Cysteinyl Leukotriene Receptor Research Articles

Roles of cysteinyl leukotrienes and their receptors in immune cell-related functions.

The cysteinyl leukotrienes (cys-LTs), leukotriene C4, (LTC4), LTD4, and LTE4, are lipid mediators of inflammation. LTC4 is the only intracellularly synthesized cys-LT through the 5-lipoxygenase and LTC4 synthase pathway and after transport is metabolized to LTD4 and LTE4 by specific extracellular peptidases. Each cys-LT has a preferred functional receptor in vivo; LTD4 to the type 1 cys-LT receptor (CysLT1R), LTC4 to CysLT2R, and LTE4 to CysLT3R (OXGR1 or GPR99). Recent studies in mouse models revealed that there are multiple regulatory mechanisms for these receptor functions and each receptor plays a distinct role as observed in different mouse models of inflammation and immune responses. This review focuses on the integrated host responses to the cys-LT/CysLTR pathway composed of sequential ligands with preferred receptors as seen from mouse models. It also discusses potential therapeutic targets for LTC4 synthase, CysLT2R, and CysLT3R.

Curcumin prevents cigarette smoke extract induced cognitive impairment.

Curcumin is a major phytochemical constituent in Curcuma longa, an herbaceous perennial plant of Zingiberaceae family, which exhibits anti-oxidant, anti-inflammatory and immunomodulatory properties. Here, we studied the therapeutic action of curcumin against CSE induced cognitive impairment in zebrafish. Montelukast (20 mg/kg), a cysteinyl-leukotriene receptor blocker was used as a reference drug. CSE exposure induced biochemical changes revealed that raise the brain acetylcholinesterase activity and lipid peroxidative products; and decrease the reduced glutathione levels in brain samples. Curcumin also protected against CSE induced neurocognitive impairment. These data suggest that curcumin can serve as a phytochemical constituent against CSE induced neurocognitive impairment.

Cysteine leukotriene receptors type 2 (CyLTR2 M01 V) gene polymorphism and its role in Iraqi asthmatic patients

Background: Asthma is currently understood to be a fairly common but complicated chronic respiratory disease with multiple etiologies. Polymorphism in the CysLTR2 gene resulting in a single amino acid substitution, M201V (i.e. amino acid methionine changed for valine at the 201 position of CysLTR2 protein). Objectives: The aims of this study included analyzing of polymorphism in CyLTR2 M01 V genes and determined whether there is an interaction and association between these polymorphisms and some parameter (total IgE, IL-5, Eosinophil) for asthma development in Iraqi asthmatic patients. Methods: 100 patients with asthma with ages ranged between (15- 50) years were taken from (Al-Hussein Medical City/Kerbala). Control group consisted of 60 healthy people who were free from signs and symptoms of Asthma who matched in age and gender with patients, and had no history for any asthma problem. Total IgE and IL-5 Euroimmun /Ggermen, Peprotech UK respectively) was studied using the enzyme-linked immunosorbent assay (ELISA) method and automated blood cell counter (Sysmex XT-200i)for eosinophil counts, the CyLTR2 M01 V also studied by using RFLP PCR . T-test and ANOVA and Pearson correlation used to analyze results by using SPSS version 20. P-value = 0.05 was considered significant. Results: Total IgE, IL-5 levels and Eosinophil counts were increased significantly (p< 0.05) in patients compared with control group. Also there were show significant abnormality and complication when compared with control groups, there Regarding to CyLTR2 M01 V gene polymorphism were done by RFLP PCR there is no statistical difference between control and asthmatic patients. also there are a statistically significant difference in serum IgE . serum IL-5 and blood eosinophil between each two groups depending on polymorphism in cysteine leukotriene receptor 2 (CyLTR2 M01 V). Conclusion: there are a significantly correlation between total IgE, IL-5 levels and eosinophil counts and polymorphism in cysteine leukotriene receptor 2 (CyLTR2 M01 V)in asthmatic patients . but CysLTR1 927A/T gene polymorphism no show statistical difference between control and asthmatic patients.

