Eicosanoids in bronchoalveolar lavage fluid of aspirin-intolerant patients with asthma after aspirin challenge

Early presentation with angioedema and urticaria in cross-reactive hypersensitivity to nonsteroidal antiinflammatory drugs among young, Asian, atopic children

OBJECTIVE

Nonsteroidal antiinflammatory drugs (NSAIDs), mainly ibuprofen, are used extensively among children as analgesic and antipyretic agents. Our initial survey in the Kendang Kerbau Children's Hospital in Singapore showed NSAIDs to be the second most common adverse drug reaction-causing medications among children of Asian descent. We attempted to characterize the clinical and epidemiologic profile of NSAID reactions in this group of patients.

METHODS

A retrospective case series from a hospital-based pediatric drug allergy clinic was studied. A diagnosis of NSAID hypersensitivity was made with a modified oral provocation test. Atopy was evaluated clinically and tested with a standard panel of skin-prick tests. We excluded from analysis patients with any unprovoked episodes of urticaria and/or angioedema, patients < 1 year of age, and patients who refused a diagnostic challenge test.

RESULTS

Between March 1, 2003, and February 28, 2004, 24 patients, including 14 male patients (58%) and 18 Chinese patients (75%), with a mean age of 7.4 years (range: 1.4-14.4 years), were diagnosed as having cross-reactive NSAID hypersensitivity. A family history consistent with NSAID hypersensitivity was elicited for 17% of patients. None of the patients reported any episodes of angioedema/urticaria unrelated to NSAIDs. The median cumulative reaction-eliciting dose was 7.1 mg/kg. Facial angioedema developed for all patients (100%) and generalized urticaria for 38% of challenged patients, irrespective of age. There was no circulatory compromise, but respiratory symptoms of tachypnea, wheezing, and/or cough were documented for 42% of patients. A cross-reactive hypersensitivity response to acetaminophen was documented for 46% of our patients through their history and for 25% through diagnostic challenge. Compared with patients with suspected adverse drug reactions to antibiotics, patients in the NSAID group were older (7.4 vs 4.8 years) and more likely to have a diagnosis of asthma (odds ratio: 7.5; 95% confidence interval: 3.1-19).

CONCLUSIONS

Early presentations of facial angioedema and urticaria are key features of dose- and potency-dependent, cross-reactive reactions to NSAIDs in a subpopulation of young, Asian, atopic children. Significant overlap with acetaminophen hypersensitivity, especially among very young patients, for whom the use of a cyclooxygenase-2-specific medication may not be feasible, severely limits options for medical antipyretic treatment.

Expression of the cysteinyl leukotriene receptors cysLT(1) and cysLT(2) in aspirin-sensitive and aspirin-tolerant chronic rhinosinusitis

BACKGROUND

Cysteinyl leukotrienes play a disease-regulating role in rhinosinusitis and asthma, particularly aspirin-sensitive disease. They act through 2 G-protein coupled receptors termed cysteinyl leukotriene type 1 receptor (cysLT 1 ) and cysteinyl leukotriene type 2 receptor (cysLT 2 ). We previously compared expression of cysLT 1 on mucosal leukocytes in patients with aspirin-sensitive and aspirin-tolerant rhinosinusitis.

OBJECTIVE

To compare expression of cysLT 1 and cysLT 2 on leukocytes, mucus glands, and epithelium in 32 patients with chronic polypoid rhinosinusitis (21 aspirin-sensitive, 11 aspirin-tolerant) and 9 normal controls.

METHODS

Total numbers of CD45 + leukocytes, percentages of these cells expressing cysLT 1 or cysLT 2 , and percentages of the total epithelial and glandular areas expressing cysLT 1 or cysLT 2 were measured in sections of nasal biopsies by using immunohistochemistry and image analysis.

RESULTS

The percentages of mucosal CD45 + leukocytes expressing cysLT 1 were significantly ( P < .0001) elevated in the aspirin-sensitive but not the aspirin-tolerant patients compared with the controls. In contrast, the percentages of leukocytes expressing cysLT 2 did not differ significantly in the 3 groups. On epithelial and glandular cells, expression of cysLT 2 significantly exceeded that of cysLT 1 in both the patients with rhinosinusitis and the controls ( P < or = .004), although there was no significant difference in the expression of either receptor in the patients with rhinosinusitis (aspirin-sensitive or aspirin-tolerant) and the controls.

CONCLUSION

Although cysLT 1 expression predominates on inflammatory leukocytes in patients with aspirin-sensitive rhinosinusitis, the effects of cysteinyl leukotrienes on glands and epithelium may be mediated predominantly through cysLT 2. This has potentially important therapeutic implications.

Medications as asthma triggers

Certain medications can generate asthma symptoms, with the potential to cause considerable morbidity. This article focuses on the common drugs that have the potential to cause distinct respiratory reactions in asthmatics: aspirin and other nonsteroidal anti-inflammatory drugs, beta-blockers, and angiotensin-converting enzyme inhibitors. The means by which these medications can trigger asthma vary in terms of acuity of onset, severity, and the mechanisms involved. The general and most practical approach is avoidance and cautious use of these drugs in asthmatics. However, these classes of medications can exert a major role in the management of common and serious diseases. Fortunately, controller therapy for asthma and alternative or more selective medications for the treatment of these conditions are now available.

Adverse respiratory reactions to aspirin and nonsteroidal anti-inflammatory drugs

Aspirin-exacerbated respiratory disease (AERD) is an adult-onset condition that manifests as asthma, rhinosinusitis/nasal polyps, and sensitivity to aspirin and other cyclooxygenase-1 (COX-1)-inhibitor nonsteroidal anti-inflammatory drugs (NSAIDs). There is no cross-sensitivity to highly selective COX-2 inhibitors. AERD is chronic and does not improve with avoidance of COX-1 inhibitors. The diagnosis of AERD is made through provocative challenge testing. Following a positive aspirin challenge, patients can be desensitized to aspirin and NSAIDs. The desensitized state can be maintained indefinitely with continued daily administration. After desensitization, there is an approximately 48-hour refractory period to adverse effects from aspirin. The pathogenesis of AERD remains unknown, but these patients have been shown to have multiple abnormalities in arachidonic acid metabolism and in cysteinyl leukotriene 1 receptors. AERD patients can take up to 650 mg of acetaminophen for analgesic or antipyretic relief. Patients can also use weak COX-1 inhibitors, such as sodium salicylate or choline magnesium trisalicylate. Treatment of AERD patients with antileukotriene medications has been helpful but not preferential when compared with non-AERD patients. An alternative treatment for many AERD patients is aspirin desensitization. This is particularly effective in reducing upper-airway mucosal congestion, nasal polyp formation, and systemic steroids.

