Cysteinyl Leukotriene Receptor Antagonist Research Articles

MK-571, a Cysteinyl Leukotriene Receptor 1 Antagonist, Inhibits Hepatitis C Virus Replication.

The quinoline MK-571 is the most commonly used inhibitor of multidrug resistance protein-1 (MRP-1) but was originally developed as a cysteinyl leukotriene receptor 1 (CysLTR1) antagonist. While studying the modulatory effect of MRP-1 on anti-hepatitis C virus (HCV) direct-acting antiviral (DAA) efficiency, we observed an unexpected anti-HCV effect of compound MK-571 alone. This anti-HCV activity was characterized in Huh7.5 cells stably harboring a subgenomic genotype 1b replicon. A dose-dependent decrease of HCV RNA levels was observed upon MK-571 administration, with a 50% effective concentration (EC50 ± standard deviation) of 9 ± 0.3 μM and a maximum HCV RNA level reduction of approximatively 1 log10 MK-571 also reduced the replication of the HCV full-length J6/JFH1 model in a dose-dependent manner. However, probenecid and apigenin homodimer (APN), two specific inhibitors of MRP-1, had no effect on HCV replication. In contrast, the CysLTR1 antagonist SR2640 increased HCV-subgenomic replicon (SGR) RNA levels in a dose-dependent manner, with a maximum increase of 10-fold. In addition, a combination of natural CysLTR1 agonist (LTD4) or antagonists (zafirlukast, cinalukast, and SR2640) with MK-571 completely reversed its antiviral effect, suggesting its anti-HCV activity is related to CysLTR1 rather to MRP-1 inhibition. In conclusion, we showed that MK-571 inhibits HCV replication in hepatoma cell cultures by acting as a CysLTR1 receptor antagonist, thus unraveling a new host-virus interaction in the HCV life cycle.

Montelukast Has no Impact on the Systemic Production of TGFβ-1 in Patients with Nasal Polyposis Associated with Aspirin Intolerance.

Introduction Nasal polyposis is a disease characterized by a mechanical dysfunction of the nasal mucosa, closely related to the unique makeup of its extracellular matrix, which develops as the result of an anomalous tissue remodeling process. Transforming growth factor beta 1 (TGF-β1) is reduced not only in the nasal polypoid tissue, but also in the plasma of aspirin-intolerant patients. These patients exhibit an imbalance in the production of eicosanoids characterized by an increase in leukotrienes. Thus, it is important that the relationship between the production of leukotrienes and TGF-β1 be assessed. Objective To evaluate the effects of the cysteinyl leukotriene (CysLT) receptor antagonist montelukast on the systemic production of TGF-β1 in patients with nasal polyposis, with or without concomitant aspirin intolerance. Methods The sample comprised 48 individuals with diagnosis of nasal polyposis and 15 healthy controls for comparison of the baseline TGF-β1 levels in the peripheral blood and after treatment with CysLT receptor antagonist montelukast in the nasal-polyposis group. Results There was no difference in the change in TGF-β1 levels after the treatment with montelukast in the subgroup of patients with polyposis and asthma ( p = 0.82) and in the subgroup with polyposis, asthma, and aspirin intolerance ( p = 0.51). Conclusion we found no impact of the therapy with a leukotriene receptor blocker on the production of TGF-β1, making the antileukotriene therapy a highly questionable choice for the treatment of nasal polyposis, particularly from the standpoint of seeking to modify the remodeling process in this disease.

Montelukast Potentiates the Antiinflammatory Effect of NSAIDs in the Rat Paw Formalin Model and Simultaneously Minimizes the Risk of Gastric Damage

