrations in normal plasma. A murine homologue has not been identified. Unprocessed CCL14
binds to CCR1, and is able to stimulate monocyte Ca#+
flux and enzyme release, but not chemotaxis [111].
Proteolytic processing by serine proteases, such as
plasmin and urokinase plasminogen activator, cleaves
CCL14 to form a more active chemokine. This truncated
form of CCL14 binds to other chemokine receptors, such
as CCR3 and CCR5, and is chemotactic for a wide range
of cell types, including T lymphocytes and eosinophils
[112]. CCL14 is also able to stimulate the proliferation of
bone marrow stem cells. Increased constitutive
expression of this chemokine in the liver suggests that it
has a role in the normal physiological trafficking of
immune cells through the liver, but this requires
clarification.
CCL15 (HCC-2, leukotactin-1)
CCL15 (HCC-2) was identified during the sequencing of
the upstream region of the CCL14 gene [113]. In contrast
with CCL14, CCL15 is expressed only in the gut and
liver. It is similar to a number of other chemokines,
including CCL23, CCL6, CCL18 and CCL 9\10, which
contain six cysteine residues. CCL15 is chemotactic for
monocytes and eosinophils, and acts by binding to the
chemokine receptors CCR1 and CCR3. Further studies
are required to determine the role of this chemokine in
liver disorders.
CCL16 [HCC-4, liver-expressed chemokine
(LEC), LMC, NCC-4]
CCL16 is expressed in IL10-activated monocytes, but
not in resting monocytes [114]. It functions as a monocyte
chemoattractant, with no effect on neutrophils or resting
lymphocytes. CCL16 binds to CCR1, CCR2, CCR5 and
CCR8, but is a less potent agonist than other chemokines
that bind to these receptors. As might be expected from
its original name, CCL16 is constitutively expressed at
high concentrations within the liver by both hepatocytes
# 2003 The Biochemical Society and the Medical Research Society
and biliary epithelial cells [115]. Interestingly, although
CCL16 expression is inducible in other cells, treatment
of the human hepatoma cell line HepG2 with a variety of
cytokines failed to up-regulate CCL16 expression.
CCL16 may therefore play a role in the physiological
trafficking of inflammatory cells through the liver.
CCL17 [thymus- and activation-regulated
chemokine (TARC)]
CCL17 was first identified in phytohaemagglutininstimulated peripheral blood mononuclear cells. CCL17 is
constitutively expressed in the thymus and acts as a
chemoattractant by binding to CCR4 [116]. There is
some debate as to whether CCL17 can also act through
CCR8 [117]. CCL17 is a specific chemotactic factor for T
cells with a Th2 phenotype, but is also chemotactic for
macrophages, NK cells and basophils, and induces
platelet activation. CCL17 is produced by keratinocytes,
fibroblasts and lipopolysaccharide-stimulated monocytes and certain dendritic cells, and is up-regulated in
human pathological conditions associated with infiltration of T cells with a Th2 phenotype, for example
allergic respiratory conditions [118]. CCL17 also plays a
critical role in the recruitment of skin-homing memory T
cells to the sites of skin inflammation and in controlling
the inflammatory response through attracting a unique
subset of regulatory T cells [119].
Although development is normal and allergen-induced
bronchial hyper-reactivity occurs in CCR4 knockout
mice, these genetically modified mice are resistant to the
toxic effects of lipopolysaccharide injection, including
the associated liver injury [120]. Mice primed with heatkilled Propionibacterium acnes develop severe hepatocellular necrosis following lipopolysaccharide injection.
This liver injury is associated with hepatic lymphocyte
infiltration and both TNFα- and Fas\Fas ligand-induced
hepatocellular necrosis. Injection of P. acnes leads to a
granulomatous hepatitis. Preliminary data suggest that
there is up-regulation of hepatic CCL3, CXCL9 and
CXCL10, and recruitment of Th1 CD4j T cells to the
liver. In contrast, following lipopolysaccharide injection,
hepatic expression of these chemokines is reduced and
CCL17 is up-regulated in macrophage-like cells, with
recruitment of Th2-type CCR4-expressing lymphocytes
into the liver [121]. Immunoneutralization of CCL17
significantly reduced liver injury and improved survival
in this murine model. Furthermore, reduced expression
of IL4 by recruited CD4j lymphocytes suggested that
neutralization of this chemokine selectively reduced the
recruitment of T cells with a Th2 phenotype. There was
also a significant decrease in the recruitment of other
non-CCR4-expressing effector cells, such as CD8j T
cells and NKT cells, indicating that inhibition of CCL17
has immunomodulatory effects beyond the recruitment
of cells expressing CCR4.
Chemokines in the pathogenesis of liver disease
CCL20 [MIP3α, liver- and activationregulated chemokine (LARC), Exodus 1]
CCL20, as discussed above, was identified in parallel
with CCL19 [122], but had also been cloned and identified by alternative names such as liver- and activationregulated chemokine (LARC) by other groups [123].
CCL20 is expressed constitutively in many different
tissues, including liver, and therefore may be important
in the homoeostatic trafficking of dendritic cells and
lymphocytes through these tissues. The relatively high
levels of CCL20 expression in the liver may reflect the
great exposure of this organ to potentially infectious
micro-organisms, or their products, passing through the
gut.
CCL20 is chemotactic for cytokine-stimulated neutrophils, immature dendritic cells and memory\effector T
and B lymphocytes by utilizing CCR6 [124]. Expression
of CCL20 is up-regulated in certain cell types by
lipopolysaccharide and pro-inflammatory cytokines, including TNFα and IL1β. Increased tissue levels of CCL20
have been reported in several inflammatory conditions,
such as atopic dermatitis. As such, CCL20 has been
implicated as a key chemokine in the arrest of memory T
cells on dermal microvascular endothelial cells during
inflammation [125]. A recent study has shown expression
of CCL20 in macrophages and\or dendritic cells in the
livers of patients with chronic viral hepatitis, associated
with hepatic infiltration by CCR6-positive lymphocytes
[126]. In contrast with other in vitro cell model systems,
peripheral blood-derived dendritic cells released CCL20
following phagocytosis of apoptotic hepatoma cells (antiFas-treated Huh-1 cells), linking apoptosis of hepatocytes with a developing inflammatory response [126].
The increased expression of CCR6 on intrahepatic T
lymphocytes in normal liver and the high constitutive
expression of CCL20 also led these authors to speculate
that this chemokine–chemokine-receptor interaction is
important in the normal trafficking of T cells through the
liver.
CCL21 [6Ckine, secondary lymphoid
chemokine (SLC), Exodus 2, thymus-derived
chemotactic agent 4]
CCL21 was cloned from a mouse thymic cDNA library,
and is expressed in other tissues, including spleen, heart
and kidney [127]. CCL21 is chemotactic for mature
dendritic cells, naı$ ve and memory T cells, B cells and
cultured renal mesangial cells by binding to CCR7 [128].
