Interleukin-6 Single Nucleotide Polymorphisms Research Articles

Interleukin‐6 Receptor Gene Polymorphism Modulates Interleukin‐6 Levels and the Metabolic Syndrome: GBCS‐CVD

Interleukin-6 (IL-6) is a key pleiotropic cytokine that modulates the inflammatory response. Single-nucleotide polymorphisms (SNPs) within associated genes may contribute to the metabolic syndrome (MES). We examined the role of the IL-6 (rs1524107-C/T) and IL-6 receptor (IL-6R, rs8192284-A/C, Asp358Ala) SNPs in modulating IL-6 levels and the syndrome. A total of 1,979 older Chinese subjects aged 50-92 years from Guangzhou Biobank Cohort Study (GBCS) were recruited. SNPs were detected using Taqman SNP genotyping kits. IL-6 was measured using enzyme-linked immunosorbent assay. The genotype frequencies were 4.9, 33.9, and 61.3% for the IL-6 CC, CT, and TT, and 12.0, 44.9, and 43.1% for the IL-6R CC, AC, and AA, respectively. Both SNPs were in Hardy-Weinberg equilibrium. The IL-6 SNP was not associated with IL-6 levels or the MES, but was dose-dependently associated with fibrinogen levels, P = 0.049. IL-6 levels significantly decreased with increasing proportions of the IL-6R A-allele 9.8 ± 4.9, 9.3 ± 4.8, and 8.4 ± 4.3, respectively, P = 0.001. Conversely, the A-allele was associated with elevated triglyceride, P = 0.009, C-reactive protein, P = 0.047, and potentially with fasting glucose levels, P = 0.077. There was an increasing prevalence of the MES in those carrying the IL-6R CC, AC, and AA genotypes at 18.1, 21.5, 25.2%, respectively, P = 0.010. The SNP was a significant independent predictor of the MES after adjusting for general obesity, age, gender and lifestyle, and socioeconomic parameters, P = 0.023. These data, which are in accord with studies from white populations suggest the IL-6R SNP may play a role in the pathogenesis of the MES possibly through modulating IL-6 levels.

Polymorphisms in IL13 pathway genes in asthma and chronic obstructive pulmonary disease

Asthma and chronic obstructive pulmonary disease (COPD) are chronic respiratory diseases involving an interaction between genetic and environmental factors. Interleukin-13 (IL13) has been suggested to have a role in both asthma and COPD. We investigated whether single nucleotide polymorphisms (SNPs) in the IL13 pathway may contribute to the susceptibility and severity of asthma and COPD in adults. Twelve SNPs in IL13 pathway genes -IL4, IL13, IL4RA, IL13RA1, IL13RA2 and STAT6- were genotyped in subjects with asthma (n = 299) and in subjects with COPD or healthy smokers (n = 992). Genetic association was evaluated using genotype and allele models for asthma severity, atopy phenotypes and COPD susceptibility. Linear regression was used to determine the effects of polymorphism on baseline lung function (FEV(1), FEV(1)/FVC). In asthmatics, three IL13 SNPs - rs1881457(-1512), rs1800925(-1111) and rs20541(R130Q) - were associated with atopy risk. One SNP in IL4RA1 [rs1805010(I75V)] was associated with asthma severity, and several IL13 SNPs showed borderline significance. IL13 SNPs rs1881457(-1512) and rs1800925(-1111) were associated with better FEV(1) and FEV(1)/FVC in asthmatics. IL13 SNPs rs2066960(intron 1), rs20541(R130Q) and rs1295685(exon 4) were associated with COPD risk and lower baseline lung function in the recessive model. In females, but not in males, rs2250747 of the IL13RA1 gene was associated with COPD and lower FEV(1). These data suggest that IL13 SNPs (promoter and coding region) and, to a lesser extent, IL4RA SNPs may contribute to atopy and asthma. We also provide tentative evidence that IL13 SNPs in the coding region may be of significance in COPD susceptibility.

