Eosinophils and mast cells in bronchoalveolar lavage in subjects with mild asthma. Relationship to bronchial hyperreactivity

We have performed bronchoalveolar lavage (BAL) on 17 subjects with mild atopic asthma (9 symptomatic, 8 asymptomatic) and 14 nonasthmatic control subjects (6 hay fever, 8 nonatopic). There was a significant increase in the percentage of mast cells in both groups of asthmatics although the counts were no different from those previously reported for a number of other respiratory diseases. Asthmatics with airway hyperreactivity (PC20 less than 4 mg/ml) had significant increases in spontaneous histamine release. There was a significant elevation in the eosinophil count and the concentration of major basic protein (MBP) in BAL fluid in the symptomatic asthmatics. Furthermore, there was a significant correlation between the amounts of MBP recovered and the percentage of eosinophils in the BAL. These changes were even more marked when asthmatics with airway hyperreactivity were compared with subjects with normoreactive airways. In addition, there was a significant increase in the percentage of epithelial cells in the hyperreactive asthmatics. There was an inverse correlation between the PC20 and the percentage of mast cells (p less than 0.01), eosinophils (p less than 0.05), and epithelial cells (p less than 0.05) and amount of MBP in BAL (p less than 0.01). This study supports the hypothesis that bronchial hyperresponsiveness is secondary to epithelial cell damage mediated through eosinophil-derived granule products.     

Antigen-coated sepharose beads induce airway eosinophilia and airway hyperresponsiveness in cynomolgus monkeys

A method of inducing sustained airway eosinophilia and airway hyperresponsiveness in primates has been developed. Our method utilizes a series of intratracheal instillations of Ascaris suum-coated sepharose 4B beads (3 x 10(5] administered once a week for four weeks. Five cynomolgus monkeys (Macaca fascicularis) demonstrating a naturally occurring skin and respiratory sensitivity to Ascaris suum extract were studied. Airway cell composition was measured by bronchoalveolar lavage (BAL), and airway responsiveness was determined as the bronchoconstrictor response to inhaled methacholine. Ascaris suum bead administration resulted in a transient increase in total cells recovered by BAL (2.4 +/- 0.4 to 8.7 +/- 2.5 x 10(5) cells/ml, p less than 0.05) and a selective increase in BAL eosinophils (17 +/- 6 to 916 +/- 158 x 10(3) cells/ml, p less than 0.05). Increases in airway responsiveness were concurrent with the increase in airway eosinophils. These observations show that airway eosinophilia is associated with airway hyperresponsiveness in primates. Furthermore, this new model is a novel experimental system in which the underlying mechanisms in the pathogenesis of airway hyperresponsiveness can be investigated.     

Role of potassium channels in bronchodilator responses in human airways.

The plasma membrane of airway smooth muscle contains a high density of K+ channels of various types that mainly regulate membrane potential. To examine whether these K+ channels are involved in bronchodilating mechanisms in human airways, relaxation concentration-response studies to isoproterenol, theophylline, and a K(+)-channel opener, lemakalim (BRL 38227), were obtained in the presence or absence of charybdotoxin (ChTX) (10 or 100 nM), an inhibitor of large conductance Ca(2+)-activated K+ channels (KCa) in smooth muscle. The effects of other potassium channel blockers, apamin (0.1 microM, a small-conductance KCa blocker) and BRL 31660 (10 microM, an ATP-sensitive K(+)-channel blocker) on isoproterenol-induced bronchodilation were also examined. All relaxation studies were performed on spontaneous tone and in the presence of 1 microM indomethacin. ChTX produced a dose-dependent significant rightward shift in the isoproterenol relaxation response curves without changing maximum relaxation; geometric mean values of EC50 were 4.6 nM without and 19 nM with 10 nM ChTX (n = 7, p less than 0.005), and 3.4 nM without and 41 nM with 100 nM ChTX (n = 4, p less than 0.05), respectively. The theophylline relaxation responses were inhibited to a lesser extent by ChTX (10 nM) (ED50 of 32 microM without and 71 microM with ChTX, n = 7, p less than 0.05), whereas lemakalim-induced relaxation response was not affected. Other K(+)-channel blockers, apamin and BRL31660, failed to affect isoproterenol-induced bronchodilation. These results suggest that ChTX-sensitive K+ channels are involved in bronchodilation induced by beta-agonists and theophylline in human airways.     

