Nuclear receptor 4A1 is Critical for Neutrophil-Dependent Pulmonary Immunity to Klebsiella pneumoniae Infection
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ABSTRACT:
ORGANISM(S): Mus musculus
PROVIDER: GSE290097 | GEO | 2025/03/25
REPOSITORIES: GEO
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Project description:Klebsiella pneumoniae (KP) are extracellular Gram-negative bacteria that cause infections in lower respiratory and urinary tract, and bloodstream. STAT1 is a master transcription factor that acts to maintain T-cell quiescence under homeostatic conditions. Although STAT1 helps defend against systemic spread of acute KP intrapulmonary infection, whether STAT1 regulation of T-cell homeostasis impacts pulmonary host defense during acute bacterial infection and injury is less clear. Using a clinical KP respiratory isolate and a pneumonia mouse model, we found STAT1-deficiency led to an early neutrophil-dominant transcriptional profile and neutrophil-recruitment in the lung preceding widespread bacterial dissemination and lung injury development. Yet, myeloid cell STAT1 was dispensable for control of KP proliferation and dissemination, as myeloid cell-specific STAT1-deficient (LysMCre/WT;Stat1fl/fl) mice showed similar bacterial burden in lung, liver, and kidney as WT littermates. Surprisingly, IL-17 producing CD4+ T-cells infiltrated Stat1-/- mice lungs early during KP infection. Increase in Th17-cells in the lung was not due to preexisting immunity against KP and were consistent with circulating rather than tissue-resident CD4+ T-cells. However, blocking global IL17 signaling with anti-IL17-RC administration led to increased proliferation and dissemination of KP, suggesting IL17 provided by other innate immune cells is essential in defense against KP. Contrastingly, depletion of CD4+ T-cells reduced Stat1-/- mice lung bacterial burden indicating early CD4+ T-cell activation in the setting of global STAT1-deficiency is pathogenic. Altogether, our findings suggest STAT1 employs myeloid cell-extrinsic mechanisms to regulate neutrophil responses and provide protection against invasive KP by restricting non-specific CD4+ T-cell activation and immunopathology in the lung.
2024-01-10 | GSE251767 | GEO
Project description:Klebsiella pneumoniae is an arising threat to human health. However, host immune responses in response to this bacterium remain to be elucidated. The goal of this study was to identify the dominant host immune responses associated with Klebsiella pneumoniae pulmonary infection. Pulmonary mRNA profiles of 6-8-weeks-old BALB/c mice infected with/without Klebsiella pneumoniae were generated by deep sequencing using Illumina Novaseq 6000. qRT–PCR validation was performed using SYBR Green assays. Using KEGG (Kyoto Encyclopedia of Genes and Genomes) analysis, we identified several immune associated pathways, including complement and coagulation cascades, Toll-like receptor signaling pathway, Rap1 signaling pathway, chemokine signaling pathway, TNF signaling pathway, phagosome and NOD-like receptor signaling pathway, were involved in Klebsiella pneumoniae pulmonary infection. Using ICEPOP (Immune CEll POPulation) analysis, we found that several cell types were involved in the host immune response to Klebsiella pneumoniae pulmonary infection, including dendritic cells, macrophages, monocytes, NK (natural killer) cells, stromal cells. Further, IL-17 chemokines were significantly increased during Klebsiella pneumoniae infection. This study provided evidence for further studying the pathogenic mechanism of Klebsiella pneumoniae pneumonia infection.
2021-03-30 | GSE171048 | GEO
Project description:Diabetes mellitus is associated with an increased risk of pneumonia, which is often caused by so-called typical and atypical pathogens including Streptoccocus pneumoniae and Legionella pneumophila, respectively. Here, we employed a varity of mouse models to investigate how diabetes influences pulmonary antibacterial immunity. Following intranasal infection with Streptoccocus pneumoniae or Legionella pneumphila, type 2 diabetic and prediabetic mice had higher bacterial loads in their lungs as compared to control animals. Single cell RNA sequencing, flow cytometry, and functional analyses revealed a compromised type II IFN (IFNg) production by natural killer cells in diabetic and prediabetic mice, which was linked to reduced IL-12 production by CD103+ dendritic cells. Treatment with IFNg rescued antibacterial defense against L. pneumophila but not against S. pneumoniae in diabetic animals, although impaired production of IFNg also contributed to the compromised anti-pneumococcal resistance in diabetic mice. These findings uncover a mechanism that could help to explain why type 2 diabetes predisposes to pneumonia. We establish proof of concept for host-directed treatment strategies to reinforce compromised IFNg-mediated antibacterial defense against atypical lung pathogens.
