Novel Applications of Biomarkers in Chronic Obstructive Pulmonary Disease

Chronic obstructive pulmonary disease (COPD) is an important health problem and an increasing cause of morbidity and mortality worldwide. Currently, COPD is considered a multisystem disease. Although it primarily affects the lungs, structural and functional changes occur in other organs due to systemic inflammation. It is stated that in patients with COPD, airway and systemic inflammatory markers are increased and that these markers are high are associated with a faster decline in lung functions. In recent years, numerous articles have been published on the discovery and evaluation of biomarkers in COPD. Many markers have also been studied to accurately assess COPD exacerbations and provide effective treatment. However, based on the evidence from published studies, a single molecule has not been adequately validated for broad clinical use.

Association of serum surfactant protein D and SFTPD gene variants with asthma in Danish children, adolescents, and young adults

BACKGROUND

Surfactant Protein D (SP-D) is a pattern recognition molecule belonging to the family of collectins expressed in multiple human organ systems, including the lungs. Previous studies have shown that SP-D levels in bronchoalveolar lavage samples decrease and serum levels increase in patients suffering from asthma, possibly due to a combination of induced SP-D synthesis and decreased air-blood barrier integrity. The aims of this study were to investigate whether serum levels of SP-D and common variants in the SP-D gene were associated with asthma in adolescents and young adults.

METHODS

Prospective observational study including 449 adolescents and young adults (age 11-27 years) previously diagnosed with asthma during a 2-year period from 2003 to 2005 (0-16 years). At follow-up from 2016 to 2017, 314 healthy controls with no history of asthma were recruited. Serum SP-D was analyzed on samples obtained at baseline as well as samples obtained at follow-up. SP-D genotyping was performed for rs721917, rs2243639, and rs3088308.

RESULTS

No differences were found in mean levels of sSP-D and SFTPD genotype among subjects with current asthma, no current asthma, and controls. Serum SP-D and SFTPD genotype were not associated with any clinical parameters of asthma. Furthermore, baseline sSP-D was not associated with asthma at follow-up.

CONCLUSION

Serum surfactant protein D and common SP-D gene variants were not associated with asthma in Danish adolescents and young adults with mild to moderate asthma. Serum surfactant protein D did not demonstrate any value as a clinical biomarker of asthma.

Association of surfactant protein D with pulmonary metastases from colon cancer

Surfactant protein D (SP-D) is a member of the collectin family of proteins, which is secreted by airway epithelial cells. SP-D serves an important role in the immune system and in the inflammatory regulation of the lung. SP-D was recently found to suppress lung cancer progression by downregulating epidermal growth factor signaling. However, the relationship between SP-D and pulmonary metastases from colon cancer remains unknown. The present study aimed to determine whether SP-D may suppress the development of the mouse rectal carcinoma cell line, CMT93, in vitro. The present study investigated the effect of SP-D on pulmonary metastases from colon cancer in vivo using SP-D knockout mice. A wound healing assay and cell invasion assay revealed that SP-D suppressed the proliferation, migration and invasion of CMT-93 cells. After injection of CMT-93 cells into the tail vein, SP-D knockout mice were significantly more susceptible to developing pulmonary metastases than C57/BL6 mice (control). Moreover, a novel cell line (CMT-93 pulmonary metastasis; CMT-93 PM) was established from the lesions of pulmonary metastases in C57/BL6 mice following injection of CMT93 into the tail vein. CMT-93 PM exhibited more robust invasion and proliferation compared to CMT93, which was unaffected by exposure to SP-D. A higher incidence of pulmonary metastases was detected following injection of CMT93 PM into the tail vein of C57/BL6 mice compared with CMT-93. Consequently, SP-D may be involved in the pathogenesis of pulmonary metastases from colon cancer.

Serum Amyloid A in Stable COPD Patients is Associated with the Frequent Exacerbator Phenotype

Background

We sought to determine whether circulating inflammatory biomarkers were associated with the frequent exacerbator phenotype in stable COPD patients ie, those with two or more exacerbations in the previous year.

Methods

Eighty-eight stable, severe, COPD patients (4 females) were assessed for exacerbation frequency, pulmonary function, fraction of expired nitric oxide (F_ENO); inflammatory variables were measured in venous blood. Logistic regression assessed associations between the frequent exacerbator phenotype and systemic inflammation.

Results

Compared with infrequent exacerbators, frequent exacerbators (n=10; 11.4%) had greater serum concentration (median (25th-75th quartile)) of serum amyloid A (SAA; 134 (84–178) vs 71 (38–116) ng/mL; P=0.024), surfactant protein D (SP-D; 15.6 (9.0–19.3) vs 8.5 (3.6–14.9) ng/mL; P=0.049) and interleukin-4 (IL-4; 0.12 (0.08–1.44) vs 0.03 (0.01–0.10) pg/mL; P=0.001). SAA, SP-D and IL-4 were not significantly correlated with FEV₁%predicted or FVC %predicted. After adjusting for sex, age, BMI, FEV₁/FVC and smoking pack-years, only SAA remained independently associated with the frequent exacerbator phenotype (OR 1.49[1.09–2.04]; P=0.012). The odds of being a frequent exacerbator was 18-times greater in the highest SAA quartile (≥124.1 ng/mL) than the lowest SAA quartile (≤44.1 ng/mL) (OR 18.34[1.30–258.81]; P=0.031), and there was a significant positive trend of increasing OR with increasing SAA quartile (P=0.008). For SAA, the area under the receiver operating characteristic curve was 0.721 for identification of frequent exacerbators; an SAA cut-off of 87.0 ng/mL yielded an 80% sensitivity and 61.5% specificity.

