NADPH Oxidase and Guanylate Binding Protein 5 Restrict Survival of Avirulent Type III Strains of Toxoplasma gondii in Naive Macrophages

Matta, Sumit Kumar; Patten, Kelley T; Wang, Quiling; Kim, Bae-Hoon; MacMicking, John D.; Sibley, L. David

doi:10.1128/mbio.01393-18

Cited by 42 publications

(45 citation statements)

References 76 publications

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“…Mice surviving to chronic infection were killed, and half of their brains was harvested in 1 mL of 6% (vol/vol) formaldehyde and 0.25% (vol/vol) Triton X-100 in cold PBS. Cyst burden in each sample was estimated as described previously (68). Cysts were stained with 20 μg/mL FITC-conjugated DBL in 10% goat serum.…”

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confidence: 99%

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Toxoplasma gondiieffector TgIST blocks type I interferon signaling to promote infection

Matta

Olias

Huang

et al. 2019

Proc. Natl. Acad. Sci. U.S.A.

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In contrast to the importance of type II interferon-γ (IFN-γ) in control of toxoplasmosis, the role of type I IFN is less clear. We demonstrate here that TgIST, a secreted effector previously implicated in blocking type II IFN-γ signaling, also blocked IFN-β responses by inhibiting STAT1/STAT2-mediated transcription in infected cells. Consistent with a role for type I IFN in cell intrinsic control, ∆Tgist mutants were more susceptible to growth inhibition by murine and human macrophages activated with IFN-β. Additionally, type I IFN was important for production of IFN-γ by natural killer (NK) cells and recruitment of inflammatory monocytes at the site of infection. Mice lacking type I IFN receptors (Ifnar1−/−) showed increased mortality following infection with wild-type parasites and decreased virulence of ∆Tgist parasites was restored in Ifnar1−/− mice. The findings highlight the importance of type I IFN in control of toxoplasmosis and illuminate a parasite mechanism to counteract the effects of both type I and II IFN-mediated host defenses.

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confidence: 99%

“…or 5 ME49 cysts orally. Mice were killed 3 and 6 d postinfection with PRU KO, followed by isolation of the peritoneal cells as described previously (68). In ME49 cyst infection, the mice were first perfused with PBS and half of the brain was removed and kept in RPMI.…”

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confidence: 99%

Toxoplasma gondiieffector TgIST blocks type I interferon signaling to promote infection

Matta

Olias

Huang

et al. 2019

Proc. Natl. Acad. Sci. U.S.A.

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“…Like the IRGs, GBPs also accumulate on the PVM shortly after invasion by T. gondii, an action which is inhibited by virulent strains of the parasite. Unlike the IRGs, which cause direct disruption of the PVM, GBPs act by recruiting protein complexes to the membrane, such as the inflammosome, autophagy apparatus, and NOX2 NADPH oxidase, which have antimicrobial functions [35,36,37,38,39]. In the current study, the majority of known GBPs from both the chromosome 3 and 5 clusters were found to be upregulated during infection with all three strain types.…”

Section: Discussionmentioning

confidence: 48%

Dynamics of Gene Expression in Mice Infected with Different Genotypes of Toxoplasma gondii

