Milk fat globule-epidermal growth factor 8 (MFG-E8) attenuates sepsis-induced acute kidney injury by inhibiting NF-κB signaling pathway

Abstract Purpose: To explore the effect of milk fat globule-epidermal growth factor 8 (MFG-E8) on sepsis-induced acute kidney injury (SAKI). Methods: Male C57BL/6 mice were randomized to control, sham, CLP, CLP+PBS, and CLP+rmMFG-E8 groups. SAKI was induced by cecal ligation and puncture (CLP). Recombinant mouse MFG-E8 (rmMFG-E8) (20 μg/kg) or PBS (vehicle) was administered intraperitoneally. Blood, urine and renal tissue were collected at 24 h after CLP. Blood samples were tested for serum kidney injury biomarker and cytokines. Urine samples were collected to detect KIM-1, and NGAL. Real-time PCR was tested for Bax and Bcl-2. TUNEL staining was used to determine renal apoptosis. Western blot was used to detect the expression of Bax, Bcl-2, and proteins in the NF-κB pathway. Results: MFG-E8 alleviated SAKI by decreasing serum Cre, BUN, urine KIM-1 and NGAL and by mitigating renal pathological changes significant (p < 0.05). IL-1β, IL-6, TNF-α were significantly inhibited by MFG-E8 (p < 0.05). Apoptosis induced by SAKI was markedly suppressed by MFG-E8. Finally, MFG-E8 attenuated the activation of the NF-��B signaling pathway in SAKI. Conclusion: MFG-E8 has beneficial effects on SAKI, which may be achieved by inhibiting the NF-κB pathway.

摘要 目的：探讨乳脂肪球-表皮生长因子8（milk fat globule-epidermal growth factor 8, MFG-E8）对脓毒症诱导急性肾损伤（sepsis-induced acute kidney injury, SAKI）的影响。方法：将雄性C57BL/6小鼠随机分为对照组、假手术组、盲肠结扎穿刺（cecal ligation and puncture, CLP）组、CLP+磷酸盐缓冲液（phosphate buffered saline, PBS）组及CLP+重组小鼠MFG-E8（rmMFG-E8）组。采用盲肠结扎穿刺法构建脓毒症诱导急性肾损伤模型，通过腹腔注射给予重组小鼠MFG-E8（20 μg/kg）或磷酸盐缓冲液作为溶剂对照。于模型构建后24 h采集血液、尿液及肾组织样本：检测血液样本中的血清肾损伤生物标志物与细胞因子；收集尿液样本检测肾损伤分子1（kidney injury molecule-1, KIM-1）与中性粒细胞明胶酶相关脂质运载蛋白（neutrophil gelatinase-associated lipocalin, NGAL）；采用实时荧光定量PCR检测Bax及Bcl-2的mRNA表达水平；采用TUNEL染色检测肾组织细胞凋亡情况；采用蛋白质印迹法检测Bax、Bcl-2及核因子-κB（nuclear factor-κB, NF-κB）通路相关蛋白的表达水平。结果：MFG-E8可通过降低血清肌酐（Creatinine, Cre）、尿素氮（blood urea nitrogen, BUN）水平，减少尿液中KIM-1与NGAL的表达，并显著减轻肾组织病理损伤（P<0.05），从而缓解脓毒症诱导急性肾损伤；MFG-E8可显著抑制IL-1β、IL-6及TNF-α的表达（P<0.05）；MFG-E8可显著抑制脓毒症诱导的肾组织细胞凋亡；此外，MFG-E8可减弱脓毒症诱导急性肾损伤小鼠肾组织中NF-κB信号通路的激活。结论：MFG-E8对脓毒症诱导急性肾损伤具有保护作用，其机制可能与抑制NF-κB信号通路的激活相关。