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

Diabetes and smoking are more important for prognosis of patients with peripheral arterial disease than some genetic polymorphisms

Background: The role of genetic polymorphisms in peripheral arterial disease (PAD) is incompletely understood. We tested whether selected single nucleotide polymorphisms (SNPs) were associated with PAD and with adverse events in an observational study cohort. Also, the role of diabetes and smoking was studied. Patients and methods: 742 patients with PAD and 713 age- and gender-matched control subjects were subjected to yearly physical and laboratory investigations and were managed for 5 years according to the European guidelines on cardiovascular disease prevention. The occurrence of all-cause death, cardiovascular death, non-fatal myocardial infarction, ischemic stroke or critical limb ischemia (major events) and revascularization procedures (minor events) was recorded. In 655 patients with PAD and 612 control subjects the following SNPs were determined: rs1466408, rs13428968 and rs12803 of NR4A2 gene, rs10499563 of IL6 gene, rs668 and rs12953 of PECAM1 gene, and rs10861032 of Chr12 locus. Results: The distribution of selected SNPs did not differ between patients with PAD and control subjects, and neither between subjects with or without major adverse events. In contrast, diabetes and smoking affected survival and event-free survival. Among patients with PAD, diabetes doubled the hazard ratio (HR) for cardiovascular death and smoking doubled the HR for death or major event. The 5-year survival of diabetics with PAD was 0.80 (CI 0.75-0.85) and of non-diabetics with PAD 0.87 (CI 0.84-0.90), p = 0.045. The 5-year survival of active smokers with PA D was 0.80 (CI 0.75-0.62), of former smokers 0.83 (CI 0.79-0.88), and of never-smokers 0.89 (CI 0.86-0.93), p = 0.024. Conclusions: SNPs of NR4A2, IL6, PECAM1 and Chr12 were not associated with PAD or with major adverse events. However, diabetes and smoking were associated with worse survival and event-free survival in patients with PAD.

CRP-level-associated polymorphism rs1205 within the CRP gene is associated with 2-hour glucose level: The SAPPHIRe study

C-reactive protein (CRP) encoded by CRP gene is a reflection of systemic inflammation. Many studies associated CRP level with diabetes and glucose levels, but the association of CRP gene with these traits is unclear. We conducted a cross-sectional study consisting of 945 siblings from 330 families collected by the Stanford Asian Pacific Program in Hypertension and Insulin Resistance (SAPPHIRe) to investigate associations between CRP polymorphisms, circulating CRP, diabetes, and glucose levels. Five single-nucleotide polymorphisms were analyzed: rs3093059, rs2794521, rs1417938, rs1800947, and rs1205. The generalized estimating equation approach was used to deal with correlated data within families. CRP level was positively correlated with diabetes prevalence and levels of fasting and 2-hour glucose (each P < 0.008). Alleles C at rs3093059 and G at rs1205 were associated with elevated CRP level (each P < 1.2 × 10⁻⁶). Allele C at rs3093059 was associated with fasting glucose (β = 0.20, P = 0.045) and G at rs1205 was associated with 2-hour glucose (β = 0.46, P = 0.00090) post oral glucose tolerance test, but only the latter passed Bonferroni correction. No polymorphism was associated with diabetes. Since 2-hour glucose is an indicator of glucose tolerance, this study indicated CRP gene is associated with glucose intolerance.

Associations of TNF-α and IL-6 polymorphisms with osteoporosis through joint effects and interactions with LEPR gene in Taiwan: Taichung Community Health Study for Elders (TCHS-E)