The emerging role of leukotriene modifiers in allergic rhinitis

Leukotriene modifiers have been shown to be efficacious in the treatment of asthma. Because of this success, and the fact that leukotrienes can be recovered not only from bronchoalveolar lavage fluid but also nasal lavage fluid, some researchers have suggested that these medications may also be useful for treating allergic rhinitis. Because the upper and lower airways are linked physically, there has been an assumption that therapy for upper and lower airway disease should be similar. This critical appraisal examines available data both supporting and refuting the emerging role of leukotriene modifiers in the treatment of allergic rhinitis. Although many studies have shown an improvement in nasal symptoms when comparing a leukotriene modifier with placebo, few studies have conclusively shown that a leukotriene modifier is any more effective in treating allergic rhinitis than an antihistamine. Results from several reported studies suggest that the addition of a leukotriene antagonist to an antihistamine is no more efficacious than antihistamine alone. However, many of these studies were small and/or primarily designed to examine the asthmatic response, with nasal symptoms being a lesser endpoint. To better understand how, where, and when leukotriene modifiers should be used in the armamentarium of therapies for allergic rhinitis, larger clinical investigations designed specifically to study allergic rhinitis need to be undertaken. We conclude that currently, the data do not support widespread use of a leukotriene modifier with or without an antihistamine in place of an intranasal corticosteroid with or without an antihistamine in the treatment of allergic rhinitis.

Induced sputum inflammatory mediator concentrations in chronic cough

Previous studies have shown evidence of airway inflammation in patients with chronic cough and have suggested that the cough may be due to release of tussive mediators and activation of afferent sensory nerve endings. We measured the concentration of various proinflammatory and tussive mediators in induced sputum supernatants from 20 patients with cough variant asthma or eosinophilic bronchitis, 20 patients with nonasthmatic chronic cough, 22 patients with idiopathic chronic cough, and 18 healthy control subjects. We measured histamine, cysteinyl-leukotrienes, prostanoids (prostaglandin D2 and prostaglandin E2), and interleukin-8 by enzyme immunoassay. The median sputum histamine concentrations were significantly higher in patients with idiopathic chronic cough (8.0 ng/ml) and cough variant asthma/eosinophilic bronchitis (10.2 ng/ml) than in normal subjects (2.6 ng/ml; 95% confidence interval of difference from idiopathic chronic cough, 0.8 to 25.8 [p = 0.009] and 95% confidence interval of difference from cough variant asthma/eosinophilic bronchitis, 1.1 to 20.1 [p = 0.01]). Median sputum prostaglandin D2 and prostaglandin E2 concentrations were significantly higher in all categories of chronic cough. Our findings support the view that there is release of inflammatory and tussive mediators in patients with chronic cough and suggest that there might be similarities in the mechanism of cough in a diverse range of conditions.

Adverse reactions to aspirin and nonsteroidal antiinflammatory drugs (NSAIDs)

BACKGROUND

Aspirin can provoke reactions ranging from respiratory to cutaneous in those susceptible individuals. There has been particular attention looking at the role of cyclooxygenase enzymes and 2 and their role in aspirin exacerbated respiratory disease.

OBJECTIVE

Patients who present with a spectrum of allergic and pseudoallergic reactions to aspirin pose a special challenge for the physician. This article discusses proposed classification system, clinical manifestations, pathogenesis of disease, and current treatment options of aspirin related disease.

METHODS

Relevant articles in the medical literature were. derived from searching the MEDLINE database. Sources also include review articles, randomized control trials, and standard textbooks of allergy and immunology.

RESULTS

Aspirin-exacerbated respiratory disease remains a complex, heterogeneous disease with manvaried clinical presentations. There have been many advances in trying to elucidate the pathogenesis of this disease. The classification system presented will provide greater ease when reading the literature and communicating with one another. Oral aspirin challenge remains the diagnostic test of choice for both respiratory and cutaneous reactions. Aspirin desensitization is an option for those with refractory respiratory disease or who require aspirin for other medical conditions.

CONCLUSIONS

This review discusses the challenges in classification, diagnosis and treatment of those patients with a sensitivity to aspirin. Special attention is made to the possible mechanisms mediating disease progression and how specific. Therapies, such as the leukotriene modifiers may be helpful.

Sensitivity to nonsteroidal anti-inflammatory drugs

BACKGROUND

Aspirin can provoke reactions ranging from respiratory to cutaneous in susceptible individuals. There has been particular attention looking at the role of cyclo-oxygenase enzymes 1 and 2 and their role in aspirin-exacerbated respiratory disease.

OBJECTIVE

Patients who present with a spectrum of allergic and pseudoallergic reactions to aspirin pose a special challenge for the physician. This article discusses proposed classification system, clinical manifestations, pathogenesis of disease, and current treatment options of aspirin-related disease.

DATA SOURCES

Relevant articles in the medical literature were derived from searching the MEDLINE database with key terms aspirin-sensitive asthma, cyclo-oxygenase enzymes 1 and 2. Sources also include review articles, randomized control trials, and standard textbooks of allergy and immunology.

RESULTS

Aspirin-exacerbated respiratory disease remains a complex, heterogenous disease with varied clinical presentations. There have been many advances in trying to elucidate the pathogenesis of this disease. The classification system presented will provide greater ease when reading the literature and communicating with one another. Oral aspirin challenge remains the diagnostic test of choice for both respiratory and cutaneous reactions. Aspirin desensitization is an option for those with refractory respiratory disease or who require aspirin for other medical conditions.

CONCLUSIONS

This review discusses the challenges in classification, diagnosis, and treatment of those patients with a sensitivity to aspirin. Special attention is made to the possible mechanisms mediating disease progression and how specific therapies, such as leukotriene modifiers, may be helpful.

Leukotriene-receptor expression on nasal mucosal inflammatory cells in aspirin-sensitive rhinosinusitis

BACKGROUND

Patients with asthma who have aspirin sensitivity have greater cysteinyl leukotriene production and greater airway hyperresponsiveness to the effects of inhaled cysteinyl leukotrienes than their aspirin-tolerant counterparts. We hypothesized that the latter effect reflects elevated expression of the cysteinyl leukotriene receptor CysLT1 on inflammatory cells in the target organ and that its expression is down-regulated by aspirin desensitization.

METHODS

We obtained nasal-biopsy specimens from 22 aspirin-sensitive and 12 non-aspirin-sensitive patients with chronic rhinosinusitis and nasal polyps. Additional specimens were then obtained from subgroups of the aspirin-sensitive patients after intranasal application of lysine aspirin or placebo for two weeks (five and four patients, respectively) or for six months (five and four patients, respectively). The numbers of leukocytes expressing the CysLT1 and leukotriene B4 (LTB4) receptors per unit area of sections of the nasal submucosa were determined by immunohistochemistry.

RESULTS

The absolute number of cells expressing the CysLT1 receptor was significantly higher in the aspirin-sensitive patients than in the non-aspirin-sensitive patients (median, 542 cells per square millimeter [range, 148 to 1390] vs. 116 cells per square millimeter [range, 40 to 259]; P<0.001). The percentage of CD45+ leukocytes expressing the CysLT1 receptor was also higher in the aspirin-sensitive subjects (25 percent of CD45+ leukocytes [range, 4 to 50] vs. 5 percent of CD45+ leukocytes [range, 2 to 11]; P<0.001); the percentage of CD45+ leukocytes expressing the LTB4 receptor did not differ significantly between these two groups. Desensitization was associated with a decrease in the numbers of inflammatory cells expressing CysLT1.

