RIPK1 kinase-dependent inflammation and cell death contribute to the pathogenesis of COPD.

BACKGROUND: Receptor-interacting protein kinase 1 (RIPK1) is a key mediator of regulated cell death (including apoptosis and necroptosis) and inflammation, both drivers of COPD pathogenesis. We aimed to define the contribution of RIPK1 kinase-dependent cell death and inflammation in the pathogenesis of COPD. METHODS: We assessed RIPK1 expression in single-cell RNA sequencing (RNA-seq) data from human and mouse lungs, and validated RIPK1 levels in lung tissue of COPD patients via immunohistochemistry. Next, we assessed the consequences of genetic and pharmacological inhibition of RIPK1 kinase activity in experimental COPD, using Ripk1 S25D/S25D kinase-deficient mice and the RIPK1 kinase inhibitor GSK'547. RESULTS: RIPK1 expression increased in alveolar type 1 (AT1), AT2, ciliated and neuroendocrine cells in human COPD. RIPK1 protein levels were significantly increased in airway epithelium of COPD patients compared with never-smokers and smokers without airflow limitation. In mice, exposure to cigarette smoke (CS) increased Ripk1 expression similarly in AT2 cells, and further in alveolar macrophages and T-cells. Genetic and/or pharmacological inhibition of RIPK1 kinase activity significantly attenuated airway inflammation upon acute and subacute CS exposure, as well as airway remodelling, emphysema, and apoptotic and necroptotic cell death upon chronic CS exposure. Similarly, pharmacological RIPK1 kinase inhibition significantly attenuated elastase-induced emphysema and lung function decline. Finally, RNA-seq on lung tissue of CS-exposed mice revealed downregulation of cell death and inflammatory pathways upon pharmacological RIPK1 kinase inhibition. CONCLUSIONS: RIPK1 kinase inhibition is protective in experimental models of COPD and may represent a novel promising therapeutic approach.

Anti-Interleukin-5 Therapy Is Associated with Attenuated Lung Function Decline in Severe Eosinophilic Asthma Patients From the Belgian Severe Asthma Registry.

BACKGROUND: Asthmatics have accelerated lung function decline over time compared with healthy individuals. OBJECTIVE: To evaluate risk factors for accelerated lung function decline. METHODS: In a longitudinal analysis on severe asthmatics enrolled in the Belgian Severe Asthma Registry with at least 2 visits a minimum of 12 months apart, we compared characteristics of patients with and without decline (loss of post-bronchodilation forced expiratory volume in 1 s [FEV1] (% predicted)/y greater than zero) over time. Multiple linear regression was applied to study the factors independently associated with FEV1 decline. RESULTS: In the overall population (n = 318), median annual FEV1 decline was 0.27 (-4.22 to 3.80) % predicted/y over a period of 23 months (12-41 months). Asthma was less controlled at baseline in nondecliners than in decliners (53%). Lung function and residual volume at baseline were higher in the declining group. Decliners presented with increased bronchial reactivity (ie, a lower provocative concentration of methacholine causing a 20% fall in FEV1) at baseline. Twenty-five percent of nondecliners were started on anti-interleukin-5 (anti-IL-5) for severe eosinophilic asthma during the study compared with 10% of decliners. The multivariable model suggested that Asthma Control Questionnaire score at baseline, late-onset asthma, and addition of anti-IL-5 during follow-up were associated with lower FEV1 decline, independently from other variables such as evolution in exacerbations, smoking status, inhaled corticosteroids or oral corticosteroids dose, or add-on anti-immunoglobulin E over time, whereas reversibility to salbutamol and higher FEV1 were associated with accelerated FEV1 decline. CONCLUSIONS: Add-on therapy with anti-IL-5 in severe eosinophilic asthma was associated with an attenuated FEV1 decline. The causality of this observation should, however, be confirmed in future prospective controlled studies.

MiR-223 is increased in lungs of patients with COPD and modulates cigarette smoke-induced pulmonary inflammation.

