Blood Eosinophils and Exhaled Nitric Oxide: Surrogate Biomarkers of Airway Eosinophilia in Stable COPD and Exacerbation

In recent years, tremendous efforts have been devoted to characterizing the inflammatory processes in chronic obstructive pulmonary disease (COPD) in order to provide more personalized treatment for COPD patients. While it has proved difficult to identify COPD-specific inflammatory pathways, the distinction between eosinophilic and non-eosinophilic airway inflammation has gained clinical relevance. Evidence has shown that sputum eosinophil counts are increased in a subset of COPD patients and that these patients are more responsive to oral or inhaled corticosteroid therapy. Due to feasibility issues associated with sputum cell profiling in daily clinical practice, peripheral blood eosinophil counts and fractional exhaled nitric oxide levels have been evaluated as surrogate biomarkers for assessing the extent of airway eosinophilia in COPD patients, both in stable disease and acute exacerbations. The diagnostic value of these markers is not equivalent and depends heavily on the patient’s condition at the time of sample collection. Additionally, the sensitivity and specificity of these tests may be influenced by the patient’s maintenance treatment. Overall, eosinophilic COPD may represent a distinct disease phenotype that needs to be further investigated in terms of prognosis and treatment outcomes.

Sputum Cytokine Profiling in COPD: Comparison Between Stable Disease and Exacerbation

Purpose

Cytokines are extracellular signaling proteins that have been widely implicated in the pathogenesis of chronic obstructive pulmonary disease (COPD). Here, we investigated cytokine expression both at the mRNA and protein level in the sputum of healthy individuals, stable COPD patients, and those experiencing a severe acute exacerbation (AECOPD) requiring hospitalization.

Patients and Methods

Sputum was collected in 19 healthy controls, 25 clinically stable COPD patients, and 31 patients with AECOPD. In AECOPD patients sample collection was performed both at the time of hospital admission and at discharge following treatment. Sputum supernatant was analyzed by an antibody microarray detecting 120 cytokines simultaneously, while the mRNA expression of 14 selected cytokines in sputum cells was investigated by real-time PCR (qPCR).

Results

Proteomic analysis identified interleukin (IL)-6 and growth-regulated oncogene (GRO)α as the only sputum cytokines that were differentially expressed between stable COPD patients and healthy controls. At the onset of AECOPD, several cytokines exhibited altered sputum expression compared to stable COPD. Recovery from AECOPD induced significant changes in the sputum cytokine protein profile; however, the length of hospitalization was insufficient for most cytokines to return to stable levels. With regard to gene expression analysis by qPCR, we found that bone morphogenetic protein (BMP)-4 was up-regulated, while IL-1α, monokine-induced by interferon-γ (MIG), and BMP-6 were down-regulated at the mRNA level in patients with AECOPD compared to stable disease.

Conclusion

The sputum cytokine signature of AECOPD differs from that of stable COPD. Protein level changes are asynchronous with changes in gene expression at the mRNA level in AECOPD. The observation that the levels of most cytokines do not stabilize with acute treatment of AECOPD suggests a prolonged effect of exacerbation on the status of COPD patients.

Predictive Value of Exhaled Nitric Oxide and Blood Eosinophil Count in the Assessment of Airway Eosinophilia in COPD

Purpose

Fractional exhaled nitric oxide (FENO50) level and peripheral blood eosinophil count may serve as indicators of airway eosinophilia. The aim of this study was to estimate the diagnostic value of these markers for detecting airway eosinophilia in patients with stable chronic obstructive pulmonary disease (COPD) and those experiencing an acute exacerbation (AECOPD).

Patients and Methods

FENO50 levels, sputum and blood eosinophil counts were assessed in 53 clinically stable ex-smoker COPD patients and 67 ex-smoker COPD patients experiencing a severe exacerbation. In AECOPD, clinical variables were measured at the time of hospital admission and discharge following treatment.

Results

In stable COPD, blood eosinophil count but not FENO50 level was found to be a good predictor of airway eosinophilia (area under the receiver operating characteristic curve [ROC AUC]: ≥0.82). The sensitivity and the specificity of the test ranged between 75% and 98%, the negative predictive value (NPV) was high (>90%). In AECOPD, FENO50 was predictive for airway eosinophilia (ROC AUC: >0.8) with high NPV (>88%), but with lower sensitivity and specificity (64-70%). In contrast, the predictive accuracy of blood eosinophil count for airway eosinophilia in AECOPD was modest (ROC AUC: 0.54-0.63). The combined use of the two markers provided only limited additional benefit. Correlation analyses supported ROC curve findings.

Conclusion

In stable COPD the peripheral blood eosinophil count, while in AECOPD the FENO50 level is a good surrogate marker of airway eosinophilia.

Elimination of bacterial DNA during RNA isolation from sputum: Bashing bead vortexing is preferable over prolonged DNase treatment

Sputum often contains large amounts of contaminating bacterial DNA that, if not eliminated during RNA isolation, may interfere with gene expression studies. During RNA isolation only repeated DNase treatment can effectively remove contaminating bacterial DNA from samples, but this compromises RNA quality. In this study we tested alternative methods to facilitate the removal of DNA and improve the quality of RNA obtained. Sputum samples obtained from patients with chronic obstructive pulmonary disease were processed with dithiothreitol and subjected to various RNA isolation methods, yet with modified protocols. Modifications included prolonged DNase treatment or vortexing of sputum cells in the presence of beads prior to RNA isolation. Bacterial DNA contamination was tested by PCR using universal bacterial primers, while RNA quality was assessed by real-time PCR using GAPDH primers for amplicons of different length. We found that the RNeasy Plus Mini kit equipped with the gDNA eliminator spin column was able to completely eliminate bacterial DNA, if sputum cells were lysed in the presence of bashing beads. Notably, compared with the standard protocol, the modified procedure yielded better quality RNA as well, as indicated by improved threshold profiles of qPCR. Bead vortexing of cells was less effective when combined with other RNA isolation methods, and the repeated DNase treatment needed to completely remove contaminating DNA from the samples reduced the quality of RNA markedly. Bead vortexing in combination with certain RNA extraction methods greatly facilitates the isolation of sputum RNA that is free of contaminating bacterial DNA, and is suitable for downstream applications.

