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

Selection of aspirin dosages for aspirin desensitization treatment in patients with aspirin-exacerbated respiratory disease

BACKGROUND

Aspirin desensitization followed by daily aspirin therapy is effective add-on treatment for patients with aspirin-exacerbated respiratory disease. Prior studies used 650 mg of aspirin twice daily, but studies at lower dosages were inconclusive.

OBJECTIVE

We sought to determine the optimal daily dosage of aspirin treatment.

METHODS

We studied 137 patients who had undergone successful aspirin desensitization and randomized them into 2 groups, 650 mg twice daily versus 325 mg twice daily. After 1 month, patients either increased or decreased their dosage based on their symptom control and continued that dosage for the remainder of the year.

RESULTS

Patients taking either 650 mg twice daily or 325 mg twice daily showed significant improvements in number of sinus infections, sinus operations, and hospitalizations for asthma (all P < .0001). Anosmia, nasal/sinus symptoms, and asthma symptoms also improved in both groups (all P < .03). Systemic corticosteroid dosages decreased by 3- and 4-fold in the 325 mg twice daily and 650 mg twice daily groups, respectively. Of the 137 patients, 32 had adverse effects from or discontinued aspirin therapy: 14 (44%) of 32 from the group randomized to taking 650 mg twice daily and 18 (56%) of 32 from the group randomized to 325 mg twice daily. The most common adverse effect was dyspepsia.

CONCLUSION

Both dosages were efficacious, and side effects occurred in both groups at similar frequencies. Some patients initially taking 325 mg twice daily required an increase to 650 mg twice daily for optimal symptom control.

CLINICAL IMPLICATIONS

We recommend that patients begin daily aspirin therapy with 650 mg twice daily and subsequently decrease to the lowest effective dosage (usually 325 mg twice daily).

Peroxisome proliferator-activated receptor alpha-independent effects of peroxisome proliferators on cysteinyl leukotriene production in mast cells

The effects of peroxisome proliferators, the ligands of a nuclear receptor peroxisome proliferator-activated receptor (PPAR) alpha, on cysteinyl leukotriene production were investigated in rodent mast cells. Peroxisome proliferators Wy-14,643 (30 microM) and fenofibrate (100 microM) significantly inhibited the cysteinyl leukotriene production that was induced by antigen (Ag) treatment after overnight sensitization to Ag specific immunoglobulin E (IgE) in a rat basophilic leukemia (RBL)-2H3 mast cell line. Similar inhibition by these drugs was observed in IgE and Ag-treated mouse bone marrow-derived mast cells, A23187-treated RBL-2H3 and A23187-treated mouse peritoneal macrophages. Wy-14,643 (30 microM) and fenofibrate (100 microM) did not affect the release of radioactivity from RBL-2H3 pre-incubated with [(3)H]-arachidonic acid, which is considered an index of phospholipase A(2) activity. Wy-14,643 (30 microM) and fenofibrate (100 microM) did not directly inhibit 5-lipoxygenase activity. Troglitazone was found to directly inhibit the activity of 5-lipoxygenase. The PPARalpha mRNA level was at less than the limit of detection for the realtime polymerase chain reaction both in RBL-2H3 and bone marrow-derived mast cells. Wy-14,643 (30 microM) and fenofibrate (100 microM) did not induce acyl-CoA oxidase mRNA in RBL-2H3, which was reported to be induced by peroxisome proliferators via PPARalpha in hepatocytes. Wy-14,643 (30 microM) and fenofibrate (100 microM) inhibited the cysteinyl leukotriene production in bone marrow-derived mast cells from PPARalpha-null mice. It was concluded that the inhibitory effects of these peroxisome proliferators on cysteinyl leukotriene production are independent of PPARalpha in mast cells.

Applying pharmacogenomics to enhance the use of biomarkers for drug effect and drug safety

Pharmacogenomics is used to improve patient outcome by maximizing the likelihood of desired effects and minimizing the risk of adverse events using an individual's genetic profile. As such, pharmacogenomics can be used to improve current risk-management strategies (improving the risk-benefit balance). Two areas of great promise for pharmacogenomics in this regard are emerging: (i) the pharmacogenomics of modulating disease biomarkers (to provide insight into novel mechanisms of drug response and to identify the patients most likely to respond to a drug in a favorable way); and (ii) using pharmacogenomics to enhance drug safety. Given that novel biomarkers could enable the earlier detection of many diseases and more-widespread therapies for primary prevention, pharmacogenomics provides the opportunity to identify the patients most likely to respond to these therapies, thereby preserving valuable health-care resources. The use of pharmacogenomics in pharmacovigilance could also be useful for risk-stratifying patients and for helping to identify the mechanisms involved in adverse events.

Asthma: defining of the persistent adult phenotypes

The common disease asthma is probably not a single disease, but rather a complex of multiple, separate syndromes that overlap. Although clinicians have recognised these different phenotypes for many years, they have remained poorly characterised, with little known about the underlying pathobiology contributing to them. Development of targeted therapies for asthma, and phenotype-specific clinical trials have raised interest in these phenotypes. Improved understanding of these phenotypes in complex diseases such as asthma will also improve our ability to link specific genotypes to their associated disease, which should help development of biomarkers. However, there is no standardised method to define asthma phenotypes. This Review analyses some of the methods that have been used to define asthma phenotypes and proposes an integrated method of classification to improve our understanding of these phenotypes.

Treatment of asthma with antileukotrienes: first line or last resort therapy?

Twenty five years after the structure elucidation of slow reacting substance of anaphylaxis, antileukotrienes are established as a new therapeutic modality in asthma. The chapter reviews the biochemistry and pharmacology of leukotrienes and antileukotrienes with particular focus on the different usage of antileukotrienes for treatment of asthma and rhinitis in Europe and the US. Further research needs and new areas for leukotriene involvement in respiratory diseases are also discussed.

