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 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
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 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. 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 µl of pyrogen-free PBS. Sham-infected mice were administered 15 µl 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:Adaptive immunity is generated in lymphoid organs, but how these structures defend themselves during infection in humans is unknown. The nasal epithelium is a major site of viral entry, with adenoid nasal-associated lymphoid tissue (NALT) generating early adaptive responses. Here, using a nasopharyngeal biopsy technique, we investigated longitudinal immune responses in NALT following viral challenge, using SARS-CoV-2 infection as a natural experimental model. In acute infection, infiltrating monocytes formed a subepithelial and peri-follicular shield, recruiting NET-forming neutrophils, whilst tissue macrophages expressed pro-repair molecules during convalescence to promote the restoration of tissue integrity. Germinal centre B cells expressed anti-viral transcripts that inversely correlated with fate-defining transcription factors. Among T cells, tissue-resident memory CD8 T cells alone showed clonal expansion and maintained cytotoxic transcriptional programmes into convalescence. Together our study provides unique insights into how human nasal adaptive immune responses are generated and sustained in the face of viral challenge.
Project description:Nasal vaccination elicits a humoral immune response that provides protection from airborne pathogens, yet the origins and specific immune niches of antigen-specific IgA-secreting cells in the upper airways remain unknown. Here, we define glandular acinus structures of the nasal turbinates as an immunological niche that recruits IgA-secreting plasma cells from the nasal-associated lymphoid tissues (NALT) in response to intranasal vaccination. Using intact organ imaging, we investigated the cellular events that support antibody-mediated immune responses in the mouse upper airways. Through visualization of antigen-specific T and B cells in the upperairways, we demonstrate that nasal vaccination induced extensive B cell expansion in the subepithelial dome (SED) of the NALT, followed by invasion into commensal bacteria-driven chronic germinal centers (GCs) in a T cell-dependent manner. Antigen-specific B cell response in the NALT required pre-expansion of cognate T cells, which initiate the immune response in the inter-follicular regions of the NALT, and occurred effectively in the presence of Monophosphoryl-Lipid A (MPLA), a synthetic, non-toxic TLR-4 agonist. NALT ablation and blockade of PSGL-1 demonstrated that intranasal vaccination generates IgA+ plasma cells that home to the nasal turbinates through the blood circulation where they are positioned primarily around glandular acinus structures. Thus, the glandular part of the nasal turbinate is an immunological niche that hosts NALT-derived IgA-secreting cells. These cellular events can be manipulated to design vaccines against inhaled pathogens or in the treatment of upper airway allergic responses.
Project description:Nasal vaccination elicits a humoral immune response that provides protection from airborne pathogens, yet the origins and specific immune niches of antigen-specific IgA-secreting cells in the upper airways remain unknown. Here, we define glandular acinus structures of the nasal turbinates as an immunological niche that recruits IgA-secreting plasma cells from the nasal-associated lymphoid tissues (NALT) in response to intranasal vaccination. Using intact organ imaging, we investigated the cellular events that support antibody-mediated immune responses in the mouse upper airways. Through visualization of antigen-specific T and B cells in the upper airways, we demonstrate that nasal vaccination induced extensive B cell expansion in the subepithelial dome (SED) of the NALT, followed by invasion into commensal bacteria-driven chronic germinal centers (GCs) in a T cell-dependent manner. Antigen-specific B cell response in the NALT required pre-expansion of cognate T cells, which initiate the immune response in the inter-follicular regions of the NALT, and occurred effectively in the presence of Monophosphoryl-Lipid A (MPLA), a synthetic, non-toxic TLR-4 agonist. NALT ablation and blockade of PSGL-1 demonstrated that intranasal vaccination generates IgA+ plasma cells that home to the nasal turbinates through the blood circulation where they are positioned primarily around glandular acinus structures. Thus, the glandular part of the nasal turbinate is an immunological niche that hosts NALT-derived IgA-secreting cells. These cellular events can be manipulated to design vaccines against inhaled pathogens or in the treatment of upper airway allergic responses.