Although the cysteinyl leukotriene receptor antagonist montelukast has been recognized for its antiinflammatory action, little information is available on whether this effect would be intensified if montelukast is co‐administered with nonsteroidal antiinflammatory drugs (NSAIDs). Here, we tested the hypothesis that simultaneous exposure to montelukast and NSAIDs elicits more efficacious control of histopathological and inflammatory signals in the rat paw formalin model. We also determined whether montelukast could improve gastric damage caused by NSAIDs and associated inflammatory insults. The individual treatment of rats with montelukast (20 mg/kg), diclofenac (nonselective COX1/COX2 inhibitor, 10 mg/kg), or celecoxib (selective COX2 inhibitor, 10 mg/kg) significantly reduced the formalin‐induced increases in (i) paw edema, (ii) necrotic debris and keratinized stratified squamous epithelium, (iii) paw protein expressions of iNOS and COX2, and (iv) serum IL‐6 and LTB4. These favorable histopathological and molecular effects were accentuated in rats treated with montelukast plus diclofenac or celecoxib. Alternatively, montelukast reduced the diclofenac‐evoked gastric damage (lesions and hyperemia) and rises in gastric TNFα levels, but it failed to alter the concomitant reductions in gastric COX1 expression and PGE2 content. Unlike diclofenac, normal gastric mucosal and COX1/PGE2 patterns were observed in celecoxib‐treated animals. Overall, the current data provide evidence that montelukast boosts the antiinflammatory action of NSAIDs while diminishing the potential of gastric damage and inflammation.

Phase 2 trial of montelukast for prevention of pain in sickle cell disease

AbstractCysteinyl leukotrienes (CysLTs) are lipid mediators of inflammation. In patients with sickle cell disease (SCD), levels of CysLTs are increased compared with controls and associated with a higher rate of hospitalization for pain. We tested the hypothesis that administration of the CysLT receptor antagonist montelukast would improve SCD-related comorbidities, including pain, in adolescents and adults with SCD. In a phase 2 randomized trial, we administered montelukast or placebo for 8 weeks. The primary outcome measure was a >30% reduction in soluble vascular cell adhesion molecule 1 (sVCAM), a marker of vascular injury. Secondary outcome measures were reduction in daily pain, improvement in pulmonary function, and improvement in microvascular blood flow, as measured by laser Doppler velocimetry. Forty-two participants with SCD were randomized to receive montelukast or placebo for 8 weeks. We found no difference between the montelukast and placebo groups with regard to the levels of sVCAM, reported pain, pulmonary function, or microvascular blood flow. Although montelukast is an effective treatment for asthma, we did not find benefit for SCD-related outcomes. This clinical trial was registered at www.clinicaltrials.gov as #NCT01960413.

Mechanisms underlying the protective effect of leukotriene receptor antagonist montelukast against doxorubicin induced testicular injury in rats

The obligatory use of cytotoxic drugs to face the malignant tumors results in survivors that suffer from long term health problems. Fertility problems, especially in young boys, exert one of the major consequences of chemotherapy treatment that needs resolution. We investigate the potential effect of the cysteinyl leukotriene receptor antagonist montelukast on doxorubicin-induced testicular damage. Five groups of adult Wistar male rats were subjected to the following treatment; vehicle for the control group, montelukast (20 mg/kg orally daily for 10 days) for the drug control, doxorubicin (12 mg/kg intraperitoneal injection once at 5th day) for the toxic group, montelukast at 10 mg/kg + doxorubicin, montelukast at 20 mg/kg + doxorubicin. The period of the experiment was 10 days administration of montelukast, while doxorubicin was injected at the 5th day. Results of serum testosterone, testicular lipid peroxidation, antioxidant status, and histopathology revealed protection of montelukast against doxorubicin-induced testicular damage. The pro-apoptotic caspase 3 and the pro-inflammatory tumor necrosis factor-alpha were examined immunohistochemically and showed a significant decrease with montelukast treatment as compared to doxorubicin group. Doxorubicin increased gene expression of matrix metalloproteinase 9 and decreased peroxisome proliferator activated receptor gamma. Montelukast treatment restored their expressions to normal values.In conclusion, montelukast administration can ameliorate the testicular damage induced by doxorubicin based on its anti-inflammatory, antioxidant and anti-apoptotic effects as well as by of modulation of important genes expression.

Radioprotective effects of montelukast, a selective leukotriene CysLT1 receptor antagonist, against nephrotoxicity induced by gamma radiation in mice.

