Leukotriene Research Articles

Controller therapy attenuates asthma exacerbations associated with prior severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) infection in children

Controller therapy attenuates asthma exacerbations associated with prior severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) infection in children

Integrated Single-Cell and Transcriptome Sequencing Analyses Identify Dipeptidase 2 as an Immune-Associated Prognostic Biomarker for Lung Adenocarcinoma.

Dipeptidase 2 (DPEP2) is a dipeptidyl peptidase that plays an important role in the hydrolysis of leukotriene D4 (LTD4) to leukotriene E4 (LTE4). Previous studies have suggested that LTD4 promotes tumor progression and survival in non-small cell lung cancer (NSCLC). Therefore, we hypothesized that DPEP2 may play a pivotal role in this tumor. Given that lung adenocarcinoma (LUAD) is the most common subtype of NSCLC, our study aimed to examine the expression and function of DPEP2 in LUAD. Based on bioinformatics and the analysis of clinical samples, our findings revealed that DPEP2 is highly expressed in normal lung tissues, but downregulated in LUAD tissues, and its expression levels were significantly associated with clinical indicators of tumor grade and prognosis. Pathway enrichment analysis showed that DPEP2 is involved in biological processes such as chemokine signaling pathways, leukocyte trans-endothelial migration, and humoral immune responses in LUAD. In addition, DPEP2 expression was significantly associated with various immune cells, especially monocytes-macrophages. Single-cell transcriptome data further confirmed the expression of DPEP2 dominantly in macrophages from normal lung tissues. Analysis of the TCIA database revealed that high DPEP2 expression is associated with a stronger response to immune checkpoint inhibitors such as CTLA4 and PD1, and determines sensitivity to LUAD therapeutic agents. Furthermore, we found that DPEP2 inhibits the migration and invasion of LUAD cells. Therefore, DPEP2 may serve as a potential immune biomarker and therapeutic target for LUAD, providing novel therapeutic approaches for this disease.

Cysteinyl leukotriene-like metabolites are generated in retinal pigment epithelial cells through glutathionylation/reduction of an oxidatively truncated fragment of arachidonate

γ-Hydroxyalkenals, 4-hydroxynonenal (HNE) and phospholipid esters of 4-hydroxy-8-oxooctenoic acid (HOOA-PL), are produced from the alkyl and carboxyl termini of arachidonyl phospholipids by radical-induced oxidative cleavage. Metabolism of HNE by Michael addition of glutathione (GSH) followed by reduction of the aldehyde carbonyl produces a GSH derivative of 1,4-dihydroxynonane (DHN)-GSH. Analogous biochemistry was anticipated to produce a GSH derivative of 5,8-dihydroxyoctanoic acid (DHOA-GSH) that has structural and functional similarity to the cysteinyl leukotriene (LT)C4. We now report that exposure of human retinal pigment epithelial cells to CoCl2, an in vitro model of hypoxia-induced oxidative stress, generates DHOA-GSH and two products of its peptidolysis, DHOA-CysGly and DHOA-Cys that resemble LTD4 and LTE4. Identification of these metabolites was confirmed by unambiguous chemical syntheses that also provided a heavy isotope labeled quantitative standard 13C215N-DHOA-GSH. The availability of pure samples of these arachidonate metabolites will enable assessment of their biological activities, and testing the hypothesis that øLTs promote pathological inflammation by serving as LT receptor agonists. Because LT biosynthetic enzymes, e.g., 5-lipoxygenase, are not involved in the generation of øLTs in vivo, inhibitors of LT biosynthesis, e.g., Zileuton, are not expected to prevent the generation of øLTs. On the other hand, if øLTs are leukotriene receptor agonists, then the therapeutic effects of leukotriene receptor antagonist drugs, e.g., Montelukast, may include inhibition not only of LT-induced but also øLT-induced LT receptor activation and signaling.

Neutrophil extracellular trap production and CCL4L2 expression influence corticosteroid response in asthma.

