Proteome analysis of human monocytic THP-1 cells primed with oxidized low-density lipoproteins

Native low-density lipoprotein (LDL) and oxidized LDL (oxLDL) possess a wide variety of biological properties, and play a central role in atherogenesis. In this study, we used a proteomic analysis of human monocyte THP-1 cells induced with oxLDL or with LDL, to identify proteins potentially involved in atherosclerotic processes. Of the 2500 proteins detected, 93 were differentially expressed as a result of priming with LDL or oxLDL. The proteins were unambiguously identified by comparing the masses of their tryptic peptides with those of all known proteins using MALDI-TOF MS and the NCBI database. The largest differences in expression were observed for vimentin (94-fold increase), meningioma-expressed antigen 6 (48-fold increase), serine/threonine protein phosphatase 2A (40-fold increase), and beta-1,3-galactosyltransferase (15-fold increase). In contrast, the abundance of an unnamed protein product and phosphogluconate dehydrogenase decreased 30-fold and 25-fold, respectively. The expression of some selected proteins was confirmed by Western blot and RT-PCR analyses. The proteins identified in this study are attractive candidates for further biomarker research. This description of the altered protein profiles induced by oxLDL in human monocytes will support functional studies of the macrophage-derived foam cells involved in the pathogenesis of atherosclerosis.