Jan Stolk

Monocyte chemoattractant protein 1, interleukin 8, and chronic airways inflammation in COPD

Chronic obstructive pulmonary disease (COPD) is one of the most common causes of death, with cigarette smoking among the main risk factors. Hallmarks of COPD include chronic airflow obstruction and chronic inflammation in the airway walls or alveolar septa. An earlier study reported elevated numbers of macrophages and mast cells within the bronchiolar epithelium in smokers with COPD, compared with smokers without. Since specific chemokines may be involved in this influx, the in situ protein and mRNA expression of monocyte chemoattractant protein 1 (MCP‐1) and of interleukin 8 (IL‐8) were studied in tumour‐free peripheral lung tissue resected for lung cancer of current or ex‐smokers with COPD (FEV1<75%; n=14) and without COPD (FEV1>84; n=14). MCP‐1 was expressed by macrophages, T cells, and endothelial and epithelial cells. Its receptor, CCR2, is expressed by macrophages, mast cells, and epithelial cells. IL‐8 was found in neutrophils, epithelial cells, and macrophages. In subjects with COPD, semi‐quantitative analysis revealed 1.5‐fold higher levels of MCP‐1 mRNA and IL‐8 mRNA and protein in bronchiolar epithelium (p<0.01) and 1.4‐fold higher levels of CCR2 in macrophages (p=0.014) than in subjects without COPD. The bronchiolar epithelial MCP‐1 mRNA expression correlated with both CCR2 expression on macrophages and mast cells (p<0.05) and the numbers of intra‐epithelial macrophages and mast cells (p<0.04). The epithelial IL‐8 expression did not correlate with the numbers of neutrophils, macrophages, CD45RO+, CD8+, or mast cells. These data suggest that MCP‐1 and CCR2 are involved in the recruitment of macrophages and mast cells into the airway epithelium in COPD. Copyright

Hereditary alpha-1-antitrypsin deficiency and its clinical consequences

Alpha-1-antitrypsin deficiency (AATD) is a genetic disorder that manifests as pulmonary emphysema, liver cirrhosis and, rarely, as the skin disease panniculitis, and is characterized by low serum levels of AAT, the main protease inhibitor (PI) in human serum. The prevalence in Western Europe and in the USA is estimated at approximately 1 in 2,500 and 1 : 5,000 newborns, and is highly dependent on the Scandinavian descent within the population. The most common deficiency alleles in North Europe are PI Z and PI S, and the majority of individuals with severe AATD are PI type ZZ. The clinical manifestations may widely vary between patients, ranging from asymptomatic in some to fatal liver or lung disease in others. Type ZZ and SZ AATD are risk factors for the development of respiratory symptoms (dyspnoea, coughing), early onset emphysema, and airflow obstruction early in adult life. Environmental factors such as cigarette smoking, and dust exposure are additional risk factors and have been linked to an accelerated progression of this condition. Type ZZ AATD may also lead to the development of acute or chronic liver disease in childhood or adulthood: prolonged jaundice after birth with conjugated hyperbilirubinemia and abnormal liver enzymes are characteristic clinical signs. Cirrhotic liver failure may occur around age 50. In very rare cases, necrotizing panniculitis and secondary vasculitis may occur. AATD is caused by mutations in the SERPINA1 gene encoding AAT, and is inherited as an autosomal recessive trait. The diagnosis can be established by detection of low serum levels of AAT and isoelectric focusing. Differential diagnoses should exclude bleeding disorders or jaundice, viral infection, hemochromatosis, Wilsons disease and autoimmune hepatitis. For treatment of lung disease, intravenous alpha-1-antitrypsin augmentation therapy, annual flu vaccination and a pneumococcal vaccine every 5 years are recommended. Relief of breathlessness may be obtained with long-acting bronchodilators and inhaled corticosteroids. The end-stage liver and lung disease can be treated by organ transplantation. In AATD patients with cirrhosis, prognosis is generally grave.

Neutrophil serine proteinases and defensins in chronic obstructive pulmonary disease: effects on pulmonary epithelium

Neutrophils have the capacity to accumulate in high numbers in the lung during infection and inflammation. Because they play an important role in host defence against infection, but may also cause tissue injury, these cells are thought to be involved in the pathogenesis of various inflammatory lung disorders, including chronic bronchitis and chronic obstructive pulmonary disease. Neutrophil products that may mediate tissue injury at sites of neutrophil-dominated inflammation include the neutrophil serine proteinases elastase, cathepsin G and proteinase 3, and the nonenzymatic defensins. One of the targets of the neutrophil is the lung epithelium, and in vitro studies have revealed that both the serine proteinases and neutrophil defensins markedly affect the integrity of the epithelial layer, decrease the frequency of ciliary beat, increase the secretion of mucus, and induce the synthesis of epithelium-derived mediators that may influence the amplification and resolution of neutrophil-dominated inflammation. Both neutrophil elastase and defensins induce the release of the neutrophil chemoattractant chemokine interleukin-8 from respiratory epithelial cells. The alpha1-proteinase inhibitor (alpha1-PI) is a well-characterized inhibitor of neutrophil elastase, that also blocks the cytotoxic and stimulatory activity of defensins towards epithelial cells. The elastase inhibitory activity of alpha1-PI is also abrogated by the binding of defensins to this inhibitor. Incubation of epithelial cells with neutrophil defensins in combination with either elastase or cathepsin G resulted in decreased effects on the epithelial cells compared with those observed when the cells were incubated with defensins, elastase or cathepsin G separately. These results suggest that neutrophil defensins and serine proteinases cause injury and stimulate epithelial cells to produce chemokines that attract more neutrophils to the site of inflammation. The effects of neutrophil defensins and serine proteinases on epithelial cells appear to be restricted by proteinase inhibitors and by inhibitory interactions between these sets of neutrophil granule proteins.