CONCLUSIONS

The elevated numbers of nasal inflammatory leukocytes expressing the CysLT1 receptor in aspirin-sensitive patients with chronic rhinosinusitis as compared with their non-aspirin-sensitive counterparts and the down-regulation of receptor expression after desensitization to aspirin are probably fundamental in the pathogenesis of aspirin sensitivity and in the mechanism of aspirin desensitization.

Uncoupled regulation of leukotriene C4 synthase in platelets from aspirin-intolerant asthmatics and healthy volunteers after aspirin treatment

BACKGROUND

We have reported that thromboxane A2 induces suppression of leukotriene (LT) C4 synthase activity in human platelets.

AIM

In the present study, we describe a mechanism whereby aspirin treatment can lead to increased formation of LTC4, which is a potent bronchoconstrictor and inflammatory mediator. This mechanism is also demonstrated to be present in platelets from aspirin-intolerant asthmatics (AIA).

METHODS

The effect of arachidonic acid or platelet agonists on LTC4 synthase activity was investigated in platelets obtained from healthy volunteers, aspirin-intolerant asthmatics or aspirin-tolerant asthmatics after in vivo treatment or in vitro pre-incubation with aspirin.

RESULTS

Incubation of normal platelets with arachidonic acid or collagen provoked approximately 50% reduction of platelet LTC4 synthase activity, as determined by the conversion of LTA4 to LTC4. However, the inhibitory effect of arachidonic acid or collagen was not observed after oral administration of aspirin prior to collection of the platelets. Arachidonic acid-induced inhibition of LTC4 synthase activity was totally abolished in platelets collected from peripheral blood already 30 min after aspirin ingestion but was fully restored in platelets collected 3 to 7 days after the administration of aspirin. Treatment of platelet suspensions with aspirin in vitro dose-dependently counteracted the suppressive effect of arachidonic acid on LTC4 formation, with total reversal at approximately 40 microm. In contrast, the major aspirin metabolite, salicylic acid did not alter arachidonic acid-induced reduction of LTC4 synthase activity. Similarly, LTC4 synthase activity in platelets from AIA and aspirin-tolerant asthmatics (ATA) was reduced by approximately 50% after pre-treatment with arachidonic acid in vitro. Again the inhibitory effect was abolished when platelets were pre-incubated in the presence of aspirin.

CONCLUSION

The results indicate that oral aspirin administration can lead to uncoupling of thromboxane A2-dependent negative feedback mechanisms, which may normally restrict the production of cysteinyl leukotrienes. This mechanism can be of potential interest in aspirin-induced asthma.

Aspirin intolerance and nasal polyposis

Chronic rhinosinusitis with nasal polyposis usually develops in aspirin-sensitive patients with asthma Arachidonic acid metabolism appears to be abnormal in the nasal polyps of aspirin-sensitive patients with asthma. These abnormalities an characterized by a low production of prostaglandin E2 (PGE2) and a high release of cysteinyl leukotrienes. Moreover, cyclooxygenase-2 is markedly downregulated in polyps from aspirin-sensitive patients with asthma. This abnormality may explain the low production of PGE2 in nasal polyps and may account for the increased susceptibility to the inhibitory effects of aspirin. Nasal instillation or ingestion of aspirin induces a nasal reaction in most aspirin-sensitive patients with asthma. This reaction is accompanied by the influx of eosinophils and a concomitant increase in cysteinyl leukotrienes, tryptase, and eosinophil cationic protein release. The aspirin nasal challenge is a very safe test with a moderate sensibility and high specificity that can be used in the diagnosis of aspirin intolerance. The similarities in the reaction between the nose and airways in aspirin-sensitive patients provide compelling evidence for common pathogenic mechanisms for nasal polyps, chronic rhinosinusitis, and bronchial asthma.

Increased exhaled cysteinyl-leukotrienes and 8-isoprostane in aspirin-induced asthma

The pathogenesis of aspirin-induced asthma (AIA) has not yet been clearly elucidated, although eicosanoid metabolites appear to play an important role. We hypothesized that levels of eicosanoids in exhaled air condensate are abnormal in patients with AIA and that they change in patients receiving steroid therapy. We measured cysteinyl-leukotrienes (cys-LTs), prostaglandin E(2) (PGE(2)), and leukotriene B(4) (LTB(4)), and also 8-isoprostane as a marker of oxidative stress, by enzyme immunoassay in exhaled breath condensate from patients with AIA (17 steroid naive; mean age, 41 +/- 23 years; FEV(1), 63%pred), 26 patients with aspirin-tolerant asthma (ATA) (11 steroid naive; mean age, 47 +/- 18 years; FEV(1), 69%pred), and 16 healthy subjects (mean age, 45 +/- 17 years; FEV(1), 93%pred). Cys-LTs were significantly higher in steroid-naive patients with AIA compared with steroid-naive patients with ATA and healthy subjects (152.3 +/- 30.4 and 36.6 +/- 7.1 versus 19.4 +/- 2.8 pg/ml; p < 0.05 and p < 0.05, respectively). Steroid-naive patients with AIA also had higher levels of 8-isoprostane than normal subjects (131.8 +/- 31.0 versus 21.9 +/- 4.5 pg/ml; p < 0.05). There were significantly lower levels of both cys-LTs and 8-isoprostanes in steroid-treated patients with AIA. There was no difference in either the PGE(2) or LTB(4) level between the patient groups. This is the first study to show that cys-LTs and 8-isoprostanes are elevated in expired breath condensate of steroid-naive patients with AIA, and that cys-LTs are decreased in steroid-treated patients. Exhaled PGE(2) levels are not reduced, so that it is unlikely that a deficiency of PGE(2) is an important mechanism, whereas exhaled LTB(4) levels are unchanged, indicating an abnormality beyond 5-lipoxygenase.

Decreased apoptosis and distinct profile of infiltrating cells in the nasal polyps of patients with aspirin hypersensitivity

BACKGROUND

Patients with aspirin-hypersensitive rhinosinusitis/asthma suffer from a severe form of hyperplastic rhinosinusitis with recurrent polyposis. We aimed to assess the presence of apoptotic cells in nasal polyps from aspirin-hypersensitive (AH) and aspirin-tolerant (AT) patients with rhinosinusitis as related to the characteristics of local inflammation.

METHODS

Nasal polyps obtained from 16 AH patients and 36 AT patients (17 atopic and 19 nonatopic) were stained for eosinophils and metachromatic cells, and in parallel immunocytochemistry was performed to detect CD45RO+, HLA-DR+, CD8+ and CD68+ positive cells. Apoptotic cells were detected by a nick-end labelling technique, TUNEL.

RESULTS

The density of apoptotic cells in AH polyps (5.5 + 1.5 cells/mm2) was significantly lower as compared to both atopic (18.7 + 3.8 cells/mm2; P < 0.02;) and nonatopic (21.3 + 5.2 cells/mm2; P < 0.01) AT polyps. The number of eosinophils, mast cells, and CD45RO+ cells were significantly increased in AH compared to AT polyps (P < 0.001), and the density of HLA-DR+ cells in AH patients was higher than in nonatopic (P < 0.02), but not in atopic AT patients. While in AH patients the duration of rhinosinusitis correlated inversely with the number of apoptotic cells (r = - 0.67; P < 0.04), in contrast, in AT atopic patients the duration of rhinosinusitis showed positive correlation with apoptosis (r = 0.89; P < 0.003).