Yu¹,

Shwab²,

Hill³

et al. 2019

Preprint

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Background: Toxoplasma gondii is genetically diverse and different genotypes differ markedly in phenotype. The present study aims to define transcriptional patterns and biological processes that characterize host response to distinct strains of T. gondii. Methods: We conducted a time course study of gene expression microarray in mice during acute infection (days 1 to 7) with the highly virulent type I (GT1 strain), intermediately virulent type II (PTG strain) and non-virulent type III (CTG strain) parasites. Results: Overall, the number of genes affected increased from day 1 to day 5, and decreased on day 7. However, type III and type II infections up-regulated more genes than did type I at the very early phase, whereas type I infection up-regulated more genes at the late phase. Gene ontology (GO) analysis showed that the genes related to inflammatory and immune response were mostly affected and the majority were up-regulated, with type III infection inducing a higher degree of change and affecting more genes than did type I at the early phase. However, this pattern was reversed at the late phase. The change of expression during type II infection was between that of types I and III. Many genes associated with inflammatory and immune responses showed bimodal effects, with the first peak expression mostly at day 3 and then a second peak expression mostly at day 5. Several differentially expressed genes, including INF-γ, iNOS, CXCL10/IP-10, and numerous immunity-related GTPases (IRGs) and guanylate-binding proteins (GBPs) were previously experimentally confirmed important host factors in controlling T. gondii infection. Bioinformatic analysis of biological pathways enriched during infection revealed upregulation of pathways relating to cell-mediated immunity and the inflammatory response during all three infection types, though such enrichment was most expansive and pronounced during type I infection, and much less pronounced during type III infection. Conclusions: The findings in our study revealed dynamic differences of gene expression and different pathways of immune response in mice infected with three distinct strains of T. gondii.

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“…IFA was carried out as previously described [12]. Briefly, cells grown on coverslips in a 24-well plate were fixed with 4% paraformaldehyde in phosphate-buffered saline (PBS) for 10 min and permeabilized with 0.25% triton-PBS for 10 min.…”

Section: Ifamentioning

confidence: 99%

“…Interestingly, infections by both avirulent Type III (CTG strain) and virulent Type I (GT1 strain) trigger ROS production in the infected macrophages. CTG-strain parasites are mainly cleared by the naive macrophages in a manner depending on NADPH oxidase-generated ROS without activation of interferon gamma [12]. Due to ROS' potential detrimental impact on DNA, we explored the association between elevated ROS levels and host DNA damage during T. gondii infection.…”

Section: Introductionmentioning

confidence: 99%

DNA double-strand breaks in the Toxoplasma gondii-infected cells by the action of reactive oxygen species

et al. 2020

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Background Toxoplasma gondii is an obligate parasite of all warm-blooded animals around the globe. Once infecting a cell, it manipulates the host’s DNA damage response that is yet to be elucidated. The objectives of the present study were three-fold: (i) to assess DNA damages in T. gondii-infected cells in vitro; (ii) to ascertain causes of DNA damage in T. gondii-infected cells; and (iii) to investigate activation of DNA damage responses during T. gondii infection. Methods HeLa, Vero and HEK293 cells were infected with T. gondii at a multiplicity of infection (MOI) of 10:1. Infected cells were analyzed for a biomarker of DNA double-strand breaks (DSBs) γH2AX at 10 h, 20 h or 30 h post-infection using both western blot and immunofluorescence assay. Reactive oxygen species (ROS) levels were measured using 2′,7′-dichlorodihydrofluorescein diacetate (H2DCFDA), and ROS-induced DNA damage was inhibited by a ROS inhibitor N-acetylcysteine (NAC). Lastly, DNA damage responses were evaluated by detecting the active form of ataxia telangiectasia mutated/checkpoint kinase 2 (ATM/CHK2) by western blot. Results γH2AX levels in the infected HeLa cells were significantly increased over time during T. gondii infection compared to uninfected cells. NAC treatment greatly reduced ROS and concomitantly diminished γH2AX in host cells. The phosphorylated ATM/CHK2 were elevated in T. gondii-infected cells. Conclusions Toxoplasma gondii infection triggered DNA DSBs with ROS as a major player in host cells in vitro. It also activated DNA damage response pathway ATM/CHK2. Toxoplasma gondii manages to keep a balance between survival and apoptosis of its host cells for the benefit of its own survival.

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NADPH Oxidase and Guanylate Binding Protein 5 Restrict Survival of Avirulent Type III Strains of Toxoplasma gondii in Naive Macrophages

Cited by 42 publications

References 76 publications

Toxoplasma gondiieffector TgIST blocks type I interferon signaling to promote infection

Toxoplasma gondiieffector TgIST blocks type I interferon signaling to promote infection

Dynamics of Gene Expression in Mice Infected with Different Genotypes of Toxoplasma gondii

DNA double-strand breaks in the Toxoplasma gondii-infected cells by the action of reactive oxygen species

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