Rhinoviruses are the major cause of asthma exacerbations, and asthmatics have increased susceptibility to rhinovirus and risk of invasive bacterial infections. Here we show deficient induction of interferon-lambdas by rhinovirus in asthmatic primary bronchial epithelial cells and alveolar macrophages, which was highly correlated with severity of rhinovirus-induced asthma exacerbation and virus load in experimentally infected human volunteers. Induction by lipopolysaccharide in asthmatic macrophages was also deficient and correlated with exacerbation severity. These results identify previously unknown mechanisms of susceptibility to infection in asthma and suggest new approaches to prevention and/or treatment of asthma exacerbations.

Acute exacerbations are the major cause of asthma morbidity, mortality, and health-care costs and are difficult to treat and prevent. The majority of asthma exacerbations are associated with rhinovirus (RV) infection, but evidence supporting a causal relationship is weak and mechanisms are poorly understood. We hypothesized that in asthmatic, but not normal, subjects RV infection would induce clinical, physiologic, and pathologic lower airway responses typical of an asthma exacerbation and that these changes would be related to virus replication and impaired T helper 1 (Th1)/IL-10 or augmented Th2 immune responses. We investigated physiologic, virologic, and immunopathologic responses to experimental RV infection in blood, induced sputum, and bronchial lavage in 10 asthmatic and 15 normal volunteers. RV infection induced significantly greater lower respiratory symptoms and lung function impairment and increases in bronchial hyperreactivity and eosinophilic lower airway inflammation in asthmatic compared with normal subjects. In asthmatic, but not normal, subjects virus load was significantly related to lower respiratory symptoms, bronchial hyperreactivity, and reductions in blood total and CD8 ؉ lymphocytes; lung function impairment was significantly related to neutrophilic and eosinophilic lower airway inflammation. The same virologic and clinical outcomes were strongly related to deficient IFN-␥ and IL-10 responses and to augmented IL-4, IL-5, and IL-13 responses. This study demonstrates increased RV-induced clinical illness severity in asthmatic compared with normal subjects, provides evidence of strong relationships between virus load, lower airway virus-induced inflammation and asthma exacerbation severity, and indicates augmented Th2 or impaired Th1 or IL-10 immunity are likely important mechanisms.exacerbation ͉ respiratory viruses ͉ immunology ͉ human experimental virus infection A cute exacerbations are the major cause of asthma morbidity, mortality (1), and health-care costs (2). Inhaled steroids are associated with reduced risk of exacerbation (3); however, optimal therapy in adults reduces exacerbation frequency by only Ϸ40-50% (4, 5). In school-age children inhaled steroids were ineffective at reducing exacerbation frequency, duration, or severity (6), and in preschool children oral steroids are also reported ineffective (7). Current therapy is therefore of limited efficacy and new more effective therapies are urgently required. To identify targets for development of new treatments, better understanding of mechanisms of virus-induced asthma exacerbations is required.Virus infections are associated with 80-85% of pediatric (8, 9) and Ϸ75% of adult (10, 11) asthma exacerbations, and rhinoviruses (RVs) account for two-thirds of virus detections. Asthmatic individuals are more susceptible to naturally occurring RV infection than normal individuals in that lower respiratory tract symptoms and changes in peak expiratory flow (PEF) are more severe and of longer duration (12). We recently found increased RV...

Rationale: Respiratory virus infections are associated with chronic obstructive pulmonary disease (COPD) exacerbations, but a causative relationship has not been proven. Studies of naturally occurring exacerbations are difficult and the mechanisms linking virus infection to exacerbations are poorly understood. We hypothesized that experimental rhinovirus infection in subjects with COPD would reproduce the features of naturally occurring COPD exacerbations and is a valid model of COPD exacerbations. Objectives: To evaluate experimental rhinovirus infection as a model of COPD exacerbation and to investigate the mechanisms of virusinduced exacerbations. Methods: We used experimental rhinovirus infection in 13 subjects with COPD and 13 nonobstructed control subjects to investigate clinical, physiologic, pathologic, and antiviral responses and relationships between virus load and these outcomes. Measurements and Main Results: Clinical data; inflammatory mediators in blood, sputum, and bronchoalveolar lavage; and viral load in nasal lavage, sputum, and bronchoalveolar lavage were measured at baseline and after infection with rhinovirus 16. After rhinovirus infection subjects with COPD developed lower respiratory symptoms, airflow obstruction, and systemic and airway inflammation that were greater and more prolonged compared with the control group. Neutrophil markers in sputum related to clinical outcomes and virus load correlated with inflammatory markers. Virus load was higher and IFN production by bronchoalveolar lavage cells was impaired in the subjects with COPD. Conclusions: We have developed a new model of COPD exacerbation that strongly supports a causal relationship between rhinovirus infection and COPD exacerbations. Impaired IFN production and neutrophilic inflammation may be important mechanisms in virusinduced COPD exacerbations.

