Modulation of Macrophage Redox and Apoptotic Processes to during Coinfection with the Tick-Borne Bacteria .

Canine leishmaniosis (CanL) is a zoonotic disease caused by protozoan . Dogs with CanL are often coinfected with tick-borne bacterial pathogens, including in the United States. These coinfections have been causally associated with hastened disease progression and mortality. However, the specific cellular mechanisms of how coinfections affect microbicidal responses against are unknown. We hypothesized that coinfection impacts host macrophage effector functions, prompting intracellular survival. In vitro experiments demonstrated that exposure to spirochetes significantly increased parasite burden and pro-inflammatory responses in DH82 canine macrophage cells. Induction of cell death and generation of mitochondrial ROS were significantly decreased in coinfected DH82 cells compared to uninfected and -infected cells. Ex vivo stimulation of PBMCs from -seronegative and -seropositive subclinical dogs with spirochetes and/or total antigens promoted limited induction of IFNγ. Coexposure significantly induced expression of pro-inflammatory cytokines and chemokines associated with Th17 differentiation and neutrophilic and monocytic recruitment in PBMCs from -seropositive dogs. Excessive pro-inflammatory responses have previously been shown to cause CanL pathology. This work supports effective tick prevention and risk management of coinfections as critical strategies to prevent and control progression in dogs.