Biomedical subjects

J A Nadel

Publications and source records attributed to J A Nadel.

At least 73 records · Page 4Linked to original sources

PubMed1995

Elevated intracellular cyclic AMP inhibits chemotaxis in human eosinophils.

Elevated intracellular cyclic AMP is associated with the inhibition of many inflammatory cellular responses. In this study, we examined the effect of cyclic AMP on eosinophil chemotaxis. Eosinophils were isolated from healthy human volunteers using an immunomagnetic method. Eosinophils were treated with agents that elevate intracellular cyclic AMP and evaluated for chemotactic responses to platelet-activating factor (PAF; 10(-6) M) and to complement factor 5a (C5a; 10(-8) M) in microchemotaxis chambers. Forskolin, prostaglandin E1 (PGE1), and a phosphodiesterase (PDE) IV-selective inhibitor inhibited eosinophil chemotactic responses. The mean per cent inhibition of eosinophil chemotaxis in response to PAF by forskolin, PGE1, and the PDE IV-selective inhibitor (10(-5) M) was 16.8 +/- 5.3, 26.6 +/- 9.5, and 35.1 +/- 6.1%, respectively (n = 5). The corresponding values for C5a were 17.5 +/- 7.9, 20.8 +/- 10.7, and 39.5 +/- 5.0%. An exogenous cyclic AMP analogue (dibutyryl cyclic AMP, 10(-3) M) also inhibited eosinophil chemotaxis by 69.4 +/- 12.8 and 66.9 +/- 11.6% in response to PAF and C5a, respectively (n = 5). We conclude that elevated intracellular cyclic AMP inhibits eosinophil chemotaxis.

Alprostadil↗

PubMed1995

Inhibition of bronchoconstriction by pituitary adenylate cyclase activating polypeptide (PACAP 1-27) in guinea-pigs in vivo.

1. We studied the inhibitory effect of pituitary adenylate cyclase activating polypeptide (PACAP 1-27) on the increase in total pulmonary resistance (RL) caused either by allergen or histamine in anaesthetized, ventilated guinea-pigs. 2. PACAP 1-27 given via i.v. infusion (0.045-4.5 nmol kg-1 min-1) dose-dependently reduced the increase in RL caused by inhaled ovalbumin and histamine. At the highest dose, PACAP 1-27 prevented the increase in RL caused by ovalbumin and histamine completely. Infusion of PACAP 1-27 and the beta 2-adrenoceptor agonist, salbutamol (0.045-4.5 nmol kg-1 min-1) inhibited the increase in RL similarly, but salbutamol increased the heart rate more than PACAP 1-27. 3. PACAP 1-27 and salbutamol given via inhaled aerosol (0.1 mM, 20 breaths) significantly reduced the increase in RL caused by histamine infused i.v., whereas aerosolised sterile saline did not. Both PACAP 1-27 and salbutamol caused bronchodilator effects within 1 min of drug inhalation and these effects remained throughout the 20 min of study. 4. Because PACAP 1-27 produced significant bronchodilatation and rapid onset of sustained action in vivo and without pronounced cardiovascular side effects, we conclude that this peptide may have therapeutic potential as a bronchodilator.

Adenylyl Cyclases↗

PubMed1995

New aspects on the role of kinins in neurogenic inflammation.

The inflammatory response to injury consists of the activation of several protective mechanisms involving different cellular systems. Among the mechanisms and systems that exert their effects rapidly, peptide transmitters released from peripheral endings of primary sensory neurons (evoking neurogenic inflammation) play a major role in the response to tissue injury. Noxious stimuli may directly activate sensory nerves to release proinflammatory neuropeptides. More recently, evidence has accumulated suggesting that indirect mechanisms leading to sensory neuropeptide release are also activated in relevant models of pathophysiological conditions. Tachykinin NK1 and NK2 receptor antagonists reduced the plasma extravasation in the trachea and nasal mucosa and the bronchoconstriction caused by antigen challenge in sensitized guinea-pigs. Blockage of kinin B2 receptors with the selective antagonist HOE-140 had a similar inhibitory effect. The magnitude of the inhibition observed with the kinin receptor antagonist alone was similar to that caused by a combination a tachykinin and kinin receptor antagonists. This suggests activation of a common final pathway by these two groups of mediators. Pharmacological and biochemical evidence suggests that in the airways of sensitized guinea-pigs, kinins released by the anaphylactic reaction stimulate the release of tachykinins from sensory nerves, thus contributing to their proinflammatory action.

