Interleukin-6 gene polymorphism is an age-dependent risk factor for myocardial infarction in men

Several studies show that inflammatory components may contribute to atherosclerosis and increase the risk for myocardial infarction (MI). Interleukin-6 (IL-6) is a key pro-inflammatory and immune-modulatory cytokine of relevance for cardiovascular diseases. In this case-control study, 200 patients with MI and 257 healthy controls were genotyped for the polymorphism present in -174 promoter region of the IL-6 gene. Plasma concentrations of IL-6 and C-reactive protein (CRP) in a group of patients and controls were measured. The -174 C allele was associated with an increased risk of developing MI (OR = 2.886, c.i. = 1.801-4.624, P = 0.0001) in older patients, while no association was found in younger ones. The IL-6 plasma levels were higher in patients with MI carrying the CC genotype than in GG patients (CC carriers, IL-6 = 2.97 pg mL(-1) vs. GG carriers = 1.81 pg mL(-1), P = 0.016). A positive correlation of IL-6 levels with those of CRP in serum from patients with MI was also found. Data from this study suggest that the C allele of the promoter polymorphism in the IL-6 gene is a risk factor for MI in the elderly, and the production of the IL-6 is differentially affected by different genotypes of the IL-6 -174 promoter polymorphism.     

Interleukin-6 promoter polymorphism and late-onset Alzheimer's disease in the Finnish population

Recently, the involvement of the inflammatory response in Alzheimer's disease (AD) has received considerable attention. The gene encoding for interleukin-6 (IL-6) is interesting since IL-6 has been reported not only to be involved in immune functions but also in AD. We investigated whether the IL-6-174 G/C polymorphism is associated with late onset AD (LOAD) in the Finnish subjects. The G allele was over-represented in ApoE4-LOAD patients but remained unimportant in all and in the ApoE E4 carriers. Interestingly, the G allele frequency was lower in our population in both AD patients and in controls compared to Southern European populations.     

Polymorphisms in genes coding for mediators in the interleukin cascade and their effect on susceptibility to sarcoidosis in the Slovenian population

Sarcoidosis is a chronic inflammatory disease characterised by granulomatous inflammation in various organs. As genetic factors have been implicated in its aetiology, in our study we investigated whether the promotor polymorphisms in three genes coding for inflammatory mediators interleukin-6 (IL-6), interleukin-12 (IL-12), and interleukin-18 (IL-18) could be associated with susceptibility to sarcoidosis. The study sample consisted of 104 patients with sarcoidosis and 100 healthy control subjects. Following DNA isolation from peripheral blood the IL-6/-174G>C single nucleotide polymorphism (SNP), the IL-12B/4 bp insertion polymorphism, and the IL-18/-137G>C SNP were characterised by polymerase chain reaction. Our results showed an increased frequency of IL-6/-174C allele (p<0.01, OR=2.05, 95% CI=1.32-3.16), and also an increased genotype frequency of IL-6/-174 CC and CG carriers (p<0.01, OR=2.78, 95% CI=1.49-5.19) among sarcoidosis patients in comparison with healthy controls. Allele and genotype frequencies did not differ significantly between cases and controls for either the IL-12B/4 bp insertion polymorphism or for the IL-18/-137G>C polymorphism. In conclusion, we demonstrated that the -174G>C promotor polymorphism in the IL-6 gene may be a risk factor for sarcoidosis.     

A common functional variant in the interleukin-6 gene is associated with increased body mass index in subjects with type 2 diabetes mellitus

