Airway Mucosal Inflammation in Occupational Asthma Induced by Toluene Diisocyanate 1- 4
MARINA SAETTA, A. 01 STEFANO, P. MAESTRELLI, NICOLETTA DE MARZO, G. F. MILANI, F. PIVIROTTO, CRISTINA E. MAPP, and L. M. FABBRI Introduction
Descriptions of the pathologic features of bronchial asthma are largely based on autopsy studies (1, 2) and, more recently, on studies of bronchoalveolar lavage (3, 4) and bronchial biopsies (5-8). These studies have been mainly performed in patients with allergic asthma and have established that epithelial shedding, subepithelial collagen thickening, and airway mucosal inflammation are characteristic features of this type of asthma. Only a few studies are available on the pathology of occupational asthma induced by toluene diisocyanate (TDI). Severe airway inflammation was described in a worker with asthma induced by TDI who died after an acute occupational exposure to polyurethane paint (9). However, it is unclear to what extent these postmortem findings reflect the actual pathology of occupational asthma. It has been shown that, in sensitized subjects, acute exposure to TDI (10) is able to induce airway inflammation as detected by bronchoalveolar lavage, but bronchoalveolar lavage findings may not reflect the pathology of airway mucosa (11). The only study on bronchial biopsies in patients with TDI-induced asthma showed mild inflammatory infiltrate after cessation of exposure (12). However, in that study, the pathology was not quantified, and, as far as we know, no quantitative analysis of bronchial biopsies from subjects with occupational asthma, particularly with TDI-induced asthma, has been reported thus far. To determine the nature and the degree of airway mucosal inflammation in TDI asthma, we performed a quantitative analysis of bronchial biopsies obtained from patients with occupational asthma induced by TDI and from nonasthmatic subjects who had never been exposed to TDI. Methods Subjects Nine patients with occupational asthma induced by TDI confirmed by a positive specif160
SUMMARY We examined the light and electron microscopic structure of lobar bronchial biopsies of nine subjects with occupational asthma induced by toluene dllsocyanate (TOI) and of four control nonasthmatlc subjects who had never been exposed to TOI.lnflammatory cell numbers wereseparately assessed In the Intact epithelium, in the more superficial layer of the submucosa, and In the total submucosa. Asthmatic subjects had an increased number of Inflammatory cells in the airway mucosa compared with control SUbJects. Eoslnophlls were significantly increased In all compartments, C045-positive cells were significantly Increased In the epithelium and In the more superficial layer of the submucosa, and mast cells were significantly Increased only In the epithelium. Byelectron microscopy eoslnophlls and mast cells appeared degranulated only In asthmatic patients. In the areas of epithelium that appeared Intact by light microscopy, electron microscopy showed that, although the Intercellular spaces between columnar cells weresimilar In asthmatic and control groups, the intercellular spaces between basal cells were significantly wider In patients with asthma. Patients with TOI·induced asthma also had a thicker subepithelial reticular layer, where Immunohistochemistry showed the presence of collagen III. In conclusion, In patients with asthma Induced by TOI, the airway mucosa shows pathologic features, such as Inflammatory cell Infiltrate and thickening of subepithelial collagen, similar to those described in atopic asthma. AM REV RESPIR DIS 1992; 145:160-168
ic inhalation challenge (13)and four nonasthmatic control subjects were included in the study. Control subjects had no past history of asthma and of exposure to isocyanates, a baseline FEV 1 greater than 80070 of predicted, and provocative dose (PD 2 0 ) FEV 1 methacholine greater than 1.4 mg. Eight of the nine asthmatic subjects were treated in the past with only intermittent inhaled bronchodilator therapy, and one patient was taking inhaled steroid therapy irregularly. All asthmatic and control subjects were nonsmokers and had been free of clinical, symptomatic respiratory infections for at least 8 wk. They had not received oral or inhaled corticosteroids within the preceding month, nor had they received sympathomimetics, antihistamines, theophylline, anticholinergics, or cromolyn within 24 h of the study. Asthmatic patients were exposed to TDI at work until 4 to 6 days before the specific inhalation challenge with TDI. The characteristics of the subjects are reported in table 1. The study conformed to the Declaration of Helsinki, and informed written consent was obtained from each subject. Each patient underwent interview, chest X-ray, ECG, routine blood tests, skin tests with common allergen extracts, lung function measurements, inhalation challenge with methacholine (14), and specific inhalation challenge with TDI (13) 1 to 2 wk before bronchoscopy. During this interval the patients were not occupationally exposed to TDI. Control subjects did not undergo specific inhalation challenge with TDI.
