Effect of 5-lipoxygenase inhibition on bronchoconstriction and airway inflammation in nocturnal asthma

Exploration of Parteck® SRP 80 and Hypromellose for Chronomodulated Release of LTD4 Receptor Antagonist and Statistical Optimization Using Central Composite Design

To manage early morning symptoms of nocturnal bronchial asthma, a chronotherapeutic drug delivery system (ChrDDS) of montelukast sodium was designed and developed utilizing non-saccharide, fully synthetic Parteck® SRP 80, and hydrophilic cellulose derivative hydroxypropyl methylcellulose (HPMC). Recurrent lag phase, each followed by the release of a fraction of the drug dose, can be achieved by formulating a "tablets in a capsule" system containing more than one compressed coated tablet encapsulated in an enteric-coated capsule. Lag time in this study was controlled by the compressed coating of HPMC K4M and a blend of ethyl cellulose and Carbopol polymer. Assembly of the system includes two compressed coated tablets encapsulated in a capsule which was further proceeded for enteric coating in a conventional, a novel wax-based, and a Eudracap™ enteric-coated capsule. The optimized formulation of directly compressed tablets of Parteck ® SRP 80 showed a hardness of 8.8 kg/cm² which is 1.25-fold higher than wet granulated tablets of HPMC. In vitro release data of matrix tablets of Parteck® SRP 80 demonstrated controlled release of drug for a duration of up to 10.8-11 h with changing ratio of polymer and filler. Eudracap™ capsule showed a minimum acid uptake value of 1.75%. The current approach can open a path for the time-regulated release of montelukast that may be beneficial for individuals with episodes of asthma attacks mostly in the early morning.

Nontryptase Urinary and Hematologic Biomarkers of Mast Cell Expansion and Mast Cell Activation: Status 2022

Quantitation of urinary metabolites of histamine, prostaglandin D₂, and leukotriene E₄ can fill the gap in our current efforts to improve diagnosis and management of symptomatic patients with systemic mastocytosis, and/or mast cell activation syndrome, In addition, patients symptomatic due to mast cell activation but who do not meet all the criteria for mast cell activation syndrome can have elevated baseline mediator metabolites. Serum tryptase levels have been the workhorse in diagnosing these disorders, but it has several drawbacks including the need to obtain acute and baseline samples, which require 2 visits to health care facilities and 2 venipunctures. Recently, increased baseline tryptase level has been reported in hereditary alpha tryptasemia, complicating diagnostic possibilities of an increased baseline tryptase level. Furthermore, no treatment can specifically be targeted at tryptase itself. In contrast, the finding of 1 or more elevated urinary levels of histamine, prostaglandin D₂, and/or leukotriene E₄ metabolites (1) greatly narrows diagnostic possibilities for causes of symptoms; (2) informs the practitioner what specific metabolic pathways are involved; and (3) targets the treatment in a specific, direct fashion. As a bonus, baseline spot/random urine samples can be obtained by the patients themselves and repeated at exactly the correct time when symptoms occur.

Imbalanced serum levels of resolvin E1 (RvE1) and leukotriene B4 (LTB4) in patients with allergic rhinitis

Timely and successful resolution of acute inflammation plays a crucial role in preventing the development of chronic airway inflammation in allergic rhinitis (AR). This study intends to assess the serum levels of pro-inflammatory leukotriene B4 (LTB4), anti-inflammatory mediators, including resolvin E1 (RvE1), RvD1, IL-10, and TGF-β, besides mRNA expression level of G-protein coupled receptor 120 (GPR120) and peroxisome proliferator-activated receptor-γ (PPAR-γ) receptors in peripheral blood leukocytes of AR patients. Thirty-seven AR patients and thirty age- and gender-matched healthy subjects were enrolled in this study. The serum levels of LTB4, RvE1, RvD1, IL-10, and TGF-β were measured using enzyme-linked immunosorbent assay (ELISA) technique, and the mRNA expression level of GPR120 and PPAR-γ was assessed by the real-time PCR method. The serum levels of RvE1 and LTB4 were significantly higher in patients with AR than in healthy subjects (P < 0.01 and P < 0.0001, respectively). However, a significantly lower ratio of RvE1 and RvD1 to LTB4 was found in patients with AR relative to healthy subjects (P < 0.05 and P < 0.0001, respectively). Likewise, the serum levels of both IL-10 and TGF-β cytokines were significantly reduced in patients with AR compared to healthy subjects (P < 0.01 and P < 0.0001, respectively). Furthermore, the mRNA expression of PPAR-γ was significantly lower in patients with AR than in healthy subjects (P < 0.05). Our findings indicate that imbalanced pro-resolving lipid mediator RvE1 and pro-inflammatory LTB4 might contribute to the defective airway inflammation-resolution and subsequent progression toward chronic inflammation in AR patients.

Leukotriene A4 Hydrolase Activation and Leukotriene B4 Production by Eosinophils in Severe Asthma

Asthma is associated with the overproduction of leukotrienes (LTs), including LTB4. Patients with severe asthma can be highly responsive to 5-lipoxygenase (5-LO) inhibition, which blocks production of both the cysteinyl LTs and LTB4. Production of LTB4 has traditionally been ascribed to neutrophils, mononuclear phagocytes, and epithelial cells, and acts as a chemoattractant for inflammatory cells associated with asthma. The source of LTB4 is unclear, especially in eosinophilic asthma. We speculated that the benefit of 5-LO inhibition could be mediated in part by inhibition of eosinophil-derived LTB4. LTB4 concentrations were assayed in BAL fluid from patients with severe asthma characterized by isolated neutrophilic, eosinophilic, and paucigranulocytic inflammation. Expression of LTA4 hydrolase (LTA4H) by airway eosinophils was determined by immunohistochemistry (IHC). Subsequently, peripheral blood eosinophils were activated and secreted LTB4 was quantified by enzyme immunoassay. Blood eosinophil LTA4H expression was determined by flow cytometry, qPCR, and IHC. LTB4 concentrations were elevated in BAL fluid from patients with severe asthma, including those with isolated eosinophilic inflammation, and these eosinophils displayed LTA4H via IHC. LTA4H expression by blood eosinophils was confirmed by flow cytometry, IHC, and qPCR. Robust LTB4 production by blood eosinophils was observed in response to some, but not all, stimuli. We demonstrated that eosinophils express LTA4H transcripts and protein, and can be stimulated to secrete LTB4. We speculate that in many patients with asthma, eosinophil-derived LTB4 is increased, and this may contribute to the efficacy of 5-LO inhibition.

Unique Lipid Signatures of Extracellular Vesicles from the Airways of Asthmatics

Asthma is a chronic inflammatory disease process involving the conductive airways of the human lung. The dysregulated inflammatory response in this disease process may involve multiple cell-cell interactions mediated by signaling molecules, including lipid mediators. Extracellular vesicles (EVs) are lipid membrane particles that are now recognized as critical mediators of cell-cell communication. Here, we compared the lipid composition and presence of specific lipid mediators in airway EVs purified from the bronchoalveolar lavage (BAL) fluid of healthy controls and asthmatic subjects with and without second-hand smoke (SHS) exposure. Airway exosome concentrations were increased in asthmatics, and correlated with blood eosinophilia and serum IgE levels. Frequencies of HLA-DR⁺ and CD54⁺ exosomes were also significantly higher in asthmatics. Lipidomics analysis revealed that phosphatidylglycerol, ceramide-phosphates, and ceramides were significantly reduced in exosomes from asthmatics compared to the non-exposed control groups. Sphingomyelin 34:1 was more abundant in exosomes of SHS-exposed asthmatics compared to healthy controls. Our results suggest that chronic airway inflammation may be driven by alterations in the composition of lipid mediators within airway EVs of human subjects with asthma.

