Short-term preoperative protein restriction attenuates vein graft disease via induction of cystathionine γ-lyase

Aims: Therapies to prevent vein graft disease, a major problem in cardiovascular and lower extremity bypass surgeries, are currently lacking. Short-term preoperative protein restriction holds promise as an effective preconditioning method against surgical stress in rodent models, but whether it can improve vein graft patency after bypass surgery is undetermined. Here, we hypothesized that short-term protein restriction would limit vein graft disease via up-regulation of cystathionine gamma-lyase and increased endogenous production of the cytoprotective gaseous signalling molecule hydrogen sulfide. Methods and results: Low-density lipoprotein receptor knockout mice were preconditioned for 1 week on a high-fat high-cholesterol (HFHC) diet with or without protein prior to left common carotid interposition vein graft surgery with caval veins from donor mice on corresponding diets. Both groups were returned to a complete HFHC diet post-operatively, and vein grafts analysed 4 or 28days later. A novel global transgenic cystathionine gamma-lyase overexpressing mouse model was also employed to study effects of genetic overexpression on graft patency. Protein restriction decreased vein graft intimal/media+adventitia area and thickness ratios and intimal smooth muscle cell infiltration 28days post-operatively, and neutrophil transmigration 4days post-operatively. Protein restriction increased cystathionine gamma-lyase protein expression in aortic and caval vein endothelial cells (ECs) and frequency of lung EC producing hydrogen sulfide. The cystathionine gamma-lyase inhibitor propargylglycine abrogated protein restriction-mediated protection from graft failure and the increase in hydrogen sulfide-producing ECs, while cystathionine gamma-lyase transgenic mice displayed increased hydrogen sulfide production capacity and were protected from vein graft disease independent of diet. Conclusion: One week of protein restriction attenuates vein graft disease via increased cystathionine gamma-lyase expression and hydrogen sulfide production, and decreased early inflammation. Dietary or pharmacological interventions to increase cystathionine gamma-lyase or hydrogen sulfide may thus serve as new and practical strategies to improve vein graft durability.