Post-Doctoral Fellow Henry Ford Health DETROIT, Michigan, United States
Disclosure(s):
Mohammad Nematullah, PhD: No financial relationships to disclose
Introduction/Rationale: CD4⁺ Th17 cells are central drivers of multiple sclerosis (MS) pathology, yet mechanisms regulating their differentiation and effector functions is not fully understood. We recently discovered that Immune-Responsive Gene 1 (Irg1), a mitochondrial enzyme previously characterized in myeloid cells, is expressed in CD4⁺ T cells during experimental autoimmune encephalomyelitis (EAE).
Methods: Our published studies showed that global Irg1 knockout (Irg1KO) mice develop more severe EAE with expansion of pathogenic IL-17A⁺GM-CSF⁺IFN-γ⁺ CD4⁺ T cells. scRNA-seq analysis revealed enrichment of Th17 differentiation, IL-17 signaling, TCR, NF-κB, and cytokine–cytokine interaction pathways, consistent with heightened Th17 pathogenicity. qPCR confirmed elevated Il17a, Ifng, and Csf2 expression in Irg1 KO CD4⁺ T cells. Adoptive transfer of Irg1 KO CD4⁺ T cells induced severe EAE, confirming a cell-intrinsic pathogenic program. To directly test this, we generated an inducible CD4⁺ T cell-specific conditional Irg1 knockout mouse model.
Results: The conditional Irg1 knockout mouse model exhibited earlier onset and higher disease severity. Flow cytometry revealed robust CNS infiltration of triple-positive Th17 cells (IL-17A⁺GM-CSF⁺IFN-γ⁺), further supporting an intrinsic regulatory role of Irg1 in CD4⁺ T cells. Single cell RNA-seq revealed upregulation of Stat3, Irf4, and Batf in Irg1-deficient CD4⁺ T cells, suggesting activation of a proinflammatory Th17 transcriptional network. Ongoing studies demonstrate that Irg1 modulates chromatin accessibility and histone modifications at Th17-associated loci, implicating epigenetic control as a mechanism of regulation.
Conclusion: Collectively, our findings identify Irg1 as a critical metabolic-epigenetic checkpoint that restrains Th17-driven neuroinflammation and represents a promising therapeutic target for MS.
