transforming-growth-factor-beta and Respiratory-Syncytial-Virus-Infections

Respiratory syncytial virus (RSV) is the leading cause of bronchiolitis and hospitalization that lead to high morbidity and mortality among young infants. T helper 17 (Th17) cells and regulatory T cells (Tregs) play essential roles in the pathogenesis of autoimmune, cancer, and inflammatory diseases. However, whether changes in T-cell subsets are related to the systemic immune responses in RSV-caused bronchiolitis merit further investigation. Three-week-old Sprague Dawley (SD) rats were randomly divided into the normal control (NC) and RSV bronchiolitis (RSV-B) groups. An RSV-B model was successfully established using nasal drip containing RSV. Furthermore, pathological changes in the lung tissues were observed using hematoxylin and eosin staining. Flow cytometry determined the levels of Th17 and Treg subsets. The related cytokines were measured using enzyme-linked immunosorbent assay (ELISA). The expression levels of related transcription factors, such as RORγt and FOXP3, were examined using real-time quantitative PCR and western blot analysis. The RSV-B group exhibited pulmonary interstitial hyperemia and edema, inflammatory cell infiltration, wide alveolar septa, and bronchial collapse and deformation. The percentage of Th17 cells in RSV-B group was about 2.3 fold higher than that of NC group, and the concentration of IL-17, IL-23 and RORγt was higher than in NC group. In contrast, the percentage of Treg cells in the RSV-B group was approximately 0.7 fold lower than that in the NC group, and the levels of IL-10, TGF-β, and FOXP3 in the RSV-B group were lower than those in the NC group. The above results were statistically significant. The changes of Th17/Treg, and their associated cytokines, specific transcription factors, are present in RSV bronchiolitis model rats, which may play an important role in the pathogenesis of RSV bronchiolitis.

Topics: Animals; Biomarkers; Bronchiolitis; Cytokines; Disease Models, Animal; Gene Expression; Immunophenotyping; Interleukin-10; Interleukin-17; Interleukin-23; Leukocytes, Mononuclear; Lymphocyte Count; Rats; Respiratory Syncytial Virus Infections; Respiratory Syncytial Viruses; T-Lymphocytes, Regulatory; Th17 Cells; Transforming Growth Factor beta

Asthma and chronic obstructive pulmonary disease (COPD) exacerbations are commonly associated with respiratory syncytial virus (RSV), rhinovirus (RV) and influenza A virus (IAV) infection. The ensuing airway inflammation is resistant to the anti-inflammatory actions of glucocorticoids (GCs). Viral infection elicits transforming growth factor-β (TGF-β) activity, a growth factor we have previously shown to impair GC action in human airway epithelial cells through the activation of activin-like kinase 5 (ALK5), the type 1 receptor of TGF-β. In the current study, we examine the contribution of TGF-β activity to the GC-resistance caused by viral infection. We demonstrate that viral infection of human bronchial epithelial cells with RSV, RV or IAV impairs GC anti-inflammatory action. Poly(I:C), a synthetic analog of double-stranded RNA, also impairs GC activity. Both viral infection and poly(I:C) increase TGF-β expression and activity. Importantly, the GC impairment was attenuated by the selective ALK5 (TGFβRI) inhibitor, SB431542 and prevented by the therapeutic agent, tranilast, which reduced TGF-β activity associated with viral infection. This study shows for the first time that viral-induced glucocorticoid-insensitivity is partially mediated by activation of endogenous TGF-β.

Topics: Anti-Inflammatory Agents; Antiviral Agents; Asthma; Benzamides; Cell Line; Dioxoles; Drug Resistance, Viral; Enzyme Activation; Epithelial Cells; Glucocorticoids; Humans; Influenza A virus; Influenza, Human; ortho-Aminobenzoates; Picornaviridae Infections; Poly I-C; Protein Serine-Threonine Kinases; Pulmonary Disease, Chronic Obstructive; Receptor, Transforming Growth Factor-beta Type I; Receptors, Transforming Growth Factor beta; Respiratory Mucosa; Respiratory Syncytial Virus Infections; Respiratory Syncytial Viruses; Rhinovirus; Transforming Growth Factor beta

