J C E M
O N L I N E
B r i e f
R e p o r t — E n d o c r i n e
R e s e a r c h
Interleukin 1B Variant -1473G/C (rs1143623)
Influences Triglyceride and Interleukin 6 Metabolism
Javier Delgado-Lista,* Antonio Garcia-Rios,* Pablo Perez-Martinez, Juan Solivera,
Elena M. Yubero-Serrano, Francisco Fuentes, Laurence D. Parnell, Jian Shen,
Purificacion Gomez, Yolanda Jimenez-Gomez, Maria J. Gomez-Luna,
Carmen Marin, Sarah E. Belisle, Fernando Rodriguez-Cantalejo, Simin N. Meydani,
Jose M. Ordovas, Francisco Perez-Jimenez, and Jose Lopez-Miranda
Lipids and Atherosclerosis Unit (J.D.-L., A.G.-R., P.P.-M., E.M.Y.-S., F.F., P.G., Y.J.-G., M.J.G.-L., C.M.,
F.P.-J., J.L.-M.), Instituto Maimonides de Investigación Biomedica de Cordoba/Hospital Universitario
Reina Sofía/Universidad de Córdoba and CIBER Fisiopatología Obesidad y Nutrición, Instituto de Salud
Carlos III, 14004 Cordoba, Spain; Neurosurgery Unit (J.S.), Hospital Universitario Reina Sofía, 14004
Cordoba, Spain; Nutrition and Genomics (L.D.P., J.S., J.M.O.), and Nutritional Immunology Laboratory
(S.E.B., S.N.M.), Jean Mayer United States Department of Agriculture Human Nutrition Research Center
on Aging, Tufts University, Boston, Massachusetts 02111; Biochemical Laboratory (F.R.-C.), Hospital
Universitario Reina Sofía, 14004 Cordoba, Spain; and Department of Epidemiology and Population
Genetics (J.M.O.), Centro Nacional de Investigaciones Cardiovasculares, 28029 Madrid, Spain
Context: IL1b (IL1B or IL1␤), a key modulator of the immune response, exerts its functions mainly
via IL6 regulation. Fatty meals cause transient hypertriglyceridemia and are considered to be
proinflammatory, but the extent of these responses shows high interindividual susceptibility.
Objective: We evaluated the influence of a genetic variant located in the promoter region of IL1B
(-1473G/C) on fasting and postprandial lipids and IL6.
Design, Setting, and Participants: A total of 477 people over age 65 yr were genotyped for IL1B
-1473G/C, and we evaluated fasting lipids depending on genotype. Then, 88 healthy young men
were also genotyped and were fed a saturated fatty acid-rich meal. Serial blood samples were
drawn for 11 h after the meal, and lipid fractions and IL6 were assayed.
Main Outcome and Interventions: Fasting lipids were studied in the aged persons. Fasting and
postprandial measurements of lipids and IL6 were performed in the healthy young men.
Results: In the aged persons, CC subjects (minor allele homozygotes) showed higher triglyceride
(P ⫽ 0.002) and cholesterol (P ⫽ 0.011) levels. Healthy young male carriers of the minor C allele
showed higher postprandial triglycerides (P ⫽ 0.037), and those carried into large triglyceride-rich
lipoproteins (P ⫽ 0.004). In addition, they showed higher postprandial IL6 concentrations (P ⫽
0.008).
Conclusions: Our work shows that inflammatory genes may regulate fasting and postprandial
lipids because the carriers of the minor allele of an IL gene variant have altered lipid metabolism.
To reinforce these gene-phenotype findings, IL6 (the natural effector of IL1B) was increased in
these persons. (J Clin Endocrinol Metab 96: E816 –E820, 2011)
ISSN Print 0021-972X ISSN Online 1945-7197
Printed in U.S.A.
Copyright © 2011 by The Endocrine Society
doi: 10.1210/jc.2010-2455 Received October 18, 2010. Accepted January 19, 2011.
First Published Online February 9, 2011
*J.D.-L. and A.G.-R. are equal contributors of this article.
