Genetic variation in IL6 gene and type 2 diabetes: tagging-SNP haplotype analysis in large-scale case-control study and meta-analysis

Redefining copy number variation and single-nucleotide polymorphism counting via novel concepts based on recent PCR enhancements

Human genes have numerous copy number variations (CNVs) and single-nucleotide polymorphisms (SNPs) that control most of the body's core functions. On average, 12-16 % of human genes have CNVs, and a single gene can have a few hundred to several thousand SNPs. Numerous genome-wide association studies (GWAS) have shown that CNVs and SNPs can coexist in certain genomic regions, amplifying their effects on gene expression and regulation and disease susceptibility. Researchers initially categorized CNVs and SNPs into two types: homozygous and heterozygous. However, copy numbers were soon found to have a much wider range, underscoring their significance in certain diseases and microbial interactions. Because of the significant impact of CNVs and SNPs, research groups worldwide have eagerly sought effective methods for detecting both simultaneously. Despite yielding some minor results, these simultaneous counting methods have failed to meet expectations, leaving researchers to measure CNVs and SNPs separately. To overcome these limitations, we developed a novel approach by combining primers designed using the STexS method with matching probes used in the STexS II method. This method successfully detected both CNVs and SNPs in CYP2A6 and CYP2A7 using a single quantitative polymerase chain reaction. Once properly adjusted based on the three core principles, this new method markedly improved the time, cost-effectiveness, and overall accuracy of determining an individual's genetic status. Further testing of 100 human genomic DNA samples enabled calculations of the overall frequency of the [T] and [G] alleles of the CYP2A6 -48T > G SNP within an East Asian population yielded results that were highly congruent with those in a National Institutes of Health (NIH) database. This novel method will redefine genetic profiling and provide a means to successfully predict genetic characteristics and enhance personalized medicine by pinpointing appropriate individualized treatments.

In-silico analysis predicts disruption of normal angiogenesis as a causative factor in osteoporosis pathogenesis

Angiogenesis-osteogenesis coupling is critical for proper functioning and maintaining the health of bones. Any disruption in this coupling, associated with aging and disease, might lead to loss of bone mass. Osteoporosis (OP) is a debilitating bone metabolic disorder that affects the microarchitecture of bones, gradually leading to fracture. Computational analysis revealed that normal angiogenesis is disrupted during the progression of OP, especially postmenopausal osteoporosis (PMOP). The genes associated with OP and PMOP were retrieved from the DisGeNET database. Hub gene analysis and molecular pathway enrichment were performed via the Cytoscape plugins STRING, MCODE, CytoHubba, ClueGO and the web-based tool Enrichr. Twenty-eight (28) hub genes were identified, eight of which were transcription factors (HIF1A, JUN, TP53, ESR1, MYC, PPARG, RUNX2 and SOX9). Analysis of SNPs associated with hub genes via the gnomAD, I-Mutant2.0, MUpro, ConSurf and COACH servers revealed the substitution F201L in IL6 as the most deleterious. The IL6 protein was modeled in the SWISS-MODEL server and the substitution was analyzed via the YASARA FoldX plugin. A positive ΔΔG (1.936) of the F201L mutant indicates that the mutated structure is less stable than the wild-type structure is. Thirteen hub genes, including IL6 and the enriched molecular pathways were found to be profoundly involved in angiogenesis/endothelial function and immune signaling. Mechanical loading of bones through weight-bearing exercises can activate osteoblasts via mechanotransduction leading to increased bone formation. The present study suggests proper mechanical loading of bone as a preventive strategy for PMOP, by which angiogenesis and the immune status of the bone can be maintained. This in silico analysis could be used to understand the molecular etiology of OP and to develop novel therapeutic approaches.

Association between Interleukin-6 Gene Polymorphism (rs1800795 and rs1800796) and Type 2 Diabetes Mellitus in a Ghanaian Population: A Case-Control Study in the Ho Municipality

Background

There is no conclusive evidence on the association between interleukin- (IL-) 6 gene polymorphism and type 2 diabetes mellitus (type 2 DM). Thus, this study is aimed at evaluating the role of rs1800795 and rs1800796 polymorphisms in the pathogenesis of type 2 DM among Ghanaians in the Ho Municipality.

Materials and Methods

We recruited into this hospital-based case-control study 174 patients with type 2 DM (75 DM alone and 99 with DM+HTN) and 149 healthy individuals between 2018 and 2020. Demographic, lifestyle, clinical, anthropometric, and haemodynamic variables were obtained. Fasting blood samples were collected for haematological, biochemical, and molecular analyses. Genomic DNA was extracted, amplified using Tetra-primer amplification refractory mutation system-polymerase chain reaction (T-ARMS-PCR) technique, and genotyped for IL-6 gene polymorphism. Logistic regression analyses were performed to assess the association between IL-6 gene polymorphism and type 2 DM.

Results

The minor allele frequency (MAF) of the rs1800795 and rs1800796 polymorphisms was higher in DM alone (57.5%, 62.0%) and DM with HTN groups (58.3%, 65.3%) than controls (33.1%, 20.0%). Carriers of the rs1800795GC genotype (aOR = 2.35, 95% CI: 1.13-4.90, p = 0.022) and mutant C allele (aOR = 2.41, 95% CI: 1.16-5.00, p = 0.019) as well as those who carried the rs1800796GC (aOR = 8.67, 95% CI: 4.00-18.90, p < 0.001) and mutant C allele (aOR = 8.84, 95% CI: 4.06-19.26, p = 0.001) had increased odds of type 2 DM. For both polymorphisms, carriers of the GC genotype had comparable levels of insulin, HOMA-IR, and fasting blood glucose (FBG) with those who carried the GG genotype. IL-6 levels were higher among carriers of the rs1800796GC variant compared to carriers of the rs1800796GG variant (p = 0.023). The rs1800796 polymorphism, dietary sugar intake, and exercise status, respectively, explained approximately 3% (p = 0.046), 3.2% (p = 0.038, coefficient = 1.456), and 6.2% (p = 0.004, coefficient = -2.754) of the variability in IL-6 levels, suggesting weak effect sizes.

Conclusion

The GC genotype and mutant C allele are risk genetic variants associated with type 2 DM in the Ghanaian population. The rs1800796 GC variant, dietary sugar intake, and exercise status appear to contribute significantly to the variations in circulating IL-6 levels but with weak effect sizes.

Cytokine Gene Polymorphisms in Patients with Chronic Inflammatory Demyelinating Polyneuropathy

Innate and adaptive immune responses exert their role in CIDP pathogenesis through cytokine production. Single-nucleotide polymorphisms (SNPs) may alter cytokine gene expression, with a potential influence on the pathogenesis of autoimmune diseases. However, cytokine gene SNPs have not been assessed in CIDP patients yet. We assessed functional SNPs in the genes encoding IL-10 (rs1800896, rs1800871, rs1800872 and rs3024505), IL-6 (rs1800795), TNF (rs1800629 and rs361525), IL-12B (rs3212227), IFN-γ (rs2430561), GM-CSF (rs25882) and IL-17F (rs11465553) in a cohort of 88 CIDP patients and 486 healthy controls (HCs) via qPCR. We found an association of SNP in the IL10 promotor and CIDP occurrence. Major homozygotes (AA) were more frequent in the HCs compared to CIDP patients (p = 0.049), but the GA genotype prevailed among the patients (p = 0.032). A lower frequency of the C allele was observed for rs1800871 and rs1800872 in CIDP patients compared to the HCs (p = 0.048). A higher proportion of A carriers at position -1082 (rs1800896) (presumed to be a low IL-10 producer) was noted in patients with milder disability (low INCAT). All mild-INCAT patients were C carriers for rs1800871 and rs1800872 in IL10 (p = 0.038). Furthermore, the IL6 rs1800795 GG genotype was more frequent in patients (p = 0.049) and the CG heterozygote in the HCs (p = 0.013). Among the CIDP patients, being a G carrier for this SNP was associated with a higher frequency of type 2 diabetes (T2D) compared to being a non-carrier (p = 0.032). Our data indicate a possible association of the IL10 and IL6 SNPs with CIDP, but also with disease severity and T2D occurrence. Given the paucity of CIDP patients, multicentric studies are necessary to draw definite conclusions on these associations.