The association between neutrophil extracellular traps (NETs) and response to inhaled corticosteroids (ICS) in asthma is unclear. To better understand this relationship, we analyzed the blood transcriptomes from children with controlled and uncontrolled asthma in the Taiwanese Consortium of Childhood Asthma Study using weighted gene coexpression network analysis and pathway enrichment methods. We identified 298 uncontrolled asthma-specific differentially expressed genes and one gene module associated with neutrophil-mediated immunity, highlighting a potential role for neutrophils in uncontrolled asthma. We also found that NET abundance was associated with nonresponse to ICS in patients. In a neutrophilic airway inflammation murine model, steroid treatment could not suppress neutrophilic inflammation and airway hyperreactivity. However, NET disruption with deoxyribonuclease I (DNase I) efficiently inhibited airway hyperreactivity and inflammation. Using neutrophil-specific transcriptomic profiles, we found that CCL4L2 was associated with ICS nonresponse in asthma, which was validated in human and murine lung tissue. CCL4L2 expression was also negatively correlated with pulmonary function change after ICS treatment. In summary, steroids fail to suppress neutrophilic airway inflammation, highlighting the potential need to use alternative therapies such as leukotriene receptor antagonists or DNase I that target the neutrophil-associated phenotype. Furthermore, these results highlight CCL4L2 as a potential therapeutic target for individuals with asthma refractory to ICS.

Involvement of p38 MAPK/cPLA2 and arachidonic acid metabolic pathway in Shengmai injection-induced pseudo-allergic reactions.

Adverse reactions to traditional Chinese medicine injections involve pseudo-allergic reactions (PARs). However, in clinical practice, "immediate allergic reactions" and PARs in response to these injections are not often differentiated. This study aimed to clarify the type of reactions produced by Shengmai injections (SMI) and elucidate the possible mechanism. A mouse model was used to evaluate vascular permeability. Metabolomic and arachidonic acid metabolite (AAM) analyses were performed using UPLC-MS/MS, and the p38 MAPK/cPLA2 pathway was detected by western blotting. The first exposure to intravenous SMI rapidly and dose-dependently induced edema and exudative reactions in the ears and lungs. These reactions were not IgE-dependent and were likely to be PARs. Metabolomic analysis showed that endogenous substances were perturbed in SMI-treated mice, in which the arachidonic acid (AA) metabolic pathway was the most affected. SMI substantially increased the levels of AAMs in lung, including prostaglandins (PGs), leukotrienes (LTs), and hydroxy-eicosatetraenoic acids (HETEs). The p38 MAPK/cPLA2 signaling pathway was activated after a single SMI dose. Inhibitors of cyclooxygenase-2 and 5-lipoxygenase enzymes reduced exudation and inflammation in the ears and lungs of mice. Production of inflammatory factors that increase vascular permeability may result in SMI-induced PARs, and p38 MAPK/cPLA2 signaling pathway and downstream AA metabolic pathway are involved in the reactions.

Suppression of epithelial-mesenchymal transition and SIRT1/AKT signaling pathway in breast cancer by montelukast

Breast cancer is usually associated with metastatic features, poor prognosis, and high mortality. The epithelial-mesenchymal transition (EMT) process has been implicated in the initiation and metastasis of breast cancer. The study aimed to investigate the possible role of montelukast (Mont), the cysteinyl leukotriene receptor (CystLT1R) antagonist, in mitigating EMT in triple-negative breast cancer (TNBC) (in vitro study) and solid Ehrlich carcinoma (SEC) bearing mice (in vivo study) as well as to clarify the underlying molecular mechanisms in the presence and absence of sirtuin-1 inhibitor (sirtinol; Sirt). TNBC MDA-MB-231 cells were treated with either 5μM Mont or 25μM Sirt or both for 48h. Alternatively, SEC cells were inoculated in mice to induce breast cancer. After 12days, the mice were divided into four groups: Untreated SEC group (vehicle), Sirt group (1mg/kg), Mont group (10mg/kg), and cotreatment Sirt/Mont group. The mice groups received the assigned treatment for the consequent 16days. Mont and/or Sirt decreased cell proliferation, migration and suppressed EMT in both in vitro and in vivo experiments. All treatments downregulated sirtuin-1 and vimentin expression but upregulated E-cadherin expression. Furthermore, all treatments retarded angiogenesis as evidenced by decreased VEGF expression. These findings were associated with suppressing active protein kinase B (p-AKT). Cotreatment with Sirt and Mont proved more effective anti-tumor activity in TNBC cell line and in SEC bearing mice than either treatment alone, which could be attributed to the inhibition of sirtuin-1 and AKT- activated pathways, with the subsequent inhibition of EMT.

Distinct eicosanoid patterns in severe recalcitrant nasal polyposis.

