In VitroInfection of Bovine Monocytes with Mycoplasma bovis Delays Apoptosis and Suppresses Production of Gamma Interferon and Tumor Necrosis Factor Alpha but Not Interleukin-10

Abstract

ABSTRACTMycoplasma bovisis one of the major causative pathogens of bovine respiratory complex disease (BRD), which is characterized by enzootic pneumonia, mastitis, pleuritis, and polyarthritis.M. bovisenters and colonizes bovine respiratory epithelial cells through inhalation of aerosol from contaminated air. The nature of the interaction betweenM. bovisand the bovine innate immune system is not well understood. We hypothesized thatM. bovisinvades blood monocytes and regulates cellular function to support its persistence and systemic dissemination. We used bovine-specific peptide kinome arrays to identify cellular signaling pathways that could be relevant toM. bovis-monocyte interactionsin vitro. We validated these pathways using functional, protein, and gene expression assays. Here, we show that infection of bovine blood monocytes withM. bovisdelays spontaneous or tumor necrosis factor alpha (TNF-α)/staurosporine-driven apoptosis, activates the NF-κB p65 subunit, and inhibits caspase-9 activity. We also report thatM. bovis-infected bovine monocytes do not produce gamma interferon (IFN-γ) and TNF-α, although the level of production of interleukin-10 (IL-10) is elevated. Our findings suggest thatM. bovistakes over the cellular machinery of bovine monocytes to prolong bacterial survival and to possibly facilitate subsequent systemic distribution.