Interferon-γ Production by Neutrophils during Bacterial Pneumonia in Mice

Center for Airways Disease, Department of Medicine, University of North Carolina, Chapel Hill, NC 27599-7248, USA.
American Journal of Respiratory and Critical Care Medicine (Impact Factor: 13). 12/2010; 183(10):1391-401. DOI: 10.1164/rccm.201004-0592OC
Source: PubMed


Neutrophils are usually the first circulating leukocytes to respond during bacterial pneumonia. Their expression of oxidants, proteases, and other mediators present in granules is well documented, but their ability to produce mediators through transcription and translation after migration to an inflammatory site has been appreciated only more recently. Interferon (IFN)-γ is a cytokine with many functions important in host defense and immunity.
To examine the expression and function of IFN-γ in bacterial pneumonias.
IFN-γ mRNA and protein were measured in digests of mouse lungs with 24-hour bacterial pneumonia. Bacterial clearance was studied with IFN-γ-deficient mice.
Streptococcus pneumoniae and Staphylococcus aureus each induce expression of IFN-γ mRNA and protein by neutrophils by 24 hours. Only neutrophils that have migrated into pneumonic tissue produce IFN-γ. Deficiency of Hck/Fgr/Lyn, Rac2, or gp91(phox) prevents IFN-γ production. IFN-γ enhances bacterial clearance and is required for formation of neutrophil extracellular traps. In contrast, Pseudomonas aeruginosa and Escherichia coli induce production of IFN-γ mRNA but not protein. During pneumonia induced by E. coli but not S. pneumoniae, neutrophils produce microRNAs that target the 3' untranslated region of the IFN-γ gene.
S. pneumoniae and S. aureus, but not P. aeruginosa and E. coli, induce emigrated neutrophils to produce IFN-γ within 24 hours. Hck/Fgr/Lyn, Rac2, and NADPH oxidase are required for IFN-γ production. IFN-γ facilitates bacterial clearance at least in part through regulating formation of neutrophil extracellular traps. Differential expression by neutrophils of microRNAs that target the 3' untranslated region of the IFN-γ gene may contribute to the pathogen-specific regulation of translation.

