Biomarkers for Chronic Obstructive Pulmonary Disease

Secondhand tobacco smoke and severity in wheezing children: Nasal oxidant stress and inflammation

OBJECTIVES

Prenatal and postnatal smoke exposures are associated with many lung diseases in children due to impaired lung function, increased inflammation, and oxidative stress. We aimed to determine the influence of secondhand tobacco smoke exposure on the levels of nasal glutathione, IL-8, IL-17, MMP-9, and TIMP-1, as well as serum surfactant protein-D (SP-D) in wheezy children.

METHODS

We enrolled 150 children with recurrent wheezing and recorded wheezing characteristics at enrollment. We measured the levels of serum cotinine, SP-D, nasal glutathione, IL-8, IL-17, MMP-9, and TIMP-1. Serum cotinine levels between 3 and 12 ng/mL, and above 12 ng/mL were defined as lower and higher level secondhand tobacco smoke exposure, respectively. The ANOVA test, Pearson's correlation analysis and multivariate analysis with a linear regression test were used for the statistical analysis.

RESULTS

Ninety-one children had been exposed to lower level secondhand tobacco smoke, while 24 children were exposed to higher level secondhand tobacco smoke. Thirty-five children were not exposed to cigarette smoke. Wheezing symptom scores were higher in exposed children (p = 0.03). Levels of other biomarkers showed no significant difference.

CONCLUSIONS

Secondhand tobacco smoke exposure is associated with more severe respiratory symptoms in wheezing children. However, levels of nasal or serum inflammatory markers fail to explain this association, either because of different mechanical factors in the process or due to low levels of the biomarkers especially in nasal secretions.

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.

Serum Metabolite Biomarkers Discriminate Healthy Smokers from COPD Smokers

COPD (chronic obstructive pulmonary disease) is defined by a fixed expiratory airflow obstruction associated with disordered airways and alveolar destruction. COPD is caused by cigarette smoking and is the third greatest cause of mortality in the US. Forced expiratory volume in 1 second (FEV1) is the only validated clinical marker of COPD, but it correlates poorly with clinical features and is not sensitive enough to predict the early onset of disease. Using LC/MS global untargeted metabolite profiling of serum samples from a well-defined cohort of healthy smokers (n = 37), COPD smokers (n = 41) and non-smokers (n = 37), we sought to discover serum metabolic markers with known and/or unknown molecular identities that are associated with early-onset COPD. A total of 1,181 distinct molecular ions were detected in 95% of sera from all study subjects and 23 were found to be differentially-expressed in COPD-smokers vs. healthy-smokers. These 23 putative biomarkers were differentially-correlated with lung function parameters and used to generate a COPD prediction model possessing 87.8% sensitivity and 86.5% specificity. In an independent validation set, this model correctly predicted COPD in 8/10 individuals. These serum biomarkers included myoinositol, glycerophopshoinositol, fumarate, cysteinesulfonic acid, a modified version of fibrinogen peptide B (mFBP), and three doubly-charged peptides with undefined sequence that significantly and positively correlate with mFBP levels. Together, elevated levels of serum mFBP and additional disease-associated biomarkers point to a role for chronic inflammation, thrombosis, and oxidative stress in remodeling of the COPD airways. Serum metabolite biomarkers offer a promising and accessible window for recognition of early-stage COPD.

Serum surfactant protein D is associated with the prognosis in patients with chronic kidney disease

BACKGROUND

Circulating surfactant protein D (SP-D) has been proved to be associated with cardiovascular disease and total mortality in European patients with coronary artery disease (CAD). This study was to determine whether serum SP-D levels are associated with 1-year prognosis in patients with chronic kidney disease (CKD) in a Chinese population.

METHODS

Serum SP-D levels were examined by ELISA kit in 264 patients undergoing coronary angiography. An estimated glomerular filtration rate (eGFR) was used to determine the presence of CKD. Gensini scores were calculated to reflect the severity of coronary lesions. The correlations between SP-D, Gensini scores, white blood cells, high-sensitivity C-reactive protein (hs-CRP) and eGFR were calculated. Patients with eGFR less than 60 ml/min per 1.73 m2 were followed up for an average of 14 months, and major adverse cardiac events (MACEs) were recorded and analyzed.

RESULTS

Patients with CKD compared with patients without CKD were more often men, with a higher prevalence of hypertension, CAD, average age, levels of fasting glucose, hs-CRP and SP-D (179.73 ± 72.80 versus 131.65 ± 94.29 ng/ml; all P < 0.05). Serum SP-D levels were positively correlated with Gensini scores and eGFR, but not with white blood cells or hs-CRP. CKD patients suffering from MACEs had higher levels of serum SP-D (217.02 ± 102.34 versus 172.26 ± 70.27 ng/ml) and patients with SP-D at least 200 ng/ml had higher risk of MACEs (all P < 0.05). Multivariable analysis showed that smoking, multivessel disease, CKD and SP-D (OR: 1.396, 95% CI: 1.058-2.718, P = 0.028) were associated with 1-year MACEs (all P < 0.05).

CONCLUSION

SP-D levels are associated with 1-year prognosis in patients with CKD.

Surfactant protein D, soluble intercellular adhesion molecule-1 and high-sensitivity C-reactive protein as biomarkers of chronic obstructive pulmonary disease

OBJECTIVE

The aim of this study was to estimate the serum levels of surfactant protein D (SP-D), soluble intercellular adhesion molecule-1 (sICAM-1), and high-sensitivity C-reactive protein (hs-CRP) in patients with chronic obstructive pulmonary disease (COPD) and to assess the correlation of these indices with COPD severity.

