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.

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.

Innate lymphoid cells in isocyanate-induced asthma: role of microRNA-155.

BACKGROUND: Occupational asthma, induced by workplace exposures to low molecular weight agents such as toluene 2,4-diisocyanate (TDI), causes a significant burden to patients and society. Little is known about innate lymphoid cells (ILCs) in TDI-induced asthma. A critical regulator of ILC function is microRNA-155, a microRNA associated with asthma. OBJECTIVE: To determine whether TDI exposure modifies the number of ILCs in the lung and whether microRNA-155 contributes to TDI-induced airway inflammation and hyperresponsiveness. METHODS: C57BL/6 wild-type and microRNA-155 knockout mice were sensitised and challenged with TDI or vehicle. Intracellular cytokine expression in ILCs and T-cells was evaluated in bronchoalveolar lavage (BAL) fluid using flow cytometry. Peribronchial eosinophilia and goblet cells were evaluated on lung tissue, and airway hyperresponsiveness was measured using the forced oscillation technique. Putative type 2 ILCs (ILC2) were identified in bronchial biopsies of subjects with TDI-induced occupational asthma using immunohistochemistry. Human bronchial epithelial cells were exposed to TDI or vehicle. RESULTS: TDI-exposed mice had higher numbers of airway goblet cells, BAL eosinophils, CD4+ T-cells and ILCs, with a predominant type 2 response, and tended to have airway hyperresponsiveness. In TDI-exposed microRNA-155 knockout mice, inflammation and airway hyperresponsiveness were attenuated. TDI exposure induced IL-33 expression in human bronchial epithelial cells and in murine lungs, which was microRNA-155 dependent in mice. GATA3+CD3- cells, presumably ILC2, were present in bronchial biopsies. CONCLUSION: TDI exposure is associated with increased numbers of ILCs. The proinflammatory microRNA-155 is crucial in a murine model of TDI asthma, suggesting its involvement in the pathogenesis of occupational asthma due to low molecular weight agents.

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.

IL-33 signalling contributes to pollutant-induced allergic airway inflammation.

BACKGROUND: Clinical and experimental studies have identified a crucial role for IL-33 and its receptor ST2 in allergic asthma. Inhalation of traffic-related pollutants, such as diesel exhaust particles (DEP), facilitates the development of asthma and can cause exacerbations of asthma. However, it is unknown whether IL-33/ST2 signalling contributes to the enhancing effects of air pollutants on allergic airway responses. OBJECTIVE: We aim to investigate the functional role of IL-33/ST2 signalling in DEP-enhanced allergic airway responses, using an established murine model. METHODS: C57BL/6J mice were exposed to saline, DEP alone, house dust mite (HDM) alone or combined DEP+HDM. To inhibit IL-33 signalling, recombinant soluble ST2 (r-sST2) was given prophylactically (ie, during the whole experimental protocol) or therapeutically (ie, at the end of the experimental protocol). Airway hyperresponsiveness and the airway inflammatory responses were assessed in bronchoalveolar lavage fluid (BALF) and lung. RESULTS: Combined exposure to DEP+HDM increased IL-33 and ST2 expression in lung, elevated inflammatory responses and bronchial hyperresponsiveness compared to saline, sole DEP or sole HDM exposure. Prophylactic interference with the IL-33/ST2 signalling pathway impaired the DEP-enhanced allergic airway inflammation in the BALF, whereas effects on lung inflammation and airway hyperresponsiveness were minimal. Treatment with r-sST2 at the end of the experimental protocol did not modulate the DEP-enhanced allergic airway responses. CONCLUSION: Our data suggest that the IL-33/ST2 pathway contributes to the onset of DEP-enhanced allergic airway inflammation.

Pro- and Anti-Inflammatory Role of ChemR23 Signaling in Pollutant-Induced Inflammatory Lung Responses.