Since microRNA (miR)-223-3p modulates inflammatory responses and chronic obstructive pulmonary disease (COPD) is associated with amplified pulmonary inflammation, we hypothesized that miR-223-3p plays a role in COPD pathogenesis. Expression of miR-223-3p was measured in lung tissue of two independent cohorts with patients with GOLD stage II-IV COPD, never smokers, and smokers without COPD. The functional role of miR-223-3p was studied in deficient mice and on overexpression in airway epithelial cells from COPD and controls. We observed higher miR-223-3p levels in patients with COPD stage II-IV compared with (non)-smoking controls, and levels were associated with higher neutrophil numbers in bronchial biopsies of patients with COPD. MiR-223-3p expression was also increased in lungs and bronchoalveolar lavage of cigarette smoke (CS)-exposed mice. CS-induced neutrophil and monocyte lung infiltration was stronger in miR-223-deficient mice on acute (5 days) exposure, but attenuated on subchronic (4 wk) exposure. Additionally, miR-223 deficiency attenuated acute and subchronic CS-induced lung infiltration of dendritic cells and T lymphocytes. Finally, in vitro overexpression of miR-223-3p in non-COPD airway epithelial cells suppressed C-X-C motif chemokine ligand 8 (CXCL8) and granulocyte monocyte-colony stimulation factor (GM-CSF) secretion and gene expression of the proinflammatory transcription factor TRAF6. Importantly, this suppressive effect of miR-223-3p was compromised in COPD-derived cultures. In conclusion, we demonstrate that miR-223-3p is increased in lungs of patients with COPD and CS-exposed mice and is associated with neutrophilic inflammation. In vivo data indicate that miR-223 acts as negative regulator of acute CS-induced neutrophilic and monocytic inflammation. In vitro data suggest that miR-223-3p does so by suppressing proinflammatory airway epithelial responses, which is less effective in COPD epithelium.

Quantification and role of innate lymphoid cell subsets in Chronic Obstructive Pulmonary Disease.

OBJECTIVES: Innate lymphoid cells (ILCs) secrete cytokines, such as IFN-γ, IL-13 and IL-17, which are linked to chronic obstructive pulmonary disease (COPD). Here, we investigated the role of pulmonary ILCs in COPD pathogenesis. METHODS: Lung ILC subsets in COPD and control subjects were quantified using flow cytometry and associated with clinical parameters. Tissue localisation of ILC and T-cell subsets was determined by immunohistochemistry. Mice were exposed to air or cigarette smoke (CS) for 1, 4 or 24 weeks to investigate whether pulmonary ILC numbers and activation are altered and whether they contribute to CS-induced innate inflammatory responses. RESULTS: Quantification of lung ILC subsets demonstrated that ILC1 frequency in the total ILC population was elevated in COPD and was associated with smoking and severity of respiratory symptoms (COPD Assessment Test [CAT] score). All three ILC subsets localised near lymphoid aggregates in COPD. In the COPD mouse model, CS exposure in C57BL/6J mice increased ILC numbers at all time points, with relative increases in ILC1 in bronchoalveolar lavage (BAL) fluid. Importantly, CS exposure induced increases in neutrophils, monocytes and dendritic cells that remained elevated in Rag2/Il2rg-deficient mice that lack adaptive immune cells and ILCs. However, CS-induced CXCL1, IL-6, TNF-α and IFN-γ levels were reduced by ILC deficiency. CONCLUSION: The ILC1 subset is increased in COPD patients and correlates with smoking and severity of respiratory symptoms. ILCs also increase upon CS exposure in C57BL/6J mice. In the absence of adaptive immunity, ILCs contribute to CS-induced pro-inflammatory mediator release, but are redundant in CS-induced innate inflammation.

Expression of ACE2, the SARS-CoV-2 Receptor, in Lung Tissue of Patients With Type 2 Diabetes.

