Eosinophilic airway diseases: basic science, clinical manifestations and future challenges.

Eosinophils have a broad range of functions, both homeostatic and pathological, mediated through an array of cell surface receptors and specific secretory granules that promote interactions with their microenvironment. Eosinophil development, differentiation, activation, survival and recruitment are closely regulated by a number of type 2 cytokines, including interleukin (IL)-5, the key driver of eosinophilopoiesis. Evidence shows that type 2 inflammation, driven mainly by interleukin (IL)-4, IL-5 and IL-13, plays an important role in the pathophysiology of eosinophilic airway diseases, including asthma, chronic rhinosinusitis with nasal polyps, eosinophilic granulomatosis with polyangiitis and hypereosinophilic syndrome. Several biologic therapies have been developed to suppress type 2 inflammation, namely mepolizumab, reslizumab, benralizumab, dupilumab, omalizumab and tezepelumab. While these therapies have been associated with clinical benefits in a range of eosinophilic diseases, their development has highlighted several challenges and directions for future research. These include the need for further information on disease progression and identification of treatable traits, including clinical characteristics or biomarkers that will improve the prediction of treatment response. The Nordic countries have a long tradition of collaboration using patient registries and Nordic asthma registries provide unique opportunities to address these research questions. One example of such a registry is the NORdic Dataset for aSThmA Research (NORDSTAR), a longitudinal population-based dataset containing all 3.3 million individuals with asthma from four Nordic countries (Denmark, Finland, Norway and Sweden). Large-scale, real-world registry data such as those from Nordic countries may provide important information regarding the progression of eosinophilic asthma, in addition to clinical characteristics or biomarkers that could allow targeted treatment and ensure optimal patient outcomes.

Effects of switching from a metered dose inhaler to a dry powder inhaler on climate emissions and asthma control: post-hoc analysis.

OBJECTIVE: To compare the effects of switching from a pressurised metered dose inhaler (pMDI)-based to a dry powder inhaler (DPI)-based maintenance therapy versus continued usual care on greenhouse gas emissions (carbon dioxide equivalents, CO2e) and asthma control. METHODS: This post-hoc analysis was based on a subset of 2236 (53%) patients from the Salford Lung Study in Asthma who at baseline were using a pMDI-based controller therapy. During the study patients were randomised to fluticasone furoate/vilanterol (FF/VI) via the ELLIPTA DPI (switched from pMDI to DPI) (n=1081) or continued their usual care treatment (n=1155), and were managed in conditions close to everyday clinical practice. Annual CO2e (kg) was calculated for the total number of maintenance and rescue inhalers prescribed. Asthma control was assessed by the proportion of ACT responders (composite of ACT total score ≥20 and/or increase from baseline ≥3). RESULTS: The groups were well matched for demographic characteristics and baseline Asthma Control Test (ACT) total score (mean age: 49 years; mean ACT score: usual care, 16.6; FF/VI, 16.5). Annual CO2e kg per patient (maintenance plus rescue therapy) was significantly lower with FF/VI DPI treatment ('switch' group) than usual care (least squares geometric mean 108 kg (95% CI 102 to 114) vs 240 kg (95% CI 229 to 252), p<0.001). Asthma control was consistently superior over the 12 months in the FF/VI DPI group compared with usual care. CONCLUSIONS: Patients switching from a pMDI-based to a DPI-based maintenance therapy more than halved their inhaler carbon footprint without loss of asthma control. The remaining inhaler carbon footprint could be reduced through switches from pMDI to DPI rescue medications or alternative lower-carbon footprint rescue inhalers if available. Asthma control improved in both groups, with greater control demonstrated in those initiated on FF/VI DPI. TRIAL REGISTRATION NUMBER: NCT01706198.

Carbon footprint impact of the choice of inhalers for asthma and COPD.

In the 1990s, metered dose inhalers (MDIs) containing chlorofluorocarbons were replaced with dry-powder inhalers (DPIs) and MDIs containing hydrofluorocarbons (HFCs). While HFCs are not ozone depleting, they are potent greenhouse gases. Annual carbon footprint (CO2e), per patient were 17 kg for Relvar-Ellipta/Ventolin-Accuhaler; and 439 kg for Seretide-Evohaler/Ventolin-Evohaler. In 2017, 70% of all inhalers sold in England were MDI, versus 13% in Sweden. Applying the Swedish DPI and MDI distribution to England would result in an annual reduction of 550 kt CO2e. The lower carbon footprint of DPIs should be considered alongside other factors when choosing inhalation devices.

