Inflammation and Atherosclerosis Group IIa and Group V sPLA2 Are Not Redundant

The secretory phospholipase A2 (sPLA2) family hydro-lyzes glycerophospholipids at the sn-2 position togenerate lysophospholipids and free fatty acids. Ten members have been described in mammals. These enzymes must be clearly distinguished from the intracellular phospho-lipase A2s that are involved in intracellular signaling. They are also distinct from lipoprotein-associated phospholipase A2 (Lp-PLA2), which has been shown to be bound predomi-nantly to LDL particles in human plasma, and hydrolyzes oxidized LDL to generate lysophosphatidylcholine and oxi-dized nonesterified fatty acids.1 Group IIa sPLA2, which was originally isolated from rheumatoid arthritis fluids, is consid-ered to be the prototypic inflammatory sPLA2. Its expression is markedly elevated in many cell types in response to proinflammatory stimuli. The concentration of Group IIa sPLA2 in sera or exudating fluids correlates well with the severity of inflammatory disease. In humans, Group IIa an