Fatal asthma attack during an inhalation challenge with ultrasonically nebulized distilled water.
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Adult↗
Biomedical subjects
M Saetta
Publications and source records attributed to M Saetta.
Airway wall remodeling after cessation of exposure to isocyanates in sensitized asthmatic subjects.
To determine whether the cessation of exposure to isocyanates is associated with structural changes of the airway wall in sensitized subjects, we studied bronchial biopsies from 10 subjects with occupational asthma induced by toluene diisocyanate (TDI). Bronchial challenges with TDI and methacholine were performed and biopsies were taken on two occasions, at diagnosis and 6 to 21 mo after cessation of exposure to TDI. After bronchoscopy, biopsies were formalin-fixed or snap-frozen in liquid nitrogen and then processed for a quantitative histochemical and immunohistochemical analysis. After cessation of exposure, we observed a significant decrease of the sensitivity to TDI (p < 0.05), of the thickness of subepithelial fibrosis (p < 0.007), and of the numbers of subepithelial fibroblasts (p < 0.05), mast cells (p < 0.02), and lymphocytes (p < 0.03) as compared with values at diagnosis. By contrast, the nonspecific bronchial hyperresponsiveness and the numbers of macrophages and eosinophils did not change. In conclusion, in patients with occupational asthma induced by TDI, the cessation of exposure to the sensitizing agent is associated with a reduced thickness of subepithelial fibrosis and with a reduced number of subepithelial fibroblasts, mast cells, and lymphocytes in the bronchial mucosa, suggesting a remodeling of the airway wall with the avoidance of the specific stimulus.
Adolescent↗
Cytokines in the airway mucosa of subjects with asthma induced by toluene diisocyanate.
To determine the status of activation of lymphocytes and the role of cytokines on the inflammatory response of the bronchial mucosa in toluene diisocyanate (TDI) asthma, we performed a quantitative analysis of bronchial biopsies obtained from 15 subjects with TDI-induced asthma and seven normal control subjects. Markers of activation of lymphocytes (CD25 and Very Late activation Antigen-1, VLA-1) and expression of Tumor Necrosis Factor-alpha (TNF alpha) and interleukin-1 beta (IL-1 beta) were determined by immunohistology in the submucosa. Moreover, expression of adhesion molecules on endothelium of submucosal vessels was assessed. Asthmatic subjects had increased numbers of cells expressing CD25 and VLA-1 compared with the control group (p < 0.05). TNF alpha and IL-1 beta immunoreactivity was increased in asthmatics compared with control subjects (p < 0.01), whereas the expression of adhesion molecules, ICAM-1 and E-selectin, on vascular endothelium was not significantly different. No significant differences in the morphologic quantifications were observed between the asthmatics who had biopsies taken 2 d after TDI challenge (n = 7) and those with longer interval (21 +/- 8 d) between TDI challenge and biopsy (n = 8), suggesting that the increase in CD25, VLA-1, TNF alpha, and IL-1 beta was not due to an acute effect, but could be considered a part of the chronic inflammatory process of the airways. We conclude that the inflammatory response of the airways in TDI-induced asthma is characterized by persistent activation of lymphocytes and by chronic expression of proinflammatory cytokines.
Adult↗
Effect of smoking cessation on airway inflammation in chronic bronchitis.
To investigate the effect of smoking cessation on the airway inflammatory process present in nonatopic subjects with chronic bronchitis, we obtained bronchial biopsies from nine current smokers and seven exsmokers, all with symptoms of chronic bronchitis at the time of the study, and from seven healthy nonsmoking subjects. The exsmokers had stopped smoking on average 13 yr before the study, yet cough and production of sputum had persisted. Bronchial biopsies were assessed using immunohistochemical techniques to investigate the number of inflammatory cells, the markers of mononuclear cell activation, and the expression of endothelial adhesion molecules and cytokines in the subepithelium. Current smokers and exsmokers had an increased number of macrophages, IL-2R-positive cells, VLA-1-positive cells, ICAM-1-positive vessels, and E-selectin-positive vessels compared with normal nonsmoking subjects, but the number of cells positive for neutrophils, EG-2, CD3, CD4, CD8, TNF-alpha and IL-1 beta were similar among the three groups. No differences were observed between current smokers and exsmokers for any parameter examined. In conclusion, the inflammatory process present in the airway mucosa of current smokers may persist after smoking cessation in subjects who continue to have symptoms of chronic bronchitis.