Although altered eicosanoid levels are related to disease severity in chronic rhinosinusitis with nasal polyps (CRSwNP), identifying patients prone to recurrent nasal polyps (NPs) is still difficult. We investigated levels of nasally secreted eicosanoids before and after NP surgery in patients with or without NP recurrence (NPR) and explored potential endotypes based on pre-surgical eicosanoid levels. Levels of leukotriene (LT) E4 , LTB4 , prostaglandin (PG) D2 , PGE2 and 15(S) hydroxyeicosatetraenoic acid (15[S]-HETE) were measured in nasal secretions with specific immunoassays at pre-surgery (n=38) and 6 and 12 months post-surgery (n=35), with NPR identified endoscopically. Pre- and post-surgical levels were compared between patients with and without NPR. Eicosanoid patterns among patients were explored with cluster analysis and evaluated with clinical parameters. Patients with recurrent NPs had pronounced pre-surgical levels of nasal 15(S)-HETE, PGD2 and LTE4 . From pre-surgery to 12 months post-surgery, NPR was associated with significant decreases of 15(S)-HETE and PGD2 relative to non-recurrence, whereas levels of LTE4 decreased at 6 months but increased again at 12 months. Clustering revealed three potential endotypes. Clusters 1 and 3 featured high and low eicosanoid levels, respectively. Cluster 2 had higher levels of LTE4 and PGD2 , lower levels of PGE2 and LTB4 , and more cases of recurrent NPs and previous NP surgeries. Elevated nasal LTE4 12 months post-surgery in NP recurrent subjects suggests that postoperative LTE4 measurements may indicate rapid NP regrowth. A distinct nasal eicosanoid profile may be used for the identification of the most severe recalcitrant patients in need of targeted immunomodulatory therapies.

Dual synergistic inhibition of COX and LOX by potential chemicals from Indian daily spices investigated through detailed computational studies

Cyclooxygenase (COX) and Lipoxygenase (LOX) are essential enzymes for arachidonic acid (AA) to eicosanoids conversion. These AA-derived eicosanoids are essential for initiating immunological responses, causing inflammation, and resolving inflammation. Dual COX/5-LOX inhibitors are believed to be promising novel anti-inflammatory agents. They inhibit the synthesis of prostaglandins (PGs) and leukotrienes (LTs), but have no effect on lipoxin formation. This mechanism of combined inhibition circumvents certain limitations for selective COX-2 inhibitors and spares the gastrointestinal mucosa. Natural products, i.e. spice chemicals and herbs, offer an excellent opportunity for drug discovery. They have proven anti-inflammatory properties. However, the potential of a molecule to be a lead/ drug candidate can be much more enhanced if it has the property of inhibition in a dual mechanism. Synergistic activity is always a better option than the molecule's normal biological activity. Herein, we have explored the dual COX/5-LOX inhibition property of the three major potent phytoconsituents (curcumin, capsaicin, and gingerol) from Indian spices using in silico tools and biophysical techniques in a quest to identify their probable inhibitory role as anti-inflammatory agents. Results revealed the dual COX/5-LOX inhibitory potential of curcumin. Gingerol and capsaicin also revealed favorable results as dual COX/5-LOX inhibitors. Our results are substantiated by target similarity studies, molecular docking, molecular dynamics, energy calculations, DFT, and QSAR studies. In experimental inhibitory (in vitro) studies, curcumin exhibited the best dual inhibitory activities against COX-1/2 and 5-LOX enzymes. Capsaicin and gingerol also showed inhibitory potential against both COX and LOX enzymes. In view of the anti-inflammatory potential these spice chemicals, this research could pave the way for more scientific exploration in this area for drug discovery.

Lipid mediators in the regulation of innate and adaptive immunity.

Lipid mediators in the regulation of innate and adaptive immunity.

Effects of Ganoderma lucidum polysaccharide peptide ameliorating cyclophosphamide-induced immune dysfunctions based on metabolomics analysis.