Increased expression of pulmonary ACE2, the SARS-CoV-2 receptor, could contribute to increased infectivity of COVID-19 in patients with diabetes, but ACE2 expression has not been studied in lung tissue of subjects with diabetes. We therefore studied ACE2 mRNA and protein expression in lung tissue samples of subjects with and without diabetes that were collected between 2002 and 2020 from patients undergoing lobectomy for lung tumors. For RT-PCR analyses, samples from 15 subjects with diabetes were compared with 91 randomly chosen control samples. For immunohistochemical staining, samples from 26 subjects with diabetes were compared with 66 randomly chosen control samples. mRNA expression of ACE2 was measured by quantitative RT-PCR. Protein levels of ACE2 were visualized by immunohistochemistry on paraffin-embedded lung tissue samples and quantified in alveolar and bronchial epithelium. Pulmonary ACE2 mRNA expression was not different between subjects with or without diabetes. In contrast, protein levels of ACE2 were significantly increased in both alveolar tissue and bronchial epithelium of patients with diabetes compared with control subjects, independent of smoking, chronic obstructive pulmonary disease, BMI, renin-angiotensin-aldosterone system inhibitor use, and other potential confounders. To conclude, we show increased bronchial and alveolar ACE2 protein expression in patients with diabetes. Further research is needed to elucidate whether upregulation of ACE2 expression in airways and lungs has consequences on infectivity and clinical outcomes of COVID-19.

Earlier palliative home care is associated with patient-centred medical resource utilisation and lower costs in the last 30†days before death in COPD: a population-level decedent cohort study.

COPD patients often use many medical resources, such as hospital admissions and medical imaging, inappropriately close to death. Palliative home care (PHC) could beneficially affect this. The aim was to study the effect of use and timing of PHC on medical resource use and costs in the last 30 days before death (DBD) for COPD.We performed a retrospective study of all Belgian decedents in 2010-2015 with COPD and a primary cause of death being COPD or cardiovascular diseases. Odds ratios for medical resources were calculated between using and four PHC timing categories (>360, 360-181, 180-91 and 90-31 DBD) versus not using. Confounders were socio-demographic, care intensity and disease severity variables.Of the 58 527 decedents with COPD, 644 (1.1%) patients received PHC earlier than 30 DBD. Using PHC (versus not using) decreased the odds ratio for hospitalisation (0.35), intensive care unit admission (0.16), specialist contacts (0.58), invasive ventilation (0.13), medical imaging including chest radiograph (0.34), sedatives (0.48) and hospital death (0.14). It increased the odds ratio for home care (3.27), general practitioner contact (4.65), palliative care unit admission (2.61), noninvasive ventilation (2.65), gastric tube (2.15), oxygen (2.22) and opioids (4.04) (p<0.001). Mean total healthcare costs were €1569 lower for using PHC. All PHC timing categories showed a benefit in medical resource use and costs. However, we observed the largest benefit in the category PHC 90-31 DBD.Health policy and services should focus on increasing PHC access, while research should further explore early PHC initiation for COPD.

Early Integrated Palliative Home Care and Standard Care for End-Stage COPD (EPIC): A Phase II Pilot RCT Testing Feasibility, Acceptability, and Effectiveness.

CONTEXT: Although early integrated palliative home care (PHC) is believed to be beneficial for patients with chronic obstructive pulmonary disease (COPD), trials testing this hypothesis are rare and show inconclusive results. OBJECTIVES: To test feasibility, acceptability, and preliminary effectiveness of early integrated PHC for end-stage COPD. METHODS: Testing a six-month early integrated PHC pilot randomized controlled trial given by palliative home care nurses (PHCNs) for end-stage COPD with five components: 1) preinclusion COPD support training for PHCNs; 2) monthly PHC visits; 3) leaflets on coping mechanisms; 4) a protocol on symptom management and support, a care plan and an action plan; and 5) integration of PHC and usual care through reporting and communication mechanisms. Patient-reported outcomes were assessed six times weekly. Participants and health care professionals involved were interviewed. RESULTS: Of 70 eligible patients, 39 (56%) participated (20:19 intervention vs control group) and 64% completed the trial. A patient received on average 3.4 PHC visits, mainly for disease insight, symptom management, and care planning. Nurses distributed all reports but hardly connected with health professionals except general practitioners (GPs); eight of 10 interviewed patients referred to the psychosocial support, breathing exercises, and care decisions as helpful. Some GPs criticized PHC being given too early, but pulmonologists and PHCNs did not. Effectiveness analysis showed no overall intervention effect for the outcomes, but between baseline and week 24, fewer hospitalizations in the control group (P = 0.03) and a trend of higher perceived quality of care in the intervention group (P = 0.06) were found. A clinically relevant difference was observed at week 24 for health-related quality of life in favor of the control group. CONCLUSION: Our intervention on early integrated PHC for end-stage COPD is feasible and accepted but did not yield the anticipated preliminary effectiveness. Before moving to a Phase III trial, enhanced coordination of care, more GP involvement, more intensive training for PHCNs in COPD support, and revision of the trial design, for example, of targeted outcomes in line with individual patient goals and care preferences should be done.