Conclusion

In stable COPD patients, SAA was independently associated with the frequent exacerbator phenotype, suggesting that SAA may be a useful serum biomarker to inform progression or management in COPD.

A perspective for chronic obstructive pulmonary disease (COPD) management: six key clinical questions to improve disease treatment

INTRODUCTION

In 2011, the GOLD recommendations for the treatment of Chronic Obstructive Pulmonary Disease (COPD) introduced new clinical elements to classify the severity of the disease and to guide pharmacological choice. For the first time in the GOLD documents, treatment decision was no longer guided only by pulmonary function, but by a more complex combination of pulmonary function and clinical aspects. The recent versions of the GOLD recommendations introduce new aspects for the clinicians and pose new question for the management of the disease. In addition, inflammatory biomarkers and blood eosinophil levels, have been considered to guide treatment selection.

AREA COVERED

The evolution of disease management proposed by the GOLD document opens several areas of debate. A series of roundtable discussions among respiratory physicians took place in Italy to address key clinical questions. Particularly, the role of lung function and the use of biomarkers, the adherence to international guidelines and the possibility to personalize the pharmacological approach in COPD patients have been discussed, summarized and analyzed.

EXPERT OPINION

The authors believe that the development of a precision medicine approach tailoring the specific treatment for each patient is the goal of COPD management and may be achieved by considering the phenotypic classification of COPD patients.

Simvastatin Therapy and Bronchoalveolar Lavage Fluid Biomarkers in Chronic Obstructive Pulmonary Disease

Chronic obstructive pulmonary disease (COPD) is a progressive disease underlain by airway inflammation. Despite trials with new generations of anti-inflammatory drugs to alleviate the disease burden, the effective curative treatment remains elusive. In this context, the aim of this study was to assess the influence of simvastatin, a leading member of the family of 3-hydroxy-3-methylglutaryl coenzyme A (HMG-CoA) reductase inhibitors, known to display anti-inflammatory and immunomodulatory activity, on symptoms and lung function, as well as the proportion of inflammatory cells, cytokines, proteolytic enzymes, and surfactant protein D (SP-D) content in bronchoalveolar lavage fluid (BALF) in COPD patients. There were 50 patients with moderate-to-severe airway obstructions included into the study, subdivided into simvastatin-treated (Zocor - MSD; 40 mg daily) and control simvastatin-untreated groups, other treatment being equal. Pulmonary functions tests and bronchofiberoscopy with BALF procedure were performed before and after 3-month-long treatment in both groups. The major finding was that simvastatin treatment caused a distinct increase in the airway content of SP-D. Further effects, albeit smaller in magnitude, consisted of reductions in the proportion of airway neutrophils and in MMP-9 content, all with a benefit of improved score in the disease activity assessment test. There were no appreciable changes noted in lung function or dyspnea perception, which could be ascribed to simvastatin treatment. We conclude that statin's anti-inflammatory and surfactant homeostasis preserving properties may offer promise as an adjunctive treatment in COPD patients. The SP-D content in BALF has a potential to become a marker of COPD inflammatory activity and treatment monitoring.

Pulmonary Function and Sleep Breathing: Two New Targets for Type 2 Diabetes Care

Population-based studies showing the negative impact of type 2 diabetes (T2D) on lung function are overviewed. Among the well-recognized pathophysiological mechanisms, the metabolic pathways related to insulin resistance (IR), low-grade chronic inflammation, leptin resistance, microvascular damage, and autonomic neuropathy are emphasized. Histopathological changes are exposed, and findings reported from experimental models are clearly differentiated from those described in humans. The accelerated decline in pulmonary function that appears in patients with cystic fibrosis (CF) with related abnormalities of glucose tolerance and diabetes is considered as an example to further investigate the relationship between T2D and the lung. Furthermore, a possible causal link between antihyperglycemic therapies and pulmonary function is examined. T2D similarly affects breathing during sleep, becoming an independent risk factor for higher rates of sleep apnea, leading to nocturnal hypoxemia and daytime sleepiness. Therefore, the impact of T2D on sleep breathing and its influence on sleep architecture is analyzed. Finally, the effect of improving some pathophysiological mechanisms, primarily IR and inflammation, as well as the optimization of blood glucose control on sleep breathing is evaluated. In summary, the lung should be considered by those providing care for people with diabetes and raise the central issue of whether the normalization of glucose levels can improve pulmonary function and ameliorate sleep-disordered breathing. Therefore, patients with T2D should be considered a vulnerable group for pulmonary dysfunction. However, further research aimed at elucidating how to screen for the lung impairment in the population with diabetes in a cost-effective manner is needed.

