Dual Responders Research Articles

A PAF receptor antagonist inhibits acute airway inflammation and late‐phase responses but not chronic airway inflammation and hyperresponsiveness in a primate model of asthma

We have examined the effects of a PAF receptor antagonist, WEB 2170, on several indices of acute and chronic airway inflammation and associated changes in lung function in a primate model of allergic asthma. A single oral administration WEB 2170 provided dose related inhibition of the release of leukotriene C4 (LTC4) and prostaglandin D2 (PGD2) recovered and quantified in bronchoalveolar lavage (BAL) fluid obtained during the acute phase response to inhaled antigen. In addition, oral WEB 2170 treatment in dual responder primates blocked the acute influx of neutrophils into the airways as well as the associated late-phase airway obstruction occurring 6 h after antigen inhalation. In contrast, a multiple dosing regime with WEB 2170 (once a day for 7 consecutive days) failed to reduce the chronic airway inflammation (eosinophilic) and associated airway hyperresponsiveness to inhaled methacholine that is characteristic of dual responder monkeys. Thus, we conclude that the generation of PAF following antigen inhalation contributes to the development of lipid mediators, acute airway inflammation and associated late-phase airway obstruction in dual responder primates; however, PAF does not play a significant role in the maintenance of chronic airway inflammation and associated airway hyperresponsiveness in this primate model.

アレルギー性鼻炎患者におけるケミカル・メディエーターに関する研究 第二報 二相性反応の鼻汁中ヒスタミン，ロイコトリエン，キニンに関する検討

In order to clarify the details of a late phase response (LPR) in allergic rhinitis, serial changes of nasal symptoms and concentration of chemical mediators (histamine, leukotriene (LT) C4 and kinins) in nasal lavage fluid were investigated after the nasal antigen challenge in ten patients with perennial allergic rhinitis with a positive intradermal skin reaction to mite extract. Samples were collected periodically for 8 hours following the challenge. Nasal airway resistance (NAR) and clinical symptoms were also recorded serially. Three out of ten patients showed only early phase response (EPR) and the other seven patients showed both early and late phase response after the challenge. The chief nasal symptom in LPR was nasal obstruction. In EPR, concentrations of chemical mediators in the nasal lavage fluid always increased. In dual (early and late) phase responders, increases of chemical mediators in nasal lavage fluids were notable during both early and late phase responses. In EPR, there was a significant correlation between severity of sneezing attack and concentration of histamine. In LPR, increase of LTC4 level was significantly correlated with the increase of NAR. RAST score and daily nasal symptoms tended to be higher and more sever in dual phase responders compared with early phase responders. We suggest that the amounts of released chemical mediators during allergic reaction denoted the LPR in allergic rhinitis patients.

Late-phase bronchial vascular responses in allergic sheep

Sheep were classified on the basis of their airway response to Ascaris suum antigen aerosols as allergic or nonsensitive. Allergic sheep were classed as acute or dual responders. Acute responders had only an immediate increase in mean airflow resistance after antigen, whereas dual responders had an immediate and late-phase (6-8 h after antigen challenge) increase in mean airflow resistance; nonsensitive sheep had minimal airway responses to antigen (less than 30% increase from base line). The sheep were anesthetized 2 wk later and, after a left thoracotomy, were challenged with antigen to determine bronchial vascular responses; bronchial artery blood flow was measured with an electromagnetic flow probe. Airway responses to antigen aerosol challenge were similar in the anesthetized and conscious animals. The mean fall in bronchial vascular resistance (BVR) immediately after antigen challenge was similar in acute and dual responders (41 +/- 7 and 47 +/- 9% of base line, respectively). In dual responders, late-phase airway responses were preceded by a significant increase from base line in Qbr and a fall in bronchovascular resistance (BVR). The mean fall in BVR 6-8 h after antigen challenge in documented dual responders was significantly different from bronchial vascular responses in acute responders (59 +/- 3 vs. 89 +/- 10%, respectively). Sheep without airway responses to A. suum had no significant changes in bronchial hemodynamics or airways mechanics. Late-phase-associated changes in BVR are a specific response to antigen challenge and may be a sensitive index of mediators being released.(ABSTRACT TRUNCATED AT 250 WORDS)