Circulating levels of interleukin-6 (IL-6) are raised in insulin resistant states such as obesity, impaired glucose tolerance (IGT), and type 2 diabetes mellitus (T2DM). Growing evidence suggests that IL-6 is not only produced by fat cells but is also capable of inducing insulin resistance in these cells. The expected result of this in vivo, would be to increase adipose mass and subsequently body mass index (BMI). The IL-6 -174G > C common functional gene variant has consistently been associated with increased plasma IL-6, insulin resistance, and increased cardiovascular risk. We looked at the association between genotype and BMI in 571 Caucasian subjects with T2DM. There was a significant linear association between genotype and BMI: Median (interquartile range) GG 28.8 kg/m2 (26.0-31.6) vs GC; 29.4 kg/m2 (26.3-32.5) vs CC; 30.4 kg/m2 (26.1-33.0), p=0.05. When the group was divided by the median BMI (29.1 kg/m2), 62% of -174CC subjects were in the higher group compared to 38% in the lower group (p=0.008). By contrast, in 2,652 non-diabetic Caucasian men with a median BMI of 26.1 kg/m2, there was no difference in genotype distribution (p=0.288). The frequency of the -174C allele was lower in type 2 diabetes compared to the non-diabetic men (-174C allele frequency: 0.35[0.33-0.38] vs 0.43[0.42-0.45], p <0.00001; -174CC homozygotes: 12.3 vs 18.3%, respectively). The -174C allele is associated with higher BMI in type 2 diabetes, but not amongst healthy subjects. The increased cardiovascular risk associated with the -174C allele may account for the lower frequency of this allele in those with type 2 diabetes.     

C-reactive protein levels and common polymorphisms of the interleukin-1 gene cluster and interleukin-6 gene in patients with coronary heart disease.

C-reactive protein (CRP) is an inflammatory marker associated with increased cardiovascular risk. Production of CRP is regulated by interleukin (IL)-1beta, IL-1 receptor antagonist and IL-6. In 160 patients with coronary heart disease (CHD) confirmed by angiography, we examined the relationship between CRP level and five polymorphisms in genes coding for these cytokines: IL-1B(-511), IL-1B(+3954), a variable number tandem repeat (VNTR) polymorphism in intron 2 of IL-1RN [IL-1RN(VNTR)], IL-6(-174) and IL-6(-572). CRP values were logarithmically normalized (log-CRP) for statistical calculations. In univariate analysis, carrier status for the IL-1B(+3954)T allele and IL-1RN(VNTR) allele 2 [IL-1RN(VNTR)*2] correlated with higher (P < 0.01) and lower (P < 0.05) log-CRP values, respectively. Among the potential confounding factors analysed, smoking, body mass index, total cholesterol (P < 0.05 for all) and diabetes (P = 0.056) were positively correlated with CRP level. After adjustment for non-genetic covariates, CRP levels remained significantly (P < 0.01) higher in carriers of IL-1B(+3954)T than in non-carriers: mean log-CRP (with 95% confidence interval) was 0.443 (0.311-0.574) for CT or TT genotypes compared with 0.240 (0.107-0.373) for the CC genotype, which corresponded to back-transformed CRP levels of 2.77 and 1.74 mg l(-1), respectively. Adjusted association was also significant for IL-1RN(VNTR)*2 (P < 0.01), with lower CRP levels in the presence of allele 2: the mean log-CRP value was 0.252 (0.115-0.388) for carriers and 0.421 (0.290-0.552) for non-carriers (CRP 1.79 and 2.64 mg l(-1), respectively). When alleles of both polymorphisms were entered into the model simultaneously, the association remained significant for IL-1B(+3954)T (P < 0.05), but not for IL-1RN(VNTR)*2. We conclude that IL-1B(+3954)T is associated with higher CRP levels in patients with CHD, and we found that this association was significant after adjustment for major risk factors. Our data also suggest a possible relationship of IL-1RN(VNTR)*2 with lower CRP levels in the same patients.     

The concomitant presence of polymorphic alleles of interleukin-1beta, interleukin-6 and apolipoprotein E is associated with an increased risk of myocardial infarction in elderly men. Results from a pilot study