Large and small airway responses to bronchoconstrictors in the guinea pig and ferret

In the isolated, perfused lung lobe of the ferret we evaluated the bronchoconstrictor response of its airways to methacholine and histamine, pharmacologic agents associated with the asthmatic state. The bronchus of excised lobes was cannulated and needle scarifications were made on the pleural surface to allow perfusate to exit. Lung airways were perfused at constant flow with equilibrated 95% O2/5% CO2, warmed Krebs-Ringers solution. Perfusion pressure was measured as a gauge of airway resistance. A concentration-dependent smooth muscle contraction of the ferret lung lobes was observed to methacholine and histamine. The ED50's of methacholine and histamine were 6.41 x 10(-6) M +/- 1.38 x 10(-6) (SEM) and 6.41 x 10(-6) M +/- 1.38 x 10(-6) (SEM) and 2.39 x 10(-6) M +/- 0.53 x 10(-6) (SEM), respectively. The maximum level of bronchoconstriction developed in the ferret (2.42 mmHg/ml/min +/- 0.28 SEM (resistance units] in response to methacholine, was six times greater than that found for histamine (0.42 mmHg/ml/min +/- 0.05 SEM). Responses to both agonists were less pronounced in the ferret lung preparation than those in a similar lung preparation of guinea pig. Compliance changes in both animals were also evaluated. The ferret did not demonstrate a compliance change in response to histamine as was seen for methacholine, suggesting that resistance changes precede compliance changes, or that the ferret airways are particularly resistant to histamine. Despite a lesser contractile response, the ferret has the advantage of a relatively large lung and long trachea that allow study in several preparations obtained from a single animal. It should prove a useful animal model for study of pulmonary pharmacology.     

Allergen-induced airway reactions in atopic asthmatics correlate with allergen-specific IL-5 response by BAL cells

Abstract Allergen-specific cytokine responses in the airways are thought to play a critical role in the pathogenesis of atopic asthma. This study examined whether there is a quantitative difference in bronchoalveolar lavage (BAL) cell allergen-induced IL-5 production between atopic subjects with and without asthma which may relate to a difference in airway response induced by allergen exposure. Twelve atopic asthmatics (AA), nine atopic non-asthmatics (AN) and 10 normal controls (N) underwent inhalation challenge with house dust mite allergen (HDM) extract. AA differed from AN in having late airway reactions (LAR) after HDM inhalation ( P < 0.01), which correlated with an increased percentage of BAL eosinophils and increased BAL cell IL-5 production after in vivo or in vitro HDM challenge for the AA group ( P < 0.01). IL-5 production by PBMC from both atopic groups was elevated with HDM stimulation in vitro , but AA again had a higher level under baseline conditions than AN ( P < 0.02). Furthermore, there was a greater effect of BAL fluid from AA on ECP release by eosinophils compared to that for AN ( P < 0.01). These findings suggest that increased IL-5 production in atopic asthmatic airways contributes to the increased physiological response to allergen inhalation, by modulating local eosinophil recruitment and activation.     

Reduced eosinophil pro‐fibrogenic effect in severe childhood asthma compared to mild disease: An effect of corticosteroids?

Eosinophils play an important role in inflammation and probably in airway remodeling in asthma. We previously demonstrated that eosinophils from atopic subjects display pro-fibrogenic properties towards lung fibroblasts partially by preformed transforming growth factor-beta (TGF-beta). We hypothesized that the pro-fibrogenic potential of eosinophils is increased in children with life-threatening asthma (LTA). Six children with atopic LTA clinically well-controlled by inhaled corticosteroids (ICS) and 5 children with atopic mild asthma (MA) treated only with inhaled beta(2)-agonists were investigated. The effects of their peripheral blood eosinophils on fibroblast proliferation and lattice contraction were investigated. In addition, TGF-beta(1) and IL-6 eosinophil content were also evaluated. Unexpectedly, eosinophils from LTA increased fibroblast proliferation (5.4-fold) and gel contraction (1.1-fold) significantly less than those from MA. TGF-beta(1) but not IL-6 eosinophil content in LTA was significantly lower than that in MA (2.7-fold). In vitro, addition of dexamethasone on eosinophils stimulated by mast cells resulted in a marked decrease in their TGF-beta(1) content by 1.6-fold. In conclusion, eosinophils from children with ICS-treated LTA displayed significantly less pro-fibrogenic properties than those from MA treated only with beta(2)-agonists. Our data suggest that the pro-fibrogenic effect of eosinophils might be influenced by treatment with ICS in childhood asthma.     

