Introduction
When T cells are activated, they upregulate glycolysis and take on a requisite Warburg phenotype. In this study, we evaluated the effect of inhibiting two distinct glycolytic enzymes, GAPDH and PGAM, on CD4 T cell differentiation.
Methods/Results
Using the GAPDH inhibitor heptelidic acid, we found that GAPDH inhibition produces a potent anti-inflammatory phenotype in Th1 cells, significantly reducing IFNγ expression. We further showed that GAPDH inhibition produces the anti-inflammatory metabolite methylglyoxal, which is necessary for its anti-inflammatory effect. GAPDH inhibition also produced anti-inflammatory effects in vivo, as heptelidic acid significantly reduced disease severity and altered immune subsets in a therapeutic treatment paradigm in the MOG35-55 EAE model of multiple sclerosis. Furthermore, we showed that GAPDH inhibition enhances Treg polarization, while inhibiting PGAM, a downstream glycolytic enzyme, potently blocked Treg polarization. Additionally, we found that inhibition of PGAM increases serine biosynthesis and subsequently alters 1-carbon metabolism. We also found that PGAM gene expression is associated with Treg differentiation and response to immunotherapy in lung cancer patients.
Conclusion
Overall, our in vitro and in vivo results indicate that targeting the glycolytic enzyme GAPDH produces an antiinflammatory phenotype via the methylglyoxal pathway, while targeting the downstream enzyme PGAM produces an opposite effect via regulation of serine synthesis. Our findings suggest that the functional consequences of glycolysis inhibition depend on the specific enzymes targeted, which represent promising novel therapeutic targets for immunological disease.
