User:Immcarle141/Addressin

Addressin is a lesser-used term to describe the group of adhesion molecules that are involved with lymphocyte homing, commonly found at high-endothelial venules (HEVs) where lymphocytes exit the blood and enter the lymph node.

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Addressins physically bind to mobile lymphocytes to guide them to the HEVs. Examples of molecules that are often referred to as addressins are CD34 and GlyCAM-1 on HEVs in peripheral lymph nodes, and MAdCAM-1 on endothelial cells in the intestine.

Therapies
In inflammatory bowel diseases, MAdCAM-1 can be overexpressed on the endothelial cells of intestinal mucosa and gut‐associated lymphoid tissue, leading to excessive inflammation in the gut. A potential therapeutic target to manage these diseases could be the MAdCAM-1 molecules that are expressed on these cells and bring in lymphocytes. One example of a potential therapy is the fully human monoclonal antibody ontamalimab that targets and binds to MAdCAM-1, preventing it from interacting with the integrins on the surface of the lymphocytes.

PNAd
Peripheral node addressins (PNAd) are carbohydrate residues that are lymphocyte homing receptor ligands that are expressed on the HEVs of peripheral lymph nodes. These proteins collectively bind to L-selectin to guide lymphocytes such as mature naïve B and T cells into the lymph node. During the development of secondary lymphoid organs, PNAd expression is upregulated following the upregulation and subsequent downregulation of MAdCAM-1 on HEVs. PNAd expression, as well as the expression of MAdCAM-1, is dependent on lymphotoxin signaling in the HEVs of lymph nodes.