Abbreviations: CHOL, Cholesterol; SNP, single nucleotide polymorphism; TG, triglyceride(s); TRL, TG-rich lipoprotein(s).
For editorial see page 1279
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J Clin Endocrinol Metab, May 2011, 96(5):E816 –E820
J Clin Endocrinol Metab, May 2011, 96(5):E816 –E820
n the modern concept of atherosclerosis, inflammation
is an essential mechanism both in the origin and the
development of the disease, involving both inflammatory
cells (mainly mononuclear cells) and cytokines of several
origins (1, 2). IL1B is an IL that is promoted in macrophage
activation scenarios such as those of inflammatory/infectious states or chronic macrophage activation (3). Furthermore, IL1B has been implicated in atherosclerosis,
controlling macrophage internalization to the subendothelial space where the cells transform into foam cells (2).
IL1B exerts its primary proinflammatory effects by
stimulating the formation of its main effector, IL6, which
drives the inflammation cascade (4). The biological significance of IL1B and IL6 in atherosclerosis is supported
by experimental and epidemiological evidence. Both IL1B
and IL6 gene transcripts are expressed in human atheroma
(5). IL6, the final effector of IL1B, is directly correlated
with a greater risk for cardiovascular disease and with a
worse prognosis after coronary events (6). Furthermore,
inhibiting IL1B reduces heart failure after acute myocardial infarct (7). Moreover, IL1 and IL6 also have an important impact on lipid metabolism. In fact, patients with
chronic inflammatory diseases often display proatherogenic lipid profiles (3, 8).
The postprandial state after a fatty meal, especially
when the meal is rich in saturated fatty acids, induces a
“physiological” inflammatory response that includes IL6
(9, 10). Furthermore, it has been shown that pronounced
postprandial hypertriglyceridemia may play a pivotal role
in the control of atherogenesis (11). This postprandial
state is subjected to external (mainly dietary) and internal
regulation. Furthermore, genetic modulation has been
identified as one of the key contributors to the extent of the
postprandial lipemia (11, 12).
Some IL1B gene variants have been associated with
increased cardiovascular risk (13), but to date there is no
solid evidence that satisfactorily explains the underlying
mechanisms. In this study, we explored the effects of a
common variant of IL1B in the postprandial state after a
saturated, rich fatty meal—a situation that promotes IL
metabolism.
I
Subjects and Methods
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no neoplastic diseases at recruitment, and signed an informed
consent.
Healthy young men cohort
The cohort consisted of 88 healthy men aged 18 to 33 yr from
Cordoba, Spain, who signed an informed consent. A high-fat
meal test based on saturated fatty acids was performed and was
followed by 11 h of postmeal sample collection, as published
elsewhere (15). IL6 plasma measurements were done at fasting
and at 4 h. Sample size was calculated based on data obtained from
a previous study (16): mean difference expected ⫽ 1.5, SD ⫽ 0.9,
power ⫽ 80%, P ⱕ 0.05, requiring at least six persons in each
genotype group.
Each study was approved by the Ethics Committee of the
centers in which the study was carried out. Detailed information
about the methodology of both studies has been published elsewhere (14, 15).
Biochemical measures
DNA amplification and genotyping
TaqMan assays, allele discrimination of PCR products, and
collection of fluorescence data by the 7900 Sequence Detection
System (Applied Biosystems, Foster City, CA) were performed as
previously described (15). Hardy-Weinberg equilibrium was
tested by Fisher’s exact test.
Lipoprotein separation and biochemical analysis
Large and small triglyceride (TG)-rich lipoproteins (TRL)
were manually extracted after centrifugation in subdued light,
and samples were stored at ⫺70 C until analyzed. Cholesterol
(CHOL), TG, apolipoprotein A1, apolipoprotein B, high-density
lipoprotein-CHOL, and low-density lipoprotein-CHOL were
measured in the hospital laboratory with standard methods and
were performed as published (15, 16). Plasma IL6 concentration
was determined by an ELISA kit (Quantikine IL6 ELISA kit;
R&D Systems, Inc., Minneapolis, MN).
