ovalbumin and Constriction--Pathologic

Hepatic venoconstriction occurs in rat anaphylactic hypotension. However, the exact venoconstrictive site remains unknown, and we therefore attempted to determine its location by using hepatic venography and histology. Anaphylaxis was induced in anesthetized Sprague-Dawley rats by i.v. administration of ovalbumin antigen. Venography of the portal vein (n = 8) was obtained at baseline and maximal hepatic venoconstriction. We separately examined photomicrographs of the liver sections. Along with systemic hypotension, portal venous pressure increased to a peak of 28 ± 3 cm- H2O at 2 min after antigen injection. Post-antigen portal venography revealed that 40% of portal venuls (76 vessels/total 188 vessels) with diameters from 160 to 300 μm were not visualized, suggesting that stenosis or obliteration occurred distally. The corresponding upstream portal vessels exhibited markedly bulging. Stenosis was also observed in some portal branches with diameters from 180 to 420 μm (9%; 17 vessels/total 188 vessels). Light microscopically, most portal venules with an estimated baseline diameter less than 110 μm showed stenosis, but statistically significant stenosis was found in those with baseline diameters of 20-70 μm. In conclusion, anaphylactic hepatic venoconstriction occurs over a wide range of portal veins with diameters less than 420 μm, and occurs markedly in portal venules with diameters less than 70 μm in anesthetized rats.

Topics: Anaphylaxis; Anesthesia; Animals; Constriction, Pathologic; Liver; Male; Ovalbumin; Phlebography; Portal Vein; Rats

One feature of allergic asthma, the EAR (early allergic reaction), is not present in the commonly used mouse models. We therefore investigated the mediators involved in EAR in a guinea-pig in vivo model of allergic airway inflammation. Animals were sensitized using a single OVA (ovalbumin)/alum injection and challenged with aerosolized OVA on day 14. On day 15, airway resistance was assessed after challenge with OVA or MCh (methacholine) using the forced oscillation technique, and lung tissue was prepared for histology. The contribution of mast cell mediators was investigated using inhibitors of the main mast cell mediators [histamine (pyrilamine) and CysLTs (cysteinyl-leukotrienes) (montelukast) and prostanoids (indomethacin)]. OVA-sensitized and challenged animals demonstrated AHR (airway hyper-responsiveness) to MCh, and lung tissue eosinophilic inflammation. Antigen challenge induced a strong EAR in the sensitized animals. Treatment with a single compound, or indomethacin together with pyrilamine or montelukast, did not reduce the antigen-induced airway resistance. In contrast, dual treatment with pyrilamine together with montelukast, or triple inhibitor treatment, attenuated approximately 70% of the EAR. We conclude that, as in humans, the guinea-pig allergic inflammation model exhibits both EAR and AHR, supporting its suitability for in vivo identification of mast cell mediators that contribute to the development of asthma. Moreover, the known mast cell mediators histamine and leukotrienes were major contributors of the EAR. The data also lend further support to the concept that combination therapy with selective inhibitors of key mediators could improve asthma management.

Topics: Acetates; Animals; Asthma; Bronchial Hyperreactivity; Constriction, Pathologic; Cyclopropanes; Disease Models, Animal; Guinea Pigs; Histamine Antagonists; Hypersensitivity; Indomethacin; Leukotriene Antagonists; Lung; Mast Cells; Ovalbumin; Prostaglandin Antagonists; Pyrilamine; Quinolines; Sulfides

