Division of Orthopaedics and Traumatology, Department of Orthopaedics, Nanfang Hospital, Southern Medical University, Guangzhou, China.
Guangdong Provincial Key Laboratory of Bone and Cartilage Regenerative Medicine, Nanfang Hospital, Southern Medical University, Guangzhou, China.
Cell Microbiol. 2020 Oct;22(10):e13240. doi: 10.1111/cmi.13240. Epub 2020 Aug 6.
Internalisation of Staphylococcus aureus in osteoblasts plays a critical role in the persistence and recurrence of osteomyelitis, the mechanisms involved in this process remain largely unknown. In the present study, evidence of internalised S. aureus in osteoblasts was found in long bone of haematogenous osteomyelitis in mice after 2 weeks of infection. Meanwhile, eliminating extracellular S. aureus by gentamicin can partially rescue bone loss, whereas the remaining intracellular S. aureus in osteoblasts may be associated with continuous bone destruction. In osteoblastic MC3T3 cells, intracellular S. aureus was detectable as early as 15 min after infection, and the internalisation rates increased with the extension of infection time. Additionally, S. aureus invasion stimulated the expression of phosphor-focal adhesion kinase (FAK), phosphor-epidermal growth factor receptor (EGFR) and phosphor-c-Src in a time-dependent way, and blocking EGFR/FAK or c-Src signalling significantly reduced the internalisation rate of S. aureus in osteoblasts. Our findings provide new insights into the mechanism of S. aureus internalisation in osteoblast and raise the potential of targeting EGFR/FAK and c-Src as adjunctive therapeutics for treating chronic S. aureus osteomyelitis.
金黄色葡萄球菌在成骨细胞内的内化在骨髓炎的持续和复发中起着关键作用,但其具体机制仍知之甚少。本研究发现,在感染 2 周后的血源性骨髓炎小鼠长骨中,可发现成骨细胞内内化的金黄色葡萄球菌。同时,庆大霉素清除细胞外金黄色葡萄球菌可部分挽救骨丢失,而在成骨细胞中残留的细胞内金黄色葡萄球菌可能与持续的骨破坏有关。在成骨细胞 MC3T3 细胞中,感染后 15 分钟即可检测到细胞内金黄色葡萄球菌,且内化率随感染时间的延长而增加。此外,金黄色葡萄球菌的入侵以时间依赖性方式刺激磷-黏着斑激酶(FAK)、磷-表皮生长因子受体(EGFR)和磷-c-Src 的表达,阻断 EGFR/FAK 或 c-Src 信号通路可显著降低金黄色葡萄球菌在成骨细胞内的内化率。我们的研究结果为金黄色葡萄球菌内化进入成骨细胞的机制提供了新的见解,并提示靶向 EGFR/FAK 和 c-Src 作为辅助治疗慢性金黄色葡萄球菌骨髓炎的潜在可能性。
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