Endothelial dysfunction is associated with the initiation of sepsis-associated organ failure. Bacterial quorum-sensing molecules act as pathogen-associated molecular patterns; however, the effects of quorum-sensing molecules on endothelial cells remain less understood. This study investigated the molecular mechanisms of quorum sensing molecule-induced cell death and their interaction with lipopolysaccharide (LPS) in human umbilical vein endothelial cells. Endothelial cells were treated with N-3-oxododecanoyl homoserine lactone (3OC12-HSL) and LPS derived from Pseudomonas aeruginosa. Treatment with 3OC12-HSL reduced cell viability in a dose-dependent manner, and co-treatment with 3OC12-HSL and LPS enhanced cell death. Terminal deoxynucleotidyl transferase deoxyuridine triphosphate nick end labeling assay revealed an increase in apoptotic cell death following 3OC12-HSL treatment; furthermore, co-treatment with 3OC12-HSL and LPS enhanced apoptosis. Western blotting revealed that treatment with 3OC12-HSL activated the receptor-interacting protein kinase 1 (RIPK1) pathway, leading to an increase in the levels of cleaved caspase 8 and 3. In addition, we found that treatment with necrostatin-1, an RIPK1 inhibitor, reduced cell death and ameliorated the activation of the RIPK1-dependent apoptotic pathway in 3OC12-HSL-treated cells. In conclusion, 3OC12-HSL induced endothelial cell apoptosis via the activation of the RIPK1 pathway, independent of LPS toxicity. Inhibition of RIPK1 may act as a therapeutic option for preserving endothelial cell integrity in patients with sepsis by disrupting the mechanism by which quorum-sensing molecules mediate their toxicity.

中文翻译：

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N-3-氧代十二烷酰高丝氨酸内酯通过诱导受体相互作用蛋白激酶 1 依赖性细胞凋亡加剧内皮细胞死亡

内皮功能障碍与脓毒症相关器官衰竭的开始有关。细菌群体感应分子充当病原体相关分子模式；然而，群体感应分子对内皮细胞的影响仍然知之甚少。这项研究调查了群体感应分子诱导细胞死亡的分子机制及其与人脐静脉内皮细胞中脂多糖 (LPS) 的相互作用。用 N-3-氧代十二烷酰基高丝氨酸内酯 (3OC12-HSL) 和来自铜绿假单胞菌的 LPS 处理内皮细胞。3OC12-HSL 治疗以剂量依赖性方式降低细胞活力，3OC12-HSL 和 LPS 共同治疗增强细胞死亡。末端脱氧核苷酸转移酶脱氧尿苷三磷酸缺口末端标记分析显示 3OC12-HSL 处理后凋亡细胞死亡增加；此外，与 3OC12-HSL 和 LPS 共同处理可增强细胞凋亡。蛋白质印迹显示，用 3OC12-HSL 处理激活受体相互作用蛋白激酶 1 (RIPK1) 通路，导致裂解的 caspase 8 和 3 水平增加。此外，我们发现用 necrostatin-1（一种 RIPK1）处理抑制剂，减少细胞死亡并改善 3OC12-HSL 处理细胞中 RIPK1 依赖性细胞凋亡途径的激活。总之，3OC12-HSL 通过激活 RIPK1 通路诱导内皮细胞凋亡，与 LPS 毒性无关。