The role of leukotrienes in asthma

Lipids in Equine Airway Inflammation: An Overview of Current Knowledge

Mild-moderate and severe equine asthma (MEA and SEA) are prevalent inflammatory airway conditions affecting horses of numerous breeds and disciplines. Despite extensive research, detailed disease pathophysiology and the differences between MEA and SEA are still not completely understood. Bronchoalveolar lavage fluid cytology, broadly used in clinical practice and in equine asthma research, has limited means to represent the inflammatory status in the lower airways. Lipidomics is a field of science that can be utilized in investigating cellular mechanisms and cell-to-cell interactions. Studies in lipidomics have a broad variety of foci, of which fatty acid and lipid mediator profile analyses and global lipidomics have been implemented in veterinary medicine. As many crucial proinflammatory and proresolving mediators are lipids, lipidomic studies offer an interesting yet largely unexplored means to investigate inflammatory reactions in equine airways. The aim of this review article is to collect and summarize the findings of recent lipidomic studies on equine airway inflammation.

Lipid species profiling of bronchoalveolar lavage fluid cells of horses housed on two different bedding materials

The lipidome of equine BALF cells has not been described. The objectives of this prospective repeated-measures study were to explore the BALF cells' lipidome in horses and to identify lipids associated with progression or resolution of airway inflammation. BALF cells from 22 horses exposed to two bedding materials (Peat 1-Wood shavings [WS]-Peat 2) were studied by liquid chromatography-tandem mass spectrometry (LC-MS/MS). The effects of bedding on lipid class and species compositions were tested with rmANOVA. Correlations between lipids and cell counts were examined. The BALF cells' lipidome showed bedding-related differences for molar percentage (mol%) of 60 species. Whole phosphatidylcholine (PC) class and its species PC 32:0 (main molecular species 16:0_16:0) had higher mol% after Peat 2 compared with WS. Phosphatidylinositol 38:4 (main molecular species 18:0_20:4) was higher after WS compared with both peat periods. BALF cell count correlated positively with mol% of the lipid classes phosphatidylserine, sphingomyelin, ceramide, hexosylceramide, and triacylglycerol but negatively with PC. BALF cell count correlated positively with phosphatidylinositol 38:4 mol%. In conclusion, equine BALF cells' lipid profiles explored with MS-based lipidomics indicated subclinical inflammatory changes after WS. Inflammatory reactions in the cellular lipid species composition were detected although cytological responses indicating inflammation were weak.

Caffeic acid modulates activation of neutrophils and attenuates sepsis-induced organ injury by inhibiting 5-LOX/LTB4 pathway

BACKGROUND

Sepsis is a critical systemic inflammatory syndrome which usually leads to multiple organ dysfunction. Caffeic acid (CA), a phenolic compound derived from various plants, has been proved to be essential in neuroprotection, but its role in septic organ damage is unclear. This research aimed to investigate whether CA protects against organ injury in a mouse model of cecal ligation and puncture (CLP).

METHODS

CA (30 mg/kg) or vehicle was administered by intraperitoneal injection immediately after CLP. The samples of blood, lungs, and livers were collected 24 h later. Organ injury was assessed by histopathological examination (HE staining), neutrophil infiltration (myeloperoxidase fluorescence), oxidative stress levels (MDA, SOD, HO-1), and inflammatory cytokines (TNF-α, IL-1β, and IL-6) release in lung and liver tissues. Neutrophil extracellular trap (NET) formation was analyzed by immunofluorescence. In vitro experiments were performed to investigate the potential mechanisms of CA using small interfering RNA (siRNA) techniques in neutrophils, and the effect of CA on neutrophil apoptosis was analyzed by flow cytometry.

RESULTS

Results showed that CA treatment improved the 7-day survival rate and attenuated the histopathological injury in the lung and liver of CLP mice. CA significantly reduced neutrophil infiltration in the lungs and livers of CLP mice. TNF-α, IL-1β, IL-6 and LTB4 were reduced in serum, lung, and liver of CA-treated CLP mice, and phosphorylation of MAPK (p38, ERK, JNK) and p65 NF-κB was inhibited in lungs and livers. CA treatment further increased HO-1 levels and enhanced superoxide dismutase (SOD) activity, but reduced malondialdehyde (MDA) levels and NET formation. Similarly, in vitro experiments showed that CA treatment and 5-LOX siRNA interference inhibited inflammatory activation and NET release in neutrophils, suppressed MAPK and NF-κB phosphorylation in LPS-treated neutrophils, and decreased LTB4 and cfDNA levels. Flow cytometric analysis revealed that CA treatment reversed LPS-mediated delayed apoptosis in human neutrophils, and Western blot also indicated that CA treatment inhibited Bcl-2 expression but increased Bax expression. CA treatment did not induce further changes in neutrophil apoptosis, inflammatory activation, and NET release when 5-LOX was knocked down by siRNA interference.

CONCLUSIONS

CA has a protective effect on lung and liver injury in a murine model of sepsis, which may be related to inhibition of the 5-LOX/LTB4 pathway.

A combination of LCPUFAs regulates the expression of miRNA-146a-5p in a murine asthma model and human alveolar cells

BACKGROUND

LCPUFAs are suggestive of having beneficial effects on inflammatory diseases such as asthma. However, little is known about the modulative capacity of omega-(n)-3 and n-6 LCPUFAs within the epigenetic regulation of inflammatory processes.

OBJECTIVE

The aim of this study was to investigate whether a specific combined LCPUFA supplementation restores disease-dysregulated miRNA-profiles in asthmatic mice. In addition, we determined the effect of the LCPUFA supplementation on the interaction of the most regulated miRNA expression and oxygenase activity in vitro.

METHODS

Sequencing of miRNA was performed by NGS from lung tissue of asthmatic and control mice with normal diet, as well as of LCPUFA supplemented asthmatic mice. Network analysis and evaluation of the biological targets of the miRNAs were performed by DIANA- miRPath v.3 webserver software, TargetScanMouse 7.2, and tool String v.10, respectively. Expression of hsa-miRNA-146a-5p and activity of COX-2 and 5-LO in LCPUFA-treated A549 cells were assessed by qPCR and flow cytometry, respectively.

RESULTS

In total, 62 miRNAs were dysregulated significantly in murine allergic asthma. The LCPUFA combination restored 21 of these dysregulated miRNAs, of which eight (mmu-miR-146a-5p, -30a-3p, -139-5p, -669p-5p, -145a-5p, -669a-5p, -342-3p and -15b-5p) were even normalized compared to the control levels. Interestingly, six of the eight rescued miRNAs are functionally implicated in TGF-β signaling, ECM-receptor interaction and fatty acid biosynthesis. Furthermore, in vitro experiments demonstrated that upregulation of hsa-miRNA-146a-5p is accompanied by a reduction of COX-2 and 5-LO activity. Moreover, transfection experiments revealed that LCPUFAs inhibit 5-LO activity in the presence and absence of anti-miR-146a-5p.

