Identification of S100A9 as a target for diagnosis and treatment of Crohn's Disease after Vedolizumab treatment failure.

The vedolizumab medication is the treatment that precisely targets the gut for Crohn's Disease (CD). It can inhibit the migration of lymphocytes to the intestinal site despite the fact that a significant portion of the population continues to be ineffectively treated. In this study, peripheral blood leukocytes sampled from the CD patients who are nonresponsive or responsive to vedolizumab treatment were used for transcriptome sequencing. Intersected differentially expressed mRNA obtained from transcriptome sequencing and GSE191328 were utilized to predict key therapeutic targets. Bioinformatics analyses were used to explore potential biological mechanisms and to screen pivotal genes. Inhibitor of S100A9 increased the body weight and colon length of mice with colitis, and decreased the DAI score. Our study also demonstrated that the combination of anti-α4β7 integrin antibody with inhibitor of S100A9 further alleviates colitis. Through flow cytometry, changes in the composition of immune cell populations in colon tissues were found after intragastric administration of paquinimod, an inhibitor of S100A9. It is important that blocking S100A9 inhibited the recruitment of neutrophils in the mice's colon. Our findings lay a foundation for the further exploration of the new targets for non-responders to vedolizumab in CD patients.