Genetic variants within the interleukin-1 gene cluster, and risk of incident myocardial infarction, and ischemic stroke: a nested case-control approach

A Variant of IL1B Is Associated with the Risk and Blood Lipid Levels of Myocardial Infarction in Eastern Chinese Individuals

In this study, we determined to interpret the effects of the interleukin (IL)1B gene rs1143634 C/T polymorphism on myocardial infarction (MI) risk. This study, conducted in a Chinese Han population, recruited 369 MI patients and 465 controls. The variant of IL1B gene (rs1143634 C/T polymorphism) was genotyped by PCR-RFLP method. In this study, a significant link was shown between the IL1B rs1143634 C/T polymorphism and MI risk. We found that the IL1B rs1143634 C/T polymorphism enhanced the risk of MI in this population. Subgroup analysis detected that the IL1B rs1143634 C/T polymorphism associated with MI susceptibility in males, smokers, and individuals with diabetes mellitus. In addition, the IL1B rs1143634 C/T polymorphism was related with the levels of blood lipids including low-density lipoprotein (LDL), and total cholesterol (TC). This study uncovers that the IL1B rs1143634 C/T polymorphism may associate with the risk and blood lipid levels of MI in an Eastern Chinese Han population.Abbreviations: MI: myocardial infarction; IL-1: Interleukin-1; SNP: single nucleotide polymorphism; BMI: Body Mass Index; HDL: high-density lipoprotein; TC: total cholesterol; TG: triglyceride; LDL: low-density lipoprotein; PCR: polymerase chain reaction; 95% CI: 95% confidence interval; OR: odds ratio.

Association between IL-1β + 3954C/T polymorphism and myocardial infarction risk: A meta-analysis

BACKGROUND

Many studies have reported that the IL-1β + 3954C/T polymorphism (rs1143634) is related to myocardial infarction (MI). To classify the association between IL-1β + 3954C/T and MI susceptibility, we performed a meta-analysis.

METHODS

We retrieved relevant literature from electronic databases (Embase, PubMed, Cochrane, and Web of Science). Pooled odds ratios (ORs) and 95% confidence intervals (95% CIs) were calculated with a fixed effect model or a random effect model. Sensitivity analysis and publication bias results are also presented.

RESULTS

Nine eligible studies (2299 controls and 2203 cases) were included. The pooled results showed a significant relationship between MI and IL-1β + 3954C/T in an allelic comparison (T vs C: OR = 1.13, 95% CI 1.02-1.25, I = 0%, PH = .448) and in a dominant model (TC + TT vs CC: OR = 1.15, 95% CI 1.02-1.30, I = 0%, PH = .880). Ethnic subgroup analysis showed similar results in Caucasian populations: an allelic comparison (T vs C: OR = 1.16, 95% CI 1.04-1.29, I = 0%, PH = .701), homozygote model (TT vs CC: OR = 1.36, 95% CI 1.04-1.79, I = 0%, PH = .673), and dominant model (TC + TT vs CC: OR = 1.17, 95% CI 1.02-1.33, I = 0%, PH = .851). In addition, similar effects remained in subgroups analyses of high-quality studies and PCR-RFLP (restriction fragment length polymorphism) data.

CONCLUSION

Our meta-analysis proved that IL-1β + 3954C/T is associated with MI susceptibility, especially among Caucasian populations.

Polymorphisms in the IL-1 gene cluster influence systemic inflammation in patients at risk for acute-on-chronic liver failure

