complement factor D

Complement Factor D (CFD), also known as adipsin, is a serine protease that serves as the rate-limiting enzyme in the alternative complement pathway. It is primarily synthesized by adipocytes and is responsible for cleaving Factor B into Ba and Bb when Factor B is complexed with C3b, thereby forming the alternative pathway C3 convertase (C3bBb). Beyond its immunological role, Factor D acts as a female-enriched adipokine that regulates brown adipose tissue (BAT) thermogenesis and adipogenesis through the C3a/C3aR1 signaling axis. In pharmaceutical development, Factor D is a major therapeutic target for inhibitors (e.g., danicopan, vemircopan) used to treat complement-mediated disorders such as paroxysmal nocturnal hemoglobinuria (PNH) and geographic atrophy. Additionally, research into the CFD-C3aR1 pathway suggests potential therapeutic strategies for treating obesity and metabolic decline, particularly in males and postmenopausal women.

Other names

adipsinFactor Dproperdin factor DC3 convertase activatorC-3 convertase activatorC 3 convertase activatorproperdin factor D esterase