Systemic biomarkers of neutrophilic inflammation, tissue injury and repair in COPD patients with differing levels of disease severity

Evaluation of neutrophil gelatinase-associated lipocalin (NGAL), hypoxia-induced factor-1 alpha (HIF-1α) and apelin 13 levels as new potential biomarkers for pulmonary thromboembolism: A prospective clinical study

AIM

The objective was to evaluate the serum levels of neutrophil gelatinase-associated lipocalin (NGAL), hypoxia-induced factor-1 alpha (HIF-1α), and apelin 13 in patients with acute pulmonary thromboembolism (PE) and to investigate their diagnostic and prognostic role in PE patients with different mortality risk groups.

MATERIAL AND METHODS

This study was conducted in a tertiary referral center and included 124 subjects with 94 cases of PE and 30 cases of healthy control group. All subjects were 18 years of age or older. The diagnosis of PE was done with computed tomography angiography of the thorax. After the diagnosis of acute PE, the serum levels of neutrophil gelatinase-associated lipocalin (NGAL), hypoxia-induced factor-1 alpha (HIF-1α), and apelin 13 levels were measured with a commercial enzyme-linked immunosorbent assay (ELISA) kit.

RESULTS

The median and IQR (interquartile range) age of patients and control groups were 68 (56-76) and 61.5 (56-67) years, respectively. The majority of patients with PE had risk factors (97.88 %), and only two (2.12 %) had no known risk factors. HIF-1 alpha level was found to be higher in the patient group than in the control group (p = 0.03). At the same time, the HIF-1 alpha level was found to be higher in the high mortality risk group than in the control group, low mortality risk group and intermediate-low mortality risk group (p = 0.000, 0.011, 0.002, respectively). While there was no significant difference in NGAL level between the patient group and the control group, a significant difference was observed between the mortality groups. NGAL level was found to be higher in the high mortality risk group than the control group, low mortality risk group, and medium-low mortality risk group (p = 0.001, 0.000, 0.010, respectively). Apelin 13 levels did not differ significantly in all groups.

CONCLUSION

HIF-1 alpha is a promising biomarker in distinguishing between patients and control groups and in identifying those with high mortality risk in the patient group. At the same time, NGAL can be used as a successful biomarker in determining the group with high mortality risk in cases of PE.

The AGE-RAGE axis associates with chronic pulmonary diseases and smoking in the Rotterdam study

BACKGROUND

Chronic obstructive pulmonary disease (COPD) and asthma associate with high morbidity and mortality. High levels of advanced glycation end products (AGEs) were found in tissue and plasma of COPD patients but their role in COPD and asthma is unclear.

METHODS

In the Rotterdam Study (n = 2577), AGEs (by skin autofluorescence (SAF)), FEV1 and lung diffusing capacity (DLCOc and DLCOc /alveolar volume [VA]) were measured. Associations of SAF with asthma, COPD, GOLD stage, and lung function were analyzed using logistic and linear regression adjusted for covariates, followed by interaction and stratification analyses. sRAGE and EN-RAGE associations with COPD prevalence were analyzed by logistic regression.

RESULTS

SAF associated with COPD prevalence (OR = 1.299 [1.060, 1.591]) but not when adjusted for smoking (OR = 1.106 [0.89, 1.363]). SAF associated with FEV1% predicted (β=-3.384 [-4.877, -1.892]), DLCOc (β=-0.212 [-0.327, -0.097]) and GOLD stage (OR = 4.073, p = 0.001, stage 3&4 versus 1). Stratified, the association between SAF and FEV1%predicted was stronger in COPD (β=-6.362 [-9.055, -3.670]) than non-COPD (β=-1.712 [-3.306, -0.118]). Association of SAF with DLCOc and DLCOc/VA were confined to COPD (β=-0.550 [-0.909, -0.191]; β=-0.065 [-0.117, -0.014] respectively). SAF interacted with former smoking and COPD prevalence for associations with lung function. Lower sRAGE and higher EN-RAGE associated with COPD prevalence (OR = 0.575[0.354, 0.931]; OR = 1.778[1.142, 2.768], respectively).

CONCLUSIONS

Associations between SAF, lung function and COPD prevalence were strongly influenced by smoking. SAF associated with COPD severity and its association with lung function was more prominent within COPD. These results fuel further research into interrelations and causality between SAF, smoking and COPD.

TAKE-HOME MESSAGE

Skin AGEs associated with prevalence and severity of COPD and lung function in the general population with a stronger effect in COPD, calling for further research into interrelations and causality between SAF, smoking and COPD.

Functional Activity of Blood Neutrophils in Patients with Stable Course and Exacerbation of Chronic Obstructive Pulmonary Disease

We performed a comparative study of the parameters of chemiluminescence of blood neutrophils in patients with different severity of chronic obstructive pulmonary disease in its different periods. The maximum values of induced and spontaneous chemiluminescence were recorded at moderate severity of the disease during exacerbation. Low levels of chemiluminescence indicators were found in severe chronic obstructive pulmonary disease in the stable phase. The values of the induction period of the chemiluminescent response in patients with moderate chronic obstructive pulmonary disease were higher than in the control group. Correlations between the values of induced chemiluminescence of neutrophils and the respiration function parameter FEV1 were established, which may indicate the influence of multidirectional changes in the functional activity of systemic neutrophils on the development and worsening of airway obstruction in chronic obstructive pulmonary disease patients.

A blood and bronchoalveolar lavage protein signature of rapid FEV1 decline in smoking-associated COPD

Accelerated progression of chronic obstructive pulmonary disease (COPD) is associated with increased risks of hospitalization and death. Prognostic insights into mechanisms and markers of progression could facilitate development of disease-modifying therapies. Although individual biomarkers exhibit some predictive value, performance is modest and their univariate nature limits network-level insights. To overcome these limitations and gain insights into early pathways associated with rapid progression, we measured 1305 peripheral blood and 48 bronchoalveolar lavage proteins in individuals with COPD [n = 45, mean initial forced expiratory volume in one second (FEV1) 75.6 ± 17.4% predicted]. We applied a data-driven analysis pipeline, which enabled identification of protein signatures that predicted individuals at-risk for accelerated lung function decline (FEV1 decline ≥ 70 mL/year) ~ 6 years later, with high accuracy. Progression signatures suggested that early dysregulation in elements of the complement cascade is associated with accelerated decline. Our results propose potential biomarkers and early aberrant signaling mechanisms driving rapid progression in COPD.

The AGE-RAGE Axis and the Pathophysiology of Multimorbidity in COPD

Chronic obstructive pulmonary disease (COPD) is a disease of the airways and lungs due to an enhanced inflammatory response, commonly caused by cigarette smoking. Patients with COPD are often multimorbid, as they commonly suffer from multiple chronic (inflammatory) conditions. This intensifies the burden of individual diseases, negatively affects quality of life, and complicates disease management. COPD and comorbidities share genetic and lifestyle-related risk factors and pathobiological mechanisms, including chronic inflammation and oxidative stress. The receptor for advanced glycation end products (RAGE) is an important driver of chronic inflammation. Advanced glycation end products (AGEs) are RAGE ligands that accumulate due to aging, inflammation, oxidative stress, and carbohydrate metabolism. AGEs cause further inflammation and oxidative stress through RAGE, but also through RAGE-independent mechanisms. This review describes the complexity of RAGE signaling and the causes of AGE accumulation, followed by a comprehensive overview of alterations reported on AGEs and RAGE in COPD and in important co-morbidities. Furthermore, it describes the mechanisms by which AGEs and RAGE contribute to the pathophysiology of individual disease conditions and how they execute crosstalk between organ systems. A section on therapeutic strategies that target AGEs and RAGE and could alleviate patients from multimorbid conditions using single therapeutics concludes this review.