Murine CCL21 is also able to bind to and signal through
CXCR3, in contrast with human CCL21 [129]. Physiologically, CCL21 may function in the homoeostatic
recirculation of lymphocytes in vivo. Recent data have
also implicated CCL21 in the homoeostatic proliferation
of CD4j T cells and progression toward autoimmune
disease [130]. Others have highlighted the complexity of
the chemokine system and the danger of implicating a
role for chemokines in vivo from in vitro data, using
CCL21 as an example [131].
Organ-specific transgenic expression of CCL21
is associated with various inflammatory infiltrates,
depending on the site of expression. Increased expression
of CCL21 in the pancreas was associated with lymphocyte recruitment and the development of lymphoid
node-like structures. In contrast, expression in the brain
led to the recruitment of eosinophils and neutrophils,
possibly due to the up-regulation of KC, MIP2 and
CCL11, and expression in the skin was not associated
with any inflammatory infiltration [132]. In vivo studies
have shown expression of CCL21 in the small vascular
channels associated with portal inflammatory infiltrates
in murine granulomatous hepatitis and human cholestatic
liver diseases [133,134]. In the human studies the expression of CCL21 was associated with infiltration with
CCR7-expressing lymphocytes. Interestingly, neutralization of CCL21 in the murine model, although reducing
portal tract-associated lymphoid tissue, interfered with
dendritic cell migration, limiting local and draining
lymph node immune responses. This resulted in failure
to eliminate the infective agent inducing the granulomata,
with persistence of hepatic granulomas and liver damage.
CCL22 [macrophage-derived chemokine
(MDC), stimulated T-cell chemoattractant
protein 1 (STCP-1)]
CCL22 was identified from a human monocyte-derived
macrophage cDNA library. It has very little identity with
other CC chemokines. CCL22 is chemotactic for Th2type lymphocytes, mature dendritic cells and activated
NK cells [135]. CCL22 is constitutively expressed by
dendritic cells, B lymphocytes and macrophages, and is
highly expressed in cytokine-stimulated monocytes\
macrophages and monocyte-derived dendritic cells. Tissue expression has been identified in thymus, lung and
spleen. CCL22 acts by binding to the chemokine receptor
CCR4 [136]. In keeping with a chemotactic activity for
Th2 lymphocytes, this chemokine has been implicated in
allergic disease, such as murine models of asthma. CCL22
can also inhibit the entry of HIV into cells. As noted
above, CCR4 knockout mice are more susceptible to
sepsis. CCL22 plays a central role in the systemic
response to sepsis in the murine model of caecal ligation
and puncture [137]. This model is associated with
significant liver injury. Immunoneutralization of CCL22
increased murine mortality, increased the hepatic expression of TNFα, MIP2, KC and CCL3, and increased
hepatic neutrophil infiltration and liver injury. Recombinant CCL22 had the opposite effects, suggesting that
this chemokine has an important immunoregulatory role
and may be an adjunct to therapy in sepsis.
# 2003 The Biochemical Society and the Medical Research Society
57
58
K. J. Simpson and others
CCL25 [thymus-expressed chemokine
(TECK)]
CCL25 was identified in the thymus of both mouse and
human. CCL24 is also expressed in the small intestine,
and at lower levels in the liver [138]. At a cellular level,
CCL25 is expressed in dendritic cells, but the cellular
source within the liver has not been identified. CCL25 is
chemotactic for activated macrophages, dendritic cells, T
lymphocytes and thymocytes, and inhibits myeloid
progenitor proliferation through binding to CCR9 and
CCR10 [139,140]. CCL25 may play a key role in T cell
development [141]; however, T lymphocytes develop
normally in CCR9 knockout mice. Perhaps of relevance
to hepatocyte apoptosis is the interesting observation
that Fas-mediated apoptosis of a human T cell line was
partially inhibited by CCL25 [142].
OTHER CHEMOKINES
CX3CL1 (fractalkine)
The chemokine CX3CL1 (fractalkine) has an unusual
structure [143,144]. The gene product for this chemokine
contains a transmembrane region and a mucin-like stalk
on which a chemokine domain is located. In this
chemokine domain the two N-terminal cysteine
molecules are separated by three different amino acids.
The membrane-bound form of CX3CL1 is induced in
activated primary endothelial cells and promotes strong
adhesion of T cells and monocytes [145]. Proteolytic
cleavage by TNFα-converting enzyme (ADAM17)
results in shedding of membrane-bound CX3CL1 from
the cell surface [146,147]. The receptor for CX3CL1 is
abundantly expressed in brain and lung tissue, and occurs
in other tissues, including the liver. More recent studies
have implicated CX3CL1 in the pathogenesis of brain
[148] and cardiac [149] disorders, as well as preventing
HIV infection of cells [150].
Our recent studies have implicated CX3CL1 in the
hepatic reparative response following paracetamol
poisoning because of its unique function in leucocyte
trafficking [151]. Constitutive expression of CX3CL1
mRNA was identified in Kupffer cells and hepatocytes,
especially the hepatocytes around the central veins. These
observations were further explored by studying CX3CL1
knockout and transgenic mice. At 6 h after paracetamol
injection, serum transaminases (as a circulating measure
of hepatic injury) were significantly increased in the
transgenic mice compared with wild-type controls; conversely, serum transaminases were significantly lower in
CX3CL1 knockout mice at the same time point. To
further investigate the potential for CX3CL1 to augment
hepatic injury following paracetamol poisoning via increasing neutrophil influx, hepatic myeloperoxidase was
quantified. At 6 and 24 h post-paracetamol, significantly
higher hepatic myeloperoxidase levels were found in the
# 2003 The Biochemical Society and the Medical Research Society
transgenic mice compared with the wild-type controls,
and significantly lower levels of myeloperoxidase were
detected in the liver samples from the knockout mice
compared with wild-type controls. In contrast with these
data, others have suggested that paracetamol injury may
be mediated via extensive Fas-mediated apoptosis of
hepatocytes [152]. CX3CL1 is protective against Fasmediated apoptosis in certain brain cells. However, we
have not found alterations in mortality or liver injury
following Fas injection in CX3CL1 transgenic mice.
Other preliminary data have shown up-regulation of
CX3CL1 mRNA in the murine concanavalin A hepatitis
model; inhibition of chemokine expression is associated
with reduced production of pro-inflammatory cytokines
and improved survival. Others have shown that both
CX3CL1 and its receptor are expressed in human liver
tissue following injury; furthermore, the human hepatoma cell line HepG2 expresses both CX3CL1 and its
receptor, and cells migrate when exposed to CX3CL1
[153]. These data suggest that overexpression of
CX3CL1 in the liver exacerbates liver injury associated
with paracetamol poisoning by increasing neutrophil
recruitment and oxidative injuries.
