Aquaporin 5 polymorphisms and rate of lung function decline in chronic obstructive pulmonary disease

Rationale

Aquaporin-5 (AQP5) can cause mucus overproduction and lower lung function. Genetic variants in the AQP5 gene might be associated with rate of lung function decline in chronic obstructive pulmonary disease (COPD).

Methods

Five single nucleotide polymorphisms (SNPs) in AQP5 were genotyped in 429 European American individuals with COPD randomly selected from the NHLBI Lung Health Study. Mean annual decline in FEV₁ % predicted, assessed over five years, was calculated as a linear regression slope, adjusting for potential covariates and stratified by smoking status. Constructs containing the wildtype allele and risk allele of the coding SNP N228K were generated using site-directed mutagenesis, and transfected into HBE-16 (human bronchial epithelial cell line). AQP5 abundance and localization were assessed by immunoblots and confocal immunofluoresence under control, shear stress and cigarette smoke extract (CSE 10%) exposed conditions to test for differential expression or localization.

Results

Among continuous smokers, three of the five SNPs tested showed significant associations (0.02>P>0.004) with rate of lung function decline; no associations were observed among the group of intermittent or former smokers. Haplotype tests revealed multiple association signals (0.012>P>0.0008) consistent with the single-SNP results. In HBE16 cells, shear stress and CSE led to a decrease in AQP5 abundance in the wild-type, but not in the N228K AQP5 plasmid.

Conclusions

Polymorphisms in AQP5 were associated with rate of lung function decline in continuous smokers with COPD. A missense mutation modulates AQP-5 expression in response to cigarette smoke extract and shear stress. These results suggest that AQP5 may be an important candidate gene for COPD.     

Correlating changes in lung function with patient outcomes in chronic obstructive pulmonary disease: a pooled analysis

Background

Relationships between improvements in lung function and other clinical outcomes in chronic obstructive pulmonary disease (COPD) are not documented extensively. We examined whether changes in trough forced expiratory volume in 1 second (FEV₁) are correlated with changes in patient-reported outcomes.

Methods

Pooled data from three indacaterol studies (n = 3313) were analysed. Means and responder rates for outcomes including change from baseline in Transition Dyspnoea Index (TDI), St. George''s Respiratory Questionnaire (SGRQ) scores (at 12, 26 and 52 weeks), and COPD exacerbation frequency (rate/year) were tabulated across categories of ΔFEV₁. Also, generalised linear modelling was performed adjusting for covariates such as baseline severity and inhaled corticosteroid use.

Results

With increasing positive ΔFEV₁, TDI and ΔSGRQ improved at all timepoints, exacerbation rate over the study duration declined (P < 0.001). Individual-level correlations were 0.03-0.18, but cohort-level correlations were 0.79-0.95. At 26 weeks, a 100 ml increase in FEV₁ was associated with improved TDI (0.46 units), ΔSGRQ (1.3-1.9 points) and exacerbation rate (12% decrease). Overall, adjustments for baseline covariates had little impact on the relationship between ΔFEV₁ and outcomes.

Conclusions

These results suggest that larger improvements in FEV₁ are likely to be associated with larger patient-reported benefits across a range of clinical outcomes.

Trial Registration

ClinicalTrials.gov {"type":"clinical-trial","attrs":{"text":"NCT00393458","term_id":"NCT00393458"}}NCT00393458, {"type":"clinical-trial","attrs":{"text":"NCT00463567","term_id":"NCT00463567"}}NCT00463567, and {"type":"clinical-trial","attrs":{"text":"NCT00624286","term_id":"NCT00624286"}}NCT00624286     

Association of glutathione-S-transferase omega haplotypes with susceptibility to chronic obstructive pulmonary disease