Significant Interrelations among Serum Annexin A1, Soluble Receptor for Advanced Glycation End Products (sRAGE) and rs2070600 in Chronic Obstructive Pulmonary Disease

Chronic obstructive pulmonary disease (COPD) is a major cause of death and morbidity; it may be accompanied by oxidative stress and inflammation with or without underlying genetic etiology. Finding circulating biomarkers for COPD that can help early diagnosis and predict exacerbation and association with respiratory functions has been challenging. There were 40 healthy participants and 60 COPD patients in this research. The rs2070600 gene variant was examined by PCR-RFLP. Circulating sRAGE and annexin A1 levels were determined by ELISA. GSH and MDA were determined by spectrophotometry. In COPD patients, sRAGE serum levels were substantially lower, but conversely, annexin A1 levels were much greater than in controls. The rs2070600 gene polymorphism's strong association with COPD was demonstrated by genotyping and allelic frequency distribution. The GA genotype was most distributed in COPD, and it was strongly linked to lower serum sRAGE levels. The interrelation between annexin A1, sRAGE, and COPD could be explained through effects on inflammatory mediators' pathways. The rs2070600 gene polymorphism was found to significantly enhance the risk of COPD. Serum sRAGE and annexin A1 may be considered potential diagnostic tools for COPD. Through impacts on GSH and MDA levels that alter the release of inflammatory factors and, therefore, lung damage, it is possible to explain the relationship between annexin A1, sRAGE, and COPD.

Role of RAGE and its ligand HMGB1 in the development of COPD

Smoking is a well-established risk factor for chronic obstructive pulmonary disease (COPD). Chronic lung inflammation continues even after smoking cessation and leads to COPD progression. To date, anti-inflammatory therapies are ineffective in improving pulmonary function and COPD symptoms, and new molecular targets are urgently needed to deal with this challenge. The receptor for advanced glycation end-products (RAGE) was shown to be relevant in COPD pathogenesis, since it is both a genetic determinant of low lung function and a determinant of COPD susceptibility. Moreover, RAGE is involved in the physiological response to cigarette smoke exposure. Since innate and acquired immunity plays an essential role in the development of chronic inflammation and emphysema in COPD, here we summarized the roles of RAGE and its ligand HMGB1 in COPD immunity.

Carbocysteine Modifies Circulating miR-21, IL-8, sRAGE, and fAGEs Levels in Mild Acute Exacerbated COPD Patients: A Pilot Study

Patients with Chronic Obstructive Pulmonary Disease (COPD) periodically experience acute exacerbation (AECOPD). Carbocysteine represents a valid add on therapy in COPD by exerting antioxidant and anti-inflammatory activities. The in vivo effects of carbocysteine on inflammatory markers are not yet fully understood. The aims of this study were to assess: (i) miR-21, IL-8, soluble Receptor for Advanced Glycation End Products (sRAGE), and fluorescent Advanced Glycation End Products (fAGEs) in control subjects (n = 9), stable (n = 9), and AECOPD patients (n = 24); and (ii) whether carbocysteine modifies these markers and the functional parameters in mild AECOPD patients. Mild AECOPD patients received or not carbocysteine along with background inhalation therapy for 20 days. At the onset and at the end of the observation period, the following parameters were evaluated: FEV1, FEF25–75%, CAT questionnaire; miR-21 by Real Time PCR; IL-8 and sRAGE by ELISA; and fAGEs by spectro-fluorescence method. COPD patients showed higher levels of miR-21, IL-8, fAGEs and lower levels of sRAGE compared to that of controls. miR-21 inversely correlated with FEV1. IL-8 and fAGEs were significantly different in stable and exacerbated COPD patients. Carbocysteine improved symptoms, FEV1 and FEF25–75%, increased sRAGE, and reduced miR-21, IL-8, and fAGEs in mild AECOPD patients. The present study provides compelling evidence that carbocysteine may help to manage mild AECOPD by downregulating some parameters of systemic inflammation.

Association between plasma sRAGE and emphysema according to the genotypes of AGER gene

Background

Higher soluble receptor for advanced glycation end product (sRAGE) levels are considered to be associated with severe emphysema. However, the relationship remains uncertain when the advanced glycation end-product specific receptor (AGER) gene is involved. We aimed to analyse the association between sRAGE levels and emphysema according to the genotypes of rs2070600 in the AGER gene.

Methods

We genotyped rs2070600 and measured the plasma concentration of sRAGE in each participant. Emphysema was quantified based on the chest computed tomography findings. We compared sRAGE levels based on the presence or absence and severity of emphysema in each genotype. Multiple logistic and linear regression models were used for the analyses.

Results

A total of 436 participants were included in the study. Among them, 64.2% had chronic obstructive pulmonary disease and 34.2% had emphysema. Among the CC-genotyped participants, the sRAGE level was significantly higher in participants without emphysema than in those with emphysema (P < 0.001). In addition, sRAGE levels were negatively correlated with emphysema severity in CC-genotyped patients (r = − 0.268 P < 0.001). Multiple regression analysis revealed that sRAGE was an independent protective factor for the presence of emphysema (adjusted odds ratio, 0.24; 95% confidence interval (CI) 0.11–0.51) and severity of emphysema (β = − 3.28, 95% CI − 4.86 to − 1.70) in CC-genotyped participants.

Conclusion

Plasma sRAGE might be a biomarker with a protective effect on emphysema among CC-genotyped patients of rs2070600 on the AGER gene. This is important in determining the target group for the future prediction and treatment of emphysema.

Supplementary Information

The online version contains supplementary material available at 10.1186/s12890-022-01848-9.

Plasma sRAGE levels strongly associate with centrilobular emphysema assessed by HRCT scans

Background

There is a strong need for biomarkers to better characterize individuals with COPD and to take into account the heterogeneity of COPD. The blood protein sRAGE has been put forward as promising biomarker for COPD in general and emphysema in particular. Here, we measured plasma sRAGE levels using quantitative LC–MS and assessed whether the plasma sRAGE levels associate with (changes in) lung function, radiological emphysema parameters, and radiological subtypes of emphysema.

Methods

Three hundred and twenty-four COPD patients (mean FEV₁: 63%predicted) and 185 healthy controls from the COPDGene study were selected. Plasma sRAGE was measured by immunoprecipitation in 96-well plate methodology to enrich sRAGE, followed by targeted quantitative liquid chromatography-mass spectrometry. Spirometry and HRCT scans (inspiration and expiration) with a 5-year follow-up were used; both subjected to high quality control standards.

Results

Lower sRAGE values significantly associated with the presence of COPD, the severity of airflow obstruction, the severity of emphysema on HRCT, the heterogeneous distribution of emphysema, centrilobular emphysema, and 5-year progression of emphysema. However, sRAGE values did not associate with airway wall thickness or paraseptal emphysema.

Conclusions

Rather than being a general COPD biomarker, sRAGE is especially a promising biomarker for centrilobular emphysema. Follow-up studies should elucidate whether sRAGE can be used as a biomarker for other COPD phenotypes as well.

Evaluation of the prognostic value of neutrophil-to-lymphocyte ratio and platelet-to-lymphocyte ratio in acute exacerbation of chronic obstructive pulmonary disease

Background:

The present study aimed at determining and comparing the prognostic value and the relationship of neutrophil-to-lymphocyte and platelet-to-lymphocyte ratios (PLRs) with acute exacerbation of chronic obstructive pulmonary disease (AECOPD).

Materials and Methods:

The present case–control study was performed on 100 chronic obstructive pulmonary disease patients and 100 healthy subjects (controls). Age, gender, and laboratory results of complete blood count tests including lymphocyte count, neutrophil count, platelet count, hemoglobin level, neutrophil-to-lymphocyte ratio (NLR), PLR, C-reactive protein (CRP), and erythrocyte sedimentation rate (ESR) were obtained from the patient report and then recorded. The mentioned information was also completed for the control group. Following hospitalization, the patients that were discharged with clinically stable general status were re-examined, and the aforementioned laboratory information was rerecorded.

Results:

The results of the present study revealed that NLR with the sensitivity and specificity of 83.00% (74.2%–89.8%) and 93.00% (86.1%–97.1%) (cutoff value of 2.3), PLR with the sensitivity and specificity of 56.00% (46.0%–66.3%) and 83.00% (74.2%–89.8%) (cutoff value of 135.8), white blood cell (WBC) with the sensitivity and specificity of 69.00% (57.7%–77.8%) and 78.00% (68.6%–85.7%) (cutoff value of 8.5 × 103 μl), ESR with the sensitivity and specificity of 84.00% (75.3%–90.6%) and 99.00% (94.6%–100.0%) (cutoff value of 7.8), and CRP with the sensitivity and specificity of 52.00% (41.8%–62.1%) and 81.00% (71.9%–88.2%) (cutoff value of 1.9), respectively, had a significant prognostic value of AECOPD (P < 0.001). In addition to NLR had higher area under the curve (AUC) than PLR, WBC, and CRP. Therefore NLR had a better diagnostic value than the above three markers (P < 0.001). ESR also has higher AUC levels compared to PLR, WBC, and CRP and has a statistically better diagnostic value than them (P < 0.001), but did not differ significantly from ESR (difference between AUC: 0.02; P = 0.059).