XCL1 (lymphotactin)
In contrast with other members of the chemokine
superfamily, lymphotactin has just two cysteine residues,
only one of which is located at the N-terminus; hence the
designation of this chemokine as XCL1 [also known as
lymphotactin, single C motif-1 (SCM-1) and activationinduced T-cell-derived and chemokine-related molecule
(ATAC)]. In humans there are two closely related
proteins, XCL1 and XCL2 (also called SCM-1α), which
differ by only two N-terminal amino acids and are the
products of two separate genes. The mouse has a single
gene and protein product. XCL1 is released from T cells,
NK cells, γ\δ T cells and mast cells. XCL1 mRNA was
not expressed in human liver tissue when analysed by
Northern blot [154]. XCL1 mRNA was most strongly
expressed in splenic tissue, and is induced in this organ
following murine γ herpes virus-68 infection in IFNγ
knockout mice [155]. Incidentally, this model is also
associated with reversible hepatic fibrosis and is the
subject of further study. Recently the orphan chemokine
receptor G-protein-coupled receptor 5 (GPR5) has been
identified as the receptor for both XCL proteins, and
designated XCR1. Northern blot analysis of XCR1
mRNA has identified expression in human placenta,
spleen and thymus, but not human liver.
CONCLUSION
Over the past decade, an increasing number of
chemokines have been identified and characterized. This
expansion in our knowledge of this family of cytokines
Chemokines in the pathogenesis of liver disease
has outstripped our understanding of their biological
roles. It is now clear that the functions of chemokines
include angiogenesis and angiostasis, carcinogenesis and
cell cycle control. Recent data have cautioned against the
translation of in vitro data into the in vivo or clinical
situation. Nevertheless, an understanding of the roles
that chemokines play in the pathogenesis of liver disease
lags behind that for other conditions such as respiratory
disorders or haematological conditions. Chronic liver
disease is a major worldwide health problem that is set to
become more common with increases in alcohol consumption, the incidence of obesity and the relative
frequency of viral hepatitis in most populations. With the
increasing development of chemokine or chemokine
receptor blocking agents that are effective in treating
inflammatory or fibrotic disease, the liver appears to
represent fertile ground for further study.
14
15
16
17
18
19
REFERENCES
1
2
3
4
5
6
7
8
9
10
11
12
13
Hepatitis Control Report (2001) 6, 1–3
Chief Medical Officer for England (2001) Annual
Report, HMSO, London
Proudfoot, A. E., Power, C. A. and Wells, T. N. (2000)
The strategy of blocking the chemokine system to
combat disease. Immunol. Rev. 177, 246–256
Schall, T. J. and Bacon, K. B. (1994) Chemokines,
leukocyte trafficking, and inflammation. Curr. Opin.
Immunol. 6, 865–873
Kunkel, S. L. (1999) Through the looking glass : the
diverse in vivo activities of chemokines. J. Clin. Invest.
104, 1333–1334
Zlotnik, A. and Yoshie, O. (2000) Chemokines : a new
classification system and their role in immunity.
Immunity 12, 121–127
Rowell, D. L., Eckmann, L., Dwinell, M. B., Carpenter,
S. P., Raucy, J. L., Yang, S. K. and Kagnoff, M. F. (1997)
Human hepatocytes express an array of
proinflammatory cytokines after agonist stimulation or
bacterial invasion. Am. J. Physiol. 273, G322–G332
Liang, J., Yamaguchi, Y., Matsumura, F. et al. (2000)
Calcium-channel blocker attenuates Kupffer cell
production of cytokine-induced neutrophil
chemoattractant following ischemia–reperfusion in rat
liver. Dig. Dis. Sci. 45, 201–209
Maher, J. J., Lozier, J. S. and Scott, M. K. (1998) Rat
hepatic stellate cells produce cytokine-induced
neutrophil chemoattractant in culture and in vivo. Am.
J. Physiol. 275, G847–G853
Ohkubo, K., Masumoto, T., Horiike, N. and Onji, M.
(1998) Induction of CINC (interleukin-8) production in
rat liver by non-parenchymal cells. J. Gastroenterol.
Hepatol. 13, 696–702
Mosher, B., Dean, R., Harkema, J., Remick, D., Palma,
J. and Crockett, E. (2001) Inhibition of kupffer cells
reduced CXC chemokine production and liver injury.
J. Surg. Res. 99, 201–210
Hisama, N., Yamaguchi, Y., Ishiko, T., et al. (1996)
Kupffer cell production of cytokine-induced neutrophil
chemoattractant following ischemia\reperfusion injury
in rats. Hepatology 24, 1193–1198
Mercer-Jones, M. A., Shrotri, M. S., Peyton, J. C.,
Remick, D. G. and Cheadle, W. G. (1999) Neutrophil
sequestration in liver and lung is differentially regulated
by C-X-C chemokines during experimental peritonitis.
Inflammation 23, 305–319
20
21
22
23
24
25
26
27
28
29
30
Walley, K. R., Lukacs, N. W., Standiford, T. J., Strieter,
R. M. and Kunkel, S. L. (1997) Elevated levels of
macrophage inflammatory protein 2 in severe murine
peritonitis increase neutrophil recruitment and
mortality. Infect. Immun. 65, 3847–3851
Hogaboam, C. M., Bone-Larson, C. L., Steinhauser,
M. L., et al. (1999) Novel CXCR2-dependent liver
regenerative qualities of ELR-containing CXC
chemokines. FASEB J. 13, 1565–1574
Horbach, M., Gerber, E. and Kahl, R. (1997) Influence
of acetaminophen treatment and hydrogen peroxide
treatment on the release of a CINC-related protein and
TNF-alpha from rat hepatocyte cultures. Toxicology
121, 117–126
Deutschman, C. S., Haber, B. A., Andrejko, K., et al.
(1996) Increased expression of cytokine-induced
neutrophil chemoattractant in septic rat liver. Am. J.
Physiol. 271, R593–R600
Maltby, J., Wright, S., Bird, G. and Sheron, N. (1996)
Chemokine levels in human liver homogenates :
associations between GRO alpha and histopathological
evidence of alcoholic hepatitis. Hepatology 24,
1156–1160
Giron-Gonzalez, J. A., Rodriguez-Ramos, C., Elvira, J.,
et al. (2001) Serial analysis of serum and ascitic fluid
levels of soluble adhesion molecules and chemokines in
patients with spontaneous bacterial peritonitis. Clin.
Exp. Immunol. 123, 56–61
Maher, J. J., Scott, M. K., Saito, J. M. and Burton, M. C.
(1997) Adenovirus-mediated expression of cytokineinduced neutrophil chemoattractant in rat liver induces a
neutrophilic hepatitis. Hepatology 25, 624–630
Lentsch, A. B., Yoshidome, H., Cheadle, W. G., Miller,
F. N. and Edwards, M. J. (1998) Chemokine
involvement in hepatic ischaemia\reperfusion injury in
mice : roles for macrophage inflammatory protein-2 and
KC. Hepatology 27, 1172–1177
Zhang, P., Xie, M., Zagorski, J. and Spitzer, J. A. (1995)
Attenuation of hepatic neutrophil sequestration by antiCINC antibody in endotoxic rats. Shock 4, 262–268
Bajt, M. L., Farhood, A. and Jaeschke, H. (2001) Effects
of CXC chemokines on neutrophil activation and
sequestration in hepatic vasculature. Am. J. Physiol.
