Center of Excellence for Poultry Science, University of Arkansas, Fayetteville, Arkansas.
Cell and Molecular Biology Program, University of Arkansas, Fayetteville, Arkansas.
Am J Pathol. 2019 Oct;189(10):2077-2089. doi: 10.1016/j.ajpath.2019.06.013. Epub 2019 Aug 2.
Osteomyelitis remains a serious inflammatory bone disease that affects millions of individuals worldwide and for which there is no effective treatment. Despite scientific evidence that Staphylococcus bacteria are the most common causative species for human bacterial chondronecrosis with osteomyelitis (BCO), much remains to be understood about the underlying virulence mechanisms. Herein, we show increased levels of double-stranded RNA (dsRNA) in infected bone in a Staphylococcus-induced chicken BCO model and in human osteomyelitis samples. Administration of synthetic [poly(I:C)] or genetic (Alu) dsRNA induces human osteoblast cell death. Similarly, infection with Staphylococcus isolated from chicken BCO induces dsRNA accumulation and cell death in human osteoblast cell cultures. Both dsRNA administration and Staphylococcus infection activate NACHT, LRR and PYD domains-containing protein (NLRP)3 inflammasome and increase IL18 and IL1B gene expression in human osteoblasts. Pharmacologic inhibition with Ac-YVAD-cmk of caspase 1, a critical component of the NLRP3 inflammasome, prevents DICER1 dysregulation- and dsRNA-induced osteoblast cell death. NLRP3 inflammasome and its components are also activated in bone from BCO chickens and humans with osteomyelitis, compared with their healthy counterparts. These findings provide a rationale for the use of chicken BCO as a human-relevant spontaneous animal model for osteomyelitis and identify dsRNA as a new treatment target for this debilitating bone pathogenesis.
骨髓炎仍然是一种严重的炎症性骨病,影响着全球数以百万计的人群,而目前尚无有效的治疗方法。尽管有科学证据表明葡萄球菌是导致人类细菌性软骨坏死伴骨髓炎(BCO)的最常见病原体,但对于其潜在的毒力机制仍有许多需要了解。在此,我们在葡萄球菌诱导的鸡 BCO 模型和人类骨髓炎样本中发现感染骨中的双链 RNA(dsRNA)水平升高。合成的[poly(I:C)]或遗传(Alu)dsRNA的给药会诱导人成骨细胞死亡。同样,从鸡 BCO 中分离出的金黄色葡萄球菌感染会导致 dsRNA 积累和人成骨细胞培养物中的细胞死亡。dsRNA 给药和金黄色葡萄球菌感染均可激活 NACHT、LRR 和 PYD 结构域包含蛋白(NLRP)3 炎症小体,并增加人成骨细胞中 IL18 和 IL1B 基因的表达。用 caspase 1 的关键成分 Ac-YVAD-cmk 进行药理学抑制可防止 DICER1 失调和 dsRNA 诱导的成骨细胞死亡。与健康对照组相比,BCO 鸡和患有骨髓炎的人类的骨中也会激活 NLRP3 炎症小体及其成分。这些发现为使用鸡 BCO 作为人类相关自发性骨髓炎动物模型提供了依据,并确定 dsRNA 是这种使人衰弱的骨发病机制的新治疗靶点。
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