PHOSPHOLIPASES A(2) AND INFLAMMATORY PATH OLOGY - CONSENSUS AND NEW CONCEPTS

Besides their digestive or metabolic functions, phospholipases A? (PLA ,) are essentially known for their role in the synthesis of lipid medi ators, which requires the liberation of various precursors such as ara chidonic acid. In the last past years, a number of enzymes have been c haracterized, among which cytosolic PLA(2) (cPLA(2)) and type II PLA(2 ), also called ''secretory'' PLA(2) or sPLA(2). Whereas there is a con sensus about the role and regulation of cPLA(2), the real function of sPLA(2), which is produced in response to inflammatory stimuli, still remains largely unknown. A recent study proposes that sPLA(2) could ac t on microvesicles shed from activated cells after loss of phospholipi d asymmetry. Among phospholipids then becoming accessible to this extr acellular enzyme, phosphatidic acid, which is produced via two main si gnalling pathways, thus appears as a potential precursor of lysophosph atidic acid, a novel phospholipid mediator with diverse biological act ivities. Together with the discovery of a receptor for secreted PLA(2) , these new data open interesting issues in various fields of pathophy siology and pharmacology.