Cytokine pathway variants modulate platelet production: IFNA16 is a thrombocytosis susceptibility locus in humans

Inflammatory stimuli have divergent effects on peripheral platelet counts, although the mechanisms of thrombocytopenic and thrombocytotic responses remain poorly understood. A candidate gene approach targeting 326 polymorphic genes enriched in thrombopoietic and cytokine signaling pathways was applied to identify single nucleotide variants (SNVs) implicated in enhanced platelet responses in cohorts with reactive thrombocytosis (RT) or essential (myeloproliferative neoplasm [MPN]) thrombocytosis (ET). Cytokine profiles incorporating a 15-member subset, pathway topology, and functional interactive networks were distinct between ET and RT, consistent with distinct regulatory pathways of exaggerated thrombopoiesis. Genetic studies using aggregate (ET + RT) or ET-restricted cohorts identified associations with 2 IFNA16 (interferon-α16) SNVs, and the ET associations were validated in a second independent cohort (P = .0002). Odds ratio of the combined ET cohort (n = 105) was 4.92, restricted to the JAK2V617F-negative subset (odds ratio, 5.01). ET substratification analysis by variant IFNA16 exhibited a statistically significant increase in IFN-α16 levels (P = .002) among 16 quantifiable cytokines. Recombinantly expressed variant IFN-α16 encompassing 3 linked non-synonymous SNVs (E65H95P133) retained comparable antiviral and pSTAT signaling profiles as native IFN-α16 (V65D95A133) or IFN-α2, although both native and variant IFN-α16 showed stage-restricted differences (compared with IFN-α2) of IFN-regulated genes in CD34+-stimulated megakaryocytes. These data implicate IFNA16 (IFN-α16 gene product) as a putative susceptibility locus (driver) within the broader disrupted cytokine network evident in MPNs, and they provide a framework for dissecting functional interactive networks regulating stress or MPN thrombopoiesis.

Empowering consumers to PREVENT diet-related diseases through OMICS sciences (PREVENTOMICS): protocol for a parallel double-blinded randomised intervention trial to investigate biomarker-based nutrition plans for weight loss

INTRODUCTION

Personalised nutrition holds immense potential over conventional one-size-fits-all approaches for preventing and treating diet-related diseases, such as obesity. The current study aims to examine whether a personalised nutritional plan produces more favourable health outcomes than a standard approach based on general dietary recommendations in subjects with overweight or obesity and elevated waist circumference.

METHODS AND ANALYSIS

This project is a 10-week parallel, double-blinded randomised intervention trial. We plan to include 100 adults aged 18-65 years interested in losing weight, with body mass index ≥27 but<40 kg/m² and elevated waist circumference (males >94 cm; females >80 cm). Participants will be categorised into one of five predefined 'clusters' based on their individual metabolic biomarker profile and genetic background, and will be randomised in a 1:1 ratio to one of two groups: (1) personalised plan group that will receive cluster-specific meals every day for 6 days a week, in conjunction with a personalised behavioural change programme via electronic push notifications; or (2) control group that will receive meals following the general dietary recommendations in conjunction with generic health behaviour prompts. The primary outcome is the difference between groups (personalised vs control) in the change in fat mass from baseline. Secondary outcomes include changes in weight and body composition, fasting blood glucose and insulin, lipid profile, adipokines, inflammatory biomarkers, and blood pressure. Other outcomes involve measures of physical activity and sleep patterns, health-related quality of life, dietary intake, eating behaviour, and biomarkers of food intake. The effect of the intervention on the primary outcome will be analysed by means of linear mixed models.

ETHICS AND DISSEMINATION

The protocol has been approved by the Ethics Committee of the Capital Region, Copenhagen, Denmark. Study findings will be disseminated through peer-reviewed publications, conference presentations and media outlets.

TRIAL REGISTRATION NUMBER

NCT04590989.

Meta-analysis: Interleukin 6 gene -174G/C polymorphism associated with type 2 diabetes mellitus and interleukin 6 changes

The gene coding interleukin 6 (IL‐6) is a promising candidate in predisposition to type 2 diabetes mellitus (T2DM). This study aimed to meta‐analytically examine the association of IL‐6 gene −174G/C polymorphism with T2DM and circulating IL‐6 changes across −174G/C genotypes. Odds ratio (OR) and standard mean difference (SMD) with 95% confidence interval (CI) were calculated. Twenty‐five articles were meta‐analysed, with 20 articles for T2DM risk and 9 articles for circulating IL‐6 changes. Overall, there was no detectable significance for the association between −174G/C polymorphism and T2DM, and this association was relatively obvious under dominant model (OR: 0.82, 95% CI: 0.56‐1.21). Improved heterogeneity was seen in some subgroups, with statistical significance found in studies involving subjects of mixed races (OR: 0.63, 95% CI: 0.46‐0.86). Begg's and filled funnel plots, along with Egger's tests revealed week evidence of publication bias. In genotype‐phenotype analyses, carriers of −174CC and −174CG genotypes separately had 0.10 and 0.03 lower concentrations (pg/mL) of circulating IL‐6 than −174GG carriers. Albeit no detectable significance for the association of −174G/C with T2DM, our findings provided suggestive evidence on a dose‐dependent relation between −174G/C mutant alleles and circulating IL‐6 concentrations, indicating possible implication of this polymorphism in the pathogenesis of T2DM.

Pharmacogenetics of Type 2 Diabetes-Progress and Prospects

Type 2 diabetes mellitus (T2D) is a chronic metabolic disease resulting from insulin resistance and progressively reduced insulin secretion, which leads to impaired glucose utilization, dyslipidemia and hyperinsulinemia and progressive pancreatic beta cell dysfunction. The incidence of type 2 diabetes mellitus is increasing worldwide and nowadays T2D already became a global epidemic. The well-known interindividual variability of T2D drug actions such as biguanides, sulfonylureas/meglitinides, DPP-4 inhibitors/GLP1R agonists and SGLT-2 inhibitors may be caused, among other things, by genetic factors. Pharmacogenetic findings may aid in identifying new drug targets and obtaining in-depth knowledge of the causes of disease and its physiological processes, thereby, providing an opportunity to elaborate an algorithm for tailor or precision treatment. The aim of this article is to summarize recent progress and discoveries for T2D pharmacogenetics and to discuss the factors which limit the furthering accumulation of genetic variability knowledge in patient response to therapy that will allow improvement the personalized treatment of T2D.