Tenascin-C and alpha-smooth muscle actin positive cells are increased in the large airways in patients with COPD.

BACKGROUND: Chronic obstructive pulmonary disease (COPD) is characterized by inflammation and remodeling of the lungs. This results in alterations in extracellular matrix (ECM) and structural changes leading to airflow obstruction. We studied the expression of tenascin-C (Tn-C) and alpha smooth muscle actin (α-SMA), which act as a marker of myofibroblasts, in large airways from COPD patients. Our aim was to elucidate whether this expression correlated with smoking or with disease development. METHODS: Bronchoscopy was performed on 20 COPD patients (mean age 56 years; range 39-61; FEV1/FVC < 70% and FEV1 median 53% (range 33-69) of predicted). Age and smoking matched smokers (S) without COPD (n = 13) and age matched non-smokers (NS) (n = 14) served as controls. Bronchial mucosal biopsies were analyzed by immunohistochemistry. The distribution of Tn-C expression was assessed and graded in three levels, and the number of spindle shaped cells staining positive for α-SMA were counted. RESULTS: Biopsies from COPD patients had more (P < 0.001) Tn-C expression than the two control groups. A significantly (P < 0.05) increased number of spindle shaped cells expressing α-SMA was observed in COPD patients compared with the controls. Smokers and nonsmokers did not differ in this respect. The expression of Tn-C correlated positively (P < 0.001) to the number of α-SMA positive cells. CONCLUSIONS: We demonstrate increased expression of Tn-C and α-SMA positive cells in the large airways in COPD. This was not associated to smoking per se, but to the presence of airway obstruction. Our findings add new information regarding remodeling characteristics and highlight the large airways as a potential site for airways obstruction in COPD.

Agonist-specific patterns of beta 2-adrenoceptor responses in human airway cells during prolonged exposure.

BACKGROUND AND PURPOSE: Beta(2)-adrenoceptor agonists (beta(2)-agonists) are important bronchodilators used in the treatment of asthma and chronic obstructive pulmonary disease. At the molecular level, beta(2)-adrenergic agonist stimulation induces desensitization of the beta(2)-adrenoceptor. In this study, we have examined the relationships between initial effect and subsequent reduction of responsiveness to restimulation for a panel of beta(2)-agonists in cellular and in vitro tissue models. EXPERIMENTAL APPROACH: Beta(2)-adrenoceptor-induced responses and subsequent loss of receptor responsiveness were studied in primary human airway smooth muscle cells and bronchial epithelial cells by measuring cAMP production. Receptor responsiveness was compared at equi-effective concentrations, either after continuous incubation for 24 h or after a 1 h pulse exposure followed by a 23 h washout. Key findings were confirmed in guinea pig tracheal preparations in vitro. KEY RESULTS: There were differences in the reduction of receptor responsiveness in human airway cells and in vitro guinea pig trachea by a panel of beta(2)-agonists. When restimulation occurred immediately after continuous incubation, loss of responsiveness correlated with initial effect for all agonists. After the 1 h pulse exposure, differences between agonists emerged, for example isoprenaline and formoterol induced the least reduction of responsiveness. High lipophilicity was, to some extent, predictive of loss of responsiveness, but other factors appeared to be involved in determining the relationships between effect and subsequent loss of responsiveness for individual agonists. CONCLUSIONS AND IMPLICATIONS: There were clear differences in the ability of different beta(2) agonists to induce loss of receptor responsiveness at equi-effective concentrations.

Increased intraepithelial T-cells in stable COPD.

