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Rhinoviruses are among the most common viruses to infect man, causing a range of serious respiratory diseases including exacerbations of asthma and COPD. Type I IFN and IL-15 are thought to be required for antiviral immunity; however, their function during rhinovirus infection in vivo is undefined. In RV-infected human volunteers, IL-15 protein expression in fluid from the nasal mucosa and in bronchial biopsies was increased. In mice, RV induced type I IFN-dependent expressions of IL-15 and IL-15Rα, which in turn were required for NK- and CD8+ T-cell responses. Treatment with IL-15–IL-15Rα complexes (IL-15c) boosted RV-induced expression of IL-15, IL-15Rα, IFN-γ, CXCL9, and CXCL10 followed by recruitment of activated, IFN-γ-expressing NK, CD8+, and CD4+ T cells. Treating infected IFNAR1−/− mice with IL-15c similarly increased IL-15, IL-15Rα, IFN-γ, and CXCL9 (but not CXCL10) expression also followed by NK-, CD8+-, and CD4+-T-cell recruitment and activation. We have demonstrated that type I IFN-induced IFN-γ and cellular immunity to RV was mediated by IL-15 and IL-15Rα. Importantly, we also show that IL-15 could be induced via a type I IFN-independent mechanism by IL-15 complex treatment, which in turn was sufficient to drive IFN-γ expression and lymphocyte responses.

Most asthma exacerbations are triggered by virus infections, the majority being caused by human rhinoviruses (RV). In mouse models, γδT cells have been previously demonstrated to influence allergen-driven airways hyper-reactivity (AHR) and can have antiviral activity, implicating them as prime candidates in the pathogenesis of asthma exacerbations. To explore this, we have used human and mouse models of experimental RV-induced asthma exacerbations to examine γδT-cell responses and determine their role in the immune response and associated airways disease. In humans, airway γδT-cell numbers were increased in asthmatic vs. healthy control subjects during experimental infection. Airway and blood γδT-cell numbers were associated with increased airways obstruction and AHR. Airway γδT-cell number was also positively correlated with bronchoalveolar lavage (BAL) virus load and BAL eosinophils and lymphocytes during RV infection. Consistent with our observations of RV-induced asthma exacerbations in humans, infection of mice with allergic airways inflammation increased lung γδT-cell number and activation. Inhibiting γδT-cell responses using anti-γδTCR (anti-γδT-cell receptor) antibody treatment in the mouse asthma exacerbation model increased AHR and airway T helper type 2 cell recruitment and eosinophilia, providing evidence that γδT cells are negative regulators of airways inflammation and disease in RV-induced asthma exacerbations.

Abstract 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 virus-induced 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 virus-induced COPD exacerbations.

Most asthma exacerbations are triggered by virus infections, the majority being caused by human rhinoviruses (RV). In mouse models, γδT cells have been previously demonstrated to influence allergen-driven airways hyper-reactivity (AHR) and can have antiviral activity, implicating them as prime candidates in the pathogenesis of asthma exacerbations. To explore this, we have used human and mouse models of experimental RV-induced asthma exacerbations to examine γδT-cell responses and determine their role in the immune response and associated airways disease. In humans, airway γδT-cell numbers were increased in asthmatic vs. healthy control subjects during experimental infection. Airway and blood γδT-cell numbers were associated with increased airways obstruction and AHR. Airway γδT-cell number was also positively correlated with bronchoalveolar lavage (BAL) virus load and BAL eosinophils and lymphocytes during RV infection. Consistent with our observations of RV-induced asthma exacerbations in humans, infection of mice with allergic airways inflammation increased lung γδT-cell number and activation. Inhibiting γδT-cell responses using anti-γδTCR (anti-γδT-cell receptor) antibody treatment in the mouse asthma exacerbation model increased AHR and airway T helper type 2 cell recruitment and eosinophilia, providing evidence that γδT cells are negative regulators of airways inflammation and disease in RV-induced asthma exacerbations.

Introduction Pulmonary Hypertension (PH) is defined as raised Pulmonary Arterial Systolic Pressure ≥25mmHg at rest on Right Heart Catheterisation.1 Chronic Thromoboembolic Pulmonary Hypertension (CTEPH) is a recognised complication of pulmonary embolism (PE),with a reported annual cumulative incidence of 3.1%.2 Patients with evidence of PH or Right Ventricular Dysfunction (RVD) during admission should be referred for echocardiography usually 3–6 months after discharge to establish PH resolution.1 Objective To identify patients at risk of CTEPH, evaluate their follow-up plans and establish the proportion with evidence of acute RVD/PH who are investigated for persistent PH. Methods Retrospective analysis of all diagnoses of PE on Computed Tomography Pulmonary Angiography (CTPA) in 2010 in a single Trust. Patients were stratified according to size and location of PE, and any reported radiological evidence of RVD. Echocardiography reports were reviewed for evidence of PH. Results 19.3%(329/1702) of CTPA scans revealed PE: Massive (28.6%); Submassive (28.0%); Peripheral (44.4%). Only 17.6%(58/329) had inpatient echocardiography, with 55.1%(32/58) suggesting PH (PASP≥ 36 mmHg). 78.1%(25/32) of these patients survived to 6 months and follow-up echocardiography was performed within 6 months for 40%(10/25) of this subset. Overall, 80.9% (266/329) of patients with confirmed PE survived past 6 months. Follow-up echocardiogram was performed within 6 months on 20.3% (54/266) of survivors; PH was demonstrated in 18.5%(10/54). RV strain was reported in 15.2% (50/329) of CTPA scans. Follow-up echocardiogram was performed within 6 months on 19.5% (8/41) of those alive at 6 months. 84.2%(154/183)of individuals diagnosed with a massive or submassive PE survived to 6 months. Respiratory or cardiology follow-up was planned for 23% (36/154). Conclusions Our findings suggest follow-up after acute PE is suboptimal, potentially missing early PH due to a low number of early echocardiograms. The relatively high percentage of PH on echocardiography compared to reported rates is likely due to selection bias. The results suggest there may be a missed cohort at risk of developing PH, i.e. those with RV strain on CTPA or high thrombus load, being denied early or more aggressive interventions such as pulmonary endarterectomy. References Galié et al. EurRespirJ 2009; 34:1219–63. Pengo et al. NEJM 2004; 350:2257–64.

The relative roles of the endosomal TLR3/7/8 versus the intracellular RNA helicases RIG-I and MDA5 in viral infection is much debated. We investigated the roles of each pattern recognition receptor in rhinovirus infection using primary bronchial epithelial cells. TLR3 was constitutively expressed; however, RIG-I and MDA5 were inducible by 8-12 h following rhinovirus infection. Bronchial epithelial tissue from normal volunteers challenged with rhinovirus in vivo exhibited low levels of RIG-I and MDA5 that were increased at day 4 post infection. Inhibition of TLR3, RIG-I and MDA5 by siRNA reduced innate cytokine mRNA, and increased rhinovirus replication. Inhibition of TLR3 and TRIF using siRNA reduced rhinovirus induced RNA helicases. Furthermore, IFNAR1 deficient mice exhibited RIG-I and MDA5 induction early during RV1B infection in an interferon independent manner. Hence anti-viral defense within bronchial epithelium requires co-ordinated recognition of rhinovirus infection, initially via TLR3/TRIF and later via inducible RNA helicases.