Role of neutrophils in allergic asthma

The contribution of neutrophils to asthma pathogenesis has been mainly studied in the context of non-allergic neutrophilic asthma. However, neutrophils can also be rapidly recruited and are largely present in the airways of allergic eosinophilic asthmatic patients. Under these circumstances, they possess specific phenotypic features distinguishing them from resting blood neutrophils and are endowed with particular functions. The exact contribution of neutrophils to allergic asthma pathogenesis is still unclear, but growing experimental evidence supports the ability of neutrophils or neutrophil-derived products to influence the underlying allergic type 2 immune response and cardinal features of allergic asthma, thus shedding new light on neutrophil biology and functions in an allergic context.

Importance of the leukotriene B4-BLT1 and LTB4-BLT2 pathways in asthma

For several decades, the leukotriene pathways have been implicated as playing a central role in the pathophysiology of asthma. The presence and elevation of numerous metabolites in the blood, sputum, and bronchoalveolar lavage fluid from asthmatics or experimental animals adds support to this notion. However, targeting of the leukotriene pathways has had, in general, limited success. The single exception in asthma therapy has been targeting of the cysteinyl leukotriene receptor 1, which clinically has proven effective but only in certain clinical situations. Interference with 5-lipoxygenase has had limited success, in part due to adverse drug effects. The importance of the LTB4-BLT1 pathway in asthma pathogenesis has extensive experimental support and findings, albeit limited, from clinical samples. The LTB4-BLT1 pathway was shown to be important as a neutrophil chemoattractant. Despite observations made more than two decades ago, the LTB4-BLT1 pathway has only recently been shown to exhibit important activities on subsets of T lymphocytes, both as a chemoattractant and on lymphocyte activation, as well as on dendritic cells, the major antigen presenting cell in the lung. The role of BLT2 in asthma remains unclear. Targeting of components of the LTB4-BLT1 pathway offers innovative therapeutic opportunities especially in patients with asthma that remain uncontrolled despite intensive corticosteroid treatment.

The peroxisome proliferator-activated receptor agonist pioglitazone and 5-lipoxygenase inhibitor zileuton have no effect on lung inflammation in healthy volunteers by positron emission tomography in a single-blind placebo-controlled cohort study

Background

Anti-inflammatory drug development efforts for lung disease have been hampered in part by the lack of noninvasive inflammation biomarkers and the limited ability of animal models to predict efficacy in humans. We used ¹⁸F-fluorodeoxyglucose (¹⁸F-FDG) positron emission tomography (PET) in a human model of lung inflammation to assess whether pioglitazone, a peroxisome proliferator-activated receptor-γ (PPAR-γ) agonist, and zileuton, a 5-lipoxygenase inhibitor, reduce lung inflammation.

Methods

For this single center, single-blind, placebo-controlled cohort study, we enrolled healthy volunteers sequentially into the following treatment cohorts (N = 6 per cohort): pioglitazone plus placebo, zileuton plus placebo, or dual placebo prior to bronchoscopic endotoxin instillation. ¹⁸F-FDG uptake pre- and post-endotoxin was quantified as the Patlak graphical analysis-determined K_i (primary outcome measure). Secondary outcome measures included the mean standard uptake value (SUV_mean), post-endotoxin bronchoalveolar lavage (BAL) cell counts and differentials and blood adiponectin and urinary leukotriene E₄ (LTE₄) levels, determined by enzyme-linked immunosorbent assay, to verify treatment compliance. One- or two-way analysis of variance assessed for differences among cohorts in the outcome measures (expressed as mean ± standard deviation).

Results

Ten females and eight males (29±6 years of age) completed all study procedures except for one volunteer who did not complete the post-endotoxin BAL. K_i and SUV_mean increased in all cohorts after endotoxin instillation (K_i increased by 0.0021±0.0019, 0.0023±0.0017, and 0.0024±0.0020 and SUV_mean by 0.47±0.14, 0.55±0.15, and 0.54±0.38 in placebo, pioglitazone, and zileuton cohorts, respectively, p<0.001) with no differences among treatment cohorts (p = 0.933). Adiponectin levels increased as expected with pioglitazone treatment but not urinary LTE₄ levels as expected with zileuton treatment. BAL cell counts (p = 0.442) and neutrophil percentage (p = 0.773) were similar among the treatment cohorts.

Conclusions

Endotoxin-induced lung inflammation in humans is not responsive to pioglitazone or zileuton, highlighting the challenge in translating anti-inflammatory drug efficacy results from murine models to humans.

Trial registration

ClinicalTrials.gov NCT01174056.

Asthma and the Risk of Rheumatoid Arthritis: An Insight into the Heterogeneity and Phenotypes of Asthma

Asthma is traditionally regarded as a chronic airway disease, and recent literature proves its heterogeneity, based on distinctive clusters or phenotypes of asthma. In defining such asthma clusters, the nature of comorbidity among patients with asthma is poorly understood, by assuming no causal relationship between asthma and other comorbid conditions, including both communicable and noncommunicable diseases. However, emerging evidence suggests that the status of asthma significantly affects the increased susceptibility of the patient to both communicable and noncommunicable diseases. Specifically, the impact of asthma on susceptibility to noncommunicable diseases such as chronic systemic inflammatory diseases (e.g., rheumatoid arthritis), may provide an important insight into asthma as a disease with systemic inflammatory features, a conceptual understanding between asthma and asthma-related comorbidity, and the potential implications on the therapeutic and preventive interventions for patients with asthma. This review discusses the currently under-recognized clinical and immunological phenotypes of asthma; specifically, a higher risk of developing a systemic inflammatory disease such as rheumatoid arthritis and their implications, on the conceptual understanding and management of asthma. Our discussion is divided into three parts: literature summary on the relationship between asthma and the risk of rheumatoid arthritis; potential mechanisms underlying the association; and implications on asthma management and research.

Neutrophil recruitment by allergens contribute to allergic sensitization and allergic inflammation

PURPOSE OF REVIEW

To discuss the presence and role of neutrophils in asthma and allergic diseases, and outline the importance of pollen and cat dander-induced innate neutrophil recruitment in induction of allergic sensitization and allergic inflammation.

RECENT FINDINGS

Uncontrolled asthma is associated with elevated numbers of neutrophils, and levels of neutrophil-attracting chemokine IL-8 and IL-17 in bronchoalveolar lavage fluids. These parameters negatively correlate with lung function. Pollen allergens and cat dander recruit neutrophils to the airways in a toll-like receptor 4, myeloid differentiation protein-2, and chemokine (C-X-C motif) receptor (CXCR) 2-dependent manner. Repeated recruitment of activated neutrophils by these allergens facilitates allergic sensitization and airway inflammation. Inhibition of neutrophil recruitment with CXCR2 inhibitor, disruption of toll-like receptor 4, or small interfering RNA against myeloid differentiation protein-2 also inhibits allergic inflammation. The molecular mechanisms by which innately recruited neutrophils contribute to shifting the airway inflammatory response induced by allergens from neutrophilic to an eosinophilic-allergic is an area of active research.

SUMMARY

Recent studies have revealed that neutrophil recruitment is important in the development of allergic sensitization and inflammation. Inhibition of neutrophils recruitment may be a strategy to control allergic inflammation.

Glucocorticoid-Induced Attenuation of the Inflammatory Response in Zebrafish

Glucocorticoids are steroid hormones that are secreted upon stress. Their effects are mediated by the glucocorticoid receptor, which acts as a transcription factor. Because the antiinflammatory activity of glucocorticoids has been well established, they are widely used clinically to treat many inflammatory and immune-related diseases. However, the exact specificity, mechanisms, and level of regulation of different inflammatory pathways have not been fully elucidated. In the present study, a tail fin amputation assay was used in 3-day-old zebrafish larvae to study the immunomodulatory effects of the synthetic glucocorticoid beclomethasone. First, a transcriptome analysis was performed, which showed that upon amputation mainly immune-related genes are regulated. This regulation was inhibited by beclomethasone for 86% of regulated genes. For two immune-related genes, tlr4bb and alox5ap, the amputation-induced increase was not attenuated by beclomethasone. Alox5ap is involved in eicosanoid biosynthesis, but the increase in leukotriene B4 concentration upon amputation was abolished, and lipoxin A4 levels were unaffected by beclomethasone. Furthermore, we studied the migration of neutrophils and macrophages toward the wound site. Our results show that amputation induced migration of both types of leukocytes and that this migration was dependent on de novo protein synthesis. Beclomethasone treatment attenuated the migratory behavior of neutrophils in a glucocorticoid receptor-dependent manner but left the migration of macrophages unaffected. In conclusion, beclomethasone has a dramatic inhibitory effect on the amputation-induced proinflammatory gene regulation, and this is reflected in an inhibition of the neutrophil migration but not the migration of macrophages, which are likely to be involved in inflammation resolution.