Ganoderma lucidum polysaccharide peptide (GLPP) is one of the most abundant constituents of Ganoderma lucidum (G. lucidum), with a wide range of functional activities. The present study investigated the immunomodulatory effects of GLPP in cyclophosphamide (CTX)-induced immunosuppressive mice. The results showed that 100 mg/kg/day of GLPP administration significantly alleviated CTX-induced immune damage by improving immune organ indexes, earlap swelling rate, the index of carbon phagocytosis and clearance value, secretion of cytokines (TNF-α, IFN-γ, and IL-2), and immunoglobulin A(IgA) in the mice. Furthermore, ultra-performance liquid chromatography with mass/mass spectrometry (UPLC-MS/MS) was conducted to identify the metabolites, followed by biomarker and pathway analysis. The results showed that GLPP treatment alleviated CTX-induced alterations in the fecal metabolome profile, including arachidonic acid (AA), leukotriene D4 (LTD4), indole-3-ethanol, and formyltetrahydrofolate (CF), by reversing citric acid, malic acid, cortisol, and oleic acid. These results support the concept that GLPP exhibits immunomodulatory activity via the folate cycle, methionine cycle, TCA cycle, fatty acid biosynthesis and metabolism, glycerophospholipid metabolism, AA metabolism, and cAMP pathways. In conclusion, the results could be helpful to understand the use of GLPP to clarify the immunomodulatory mechanism and be used as immunostimulants to prevent CTX-induced side effects in the immune system.

Efficacy and safety of montelukast adjuvant therapy in adults with cough variant asthma: A systematic review and meta-analysis.

Montelukast is a highly selective and specific cysteinyl leukotriene receptor antagonist used in the treatment of asthma. Whether montelukast as adjuvant therapy can significantly and safely treat adults with cough variant asthma (CVA) remains inconclusive. This meta-analysis systematically evaluated the efficacy and safety of montelukast as an adjuvant treatment for adults with CVA. Randomized controlled trials (RCTs) on montelukast combined with inhaled corticosteroids (ICS) and long-acting β2 agonists (LABAs) to treat CVA in adults, from inception to March 6, 2023, were retrieved from the CNKI, Wanfang, VIP, CBM, PubMed, Embase, Cochrane Library, and Web of Science databases and Clinical Trials website. Review Manager (version 5.4) and Stata (version 15.0) were used to conduct the meta-analysis. A total of 15 RCTs were ultimately included in the meta-analysis. It was established that montelukast as adjuvant therapy raised the total effective rate (RR = 1.20, 95% confidence interval [CI] [1.13, 1.27], P < 0.01) and improved the FEV1% (SMD = 0.91, 95% CI [0.40, 1.41], P < 0.01), PEF% (SMD = 0.63, 95% CI [0.38, 0.88], P < 0.01), FEV1 (SMD = 1.15, 95% CI [0.53, 1.77], P < 0.01), PEF (SMD = 0.64, 95% CI [0.42, 0.86], P < 0.01), and FEV1/FVC% (SMD = 0.76, 95% CI [0.51, 1.01], P < 0.01) and reduced the recurrence rate (RR = 0.28, 95% CI [0.15, 0.53], P < 0.01). The incidence of adverse reactions was higher in the montelukast auxiliary group compared to the control group but with no statistical difference (RR = 1.32, 95% CI [0.89, 1.96], P = 0.17). Existing evidence indicated that the use of montelukast as an adjuvant therapy had therapeutic efficacy superior to ICS + LABA alone for the treatment of adult patients with CVA. However, further research is needed, especially a combination of high-quality long-term prospective studies and carefully designed RCTs.

Untargeted metabolomics reveals hepatic metabolic disorder in the BTBR mouse model of autism and the significant role of liver in autism.

Autism spectrum disorder (ASD) is a neurodevelopmental disorder, and the etiology is unknown. Metabolic dysfunction is present in patients with ASD. In the current study, untargeted metabolomics was employed to screen the differential metabolites in the liver of BTBR mouse model of autism, and MetaboAnalyst 4.0 was used for metabolic pathway analysis. Mice were killed, and liver samples were collected for untargeted metabolomics analysis and examination of histopathology. Finally, 12 differential metabolites were identified. The intensities of phenylethylamine, 4-Guanidinobutanoic acid, leukotrieneD4, and SM(d18:1/24:1(15Z)) were significantly upregulated (p < .01), and the intensities of estradiol, CMP-N-glycoloylneuraminate, retinoyl β-glucuronide,4-phosphopantothenoylcysteine, aldophosphamide, taurochenodesoxycholic acid, taurocholic acid, and dephospho-CoA were significantly downregulated (p < .01) in the BTBR group compared with C57 control group, indicating that differences between BTBR and C57 groups were observed in metabolic patterns. Disturbed pathways of the BTBR mice involved lipid metabolism, retinol metabolism, and amino acid and energy metabolism, revealing that bile acid-mediated activation of LXRα might contribute to metabolic dysfunction of lipid and leukotriene D4 produced by the activation of 5-LOX led to hepatic inflammation. Pathological changes in the liver tissue, such as hepatocyte vacuolization, and small amounts of inflammatory and cell necrosis, further supported metabolomic results. Moreover, Spearman's rank correlation revealed that there is a strong relationship between metabolites across liver and cortex, suggesting liver may exert action by connecting peripheral and neural systems. These findings were likely to be of pathological importance or a cause/consequence of autism, and may provide insight into key metabolic dysfunction to target potential therapeutic strategies relating to ASD.