Conclusion:

According to the results of the current study, NLR and PLR had a significant direct relationship with the two main markers of ESR and CRP, and both ratios had a significant prognostic value in AECOPD.

Lung proteomic biomarkers associated with chronic obstructive pulmonary disease

Identifying protein biomarkers for chronic obstructive pulmonary disease (COPD) has been challenging. Most previous studies have used individual proteins or preselected protein panels measured in blood samples. Mass spectrometry proteomic studies of lung tissue have been based on small sample sizes. We used mass spectrometry proteomic approaches to discover protein biomarkers from 150 lung tissue samples representing COPD cases and controls. Top COPD-associated proteins were identified based on multiple linear regression analysis with false discovery rate (FDR) < 0.05. Correlations between pairs of COPD-associated proteins were examined. Machine learning models were also evaluated to identify potential combinations of protein biomarkers related to COPD. We identified 4,407 proteins passing quality controls. Twenty-five proteins were significantly associated with COPD at FDR < 0.05, including interleukin 33, ferritin (light chain and heavy chain), and two proteins related to caveolae (CAV1 and CAVIN1). Multiple previously reported plasma protein biomarkers for COPD were not significantly associated with proteomic analysis of COPD in lung tissue, although RAGE was borderline significant. Eleven pairs of top significant proteins were highly correlated (r > 0.8), including several strongly correlated with RAGE (EHD2 and CAVIN1). Machine learning models using Random Forests with the top 5% of protein biomarkers demonstrated reasonable accuracy (0.707) and area under the curve (0.714) for COPD prediction. Mass spectrometry-based proteomic analysis of lung tissue is a promising approach for the identification of biomarkers for COPD.

Neutrophil-Dependent Immunity During Pulmonary Infections and Inflammations

Rapid recruitment of neutrophils to an inflamed site is one of the hallmarks of an effective host defense mechanism. The main pathway through which this happens is by the innate immune response. Neutrophils, which play an important part in innate immune defense, migrate into lungs through the modulation actions of chemokines to execute a variety of pro-inflammatory functions. Despite the importance of chemokines in host immunity, little has been discussed on their roles in host immunity. A holistic understanding of neutrophil recruitment, pattern recognition pathways, the roles of chemokines and the pathophysiological roles of neutrophils in host immunity may allow for new approaches in the treatment of infectious and inflammatory disease of the lung. Herein, this review aims at highlighting some of the developments in lung neutrophil-immunity by focusing on the functions and roles of CXC/CC chemokines and pattern recognition receptors in neutrophil immunity during pulmonary inflammations. The pathophysiological roles of neutrophils in COVID-19 and thromboembolism have also been summarized. We finally summarized various neutrophil biomarkers that can be utilized as prognostic molecules in pulmonary inflammations and discussed various neutrophil-targeted therapies for neutrophil-driven pulmonary inflammatory diseases.

Implication of RAGE Polymorphic Variants in COPD Complication and Anti-COPD Therapeutic Potential of sRAGE

Chronic obstructive pulmonary disease (COPD) is a slowly progressive and poorly reversible airway obstruction disease. It is caused either alone or in combination of emphysema, chronic bronchitis (CB), and small airways disease. COPD is thought to be a multi-factorial disorder in which genetic susceptibility, environmental factors and tobacco exposure could be doubly or simultaneously implicated. Available medicines against COPD include anti-inflammatory drugs, such as β2-agonists and anticholinergics, which efficiently reduce airflow limitation but are unable to avert disease progression and mortality. Advanced glycation end products (AGE) and their receptors i.e. receptor for advanced glycation end products (RAGE) are some molecules that have been implicated in the complication of COPD. Several RAGE single nucleotide polymorphic (SNP) variants are produced by the mammalian cells. Based on the ethnicity some SNPs aggravate the COPD severity. Mammalian cells produce several alternative RAGE splice variants including a soluble RAGE (sRAGE) and an endogenous soluble RAGE (esRAGE). Both of these act as decoy receptor and thus may help to arrest the COPD complications. Several lines of evidences indicate a decreased level of sRAGE in the COPD subjects. One of the new strategies to reduce COPD complication may be sRAGE therapeutic administration to the COPD subjects. This comprehensive discussion sheds light on the role of RAGE and its polymorphic variants in the COPD complication along with sRAGE therapeutic significance in the COPD prevention.

Serum Neutrophil Gelatinase-associated Lipocalin (NGAL) Is Elevated in Patients with Asthma and Airway Obstruction

Neutrophilic airway inflammation is one of the features of severe asthma. Neutrophil gelatinase-associated lipocalin (NGAL), or lipocalin-2, is a glycoprotein associated with neutrophilic inflammation and can be detected in blood. Recently, blood NGAL levels have been reported to be elevated in chronic obstructive pulmonary disease. However, the clinical significance of serum NGAL levels in patients with asthma has not been elucidated. The aim of this study was to explore the association between serum NGAL level and clinical parameters in patients with asthma. Sixty-one non-smoking people with stable asthma were enrolled in this study. All patients underwent blood collection and pulmonary function tests. The associations between serum NGAL levels and clinical parameters were analyzed retrospectively. Serum NGAL levels in patients with asthma and obstructive ventilatory defect were higher than those in patients with asthma without obstructive ventilatory defect (76.4±51.4 ng/mL vs. 39.3±27.4 ng/mL, P=0.0019). Serum NGAL levels were correlated with forced expired flow at 50% of vital capacity %predicted and forced expired flow at 75% of vital capacity %predicted (r=-0.3373, P=0.0078 and r=-0.2900, P=0.0234, respectively). Results of a multiple regression analysis demonstrated that serum NGAL level was independently associated with obstructive ventilatory defect. Serum NGAL levels were elevated in patients with asthma and obstructive ventilatory defect. NGAL may be involved in airway remodeling possibly mediated by neutrophilic inflammation in asthma.

Fibrinogen is a promising biomarker for chronic obstructive pulmonary disease: evidence from a meta-analysis

Backgrounds: Some studies have reported association of circulating fibrinogen with the risk of chronic obstructive pulmonary disease (COPD), and the results are conflicting. To yield more information, we aimed to test the hypothesis that circulating fibrinogen is a promising biomarker for COPD by a meta-analysis.

Methods: Data extraction and quality assessment were independently completed by two authors. Effect-size estimates are expressed as weighted mean difference (WMD) with 95% confidence interval (95% CI).

Results: Forty-five articles involving 5586/18604 COPD patients/controls were incorporated. Overall analyses revealed significantly higher concentrations of circulating fibrinogen in COPD patients than in controls (WMD: 84.67 mg/dl; 95% CI: 64.24–105.10). Subgroup analyses by COPD course showed that the degree of increased circulating fibrinogen in patients with acute exacerbations of COPD (AECOPD) relative to controls (WMD: 182.59 mg/dl; 95% CI: 115.93–249.25) tripled when compared in patients with stable COPD (WMD: 56.12 mg/dl; 95% CI: 34.56–77.67). By COPD severity, there was a graded increase in fibrinogen with the increased severity of COPD relative to controls (Global Initiative for Obstructive Lung Disease (GOLD) I, II, III, and IV: WMD: 13.91, 29.19, 56.81, and 197.42 mg/dl; 95% CI: 7.70–20.11, 17.43–40.94, 39.20–74.41, and −7.88 to 402.73, respectively). There was a low probability of publication bias.

Conclusion: Our findings indicate a graded, concentration-dependent, significant relation between higher circulating fibrinogen and more severity of COPD.

