Serum surfactant protein-A, but not surfactant protein-D or KL-6, can predict preclinical lung damage induced by smoking

Immature Surfactant Protein Type B and Surfactant Protein Type D Correlate with Coronary Heart Disease in Patients with Type 2 Diabetes

BACKGROUND

Different specific surfactant proteins (SPs) have been associated with various pathological conditions, not only of the respiratory system, but also more recently with cardiovascular diseases, such as heart failure. The aim of the present study was to evaluate the role of SP-A, SP-D, and the precursor protein of SP-B (proSP-B) in the pathogenesis of cardiovascular damage in patients affected by type 2 diabetes (T2D).

METHODS

The study considered 31 patients with T2D (DN group), 34 patients with both T2D and coronary heart disease (CHD) (DC group), and 30 patients without diabetes but with a diagnosis of CHD (NC group). SP-A, SP-D, and proSP-B concentrations were determined in plasma samples, and were statistically compared using parametric and multivariate methods.

RESULTS

Higher plasma concentrations of SP-D and proSP-B were found in patients affected by both T2D and CHD (DC group), and in patients with CHD without diabetes (NC group), in comparison to T2D patients (DN group). A significant correlation, both with linear regression (r = 0.3565, p = 0.001) and Principal Component Analysis (PCA), was found between the plasma levels of SP-D and proSP-B in the overall cohort of patients. No differences in SP-A were observed among the three groups of subjects.

CONCLUSION

The present study extends the knowledge on the role of plasma SPs' levels as possible indicators of the risk of CHD being linked to T2D disease progression.

Krebs von den lungen-6 as a clinical marker for hypersensitivity pneumonitis: A meta-analysis and bioinformatics analysis

Aim

Hypersensitivity pneumonitis (HP), also referred to as exogenous allergic alveolitis, is one of the most common interstitial lung diseases (ILDs). A potential immune biomarker, Krebs von den lgen-6 (KL-6) characterizes the progression and severity of HP. The meta-analysis in this study was conducted to elucidate the variations in the concentrations of KL-6 in different types of HP.

Methods

A systematic search of various databases such as EMBASE, Pubmed, CNKI, VIP, Web of Science, and WanFang was carried out to find relevant published articles between January 1980 and August 2022 that explored the relationship between KL-6 and allergic pneumonia. Standardized mean difference (SMD) and 95% confidence interval (CI) were used as effect sizes for comparison among different groups. The GSE47460 and GSE150910 datasets were downloaded to extract and validate the differences in KL-6 mRNA expression between HP lung tissue and healthy controls. Furthermore, the single-cell sequencing dataset GSE135893 was downloaded to extract KL-6 mRNA expression in type II alveolar epithelial cells to validate the differences between HP and healthy controls. Two researchers evaluated the quality of the included studies by employing Newcastle-Ottawa Scale. All the qualified studies were subjected to statistical analyses carried out utilizing RevMan 5.2, Stata 11.0, and R software 4.1.3.

Results

Twenty studies aligned perfectly with the inclusion criteria of the meta. The concentrations of KL-6 were substantially higher in the blood of HP patients as compared to the control group. Subgroup analyses were carried out in accordance with the allergen source and the results revealed that patients with different allergens had higher blood KL-6 concentrations than healthy controls. Additionally, different subgroups of subjects were created for meta-analysis as per the fibrosis status, race, measurement method, and sample type. The concentration of KL-6 in blood was much higher in all HP subgroups than in healthy control groups. Moreover, the bioinformatics analysis revealed that KL-6 mRNA expression was higher in HP lung tissue and type II alveolar epithelial cells as compared to healthy controls.

Conclusion

The present meta-analysis and bioinformatics analysis suggested that the concentration levels of KL-6 varied between HP patients and healthy individuals, and the KL-6 concentrations may be higher in the blood samples of HP patients.

Systematic review registration

https://www.crd.york.ac.uk/prospero/, CRD42022355334.

Different expression of circulating microRNA profile and plasma SP-D in Tibetan COPD patients

COPD is the fourth leading cause of mortality, and is predicted to be the third leading cause of death worldwide by 2020. But few studies on Tibetan COPD of China. This study identifies distinctive miRNA signatures in Tibetan COPD patients from Tibetan healthy subjects that could serve as diagnostic biomarkers or describe differential molecular mechanisms with potential therapeutic implications. In this study, a total of 210 differentially expressed miRNAs were screened. Analysis of the functions of target genes of differentially expressed miRNAs via GO enrichment analysis revealed that they mainly influenced guanyl-nucleotide exchange factor activity, cell morphogenesis and the positive regulation of GTPase activity. KEGG pathway enrichment analysis showed that these target genes were mainly enriched in signaling by NGF, Axon guidance, developmental biology, ubiquitin mediated proteolysis, and PDGF signaling pathways. MiR-106-5p and miR-486-5p expression was validated in the complete cohort. Age, plasma miR-106-5p, miR-486-5p, SP-D protein levels, and SP-D mRNA level were also determined to be correlated with FEV1%Pred, and may as the risk factors of Tibetan COPD. The combination of plasma miR-106-5p, miR-486-5p and SP-D mRNA expression may be the best model to assist the diagnosis of Tibetan COPD.