Acute-on-chronic liver failure (ACLF) in cirrhosis is an increasingly recognized syndrome characterized by acute decompensation, organ failure(s) and high short-term mortality. Recent findings suggest that an overexuberant systemic inflammation plays a primary role in ACLF progression. In this study, we examined whether genetic factors shape systemic immune responses in patients with decompensated cirrhosis. Six single-nucleotide polymorphisms (SNPs) in inflammation-related genes (interleukin [IL]-1 beta [IL-1β], rs1143623; IL-1 receptor antagonist [IL-1ra], rs4251961; IL-10, rs1800871; suppressor of cytokine signaling-3, rs4969170; nucleotide-binding oligomerization domain-containing protein 2, rs3135500; and chemerin chemokine-like receptor 1, rs1878022) were genotyped in 279 patients with cirrhosis with (n = 178) and without (n = 101) ACLF from the CANONIC study of the CLIF consortium. Among these SNPs, we identified two polymorphisms belonging to the IL-1 gene cluster (IL-1β and IL-1ra) in strong association with ACLF. Both SNPs were protective against ACLF; IL-1β (odds ratio [OR], 0.34, 95% confidence interval [CI], 0.13-0.89; P < 0.05) and IL-1ra (OR, 0.58; 95% CI, 0.35-0.95; P < 0.05) under the recessive and overdominant inheritance models, respectively. These protective SNPs translated into reduced circulating levels of IL-1β, IL-1α, IL-6, granulocyte-colony stimulating factor, granulocyte-macrophage colony-stimulating factor, and C-reactive protein at enrollment as well as after 7-14 days of admission. These findings were confirmed in vitro in leukocytes incubated with plasma from patients with decompensated cirrhosis carrying the protective SNP genotypes. Notably, a higher frequency of the protective genotypes was observed in patients without (80%) than in those with (20%) ACLF. Consistently, patients carrying the combined protective genotypes showed a lower 28-day mortality rate.

CONCLUSION

These data identify two common functional polymorphisms in the IL-1 gene cluster, which are associated with the inflammatory process related to development of ACLF. (Hepatology 2017;65:202-216).

Association between genetic polymorphisms of interleukins and cerebral infarction risk: a meta-analysis

Interleukins (ILs) are the most typical inflammatory and immunoregulatory cytokines. Evidences have shown that polymorphisms in ILs are associated with cerebral infarction risk. However, the results remain inconclusive. The present study was to evaluate the role of ILs polymorphisms in cerebral infarction susceptibility. Relevant case-control studies published between January 2000 and December 2015 were searched and retrieved from the electronic databases of Web of Science, PubMed, Embase and the Chinese Biomedical Database. The odds ratio (OR) with its 95% confidence interval (CI) were employed to calculate the strength of association. A total of 55 articles including 12619 cerebral infarction patients and 14436 controls were screened out. Four ILs (IL-1, IL-6, IL-10 and IL-18) contained nine single nucleotide polymorphisms (SNPs; IL-1α -899C/T, IL-1β -511C/T and IL-1β +3953C/T; IL-6 -174G/C and -572C/G; IL-10 -819C/T and -1082A/G; IL-18 -607C/A and -137G/C). Our result showed that IL-1α -899C/T and IL-18 -607C/A (under all the genetic models), and IL-6 -572C/G (under the allelic model, heterogeneity model and dominant model) were associated with increased the risk of cerebral infarction (P<0.05). Subgroup analysis by ethnicity showed that IL-6 -174G/C polymorphism (under all the five models) and IL-10 -1082A/G polymorphism (under the allelic model and heterologous model) were significantly associated with increased the cerebral infarction risk in Asians. Other genetic polymorphisms were not related with cerebral infarction susceptibility under any genetic models. In conclusion, IL-1α -899C/T, IL-6 -572C/G and IL-18 -607C/A might be risk factors for cerebral infarction development. Further studies with well-designed and large sample size are still required.