2024-11-19 | GSE270694 | GEO
Project description:Klebsiella pneumoniae is a major pathogen that causes a variety of human infections, posing a significant public health threat. Understanding its pathogenesis is essential for devising effective treatment strategies. In this study, we aim to identify critical virulence factors in K. pneumoniae through analyzing virulence-associated genes that were identified in three transposon mutagenesis libraries. Two genes, wzi and kvrB, are consistently detected across these libraries, indicating their potential as critical virulence factors. While Wzi has usually been implicated in virulence through CPS, its actual function in K. pneumoniae pathogenicity has rarely been explored. Wzi deficiency reduces CPS production in K. pneumoniae, contrasting with its effect in Escherichia coli. Importantly, Wzi exerts a pivotal role in K. pneumoniae pathogenicity in vitro and in vivo, functioning through both CPS-dependent and -independent pathways. Wzi inhibits the secretion of IFN-γ-related cytokines at early infection stage to promote K. pneumoniae survival in the host. Wzi triggers sustained neutrophil recruitment during infection through the upregulation of CXCL1 expression, resulting in the pulmonary barrier damage and increased K. pneumoniae invasion into the bloodstream. Concurrently, Wzi confers K. pneumoniae to counteract neutrophil-mediated clearance in a CPS-dependent manner. Sequence polymorphisms of wzi significantly affect bacterial resistance to serum killing, with alleles frequently associated with hypervirulent K. pneumoniae exhibiting the highest resistance. Collectively, our findings highlight that the dual role of Wzi as a CPS-dependent and -independent virulence factor that combats host clearance during K. pneumoniae infection, representing a promising target for the development of anti-infective treatment against the bug.
2025-02-25 | GSE286873 | GEO
Project description:Alveolar macrophages orchestrate pulmonary innate immunity and are essential for early immune surveillance and clearance of microorganisms in the airways. Inflammatory signaling must be sufficiently robust to promote host defense but limited enough to prevent excessive tissue injury. Macrophages in the lungs utilize multiple transcriptional and post-transcriptional mechanisms of inflammatory gene expression to delicately balance the elaboration of immune mediators. RNA terminal uridyltransferases (TUTs), including the closely homologous family members Zcchc6 (TUT7) and Zcchc11 (TUT4), have been implicated in the post-transcriptional regulation of inflammation from studies conducted in vitro. In vivo, we observed that Zcchc6 is expressed in mouse and human primary macrophages. Zcchc6-deficient mice are viable and born in Mendelian ratios and do not exhibit an observable spontaneous phenotype under basal conditions. Following an intratracheal challenge with S. pneumoniae, Zcchc6 deficiency led to a modest but significant increase in the expression of select cytokines including IL-6, CXCL1, and CXCL5. These findings were recapitulated in vitro whereby Zcchc6-deficient macrophages exhibited similar increases in cytokine expression due to bacterial stimulation. Although loss of Zcchc6 also led to increased neutrophil emigration to the airways during pneumonia, these responses were not sufficient to impact host defense against infection.
2017-08-17 | GSE98222 | GEO
Project description:Neutrophils are critical in the host defense against Staphylococcus aureus, a major human pathogen. However, even in the setting of a robust neutrophil response, S. aureus can cause persistent infection. Here we demonstrate that S. aureus impairs neutrophil function by triggering the production of the anti-inflammatory metabolite, itaconate. The enzyme that synthesizes itaconate, Irg1, is selectively expressed in neutrophils during S. aureus pneumonia. Itaconate inhibits neutrophil glycolysis and oxidative burst, which impairs survival and bacterial killing. In a murine pneumonia model, neutrophil Irg1 expression protects critical lung cell populations from oxidative stress but compromises bacterial clearance. S. aureus is thus able to evade innate immune clearance by targeting neutrophil metabolism and inducing the production of the antiinflammatory metabolite itaconate.
2023-01-01 | GSE215195 | GEO
Project description:Pulmonary innate immunity is required for host defense; however, excessive neutrophil inflammation can cause life-threatening acute lung injury. B lymphocytes can be regulatory, yet little is known about peripheral transitional IgM+ B cells in terms of regulatory properties. Using single cell RNA sequencing, we discovered eight IgM+ B cell subsets with unique gene regulatory networks in the lung circulation dominated by transitional type 1 (T1B) and 2 (T2B) B cells. Lung intravital confocal microscopy revealed that T2B marginate in the pulmonary capillaries via CD49e and required CXCL13 and CXCR5. During lung inflammation, marginated T2B dampened excessive neutrophil vascular inflammation via the specialized proresolving molecule lipoxin A4 (LXA4). Exogenous CXCL13 dampened excessive neutrophilic inflammation by increasing marginated B cells and LXA4 recapitulated neutrophil regulation in B-cell deficient mice during inflammation and fungal pneumonia. Thus, the lung microvasculature is enriched in multiple IgM+ B cell subsets with marginating capillary T2B that dampen neutrophil responses.