The broken balance in aspirin hypersensitivity

Aspirin was introduced into medicine over a century ago and has become the most popular drug in the world. Although the first hypersensitivity reaction was described soon after aspirin had been marketed, only recently a phenomenon of cysteinyl leukotriene overproduction brought new insights on a balance between pro- and anti-inflammatory mediators derived from arachidonic acid. We describe the most common clinical presentations of aspirin hypersensitivity, i.e. aspirin-induced asthma, rhinosinusitis and aspirin-induced urticaria. We also present their biochemical background. Despite relatively high incidence of these reactions, aspirin hypersensitivity remains underdiagnosed worldwide. Acute reactions of aspirin hypersensitivity are elicited via cyclooxygenase inhibition by non-steroid anti-inflammatory drugs. Coxibs, selective inhibitors of cyclooxygenase-2 isoenzyme, do not precipitate symptoms in susceptible patients. Though hypersensitivity correlates with cyclooxygenase-1 inhibition, diminished tissue expression was described only for cyclooxygenase-2. Aspirin-induced asthma and aspirin-induced urticaria, in a substantial part of the patients, are driven by a release of mediators from activated mast cells. These cells in physiological conditions are under inhibitory control of prostaglandin E2. The origin of aspirin hypersensitivity remains unknown, but accumulating data from genetic studies strongly suggest that environmental factor, possibly a common viral infection, can trigger the disease in susceptible subjects.

Pathogenesis and management of aspirin-intolerant asthma

In 2-23% of adults with asthma, and rarely in children with asthma, aspirin (acetylsalicylic acid) and non-steroidal anti-inflammatory drugs (NSAIDs) cause asthma exacerbations. Within 3 hours of ingestion of aspirin/NSAIDs, individuals with aspirin-intolerant asthma (AIA) develop bronchoconstriction, often accompanied by rhinorrhea, conjunctival irritation, and scarlet flush. In severe cases, a single therapeutic dose of aspirin/NSAIDs can provoke violent bronchospasm, loss of consciousness, and respiratory arrest. In order to diagnose AIA, oral, inhaled, nasal or intravenous aspirin challenge tests are performed in facilities where experienced physicians are present and emergency treatment is available. The exact differences in the pathogenesis of AIA and other types of asthma are not fully understood. The interference of aspirin/NSAIDs with arachidonic acid metabolism in the lungs plays an important role in the mechanism of AIA; inhibition of cyclo-oxygenase is accompanied by overproduction of cysteinyl leukotrienes (cys-LTs). It has been proposed that overproduction of cys-LTs, together with removal by aspirin/NSAIDs of the 'brake' imposed by the bronchodilator prostaglandin E2, may cause an asthma attack in patients with AIA. Development of a suitable animal model to investigate the pathogenesis of AIA would help to clarify this question. Although it is still controversial whether leukotriene modifiers are more effective in patients with AIA compared with other types of asthma, because LT plays an important role in the pathogenesis of AIA, leukotriene modifiers are the preferred medication for the long-term control of AIA. Add-on efficacy of leukotriene modifiers has been confirmed in patients with AIA already treated with inhaled corticosteroids. However, this does not mean that aspirin/NSAIDs can be safely taken by aspirin-sensitive patients treated with leukotriene modifiers. To prevent attacks of AIA, sensitive patients should avoid the use of aspirin/NSAIDs or use selective cyclo-oxygenase 2 inhibitors when required. When patients with AIA need aspirin for specific situations they should receive aspirin desensitization therapy or treatment with selective cyclo-oxygenase 2 inhibitors.

Potential New Avenues of Treatment for Chronic Rhinosinusitis: an Anti-inflammatory Approach

Chronic rhinosinusitis is a complex disease process, one that is characterized by much more than just infection. Until its pathophysiology is understood fully, truly definitive therapy may remain elusive. As this underlying inflammatory process begins to unravel, however, new avenues of therapy will begin to emerge. This article discusses some of these new therapies and provides some clues as to where future avenues may go.

Mechanism of chronic urticaria exacerbation by aspirin

In some patients with chronic idiopathic urticaria (CIU), aspirin and other nonsteroidal anti-inflammatory drugs (NSAIDs) that inhibit cyclooxygenase 1 (COX-1) precipitate wheals and swelling. There is no in vitro diagnostic, and diagnosis can be established only by provocation challenges with aspirin or other NSAIDs. Skin reactions triggered by aspirin are associated with the inhibition of cyclooxygenase, specifically COX-1, but not COX-2, and are characterized by overproduction of cysteinyl leukotrienes (cys-LTs). Aspirin and other NSAIDs should be avoided, but highly specific COX-2 inhibitors, known as coxibs, are well tolerated and can probably be safely used. Evidence has been accumulated that these reactions are due to the interference of aspirin-like drugs with arachidonic-acid metabolism. In this article, we discuss the mechanism of these reactions, and the characteristic course of aspirin-induced urticaria and its management.

Aspirin sensitivity and severity of asthma: Evidence for irreversible airway obstruction in patients with severe or difficult-to-treat asthma

BACKGROUND

Patients with aspirin sensitivity experience hyperplastic sinusitis and nasal polyposis. We speculated that similar mechanisms could be acting in the lower airway and that these individuals would demonstrate more severe asthma and irreversible loss of lung function.

OBJECTIVE

We sought to investigate the role of aspirin-exacerbated respiratory disease (AERD) as a risk factor for the development of irreversible airway obstruction.

METHODS

The Epidemiology and Natural History of Asthma: Outcomes and Treatment Regimens (TENOR) study is a multicenter observational study of subjects with severe or difficult-to-treat asthma. Data were compared between subjects who reported asthma exacerbation after aspirin ingestion and those who did not. The primary measure of bronchodilator-resistant obstruction (possible remodeling) was the maximally achieved postbronchodilator spirometry averaged over the 3-year duration of the study.

RESULTS

Adult subjects (>/=18 years) with AERD (n = 459) were compared with subjects with non-aspirin-sensitive asthma (n = 2848). Subjects with AERD had significantly lower mean postbronchodilator percent predicted FEV(1) compared with subjects with non-aspirin-sensitive asthma (75.3% vs 79.9%, P < .001). Differences in spirometry between the 2 cohorts persisted after controlling for potential confounding variables. In addition, subjects with AERD were more likely to have severe asthma by means of physician assessment (66% vs 49%, P < .001), to have been intubated (20% vs 11%, P < .001), to have a steroid burst in the previous 3 months (56% vs 46%, P < .001), and to have required high-dose inhaled corticosteroids (34% vs 26%, P < .001).

CONCLUSIONS

These data suggest that aspirin sensitivity is associated with increased asthma severity and possible remodeling of both the upper and lower airways.

Relation between bronchial responsiveness to inhaled leukotriene D4 and markers of leukotriene biosynthesis

BACKGROUND

While clinical trials with antileukotrienes have shown overall beneficial effects in asthma, the factors that determine leukotriene dependent asthma are still unclear. A study was undertaken to determine whether or not leukotriene responsiveness in the airways correlates with endogenous leukotriene biosynthesis.

