Department of Cardiology, the First Affiliated Hospital of Chongqing Medical University, Chongqing 400016, China; Institute of Life Science, Chongqing Medical University, Chongqing 400016, China.
Department of Cardiology, the First Affiliated Hospital of Chongqing Medical University, Chongqing 400016, China.
Int Immunopharmacol. 2021 Apr;93:107388. doi: 10.1016/j.intimp.2021.107388. Epub 2021 Jan 30.
Endothelial dysfunction is a typical characteristic of sepsis. Endothelial nitric oxide synthase (eNOS) is important for maintaining endothelial function. Our previous study reported that the NLRP3 inflammasome promoted endothelial dysfunction by enhancing inflammation. However, the effects of NLRP3 on eNOS require further investigation. Therefore, the present study aimed to investigate the role of NLRP3 on eNOS expression levels in cecal ligation and puncture-induced impaired endothelium-dependent vascular relaxation and to determine the protective effects of melatonin. eNOS expression levels were discovered to be downregulated in the mesenteric arteries of sepsis model mice. Inhibiting NLRP3 with 10 mg/ kg MCC950 or inhibiting IL-1β with 100 mg diacerein rescued the eNOS expression and improved endothelium-dependent vascular relaxation. In vitro, IL-1β stimulation downregulated eNOS expression levels in human aortic endothelial cells (HAECs) in a concentration- and time-dependent manner, while pretreatment with 1 µM of the proteasome inhibitor MG132 reversed this effect. In addition, treatment with 10 mg/kg MG132 also prevented the proteolysis of eNOS and improved endothelium-dependent vascular relaxation in vivo. Notably, treatment with 30 mg/kg melatonin downregulated NLRP3 expression levels and decreased IL-1β secretion, subsequently increasing the expression of eNOS and improving endothelium-dependent vascular relaxation. In conclusion, the findings of the present study indicated that the NLRP3/IL-1β axis may impair vasodilation by promoting the proteolysis of eNOS and melatonin may protect against sepsis-induced endothelial relaxation dysfunction by inhibiting the NLRP3/IL-1β axis, suggesting its pharmacological potential in sepsis.
内皮功能障碍是脓毒症的典型特征。内皮型一氧化氮合酶（eNOS）对于维持内皮功能非常重要。我们之前的研究报道，NLRP3 炎性小体通过增强炎症促进内皮功能障碍。然而，NLRP3 对 eNOS 的影响需要进一步研究。因此，本研究旨在探讨 NLRP3 在盲肠结扎和穿刺诱导的受损内皮依赖性血管舒张中对 eNOS 表达水平的作用，并确定褪黑素的保护作用。研究发现，脓毒症模型小鼠肠系膜动脉中的 eNOS 表达水平下调。用 10mg/kg MCC950 抑制 NLRP3 或用 100mg 双醋瑞因抑制 IL-1β 可挽救 eNOS 表达并改善内皮依赖性血管舒张。在体外，IL-1β 刺激以浓度和时间依赖性方式下调人主动脉内皮细胞（HAEC）中的 eNOS 表达水平，而用 1µM 蛋白酶体抑制剂 MG132 预处理可逆转这种作用。此外，用 10mg/kg MG132 处理还可防止 eNOS 的蛋白水解，并改善体内内皮依赖性血管舒张。值得注意的是，用 30mg/kg 褪黑素处理可下调 NLRP3 表达水平并减少 IL-1β 分泌，从而增加 eNOS 的表达并改善内皮依赖性血管舒张。总之，本研究结果表明，NLRP3/IL-1β 轴可能通过促进 eNOS 的蛋白水解来损害血管舒张，而褪黑素可能通过抑制 NLRP3/IL-1β 轴来保护脓毒症引起的内皮舒张功能障碍，提示其在脓毒症中的药理学潜力。