Montelukast prevents mice against carbon tetrachloride- and methionine-choline deficient diet-induced liver fibrosis: Reducing hepatic stellate cell activation and inflammation

AimsMontelukast is an antagonist of cysteinyl leukotriene receptor 1 (CysLTR1) that protects against inflammation and oxidative stress. However, the function of montelukast in liver fibrosis remains unknown. In this study, we examined whether the pharmacological inhibition of CysLTR1 could protect mice against hepatic fibrosis. Materials and methodsCarbon tetrachloride (CCl4) and methionine-choline deficient (MCD) diet models were used in this study. The expression of CysLTR1 in liver were detected by RT-qPCR and Western blot analysis. Liver hydroxyproline levels, fibrotic genes expression, serum biochemical indexes and inflammatory factors were used to evaluate the effect of montelukast on liver fibrosis, injury, and inflammation. In vitro, we used the RT-qPCR and Western blot analysis to assess CysLTR1 in mouse primary hepatic stellate cell (HSC) and human LX-2 cell line. The role of montelukast on HSC activation and the underlying mechaisms were determined using RT-qPCR analysis, Western blot and immunostaining assays. Key findingsChronic stimulation from CCl4 and MCD diet upregulated the mRNA and protein levels of CysLTR1 in the liver. Pharmacological inhibition of CysLTR1 by montelukast ameliorated liver inflammation and fibrosis in both models. Mechanistically, montelukast suppressed HSC activation by targeting the TGFβ/Smad pathway in vitro. The hepatoprotective effect of montelukast was also associated with reduced liver injury and inflammation. SignificanceMontelukast suppressed CCl4- and MCD-induced chronic hepatic inflammation and liver fibrosis. CysLTR1 might be a therapeutic target for treating liver fibrosis.

ANALYZE DIFFERENT DRUGS FOR TREATING ALLERGIC RHINITIS IN ADULTS. A CROSS-SECTIONAL STUDY

Background: One of the most frequent and unfavourable medical conditions affecting a significant percentage of adult people worldwide is allergic rhinitis. This study set out to provide a thorough overview of a number of pharmaceutical medications that are often prescribed to adults to treat allergic rhinitis. Study design: a cross-sectional study. Duration and Place of Study: This study was conducted at Department of ENT Hayatabad Medical Complex Hospital Peshawar between 15th Jan 2022 to 15th Jan 2023. Material and Methods: on this study included a cohort of 88 adult patients who had received a verified diagnosis of allergic rhinitis. The study evaluated the effectiveness, safety, and patient-reported results of three main categories of pharmaceuticals: antihistamines, intranasal corticosteroids, and leukotriene receptor antagonists. The participants were allocated randomly to one of the therapy groups and assessed for a duration of 08 weeks. A range of both objective and subjective outcome measures, including symptom scores, ratings of quality of life, and evaluations of adverse events, were documented and subjected to analysis. Results: Thirty of the eighty patients received antihistamines, twenty-seven received intranasal corticosteroids, and thirty-one received leukotriene receptor antagonists. The average age of the groups receiving antihistamines, intranasal corticosteroids, and leukotriene receptor antagonists was 38, 39, and 44 years, respectively. Sixty-six percent of the antihistamine group, fifty-four percent of the intranasal corticosteroids group, and sixty-six percent of the leukotriene receptor antagonist group were female. 50% improved in the group using antihistamines, 71% intranasal corticosteroids, and 12% in the group taking leukotriene receptor antagonists. Antihistamine side effects that were most common were headache (8.33%), tiredness (15%), and nasal dryness (11.67%). The symptoms of intranasal corticosteroids were headache (5.45%), drowsiness (3.64%), and nasal dryness (5.45%). Nasal dryness (8.33%), drowsiness (10%), and gastrointestinal issues (8.33%) were the leukotriene receptor antagonists. Participants who used antihistamines (55%), intranasal corticosteroids (82%), and leukotriene receptor antagonists (67%), reported no adverse effects. These results demonstrate that all three treatments had little side effects and were well tolerated. Conclusion: This study has shown that the administration of intranasal corticosteroids and antihistamines, as opposed to leukotriene receptor antagonists, yields better results for patients with allergic rhinitis in terms of improved quality of life and symptom relief. Keywords: Adult patients, Allergic rhinitis, Pharmacological agents

