Bronchial aspirin challenge causes specific eicosanoid response in aspirin-sensitive asthmatics

[Aspirin: allergy or intolerance]

PURPOSE

The paper describes the clinical characteristics of patients with aspirin-induced asthma and/or urticaria, angioedema, shock, the results of the challenge tests and the evolution of this disease.

MAIN POINT

The authors present the different arguments supporting the physiopathological mechanisms from genetics to the inhibition of cyclooxugenase or the leukotriene hypothesis.

PROSPECTIVES

Finally, they recall the methodology to be used for a good clinical practice on this controversial field of research.

Differential metabolism of arachidonic acid in nasal polyp epithelial cells cultured from aspirin-sensitive and aspirin-tolerant patients

The mechanism of aspirin (acetylsalicylic acid [ASA]) sensitivity associated with severe asthma and chronic rhinosinusitis with nasal polyps ("aspirin triad") has been attributed to arachidonic metabolism alternations, although the putative biochemical defects have not been elucidated. The aim of this study was assessment of the hypothesis that local production of eicosanoids in the respiratory epithelium in patients with ASA-sensitive asthma/rhinosinusitis (ASARS) differs from that of ASA-tolerant patients with rhinosinusitis (ATRS). Nasal polyps were obtained from 10 patients with ASARS and 15 with ATRS during routine polypectomies, and epithelial cells (ECs) were cultured on bovine collagen type I matrix (Vitrogen 100), in medium supplemented with growth factors. The generation of eicosanoids in supernatants of confluent ECs (6 to 8 d of culture; purity > 98%) was quantified by immunoassays. Unstimulated ECs from ASARS patients generated significantly less prostaglandin E(2)(PGE(2)) compared with ATRS (0.8 +/- 0.3 versus 2. 4 +/- 0.5 ng/microg double-stranded deoxyribonucleic acid [dsDNA], respectively), although a similar relative increase in response to calcium ionophore and inhibition with ASA was observed in both groups. Basal levels of 15-hydroxyeicosatetraenoic acid (15-HETE) were not different between groups, and calcium ionophore enhanced its production to a similar extent. However, cells incubation with 200 microM ASA for 60 min resulted in a significant increase (mean +359%) in 15-HETE generation only in ASARS patients, whereas no effect of ASA on 15-HETE generation in ATRS patients was observed. PGF(2alpha) generation was similar in both groups, and no significant generation of PGD(2) or leukotriene C(4) (LTC(4)) was observed in epithelial cell cultures from either group. Our results indicate that nasal polyps ECs from ASA-sensitive patients have significant abnormality in basal and ASA-induced generation of eicosanoids which may be causally related to the mechanism of ASA sensitivity.

Efficacy of leukotriene receptor antagonist in bronchial hyperresponsiveness and hypersensitivity to analgesic in aspirin-intolerant asthma

BACKGROUND

Albeit its exact pathogenesis is still ambiguous; aspirin-intolerant asthma is one of several types of asthma for which antileukotriene therapy is useful, because it is widely accepted that bronchial over-production of leukotrienes may be involved in its pathogenesis. Pranlukast (8-[p-(4-phenylbutyloxy) benzol] amino-2-(tetrazol-5-yl)-4-oxo-4H-1-benzopyran hemihydrate), a selective cysteinyl leukotriene receptor antagonist, is now widely used in the treatment of asthma.

OBJECTIVE

This study was designed to investigate the protective effect of pranlukast on airway sensitivity to sulpyrine provocation testing, bronchial responsiveness to methacholine provocation testing, and to investigate whether this protective activity is associated with a reduction in aspirin-induced excretion of urinary LTE4 (uLTE4), a marker of the cysteinyl leukotriene (LT) overproduction that participates in the pathogenesis of aspirin-induced asthma.

METHODS

We assessed the effects of pretreatment with pranlukast on bronchoconstriction precipitated by inhalation of methacholine and sulpyrine in 16 adult patients with mild or moderate aspirin-intolerant asthma; those who were in stable clinical condition and were hypersensitive to sulpyrine provocation testing were allocated to this study. A double-blind, randomized, crossover design was used. uLTE4 was measured using combined reverse-phase high-performance liquid chromatography (rp-HPLC)/enzyme immunoassay.

RESULTS

Pranlukast protected against analgesic-induced bronchoconstriction through mechanisms that were not related to the bronchodilator property, but were related to the improvement both of bronchial hyperresponsiveness and hypersensitivity to analgesic (P < 0.005 and P < 0.0001). Pranlukast showed little effect on excretion of uLTE4.