Cigarette smoking is the main risk factor for developing the inflammatory lung disease chronic obstructive pulmonary disease (COPD). Differences in susceptibility among smokers have been attributed to a genetic predisposition. A recent publication on the Framingham Heart Study found a strong association of the Asn142Asp SNP in Glutatthione-S-transferase Omega (GSTO) 2 with forced expiratory volume in the first second (FEV₁) and forced vital capacity (FVC). FEV₁ is the main parameter reflecting the degree of airflow limitation in patients with COPD. Therefore the present study was undertaken to investigate whether the Asn142Asp polymorphism in GSTO2 occurs more frequently in patients with COPD than healthy subjects and to replicate the finding that it strongly correlates with FEV₁. Furthermore, the Ala140Asp substitution in GSTO1 was examined. Genotyping was carried out in 195 healthy controls and 355 patients with COPD. The results demonstrate that the Asn142Asp polymorphism in GSTO2 and the GSTO1140Asp/GSTO2142Asp haplotype were associated with increased risk of COPD. However, single-marker and haplotype-based analyses failed to reveal an association between lung function parameters and investigated non-synonymous coding SNPs in the GSTO genes. In conclusion, GSTO2 is a candidate gene for COPD, but is not associated with FEV₁.     

Effects of exercise and beta 2-agonists on lung function in chronic obstructive pulmonary disease.

The effects of inhaled bronchodilators at rest and during exercise were studied in 15 subjects with chronic obstructive pulmonary disease. In a crossover study against placebo, albuterol caused a significant increase in expiratory flow and reduced lung hyperinflation and dyspnea at rest, but this was not associated with differences in symptoms with exercise or any relevant parameter of physical performance. Dynamic hyperinflation occurred during exercise similarly after placebo or albuterol and was associated with a reduction of forced expiratory flows. This, in turn, was correlated with the bronchoconstrictor effect of deep inhalation determined at rest. In a parallel group study, expiratory flow was increased by 3-wk treatment with salmeterol (n = 9) but not with placebo (n = 6). However, in neither group was the response to exercise different from baseline. These results suggest that in chronic obstructive pulmonary disease effective pharmacological bronchodilation at rest may not be predictive of benefits of exercise tolerance. This may be related to the occurrence of airway narrowing during exercise, particularly when a deep inhalation at rest is followed by a decrease in expiratory flow.     

Prediction and course of symptoms and lung function around an exacerbation in chronic obstructive pulmonary disease

Background

Frequent exacerbations induce a high burden to Chronic Obstructive Pulmonary Disease (COPD). We investigated the course of exacerbations in the published COSMIC study that investigated the effects of 1-year withdrawal of fluticasone after a 3-month run-in treatment period with salmeterol/fluticasone in patients with COPD.

Methods

In 373 patients, we evaluated diary cards for symptoms, Peak Expiratory Flow (PEF), and salbutamol use and assessed their course during exacerbations.

Results

There were 492 exacerbations in 224 patients. The level of symptoms of cough, sputum, dyspnea and nocturnal awakening steadily increased from 2 weeks prior to exacerbation, with a sharp rise during the last week. Symptoms of cough, sputum, and dyspnea reverted to baseline values at different rates (after 4, 4, and 7 weeks respectively), whereas symptoms of nocturnal awakening were still increased after eight weeks. The course of symptoms was similar around a first and second exacerbation. Increases in symptoms and salbutamol use and decreases in PEF were associated with a higher risk to develop an exacerbation, but with moderate predictive values, the areas under the receiver operating curves ranging from 0.63 to 0.70.

Conclusions

Exacerbations of COPD are associated with increased symptoms that persist for weeks and the course is very similar between a first and second exacerbation. COPD exacerbations are preceded by increased symptoms and salbutamol use and lower PEF, yet predictive values are too low to warrant daily use in clinical practice.     

DNAH5 is associated with total lung capacity in chronic obstructive pulmonary disease

Background

Chronic obstructive pulmonary disease (COPD) is characterized by expiratory flow limitation, causing air trapping and lung hyperinflation. Hyperinflation leads to reduced exercise tolerance and poor quality of life in COPD patients. Total lung capacity (TLC) is an indicator of hyperinflation particularly in subjects with moderate-to-severe airflow obstruction. The aim of our study was to identify genetic variants associated with TLC in COPD.