Human respiratory syncytial virus (RSV) is a lung tropic virus causing severe airway diseases including bronchiolitis and pneumonia among infants, children, and immuno-compromised individuals. RSV triggers transforming growth factor-β (TGF-β) production from lung epithelial cells and TGF-β facilitates RSV infection of these cells. However, it is still unknown whether RSV infected myeloid cells like macrophages produce TGF-β and the role of TGF-β if any during RSV infection of these cells. Our study revealed that RSV infected macrophages produce TGF-β and as a consequence these cells activate TGF-β dependent SMAD-2/3 signaling pathway. Further mechanistic studies illustrated a role of autophagy in triggering TGF-β production from RSV infected macrophages. In an effort to elucidate the role of TGF-β and SMAD-2/3 signaling during RSV infection, we surprisingly unfolded the requirement of TGF-β-SMAD2/3 signaling in conferring optimal innate immune antiviral response during RSV infection of macrophages. Type-I interferon (e.g., interferon-β or IFN-β) is a critical host factor regulating innate immune antiviral response during RSV infection. Our study revealed that loss of TGF-β-SMAD2/3 signaling pathway in RSV infected macrophages led to diminished expression and production of IFN-β. Inhibiting autophagy in RSV infected macrophages also resulted in reduced production of IFN-β. Thus, our studies have unfolded the requirement of autophagy-TGF-β-SMAD2/3 signaling network for optimal innate immune antiviral response during RSV infection of macrophages.

Topics: Animals; Antiviral Agents; Autophagy; Beclin-1; Disease Models, Animal; Immunity, Innate; Interferon Type I; Interferon-beta; Macrophages; Mice; Mice, Inbred C57BL; RAW 264.7 Cells; Respiratory Syncytial Virus Infections; Respiratory Syncytial Virus, Human; Signal Transduction; Smad2 Protein; Smad3 Protein; Transforming Growth Factor beta

Human respiratory syncytial virus (RSV) is a major health challenge in the young and elderly owing to the lack of a safe and effective vaccine and proven antiviral drugs. Understanding the mechanisms by which viral genes and proteins modulate the host response to infection is critical for identifying novel disease intervention strategies. In this study, the RSV non-structural protein NS1 was shown to suppress miR-24 expression during infection. Lack of NS1 was linked to increased expression of miR-24, whilst NS1 overexpression suppressed miR-24 expression. NS1 was found to induce Kruppel-like factor 6 (KLF6), a transcription factor that positively regulates the transforming growth factor (TGF)-b pathway to induce cell cycle arrest. Silencing of KLF6 led to increased miR-24 expression via downregulation of TGF-β. Treatment with exogenous TGF-β suppressed miR-24 expression and induced KLF6. Confocal microscopy showed co-localization of KLF6 and RSV NS1. These findings indicated that RSV NS1 interacts with KLF6 and modulates miR-24 expression and TGF-β, which facilitates RSV replication.

Topics: Host-Pathogen Interactions; Humans; Kruppel-Like Factor 6; Kruppel-Like Transcription Factors; MicroRNAs; Proto-Oncogene Proteins; Respiratory Syncytial Virus Infections; Respiratory Syncytial Virus, Human; Transforming Growth Factor beta; Viral Nonstructural Proteins

To observe the percentages of CD4(+);CD25(+); regulatory T cells (Tregs) and Th17 cells and the levels of IL-10, TGF-β and IL-17 in peripheral blood of infants with respiratory syncytial virus (RSV) bronchiolitis. The relationship between above cells, cytokines and RSV bronchiolitis was determined.. Thirty-three infants with RSV bronchiolitis, twenty-eight infants with non-RSV pneumonia and twenty-six healthy infants were enrolled. The percentages of Tregs and Th17 cells in peripheral blood were detected by flow cytometer (FCM), and the levels of IL-10, TGF-β and IL-17 in plasma were determined by ELISA.. The percentage of Tregs and the levels of IL-10 and TGF-β in infants with RSV bronchiolitis were significantly lower than those in infants with non-RSV pneumonia and healthy infants (P<0.05), while the percentage of Th17 cells and the level of IL-17 in infants with RSV bronchiolitis were significantly higher than those in infants with non-RSV pneumonia and healthy infants (P<0.05).. The imbalance between Tregs and Th17 cells in peripheral blood of infants with RSV bronchiolitis may be one of the pathogenesis of RSV bronchiolitis.

