Galectin-3-Insights from Inflammatory Bowel Disease and Primary Sclerosing Cholangitis.

Inflammatory bowel disease (IBD) and primary sclerosing cholangitis (PSC) are related diseases with poorly understood pathophysiology. While therapy options for IBD have increased, treatment options for PSC remain limited. Galectin-3 is a multifunctional lectin expressed in intestinal epithelial cells, and is abundant in immune cells such as macrophages, with roles in cell adhesion, apoptosis, inflammation and fibrosis being associated with IBD and PSC disease development and progression. In addition, galectin-3 is also a visceral fat-derived protein whose systemic levels are increased in obese individuals, the latter correlating with a poorer prognosis in IBD and PSC patients. On the other hand, decreased galectin-3 expression in the inflamed mucosal tissues of mice and patients with IBD possibly indicate a protective role of this lectin in IBD. However, galectin-3 loss or inhibition is protective in most animal models of liver fibrosis but exacerbates the severity of autoimmune liver disease. Hence, with PSC being a slowly progressing autoimmune hepatobiliary disease closely related to IBD, further studies evaluating galectin-3 as a therapeutic target or biomarker for the severity of IBD and the occurrence of PSC are still needed. This review summarizes studies that have analyzed expression patterns and functions of galectin-3 in IBD and PSC. Current evidence suggests that strategies to block galectin-3 are not advised for patients with IBD and PSC-IBD.