Cox-2 and IL-10 Polymorphisms and Association with Squamous Cell Carcinoma of The Head and Neck in a Korean Sample

Cyclooxygenase-2 (COX-2) is involved in inflammation and carcinogenesis. Interleukin-10 (IL-10) is also regarded as anti-inflammatory factors with the multi-functional ability to positively and negatively influence functional immunity and tumor development. Genetic polymorphisms of COX-2 and IL-10 might contribute to the development of squamous cell carcinoma of the head and neck (SCCHN). The purpose of this study was to evaluate the association of COX-2 and IL-10 single nucleotide polymorphisms (SNPs) with the risk of SCCHN in a Korean sample. We analyzed the COX-2 SNPs, -1329A>G, +1266C>T, and +6365T>C, and the IL-10 SNPs, -1082A>G, +920T>G, and +3917T>C, in 290 Korean SCCHN patients and 358 healthy controls. There was no significant association between the risk of SCCHN and the three COX-2 or three IL-10 SNPs. We analyzed three haplotypes (ht1, ht2, ht3) for COX-2 and found that COX-2 ht3+/+ was associated with a decreased risk of SCCHN in a Korean sample, compared with the COX-2 ht3 -/- genotype (P=0.03). Two haplotypes (ht1, ht2) of IL-10 were analyzed and there was no statistical significance in the distribution of haplotypes. Based on these results, the COX-2 haplotype ht3 can be used as a molecular biomarker to predict low risk groups of SCCHN in a Korean sample.

Association of Polymorphisms in Interleukin‐10 Gene Promoter with Autoantibody Production in Patients with Rheumatoid Arthritis

Interleukin-10 (IL-10) is a major anti-inflammatory cytokine that plays a crucial role in the regulation of the immune system. Allelic polymorphisms in the IL-10 gene promoter may contribute to the regulation of autoantibody production. To examine the association between both individuals IL-10 single nucleotide polymorphisms and the production of autoantibodies and the radiographic progression of rheumatoid arthritis (RA), a total of 144 RA patients were recruited into the study. We found significant differences in genotype distribution of the -1082G/A polymorphism between IgG, IgA, and IgM rheumatoid factor(RF)-positive/negative RA patients. We also found significant differences in allelic frequencies of the -3575T/A, -819C/T, and -592A/C polymorphisms between anticyclic citrullinated peptide (anti-CCP)-positive/negative RA patients. The haplotype TGAATA was found to be less frequent within anti-CCP-positive RA patients. Results obtained in this study provide evidence of an association between polymorphisms in IL-10 gene promoter and the production of autoantibodies in RA patients.

Cytokine and cytokine receptor single-nucleotide polymorphisms predict risk for non-small cell lung cancer among women.

Studies on the relationships between inflammatory pathway genes and lung cancer risk have not included African-Americans and have only included a handful of genes. In a population-based case-control study on 198 African-American and 744 Caucasian women, we examined the association between 70 cytokine and cytokine receptor single-nucleotide polymorphisms (SNPs) and risk of non-small cell lung cancer (NSCLC). Unconditional logistic regression was used to estimate odds ratios and 95% confidence intervals in a dominant model adjusting for major risk factors for lung cancer. Separate analyses were conducted by race and by smoking history and history of chronic obstructive pulmonary disease among Caucasians. Random forest analysis was conducted by race. On logistic regression analysis, IL6 (interleukin 6), IL7R, IL15, TNF (tumor necrosis factor), and IL10 SNP were associated with risk of non-small cell lung cancer among African-Americans; IL7R and IL10 SNPs were also associated with risk of lung cancer among Caucasians. Although random forest analysis showed IL7R and IL10 SNPs as being associated with risk for lung cancer among African-Americans, it also identified TNFRSF10A SNP as an important predictor. On random forest analysis, an IL1A SNP was identified as an important predictor of lung cancer among Caucasian women. Inflammatory SNPs differentially predicted risk for NSCLC according to race, as well as based on smoking history and history of chronic obstructive pulmonary disease among Caucasian women. Pathway analysis results are presented. Inflammatory pathway genotypes may serve to define a high risk group; further exploration of these genes in minority populations is warranted.

Associations of IL6 polymorphisms with lung function decline and COPD.

