Effect of CRTH2 antagonism on the response to experimental rhinovirus infection in asthma: a pilot randomised controlled trial.

BACKGROUND AND AIMS: The chemoattractant receptor-homologous molecule expressed on T helper type 2 cells (CRTH2) antagonist timapiprant improved lung function and asthma control in a phase 2 study, with evidence suggesting reduced exacerbations. We aimed to assess whether timapiprant attenuated or prevented asthma exacerbations induced by experimental rhinovirus (RV) infection. We furthermore hypothesised that timapiprant would dampen RV-induced type 2 inflammation and consequently improve antiviral immune responses. METHODS: Atopic patients with partially controlled asthma on maintenance inhaled corticosteroids were randomised to timapiprant (n=22) or placebo (n=22) and challenged with RV-A16 3 weeks later. The primary endpoint was the cumulative lower respiratory symptom score over the 14 days post infection. Upper respiratory symptoms, spirometry, airway hyperresponsiveness, exhaled nitric oxide, RV-A16 virus load and soluble mediators in upper and lower airways samples, and CRTH2 staining in bronchial biopsies were additionally assessed before and during RV-A16 infection. RESULTS: Six subjects discontinued the study and eight were not infected; outcomes were assessed in 16 timapiprant-treated and 14 placebo-treated, successfully infected subjects. There were no differences between treatment groups in clinical exacerbation severity including cumulative lower respiratory symptom score day 0-14 (difference 3.0 (95% CI -29.0 to 17.0), p=0.78), virus load, antiviral immune responses, or RV-A16-induced airway inflammation other than in the bronchial biopsies, where CRTH2 staining was increased during RV-A16 infection in the placebo-treated but not the timapiprant-treated group. Timapiprant had a favourable safety profile, with no deaths, serious adverse events or drug-related withdrawals. CONCLUSION: Timapiprant treatment had little impact on the clinicopathological changes induced by RV-A16 infection in partially controlled asthma.

Experimental rhinovirus infection induces an antiviral response in circulating B cells which is dysregulated in patients with asthma.

BACKGROUND: Rhinoviruses are the predominant cause of respiratory viral infections and are strongly associated with asthma exacerbations. While humoral immunity plays an important role during virus infections, cellular aspects of this response are less well understood. Here, we investigated the antiviral response of circulating B cells upon experimental rhinovirus infection in healthy individuals and asthma patients. METHODS: We purified B cells from experimentally infected healthy individuals and patients with asthma and subjected them to total RNA-sequencing. Rhinovirus-derived RNA was measured in isolated B cells using a highly sensitive PCR. B cells were stimulated with rhinovirus in vitro to further study gene expression, expression of antiviral proteins and B-cell differentiation in response rhinovirus stimulation. Protein expression of pro-inflammatory cytokines in response to rhinovirus was assessed using a proximity extension assay. RESULTS: B cells isolated from experimentally infected subjects exhibited an antiviral gene profile linked to IFN-alpha, carried viral RNA in vivo and were transiently infected by rhinovirus in vitro. B cells rapidly differentiated into plasmablasts upon rhinovirus stimulation. While B cells lacked expression of interferons in response to rhinovirus exposure, co-stimulation with rhinovirus and IFN-alpha upregulated pro-inflammatory cytokine expression suggesting a potential new function of B cells during virus infections. Asthma patients showed extensive upregulation and dysregulation of antiviral gene expression. CONCLUSION: These findings add to the understanding of systemic effects of rhinovirus infections on B-cell responses in the periphery, show potential dysregulation in patients with asthma and might also have implications during infection with other respiratory viruses.

Innate-like Gene Expression of Lung-Resident Memory CD8+ T Cells during Experimental Human Influenza: A Clinical Study.