In this study, we evaluated the renal protective effects of montelukast (MLK) against ionizing radiation (IR) induced nephrotoxicity in mice. Radioprotective effects of MLK were assessed by biochemical analysis including measurements of kidney malondialdehyde (MDA), reduced glutathione (GSH), and serum creatinine and urea levels. Besides, for further evaluation of protective effects of MLK on renal system, 99m Tc-dimercaptosuccinic acid (DMSA) has been applied. The total antioxidant capacity of MLK was measured by using 1,1-diphenyl-2-picryl hydrazyl radical reagents and compared with butylated hydroxyl toluene standard antioxidant. The biochemical evaluation revealed that better results have been achieved for the groups administered with MLK than the only radiation group. Besides only IR-treated mice group, those treated with MLK demonstrated a significant decrease in urea and creatinine levels. Statistically, significant differences of MDA and SHG levels (P < .05) were found between the radiation group and MLK plus IR-treated group. Also, 99m Tc-DMSA kidney uptake value (%ID/g) was observed lower for MLK plus IR-treated mice group than only radiation-treated mice group. According to our findings, MLK has a potential role to be used as a renal protective agent against gamma radiation in radiotherapy.

Montelukast ameliorates doxorubicin-induced cardiotoxicity via modulation of p-glycoprotein and inhibition of ROS-mediated TNF-α/NF-κB pathways

Doxorubicin (DOX) cardiotoxicity remains an obstacle to clinical use. The current study examined the possible role of montelukast (ML), which is a cysteinyl leukotrienes receptor antagonist against DOX-induced cardiotoxicity. Male Wistar rats were divided into five groups. The control group, ML group, DOX-challenged group, and DOX/ML-treated groups received ML10 and 20 mg/kg/day for 14 days. Cardiac enzymes; lactate dehydrogenase (LDH); and creatine kinase MB (CK-MB) isoenzymes in serum were measured. Cardiac oxidative/antioxidative parameters were also measured. Cardiac samples were examined for histological images and immunohistochemical expression of tumor necrosis factor alpha (TNF-α)/survivin. Quantitative real-time-polymerase chain reaction was used to detect levels of interleukin (IL)-1β/caspase-3 mRNA. The levels of P-glycoprotein (P-gp), nuclear factor-kappa B , and reactive oxygen species were estimated by enzyme-linked immunosorbent assay. DOX increased serum cardiac enzymes along with oxidative, inflammatory, and apoptotic markers. Both doses of ML significantly ameliorated cardiac enzymes and attenuated all oxidative stress parameters with the enhancement of P-gp activity. It was concluded that ML may be a valuable cardioprotective adjuvant during DOX use.

CysLT1 Receptor Antagonists Pranlukast and Zafirlukast Inhibit LRRC8-Mediated Volume Regulated Anion Channels Independently of the Receptor

Volume Regulated Anion Channels (VRACs) encoded by the LRRC8 gene family play critical roles in myriad cellular processes and might represent druggable targets. The dearth of pharmacological compounds available for studying VRAC physiology led us to perform a high-throughput screen (HTS) of 1,184 of FDA-approved drugs for novel VRAC modulators. We discovered the cysteinyl leukotriene receptor 1 (CysLT1R) antagonist, Pranlukast, as a novel inhibitor of endogenous VRAC expressed in HEK293 cells. Pranlukast inhibits VRAC voltage-independently, reversibly, and dose-dependently with a maximal efficacy of only ∼50%. The CysLT1R pathway has been implicated in activation of VRAC in other cell types, prompting us to test whether Pranlukast requires the CysLT1R for inhibition of VRAC. Quantitative PCR analysis demonstrated that CYSLTR1 mRNA is virtually undetectable in HEK293 cells. Furthermore, the CysLT1R agonist LTD4 had no effect on VRAC activity and failed to stimulate Gq-coupled receptor signaling. Heterologous expression of the CysLT1R reconstituted LTD4-CysLT1R-Gq-calcium signaling in HEK293 cells but had no effect on VRAC inhibition by Pranlukast. Finally, we show the CysLT1R antagonist Zafirlukast inhibits VRAC with an IC50 of ∼17 µM and does so with full efficacy. To assess the binding the site of Zafirlukast on VRAC we used homomeric LRRC8A, and various homomeric LRRC8 chimeras, showing Zafirlukast inhibits each construct equally, suggesting Zafirlukast may be binding in a conserved region among LRRC8A, LRRC8C, LRRC8D, and LRRC8E subunits. In summary, our data suggest that both Pranlukast and Zafirlukast are likely direct channel inhibitors that work independently of the CysLT1R. This study provides clarifying insights into the putative role of leukotriene signaling in modulation of VRAC and identifies two new chemical scaffolds that can be used for development of more potent and specific VRAC inhibitors.