Urinary leukotriene E 4 levels during early and late asthmatic responses

The sulphidopeptide leukotrienes C4 and D4 (LTC4, LTD4) are potent bronchoconstrictor mediators, released from human lung fragments after challenge with specific allergens in vitro. The purpose of this study was to measure urinary LTE4 (metabolite of LTC4 and LTD4) in subjects undergoing inhalation challenges with allergens or occupational sensitizing agents in the laboratory. Eighteen subjects with previously documented isolated early asthmatic responses (EARs), isolated late asthmatic responses (LARs), or dual (both early and late) asthmatic responses were studied. Urinary LTE4 levels increased in subjects who developed either isolated EARs (mean fall in FEV1, 27.98%) or early responses preceding LARs (mean fall in FEV1, 15.01%). The baseline levels of LTE4 were 150.26 (SEM, 49.5) pg/mg of creatinine in the isolated responders and 66.60 (SEM, 13.5) pg/mg of creatinine in the dual responders. These levels increased to 1816 (SEM, 606.1) pg/mg of creatinine (p = 0.041) and 174.80 (SEM, 40.1) pg/mg of creatinine (p = 0.025), respectively, after the EAR. The degree of maximal bronchoconstriction during the EAR correlated with the levels of LTE4 (r = 0.68; p = 0.001). No significant increase in urinary LTE4 levels occurred during the LAR. These results suggest that the LTE4 precursors, LTC4 and LTD4, are important bronchoconstrictor mediators causing EARs after allergen inhalation.

Tracheal smooth muscle strips from acute and dual responder allergic sheep requires different doses of ascaris antigen to alter its responsiveness

Tracheal smooth muscle strips from acute and dual responder allergic sheep requires different doses of ascaris antigen to alter its responsiveness

Effect of 15-(s)-Hydroxyeicosatetraenoic Acid on Allergen-induced Asthmatic Responses

15-(s)-hydroxyeicosatetraenoic acid (15-HETE), a major oxidative metabolite of arachidonic acid in human lungs, has complex actions on the 5-lipoxygenase pathway in different cell systems. We have examined the effect of inhaled 15-HETE on the early and late asthmatic responses (EAR and LAR) and the associated change in nonspecific bronchial responsiveness to inhaled allergen in 10 subjects with atopic asthma. On 2 separate days 3 wk apart, subjects inhaled either 70 nmol 15-HETE or the diluent (sodium phosphate buffer) in a randomized and double-blind fashion, followed by a dose of allergen that had previously been shown to produce a 25% fall in baseline FEV1. Analysis of the area under the FEV1 response time course curves (AUC) in the first hour revealed that preinhalation with 15-HETE increased the EAR by 39% from that achieved after the diluent (p less than 0.05). In the seven subjects who were classified as dual responders by developing a LAR previously (greater than 15% fall in baseline FEV1 3 to 8 h after allergen challenge), 15-HETE did not cause any significant change in the magnitude of the LAR when compared with that observed after placebo. The values of the provocation concentration of histamine causing a 20% fall in FEV1 (Pc20) at 8 h postchallenge were significantly reduced on both study days when compared with the corresponding preallergen challenge values, whether analyzed for the whole group or for the seven dual responders (p less than 0.05). 15-HETE had no effect on this allergen-acquired airway hyperresponsiveness to histamine when compared with the diluent.(ABSTRACT TRUNCATED AT 250 WORDS)

The Effect of an Increase in Inhaled Allergen Dose after Rimiterol Hydrobromide on the Occurrence and Magnitude of the Late Asthmatic Response and the Associated Change in Nonspecific Bronchial Responsiveness