Bronchoscopy All subjects were premedicated intravenously with atropine (0.5 to 1 mg), fentanyl (0.15 to 0.30 mg), and droperidol (5 to 10mg). Nares and oropharynx were anesthetized topically with 2% lidocaine before bronchoscopy. Bronchoscopy was performed with a ventilation rigid bronchoscope (K. Storz GMBH, Tuttligen, Germany) in seven asthmatic subjects and in one control subject, and with a flexible fiberoptic bronchoscope (Olympus BF, type IT 10; Olympus Co., Tokyo, Japan) in the remaining two asthmatic and three control subjects. The instrument was introduced transorally or transnasally and passed through (Received in original form November 26, 1990and in revised form April 25, 1991) 1 From the Institute of Occupational Medicine, University of Padova, Padova, and the Department of Pneumology, Rovigo General Hospital, Rovigo, Italy. 2 Presented at the Societas Europaea Pneumologica-Societas Europaea Physiologiae Clinicae Respiratoriae Joint Meeting, London, September 9-14, 1990. 3 Supported by Italian National ResearchCouncil Grants Nos. 89.04247.04, 89.04159.04, and 90.02443.CT04, the Italian Ministry of Education, the Regione Veneto, and the European Community for Coal and Steel. 4 Correspondence and requests for reprints should be addressed to Marina Saetta, M. D., Institute of Occupational Medicine, University of Padova, Via Facciolati 71, 35127 Padova, Italy.
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the larynx. Up to 10ml of 2070 lidocaine were instilled through the bronchoscope into the trachea and bronchi. Bronchial biopsies were taken through the bronchoscope with standard forceps (optical biopsy forceps for rigid bronchoscope [K. Storz GMBH, Tiibingen, Germany] and FB 15C forceps for flexible bronchoscope [Olympus Co., Tokyo, Japan]) at two different levels of the airways in each subject: (1) from the subcarina of a basal segment bronchus of the right lower lobe (Samples a and b); and (2) from the subcarina of the right upper lobe (Sample c). Sample Processing and Analysis Biopsies were gently extracted from the forceps and immediately fixed for light (sample a) and electron microscopy (Sample c). Sample b was embedded in Tissue Tek
MARINA SAETTA, A. 01 STEFANO, P. MAESTRELLI, NICOLETTA DE MARZO, G. F. MILANI, F. PIVIROTTO, CRISTINA E. MAPP, and L. M. FABBRI Introduction
Descriptions of the pathologic features of bronchial asthma are largely based on autopsy studies (1, 2) and, more recently, on studies of bronchoalveolar lavage (3, 4) and bronchial biopsies (5-8). These studies have been mainly performed in patients with allergic asthma and have established that epithelial shedding, subepithelial collagen thickening, and airway mucosal inflammation are characteristic features of this type of asthma. Only a few studies are available on the pathology of occupational asthma induced by toluene diisocyanate (TDI). Severe airway inflammation was described in a worker with asthma induced by TDI who died after an acute occupational exposure to polyurethane paint (9). However, it is unclear to what extent these postmortem findings reflect the actual pathology of occupational asthma. It has been shown that, in sensitized subjects, acute exposure to TDI (10) is able to induce airway inflammation as detected by bronchoalveolar lavage, but bronchoalveolar lavage findings may not reflect the pathology of airway mucosa (11). The only study on bronchial biopsies in patients with TDI-induced asthma showed mild inflammatory infiltrate after cessation of exposure (12). However, in that study, the pathology was not quantified, and, as far as we know, no quantitative analysis of bronchial biopsies from subjects with occupational asthma, particularly with TDI-induced asthma, has been reported thus far. To determine the nature and the degree of airway mucosal inflammation in TDI asthma, we performed a quantitative analysis of bronchial biopsies obtained from patients with occupational asthma induced by TDI and from nonasthmatic subjects who had never been exposed to TDI. Methods Subjects Nine patients with occupational asthma induced by TDI confirmed by a positive specif160