CONCLUSION

These results support the hypothesis that cysteinyl leukotriene is one of the most important components in the pathogenesis of aspirin-intolerant asthma. Pranlukast improves not only hypersensitivity to analgesic, but also bronchial hyperresponsiveness in aspirin-intolerant asthma. It is also possible that pranlukast has another anti-asthmatic effect besides that of a leukotriene receptor antagonist.

Leukotrienes, leukotriene receptor antagonists and leukotriene synthesis inhibitors in asthma: an update. Part I: synthesis, receptors and role of leukotrienes in asthma

Asthma is a chronic inflammatory disease associated with airflow obstruction. Airflow obstruction results from contraction of airway smooth muscle, mucosal oedema, increased secretion of mucus and infiltration of the airway wall by inflammatory cells, particularly eosinophils. Leukotrienes are thought to contribute to the pathophysiology of asthma. Leukotrienes are synthesised from arachidonic acid by a specific synthesis pathway whose key enzyme is 5-lipoxygenase. Cysteinyl leukotrienes (leukotrienes C4, D4 and E4) have been shown to mimic all the pathologic changes that are characteristic of asthma, whereas leukotriene B4 does not appear to exert biological properties relevant to asthma. Cysteinyl leukotrienes bind to two receptor subtypes: CysLT1 and CysLT2. Most of the biological properties of cysteinyl leukotrienes relevant to asthma are mediated through CysLT1 receptor stimulation.

Anti-inflammatory effect of roxithromycin in patients with aspirin-intolerant asthma

BACKGROUND

Fourteen-membered macrolides, such as roxithromycin, have been reported to exhibit other pharmacological activity including anti-asthmatic effects, besides antibiotic activity.

OBJECTIVE

This study was designed to investigate the protective effect of roxithromycin on airway responsiveness to the sulpyrine provocation test and to investigate whether this protective activity is associated with a reduction in aspirin-induced excretion of urinary leucotriene E4 (u-LTE4), a marker of cysteinyl leucotriene overproduction that participates in the pathogenesis of aspirin-intolerant asthma. Also, the present study was designed to examine whether or not its anti-asthmatic activity was associated with a reduction in eosinophilic inflammation.

METHODS

For 8 weeks before analysis, subjects received 150 mg of roxithromycin or matching placebo twice daily. We assessed the effects of pretreatment with roxithromycin on bronchoconstriction precipitated by inhalation of sulpyrine in 14 adult patients with mild or moderate aspirin-intolerant asthma; those who were in stable clinical condition and were hyperresponsive to sulpyrine provocation test were allocated to this study. A double-blind, randomized, crossover design was used. Urinary LTE4 was measured by a combined reverse-phase high-performance liquid chromatography (rp-HPLC) enzyme immunoassay on sulpyrine provocation testing day. Blood and sputum samples were taken in the morning on the sulpyrine provocation testing day. Eosinophil counting and measurement of eosinophilic cationic protein (ECP) were performed.

RESULTS

After the 8 weeks of treatment with roxithromycin, patients' symptoms, blood eosinophils, serum ECP, sputum eosinophils, and sputum ECP were significantly decreased. On the other hand, values of PC20-sulpyrine did not improve after roxithromycin at all. Furthermore, although challenge with sulpyrine caused a significant increase in u-LTE4, pretreatment with roxithromycin or placebo did not affect excretion of u-LTE4.

CONCLUSION

Although roxithromycin does not have antileucotriene effects, it has an antibronchial inflammatory effect associated with eosinophilic infiltration. This study raises further interesting therapeutic possibilities and warrants further trials of new approaches to the treatment of aspirin-intolerant asthma.

Leukotrienes, leukotriene receptor antagonists and leukotriene synthesis inhibitors in asthma: an update. Part II: clinical studies with leukotriene receptor antagonists and leukotriene synthesis inhibitors in asthma

The demonstration that leukotrienes, mainly cysteinyl leukotrienes, have biological properties relevant to the pathogenesis of asthma has stimulated the development of many therapeutic compounds to block these deleterious effects. Two main classes of leukotriene modulators have been developed: CysLT1 receptor antagonists and leukotriene synthesis inhibitors. This article reviews the pharmacodynamics, the effects on baseline airway function, the protective effects in airway challenges as well as the results in chronic asthma of the different leukotriene modulators. In addition, the complementary anti-inflammatory effect of leukotriene modulators to that of corticosteroids and H1-histamine receptor antagonists is reviewed. Finally, a concise overview of the clinical responsiveness to this new class of drug, the safety and the drug interactions as well as the place in the strategies of treatment for asthmatic patients of the leukotriene modulators is also provided.

