PubMed Health⌕ Search

Biomedical subjects

M Saetta

Publications and source records attributed to M Saetta.

At least 73 records · Page 4Linked to original sources
PubMed1994

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↗
PubMed1994

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↗
PubMed1994

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↗
PubMed1994

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↗
PubMed1994

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↗
PubMed1994

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↗
PubMed1994

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↗
PubMed1994

Structural aspects of airway inflammation in COPD.

Descriptions of pathology of chronic bronchitis in the past have been mainly focused on mucous gland hypertrophy, since this was considered the morphologic basis of the disease, but more recent studies have suggested a pathogenetic role for airway inflammation in subjects with chronic bronchitis. In the present review, we briefly summarize the results of these latter studies, which describe the nature of airway inflammation and the state of activation of inflammatory cells in the bronchial mucosa of subjects with chronic bronchitis.

Bronchitis↗
PubMed1993

Toluene diisocyanate-stimulated release of arachidonic acid metabolites in the organ bath from guinea-pig airways.

This study was designed to evaluate whether metabolites of arachidonic acid play a role in the contractile response to toluene diisocyanate in isolated guinea pig airways. In control experiments we collected the supernatant from an organ bath over a time period of 2 h, after the addition of toluene diisocyanate (100 and 300 microM), and after the addition of toluene diisocyanate (300 microM) in the presence of indomethacin (5 microM). We measured prostaglandin E2, 6-keto-prostaglandin F1 alpha, prostaglandin F2 alpha, thromboxane B2, leukotriene B4, leukotriene C4/D4/E4/F4 by radioimmunoassays. Levels of prostaglandin F2 alpha and 6-keto-prostaglandin F1 alpha increased significantly after addition of toluene diisocyanate in the absence of indomethacin. These results suggest that prostaglandins are involved in toluene diisocyanate-induced contractions in guinea-pig airways.

Animals↗
PubMed1993

The effect of compound 48/80 on contractions induced by toluene diisocyanate in isolated guinea-pig bronchus.

We have investigated the ability of compound 48/80 and of histamine H1 and H2 receptor antagonists to inhibit toluene diisocyanate-induced contractions in isolated guinea-pig bronchi. Compound 48/80 (100 micrograms/ml) significantly inhibited toluene diisocyanate-induced contractions. By contrast, the two histamine H1 and H2 receptor antagonists, chlorpheniramine (10 microM) and cimetidine, (10 microM) did not affect toluene diisocyanate-induced contractions, but significantly inhibited contractions induced by exogenously applied histamine (100 microM) and by 48/80. We investigated which mechanisms 48/80 used to inhibit toluene diisocyanate-induced contractions, paying particular attention to the possible involvement of capsaicin-sensitive primary afferents. In vitro capsaicin desensitization (10 microM for 30 min followed by washing) significantly reduced compound 48/80-induced contractions. A capsaicin-resistant component of contraction was also evident. Ruthenium red (3 microM), an inorganic dye which acts as a selective functional antagonist of capsaicin, did not affect 48/80-induced contraction. MEN 10,207 (Tyr5,D-Trp6,8,9,Arg10)-neurokinin A (4-10) (3 microM) a selective antagonist of NK2-tachykinin receptors significantly reduced 48/80-induced contractions. These results show that compound 48/80 inhibits toluene diisocyanate-induced contractions in isolated guinea-pig bronchi. It is likely that two mechanisms are involved in the inhibition: (1) the release of mediators other than histamine by mast cells, (2) an effect of 48/80 on sensory nerves.

Animals↗
PubMed1993

Effect of bumetanide on toluene diisocyanate induced contractions in guinea pig airways.

