Matrix metalloproteinase-9 promoter polymorphism associated with upper lung dominant emphysema

Antitrypsin deficiency: still more to learn about the lung after 60 years

The past 60 years have seen multiple publications related to lung disease in α1-antitrypsin deficiency largely reflecting the pathophysiology, biochemical effect and outcomes of augmentation therapy. However, the complexity of disease phenotype and the impact of the natural history presents problems of patient management, study design and hence interpretation of outcome. Although many national and some international registries exist, the lack of consistent in-depth assessment and importantly, the impact of augmentation therapy likely influences our perception of the true natural history. Development of new therapeutic strategies, and even assessment of the role and efficacy of augmentation, remain a challenge as powering such studies for conventional COPD outcomes is impractical due to relative rarity of the genetic condition and the presence of clinical phenotypic variation. The current review approaches these issues, discusses the nature and complexity of assessing patient variability, and provides guidance on further studies required to address them.

Associations of MMP9 polymorphism with the risk of severe pneumonia in a Southern Chinese children population

BACKGROUND

Severe pneumonia frequently causes irreversible sequelae and represents a major health burden for children under the age of 5. Matrix Metallopeptidase 9 (MMP9) is a zinc-dependent endopeptidase that is involved in various cellular processes. The correlation between MMP9 and the risk of severe childhood pneumonia remains unclear.

METHODS

Here we assemble a case-control cohort to study the association of genetic variants in MMP9 gene with severe childhood pneumonia susceptibility in a Southern Chinese population (1034 cases and 8426 controls).

RESULTS

Our results indicate that the allele G in rs3918262 SNP was significantly associated with an increased risk of severe pneumonia. Bioinformatic analyses by expression quantitative trait loci (eQTL), RegulomeDB and FORGEdb database analysis showed that rs3918262 SNP has potential regulatory effect on translational efficiency and protein level of MMP9 gene. Furthermore, MMP9 concentrations were significantly up-regulated in the bronchoalveolar lavages (BALs) of children with severe pneumonia.

CONCLUSION

In summary, our findings suggest that MMP9 is a novel predisposing gene for childhood pneumonia.

Quantitative Analysis for Lung Disease on Thin-Section CT

Thin-section computed tomography (CT) is widely employed not only for assessing morphology but also for evaluating respiratory function. Three-dimensional images obtained from thin-section CT provide precise measurements of lung, airway, and vessel volumes. These volumetric indices are correlated with traditional pulmonary function tests (PFT). CT also generates lung histograms. The volume ratio of areas with low and high attenuation correlates with PFT results. These quantitative image analyses have been utilized to investigate the early stages and disease progression of diffuse lung diseases, leading to the development of novel concepts such as pre-chronic obstructive pulmonary disease (pre-COPD) and interstitial lung abnormalities. Quantitative analysis proved particularly valuable during the COVID-19 pandemic when clinical evaluations were limited. In this review, we introduce CT analysis methods and explore their clinical applications in the context of various lung diseases. We also highlight technological advances, including images with matrices of 1024 × 1024 and slice thicknesses of 0.25 mm, which enhance the accuracy of these analyses.

Clinical characteristics and natural course of chronic obstructive pulmonary disease and/or asthma in Japanese patients: a summary report of two Hokkaido-based cohort studies

Chronic obstructive pulmonary disease (COPD) and asthma are the most common chronic airway diseases and are characterized by chronic airway inflammation and airflow limitation. Japanese patients with COPD or asthma have characteristics different from those of Westerners. Therefore, understanding the characteristics and clinical course of Japanese patients with COPD and those with asthma, particularly severe asthma, is critical for their management and appropriate treatment. The Hokkaido COPD cohort and Hokkaido-based Investigative Cohort Analysis for Refractory Asthma (Hi-CARAT) are high-quality cohort studies of COPD and asthma in the Japanese population and provide valuable data. This report summarizes the clinical findings from the two cohort studies and provides data for more appropriate management of Japanese patients with COPD and/or asthma. Overall, 279 patients with COPD were followed up for up to 10 years in the Hokkaido COPD cohort study, and 127 with severe asthma were followed up for up to 6 years in the Hi-CARAT study. Seventy-nine patients with mild-to-moderate asthma provided baseline data for the Hi-CARAT study. In each disease, several distinct factors, including systemic status and non-pulmonary factors, were associated with important clinical outcomes, such as lung function decline, exacerbations, impaired quality of life, and mortality. Therefore, multifaceted evaluation based on the characteristics of the Japanese population is necessary for the management of COPD and asthma.

Genetic Polymorphism of Matrix Metalloproteinase 9 and Susceptibility to Chronic Obstructive Pulmonary Disease: A Meta-analysis

Background

To systematically analyze the influence of genetic polymorphisms of matrix metalloproteinase 9 (MMP9) on susceptibility to chronic obstructive pulmonary disease (COPD).

Methods

Relevant literatures reporting MMP9 and susceptibility to COPD in PubMed, Web of Science, VIP, Wanfang and CNKI databases were searched using the key words "matrix metalloproteinases 9/MMP9, COPD/chronic obstructive pulmonary disease". Data of eligible literatures were extracted and analyzed for the odds ratio (OR) and corresponding 95% CI.

Results

A total of 16 independent studies reporting MMP9-1562C/T and COPD patients were enrolled and analyzed. None of the genetic models revealed the relationship between MMP9-1562C/T and susceptibility to COPD. Subgroup analyses identified lower risk of COPD in Chinese population carrying the TT genotype for theMMP9 rs3918242 relative to those carrying CT and CC genotypes (P=0.03, OR=0.67, 95% CI=0.46-0.97).

Conclusions

Chinese population carrying the TT genotype for the MMP-9 rs3918242 present lower susceptibility to COPD relative to those carrying CT and CC genotypes.

Dynamic Quantitative Magnetic Resonance Imaging Assessment of Areas of the Lung During Free-Breathing of Patients with Chronic Obstructive Pulmonary Disease

RATIONALE AND OBJECTIVES

Changes in the geometry of the chest wall due to lung hyperinflation occur in COPD. However, the quantitative assessment of impaired lung motions and its association with the clinical characteristics of COPD patients are unclear. This study aimed to investigate the respiratory kinetics of COPD patients by dynamic MRI.

MATERIALS AND METHODS

This study enrolled 22 COPD patients and 10 normal participants who underwent dynamic MRI and pulmonary function testing (PFT). Changes in the areas of the lung and mediastinum during respiration were compared between the COPD patients and the normal controls. Relationships between MRI, CT parameters, and clinical measures that included PFT results also were evaluated.

RESULTS

Asynchronous movements and decreased diaphragmatic motion were found in COPD patients. COPD patients had a larger ratio of MRI-measured lung areas at expiration to inspiration, a smaller magnitude of the peak area change ratio, and a smaller mediastinal-thoracic area ratio than the normal participants. The lung area ratio was associated with FEV₁/FVC, predicted RV%, and CT lung volume/predicted total lung capacity (pTLC). The lung area ratio of the right lower and left lower lungs was significantly correlated with emphysema of each lower lobe. The expiratory mediastinal-thoracic area ratio was associated with FEV₁% predicted and RV/TLC.

CONCLUSION

Changes in the lung areas of COPD patients as shown on MRI reflected the severity of airflow limitation, hyperinflation, and the extent of emphysema. Dynamic MRI provides essential information about respiratory kinetics in COPD.

