Life Science School, Ningxia University, Yinchuan 750021, China.
Key Laboratory of Ministry of Education for Conservation and Utilization of Special Biological Resources in the Western, Ningxia University, Yinchuan 750021, China.
Int J Mol Sci. 2022 Aug 28;23(17):9742. doi: 10.3390/ijms23179742.
Rhodococcus equi (R. equi) is a Gram-positive coccobacillus that causes pneumonia in foals of less than 3 months, which have the ability of replication in macrophages. The ability of R. equi persist in macrophages is dependent on the virulence plasmid pVAPA. Gram-positive extracellular vesicles (EVs) carry a variety of virulence factors and play an important role in pathogenic infection. There are few studies on R. equi-derived EVs (R. equi-EVs), and little knowledge regarding the mechanisms of how R. equi-EVs communicate with the host cell. In this study, we examine the properties of EVs produced by the virulence strain R. equi 103+ (103+-EVs) and avirulenct strain R. equi 103− (103−-EVs). We observed that 103+-EVs and 103−-EVs are similar to other Gram-positive extracellular vesicles, which range from 40 to 260 nm in diameter. The 103+-EVs or 103−-EVs could be taken up by mouse macrophage J774A.1 and cause macrophage cytotoxicity. Incubation of 103+-EVs or 103−-EVs with J774A.1 cells would result in increased expression levels of IL-1β, IL-6, and TNF-α. Moreover, the expression of TLR2, p-NF-κB, p-p38, and p-ERK were significantly increased in J774A.1 cells stimulated with R. equi-EVs. In addition, we presented that the level of inflammatory factors and expression of TLR2, p-NF-κB, p-p38, and p-ERK in J774A.1 cells showed a significant decreased when incubation with proteinase K pretreated-R. equi-EVs. Overall, our data indicate that R. equi-derived EVs are capable of mediating inflammatory responses in macrophages via TLR2-NF-κB/MAPK pathways, and R. equi-EVs proteins were responsible for TLR2-NF-κB/MAPK mediated inflammatory responses in macrophage. Our study is the first to reveal potential roles for R. equi-EVs in immune response in R. equi-host interactions and to compare the differences in macrophage inflammatory responses mediated by EVs derived from virulent strain R. equi and avirulent strain R. equi. The results of this study have improved our knowledge of the pathogenicity of R. equi.
马红球菌（R. equi）是一种革兰阳性球杆菌，可引起 3 个月以下小马驹的肺炎，其具有在巨噬细胞中复制的能力。R. equi 在巨噬细胞中的持续存在能力依赖于毒力质粒 pVAPA。革兰阳性细胞外囊泡（EVs）携带多种毒力因子，在致病感染中发挥重要作用。目前关于马红球菌来源的 EVs（R. equi-EVs）的研究较少，关于 R. equi-EVs 如何与宿主细胞通讯的知识也很少。在这项研究中，我们研究了毒力株 R. equi 103+（103+-EVs）和无毒株 R. equi 103−（103−-EVs）产生的 EVs 的特性。我们观察到 103+-EVs 和 103−-EVs 与其他革兰阳性细胞外囊泡相似，直径为 40 至 260nm。103+-EVs 或 103−-EVs 可被小鼠巨噬细胞 J774A.1 摄取并导致巨噬细胞细胞毒性。103+-EVs 或 103−-EVs 与 J774A.1 细胞孵育会导致 IL-1β、IL-6 和 TNF-α 的表达水平增加。此外，用 R. equi-EVs 刺激 J774A.1 细胞会导致 TLR2、p-NF-κB、p-p38 和 p-ERK 的表达显著增加。此外，当用预先用蛋白酶 K 处理的 R. equi-EVs 孵育时，J774A.1 细胞中的炎症因子水平和 TLR2、p-NF-κB、p-p38 和 p-ERK 的表达均显著降低。总体而言，我们的数据表明，R. equi 衍生的 EVs 能够通过 TLR2-NF-κB/MAPK 途径介导巨噬细胞中的炎症反应，并且 R. equi-EVs 蛋白负责 TLR2-NF-κB/MAPK 介导的巨噬细胞中的炎症反应。我们的研究首次揭示了 R. equi-EVs 在 R. equi-宿主相互作用中的免疫反应中的潜在作用，并比较了来自毒力株 R. equi 和无毒株 R. equi 的 EVs 介导的巨噬细胞炎症反应的差异。本研究的结果提高了我们对 R. equi 致病性的认识。