Inhalation of traffic-related particulate matter (e.g., diesel exhaust particles [DEPs]) is associated with acute inflammatory responses in the lung, and it promotes the development and aggravation of allergic airway diseases. We previously demonstrated that exposure to DEP was associated with increased recruitment and maturation of monocytes and conventional dendritic cells (DCs), resulting in TH2 polarization. Monocytes and immature DCs express the G-protein coupled receptor chemR23, which binds the chemoattractant chemerin. Using chemR23 knockout (KO) and corresponding wild-type (WT) mice, we determined the role of chemR23 signaling in response to acute exposure to DEPs and in response to DEP-enhanced house dust mite (HDM)-induced allergic airway inflammation. Exposure to DEP alone, as well as combined exposure to DEP plus HDM, elevated the levels of chemerin in the bronchoalveolar lavage fluid of WT mice. In response to acute exposure to DEPs, monocytes and monocyte-derived DCs accumulated in the lungs of WT mice, but this response was significantly attenuated in chemR23 KO mice. Concomitant exposure to DEP plus HDM resulted in allergic airway inflammation with increased eosinophilia, goblet cell metaplasia, and TH2 cytokine production in WT mice, which was further enhanced in chemR23 KO mice. In conclusion, we demonstrated an opposing role for chemR23 signaling depending on the context of DEP-induced inflammation. The chemR23 axis showed proinflammatory properties in a model of DEP-induced acute lung inflammation, in contrast to anti-inflammatory effects in a model of DEP-enhanced allergic airway inflammation.

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.

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.

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.

Alcohol hyper-responsiveness in chronic rhinosinusitis with nasal polyps.

BACKGROUND: An important percentage of subjects diagnosed with chronic upper airway disease report alcohol-induced worsening of their symptoms. The prevalence and characteristics of respiratory reactions provoked by alcohol-containing drinks have not been fully investigated yet. OBJECTIVE: The aim of this study was to estimate the prevalence and characteristics of alcohol hyper-responsiveness in patients with chronic airway disease and healthy controls. Furthermore, nasal inflammation was evaluated in nasal polyp patients with and without hyper-responsiveness. METHODS: We evaluated the prevalence and characteristics of alcohol-induced respiratory complaints in 1281 subjects. Chronic rhinosinusitis with nasal polyps (CRSwNP) patients with and without NSAID exacerbated respiratory disease (NERD), chronic rhinosinusitis patients without nasal polyps (CRSsNP), allergic rhinitis (AR) patients and healthy controls were approached by means of a questionnaire. Inflammatory markers (eosinophilic cationic protein (ECP), IL-5, IgE, SAE-specific IgE, IL-17, TNFα and IFNγ) in tissue were then compared between alcohol hyper-responsive and non-hyper-responsive CRSwNP patients. RESULTS: The highest prevalence of nasal and bronchial alcohol hyper-responsiveness was observed in patients with NERD, followed by CRSwNP, and less frequent in CRSsNP, AR and healthy controls. Alcohol hyper-responsiveness is significantly more prevalent in CRSwNP patients suffering from recurrent disease and in patients with severe symptomatology. In nasal tissue of the hyper-responsive CRSwNP group, we observed significantly higher nasal levels of the eosinophilic biomarker ECP. CONCLUSION AND CLINICAL RELEVANCE: Nasal hyper-responsiveness to alcohol is significantly more prevalent in severe eosinophilic upper airway disease.

Chronic Obstructive Pulmonary Disease and the Risk of Stroke. The Rotterdam Study.

RATIONALE: Worldwide, chronic obstructive pulmonary disease (COPD) and stroke are leading causes of death. Increasing evidence suggests an association between both diseases, either caused by an increased atherosclerosis risk in patients with COPD or as a consequence of shared risk factors between stroke and COPD. OBJECTIVES: To examine the associations between COPD and subtypes of stroke in the general population and to explore the role of cardiovascular risk factors and exacerbations on these associations. METHODS: Within the prospective population-based Rotterdam Study, we followed 13,115 participants without history of stroke for occurrence of stroke. Follow up started in 1990 to 2008 and ended in 2012. COPD was related to stroke using a time-dependent Cox proportional hazard model. MEASUREMENTS AND MAIN RESULTS: COPD was diagnosed in 1,566 participants. During 126,347 person-years, 1,250 participants suffered a stroke, of which 701 were ischemic and 107 hemorrhagic. Adjusted for age, age squared, and sex, COPD was significantly associated with all stroke (hazard ratio [HR], 1.20; 95% confidence interval, 1.00-1.43), ischemic stroke (HR, 1.27; 1.02-1.59), and hemorrhagic stroke (HR, 1.70; 1.01-2.84). Adjusting for cardiovascular risk factors gave similar effect sizes. In contrast, additional adjusting for smoking attenuated the effect sizes: HR, 1.09 (0.91-1.31) for all stroke; HR, 1.13 (0.91-1.42) for ischemic stroke; and HR 1.53 (0.91-2.59) for hemorrhagic stroke. After an acute severe exacerbation, subjects with COPD had a 6.66-fold (2.42-18.20) increased risk of stroke. CONCLUSIONS: Our cohort study demonstrated a higher risk of both ischemic and hemorrhagic stroke in subjects with COPD and revealed the importance of smoking as a shared risk factor.

