Increased levels of calprotectin in obesity are related to macrophage content. Impact on inflammation and effect of weight loss

Calprotectin has been recently described as a novel marker of obesity.

The aim was to determine the circulating concentrations and expression levels of calprotectin subunits (S100A8 and S100A9) in VAT exploring its impact on insulin resistance and inflammation and the effect of weight loss.

We included 53 subjects in the study. Gene expression levels of S100A8/A9 complex were analyzed in VAT as well as in both adipocytes and SVFC.

In addition, circulating calprotectin and sRAGE concentrations were measured before and after weight loss achieved by Roux-en-Y gastric bypass (RYGB) (n=26). Circulating concentrations and VAT expression of S100A8/A9 complex were increased in normoglycemic and type 2 diabetic obese patients (P<0.01) and associated with markers of inflammation (P<0.01). Oppositely, concentrations of sRAGE were significantly lower (P<0.001) in both obese groups compared to lean volunteers. Elevated calprotectin levels in obese patients decreased (P<0.00001) after RYGB while sRAGE concentrations tended to increase. Calprotectin was mainly expressed by SVFC and its expression was significantly correlated (P<0.01) with mRNA levels of the monocyte-macrophage-related molecules CD68, MCP1, CD11B and NOX2. TNF-? treatment significantly enhanced (P<0.05) the mRNA levels of S100A8 of human visceral adipocytes.

The increased levels of calprotectin in obesity and obesity-associated T2D, its positive association with inflammation as well as the higher expression levels in the SVFC in VAT suggests a potential role of this protein as a chemotactic factor in the recruitment of macrophages to VAT increasing inflammation and the development of obesity-associated comorbidities.

CITA DEL ARTÍCULO  Mol Med. 2011 Jul 5. doi: 10.2119/molmed.2011.00144