Respiratory Research - Latest Articles

Anxiety is associated with diminished exercise performance and quality of life in severe emphysema: a cross-sectional study

Nicholas Giardino — 2010-03-09T00:00:00Z

Background: Anxiety in patients with chronic obstructive pulmonary disease (COPD) is associated with self-reported disability. The purpose of this study is to determine whether there is an association between anxiety and functional measures, quality of life and dyspnea. Methods: Data from 1828 patients with moderate to severe emphysema enrolled in the National Emphysema Treatment Trial (NETT), collected prior to rehabilitation and randomization, were used in linear regression models to test the association between anxiety symptoms, measured by the Spielberger State Trait Anxiety Inventory (STAI) and: (a) six-minute walk distance test (6MWD), (b) cycle ergometry peak workload, (c) St. Georges Respiratory Questionnaire (SRGQ), and (d) UCSD Shortness of Breath Questionnaire (SOBQ), after controlling for potential confounders including age, gender, FEV1 (% predicted), DLCO (% predicted), and the Beck Depression Inventory (BDI). Results: Anxiety was significantly associated with worse functional capacity [6MWD (B = -0.944, p < .001), ergometry peak workload (B = -.087, p =.04)], quality of life (B = .172, p < .001) and shortness of breath (B = .180, p < .001). Regression coefficients show that a 10 point increase in anxiety score is associated with a mean decrease in 6MWD of 9 meters, a 1 Watt decrease in peak exercise workload, and an increase of almost 2 points on both the SGRQ and SOBQ. Conclusion: In clinically stable patients with moderate to severe emphysema, anxiety is associated with worse exercise performance, quality of life and shortness of breath, after accounting for the influence of demographic and physiologic factors known to affect these outcomes.Trail Registration: ClinicalTrials.gov NCT00000606

Elevation of IL-6 in the allergic asthmatic airway is independent of inflammation but associates with loss of central airway function

Wendy Neveu — 2010-03-08T00:00:00Z

Background: Asthma is a chronic inflammatory disease of the airway that is characterized by a Th2-type of immune response with increasing evidence for involvement of Th17 cells. The role of IL-6 in promoting effector T cell subsets suggest that IL-6 may play a functional role in asthma. Classically IL-6 has been viewed as an inflammatory marker, along with TNFalpha and IL-1beta, rather than as regulatory cytokine.ObjectiveTo investigate the potential relationship between IL-6 and other proinflammatory cytokines, Th2/Th17 cytokines and lung function in allergic asthma, and thus evaluate the potential role of IL-6 in this disease. Methods: Cytokine levels in induced sputum and lung function were measured in 16 healthy control and 18 mild-moderate allergic asthmatic subjects. Results: The levels of the proinflammatory biomarkers TNFalpha and IL-1beta were not different between the control and asthmatic group. In contrast, IL-6 levels were specifically elevated in asthmatic subjects compared with healthy controls (p<0.01). Hierarchical regression analysis in the total study cohort indicates that the relationship between asthma and lung function could be mediated by IL-6. Among Th2 cytokines only IL-13 (p<0.05) was also elevated in the asthmatic group, and positively correlated with IL-6 levels (rS=0.53, p<0.05). Conclusions: In mild-moderate asthma, IL-6 dissociates from other proinflammatory biomarkers, but correlates with IL-13 levels. Furthermore, IL-6 may contribute to impaired lung function in allergic asthma.

Mechanical ventilation modulates TLR4 and IRAK-3 in a non-infectious, ventilator-induced lung injury model

Jesus Villar — 2010-03-03T00:00:00Z

Background: Previous experimental studies have shown that injurious mechanical ventilation has a direct effect on pulmonary and systemic immune responses. How these responses are propagated or attenuated is a matter of speculation. The goal of this study was to determine the contribution of mechanical ventilation in the regulation of Toll-like receptor (TLR) signaling and interleukin-1 receptor associated kinase-3 (IRAK-3) during experimental ventilator-induced lung injury. Methods: Prospective, randomized, controlled animal study using male, healthy adults Sprague-Dawley rats weighing 300-350 g. Animals were anesthetized and randomized to spontaneous breathing and to two different mechanical ventilation strategies for 4 hours: high tidal volume (VT) (20 ml/kg) and low VT (6 ml/kg). Histological evaluation, TLR2, TLR4, IRAK3 gene expression, IRAK-3 protein levels, inhibitory kappa B alpha (I kappa B alpha), tumor necrosis factor-alpha (TNF-alpha) and interleukin-6 (IL6) gene expression in the lungs and TNF-alpha and IL-6 protein serum concentrations were analyzed. Results: High VT mechanical ventilation was associated with a significant increase of TLR4 but not TLR2, a significant decrease of IRAK3 lung gene expression and protein levels, a significant decrease of I kappa B alpha, and a higher lung expression and serum concentrations of pro-inflammatory cytokines. Conclusions: The current study supports an interaction between TLR4 and IRAK-3 signaling pathway for the over-expression and release of pro-inflammatory cytokines during ventilator-induced lung injury. Our study also suggests that injurious mechanical ventilation may elicit an immune response that is similar to that observed during infections.