Anaphylaxis↗

PubMed1995

Staphylococcus aureus stimulates neutrophil recruitment by stimulating interleukin-8 production in dog trachea.

The present study examined whether neutrophil recruitment in dog airways by Staphylococcus aureus is mediated by interleukin-8 (IL-8). S. aureus culture supernatant was superfused into an isolated tracheal segment in six dogs, and neutrophil recruitment and IL-8 concentrations were measured in the superfusate. Dog IL-8 was cloned, expressed in Escherichia coli, purified by chromatography, and shown to be biologically active. With the use of an enzyme-linked immunoabsorbent assay (ELISA) for the measurement of dog IL-8, we showed that S. aureus supernatant induced neutrophil recruitment and increased IL-8 concentration in the superfusate in a time-dependent manner. The chemotactic activity present in the superfusate 6 h after superfusion with S. aureus was inhibited by an anti-IL-8 antibody. S. aureus supernatant also stimulated IL-8 production and gene expression by cultured canine tracheal epithelial cells. These results provide evidence that IL-8 plays a major role in S. aureus-induced neutrophil recruitment in the airways by stimulating IL-8 production in airway cells.

Amino Acid Sequence↗

PubMed1995

NK1 receptors mediate leukocyte adhesion in neurogenic inflammation in the rat trachea.

In neurogenic inflammation, tachykinins trigger the adhesion of neutrophils and eosinophils to leaky venules. The goals of the present study were to determine whether this leukocyte adhesion is mediated by neurokinin type 1 (NK1) receptors and to determine whether the amount of leukocyte adhesion corresponds to the amount of plasma leakage. Anesthetized rats were injected intravenously with substance P, the NK1 receptor agonist [Sar9, Met(O2)11]-substance P, or the NK2 receptor agonist [beta-Ala8]neurokinin A-(4-10). Five minutes later, the adherent neutrophils and eosinophils in blood vessels of the tracheal mucosa were stained histochemically and plasma leakage was quantified, as assessed by the extravasation of Monastral blue. Substance P and the NK1 agonist caused similar amounts of leukocyte adhesion, but the NK2 agonist had no effect. Pretreatment with the NK1 receptor antagonist CP-96,345 (4 mg/kg iv), before challenge with substance P, capsaicin, or aerosol hypertonic saline, reduced the amount of neutrophil adhesion by 56%, 93%, and 57% and reduced the amount of eosinophil adhesion by 70%, 83%, and 65%, respectively. Plasma extravasation was decreased by 89%, 95%, and 94%. The number of adherent neutrophils in the trachea was strongly correlated with the number of adherent eosinophils (r2 = 0.61). The greatest amount of leukocyte adhesion occurred in larger diameter venules than did the maximal amount of Monastral blue leakage. We conclude that NK1 receptors mediate the adhesion of neutrophils and eosinophils as well as the plasma leakage triggered by substance P, capsaicin, or hypertonic saline. This leukocyte adhesion evidently does not occur at exactly the same sites as the plasma leakage.

Animals↗

PubMed1995

Viral infection potentiates the increase in airway blood flow produced by substance P.