Gastrointest. Liver Physiol. 281, G1188–G1195
Faouzi, S., Burckhardt, B. E., Hanson, J. C. et al. (2001)
Anti-Fas induces hepatic chemokines and promotes
inflammation by an NF-kappa B-independent, caspase3-dependent pathway. J. Biol. Chem. 276, 49077–49082
Colletti, L. M., Kunkel, S. L., Walz, A. et al. (1996) The
role of cytokine networks in the local liver injury
following hepatic ischemia\reperfusion in the rat.
Hepatology 23, 506–514
Colletti, L. M., Green, M. E., Burdick, M. D. and
Strieter, R. M. (2000) The ratio of ELRj to ELRk
CXC chemokines affects the lung and liver injury
following hepatic ischemia\reperfusion in the rat.
Hepatology 31, 435–445
Colletti, L. M., Kunkel, S. L., Walz, A. et al. (1995)
Chemokine expression during hepatic
ischemia\reperfusion-induced lung injury in the rat. The
role of epithelial neutrophil activating protein. J. Clin.
Invest. 95, 134–141
Colletti, L. M., Green, M., Burdick, M. D., Kunkel, S. L.
and Strieter, R. M. (1998) Proliferative effects of CXC
chemokines in rat hepatocytes in vitro and in vivo.
Shock 10, 248–257
Ohkubo, K., Masumoto, T., Horiike, N. and Onji, M.
(1998) Induction of CINC (interleukin-8) production in
rat liver non-parenchymal cells. J. Gastroenterol.
Hepatol. 7, 696–702
Morland, C. M., Fear, J., McNab, G., Joplin, R. and
Adams, D. H. (1997) Promotion of leukocyte
transendothelial cell migration by chemokines derived
from human biliary epithelial cells in vitro. Proc. Assoc.
Am. Physicians 109, 372–382
# 2003 The Biochemical Society and the Medical Research Society
59
60
K. J. Simpson and others
31
32
33
34
35
36
37
38
39
40
41
42
43
44
45
46
47
48
49
Schwabe, R. F., Schnabl, B., Kweon, Y. O. and Brenner,
D. A. (2001) CD40 activates NF-kappa B and c-Jun Nterminal kinase and enhances chemokine secretion on
activated human hepatic stellate cells. J. Immunol. 166,
6812–6819
Sheron, N., Bird, G., Koskinas, J. et al. (1993)
Circulating and tissue levels of the neutrophil
chemotaxin interleukin-8 are elevated in severe acute
alcoholic hepatitis, and tissue levels correlate with
neutrophil infiltration. Hepatology 18, 41–46
Hill, D. B., Marsano, L. S. and McClain, C. J. (1993)
Increased plasma interleukin-8 concentrations in
alcoholic hepatitis. Hepatology 18, 576–580
Huang, Y. S., Chan, C. Y., Wu, J. C., Pai, C. H., Chao,
Y. and Lee, S. D. (1996) Serum levels of interleukin-8 in
alcoholic liver disease : relationship with disease stage,
biochemical parameters and survival. J. Hepatol. 24,
377–384
Shimoda, K., Begum, N. A., Shibuta, K. et al. (1998)
Interleukin-8 and hIRH (SDF1-alpha\PBSF) mRNA
expression and histological activity index in patients
with chronic hepatitis C. Hepatology 28, 108–115
Tilg, H., Ceska, M., Vogel, W., Herold, M., Margreiter,
R. and Huber, C. (1992) Interleukin-8 serum
concentrations after liver transplantation.
Transplantation 53, 800–803
Simonet, W. S., Hughes, T. M., Nguyen, H. Q.,
Trebasky, L. D., Danilenko, D. M. and Medlock, E. S.
(1994) Long-term impaired neutrophil migration in mice
over-expressing human interleukin-8. J. Clin. Invest. 94,
1310–1319
DeMeo, A. N. and Anderson, B. R. (1972) Defective
chemotaxis associated with a serum inhibitor in cirrhotic
patients. N. Engl. J. Med. 286, 735–740
Maderazo, E. C., Ward, P. A. and Quintiliani, R. (1975)
Defective regulation of chemotaxis in cirrhosis. J. Lab.
Clin. Med. 85, 621–630
Mohammed, H. H., Hayes, P. C. and Simpson, K. J.
(1998) Defective CXC chemokine induced neutrophil
chemotaxis in patients with liver failure. Hepatology 28,
87
Mohammed, H. H., Jalan, R., Damink, S. O., Hayes,
P. C. and Simpson, K. J. (1999) A study of neutrophil
chemotaxis towards CXC chemokines and the effect of
simulated bleeding in patients with cirrhosis.
Hepatology 30, 282
Mohammed, H. H., Sadler, K. M., Hayes, P. C., Ross,
J. A. and Simpson, K. J. (2000) Neutrophil chemotaxis
and expression of CXCR1 and CXCR2 in patients with
chronic liver failure. Hepatology 32, 674
Afford, S. C., Fisher, N. C., Neil, D. A. et al. (1998)
Distinct patterns of chemokine expression are associated
with leukocyte recruitment in alcoholic hepatitis and
alcoholic cirrhosis. J. Pathol. 186, 82–89
Nanji, A. A., Jokelainen, K., Rahemtulla, A. et al. (1999)
Activation of nuclear factor kappa B and cytokine
imbalance in experimental alcoholic liver disease in the
rat. Hepatology 30, 934–943
Bautista, A. P. (1997) Chronic alcohol intoxication
induces hepatic injury through enhanced macrophage
inflammatory protein-2 production and intercellular
adhesion molecule-1 expression in the liver. Hepatology
25, 335–342
Hogaboam, C. M., Simpson, K. J., Chensue, S. W. et al.
(1999) Macrophage inflammatory protein-2 gene therapy
attenuates adenovirus and acetaminophen-mediated
hepatic injury. Gene Ther. 6, 573–584
Hogaboam, C. M., Bone-Larson, C. L., Steinhauser,
M. L. et al. (1999) Novel CXCR2-dependent liver
regenerative qualities of ELR-containing CXC
chemokines. FASEB J. 13, 1565–1574
Horiguchi, H., Harada, A., Oguma, E. et al. (2000)
Cadmium-induced acute hepatic injury is exacerbated in
human interleukin-8 transgenic mice. Toxicol. Appl.
Pharmacol. 163, 231–239
Yoshidome, H., Kato, A., Edwards, M. J. et al. (1999)
Activation and lung injury induced by hepatic
ischaemia-reperfusion. Am. J. Physiol. 277, L919–L923
# 2003 The Biochemical Society and the Medical Research Society
50
51
52
53
54
55
56
57
58
59
60
61
62
63
64
65
Yoshidome, H., Kato, A., Miyazaki, M., Edwards, M. J.
and Lentsch, A. B. (1999) IL-13 activates STAT 6 and
inhibits liver injury induced by ischaemia\reperfusion.