Asthma inflammatory phenotypes show differential microRNA expression in sputum.

BACKGROUND: Asthma is classified according to severity and inflammatory phenotype and is likely to be distinguished by specific microRNA (miRNA) expression profiles. OBJECTIVE: We sought to associate miRNA expression in sputum supernatants with the inflammatory cell profile and disease severity in asthmatic patients. METHODS: We investigated miRNA expression in sputum supernatants of 10 healthy subjects, 17 patients with mild-to-moderate asthma, and 9 patients with severe asthma using high-throughput, stem-loop, reverse transcriptase quantitative real-time PCR miRNA expression profiling (screening cohort, n = 36). Differentially expressed miRNAs were validated in an independent cohort (n = 60; 10 healthy subjects and 50 asthmatic patients). Cellular miRNA origin was examined by using in situ hybridization and reverse transcriptase quantitative real-time PCR. The functional role of miRNAs was assessed by using in silico analysis and in vitro transfecting miRNA mimics in human bronchial epithelial cells. RESULTS: In 2 independent cohorts expression of miR-629-3p, miR-223-3p, and miR-142-3p was significantly upregulated in sputum of patients with severe asthma compared with that in healthy control subjects and was highest in patients with neutrophilic asthma. Expression of the 3 miRNAs was associated with sputum neutrophilia, and miR-223-3p and miR-142-3p expression was associated also with airway obstruction (FEV1/forced vital capacity). Expression of miR-629-3p was localized in the bronchial epithelium, whereas miR-223-3p and miR-142-3p were expressed in neutrophils, monocytes, and macrophages. Transfecting human bronchial epithelial cells with miR-629-3p mimic induced epithelial IL-8 mRNA and protein expression. IL-1ß and IL-8 protein levels were significantly increased in sputum of patients with severe asthma and were positively associated with sputum neutrophilia. CONCLUSIONS: Expression of miR-223-3p, miR-142-3p, and miR-629-3p is increased in sputum of patients with severe asthma and is linked to neutrophilic airway inflammation, suggesting that these miRNAs contribute to this asthma inflammatory phenotype.

Role of B Cell-Activating Factor in Chronic Obstructive Pulmonary Disease.

RATIONALE: B cell-activating factor (BAFF) plays a major role in activation of B cells and in adaptive humoral immune responses. In chronic obstructive pulmonary disease (COPD), lymphoid follicles have been associated with disease severity, and overexpression of BAFF has been demonstrated within lymphoid follicles of patients with severe COPD. OBJECTIVES: To investigate expression and localization of BAFF in the lungs of patients with COPD and to study the role of BAFF in COPD by antagonizing BAFF in a mouse model of chronic cigarette smoke (CS) exposure. METHODS: We quantified and localized BAFF expression in lungs of never-smokers, smokers without COPD, and patients with COPD and in lungs of air- or CS-exposed mice by reverse-transcriptase polymerase chain reaction, ELISA, immunohistochemistry, and confocal imaging. Next, to investigate the role of BAFF in COPD, we antagonized BAFF by prophylactic or therapeutic administration of a soluble fusion protein of the BAFF-receptor, BAFFR-Fc, in mice exposed to air or CS for 24 weeks and evaluated several hallmarks of COPD and polarization of lung macrophages. MEASUREMENTS AND MAIN RESULTS: BAFF expression was significantly increased in lungs of patients with COPD and CS-exposed mice. BAFF staining in lymphoid follicles was observed around B cells, CD4(+) cells, dendritic cells, follicular dendritic cells, and fibroblastic reticular cells. Prophylactic and therapeutic administration of BAFFR-Fc in mice reduced pulmonary B-cell numbers and prevented CS-induced formation of lymphoid follicles and increases in immunoglobulin levels. Interestingly, prophylactic BAFFR-Fc administration significantly attenuated pulmonary inflammation and destruction of alveolar walls. Moreover, antagonizing BAFF altered the phenotype of alveolar and interstitial macrophages. CONCLUSIONS: BAFF is significantly increased in lungs of patients with COPD and is present around both immune and stromal cells within lymphoid follicles. Antagonizing BAFF in CS-exposed mice attenuates pulmonary inflammation and alveolar destruction.

