Department of Physiology and Pathophysiology, School of Basic Medical Sciences, Fudan University, Shanghai, 200032, China.
Department of Nephrology, Shanghai Tong Ren Hospital, Shanghai Jiao Tong University School of Medicine, Shanghai, 200336, China.
Acta Pharmacol Sin. 2022 Jan;43(1):86-95. doi: 10.1038/s41401-021-00619-2. Epub 2021 Mar 23.
Ischemia/reperfusion (I/R) injury is a major cause of acute kidney injury (AKI) in clinic. The activation of NLRP3 inflammasome is associated with inflammation and renal injury in I/R-induced AKI. In the current study we explored the molecular and cellular mechanisms for NLRP3 inflammasome activation following renal I/R. Mice were subjected to I/R renal injury by clamping bilateral renal pedicles. We showed that I/R injury markedly increased caspase-11 expression and the cleavage of pannexin 1 (panx1) in the kidneys accompanied by NLRP3 inflammasome activation evidenced by the activation of caspase-1 and interlukin-1β (IL-1β) maturation. In Casp-11 mice, I/R-induced panx1 cleavage, NLRP3 inflammasome activation as well as renal functional deterioration and tubular morphological changes were significantly attenuated. In cultured primary tubular cells (PTCs) and NRK-52E cells, hypoxia/reoxygenation (H/R) markedly increased caspase-11 expression, NLRP3 inflammasome activation, IL-1β maturation and panx1 cleavage. Knockdown of caspase-11 attenuated all those changes; similar effects were observed in PTCs isolated from Casp-11 mice. In NRK-52E cells, overexpression of caspase-11 promoted panx1 cleavage; pretreatment with panx1 inhibitor carbenoxolone or knockdown of panx1 significantly attenuated H/R-induced intracellular ATP reduction, extracellular ATP elevation and NLRP3 inflammasome activation without apparent influence on H/R-induced caspase-11 increase; pretreatment with P2X7 receptor inhibitor AZD9056 also attenuated NLRP3 inflammasome activation. The above results demonstrate that the cleavage of panx1 by upregulated caspase-11 is involved in facilitating ATP release and then NLRP3 inflammasome activation in I/R-induced AKI. This study provides new insight into the molecular mechanism of NLRP3 inflammasome activation in AKI.
缺血/再灌注（I/R）损伤是临床急性肾损伤（AKI）的主要原因。NLRP3 炎性小体的激活与 I/R 诱导的 AKI 中的炎症和肾损伤有关。在本研究中，我们探讨了 NLRP3 炎性小体激活后肾 I/R 的分子和细胞机制。通过夹闭双侧肾蒂，使小鼠发生肾 I/R 损伤。我们发现，I/R 损伤明显增加了肾脏中 caspase-11 的表达和孔蛋白 1（panx1）的切割，同时伴随着 NLRP3 炎性小体的激活，表现为 caspase-1 和白细胞介素-1β（IL-1β）的成熟。在 Casp-11 小鼠中，I/R 诱导的 panx1 切割、NLRP3 炎性小体的激活以及肾功能恶化和肾小管形态变化明显减弱。在原代肾小管细胞（PTCs）和 NRK-52E 细胞中，缺氧/复氧（H/R）明显增加了 caspase-11 的表达、NLRP3 炎性小体的激活、IL-1β 的成熟和 panx1 的切割。Caspase-11 的敲低减弱了所有这些变化；在 Casp-11 小鼠分离的 PTCs 中也观察到类似的影响。在 NRK-52E 细胞中，caspase-11 的过表达促进了 panx1 的切割；panx1 抑制剂 carbenoxolone 的预处理或 panx1 的敲低显著减弱了 H/R 诱导的细胞内 ATP 减少、细胞外 ATP 升高和 NLRP3 炎性小体的激活，而对 H/R 诱导的 caspase-11 增加没有明显影响；P2X7 受体抑制剂 AZD9056 的预处理也减弱了 NLRP3 炎性小体的激活。上述结果表明，上调的 caspase-11 对 panx1 的切割参与了 I/R 诱导的 AKI 中 ATP 的释放，进而促进 NLRP3 炎性小体的激活。本研究为 AKI 中 NLRP3 炎性小体激活的分子机制提供了新的见解。