Corticosteroid reduction by addition of cetirizine and montelukast in biopsy-proven minimal-change nephrotic syndrome concomitant with allergic disorders

Recent reports suggest helper T-cell abnormalities in minimal-change nephrotic syndrome (MCNS), which often complicate allergic disorders that show a similar helper T-cell profile with Th2/Th17 predominance. However, the effect of anti-allergy therapy on MCNS remains unknown. This retrospective study included 51 patients with biopsy-proven MCNS recruited between November 2012 and October 2015, with follow-up through November 2017. We analyzed relapse and temporal daily corticosteroid dose with and without co-administration of histamine H1 receptor antagonist, cetirizine, and cysteinyl-leukotriene receptor antagonist, montelukast, as well as between baseline and after follow-up. Thirteen patients were treated with cetirizine and montelukast in addition to conventional therapy, whereas 38 patients were treated by conventional therapy only, consisting of corticosteroids and immunosuppressants. To adjust for baseline clinical characteristics, a 1:1 propensity score–matched model was applied. The clinical characteristics of the two groups after matching were similar at baseline. The treatment group showed a significant reduction in the lowest daily dose of oral prednisolone throughout the entire treatment course after the study compared to that of baseline (p < 0.025), which was not observed in the control group (p = 0.37), and showed significantly higher percentage of patients establishing corticosteroid-free state for the first time throughout the entire treatment course by addition of cetirizine and montelukast compared to the control group (p < 0.025). The study shows, for the first time, the steroid sparing effect of cetirizine and montelukast in addition to conventional treatment in MCNS patients with concomitant allergies.

Zafirlukast, a Cysteinyl Leukotriene Receptor 1 Antagonist, Reduces the Effect of Advanced Glycation End-Products in Rat Renal Mesangial Cells In Vitro

BackgroundZafirlukast is an antagonist of cysteinyl leukotriene receptor 1 (CysLTR1). Advanced glycation end-products (AGEs) are formed by the glycation of lipids and proteins in hyperglycemia, including diabetes mellitus. Zafirlukast has not previously been studied in diabetic nephropathy. This study aimed to investigate the effects of zafirlukast on rat renal mesangial cells cultured with AGEs in vitro.Material/MethodsMesangial cells were cultured in AGEs (0, 20, 50, 100 μg/ml), and with AGEs (100 μg/ml) and zafirlukast (2.5 μm, 5 μm, and 100 μm). An enzyme-linked immunoassay (ELISA) was used to measure the levels of tumor necrosis factor-α (TNF-α), interleukin-1β (IL-1β), IL-6, and monocyte chemoattractant protein-1 (MCP-1). Reactive oxygen species (ROS) were assessed by intracellular fluorescence measurement of 2′-7′-dichlorodihydrofluorescein diacetate (DCFH-DA), and detection kits were used to measure malondialdehyde (MDA), lactate dehydrogenase (LDH), glutathione peroxidase (GSH-Px), and superoxide dismutase (SOD). Cell apoptosis was assessed by flow cytometry, and Western blot was used to measure protein levels.ResultsIn mesangial cells cultured with AGEs, markers of inflammation, oxidative stress, and apoptosis and levels of CysLTR1 increased, and these effects were reduced by zafirlukast in a dose-dependent manner. The effects of zafirlukast as a CysLTR1 antagonist protected mesangial cells from the effects of AGE in vitro.ConclusionsZafirlukast, a CysLTR1 antagonist, reduced the levels of inflammatory cytokines, markers of oxidative stress, and cell apoptosis induced by AGE in mesangial cells in a dose-dependent way. Future in vivo studies are needed to investigate the potential role for zafirlukast in models of diabetic nephropathy.

Current state and future prospect of the therapeutic strategy targeting cysteinyl leukotriene metabolism in asthma.