Osteoporosis (OST) is a complex multifactorial disease considered to result from interactions of multiple gene and environmental factors. Tumor necrosis factor (TNF)-α and interleukin (IL)-6 are pleiotropic cytokines essential for bone remodeling; and hormone leptin has immunomodulatory effects that stimulate the synthesis of IL-6 and TNF-α. Leptin is involved in the modulation of bone growth and turnover; and its actions are bound by leptin receptor (LEPR). Prior studies evaluated the effects of TNF-α, IL-6, and LEPR gene polymorphisms separately on bone mineral densities (BMD) or OST. In this study, we assessed the roles of TNF-α and IL-6 gene polymorphisms in OST through joint effects and interactions with LEPR gene. We also evaluated possible joint effects and interactions between these polymorphisms and physical activity. Ten tag-SNPs (rs1799964, rs1800629, rs3093662 in TNF-α; rs1880243, rs1800796, rs1554606 in IL-6; and rs1751492, rs8179183, rs1805096, rs1892534 in LEPR) were used to genotype 103 OST cases and 369 controls. BMD of lumbar spine (LS), femoral neck (FN), and total hip (TH) were measured by dual-energy X-ray absorptiometry. Our data showed that TNF-α and IL-6 polymorphisms were associated with overall and site-specific OST in both sexes, and that these associations were dependent on rs1805096 and rs1892534 genotypes of LEPR. In men, LEPR A-G-G-G haplotype was associated with FN OST (OR 4.65, 95 % CI 1.61-13.40, p = 0.004). Genotype AA/AG of LEPR rs1751492 was associated with overall and FN OST in women without physical activity, but not in women with physical activity (p < 0.05 for interaction between physical activity and LEPR rs1751492). In men, we detected significant interactions of IL-6 rs1800796 with LEPR rs1805096 and rs1892534 for FN and TH OST (all p < 0.05). Our data indicate that LEPR gene may play joint and interactive roles with TNF-α and IL-6 genes and physical inactivity in development of OST. Haplotype analyses revealed that the correlations tended to be prominent in men with FN OST.

Comparison of Serum Adipocytokine Levels according to Metabolic Health and Obesity Status

BACKGROUND

Metabolic health is an emerging concept that is highly correlated with various metabolic complications, and adipocytokines have been causally linked to a wide range of metabolic diseases. Thus, this study compared serum adipocytokine levels according to metabolic health and obesity status.

METHODS

Four hundred and fifty-six nondiabetic subjects (mean age, 40.5 years) were categorized into four groups according to metabolic health and obesity status: metabolically healthy nonobese (MHNO), metabolically healthy obese (MHO), metabolically unhealthy nonobese (MUHNO), and metabolically unhealthy obese (MUHO). Being metabolically healthy was defined as the presence of fewer than two of the following five metabolic abnormalities: high blood pressure, high fasting blood glucose, high triglyceride, low high density lipoprotein cholesterol, and being in the highest decile of the homeostatic model assessment of insulin resistance index. Obesity status was assessed using body mass index (BMI), with obesity defined as a BMI higher than 25 kg/m². Levels of serum interleukin-6 (IL-6), monocyte chemoattractant protein-1 (MCP-1), tumor necrosis factor α (TNF-α), and adipocyte fatty acid binding protein (A-FABP) were also evaluated.

RESULTS

Of the 456 subjects, 247 (54.2%) were in the MHNO group, 66 (14.5%) were in the MHO group, 66 (14.5%) were in the MUHNO group, and 77 (16.9%) were in the MUHO group. There were no significant differences in IL-6 or MCP-1 levels among the groups, but levels of TNF-α and A-FABP were significantly higher in the MUHNO group compared to the MHNO group.

CONCLUSION

High TNF-α and A-FABP levels are significantly associated with metabolically unhealthiness in nonobese Korean individuals.

A Bayesian approach for instrumental variable analysis with censored time-to-event outcome

Instrumental variable (IV) analysis has been widely used in economics, epidemiology, and other fields to estimate the causal effects of covariates on outcomes, in the presence of unobserved confounders and/or measurement errors in covariates. However, IV methods for time-to-event outcome with censored data remain underdeveloped. This paper proposes a Bayesian approach for IV analysis with censored time-to-event outcome by using a two-stage linear model. A Markov chain Monte Carlo sampling method is developed for parameter estimation for both normal and non-normal linear models with elliptically contoured error distributions. The performance of our method is examined by simulation studies. Our method largely reduces bias and greatly improves coverage probability of the estimated causal effect, compared with the method that ignores the unobserved confounders and measurement errors. We illustrate our method on the Women's Health Initiative Observational Study and the Atherosclerosis Risk in Communities Study.