The role of leukotrienes in allergic diseases

Leukotrienes (LTs), both LTB4 and the cysteinyl LTs (CysLTs) LTC4, LTD4 and LTE4, are implicated in a wide variety of inflammatory disorders. These lipid mediators are generated from arachidonic acid via multistep enzymatic reactions through which arachidonic acid is liberated from membrane phospholipids through the action of phospholipase A2. LTB4 and CysLTs exert their biological effects by binding to cognate receptors, which belong to the G protein-coupled receptor superfamily. LTB4 is widely considered to be a potent chemoattractant for most subsets of leukocytes, whereas CysLTs are potent bronchoconstrictors that have effects on airway remodeling. LTs play a central role in the pathogenesis of asthma and many other inflammatory diseases. This review will provide an update on the synthesis, biological function, and relevance of LTs to the pathobiology of allergic diseases, and examine the current and future therapeutic prospects of LT modifiers.

Urinary LTE4 levels as a diagnostic marker for IgE-mediated asthma in preschool children: a birth cohort study

Objectives

Leukotrienes play a central pathophysiological role in allergic asthma. The aim of this study was to investigate the utility of measuring urinary leukotriene E₄ (LTE₄) levels in the diagnosis of atopic diseases in early childhood.

Methods

Children aged 0 through 4 years from a birth cohort in the Prediction of Allergies in Taiwanese Children (PATCH) study were enrolled. Urinary LTE₄ levels were measured and its association between total serum IgE levels, allergen-specific IgE sensitization and atopic diseases were assessed.

Results

A total of 182 children were regular followed up at clinics for a four-year follow-up period. Urinary LTE₄ levels appeared to be elevated in children with total serum IgE levels exceeding 100 kU/L, allergen-specific IgE sensitization after 2 years of age. Elevation of urinary LTE₄ levels (≥500 pg/mg of creatinine) significantly discriminated high serum total IgE levels (≥100 kU/L) at age 2 (P = 0.027). A higher level of total serum IgE or urinary LTE₄ was significantly associated with the risk of developing allergic rhinitis and asthma at age 3. A significantly higher urinary LTE₄ level was found in children with a combination of IgE sensitization and asthma at age 4.

Conclusions

Urinary LTE₄ levels appear to be highly associated with IgE sensitization and its related allergic airway diseases after age 2. The measurement of urinary LTE₄ (≥500 pg/mg of creatinine) could not only be a non-invasive method for atopic predisposition but also potentially provide a strategy for the diagnosis and management of asthma in preschool children.

A turn on and a turn off: BLT1 and BLT2 mechanisms in the lung

Leukotriene B4 (LTB4), a potent lipid mediator of inflammation derived from arachidonic acid through the action of 5-lipoxygenase, has been implicated in the pathophysiology of several inflammatory diseases, including asthma and chronic obstructive pulmonary disease. A high-affinity LTB4 receptor BLT1 has been shown to exert proinflammatory roles. A cyclooxygenase metabolite, 12(S)-hydroxyheptadeca-5Z, 8E, 10E-trienoic acid (12-HHT), is an endogenous ligand for BLT2, a low-affinity LTB4 receptor. The recent study indicated that BLT2 has a protective role in allergic airway inflammation, suggesting different functions between BLT1 and BLT2 in the pathogenesis of asthma. Selective BLT1 antagonists may have a potential therapeutic application in patients with asthma, and BLT2 may represent a novel therapeutic target for lung diseases.

Which biomarkers are effective for identifying Th2-driven inflammation in asthma?

Recognition of asthma as a heterogeneous disease revealed different potential molecular targets and urged the development of targeted, customized treatment modalities. Evidence was provided for different inflammatory subsets of asthma and more recently, further refined to T helper (Th)2-high and Th2-low subphenotypes with different responsiveness to standard and targeted pharmacotherapy. Given these differences in immunology and pathophysiology, proof of concept studies of novel treatment modalities for asthma should be performed in adequate, well-defined phenotypes. In this review, we describe both existing and novel biomarkers of Th2-inflammation in asthma that can be applied to classify asthma subphenotypes in clinical studies and for treatment monitoring.

Predictors of asthma control and lung function responsiveness to step 3 therapy in children with uncontrolled asthma

BACKGROUND

Predictors of improvement in asthma control and lung function to step 3 therapy in children with persistent asthma have not been identified despite reported heterogeneity in responsiveness.

OBJECTIVE

We sought to evaluate potential predictors of asthma control and lung function responsiveness to step 3 therapy.

METHODS

A post hoc analysis from the Best Add-On Giving Effective Response (BADGER) study tested the association between baseline biological, asthma control, pulmonary function, and demographic markers and responsiveness to step-up to a higher dose of inhaled corticosteroid (ICS step-up therapy) or addition of leukotriene receptor antagonist (LTRA step-up therapy) or long-acting β₂-agonist (LABA step-up therapy).

RESULTS

In multivariate analyses higher impulse oscillometry reactance area was associated (P = .048) with a differential FEV₁ response favoring LABA over ICS step-up therapy, whereas higher urinary leukotriene E₄ levels were marginally (P = .053) related to a differential FEV₁ response favoring LTRA over LABA step-up therapy. Predictors of differential responses comparing ICS with LTRA step-up therapy were not apparent, probably because of suppression of allergic markers with low-dose ICS treatment. Minimal overlap was seen across FEV₁ and asthma control day predictors, suggesting distinct mechanisms related to lung function and asthma control day responses.

CONCLUSION

Levels of impulse oscillometry reactance area indicating peripheral airway obstruction and urinary leukotriene E₄ levels indicating cysteinyl leukotriene inflammation can differentiate LABA step-up responses from responses to LTRA or ICS step-up therapy. Further studies with physiologic, genetic, and biological markers related to these phenotypes will be needed to predict individual responses to LABA step-up therapy.

Leukotriene B4-driven neutrophil recruitment to the skin is essential for allergic skin inflammation

Scratching triggers skin flares in atopic dermatitis. We demonstrate that scratching of human skin and tape stripping of mouse skin cause neutrophil influx. In mice, this influx was largely dependent on the generation of leukotriene B4 (LTB4) by neutrophils and their expression of the LTB4 receptor BLT1. Allergic skin inflammation in response to epicutaneous (EC) application of ovalbumin to tape-stripped skin was severely impaired in Ltb4r1(-/-) mice and required expression of BLT1 on both T cells and non-T cells. Cotransfer of wild-type (WT) neutrophils, but not neutrophils deficient in BLT1 or the LTB4-synthesizing enzyme LTA4H, restored the ability of WT CD4(+) effector T cells to transfer allergic skin inflammation to Ltb4r1(-/-) recipients. Pharmacologic blockade of LTB4 synthesis inhibited allergic skin inflammation elicited by cutaneous antigen challenge in previously EC-sensitized mice. Our results demonstrate that a neutrophil-T cell axis reliant on LTB4-BLT1 interaction is required for allergic skin inflammation.

Chronotherapeutics--a chronopharmaceutical approach to drug delivery in the treatment of asthma

Bronchial asthma is a chronic inflammatory disorder of the airways associated with airflow obstruction that is reversible spontaneously or with treatment. Bronchial asthma is a disease based on established circadian rhythm. The symptoms of asthma worsen during midnight to early morning and therefore it is required to deliver the drug in such fashion that effective treatment can be obtained during the time of asthma attacks. Chronotherapy is an approach that fulfills the criteria of drug delivery at a specific time as per the pathophysiological need of the disease, to improve patient compliance. The current article focuses on the chronotherapy of bronchial asthma, methodologies involved for the existing systems, recent updates and different chronopharmaceutical technologies currently available in the market. Chronotherapy with different categories of bronchial asthma medications also has been reviewed.