2021-07-19 | GSE156311 | GEO
Project description:Pneumonia is a serious problem worldwide. We recently demonstrated that innate defense mechanisms of the lung are highly inducible against pneumococcal pneumonia. To determine the breadth of protection conferred by stimulation of lung mucosal innate immunity, and to identify cells and signaling pathways activated by this treatment, mice were treated with an aerosolized bacterial lysate, then challenged with lethal doses of bacterial and fungal pathogens. Mice were highly protected against a broad array of Gram-positive, Gram-negative, and Class A bioterror bacterial pathogens, and Aspergillus fumigatus. Protection was associated with rapid pathogen killing within the lungs, and this effect was recapitulated in vitro using a respiratory epithelial cell line. Gene expression analysis of lung tissue showed marked activation of NF-kappa-B, Type I and II interferon, and antifungal Card9-Bcl10-Malt1 pathways. Cytokines were the most strongly induced genes, but the inflammatory cytokines TNF and IL-6 were not required for protection. Lung-expressed antimicrobial peptides were also highly upregulated. Taken together, stimulated innate resistance (StIR) appears to occur through the activation of multiple host defense signaling pathways in lung epithelial cells, inducing rapid pathogen killing, and conferring broad protection against virulent bacterial and fungal pathogens. Augmentation of innate antimicrobial defenses of the lungs might have therapeutic value for protection of patients with neutropenia or impaired adaptive immunity against opportunistic pneumonia, and for defense of immunocompetent subjects against a bioterror threat or epidemic respiratory infection. Keywords: Differential expression, innate immunity, pneumonia, immunocompromised host; lung epithelium, in vitro, MLE-15 cells were treated with sham (PBS), NTHi lysate (100 ug/ml) or EF2505-III (40 ug/ml). 4 unique samples per group. Treated for 2 hours. Hybridized to Illumina Sentrix Mouse-6 v1.1 Beadhips.
2010-06-24 | E-GEOD-13685 | biostudies-arrayexpress
Project description:Pneumonia is a serious problem worldwide. We recently demonstrated that innate defense mechanisms of the lung are highly inducible against pneumococcal pneumonia. To determine the breadth of protection conferred by stimulation of lung mucosal innate immunity, and to identify cells and signaling pathways activated by this treatment, mice were treated with an aerosolized bacterial lysate, then challenged with lethal doses of bacterial and fungal pathogens. Mice were highly protected against a broad array of Gram-positive, Gram-negative, and Class A bioterror bacterial pathogens, and Aspergillus fumigatus. Protection was associated with rapid pathogen killing within the lungs, and this effect was recapitulated in vitro using a respiratory epithelial cell line. Gene expression analysis of lung tissue showed marked activation of NF-kappaB, Type I and II interferon, and antifungal Card9-Bcl10-Malt1 pathways. Cytokines were the most strongly induced genes, but the inflammatory cytokines TNF and IL-6 were not required for protection. Lung-expressed antimicrobial peptides were also highly upregulated. Taken together, stimulated innate resistance (StIR) appears to occur through the activation of multiple host defense signaling pathways in lung epithelial cells, inducing rapid pathogen killing, and conferring broad protection against virulent bacterial and fungal pathogens. Augmentation of innate antimicrobial defenses of the lungs might have therapeutic value for protection of patients with neutropenia or impaired adaptive immunity against opportunistic pneumonia, and for defense of immunocompetent subjects against a bioterror threat or epidemic respiratory infection. Keywords: differential gene expression; time course; innate immunity; pneumonia; immunocompromised host; lung epithelium Gene expression patterns in mouse lung homogenates were analyzed 2h after exposure to aerosolized PBS (Sham treatment), 2h after exposure to aerosolized NTHi lysate or 4h after exposure to aerosolized NTHi lysate. Each group consisted of six mice.
2010-06-24 | E-GEOD-13740 | biostudies-arrayexpress
Project description:Pneumococcal pneumonia is a leading cause of death and a major source of human morbidity. The initial immune response plays a central role in determining the course and outcome of pneumococcal disease. We combine bacterial titer measurements from mice infected with Streptococcus pneumoniae with mathematical modeling to investigate the coordination of immune responses and the effects of initial inoculum on outcome. To evaluate the contributions of individual components, we systematically build a mathematical model from three subsystems that describe the succession of defensive cells in the lung: resident alveolar macrophages, neutrophils and monocyte-derived macrophages. The alveolar macrophage response, which can be modeled by a single differential equation, can by itself rapidly clear small initial numbers of pneumococci. Extending the model to include the neutrophil response required additional equations for recruitment cytokines and host cell status and damage. With these dynamics, two outcomes can be predicted: bacterial clearance or sustained bacterial growth. Finally, a model including monocyte-derived macrophage recruitment by neutrophils suggests that sustained bacterial growth is possible even in their presence. Our model quantifies the contributions of cytotoxicity and immune-mediated damage in pneumococcal pathogenesis.
2024-09-02 | BIOMD0000000924 | BioModels