Intrahepatic fat content correlates with soluble CD163 in relation to weight loss induced by Roux-en-Y gastric bypass.

Objective: Soluble CD163 (sCD163) is a new marker of obesity-related metabolic complications. sCD163 and CD163 mRNA were investigated in relation to the fat distribution at baseline and 12 months after Roux-en-Y gastric bypass (RYGB).

Methods: Thirty-one obese subjects (BMI: 42.3 ± 4.7 kg/m(2)) were enrolled. Subcutaneous (SAT) and visceral adipose tissue (VAT) volume were determined by MRI, intrahepatic lipid content (IHL) by MR-spectroscopy, and body composition by DXA. Fasting blood samples and adipose tissue samples were obtained, and ELISA and RT-PCR were performed.

Results: RYGB-induced weight loss (36 ± 11 kg) was accompanied by a significant reduction in sCD163 (2.1 ± 0.8 mg/l vs. 1.7 ± 0.7 mg/l), SAT, VAT, and IHL (all, P < 0.001). At baseline, sCD163 was associated with VAT (r = 0.40, P < 0.05) but not with SAT or IHL. Moreover, CD163 mRNA was significantly upregulated in VAT compared with SAT at baseline (P < 0.05) and significantly downregulated in SAT after RYGB (P < 0.001). ΔsCD163 was significantly associated with ΔIHL after RYGB compared with baseline (r = 0.40, P < 0.05).

Conclusions: RYGB-induced weight loss results in a reduction of sCD163 and CD163 mRNA. The association between ΔsCD163 and ΔIHL may reflect a reduction in sCD163-producing Kupffer cells in the liver. Moreover, sCD163 may be a marker of "unhealthy" fat distribution in obese subjects.