The balance and distribution of epithelial cell types is required to maintain tissue homeostasis. A hallmark of airway diseases is epithelial remodeling, leading to increased goblet cell numbers and an overproduction of mucus. In the conducting airway, basal cells act as progenitors for both secretory and ciliated cells. To identify mechanisms regulating basal cell fate, we developed a screenable 3D culture system of airway epithelial morphogenesis. We performed a high-throughput screen using a collection of secreted proteins and identified inflammatory cytokines that specifically biased basal cell differentiation toward a goblet cell fate, culminating in enhanced mucus production. We also demonstrate a specific requirement for Notch2 in cytokine-induced goblet cell metaplasia in vitro and in vivo. We conclude that inhibition of Notch2 prevents goblet cell metaplasia induced by a broad range of stimuli and propose Notch2 neutralization as a therapeutic strategy for preventing goblet cell metaplasia in airway diseases.

Rationale: Most airway diseases, including chronic obstructive pulmonary disease (COPD), are associated with excessive coughing. The extent to which this may be a consequence of increased activation of vagal afferents by pathology in the airways (e.g., inflammatory mediators, excessive mucus) or an altered neuronal phenotype is unknown. Understanding whether respiratory diseases are associated with dysfunction of airway sensory nerves has the potential to identify novel therapeutic targets.Objectives: To assess the changes in cough responses to a range of inhaled irritants in COPD and model these in animals to investigate the underlying mechanisms.Methods: Cough responses to inhaled stimuli in patients with COPD, healthy smokers, refractory chronic cough, asthma, and healthy volunteers were assessed and compared with vagus/airway nerve and cough responses in a cigarette smoke (CS) exposure guinea pig model. Measurements and Main Results:Patients with COPD had heightened cough responses to capsaicin but reduced responses to prostaglandin E 2 compared with healthy volunteers. Furthermore, the different patient groups all exhibited different patterns of modulation of cough responses. Consistent with these findings, capsaicin caused a greater number of coughs in CS-exposed guinea pigs than in control animals; similar increased responses were observed in ex vivo vagus nerve and neuron cell bodies in the vagal ganglia. However, responses to prostaglandin E 2 were decreased by CS exposure.Conclusions: CS exposure is capable of inducing responses consistent with phenotypic switching in airway sensory nerves comparable with the cough responses observed in patients with COPD. Moreover, the differing profiles of cough responses support the concept of disease-specific neurophenotypes in airway disease.Clinical trial registered with www.clinicaltrials.gov (NCT 01297790).

BackgroundChronic lung diseases are the third leading cause of death in the United States due in part to an incomplete understanding of pathways that govern the progressive tissue remodeling that occurs in these disorders. Adenosine is elevated in the lungs of animal models and humans with chronic lung disease where it promotes air-space destruction and fibrosis. Adenosine signaling increases the production of the pro-fibrotic cytokine interleukin-6 (IL-6). Based on these observations, we hypothesized that IL-6 signaling contributes to tissue destruction and remodeling in a model of chronic lung disease where adenosine levels are elevated.Methodology/Principal FindingsWe tested this hypothesis by neutralizing or genetically removing IL-6 in adenosine deaminase (ADA)-deficient mice that develop adenosine dependent pulmonary inflammation and remodeling. Results demonstrated that both pharmacologic blockade and genetic removal of IL-6 attenuated pulmonary inflammation, remodeling and fibrosis in this model. The pursuit of mechanisms involved revealed adenosine and IL-6 dependent activation of STAT-3 in airway epithelial cells.Conclusions/SignificanceThese findings demonstrate that adenosine enhances IL-6 signaling pathways to promote aspects of chronic lung disease. This suggests that blocking IL-6 signaling during chronic stages of disease may provide benefit in halting remodeling processes such as fibrosis and air-space destruction.

