Bta-miR-199a-3p in embryonic bovine lung cells-derived extracellular vesicles enhances pro-inflammatory cytokine expression in macrophages via DUSP5 upregulation during Mycoplasma bovis infection.

Mycoplasma bovis (M. bovis), mainly causes pneumonia, mastitis, and arthritis in cattle, thereby leading to significant economic losses. The pathological damage caused by inflammation is key to the pathogenesis of M. bovis. The aim of this study was to reveal the role of extracellular vesicles (EVs) in M. bovis-host interaction and identified the key miRNAs in EVs. We used ultracentrifugation method to extract the EVs from the embryonic bovine lung (EBL) cells infected with M. bovis, then identified the miRNA profile of EVs by RNA sequencing. We identified 12 upregulated and 6 downregulated miRNAs in EVs + (derived from infected EBL cells) as compared to EVs- (uninfected controls). Furthermore, EVs + possessed the greater capacity to induce production of IL-1β, IL-6, IL-8, and TNF-α by bovine macrophage BoMac cells than EVs-, and enhanced the sensitivity of BoMac cells to produce pro-inflammatory cytokines upon infection of M. bovis. Additionally, bta-miR-199a-3p in EVs + promoted production of IL-6, IL-8, and TNF-α by BoMac cells via increasing expression of the target gene dual specificity phosphatase 5 (DUSP5). Collectively, these results suggested that EVs derived from epithelia cells EBL enhance the sensitivity of macrophage BoMac to response M. bovis infection. Moreover, bta-miR-199a-3p enriched in EVs + regulated the immune response of BoMac via up-regulation of DUSP5. These findings highlighted the roles of EVs in host cell resistance to M. bovis infection and provided new insights to explore the pathogenic mechanism of M. bovis.