Association of Immune and Metabolic ReceptorsC5aRandC5L2with Adiposity in Women

Abstract

Adipose tissue receptorsC5aRandC5L2and their heterodimerization/functionality and interaction with ligandsC5aand acylation stimulating protein (ASP) have been evaluated in cell and rodent studies. Their contribution to obesity factors in humans remains unclear. We hypothesized thatC5areceptors, classically required for host defense, are also associated with adiposity. Anthropometry and fasting blood parameters were measured in 136 women divided by body mass index (BMI): normal/overweight (≤30 kg/m2;n= 34), obese I (≤45 kg/m2;n= 33), obese II (≤51 kg/m2;n= 33), and obese III (≤80 kg/m2;n= 36). Subcutaneous and omental adipose tissueC5aRandC5L2expression were analysed.C5L2expression was comparable between subcutaneous and omental across all BMI groups. Plasma ASP and ASP/omentalC5L2expression increased with BMI (P< 0.001 andP< 0.01, resp.). While plasmaC5awas unchanged,C5aRexpression decreased with increasing BMI in subcutaneous and omental tissues (P< 0.01 andP< 0.05, resp.), with subcutaneous omental depots. OmentalC5L2/C5aRratio increased with BMI (P< 0.01) with correlations betweenC5L2/C5aRand waist circumference, HDL-C, and adiponectin. Tissue and BMI differences in receptors and ligands, particularly in omental, suggest relationship to metabolic disturbances and highlight adipose-immune interactions.