Asthma is an allergic disorder with dominant type 2 airway inflammation, and its prevalence is increasing worldwide. Inhalation of corticosteroids is the primary treatment for asthma along with add-on drugs, including long-acting β2 agonists and/or cysteinyl leukotriene (cys-LT) receptor antagonists, in patients with poorly controlled asthma. Cys-LTs are composed of leukotriene C4 (LTC4), LTD4, and LTE4, which are enzymatically metabolized from arachidonic acid. These molecules act as inflammatory mediators through different types of high-affinity receptors, namely, CysLT1, CysLT2, and CysLT3 (also named as GPR99). CysLT1 antagonists possessing anti-inflammatory and bronchodilatory effects can be orally administered to patients with asthma. Recently, molecular biology-based studies have revealed the mechanism of inflammatory responses via other receptors, such as CysLT2 and CysLT3, as well as the importance of upstream inflammatory regulators, including type 2 cytokines (e.g., interleukins 4 and 5), in controlling cys-LT metabolism. These findings indicate the therapeutic potential of pharmacological agents targeting cys-LT metabolism-related receptors and enzymes, and antibody drugs neutralizing or antagonizing type 2 cytokines. This review focuses on the current state and future prospect of the therapeutic strategy targeting cys-LT metabolism.

Montelukast Prevents Mice Against Acetaminophen-Induced Liver Injury.

Acetaminophen (APAP) is a widely used over-the-counter antipyretic and analgesic drug. Overdose of APAP is the leading cause of hospital admission for acute liver failure. Montelukast is an antagonist of cysteinyl leukotriene receptor 1 (Cysltr1), which protects from inflammation and oxidative stress. However, the function of montelukast in APAP-induced hepatotoxicity remains unknown. In this study, we examined whether pharmacological inhibition of Cystlr1 could protect mice against APAP-induced hepatic damage. We found that APAP treatment upregulated messenger RNA and protein levels of Cysltr1 both in vitro and in vivo. Pharmacological inhibition of Cysltr1 by montelukast ameliorated APAP-induced acute liver failure. The hepatoprotective effect of montelukast was associated with upregulation of hepatic glutathione/glutathione disulfide level, reduction in c-Jun-NH2-terminal kinase activation and oxidative stress. In mouse primary hepatocytes, inhibition of Cysltr1 by montelukast ameliorated the expression of inflammatory-related genes and APAP-induced cytotoxicity. We conclude that montelukast may be used to treat APAP-induced acute hepatic injury.

CysLT1 receptor antagonists pranlukast and zafirlukast inhibit LRRC8-mediated volume regulated anion channels independently of the receptor.

Volume-regulated anion channels (VRACs) encoded by the leucine-rich repeat containing 8 (LRRC8) gene family play critical roles in myriad cellular processes and might represent druggable targets. The dearth of pharmacological compounds available for studying VRAC physiology led us to perform a high-throughput screen of 1,184 of US Food and Drug Administration-approved drugs for novel VRAC modulators. We discovered the cysteinyl leukotriene receptor 1 (CysLT1R) antagonist, pranlukast, as a novel inhibitor of endogenous VRAC expressed in human embryonic kidney 293 (HEK293) cells. Pranlukast inhibits VRAC voltage-independently, reversibly, and dose-dependently with a maximal efficacy of only ~50%. The CysLT1R pathway has been implicated in activation of VRAC in other cell types, prompting us to test whether pranlukast requires the CysLT1R for inhibition of VRAC. Quantitative PCR analysis demonstrated that CYSLTR1 mRNA is virtually undetectable in HEK293 cells. Furthermore, the CysLT1R agonist leukotriene D4 had no effect on VRAC activity and failed to stimulate Gq-coupled receptor signaling. Heterologous expression of the CysLT1R reconstituted LTD4-CysLT1R- Gq-calcium signaling in HEK293 cells but had no effect on VRAC inhibition by pranlukast. Finally, we show the CysLT1R antagonist zafirlukast inhibits VRAC with an IC50 of ~17 µM and does so with full efficacy. Our data suggest that both pranlukast and zafirlukast are likely direct channel inhibitors that work independently of the CysLT1R. This study provides clarifying insights into the putative role of leukotriene signaling in modulation of VRAC and identifies two new chemical scaffolds that can be used for development of more potent and specific VRAC inhibitors.

