Dataset Information

Central Role of the NF-?B Pathway in the Scgb1a1-Expressing Epithelium in Mediating Respiratory Syncytial Virus-Induced Airway Inflammation.

ABSTRACT: Lower respiratory tract infection with respiratory syncytial virus (RSV) produces profound inflammation. Despite an understanding of the role of adaptive immunity in RSV infection, the identity of the major sentinel cells initially triggering inflammation is controversial. Here we evaluate the role of nonciliated secretoglobin (Scgb1a1)-expressing bronchiolar epithelial cells in RSV infection. Mice expressing a tamoxifen (TMX)-inducible Cre recombinase-estrogen receptor fusion protein (CreERTM) knocked into the Scgb1a1 locus were crossed with mice that harbor a RelA conditional allele (RelAfl ), with loxP sites flanking exons 5 to 8 of the Rel homology domain. The Scgb1a1CreERTM/+ × RelAfl/fl mouse is a RelA conditional knockout (RelACKO) of a nonciliated epithelial cell population enriched in the small bronchioles. TMX-treated RelACKO mice have reduced pulmonary neutrophilic infiltration and impaired expression and secretion of NF-?B-dependent cytokines in response to RSV. In addition, RelACKO mice had reduced expression levels of interferon (IFN) regulatory factor 1/7 (IRF1/7) and retinoic acid-inducible gene I (RIG-I), components of the mucosal IFN positive-feedback loop. We demonstrate that RSV replication induces RelA to complex with bromodomain-containing protein 4 (BRD4), a cofactor required for RNA polymerase II (Pol II) phosphorylation, activating the atypical histone acetyltransferase (HAT) activity of BRD4 required for phospho-Ser2 Pol II formation, histone H3K122 acetylation, and cytokine secretion in vitro and in vivo TMX-treated RelACKO mice have less weight loss and reduced airway obstruction/hyperreactivity yet similar levels of IFN-? production despite higher levels of virus production. These data indicate that the nonciliated Scgb1a1-expressing epithelium is a major innate sensor for restricting RSV infection by mediating neutrophilic inflammation and chemokine and mucosal IFN production via the RelA-BRD4 pathway.IMPORTANCE RSV infection is the most common cause of infant hospitalizations in the United States, resulting in 2.1 million children annually requiring medical attention. RSV primarily infects nasal epithelial cells, spreading distally to produce severe lower respiratory tract infections. Our study examines the role of a nonciliated respiratory epithelial cell population in RSV infection. We genetically engineered a mouse that can be selectively depleted of the NF-?B/RelA transcription factor in this subset of epithelial cells. These mice show an impaired activation of the bromodomain-containing protein 4 (BRD4) coactivator, resulting in reduced cytokine expression and neutrophilic inflammation. During the course of RSV infection, epithelial RelA-depleted mice have reduced disease scores and airway hyperreactivity yet increased levels of virus replication. We conclude that RelA-BRD4 signaling in nonciliated bronchiolar epithelial cells mediates neutrophilic airway inflammation and disease severity. This complex is an attractive target to reduce the severity of infection.

SUBMITTER: Tian B

PROVIDER: S-EPMC5952137 | biostudies-other | 2018 Jun

REPOSITORIES: biostudies-other

ACCESS DATA

Publications

Central Role of the NF-κB Pathway in the <i>Scgb1a1</i>-Expressing Epithelium in Mediating Respiratory Syncytial Virus-Induced Airway Inflammation.

Tian Bing B Yang Jun J Zhao Yingxin Y Ivanciuc Teodora T Sun Hong H Wakamiya Maki M Garofalo Roberto P RP Brasier Allan R AR

Journal of virology 20180514 11

Lower respiratory tract infection with respiratory syncytial virus (RSV) produces profound inflammation. Despite an understanding of the role of adaptive immunity in RSV infection, the identity of the major sentinel cells initially triggering inflammation is controversial. Here we evaluate the role of nonciliated secretoglobin (<i>Scgb1a1</i>)-expressing bronchiolar epithelial cells in RSV infection. Mice expressing a tamoxifen (TMX)-inducible Cre recombinase-estrogen receptor fusion protein (Cr ...[more]

