Nageswaran, V.; Carreras, A.; Reinshagen, L.; Beck, K. R.; Steinfeldt, J.; Stahlman, M.; Ramezani Rad, P.; Lim, J.; Strässler, E. T.; Verhaar, B. J. H.; Döring, Y.; Weber, C.; König, M.; Steinhagen-thiessen, E.; Demuth, I.; Kränkel, N.; Leistner, D. M.; Nieuwdorp, M.; Knaus, P.; Ferrell, M.; Potente, M.; Hazen, S. L.; Landmesser, U.; Bäckhed, F.; Haghikia, A.

Background: The microbially generated amino acid-derived metabolite imidazole propionate (ImP) contributes to the pathogenesis of type 2 diabetes. However, the effect of ImP on endothelial cell physiology and its role in atherosclerotic coronary artery disease (CAD) is unknown. Using both human and animal models, we investigated the potential role of ImP in atherosclerosis. Methods: Plasma levels of ImP were measured in 831 patients undergoing elective cardiac angiography using UHPLC-MS/MS. Odds ratios and 95% confidence intervals for CAD were calculated based on ImP quartiles using univariable and multivariable logistic regression models. Atheroprone Apoe-/- mice fed a high-fat diet were treated with ImP (800 ug) or vehicle, and aortic atherosclerotic lesion area was evaluated after 12 weeks. In a mouse model of carotid artery injury, the effect of ImP on vascular regeneration was examined. The impact of ImP on functional properties of human aortic endothelial cells was assessed. Next-generation sequencing, western blot analysis, siRNA-based gene knockdown, and tamoxifen-inducible Cre-loxP experiments were performed to investigate ImP-mediated molecular mechanisms. Results: Plasma ImP levels in patients were associated with increased risk for prevalent CAD. In atheroprone Apoe-/- mice, ImP increased atherosclerotic lesion size. ImP dose-dependently impaired migratory and angiogenic properties of endothelial cells and promoted an increased inflammatory response. Long-term exposure to ImP impaired the repair potential of the endothelium after arterial insult. Mechanistically, ImP attenuated insulin receptor signaling by suppressing the PI3K/AKT pathway, leading to sustained activation of the forkhead box protein O1 (FOXO1) transcription factor. Genetic inactivation of endothelial FOXO1 signaling in ImP-treated mice enhanced angiogenic activity and preserved the vascular repair capacity of endothelial cells after carotid injury. Conclusions: Our findings reveal an unknown role of the microbially produced histidine-derived metabolite ImP in endothelial dysfunction and atherosclerosis, suggesting that ImP metabolism is a potential therapeutic target in atherosclerotic cardiovascular disease.