Group V sPLA 2 Hydrolysis of Low-Density Lipoprotein Results in Spontaneous Particle Aggregation and Promotes Macrophage Foam Cell Formation

• Published in: Arteriosclerosis, thrombosis, and vascular biology Vol. 24; no. 4; pp. 762 - 767
• Main Authors: Wooton-Kee, C. Ruth, Boyanovsky, Boris B., Nasser, Munira S., de Villiers, Willem J.S., Webb, Nancy R.
• Format: Journal Article
• Language: English
• Published: 01.04.2004
• ISSN: 1079-5642; 1524-4636
• DOI: 10.1161/01.ATV.0000122363.02961.c1

Objectives— Secretory phospholipase A 2 (sPLA 2 ) enzymes hydrolyze the sn-2 fatty acyl ester bond of phospholipids to produce a free fatty acid and a lysophospholid. Group V sPLA 2 is expressed in cultured macrophage cells and has high affinity for phosphatidyl choline-containing substrates. The present study assesses the presence of group V sPLA 2 in human and mouse atherosclerotic lesions and its activity toward low-density lipoprotein (LDL) particles. Methods and Results— Group V sPLA 2 was detected in human and mouse atherosclerotic lesions by immunohistochemical staining. Electron microscopic analysis showed that mouse group V sPLA 2 -modified LDL is significantly smaller (mean diameter±SEM=25.3±0.25 nm) than native LDL (mean diameter±SEM=27.7±0.29 nm). Hydrolysis by group V sPLA 2 induced spontaneous particle aggregation; the extent of aggregation was directly proportional to the degree of LDL hydrolysis. Group V sPLA 2 modification of LDL led to enhanced lipid accumulation in cultured mouse peritoneal macrophage cells. Conclusions— Group V sPLA 2 may play an important role in promoting atherosclerotic lesion development by modifying LDL particles in the arterial wall, thereby enhancing particle aggregation, retention, and macrophage uptake.