Chronic obstructive pulmonary disease and sudden cardiac death: the Rotterdam study.

AIMS: Both sudden cardiac death (SCD) and chronic obstructive pulmonary disease (COPD) are common conditions in the elderly. Previous studies have identified an association between COPD and cardiovascular disease, and with SCD in specific patient groups. Our aim was to investigate whether there is an association between COPD and SCD in the general population. METHODS AND RESULTS: The Rotterdam study is a population-based cohort study among 14 926 subjects aged 45 years and older with up to 24 years of follow-up. Analyses were performed with a (time dependent) Cox proportional hazard model adjusted for age, sex, and smoking. Of the 13 471 persons included in the analysis; 1615 had a diagnosis of COPD and there were 551 cases of SCD. Chronic obstructive pulmonary disease was associated with an increased risk of SCD (age- and sex-adjusted hazard ratio, HR, 1.34, 95% CI 1.06-1.70). The risk particularly increased in the period 2000 days (5.48 years) after the diagnosis of COPD (age- and sex-adjusted HR 2.12, 95% CI 1.60-2.82) and increased further to a more than three-fold higher risk in COPD subjects with frequent exacerbations during this period (age- and sex-adjusted HR 3.58, 95% CI 2.35-5.44). Analyses restricted to persons without prevalent myocardial infarction or heart failure yielded similar results. CONCLUSION: Chronic obstructive pulmonary disease is associated with an increased risk for SCD. The risk especially increases in persons with frequent exacerbations 5 years after the diagnosis of COPD. This risk indicator could provide new directions for better-targeted actions to prevent SCD.

Transforming growth factor-ß superfamily in obstructive lung diseases. more suspects than TGF-ß alone.

Asthma and chronic obstructive pulmonary disease are respiratory disorders and a major global health problem with increasing incidence and severity. Genes originally associated with lung development could be relevant in the pathogenesis of chronic obstructive pulmonary disease/asthma, owing to either an early-life origin of adult complex diseases or their dysregulation in adulthood upon exposure to environmental stressors (e.g., smoking). The transforming growth factor (TGF)-ß superfamily is conserved through evolution and is involved in a range of biological processes, both during development and in adult tissue homeostasis. TGF-ß1 has emerged as an important regulator of lung and immune system development. However, considerable evidence has been presented for a role of many of the other ligands of the TGF-ß superfamily in lung pathology, including activins, bone morphogenetic proteins, and growth differentiation factors. In this review, we summarize the current knowledge on the mechanisms by which activin, bone morphogenetic protein, and growth differentiation factor signaling contribute to the pathogenesis of obstructive airway diseases.

Gait patterns in COPD: the Rotterdam Study.

Gait disturbances in patients with chronic obstructive pulmonary disease (COPD) may lead to disability and falls. As studies assessing gait kinematics in COPD are sparse, we investigated associations of COPD with various gait domains and explored a potential link with falling. Gait was measured within the prospective, population-based Rotterdam Study (age ≥55 years) using an electronic walkway and summarised into seven gait domains: Rhythm, Variability, Phases, Pace, Tandem, Turning and Base of Support. Rhythm is a temporal gait aspect that includes cadence and reflects how quickly steps are taken. Persons with COPD (n=196) exhibited worse Rhythm (-0.21 SD, 95% CI -0.36- -0.06 SD) compared with persons with normal lung function (n=898), independent of age, sex, height, education, smoking or analgesic use, especially when dyspnoea and severe airflow limitation or frequent exacerbations (Global Initiative for Chronic Obstructive Lung Disease group D: -0.83 SD, 95% CI -1.25- -0.41 SD) were present. A lower forced expiratory volume in 1 s was associated with worse Rhythm and Pace, including lower cadence and gait velocity, respectively. Importantly, fallers with COPD had significantly worse Rhythm than nonfallers with COPD. This study demonstrates that persons with COPD exhibit worse Rhythm, especially fallers with COPD. The degree of Rhythm deterioration was associated with the degree of airflow limitation, symptoms and frequency of exacerbations.