Association of IL-1β +3953 C and HLA-DRB1*15 with Coronary Artery and Rheumatic Heart Diseases in South India

Among the various candidate genes predisposing for cardiovascular diseases, HLA-DRB1* and IL-1β +3953C/T alleles have been implicated repeatedly. To test these in South India, we carried out a case control study of 323 Coronary Artery Disease (CAD) patients, 56 Rheumatic Heart Disease (RHD) patients and 254 endemic controls. The polymorphisms were studied by PCR - SSP and ARMS-PCR methods and results analyzed for various clinical and demographic parameters. In CAD, HLA-DRB1*14 allele showed significant predisposition (OR: 2.19; 95% CI: 1.04-4.58; p value=0.023), particularly in male patients (OR: 4.07; 95% CI: 1.20-13.81; p value=0.01) and further in males with Triple Vessel Disease (OR: 5.49; 95% CI: 1.45-20.60; p value=0.007). On the other hand, HLA-DRB1*15 predisposed for RHD (OR: 3.56; 95% CI: 1.87-6.78; p value=0.001) in both the genders. Population stratification showed this higher risk association in Vanniyar caste (OR: 5.00; 95% CI: 1.27-19.59; p value=0.022). Among the IL1-β +3953C/T polymorphism, the ancestral allele 'C' showed a significant high risk association with CAD (OR: 1.83; 95% CI: 1.24-2.70; p value=0.001), particularly in Mudaliar (OR: 6.07; 95% CI: 1.77-20.74; p value=0.003; AF=0.7) and Vanniyar castes (OR: 3.67; 95% CI: 0.92-14.57; p value=0.05; AF=0.660). Two different cardiac ailments studied, RHD & CAD thus showed varied associations in this South Indian cohorts. RHD having an infectious aetiology shared a HLA-DRB1*15 high risk association, while HLA-DRB1*14 and IL-1β +3953C predisposed for CAD, an inflammatory disorder, reiterating the diverse genetic predisposition of the two cardiac ailments studied.

Genetic association between inflammatory genes (IL-1α, CD14, LGALS2, PSMA6) and risk of ischemic stroke: A meta-analysis

BACKGROUND

Sequence variations in genes involved in inflammatory system are known to contribute to the risk of cerebrovascular diseases (CVD) including stroke. Very few number of studies have been published in the context of the association between Interleukin-1α(IL-1α), CD14 cell surface glycoprotein (CD14), Galectin-2-encoding gene (LGALS2)and proteasome subunit type 6 (PSMA6) gene polymorphisms with susceptibility to ischemic stroke (IS).

OBJECTIVE

The present meta-analysis aimed to provide a comprehensive account of the association between IL-1α (-C889T and -C511T), CD14 (-C159T), LGALS2 (-C3279T) and PSMA6 (-C8G) gene polymorphisms and susceptibility to IS.

METHODS

A literature search for eligible genetic studies published before August 31, 2015 was conducted in the PubMed, Medline, EMBASE, OVID, and Google Scholar databases. Fixed or random effects models were used to estimate the Pooled Odds ratio (OR) and 95% confidence interval (CI) using RevMan 5.3 software.

RESULTS

Total 21 studies were included in our meta-analysis. No significant association was observed between IL-1α (-C889T) [OR = 1.18, 95% CI: 0.67-2.08, P = 0.58], IL-1α (-C511T) [OR = 0.95, 95% CI: 0.66-1.37, P = 0.77], LGALS2(-C2379T) [OR = 0.29, 95% CI: 0.02-4.26, P = 0.37] and CD14 (-C260T) [OR = 0.93, 95% CI: 0.77-1.11, P = 0. 42] gene polymorphisms and risk of IS. However, protective level of association was observed between PSMA6 (-C8G) gene polymorphism and susceptibility to IS under the recessive model [OR = 0.25, 95% CI: 0.08-0.72, P = 0.01].

CONCLUSION

Our meta-analysis shows that IL-1α (-C889T and -C511T), CD14 (-C159T), LGALS2 (-C3279T) and gene polymorphisms are not significantly associated with the risk of IS while PSMA6 (-C8G) gene polymorphism may play a protective role with the susceptibility of IS. Further prospective large epidemiological studies are needed to confirm these findings in different populations.