Biomarkers in asthma: a real hope to better manage asthma

Diagnosis and treatment of asthma are currently based on assessment of patient symptoms and physiologic tests of airway reactivity. Research over the past decade has identified an array of biochemical and cellular biomarkers, which reflect the heterogeneous and multiple mechanistic pathways that may lead to asthma. These mechanistic biomarkers offer hope for optimal design of therapies targeting the specific pathways that lead to inflammation. This article provides an overview of blood, urine, and airway biomarkers; summarizes the pathologic pathways that they signify; and begins to describe the utility of biomarkers in the future care of patients with asthma.

Tissue-based and bronchoalveolar lavage-based biomarkers in asthma

In this article, tissue and bronchoalveolar lavage biomarkers of asthma are evaluated for their use in asthma and evaluated in the context of the phenotype that they may best represent. It is hoped that studies that better link biomarkers to specific phenotypes will eventually improve the ability to evaluate genetic features, diagnose, measure progression, and tailor treatments. Although some biomarkers may only be associated with disease, it is also likely that some may be mechanistically involved. Some of these biomarkers may then also become targets for specific treatment.

Anti-leukotriene agents compared to inhaled corticosteroids in the management of recurrent and/or chronic asthma in adults and children

BACKGROUND

Anti-leukotrienes (5-lipoxygenase inhibitors and leukotriene receptors antagonists) serve as alternative monotherapy to inhaled corticosteroids (ICS) in the management of recurrent and/or chronic asthma in adults and children.

OBJECTIVES

To determine the safety and efficacy of anti-leukotrienes compared to inhaled corticosteroids as monotherapy in adults and children with asthma and to provide better insight into the influence of patient and treatment characteristics on the magnitude of effects.

SEARCH METHODS

We searched MEDLINE (1966 to Dec 2010), EMBASE (1980 to Dec 2010), CINAHL (1982 to Dec 2010), the Cochrane Airways Group trials register, and the Cochrane Central Register of Controlled Trials (Dec 2010), abstract books, and reference lists of review articles and trials. We contacted colleagues and the international headquarters of anti-leukotrienes producers.

SELECTION CRITERIA

We included randomised trials that compared anti-leukotrienes with inhaled corticosteroids as monotherapy for a minimum period of four weeks in patients with asthma aged two years and older.

DATA COLLECTION AND ANALYSIS

Two review authors independently assessed the methodological quality of trials and extracted data. The primary outcome was the number of patients with at least one exacerbation requiring systemic corticosteroids. Secondary outcomes included patients with at least one exacerbation requiring hospital admission, lung function tests, indices of chronic asthma control, adverse effects, withdrawal rates and biological inflammatory markers.

MAIN RESULTS

Sixty-five trials met the inclusion criteria for this review. Fifty-six trials (19 paediatric trials) contributed data (representing total of 10,005 adults and 3,333 children); 21 trials were of high methodological quality; 44 were published in full-text. All trials pertained to patients with mild or moderate persistent asthma. Trial durations varied from four to 52 weeks. The median dose of inhaled corticosteroids was quite homogeneous at 200 µg/day of microfine hydrofluoroalkane-propelled beclomethasone or equivalent (HFA-BDP eq). Patients treated with anti-leukotrienes were more likely to suffer an exacerbation requiring systemic corticosteroids (N = 6077 participants; risk ratio (RR) 1.51, 95% confidence interval (CI) 1.17, 1.96). For every 28 (95% CI 15 to 82) patients treated with anti-leukotrienes instead of inhaled corticosteroids, there was one additional patient with an exacerbation requiring rescue systemic corticosteroids. The magnitude of effect was significantly greater in patients with moderate compared with those with mild airway obstruction (RR 2.03, 95% CI 1.41, 2.91 versus RR 1.25, 95% CI 0.97, 1.61), but was not significantly influenced by age group (children representing 23% of the weight versus adults), anti-leukotriene used, duration of intervention, methodological quality, and funding source. Significant group differences favouring inhaled corticosteroids were noted in most secondary outcomes including patients with at least one exacerbation requiring hospital admission (N = 2715 participants; RR 3.33; 95% CI 1.02 to 10.94), the change from baseline FEV(1) (N = 7128 participants; mean group difference (MD) 110 mL, 95% CI 140 to 80) as well as other lung function parameters, asthma symptoms, nocturnal awakenings, rescue medication use, symptom-free days, the quality of life, parents' and physicians' satisfaction. Anti-leukotriene therapy was associated with increased risk of withdrawals due to poor asthma control (N = 7669 participants; RR 2.56; 95% CI 2.01 to 3.27). For every thirty one (95% CI 22 to 47) patients treated with anti-leukotrienes instead of inhaled corticosteroids, there was one additional withdrawal due to poor control. Risk of side effects was not significantly different between both groups.

AUTHORS' CONCLUSIONS

As monotherapy, inhaled corticosteroids display superior efficacy to anti-leukotrienes in adults and children with persistent asthma; the superiority is particularly marked in patients with moderate airway obstruction. On the basis of efficacy, the results support the current guidelines' recommendation that inhaled corticosteroids remain the preferred monotherapy. 

Asthma outcomes: biomarkers

BACKGROUND

Measurement of biomarkers has been incorporated within clinical research studies of asthma to characterize the population and associate the disease with environmental and therapeutic effects.

OBJECTIVE

National Institutes of Health institutes and federal agencies convened an expert group to propose which biomarkers should be assessed as standardized asthma outcomes in future clinical research studies.

METHODS

We conducted a comprehensive search of the literature to identify studies that developed and/or tested asthma biomarkers. We identified biomarkers relevant to the underlying disease process progression and response to treatment. We classified the biomarkers as either core (required in future studies), supplemental (used according to study aims and standardized), or emerging (requiring validation and standardization). This work was discussed at an National Institutes of Health-organized workshop convened in March 2010 and finalized in September 2011.

RESULTS

Ten measures were identified; only 1, multiallergen screening to define atopy, is recommended as a core asthma outcome. Complete blood counts to measure total eosinophils, fractional exhaled nitric oxide (Feno), sputum eosinophils, urinary leukotrienes, and total and allergen-specific IgE are recommended as supplemental measures. Measurement of sputum polymorphonuclear leukocytes and other analytes, cortisol measures, airway imaging, breath markers, and system-wide studies (eg, genomics, proteomics) are considered as emerging outcome measures.

CONCLUSION

The working group participants propose the use of multiallergen screening in all asthma clinical trials to characterize study populations with respect to atopic status. Blood, sputum, and urine specimens should be stored in biobanks, and standard procedures should be developed to harmonize sample collection for clinical trial biorepositories.

A novel prostacyclin agonist protects against airway hyperresponsiveness and remodeling in mice

Airway remodeling in bronchial asthma results from chronic, persistent airway inflammation. The effects of the reversal of airway remodeling by drug interventions remain to be elucidated. We investigated the effects of ONO-1301, a novel prostacyclin agonist with thromboxane inhibitory activity, on the prevention and reversibility of airway remodeling in an experimental chronic asthma model. Mice sensitized and challenged to ovalbumin (OVA) three times a week for 5 consecutive weeks were administered ONO-1301 or vehicle twice a day from the fourth week of OVA challenges. Twenty-four hours after the final OVA challenge, airway hyperresponsiveness (AHR) was assessed, and bronchoalveolar lavage was performed. Lung specimens were excised for staining to detect goblet-cell metaplasia, airway smooth muscle, and submucosal fibrosis. Mice administered ONO-1301 showed limited increases in AHR compared with mice administered the vehicle. The histological findings of airway remodeling were improved in ONO-1301-treated mice compared with vehicle-treated mice. Presumably, these therapeutic effects of ONO-1301 are attributable to the up-regulation of production of hepatocyte growth factor (HGF) in lung tissue, because the neutralization of HGF by antibodies prevented the effects of ONO-1301 on AHR and airway remodeling. Mice administered ONO-1301 showed similar levels of AHR and airway remodeling as mice administered montelukast, a cysteinyl-leukotriene-1 receptor antagonist, and lower levels were observed in mice administered dexamethasone. These data suggest that ONO-1301 exerts the effect of reversing airway remodeling, at least in part through an elevation of HGF in the lungs, and may be effective as an anti-remodeling drug in the treatment of asthma.

