Suppression of CD4 T cells by Tregs dictates metabolic remodeling of CD8 T cells during effector to memory transition

ABSTRACT Metabolic transitions between naïve, effector and memory T cell states are largely orchestrated by TCR, costimulatory and cytokine signals along with nutrient availability in the immune microenvironment. Treg cells have been shown to play a critical role in the effector-to-memory (E-M) transition of virus-specific CD8 T cells through regulation of proliferation and cytotoxic functional programs. However, the precise Treg-dependent metabolic changes that occur in the microniches and, the underlying molecular and cellular mediators of E-M transition remain undefined. Here we show that Treg cells promote the metabolic remodeling of memory-precursor effector CD8 T cells (MPEC) from aerobic glycolysis to fatty acid oxidation as they enter quiescence after antigen clearance. Our data implicate the anatomic microniche of the splenic white pulp as a site for Treg-MPEC interactions. We further show that optimal E-M metabolic transition requires regulation of effector CD4 T cells and inflammatory myeloid cells through inhibitory CTLA4 signals from Treg cells. Moreover, antagonism of inflammatory cytokine interferon-γ (IFN-γ) signals partially rescues the memory defects associated with absence of Treg cells. Together, these findings support a metabolic triad model of memory CD8 T cell differentiation where Treg-dependent regulation of inflammation from effector CD4 T cells promotes the transition of CD8 T cells from cytotoxic effector to quiescent memory metabolic programs. These studies define novel molecular targets that may be exploited to manipulate metabolism, migration and memory function during vaccination. Full Text Availability The license terms selected by the author(s) for this preprint version do not permit archiving in PMC. The full text is available from the preprint server.