C. E. Mapp

Airway eosinophilia and expression of interleukin-5 protein in asthma and in exacerbations of chronic bronchitis

Background An increased nutnber of eosinophils in the bronchial mucosa has been demonstrated both in asthma and in exacerbations of chronic bronchitis. Oiyective To investigate whether the airway eosinophilia present in asthma and in chronic bronchitis during exacerbations is associated with interleukin (IL)‐5 protein expression in the bronchial mucosa.

Effect of oxidant air pollutants on the respiratory system: insights from experimental animal research

In the present paper, we have reviewed experimental animal studies on the effects of the two most important oxidant airborne pollutants, nitrogen dioxide and ozone, on the respiratory system. The toxic effects depend on concentration and length of exposure, and are generally similar for both oxidants, with ozone operative at lower concentrations. High doses of both oxidants cause death due to lung oedema. Exposure to sublethal levels causes functional alterations such as airflow limitation and airway hyperresponsiveness to bronchoconstrictor stimuli. These effects, which are generally reversible, are associated with epithelial injury, oedema and airway and parenchymal infiltration by inflammatory cells. Loss of cilia of airway epithelium and necrosis of type I alveolar epithelial cells are the most prominent consequences at the epithelial level. Inflammation is characterized by early neutrophilic infiltration, followed by an increased number of mononuclear cells, predominantly alveolar macrophages. After long-term exposure, whilst nitrogen dioxide causes predominantly emphysema, ozone produces mainly pulmonary fibrosis. Biochemical effects include lipid peroxidation, increased antioxidant metabolism, and alteration of enzyme activity. Nitrogen dioxide and ozone may also alter the immunological response and reduce the defence against infections, increasing the susceptibility of exposed animals to infections.

Sputum eosinophilia after asthmatic responses induced by isocyanates in sensitized subjects

To assess the nature and the time–course of the cellular component of airway inflammation induced by isocyanates, we examined nine subjects with occupational asthma induced by toluene– or methylene diphenyl–diisocyanate (TDI, MDI) and four control subjects never exposed to isocyanates. Sputum was induced by inhalation of ultrasonically nebulized hypertonic saline (3–4% NaCl) before and 8, 24, 48 h after inhalation challenge with TDI or MDI. Expectorated samples were incubated with dithiothreitol, washed and cytocentrifuged. Differential cell counts were obtained on slides stained with May–Grünwald–Giemsa. Metachromatic cells (mast cells and basophils) were counted on slides stained with toluidine blue at pH 0.1. One occupational asthmatic exhibited a dual reaction to TDI, two exhibited a single early asthmatic reaction to M DI, six exhibited a late asthmatic reaction to TDI (n= 5) or M DI (n= 1), whereas no reactions were observed in control subjects after TDI challenge. In sensitized subjects eosinophils increased from a median value (interquartile range) of 5 (15)% before challenge to 29 (29)% (P= 0.014) and to 30 (31)% (P= 0.031) 8 and 24 h after TDI/MDI challenges, respectively. Sputum eosinophilia was observed both in early and late reactors and declined to near to baseline values 48 hr after challenge. Percentages of eosinophils in control subjects did not exceed 7% during the study. There was a significant correlation between the increase in eosinophil counts and the magnitude of the bronchoconstriction expressed as the area of FEV1 response to isocyanate challenge (rank correlation coefficient = 0–71, P= 0.014). No significant changes in sputum neutrophils, macrophages, lymphocytes and mast cells were detected. The results indicate that isocyanate–induced asthmatic responses are associated with influx of eosinophils in airway secretion lasting up to 24 h.

Mechanisms and pathology of occupational asthma

Since the pathogenesis and the pathological features of occupational asthma are similar to those of nonoccupational asthma, the former represents a very useful model for the investigation of the pathogenesis of asthma in general. More than one mechanism may be operative in occupational asthma. Among the mechanisms proposed, immunological mechanisms and airway inflammation play an important role. There is evidence to confirm that T-lymphocyte activation and local accumulation in the bronchial wall of activated eosinophils occurs in asthma of diverse aetiology, i.e. immunoglobulin E (IgE)-mediated, occupational and intrinsic. Neurogenic pathways should be further investigated as a potential mechanism of modulation and amplification of airway inflammation in occupational asthma.