A feasible HPTLC method for concurrent quantitation of allopurinol-montelukast co-therapy in plasma and evaluation of their hepatic and renal effects in rats: Analytical, biochemical, and histopathological study

Recent studies presented the crucial role of montelukast (MON, a leukotriene receptor antagonist) against gouty arthritis and its protective effect on drug-induced liver and kidney injury. Allopurinol (ALO, a selective xanthine oxidase inhibitor) is also used for treatment of hyperuricemia, however, it induces hepatotoxicity and acute kidney injury. Therefore, this study introduces the first analytical/biochemical/histopathological assay for MON-ALO co-therapy and aims to: inspect the hepatic and renal impacts of ALO, MON and their combination in rats via biochemical and histopathological examinations, propose and validate a facile HPTLC method for concurrent estimation of ALO-MON binary mixture in human plasma, and employ this method to attain the targeted drugs in real rat plasma. First, the cited drugs in human plasma were simultaneously separated utilizing silica gel G 60 F254-TLC plates. The separated bands were scanned at 268 nm demonstrating appropriate linearities (50.0–2000.0 ng band−1 for each drug) and correlations (0.9986 and 0.9992 for ALO and MON, correspondingly). The calculated detection and quantitation limits, as well as recoveries confirmed the method’s reliability. This procedure was validated, and the stability studies were achieved according to Bioanalytical Method Validation Guideline. This work was extended to investigate the possible hepatic and renal effects of ALO, MON and their co-therapy in rats. Using rat’s gastric tube, the following was administered to four groups of male Wistar rats: Group Ia and Ib as control (received either saline or DMSO), Groups II, III, and IV were given MON, ALO, and MON+ALO, respectively. Good correlation between the measured biochemical parameters and the observed histopathological changes was encountered. Considerable drop in aspartate transaminase and alanine transaminase levels, in addition to lower liver damage changes were observed in the combination group compared to MON or ALO-treated groups. Regarding renal changes, ALO-MON co-therapy caused elevation in the serum creatinine and blood urea nitrogen levels when compared to controls and MON- or ALO-treated groups. Severe proteinaceous casts accumulation in kidney tubular lumen, severe congestion, and severe tubular necrosis were also noticed in the combination group. Lastly, this study suggests ALO-MON co-treatment not only as a preventive therapy against gouty arthritis but also as a new line to minimize ALO-induced hepatic injury. However, co-administration of ALO and MON should be further studied to assess the benefits and risks in various tissues, adjust the MON dosing, and monitor its nephrotoxic effect.

Efficacy and safety of fixed-dose combination of Bilastine-Montelukast in adult patients with allergic rhinitis: a phase III, randomized, multi-center, double-blind, active controlled clinical study

Background Histamine and cysteinyl leukotrienes (CysLTs) are potent inflammatory mediators in allergic rhinitis (AR). Studies involving other combinations of antihistaminics (Levocetirizine) and highly selective leukotriene receptor antagonist (LTA) (Montelukast) combination have shown additive benefits and are widely prescribed for AR. Objective Evaluate the efficacy and safety of Bilastine 20 mg and Montelukast 10 mg fixed-dose combination (FDC) therapy in patients with AR. Methods A randomized, double-blind, comparative, parallel, phase III study was conducted to evaluate efficacy and safety of Bilastine 20 mg and Montelukast 10 mg FDC at 16 tertiary care otolaryngology centres in India. Adult patients with AR for one year with IgE antibody positive and 12-h NSS score >36 in 3 days were randomized to receive either Bilastine 20 mg and Montelukast 10 mg or Montelukast 10 mg & Levocetirizine 5 mg tablets for 4 weeks. The change in total symptom score (nasal symptom scores (NSS) & non-nasal symptom scores (NNSS)) from baseline to week 4 was assessed as primary endpoint. Secondary endpoints included changes in TSS, NSS, NNSS, individual symptom scores (ISS), Rhinoconjunctivitis Quality of Life (RQLQ), discomfort due to rhinitis (VAS), and clinical global impression (CGI) scores. Results The change in mean TSS from baseline to week 4 in Test group (16.6 units) was comparable to reference group (17 units) (p= 0.8876). The difference in change in mean NSS, NNSS and ISS from baseline to day 7, 14, 28 were comparable. RQLQ improved from baseline to Day 28. Significant improvements were observed in discomfort due to AR measured by VAS and CGI scores from baseline to day 14 and 28. The safety and tolerability of patients were comparable between the groups. All adverse events (AEs) were mild to moderate in severity. No patient discontinued due to AEs. Conclusions The FDC of Bilastine 20 mg and Montelukast 10 mg was efficacious and well tolerated in Indian patients with AR.

