FIDAXOMICIN INHIBITS INTESTINAL FIBROSIS VIA PLATELET-DERIVED GROWTH FACTOR RECEPTOR BETA AND GLYCOGEN SYNTHASE KINASE 3.

Introduction: About 30-50% of Crohn’s disease patients develop intestinal strictures. Intestinal strictures are often caused by intestinal fibrosis. There is no approved medication to prevent and treat intestinal fibrosis. The aim was to discover new targets and therapeutic approaches against intestinal fibrosis.
Methods: Spatial RNA sequencing, high-throughput drug screening, molecular docking, and protein arrays were used to discover new targets for intestinal fibrosis. Stricturing CD (CDS) patient-derived primary intestinal fibroblasts (CD-HIF), CDS patient-derived serum exosomes (CDSE), fresh intestinal tissues, and an animal model of intestinal fibrosis were also used. CDSE mimicked the CDS environment and induced fibrogenesis in CD-HIF.
Results: We performed spatial RNA sequencing with ileal biopsies from adult CDS patients to identify local fibrosis-related genes in strictures. We compared our spatial RNA sequencing data with the whole-transcriptome RNA sequencing of ileal biopsies from pediatric CD patients and found several commonly up-regulated ileal stricture-related genes. The siRNA knockdown of these several stricture-related genes identified platelet-derived growth factor receptor beta (PDGFRB) as the only gene mediating collagen COL1A1 promoter activity and protein expression in CDSE-treated CD-HIFs. High-throughput screening of 2621 FDA-approved drugs identified platelet-derived growth factor receptor beta (PDGFRβ) inhibitors suppressing collagen promoter activity in CDSE-treated CD-HIF. Two molecular docking algorithms predicted the binding of Fidaxomicin to PDGFR. Fidaxomicin is a safe and FDA-approved drug for treating C. difficile infection. CDSE increased PDGFRβ and downstream glycogen synthase kinase 3 alpha/beta (GSK3α/β) phosphorylation levels in the CD-HIF. Similarly, ileal tissues from CDS patients had higher PDGFβ and GSK3α/β phosphorylation levels than those from non-stricturing CD patients. Fidaxomicin inhibited collagen expression and PDGFRβ and GSK3α/β phosphorylation in CDSE-treated CD-HIF. Fidaxomicin also downregulated PDGFRB mRNA expression in CDSE-treated CD-HIF and CDS patient-derived ileal tissues. The anti-fibrogenic effect of fidaxomicin was reversed by platelet-derived growth factor-BB (PDGF-BB), a ligand of PDGFRβ, and insulin-like growth factor 1 (IGF-1), an activator of GSK3α/β phosphorylation. Inhibitors of PDGFRβ (Gleevec) and GSK3α/β (SB415286) reduced collagen expression in CDSE-treated CD-HIF. In the SAMP1/YitFc mice with spontaneous ileal fibrosis, oral administration of Fidaxomicin inhibited ileal fibrosis, which was abolished by Igf1 and Pdgfrb overexpression.
Conclusions: PDGFRβ and GSK3α/β are actionable molecular targets in intestinal fibrosis. Fidaxomicin inhibited GSK3α/β phosphorylation and PDGFRβ phosphorylation expression in CD-HIF, leading to anti-fibrogenic effects.