Effects of time-controlled adaptive ventilation on cardiorespiratory parameters and inflammatory response in experimental emphysema

The time-controlled adaptive ventilation (TCAV) method attenuates lung damage in acute respiratory distress syndrome. However, so far, no study has evaluated the impact of the TCAV method on ventilator-induced lung injury (VILI) and cardiac function in emphysema. We hypothesized that the use of the TCAV method to achieve an expiratory flow termination/expiratory peak flow (E_FT/E_PF) of 25% could reduce VILI and improve right ventricular function in elastase-induced lung emphysema in rats. Five weeks after the last intratracheal instillation of elastase, animals were anesthetized and mechanically ventilated for 1 h using TCAV adjusted to either E_FT/E_PF 25% or E_FT/E_PF 75%, the latter often applied in ARDS. Pressure-controlled ventilation (PCV) groups with positive end-expiratory pressure levels similar to positive end-release pressure in TCAV with E_FT/E_PF 25% and E_FT/E_PF 75% were also analyzed. Echocardiography and lung ultrasonography were monitored. Lung morphometry, alveolar heterogeneity, and biological markers related to inflammation (interleukin [IL]-6, CINC-1), alveolar pulmonary stretch (amphiregulin), lung matrix damage (metalloproteinase [MMP]-9) were assessed. E_FT/E_PF 25% reduced respiratory system peak pressure, mean linear intercept, B lines at lung ultrasonography, and increased pulmonary acceleration time/pulmonary ejection time ratio compared with E_FT/E_PF 75%. The volume fraction of mononuclear cells, neutrophils, and expression of IL-6, CINC-1, amphiregulin, and MMP-9 were lower with E_FT/E_PF 25% than with E_FT/E_PF 75%. In conclusion, TCAV with E_FT/E_PF 25%, compared with E_FT/E_PF 75%, led to less lung inflammation, hyperinflation, and pulmonary arterial hypertension, which may be a promising strategy for patients with emphysema.

Cardiovascular Disease in Patients with Chronic Obstructive Pulmonary Disease, Obstructive Sleep Apnoea Syndrome and Overlap Syndrome

Chronic obstructive pulmonary disease (COPD) and obstructive sleep apnoea syndrome (OSAS) are among the most prevalent chronic respiratory disorders. Accumulating data suggest that there is a significant burden of cardiovascular disease (CVD) in patients with COPD and OSAS, affecting negatively patients' quality of life and survival. Overlap syndrome (OS), i.e. the co-existence of both COPD and OSAS in the same patient, has an additional impact on the cardiovascular system multiplying the risk of morbidity and mortality. The underlying mechanisms for the development of CVD in patients with either OSAS or COPD and OS are not entirely elucidated. Several mechanisms, in addition to smoking and obesity, may be implicated, including systemic inflammation, increased sympathetic activity, oxidative stress and endothelial dysfunction. Early diagnosis and proper management of these patients might reduce cardiovascular risk and improve patients' survival. In this review, we summarize the current knowledge regarding epidemiological aspects, pathophysiological mechanisms and present point-to-point specific associations between COPD, OSAS, OS and components of CVD, namely, pulmonary hypertension, coronary artery disease, peripheral arterial disease and stroke.

A Regulatory Role of Chemokine Receptor CXCR3 in the Pathogenesis of Chronic Obstructive Pulmonary Disease and Emphysema

Chronic obstructive pulmonary disease (COPD)/pulmonary emphysema is driven by the dysregulated airway inflammation and primarily influenced by the interaction between cigarette smoking (CS) and the individual's susceptibility. The inflammation in COPD involves both innate and adaptive immunity. By binding to its specific ligands, chemokine receptor CXCR3 plays an important role in regulating tissue inflammation and damage. In acute animal model challenged with either CS or pathogens, CXCR3 knockout (KO) attenuated lung inflammation and pathology. However, the role of CXCR3 in CS-induced chronic airway inflammation and pulmonary emphysema remains unknown. In this present study, we investigated the effect of CXCR3 in CS-induced pulmonary emphysema in an animal model, and the association between CXCR3 single nucleotide polymorphisms (SNPs) and COPD susceptibility in human subjects. We found that after chronic exposure to side stream CS (SSCS) for 24 weeks, CXCR3 KO mice demonstrated significant airspace enlargement expressed by mean linear intercept (Lm) compared with the wild-type (WT) mice. Consistently, CXCR3 KO mice had significantly higher BAL fluid macrophages and neutrophils, TNFα, and lung homogenate MMP-9 and MMP-12. Through genetic analysis of CXCR3 polymorphisms in a cohort of COPD patients with Han Chinese ethnicity, one CXCR3 SNP, rs2280964, was found to be genetically related to COPD susceptibility. Furthermore, CXCR3 SNP rs2280964 was significantly associated with the levels of serum MMP-9 in COPD patients. Our data from both animal and human studies revealed a novel role of CXCR3 possibly via influencing MMP9 production in the pathogenesis and progression of CS-associated COPD/pulmonary emphysema.

MMP-9-C1562T polymorphism and susceptibility to chronic obstructive pulmonary disease: A meta-analysis

BACKGROUND

To comprehensively evaluate the association between the polymorphism of matrix metalloproteinase-9 (MMP-9)-C1562T (rs3918242) and susceptibility to chronic obstructive pulmonary disease (COPD) in middle-aged and elderly patients through Meta-analysis.

METHODS

PubMed, EMBASE, CNKI, Wanfang, VIP, and other databases were searched by computer in the inception to August 2019 to collect all the case-control studies that met the inclusion criteria in this literature. Meta-analysis was performed using Stata 15.0, including the OR value calculations of the association between the merged MMP-9-C1562T polymorphism and the COPD susceptibility. Subgroup analysis, sensitivity analysis, and publication bias test were also performed. A total of 13 literature were included in this Meta-analysis with a total of 2512 cases and 2716 controls.

RESULTS

The results have shown that the OR of MMP-9-C1562T T allele to C allele was 0.35 (95% confidence interval [CI]: 0.23-0.52, P < .01). The subgroup analysis of ethnicity result showed that the merged OR of MMP-9-C1562T T allele to C allele was 0.24 (95% CI: 0.17-0.34, P < .01) in Caucasian while the merged OR was 0.62 (95% CI: 0.22-1.70, P > .05) in Asian. However, there were no statistically significant models in the dominant, recessive, homozygote and heterozygote genetic models.

CONCLUSION

The MMP-9-C1562T polymorphism was associated with the susceptibility to middle-aged and elderly COPD patients. Compared with T allele, C allele increased the risk of disease, especially in Caucasian, but not found in Asian.

Exploring the Association Between Emphysema Phenotypes and Low Bone Mineral Density in Smokers with and without COPD

Rationale

Emphysema and osteoporosis are tobacco-related diseases. Many studies have shown that emphysema is a strong and independent predictor of low bone mineral density (BMD) in smokers; however, none of them explored its association with different emphysema subtypes.

Objective

To explore the association between the different emphysema subtypes and the presence of low bone mineral density in a population of active or former smokers with and without chronic obstructive pulmonary disease (COPD).

Methods

One hundred and fifty-three active and former smokers from a pulmonary clinic completed clinical questionnaires, pulmonary function tests, a low-dose chest computed tomography (LDCT) and a dual-energy absorptiometry (DXA) scans. Subjects were classified as having normal BMD or low BMD (osteopenia or osteoporosis). Emphysema was classified visually for its subtype and severity. Logistic regression analysis explored the relationship between the different emphysema subtypes and the presence of low BMD adjusting for other important factors.

Results

Seventy-five percent of the patients had low BMD (78 had osteopenia and 37 had osteoporosis). Emphysema was more frequent (66.1 vs 26.3%, p=<0.001) and severe in those with low BMD. Multivariable analysis adjusting for other significant cofactors (age, sex, FEV₁, and severity of emphysema) showed that BMI (OR=0.91, 95% CI: 0.76–0.92) and centrilobular emphysema (OR=26.19, 95% CI: 1.71 to 399.44) were associated with low BMD.

Conclusion

Low BMD is highly prevalent in current and former smokers. BMI and centrilobular emphysema are strong and independent predictors of its presence, which suggests that they should be considered when evaluating smokers at risk for low BMD.

Influence of Emphysema and Air Trapping Heterogeneity on Pulmonary Function in Patients with COPD

Purpose

To explore the influence of emphysema and air trapping heterogeneity on pulmonary function changes in patients with stable chronic obstructive pulmonary disease (COPD).