Diffusing capacity in chronic obstructive pulmonary disease assessment: A meta-analysis

To achieve a multidimensional evaluation of chronic obstructive pulmonary disease (COPD) patients, the spirometry measures are supplemented by assessment of symptoms, risk of exacerbations, and CT imaging. However, the measurement of diffusing capacity of the lung for carbon monoxide (DLCO) is not included in most common used models of COPD assessment. Here, we conducted a meta-analysis to evaluate the role of DLCO in COPD assessment.The studies were identified by searching the terms "diffusing capacity" OR "diffusing capacity for carbon monoxide" or "DLCO" AND "COPD" AND "assessment" in Pubmed, Cochrane Central Register of Controlled Trials (CENTRAL), MEDLINE, Embase, Scopus, and Web of Science databases. The mean difference of DLCO % predict was assessed in COPD patient with different severity (according to GOLD stage and GOLD group), between COPD patients with or without with frequent exacerbation, between survivors and non-survivors, between emphysema dominant and non-emphysema dominant COPD patients, and between COPD patients with or without pulmonary hypertension.43 studies were included in the meta-analysis. DLCO % predicted was significantly lower in COPD patients with more severe airflow limitation (stage II/IV), more symptoms (group B/D), and high exacerbation risk (group C/D). Lower DLCO % predicted was also found in exacerbation patients and non-survivors. Low DLCO % predicted was related to emphysema dominant phenotype, and COPD patients with PH.The current meta-analysis suggested that DLCO % predicted might be an important measurement for COPD patients in terms of severity, exacerbation risk, mortality, emphysema domination, and presence of pulmonary hypertension. As diffusion capacity reflects pulmonary ventilation and perfusion at the same time, the predictive value of DLCO or DLCO combined with other criteria worth further exploration.

Blood neutrophil counts are associated with exacerbation frequency and mortality in COPD

BACKGROUND

Identifying patients with COPD at increased risk of poor outcomes is challenging due to disease heterogeneity. Potential biomarkers need to be readily available in real-life clinical practice. Blood eosinophil counts are widely studied but few studies have examined the prognostic value of blood neutrophil counts (BNC).

METHODS

In a large population-based COPD registry in the East of Scotland (TARDIS: Tayside Allergic and Respiratory Disease Information System), BNC were compared to measures of disease severity and mortality for up to 15 years follow-up. Potential mechanisms of disease modification by BNC were explored in a nested microbiome substudy.

RESULTS

178,120 neutrophil counts were obtained from 7220 people (mean follow up 9 years) during stable disease periods. Median BNC was 5200cells/μL (IQR 4000-7000cells/μL). Mortality rates among the 34% of patients with elevated BNCs (defined as 6000-15000cells/μL) at the study start were 80% higher (14.0/100 person years v 7.8/100py, P < 0.001) than those with BNC in the normal range (2000-6000cells/μL). People with elevated BNC were more likely to be classified as GOLD D (46% v 33% P < 0.001), have more exacerbations (mean 2.3 v 1.3/year, P < 0.001), and were more likely to have severe exacerbations (13% vs. 5%, P < 0.001) in the following year. Eosinophil counts were much less predictive of these outcomes. In a sub-cohort (N = 276), patients with elevated BNC had increased relative abundance of Proteobacteria and reduced microbiome diversity.

CONCLUSION

High BNC may provide a useful indicator of risk of exacerbations and mortality in COPD patients.

Measures of lung function and their relationship with advanced glycation end-products

BACKGROUND

Advanced glycation end-products (AGEs) have been implicated in the pathophysiology of chronic obstructive pulmonary disease (COPD). However, the association between AGE accumulation in the skin measured by skin autofluorescence (SAF) and lung function in healthy subjects has not been explored in detail. We use a population-based study of 50-64-year-olds to assess spirometry, diffusing capacity of the lung for carbon monoxide (D LCO) and impulse oscillometry (IOS) in relation to SAF.

METHODS

Participants with information on SAF, lung function and potential confounding variables were included from the Swedish Cardiopulmonary Bioimage Study (SCAPIS) cohort (spirometry, n=4111; D LCO, n=3889; IOS, n=3970). Linear regression was used to assess changes in lung function (as measured by spirometry (forced expiratory volume in 1 s (FEV1), forced vital capacity (FVC) and FEV1/FVC), D LCO and IOS (resistance measured at 5 (R 5) and 20 Hz (R 20), R 5-R 20, area of reactance, reactance measured at 5 Hz (X- 5), and resonant frequency)) by a 1-sd increase in SAF.

RESULTS

FEV1, FVC and D LCO were significantly and inversely associated with SAF after adjustment for potential confounding factors (per 1-sd increase in SAF: FEV1 -0.03 L (95% CI -0.04- -0.02 L), p<0.001; FVC -0.03 L (95% CI -0.05- -0.02 L), p<0.001; D LCO -0.07 mmol·min-1·kPa-1 (95% CI -0.11- -0.03 mmol·min-1·kPa-1), p<0.001). This association was also found in nonsmokers and in non-COPD subjects. Pulmonary reactance (X 5) but not pulmonary resistance (R 5, R 20 and R 5-R 20) was significantly associated with SAF (per 1-sd increase in SAF: X 5 -0.001 kPa·L-1·s (95% CI -0.003-0.00 kPa·L-1·s), p=0.042), which was mirrored in non-COPD patients but not in current nonsmokers.

CONCLUSIONS

AGE accumulation, as measured by SAF, is significantly associated with lung function decrements indicative of changes in the lung parenchyma.

Increased von Willebrand Factor Processing in COPD, Reflecting Lung Epithelium Damage, Is Associated with Emphysema, Exacerbations and Elevated Mortality Risk

Background

Chronic obstructive pulmonary disease (COPD) is characterized by chronic inflammation and lung tissue deterioration. Given the high vascularity of the lung, von Willebrand factor (VWF), a central component of wound healing initiation, has previously been assessed in COPD. VWF processing, which is crucial for regulating the primary response of wound healing, has not been assessed directly. Therefore, this study aimed to characterize wound healing initiation in COPD using dynamic VWF-processing biomarkers and to evaluate how these relate to disease severity and mortality.

Methods

A cross-sectional analysis of plasma samples from the ECLIPSE study collected at year 1 from moderate to very severe COPD subjects (GOLD 2-4, n=984) was performed. We applied competitive neo-epitope ELISAs specifically targeting the formation of and ADAMTS13-processed form of VWF, VWF-N and VWF-A, respectively.

Results

VWF-A and VWF-N were significantly increased (VWF-N, p=0.01; VWF-A, p=0.0001) in plasma of symptomatic (mMRC score ≥2) compared to asymptomatic/mild symptomatic COPD subjects. Increased VWF-N and VWF-A levels were specifically associated with emphysema (VWF-N, p<0.0001) or prior exacerbations (VWF-A, p=0.01). When dichotomized, high levels of both biomarkers were associated with increased risk of all-cause mortality (VWF-N, HR 3.5; VWF-A, HR 2.64).

Conclusion

We demonstrate that changes in VWF processing were related to different pathophysiological aspects of COPD. VWF-N relates to the chronic condition of emphysema, while VWF-A was associated with the more acute events of exacerbations. This study indicates that VWF-A and VWF-N may be relevant markers for characterization of disease phenotype and are associated with mortality in COPD.

Study Identifier

NCT00292552; GSK study code SCO104960.

Machine Learning Approach for Predicting Past Environmental Exposures From Molecular Profiling of Post-Exposure Human Serum Samples

OBJECTIVE

To develop an approach for a retrospective analysis of post-exposure serum samples using diverse molecular profiles.

METHODS

The 236 molecular profiles from 800 de-identified human serum samples from the Department of Defense Serum Repository were classified as smokers or non-smokers based on direct measurement of serum cotinine levels. A machine-learning pipeline was used to classify smokers and non-smokers from their molecular profiles.

RESULTS

The refined supervised support vector machines with recursive feature elimination predicted smokers and non-smokers with 78% accuracy on the independent held-out set. Several of the identified classifiers of smoking status have previously been reported and four additional miRNAs were validated with experimental tobacco smoke exposure in mice, supporting the computational approach.

CONCLUSIONS

We developed and validated a pipeline that shows retrospective analysis of post-exposure serum samples can identify environmental exposures.

The Gene Expression Biomarkers for Chronic Obstructive Pulmonary Disease and Interstitial Lung Disease

COPD (chronic obstructive pulmonary disease) and ILD (interstitial lung disease) are two common respiratory diseases. They share similar clinical traits but require different therapeutic treatments. Identifying the biomarkers that are differentially expressed between them will not only help the diagnosis of COPD and ILD, but also provide candidate drug targets that may facilitate the development of new treatment for COPD and ILD. Due to the irreversible complex pathological changes of COPD, there are very limited therapeutic options for COPD patients. In this study, we analyzed the gene expression profiles of two datasets: one training dataset that includes 144 COPD patients and 194 ILD patients, and one test dataset that includes 75 COPD patients and 61 ILD patients. Advanced feature selection methods, mRMR (minimal Redundancy Maximal Relevance) and incremental feature selection (IFS), were applied to identify the 38-gene biomarker. An SVM (support vector machine) classifier was built based on the 38-gene biomarker. Its accuracy, sensitivity, and specificity on training dataset evaluated by leave one out cross-validation were 0.905, 0.896, and 0.912, respectively. And on independent test dataset, the accuracy, sensitivity, and specificity on were as great as and were 0.904, 0.933, and 0.869, respectively. The biological function analysis of the 38 genes indicated that many of them can be potential treatment targets that may benefit COPD and ILD patients.