Monitoring Antioxidant Enzyme Activity during Exacerbations of Chronic Obstructive Pulmonary Disease

Superoxide dismutases (SODs) and catalase (CAT) have been implicated as major antioxidant enzymes of the human lungs. In this study, we investigated whether activities of these enzymes are altered in the airways of patients hospitalized with acute exacerbation of chronic obstructive pulmonary disease (AECOPD). SOD and CAT activities were measured in the sputum, exhaled breath condensate, and serum of 36 COPD patients experiencing a severe exacerbation. Measurements were performed using colorimetric assays in samples collected at the time of hospital admission and at the time of hospital discharge following treatment of AECOPD. For comparison, antioxidants were also assessed in 24 stable COPD patients and 23 healthy control subjects. SOD and CAT activities in sputum were significantly increased in patients with AECOPD compared to those with stable disease (SOD: 0.142 [0.053-0.81] vs. 0.038 [0.002-0.146] U/mL, p < 0.01; CAT: 48.7 [18.7-72.6] vs. 10.2 [2.9-40.6] nmol/min/mL, p < 0.05), while treatment of exacerbation led to a decrease in enzyme activities (SOD: 0.094 [0.046-0.45] U/mL, p < 0.05; CAT: 28.0 [7.3-60.4] nmol/min/mL, p < 0.005). No changes were observed in the serum (p > 0.05). Both SOD and CAT activities significantly correlated with sputum neutrophil and lymphocyte cell counts in patients with AECOPD. Moreover, SOD and CAT values correlated with each other and also with sputum malondialdehyde, an established marker for oxidative stress. Our data demonstrate that sputum antioxidant activity is elevated during COPD exacerbation and suggest that activation of SODs and CAT is an integral part of the human defense mechanism against the increased oxidant production associated with AECOPD.

Assessment of the circulating klotho protein in lung cancer patients

The anti-aging factor, klotho has been identified as a tumor suppressor in various human cancers, including lung cancer. In vitro studies provided evidence that klotho expression influences the characteristics of lung cancer cells, however, in vivo results are lacking. The aim of our study was to evaluate whether circulating klotho protein might serve as a potential biomarker of lung cancer. Blood samples were taken from 45 newly diagnosed lung cancer patients (31 NSCLC, 14 SCLC) and 43 control subjects. Plasma klotho concentration was measured using ELISA. No difference in plasma klotho values was detected between patients and control subjects (366.3 (257.9-486.8) vs. 383.5 (304.6-489.7) pg/ml respectively (median (IQR)); p > 0.05). Plasma klotho levels in patients with distant metastasis did not differ from less advanced stage disease (354.2 (306.9-433.3 vs. 328.5 (242.5-419.7) pg/ml, p > 0.05). In contrast, analyzed with one-way ANOVA, significant difference (p = 0.04) was found between the examined histological types of lung cancer: adenocarcinoma (353 (329.4-438.5) pg/ml), squamous cell carcinoma (308 (209.6-348.1) pg/ml) and small cell lung cancer (388.8 (289.9-495.4) pg/ml). However, Tukey's post hoc test did not reveal significant difference between any pairs of histological groups. There was no difference between any histological subtype and health either. Our results suggest that circulating klotho protein cannot be considered as a biomarker for lung cancer. Further studies are warranted in order to examine the relationship between klotho expression in lung tissue and circulating levels of the protein, and to explore its mechanism of action in lung cancer.

Analysis of Cytokine Pattern in Exhaled Breath Condensate of Patients with Squamous Cell Lung Carcinoma

Exhaled breath condensate (EBC) analysis is a promising method for investigating airway pathology. In this study we compared the cytokine pattern of EBC of patients suffering from squamous cell lung carcinoma with that of healthy smokers. Breath condensates collected from 8 smoking lung cancer patients before receiving any anticancer treatment and 8 smokers without any clinical or radiological evidence of pulmonary tumors were used for antibody microarray analysis testing 120 cytokines simultaneously. Ninety-eight cytokines on the array gave a detectable signal in both groups. Cytokine levels were similar across the samples, and none of the cytokines exhibited a significant increase or decrease in cancer patients as compared to healthy subjects with similar smoking status, lung function, and airway inflammation. The results of this pilot study suggest that patients with squamous cell lung carcinoma cannot be distinguished from smokers with no pulmonary tumors based on EBC cytokine signals only.

A European Respiratory Society technical standard: exhaled biomarkers in lung disease

Breath tests cover the fraction of nitric oxide in expired gas (F_eNO), volatile organic compounds (VOCs), variables in exhaled breath condensate (EBC) and other measurements. For EBC and for F_eNO, official recommendations for standardised procedures are more than 10 years old and there is none for exhaled VOCs and particles. The aim of this document is to provide technical standards and recommendations for sample collection and analytic approaches and to highlight future research priorities in the field. For EBC and F_eNO, new developments and advances in technology have been evaluated in the current document. This report is not intended to provide clinical guidance on disease diagnosis and management.Clinicians and researchers with expertise in exhaled biomarkers were invited to participate. Published studies regarding methodology of breath tests were selected, discussed and evaluated in a consensus-based manner by the Task Force members.Recommendations for standardisation of sampling, analysing and reporting of data and suggestions for research to cover gaps in the evidence have been created and summarised.Application of breath biomarker measurement in a standardised manner will provide comparable results, thereby facilitating the potential use of these biomarkers in clinical practice.

Kinetics of Exhaled Carbon Monoxide After Water-pipe Smoking Indoors and Outdoors

BACKGROUND

Despite accumulating evidence about its adverse health effects, water-pipe tobacco smoking has become very popular among youth. The aim of this study was to compare smoke exposure and the kinetics of exhaled carbon monoxide (eCO) between water-pipe and cigarette smokers under different conditions.

METHODS

Using a cross-over study design, changes in eCO and urinary cotinine levels were measured in a cohort of 32 healthy university students after sessions of water-pipe smoking indoors and outdoors. An indoor cigarette smoking session with equal amounts of tobacco was conducted for reference purposes. Both active and passive smokers participated in all sessions.