Expression of interleukin (IL)-4 and IL-5 proteins in asthma induced by toluene diisocyanate (TDI).

Background TDI‐induced asthma exhibits clinical, functional and morphological similarities with allergen‐induced asthma, suggesting that an immunological mechanism is involved in the sensitization to TDL In vitro studies using the technique of cloning lymphocytes demonstrated that a great proportion of T‐cell clones derived from bronchial mucosa of subjects with TDI‐induced asthma produced IL‐5 and interferon‐gamma, but not IL‐4, upon in vitro stimulation.

Long-term follow-up of toluene diisocyanate-induced asthma

Eighty-seven cases of occupational asthma induced by toluene diisocyanate (TDI) were diagnosed by an inhalation challenge with TDI and methacholine. After an average follow-up interval of 11 yrs, all subjects were re-examined. Of the 87 subjects examined, 13 (15%) had remained in the same job, 44 (50.5%) had been removed from exposure for <10 yrs and 30 (34.5%) had been removed for >10 yrs. The proportion of subjects who experienced symptoms of asthma and those who were hyperresponsive to methacholine was significantly lower. Of the patients, 59% used short-acting bronchodilators, 8% long-acting bronchodilators and 18% were on regular inhaled glucocorticoids. Thus, multiple regression analysis showed a positive correlation between forced vital capacity (FVC) and forced expiratory volume in one second (FEV1) at follow-up and FVC and FEV1 at diagnosis, and a negative correlation with smoking and with therapy with bronchodilators. Stepwise logistic regression showed that the follow-up provocative dose causing a 20% fall in the FEV1 (PD20) could be predicted from baseline PD20. These results indicate that respiratory symptoms and airway hyperresponsiveness to methacholine persist in subjects removed from exposure to TDI for >10 yrs. A more favourable prognosis was associated with a better lung function and a lower degree of airway hyperresponsiveness to methacholine at diagnosis.

Interleukin‐13 and ‐4 expression in the central airways of smokers with chronic bronchitis

The aim of this study was to determine whether the T‐helper 2‐type cytokines interleukin (IL)‐13 and ‐4 are involved in mucus hypersecretion, the hallmark of chronic bronchitis (CB). Surgical specimens were examined from 33 subjects undergoing lung resection for localised peripheral malignant pulmonary lesions: 21 smokers with symptoms of CB, 10 asymptomatic smokers (AS) and two nonsmokers with normal lung function. The number of IL‐4 and ‐13 positive (+) cells in the central airways was quantified. To better assess the cytokine profile, a count was also made of IL‐5+ and interferon (IFN)‐γ+ cells. Compared to AS, the CB group had an increased number of IL‐13+ and ‐4+ cells in the bronchial submucosa, while the number of IL‐5+ and IFN‐γ+ cells were similar in all the groups. No significant associations were found between the number of cells expressing IL‐13 or ‐4 and the number of inflammatory cells. Double labelling showed that 13.2 and 12.9% of IL‐13+ cells were also CD8+ and CD4+, whereas 7.5 and 5% of IL‐4+ cells were CD8+ and CD4+, respectively. In conclusion, T‐helper‐2 and ‐1 protein expression is present in the central airways of smokers and interleukin‐4 and ‐13 could contribute to mucus hypersecretion in chronic bronchitis.

Expression of protease activated receptor-2 (PAR-2) in central airways of smokers and non-smokers.

