Circulating and Tissue Galectin-3 in Gastrointestinal Inflammation: Clinical Significance and Biomarker Potential

Galectins represent a family of widely expressed lectins that have the ability to bind β-galactoside in modulating "cell-to-cell" and "cell-to-matrix" interactions in all organisms. These proteins are expressed in many inflammatory cells, such as macrophages, and depending on the inflammatory environment, they promote pro-inflammatory or anti-inflammatory responses. Galectin-3 (Gal-3) is predominantly located in the cytoplasm, but, as noted, it has also been detected in the nucleus, on the cell surface and in the extracellular environment, which indicates the multifunctionality of this molecule. It has been shown in many studies that Gal-3 is involved in immune regulation, fibrosis, and tissue remodeling, making it an important player in disorders such as inflammatory bowel disease (IBD), non-alcoholic steatohepatitis (NASH), and liver fibrosis. In IBD, this protein is associated with activation of the NLRP3 inflammasome, contributing to chronic intestinal inflammation. Also, in primary biliary cholangitis and autoimmune hepatitis, Gal-3 potentiate development of fibrosis through fibroblast-to-myofibroblast transition and extracellular matrix deposition, while in liver fibrosis, it is upregulated in hepatic stellate cells and macrophages, promoting fibrosis and inflammation. Studies show that Gal-3 inhibition reduces fibrosis and inflammation, making it a promising therapeutic target.