IL-13 dampens human airway epithelial innate immunity through induction of IL-1 receptor-associated kinase M

BACKGROUND

Impaired airway mucosal immunity can contribute to increased respiratory tract infections in asthmatic patients, but the involved molecular mechanisms have not been fully clarified. Airway epithelial cells serve as the first line of respiratory mucosal defense to eliminate inhaled pathogens through various mechanisms, including Toll-like receptor (TLR) pathways. Our previous studies suggest that impaired TLR2 function in T(H)2 cytokine-exposed airways might decrease immune responses to pathogens and subsequently exacerbate allergic inflammation. IL-1 receptor-associated kinase M (IRAK-M) negatively regulates TLR signaling. However, IRAK-M expression in airway epithelium from asthmatic patients and its functions under a T(H)2 cytokine milieu remain unclear.

OBJECTIVES

We sought to evaluate the role of IRAK-M in IL-13-inhibited TLR2 signaling in human airway epithelial cells.

METHODS

We examined IRAK-M protein expression in epithelia from asthmatic patients versus that in normal airway epithelia. Moreover, IRAK-M regulation and function in modulating innate immunity (eg, TLR2 signaling) were investigated in cultured human airway epithelial cells with or without IL-13 stimulation.

RESULTS

IRAK-M protein levels were increased in asthmatic airway epithelium. Furthermore, in primary human airway epithelial cells, IL-13 consistently upregulated IRAK-M expression, largely through activation of phosphoinositide 3-kinase pathway. Specifically, phosphoinositide 3-kinase activation led to c-Jun binding to human IRAK-M gene promoter and IRAK-M upregulation. Functionally, IL-13-induced IRAK-M suppressed airway epithelial TLR2 signaling activation (eg, TLR2 and human β-defensin 2), partly through inhibiting activation of nuclear factor κB.

CONCLUSIONS

Our data indicate that epithelial IRAK-M overexpression in T(H)2 cytokine-exposed airways inhibits TLR2 signaling, providing a novel mechanism for the increased susceptibility of infections in asthmatic patients.

Lipid-cytokine-chemokine cascades orchestrate leukocyte recruitment in inflammation

Chemoattractants are pivotal mediators of host defense, orchestrating the recruitment of immune cells into sites of infection and inflammation. Chemoattractants display vast chemical diversity and include bioactive lipids, proteolytic fragments of serum proteins, and chemokines (chemotactic cytokines). All chemoattractants induce chemotaxis by activating seven-transmembrane-spanning GPCRs expressed on immune cells, establishing the concept that all chemoattractants are related in function. However, although chemoattractants have overlapping functions in vitro, recent in vivo data have revealed that they function, in many cases, nonredundantly in vivo. The chemically diverse nature of chemoattractants contributes to the fine control of leukocyte trafficking in vivo, with sequential chemoattractant use guiding immune cell recruitment into inflammatory sites. Lipid mediators frequently function as initiators of leukocyte recruitment, attracting the first immune cells into tissues. These initial responding immune cells produce cytokines locally, which in turn, induce the local release of chemokines. Local chemokine production then markedly amplifies subsequent waves of leukocyte recruitment. These new discoveries establish a paradigm for leukocyte recruitment in inflammation--described as lipid-cytokine-chemokine cascades--as a driving force in the effector phase of immune responses.

What effect does asthma treatment have on airway remodeling? Current perspectives

Airway remodeling, or structural changes of the airway wall arising from injury and repair, plays an important role in the pathophysiology of asthma. Remodeling is characterized as structural changes involving the composition, content, and organization of many of the cellular and molecular constituents of the bronchial wall. These structural changes can include epithelial injury, subepithelial thickening/fibrosis, airway smooth muscle hyperplasia, goblet cell hypertrophy and hyperplasia, and angiogenesis. Historically, these changes are considered a consequence of long-standing airway inflammation. Recent infant and child studies, however, suggest that remodeling occurs in parallel with inflammation in asthmatic subjects. Despite advancements in the recognition of key cellular and molecular mechanisms involved in remodeling, there remains a paucity of information about which treatments or interactions are most likely to regulate these processes. Furthermore, it is unclear as to when is the best time to initiate treatments to modify remodeling, which components to target, and how best to monitor interventions on remodeling. Indeed, inhaled corticosteroids, which are generally considered to have limited influence on remodeling, have been shown to be beneficial in studies in which the dose and duration of treatment were increased and prolonged, respectively. Moreover, several studies have identified the need to identify novel asthma indices and phenotypes that correlate with remodeling and, as a consequence, might specifically respond to new therapies, such as anti-IgE, anti-IL-5, and anti-TNF-α mAbs. Our review will evaluate the development of remodeling in asthmatic subjects and the effects of treatment on these processes.

A review on herbal antiasthmatics

In traditional systems of medicine, many plants have been documented to be useful for the treatment of various respiratory disorders including asthma. In the last two decades the use of medicinal plants and natural products has been increased dramatically all over the world. Current synthetic drugs used in pharmacotherapy of asthma are unable to act at all the stages and targets of asthma. However some herbal alternatives employed in asthma are proven to provide symptomatic relief and assist in the inhibition of disease progression also. The herbs have shown interesting results in various target specific biological activities such as bronchodilation, mast cell stabilization, anti-anaphylactic, anti-inflammatory, anti-spasmodic, anti-allergic, immunomodulatory and inhibition of mediators such as leukotrienes, lipoxygenase, cyclooxygenase, platelet activating, phosphodiesterase and cytokine, in the treatment of asthma. This paper is an attempt to classify these pharmacological and clinical findings based on their possible mechanism of action reported. It also signifies the need for development of polyherbal formulations containing various herbs acting at particular sites of the pathophysiological cascade of asthma for prophylaxis as well as for the treatment of asthma.

Leukotriene modifiers for asthma treatment

Leukotrienes (LTs), including cysteinyl LTs (CysLTs) and LTB(4) , are potent lipid mediators that have a role in the pathophysiology of asthma. At least two receptor subtypes for CysLTs, CysLT(1) and CysLT(2) , have been identified. The activation of the CysLT(1) receptor is responsible for most of the pathophysiological effects of CysLTs in asthma, including increased airway smooth muscle activity, microvascular permeability, and airway mucus secretion. LTB(4) might have a role in severe asthma, asthma exacerbations, and the development of airway hyperresponsiveness. CysLT(1) receptor antagonists can be given orally as monotherapy in patients with mild persistent asthma, but these drugs are generally less effective than inhaled glucocorticoids. Combination of CysLT(1) receptor antagonists and inhaled glucocorticoids in patients with more severe asthma may improve asthma control and enable the dose of inhaled glucocorticoids to be reduced while maintaining similar efficacy. The identification of subgroups of asthmatic patients who respond to CysLT(1) receptor antagonists is relevant for asthma management as the response to these drugs is variable. CysLT(1) receptor antagonists have a potential anti-remodelling effect that might be important for preventing or reversing airway structural changes in patients with asthma. This review discusses the role of LTs in asthma and the role of LT modifiers in asthma treatment.

Role of Leukotrienes and Leukotriene Modifiers in Asthma

Leukotrienes (LTs), including cysteinyl LTs (CysLTs) and LTB₄, are potent lipid mediators that are pivotal in the pathophysiology of asthma phenotypes. At least two receptor subtypes for CysLTs - CysLT1 and CysLT₂ - have been identified. Most of the pathophysiological effects of CysLTs in asthma, including increased airway smooth muscle activity, microvascular permeability and airway mucus secretion, are mediated by the activation of the CysLT1 receptor. LTB₄ may have a role in the development of airway hyperresponsiveness, severe asthma and asthma exacerbations. Although generally less effective than inhaled glucocorticoids, CysLT₁ receptor antagonists can be given orally as monotherapy in patients with persistent mild asthma. In patients with more severe asthma, CysLT₁ receptor antagonists can be combined with inhaled glucocorticoids. This therapeutic strategy improves asthma control and enables the dose of inhaled glucocorticoids to be reduced, while maintaining similar efficacy. The identification of subgroups of patients with asthma who respond to CysLT₁ receptor antagonists is relevant for asthma management, as the response to these drugs is variable. The potential anti-remodeling effect of CysLT₁ receptor antagonists might be important for preventing or reversing airway structural changes in patients with asthma. This review discusses the role of LTs in asthma and the therapeutic implications of the pharmacological modulation of the LT pathway for asthma.