Nerve growth factor (NGF) contributes to airway inflammation and bronchoconstriction in allergic asthma. The Src homology 2beta/serine/threonine kinase (SH2-Bbeta/Akt) pathway is one of the avenues through which NGF regulates the biological activity of pheochromocytoma (PC)12 cells. It has also been reported that NGF upregulates the expression of SH2-Bbeta in the lung tissue of asthmatic mice. The present study investigated the effects of NGF and SH2-Bbeta on Akt activation during allergic airway challenge.. BALB/c mice were sensitized and challenged with ovalbumin. The effects of NGF and SH2-Bbeta on Akt in allergic airway challenge were assessed by intravenously administering anti-NGF antibody or a mutant of SH2-Bbeta (R555E) to these mice. Pulmonary histological changes were then assessed and the inflammatory cells in the BAL fluid (BALF) were counted. Additionally, phosphorylated Akt (p-Akt) expression was determined by fluorescence microscopy, western blotting and quantitative RT-PCR. Airway resistance was also measured using closed-type body plethysmography.. We observed p-Akt overexpression in the lungs after allergen challenge by fluorescence microscopy, Western blotting and RT-PCR, as compared with the control. However, after treatment with anti-NGF or R555E, p-Akt levels and allergen-induced airway inflammation were reduced in comparison with those of allergen-challenged mice. Anti-NGF and R555E also decreased airway hyperresponsiveness caused by allergen challenge in response to methacholine (MCH).. These results suggest that SH2-Bbeta regulation of Akt partly participates in the NGF-mediated development of allergic airway challenge.

Topics: Adaptor Proteins, Signal Transducing; Airway Resistance; Animals; Asthma; Bronchial Hyperreactivity; Constriction, Pathologic; Female; Methacholine Chloride; Mice; Mice, Inbred BALB C; Nerve Growth Factor; Ovalbumin; Proto-Oncogene Proteins c-akt

The role of small airways in the immediate allergic response is largely unknown. We therefore used the model of precision-cut lung slices (PCLS) in combination with quantitative videomicroscopy to study the early allergic response to allergen in airways ranging from 50 to 900 microm. After PCLS from untreated Wistar rats had been passively sensitized for 16 h with serum from sensitized Brown Norway rats, exposure to 0.1% ovalbumin resulted in an immediate allergic response. Both extent (r = 0.74, p < 0.0001) and velocity (r = 0.49, p < 0.0001) of the allergen-induced bronchoconstriction increased with decreasing airway size. In addition, we observed that smaller airways not only contracted stronger and quicker, but that they also relaxed faster, suggesting that smaller airways are more reactive in principle. The allergen-induced bronchoconstriction in PCLS was prevented by the serotonin receptor antagonist ketanserin (IC(50) 6 nM), but not by antagonists directed against histamine, acetylcholine, PAF, or endothelin receptors, or by cyclooxygenase or lipoxygenase inhibitors. Like allergen, serotonin provoked responses that were stronger in smaller airways. These findings suggest that the immediate allergic response in rat PCLS depends largely on serotonin and that this response can occur in nearly all airway generations, but is most pronounced in the smallest airways, that is, the terminal bronchioles.

Topics: Allergens; Animals; Asthma; Bronchial Diseases; Constriction, Pathologic; Disease Models, Animal; Drug Evaluation, Preclinical; Female; Hypersensitivity, Immediate; Immunization; Ketanserin; Microscopy, Video; Ovalbumin; Rats; Rats, Wistar; Serotonin; Serotonin Antagonists