Genetic background of inflammatory or anti-inflammatory molecules may be helpful in identifying subjects with increased or decrease risk of developing cardiovascular disease. Bi-allele polymorphism (C > T) in the promoter region (-511) of the interleukin-1beta (IL-1beta) gene and the bi-allele polymorphism (G > C) in the promoter region (-174) of interleukin-6 (IL-6) gene were determined in elderly men patients with myocardial infarction (MI) and healthy controls. Each subject was also genotyped for the triallelic polymorphism of the apolipoprotein E epsilon gene. The IL-6C and APOE epsilon4 alleles were independently associated with a mild or moderate increased risk of MI, whilst the allele C of the IL-1beta was not independently linked to MI risk. However, the simultaneous presence of the allele C of IL-1beta, the allele C of IL-6 and epsilon4 allele of APOE was strongly associated with the disease. Data from this cross-sectional study suggest that the functional interaction of these three genes affects pathogenetic mechanisms of MI and an impaired regulation of immune responses plays a pivotal role in the disease. Furthermore, genetic background of inflammatory genes may influence longevity of human species by affecting inflammatory responses associated to cardiovascular diseases. The administration of anti-inflammatory compounds to middle age healthy subjects with increased genetic susceptibility of developing MI might decrease the incidence and prevalence of cardiovascular events in aging.     

IL-1B and IL-6 gene polymorphisms encode significant risk for the development of recurrent aphthous stomatitis (RAS)

Recurrent aphthous stomatitis (RAS) is an, ulcerative condition of the mouth, with a polygenic mode of inheritance in which cytokines are thought to play an important role. Ninety-one RAS patients and 91 controls were genotyped for known IL-1A, IL-1B, IL-1RN and IL-6 gene polymorphisms. Inheritance of the G allele of the IL-1B -511 polymorphism was strongly associated with RAS (OR = 2.5, P < 0.00002), with increased numbers of G/G homozygotes (OR = 4.5, P < 0.0005). The G allele of IL-6 -174 also occurred more frequently in RAS (OR = 2.6, P < 0.0001) with greatest risk associated with G/G homozygosity (OR = 3.4, P < 0.0001). IL-1RN VNTR 1/1 homozygotes also occurred more frequently in RAS (OR = 2.0, P < 0.02). Inheritance of the G/G genotype of both IL-1B and IL-6 was a particularly strong predictor for RAS (OR = 8.5).     

白细胞介素-6基因多态性与再生障碍性贫血的相关研究

目的探讨白细胞介素-6（IL-6）基因启动子区域-174G/C基因多态性与中国北方汉族人再生障碍性贫血（AA）的相关性。方法应用顺序特异性引物和聚合酶链反应（PCR-SSP）技术,检测了36例AA患者（再障组）和40例健康献血者（对照组）中IL-6基因位点的多态性变化。结果结果表明IL-6基因-174G/C多态性位点基因型频率和等位基因频率在两组人群中的分布差异有统计学意义（χ2=6.31,P〈0.05）,G等位基因携带者患AA的风险是C等位基因的3.74倍（OR=3.7405）。两组之间比较差异有显著性意义,提示该等位基因频率增高与AA相关。结论IL-6基因-174G/C多态性与AA的发病具有相关性,其中G等位基因可能是我国北方汉族人AA发病的遗传易感基因,携带G等位基因的个体可能通过促进IL-6的高度表达进而增加AA的发病风险。     

阿尔茨海默病患者环氧化酶-2基因启动子区多态性分析

目的检测环氧化酶-2(COX-2)基因的1195和765两个多态位点,探讨其与阿尔茨海默病(AD)的可能相关性。方法采用Qiagen DNA提取试剂盒提取外周血白细胞DNA,根据位点基因序列设计引物,采用PCR-限制性片段长度多态分析(PCR-RFLP)分别对90例AD患者(AD组)和110例正常人(对照组)进行基因分型,PCR扩增出各样本的目的片断,对扩增产物进行酶切,酶切产物经2%琼脂糖凝胶电泳,EB染色,凝胶成像系统判定结果。结果AD组共检出3种COX-2-1195基因型,GG基因型频率为21.0%,GA基因型频率为50.0%,AA基因型频率为29.0%,G、A等位基因频率分别为46.1%和53.9%,与对照组比较,差异均无统计学意义;GG基因型频率为77.8%,GC基因型频率为20.0%,CC基因型频率为2.2%,G、C等位基因频率分别为87.8%和12.2%,与对照组比较,AD组中CC基因型频率、C等位基因频率差异均有统计学意义。COX-2蛋白水平在AD组和对照组分别为(124.95±8.73)IU/L、(51.81±7.33)IU/L,差异有统计学意义(P<0.05)。结论①COX-2基因启动子区-1195G/A多态性可能与中国南方人群AD的发生无关;②COX-2基因～765G/C与AD的发生有关,-765G/C多态性可能是AD发生的一风险因素;③AD患者血浆中COX-2蛋白水平升高,可能是由于COX-2基因-765G/C多态性引起。     

