Project description:Toxoplasma strains are known to inhibit the expression of several interferon-gamma induced genes, and a type II strain was shown to dysregulate genome-wide responses to interferon-gamma in human fibroblasts (Kim et al., 2007, J Immunol.). In this study we aimed to determine the effect of infection with three clonal lineages of Toxoplasma, type I, II, and III strains on genome-wide interferon-gamma induced transcription in murine macrophages. We also assessed the effect of the two main Toxoplasma modulators of mouse macrophage transcription, ROP16 and GRA15 (Jensen et al., 2011, Cell Host Microbe). We used Affymetrix microarrays to analyze host cell transcription after Toxoplasma infection and interferon-gamma stimulation. RAW264.7 murine macrophages were left uninfected or infected with type I (RH), type I ?rop16 (RH ?rop16), type II (Pru), type II ?gra15 (Pru ?gra15), or type II (CEP) parasites at an MOI ~5 for 18 hours and subsequently stimulated with murine IFN-? for six hours. Plaque assays were done to assess parasite viability. Total RNA was isolated and hybridized to Affymetrix Mouse 430A 2.0 gene chips.
Project description:Intracellular pathogens including the apicomplexan and opportunistic parasite Toxoplasma gondii profoundly modify their host cells in order to establish infection. We have shown previously that intracellular T. gondii inhibit up-regulation of regulatory and effector functions in murine macrophages (MΦ) stimulated with interferon (IFN)-γ, which is the cytokine crucial for controlling the parasites’ replication. Using genome-wide transcriptome analysis we show herein that infection with T. gondii leads to global unresponsiveness of murine macrophages to IFN-γ. More than 61% and 89% of the transcripts, which were induced or repressed by IFN-γ in non-infected MΦ, respectively, were not altered after stimulation of T. gondii-infected cells with IFN-γ. These genes are involved in a variety of biological processes, which are mostly but not exclusively related to immune responses. Analyses of the underlying mechanisms revealed that IFN-γ-triggered nuclear translocation of STAT1 still occurred in Toxoplasma-infected MΦ. However, STAT1 bound aberrantly to oligonucleotides containing the IFN-γ-responsive gamma-activated site (GAS) consensus sequence. Conversely, IFN-γ did not induce formation of active GAS-STAT1 complexes in nuclear extracts from infected MΦ. Mass spectrometry of protein complexes bound to GAS oligonucleotides showed that T. gondii-infected MΦ are unable to recruit non-muscle actin to IFN-γ-responsive DNA sequences, which appeared to be independent of stimulation with IFN-γ and of STAT1 binding. IFN-γ-induced recruitment of BRG-1 and acetylation of core histones at the IFN-γ-regulated CIITA promoter IV, but not β-actin was diminished by >90% in Toxoplasma-infected MΦ as compared to non-infected control cells. Remarkably, treatment with histone deacetylase inhibitors restored the ability of infected macrophages to express the IFN-γ regulated genes H2-A/E and CIITA. Taken together, these results indicate that Toxoplasma-infected MΦ are unable to respond to IFN-γ due to disturbed chromatin remodelling, but can be rescued using histone deacetylase inhibitors. Comparison of 4 different RNA pools with a 2-Color-Loop Design including 10 microarrays: [1] T. gondii infected and IFN-gamma treated, [2] T. gondii infected and untreated, [3] Non-infected and IFN-gamma treated, and [4] Non-infected and untreated.
Project description:To study the effect of stress on macrophages due to Toxoplasma, we stimulated murine bone marrow-derived macrophages (BMDMs) with IFN-γ (no-stimulate control) and infected them with the apicomplexan parasite Toxoplasma gondii. scRNA-Seq (10X Chromium genomics ) was performed to understand the changes in the immune cells and study the impact of the parasite.