Patients and methods

One hundred and seventy-nine patients with stable COPD were enrolled in this prospective study. All patients underwent low-dose inspiratory and expiratory CT scanning and pulmonary-function tests. CT quantitative data for the emphysema index (EI) on full-inspiration and air trapping (AT) on full-expiration were measured for the whole lung, the right and left lungs, and the cranial-caudal lung zones. The heterogeneity index (HI) values for emphysema and air trapping were determined as the ratio of the difference to the sum of the respective indexes. The cranial-caudal HI and left–right lung HI were compared between mild-to-moderate (GOLD stage I and II) and severe (GOLD stage III and IV) disease groups. The associations between HI and pulmonary-function measurements adjusted for age, sex, height, smoking history, EI and AT of the total lung were assessed using multiple linear regression analysis.

Results

The absolute values for cranial-caudal HI (AT_CC_HI) and left–right lung HI (AT_LR_HI) on full-expiration were significantly larger in the mild-to-moderate group, while no significant intergroup differences were observed on full-inspiration. COPD patients with lower-zone and/or left-lung predominance showed significantly lower pulmonary function than those with upper-zone and/or right-lung predominance on full-expiration, whereas no significant differences were observed on full-inspiration. The absolute values of AT_CC_HI and AT_LR_HI significantly correlated with pulmonary-function measurements. Higher AT_CC_HI and lower AT_LR_HI absolute values indicated better pulmonary function, after adjusting for age, sex, height, smoking history, EI and AT of the total lung.

Conclusion

Subjects with more heterogeneous distribution and/or upper-zone predominant and/or right-lung predominant patterns on full-expiration tend to have better pulmonary function. Thus, in comparison with emphysema heterogeneity, AT heterogeneity better reflects the pulmonary function changes in COPD patients.

MMP2 and MMP10 Polymorphisms Are Related to Steroid-Induced Osteonecrosis of the Femoral Head among Chinese Han Population

Background

Steroid-induced osteonecrosis of the femoral head is a relatively serious condition which seriously reduces patient quality of life. However, the pathogenesis of steroid-induced ONFH is still unclear. In recent years, more scholars have found that the pathogenesis of steroid-induced ONFH is related to susceptibility factors such as MMPs/TIMPs system. The main purpose of this study is to investigate the correlation between MMP2 and MMP10 gene polymorphisms and steroid-induced ONFH in Chinese Han population.

Methods

Six SNPs in MMP2 and two SNPs in MMP10 were genotyped using Agena MassARRAY RS1000 system from 286 patients of steroid-induced ONFH and in 309 healthy controls. The association between MMP2 and MMP10 polymorphisms and steroid-induced ONFH risk were estimated by the Chi-squared test, genetic model analysis, haplotype analysis, and stratification analysis. The relative risk was estimated by odd ratios (ORs) and 95% confidence intervals (CIs).

Result

We found that the minor TG allele of rs470154 in MMP10 was associated with an increased risk of steroid-induced ONFH (OR = 1.45, 95% CI, 1.03 – 2.05, p = 0.032). In the genetic model analysis, we found that rs2241146 in MMP2 gene and rs470154 in MMP10 gene showed a statistically significant association with increased risk of steroid-induced ONFH. The six SNPs (rs470154, rs243866, rs243864, rs865094, rs11646643, and rs2241146) showed a statistically significant association with different clinical phenotypes.

Conclusion

Our results verify that genetic polymorphisms of MMP2 and MMP10 contribute to steroid-induced ONFH susceptibility in the population of Chinese Han population, and our study provides new insights into the role that MMP2 and MMP10 plays in the mechanism of ONFH.

Impact of Matrix Metalloproteinase 9 on COPD Development in Polish Patients: Genetic Polymorphism, Protein Level, and Their Relationship with Lung Function

Chronic obstructive pulmonary disease (COPD) is characterized by a decline of lung function and symptoms such as chronic bronchitis and emphysema leading from lung tissue destruction. Increased activity of matrix metalloproteinases (MMPs) and an imbalance between MMPs and their tissue inhibitors (TIMPs) are considered as factors influencing the pathogenesis of COPD. We investigated the role of genetic polymorphism and expression level of MMP-9 and concentration of its complexes with TIMPs in the development of COPD among Polish patients. We analyzed SNP in the promoter region of MMP-9 gene (rs3918242) using PCR-RFLP method among 335 COPD patients and 309 healthy individuals. Additionally, 60 COPD patients and 61 controls were tested for copy number variants (CNV) of MMP-9 (by quantitative real-time PCR) and serum levels of MMP-9 and its complexes with TIMP1 and TIMP2 (using ELISA). All subjects were analyzed for lung function using spirometry (FEV₁% and FEV₁/FVC parameters). We observed that allele and genotype frequencies of the SNP rs3918242, as well as the number of gene copies, were similar in COPD patient and controls groups. Serum levels of MMP-9 and MMP-9/TIMP1 complex were significantly higher in COPD patients in comparison to controls groups, although independently of analyzed gene polymorphisms. Additionally, the significant inverse relationships between parameters of lung function (FEV₁% and FEV₁/FVC) and proteins level were found in ridge regression models, especially we found that FEV₁% decreased when MMP-9 level increased in controls and patients with COPD group. In conclusion, we found that COPD patients were predisposed to produce more MMP-9 and MMP-9/TIMP1 complex than healthy individuals. This phenomenon is probably associated with the disease-related lung environment but not with genetic features of the MMP-9.

Complementary regional heterogeneity information from COPD patients obtained using oxygen-enhanced MRI and chest CT

Background

The heterogeneous distribution of emphysema is a key feature of chronic obstructive pulmonary disease (COPD) patients that typically is evaluated using high-resolution chest computed tomography (HRCT). Oxygen-enhanced pulmonary magnetic resonance imaging (OEMRI) is a new method to obtain information regarding regional ventilation, diffusion, and perfusion in the lung without radiation exposure. We aimed to compare OEMRI with HRCT for the assessment of heterogeneity in COPD patients.

Methods

Forty patients with stable COPD underwent quantitative HRCT, OEMRI, and pulmonary function tests, including arterial blood gas analysis. OEMRI was also performed on nine healthy control subjects. We measured the severity of emphysema (percent low attenuation volume; LAV%) in whole lungs and the standard deviations (SDs) of the LAV% values of 10 isovolumetric partitions (SD-LAV) as an index of cranial-caudal heterogeneity. Similarly, relative enhancement ratios of oxygen (RERs) in whole lungs from OEMRI and SD-RER were analyzed.

Results

COPD patients showed a lower mean RER than control subjects (12.6% vs 22.0%, p<0.01). The regional heterogeneity of the RERs was not always consistent with the LAV distribution. Both the HRCT (LAV% and SD-LAV) and the OEMRI (RER and SD-RER) indices were significantly associated with the diffusion capacity (DL_CO) and partial pressure of oxygen in arterial blood (PaO₂). The PaO₂ was associated only with the heterogeneity index of HRCT (SD-LAV) (R² = 0.39); however, the PaO₂ was associated with both the mean RER and heterogeneity (SD-RER) in the multivariate analysis (R² = 0.38).

Conclusions

OEMRI-derived parameters were directly associated with oxygen uptake in COPD patients. Although the OEMRI-derived parameters were not identical to the HRCT-derived parameters, the cranial-caudal heterogeneity in HRCT or OEMRI was complementary to that in evaluations of oxygen uptake in the lungs. Functional imaging seems to provide new insights into COPD pathophysiology without radiation exposure.