Pulmonary hypertension and chronic lung disease: where are we headed?

Pulmonary hypertension related to chronic lung disease, mainly represented by COPD and idiopathic pulmonary fibrosis, is associated with a worse outcome when compared with patients only affected by parenchymal lung disease. At present, no therapies are available to reverse or slow down the pathological process of this condition and most of the clinical trials conducted to date have had no clinically significant impact. Nevertheless, the importance of chronic lung diseases is always more widely recognised and, along with its increasing incidence, associated pulmonary hypertension is also expected to be growing in frequency and as a health burden worldwide. Therefore, it is desirable to develop useful and reliable tools to obtain an early diagnosis and to monitor and follow-up this condition, while new insights in the therapeutic approach are explored.

Damage-Associated Molecular Patterns and Myeloid-Derived Suppressor Cells in Bronchoalveolar Lavage Fluid in Chronic Obstructive Pulmonary Disease Patients

Myeloid-derived suppressor cells (MDSCs) are present in the human lung microenvironment, and they may be involved in the local inflammatory process in chronic obstructive pulmonary disease (COPD). Chronic inflammation in COPD may induce immunogenic cell death of structural airway cells, causing the release of damage-associated molecular patterns (DAMPs). DAMPs may activate the innate and adaptive immune system. The relationship between MDSCs and DAMPs in COPD is poorly described in the available literature. Objectives. (1) Assessment of MDSC percentage and DAMP concentration in bronchoalveolar lavage fluid (BALF) and peripheral blood. (2) Analysis of the relationship between MDSC percentage and chosen DAMPs. Patients and Methods. 30 COPD patients were included. Using monoclonal antibodies directly conjugated with fluorochromes in flow cytometry, MDSCs were assessed in BALF and peripheral blood. The concentration of DAMPs was estimated using sandwich ELISA. Using the Bradford method, the total protein concentrations were evaluated. Results. The percentage of MDSCs among MC in BALF correlated well with the concentration of defensin and heat shock protein 27. Assessing the percentage of MDSCs among all leukocytes in BALF, we revealed a significant correlation with the concentration of defensin, hyaluronic acid, and surfactant protein A. No dependencies occurred between DAMPs and MDSCs in peripheral blood. Conclusion. MDSCs and DAMPs occur in the COPD patient lung microenvironment. Significant correlations between them found in BALF may indicate their influence on the local inflammatory process in COPD. These relationships allow better understanding of the inflammatory process in COPD.

Drug-induced interstitial lung disease in the treatment of malignant lymphoma as a potential diagnostic marker: a comparison of serum Krebs von Lungen-6 and thymus and activation-regulated chemokine/CC chemokine ligand 17

Purpose

Cure-oriented treatment of malignant lymphoma (ML) is possible even in an advanced stage; however, the progression of drug-induced interstitial lung disease (DILD) sometimes accounts for poor clinical outcomes. This study aims to assess the incidence and clinical characteristics of DILD among patients with ML and compares the serum level of Krebs von den Lungen-6 (KL-6) with that of circulating thymus and activation-regulated chemokine (TARC)/CC chemokine ligand 17 (CCL17) as a diagnostic biomarker for DILD.

Patients and methods

Between July 2011 and August 2016, we enrolled 36 patients with ML who were undergoing systemic chemotherapy at our hospital. Then, we evaluated the serum concentration of KL-6 and TARC/CCL17 by a sandwich-type electrochemiluminescence immunoassay and enzyme-linked immunosorbent assay, respectively.

Results

DILD developed in 22.2% of patients with ML. All patients recovered immediately after the discontinuation of causative drug and/or glucocorticoid therapy. Although the sensitivity of both TARC/CCL17 and KL-6 was almost equal, the mean concentration of serum KL-6 after the progression of interstitial lung disease was significantly higher than that before progression.

Conclusion

DILD developed in patients who were treated with first-line rituximab combined regimen. Remarkably, TARC/CCL17 and KL-6 seemed approximately equal as a predictive biomarkers for DILD; however, KL-6 was more specific than TARC/CCL17.

Surfactant proteins changes after acute hemodynamic improvement in patients with advanced chronic heart failure treated with Levosimendan

Alveolar-capillary membrane evaluated by carbon monoxide diffusion (DLCO) plays an important role in heart failure (HF). Surfactant Proteins (SPs) have also been suggested as a worthwhile marker. In HF, Levosimendan improves pulmonary hemodynamics and reduces lung fluids but associated SPs and DLCO changes are unknown. Sixty-five advanced HF patients underwent spirometry, cardiopulmonary exercise test (CPET) and SPs determination before and after Levosimendan. Levosimendan caused natriuretic peptide-B (BNP) reduction, peakVO₂ increase and VE/VCO₂ slope reduction. Spirometry improved but DLCO did not. SP-A, SP-D and immature SP-B reduced (73.7 ± 25.3 vs. 66.3 ± 22.7 ng/mL*, 247 ± 121 vs. 223 ± 110 ng/mL*, 39.4 ± 18.7 vs. 34.4 ± 17.9AU*, respectively); while mature SP-B increased (424 ± 218 vs. 461 ± 243 ng/mL, * = p < 0.001). Spirometry, BNP and CPET changes suggest hemodynamic improvement and lung fluid reduction. SP-A, SP-D and immature SP-B reduction indicates a reduction of inflammatory stress; conversely mature SP-B increase suggests alveolar cell function restoration. In conclusion, acute lung fluid reduction is associated with SPs but not DLCO changes. SPs are fast responders to alveolar-capillary membrane condition changes.