CONCLUSION

Our results demonstrate the modulative capacity of LCPUFAs on dysregulated miRNA expression in asthma. In addition, we pointed out the high regulative potential of LCPUFAs on 5-LO regulation and provided evidence that miR-146a partly controls the regulation of 5-LO.

miR-146a suppresses 5-lipoxygenase activating protein (FLAP) expression and Leukotriene B4 production in lung cancer cells

Arachidonic acid (AA) can be converted into prostaglandins (PGs) or leukotrienes (LTs) by the enzymatic actions of cyclooxygenases (COX-1 and COX-2) or 5-lipoxygenase (5-LO), respectively. PGs and LTs are lipid signaling molecules that have been implicated in various diseases, including multiple cancers. 5-LO and its activating protein (FLAP) work together in the first two conversion steps of LT production. Previous work has suggested a role for LTs in cancer development and progression. MicroRNAs (miRNAs) are small RNA molecules that negatively regulate gene expression post-transcriptionally, and have previously been shown to be involved in cancer. Here, we show that high FLAP expression is associated with lower overall survival in lung adenocarcinoma patients, and FLAP protein is overexpressed in lung cancer cells compared to normal lung cells. Our lab has previously shown that miR-146a regulates COX-2 in lung cancer cells, and this miRNA is also predicted to target FLAP. Transient and stable transfections of miR-146a repress endogenous FLAP expression in lung cancer cells, and reporter assays show this regulation occurs through a direct interaction between the FLAP 3′ untranslated region (UTR) and miR-146a. Restoration of miR-146a also results in decreased cancer cell Leukotriene B4 (LTB₄) production. Additionally, methylation analysis indicates the miR-146a promoter is hypermethylated in lung cancer cell lines. Taken together, this study and previous work from our lab suggest miR-146a is an endogenous dual inhibitor of AA metabolism in lung cancer cells by regulating both PG and LT production through direct targeting of the COX-2 and FLAP 3’ UTRs.

Zileuton alleviates acute cisplatin nephrotoxicity: Inhibition of lipoxygenase pathway favorably modulates the renal oxidative/inflammatory/caspase-3 axis

OBJECTIVE

The current study investigated for the first time the possible beneficial effect of zileuton, a selective 5-lipoxygenase inhibitor (5-LOX), against cisplatin-induced acute renal failure.

METHODOLOGY

Male Sprague-Dawley rats (180-200 g) were administered cisplatin once (5 mg/kg, i.p.) alone or combined with oral zileuton (10 mg/kg, given twice; 1 h before and 12 h after cisplatin).

RESULTS

Compared with control rats, acute cisplatin administration caused significant increases of BUN (33.76 ± 7.74 vs 61.88 ± 11.35 mg/dl), serum creatinine (0.61 ± 0.21 vs 1.56 ± 0.28 mg/dl), renal levels of MDA (6.40 ± 1.04 vs 20.52 ± 2.18 nmol/g tissue), NOx (3.45 ± 1.20 vs 17.70 ± 2.27 nmol/g tissue), TNF-α (6.71 ± 0.66 vs 23.71 ± 3.41 pg/g tissue), MPO (0.87 ± 0.09 vs 3.12 ± 0.41 U/mg tissue protein) and renal caspase-3 activity (2.81 ± 0.37 vs 12.70 ± 2.94 U/mg tissue protein). Whereas, total SOD activity (1.99 ± 0.53 vs 0.79 ± 0.06 U/mg tissue protein) and IL-10 (110.98 ± 19.70 vs 62.34 ± 14.42 pg/g tissue) were significantly decreased. Cisplatin-induced nephrotoxicity was further confirmed histopathologically (tubular necrosis, cystic dilatation of renal tubules, vacuolar degeneration of renal tubular epithelium with perivascular oedema, and interstitial fibrosis). These changes were accompanied by alteration in 5-LOX pathway manifested as elevated renal levels of 5-LOX, LTD4 and LTB4. Simultaneous administration of zileuton to the cisplatin-treated rats reversed the deleterious renal insults and restored the measured parameters near to control values.

CONCLUSIONS

These data establish the first experimental evidence that zileuton abrogates cisplatin nephrotoxicity in rats probably via the inhibition of detrimental actions of 5-LOX products, thus favorably affecting renal oxidative/inflammatory/caspase-3 axis. Based on current findings, the therapeutic prospect of zileuton for this purpose is recommended.

SKI3301, a purified herbal extract from Sophora tonkinensis, inhibited airway inflammation and bronchospasm in allergic asthma animal models in vivo

ETHNOPHARMACOLOGICAL RELEVANCE

Sophora tonkinensis (Leguminosae, ST) is a traditional herbal plant in Korea and China. Its roots and rhizomes have been used to dissipate heat, to clear toxic material and to treat acute pharyngolaryngeal infections and sore throats.

AIM OF STUDY

In this study, we tried to investigate the anti-inflammatory and anti-asthmatic effects of a purified extract (SKI3301) from Sophora tonkinensis using in vitro enzyme assay models and ovalbumin (OVA)-induced asthma animal models.

MATERIALS AND METHODS

The effect of SKI3301 on pro-inflammatory enzymes such as 5-lipoxygenase, phosphodiesterase 3 & 4, and thromboxane synthase was assayed in vitro. BALB/c mice were sensitized with OVA/Alum ip injection and nebulized with OVA to induce airway inflammation. Bronchoalveolar lavage (BAL) fluid was collected and analyzed for leukocytes infiltration and IL-5 production along with lung histopathology. Guinea pigs passively sensitized with anti-OVA antiserum were used to investigate the effect of SKI3301 on bronchospasm in vitro and in vivo.

RESULTS

SKI3301 potently inhibited the activities of 5-lipoxygenase, phosphodiesterase 3 & 4, and thromboxane synthase. Orally administered SKI3301 attenuated the total leukocytes and eosinophil infiltration and IL-5 level in BAL fluids. Histopathological changes associated with lung inflammation were also reduced by SKI3301. SKI3301 inhibited OVA-induced contraction of isolated trachea from sensitized guinea pigs. SKI3301 also protected OVA-induced bronchoconstriction in the sensitized guinea pigs. Maackiain, one of 3 major components of SKI3301, was effective in inhibiting 5-lipoxygenase and OVA-induced airway inflammation.

CONCLUSION

In this study, SKI3301 potently inhibited pro-inflammatory enzymes and attenuated OVA-induced bronchospasm in animal model of allergic asthma. These results suggest that SKI3301 may have therapeutic potential for allergic asthma.

Troglitazone, a PPAR-γ agonist, decreases LTC4 concentration in mononuclear cells in patients with asthma

BACKGROUND

Asthma is an inflammatory disorder with multiple mediators involved in the inflammatory response. Despite several attempts, no new anti-inflammatory drugs have been registered for asthma treatment for several years. However, thiazolidinediones, peroxisome proliferator-activated receptor agonists, have demonstrated some anti-inflammatory properties in various experimental settings. The aim of this study was to assess the influence of troglitazone on LTC₄ and 15-HETE concentrations. It also evaluates TNF-induced eotaxin synthesis in peripheral blood mononuclear cells from 14 patients with mild asthma and 13 healthy controls.

METHODS

PBMCs were isolated from the whole blood of the asthmatics and healthy subjects and pretreated with 0.1, 1 or 10μM of Troglitazone. The cells were then exposed to 10^-6M calcium jonophore or 10ng/ml TNF. The production and release of LTC₄, 15-HETE and eotaxin were then assessed.

RESULTS

Troglitazone caused a dose-dependent inhibition in LTC₄ synthesis in both asthmatics and healthy subjects. Troglitazone did not influence 15-HETE or eotaxin production in either asthmatic patients or in healthy individuals.

CONCLUSION

Due to its inhibition of LTC₄ synthesis, troglitazone therapy is an interesting potential therapeutic approach in asthma and other LTC₄ related inflammatory disorders.

Patient stratification and the unmet need in asthma

Asthma is often described as an inflammatory disease of the lungs and in most patients symptomatic treatment with bronchodilators or inhaled corticosteroids is sufficient to control disease. Unfortunately there are a proportion of patients who fail to achieve control despite treatment with the best current treatment. These severe asthma patients have been considered a homogeneous group of patients that represent the unmet therapeutic need in asthma. Many novel therapies have been tested in unselected asthma patients and the effects have often been disappointing, particularly for the highly specific monoclonal antibody-based drugs such as anti-IL-13 and anti-IL-5. More recently, it has become clear that asthma is a syndrome with many different disease drivers. Clinical trials of anti-IL-13 and anti-IL-5 have focused on biomarker-defined patient groups and these trials have driven the clinical progression of these drugs. Work on asthma phenotyping indicates that there is a group of asthma patients where T helper cell type 2 (Th2) cytokines and inflammation predominate and these type 2 high (T2-high) patients can be defined by biomarkers and response to therapies targeting this type of immunity, including anti-IL-5 and anti-IL-13. However, there is still a subset of T2-low patients that do not respond to these new therapies. This T2-low group will represent the new unmet medical need now that the T2-high-targeting therapies have made it to the market. This review will examine the current thinking on patient stratification in asthma and the identification of the T2-high subset. It will also look at the T2-low patients and examine what may be the drivers of disease in these patients.