Aged↗
Comparison of leukocyte counts in sputum, bronchial biopsies, and bronchoalveolar lavage.
To determine the relationship between inflammatory cells in sputum, bronchoalveolar lavage (BAL), and bronchial mucosa, we counted the number of leukocytes in sputum, BAL, and bronchial biopsies obtained from subjects with asthma and with chronic bronchitis in stable condition or during exacerbations. Sputum was induced by inhalation of hypertonic saline in the asthma group. Spontaneous sputum was collected in the chronic bronchitis groups. Differential counts of leukocytes were performed on cytospin preparations of sputum and BAL. Eosinophils, macrophages, neutrophils, and lymphocytes were quantified in the submucosa of the bronchial biopsies. In asthma and in stable chronic bronchitis, the percentages of neutrophils were significantly higher in sputum than in BAL, whereas the opposite was true of the percentages of macrophages and lymphocytes. The lymphocyte was the predominant cell infiltrating the bronchial submucosa in all groups. BAL eosinophils correlated with submucosal and sputum eosinophils in the asthma and exacerbated chronic bronchitis groups. A similar trend was observed between submucosal and sputum eosinophils. In conclusion, the relative proportion of inflammatory cells was different in sputum, BAL, and bronchial mucosa. However, there was a fairly good agreement between the number of eosinophils counted with the three techniques in asthmatics and in exacerbated chronic bronchitics, suggesting that sputum cell analysis may be used for a noninvasive assessment of airway eosinophilia.
Adult↗
The effects of toluene diisocyanate and of capsaicin on human bronchial smooth muscle in vitro.
Toluene diisocyanate contracts guinea-pig bronchial smooth muscle through a mechanism involving capsaicin-sensitive sensory nerves. In the present study, we investigated the effects of toluene diisocyanate, capsaicin and tachykinins on isolated human bronchi. In 44 rings, toluene diisocyanate (0.3 mM) produced a relaxation which averaged 16.9 +/- 1.1%, in ten rings it produced a shortening that was 15.1 +/- 3.3% and in ten preparations it gave no response. A second administration of toluene diisocyanate (0.3 mM) always produced a relaxation (n = 13, 18.1 +/- 3.9%). Capsaicin (0.03 mM) produced shortening in 15 (35 +/- 6.6%) and relaxation in 11 preparations (41 +/- 6.8%), whereas a second administration caused shortening in nine (25.1 +/- 6.1%) and relaxation in 16 rings (36.4 +/- 4.9%). When toluene diisocyanate was given after two consecutive capsaicin administrations, we observed shortening in two rings (10.0 +/- 3.6%), relaxation in ten rings (15.9 +/- 3.6%), and no response in four preparations. To test the role of NK1 and NK2 receptors in these conflicting responses, we performed concentration-response curves to different tachykinins. Substance P, neurokinin A and neurokinin A-(4-10), a specific NK2 receptor agonist, gave a concentration-dependent shortening, with neurokinin A being the most effective and neurokinin A-(4-10) the least. The specific NK1 receptor agonist, [Sar9, Met(O2)11]substance P, produced both shortening and relaxation. We conclude that toluene diisocyanate and capsaicin may produce both shortening and relaxation in isolated human bronchi through NK1 receptors.
Acetylcholine↗
In vitro exposure to nitrogen dioxide (NO2) does not alter bronchial smooth muscle responsiveness in ovalbumin-sensitized guinea-pigs.