Project description:Intracellular pathogens including the apicomplexan and opportunistic parasite Toxoplasma gondii profoundly modify their host cells in order to establish infection. We have shown previously that intracellular T. gondii inhibit up-regulation of regulatory and effector functions in murine macrophages (MΦ) stimulated with interferon (IFN)-γ, which is the cytokine crucial for controlling the parasites’ replication. Using genome-wide transcriptome analysis we show herein that infection with T. gondii leads to global unresponsiveness of murine macrophages to IFN-γ. More than 61% and 89% of the transcripts, which were induced or repressed by IFN-γ in non-infected MΦ, respectively, were not altered after stimulation of T. gondii-infected cells with IFN-γ. These genes are involved in a variety of biological processes, which are mostly but not exclusively related to immune responses. Analyses of the underlying mechanisms revealed that IFN-γ-triggered nuclear translocation of STAT1 still occurred in Toxoplasma-infected MΦ. However, STAT1 bound aberrantly to oligonucleotides containing the IFN-γ-responsive gamma-activated site (GAS) consensus sequence. Conversely, IFN-γ did not induce formation of active GAS-STAT1 complexes in nuclear extracts from infected MΦ. Mass spectrometry of protein complexes bound to GAS oligonucleotides showed that T. gondii-infected MΦ are unable to recruit non-muscle actin to IFN-γ-responsive DNA sequences, which appeared to be independent of stimulation with IFN-γ and of STAT1 binding. IFN-γ-induced recruitment of BRG-1 and acetylation of core histones at the IFN-γ-regulated CIITA promoter IV, but not β-actin was diminished by >90% in Toxoplasma-infected MΦ as compared to non-infected control cells. Remarkably, treatment with histone deacetylase inhibitors restored the ability of infected macrophages to express the IFN-γ regulated genes H2-A/E and CIITA. Taken together, these results indicate that Toxoplasma-infected MΦ are unable to respond to IFN-γ due to disturbed chromatin remodelling, but can be rescued using histone deacetylase inhibitors.
Project description:Human fibroblasts were infected or not with Toxoplasma gondii (Pru strain) for 18 h at a nominal MOI of 3. Cells were subsequently treated with human recombinant interferon gamma (0.5 ng/ml = 30 pM) for 0, 2, 4 and 8 h before RNA was harvested for cDNA microarray experiments. Uninfected samples were named N0, N2, N4 and N8 (i.e., N2 indicated uninfected cells treated with interferon gamma for 2 h); infected samples were named P0, P2, P4 and P8. Duplicate cultures were analyzed for each condition (indicated as "a" and "b"). The reference channel (ch1, green) contained Universal Human Reference RNA. Using a genome-wide microarray analysis we show here a complete dysregulation of interferon-gamma-inducible gene expression in human fibroblasts infected with Toxoplasma. Notably, 46 of the 127 interferon-gamma-responsive genes were induced and 19 were suppressed in infected cells before they were exposed to interferon gamma, indicating that other stimuli produced during infection may also regulate these genes. Following interferon-gamma treatment, none of the 127 interferon-gamma-responsive genes could be significantly induced in infected cells. Groups of assays that are related as part of a time series. Infection: Toxoplasma gondii (18h post-infection) Time: time of IFN-gamma treatment Growth Condition: interferon gamma Keywords: time_series_design
Project description:Human fibroblasts were infected or not with Toxoplasma gondii (Pru strain) for 18 h at a nominal MOI of 3. Cells were subsequently treated with human recombinant interferon gamma (0.5 ng/ml = 30 pM) for 0, 2, 4 and 8 h before RNA was harvested for cDNA microarray experiments. Uninfected samples were named N0, N2, N4 and N8 (i.e., N2 indicated uninfected cells treated with interferon gamma for 2 h); infected samples were named P0, P2, P4 and P8. Duplicate cultures were analyzed for each condition (indicated as "a" and "b"). The reference channel (ch1, green) contained Universal Human Reference RNA. Using a genome-wide microarray analysis we show here a complete dysregulation of interferon-gamma-inducible gene expression in human fibroblasts infected with Toxoplasma. Notably, 46 of the 127 interferon-gamma-responsive genes were induced and 19 were suppressed in infected cells before they were exposed to interferon gamma, indicating that other stimuli produced during infection may also regulate these genes. Following interferon-gamma treatment, none of the 127 interferon-gamma-responsive genes could be significantly induced in infected cells.