RESULTS

In indoor sessions, we found that among active participants, eCO levels were approximately 7.5-fold higher in water-pipe users than cigarette smokers. eCO levels remained significantly elevated even 10 h after discontinuing water-pipe smoking. Notably, eCO levels in passive water-pipe smokers were in the same range as in active cigarette smokers. Compared with indoor sessions, eCO levels in active water-pipe users were reduced in outdoor environments. Nonetheless, levels were still higher in these subjects than those in active cigarette smokers measured in indoor sessions. Urinary cotinine levels were comparable in active water-pipe and cigarette smokers.

CONCLUSIONS

Our results suggest that water-pipe smoking is associated with significantly higher toxicant exposure than cigarette smoking even in outdoor environments. Furthermore, even passive, indoor water-pipe smoke exposure may have significant health hazards compared with those of active cigarette smoking.

Oxidative stress in COPD: molecular background and clinical monitoring

Chronic obstructive pulmonary disease (COPD) is a major and rapidly increasing health problem associated with a chronic inflammatory response, predominantly in small airways and lung parenchyma. Oxidative stress induced by reactive oxygen and nitrogen species (ROS and RNS) plays a central role in the pathophysiology of COPD. There is evidence that several molecules formed during oxidative processes may have the potential to serve as biomarkers of oxidative stress in the airways of patients with COPD. Among these molecules carbon monoxide, ethane and pentane can be measured in the exhaled air, while 8-isoprostane, malondialdehyde, 4- hydroxyhexenal, 4-hyroxynonenal, acrolein, hydrogen peroxide, nitrogen oxides and 3-nitrotyrosine can be detected in exhaled breath condensate and/or sputum supernatant. In this review the molecular background of these processes including the formation of ROS and RNS, the biosynthesis of essential ω-3 and ω-6 polyunsaturated fatty acids as building blocks of lipids in the cellular membranes and their enzymatic and non-enzymatic metabolism to eicosanoids and related compounds have been summarized. Moreover, the formation of oxidative stress markers studied most commonly in the context of COPD has been briefly discussed. The associations between biomarkers and clinical variables have also been highlighted in an attempt to illustrate the potential clinical applicability of these biomarker measurements.

Sputum eicosanoid profiling in exacerbations of chronic obstructive pulmonary disease

BACKGROUND

Eicosanoids are small lipid molecules with diverse biological functions in the airways.

OBJECTIVES

The aim of this study was to investigate changes in leukotriene B4 (LTB4), 8-isoprostane, prostaglandin E2 (PGE2) and cysteinyl-leukotriene (cys-LT) levels in the sputum of patients with chronic obstructive pulmonary disease (COPD) at the onset of a severe exacerbation and during the course of recovery.

METHODS

Thirty-seven ex-smoker COPD patients suffering an episode of acute exacerbation were enrolled. Samples were taken (i) on hospital admission and (ii) after regular treatment. Twenty-five stable ex-smoker COPD patients served as controls. Eicosanoids were determined by enzyme immunoassay.

RESULTS

Sputum PGE2 [39.8 (13.3-103.3) vs. 5.05 (2.3-12.1) pg/ml, p < 0.001], 8-isoprostane [89.5 (36.9-184.7) vs. 29.7 (13.8-68.8) pg/ml, p < 0.01] and LTB4 [587.7 (252.9-774.8) vs. 276.1 (105.4-594.7) pg/ml, p < 0.05] levels were increased in patients with exacerbation compared to stable subjects. After treatment only PGE2 levels decreased significantly [at discharge: 19.6 (4.6-52.5) pg/ml, p < 0.01], the levels of other eicosanoids remained elevated (p = NS). Sputum cys-LT levels were similar in stable patients and in those with exacerbation and treatment did not influence cys-LTs either. There was a significant correlation between PGE2 and sputum neutrophil and lymphocyte cell counts in patients with exacerbation.

CONCLUSIONS

Our results suggest that 8-isoprostane, LTB4 and PGE2 but not cys-LTs may be involved in exacerbation-associated inflammatory processes in the airways of patients with COPD. Validation of PGE2 for use as a biomarker of recovery from an exacerbation requires further studies.

Exhaled breath condensate pH decreases during exercise-induced bronchoconstriction

BACKGROUND AND OBJECTIVE

Exercise-induced bronchoconstriction (EIB) is the temporary narrowing of the airways caused by physical exercise. Its exact pathophysiology is unclear; however, acute changes in airways pH may play a role. Exhaled breath condensate (EBC) pH was suggested as a surrogate indicator for airway acid-base status, but its value is also affected by volatile molecules and respiratory droplet dilution. The aim of the study was to assess changes in EBC pH during EIB.

METHODS

Twenty-two asthmatics who reported breathlessness following exercise and 16 healthy individuals participated in the study. Lung function test was performed and exhaled breath samples were collected for pH, dilution factor and volatile compound pattern measurements (Cyranose 320) pre-exercise and at 0, 10, 20 and 30 min after physical exercise challenge. Fractional exhaled nitric oxide was measured before exercise.

RESULTS

EIB developed in 13 asthmatic subjects. In these participants, but not in the EIB-negative asthmatics (P = 0.51), EBC pH reduced significantly during exercise (P = 0.01). In addition, changes in EBC pH were related to the degree of bronchospasm in the EIB-positive group (P = 0.01, r = 0.68). Exhaled volatile pattern became altered (P < 0.05) during exercise in all subjects (asthmatics and controls). EBC pH changes were not related to EBC dilution or volatile compound pattern alterations (P > 0.05).

CONCLUSIONS

The development of EIB was related to acute changes of EBC pH, which suggest the role of airway pH decrease in the pathophysiology of EIB. Exercise-induced changes in exhaled biomarkers suggest methodological precautions to avoid physical exercise before performing exhaled breath tests.

Exhaled breath condensate pH in patients with cystic fibrosis

OBJECTIVE AND DESIGN

Exhaled breath condensate (EBC) pH has been proposed as a useful, non-invasive marker of airway inflammation in pulmonary diseases. In this study we tested whether cystic fibrosis (CF) is associated with acidification of EBC, when pH is assessed by the CO(2) gas standardization method.

METHODS

EBC was collected using two different devices (EcoScreen and R-Tube) in 46 stable CF patients during routine clinical visits and in 28 healthy controls.

