Analysis of secretory group II phospholipase A(2) expression in human aortic tissue in dependence on the degree of atherosclerosis

Secretory non-pancreatic (group II) phospholipase A(2) (sPLA(2)) releases p recursors of important mediators of inflammation from phospholipids. Based on the inflammatory character of atherosclerosis we previously described th e identification of sPLA(2) in human atherosclerotic plaques. In vitro stud ies on lipoproteins have shown that sPLA(2) is able to favour the formation of foam-like cells representing a typical feature of early atherosclerotic lesions. In the present study the expression of sPLA(2) in relation to the degree of atherosclerosis was investigated. Aortic tissue samples of 25 au topsy cases ranging in age from 1 to 77 years were taken from 2 cm above th e heart and 3 cm below the renal arteries. The material was classified rega rding the degree of atherosclerotic changes based on staining with haemalau n and eosine as well as on staining according to Goldner. Furthermore, immu nohistochemical procedures detecting sPLA(2), macrophages and smooth muscle cells were performed. The study has shown that in the abdominal aorta the enzyme was present in all advanced atherosclerotic lesions, but only in som e preatheromas and precursors of atherosclerosis. However, this correlation did not occur in the thoracic aorta, where sPLA(2)-positive results showed a similar frequency in all degrees of atherosclerotic lesion. The enzyme w as found in all three layers of the vessel wall without significant differe nces. Round cells, scarcely smooth muscle cells and endothelial cells were identified as sPLA(2)-positive. However, these data do not allow a conclusi on as to which type of cell is responsible for the secretion of sBLA(2). In summary, the correlation between the expression of this enzyme and the deg ree of atherosclerosis underlines the possible importance of sPLA(2) in ath erogenesis. (C) 1999 Elsevier Science Ireland Ltd. All rights reserved.