Montelukast medicines of today and tomorrow: from molecular pharmaceutics to technological formulations

Montelukast sodium is a leukotriene antagonist of growing interest as an alternative therapy for asthma across different age groups due to its bronchoprotective, anti-inflammatory and anti-allergic properties. Currently, montelukast is commercialized only in oral solid dosage forms, which are the favorite of adult patients but may pose challenges in administration to children of young age or patients suffering from dysphagia. This review presents a comprehensive revision of scientific reports and patents on emerging strategies for the delivery of montelukast. A common ground to these reports is the pursue of an enhanced montelukast performance, by increasing its bioavailability and physico-chemical stability. A wide variety of strategies can be found, from the formation of supramolecular adducts with cyclodextrins to encapsulation in nanoparticles and liposomes. The new dosage forms for montelukast are designed for non-enteric absorption, some for absorption in the oral cavity and another two being for local action in the nasal mucosa or in the pulmonary epithelium. The review describes the emerging delivery strategies to circumvent the current limitations to the use of montelukast that are expected to ultimately lead to the development of more patient-compliant dosage forms.

Indole based peptidomimetics as anti-inflammatory and anti-hyperalgesic agents: Dual inhibition of 5-LOX and COX-2 enzymes

The indoles bearing a tosyl group at N-1 and a dipeptide substituent at C-3 were screened for anti-inflammatory and anti-hyperalgesic activities. Some of the compounds made significant reduction in the dextran induced swelling and capsaicin induced pain in the albino mice. About 95% reversal in capsaicin induced pain occurred in the presence of 5 mg kg(-1) of compound 7b, 7d and 7h while diclofenac showed 90% reversal when its 10 mg kg(-1) dose was used. In order to examine the mode of action of these compounds; COX-1, COX-2 and 5-LOX enzyme immunoassays were performed. The IC50 of compound 7b for COX-2 and 5-LOX were in the nM range: 5-LOX, IC50 = 2.0 nM; COX-2, IC50 = 6.3 nM, selectivity for COX-2 over COX-1 was 351. The interactions of the compounds with COX-2 and 5-LOX were supported by the physical parameters including Ki, Ka and ΔG. The most potent compounds 7b, 7d and 7h showed no toxicity to the animals and were identified as the promising leads for anti-inflammatory drugs.

Cysteinyl leukotriene receptor-1 antagonists as modulators of innate immune cell function

Cysteinyl leukotrienes (cysLTs) are produced predominantly by cells of the innate immune system, especially basophils, eosinophils, mast cells, and monocytes/macrophages. Notwithstanding potent bronchoconstrictor activity, cysLTs are also proinflammatory consequent to their autocrine and paracrine interactions with G-protein-coupled receptors expressed not only on the aforementioned cell types, but also on Th2 lymphocytes, as well as structural cells, and to a lesser extent neutrophils and CD8⁺ cells. Recognition of the involvement of cysLTs in the immunopathogenesis of various types of acute and chronic inflammatory disorders, especially bronchial asthma, prompted the development of selective cysLT receptor-1 (cysLTR1) antagonists, specifically montelukast, pranlukast, and zafirlukast. More recently these agents have also been reported to possess secondary anti-inflammatory activities, distinct from cysLTR1 antagonism, which appear to be particularly effective in targeting neutrophils and monocytes/macrophages. Underlying mechanisms include interference with cyclic nucleotide phosphodiesterases, 5′-lipoxygenase, and the proinflammatory transcription factor, nuclear factor kappa B. These and other secondary anti-inflammatory mechanisms of the commonly used cysLTR1 antagonists are the major focus of the current review, which also includes a comparison of the anti-inflammatory effects of montelukast, pranlukast, and zafirlukast on human neutrophils in vitro, as well as an overview of both the current clinical applications of these agents and potential future applications based on preclinical and early clinical studies.

Addition of a 5-lipoxygenase-activating protein inhibitor to an inhaled corticosteroid (ICS) or an ICS/long-acting beta-2-agonist combination in subjects with asthma

OBJECTIVE

To investigate the clinical benefits of 'add-on' therapy with GSK2190915 in combination with the inhaled corticosteroid (ICS) fluticasone propionate (FP) and the ICS/long-acting beta 2 agonist (LABA) combination FP/salmeterol in asthmatic subjects.

METHODS

Both studies were cross-over, randomized, double-blind, double-dummy and placebo-controlled in subjects with a forced expiratory volume in 1 second (FEV1) best of >50 and ≤80% of predicted. Add-on to ICS: Subjects (n = 162) aged ≥12 years received FP 100 µg twice daily (BID) plus GSK2190915 100 mg once daily (QD); GSK2190915 300 mg QD; montelukast 10 mg QD; salmeterol 50 µg BID or placebo. Add-on to ICS/LABA: Female subjects (n = 145) aged ≥18 years received FP/salmeterol 250/50 µg BID plus GSK2190915 300 mg QD, montelukast 10 mg QD or placebo. In both studies, the primary endpoint was trough FEV1 at the end of the treatment period. Secondary endpoints included a range of objective and patient-reported measures of efficacy.

RESULTS

Add-on to ICS: There was no statistically significant difference in the primary endpoint between either dose of GSK2190915 (add-on to FP) and placebo. Nominally statistically significant increases were demonstrated for GSK2190915 300 mg add-on relative to placebo for mean morning peak expiratory flow (p = 0.049), percentage of symptom-free days (p = 0.035) and percentage of symptom-free 24 h periods (p = 0.030). Add-on to ICS/LABA: There were no statistically significant differences on the primary endpoint between treatment regimens. Nominally statistically significant decreases were demonstrated in daytime (p = 0.023), night-time (p = 0.041) and 24 h (p = 0.019) short-acting beta 2 agonist usage with FP/salmeterol + GSK2190915 300 mg vs. FP/salmeterol + placebo.

CONCLUSION

There was no clinically significant improvement in the primary endpoint following GSK2190915 add-on treatment; however, improvements in a range of secondary endpoints and biomarker data provided evidence of pharmacological activity. Improvements in response to background treatment may have been a limitation in both studies.

TRIAL REGISTRATION

Clinicaltrials.gov identifiers: NCT01156792 and NCT01248975.

A review on leukotrienes and their receptors with reference to asthma

OBJECTIVE AND METHODS

Leukotrienes (LTs) including cysteinyl leukotrienes (CysLTs) and LTB4 are the most potent inflammatory lipid mediators and play a central role in the pathophysiology of asthma and other inflammatory diseases. These biological molecules mediate a plethora of contractile and inflammatory responses through specific interaction with distinct G protein-coupled receptors (GPCRs). The main objective of this review is to present an overview of the biological effects of CysLTs and their receptors, along with the current knowledge of mechanisms and role of LTs in the pathogenesis of asthma.

