Upregulation of adhesion molecules in the bronchial mucosa of subjects with chronic obstructive bronchitis

Evolving concepts in the pathogenesis of chronic obstructive pulmonary disease

It is arguable that more biologic insight has been gained from the study of COPD than from any other pulmonary disorder. A vast knowledge of the biology of extracellular matrix proteins, proteinases, and proteinase inhibitors has largely stemmed from the elastase:anti-elastase hypothesis for the pathogenesis of emphysema. An equally compelling case could be made that interest in, and funding for, COPD research has been woeful, and investigators have made no significant medical breakthroughs in the treatment of this disorder, which, unfortunately, is becoming epidemic worldwide. Indeed, it cannot be argued that physicians have very little treatment to offer to the many patients with COPD. Humankind is rapidly approaching a time when all human genes will be sequenced, and genetic engineering will allow determination of the function of these proteins in vivo. Expression profiling and bioinformatics will allow clinicians to assess the spectrum of genes and proteins regulated in biologic processes, no longer limiting study to naïve candidate genes. These advances will allow investigators to decipher precise pathways of complex diseases, identify genetic and environmental interactions, and ultimately lead to specific (pre)diagnoses and rational treatment. Answers to the question as to why only a subset of smokers develop COPD will enhance the understanding of the disease process. Fortunately, there has been a resurgence of interest in COPD, led largely by the pharmaceutical industry, which has discovered the potential of this unmet need. Consequently, these state-of-the-art scientific techniques are being directly applied to COPD, lending hope for the future. Of even greater importance, the tide seems to be turning on the cigarette industry. Although difficult to imagine, perhaps cigarettes will disappear in this lifetime or at least the next generation won't be fooled by this deadly habit! Well ... the rational therapy thing could work.

Endothelial sulfated sialyl Lewis x glycans, putative L-selectin ligands, are preferentially expressed in bronchial asthma but not in other chronic inflammatory lung diseases

Lymphocyte infiltrate is a hallmark of inflammatory responses. We have previously shown that de novo-induced endothelial sialyl Lewis x (sLex) expression guides lymphocytes in an L-selectin-dependent manner to sites of acute organ transplant rejections. In this research, we have analyzed five groups of chronic lung inflammations to determine the presence of properly glycosylated, i.e., sulfated, sLex-decorated, L-selectin ligands. Two anti-sLex (2F3 and HECA-452) and one anti-6- and/or 6'-sulfated and/or 6,6'-bisulfated (MECA-79) monoclonal antibodies (mAbs) were used. The control lung specimens did not express L-selectin ligands on endothelium. In contrast, the endothelial staining intensity and the number of positive peribronchial venules and capillaries with mAbs 2F3, HECA-452, and MECA-79 were significantly greater in bronchial biopsies from patients with asthma compared with normal specimens (P<0.003). However, no significant increase of peribronchial endothelial reactivity with these antibodies was observed in adult respiratory distress syndrome, chronic bronchitis, fibrosing alveolitis, and granulomatous inflammation compared with controls. These data suggest that sulfated sLex glycans, acting putatively as ligands for L-selectin, could be instrumental in lymphocyte extravasation into human peribronchial lung tissue during asthma, but not so important in several other inflammatory lung diseases.

Serum ECP and MPO are increased during exacerbations of chronic bronchitis with airway obstruction

Many studies have demonstrated that, in asthma, serum levels of eosinophil cationic protein (ECP) are related to the activity and severity of the disease and can be used to evaluate the response to steroid treatment. During exacerbations of chronic bronchitis, airway inflammation shows some features of asthmatic inflammatory processes, with recruitment of eosinophils and recovery of significant amounts of ECP in bronchial lavage fluid (BAL). Involvement of neutrophils, with high levels of myeloperoxidase (MPO), is, on the contrary, typical of this latter disease, and not shared with asthma. In spite of the information collected with BAL and bronchial biopsy studies, few data still exist on serum levels of these proteins in chronic bronchitis. The objective of this study was to assess if serum levels of ECP and MPO are specifically increased in exacerbations of chronic bronchitis, as compared to other non-asthmatic acute respiratory disturbances. Serum ECP, MPO and immunoglobulin E (IgE) levels were measured in 17 non-atopic patients with exacerbation of chronic bronchitis with airway obstruction (COPD) and in 11 control subjects seeking emergency medical treatment for unrelated acute respiratory problems. Spirometry was performed in patients able to give the necessary collaboration. All the subjects of this study were recruited from the emergency department. Both ECP and MPO were significantly increased in serum from patients with exacerbated COPD (22.2 +/- 4.1 vs 9.5 +/- 1.4 mcg/L and 853 +/- 168 vs 375 +/- 41 mcg/L) and a strong correlation existed between these two variables (r = 0.782). A further control group was made of 11 patients with stable COPD. These subjects had levels of both ECP (13.1 +/- 2.7 mcg/L) and MPO (469 +/- 71) significantly lower than patients with exacerbated disease and higher than those without COPD. We conclude that serum ECP and MPO are increased during the exacerbations of COPD. These observations can give a basis for further studies aimed to evaluate the utility of these two proteins as markers of activity and severity of COPD.