Rationale: Suboptimal vaccine immunogenicity and antigenic mismatch, compounded by poor uptake, means that influenza remains a major global disease. T cells recognizing peptides derived from conserved viral proteins could enhance vaccine-induced cross-strain protection. Objectives: To investigate the kinetics, phenotypes, and function of influenza virus-specific CD8+ resident memory T (Trm) cells in the lower airway and infer the molecular pathways associated with their response to infection in vivo. Methods: Healthy volunteers, aged 18-55, were inoculated intranasally with influenza A/California/4/09(H1N1). Blood, upper airway, and (in a subgroup) lower airway samples were obtained throughout infection. Symptoms were assessed by using self-reported diaries, and the nasal viral load was assessed by using quantitative PCR. T-cell responses were analyzed by using a three-color FluoroSpot assay, flow cytometry with MHC I-peptide tetramers, and RNA sequencing, with candidate markers being confirmed by using the immunohistochemistry results for endobronchial biopsy specimens. Measurements and Main Results: After challenge, 57% of participants became infected. Preexisting influenza-specific CD8+ T cells in blood correlated strongly with a reduced viral load, which peaked at Day 3. Influenza-specific CD8+ T cells in BAL fluid were highly enriched and predominantly expressed the Trm markers CD69 and CD103. Comparison between preinfection CD8+ T cells in BAL fluid and blood by using RNA sequencing revealed 3,928 differentially expressed genes, including all major Trm-cell markers. However, gene set enrichment analysis of BAL-fluid CD8+ T cells showed primarily innate cell-related pathways and, during infection, included upregulation of innate chemokines (Cxcl1, Cxcl10, and Cxcl16) that were also expressed by CD8+ cells in bronchial tissues. Conclusions: CD8+ Trm cells in the human lung display innate-like gene and protein expression that demonstrates blurred divisions between innate and adaptive immunity. Clinical study registered with www.clinicaltrials.gov (NCT02755948).

Inhaled corticosteroids downregulate the SARS-CoV-2 receptor ACE2 in COPD through suppression of type I interferon.

BACKGROUND: The mechanisms underlying altered susceptibility and propensity to severe Coronavirus disease 2019 (COVID-19) disease in at-risk groups such as patients with chronic obstructive pulmonary disease (COPD) are poorly understood. Inhaled corticosteroids (ICSs) are widely used in COPD, but the extent to which these therapies protect or expose patients to risk of severe COVID-19 is unknown. OBJECTIVE: The aim of this study was to evaluate the effect of ICSs following pulmonary expression of the SARS-CoV-2 viral entry receptor angiotensin-converting enzyme-2 (ACE2). METHODS: We evaluated the effect of ICS administration on pulmonary ACE2 expression in vitro in human airway epithelial cell cultures and in vivo in mouse models of ICS administration. Mice deficient in the type I IFN-α/ß receptor (Ifnar1-/-) and administration of exogenous IFN-ß were used to study the functional role of type-I interferon signaling in ACE2 expression. We compared sputum ACE2 expression in patients with COPD stratified according to use or nonuse of ICS. RESULTS: ICS administration attenuated ACE2 expression in mice, an effect that was reversed by exogenous IFN-ß administration, and Ifnar1-/- mice had reduced ACE2 expression, indicating that type I interferon contributes mechanistically to this effect. ICS administration attenuated expression of ACE2 in airway epithelial cell cultures from patients with COPD and in mice with elastase-induced COPD-like changes. Compared with ICS nonusers, patients with COPD who were taking ICSs also had reduced sputum expression of ACE2. CONCLUSION: ICS therapies in COPD reduce expression of the SARS-CoV-2 entry receptor ACE2. This effect may thus contribute to altered susceptibility to COVID-19 in patients with COPD.

Loss of regulatory capacity in Treg cells following rhinovirus infection.