S100A12 inhibits fibroblast migration via the receptor for advanced glycation end products and p38 MAPK signaling

The migration of lung fibroblasts plays a pivotal role in wound repair and fibrotic processes in the lung. Although the receptor for advanced glycation end products (RAGE) has been implicated in the pathogenesis of lung diseases, its role in lung fibroblast migration is unclear. The current study examined the effect of three different RAGE ligands, namely, high mobility group box 1 (HMGB1), S100A12, and N-epsilon-(carboxymethyl) lysine (CML), on human fibronectin-directed human fetal lung fibroblast (HFL-1) migration. HMGB1 augmented, whereas S100A12 inhibited, HFL-1 migration in a concentration-dependent manner. CML did not affect HFL-1 migration. The effect of HMGB1 was not through RAGE. However, the effect of S100A12 was mediated by RAGE, but not Toll-like receptor 4. S100A12 did not exert a chemoattractant effect, but inhibited HFL-1 chemotaxis and/or chemokinesis. Moreover, S100A12 mediated HFL-1 migration through p38 mitogen-activated protein kinase (MAPK) but not through nuclear factor-kappa B, protein kinase A, phosphatase and tensin homolog deleted on chromosome 10, or cyclooxygenase. In addition, western blot analysis showed that S100A12 augmented p38 MAPK activity in the presence of human fibronectin. In conclusion, S100A12 inhibits lung fibroblast migration via RAGE-p38 MAPK signaling. This pathway could represent a therapeutic target for pulmonary conditions characterized by abnormal tissue repair and remodeling.

Receptor for advanced glycation end-products and environmental exposure related obstructive airways disease: a systematic review

Background

Our group has identified the receptor for advanced glycation end-products (RAGE) as a predictor of World Trade Center particulate matter associated lung injury. The aim of this systematic review is to assess the relationship between RAGE and obstructive airways disease secondary to environmental exposure.

Methods

A comprehensive search using PubMed and Embase was performed on January 5, 2018 utilising keywords focusing on environmental exposure, obstructive airways disease and RAGE and was registered with PROSPERO (CRD42018093834). We included original human research studies in English, focusing on pulmonary end-points associated with RAGE and environmental exposure.

Results

A total of 213 studies were identified by the initial search. After removing the duplicates and applying inclusion and exclusion criteria, we screened the titles and abstracts of 61 studies. Finally, 19 full-text articles were included. The exposures discussed in these articles include particulate matter (n=2) and cigarette smoke (n=17).

Conclusion

RAGE is a mediator of inflammation associated end-organ dysfunction such as obstructive airways disease. Soluble RAGE, a decoy receptor, may have a protective effect in some pulmonary processes. Overall, RAGE is biologically relevant in environmental exposure associated lung disease. Future investigations should focus on further understanding the role and therapeutic potential of RAGE in particulate matter exposure associated lung disease.

RAGE is biologically relevant in environmental exposure associated lung disease. Future investigations should focus on further understanding the role and therapeutic potential of RAGE in particulate matter exposure associated lung diseasehttp://ow.ly/gfZz30o7otU

Smoking-induced iron dysregulation in the lung

Iron is one of the most abundant transition elements and is indispensable for almost all organisms. While the ability of iron to participate in redox chemistry is an essential requirement for participation in a range of vital enzymatic reactions, this same feature of iron also makes it dangerous in the generation of hydroxyl radicals and superoxide anions. Given the high local oxygen tensions in the lung, the regulation of iron acquisition, utilization, and storage therefore becomes vitally important, perhaps more so than in any other biological system. Iron plays a critical role in the biology of essentially every cell type in the lung, and in particular, changes in iron levels have important ramifications on immune function and the local lung microenvironment. There is substantial evidence that cigarette smoke causes iron dysregulation, with the implication that iron may be the link between smoking and smoking-related lung diseases. A better understanding of the connection between cigarette smoke, iron, and respiratory diseases will help to elucidate pathogenic mechanisms and aid in the identification of novel therapeutic targets.

Independent Prognostic Value of Pulmonary Diffusing Capacity in Nonsmoking Patients with Chronic Heart Failure

The diffusing capacity of the lung for carbon monoxide (DLCO) is indicative of the alveolar-capillary membrane function. A reduced DLCO is associated with poor prognosis in chronic heart failure (HF). However, the significance of DLCO as an independent prognostic predictor has not been established. Here, we aimed to determine the prognostic value of DLCO in patients with chronic HF.We enrolled 214 patients (139 females, mean age: 63 ± 16 years, left ventricular ejection fraction [LVEF]: 45 ± 21%) with stable chronic HF who underwent pulmonary function tests. Only never smokers were included in the analysis because smoking can decrease DLCO.During a median follow-up period of 2.1 years, 52 patients (24.3%) experienced cardiac events, including unplanned HF admissions, left ventricular assist device (LVAD) implantations, all-cause deaths, and cardiopulmonary arrests (CPAs). The median percent predicted DLCO (%DLCO) was 87.3%. In a Cox regression analysis, a %DLCO of ≤87.3% was independently associated with the cardiac events, even after adjusting for age, sex, systolic blood pressure (SBP), LVEF, anemia, brain natriuretic peptide, estimated glomerular filtration rate (eGFR), and prior HF admission (hazard ratio [HR]: 1.87, 95% confidence interval: 1.03-3.53, P = 0.030).A reduced DLCO is an independent predictor of poor prognosis in nonsmoking patients with chronic HF.

Heparin-binding EGF-like growth factor attenuates lung inflammation and injury in a murine model of pulmonary emphysema

Pulmonary inflammation and progressive lung destruction are the major causes of chronic obstructive pulmonary disease (COPD), resulting in emphysema and irreversible pulmonary dysfunction. Heparin-binding EGF-like growth factor (HB-EGF), is known to play a protective role in the process of various inflammatory diseases. However, its effect on COPD is poorly understood. This study was designed to determine the effect of HB-EGF on lung inflammation and injury in a murine model of pulmonary emphysema. HB-EGF promoted percent survival and body weight, attenuated lung injury, inflammatory cells, and cytokines infiltration, and prevented lung function decline. Additionally, treatment of rHB-EGF suppressed the nuclear translocation of nuclear factor κB (NF-κB)/p65, decreased TUNEL-positive cells and the expression of caspase 3, and increased the expression of PCNA, HB-EGF, and EGF receptor (EGFR). We conclude that HB-EGF attenuates lung inflammation and injury, probably through the activation of EGFR, followed by suppression of NF-ΚB signalling, promotion of cell proliferation, and inhibition of apoptosis.

Blood MCP-1 levels are increased in chronic obstructive pulmonary disease patients with prevalent emphysema

Background and aims

Chronic obstructive pulmonary disease (COPD) is a heterogeneous disease characterized by different phenotypes with either bronchial airways alterations or emphysema prevailing. As blood biomarkers could be clinically useful for COPD stratification, we aimed at investigating the levels of blood biomarkers in COPD patients differentiated by phenotype: prevalent chronic airway disease versus emphysema.

Methods

In 23 COPD patients with prevalent airway disease (COPD-B), 22 COPD patients with prevalent emphysema (COPD-E), 9 control smokers (CSs), and 18 control nonsmokers (CNSs), we analyzed the expression levels of interleukin (IL)-1α, IL-1β, IL-2, IL-4, IL-6, IL-8, IL-10, tumor necrosis factor (TNF)-α, interferon (IFN)-γ, epidermal growth factor (EGF), monocyte chemotactic protein (MCP)-1, and vascular endothelial growth factor by enzyme-linked immunosorbent assay in plasma/serum; glutathione peroxidase and superoxide dismutase (SOD)-1 by immunochemical kits in plasma; and free F2-isoprostanes (F2-IsoPs) by gas chromatography in plasma.