Interleukin-6 (IL6) is a pleiotropic pro-inflammatory and immunomodulatory cytokine which probably plays an important role in the pathogenesis of chronic obstructive pulmonary disease (COPD). There is a functional single nucleotide polymorphism (SNP), -174G/C, in the promoter region of IL6. It was hypothesised that IL6 SNPs influence susceptibility for impaired lung function and COPD in smokers. Seven and five SNPs in IL6 were genotyped in two nested case-control samples derived from the Lung Health Study (LHS) based on phenotypes of rate of decline of forced expiratory volume in 1 s (FEV(1)) over 5 years and baseline FEV(1) at the beginning of the LHS. Serum IL6 concentrations were measured for all subjects. A partially overlapping panel of nine IL6 SNPs was genotyped in 389 cases of COPD from the National Emphysema Treatment Trial (NETT) and 420 controls from the Normative Aging Study (NAS). In the LHS, three IL6 SNPs were associated with decline in FEV(1) (0.023< or =p< or =0.041 in additive models). Among them, the IL6_-174C allele was associated with a rapid decline in lung function. The association was more significant in a genotype-based analysis (p = 0.006). In the NETT-NAS study, IL6_-174G/C and four other IL6 SNPs, all of which are in linkage disequilibrium with IL6_-174G/C, were associated with susceptibility to COPD (0.01< or =p< or =0.04 in additive genetic models). The results suggest that the IL6_-174G/C SNP is associated with a rapid decline in FEV(1) and susceptibility to COPD in smokers.

IL6 genotype and creatine kinase response to exercise

Dear Editor, Yamin and colleagues recently reported an association of a common single nucleotide polymorphisms (SNP) in the promoter region of interleukin-6 (IL6) gene creating a change from a G to C at position -174, and that of tumor necrosis alpha (TNF) gene creating a change from a G to A at position -308 with systemic creatine kinase response to eccentric exercise (Yamin et al. 2008). Previously, Olomolaiye et al. (1998) described that the presence of allele C of the IL6 SNP -174 creates a restriction site for NlaIII, and Fishman et al. (1998) further investigated the eVect of this SNP on IL6 promoter activity and also genotyped healthy Caucasian subjects and patients with juvenile chronic arthritis. However, in the paper Yamin et al. (2008) erroneously refer to this polymorphism with a NCBI reference SNP ID rs13447445, which is in fact located at position -61 of the IL6 gene, and not at position -174 with an ID rs1800795. Similarly, the TNF SNP -308 investigated by the authors should be referred with rs1800629, and not with rs361525 which is located at position -238. Furthermore, the authors describe that they ampliWed a region for genotyping with NlaIII digestion although this genomic region contains the two IL6 SNPs (rs1800795 and rs13447445) that share a G to C transition, thus creating multiple sites for NlaIII, in addition to an internal site at location -293 to -296. Hence this raises a concern and argues whether the relatively low frequency for genotype CC reported (0.03) (Yamin et al. 2008) can rather be explained by technical limitations of the assay or data interpretation than true characteristics of the population investigated. Fortunately, genotyping assays are available that can better overcome such potential pitfalls (Marras et al. 1999; Sylvain et al. 2004). Nevertheless, it is imperative that the authors address this for their data interpretation as it may otherwise leave the reported association of IL6 -174 SNP on eccentric exercise-associated creatine kinase response unrevealed.

Interleukin 10 (IL‐10) gene variants and susceptibility for paediatric onset Crohn’s disease

A recent genome-wide association study in adult patients with ulcerative colitis (UC) has implicated the interleukin 10 (IL-10) gene as an important candidate gene. Moreover, a UC-associated single nucleotide polymorphism (SNP) rs3024405 was also significantly associated with adult Crohn's disease (CD). To examine whether IL-10-CD associations extended to paediatric-onset CD. We implemented the case-control design at three paediatric gastroenterology clinics in Canada. CD patients (<or=20 years) were recruited along with healthy controls. DNA samples were genotyped for tag-single nucleotide polymorphisms (tag-SNPs) in the IL-10 gene. Allelic, genotype and haplotype associations with CD were studied. A total of 270 patients and 336 controls were studied. The mean age (+/-s.d.) at diagnosis was 12.1 (+/-3.5). There were a slightly higher proportion of male patients (56.3%). Of the five IL-10 tag-SNPs, rs2222202 (C/T) (P = 0.03) and rs1800871 (C/T) (P = 0.05) showed significant allelic associations with CD. Specific IL-10 SNPs were associated with CD disease location and/or disease behaviour. Our gene-wide analysis replicates recent findings of associations between IL-10 and adult CD, and suggests that these associations extend to paediatric-onset CD as well.