Generation and metabolism of 5-lipoxygenase pathway leukotrienes by human eosinophils: predominant production of leukotriene C4.

5-Lipoxygenase pathway-derived products of arachidonic acid released by human eosinophils activated in vitro have been measured by using radioimmunoassays specific for leukotriene B4 (LTB4) and for sulfidopeptide leukotrienes including leukotriene C4 (LTC4). Eosinophil-enriched leukocytes (mean, 85% eosinophils) from five hypereosinophilic donors activated with 5.0 microM ionophore A23187 for 15 min at 37 degrees C in the presence of 50 mM L-serine released 69 +/- 28 and 1.5 +/- 0.8 (mean +/- SEM) ng of LTC4 and LTB4, respectively, per 10(6) cells; ratios of LTC4 to LTB4 ranged from 16 to 149. Eosinophils stimulated with ionophore (2.5 microM) or phorbol myristate acetate (1 microgram per ml) metabolized exogenously added LTC4 to products that coeluted on reverse-phase high-performance liquid chromatography with synthetic S-diastereoisomeric LTC4 sulfoxides and 6-trans-LTB4 diastereoisomers, and this metabolic inactivation was inhibited by L-serine or catalase. Ionophore-activated eosinophils purified from three normal donors also preferentially generated LTC4 (38 +/- 3 ng per 10(6) cells) relative to LTB4 (6.0 +/- 3.1 ng per 10(6) cells), whereas neutrophils from the same donors released LTB4 (48 +/- 21 ng per 10(6) cells) in a greater than 7-fold excess to LTC4. The predominant production by human eosinophils of LTC4 with its potent smooth muscle spasmogenic and vasoactive properties may contribute to the pathobiology of allergic and other diseases associated with eosinophilia.     

The effects of 5-HT on cholinergic contraction in human airways in vitro.

Inhaled 5-hydroxytryptamine (5-HT) causes bronchoconstriction in asthmatics, and 5-HT plasma levels are elevated in asthma. Electrical field stimulation (EFS) of human airways, in vitro, evokes cholinergic contraction mediated by the release of acetylcholine (Ach) from postganglionic cholinergic nerves. The present study investigates whether selective 5-HT agonists and antagonists can modulate EFS-induced cholinergic contraction in human airways in vitro. Human airways, obtained from resections for bronchial carcinoma or organ transplant donors, were suspended under 2-g tension, between two platinum wire electrodes, in carbogenated Krebs solution at 37 degrees C and EFS was applied (1-32 Hz, 50 V, 0.5 ms, 15 s every 4 min) to elicit cholinergic contractions. 5-HT (10 microM-0.3 mM) produced frequency- and concentration-dependent facilitation of cholinergic contraction, but did not displace the concentration/response curve to Ach. Tropisetron (1 microM), a 5-HT3 and 5-HT4 antagonist, completely blocked the facilitatory effect of 5-HT (100 microM), whereas both ondansetron (1 microM) and GR 125478D (1 microM), a selective 5-HT3 and 5-HT4 antagonist, respectively, also attenuated the 5-HT-induced enhancement of cholinergic contraction. This facilitatory effect of 5-HT was partially mimicked by both selective 5-HT3 (2-methyl-5-HT) and 5-HT4 (RS 67333 and 5-methoxytryptamine) agonists. Fluoxetine (10 microM), a 5-HT uptake inhibitor, had no effect on the 5-HT (10-100 microm) induced potentiation of cholinergic contraction. These findings suggest that 5-HT facilitates cholinergic contraction in human airways in vitro through stimulation of both prejunctional 5-HT3 and 5-HT4 receptors. This may implicate a role of 5-HT in asthma.     