Statistical analysis
For the elderly cohort, association of the single nucleotide
polymorphism (SNP) with TG concentration was made by univariate ANOVA, with age, sex, body mass index, and presence
of diabetes mellitus as covariates. We excluded from the analysis
those subjects that had their TG levels above the mean plus 3 SD
values. Statistical methods employed for the analysis of the cohort of healthy men are comparable to those that we have published previously with regard to the gene-postprandial state interaction (15) and recently revised (12), using one-way ANOVA
for area under the curve and repeated-measures ANOVA. We
included the SNP as an independent factor and body mass index
and age as covariates. A P value of less than 0.05 was considered
significant. Data presented are mean ⫾ SE. We used SPSS 18.0 for
Windows (SPSS Inc., Chicago, IL).
Subjects and study design
Elderly cohort
Data for the present study come from preinterventional samples from 461 participants of a vitamin E intervention trial from
Boston, Massachusetts (14). Briefly, the participants, mostly
White/non-Hispanics (95%), were recruited from long-term care
facilities, had life expectancy greater than 6 months, presented
Results
There was no departure from Hardy-Weinberg equilibrium (P ⬎ 0.40 in both samples). In the elderly cohort, we
found a greater plasma concentration of TG and CHOL in
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Delgado-Lista et al.
IL1B -1473G/C, Lipids, and Inflammation
homozygotes for the minor allele vs. the other two genotypes (for TG—CC 180.8 ⫾ 12.1, CG 142.2 ⫾ 4.9, and
GG 140 ⫾ 4.0 mg/dl, P ⫽ 0.002; for CHOL—CC 218.9 ⫾
7.9, CG 193.1 ⫾ 3.3, and GG 197.1 ⫾ 2.6 mg/dl, P ⫽
0.011). In the healthy men cohort (baseline characteristics are shown in Supplemental Table 1, published on
The Endocrine Society’s Journals Online web site at
http://jcem.endojournals.org), we found differences in the
postprandial measurements (summarized in Figs. 1 and 2
and Supplemental Table 2). Carriers of the minor C allele
of -1473G/C showed a higher area under the curve of total
TG (P ⫽ 0.037) and large-TRL TG (P ⫽ 0.004) compared
with homozygotes for the major G allele (Supplemental
Table 2). In the repeated-measures ANOVA, differences
were evident in the third to sixth hours for total TG and at
h 0, 2, 3, 4, 5, and 6 for the large-TRL TG (Fig. 1). We
found no differences in the other lipid parameters. IL6
values were dependent on the -1476G/C genotype (P ⫽
0.005), with higher values in the GC/CC group. These
differences were primarily due to the postprandial measurements (GC/CC 5.62 ⫾ 0.62 vs. GG 2.96 ⫾ 0.31 pg/ml;
P ⫽ 0.008), and a similar trend was found after the over-
FIG. 1. Evolution of TG (A) and large-TRL TG concentrations (B)
depending on -1473G/C (rs1143623) genotype. Data are expressed as
means ⫾ SE. *, P ⬍ 0.05.
J Clin Endocrinol Metab, May 2011, 96(5):E816 –E820
FIG. 2. Fasting and postprandial measures of IL6 depending on IL1B
genotype. Data are expressed as means ⫾ SE. *, P ⬍ 0.05 GG vs.
GC/CC.
night fasting (GC/CC 1.76 ⫾ 0.41 vs. GG 0.99 ⫾ 0.29
pg/ml; P ⫽ 0.083) (Fig. 2).
