Cd28 autonomous signaling up-regulates c-myc expression and promotes glycolysis enabling inflammatory t cell responses in multiple sclerosis

Abstract

The immunopathogenesis of multiple sclerosis (MS) depend on the expansion of specific inflammatory T cell subsets, which are key effectors of tissue damage and demyelination. Emerging studies evidence that a reprogramming of T cell metabolism may occur in MS, thus the identification of stimulatory molecules and associated signaling pathways coordinating the metabolic processes that amplify T cell inflammation in MS is pivotal. Here, we characterized the involvement of the cluster of differentiation (CD)28 and associated signaling mediators in the modulation of the metabolic programs regulating proinflammatory T cell functions in relapsing remitting MS (RRMS) patients. We show that CD28 up regulates glycolysis independent of the T cell receptor (TCR) engagement by promoting the increase of c myc and the glucose transporter, Glut1, in RRMS CD4+ T cells. The increase of glycolysis induced by CD28 was important for the expression of inflammatory cytokines related to T helper (Th)17 cells, as demonstrated by the strong inhibition exerted by impairing the glycolytic pathway. Finally, we identified the class 1A phosphatidylinositol 3 kinase (PI3K) as the critical signaling mediator of CD28 that regulates cell metabolism and amplify specific inflammatory T cell phenotypes in MS.