The aim of this study was to investigate whether in vitro exposure to NO2 affects responsiveness in ovalbumin-sensitized guinea-pig bronchi. Twenty-three animals were sensitized by three weekly intraperitoneal injections of 1 mg ovalbumin in saline with Freund's adjuvant; twenty-one control guinea-pigs received the diluent alone. From each animal, the two main bronchi were obtained and cannulated, then exposed in vitro to a constant intraluminal flow of: (i) either air or 2.5 ppm NO2 with four spikes of 10 ppm NO2 for 2 h; (ii) either air or 10 ppm NO2 for 4 h. A bronchial ring obtained from each animal before exposure was kept in aerated Krebs-Henseleit solution. Rings from bronchi exposed to air, NO2, or kept in Krebs solution were studied isometrically. We performed overall and non-adrenergic non-cholinergic voltage-response curves to electrical field stimulation, concentration-response curves to acetylcholine and to neurokinin A, followed by administration of 10 mg/ml ovalbumin. We did not find any significant difference in bronchial smooth muscle responsiveness between nonexposed, air-exposed and NO2-exposed bronchi, as well as between bronchi from control and sensitized animals. We conclude that in vitro exposure to NO2 does not alter bronchial smooth muscle responsiveness to either specific or non-specific stimuli.
Acetylcholine↗
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 MDI, six exhibited a late asthmatic reaction to TDI (n = 5) or MDI (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.(ABSTRACT TRUNCATED AT 250 WORDS)
Adult↗
Mechanisms of occupational asthma.
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Allergens↗
Eosinophil cationic protein (ECP), histamine and tryptase in peripheral blood before and during inhalation challenge with toluene diisocyanate (TDI) in sensitized subjects.
To determine whether the measurement of specific markers of inflammatory cells in peripheral blood might be used to detect the inflammatory activity in the airways in asthma induced by toluene diisocyanate (TDI), we measured the levels of eosinophil cationic protein (ECP), histamine and tryptase in peripheral blood before and during inhalation challenge with TDI or methacholine in two groups of subjects who exhibited or did not exhibit an asthmatic reaction after exposure to toluene diisocyanate in the laboratory. When the subjects developed a late asthmatic reaction after exposure to TDI, they showed an increase in their ECP serum levels. By contrast, there were no significant changes in serum ECP levels after exposure to TDI in the control group or after methacholine challenge in either group. Tryptase levels in serum were not detectable before or during inhalation challenge with TDI or methacholine. There was no significant increase in plasma histamine levels during inhalation challenge with TDI or methacholine. These results suggest that eosinophils are 'activated' in subjects who develop a late asthmatic reaction after exposure to TDI and that the measurement of ECP levels in peripheral blood may be a useful marker to monitor airway inflammation.
Administration, Inhalation↗
Upregulation of adhesion molecules in the bronchial mucosa of subjects with chronic obstructive bronchitis.
To determine whether adhesion molecules and cytokines are upregulated in the bronchial mucosa of chronic bronchitics, we obtained bronchial biopsies in 16 chronic bronchitics, in eight asymptomatic smokers, and in seven normal nonsmoking subjects. Bronchial biopsies were examined by immunohistochemistry to identify the expression of E-selectin and intercellular adhesion molecular-1 (ICAM-1) on vessels and on bronchial epithelium, and the expression of interleukin-1 beta (IL-1 beta), tumor necrosis factor-alpha (TNF-alpha), neutrophil elastase, and eosinophil cationic protein (EG-2) on cells in the submucosa. Chronic bronchitics had an increased number of E-selectin-positive vessels when compared with both asymptomatic smokers (p < 0.05) and normal subjects (p < 0.01). The numbers of ICAM-1-positive vessels, neutrophils, and IL-1 beta, TNF-alpha-, and EG-2-positive cells were not significantly different in the three groups of subjects examined. When the bronchitic group was divided according to the presence or absence of airway obstruction, the increased number of E-selectin-positive vessels persisted only in bronchitics with airway obstruction, who also had an increased expression of ICAM-1 on basal epithelial cells. We concluded that in the bronchial mucosa of chronic bronchitics with airway obstruction, there is an increased expression of E-selectin on vessels and of ICAM-1 on basal epithelial cells, suggesting the involvement of these adhesion molecules in the pathogenesis of the disease.