Is there any relationship between plasma antioxidant capacity and lung function in smokers and in patients with chronic obstructive pulmonary disease

BACKGROUND It has been suggested that oxidative stress is an important factor in the pathogenesis of chronic obstructive pulmonary disease (COPD). We have shown that an oxidant/antioxidant imbalance occurs in the distal air spaces of smokers and in patients with COPD which is reflected systemically in the plasma. A study was undertaken to determine whether plasma antioxidant status correlated with lung function as assessed by forced expiratory volume in one second (FEV1) and forced vital capacity (FVC) in smokers and patients with COPD. METHODS Plasma antioxidant capacity, assessed by the Trolox equivalent antioxidant capacity (TEAC) as an index of overall systemic oxidative stress, and protein thiol levels were measured in 95 patients with stable COPD, in 82 healthy smokers, and in 37 healthy non-smokers. RESULTS Mean (SE) plasma TEAC levels were significantly decreased in patients with COPD (0.81 (0.03) mmol/l, p<0.001) and in healthy smokers (0.87 (0.04) mmol/l, p<0.001) compared with healthy non-smokers (1.31 (0.11) mmol/l). The mean differences in plasma antioxidant capacity (mM) were (0.81, 95% confidence interval (CI) 0.22 to 1.48), (0.87, 95% CI 0.2 to 1.46), and (1.31, 95% CI 1.09 to 1.58) in patients with COPD, healthy smokers, and healthy non-smokers, respectively. This reduction was associated with a 29% (95% CI 18 to 38) and a 30% (95% CI 19 to 40) decrease in plasma protein thiol levels in COPD patients and smokers, respectively. Current smoking was not the main contributor to the reduction in antioxidant capacity in patients with COPD as those patients who were still smokers had similar TEAC levels (mean (SE) 0.78 (0.05); n = 25) to those who had stopped smoking (0.84 (0.02); n = 70). No significant correlations were found between spirometric data measured as FEV1 % predicted or FEV1/FVC % predicted and the plasma levels of TEAC in patients with COPD, healthy smokers, or healthy non-smokers. Similarly, there was no significant correlation between FEV1 % predicted or FEV1/FVC % predicted and the levels of plasma protein thiols in the three groups. CONCLUSIONS These data confirm decreased antioxidant capacity in smokers and patients with COPD, indicating the presence of systemic oxidative stress. However, no relationship was found between protein thiols or TEAC levels and measurements of airflow limitation in either smokers or in patients with COPD.

Validation of computed tomographic lung densitometry for monitoring emphysema in α1-antitrypsin deficiency

Background: Lung densitometry derived from computed tomographic images offers an opportunity to quantify emphysema non-invasively, but a pathological standard cannot be applied to validate its use in longitudinal monitoring studies. Consequently, forced expiratory volume in 1 second (FEV1) remains the standard against which new methods must be judged. We related progression of densitometry (15th percentile point and voxel index, threshold −950 Hounsfield units) to disease stage and FEV1 decline in two studies of subjects with α1-antitrypsin deficiency (PiZ). Methods: Consistency of progression, measured using densitometry and FEV1, was assessed in relation to disease stage in a 2 year study of 74 subjects grouped according to the FEV1 criteria employed in the GOLD guidelines. In the second study of a subgroup of subjects with extended data (n = 34), summary statistics were applied to measurements performed annually over 3 years and the rate of progression of densitometry was related to FEV1 decline. Results: The progression of percentile point was consistent across a wide spectrum of disease severity, but voxel index progression varied in association with disease stage (p = 0.004). In the second study, FEV1 decline correlated with progression of lung densitometry (percentile point: rS = 0.527, p = 0.001; voxel index: rS = −0.398, p = 0.012). Conclusions: 15th percentile point is a more consistent measure of lung density loss across a wide range of physiological impairment than voxel index. However, both methods are valid for use in longitudinal and interventional studies in which emphysema is the major outcome target.

A quantitative method for detection of spliced X-box binding protein-1 (XBP1) mRNA as a measure of endoplasmic reticulum (ER) stress

Endoplasmic reticulum (ER) stress is increasingly recognized as an important mechanism in a wide range of diseases including cystic fibrosis, alpha-1 antitrypsin deficiency, Parkinsons and Alzheimers disease. Therefore, there is an increased need for reliable and quantitative markers for detection of ER stress in human tissues and cells. Accumulation of unfolded or misfolded proteins in the endoplasmic reticulum can cause ER stress, which leads to the activation of the unfolded protein response (UPR). UPR signaling involves splicing of X-box binding protein-1 (XBP1) mRNA, which is frequently used as a marker for ER stress. In most studies, the splicing of the XBP1 mRNA is visualized by gel electrophoresis which is laborious and difficult to quantify. In the present study, we have developed and validated a quantitative real-time RT-PCR method to detect the spliced form of XBP1 mRNA.