The inhaled phosphodiesterase 4 inhibitor GSK256066 reduces allergen challenge responses in asthma

Dave Singh — 2010-03-01T00:00:00Z

GSK256066 is a selective phosphodiesterase 4 inhibitor that can be given by inhalation, minimising the potential for side effects. We evaluated the effects of GSK256066 on airway responses to allergen challenge in mild asthmatics. Methods: In a randomised, double blind, cross-over study, 24 steroid naive atopic asthmatics with both early (EAR) and late (LAR) responses to inhaled allergen received inhaled GSK256066 87.5mcg once per day and placebo for 7 days, followed by allergen challenge. Methacholine reactivity was measured 24h post-allergen. Plasma pharmacokinetics were measured. The primary endpoint was the effect on LAR. Results: GSK256066 significantly reduced the LAR, attenuating the fall in minimum and weighted mean FEV1 by 26.2% (p=0.007) and 34.3% (p=0.005) respectively compared to placebo. GSK256066 significantly reduced the EAR, inhibiting the fall in minimum and weighted mean FEV1 by 40.9% (p=0.014) and 57.2% (p=0.014) respectively compared to placebo. There was no effect on pre-allergen FEV1 or methacholine reactivity post allergen. GSK256066 was well tolerated, with low systemic exposure; plasma levels were not measurable after 4 hours in the majority of subjects. Conclusions: GSK256066 demonstrated a protective effect on the EAR and LAR. This is the first inhaled PDE4 inhibitor to show therapeutic potential in asthma.This study is registered on clinicaltrials.gov NCT00380354

Different HLA-DRB1 allele distributions in distinct clinical subgroups of sarcoidosis patients

Johan Grunewald — 2010-02-26T00:00:00Z

Background: A strong genetic influence by the MHC class II region has been reported in sarcoidosis, however in many studies with different results. This may possibly be caused by actual differences between distinct ethnic groups, too small sample sizes, or because of lack of accurate clinical subgrouping.Subjects and methods. In this study we HLA typed a large patient population (n=754) recruited from one single centre. Patients were sub-grouped into those with Lofgren's syndrome (LS) (n=302) and those without (non-Lofgren's) (n=452), and the majority of them were clinically classified into those with recovery within two years (resolving) and those with signs of disease for more than two years (non-resolving). PCR was used for determination of HLA-DRB1 alleles. Swedish healthy blood donors (n=1366) served as controls. Results: There was a dramatic difference in the distribution of HLA alleles in LS compared to non-LS patients (p=4x10-36). Most notably, DRB1*01, DRB1*03 and DRB1*14, clearly differed in LS and non-LS patients. In relation to disease course, DRB1*07, DRB1*14 and DRB1*15 generally associated with, while DRB1*01 and DRB1*03 protected against, a non-resolving disease. Interestingly, the clinical influence of DRB1*03 (good prognosis) dominated over that of DRB1*15 (bad prognosis). Conclusions: We found several significant differences between LS and non-LS patients and we therefore suggest that genetic association studies in sarcoidosis should include a careful clinical characterisation and sub-grouping of patients, in order to reveal true genetic associations. This may be particularly accurate to do in the heterogeneous non-LS group of patients.

Transcriptional profiling of the acute pulmonary inflammatory response induced by LPS: role of neutrophils