SUBJECTS AND METHODS

This analytic cross-sectional study was carried out on 64 COPD male patients, and 26 apparently healthy age-matched males as a control. Chest X-ray, spirometry and arterial blood gases were done for only COPD patients. Serum levels of SP-D, sICAM-1 and hs-CRP were determined by enzyme-linked immunosorbent assay in both patient and control groups.

RESULTS

The serum levels of SP-D, sICAM-1 and hs-CRP were significantly higher in COPD patients than controls (p < 0.001 for each). Also, these biomarkers were significantly higher in stages III and IV compared to either stage I or II (p < 0.01 for each). SP-D was significantly positively correlated with sICAM-1 and hs-CRP (r = 515, p < 0.001; r = 501, p < 0.001, respectively) and negatively correlated with PaO2 (r = -0.651, p < 0.001) and all parameters of spirometry.

CONCLUSION

SP-D, sICAM and hs-CRP were significantly higher in COPD patients in comparison with controls. Moreover, SP-D, sICAM-1, and hs-CRP were significantly negatively correlated with FEV1%. Accordingly, estimation of these biochemical indices may be used as biomarkers for assessment of COPD severity.

The expanding role of biomarkers in the assessment of smoking-related parenchymal lung diseases

Recent advances in the field of clinical biomarkers suggest that quantification of serum proteins could play an important role in the diagnosis, classification, prognosis, and treatment response of smoking-related parenchymal lung diseases. COPD and idiopathic pulmonary fibrosis (IPF), two common chronic progressive parenchymal lung diseases, share cigarette smoke exposure as a common dominant risk factor for their development. We have recently shown that COPD and interstitial lung disease may represent distinct outcomes of chronic tobacco use, whereas others have demonstrated that both diseases coexist in some individuals. In this perspective, we examine the potential role of peripheral blood biomarkers in predicting which individuals will develop COPD or IPF, as well as their usefulness in tracking disease progression and exacerbations. Additionally, given the current lack of sensitive and effective metrics to determine an individual's response to treatment, we evaluate the potential role of biomarkers as surrogate markers of clinical outcomes. Finally, we examine the possibility that changes in levels of select protein biomarkers can provide mechanistic insight into the common origins and unique individual susceptibilities that lead to the development of smoking-related parenchymal lung diseases. This discussion is framed by a consideration of the properties of ideal biomarkers for different clinical and research purposes and the best uses for those biomarkers that have already been proposed and investigated.

Insight into the dynamic interaction of different carbohydrates with human surfactant protein D: molecular dynamics simulations

The unbinding process of three monosaccharides--galactose, glucose, and mannose--from human surfactant protein D (hSP-D) was investigated by the molecular docking and molecular dynamics methods to explore the cause of different dynamic interaction between these monosaccharides and the protein. The results show that the low affinity of galactose for hSP-D is attributed to the different binding conformation from the other two monosaccharides. The sugar coordinates to the calcium ion by the hydroxyl groups in the C2 and C3 atoms, so it cannot form the effective interaction with hSP-D. Glucose and mannose have similar binding conformations with hSP-D. Their difference in the affinity is induced by the interaction between the hydroxyl group in the C2 atom and the residue Asp325. The direction of the hydroxyl group in mannose results in the formation of the hydrogen bond with Asp325 and further makes mannose hydrogen-bond to the residues Glu329 and Arg343 by the hydroxyl groups in the C3, C4, and C6 atoms. As glucose only forms three hydrogen bonds with the residues Glu321, Asn323, and Glu329 by the hydroxyl groups in the C3 and C4 atoms, its interaction with hSP-D is weaker than that of mannose. Thus glucose has a lower energy barrier of dissociation. This work could provide the more penetrating understanding of hSP-D physiological functions.

Polymorphisms in surfactant protein-D are associated with chronic obstructive pulmonary disease

Chronic obstructive pulmonary disease (COPD) is characterized by alveolar destruction and abnormal inflammatory responses to noxious stimuli. Surfactant protein-D (SFTPD) is immunomodulatory and essential to host defense. We hypothesized that polymorphisms in SFTPD could influence the susceptibility to COPD. We genotyped six single-nucleotide polymorphisms (SNPs) in surfactant protein D in 389 patients with COPD in the National Emphysema Treatment Trial (NETT) and 472 smoking control subjects from the Normative Aging Study (NAS). Case-control association analysis was performed using Cochran-Armitage trend tests and multivariate logistic regression. The replication of significant associations was attempted in the Boston Early-Onset COPD Study, the Evaluation of COPD Longitudinally to Identify Predictive Surrogate Endpoints (ECLIPSE) Study, and the Bergen Cohort. We also correlated SFTPD genotypes with serum concentrations of surfactant protein-D (SP-D) in the ECLIPSE Study. In the NETT-NAS case-control analysis, four SFTPD SNPs were associated with susceptibility to COPD: rs2245121 (P = 0.01), rs911887 (P = 0.006), rs6413520 (P = 0.004), and rs721917 (P = 0.006). In the family-based analysis of the Boston Early-Onset COPD Study, rs911887 was associated with prebronchodilator and postbronchodilator FEV(1) (P = 0.003 and P = 0.02, respectively). An intronic SNP in SFTPD, rs7078012, was associated with COPD in the ECLIPSE Study and the Bergen Cohort. Multiple SFTPD SNPs were associated with serum SP-D concentrations in the ECLIPSE Study. We demonstrated an association of polymorphisms in SFTPD with COPD in multiple populations. We demonstrated a correlation between SFTPD SNPs and SP-D protein concentrations. The SNPs associated with COPD and SP-D concentrations differed, suggesting distinct genetic influences on susceptibility to COPD and SP-D concentrations.