Surfactant protein D is a causal risk factor for COPD: results of Mendelian randomisation

Surfactant protein D (SP-D) is produced primarily in the lung and is involved in regulating pulmonary surfactants, lipid homeostasis and innate immunity. Circulating SP-D levels in blood are associated with chronic obstructive pulmonary disease (COPD), although causality remains elusive.In 4061 subjects with COPD, we identified genetic variants associated with serum SP-D levels. We then determined whether these variants affected lung tissue gene expression in 1037 individuals. A Mendelian randomisation framework was then applied, whereby serum SP-D-associated variants were tested for association with COPD risk in 11 157 cases and 36 699 controls and with 11 years decline of lung function in the 4061 individuals.Three regions on chromosomes 6 (human leukocyte antigen region), 10 (SFTPD gene) and 16 (ATP2C2 gene) were associated with serum SP-D levels at genome-wide significance. In Mendelian randomisation analyses, variants associated with increased serum SP-D levels decreased the risk of COPD (estimate -0.19, p=6.46×10^-03) and slowed the lung function decline (estimate=0.0038, p=7.68×10^-3).Leveraging genetic variation effect on protein, lung gene expression and disease phenotypes provided novel insights into SP-D biology and established a causal link between increased SP-D levels and protection against COPD risk and progression. SP-D represents a very promising biomarker and therapeutic target for COPD.

Serum Surfactant Protein D as a Biomarker for Measuring Lung Involvement in Obese Patients With Type 2 Diabetes

CONTEXT

Lung impairment is a new target for late diabetic complications. Biomarkers that could help identify patients requiring functional respiratory tests have not been reported.

OBJECTIVE

Our aim was to examine whether serum surfactant protein D (SP-D) and A (SP-A) could be useful biomarkers of lung damage in obese patients with type 2 diabetes (T2D) without known lung disease.

DESIGN AND SETTING

A case-control study conducted in an ambulatory obesity unit.

PATIENTS

Forty-nine obese patients with T2D and 98 subjects without diabetes matched by age, sex, body mass index, and waist circumference were included.

INTERVENTIONS

Serum SP-D and SP-A levels were measured using enzyme-linked immunosorbent assay. Forced spirometry and static pulmonary volume were assessed.

RESULTS

Patients with T2D exhibited higher serum SP-D concentrations than control subjects (P = 0.006). No differences in serum SP-A concentrations were observed. There was an inverse association between forced expiratory volume in 1 second (FEV1) and serum SP-D (r = -0.265; P = 0.029), as well as a significant positive relationship between SP-D concentration and residual volume (r = 0.293; P = 0.043). From receiver operating characteristic analysis, the best SP-D cutoff to identify a FEV1 <80% of predicted was 132.3 ng/mL (area under the curve, 0.725; sensitivity, 77.7%; specificity, 69.4%). Stepwise multivariate regression analysis showed that serum SP-D concentration ≥132.3 ng/mL was independently associated with a FEV1 <80% of predicted (R2 = 0.406). Only the existence of T2D contributed independently to serum SD-P variance among all subjects (R2 = 0.138).

CONCLUSIONS

Serum SP-D concentration can be a useful biomarker for detecting lung impairment in obese patients with T2D.

Impact of anti-tumor necrosis factor-α agents on serum levels of KL-6 and surfactant protein-D in patients with psoriasis

We longitudinally examined the influence of anti-tumor necrosis factor (TNF)-α treatment on serum levels of KL-6 and surfactant protein-D (SP-D). The study group comprised 22 patients with psoriasis treated with infliximab or adalimumab and with no history of interstitial lung disease (ILD). KL-6 and SP-D levels were measured in serum samples. Twelve of the 22 patients (55%) showed at least a 20% increase in KL-6 levels compared with baseline. Of these 12 patients, none exhibited any signs of ILD on chest computed tomography and nine who showed an increase in KL-6 levels (75%) showed at least a 20% increase in SP-D levels. Some patients showed simultaneous increases in KL-6 and SP-D levels after treatment with anti-TNF-α agents. Although these patients may have undetectable or subtle alveolar damage, careful observation is needed.

Potential inflammatory markers in obstructive sleep apnea-hypopnea syndrome

Obstructive sleep apnea-hypopnea syndrome (OSAHS) is a complex chronic inflammatory respiratory disease with multiple pathogenic factors and high morbidity and mortality. Serum levels of nuclear factor-κB (NF-κB), hypoxia-inducible factor-1 alpha (HIF-1α), and surfactant protein D (SPD) were investigated in OSAHS patients, to determine their clinical significance and correlation with the pathogenesis. Patients were classified into a mild and moderate OSAHS group (n = 25) and severe OSAHS group (n = 33). Twenty healthy patients served as a control group. Peripheral blood levels of NF-κB, HIF-1α, and SPD were determined by Western blot, and a correlation analysis was performed. Severe OSAHS patients received nasal continuous positive airway pressure (nCPAP) therapy and were followed up after 2 months. NF-κB p65, HIF-1α, and SPD expression levels were determined after valid nCPAP therapy. NF-κB p65 and HIF-1α expression was significantly higher in severe OSAHS group than in the other two groups (p < 0.01), and was positively correlated with the apnea-hypopnea index (AHI) (r = 0.696, p < 0.001; r = 0.634, p < 0.001). SPD expression was significantly lower in severe OSAHS group than in the control group (p < 0.01) and mild and moderate OSAHS group (p < 0.01), and was negatively correlated with AHI (r = -0.569, p < 0.001). OSAHS pathogenesis was associated with changes in NF-κB, HIF-1α, and SPD protein expression levels. nCPAP therapy could improve the clinical characteristics of the patients, lower serum NF-κB and HIF-1α levels, and increase serum SPD levels. We conclude that OSAHS is related to the expression of NF-κB, HIF-1, and SPD.