Interleukin-1 Gene Cluster Polymorphisms and Their Association with Coronary Artery Disease: Separate Evidences from the Largest Case-Control Study amongst North Indians and an Updated Meta-Analysis

Several researchers have reported significant association of numerous single nucleotide polymorphisms (SNPs) residing in the interleukin-1 (IL-1) gene cluster with coronary artery disease (CAD). However, their association status amongst North Indian ancestry (NIA) have never been systematically assessed. Despite a published meta-analysis on this subject, their association status worldwide as well as amongst different major ancestral subgroups still remains unclear. We therefore decided to prospectively test the association of 11 IL-1 gene cluster SNPs with CAD, vide a case-control study amongst a cohort of NIA and attempted to validate our results with the help of an updated meta-analysis of all relevant published association studies. Included studies were segregated into ancestral subgroups and association statuses for each subgroup were determined. A total of 323 cases and 400 healthy, age and sex matched controls belonging to NIA were prospectively enrolled and subsequently genotyped for 11 selected IL-1 gene cluster SNPs. Although results for none of the evaluated IL-1 gene cluster SNPs reached the adjusted level of significance (p<0.0045), clear trends of association were seen for IL1B -511 C>T and IL1RN 86bp VNTR in several of the constructed genetic models (p range = 0.01–0.044 and 0.005–0.034 respectively). The presence of >1, ‘T’ (minor) allele of IL1B -511 C>T in a genotype seemed to provide protection against CAD (OR = 0.62, p = 0.044), while the presence of >1, ‘C’ (major) allele seemed to increase the risk of CAD (OR = 1.36, p = 0.041). The minor allele (allele 2) of IL1RN 86bp VNTR and its homozygous genotype (2/2 genotype) also seemed to carry an increased risk for CAD (OR = 1.62, p = 0.005 and OR = 2.25, p = 0.031 respectively). On the other hand, several haplotype combinations constructed out of IL1B and IL1RN gene variants clearly showed statistically significant associations with CAD (p<0.0045). Our meta-analysis was conducted for 8 previously assessed IL-1 SNPs. We included 53 different studies which involved a total sample of 26,210 (13,982 cases and 12,228 controls). Our pooled results concurred with the findings of our case-control study and was not able to deduce any statistically significant associations for any of the 8 studied SNPs (p>0.05). Subgroup analysis, however, yielded interesting results, where significant differences in association statuses were seen for IL1A +4845 G>T, IL1B -511 C>T, IL1RN 86bp VNTR and IL1RN +8006 T>C for select ancestral subgroups. The hints of associations deduced for subjects belonging to NIA in our case-control study for both IL1B -511 C>T and IL1RN 86bp VNTR were duly validated vide significant p values seen for NIA in all three genetic models (OR range = 0.62–0.76, p range = 0.01–0.04 and OR range = 1.51–2.25, p range = 0.004–0.04 respectively). On the other hand, Mixed Ancestry (MA) subgroup carrying IL1B -511 C>T, IL1RN 86bp VNTR or IL1RN +8006 T>C polymorphisms seemed to enjoy significant protection against CAD. A few other ancestral subgroups also demonstrated significant associations for a few of the studied SNPs vide one of the three genetic models. Clinical interpretation of derived results is however recommended.

The association between three promoter polymorphisms of IL-1 and stroke: a meta-analysis

AIM

The association between Interleukin-1 (IL-1) gene polymorphism and stroke remains controversial. The present study was designed to clarify this relationship through a pooled analysis of the numerous epidemiological studies focusing on this association.

METHODS

Published data addressing the association between polymorphism of the IL-1 gene and stroke were selected from electronic databases. A total of 21 studies from 19 publications including 5280 stroke patients and 5699 controls were included in this meta-analysis which detect whether IL-1α-889C/T, IL-1β-511C/T and IL-1 RN polymorphism were associated with stroke susceptibility.