Different effects of inhaled aspirinlike drugs on allergen-induced early and late asthmatic responses

Little is known about the anti-asthmatic effects of powerful anti-inflammatory agents such as aspirin-like drugs. We compared the effects of two aspirin-like drugs with different pharmacologic activities, sodium salicylate (SSA) and indomethacin, with the effect of lysine acetylsalicylate (LASA), inhaled 30 min before challenge, on the early and the late asthmatic response induced by a single dose of allergen causing a 25% decrease in FEV1 in a preliminary challenge. Inhaled SSA partially prevented both the early and late response, providing a protection with respect to placebo of 22 +/- 6% in the early phase and 23 +/- 9% in the late phase of the response. These values were lower (but not significantly) than those of LASA (41 +/- 9% and 39 +/- 11%, respectively). In a second group of patients, indomethacin failed to affect the early response, while LASA provided a protection of 31 +/- 7%. However, these two drugs were equally effective in reducing the late response (44 +/- 18% and 39 +/- 17% protection for LASA and indomethacin, respectively). In subjects with an early response, despite being ineffective in preventing allergen-induced bronchoconstriction, indomethacin blocked the allergen-induced increase in bronchial hyperresponsiveness measured 2 h after challenge. We conclude that inhaled salicylates, but not indomethacin, exert a protective activity against the early allergic response. This difference is not explained by the different pattern of cyclooxygenase inhibitory activity of these drugs.

Salmeterol prevents aspirin-induced attacks of asthma and interferes with eicosanoid metabolism

We determined the effect of a long acting beta2-agonist, salmeterol, on aspirin-induced asthma (AIA) attacks and urinary release of eicosanoids in a double-blind, placebo-controlled, crossover study in 10 asthmatics sensitive to aspirin. The patients inhaled 50 microgram of salmeterol or placebo 15 min prior to a cumulative challenge with increasing doses of lysine-aspirin (L-ASA) (Part I), and before a single, predetermined dose of L-ASA that caused a 20% fall in FEV1 (PD20) (Part II). Salmeterol significantly attenuated aspirin-precipitated bronchoconstriction and the increase in urinary LTE4. Salmeterol also prevented the decrease in blood eosinophils, and abolished the correlation between the urinary levels of LTE4 and provocative doses of aspirin. In addition, PGD-M, the major urinary metabolite of PGD2, increased after L-ASA inhalation in six of nine subjects; this increase was blocked in all six by salmeterol. The protective effect of salmeterol on aspirin-induced attacks and mediator release suggests that it may be efficacious in aspirin-sensitive asthma.

Benefits from adding the 5-lipoxygenase inhibitor zileuton to conventional therapy in aspirin-intolerant asthmatics

From bronchoprovocation studies and investigations of the acute effects of drugs that inhibit leukotrienes (LT), the hypothesis has emerged that leukotrienes are important mediators of airway obstruction and other symptoms in aspirin-intolerant asthma (AIA). However, it has yet not been shown if subjects with AIA respond favorably to clinical treatment with leukotriene inhibitors. Therefore, in a double-blind placebo-controlled crossover study, we examined the effects of 6 wk of treatment with the leukotriene-pathway inhibitor zileuton (600 mg, four times daily) in 40 patients with well-characterized AIA. The treatment was added to existing therapy, which included medium to high doses of inhaled (average daily dose 1,030 microg of beclomethasone or budesonide) or oral glucocorticosteroids (4 to 25 mg/d) for all but one of the patients. On top of this treated baseline, there were no significant effects of adding placebo, indicating that their asthma was kept relatively stable. However, there was an acute and chronic improvement in pulmonary function after treatment with zileuton, expressed both as increased FEV1 from baseline compared with placebo, and higher morning and evening peak expiratory flow rate (PEFR) values on zileuton treatment compared with placebo. The improvements occurred despite lower use of rescue bronchodilator with zileuton. Zileuton also diminished nasal dysfunction, which is one of the cardinal signs of AIA. There was a remarkable return of smell, less rhinorrhea, and a trend for less stuffiness and higher nasal inspiratory flow during treatment with zileuton. Zileuton caused a small but distinct reduction of bronchial hyperresponsiveness to histamine and inhibited aspirin-induced bronchoconstriction. Zileuton inhibited urinary excretion of LTE4 but did not change airway reactivity to inhaled LTD4, supporting that zileuton specifically inhibited leukotriene biosynthesis. The findings indicate that leukotrienes are important mediators of persistent airway obstruction and chronic nasal dysfunction in AIA. The study also suggests that addition of a leukotriene pathway inhibitor such as zileuton may bring about greater control of asthma than what is achieved by treatment with medium to high doses of glucocorticosteroids alone.

