Sex differences in inflammatory markers: what is the contribution of visceral adiposity?

C-reactive protein (CRP) concentrations have been found to be higher in premenopausal women than in men, whereas interleukin-6 (IL-6) and tumor necrosis factor-alpha (TNF-alpha) concentrations have been reported to be lower in women than in men.

The objective was to determine whether the sex difference in body fat distribution accounts for the observed sex differences in inflammatory markers.

Plasma CRP, IL-6, and TNF-alpha concentrations were measured in 208 healthy men (age: 42.2 +/- 15.2 y) and in 145 healthy women (age: 36.8 +/- 11.1 y).

Compared with men, premenopausal women had higher CRP concentrations [1.24 (25th percentile: 0.54; 75th percentile: 3.04) compared with 0.94 (0.51, 2.40) mg/L; P < 0.05] and lower plasma TNF-alpha concentrations [1.50 (25th percentile: 1.23; 75th percentile: 1.82) compared with 1.71 (1.40, 2.05) pg/mL; P < 0.001]. No sex difference in IL-6 concentrations was noted. Regression analyses indicated that the relation between CRP or IL-6 and visceral adipose tissue (VAT) and subcutaneous AT (SAT) was sex-specific; a significantly steeper slope was observed in women than in men (P < 0.05). Sex differences in CRP concentrations were abolished after SAT was adjusted for. In a multivariate model of the whole sample, we found that both SAT and VAT and the sex x SAT interaction term were significant correlates of CRP and IL-6 concentrations. Finally, whereas CRP concentrations were largely influenced by visceral adiposity in men, subcutaneous adiposity was the key correlate of CRP in women.

The higher CRP concentrations found in women appear to be due to their greater accumulation of subcutaneous fat than that observed in men.