Methods

We performed genome-wide association studies (GWASs) in white subjects from three cohorts: the COPDGene Study; the Evaluation of COPD Longitudinally to Identify Predictive Surrogate Endpoints (ECLIPSE); and GenKOLS (Bergen, Norway). All subjects were current or ex-smokers with at least moderate airflow obstruction, defined by a ratio of forced expiratory volume in 1 second to forced vital capacity (FEV₁/FVC) <0.7 and FEV₁ < 80% predicted on post-bronchodilator spirometry. TLC was calculated by using volumetric computed tomography scans at full inspiration (TLC_CT). Genotyping in each cohort was completed, with statistical imputation of additional markers. To find genetic variants associated with TLC_CT, linear regression models were used, with adjustment for age, sex, pack-years of smoking, height, and principal components for genetic ancestry. Results were summarized using fixed-effect meta-analysis.

Results

Analysis of a total of 4,543 COPD subjects identified one genome-wide significant locus on chromosome 5p15.2 (rs114929486, β = 0.42L, P = 4.66 × 10⁻⁸).

Conclusions

In COPD, TLC_CT was associated with a SNP in dynein, axonemal, heavy chain 5 (DNAH5), a gene in which genetic variants can cause primary ciliary dyskinesia. DNAH5 could have an effect on hyperinflation in COPD.

Electronic supplementary material

The online version of this article (doi:10.1186/s12931-014-0097-y) contains supplementary material, which is available to authorized users.     

Dual function inhibitors of relevance to chronic obstructive pulmonary disease

The general strategy and rationale underlying the design of COPD therapeutics that possess protease inhibitory activity and are also capable of releasing a species that attenuates inflammation by inhibiting caspase-1, are described. The synthesis and in vitro biochemical evaluation of a dual function molecule that sequentially inhibits HNE and caspase-1 in a time-dependent manner is reported.     

Regulation of transplanted mesenchymal stem cells by the lung progenitor niche in rats with chronic obstructive pulmonary disease

Background

Stem cell transplantation is a promising method for the treatment of chronic obstructive pulmonary disease (COPD), and mesenchymal stem cells (MSCs) have clinical potential for lung repair/regeneration. However, the rates of engraftment and differentiation are generally low following MSC therapy for lung injury. In previous studies, we constructed a pulmonary surfactant-associated protein A (SPA) suicide gene system, rAAV-SPA-TK, which induced apoptosis in alveolar epithelial type II (AT II) cells and vacated the AT II cell niche. We hypothesized that this system would increase the rates of MSC engraftment and repair in COPD rats.

Methods

The MSC engraftment rate and morphometric changes in lung tissue in vivo were investigated by in situ hybridization, hematoxylin and eosin staining, Masson’s trichrome staining, immunohistochemistry, and real-time PCR. The expression of hypoxia inducible factor (HIF-1α) and stromal cell-derived factor-1 (SDF-1), and relationship between HIF-1α and SDF-1 in a hypoxic cell model were analyzed by real-time PCR, western blotting, and enzyme-linked immunosorbent assay.

Results

rAAV-SPA-TK transfection increased the recruitment of MSCs but induced pulmonary fibrosis in COPD rats. HIF-1α and SDF-1 expression were enhanced after rAAV-SPA-TK transfection. Hypoxia increased the expression of HIF-1α and SDF-1 in the hypoxic cell model, and SDF-1 expression was augmented by HIF-1α under hypoxic conditions.

Conclusions

Vacant AT II cell niches increase the homing and recruitment of MSCs to the lung in COPD rats. MSCs play an important role in lung repair and promote collagen fiber deposition after induction of secondary damage in AT II cells by rAAV-SPA-TK, which involves HIF-1α and SDF-1 signaling.     

