Sepsis-associated encephalopathy (SAE) is a cognitive impairment caused by sepsis and is related to increased morbidity and mortality. Damage to the blood–brain barrier (BBB) has been proved to be one of the important causes of SAE. Molecular hydrogen (H₂) is a promising method for the treatment of SAE, yet the underlying mechanism is not clear. This study was designed to demonstrate whether H₂ can alleviate SAE by protecting the BBB, and whether it is protected by Nuclear factor erythroid-2-related factor 2 (Nrf2) and its downstream signaling pathways. Either a sham or a cecal ligation and puncture (CLP) procedure was applied to female wild-type (WT) and Nrf2-knock-out (Nrf2^-/-) C57BL/6J mice. H₂ (2%) was given for 60 min starting at 1 h and 6 h after the sham or CLP procedure. In addition, bEnd.3 cells cultured with medium which contained LPS, Saline, DMSO or ML385 (a Nrf2 inhibitor) were also used in the research. The 7-day survival rates were recorded. The Morris water maze was used to determine cognitive function. Pro-inflammatory and anti-inflammatory cytokines [tumor necrosis factor-alpha (TNF-α), interleukin 6 (IL-6), HMGB1, and IL-10), antioxidant enzymes, and oxidation products [superoxide dismutase (SOD), chloramphenicol acetyltransferase (CAT), malondialdehyde (MDA), and (8-iso-PGF2α)] were determined by enzyme-linked immunosorbent assay (ELISA). Brain water content, Dextran tracer, and Evans blue extravasation were used to detect the damage of the BBB. Western blot analysis was used to detect β-catenin, phosphorylated β-catenin, adhesion-linked protein VE-cadherin, and associated tight junction protein ZO-1. We found that H₂ can improve survival in septic mice, decrease escape latency and platform crossing times, decrease pro-inflammatory cytokines and oxidative product levels in the mouse cortex, and increase the expression of anti-inflammatory factors in WT, but not Nrf2^-/-, mice. Moreover, H₂ can also decrease brain water content, extravascular dextran, extravascular Evans blue dye, and β-catenin level, and increase ZO-1 and VE-cadherin expressions in WT mice, but not in Nrf2^-/- mice. Our result shows that H₂ can protect the BBB by decreasing its permeability, thereby reducing SAE and improving cognitive function, which is mediated through Nrf2 and its downstream signaling pathways.

败血症相关性脑病（SAE）是由败血症引起的认知障碍，与发病率和死亡率增加有关。血脑屏障（BBB）的破坏已被证明是SAE的重要原因之一。分子氢（H ₂）是一种治疗SAE的有前途的方法，但其潜在机理尚不清楚。这项研究旨在证明H ₂是否可以通过保护BBB减轻SAE，以及是否受到核因子erythroid-2相关因子2（Nrf2）及其下游信号通路的保护。将假手术或盲肠结扎穿孔术（CLP）应用于雌性野生型（WT）和Nrf2-敲除（Nrf2 ^-/-）C57BL / 6J小鼠。高₂（2％）在假手术或CLP手术后1小时和6小时开始服用60分钟。此外，还使用了含有LPS，盐水，DMSO或ML385（一种Nrf2抑制剂）的培养基培养的bEnd.3细胞。记录7天生存率。莫里斯水迷宫被用来确定认知功能。促炎和抗炎细胞因子[肿瘤坏死因子-α（TNF-α），白介素6（IL-6），HMGB1和IL-10），抗氧化酶和氧化产物[超氧化物歧化酶（SOD），氯霉素通过酶联免疫吸附测定（ELISA）测定乙酰转移酶（CAT），丙二醛（MDA）和（8-iso-PGF2α）]。脑含水量，右旋糖酐示踪剂和伊文思蓝外渗被用来检测血脑屏障的损害。蛋白质印迹分析用于检测β-catenin，磷酸化的β-catenin，黏着连接蛋白VE-cadherin和相关的紧密连接蛋白ZO-1。我们发现H₂可以改善败血症小鼠的存活率，减少逃避潜伏期和平台穿越时间，降低小鼠皮质中的促炎细胞因子和氧化产物水平，并增加WT中抗炎因子的表达，但不能增加Nrf2 ^-/-小鼠。此外，H ₂还可降低WT小鼠的脑含水量，血管外右旋糖酐，血管外伊文思蓝染料和β-连环蛋白水平，并增加ZO-1和VE-钙粘蛋白的表达，而在Nrf2 ^-/-小鼠中则不然。我们的结果表明，H ₂可以通过降低BBB的渗透性来保护BBB，从而降低SAE并改善认知功能，这是通过Nrf2及其下游信号传导途径介导的。