METHODS

Bronchial responsiveness to leukotriene (LT) D4 was assessed as PD20FEV1 in 20 subjects with mild asthma and 10 healthy controls, and compared with bronchial responsiveness to methacholine and two global measures of leukotriene production-urinary LTE4 and ex vivo production of LTB4 in whole blood.

RESULTS

In patients with asthma the bronchoconstrictor activity of LTD4 was about 1300 times greater than methacholine (geometric mean PD20 0.69 nmol v 887 nmol). Those who were most responsive to LTD4 were relatively less responsive to methacholine (p<0.01). There was, however, no correlation between bronchial responsiveness to LTD4 and urinary LTE4 or blood ex vivo LTB4 levels in asthmatic subjects or healthy controls. Subjects with asthma treated with inhaled corticosteroids produced higher levels of LTB4 (p<0.05).

CONCLUSIONS

General measures of leukotriene production cannot predict bronchial responsiveness to LTD4. The unique bronchoconstrictive potency of LTD4 on human airways may relate to the locally regulated expression of the cysteinyl LT1 receptor.

Effects of 5-lipoxygenase inhibitor zileuton on airway responses to inhaled swine house dust in healthy subjects

BACKGROUND

Inhalation of swine house dust induces acute airway inflammation and increased bronchial responsiveness in healthy subjects.

OBJECTIVE

The aim of the study was to investigate whether 5-lipoxygenase products such as leukotrienes may have a role in this reaction.

METHODS

Twenty-three healthy subjects were randomised into two groups receiving treatment with either zileuton (600 mg) or placebo four times a day. After 5 days of treatment, all subjects were exposed for 3h in a swine barn. Bronchial responsiveness, exhaled nitric oxide (NO), and mediators in nasal lavage (NAL), blood and urine were measured before and after the exposure.

RESULTS

The exposure induced an increased bronchial responsiveness to methacholine in both groups with 2-3 doubling concentration steps, no significant difference between treatments. Leukotriene E(4) in urine increased significantly following exposure in the placebo group from 37.3 (29.1-45.6) (mean (95% confidence interval)) ng/mmol creatinine to 47.7 (36.3-59.0) ng/mmol creatinine (P<0.05), but not in the zileuton group. The post-exposure increase of LTB(4) levels in NAL fluid was totally abolished in the zileuton group (P<0.05 vs. the placebo). The levels of exhaled NO increased significantly (P<0.01), two-fold in both groups. The PGD(2) metabolite 9alpha, 11beta-PGF(2) increased in placebo-treated subjects (P<0.01; P<0.05 vs. zileuton), strengthening mast cell participation. Neutrophil counts and levels of IL-6 in peripheral blood increased in both groups, with a significantly larger increase in zileuton treated subjects (P<0.05 and P<0.001, respectively compared to placebo).

CONCLUSIONS

Pre-treatment with clinically recommended doses of the 5-lipoxygenase inhibitor zileuton did not affect the increase of bronchial reactivity induced by swine dust exposure. The intervention totally abolished the LTB(4) release in NAL fluid, but only partially inhibited the formation of leukotrienes as monitored by urinary levels. The enhanced increase of neutrophils and IL-6 in peripheral blood in the zileuton group, suggests that inhibition of 5-lipoxygenase may have pro-inflammatory effects.

Polymorphism of tandem repeat in promoter of 5-lipoxygenase in ASA-intolerant asthma: a positive association with airway hyperresponsiveness

BACKGROUND

5-Lipooxygenase (ALOX5) and 5-lipoxygenase-activating protein (ALOX5AP) are known as key enzymes in cysteinyl-leukotriene (cys-LT) production, critical mediators in aspirin acetylsalicyclic acid (ASA)-intolerant asthma (AIA). To date, studies of the promoter region of ALOX5 gene has revealed the potential influence of a variable number of tandem repeats of a Sp1- and Egr1-binding motif, on the transcription rate.

METHODS

To understand the pathological process that arises from cys-LT overproduction in AIA, we genotyped ALOX5 Sp1 and ALOX5AP poly(A) repeat promoter polymorphism by fluorescent-based capillary electrophoresis in the Korean population.

RESULTS

No significant differences in allele and genotype frequencies of the ALOX5 and ALOX5AP promoter polymorphisms were observed between the three groups. However, there was a strong association of the ALOX5 Sp1 repeat polymorphism with airway hyperresponsiveness (AHR; PC20 methacholine); AIA patients carrying a mutant allele (n > 5 or n < 5 repeats) showed increased AHR compared to AIA patients with wild-type genotype (P=0.003).

CONCLUSION

Although the alleles of the ALOX5 and ALOX5AP promoter cannot be considered as a prominent risk factor in the development of AIA, the genetic variant of tandem repeat (GGGCGG; Sp1-binding motif) in ALOX5 promoter is associated with the severity of airway hyperresponsiveness in AIA patients.

Chronic hyperplastic eosinophilic sinusitis as a predictor of aspirin-exacerbated respiratory disease

BACKGROUND

Aspirin-exacerbated respiratory disease (AERD) is a disease of intense eosinophilic inflammation that can produce fibrosis, hyperplasia, and remodeling.

OBJECTIVE

To investigate the usefulness of quantifying severity of chronic hyperplastic eosinophilic sinusitis in predicting the presence of AERD.

METHODS

Data were compared between asthmatic patients who reported exacerbations after aspirin ingestion and those who did not. The primary outcome measure was severity of sinusitis using a validated computed tomography (CT) scan-based scoring system. Indices of lower airway remodeling and other markers of inflammation were also evaluated.

RESULTS

Twenty-one patients with AERD were compared with 19 patients with aspirin-tolerant asthma (ATA). Patients were well matched for asthma severity as shown by their similar lung function as measured by postbronchodilator forced expiratory volume in 1 second. Patients with AERD were distinguished by their sinus CT scores (AERD patients: 16.9; 95% confidence interval [CI], 13.4-21.3; ATA patients: 6.2; 95% CI, 4.2-9.1; P < .001), and they were considerably more likely to have nasal polyps (AERD patients: 90%; ATA patients: 26%; P < .001). In addition, AERD patients demonstrated increased total lung capacity (AERD patients: 107.9%; 95% CI, 99.9%-117.6%; ATA patients: 98.0%; 95% CI, 93.7%-102.5%; P = .05), reflecting a trend toward increased air trapping. No significant differences occurred in diffusing capacity, exhaled nitric oxide, eosinophilia, or exhaled breath condensate pH.

CONCLUSIONS

AERD can be distinguished from ATA by the extent of hyperplasia on CT scan and the presence of nasal polyps. We hypothesize that AERD represents a remodeling process that affects both the upper and lower airways.