Nejla Gungor — 2010-02-25T00:00:00Z

Background: Lung cancer often develops in association with chronic pulmonary inflammatory diseases with an influx of neutrophils. More detailed information on inflammatory pathways and the role of neutrophils herein is a prerequisite for understanding the mechanism of inflammation associated cancer. Methods: In the present study, we used microarrays in order to obtain a global view of the transcriptional responses of the lung to LPS in mice, which mimics an acute lung inflammation. To investigate the influence of neutrophils in this process, we depleted mice from circulating neutrophils by treatment with anti-PMN antibodies prior to LPS exposure. Results: A total of 514 genes was greater than 1.5-fold differentially expressed in the LPS induced lung inflammation model. 394 of the 514 were up regulated genes mostly involved in cell cycle and immune/inflammation related processes, such as cytokine/chemokine activity and signalling. Down regulated genes represented nonimmune processes, such as development, metabolism and transport. Notably, the number of genes and pathways that were differentially expressed, was reduced when animals were depleted from circulating neutrophils, confirming the central role of neutrophils in the inflammatory response. Furthermore, there was a significant correlation between the differentially expressed gene list and the promutagenic DNA lesion M1dG, suggesting that it is the extent of the immune response which drives genetic instability in the inflamed lung. Several genes that were specifically regulated by the presence of activated neutrophils could be identified and these were mostly involved in interferon signalling, oxidative stress response and cell cycle progression. The latter possibly refers to a higher rate of cell turnover in the inflamed lung with neutrophils, suggesting that the neutrophil influx is associated with a higher risk for the accumulation and fixation of mutations. Conclusion: Gene expression profiling identified specific genes and pathways that are related to neutrophilic inflammation and could be associated to cancer development and indicate an active role of neutrophils in mediating the LPS induced inflammatory response in the mouse lung.

MMP-9 gene variants increase the risk for non- atopic asthma in children

Leonardo Pinto — 2010-02-24T00:00:00Z

Background: Atopic and non-atopic wheezing may be caused by different etiologies: while eosinophils are more important in atopic asthmatic wheezers, neutrophils are predominantly found in BAL samples of young children with wheezing. Both neutrophils as well as eosinophils may secrete matrix metalloproteinase 9 (MMP-9). Considering that MMP-9 plays an important role in airway wall thickening and airway inflammation, it may influence the development of obstructive airway phenotypes in children. In the present study we investigated whether genetic variations in MMP-9 influence the development of different forms of childhood asthma. Methods: Genotyping of four HapMap derived tagging SNPs in the MMP-9 gene was performed using MALDI-TOF MS in three cross sectional study populations of German children (age 9-11; N=4,264) phenotyped for asthma and atopic diseases according to ISAAC standard procedures. Effects of single SNPs and haplotypes were studied using SAS 9.1.3 and Haploview. Results: SNP rs2664538 significantly increased the risk for non-atopic wheezing (OR 2.12, 95%CI 1.40-3.21, p<0.001) and non-atopic asthma (OR 1.66, 95%CI 1.12-2.46, p=0.011). Furthermore, the minor allele of rs3918241 may be associated with decreased expiratory flow measurements in non-atopic children. No significant effects on the development of atopy or total serum IgE levels were observed. Conclusions: Our results have shown that homozygocity for MMP-9 variants increase the risk to develop non-atopic forms of asthma and wheezing, which may be explained by a functional role of MMP-9 in airway remodeling. These results suggest that different wheezing disorders in childhood are affected differently by genetic alterations.

Inhaled salmeterol and/or fluticasone alters structure/function in a murine model of allergic airways disease

Erik Riesenfeld — 2010-02-24T00:00:00Z

Background: The relationship between airway structural changes (remodeling) and airways hyperresponsiveness (AHR) is unclear. Asthma guidelines suggest treating persistent asthma with inhaled corticosteroids and long acting beta-agonists (LABA). We examined the link between physiological function and structural changes following treatment fluticasone and salmeterol separately or in combination in a mouse model of allergic asthma. Methods: BALB/c mice were sensitized to intraperitoneal ovalbumin (OVA) followed by six daily inhalation exposures. Treatments included 9 daily nebulized administrations of fluticasone alone (6mg/ml), salmeterol (3mg/ml), or the combination fluticasone and salmeterol. Lung impedance was measured following methacholine inhalation challenge. Airway inflammation, epithelial injury, mucus containing cells, and collagen content were assessed 48 hours after OVA challenge. Lungs were imaged using micro-CT.Results and DiscussionTreatment of allergic airways disease with fluticasone alone or in combination with salmeterol reduced AHR to approximately naive levels while salmeterol alone increased elastance by 39% compared to control. Fluticasone alone and fluticasone in combination with salmeterol both reduced inflammation to near naive levels. Mucin containing cells were also reduced with fluticasone and fluticasone in combination with salmeterol. Conclusions: Fluticasone alone and in combination with salmeterol reduces airway inflammation and remodeling, but salmeterol alone worsens AHR: and these functional changes are consistent with the concomitant changes in mucus metaplasia.

