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Views & Reviews
Differential mechanisms of action of
interferon-␤ and glatiramer acetate in MS
V. Wee Yong, PhD
Abstract—Interferon-␤ and glatiramer acetate (GA) are the two main groups of drugs used in the treatment of MS.
Notably, while both ultimately decrease CNS inflammation, they do so by very different mechanisms. Interferon-␤ has
potent activity at the blood-brain barrier and impairs the trafficking of inflammatory cells into the CNS. In contrast, GA
has negligible effect at the blood-brain barrier, allowing GA-specific T helper 2 lymphocytes to enter the CNS to decrease
inflammation through bystander suppression. Other differences are also emphasized. The presence of GA-reactive lymphocytes within the CNS parenchyma may have the additional benefit of conferring neuroprotection through protective
autoimmunity.
NEUROLOGY 2002;59:●●●–●●●
The introduction of interferon-␤ (Betaseron, Avonex,
and Rebif) and glatiramer acetate (GA; Copaxone)
into MS therapeutics has altered the natural course
of the disease. The annualized relapse rate of drugtreated patients is lower compared to placebo controls, and more treated patients remain relapse free for
several years relative to untreated cohorts. What is
still unclear is how interferon-␤ and GA achieve their
therapeutic benefit in MS. This review discusses the
possible mechanisms by which interferon-␤ and GA
may work in MS and emphasizes their different modes
of activity. All three interferon-␤ preparations are used
interchangeably here, given that the evidence does not
suggest their activity to be different if utilized at similar concentrations, at least in vitro.
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Mechanisms of action of drugs in the periphery.
Antigen presentation and cytokines. A key concept in
immunology required to discuss this section is the phenomenon of antigen presentation. Here, a foreign molecule is first engulfed by an antigen presenting cell
(APC), which is usually a dendritic cell, macrophage, or
B cell. Part of that antigen is then displayed on the
surface of the APC within the groove of a major histocompatibility complex (MHC) molecule. The antigenMHC complex is recognized by a specific T-cell receptor
(TCR) of a responding T cell. Costimulatory molecules
are also required to provide optimal activation, including CD40 interacting with CD40L on APC, and B7
with CD28 on T cell. If the costimulatory molecules are
not engaged, the responding T cell may undergo functional inactivation (anergy) or apoptosis. Upon antigen
presentation, the T cell then undergoes clonal expansion and differentiation into effector cells. A subtype of
T cells with the CD4 molecule on its surface differentiates into two subsets: T helper 1 (Th1), and T helper 2
(Th2) cells (figure 1). The Th1 and Th2 effector arms
have important functions, including promoting cellmediated immunity (Th1) and humoral immunity
(Th2). Th1 cells produce Th1 cytokines that include
interleukin (IL)-2, IL-12, interferon-␥, and tumor necrosis factor (TNF)-␣; in general, these tend to be
proinflammatory. Th2 cells produce Th2 cytokines such
as IL-4, IL-5, and IL-10, which tend to be antiinflammatory (regulatory); indeed, Th2 cytokines can
inhibit the production of cytokines by Th1 cells or macrophages. In MS, there appears to be an elevation of
Th1 cytokines, and a diminution of Th2 cytokines, preceding and during relapse.1,2 Finally, a current concept
of MS pathogenesis is that myelin-reactive CD4⫹ Th1
cells are activated and these then traffic into the CNS
to produce disease.1-4 Thus, some of the aims of therapy
would be to decrease the generation/activation of autoreactive Th1 cells through antigen presentation, and to
produce “immune deviation” away from a Th1 milieu
toward a Th2 environment (see figure 1).
GA and interferon-␤ both affect antigen presentation and cytokine levels but by different
means. GA and interferon-␤ both affect antigen
presentation and the cytokine milieu, but they do so
by different mechanisms (figure 2). GA has high affinity for the MHC groove and is thought to bind to,
and to be displayed, as an antigen within this
From the Departments of Oncology and Clinical Neurosciences, University of Calgary, Alberta, Canada.
V.W.Y. has received honoraria from Teva Neurosciences, Berlex Laboratories and Serono, and was supported by research grants from Teva Neurosciences
and Berlex Laboratories.
Received January 15, 2002. Accepted in final form April 13, 2002.
Address correspondence and reprint requests to V. Wee Yong, PhD, Professor, Departments of Oncology and Clinical Neurosciences, 3330 Hospital Drive,
Calgary, Alberta T2N 4N1, Canada; e-mail: [email protected]
Copyright © 2002 by AAN Enterprises, Inc.
