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Innate immune response of murine nasal-associated lymphoid tissue (NALT) to Streptococcus pyogenes infection.

ABSTRACT: Streptococcus pyogenes is a major causative agent of tonsillitis or pharyngitis in children, which can lead to more invasive infections and noninfectious sequellae. S. pyogenes can persist in tonsils, while one-third of children treated with antibiotics continue to shed streptococci and have recurrent infections. Mouse nasal-associated lymphoid tissue (NALT) is functionally analogous to human oropharangeal lymphoid tissues. The innate immune responses of naïve cells from a mucosal site to S. pyogenes is not well described; therefore, we infected C57BL/6 mice intranasally with 108 CFU S. pyogenes. Transcriptional responses by NALT after S. pyogenes infection were analyzed by Affymetrix microarray and quantitative RT-PCR. Wild-type S. pyogenes induces transcription of both type I and IFN-gamma-responsive genes, pro-inflammatory genes, and acute phase response plasma proteins within 24h after infection. Invasion of NALT and the induction of the interferon response were not dependent on expression of anti-phagocytic M1 protein. However, infection with an attenuated, less invasive mutant indicated that a robust innate response by NALT is significantly influenced by intra-NALT bacterial load. Granulocytic populations of NALT, cervical lymph nodes and spleen were discriminated by characteristic surface and intracellular markers. Intranasal infection induces systemic release of neutrophils and a substantial influx of neutrophils into NALT at 24h, which decline by 48h after infection. Macrophages do not significantly increase in S. pyogenes-infected NALT. Intranasal infection of IFN-gamma -/- (GKO) C57BL/6 mice did not lead to systemic dissemination of wild type S. pyogenes, despite reduced expression of IFN-gamma-responsive mRNAs in NALT. Infected GKO mice had an unregulated influx of neutrophils into NALT compared to immunocompetant mice and mice treated with an anti-IFN-gamma antibody more rapidly cleared S. pyogenes from NALT. Thus, IFN-gamma-induced responses have a suppressive influence on early clearance of this pathogen from NALT. Keywords: disease state analysis

ORGANISM(S): Mus musculus

PROVIDER: GSE11494 | GEO | 2009/07/01

SECONDARY ACCESSION(S): PRJNA106309

REPOSITORIES: GEO

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Project description:Streptococcus pyogenes is a major causative agent of tonsillitis or pharyngitis in children, which can lead to more invasive infections and noninfectious sequellae. S. pyogenes can persist in tonsils, while one-third of children treated with antibiotics continue to shed streptococci and have recurrent infections. Mouse nasal-associated lymphoid tissue (NALT) is functionally analogous to human oropharangeal lymphoid tissues. The innate immune responses of naÃ¯ve cells from a mucosal site to S. pyogenes is not well described; therefore, we infected C57BL/6 mice intranasally with 108 CFU S. pyogenes. Transcriptional responses by NALT after S. pyogenes infection were analyzed by Affymetrix microarray and quantitative RT-PCR. Wild-type S. pyogenes induces transcription of both type I and IFN-gamma-responsive genes, pro-inflammatory genes, and acute phase response plasma proteins within 24h after infection. Invasion of NALT and the induction of the interferon response were not dependent on expression of anti-phagocytic M1 protein. However, infection with an attenuated, less invasive mutant indicated that a robust innate response by NALT is significantly influenced by intra-NALT bacterial load. Granulocytic populations of NALT, cervical lymph nodes and spleen were discriminated by characteristic surface and intracellular markers. Intranasal infection induces systemic release of neutrophils and a substantial influx of neutrophils into NALT at 24h, which decline by 48h after infection. Macrophages do not significantly increase in S. pyogenes-infected NALT. Intranasal infection of IFN-gamma -/- (GKO) C57BL/6 mice did not lead to systemic dissemination of wild type S. pyogenes, despite reduced expression of IFN-gamma-responsive mRNAs in NALT. Infected GKO mice had an unregulated influx of neutrophils into NALT compared to immunocompetant mice and mice treated with an anti-IFN-gamma antibody more rapidly cleared S. pyogenes from NALT. Thus, IFN-gamma-induced responses have a suppressive influence on early clearance of this pathogen from NALT. Experiment Overall Design: C57BL/6 mice (6-10 weeks old), 4 per group, were infected intranasally with log-phase Streptococcus pyogenes, 2 to 4 x 10^8 CFU per 15 Âµl of pyrogen-free PBS. Sham-infected mice were administered 15 Âµl of the same PBS. Mice were infected with wild type strain 90-226 (Cue 1998), a 90-226 strain containing an in-frame deletion of M1 protein (90-226 delta emm1) (Zimmerlein 2005) or an attenuated 90-226 which lacks both M1 and SCPA proteins (90-226att). NALT was collected from mice at 24h after infection and stored in RNAlater until RNA could be purified).

Project description:To investigate the early host response triggered by three different strains of Trypanosoma cruzi at a local infection site, changes in host gene expression were monitored in a murine intradermal infection model using Affymetrix oligonucleotide arrays. Robust induction of IFN-stimulated genes (ISGs) was observed in excised skin 24 hours post-infection where the level of ISG induction was parasite strain-dependent with the least virulent strain triggering a muted IFN response. Infection of mice immunodepleted of IFNÎ³-producing cells or infection of IFNÎ³-deficient mice had minimal impact on the IFN response generated in T. cruzi infected mice. In contrast, infection of mice lacking the type I IFN receptor demonstrated that type I IFNs are largely responsible for the IFN response generated at the site of infection. These data highlight type I IFNs as important components of the innate immune response to T. cruzi the site of inoculation and their role in shaping the early transcriptional response to this pathogen. We used microarrays to detail the local host transcriptional response to intradermal T. cruzi infection in WT mice and mice depleted of NK cells, or deficient in IFN-gamma or type I IFN responses. Additionally we compared the local host-transcriptional response generated to infection with 3 different strains of Trypanosoma cruzi (Y, Brazil, and G). Experiment Overall Design: Mice were infected by intradermal injection of 10^6 T. cruzi trypomastigotes in 100uL of saline split between 2 adjacent sites on the shaved side flank. Control mice were injected with an equal volume of saline. 24 hours post-injection approximately 75mm^2 of skin immediately surrounding the injection site was excised and RNA was isolated from the tissue. Balb/c mice were used for most experiments and IFN-gamma KO mice were on the Balb/c background. WT 129 mice were also used as IFNAR-/- mice were on the 129 background. In total 33 arrays were performed. 7 WT (Balb/c) control, 3 Y strain infected, 3 Brazil strain infected, 3 G strain infected, 2 IFN-gamma KO control, 2 IFN-gamma KO infected, 1 NK cell depleted control, 1 NK cell depleted infected, 3 WT (129) control, 3 WT (129) infected, 3 IFNAR KO control, 3 IFNAR KO infected

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.

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Innate immune response of murine nasal-associated lymphoid tissue (NALT) to Streptococcus pyogenes infection.

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