Project description:The transcriptomic innate immune response derived from human nasal epithelial cells depends on how Streptococcus pneumoniae colonises the nasopharynx. This study compared three wild type strains and one deficient in pneumolysin to explore the pathways of epithelial activation following a three hour infection in vitro.
Project description:Streptococcus pyogenes (Group A Streptococcus: GAS) is a major human pathogen that causes streptococcal pharyngitis, skin and soft-tissue infections, and life-threatening conditions such as streptococcal toxic shock syndrome (STSS). A large number of virulence-related genes are encoded on GAS genomes, which are involved in host-pathogen interaction, colonization, immune invasion, and long-term survival within hosts, causing the diverse symptoms. Here, we investigated the interaction between GAS-derived extracellular vesicles and host cells in order to reveal pathogenicity mechanisms induced by GAS infection.
Project description:Streptococcus pyogenes is an obligate human pathobiont associated with many disease states. Here, we present a novel model of S. pyogenes infection using intact murine epithelium. From this model, we were able to perform RNA sequencing to evaluate the genetic changes undertaken by both the bacterium and host at 5 and 24 hours post infection. Analysis of these genomic data demonstrate that S. pyogenes undergoes significant genetic adaptation to successfully infect the murine epithelium, including changes to metabolism and activation of the Rgg2/Rgg3 quorum sensing (QS) system. Subsequent experiments demonstrate that an intact Rgg2/Rgg3 QS cascade is necessary to establish a stable superficial skin infection. Furthermore, activation of this pathway results in increased murine morbidity and increased bacterial burden on the skin. This phenotype is associated with gross changes to the murine skin, as well as histopathological evidence of inflammation. Taken together, these experiments offer a novel method to investigate S. pyogenes-epithelial interactions and demonstrate that a well-studied QS pathway is critical to a persistent infection.
Project description:The nasal mucosa is frequently the initial site of respiratory viral infection, replication, and transmission, but the cellular composition at homeostasis, during infection, and during a memory response are poorly understood. Here, we generated a single-cell RNA-sequencing (scRNA-seq) atlas of the murine nasal mucosa sampling three distinct regions before and during primary and secondary influenza A virus (IAV) infection. Primary infection was largely restricted to respiratory mucosa and induced stepwise changes in immune and epithelial cell type, subset, and state composition over time. Following viral clearance (14 dpi), rare, previously undescribed Krt13+ nasal immune-interacting floor epithelial (KNIIFE) cells expressing multiple genes with immune communication potential increased concurrently with tissue-resident memory T (TRM)-like cells and early IgG+/IgA+ plasmablasts. Proportionality analysis coupled with cell-cell communication inference, alongside validation by in situ microscopy, underscored the CXCL16–CXCR6 signaling axis between MDMs and effector CD8 T cells 8dpi and KNIIFE cells and TRM cells 14 dpi. Secondary influenza challenge with a homologous or heterologous strain administered 60 dpi induced an accelerated and coordinated myeloid and lymphoid response without epithelial proliferation, illustrating how tissue-scale memory to natural infection engages both myeloid and lymphoid cells to reduce epithelial regenerative burden. Raw and processed single-cell counts matrices can be accessed and downloaded from the Broad Institute Single-Cell Portal from studies SCP2216 and SCP 2221.
Project description:The nasopharynx and the skin are the major oxygen-rich anatomical sites for colonization by the human pathogen Streptococcus pyogenes (group A Streptococcus, GAS). To establish infection, GAS must survive oxidative stress generated during aerobic metabolism and the release of reactive oxygen species (ROS) by host innate immune cells. Glutathione is the major host antioxidant molecule while GAS is glutathione-auxotrophic. Here we report the molecular characterization of the ABC transporter substrate binding protein GshT in the GAS glutathione salvage pathway. We demonstrate that glutathione uptake is critical for aerobic growth of GAS and that impaired import of glutathione induces oxidative stress that triggers enhanced production of the reducing equivalent NADPH. Our results highlight the interrelationship between glutathione assimilation, carbohydrate metabolism, virulence factor production and innate immune evasion. Together, these findings suggest an adaptive strategy employed by extracellular bacterial pathogens to exploit host glutathione stores for their own benefit.