Impact of Interleukin-10 Gene Promoter Polymorphisms on Clinical Course of Chronic Lymphocytic Leukemia

Background: Interleukin-10 (IL-10) is an important immunoregulatory cytokine modulating the balance between cell-mediated and humoral response. It has been suggested that dysregulation and different IL-10 level resulting from single-nucleotide polymorphisms (SNPs) in IL-10 gene promoter play a role in pathogenesis of lymphoid disorders, and may increase a risk of non-Hodgkin lymphomas (NHL) development, especially diffuse large B-cell lymphoma subtype. The aim of this study was to investigate whether functionally important IL-10 promoter region SNPs IL-10: −1082A>G and IL-10: − 3575T>A contribute to the incidence and clinical course of B-cell chronic lymphocytic leukemia (CLL).Patients and Methods: We genotyped IL-10: −1082A>G and IL-10: − 3575T>A SNPs in 85 patients with B-CLL and 94 ethnically-matched healthy individuals by direct sequencing using 3130xl Genetic Analyzer (Applied Biosystems). Sequence data were based on the NCI SNP500 website http://snp500cancer.nci.nih.gov. Haplotype analysis was performed using version 2.0.2 PHASE software (http://www.stat.Washington.edu/stephens/). For the clinical features, p values were calculated using χ2 test. Survival probabilities were estimated using the Kaplan-Meier method and comparison of survival was based on log-rank testing.Results: The IL-10: −1082A>G or IL-10: −3575T>A allelic frequencies and distributions were consistent with Hardy-Weinberg equilibrium, and did not differ significantly between CLL patients and the control group. Four distinct haplotypes, including IL-10: −1082G, −3575A, IL-10: −1082A, −3575T, IL-10: −1082G, − 3575T, and IL-10: −1082A, −3575A, inferred in healthy controls and CLL patients. There were no significant differences in estimated frequencies of these haplotypes between CLL patients and controls. No association was found between IL-10: −1082A>G or IL-10: − 3575T>A allelic, genotype or haplotype distribution and clinical characteristics of CLL patients at diagnosis, including age, clinical stage according to Rai classification, surface CD38 expression, serum LDH and β2-microglobulin levels. In patients with IL-10: − 1082G allele (IL-10: −1082GG or IL-10: −1082GA genotypes) there was a trend towards higher frequency of autoimmune complications during CLL course as compared to those carrying IL-10: −1082AA genotype (13% vs 0%, p=0.04, χ2 test). The patients with IL-10: −1082G allele had significantly shorter time from diagnosis to treatment (log-rank test, p=0.02) as compared to individuals carrying IL-10: −1082AA genotype. However, neither of assessed IL-10 SNPs was associated with response to first-line treatment or freedom from progression time. With a median follow-up of surviving patients of 80 months (range 8–209), no correlation was found between IL-10: −1082A>G or IL-10: −3575T>A alleles, genotypes or haplotypes and overall survival in CLL patients.Conclusions: The study suggests the influence of IL-10: −1082G allele, predisposing to higher IL-10 production, on activation of immune system towards more aggressive course of CLL requiring earlier treatment intervention. Similarly to other low-grade NHL studies, our findings did not support an important role of IL-10 SNPs in CLL occurrence and survival however larger studies are needed to confirm these results.