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.

Ibuprofen and increased morbidity in children with asthma: fact or fiction?

NSAIDs are commonly avoided by patients with aspirin-induced asthma based on the premise that there is a significant cross-reactivity between aspirin and other NSAIDs. However, ibuprofen, a NSAID sold over the counter in most countries, is commonly given to children for relief of fever and mild-to-moderate pain. Consequently, increased risk of acute bronchospasm induced by ibuprofen in children with asthma remains a persistent concern. More recently, the assumption that children with asthma are at a greater risk for exacerbations of their disease if they take ibuprofen has been questioned. There is little evidence to measurably increases morbidity in the great majority of children with asthma. In addition, recent evidence suggest that ibuprofen measurably increases morbidity in the great majority of [corrected] children with asthma. Given the infrequent occurrence of aspirin/NSAID sensitivity in children with asthma, it seems reasonable to allow the use of ibuprofen in this population unless there is a personal or family history of aspirin-induced asthma. In addition, the inflammatory pathogenesis of asthma, anti-inflammatory effect of ibuprofen, and evidence suggesting ibuprofen may reduce morbidity in children with asthma raises the intriguing possibility that ibuprofen might actually have therapeutic benefit for at least some children with asthma.

Aspirin-induced asthma: clinical aspects, pathogenesis and management

Aspirin (acetylsalicylic acid)-induced asthma (AIA) consists of the clinical triad of asthma, chronic rhinosinusitis with nasal polyps, and precipitation of asthma and rhinitis attacks in response to aspirin and other NSAIDs. The prevalence of the syndrome in the adult asthmatic populations is approximately 4-10%. Respiratory disease in these patients may be aggressive and refractory to treatment. The aetiology of AIA is complex and not fully understood, but most evidence points towards an abnormality of arachidonic acid (AA) metabolism. Cyclo-oxygenase (COX), the rate-limiting enzyme in AA metabolism, exists as two main isoforms. COX-1 is the constitutive enzyme responsible for synthesis of protective prostanoids, whereas COX-2 is induced under inflammatory conditions. A number of theories regarding its pathogenesis have been proposed. The shunting hypothesis proposes that inhibition of COX-1 shunts AA metabolism away from production of protective prostanoids and towards cysteinyl leukotriene (cys-LT) biosynthesis, resulting in bronchoconstriction and increased mucus production. The COX-2 hypothesis proposes that aspirin causes a structural change in COX-2 that results in the generation of products of the lipoxygenase pathway. It is speculated that this may result in the formation of mediators that cause respiratory reactions in AIA. Related studies provide evidence for abnormal regulation of the lipoxygenase pathway, demonstrating elevated levels of cys-LTs in urine, sputum and peripheral blood, before and following aspirin challenge in AIA patients. These studies suggest that cys-LTs are continually and aggressively synthesised before exposure to aspirin and, during aspirin-induced reactions, acceleration of synthesis occurs. A genetic polymorphism of the LTC4S gene has been identified consisting of an A to C transversion 444 nucleotides upstream of the first codon, conferring a relative risk of AIA of 3.89. Furthermore, carriers of the C444 allele demonstrate a dramatic rise in urinary LTE(4) following aspirin provocation, and respond better to the cys-LT antagonist pranlukast than A444 homozygotes.AIA patients have an aggressive form of disease, and treatment should include combination therapy with inhaled corticosteroids, beta(2)-adrenoceptor agonists and LT modifiers. Furthermore, recently developed inhibitors of COX-2 may be safer in patients with AIA.

Alternative medical treatment strategies for chronic hyperplastic eosinophilic sinusitis

PURPOSE OF REVIEW

Chronic rhinosinusitis (CRS) is one of the most common chronic illnesses in the United States. Although CRS has been viewed traditionally as an infectious disease, treatment focused on antibiotics and surgery has not infrequently provided disappointing results.

RECENT FINDINGS

Recently much of CRS has been shown to be an eosinophilic inflammatory disease and new anti-inflammatory treatments are being studied.

SUMMARY

This review discusses medical management for chronic hyperplastic eosinophilic sinusitis, including antifungal treatment, low-dose macrolide treatment, antilipid mediator therapy, and new immune-modifying treatments.

Treatment of patients with respiratory reactions to aspirin and nonsteroidal anti-inflammatory drugs

Aspirin exacerbated respiratory disease (AERD) is an adult onset condition manifested 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.

Leukotriene receptors in rhinitis and sinusitis

Cysteinyl leukotrienes (CysLTs) mediate their biologic activities through interactions with the CysLT1 and CysLT2 receptors. CysLT1 receptors are prominently expressed on smooth muscle cells and lung fibroblasts, whereas CysLT2 receptors are expressed on heart Purkinje fiber cells, adrenal chromaffin cells, and endothelial cells. Both receptors are expressed on eosinophils and mast cells, but CysLT1 receptors alone are on neutrophils. Antigen-presenting cells more prominently express the type 2 receptor. CysLT1 receptors are uniquely important for bronchospasm, whereas CysLT2 receptors can stimulate endothelial cell adherence, myofibroblast proliferation, and chemokine production by mast cells. Comprehensive inhibition of the proinflammatory activities of CysLTs might require either combination CysLT1 and CysLT2 receptor antagonists or inhibitors of the CysLT synthesis pathway.

Allergic fungal sinusitis: pathogenesis and management strategies

Allergic fungal sinusitis (AFS) is a noninvasive form of highly recurrent chronic allergic hypertrophic rhinosinusitis that can be distinguished clinically, histopathologically and prognostically from the other forms of chronic fungal rhinosinusitis. There are three invasive (acute necrotising, chronic invasive and granulomatous invasive) and two noninvasive (fungal ball and allergic fungal) forms of fungal rhinosinusitis currently recognised. Confusion in differentiating between the various forms of fungal rhinosinusitis and between other forms of chronic hypertrophic sinus disease (HSD) can be eliminated by adhering to strict diagnostic criteria. Although there are characteristic presenting clinical history and physical examination findings, laboratory test results, including elevated total serum IgE and positive inhalant allergy skin tests, and sinus computed tomography scans showing chronic rhinosinusitis (often with the presence of hyperattenuating sinus contents) diagnosis of AFS is essentially based on histopathology obtained from sinus surgery. Histopathology shows the presence of eosinophilic-lymphocytic sinus mucosal inflammation, extramucosal allergic mucin (that is also seen grossly at surgery as a characteristic 'peanut-buttery' material), and scattered silver stain positive fungal hyphae within the allergic mucin but not in the mucosa. Treatment and follow up of AFS has been based on its immunopathological analogy to allergic bronchopulmonary aspergillosis, a similar noninvasive fungal hypersensitivity disorder of the lung, and its clinical and pathophysiological relationship to other forms of HSD and asthma. Treatment involves aggressive sinus surgery followed by medical management that includes allergen immunotherapy, topical and systemic corticosteroids, antihistamines and antileukotrienes. Total serum IgE levels should be followed postoperatively as they can be prognostic for recurrent disease. Close follow up and coordination of treatment by both medical and surgical physicians as a team leads to the best clinical outcomes. Ongoing studies are being directed at furthering our understanding of the pathophysiological relationships and treatment options for AFS, and other common forms of chronic hypertrophic rhinosinusitis disorders.

