Activation of NLRX1 by NX-13 Alleviates Inflammatory Bowel Disease through Immunometabolic Mechanisms in CD4+ T Cells

Inflammatory bowel disease (IBD) is a complex autoimmune disease with dysfunction in pattern-recognition responses, including within the NLR family. Nucleotide-binding oligomerization domain, leucine rich repeat containing X1 (NLRX1) is a unique NLR with regulatory and anti-inflammatory functions resulting in protection from IBD in mouse models. NX-13 is an orally active, gut-restricted novel drug candidate that selectively targets and activates the NLRX1 pathway locally in the gut. In vitro and in vivo efficacy of NLRX1 activation by NX-13 was examined. Oral treatment with NX-13 alleviates disease severity, colonic leukocytic infiltration, and cytokine markers of inflammation in three mouse models of IBD (dextran sulfate sodium, Mdr1a^-/-, and CD45RB^hi adoptive transfer). Treatment of naive CD4⁺ T cells with NX-13 in vitro decreases differentiation into Th1 and Th17 subsets with increased oxidative phosphorylation and decreased NF-κB activation and Reactive Oxygen Species. With stimulation by PMA/ionomycin, TNF-α, or H₂O₂, PBMCs from ulcerative colitis patients treated with NX-13 had decreased NF-κB activity, TNF-α⁺ and IFN-γ⁺ CD4⁺ T cells and overall production of IL-6, MCP1, and IL-8. NX-13 activates NLRX1 to mediate a resistance to both inflammatory signaling and oxidative stress in mouse models and human primary cells from ulcerative colitis patients with effects on NF-κB activity and oxidative phosphorylation. NX-13 is a promising oral, gut-restricted NLRX1 agonist for treating IBD.