EUFOREA consensus on biologics for CRSwNP with or without asthma.

Novel therapies such as type 2 targeting biologics are emerging treatment options for patients with chronic inflammatory respiratory diseases, fulfilling the needs of severely uncontrolled patients. The majority of patients with chronic rhinosinusitis with nasal polyps (CRSwNP) and over half of patients with asthma show a type 2 inflammatory signature in sinonasal mucosa and/or lungs. Importantly, both chronic respiratory diseases are frequent comorbidities, ensuring alleviation of both upper and lower airway pathology by systemic biological therapy. Type 2-targeting biologics such as anti-IgE, anti-IL4Rα, anti-IL5, and anti-IL5Rα have entered the market for selected pheno/endotypes of asthma patients and may soon also become available for CRSwNP patients. Given the high prevalence of chronic respiratory diseases and the high cost associated with biologics, patient selection is crucial in order to implement such therapies into chronic respiratory disease care pathways. The European Forum for Research and Education in Allergy and Airway Diseases (EUFOREA) organized a multidisciplinary Expert Board Meeting to discuss the positioning of biologics into the care pathways for CRSwNP patients with and without comorbid asthma.

ERS technical standard on bronchial challenge testing: pathophysiology and methodology of indirect airway challenge testing.

Recently, this international task force reported the general considerations for bronchial challenge testing and the performance of the methacholine challenge test, a "direct" airway challenge test. Here, the task force provides an updated description of the pathophysiology and the methods to conduct indirect challenge tests. Because indirect challenge tests trigger airway narrowing through the activation of endogenous pathways that are involved in asthma, indirect challenge tests tend to be specific for asthma and reveal much about the biology of asthma, but may be less sensitive than direct tests for the detection of airway hyperresponsiveness. We provide recommendations for the conduct and interpretation of hyperpnoea challenge tests such as dry air exercise challenge and eucapnic voluntary hyperpnoea that provide a single strong stimulus for airway narrowing. This technical standard expands the recommendations to additional indirect tests such as hypertonic saline, mannitol and adenosine challenge that are incremental tests, but still retain characteristics of other indirect challenges. Assessment of airway hyperresponsiveness, with direct and indirect tests, are valuable tools to understand and to monitor airway function and to characterise the underlying asthma phenotype to guide therapy. The tests should be interpreted within the context of the clinical features of asthma.

Development of a complex intervention for early integration of palliative home care into standard care for end-stage COPD patients: A Phase 0-I study.

BACKGROUND: Research suggests that palliative home care should be integrated early into standard care for end-stage COPD patients. Patients also express the wish to be cared for and to die at home. However, a practice model for early integration of palliative home care (PHC) into standard care for end-stage COPD has not been fully developed. AIM: To develop an intervention for early integration of PHC into standard care for end-stage COPD patients. METHODS: We conducted a Phase 0-I study according to the Medical Research Council Framework for the development of complex interventions. Phase 0 aimed to identify the inclusion criteria and key components of the intervention by way of an explorative literature search of interventions, expert consultations, and seven focus groups with general practitioners and community nurses on perceived barriers to and facilitators of early integrated PHC for COPD. In Phase 1, the intervention, its inclusion criteria and its components were developed and further refined by an expert panel and two expert opinions. RESULTS: Phase 0 resulted in identification of inclusion criteria and components from existing interventions, and barriers to and facilitators of early integration of PHC for end-stage COPD. Based on these findings, a nurse-led intervention was developed in Phase I consisting of training for PHC nurses in symptom recognition and physical therapy exercises for end-stage COPD, regular visits by PHC nurses at the patients' homes, two information leaflets on self-management, a semi-structured protocol and follow-up plan to record the outcomes of the home visits, and integration of care by enabling collaboration and communication between home and hospital-based professional caregivers. CONCLUSION: This Phase 0-I trial succeeded in developing a complex intervention for early integration of PHC for end-stage COPD. The use of three methods in Phase 0 gave reliable data on which to base inclusion criteria and components of the intervention. The preliminary effectiveness, feasibility and acceptability of the intervention will be subsequently tested in a Phase II study.

