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Biomedical subjects

J A Nadel

Publications and source records attributed to J A Nadel.

At least 19 recordsLinked to original sources
PubMed1992

Neutral endopeptidase modulates endothelin-1-induced airway smooth muscle contraction in guinea-pig trachea.

This study was designed to evaluate the role of neutral endopeptidase (NEP) in modulating the airway smooth muscle contraction induced by endothelin-1 in isolated segments of guinea-pig trachea. Endothelin-1 (10(-9)-10(-6) M) produced a concentration-dependent contraction that reached a maximum by 30 min. The NEP inhibitor leucine-thiorphan (10(-5) M) significantly increased the contractile response to endothelin-1. The addition of leucine-thiorphan to tracheal segments precontracted by 10(-9) and 10(-8) M endothelin-1 increased isometric tension by 181 +/- 65% (mean +/- 1 S.E.M.; P less than 0.05) and by 138 +/- 49% (P less than 0.05), respectively. In contrast, the kininase II inhibitor captopril and the peptidase inhibitors leupeptin and bestatin had no effect. Preincubation of endothelin-1 with 1 microgram recombinant human NEP decreased the contractile activity of endothelin-1 by 72 +/- 9%, whereas no effect was observed using heat-inactivated NEP. We conclude that NEP modulates endothelin-induced contraction of airway smooth muscle in the guinea-pig trachea.

Animals↗
PubMed1992

Substance P-immunoreactive sensory axons in the rat respiratory tract: a quantitative study of their distribution and role in neurogenic inflammation.

Substance P is one of the peptides released from sensory nerves that mediate "neurogenic inflammation." Although substance P-immunoreactive (SP-IR) axons are known to be present within the mucosa of the respiratory tract, the relative extent of the innervation of various components of the mucosa is not known. Therefore, we determined the distribution and number of SP-IR axons in the rat trachea and bronchi, by using immunohistochemistry on tissue whole mounts. Specifically, we sought to learn whether these axons directly innervate the postcapillary venules involved in neurogenic plasma extravasation, the arterioles involved in neurogenic vasodilatation, and the airway smooth muscle involved in bronchoconstriction in pathogen-free, adult male F344 rats. We found that 90% of the SP-IR axons were single axons, usually having varicosities. Eighty-five percent of these were in the epithelium, 6% innervated arterioles, and the remainder elsewhere in the lamina propria. Only 10% of the mediator-sensitive postcapillary venules (i.e., venules labeled with Monastral blue pigment after challenge with capsaicin or substance P) were within 10 microns of SP-IR axons. SP-IR axons were more than 10 times as frequent in the smooth muscle of the distal bronchi as in the trachea. Capsaicin pretreatment (168 mg/kg over 7 days) reduced the number of SP-IR axons in the trachea by 96%, which is consistent with their being sensory. Unilateral vagotomy reduced the number of SP-IR axons bilaterally in the trachea and ipsilaterally in the main stem bronchus. Using an antibody to Protein Gene Product 9.5 as a nonspecific marker for all nerves in the trachea, we determined that SP-IR axons constituted 90% of the axons in the epithelium, 32% of the axons on arterioles, and only 4% of the axons in the smooth muscle. We conclude that most SP-IR nerves in the trachea are sensory axons and most of these axons end in the epithelium. SP-IR axons innervate mucosal arterioles, but few innervate postcapillary venules. Therefore, the mechanism by which sensory axons evoke plasma extravasation from these venules is likely to involve the diffusion of the peptide or a secondary mediator from the epithelium or from the arterioles upstream.

Animals↗
PubMed1992

Neutrophil elastase stimulates tracheal submucosal gland secretion that is inhibited by ICI 200,355.

To investigate whether human neutrophil elastase (HNE) stimulates airway submucosal gland secretion, we studied the effect of purified HNE on secretion of 35S-labeled macromolecules from isolated tracheal tissues from ferrets, dogs, and humans. HNE stimulated secretion in a concentration-dependent fashion, the secretory response being most pronounced in ferret tissues with a maximal response of 1,498 +/- 384% above baseline at 10(-5) M. In dog tissues, maximal secretory responses (509 +/- 169%) to HNE were much greater than to bethanechol (80 +/- 26%). Human tissues obtained several hours postmortem still responded to HNE (179 +/- 48% at 10(-5) M) significantly more than to the combination of isoproterenol, phenylephrine, and bethanechol (23 +/- 10%). Morphometric analysis of canine tracheal tissues showed degranulation of submucosal gland cells after HNE. A specific inhibitor of HNE (ICI 200,355) potently inhibited secretory responses in a concentration-dependent fashion. We suggest that HNE in airways of patients may cause hypersecretion and that treatment with ICI 200,355 may provide a strategy for therapeutic intervention.