We examined the effect of respiratory tract infection with Sendai virus on the responsiveness of airway blood flow to substance P (SP) in rats. Pathogen-free rats were inoculated with either Sendai virus suspension or sterile viral growth medium into each nostril. Five days later, we measured airway and esophageal blood flows before and immediately after injection of SP or histamine into the left ventricle of rats in both groups using a modification of the reference-sample microsphere technique. Viral infection potentiated the increase in airway blood flow evoked by SP but not by histamine. We also examined the effect of neutral endopeptidase (NEP) and angiotensin-converting enzyme (ACE) on the SP-induced increase in airway blood flow. Both phosphoramidon (NEP inhibitor) and captopril (ACE inhibitor) potentiated the increase in airway blood flow produced by SP in pathogen-free rats. In the presence of both peptidase inhibitors, a submaximal dose of SP increased blood flow to a similar level in infected and pathogen-free rats. Thus decreased activity of both ACE and NEP may be involved in the exaggerated increase in airway blood flow evoked by SP in virus-infected rats.

Angiotensin-Converting Enzyme Inhibitors↗

PubMed1995

Effect of an NK1 receptor antagonist (CP-99,994) on hypertonic saline-induced bronchoconstriction and cough in male asthmatic subjects.

To investigate the role of NK1 receptors in the pathogenesis of bronchoconstriction and cough in asthma, we performed a randomized, double-blind, crossover study on the effects of a selective non-peptide tachykinin NK1 receptor antagonist (CP-99,994) on baseline measures of lung function and on hypertonic saline-induced bronchoconstriction and cough in 14 male subjects with mild asthma. CP-99,994 (250 micrograms/2 hours) and placebo were administered intravenously in 2-h infusions during consecutive visits 5 to 7 d apart. Specific airway resistance (SRaw) was measured and spirometry was performed at baseline and at 35 and 60 min. Next, hypertonic saline challenge was performed by delivering 10 breaths of saline of increasing concentration (0.9 to 7% in 1% increments at 5-min intervals) via an ultrasonic nebulizer until SRaw increased from baseline by 200% or 20 units, whichever was greater. Throughout the challenge cough was counted from a taped record made from two microphones placed close to the subject's larynx. We found that CP-99,994 did not significantly affect SRaw or spirometric measures of lung function during the first hour of infusion. Although CP-99,994 infusion markedly attenuated the bronchoconstrictor response to the saline challenge in two subjects, it did not significantly decrease the area under curves obtained for SRaw and cough during saline challenge for the group as a whole (p = 0.9 for SRaw;p = 0.8 for cough). We conclude that administration of 250 micrograms/kg of CP-99,994 over 2 h does not significantly inhibit hypertonic saline-induced bronchoconstriction or cough in subjects with mild asthma and does not have acute bronchodilator activity in these subjects.

Adult↗

PubMed1995

Plasma extravasation in the rat trachea induced by cold air is mediated by tachykinin release from sensory nerves.

Cold air was delivered to anesthetized, artificially ventilated, pathogen-free F344 rats via a tracheal cannula. Inhalation of cold air increased Evans blue dye extravasation in the trachea in a time-dependent (1 to 10 min) manner. Plasma extravasation increased after 3 min exposure to cold air and reached a maximum after 10 min exposure. The neutral endopeptidase inhibitor, phosphoramidon (2.5 mg/kg, intravenously), increased by 84% the plasma extravasation induced by inhalation of cold air for 1 min. The plasma extravasation evoked by 5 min exposure to cold air was abolished by the NK1 tachykinin receptor antagonist, CP-99,994 (4 mg/kg, intravenously); was reduced 30% by the B2 bradykinin receptor antagonist, HOE140 (0.1 mumol/kg, intravenously); and was not affected by H1 (pyrilamine, 10 mg/kg, intraperitoneally) or H2 (cimetidine, 10 mg/kg, intraperitoneally) histamine receptor antagonists or the cyclooxygenase inhibitor indomethacin (5 mg/kg, intravenously). In rats infected with Sendai virus, plasma extravasation evoked by inhalation of cold air was greater than in pathogen-free rats. Pretreatment with CP-99,994 (4 mg/kg, intravenously) inhibited completely the plasma extravasation induced by cold air in virus-infected rats. These findings indicate that cold air increases plasma extravasation in the rat trachea by a neurogenic mechanism that involves the release of tachykinins from sensory nerves. Kinin release may also play a role in this neurogenic inflammatory response.