CONCLUSIONS

We conclude, that decreased apoptosis of inflammatory cells in nasal polyps from ASA-hypersensitive patients, reflects a distinct mechanisms of local inflammation and may be related to persistence and severity of the disease in these patients.

Possible involvement of mast-cell activation in aspirin provocation of aspirin-induced asthma

BACKGROUND

Although there is increasing evidence of the importance of cysteinyl leukotrienes (LT) as mediators of aspirin-induced bronchoconstriction in aspirin-sensitive asthma, the cellular origin of the LT is not yet clear.

METHODS

Urinary concentrations of leukotriene E4 (LTE4), 11-dehydrothromboxane B2, 9alpha,11beta-prostaglandin F2, and Ntau-methylhistamine were measured during the 24 h following cumulative intravenous administration of increasing doses of lysine aspirin to asthmatic patients. In addition, the urinary concentrations of these metabolites were measured on 5 consecutive days in a patient who suffered an asthma attack after percutaneous administration of nonsteroidal anti-inflammatory drugs.

RESULTS

In aspirin-induced asthma patients (AIA, n=10), the basal concentration of urinary LTE4, but not the other metabolites, was significantly higher than that in aspirin-tolerant asthma patients (ATA, n=10). After intravenous aspirin provocation, the AIA group showed a 13.1-fold (geometric mean) increase in excretion of LTE4 during the first 3 h, and 9alpha,11beta-prostaglandin F2 also increased in the AIA group during the first 0-3 h and the 3-6 h collection period. Ntau-methylhistamine excretion was also increased, but to a lesser degree. Administration of aspirin caused significant suppression of 11-dehydrothromboxane B2 excretion in both the AIA and ATA groups. When the percentage of maximum increase of each metabolite from the baseline concentrations was compared between the AIA group and the ATA group, a significantly higher increase in excretion of LTE4, 9alpha,11beta-prostaglandin F2, and Ntau-methylhistamine was observed in the AIA group than the ATA group. An increased excretion of LTE4 and 9alpha,11beta-prostaglandin F2 has been detected in a patient who suffered an asthma attack after percutaneous administration of nonsteroidal anti-inflammatory drugs.

CONCLUSIONS

Considering that human lung mast cells are capable of producing LTC4, prostaglandin D2, and histamine, our present results support the concept that mast cells, at least, may participate in the development of aspirin-induced asthma.

Increased levels of 12(S)-HETE in patients with essential hypertension

The platelet-type 12-lipoxygenase (12-LO) catalyzes the transformation of arachidonic acid into 12-hydroperoxyeicosatetraenoic acid [12-(S)HPETE], which is reduced to 12-hydroxyeicosatetraenoic acid [12-(S)HETE]. These metabolites exhibit a variety of biological activities such as mediation of angiotensin II-induced intracellular calcium transients in cultured rat vascular smooth muscle cells. It has recently been reported that platelet 12(S)-HETE production is enhanced in the spontaneously hypertensive rat. The pronounced hypotensive effect of LO inhibition in SHR suggests that LO activity may play a role in this form of hypertension. The aim of this study was to determine the basal and thrombin-induced platelet 12(S)-HETE production and the urinary 12(S)-HETE excretion in essential hypertension. We studied 19 patients with this disease (57+/-2 years of age) and 9 normotensive control subjects (48+/-5 years of age) (P:=0.074). 12(S)-HETE was measured in Sep-Pack-extracted samples with specific ELISA and high-performance liquid chromatography. The platelet basal level of 12(S)-HETE was significantly higher in patients than in control subjects (3.56+/-1.22 versus 0.64+/-0.13 ng/10(6) platelets, P:<0.025). In contrast, there were no differences in thrombin-stimulated (1 U/mL) 12(S)-HETE generation: 7.66+/-2.14 in patients versus 4.87+/-1.46 in control subjects (P:=0.61). Platelet 12-LO protein levels, measured by Western blotting with a polyclonal antibody, were higher in the patients than in the control subjects. The urinary excretion of 12(S)-HETE was higher in patients than in control subjects: 36.8+/-7.24 versus 17.1+/-3.14 ng/mg creatinine (P:<0.01). These results indicate that 12(S)-HETE levels and 12-LO protein are increased in patients with essential hypertension, suggesting a role for this metabolite in human hypertension.

Aspirin and asthma

Aspirin is not only one of the best-documented medicines in the world, but also one of the most frequently used drugs of all times. In addition to its role as an analgesic, aspirin is being increasingly used in the prophylaxis of ischemic heart disease and strokes. The prevalence of aspirin intolerance is around 5 to 6%. Up to 20% of the asthmatic population is sensitive to aspirin and other nonsteroidal anti-inflammatory drugs (NSAIDs) and present with a triad of rhinitis, sinusitis, and asthma when exposed to the offending drugs. This syndrome is referred to as aspirin-induced asthma (AIA). The pathogenesis of AIA has implicated both the lipoxygenase (LO) and the cyclooxygenase (COX) pathways. By inhibiting the COX pathway, aspirin diverts arachidonic acid metabolites to the LO pathway. This also leads to a decrease in the levels of prostaglandin (PG) E(2), the anti-inflammatory PG, along with an increase in the synthesis of cysteinyl leukotrienes (LTs). Evidence suggests that patients with AIA have increased activity of LTC(4) synthase, the rate-limiting enzyme in the cysteinyl LT synthesis, in their bronchial biopsy specimens, thereby tilting the balance in favor of inflammation. LT-modifying drugs are effective in blocking the bronchoconstriction provoked by aspirin and are used in the treatment of this condition. Aspirin desensitization has a role in the management of AIA, especially in patients who need prophylaxis from thromboembolic diseases, myocardial infarction, and stroke. This review covers the latest understanding of pathogenesis, clinical features, and management of AIA.

Intranasal challenge with aspirin in the diagnosis of aspirin intolerant asthma: evaluation of nasal response by acoustic rhinometry

BACKGROUND

Nasal provocation tests with lysine-aspirin have recently been introduced for assessment of aspirin intolerant asthma. A study was undertaken to evaluate the usefulness of acoustic rhinometry, a new non-invasive technique, in the diagnosis of aspirin intolerant asthma/rhinitis.

METHODS

Fifteen patients with aspirin intolerant asthma/rhinitis (nine women, mean (SD) age 54.7 (14) years), eight patients with aspirin tolerant asthma/rhinitis (three women, mean (SD) age 52.6 (7.8) years), and eight healthy subjects (two women, mean (SD) age 32.5 (9.7) years) were studied. All subjects were challenged with saline (0.9% NaCl) and 25 mg lysine acetylsalicylic acid (L-ASA) instilled into each nostril of the nose on two separate days. The clinical response was evaluated based on nasal symptoms (sneezes, itching, secretion and blockage). The nasal response was measured by acoustic rhinometry. Symptoms and rhinometry curves were recorded at 10 minute intervals for three hours, one hour before challenge and two hours after challenge.