Am. J. Pathol. 155, 1059–1064
Nakamura, K., Okada, M., Yoneda, M. et al. (2001)
MIP2 induced by TNF alpha plays a pivotal role in
ConA induced liver injury. J. Hepatol. 35, 217–224
Farber, J. M. (1997) Mig and IP-10 : CXC chemokines
that target lymphocytes. J. Leukocyte Biol. 61, 246–257
Park, J. W., Gruys, M. E., McCormick, K. et al. (2001)
Primary hepatocytes from mice treated with IL-2\IL-12
produce T cell chemoattractant activity that is
dependent on monokine induced by IFN-gamma (Mig)
and chemokine responsive to gamma-2 (Crg-2).
J. Immunol. 166, 3763–3770
Loetscher, P., Pellergrino, A., Gong, J. H. et al. (2001)
The ligands of CXC chemokine receptor 3, I-TAC, Mig,
and IP10, are natural antagonists for CCR3. J. Biol.
Chem. 276, 2986–2991
Shields, P. L., Morland, C. M., Salmon, M., Qin, S.,
Hubscher, S. G. and Adams, D. H. (1999) Chemokine
and chemokine receptor interactions provide a
mechanism for selective T cell recruitment to specific
liver compartments within hepatitis C-infected liver.
J. Immunol. 163, 6236–6243
Yoong, K. F., Afford, S. C., Jones, R. et al. (1999)
Expression and function of CXC and CC chemokines in
human malignant liver tumors : a role for human
monokine induced by gamma-interferon in lymphocyte
recruitment to hepatocellular carcinoma. Hepatology 30,
100–111
Goddard, S., Williams, A., Morland, C. M. et al. (2001)
Differential expression of chemokines and chemokine
receptors shapes the inflammatory response in rejecting
human liver transplants. Transplantation 72, 1957–1967
Kakimi, K., Lane, T. E., Chisari, F. V. and Guidotti,
L. G. (2001) Inhibition of hepatitis B virus replication
by activated NK-T cells does not require inflammatory
cell recruitment to the liver. J. Immunol. 167, 6701–6705
Koniaris, L. G., Zimmers-Koniaris, T., Hsiao, E. C.,
Chavin, K., Sitzmann, J. V. and Farber, J. M. (2001)
Cytokine-responsive gene-2\IFN-inducible protein-10
expression in multiple models of liver and bile duct
injury suggests a role in tissue regeneration. J. Immunol.
167, 339–406
Bone-Larson, C. L., Hogaboam, C. M., Evanhoff, H.,
Strieter, R. M. and Kunkel, S. L. (2001) IFN-gammainducible protein-10 (CXCL 10) is hepatoprotective
during acute liver injury through the induction of
CXCR2 on hepatocytes. J. Immunol. 167, 7077–7083
Pinzani, M. and Marra, F. (2001) Cytokine receptors
and signaling in hepatic stellate cells. Semin. Liver Dis.
21, 397–416
Widney, D. P., Xia, Y. R., Lusis, A. J. and Smith, J. B.
(2000) The murine chemokine CXCL 11 (IFN-inducible
T cell alpha chemoattractant) is an IFN-gamma and
lipopolysaccharide-inducible glucocorticoid-attenuated
response gene expressed in lung and other tissues during
endotoxemia. J. Immunol. 164, 6322–6331
Gasperini, S., Marchi, M., Calzetti, F. et al. (1999) Gene
expression and production of the monokine induced by
IFN-gamma (Mig), IFN-inducible T cell alpha
chemoattractant (I-TAC), and IFN-gamma inducible
protein-10 (IP-10) chemokines by human neutrophils.
J. Immunol. 162, 4928–4937
Meyer, M., Hensbergen, P. J., van der Raaij-Helmer,
E. M. et al. (2001) Cross reactivity of three T cell
attracting murine chemokines stimulating the CXC
chemokine receptor CXCR3 and their induction in
cultured cells and during allograft rejection. Eur. J.
Immunol. 31, 2521–2527
Aiuti, A., Webb, I. J., Bleul, C., Springer, T. and
Gutierrez-Ramos, J. C. (1997) The chemokine SDF-1 is
a chemoattractant for human CD34j hematopoietic
progenitor cells and provides a new mechanism to
explain the mobilization of CD34j progenitors to
peripheral blood. J. Exp. Med. 185, 111–120
Chemokines in the pathogenesis of liver disease
66
67
68
69
70
71
72
73
74
75
76
77
78
79
80
81
82
Bleul, C. C., Fuhlbrigge, R. C., Casasnovas, J. M., Aiuti,
A. and Springer, T. A. (1996) A highly efficacious
lymphocyte chemoattractant, stromal cell derived factor
1 (SDF-1). J. Exp. Med. 184, 1101–1109
Ueda, H., Siani, M. A., Gong, W., Thompson, D. A.,
Brown, G. G. and Wang, J. M. (1997) Chemically
synthesized SDF-1 alpha analogue, N33A, is a potent
chemotactic agent for CXCR4\Fusin\LESTRexpressing human leukocytes. J. Biol. Chem. 272,
24966–24970
Bleul, C. C., Farzan, M., Choe, H., et al. (1996) The
lymphocyte chemoattractant SDF-1 is a ligand for
LESTR\fusin and blocks HIV-1 entry. Nature
(London) 382, 829–833
Zou, Y. R., Kottmann, A. H., Kuroda, M., Taniuchi, I.
and Littman, D. R. (1998) Function of the chemokine
receptor CXCR4 in haematopoiesis and in cerebellar
development. Nature (London) 393, 595–599
Ma, Q., Jones, D., Borghesani, P. R. et al. (1998)
Impaired B-lymphopoiesis, myelopoiesis, and derailed
cerebellar neuron migration in CXCR4 and SDF-1deficient mice. Proc. Natl. Acad. Sci. U.S.A. 95,
9448–9953
Coulomb-L’Hermin, A., Amara, A., Schiff, C. et al.
(1999) Stromal cell-derived factor 1 (SDF-1) and
antenatal human B cell lymphopoiesis : expression of
SDF-1 by mesothelial cells and biliary ductal plate
epithelial cells. Proc. Natl. Acad. Sci. U.S.A. 96,
8585–8590
Mitra, P., De, A., Ethier, M. F. et al. (2001) Loss of
chemokine SDF-1alpha mediated CXCR4 signalling and
receptor internalization in human hepatoma cell line
HepG2. Cell Signalling 5, 311–319
Muller, A., Homey, B., Soto, H. et al. (2001)
Involvement of chemokine receptors in breast cancer
metastasis. Nature (London) 410, 50–56
Mitra, P., Shibuta, K., Mathai, J. et al. (1999) CXCR4
mRNA expression in colon, esophageal and gastric
cancers and hepatitis C infected liver. Int. J. Oncol. 14,
917–925
Shibuta, K., Begum, N. A., Mori, M., Shimoda, K.,
Akiyoshi, T. and Barnard, G. F. (1997) Reduced
expression of the CXC chemokine hIRH\SDF-1 alpha
mRNA in hepatoma and digestive tract cancer. Int. J.