Influence of Host Interleukin-10 Polymorphisms on Development of Traveler's Diarrhea Due to Heat-Labile Enterotoxin-ProducingEscherichia coliin Travelers from the United States Who Are Visiting Mexico

Up to 60% of U.S. visitors to Mexico develop traveler's diarrhea (TD), mostly due to enterotoxigenic Escherichia coli (ETEC) strains that produce heat-labile (LT) and/or heat-stable (ST) enterotoxins. Distinct single-nucleotide polymorphisms (SNPs) within the interleukin-10 (IL-10) promoter have been associated with high, intermediate, or low production of IL-10. We conducted a prospective study to investigate the association of SNPs in the IL-10 promoter and the occurrence of TD in ETEC LT-exposed travelers. Sera from U.S. travelers to Mexico collected on arrival and departure were studied for ETEC LT seroconversion by using cholera toxin as the antigen. Pyrosequencing was performed to genotype IL-10 SNPs. Stools from subjects who developed diarrhea were also studied for other enteropathogens. One hundred twenty-one of 569 (21.3%) travelers seroconverted to ETEC LT, and among them 75 (62%) developed diarrhea. Symptomatic seroconversion was more commonly seen in subjects who carried a genotype producing high levels of IL-10; it was seen in 83% of subjects with the GG genotype versus 54% of subjects with the AA genotype at IL-10 gene position -1082 (P, 0.02), in 71% of those with the CC genotype versus 33% of those with the TT genotype at position -819 (P, 0.005), and in 71% of those with the CC genotype versus 38% of those with the AA genotype at position -592 (P, 0.02). Travelers with the GCC haplotype were more likely to have symptomatic seroconversion than those with the ATA haplotype (71% versus 38%; P, 0.002). Travelers genetically predisposed to produce high levels of IL-10 were more likely to experience symptomatic ETEC TD.

Interleukin-6 (IL-6) and receptor (IL6-R) gene haplotypes associate with amniotic fluid protein concentrations in preterm birth

Spontaneous preterm birth (PTB-gestational age <37 weeks) occurs in approximately 450 000 births annually in the United States and is one of the leading causes of neonatal morbidity and mortality. Risk of PTB is affected by complex gene-environment interactions that are not well understood. We examined the PTB candidate gene, Interleukin 6 (IL-6) and its receptor (IL6-R) in both Caucasian (145 PTB and 194 term maternal; 140 PTB and 179 term fetal) and African-American (76 PTB and 191 term maternal; 66 PTB and 183 term fetal) DNA. Eight single nucleotide polymorphisms (SNPs) in IL-6 and 22 SNPs in IL6R were examined for association with IL-6 amniotic fluid (AF) concentrations, as concentration of IL-6 is a hypothesized risk factor. In addition, IL-6 and IL6-R SNPs were analyzed for associations with PTB. Haplotype associations were tested by sliding windows. No strong single marker effects were observed in Caucasians; however, in African-American maternal IL-6R marker rs4553185 associated with PTB (allele P = 4.49 x 10(-3) and genotype P = 0.01). The strongest haplotype associations were observed in IL-6R with IL-6 cytokine concentration as outcome: Caucasian fetal (rs4601580-rs4845618) P = 1.6 x 10(-3) and African-American maternal (rs4601580-rs4845618-rs6687726-rs7549338) P = 2.30 x 10(-3). Significant results converged on three regions in the two genes: in IL-6 markers rs1800797, rs1800796 and rs1800795; in IL-6R markers rs4075015, rs4601580, rs4645618, rs6687726 and rs7549338 and markers rs4845623, rs4537545 and rs4845625. In conclusion, our results suggest that IL-6 AF concentration, in situations of PTB, result from variation in IL-6 and more importantly IL-6R.

Interleukin-10 and Tumor Necrosis Factor-α Polymorphisms in Vascular Access Failure in Patients on Hemodialysis: Preliminary Data in Korea

Neointimal hyperplasia causes vascular stenosis and subsequent thrombosis, which result in vascular access failure in patients undergoing hemodialysis. Interleukin-10 (IL-10) and tumour necrosis factor-α (TNF-α ) are involved in this inflammatory process. The aim of this study was to investigate the relationship between vascular accessm failure and various inflammatory markers including the genetic polymorphisms of IL-10 and TNF-α . Seventy-five patients on hemodialysis with an arteriovenous fistula in place or an artificial graft (18 with vascular access failure and 82 without failure) and 98 healthy individuals were genotyped for IL-10 and TNF-α single nucleotide polymorphisms. Clinical and laboratory data including serum IL-10 and TNF-α levels were compared. Stimulated IL-10 levels, from in vitro incubation of blood with lipopolysaccharide, were also obtained and compared. Female gender, hypoproteinemia, and hypertriglyceridemia were associated with vascular access failure. The basal TNF-α level was significantly higher in patients with access failure. The distribution of IL-10 and TNF-α genotype did not differ among patients with or without access failure. This study could not demonstrate a relationship between genetic polymorphisms and vascular access failure. However, an altered immune response and inflammation might contribute to vascular access failure.