Emphysema distribution and annual changes in pulmonary function in male patients with chronic obstructive pulmonary disease

Background

The progression of chronic obstructive pulmonary disease (COPD) considerably varies among patients. Those with emphysema identified by quantitative computed tomography (CT) are associated with the rapid progression assessed by forced expiratory volume in one second (FEV₁). However, whether the rate of the decline in lung function is independently affected by the regional distribution or the severity of emphysema in the whole lung is unclear.

Methods

We followed up 131 male patients with COPD for a median of 3.7 years. We measured wall area percent (WA%) in right apical segmental bronchus, total lung volume, percent low attenuation volume (LAV%), and the standard deviation (SD) of LAV% values from CT images of 10 isovolumetric partitions (SD-LAV) as an index of cranial-caudal emphysema heterogeneity. Annual changes in FEV₁ were then determined using a random coefficient model and relative contribution of baseline clinical parameters, pulmonary function, and CT indexes including LAV%, SD-LAV, and WA% to annual changes in FEV₁ were examined.

Results

The mean (SD) annual change in FEV₁ was −44.4 (10.8) mL. Multivariate random coefficient model showed that higher baseline FEV₁, higher LAV%, current smoking, and lower SD-LAV independently contributed to an excessive decline in FEV₁, whereas ratio of residual volume to total lung capacity, ratio of diffusing capacity to alveolar ventilation, and WA% did not, after adjusting for age, height, weight, and ratio of CT-measured total lung volume to physiologically-measured total lung capacity.

Conclusions

A more homogeneous distribution of emphysema contributed to an accelerated decline in FEV₁ independently of baseline pulmonary function, whole-lung emphysema severity, and smoking status. In addition to whole-lung analysis of emphysema, CT assessment of the cranial-caudal distribution of emphysema might be useful for predicting rapid, progressive disease and for developing a targeted strategy with which to prevent disease progression.     

慢性阻塞性肺疾病患者肠道微生物组成及基因功能分析

探讨慢性阻塞性肺疾病（COPD）患者肠道微生物组成、丰度及差异基因功能变化。

收集我院呼吸科10例确诊COPD患者（COPD组）和10例对照受试者（对照组）粪便样品进行宏基因组高通量测序分析。

PCA分析组间比较发现2组研究对象粪便样品微生物群落差异大,具有可比性。物种组成分析显示：对照组粪便样品中高度富集的菌科主要包括毛螺菌科、理研菌科、韦荣球菌科、优杆菌科、臭杆菌科、氨基酸球菌科、乳杆菌科等,属层面富集的主要包括罗斯菌属、胃瘤球菌属、小杆菌属、真杆菌属、拟杆菌属、粪球菌属、双歧杆菌属等;COPD组粪便样品富集菌群主要包括紫单胞菌科、Selenomonadaceae、巨单胞菌属和韦荣球菌属。物种多样性分析与对照组相比,COPD组多样性更低,差异有统计学意义（W = 87,P = 0.0039）。物种相关性网络图分析显示与其他门类菌群相比,拟杆菌门、厚壁菌门、变形菌门与其他物种的关联性最强（size = 52.07、18.87、14.01）。组间差异基因进行GO功能显著性富集分析,差异基因均富集在如细胞学过程、刺激应答、生物学黏附及调节、代谢过程及信号通路等。KEGG功能显著性富集分析显示差异基因主要富集途径包括代谢途径、次生代谢物合成、淀粉和蔗糖的合成、抗生素的合成等。

COPD患者肠道内存在菌群及基因功能失调。

     

Proteinases in chronic obstructive pulmonary disease

Chronic obstructive pulmonary disease (COPD) is a major health problem worldwide, and we have little specific therapy to offer these patients. One potential strategy to limit loss of lung function in COPD would be to inhibit matrix-degrading proteinases. Several serine proteinases and matrix metalloproteinases are expressed in association with COPD in humans. Application of gene-targeted macrophage elastase and neutrophil elastase to a mouse model of cigarette-smoke-induced emphysema has uncovered roles for these proteinases in airspace enlargement, and has identified many interactions between these proteolytic systems.     

