Divison of Molecular Signaling, Department of the Advanced Biomedical Research, Interdisciplinary Graduate School of Medicine, University of Yamanashi, Chuo, Japan.
Department of Molecular Pathology, Interdisciplinary Graduate School of Medicine, University of Yamanashi, Chuo, Japan.
Antioxid Redox Signal. 2019 Dec 1;31(16):1194-1212. doi: 10.1089/ars.2018.7636. Epub 2019 Aug 20.
Inflammasome activation plays a pivotal role in many inflammatory diseases. Given that connexin (Cx) channels regulate numerous cellular events leading to inflammasome activation, we determined whether and how connexin affected inflammasome activation and inflammatory cell injury. Exposure of mouse peritoneal macrophages (PMs) to lipopolysaccharide (LPS) plus ATP caused NLRP3 inflammasome activation, together with an increased connexin43 (Cx43). Inhibition of Cx43 blunted inflammasome activation. Consistently, PMs from the Cx43 heterozygous mouse (Cx43) exhibited weak inflammasome activation, in comparison with those from the Cx43 mouse. Further analysis revealed that inflammasome activation was preceded by an increased reactive oxygen species (ROS) production, nicotinamide adenine dinucleotide phosphate hydrogen (NADPH) oxidase 2 (NOX2), protein carbonylation, and mitogen-activated protein kinase (MAPK) activation. Suppression of ROS with antioxidant, downregulation of NOX2 with small interfering RNA (siRNA), or inhibition of NADPH oxidase or MAPKs with inhibitors blocked Cx43 elevation and inflammasome activation. Intriguingly, suppression of Cx43 also blunted NOX2 expression, protein carbonylation, p38 phosphorylation, and inflammasome activation. In a model of acute renal injury induced by LPS, the Cx43 mouse exhibited a significantly lower level of blood interleukin-1β (IL-1β), blood urea nitrogen, and urinary protein, together with milder renal pathological changes and renal expression of NLRP3 and NOX4, as compared with the Cx43 mouse. Moreover, inhibition of gap junctions suppressed IL-1β- and tumor necrosis factor-α-induced expression of NOX4 in glomerular podocytes and tubular epithelial cells. Our study indicates that Cx43 contributes to inflammasome activation and the progression of renal inflammatory cell injury through modulation of intracellular redox status. Cx43 could be a novel target for the treatment of certain inflammatory diseases.
炎性小体的激活在许多炎症性疾病中起着关键作用。鉴于连接蛋白 (Cx) 通道调节许多导致炎性小体激活的细胞事件，我们确定了连接蛋白是否以及如何影响炎性小体的激活和炎症细胞损伤。 脂多糖 (LPS) 加 ATP 暴露于小鼠腹腔巨噬细胞 (PM) 导致 NLRP3 炎性小体激活，同时增加了连接蛋白 43 (Cx43)。Cx43 抑制减弱了炎性小体的激活。一致地，与 Cx43 小鼠相比，Cx43 杂合子小鼠 (Cx43) 的 PM 表现出较弱的炎性小体激活。进一步分析表明，炎性小体的激活之前伴随着活性氧 (ROS) 产生、烟酰胺腺嘌呤二核苷酸磷酸氢 (NADPH) 氧化酶 2 (NOX2)、蛋白质羰基化和丝裂原激活蛋白激酶 (MAPK) 的激活增加。抗氧化剂抑制 ROS、小干扰 RNA (siRNA) 下调 NOX2 或抑制剂抑制 NADPH 氧化酶或 MAPKs 阻断了 Cx43 的升高和炎性小体的激活。有趣的是，抑制 Cx43 也减弱了 NOX2 的表达、蛋白质羰基化、p38 磷酸化和炎性小体的激活。在 LPS 诱导的急性肾损伤模型中，与 Cx43 小鼠相比，Cx43 小鼠的血液白细胞介素 1β (IL-1β)、血尿素氮和尿蛋白水平明显较低，肾组织中 NLRP3 和 NOX4 的表达也较轻，肾组织中 NLRP3 和 NOX4 的表达也较轻。此外，间隙连接的抑制抑制了 IL-1β 和肿瘤坏死因子-α诱导的肾小球足细胞和肾小管上皮细胞中 NOX4 的表达。 我们的研究表明，Cx43 通过调节细胞内氧化还原状态促进炎性小体的激活和肾脏炎症细胞损伤的进展。Cx43 可能成为某些炎症性疾病治疗的新靶点。