The bronchoconstrictor properties of platelet-activating factor in humans

Platelet-activating factor (PAF) is an inflammatory mediator that causes bronchial smooth muscle contraction in vitro and in vivo in experimental animals. To characterize the effect of PAF on human airways, 6 normal subjects and 6 subjects with mild asthma inhaled PAF using a standard bronchoprovocation protocol and nebulizer concentrations ranging from 0.1 to 1000 micrograms/ml. Aerosolized PAF produced bronchoconstriction in 5 of 6 normal and 3 of 6 asthmatic subjects as defined by at least a 35% decrease in specific airway conductance (SGaw). However, in these same subjects, flow rates measured at 30% of vital capacity from a partial forced expiratory maneuver (V30P) did not decrease at least 30% nor did the FEV1 decrease by 20%. The 8 PAF responders were 5 to 836 times more sensitive to PAF than to methacholine when SGaw was used to assess the airway response. The relative airway sensitivity of the PAF nonresponders could not be assessed. Normal and asthmatic subjects could not be differentiated by their airway response to PAF, and there were no clinical features that differentiated PAF responders from nonresponders. The maximal airway response to PAF occurred within 2 to 3 min and lasted 15 to 45 min. There were no late reactions. Both normal (p less than 0.01) and asthmatic (p less than 0.05) subjects exhibited tachyphylaxis to PAF. Finally, PAF sensitized the airways of all normal subjects to methacholine, including the one PAF nonresponder (p less than 0.02), but it did not sensitize the airways of the asthmatic subjects.(ABSTRACT TRUNCATED AT 250 WORDS)     

The effect of inhaled vasoactive intestinal peptide on bronchial reactivity to histamine in humans

Nonadrenergic, noncholinergic nerves are the predominant inhibitory nervous pathway in human airway smooth muscle, and there is evidence in animals that the major neurotransmitter of this system is vasoactive intestinal peptide (VIP). We have investigated the effect of VIP on bronchomotor tone and bronchial responsiveness to inhaled histamine in 6 atopic asthmatic subjects. The VIP was given by inhalation to avoid any indirect effects on the airways that might arise from the potent cardiovascular actions of this peptide when given systemically. The VIP (100 micrograms) was compared with control solution (diluent: 1% human serum albumin in 2 ml 0.9% saline) and with beta 2-agonist (salbutamol, 200 micrograms) given double blind in random order on separate days. Specific airway conductance (SGaw) did not change after control or VIP inhalations, but it significantly increased after salbutamol inhalation. The provocation concentration of histamine causing a 35% fall in SGaw (PC35) did not change after control inhalation, but significantly increased after VIP (from 2.18 +/- 1.04 to 5.00 +/- 2.31 mg/ml histamine, mean +/- SE; p less than 0.05), and after salbutamol (from 1.71 +/- 0.83 to 15.6 +/- 4.2 mg/ml, p less than 0.01), the increase after salbutamol being significantly greater than after VIP. No changes in heart rate or blood pressure were found after any inhalation. We conclude that VIP protects against histamine-induced bronchoconstriction in human airways in vivo, and therefore has the capacity to be the neurotransmitter of nonadrenergic, noncholinergic inhibitory nerves in human airway smooth muscle.     

Aggregations of lymphoid cells in the airways of nonsmokers, smokers, and subjects with asthma

Persistent airway inflammation is present in cases with asthma and in smokers with airflow obstruction. Isolated aggregations of lymphoid cells (IALC) may be sites of localized inflammatory cell activation. Their distribution and characteristics in cartilaginous airways were assessed in postmortem tissue from nonsmokers (n=10), smokers (n=9), and cases of nonfatal (n=10) and fatal asthma (n=10). IALC were present in 70-100% of cases, were more often in proximal than distal airways, and 80% were confined to the outer airway wall. IALC with area greater than 0.1 mm2 were more frequent in both asthma groups (p<0.001). Airways with IALC had increased airway dimensions and greater numbers of eosinophils and lymphomononuclear cells. Within IALC, T and B lymphocytes were segregated and comprised more than 90% of all cells. Proliferating, apoptotic, and antigen-presenting cells (Rel B+ and HLA-DR+) were less than 5%, 30-40%, and less than 1% of all cells, respectively, and were similar in each case group. Vascular structures were increased (p < 0.01) in cases of fatal asthma. These findings show that, even in nonsmoking cases and cases without asthma, IALC are common, show cellular organization, and are associated with airway wall inflammation and remodeling. It remains to be determined if IALC contribute to or result from persistent airway inflammation in asthma.     