Prevalence of Montelukast Use as an Add-On Therapy among Iraqi Asthmatics on Treatment Attending Al-Kindy Teaching Hospital and Al-Zahraa Center of Asthma and Allergy.

BACKGROUND:Montelukast (Singulair) is a cysteinyl leukotriene receptor antagonist, used for the maintenance treatment of asthma and to relieve symptoms of seasonal allergic rhinitis and asthma, also used for exercise-induced bronchospasm.AIM:This study was performed to determine the prevalence of Montelukast use as an add-on therapy among Iraqi asthmatic patients on treatment. Comparing the effectiveness of regimens with and without montelukast.METHODS:This descriptive cross-sectional study was carried out on 73 Iraqi asthmatic patients on treatment of both sexes with age range (18-60) years old, attending Al-Kindy Teaching Hospital and Al-Zahraa Centre of Asthma and Allergy, Baghdad, for the period between February and March 2017. A questionnaire was specifically prepared to meet the objectives and was used to collect the data of the study.RESULTS:There was a significant statistical reduction of frequency in asthmatic attacks after Montelukast treatment (p-value < 0.05). Out of 73 patients, 39 were males, and 34 were females, 46 were jobless, 37 were married, 63 were urban residents, 63 were educated. Prevalence of exacerbation factors was as following: infection was found in 60.3% of the patients, exercise in 57.5%, dust in 72.6%, smoking in 60.6%, food in 24.7%, others (stress, perfumes) in 20.5%. The prevalence of Montelukast use in this study was 46% (34 patients). Out of 34 patients using Montelukast, 28 were using inhaled salbutamol, 5 were using oral salbutamol, 15 were using inhaled corticosteroids, 9 were using systematic corticosteroids, 2 were using xanthines, and 6 were using ketotifen.CONCLUSION:Montelukast was used as add-on therapy with the inhaled corticosteroids to reduce the required dose of inhaled corticosteroids also the use of Montelukast lead to reduced number of exacerbations which will be reflected on the use of inhaled salbutamol and systematic corticosteroids. Also, Montelukast was superior to xanthines and ketotifen as an add-on therapy.

Effect of Montelukast on Bronchopulmonary Dysplasia (BPD) and Related Mechanisms.

BackgroundBronchopulmonary dysplasia (BPD) is a chronic lung disease common in preterm infants. Montelukast, an effective cysteinyl leukotriene (cysLT) receptor antagonist, has a variety of pharmacological effects and has protective effects against a variety of diseases. Currently, the efficacy and safety of montelukast sodium in treating BPD has been revealed, however, the precise molecular mechanism of the effect of montelukast on BPD development remain largely unclear. Therefore, this study aimed to investigate the effect and mechanism of montelukast on BPD in vivo and in vitro.Material/MethodsA mouse BPD model and hyperoxia-induced lung cell injury model were established and treated with montelukast. Then mean linear intercept (MLI), radial alveolar count (RAC), lung weight/body weight (LW/BW) ratio, pro-inflammatory factors, and oxidative stress-related factors in lung tissues were determined. Cell viability and apoptosis were detected using MTT assay and flow cytometer respectively.ResultsThe results showed that montelukast treatment relieved mouse BPD, evidenced by increased RAC and decreased MLI and LW/BW ratios. We also found that montelukast treatment reduced pro-inflammatory factors (TNF-α, IL-6, and IL-1β) production, enhanced superoxide dismutase (SOD) activity, and reduced malondialdehyde (MDA) content in the lung tissues of BPD mice. Besides, montelukast eliminated the reduced cell viability and enhanced cell apoptosis induced by hyperoxia exposure in vitro. Moreover, the upregulated pro-inflammatory factors production and p-p65 protein level in lung cells caused by hyperoxia were decreased by montelukast treatment.ConclusionsMontelukast protected against mouse BPD induced by hyperoxia through inhibiting inflammation, oxidative stress, and lung cell apoptosis.

Protective effect of cysteinyl leukotriene receptor antagonist montelukast in bleomycin-induced pulmonary fibrosis.