Cancer 73, 656–662
Rucinski, B., Stewart, G. J., De Feo, P. A., Boden, G.
and Niewiarowski, S. (1987) Uptake and processing of
human platelet factor 4 by hepatocytes. Proc. Soc. Exp.
Biol. Med. 186, 361–367
el-Bassiouni, N. E., el Bassiouny, A. E., Akl, M. M. and
el-Khayat, H. R. (1997) Fibronectin, platelet factor 4 and
beta-thromboglobulin in endemic hepatosplenic
schistosomiasis : relation to acute hematemesis.
Haemostasis 27, 39–48
Porte, R. J., Blauw, E., Knot, E. A. et al. (1994) Role of
the donor liver in the origin of platelet disorders and
hyperfibrinolysis in liver transplantation. J. Hepatol. 21,
592–600
Sozzani, S., Locati, M., Zhou, D. et al. (1995) Receptors,
signal transduction, and spectrum of action of monocyte
chemotactic protein-1 and related chemokines.
J. Leukocyte Biol. 57, 788–794
Han, J., Yoo, H. Y., Choi, B. H. and Rho, H. M. (2000)
Selective transcriptional regulation in the human liver
cell by hepatitis B viral X protein. Biochem. Biophys.
Res. Commun. 272, 525–530
Matsukawa, A., Hogaboam, C. M., Lukacs, N. W.,
Lincoln, P. M., Strieter, R. M. and Kunkel, S. L. (1999)
Endogenous monocyte chemoattractant protein-1
(MCP-1) protects mice in a model of acute septic
peritonitis : cross-talk between MCP-1 and leukotriene
B4. J. Immunol. 163, 6148–6154
Matsukawa, A., Hogaboam, C. M., Lukacs, N. W.,
Lincoln, P. M., Strieter, R. M. and Kunkel, S. L. (2000)
Endogenous MCP-1 influences systemic cytokine
balance in a murine model of acute septic peritonitis.
Exp. Mol. Pathol. 68, 77–84
83
84
85
86
87
88
89
90
91
92
93
94
95
96
97
98
99
Yamaguchi, Y., Matsumara, F., Liang, J. et al. (1999)
Neutrophil elastase and oxygen radicals enhance
monocyte chemoattractant protein expression after
ischaemia\reperfusion in rat liver. Transplantation 68,
1459–1468
Fisher, N. C., Neil, D. A., Williams, A. and Adams,
D. H. (1999) Serum concentrations and peripheral
secretion of the beta chemokines monocyte
chemoattractant protein 1 and macrophage
inflammatory protein 1 alpha in alcoholic liver disease.
Gut 45, 416–420
Narumi, S., Tominaga, Y., Tamaru, M. et al. (1997)
Expression of IP10 in chronic hepatitis. J. Immunol. 158,
5536–5544
Marra, F., DeFranco, R., Grappone, C. et al. (1998)
Increased expression of monocyte chemotactic protein-1
during active hepatic fibrogenesis : correlation with
monocyte infiltration. Am. J. Pathol. 152, 423–430
Marra, F., DeFranco, R., Grappone, C. et al. (1999)
Expression of monocyte chemotactic protein-1 precedes
monocyte recruitment in a rat model of acute liver
injury, and is modulated by vitamin E. J. Invest. Med.
47, 66–75
Marra, F., Romanelli, R. G., Giannini, C. et al. (1999)
Monocyte chemotactic protein-1 as a chemoattractant
for human hepatic stellate cells. Hepatology 29, 140–148
Hogaboam, C. M., Bone-Larson, C. L., Steinhauser,
M. L., et al. (2000) Exaggerated hepatic injury due to
acetaminophen challenge in mice lacking C-C
chemokine receptor. Am. J. Pathol. 156, 1245–1252
Dambach, D. M., Watson, L. M., Gray, K. R., Durham,
S. K. and Laskin, D. L. (2002) Role of CCR2 in
macrophage migration into the liver during
acetaminophen induced hepatotoxicity in the mouse.
Hepatology 35, 1093–1103
Wolpe, S. D. and Cerami, A. (1989) Macrophage
inflammatory proteins 1 and 2 : members of a novel
superfamily of cytokines. FASEB J. 14, 2565–2573
Murai, M., Yoneyama, H., Harada, A. et al. (1999)
Active participation of CCR5j, CD8j T lymphocytes
in the pathogenesis of liver injury in graft-versus-host
disease. J. Clin. Invest. 104, 49–57
Serody, J. S., Cook, D. N., Kirby, S. L., Reap, E., Shea,
T. C. and Frelinger, J. A. (1999) Murine T lymphocytes
incapable of producing macrophage inhibitory protein-1
are impaired in causing graft-versus-host disease across a
class I but not class II major histocompatibility complex
barrier. Blood 93, 43–50
Salazar-Mather, T. P., Orange, J. S. and Biron, C. A.
(1998) Early murine cytomegalovirus (mCMV) infection
induces liver natural killer (NK) cell inflammation and
protection through macrophage inflammatory protein 1
alpha (MIP-1alpha) dependent pathways. J. Exp. Med.
187, 1–14
Adams, D. H., Hubscher, S., Fear, J., Johnston, J., Shaw,
S. and Afford, S. (1996) Hepatic expression of macrophage inflammatory protein-1 alpha and macrophage
inflammatory protein-1 beta after liver transplantation.
Transplantation 61, 817–825
Hirano, F., Kobayashi, A., Hirano, Y., Nomura, Y.,
Fukawa, E. and Makino, I. (2001) Bile acids regulate
RANTES gene expression through its cognate NFkappaB binding sites. Biochem. Biophys. Res. Commun.
288, 1095–1101
Bukara, M. and Bautista, A. P. (2000) Acute alcohol
intoxication and gadolinium chloride attenuate
endotoxin-induced release of CC chemokines in the rat.
Alcohol 20, 193–203
Kusano, F., Tanaka, Y., Marumo, F. and Sato, C. (2000)
Expression of C-C chemokines is associated with portal
and periportal inflammation in the liver of patients with
chronic hepatitis C. Lab. Invest. 80, 415–422
Muruve, D. A., Barnes, M. J., Stillman, I. E. and
Libermann, T. A. (1999) Adenoviral gene therapy leads
to rapid induction of multiple chemokines and acute
neutrophil-dependent hepatic injury in vivo. Hum.
Gene Ther. 10, 965–976
# 2003 The Biochemical Society and the Medical Research Society
61
62
K. J. Simpson and others
100
101
102
103
104
105
106
107
108
109
110
111
112
113
114
115
116
Nagral, A., Ben-Ari, Z., Dhillon, A. P. and Burroughs,
A. K. (1998) Eosinophils in acute cellular rejection in
liver allografts. Liver Transplant. Surg. 4, 355–362
Pham, B. N., Bemuau, J., Durand, F. et al. (2001)
Eotaxin expression and eosinophil infiltrate in the liver
of patients with drug-induced liver disease. J. Hepatol.
34, 537–547
Proost, P., Wuyts, A. and van Damme, J. (1996) Human
monocyte chemotactic proteins-2 and -3 : structural and
functional comparison with MCP-1. J. Leukocyte Biol.