Animals↗
PubMed1992

Interleukin-8 induces neutrophil accumulation but not protease secretion in the canine trachea.

The neutrophil enzyme elastase is a potent secretagogue of airway secretory cells, and elastase is present in high concentrations in sputum of patients with hypersecretion (e.g., cystic fibrosis, bronchiectasis). Interleukin-8 (IL-8), a recently discovered cytokine with potent neutrophil chemotactic properties in vitro, is also found in the sputum of these patients. We used an isolated tracheal segment in dogs in vivo to study the effect of IL-8 in causing neutrophil accumulation, elastase release, and secretion (by measuring lysozyme concentrations) in the luminal superfusate. IL-8 caused a potent time-dependent neutrophil accumulation at between 3 and 6 h. The effect was significant at 10(-9) and maximum at 10(-8) M. No increase in free elastase, cathepsin G, or lysozyme was detected in the superfusate. Thus, in contrast to previous studies showing that ragweed antigen causes the accumulation of neutrophil elastase which in turn causes lysozyme secretion, IL-8 causes neutrophil accumulation without granule secretion (or subsequent secretagogue activity). The findings were confirmed with dog and human neutrophils in vitro.

Animals↗
PubMed1992

Effect of neuropeptides released from sensory nerves on blood flow in the rat airway microcirculation.

Stimulation of sensory nerves in the airway mucosa causes local release of the neuropeptides substance P and calcitonin gene-related peptide (CGRP). In this study we used a modification of the reference-sample microsphere technique to measure changes in regional blood flow and cardiac output distribution produced in the rat by substance P, CGRP, and capsaicin (a drug that releases endogenous neuropeptides from sensory nerves). Three sets of microspheres labeled with different radionuclides were injected into the left ventricle of anesthetized F344 rats before, immediately after, and 5 min after left ventricular injections of capsaicin, substance P, or CGRP. The reference blood sample was withdrawn from the abdominal aorta and was simultaneously replaced with 0.9% NaCl at 37 degrees C. We found that stimulation of sensory nerves with a low dose of capsaicin causes a large and selective increase in microvascular blood flow in the extrapulmonary airways. The effect of capsaicin is mimicked by systemic injection of substance P but not by CGRP, suggesting that substance P is the main agent of neurogenic vasodilation in rat airways.

Animals↗
PubMed1992

Role of neutrophil elastase in allergen-induced lysozyme secretion in the dog trachea.

To test our hypothesis that neutrophil elastase plays a role in airway hypersecretion associated with the allergic late-phase response, using an isolated tracheal segment system in vivo and measuring lysozyme activity in the perfusate of the lumen as a marker of submucosal gland secretion over 8 h, we studied the response of five allergic dogs to ragweed. The dogs were exposed on separate occasions to specific allergen, to allergen vehicle, and to allergen in the presence of a selective neutrophil elastase inhibitor, ICI 200,355. Allergen exposure caused a marked increase in lysozyme secretion that was significantly increased at 4, 6, and 8 h compared with controls and ICI 200,355-treated dogs. Neutrophil elastase appeared in the perfusate after allergen exposure and was positively correlated with lysozyme secretion at 8 h. These findings suggest that neutrophil elastase plays an important role as a secretagogue in the allergic late-phase response.

Allergens↗
PubMed1992

Mucus hypersecretion in bronchiectasis. The role of neutrophil proteases.

To investigate the role of neutrophil proteases in the pathogenesis of mucus hypersecretion in bronchiectasis, we collected sputum samples from seven patients with bronchiectasis and measured their secretagogue activity by examining secretion of radiolabeled macromolecules by bovine airway submucosal gland cells incubated with sputum supernatants. There was marked secretagogue activity in bronchiectasis sputum, reaching a maximum of 1,963 +/- 292% (mean +/- SEM) above baseline at 1:15 dilution. Addition of ICI 200,355 (10(-5) M), a selective human neutrophil elastase inhibitor, decreased the secretory response markedly (72.53 +/- 5.89% reduction). The combination of aprotinin, an inhibitor of cathepsin G, and ICI 200,355 caused significantly more reduction in the secretory response than ICI 200,355 alone (89.12 +/- 3.8 versus 72.53 +/- 5.89% reduction, p < 0.05). We conclude that bronchiectasis sputum causes a large secretory response from tracheal submucosal glands due mostly to neutrophil proteases.

Adult↗
PubMed1992

Distribution of chymase-containing mast cells in human bronchi.