Factors associated with experience of fatigue, and functional limitations due to fatigue in patients with stable COPD

BACKGROUND

The aim of this study was to determine the influence of selected physiological, psychological and situational factors on experience of fatigue, and functional limitations due to fatigue in patients with stable chronic obstructive pulmonary disease (COPD).

METHODS

In total 101 patients with COPD and 34 control patients were assessed for experience of fatigue, functional limitation due to fatigue (Fatigue Impact Scale), physiological [lung function, 6-minute walk distance (6MWD), body mass index (BMI), dyspnoea, interleukin (IL)-6, IL-8, high sensitivity C-reactive protein (hs-CRP), surfactant protein D], psychological (anxiety, depression, insomnia), situational variables (age, sex, smoking, living alone, education), and quality of life.

RESULTS

Fatigue was more common in patients with COPD than in control patients (72% versus 56%, p < 0.001). Patients with COPD and fatigue had lower lung function, shorter 6MWD, more dyspnoea, anxiety and depressive symptoms, and worse health status compared with patients without fatigue (all p < 0.01). No differences were found for markers of systemic inflammation. In logistic regression, experience of fatigue was associated with depression [odds ratio (OR) 1.69, 95% confidence interval (CI) 1.28-2.25) and insomnia (OR 1.75, 95% CI 1.19-2.54). In linear regression models, depression, surfactant protein D and dyspnoea explained 35% (R(2)) of the variation in physical impact of fatigue. Current smoking and depression explained 33% (R(2)) of the cognitive impact of fatigue. Depression and surfactant protein D explained 48% (R(2)) of the psychosocial impact of fatigue.

CONCLUSIONS

Experiences of fatigue and functional limitation due to fatigue seem to be related mainly to psychological but also to physiological influencing factors, with depressive symptoms, insomnia problems and dyspnoea as the most prominent factors. Systemic inflammation was not associated with perception of fatigue but surfactant protein D was connected to some dimensions of the impact of fatigue.

Club Cell-16 and RelB as Novel Determinants of Arterial Stiffness in Exacerbating COPD Patients

Background

Exacerbations of chronic obstructive pulmonary disease (COPD) are acute events of worsened respiratory symptoms that may increase the risk of cardiovascular disease (CVD), a leading cause of mortality amongst COPD patients. The utility of lung-specific inflammatory mediators such as club cell protein-16 (CC-16) and surfactant protein D (SPD) and that of a novel marker of CV outcomes in COPD- RelB- in predicting adverse cardiovascular events during exacerbation is not known.

Methods

Thirty-eight subjects with COPD admitted to the hospital for severe exacerbation were included in this analysis. Clinical, physiological and arterial stiffness measurements were performed within 72 hours of admission; this was followed by measurements taken every 3 days until hospital discharge, then once a week until 30 days after discharge, and then again at 90 and 180 days. Plasma concentrations of inflammatory mediators were measured from peripheral venous blood taken at admission, and at days 15, 30, 90 and 180.

Results

CC-16 and RelB concentrations were increased at day 15 of exacerbations whereas SPD concentrations were decreased. The course of change in CC-16 and RelB levels over time was inversely associated with that of carotid-femoral pulse wave velocity, the gold-standard measure of arterial stiffness. Increases in CC-16 could predict a decreased number of subsequent exacerbations during follow-up.

Conclusions

Lung-specific (CC-16) and novel (RelB) biomarkers are associated with systemic cardiovascular changes over time. CC-16 can predict subsequent exacerbations in subjects with severe COPD and may be an important biomarker of pulmonary and systemic stress in COPD.

The role of serum surfactant protein D as a biomarker of exacerbation of chronic obstructive pulmonary disease

BACKGROUND

The exacerbation of chronic obstructive pulmonary disease (COPD) is a major factor for the high mortality associated with the disease. There is a paucity in the lung-specific biomarkers which diagnose these exacerbations. Surfactant protein D (SP-D) is a promising biomarker in predicting clinical outcomes for patients with COPD, is lung-specific and can be detected in serum. However, the profile in which serum concentrations of SP-D change during acute exacerbation is still unclear. This study aims to estimate and compare the concentrations of serum SP-D in patients with stable disease and during the exacerbation.

METHODS

A cross-sectional study was conducted which composed of apparently healthy individuals (n = 28), which included 14 smokers and 14 nonsmokers, patients with stable COPD (n = 28), and patients experiencing acute exacerbations (n = 28). Pulmonary functions were performed for all groups. Serum SP-D concentrations were measured using enzyme-linked immunosorbent assay (ELISA). These concentrations were compared by analysis of variance.

RESULTS

Serum SP-D levels were significantly elevated in patients with acute exacerbations (508.733 ± 102.813 ng/ml) compared to patients with stable COPD (337.916 ± 86.265 ng/ml) and healthy subjects (177.313 ± 46.998 ng/ml; p <  0.001). Serum SP-D levels correlated inversely with lung function parameters including FEV1%pred, FVC%pred and FEV1/FVC.