BACKGROUND: Respiratory infections with rhinoviruses (RV) are strongly associated with development and exacerbations of asthma, and they pose an additional health risk for subjects with allergy. OBJECTIVE: How RV infections and chronic allergic diseases are linked and what role RV plays in the breaking of tolerance in regulatory T (Treg) cells is unknown. Therefore, this study aims to investigate the effects of RV on Treg cells. METHODS: Treg cells were isolated from subjects with asthma and controls after experimental infection with the RV-A16 (RV16) and analyzed with next-generation sequencing. Additionally, suppression assays, quantitative PCR assays, and protein quantifications were performed with Treg cells after in vitro RV16 infection. RESULTS: RV16 induced a strong antiviral response in Treg cells from subjects with asthma and controls, including the upregulation of IFI44L, MX1, ISG15, IRF7, and STAT1. In subjects with asthma, the inflammatory response was exaggerated and showed a dysregulated immune response compared with that in the controls. Furthermore, subjects with asthma failed to upregulate several immunosuppressive molecules such as CTLA4 and CD69, and they upregulated the inflammasome-related genes PYCARD and AIM2. Additionally, RV16 reduced the suppressive capacity of Treg cells from healthy subjects and subjects with asthma in vitro and increased TH2 cell-type cytokine production. CONCLUSIONS: Treg cells from healthy subjects and subjects with asthma displayed an antiviral response after RV infection and showed reduced suppressive capacity. These data suggest that Treg cell function might be altered or impaired during RV infections, which might play an important role in the association between RV and the development of asthma and asthma exacerbations.

Targeted Retreatment of Incompletely Recovered Chronic Obstructive Pulmonary Disease Exacerbations with Ciprofloxacin. A Double-Blind, Randomized, Placebo-controlled, Multicenter, Phase III Clinical Trial.

Rationale: Chronic obstructive pulmonary disease (COPD) exacerbations are prone to nonrecovery, but there are no data about the effectiveness of retreatment for these prolonged events. We examined whether further therapy with ciprofloxacin for incompletely resolved COPD exacerbations prolonged the time until the next event.Objectives: To assess whether incompletely recovered COPD exacerbations benefit from additional treatment with ciprofloxacin, at Day 14.Methods: In a multicenter, randomized double-blind placebo-controlled trial, we studied retreatment with oral ciprofloxacin 500 mg or matched placebo twice daily for 7 days in patients with Global Initiative for Chronic Obstructive Lung Disease stage II-IV COPD and persistent symptoms and/or serum C-reactive protein ≥8 mg/L initiated 14 (±3) days after an index COPD exacerbation. The primary outcome was the time to the next exacerbation within a 90-day period.Measurements and Main Results: Among 826 patients screened at four centers, 144 eligible participants with incomplete recovery were randomized to receive ciprofloxacin (n = 72) or placebo (n = 72). Within 90 days of randomization, 57% of the patients in the ciprofloxacin group and 53% in the placebo group experienced one or more exacerbations. The median time to the next exacerbation was 32.5 days (interquartile range 13-50) in the placebo arm and 34 days (interquartile range 17-62) in the ciprofloxacin arm, which was not significantly different (adjusted hazard ratio, 1.07; 95% confidence interval, 0.68-1.68; P = 0.76). No significant differences were seen in quality-of-life scores or lung function between the treatment groups.Conclusions: In patients with persistent symptoms and/or raised C-reactive protein 14 days after a COPD exacerbation, an additional course of ciprofloxacin resulted in no additional benefit compared with placebo. This suggests that nonrecovered exacerbations are not driven by ongoing bacterial infection and may potentially be targeted with antiinflammatory therapy.Clinical trial registered with www.clinicaltrials.gov (NCT02300220).

Bronchial mucosal inflammation and illness severity in response to experimental rhinovirus infection in COPD.

BACKGROUND: Respiratory viral infection causes chronic obstructive pulmonary disease (COPD) exacerbations. We previously reported increased bronchial mucosa eosinophil and neutrophil inflammation in patients with COPD experiencing naturally occurring exacerbations. But it is unclear whether virus per se induces bronchial mucosal inflammation, nor whether this relates to exacerbation severity. OBJECTIVES: We sought to determine the extent and nature of bronchial mucosal inflammation following experimental rhinovirus (RV)-16-induced COPD exacerbations and its relationship to disease severity. METHODS: Bronchial mucosal inflammatory cell phenotypes were determined at preinfection baseline and following experimental RV infection in 17 Global Initiative for Chronic Obstructive Lung Disease stage II subjects with COPD and as controls 20 smokers and 11 nonsmokers with normal lung function. No subject had a history of asthma/allergic rhinitis: all had negative results for aeroallergen skin prick tests. RESULTS: RV infection increased the numbers of bronchial mucosal eosinophils and neutrophils only in COPD and CD8+ T lymphocytes in patients with COPD and nonsmokers. Monocytes/macrophages, CD4+ T lymphocytes, and CD20+ B lymphocytes were increased in all subjects. At baseline, compared with nonsmokers, subjects with COPD and smokers had increased numbers of bronchial mucosal monocytes/macrophages and CD8+ T lymphocytes but fewer numbers of CD4+ T lymphocytes and CD20+ B lymphocytes. The virus-induced inflammatory cells in patients with COPD were positively associated with virus load, illness severity, and reductions in lung function. CONCLUSIONS: Experimental RV infection induces bronchial mucosal eosinophilia and neutrophilia only in patients with COPD and monocytes/macrophages and lymphocytes in both patients with COPD and control subjects. The virus-induced inflammatory cell phenotypes observed in COPD positively related to virus load and illness severity. Antiviral/anti-inflammatory therapies could attenuate bronchial inflammation and ameliorate virus-induced COPD exacerbations.