Asthmatics, unlike healthy subjects, experience bronchoconstriction in response to inhaled adenosine, and extracellular adenosine concentrations are elevated in the bronchoalveolar lavage fluid and exhaled breath condensate of asthmatic subjects. However, little is known about the location and expression of adenosine receptors in asthmatic airways. The aim of the present study was to investigate the distribution of adenosine A 1 receptors in bronchial biopsy specimens from mildly asthmatic steroid-naïve subjects and then compare the degree of expression with that of healthy subjects.Biopsy sections were immunostained using an adenosine A 1 receptor antibody, the selectivity of which was validated in specific experiments. Image analysis was then performed in order to determine differences in immunostaining intensity.Immunostaining of biopsy sections from the asthmatic subjects revealed strong expression of the A 1 receptor, located predominantly in the bronchial epithelium and bronchial smooth muscle. In comparison, very weak immunostaining was observed in biopsy specimens obtained from healthy subjects. Image analysis revealed that the intensity of positive staining of the asthmatic bronchial epithelium and smooth muscle regions was significantly greater than that observed for the healthy epithelium and smooth muscle.In conclusion, the sensitivity of asthmatics to inhaled adenosine coupled with increased adenosine A 1 receptor expression implies that these receptors play a role in the pathophysiology of this disease. KEYWORDS: Adenosine, adenosine A 1 receptor, adenosine A 1 receptor expression, asthma A denosine is a purine nucleoside that is expressed in all cells of the body and involved in a wide range of physiological processes. The effects of adenosine are mediated predominantly through specific cell surface receptors, of which four subtypes (A 1 , A 2A , A 2B and A 3 ) have been described. It is now well recognised that extracellular levels of adenosine markedly increase under metabolically stressful conditions, such as hypoxia and inflammation, and, although an acutely elevated level of extracellular adenosine is considered to mediate anti-inflammatory and protective effects, chronic accumulation has been associated with pathological consequences [1].In asthmatic subjects, it has been demonstrated that adenosine levels in bronchoalveolar lavage fluid and exhaled breath condensate are significantly higher than those occurring in healthy subjects [2,3], and current evidence strongly suggests that they may contribute to the pathophysiology of asthma. For example, it has been recognised since the mid-1980s that inhalation of adenosine 59-monophosphate (AMP; 5'-nucleotidase rapidly hydrolyses AMP to adenosine in the lung) in asthmatic but not healthy subjects results in dose-related bronchoconstriction [4]. This is considered to be mediated predominantly, but not exclusively, by mast cell degranulation via A 2B receptor activation (reviewed in [5]). Furthermore, inhalation of AMP has been shown to i...

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Elderly patients frequently fail to achieve or to retain a competent inhaler technique using a conventional metered dose inhaler. In a prospective, randomised, crossover study of 44 subjects aged 64–94 (mean 78) years, we compared a metered dose inhaler (MDI) with a breath actuated inhaler (BAI) in terms of inhaler technique, ease of teaching and patient acceptability. Patients were stratified according to physical, functional or cognitive impairment before randomisation. Structured tuition was provided at the start of treatments, and technique was graded weekly and retaught if deficient. At the start of the treatment periods satisfactory technique was observed in 14 of 35 patients (six impaired, eight unimpaired) using the MDI and in 14 of 35 patients (three impaired, 11 unimpaired) using the BAI (P = 1.0). At the end of the four‐week treatment periods satisfactory technique was observed in 19 of 30 patients (seven impaired, 12 unimpaired) using the MDI and in 27 patients (11 impaired, 16 unimpaired) using the BAI (P = 0.01). Mean weekly teaching times (minutes) were similar (MDI 7.0, BAI 6.5, P = 0.41) and there was no difference in terms of patient acceptability (P = 0.38). A breath actuated inhaler may be the preferred device for elderly patients as a greater proportion were able to retain satisfactory inhaler technique.

The release of PGE and SRS from mouse resident peritoneal macrophages has been studied after various stimuli. Both substances were released, in most cases, conjointly and were inhibited by drugs in a similar manner. IntroductionMacrophages release large amounts of prostaglandins in response to certain phagocytic stimuli [1] reflecting the high content of arachidonic acid in the phospholipids of their membranes [21. Mouse macrophages exposed to zymosan release a slow reacting substance (SRS) similar to leuko triene C 4 [31. We report the effects of various particulate and soluble stimuli on the release of PGE and SRS from mouse macrophages and the modulation of release by drugs.

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