肌萎缩性侧索硬化蛋白激活小胶质细胞NLRP3炎性小体

小胶质细胞NLRP3炎性小体激活正在成为神经退行性变过程中神经炎症的关键因素。诸如β-淀粉样蛋白和α-突触核蛋白之类的致病性蛋白质聚集体触发小胶质NLRP3激活,从而导致半胱天冬酶-1激活和IL-1β的分泌。在小鼠肌萎缩性侧索硬化症(ALS)的SOD1G93A模型中,半胱天冬酶-1和IL-1β均促进疾病进展,提示小胶质NLRP3在该进程中发挥作用。然而先前的研究表明,SOD1G93A小鼠小胶质细胞不表达NLRP3,SOD1G93A蛋白在小胶质细胞中产生独立于NLRP3的IL-1β。本研究论证了使用Nlrp3-GFP基因敲入小鼠,在SOD1G93A小鼠中小胶质细胞表达NLRP3。本研究显示聚集和可溶性SOD1G93A均可激活小鼠原代小胶质细胞中的炎性小体,导致半胱天冬酶-1和IL-1β裂解,ASC斑点形成以及呈剂量和时间依赖性的IL-1β分泌。重要的是,SOD1G93A无法从缺乏Nlrp3的小胶质细胞或者用特异性NLRP3抑制剂MCC950预处理的小胶质细胞中诱导IL-1β分泌,从而证实NLRP3是介导SOD1诱导的小胶质细胞IL-1β分泌的关键炎症小体复合物。在TDP-43Q331K ALS小鼠模型中也观察到小胶质NLRP3上调,TDP-43野生型和突变蛋白亦可以NLRP3依赖性的方式激活小胶质炎性小体。从机制上讲,本研究确定了活性氧簇和ATP的生成是SOD1G93A介导的NLRP3激活所需的关键事件。总之,本研究的数据表明ALS小胶质细胞表达NLRP3,而病理ALS蛋白激活小胶质NLRP3炎性小体。因此,NLRP3抑制可能是阻止小胶质细胞神经炎症和ALS疾病进展的潜在治疗方法。

肌萎缩侧索硬化蛋白激活小胶质细胞NLRP3炎性体

小胶质细胞NLRP3炎症小体激活正在成为神经退行性变期间神经炎症的关键因素。β-淀粉样蛋白和α-突触核蛋白等致病蛋白的聚集体可触发小胶质细胞NLRP3激活,并导致半胱氨酸天冬氨酸酶激活和白介素-1β分泌。半胱氨酸天冬氨酸酶和白介素-1β均促进肌萎缩侧索硬化(ALS)小鼠SOD1G93A模型的疾病进展,这提示小胶质细胞NLRP3在该进程中起作用。然而,先前的研究表明SOD1G93A模型小鼠的小胶质细胞并不表达NLRP3,并且SOD1G93A蛋白在小胶质细胞中产生白介素-1β不依赖于NLRP3。本研究展示了使用Nlrp3-GFP基因敲入小鼠,在SOD1G93A小鼠中小胶质细胞表达NLRP3。结果表明,聚集和可溶性SOD1G93A均以剂量和时间依赖性方式激活小鼠原代小胶质细胞中的炎性体,导致半胱氨酸天冬氨酸酶和白介素-1β裂解、ASC斑点形成和白介素-1β分泌。重要的是,SOD1G93A不能诱导缺乏Nlrp3的小胶质细胞或用特异性NLRP3抑制剂MCC950预处理的小胶质细胞分泌白介素-1β,这证实NLRP3是介导SOD1诱导的小胶质细胞白介素-1β分泌的关键炎性体复合物。在TDP-43Q331K ALS小鼠模型中也观察到小胶质细胞NLRP3上调,并且TDP-43野生型和突变蛋白也能以NLRP3依赖性方式激活小胶质细胞炎症小体。从机制上,本研究确定活性氧簇和ATP的产生是SOD1G93A介导的NLRP3激活所需的关键事件。总之,本研究的数据表明ALS小胶质细胞表达NLRP3,病理性ALS蛋白激活了小胶质细胞NLRP3炎性体。因此,抑制NLRP3可能是阻止小胶质细胞神经炎症和ALS疾病进展的潜在治疗方法。

Sterile signals generate weaker and delayed macrophage NLRP3 inflammasome responses relative to microbial signals

Inflammation is the host response to microbial infection or sterile injury that aims to eliminate the insult, repair the tissue and restore homeostasis. Macrophages and the NLRP3 inflammasome are key sentinels for both types of insult. Although it is well established that the NLRP3 inflammasome is activated by microbial products and molecules released during sterile injury, it is unclear whether the responses elicited by these different types of signals are distinct. In this study, we used lipopolysaccharide and tumor necrosis factor as prototypical microbial and sterile signal 1 stimuli, respectively, to prime the NLRP3 inflammasome. We then used the bacterial toxin nigericin and a common product released from necrotic cells, ATP, as prototypical microbial and sterile signal 2 stimuli, respectively, to trigger the assembly of the NLRP3 inflammasome complex in mouse and human macrophages. We found that NLRP3 inflammasome responses were weakest when both signal 1 and signal 2 were sterile, but responses were faster and stronger when at least one of the two signals was microbial. Ultimately, the most rapid and potent responses were elicited when both signals were microbial. Together, these data suggest that microbial versus sterile signals are distinct, both kinetically and in magnitude, in their ability to generate inflammasome-dependent responses. This hierarchy of NLRP3 responses to sterile versus microbial stimuli likely reflects the urgent need for the immune system to respond rapidly to the presence of infection to halt pathogen dissemination.