Adult↗
Predictive value of airways hyperresponsiveness and circulating IgE for identifying types of responses to toluene diisocyanate inhalation challenge.
Development of asthma after exposure to toluene diisocyanate (TDI) has been recognized in a variety of occupational settings. However, the pathogenesis of isocyanate-induced asthma remains controversial. In particular, the role of IgE in the development of TDI-induced asthma has remained uncertain. To investigate predictive factors for response to inhalation challenge with TDI, we analyzed data from 63 subjects referred for evaluation of respiratory symptoms thought to be related to TDI sensitization. All subjects underwent interview, routine phlebotomy, spirometry, methacholine challenge, and allergy skin testing prior to TDI challenge. Spirometry and methacholine challenge were repeated 1 day after TDI challenge. The cumulative dose of methacholine needed to produce a 20% decrease in FEV1 (PD20) was determined. A PD20 of 1.4 mg or more was considered normal. Subjects were challenged by exposure to 5 to 10 ppb TDI for up to 30 min in a 9 m3 exposure chamber. A positive response was a 20% or more decrease in FEV1 within 1 h (early) or beyond 1 h (late) after TDI exposure. Thirty-four subjects (54%) had a positive response, of whom 12 (35% of responders) had isolated early responses, 13 (38%) had isolated late responses, and the remainder had dual responses. Thirty-two individuals (51%) had a positive response to methacholine (AR+) prior to TDI challenge. AR+ was strongly associated with a positive TDI challenge: 23 AR+ subjects (72%) had a positive TDI challenge, compared with only 11 AR- subjects (35%) (p < 0.01). AR positivity did not predict the time of onset of TDI response.(ABSTRACT TRUNCATED AT 250 WORDS)
Adult↗
Airway eosinophilia in chronic bronchitis during exacerbations.
To examine the nature and the degree of airway inflammation in chronic bronchitis during exacerbations, bronchial biopsies and sputum were obtained in 11 subjects with chronic bronchitis examined during an exacerbation, and in 12 subjects with chronic bronchitis examined under baseline conditions. All subjects were nonatopic. Lobar bronchial biopsies were assessed using histochemical and immunohistochemical techniques, and sputum was examined for differential cell counts of leukocytes. Subjects with bronchitis during exacerbations had, on average, 30-fold more eosinophils in their bronchial biopsies than did those examined under baseline conditions (p < 0.001). Although to a lesser extent, the numbers of neutrophils (p < 0.01), T-lymphocytes (CD3) (p < 0.05), VLA-1-positive cells (p < 0.01), and TNF-alpha positive cells (p < 0.05) were also increased during exacerbations. By contrast, the T-lymphocyte subpopulations (CD4 and CD8) and the numbers of macrophages, mast cells, IL-2R-positive cells, and IL-1 beta-positive cells were similar in the two groups of subjects, as well as the percentages of ICAM-1- and E-selectin-positive vessels. Eosinophils were also increased in sputum of subjects with exacerbations when compared with those examined under baseline conditions (p < 0.05). In conclusion, exacerbations of chronic bronchitis are associated with a marked airway eosinophilia and with a milder increase in the number of neutrophils, activated T-lymphocytes, and TNF-alpha-positive cells in the bronchial mucosa.
Aged↗
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.
Adult↗
Extent of centrilobular and panacinar emphysema in smokers' lungs: pathological and mechanical implications.
In order to quantify the extent of centrilobular (CLE) and panacinar (PLE) emphysema and the degree of the possible overlap between the two forms in smokers, the lungs of 25 smokers undergoing lung resection for peripheral lung tumours were studied. The extent of CLE and PLE was assessed by point counting, and the lungs were classified as having pure CLE (C, n = 5), predominant CLE with areas of PLE (CP, n = 7), predominant PLE with features of CLE (PC, n = 7), and pure PLE (P, n = 6) according to the percentage of lung involved by either form. Preoperative pulmonary function tests and the score of inflammation and the diameters of the small airways were also measured. Mean linear intercept (Lm), a measure of mean interalveolar wall distances and forced expiratory volume in one second (FEV1) were similar in the four groups. Small airway pathology was a predominant feature in lungs with CLE, and was significantly decreased in a stepwise fashion as the amount of PLE increased. This was especially so for the amount of muscle in the airway wall and the diameters of the airways. By contrast, lung compliance was higher in panacinar than in centrilobular emphysema.(ABSTRACT TRUNCATED AT 250 WORDS)
Aged↗
Morphological and cellular basis for airflow limitation in smokers.
