Relationship between serum IL-12 and p40 subunit concentrations and lipid parameters in obese subjects
Agnieszka Nikolajuk, Irina Kowalska, Agnieszka Adamska, Monika Karczewska-Kupczewska, Elzbieta Otziomek, Agnieszka Lebkowska, Maria Gorska & Marek Straczkowski
Numerous studies indicate an association between low-grade chronic inflammation and predisposition to type 2 diabetes and atherosclerosis. IL-12 is a proinflammatory cytokine with proatherogenic properties. IL-12 is a disulfide-linked, 70 kDa (p70) heterodimeric glycoprotein composed of a 40 kDa (p40) subunit and a 35 kDa (p35) subunit. Many data reported higher levels of p40 subunit than total IL-12. The aim of the present study was to estimate serum IL-12 and p40 subunit in lean and obese subjects and to investigate the associations of these parameters with insulin sensitivity and serum lipids. A total 77 women with normal glucose tolerance, 40 with overweight or obesity (BMI>25 kg/m2) and 37 lean were recruited for the present study. Anthropometric measurements, blood biochemical analyses and euglycemic hyperinsulinemic clamp were performed in the studied group. We demonstrated an increase in plasma p40 in obese subjects (P=0.029). We found positive correlations between p40 and fat mass (r=0.24, P=0.04) and significant negative associations with HDL-cholesterol (r=−0.27, P=0.02). Detectable concentrations of plasma IL-12 was observed in 55% subjects. Individuals with detectable serum concentrations of IL-12 had significantly higher levels of serum triglycerides (P=0.049). A significant association between IL-12 and serum total cholesterol (r=0.32, P=0.042) was observed in this subgroup. Our data indicate that IL-12/IL-12p40 system may be associated with lipid abnormalities in obese subjects.