Comparison of the structural and inflammatory features of COPD and asthma. Giles F. Filley Lecture

At least three conditions contribute to COPD. (1) Chronic bronchitis (mucous hypersecretion) is an inflammatory condition in which CD8+ T-lymphocytes, neutrophils, and CD68+ monocytes/macrophages predominate. The condition is defined clinically by the presence of chronic cough and recurrent increases in bronchial secretions sufficient to cause expectoration. There is enlargement of mucus-secreting glands and goblet cell hyperplasia, which can occur in the absence of airflow limitation. (2) Adult chronic bronchiolitis (small or peripheral airways disease) is an inflammatory condition of small bronchi and bronchioli in which there are predominantly CD8+ and pigmented macrophages. The functional defect is difficult to detect clinically but may be recognized by sophisticated tests of small airway function. There is mucous metaplasia, enlargement of the mass of bronchiolar smooth muscle, and loss of alveolar attachments. (3) Emphysema is an inflammatory condition of the alveoli in which T-lymphocytes, neutrophils, and pigmented alveolar macrophages are involved, associated with the release of excessive amounts of elastases. It is defined anatomically by permanent, destructive enlargement of airspaces distal to terminal bronchioli without obvious fibrosis. In contrast, asthma is a clinical syndrome characterized by allergic inflammation of bronchi and bronchioli in which CD4+ (helper) T-lymphocytes and eosinophils predominate. There is increased production and release of interleukin (IL)-4 and IL-5, which is referred to as a Th2-type response. There is usually increased tracheobronchial responsiveness to a variety of stimuli, and the condition is usually manifest as variable airflow obstruction. While differences between COPD and asthma have been highlighted, new data are emerging that indicate there may also be similarities.

Human bronchial intraepithelial T lymphocytes as a distinct T-cell subset: their long-term survival in SCID-Hu chimeras

Intestinal intraepithelial T lymphocytes (i-IELs) show features different from those of conventional T cells and play specific roles in the mucosal immunity. To investigate whether human bronchial intraepithelial T lymphocytes (IELs) are a distinct entity, we examined T cells in human bronchial xenografts transplanted on mice with severe combined immune deficiency (SCID). We transplanted human bronchi subcutaneously into mice with SCID, resected the xenografts after various incubation periods (7-174 d), and examined them for CD3(+), CD4(+), CD8(+), and CD45(+) cells by immunohistochemistry. The number of CD3(+) cells in the lamina propria decreased significantly in the first month (from 308.7 +/- 60.2 to 70.9 +/- 49. 4/mm(2); P < 0.05), and xenografts more than 5 mo of age had scant T cells in the lamina propria (5.2 +/- 2.0/mm(2)). However, there was no significant difference between the number of CD3(+) IELs in freshly isolated bronchi and in xenografts maintained for more than 5 mo. In freshly isolated bronchi, the number of CD4(+) IELs was significantly lower than that of CD8(+) cells (2.35 +/- 0.62 versus 4.56 +/- 1.32/mm basement membrane; P < 0.01). After transplantation, the mean CD4-to-CD8 ratio of all xenografts was significantly higher than that of freshly isolated bronchi (5.2 +/- 0.9 versus 0.6 +/- 0.2; P < 0.005). The IELs were positive for CD45, which is specific for human leukocytes, and they were eliminated by irradiation before the transplantation. Almost all IELs (99.5%) in the xenografts expressed alphabeta T-cell receptor, and 35.8% of IELs expressed alpha(e)beta7 integrin. Bronchial epithelial cells in the xenografts expressed interleukin (IL)-7, stem cell factor, intercellular adhesion molecule (ICAM)-1, and human leukocyte antigen-DR (HLA-DR). We conclude that in the SCID-Hu chimera model, human bronchial IELs survive for more than 5 mo, unlike the T cells in the lamina propria, and we suggest that human bronchial IELs may be stimulated by bronchial epithelial cells expressing IL-7, stem cell factor, ICAM-1, and HLA-DR.

Upregulation of gelatinases A and B, collagenases 1 and 2, and increased parenchymal cell death in COPD

BACKGROUND

A central feature in the pathogenesis of COPD is the inflammation coexisting with an abnormal protease/antiprotease balance. However, the possible role of different serine and metalloproteinases remains controversial.

PATIENTS AND MEASUREMENTS

We examined the expression of gelatinases A and B (matrix metalloproteinase [MMP]-2 and MMP-9); collagenases 1, 2, and 3 (MMP-1, MMP-8, and MMP-13); as well as the presence of apoptosis in lung tissues of 10 COPD patients and 5 control subjects. In addition, gelatinase-A and gelatinase-B activities were assessed in BAL obtained from eight COPD patients, and from six healthy nonsmokers and six healthy smoker control subjects.

SETTING

Tertiary referral center and university laboratories of biochemistry, and lung cell kinetics.

RESULTS

Immunohistochemical analysis of COPD lungs showed a markedly increased expression of collagenases 1 and 2, and gelatinases A and B, while collagenase 3 was not found. Neutrophils exhibited a positive signal for collagenase 2 and gelatinase B, whereas collagenase 1 and gelatinase A were revealed mainly in macrophages and epithelial cells. BAL gelatin zymography showed a moderate increase of progelatinase-A activity and intense bands corresponding to progelatinase B. In situ end labeling of fragmented DNA displayed foci of positive endothelial cells, although some alveolar epithelial, interstitial, and inflammatory cells also revealed intranuclear staining.