Results

F2-IsoPs level was increased in COPD-B and COPD-E compared with CSs and CNSs; in addition, CS showed higher levels than CNSs; SOD1 level was lower in COPD-B and COPD-E than that in CNSs. Interestingly, MCP-1 level was higher only in COPD-E versus CSs and CNSs; EGF and IL-8 levels were higher in COPD-B and COPD-E versus CNSs; IL-6 level was increased in all three smoking groups (COPD-B, COPD-E, and CSs) versus CNS; IFN-γ and IL-1α levels were higher in CSs than in CNSs; and IL-1α level was also higher in CSs versus COPD-B and COPD-E. In all subjects, F2-IsoPs level correlated positively and significantly with MCP-1, IL-2, IL-1β, IFN-γ, and TNF-α and negatively with SOD1. When correlations were restricted to COPD-E and COPD-B groups, F2-IsoPs maintained the positive associations with IFN-γ, TNF-α, and IL-2.

Conclusion

We did not find any specific blood biomarkers that could differentiate COPD patients with prevalent airway disease from those with prevalent emphysema. The MCP-1 increase in COPD-E, associated with the imbalance of oxidant/antioxidant markers, may play a role in inducing emphysema.

Granulocyte-CSF links destructive inflammation and comorbidities in obstructive lung disease

Chronic obstructive pulmonary disease (COPD) is an incurable inflammatory lung disease that afflicts millions of people worldwide, and it is the fourth leading cause of death. Systemic comorbidities affecting the heart, skeletal muscle, bone, and metabolism are major contributors to morbidity and mortality. Given the surprising finding in large prospective clinical biomarker studies that peripheral white blood cell count is more closely associated with disease than inflammatory biomarkers, we probed the role of blood growth factors. Using the SHIP-1-deficient COPD mouse model, which manifests a syndrome of destructive lung disease and a complex of comorbid pathologies, we have identified a critical and unexpected role for granulocyte-CSF (G-CSF) in linking these conditions. Deletion of G-CSF greatly reduced airway inflammation and lung tissue destruction, and attenuated systemic inflammation, right heart hypertrophy, loss of fat reserves, and bone osteoporosis. In human clinical translational studies, bronchoalveolar lavage fluid of patients with COPD demonstrated elevated G-CSF levels. These studies suggest that G-CSF may play a central and unforeseen pathogenic role in COPD and its complex comorbidities, and identify G-CSF and its regulators as potential therapeutic targets.

S100A12 as a marker of worse cardiac output and mortality in pulmonary hypertension

BACKGROUND AND OBJECTIVE

Molecular biomarkers are needed to refine prognostication and phenotyping of pulmonary hypertension (PH) patients. S100A12 is an emerging biomarker of various inflammatory diseases. This study aims to determine the prognostic value of S100A12 in PH.

METHODS

Exploratory microarray analysis performed on peripheral blood mononuclear cells (PBMC) collected from idiopathic pulmonary fibrosis (IPF) patients suggested an association between S100A12 and both PH and mortality. So the current study was designed to evaluate for an association between S100A12 in peripheral blood collected from two well-phenotyped PH cohorts in two other centres to derive and validate an association between S100A12 protein serum concentrations and mortality.

RESULTS

The majority of the patients in the discovery and validation cohorts were either World Health Organization (WHO) group 1 (pulmonary arterial hypertension (PAH)) or 3 (lung disease-associated) PH. In the discovery PH cohort, S100A12 was significantly increased in patients with PH (n = 51) compared to controls (n = 22) (29.8 vs 15.7 ng/mL, P < 0.001) and negatively correlated with cardiac output (r = -0.58, P < 0.001) in PH patients. When S100A12 data were pooled from both cohorts, PAH and non-PAH PH patients had higher S100A12 compared to healthy external controls (32.6, 30.9, 15.7 ng/mL; P < 0.001). S100A12 was associated with an increased risk in overall mortality in PH patients in both the discovery (n = 51; P = 0.008) and validation (n = 40; P < 0.001) cohorts.

CONCLUSION

S100A12 levels are increased in PH patients and are associated with increased mortality.

Severity of COPD and its relationship with IL-10

BACKGROUND

The present study was designed to compare inflammatory and metabolic responses according to severity of airflow among patients with COPD and to verify the relationship between pulmonary function, body composition, metabolic and inflammatory profile.

METHODS

Fifty-one patients with mild to very severe COPD were recruited and divided according lung function in Mild-moderate (GOLD 1-2) n= 21; Severe (GOLD 3) n=25 and Very severe (GOLD 4) n=5. Patients were submitted to assessments of lung function (spirometry), functional exercise capacity (6-min walk test), body composition (Octopolar bioelectrical impedance), metabolic profile (glucose, triglycerides, total cholesterol, HDL-cholesterol and albumin (colorimetric assay)) and inflammatory profile (cytokines: IL-6, IL-10, TNF-α and IL-15 (ELISA)).

RESULTS

We found that patients in GOLD 3 group had lower levels of IL-10, triglycerides, visceral fat area, and higher IL-6 and IL-6/IL-10 ratio when compared to GOLD 1-2 patients. Additionally, GOLD 1-2 group presented negative correlation between TNF-α and HDL cholesterol (p= .01) and positive correlation between IL-15 and FEV₁/FVC (p=.01), while GOLD 3 group showed positive correlation between IL-6 and IL-10 (p< .01), IL-6 and total cholesterol (p<.01) and negative correlation between IL-10 and HDL-cholesterol (p=.01).

CONCLUSION

Our findings suggest that patients with severe COPD can exhibit compromised "inflammatory status", characterized by higher IL6, IL-6/IL-10 ratio and lower IL-10 concentration. Furthermore, IL-10 seems to be an interesting cytokine to be investigated in this kind of patients.

The value of blood cytokines and chemokines in assessing COPD

BACKGROUND

Blood biomarkers are increasingly used to stratify high risk chronic obstructive pulmonary disease (COPD) patients; however, there are fewer studies that have investigated multiple biomarkers and replicated in multiple large well-characterized cohorts of susceptible current and former smokers.

METHODS

We used two MSD multiplex panels to measure 9 cytokines and chemokines in 2123 subjects from COPDGene and 1117 subjects from SPIROMICS. These biomarkers included: interleukin (IL)-2, IL-6, IL-8, IL-10, tumor necrosis factor (TNF)-α, interferon (IFN)-γ, eotaxin/CCL-11, eotaxin-3/CCL-26, and thymus and activation-regulated chemokine (TARC)/CCL-17. Regression models adjusted for clinical covariates were used to determine which biomarkers were associated with the following COPD phenotypes: airflow obstruction (forced expiratory flow at 1 s (FEV1%) and FEV1/forced vital capacity (FEV1/FVC), chronic bronchitis, COPD exacerbations, and emphysema. Biomarker-genotype associations were assessed by genome-wide association of single nucleotide polymorphisms (SNPs).

RESULTS

Eotaxin and IL-6 were strongly associated with airflow obstruction and accounted for 3-5% of the measurement variance on top of clinical variables. IL-6 was associated with progressive airflow obstruction over 5 years and both IL-6 and IL-8 were associated with progressive emphysema over 5 years. None of the biomarkers were consistently associated with chronic bronchitis or COPD exacerbations. We identified one novel SNP (rs9302690 SNP) that was associated with CCL17 plasma measurements.

CONCLUSION

When assessing smoking related pulmonary disease, biomarkers of inflammation such as IL-2, IL-6, IL-8, and eotaxin may add additional modest predictive value on top of clinical variables alone.

TRIAL REGISTRATION

COPDGene (ClinicalTrials.gov Identifier: NCT02445183 ). Subpopulations and Intermediate Outcomes Measures in COPD Study (SPIROMICS) ( ClinicalTrials.gov Identifier: NCT 01969344 ).