P031 Montelukast antagonising underlying systemic illness

Abstract Background/Aims Eosinophilic granulomatosis with polyangiitis (EGPA) is a rare, multisystemic, autoimmune vasculitis involving small to medium-sized blood vessels. It has a well-established affiliation with atopic syndromes, typically adult-onset asthma and sinusitis. More rare associations are linked with drug side effects such as Montelukast. According to the ‘American College of Rheumatology 1990’, the following criteria yield a sensitivity of 84% in identifying a patient with EGPA. The criteria include: asthma, eosinophilia &amp;gt;10% on differential white cell count, mononeuropathy or polyneuropathy, transient pulmonary infiltrates on chest radiography, paranasal sinus abnormality, and blood vessel biopsy demonstrating extravascular eosinophilia, in a patient with symptoms of systemic vasculitis. The multisystemic involvement of EGPA makes both diagnosis and management difficult as presentations can vary. Methods We report the complex case of a 61 year-old gentleman diagnosed with EGPA. His relevant past medical history includes a diagnosis of Asthma in 2002 (managed with inhaled bronchodilators, corticosteroids, and montelukast), recurrent sinusitis, and lower respiratory tract infections. The patient presented with a one month history of abdominal cramping and bloating. This was associated with nausea, constipation, anorexia, and a week of ‘drenching’ night sweats. His full physical examination during this time was unremarkable. Results He had a normal CT Abdomen Pelvis and colonoscopy. His admission chest radiograph demonstrated bilateral parenchymal lung changes. This was followed by a CT Thorax showing bilateral upper and lower lobe bronchiectasis. Mediastinal and hilar adenopathy consistent with a diagnosis of allergic bronchopulmonary aspergillosis with associated reactive adenopathy. His laboratory investigations showed eosinophilia (21.68) and leucocytosis (32.7). In view of these results, an autoantibody screen was sent showing positive ANCA and positive anti-Myeloperoxidase antibodies(MPO titre 55). Two days into his admission he developed pain and paralysis of his right upper limb. He reported marked fatigue followed by a petechial, non-blanching, vasculitic rash on both ankles. Neurological examination reflected a subacute symmetrical sensory and motor polyneuropathy predominantly involving the right side with bilateral foot drop. MRI Brain demonstrated an established infarct in the left external capsule. He was commenced on high dose aspirin. Due to high suspicion for EGPA, methylprednisolone was commenced for 5 days, followed by tapering oral corticosteroid therapy and Rituximab therapy. A skin punch biopsy showed ‘ a vasculopathic type reaction with small vessel vasculitis, associated mixed inflammatory infiltrate which includes some eosinophils’ confirmed his diagnosis. Conclusion A topic of particular relevance to this case is the association between EGPA and montelukast. It has been hypothesised that there may be a relationship between Leukotriene Receptor Antagonist Therapy, specifically Montelukast, with the pathogenesis of EGPA. Some research suggests that treatment with Montelukast permits the decreased need for oral corticosteroids for asthma control. Therefore, suggesting that EGPA could have been masked by corticosteroid therapy. Disclosure Á. Connerton: None.

Modulation of the 5-Lipoxygenase Pathway by Chalcogen-Containing Inhibitors of Leukotriene A4 Hydrolase.