CONCLUSION

Serum SP-D levels are raised early on during acute exacerbations of COPD, which could be a potential early diagnostic biomarker for COPD exacerbations.

Airway Surfactant Protein D Deficiency in Adults With Severe Asthma

BACKGROUND

Surfactant protein D (SP-D) is an essential component of the innate immune defense against pathogens within the airways. SP-D also regulates allergic inflammation and promotes the removal of apoptotic cells. SP-D dysregulation is evident in several pulmonary diseases. Our aim was to investigate whether airway and serum levels of SP-D are altered in treatment-resistant severe asthma.

METHODS

SP-D concentrations were measured in matched serum and BAL samples collected from 10 healthy control subjects (HC) and 50 patients with asthma (22 with mild asthma [MA] and 28 with severe asthma [SA]). These samples were also evaluated by using Western blot analysis to investigate variations in SP-D size.

RESULTS

SP-D levels in BAL samples were significantly lower in SA compared with HC and MA (P < .001) and inversely correlated with BAL eosinophil cationic protein concentrations in SA (P < .01). Serum SP-D was significantly increased in SA compared with HC and MA (P < .001), and BAL/serum ratios were significantly lower in SA compared with HC and MA (P < .001). Reduced SP-D levels in BAL samples, with concomitant increases in serum in SA, were associated with degraded fragments of SP-D in the serum and increased BAL neutrophil counts and lipopolysaccharide levels.

CONCLUSIONS

These findings suggest defective innate immunity within the airways in SA, as reflected by low BAL SP-D concentrations and altered bacterial presence with airway neutrophilia. Furthermore, BAL SP-D leakage into the serum in patients with SA may provide a peripheral blood biomarker, reflecting increased epithelial damage and/or epithelial permeability within the peripheral airways.

Increased expression of immune-related genes in leukocytes of patients with diagnosed gestational diabetes mellitus (GDM)

Compelling evidence indicates that the immune system is linked to metabolism in gestational diabetes mellitus (GDM), but factors participating in these processes still are awaiting identification. Inducible nitric oxide synthase, encoded by the NOS2 gene, and surfactant protein D, encoded by the SFTPD gene, have been implicated in diabetes. We investigated NOS2 and SFTPD mRNA levels in leukocytes obtained from 125 pregnant women with (n = 87) or without (control group; n = 38) GDM, and, in turn, correlated their expression with clinical parameters of subjects. Leukocytes were isolated from the blood of pregnant women and NOS2 and SFTPD expression in these cells was determined by quantitative real time PCR (qRT-PCR). Univariate correlation analyses were performed to assess an association between leukocyte NOS2 and SFTPD expression and clinical characteristics of patients. qRT-PCR experiments disclosed significantly increased leukocyte NOS2 and SFTPD mRNA levels in hyperglycemic GDM patients (P < 0.05). In the entire study group, there were significant positive associations of leukocyte NOS2 and SFTPD mRNAs with C-reactive protein. Additionally, transcript level of SFTPD also correlated positively with fasting glycemia and insulin resistance. This study demonstrates that an impaired glucose metabolism in GDM may be predominant predictor of leukocyte NOS2 and SFTPD overexpression in diabetic patients. Furthermore, alterations in the expression of these genes are associated with glucose metabolism dysfunction and/or inflammation during pregnancy. In addition, these findings support the utilization of leukocytes as good experimental model to study a relationship between immune-related genes and metabolic changes in women with GDM, as well as to assess the potential mechanisms underlying these alterations.

[Significance of surfactant proteins in the diagnosis of therapeutic diseases]

The lung provides not only respiration, but also the functioning of innate immunity mechanisms. The hydrophilic proteins SP-A and SP-D are responsible for the regulation of the latter. In the literature, there is evidence for elevated serum SP-A and SP-D levels in respiratory diseases accompanied by enhanced mucosal inflammation of the lung or its parenchymal injury and their association with age and cardiovascular diseases has been recently found. Studies of the efficiency of using SP-A and SP-D as specific markers for inflammatory lung diseases are presently worthwhile.

Integrative analysis of DNA methylation and gene expression data identifies EPAS1 as a key regulator of COPD

Chronic Obstructive Pulmonary Disease (COPD) is a complex disease. Genetic, epigenetic, and environmental factors are known to contribute to COPD risk and disease progression. Therefore we developed a systematic approach to identify key regulators of COPD that integrates genome-wide DNA methylation, gene expression, and phenotype data in lung tissue from COPD and control samples. Our integrative analysis identified 126 key regulators of COPD. We identified EPAS1 as the only key regulator whose downstream genes significantly overlapped with multiple genes sets associated with COPD disease severity. EPAS1 is distinct in comparison with other key regulators in terms of methylation profile and downstream target genes. Genes predicted to be regulated by EPAS1 were enriched for biological processes including signaling, cell communications, and system development. We confirmed that EPAS1 protein levels are lower in human COPD lung tissue compared to non-disease controls and that Epas1 gene expression is reduced in mice chronically exposed to cigarette smoke. As EPAS1 downstream genes were significantly enriched for hypoxia responsive genes in endothelial cells, we tested EPAS1 function in human endothelial cells. EPAS1 knockdown by siRNA in endothelial cells impacted genes that significantly overlapped with EPAS1 downstream genes in lung tissue including hypoxia responsive genes, and genes associated with emphysema severity. Our first integrative analysis of genome-wide DNA methylation and gene expression profiles illustrates that not only does DNA methylation play a ‘causal’ role in the molecular pathophysiology of COPD, but it can be leveraged to directly identify novel key mediators of this pathophysiology.

