A chronic liver disease known as primary sclerosing cholangitis (PSC) has been linked to inflammatory bowel disease (IBD) in the past. But the connection between the two disorders has been unclear, especially as the liver condition often develops years after IBD has resolved or the colon has been surgically removed. Eksteen and colleagues now show that T cells that were activated in the gut - probably during IBD - are found in the livers of patients with PSC, but not in those of patients with other inflammatory liver diseases.
The authors explain this detour by showing that an attractant protein that normally directs T cells into the gut is aberrantly produced in the liver during PSC. T cells expressing the receptor for the protein are thus re-routed to the liver, although the authors do not know what triggers liver cells to make the attractant in the first place. T cells can survive as memory cells for many years after they are activated, and the authors believe this may explain how the liver disease can crop up years after IBD has resolved.