Human Rhinovirus Impairs the Innate Immune Response to Bacteria in Alveolar Macrophages in Chronic Obstructive Pulmonary Disease.

Rationale: Human rhinovirus (HRV) is a common cause of chronic obstructive pulmonary disease (COPD) exacerbations. Secondary bacterial infection is associated with more severe symptoms and delayed recovery. Alveolar macrophages clear bacteria from the lung and maintain lung homeostasis through cytokine secretion. These processes are defective in COPD. The effect of HRV on macrophage function is unknown. Objectives: To investigate the effect of HRV on phagocytosis and cytokine response to bacteria by alveolar macrophages and monocyte-derived macrophages (MDM) in COPD and healthy control subjects. Methods: Alveolar macrophages were obtained by bronchoscopy and MDM by adherence. Macrophages were exposed to HRV16 (multiplicity of infection 5), polyinosinic:polycytidylic acid (poly I:C) 30 µg/ml, IFN-ß 10 µg/ml, IFN-γ 10 µg/ml, or medium control for 24 hours. Phagocytosis of fluorescently labeled Haemophilus influenzae or Streptococcus pneumoniae was assessed by fluorimetry. CXCL8 (IL-8), IL-6, TNF-α (tumor necrosis factor-α), and IL-10 release was measured by ELISA. Measurements and Main Results: HRV significantly impaired phagocytosis of H. influenzae by 23% in MDM (n = 37; P = 0.004) and 18% in alveolar macrophages (n = 20; P < 0.0001) in COPD. HRV also significantly reduced phagocytosis of S. pneumoniae by 33% in COPD MDM (n = 20; P = 0.0192). There was no effect in healthy control subjects. Phagocytosis of H. influenzae was also impaired by poly I:C but not IFN-ß or IFN-γ in COPD MDM. HRV significantly reduced cytokine responses to H. influenzae. The IL-10 response to H. influenzae was significantly impaired by poly I:C, IFN-ß, and IFN-γ in COPD cells. Conclusions: HRV impairs phagocytosis of bacteria in COPD, which may lead to an outgrowth of bacteria. HRV also impairs cytokine responses to bacteria via the TLR3/IFN pathway, which may prevent resolution of inflammation leading to prolonged exacerbations in COPD.

Bronchial mucosal IFN-α/ß and pattern recognition receptor expression in patients with experimental rhinovirus-induced asthma exacerbations.