Is there still hope for single therapies: how do we set up experimental systems to efficiently test combination therapies?

Severe asthma, chronic obstructive pulmonary disease (COPD) and idiopathic pulmonary fibrosis (IPF) are chronic lung diseases with a clear need for development of new and more efficient therapy. In preclinical research, the mouse model has been instrumental in advancing our knowledge of the biology and immunology. However, it has been proven rather difficult and time consuming to develop new treatments that can impact on the clinical course of these diseases. Many challenges need to be overcome for upgrading the quality of currently available experimental disease models in order to enhance the translation rate of basic research to clinical practice. Establishment of transgenic mouse overexpressing disease-causing genes may provide tools to discover new pathological pathways and to evaluate the possibility of molecular targeted therapy in chronic lung diseases. Personalized medicine, if developed, might be the solution for 'disease heterogeneity' and for improving clinical outcome.

Role of activin-A in cigarette smoke-induced inflammation and COPD.

Activin-A is a pleiotropic cytokine belonging to the transforming growth factor-ß superfamily and has been implicated in asthma and pulmonary fibrosis. However, the role of activin-A and its endogenous inhibitor, follistatin, in the pathogenesis of chronic obstructive pulmonary disease (COPD) is unknown. We first quantified activin-A and follistatin in the lungs of air- or cigarette smoke-exposed mice and in the lungs of patients with COPD by immunohistochemistry, ELISA and quantitative real-time PCR. We subsequently studied the effect of cigarette smoke on primary human bronchial epithelial cells in vitro. Next, activin-A signalling was antagonised in vivo by administration of follistatin in mice exposed to air or cigarette smoke for 4 weeks. Protein levels of activin-A were increased in the airway epithelium of patients with COPD compared with never-smokers and smokers. Cigarette smoke-exposed human bronchial epithelial cells expressed higher levels of activin-A and lower levels of follistatin. Both mRNA and protein levels of activin-A were increased in the lungs of cigarette smoke-exposed mice, whereas follistatin levels were reduced upon cigarette smoke exposure. Importantly, administration of follistatin attenuated the cigarette smoke-induced increase of inflammatory cells and mediators in the bronchoalveolar lavage fluid in mice. These results suggest that an imbalance between activin-A and follistatin contributes to the pathogenesis of cigarette smoke-induced inflammation and COPD.

Investigation of 5-HT4 receptors in bronchial hyperresponsiveness in cigarette smoke-exposed mice.

BACKGROUND: Chronic obstructive pulmonary disease (COPD) arises from an interaction between genetic host factors and environmental exposures (mainly cigarette smoke (CS)). Genome Wide Association studies have demonstrated that genetic variations in the gene encoding 5-hydroxytryptamine 4 receptors (5-HT(4)R), HTR4, were associated with measures of airway obstruction and with COPD. We hypothesised that 5-HT(4) receptors, in addition to 5-HT2AR and muscarinic receptors, contribute to the pathogenesis of COPD by facilitating cholinergic bronchoconstriction. METHODS: The levels of pulmonary 5-HT(4)R mRNA were measured in CS-exposed mice by qRT-PCR. We investigated the effect of CS exposure on bronchial hyperresponsiveness (BHR) to 5-HT and evaluated the contribution of 5-HT2AR, muscarinic receptors and 5-HT(4)R in the response to 5-HT by using the corresponding antagonists and 5-HT(4)R knockout (KO) mice. RESULTS: The 5-HT(4)R mRNA levels were significantly elevated upon acute (3 days), subacute (4 weeks) and chronic (24 weeks) CS exposure. Both acute and subacute CS exposure significantly increased BHR to 5-HT. Antagonism of 5-HT2AR abolished the CS-induced BHR to 5-HT, and antagonism of muscarinic receptors significantly reduced the response to 5-HT. However, pre-treatment with GR113808, a specific 5-HT(4)R antagonist, did not alter the response to 5-HT in CS-exposed mice. Accordingly, the CS-induced BHR to 5-HT was not different between wild-type and 5-HT(4)R KO mice. CONCLUSION: CS increased the levels of 5-HT(4)R mRNA in the lungs, concomitantly with bronchial responsiveness to 5-HT. Our in vivo data using pharmacologic and genetic approaches suggest that 5-HT(4) receptors are not involved in the BHR to 5-HT in CS-exposed mice.