Background: The nucleotide-binding and oligomerization domain-like receptor protein 3 (NLRP3) inflammasome composed of NLRP3, apoptosis-associated speck-like protein containing CARD (ASC), and caspase-1 is engaged in the inflammatory response of many kidney diseases and can be activated by purinergic 2X7 receptor (P2X7R). This study was conducted to explore whether P2X7R plays a pathogenic role in the podocyte damage of obesity-related glomerulopathy (ORG) and whether this role is mediated by the activation of NLRP3 inflammasome.
Methods: A mouse model of ORG was established by high-fat diet feeding. The conditionally immortalized mouse podocytes were cultured with leptin or with leptin and P2X7R antagonist (KN-62 or A438079). The mRNA and protein expression of the P2X7R and NLRP3 inflammasome components including NLRP3, ASC, and caspase-1, as well as the podocyte-associated molecules including nephrin, podocin, and desmin in mouse renal cortex or cultured mouse podocytes were tested by real-time-polymerase chain reaction and Western blot analysis, respectively.
Results: The significantly upregulated expression of P2X7R and NLRP3 inflammasome components and the NLRP3 inflammasome activation were observed in the renal cortex (in fact their location in podocytes was proved by confocal microscopy) of ORG mice in vivo, which were accompanied with the morphological changes of podocyte damage and the expression changes of podocyte-associated molecules. Similar changes in the expression of P2X7R and NLRP3 inflammasome components as well as in the expression of podocyte-associated molecules were also observed in the cultured podocyte studies treated by leptin in vitro, and all of the above changes were significantly attenuated by the P2X7R antagonist KN-62 or A438079.
Conclusions: P2X7R could trigger the activation of NLRP3 inflammasome, and the activated P2X7R/NLRP3 inflammasome in podocytes might be involved in the podocyte damage of ORG.
P2X7R通过活化NLRP3炎症体参与肥胖相关性肾小球病的足细胞损伤 摘要 背景：由NOD-样受体蛋白3（NLRP3）、凋亡相关斑点样蛋白（ASC）和半胱氨酸天冬氨酸酶-1（caspase-1）组成的NLRP3炎症体参与了许多肾脏病的炎症反应，且此炎症体能被嘌呤能2X7受体（P2X7R）激活。本研究拟探讨P2X7R是否参与了肥胖相关性肾小球病（ORG）的足细胞损伤，且此作用是否通过NLRP3炎症体介导。 方法：用高脂饲料喂养小鼠制作ORG模型进行整体体内研究，并用瘦素刺激培养的条件性永生小鼠足细胞进行体外研究。P2X7R和NLRP3炎症体各组份（NLRP3、ASC和caspase-1）及足细胞相关分子（nephrin、podocin和结蛋白）的mRNA及蛋白质表达分别用实时半定量PCR及Western印迹法进行检测。 结果：ORG小鼠整体研究显示，小鼠肾皮质中（共聚焦显微镜检查显示实际在足细胞中）的P2X7R和NLRP3炎症体各组份表达显著上调，NLRP3炎症体活化，且伴随出现了小鼠足细胞损伤（包括形态学表现及足细胞相关分子表达改变）。用瘦素刺激的足细胞体外研究，也发现了与上相似的P2X7R和NLRP3炎症体表达上调/活化，和足细胞相关分子表达的改变，而上述所有变化均能被P2X7R拮抗剂KN-62或 A438079拮抗。 结论：P2X7R能激活NLRP3炎症体，ORG时足细胞中P2X7R和NLRP3炎症体的激活能参与足细胞损伤。.
Keywords: Desmin; Nucleotide-Binding and Oligomerization Domain-Like Receptor Protein 3 Inflammasome; Obesity-Related Glomerulopathy; Podocytes; Purinergic 2X7 Receptor.