Association of interleukin-6 polymorphisms with obesity: A systematic review and meta-analysis

Obesity is a common metabolic disorder with increasing trend all around the world. Owing to the role of pro-inflammatory cytokines on obesity, we aimed to investigate the role of interleukin-6 (IL-6) polymorphisms on risk of obesity. Electronic literatures were searched in Web of Science, PubMed, Embase, and Scopus. The references of relevant reviews and included studies were also manually checked. All types of observational studies from 1 January 1992 to 28 February 2018 were included. Odds ratio (OR) was estimated by fixed and random effect model. Subgroup analysis was carried out based on age statues. Pooling analysis of eligible studies have been considered for rs2069845 and rs1800796, and no significant results were observed. Minor allele of IL-6 rs1800797polymorphism decreased the risk of obesity/overweight in allelic 0.74 (0.59-0.92), dominant 0.65 (0.49-0.85), and over-dominant 0.66 (0.51-0.87) models. Fourteen eligible studies were included for rs1800795. According to BMI, C allele showed increased risk of obesity in genetic models containing homozygote model 1.47 (1.02-2.12) for body mass index (BMI) ≥ 25 vs. BMI < 25, recessive model 1.32 (1.07-1.63) for BMI ≥ 30 vs. BMI < 25, and homozygote model 1.35 (1.10-1.66) for BMI ≥ 30 vs. BMI < 30. In overall definition of obesity more significant results were observed, including homozygote model in obese vs. normal 1.71 (1.14-2.56). Similarly, subgroups analysis revealed additional significant results. Minor alleles of rs1800795 raised and rs1800797 reduced the risk of obesity, while rs1800796 and rs2069845 may not be associated. However, more observational studies are recommended to confirm these results.

Association Between IL-6 Polymorphisms and Diabetic Nephropathy Risk: A Meta-analysis

BACKGROUND

The objective of this work was to evaluate the relevance of frequent interleukin-6 (IL-6) polymorphisms and diabetic nephropathy (DN) susceptibility by a systematic meta-analysis.

MATERIALS AND METHODS

The included studies related to the relationship between IL-6 and DN risk were searched from Pubmed, Embase and the Cochrane Library, and the Newcastle-Ottawa Scale was used to evaluate the study quality. A heterogeneity test was performed to determine the appropriate effect models based on the Q test and I² statistic. Odds ratios with 95% confidence intervals were used to determine the strength of associations. Afterwards, subgroup analysis was conducted to assess the effect of specific factors on the corresponding results. Additionally, publication bias and sensitivity analysis were also undertaken.

RESULTS

In total, 11 eligible articles were obtained. The meta-analysis revealed that the "C"allele of IL-6 rs1800795 was related to the decreased risk of DN (C versus G: P = 0.0471). The "G"allele of IL-6 rs1800796 was predominately associated with higher DN risks (GG versus CC: P = 0.0194; GG versus CC + GC: P = 0.0196). The "C"allele of IL-6 rs1800797 was implicated with higher prevalence of DN (C versus G: P = 0.0001; CC versus GG: P = 0.0003; CC versus GG + CG: P = 0.0227; CC + CG versus GG: P = 0.0001) while IL-6 rs2069837 and rs2069840 were not correlated with the susceptibility to DN.

CONCLUSIONS

This meta-analysis indicated that IL-6 rs1800795, rs1800796 and rs1800797 played important roles in DN development while IL-6 rs2069837 and rs2069840 might not be related to DN.

Serum profile of cytokines and their genetic variants in metabolic syndrome and healthy subjects: a comparative study

AIM

To identify genetic variants in promoter areas of IL-6 -174 G>C and TNF-α -308 G>A in metabolic syndrome (Met S) and controls and associate them with Met S and serum cytokine levels.It was a cross-sectional study, including 224 cases of Met S and 200 controls. A fasting blood sample was taken and biochemical parameters including serum glucose, insulin, lipid profile, interleukin-6 (IL-6) and tumor necrosis factor α (TNF-α) were measured. Restriction fragment length polymorphism was used to identify the genetic variants of IL-6 and TNF-α. Serum levels of IL-6 and TNF-α and insulin resistance were significantly higher in cases than the controls. IL-6 showed significant positive correlation with HOMA-IR and TNF-α. CC genotype of IL-6 was associated with the increased risk of Met S (P=0.016, OR for CC vs GC+GG = 2.33, CI: 1.15-4.71). There was no significant difference of TNF-α genotypes between the cases and the controls. Serum TNF-α and IL-6 levels were significantly higher in AA and CC genotypes of TNF-α (-308 G>A) and IL-6 (-174 G>C) as compared with the GG (P=0.00 and P=0.001). Significant correlation of IL-6 with TNF-α and insulin resistance was observed that may provide us a therapeutic target for preventing metabolic derangements from insulin resistance.

Interleukin 6 and 10 Serum Levels and Genetic Polymorphisms in Children with Down Syndrome

Immunological impairment is a condition that is often observed in individuals with Down syndrome (DS). The immune response is modulated by pro- and anti-inflammatory cytokines whose expressions could be influenced by genetic polymorphisms. The present study was aimed at evaluating the frequencies of -174G>C, -572G>C, and -597G>A polymorphisms in the interleukin 6 (IL-6) gene and -592C>A, -1082A>G, and -819C>T polymorphisms in the IL-10 gene and the IL-6 and IL-10 serum levels in healthy individuals with and without DS. The authors also aimed to investigate the impact of the genotypes on the interleukin concentrations. The genetic polymorphisms were investigated in 200 DS individuals and 200 controls without DS. The serum measurement of IL-6 and IL-10 was performed in a subgroup (54 cases and 54 controls) by enzyme-linked immunosorbent assay (ELISA). The frequencies of the polymorphisms and haplotypes evaluated were not different between individuals with and without DS. IL-10 concentration was higher in DS children but was not influenced by IL-10 gene polymorphisms. IL-6 genotypes had no influence on IL-6 serum levels. The IL-10 serum levels are increased in DS individuals, but IL-10 polymorphisms are not the main factors that influence the IL-10 expression in DS.

Association of the Interleukin-6 rs1800795 Polymorphism with Type 2 Diabetes Mellitus in the Population of the Island of Crete, Greece

BACKGROUND

Interleukin 6 (IL-6), a proinflammatory cytokine, is elevated in patients with type 2 diabetes (T2D), and is considered an independent predictor of T2D. IL-6 single-nucleotide polymorphisms (SNPs) have been associated with higher levels of IL-6. This study investigated the role of an IL-6 gene polymorphism and its possible association to T2D in the genetically homogeneous Greek population of the island of Crete.

MATERIALS AND METHODS

A total of 144 patients with T2D and 180 controls, all Cretans, selected from the Diabetes Clinic and the Department of Internal Medicine at the University Hospital of Heraklion, Crete, Greece, were genotyped for the IL-6 -174G>C (rs1800795) SNP by the restriction fragment length polymorphism method.

RESULTS

The G/C genotype and the minor allele C of the IL-6 rs1800795 SNP were more common in individuals with T2D than controls (p = 0.004, odds ratio [OR] = 1.98, 95% confidence interval [CI]: 1.24-3.18 and p = 0.011, OR = 1.59, 95% CI: 1.11-2.26, respectively).

CONCLUSION

An association of the rs1800795 SNP of the IL-6 gene with T2D has been detected for the first time in Cretans. The present results, in combination with those presented previously from different ethnic/racial populations, highlight the necessity of comparative studies among different ethnic/racial populations to detect genetic characteristics and associations with T2D.