RESULT

The combined results of overall analysis revealed that there was a significant association between IL-1α-889C/T polymorphism and stroke (allele model: OR = 1.39, 95% CI = 1.14-1.68, P < 0.001; recessive model: OR = 1.56, 95% CI = 1.27-1.90, P < 0.001; dominant model: OR = 1.45, 95% CI = 1.13-1.87, P = 0.004; additive model: OR = 1.70, 95% CI = 1.37-2.10, P < 0.001). On a subgroup analysis by ethnicity of study population, significant association was found in Asians (allele model: OR = 1.25 95% CI = 1.12-1.39, P < 0.001; recessive model: OR = 1.36, 95% CI = 1.09-1.69, P = 0.007; dominant model: OR = 1.29, 95% CI = 1.12-1.48, P < 0.001; additive model: OR = 1.42, 95% CI = 1.13-1.80, P = 0.003). There are no associations of IL-1β-511C/T and IL-RN polymorphisms on stroke risk were identified.

CONCLUSION

In conclusion, our results suggested that IL-1α-889C/T polymorphism is associated with stroke risk, especially in Asians. However, no associations of IL-1β-511C/T and IL-RN polymorphisms on stroke risk in overall analysis or subgroup analysis.

Common polymorphisms in the interleukin-6 gene and myocardial infarction risk: a meta-analysis

BACKGROUND

Interleukin-6 (IL-6) plays a critical role in the development and progression of cardiovascular disease. Emerging evidence suggests that two common polymorphisms (-174 G/C and -572 G/C) in the IL-6 gene might have an impact on an individual's susceptibility to myocardial infarction (MI), but individually published results are inconclusive. This meta-analysis aimed to derive a more precise estimation of the relationship between IL-6 -174 G/C and -572 G/C polymorphisms and MI risk.

METHOD

An extensive literary search for relevant studies was conducted in PubMed, Embase, Web of Science, Cochrane Library, CISCOM, CINAHL, Google Scholar, China BioMedicine (CBM), and China National Knowledge Infrastructure (CNKI) databases from their inception through August 1st, 2013. A meta-analysis was then performed using the STATA 12.0 software. The crude odds ratios (OR) with 95% confidence intervals (CI) were calculated.

RESULTS

Eleven case-control studies were included with a total of 10,252 subjects, including 5429 MI patients and 4823 healthy controls. Our meta-analysis results indicated that IL-6 -174 G/C polymorphism may increase the risk of MI (C allele vs. G allele: OR=1.07, 95% CI: 1.01-1.14, p=0.018; GC+CC vs. GG: OR=1.14, 95% CI: 1.04-1.24, p=0.003; respectively). However, our results showed no significant association between IL-6 -572 G/C polymorphism and MI risk (C allele vs. G allele: OR=0.88, 95% CI: 0.75-1.03, p=0.098; GC+CC vs. GG: OR=0.87, 95% CI: 0.70-1.07, p=0.173; respectively). No publication bias was detected in this meta-analysis.

CONCLUSION

The current meta-analysis suggests that IL-6 -174 G/C polymorphism may contribute to MI susceptibility. Thus, detection of IL-6 -174 G/C polymorphisms may be a promising biomarker for the early detection of MI. However, IL-6 -572 G/C polymorphism may not associate with the risk of MI.

Association between Interleukin-1 gene single nucleotide polymorphisms and ischemic stroke classified by TOAST criteria in the Han population of northern China

Increasing evidence suggests that IL-1β (C-511T) and IL-1α (C-889T) genes polymorphisms are associated with the susceptibility to cardiocerebral vascular disease. In this paper, we investigated the relationships between these polymorphisms and the risk of ischemic stroke (IS) classified by TOAST criteria in the north Chinese Han population. 440 cases of IS and 486 age- and gender-matched controls of Chinese Han population were enrolled. Association study showed that the TT genotype and T allele of IL-1α-889 C/T were significantly associated with IS of a large artery atherosclerosis (LAA) (TT: OR = 2.01, 95% CI = 1.34–3.0, and P < 0.001; T: OR = 1.44, 95% CI = 1.18–1.78, and P = 0.001). However, there was no significant difference in the distribution of IL-1α-889 C/T genotypes and allele frequencies between the two subgroups (small-artery occlusion (SVD) and cardioembolism (CE)) of IS and control groups. No significant association was also found between the IL-1β-511 TT genotype and T allele (TT: OR = 0.79, 95% CI = 0.56–1.11, and P = 0.175; T: OR = 0.83, 95% CI = 0.68–1.01, and P = 0.066) and IS as well as subgroups of CE and SVD. Our results implicated that IL-1α-889 C/T gene polymorphism might be associated with the susceptibility to IS, especially to IS with LAA, in a north Chinese Han population.