<ARTICLE DOCTOPICⴝⴖViews &amp; Reviewsⴖ DOCSUBJⴝⴖ&NA;ⴖ DATEⴝⴖSeptember (2 of 2) 2002ⴖ VIDⴝⴖ59ⴖ ISSⴝⴖ6ⴖ PPFⴝⴖ●●●ⴖ PPLⴝⴖ●●●ⴖ>
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Figure 1. Naïve CD4 helper T cells differentiate into T helper 1 (Th1) and T
helper 2 (Th2) cells. Th1 cells are proinflammatory, whereas Th2 cells are antiinflammatory or regulatory. Evidence
suggests a preponderance of Th1 cytokines in MS relapse, and elevated Th2
cytokines during remission. Thus, rational therapies include strategies to decrease the generation of autoreactive
Th1 cells, or immune deviation in favor
of a Th2 environment.
groove.5 Alternatively, GA is engulfed by APC and
fragments are then presented. Either way, the presentation of GA leads to the generation of GAspecific T cells. Through mechanisms that are still
unclear, the GA-specific T cells are predominantly
Th2 biased, as has been amply demonstrated in animal studies and in leukocytes derived from individuals with MS treated with GA.5,6 That the generation
of GA-specific Th2 cells is important is indicated by
the finding that the injection of these cells into mice
prevented experimental autoimmune encephalitis
(EAE) when animals were subsequently immunized
with spinal cord homogenates.7 EAE is an inflammatory disease in animals that bears several histologic
features of MS.
Interferon-␤ also affects antigen presentation, but
by decreasing the expression of molecules that are
necessary for this process (see figure 2). Thus,
interferon-␤ is particularly effective in preventing
the interferon-␥-induced upregulation of MHC II on
APC.1 Interferon-␤ also downregulates the expression of co-stimulatory molecules, and impacts on
other aspects of antigen presentation. As an antiproliferative agent, interferon-␤ inhibits the expansion
of T cell clones. Recently, interferon-␤ (and GA) was
shown to decrease the production by dendritic cells
of IL-12, which is required for differentiation along
the Th1 route.8 Finally, interferon-␤ inhibits the expression of FLIP, the anti-apoptotic protein, leading
to an increased incidence of death of T cells.9 Overall,
when the frequency of myelin basic protein (MBP)
reactive T cells was analyzed in MS, this was found
to be reduced following treatment with interferon-␤
compared to pretreatment levels.10 In contrast, GAreactive T cells may have a survival advantage.11
Does interferon-␤ cause a Th2 shift as is the case
for GA? The literature has been extremely confusing.
Several studies have reported the elevation of the
Figure 2. Contrasting the mechanisms of glatiramer acetate (GA) and interferon-␤ on antigen presentation. In panel A, the high
affinity of GA for the major histocompatibility complex groove or the uptake of GA by an antigen presenting cell (APC) leads to the
presentation of GA as an antigen and the generation of GA-specific cells that are T helper 2 biased. In the case of interferon-␤, which
acts on its receptor on T cells and APC, this decreases the expression of molecules needed for antigen presentation. Together with a
further activity of interferon-␤ on T cell expansion and survival, this leads to the decreased generation of antigen-specific T cells. In
both panels, x refers to an antigen that sits on the MHC groove.
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Th2 cytokine, IL-10, in the mononuclear cell fraction,
and serum and CSF of patients with MS treated
with interferon-␤,12,13 but this has not been confirmed in other studies.14 Furthermore, while the
Th1 cytokines, interferon-␥, IL-12 and TNF␣ were
decreased by interferon-␤ in a majority of studies,1
no difference, or even an increase,15,16 were noted by
others. In other studies, the number of circulating T
cells that express either Th1 or Th2 cytokines was
reduced following interferon-␤ therapy, indicating a
more general suppression of both subsets.17 Differences in experimental conditions, patient sampling,
and duration of treatment may have affected the
outcome of results. Overall, however, the majority of
studies do indicate a suppression of the generation of
autoreactive CD4⫹ Th1 cells and decrease of Th1
cytokines following interferon-␤ treatment, but a
clear deviation away from a Th1 milieu to a Th2
environment has been difficult to demonstrate.
In summary, both GA and interferon-␤ alter antigen presentation and the cytokine milieu but by different mechanisms (see figure 2). GA leads to the
formation of GA-specific Th2 cells with immunoregulatory properties, whereas interferon-␤ inhibits several aspects of antigen presentation that leads to the
generation and expansion of autoreactive T cells.
The net result of both treatments in the periphery is
the decrease of a proinflammatory milieu.