"A palliative end-stage COPD patient does not exist": a qualitative study of barriers to and facilitators for early integration of palliative home care for end-stage COPD.

Early integration of palliative home care (PHC) might positively affect people with chronic obstructive pulmonary disease (COPD). However, PHC as a holistic approach is not well integrated in clinical practice at the end-stage COPD. General practitioners (GPs) and community nurses (CNs) are highly involved in primary and home care and could provide valuable perspectives about barriers to and facilitators for early integrated PHC in end-stage COPD. Three focus groups were organised with GPs (n = 28) and four with CNs (n = 28), transcribed verbatim and comparatively analysed. Barriers were related to the unpredictability of COPD, a lack of disease insight and resistance towards care of the patient, lack of cooperation and experience with PHC for professional caregivers, lack of education about early integrated PHC, insufficient continuity of care from hospital to home, and lack of communication about PHC between professional caregivers and with end-stage COPD patients. Facilitators were the use of trigger moments for early integrating PHC, such as after a hospital admission or when an end-stage COPD patient becomes oxygen-dependent or housebound, positive attitudes towards PHC in informal caregivers, more focus on early integration of PHC in professional caregivers' education, implementing advance care planning in healthcare and PHC systems, and enhancing communication about care and PHC. The results provide insights for clinical practice and the development of key components for successful practice in a phase 0-2 Early Integration of PHC for end-stage COPD (EPIC) trial, such as improving care integration, patients' disease insight and training PHC nurses in care for end-stage COPD.

DPP4, the Middle East Respiratory Syndrome Coronavirus Receptor, is Upregulated in Lungs of Smokers and Chronic Obstructive Pulmonary Disease Patients.

Background: Middle East respiratory syndrome coronavirus (MERS-CoV) causes pneumonia with a relatively high case fatality rate in humans. Smokers and chronic obstructive pulmonary disease (COPD) patients have been reported to be more susceptible to MERS-CoV infection. Here, we determined the expression of MERS-CoV receptor, dipeptidyl peptidase IV (DPP4), in lung tissues of smokers without airflow limitation and COPD patients in comparison to nonsmoking individuals (never-smokers). Methods: DPP4 expression was measured in lung tissue of lung resection specimens of never-smokers, smokers without airflow limitation, COPD GOLD stage II patients and in lung explants of end-stage COPD patients. Both control subjects and COPD patients were well phenotyped and age-matched. The mRNA expression was determined using qRT-PCR and protein expression was quantified using immunohistochemistry. Results: In smokers and subjects with COPD, both DPP4 mRNA and protein expression were significantly higher compared to never-smokers. Additionally, we found that both DPP4 mRNA and protein expression were inversely correlated with lung function and diffusing capacity parameters. Conclusions: We provide evidence that DPP4 is upregulated in the lungs of smokers and COPD patients, which could partially explain why these individuals are more susceptible to MERS-CoV infection. These data also highlight a possible role of DPP4 in COPD pathogenesis.

microRNA profiling in lung tissue and bronchoalveolar lavage of cigarette smoke-exposed mice and in COPD patients: a translational approach.