Mechanisms of contraction induced by human leukocytes in normal and atherosclerotic arteries

Activation of leukocytes results in the release of a variety of vasoactive substances that may modulate vascular tone. We studied the effect of human polymorphonuclear (PMN) and mononuclear (MONO) leukocytes on quiescent femoral arteries in vitro. Arteries were obtained from normal and atherosclerotic cynomolgus monkeys. In normal arteries, stimulation of PMNs (3 and 5 x 10(6) cells/ml) with either thrombin (5 units/ml) or complement C5a (0.5 micrograms/ml) resulted in endothelium-independent contraction (approximately 25% of maximum contraction with 80 mM KCl). Vasocontraction was augmented in the presence of superoxide dismutase (150 units/ml) and was significantly impaired in the presence of the hydroxyl radical scavengers mannitol (20 mM) and deferoxamine (1 mM). Catalase (1,200 units/ml) or L-alanine (20 mM) did not modify this effect of PMNs. In contrast to PMNs, vasocontraction in response to MONOs was not altered by the addition of radical scavengers. Pretreatment of PMNs and MONOs with indomethacin (10 microM) or nordihydroguaiaretic acid (20 microM) did not influence vascular responses. Supernatant of thrombin-stimulated PMNs and MONOs also produced vasocontraction (approximately two thirds of the effect of intact cells). This vasocontractor factor (or factors) was heat stable (30 minutes, 95 degrees C) and had a molecular weight less than 1,000 as determined by ultrafiltration. Stimulation of MONOs or PMNs (3 and 5 x 10(6) cells/ml) produced a similar response in normal arteries. In contrast, the constrictor response in atherosclerotic arteries to MONOs (5 x 10(6) cells/ml) was significantly greater than to PMNs. We conclude that stimulated human PMNs and MONOs contract arteries in vitro by release of at least two factors. One factor appears to be heat stable, with a molecular weight less than 1,000. The vascular response to PMNs, but not to MONOs, appears to involve the generation of hydroxyl radicals. The response to MONOs is greater than the response to PMNs in atherosclerotic, but not in normal, arteries.     

Eotaxin expression after segmental allergen challenge in subjects with atopic asthma

Expression of pulmonary eotaxin protein and mRNA was determined in six subjects with atopic asthma and five nonatopic normal subjects. Levels of eotaxin expression and eosinophil mobilization were compared before and after segmental allergen challenge in subjects with atopic asthma. In the absence of allergen challenge, we found significantly higher levels of eotaxin in the bronchoalveolar lavage (BAL) fluid of subjects with asthma than in that of normal subjects (25 +/- 3 versus 15 +/- 2 pg/ml, p < 0.05). BAL eotaxin levels increased after segmental allergen challenge in all six subjects with atopic asthma tested, with a mean increase from 22 +/- 4 to 53 +/- 10 pg/ml (p = 0.013). Segmental allergen challenge was associated with a significant increase in the percentage of BAL macrophages and eosinophils that were immunopositive for eotaxin. Eotaxin mRNA was detectable by northern analysis in BAL cells exclusively from allergen-challenged segments. Allergen- induced increases in eotaxin levels were strongly associated with increases in BAL eosinophil recovery (r(2) = 0.88, p = 0.0036). Segmental allergen challenge also increased eotaxin expression in airway epithelial and endothelial cells obtained by endobronchial biopsy. These findings demonstrate, for the first time, that the airways of subjects with allergic asthma respond to allergen by increasing eotaxin expression. The tissue loci of eotaxin expression, the levels of eotaxin recovered in BAL fluid, and the association of eotaxin levels with eosinophil mobilization suggest either that eotaxin plays a mechanistic role in allergen-induced airway eosinophilia or that it serves as a biomarker for the causal mechanisms.     