Variants in the TNFA, IL6 and IFNG genes are associated with the dengue severity in a sample from Colombian population

Introducción. La composición genética del huésped determina, entre otros aspectos, el perfil clínico del dengue, lo cual se debería al efecto de variantes en los genes que codifican citocinas proinflamatorias.Objetivo. Evaluar la asociación entre las variantes de tres polimorfismos en los genes candidatos TNFA, IL6 e IFNG con la gravedad del dengue en una población colombiana.Materiales y métodos. Se evaluaron los polimorfismos rs1800750, rs2069843 y rs2069705 de los genes TNFA, IL6 e IFNG, respectivamente, en 226 pacientes con dengue. Los genotipos se tipificaron usando la reacción en cadena de la polimerasa (PCR) y los polimorfismos de la longitud de los fragmentos de restricción (Restriction Fragment Length Polymorphism, RFLP). Para determinar el riesgo de diferentes fenotipos del dengue, se compararon las frecuencias alélicas con la prueba de ji al cuadrado, y los genotipos y los haplotipos, con regresión logística. Por último, los análisis se ajustaron utilizando datos de autoidentificación o del componente genético ancestral.Resultados. El alelo A del rs2069843, ajustado por autoidentificación, se asoció con casos de dengue hemorrágico en afrocolombianos. En la muestra completa, dicho polimorfismo, ajustado por componente genético ancestral, fue reproducible. Además, hubo asociaciones significativas entre las combinaciones alélicas GGT y GAC de los rs1800750, rs2069843 y rs2069705 en pacientes con dengue hemorrágico, con ajuste por componente genético ancestral y sin él. Además, la combinación alélica AGC produjo 58,03 pg/ml más de interleucina 6 que la GGC, independientemente de los componentes genéticos europeo, amerindio y africano.Conclusión. Las variantes de los polimorfismos GGT y GAC de los rs1800750, rs2069843 y rs2069705 en los genes TNFA, IL6 e IFNG, respectivamente, se correlacionaron con la gravedad del dengue en esta muestra de población colombiana.

IL-6 and IL-18 cytokine gene variants of pulmonary tuberculosis patients with co-morbid diabetes mellitus and their household contacts in Hyderabad

PURPOSE

Association of cytokine genes reflects their susceptibility towards infection and disease in household contacts (HHC) of pulmonary tuberculosis (PTB) patients. Hyperglycemia, a common factor in diabetics might influence their risk towards mycobacterium tuberculosis infection and disease development. This study determines the association of IL-6 and IL-18 cytokine gene variants of TB patients with diabetes mellitus (TBDM) and their HHC in Hyderabad.

METHODS

Single nucleotide polymorphisms of IL-6 (-174 G>C and -572 G>C) and IL-18 (-137 G>C and -607 C>A) cytokine genes were genotyped by Amplification Refractory Mutation System and Restriction Fragment Length polymerase chain reaction in total of 705 subjects comprising of TBDM, their HHC, PTB, DM and Healthy controls (HC).

RESULTS

At IL-6 -174G>C variant, GG genotype, G allele in TBDM and TBDM HHC, at -572G>C variant, C allele in TBDM and GG haplotype in TBDM HHC were showing positive association, however DM have not shown any association at IL-6 polymorphic sites. With respect to the IL-18 gene polymorphisms, at -137 G>C variant, GG genotype was positively associated in PTB while at -607 C>A variant positive association was shown with AC genotype in TBDM, their HHC and DM; GACC diplotype in TBDM and GCGC in PTB.

CONCLUSION

Our findings suggest that susceptible combination of IL-6 and IL-18 cytokine genes associated with disease in the HHCs highlight their risk of inclination towards the disease.

IL-6, TNF-α, and IL-10 levels/polymorphisms and their association with type 2 diabetes mellitus and obesity in Brazilian individuals

OBJECTIVE

This study aimed to investigate the association of plasma TNF-α, IL-6, and lL-10 levels and cytokine gene polymorphisms [TNF-α (-308 G→A), IL-6 (-174 C→G) and IL-10 (-1082 A→G, -819 T→C and -592 A→C)] in type 2 diabetes mellitus (T2DM) and obese patients.

SUBJECTS AND METHODS

One hundred and two T2DM patients and 62 controls were included in this study. Cytokine plasma levels were measured by the Cytometric Bead Array method. Genotyping was carried out by the polymerase chain reaction.

RESULTS

IL-6 levels were significantly different between T2DM patients and controls. Interestingly, IL-6 levels were higher in T2DM patients with BMI > 30 kg/m2 compared with other patients and obese controls. The genotype and allele frequencies were similar between patients and controls. In the T2DM group, the SNP IL-10 -819 T/C showed a difference between the cytokine level and genotypes: IL-10 level in the TT genotype was significantly higher when compared to CC genotype.

CONCLUSIONS

These results suggest an association between IL-6 levels and obesity, and IL-10 levels and the SNP -819 T/C in T2DM. Knowledge of these variants in T2DM might contribute to a better understanding of the role of inflammation in the etiology and progression of this disease.

Association study involving polymorphisms in IL-6, IL-1RA, and CTLA4 genes and rheumatic heart disease in New Zealand population of Māori and Pacific ancestry

INTRODUCTION

Rheumatic fever (RF) incidence among New Zealand (NZ) individuals of Polynesian (Māori and Pacific) ancestry remains among the highest in the world. Polymorphisms in the IL-6, IL1RN, and CTLA4 genes have been associated with RF, and their products are modulated by new medications. Confirmation of these previous associations could help guide clinical approaches. We aimed to test IL-6, IL-1RA (IL1RN), and CTLA4 functional SNPs in 204 rheumatic heart disease (RHD) patients and 116 controls of Māori and Pacific ancestry.

MATERIAL AND METHOD

Self-reported ancestry of the eight great-grandparents defined ancestry of participants. Severity of carditis was classified according to the 2012 World Heart Federation guideline for the echocardiographic diagnosis of RHD. The IL-6 promoter rs1800797, IL1RN rs447713 and CTLA4 rs3087243 SNPs were genotyped by Taqman. Correlations were assessed by logistic regression analysis adjusting for gender and ancestry.

RESULTS

The IL-6 rs1800797 variant was significantly associated with RHD with carriers of the GG genotype 6.09 (CI 1.23; 30.23) times more likely to develop RHD than the carriers of the AA genotype (P=0.027). No significant associations with RHD were found for the IL1RN rs447713 and CTLA4 rs3087243 SNPs. Patients carrying the G allele (GG plus AG genotype) for the IL1RN rs447713 SNP had 2.36 times (CI 1.00; 5.56) more severe carditis than those without this allele (the AA genotype) (P=0.049).

CONCLUSION

The IL-6 promoter rs1800797 (-597G/A) SNP may influence susceptibility to RHD of people of Māori and Pacific ancestry living in NZ. The IL1RN rs447713 SNP may influence the severity of carditis in this population.

Waist-to-height ratio as a marker of low-grade inflammation in obese children and adolescents

BACKGROUND

The epidemic of childhood obesity is associated with early atherosclerosis. Several reports have related this event to low-grade inflammation described in obesity. CRP and IL6 are markers that correlate with adiposity. The waist-to-height ratio (WtHR) is an anthropometric marker associated with insulin resistance and inflammation. The objective of this study was to assess the correlation between WtHR, metabolic complications and pro-inflammatory factors in obese children and adolescents.

METHODS

Weight, height, waist circumference, glycemia, insulin, CRP, TNF-α and IL-6 were measured in the baseline sample in 280 patients 6-19 years of age with overweight or obesity (OW/OB) and 112 normal-weight controls. Logistic regression was performed using WtHR as an independent variable. p>0.05 STATA11.

RESULTS

Mean WtHR was 0.6±0.06 in OW/OB and 0.43±0.02 in controls (p<0.01). WtHR was increased in 93% of the OW/OB vs. 2% of the controls. In the OW/OB inflammatory markers were significantly increased (p<0.01) compared to the controls (CRP 2.2 vs. 0.8; Il-6 2.9 vs. 2.1; and TNF-α 6.2 vs. 5.5). In the WtHR>0.5, insulin resistence and inflammatory markers were significantly increased (p<0.01) compared to the WtHR<0.5 (HOMA 3.4 vs. 1.4; CRP 2.3 vs. 0.6; Il-6 2.9 vs. 2.1; and TNF-α 6.4 vs. 5.55). In logistic regression, a significant independent association was found between WtHR with CRP (OR1.47), IL6 (OR1.60) and TNF-α (OR1.79).