Discussion
Our results show that healthy young male carriers of the
minor C allele of IL1B SNP -1473G/C (rs1143623) have
higher postprandial lipemia than homozygotes for the major allele. We also show how this IL1B variant affects
inflammation by influencing IL6 concentrations postprandially. The postprandial state, especially after a meal
rich in saturated fatty acids, induces inflammation primarily by monocyte/macrophage activation (9, 10, 16)
and increased production of other proinflammatory, procoagulant species (1–3). An enlargement of postprandial
inflammation, as proposed by the augmented increase in
plasma IL6 seen in carriers of the -1473G/C minor allele,
would theoretically confer a physiological disadvantage to
these individuals by promoting atherosclerosis development via increased inflammation. Furthermore, carriers of
the minor allele also exhibit an extended postprandial hypertriglyceridemia, which is also associated with accelerated atherosclerosis development. All of these results may
be due to a combination of partial impairment of lipoprotein lipase to hydrolyze the TG contained in the TRL by
either increased TRL particle formation or lower clearance, as previously proposed, and by an increase in adipocyte lipolysis and altered very low-density lipoprotein
metabolism, which also has been reported for situations
with increased IL6 (3, 17). Supporting our findings, we
have reported previously other harmful effects of this
polymorphism. Homozygotes for the minor allele had a
higher risk for high blood pressure (P ⬍ 0.05) and a trend
toward higher abdominal obesity and metabolic syndrome (P ⫽ 0.078) (17). Apart from the postprandial find-
J Clin Endocrinol Metab, May 2011, 96(5):E816 –E820
ings we report here, this SNP likely affects fasting lipids in
general elderly populations (age, ⬎65 yr) by provoking
higher fasting CHOL and TG concentrations. To merge
our two main findings, we hypothesize that young, normolipemic men only show the effects of the -1473 SNP in
the postprandial state due to their “healthier, more resilient” background and younger age.
The experimental design does not allow us to identify
the precise molecular mechanisms underlying our findings. However, previous knowledge demonstrates that the
G allele of IL1B -1473G/C had decreased binding to nuclear extract of human monocytes (18) based on EMSA,
suggesting weaker promoter activity (or increased activity
for the C allele), which may shift gene transcription of C
carriers in response to a proinflammatory stimulus, such
as the postprandial state. Further computational analysis
proposed that this SNP is functional with allele-specific
participation of GATA-family transcription factors in regulating IL1B expression (18, 19). The increased transcriptional rate of IL1B may confer to this population additional biological disadvantages beyond lipid metabolism.
In this sense, it has been reported recently that an artificial
IL1B blockade with an artificial antagonist (anakinra) has
favorable effects on several inflammatory diseases, such as
gout, but also type II diabetes mellitus metabolic control,
or, even, in multiple myeloma (3, 20).
In conclusion, we observed that carriers of the minor
allele of a common SNP in IL1B (-1473G/C, rs1143623)
have an exaggerated postprandial lipemia accompanied
by an increased postprandial IL6 production, and that
elderly homozygotes for the rare allele have increased levels of fasting TG. The combination of increased TG and
IL6 levels allows us to hypothesize that these patients may
have a higher inflammatory status and may overrespond
to the proinflammatory stimulus that represents a fatty
meal.
Acknowledgments
CIBER Fisiopatologia de la Obesidad y Nutricion is an initiative
of Instituto de Salud Carlos III, government of Spain.
Address all correspondence and requests for reprints to:
Jose Lopez-Miranda, Servicio de Medicina Interna, Unidad de
Lípidos y Arteriosclerosis, Hospital Universitario Reina Sofia,
Edificio de Consultas Externas, 2 planta, 14004 Córdoba.
Spain. E-mail: [email protected].
This work was supported by Proyectos de Investigación,
Junta de Andalucia (PI-0252/2009, to J.D.-L.); Consejeria de
Innovación, Proyectos de Investigación de Excelencia Junta de
Andalucia (AGR 05/00922, to F.P.-J.; and P06-CTS-01425, to
J.L.-M.); Ministerio de Educación y Ciencia (AGL-2006-01979/
ALI, to J.L.-M.); National Institutes of Health (NIH) Grants R01
DK075030 and R01 HL054776 and U.S. Department of Agri-
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culture (USDA) Grant 58-1950-9-001 (to J.M.O.); NIH Grant
5R01-AG013975 and USDA Grant 58-1950-7-707 (to S.N.M.);
a grant for the preparation of study capsules from Hoffmann-La
Roche Inc.; and a DSM Nutritional Products, Inc. scholarship.
The study was also supported by Hebrew Rehabilitation Center for Aged/Harvard Research Nursing Home Grant PO1
AG004390.
Disclosure Summary: None of the authors declare any conflicts of interest regarding the present document.
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