Abstract
Nicotinamide adenine dinucleotide phosphate (NADPH) oxidases (Nox) are an important family of catalytic enzymes that generate reactive oxygen species (ROS), which mediate the regulation of diverse cellular functions. Although phagocyte Nox2/gp91phox is closely associated with the activation of host innate immune responses, the roles of Nox family protein during Toxoplasma gondii (T. gondii) infection have not been fully investigated. Here, we found that T. gondii-mediated ROS production was required for the upregulation of macrophage migration inhibitory factor (MIF) mRNA and protein levels via activation of mitogen-activated protein kinase and nuclear factor-κB signaling in macrophages. Interestingly, MIF knockdown led to a significant increase in the survival of intracellular T. gondii in bone marrow-derived macrophages (BMDMs). Moreover, Nox4 deficiency, but not Nox2/gp91phox and the cytosolic subunit p47phox, resulted in enhanced survival of the intracellular T. gondii RH strain and impaired expression of T. gondii-mediated MIF in BMDMs. Additionally, Nox4-deficient mice showed increased susceptibility to virulent RH strain infection and increased cyst burden in brain tissues and low levels of MIF expression following infection with the avirulent ME49 strain. Collectively, our findings indicate that Nox4-mediated ROS generation plays a central role in MIF production and resistance to T. gondii infection.
Highlights
Toxoplasma gondii (T. gondii) is an obligate protozoan parasite that infects a broad range of warm-blooded animals, including avian and mammalian species[1]
The results showed that T. gondii-mediated protein (Fig. 1A) and mRNA (Fig. S1A) migration inhibitory factor (MIF) levels were induced initially, from 6 h after infection, and increased continually until 48 h in bone marrow-derived macrophages (BMDMs)
BMDMs were transduced with various lentiviral short hairpin RNAs against Mif, and the efficiency of lentiviral transduction was assessed by semi-quantitative reverse transcription (RT)-polymerase chain reaction (PCR) (Fig. S2, top)
Summary
Toxoplasma gondii (T. gondii) is an obligate protozoan parasite that infects a broad range of warm-blooded animals, including avian and mammalian species[1]. More recent studies have demonstrated that MIF is expressed constitutively in various cells, such as monocytes, macrophages, and endothelial cells, and has multiple activities in inflammatory responses and host anti-microbial immunity[16,17,18]. MIF is involved in the pathogenesis and host immune responses to infection with various intracellular parasitic protozoa, including Plasmodium[19], Leishmania[20, 21], Trypanosoma[22], and Toxoplasma[23, 24]. We examined the precise role of Nox family proteins in innate immune control against Toxoplasma infection using primary macrophages and an in vivo murine model. T. gondii stimulation resulted in rapid activation of NF-κB and mitogen-activating protein kinases (MAPKs), and the generation of intracellular ROS in macrophages, which is important for T. gondii-mediated MIF expression. Our findings indicate that Nox4-derived ROS are an important mediator of MIF generation for anti-parasitic defence
Sign-in/Register to view highlights & summary Talk to us
Join us for a 30 min session where you can share your feedback and ask us any queries you have
Schedule a callDisclaimer: All third-party content on this website/platform is and will remain the property of their respective owners and is provided on "as is" basis without any warranties, express or implied. Use of third-party content does not indicate any affiliation, sponsorship with or endorsement by them. Any references to third-party content is to identify the corresponding services and shall be considered fair use under The CopyrightLaw.
