Tartaglia Natayme R, Breyne Koen, Meyer Evelyne, Cauty Chantal, Jardin Julien, Chrétien Denis, Dupont Aurélien, Demeyere Kristel, Berkova Nadia, Azevedo Vasco, Guédon Eric, Le Loir Yves
STLO, INRA, Agrocampus Ouest, Rennes, France.
Federal University of Minas Gerais, Belo Horizonte, Brazil.
Front Cell Infect Microbiol. 2018 Aug 22;8:277. doi: 10.3389/fcimb.2018.00277. eCollection 2018.
is a major pathogen responsible for bovine mastitis, the most common and costly disease affecting dairy cattle. naturally releases extracellular vesicles (EVs) during its growth. EVs play an important role in the bacteria-bacteria and bacteria-host interactions and are notably considered as nanocarriers that deliver virulence factors to the host tissues. Whether EVs play a role in a mastitis context is still unknown. In this work, we showed that Newbould 305 (N305), a bovine mastitis isolate, has the ability to generate EVs with a designated protein content. Purified N305-secreted EVs were not cytotoxic when tested on MAC-T and PS, two bovine mammary epithelial cell lines. However, they induced the gene expression of inflammatory cytokines at levels similar to those induced by live N305. The immune response to purified N305-secreted EVs was tested in a mouse model for bovine mastitis and their immunogenic effect was compared to that of live N305, heat-killed N305 and to lipoteichoic acid (LTA). Clinical and histopathological signs were evaluated and pro-inflammatory and chemotactic cytokine levels were measured in the mammary gland 24 h post-inoculation. Live induced a significantly stronger inflammatory response than that of any other condition tested. Nevertheless, N305-secreted EVs induced a dose-dependent neutrophil recruitment and the production of a selected set of pro-inflammatory mediators as well as chemokines. This immune response elicited by intramammary N305-secreted EVs was comparable to that of heat-killed N305 and, partly, by LTA. These results demonstrated that N305-secreted EVs induce a mild inflammatory response distinct from the live pathogen after intramammary injection. Overall, our combined and data suggest that EVs are worth to be investigated to better understand the pathogenesis and are relevant tools to develop strategies against bovine mastitis.
是引起牛乳腺炎的主要病原体，牛乳腺炎是影响奶牛的最常见且代价高昂的疾病。在其生长过程中自然释放细胞外囊泡（EVs）。EVs在细菌 - 细菌和细菌 - 宿主相互作用中起重要作用，并且特别被认为是将毒力因子传递到宿主组织的纳米载体。EVs在乳腺炎背景下是否发挥作用仍然未知。在这项工作中，我们表明，一种牛乳腺炎分离株纽博尔德305（N305）具有产生具有特定蛋白质含量的EVs的能力。在两种牛乳腺上皮细胞系MAC - T和PS上进行测试时，纯化的N305分泌的EVs没有细胞毒性。然而，它们诱导炎症细胞因子的基因表达水平与活的N305诱导的水平相似。在牛乳腺炎小鼠模型中测试了对纯化的N305分泌的EVs的免疫反应，并将它们的免疫原性效应与活的N305、热灭活的N305以及脂磷壁酸（LTA）的免疫原性效应进行了比较。在接种后24小时评估乳腺的临床和组织病理学体征，并测量促炎和趋化细胞因子水平。活的N305诱导的炎症反应明显强于测试的任何其他条件。然而，N305分泌的EVs诱导剂量依赖性的中性粒细胞募集以及一组选定的促炎介质和趋化因子的产生。乳腺内注射N305分泌的EVs引发的这种免疫反应与热灭活的N305相当，并且部分与LTA相当。这些结果表明，N305分泌的EVs在乳腺内注射后诱导与活病原体不同的轻度炎症反应。总体而言，我们的综合数据表明，EVs值得研究以更好地理解发病机制，并且是开发抗牛乳腺炎策略的相关工具。