C/G homozygotes of interleukin-6 single nucleotide polymorphism at -572 are associated with nonalcoholic steatohepatitis

C/G homozygotes of interleukin-6 single nucleotide polymorphism at -572 are associated with nonalcoholic steatohepatitis

Impact of interleukin-10 polymorphisms ( 1082 and 3575) on the survival of patients with lymphoid neoplasms

Single-nucleotide polymorphisms (SNP) in interleukin-10 (IL-10) genes can influence immune responses, which may affect the outcome of patients with lymphoid neoplasms. The aim of this study was to explore the association between polymorphisms of IL-10-(1082A>G) and IL-10-(3575T>A) with the overall survival in patients with lymphoid neoplasms. We analyzed two IL-10 SNP (-1082 and -3575) in 472 consecutive cases with lymphoid neoplasms. Genotypes were tested for association with overall survival and classical prognostic factors by multivariate analysis. Haplotype analysis was carried out using the haplostats package implemented in R software. The implications for survival of patients with lymphoma were evaluated using multivariate analysis. Lymphoma patients with the IL-10-(3575T>A) genotype had a better overall survival (p= 0.002), as did the subgroup with non-Hodgkin's lymphoma (NHL) (p=0.05). Patients with the IL10(-1082GG) genotype had a better median overall survival (p=0.05). When both genotypes were included in a multivariate analysis, IL-10(-3575AA) genotype was the only independent prognostic factor for survival (HR=0.20, 95%CI 0.05-0.92). Patients with the IL-10(-1082) and (-3575) G-A/G-A diplotype had a longer overall survival (p=0.003) and this combination appeared to be an independent prognostic factor for survival (HR:0.26; 95%CI 0.08-0.83). The IL-10(-3575A/A) genotype was identified as a marker of favorable survival. Because the IL-10(-1082) and (-3575) G-A/G-A diplotype was also identified as an indicator of longer survival, we cannot exclude the potential additive role of the IL-10(-1082GG) genotype. These results need to be replicated in larger series and examined in different NHL subtypes.

Short Communication Single nucleotide polymorphisms in five adipokine genes in dairy cattle populations

Genetic diversity in candidate genes for fitness and production traits was explored in three populations of dairy cattle. The study focused on adipokines, including leptin (LEP), tumor necrosis factor alpha (TNF), interleukin-8 (IL8) and interleukin-10 (IL10) as candidate genes. The three populations of interest included young Jersey and Holstein (modern Holstein) sires, and Holstein sires born prior to 1970 (traditional Holstein). Pools of DNA representing each sire group were used as template to generate PCR products for sequencing and identification of single nucleotide polymorphisms (SNP). Sequences of PCR products were assembled and SNPs identified using Sequencher 4.5 software. One SNP representing each gene and a previously reported SNP in LEP were selected for genotyping across all bulls. A multiplexed genotyping assay was developed using the ABI PRISM SNaPshot Multiplex Kit. Allele and genotypic frequencies were determined for each sire group, and genotypic frequencies were in agreement with Hardy-Weinberg equilibrium. Allele frequencies were compared among sire groups using the chi-square test. A significant difference between Jersey and Holstein was observed for all genes, and modern and traditional Holstein groups differed for the previously described LEP and IL10 SNP. Although allele frequency differences between modern and traditional Holsteins may reflect the effect of selection pressure for production traits on these genomic regions, random genetic drift or sampling bias could also have contributed to the observed differences. Keywords: Fitness traits; genetic markers; adipokines; dairy cattle South African Journal of Animal Science Vol. 37 (3) 2007: pp.154-157

Is Elevated Serum IL-10 in B-CLL Associated with IL-10 Promoter Polymorphisms?.