RESULTS

Mean EBC pH in CF patients and in healthy controls was similar (EcoScreen: CF patients: 6.38 ± 0.03 versus controls: 6.39 ± 0.03, p = 0.699; R-tube: CF patients: 5.94 ± 0.04 versus controls: 6.02 ± 0.03, p = 0.159). Inflammatory cell counts in spontaneously expectorated sputum obtained in a subset of patients (n = 20) showed no correlation with pH values. EBC samples collected with the R-tube were more acidic than those collected with the EcoScreen device (p < 0.001).

CONCLUSIONS

Our data suggest that EBC pH does not discriminate between healthy controls and those with CF disease indicating that the clinical applicability of EBC pH measurements for assessing airway inflammation in CF is limited.

Assessment of reproducibility of exhaled hydrogen peroxide concentration and the effect of breathing pattern in healthy subjects

BACKGROUND

Hydrogen peroxide (H2O2) is detectable in exhaled breath condensate (EBC) and has been proposed to be a surrogate marker of oxidative stress in the airways. In this study we tested whether the breathing pattern during EBC collection influences the concentration of exhaled H2O2.

METHODS

EBC was collected during (1) tidal breathing and (2) breathing with increased tidal volume for 10 min from 16 healthy volunteers. On-line H2O2 measurement was performed by the EcoCheck™ biosensor system. Repeated measurements were also conducted to assess intrasubject reproducibility.

RESULTS

Minute ventilation, tidal volume, expiratory flow rate were all increased significantly when subjects were asked to perform breathing with increased tidal volume. In parallel, EBC volume increased (1413±59 vs. 1959±71 μL, p<0.001), whereas exhaled H2O2 levels decreased significantly (1400±170 vs. 840±130 nmol/L, p<0.001). H2O2 levels did not correlate with any individual breathing parameters (p>0.05). Assessment of intersubject variability of H2O2 measurements during the two types of breathing revealed a coefficient of variation of 49 and 54%, respectively. The EBC H2O2 measurement was highly reproducible (888±176 vs. 874±156 nmol/L) as tested during normal breathing.

CONCLUSIONS

These data demonstrate that the concentration of H2O2 in EBC depends on the ventilatory pattern during sample collection that has to be taken into consideration in all EBC H2O2 assays.

Low-molecular-weight heparins do not modify obliterative airway disease in rat tracheal allografts

Immunosuppressive and antiproliferative effects of heparin may be beneficial in the field of solid organ transplantation. The aim of this study was to examine the effect of low-molecular-weight heparin (LMWH) compounds on the development of obliterative airway disease (OAD) in the rat tracheal transplant model. Allogenic heterotopic tracheal transplantations were performed from Brown-Norway into Lewis rats. Recipients were treated either with nadroparin, enoxaparin, parnaparin, or vehicle from day 0 until harvesting at day 7 or 21. Graft rejection was morphometrically assessed to determine the extent of luminal obliteration end epithelial necrosis. All tracheal grafts harvested at day 7 demonstrated nearly equivalent degree of luminal obstruction regardless of treatment regimen. Likewise, at day 21 the extent of airway narrowing and the degree of inflammatory cell infiltration were similar among the groups. Moreover, loss of airway epithelium was not prevented by LMWH treatments. Finally, intragraft mRNA expression for transforming growth factor-β1 and platelet-derived growth factor-A, interleukin-2, interferon-γ, and monocyte chemoattractant protein-1 did not differ between the groups. In contrast with findings in other animal models, treatment with LMWH preparations did not modify the development of OAD in rat tracheal allografts.

Assessment of exhaled breath condensate pH in exacerbations of asthma and chronic obstructive pulmonary disease: A longitudinal study

RATIONALE

Exhaled breath condensate pH has been proposed as a noninvasive marker of airway inflammation. However, due to standardization difficulties in pH measurement techniques, different pH readings were obtained in previous studies.

OBJECTIVES

In this longitudinal study we assessed condensate pH in patients with an exacerbation of asthma or chronic obstructive airway disease using the very precise carbon dioxide standardization method that negates the effect of this gas on condensate acidity.

METHODS

Condensate pH, fractional exhaled nitric oxide, lung function, and blood gases were measured in 20 nonsmoking patients with asthma and 21 smoking and 17 ex-smoking patients with chronic obstructive airway disease first at hospital admission due to an acute exacerbation of the disease and again at discharge after treatment. Condensate pH was also assessed in 18 smoking and 18 nonsmoking healthy control subjects.

MEASUREMENTS AND MAIN RESULTS

In patients with asthma, condensate pH was significantly decreased at the time of exacerbation compared with nonsmoking control subjects and increased with treatment. In patients with chronic obstructive airway disease, condensate pH remained unchanged during exacerbation, both in smokers and ex-smokers. Nevertheless, condensates collected from smokers were more acidic than those of ex-smokers. A similar difference was observed between smoker and nonsmoker healthy control subjects. No correlations were found between condensate pH and fractional exhaled nitric oxide or lung function variables measured either at admission or discharge.

CONCLUSIONS

Our data suggest that exacerbation of asthma, but not chronic obstructive airway disease, is associated with acidification of breath condensate.

Assessment of exhaled nitric oxide by a new hand-held device

BACKGROUND

Fractional exhaled nitric oxide (FENO) has been implicated as a pulmonary biomarker. The aim of this study was to compare the performance of a new hand-held device to a standard chemiluminescence analyzer and to another portable device.

METHODS

FENO levels measured by NObreath (Bedfont) were compared to those of (1) a chemiluminescence detector (Logan, Logan Research) and (2) the electrochemical portable NIOX MINO (Aerocrine) in 18 healthy volunteers on three consecutive occasions: in the morning, 1 h and 24 h later.