Genotypes and haplotypes in the IL-1 gene cluster: analysis of two genetically and diagnostically distinct groups of Alzheimer patients

Increased risk of Alzheimer's disease (AD) has been associated with polymorphisms in the IL-1 gene cluster, and in particular with the IL-1alpha-889 T/T genotype. However, this association is still unclear, and needs further investigation. In order to clarify the role of these polymorphisms in the complex pathogenesis of AD we examined genotype and haplotype frequencies of the two C-to-T SNPs at position -889 and -551 in the IL-1alpha and IL-1beta genes, respectively, and of the 86 bp VNTR intron-2 polymorphisms in the IL-1Ra gene. The analysis was performed in two genetically and diagnostically distinct groups of sporadic AD from Italy and the USA. In the Italian group a significant association between the IL-1alpha-889 T/T genotype and AD (OR=3.022, 95% CI: 1.001-9.119) was found, whereas no difference was found in the group from the USA. Results were also compared with previously published studies that analyzed the same IL-1 polymorphisms in AD. In both groups, the analysis of the estimated haplotypes shows that AD patients and controls who carry the IL-1beta-511 C allele, were also more frequently carriers of the IL-1Ra 1 allele (haplotypes -C-1). The total frequency of the two -C-1 haplotypes (C-C-1 plus T-C-1) was about one half of the total frequency of the eight estimated haplotypes. This was confirmed by significant linkage disequilibrium between these two loci in both the Italian and USA groups. In the Italian group a weak association of the T-C-2 haplotype with the disease (OR=1.648, 95% CI: 1.519-1.788) was also found, whereas in the USA group no difference was found. Although ours and other published data on different samples of Caucasian and non-Caucasian AD show a great heterogeneity in the frequencies of the IL-1alpha-889, the IL-1beta-511 and the IL-1Ra VNTR gene polymorphisms, we confirm the role of the IL-1alpha-889 T/T genotype as a risk factor for sporadic AD, and show the presence of an allelic association between IL-1beta C and IL-1Ra 1 alleles in both the Italian and the USA groups, confirmed by the presence of significant levels of linkage disequilibrium between these two loci.     

Tumor necrosis factor-α -308 G>A and interleukin-6 -174 G>C promoter polymorphisms and pemphigus

The objective of this study was to analyze the possible involvement of the tumor necrosis factor (TNF)-α -308 G>A and interleukin-6 (IL-6) -174 G>C polymorphisms in the susceptibility and/or disease profile of pemphigus in Egyptian patients. Detection of TNF-α -308 G>A by amplification refractory mutation system and IL-6 -174 G>C by restriction fragment length polymorphism was performed for 70 patients and 203 controls. No significant differences were observed in the distribution of TNF-α -308 in pemphigus patients and controls. However, GA+AA genotypes were more frequent in pemphigus vulgaris (PV) patients only versus controls (p(c) = 0.046). The frequency of the C allele and CC/GC genotypes of IL-6 -174 was significantly higher in pemphigus patients and those with the 2 major clinical forms (PV and pemphigus foliaceus [PF]) compared with controls (p < 0.05). Comparison of the distribution of TNF-α -308 and IL-6 -174 variants in relation to clinical type of pemphigus (PV versus PF), activity score, recurrence, and demographic data of patients revealed no significant associations. The IL-6 -174 CC genotype represents a marker of increased susceptibility to pemphigus in Egyptian patients and GG genotype can be considered a low-risk genotype; TNF-α -308 A-containing genotypes contribute to the susceptibility to PV only.     

