The addition DNA Damage inhibitor of MVA rescued the inhibitory effect on cell proliferation caused
by atorvastatin in a dose-dependent manner (Fig. 2a). Similarly, the addition of MVA also abrogated the inhibitory effect of atorvastatin on IL-2 production in response to SEB in a dose-dependent manner (Fig. 2b), confirming that atorvastatin inhibits both superantigen-mediated lymphocyte proliferation and IL-2 production through inhibition of the mevalonate pathway acting at HMG-CoA reductase. The inflammatory response in acute KD is characterized by high levels of circulating TNF-α. TNF-α production is a key proinflammatory cytokine in the pathogenesis of coronary artery inflammation and elastin breakdown in the LCWE model of KD . Local production of TNF-α at the coronary artery leads
to up-regulation of MMP-9 production by vascular smooth muscle cells and localized elastolytic activity and matrix breakdown of affected coronary arteries [22,28]. To investigate the effect of atorvastatin on SAg-mediated TNF-α production, the supernatant of splenocytes co-cultured with SEB and atorvastatin was assayed by ELISA. Atorvastatin was able to inhibit TNF-α production dramatically (Fig. 3a). Furthermore, the addition of MVA abrogated Dabrafenib the inhibitory effect of atorvastatin on TNF-α production in a dose-dependent manner (Fig. 3b) indicating that, as in the case of IL-2, atorvastatin inhibits TNF-α production in response to SAg by interfering with the mevalonic pathway. In the LCWE disease model, MMP-9 production by vascular SMC at the coronary artery is directed by TNF-α. The production of MMP-9 leads to elastin breakdown and coronary vessel wall destruction [22,28]. To determine whether atorvastatin modulates TNF-α-induced MMP-9 production, MOVAS cells
were stimulated with TNF-α and atorvastatin and quantitative RT–PCR assay was used to determine MMP-9 transcription. Atorvastatin inhibited MMP-9 production in a dose-dependent fashion (Fig. 4a). The higher concentrations of atorvastatin required to exert an inhibitory effect may reflect the differential sensitivity to statin of different cell types PAK6 (i.e. SMC versus lymphocytes) and/or of different cellular pathways (i.e. proliferation and cytokine production versus MMP-9 production). The observed inhibitory effects were not due to the diluant (DMSO) used to deliver atorvastatin to the cell culture system. DMSO was assayed for potential toxic effects and was found to have no effect on cell proliferation at the concentrations used (Fig. S1; see Supporting information at end). To determine whether the MEK/extracellular-regulated kinase (ERK) signalling pathway was responsible for atorvastatin-mediated inhibition of MMP-9 production, the effects of atorvastatin on ERK phosphorylation was determined by phospho-Western blots on MOVAS cells stimulated with TNF-α and given atorvastatin.