Surfactant Protein D in Respiratory and Non-Respiratory Diseases

Surfactant protein D (SP-D) is a multimeric collectin that is involved in innate immune defense and expressed in pulmonary, as well as non-pulmonary, epithelia. SP-D exerts antimicrobial effects and dampens inflammation through direct microbial interactions and modulation of host cell responses via a series of cellular receptors. However, low protein concentrations, genetic variation, biochemical modification, and proteolytic breakdown can induce decomposition of multimeric SP-D into low-molecular weight forms, which may induce pro-inflammatory SP-D signaling. Multimeric SP-D can decompose into trimeric SP-D, and this process, and total SP-D levels, are partly determined by variation within the SP-D gene, SFTPD. SP-D has been implicated in the development of respiratory diseases including respiratory distress syndrome, bronchopulmonary dysplasia, allergic asthma, and chronic obstructive pulmonary disease. Disease-induced breakdown or modifications of SP-D facilitate its systemic leakage from the lung, and circulatory SP-D is a promising biomarker for lung injury. Moreover, studies in preclinical animal models have demonstrated that local pulmonary treatment with recombinant SP-D is beneficial in these diseases. In recent years, SP-D has been shown to exert antimicrobial and anti-inflammatory effects in various non-pulmonary organs and to have effects on lipid metabolism and pro-inflammatory effects in vessel walls, which enhance the risk of atherosclerosis. A common SFTPD polymorphism is associated with atherosclerosis and diabetes, and SP-D has been associated with metabolic disorders because of its effects in the endothelium and adipocytes and its obesity-dampening properties. This review summarizes and discusses the reported genetic associations of SP-D with disease and the clinical utility of circulating SP-D for respiratory disease prognosis. Moreover, basic research on the mechanistic links between SP-D and respiratory, cardiovascular, and metabolic diseases is summarized. Perspectives on the development of SP-D therapy are addressed.

Molecules of Damage-Associated Patterns in Bronchoalveolar Lavage Fluid and Serum in Chronic Obstructive Pulmonary Disease

Chronic exposure to detrimental environmental factors may induce immunogenic cell death of structural airway cells in chronic obstructive pulmonary disease (COPD). Damage-associated molecular patterns (DAMPs) is a family of heterogeneous molecules released from injured or dead cells, which activate innate and adaptive immune responses on binding to the pattern recognition receptors on cells. This study seeks to define the content of DAMPs in the bronchoalveolar lavage fluid (BALF) and serum of COPD patients, and the possible association of these molecules with clinical disease features. Thirty COPD in advanced disease stages were enrolled into the study. Pulmonary function tests, arterial blood gas content, 6-minute walk test, and BODE index were assessed. The content of DAMPs was estimated using the commercial sandwich-ELISA kits. We found differential alterations in the content of various DAMP molecules. In the main, BALF DAMPs positively associated with age, forced expiratory volume in one second (FEV1), and residual volume (RV); and inversely with PaO₂, residual volume/total lung capacity (RV/TLC) ratio, and the disease severity staging. In serum, DAMPS positively associated with the intensity of smoking and inversely with age, PaO₂, and TLC. In conclusion, DAMPs are present in both BALF and serum of COPD patients, which points to enhanced both local in the lung environment as well as systemic pro-inflammatory vein in this disease. These molecules appear involved with the lung damage and clinical variables featuring COPD. However, since the involvement of various DAMPs in COPD is variable, the exact role they play is by far unsettled and is open to further exploration.

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 ).

Diving and pulmonary physiology: Surfactant binding protein, lung fluid and cardiopulmonary test changes in professional divers

Alteration of breathing pattern ranging from an increase of respiratory rate to overt hyperventilation during and after SCUBA diving is frequently reported and is associated with intrathoracic fluid overload. This study was undertaken to assess breathing efficiency after diving and the association with damage of alveolar cells. Ventilation efficiency (VE/VCO₂) during maximal cardiopulmonary exercise test (CPET) before and 2h after a standard protocol dive has been analyzed in twelve professional males divers (39.5±10.5years). Furthermore, within 30min from surfacing, subjects underwent blood sample for surfactant derived proteins (SPs) determination, while thoracic ultrasound was performed at 30, 60, 90 and 120min. Dive consisted in a single quick descend to 18m of sea water, a 47min bottom stay and a direct ascent to the surface. CPET showed a preserved exercise performance with an increase of VE/VCO₂ after diving (21.4±2.9 vs. 22.9±3.3, p<0.05). Mature SP-B increased while other SPs were unchanged. Ultrasound lung comets (ULC) were high in the first post-dive evaluation with a significant, but not complete, progressive reduction at 120min after surfacing. In conclusion we showed that, after a single dive, lung fluid increased with an increase of ventilation inefficiency and of the mature form of SP-B.