Expression of Epidermal Growth Factors and Their Receptors in the Bronchial Epithelium of Subjects With Chronic Obstructive Pulmonary Disease

Smoking may affect epithelial repair and differentiation differentially in smokers with and without chronic obstructive pulmonary disease (COPD). We hypothesized that epithelial repair is disturbed in patients with COPD owing to higher expression of epidermal growth factor (EGF)-like factors and/or receptors. We studied epithelial expression of EGF, transforming growth factor a, amphiregulin, heregulin (HRG), betacellulin (BTC), and their receptors, EGFR, HER-2, and HER-3, by immunohistochemical analysis in resected bronchial tissue from 20 subjects with (forced expiratory volume in 1 second [FEV(1)] <75% of predicted value) and 18 without (FEV(1) >85% predicted value) COPD. All subjects underwent surgery for lung cancer. The proportion of intact, damaged, goblet, or squamous metaplastic epithelium was similar in subjects with and without COPD. Regardless of smoking status, HRG expression was higher in intact epithelium of patients with COPD than in those without. Subgroup analysis showed higher EGFR expression in intact epithelium (1.4 times; P pound .04) and higher EGF, BTC, and HRG expression in damaged epithelium (1.4-1.8 times; P<or=.05) of ex-smokers with COPD compared with ex-smokers without COPD. These data support our hypothesis and suggest that current smoking obscures intrinsically higher expression in COPD.

Optimization and standardization of lung densitometry in the assessment of pulmonary emphysema.

Currently, lung densitometry for the assessment of pulmonary emphysema has been fully validated against pathology, pulmonary function, and health status, and it is therefore being applied in pharmacotherapeutic trials. Nevertheless, its application for the early detection of emphysema has not yet been introduced in daily clinical practice. The main reason for this is the fact that it is not yet regarded a fully optimized and standardized technique. In this work, an overview is given on the current status of different standardization aspects that play an important role in this, ie, image acquisition, choice of densitometric parameter and image processing. To address these issues, solutions have been sought from the literature and from original data from previous studies. Standardization and optimization of lung densitometry has reached a more advanced stage than has been reported so far. If normal values will become available, this technique will be feasible for clinical practice. As a result, standardization for the detection and assessment of other density-related lung diseases can be achieved in a shorter period of time.

Effect of apocynin on ozone-induced airway hyperresponsiveness to methacholine in asthmatics.

Apocynin is an inhibitor of NADPH oxidase present in inflammatory cells such as eosinophils and neutrophils. We investigated the effect of inhaled apocynin on ozone-induced bronchial hyperresponsiveness in vivo. Seven mild atopic asthmatics participated in a placebo-controlled, cross-over study with two exposures to O(3) at 2-week intervals. Apocynin (3 ml of 0.5 mg/ml) was inhaled 2 times before and 6 times after O(3) exposure at hourly intervals. At 36 h before and 16 h after O(3) exposure, methacholine inhalation challenge tests (Mch) were performed, and PC(20) and maximal % fall from baseline (MFEV(1)) were calculated from dose-response curves. O(3)-induced change in PC(20) (Delta PC(20)) after placebo treatment was -1.94 +/- 0.39 DD (mean +/- SEM doubling dose Mch) (p =.001) and apocynin was -0.6 +/- 0.33 DD (p =.17). The difference between apocynin and placebo treatment was 1.3 DD +/- 0.42 (p =.02). O(3)-induced Delta MFEV(1) was 11.9 +/- 1.5% (p =.008) during placebo inhalation and 3.85 +/- 1.8% during apocynin (p =.47). Apocynin reduced the Delta MFEV(1) by 8.05% compared to placebo (p =.025). We conclude that apocynin markedly reduced O(3)-induced hyperreactivity for Mch as well as maximal airway narrowing. The results suggest that apocynin may have a role in preventing ozone-induced exacerbations of asthma.

Apocynin increases glutathione synthesis and activates AP‐1 in alveolar epithelial cells

Apocynin (4‐hydroxy‐3‐methoxy‐acetophenone) is a potent intracellular inhibitor of superoxide anion production in neutrophils. In this study, we studied the effect of apocynin on the regulation of the antioxidant glutathione (GSH) and activation of the transcription factor AP‐1 in human alveolar epithelial cells (A549). Apocynin enhanced intracellular GSH by increasing γ‐glutamylcysteine synthetase activity in A549 cells. Apocynin also increased the expression of γ‐GCS heavy subunit mRNA. This was associated with increased AP‐1 DNA binding as measured by the electrophoretic mobility shift assay. These data indicate that apocynin displays antioxidant properties, in part, by increasing glutathione synthesis through activation of AP‐1.