Interleukin-10 (IL-10), a cytokine that regulates inflammation, may play an important role in B-cell chronic lymphocytic leukemia (B-CLL), because of the reported association of high serum IL-10 levels with a lower prognosis of survival. Using the Bio-Plex protein array system, we confirmed that B-CLL patients exhibit higher median IL-10 levels (3.54 pg/ml, n=50) as compared to controls (1.28 pg/ml, n=33) (p<0.0001). We are in the midst of determining B-CLL VH gene mutation status and IL-10 levels. To determine if elevated IL-10 levels are due to inherent genetic polymorphisms, we examined three single nucleotide polymorphisms (SNPs) in the proximal end of the promoter region of the IL-10 gene (-1082 A/G, −819 T/C, and −592 A/C) that may affect IL-10 transcription levels. DNA from an overlapping set of 54 B-CLL patients and 48 normals was genotyped using the Transgenomic WAVE system. The difference in allele frequencies at a single locus showed no trend towards significance between groups using the Pearsons chi-square test and Odds Ratios (OR) with 95% Confidence Intervals (CI) for each SNP (-1082 (p = 0.686, OR = 1.122, CI = 0.641–1.966), −819 (p = 0.844, OR = 1.062, CI = 0.585–1.926) and −592 (p = 0.720, OR = 1.116, CI = 0.613–2.031)). B-CLL cases and normal subjects showed no significant departure from Hardy-Weinberg equilibrium in single locus genotype frequencies. Differences in single locus genotype frequencies between B-CLL cases and controls showed no significant differences for each SNP (−1082 (p = 0.600, OR = 1.366, CI = 0.425–4.389), −819 (p = 0.638, OR = 0.727, CI = 0.192–2.749), and −592 (p = 0.638, OR = 0.727, CI = 0.192–2.749)). The haplotype frequencies were calculated using maximum likelihood method based on the observed genotypes. The differences in maximum likelihood haplotype frequencies, between the B-CLL cases and controls, were insignificant (p = 0.754). The haplotype pair genotype frequency differences between the B-CLL cases and controls were also insignificant (p = 0.921). In conclusion, the allele, genotype, and haplotype frequencies of IL-10 SNPs −1082, −819, and −592 show no trend towards significance overall. This suggests that these promoter SNPs do not contribute to elevated serum IL-10 in B-CLL. However, a suggestion of association with VH gene mutation status is being further investigated with a larger sample size.

Genetics of Type 2 Diabetes: Impact of Interleukin-6 Gene Variants

The KORA studies serve as a powerful tool for the genetic analysis of complex diseases like type 2 diabetes or the metabolic syndrome. These studies include more than 2,000 prevalent and incident type 2 diabetes cases. DNA of these patients is available to be used in genetic studies. Up to now the analyses have focussed on genes coding for proteins being involved in the inflammatory response. Interleukin-6 (IL-6) as the key mediator of the acute phase reaction is of interest. Elevated protein concentrations of IL-6 in the blood have been shown to predict type 2 diabetes. We investigated the association of the IL-6 single nucleotide polymorphism (SNP) C-174G with type 2 diabetes in a case-control study of 704 elderly participants of the KORA Survey S4 (1999/2001). When BMI, HDL cholesterol, physical activity, hypertension, hormone replacement therapy and smoking were considered as covariables the SNP C-174G showed a trend for association with type 2 diabetes (- 174G: OR 1.20, 95 % CI 0.90 - 1.59, p = 0.21).

Association tests of interleukin-6 (IL-6) and type II tumor necrosis factor receptor (TNFR2) genes with bone mineral density in Caucasians using a re-sampling approach

