The role of phospholipase A2 in the physiopathology of osteoarthritis.
High activity of phospholipase A2 (PLA2) was found in 58 synovial fluids of patients with osteoarthritis (OA), with a range of 2.2-75.1 nmol/min/ml and mean +/- SEM of 22.0 +/- 1.4 nmol/min/ml. This PLA2 was a calcium dependent enzyme composed of 2 isoforms called A and B. Twelve of 25 patients with OA (48%) were found to have high circulating PLA2, but no correlation to the numbers or size of affected joints was found. High concentrations of PLA2 were detected in human articular cartilage ranging from 33 to 4257 nmol/min/mg protein. The deep layers of the cartilage contained on average 3-fold more PLA2 than the superficial layers. Also synovial cells cultures and chondrocyte cultures that derived from OA joints synthesized and released PLA2 extracellularly. Since PLA2 is proinflammatory, its role in the inflammation that complicates OA process is highly probable. Further studies of PLA2 impact on OA joints and clinical trials with PLA2 inhibitors in OA are warranted.
Pruzanski
W
W
Inflammation Research Group, Wellesley Hospital, University of Toronto, ON, Canada.
Bogoch
E
E
Wloch
M
M
Vadas
P
P
D002358:Cartilage, Articular / Q000201:enzymology / Q000473:pathology / Q000503:physiopathology; D002478:Cells, Cultured; D006801:Humans; D010003:Osteoarthritis / Q000209:etiology / Q000473:pathology / Q000503:physiopathology*; D010741:Phospholipases A / Q000378:metabolism / Q000502:physiology*; D054467:Phospholipases A2; D013582:Synovial Fluid / Q000201:enzymology / Q000502:physiology
D010741:Phospholipases A; D054467:Phospholipases A2