CONCLUSIONS

Obese children and adolescents have high inflammatory markers that may increase cardiovascular risk. WtHR is associated with low-grade inflammation and may be considered a relevant anthropometric marker in the clinical practice.

Association of IL-6 polymorphism -174G/C and metabolic syndrome in hypertensive patients

Introduction. Visceral obesity, the central core of metabolic syndrome (MetS), is conceived as the pathogenic basis of an increased cardiovascular burden and is related with changes in cytokines. We investigated whether IL-6-174G/C gene polymorphism is associated with MetS prevalence in hypertensive patients. Method. A population of hypertensive patients was included and stratified by the presence of MetS according to IDF criteria and evaluated by Framingham risk score. The IL-6-174G/C genotyping was performed by polymerase chain reaction and the prevalence of MetS was compared between “C” carrier and “non-C” carrier groups. Results. From an original sample of 664 patients, 612 (34.2% men, age 57.3 ± 10.1, 30.4% diabetics) were included. MetS was diagnosed in 51.3% of total population and “C” carriers demonstrated high prevalence of MetS (P < 0.05) and each of its components. On binary logistic regression, it was observed that the IL-6 polymorphism was independently associated with occurrence of MetS, even after adjusting for covariates (OR 1.13–2.37, 95% CI, P < 0.05). Conclusion. The C allele at the -174 locus of IL-6 gene is independently associated with the occurrence of metabolic syndrome, emphasizing the importance of inflammatory genetic background in the pathogenesis of visceral obesity and related cardiovascular burden.

Genetic polymorphisms of cytokine genes in type 2 diabetes mellitus

Diabetes mellitus is a combined metabolic disorder which includes hyperglycemia, dyslipidemia, stroke and several other complications. Various groups all over the world are relentlessly working out the possible role of a vast number of genes associated with type 2 diabetes (T2DM). Inflammation is an important outcome of any kind of imbalance in the body and is therefore an indicator of several diseases, including T2DM. Various ethnic populations around the world show different levels of variations in single nucleotide polymorphisms (SNPs). The present review was undertaken to explore the association of cytokine gene polymorphisms with T2DM in populations of different ethnicities. This will lead to the understanding of the role of cytokine genes in T2DM risk and development. Association studies of genotypes of SNPs present in cytokine genes will help to identify risk haplotype(s) for disease susceptibility by developing prognostic markers and alter treatment strategies for T2DM and related complications. This will enable individuals at risk to take prior precautionary measures and avoid or delay the onset of the disease. Future challenges will be to understand the genotypic interactions between SNPs in one cytokine gene or several genes at different loci and study their association with T2DM.

Proinflammatory and anti-inflammatory cytokines in febrile seizures and epilepsy: systematic review and meta-analysis

Activation of proinflammatory and anti-inflammatory cytokines network seems to have a role in febrile seizures (FS). The present meta-analysis was aimed to pool the inconsistent data provided with case-control studies on the relationship of proinflammatory and anti-inflammatory cytokines and FS/epilepsy risk. The genotype interleukin (IL)-1α-889 1/1 (recessive model) was significantly correlated with increased risk of epilepsy (p=0.008) and FS/epilepsy (p=0.004). Patients with IL-1β-511 T/T homozygote were more susceptible to develop FS (p=0.036) but not epilepsy. Furthermore, the T/T genotype was totally associated with increased risk of FS/epilepsy (p=0.043). Although the recessive model was also confirmed for the Asian subgroup (FS and FS/epilepsy), we found a protective effect of C/C genotype toward developing FS in the Caucasian race (p=0.020). The second meta-analysis on cytokine levels showed a statistically higher serum level of IL-6 in patients with epilepsy compared to control subjects without epilepsy. The present meta-analysis showed that two alleles of proinflammatory cytokines (IL-1α-889 and IL-1β-511) in addition to the serum concentration of IL-6 were significantly associated with FS and epilepsy or both in various subgroup analyses.

Genomics and genetics in the biology of adaptation to exercise

This article is devoted to the role of genetic variation and gene-exercise interactions in the biology of adaptation to exercise. There is evidence from genetic epidemiology research that DNA sequence differences contribute to human variation in physical activity level, cardiorespiratory fitness in the untrained state, cardiovascular and metabolic response to acute exercise, and responsiveness to regular exercise. Methodological and technological advances have made it possible to undertake the molecular dissection of the genetic component of complex, multifactorial traits, such as those of interest to exercise biology, in terms of tissue expression profile, genes, and allelic variants. The evidence from animal models and human studies is considered. Data on candidate genes, genome-wide linkage results, genome-wide association findings, expression arrays, and combinations of these approaches are reviewed. Combining transcriptomic and genomic technologies has been shown to be more powerful as evidenced by the development of a recent molecular predictor of the ability to increase VO2max with exercise training. For exercise as a behavior and physiological fitness as a state to be major players in public health policies will require that the role of human individuality and the influence of DNA sequence differences be understood. Likewise, progress in the use of exercise in therapeutic medicine will depend to a large extent on our ability to identify the favorable responders for given physiological properties to a given exercise regimen.

Variants in C-reactive protein and IL-6 genes and susceptibility to obstructive sleep apnea in children: a candidate-gene association study in European American and Southeast European populations

BACKGROUND

Preliminary evidence indicates that variants of the C-reactive protein (CRP) and IL-6 genes might be associated with the presence of obstructive sleep apnea (OSA) in childhood. Thus a candidate-gene association study was conducted to investigate the association of four variants of the CRP gene (1444C/T, -717T/C, 1861C/T, and 1919A/T) and two variants of the IL-6 gene (-174G/C and 597G/A) with OSA in a cohort of European American and Greek children.

METHODS

The genetic risk effects were estimated based on the odds ratio (OR) of the allele contrast and the generalized odds ratio (ORG), which is a model-free approach. The mode of inheritance was assessed using the degree of dominance index. The impact of haplotypes was also examined.

RESULTS

In the American population, the allele contrast and the model-free approach produced significant ORs for the CRP 1444C/T variant (OR, 3.82 [95% confidence interval {CI}, 1.91-7.63] and ORG, 4.37 [95% CI, 1.96-9.76]), respectively, and the mode of inheritance was recessiveness of allele T. Significance was also shown for the CRP 1919A/T variant (OR, 2.45 [95% CI, 1.23-4.85] and ORG, 2.76 [95% CI, 1.26-6.03]) with the mode of inheritance being nondominance of allele T. For the IL-6-174G/C variant, there was an indication of recessiveness of allele C. Finally, the IL-6-174C/IL-6 597A haplotype was associated with OSA. In the Greek population, no association was detected for any variant or haplotype.

CONCLUSIONS

Genetic variation in the IL-6/CRP pathway was associated with increased risk for OSA in European American children and may account for the higher CRP levels in the context of pediatric OSA compared to Greek children.