Chronic Obstructive Pulmonary Disease (COPD) is a common lung disease. It is the fourth leading cause of death in the world and is expected to be the third by 2020. COPD is a heterogeneous and complex disease consisting of obstruction in the small airways, emphysema, and chronic bronchitis. COPD is generally caused by exposure to noxious particles or gases, most commonly from cigarette smoking. However, only 20–25% of smokers develop clinically significant airflow obstruction. Smoking is known to cause epigenetic changes in lung tissues. Thus, genetics, epigenetic, and their interaction with environmental factors play an important role in COPD pathogenesis and progression. Currently, there are no therapeutics that can reverse COPD progression. In order to identify new targets that may lead to the development of therapeutics for curing COPD, we developed a systematic approach to identify key regulators of COPD that integrates genome-wide DNA methylation, gene expression, and phenotype data in lung tissue from COPD and control samples. Our integrative analysis identified 126 key regulators of COPD. We identified EPAS1 as the only key regulator whose downstream genes significantly overlapped with multiple genes sets associated with COPD disease severity.

Functional polymorphisms in surfactant protein genes and chronic obstructive pulmonary disease risk: a meta-analysis

AIMS

Increasing scientific evidence suggests that functional polymorphisms in surfactant protein (SP) genes may contribute to increasing susceptibility to chronic obstructive pulmonary disease (COPD), but many existing studies have yielded inconclusive results. This meta-analysis aims to assess the exact role of SP gene polymorphisms in the development of COPD.

METHODS

An extensive literature search for relevant studies was conducted on PubMed, Embase, Web of Science, Cochrane Library, and CBM databases from their inception through May 1st, 2013. This meta-analysis was performed using the STATA 12.0 software. The crude odds ratio (OR) with 95% confidence interval (CI) were calculated.

RESULTS

Seven case-control studies were included with a total of 2761 subjects, including 1274 COPD cases and 1482 healthy controls. Our meta-analysis revealed that common polymorphisms in the SP-A gene may be associated with an increased risk of COPD (allele model: OR=1.53, 95% CI: 1.14-2.05, p=0.005; dominant model: OR=1.65, 95% CI: 1.02-2.69, p=0.043; recessive model: OR=1.66, 95% CI: 1.17-2.35, p=0.005; homozygous model: OR=2.06, 95% CI: 1.24-3.41, p=0.005; heterozygous model: OR=1.59, 95% CI: 1.13-2.22, p=0.007), especially among Asian populations. However, there was no evidence for any association between common polymorphisms in the SP-B and SP-D genes and COPD risk (all p>0.05).

CONCLUSION

The current meta-analysis indicates that common polymorphisms in the SP-A gene may contribute to increasing susceptibility to COPD, especially among Asian populations.

Value of serum and induced sputum surfactant protein-D in chronic obstructive pulmonary disease

BACKGROUND

Surfactant Protein D (SP-D) is an important marker in chronic obstructive pulmonary disease (COPD). Serum SP-D levels increase while lung production of SP-D decreases in COPD. SP-D is a specific biomarker for monitoring COPD, assessment of exacerbation frequency and arrangement of treatment modalities. In the present study, we aimed to investigate the correlation between serum and induced sputum SP-D levels with severity and acute exacerbations of COPD.

METHOD

20 healthy subjects, older than 40 years, with at least 10 pack/years smoking history (group 1), 20 stage I-II COPD patients (group 2) , and 20 stage III-IV COPD patients (group 3) were enrolled in the study. All subjects performed pulmonary function tests. Venous blood samples were taken to determine complete blood count, C-reactive protein(CRP) and serum SP-D levels. Induced sputum samples were obtained to determine SP-D level. COPD patients were followed up for acute exacerbations for 6 months.

RESULTS

Serum SP-D levels of group 3 were the highest and induced sputum SP-D levels of group 2 were the lowest among the three groups. SP-D levels of induced sputum decreased in patients with increasing number of cigarette pack/years (p = 0.03, r = -0.115), whereas serum SP-D levels increased in these patients (p = 0.0001, r = 0.6 ). Induced sputum SP-D levels in COPD patients receiving inhaled corticosteroid treatment were significantly higher than in patients who were not receiving inhaler corticosteroid treatment (p = 0.005). An inverse correlation between serum SP-D levels and FEV1 (%) was found and there was a positive correlation between the serum SP-D levels and exacerbations frequency in 6-month follow up period (p = 0.049 ,r = -0.252; p = 0.0001, r = 0.598 respectively).

CONCLUSION

Our study demonstrates the adverse effects of smoking on local SP-D levels since low levels of induced sputum SP-D were found in the group of current smokers, who were not receiving inhaled corticosteroid treatment. Relationship between serum SP-D and COPD exacerbations frequency suggests that serum SP-D level may be used as a lung-specific biomarker during the follow up and progression of COPD.

