'Paneth Cells' Appearing in the Colon of Ulcerative Colitis Patients Found to Aid Wound Repair (Institute of Science Tokyo)

Explanation

On August 4, 2026, a research team led by Assistant Professor Tsuyoshi Ito of the Center for the Promotion of Longevity and Healthy Life / Department of Gastroenterology, Institute of Science Tokyo Hospital, announced the mechanism by which "Paneth cell metaplasia," which appears in the colon of ulcerative colitis patients, aids wound repair.

In ulcerative colitis, inflammation occurs in the mucosa of the colon, and the tissue repeatedly cycles through injury and repair. It has long been known that cells resembling Paneth cells, which are normally found mainly in the small intestine, appear in the colon of these patients—a phenomenon called "Paneth cell metaplasia." It has been reported since at least the 1960s and has long been considered a tissue change associated with chronic inflammation, but why it occurs was not known.

Examination of tissue revealed that Paneth cell metaplasia was found more often in the colons of patients whose disease had lasted more than 10 years, and at sites where inflammation was active. Verification using miniature intestines and mice revealed that the protein "IL-22," released from immune cells, triggers Paneth cell metaplasia, and that the antimicrobial peptide "REG3A" secreted from these cells helps close wounds by increasing the number of colon cells.

This achievement demonstrates that this phenomenon, which had been regarded as an abnormal tissue change, actually has a role in healing wounds, and it is hoped this will lead to new treatments utilizing REG3A.

Published paper: DOI 10.1038/s41467-026-71136-1