Biological variations, genetic polymorphisms and familial resemblance of TNF-alpha and IL-6 concentrations: STANISLAS cohort

Cytokines are involved in the development of several inflammatory diseases and atherosclerosis. Their variations in healthy individuals are not well defined. The aims of this study were: firstly, to identify factors affecting biological variation of interleukin-6 (IL-6) and tumour necrosis factor-alpha (TNF-alpha); secondly, to study their family resemblance; and thirdly, to evaluate the effect of two TNF-alpha (-308G/A and -238G/A) and two IL-6 polymorphisms (174G/C and -572G/C) on their corresponding circulating levels. A total of 171 healthy families selected from the STANISLAS cohort were studied. Age was negatively related to TNF-alpha concentrations in offspring only (both sons and daughters). Additionally, IL-6 and TNF-alpha levels were differently influenced by gender, white blood cells, tobacco consumption, and HDL-cholesterol level. A weak significant familial resemblance for TNF-alpha concentration was observed in siblings only. There was no significant familial resemblance for IL-6 levels. The TNF-alpha -308A allele was associated with decreased TNF-alpha alpha concentrations in both offspring aged less than 18 and males without overweight (BMI<25 kg/m(2)). Fathers carrying the IL-6 -174CC genotype had higher IL-6 levels than those with the IL-6 -174G allele. Parents with the IL-6 -572GG genotype had higher IL-6 concentrations than the C allele carriers. In this sample of healthy families, plasma levels of IL-6 and TNF-alpha were differently affected by biological parameters including age, gender and smoking, and the impact of their respective polymorphisms was influenced by gender, age and BMI.