59, 67–74
Tsuneyama, K., Harada, K., Yasoshima, M. et al. (2001)
Monocyte chemotactic protein-1, -2, and -3 are
distinctively expressed in portal tracts and granulomata
in primary biliary cirrhosis : implications for
pathogenesis. J. Pathol. 193, 102–109
Griffiths-Johnson, D. A., Collins, P. D., Rossi, A. G.,
Jose, P. J. and Williams, T. J. (1993) The chemokine,
eotoxin, activates guinea-pig eosinophils in vitro and
causes their accumulation into the lung in vivo.
Biochem. Biophys. Res. Commun. 197, 1167–1172
Quackenbush, E. J., Aguirre, V., Wershil, B. K. and
Gutierrez-Ramos, J. C. (1997) Eotoxin influences the
development of embroyonic hematopoietic progenitors
in the mouse. J. Leukocyte Biol. 5, 661–666
Sarafi, M. N., Garcia-Zepeda, E. A., MacLean, J. A.,
Charo, I. F. and Luster, A. D. (1997) Murine monocyte
chemoattractant protein (MCP-5), a novel CC chemokine that is a structural and functional homologue
of human MCP-1. J. Exp. Med. 185, 99–109
Blease, K., Mehrad, B., Lukacs, N. W., Kunkel, S. L.,
Standiford, T. J. and Hogaboam, C. M. (2001)
Antifungal and airway remodeling roles for murine
monocyte chemoattractant protein-1\CCL2 during
pulmonary exposure to Asperigillus fumigatus conidia.
J. Immunol. 166, 1832–1842
Sun, D., Tani, M., Newman, T. A. et al. (2000) Role of
chemokines, neuronal projections, and the blood-brain
barrier in the enhancement of cerebral EAE following
focal brain damage. J. Neuropathol. Exp. Neurol. 12,
1031–1043
Kopydlowski, K. M., Salkowski, C. A., Cody, M. J. et
al. (1999) Regulation of macrophage chemokine
expression by lipopolysaccharide in vitro and in vivo.
J. Immunol. 163, 1537–1544
Schulz-Knappe, P., Magert, H. J., Dewald, B. et al.
(1996) HCC-1, a novel chemokine from human plasma.
J. Exp. Med. 183, 295–299
Tsou, C. L., Gladue, R. P., Carroll, L. A. et al. (1998)
Identification of C-C chemokine receptor 1 (CCR1) as
the monocyte hemofiltrate C-C chemokine (HCC)-1
receptor. J. Exp. Med. 188, 603–608
Detheux, M., Standker, L., Vakili, J. et al. (2000)
Natural proteolytic processing of hemofiltrate CC
chemokine 1 generates a potent CC chemokine receptor
(CCR) 1 and CCR5 agonist with anti-HIV properties.
J. Exp. Med. 192, 1501–1508
Pardigol, A., Forssmann, U., Zucht, H. D. et al. (1998)
HCC-2, a human chemokine : gene structure, expression
pattern, and biological activity. Proc. Natl. Acad. Sci.
U.S.A. 95, 6308–6313
Hedrick, J. A., Helms, A., Vicari, A. and Zlotnik, A.
(1998) Characterisation of a novel CC chemokine,
HCC-4, whose expression is increased by interleukin
10. Blood 91, 4242–4247
Nomiyama, H., Heishima, K., Nakayama, T. et al.
(2001) Human CC chemokine liver-expressed
chemokine\CCL16 is a functional ligand for CCR1,
CCR2 and CCR5, and constitutively expressed by
hepatocytes. Int. Immunol. 8, 1021–1029
Imai, T., Baba, M., Nishimura, M., Kakizaki, M., Takagi,
S. and Yoshie, O. (1997) The T cell-directed CC
chemokine TARC is a highly specific biological ligand
for CC chemokine receptor 4. J. Biol. Chem. 272,
15036–15042
# 2003 The Biochemical Society and the Medical Research Society
117
118
119
120
121
122
123
124
125
126
127
128
129
130
131
132
133
Bernardini, G., Hedrick, J., Sozzani, S. et al. (1998)
Identification of the CC chemokines TARC and
macrophage inflammatory protein-1 beta as novel
functional ligands for the CCR8 receptor. Eur. J.
Immunol. 28, 582–588
Sekiya, T., Miyamasu, M., Imanishi, M. et al. (2000)
Inducible expression of a Th2 type CC chemokine
thymus and activation regulated chemokine by human
bronchial epithelial cells. J. Immunol. 165, 2205–2213
Campbell, J. J., Haraldsen, G., Pan, J. et al. (1999) The
chemokine receptor CCR4 in vascular recognition by
cutaneous but not intestinal memory T cells. Nature
(London) 400, 776–780
Chvatchko, Y., Hoogewerf, A. J., Meyer, A. et al.
(2000) A key role for CC chemokine receptor 4 in
lipopolysaccharide induced endotoxic shock. J. Exp.
Med. 191, 1755–1764
Yoneyama, H., Harada, A., Imai, T. et al. (1998) Pivotal
role of TARC, a CC chemokine, in bacteria induced
fulminant hepatic failure in mice. J. Clin. Invest. 102,
1933–1941
Yoshida, R., Imai, T., Hieshima, K. et al. (1997)
Molecular cloning of a novel human CC chemokine
EBII-ligand chemokine that is a specific functional
ligand for EBII, CCR7. J. Biol. Chem. 272, 13803–13809
Kellermann, S. A., Hudak, S., Oldham, E. R., Liu, Y. J.
and McEvoy, L. M. (1999) The CC chemokine receptor7 ligands, 6Ckine and macrophage inflammatory
protein-3 beta are potent chemoattractants for in vitro
and in vivo derived dendritic cells. J. Immunol. 162,
3859–3864
Robertson, M. J., Williams, B. T., Christopherson, II, K.,
Brahmi, Z. and Hromas, R. (2000) Regulation of human
natural killer cell migration and proliferation by the
exodus subfamily of CC chemokines. Cell. Immunol.
199, 8–14
Robbiani, D. F., Finch, R. A., Jager, D., Muller, W. A.,
Sartorelli, A. C. and Randolph, G. J. (2000) The
leukotriene C4 transporter MRP1 regulates CCL19
(MIP-3 beta, ELC) dependent mobilization of dendritic
cells to lymph nodes. Cell 103, 757–768
Shimizu, Y., Murata, H., Kashii, Y. et al. (2001) CCR6
and its ligand MIP3 alpha might be involved in the
amplification of local necroinflammatory response in the
liver. Hepatology 34, 311–319
Yoshie, O., Imai, T. and Nomiyama, H. (1997) Novel
lymphocyte specific CC chemokines and their receptors.