Concomitant elevations of MMP-9, NGAL, proMMP-9/NGAL and neutrophil elastase in serum of smokers with chronic obstructive pulmonary disease

A growing body of evidence points towards smoking‐related phenotypic differences in chronic obstructive pulmonary disease (COPD). As COPD is associated with systemic inflammation, we determined whether smoking status is related to serum levels of matrix metalloproteinase‐9 (pro‐ and active MMP‐9), neutrophil gelatinase‐associated lipocalin (NGAL) and the proMMP‐9/NGAL complex in patients with COPD. Serum samples were collected in 100 stable‐phase COPD patients (82 smokers, 18 never‐smokers) and 28 healthy adults (21 smokers, 7 never‐smokers). Serum levels of studied factors were measured in ELISA. Our data provide the first evidence of simultaneously elevated serum levels of MMP‐9, NGAL and proMMP‐9/NGAL in COPD smokers. While the triad discriminated between smokers and non‐smokers in the COPD group, MMP‐9 and proMMP‐9/NGAL (but not NGAL) discriminated between smokers with and without COPD. Adjustment for age and smoking pack‐years did not alter the findings. Serum MMP‐9, NGAL and proMMP‐9/NGAL levels were not correlated with the GOLD stage or FEV1 decline. Furthermore, serum levels of neutrophil elastase (NE) and MMP‐3 (but not of IL‐6 and MMP‐12) were also higher in COPD smokers than in healthy smokers before and after adjustment for age and pack‐years. Among COPD smokers, levels of MMP‐9, NGAL and proMMP‐9/NGAL were positively correlated with NE (P < 0.0001) but not with the remaining factors. Gelatin zymography detected proMMP‐9 in serum samples of healthy and COPD smoking groups. Our results suggest that associated serum levels of proMMP‐9, NGAL, proMMP‐9/NGAL and NE may reflect the state of systemic inflammation in COPD related to cigarette smoking.

The Ser82 RAGE Variant Affects Lung Function and Serum RAGE in Smokers and sRAGE Production In Vitro

INTRODUCTION

Genome-Wide Association Studies have identified associations between lung function measures and Chronic Obstructive Pulmonary Disease (COPD) and chromosome region 6p21 containing the gene for the Advanced Glycation End Product Receptor (AGER, encoding RAGE). We aimed to (i) characterise RAGE expression in the lung, (ii) identify AGER transcripts, (iii) ascertain if SNP rs2070600 (Gly82Ser C/T) is associated with lung function and serum sRAGE levels and (iv) identify whether the Gly82Ser variant is functionally important in altering sRAGE levels in an airway epithelial cell model.

METHODS

Immunohistochemistry was used to identify RAGE protein expression in 26 human tissues and qPCR was used to quantify AGER mRNA in lung cells. Gene expression array data was used to identify AGER expression during lung development in 38 fetal lung samples. RNA-Seq was used to identify AGER transcripts in lung cells. sRAGE levels were assessed in cells and patient serum by ELISA. BEAS2B-R1 cells were transfected to overexpress RAGE protein with either the Gly82 or Ser82 variant and sRAGE levels identified.

RESULTS

Immunohistochemical assessment of 6 adult lung samples identified high RAGE expression in the alveoli of healthy adults and individuals with COPD. AGER/RAGE expression increased across developmental stages in human fetal lung at both the mRNA (38 samples) and protein levels (20 samples). Extensive AGER splicing was identified. The rs2070600T (Ser82) allele is associated with higher FEV1, FEV1/FVC and lower serum sRAGE levels in UK smokers. Using an airway epithelium model overexpressing the Gly82 or Ser82 variants we found that HMGB1 activation of the RAGE-Ser82 receptor results in lower sRAGE production.

CONCLUSIONS

This study provides new information regarding the expression profile and potential role of RAGE in the human lung and shows a functional role of the Gly82Ser variant. These findings advance our understanding of the potential mechanisms underlying COPD particularly for carriers of this AGER polymorphism.

Expression of RANKL by peripheral neutrophils and its association with bone mineral density in COPD

BACKGROUND AND OBJECTIVE

Osteoporosis is a major co-morbidity of COPD, but the mechanistic links between diseases of the lung and the bone remain elusive. Human neutrophils express the osteoclast activation factor RANKL (receptor activator of NF-kB ligand) and act directly on osteoclasts to promote bone loss. Given that neutrophils are key effector cells in the pathogenesis of COPD, these same cells, by expressing RANKL, may be involved in osteoporosis of COPD.

METHODS

We enrolled 59 male patients with COPD, 32 smokers with normal lung function and 25 healthy non-smokers of the same gender as controls. The expression of RANKL on peripheral neutrophils was detected by flow cytometry. The plasma concentrations of pro-inflammatory cytokines were measured by ELISA. We analysed the association of RANKL ⁺ neutrophils with bone mineral density (BMD), lung function and the levels of cytokines.

RESULTS

RANKL ⁺ neutrophils in the blood of COPD patients were increased as compared to smokers and healthy controls, and the percentage of RANKL ⁺ neutrophils was higher in patients with low BMD as compared to those with normal BMD. The percentage of RANKL ⁺ neutrophils showed negative correlations with BMD and forced expiratory volume in 1 s (FEV1) % predicted. Further analysis showed that activated neutrophils were increased and expressed a higher level of RANKL in COPD patients. Plasma levels of IL-1β, IL-6 and IL-8 were increased in COPD patients and correlated with RANKL expression by neutrophils.

CONCLUSION

Our results show that RANKL-expressing neutrophils are increased in male patients with COPD and associated with BMD and lung function, suggesting that these cells may play a role in osteoclastogenesis in COPD.

S100A12 is up-regulated in pulmonary tuberculosis and predicts the extent of alveolar infiltration on chest radiography: an observational study

Pulmonary tuberculosis (PTB) results in lung functional impairment and there are no surrogate markers to monitor the extent of lung involvement. We investigated the clinical significance of S100A12 and soluble receptor for advanced glycation end-products (sRAGE) for predicting the extent of lung involvement. We performed an observational study in India with 119 newly diagnosed, treatment naïve, sputum smear positive, HIV-negative PTB patients and 163 healthy controls. All patients were followed-up for six months. Sociodemographic variables and the serum levels of S100A12, sRAGE, esRAGE, HMGB-1, TNF-α, IFN-γ and CRP were measured. Lung involvement in PTB patients was assessed by chest radiography. Compared with healthy controls, PTB patients had increased serum concentrations of S100A12 while sRAGE was decreased. S100A12 was an independent predictor of disease occurrence (OR 1.873, 95%CI 1.212-2.891, p = 0.004). Under DOTS therapy, S100A12 decreased significantly after 4 months whereas CRP significantly decreased after 2 months (p < 0.0001). Importantly, although CRP was also an independent predictor of disease occurrence, only S100A12 was a significant predictor of lung alveolar infiltration (OR 2.60, 95%CI 1.35-5.00, p = 0.004). These results suggest that S100A12 has the potential to assess the extent of alveolar infiltration in PTB.

Chronic cerebral hypoperfusion-induced impairment of Aβ clearance requires HB-EGF-dependent sequential activation of HIF1α and MMP9

Chronic cerebral hypoperfusion (CCH) manifests Alzheimer's Disease (AD) neuropathology, marked by increased amyloid beta (Aβ). Besides, hypoxia stimulates Heparin-binding EGF-like growth factor (HB-EGF) mRNA expression in the hippocampus. However, involvement of HB-EGF in CCH-induced Aβ pathology remains unidentified. Here, using Bilateral Common Carotid Artery Occlusion mouse model, we explored the mechanism of HB-EGF regulated Aβ induction in CCH. We found that HB-EGF inhibition suppressed, while exogenous-HB-EGF triggered hippocampal Aβ, proving HB-EGF-dependent Aβ increase. We also detected that HB-EGF affected the expression of primary Aβ transporters, receptor for advanced glycation end-products (RAGE) and lipoprotein receptor-related protein-1 (LRP-1), indicating impaired Aβ clearance across the blood-brain barrier (BBB). An HB-EGF-dependent loss in BBB integrity supported impaired Aβ clearance. The effect of HB-EGF on Amyloid Precursor Protein pathway was relatively insignificant, suggesting a lesser effect on Aβ generation. Delving into BBB disruption mechanism demonstrated HB-EGF-mediated stimulation of Matrix metalloprotease-9 (MMP9), which affected BBB via HB-EGF-ectodomain shedding and epidermal growth factor receptor activation. Examining the intersection of HB-EGF-regulated pathway and hypoxia revealed HB-EGF-dependent increase in transcription factor, Hypoxia-inducible factor-1alpha (HIF1α). Further, via binding to hypoxia-responsive elements in MMP9 gene, HIF1α stimulated MMP9 expression, and therefore appeared as a prominent intermediary in HB-EGF-induced BBB damage. Overall, our study reveals the essential role of HB-EGF in triggering CCH-mediated Aβ accumulation. The proposed mechanism involves an HB-EGF-dependent HIF1α increase, generating MMP9 that stimulates soluble-HB-EGF/EGFR-induced BBB disintegration. Consequently, CCH-mediated hippocampal RAGE and LRP-1 deregulation together with BBB damage impair Aβ transport and clearance where HB-EGF plays a pivotal role.