Chronic obstructive pulmonary disease (COPD) is characterized by a progressive airflow limitation and is associated with a chronic inflammatory response in both airways and lungs. microRNAs (miRNAs) are often highly conserved between species and have an intricate role within homeostatic conditions and immune responses. Also, miRNAs are dysregulated in smoking-associated diseases. We investigated the miRNA profile of 523 miRNAs by stem-loop RT-qPCR in lung tissue and cell-free bronchoalveolar lavage (BAL) supernatant of mice exposed to air or cigarette smoke (CS) for 4 or 24 weeks. After 24 weeks of CS exposure, 31 miRNAs were differentially expressed in lung tissue and 78 in BAL supernatant. Next, we correlated the miRNA profiling data to inflammation in BAL and lung, obtained by flow cytometry or ELISA. In addition, we surveyed for overlap with newly assessed miRNA profiles in bronchial biopsies and with previously assessed miRNA profiles in lung tissue and induced sputum supernatant of smokers with COPD. Several miRNAs showed concordant differential expression between both species including miR-31*, miR-155, miR-218 and let-7c. Thus, investigating miRNA profiling data in different compartments and both species provided accumulating insights in miRNAs that may be relevant in CS-induced inflammation and the pathogenesis of COPD.

Role of tumor necrosis factor-α and its receptors in diesel exhaust particle-induced pulmonary inflammation.

Inhalation of diesel exhaust particles (DEP) induces an inflammatory reaction in the lung. However, the underlying mechanisms remain to be elucidated. Tumor necrosis factor alpha (TNF-α) is a pro-inflammatory cytokine that operates by binding to tumor necrosis factor receptor 1 (TNFR1) and tumor necrosis factor receptor 2 (TNFR2). The role of TNF-α signaling and the importance of either TNFR1 or TNFR2 in the DEP-induced inflammatory response has not yet been elucidated. TNF-α knockout (KO), TNFR1 KO, TNFR2 KO, TNFR1/TNFR2 double KO (TNFR-DKO) and wild type (WT) mice were intratracheally exposed to saline or DEP. Pro-inflammatory cells and cytokines were assessed in the bronchoalveolar lavage fluid (BALF). Exposure to DEP induced a dose-dependent inflammation in the BALF in WT mice. In addition, levels of TNF-α and its soluble receptors were increased upon exposure to DEP. The DEP-induced inflammation in the BALF was decreased in TNF-α KO, TNFR-DKO and TNFR2 KO mice. In contrast, the inflammatory response in the BALF of DEP-exposed TNFR1 KO mice was largely comparable with WT controls. In conclusion, these data provide evidence for a regulatory role of TNF-α in DEP-induced pulmonary inflammation and identify TNFR2 as the most important receptor in mediating these inflammatory effects.

Epidemiology and impact of chronic bronchitis in chronic obstructive pulmonary disease.

Research on the association between chronic bronchitis and chronic obstructive pulmonary disease (COPD) exacerbations has led to discordant results. Furthermore, the impact of chronic bronchitis on mortality in COPD subjects is unclear.Within the Rotterdam Study, a population-based cohort study of subjects aged ≥45 years, chronic bronchitis was defined as having a productive cough for ≥3 months per year for two consecutive years. Linear, logistic regression and Cox proportional hazard models were adjusted for age, sex and pack-years.Out of 972 included COPD subjects, 752 had no chronic phlegm production (CB-) and 220 had chronic phlegm production, of whom 172 met the definition of chronic bronchitis (CB+). CB+ subjects were older, more frequently current smokers and had more pack-years than CB- subjects. During a median 6.5 years of follow-up, CB+ subjects had greater decline in lung function (-38 mL·year-1, 95% CI -61.7--14.6; p=0.024). CB+ subjects had an increased risk of frequent exacerbations (OR 4.0, 95% CI 2.7-5.9; p<0.001). In females, survival was significantly worse in CB+ subjects compared to CB- subjects. Regarding cause-specific mortality, CB+ subjects had an increased risk of respiratory mortality (hazard ratio 2.16, 95% CI 1.12-4.17; p=0.002).COPD subjects with chronic bronchitis have an increased risk of exacerbations and respiratory mortality compared to COPD subjects without chronic phlegm production.