We have recently demonstrated that tissue resistance increases during the early response (ER) to antigen challenge in sensitized Brown-Norway rats. The purpose of the present study was to investigate the role of the potential ER mediators 5-hydroxytryptamine (5-HT) and leukotriene D4 (LTD4) in the airway and tissue response. We sensitized the rats with ovalbumin (OA) and performed experiments on anesthetized, open-chested, mechanically ventilated [breathing frequency = 1 Hz, tidal volume = 12 ml/kg, positive end-expiratory pressure (PEEP) = 3 cmH2O] animals. We affixed alveolar capsules to the lungs to measure alveolar pressure and calculated the resistance of lung (RL), tissue (Rti), and airway (Raw). To assess the effects of LTD4 and 5-HT, we administered the antagonists methysergide (5-HT antagonist) and MK-571 (LTD4 antagonist) before challenge. To assess lung morphometry during the ER, the lungs of four animals from each group were frozen with liquid nitrogen (PEEP = 3 cmH2O). Airway constriction was assessed by measuring the ratio of the airway lumen to the ideally relaxed airway (Abm/A*bm). Tissue distortion was assessed by measuring the mean linear intercept between alveolar walls (Lm), an atelectasis index (ATI) derived by calculating the ratio of tissue to air space, and SD of the two (SD-Lm and SD-ATI). In all animals receiving OA but no antagonists, an ER was seen (RL, Rti, and Raw = 180.7 +/- 6.1, 155.4 +/- 8.2, and 223.1 +/- 14.0% of baseline, respectively). Methysergide significantly inhibited the ER (RL, Rti, and Raw = 117.0 +/- 5.9, 101.2 +/- 1.6, 133.7 +/- 10.2%, respectively), whereas MK-571 partially reduced the ER (RL, Rti, and Raw = 144.2 +/- 5.6, 132.9 +/- 5.7, and 155.5 +/- 9.2%, respectively). Abm/A*bm was significantly decreased, and SD-Lm and SD-ATI were significantly increased in animals receiving OA alone and in those receiving MK-571 before OA challenge. These data suggest that alterations in both airways and tissues contribute to the ER and that 5-HT and, to a lesser degree, LTD4 are important mediators of the ER in this rat model of extrinsic asthma.

Topics: Air Pressure; Airway Resistance; Animals; Basement Membrane; Constriction, Pathologic; Elasticity; Leukotriene D4; Lung; Ovalbumin; Rats; Rats, Inbred BN; Respiratory Function Tests; Respiratory Hypersensitivity; Serotonin; Serotonin Antagonists

The ovalbumin (OA)-sensitized Brown Norway rat (BN) demonstrates early-response (ER) and late-response (LR) allergic bronchoconstriction. To determine whether these responses could be replicated in vitro, we studied lung explants from 8-wk-old male BN rats (wt: 239 +/- 28 g), of which 19 were sensitized to OA (test) and 16 served as controls. Two weeks after sensitization, the animals' lungs were removed, filled with a 1% (wt/vol) agarose-containing solution at 37 degrees C, and cooled to 4 degrees C. Transverse slices (0.5 to 1.0 mm thick) were cut and cultured overnight. Airways were visualized with an inverted microscope and baseline images were obtained with a video camera. To study the ER, 40 airways from 15 test rats and 29 airways from 10 control rats were challenged with 2 micrograms OA and imaged each minute for 10 min. To study the LR, 40 airways from 12 test rats and 44 airways from 12 control rats were challenged with 2 micrograms OA and imaged each hour for 8 h. The maximal response (MR) for each airway was defined as the percent of airway closure. The ER and LR were both defined as an MR > or = mean + 2 SD of the controls. An ER occurred in 38 of 40 test and 2 of 29 control airways (mean MR: 42 +/- 24% versus 4 +/- 3%, p < 0.001), and was completely blocked by methysergide pretreatment in 13 airways.(ABSTRACT TRUNCATED AT 250 WORDS)

Topics: Airway Resistance; Animals; Asthma; Bronchial Provocation Tests; Bronchodilator Agents; Constriction, Pathologic; Disease Models, Animal; Drug Hypersensitivity; Hypersensitivity, Delayed; Hypersensitivity, Immediate; Immunoglobulin E; In Vitro Techniques; Leukotriene D4; Male; Methysergide; Ovalbumin; Premedication; Propionates; Quinolines; Rats; Serotonin; Time Factors

Effects of U-67590A, an analogue of methylprednisolone, on antigen-induced bronchoconstriction expressed as ventilation overflow were examined in ovalbumin-sensitized guinea pigs. When administered intravenously 17-18 hr before the challenge with antigen, U-67590A at doses of 10 and 30 mg/kg caused dose-dependent inhibition of increased ventilation overflow immediately after challenge. Death due to anaphylactic shock was markedly reduced by U-67590A. At 10 mg/kg (i.v.), U-67590A given 10 min before the challenge significantly inhibited the antigen-induced increase in ventilation overflow; the greatest inhibition seen 5-6 hr prior to the challenge. Pretreatment with 10 mg/kg FPL-55712 attenuated the increase in ventilation overflow during anaphylaxic shock. It is conceivable that inhibition of the leukotriene-mediated response is involved in the glucocorticoid-induced suppression of airway obstruction in anaphylaxis, and that inhibitory action of the glucocorticoid directly acting on the airway may account for the very fast onset of action.