RESULTS

Comparing FENO levels obtained by NObreath to those by Logan values were similar and a very close linear relationship was found between the two devices (r = 0.923, p < 0.001). The mean inter-device difference in FENO level was -3.45 ppb and the limits of agreement (Bland-Altman test) were -10.98 and 4.08 ppb. In the second series FENO levels obtained by NObreath were found to be slightly higher compared to those of NIOX MINO, but still showed a close correlation (r = 0.681, p < 0.001). The mean inter-device difference in FENO level was 4.36 ppb and the limits of agreement were -7.38 and 16.1 ppb. Analyzing the repeated FENO measurements, the mean coefficient of variation using NObreath tended to be lower than that of NIOX MINO (16.9 vs. 24.7%, p = 0.059), while it was similar as the value obtained with Logan (11.8 vs. 9.0%, p = 0.342).

CONCLUSIONS

FENO values measured with NObreath are reproducible and in good agreement with those obtained by NIOX MINO and Logan indicating that NObreath is suitable for use in clinical practice.

Relationship between exhaled nitric oxide and treatment response in COPD patients with exacerbations

BACKGROUND AND OBJECTIVE

Fractional exhaled nitric oxide (FENO) has been implicated as a pulmonary biomarker in various respiratory diseases, including COPD. In this longitudinal study, the benefit of measuring FENO in a routine clinical setting was assessed in COPD patients hospitalized with an exacerbation of the disease.

METHODS

FENO, lung function and blood gases were measured in 58 COPD patients at hospital admission due to an exacerbation, and at discharge following treatment with corticosteroids and bronchodilators.

RESULTS

FENO levels were significantly decreased at discharge, compared with those at admission (geometric mean 25.3 ppb (95% CI: 21.2-30.1) vs 19.7 ppb (95% CI: 17.2-22.6); P = 0.002). There was a significant positive correlation between FENO concentrations at admission and the increase in FEV(1) after treatment (r = 0.441, P < 0.001), and a significant inverse correlation between FENO values at admission and the mean length of hospital stay (r = -0.297, P = 0.016). Using receiver operating characteristic curve analysis, the optimum cut point for FENO as a predictor for significant increase in FEV(1) was 26.8 ppb (sensitivity: 74%, specificity: 75%). There were no correlations between FENO levels and absolute values for lung function variables at admission or discharge.

CONCLUSIONS

These data suggest that FENO levels determined at hospital admission may predict the overall response to treatment in COPD patients with acute exacerbations.

Analysis of cytokine pattern in exhaled breath condensate of patients with squamous cell lung carcinoma

Exhaled breath condensate (EBC) analysis is a promising method for investigating airway pathology. In this study we compared the cytokine pattern of EBC of patients suffering from squamous cell lung carcinoma with that of healthy smokers. Breath condensates collected from 8 smoking lung cancer patients before receiving any anticancer treatment and 8 smokers without any clinical or radiological evidence of pulmonary tumors were used for antibody microarray analysis testing 120 cytokines simultaneously. Ninety-eight cytokines on the array gave a detectable signal in both groups. Cytokine levels were similar across the samples, and none of the cytokines exhibited a significant increase or decrease in cancer patients as compared to healthy subjects with similar smoking status, lung function, and airway inflammation. The results of this pilot study suggest that patients with squamous cell lung carcinoma cannot be distinguished from smokers with no pulmonary tumors based on EBC cytokine signals only.

Adenosine triphosphate in exhaled breath condensate of healthy subjects and patients with chronic obstructive pulmonary disease

OBJECTIVES

The effect of hypoxic relapse of chronic obstructive pulmonary disease (COPD) on lung adenosine triphosphate (ATP) concentration was studied measuring ATP in exhaled breath condensate (EBC).

SUBJECTS

Thirty COPD patients with severe exacerbation, thirteen healthy non-smokers and thirteen healthy smokers.

METHODS

ATP was detected using a luciferin-luciferase assay, dilution of airway droplets in EBC was assessed measuring sample conductivity.

RESULTS

ATP concentrations were similar in COPD patients, non-smoking and smoking healthy individuals (141 +/- 44, 115 +/- 21 and 90 +/- 15 pM; p = 0.66). After treatment oxygenation of COPD patients improved (6.85 +/- 1.29 kPa vs. 8.20 +/- 1.28 kPa, p < 0.001), but EBC ATP concentration was similar to that of admission (p = 0.84). There was no correlation between EBC ATP concentration and airway droplet dilution.

CONCLUSION

ATP detected in EBC indicates the presence of ATP in airway lining fluid. Lack of difference in ATP concentration between health and COPD suggests that airway ATP level is under complex control of multiple factors.

Late treatment with angiotensin-converting enzyme inhibitors plus endothelin receptor antagonists ameliorates rat tracheal allograft rejection

Inhibition of the renin-angiotensin and endothelin (ET) systems prevents the development of obliterative airway disease (OAD) in rat tracheal allografts. In this study, we assessed whether these therapeutic approaches are effective even when the same were started after signs of OAD were already manifest. Rat tracheas were heterotopically transplanted from Brown-Norway donors into Brown-Norway or Lewis recipients. Allograft recipients received bosentan, ramipril, bosentan plus ramipril or vehicle from day 10 to 24. Untreated allografts and isografts were harvested at day 10 or 24. In tracheal grafts, morphometric studies together with molecular analysis by real-time PCR were performed. Fibroproliferative process in untreated tracheal allografts but not in isografts started already at day 10. Neither bosentan nor ramipril treatment alone as monotherapy could modify the development of OAD when administered only between day 10 and day 24. By contrast, the combination treatment of bosentan and ramipril ameliorated airway obstruction by day 24, which was accompanied by reduced mRNA expression of intragraft transforming growth factor-beta1 and platelet-derived growth factor-A and -B chains. Only the combined blockade with angiotensin-converting enzyme inhibitors and ET receptor antagonists can reduce the progression of OAD in this model if the treatment is initiated late in the disease course.

Variability of exhaled breath condensate pH in lung transplant recipients

BACKGROUND

Measurement of pH in exhaled breath condensate (EBC) may represent a novel method for investigating airway pathology.

OBJECTIVES

The aim of this longitudinal study was to assess the variability of EBC pH in stable lung transplant recipients (LTR).

METHODS

During routine clinical visits 74 EBC pH measurements were performed in 17 LTR. EBC pH was also measured in 19 healthy volunteers on four separate occasions. EBC pH was determined at standard CO2 partial pressure by a blood gas analyzer.