RESULTS

CysLTs including LTC4, LTD4 and LTE4 are ligands for CysLT1 and CysLT2 receptors, and LTB4 is the agonist for BLT1 and BLT2 receptors. The role of CysLT1 receptor is well established, and most of the pathophysiological effects of CysLTs in asthma are mediated by CysLT1 receptor. Several CysLT1 antagonists have been developed to date and are currently in clinical practice. Most common among them are classical CysLT1 receptor antagonists such as montelukast, zafirlukast, pranlukast, pobilukast, iralukast, cinalukast and MK571. The pharmacological role of CysLT2 receptor, however, is less defined and there is no specific antagonist available so far. The recent demonstration that mice lacking both known CysLT receptors exhibit full/augmented response to CysLT points to the existence of additional subtypes of CysLT receptors. LTB4, on the other hand, is another potent inflammatory leukotriene, which acts as a strong chemoattractant for neutrophils, but weaker for eosinophils. LTB4 is known to play an important role in the development of airway hyper-responsiveness in severe asthma. However there is no LTB4 antagonist available in clinic to date.

CONCLUSION

This review gives a recent update on the LTs including their biosynthesis, biological effects and the role of anti-LTs in the treatment of asthma. It also discusses about the possible existence of additional subtypes of CysLT receptors.

Efficacy, safety and tolerability of GSK2190915, a 5-lipoxygenase activating protein inhibitor, in adults and adolescents with persistent asthma: a randomised dose-ranging study

Background

GSK2190915 is a high affinity 5-lipoxygenase-activating protein inhibitor being developed for the treatment of asthma. The objective of this study was to evaluate GSK2190915 efficacy, dose–response and safety in subjects with persistent asthma treated with short-acting beta2-agonists (SABAs) only.

Methods

Eight-week multicentre, randomised, double-blind, double-dummy, stratified (by age and smoking status), parallel-group, placebo-controlled study in subjects aged ≥12 years with a forced expiratory volume in 1 second (FEV₁) of 50–85% predicted. Subjects (n = 700) were randomised to receive once-daily (QD) oral GSK2190915 (10–300 mg), twice-daily inhaled fluticasone propionate 100 μg, oral montelukast 10 mg QD or placebo. The primary endpoint was mean change from baseline (randomisation) in trough (morning pre-dose and pre-rescue bronchodilator) FEV₁ at the end of the 8-week treatment period. Secondary endpoints included morning and evening peak expiratory flow, symptom-free days and nights, rescue-free days and nights, day and night-time symptom scores, day and night-time rescue medication use, withdrawals due to lack of efficacy, Asthma Control Questionnaire and Asthma Quality of Life Questionnaire scores.

Results

For the primary endpoint, there was no statistically significant difference between any dose of GSK2190915 QD and placebo. However, repeated measures sensitivity analysis demonstrated nominal statistical significance for GSK2190915 30 mg QD compared with placebo (mean difference: 0.115 L [95% confidence interval: 0.00, 0.23], p = 0.044); no nominally statistically significant differences were observed with any of the other doses. For the secondary endpoints, decreases were observed in day-time symptom scores and day-time SABA use for GSK2190915 30 mg QD versus placebo (p ≤ 0.05). No dose–response relationship was observed for the primary and secondary endpoints across the GSK2190915 dose range studied; the 10 mg dose appeared to be sub-optimal. GSK2190915 was associated with a dose-dependent reduction in urinary leukotriene E₄. The profile and incidence of adverse events were similar between treatment groups.

Conclusion

Efficacy was demonstrated for GSK2190915 30 mg compared with placebo in day-time symptom scores and day-time SABA use. No additional improvement on efficacy endpoints was gained by administration of GSK2190915 doses greater than 30 mg. GSK2190915 was well-tolerated. These results may support further studies with GSK2190915 30 mg.

Trial registration

Clinicaltrials.gov: NCT01147744.

Cysteinyl leukotriene 1 receptor expression associated with bronchial inflammation in severe exacerbations of COPD

BACKGROUND

Cysteinyl leukotriene 1 (CysLT1) receptor expression is known to be increased in the airway mucosa of patients with asthma, especially during exacerbations; however, nothing is known of its expression in COPD.

METHODS

We applied immunohistochemistry and in situ hybridization to endobronchial biopsies to determine inflammatory cell CysLT1 receptor protein and mRNA expression in the following: (1) 15 nonsmoker control subjects (NSC), (2) 16 smokers with moderate to severe COPD in its stable phase (S-COPD), and (3) 15 smokers with COPD hospitalized for a severe exacerbation (SE-COPD).

RESULTS

The total number of bronchial mucosal inflammatory cells (CD45+) and those expressing CysLT1 receptor protein were significantly greater in SE-COPD (CysLT1 receptor protein: median [range] = 139 [31-634]) as compared with S-COPD (32 [6-114]) or NSC (16 [4-66]) (P < .001 for both). CysLT1 receptor gene expression showed similar differences. A greater proportion of CD451 cells expressed CysLT1 receptor protein in SE-COPD (median [range] = 22% [8-81]) compared with S-COPD (10% [4-32]) (P < .03) or NSC (7% [1-19]) (P < .002). In SE-COPD, the relative frequencies of CysLT1 receptor-expressing cells were as follows: tryptase1 mast cells > CD681 monocytes/macrophage > neutrophils > CD201 B lymphocytes = EG21 eosinophils. Moreover, there were positive correlations between the numbers of cells expressing CysLT1 receptor protein and the numbers of CD451 cells (r = 0.78; P < .003) and tryptase1 mast cells (r = 0.62; P < .02).

CONCLUSIONS

Bronchial mucosal CysLT1 receptor-positive inflammatory cells are present in the bronchial mucosa in COPD in greatest number in those experiencing a severe exacerbation.

Leukotriene B4 receptor locus gene characterisation and association studies in asthma

BACKGROUND

Polymorphisms spanning genes involved in the production of leukotriene B4 (LTB4) e.g. ALOX5AP and LTA4H are associated with asthma susceptibility, suggesting a role for LTB4 in disease. The contribution of LTB4receptor polymorphism is currently unknown. The aim of this study was to characterise the genes for the two pivotal LTB4 receptors, LTB4R1 and LTB4R2 in lung tissue and determine if polymorphisms spanning these genes are associated with asthma and disease severity.

METHODS

Rapid amplification of cDNA ends (RACE) was used to characterise the LTB4R1 and LTB4R2 gene structure in lung. The LTB4R1/2 locus on chromosome 14q11.2 was screened for polymorphic variation. Six LTB4R single nucleotide polymorphisms (SNPs) were genotyped in 370 Caucasian asthma families and 299 Adult Asthma Individuals (n=1877 total) and were evaluated for association with asthma and severity (BTS) outcome measures using Family Based Association Test, linear regression and chi square.

RESULTS

LTB4R1 has complex mRNA arrangement including multiple 5'-untranslated exons, suggesting additional levels of regulation. Three potential promoter regions across the LTB4R1/2 locus were identified with some airway cell specificity. 22 SNPs (MAF>0.01) were validated across the LTB4R locus in the Caucasian population. LTB4R1 and LTB4R2 SNPs were not associated with asthma susceptibility, FEV1 or severity.

CONCLUSIONS

LTB4R1 and LTB4R2 shows splice variation in the 5'-untranslated region and multiple promoter regions. The functional significance of this is yet to be determined. Both receptor genes were shown to be polymorphic. LTB4R polymorphisms do not appear to be susceptibility markers for the development of asthma in Caucasian subjects.

Transforming growth factor β1-induced astrocyte migration is mediated in part by activating 5-lipoxygenase and cysteinyl leukotriene receptor 1

BACKGROUND

Transforming growth factor-β 1 (TGF-β 1) is an important regulator of cell migration and plays a role in the scarring response in injured brain. It is also reported that 5-lipoxygenase (5-LOX) and its products, cysteinyl leukotrienes (CysLTs, namely LTC₄, LTD₄ and LTE₄), as well as cysteinyl leukotriene receptor 1 (CysLT₁R) are closely associated with astrocyte proliferation and glial scar formation after brain injury. However, how these molecules act on astrocyte migration, an initial step of the scarring response, is unknown. To clarify this, we determined the roles of 5-LOX and CysLT₁R in TGF-β 1-induced astrocyte migration.

