CCR9

Class

Chemokine receptor antagonist

CCR9 is a chemokine receptor, a cell-surface protein that responds to a small signaling protein called a chemokine, in this case CCL25. It is expressed mainly on subsets of lymphocytes and directs their migration into the small intestine, where CCL25 is produced by intestinal epithelial cells. This receptor-ligand pair acts as a homing signal, guiding immune cells to gut tissue. In chronic inflammatory bowel diseases such as Crohn's disease, excessive recruitment and retention of these lymphocytes in the intestinal mucosa contributes to tissue damage and persistent inflammation. Blocking CCR9 with an antagonist interrupts this homing signal, reducing the influx of pathogenic lymphocytes into the gut without broadly suppressing the immune system elsewhere in the body. This tissue-selective rationale distinguishes CCR9 antagonism from systemic immunosuppressants, aiming to limit gut inflammation while sparing immune surveillance in other organs. The mechanism is studied primarily in gastrointestinal inflammatory conditions where lymphocyte trafficking to the intestine is a central disease driver, offering a more targeted alternative to therapies that dampen immune function throughout the body.