Hyperlipidemia-induced metabolic changes in regulatory T cells result in altered function

Regulatory T cells (Tregs) play a critical role in maintaining self-tolerance and controlling inflammation. However, physiologically relevant conditions that alter Treg function and drive disease pathogenesis are poorly understood and few have been defined. We have previously shown that induction of hyperlipidemia in mice results in changes in Tregs that reduce their function. Here, we set out to examine mechanisms by which hyperlipidemia alters Tregs. Using live-cell metabolic assays, we observed that induction of hyperlipidemia increases metabolism in Tregs but not conventional T cells. Increased metabolism resulted from preferential activation of the serine/threonine kinase Akt2 (PKB-β). Expression of a constitutively activated form of Akt2 in CD4 T cells was sufficient to increase glycolysis in Tregs and drive changes in Treg subsets. Induction of hyperlipidemia did not alter Treg metabolism in mice lacking Akt2. Activation of Akt2 was sufficient to drive the production of inflammatory cytokines by Tregs. We suggest that hyperlipidemia alters Treg function through effects on metabolism via Akt2 activation thereby promoting plasticity and decreased function of FoxP3+ T cells.