Air↗

PubMed1995

Cystic fibrosis sputum induces a secretory response from airway gland serous cells that can be prevented by neutrophil protease inhibitors.

High activities of the neutrophil proteases, elastase and cathepsin G, are found in the sputum of patients with cystic fibrosis (CF). Because both proteases have been shown to be potent secretagogues for airway submucosal glands, and because hypersecretion is a characteristic feature of CF, the objective of the present study was to examine whether there is secretagogue activity in CF sputum, and to determine the contribution of neutrophil proteases to the secretagogue activity. Confluent monolayers of cultured bovine tracheal serous cells were pulse-labelled with Na2(35)SO4, incubated with diluted CF sputum supernatants in the presence or absence of different protease inhibitors, and the subsequent release of the radio-labelled macromolecules was measured. CF sputum potently induced secretion concentration-dependently. Addition of the selective neutrophil elastase inhibitor ICI 200,355 inhibited the secretory response to CF sputum supernatant by 89%. Addition of a cathepsin G-inhibitor resulted in further inhibition of the secretory response. Addition of phosphoramidon, a drug known to inhibit Pseudomonas aeruginosa elastase, had no effect. We conclude that CF sputum potently stimulates airway submucosal gland cell secretion. These studies with protease inhibitors suggest that neutrophil proteases account substantially for the secretagogue activity present in CF sputum.

Adult↗

PubMed1994

Tachykinins and kinins in antigen-evoked plasma extravasation in guinea-pig nasal mucosa.

The plasma extravasation evoked by instillation of 5% ovalbumin in the nasal mucosa of sensitized guinea-pigs was potentiated by the neutral endopeptidase inhibitor, phosphoramidon, and was reduced by the tachykinin NK1 receptor antagonist, CP-96,345. The bradykinin B2 receptor antagonist, HOE 140, also reduced the plasma extravasation evoked by the antigen. The combination of HOE 140 and CP-96,345 did not increase further the inhibition caused by HOE 140 alone. Plasma extravasation evoked by instillation of capsaicin was abolished by CP-96,345. HOE 140 blocked and CP-96,345 markedly reduced plasma extravasation caused by instillation of bradykinin. Plasma extravasation evoked by instillation of substance P was not affected by HOE 140. We conclude that antigen challenge causes plasma extravasation in the nasal mucosa of sensitized guinea-pigs, an effect that is due in part to the release of tachykinins from sensory nerve endings. Our evidence suggests that tachykinin release in response to antigen is provoked mainly by the release of kinins.

Animals↗

PubMed1994

Role of kinins in anaphylactic-induced bronchoconstriction mediated by tachykinins in guinea-pigs.

1. In the present study, we have investigated the role of kinins in allergen-induced bronchoconstriction. 2. Anaesthetized guinea-pigs were sensitized to ovalbumin, ventilated artificially, pretreated with atropine (1.4 mumol kg-1, i.v.) and total pulmonary resistance (RL) measured. In preliminary studies in the presence of the neutral endopeptidase inhibitor, phosphoramidon (4.5 mumol kg-1, i.v.), the bradykinin B2 receptor antagonist Hoe 140 (0.1 mumol kg-1, i.v.) completely abolished the increase in RL following aerosolized bradykinin (1 mM, 40 breaths), but had no effect on the increase in RL following aerosolized neurokinin A (NKA, 10 microM, 40 breaths). On the other hand, a combination of the NK1 (CP-96,345, 2 mumol kg-1, i.v.) and NK2 (SR 48968, 0.3 mumol kg-1, i.v.) tachykinin receptor antagonists abolished completely the increase in RL produced by NKA and partially inhibited the increase in RL produced by bradykinin. These results confirm previous studies that suggest that bradykinin induces the release of tachykinins from sensory nerves in guinea-pig airways. 3. Aerosolized ovalbumin (0.5%, 5 breaths) increased RL in sensitized guinea-pigs pretreated with atropine (1.4 mmol kg-1, i.v.), an effect that began within 2 min and reached a maximum within 5 min; RL remained above baseline at 20 min. Pretreatment with the bradykinin B2 receptor antagonist, Hoe 140, decreased the bronchoconstrictor effect of ovalbumin markedly at 10 to 20 min. In the presence of phosphoramidon (4.5 mumol kg-1, i.v.) the inhibition induced by Hoe 140 was apparent earlier and remained over the 20 min period of study. 4. Pretreatment with a combination of NK1 (CP-96,345) and NK2 (SR 48968) tachykinin receptor antagonists also markedly inhibited ovalbumin-induced bronchoconstriction; addition of the bradykinin B2 receptor antagonist to the NK1 and NK2 tachykinin receptor antagonists had no additional inhibitory effect on antigen-induced bronchoconstriction.5. These findings confirm that activation of sensory nerves to release tachykinins in guinea-pig airways contribute to antigen-induced bronchoconstriction, and provide evidence that tachykinin release is due to kinins generated during the allergic response.