The cytoprotective role of DJ-1 and p45 NFE2 against human primary alveolar type II cell injury and emphysema

Emphysema is characterized by irreversibly enlarged airspaces and destruction of alveolar walls. One of the factors contributing to this disease pathogenesis is an elevation in extracellular matrix (ECM) degradation in the lung. Alveolar type II (ATII) cells produce and secrete pulmonary surfactants and proliferate to restore the epithelium after damage. We isolated ATII cells from control non-smokers, smokers and patients with emphysema to determine the role of NFE2 (nuclear factor, erythroid-derived 2). NFE2 is a heterodimer composed of two subunits, a 45 kDa (p45 NFE2) and 18 kDa (p18 NFE2) polypeptides. Low expression of p45 NFE2 in patients with emphysema correlated with a high ECM degradation. Moreover, we found that NFE2 knockdown increased cell death induced by cigarette smoke extract. We also studied the cross talk between p45 NFE2 and DJ-1. DJ-1 protein is a redox-sensitive chaperone that protects cells from oxidative stress. We detected that cigarette smoke significantly increased p45 NFE2 levels in DJ-1 KO mice compared to wild-type mice. Our results indicate that p45 NFE2 expression is induced by exposure to cigarette smoke, has a cytoprotective activity against cell injury, and its downregulation in human primary ATII cells may contribute to emphysema pathogenesis.

Lobar Emphysema Distribution Is Associated With 5-Year Radiological Disease Progression

BACKGROUND

Emphysema has considerable variability in its regional distribution. Craniocaudal emphysema distribution is an important predictor of the response to lung volume reduction. However, there is little consensus regarding how to define upper lobe-predominant and lower lobe-predominant emphysema subtypes. Consequently, the clinical and genetic associations with these subtypes are poorly characterized.

METHODS

We sought to identify subgroups characterized by upper-lobe or lower-lobe emphysema predominance and comparable amounts of total emphysema by analyzing data from 9,210 smokers without alpha-1-antitrypsin deficiency in the Genetic Epidemiology of COPD (COPDGene) cohort. CT densitometric emphysema was measured in each lung lobe. Random forest clustering was applied to lobar emphysema variables after regressing out the effects of total emphysema. Clusters were tested for association with clinical and imaging outcomes at baseline and at 5-year follow-up. Their associations with genetic variants were also compared.

RESULTS

Three clusters were identified: minimal emphysema (n = 1,312), upper lobe-predominant emphysema (n = 905), and lower lobe-predominant emphysema (n = 796). Despite a similar amount of total emphysema, the lower-lobe group had more severe airflow obstruction at baseline and higher rates of metabolic syndrome compared with subjects with upper-lobe predominance. The group with upper-lobe predominance had greater 5-year progression of emphysema, gas trapping, and dyspnea. Differential associations with known COPD genetic risk variants were noted.

CONCLUSIONS

Subgroups of smokers defined by upper-lobe or lower-lobe emphysema predominance exhibit different functional and radiological disease progression rates, and the upper-lobe predominant subtype shows evidence of association with known COPD genetic risk variants. These subgroups may be useful in the development of personalized treatments for COPD.

Deoxyribonuclease 1 reduces pathogenic effects of cigarette smoke exposure in the lung

Our aim was to investigate if deoxyribonuclease (DNase) 1 is a potential therapeutic agent to reduce pathogenic effects of cigarette smoke exposure in the lung. Cigarette smoke causes protease imbalance with excess production of proteases, which is a key process in the pathogenesis of emphysema. The mechanisms responsible for this effect are not well-defined. Our studies demonstrate both in vitro and in vivo that cigarette smoke significantly increases the expression of neutrophil and macrophage extracellular traps with coexpression of the pathogenic proteases, neutrophil elastase and matrix metalloproteinases 9 and 12. This response to cigarette smoke was significantly reduced by the addition of DNase 1, which also significantly decreased macrophage numbers and lung proteolysis. DNase 1, a treatment currently in clinical use, can diminish the pathogenic effects of cigarette smoke.

Effect of Liuweibuqi capsules on the balance between MMP-9 and TIMP1 and viability of alveolar macrophages in COPD

The present study aims to investigate the effect of Liuweibuqi (LWBQ) capsules on the expression of matrix metalloproteinase (MMP)-9 and TIMP1 and cell viability of alveolar macrophages (AMs) in chronic obstructive pulmonary disease (COPD). Rats were randomly divided into normal control (NC) group, model control (MC) group, Jinshuibao (JSB) group, spleen aminopeptidase (PAT) group, and low dose of LWBQ (LWBQ low), mid dose of LWBQ (LWBQ mid), and high dose of LWBQ (LWBQ high) group (n=10). Lung function was measured with a spirometer. Serum cytokines including tumor necrosis factor-α (TNF-α) and interleukin-6 (IL-6) were detected using ELISA. The expressions of MMP-9 and TIMP1 were detected by quantitative real-time PCR (qRT-PCR) and Western blot. MTT assay and flow cytometry were used to measure cell viability and apoptosis. Compared with the NC group, body weight and lung function were reduced in the MC group. In addition, the serum levels of IL-6 and TNF-α were higher in the MC group than those in the NC group. The expression of MMP-9 protein in the AMs from rats was higher, and TIMP1 protein was lower in the MC group compared with the NC group. After LWBQ capsules treatment, compared with the MC group, the expression of inflammatory cytokines and MMP-9 were lower and TIMP1 was higher. Moreover, after LWBQ-medicated serum treatment, the release of inflammatory cytokines was reduced from AMs. Besides, LWBQ-medicated serum decreased the expression of MMP-9 and increased the expression of TIMP1 and cell viability compared with those in MC group. In conclusion, LWBQ capsules can inhibit the release of inflammatory cytokines, promote cell viability in AMs, and regulate the expression of MMP-9 and TIMP1.

Genome-Wide Association Study of the Genetic Determinants of Emphysema Distribution

RATIONALE

Emphysema has considerable variability in the severity and distribution of parenchymal destruction throughout the lungs. Upper lobe-predominant emphysema has emerged as an important predictor of response to lung volume reduction surgery. Yet, aside from alpha-1 antitrypsin deficiency, the genetic determinants of emphysema distribution remain largely unknown.

OBJECTIVES

To identify the genetic influences of emphysema distribution in non-alpha-1 antitrypsin-deficient smokers.

METHODS

A total of 11,532 subjects with complete genotype and computed tomography densitometry data in the COPDGene (Genetic Epidemiology of Chronic Obstructive Pulmonary Disease [COPD]; non-Hispanic white and African American), ECLIPSE (Evaluation of COPD Longitudinally to Identify Predictive Surrogate Endpoints), and GenKOLS (Genetics of Chronic Obstructive Lung Disease) studies were analyzed. Two computed tomography scan emphysema distribution measures (difference between upper-third and lower-third emphysema; ratio of upper-third to lower-third emphysema) were tested for genetic associations in all study subjects. Separate analyses in each study population were followed by a fixed effect metaanalysis. Single-nucleotide polymorphism-, gene-, and pathway-based approaches were used. In silico functional evaluation was also performed.

MEASUREMENTS AND MAIN RESULTS

We identified five loci associated with emphysema distribution at genome-wide significance. These loci included two previously reported associations with COPD susceptibility (4q31 near HHIP and 15q25 near CHRNA5) and three new associations near SOWAHB, TRAPPC9, and KIAA1462. Gene set analysis and in silico functional evaluation revealed pathways and cell types that may potentially contribute to the pathogenesis of emphysema distribution.

CONCLUSIONS

This multicohort genome-wide association study identified new genomic loci associated with differential emphysematous destruction throughout the lungs. These findings may point to new biologic pathways on which to expand diagnostic and therapeutic approaches in chronic obstructive pulmonary disease. Clinical trial registered with www.clinicaltrials.gov (NCT 00608764).