Background: Protease activated receptor-2 (PAR-2) is a transmembrane G protein coupled receptor preferentially activated by trypsin and tryptase. The protease activated receptors play an important role in most components of injury responses including cell proliferation, migration, matrix remodelling, and inflammation. Cigarette smoking causes an inflammatory process in the central airways, peripheral airways, lung parenchyma, and adventitia of pulmonary arteries. Methods: To quantify the expression of PAR-2 in the central airways of smokers and non-smokers, surgical specimens obtained from 30 subjects undergoing lung resection for localised pulmonary lesions (24 with a history of cigarette smoking and six non-smoking control subjects) were examined. Central airways were immunostained with an antiserum specific for PAR-2 and PAR-2 expression was quantified using light microscopy and image analysis. Results: PAR-2 expression was found in bronchial smooth muscle, epithelium, glands, and in the endothelium and smooth muscle of bronchial vessels. PAR-2 expression was similar in the central airways of smokers and non-smokers. When smokers were divided according to the presence of symptoms of chronic bronchitis and chronic airflow limitation, PAR-2 expression was increased in smooth muscle (median 3.8 (interquartile range 2.9–5.8) and 1.4 (1.07–3.4) respectively); glands (33.3 (18.2–43.8) and 16.2 (11.5–22.2), respectively); and bronchial vessels (54.2 (48.7–56.8) and 40.0 (36–40.4), respectively) of smokers with symptoms of chronic bronchitis with normal lung function compared with smokers with chronic airflow limitation (COPD), but the increase was statistically significant (p<0.005) only for bronchial vessels. Conclusions: PAR-2 is present in bronchial smooth muscle, glands, and bronchial vessels of both smokers and non-smokers. An increased expression of PAR-2 was found in bronchial vessels of patients with bronchitis compared with those with COPD.

Macrophage expression of interleukin-10 is a prognostic factor in nonsmall cell lung cancer.

Interleukin (IL)-10 is expressed in many solid tumours and plays an ambiguous role in controlling cancer growth and metastasis. In order to determine whether IL-10 is involved in tumour progression and prognosis in nonsmall cell lung cancer (NSCLC), IL-10 expression in tumour cells and tumour-associated macrophages (TAMs) and its associations, if any, with clinicopathological features were investigated. Paraffin-embedded sections of surgical specimens obtained from 50 patients who had undergone surgery for NSCLC were immunostained with an antibody directed against IL-10. TAMs and tumour cells positive for IL-10 were subsequently quantified. IL-10-positive TAM percentage was higher in patients with stage II, III and IV NSCLC, and in those with lymph node metastases compared with patients with stage I NSCLC. High IL-10 expression by TAMs was a significant independent predictor of advanced tumour stage, and thus was associated with worse overall survival. Conversely, IL-10 expression by tumour cells did not differ between stages II, III and IV and stage I NSCLC. In conclusion, interleukin-10 expression by tumour-associated macrophages, but not by tumour cells, may play a role in the progression and prognosis of nonsmall cell lung cancer. These results may be useful in the development of novel approaches for anticancer treatments.

Association between toluene diisocyanate-induced asthma and DQB1 markers: a possible role for aspartic acid at position 57

Toluene diisocyanate (TDI) is the most common cause of occupational asthma in western countries. The aim of this study was to investigate whether genetic factors are involved in toluene diisocyanate-induced asthma. We studied the frequency of human leucocyte antigen (HLA) class II genetic markers in three groups of subjects: 1) subjects with TDI-induced asthma (n = 30); 2) exposed subjects with no history of TDI-induced asthma (n = 12); and 3) normal subjects not exposed to TDI (n = 126). Venous blood samples were collected from the three groups and the polymorphic second exon of DQA and DQB genes was amplified by the polymerase chain reaction (PCR) method. Evaluation of HLA class II gene products in TDI-induced asthma cases showed a positive association with HLA-DQB1 * 0503 and a negative association with HLA-DQB1 * 0501 alleles, which differed at residue 57 for a single amino acid, i.e. aspartic acid in DQB1 * 0503 and valine in DQB1 * 0501. No significant difference was found in the distribution of DQA1 alleles between asthmatics and controls. Our results confirm the hypothesis that HLA-DQB1 * 0503 has a role in conferring susceptibility to TDI-induced asthma and that residue 57 of HLA-DQB1 is a potentially critical location.