Interleukin 6 (IL-6) and tumor necrosis factor (TNF) are important cytokines for bone turnover. In this study, a promoter C-174G single-nucleotide polymorphism (SNP) within the IL-6 gene affecting the transcription rate of IL-6 and an exon 6 T676G SNP of the TNF receptor 2 (TNFR2) gene causing an M196R amino-acid change were examined for their relationship with bone mineral density (BMD). Four hundred and five multi-offspring Caucasian families, including 389 male children and 744 female children, were used. One thousand re-samplings were conducted and in each data set, one child was randomly chosen from each family. For each data set, one-way analysis of variance (ANOVA) test was independently implemented using age, age2, sex, height and weight as covariates. There were 523, 288, 204 and 369 significant results out of 1,000-replicate re-samplings of the data of the IL-6 SNP (P<0.05) for one-third, mid-distal, ultradistal radius BMD, and the first principal component (PC1) extracted from the three radial BMDs, respectively, which means that the confidences for associations of the C-174G SNP in the IL-6 gene with one-third, mid-distal, ultradistal radius (totally called distal forearm) BMDs, and PC1, were 52.3, 28.8, 20.4 and 36.9%, respectively. For this SNP with BMD at other skeletal sites and the TNFR2 T676G SNP with BMD at any site, significant results were far less than 200 times out of 1,000 re-sampling replicates. The exceedingly consistent permutation results further improved the confidence of the associations. It may imply that the IL-6 C-174G SNP is associated with distal forearm BMD, but there is no evidence that the TNFR2 T676G SNP is related with BMD in US Caucasians. This is the first attempt to conduct association test utilizing a re-sampling approach. Our results may be more informative than other association analyses that were only based on one sampling result. The results also suggest that different samplings could produce significantly diverse results even for the same population and the results from one sampling are unlikely to be conclusive. Our results have significant implications for association studies and interpretation of non-reproducible association findings.

Risk of trachomatous scarring and trichiasis in Gambians varies with SNP haplotypes at the interferon-gamma and interleukin-10 loci

Experimental evidence implicates interferon gamma (IFNgamma) in protection from and resolution of chlamydial infection. Conversely, interleukin 10 (IL10) is associated with susceptibility and persistence of infection and pathology. We studied genetic variation within the IL10 and IFNgamma loci in relation to the risk of developing severe complications of human ocular Chlamydia trachomatis infection. A total of 651 Gambian subjects with scarring trachoma, of whom 307 also had potentially blinding trichiasis and pair-matched controls with normal eyelids, were screened for associations between single-nucleotide polymorphisms (SNPs), SNP haplotypes and the risk of disease. MassEXTEND (Sequenom) and MALDI-TOF mass spectrometry were used for detection and analysis of SNPs and the programs PHASE and SNPHAP used to infer haplotypes from population genetic data. Multivariate conditional logistic regression analysis identified IL10 and IFNgamma SNP haplotypes associated with increased risk of both trachomatous scarring and trichiasis. SNPs in putative IFNgamma and IL10 regulatory regions lay within the disease-associated haplotypes. The IFNgamma +874A allele, previously linked to lower IFNgamma production, lies in the IFNgamma risk haplotype and was more common among cases than controls, but not significantly so. The promoter IL10-1082G allele, previously associated with high IL10 expression, is in both susceptibility and resistance haplotypes.

Interaction of polymorphisms in the genes encoding interleukin‐6 and estrogen receptor beta on the susceptibility to Parkinson's disease

The multifunctional cytokine interleukin-6 (IL-6) is involved in inflammatory processes in the central nervous system and increased levels of IL-6 have been found in patients with Parkinson's disease (PD). It is known that estrogen inhibits the production of IL-6, via action on estrogen receptors, thereby pointing to an important influence of estrogen on IL-6. In a previous study, we reported an association between a G/A single nucleotide polymorphism (SNP) at position 1730 in the gene coding for estrogen receptor beta (ERbeta) and age of onset of PD. To investigate the influence of a G/C SNP at position 174 in the promoter of the IL-6 gene, and the possible interaction of this SNP and the ERbeta G-1730A SNP on the risk for PD, the G-174C SNP was genotyped, by pyrosequencing, in 258 patients with PD and 308 controls. A significantly elevated frequency of the GG genotype of the IL-6 SNP was found in the patient group and this was most obvious among patients with an early age of onset (</=50 years) of PD. When the GG genotypes of the IL-6 and ERbeta SNPs were combined, the combination was much more robustly associated with PD, and especially with PD with an early age of onset, than respective GG genotype when analyzed separately. Our results indicate that the G-174C SNP in the IL-6 promoter may influence the risk for developing PD, particularly regarding early age of onset PD, and that the effect is modified by interaction of the G-1730A SNP in the ERbeta gene.