Surfactant protein B: From biochemistry to its potential role as diagnostic and prognostic marker in heart failure

Growing interest raised on circulating biomarkers of structural alveolar-capillary unit damage and very recent data support surfactant protein type B (SP-B) as the most promising candidate in this setting. With respect to other proteins proposed as possible markers of lung damage, SP-B has some unique qualities: it is critical for the assembly of pulmonary surfactant, making its lack incompatible with life; it has no other known site of synthesis except alveolar epithelial cells different from other surfactant proteins; and, it undergoes a proteolytic processing in a pulmonary-cell-specific manner. In the recent years circulating SP-B isoforms, mature or immature, have been demonstrated to be detectable in the circulation depending on the magnitude of the damage of alveolar capillary membrane. In the present review, we summarize the recent knowledge on SP-B regulation, function and we discuss its potential role as reliable biological marker of alveolar capillary membrane (dys)function in the context of heart failure.

Serum Levels of Surfactant Proteins in Patients with Combined Pulmonary Fibrosis and Emphysema (CPFE)

Introduction

Emphysema and idiopathic pulmonary fibrosis (IPF) present either per se or coexist in combined pulmonary fibrosis and emphysema (CPFE). Serum surfactant proteins (SPs) A, B, C and D levels may reflect lung damage. We evaluated serum SP levels in healthy controls, emphysema, IPF, and CPFE patients and their associations to disease severity and survival.

Methods

122 consecutive patients (31 emphysema, 62 IPF, and 29 CPFE) and 25 healthy controls underwent PFTs, ABG-measurements, 6MWT and chest HRCT. Serum levels of SPs were measured. Patients were followed-up for 1-year.

Results

SP-A and SP-D levels differed between groups (p = 0.006 and p<0.001 respectively). In post-hoc analysis, SP-A levels differed only between controls and CPFE (p<0.05) and CPFE and emphysema (p<0.05). SP-D differed between controls and IPF or CPFE (p<0.001 for both comparisons). In IPF SP-B correlated to pulmonary function while SP-A, correlated to the Composite Physiological Index (CPI). Controls current smokers had higher SP-A and SP-D levels compared to non-smokers (p = 0.026 and p = 0.023 respectively). SP-D levels were higher in CPFE patients with extended emphysema (p = 0.042). In patients with IPF, SP-B levels at the upper quartile of its range (≥26 ng/mL) presented a weak association with reduced survival (p = 0.05).

Conclusion

In conclusion, serum SP-A and SP-D levels were higher where fibrosis exists or coexists and related to disease severity, suggesting that serum SPs relate to alveolar damage in fibrotic lungs and may reflect either local overproduction or overleakage. The weak association between high levels of SP-B and survival needs further validation in clinical trials.

Circulating thymus and activation-regulated chemokine/CC chemokine ligand 17 is a strong candidate diagnostic marker for interstitial lung disease in patients with malignant tumors: a result from a pilot study

Introduction

Serum Krebs von den Lungen-6 (KL-6) level is an established diagnostic marker of interstitial lung disease (ILD). However, it is also elevated in patients with non-small cell lung cancer (NSCLC). The significance of circulating thymus and activation-regulated chemokine (TARC)/CC chemokine ligand 17 (CCL17) in malignant diseases remains unknown.

Methods

We measured circulating TARC/CCL17 and KL-6 using enzyme-linked immunosorbent assay and electrochemiluminescence immunoassay, respectively, in 26 patients with malignant disease and six patients with benign lung disease (BLD). The cutoff levels were 500 U/mL for KL-6 and 450 pg/mL for TARC/CCL17. The significance of the markers was evaluated in relationship to the presence of ILD (n=10). The statistical significance was set at P<0.05.

Results

The KL-6 positive ratio was significantly higher in the patients with NSCLC (n=17) than in those with BLD. There was a significant difference in the KL-6 positive ratio between the patients with NSCLC without ILD and those with BLD without ILD. However, there were no significant differences in the TARC/CCL17 positive ratio between the patients with NSCLC and BLD or between those with NSCLC without ILD and those with BLD without ILD. The TARC/CCL17 positive ratio was significantly higher in the patients with malignancy and ILD than in those without ILD. There was also a significant difference in the TARC/CCL17 positive ratio between the patients with NSCLC without ILD and those with ILD.

Conclusion

TARC/CCL17 may be useful for the diagnosis of ILD in patients with malignancies. Confirmation of the results is warranted through a large-scale study.

Surfactant-derived proteins as markers of alveolar membrane damage in heart failure

Background

In heart failure (HF) alveolar-capillary membrane is abnormal. Surfactant-derived proteins (SPs) and plasma receptor for advanced-glycation-end-products (RAGE) have been proposed as lung damage markers.

Methods

Eighty-nine chronic HF and 17 healthy subjects were evaluated by echocardiography, blood parameters, carbon monoxide lung diffusion (DLCO) and cardiopulmonary exercise test. We measured immature SP-B, mature SP-B, SP-A, SP-D and RAGE plasma levels.