The Neutrophil to Lymphocyte Ratio Is Related to Disease Severity and Exacerbation in Patients with Chronic Obstructive Pulmonary Disease

Objective Although chronic obstructive pulmonary disease (COPD) is characterized by systemic inflammation, the association between the neutrophil to lymphocyte ratio (NLR; an indicator of inflammation) and the clinical status of COPD has not been well studied. We hypothesized that the NLR is associated with disease severity and exacerbation in COPD patients. Methods We performed blood testing, pulmonary function testing, chest computed tomography, a body composition analysis, and a 6-minute walk test and applied the modified Medical Research Council (MMRC) dyspnea scale for 141 stable COPD patients. In addition, we calculated the body mass index, airflow obstruction, dyspnea, and exercise capacity (BODE) index to evaluate the disease severity. Finally, we examined the association between the NLR and clinical parameters in stable COPD patients, and we further investigated changes in the NLR between exacerbation and the stable state. Results The NLR was positively correlated with the BODE index, extent of emphysema, and MMRC score (p<0.001 for all), while inversely correlated with airflow obstruction (p<0.001), body mass index (p<0.001), fat-free mass index (p=0.001), and the 6-minute walk distance (p<0.001). We obtained the NLR during exacerbation from 49 patients. The NLR was significantly higher at exacerbation compared to the stable state (p<0.001). Conclusion The NLR was associated with disease severity and exacerbation in COPD patients. Therefore, the usefulness of the NLR in COPD patients should be elucidated in clinical settings in future investigations.

Circulating soluble receptor for advanced glycation end products (sRAGE) as a biomarker of emphysema and the RAGE axis in the lung

Chronic obstructive pulmonary disease (COPD) is a complex and heterogeneous disease that has been traditionally characterized by incompletely reversible airflow limitation. Yet, the latter is poorly correlated with many other clinically relevant characteristics of the disease. Thus, the identification of biomarkers to more accurately assess this heterogeneity and disease severity may facilitate the discovery and development of new treatments and better management of patients with COPD. One molecule that has attracted attention as a potentially useful biomarker specifically for the emphysema subpopulation is the soluble receptor for advanced glycation end products (sRAGE). As the soluble isoform of a key proinflammatory signaling receptor, sRAGE acts as a "decoy" for RAGE ligands and prevents their interaction with the receptor. Multiple reports have now linked sRAGE to COPD, and more specifically to emphysema, and evidence is accumulating that this link is likely mechanistic in nature. Here we review the current state of knowledge about sRAGE biology, the mechanistic links to COPD, and the evidence for using it as a biomarker for emphysema. We also discuss sRAGE as a potential target for therapeutic intervention in COPD.

CD4+ T-Cell Profiles and Peripheral Blood Ex-Vivo Responses to T-Cell Directed Stimulation Delineate COPD Phenotypes

The heterogeneous clinical phenotypes of chronic obstructive pulmonary disease (COPD) challenge successful drug development. To identify COPD subgroups beyond clinical phenotypes, we interrogated blood immune cell profiles and ex-vivo responses of current and former smokers, with or without COPD, in the longitudinal COPD Genetic Epidemiology study (COPDGene) cohort. CD4+ and CD8+ T cells and monocytes were profiled by flow cytometry. Microarray analysis was performed on the RNA from the aforementioned isolated cells. T-cell directed whole blood ex-vivo stimulation was used to assess functional responses. Blood CD4+ T-cell transcript analysis distinguished patients with COPD from control smokers and also enriched for a subset of patients with COPD that had a history of exacerbations of the disease. Analogous analyses of CD8+ T cells and monocytes failed to discriminate patients with COPD from the control population. Patients with COPD had a diminished cytokine response, compared to control smokers, characterized by low levels of granulocyte-monocyte colony stimulation factor (GM-CSF), interferon gamma (IFN-ɣ), interleukin one-alpha (IL-1α), tumor necrosis factor-alpha (TNF-α) and tumor necrosis factor-beta (TNF-β) secreted in response to T-cell directed ex-vivo stimulation. This cytokine response associated with baseline disease severity (forced expiratory volume in 1 second [FEV₁]% predicted), rapidly declining lung function, and emphysema. Our observations indicate that COPD phenotypes can be further differentiated based on blood CD4+ T-cell profiles and resultant immune responses, suggesting a role for these cells in COPD pathophysiology.

Constant-load exercise decreases the serum concentration of myeloperoxidase in healthy smokers and smokers with COPD

There is an ongoing demand for easily accessible biomarkers related to pathophysiological processes in chronic obstructive pulmonary disease (COPD). Short-term intense exercise is known to increase the peripheral blood levels of cytokines. Therefore, we tested the potential and the repeatability of an exercise challenge to amplify seven serum biomarkers (interleukin 6 [IL6], C-reactive protein [CRP], myeloperoxidase [MPO], leukotriene B4, soluble intercellular adhesion molecule 1, soluble vascular cell adhesion molecule 1, and von Willebrand factor [VWF]) in smokers with and without COPD. Twenty-three smokers with moderate COPD (GOLD 2) and 23 sex- and age-matched healthy smokers underwent up to 30-minute submaximal, constant-load exercise (75% of maximum work load) on two occasions separated by 4 weeks (second challenge n=19/20). Serum samples were obtained before, 5 minutes after the start, at the end of exercise (maximum 30 minutes or until exhaustion), and after additional 20 minutes of rest. The median (interquartile range) exercise time until exhaustion in the two challenges was 10.0 (4.0) minutes and 10.0 (8.0) minutes in smokers with COPD and 22.0 (16.0) minutes and 26.5 (14.5) minutes in healthy smokers. The exercise challenge significantly increased the serum concentrations of IL6 and VWF, but decreased the concentrations of MPO. Healthy smokers showed a significantly greater increase (at the end of exercise compared to before exercise) in IL6 (P=0.01) and a larger decline (P=0.03) in MPO. The overall profile of the serum markers during the exercise challenge was shown to be repeatable in the second challenge. In summary, intense load exercise is capable of changing the concentration of inflammatory and endothelial function markers. Especially, the decline in the level of MPO, a marker closely related to cardiovascular risk, appears to be of clinical interest, as the exercise-induced decline might be related to the beneficial effects of physical activity in general.

S100A8, S100A9 and S100A12 activate airway epithelial cells to produce MUC5AC via extracellular signal-regulated kinase and nuclear factor-κB pathways

Airway mucus hyperproduction is a common feature of chronic airway diseases such as severe asthma, chronic obstructive pulmonary disease and cystic fibrosis, which are closely associated with neutrophilic airway inflammation. S100A8, S100A9 and S100A12 are highly abundant proteins released by neutrophils and have been identified as important biomarkers in many inflammatory diseases. Herein, we report a new role for S100A8, S100A9 and S100A12 for producing MUC5AC, a major mucin protein in the respiratory tract. All three S100 proteins induced MUC5AC mRNA and the protein in normal human bronchial epithelial cells as well as NCI-H292 lung carcinoma cells in a dose-dependent manner. A Toll-like receptor 4 (TLR4) inhibitor almost completely abolished MUC5AC expression by all three S100 proteins, while neutralization of the receptor for advanced glycation end-products (RAGE) inhibited only S100A12-mediated production of MUC5AC. The S100 protein-mediated production of MUC5AC was inhibited by the pharmacological agents that block prominent signalling molecules for MUC5AC expression, such as mitogen-activated protein kinases, nuclear factor-κB (NF-κB) and epidermal growth factor receptor. S100A8, S100A9 and S100A12 equally elicited both phosphorylation of extracellular signal-regulated kinase (ERK) and nuclear translocation of NF-κB/degradation of cytosolic IκB with similar kinetics through TLR4. In contrast, S100A12 preferentially activated the ERK pathway rather than the NF-κB pathway through RAGE. Collectively, these data reveal the capacity of these three S100 proteins to induce MUC5AC production in airway epithelial cells, suggesting that they all serve as key mediators linking neutrophil-dominant airway inflammation to mucin hyperproduction.