Other mechanisms in the periphery. Although
the above discussions have focused on the CD4 subset of T cells, the CD8 suppressor/cytotoxic T cells
may also be altered. Particularly, GA therapy upregulates the CD8 responses and restore these to
levels observed in healthy individuals;18 a subset of
CD8 T cells is thought to have regulatory roles in MS
and EAE.
Finally, since CD4⫹ Th2 cells activate B cells to
produce immunoglobulins (see figure 1), it is reasonable to address whether the latter is elevated in patients with MS on GA therapy. Indeed, in a study of
130 patients on GA treatment, all developed GAspecific antibodies that peaked at 3 months after
initiation of treatment. The role, if any, of these antibodies in mediating the beneficial actions of GA is
unclear; however, these antibodies did not appear to
negate clinical activity.19 A large literature exists on
the generation of antibodies to interferon-␤, and the
field remains divided as to the significance of these
antibodies.
Mechanisms of action of drugs at the bloodbrain barrier. Trafficking of inflammatory cells
into the CNS. The migration of activated T cells
into the CNS is critical to initiating and sustaining
the pathology of MS.3 In correspondence, areas of
CNS demyelination or axonal loss contain high numbers of various inflammatory cell types.20 Thus, it is
logical to address whether interferon-␤ and GA impact
on the influx of inflammatory cells into the CNS.
For T cells to infiltrate into the CNS, a number of
events are necessary. First, adhesion molecules on T
cells interact with their counter receptors on endothelial cells. These ligand pairs include the integrins
very late activation antigen-4 (VLA-4) and leukocyte
function antigen (LFA-1) on T cells, and vascular cell
adhesion molecule-1 (VCAM-1) and intercellular cell
adhesion molecule-1 (ICAM-1) on endothelial cells.
In general, these molecules are upregulated in MS.
Second, there is the expression of chemokines, which
provide a directional gradient for leukocytes to enter
the CNS, and also increase the affinity of integrins
(e.g., VLA-4) for their counterligands on endothelial
cells. Specific chemokines (e.g., IP10, MIG, and
RANTES) are present in MS lesions, and their corresponding receptors are upregulated on circulating T
cells.21,22
Once past the endothelial barrier, the leukocyte
encounters a barrier of extracellular matrix (ECM)
proteins present within the basement membrane.
Transit across the ECM barrier into the CNS parenchyma appears to require the coordinate action of
proteolytic enzymes including the matrix metalloproteinases (MMP).23
Interferon-␤ inhibits the trafficking of T cells but
GA does not. Interferon-␤ has profound activities
on several components of the process required for the
migration of inflammatory cells into the CNS. At the
level of adhesion molecules, interferon-␤ decreases
their expression. Many cell-anchored adhesion molecules are processed into a soluble form, which then
interacts with receptors on T cells, preventing the
latter from interacting with endothelial cells. The
conversion of cell-associated VCAM-1 into soluble
VCAM-1 is facilitated by interferon-␤.24 Coordinately, these mechanisms decrease the ability of T
cells to adhere on the endothelium.
At the level of chemokine and chemokine receptor
expression, interferon-␤ treatment decreases the expression of several chemokines and the CCR5 receptor,25,26 although this was not confirmed.17 These
actions should decrease the chemokine gradient that
facilitates the entry of cells into the CNS.
With respect to MMP, the production of MMP-9 by
activated T cells is decreased by interferon-␤, and
this corresponded with a decrease in the capacity of
T cells to transmigrate across a matrix barrier.27,28
Interferon-␤ treatment of patients with MS results
in the decrease of the serum content of MMP-929 and
of the number of mononuclear cells that express various MMP members.30 More recently, mononuclear
cells from patients with MS on interferon-␤ treatment
for 12 months were found to have reduced MMP-7 and
MMP-9 transcript levels; moreover, this occurred only
in patients with relapsing remitting but not secondary
progressive MS.31 The sum of the above activities of
interferon-␤ is the reduction in the number of inflammatory cells that infiltrate into the CNS (figure 3).
This is borne out in EAE where interferon-␤ treatment
decreases the number of infiltrates in afflicted
animals.32
In contrast to interferon-␤, GA does not appear to
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NEUROLOGY 59
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Figure 3. Contrasting the effects of
interferon-␤ and GA at the blood-brain
barrier and within the CNS.
Interferon-␤ decreases the production of
matrix metalloproteinases by T cells and
also affects the adhesion of T cells onto
the endothelium. These reduce the influx
of T cells into the CNS and lead to a
rapid resolution of Gd-enhancing MRI
activity. In contrast, GA-specific T
helper 2 cells traffic into the CNS to
produce bystander suppression and possible neuroprotection. The lack of action
of GA in excluding T cell infiltration
does not produce a rapid decrease of
Gd-enhancing MRI activity. Rather, due
to actions within the CNS, a delayed
reduction of MRI activity results.
