MAdCAM1s

MAdCAM-1, or mucosal addressin cell adhesion molecule 1, is a member of the immunoglobulin superfamily that functions as an adhesion molecule in the immune system. It is a cell-surface glycoprotein primarily expressed on high endothelial venules in mucosal tissues, especially the gut-associated lymphoid tissue, including Peyer's patches and the lamina propria. MAdCAM-1 guides lymphocytes to gut mucosa during immune surveillance.

The protein mediates its effects by binding to the integrin α4β7, which is expressed on a subset of circulating T and B lymphocytes. Interaction between α4β7 and MAdCAM-1 supports the tethering, rolling, and eventual firm adhesion of lymphocytes, directing them to mucosal sites. Structurally, MAdCAM-1 is a transmembrane glycoprotein with extracellular immunoglobulin-like domains, a single transmembrane region, and a cytoplasmic tail.

Expression is largely constitutive in gut HEVs but can be upregulated under inflammatory conditions, contributing to enhanced lymphocyte recruitment during intestinal inflammation. While predominantly associated with mucosal tissues, MAdCAM-1 expression has also been observed in certain inflammatory or disease-associated vascular beds.

Clinically, the MAdCAM-1/α4β7 axis is a key pathway in intestinal immune cell trafficking. Increased MAdCAM-1 expression is noted in inflammatory bowel diseases, and therapies that disrupt the interaction, such as antibodies against α4β7 integrin, reduce gut-specific lymphocyte recruitment and inflammation. Research continues into direct targeting of MAdCAM-1 itself as a therapeutic approach.

In humans, MAdCAM-1 is encoded by the MADCAM1 gene, with conserved orthologs in other mammals, reflecting its role in mucosal immunity across species.