Results

Immature SP-B (arbitrary units), mature SP-A (ng/ml) and SP-D (ng/ml), but not mature SP-B (ng/ml) and RAGE (pg/ml) levels, were higher in HF than in controls [immature SP-B: 15.6 (13.1, 75^th–25^th interquartile range) Vs. 11.1 (6.4), p<0.01; SP-A, 29.6 (20.1) Vs. 18.3 (13.5), p = 0.01; SP-D: 125 (90) Vs. 78 (58), p<0.01]. Immature SP-B, SP-A, SP-D and RAGE values were related to DLCO, peak oxygen consumption, ventilatory efficiency, and brain natriuretic peptide (BNP), whereas plasma mature SP-B was not. The DLCO Vs. immature SP-B correlation was the strongest one. At multivariate analysis, RAGE was associated to age and creatinine, SP-A to DLCO and BNP, SP-D to BNP, mature SP-B to DLCO and creatinine, and immature SP-B only but strongly to DLCO.

Conclusions

Immature SP-B is the most reliable biological marker of alveolar-capillary membrane function in HF.

Surfactant protein D, Club cell protein 16, Pulmonary and activation-regulated chemokine, C-reactive protein, and Fibrinogen biomarker variation in chronic obstructive lung disease

Chronic obstructive pulmonary disease (COPD) is a multifaceted condition that cannot be fully described by the severity of airway obstruction. The limitations of spirometry and clinical history have prompted researchers to investigate a multitude of surrogate biomarkers of disease for the assessment of patients, prediction of risk, and guidance of treatment. The aim of this review is to provide a comprehensive summary of observations for a selection of recently investigated pulmonary inflammatory biomarkers (Surfactant protein D (SP-D), Club cell protein 16 (CC-16), and Pulmonary and activation-regulated chemokine (PARC/CCL-18)) and systemic inflammatory biomarkers (C-reactive protein (CRP) and fibrinogen) with COPD. The relevance of these biomarkers for COPD is discussed in terms of their biological plausibility, their independent association to disease and hard clinical outcomes, their modification by interventions, and whether changes in clinical outcomes are reflected by changes in the biomarker.

Factors influencing the measurement of plasma/serum surfactant protein D levels by ELISA

Background

Extensive variations in human surfactant protein D (SP-D) levels in circulation as measured by ELISA exist in the published literature. In order to determine the source of these variations, factors influencing the measurement by ELISA were explored.

Materials and Methods

Peripheral blood from healthy individuals was collected into various vacutainers during the same blood draw. Recombinant SP-D was diluted into different matrices and used for a standard curve. Samples were analyzed by capture ELISA using one of two distinct detection antibodies.

Results

The type of matrix had some effects on detection of recombinant SP-D. The type of anticoagulant used and dilution factor had very little effect, except for in plasma collected in EDTA vacutainers. The extent of variation in published values seemed to be due to the ELISA configuration employed, and, in agreement with this, we found that by switching the detection antibody, there was a 50% decrease in the extrapolated SP-D value of serum and plasma samples. Storage of samples resulted in slight changes in measured SP-D levels.

Conclusions

The ELISA configuration employed to measure circulating levels of SP-D has a significant effect on the extrapolated values. In both configurations tested, the use of EDTA as a coagulant resulted in inconsistent values, and we, therefore, suggest the avoidance of this anticoagulant when assaying for SP-D by ELISA. While the demonstrated effects of several factors on measurement of SP-D may not account for all the disparities amongst the previous studies, they stress that variations in methodologies for measuring the same protein can result in very inconsistent results.

The role of Tc-99m DTPA aerosol scintigraphy in the differential diagnosis of COPD and asthma

OBJECTIVE

Chronic obstructive lung disease (COPD) and asthma are characterized as similar to each other in causing airway obstruction and being an inflammatory process. The purpose of this study was to investigate whether technetium-99m diethylenetriaminepentaacetic acid ((99m) Tc-DTPA) aerosol scintigraphy could be used in the differential diagnosis of asthma and COPD.

METHODS

Eighty-four patients (male/female: 32/52; mean age 50.2 ± 12.7 years) with obstructive lung disease and 30 healthy volunteers as the control group were enrolled in the study. The patients were divided into two groups as COPD and asthma and also smoking subgroups. Alveolar clearance study was performed using a radiolabeled aerosol of (99m) Tc-DTPA. Mucociliary clearance was evaluated with T½ , cap value and penetration index parameters. All patient underwent pulmonary function tests and Forced expiratory volume (FEV1 ), forced vital capacity (FVC) and FEV1 /FVC parameters were obtained.

RESULTS

The mean of T½ values of (99m) Tc-DTPA aerosol and FEV1 /FVC value among spirometric tests of the nonsmoking COPD patients were significantly lower than nonsmoking asthma patients (46.1 ± 14.3, 62.3 ± 18.7, P = 0.02; 65.2 ± 10.8, 81.4 ± 16.5, P = 0.04, respectively). The cap value was significantly higher in nonsmoking COPD patients (1.21 ± 0.49, 0.76 ± 0.22, P = 0.03). While there were no statistically and significantly different between control and asthmatic groups at the scintigraphic parameters and spirometric parameters, the mean of T½ values, cap value and spirometric parameters were statistically different between control and COPD groups (P < 0.05).