CONCLUSION

These findings suggest that there is an upregulation of collagenase 1 and 2 and gelatinases A and B, and an increase in endothelial and epithelial cell death, which may contribute to the pathogenesis of COPD through the remodeling of airways and alveolar structures.

New approaches to the management of COPD

Airflow limitation in COPD is a result partially of bronchospasm, but it is also caused by a reduction in airway caliber, the number of small airways, airway collapse because of loss of connective tissue support, excess mucus in the airways, and edema of the airway wall. Structural changes also occur because of long-term destruction of interstitial connective tissue, including elastin. Therefore, in addition to the traditional aim of reversing bronchospasm with bronchodilators, disease-modifying approaches are being investigated. The enzyme neutrophil elastase is implicated in the induction of bronchial disease causing structural changes in lungs, impairment of mucociliary clearance, and impairment of host defenses. The precise mechanism pathway of neutrophil elastase is uncertain, but the effects of influencing the pathway in order to slow disease progression are being investigated. Oxidants may also have a role in the development of COPD, with increased levels activating airway cells and cytokine production.

Inflammation markers in the serum of salt miners

The inflammation markers alpha-1-antitrypsin (AAT), Clara cell protein (CC-16), soluble interleukin-2-receptor (IL-R) and the soluble adhesion molecule E-selectin, the intercellular adhesion molecule (ICAM-1) and the vascular adhesion molecule (VCAM-1) were determined in the serum of 195 salt-exposed miners to analyse dose-response relationships between markers and potash dust. Alpha-1-antitrypsin, Clara-cell protein, IL2-R, E-selectin and VCAM-1 were not changed by salt exposure, however the ICAM-1 level in the serum fell slightly as the salt exposure increased. This effect was strongest in the group of smokers, still visible in the group of ex-smokers, no effect was seen in non-smokers. Markers, with the exception of VCAM-1, were influenced by tobacco exposure. Since markers were not elevated in relation to salt dust exposure, the results do not support an inflammatory effect of potash dust on the respiratory system.

Chronic obstructive pulmonary disease. Inflammation of small airways and lung parenchyma

Currently available information suggests that cigarette smoke-induced lung inflammation has a pathogenic role in the development of COPD. Neutrophils, eosinophils, alveolar macrophages, and lymphocytes all appear to participate in the inflammatory process. However, the respective importance of these cells and their level of activation are difficult to quantitate because disease phenotyping, and compartmentalization of inflammation and markers of inflammation in the lung, influence the obtained data and bias their interpretation. Bronchoscopic biopsies are typically obtained from larger, cartilaginous airways containing submucosal glands whereas the site of airflow obstruction in COPD is predominantly the membranous bronchiole, devoid of cartilage and submucosal glands. This makes it difficult to establish structure-function relationships. The proportion of neutrophils has been reported to increase in repeated induced sputum and bronchoalveolar lavage samples. This observation suggests neutrophil recruitment into the airway is induced by the tests or sampling of different airway compartments in subsequent tests. There appears to be a good correlation between the proportions of eosinophils in induced sputum and bronchoalveolar lavage fluid on the one hand and in airway tissue on the other. However, this is not the case for other inflammatory cells, especially T lymphocytes, which are more numerous in airway tissue. Despite these inconsistencies, induced sputum, bronchoalveolar lavage, and bronchial biopsies can be used as markers of inflammation in COPD as long as their limitations are recognized. Cosio MG, Guerassimov A. Chronic obstructive pulmonary disease: inflammation of small airways and lung parenchyma.

Airway inflammation in chronic obstructive pulmonary disease

Cigarette smoking causes an inflammatory process in the central airways, peripheral airways, and lung parenchyma, even in smokers with normal lung function. The characteristics of this inflammatory process differ between smokers who develop chronic airflow limitation (COPD) and those who do not develop chronic airflow limitation: there is an increased infiltration of CD8-positive T lymphocytes in smokers with COPD. We examine whether airway inflammation alters with increasing severity of disease. When the disease becomes severe, a prominent neutrophilia occurs. The precise roles of the CD8(+) T lymphocyte and the neutrophil in the pathogenesis of COPD still remain to be determined. Saetta M. Airway inflammation in chronic obstructive pulmonary disease.

Novel approaches and targets for treatment of chronic obstructive pulmonary disease

There is a driving need to develop new and effective treatments for COPD. Bronchodilators are now the mainstay of symptomatic therapy and a new long-acting anticholinergic bronchodilator, tiotropium bromide, is now in advanced clinical trials as a once daily dry powder inhaler. Several inflammatory mediators are involved in the chronic neutrophilic inflammation that typifies COPD, including leukotriene B(4) and interleukin 8, for which specific receptor antagonists have been developed. Since the inflammatory process in COPD is essentially steroid resistant, new antiinflammatory treatments are needed. Drugs that may be effective include phosphodiesterase 4 inhibitors, NF-kappaB inhibitors, and interleukin 10. Inhibition of proteases is another approach and inhibitors of neutrophil elastase, cathepsins, and matrix metalloproteases are now in clinical development. Supply of endogenous antiproteases, such as alpha(1)-antitrypsin and secretory leukocyte protease inhibitors as recombinant proteins or by gene transfer, is also being explored. In future drugs that may stimulate alveolar repair might be developed, including retinoid receptor agonists and hepatic growth factor. Future directions will include earlier detection of disease, gene profiling to identify which smokers are at risk of COPD, and the development of noninvasive surrogate markers to monitor disease activity in order to monitor new therapies. Identification of genes that confer a risk for COPD in smokers may identify novel targets for drug development. Barnes PJ. Novel approaches and targets for treatment of chronic obstructive pulmonary disease.

