Identification of genes potentially involved in rupture of human atherosclerotic plaques

Although rupture of an atherosclerotic plaque is the major cause of acute v ascular occlusion, the exact molecular mechanisms underlying this process a re still poorly understood. In this study, we used suppression subtractive hybridization to make an inventory of genes that are differentially express ed in whole-mount human stable and ruptured plaques. Two libraries were gen erated, one containing 3000 clones upregulated and one containing 2000 clon es downregulated in ruptured plaques. Macroarray analysis of 500 randomly c hosen clones showed differential expression of 45 clones. Among the 25 clon es that showed at least a 2-fold difference in expression was the gene of p erilipin, upregulated in ruptured plaques, and the genes coding for fibrone ctin and immunoglobutin lambda chain, which were downregulated in ruptured plaques. Reverse transcriptase-polymerase chain reaction analysis on 10 ind ividual ruptured and 10 individual stable plaques showed a striking consist ency of expression for the clones SSH6, present in 8 ruptured and 2 stable plaques, and perilipin, expressed in 8 ruptured plaques and completely abse nt in stable plaques. Localization studies of both perilipin mRNA and prote in revealed expression in cells surrounding the cholesterol clefts and in f oam cells of ruptured atherosclerotic plaques. No expression was observed i n nondiseased artery, and only a few cells in the shoulder region of stable plaques tested positive for perilipin. In conclusion, this study shows tha t it is possible to identify genes that are differentially expressed in who le-mount stable or ruptured atherosclerotic plaques. This approach may yiel d several potential regulators of plaque destabilization.