Adrenergic beta-Antagonists↗

PubMed1994

Evidence for reduction of bradykinin-induced bronchoconstriction in guinea-pigs by release of nitric oxide.

1. In this study the influence of nitric oxide (NO) on the bronchoconstriction induced by bradykinin in anaesthetized and artifically ventilated guinea-pigs pretreated with atropine was investigated. 2. Aerosol administration of bradykinin (0.1-1 mM, 40 breaths) caused a dose-dependent increase in lung resistance (RL): maximum increase in RL was 2.5 fold the baseline value. Pretreatment with aerosolized NG-nitro-L-arginine methyl ester (L-NAME) or NG-monomethyl-L-arginine (L-NMMA) (1 mM, 10 breaths every 5 min for 30 min), NO synthase inhibitors, markedly increased the bronchoconstrictor response to bradykinin. L-Arginine, but not D-arginine, (3 mM, 10 breaths every 5 min for 30 min) reversed the hyperresponsiveness to aerosolized bradykinin caused by L-NAME and L-NMMA. 3. L-NAME (1 mM, 10 breaths every 5 min for 30 min) increased the bronchoconstriction induced by intravenous bradykinin (1-10 nmol kg-1). L-Arginine, but not D-arginine, (10 breaths every 5 min for 30 min) reversed the hyperresponsiveness to intravenous bradykinin caused by L-NAME. 4. The increase in RL induced by capsaicin, either aerosol (10 microM, 10 breaths) or i.v. (20 nmol kg-1) was not affected by L-NAME (1 mM, 10 breaths every 5 min for 30 min). Acute resection of the vagi did not affect the bronchoconstriction evoked by bradykinin in guinea-pigs, either in the absence or presence of L-NAME (1 mM, 10 breaths every 5 min for 30 min). 4. These results suggest that, irrespective of the route of administration, bradykinin releases NO or a related molecule which exerts a bronchodilator action that opposes the bronchoconstrictor mechanisms activated by bradykinin itself.

Aerosols↗

PubMed1994

Airway vasodilation by bradykinin is mediated via B2 receptors and modulated by peptidase inhibitors.

We studied the effect of exogenous bradykinin on blood flow in the airway microcirculation of anesthetized F344 rats in vivo. We made three successive determinations of airway blood flow and cardiac output using a modification of the reference sample microsphere technique. Injection of bradykinin into the left ventricle increased airway blood flow in a dose-related manner. Pretreatment with the bradykinin B2 receptor antagonist, Hoe 140, completely abolished bradykinin-, but not histamine-induced vasodilation. A bradykinin B1 receptor agonist, [des-Arg9]bradykinin, did not affect airway blood flow. We also studied the effect of inhibitors of angiotensin-converting enzyme (captopril) and neutral endopeptidase (phosphoramidon) on bradykinin-induced vasodilation. Pretreatment with captopril, but not phosphoramidon, potentiated the bradykinin-induced vasodilation. However, the addition of phosphoramidon further potentiated the effect of captopril. We conclude that injection of bradykinin into the left ventricle produces a dose-related vasodilation in the airway microcirculation mediated via B2 receptors, an effect that is modulated primarily by angiotensin-converting enzyme and, to a lesser extent, by neutral endopeptidase.