Neutrophils and protease/antiprotease imbalance

An imbalance between neutrophil proteases and the surrounding antiproteases is critical in the normal functioning of the neutrophil. Enzyme activity is of importance in cell migration and may play a role in some beneficial aspects of host defense. However, when persistent or excessive this imbalance can be detrimental and (even in the absence of antiprotease deficiency) central to most of the pathogenic processes in COPD. Understanding of these complex relationships that alter a beneficial host defense response to a destructive one will be critical in the development of long-term therapeutic strategies. Stockley RA. Neutrophils and protease/antiprotease imbalance.

Inflammatory reaction in pulmonary muscular arteries of patients with mild chronic obstructive pulmonary disease

Endothelial dysfunction and intimal thickening have been shown in pulmonary arteries (PA) of patients with mild chronic obstructive pulmonary disease (COPD). To investigate whether an inflammatory process related to tobacco smoking might be involved in the development of pulmonary vascular abnormalities in COPD, we characterized the inflammatory cell infiltrate and the endothelium-dependent relaxation in PA of 39 patients who underwent lung resection, divided into three groups: "nonsmokers" (n = 7); "smokers," with normal lung function (n = 12); and "COPD" (n = 20). Endothelium-dependent relaxation was assessed in vitro by exposing PA rings to adenosine diphosphate (ADP). Inflammatory cell types were identified by immunohistochemistry. PA of COPD patients developed lower relaxation in response to ADP than nonsmokers and smokers. The number of inflammatory cells was increased in PA of COPD compared with the other two groups. This cell infiltrate was largely constituted by T lymphocytes. The CD8(+) T-cell subset was increased in both smokers and COPD compared with nonsmokers, yielding a reduction of the CD4(+)/CD8(+) ratio. The intensity of the inflammatory infiltrate correlated with both the endothelium-dependent relaxation and the intimal thickness. We conclude that cigarette smoking induces a CD8(+) T-lymphocyte infiltrate in PA, which is associated with the impairment of the vessel's structure and function, suggesting the potential involvement of an inflammatory process in the pathogenesis of pulmonary vascular abnormalities in the early stage of COPD.

Transforming growth factor beta1 and recruitment of macrophages and mast cells in airways in chronic obstructive pulmonary disease

Chronic airways inflammation is one of the features of chronic obstructive pulmonary disease (COPD). We demonstrated previously that bronchiolar epithelium in COPD contains increased numbers of macrophages and mast cells. Transforming growth factor beta1 (TGF-beta1) may be involved in this influx because it has chemotactic activity for macrophages and mast cells. In this study, we examined expression patterns of TGF-beta1, TGF-beta receptors type I and II (TGF-betaRI and TGF-betaRII) by immunohistochemistry and mRNA in situ hybridization in peripheral lung tissue of 14 current or ex-smokers with COPD (FEV1 < 75%) and 14 without COPD (FEV1 > 84%). In both groups, TGF-beta1 and its receptors are present in airway and alveolar epithelial cells, airway and vascular smooth muscle cells, and tissue and alveolar CD68(+) cells (considered herein to be macrophages). In subjects with COPD, a semiquantitative analysis revealed approximately twofold higher levels of TGF-beta1 mRNA and protein in bronchiolar and alveolar epithelium (p < 0.02) as compared with subjects without COPD. With regard to bronchiolar epithelial cells, we found a significant correlation between TGF-beta1 mRNA and protein expression (r = 0.62; p < 0.002), and between the FEV1 of all subjects together and TGF-beta1 protein (r = -0.60; p < 0.0002) and mRNA (r = -0.67; p < 0. 002) levels. The epithelial expression of TGF-beta1 mRNA and TGF-beta1 protein correlates with the number of intraepithelial macrophages (both: r = 0.44; p < 0.03) whereas intraepithelial mast cell numbers correlate with epithelial TGF-beta1 mRNA expression. These data suggest a role for TGF-beta1 in recruiting macrophages into the airway epithelium in COPD.

Expression of adhesion molecules and G proteins in circulating neutrophils in chronic obstructive pulmonary disease

We investigated the expression of adhesion molecules in circulating neutrophils (lymphocyte function-associated antigen-1 [LFA-1], Mac-1, and L-selectin) and endothelial cells (soluble intercellular adhesion molecule-1[sICAM-1]) in 23 patients with stable chronic obstructive pulmonary disease (COPD), 18 subjects with exacerbated COPD, and 23 healthy volunteers. Also, in these circulating neutrophils, we assessed the expression of two G protein subunits (Galphas and Galphai1/2). Compared with control subjects, patients with stable COPD showed increased expression of Mac-1 (p < 0.001) and lower levels of sICAM-1 (p = 0.002); LFA-1 and L-selectin expression was similar in patients and control subjects. During exacerbations, compared with stable patients, the expression of Mac-1 and LFA-1 was reduced (p < 0.001). Finally, the expression of Galphas (but not Galphai1/2) was also reduced (p < 0.001) in circulating neutrophils of patients with COPD, irrespective of the clinical condition of the patient. These results indicate that in patients with COPD: (1) the expression of some neutrophil adhesion molecules (Mac-1) is abnormal, and that this pattern changes during exacerbations; (2) there may be a form of endothelial dysfunction, as suggested by the low sICAM-1 levels; (3) the expression of G protein subunit (Galphas) in circulating neutrophils is downregulated, irrespective of their clinical conditions. Overall, these results indicate the presence of significant systemic abnormalities in COPD.

