Bai Yuanyuan, Han Qingqing, Dong Beibei, Lin Huaying, Jiang Yi, Zhang Xinyue, Chen Hongguang, Yu Yonghao
Department of Anesthesiology, Tianjin Institute of Anesthesiology, General Hospital of Tianjin Medical University, Tianjin 300052, China.
Brain Res Bull. 2022 Jun 15;184:56-67. doi: 10.1016/j.brainresbull.2022.03.015. Epub 2022 Mar 30.
Sepsis-associated encephalopathy (SAE), a fatal complication of sepsis, contributes to cognitive impairment, high morbidity, and mortality. The molecular mechanism of hydrogen (H) administration, as a promising strategy for the treatment of SAE, is still unclear. Peroxisome proliferator-activated receptor α (PPARα) is essential for alleviating symptoms and complications of SAE. However, little is known about the role of PPARα in SAE. This study was designed to evaluate the expression of PPARα in SAE and determine whether H can alleviate SAE through regulation of the cAMP response element-binding protein (CREB)-brain-derived neurotrophic factor (BDNF) signaling pathway and its downstream proteins via PPARα. After the injection of GW6471 (the PPARα inhibitor) or GW7647 (the PPARα agonist) or saline, C57BL/6 J mice were subjected to cecal ligation and puncture (CLP) or sham operation, then treated with 2% H by inhalation for 1 h after the operation. The 7-day survival rate was recorded, and the Y-maze test was used to assess cognitive function. Apoptotic cells were observed by TUNEL staining, and brain tissues were collected for pathological analysis by H&E staining. In addition, the levels of pro-inflammatory and anti-inflammatory cytokines (TNF-α, IL-6, IL-18, HMGB1, and IL-1β) were measured by ELISA and the expression of PPARα, CREB, BDNF and other neurotrophins, postsynaptic density protein of 95 kDa (PSD95) by Western blot. The relationship between PPARα and the CREB-BDNF signaling pathway was explored by coimmunoprecipitation (CO-IP). The results showed the expression of PPARα was decreased in SAE mice and that activation of PPARα in septic mice improved the survival rate and alleviated cognitive dysfunction. Furthermore, PPARα may have exerted anti-inflammatory and anti-apoptotic effects in septic mice. In addition, the GW6471 downregulated the expression of CREB, BDNF and other neurotrophins in SAE mice treated with H. The expression of PSD95 was also downregulated and upregulated following the expression of PPARα. These results illustrated that H alleviates sepsis-induced brain injury in mice through the regulation of neurotrophins and hippocampal plasticity-related genes via PPARα by activating the CREB-BDNF signaling pathway.
脓毒症相关性脑病（SAE）是脓毒症的一种致命并发症，会导致认知障碍、高发病率和死亡率。氢气（H）吸入作为一种有前景的SAE治疗策略，其分子机制仍不清楚。过氧化物酶体增殖物激活受体α（PPARα）对减轻SAE的症状和并发症至关重要。然而，PPARα在SAE中的作用尚不清楚。本研究旨在评估SAE中PPARα的表达，并确定H是否能通过PPARα调节环磷酸腺苷反应元件结合蛋白（CREB）-脑源性神经营养因子（BDNF）信号通路及其下游蛋白来减轻SAE。向C57BL/6 J小鼠注射GW6471（PPARα抑制剂）或GW7647（PPARα激动剂）或生理盐水后，进行盲肠结扎和穿刺（CLP）或假手术，然后术后通过吸入2% H治疗1小时。记录7天生存率，并用Y迷宫试验评估认知功能。通过TUNEL染色观察凋亡细胞，收集脑组织进行苏木精-伊红（H&E）染色病理分析。此外，通过酶联免疫吸附测定（ELISA）测量促炎和抗炎细胞因子（肿瘤坏死因子-α、白细胞介素-6、白细胞介素-18、高迁移率族蛋白B1和白细胞介素-1β）水平，通过蛋白质免疫印迹法检测PPARα、CREB、BDNF和其他神经营养因子、95 kDa突触后致密蛋白（PSD95）的表达。通过免疫共沉淀（CO-IP）探究PPARα与CREB-BDNF信号通路之间的关系。结果显示，SAE小鼠中PPARα表达降低，脓毒症小鼠中PPARα激活可提高生存率并减轻认知功能障碍。此外，PPARα可能在脓毒症小鼠中发挥了抗炎和抗凋亡作用。另外，GW6471下调了H治疗的SAE小鼠中CREB、BDNF和其他神经营养因子的表达。PSD95的表达也随PPARα表达下调而上调。这些结果表明，H通过激活CREB-BDNF信号通路，经由PPARα调节神经营养因子和海马可塑性相关基因，从而减轻小鼠脓毒症诱导的脑损伤。
