The mechanism of macrophage glycolysis regulating Th17 cell differentiation and promoting the progression of EAN mice.

This study investigates how macrophage glycolysis interacts with CD4+ T cells to drive experimental autoimmune neuritis (EAN) progression. In EAN mice, expression of key glycolytic genes (LDHA, GLUT1, HK2, and PKM2) was gradually upregulated in splenic macrophages and sciatic nerve. By the disease peak (day 18 p.i.), these genes reaching approximately 4-to-8-fold increase over controls, paralleling a continuous expansion of the splenic M1 macrophage population. Crucially, in vivo glycolysis inhibition via 2-deoxyglucose (2-DG) effectively suppressed splenic M1 polarization and sciatic nerve CD86 IHC intensity, thereby mitigating EAN clinical scores from day 10 onward. Further in vitro experiments revealed that M1-polarized macrophages exhibited significantly enhanced glycolytic activity, characterized by increased glucose uptake, ATP generation, and lactate secretion. Their conditioned medium successfully drove CD4+ T cell differentiation into the Th17 subset, upregulating RORγt expression and the secretion of IL-17 and IL-22. Mechanistically, extracellular lactate promoted Th17 differentiation by facilitating PKM2 nuclear translocation, which enhanced STAT3 phosphorylation and RORγt expression while reciprocally suppressing Foxp3. Genetically overexpressing PKM2 augmented lactate-induced Th17 cytokine secretion, whereas pharmacological stabilization of PKM2 tetramers via TEPP-46 blocked its nuclear entry and reduced Th17 differentiation. Ultimately, targeted in vivo intervention with TEPP-46 significantly improved neurological function scores in EAN mice, accompanied by diminished Th17 cell infiltration and alleviated inflammatory demyelination. Together, our findings elucidate the "macrophage glycolysis-lactate-PKM2" axis in regulating Th17 differentiation, offering a novel metabolic-immune therapeutic strategy for EAN and its clinical counterpart, acute inflammatory demyelinating polyneuropathy (AIDP).