Drug Repurposing to Inhibit Oncostatin M in Crohn’s Disease

Crohn's disease is an inflammatory bowel disease (IBD) that currently lacks satisfactory treatment options. Therefore, new targets for new drugs are urgently needed to combat this disease. In the present study, we investigated the transcriptomics-based mRNA expression of intestinal biopsies from patients with Crohn's disease. We compared the mRNA expression profiles of the ileum and colon of patients with those of healthy individuals. A total of 72 genes in the ileum and 33 genes in the colon were differentially regulated. Among these, six genes were overexpressed in both tissues, including <i>IL1B</i>, <i>TCL1A</i>, <i>HCAR3</i>, <i>IGHG1</i>, <i>S100AB</i>, and <i>OSM</i>. We further focused on <i>OSM</i>/oncostatin M. To confirm the responsiveness of intestinal tissues from patients with Crohn's disease to oncostatin M inhibition, we examined the expression of the oncostatin M using immunohistochemistry in patient biopsies as well as in kindlin-1^-/- and kindlin-2^-/- knockout mice, which exhibit an inflammatory bowel disease (IBD) phenotype, and found strong oncostatin M expression in all samples examined. Next, we conducted a drug-repurposing study using the supercomputer MOGON and bioinformatic methods. A total of 13 candidate compounds out of 1577 FDA-approved drugs were identified by PyRx-based virtual drug screening and AutoDock-based molecular docking. Their lowest binding energies (LBEs) ranged from -10.46 (±0.08) to -8.77 (±0.08) kcal/mol, and their predicted inhibition constants (pK_i) ranged from 21.62 (±2.97) to 373.78 (±36.78) nM. Ecamsule has an interesting stereostructure with two C₂-symmetric enantiomers (1<i>S</i>,4<i>R</i>-1'<i>S</i>,4'<i>R</i> and 1<i>R</i>,4<i>S</i>-1'<i>R</i>,4'<i>S</i>) (<b>1a</b> and <b>1b</b>) and one <i>meso</i> diastereomer (1<i>S</i>,4<i>R</i>-1'<i>R</i>,4'<i>S</i>) (<b>1c</b>). These three stereoisomers showed strong, albeit differing, binding affinities in molecular docking. As examined by nuclear magnetic resonance and polarimetry, the 1<i>S</i>,4<i>R</i>-1'<i>S</i>,4'<i>R</i> isomer was the stereoisomer present in our commercially available preparations used for microscale thermophoresis. Ecamsule (<b>1a</b>) was chosen for in vitro validation using recombinant oncostatin M and microscale thermophoresis. Considerable dissociation constants were obtained for ecamsule after three repetitions with a K_d value of 11.36 ± 2.83 µM. Subsequently, we evaluated, by qRT-PCR, the efficacy of ecamsule (<b>1a</b>) as a potential drug that could prevent oncostatin M activation by inhibiting downstream inflammatory marker genes (<i>IL6</i>, <i>TNFA</i>, and <i>CXCL11</i>). In conclusion, we have identified oncostatin M as a promising new drug target for Crohn's disease through transcriptomics and ecamsule as a potential new drug candidate for Crohn's disease through a drug-repurposing approach both in silico and in vitro.