BACKGROUND: The loop diuretic frusemide has been shown to inhibit the bronchoconstrictor response to exercise, inhaled allergen, distilled water, adenosine, and sodium metabisulphite. Toluene diisocyanate contracts smooth muscle by activating capsaicin sensitive nerves and causes asthma that shares many features with allergen induced asthma. METHODS: The study was designed to assess the effect of two loop diuretics, bumetanide (10 and 100 microM) and frusemide (100 microM), on smooth muscle contraction induced by toluene diisocyanate (0.03-1000 microM) in guinea pig airways with and, in the case of bumetanide, without epithelium. The effect of bumetanide on the response to acetylcholine, neurokinin A, and electrical field stimulation in guinea pig bronchial smooth muscle rings was also examined. RESULTS: Bumetanide (10 and 100 microM) had no effect on toluene diisocyanate induced contraction whether airway epithelium was present or not. Frusemide (100 microM) caused no significant inhibition of toluene diisocyanate induced contraction (mean reduction on the entire curve 25%). Bumetanide inhibited non-adrenergic, non-cholinergic contraction induced by electrical field stimulation of bronchi pretreated with atropine (1 microM) and indomethacin (5 microM) and this inhibition was inversely related to the frequency of stimulation, suggesting that bumetanide may be inhibiting transmitter release at the prejunctional level. Bumetanide and frusemide did not inhibit the responses to exogenous acetylcholine (0.1 microM) or neurokinin A (1 nM). CONCLUSIONS: Bumetanide and frusemide in doses that are known to inhibit non-adrenergic, non-cholinergic contraction due to electrical field stimulation failed to inhibit the response to toluene diisocyanate in guinea pig airways.

Acetylcholine↗
PubMed1993

Activated T-lymphocytes and macrophages in bronchial mucosa of subjects with chronic bronchitis.

To examine the nature and the degree of leukocyte infiltration and to determine the state of activation of cells in bronchial mucosa of subjects with chronic bronchitis, bronchoscopy was performed in 10 subjects with a history of cigarette smoking and chronic sputum production and in six normal nonsmoking control subjects. Lobar bronchial biopsies were examined using histochemical and immunohistochemical techniques. Subjects with chronic bronchitis had an increased number of total leukocytes (CD45 positive cells), both in the epithelium and in the lamina propria, than did the control subjects (p < 0.05), whereas the numbers of neutrophils, eosinophils, and mast cells were similar in the two groups. There was a significant increase in the numbers of macrophages (p < 0.01) and of T-lymphocytes (CD3 positive cells) (p < 0.05) in the lamina propria of chronic bronchitics, whereas the relative proportions of CD4 and CD8 positive cells were similar in the bronchitics and the control subjects. Subjects with chronic bronchitis also had an increased expression of markers of lymphocyte activation, i.e., an increased number of interleukin-2 receptor positive cells (CD25 positive cells) (p < 0.05) and an increased number of very late activation antigen (VLA-1) positive cells (p < 0.05). In conclusion, the present study provides evidence for mononuclear cell infiltration and for T-cell activation in bronchial mucosa of subjects with chronic bronchitis, supporting the involvement of these cells in the pathogenesis of the disease.

Adult↗
PubMed1993

Mast cells in the airway mucosa and rapid development of occupational asthma induced by toluene diisocyanate.

We examined lobar bronchial biopsies taken from 18 subjects with occupational asthma induced by toluene diisocyanate (TDI) and from nine nonasthmatic control subjects. Two groups of asthmatics were identified on the basis of the duration of exposure to TDI before the onset of symptoms of asthma. Group A (n = 8) developed asthma after 2.4 +/- 0.4 yr of exposure to TDI, and Group B (n = 10) developed asthma after 21.6 +/- 3.1 yr of exposure to TDI. Both groups of asthmatic subjects had increased numbers of inflammatory cells in the airway mucosa compared with subjects in the nonasthmatic control group. Comparison between Groups A and B showed that subjects who developed asthma after short-term exposure had a significantly increased number of mast cells both in epithelium and in lamina propria than did subjects who developed asthma after long-term exposure to TDI (p < 0.01). Interestingly, the numbers of mast cells both in the epithelium (rs = -0.52, p < 0.05) and in the lamina propria (rs = -0.81, p < 0.001) were inversely correlated with the length of exposure to TDI before the onset of asthma. In conclusion, subjects who develop asthma after short-term exposure to TDI have an increased number of mast cells in the airway mucosa, suggesting that these cells may be associated with individual susceptibility differences to offending agents.