白细胞介素-6基因多态性与卵巢癌的相关性研究

目的探讨白细胞介素-6(IL-6)基因启动子区域-174G/C基因多态性与中国北方汉族人卵巢癌的关系。方法采用序列特异性引物聚合酶链反应(PCR-SSP)技术,检测33例卵巢癌患者组和90例正常对照组IL-6基因多态性。结果IL-6基因-174G/C多态性位点基因型频率和等位基因频率在两组人群中的分布差异有统计学意义(x2=6.31,P<0.05),G等位基因携带者患卵巢癌的风险是C等位基因的3.74倍(OR=3.7405)。结论IL-6基因-174G/C多态性与卵巢癌的发病具有相关性,其中G等位基因可能是我国北方汉族人卵巢癌发病的遗传易感基因,携带G等位基因的个体可能通过促进IL-6的高度表达进而增加卵巢癌的发病风险。     

INTERLEUKIN-6 PROMOTER POLYMORPHISM AND LATE-ONSET ALZHEIMER's DISEASE IN THE FINNISH POPULATION

Recently, the involvement of the inflammatory response in Alzheimer's disease (AD) has received considerable attention. The gene encoding for interleukin-6 (IL-6) is interesting since IL-6 has been reported not only to be involved in immune functions but also in AD. We investigated whether the IL-6-174 G/C polymorphism is associated with late onset AD (LOAD) in the Finnish subjects. The G allele was over-represented in ApoE4-LOAD patients but remained unimportant in all and in the ApoE E4 carriers. Interestingly, the G allele frequency was lower in our population in both AD patients and in controls compared to Southern European populations.     

Sphingosine-1-phosphate acting via the S1P₁ receptor is a downstream signaling pathway in ceramide-induced hyperalgesia

Interleukin-6 (IL-6), identified as a pleiotropic inflammatory cytokine, plays important roles in the acute inflammatory response and in the modulation of the neuroimmune response. To date, large amounts of epidemiological studies have been performed to investigate the association between the IL-6 −174G/C polymorphism and Alzheimer's disease (AD) risk. Inconclusive results, however, have been reported. We aimed to assess the effect of the IL-6 −174G/C polymorphism on AD susceptibility with the use of a meta-analysis. 14 studies involving 3769 cases of AD and 9431 control subjects were identified by a search of Pubmed, Embase and ISI Web of Science databases. Crude odds ratios (ORs) with 95% confidence intervals (CIs) for the IL-6 −174G/C polymorphism and AD risk were computed using fixed- or random-effects model when appropriate. Obvious heterogeneity among studies was detected, and a borderline statistically significant association was observed between the IL-6 −174G/C polymorphism and AD risk in Caucasians (GG vs. CC: OR = 1.35, 95%CI, 1.06-1.72; GG/GC vs. CC: OR = 1.27, 95%CI, 1.05-1.53, respectively). After exclusion of one study, the heterogeneity disappeared and no significant association was observed between the polymorphism and AD risk. These findings indicate that the IL-6 −174G/C polymorphism may not be an independent risk factor for the development of AD.     

Association of G-174C polymorphism of the interleukin-6 gene promoter with Graves' ophthalmopathy

Interleukin-6 (IL-6) may play an important role in the pathogenesis of Graves' ophthalmopathy (GO). The aim of this study was to analyze the association of IL-6 gene promoter polymorphism, at position - 174 (G --> C, termed as G-174C), which may affect IL-6 production, with the development of GO. The G-174C polymorphism was determined in 279 Polish-Caucasian patients with Graves' disease (GD), of which 108 had clinically evident ophthalmopathy (NOSPECS class III or higher) and 186 healthy Polish adults. In patients with GD, the frequencies of the C allele (45 vs 42%; P = 0.35) and C/C genotype (20 vs 15%; P = 0.13) were not significantly different compared to controls. Subdividing patients with GD for the presence of eye disease revealed that the C allele (44 vs 45%; P = 0.76) and C/C genotype (20 vs 20%; P = 0.92) were equally distributed in patients with or without ophthalmopathy. There was also no association between the G-174C polymorphism and the severity of eye changes. Finally, IL-6 genotypes were not associated with laboratory findings (thyroid volume, serum IL-6 and thyroid autoantibodies levels) in patients with GD at diagnosis. Our results suggest that G-174C polymorphism of the IL-6 gene does not contribute to the development and severity of GO.     

