METABOLOMICS ANALYSIS IDENTIFIED AN ORALLY ACTIVE METABOLITE FOR TREATING CROHN’S DISEASE-ASSOCIATED INTESTINAL FIBROSIS

Abstract

Abstract BACKGROUND Intestinal fibrosis is a debilitating complication of Crohn’s disease (CD) patients. Surgical resection is used to treat intestinal strictures, but this approach may adversely affect the patients' quality of life. Based on the findings of our groups and others, we hypothesize that intestinal metabolites are associated with intestinal fibrosis. We aimed to discover novel anti-fibrogenic metabolites. METHODS We compared the intestinal metabolite profiles between non-IBD, stricturing CD, and non-stricturing CD patients in an inflammatory bowel disease (IBD) multi-omics database to identify CD stricture-related metabolites. We compared the fecal metabolite profiles between trinitrobenzene sulfonic acid (TNBS)-treated mice with and without anti-fibrogenic CSA13 treatment to identify mouse intestinal fibrosis-related metabolites. RESULTS Compared to non-stricturing CD patients and non-IBD patients, stricturing CD patients had reduced fecal levels of inosine. Compared to normal mice, TNBS-treated mice had reduced fecal levels of inosine. CSA13-exposed TNBS-treated mice had increased fecal inosine levels. Oral administration of inosine (10 mg/kg/day for 14 days) effectively reduced ileal fibrosis in fibrotic 40-week-old SAMP1/YitFc mice with 96-100% reduction of intestinal collagen mRNA expression and 87% reduction of overall ileal disease activity. Although inosine did not directly inhibit collagen expression in primary human ileal fibroblasts from stricturing CD patients (CD-HIF), it reduced collagen mRNA expression in fresh ileal tissues from stricturing CD patients. RNA-seq and proteomics identified that peroxiredoxin 2 (PRDX2) is negatively associated with intestinal strictures in CD patients. PRDX2 is a thiol-specific antioxidant gene that reduces peroxides to alcohols. Inosine increased the secretion of peroxiredoxin 2 (PRDX2) in primary human intestinal epithelial cells (HPEC). The inosine-mediated PRDX2 secretion was inhibited by the pretreatment of adenosine 2A receptor (A2AR) inhibitor ZM241385. PRDX2 reduced cell stress, induced cell stress-related protein (cyclooxygenase 2/COX-2), and inhibited collagen expression in the CD-HIF. Inhibition of COX2 by indomethacin reversed the anti-fibrogenic effect of PRDX2 in the CD-HIF. Inhibition of PRDX2 caused increased collagen expression in the CD-HIF. Lentiviral overexpression of Prdx2 ameliorated ileal fibrosis in the fibrotic SAMP1/YitFc mice. Fibrotic SAMP1/YitFc mice had reduced circulating free thiol, reflecting increased systemic oxidative stress. Inosine restored circulating free thiol levels in SAMP1/YitFc mice. CONCLUSIONS Inosine is an orally active anti-fibrogenic metabolite that promotes PRDX2 expression from intestinal epithelial cells. PRDX2 is a newly identified anti-fibrogenic protein, which may inhibit collagen expression by reducing cell stress.