RESULTS

Mean EBC pH in clinically stable LTR and in controls was similar (6.38 +/- 0.09 vs. 6.44 +/- 0.16; p = nonsignificant). Coefficient of variation for pH in LTR and controls was 2.1 and 2.3%, respectively. The limits of agreement for between-visit variability determined by the Bland-Altman test in LTR and healthy volunteers were also comparable (-0.29 and 0.46 vs. -0.53 and 0.44).

CONCLUSIONS

Our data suggest that the variability of EBC pH in stable LTR is relatively small, and it is similar to that in healthy nontransplant subjects.

Angiotensin type 1 and type 2 receptor blockade in chronic allograft nephropathy

Angiotensin-II (Ang-II) type 1 (AT(1)) receptor blockers may delay the progression of chronic allograft nephropathy (CAN). However, neither the optimal time for initiating AT(1) receptor blockade in order to delay CAN potentially nor the role of Ang-II type 2 (AT(2)) receptors under AT(1) receptor blockade is known. Both AT receptors can regulate p53 expression and apoptosis. We investigated what time of initiation with AT(1) blockers most effectively delayed CAN as well as the role of the AT(2) receptor, and how angiotensin receptor blockade affected apoptosis and its regulating factors in this context in a rat model. Kidneys of Fisher (F344) rats were transplanted into Lewis rats. Animals were treated with AT(1) (candesartan) and/or AT(2) (PD123319) receptor antagonists, a calcium channel blocker, or vehicle (treatment periods: day -7 before to week 24 after transplantation (long term), week 12 to week 24 (late), day -7 to day +5 (early)) and observed the animals for 24 weeks. Reduction of proteinuria, grade of CAN, and number of apoptotic cells was most pronounced in animals receiving long-term AT(1) receptor blockade. A combined AT(1)/AT(2) blocker treatment reduced CAN similarly to AT(1) blocker treatment alone. The number of apoptotic cells and the level of p53 mRNA were significantly lower in long-term AT(1) blocker-treated animals. In summary, AT(1) receptor blockade delayed the progression of CAN, particularly in animals treated long term. Reduction of apoptosis could be related to these beneficial effects. The AT(2) receptor does not appear to play an important role in CAN.

Pulmonary infections increase exhaled nitric oxide in lung transplant recipients: a longitudinal study

The aim of this longitudinal study was to test whether pulmonary infections influence fractional exhaled nitric oxide levels (FENO) in otherwise clinically-stable lung transplant recipients. Levels of FENO were measured at least on 11 occasions in nine lung transplant recipients who attended for routine or urgent clinical review over 27.0 +/- 3.2 months period. Diagnosis of infection was based on clinical symptoms, functional measurements and radiological findings. Concentrations of FENO were also determined in 12 healthy volunteers. During follow-up, six patients had one, two had three, and one had four episodes of pulmonary infections. Overall, six upper and 10 lower respiratory tract infections were noted. Recipients with active infections developed increased FENO levels as compared with their own baseline levels measured in the clinically well period (10.8 +/- 1.3 vs. 7.6 +/- 1.1 ppb, p < 0.05). After antibiotic treatment, elevated FENO concentrations returned to baseline in association with full clinical recovery. Baseline FENO levels in lung transplant recipients and in healthy volunteers (6.0 +/- 0.5 ppb) were similar. The sensitivity and specificity of FENO measurement in detecting pulmonary infections were 57 and 96%, respectively. Our data suggest that pulmonary infections are associated with increased FENO levels in patients with lung allografts. Nevertheless, the measurement of FENO by itself as a screening tool for infections seems to be limited by its low sensitivity.

Inhibition of Matrix Metalloproteinases During Chronic Allograft Nephropathy in Rats

BACKGROUND

Chronic allograft nephropathy (CAN) belongs to the major causes of long-term kidney allograft failure. One of the histologic hallmarks of CAN is interstitial fibrosis, influenced by matrix metalloproteinases (MMPs) that are controlling extracellular matrix (ECM) degradation. Whether MMPs affect the development and progression of CAN is not clear so far. To analyze the role of MMPs in CAN, we investigated the effects of an early and a late application of BAY 12-9566, an inhibitor of MMP-2, -3, and -9 on the development and progression of CAN in a rat kidney-transplantation model.

METHODS

Fisher kidneys were orthotopically transplanted into Lewis recipients that were treated with BAY 12-9566 (15 mg/kg per day) or vehicle either for the first 10 days after transplantation (early treatment) or from week 12 to week 20 after transplantation (late treatment). Proteinuria was analyzed every 4 weeks up to week 20 after transplantation when kidney grafts were removed for further analysis.

RESULTS

Early MMP-inhibition resulted in a significantly reduced 24-hour protein excretion that was paralleled by a lower grade of CAN after 20 weeks. However, late MMP inhibition starting at week 12 after transplantation resulted in significantly higher proteinuria and a higher grade of CAN as compared with controls. Furthermore, transforming growth factor-beta and platelet-derived growth factor-B chain mRNA levels were significantly increased in these animals.

CONCLUSIONS

Inhibition of MMPs early after transplantation reduced the development and progression of CAN but promoted CAN if initiated at later stages. Thus, MMPs are involved in the development and progression of CAN.

Effects of progesterone and selective oestrogen receptor modulators on chronic allograft nephropathy in rats

BACKGROUND

We recently demonstrated that oestrogens ameliorate the progression of chronic allograft nephropathy (CAN). In our present study, we investigated the role of progesterone and selective oestrogen receptor modulators (SERMs) in this process.

METHODS

Female Fisher (F344) kidneys were orthotopically transplanted into intact or ovariectomized female Lewis recipients. Ovariectomized recipients were divided into four groups and were treated with either progesterone alone or in combination with oestradiol, oestradiol alone or vehicle. Intact recipients were divided into three groups and were treated with SERMs such as tamoxifen and one of its new derivatives, droloxifene or vehicle. Animals were harvested 24 weeks after transplantation for histological and immunohistological studies as well as for molecular analysis.

RESULTS

Administration of progesterone resulted in increased urinary protein excretion as well as profound glomerulosclerosis and mononuclear cell infiltration. The combined treatment had similar detrimental effects on the development of CAN. In contrast, oestradiol treatment alone improved graft function, reduced glomerulosclerosis and diminished cellular infiltration. SERMs again impaired allograft function and promoted the development of CAN. Renal allograft damage paralleled intragraft mRNA expression of transforming growth factor-beta1 in all groups.