Dysregulation of type 2 innate lymphoid cells and TH2 cells impairs pollutant-induced allergic airway responses.

BACKGROUND: Although the prominent role of TH2 cells in type 2 immune responses is well established, the newly identified type 2 innate lymphoid cells (ILC2s) can also contribute to orchestration of allergic responses. Several experimental and epidemiologic studies have provided evidence that allergen-induced airway responses can be further enhanced on exposure to environmental pollutants, such as diesel exhaust particles (DEPs). However, the components and pathways responsible remain incompletely known. OBJECTIVE: We sought to investigate the relative contribution of ILC2 and adaptive TH2 cell responses in a murine model of DEP-enhanced allergic airway inflammation. METHODS: Wild-type, Gata-3+/nlslacZ (Gata-3-haploinsufficient), RAR-related orphan receptor α (RORα)fl/flIL7RCre (ILC2-deficient), and recombination-activating gene (Rag) 2-/- mice were challenged with saline, DEPs, or house dust mite (HDM) or DEP+HDM. Airway hyperresponsiveness, as well as inflammation, and intracellular cytokine expression in ILC2s and TH2 cells in the bronchoalveolar lavage fluid and lung tissue were assessed. RESULTS: Concomitant DEP+HDM exposure significantly enhanced allergic airway inflammation, as characterized by increased airway eosinophilia, goblet cell metaplasia, accumulation of ILC2s and TH2 cells, type 2 cytokine production, and airway hyperresponsiveness compared with sole DEPs or HDM. Reduced Gata-3 expression decreased the number of functional ILC2s and TH2 cells in DEP+HDM-exposed mice, resulting in an impaired DEP-enhanced allergic airway inflammation. Interestingly, although the DEP-enhanced allergic inflammation was marginally reduced in ILC2-deficient mice that received combined DEP+HDM, it was abolished in DEP+HDM-exposed Rag2-/- mice. CONCLUSION: These data indicate that dysregulation of ILC2s and TH2 cells attenuates DEP-enhanced allergic airway inflammation. In addition, a crucial role for the adaptive immune system was shown on concomitant DEP+HDM exposure.

MicroRNA Profiling Reveals a Role for MicroRNA-218-5p in the Pathogenesis of Chronic Obstructive Pulmonary Disease.

RATIONALE: Aberrant expression of microRNAs (miRNAs) can have a detrimental role in disease pathogenesis. OBJECTIVES: To identify dysregulated miRNAs in lung tissue of patients with chronic obstructive pulmonary disease (COPD). METHODS: We performed miRNA and mRNA profiling using high throughput stem-loop reverse-transcriptase quantitative polymerase chain reaction and mRNA microarray, respectively, on lung tissue of 30 patients (screening cohort) encompassing 8 never-smokers, 10 smokers without airflow limitation, and 12 smokers with COPD. Differential expression of miRNA-218-5p (miR-218-5p) was validated by reverse-transcriptase quantitative polymerase chain reaction in an independent cohort of 71 patients, an in vivo murine model of COPD, and primary human bronchial epithelial cells. Localization of miR-218-5p was assessed by in situ hybridization. In vitro and in vivo perturbation of miR-218-5p combined with RNA sequencing and gene set enrichment analysis was used to elucidate its functional role in COPD pathogenesis. MEASUREMENTS AND MAIN RESULTS: Several miRNAs were differentially expressed among the different patient groups. Interestingly, miR-218-5p was significantly down-regulated in smokers without airflow limitation and in patients with COPD compared with never-smokers. Decreased pulmonary expression of miR-218-5p was validated in an independent validation cohort, in cigarette smoke-exposed mice, and in human bronchial epithelial cells. Importantly, expression of miR-218-5p strongly correlated with airway obstruction. Furthermore, cellular localization of miR-218-5p in human and murine lung revealed highest expression of miR-218-5p in the bronchial airway epithelium. Perturbation experiments with a miR-218-5p mimic or inhibitor demonstrated a protective role of miR-218-5p in cigarette smoke-induced inflammation and COPD. CONCLUSIONS: We highlight a role for miR-218-5p in the pathogenesis of COPD.