Animal Health Laboratory, Department of Veterinary Science, School of Veterinary Medicine, Rakuno Gakuen University, Ebetsu, Hokkaido, Japan.
Laboratory of Veterinary Biochemistry, Department of Veterinary Science, School of Veterinary Medicine, Rakuno Gakuen University, Ebetsu, Hokkaido, Japan.
Vet Microbiol. 2021 Feb;253:108956. doi: 10.1016/j.vetmic.2020.108956. Epub 2020 Dec 13.
Mycoplasma bovis causes chronic arthritis in cattle, accompanied by a severe inflammatory reaction of the joints. Recent studies demonstrated that M. bovis can invade bovine non-phagocytic cells, but the mechanism of M. bovis internalization in the cells remains unclear. In this study, we examined the mechanism by which M. bovis invades synovial cells, including the pathway of cell invasion. Using fluorescence and electron microscopy, multiple M. bovis were observed to adhere to and be internalized in cultured bovine synovial cells. The number of M. bovis colocalized with clathrin heavy chain (CLTC) per cell was significantly higher than the number of M. bovis colocalized with caveolin-1 (Cav-1). The internalized ratio of M. bovis in synovial cells treated with clathrin-dependent endocytosis inhibitor and small interfering RNA (siRNA) against CLTC was significantly lower than that in control cells. In contrast, the internalized ratio of M. bovis in synovial cells was unaffected by siRNA against Cav-1. These findings provide the first evidence that clathrin-dependent endocytosis is one of the major pathways by which M. bovis invades into synovial cells.
牛支原体引起牛慢性关节炎，伴有关节严重炎症反应。最近的研究表明，牛支原体可以侵入牛非吞噬细胞，但牛支原体在细胞内内化的机制尚不清楚。在这项研究中，我们研究了牛支原体侵袭滑膜细胞的机制，包括细胞入侵的途径。使用荧光和电子显微镜，观察到多个牛支原体附着并内化在培养的牛滑膜细胞中。每个细胞中与网格蛋白重链（CLTC）共定位的牛支原体数量明显高于与窖蛋白-1（Cav-1）共定位的牛支原体数量。用网格蛋白依赖性内吞作用抑制剂和针对 CLTC 的小干扰 RNA（siRNA）处理的滑膜细胞中牛支原体的内化率明显低于对照细胞。相比之下，针对 Cav-1 的 siRNA 对滑膜细胞中牛支原体的内化率没有影响。这些发现首次提供证据表明，网格蛋白依赖性内吞作用是牛支原体侵入滑膜细胞的主要途径之一。