Associations between interleukin-1 gene polymorphisms and coronary heart disease risk: a meta-analysis

Objective

A great number of studies regarding the associations between IL-1B-511, IL-1B+3954 and IL-1RN VNTR polymorphisms within the IL-1gene cluster and coronary heart disease (CHD) have been published. However, results have been inconsistent. In this study, a meta-analysis was performed to investigate the associations.

Methods

Published literature from PubMed and Embase databases were searched for eligible publications. Pooled odds ratios (ORs) with 95% confidence intervals (CIs) were calculated using random- or fixed- effect model.

Results

Thirteen studies (3,219 cases/2,445 controls) for IL-1B-511 polymorphism, nine studies (1,828 cases/1,818 controls) for IL-1B+3954 polymorphism and twelve studies (2,987 cases/ 2,208 controls) for IL-1RN VNTR polymorphism were included in this meta analysis. The results indicated that both IL-1B-511 and IL-1B+3954 polymorphisms were not associated with CHD risk (IL-1B-511 T vs. C: OR = 0.98, 95%CI 0.87–1.09; IL-1B+3954 T vs. C: OR = 1.06, 95%CI 0.95–1.19). Similarly, there was no association between IL-1RN VNTR polymorphism and CHD risk (*2 vs. L: OR = 1.00, 95%CI 0.85–1.17).

Conclusions

This meta-analysis suggested that there were no associations between IL-1 gene cluster polymorphisms and CHD.

Genetic variation within the interleukin-1 gene cluster and ischemic stroke

BACKGROUND AND PURPOSE

Evidence is emerging that inflammation plays a key role in the pathophysiology of ischemic stroke (IS). The aim of this study was to investigate whether genetic variation in the interleukin-1α, interleukin-1β, and interleukin-1 receptor antagonist genes (IL1A, IL1B, and IL1RN) is associated with IS and/or any etiologic subtype of IS.

METHODS

Twelve tagSNPs were analyzed in the Sahlgrenska Academy Study on Ischemic Stroke (SAHLSIS), which comprises 844 patients with IS and 668 control subjects. IS subtypes were defined according to the Trial of Org 10172 in Acute Stroke Treatment criteria in SAHLSIS. The Lund Stroke Register and the Malmö Diet and Cancer study were used as a replication sample for overall IS (in total 3145 patients and 1793 control subjects).

RESULTS

The single nucleotide polymorphism rs380092 in IL1RN showed an association with overall IS in SAHLSIS (OR, 1.21; 95% CI, 1.02-1.43; P=0.03), which was replicated in the Lund Stroke Register and the Malmö Diet and Cancer study sample. An association was also detected in all samples combined (OR, 1.12; 95% CI, 1.04-1.21; P=0.03). Three single nucleotide polymorphisms in IL1RN (including rs380092) were nominally associated with the subtype of cryptogenic stroke in SAHLSIS, but the statistical significance did not remain after correction for multiple testing. Furthermore, increased plasma levels of interleukin-1 receptor antagonist were observed in the subtype of cryptogenic stroke compared with controls.

CONCLUSIONS

This comprehensive study, based on a tagSNP approach and replication, presents support for the role of IL1RN in overall IS.