METHODS

In primary cultures of rat astrocytes, the effects of TGF-β 1 and CysLT receptor agonists on migration and proliferation were assayed, and the expression of 5-LOX, CysLT receptors and TGF-β1 was detected. 5-LOX activation was analyzed by measuring its products (CysLTs) and applying its inhibitor. The role of CysLT₁R was investigated by applying CysLT receptor antagonists and CysLT₁R knockdown by small interfering RNA (siRNA). TGF-β 1 release was assayed as well.

RESULTS

TGF-β 1-induced astrocyte migration was potentiated by LTD₄, but attenuated by the 5-LOX inhibitor zileuton and the CysLT₁R antagonist montelukast. The non-selective agonist LTD₄ at 0.1 to 10 nM also induced a mild migration; however, the selective agonist N-methyl-LTC₄ and the selective antagonist Bay cysLT2 for CysLT₂R had no effects. Moreover, CysLT₁R siRNA inhibited TGF-β 1- and LTD₄-induced astrocyte migration by down-regulating the expression of this receptor. However, TGF-β 1 and LTD4 at various concentrations did not affect astrocyte proliferation 24 h after exposure. On the other hand, TGF-β 1 increased 5-LOX expression and the production of CysLTs, and up-regulated CysLT1R (not CysLT₂R), while LTD4 and N-methyl-LTC4 did not affect TGF-β 1 expression and release.

CONCLUSIONS

TGF-β 1-induced astrocyte migration is, at least in part, mediated by enhanced endogenous CysLTs through activating CysLT₁R. These findings indicate that the interaction between the cytokine TGF-β 1 and the pro-inflammatory mediators CysLTs in the regulation of astrocyte function is relevant to glial scar formation.

Ethanol extracts of Saururus chinensis suppress ovalbumin-sensitization airway inflammation

AIM OF THE STUDY

The aerial part of Saururus chinensis has been used in folk medicine to treat several inflammatory diseases in China and Korea. Previously, our group reported that anti-asthmatic activity of an ethanol extract of Saururus chinensis (ESC) might occur, in part, via the inhibition of prostaglandin D(2) (PGD(2)) and leukotriene C(4) (LTC(4)) production, and degranulation reaction in vitro, as well as through the down-regulation of interleukin (IL)-4 and eotaxin mRNA expression in an in vivo ovalbumin-sensitization animal model. However, the effects of Saururus chinensis on eicosanoid generation, as well as Th2 cytokines and eotaxin production in an in vivo asthma model, have not been fully investigated. Moreover, it has not been determined whether ESC can ameliorate airway inflammation in vivo. In the present study, we investigated the therapeutic activity of Saururus chinensis on ovalbumin (OVA)-sensitized airway inflammation and its major phytochemical compositions.

MATERIALS AND METHODS

Asthma was induced in BALB/c mice by ovalbumin-sensitization and inhalation. ESC (10-100 mg/kg) or dexamethasone (5 mg/kg), a positive control, was administered 7 times orally every 12 h from one day before the first challenge to 1 h before the second challenge. The recruitment of inflammatory cells and hyperplasia of goblet cells were evaluated by H&E and PAS staining. Levels of Th2 cytokines, eotaxin, PGD(2) and LTC(4) were measured to evaluate the anti-inflammatory activity of ESC in OVA-sensitized mice. Contents of major components were analyzed by HPLC using a reversed-phase C18 column.

RESULTS

ESC (10 mg/kg) suppressed allergic airway inflammation by inhibition of the production of IL-4 (P<0.001), IL-5 (P<0.05), IL-13 (P<0.001), eotaxin (P<0.001), PGE(2) (P<0.001), LTC(4) (P<0.001) in lung extract and IgE level (P<0.001) in the serum. In addition, ESC (50 mg/kg) reduced the infiltration of inflammatory cells and hyperplasia of goblet cells in the lung tissues. The anti-inflammatory effect of ESC was comparable to that of the positive control drug, dexamethasone. Its major phytochemical composition includes manassantin A, B and sauchinone.

CONCLUSIONS

These results suggest that ESC decreased inflammation and mucus secretion in the OVA-induced bronchial asthma model, and its anti-asthmatic activity may occur in part via the inhibition of Th2 cytokines and eotaxin protein expression, as well as through prostaglandin E(2) (PGE(2)) and leukotriene C(4) (LTC(4)) generation. This effects may be attributed particularly to the presence of manassantin A, B and sauchinone major component evidenced by a HPLC analysis.

Interplay of cysteinyl leukotrienes and TGF-β in the activation of hepatic stellate cells from Schistosoma mansoni granulomas

Hepatic stellate cells (HSCs) have a critical role in liver physiology, and in the pathogenesis of liver inflammation and fibrosis. Here, we investigated the interplay between leukotrienes (LT) and TGF-β in the activation mechanisms of HSCs from schistosomal granulomas (GR-HSCs). First, we demonstrated that GR-HSCs express 5-lipoxygenase (5-LO), as detected by immunolocalization in whole cells and confirmed in cell lysates through western blotting and by mRNA expression through RT-PCR. Moreover, mRNA expression of 5-LO activating protein (FLAP) and LTC(4)-synthase was also documented, indicating that GR-HSCs have the molecular machinery required for LT synthesis. Morphological analysis of osmium and Oil-Red O-stained HSC revealed large numbers of small lipid droplets (also known as lipid bodies). We observed co-localization of lipid droplet protein marker (ADRP) and 5-LO by immunofluorescence microscopy. We demonstrated that GR-HSCs were able to spontaneously release cysteinyl-LTs (CysLTs), but not LTB(4,) into culture supernatants. CysLT production was highly enhanced after TGF-β-stimulation. Moreover, the 5-LO inhibitor zileuton and 5-LO gene deletion were able to inhibit the TGF-β-stimulated proliferation of GR-HSCs, suggesting a role for LTs in HSC activation. Here, we extend the immunoregulatory function of HSC by demonstrating that HSC from liver granulomas of schistosome-infected mouse are able to release Cys-LTs in a TGF-β-regulated manner, potentially impacting pathogenesis and liver fibrosis in schistosomiasis.

Effect of inhaled KP-496, a novel dual antagonist of the cysteinyl leukotriene and thromboxane A2 receptors, on a bleomycin-induced pulmonary fibrosis model in mice

Cysteinyl-leukotrienes (cysLTs) and thromboxane A(2) (TXA(2)) are important mediators in inflammatory lung diseases such as bronchial asthma and idiopathic pulmonary fibrosis (IPF). We examined the effects of inhaled KP-496, a novel dual antagonist of the cysLTs and TXA(2) receptors, on bleomycin-induced IPF in mice. Mice were intravenously injected bleomycin on day 0, and 0.5% of KP-496 was inhaled twice a day (30 min/time) for the entire experimental period. The effects of KP-496 were evaluated by the number of infiltrated cells in bronchoalveolar lavage fluid (BALF), hydroxyl-L-proline content in the lung, and histopathology. Analyses of BALF on days 7 and 21 revealed that inhaled KP-496 significantly decreased total cell numbers, macrophages, neutrophils, and eosinophils on both days. KP-496 significantly decreased hydroxyl-L-proline content in the lung on day 21. Histopathological analyses of lungs on day 21 demonstrated that KP-496 significantly suppressed inflammatory and fibrotic changes. Our results suggested that the suppression of cysLTs and TXA(2) pathways by KP-496 could control airway inflammation and pulmonary fibrosis, and that KP-496 could be a new therapeutic agent for lung diseases with inflammation and fibrogenesis such as IPF and chronic obstructive pulmonary disease.

Natural anti-inflammatory products and leukotriene inhibitors as complementary therapy for bronchial asthma

OBJECTIVE

To assess the efficacy of a combination of Boswellia serrata, licorice root (Glycyrrhiza glabra) and Tumeric root (Curcuma longa) as natural leukotriene inhibitor, antiinflammatory and antioxidant products respectively in controlling bronchial asthma.

