Department of Anesthesiology, College of Physicians and Surgeons of Columbia University , New York, New York.
Department of Pathology, College of Physicians and Surgeons of Columbia University , New York, New York.
Am J Physiol Renal Physiol. 2018 Feb 1;314(2):F293-F305. doi: 10.1152/ajprenal.00364.2017. Epub 2017 Oct 11.
We previously demonstrated that renal tubular peptidylarginine deiminase-4 (PAD4) is induced after ischemia-reperfusion (IR) injury and this induction of PAD4 exacerbates ischemic acute kidney injury (AKI) by promoting renal tubular inflammation and neutrophil infiltration. However, the mechanisms of renal tubular PAD4 induction after IR remain unknown. Here, we tested the hypothesis that ATP, a proinflammatory danger-associated molecular pattern (DAMP) ligand released from necrotic cells after IR injury, induces renal tubular PAD4 and exacerbates ischemic AKI via P2 purinergic receptor activation. ATP as well as ATPγS (a nonmetabolizable ATP analog) induced PAD4 mRNA, protein, and activity in human and mouse renal proximal tubule cells. Supporting the hypothesis that ATP induces renal tubular PAD4 via P2X7 receptor activation, A804598 (a selective P2X7 receptor antagonist) blocked the ATP-mediated induction of renal tubular PAD4 whereas BzATP (a selective P2X7 receptor agonist) mimicked the effects of ATP by inducing renal tubular PAD4 expression and activity. Moreover, ATP-mediated calcium influx in renal proximal tubule cells was blocked by A804598 and was mimicked by BzATP. P2X7 activation by BzATP also induced PAD4 expression and activity in mouse kidney in vivo. Finally, supporting a critical role for PAD4 in P2X7-mediated exacerbation of renal injury, BzATP exacerbated ischemic AKI in PAD4 wild-type mice but not in PAD4-deficient mice. Taken together, our studies show that ATP induces renal tubular PAD4 via P2X7 receptor activation to exacerbate renal tubular inflammation and injury after IR.
我们之前的研究表明，缺血再灌注（IR）损伤后会诱导肾小管肽基精氨酸脱亚氨酶-4（PAD4），这种 PAD4 的诱导会通过促进肾小管炎症和中性粒细胞浸润，加重缺血性急性肾损伤（AKI）。然而，IR 后肾小管 PAD4 诱导的机制尚不清楚。在这里，我们验证了一个假设，即 IR 损伤后坏死细胞释放的一种促炎危险相关分子模式（DAMP）配体 ATP，通过 P2 嘌呤能受体激活诱导肾小管 PAD4，从而加重缺血性 AKI。ATP 及其非代谢型类似物 ATPγS 诱导人源和鼠源近端肾小管细胞 PAD4mRNA、蛋白和活性增加。A804598（一种选择性 P2X7 受体拮抗剂）抑制了 ATP 介导的肾小管 PAD4 诱导，这支持了 ATP 通过激活 P2X7 受体诱导肾小管 PAD4 的假设，而 BzATP（一种选择性 P2X7 受体激动剂）通过诱导肾小管 PAD4 表达和活性模拟了 ATP 的作用。此外，A804598 阻断了 ATP 诱导的近端肾小管细胞内钙离子内流，而 BzATP 则模拟了这一作用。BzATP 激活 P2X7 还诱导了体内鼠肾中 PAD4 的表达和活性。最后，支持 PAD4 在 P2X7 介导的肾损伤加重中的关键作用，BzATP 加重了 PAD4 野生型小鼠的缺血性 AKI，但在 PAD4 缺陷型小鼠中没有加重。综上所述，我们的研究表明，ATP 通过 P2X7 受体激活诱导肾小管 PAD4，从而加重 IR 后肾小管炎症和损伤。