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.

Aspirin intolerance and the cyclooxygenase-leukotriene pathways

PURPOSE OF REVIEW

In up to 10% of patients with bronchial asthma, aspirin and other nonsteroidal antiinflammatory drugs precipitate asthmatic attacks. This is a hallmark of a distinct clinical syndrome that develops according to a characteristic sequence of symptoms. Here we discuss its clinical picture and management as related to the abnormalities in arachidonic acid transformations.

RECENT FINDINGS

At the biochemical level, the characteristic feature is profound alteration in eicosanoid biosynthesis and metabolism. Major advances in the molecular biology of eicosanoids, exemplified by the cloning of cysteinyl-leukotriene receptors and discovery of a whole family of cyclooxygenase enzymes, offer new insights into mechanisms operating in aspirin-induced asthma. Clinical interest has been enhanced by the introduction into therapy of highly specific cyclooxygenase-2 inhibitors and antileukotriene drugs.

SUMMARY

Recent studies have improved our understanding of mechanisms operating in asthma and unvieled the role of eicosanoid mediators in pulmonary disease.

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.

Targeting cysteinyl leukotrienes in patients with rhinitis, sinusitis and paranasal polyps

Leukotrienes have been known in the field of immunology since the 1930s. At that time they were referred to as the slow reacting substance of anaphylaxis. They were not, however, characterized until the 1980s, when they were noted to be formed during the breakdown of arachidonic acid by the enzyme 5-lipoxygenase. The leukotrienes consist of leukotriene (LT) A4, LTB4, LTC4, LTD4 and LTE4, so named because the molecule was originally isolated from leukocytes and therefore its carbon backbone contains three double bonds in series, which constitutes a trion. This structural information provided the key to the oxidative pathway of lipometabolism, known as the 5-lipoxygenase. Leukotrienes are classified as inflammatory mediators, and therefore they are produced by a number of cell types, particularly mast cells, eosinophils, basophils, macrophages and monocytes. With the identification of asthma, allergic rhinitis and paranasal sinusitis associated with inflammatory pathways, the leukotrienes have been implicated in the pathogenesis of these conditions and have become targets for therapeutic modulation. Leukotriene synthesis inhibitors have been used successfully in the treatment of patients with asthma where they have demonstrated the ability to induce bronchial dilatation, provide protection against broncho-provocation tests and significantly diminish symptoms. When it was serendipitously noted that patients who had concomitant nasal pathology also showed improvement, leukotriene synthesis inhibitors were used as adjuvant therapy in the management of patients with rhinitis, sinusitis and nasal polyposis. Preliminary studies have demonstrated improvements in nasal airflow and reduced recurrence of nasal polyps as noted by endoscopy and imaging studies. Leukotriene synthesis inhibitors therefore appear to be a novel treatment modality for patients with rhinitis, sinusitis and nasal polyps when used as adjunctive therapy.

Recent advances in the management of asthma using leukotriene modifiers

Asthma is a chronic inflammatory disease of the airways that affects approximately 100 million people worldwide. In order to reduce symptoms, improve pulmonary function, and decrease morbidity, current treatment guidelines emphasize the importance of controlling the underlying inflammation in patients with asthma. Leukotrienes are leukocyte-generated lipid mediators that promote airway inflammation. Recognition of the importance of leukotrienes in the pathogenesis of asthma has led to the development of leukotriene modifiers, the first new class of drugs for the treatment of asthma to become available in 25 years. Controlled clinical trials with the four currently used leukotriene modifiers (montelukast, zafirlukast, and zileuton in the US and pranlukast in Japan) have established their efficacy in improving pulmonary function, reducing symptoms, decreasing night-time awakenings, and decreasing the need for rescue medications. They exert anti-inflammatory effects that attenuate cellular infiltration and bronchial hyperresponsiveness and complement the anti-inflammatory properties of inhaled corticosteroids. In patients with moderate and severe asthma, they permit tapering of the corticosteroid dose. In patients with exercise-induced asthma, leukotriene modifiers limit the decline in and quicken the recovery of pulmonary functions without the tolerance issues seen with chronic long-acting beta(2)-adrenoceptor agonist use. In patients with aspirin (acetylsalicylic acid)-induced asthma, they improve pulmonary function and shift the dose response curve to the right, reducing the patient's response to aspirin. In patients with seasonal allergic rhinitis, with or without concomitant asthma, they improve nasal, eye, and throat symptoms as well as quality of life. Leukotriene modifiers are generally safe and well tolerated with adverse effect profiles similar to that of placebo. The one safety issue raised with leukotriene modifiers, Churg-Strauss Syndrome, appears to be the unmasking of an already present syndrome that is manifested when the leukotriene modifiers permit corticosteroid doses to be reduced. Although current treatment guidelines recommend their use in patients with mild persistent asthma, these guidelines were developed just as leukotriene modifiers were coming to the market, before much of the clinical efficacy data were published. Because asthma is a heterogeneous disease, the different asthma phenotypes respond differently to therapies; consequently asthma therapy needs to be individualized. Leukotriene modifiers increase the therapeutic options for patients with asthma and, based on recent data, it is expected that future guidelines will describe expanded uses for these agents in clinical circumstances where these drugs are effective.

