IL6 and IL1B Polymorphisms are Associated With Fat Mass in Older Men: The MrOS Study Sweden

Abstract

There is growing evidence that immune functions are linked to the regulation of body fat. Our studies of knockout mice indicate that both endogenous interleukin (IL)-6 and IL-1 can suppress mature-onset obesity. We now investigated whether four common polymorphisms of the IL6 and IL1 systems are associated with the fat mass measured with dual-energy X-ray absorptiometry (DXA) in elderly men (n = 3,014). The study subjects were from the Swedish part of the MrOS multicenter population study and 69-81 years of age. The IL6 -174 G>C (Minor allele frequency (MAF) = 48%) gene promoter polymorphism was associated with the primary outcome total fat mass (P = 0.006) and regional fat masses, but not with lean body mass. The IL1B -31T>C (MAF = 34%) polymorphism was also associated with total fat (P = 0.007) and regional fat masses, but not lean body mass. The IL-1 receptor antagonist (IL-1ra) gene (IL1RN) +2018 T>C (MAF = 27%) polymorphism (in linkage disequilibrium (LD) with a well-studied variable number tandem repeat of 86 base pair (bp)) and IL1B +3953 C>T (MAF = 26%) polymorphism were not associated with total fat mass. In conclusion, the IL-1 and IL-6 systems, shown to suppress mature-onset obesity in experimental animals, contain gene polymorphisms that are associated with fat, but not lean, mass in elderly men.