The Role of Matrix Metalloproteinases in Development, Repair, and Destruction of the Lungs

Normal gas exchange after birth requires functional lung alveolar units that are lined with epithelial cells, parts of which are intricately fused with microvascular capillaries. A significant phase of alveolar lung development occurs in the perinatal period, continues throughout early stages in life, and requires activation of matrix-remodeling enzymes. Failure to achieve an optimum number of alveoli during lung maturation can cause several untoward medical consequences including disabling obstructive and/or restrictive lung diseases that limit physiological endurance and increase mortality. Several members of the matrix metalloproteinase (MMP) family are critical in lung remodeling before and after birth; however, their resurgence in response to environmental factors, infection, and injury can also compromise lung function. Therefore, temporal expression, regulation, and function of MMPs play key roles in developing and maintaining adequate oxygenation under steady state, as well as in diseased conditions. Broadly, with the exception of MMP2 and MMP14, most deletional mutations of MMPs fail to perturb lung development; however, their individual absence can alter the pathophysiology of respiratory diseases. Specifically, under stressed conditions such as acute respiratory infection and allergic inflammation, MMP2 and MMP9 can play a protective role through bacterial clearance and production of chemotactic gradient, while loss of MMP12 can protect mice from smoke-induced lung disease. Therefore, better understanding of the expression and function of MMPs under normal lung development and their resurgence in response respiratory diseases could provide new therapeutic options in the future.

Genetic polymorphism and chronic obstructive pulmonary disease

Chronic obstructive pulmonary disease (COPD) is a common chronic disease, and its morbidity and mortality are increasing. There are many studies that have tried to explain the pathogenesis of COPD from genetic susceptibility, to identify the susceptibility of COPD factors, which play a role in early prevention, early detection and the early treatment. However, it is well known that COPD is an inflammatory disease characterized by incomplete reversible airflow limitation in which genes interact with the environment. In recent years, many studies have proved gene polymorphisms and COPD correlation. However, there is less research on the relationship between COPD and genome-wide association study (GWAS), epigenetics and apoptosis. In this paper, we summarized the correlation between gene level and COPD from the following four aspects: the GWAS, the gene polymorphism, the epigenetics and the apoptosis, and the relationship between COPD and gene is summarized comprehensively.

Genetic polymorphism in matrix metalloproteinase-9 and transforming growth factor-β1 and susceptibility to combined pulmonary fibrosis and emphysema in a Chinese population

In this study, we aimed to explore the association of genetic polymorphism in matrix metalloproteinase-9 (MMP-9) and transforming growth factor-β1 (TGF-β1) and the susceptibility to combined pulmonary fibrosis and emphysema (CPFE). We examined the polymorphisms of the MMP-9 C-1562T and TGF-β1 T869C in 38 CPFE patients, 50 pulmonary emphysema patients, and 34 idiopathic pulmonary fibrosis (IPF) patients. The frequencies of polymorphic genotypes in MMP-9 were 78.95% CC and 21.05% CT in CPFE group, 76.0% CC and 24.0% CT in emphysema group, and 100.0% CC in IPF group. There were highly statistically significant increased frequencies of the CT genotype and T allele in CPFE and emphysema groups compared with IPF group (p < 0.05). The frequencies of polymorphic genotypes in TGF-β1 were 2.63% CC, 28.95% CT, 68.42% TT in CPFE group, 4.00% CC, 16.00% CT, 80.00% TT in emphysema group, and 5.88% CC, 41.18% CT, 52.94% TT in IPF group. Significant increases in the TT genotype and T allele frequencies were observed in emphysema group compared with IPF group (p < 0.05). Our study has showed that T allele in MMP-9 (C-1562T) and T allele in TGF-β1 (T869C) are risk factors of pulmonary emphysema. The T allele in MMP-9 (C-1562T) possibly predisposes patients with pulmonary fibrosis to develop emphysema.

Advances in Identifying Urine/Serum Biomarkers in Alpha-1 Antitrypsin Deficiency for More Personalized Future Treatment Strategies

Alpha1-antitrypsin deficiency (AATD) is a genetic disorder characterized by reduced serum levels of alpha1-antitrypsin (AAT) and increased risk for developing both early-onset lung emphysema and chronic liver disease. Laboratory diagnosis of AATD is not just a matter of degree, although the AAT serum level is the most important determinant for risk of lung damage. While being a single-gene disease, the clinical phenotype of AATD is heterogeneous. The current standard of care for patients affected by AATD-associated pulmonary emphysema is replacement therapy with weekly i.v. infusions of pooled human purified plasma AAT. Although no treatment for liver disease caused by deposition of abnormal AAT in hepatocytes is available, innovative treatments for this condition are on the horizon. This article aims to provide a critical review of the methodological steps that have marked progress in the detection of indicators described in the literature as being "clinically significant" biomarkers of the disease. The development and routine use of specific biomarkers would help both in identifying which patients and when they are eligible for treatment as well as providing additional parameters for monitoring the disease.

Gene-environment interaction between the MMP9 C-1562T promoter variant and cigarette smoke in the pathogenesis of chronic obstructive pulmonary disease

The aetiology of chronic obstructive pulmonary disease (COPD) is complex. While cigarette smoking is a well-established cause of COPD, a myriad of assessed genetic factors has given conflicting data. Since gene-environment interactions are thought to be implicated in aetiopathogenesis of COPD, we aimed to examine the matrix metalloproteinase (MMP) 9 C-1562T (rs3918242) functional variant and cigarette smoke in the pathogenesis of this disease. The distribution of the MMP9 C-1562T variant was analyzed in COPD patients and controls with normal pulmonary function from Serbia. Interaction between the C-1562T genetic variant and cigarette smoking was assessed using a case-control model. The response of the C-1562T promoter variant to cigarette smoke condensate (CSC) exposure was examined using a dual luciferase reporter assay. The frequency of T allele carriers was higher in the COPD group than in smoker controls (38.4% vs. 20%; OR = 2.7, P = 0.027). Interaction between the T allele and cigarette smoking was identified in COPD occurrence (OR = 4.38, P = 0.005) and severity (P = 0.001). A functional analysis of the C-1562T variant demonstrated a dose-dependent and allele-specific response (P < 0.01) to CSC. Significantly higher MMP9 promoter activity following CSC exposure was found for the promoter harboring the T allele compared to the promoter harboring the C allele (P < 0.05). Our study is the first to reveal an interaction between the MMP9-1562T allele and cigarette smoke in COPD, emphasising gene-environment interactions as a possible cause of lung damage in the pathogenesis of COPD. Environ. Mol. Mutagen. 57:447-454, 2016. © 2016 Wiley Periodicals, Inc.

Relationship between pulmonary matrix metalloproteinases and quantitative CT markers of small airways disease and emphysema in COPD

BACKGROUND

Matrix metalloproteinases (MMPs) are proteolytic enzymes that can degrade the extracellular matrix and drive tissue remodelling, key processes in the pathogenesis of COPD. The development of small airway disease has been identified as a critical mechanism in the early development of airflow obstruction but the contribution of MMPs in human disease is poorly characterised.

OBJECTIVES

We investigated the role of MMPs and inflammatory cytokines in the lung by quantifying levels and determining relationships with the key pathological components of COPD in patients and healthy controls.

METHODS

We analysed levels of MMPs and inflammatory cytokines in bronchoalveolar lavage from 24 COPD and 8 control subjects. Each subject underwent spirometry and high-resolution CT. Image analysis quantitatively assessed emphysema, bronchial wall thickening and small airways disease.

RESULTS

Multiple MMPs (MMP-1, -2, -3, -8, -9 and -10) and cytokines (interleukin (IL) 6 and IL-8) were elevated in lungs of subjects with COPD. MMP-3, -7, -8, -9, -10 and -12 concentrations closely associated with CT markers of small airways disease. Emphysema severity was also associated with MMP-3, -7 and -10. However, there were no strong relationships between MMPs and bronchial wall thickness of the larger airways.

CONCLUSIONS

Pulmonary MMP concentrations are directly associated with the extent of gas trapping and small airways disease identified on CT scan. This study suggests that MMPs play a significant role in small airways remodelling, a key feature in the pathogenesis of COPD.

