Role of leukotriene B4 receptors in the development of atherosclerosis: potential mechanisms.
OBJECTIVE: Leukotriene B4 (LTB4), a potent leukocyte chemoattractant, is known to promote several inflammatory diseases, including atherosclerosis. We sought to determine mechanisms through which LTB4 modulates atherosclerosis in cell lines expressing LTB4 receptors, BLT-1, and in mice deficient in BLT-1 as well as macrophage cell lines derived from BLT-1+/+ and BLT-1-/- mice. METHODS AND RESULTS: Analysis of global changes in gene expression induced by LTB4 in rat basophilic leukemia cells (RBL-2H3) expressing the human BLT-1 showed highest-fold increase in expression of fatty acid translocase/ CD36 and the chemokine MCP1/JE/ CCL2, which are critical in atherogenesis. To determine the importance of BLT-1 in atherogenesis, we crossed BLT-1-null mice with apolipoprotein (apo)-E-deficient mice, which develop severe atherosclerosis. Deletion of BLT-1 significantly reduced the lesion formation in apo-E-/- mice only during initiating stages (4 and 8 weeks) but had no effect on the lesion size in mice fed atherogenic diet for 19 weeks. Macrophage cell lines from BLT-1-deficient mice expressed the low-affinity LTB4 receptor, BLT-2, and exhibited chemotaxis to LTB4. CONCLUSIONS: The effects of LTB4 in atherosclerosis are likely mediated through the high-affinity BLT-1 and the low-affinity BLT-2 receptors. LTB4 promotes atherosclerosis by chemo-attracting monocytes, by providing an amplification loop of monocyte chemotaxis via CCL2 production, and by converting monocytes to foam cells by enhanced expression of CD36 and fatty acid accumulation.[1]References
- Role of leukotriene B4 receptors in the development of atherosclerosis: potential mechanisms. Subbarao, K., Jala, V.R., Mathis, S., Suttles, J., Zacharias, W., Ahamed, J., Ali, H., Tseng, M.T., Haribabu, B. Arterioscler. Thromb. Vasc. Biol. (2004) [Pubmed]
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