CyCLoPs: a new approach to study how a cytokine influences IBD

Inflammatory Bowel Disease (IBD) is a long‑lasting chronic condition in which the intestine becomes damaged and inflamed. A healthy intestine relies on a tight barrier of cells that keeps harmful microbes out. When this barrier fails, bacteria leak in and drive more inflammation. A type of immune cell called a Th17 cell is central to this process. In health, Th17‑derived signals (cytokines) help intestinal cells make microbe‑killing molecules and repair damage. In disease, some of the same signals may impinge on intestinal epithelial cells and enteric neurons and attract large numbers of inflammatory cells, and can worsen tissue injury. Drugs that block one key cytokine, IL‑17A, work well in other diseases but have failed or even harmed patients with IBD, likely because we do not know exactly which cell types these cytokines act on in the gut. We have created new “reporter” mouse models that light up only in cells directly responding to IL-17A or in those expressing IL-17 receptors. Using these new tools, we will track responsive intestinal and nerve cells during health and different stages of colitis, and define how their gene expression changes. This work will guide the design of safer, more effective cytokine‑targeted therapies for IBD.