Overexpression of leukotriene C4 synthase in bronchial biopsies from patients with aspirin-intolerant asthma

Aspirin causes bronchoconstriction in aspirin-intolerant asthma (AIA) patients by triggering cysteinyl-leukotriene (cys-LT) production, probably by removing PGE2-dependent inhibition. To investigate why aspirin does not cause bronchoconstriction in all individuals, we immunostained enzymes of the leukotriene and prostanoid pathways in bronchial biopsies from AIA patients, aspirin-tolerant asthma (ATA) patients, and normal (N) subjects. Counts of cells expressing the terminal enzyme for cys-LT synthesis, LTC4 synthase, were fivefold higher in AIA biopsies (11.5+/-2.2 cells/mm2, n = 10) than in ATA biopsies (2.2+/-0.7, n = 10; P = 0. 0006) and 18-fold higher than in N biopsies (0.6+/-0.4, n = 9; P = 0. 0002). Immunostaining for 5-lipoxygenase, its activating protein (FLAP), LTA4 hydrolase, cyclooxygenase (COX)-1, and COX-2 did not differ. Enhanced baseline cys-LT levels in bronchoalveolar lavage (BAL) fluid of AIA patients correlated uniquely with bronchial counts of LTC4 synthase+ cells (rho = 0.83, P = 0.01). Lysine-aspirin challenge released additional cys-LTs into BAL fluid in AIA patients (200+/-120 pg/ml, n = 8) but not in ATA patients (0. 7+/-5.1, n = 5; P = 0.007). Bronchial responsiveness to lysine-aspirin correlated exclusively with LTC4 synthase+ cell counts (rho = -0.63, P = 0.049, n = 10). Aspirin may remove PGE2-dependent suppression in all subjects, but only in AIA patients does increased bronchial expression of LTC4 synthase allow marked overproduction of cys-LTs leading to bronchoconstriction.

Activated eosinophils elicit substance P release from cultured dorsal root ganglion neurons

This study was performed to test the hypothesis that activated eosinophils or their secretory products can directly stimulate sensory neurons to release their neuropeptides. Neurons derived from neonatal rat dorsal root ganglia (DRG), which synthesize and store sensory neuropeptides, were placed in primary cell culture and were exposed to eosinophils or their bioactive mediators. The resultant release of substance P (SP) was measured by enzyme-linked immunosorbent assay and was expressed as a percent (mean +/- SE) of total neuronal SP content. Eosinophils were isolated from human volunteers with a history of allergic rhinitis and/or mild asthma and were activated by incubation with cytochalasin B (5 micrograms/ml) and N-formyl-methionyl-leucyl-phenylalanine (FMLP, 1 microM). Activated eosinophils [6 x 10(6)/ml, suspended in Hanks' buffered salt solution (HBSS)] applied to cultured DRG neurons for 30 min increased basal SP release 2.4-fold compared with HBSS-exposed neurons (activated eosinophils 11.10 +/- 2.48% vs. HBSS 4.59 +/- 0.99%; P = 0.002), whereas neither nonactivated eosinophils nor cytochalasin B and FMLP in HBSS influenced SP release. Additional cultured DRG neurons were exposed to soluble products made by eosinophils. Compared with SP release under control conditions (2.37 +/- 0.34%), major basic protein (MBP) increased release in a concentration-related fashion (e.g., 3 microM MBP: 6.23 +/- 0.67%, P = 0.006 vs. control), whereas neither eosinophil cationic protein (3 microM), eosinophil-derived neurotoxin (3 microM), leukotriene D4 (500 nM), platelet-activating factor (100 nM), nor H2O2 (100 microM) affected SP release. These studies demonstrate that activated eosinophils can stimulate cultured DRG neurons directly and suggest that MBP may be the responsible mediator.

Intranasal fluticasone propionate for chronic eosinophilic rhinitis in patients with aspirin-induced asthma

We performed a double-blind, crossover, placebo-controlled study on the effect of fluticasone propionate (FP) treatment on chronic eosinophilic rhinosinusitis in 15 patients with aspirin-induced asthma (AIA). There were 10 women and five men aged 32-60 years; average: 45 years. After a 10-day run-in period, patients underwent two 4-week treatment courses (FP vs placebo), separated by a 2-week washout interval. Clinical activity of FP was evaluated by daily measurement of peak nasal inspiratory flow (PNIF) and a scoring system of subjective symptoms. Nasal challenges with E-lysine aspirin, using active anterior rhinomanometry, were performed at the entry and on the last day of each treatment period. Weekly mean values of symptom scores were generally lower and PNIF measurements higher during treatment with FP than with placebo. This difference was statistically significant for most recorded parameters for the whole 4-week FP treatment. On average, the reactions evoked by aspirin nasal challenge were significantly shorter and milder after treatment with FP than with placebo. In 8/13 patients, FP completely prevented aspirin-precipitated nasal reaction, whereas protection after placebo was observed in only 2/12 subjects (P = 0.004). We conclude that intranasal FP is an effective therapy for chronic eosinophilic rhinitis in patients with AIA.