This study aims to investigate the early- and late-term effects of pharmacological inhibition of cysteinyl leukotriene activity by using montelukast in bleomycin-induced inflammatory and oxidative lung injury in an animal model. The study included 48 male Wistar albino rats (weighing 250 g to 300 g). Rats were administered intratracheal bleomycin or saline and assigned into groups to receive montelukast or saline. Bronchoalveolar lavage fluid and lung tissue samples were collected four and 15 days after bleomycin administration. Bleomycin resulted in significant increases in tumor necrosis factor-alpha levels (4.0±1.4 pg/mL in controls vs. 44.1±14.5 pg/mL in early-term vs. 30.3±5.7 pg/mL in late-term, p<0.001 and p<0.001, respectively), transforming growth factor beta 1 levels (28.6±6.6 pg/mL vs. 82.3±14.1 pg/mL in early-term vs. 60.1±2.9 pg/mL in late-term, p<0.001 and p<0.001, respectively), and fibrosis score (1.85±0.89 in early-term vs. 5.60±1.14 in late-term, p<0.001 and p<0.01, respectively). In bleomycin exposed rats, collagen content increased only in the late-term (15.3±3.0 ?g/mg in controls vs. 29.6±9.1 ?g/mg in late-term, p<0.001). Montelukast treatment reversed all these biochemical indices as well as histopathological alterations induced by bleomycin. Montelukast attenuates bleomycin-induced inflammatory and oxidative lung injury and prevents lung collagen deposition and fibrotic response. Thus, cysteinyl leukotriene receptor antagonists might be regarded as new therapeutic agents for idiopathic pulmonary fibrosis.

Montelukast attenuates rotenone-induced microglial activation/p38 MAPK expression in rats: Possible role of its antioxidant, anti-inflammatory and antiapoptotic effects

Montelukast (MK),a cysteinyl leukotriene (CysLT1) receptor antagonist, latterly exhibited a remarkable neuroprotective activity in various neurodegenerative disorders. This study aims to elucidate the neuroprotective effect of MK in rotenone-induced Parkinson's disease(PD) model in rats. Ninety six male rats were split into four groups: vehicle control (0.2 ml/kg/48 h, sc), MK (10 mg/kg/day, ip), rotenone (1.5 mg/kg/48 h, sc.) and rotenone pretreated with MK. Rotenone treatment led to significant reduction in motor functioning and elevation in oxidative stress markers. Additionally, upregulation of p38 mitogen-activated protein kinase (p38 MAPK) and CysLT1 receptor expressions were anchored with enhanced striatal microglial activation generating a severe neuro-inflammatory milieu. Furthermore, an augmentation in p53 expression and cleaved caspases-3 activity increased apoptotic neurodegeneration synchronized with reduction of striatal tyrosine hydroxylase (TH) content. Changes in neuronal morphology was also noted. MK administration significantly mitigated motor impairment and rise in oxidative stress mediators. As well, the anti-inflammatory activity of MK was manifested by hindering the principal controller of inflammatory pathway, nuclear factor-kappa B, followed by its downstream pro-inflammatory cytokines (tumor necrosis factor-alpha and interleukin-1 beta), by attenuating striatal microglial activation and hampering the expression of both p38 MAPK and CysLT1. Moreover, MK revealed a decline in p53 expression with its downstream cleaved caspases-3 which resulted in preservation of striatal TH terminals as verified by increased striatal TH content and improvement in the histopathological changes incited by rotenone. In conclusion, MK endowed neuroprotective effects in rotenone-induced PD animal model via attenuation of microglial cell activation and p38 MAPK expression.

Montelukast, a CysLT1 receptor antagonist, reduces colon cancer stemness and tumor burden in a mouse xenograft model of human colon cancer