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affect the transmigration of leukocytes into the CNS
(see figure 3). Thus, GA treatment does not alter the
expression of adhesion molecules on cultured endothelial cells33 and does not affect MMP production by
leukocytes (Giuliani and Yong, manuscript in preparation). High concentrations of GA applied to glioma
cells in vitro block the cytokine-induced production
of the chemokine RANTES,34 but the importance of
this to lymphocytes is unclear. In correspondence
with the lack of activity of GA on molecules that
affect transmigration, Th2 polarized GA-reactive
cells traffic readily into the CNS of EAE-afflicted
animals.35
Does the differential activity of interferon-␤ and GA
at the blood-brain barrier account for the observed clinical differences in MRI activity? A striking finding in
patients with MS who are initiated on interferon-␤
therapy is the rapidity of resolution of the gadolinium
(Gd)-enhancing activity on MRI.36 In contrast, Gdenhancing MRI activity is decreased more gradually in
patients on GA.37 Gd-enhancing MRI activity is correlated with lymphocyte infiltration and increase of
MMP levels leading to blood-brain barrier (BBB) disruption.38,39 The multiple ways by which interferon-␤
decreases lymphocyte infiltration, and especially its reduction of proteolytic MMP levels, likely accounts for
its rapid resolution of Gd-enhancing MRI activity (see
figure 3).
In contrast, by not having any direct action on
MMP or lymphocyte infiltration, this does not favor a
rapid resolution of Gd-enhancing MRI activity by
GA. It is important to point out that GA-reactive Th2
cells should have entered the CNS early in treatment to begin to achieve their effects within the CNS
(discussed below). Over the longer term, the resolu4
NEUROLOGY 59
September (2 of 2) 2002
tion of the Gd-enhancing MRI activity would be a
reflection of the activity of GA on elements within
the CNS, which then helps repair the BBB from
within the CNS (see figure 3). These observations
caution against the mere use of Gd-enhancing MRI
signatures to document the effectiveness of a particular therapy for MS. The lack of acute effects on the
BBB does not equate with lack of efficacy, if other
modes of action predominate for such drugs.
In summary, interferon-␤ exerts multiple actions
at the BBB to exclude leukocytes from entering the
CNS, but GA does not. This major differential may
help account for the finding that interferon-␤ rapidly
resolves Gd-enhancing MRI activity, while GA does
not (see figure 3).
Mechanisms of action of drugs within the
CNS. Bystander suppression as a mechanism for
GA within the CNS. By virtue of excluding cells
from entering the CNS parenchyma, and because
interferon-␤ itself is not thought to enter the CNS, it
seems prudent to state that interferon-␤ has no direct activity within the brain and spinal cord. Thus,
the resolution of CNS inflammation by interferon-␤
could be considered indirect, since this would be the
result of inhibiting the infiltration of inflammatory
cells into the CNS.
In contrast, GA-polarized Th2 cells enter the
CNS35 and, within the CNS, are thought to decrease
CNS inflammation by a phenomenon described as
bystander suppression. In this regard, GA-specific
Th2 cells within the CNS become reactivated by antigen presentation through cells that are likely microglia or macrophages that have infiltrated the
CNS. Here, the antigen that is presented by micro-
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Table Similarities and contrasts of the mechanisms of interferon␤ and GA in MS
Biology
Interferon-␤
GA
Antigen presentation
Decreased expression of MHC II
expression
Yes
No
Reduced level of costimulatory
molecules
Yes
No
Inhibition of clonal expansion of
autoreactive T cells
Yes
Yes
Increased apoptosis of autoreactive T
cells clear
Yes
Not
Decrease of proinflammatory
cytokines
Yes
Yes
Th1 to Th2 deviation
Not clear
Yes
Yes
No
Leukocyte trafficking across the BBB
Decreased expression of adhesion
molecules
Inhibition of chemokine expression
Yes
No
Inhibition of MMPs
Yes
No
Excludes leukocytes from entering
the CNS
Yes
No
Bystander suppression
No
Yes
Direct neuroprotection
Not clear
Possibly
Events within the CNS
GA ⫽ glatiramer acetate; MHC ⫽ major histocompatibility complex; BBB ⫽ blood-brain barrier; MMP ⫽ matrix metalloproteinase.
glia/macrophages is likely not GA, since this drug is
rapidly metabolized following administration and is
not thought to enter the CNS. There is evidence to
indicate that GA-specific T cells recognize a variety
of antigens presented by APC.40 For instance, GAspecific T cells from animal studies proliferate in
response to various myelin proteins in vitro;7 indeed,
GA was originally designed to simulate the structure
of MBP. Thus, it is likely that the presentation of
degraded myelin components by microglia or macrophages within the CNS leads to the reactivation of
GA-specific T cells. The expansion of these Th2 polarized cells within the CNS results in the release of
anti-inflammatory cytokines, which then impair the
expansion of myelin autoreactive T cells that are
within the CNS. This is bystander suppression. Indeed, the phenomenon of bystander suppression
means that GA may be potentially useful in other
autoimmune diseases where Th1 cells predominate.