Topics: Anaphylaxis; Animals; Antigens; Asthma; Bronchial Diseases; Chromones; Constriction, Pathologic; Dose-Response Relationship, Drug; Guinea Pigs; Male; Methylprednisolone; Ovalbumin; SRS-A; Time Factors

The effect of nedocromil sodium on PAF-acether- and antigen-induced bronchoconstriction (BC) and mediator release in lungs from actively sensitized guinea pigs and on the eosinophil content of bronchoalveolar lavage (BAL) was investigated. Guinea pigs were actively sensitized by two subcutaneous injections of 10 micrograms ovalbumin in 1 mg AI(OH)3 at 2-wk intervals. One week after the second (booster) injection, the lungs were removed, perfused in the absence or presence of indomethacin, and challenged at 10-min intervals with PAF-acether (1 and 100 ng) and with ovalbumin (1 micrograms). No inhibition of PAF-acether- and antigen-induced BC or mediator release from sensitized lungs was observed when nedocromil sodium (10 microM) was added directly to the buffer solution. By contrast, when guinea pigs were treated for 1 wk before the experiment with nedocromil sodium (30 mg/kg per day), BC and the release of leukotrienelike material (but not of thromboxane B2) to 1 ng PAF-acether were reduced by around 50% (p less than 0.05) and 62% (p less than 0.05), respectively. No inhibition was observed for 100 ng PAF-acether and 1 micrograms ovalbumin. Furthermore, nedocromil sodium markedly impaired histamine secretion induced by both PAF-acether and antigen administration. Nedocromil sodium did not affect the titers of circulating ovalbumin-specific immunoglobulin G, as detected by an enzyme-linked immunosorbent assay. The 1-wk treatment with nedocromil sodium also reduced markedly the proportion of eosinophils in the BAL of sensitized guinea pigs, whereas it was ineffective when injected once subcutaneously at the dose of 30 mg/kg 2 h before the experiment.(ABSTRACT TRUNCATED AT 250 WORDS)

Topics: Animals; Anti-Inflammatory Agents, Non-Steroidal; Bronchi; Bronchoalveolar Lavage Fluid; Constriction, Pathologic; Eosinophils; Female; Guinea Pigs; In Vitro Techniques; Indomethacin; Leukotriene Antagonists; Leukotrienes; Male; Nedocromil; Ovalbumin; Platelet Activating Factor; Quinolones; Respiratory Hypersensitivity; Thromboxane B2

Products of arachidonic acid have been implicated as potential mediators of allergic airway responses in sheep and in humans. We therefore measured the release of arachidonate metabolites into sheep bronchoalveolar lavage fluid (BALF) after local instillation of Ascaris antigen, using a highly specific and sensitive approach, gas chromatography-negative ion-chemical ionization mass spectrometry. Allergen instillation caused increases in the levels of the potent bronchoconstrictors prostaglandin (PG) D2 and thromboxane (TX) A2 (as reflected by levels of TXB2) and of their enzymatic metabolites, 9 alpha, 11 beta-PGF2 and 11-dehydro-TXB2, respectively. Potential bronchodilators, PGI2 and PGE2, were also formed in increased amounts. Levels of the 5-lipoxygenase products, leukotriene (LT) B4 and C4, were not significantly increased. Pretreatment of sheep with cyclooxygenase inhibitors was associated with a decrease in the release of cyclooxygenase products and a concomitant increase in the allergen-stimulated release of LTB4 and LTC4. Eicosanoids are formed promptly in vivo in sheep after allergen instillation: inhibition of cyclooxygenase results in augmented generation of leukotrienes in the airways of sensitive sheep in response to antigen challenge.