Are chronic obstructive pulmonary disease (COPD) and asthma different diseases?

In the past it has been hypothesized that asthma and chronic obstructive pulmonary disease (COPD) are related diseases. As both show high prevalences and as smoking may occur in both groups of patients the simultaneous presence of both diseases in the same subject may well occur. The most characteristic features of asthma are short-term changes in airway caliber, reversible airflow limitation, bronchial hyperresponsiveness as well as eosinophilic and lymphocytic airway inflammation. The common definition of COPD implies long-term changes in airway calibre, less or irreversible airflow obstruction, no or less common bronchial hyperresponsiveness and neutrophilic airway inflammation. By analysing the results of epidemiology, risk factors, airway morphology, lung function and markers of airway inflammation in both diseases, it becomes clear that asthma and COPD share some similarities. However, their pathological presentations differ considerably and this provides evidence that the two syndromes are, in fact, different diseases. Furthermore, the analysis of data on lung volumes, diffusion capacity and aerosol-derived airway morphology shows important differences between asthma and COPD. It is suggested that the specific type of airway inflammation in both diseases is responsible for the peculiar pattern of lung function abnormalities.

Severity of airflow limitation is associated with severity of airway inflammation in smokers

To investigate the relationship between airflow limitation and airway inflammation in smokers, we examined paraffin-embedded bronchial biopsies obtained from 30 smokers: 10 with severe airflow limitation, eight with mild/moderate airflow limitation, and 12 control smokers with normal lung function. Histochemical and immunohistochemical methods were performed to assess the number of inflammatory cells in the subepithelium and the expression of CC chemokines macrophage inflammatory protein (MIP)-1alpha and -1beta in the bronchial mucosa. Compared with control smokers, smokers with severe airflow limitation had an increased number of neutrophils (p < 0.02), macrophages (p < 0.03), and NK lymphocytes (p < 0.03) in the subepithelium, and an increased number of MIP-1alpha+ epithelial cells (p < 0.02). When all smokers were considered together, the value of FEV1 was inversely correlated with the number of neutrophils (r = -0.59, p < 0.002), macrophages (r = -047, p < 0. 012), NK-lymphocytes (r = -0.51, p < 0.006) in the subepithelium, and with the number of MIP-1alpha+ epithelial cells (r = -0.61, p < 0.003). We conclude that in smokers the severity of airflow limitation is correlated with the severity of airway inflammation and that severe airflow limitation is associated with an increased number of neutrophils, macrophages, NK lymphocytes, and MIP-1alpha+ cells in the bronchial mucosa.

Neutrophil-dependent goblet cell degranulation: role of membrane-bound elastase and adhesion molecules

We examined the effect of the neutrophil chemoattractants interleukin (IL)-8 and N-formyl-methionyl-leucyl-phenylalanine on goblet cell (GC) degranulation in guinea pigs. Chemoattractants caused time-dependent neutrophil recruitment and GC degranulation in vivo. NPC 15669 (an inhibitor of leukocyte infiltration) prevented both responses, implicating neutrophils. ICI 200,355 (an inhibitor of neutrophil elastase and proteinase-3) or secretory leukocyte protease inhibitor (an inhibitor of elastase but not of proteinase-3) abolished IL-8-induced GC degranulation, implicating elastase. Incubating tracheal segments with IL-8 plus neutrophils caused GC degranulation in vitro, an effect due to activation of the neutrophils themselves (and not an effect present in the supernatant). Chemoattractant increased surface staining of elastase and the cleavage of elastase-specific fluorogenic substrate by neutrophils. Pretreatment with anti-intercellular adhesion molecule-1, anti-CD18, or anti-CD11b antibody inhibited the chemoattractant-induced GC degranulation in vitro, implicating adhesion molecules. These studies suggest that chemoattractants cause neutrophil-dependent GC degranulation involving adhesive interactions between cells, with elastase activity occurring at the cell interface, causing GC secretion. The findings, reproduced in human airways, suggest novel methods of therapeutic intervention.

Neutrophils infiltrating bronchial epithelium in chronic obstructive pulmonary disease

In order to characterize neutrophil and eosinophil presence in the airways of patients with chronic obstructive pulmonary disease (COPD), bronchoscopy with bronchial washings and bronchial biopsies was performed in 12 smoking stable COPD subjects and 18 normal non-smoking control subjects. Bronchial biopsies were examined by light microscopy using plastic embedding and histochemical techniques to identify different cell types. Bronchial washing fluid of COPD patients was characterized by a predominance of neutrophils (P = 0.001), and a slight, but significant (P = 0.03), increase of eosinophil fraction. Subjects with COPD had higher number of neutrophils in the epithelium (P = 0.01), and eosinophils in the lamina propria (P = 0.01) than did control subjects. The thickness of reticular basement membrane was increased for COPD patients in comparison to control subjects (P = 0.01). The present study provides evidence of neutrophil infiltration both in bronchial washing and bronchial epithelium of patients with COPD, suggesting that the source of neutrophils in airway lumen may be the bronchial mucosa. Although less common than in asthma, airways of COPD subjects reveal eosinophil presence and airway remodelling.

