What mechanism leads to angioedema?

Angioedema is characterized by the rapid swelling of the deeper layers of the skin, often around the eyes and lips, and occasionally the throat. The mechanism underlying angioedema involves bradykinin, a peptide that plays a crucial role in vascular permeability. When bradykinin binds to its B2 receptors on endothelial cells, it induces changes that increase the permeability of blood vessels. This increased permeability allows fluids to escape from the bloodstream into the surrounding tissues, leading to the swelling and inflammation characteristic of angioedema.

Bradykinin's role in angioedema is particularly relevant in certain conditions, such as hereditary angioedema, where there is a deficiency or dysfunction in C1 inhibitor, which normally regulates the complement and contact pathway of the coagulation cascade. Without adequate regulation, there is excess production of bradykinin, resulting in swelling.

While histamine release from mast cells is often associated with allergic reactions and urticaria (hives), it primarily causes allergic-type swellings rather than the deeper swelling characteristic of angioedema. Serotonin and prostaglandins generally play roles in other inflammatory pathways and are not the primary mediators of angioedema. Therefore, understanding the