肾源性HMGB1介导的炎症反应在脓毒症AKI向CKD转化中的作用

Patients with acute kidney disease (AKI) had higher risks of developing chronic kidney disease (CKD) (pooled adjusted hazard ratio 8.8), and the pooled incidence 25.8/100 person-years. The renal inflammatory response plays an important role in the process of AKI to CKD, but the specific molecular mechanism is still unclear. Our team has demonstrated that the serum and urine HMGB1 levels were increased in septic AKI rats, lipopolysaccharide induced cultured podocytes to secrete HMGB1. Therefore, we hypothesizes that continuous HMGB1 secreted by podocytes and renal tubular epithelial cells, mediates renal inflammatory response, which promote chronic transition after septic AKI. This project intends to evaluate the role of HMGB1 in the process of transition from septic AKI to CKD. We will evaluate the secretion of HMGB1, inflammatory factor and the phenotypic changes of the renal cells, we will also evaluate the interaction between HMGB1 and RAGE, TLR4 or TLR2 in the CLP septic rat model and cultured and co-cultured renal cells (podocytes, renal tubular epithelial cells and renal interstitial fibroblasts) treated with plasmid or small hairpin RNA transfection. This study will help us to clarify the molecular mechanism of septic AKI to CKD, and to supply the prevention means.

AKI患者每年25.8%进展到CKD，其风险是不伴AKI人群的8.8倍。肾脏的炎症反应在AKI-CKD转变过程中起重要作用，但调节炎症反应的分子机制不明。我们前期研究发现脓毒症AKI大鼠血液、尿液HMGB1水平升高，脂多糖诱导足细胞分泌HMGB1。因此，本研究推测足细胞、肾小管上皮细胞持续分泌HMGB1介导肾脏炎症反应，诱导脓毒症AKI-CKD的转变。本项目拟采用CLP脓毒症大鼠模型，并以足细胞、肾小管上皮细胞、成纤维细胞系为研究对象，应用基因转染、细胞共培养等手段，观察细胞分泌的HMGB1、其他炎症因子及细胞表型的改变，明确HMGB1通过与RAGE、TLR4、TLR2等受体蛋白相互作用介导炎症反应，诱发肾间质纤维化，深入探讨肾源性HMGB1在脓毒症AKI-CKD转化过程中的作用。本项目的实施将有助于阐明脓毒症AKI慢性化转变的炎症机制，并为脓毒症AKI-CKD转变的防治提供新的思路。

部分急性肾损伤（AKI）患者会进展到慢性肾脏病（CKD），肾脏的炎症反应在AKI-CKD转变过程中起重要作用，但调节炎症反应的分子机制不明。本研究探讨高迁移率族蛋白1（HMGB1）对脓毒症及相关AKI诊断和预后评估的价值，HMGBl介导体外培养的肾小管上皮细胞功能的变化并探讨其机制；以及Sirt6在缺氧诱导肾小管上皮细胞损伤中的作用和机制。结果发现（1）脓毒症及相关AKI患者血、尿HMGB1均明显升高，血浆HMGB1对脓毒症病情严重程度有鉴别价值，尿HMGB1有助于诊断脓毒症AKI并评估严重脓毒症及脓毒症AKI患者的预后。（2）NRK52E细胞表达TLR4；与对照组比较，HMGBl刺激组细胞周期G1期阻滞率高，MAPK信号通路及NF-KB激活，IL-1、IL-6及TIMP2 mRNA及蛋白表达水平均显著升高(均P＜0.05)；TLR4特异性阻断剂LPS RS可以显著抑制HMGBl所介导的效应(均P＜0.05)。（3）缺血再灌注肾损伤小鼠肾脏Sirt6表达下调，缺氧诱导的肾小管上皮细胞Sirt6表达下调，肾小管上皮细胞过表达Sirt6后，低氧诱导的细胞损伤减轻，抑制细胞周期G2/M阻滞，敲低肾小管上皮细胞表达Sirt6后，低氧诱导的细胞损伤加重。本研究为部分阐明了脓毒症AKI及缺血再灌注AKI的分子机制，为脓毒症ALI的严重程度及预后判断提供了可能的分子标志物HMGB1，以及缺血再灌注肾损伤的预防提供了新的治疗靶点Sirt6。