Association of IL-6, TNF-α and IL-10 gene polymorphisms with type 2 diabetes mellitus

Type 2 diabetes mellitus (T2DM) is a metabolic pro-inflammatory disorder characterized by chronic hyperglycemia and increased levels of circulating cytokines suggesting a causal role of inflammation in its etiology. Polymorphism of cytokine genes including interleukin-6 (IL-6), tumour necrosis factor-α (TNF-α) and interleukin-10 (IL-10) were studied in T2DM patients as well as in normal healthy controls. Genomic DNA was isolated from both T2DM patients and controls followed by quantification and genotyping by polymerase chain reaction-restriction fragment length polymorphism (PCR-RFLP) using suitable primers. The genotypic, allelic and carriage rate frequency distribution in patients and controls were analyzed by SPSS (version 15.0). Odd ratios with 95 % confidence interval was determined to describe the strength of association by logistic regression model. Double and triple combinations of genotypes were analyzed by χ(2) test. Gene-gene interaction and linkage disequilibrium tests were performed using SHEsis software. Individually, IL-6, TNF-α and IL-10 did not show any association. In double combination, IL-6 -597 GA and TNF-α -308 GG genotypes increased the risk up to 21 times and in triple combination IL-6 -597 AA, TNF-α -308 GG and IL-10 -592 CA increased the risk of T2DM up to 314 times. In gene-gene interaction allele 'A' of all studied polymorphisms increased the risk of T2DM up to 1.41 times. Our results suggest that individuals having a haplotype combination of AA, GG and CA for IL-6, TNF-α and IL-10 gene polymorphisms will have higher susceptibility and be at greater risk of developing T2DM.

Lack of an association between interleukin-6 -174G/C polymorphism and circulating interleukin-6 levels in normal population: a meta-analysis

Interleukin-6 (IL-6) signaling may play a causal role in the development of coronary heart disease. However, the relationship between IL-6 genotypes and plasma levels of IL-6 appears to be complex. To help clarify the inconsistent findings, we conducted a meta-analysis of the published genetic association studies of the -174 G/C polymorphisms in the IL-6 gene and the circulating IL-6 levels in a normal population. In this meta-analysis, no significant association of IL-6 -174G/C polymorphism and circulating IL-6 levels in a normal population was observed. However, when compared among GG, GC, and CC genotypes, heterogeneity existed among the studies. Sensitivity analysis revealed that, the independent study by Shen et al. influenced the heterogeneity in the homozygous and heterozygous comparison. Although Shen et al.'s study was excluded, no significant association was observed between IL-6 -174G/C polymorphism and circulating IL-6 levels in a normal population [homozygous comparison (GG vs. CC): the pooled standard mean difference (SMD) was -0.01, 95% confidence interval (CI): -0.1-0.08; heterozygous comparison (GC vs. GG or CC): the pooled SMD (GG vs. GC) was -0.05, 95%CI: -0.11-0.01, and the pooled SMD (CC vs. GC) was 0.03, 95%CI: -0.03-0.1]. Under the dominant model, the pooled SMD was -0.05, 95%CI: -0.11-0.01). The meta-analysis provides evidence that the -174G/C polymorphism in the IL-6 gene is not significantly associated with circulating IL-6 levels in a normal population.

Association between the interleukin-6 gene -572 C/G polymorphism and the risk of type 2 diabetes mellitus: a meta-analysis of 11,681 subjects

The association between the interleukin-6 (IL-6) gene -572 C/G (rs1800796) polymorphism and type 2 diabetes mellitus (T2DM) risk remains controversial. Thus, we performed this meta-analysis by searching PubMed, Embase, Web of Science, CBMdisc and CNKI databases until January 30, 2012. In addition, hand searching of the references of identified articles was performed. A total of 10 case-control studies including 11,681 subjects were selected to evaluate the possible association. Our results showed evidence for significant association between the IL-6 gene -572 C/G polymorphism and T2DM risk (for G allele vs. C allele: odds ratio [OR] = 1.29, 95% confidence interval [CI] = 1.09-1.52, P = 0.002, P = 0.008 after Bonferroni testing; for G/G vs. C/C: OR = 1.89, 95% CI = 1.51-2.37, P < 0.00001, P < 0.00004 after Bonferroni testing; for GG vs. G/C + C/C: OR = 1.75, 95% CI = 1.20-2.56, P = 0.004, P = 0.016 after Bonferroni testing; for G/G + G/C vs. C/C: OR = 1.32, 95% CI = 1.11-1.57, P = 0.001, P = 0.004 after Bonferroni testing). In addition, similar results were obtained in the subgroup analysis based on ethnicity. In summary, the present meta-analysis suggests a significant association between the IL-6 gene -572 G allele and increased risk of T2DM.

Comparative analysis of IL6 and IL6 receptor gene polymorphisms in mastocytosis

Mastocytosis is a rare disease with reported high interleukin-6 (IL6) levels influencing disease severity. The present study investigated polymorphisms within the genes that encode IL6 and its receptor (IL6R) in relation to mastocytosis development in a case-control design. Analysis of the IL6R Asp358Ala polymorphism showed that carriers of the AA genotype had a 2·5-fold lower risk for mastocytosis than those with the AC or CC genotypes. No association with mastocytosis was found for the IL6-174G/C polymorphism, however, it may influence the effect of IL6R polymorphism. To the best of our knowledge this is the first study analysing IL6/IL6R polymorphisms in mastocytosis.

Genetic determinants for body iron store and type 2 diabetes risk in US men and women

Background

High body iron store has been associated with an increased risk of type 2 diabetes (T2D); it remains unknown whether the genetic variants related to body iron status affect T2D risk. We aimed at comprehensively investigating the associations between the genetic variants related to body iron status and the T2D risk.

Methodology/Principal Findings

Six common SNPs related to body iron status from recent genome-wide association (GWA) studies were determined in the Nurses’ Health Study (NHS; 1,467 diabetic cases and 1,754 controls) and the Health Professionals Follow-up Study (HPFS; 1,124, diabetic cases and 1,298 controls). Plasma levels of ferritin, soluble transferrin receptor (sTfR), and transferrin were measured in NHS. Significant associations were observed for loci in TPMRSS6 with sTfR (P = 3.47×10⁻⁶), TF with transferrin (P = 0.0002 to 1.72×10⁻¹⁰); and HFE with ferritin (P = 0.017 to 1.6×10⁻⁸), sTfR (P = 0.007 to 7.9×10⁻⁶), and transferrin (P = 0.006 to 0.0007). The six SNPs together explained 5.7%, 2.7%, and 13.3% of the variation in plasma levels of ferritin, sTfR, and transferrin. After adjustment for the conventional risk factors, the T allele of SNP rs855791 in the TPMRSS6 gene was significantly associated with a 19% decreased risk of T2D (OR = 0.81; 95% CI = 0.66–0.98; P = 0.03) in men. Multiple tests attenuated this significant association to null. No associations were observed in women. SNPs at HFE and TF were not associated with diabetes risk in either sex. Dietary iron intake did not modify the associations of the newly identified loci with diabetes risk.

Conclusions/Significance

The newly identified iron-related SNP rs855791 in TPMRSS6 was nominally associated with a decreased risk of T2D in men but not in women. The apparent differences by gender warrant further study.

The role of inflammatory pathway genetic variation on maternal metabolic phenotypes during pregnancy

Background

Since mediators of inflammation are associated with insulin resistance, and the risk of developing diabetes mellitus and gestational diabetes, we hypothesized that genetic variation in members of the inflammatory gene pathway impact glucose levels and related phenotypes in pregnancy. We evaluated this hypothesis by testing for association between genetic variants in 31 inflammatory pathway genes in the Hyperglycemia and Adverse Pregnancy Outcome (HAPO) cohort, a large multiethnic multicenter study designed to address the impact of glycemia less than overt diabetes on pregnancy outcome.