Adiponectin: a novel link between adipocytes and COPD

Adiponectin (APN) is a unique adipokine with multiple salutary effects such as antiapoptotic, anti-inflammatory, and anti-oxidative activities in numerous organs and cells. Chronic obstructive pulmonary disease (COPD), a growing cause of mortality and morbidity worldwide, often results from the smoking habit and is considered a lifestyle-related disease. COPD is frequently complicated with comorbidities, such as cardiovascular disease, diabetes mellitus, and osteoporosis; however, the molecular mechanisms linking COPD and the associated comorbidities are poorly understood. Recent data have revealed a role for APN in the lung; mice lacking APN spontaneously develop a COPD-like phenotype with extrapulmonary effects, including systemic inflammation, body weight loss, and osteoporosis. This finding highlights the key role of APN in lung pathology and the novel cross talk between lung and adipose tissues. This review summarizes recent advances in understanding the physiological and pathological role of APN in the lung.

Biomarkers and bacterial pneumonia risk in patients with treated HIV infection: a case-control study

Background

Despite advances in HIV treatment, bacterial pneumonia continues to cause considerable morbidity and mortality in patients with HIV infection. Studies of biomarker associations with bacterial pneumonia risk in treated HIV-infected patients do not currently exist.

Methods

We performed a nested, matched, case-control study among participants randomized to continuous combination antiretroviral therapy (cART) in the Strategies for Management of Antiretroviral Therapy trial. Patients who developed bacterial pneumonia (cases) and patients without bacterial pneumonia (controls) were matched 1∶1 on clinical center, smoking status, age, and baseline cART use. Baseline levels of Club Cell Secretory Protein 16 (CC16), Surfactant Protein D (SP-D), C-reactive protein (hsCRP), interleukin-6 (IL-6), and d-dimer were compared between cases and controls.

Results

Cases (n = 72) and controls (n = 72) were 25.7% female, 51.4% black, 65.3% current smokers, 9.7% diabetic, 36.1% co-infected with Hepatitis B/C, and 75.0% were on cART at baseline. Median (IQR) age was 45 (41, 51) years with CD4+ count of 553 (436, 690) cells/mm³. Baseline CC16 and SP-D were similar between cases and controls, but hsCRP was significantly higher in cases than controls (2.94 µg/mL in cases vs. 1.93 µg/mL in controls; p = 0.02). IL-6 and d-dimer levels were also higher in cases compared to controls, though differences were not statistically significant (p-value 0.06 and 0.10, respectively).

Conclusions

In patients with cART-treated HIV infection, higher levels of systemic inflammatory markers were associated with increased bacterial pneumonia risk, while two pulmonary-specific inflammatory biomarkers, CC16 and SP-D, were not associated with bacterial pneumonia risk.

Surfactant protein D as a biomarker for chronic obstructive pulmonary disease

Clinical research in chronic obstructive pulmonary disease (COPD) has been hampered by the lack of validated blood biomarkers. The ideal COPD biomarker would have the following characteristics: (1) it would be a lung specific protein that could be assayed in blood; (2) it would change with disease severity or during exacerbations; (3) it would be specific for COPD; and would be responsive to change with effective treatments. One such candidate is the lung specific protein surfactant protein D (SP-D). In this review, we discuss the evidence supporting SP-D as a COPD biomarker.

Pulmonary Collectins in Diagnosis and Prevention of Lung Diseases

Pulmonary surfactant is a complex mixture of lipids and proteins, and is synthesized and secreted by alveolar type II epithelial cells and bronchiolar Clara cells. It acts to keep alveoli from collapsing during the expiratory phase of the respiratory cycle. After its secretion, lung surfactant forms a lattice structure on the alveolar surface, known as tubular myelin. Surfactant proteins (SP)-A, B, C and D make up to 10% of the total surfactant. SP-B and SPC are relatively small hydrophobic proteins, and are involved in the reduction of surface-tension at the air-liquid interface. SP-A and SP-D, on the other hand, are large oligomeric, hydrophilic proteins that belong to the collagenous Ca²⁺-dependent C-type lectin family (known as “Collectins”), and play an important role in host defense and in the recycling and transport of lung surfactant (Awasthi 2010) (Fig. 43.1). In particular, there is increasing evidence that surfactant-associated proteins A and -D (SP-A and SP-D, respectively) contribute to the host defense against inhaled microorganisms (see 10.1007/978-3-7091-1065_24 and 10.1007/978-3-7091-1065_25). Based on their ability to recognize pathogens and to regulate the host defense, SP-A and SP-D have been recently categorized as “Secretory Pathogen Recognition Receptors”. While SP-A and SP-D were first identified in the lung; the expression of these proteins has also been observed at other mucosal surfaces, such as lacrimal glands, gastrointestinal mucosa, genitourinary epithelium and periodontal surfaces. SP-A is the most prominent among four proteins in the pulmonary surfactant-system. The expression of SP-A is complexly regulated on the transcriptional and the chromosomal level. SP-A is a major player in the pulmonary cytokine-network and moreover has been described to act in the pulmonary host defense. This chapter gives an overview on the understanding of role of SP-A and SP-D in for human pulmonary disorders and points out the importance for pathology-orientated research to further elucidate the role of these molecules in adult lung diseases. As an outlook, it will become an issue of pulmonary pathology which might provide promising perspectives for applications in research, diagnosis and therapy (Awasthi 2010).