There are increased numbers of activated T lymphocytes in the bronchial mucosa of stable chronic obstructive pulmonary disease (COPD) patients. T helper type 17 (Th17) cells release interleukin (IL)-17 as their effector cytokine under the control of IL-22 and IL-23. Furthermore, Th17 numbers are increased in some chronic inflammatory conditions. To investigate the expression of interleukin (IL)-17A, IL-17F, IL-21, IL-22 and IL-23 and of retinoic orphan receptor RORC2, a marker of Th17 cells, in bronchial biopsies from patients with stable COPD of different severity compared with age-matched control subjects. The expression of IL-17A, IL-17F, IL-21, IL-22, IL-23 and RORC2 was measured in the bronchial mucosa using immunohistochemistry and/or quantitative polymerase chain reaction. The number of IL-22(+) and IL-23(+) immunoreactive cells is increased in the bronchial epithelium of stable COPD compared with control groups. In addition, the number of IL-17A(+) and IL-22(+) immunoreactive cells is increased in the bronchial submucosa of stable COPD compared with control non-smokers. In all smokers, with and without disease, and in patients with COPD alone, the number of IL-22(+) cells correlated significantly with the number of both CD4(+) and CD8(+) cells in the bronchial mucosa. RORC2 mRNA expression in the bronchial mucosa was not significantly different between smokers with normal lung function and COPD. Further, we report that endothelial cells express high levels of IL-17A and IL-22. Increased expression of the Th17-related cytokines IL-17A, IL-22 and IL-23 in COPD patients may reflect their involvement, and that of specific IL-17-producing cells, in driving the chronic inflammation seen in COPD.

Rhinovirus infections are frequently followed by secondary bacterial infections in COPD and cleavage of the antimicrobial peptides SLPI and elafin by virus-induced neutrophil elastase may precipitate these secondary bacterial infections. Therapy targeting neutrophil elastase or enhancing innate immunity may be useful novel therapies for prevention of secondary bacterial infections in virus-induced COPD exacerbations.

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Respiratory virus infections are major triggers of acute exacerbations of asthma in both adults and children, implicated in around 80% of paediatric (1) and 75% of adult (2) asthma attacks. They are therefore major causes of asthma morbidity and mortality (3). Of viruses detected in asthma exacerbations, two thirds are rhinoviruses (1). Influenza viruses are also implicated in asthma exacerbations during annual influenza epidemics (2,4,5).Current therapy of asthma exacerbations is of limited efficacy (6-8), new approaches are therefore required.Background: Respiratory viruses, predominantly rhinoviruses are the major cause of asthma exacerbations. Impaired production of interferon-b in rhinovirus infected bronchial epithelial cells (BECs) and of the newly discovered interferon-ks in both BECs and bronchoalveolar lavage cells, is implicated in asthma exacerbation pathogenesis. Thus replacement of deficient interferon is a candidate new therapy for asthma exacerbations. Rhinoviruses and other respiratory viruses infect both BECs and macrophages, but their relative capacities for a-, b-and k-interferon production are unknown. Methods: To provide guidance regarding which interferon type is the best candidate for development for treatment/prevention of asthma exacerbations we investigated respiratory virus induction of a-, b-and k-interferons in BECs and peripheral blood mononuclear cells (PBMCs) by reverse transferase-polymerase chain reaction and enzyme-linked immunosorbent assay. Results: Rhinovirus infection of BEAS-2B BECs induced interferon-a mRNA expression transiently at 8 h and interferon-b later at 24 h while induction of interferon-k was strongly induced at both time points. At 24 h, interferon-a protein was not detected, interferon-b was weakly induced while interferon-k was strongly induced. Similar patterns of mRNA induction were observed in primary BECs, in response to both rhinovirus and influenza A virus infection, though protein levels were below assay detection limits. In PBMCs interferon-a, interferon-b and interferon-k mRNAs were all strongly induced by rhinovirus at both 8 and 24 h and proteins were induced: interferon-a>-b>-k. Thus respiratory viruses induced expression of a-, b-and k-interferons in BECs and PBMCs. In PBMCs interferon-a>-b>-k while in BECs, interferon-k>-b>-a. Conclusions: We conclude that interferon-ks are likely the principal interferons produced during innate responses to respiratory viruses in BECs and interferonas in PBMCs, while interferon-b is produced by both cell types.

Summary Background Allergen immunotherapy (AIT) is the only causal treatment for respiratory allergy. Long-term real-life effectiveness of AIT remains to be demonstrated beyond the evidence from randomised controlled trials (RCTs). Methods REACT (Real world effectiveness in allergy immunotherapy) is a retrospective cohort study using claims data between 2007 and 2017. Study eligibility was a confirmed diagnosis of allergic rhinitis (AR), with or without asthma, and AIT. To ensure comparable groups, AIT-treated subjects were propensity score matched 1:1 with control subjects, using characteristic and potential confounding variables. Outcomes were analysed as within (pre vs post AIT) and between (AIT vs control) group differences across 9 years of follow-up (ClinicalTrial.gov: NCT04125888). Findings 46,024 AIT-treated subjects were matched with control subjects and 14,614 were included in the pre-existing asthma cohort. AIT-treated subjects were 29·5 (16·3) years and 53% were male. Compared to pre-index year, AIT was consistently associated with greater reductions compared to control subjects in AR and asthma prescriptions, including both asthma controller and reliever prescriptions. Additionally, the AIT group had significantly greater likelihood of stepping down asthma treatment ( P <0·0001). In addition to the reduction in asthma treatment in the AIT group, a greater reduction in severe asthma exacerbations was demonstrated ( P <0·05). Reductions in pneumonia with antibiotic prescriptions, hospitalisations, and duration of inpatients stays were all in favour of AIT. Interpretation The study extends the existing RCT evidence for AIT by demonstrating longer-term and sustained effectiveness of AIT in the real world. Additionally, in patients with concurrent asthma, AIT was associated with reduced likelihood of asthma exacerbations and pneumonia. Funding The study was funded by ALK A/S.