Department of Medical Microbiology, Institute of Microbiology, Rio de Janeiro Federal University (IMPPG/UFRJ), Rio de Janeiro, RJ, Brazil.
Laboratory of Diphtheria and Corynebacteria of Clinical Relevance (LDCIC), Faculty of Medical Sciences, Rio de Janeiro State University (UERJ), Rio de Janeiro, RJ, Brazil.
Microbiology (Reading). 2014 Mar;160(Pt 3):537-546. doi: 10.1099/mic.0.069948-0. Epub 2013 Dec 16.
Although infection by Corynebacterium diphtheriae is a model of extracellular mucosal pathogenesis, different clones have been also associated with invasive infections such as sepsis, endocarditis, septic arthritis and osteomyelitis. The mechanisms that promote C. diphtheriae infection and haematogenic dissemination need further investigation. In this study we evaluated the association and invasion mechanisms with human umbilical vein endothelial cells (HUVECs) and experimental arthritis in mice of endocarditis-associated strains and control non-invasive strains. C. diphtheriae strains were able to adhere to and invade HUVECs at different levels. The endocarditis-associated strains displayed an aggregative adherence pattern and a higher number of internalized viable cells in HUVECs. Transmission electron microscopy (TEM) analysis revealed intracellular bacteria free in the cytoplasm and/or contained in a host-membrane-confined compartment as single micro-organisms. Data showed bacterial internalization dependent on microfilament and microtubule stability and involvement of protein phosphorylation in the HUVEC signalling pathway. A high number of affected joints and high arthritis index in addition to the histopathological features indicated a strain-dependent ability of C. diphtheriae to cause severe polyarthritis. A correlation between the arthritis index and increased systemic levels of IL-6 and TNF-α was observed for endocarditis-associated strains. In conclusion, higher incidence of potential mechanisms by which C. diphtheriae may access the bloodstream through the endothelial barrier and stimulate the production of pro-inflammatory cytokines such as IL-6 and TNF-α, in addition to the ability to affect the joints and induce arthritis through haematogenic spread are thought to be related to the pathogenesis of endocarditis-associated strains.
虽然白喉棒状杆菌感染是一种细胞外黏膜发病机制的模型，但不同的克隆也与侵袭性感染有关，如败血症、心内膜炎、化脓性关节炎和骨髓炎。促进白喉棒状杆菌感染和血源传播的机制需要进一步研究。在这项研究中，我们评估了与人类脐静脉内皮细胞（HUVEC）的关联和侵袭机制，以及实验性关节炎在小鼠的心内膜炎相关菌株和对照非侵袭性菌株中的作用。白喉棒状杆菌菌株能够在不同水平上黏附和侵袭 HUVEC。心内膜炎相关菌株表现出聚集性黏附模式和更多的内化活细胞在 HUVEC 中。透射电子显微镜（TEM）分析显示，细胞内细菌在细胞质中自由存在，或包含在宿主膜封闭的隔室中，作为单个微生物。数据显示，细菌的内化依赖于微丝和微管的稳定性，以及宿主细胞信号通路中的蛋白磷酸化。大量受影响的关节和高关节炎指数，以及组织病理学特征表明，白喉棒状杆菌具有引起严重多关节炎的菌株依赖性能力。观察到心内膜炎相关菌株的关节炎指数与系统性升高的白细胞介素-6（IL-6）和肿瘤坏死因子-α（TNF-α）水平之间存在相关性。总之，白喉棒状杆菌可能通过内皮屏障进入血液并刺激白细胞介素-6（IL-6）和肿瘤坏死因子-α（TNF-α）等促炎细胞因子产生的潜在机制的发生率更高，此外，通过血源传播影响关节和诱导关节炎的能力被认为与心内膜炎相关菌株的发病机制有关。