Association of G-174C Polymorphism of the Interleukin-6 Gene Promoter with Graves' Ophthalmopathy

Interleukin-6 (IL-6) may play an important role in the pathogenesis of Graves' ophthalmopathy (GO). The aim of this study was to analyze the association of IL-6 gene promoter polymorphism, at position -174 (G→C, termed as G-174C), which may affect IL-6 production, with the development of GO. The G-174C polymorphism was determined in 279 Polish-Caucasian patients with Graves' disease (GD), of which 108 had clinically evident ophthalmopathy (NOSPECS class III or higher) and 186 healthy Polish adults. In patients with GD, the frequencies of the C allele (45 vs 42%; P=0.35) and C/C genotype (20 vs 15%; P=0.13) were not significantly different compared to controls. Subdividing patients with GD for the presence of eye disease revealed that the C allele (44 vs 45%; P=0.76) and C/C genotype (20 vs 20%; P=0.92) were equally distributed in patients with or without ophthalmopathy. There was also no association between the G-174C polymorphism and the severity of eye changes. Finally, IL-6 genotypes were not associated with laboratory findings (thyroid volume, serum IL-6 and thyroid autoantibodies levels) in patients with GD at diagnosis. Our results suggest that G-174C polymorphism of the IL-6 gene does not contribute to the development and severity of GO.     

A polymorphism in the promoter region of the gene for interleukin-6 is associated with susceptibility to type 1 diabetes mellitus.

Type 1 diabetes mellitus is an autoimmune disease characterized by the destruction of the insulin-producing islet beta cells. It is likely that several genetic and environmental factors contribute to this process. There is increasing evidence showing that polymorphisms in cytokine genes may play an important role in modifying the immune response. Interleukin-6 (IL-6) is a cytokine that has been implicated in a number of immune-mediated diseases. Further, there is a polymorphism at position -174 (G(-174)C) of the promoter region of the IL-6 gene that may alter the expression of the gene. In this study, the G(-174)C polymorphism was investigated in 257 Caucasoid patients with type 1 diabetes, 53 two-parent-proband trios, and 120 normal, healthy controls. DNA was amplified using amplimers that flank the G(-174)C site, and the products were digested with the restriction endonuclease NlaIII to detect the G or the C allele. The homozygous G,G(-174) genotype was increased in the patients compared with the normal controls (50.6% vs. 33.3%, p < 0.002), with a decrease in the C,C genotype in the patients compared with the controls (12.5% vs. 24.2%, respectively, p < 0.004). In the 53 trios studied, the G allele was transmitted in 29 of 53 informative meioses. There was no association with age at onset of diabetes or the presence of diabetic complications. In conclusion, these results suggest that the IL-6 gene may contribute to the genetic susceptibility to type 1 diabetes.     

MTHFR (677 and 1298) and IL-6-174 G/C genes in pathogenesis of Alzheimer's and vascular dementia and their epistatic interaction

Genetic risk factors play an important role in the pathogenesis of Alzheimer disease (AD) and vascular dementia (VaD). In this case-control study, we examined C677T and A1298C (rs1801133 and rs1801131) polymorphism in the methylenetetrahydrofolate reductase (MTHFR) genes and their correlation with plasma levels of homocysteine (Hcy) in AD and VaD cases and evaluated the gene-gene interaction (epistasis) with IL-6-174 G/C (rs1800795). CC genotype was associated with elevated levels of plasma homocysteine (p = 0.004) as compared with genotype AA of rs1801131. In AD, we observed a significant (p = 0.04) association with C alleles of rs1801131. Regression analysis revealed that the presence of both rs1801133 T and rs1800795 C alleles increased the odds of developing AD by 2.5 and VaD by 3.7-fold. While rs1800795 (CC or GC) genotypes alone increased the odds of developing VaD by 2.2-fold, the presence of CC genotype of rs1801131 nullified this effect. The findings support the hypothesis that multiple genes are involved to alter the odds of developing AD and VaD.