Centre for Innate Immunity and Infectious Diseases, Hudson Institute of Medical Research, Clayton, VIC, Australia.
Department of Molecular and Translational Science, Monash University, Clayton, VIC, Australia.
EMBO Rep. 2023 Nov 6;24(11):e56865. doi: 10.15252/embr.202356865. Epub 2023 Oct 17.
Programmed cell death pathways play an important role in innate immune responses to infection. Activation of intrinsic apoptosis promotes infected cell clearance; however, comparatively little is known about how this mode of cell death is regulated during infections and whether it can induce inflammation. Here, we identify that the pro-survival BCL-2 family member, A1, controls activation of the essential intrinsic apoptotic effectors BAX/BAK in macrophages and monocytes following bacterial lipopolysaccharide (LPS) sensing. We show that, due to its tight transcriptional and post-translational regulation, A1 acts as a molecular rheostat to regulate BAX/BAK-dependent apoptosis and the subsequent NLRP3 inflammasome-dependent and inflammasome-independent maturation of the inflammatory cytokine IL-1β. Furthermore, induction of A1 expression in inflammatory monocytes limits cell death modalities and IL-1β activation triggered by Neisseria gonorrhoeae-derived outer membrane vesicles (NOMVs). Consequently, A1-deficient mice exhibit heightened IL-1β production in response to NOMV injection. These findings reveal that bacteria can induce A1 expression to delay myeloid cell death and inflammatory responses, which has implications for the development of host-directed antimicrobial therapeutics.
程序性细胞死亡途径在感染的固有免疫反应中发挥重要作用。内在细胞凋亡的激活促进受感染细胞的清除;然而,关于这种细胞死亡模式如何在感染过程中被调控以及它是否能引发炎症,人们知之甚少。在这里,我们发现,在细菌脂多糖 (LPS) 感应后,存活的 BCL-2 家族成员 A1 控制着巨噬细胞和单核细胞中必需的内在凋亡效应因子 BAX/BAK 的激活。我们表明,由于其严格的转录和翻译后调控,A1 作为分子变阻器,调节 BAX/BAK 依赖性凋亡以及随后 NLRP3 炎性小体依赖性和非依赖性成熟的炎症细胞因子 IL-1β。此外,在炎症性单核细胞中诱导 A1 表达,限制了由淋病奈瑟菌衍生的外膜囊泡 (NOMVs) 触发的细胞死亡方式和 IL-1β 的激活。因此,A1 缺陷小鼠对 NOMV 注射的反应表现出更高的 IL-1β 产生。这些发现表明,细菌可以诱导 A1 表达来延迟髓样细胞死亡和炎症反应,这对开发宿主导向的抗菌治疗具有重要意义。