We have used a short-acting beta 2-adrenoceptor agonist, rimiterol hydrobromide, to allow a larger dose of allergen to be administered to previous single "early allergen responders" to investigate if an increased dose of allergen could induce a late asthmatic response (LAR) and whether this would influence the subsequent level of allergen-acquired nonspecific bronchial hyperresponsiveness. Pretreatment with inhaled rimiterol hydrobromide 400 microgram enabled an increase in allergen dose inhaled by a geometric mean of 8.9-fold (range, 2 to 29.1) in eight atopic subjects with mild asthma who initially were classified as single early responders with a maximal fall in FEV 3 to 8 h after allergen challenge (Lmax) of less than 15% from baseline value. The magnitude of the early asthmatic response was similar to that obtained on the control day when allergen challenge was performed in the absence of rimiterol hydrobromide. Five subjects were converted to dual allergen responders with Lmax of greater than 15% from premedication baseline value. For the whole group, there was a significant increase in the magnitude of LAR whether calculated as Lmax (p less than 0.05) or as area under the FEV1 time response curve between 3 and 8 h postchallenge (p less than 0.01). The provocation concentrations of methacholine causing a 20% fall in FEV1 (PC20) at 8 h postchallenge were significantly reduced on both days when compared with the corresponding prechallenge values (p less than 0.05 on control day, p less than 0.01 on rimiterol day). However, despite the increase in the magnitude of LAR on the rimiterol day, the reduction in postchallenge PC20 did not differ significantly from that occurring on the control day.(ABSTRACT TRUNCATED AT 250 WORDS)

The effect of an increase in inhaled allergen dose after terfenadine on the occurrence and magnitude of the late asthmatic response

We have attempted to use a potent and selective histamine H1-receptor antagonist terfenadine to allow a larger dose of allergen to be administered to previous single early responders to investigate if an increased dose of allergen could induce a late asthmatic response. Pre-treatment with 180 mg of terfenadine enabled a geometric mean increase in allergen dose of 4.12-fold to be inhaled by eight atopic subjects with mild asthma, who initially were classified as single early responders, with maximal fall in FEV1 3-8 hr after allergen challenge (Lmax) of less than 15% from baseline value. The magnitude of early asthmatic response was similar to that obtained on the control day when allergen challenge was performed in the absence of terfenadine. Two subjects were converted to dual responders with Lmax of 23.1 and 24.3%, which occurred with a 32- and 65-fold increase in allergen dose respectively, and a 6- and 4.9-fold decrease in non-specific airways responsiveness measured as the cumulative provocative concentration of methacholine that caused a 20% fall in FEV1 from baseline. The remaining six subjects failed to achieve an Lmax of greater than 10% even with a 1.29-2.66-fold increase in allergen dose. For the group as a whole an increase in allergen dose was associated with an increase in overall bronchoconstrictor response 3-8 hr after challenge. These results indicate that it is possible to induce a late asthmatic response in a subject who previously demonstrated only an early response by increasing the dose of allergen inhaled.

The significance of specific IgE and IgG to dermatophagoides farinae according to the types of asthmatic reaction in house dust asthmatics

To investigate the role of specific IgE and IgG in the various types of asthmatic reaction, we measured specific IgE and IgG levels to Dermatophagoides farinae (D.farinae) using the D. farinae-radioallergosorbent test (RAST) and Phadebas IgG-RAST in 39 house dust asthmatics (11 early responders, 21 dual responders and 7 isolated late responders) and 12 negative responders on house dust bronchoprovocation. There were significant differences in the D. farinae-specific IgE level and skin reactivity to D. farinae and house dust among the 4 groups (p less than 0.05) and the specific IgE level of dual asthmatic responders was the highest and was significantly higher than that of early responders (p less than 0.05). The specific IgG level showed no differences among the 4 groups. These results suggested that the types of asthmatic reaction in house dust asthmatics were closely related to specific IgE level to D. farinae and the specific IgG level seemed not to be related to an isolated late response.

Cellular markers of inflammation in the airways of allergic sheep with and without allergen-induced late responses.

