The therapeutic potential of galectin-3 inhibition in fibrotic disease

Galectin-3 is a beta-galactoside-binding mammalian lectin and part of the 15 member Galectin family that are evolutionarily highly conserved. It is the only chimeric protein with a C-terminal carbohydrate recognition domain (CRD) linked to a proline, glycine, and tyrosine rich additional N-terminal domain. Galectin-3 binds several cell surface glycoproteins via its CRD domain as well as undergoing oligomerization, via binding at the N-terminal or the CRD, resulting in the formation of a Galectin-3 lattice on the cell surface. The Galectin-3 lattice has been regarded as being a crucial mechanism whereby extracellular Galectin-3 modulates cellular signalling by prolonging retention time or retarding lateral movement of cell surface receptors in the plasma membrane. As such Galectin-3 can regulate various cellular functions such as diffusion, compartmentalization and endocytosis of plasma membrane glycoproteins and glycolipids and the functionality of membrane receptors. In multiple models of organ fibrosis, it has been demonstrated that Galectin-3 is potently pro-fibrotic and modulates the activity of fibroblasts and macrophages in chronically inflamed organs. Increased Galectin-3 expression also activates myofibroblasts resulting in scar formation and may therefore impact common fibrotic pathways leading to fibrosis in multiple organs. Over the last decade there has been a marked increase in the scientific literature investigating Galectin-3 in a range of fibrotic diseases as well as the clinical development of new Galectin-3 inhibitors. In this review we will examine the role of Galectin-3 in fibrosis, the therapeutic strategies for inhibiting Galectin-3 in fibrotic disease and the clinical landscape to date.