Inflammation is implicated in the etiology of sporadic colon cancer (CC), which is one of the leading causes of cancer-related deaths worldwide. Here, we report that inhibition of the inflammatory receptor CysLT1 through its antagonist, montelukast, is beneficial in minimizing stemness in CC and thereby minimizing tumor growth in a mouse xenograft model of human colon cancer. Upon treatment with montelukast, colonospheres derived from HT-29 and SW-480 human colon cancer cells exhibited a significant phenotypic change coupled with the downregulation of mRNA and protein expression of cancer stem cell (CSC) markers ALDH1 and DCLK1. Moreover, montelukast reduced the size of HT-29 cell-derived tumors in mice. The reduction in tumor size was associated with decreased levels of ALDH1A1, DCLK1, BCL2 mRNA and macrophage infiltration into the tumor tissue. Interestingly, this treatment elevated levels of the tumor suppressor 15-PGDH while reducing COX-2 expression. Our data highlight the association of CysLT1R with CSCs and demonstrate that inhibition of CysLT1R could prove beneficial in minimizing CSC-induced tumor growth. This work advances the notion that targeting CSCs is a promising approach to improve outcomes in those afflicted with colon cancer.

Zafirlukast in combination with pseudohypericin attenuates spinal cord injury and motor function in experimental mice.

BackgroundBiosynthesis of leukotriene (LT) by arachidonic acid involves 5-lipoxygenase (5-LO) as an important precursor. Here, we evaluated the role of pseudohypericin (PHP) for its postulated 5-LO inhibitory activity along with a Cys-LT receptor antagonist zafirlukast (ZFL) against inflammatory response and tissue injury in mice.Materials and methodsThe spinal injury was induced by two-level laminectomy of T6 and T7 vertebrae. The inflammation was assessed by histology, inflammatory mediators by enzyme-linked immunosorbent assay, apoptosis by Annexin-V, FAS staining, terminal deoxynucleoti-dyltransferase-mediated UTP end labeling (TUNEL) assay and expression of Bax and Bcl-2 by Western blot. Effect on motor recovery of hind limbs was evaluated for 10 days postinjury.ResultsThe spinal injury resulted in tissue damage, apoptosis, edema, infiltration of neutrophils with increased expression of tumor necrosis factor-α (TNF-α) and cyclooxygenase-2 (COX-2). The spinal tissue showed elevated levels of prostaglandin E2 (PGE2), and LTB4 and increased phosphorylation of injured extracellular signal-regulated kinase-1/2 (ERK1/2). The PHP, ZFL and combination decreased inflammation, tissue injury and infiltration of neutrophils. Treatment also decreased the levels of PGE2, phosphorylation of extracellular signal-regulated kinase-1/2 (pERK 1/2), LT, TNF-α and COX-2 with a marked reduction in apoptosis and improved the motor function.ConclusionThe present study confirmed 5-LO antagonist activity of PHP and established its neuroprotective role along with ZFL.

Montelukast inhibits RANKL‑induced osteoclast formation and bone loss via CysLTR1 and P2Y12.

Osteoclasts (OCs) are resorptive cells responsible for bone erosion in diseases, including osteoporosis, periodontitis and rheumatoid arthritis. Montelukast is a cysteinyl leukotriene receptor 1 (CysLTR1) antagonist clinically used for the treatment of asthma. In the present study, the role of CysLTR1 on OC formation and bone loss was investigated using montelukast. Montelukast inhibited receptor activator of nuclear factor‑κB ligand (RANKL)‑induced OC formation in cultures of mouse bone marrow macrophages. Additionally, montelukast suppressed actin ring formation and bone resorption activity of differentiated OCs. The inhibitory effect of montelukast was associated with impaired activation of extracellular signal‑regulated kinase, AKT serine/threonine kinase, and/or phospholipase Cγ2 signaling pathways downstream of RANK, followed by decreased expression of nuclear factor of activated T cells c1. Notably, OC formation was efficiently restored by addition of adenosine diphosphate, a P2Y12 agonist, as well as by addition of CysLT. Furthermore, similar to montelukast, P2Y12 blockade by a pharmacological inhibitor or siRNAs suppressed OC differentiation. These data indicate the involvement of the P2Y12 receptor in the inhibitory effect of montelukast on osteoclastogenesis. Invivo, montelukast significantly inhibited inflammation‑induced osteoclastogenesis in the calvarial model. Montelukast also served a protective role in a murine ovariectomy (OVX)‑ and unloading‑induced bone loss model. Altogether, these results confirmed that the CysLTR1 antagonist exerted an inhibitory effect on OC formation invitro and invivo. It may be useful for the treatment of bone diseases associated with excessive bone resorption.