Topics: Bronchiolitis, Viral; Enzyme-Linked Immunosorbent Assay; Female; Flow Cytometry; Humans; Infant; Interleukin-10; Interleukin-17; Interleukin-2 Receptor alpha Subunit; Male; Respiratory Syncytial Virus Infections; Respiratory Syncytial Viruses; T-Lymphocytes, Regulatory; Th17 Cells; Transforming Growth Factor beta

Respiratory syncytial virus (RSV) is the leading cause of lower respiratory tract infection in children worldwide. The understanding of neonatal RSV pathogenesis depends on using an animal model that reproduces neonatal RSV disease. Previous studies from us and others demonstrated that the neonatal lamb model resembles human neonatal RSV infection. Here, we provide an extensive and detailed characterization of the histopathology, viral load, cellular infiltration, and cytokine production in lungs and tracheobronchial lymph nodes of lambs inoculated with human RSV strain A2 over the course of infection. In the lung, RSV titers were low at day 3 postinfection, increased significantly by day 6, and decreased to baseline levels at day 14. Infection in the lung was associated with an accumulation of macrophages, CD4(+) and CD8(+) T cells, and a transcriptional response of genes involved in inflammation, chemotaxis, and interferon response, characterized by increased IFNγ, IL-8, MCP-1, and PD-L1, and decreased IFNβ, IL-10, and TGF-β. Laser capture microdissection studies determined that lung macrophage-enriched populations were the source of MCP-1 but not IL-8. Immunoreactivity to caspase 3 occurred within bronchioles and alveoli of day 6-infected lambs. In lung-draining lymph nodes, RSV induced lymphoid hyperplasia, suggesting an ability of RSV to enhance lymphocytic proliferation and differentiation pathways. This study suggests that, in lambs with moderate clinical disease, RSV enhances the activation of caspase cell death and Th1-skewed inflammatory pathways, and complements previous observations that emphasize the role of inflammation in the pathogenesis of RSV disease.

Topics: Animals; Animals, Newborn; Child; Humans; Infant, Newborn; Infant, Newborn, Diseases; Inflammation; Interleukin-8; Lung; Macrophages; Receptors, CCR2; Respiratory Syncytial Virus Infections; Respiratory Syncytial Viruses; Sheep; Transcription, Genetic; Transforming Growth Factor beta

Respiratory syncytial virus (RSV) is a major cause of morbidity and mortality. Previous studies have suggested that T-cell responses may contribute to RSV immunopathology, which could be driven by dendritic cells (DCs). DCs are productively infected by RSV, and during RSV infections, there is an increase of DCs in the lungs with a decrease in the blood. Pediatric populations are particularly susceptible to severe RSV infections; however, DC responses to RSV from pediatric populations have not been examined. In this study, primary isolated DCs from cord blood and adult peripheral blood were compared after RSV infection. Transcriptional profiling and biological network analysis identified transforming growth factor beta (TGF-β) and associated signaling molecules as differentially regulated in the two age groups. TGF-β1 was decreased in RSV-infected adult-blood DCs but increased in RSV-infected cord blood DCs. Coculture of adult RSV-infected DCs with autologous T cells induced secretion of gamma interferon (IFN-γ), interleukin 12p70 (IL-12p70), IL-2, and tumor necrosis factor alpha (TNF-α). Conversely, coculture of cord RSV-infected DCs and autologous T cells induced secretion of IL-4, IL-6, IL-1β, and IL-17. Addition of purified TGF-β1 to adult DC-T-cell cocultures reduced secretion of IFN-γ, IL-12p70, IL-2, and TNF-α, while addition of a TGF-β chemical inhibitor to cord DC-T-cell cocultures increased secretion of IL-12p70. These data suggest that TGF-β acts as a major regulator of RSV DC-T-cell responses, which could contribute to immunopathology during infancy.

Topics: Adult; Biomarkers, Tumor; Blotting, Western; Carcinoma, Squamous Cell; Cell Differentiation; Child; Dendritic Cells; Fetal Blood; Flow Cytometry; Gene Expression Profiling; Humans; Interferon-gamma; Interleukin-2; Interleukin-4; Interleukin-6; Laryngeal Neoplasms; Oligonucleotide Array Sequence Analysis; Respiratory Syncytial Virus Infections; Respiratory Syncytial Viruses; Reverse Transcriptase Polymerase Chain Reaction; RNA, Messenger; T-Lymphocytes; Transforming Growth Factor beta; Tumor Cells, Cultured; Tumor Necrosis Factor-alpha