Association of current smoking with airway inflammation in chronic obstructive pulmonary disease and asymptomatic smokers

Background

Inflammation in the airways and lung parenchyma underlies fixed airway obstruction in chronic obstructive pulmonary disease. The exact role of smoking as promoting factor of inflammation in chronic obstructive pulmonary disease is not clear, partly because studies often do not distinguish between current and ex-smokers.

Methods

We investigated airway inflammation in sputum and bronchial biopsies of 34 smokers with chronic obstructive pulmonary disease (9 Global initiative for Chronic Obstructive Lung Disease stage 0, 9 stage I, 10 stage II and 6 stage III) and 26 asymptomatic smokers, and its relationship with past and present smoking habits and airway obstruction.

Results

Neutrophil percentage, interleukin-8 and eosinophilic-cationic-protein levels in sputum were higher in chronic obstructive pulmonary disease (stage I-III) than asymptomatic smokers. Inflammatory cell numbers in bronchial biopsies were similar in both groups. Current smoking correlated positively with macrophages: in bronchial biopsies in both groups, and in sputum in chronic obstructive pulmonary disease. Pack-years smoking correlated positively with biopsy macrophages only in chronic obstructive pulmonary disease.

Conclusion

Inflammatory effects of current smoking may mask the underlying ongoing inflammatory process pertinent to chronic obstructive pulmonary disease. This may have implications for future studies, which should avoid including mixed populations of smokers and ex-smokers.     

Eotaxin in serum of patients with asthma or chronic obstructive pulmonary disease: relationship with eosinophil cationic protein and lung function

This study was undertaken to investigate the correlation between the serum ECP and the serum eotaxin level, and disease activity as evaluated with pulmonary function in patients with asthma or chronic obstructive pulmonary disease (COPD). 20 patients with stable asthma and 15 patients with COPD, and 15 subjects of the control group took part in this study. The analysis of ECP was performed according to the manufacturer's directions (Pharmacia Diagnostics AB, Uppsala, Sweden). The ELISA test was used to measure eotaxin levels in sserum (kits from R&D, USA). The levels of ECP were 16.9+/-6.3 microg/L in patients with asthma, 15.1+/-9.3 microg/L in patients with COPD and 11.8+/-6.2 microg/L in the control group (P<0.05). There was no significant difference in the asthma ECP level compared with the ECP level in COPD. There was a significant difference between the ECP plasma level in asthma compared with the ECP plasma level in the control group (p<0.05). The levels of eotaxin were 175.8+/-49.3 pg/mL in the control group. There was a correlation of ECP and the eotaxin level in asthma patients (r=+0.5, p<0.05). The percentage fall in FEV1 correlated with eotaxin level in asthma (r=-0.3, p<0.05) and with the eotaxin level in COPD (r=-0.5, p<0.05). Serum outcomes of eotaxin and ECP levels appear to be a useful indicator of atopic asthma, and might provide complementary data disease monitoring. Therefore, further investigations are required to clarify whether serum eotaxin measurements have a role in the clinical evaluation in COPD.     

Gait mechanics in patients with chronic obstructive pulmonary disease

Background

Chronic obstructive pulmonary disease (COPD) is characterized by the frequent association of disease outside the lung. The objective of this study was to determine the presence of biomechanical gait abnormalities in COPD patients compared to healthy controls while well rested and without rest.

Methods

Patients with COPD (N = 17) and aged-matched, healthy controls (N = 21) walked at their self-selected pace down a 10-meter walkway while biomechanical gait variables were collected. A one-minute rest was given between each of the five collected trials to prevent tiredness (REST condition). Patients with COPD then walked at a self-selected pace on a treadmill until the onset of self-reported breathlessness or leg tiredness. Subjects immediately underwent gait analysis with no rest between each of the five collected trials (NO REST condition). Statistical models with and without covariates age, gender, and smoking history were used.

