Effects of Phosphodiesterase 4 Inhibition on Alveolarization and Hyperoxia Toxicity in Newborn Rats

International audienceBACKGROUND: Prolonged neonatal exposure to hyperoxia is associated with high mortality, leukocyte influx in airspaces, and impaired alveolarization. Inhibitors of type 4 phosphodiesterases are potent anti-inflammatory drugs now proposed for lung disorders. The current study was undertaken to determine the effects of the prototypal phosphodiesterase-4 inhibitor rolipram on alveolar development and on hyperoxia-induced lung injury. METHODOLOGY/FINDINGS: Rat pups were placed under hyperoxia (FiO2>95%) or room air from birth, and received rolipram or its diluent daily until sacrifice. Mortality rate, weight gain and parameters of lung morphometry were recorded on day 10. Differential cell count and cytokine levels in bronchoalveolar lavage and cytokine mRNA levels in whole lung were recorded on day 6. Rolipram diminished weight gain either under air or hyperoxia. Hyperoxia induced huge mortality rate reaching 70% at day 10, which was prevented by rolipram. Leukocyte influx in bronchoalveolar lavage under hyperoxia was significantly diminished by rolipram. Hyperoxia increased transcript and protein levels of IL-6, MCP1, and osteopontin; rolipram inhibited the increase of these proteins. Alveolarization was impaired by hyperoxia and was not restored by rolipram. Under room air, rolipram-treated pups had significant decrease of Radial Alveolar Count. CONCLUSIONS: Although inhibition of phosphodiesterases 4 prevented mortality and lung inflammation induced by hyperoxia, it had no effect on alveolarization impairment, which might be accounted for by the aggressiveness of the model. The less complex structure of immature lungs of rolipram-treated pups as compared with diluent-treated pups under room air may be explained by the profound effect of PDE4 inhibition on weight gain that interfered with normal alveolarization

Pentraxin 3 (PTX3) Expression in Allergic Asthmatic Airways: Role in Airway Smooth Muscle Migration and Chemokine Production

Pentraxin 3 (PTX3) is a soluble pattern recognition receptor with non-redundant functions in inflammation and innate immunity. PTX3 is produced by immune and structural cells. However, very little is known about the expression of PTX3 and its role in allergic asthma.We sought to determine the PTX3 expression in asthmatic airways and its function in human airway smooth muscle cells (HASMC). In vivo PTX3 expression in bronchial biopsies of mild, moderate and severe asthmatics was analyzed by immunohistochemistry. PTX3 mRNA and protein were measured by real-time RT-PCR and ELISA, respectively. Proliferation and migration were examined using (3)H-thymidine incorporation, cell count and Boyden chamber assays.PTX3 immunoreactivity was increased in bronchial tissues of allergic asthmatics compared to healthy controls, and mainly localized in the smooth muscle bundle. PTX3 protein was expressed constitutively by HASMC and was significantly up-regulated by TNF, and IL-1β but not by Th2 (IL-4, IL-9, IL-13), Th1 (IFN-γ), or Th-17 (IL-17) cytokines. In vitro, HASMC released significantly higher levels of PTX3 at the baseline and upon TNF stimulation compared to airway epithelial cells (EC). Moreover, PTX3 induced CCL11/eotaxin-1 release whilst inhibited the fibroblast growth factor-2 (FGF-2)-driven HASMC chemotactic activity.Our data provide the first evidence that PTX3 expression is increased in asthmatic airways. HASMC can both produce and respond to PTX3. PTX3 is a potent inhibitor of HASMC migration induced by FGF-2 and can upregulate CCL11/eotaxin-1 release. These results raise the possibility that PTX3 may play a dual role in allergic asthma

Mevalonate Cascade Regulation of Airway Mesenchymal Cell Autophagy and Apoptosis: A Dual Role for p53