Effects of PPARgamma ligands on TGF-beta1-induced epithelial-mesenchymal transition in alveolar epithelial cells

Xiahui Tan — 2010-02-23T00:00:00Z

Background: Transforming growth factor beta1 (TGF-beta1)-mediated epithelial mesenchymal transition (EMT) of alveolar epithelial cells (AEC) may contribute to lung fibrosis. Since PPARgamma ligands have been shown to inhibit fibroblast activation by TGF-beta1, we assessed the ability of the thiazolidinediones rosiglitazone (RGZ) and ciglitazone (CGZ) to regulate TGF-beta1-mediated EMT of A549 cells, assessing changes in cell morphology, and expression of cell adhesion molecules E-cadherin (E-cad, epithelial cell marker) and N-cadherin (N-cad, mesenchymal cell marker), and collagen 1alpha1 (COL1A1), CTGF and MMP-2 mRNA. Methods: Serum-deprived A549 cells (human AEC cell line) were pre-incubated with RGZ and CGZ (1 - 30 uM) in the absence or presence of the PPARgamma antagonist GW9662 (10 uM) before TGFbeta-1 (0.075-7.5 ng/ml) treatment for up to 72 hrs. Changes in E-cad, N-cad and phosphorylated Smad2 and Smad3 levels were analysed by Western blot, and changes in mRNA levels including COL1A1 assessed by RT-PCR. Results: TGFbeta-1 (2.5 ng/ml)-induced reductions in E-cad expression were associated with a loss of epithelial morphology and cell-cell contact. Concomitant increases in N-cad, MMP-2, CTGF and COL1A1 were evident in predominantly elongated fibroblast-like cells. Neither RGZ nor CGZ prevented TGFbeta-1-induced changes in cell morphology, and PPARgamma-dependent inhibitory effects of both ligands on changes in E-cad were only evident at submaximal TGF-beta1 (0.25 ng/ml). RGZ inhibited the marked elevation of N-cad and COL1A1 with greater potency than CGZ, with effects on COL1A1 prevented by GW9662. Phosphorylation of Smad2 and Smad3 by TGF-beta1 was not inhibited by RGZ or CGZ. Conclusions: RGZ and CGZ inhibited profibrotic changes in TGF-beta1-stimulated A549 cells independently of inhibition of Smad phosphorylation. Their inhibitory effects on changes in collagen I and E-cad, but not N-cad or CTGF, appeared to be PPARgamma-dependent. Further studies are required to unravel additional mechanisms of inhibition of TGF-beta1 signalling by thiazolidinediones and their implications for the contribution of EMT to lung fibrosis.

Respiratory syncytial virus infection reduces lung inflammation and fibrosis in mice exposed to vanadium pentoxide

Elizabeth Turpin — 2010-02-22T00:00:00Z

Background: Vanadium pentoxide (V2O5) exposure is a cause of occupational bronchitis and airway fibrosis. Respiratory syncytial virus (RSV) is a ubiquitous pathogen that causes airway inflammation. It is unknown whether individuals with pre-existing respiratory viral infection are susceptible to V2O5-induced bronchitis. We hypothesized that respiratory viral infection will exacerbate vanadium-induced lung fibrosis. Methods: In this study we investigated the effect of RSV pre- or post-exposure to V2O5 in male AKR mice. Mice were pre-exposed by intranasal aspiration to RSV or media vehicle prior to intranasal aspiration of V2O5 or saline vehicle at day 1 or day 7. A parallel group of mice were treated first with V2O5 or saline vehicle at day 1 and day 7 then postexposed to RSV or media vehicle at day 8. Results: V2O5-induced airway inflammation and fibrosis were decreased by RSV pre- or post-exposure. Real time quantitative RT-PCR showed that V2O5 significantly increased lung mRNAs encoding pro-fibrogenic growth factors (TGF-beta1, CTGF, PDGF-C) and collagen (Col1A2), but also increased mRNAs encoding anti-fibrogenic type I interferons(IFN-alpha, -beta) and IFN-inducible chemokines (CXCL9 and CXCL10). RSV pre- or postexposure caused a significantly reduced mRNAs of pro-fibrogenic growth factors and collagen, yet reduced RNA levels of anti-fibrogenic interferons and CXC chemokines. Conclusions: Collectively these data suggest that RSV infection reduces the severity of V2O5-induced fibrosis by suppressing growth factors and collagen genes. However, RSV suppression of V2O5-induced IFNs and IFN-inducible chemokines suggests that viral infection also suppresses the innate immune response that normally serves to resolve V2O5-induced fibrosis.