CONCLUSION

We showed that assessment of mucociliary permeability with (99m) Tc-DTPA aerosol scintigraphy was a useful, easy to apply and a noninvasive technique to use in the differential diagnosis of nonsmoker COPD and asthma.

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).

Genetic variant associations of human SP-A and SP-D with acute and chronic lung injury

Pulmonary surfactant, a lipoprotein complex, maintains alveolar integrity and plays an important role in lung host defense, and control of inflammation. Altered inflammatory processes and surfactant dysfunction are well described events that occur in patients with acute or chronic lung disease that can develop secondary to a variety of insults. Genetic variants of surfactant proteins, including single nucleotide polymorphisms, haplotypes, and other genetic variations have been associated with acute and chronic lung disease throughout life in several populations and study groups. The hydrophilic surfactant proteins SP-A and SP-D, also known as collectins, in addition to their surfactant-related functions, are important innate immunity molecules as these, among others, exhibit the ability to bind and enhance clearance of a wide range of pathogens and allergens. This review focuses on published association studies of human surfactant proteins A and D genetic polymorphisms with respiratory, and non-respiratory diseases in adults, children, and newborns. The potential role of genetic variations in pulmonary disease or pathogenesis is discussed following an evaluation, and comparison of the available literature.

Circulating markers of interstitial lung disease and subsequent risk of lung cancer

BACKGROUND

Inflammation and pulmonary diseases, including interstitial lung diseases, are associated with increased lung cancer risk. Circulating levels of surfactant protein-D (SP-D) and Krebs von Lungren-6 (KL-6) are elevated in interstitial lung disease patients and may be useful markers of processes contributing to lung cancer.

METHODS

We conducted a nested case-control study, including 532 lung cancer cases, 582 matched controls, and 150 additional controls with chest X-ray (CXR) evidence of pulmonary scarring, in the Prostate, Lung, Colorectal and Ovarian Cancer Screening Trial. Serum SP-D and KL-6 levels were measured using enzyme immunoassay. Logistic regression was used to estimate the associations of SP-D and KL-6 with lung cancer and CXR scarring.

RESULTS

Cases had higher levels than controls for SP-D (median 118.7 vs. 105.4 ng/mL, P = 0.008) and KL-6 (372.0 vs. 325.8 μg/mL, P = 0.001). Lung cancer risk increased with SP-D (P(trend) = 0.0003) and KL-6 levels (P(trend) = 0.005). Compared with the lowest quartile, lung cancer risk was elevated among those with the highest quartiles of SP-D (OR = 1.87, 95% CI: 1.32-2.64) or KL-6 (OR = 1.58, 95% CI: 1.11-2.25). Among controls, participants with CXR scarring were more likely than those without scarring to have elevated levels of SP-D (quartile 4 vs. quartile 1: OR = 1.67, 95% CI: 1.04-2.70, P(trend) = 0.05) but not of KL-6 (OR = 1.04, 95% CI: 0.64-1.68, P(trend) = 0.99).

CONCLUSION

Circulating levels of SP-D and KL-6 are associated with subsequent lung cancer risk.

IMPACT

Our findings support a potential role for interstitial lung disease in lung cancer etiology or early detection, but additional research is needed.

Ageing and long-term smoking affects KL-6 levels in the lung, induced sputum and plasma

Background

KL-6 is a high-molecular-weight glycoprotein classified as a human MUC1 mucin. It was hypothesized that KL-6 could be detectable in the circulating blood and especially in airway secretions in lung diseases associated with mucus production such as chronic obstructive pulmonary disease (COPD). Additional aims of this study were to investigate whether the levels of KL-6 in plasma and sputum are related to ageing and smoking history.

Methods

The concentrations of KL-6 in plasma and induced sputum supernatants from young and/or middle aged/elderly non-smokers, smokers and patients with COPD were assayed by ELISA (n = 201). The subjects were classified into five groups according to age, smoking status and presence of COPD. In addition, KL-6 expression in control and diseased lung i.e. samples from patients with COPD (n = 28), were analyzed by immunohistochemistry and digital image analysis.

Results

The plasma levels of KL-6 increased with age both in non-smokers and smokers. Among middle aged/elderly subjects, plasma KL-6 levels in all smokers regardless of COPD were significantly higher than in non-smokers, whereas sputum levels of KL-6 were significantly higher in COPD compared not only to non-smokers but also to smokers. KL-6 was more prominently expressed in the bronchiolar/alveolar epithelium in COPD than in the control lungs. Plasma and sputum KL-6 levels correlated inversely with obstruction and positively with smoking history and ageing. The linear multiple regression analysis confirmed that age and cigarette smoking had independent effects on plasma KL-6.

Conclusions

KL-6 increases with ageing and chronic smoking history, but prospective studies will be needed to elucidate the significance of KL-6 in chronic airway diseases.