[Therapy of asthma: anti-inflammatory effects of antileukotrienes]

The antileukotrienes (anti-LT), consisting of synthesis inhibitors and leukotriene receptor antagonists, represent a new direction in targeted drug therapy for asthma. In the present article, the anti-inflammatory properties of anti-LT are briefly summarized. Orally administered anti-LT inhibit the allergen-induced early and late asthmatic reactions and may attenuate the allergen-associated hyperresponsiveness. They also have a remarkable inhaled steroid-sparing effect. In chronic asthma, anti-LT may exert significant therapeutic benefit. In addition to their properties as relievers, anti-LT may have properties as controllers of asthma.

Montelukast and bronchial inflammation in asthma: a randomised, double-blind placebo-controlled trial

BACKGROUND

Examination of bronchoalveolar lavage, induced sputum, and peripheral blood indicate that cysteinyl leukotriene receptor blockers decrease inflammatory cells in asthma but these do not examine airway tissue per se.

OBJECTIVES

Our objective was to determine the effect of montelukast, a leukotriene receptor antagonist, on airway tissue inflammatory cells by direct bronchoscopic examination of the bronchial mucosa.

METHODS

Adult subjects with mild asthma (pre-bronchodilator FEV(1)> or =70% predicted; PC(20) of < or =4 mg/mL) were given 10mg/day oral montelukast (N=38) or placebo (N=37) for 6 weeks. Bronchial mucosal eosinophils and mast cells were identified and counted.

RESULTS

Change from baseline in numbers of biopsy EG2+ ("activated") eosinophils was the primary endpoint; numbers of total (chromotrope 2R+) eosinophils and (tryptase+) mast cells were secondary. Unexpectedly, there were many patients with zero EG2+ eosinophils at baseline. There was a within-group decrease in EG2+ cells, from 13.54 cells/mm (at baseline) to 0.79 cells/mm at 6 weeks in the montelukast group (LS mean change; 95% confidence interval=-13.59 [-25.45, -1.74]cells/mm; P<0.05), a change not observed in the placebo group (-1.17 [-13.26, 10.91]cells/mm; NS). The zero-inflated Poisson statistical model demonstrated that montelukast significantly reduced post-treatment EG2+ cells by 80% compared with placebo (95% CI [70.6-86.8%]; P<0.0001). The data for total eosinophils showed similar changes. The reduction in mast cell numbers was 12% (95% CI [7.9, 16.0]; P<0.0001).

CONCLUSION

Direct examination of airway tissue confirms that montelukast decreases the number of eosinophils and mast cells in asthma.

The role of leukotriene B(4) in allergic diseases

Leukotriene B(4) (LTB(4)) is a lipid mediator with potent chemoattractant properties and that is rapidly generated from activated innate immune cells such as neutrophils, macrophages, and mast cells. Elevated levels of LTB(4) have been reported in various allergic diseases and these levels have been related to disease activity and response to treatment. Recent studies using LTB(4) receptor-1 (BLT1) antagonists or BLT1-deficient mice have revealed that ligation of BLT1 by LTB(4) is important for the activation and recruitment of inflammatory cells including neutrophils, eosinophils, monocytes/macrophages, mast cells, dendritic cells, and more recently, effector T cells to inflamed tissues in various inflammatory diseases. The LTB(4)/BLT1 pathway appears to play an important role in the pathogenesis of severe persistent asthma, aspirin- and exercise-induced asthma, allergic rhinitis, and atopic dermatitis together with other mediators including cysteinyl leukotrienes, cytokines, and chemokines. LTB(4) production is in general resistant to corticosteroid treatment. In fact, corticosteroids can upregulate BLT1 expression on corticosteroid-resistant inflammatory cells such as neutrophils, monocytes, and effector memory CD8+ T cells. As a result, this corticosteroid-resistant LTB(4)/BLT1 pathway may contribute to the development of inflammation in allergic diseases that do not respond to the introduction of corticosteroids. Inhibition of this pathway has potential therapeutic benefit in various allergic diseases that have involvement of corticosteroid-insensitivity.

Leukotriene B4 release from mast cells in IgE-mediated airway hyperresponsiveness and inflammation

Previous studies have shown that leukotriene B4 (LTB4), a proinflammatory lipid mediator, is linked to the development of airway hyperresponsiveness through the accumulation of IL-13-producing CD8+ T cells, which express a high affinity receptor for LTB4, BLT1 (Miyahara et al., Am J Respir Crit Care Med 2005;172:161-167; J Immunol 2005;174:4979-4984). By using leukotriene A4 hydrolase-deficient (LTA4H-/-) mice, which fail to synthesize LTB4, we determined the role of this lipid mediator in allergen-induced airway responses. Two approaches were used. In the first, LTA4H-/- mice and wild-type (LTA4H+/+) mice were systemically sensitized and challenged via the airways to ovalbumin. In the second, mice were passively sensitized with anti-ovalbumin IgE and exposed to ovalbumin via the airways. Mast cells were generated from bone marrow of LTA4H+/+ mice or LTA4H-/- mice. After active sensitization and challenge, LTA4H-/- mice showed significantly lower airway hyperresponsiveness compared with LTA4H+/+ mice, and eosinophil numbers and IL-13 levels in the bronchoalveoloar lavage of LTA4H-/- mice were also significantly lower. LTA4H-/- mice also showed decreased airway reactivity after passive sensitization and challenge. After LTA4H+/+ mast cell transfer, LTA4H-/- mice showed increased airway reactivity after passive sensitization and challenge, but not after systemic sensitization and challenge. These data confirm the important role for LTB4 in the development of altered airway responses and suggest that LTB4 secretion from mast cells is critical to eliciting increased airway reactivity after passive sensitization with allergen-specific IgE.

Expanding roles for leukotrienes in airway inflammation

Leukotrienes (LTs) are lipid mediators derived from the 5-lipoxygenase pathway of arachidonic acid metabolism. Cysteinyl (cys) LTs C(4), D(4), and E(4) are long known to contribute to airway contractile responses via ligation of the cysLT1 receptor, and cysLT1 antagonists are beneficial in some patients with asthma. Research advances over the past several years suggest that cysLT1 also mediates the ability of cysLTs to modulate inflammation, immune responses, and airway remodeling. Although less is known about an additional receptor, cysLT2, emerging evidence indicates that it likely also contributes to cysLT actions promoting inflammation, vascular permeability, and perhaps fibrosis. LTB(4), best known as a neutrophil chemoattractant, is now recognized to exert other important effects contributing to inflammatory and immune responses. These recent data highlight a growing appreciation for LTs as pleiotropic effectors, which are integral components in the network of molecules that mediate the expression of asthma.

The role of LTA4H and ALOX5AP polymorphism in asthma and allergy susceptibility

BACKGROUND

Leukotrienes (LTs) have been identified as central mediators in asthma and allergy. Pharmacological inhibition of cysteinyl-LT activity improves asthma symptoms and control. Accumulating evidence suggests a role for the dihydroxy leukotriene LTB(4) in airway disease. LTA(4) hydrolase and 5-lipoxygenase activating protein have key roles in LTB(4) production. Single nucleotide polymorphism (SNPs) and haplotypes spanning the LTA4H and ALOX5AP genes have been associated with LTB(4) production and myocardial infarction (MI).

OBJECTIVE

To assess the contribution of LTA4H and ALOX5AP polymorphism to asthma and allergy susceptibility.