TRIAL REGISTRATION NUMBER

NCT01701869.

Genetic polymorphisms of matrix metalloproteinases and protein levels in chronic obstructive pulmonary disease in a Mexican population

AIM

To evaluate association of single nucleotide polymorphisms (SNPs) in the MMP1, MMP2, MMP9 and MMP12 genes and serum MMP-2 and MMP-9 levels in smoking chronic obstructive pulmonary disease (COPD) patients.

MATERIALS & METHODS

Genotyping using real-time PCR in 330 smokers with COPD (COPD), 658 smokers without COPD (SNC) and 150 nonsmokers (NCNS), the analysis of samples used was χ(2) test. Using ELISA, the proteins were evaluated. Multiple comparisons were made by ANOVA.

RESULTS

rs243864 (OR: 7.44; 95% CI: 3.62-15.26) and rs11646643 (OR: 1.58; 95% CI: 1.07-2.34) of the MMP-2 gene and rs3918253 (OR: 1.72; 95% CI: 1.08-2.71) of the MMP-9 gene, were associated with the risk of COPD. Serum MMP-2 level in the COPD group was lower compared with SNC (p < 0.05). Serum MMP-9 level was elevated in the COPD group compared with SNC (p < 0.05).

CONCLUSION

Polymorphisms in MMP2 and MMP9 but not in MMP1 and MMP12 are associated with the risk of COPD in the Mexican mestizo population.

High-density lipoproteins potentiate α1-antitrypsin therapy in elastase-induced pulmonary emphysema

Several studies report that high-density lipoproteins (HDLs) can carry α1-antitrypsin (AAT; an elastase inhibitor). We aimed to determine whether injection of exogenous HDL, enriched or not in AAT, may have protective effects against pulmonary emphysema. After tracheal instillation of saline or elastase, mice were randomly treated intravenously with saline, human plasma HDL (75 mg apolipoprotein A1/kg), HDL-AAT (75 mg apolipoprotein A1-3.75 mg AAT/kg), or AAT alone (3.75 mg/kg) at 2, 24, 48, and 72 hours. We have shown that HDL-AAT reached the lung and prevented the development of pulmonary emphysema by 59.3% at 3 weeks (alveoli mean chord length, 22.9 ± 2.8 μm versus 30.7 ± 4.5 μm; P < 0.001), whereas injection of HDL or AAT alone only showed a moderate, nonsignificant protective effect (28.2 ± 4.2 μm versus 30.7 ± 5 μm [P = 0.23] and 27.3 ± 5.66 μm versus 30.71 ± 4.96 μm [P = 0.18], respectively). Indeed, protection by HDL-AAT was significantly higher than that observed with HDL or AAT (P = 0.006 and P = 0.048, respectively). This protective effect was associated (at 6, 24, and 72 h) with: (1) a reduction in neutrophil and macrophage number in the bronchoalveolar lavage fluid; (2) decreased concentrations of IL-6, monocyte chemoattractant protein-1, and TNF-α in both bronchoalveolar lavage fluid and plasma; (3) a reduction in matrix metalloproteinase-2 and matrix metalloproteinase-9 activities; and (4) a reduction in the degradation of fibronectin, a marker of tissue damage. In addition, HDL-AAT reduced acute cigarette smoke-induced inflammatory response. Intravenous HDL-AAT treatment afforded a better protection against elastase-induced pulmonary emphysema than AAT alone, and may represent a significant development for the management of emphysema associated with AAT deficiency.

Impact of emphysema heterogeneity on pulmonary function

Objectives

To investigate the association between emphysema heterogeneity in spatial distribution, pulmonary function and disease severity.

Methods and Materials

We ascertained a dataset of anonymized Computed Tomography (CT) examinations acquired on 565 participants in a COPD study. Subjects with chronic bronchitis (CB) and/or bronchodilator response were excluded resulting in 190 cases without COPD and 160 cases with COPD. Low attenuations areas (LAAs) (≤950 Hounsfield Unit (HU)) were identified and quantified at the level of individual lobes. Emphysema heterogeneity was defined in a manner that ranged in value from −100% to 100%. The association between emphysema heterogeneity and pulmonary function measures (e.g., FEV1% predicted, RV/TLC, and DLco% predicted) adjusted for age, sex, and smoking history (pack-years) was assessed using multiple linear regression analysis.

Results

The majority (128/160) of the subjects with COPD had a heterogeneity greater than zero. After adjusting for age, gender, smoking history, and extent of emphysema, heterogeneity in depicted disease in upper lobe dominant cases was positively associated with pulmonary function measures, such as FEV1 Predicted (p<.001) and FEV1/FVC (p<.001), as well as disease severity (p<0.05). We found a negative association between HI% , RV/TLC (p<0.001), and DLco% (albeit not a statistically significant one, p = 0.06) in this group of patients.

Conclusion

Subjects with more homogeneous distribution of emphysema and/or lower lung dominant emphysema tend to have worse pulmonary function.

Senescence is involved in the pathogenesis of chronic obstructive pulmonary disease through effects on telomeres and the anti-aging molecule fibroblast growth factor 23

AIM

Fibroblast growth factor 23 knockout mice develop premature aging and emphysema, indicating that dysregulation of the normal aging process is involved in the pathobiology of chronic obstructive pulmonary disease. Thus, we explored the association among a coding single-nucleotide polymorphism of fibroblast growth factor 23, its protein concentration in serum and telomere length in patients with chronic obstructive pulmonary disease.

METHODS

The study involved 361 smokers; among whom, 244 were patients with chronic obstructive pulmonary disease. We genotyped a coding single-nucleotide polymorphism of fibroblast growth factor 23, rs7955866, and measured the telomere length of the peripheral blood cells. We also determined emphysema severity and airflow obstruction using computed tomography and pulmonary function tests, respectively. Furthermore, we analyzed the association between the disease phenotypes and fibroblast growth factor 23 genotypes or telomere length of peripheral blood leukocytes, as well as the association between the serum level of the studied protein and its genotypes.

RESULTS

The mice with A alleles on rs7955866 showed severe upper lung emphysema (P = 0.008). The serum concentration of the tested protein was lower in the mice with A allele than in the G homozygotes (P = 0.004). Telomere shortening was associated with airflow obstruction (P = 0.009), but not with upper lung emphysema.

CONCLUSIONS

A variation of fibroblast growth factor 23 with a reduced serum concentration appeared to promote emphysema formation. Telomere shortening in peripheral blood leukocytes was not associated with emphysema, but with airflow obstruction in chronic obstructive pulmonary disease through an independent mechanism.

Biomarkers in chronic obstructive pulmonary disease: confusing or useful?

The field of biomarker research has almost reached unmanageable proportions in chronic obstructive pulmonary disease (COPD). The developments of new technology platforms have generated a huge information data base, both cross sectionally and increasingly, longitudinally. The knowledge emerging provides an enormous potential for understanding the disease pathophysiology, for developing markers specific for long-term outcomes, and for developing new therapeutic strategies. However, the excitement must be tempered with an understanding of the limitations of the data collection techniques, and of the variations in disease state, activity, impact, and progression. Nevertheless, the most crucial aspect in interpreting the current literature is the recognition of the relatively superficial characterization of what is a complex group of pathological processes with a common end point of airflow limitation. The current review explores some of these issues together with those areas where real progress appears to have been made, and provides caution on interpretation.

Genetic susceptibility

Why only 20% of smokers develop clinically relevant chronic obstructive pulmonary disease (COPD) was a puzzle for many years. Now, epidemiologic studies point clearly toward a large heritable component. The combination of genome-wide association studies and candidate gene analysis is helping to identify those genetic variants responsible for an individual's susceptibility to developing COPD. In this review, the current data implicating specific loci and genes in the pathogenesis of COPD are examined.

