Mishra, Shravan K

CD4 + effector T helper 1 (T H 1) cells drive inflammatory bowel disease (IBD). Here, we investigated how integrated signaling, metabolic, and epigenetic programs sustain their pathogenic persistence. We found that enforcing mitochondrial pyruvate metabolism with methyl pyruvate (MePyr) suppressed T H 1 cell effector function and induced the acquisition of a regulatory-like phenotype. MePyr suppressed the activity of glycogen synthase kinase 3β (GSK3β), promoting a metabolic shift from glycolysis toward oxidative phosphorylation (OXPHOS) and limiting the accumulation of intracellular acetyl-CoA. This metabolic reprogramming decreased histone H3 acetylation at genes encoding inflammatory cytokines, thereby decreasing T H 1 cell–associated gene expression. Restoration of inflammatory cytokine production by acetate supplementation or histone deacetylase inhibition established acetyl-CoA–dependent histone acetylation as a mechanistic link between metabolic flux and effector function. Conversely, the cytokine interleukin-21 enhanced T H 1 cell effector activity by promoting a GSK3β-dependent shift from OXPHOS to glycolysis. Single-cell transcriptomic analysis of Crohn’s disease tissue revealed enrichment of glycolytic gene programs in nonregulatory CD4 + T cells. Consistent with these findings, pharmacologic inhibition of GSK3β attenuated disease severity in a T cell–transfer mouse model of colitis. Together, these findings identify a GSK3β-dependent metabolic-epigenetic axis that sustains T H 1 cell pathogenicity and highlight GSK3β as a potential therapeutic target for IBD.

Abstract Background Inflammatory regulatory T cells (Tregs) are one of the hallmarks of therapy resistance. Yet mechanisms leading to inflammatory Treg development and its contribution to inflammatory bowel disease (IBD) are unexplored. Methods Tregs derived from healthy PBMCS were characterized by immune and mitochondrial phenotyping. Transcripts were validated in dataset from IBD intestinal lesions. Wildtype (WT) and IL21 receptor-deleted (Il21r−/−) Tregs were examined in murine models of CD4+ T cell-induced colitis. Results Through in vitro cytokine challenge of Tregs and subsequent analysis, we found that IL21 induces Tregs co-expressing TNF, IFNγ and IL17. Transcriptomic and metabolomic integration revealed upregulation of mRNA and metabolites associated with glycolysis, and amino acid, nucleotide and lipid metabolism. Moreover, IL21-induced metabolic transcripts were more enriched in Treg cluster within scRNA-seq dataset from intestinal lesions of anti-TNF non-responders vs. non-responders. Mechanistically, cell imaging and real-time bioenergetic analysis revealed disruption to mitochondria-ER ultrastructure and function, coinciding with glycogen synthase kinase 3β (GSK3β) activation and glycolytic switch rather than pyruvate-mediated oxidative phosphorylation. GSK3β inhibition or methyl pyruvate supplementation rescued IL21-induced metabolic and inflammatory phenotypes. In contrast to WT Tregs, murine Il21r−/− Treg transfer efficiently prevented and rescued CD4+CD45Rbhigh T cell-induced colitis. Conclusions IL21-induced metabolic dysfunction can incapacitate Treg immunosuppressive function. Desensitizing Tregs to IL21 through various therapeutic approaches can alleviate IBD. This work was supported by National Institute of Diabetes and Digestive and Kidney Diseases (NIDDK) K01DK124358, the Pilot & Feasibility Award by the Center for Cell Signaling in Gastroenterology (P30DK084567), and the Mayo Clinic Center for Biomedical Discovery Career Development Award, and David F. and Margaret T. Grohne Cancer Immunology and Immunotherapy (to AOB).