中国药科大学Li Liu等研究人员合作发现，硫酸吲哚酚-TNFα轴介导啮齿动物急性肾损伤中的尿毒症脑病。2024年4月8日，《中国药理学报》杂志在线发表了这项成果。

研究人员表示，急性肾损伤（AKI）通常伴有尿毒症脑病，其原因可能是血脑屏障（BBB）功能受损导致尿毒症毒素在脑内蓄积。阴离子尿毒症毒素是有机阴离子转运体（OAT）的底物或抑制剂。

研究人员调查了AKI大鼠和小鼠分别腹腔注射顺铂8mg/kg和20mg/kg后的中枢神经系统行为，以及BBB OAT3的表达/功能。结果表明，顺铂治疗显著抑制了AKI大鼠和小鼠脑内OAT3、突触素和微管相关蛋白2（MAP2）的表达，损害了其运动和探索活动，并增加了尿毒症毒素在脑内的蓄积。体外研究表明，尿毒症毒素既不会改变人脑微血管内皮细胞中 OAT3 的表达，也不会改变人神经母细胞瘤（SH-SY5Y）细胞中突触素和MAP2的表达。

相反，肿瘤坏死因子α（TNFα）和用硫酸吲哚酚（IS）处理的RAW264.7细胞的条件培养基（CM）会显著影响OAT3的表达。TNFα和经IS处理的BV-2细胞的CM也抑制了SH-SY5Y细胞中突触素和MAP2的表达。体外TNFα和CM以及体内AKI和TNFα引起的改变均被英夫利昔单抗（一种用于拦截和中和TNFα的单克隆抗体）所消除，这表明AKI通过IS诱导巨噬细胞或小胶质细胞释放TNFα（称为IS-TNFα轴）来损害大脑中OAT3、突触素和MAP2的表达。

用TNFα处理小鼠（0.5mg/kg每天，腹腔注射，3天）会显著增加p-p65的表达，并降低Nrf2和HO-1的表达。抑制NF-κB通路、沉默p65或激活Nrf2和HO-1可明显减轻TNFα诱导的OAT3、突触素和MAP2表达下调。在AKI小鼠和大鼠脑中还检测到p-p65蛋白水平显著升高，Nrf2和HO-1蛋白水平显著降低。研究人员认为，AKI抑制OAT3、突触素和MAP2的表达是由于IS诱导巨噬细胞或小胶质细胞释放TNFα所致。TNFα部分通过激活NF-κB通路和抑制Nrf2-HO-1通路来影响OAT3、突触素和MAP2的表达。

附：英文原文

Title: Indoxyl sulphate-TNFα axis mediates uremic encephalopathy in rodent acute kidney injury

Author: Jiang, Ling, Sun, Xue-ying, Wang, Si-qian, Liu, Yan-lin, Lu, Ling-jue, Wu, Wen-han, Zhi, Hao, Wang, Zhong-yan, Liu, Xiao-dong, Liu, Li

Issue&Volume: 2024-04-08

Abstract: Acute kidney injury (AKI) is often accompanied by uremic encephalopathy resulting from accumulation of uremic toxins in brain possibly due to impaired blood-brain barrier (BBB) function. Anionic uremic toxins are substrates or inhibitors of organic anionic transporters (OATs). In this study we investigated the CNS behaviors and expression/function of BBB OAT3 in AKI rats and mice, which received intraperitoneal injection of cisplatin 8 and 20mg/kg, respectively. We showed that cisplatin treatment significantly inhibited the expressions of OAT3, synaptophysin and microtubule-associated protein 2 (MAP2), impaired locomotor and exploration activities, and increased accumulation of uremic toxins in the brain of AKI rats and mice. In vitro studies showed that uremic toxins neither alter OAT3 expression in human cerebral microvascular endothelial cells, nor synaptophysin and MAP2 expressions in human neuroblastoma (SH-SY5Y) cells. In contrast, tumour necrosis factor alpha (TNFα) and the conditioned medium (CM) from RAW264.7 cells treated with indoxyl sulfate (IS) significantly impaired OAT3 expression. TNFα and CM from IS-treated BV-2 cells also inhibited synaptophysin and MAP2 expressions in SH-SY5Y cells. The alterations caused by TNFα and CMs in vitro, and by AKI and TNFα in vivo were abolished by infliximab, a monoclonal antibody designed to intercept and neutralize TNFα, suggesting that AKI impaired the expressions of OAT3, synaptophysin and MAP2 in the brain via IS-induced TNFα release from macrophages or microglia (termed as IS-TNFα axis). Treatment of mice with TNFα (0.5mg·kg1·d1, i.p. for 3 days) significantly increased p-p65 expression and reduced the expressions of Nrf2 and HO-1. Inhibiting NF-κB pathway, silencing p65, or activating Nrf2 and HO-1 obviously attenuated TNFα-induced downregulation of OAT3, synaptophysin and MAP2 expressions. Significantly increased p-p65 and decreased Nrf2 and HO-1 protein levels were also detected in brain of AKI mice and rats. We conclude that AKI inhibits the expressions of OAT3, synaptophysin and MAP2 due to IS-induced TNFα release from macrophages or microglia. TNFα impairs the expressions of OAT3, synaptophysin and MAP2 partly via activating NF-κB pathway and inhibiting Nrf2-HO-1 pathway.

DOI: 10.1038/s41401-024-01251-6

Source: https://www.nature.com/articles/s41401-024-01251-6