Statins inhibit the proximal steps of cholesterol biosynthesis, and are linked to health benefits in various conditions, including cancer and lung disease. We have previously investigated apoptotic pathways triggered by statins in airway mesenchymal cells, and identified reduced prenylation of small GTPases as a primary effector mechanism leading to p53-mediated cell death. Here, we extend our studies of statin-induced cell death by assessing endpoints of both apoptosis and autophagy, and investigating their interplay and coincident regulation. Using primary cultured human airway smooth muscle (HASM) and human airway fibroblasts (HAF), autophagy, and autophagosome formation and flux were assessed by transmission electron microscopy, cytochemistry (lysosome number and co-localization with LC3) and immunoblotting (LC3 lipidation and Atg12-5 complex formation). Chemical inhibition of autophagy increased simvastatin-induced caspase activation and cell death. Similarly, Atg5 silencing with shRNA, thus preventing Atg5-12 complex formation, increased pro-apoptotic effects of simvastatin. Simvastatin concomitantly increased p53-dependent expression of p53 up-regulated modulator of apoptosis (PUMA), NOXA, and damage-regulated autophagy modulator (DRAM). Notably both mevalonate cascade inhibition-induced autophagy and apoptosis were p53 dependent: simvastatin increased nuclear p53 accumulation, and both cyclic pifithrin-α and p53 shRNAi partially inhibited NOXA, PUMA expression and caspase-3/7 cleavage (apoptosis) and DRAM expression, Atg5-12 complex formation, LC3 lipidation, and autophagosome formation (autophagy). Furthermore, the autophagy response is induced rapidly, significantly delaying apoptosis, suggesting the existence of a temporally coordinated p53 regulation network. These findings are relevant for the development of statin-based therapeutic approaches in obstructive airway disease

Endogenous laminin is required for human airway smooth muscle cell maturation

BACKGROUND: Airway smooth muscle (ASM) contraction underlies acute bronchospasm in asthma. ASM cells can switch between a synthetic-proliferative phenotype and a contractile phenotype. While the effects of extracellular matrix (ECM) components on modulation of ASM cells to a synthetic phenotype have been reported, the role of ECM components on maturation of ASM cells to a contractile phenotype in adult lung is unclear. As both changes in ECM components and accumulation of contractile ASM are features of airway wall remodelling in asthma, we examined the role of the ECM protein, laminin, in the maturation of contractile phenotype in human ASM cells. METHODS: Human ASM cells were made senescence-resistant by stable expression of human telomerase reverse transcriptase. Maturation to a contractile phenotype was induced by 7-day serum deprivation, as assessed by immunoblotting for desmin and calponin. The role of laminin on ASM maturation was investigated by comparing the effects of exogenous laminin coated on culture plates, and of soluble laminin peptide competitors. Endogenous expression of laminin chains during ASM maturation was also measured. RESULTS: Myocyte binding to endogenously expressed laminin was required for ASM phenotype maturation, as laminin competing peptides (YIGSR or GRGDSP) significantly reduced desmin and calponin protein accumulation that otherwise occurs with prolonged serum deprivation. Coating of plastic cell culture dishes with different purified laminin preparations was not sufficient to further promote accumulation of desmin or calponin during 7-day serum deprivation. Expression of α2, β1 and γ1 laminin chains by ASM cells was specifically up-regulated during myocyte maturation, suggesting a key role for laminin-2 in the development of the contractile phenotype. CONCLUSION: While earlier reports suggest exogenously applied laminin slows the spontaneous modulation of ASM to a synthetic phenotype, we show for the first time that endogenously expressed laminin is required for ASM maturation to the contractile phenotype. As endogenously expressed laminin chains α2, β1 and γ1 are uniquely increased during myocyte maturation, these laminin chains may be key in this process. Thus, human ASM maturation appears to involve regulated endogenous expression of a select set of laminin chains that are essential for accumulation of contractile phenotype myocytes

Effect of a Community-Wide Asthma Intervention on Appropriate Use of Inhaled Corticosteroids

Individuals with asthma living in the inner city experience increased asthma morbidity and mortality compared to the US average. The Controlling Asthma in America’s Cities Project’s Chicago site used a multifaceted approach to improve asthma care. The diverse scope of this project’s interventions necessitated the use of novel methods to assess the effect of these interventions on the entire study area. Asthma-related medication-dispensing data were obtained from a large pharmacy chain for prescriptions filled in calendar years 2004–2006 for all individuals aged 5–17 years living in Chicago who filled at least four asthma-related medications within a 12-month period. Inhaled corticosteroid (ICS) use was considered inadequate if an individual had four or more dispensings of a short-acting beta-agonist without at least four dispensings of an ICS agent. Logistic regression was used to compare adequate ICS use in individuals within the intervention area with ICS use in the remainder of the city, after controlling for gender, insurance status, race, and poverty. A significant difference in adequate ICS use was found in years 2 (2005) and 3 (2006) of the project for individuals aged 5–9 in the intervention area (odds ratios for adequate ICS use—year 2, 1.26; CI, 1.04–1.53, p = 0.04; year 3, 1.30; CI, 1.08–1.55, p = 0.008) compared to individuals aged 5–9 in the remainder of the city. There was no similar significant difference in the 10–17 age group. These findings suggest an effect of a large multifaceted asthma intervention in improving medication use in the targeted age group. This methodology might also prove useful in the future for assessing the effect of similar interventions