Mediator release in an isolated airway segment in subjects with asthma

To determine if mediator release would occur in the airways of human subjects after exposure to a hyperosmolar stimulus, we challenged isolated airway segments in vivo with 900 mosmol sodium chloride using a specially designed double-balloon catheter. In order to determine if differences in mediator concentrations correlated with airway responsiveness or with atopy, we studied 3 separate groups: 6 atopic, asthmatic subjects; 6 atopic, nonasthmatic subjects; and 6 nonatopic, nonasthmatic normal subjects. In addition, to determine if the presence of the catheter itself was a stimulus, we studied 6 atopic, asthmatic subjects after exposure to isotonic sodium chloride alone (sham exposure). Lavage specimens were assayed for PGD2, PGF2 alpha, PGE2, TxB2, LTC4, and LTB4 by radioimmunoassay and for histamine by the modified single isotope enzymatic assay. The histamine concentration of the baseline lavage samples (bronchoalveolar lavage and isolated airway segment lavage) for the subjects with asthma were significantly greater than for the atopic or normal subjects (p less than 0.05). There was a significant negative correlation between histamine concentration in the lavage samples and the airway responsiveness of the subjects (r = -0.53, p less than 0.0001). There was a marked correlation among the concentrations of histamine, PGD2, PGF2 alpha, and TxB2 in all the lavage fluids for the subjects with asthma (p less than 0.03 for all comparisons and p less than 0.0001 for overall concordance). As a result of hyperosmolar challenge, there was a significant increase in the concentration of histamine, PGD2, and PGF2 alpha in the subjects with asthma.(ABSTRACT TRUNCATED AT 250 WORDS)     

Airways inflammation in nocturnal asthma

Nocturnal asthma is a frequent problem, but the mechanism is unclear. We investigated the possibility that airways inflammation occurred during the night. Bronchoalveolar lavage fluid was analyzed in asthmatic patients with (n = 7) and without nocturnal asthma (n = 7) at 1600 and 0400 h. The nocturnal asthma group had an increase in the total leukocyte count (24.0 +/- 7.0 to 41.1 +/- 9.9 x 10(4) cells/ml, p less than 0.05), neutrophils (1.1 +/- 0.6 to 3.7 +/- 1.5 x 10(4) cells/ml, p less than 0.05), and eosinophils (0.5 +/- 0.1 to 1.7 +/- 0.7 x 10(4) cells/ml, p less than 0.05) from 1600 to 0400 h. Cellular components for the non-nocturnal asthma group did not change. Between groups, the 1600-h cells were similar. At 0400 h the nocturnal asthma group had significantly higher total leukocyte, neutrophil, eosinophil, lymphocyte, and epithelial cell counts. For all subjects, the overnight fall in peak expiratory flow rates was correlated to the change in neutrophils (r = 0.54, p less than 0.05) and eosinophils (r = 0.77, p less than 0.05). We conclude that the nocturnal worsening of asthma has an associated cellular inflammatory response that is not seen in patients without overnight decrements in lung function. This inflammatory response together with epithelial damage may be important factors in the etiology of nocturnal asthma.     

The effects of inhaled budesonide on circulating eosinophil progenitors and their expression of cytokines after allergen challenge in subjects with atopic asthma

Allergen inhalation by dual responder subjects with atopic asthma is associated with an increase in circulating eosinophil/basophil colony-forming units (Eo/B CFU) and granulocyte-macrophage colony- stimulating factor (GM-CSF) immunolocalization in Eo/B colony cells grown in vitro. The current study examined the effect of the inhaled corticosteroid, budesonide, on the number of allergen- induced circulating eosinophils and Eo/B CFU, and immunolocalization of GM-CSF and interleukin-5 (IL-5) in Eo/B colony cells grown in vitro. Sixteen subjects with mild atopic asthma were treated for either 7 or 8 d with 200 microg inhaled budesonide or placebo twice a day. Peripheral blood was collected before and 24 h after allergen inhalation challenge and nonadherent mononuclear cells (NAMC) were grown in methylcellulose culture. Eo/B CFU were enumerated after 14 d in culture, and prepared on slides for immunocytochemistry. Budesonide attenuated the allergen-induced increase in circulating eosinophils (4.0 +/- 0.4 x 10(5)/ml versus 6.5 +/- 0.7 x 10(5)/ml, p = 0.0001), circulating Eo/B CFU (12.4 +/- 2.3/10(6) NAMC versus 18.8 +/- 4.6/10(6) NAMC, p = 0.05), and immunolocalization of GM-CSF in Eo/B colony cells (11.8 +/- 1.9% positive versus 18.0 +/- 2.2%, p = 0.01) but not immunolocalization of IL-5 (7.9 +/- 1.4% versus 4.5 +/- 0.6%, p > 0.05). Inhaled budesonide attenuated the number of allergen-induced circulating eosinophils and their progenitors grown in the presence of GM-CSF, which may partially be a result of regulating eosinophil progenitor expression of the autocrine growth factor GM-CSF.     