J. Leukocyte Biol. 62, 634–644
Yoshida, R., Nagira, M., Kitaura, M., Imagawa, N.,
Imai, T. and Yoshie, O. (1998) Secondary lymphoid
tissue chemokine is a functional ligand for the CC
chemokine receptor CCR7. J. Biol. Chem. 273,
7118–7122
Soto, H., Wang, W., Strieter, R. M. et al. (1998) The CC
chemokine 6Ckine binds the CXC chemokine receptor
CXCR3. Proc. Natl. Acad. Sci. U.S.A. 95, 8205–8210
Ploix, C., Lo, D. and Carson, M. J. (2001) A ligand for
chemokine receptor CCR7 can influence the
homeostatic proliferation of CD4 T cells and
progression of autoimmunity. J. Immunol. 167,
6724–6730
Chen, S. C., Leach, M. W., Chen, Y. et al. (2002)
Central nervous system inflammation and neurological
disease in transgenic mice expressing the CC chemokine
CCL21 in oligodendrocytes. J. Immunol. 168,
1009–1017
Chen, S. C., Vassileva, G., Kinsley, D. et al. (2002)
Ectopic expression of the murine chemokines CCL21a
and CCL21b induces the formation of lymph node like
structures in pancreas, but not skin, of transgenic mice.
J. Immunol. 168, 1001–1008
Yoneyama, H., Matsuno, K., Zhang, Y. et al. (2001)
Regulation by chemokines of circulating dendritic cell
precursors and the formation of portal tract associated
lymphoid tissue in granulomatous liver disease. J. Exp.
Med. 193, 35–49
Chemokines in the pathogenesis of liver disease
134
135
136
137
138
139
140
141
142
143
Grant, A. J., Goddard, S., Ahmed-Choudhury, J. et al.
(2002) Hepatic expression of SLC (CCL21) promotes
the development of portal associated lymphoid tissue in
chronic inflammatory liver disease. Am. J. Pathol. 160,
1445–1455
Godiska, R., Chantry, D., Raport, C. J. et al. (1997)
Human macrophage derived chemokine (MDC), a novel
chemoattractant for monocytes, monocyte derived
dendritic cells, and natural killer cells. J. Exp. Med. 185,
1595–1604
Imai, T., Chantry, D., Raport, C. J. et al. (1998)
Macrophage derived chemokine is a functional ligand for
the CC chemokine receptor 4. J. Biol. Chem. 273,
1764–1768
Matsukawa, A., Kaplan, M. H., Hogaboam, C. M.,
Lukacs, N. W. and Kunkel, S. L. (2001) Pivotal role of
signal transducer and activator of transcription (Stat) 4
and Stat 6 in the innate immune response during sepsis.
J. Exp. Med. 193, 679–688
Vicari, A. P., Figueroa, D. J., Hedrick, J. A. et al. (1997)
TECK : a novel CC chemokine specifically expressed by
thymic dendritic cells and potentially involved in T cell
development. Immunity 7, 291–301
Youn, B. S., Kim, C. H., Smith, F. O. and Broxmeyer,
H. E. (1999) TECK, an efficacious chemoattractant for
human thymocytes, uses GPR-9-6\CCR9 as a specific
receptor. Blood 94, 2533–2536
Zabel, B. A., Agace, W. W., Campbell, J. J. et al. (1999)
Human G protein coupled receptor GPR-9-6\CC
chemokine receptor 9 is selectively expressed on
intestinal homing T lymphocytes, mucosal lymphocytes,
and thymocytes and is required for thymus expressed
chemokine mediated chemotaxis. J. Exp. Med. 190,
1241–1256
Vicari, A. P., Figueroa, D. J., Hedrick, J. A. et al. (1997)
TECK : a novel CC chemokine specifically expressed by
thymic dendritic cells and potentially involved in T cell
development. Immunity 7, 291–301
Youn, B. S., Kim, Y. J., Mantel, C., Yu, K. Y. and
Broxmeyer, H. E. (2001) Blocking of c-FLIP(L)independent cycloheximide induced apoptosis or Fas
mediated apoptosis by the CC chemokine receptor
9\TECK interaction. Blood 98, 925–933
Pan, Y., Lloyd, C., Zhou, H. et al. (1997) Neurotactin, a
membrane-anchored chemokine upregulated in brain
inflammation. Nature (London) 387, 611–617
144
145
146
147
148
149
150
151
152
153
154
155
Bazan, J. F., Bacon, K. B., Hardiman, G. et al. (1997) A
new class of membrane-bound chemokine with a CX3C
motif. Nature (London) 385, 640–644
Fong, A. M., Robinson, L. A., Steeber, D. A. et al.
(1998) Fractalkine and CX3CR1 mediate a novel
mechanism of leukocyte capture, firm adhesion, and
activation under physiologic flow. J. Exp. Med. 188,
1413–1419
Tsou, C. L., Haskell, C. A. and Charo, I. F. (2001)
Tumor necrosis factor-alpha-converting enzyme
mediates the inducible cleavage of fractalkine. J. Biol.
Chem. 276, 44622–44626
Garton, K. J., Gough, P. J., Blobel, C. P. et al. (2001)
Tumor necrosis factor-alpha-converting enzyme
(ADAM17) mediates the cleavage and shedding of
fractalkine (CX3CL1). J. Biol. Chem. 276, 37993–38001
Harrison, J. K., Jiang, Y., Chen, S. et al. (1998) Role for
neuronally derived fractalkine in mediating interactions
between neurons and CX3CR1 expressing microglia.
Proc. Natl. Acad. Sci. U.S.A. 95, 10896–10901
Moatti, D., Faure, S., Fumeron, F. et al. (2001)
Polymorphism in the fractalkine receptor CX3CR1 as a
genetic risk factor for coronary artery disease. Blood 97,
1925–1928
Combadiere, C., Salzwedel, K., Smith, E. D., Tiffany,
H. L., Berger, E. A. and Murphy, P. M. (1998)
Identification of CX3CR1. A chemotactic receptor for
the human CX3C chemokine fractalkine and a fusion
co-receptor for HIV. J. Biol. Chem. 273, 23799–23804
Bone-Larson, C. L., Simpson, K. J., Colletti, L. M., et al.
(2000) The role of chemokines in the immunopathology
of the liver. Immunol. Rev. 177, 8–20
Zhang, H., Cook, J., Nickel, J. et al. (2000) Reduction
of liver Fas expression by an antisense oligonucleotide
protects mice from fulminant hepatitis. Nat. Biotechnol.
18, 862–867
Efsen, E., Grappone, C., Raffaella, M. S. et al. (2002)
Up-regulated expression of fractalkine and its receptor
CX3CR1 during liver injury in humans. J. Hepatol. 37,
39–47
Kennedy, J., Kelner, G. S., Kleyensteuber, S. et al.
(1995) Molecular cloning and functional characterization
of human lymphotactin. J. Immunol. 155, 203–209
Ebrahimi, B., Dutia, B. M., Brownstein, D. G. and Nash,
A. A. (2001) Murine gammaherpesvirus-68 infection
causes multi-organ fibrosis and alters leukocyte
trafficking in interferon-gamma receptor knockout mice.
Am. J. Pathol. 158, 2117–2125
# 2003 The Biochemical Society and the Medical Research Society
63