BACKGROUND: The innate immune system senses viral infection through pattern recognition receptors (PRRs), leading to type I interferon production. The role of type I interferon and PPRs in rhinovirus-induced asthma exacerbations in vivo are uncertain. OBJECTIVES: We sought to compare bronchial mucosal type I interferon and PRR expression at baseline and after rhinovirus infection in atopic asthmatic patients and control subjects. METHODS: Immunohistochemistry was used to detect expression of IFN-α, IFN-ß, and the PRRs: Toll-like receptor 3, melanoma differentiation-associated gene 5, and retinoic acid-inducible protein I in bronchial biopsy specimens from 10 atopic asthmatic patients and 15 nonasthmatic nonatopic control subjects at baseline and on day 4 and 6 weeks after rhinovirus infection. RESULTS: We observed IFN-α/ß deficiency in the bronchial epithelium at 3 time points in asthmatic patients in vivo. Lower epithelial IFN-α/ß expression was related to greater viral load, worse airway symptoms, airway hyperresponsiveness, and reductions in lung function during rhinovirus infection. We found lower frequencies of bronchial subepithelial monocytes/macrophages expressing IFN-α/ß in asthmatic patients during infection. Interferon deficiency at baseline was not accompanied by deficient PRR expression in asthmatic patients. Both epithelial and subepithelial PRR expression were induced during rhinovirus infection. Rhinovirus infection-increased numbers of subepithelial interferon/PRR-expressing inflammatory cells were related to greater viral load, airway hyperresponsiveness, and reductions in lung function. CONCLUSIONS: Bronchial epithelial IFN-α/ß expression and numbers of subepithelial IFN-α/ß-expressing monocytes/macrophages during infection were both deficient in asthmatic patients. Lower epithelial IFN-α/ß expression was associated with adverse clinical outcomes after rhinovirus infection in vivo. Increases in numbers of subepithelial cells expressing interferon/PRRs during infection were also related to greater viral load/illness severity.

Antiviral immunity is impaired in COPD patients with frequent exacerbations.

Patients with frequent exacerbations represent a chronic obstructive pulmonary disease (COPD) subgroup requiring better treatment options. The aim of this study was to determine the innate immune mechanisms that underlie susceptibility to frequent exacerbations in COPD. We measured sputum expression of immune mediators and bacterial loads in samples from patients with COPD at stable state and during virus-associated exacerbations. In vitro immune responses to rhinovirus infection in differentiated primary bronchial epithelial cells (BECs) sampled from patients with COPD were additionally evaluated. Patients were stratified as frequent exacerbators (≥2 exacerbations in the preceding year) or infrequent exacerbators (<2 exacerbations in the preceding year) with comparisons made between these groups. Frequent exacerbators had reduced sputum cell mRNA expression of the antiviral immune mediators type I and III interferons and reduced interferon-stimulated gene (ISG) expression when clinically stable and during virus-associated exacerbation. A role for epithelial cell-intrinsic innate immune dysregulation was identified: induction of interferons and ISGs during in vitro rhinovirus (RV) infection was also impaired in differentiated BECs from frequent exacerbators. Frequent exacerbators additionally had increased sputum bacterial loads at 2 wk following virus-associated exacerbation onset. These data implicate deficient airway innate immunity involving epithelial cells in the increased propensity to exacerbations observed in some patients with COPD. Therapeutic approaches to boost innate antimicrobial immunity in the lung could be a viable strategy for prevention and treatment of frequent exacerbations.

Role of airway glucose in bacterial infections in patients with chronic obstructive pulmonary disease.

BACKGROUND: Patients with chronic obstructive pulmonary disease (COPD) have increased susceptibility to respiratory tract infection, which contributes to disease progression and mortality, but mechanisms of increased susceptibility to infection remain unclear. OBJECTIVES: The aim of this study was to determine whether glucose concentrations were increased in airway samples (nasal lavage fluid, sputum, and bronchoalveolar lavage fluid) from patients with stable COPD and to determine the effects of viral infection on sputum glucose concentrations and how airway glucose concentrations relate to bacterial infection. METHODS: We measured glucose concentrations in airway samples collected from patients with stable COPD and smokers and nonsmokers with normal lung function. Glucose concentrations were measured in patients with experimentally induced COPD exacerbations, and these results were validated in patients with naturally acquired COPD exacerbations. Relationships between sputum glucose concentrations, inflammatory markers, and bacterial load were examined. RESULTS: Sputum glucose concentrations were significantly higher in patients with stable COPD compared with those in control subjects without COPD. In both experimental virus-induced and naturally acquired COPD exacerbations, sputum and nasal lavage fluid glucose concentrations were increased over baseline values. There were significant correlations between sputum glucose concentrations and sputum inflammatory markers, viral load, and bacterial load. Airway samples with higher glucose concentrations supported more Pseudomonas aeruginosa growth in vitro. CONCLUSIONS: Airway glucose concentrations are increased in patients with stable COPD and further increased during COPD exacerbations. Increased airway glucose concentrations might contribute to bacterial infections in both patients with stable and those with exacerbated COPD. This has important implications for the development of nonantibiotic therapeutic strategies for the prevention or treatment of bacterial infection in patients with COPD.