Central and peripheral airways as determinants of ventilatory function in patients with chronic bronchitis, emphysema, and bronchial asthma

We studied central and peripheral airways as determinants of ventilatory function in patients with chronic bronchitis (CB), bronchial asthma (BA), and emphysema (CPE), which were identified using the selective alveolobronchogram (SAB) (see reference 14). First, the relationship between SAB and morphologic findings in the airway was examined in 16 autopsy lungs. The irregularity indices of both central (C-II) and peripheral airways (P-II), obtained from SAB, showed a significant correlation with pathologic abnormalities in both airways (p less than 0.01). Second, SAB were obtained in 38 CB, 25 BA, and 62 CPE patients in whom pulmonary function tests were performed. In CB, C-II were significantly correlated with P-II (p less than 0.001). In CB, inspiratory lung resistance (RL) was significantly correlated with P-II (p less than 0.001) and with C-II (p less than 0.01), and FEV/VC% was significantly correlated with P-II (p less than 0.0001) but not with C-II. In BA and CPE, little correlation was observed between any SAB parameter and RL or FEV/VC%. We conclude that the present SAB parameters represent morphometric abnormalities of the central and peripheral airways, and that in CB, peripheral airway abnormalities correlated well with chronic airway obstruction.     

The effect of phosphoramidon and epithelium removal on toluene diisocyanate-induced contractions in guinea-pig bronchi.

To evaluate the role of airway neutral endopeptidase 24.11 (NEP) and epithelium removal in the contraction of airway smooth muscle in response to toluene diisocyanate (TDI), we studied the effects of the NEP inhibitor, phosphoramidon, on TDI-induced contractions of guinea-pig bronchial rings with intact epithelium and without epithelium. In preparations with intact epithelium, phosphoramidon (10 microM) potentiated the contractile response to TDI (0.3 mM) (mean +/- SEM, 23.7 +/- 2.5% versus 67.9 +/- 10.3%, p less than 0.01). Phosphoramidon also increased TDI-induced contractions in tissues without epithelium (36.9 +/- 4.9% versus 52.5 +/- 7.1%, p less than 0.05). Removal of the epithelium increased the contractile response to TDI (23.7 +/- 2.5% versus 36.9 +/- 4.9%, p less than 0.05). These results demonstrate the response to TDI is increased in epithelium-free compared to intact bronchi and that NEP 24.11 modulates the effects of endogenously released tachykinins by TDI at all of the sites where NEP is found in the airways.     

The distribution of myeloperoxidase, eosinophil cationic protein, albumin and urea in sequential bronchoalveolar lavage.

The distribution of myeloperoxidase (MPO) and eosinophil cationic protein (ECP), secreted from activated neutrophils and eosinophils, was estimated in bronchoalveolar lavage fluid in a sequential lavage study performed on 12 healthy subjects. Four 50 ml aliquots were sequentially injected into the right middle lobe and immediately aspirated. Recent studies, using radiological methods, have revealed proximal airway distribution of the first infused lavage aliquot, and more peripheral distribution of the following ones. We found significantly higher concentrations of MPO (p less than 0.001) and ECP (p less than 0.001) in the first aspirated aliquots as compared to the following three. These findings are compatible with the concept that these substances are, to a substantial part, distributed to the surface of the proximal airways. In contrast, the sequential recovery of albumin and urea showed a homogeneous recovery pattern. The findings were compatible with those of a small series of sixteen 10 ml lavage aliquots, sequentially infused and aspirated, also indicating a continuous diffusion of these small molecules through the lung membranes into the lavage fluid during the lavage process. We conclude that the difference in recovery pattern and distribution on the bronchial surface makes albumin and urea unsuitable as denominators in ratios to MPO and ECP, for the estimation of quantitative local concentration in epithelial lining fluid.