Inhaled corticosteroids for asthma: impact of practice level device switching on asthma control

Background As more inhaled corticosteroid (ICS) devices become available, there may be pressure for health-care providers to switch patients with asthma to cheaper inhaler devices. Our objective was to evaluate impact on asthma control of inhaler device switching without an accompanying consultation in general practice. Methods This 2-year retrospective matched cohort study used the UK General Practice Research Database to identify practices where ICS devices were changed without a consultation for ≥5 patients within 3 months. Patients 6–65 years of age from these practices whose ICS device was switched were individually matched with patients using the same ICS device who were not switched. Asthma control over 12 months after the switch was assessed using a composite measure including short-acting β-agonist and oral corticosteroid use, hospitalizations, and subsequent changes to therapy. Results A total of 824 patients from 55 practices had a device switch and could be matched. Over half (53%) of device switches were from dry powder to metered-dose inhalers. Fewer patients in switched than matched cohort experienced successful treatment based on the composite measure (20% vs. 34%) and more experienced unsuccessful treatment (51% vs. 38%). After adjusting for possible baseline confounding factors, the odds ratio for treatment success in the switched cohort compared with controls was 0.29 (95% confidence interval [CI], 0.19 to 0.44; p < 0.001) and for unsuccessful treatment was 1.92 (95% CI, 1.47 to 2.56; p < 0.001). Conclusion Switching ICS devices without a consultation was associated with worsened asthma control and is therefore inadvisable

Respiratory and bronchitic symptoms predict intention to quit smoking among current smokers with and at risk for COPD

RATIONALE: Smoking cessation is the most important intervention for patients with chronic obstructive pulmonary disease (COPD). What leads smokers with COPD to quit smoking remains unknown. OBJECTIVES: We sought to examine the association between respiratory symptoms and other markers of COPD severity with intention to quit smoking among a cohort of patients with probable COPD. METHODS: We conducted a cross-sectional study of subjects with COPD or fixed airflow obstruction clinically diagnosed on the basis of pulmonary function testing. The subjects were identified in the COPD Outcomes-based Network for Clinical Effectiveness and Research Translation multicenter registry. The primary outcome was the intention to quit smoking within the next 30 days (yes or no), which was examined using model building with multivariable logistic regression, clustered by study site. MEASUREMENTS AND MAIN RESULTS: We identified 338 current smokers with COPD via the registry. Of these subjects, 57.4% (n = 194) had confirmed airflow obstruction based on pulmonary function testing. Nearly one-third (29.2%; n = 99) intended to quit smoking in the next 30 days. In adjusted analyses, compared with subjects without airflow obstruction based on pulmonary function testing, subjects with Global Initiative for Chronic Obstructive Lung Disease stage I/II COPD were more likely to be motivated to quit (odds ratio [OR], 1.85; 95% confidence interval [CI], 1.37-2.49), with no association found for subjects with Global Initiative for Chronic Obstructive Lung Disease stage III/IV disease. Among the entire cohort, frequent phlegm (OR, 2.10; 95% CI, 1.22-3.64), cough (OR, 1.74; 95% CI, 1.01-2.99), wheeze (OR, 1.73; 95% CI, 1.09-3.18), and higher modified Medical Research Council dyspnea score (OR, 1.26 per point; 95% CI, 1.13-1.41) were associated with increased odds of intending to quit smoking. Low self-reported health was associated with decreased odds of intending to quit (OR, 0.75; 95% CI, 0.62-0.92). CONCLUSIONS: Frequent cough, phlegm, wheeze, and shortness of breath were associated with intention to quit smoking in the next 30 days, with a less clear relationship for severity of illness graded by pulmonary function testing and self-rated health. These findings can be used to inform the content of tobacco cessation interventions to provide a more tailored approach for patients with respiratory diseases such as COPD