Protective autoimmunity and GA. In contrast to
the commonly accepted idea that autoreactive T cells
produce the CNS pathology in MS, recent evidence
demonstrates that some autoreactive T cells have
neuroprotective functions. This was first demonstrated in an optic nerve crush model in rats, which
produced loss of retinal ganglion neurons. If animals
were injected with MBP-reactive T cells immediately
after the crush injury, which led to these cells accumulating in the injured optic nerve, the subsequent
loss of retinal ganglion neurons was attenuated.41
The neuroprotective effect of T cells has also been
observed after spinal cord injuries.42 These results
have generated much interest in the idea of protective autoimmunity, whereby autoreactive T cells protect against the loss of axons or neurons. Thus, it
may be disadvantageous to limit the entire T cell
immune response in the CNS following injury.
The mechanism(s) by which autoreactive T cells
alleviate injury is still unclear, but it has become
evident that T cells, B cells, and macrophages secrete
a variety of neurotrophic factors.43 Indeed, brainderived neurotrophic factor was localized by immunohistochemistry to inflammatory infiltrates in MS
lesions43 and in EAE.44 Thus, the increased availability
of neurotrophic factors resulting from the infiltration of
inflammatory cells may attenuate injury. Alternatively, neurotrophins have many beneficial immunoregulatory functions and this may favor a reduction of
the undesirable effects of CNS inflammation.45
It is obvious that much remains to be done to
define whether, when, and how autoreactive T cells
are beneficial or detrimental to CNS recovery. Where
myelin reactive T cells were used to alleviate neuronal loss after a traumatic injury to the optic nerve or
the spinal cord,41,44 symptoms of EAE appeared in
animals. It is unlikely that myelin reactive T cells
would be used to alleviate injury in MS, but can
other more benign T cell lines be used? Specifically,
does the generation of GA-specific T cells that enter
the CNS provide for neuroprotection? In this regard,
it is noteworthy that when rats were subjected to an
optic nerve crush, and then immediately injected
with GA-specific T cells, the number of surviving
retinal ganglion neurons after 2 weeks was higher in
treated animals compared to injured controls.46 More
recently, using a model where the intraocular injection of glutamate in mice destroyed retinal ganglion
neurons, the toxicity of glutamate was alleviated in
mice immunized with GA, but not with MBP or myelin oligodendrocyte glycoprotein.47 Collectively,
these results suggest that in patients with MS
treated with GA, the GA-reactive Th2 cells that enter the CNS have the potential to provide neuroprotection. Indeed, in an MRI study evaluating the
proportion of new MS lesions that evolved into ‘black
holes,’ which are thought to represent lesions where
severe tissue disruption has occurred, the proportion
was lower in GA-treated compared to placebo patients after 7 and 8 months of therapy.48
In summary, both interferon-␤ and GA decrease
CNS inflammation but by different means (see figure
3). Interferon-␤ excludes inflammatory leukocytes
from the CNS, whereas GA-reactive Th2 cells enter
the CNS to dampen neuroinflammation through bystander suppression. The presence of GA-reactive
cells within the CNS may confer protective autoimmunity and alleviate the loss of CNS tissue. It is
likely that interferon-␤ treatment also decreases
CNS neuronal and axonal loss, but the mechanism
for this would be indirect, i.e., by the exclusion of the
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largely pathogenic inflammatory cells that enter the
CNS, even at the expense of excluding some protective lymphocytes.