RESULTS

L-ASA challenge induced a significant increase in symptoms in patients with aspirin intolerant asthma/rhinitis. No differences in the clinical response were detected in those with aspirin tolerant asthma/rhinitis or healthy subjects. L-ASA challenge induced a significant decrease in nasal volume measured by acoustic rhinometry in aspirin intolerant patients. No differences were detected between the challenges in aspirin tolerant patients. If a 25% decrease in nasal volume is taken as the cut off point, the specificity of the test was 94% and the sensitivity reached 73%. The nasal challenge was well tolerated by all subjects.

CONCLUSION

Acoustic rhinometry may be used to study the nasal response to L-ASA. Nasal challenge with L-ASA is safe and can be used as a diagnostic test even in asthmatic patients with severe bronchial obstruction.

15(S)-HETE modulates LTB(4) production and neutrophil chemotaxis in chronic bronchitis

We evaluated the levels of 15(S)-hydroxyeicosatetraenoic acid [15(S)-HETE] and the expression of 15-lipoxygenase (15-LO) mRNA in induced sputum obtained from 10 control and 15 chronic bronchitis subjects. 15(S)-HETE was evaluated by reverse phase high-performance liquid chromatography separation followed by specific RIA. 15-LO mRNA expression was determined by primed in situ labeling. The levels of both soluble and cell-associated 15(S)-HETE resulted significantly higher in chronic bronchitis than in control subjects. The percentage of cells expressing 15-LO mRNA was significantly higher in chronic bronchitis than in control subjects (P < 0.01). Double staining for specific cell type markers and 15-LO mRNA showed macrophages and neutrophils positive for 15-LO, whereas similar staining of peripheral blood neutrophils did not show evidence for 15-LO expression, suggesting that expression of 15-LO in neutrophils takes place on migration into the airways. Because 15(S)-HETE inversely correlated with the percentage of neutrophils in sputum of chronic bronchitis subjects, we studied the effect of 15(S)-HETE on leukotriene B(4) (LTB(4)) production in vitro and evaluated the concentration of LTB(4) in induced sputum and the contribution of LTB(4) to the chemotactic activity of induced sputum samples ex vivo. The results obtained indicate that macrophages and neutrophils present within the airways of chronic bronchitis subjects express 15-LO mRNA; increased basal levels of 15(S)-HETE may contribute to modulate, through the inhibition of 5-lipoxygenase metabolites production, neutrophil infiltration and airway inflammation associated with chronic bronchitis.

Induced sputum inflammatory mediator concentrations in eosinophilic bronchitis and asthma

Eosinophilic bronchitis is a common cause of chronic cough, which like asthma is characterized by sputum eosinophilia, but in contrast to asthma there is no variable airflow obstruction or airway hyperresponsiveness. Our hypothesis was that the differences in airway pathophysiology maybe due to less active airway inflammation in eosinophilic bronchitis, with reduced release of important effector mediators. We measured the concentration of various proinflammatory mediators in induced sputum cell-free supernatant in eight patients with eosinophilic bronchitis, 17 patients with asthma matched for sputum eosinophil count, and 10 normal subjects. Cysteinyl-leukotrienes (cys-LT) were measured by enzyme immunoassay, eosinophilic cationic protein (ECP) by fluoroimmunoassay, prostanoids (PGE(2), PGD(2), TXB(2), and PGF(2alpha)) by gas chromatography-negative ion chemical ionization-mass spectroscopy, and histamine by radioenzymic assay. The geometric mean sputum eosinophil count was similar in asthma (13.4%) and eosinophilic bronchitis (12.5%). Sputum cys-LT and ECP were a mean (95% CI) 1.6-fold (1.1, 2.5) and 6.4-fold (1.4, 28) higher in eosinophilic bronchitis and 1.9-fold (1.3, 2.9) and 7.7-fold (1.2, 46) higher in asthma compared with that in control subjects (geometric mean, 5.9 and 95 ng/ml, respectively). In eosinophilic bronchitis the mean concentration of sputum PGD(2) (0.79 ng/ml) and histamine (168 ng/ml) were significantly higher than in asthma (mean absolute difference in PGD(2) concentration, 0.47 ng/ml [95% CI, 0.19 to 0. 74] and mean-fold difference in histamine concentration, 6.7 [95% CI 1.7 to 26]) and normal subjects (0.64 ng/ml [0.36 to 0.90] and 11-fold [3.3 to 36]), respectively. In conclusion, eosinophilic bronchitis is associated with active airway inflammation with increased release of vasoactive and bronchoconstrictor mediators.

Drug-induced respiratory disorders: incidence, prevention and management

Various drugs are associated with adverse respiratory disorders (ARDs) ranging in severity from mild, moderate to severe and even fatal. Cardioselective and nonselective beta-blockers, calcium antagonists and dipyridamole can induce asthma. ACE inhibitors are mainly associated with cough. Amiodarone is related to a form of interstitial pneumonitis (IP) which can be fatal, tocainidine and flecainidine to a form of IP, and hydrochlorothiazide to a form of IP and pulmonary oedema. Antiasthmatic drugs can be associated with a paradoxical bronchospasm, while leukotriene antagonists are linked to the development of Churg-Strauss syndrome. Nonsteroidal anti-inflammatory drugs including aspirin (acetylsalicylic acid) may induce asthma. Gold is mainly related to IP, penicillamine to IP, systemic lupus erythematosus, bronchiolitis obliterans, and Goodpasture's syndrome. Acute respiratory reactions to nitrofurantoin include dyspnoea, cough, IP, and pleural effusion while IP and fibrosis are common in chronic reactions. Other antibacterials mainly evoke pneumonitis, pulmonary infiltrates and eosinophilia, and bronchiolitis obliterans. ARDs are similar for most categories of cytotoxic agents, with chronic pneumonitis and fibrosis being the most common. Noncardiogenic pulmonary oedema occurs as the most common respiratory complication in opioid agonist addiction. Psychotropic drugs such as phenothiazides, butyrophenones and tricyclic antidepressants can also induce pulmonary oedema. Oral contraceptives may produce asthma exacerbation, while long term use and/or high doses of postmenopausal hormone replacement therapy increase the risk of asthma. Bromocriptine is mainly associated with pleural effusion, while methysergide is usually associated with pleural effusion and fibrosis. Some anorectic agents have been linked to the development of primary pulmonary hypertension. The possibility of the occurrence of ARDs should be taken into account in each individual patient. Although in most cases the adverse effects are unpredictable, they can be reduced to a minimum or prevented if some drugs are avoided or stopped in time.

Sputum cysteinyl leukotrienes increase 24 hours after allergen inhalation in atopic asthmatics

We have used the relatively noninvasive technique of induced sputum to measure allergen-induced changes in the concentration of eicosanoid mediators in bronchial secretions from atopic asthmatics. Sputum induction was performed before and 24 h after inhalational allergen challenge in 14 atopic asthmatics who developed a late asthmatic reaction (LAR). Differential cell counts were made on sputum cytospins and eicosanoid (cysteinyl leukotrienes [cys LTs], prostaglandin D(2) [PGD(2)], and PGE(2)) concentrations were measured in the sputum supernatants. The percentage of eosinophils at baseline correlated with the concentration of cys LTs (r = 0.84, p < 0.001) but not prostanoid mediators. Allergen challenge produced a significant increase in the concentration of sputum cys LTs from 3. 45 ng/ml sputum to 11.95 ng/ml (p = 0.002), which correlated with the increase in sputum eosinophils (r = 0.55, p < 0.05). There were no significant changes in PGD(2) or PGE(2) concentrations in sputum supernatants in response to challenge. Thus, the noninvasive technique of induced sputum has been used to demonstrate increased cys LTs, but not prostanoids associated with LAR after allergen challenge. The correlation between eosinophil numbers and cys LT concentrations at baseline values and 24 h after allergen challenge is consistent with these cells being a principal source of cys LTs within the airways at these time points.

