P077 The Immunometabolic Bimodal Mechanism of NLRX1 Agonist NX-13 in a Pig Model of Ulcerative Colitis

Abstract

Abstract Background In mouse models, NX-13 is an orally active, gut-restricted NLRX1 agonist that has been shown to reduce severity of disease in multiple UC models through a novel immunometabolic, bimodal mechanism. Most preclinical UC studies rely upon rodent models, the human gastrointestinal physiology, microbiome, and immune system bear a greater similarity to that of pigs. Therefore, we sought to expand and validate our preclinical NX-13 results in mice using the dextran sulfate sodium (DSS) pig model of colitis. Here, we describe the disease severity, cellular, and biomarker results, and confirm the immunometabolic MOA observed in other species. Methods Pigs were randomized by weight (n=6 per group) and were administered tablets of excipient alone (placebo), NX-13 10 mg, NX-13 50 mg, or NX-13 100mg once daily. Pigs were challenged with 1% DSS in drinking water for 6 days and monitored daily for weight gain (loss). Composite disease activity score (0-12) was taken based on the sum of three subscores (0-4) for rectal bleeding, stool consistency and overall health/activity. Necropsy was conducted on day 7. Feces were collected for fecal calprotectin (FCP) quantification. Colonic tissue was macroscopically scored and collected for analysis by flow cytometry, histopathology and gene expression. Results Oral NX-13 treatment protected against weight loss and reduced colitis development with differences as early as day 2, becoming significant between days 4 and 6 as disease worsens in placebo treated pigs (Fig1A). NX-13 yielded a dose-dependent improvement in macroscopic lesion severity and microscopic immune cell infiltration (Fig1B). Specifically, Th1 cells (Fig1C) and TNF producing myeloid cells in the colonic lamina propria were reduced by NX-13, as well as FCP levels in stool (Fig1D) and mRNA expression in the colon (Fig1E). Oral NX-13 treatment reduced inflammatory markers including TNF, monocyte and neutrophil chemo attractants, IL-6, and IL-23 (Fig3F). Additionally, NX-13 treatment affected markers specific to the bimodal immunometabolic MOA of NLRX1 activation, namely upregulation of NLRX1 and mitochondrial metabolism gene COX3 (Fig1G), and reduction of NFkB and NLRP3 (Fig1H). Conclusion NX-13 demonstrated fast and clinically meaningful improvement in disease activity, and significantly impacted on key inflammatory markers in a DSS colitis model in pigs. These results align with previous murine results and observations in the phase 1b clinical program. Therefore, they can be used to generate additional mechanistic hypotheses for translational studies in the ongoing NEXUS phase 2 trial in moderate to severe UC.