The 5-lipoxygenase (5-LOX) pathway gives rise to bioactive inflammatory lipid mediators, such as leukotrienes (LTs). 5-LOX carries out the oxygenation of arachidonic acid to the 5-hydroperoxy derivative and then to the leukotriene A4 epoxide which is converted to a chemotactic leukotriene B4 (LTB4) by leukotriene A4 hydrolase (LTA4H). In addition, LTA4H possesses aminopeptidase activity to cleave the N-terminal proline of a pro-inflammatory tripeptide, prolyl-glycyl-proline (PGP). Based on the structural characteristics of LTA4H, it is possible to selectively inhibit the epoxide hydrolase activity while sparing the inactivating, peptidolytic, cleavage of PGP. In the current study, chalcogen-containing compounds, 4-(4-benzylphenyl) thiazol-2-amine (ARM1) and its selenazole (TTSe) and oxazole (TTO) derivatives were characterized regarding their inhibitory and binding properties. All three compounds selectively inhibit the epoxide hydrolase activity of LTA4H at low micromolar concentrations, while sparing the aminopeptidase activity. These inhibitors also block the 5-LOX activity in leukocytes and have distinct inhibition constants with recombinant 5-LOX. Furthermore, high-resolution structures of LTA4H with inhibitors were determined and potential binding sites to 5-LOX were proposed. In conclusion, we present chalcogen-containing inhibitors which differentially target essential steps in the biosynthetic route for LTB4 and can potentially be used as modulators of inflammatory response by the 5-LOX pathway.

The Effects of Endogenous Cannabinoids on the Mammalian Respiratory System: A Scoping Review of Cyclooxygenase-Dependent Pathways.

Introduction: The endogenous cannabinoid (endocannabinoid) system is an emerging target for the treatment of chronic inflammatory disease with the potential to advance treatment for many respiratory illnesses. The varied effects of endocannabinoids across tissue types makes it imperative that we explore their physiologic impact within unique tissue targets. The aim of this scoping review is to explore the impact of endocannabinoid activity on eicosanoid production as a measure of human airway inflammation. Methods: A scoping literature review was conducted according to PRISMA-ScR (Preferred Reporting Items for Systematic reviews and Meta-Analyses extension for Scoping Reviews) guidelines. Search strategies using MeSH terms related to cannabinoids, eicosanoids, cyclooxygenase (COX), and the respiratory system were used to query Medline, Embase, Cochrane, CINAHL, Web of Science, and Biosis Previews in December 2021. Only studies that investigated the relationship between endocannabinoids and the eicosanoid system in mammalian respiratory tissue after 1992 were included. Results: Sixteen studies were incorporated in the final qualitative review. Endocannabinoid activation increases COX-2 expression, potentially through ceramide-dependent or p38 and p42/44 Mitogen-Activated Protein Kinase pathways and is associated with a concentration-dependent increase in prostaglandin (PG)E2. Inhibitors of endocannabinoid hydrolysis found either an increase or no change in levels of PGE2 and PGD2 and decreased levels of leukotriene (LT)B4, PGI2, and thromboxane A2 (TXA2). Endocannabinoids increase bronchial epithelial cell permeability and have vasorelaxant effects in human pulmonary arteries and cause contraction of bronchi and decreased gas trapping in guinea pigs. Inhibitors of endocannabinoid hydrolysis were found to have anti-inflammatory effects on pulmonary tissue and are primarily mediated by COX-2 and activation of eicosanoid receptors. Direct agonism of endocannabinoid receptors appears to play a minor role. Conclusion: The endocannabinoid system has diverse effects on the mammalian airway. While endocannabinoid-derived PGs can have anti-inflammatory effects, endocannabinoids also produce proinflammatory conditions, such as increased epithelial permeability and bronchial contraction. These conflicting findings suggest that endocannabinoids produce a variety of effects depending on their local metabolism and receptor agonism. Elucidation of the complex interplay between the endocannabinoid and eicosanoid pathways is key to leveraging the endocannabinoid system as a potential therapeutic target for human airway disease.

Expression of Concern: Leukotriene D4 activates MAPK through a Ras-independent but PKCε-dependent pathway in intestinal epithelial cells.

There are potential issues in J. Cell Sci. (2002) 115, 1883–1893 (doi:10.1242/jcs.115.9.1883).A possible duplication of the LTD4+PP1 and LTD4+ PD98059 bands in Fig 5E was highlighted to us via the PubPeer website. Owing to the period of time that has passed since the experiments were conducted, the authors have not been able to provide original data for this blot. They have conducted analyses which they feel show the two blots to be different; however, without the original data, it is difficult to conclude if the bands are duplicated, so the journal is publishing this Expression of Concern to alert readers to this issue.