Adult↗
PubMed1993

Effects of inhaled beclomethasone on airway responsiveness in occupational asthma. Placebo-controlled study of subjects sensitized to toluene diisocyanate.

We investigated the effect of 5 months of treatment with inhaled beclomethasone dipropionate (BDP) on the airway responsiveness to methacholine (PD20 FEV1) and to toluene diisocyanate (TDI) in 15 sensitized asthmatic subjects who had been removed from occupational exposure to TDI. After the diagnosis was established by a positive inhalation challenge with TDI, each subject was removed from occupational exposure to isocyanates and treated with either BDP (1 mg twice per day, n = 7) or placebo (n = 8) for 5 months. The study was double blind for parallel groups. P20 FEV1 methacholine was measured before and three times during treatment and then at 6 months, that is, 4 wk after cessation of treatment. Airway sensitivity to TDI was assessed with specific inhalation challenge before treatment and at 6 months. Beclomethasone reduced the airway hyperresponsiveness to methacholine but did not affect the response to TDI. In fact, in the subjects on BDP, P20 FEV1 increased from 0.145 to 0.485 mg (p < 0.05) after 2 months of treatment. A further increase was observed at 4 and 5 months (0.548 and 0.629 mg, respectively, p < 0.01), and the improvement in nonspecific airway responsiveness was maintained after a 1-month washout period (0.637 mg, p < 0.01). In contrast, in the subjects on placebo, P20 FEV1 did not change significantly. At the end of the study, the severity of asthmatic reactions induced by bronchial challenge with TDI was significantly reduced in both groups, but no differences were observed between placebo and BDP.(ABSTRACT TRUNCATED AT 250 WORDS)

Adolescent↗
PubMed1992

Activated T-lymphocytes and eosinophils in the bronchial mucosa in isocyanate-induced asthma.

We have studied the phenotype and activation status of leukocytes in the bronchial mucosa in patients with isocyanate-induced asthma. Fiberoptic bronchial biopsy specimens were obtained from nine subjects with occupational (five toluene- and four methylene diisocyanate-sensitive) asthma, 10 subjects with extrinsic asthma, and 12 nonatopic healthy control subjects. Bronchial biopsy specimens were examined by immunohistology with a panel of monoclonal antibodies and the alkaline phosphatase-antialkaline phosphatase method. There was a significant increase in the number of CD25+ cells (interleukin-2 receptor-bearing cells, presumed "activated" T-lymphocytes; p less than 0.01) in isocyanate-induced asthma compared with that of control subjects. There were also significant increases in major basic protein (BMK-13)-positive (p less than 0.02) and EG2-positive (p less than 0.01) cells that represent total and "activated" eosinophil cationic protein-secreting eosinophils, respectively. In agreement with our previous findings, CD25+ (p less than 0.01), BMK-13 (p less than 0.03), and EG2+ (p less than 0.01) cells were also elevated in extrinsic asthma. No significant differences were observed in the numbers of T-lymphocyte phenotypic markers (CD3, CD4, and CD8) between subjects with asthma (isocyanate-induced and extrinsic) and control subjects. Similarly, no significant differences in immunostaining for neutrophil elastase (neutrophils) or CD68 (macrophages) were observed. The results suggest that isocyanate-induced occupational asthma and atopic (extrinsic) asthma have a similar pattern of inflammatory cell infiltrate. The results support the view that T-lymphocyte activation and eosinophil recruitment may be important in asthma of diverse etiology.

Adult↗
PubMed1992

Airway mucosal inflammation in occupational asthma induced by toluene diisocyanate.

We examined the light and electron microscopic structure of lobar bronchial biopsies of nine subjects with occupational asthma induced by toluene diisocyanate (TDI) and of four control nonasthmatic subjects who had never been exposed to TDI. Inflammatory cell numbers were separately 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. Eosinophils were significantly increased in all compartments, CD45-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 epithelium. By electron microscopy eosinophils 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 were similar in asthmatic and control groups, the intercellular spaces between basal cells were significantly wider in patients with asthma. Patients with TDI-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 TDI, the airway mucosa shows pathologic features, such as inflammatory cell infiltrate and thickening of subepithelial collagen, similar to those described in atopic asthma.

Adolescent↗