Emphysema and mechanical stress-induced lung remodeling

Transpulmonary pressure and the mechanical stresses of breathing modulate many essential cell functions in the lung via mechanotransduction. We review how mechanical factors could influence the pathogenesis of emphysema. Although the progression of emphysema has been linked to mechanical rupture, little is known about how these stresses alter lung remodeling. We present possible new directions and an integrated multiscale view that may prove useful in finding solutions for this disease.

Distinct quantitative computed tomography emphysema patterns are associated with physiology and function in smokers

RATIONALE

Emphysema occurs in distinct pathologic patterns, but little is known about the epidemiologic associations of these patterns. Standard quantitative measures of emphysema from computed tomography (CT) do not distinguish between distinct patterns of parenchymal destruction.

OBJECTIVES

To study the epidemiologic associations of distinct emphysema patterns with measures of lung-related physiology, function, and health care use in smokers.

METHODS

Using a local histogram-based assessment of lung density, we quantified distinct patterns of low attenuation in 9,313 smokers in the COPDGene Study. To determine if such patterns provide novel insights into chronic obstructive pulmonary disease epidemiology, we tested for their association with measures of physiology, function, and health care use.

MEASUREMENTS AND MAIN RESULTS

Compared with percentage of low-attenuation area less than -950 Hounsfield units (%LAA-950), local histogram-based measures of distinct CT low-attenuation patterns are more predictive of measures of lung function, dyspnea, quality of life, and health care use. These patterns are strongly associated with a wide array of measures of respiratory physiology and function, and most of these associations remain highly significant (P < 0.005) after adjusting for %LAA-950. In smokers without evidence of chronic obstructive pulmonary disease, the mild centrilobular disease pattern is associated with lower FEV1 and worse functional status (P < 0.005).

CONCLUSIONS

Measures of distinct CT emphysema patterns provide novel information about the relationship between emphysema and key measures of physiology, physical function, and health care use. Measures of mild emphysema in smokers with preserved lung function can be extracted from CT scans and are significantly associated with functional measures.

Genetic polymorphism of matrix metalloproteinase family and chronic obstructive pulmonary disease susceptibility: a meta-analysis

Matrix metalloproteinase (MMP) family is considered to be associated with chronic obstructive pulmonary disease (COPD) pathogenesis, however, no consistent results have been provided by previous studies. In this report, we performed Meta analysis to investigate the association between four kinds of MMP single nucleotide polymorphisms (SNP, MMP1 -1607 1G/2G, MMP3 -1171 5A/6A, MMP9 -1562 C/T, MMP12 -82 A/G) and COPD risk from 21 studies including 4184 cases and 5716 controls. Both overall and subgroup association between SNP and COPD susceptibility were tested. There was no evident association between MMP polymorphisms and COPD susceptibility in general population. On the other hand, subgroup analysis suggested that MMP9 -1562 C/T polymorphism was related to COPD, as we found that C allele carriers were at lower risk in some subgroups stratified by lung function, age and genotype identification method, compared with TT homozygotes. Our results indicated the genotype TT might be one genetic risk factor of severe COPD.

The role of macrophages in obstructive airways disease: chronic obstructive pulmonary disease and asthma

Macrophages are a major cellular component of the innate immune system, and play an important role in the recognition of microbes, particulates, and immunogens and to the regulation of inflammatory responses. In the lung, macrophages react with soluble proteins that bind microbial products in order to remove pathogens and particles and to maintain the sterility of the airway tract. Chronic obstructive pulmonary disease and asthma are both obstructive airway diseases that involve chronic inflammation of the respiratory tract which contributes to disease progression. In the case of COPD, there is increasing evidence that lung macrophages orchestrate inflammation through the release of chemokines that attract neutrophils, monocytes and T cells and the release of several proteases. On the other hand, in asthma, it seems that alveolar macrophages are inappropriately activated and are implicated in the development and progression of the disease. In this review we summarize the current basic and clinical research studies which highlight the role of macrophages in asthma and COPD.

SIRT1 redresses the imbalance of tissue inhibitor of matrix metalloproteinase-1 and matrix metalloproteinase-9 in the development of mouse emphysema and human COPD

Sirtuin1 (SIRT1), a protein/histone deacetylase, protects against the development of pulmonary emphysema. However, the molecular mechanisms underlying this observation remain elusive. The imbalance of tissue inhibitor of matrix metalloproteinases (TIMPs)/matrix metalloproteinases (MMPs) plays an important role in the pathogenesis of chronic obstructive pulmonary disease (COPD)/emphysema. We hypothesized that SIRT1 protects against emphysema by redressing the imbalance between MMPs and TIMPs. To test this hypothesis, SIRT1-deficient and overexpressing/transgenic mice were exposed to cigarette smoke (CS). The protein level and activity of MMP-9 were increased in lungs of SIRT1-deficient mice exposed to CS compared with wild-type (WT) littermates, and these effects were attenuated by SIRT1 overexpression. SIRT1 deficiency decreased the level of TIMP-1, which was augmented in SIRT1 transgenic mice compared with WT littermates by CS. However, the level of MMP-2, MMP-12, TIMP-2, TIMP-3, or TIMP-4 was not altered by SIRT1 in response to CS exposure. SIRT1 reduction was associated with imbalance of TIMP-1 and MMP-9 in lungs of smokers and COPD patients. Mass spectrometry and immunoprecipitation analyses revealed that TIMP-1 acetylation on specific lysine residues was increased, whereas its interaction with SIRT1 and MMP-9 was reduced in mouse lungs with emphysema, as well as in lungs of smokers and COPD patients. SIRT1 deficiency increased CS-induced TIMP-1 acetylation, and these effects were attenuated by SIRT1 overexpression. These results suggest that SIRT1 protects against COPD/emphysema, in part, via redressing the TIMP-1/MMP-9 imbalance involving TIMP-1 deacetylation. Thus redressing the TIMP-1/MMP-9 imbalance by pharmacological activation of SIRT1 is an attractive approach in the intervention of COPD.

Chronic obstructive pulmonary disease and bronchiectasis

PURPOSE OF REVIEW

Chronic obstructive pulmonary disease (COPD) and bronchiectasis are two different but related diseases that occur separately, but can coexist. In this review, we will examine the recent research regarding patients with COPD who have coexisting bronchiectasis.

RECENT FINDINGS

Recent research has focused on defining distinct COPD phenotypes with the ultimate goal of changing the outcomes using tailored therapies. A frequent exacerbator phenotype has been identified. COPD patients with Pseudomonas aeruginosa are a phenotype with worse outcomes. Patients with coexisting COPD and bronchiectasis may represent a unique phenotype.

SUMMARY

Patients with coexisting COPD and bronchiectasis could represent a unique phenotype with more severe disease, worse outcomes, more isolation of potentially pathogenic microorganisms, and more frequent exacerbations, with the potential for targeted therapies.

Cardiovascular disease in COPD: mechanisms

It is now well established that cardiovascular disease contributes significantly to both morbidity and mortality in COPD. Shared risk factors for cardiovascular disease and COPD, such as smoking, low socioeconomic class, and a sedentary lifestyle contribute to the natural history of each of these conditions. However, it is now apparent that alternative, novel mechanisms are involved in the pathogenesis of cardiovascular disease, and these may play an important role in driving the increased cardiovascular risk associated with COPD. In this article, we discuss the potential mechanisms that link COPD to an increased risk of cardiovascular disease.

Association of genes of protease-antiprotease balance pathway to lung function and emphysema subtypes

Background

The imbalance between proteases and antiproteases has been proposed to participate to the pathogenesis of chronic obstructive pulmonary disease (COPD) and emphysema. Gene level variation in different metalloproteinases, metalloproteinase inhibitors, and cytokines affecting them may contribute to this imbalance and destruction of the lung parenchyma. We investigated whether polymorphisms in selected protease-antiprotease balance pathway genes predispose to different emphysema subtypes (centrilobular, paraseptal, panlobular, and bullae) and airflow limitation among Finnish construction workers.

