CCR9 and inflammatory bowel disease: The biological role of the CCR9-CCL25 axis and the evidence implicating CCR9, and CCL25 in gut inflammation in both human and murine IBD, suggest this is an appropriate pathway to target therapeutically.10,29,39,50,51 However, the involvement of CCR9 and CCL25 in immune regulation and tolerance raises valid concerns that under some circumstances inhibition could be detrimental.