T1
Combination therapy? It is logical to ask whether
GA and interferon-␤ can be combined to increase their
effectiveness. Until the results of a formal combination
trial are available, the answer is not immediately apparent, and is dependent on what the pivotal mechanism of each drug would ultimately prove to be. Thus,
if the main mechanism of interferon-␤ and GA is to
decrease T cell proliferation and proinflammatory cytokine levels in the periphery, then the combination
treatment would suggest better efficacy, since both
have such actions albeit by different mechanisms. In
support, in vitro studies have shown that both drugs
have a greater effect on reducing the proliferation of
MBP-specific T cells than either alone.49 Conversely,
it is possible that interferon-␤ may inhibit the expansion of GA-reactive Th2 cells. Finally, if the main
target of GA is by having GA-reactive cells enter the
CNS to produce bystander suppression, then the
multiple effects of interferon-␤ on the BBB would
counteract the activity of GA by preventing GA Th2
cells access to the CNS. Until the pivotal mechanisms of interferon-␤ and GA in MS are precisely
identified, it would be prudent to await the results of
a formal combination trial of interferon-␤ and GA
(being conducted by Dr. Fred Lublin et al.).
What about other combinations? Antimitotic immunosuppressants, including cyclophosphamide and
mitoxantrone, may be rationally combined with
interferon-␤, as their simultaneous use may result in
a greater inhibition of the generation of autoreactive
cells. In contrast, the concurrent use of these antiproliferative agents with GA would likely impair the
expansion of GA-specific Th2 cells, thus negating the
efficacy of GA. Conceivably, cyclophosphamide and
mitoxantrone may be used prior to GA to eradicate
autoreactive Th1 cells; the subsequent introduction
of GA would expand GA-specific Th2 cells in a milieu
containing relatively few proinflammatory Th1 cells.
It should be apparent that both interferon-␤ and
GA are potent drugs that affect several stages of the
process that contribute to MS pathology. While both
ultimately lead to the reduction of a proinflammatory response in the periphery and within the CNS,
the mechanisms by which they do so are remarkably
distinct (table).
Acknowledgment
The author thanks Fiona Yong, who drew the figures for this
review and for all of the slide presentations, and his colleagues,
Fabrizio Giuliani and Jennifer Takahashi, for critically reading
through a draft of this manuscript.
References
1. Yong VW, Chabot S, Stuve O, Williams G. Interferon beta in
the treatment of multiple sclerosis: mechanisms of action.
Neurology 1998;51:682– 689.
2. Bar–Or A, Enedina ML, Oliveira EML, Anderson DE, Hafler
DA. Molecular pathogenesis of multiple sclerosis. J Neuroimmunol 1999;100:252–259.
6
NEUROLOGY 59
September (2 of 2) 2002
3. Martin R, Sturzebecher CS, McFarland HF. Immunotherapy
of multiple sclerosis: where are we? Where should we go? Nat
Immunol 2001;2:785–788.
4. O’Connor KC, Bar–Or A, Hafler DA. The neuroimmunology of
multiple sclerosis: possible roles of T and B lymphocytes in
immunopathogenesis. J Clin Immunol 2001;21:81–92.
5. Sela M, Teitelbaum D. Glatiramer acetate in the treatment of
multiple sclerosis. Expert Opin Pharmacother 2001;2:1149 –
1165.
6. Neuhaus O, Farina C, Wekerle H, Hohlfeld R. Mechanisms of
action of glatiramer acetate in multiple sclerosis. Neurology
2001;56:702–708.
7. Aharoni R, Teitelbaum D, Sela M, Arnon R. Copolymer 1
induces T cells of the T helper type 2 that crossreact with
myelin basic protein and suppress experimental autoimmune
encephalomyelitis. Proc Natl Acad Sci USA 1997;94:10821–
10826.
8. Hussien Y, Sanna A, Soderstrom M, Link H, Huang YM.
Glatiramer acetate and interferon-beta act on dendritic cells
in multiple sclerosis. J Neuroimmunol 2001;121:102–110.
9. Sharief MK, Semra YK, Seidi OA, Zoukos Y. Interferon-beta
therapy downregulates the anti-apoptosis protein FLIP in T
cells from patients with multiple sclerosis. J Neuroimmunol
2001;120:199 –207.
10. Zang YC, Yang D, Hong J, Tejada–Simon MV, Rivera VM,
Zhang JZ. Immunoregulation and blocking antibodies induced
by interferon beta treatment in MS. Neurology 2000;55:397– 404.
11. Aktas O, Ari N, Rieks M, et al. Multiple sclerosis: modulation
of apoptosis susceptibility by glatiramer acetate. Acta Neurol
Scand 2001;104:266 –270.
12. Rudick RA, Ransohoff RM, Lee JC, et al. In vivo effects of
interferon beta-1a on immunosuppressive cytokines in multiple sclerosis. Neurology 1998;50:1294 –1300.
13. Lunemann JD, Aktas O, Gniadek P, Zschenderlein R, Zipp F.
Downregulation of transforming growth factor-beta1 in
interferon-beta1a-treated MS patients. Neurology 2001;57:
1132–1140.