Modifying effect of a common polymorphism in the interleukin-6 promoter on the relationship between long-term exposure to traffic-related particulate matter and heart rate variability

Background

Exposure to particulate matter (PM) has been associated with an increase in many inflammatory markers, including interleukin 6 (IL6). Air pollution exposure has also been suggested to induce an imbalance in the autonomic nervous system (ANS), such as a decrease in heart rate variability (HRV). In this study we aimed to investigate the modifying effect of polymorphisms in a major proinflammatory marker gene, interleukin 6 (IL6), on the relationship between long-term exposure to traffic-related PM₁₀ (TPM₁₀) and HRV.

Methods

For this cross-sectional study we analysed 1552 participants of the SAPALDIA cohort aged 50 years and older. Included were persons with valid genotype data, who underwent ambulatory 24-hr electrocardiogram monitoring, and reported on medical history and lifestyle. Main effects of annual average TPM₁₀ and IL6 gene variants (rs1800795; rs2069827; rs2069840; rs10242595) on HRV indices and their interaction with average annual exposure to TPM₁₀ were tested, applying a multivariable mixed linear model.

Results

No overall association of TPM₁₀ on HRV was found. Carriers of two proinflammatory G-alleles of the functional IL6 -174 G/C (rs1800795) polymorphism exhibited lower HRV. An inverse association between a 1 µg/m³ increment in yearly averaged TPM₁₀ and HRV was restricted to GG genotypes at this locus with a standard deviation of normal-to-normal intervals (SDNN) (GG-carriers: −1.8%; 95% confidence interval −3.5 to 0.01; p_{interaction(additive)} = 0.028); and low frequency power (LF) (GG-carriers: −5.7%; 95%CI: −10.4 to −0.8; p_{interaction(dominant)} = 0.049).

Conclusions

Our results are consistent with the hypothesis that traffic-related air pollution decreases heart rate variability through inflammatory mechanisms.

Interleukin-6 gene polymorphisms, dietary fat intake, obesity and serum lipid concentrations in black and white South African women

This study investigated interactions between dietary fat intake and IL-6 polymorphisms on obesity and serum lipids in black and white South African (SA) women. Normal-weight and obese, black and white women underwent measurements of body composition, serum lipids and dietary fat intake, and were genotyped for the IL-6 -174 G>C, IVS3 +281 G>T and IVS4 +869 A>G polymorphisms. In black women the IVS4 +869 G allele was associated with greater adiposity, and with increasing dietary fat intake adiposity increased in the IVS3 +281 GT+GG and IVS4 +869 AA or AG genotypes. In white women, with increasing omega-3 (n-3) intake and decreasing n-6:n-3 ratio, body mass index (BMI) decreased in those with the -174 C allele, IVS3 +281 T allele and IVS4 +869 AG genotype. In the white women, those with the IVS3 +281 T allele had lower triglycerides. Further, with increasing n-3 polyunsaturated fatty acid (PUFA); triglyceride and total cholesterol:high-density lipoprotein cholesterol (T-C:HDL-C) ratio decreased in those with the -174 C allele. In black women, with increasing total fat intake, triglycerides and T-C:HDL-C ratio increased in those with the IVS4 +869 G allele. This study is the first to show that dietary fat intake modulates the relationship between the IL-6 -174 G>C, IVS3 +281 G>T and IVS4 +869 A>G polymorphisms on obesity and serum lipids in black and white SA women.