Ageing and smoking contribute to plasma surfactant proteins and protease imbalance with correlations to airway obstruction

BACKGROUND

A significant number of young people start smoking at an age of 13-15, which means that serious smoking-evoked changes may have been occurred by their twenties. Surfactant proteins (SP) and matrix metalloproteinases (MMPs) and their tissue inhibitors (TIMPs) have been linked to cigarette smoke induced lung remodelling and chronic obstructive pulmonary disease (COPD). However, the level of these proteins has not been examined during ageing or in young individuals with short smoking histories.

METHODS

Plasma levels of SP-A, SP-D, MMP-9, and TIMP-1 were measured by EIA/ELISA from young (18-23 years) non-smoking controls (YNS) (n = 36), smokers (YS) (n = 51), middle aged/elderly (37-77 years) non-smoking controls (ONS) (n = 40), smokers (OS) (n = 64) (FEV1/FVC >0.7 in all subjects) and patients with COPD (n = 44, 35-79 years).

RESULTS

Plasma levels of SP-A increased with age and in the older group in relation to smoking and COPD. Plasma SP-D and MMP-9 levels did not change with age but were elevated in OS and COPD as compared to ONS. The TIMP-1 level declined with age but increased in chronic smokers when compared to ONS. The clearest correlations could be detected between plasma SP-A vs. age, pack years and FEV1/FVC. The receiver operating characteristic (ROC) curve analysis revealed SP-A to be the best marker for discriminating between patients with COPD and the controls (area under ROC curve of 0.842; 95% confidence interval, 0.785-0.899; p < 0.001).

CONCLUSIONS

Age has a significant contribution to potential markers related to smoking and COPD; SP-A seems to be the best factor in differentiating COPD from the controls.

Circulating biomarkers of hazard effects from cigarette smoking

Smoking, leading to over 438,000 annual deaths in the US and 92 billion US dollars in lost productivity, is an important risk factor for several diseases. Global smoking statistics for 2002 have shown that 80,000 to 100,000 children worldwide start smoking every day. Human biomonitoring nowadays has provided an efficient and cost-effective means of measuring human exposures and biological effects of smoking. To review the utility of biomarkers in reflecting the hazard from cigarette smoking, we comprehensively searched the Cochrane Library, Medline and EMbase from 1966 to May 2010 with the language limit of English. We found that the currently used biomarkers, such as tobacco-specific metabolites, smoking-induced genotoxic products, may not scientifically reflect the hazard from cigarette smoking. More research is needed to find out more effective biomarkers for estimating hazards from cigarette smoking. This paper is expected to help researchers understand the current utilization of biomarkers related to cigarette smoking and to provide suggestive guides to tobacco companies in producing less-toxic cigarettes, thus to provide a safe way to smoke.

Pneumoproteins and inflammatory biomarkers in asphalt pavers

Pneumoproteins, biomarkers of systemic inflammation and endothelial activation were studied across a season in 72 asphalt pavers, 32 asphalt plant operators and 19 asphalt engineers. Smokers had lower concentrations of Clara cell protein (CC-16) and surfactant protein A, but higher concentrations of surfactant protein D, interleukin 6, C-reactive protein, fibrinogen and intercellular adhesion molecule (ICAM)-1 than non-smokers. Smokers reporting wheezing had lower mean CC-16 concentration than smokers not reporting wheezing (5.7 vs 8.6 microg l(-1); p = 0.05). Cholesterol, P-selectin and ICAM-1 were lower in pavers and operators at the end compared with the start of the season. This may be related to increased physical activity during the season.

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.

Lung surfactant alterations in pulmonary thromboembolism

Beside neonatal respiratory distress syndrome, secondary surfactant deficiency may occur in patients with mature lungs. Recent studies revealed quantitative and qualitative changes of lung surfactant in pulmonary thromboembolism (PTE) concerning the total phospholipids content in BAL fluid, alterations in surfactant phospholipids classes and a large-to-small aggregates ratio. Reduced expression of surfactant protein A (SP-A) mRNA and SP-A in lung tissue after pulmonary embolism was found. Serum levels of SP-A were significantly higher in patients with PTE than in other lung diseases, except COPD. Surfactant changes in PTE may result from damage of type II cells by hypoxia, leakage of plasma proteins into the airspaces and/or by reactive oxygen species. They can contribute to lung atelectasis and edema, and a further reduction in oxygen saturation as seen in clinical picture of PTE. Surfactant changes are reliable marker of lung injury that might become a prognostic indicator in patients with pulmonary thromboembolism.

Causal relationship between indium compound inhalation and effects on the lungs

BACKGROUND

Recent case reports and epidemiological studies suggest that inhalation of indium dust induces lung damage.

OBJECTIVES

To elucidate the dose-dependent effects of indium on the lungs and to prove a causal relationship more clearly.

METHODS

A baseline observation was conducted on 465 workers currently exposed to indium, 127 workers formerly exposed to indium and 169 workers without indium exposure in 12 factories and 1 research laboratory from 2003 to 2006. Indium in serum (In-S) was determined as an exposure parameter, and its effects on the lungs were examined.