14. Gayo A, Mozo L, Suarez A, Tunon A, Lahoz C, Gutierrez C.
Long-term effect interferon-beta1b treatment on the spontaneous and induced expression of IL-10 and TGFbeta1 in MS
patients. J Neurol Sci 2000;179:43– 49.
15. Dayal AS, Jensen MA, Lledo A, Arnason BGW. Interferongamma-secreting cells in multiple sclerosis patients treated
with interferon beta-1b. Neurol 1995;45:2173–2177.
16. Wandinger KP, Sturzebecher CS, Bielekova B, et al. Complex
immunomodulatory effects of interferon-beta in multiple sclerosis include the upregulation of T helper 1-associated marker
genes. Ann Neurol 2001;50:349 –357.
17. Furlan R, Bergami A, Lang R, et al. Interferon-beta treatment
in multiple sclerosis patients decreases the number of circulating T cells producing interferon-gamma and interleukin-4.
J Neuroimmunol 2000;111:86 –92.
18. Karandikar NJ, Crawford MP, Yan X, et al. Glatiramer acetate
(Copaxone) therapy induced CD8⫹ T cell responses in patients
with multiple sclerosis. J Clin Invest 2002;109:641– 649.
19. Brenner T, Arnon R, Sela M, et al. Humoral and cellular immune responses to copolymer 1 in multiple sclerosis patients
treated with Copaxone. J Neuroimmunol 2001;115:152–160.
20. Trapp BD, Peterson J, Ransohoff RM, Rudick R, Mork S, Bo
L. Axonal transection in the lesions of multiple sclerosis.
N Engl J Med 1998;338:278 –285.
21. Balashov KE, Rottman JB, Weiner HL, Hancock WW. CCR5⫹
and CXCR3⫹ T cells are increased in multiple sclerosis and
their ligands MIP-1␣ and IP-10 are expressed in demyelinating lesions. Proc Natl Acad Sci USA 1999;96:6873– 6878.
22. Sorensen TL, Tani M, Jensen J, et al. Expression of specific
chemokines and chemokine receptors in the central nervous
system of multiple sclerosis patients. J Clin Invest 1999;103:
807– 815.
23. Yong VW, Power C, Forsyth P, Edwards DR. Metalloproteinases in biology and pathology of the nervous system. Nat Rev
Neurosci 2001;2:502–511.
24. Calabresi PA, Pelfrey CM, Tranquill LR, Maloni H, McFarland HF. VLA-4 expression on peripheral blood lymphocytes is
downregulated after treatment of multiple sclerosis with interferon beta. Neurology 1997;49:1111–1116.
25. Iarlori C, Reale M, Lugaresi A, et al. RANTES production and
expression is reduced in relapsing-remitting multiple sclerosis
balt4/nl-neurol/nl-neurol/nl1802/nl6349-02o kroenink Sⴝ7 6/26/02 12:22 Art:
26.
27.
28.
29.
30.
31.
32.
33.
34.
35.
36.
37.
patients treated with interferon-beta-1b. J Neuroimmunol
2000;107:100 –107.
Zang YC, Halder JB, Samanta AK, Hong J, Rivera VM, Zhang
JZ. Regulation of chemokine receptor CCR5 and production of
RANTES and MIP-1alpha by interferon-beta. J Neuroimmunol 2001;112:174 –180.
Stuve O, Dooley NP, Uhm JH, Antel JP, Williams G, Yong
VW. Interferon-␤ decreases the migration of T lymphocytes in
vitro: effects on matrix metalloproteinase-9. Ann Neurol 1996;
40:853– 863.
Leppert D, Waubant E, Burk MR, Oksenberg JR, Hauser SL.
Interferon beta-1b inhibits gelatinase secretion and in vivo migration of human T cells: a possible mechanism for treatment
efficacy in multiple sclerosis. Ann Neurol 1996;40:846– 852.
Trojano M, Avolio C, Liuzzi GM, et al. Changes of serum
sICAM-1 and MMP-9 induced by interferon-beta1b treatment
in relapsing-remitting MS. Neurology 1999;53:1402–1408.
Ozenci V, Kouwenhoven M, Teleshova N, Pashenkov M,
Fredrikson S, Link H. Multiple sclerosis: pro- and antiinflammatory cytokines and metalloproteinases are affected
differentially by treatment with interferon-beta. J Neuroimmunol 2000;108:236 –243.
Galboiz Y, Shapiro S, Lahat N, Rawashdeh H, Miller A. Matrix metalloproteinases and their tissue inhibitors as markers
of disease subtype and response to interferon-beta therapy in
relapsing and secondary-progressive multiple sclerosis patients. Ann Neurol 2001;50:443– 451.
