Suppressive effects of anti-inflammatory agents on human endothelial cell activation and induction of heat shock proteins

Background: Studies from our laboratory have shown that the earliest stages of atherosclerosis may be mediated by an autoimmune reaction against heat shock protein 60 (Hsp60). The interactions of Hsp60-specific T cells with a rterial endothelial cells (EC) require expression of both Hsp60 and certain adhesion molecules shown to be induced simultaneously in EC by mechanical and other types of stress. Recently, it was shown that suppression of T cel l-mediated immune responses by cyclosporin A (CyA) enhanced atherosclerotic lesion formation in mice. Ih contrast, aspirin was found to lower the risk of myocardial infarction in men. These conflicting observations may be due to different effects of anti-inflammatory agents on adhesion molecule and Hsp expression in EC, respectively. Material and Methods: In the present study, we analyzed the effects of CyA, aspirin, and indomethacin on T cell proliferation using a proliferation as say. To explore the expression of adhesion molecules, monocyte chemoattract ant protein-1 (MCP-1), and Hsp60 in human umbilical vein endothelial cells (HUVECs), Northern blot analyses were used. To examine the activation statu s of the transcription factors nuclear factor kappa B (NF-kappa B) and heat shock factor-1 (HSF-1), electrophoretic mobility shift assays were perform ed. Results: With the exception of indomethacin, the used immunosuppressive and anti-inflammatory agents significantly inhibited T cell proliferation in r esponse to influenza virus antigen in a dose-dependent manner. interestingl y CyA and indomethacin did not suppress tumor necrosis factor-alpha (TNF-al pha)-induced adhesion molecule expression on HUVECs, whereas aspirin had an inhibitory effect. These observations correlated with the modulation of NF -kappa B activity in EC. All agents tested induced expression of Hsp60 6 hr after application. in addition, aspirin and indomethacin, but not CyA, ind uced Hsp70 expression in HUVECs that correlated with induction of HSF-1 act ivity. Conclusion: Our results show chat the tested agents (except indomethacin) a re inhibitors of the T cell-mediated immune response, as expected, that asp irin is an effective suppressor of adhesion molecule expression, and that a ll three agents can induce Hsp60 in HUVECs. These data provide the molecula r basis for the notion that (1) part of the anti-atherogenic effect of aspi rin may be due to the prevention of the adhesion of sensitized T cells to s tressed EC; (2) that part of the atherosclerosis promoting effect of CyA ma y be due to its potential as an inducer of Hsp60 expression and its inabili ty to down-regulate adhesion molecule expression on EC; and (3) that down-r egulation of MCP-1 expression by aspirin may result in decreased recruitmen t of monocytes into the arterial intima beneath stressed EC.