Results

Fasting, 1-hour, and 2-hour glucose, fasting and 1-hour C-peptide, and HbA1c levels were measured in blood samples obtained from HAPO participants during an oral glucose tolerance test at 24-32 weeks gestation. We tested for association between 458 SNPs mapping to 31 genes in the inflammatory pathway and metabolic phenotypes in 3836 European ancestry and 1713 Thai pregnant women. The strongest evidence for association was observed with TNF alpha and HbA1c (rs1052248; 0.04% increase per allele C; p-value = 4.4×10⁻⁵), RETN and fasting plasma glucose (rs1423096; 0.7 mg/dl decrease per allele A; p-value = 1.1×10⁻⁴), IL8 and 1 hr plasma glucose (rs2886920; 2.6 mg/dl decrease per allele T; p-value = 1.3×10⁻⁴), ADIPOR2 and fasting C-peptide (rs2041139; 0.55 ug/L decrease per allele A; p-value = 1.4×10⁻⁴), LEPR and 1-hour C-peptide (rs1171278; 0.62 ug/L decrease per allele T; p-value = 2.4×10⁻⁴), and IL6 and 1-hour plasma glucose (rs6954897; −2.29 mg/dl decrease per allele G, p-value = 4.3×10⁻⁴).

Conclusions

Based on the genes surveyed in this study the inflammatory pathway is unlikely to have a strong impact on maternal metabolic phenotypes in pregnancy although variation in individual members of the pathway (e.g. RETN, IL8, ADIPOR2, LEPR, IL6, and TNF alpha,) may contribute to metabolic phenotypes in pregnant women.

Genetic and immunological evidence implicates interleukin 6 as a susceptibility gene for leprosy type 2 reaction

In leprosy, type 1 reaction (T1R) and type 2 reaction (T2R) are major causes of nerve injury and permanent disabilities. A previous study on plasma levels of 27 cytokines in patients with T1R or T2R and controls with nonreactional leprosy identified the gene for interleukin 6 (IL-6) as a candidate for genetic analysis. Two nested case-control studies were built from a cohort of 409 patients with leprosy from central Brazil, monitored for T1R and T2R. There was evidence for association between T2R and IL-6 tag single-nucleotide polymorphisms rs2069832 (P = .002), rs2069840 (P = .03), and rs2069845 (P = .04), with information on the entire IL-6 locus, as well as functional IL-6 variant rs1800795 (P = .005). Moreover, IL-6 plasma levels in patients with T2R correlated with IL-6 genotypes (P = .04). No association was found between IL-6 variants and T1R. Identifying genetic predictive factors for leprosy reactions may have a major impact on preventive strategies.

Genetics of adipose tissue biology

Adipose tissue morphology and release of free fatty acids, as well as peptide hormones, are believed to contribute to obesity and related metabolic disorders. These adipose tissue phenotypes are influenced by adiposity, but there is also a strong hereditary impact. Polymorphisms in numerous adipose-expressed genes have been evaluated for association with adipocyte and clinical phenotypes. In our opinion, some results are convincing. Thus ADRB2 and GPR74 genes are associated with adipocyte lipolysis, GPR74 also with BMI; PPARG and SREBP1, which promote adipogenesis and lipid storage, are associated with T2D and possible adiposity; ADIPOQ and ARL15 are associated with circulating levels of adiponectin, ARL15 also with coronary heart disease. We anticipate that the use of complementary approaches such as expression profiling and RNAi screening, and studies of additional levels of gene regulation, that is, miRNA and epigenetics, will be important to unravel the genetics of adipose tissue function.

Genetic variation in proinflammatory cytokines IL6, IL6R, TNF-region, and TNFRSF1A and risk of breast cancer

Proinflammatory cytokines are associated with age-related diseases including arthritis and heart disease. IL6 and TNF also play key roles in estrogen modulation in older women. We explored whether variation in IL6 and TNF genes influenced the risk of breast cancer in samples that differed by age group: <44 years (228 cases and 271 controls), 45-64 years (426 cases and 396 controls), and 65+ years (228 cases and 239 controls). Samples were drawn from population-based case-control studies conducted in Seattle. Age-adjusted odds ratios (ORs) were calculated to evaluate the risk associated with variants in IL6, IL6R, TNF, and TNFRSF1A. There was a significantly increased risk of breast cancer associated with one or more C>T alleles at IL6 rs2069861 among subjects in the oldest age group (OR 1.8, 95% CI 1.1-2.9), but no overall increased risk of breast cancer associated with any IL6 or IL6R variants in the combined data. There were significantly elevated risks of breast cancer among women 45-64 years old associated with a UTR 5' flanking SNP LTA rs2009658 C>G allele (OR 1.5, 95% CI 1.1-1.9) and a nonsynonomous coding SNP TNFRSF1A rs767455 T>C allele (OR 1.3, 95% CI 1.1-1.6); these two variants were also elevated in the combined data (OR 1.3, 95% CI 1.1-1.5 and OR 1.2, 95% CI 1.1-1.4, respectively). This study supports a modest association between a variant in IL6 and breast cancer among older women and TNF-related variants and breast cancer among middle-aged women. Further evaluation of these genes in other studies is warranted.

Gender-specific associations between insulin resistance, hypertension, and markers of inflammation among adult Saudis with and without diabetes mellitus type 2

PURPOSE

In view of the important roles of the pro-inflammatory cytokines tumor necrosis factor alpha (TNF-α), interleukin-6 (IL-6) and the acute phase reactant C-reactive protein (CRP) in glucose metabolism and pathogenesis of diabetes mellitus type 2 (DMT2), we assessed gender-specific differences and relative associations of these inflammatory biomarkers to insulin resistance (IR) and risk markers for DMT2.

MATERIALS AND METHODS

Serum levels of TNF-α, IL-6 and CRP were determined in 119 clinically diagnosed DMT2 cases, 114 non-DMT2 subjects with IR, and 97 age-matched controls. Fasting blood samples were collected and serum glucose levels, lipid profile, and inflammatory markers were analyzed.

RESULTS

In women, a significant association between elevated levels of IL-6 and risk of developing IR [Odds ratio (OR), 4.389, 95 % Confidence Interval (CI) 1.6-11.52, p = 0.004] was found. Significant associations were also found between elevated levels of CRP and risk of hypertension only in female subjects [OR (95% CI) 2.153 (1.04-4.53), p = 0.046]. While, in male subjects, a significant association between elevated levels of TNF-α and risk of developing IR [OR (95% CI) 2.32 (1.09-4.93), p = 0.029] was found.

CONCLUSION

The present study showed apparent gender differences in the association of IL-6, CRP, and TNF-a with risks of IR and hypertension, and this could be attributed to sexual dimorphism in fat distribution.

Common variations in the genes encoding C-reactive protein, tumor necrosis factor-alpha, and interleukin-6, and the risk of clinical diabetes in the Women's Health Initiative Observational Study

BACKGROUND

Circulating concentrations of high-sensitivity C-reactive protein (CRP), tumor necrosis factor-α (TNF-α), and interleukin-6 (IL-6) have been associated with an increased risk of diabetes.

METHODS

To examine the roles of genetic variation in the genes encoding CRP, TNF- α, and IL-6 in the development of diabetes, we conducted a prospective case-control study nested within the Women's Health Initiative Observational Study. We followed 82 069 postmenopausal women (50-79 years of age) with no history of diabetes for incident diabetes for a mean follow-up of 5.5 years. We identified 1584 cases and matched them with 2198 controls with respect to age, ethnicity, clinical center, time of blood draw, and length of follow-up. We genotyped 13 haplotype-tagging single-nucleotide polymorphisms (tSNPs) across 2.3 kb of the CRP (C-reactive protein, pentraxin-related) gene, 16 tSNPs across 2.8 kb of the TNF (tumor necrosis factor) gene, and 14 tSNPs across 4.8 kb of the IL6 [interleukin 6 (interferon, beta 2)] gene. Plasma concentrations of TNF-α receptor 2 (TNF-α-R2) and IL-6 were measured.