Airflow limitation has two well-defined components, increased resistance, which is found predominantly in the small airways, and loss of elastic recoil. Small airways contribute to the increased resistance to flow by the narrowing of the airway lumen. Morphometric studies have shown that smokers have increased epithelial abnormalities, cellular inflammatory infiltrates in the airway wall, increased muscle and fibrosis, when compared with nonsmokers. Along with these anatomical changes, an increased percentage of airways < 400 microns in diameter is found. In addition to the measured changes, other nonmeasurable, dynamic events occur in the airways of smokers, which further decrease lumen diameter. There is ample evidence to show that the airways of smokers react to nonspecific stimuli by constricting, which results in increased resistance and decreased forced expiratory volume in one second (FEV1). The pathological changes found in smokers, that could be responsible for active muscle constriction and airway narrowing include: 1) airway epithelial damage, resulting in increased permeability and impairment of other epithelial function; 2) chronic airway inflammation; 3) structural changes in the airway wall; and 4) loss of alveolar attachments. However, not all smokers develop the abovementioned airway abnormalities. We describe how smokers could develop either centrilobular emphysema (CLE), or panlobular emphysema (PLE). We have found that smokers with CLE have more abnormal and narrower small airways, and flow limitation is correlated with the small airway abnormalities and not with loss of recoil. In contrast, smokers with PLE have much less severe airway abnormalities, diffuse emphysema that can be detected microscopically at a stage when FEV1 might be only mildly abnormal, and early changes in elastic recoil as evidenced by the changes in the pressure-volume curve of the lung. Furthermore, in PLE, airflow limitation is correlated with loss of recoil but not with abnormalities in the small airways. We believe that the mechanisms involved in the pathogenesis of the two types of emphysema in smokers are different; an airborne mechanism for CLE, possibly related to airway hyperresponsiveness, and a bloodborne mechanism for PLE, which may be related to dysfunction of alpha 1-antiproteases. We conclude that the separation of smokers based on their emphysema type is essential if we are to understand the pathogenesis of chronic obstructive pulmonary disease (COPD) in these subjects.
Bronchi↗
Low molecular weight pollutants and asthma: pathogenetic mechanisms and genetic factors.
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Air Pollutants↗
CD8 T-cell clones producing interleukin-5 and interferon-gamma in bronchial mucosa of patients with asthma induced by toluene diisocyanate.
OBJECTIVES: The aims of the present study were to determine whether specific in vivo stimulation of asthmatics sensitized with toluene diisocyanate (TDI) induces the activation of T lymphocytes in bronchial mucosa and to characterize their phenotype and cytokine secretion profile. METHODS: Bronchial biopsies from two subjects with occupational asthma due to TDI were obtained 48 h after an asthmatic reaction induced by an inhalation challenge with TDI and after three months of no exposure to TDI, at the time when the subjects had recovered from their asthma. The fragments of bronchial mucosa were cultured in the presence of interleukin-2 so that the in vivo activated T cells present in the tissue would expand, and T blasts were then cloned under limiting dilution conditions. RESULTS: From the two 48-h specimens, 65 and 63 T-cell clones were obtained. Most of the clones exhibited the CD8 phenotype (82 and 83%). All of the CD8 clones produced interferon-gamma and 44% produced interleukin-5, but only 6% secreted interleukin-4 as well. Three months after the cessation of exposure, growing T cells could not be recovered from bronchial biopsies cultured in interleukin-2. CONCLUSIONS: The results suggest that, in sensitized subjects, exposure to TDI induces the activation of a subset of CD8 lymphocytes producing interferon-gamma and interleukin-5.
Adult↗