SUMMARY We examined the light and electron microscopic structure of lobar bronchial biopsies of nine subjects with occupational asthma induced by toluene dllsocyanate (TOI) and of four control nonasthmatlc subjects who had never been exposed to TOI.lnflammatory cell numbers wereseparately assessed In the Intact epithelium, in the more superficial layer of the submucosa, and In the total submucosa. Asthmatic subjects had an increased number of Inflammatory cells in the airway mucosa compared with control SUbJects. Eoslnophlls were significantly increased In all compartments, C045-positive cells were significantly Increased In the epithelium and In the more superficial layer of the submucosa, and mast cells were significantly Increased only In the epithelium. Byelectron microscopy eoslnophlls and mast cells appeared degranulated only In asthmatic patients. In the areas of epithelium that appeared Intact by light microscopy, electron microscopy showed that, although the Intercellular spaces between columnar cells weresimilar In asthmatic and control groups, the intercellular spaces between basal cells were significantly wider In patients with asthma. Patients with TOI·induced asthma also had a thicker subepithelial reticular layer, where Immunohistochemistry showed the presence of collagen III. In conclusion, In patients with asthma Induced by TOI, the airway mucosa shows pathologic features, such as Inflammatory cell Infiltrate and thickening of subepithelial collagen, similar to those described in atopic asthma. AM REV RESPIR DIS 1992; 145:160-168
ic inhalation challenge (13)and four nonasthmatic control subjects were included in the study. Control subjects had no past history of asthma and of exposure to isocyanates, a baseline FEV 1 greater than 80070 of predicted, and provocative dose (PD 2 0 ) FEV 1 methacholine greater than 1.4 mg. Eight of the nine asthmatic subjects were treated in the past with only intermittent inhaled bronchodilator therapy, and one patient was taking inhaled steroid therapy irregularly. All asthmatic and control subjects were nonsmokers and had been free of clinical, symptomatic respiratory infections for at least 8 wk. They had not received oral or inhaled corticosteroids within the preceding month, nor had they received sympathomimetics, antihistamines, theophylline, anticholinergics, or cromolyn within 24 h of the study. Asthmatic patients were exposed to TDI at work until 4 to 6 days before the specific inhalation challenge with TDI. The characteristics of the subjects are reported in table 1. The study conformed to the Declaration of Helsinki, and informed written consent was obtained from each subject. Each patient underwent interview, chest X-ray, ECG, routine blood tests, skin tests with common allergen extracts, lung function measurements, inhalation challenge with methacholine (14), and specific inhalation challenge with TDI (13) 1 to 2 wk before bronchoscopy. During this interval the patients were not occupationally exposed to TDI. Control subjects did not undergo specific inhalation challenge with TDI.
Bronchoscopy All subjects were premedicated intravenously with atropine (0.5 to 1 mg), fentanyl (0.15 to 0.30 mg), and droperidol (5 to 10mg). Nares and oropharynx were anesthetized topically with 2% lidocaine before bronchoscopy. Bronchoscopy was performed with a ventilation rigid bronchoscope (K. Storz GMBH, Tuttligen, Germany) in seven asthmatic subjects and in one control subject, and with a flexible fiberoptic bronchoscope (Olympus BF, type IT 10; Olympus Co., Tokyo, Japan) in the remaining two asthmatic and three control subjects. The instrument was introduced transorally or transnasally and passed through (Received in original form November 26, 1990and in revised form April 25, 1991) 1 From the Institute of Occupational Medicine, University of Padova, Padova, and the Department of Pneumology, Rovigo General Hospital, Rovigo, Italy. 2 Presented at the Societas Europaea Pneumologica-Societas Europaea Physiologiae Clinicae Respiratoriae Joint Meeting, London, September 9-14, 1990. 3 Supported by Italian National ResearchCouncil Grants Nos. 89.04247.04, 89.04159.04, and 90.02443.CT04, the Italian Ministry of Education, the Regione Veneto, and the European Community for Coal and Steel. 4 Correspondence and requests for reprints should be addressed to Marina Saetta, M. D., Institute of Occupational Medicine, University of Padova, Via Facciolati 71, 35127 Padova, Italy.
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PATHOLOGY OF OCCUPATIONAL ASTHMA
the larynx. Up to 10ml of 2070 lidocaine were instilled through the bronchoscope into the trachea and bronchi. Bronchial biopsies were taken through the bronchoscope with standard forceps (optical biopsy forceps for rigid bronchoscope [K. Storz GMBH, Tiibingen, Germany] and FB 15C forceps for flexible bronchoscope [Olympus Co., Tokyo, Japan]) at two different levels of the airways in each subject: (1) from the subcarina of a basal segment bronchus of the right lower lobe (Samples a and b); and (2) from the subcarina of the right upper lobe (Sample c). Sample Processing and Analysis Biopsies were gently extracted from the forceps and immediately fixed for light (sample a) and electron microscopy (Sample c). Sample b was embedded in Tissue Tek
