Division of Anesthesiology, Critical Care & Pain Medicine, Department of Critical Care, University of Texas MD Anderson Cancer Center, Houston, TX.
Developmental Dentistry, UT Health Science Center at San Antonio, San Antonio, TX.
Immunohorizons. 2024 Aug 1;8(8):586-597. doi: 10.4049/immunohorizons.2400058.
Neutrophil extracellular traps (NETs) function to control infectious agents as well as to propagate inflammatory response in a variety of disease conditions. DNA damage associated with chromatin decondensation and NACHT domain-leucine-rich repeat-and pyrin domain-containing protein 3 (NLRP3) inflammasome activation have emerged as crucial events in NET formation, but the link between the two processes is unknown. In this study, we demonstrate that poly(ADP-ribose) polymerase-1 (PARP-1), a key DNA repair enzyme, regulates NET formation triggered by NLRP3 inflammasome activation in neutrophils. Activation of mouse neutrophils with canonical NLRP3 stimulants LPS and nigericin induced NET formation, which was significantly abrogated by pharmacological inhibition of PARP-1. We found that PARP-1 is required for NLRP3 inflammasome assembly by regulating post-transcriptional levels of NLRP3 and ASC dimerization. Importantly, this PARP-1-regulated NLRP3 activation for NET formation was independent of inflammasome-mediated pyroptosis, because caspase-1 and gasdermin D processing as well as IL-1β transcription and secretion remained intact upon PARP-1 inhibition in neutrophils. Accordingly, pharmacological inhibition or genetic ablation of caspase-1 and gasdermin D had no effect on NLRP3-mediated NET formation. Mechanistically, PARP-1 inhibition increased p38 MAPK activity, which was required for downmodulation of NLRP3 and NETs, because concomitant inhibition of p38 MAPK with PARP-1 restored NLRP3 activation and NET formation. Finally, mice undergoing bacterial peritonitis exhibited increased survival upon treatment with PARP-1 inhibitor, which correlated with increased leukocyte influx and improved intracellular bacterial clearance. Our findings reveal a noncanonical pyroptosis-independent role of NLRP3 in NET formation regulated by PARP-1 via p38 MAPK, which can be targeted to control NETosis in inflammatory diseases.
中性粒细胞胞外诱捕网 (NETs) 的功能是控制感染因子，并在多种疾病状态下引发炎症反应。与染色质解凝聚和 NACHT 结构域富含亮氨酸重复和吡喃结构域蛋白 3 (NLRP3) 炎性小体激活相关的 DNA 损伤已成为 NET 形成的关键事件，但这两个过程之间的联系尚不清楚。在这项研究中，我们证明了多聚（ADP-核糖）聚合酶-1 (PARP-1)，一种关键的 DNA 修复酶，调节中性粒细胞中 NLRP3 炎性小体激活引发的 NET 形成。用经典的 NLRP3 刺激物 LPS 和 Nigericin 激活小鼠中性粒细胞会诱导 NET 形成，而 PARP-1 的药理学抑制则显著阻断了这一过程。我们发现，PARP-1 通过调节 NLRP3 和 ASC 二聚体的转录后水平，从而调节 NLRP3 炎性小体的组装。重要的是，这种 PARP-1 调节的 NLRP3 激活对于 NET 的形成是独立于炎性小体介导的细胞焦亡的，因为在中性粒细胞中抑制 PARP-1 后，caspase-1 和 gasdermin D 的加工以及 IL-1β 的转录和分泌仍然完整。因此，caspase-1 和 gasdermin D 的药理学抑制或基因敲除对 NLRP3 介导的 NET 形成没有影响。在机制上，PARP-1 抑制增加了 p38 MAPK 的活性，这对于下调 NLRP3 和 NET 是必需的，因为同时抑制 p38 MAPK 和 PARP-1 恢复了 NLRP3 的激活和 NET 的形成。最后，在患有细菌性腹膜炎的小鼠中，用 PARP-1 抑制剂治疗后，存活时间延长，这与白细胞流入增加和细胞内细菌清除率提高有关。我们的研究结果揭示了 NLRP3 在 NET 形成中的一种非典型的细胞焦亡非依赖性作用，该作用通过 p38 MAPK 被 PARP-1 调节，这一机制可以作为控制炎症性疾病中 NETosis 的靶点。