RESULTS

After adjusting for matching factors, confounding variables, and multiple comparisons, we found 8 variants in the TNF gene to be associated with plasma TNF-α-R2 concentrations in white women (q < 0.05). After adjusting for multiple comparisons (q > 0.05), we found no association of any IL6 gene variant with plasma IL-6 concentration, nor did we find any significant associations between any SNPs among these 3 genes and diabetes risk (q > 0.05).

CONCLUSIONS

We found modest associations between TNF variants and circulating concentrations of TNF-α-R2. Common variants of the CRP, TNF, and IL6 genes were not significantly associated with risk of clinical diabetes in postmenopausal women.

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.

Genetic risk factors for post-infectious irritable bowel syndrome following a waterborne outbreak of gastroenteritis

BACKGROUND & AIMS

Acute gastroenteritis is the strongest risk factor for irritable bowel syndrome (IBS). In May 2000, >2300 residents of Walkerton, Ontario, developed gastroenteritis from microbial contamination of the municipal water supply; a longitudinal study found that >36.2% of these developed IBS. We used this cohort to study genetic susceptibility to post-infectious (PI)-IBS.

METHODS

We screened 79 functional variants of genes with products involved in serotoninergic pathways, intestinal epithelial barrier function, and innate immunity and performed fine mapping in regions of interest. We compared data from Walkerton residents who developed gastroenteritis and reported PI-IBS 2 to 3 years after the outbreak (n = 228, cases) with data from residents who developed gastroenteritis but did not develop PI-IBS (n = 581, controls).

RESULTS

Four variants were associated with PI-IBS, although the association was not significant after correction for the total number of single nucleotide polymorphisms. Two were located in TLR9, which encodes a pattern recognition receptor (rs352139, P545P; P = .0059 and rs5743836, -T1237C; P = .0250; r(2) < 0.14); 1 was in CDH1, which encodes a tight junction protein (rs16260, -C160A; P = .0352); and 1 was in IL6, which encodes a cytokine (rs1800795, -G174C; P = .0420). Denser mapping of these 3 regions revealed 1 novel association in IL6 (rs2069861; P = .0069) and 14 associations that could be accounted for by linkage disequilibrium with the 4 original variants. The TLR9, IL6, and CDH1 variants all persisted as independent risk factors for PI-IBS when controlling for previously identified clinical risk factors.

CONCLUSION

This is the first descriptive study to assess potential genetic determinants of PI-IBS. Genes that encode proteins involved in epithelial cell barrier function and the innate immune response to enteric bacteria are associated with development of IBS following acute gastroenteritis.

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.

Chromosome 7p linkage and association study for diabetes related traits and type 2 diabetes in an African-American population enriched for nephropathy

BACKGROUND

Previously we performed a linkage scan of 638 African American affected sibling pairs (ASP) with type 2 diabetes (T2D) enriched for end-stage renal disease (ESRD). Ordered subset linkage analysis (OSA) revealed a linkage peak on chromosome 7p in the subset of families with earlier age of T2D diagnosis.

METHODS

We fine mapped this region by genotyping 11 additional polymorphic markers in the same ASP and investigated a total of 68 single nucleotide polymorphisms (SNPs) in functional candidate genes (GCK1, IL6, IGFBP1 and IGFBP3) for association with age of T2D diagnosis, age of ESRD diagnosis, duration of T2D to onset of ESRD, body mass index (BMI) in African American cases and T2D-ESRD in an African American case-control cohort. OSA of fine mapping markers supported linkage at 28 cM on 7p (near D7S3051) in early-onset T2D families (max. LOD = 3.61, P = 0.002). SNPs in candidate genes and 70 ancestry-informative markers (AIMs) were evaluated in 577 African American T2D-ESRD cases and 596 African American controls.

RESULTS

The most significant association was observed between ESRD age of diagnosis and SNP rs730497, located in intron 1 of the GCK1 gene (recessive T2D age-adjusted P = 0.0006). Nominal associations were observed with GCK1 SNPs and T2D age of diagnosis (BMI-adjusted P = 0.014 to 0.032). Also, one IGFBP1 and four IGFBP3 SNPs showed nominal genotypic association with T2D-ESRD (P = 0.002-0.049). After correcting for multiple tests, only rs730497 remanined significant.

CONCLUSION

Variant rs730947 in the GCK1 gene appears to play a role in early ESRD onset in African Americans.

Convergence of hormones, inflammation, and energy-related factors: a novel pathway of cancer etiology

Colorectal cancer (CRC) is a multifactorial disease with several hypothesized etiologic factors including inflammatory processes; hormones such as estrogen, androgen, and insulin; and energy-related factors. We present evidence that integrates these elements in a pathway we call the convergence of hormones, inflammation, and energy-related factors (CHIEF). First, given the physiology of the gut, substantial epidemiologic and molecular data support the hypothesis that activation of innate immunity in the normal gut mucosa by various environmental agents (commensal bacteria, dietary antigens, mucosal irritants, pathogens) and endogenous factors such as estrogen, androgens, and insulin levels provokes basal inflammation as an underlying factor of the association of insulin, estrogen, and energy-related factors with CRC. Second, critical genes involved in this pathway, e.g., phosphatase tensin homologue on chromosome 10 (PTEN) and serine threonine kinase 11 (STK11)/LKB1, are tumor suppressor genes often mutated in intestinal cancer or CRC. Third, laboratory experiments show that cellular PTEN and STK11/LKB1 tumor suppressor enzymes are vulnerable to inactivation by redox-active species, especially chemically reactive lipid mediators of inflammation and redox stress. Epidemiologic data further support the underlying proposal that CHIEF comprises important elements of CRC risk. Although this discussion of the CHIEF pathway focuses on CRC, we believe that this pathway may play an important role in the etiology of other cancers as well.

Genetic predisposition, Western dietary pattern, and the risk of type 2 diabetes in men

BACKGROUND

A widely held hypothesis is that interactions between genetic predisposition and Western-type lifestyle contribute to the epidemic of type 2 diabetes (T2D). No study has tested this hypothesis.

OBJECTIVE

The objective was to assess whether established genetic variants, mainly from genomewide association studies, modify dietary patterns in predicting diabetes risk.

DESIGN

We determined 10 polymorphisms in a prospective, nested, case-control study of 1196 diabetic and 1337 nondiabetic men. A genetic risk score (GRS) was generated by using an allele counting method. Baseline dietary intakes were collected by using a semiquantitative food-frequency questionnaire. We used factor analysis to derive Western and "Prudent" dietary patterns from 40 food groups.

RESULTS

A significant interaction (P = 0.02) was observed between the GRS and Western dietary pattern. The multivariable odds ratios (ORs) of T2D across increasing quartiles for the Western dietary pattern were 1.00, 1.23 (95% CI: 0.88, 1.73), 1.49 (1.06,2.09), and 2.06 (1.48, 2.88) among men with a high GRS (>/=12 risk alleles; P for trend = 0.01). The Western dietary pattern was not associated with diabetes risk among those with a lower GRS. In addition, we found that intakes of processed meat, red meat, and heme iron, which characterized the Western dietary pattern, showed significant interactions with GRS in relation to diabetes risk (P for interaction = 0.029, 0.02, and 0.0004, respectively). The diet-diabetes associations were more evident among men with a high GRS (>/=12) than in those with a low GRS.

CONCLUSION

Genetic predisposition may synergistically interact with a Western dietary pattern in determining diabetes risk in men.