1765-P: Adipose Sirtuin 6 Drives Macrophage Polarization Toward M2 through IL-4 Production and Maintains Systemic Insulin Sensitivity in Mice and Human

Abstract

Adipose tissue inflammation is a reproducible feature of obesity and obesity-linked insulin resistance. Here, using adipocyte-specific Sirt6 knockout mice, we explored whether adipocyte Sirt6 inhibits adipose tissue inflammation and its underlying mechanism. aS6KO mice fed normal chow gained more body weight and fat mass than wild type mice and exhibited glucose intolerance and systemic insulin resistance. Measurement of plasma and tissue cytokines and flow cytometric analysis of adipose stromal vascular cells indicated a decrease in alternatively activated M2 macrophages in adipose tissue of aS6KO mice. Mechanistically, Sirt6 regulated the expression of a canonical type 2 cytokine IL-4 by adipocytes in a cell autonomous manner, which in turn affects M2 macrophage polarization. Consistent with animal experiment data, the degree of obesity and insulin resistance demonstrated by body mass index, fasting blood glucose and HbA1c correlated negatively with the expression of Sirt6 in human visceral fat tissues. Collectively, these results suggest that adipocyte Sirt6 regulates body weight gain and insulin sensitivity independent of diet, and the increased IL-4 production by Sirt6 and resultant M2 polarization of adipose tissue macrophages may attenuate proinflammatory responses in adipose tissue. Disclosure M. Song: None.