Results

After adjusting for covariates, COPD patients demonstrated more ankle power absorption in mid-stance (P = 0.006) than controls during both conditions. Both groups during NO REST demonstrated increased gait speed (P = 0.04), stride length (P = 0.03), and peak hip flexion (P = 0.04) with decreased plantarflexion moment (P = 0.04) and increased knee power absorption (P = 0.04) as compared to REST. A significant interaction revealed that peak ankle dorsiflexion moment was maintained from REST to NO REST for COPD but increased for controls (P < 0.01). Stratifying by disease severity did not alter these findings, except that step width decreased in NO REST as compared to REST (P = 0.01). Standardized effect sizes of significant effects varied from 0.5 to 0.98.

Conclusions

Patients with COPD appear to demonstrate biomechanical gait changes at the ankle as compared to healthy controls. This was seen not only in increased peak ankle power absorption during no rest but was also demonstrated by a lack of increase in peak ankle dorsiflexion moment from the REST to the NO REST condition as compared to the healthy controls. Furthermore, a wider step width has been associated with fall risk and this could account for the increased incidence of falls in patients with COPD.     

Models of chronic obstructive pulmonary disease

Chronic obstructive pulmonary disease (COPD) is a major global health problem and is predicted to become the third most common cause of death by 2020. Apart from the important preventive steps of smoking cessation, there are no other specific treatments for COPD that are as effective in reversing the condition, and therefore there is a need to understand the pathophysiological mechanisms that could lead to new therapeutic strategies. The development of experimental models will help to dissect these mechanisms at the cellular and molecular level. COPD is a disease characterized by progressive airflow obstruction of the peripheral airways, associated with lung inflammation, emphysema and mucus hypersecretion. Different approaches to mimic COPD have been developed but are limited in comparison to models of allergic asthma. COPD models usually do not mimic the major features of human COPD and are commonly based on the induction of COPD-like lesions in the lungs and airways using noxious inhalants such as tobacco smoke, nitrogen dioxide, or sulfur dioxide. Depending on the duration and intensity of exposure, these noxious stimuli induce signs of chronic inflammation and airway remodelling. Emphysema can be achieved by combining such exposure with instillation of tissue-degrading enzymes. Other approaches are based on genetically-targeted mice which develop COPD-like lesions with emphysema, and such mice provide deep insights into pathophysiological mechanisms. Future approaches should aim to mimic irreversible airflow obstruction, associated with cough and sputum production, with the possibility of inducing exacerbations.     

Molecular mechanisms in chronic obstructive pulmonary disease

Chronic obstructive pulmonary disease (COPD) is a chronic inflammatory lung disease associated with progressive airflow obstruction. Tobacco smoking is the main risk factor worldwide. In contrast to asthma, anti-inflammatory therapies are rather ineffective in improving chronic symptoms and reducing inflammation, lung function decline, and airway remodeling. Specific drugs that are directed against the remodeling and chronic inflammation, thereby preventing lung tissue damage and progressive lung function decline, must be developed. Experimental models and expression studies suggest that anti-vascular endothelial growth factor (VEGF) receptor strategies may be of use in patients with emphysema, whereas anti-HER1-directed strategies may be more useful in patients with pulmonary mucus hypersecretion, as seen in chronic bronchitis and asthma. Growth factors and cytokines including VEGF, fibroblast growth factors, transforming growth factor-β, tumor necrosis factor-α, CXCL1, CXCL8, and CCL2, and signal transduction proteins such as mitogen-activated protein kinase p38 and nuclear factor-⦊B, seem to be important pathogenetic molecules in COPD. Specific antagonists for these proteins may be effective for different inflammatory diseases. However, their efficacy for COPD therapy has not yet been demonstrated. Finally, other drugs such as retinoic acids may provide restoration of lung tissue structure. Such approaches, however, must await the first results of growth factor or cytokine antagonist therapy in chronic lung diseases.