The role of infection in COPD

Clinical studies of acute exacerbations of COPD are difficult because of the heterogeneous nature of COPD, diffuse symptoms that can vary spontaneously, and difficulties in defining clinical response both in the short and long term. The role of bacterial infection, and thus use of antibiotics, in COPD is controversial. The available evidence shows that bacterial infection has a significant role in acute exacerbations, but its role in disease progression is less certain. Upper respiratory tract commensals, such as nontypable Haemophilus influenzae, cause most bronchial infections by exploiting deficiencies in the host defenses. Some COPD patients are chronically colonized by bacteria between exacerbations, which represents an equilibrium in which the numbers of bacteria are contained by the host defenses but not eliminated. When an exacerbation occurs, this equilibrium is upset and bacterial numbers increase, which incites an inflammatory response. Neutrophil products can further impair the mucosal defenses, favoring the bacteria, but if the infection is overcome, symptoms resolve. However, if the infection persists, chronic inflammation may cause lung damage. About half of exacerbations involve bacterial infection, but these patients are not easy to differentiate from those who are uninfected, which means that antibiotics have to be given more often than is strictly necessary. Further research is needed to characterize those patients in whom bacterial infection has a more important role.

The chemotactic activity of sputum from patients with bronchiectasis

Persistent polymorphonuclear neutrophil (PMN) recruitment to airway is thought to be an important component of continuing inflammation and progression of chronic destructive lung diseases. Although chemoattractants are required for the PMN to migrate, the nature of the chemoattractants in the airways has not yet been clarified. We therefore investigated the contribution of interleukin-8 (IL-8) and leukotriene-B4 (LTB4) to the chemotactic activity of lung secretions by inhibiting their activity using a monoclonal antibody to IL-8 and an LTB4 receptor antagonist (LY293111 sodium). Fifty-nine sputum samples obtained from 19 patients with bronchiectasis were studied. In preliminary studies the chemotactic responses to IL-8 and LTB4 were found to be additive, and we were able to remove their contribution independently with the appropriate antibody and antagonist. The chemotactic activity of the secretions was related to the macroscopic appearance (mucoid, mucopurulent, and purulent), and this appeared to be related to an increase in IL-8 contribution. Chemotactic activity was reduced by antibiotic therapy and again that seemed to relate to a reduction in the IL-8 contribution. The contributions of LTB4 were similar among the three types of sputum in varying clinical states. These data suggest that LTB4 and IL-8 are important chemotactic factors in lung secretions from such patients, although IL-8 appears to play a more important role during acute exacerbations. These results may be useful in determining therapeutic strategies for chronic destructive lung diseases in the future.

Increased VIP-positive nerve fibers in the mucous glands of subjects with chronic bronchitis

The presence and distribution of neuropeptide-containing nerves within bronchial surgical specimens has been investigated in bronchitic (n = 12) and in nonbronchitic subjects (n = 7). Lung tissue, obtained from patients undergoing thoracotomy for limited lung lesions, was processed immediately and analyzed for nerves using the streptavidin-biotin complex peroxidase method with antisera to the neural marker protein gene product 9.5 (PGP 9.5) and the neuropeptides vasoactive intestinal peptide (VIP), substance P (SP), calcitonin-gene related peptide (CGRP). There were no significant differences between the two groups with respect to the density of PGP 9.5-, SP-, or CGRP-positive nerves in both the locations assessed (smooth muscle layer and glands). The density of VIP-positive nerves was significantly higher in the glands of bronchitic than in nonbronchitic subjects. A negative relationship was found between the presence of airway inflammation, as indexed by mononuclear cell tissue infiltration, and the density of PGP 9.5-positive nerves in both smooth muscle and glands. Likewise, a relationship was found between the smoking history (packs/yr and age of onset of smoking) and the density of VIP-positive nerves in glands. These findings support a role for VIP in the hallmark of chronic bronchitis, i.e., sputum production.

Interferon gamma and interleukin 4 stimulate prolonged expression of inducible nitric oxide synthase in human airway epithelium through synthesis of soluble mediators

Human respiratory epithelium expresses inducible nitric oxide synthase (iNOS) continuously in vivo, however mechanisms responsible for maintenance of expression are not known. We show that IFNgamma is sufficient for induction of iNOS in primary human airway epithelial cells (HAEC) in vitro, and IL-4 potentiates IFNgamma-induced iNOS expression in HAEC through stabilization of iNOS mRNA. IFNgamma/IL-4- induced iNOS expression in HAEC was delayed in onset and prolonged with expression up to 1 wk. Removal of overlying culture media resulted in loss of expression, while transfer of conditioned media induced iNOS mRNA in other HAEC. IFNgamma and IL-4 stimulation activated STAT1 and STAT6 in HAEC, but conditioned media transfer to HAEC produced even higher levels of STAT1 activation than achieved by direct addition of cytokines. Although cytokine induction of iNOS was dependent on new protein synthesis, conditioned media induction of iNOS in HAEC was not. Further, removal of overlying culture media from cells at different times after cytokine stimulation demonstrated that mediator synthesis and/or secretion important for induction and maintenance of iNOS occurs early after cytokine stimulation. In conclusion, a combination of IFNgamma/ IL-4, which occurs naturally in the lung epithelial lining fluid, leads to maintenance of iNOS expression in human airway epithelium through production of soluble mediators and stabilization of mRNA.

