The Experimental Study On The Effects Of Aspirin And Fluvastatin On The Inhibition Of Proliferation Of Human Umbilical Artery Smooth Muscle Cells Through Transforming Growth Factor β1

Inflammation plays a pivotal role in the development and progression of atherosclerotic lesions, in which many factors, such as cytokines, are involved. Transforming growth factor- β (TGF- β ) occupies an important nexus in the web of cell signaling involving in inflammation and controlling blood vessel wall structure. Studies suggest that TGF- β can function as an inhibitor and also a strong predictor of atherosclerotic disease. Aspirin and HMG-CoA ruductase inhibitors(Statins) are nowadays routine therapies in atherosclerotic diseases sharing some new and even common mechanisms that need to be explored. Objective:To investigate new mechanisms of aspirin and fluvastatin in the treatment of atherosclerosis, focusing on their inhibition of VSMCs proliferation through TGF-β 1 signaling and the effects on the level of TGF- β 1 mRNA in cultured VSMCs. To investigate the role of TGF- β 1 in inhibition of atherosclerosis and maintenance of plaque stability. Methods:Human umbilical artery smooth cells (HUASMCs) were isolated and cultured in vitro incubated with or without specific anti-TGF- β 1 neutralizing antibody. Cell proliferation and cell cycles were measured by MTT and flow cytometry(FCM) after treated with different levels of aspirin or fluvastatin. The level of TGF- β 1 mRNA in cultured HUASMCs were detected by RT-PCR. Plaques obtained from biopsy or autopsy were analyzed for TGF- β 1 expression by immuno-cytochemistry staining to investigate the contribution of TGF- β 1 to the inhibition of atherosclerosis and maintenance of plaque stability.Results:The proliferation of HUASMCs were inhibited by aspirin or fluvastatin in a dose-dependent manner (P <0.05) in vitro, independent of the cytotoxicity of either medicine. The anti-proliferation effects can be reversed by specific anti-TGF-Pl neutralizing antibody(/> <0.05). Either aspirin (2.0mmol/L) or fluvastatin (1.0 u mol/L) restrained cells in GO phase (PO.05), while the effect of aspirin (2.0mmol/L) , but not fluvastatin (1.0 u mol/L) , can be reversed by specific anti-TGF- P 1 neutralizing antibody(/> <0.05). The levels of TGF- P 1 mRNA in cultured HUASMCs were increased by aspirin or fluvastatin or their combination^ <0.05). Elevated levels of TGF- P 1 were recorded in the intima of early stage atherosclerostic samples versus normal arteries and advanced atherosclerostic lesions respectively^ <0.05) and in stable plaques versus unstable plaques (y°<0.05)by immunocytochemistry staining. Conclusions:1. TGF- P 1 plays a pivotal role in atherosclerosis as protective cytokine.2. Aspirin or fluvastatin, independent of their cytotoxicity, can inhibit the proliferation of HUASMCs in a dose-dependent manner in vitro, in which TGF- P 1 signaling might be involved to some extent. 3. Either aspirin or fluvastatin inhibits the proliferation of HUASMCs by arresting cells in GO phase.4. Aspirin or fluvastatin can increase the levels of TGF- P 1 mRNA in cultured HUASMCs in vitro. Their combination might enhance the effects on the transcription of TGF- P 1 mRNA.