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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:Interferon-gamma (IFN-gamma) is approved as a drug to treat chronic granulomatous disease and osteopetrosis and is also used in hyperimmunoglobulin E syndromes. These primary immunodeficiencies involve defects in neutrophils/polymorphonuclear cells. Neutrophils mature in the bone marrow and then enter the blood where they quickly undergo apoptotic cell death with a half-life of 5-10 hours. Therefore we reasoned that IFN-gamma might exert its effects on neutrophils via prolonged exposure to cells undergoing maturation toward a terminally differentiated state in the marrow rather than by its brief exposure to short-lived circulating cells. To explore this possibility we made use of PLB-985 cells which are a myeloblast-like myeloid cell line that can be differentiated into a mature, neutrophil-like state by treatment with various agents including DMSO. In initial studies we investigated transcription and protein expression in PLB-985 cells undergoing DMSO-mediated maturation in the presence or absence of IFN-gamma and identified several classes of immunity related genes that were differentially expressed in the presence of the drug and could potentially explain the immune supportive properties of IFN-gamma. Next we explored if the effect of IFN-gamma on expression of these genes is dependent on whether the cells are undergoing maturation; to do this we compared the effects of IFN-gamma on cells cultured with and without DMSO. For a subset of genes the expression level changes caused by IFN-gamma were much greater in maturing cells than non-maturing cells. These findings indicate that developmental changes associated with cell maturation can modulate the effects of IFN-gamma and supports our hypothesis that the effects of the drug on developing neutrophils in the bone marrow may be very different from its effects on mature cells in the blood. We also compared the effects on gene expression of applying IFN-gamma either during DMSO mediated PLB-985 cell maturation or after maturation i.e. IFN-gamma was applied to already mature cells. For some genes we found that IFN-gamma applied to mature cells caused large changes in expression similar to those seen when IFN-gamma was applied during maturation, however for other genes no effect was seen when drug was applied to mature cells but large effects were seen when drug was applied during DMSO treatment. This data suggests that, in the former class of genes, the effects of IFN-gamma application during maturation are largely the result of the effects of the drug on cells approaching full maturity but in the latter class of genes the effects of IFN-gamma only become apparent when it is present throughout maturation. This further supports our hypothesis that the effects of IFN-gamma are modulated by developmental changes associated with cell maturation.

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

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