Allergic rhinitis: systemic inflammation and implications for management

Allergic rhinitis triggers a systemic increase of inflammation. Within minutes of allergen exposure, immune cells release histamine, proteases, cysteinyl leukotrienes, prostaglandins, and cytokines. Some produce the early symptoms, while others augment the production, systemic circulation, and subsequent infiltration of the nasal mucosa with inflammatory cells that sustain the symptoms. Systemic circulation of inflammatory cells permits their infiltration into other tissues where chemoattractant and adhesion molecules already exist. Consequently, allergic rhinitis is linked to comorbid conditions: asthma, chronic hyperplastic eosinophilic sinusitis, nasal polyposis, and serous otitis media. Effective therapy should be directed at underlying inflammation and its systemic manifestations. It should improve the rhinitis and the comorbid conditions. Antihistamines relieve early symptoms by blocking basophil- and mast cell-generated histamine, but they do not significantly influence the pro-inflammatory loop. They are often little better than placebo. Oral corticosteroids provide the systemic anti-inflammatory efficacy, but their toxicity precludes such an approach. Intranasal corticosteroids effectively target the local inflammatory processes of rhinitis, reducing local inflammatory cells within the nares, but they do not directly access tissues involved in the comorbid conditions. Leukotriene modifiers have both systemic anti-inflammatory effects and an acceptable safety profile.

High levels of urinary leukotriene E4 excretion in steroid treated patients with severe asthma

Urinary LTE4 reflects the whole body production of the cysteinyl-leukotrienes (LTC4, LTD4 and LTE4) that are established mediators in asthma. The influence of chronic inhaled and oral glucocorticoid treatment on urinary excretion of leukotriene (LT) E4 was investigated in subjects with asthma. Enzyme immunoassay analysis of LTE4 was performed in spot urine samples collected from 40 patients with severe asthma, 25 patients with mild-moderate asthma and 20 non-asthmatic control subjects. Urinary LTE4 was significantly higher in patients with severe asthma (69.7 +/- 5.5) as compared to mild-moderate asthma (45.7 +/- 3.3 with P < 0.0004) and control (42.5 +/- 2.5 with P < 0.0001). Despite chronic systemic treatment with glucocorticoids, chronically severe asthma had presented with higher levels of LTE4 compared to mild moderate asthma and healthy controls. The findings support previous indications that one important component in asthmatic airway inflammation, the cysteinyl-leukotriene pathway remains relatively unopposed by oral glucocorticoids.

The role of leukotrienes in asthma

Leukotrienes (LT), both the cysteinyl LTs, LTC(4), LTD(4) and LTE(4), as well as LTB(4) have been implicated in the clinical course, physiologic changes, and pathogenesis of asthma. The cysteinyl LTs are potent bronchoconstrictors, which have additional effects on blood vessels, mucociliary clearance and eosinophilic inflammation. In addition, the cysteinyl LTs are formed from cells commonly associated with asthma, including eosinophils and mast cells. LTB(4), whose role is less well defined in asthma, is a potent chemoattractant (and cell activator) for both neutrophils and eosinophils. In the last 5 years, drugs have been developed which block the actions or formation of these mediators. Clinical and physiologic studies have demonstrated that they are modest short-acting bronchodilators, with sustained improvement in FEV(1) occurring in double-blind, placebo-controlled clinical trials for up to 6 months. These drugs have demonstrated efficacy in preventing bronchoconstriction caused by LTs, allergen, exercise and other agents. Additionally, there are multiple published studies which have demonstrated improvement in asthma symptoms, beta agonist use and, importantly, exacerbations of asthma in both adults and children. Comparison studies with inhaled corticosteroids (ICS) suggest that ICS are superior to leukotriene modifying drugs in moderate persistent asthma. However, several published studies now suggest that leukotriene modifying drugs are effective when added to ongoing therapy with ICS, either to improve current symptoms or to decrease the dose of ICS required to maintain control. While an anti-inflammatory effect is suggested, longer-term, earlier intervention, studies are needed to determine whether these compounds will have any effect on the natural history of the disease.

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.

The role of leukotriene inhibitors in patients with paranasal sinus disease

Leukotrienes are inflammatory mediators that are known as the slow-reacting substance of anaphylaxis produced by a number of cell types including mast cells, eosinophils, basophils, macrophages, and monocytes. Synthesis of these mediators results from the cleavage of arachidonic acid in cell membranes, and they exert their biologic effects by binding and activating specific adaptors. This occurs in a series of events that lead to contraction of the human airway smooth muscle, chemotaxis, and increased vascular permeability. These effects have led to their important role in the diseases of asthma, allergic rhinitis, and possible paranasal sinusitis with the formation of nasal polyps. Because these agents lead to the production of symptoms in patients that are asthmatic, the use of leukotriene enzyme inhibitors, particularly montelukast, and zafirlukasts seem appropriate. These classes of drugs can block the binding of leukotrienes to CysLT(1) receptors. Zileuton is a 5-lipoxygenase inhibitor that prevents the formation of leukotrienes and can also result in the prevention of leukotriene activity. Demonstrated efficacy in these patients in a number of studies has also suggested their role in inhibiting nasal symptoms in asthmatic patients. In addition, it has been suggested by serendipitous observations that many of the aspirin-intolerant patients have nasal polyps and that treatment with the leukotriene inhibitors has resulted in improvement and resolution of the polyps. Therefore, these agents may also play a role in patients afflicted with chronic sinusitis with concomitant nasal polyposis. These papers are discussed in detail because this form of therapy may represent a novel way to treat patients with this malady in addition to or in lieu of surgical treatment and steroid therapy.

Aspirin-induced asthma: advances in pathogenesis, diagnosis, and management

In some asthmatic individuals, aspirin and other nonsteroidal anti-inflammatory drugs (NSAIDs) that inhibit cyclooxygen-ase 1 (COX-1) exacerbate the condition. This distinct clinical syndrome, called aspirin-induced asthma (AIA), is characterized by an eosinophilic rhinosinusitis, nasal polyposis, aspirin sensitivity, and asthma. There is no in vitro test for the disorder, and diagnosis can be established only by provocation challenges with aspirin or NSAIDs. Recent major advances in the molecular biology of eicosanoids, exemplified by the cloning of 2 cysteinyl leukotriene receptors and the discovery of a whole family of cyclooxygenase enzymes, offer new insights into mechanisms operating in AIA. The disease runs a protracted course even if COX-1 inhibitors are avoided, and the course is often severe, many patients requiring systemic corticosteroids to control their sinusitis and asthma. Aspirin and NSAIDs should be avoided, but highly specific COX-2 inhibitors, known as coxibs, are well tolerated and can be safely used. Aspirin desensitization, followed by daily aspirin treatment, is a valuable therapeutic option in most patients with AIA, particularly those with recurrent nasal polyposis or overdependence on systemic corticosteroids.