15-Lipoxygenase expression and 15(S)-hydroxyeicoisatetraenoic acid release and reincorporation in induced sputum of asthmatic subjects

BACKGROUND

Recent evidence shows that 15(S)-hydroxy-eicoisatetraenoic acid (15[S]-HETE) can be released and rapidly reincorporated into cellular lipids. These mechanisms exert several immunoregulatory functions that may be relevant in airway inflammation.

OBJECTIVE

Our purpose was to evaluate the levels of both soluble and cell-associated 15(S)-HETE and to examine 15-lipoxygenase (15-LO) messenger RNA (mRNA) expression in sputum samples obtained from 10 control and 18 asthmatic subjects.

METHODS

Levels of 15(S)-HETE were measured by reverse-phase HPLC separation followed by RIA in supernatants and in cell membrane-extracted phospholipids after acid hydrolysis. 15-LO mRNA was evaluated by primed in situ hybridization (PRINS). Combined immunocytochemistry and PRINS was used to identify the phenotype of cells bearing 15-LO transcripts.

RESULTS

Levels of both soluble and cell-associated 15(S)-HETE were higher in asthmatic than in control subjects (P <.0001). The percentage of cells expressing 15-LO mRNA was higher in asthmatic than in control subjects (P <.01). On double staining for specific cell-type markers and 15-LO mRNA, macrophages were the major source for 15-LO.

CONCLUSION

This study shows that the induced sputum technique allows the evaluation of 15-LO activity and that soluble, cell-associated 15(S)-HETE and 15-LO levels are higher in asthmatic than in control subjects. In addition, this study indicates that, in induced sputum, airway macrophages are the major source of 15(S)-HETE in asthma.

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.

Induced sputum eicosanoid concentrations in asthma

Further definition of the role of leukotrienes (LT) and prostaglandins (PG) in asthma would be helped by a noninvasive method for assessing airway production. The supernatant from sputum induced with hypertonic saline and dispersed using dithiotrietol has been successfully used to measure other molecular markers of airway inflammation and might be a useful method. We have measured induced sputum supernatant LTC(4)/D(4)/E(4) concentrations using enzyme immunoassay and PGE(2), PGD(2), TXB(2), and PGF(2alpha) using gas chromatography-negative ion chemical ionization-mass spectroscopy in 10 normal subjects and in 26 subjects with asthma of variable severity. Sputum cysteinyl-leukotrienes concentrations were significantly greater in subjects with asthma (median, 9.5 ng/ml) than in normal control subjects (6.4 ng/ml; p < 0.02) and greater in subjects with persistent asthma requiring inhaled corticosteroids (median, 11.4 ng/ml) or studied within 48 h of an acute severe exacerbation of asthma (13 ng/ml) than in subjects with episodic asthma treated with inhaled beta(2)-agonists only (7.2 ng/ml). There were no significant differences in the concentrations of other eicosanoids between groups, although there was a negative correlation between the percentage sputum eosinophil count and sputum PGE(2) concentration (r = -0.48; p < 0.01) in subjects with asthma. We conclude that induced sputum contains high concentrations of eicosanoids and that sputum LTC(4)/D(4)/E(4) concentrations are significantly greater in subjects with asthma than in normal subjects. The inverse relationship between eosinophilic airway inflammation and sputum PGE(2) concentration would be consistent, with the latter having an anti-inflammatory role.

Means of increasing sensitivity of an in vitro diagnostic test for aspirin intolerance

BACKGROUND

Pseudo-allergic reactions caused by aspirin (acetyl salicylic acid; ASA) often resemble immediate-type hypersensitivity reactions consisting of urticaria and angioedema or rhinoconjunctivitis, asthma and nasal polyps. In the last few years, a new in vitro assay based on determination of sulfidoleucotrienes from isolated leucocytes (cellular allergen stimulation test - CAST) has been introduced for type I allergies and pseudoallergic reactions. In ASA intolerance, there is only limited experience using this assay with - in some studies - only moderate sensitivity. Furthermore, the necessity to use freshly isolated leucocytes from untreated patients is inconvenient for routine settings.

OBJECTIVE

The purpose of our study was to search for possibilities of increasing the sensitivity of the test and to use stored blood samples which would permit shipping, two requirements for the clinical suitability of this test.

PATIENTS AND METHODS

Leucotriene release in response to ASA and other non-steroidal anti-inflammatory drugs (NSAIDs) was analysed in 38 ASA-intolerant patients (predominantly airway-related symptoms n = 22; predominantly cutaneous symptoms n = 16) and 50 controls. The diagnosis of ASA intolerance was established by history and placebo-controlled oral challenge tests.

RESULTS

Using 24 h-stored leucocytes obtained from 10 ASA-intolerant patients and 10 healthy controls there were no significant differences of leucotriene release by resting, ionomycin-, and anti FcepsilonRIalpha-stimulated leucocytes compared with freshly isolated leucocytes. Analysis of ASA + C5a-mediated leucotriene release by stored blood samples in combination with indomethacin- and diclofenac-mediated leucotriene release in ASA-intolerant patients (n = 38) resulted in an increased sensitivity (from 50 to 72.7% in ASA-intolerant patients with predominantly airway-related symptoms and from 81 to 100% in ASA-intolerant patients with predominantly skin symptoms) compared with assays in which only ASA + C5a-mediated leucotriene release has been determined. Moreover, the specificity of the assay remained high (96.7% when analysing different NSAIDs compared with > 99% when analysing only ASA + C5a-mediated leucotriene release).

CONCLUSION

In vitro stimulation with ASA + C5a leucocyte stimulation with other NSAIDs should be performed to achieve a higher sensitivity. This finding can be explained by the clinical observation of a high ratio of cross-reactivities between the mentioned NSAIDs.