RESULTS

The means of In-S in the current, former and no exposure workers were 8.35, 9.63 and 0.56 ng/ml, respectively. The current and former exposure workers had significantly higher levels of KL-6, and showed significant dose-dependent increases in KL-6, SP-D, and SP-A. Current exposure workers with In-S of 3 ng/ml or above demonstrated a significant increase of KL-6 in both GM and prevalence exceeding the reference value. Approximately a quarter of the former exposure workers had interstitial changes as seen on chest HRCT. In-S of exposed workers who had been working before improvements of the working environment (Group Bef) and those who started working after improvements (Group Aft) were 12.29 and 0.81 ng/ml, respectively. Adjusted odds ratios indicated 87%, 71% and 44% reductions among Group Aft workers who exceeded the reference values of KL-6, SP-D and SP-A, respectively.

CONCLUSION

Dose-dependent lung effects due to indium exposure were shown, and a decrease of indium exposure reduced the lung effects. An In-S value of 3 ng/ml may be a cut-off value which could be used to prevent early effects on the lungs.

Altered surfactant protein-A expression in type II pneumocytes in COPD

BACKGROUND

Pulmonary surfactant protein A (SP-A) is a lectin, with multiple functions that contribute to innate host defense and the regulation of the inflammatory process in the lung. In normal conditions, SP-A seems to protect against the effects of smoking. However, studies in smokers with or without COPD are limited.

METHODS

Western blots on lung tissue specimens from 60 male subjects (32 patients with COPD, 18 smokers without COPD, and 10 control nonsmokers) for SP-A and the housekeeping protein actin were carried out. Additionally, the SP-A expression pattern was evaluated by immunohistochemistry in formalin-fixed, paraffin-embedded lung tissue sections from the same subjects.

RESULTS

Western blots revealed significantly higher SP-A levels in control nonsmokers (4.8 +/- 0.05) when compared with patients with COPD (0.6 +/- 0.7) and smokers without COPD (2.4 +/- 0.9), (P < .05). However, differences that were not statistically significant were observed in SP-A levels among the patients with COPD and the smokers without COPD (P = .12). The immunohistochemical examinations showed an increase in the overall number of type II pneumocytes per high-power field in patients with COPD, but a decreased ratio of SP-A positive type II pneumocytes to total type II pneumocytes, compared with smokers without COPD (P = .001). This ratio was also correlated with FEV(1) (percent predicted [% pred]), (r = 0.490, P = .001). The overall number of alveolar macrophages per high-power field was significantly higher in patients with COPD compared with smokers without COPD (P = .001). The ratio of SP-A positive alveolar macrophages was increased in patients with COPD when compared with smokers without COPD (P = .002), while this was correlated with airway obstruction (FEV(1), % pred) (r = 0.281, P = .04).

CONCLUSIONS

Our results indicate that altered SP-A expression could be another link to COPD pathogenesis and highlights the need for further studies on surfactant markers in COPD.

Oxidative stress induced lung cancer and COPD: opportunities for epigenetic therapy

Reactive oxygen species (ROS) form as a natural by-product of the normal metabolism of oxygen and play important roles within the cell. Under normal circumstances the cell is able to maintain an adequate homeostasis between the formation of ROS and its removal through particular enzymatic pathways or via antioxidants. If however, this balance is disturbed a situation called oxidative stress occurs. Critically, oxidative stress plays important roles in the pathogenesis of many diseases, including cancer. Epigenetics is a process where gene expression is regulated by heritable mechanisms that do not cause any direct changes to the DNA sequence itself, and disruption of epigenetic mechanisms has important implications in disease. Evidence is emerging that histone deacetylases (HDACs) play decisive roles in regulating important cellular oxidative stress pathways including those involved with sensing oxidative stress and those involved with regulating the cellular response to oxidative stress. In particular aberrant regulation of these pathways by HDACs may play critical roles in cancer progression. In this review we discuss the current evidence linking epigenetics and oxidative stress and cancer, using chronic obstructive pulmonary disease and non-small cell lung cancer to illustrate the importance of epigenetics on these pathways within these disease settings.

Markers of early disease and prognosis in COPD

COPD is a complex disease with multiple pathological components, which we unfortunately tend to ignore when spirometry is used as the only method to evaluate the disorder. Additional measures are needed to allow a more complete and clinically relevant assessment of COPD. The earliest potential risk factors of disease in COPD are variations in the genetic background. Genetic variations are present from conception and can determine lifelong changes in enzyme activities and protein concentrations. In contrast, measurements in blood, sputum, exhaled breath, broncho-alveolar lavage, and lung biopsies may vary substantially over time. This review explores potential markers of early disease and prognosis in COPD by examining genetic markers in the α₁-antitrypsin, cystic fibrosis transmembrane conductance regulator (CFTR), and MBL-2 genes, and by examining the biochemical markers fibrinogen and C-reactive protein (CRP), which correlate with degree of pulmonary inflammation during stable conditions of COPD. Chronic lung inflammation appears to contribute to the pathogenesis of COPD, and markers of this process have promising predictive value in COPD. To implement markers for COPD in clinical practice, besides those already established for the α₁-antitrypsin gene, further research and validation studies are needed.