The hemolytic activity of inhaled particles such as silica has been widely investigated in the past and represents a usual toxicological endpoint to characterize particle reactivity despite the fact that red blood cells (RBCs) are not involved in the pathogenesis of pulmonary inflammation or fibrosis caused by some inhaled particles. The inflammatory process induced by silica starts with the activation of the inflammasome, which leads to the release of mature IL-1β. One of the upstream mechanisms causing activation of the inflammasome is the labilization of the phagolysosomal membrane after particle phagocytosis. Considering RBC lysis as a model of membrane damage, we evaluated the relationship between hemolytic activity and inflammasome-dependent release of IL-1β for a panel of selected silica particles, in search of the toxicological significance of the hemolytic activity of an inhaled particle. Well-characterized silica particles, including four quartz samples and a vitreous silica, with different surface properties and hemolytic potential were tested for their capacity to induce inflammasome-dependent release of IL-1β in LPS-primed primary murine peritoneal macrophages by ELISA and Western blot analysis. The mechanisms of IL-1β maturation and release were clarified by using ASC-deficient cells and inhibitors of phagocytosis and cathepsin B. The silica samples induced dose-dependent hemolysis and IL-1β release of different amplitudes. A significant correlation between IL-1β release and hemolytic activity was evidenced (r = 0.827) by linear regression analysis. IL-1β release was completely abolished in ASC-deficient cells and reduced by inhibitors, confirming the involvement of the inflammasome and the requirement of phagocytosis and cathepsin B for activation. The same physico-chemical properties of silica particles which are relevant for the lysis of the RBC membrane also appear implicated in the labilization of the phagolysosome, leading to inflammasome activation and release of the pro-inflammatory cytokine IL-1β. These findings strengthen the relevance of the hemolysis assay to predict the pro-inflammatory activity of silica dusts.

中文翻译：

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为什么二氧化硅的溶血活性可以预测其促炎活性？

吸入颗粒（例如二氧化硅）的溶血活性在过去已被广泛研究，并且代表了表征颗粒反应性的常用毒理学终点，尽管红细胞 (RBC) 并不参与由某些物质引起的肺部炎症或纤维化的发病机制。吸入颗粒。二氧化硅诱导的炎症过程始于炎症小体的激活，导致成熟 IL-1β 的释放。引起炎症小体激活的上游机制之一是颗粒吞噬作用后吞噬溶酶体膜的不稳定。将红细胞裂解作为膜损伤的模型，我们评估了一组选定的二氧化硅颗粒的溶血活性与炎症小体依赖性 IL-1β 释放之间的关系，以寻找吸入颗粒溶血活性的毒理学意义。通过 ELISA 和蛋白质印迹测试了具有不同表面特性和溶血潜力的充分表征的二氧化硅颗粒（包括四种石英样品和玻璃状二氧化硅）在 LPS 引发的原代小鼠腹膜巨噬细胞中诱导炎症小体依赖性 IL-1β 释放的能力分析。通过使用 ASC 缺陷细胞以及吞噬作用抑制剂和组织蛋白酶 B 阐明了 IL-1β 成熟和释放的机制。二氧化硅样品诱导剂量依赖性溶血和不同幅度的 IL-1β 释放。线性回归分析证明 IL-1β 释放与溶血活性之间存在显着相关性 (r = 0.827)。IL-1β 的释放在 ASC 缺陷细胞中完全消失，并被抑制剂减少，证实了炎症小体的参与以及吞噬作用和组织蛋白酶 B 的激活需要。与红细胞膜裂解相关的二氧化硅颗粒的相同理化性质似乎也与吞噬溶酶体的不稳定有关，导致炎症小体激活并释放促炎细胞因子 IL-1β。这些发现增强了溶血测定在预测硅尘促炎活性方面的相关性。