Cytolethal distending toxins (Cdt) are a family of toxins produced by several human pathogens which infect mucocutaneous tissue and induce inflammatory disease. We have previously demonstrated that the Aggregatibacter actinomycetemcomitans Cdt induces a pro‐inflammatory response from human macrophages which involves activation of the NLRP3 inflammasome. We now demonstrate that in addition to activating caspase‐1 (canonical inflammasome), Cdt treatment leads to caspase‐4 activation and involvement of the noncanonical inflammasome. Cdt‐treated cells exhibit pyroptosis characterised by cleavage of gasdermin‐D (GSDMD), release of HMGB1 at 24 hr and LDH at 48 hr. Inhibition of either the canonical (caspase‐1) or noncanonical (caspase‐4) inflammasome blocks both Cdt‐induced release of IL‐1β and induction of pyroptosis. Analysis of upstream events indicates that Cdt induces Syk phosphorylation (activation); furthermore, blockade of Syk expression and inhibition of pSyk activity inhibit both Cdt‐induced cytokine release and pyroptosis. Finally, we demonstrate that increases in pSyk are dependent upon Cdt‐induced activation of GSK3β. These studies advance our understanding of Cdt function and provide new insight into the virulence potential of Cdt in mediating the pathogenesis of disease caused by Cdt‐producing organisms such as A. actinomycetemcomitans .

中文翻译：

---

人巨噬细胞的细胞致死性毒素诱导的白介素-1β释放取决于糖原合酶激酶3β，脾酪氨酸激酶（Syk）和非典型炎症小体的激活。

细胞致死性扩张性毒素（Cdt）是由几种人类病原体产生的一族毒素，这些病原体会感染粘膜皮肤组织并诱发炎症性疾病。先前我们已经证明了放线杆菌Cdt诱导人巨噬细胞的促炎反应，涉及激活NLRP3炎性小体。现在，我们证明，除了激活caspase-1（规范性炎症小体）之外，Cdt治疗还导致caspase-4的激活和非规范性炎症小体的参与。经过Cdt处理的细胞表现出热解作用，其特征是切割了gasdermin-D（GSDMD），24小时释放HMGB1，48小时释放LDH。规范性（caspase-1）或非规范性（caspase-4）炎性小体的抑制均可阻断Cdt诱导的IL-1β释放并诱导细胞凋亡。对上游事件的分析表明，Cdt诱导Syk磷酸化（激活）。此外，对Syk表达的阻断和对pSyk活性的抑制同时抑制了Cdt诱导的细胞因子释放和细胞凋亡。最后，我们证明pSyk的增加取决于Cdt诱导的GSK3β激活。这些研究提高了我们对Cdt功能的理解，并提供了对Cdt在介导Cdt产生生物引起的疾病发病机理中潜在毒性的新见解。A.放线菌。