SUBJECTS AND METHODS

The study comprised 63 patients with bronchial asthma that are further subdivided into two groups .Group 1 receiving oral capsule (combined herb) in a soft-gelatin capsule 3 times daily for 4weeks and group 2 receiving placebo. Plasma leukotriene C(4) (LTC(4))(,) nitric oxide (NO) and malondialdehyde (MDA) levels were measured and pulmonary function was also assessed in all patients enrolled in the study.

RESULTS

There was a statistically significant decrease in the plasma levels of LTC(4), (MDA), and NO in target therapy group when compared with placebo group.

CONCLUSION

The used extract contained Boswellia serrata, Curcuma longa and Glycyrrhiza has a pronounced effect in the management of bronchial asthma.

Increased parasympathetic tone as the underlying cause of asthma: a hypothesis

Asthma is a chronic inflammatory disease of airways that is characterized by increased responsiveness of the tracheo-bronchial tree to multiple number of stimuli. Immunological theory does not explain all features in asthma, for example hyper-reactivity of the airways. Neurogenic theory also fails to explain the pathogenesis of asthma comprehensively. Higher parasympathetic tone has been reported in asthmatics but has never been suggested as a major underlying cause of asthma. This article attempts to explain the occurrence of hyper-responsiveness, inflammatory/allergic reactions and broncho-constriction in asthma on a common basis of inherent higher parasympathetic tone in asthmatics. The higher background parasympathetic firing leads to increased nitric oxide (NO) production owing to its co-localization with acetylcholine (ACh) in inhibitory non-adrenergic and non-cholinergic (i-NANC) nerves. NO is a neurotransmitter of i-NANC system and it mediates bronchodilation. Increased NO release has been found to be responsible for hyper-responsiveness and increased inflammation in the airways. The authors suggest that an inherently higher background parasympathetic tone in concert with inflammation or a specific genetic background could modify the effects of NO on lung homeostasis in humans leading to increased susceptibility to an asthmatic state.

Clinical study of the effects on asthma-related QOL and asthma management of a medical food in adult asthma patients

BACKGROUND

Asthma can have a negative impact on quality of life although this is not well correlated with objective evaluations of pulmonary function. A medical food, EFF1009, containing the fatty acids gamma-linolenic acid (GLA) and eicosapentaenoic acid (EPA) decreases leukotriene B(4) synthesis in patients with asthma. Two previous clinical studies with EFF1009 provided preliminary evidence that the medical food improves asthma-related quality of life (ARQOL) and asthma management.

OBJECTIVE

To evaluate the impact on ARQOL of EFF1009 in adults with asthma.

RESEARCH DESIGN AND METHODS

The study was a randomized, prospective, double-blind, placebo-controlled, parallel group study in twenty-one (N = 21 evaluable) subjects with mild to moderate persistent asthma who consumed the medical food emulsion or placebo emulsion daily for 28 days. All participants continued their asthma medications throughout the study. ARQOL, including asthma signs and symptoms, and asthma control were measured using the Mini Asthma Quality of Life Questionnaire (MiniAQLQ) and the Asthma Control Questionnaire (ACQ), administered at baseline, Day 14 and Day 28. Safety and tolerability parameters, including adverse events, were monitored.

RESULTS

Baseline ARQOL scores, forced expiratory volume in one second (FEV(1)) and other characteristics were balanced between both groups. Mean (standard error) total MiniAQLQ scores changed by 0.73 (0.38) and -0.22 (0.36) in the EFF1009 and placebo groups, respectively, (p < 0.05). The MiniAQLQ symptom domain score was improved in the EFF1009 group (p < 0.05). Total scores for the ACQ were not significantly improved in either group. Levels of the fatty acid EPA in plasma increased in the EFF1009 group but not the placebo group (p < 0.03). The medical food was well tolerated and no safety concerns were identified.

CONCLUSIONS

The dietary addition of the medical food EFF1009 to asthma management regimens can improve patient perceived, ARQOL and can also improve asthma management as evidenced by reduced asthma symptoms. An additional study of the medical food, with larger subject population and longer treatment duration, is warranted to confirm these findings.

Leukotriene pathway genetics and pharmacogenetics in allergy

Leukotrienes (LT) are biologically active lipid mediators known to be involved in allergic inflammation. Leukotrienes have been shown to mediate diverse features of allergic conditions including inflammatory cell chemotaxis/activation and smooth muscle contraction. Cysteinyl leukotrienes (LTC(4), LTD(4) and, LTE(4)) and the dihydroxy leukotriene LTB(4) are generated by a series of enzymes/proteins constituting the LT synthetic pathway or 5-lipoxygenase (5-LO) pathway. Their function is mediated by interacting with multiple receptors. Leukotriene receptor antagonists (LTRA) and LT synthesis inhibitors (LTSI) have shown clinical efficacy in asthma and more recently in allergic rhinitis. Despite growing knowledge of leukotriene biology, the molecular regulation of these inflammatory mediators remains to be fully understood. Genes encoding enzymes of the 5-LO pathway (i.e. ALOX5, LTC4S and LTA4H) and encoding for LT receptors (CYSLTR1/2 and LTB4R1/2) provide excellent candidates for disease susceptibility and severity; however, their role remains unclear. Preliminary data also suggest that 5-LO pathway/receptor gene polymorphism can predict patient responses to LTSI and LTRA; however, the exact mechanisms require elucidation. The aim of this review was to summarize the recent advances in the knowledge of these important mediators, focusing on genetic and pharmacogenetic aspects in the context of allergic phenotypes.

Allergic rhinitis in patients with asthma: the Swiss LARA (Link Allergic Rhinitis in Asthma) survey

OBJECTIVE

To determine the characteristics of asthma (A) and allergic rhinitis (AR) among asthma patients in primary care practice.

RESEARCH DESIGN AND METHODS

Primary care physicians, pulmonologists, and allergologists were asked to recruit consecutive asthma patients with or without allergic rhinitis from their daily practice. Cross-sectional data on symptoms, severity, treatment and impact on quality of life of A and AR were recorded and examined using descriptive statistics. Patients with and without AR were then compared.

RESULTS

1244 asthma patients were included by 211 physicians. Asthma was controlled in 19%, partially controlled in 27% and not controlled in 54%. Asthma treatment was generally based on inhaled corticosteroids (ICS) with or without long acting beta 2 agonists (78%). A leukotriene receptor antagonist (LTRA) was used by 46% of the patients. Overall, 950 (76%) asthma patients had AR (A + AR) and 294 (24%) did not (A - AR). Compared to patients with A - AR, A + AR patients were generally younger (mean age +/- standard deviation: 42 +/- 16 vs. 50 +/- 19 years, p < 0.001) and fewer used ICS (75% vs. 88%, p < 0.001). LTRA usage was similar in both groups (46% vs. 48%). Asthma was uncontrolled in 53% of A + AR and 57% of A - AR patients. Allergic rhinitis was treated with a mean of 1.9 specific AR medications: antihistamines (77%), nasal steroids (66%) and/or vasoconstrictors (38%), and/or LTRA (42%). Rhinorrhoea, nasal obstruction, or nasal itching were the most frequently reported AR symptoms and the greatest reported degree of impairment was in daily activities/sports (55%).

CONCLUSIONS

Allergic rhinitis was more common among younger asthma patients, increased the burden of symptoms and the need for additional medication but was associated with improved asthma control. However, most asthma patients remained suboptimally controlled regardl-ess of concomitant AR.

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.