Association of CRP gene polymorphisms with serum CRP level and handgrip strength in community-dwelling elders in Taiwan: Taichung Community Health Study for Elders (TCHS-E)

Low handgrip strength is one component of frailty, characterized by loss of reserves, including energy, physical ability, cognition and health. This study rated the effect of five single-nucleotide polymorphisms (SNPs) in C-reactive protein (CRP) gene on the serum CRP level and handgrip strength in elderly Taiwanese. Five SNPs (rs2794520, rs1205, rs1130864, rs1800947, and rs3093059) of CRP gene were utilized to genotype 472 unrelated elderly subjects (mean age 73.8years). Handgrip strength was measured by handgrip dynamometer (TTM Dynamometer, Tsutsumi, Tokyo). Our study demonstrated that minor alleles of rs2794520 and rs1205 were C, whereas they were T in most ethnic groups. There exist significant associations of three CRP polymorphisms (rs2794520, rs1205 and rs3093059) with serum CRP level and handgrip strength. All three had simultaneous influence on raising CRP levels and reducing handgrip strength. Genotype and sex interactions emerged for rs2794520 and rs1205 in relation to CRP levels (p<0.05). In addition, haplotype C-C-C-C-C was associated with higher levels of CRP (exp(β)=1.45; p<0.001) and lower handgrip strength (β=-1.00kg, p<0.05). We conclude that SNPs rs2794520, rs1205, and rs3093059 of CRP gene, as well as haplotype C-C-C-C-C may be important biomarkers for susceptibility to low handgrip strength and high serum CRP level in elders; further studies are required.

Genetic polymorphism of tumor necrosis factor promoter region and susceptibility to develop Hodgkin lymphoma in a Mexican population

Hodgkin lymphoma (HL) is a rare neoplasm of the lymphatic system, in which inflammation and allelic variants in cytokines have been proposed as etiological factors. Epstein-Barr virus infection is often associated as a risk factor in HL and since cytokines are involved in the humoral response to viral infection. Our aim was to study the association between single nucleotide polymorphisms (SNPs) located in the tumor necrosis factor (TNF) gene (- 376G> A, - 238G> A and 581G> A) in a sample of Mexican patients (56 cases) and their susceptibility to develop HL, comparing these SNPs among healthy individuals (127 controls). Frequencies for TNF - 238G> A and TNF 581G> A showed no significant differences between cases and controls. However, the proportion of cases with the GA genotype of - 376 SNP showed a significant difference as compared to controls, odds ratio = 4.41 (95% confidence interval: 1.21-16.6), p = 0.02. We found that in this group of patients from Mexico the SNP - 376G> A in TNF shows an association with higher risk for HL.

The association of baseline adipocytokine levels with glycemic progression in nondiabetic Korean adults in 4 years of follow-up

AIMS

Low-grade inflammation and lipotoxicity contribute to insulin resistance and islet secretory dysfunction that lead to insulin deficiency. We analyzed the associations of several adipocytokines measured at baseline with glycemic progression in non-diabetic Korean subjects after a 4-year follow-up.

METHODS

In 479 non-diabetic Korean subjects who underwent medical screening in 2003, serum tumor necrosis factor (TNF)-α, interleukin (IL)-6, retinol-binding protein (RBP)-4, monocyte chemoattractant protein (MCP)-1, visfatin and fatty acid-binding protein (FABP)-4 were measured at baseline. After 4 years, changes in glycemia were assessed.

RESULTS

Among the subjects, 79.2% maintained their baseline glycemic status, 14.6% progressed to worse glycemic status (impaired fasting glucose (IFG) to diabetes, normoglycemia to IFG or normoglycemia to diabetes) and 5.8% regressed to normoglycemia after 4 years. Baseline TNF-α and FABP4 showed the highest values in the progression group. In the logistic regression analyses with glycemic progression as the dependent variable and TNF-α and FABP4 as independent variables in separate models, TNF-α and FABP4 individually predicted glycemic progression after adjustment for confounding variables. When both adipocytokines were included in the same model, only FABP4 significantly predicted glycemic progression after 4 years.

CONCLUSIONS

TNF-α and FABP4 were significant predictors for glycemic progression in 4 years, with FABP4 being the stronger predictor.