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肝X受体减轻肾脏缺血/再灌注损伤

黄英枝¹, 栾志琳², 刘舒静², 张聪², 明文华², 任保印¹, 管又飞², 张晓燕^1,*

¹华东师范大学医学与健康研究院，上海 200241；²大连医科大学医学科学研究院，大连 116044

摘要

急性肾损伤(acute kidney injury, AKI)是由各种病因引起的肾功能快速下降而出现的临床综合征。肾缺血/再灌注损伤(renal ischemia-reperfusion injury, RIRI)是导致AKI 的主要原因之一，但RIRI 的发生机制尚未完全阐明。肝X 受体(liver Xreceptors, LXRs)是核受体超家族成员，有两种亚型，即LXRα 和LXRβ。研究表明LXRs在调节糖脂代谢、促进胆固醇外流、减轻炎症等方面发挥着重要作用。本研究旨在探讨LXRs在RIRI 中发挥的作用及机制，以期为相关疾病的治疗提供理论依据和潜在靶点。我们在小鼠RIRI 模型和人肾皮质近端小管细胞系(HK2)细胞缺氧/复氧(hypoxia/reoxygenation, H/R)模型中观察LXRs激活对肾脏功能和细胞损伤的作用。体内研究结果显示，LXRs激动剂GW3965 可显著抑制RIRI 引起的小鼠血肌酐、尿素氮水平的升高；HE和PAS染色结果显示，GW3965 明显减轻RIRI 导致的肾组织形态损伤；免疫组织化学染色结果显示，GW3965 明显降低肾脏4-HNE和GRP78 水平；TUNEL染色结果显示，GW3965 显著抑制RIRI 导致的肾脏细胞凋亡；实时荧光定量PCR (quantitative real-time PCR, qPCR)结果显示，GW3965 抑制RIRI 导致的IL-6 和IL-1β 转录水平的上调。然而，与野生型相比，LXRα 基因敲除对于RIRI 引起的肌酐、尿素氮水平的上升以及肾小管的细胞受损没有明显影响。细胞实验结果显示，GW3965 可明显缓解H/R 导致的HK2 细胞活力降低；超氧化物歧化酶(superoxide dismutase, SOD)检测结果显示，GW3965 抑制细胞H/R 后的SOD活性下降；Western blot 结果显示，GW3965 抑制细胞H/R 后4-HNE和GRP78 蛋白水平的上调；而在HK2 细胞中用小干扰RNA (small interfering RNA, siRNA)敲低LXRβ 可抵消GW3965 对细胞活力的影响。本研究结果提示，LXRs 激动剂GW3965 可显著减轻小鼠RIRI，其机制可能与减轻细胞凋亡、氧化应激、内质网应激及炎症反应相关，本研究结果初步证实了LXRs激动剂的肾脏保护作用依赖于LXRβ。

关键词： 急性肾损伤; 缺血/再灌注; 肝X受体; GW3965

Liver X receptor attenuates renal ischemia-reperfusion injury in mice

HUANG Ying-Zhi¹, LUAN Zhi-Lin², LIU Shu-Jing², ZHANG Cong², MING Wen-Hua², REN Bao-Yin¹, GUAN You-Fei², ZHANG Xiao-Yan^1,*

¹Health Science Center, East China Normal University, Shanghai 200241, China；²Advanced Institute for Medical Sciences, Dalian Medical University, Dalian 116044, China

Abstract

Acute kidney injury (AKI) is a clinical syndrome characterized by a rapid decline in renal function. Renal ischemiareperfusion injury (RIRI) is one of the main causes of AKI with the underlying mechanism incompletely clarified. The liver X receptors (LXRs), including LXRα and LXRβ, are members of the nuclear receptor superfamily. It has been shown that LXRs play an important role in regulating glucose and lipid metabolism, cholesterol efflux, and inflammation. The purpose of this study was to explore the role and mechanism of LXRs in RIRI. We determined the effects of LXR activation on renal function and histological changes in a mouse RIRI model and a cellular model of hypoxia/reoxygenation (H/R). In vivo results showed that LXRs agonist GW3965 significantly inhibited the increase of serum creatinine and urea nitrogen levels induced by RIRI. Both HE and PAS staining of kidney tissues revealed that GW3965 alleviated the morphological damages caused by RIRI. Immunohistochemical staining showed that GW3965 mitigated 4-HNE and GRP78 levels induced by RIRI. Furthermore, TUNEL assay indicated that GW3965 reduced RIRI-induced renal cell apoptosis. Quantitative real-time PCR (qPCR) analysis revealed that GW3965 attenuated RIRIinduced IL-6 and IL-1β mRNA expression. Compared with wild-type group, LXRα gene deficiency had little effect on RIRIassociated renal functional decline and morphological damages. Additionally, in vitro study demonstrated that GW3965 alleviated H/ R-induced decrease of HK-2 human renal proximal tubule cell viability and restored the activity of superoxide dismutase (SOD) after H/R. Western blot results showed that GW3965 mitigated the increase of 4-HNE and GRP78 protein expression levels after H/R; However, knockdown of LXRβ using the small interfering RNA (siRNA) technique reduced cell viability compared to GW3965- treated group. Taken together, the LXRs agonist GW3965 significantly alleviates RIRI in mice possibly by reducing apoptosis, oxidative stress, endoplasmic reticulum stress and inflammation. These results also preliminarily confirm that the renal protective effects of LXRs agonists are dependent on LXRβ.

Key words: acute renal injury; ischemia-reperfusion; liver X receptor; GW3965

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通讯作者：张晓燕　　E-mail:

引用本文：

黄英枝, 栾志琳, 刘舒静, 张聪, 明文华, 任保印, 管又飞, 张晓燕. 肝X受体减轻肾脏缺血/再灌注损伤[J]. 生理学报 2024; 76 (6): 927-936.

HUANG Ying-Zhi, LUAN Zhi-Lin, LIU Shu-Jing, ZHANG Cong, MING Wen-Hua, REN Bao-Yin, GUAN You-Fei, ZHANG Xiao-Yan. Liver X receptor attenuates renal ischemia-reperfusion injury in mice. Acta Physiol Sin 2024; 76 (6): 927-936 (in Chinese with English abstract).