Animals↗

PubMed1994

Leumedin NPC 15669 inhibits antigen-induced recruitment of inflammatory cells into the canine airways.

We studied the effects of NPC 15669, a member of a new class of anti-inflammatory drugs called leumedins, on chemotaxis of both human eosinophils and neutrophils and on Mac-1 receptor upregulation on stimulated eosinophils in vitro. Then, we examined the effect of NPC 15669 on antigen-induced eosinophil and neutrophil recruitment and subsequent airway hypersecretion (indicated by an increase in lysozyme concentration) in the allergic dog trachea in vivo. NPC 15669 inhibited eosinophil chemotaxis in vitro at a drug concentration of 10(-5) M (mean inhibition, 48.2%) without affecting Mac-1 receptor upregulation on stimulated eosinophils. NPC 15669 also inhibited neutrophil chemotaxis: at 10(-5) M, NPC 15669 inhibited neutrophil chemotaxis by a mean of 29.7%. In allergic dogs in vivo, NPC 15669 (10(-5) M) prevented antigen-induced recruitment of eosinophils and neutrophils and prevented the increase in elastase and lysozyme concentrations. We conclude that NPC 15669 is an effective inhibitor of antigen-induced leukocyte recruitment and elastase release and subsequent hypersecretion in airways.

Animals↗

PubMed1994

Neutral endopeptidase in the heart. Neutral endopeptidase inhibition prevents isoproterenol-induced myocardial hypoperfusion in rats by reducing bradykinin degradation.

Peptide mediators may play a role in the control of myocardial perfusion. We found immunohistochemical evidence of the peptide-degrading enzyme neutral endopeptidase (NEP) in cultured rat myocytes. Therefore, we examined the effect of an NEP inhibitor, phosphoramidon, on myocardial perfusion in rats after (1) stimulating sensory nerves with capsaicin and (2) inducing myocardial hypoperfusion with isoproterenol, with or without pretreatment with selective antagonists of the substance P (NK1) and bradykinin (B2) receptors. Three to five sequential determinations of myocardial blood flow were made in anesthetized rats by injecting 100,000 radionuclide-labeled microspheres suspended in 70% dextrose into the left ventricle. Phosphoramidon doubled coronary blood flow in response to a dose of capsaicin that was ineffective in the absence of the inhibitor. Isoproterenol (50 mg/kg IP) caused an immediate fall in blood pressure and coronary blood flow; after 20 minutes, flow had returned to normal but pressure was still subnormal. Administration of phosphoramidon reduced the recovery of blood pressure but greatly increased coronary blood flow. These changes were not altered by a substance P NK1 receptor blocker but were completely abolished by a selective bradykinin B2 receptor blocker. Our data indicate that (1) NEP is present in the rat myocardium, (2) sensory nerve-induced coronary vasodilation is markedly potentiated by NEP inhibition, (3) isoproterenol-induced myocardial hypoperfusion is prevented by NEP inhibition, and (4) this effect of NEP inhibition is due to reduced degradation of bradykinin.

Animals↗

PubMed1994

Role of neutral endopeptidase and kininase II on substance P-induced increase in nasal obstruction in patients with allergic rhinitis.