Biomarkers of therapeutic response in patients with chronic obstructive pulmonary disease: a critical review of the literature

Chronic obstructive pulmonary disease (COPD) is a leading cause of morbidity and mortality across the world. Unfortunately, none of the current therapies, except for smoking cessation and supplemental domiciliary oxygen for hypoxaemic patients, can modify its natural course or alter survival. The pipeline for new compounds is not very promising owing to repeated failures, and many large pharmaceutical companies have abandoned COPD drug discovery altogether. One major barrier to new drug discovery is the lack of modifiable biomarkers that can be used as surrogates of clinical outcomes such as exacerbation and mortality. The only accepted marker in COPD is forced expiratory volume in 1 second (FEV(1)). However, by definition, COPD is a non-reversible or poorly reversible condition with respect to FEV(1). Thus, very few drugs except for bronchodilators have been able to address this endpoint. Of many candidate molecules, sputum neutrophil counts, exhaled corrected alveolar nitric oxide and proline-glycine-proline (PGP) and N-α-PGP, which are breakdown products of collagen, are promising lung-based biomarkers. However, their clinical utility has not been validated in large clinical trials. Promising blood biomarkers include surfactant protein D, and pulmonary- and activation-regulated chemokine (PARC/CCL-18). However, the clinical data have been inconsistent. Non-specific inflammatory biomarkers such as C-reactive protein and interleukin-6 lack specificity for COPD and thus are of limited clinical usefulness.

Smoking reduces surfactant protein D and phospholipids in patients with and without chronic obstructive pulmonary disease

Background

Pulmonary surfactant D (SP-D) has important regulatory functions for innate immunity and has been implicated as a biomarker for chronic obstructive pulmonary disease (COPD). We hypothesized that COPD patients would have reduced bronchoalveolar lavage (BAL) fluid SP-D levels compared to healthy smoking and non-smoking controls.

Methods

BAL SP-D and phospholipids were quantified and corrected for dilution in 110 subjects (65 healthy never smokers, 23 smokers with normal spirometry, and 22 smokers with COPD).

Results

BAL SP-D was highest in never smokers (mean 51.9 μg/mL ± 7.1 μg/mL standard error) compared to both smokers with normal spirometry (16.0 μg/mL ± 11.8 μg/mL) and subjects with COPD (19.1 μg/mL ± 12.9 μg/mL; P < 0.0001). Among smokers with COPD, BAL SP-D correlated significantly with FEV₁% predicted (R = 0.43; P < 0.05); however, the strongest predictor of BAL SP-D was smoking status. BAL SP-D levels were lowest in current smokers (12.8 μg/mL ± 11.0 μg/mL), intermediate in former smokers (25.2 μg/mL ± 14.2 μg/mL; P < 0.008), and highest in never smokers. BAL phospholipids were also lowest in current smokers (6.5 nmol ± 1.5 nmol), intermediate in former smokers (13.1 nmol ± 2.1 nmol), and highest in never smokers (14.8 nmol ± 1.1 nmol; P < 0.0001).

Conclusions

These data suggest that smokers, and especially current smokers, exhibit significantly reduced BAL SP-D and phospholipids compared to nonsmokers. Our findings may help better explain the mechanism that leads to the rapid progression of disease and increased incidence of infection in smokers.

Biomarkers in COPD

Although there is increasing interest in using pulmonary biomarkers for a more complete and clinically relevant assessment of COPD and a plethora of biomarkers are becoming available, there is little information regarding their reproducibility and correlation with other outcome measurements in COPD. The lack of well-validated biomarkers that can be used for monitoring disease activity, predicting future clinical outcomes and the effect of therapeutic interventions highlights the factual need to identify new biomarkers in COPD. It is likely that, using what is called 'integrative functional informatics', which is a novel direction in the interfacing and integration of different technologies (genomics, proteomics, metabolomics and metabonomics, pharmacogenetics, and integrative approaches) for collection and analysis of data on biomarkers, we will be able to identify robust, reliable, and reproducible biomarkers in COPD.

Asthma and chronic obstructive pulmonary disease

PURPOSE OF REVIEW

In the clinical setting, patients who present with a combination of asthma and chronic obstructive pulmonary disease (COPD)-related traits are not uncommon. This review discusses recent advances in the characterization of the natural course, phenotypes, and molecular markers of cases with coexisting asthma and COPD and in the understanding of the nature of the link between these two conditions.

RECENT FINDINGS

Recent epidemiological evidence indicates that asthma accounts for a substantial proportion of cases of irreversible airflow limitation in the general population and that, in addition to the critical role of environmental exposures in adult age, alterations of developmental processes in childhood may also predispose patients with asthma to COPD later in life. Findings from clinical and experimental studies emphasize the existence of remarkable heterogeneity within the group of patients with coexisting asthma and COPD in terms of natural history of lung function, risk factors for disease progression, lung structural changes, and immunological profiles.

SUMMARY

The phenotypic complexity of cases with coexisting asthma and COPD challenges a rigid categorization of patients into existing diagnostic labels and suggests the importance of integrating clinical, functional, morphologic, immunological, and molecular assessments to tailor and optimize prevention and treatment.