Natural history and clinical features of aspirin-exacerbated respiratory disease

Aspirin-exacerbated respiratory disease (AERD) is a clinical syndrome characterized by chronic rhinosinusitis, nasal polyposis, asthma and precipitation of asthma, and rhinitis attacks after ingestion of aspirin (ASA) and most other nonsteroidal antiinflammatory drugs (NSAIDs). Although precipitation of asthma attacks by ingestion of ASA and other NSAIDs is considered a hallmark of the syndrome, the respiratory mucosal inflammatory disease process begins and continues in the absence of ongoing or even intermittent exposure to ASA or NSAIDs. The typical patient with AERD is an adult who develops refractory chronic rhinitis in the third or fourth decade of life. The chronic rhinitis evolves into chronic eosinophilic rhinosinusitis with associated nasal polyposis. Anosmia appears in most patients. CT of the sinuses most often demonstrates pansinusitis and patients often undergo multiple sinus operations resulting in only limited temporary benefit. During the evolution of the sinus disease persistent asthma develops. Finally, if patients are exposed to ASA or NSAIDs acute respiratory reactions begin to occur. Despite subsequent avoidance of ASA and other NSAIDs, the respiratory mucosal inflammatory disease persists, often requiring systemic corticosteroids for control of both upper- and lower-respiratory tract symptoms. Adequate control of asthma can often only be accomplished with the simultaneous control of the associated rhinosinusitis. With few exceptions, once AERD develops it remains for the remainder of the patient s life.

Prevention and treatment of reactions to NSAIDs

Avoidance of ASA and other NSAIDs prevents the reactions and careful attention to clinical history along with patient education are important. However, blanket advice to avoid all NSAIDs is no longer reasonable. Except for AERD and chronic urticaria, cross-reactivity with other NSAIDs does not occur. A physician can definitively prove this by giving the patient another NSAID in their office and observing no reaction. Furthermore, for patients with AERD and chronic urticaria, they can be given the new selective COX-2 inhibitors (rofecoxib and celecoxib) without any cross-reactivity. All AERD patients can be desensitized to ASA and treated with ASA indefinitely. However, ASA desensitization in chronic urticaria is not possible. Underlying mild and moderate AERD responds well to topical and systemic corticosteroids and leukotriene modifiers. However, the severe forms of the disease should be desensitized to ASA and treated with this drug on a long term basis. In the future, new drugs that prevent eosinophil activation and chemotaxis or enhance eosinophil apoptosis are likely to be useful. Specific blockers of the second cystLT receptor would also be useful. Ultimately as the genetics of these heterogeneous disorders are unraveled, gene substitution therapy may be the ultimate answer.

Cysteinyl leukotriene expression in chronic hyperplastic sinusitis-nasal polyposis: importance to eosinophilia and asthma

BACKGROUND

Chronic hyperplastic eosinophilic sinusitis (CHS) results from the unregulated proliferation of eosinophils, T(H)2-like lymphocytes, goblet cells, mast cells, and fibroblasts and is present in most patients with asthma. The frequent coexpression of these disorders and their shared pathophysiology suggests that these are similar disorders affecting the upper and lower airways.

OBJECTIVE

We evaluated the expression of cysteinyl leukotrienes (CysLTs) in sinus tissue from subjects with CHS compared with that seen in healthy sinus tissue.

METHODS

Nasal polyp and sinus tissue was evaluated from 58 individuals undergoing elective functional endoscopic sinus surgery. The diagnosis of CHS was demonstrated through the presence of eosinophilia and activated (EG2(+)) eosinophils, as determined by means of tissue immunohistochemistry. Data were compared with those from both nasal polyp tissue without eosinophilic inflammation and healthy control sinus tissue obtained from the sinus ostiomeatal complex at the time of surgery for unrelated disorders. CysLTs were quantified by means of ELISA in lipid-extracted tissue. Activation of the metabolic pathway leading to CysLT synthesis was demonstrated by ribonuclease protection. Subjects were genotyped for leukotriene C(4) (LTC(4)) synthase C-to-A promoter polymorphism.

RESULTS

CysLT concentrations were significantly higher in tissue obtained from subjects with CHS (776.7 +/- 201.9 pg/g tissue) compared with that seen in healthy sinus tissue (355.7 +/- 101.6 pg/g tissue, P <.03). CysLT concentrations within noneosinophilic nasal polyps (328.0 +/- 116.4 pg/g tissue) were similar to those in control tissue. The presence of CysLTs in CHS was associated with increased expression of LTC(4) synthase mRNA. The C-to-A promoter polymorphism was associated with trends toward the increased presence of CHS and CysLTs.

CONCLUSIONS

CHS is characterized by the increased presence of CysLTs when compared with concentrations seen in tissue from patients with chronic inflammatory sinusitis or healthy sinus tissue. These studies support the use of LT modifiers as anti-inflammatory agents that might have clinical benefit in patients with these disorders.

Long-term treatment with aspirin desensitization in asthmatic patients with aspirin-exacerbated respiratory disease

BACKGROUND

Aspirin desensitization treatment is an option to decrease disease activity and reduce the need for systemic corticosteroids in patients with aspirin-exacerbated respiratory disease (AERD).

OBJECTIVE

This study was designed to determine whether the clinical courses of patients with AERD improved as early as 6 months after starting aspirin desensitization and to compare this with follow-up evaluations after at least a year.

METHODS

Between 1995 and 2000, 172 patients with AERD were admitted to our General Clinical Research Center, were desensitized to and treated with aspirin, were discharged to their home communities, and participated in follow-up interviews and written assessments of their clinical courses.

RESULTS

By the first 6 months of aspirin treatment, there were significant reductions in sinus infections and numbers of short courses of prednisone and improvements in sense of smell and general assessment of nasal-sinus and asthma symptoms (P <.0001). These results persisted for 1 to 5 years (P <.0001). Mean prednisone doses decreased from 10.8 mg/d to 8.1 and 3.6 mg/d at 6 months and greater than 1 year, respectively. Of the 172 patients, 24 (14%) discontinued aspirin treatment because of side effects, and 115 (67%) responded to aspirin treatment. After eliminating those who discontinued aspirin treatment because of side effects, the improvement rate was 115 (78%) of 148 patients. Of the 126 patients who completed a year or more of aspirin treatment, 110 (87%) experienced improvement.

CONCLUSION

Aspirin desensitization followed by daily aspirin is efficacious by at least the first 6 months of treatment and continues to be effective for up to 5 years of follow-up.