We studied the role of neutral endopeptidase (NEP) and kininase II (angiotensin-converting enzyme; ACE) in the modulation of exogenous substance P (SP)-induced nasal response in normal subjects and in patients with allergic rhinitis. We measured the nasal conductance in response to increasing doses of SP 2 h after oral administration of either placebo or the ACE inhibitor, cilazapril (5 mg), or the NEP inhibitor, acetorphan (300 mg), given in a randomized, double-blind, cross-over manner. We performed three separate studies: acetorphan versus placebo and cilazapril versus placebo, in normal subjects (n = 6 and n = 8, respectively), and acetorphan versus cilazapril versus placebo in patients with allergic rhinitis (n = 6). In normal as well as in rhinitic subjects, SP decreased nasal conductance in a dose-dependent fashion (p < 0.001). With placebo, the decrease in nasal conductance in normal subjects was similar to that in patients with allergic rhinitis (p > 0.5). In normal subjects, acetorphan potentiated the decrease in nasal conductance (p < 0.001), whereas cilazapril did not (p = 0.12). In patients with allergic rhinitis, the decrease in nasal conductance was potentiated by acetorphan (p < 0.001) and by cilazapril (p < 0.001). With acetorphan, the decrease in nasal conductance was not different in patients with allergic rhinitis and in normal subjects (p > 0.9). Conversely, with cilazapril, the nasal response to SP was greater in patients with allergic rhinitis than in normal subjects (p < 0.001).(ABSTRACT TRUNCATED AT 250 WORDS)

Administration, Intranasal↗

PubMed1994

Pseudomonas stimulates interleukin-8 mRNA expression selectively in airway epithelium, in gland ducts, and in recruited neutrophils.

Neutrophils may play important roles in chronic airway diseases. Pseudomonas is a common pathogen in some chronic airway diseases, and expression of the neutrophil chemoattractant interleukin-8 (IL-8) is induced by Pseudomonas in various cells in vitro. Here we examine the localization of IL-8 mRNA expression after incubating human and dog bronchi with Pseudomonas supernatant in vitro. To examine IL-8 expression in recruited neutrophils, we also superfused the dog bypassed tracheal segment with Pseudomonas supernatant in vivo and measured neutrophil number and IL-8 concentration in luminal fluid; simultaneously, we introduced Pseudomonas supernatant by catheter in a peripheral airway. After 6 h, we analyzed IL-8 mRNA expression and localization in removed tissue. Unincubated bronchi showed no IL-8 mRNA expression, but incubation with Pseudomonas supernatant in vitro resulted in IL-8 mRNA expression in surface epithelial, gland duct, and a subpopulation of serous gland cells. In vivo, introduction of Pseudomonas supernatant into dog trachea and peripheral airways caused IL-8 mRNA expression in epithelial and gland duct cells but also in the recruited neutrophils. Pseudomonas lipopolysaccharide alone was without effect in vitro and in vivo. We conclude that Pseudomonas products, but not lipopolysaccharide, stimulate IL-8 expression in airways and that this expression occurs primarily in surface epithelial and gland duct cells, thus bringing the chemoattractant to the bacterial site. Furthermore, IL-8 expression in recruited neutrophils provides a potential mechanism for positive feedback of this protective antibacterial response.

Adult↗

PubMed1994

Novel Pseudomonas product stimulates interleukin-8 production in airway epithelial cells in vitro.

Because high concentrations of IL-8 are found in the sputum of cystic fibrosis patients, we hypothesized that Pseudomonas aeruginosa (PA) induces the production of IL-8 in airway epithelial cells and in monocytes. Therefore, we incubated the supernatant from PA culture with human transformed bronchial epithelial cells (16-HBE) or with monocytes. The culture medium of 16-HBE cells that had been incubated with PA supernatant for 6 h had chemotactic activity that was inhibited by an antibody to human IL-8. The PA supernatant induced IL-8 production by primary bronchial epithelial cells, by 16-HBE cells, and by monocytes. After incubation with PA supernatant, 16-HBE cells showed a marked increase in the levels of IL-8 gene expression. The PA product responsible for IL-8 production resisted freezing, boiling, and proteolysis. This product was not lipid extractable and was present in a 1-kD filtrate. We conclude that a small molecular mass product of PA stimulates IL-8 production by 16-HBE cells and by monocytes, and that the chemotactic activity produced by 16-HBE cells after exposure to PA is due principally to IL-8.

Blotting, Northern↗