Acute inflammatory responses often involve the production of reactive oxygen and nitrogen species by innate immune cells, particularly macrophages. How activated macrophages protect themselves in the face of oxidative-inflammatory stress remains a long-standing question. Recent evidence implicates reactive sulfur species (RSS) in inflammatory responses; however, how endogenous RSS affect macrophage function and response to oxidative and inflammatory insults remains poorly understood. In this study, we investigated the endogenous pathways of RSS biogenesis and clearance in macrophages, with a particular focus on exploring how hydrogen sulfide (HS)-mediated -persulfidation influences macrophage responses to oxidative-inflammatory stress. We show that classical activation of mouse or human macrophages using lipopolysaccharide and interferon-γ (LPS/IFN-γ) triggers substantial production of HS/RSS, leading to widespread protein persulfidation. Biochemical and proteomic analyses revealed that this surge in cellular -persulfidation engaged ∼2% of total thiols and modified over 800 functionally diverse proteins. -persulfidation was found to be largely dependent on the cystine importer xCT and the HS-generating enzyme cystathionine γ-lyase and was independent of changes in the global proteome. We further investigated the role of the sulfide-oxidizing enzyme sulfide quinone oxidoreductase (SQOR), and found that it acts as a negative regulator of -persulfidation. Elevated -persulfidation following LPS/IFN-γ stimulation or SQOR inhibition was associated with increased resistance to oxidative stress. Upregulation of persulfides also inhibited the activation of the macrophage NLRP3 inflammasome and provided protection against inflammatory cell death. Collectively, our findings shed light on the metabolism and effects of RSS in macrophages and highlight the crucial role of persulfides in enabling macrophages to withstand and alleviate oxidative-inflammatory stress.

中文翻译：

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活化巨噬细胞中广泛存在的 S-过硫化作为对抗氧化炎症应激的保护机制

急性炎症反应通常涉及先天免疫细胞（特别是巨噬细胞）产生活性氧和氮。活化的巨噬细胞在面对氧化炎症应激时如何保护自己仍然是一个长期存在的问题。最近的证据表明活性硫物质 (RSS) 与炎症反应有关；然而，内源性RSS如何影响巨噬细胞功能以及对氧化和炎症损伤的反应仍知之甚少。在这项研究中，我们研究了巨噬细胞中 RSS 生物发生和清除的内源性途径，特别关注探索硫化氢 (HS) 介导的过硫化如何影响巨噬细胞对氧化炎症应激的反应。我们发现，使用脂多糖和干扰素-γ (LPS/IFN-γ) 经典激活小鼠或人类巨噬细胞会引发 HS/RSS 的大量产生，从而导致广泛的蛋白质过硫化。生化和蛋白质组学分析表明，细胞过硫化作用的激增涉及约 2% 的总硫醇，并修饰了 800 多种功能多样的蛋白质。 -发现过硫化很大程度上依赖于胱氨酸输入蛋白xCT和HS生成酶胱硫醚γ-裂解酶，并且与整体蛋白质组的变化无关。我们进一步研究了硫化物氧化酶硫化物醌氧化还原酶（SQOR）的作用，发现它作为β-过硫化的负调节剂。 LPS/IFN-γ刺激或SQOR抑制后β-过硫化升高与氧化应激抵抗力增强相关。过硫化物的上调还抑制巨噬细胞 NLRP3 炎症小体的激活，并提供针对炎症细胞死亡的保护。总的来说，我们的研究结果揭示了巨噬细胞中 RSS 的代谢和影响，并强调了过硫化物在使巨噬细胞能够承受和减轻氧化炎症应激方面的关键作用。