METHODS

Three hundred and forty-one Caucasian families (two asthmatic siblings) were genotyped for eight SNPs spanning ALOX5AP and five SNPs spanning LTA4H. Association analyses of asthma and related phenotypes (total IgE, atopy, bronchial hyper-responsiveness, FEV(1)) were undertaken using the Family Based Association Test.

RESULTS

Single point analyses identified association (P < 0.05) between SNPs SG13S114, SG13S89, SG13S41 (ALOX5AP), rs1978331 (LTA4H) and asthma and/or related phenotypes. Haplotype analyses using all LTA4H SNPs identified a single key risk haplotype for the development of asthma (P = 0.006) and related phenotypes (P = 0.042-0.005). Haplotype analyses using all ALOX5AP SNPs identified several asthma and atopy risk and protective haplotypes. There was limited correlation with previously identified MI risk haplotypes in both genes. Carriers of both ALOX5AP SG13S41 and LTA4H rs1978331 alleles had an increased risk of developing asthma (OR 2.17, CI 1.41-3.32).

CONCLUSIONS

These data provide evidence for the role of SNPs spanning the ALOX5AP and LTA4H genes in asthma and atopy susceptibility in the Caucasian population and support a role for LTB(4) in disease pathogenesis.

Tissue and BAL based biomarkers in asthma

Asthma is a heterogeneous disease with multiple phenotypes. There are no tissue or bronchoalveolar lavage biomarkers that are "specific" for asthma. Markers associated with eosinophilic, neutrophilic, and paucigranulocytic asthma are discussed here, and those for remodeling. Efforts are to compare tissue and lavage biomarkers with less invasive measures, such as sputum, serum, or exhaled breath, to improve the treatment and management of asthma.

The impact of a medical food containing gammalinolenic and eicosapentaenoic acids on asthma management and the quality of life of adult asthma patients

BACKGROUND

Leukotriene synthesis inhibitors and receptor antagonists are efficacious for the treatment of asthma. Diets containing the fatty acids gammalinolenic acid (GLA) and eicosapentaenoic acid (EPA) decrease leukotriene synthesis; however, their impact on asthma management and quality of life (QOL) has not been evaluated in asthmatic subjects.

OBJECTIVE

To evaluate asthma management and the QOL of asthmatic adult subjects consuming a medical food emulsion containing GLA and EPA.

RESEARCH DESIGN AND METHODS

Trial 1 was a randomized, prospective, double-blind, placebo-controlled, parallel group trial in atopic subjects with mild-to-moderate asthma (n = 35 evaluable) consuming a low dose (0.75 g GLA + 0.5 g EPA), high dose (1.13 g GLA + 0.75 g EPA) or placebo emulsion daily. Subjects were questioned about their asthma management using a non-validated questionnaire after 2 and 4 weeks. Blood leukotrienes were measured at baseline and after 4 weeks. Trial 2 was an open-label study (n = 65 evaluable) where subjects consumed the low-dose medical food emulsion, EFF1009, daily. QOL and asthma management were measured using the validated Mini Asthma Quality of Life (MiniAQLQ) and the Asthma Control (ACQ) questionnaires, respectively, administered at baseline and after 4 weeks.

RESULTS

In Trial 1, leukotriene biosynthesis decreased (p < 0.05). Self-reported asthma status and bronchodilator use improved in subjects consuming low- and high-dose emulsion between week 2 and week 4 (p < 0.01), but not compared to placebo (p > 0.1). In Trial 2, mean +/- standard error total MiniAQLQ and ACQ scores improved by 1.5 +/- 0.2 and 1.0 +/- 0.1, respectively (p < 0.001). Subdomain scores from MiniAQLQ improved and rescue bronchodilator use decreased (p < 0.001).

CONCLUSION

The inclusion of the medical food EFF1009 in asthma management regimens can improve patient quality of life and decrease reliance on rescue medication.

Chronobiology and chronotherapy of allergic rhinitis and bronchial asthma

Study of the chronobiology of allergic rhinitis (AR) and bronchial asthma (BA) and the chronopharmacology and chronotherapy of the medications used in their treatment began five decades ago. AR is an inflammatory disease of the upper airway tissue with hypersensitivity to specific environmental antigens, resulting in further local inflammation, vasomotor changes, and mucus hypersecretion. Symptoms include sneezing, nasal congestion, and runny and itchy nose. Approximately 25% of children and 40% of adults in USA are affected by AR during one or more seasons of the year. The manifestation and severity of AR symptoms exhibit prominent 24-h variation; in most persons they are worse overnight or early in the morning and often comprise nighttime sleep, resulting in poor daytime quality of life, compromised school and work performance, and irritability and moodiness. BA is also an inflammatory medical condition of the lower airways characterized by hypersensitivity to specific environmental antigens, resulting in greater local inflammation as well as bronchoconstriction, vasomotor change, and mucus hypersecretion. In USA an estimated 6.5 million children and 15.7 million adults have BA. The onset and worsening of BA are signaled by chest wheeze and/or croupy cough and difficult and labored breathing. Like AR, BA is primarily a nighttime medical condition. AR is treated with H1-antagonist, decongestant, and anti-inflammatory (glucocorticoid and leukotriene receptor antagonist and modifier) medications. Only H1-antagonist AR medications have been studied for their chronopharmacology and potential chronotherapy. BA is treated with some of the same medications and also theophylline and beta2-agonists. The chronopharmacology and chronotherapy of many classes of BA medications have been explored. This article reviews the rather extensive knowledge of the chronobiology of AR and BA and the chronopharmacology and chronotherapy of the various medications used in their treatment.

Zileuton: clinical implications of 5-Lipoxygenase inhibition in severe airway disease

The 5-Lipoxygenase pathway results in the formation of leukotrienes, including leukotriene B(4) (LTB(4)), 5-oxo-6E,8Z,11Z,14Z-eicosatetranoic acid and the cysteinyl leukotrienes (LTC(4), LTD(4) and LTE(4)) and activates all four leukotriene receptors, BLT1, BLT2, cysLT(1) and cysLT(2). Zileuton is the only commercially available inhibitor of the 5-Lipoxygenase pathway. In a number of clinical trials, zileuton has been shown to improve airway function and inflammation, asthma symptom control and quality of life in asthmatics. Given the important role that leukotrienes play in airway inflammation, zileuton provides an additional therapeutic option in the management of chronic, persistent asthma, particularly those asthmatics with more severe disease. In addition, zileuton has shown promise in a number of other conditions, including upper airway inflammatory conditions, dermatological disease and chronic obstructive pulmonary disease. The development of new formulations, including a controlled release tablet formulation for b.i.d. dosing and an intravenous preparation for acute asthma exacerbations may enhance clinical utility and expand therapeutic indications.

Exhaled bronchial cysteinyl leukotrienes in allergic patients

PURPOSE OF REVIEW

To review the current knowledge of noninvasive monitoring of allergic airway inflammation by analysis of leukotrienes in the exhaled breath condensate.

RECENT FINDINGS

Treatment of respiratory allergies involves chronic treatment based on clinical symptoms and pulmonary function tests. Evaluation of local inflammation would be desirable but is currently not feasible because of the difficulty in sampling the airways. Recently, exhaled breath condensate collection and analysis has polarized much interest in the respiratory field. Although some methodological issues are still under scrutiny, airways inflammatory markers can be assayed with this technique. In particular, exhaled breath condensate leukotrienes have been thoroughly investigated in the setting of bronchial asthma and allergic rhinitis in adults and children. Exhaled leukotrienes are increased in patients with asthma and rhinitis during the pollen season, correlate with exacerbations and asthma severity, and are reduced by specific anti-inflammatory treatment and allergen avoidance.

SUMMARY

Some issues still prevent the use of exhaled breath condensate in clinical practice but in the research setting it has been proved to be useful for noninvasive monitoring of allergic inflammation in the lung. In particular, exhaled leukotrienes may represent valuable biomarkers for diagnostic and therapeutic purposes in allergic patients.

Nocturnal asthma

PURPOSE OF REVIEW

To examine recent advancements of the epidemiology, pathophysiology, and treatment of nocturnal asthma.