Mast cell chymase stimulates secretion from cultured airway gland serous cells and hydrolyzes bronchoactive peptides in vitro. To explore the likelihood of these interactions occurring in situ, we examined the distribution and concentration of chymase-containing mast cells near glands and smooth muscle of major human bronchi from eight individuals without known airway disease. Total airway mast cells and the subset of mast cells containing chymase were detected by staining for methylene blue metachromasia and chloroacetate esterase activity, respectively. The percentage of chymase-containing mast cells was found to differ strikingly among bronchial tissue compartments. Near glands, for example, the concentration of chymase-positive mast cells (640 +/- 120 cells/mm3) was 73 +/- 9% that of total mast cells (910 +/- 130 cells/mm3), whereas in smooth muscle the concentration of chymase-positive mast cells (450 +/- 200 cells/mm3) was only 14 +/- 4% that of total mast cells (2920 +/- 620 cells/mm3). Of all chymase-containing mast cells in the airway subepithelium, 30 +/- 4% were located within 20 microns of submucosal glands. Although the percentage of chymase-containing cells varied, the absolute concentration of chymase-containing mast cells was similar in all compartments. These results reveal a differential distribution of mast cell subpopulations in human airway and suggest that mast cells containing chymase are near gland and smooth muscle targets.

Bronchi↗
PubMed1991

Bronchial smooth muscle responses evoked by toluene diisocyanate are inhibited by ruthenium red and by indomethacin.

We have investigated the ability of ruthenium red, an inorganic dye with Ca2+ entry-blocking properties and a selective antagonist of capsaicin, and of indomethacin, a cyclooxygenase inhibitor, to inhibit bronchial smooth muscle responses evoked by toluene diisocyanate in guinea pigs. Previous exposure of isolated guinea pig bronchi to ruthenium red significantly decreased the response produced by toluene diisocyanate. Further, the response to toluene diisocyanate was significantly decreased by pretreatment with indomethacin. These findings provide evidence that toluene diisocyanate-induced contractions of guinea pig bronchi are produced indirectly by generation of a prostanoid that activates capsaicin-sensitive afferents via a ruthenium red-sensitive mechanism.

Animals↗
PubMed1991

Inhibition of human neutrophil elastase by ICI 200,355.

To examine the pathogenetic role of neutrophil elastase in airway hypersecretion, we have studied the novel inhibitor of this enzyme, [4-(4-bromophenylsulfonylcarbamoyl)benzoyl-L-valyl-L-proline 1 (RS)-(1-trifluroacetyl-2-methylprolyl)amide] (ICI 200, 355). This compound was a potent (Ki = 0.6 +/- 0.22 nM) inhibitor of human neutrophil elastase and a much weaker inhibitor of other hydrolases. ICI 200,355 also inhibited the ongoing destruction of insoluble elastin by human neutrophil elastase. ICI 200,355 produced a concentration-dependent inhibition of the secretory response induced by human neutrophil elastase (10(-8) M), with an IC50 of 1.6 x 10(-8) M. ICI 200,355 had no effect on baseline secretion or on the secretory response to chymase, cathepsin G or Pseudomonas aeruginosa elastase. Thus, ICI 200,355 appears to be a useful tool for investigating the role of human neutrophil elastase in inflammatory disorders associated with hypersecretion, such as cystic fibrosis, chronic bronchitis, and asthma.

Elastin↗
PubMed1991

Infection of cultured human airway epithelial cells by influenza A virus.

The lack of an adequate in vitro model has hampered study of the cellular basis by which influenza A virus causes disease in the human airway. We report in vitro infection of human airway epithelial cells by influenza A virus. Fetal and adult human tracheal and bronchial epithelial cells cultured from explants and SV40 transformed adult human tracheal epithelial cells were exposed to a recently isolated strain of influenza A virus (H1N1) and a laboratory passaged strain (WSN) of influenza A virus at similar multiplicity of infection. All cultures derived from explants showed hemadsorption (approximately 30% of the cells) with the H1N1 virus. No hemadsorption was detected with the WSN virus. One of two transformed cell lines showed a 5-10% hemadsorption to cells after H1N1 exposure and none following exposure to WSN. Immunofluorescent staining for influenza A-specific antigens in virus-exposed, explant-derived cells indicated viral infection and replication in these cells. Hemagglutinating material in the growth medium of infected, explant-derived cell lines, increased as a function of time, indicating the production of virus proteins. Exposure of rhesus monkey kidney cells and new human tracheal epithelial cultures to supernatant from these cells resulted in hemadsorption, indicating the presence of infectious virus in the supernatant. Light microscopic examination of virally infected bronchial epithelial cells demonstrated that the common types of cytopathic changes were rarely seen while cell proliferation continued over time. The data indicate that influenza A virus can infect, replicate, and produce infectious virus in cultured human tracheal and bronchial epithelial cells.

Animals↗