CONCLUSIONS

Our results suggest that addition of progesterone diminishes the beneficial effects of oestrogens on the development of CAN in rats. Similarly to progesterone, SERMs worsened long-term renal allograft outcome.

Chronic renal failure leads to reduced flow-dependent dilation in isolated rat skeletal muscle arterioles due to lack of NO mediation

BACKGROUND

Chronic renal failure (CRF) is frequently accompanied by systemic vascular alterations which further increase the morbidity and mortality of these patients. However, the nature and the underlying mechanisms of vascular dysfunction are not completely understood. We hypothesized that--in addition to other factors--CRF alters local vasomotor mechanisms that are intrinsic to the vascular wall.

METHODS

Changes in the diameter of isolated, pressurized (at 80 mm Hg) gracilis skeletal muscle arterioles (diameter approximately 150 microm) of female Wistar rats were investigated by videomicroscopy. Arteriolar responses to an increase in flow and vasoactive agents in partially nephrectomized (NX) and sham-operated (control) rats were compared.

RESULTS

In NX rats, serum creatinine and urine protein excretion were increased. Compared to controls, increases in intraluminal flow (from 0 to 40 microl/min) resulted in significantly reduced dilation in arterioles of NX rats (maximum: 32 +/- 4 vs. 15 +/- 4 microm, p < 0.05). Inhibition of nitric oxide (NO) synthesis with L-NAME reduced the dilation of control arterioles but did not affect responses of NX arterioles. Also, dilations in response to histamine were significantly reduced in arterioles from NX rats as compared to control rats. L-NAME significantly decreased histamine-induced dilations of control arterioles, but it did not affect responses of NX arterioles. Dilations in response to the NO donor sodium nitroprusside were also significantly decreased in NX arterioles as compared to responses of control vessels, whereas responses to adenosine and norepinephrine were not significantly different in the two groups.

CONCLUSIONS

We conclude that in rat skeletal muscle arterioles, CRF induced by renal mass reduction alters the mechanosensitive and agonist-induced responses of peripheral arterioles, in part by interfering with NO-signaling mechanisms. These alterations could contribute to increased peripheral vascular resistance and further aggravate the cardiovascular complications in CRF.

Apoptosis and treatment of chronic allograft nephropathy with everolimus

BACKGROUND

Chronic allograft nephropathy (CAN) is responsible for most cases of late kidney allograft loss. However, no effective treatment is available so far. Everolimus (RAD) (40-O [2-hydroxyethyl] rapamycin) is a new immunosuppressive agent with antiproliferative and apoptosis-enhancing effects. We asked whether everolimus can ameliorate CAN even at advanced stages, whether everolimus treatment affects the level of growth factor mRNA, and whether everolimus treatment affects the number of apoptotic cells in the graft.

METHODS

We transplanted kidneys from Fisher rats into Lewis rats and treated recipients with everolimus over different time periods. Grafts were analyzed 20 or 28 weeks after transplantation.

RESULTS

Everolimus delayed the progression of CAN when started at an early stage. Surprisingly, everolimus even ameliorated CAN when initiated at an advanced stage. Interestingly, apoptosis was more prevalent in treated animals, particularly in those with delayed treatment as compared with controls.

CONCLUSIONS

Everolimus ameliorates CAN as a result of antiproliferative or apoptosis-enhancing effects.

Estradiol is nephroprotective in the rat remnant kidney

BACKGROUND

Female sex hormones may influence the progression of renal diseases. We therefore evaluated the effects of estradiol on the development of glomerulosclerosis in a remnant kidney model.

METHODS

Ovariectomized or intact female Wistar rats underwent 5/6 nephrectomy. Ovariectomized animals were treated with vehicle, 17beta-estradiol alone or in combination with progesterone, intact rats received vehicle only. Twenty-four weeks after renal ablation, histological as well as molecular analysis were performed.

RESULTS

Vehicle-treated ovariectomized animals developed severe proteinuria and glomerulosclerosis as compared with vehicle-treated intact rats. In addition, renal mRNA levels of platelet-derived growth factor-A chain (PDGF-A) were increased. Estradiol replacement reduced proteinuria, which was paralleled by a diminished glomerular injury and reduced transforming growth factor-beta1 (TGF-beta1) and PDGF-A mRNA expression. In animals that received combined hormone treatment there were no significant differences in proteinuria, creatinine clearance, renal histopathology and growth factor mRNA levels compared with those measured in vehicle-treated ovariectomized rats. Serum cholesterol and triglyceride levels were comparable between all groups during the whole follow-up period.

CONCLUSIONS

The data suggest that estrogens protect against the development of glomerulosclerosis in the rat remnant kidney model.

Opposite effects of testosterone and estrogens on chronic allograft nephropathy

In the present study we investigated whether donor gender or the effects of sex hormones play the greater role in the development of chronic allograft nephropathy. Kidneys of male and female Fisher rats were orthotopically transplanted into castrated male Lewis recipients. Animals were treated with testosterone, estradiol, or vehicle and the kidneys were harvested 20 weeks after transplantation for histological, immunohistological, and molecular analysis. Testosterone treatment resulted in increased proteinuria and profound glomerulosclerosis, irrespective of donor gender. In addition, mRNA levels of transforming growth factor-beta1 (TGF-beta1) and platelet-derived growth factor-A and B (PDGF-A and B) chains were enhanced in these allografts. Estradiol reduced glomerulosclerosis and mononuclear cell infiltration in allografts of both genders that paralleled a decreased mRNA expression of TGF-beta1, PDGF-A and B. No donor gender-related differences were noted in vehicle-treated animals. Our findings demonstrate that sex hormones rather than donor gender have a significant impact on chronic allograft nephropathy.

Early application of Met-RANTES ameliorates chronic allograft nephropathy

BACKGROUND

Initial insults to kidney allografts, characterized by infiltration of mononuclear inflammatory cells, contribute to chronic allograft nephropathy. Chemokines such as RANTES (regulated upon activation, normal T cell expressed) are thought to be responsible for the recruitment and activation of infiltrating cells. The present study investigated whether early application of Met-RANTES, a chemokine receptor antagonist that blocks the effects of RANTES, can protect renal allografts from long-term deterioration.