Peripheral blood lymphocyte cell subsets in subjects with chronic obstructive pulmonary disease: association with smoking, IgE and lung function

In contrast to the numerous studies which show that lymphocytes play an important role in the pathogenesis of asthma, few studies have investigated the role of lymphocytes in the pathogenesis of chronic obstructive pulmonary disease (COPD). The aim of the present study was to investigate lymphocyte subsets in peripheral venous blood of smoking and non-smoking COPD patients and healthy controls. The interaction of smoking and IgE has also been assessed, and it was investigated whether a lower level of FEV1 was associated with changes in lymphocyte subsets. In the present study, peripheral venous blood lymphocyte subsets were investigated in 42 smoking and non-smoking, non-atopic subjects with a clear diagnosis of COPD (43-74 years) who all used bronchodilator therapy only, and in 24 normal, healthy control subjects (40-72 years). No significant differences in lymphocyte subsets were found when either total groups or smoking subjects of both groups were compared. However, the percentage of CD8+ lymphocytes (suppressor/ cytotoxic T-cells) was significantly higher in the non-smoking COPD subjects compared with the non-smoking, healthy control subjects (P < 0.05). In addition, within the group of non-smoking COPD subjects, a higher CD4:CD8 ratio was associated with a higher FEV1 as a percentage of predicted (% pred.) (r = 0.55, P = 0.01) and a lower total serum IgE (r = -0.45, P = 0.04). Within the group of smoking COPD subjects, a higher FEV1 % pred. was associated with a higher percentage of CD19+ lymphocytes (B-cells) (r = 0.65, P < 0.01). The present study provides further evidence that the changes in the balance of T-cell subsets and IgE synthesis possibly plays a role in the pathogenesis of COPD.

Activation of eosinophils and fibroblasts assessed by eosinophil cationic protein and hyaluronan in BAL. Association with acute rejection in lung transplant recipients

Lung transplantation has become an accepted therapy for end-stage lung disease. Acute rejection of the transplanted hung still remains a major clinical problem since it decreases graft survival. Eosinophil cationic protein (ECP) from activated eosinophils, hyaluronan (HYA) from fibroblasts, and circulating intercellular adhesion molecule 1 (1CAM-1) have been associated with acute rejection in kidney and liver grafts. We investigated whether these, as well as other molecules, were increased in acute rejection of lung allografts. Serum and BAL fluid from 38 bronchoscopies performed in 9 single lung, 2 bilateral lung, and 4 heart-lung transplant patients were studied. Differential cell counts were made from the BAL fluid. Levels of ECP, myeloperoxidase (MPO), and HYA were used as indirect markers for activation of eosinophils, neutrophils, and fibroblasts, respectively. In addition, levels of circulating ICAM-1, cVCAM-1, and cE-selectin were analyzed. Twenty-two episodes with acute rejection were diagnosed. Of these, 7 were minimal, 13 were mild, and 2 were of moderate character. We found increased levels of ECP and HYA in BAL fluid during mild acute rejection of the allograft. Numbers of eosinophils were also increased. Activation of neutrophils or neutrophil numbers were not significantly increased. Levels of circulating ICAM-1, cVCAM-1, and cE-selectin did not differ between the groups. This retrospective study shows that measurements of ECP and HYA can give information about the inflammatory process present during acute rejection in patients who have undergone lung transplants. Analysis of cCAMS, however, appears to be of limited value as markers for acute rejection.

Wool and grain dusts stimulate TNF secretion by alveolar macrophages in vitro

OBJECTIVE

The aim of the study was to investigate the ability of two organic dusts, wool and grain, and their soluble leachates to stimulate secretion of tumour necrosis factor (TNF) by rat alveolar macrophages with special reference to the role of lipopolysaccharide (LPS).

METHODS

Rat alveolar macrophages were isolated by bronchoalveolar lavage (BAL) and treated in vitro with whole dust, dust leachates, and a standard LPS preparation. TNF production was measured in supernatants with the L929 cell line bioassay.

RESULTS

Both wool and grain dust samples were capable of stimulating TNF release from rat alveolar macrophages in a dose-dependent manner. The standard LPS preparation caused a dose-dependent secretion of TNF. Leachates prepared from the dusts contained LPS and also caused TNF release but leachable LPS could not account for the TNF release and it was clear that non-LPS leachable activity was present in the grain dust and that wool dust particles themselves were capable of causing release of TNF. The role of LPS in wool dust leachates was further investigated by treating peritoneal macrophages from two strains of mice, LPS responders (C3H) and LPS non-responders (C3H/HEJ), with LPS. The non-responder mouse macrophages produced very low concentrations of TNF in response to the wool dust leachates compared with the responders.

CONCLUSIONS

LPS and other unidentified leachable substances present on the surface of grain dust, and to a lesser extent on wool dust, are a trigger for TNF release by lung macrophages. Wool dust particles themselves stimulate TNF. TNF release from macrophages could contribute to enhancement of inflammatory responses and symptoms of bronchitis and breathlessness in workers exposed to organic dusts such as wool and grain.

Airways obstruction, chronic expectoration, and rapid decline of FEV1 in smokers are associated with increased levels of sputum neutrophils

BACKGROUND

Smoking may cause inflammation of the airways and impairment of lung function. To determine the relationship between the type and degree of airways inflammation and the decline in lung function, leucocytes in the sputum of smokers and ex-smokers were examined.

