Cardiac endothelial cells produce complement C3 in response to hypoxia

Abstract Hypoxia takes places in life threatening conditions, such as heart attack. Endothelial cells are on the first line being affected when hypoxia occurs. Complements as innate immune factors have been reported to play an important role in re-oxygenation after hypoxia being corrected, but little is known the complement response in endothelia cells during hypoxia. Using a murine cardiac endothelial line H5V, we investigated this. Under hypoxia condition without serum (thus no exogenous complements provided), these cardiac endothelial cells produced complement C3 for a period time and died. However, when serum was supplemented during hypoxia, these cells did not produce endogenous C3 and maintained a reasonable survival rate. The results indicate that endogenous production of complement C3 is promoted by the hypoxia stress and linked to cell death of cardiac endothelial cells.