Centre for Integrative Physiology, The University of Edinburgh, Edinburgh, UK; Musculoskeletal Research Unit, Department of Orthopaedic and Trauma Surgery, The University of Edinburgh, Edinburgh, UK.
Osteoarthritis Cartilage. 2013 Nov;21(11):1755-65. doi: 10.1016/j.joca.2013.07.013. Epub 2013 Jul 27.
To assess in situ chondrocyte viability following exposure to a laboratory strain and clinical isolates of Staphylococcus aureus.
Bovine cartilage explants were cultured in the presence of S. aureus 8325-4 (laboratory strain), clinical S. aureus isolates or non-infected culture medium of pH values 7.4, 6.4 and 5.4. All clinical isolates were isolated from the joint aspirates of patients presenting with S. aureus-induced septic arthritis (SA). At designated time points, in situ chondrocyte viability was assessed within defined regions-of-interest in the axial and coronal plane following live- and dead-cell image acquisition using the fluorescent probes 5-chloromethylfluorescein diacetate (CMFDA) and propidium iodide (PI), respectively, and confocal laser-scanning microscopy (CLSM). Cartilage water content, following S. aureus 8325-4 exposure, was obtained by measuring cartilage wet and dry weights.
S. aureus 8325-4 and clinical S. aureus isolates rapidly reduced in situ chondrocyte viability (>45% chondrocyte death at 40 h). The increased acidity, observed during bacterial culture, had a minimal effect on chondrocyte viability. Chondrocyte death commenced within the superficial zone (SZ) and rapidly progressed to the deep zone (DZ). Simultaneous exposure of SZ and DZ chondrocytes to S. aureus 8325-4 toxins found SZ chondrocytes to be more susceptible to the toxins than DZ chondrocytes. Cartilage water content was not significantly altered compared to non-infected controls.
Toxins released by S. aureus have a rapid and fatal action on in situ chondrocytes in this experimental model of SA. These data advocate the prompt and thorough removal of bacteria and their toxins during the treatment of SA.
评估金黄色葡萄球菌实验室株和临床分离株暴露后原位软骨细胞活力。
牛软骨标本在金黄色葡萄球菌 8325-4（实验室株）、临床金黄色葡萄球菌分离株或 pH 值为 7.4、6.4 和 5.4 的非感染培养基存在的情况下进行培养。所有临床分离株均从金黄色葡萄球菌引起的化脓性关节炎（SA）患者的关节抽吸液中分离出来。在指定的时间点，使用荧光探针 5-氯甲基荧光素二乙酸酯（CMFDA）和碘化丙啶（PI）分别获取活细胞和死细胞图像后，在轴向和冠状平面上的特定感兴趣区域评估原位软骨细胞活力，并使用共聚焦激光扫描显微镜（CLSM）进行检测。金黄色葡萄球菌 8325-4 暴露后，通过测量软骨的湿重和干重来获得软骨含水量。
金黄色葡萄球菌 8325-4 和临床金黄色葡萄球菌分离株迅速降低原位软骨细胞活力（40 小时时>45%的软骨细胞死亡）。在细菌培养过程中观察到的酸度增加对软骨细胞活力的影响很小。软骨细胞死亡首先发生在浅层区（SZ），并迅速向深层区（DZ）发展。同时将 SZ 和 DZ 软骨细胞暴露于金黄色葡萄球菌 8325-4 毒素中，发现 SZ 软骨细胞比 DZ 软骨细胞更容易受到毒素的影响。与非感染对照组相比，软骨含水量没有明显改变。
金黄色葡萄球菌释放的毒素在这种化脓性关节炎的实验模型中对原位软骨细胞具有快速和致命的作用。这些数据表明，在治疗化脓性关节炎时，应迅速彻底清除细菌及其毒素。