Allergic lung responses are increased in prostaglandin H synthase-deficient mice

To investigate the function of prostaglandin H synthase-1 and synthase-2 (PGHS-1 and PGHS-2) in the normal lung and in allergic lung responses, we examined allergen-induced pulmonary inflammation and airway hyperresponsiveness in wild-type mice and in PGHS-1(-/-) and PGHS-2(-/-) mice. Among nonimmunized saline-exposed groups, we found no significant differences in lung function or histopathology, although PGE(2) was dramatically reduced in bronchoalveolar lavage (BAL) fluid from PGHS-1(-/-) mice, relative to wild-type or PGHS-2(-/-) mice. After ovalbumin sensitization and challenge, lung inflammatory indices (BAL cells, proteins, IgE, lung histopathology) were significantly greater in PGHS-1(-/-) mice compared with PGHS-2(-/-) mice, and both were far greater than in wild-type mice, as illustrated by the ratio of eosinophils in BAL fluid (8:5:1, respectively). Both allergic PGHS-1(-/-) and PGHS-2(-/-) mice exhibited decreased baseline respiratory system compliance, whereas only allergic PGHS-1(-/-) mice showed increased baseline resistance and responsiveness to methacholine. Ovalbumin exposure caused a modest increase in lung PGHS-2 protein and a corresponding increase in BAL fluid PGE(2) in wild-type mice. We conclude that (a) PGHS-1 is the predominant enzyme that biosynthesizes PGE(2) in the normal mouse lung; (b) PGHS-1 and PGHS-2 products limit allergic lung inflammation and IgE secretion and promote normal lung function; and (c) airway inflammation can be dissociated from the development of airway hyperresponsiveness in PGHS-2(-/-) mice.

15-HETE-substituted diglycerides selectively regulate PKC isotypes in human tracheal epithelial cells

Human tracheal epithelial (TE) cells selectively incorporate their major lipoxygenase product, 15-hydroxyeicosatetraenoic acid (15-HETE), into the sn-2 position of phosphatidylinositol (PI) (S. E. Alpert and R. W. Walenga. Am. J. Respir. Cell Mol. Biol. 8: 273-281, 1993). Here we investigated whether 15-HETE-PI is a substrate for receptor-mediated generation of 15-HETE-substituted diglycerides (DGs) and whether these 15-HETE-DGs directly activate and/or alter conventional diacylglycerol-induced activation of protein kinase C (PKC) isotypes in these cells. Primary human TE monolayers incubated with 0.5 microM 15-[3H]-HETE or 15-[14C]HETE for 1-2 h were stimulated with 1 nM to 1 microM platelet-activating factor (PAF) for 30 s to 6 min, and the radiolabel in the medium, cellular phospholipids, and neutral lipids was assessed by high-performance liquid and thin-layer chromatography. PAF mobilized radiolabel from PI in a dose-dependent manner (22 +/- 5% decrease after 1 microM PAF) without a concomitant release of free intra- or extracellular 15-HETE. 14C-labeled DGs were present in unstimulated TE monolayers incubated with 15-[14C]HETE, and the major 14C band, identified as sn-1,2-15-[14C]HETE-DG, increased transiently in response to PAF. Western blots of freshly isolated and cultured human TE cells revealed PKC isotypes alpha, betaI, betaII, delta, epsilon, and zeta. In vitro, cell-generated sn-1, 2-15-[14C]HETE-DG selectively activated immunoprecipitated PKC-alpha and inhibited diacylglycerol-induced activation of PKC-alpha, -delta, -betaI, and -betaII. Our observations indicate that 15-HETE-DGs can modulate the activity of PKC isotypes in human TE cells and suggest an intracellular autocrine role for 15-HETE in human airway epithelia.

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.

Cyclooxygenase-2 mRNA is downexpressed in nasal polyps from aspirin-sensitive asthmatics

Exogenous prostaglandin E2 (PGE2) given by inhalation almost completely abrogates aspirin-induced asthma and the accompanying increase in cysteinyl-leukotrienes production. Cyclooxygenase (COX) may be present in cells in both constitutive (COX-1) and inducible (COX-2) forms. To increase the production of the potentially protective endogenous PGE2, COX-2 should be upregulated. We hypothesize that an abnormal regulation of COX-2 will predispose patients with asthma to develop aspirin-intolerant asthma/rhinitis (AIAR). We therefore examined the expression of COX-2 messenger RNA (mRNA) in healthy nasal mucosa (n = 11) and in nasal polyps from both patients with AIAR (n = 8) and those with aspirin-tolerant asthma/rhinitis (ATAR) (n = 20). After total mRNA extraction, COX-1 and COX-2 mRNA expression were measured using a reverse transcriptase (RT)-semiquantitative PCR technique. Hybrid primers of COX-1. glyceraldehyde-3-phosphate dehydrogenase (GAPDH) or COX-2. GAPDH were used to create PCR products that were cloned and used as internal standard controls in the competitive PCR reaction. Results are presented as mean +/- standard error of 10(6) molecules of mRNA/micrograms of total RNA. No differences in COX-1 mRNA expression were found between nasal mucosa and nasal polyps from both patients with ATAR and those with AIAR. However, COX-2 mRNA expression in nasal polyps from the AIAR group (0.38 +/- 0.10) was markedly and significantly lower than in polyps from the ATAR group (2.93 +/- 0. 52, sevenfold, p < 0.0001) and nasal mucosa (2.10 +/- 0.54, sixfold, p < 0.01). These findings suggest that an inadequate COX-2 regulation may be involved in AIAR.

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.

Novel polymorphism of the 5-lipoxygenase activating protein (FLAP) promoter gene associated with asthma

The human 5-lipoxygenase activating protein (FLAP) gene is one of the key genes involved in the production of the cysteinyl-leukotrienes. We studied novel polymorphism of the FLAP promoter gene and attempted to clarify the relationship between this polymorphism and asthma. We sequenced the FLAP promoter region, containing the -170 to +46-bp sequence from the translational start codon, and found two homozygotes of novel alleles in the polyadenyl region which showed 21 A repeats and 18 A repeats, respectively. The frequency of the 21 A repeats was 52/71 (73.2%) in asthmatics and 39/71 (54.9%) in control subjects. The difference between these frequencies was statistically significant (P = 0.035). This is the first report of FLAP promoter gene polymorphism associated with asthma. Our data suggest that FLAP promoter gene polymorphism might play a crucial role in the pathogenesis of asthma.

Analyses of prostaglandin D2 metabolites in urine: comparison between enzyme immunoassay and negative ion chemical ionisation gas chromatography-mass spectrometry

Measurements of the prostaglandin (PGD2) metabolite 9 alpha, 11 beta-PGF2 in unextracted urine performed by enzyme immunoassay (EIA) were compared with values obtained by negative chemical ionisation gas chromatography-mass spectrometry (NCI GC-MS). Values determined by NCI GC-MS were in the same range but consistently lower than those obtained by EIA, suggesting that other endogenous compounds could be contributing to the immunoreactivity. Isoprostanes were generated by autoxidation of arachidonic acid and the 9 alpha, 11 beta-PGF2 antibody demonstrated less than 0.7% crossreactivity to the mix, making it unlikely that isoprostanes in urine interfere with quantification of 9 alpha, 11 beta-PGF2 by EIA. This was further supported by the 70% reduction in immunoreactive material measured in urine after three days treatment in a healthy volunteer with the cyclooxygenase inhibitor ibuprofen. Purification of urine samples by reverse phase high-performance liquid chromatography (HPLC) revealed the presence of two immunoreactive compounds in addition to 9 alpha, 11 beta-PGF2. The compounds were identified as dinor compounds by NCI GC-MS. One of the compounds was identical to 9 alpha, 11 beta-2,3-dinor-PGF2 which was generated by beta-oxidation of 9 alpha, 11 beta-PGF2 and identified by electron impact (EI)-GC-MS. In conclusion, urinary 9 alpha, 11 beta-PGF2 concentrations measured by EIA represent the sum of 9 alpha, 11 beta-PGF2 and two isomers of its dinor metabolite. Thus, the direct EIA is fast, sensitive and sufficiently specific to monitor activation of the PGD2 pathway, thereby providing a valuable clinical tool to assess the status of mast cell activation in vivo.