Interleukin-18 is associated with protection against rhinovirus-induced colds and asthma exacerbations.

Rhinoviruses cause the common cold and exacerbations of asthma. Animal models of infection have identified a protective role for interleukin-18 (IL-18). Following experimental rhinovirus infection, we observed increased respiratory symptoms in healthy and asthmatic subjects with low nasal and bronchial IL-18 levels.

The role of bacteria in the pathogenesis and progression of idiopathic pulmonary fibrosis.

RATIONALE: Idiopathic pulmonary fibrosis (IPF) is a progressive lung disease of unknown cause that leads to respiratory failure and death within 5 years of diagnosis. Overt respiratory infection and immunosuppression carry a high morbidity and mortality, and polymorphisms in genes related to epithelial integrity and host defense predispose to IPF. OBJECTIVES: To investigate the role of bacteria in the pathogenesis and progression of IPF. METHODS: We prospectively enrolled patients diagnosed with IPF according to international criteria together with healthy smokers, nonsmokers, and subjects with moderate chronic obstructive pulmonary disease as control subjects. Subjects underwent bronchoalveolar lavage (BAL), from which genomic DNA was isolated. The V3-V5 region of the bacterial 16S rRNA gene was amplified, allowing quantification of bacterial load and identification of communities by 16S rRNA quantitative polymerase chain reaction and pyrosequencing. MEASUREMENTS AND MAIN RESULTS: Sixty-five patients with IPF had double the burden of bacteria in BAL fluid compared with 44 control subjects. Baseline bacterial burden predicted the rate of decline in lung volume and risk of death and associated independently with the rs35705950 polymorphism of the MUC5B mucin gene, a proven host susceptibility factor for IPF. Sequencing yielded 912,883 high-quality reads from all subjects. We identified Haemophilus, Streptococcus, Neisseria, and Veillonella spp. to be more abundant in cases than control subjects. Regression analyses indicated that these specific operational taxonomic units as well as bacterial burden associated independently with IPF. CONCLUSIONS: IPF is characterized by an increased bacterial burden in BAL that predicts decline in lung function and death. Trials of antimicrobial therapy are needed to determine if microbial burden is pathogenic in the disease.

IL-33-dependent type 2 inflammation during rhinovirus-induced asthma exacerbations in vivo.

RATIONALE: Rhinoviruses are the major cause of asthma exacerbations; however, its underlying mechanisms are poorly understood. We hypothesized that the epithelial cell-derived cytokine IL-33 plays a central role in exacerbation pathogenesis through augmentation of type 2 inflammation. OBJECTIVES: To assess whether rhinovirus induces a type 2 inflammatory response in asthma in vivo and to define a role for IL-33 in this pathway. METHODS: We used a human experimental model of rhinovirus infection and novel airway sampling techniques to measure IL-4, IL-5, IL-13, and IL-33 levels in the asthmatic and healthy airways during a rhinovirus infection. Additionally, we cultured human T cells and type 2 innate lymphoid cells (ILC2s) with the supernatants of rhinovirus-infected bronchial epithelial cells (BECs) to assess type 2 cytokine production in the presence or absence of IL-33 receptor blockade. MEASUREMENTS AND MAIN RESULTS: IL-4, IL-5, IL-13, and IL-33 are all induced by rhinovirus in the asthmatic airway in vivo and relate to exacerbation severity. Further, induction of IL-33 correlates with viral load and IL-5 and IL-13 levels. Rhinovirus infection of human primary BECs induced IL-33, and culture of human T cells and ILC2s with supernatants of rhinovirus-infected BECs strongly induced type 2 cytokines. This induction was entirely dependent on IL-33. CONCLUSIONS: IL-33 and type 2 cytokines are induced during a rhinovirus-induced asthma exacerbation in vivo. Virus-induced IL-33 and IL-33-responsive T cells and ILC2s are key mechanistic links between viral infection and exacerbation of asthma. IL-33 inhibition is a novel therapeutic approach for asthma exacerbations.