Neurogenic inflammation of the bladder

Current evidence suggests multiple and redundant pathways through which the nervous system can initiate, amplify, and perpetuate inflammation. Many of the processes initiated by neurogenic inflammation have the capacity to recruit the participation of additional sensory nerves. These observations indicate that effective strategies for prevention or treatment of neurogenic inflammation of the bladder will entail or require intervention at multiple points. It has been observed that pain management in the future will be based on selective intervention tailored to the specific processes modulating pain perception in individual patients. It is exciting to contemplate the same approach to prevention and treatment of neurogenic bladder inflammation.

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.

Asthma control and patient satisfaction among early pediatric users of montelukast

OBJECTIVE

To assess asthma control and patient satisfaction among pediatric users of montelukast in a clinical practice setting.

STUDY DESIGN

A prospective study of 175 children with persistent asthma, 6 to 14 years of age, who initiated treatment with montelukast between Feb-1998 and Aug-1998, in primary care and pediatric offices across the United States. Data on asthma control and satisfaction with treatment was collected in physicians' offices after enrollment and by survey to the patients' homes at 1 month of treatment.

RESULTS

Across the study population, improvements in mean scores for asthma control and parent satisfaction were observed at the 1-month follow-up compared with baseline. At 1 month, 57.7% of patients had none offour issues indicative of poor asthma control, compared with 19.4% at baseline. Similarly, after 1 month of treatment with montelukast, 2.7 times as many parents reported being very satisfied with asthma therapy (using montelukast) compared with the previous controller therapy regimen at baseline. During the 1-month follow-up period, montelukast was used as the only controller medication by 18.3% of patients, and in combination with another controller medication by 81.7%.

CONCLUSIONS

Observations from this study over one month suggest that a significant percentage of pediatric patients successfully managed their asthma with montelukast and their parents were satisfied with their medication, compared to baseline.

Zafirlukast has no beneficial effects in the treatment of chronic urticaria

BACKGROUND

Leukotriene receptor antagonists have shown some efficacy in t he treatment of asthma. Injection of LTC4, LTD4 and LTE4 into the skin leads to a weal-and-flare reaction, suggesting an involvement of leukotrienes in the pathogenesis of urticaria. Indeed, various reports have indicated a beneficial effect for leukotriene receptor antagonists in patients with chronic urticaria.

OBJECTIVE

To determine the therapeutic effect of the leukotriene receptor antagonist zafirlukast in patients with chronic urticaria.

METHODS

The study was a double-blind, placebo-controlled, cross-over study lasting for 12 weeks. Fifty-two patients with chronic urticaria were investigated at a university hospital. The patients were randomized to receive 20 mg zafirlukast b.i.d. or placebo and cross-over was scheduled after 6 weeks. The efficacy of the treatment was evaluated by a daily symptom score, six physical examinations, the requirement of rescue antihistamines (acrivastine) and an overall assessment by the patient andthe investigating physician.

RESULTS

Forty-six patients completed the study: zafirlukast was well tolerated without alteration of the investigated laboratory parameters. In comparison with placebo, treatment with zafirlukast resulted in no significant positive effect for any of the efficacy measures. Moreover, we were unable to identify any subgroup of patients with chronic urticaria responding with a therapeutic benefit.

CONCLUSIONS

The leukotriene receptor antagonist zafirlukast does not provide a significant therapeutic benefit at a dose of 20 mg b.i.d. in patients with chronic urticaria.

Clinical and genetic features underlying the response of patients with bronchial asthma to treatment with a leukotriene receptor antagonist

BACKGROUND

Treatment with antileukotriene drugs results in clinical improvement in many, though not all, patients with asthma. It can be hypothesized that the subpopulation of asthmatic patients, characterized by aspirin intolerance and cysteinyl-leukotriene overproduction, might profit most from antileukotriene treatment.

MATERIALS AND METHODS

We compared the clinical response to montelukast in two well-matched groups of patients with mild asthma: 26 aspirin-intolerant asthmatics (AIAs) and 33 aspirin-tolerant asthmatics (ATAs). We also searched for possible predictors of the clinical response among the parameters reflecting the expression and production of cysteinyl-leukotrienes (cys-LTs). This was an 8-week, single-blind, placebo-controlled trial.

RESULTS

Following a 3-week montelukast 10 mg day-1 treatment compared with placebo, there was a statistically significant reduction in the mean daytime and nocturnal asthma symptoms and beta 2-agonist use, as well as a significant improvement in the morning and evening peak expiratory flows and quality of life. Both groups showed a similar significant improvement in the parameters studied. Clinical response did not correlate with the baseline urinary LTE4 excretion level. Improvement of asthma was observed mostly in patients with a low baseline and non-IL-5 inducible expression of LTC4 synthase (LTC4S) mRNA in eosinophils. There was a trend toward a better response in carriers of LTC4S allele C, but no relationship to the CC10 genetic polymorphism.

CONCLUSIONS

No difference in the clinical response to the montelukast treatment was observed between the AIAs and the ATAs.

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.

Asthma

Asthma is one of the commonest chronic diseases of affluent societies. The striking increase in prevalence of asthma over recent decades and the rarity of this disease in less affluent populations confirms the importance of environmental factors in the cause of asthma--although which environmental factors are responsible is still not clear. Family studies show that genetic factors are also important in determining individual susceptibility to asthma, with results of genetic studies suggesting that there are many genes with moderate effects rather than a few major genes. Asthmatic airways show inflammation and remodelling, with CD4+ helper cells, mast cells, and eosinophils characterising the inflammatory response. Inhaled corticosteroids remain the cornerstone of treatment with the addition of long-acting beta agonists as the next step if symptoms continue. Leukotriene antagonists, the only new drugs to reach the market in the past decade, have modest effects. However, a better understanding of the mechanisms underlying asthma and the genetic and environmental factors that predispose individuals to asthma should lead to better preventative strategies and new therapeutic approaches.

Leukotriene modifiers

Leukotrienes (LTs) are 5-lipoxygenase products formed from arachidonic acid metabolism. There is compelling evidence that LTs play an important role in the pathogenesis of asthma. LTs affect vascular permeability, mucus production, and smooth muscle constriction, and may contribute to airway remodeling. In mild-to-moderate asthma, LT modifiers improve measures of airflow limitation and quality of life and reduce the frequency of asthma exacerbations and the need for short-acting bronchodilator therapy. In moderate-to-severe asthma, an LT modifier in combination with an inhaled corticosteroid results in improvements in lung function and asthma control over that achieved with an inhaled corticosteroid alone. LT modifiers are effective in the treatment of exercise-induced bronchoconstriction and aspirin-induced asthma. There are few adverse effects of LT modifiers.