Arachidonic acid metabolism in nasal tissue and peripheral blood cells in aspirin intolerant asthmatics

Aspirin intolerance (AI) is characterized by polypous rhinosinusitis, bronchial asthma and adverse reactions to aspirin. The common intolerance to all cyclo-oxygenase inhibitors allows us to focus study of the pathogenesis of AI on the metabolism of arachidonic acid (AA). We studied the metabolism of AA in nine aspirin intolerant asthmatics (AIA) and eight healthy volunteers (controls) by measuring prostaglandin E2 (PGE2) and peptido-leukotrienes (pLT = LTC4/D4/E4) in nasal tissue and peripheral blood cells (PBCs) using a specific immunoassay. In all patients with AI the tests were performed before and after bronchial provocation with lysine-ASA. In the control group the tests were done before and after 500 mg ASA p.o. The release of pLT in nasal polyps of AIA was found to be significantly higher than in normal mucosa of AIAs and controls. In every tissue a significant increase of pLT after aspirin challenge was observed. Nasal polyps of AIA show a significantly lower release of PGE2 than normal mucosa of AIAs and controls. Peripheral blood cells of AIA show a significantly higher release of pLT and a significantly lower release of PGE2 than PBCs of controls. Therefore clinical manifestations of AI may be based on an alteration of AA metabolism in AIA.

Expression of 5-lipoxygenase and 5-lipoxygenase-activating protein mRNAs in the peripheral blood leukocytes of asthmatics

Leukotrienes are a family of arachidonic acid metabolites with potent biological activities such as bronchoconstriction and leukocyte chemotaxis. Recent evidence has demonstrated that the 5-lipoxygenase (5-LO) and 5-lipoxygenase-activating protein (FALP) products of arachidonic acid metabolism, leukotriene C4, D4 and E4, were increased in the serum and the urine of asthmatic patients. Therefore, we examined the expression of 5-LO and FLAP mRNAs in the peripheral blood leukocytes (PBL) of 10 asthmatics and 10 controls. Both 5-LO and FLAP mRNAs of PBL in the asthmatic group were found to be significantly increased compared with those in the control group. These data suggest that up-regulation of 5-LO and FLAP mRNAs might be involved in the increased leukotriene synthesis and play an important role in the pathogenesis of asthma.

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.

Cromolyn sodium prevents bronchoconstriction and urinary LTE4 excretion in aspirin-induced asthma

BACKGROUND

Inhalation of cromolyn sodium protects against sulpyrine-induced bronchoconstriction and prevents urinary leukotriene E4 (u-LTE4) excretion in aspirin-induced asthma.

OBJECTIVE

This study was designed to investigate the protective effect of cromolyn sodium on airway responsiveness to the sulpyrine provocation test, and to investigate whether this protective activity is associated with a reduction in aspirin-induced urinary excretion of LTE4, a marker of the cysteinyl leukotriene overproduction that participates in the pathogenesis of aspirin-induced asthma.

METHODS

We evaluated the effects of pretreatment with cromolyn sodium on bronchoconstriction precipitated by inhalation of sulpyrine in ten adult patients with mild aspirin-induced asthma. Those who were in stable clinical condition and were hyperresponsive to sulpyrine provocation test were allocated to this study. Urinary leukotriene E4 was measured using combined reverse phase high performance liquid chromatography (rp-HPLC)/enzyme immunoassay.

RESULTS

Inhaled cromolyn sodium protects against aspirin-induced attacks of asthma through mechanisms not related to the bronchodilator property, but related to the improvement of the bronchial hypersensitivity, almost completely in all patients (P < .001). By contrast, after cromolyn sodium the maximum level of u-LTE4 was significantly lower than control (P < .05).

CONCLUSION

Our results suggest for the first time that inhaled cromolyn sodium is one of the most useful inhibitors of aspirin-induced bronchoconstriction, probably acting by inhibiting the release of cysteinyl leukotrienes, and possibly other chemical mediators, by bronchial inflammatory cells.

Expression of interleukin-5 and granulocyte-macrophage colony-stimulating factor in aspirin-sensitive and non-aspirin-sensitive asthmatic airways

Increased numbers of eosinophils and mast cells in the bronchial mucosa are characteristic features in subjects with aspirin-sensitive asthma. Interleukin-5 (IL-5) and granulocyte-macrophage colony-stimulating factor (GM-CSF) are involved in the activation, maturation, and perpetuation of survival of eosinophils. Immunohistochemical techniques were therefore used to study the expression of IL-5 and GM-CSF on frozen bronchial biopsies from 13 aspirin-sensitive asthmatic (ASA) and 8 non-ASA (NASA) subjects. Aspirin sensitivity was diagnosed by lysine-aspirin inhalation provocation. ASA airways demonstrated a significant 2-fold increase in the total number of submucosal inflammatory cells expressing IL-5 (p = 0.03) and approximate 4- and 2-fold increases in the numbers of mast cells expressing IL-5 and GM-CSF (p = 0.02 and p = 0.04, respectively). There was also a 4-fold increase in the number of eosinophils expressing IL-5 (p = 0.004). These results suggest a central role for the mast cell and eosinophil in regulation of the inflammatory cell infiltrate of ASA airways by secretion of the hemopoietic cytokines IL-5 and GM-CSF.

Enhanced expression of cyclo-oxygenase isoenzyme 2 (COX-2) in asthmatic airways and its cellular distribution in aspirin-sensitive asthma

BACKGROUND

There are two isoforms of cyclo-oxygenase (COX), namely COX-1 and COX-2. COX-1 is constitutively expressed in most tissues and in blood platelets. The metabolites derived from COX-1 are probably involved in cellular housekeeping functions. COX-2 is expressed only following cellular activation by inflammatory stimuli and is thought to be involved in inflammation.

METHODS

The expression of COX-1 and COX-2 isoenzymes has been studied in the bronchial mucosa of 10 normal and 18 asthmatic subjects, 11 of whom had aspirin-sensitive asthma (ASA) and seven had non-aspirin-sensitive asthma (NASA) RESULTS: There was a significant fourfold and 14-fold increase, respectively, in the epithelial and submucosal cellular expression of COX-2, but not of COX-1, in asthmatic patients. There was no significant difference in the total number of cells staining for either COX-1 or COX-2 between subjects with ASA and NASA, but the number and percentage of mast cells that expressed COX-2 was significantly increased sixfold and twofold, respectively, in individuals with ASA. There was a mean fourfold increase in the percentage of COX-2 expressing cells that were mast cells in subjects with ASA and the number of eosinophils expressing COX-2 was increased 2.5-fold in these subjects.

CONCLUSION

COX-2-derived metabolites may play an essential part in the inflammatory processes present in asthmatic airways and development of drugs targeted at this isoenzyme may have therapeutic potential in the treatment of asthma. Mast cells and eosinophils may also have a central role in the pathology of aspirin-sensitive asthma.