PMID: 29593031

Similar Datasets

Project description:The airway mucosa expresses protective interferon (IFN) and inflammatory cytokines in response to respiratory syncytial virus (RSV) infection. In this study, we examine the role of bromodomain containing 4 (BRD4) in mediating this innate immune response in human small airway epithelial cells. We observe that RSV induces BRD4 to complex with NF-κB/RelA. BRD4 is functionally required for expression of the NF-κB-dependent inflammatory gene regulatory network (GRN), including the IFN response factor 1 (IRF1) and IRF7, which mediate a cross talk pathway for RIG-I upregulation. Mechanistically, BRD4 is required for cyclin-dependent kinase 9 (CDK9) recruitment and phospho-Ser 2 carboxy-terminal domain (CTD) RNA polymerase (Pol) II formation on the promoters of IRF1, IRF7, and RIG-I, producing their enhanced expression by transcriptional elongation. We also find that BRD4 independently regulates CDK9/phospho-Ser 2 CTD RNA Pol II recruitment to the IRF3-dependent IFN-stimulated genes (ISGs). In vivo, poly(I·C)-induced neutrophilia and mucosal chemokine production are blocked by a small-molecule BRD4 bromodomain inhibitor. Similarly, BRD4 inhibition reduces RSV-induced neutrophilia, mucosal CXC chemokine expression, activation of the IRF7-RIG-I autoamplification loop, mucosal IFN expression, and airway obstruction. RSV infection activates BRD4 acetyltransferase activity on histone H3 Lys (K) 122, demonstrating that RSV infection activates BRD4 in vivo These data validate BRD4 as a major effector of RSV-induced inflammation and disease. BRD4 is required for coupling NF-κB to expression of inflammatory genes and the IRF-RIG-I autoamplification pathway and independently facilitates antiviral ISG expression. BRD4 inhibition may be a strategy to reduce exuberant virus-induced mucosal airway inflammation.IMPORTANCE In the United States, 2.1 million children annually require medical attention for RSV infections. A first line of defense is the expression of the innate gene network by infected epithelial cells. Expression of the innate response requires the recruitment of transcriptional elongation factors to rapidly induce innate response genes through an unknown mechanism. We discovered that RSV infection induces a complex of bromodomain containing 4 (BRD4) with NF-κB and cyclin-dependent kinase 9 (CDK9). BRD4 is required for stable CDK9 binding, phospho-Ser 2 RNA Pol II formation, and histone acetyltransferase activity. Inhibition of BRD4 blocks Toll-like receptor 3 (TLR3)-dependent neutrophilia and RSV-induced inflammation, demonstrating its importance in the mucosal innate response in vivo Our study shows that BRD4 plays a central role in inflammation and activation of the IRF7-RIG-I amplification loop vital for mucosal interferon expression. BRD4 inhibition may be a strategy for modulating exuberant mucosal airway inflammation.

Project description:BackgroundAndrographolide sulfonate (Andro-S), a traditional Chinese medicine, is commonly used to treat pediatric respiratory tract infections in China. However, its therapeutic effects in infections caused by respiratory syncytial virus (RSV) have not been reported. We thus aimed to investigate the therapeutic effects of Andro-S using a mouse model of RSV infection-induced airway inflammation.MethodsImmunocompromised (cyclophosphamide-treated) BALB/c mice were intranasally infected with RSV and treated with intranasal or intraperitoneal Andro-S once daily for five consecutive days, starting on the day of infection. Histopathological changes in the lung were evaluated using hematoxylin and eosin staining. Total inflammatory cell counts and macrophage, lymphocyte, neutrophil, and eosinophil counts in the bronchoalveolar lavage fluid (BALF) were microscopically determined. Interferon-γ (IFN-γ) levels in the BALF were detected using enzyme-linked immunosorbent assay (ELISA). The messenger RNA levels of RSV nucleoprotein (N) and Toll-like receptors (TLRs) 1-9 in lung tissues were determined with quantitative real-time polymerase chain reaction (qRT-PCR). The protein levels of RSV N, RSV fusion protein (F), TLR2, TLR3, and TIR domain-containing adapter-inducing interferon-β (TRIF) were detected via Western blot analysis.ResultsRSV infection caused lung inflammation, manifesting as bronchiolitis, alveolitis, and perivascular inflammation; increased the number of inflammatory cells; and elevated IFN-γ levels in the BALF. Lung inflammation was positively correlated with pulmonary RSV N levels in infected mice. Intranasal Andro-S significantly downregulated RSV N, RSV F, TLR3, and TRIF protein expression in the lung and ameliorated lung inflammation in infected animals. However, intraperitoneal Andro-S showed no effects on lung inflammation caused by RSV infection.ConclusionsIntranasal Andro-S inhibits RSV replication and ameliorates RSV infection-induced lung inflammation by downregulating TLR3 and TRIF. Therefore, intranasal administration may be a suitable drug delivery method for treating RSV infection.

Dataset Information

Central Role of the NF-?B Pathway in the Scgb1a1-Expressing Epithelium in Mediating Respiratory Syncytial Virus-Induced Airway Inflammation.

Publications

Central Role of the NF-κB Pathway in the <i>Scgb1a1</i>-Expressing Epithelium in Mediating Respiratory Syncytial Virus-Induced Airway Inflammation.

Similar Datasets

OmicsDI is part of the ELIXIR infrastructure

Tweets