BACKGROUND: The airway epithelium is the first line of defence in the response to inhaled particles and irritants. Chronic obstructive pulmonary disease (COPD) is an inflammatory disease characterised by an irreversible loss of lung function, with cigarette smoking as a major risk factor. Here, we address intraepithelial T-cells in COPD, as these cells are a distinct T-cell subtype thought to have important regulatory functions. We hypothesised that intraepithelial T-cells play a role in the response to lung irritants and that the T-cell populations would be altered and associated with signs of inflammation in COPD. METHODS: Bronchoscopy with endobronchial mucosal biopsy sampling was performed in 22 patients (mean age; 57) with stable COPD (median FEV(1)% predicted: 51). Age- and smoking- matched smokers (S) with normal lung function (n=14) and age-matched non-smokers (NS) (n=15) served as controls. Airway inflammation was recorded visually using bronchitis index (BI). Biopsy specimens were processed into glycol methacrylate resin and inflammatory cells were stained immunohistochemically. RESULTS: The number of intraepithelial CD4+ T-cells were significantly higher in COPD patients compared to smokers as well as trend towards significance in non-smokers (p=0.005 and p=0.036, respectively), whereas intraepithelial CD8+ T-cells number were increased in patients with COPD compared to non-smokers (p=0.017). Both patients with COPD and smokers had a higher BI than non-smokers (p<0.001 for both). CONCLUSIONS: The present data suggest a role for intraepithelial CD4+ and CD8+ T-cells in stable COPD and indicate that T-cells are of importance in the long-term inflammatory response in COPD or, alternatively, play a regulatory role.

Detection of Chlamydia pneumoniae on cytospin preparations from bronchoalveolar lavage in COPD patients and in lung tissue from advanced emphysema.

Chronic obstructive pulmonary disease (COPD) is associated with smoking but other etiological factors contribute. Chlamydia pneumoniae is an obligate intracellular bacterium causing both acute and chronic respiratory tract infections. Studies have revealed an association between chronic C. pneumoniae infection and COPD, asthma and lung cancer but there have been difficulties detecting C. pneumoniae in the bronchial tree. Cytospin slides prepared from bronchoalveolar lavage (BAL) fluid from 14 patients with COPD, 10 healthy smokers (S) and 7 non smokers (NS) were analyzed with a fluorescein isothiocyanate labeled monoclonal antibody to C. pneumoniae. Lung tissue from 24 patients with advanced emphysema who had undergone lung volume reduction surgery (LVRS) was examined with immunohistochemistry for C. pneumoniae. Archived serum samples for detection of specific C. pneumoniae antibodies by microimmunofluorescence were available for 30 of the BAL subjects and 11 of LVRS patients. C. pneumoniae elementary body like structures were found in 29% of cytospin specimens from COPD patients, 14% of NS and 10% of HS. C. pneumoniae was detected in lung tissue in 8%. COPD patients had higher titres of IgG and IgA than NS and S. There was no association between occurrence of C. pneumoniae in BAL fluid and antibody titres. In conclusion, the assays used for detection of C. pneumoniae in lung tissue are feasible, and could be adapted in adequately powered studies to further confirm an association between C. pneumoniae infection and COPD.

Reduced intracellular oxygen radical production in whole blood leukocytes from COPD patients and asymptomatic smokers.

RATIONALE AND OBJECTIVES: COPD is characterized by irreversible airflow obstruction. It has, however, become clear that COPD also is a systemic disease. In the present study, we sought to investigate its impact on different peripheral leukocyte subpopulations that are recognized as important effector cells in the lung tissue. METHODS: We enrolled 20 patients with stable, moderate COPD (FEV1, 33 to 69%). Ten asymptomatic smokers and 10 nonsmokers served as control groups. Flow cytometry and whole blood analysis were used to minimize unwanted ex vivo modulation. Oxidative burst and adhesion molecule mobilization were analyzed on freshly drawn cells and after in vitro activation. MEASUREMENTS AND MAIN RESULTS: We found reduced oxidative burst in neutrophils, monocytes, and eosinophils after in vitro stimulation with tumor necrosis factor (TNF) and the bacterial peptide N-formyl-methionyl-leucyl-phenylalanine (fMLP) in both COPD patients and asymptomatic smokers as compared to nonsmoking control subjects. Vascular involvement was determined as increased soluble intercellular adhesion molecule-1 (sICAM-1) in the COPD group. There were no differences in adhesion molecule expression among the three groups. However, in COPD patients who had smoked the same morning prior to blood sampling, we found a reduced ability to mobilize adhesion molecule CD11b after TNF plus fMLP activation in all investigated cell types. "Acute" smoking did not significantly alter respiratory burst measurements. CONCLUSIONS: Both COPD patients and asymptomatic smokers have increased levels of sICAM-1 and a reduced intracellular oxidative burst in vitro, indicating a vascular endothelial activation and a possible state of refractoriness in circulating phagocytes in COPD. Although expression and mobilization of adhesion molecules were similar between groups, the acute smoke effect on CD11b points out the value of information on smoking behavior when analyzing function of peripheral inflammatory cells in a smoking population.