Lipid peroxidation product 4-hydroxy-2-nonenal acts synergistically with serotonin in inducing vascular smooth muscle cell proliferation.

Formation of an atherosclerotic lesion is in part mediated by inflammatory and oxidative mechanisms including lipid peroxidation. To characterize the potential role of lipid peroxidation products in atherogenesis, we assessed the effect of 4-hydroxy-2-nonenal (HNE), a component of oxidatively modified lipids on vascular smooth muscle cells (VSMCs) proliferation, and its interaction with serotonin (5-hydroxytryptamine, 5-HT), a known mitogen for VSMCs. Growth-arrested rabbit VSMCs were incubated with different concentrations of HNE in the absence or presence of 5-HT. VSMCs proliferation was examined by increases in [3H]thymidine incorporation into DNA and cell number. HNE and 5-HT stimulated DNA synthesis in a dose-dependent manner. HNE had a maximal proliferative effect at a concentration of 1 microM (143% of the control) and 5-HT at 50 microM (211%). When added together, low concentrations of HNE (0.1 microM) and 5-HT (5 microM) synergistically induced DNA synthesis (273%). These effects on DNA synthesis were paralleled by an increase in cell number. A 5-HT2 receptor antagonist LY 281067 (10 microg/ml) and pertussis toxin (10 ng/ml) inhibited the mitogenic effect of 5-HT only. Protein tyrosine kinase inhibitor erbstatin A (10 microM) completely inhibited the mitogenic effect of HNE and partially that of 5-HT and the combined effect of HNE+5-HT. Protein kinase C inhibitor Ro 31-8220 (0.1 microM) completely inhibited mitogenic effects of both HNE and 5-HT, and also the combined effect of HNE+5-HT. The synergistic effect of HNE+5-HT on DNA synthesis was completely reversed by the combined use of LY 281067 (10 microg/ml) and antioxidants N-acetylcysteine (400 microM), vitamin C (200 microM), or vitamin E (20 microM). Our results suggest that HNE acts synergistically with 5-HT in inducing VSMCs proliferation. Combined use of both antiplatelet and antioxidant therapies may be useful for the prevention of VSMCs proliferative disorders associated with atherosclerosis and restenosis after angioplasty.