RECENT FINDINGS

In a large cross-sectional survey, the prevalence of nocturnal symptoms was 60%. Forty-two percent of patients who completed the study did not declare nocturnal symptoms that were detected by physicians. A recent study including 47 individuals with nocturnal and nonnocturnal asthma showed that allele genotype Gly16 was significantly higher in the nocturnal asthma group (72%) compared with the nonnocturnal asthma group (54%). A randomized double-blind study of nocturnal asthma with esomeprazole improved the peak expiratory flow rate in individuals with both nocturnal asthma and gastroesophageal reflux disease. Of patients with nocturnal asthma and snoring, 48% had obstructive sleep apnea. After continuous positive airway pressure treatment, there was significant improvement of asthma nighttime symptom scores; however, no significant difference in lung functions was observed.

SUMMARY

Nocturnal symptoms in asthma are frequently underdiagnosed. Obstructive sleep apnea may be prevalent in nocturnal asthma. The Gly16 polymorphism of the beta2-receptor is common in nocturnal asthma. Gastric suppression treatment in patients with both gastroesophageal reflux disease and nocturnal asthma improved the peak expiratory flow rate. Continuous positive airway pressure improves nocturnal symptoms but not lung function tests.

The expanding role of leukotriene receptor antagonists in chronic asthma

OBJECTIVE

To provide a comprehensive review of studies that evaluate the effects of leukotriene receptor antagonists in adult chronic asthma.

DATA SOURCES

A literature search using MEDLINE, Clinical Evidence, and the Cochrane Library was performed using the following keywords: randomized controlled trial, asthma, cysteinyl leukotriene, leukotriene receptor antagonist, antileukotriene, montelukast, zafirlukast, pranlukast, inflammation, lung function, exacerbations, and symptoms.

STUDY SELECTION

Relevant peer-reviewed articles (mostly randomized controlled trials, meta-analyses, and reviews) published up to July 2006 were selected and extracted.

RESULTS

Leukotriene receptor antagonists are beneficial across a range of asthma severities and may have a particular role in exercise-induced asthma, aspirin-sensitive asthma, and individuals with concomitant allergic rhinitis.

CONCLUSION

In the management of chronic asthma, leukotriene receptor antagonists have emerged as a useful oral nonsteroidal anti-inflammatory adjunct both as monotherapy and in combination with other classes of drugs. Monitoring their effects in terms of lung function alone may result in clinicians missing beneficial effects on inflammatory biomarkers, airway hyperresponsiveness, and exacerbations.

CD8+ T lymphocytes and leukotriene B4: novel interactions in the persistence and progression of asthma

The contribution of CD8+ T cells to the development of airway hyperresponsiveness and airway inflammation has received increased attention recently. CD8+ T cells, which are capable of secreting TH2 cytokines, including IL-4, IL-5, and IL-13, have been described in asthmatic subjects and in animals sensitized and challenged with allergen. A subset of these IL-13-producing CD8+ T cells, effector memory CD8+ T cells in the mouse, express a high-affinity receptor for leukotriene B4 (BLT1), and expression of this receptor is essential for their accumulation in the lung and development of airway hyperresponsiveness and airway inflammation. A similar subset of CD8+/BLT1+/IL-13+ T cells has also been identified in the bronchoalveolar lavage fluid of asthmatic subjects, suggesting a pathogenic role for this unique subset of CD8+ T cells in asthma.

Role of the LTB4/BLT1 pathway in allergen-induced airway hyperresponsiveness and inflammation

LTB4, a proinflammatory lipid mediator generated from arachidonic acid through the action of 5-lipoxygenase, has been known for over two decades and is implicated in a wide variety of inflammatory disorders. BLT1, a G-protein-coupled receptor, has recently been identified as a high affinity receptor specific for LTB4. Recent studies in allergen-induced airway hyperresponsiveness and inflammation using mice lacking BLT1 have shown crucial new roles for leukotriene B4 and BLT1 in Th2 cytokine IL-13 production from lung T cells and recruitment of antigen-specific effector CD8+ T cells, suggesting novel mechanisms for their actions. The leukotriene B4-BLT1 pathway is an important target for the treatment of bronchial asthma.

The leukotriene B4 receptor (BLT1) is required for effector CD8+ T cell-mediated, mast cell-dependent airway hyperresponsiveness

Studies in both humans and rodents have suggested that CD8+ T cells contribute to the development of airway hyperresponsiveness (AHR) and that leukotriene B4 (LTB4) is involved in the chemotaxis of effector CD8+ T cells (T(EFF)) to the lung by virtue of their expression of BLT1, the receptor for LTB4. In the present study, we used a mast cell-CD8-dependent model of AHR to further define the role of BLT1 in CD8+ T cell-mediated AHR. C57BL/6+/+ and CD8-deficient (CD8-/-) mice were passively sensitized with anti-OVA IgE and exposed to OVA via the airways. Following passive sensitization and allergen exposure, C57BL/6+/+ mice developed altered airway function, whereas passively sensitized and allergen-exposed CD8-/- mice failed to do so. CD8-/- mice reconstituted with CD8+ T(EFF) developed AHR in response to challenge. In contrast, CD8-/- mice reconstituted with BLT1-deficient effector CD8+ T cells did not develop AHR. The induction of increased airway responsiveness following transfer of CD8+ T(EFF) or in wild-type mice could be blocked by administration of an LTB4 receptor antagonist confirming the role of BLT1 in CD8+ T cell-mediated AHR. Together, these data define the important role for mast cells and the LTB4-BLT1 pathway in the development of CD8+ T cell-mediated allergic responses in the lung.

Allergic rhinitis: impact of the disease and considerations for management

AR is a common condition affecting individuals of all ages. Those afflicted with AR often suffer from associated inflammatory conditions of the mucosa,such as AC, rhinosinusitis, asthma, otitis media with effusion, and other atopic conditions, such as eczema and food allergies. Lack of treatment or treatment with suboptimal therapy may result in reduced quality of life and compromise productivity at work or school. Although environmental controls may prove difficult to implement, and not all controls appear adequately to mitigate symptoms of AR, they continue to represent a foundation for treatment. Many different classes of medications are now available, and they have been shown to be effective and safe in a large number of well-designed, double-blind, placebo-controlled clinical trials. Some of the over-the-counter medi-cations have been associated with increased sedation, potentially leading to accidents and fatalities at work or while operating complex machinery, such as automobiles. Only immunotherapy with increasing doses of individually targeted allergens results in sustained changes in the immune system. Although anti-IgE is probably only the first successful immunomodulator commercially available to treat AR, monoclonal antibodies will remain too costly, at least in the near future, to find their way into routine AR treatment.

CNS determinants of sleep-related worsening of airway functions: implications for nocturnal asthma

This review summarizes the recent neuroanatomical and physiological studies that form the neural basis for the state-dependent changes in airway resistance. Here, we review only the interactions between the brain regions generating quiet (non-rapid eye movement, NREM) and active (rapid eye movement, REM) sleep stages and CNS pathways controlling cholinergic outflow to the airways. During NREM and REM sleep, bronchoconstrictive responses are heightened and conductivity of the airways is lower as compared to the waking state. The decrease in conductivity of the lower airways parallels the sleep-induced decline in the discharge of brainstem monoaminergic cell groups and GABAergic neurons of the ventrolateral periaqueductal midbrain region, all of which provide inhibitory inputs to airway-related vagal preganglionic neurons (AVPNs). Withdrawal of central inhibitory influences to AVPNs results in a shift from inhibitory to excitatory transmission that leads to an increase in airway responsiveness, cholinergic outflow to the lower airways and consequently, bronchoconstriction. In healthy subjects, these changes are clinically unnoticed. However, in patients with bronchial asthma, sleep-related alterations in lung functions are troublesome, causing intensified bronchopulmonary symptoms (nocturnal asthma), frequent arousals, decreased quality of life, and increased mortality. Unquestionably, the studies revealing neural mechanisms that underlie sleep-related alterations of airway function will provide new directions in the treatment and prevention of sleep-induced worsening of airway diseases.