METHODS

Fisher (F344) rat kidneys were orthotopically transplanted into Lewis recipients and treated with cyclosporine A (1.5 mg/kg/day) for the first 10 days following transplantation, together with either Met-RANTES at 40 microg/day, 200 microg/day or vehicle for the first 7 days. Animals were harvested at 2 and 28 weeks after transplantation for histologic, immunohistologic and molecular analysis.

RESULTS

Met-RANTES treatment reduced the infiltration of lymphocytes and macrophages in allografts at 2 weeks after transplantation, accompanied by decreased mRNA expression of interleukin (IL)-2, IL-1beta, tumor necrosis factor-alpha (TNF-alpha) and RANTES. At post-transplantation week 28, Met-RANTES treatment at high and low doses reduced urinary protein excretion and significantly ameliorated glomerulosclerosis, interstitial fibrosis, tubular atrophy, intimal proliferation of graft arteries and mononuclear cell infiltration. However, creatinine clearance was not influenced by Met-RANTES. Furthermore, Met-RANTES suppressed the mRNA expression of transforming growth factor-beta (TGF-beta) and platelet-derived growth factor-B (PDGF-B).

CONCLUSIONS

Blockade of chemokine receptors by Met-RANTES diminishes early infiltration and activation of mononuclear cells in the grafts, and thus reduces the pace of chronic allograft nephropathy.

Contribution of androgens to chronic allograft nephropathy is mediated by dihydrotestosterone

BACKGROUND

Donor and recipient gender influence long-term allograft outcome after kidney transplantation. Sex hormones are likely to contribute to these gender-related differences. The present study investigated the role of androgens and their inhibition on the development of chronic allograft nephropathy.

METHODS

Male or female Fisher (F344) kidneys were orthotopically transplanted into intact male Lewis recipients. Animals were treated either with testosterone, the antiandrogen flutamide, the 5alpha-reductase inhibitor finasteride, or vehicle. Twenty weeks after transplantation animals were harvested for histology, immunohistology, and molecular analysis.

RESULTS

Testosterone treatment resulted in an increased proteinuria as well as profound glomerulosclerosis, tubulointerstitial fibrosis, and mononuclear cell infiltration that paralleled enhanced intragraft mRNA levels of transforming growth factor-beta (TGF-beta) and platelet-derived growth factor-A and -B chain (PDGF-A and -B). In contrast, flutamide and finasteride reduced glomerulosclerosis as well as the inflammatory cell infiltration associated with decreased TGF-beta, PDGF-A, and -B chain mRNA expression. No gender-related donor differences were noted between the groups.

CONCLUSIONS

Our data suggest that dihydrotestosterone mediates the adverse effects of androgens on chronic allograft nephropathy. The inhibition of androgens improves long-term allograft outcome after kidney transplantation.

Adenovirus-mediated Bcl-2 gene transfer inhibits apoptosis and promotes survival of allogeneic transplanted hepatocytes

BACKGROUND

Donor hepatocyte apoptosis that is induced by host cytotoxic T lymphocytes (CTLs) limits the application of hepatocyte transplantation. Hepatocytes from Bcl-2 transgenic mice can resist the lethal effect of anti-Fas antibody. However, the anti-apoptotic effect of Bcl-2 expression on allogeneic transplanted hepatocytes remains elusive. This study tested the feasibility of Bcl-2 gene transfer as an approach to inhibit CTL-mediated apoptosis in allogeneic transplanted hepatocytes.

METHODS

An adenovirus vector that encoded human Bcl-2 gene (AdCMVhBcl-2) was used to transfect cultured rat hepatocytes, which were then transplanted into allogeneic spleens. DNA fragmentation and caspase-3 activation were examined by terminal deoxynucleotidyl transferase-mediated deoxyuridine triphosphate nick end-labeling assay and immunohistochemistry for active caspase-3, respectively. Cocultivation of hepatocytes and allogeneic CD8(+) T lymphocytes was performed, and cytotoxicity on hepatocytes was examined by alanine transaminase release.

RESULTS

Bcl-2 gene transfer inhibited apoptosis and increased liver-associated enzyme activities in allogeneic transplanted hepatocytes, which were associated with inhibition of caspase-3 activation. Alanine transaminase release in hBcl-2 modified hepatocytes was lower compared with controls, which could not be further decreased by inhibition of Fas ligand and granzyme B.

CONCLUSIONS

Adenovirus-mediated Bcl-2 gene transfer blocks CTL-mediated apoptosis in allogeneic hepatocytes by inhibition of caspase-3 activation. Bcl-2 gene transfer could be used to promote survival of transplanted hepatocytes.

Recipient age and weight affect chronic renal allograft rejection in rats

Nephron doses and immune responses change with age. Therefore, age is a potential risk factor for graft survival after kidney transplantation. The aim of this study was to determine whether age-related differences are of importance for long-term outcomes after renal transplantation. Kidneys from Fisher 344 rats were orthotopically transplanted into nephrectomized Lewis rats. Kidneys were transplanted using donors and recipients of three age levels, i.e., young (8 wk of age), adult (16 wk of age), and old (40 wk of age). Rats were killed 24 wk after transplantation, and functional, morphologic, and molecular evaluations were performed. Recipient age, rather than donor age, determined graft survival rates. No significant correlation was observed between donor kidney weight on the day of transplantation and morphologic results. Advanced recipient age was associated with reduced creatinine clearance, more severe histologic injuries, including extended glomerular sclerosis, interstitial fibrosis, and vascular lesions, more pronounced cellular infiltration, and greater expression of transforming growth factor-beta and platelet-derived growth factor A and B chains. Although no significant correlation between donor age or kidney weight on the day of transplantation and morphologic results was observed, there was a significant correlation between recipient body weight on the day of transplantation and allograft injury. It is concluded that recipient age and weight affect chronic renal rejection. Renal allografts may benefit from young recipient age but may deteriorate in old recipients, suggesting effects of recipient functional demand on long-term outcomes.