METHODS

Forty six smokers and ex-smokers of median age 64 years (25%; 75% percentiles 62;66) with a smoking history of 40.1 (31.7;53) pack years were studied with lung function tests and a questionnaire at the end of a 15 year follow up period. Sputum was induced by inhalation of hypertonic saline and differential leucocyte counts were performed on cytospin preparations.

RESULTS

Adequate sputum samples were obtained in 38 subjects (78%). The ratio of forced expiratory volume in one second (FEV1) to vital capacity (VC) was 67.1 (60; 72)% and the annual decline in FEV1 was 19.4 (12;30) ml/year. Subjects with airways obstruction (FEV1/VC < 63%) had more neutrophils (77 (50;86)%) than those without airways obstruction (60 (43;73)%). The percentage of neutrophils was also significantly greater (77 (62;85)%) in those with chronic expectoration than in those without expectoration (57 (45;75)%. Increased levels of neutrophils in the sputum were correlated with a rapid decline in FEV1 over the 15 year follow up period.

CONCLUSIONS

Airways obstruction and chronic expectoration, as well as accelerated decline in lung function, are associated with increased numbers of neutrophils in the sputum of smokers and ex-smokers which suggests that neutrophilic inflammation of the airways may be involved in the pathogenesis of chronic obstructive pulmonary disease.

Different cytokine patterns in bronchial biopsies in asthma and chronic bronchitis

Bronchial biopsies have made possible the detailed study of the pathology of the airways of humans with respiratory disease. Much data has been accumulated on asthmatics or normal controls but much less is known about chronic bronchitics. The aim of this study was to characterize the cellular and cytokine pattern seen in chronic bronchitics and to compare these with control and asthmatic subjects. The patients were also characterized clinically. In this study, immunocytochemistry on cryostat sections from bronchial biopsies were used to determine the level of inflammatory cells and cells of the immune system as well as the pattern of cytokines. This study revealed a distinct cellular and cytokine pattern for each of the three different patient groups, although the diversity of the cytokines analysed was limited by the size of the biopsies. In the inflammatory infiltrate of patients with asthma, CD4+ T-cells and eosinophils were the most prominent cell types discerned. All of the expected cytokines such as IL-1, TNF-alpha, IL-4, IL-5 and IFN-gamma were found. In contrast, the emphasis in chronic bronchitic patients was quite different. The predominant cell types were macrophages, neutrophils, mast cells and CD8+ T-cells, but eosinophils were also abundant. In addition, IL-4 and TNF-alpha were the only cytokines present of those tested.

Immunohistochemical evidence for loss of ICAM-1 by alveolar epithelial cells in pulmonary fibrosis

ICAM-1 is an intercellular adhesion molecule of the immunoglobulin supergene family involved in adherence of leukocytes to the endothelium and in leukocytic accumulation in pulmonary injury. In the current study, the antigen retrieval technique was used to detect ICAM-1 immunohistochemically in paraffin sections of lungs from human, mouse and rat as well as in bleomycin- or radiation-induced fibrotic lungs from rat and human. In normal lung tissue, the expression of ICAM-1 on alveolar type I epithelial cells is stronger than on alveolar macrophages and on endothelial cells. Preembedding immunoelectron microscopy of normal rat, mouse and human lung samples revealed selective ICAM-1 expression on the surface of type I alveolar epithelial cells and, to a lesser extent, on the pulmonary capillary endothelium and on alveolar macrophages. In fibrotic specimens, both focal lack and strengthening of immunostaining on the surface of type I cells was found. Alveolar macrophages were found focally lacking ICAM-1 immunoreactivity. In some cases, rat type II pneumocytes exhibited positive immunoreactions for ICAM-1. Immunoelectron microscopy with preembedded rat lungs (bleomycin-exposed cases) confirmed the altered ICAM-1 distribution at the alveolar epithelial surface. In the alveolar fluid of fibrotic rat lungs, in contrast to that from untreated controls, soluble ICAM-1 was detected by western blot analysis.

Circulating leukocyte adhesion molecules in stable asthma and nonobstructive chronic bronchitis

Leukocyte adhesion molecules have been associated with airway inflammatory diseases such as asthma and obstructive chronic bronchitis. Lately, it has become possible to measure circulating forms of cell adhesion molecules (cCAMs) in body fluids. Elevated serum levels have been found in acute asthma and in obstructive chronic bronchitis. We investigated whether the patterns of cICAM-1, cVCAM-1, and cE-selectin could serve as markers for airway inflammation in stable asthma and stable nonobstructive chronic bronchitis. Small-volume bronchial lavage (BL) and serum from 15 controls, 13 asthmatics without steroid inhalation therapy, 11 asthmatics with regular steroid inhalation therapy, and 10 smokers with chronic bronchitis were analyzed. We found cICAM-1, cVCAM-1, and cE-selectin to be present in serum from patients with stable asthma and stable nonobstructive chronic bronchitis. Only cICAM-1 was found in BL fluid. No differences were seen between the subject groups for either cCAM, but levels of ECP were increased in the non-steroid-treated asthmatic group. Subject atopy or smoking did not increase the cCAM levels. In conclusion, the degree of airway inflammation in stable nonobstructive chronic bronchitis and stable asthma does not appear to be well associated with circulating ICAM-1, cVCAM-1, and cE-selectin.