Allergic sheep respond to inhaled Ascaris suum antigen either with an acute bronchoconstriction alone (acute responders, AR) or both an acute and late bronchoconstriction (dual responders, DR). In this study, we determined if: (1) inflammatory cell composition of bronchoalveolar lavage (BAL) obtained during the late response differs between DR and AR; (2) the difference in inflammatory cells is dependent on the prechallenge BAL cell composition; and (3) drugs that block late airway responses also modify this airway inflammation. Antigen challenge caused significant immediate mean increases in specific lung resistance (SRL) both in DR (n = 28) and in AR (n = 14), but only DR had a late increase in SRL. There were no differences between the two groups in total cell returns or in the percentage of neutrophils in BAL 7.5 to 8 h after challenge, but DR had a 3.5-fold increase (p less than 0.05) in the percentage of eosinophils. Methylprednisolone succinate (15 mg/kg intravenously) given to DR (n = 7) 3 h after antigen challenge blocked the late airway response and the eosinophil response. When BAL was performed both before and after (i.e., 7.5 to 8 h) antigen challenge, similar results were observed: AR (n = 7) and DR (n = 14) exhibited characteristic airway responses. No significant differences in prechallenge BAL cell composition were observed between AR and DR; after challenge both groups showed increases in neutrophils, but only the DR showed an increase (p less than 0.05) in eosinophils. Pretreatment of DR with the antiallergic agents (cromolyn sodium or nedocromil sodium aerosol, 20 mg) blocked the immediate and late responses and the late increase in BAL eosinophils.(ABSTRACT TRUNCATED AT 250 WORDS)

Indomethacin and FPL-57231 inhibit antigen-induced airway hyperresponsiveness in sheep.

We compared the development of antigen-induced airway hyperresponsiveness (AHR) 24 h after challenge with Ascaris suum antigen in allergic sheep with acute (n = 7) and with dual (n = 7) airway responses and then attempted to modify this AHR. Cholinergic airway responsiveness was determined by measuring the carbachol dose required to increase specific lung resistance (sRL) 150% (i.e., PC150). Subsequently the sheep were challenged with antigen and sRL was measured at predetermined times to document the presence or absence of a late response. PC150 was redetermined 24 h later followed by bronchoalveolar lavage (BAL) to assess inflammation. Only dual responders developed AHR (PC150 decreased, P less than 0.05). There were no significant differences in BAL between the two groups. Six dual responders were then, on separate occasions (greater than or equal to 3 wk), pretreated with placebo, indomethacin (2 mg/kg iv), or a leukotriene antagonist, FPL-57231 (30 mg inhaled). Neither agent significantly affected the acute response to antigen. Only FPL pretreatment blocked the late response, but both agents blocked the antigen-induced AHR 24 h later. BAL at 24 h showed no significant differences. These results indicate that only dual responders develop AHR 24 h after antigen challenge. This AHR appears independent of the late increase in sRL or the severity of pulmonary inflammation. AHR appears to be sensitive to agents that interfere with the early release or actions of cyclooxygenase and lipoxygenase metabolites in dual responders.

Differences in airway responsiveness to leukotriene D 4 in allergic sheep with and without late bronchial responses

Allergic sheep respond to inhaled Ascaris suum antigen with either acute and late bronchial obstructions (dual responders) or only acute bronchoconstriction (acute responders). In this study we tested the hypothesis that one factor which may distinguish between these two populations is the difference in sensitivity to a specific mediator of airway anaphylaxis, leukotriene (LT) D 4 (a major component of slow reacting substance of anaphylaxis). We postulated that if the hypothesis was correct than dual responders should demonstrate increased airway responses to inhaled LTD 4 and that this increased responsiveness should also be reflected by a more severe response to inhaled antigen. To test this we used animals from both groups with the same degree of non-specific airway responsiveness to carbachol and determined their airway responses to controlled inhlation challenges with synthetic LTD 4 and barAscaris suum antigen. Airway responsiveness to carbachol was determined by measuring the change in specific lung resistance (SR L) to increasing concentrations of carbachol aerosol, and then identifying, by linear interpolation, the provocative carbachol concentration which produced a 150% increase (PC 150) in SR L. Airway responses to LTD 4, and antigen were determined by measuring the percentage change in SR L after a controlled inhlation challenge with either aerosol. Airway responsiveness to carbachol was not different between the two groups. There was, however, a difference (p<0.05) in the airway response to the same dose of LTD 4 in the two groups. Dual responders showed a 297±72% increase in SR L as compared to a 90±13% increase in SR L in the acute responders. Dual responders also showed a greater immediate and more prolonged response to antigen than did acute responders. These results suggest that increased responsiveness to LTD 4 may be one factor which may distinguish dual responders from acute responders.