IL-18 Small-Molecule Inhibitors to Prevent Intimal Hyperplasia and Vein Graft Failure

Abstract

INTRODUCTION: Upregulation of pro-inflammatory cytokines, including IL-18 has been attributed as a leading cause for the development of intimal hyperplasia and subsequent vein graft failure. As a result, an anti-IL-18 treatment strategy is an attractive platform for therapies. Here we present preliminary data on a new small molecule (sm) inhibitor of IL-18 we have identified in our laboratory. METHODS: In the present study, the IC50 value of this sm inhibitor was determined. Upon treatment with IL-18, the expression of IFN-γ gene and protein expression are increased in Natural Killer (NK) cells and hence NK cells were used to establish the in vitro sm inhibitor potency. NK cells were serum-starved for 4 hours, allowed to incubate with increasing concentrations (10 nM, 100 nM, 1 μM, and 10 μM) of the sm inhibitor for 2 hours and then treated with 50 ng/mL of IL-18. After 24 hours, the cells were harvested and IFN-γ gene expression was measured with qRT-PCR. RESULTS: IL-18 treatment resulted in 2.27 fold increase in IFN-γ gene expression while 10 nM, 100 nM, 1 μM, and 10 μM inhibitor concentrations resulted in a 0.8283, 0.7280, 0.5961 and 0.5201 fold decrease respectively in IFN-γ gene expression. The IC50 value for this compound was determined to be 12.36 μM. CONCLUSION: NK cell IFN-γ gene expression showed a significant (p < 0.05) dose-dependent decrease with increasing concentrations of the new small molecule inhibitor of IL-18. Further in vivo studies will be implemented to determine the compounds potential in decreasing the development of intimal hyperplasia.