LBP reduces theinflammatory injuryof kidney in septic rat and regulates the Keap1-Nrf2∕ARE signaling pathway

Abstract Purpose: To investigate the influence of lycium barbarum polysaccharides (LBP), a functional derivative from lycium barbarum, on septic kidney injury. Methods: The SD male rats were randomly divided into 8 groups. The concentration of IL-1β, IL-6, IL-8, TNF-α, NF-κB and ROS, in kidney cortex homogenates after 12 h treatments were determined by enzyme-linked immunosorbent assay and ROS test kit, respectively. Morphology observation of kidney tissue was conducted with HE staining. The mRNA and protein expression levels of Nrf2, HO-1, NQO1, NF-κB, and Keap1 in kidney tissues were determined by qRT-PCR and Western blot, respectively. Results: LPS treatment significantly increased the oxidative stress. After LBP treatment, the ROS content reduced significantly in a dose-depend manner. However, the levels of HO-1, NQO1 and Nrf2 as molecular elements that respond to oxidative stress were further increased. Also, administration of LBP increased the levels of NF-κB and Keap1, and decreased the levels of Nrf2 in the Keap 1-Nrf2∕ARE signaling pathway. By administrating the brusatol, the inhibition of Nrf2 enhanced the expression of NF-κB, inhibits the antioxidant responses, and further reverse the protective effect of LBP on the LPS induced septic kidney injury. Conclusion: Lycium barbarum polysaccharides can reduce inflammation and activate the antioxidant responses via regulating the level of pro-inflammatory cytokines and the Keap1-Nrf2/ARE signaling pathway.

摘要 目的：探究枸杞（Lycium barbarum）的功能性衍生物枸杞多糖（Lycium barbarum polysaccharides, LBP）对脓毒症肾损伤的影响。
方法：将SD雄性大鼠随机分为8组。给药12小时后，分别采用酶联免疫吸附试验与活性氧（ROS）检测试剂盒，测定肾皮质匀浆中白细胞介素1β（IL-1β）、白细胞介素6（IL-6）、白细胞介素8（IL-8）、肿瘤坏死因子α（TNF-α）、核因子κB（NF-κB）及活性氧（ROS）的浓度。采用苏木精-伊红染色（HE staining）观察肾组织形态学变化。分别通过实时荧光定量反转录聚合酶链反应（qRT-PCR）与蛋白质印迹法（Western blot），检测肾组织中核因子E2相关因子2（Nrf2）、血红素氧合酶1（HO-1）、醌氧化还原酶1（NQO1）、核因子κB（NF-κB）及Kelch样ECH关联蛋白1（Keap1）的mRNA与蛋白表达水平。
结果：脂多糖（LPS）处理可显著升高氧化应激水平。经LBP处理后，ROS含量呈剂量依赖性显著降低。然而，作为氧化应激应答分子的血红素氧合酶1（HO-1）、醌氧化还原酶1（NQO1）及核因子E2相关因子2（Nrf2）的表达水平进一步升高。此外，LBP给药可上调Keap1-Nrf2/ARE信号通路中核因子κB（NF-κB）与Kelch样ECH关联蛋白1（Keap1）的水平，并降低核因子E2相关因子2（Nrf2）的表达。通过使用鸦胆子苦醇（brusatol）抑制Nrf2后，可增强NF-κB的表达、抑制抗氧化应答，并进一步逆转LBP对LPS诱导的脓毒症肾损伤的保护作用。
结论：枸杞多糖可通过调节促炎细胞因子水平及Keap1-Nrf2/ARE信号通路，减轻炎症反应并激活抗氧化应答。