Yu M, Nishiyama A, Trapp BD, Tuohy VK. Interferon-␤ inhibits progression of relapsing-remitting experimental autoimmune encephalomyelitis. J Neuroimmunol 1996;64:91–100.
Dufour A, Corsini E, Gelati M, Massa G, Tarcic N, Slamaggi
A. In vitro glatiramer acetate treatment of brain endothelium
does not reduce adhesion phenomena. Ann Neurol 2000;47:
680 – 681.
Li QQ, Bever CT. Glatiramer acetate blocks interleukin-1dependent nuclear factor-kappaB activation and RANTES expression in human U-251 MG astroglial cells. Brain Res Mol
Brain Res 2001;87:48 – 60.
Aharoni R, Teitelbaum D, Leitner O, Meshorer A, Sela M,
Arnon R. Specific Th2 cells accumulate in the central nervous
system of mice protected against experimental autoimmune
encephalomyelitis by copolymer 1, Proc Natl Acad Sci USA
2000;97:11472–11477.
Stone LA, Frank JA, Albert PS, et al. Characterization of MRI
response to treatment with interferon beta-1b: contrastenhancing MRI lesion frequency as a primary outcome measure. Neurology 1997;49:862– 869.
Comi G, Filippi M, Wolinsky JS. European/Canadian multicenter, double-blind, randomized, placebo-controlled study of
38.
39.
40.
41.
42.
43.
44.
45.
46.
47.
48.
49.
Input-djh(v)
the effects of glatiramer acetate on magnetic resonance imaging–measured disease activity and burden in patients with
relapsing multiple sclerosis. European/Canadian Glatiramer
Acetate Study Group. Ann Neurol 2001;49:290 –297.
Rosenberg GA, Dencoff JE, Correa N, Reiners M, Ford CC.
Effects of steroids on CSF matrix metalloproteinases in multiple sclerosis: relation to blood-brain barrier injury. Neurology
1996;46:1626 –1632.
Waubant E, Goodkin DE, Gee L, et al. Serum MMP-9 and
TIMP-1 levels are related to MRI activity in relapsing multiple sclerosis. Neurology 1999;53:1397–1401.
Duda PW, Schmied MC, Cook SL, Krieger JI, Hafler DA.
Glatiramer acetate (Copaxone) induces degenerate, Th2polarized immune responses in patients with multiple sclerosis. J Clin Invest 2000;105:967–976.
Moalem G, Leibowitz–Amit R, Yoles E, Mor F, Cohen IR,
Schwartz M. Autoimmune T cells protect neurons from secondary degeneration after central nervous system axotomy.
Nat Med 1999;5:49 –55.
Hauben E, Butovsky O, Nevo U, et al. Passive or active immunization with myelin basic protein promotes recovery from
spinal cord contusion. J Neurosci 2000;20:6421– 6430.
Kerschensteiner M, Gallmeier E, Behrens L, et al. Activated
human T cells, B cells, and monocytes produce brain-derived
neurotrophic factor in vitro and in inflammatory brain lesions:
a neuroprotective role of inflammation? J Exp Med 1999;189:
865– 870.
Hammarberg H, Lidman O, Lundberg C, et al. Neuroprotection by encephalomyelitis: rescue of mechanically injured neurons and neurotrophin production by CNS-infiltrating T and
natural killer cells. J Neurosci 2000;20:5283–5291.
Hohlfeld R, Kerschensteiner M, Stadelmann C, Lassmann H,
Wekerle H. The neuroprotective effect of inflammation: implications for the therapy of multiple sclerosis. J Neuroimmunol
2000;107:161–166.
Kipnis J, Yoles E, Porat Z, et al. T cell immunity to copolymer
1 confers neuroprotection on the damaged optic nerve: possible therapy for optic neuropathies. Proc Natl Acad Sci USA
2000;97:7446 –7451.
Schori H, Kipnis J, Yoles E, et al. Vaccination for protection of
retinal ganglion cells against death from glutamate cytotoxicity and ocular hypertension: implications for glaucoma. Proc
Natl Acad Sci USA 2001;98:3398 –3403.
Filippi M, Rovaris M, Rocca MA, Sormani MP, Wolinsky JS,
Comi G. Glatiramer acetate reduces the proportion of new MS
lesions evolving into “black holes”. Neurology 2001;57:731–733.
Milo R, Panitch H. Additive effects of copolymer-1 and interferon beta-1b on the immune response to myelin basic protein.
J Neuroimmunol 1995;61:185–193.
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