4-thiouridine induces dose-dependent reduction of oedema, leucocyte influx and tumour necrosis factor in lung inflammation

Recent reports demonstrate a role for nucleotides as inflammatory modulators. Uridine, for example, reduces oedema formation and leucocyte infiltration in a Sephadex-induced lung inflammation model. Tumour necrosis factor (TNF) concentration was also reduced. Previous in vivo observations indicated that 4-thiouridine might have similar effects on leucocyte infiltration and TNF release. The aim of this study was thus to investigate the effects of 4-thiouridine in greater detail. We used a Sephadex-induced acute lung inflammation model in Sprague-Dawley rats. The dextran beads were instilled intratracheally into the lungs, which were excised and examined after 24 h. Sephadex alone led to massive oedema formation and infiltration of macrophages, neutrophils and eosinophils. Microgranulomas with giant cell formations were clearly visible around the partially degraded beads. A significant increase in bronchoalveolar lavage fluid (BALF) content of TNF and leukotrienes was also seen. 4-Thiouridine co-administration affected all variables investigated in this model, i.e. oedema, microscopic and macroscopic appearance of lung tissue, total leucocyte and differential leucocyte counts in BALF, TNF and leukotrienes C(4) (LTC(4)), LTD(4 )and LTE(4) in BALF, indicating a reproducible anti-inflammatory effect. In conclusion, we have demonstrated that 4-thiouridine has anti-inflammatory effects similar to those of uridine. To our knowledge, this is the first demonstration of pharmacological 4-thiouridine effects in vivo. The results suggest nucleoside/nucleotide involvement in inflammatory processes, warranting further studies on nucleoside analogues as attractive new alternatives in the treatment of inflammatory diseases.

Urine concentrations of cysteinyl leukotrienes in children with obstructive sleep-disordered breathing

BACKGROUND

Adenotonsillar tissue of children with obstructive sleep-disordered breathing (SDB) has increased content of cysteinyl leukotrienes (CysLTs) and expression of CysLTs receptors. Furthermore, CysLTs concentrations in the nasal exhaled breath condensate of children with sleep apnea are elevated.

OBJECTIVE

To investigate the relationship between urine levels of CysLTs and severity of SDB in children.

METHODS

Morning urine concentrations of CysLTs were measured in children with symptoms of SDB and in control subjects with recurrent tonsillitis and without snoring who underwent polysomnography and were expressed in pg/mL per mg/dL of urine creatinine.

RESULTS

Nineteen children with moderate-to-severe SDB (mean [+/- SD] age, 5.4 +/- 1.6 years; obstructive apnea-hypopnea index [OAHI]: 14.4 +/- 9.6 episodes/h), 29 subjects with mild SDB (5.1 +/- 1.5 years; OAHI: 2.9 +/- 0.8 episodes/h), 26 children with primary snoring (PS) [7 +/- 2.6 years; OAHI: 1.1 +/- 0.3 episodes/h], and 18 control subjects (6.4 +/- 2.5 years; OAHI: 0.7 +/- 0.3 episodes/h) were studied. Children with moderate-to severe SDB had higher log-transformed urine CysLTs levels than those with mild SDB, PS, or control subjects (2.39 +/- 0.51 vs 2.06 +/- 0.26 vs 2.11 +/- 0.25 vs 1.86 +/- 0.28; p < 0.05). Log-transformed CysLTs concentration, tonsillar size, and body mass index z score were significant predictors of log-transformed OAHI (p < 0.01).

CONCLUSIONS

Urine excretion of CysLTs is related to SDB severity in children. This finding indicates that 5-lipoxygenase pathway products participate in the pathogenesis of obstructive sleep apnea in childhood or alternatively that SDB promotes CysLTs biosynthesis.

Hyperleukotrieneuria in patients with allergic and inflammatory disease

Cysteinyl leukotrienes (CysLTs: leukotrienes C(4), D(4), and E(4)) have long been implicated in the pathogenesis of asthma and several allergic diseases. LTE(4) has been identified as a major metabolite of LTC(4), and urinary LTE(4) (U-LTE(4)) is considered as the most reliable analytic parameter for monitoring the endogenous synthesis of CysLTs. From recent studies on the U-LTE(4) associated with adult stable asthma we identified four factors for hyperleukotrieneuria, namely, aspirin intolerance, eosinophilic nasal polyposis (ENP), vasculitis, and severe asthma. In ENP, there is prominent infiltration of eosinophils in the sinus and polyp tissues, which is linked to adult asthma and aspirin sensitivity, and ENP is the most important factor for the overproduction of CysLTs in asthmatics. We also demonstrated that anaphylaxis and eosinophilic pneumonia (EP) are associated with a marked increase in the U-LTE(4) concentration. Under these disease conditions, U-LTE(4) may be one of the candidate biomarkers. Moreover, the changes in U-LTE(4) concentrations may provide valuable information concerning therapeutic targets.

Exhaled breath condensate in patients with asthma: implications for application in clinical practice

Exhaled breath condensate (EBC) analysis, a rather appealing and promising method, can be used to evaluate conveniently and non-invasively a wide range of molecules from the respiratory tract, and to understand better the pathways propagating airway inflammation. A large number of mediators of inflammation, including adenosine, ammonia, hydrogen peroxide, isoprostanes, leukotrienes, prostanoids, nitrogen oxides, peptides and cytokines, have been studied in EBC. Concentrations of such mediators have been shown to be related to the underlying asthma and its severity and to be modulated by therapeutic interventions. Despite the encouraging positive results to date, the introduction of EBC in everyday clinical practice requires the resolution of some methodological pitfalls, the standardization of EBC collection and finally the identification of a reliable biomarker that is reproducible has normal values and provides information regarding the underlying inflammatory process and the response to treatment. So far, none of the parameters studied in EBC fulfils the aforementioned requirements with one possible exception: pH. EBC pH is reproducible, has normal values, reflects a significant part of asthma pathophysiology and is measurable on-site with standardized methodology although some methodological aspects of measurement of pH in EBC (e.g. the effect of ambient CO(2), sample de-aeration, time for pH measurement) require further research. However, EBC pH has not been evaluated prospectively as a guide for treatment, in a manner similar to exhaled NO and sputum eosinophils. EBC represents a simple and totally non-invasive procedure that may contribute towards our understanding of asthma pathophysiology. Besides the evaluation of new biomarkers, the standardization of the already existing procedures is warranted for the introduction of EBC in clinical practice.

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.

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.

Motorcycle exhaust particles augment antigen-induced airway inflammation in BALB/c mice

Evidence indicates that environment pollutants from fossil fuel combustion compromise the immune system by enhancing allergic reactions and damaging the respiratory tract. This study was performed to investigate the effects of motorcycle exhaust particles (MEP), a major air pollutant especially in the urban areas of Taiwan, on allergen-induced airway inflammatory reactions in lab animals. BALB/c mice were intratracheally instilled with ovalbumin (OVA), MEP, or phosphate-buffered saline, 3 times every 2 wk. Airway hyperresponsiveness was measured in unrestrained mice by barometric plethsmography. Bronchoalveolar lavage fluid (BALF) and serum from treated animals were collected for cytokine and antibody determination by enzyme-linked immunosorbent assay (ELISA). Lung tissue stained with hematoxylin/eosin was examined. Data showed that MEP augmented OVA-induced airway inflammation; characterized by infiltration of eosinophils and neutrophils in BALF and lung tissue inflammation. The combination of OVA and MEP markedly increased interleukin-4 (IL-4), interleukin-5 (IL-5), and tumor necrosis factor-alpha (TNF-alpha) protein levels in BALF. In addition, MEP also augmented OVA-induced rise in OVA-specific immunoglobulin (Ig) G1 and IgE and airway hyperresponsiveness. Pretreated lavage cells with mitogen-activated protein kinase (MAPK) inhibitors showed that TNF-alpha release was significantly inhibited. This study found that MEP augmented antigen-induced allergic airway inflammation and airway hyperresponsiveness through a Th2-dominant pathway.