Methods

Eleven single nucleotide polymorphisms (SNPs) from seven genes (GC: rs7041 and rs4588; MMP1: rs1799750; MMP9: rs3918242; MMP12: rs652438; TIMP2: rs2277698; TNF: rs1799724 and rs1800629; TGFB1: rs1800469, rs1800470, and rs2241718) were analyzed from 951 clinically and radiologically characterized construction workers. The genotype and haplotype data was compared to different emphysematous signs confirmed with high resolution computed tomography (HRCT), forced vital capacity (FVC), forced expiratory volume in one second (FEV₁), and maximal expiratory flow at 50% of FVC (MEF50) by using linear and logistic regression analyses, adjusted for potential confounders.

Results

The TIMP2 rs2277698 SNP was associated with overall (p = 0.022) and paraseptal (p = 0.010) emphysema, as well as with FEV₁/FVC ratio (p = 0.035) and MEF50 (p = 0.008). The TGFB1 rs2241718 and MMP9 rs3918242 SNPs were associated with centrilobular emphysema (p = 0.022 and p = 0.008), and the TNF rs1800629 SNP with paraseptal emphysema (p = 0.017). In stratified analysis, individuals with at least one TIMP2 rs2277698 or TNF rs1800629 variant allele were found to be at around two-fold risk for pathological paraseptal changes (OR 1.94, 95% CI 1.14-3.30; OR 2.10, 95% CI 1.24-3.56). On the contrary, the risk for pathological centrilobular changes was halved for individuals with at least one MMP9 rs3918242 (OR 0.51, 95% CI 0.30-0.86) or TGFB1 rs2241718 (OR 0.53, 95% CI 0.30-0.90) variant allele, or TGFB1 rs1800469-rs1800470 AT-haplotype (OR 0.55, 95% CI 0.33-0.93). MEF50, in turn, was significantly reduced among individuals with at least one TIMP2 rs2277698 variant allele (p = 0.011).

Conclusion

Our findings strengthen the hypothesis of the importance of protease-antiprotease balance in pathogenesis of emphysema and shed light on the aetiology of different emphysema subtypes by associating MMP9 and TGFB1 to centrilobular emphysema, and TIMP2 and TNF to paraseptal emphysema and/or airflow obstruction.

Matrix metalloproteinase-9 -1562C/T promoter polymorphism confers risk for COPD: a meta-analysis

BACKGROUND

The role of matrix metalloproteinase (MMP) gene polymorphisms in the development of chronic obstructive pulmonary disease (COPD) has been reported with inconsistent results. This meta-analysis was performed to assess the association of MMP-1 -1607G/GG and MMP-9 -1562C/T promoter polymorphisms with COPD susceptibility.

METHODS

Published case-control studies from Pubmed and China National Knowledge Infrastructure (CNKI) databases were retrieved. Data were extracted and pooled odds ratios (OR) with 95% confidence intervals (CI) were calculated.

RESULTS

A total of fourteen case-control studies were included in this meta-analysis. Pooled effect size showed an association of MMP-9 -1562 C/T with the risk of COPD (dominant model: TT+CT vs CC; OR: 1.46; 95% CI: 1.02-2.08; p = 0.04). However, no correlation with COPD was revealed in MMP-1 -1607G/GG polymorphism. When stratified by ethnicity, results indicated MMP-1 -1607G/GG (recessive model: G/G vs G/GG+GG/GG; OR: 1.20; 95% CI: 1.01-1.44; p = 0.04) and MMP-9 -1562 C/T (dominant model; OR: 1.66; 95% CI: 1.01-2.71; p = 0.04) were correlated with COPD susceptibility among Caucasians and Asians respectively. According to source of controls, significant association of MMP-9 -1562 C/T (additive model: T vs C; OR:1.71, 95% CI: 1.42-2.07; p<0.00001, and dominant model; OR: 1.92; 95% CI: 1.34-2.76; p = 0.0004) with COPD susceptibility was revealed in the subgroup with smoker-based controls. However, in the aforementioned risk estimates, only the association of MMP-9 -1562 C/T (additive and dominant models) with the risk of COPD in the subgroup with smoker-based controls persisted significantly after Bonferroni correction for multiple testing. Moreover, after excluding the studies without Hardy-Weinberg equilibrium and/or with small sample size, the pooled results were robust and no publication bias was found in this study.

CONCLUSION

This meta-analysis suggests, when using healthy smokers as controls, MMP-9 -1562 C/T, but not MMP-1 -1607 G/GG polymorphism is associated with the risk of COPD.

Increased matrix metalloproteinase (MMPs) levels do not predict disease severity or progression in emphysema

RATIONALE

Though matrix metalloproteinases (MMPs) are critical in the pathogenesis of COPD, their utility as a disease biomarker remains uncertain. This study aimed to determine whether bronchoalveolar lavage (BALF) or plasma MMP measurements correlated with disease severity or functional decline in emphysema.

METHODS

Enzyme-linked immunosorbent assay and luminex assays measured MMP-1, -9, -12 and tissue inhibitor of matrix metalloproteinase-1 in the BALF and plasma of non-smokers, smokers with normal lung function and moderate-to-severe emphysema subjects. In the cohort of 101 emphysema subjects correlative analyses were done to determine if MMP or TIMP-1 levels were associated with key disease parameters or change in lung function over an 18-month time period.

MAIN RESULTS

Compared to non-smoking controls, MMP and TIMP-1 BALF levels were significantly elevated in the emphysema cohort. Though MMP-1 was elevated in both the normal smoker and emphysema groups, collagenase activity was only increased in the emphysema subjects. In contrast to BALF, plasma MMP-9 and TIMP-1 levels were actually decreased in the emphysema cohort compared to the control groups. Both in the BALF and plasma, MMP and TIMP-1 measurements in the emphysema subjects did not correlate with important disease parameters and were not predictive of subsequent functional decline.

CONCLUSIONS

MMPs are altered in the BALF and plasma of emphysema; however, the changes in MMPs correlate poorly with parameters of disease intensity or progression. Though MMPs are pivotal in the pathogenesis of COPD, these findings suggest that measuring MMPs will have limited utility as a prognostic marker in this disease.

Updates on the COPD gene list

A genetic contribution to develop chronic obstructive pulmonary disease (COPD) is well established. However, the specific genes responsible for enhanced risk or host differences in susceptibility to smoke exposure remain poorly understood. The goal of this review is to provide a comprehensive literature overview on the genetics of COPD, highlight the most promising findings during the last few years, and ultimately provide an updated COPD gene list. Candidate gene studies on COPD and related phenotypes indexed in PubMed before January 5, 2012 are tabulated. An exhaustive list of publications for any given gene was looked for. This well-documented COPD candidate-gene list is expected to serve many purposes for future replication studies and meta-analyses as well as for reanalyzing collected genomic data in the field. In addition, this review summarizes recent genetic loci identified by genome-wide association studies on COPD, lung function, and related complications. Assembling resources, integrative genomic approaches, and large sample sizes of well-phenotyped subjects is part of the path forward to elucidate the genetic basis of this debilitating disease.

Recent findings in chronic obstructive pulmonary disease by using quantitative computed tomography

Chronic obstructive pulmonary disease (COPD) is characterized by an incompletely reversible airflow limitation that results from a combination of airway wall remodeling and emphysematous lung destruction. Forced expiratory volume in 1s (FEV(1)) has been considered the gold standard for diagnosis, classification, and follow-up in patients with COPD, but it has certain limitations and it is still necessary to find other noninvasive modalities to complement FEV(1) to evaluate the effect of therapeutic interventions and the pathogenesis of COPD. Quantitative computed tomography (CT) has partly met this demand. The extent of emphysema and airway dimensions measured using quantitative CT are associated with morphological and functional changes and clinical symptoms in patients with COPD. Phenotyping COPD based on quantitative CT has facilitated interventional and genotypic studies. Recent advances in COPD findings with quantitative CT are discussed in this review.