Polymorphisms of interleukin-1 and interleukin-6 genes on the risk of ischemic stroke in a meta-analysis

Many epidemiological studies have investigated the associations between polymorphisms of interleukin-1 (IL1) and interleukin-6 (IL6) genes and risk of ischemic stroke (IS), but no conclusions are available because of conflicting results. The aim of this study was to assess the relationships by meta-analysis. The databases of Pubmed, Embase and Wangfang, updated to August 1st, 2011, were retrieved. Odds ratio (OR) and corresponding 95% confidence interval (95% CI) as effect size were calculated by a fixed- or random-effect model. In total, three case-control studies for IL1α-889C/T, eight studies for IL1β-511C/T, eight studies for IL1-Ra and seven studies for IL6-147G/C were included in this meta-analysis. Combined analysis indicated that IL1β-511C/T polymorphism was not overall associated with risk of IS [OR (95% CI)=1.22 (0.85-1.87) for TT vs. CC]. However, when subgroup analyses for countries were conducted, the results indicated that T allele was associated with increased risk of IS for Polish and associated with a trend of increased risk of IS for Chinese although it did not reach statistical significance [TT vs. CC: OR (95% CI)=1.97 (1.22-3.17) for Polish and 1.40 (0.99-1.99) for Chinese]. In addition, overall and subgroup analyses indicated that IL1α-889C/T, IL1-Ra and IL6-147G/C polymorphisms were also not associated with risk of IS [OR (95% CI)=1.21 (0.86-1.70) for TT vs. CC of IL1α-889C/T, 1.22 (0.85-1.75) for RN2/RN2 vs. RN1/RN1 for IL1-Ra and 1.09 (0.84-1.40) for G carriers vs. C carriers for IL6-147G/C]. This study inferred that IL1β-511C/T polymorphism might be moderately associated with increased risk of IS, but no sufficient evidence was available to support any associations between IL1-Ra and IL6-147G/C polymorphisms and IS. We could not draw a conclusion between IL1α-889C/T polymorphism and risk of IS based on the limited data, and further large sample-sized studies were required.

Genetic variation of the interleukin-1 family and nongenetic factors determining the interleukin-1 receptor antagonist phenotypes

The natural anti-inflammatory protein interleukin-1 receptor antagonist (IL-1Ra) inhibits the activity of IL-1 and is associated with vascular injury and metabolic disorders. We analyzed genetic and nongenetic determinants of the IL-1Ra phenotype. Fifteen haplotype-tagging single nucleotide polymorphisms (SNPs) in the IL-1α (IL1A), IL-1β (IL1B), and IL-1 receptor antagonist (IL-1RN) genes were determined in the Health 2000 survey (n = 6771) and European myocardial infarction (MI) survivors (n = 972). Three SNPs were genotyped in the FINRISK97 (FR97) study (n = 7222). We found 3 IL1RN variants that were associated with the IL-1Ra phenotype in the study populations and remained significant after Bonferroni correction with increasing significance in meta-analysis (P values for rs3213448,rs315952, rs315949, respectively: 5.5 x 10(-11), 1.5 x 10(-11), and 4.0 x 10(-14)). Minor allele of the rare IL1B variant rs1143642 was associated with decreased IL-1Ra levels in the Health 2000 and FR97 populations, and the association strengthened in the meta-analysis (P = 9.4 x 10(-7)). The proportion of variance explained by the IL1RN variant was larger in MI survivors (5.0%) than in the unselected population (0.5%). Body mass index was the strongest nongenetic predictor of the IL-1Ra phenotype, explaining 11.8% of the variance in Health 2000, 18.1% in FR97, and 25% in MI survivors. In conclusion, 3 IL1RN SNPs and 1 IL1B variant were determining IL-1Ra phenotype independently of body mass index and other metabolic phenotypes. The proportion of phenotypic variation in IL-1Ra explained by the genetic variants was, however, modest compared with the proportion explained by the body mass index.

