Sharma Bhesh Raj, Choudhury Sk Mohiuddin, Abdelaal Hadia M, Wang Yaqiu, Kanneganti Thirumala-Devi
Department of Immunology, St. Jude Children's Research Hospital, Memphis, TN, United States.
J Immunol. 2025 Apr 18. doi: 10.1093/jimmun/vkaf042.
Inflammasomes are multiprotein innate immune complexes formed in response to infections, tissue damage, or cellular stress that promote the maturation and release of IL-1β/IL-18 and are implicated in lytic cell death. The NLRP3 inflammasome is canonically activated by an initial priming event followed by an activation stimulus, leading to rapid cell death that occurs through caspase-1 (CASP1) and gasdermin D (GSDMD) activation, called pyroptosis. CASP1- and GSDMD-deficient cells are protected from the rapid LPS plus ATP-induced pyroptosis. However, innate immune responses physiologically occur over time, extending beyond minutes to hours and days. Therefore, in this study, we assessed lytic cell death beyond the early timepoints. While cells lacking the innate immune sensor NLRP3 were protected from cell death induced by the canonical NLRP3 trigger, LPS priming and ATP stimulation (LPS plus ATP), for extended time, CASP1- and GSDMD-deficient cells started to lyse in a time-dependent manner after 2 h. Nevertheless, robust IL-1β and IL-18 release was still dependent on CASP1 activation. These data suggested that NLRP3 engages an additional innate immune, lytic cell death pathway. Indeed, LPS plus ATP induced the activation of caspases and RIPKs associated with PANoptosis in WT cells, and cells deficient in PANoptosis machinery were protected from cell death for extended times. A PANoptosome complex containing NLRP3, ASC, CASP8, and RIPK3 was observed by microscopy in WT, as well as CASP1- or GSDMD-deficient, cells by 30 min post-stimulation. Overall, these findings highlight the central role of NLRP3 as a PANoptosome sensor. Given the physiological role of innate immune cell death, PANoptosis, in health and disease, our study emphasizes the importance of a comprehensive understanding of PANoptosomes, and their components, as therapeutic targets.
炎性小体是多蛋白天然免疫复合物,在响应感染、组织损伤或细胞应激时形成,可促进白细胞介素-1β/白细胞介素-18的成熟和释放,并与溶解性细胞死亡有关。NLRP3炎性小体通常由初始启动事件后接激活刺激而激活,导致通过半胱天冬酶-1(CASP1)和gasdermin D(GSDMD)激活而发生快速细胞死亡,称为细胞焦亡。缺乏CASP1和GSDMD的细胞可免受快速脂多糖加ATP诱导的细胞焦亡。然而,天然免疫反应在生理上会随着时间的推移而发生,持续时间超过数分钟至数小时甚至数天。因此,在本研究中,我们评估了早期时间点之后的溶解性细胞死亡。虽然缺乏天然免疫传感器NLRP3的细胞可免受经典NLRP3触发因素脂多糖启动和ATP刺激(脂多糖加ATP)诱导的细胞死亡,但在较长时间后,缺乏CASP1和GSDMD的细胞在2小时后开始以时间依赖性方式裂解。尽管如此,强大的白细胞介素-1β和白细胞介素-18释放仍依赖于CASP1激活。这些数据表明,NLRP3参与了另一条天然免疫溶解性细胞死亡途径。事实上,脂多糖加ATP诱导野生型细胞中与PANoptosis相关的半胱天冬酶和RIPKs激活,而缺乏PANoptosis机制的细胞在较长时间内可免受细胞死亡。通过显微镜观察,在野生型以及缺乏CASP1或GSDMD的细胞中,刺激后30分钟可观察到含有NLRP3、ASC、CASP8和RIPK3的PANoptosome复合物。总体而言,这些发现突出了NLRP3作为PANoptosome传感器的核心作用。鉴于天然免疫细胞死亡即PANoptosis在健康和疾病中的生理作用,我们的研究强调了全面了解PANoptosomes及其成分作为治疗靶点的重要性。
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