Download full-text


Available from: Dirk P Dittmer
  • Source
    • "Microorganism MiRNA Targets Host Cell type/tissue Function References Gram negative Escherichia coli N/A IFN-g Mus musculus Lungs Innate immunity [77] Francisella tularensis miR-155 SHIP Homo sapiens Monocytes and macrophages Inflammation [78] Gram negative bacteria (LPS) miR-1224 Sp1 and TNF-a Mus musculus Spleen, kidney, lung, RAW267.4 cells Cytokine signalling [79] Gram negative bacteria (LPS) miR-221; miR-579; miR-125b TNF-a Mus musculus Whole organism Cytokine signalling [80] Helicobacter pylori miR-449 GMNN, MET, CCNE2 and SIRT1 Homo sapiens, Mus musculus Human gastric tumours and mouse gastric tissues Cell proliferation [81] Helicobacter pylori miR-1; miR-133 HD4, SRF Mus musculus Mouse stomach Pathogenesis of the disease and cell proliferation [82] Helicobacter pylori miR-146a IRAK1, TRAF6 Homo sapiens Gastric epithelial cells and gastric mucosal tissues Inflammation [83] Helicobacter pylori miR-223 N/A Homo sapiens Gastric mucosa and gastric epithelium Inflammation [84] Helicobacter pylori miR-155 MyD88 Homo sapiens Gastric cancer cell line AGS Inflammation [85] Helicobacter pylori miR-155 PKIa Homo sapiens T cells Inflammation [86] Helicobacter pylori miR-218 ECOP Homo sapiens Gastric cancer cell line AGS Inflammation [87] Helicobacter pylori miR-155 IL-8, GRO-a Homo sapiens Gastric epithelial cells and gastric mucosal tissues Inflammation [88] Helicobacter pylori miR-124a-1; miR-124a-2; miR-124a-3 N/A Homo sapiens Gastric mucosa Pathogenesis of the disease [23] Helicobacter pylori miR-21 RECK Homo sapiens Gastric cancer tissues and AGS cell line Pathogenesis of the disease [24] Salmonella typhimurium let-7 IL-6 and IL-10 Mus musculus Macrophages and epithelial cells Cytokine signalling [89] Wolbachia pipientis miR-2940 Metallo-protease Aedes aegypti Whole organism and cell lines Colonization of the host [90] "
    [Show abstract] [Hide abstract]
    ABSTRACT: MicroRNAs are a class of small non-coding RNAs that have emerged as key regulators of gene expression at the post-transcriptional level by sequence-specific binding to target mRNAs. Some microRNAs block translation, while others promote mRNA degradation, leading to a reduction in protein availability. A single miRNA can potentially regulate the expression of multiple genes and their encoded proteins. Therefore, miRNAs can influence molecular signalling pathways and regulate many biological processes in health and disease. Upon infection, host cells rapidly change their transcriptional programs, including miRNA expression, as a response against the invading microorganism. Not surprisingly, pathogens can also alter the host miRNA profile to their own benefit, which is of major importance to scientists addressing high morbidity and mortality infectious diseases such as tuberculosis. In this review, we present recent findings on the miRNAs regulation of the host response against mycobacterial infections, providing new insights into host-pathogen interactions. Understanding these findings and its implications could reveal new opportunities for designing better diagnostic tools, therapies and more effective vaccines.
    Full-text · Article · Dec 2015
  • Source
    • "Interferon-γ has been shown to modulate many aspects of in vitro neutrophil functions [41] [42] [43]. Williams et al. [44] showed that IFN-γ protects against the development of structural damage in experimental arthritis by regulating neutrophil influx into diseases joints and in vitro studies using fibroblast-like synoviocytes, IFN-γ modulated both IL-1β and TNF-α, resulting in the down-regulation of chemokine CXCL-8. "
    [Show abstract] [Hide abstract]
    ABSTRACT: Here, we investigated the ability of IFN-γ to modulate the functions of mouse neutrophils in vitro. Neutrophils incubated in the presence of IFN-γ showed enhanced phagocytosis in response to zymosan, opsonized zymosan or precipitated immune complexes of IgG and ovalbumin. The effect of IFN-γ was dose-dependent with an initial response at 10U/ml and a maximal response at 150U/ml; 2h of incubation were required to reach the optimal response level. These stimuli can also induce IFN-γ-pretreated neutrophils to release reactive oxygen species (ROS), such as superoxide anion, hydrogen peroxide and hypochlorous acid, as well as granule lysosomal enzymes and the pro-inflammatory cytokines TNF-α and IL-6. We found that increased expression of FcγR, dectin-1 and complement receptors (CRs) correlated with these effects in these cells. The enhancing effect of IFN-γ on the respiratory burst was found to be associated with up-regulation of the gp91(phox) and p47(phox) subunits of NADPH oxidase, as measured by their mRNA levels. The enhancing effect of IFN-γ on phagocytosis and ROS release may not only be relevant for the efficient killing of invading microorganisms, but may also produce oxidative stress on adjacent cells, resulting in a possible inflammatory role that could also be favored by the liberation of the pro-inflammatory cytokines TNF-α and IL-6.
    Full-text · Article · Dec 2013 · International immunopharmacology
  • Source
    • "Single lung cells from mice were isolated as previously described with some modifications [18]. Briefly, mice received an overdose of inhaled halothane, and their lungs were perfused with PBS via the right ventricles. "
    [Show abstract] [Hide abstract]
    ABSTRACT: The excess and persistent accumulation of fibroblasts due to aberrant tissue repair results in fibrotic diseases such as idiopathic pulmonary fibrosis. Recent reports have revealed significant changes in microRNAs during idiopathic pulmonary fibrosis and evidence in support of a role for microRNAs in myofibroblast differentiation and the epithelial-mesenchymal transition in the context of fibrosis. It has been reported that microRNA-21 is up-regulated in myofibroblasts during fibrosis and promotes transforming growth factor-beta signaling by inhibiting Smad7. However, expression changes in microRNA-21 and the role of microRNA-21 in epithelial-mesenchymal transition during lung fibrosis have not yet been defined. Lungs from saline- or bleomycin-treated C57BL/6 J mice and lung specimens from patients with idiopathic pulmonary fibrosis were analyzed. Enzymatic digestions were performed to isolate single lung cells. Lung epithelial cells were isolated by flow cytometric cell sorting. The expression of microRNA-21 was analyzed using both quantitative PCR and in situ hybridization. To induce epithelial-mesenchymal transition in culture, isolated mouse lung alveolar type II cells were cultured on fibronectin-coated chamber slides in the presence of transforming growth factor-beta, thus generating conditions that enhance epithelial-mesenchymal transition. To investigate the role of microRNA-21 in epithelial-mesenchymal transition, we transfected cells with a microRNA-21 inhibitor. Total RNA was isolated from the freshly isolated and cultured cells. MicroRNA-21, as well as mRNAs of genes that are markers of alveolar epithelial or mesenchymal cell differentiation, were quantified using quantitative PCR. The lung epithelial cells isolated from the bleomycin-induced lung fibrosis model system had decreased expression of epithelial marker genes, whereas the expression of mesenchymal marker genes was increased. MicroRNA-21 was significantly upregulated in isolated lung epithelial cells during bleomycin-induced lung fibrosis and human idiopathic pulmonary fibrosis. MicroRNA-21 was also upregulated in the cultured alveolar epithelial cells under the conditions that enhance epithelial-mesenchymal transition. Exogenous administration of a microRNA-21 inhibitor prevented the increased expression of vimentin and alpha-smooth muscle actin in cultured primary mouse alveolar type II cells under culture conditions that induce epithelial-mesenchymal transition. Our experiments demonstrate that microRNA-21 is increased in lung epithelial cells during lung fibrosis and that it promotes epithelial-mesenchymal transition.
    Full-text · Article · Sep 2013 · Respiratory research
Show more