Implications of genetic polymorphisms in inflammation-induced atherosclerosis

Inflammation is the mainstay of atherosclerosis and is an important governing factor at all stages of the disease process from lesion formation to plaque build-up and final end-stage rupture and thrombosis. An overview of the numerous clinico-epidemiological studies on the association between inflammatory gene polymorphisms and Cardiovascular disease (CVD) and its co-morbidities have shown that the risk associated with any single genotype is modest while the haplotypes, especially those defined on the basis of tag-SNP approach, have better coverage of the gene and show moderately higher impact on disease risk. Nevertheless, even these associations have been inconsistent with low cross-race repeatability. This has been attributed to many plausible causes such as clinical heterogeneity, sample selection criteria, variable genetic landscapes across different ethnic groups, confounding effect of co-morbidities etc. On the other hand, unbiased studies such as the family-based linkage and case-control based associations that have taken into account, thousands of genotypic markers spanning the whole genome, have had the ability to identify novel genetic loci for coronary artery disease. These studies have shown that many inflammatory genes are involved in the regulation of specific biomarkers of inflammation that collectively contribute to the disease-associated risk. In addition, there appears to be considerable cross talk between the different biochemical and metabolic processes. Therefore, consideration of all these factors can build towards an 'atherosclerotic bionetwork' that can refine our quest for developing a robust risk stratification tool for cardiovascular disease.

The role of IL-1 in the pathogenesis of heart disease

Interleukin (IL)-1 consists of two distinct ligands, IL-1alpha and IL-1beta, with indistinguishable biological activities that signal through the IL-1 type I receptor (IL-1RI). A naturally occurring IL-1 receptor antagonist (IL-1Ra) binds to IL-1RI without initiating signal transduction and prevents IL-1 signaling, competitively inhibiting IL-1-mediated responses. Emerging evidence suggests that the balance between IL-1 agonists and antagonists plays an essential role in a variety of cardiovascular conditions. IL-1 may play a role in atherothrombotic disease by promoting the formation of atheromatous lesions, enhancing vascular inflammation, and triggering plaque destabilization. Following myocardial infarction, IL-1 critically regulates the inflammatory response and is involved in the development of adverse remodeling by enhancing expression of matrix metalloproteinases. IL-1 signaling may also be an essential mediator in the pathogenesis of heart failure by suppressing cardiac contractility, promoting myocardial hypertrophy, and inducing cardiomyocyte apoptosis. The present review summarizes current available data showing the significant role of IL-1 signaling in heart disease and raising the possibility that IL-1 inhibitors (such as anakinra, a nonglycosylated recombinant human IL-1Ra) may be clinically useful agents in patients with certain cardiovascular conditions.

Cytokines and myelination in the central nervous system

Myelin abnormalities that reflect damage to developing and mature brains are often found in neurological diseases with evidence of inflammatory infiltration and microglial activation. Many cytokines are virtually undetectable in the uninflamed central nervous system (CNS), so that their rapid induction and sustained elevation in immune and glial cells contributes to dysregulation of the inflammatory response and neural cell homeostasis. This results in aberrant neural cell development, cytotoxicity, and loss of the primary myelin-producing cells of the CNS, the oligodendrocytes. This article provides an overview of cytokine and chemokine activity in the CNS with relevance to clinical conditions of neonatal and adult demyelinating disease, brain trauma, and mental disorders with observed white matter defects. Experimental models that mimic human disease have been developed in order to study pathogenic and therapeutic mechanisms, but have shown mixed success in clinical application. However, genetically altered animals, and models of CNS inflammation and demyelination, have offered great insight into the complexities of neuroimmune interactions that impact oligodendrocyte function. The intracellular signaling pathways of selected cytokines have also been highlighted to illustrate current knowledge of receptor-mediated events. By learning to interpret the actions of cytokines and by improving methods to target appropriate predictors of disease risk selectively, a more comprehensive understanding of altered immunoregulation will aid in the development of advanced treatment options for patients with inflammatory white matter disorders.