Antileukotrienes as adjunctive therapy in acute asthma

The leukotriene receptor antagonists (LTRAs) are a comparatively new class of asthma drugs that exhibit both bronchodilator and anti-inflammatory properties. There is a substantial body of evidence for their benefit in the management of chronic asthma in both adults and children, and particularly in specific types of asthma such as exercise-induced and aspirin-sensitive asthma. Despite best practice using current treatment guidelines for the management of acute asthma, a significant proportion of patients require continued treatment and are unable to be discharged from the emergency department; many require a short course of oral corticosteroids. The relatively rapid onset of action of LTRAs after oral administration and their additive effect to beta(2)-adrenoceptor agonists led to the hypothesis that they might be of benefit in acute asthma. This review examines the available evidence for the effect of LTRAs in acute asthma. Although the evidence is limited, it suggests that treatment with LTRAs provides additional bronchodilator effect to nebulised and inhaled beta(2)-adrenoceptor agonists. Short-term therapy with LTRAs results in fewer treatment failures and readmissions for patients with acute asthma, and less need for additional therapies such as nebulisers and corticosteroids.

Synthesis and biological activities of a series of 4,5-diaryl-3-hydroxy-2(5H)-furanones

A series of thirteen 4,5-diaryl-3-hydroxy-2(5H)-furanones were synthesized. They were evaluated for their antioxidant potencies and inhibitory properties of 5-lipoxygenase, cyclooxygenases, HIV-1 integrase and PC3 cell proliferation. New hits were discovered either in the anti-proliferation test or in the HIV anti-integrase test.

Treatment heterogeneity in asthma: genetics of response to leukotriene modifiers

Despite advances in treatment, asthma continues to be a significant health and economic burden. Although asthma cannot be cured, several drugs, including beta2 agonists, corticosteroids, and leukotriene (LT) modifiers, are well tolerated and effective in minimizing symptoms, improving lung function, and preventing exacerbations. However, inter-patient variability in response to asthma drugs limits their effectiveness. It has been estimated that 60-80% of this inter-patient variability may be attributable to genetic variation. LT modifiers, in particular, have been associated with heterogeneity in response. These drugs exert their action by inhibiting the activity of cysteinyl leukotrienes (CysLTs), which are potent bronchoconstrictors and pro-inflammatory agents. Two classes of LT modifiers are 5-lipoxygenase (ALOX5) inhibitors (zileuton) and leukotriene receptor antagonists (LTRAs) [montelukast, pranlukast, and zarfirlukast]. LT modifiers can be used as alternatives to low-dose inhaled corticosteroids (ICS) in mild persistent asthma, as add-on therapy to low- to medium-dose ICS in moderate persistent asthma, and as add-on to high-dose ICS and a long-acting ss2 agonist in severe persistent asthma. At least six genes encode key proteins in the LT pathway: arachidonate 5-lipoxygenase (ALOX5), ALOX5 activating protein (ALOX5AP [FLAP]), leukotriene A4 hydrolase (LTA4H), LTC4 synthase (LTC4S), the ATP-binding cassette family member ABCC1 (multidrug resistance protein 1 [MRP1]), and cysteinyl leukotriene receptor 1 (CYSLTR1). Studies have reported that genetic variation in ALOX5, LTA4H, LTC4S, and ABCC1 influences response to LT modifiers. Plasma concentrations of LTRAs vary considerably among patients. Physio-chemical characteristics make it likely that membrane efflux and uptake transporters mediate the absorption of LTRAs into the systemic circulation following oral administration. Genes that encode efflux and uptake transport proteins harbor many variants that could influence the pharmacokinetics, and particularly the bioavailability, of LTRAs, and could contribute to heterogeneity in response. In the future, large, well designed clinical trials studying the pharmacogenetics of LT modifiers in diverse populations are warranted to determine whether a genetic signature can be developed that will accurately predict which patients will respond.

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.

Inflammation and disease progression

Inflammation is a physiological response to a foreign organism such as bacteria, dust particles, and viruses. Recent studies have enlightened the role of inflammation in the progression of a variety of diseases such as cancer, atherosclerosis, asthma, and psoriasis. This article is a brief overview of the inflammatory processes involved in the progression of these common diseases. Knowledge about these mechanisms can shed light into development of newer therapeutic agents that are aimed at the eradication of these diseases.

Pharmacotherapy of diseases mediated by 5-lipoxygenase pathway eicosanoids

Inflammatory eicosanoids generated by the 5-lipoxygenase (5-LO) pathway of arachidonic acid metabolism are now known to have at least 6 receptors: OXE, which recognizes 5-HETE and 5-oxo-ETE; a putative receptor recognizing a potent 5-oxo-ETE metabolite, FOG(7); the LTB(4) receptors, BLT1 and BLT2; the cysteinyl leukotriene receptors, CysLT(1) and CysLT(2), which recognize leukotrienes LTC(4), LTD(4), LTE(4) and LTF(4). The 5-LO pathway is activated in many diseases and invokes inflammatory responses not affected by glucocorticoids, but therapy with selective BLT1 or CysLT(1) antagonists in asthma has met with variable success. Studies show that 5-LO pathway eicosanoids are not primary mediators in all cases of asthma, but may be especially important in severe persistent asthma, aspirin- and exercise-induced asthma, allergic rhinitis, COPD, idiopathic pulmonary fibrosis, atherosclerosis, atopic dermatitis, acne and ischemia-related organ injury. These disorders appear to involve multiple 5-LO pathway eicosanoids and receptor subtypes, suggesting that inhibition of the pathway at the level of 5-LO may be necessary for maximal efficacy.

Combined mediator blockade or topical steroid for treating the unified allergic airway

BACKGROUND

Asthma and allergic rhinitis are manifestations of a single unified allergic airway, for which the best treatment is uncertain.

OBJECTIVE

To compare the anti-inflammatory efficacy in the unified allergic airway of combined oral mediator antagonism and combined topical steroid.

METHODS

Subjects with asthma and perennial allergic rhinitis entered a randomized double blind crossover study comparing montelukast 10 mg and cetirizine 10 mg to extra-fine inhaled beclomethasone 400 mcg/day and intranasal beclomethasone 200 mcg/day, each taken once daily for 2 months, after 2-week placebo washouts. Measurements were made after each washout and randomized treatment, comprising: methacholine PC20, exhaled and nasal nitric oxide, blood eosinophils and eosinophilic cationic protein, symptoms, lung and nasal function tests.

RESULTS

Seventeen patients completed per protocol. For PC20 and exhaled nitric oxide, only combined topical steroid produced improvements (P < 0.005) from placebo baseline. Combined steroid was superior by a 0.93 (95% CI 0.14-0.93, P < 0.05) doubling dilution difference for PC20 and a 0.99 (95% CI 0.9-15.1, P < 0.01) doubling difference for exhaled nitric oxide. Both treatments attenuated eosinophils and eosinophilic cationic protein, and reduced nasal symptoms (P < 0.05). Only steroid improved nasal nitric oxide (P=0.05) and asthma symptoms (P < 0.05). Neither treatment affected lung or nasal function tests.

CONCLUSION

Combined topical steroid and combined mediator antagonism both attenuated systemic inflammation in the unified allergic airway, but only the former reduced bronchial and nasal inflammatory markers. The relevance of this to exacerbations and airway remodelling needs to be defined.

Treating asthma as an inflammatory disease

Asthma is a chronic inflammatory disease involving many different cell types and cellular elements. Evidence suggests that, in the long term, this inflammation leads to remodeling of the airways, airflow obstruction, and the bronchial hyperreactivity symptoms of asthma, and is present even in patients with intermittent disease. Patients with allergic asthma and those with seasonal allergic rhinitis are believed to have minimal persistent inflammation, and the two diseases often occur together. Early intervention with inhaled corticosteroids (ICS) is believed to modify the disease process and may limit long-term remodeling. ICS remain the cornerstone and "gold standard" of treatment for asthma.