Topics: Allergens; Animals; Arachidonic Acid; Arachidonic Acids; Ascaris; Bronchi; Bronchoalveolar Lavage Fluid; Constriction, Pathologic; Cyclooxygenase Inhibitors; Histamine; Indomethacin; Leukotrienes; Lung; Meclofenamic Acid; Ovalbumin; Pollen; Prostaglandins; Sheep; Thromboxanes

Intravenous application of substance P (SP) (10 micrograms/kg) caused bronchoconstriction returning to baseline within 10 min. Pretreatment with SP did not influence the bronchoconstrictor response induced by allergen or carbachol.

Topics: Allergens; Animals; Bronchi; Bronchial Diseases; Carbachol; Constriction, Pathologic; Female; Guinea Pigs; Male; Ovalbumin; Substance P

The effect of antigen (ovalbumin) challenge on pulmonary hemodynamics, bronchoconstriction, and fluid filtration was investigated in Ringer's-perfused (non-recirculating) lungs that had been passively sensitized in vitro. Bolus ovalbumin injection (30 micrograms) produced immediate increases in pulmonary arterial pressure, peak intratracheal pressure, and lung weight within 1 min and secondary marked increases in intratracheal pressure and lung weight from 120 to 200 min. Electron microscopy of antigen-challenged isolated lungs showed evidence of both septal and intraalveolar edema. Ionophore A23187 (100 micrograms) challenge of nonsensitized lungs produced immediate pulmonary responses similar to antigen, whereas secondary increases in lung weight were smaller. Arachidonic acid pretreatment (1 microM) potentiated immediate antigen-induced increases in intratracheal pressure but did not affect pulmonary responses to ionophore challenge. Putative mediators of anaphylaxis including histamine, leukotrienes B4, C4, D4, and E4, platelet-activating factor, and substance P produced immediate changes in pulmonary arterial and/or intratracheal pressure similar to antigen challenge. Only platelet-activating factor and substance P partially mimicked the secondary edema formation noted following antigen challenge. Thus, antigen challenge in in vitro sensitized guinea pig lungs produced both immediate and secondary responses characterized by increases in vascular pressure, airway pressure, and edema formation. This occurred in the absence of circulating blood-formed elements and without a massive influx of cells. Synergism between mediators such as histamine, the leukotrienes, platelet-activating factor, and substance P released following antigen challenge may be necessary to produce the complete pathophysiological sequelae associated with antigen challenge in the perfused guinea pig lung.

Topics: Anaphylaxis; Animals; Antigens; Bronchi; Calcimycin; Constriction, Pathologic; Guinea Pigs; Hemodynamics; Immunization; In Vitro Techniques; Lung; Microscopy, Electron; Ovalbumin; Pulmonary Artery; Pulmonary Edema; Spasm

In guinea pigs sensitized with 1 microgram ovalbumin together with 100 mg Al(OH)3, somatostatin levels were selectively increased up to two and 3 times in tissue extracts from trachea and bronchi, respectively, but not in lung as compared to controls. The increase of somatostatin levels observed in trachea and bronchi after sensitization was associated with a decrease in the binding capacity of both high- and low-affinity binding sites (without changes in the affinity values) in the corresponding cytosolic fractions. These results suggests that an increase in airways somatostatin content may be involved in the pathogenesis of anaphylactic bronchoconstriction.

Topics: Anaphylaxis; Animals; Bronchi; Constriction, Pathologic; Cytosol; Guinea Pigs; Immunization; Lung; Male; Ovalbumin; Receptors, Neurotransmitter; Receptors, Somatostatin; Somatostatin; Trachea

Topics: Administration, Intranasal; Aerosols; Animals; Antibodies; Antigens; Bronchi; Bronchography; Cattle; Constriction, Pathologic; Disease Models, Animal; Dose-Response Relationship, Immunologic; Guinea Pigs; Hypersensitivity; Lung; Lung Compliance; Lung Volume Measurements; Ovalbumin; Pyrilamine; Respiration; Serum Albumin, Bovine; Tracheotomy