School of Molecular Biosciences, College of Veterinary Medicine, Washington State University, Pullman, Washington, USA.
Paul G. Allen School for Global Health, College of Veterinary Medicine, Washington State University, Pullman, Washington, USA.
Infect Immun. 2024 Jul 11;92(7):e0005324. doi: 10.1128/iai.00053-24. Epub 2024 Jun 5.
is an obligate intracellular bacteria that causes the global zoonotic disease Q Fever. Treatment options for chronic infection are limited, and the development of novel therapeutic strategies requires a greater understanding of how interacts with immune signaling. Cell death responses are known to be manipulated by , but the role of caspase-8, a central regulator of multiple cell death pathways, has not been investigated. In this research, we studied bacterial manipulation of caspase-8 signaling and the significance of caspase-8 to infection, examining bacterial replication, cell death induction, and cytokine signaling. We measured caspase, RIPK, and MLKL activation in -infected tumor necrosis factor alpha (TNFα)/cycloheximide-treated THP-1 macrophage-like cells and TNFα/ZVAD-treated L929 cells to assess apoptosis and necroptosis signaling. Additionally, we measured replication, cell death, and TNFα induction over 12 days in RIPK1-kinase-dead, RIPK3-kinase-dead, or RIPK3-kinase-dead-caspase-8 bone marrow-derived macrophages (BMDMs) to understand the significance of caspase-8 and RIPK1/3 during infection. We found that caspase-8 is inhibited by , coinciding with inhibition of apoptosis and increased susceptibility to necroptosis. Furthermore, replication was increased in BMDMs lacking caspase-8, but not in those lacking RIPK1/3 kinase activity, corresponding with decreased TNFα production and reduced cell death. As TNFα is associated with the control of , this lack of a TNFα response may allow for the unchecked bacterial growth we saw in caspase-8 BMDMs. This research identifies and explores caspase-8 as a key regulator of infection, opening novel therapeutic doors.
是一种专性细胞内细菌，可引起全球人畜共患疾病 Q 热。慢性感染的治疗选择有限，开发新的治疗策略需要更好地了解如何与免疫信号相互作用。已知细胞死亡反应会受到的操纵，但中央调节多种细胞死亡途径的胱天蛋白酶-8 的作用尚未得到研究。在这项研究中，我们研究了细菌对胱天蛋白酶-8 信号的操纵以及胱天蛋白酶-8 对感染的重要性，检查了细菌复制、细胞死亡诱导和细胞因子信号。我们测量了肿瘤坏死因子 α (TNFα)/环磷酰胺处理的 THP-1 巨噬样细胞和 TNFα/ZVAD 处理的 L929 细胞中感染的胱天蛋白酶、RIPK 和 MLKL 的激活，以评估细胞凋亡和坏死信号。此外，我们在 RIPK1 激酶缺陷型、RIPK3 激酶缺陷型或 RIPK3 激酶缺陷型-胱天蛋白酶-8 骨髓来源巨噬细胞 (BMDM) 中测量了 12 天内的复制、细胞死亡和 TNFα 诱导，以了解感染过程中胱天蛋白酶-8 和 RIPK1/3 的重要性。我们发现胱天蛋白酶-8 被抑制，同时抑制细胞凋亡并增加对坏死的易感性。此外，在缺乏胱天蛋白酶-8 的 BMDM 中，而不是在缺乏 RIPK1/3 激酶活性的 BMDM 中，复制增加，与 TNFα 产生减少和细胞死亡减少相对应。由于 TNFα 与的控制有关，这种缺乏 TNFα 反应可能允许我们在胱天蛋白酶-8 BMDM 中看到的不受控制的细菌生长。这项研究确定并探讨了胱天蛋白酶-8 作为感染的关键调节剂，为新的治疗方法开辟了新的途径。