The mechanisms underlying exacerbation of asthma induced by respiratory syncytial virus (RSV) infection have been extensively studied in human and animal models. However, most of these studies focused on acute inflammation and little is known of its long-term consequences on remodelling of the airway tissue.. The aim of the study was to use a murine model of prolonged allergen-induced airway inflammation to investigate the effect of RSV infection on allergic airway inflammation and tissue remodelling.. We subjected mice to RSV infection before or during the chronic phase of airway challenges with OVA and compared parameters of airway inflammation and remodelling at the end-point of the prolonged allergen-induced airway inflammation protocol.. RSV infection did not affect the severity of airway inflammation in any of the groups studied. However, RSV infection provoked airway remodelling in non-sensitized, allergen-challenged mice that did not otherwise develop any of the features of allergic airways disease. Increased collagen synthesis in the lung and thickening of the bronchial basal membrane was observed in non-sensitized allergen-challenged mice only after prior RSV infection. In addition, fibroblast growth factor (FGF)-2 but not TGF-beta(1) was increased in this group following RSV infection.. Our data show for the first time that RSV infection can prime the lung of mice that are not previously systemically sensitized, to develop airway remodelling in response to allergen upon sole exposure via the airways. Moreover, our results implicate RSV-induced FGF-2 in the remodelling process in vivo.

Topics: Alum Compounds; Analysis of Variance; Animals; Asthma; Bronchoalveolar Lavage Fluid; Collagen; Cytokines; Extracellular Matrix; Female; Fibroblast Growth Factor 2; Immunohistochemistry; Lung; Mice; Mice, Inbred BALB C; Ovalbumin; Respiratory Syncytial Virus Infections; Respiratory Syncytial Viruses; Statistics, Nonparametric; Transforming Growth Factor beta

Asthma is characterized as a chronic inflammatory disease associated with significant tissue remodeling. Patients with asthma are more susceptible to virus-induced exacerbation, which subsequently can lead to increased rates of hospitalization and mortality. While the most common cause of asthma-related deaths is respiratory viral infections, the underlying factors in the lung environment which render asthmatic subjects more susceptible to viral exacerbation are not yet identified. Since transforming growth factor beta (TGF-beta) is a critical cytokine for lung tissue remodeling and asthma phenotype, we have focused on the effects of TGF-beta on viral replication and virus-induced inflammation. Treatment of human epithelial cells with TGF-beta increased respiratory syncytial virus (RSV) replication by approximately fourfold. Tumor necrosis factor alpha (TNF-alpha) mRNA and protein expression were also significantly increased above levels with RSV infection alone. The increase in RSV replication and TNF-alpha expression after TGF-beta treatment was concomitant with an increase in virus-induced p38 mitogen-activated protein kinase activation. Our data reveal a novel effect for TGF-beta on RSV replication and provide a potential mechanism for the exaggerated inflammatory response observed in asthmatic subjects during respiratory viral infections.

Topics: Cell Line; Cell Line, Tumor; Epithelial Cells; Humans; Recombinant Proteins; Respiratory Syncytial Virus Infections; Respiratory Syncytial Virus, Human; RNA, Messenger; Transforming Growth Factor beta; Tumor Necrosis Factor-alpha; Virus Replication

Respiratory infections are the third leading cause of death worldwide. Complications arise directly as a consequence of pathogen replication or indirectly due to aberrant or excessive immune responses. In the following report, we evaluate the efficacy, in a murine model, of nasally delivered DNA encoding TGF-beta1 to suppress immunopathology in response to a variety of infectious agents. A single nasal administration suppressed lymphocyte responses to Cryptococcus neoformans, influenza virus and respiratory syncytial virus. The suppression did not depend on the phenotype of the responding T cell, since both Th1 and Th2 responses were affected. During Th2-inducing infection, pulmonary eosinophilic responses were significantly suppressed. In all cases, however, suppressed immunity correlated with increased susceptibility to infection. We conclude that nasal TGF-beta treatment could be used to prevent pulmonary, pathogen-driven eosinophilic disease, although anti-pathogen strategies will need to be administered concordantly.

Topics: Animals; Cryptococcosis; Female; Gene Expression; Inflammation; Mice; Mice, Inbred BALB C; Mice, Inbred C57BL; Orthomyxoviridae Infections; Plasmids; Pulmonary Eosinophilia; Respiratory Syncytial Virus Infections; T-Lymphocytes, Helper-Inducer; Transforming Growth Factor beta