Project description:The closely related protozoan parasites Toxoplasma gondii and Neospora caninum display similar life cycles, subcellular ultrastructure, invasion mechanisms, metabolic pathways, and genome organization, but differ in their host range and disease pathogenesis. Type II (γ) interferon has long been known to be the major mediator of innate and adaptive immunity to Toxoplasma infection, but genome-wide expression profiling of infected host cells indicates that Neospora is a potent activator of the type I (α/β) interferon pathways typically associated with antiviral responses. Infection of macrophages from mice with targeted deletions in various innate sensing genes demonstrates that host responses to Neospora are dependent on the toll-like receptor Tlr3 and the adapter protein Trif. Consistent with this observation, RNA from Neospora elicits type I interferon responses when targeted to the host endo-lysosomal system. While live Toxoplasma fails to induce type I interferon, heat-killed parasites do trigger this response, and co-infection studies reveal that T. gondii actively suppresses the production of type I interferon. These findings reveal that eukaryotic pathogens can be potent inducers of type I interferon and that some parasite species, like Toxoplasma gondii, have evolved mechanisms to suppress this response. Human foreskin fibroblasts (HFF; line BJ-5ta) were cultured to confluency in T25 flasks, infected with one representative of each of the three architypial strains of Toxoplasma gondii: GT1 (type I), Prugniaud (type II) and VEG (type III), or the closely related parasite species, Neospora caninum (strain Nc-Liv). RNA was collected from biological replicates for expression profiling by microarray. Uninfected HFF cells were used as a reference.
Project description:Pre-infection with Toxoplasma parasites inhibits induction of an interferon gamma responsive gene expression program. In this study we aimed to determine what role host negative regulatory proteins that are induced by Toxoplasma infection, such as SOCS-1, have in this inhibition. We used Affymetrix microarrays to analyze host cell transcription after pre-treatment with the protein synthesis inhibitor cyclohexamide (CHX), Toxoplasma infection, and subsequent interferon-gamma stimulation. Human foreskin fibroblasts (HFFs) were left untreated or treated with CHX for 40min. Cells were infected, or not, with type I (RH) Toxoplasma parasites, for one hour, and subsequently stimulated with human IFN-γ for one hour. Total RNA was isolated and hybridized to Affymetrix Human U133A 2.0 gene chips.
Project description:The closely related protozoan parasites Toxoplasma gondii and Neospora caninum display similar life cycles, subcellular ultrastructure, invasion mechanisms, metabolic pathways, and genome organization, but differ in their host range and disease pathogenesis. Type II (?) interferon has long been known to be the major mediator of innate and adaptive immunity to Toxoplasma infection, but genome-wide expression profiling of infected host cells indicates that Neospora is a potent activator of the type I (?/?) interferon pathways typically associated with antiviral responses. Infection of macrophages from mice with targeted deletions in various innate sensing genes demonstrates that host responses to Neospora are dependent on the toll-like receptor Tlr3 and the adapter protein Trif. Consistent with this observation, RNA from Neospora elicits type I interferon responses when targeted to the host endo-lysosomal system. While live Toxoplasma fails to induce type I interferon, heat-killed parasites do trigger this response, and co-infection studies reveal that T. gondii actively suppresses the production of type I interferon. These findings reveal that eukaryotic pathogens can be potent inducers of type I interferon and that some parasite species, like Toxoplasma gondii, have evolved mechanisms to suppress this response. In vitro cultures of bone marrow-derived macrophages from WT or IFNAR2-/- mice were infected with either Toxoplasma gondii (VEG strain) or Neospora caninum (Nc2 strain) for 17 hours. RNA was collected from biological replicates for expression profiling by microarray. Uninfected controls for both WT and IFNAR2-/- were used as a reference.