Pselectinen

P-selectin, also known as CD62P or SELP, is a cell adhesion molecule that plays a crucial role in the inflammatory response and hemostasis. It is a transmembrane protein belonging to the selectin family of adhesion molecules, which are characterized by a carbohydrate-binding lectin domain. P-selectin is primarily expressed on activated platelets and endothelial cells.

In the context of inflammation, when endothelial cells are activated by inflammatory mediators such as histamine, TNF-alpha, or IL-1, P-selectin rapidly translocates from intracellular granules (Weibel-Palade bodies) to the cell surface. This surface expression allows P-selectin to bind to specific carbohydrate ligands on leukocytes, particularly on neutrophils and monocytes. This initial binding is transient and facilitates the rolling adhesion of leukocytes along the activated endothelium, a critical step for their subsequent migration into inflamed tissues.

P-selectin also plays a significant role in blood clotting. Upon platelet activation, for instance, during vascular injury, P-selectin is rapidly mobilized to the platelet surface. Here, it can bind to its ligand PSGL-1 (P-selectin glycoprotein ligand-1) on other platelets, contributing to platelet aggregation and thrombus formation. This interaction is important for maintaining hemostasis and can also contribute to pathological clot formation in conditions like atherosclerosis.

The involvement of P-selectin in both inflammation and thrombosis has made it a target for therapeutic intervention. Blocking P-selectin activity has been explored as a strategy to reduce leukocyte recruitment in inflammatory diseases and to prevent unwanted clot formation.