Anthrax lethal toxin-induced inflammasome formation and caspase-1 activation are late events dependent on ion fluxes and the proteasome
Anthrax lethal toxin-induced inflammasome formation and caspase-1 activation are late events dependent on ion fluxes and the proteasome
复制标题
DOI：
10.1111/j.1462-5822.2007.01044.x
复制
发表时间：
2008-02-01
影响因子：
3.4
通讯作者：
Moayeri, Mahtab
中科院分区：
文献类型：
--
作者：
Wickliffe, Katherine E.;Leppla, Stephen H.;Moayeri, Mahtab
炭疽致死毒素 (LT) 对某些近交系小鼠的巨噬细胞具有细胞毒性。控制巨噬细胞对 LT 敏感性的基因是 Nalp1b。 Nalp1b 形成炎症小体的一部分，炎症小体是一种多蛋白复合物，参与 caspase-1 激活和白细胞介素 (IL)-1 beta 和 IL-18 的释放。我们证实了 caspase-1 在 LT 介导的死亡中的作用，通过证明 caspase 抑制剂对细胞提供不同的 LT 保护，保护程度与每种化合物抑制 caspase-1 的能力相对应。 Caspase-1 激活和细胞因子加工和释放是晚期事件，可被 KCl 和蔗糖水平升高、钾通道阻滞剂和蛋白酶体抑制剂抑制，这表明炎症小体的形成需要蛋白质降解事件，并发生在 LT 介导的钾流出的下游。此外，IL-18 和 IL-1 β 的释放依赖于细胞死亡，表明 caspase-1 介导的细胞毒性独立于这些细胞因子。最后，在 LT 抗性巨噬细胞中诱导 NALP3 炎性体形成并不会使细胞对 LT 敏感，这表明一般 caspase-1 激活不能解释对 LT 的敏感性，并且 Nalp1b 介导的事件是死亡所特别需要的。我们的数据表明，炎症小体的形成是 LT 介导的细胞毒性的一个贡献事件，但不是起始事件，并且早期的 LT 介导事件导致离子通量是死亡所必需的。
Anthrax lethal toxin (LT) is cytotoxic to macrophages from certain inbred mouse strains. The gene controlling macrophage susceptibility to LT is Nalp1b. Nalp1b forms part of the inflammasome, a multiprotein complex involved in caspase-1 activation and release of interleukin (IL)-1 beta and IL-18. We confirm the role of caspase-1 in LT-mediated death by showing that caspase inhibitors differentially protected cells against LT, with the degree of protection corresponding to each compound's ability to inhibit caspase-1. Caspase-1 activation and cytokine processing and release were late events inhibited by elevated levels of KCl and sucrose, by potassium channel blockers, and by proteasome inhibitors, suggesting that inflammasome formation requires a protein-degradation event and occurs downstream of LT-mediated potassium efflux. In addition, IL-18 and IL-1 beta release was dependent on cell death, indicating that caspase-1-mediated cytotoxicity is independent of these cytokines. Finally, inducing NALP3-inflammasome formation in LT-resistant macrophages did not sensitize cells to LT, suggesting that general caspase-1 activation cannot account for sensitivity to LT and that a Nalp1b-mediated event is specifically required for death. Our data indicate that inflammasome formation is a contributing, but not initiating, event in LT-mediated cytotoxicity and that earlier LT-mediated events leading to ion fluxes are required for death.