Genetic- and diet-induced
obesity and
insulin resistance are associated with an increase in mechanistic target of
rapamycin complex (mTORC) 1 activity in adipose tissue. We investigated herein the effects of pharmacological
mTORC1 inhibition in the development of adipose tissue
inflammation induced by high-fat diet (HFD) feeding, as well as in the polarization, metabolism and function of bone marrow-derived macrophages (BMDM). For this, C57BL/6J mice fed with a standard chow diet or a HFD (60% of calories from fat) and treated with either vehicle (0.1% Me2SO, 0.2%
methylcellulose) or
rapamycin (2mg/kg/ day, gavage) during 30days were evaluated for
body weight, adiposity,
glucose tolerance and adipose tissue
inflammation. Although
rapamycin did not affect the increase in
body weight and adiposity, it exacerbated the
glucose intolerance and adipose tissue
inflammation induced by HFD feeding, as evidenced by the increased adipose tissue percentage of M1 macrophages, naive and activated cytotoxic T lymphocytes, and
mRNA levels of proinflammatory molecules, such as TNF-α,
IL-6 and MCP-1. In BMDM in vitro, pharmacological
mTORC1 inhibition induced phosphorylation of NFκB p65 and spontaneous polarization of macrophages to a proinflammatory M1 profile, while it impaired M2 polarization induced by IL-4+IL-13, glycolysis and phagocytosis. Altogether, these findings indicate that
mTORC1 activity is an important determinant of adipose tissue inflammatory profile and macrophage plasticity, metabolism and function.