Tolerogenic signaling by pulmonary CD1c+ dendritic cells induces regulatory T cells in patients with chronic obstructive pulmonary disease by IL-27/IL-10/inducible costimulator ligand.

BACKGROUND: Increased mortality rates in patients with chronic obstructive pulmonary disease (COPD) are largely due to severe infectious exacerbations. Impaired respiratory immunity is linked to the enhanced susceptibility to infections. Dendritic cells (DCs) direct host immune responses toward immunity or tolerance. Pulmonary CD1c(+) DCs elicit robust antiviral immune responses in healthy subjects. Nevertheless, their functional specialization in patients with COPD remains unexplored. OBJECTIVE: We sought to better understand the mechanisms that suppress respiratory immunity in patients with COPD by examining the immunostimulatory and tolerogenic properties of pulmonary CD1c(+) DCs. METHODS: We analyzed the expression of costimulatory and tolerogenic molecules by pulmonary CD1c(+) DCs from patients with COPD (CD1c(+)DCCOPD) and former smokers without COPD. We isolated lung CD1c(+) DCs and determined their ability to stimulate allogeneic T-cell responses. The suppressive effects of lung CD1c(+) DCs and CD1c(+) DC-primed T cells on mixed leukocyte reactions were examined. An experimental human model of COPD exacerbation was used to investigate the levels of critical immunosuppressive molecules in vivo. RESULTS: CD1c(+) DCs from patients with COPD hinder T-cell effector functions and favor the generation of suppressive IL-10-secreting CD4(+) T cells that function through IL-10 and TGF-ß. IL-27, IL-10, and inducible T-cell costimulator ligand signaling are essential for CD1c(+)DCCOPD-mediated differentiation of IL-10-producing suppressive T cells. Exposure of lung CD1c(+) DCs from nonobstructed subjects to lungs of patients with COPD confers tolerogenic properties. IL-27 and IL-10 levels are increased in the lung microenvironment on rhinovirus-induced COPD exacerbation in vivo. CONCLUSION: We identify a novel tolerogenic circuit encompassing suppressive CD1c(+) DCs and regulatory T cells in patients with COPD that might be implicated in impaired respiratory immunity and further highlight IL-10 and IL-27 as potent therapeutic targets.

Outgrowth of the bacterial airway microbiome after rhinovirus exacerbation of chronic obstructive pulmonary disease.

RATIONALE: Rhinovirus infection is followed by significantly increased frequencies of positive, potentially pathogenic sputum cultures in chronic obstructive pulmonary disease (COPD). However, it remains unclear whether these represent de novo infections or an increased load of organisms from the complex microbial communities (microbiome) in the lower airways. OBJECTIVES: To investigate the effect of rhinovirus infection on the airway bacterial microbiome. METHODS: Subjects with COPD (n = 14) and healthy control subjects with normal lung function (n = 17) were infected with rhinovirus. Induced sputum was collected at baseline before rhinovirus inoculation and again on Days 5, 15, and 42 after rhinovirus infection and DNA was extracted. The V3-V5 region of the bacterial 16S ribosomal RNA gene was amplified and pyrosequenced, resulting in 370,849 high-quality reads from 112 of the possible 124 time points. MEASUREMENTS AND MAIN RESULTS: At 15 days after rhinovirus infection, there was a sixfold increase in 16S copy number (P = 0.007) and a 16% rise in numbers of proteobacterial sequences, most notably in potentially pathogenic Haemophilus influenzae (P = 2.7 × 10(-20)), from a preexisting community. These changes occurred only in the sputum microbiome of subjects with COPD and were still evident 42 days after infection. This was in contrast to the temporal stability demonstrated in the microbiome of healthy smokers and nonsmokers. CONCLUSIONS: After rhinovirus infection, there is a rise in bacterial burden and a significant outgrowth of Haemophilus influenzae from the existing microbiota of subjects with COPD. This is not observed in healthy individuals. Our findings suggest that rhinovirus infection in COPD alters the respiratory microbiome and may precipitate secondary bacterial infections.