Cysteinyl leukotriene receptor type 1 (CysLT1R) antagonist zafirlukast protects against TNF-α-induced endothelial inflammation

Endothelial dysfunction induced by chronic inflammation has been considered one of the most important mechanisms behind a variety of cardiovascular diseases. Extensive efforts have been made in past decades to explore the underlying mechanisms of endothelial dysfunction and to develop new therapeutic agents for the treatment of cardiovascular diseases. Zafirlukast, a selective antagonist of CysLT receptor 1 (CysLT1R), has been licensed by the U.S. Food and Drug Administration (FDA) for the treatment of asthma. In this study, we found that zafirlukast possesses beneficial protective effects on endothelial cells from TNF-α-induced inflammatory response and injury. Our results indicate that TNF-α treatment induces CysLT1R expression. The addition of zafirlukast to culture media suppressed TNF-α-induced expression of endothelial vascular adhesion molecules, such as ICAM-1, VCAM-1, and induction of cytokines, including IL-1β, IL-6, and IL-8. Zafirlukast also ameliorated production of reactive oxygen species (ROS) and adhesion of monocytes to endothelial cells induced by TNF-α. Mechanistically, we demonstrate that zafirlukast suppresses MAPK kinase p38 and NF-κB activation to inhibit inflammatory mediators. Collectively, our findings provide insights into the mechanisms of a potential therapeutic strategy for endothelial dysfunction-related diseases and shed light on the possible application of zafirlukast in cardiovascular diseases such as atherosclerosis.

Characterization of cysteinyl leukotriene-related receptors and their interactions in a mouse model of asthma

Identification of the characterization of cysteinyl leukotrienes receptor (CysLTRs) could facilitate our understanding of these receptors’ role in asthma. We aimed to investigate the localization and interactions of CysLTRs using a mouse model of asthma. BALB/c mice were administered ovalbumin (OVA) to induce allergic asthma. Some mice were administered the antagonists of CysLTR1, CysLTR2, and purinergic receptor P2Y12 (P2Y12R) (montelukast, HAMI 3379 and clopidogrel, respectively). The expression levels of CysLTR1, CysLTR2, and P2Y12R on lung tissues and inflammatory cells were evaluated by western blot, flow cytometry, and immunochemistry. CysLTR1 and P2Y12R were significantly up-regulated in lung tissues (P < 0.05 for each) from mouse after being sensitized and challenged with OVA (OVA/OVA). The ratio of CysLTR1: CysLTR2: P2Y12R in lungs of negative control (NC) mice was shifted from 1:0.43:0.35 to 1:0.65:1.34 in OVA/OVA mice. Montelukast significantly diminished the up-regulation of CysLTR1, CysLTR2, and P2Y12R (P < 0.05 for each), while the effects of HAMI 3379 and clopidogrel were predominant on the expression of CysLTR2 and P2Y12R, respectively. Montelukast predominantly diminished the cell count, while clopidogrel potently inhibited the release of interleukin (IL)-4, IL-5, and IL-13. Our study demonstrated the interactions between CysLTRs, thereby highlighting the potential synergistic effects of CysLTR antagonists in asthma treatment.

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.

Influence of leukotriene receptor antagonist on contractile activity of the porcine uterine smooth muscle in the luteal phase and in early pregnancy.

This study analysed the influence of montelukast (MON; 10-8 - 10-4 M), a cysteinyl leukotriene receptor 1 (CysLTR1) antagonist, on the contractility of the porcine uterine smooth muscle in the luteal phase of the oesterous cycle (n=8) and in early pregnancy (n=8). Stimulation of uterine strips in the luteal phase with MON has been shown to significantly reduce the amplitude of con- tractions, but not to affect the tension or frequency of contractions. A statistically significant tension increase and decrease in the frequency and amplitude of contractions was observed in pigs in early pregnancy. This suggests that MON has a different effect on the parameters under study in cyclic and pregnant pigs.

Selective Optimization of Pranlukast to Farnesoid X Receptor Modulators.

Selective optimization of side activities (SOSA) offers an alternative entry to early drug discovery and may provide rapid access to bioactive new chemical entities with desirable properties. SOSA aims to reverse a drug's side activities through structural modification and to design out the drug's original main action. We identified a moderate side activity for the cysteinyl leukotriene receptor 1 (CysLT1 R) antagonist pranlukast on the farnesoid X receptor (FXR). Systematic structural modification of the drug allowed remarkable optimization of its partial FXR agonism to sub-nanonmolar potency. The resulting FXR modulators lack any activity on CysLT1 R and are characterized by high selectivity, high metabolic stability, and low toxicity. With their favorable in vitro profile, these SOSA-derived FXR modulators constitute a new FXR ligand chemotype that appears suitable for further preclinical evaluation.

IL-33 Upregulates Cysteinyl Leukotriene Receptor Type 1 Expression in Human Peripheral Blood CD4+ T Lymphocytes.

IL-33 and cysteinyl leukotrienes (cysLTs) are key components of asthma pathogenesis, and both contribute to the initiation and maintenance of the type 2 inflammatory environment. However, little is known about the potential interactions between the two mediators. In this work, we aimed at studying the regulation of expression of the cysLT receptors CysLT1 and CysLT2 by IL-33 in human PBLs. Our results show that the IL-33/ST2L axis increases CysLT1 but not CysLT2 expression in a concentration- and time-dependent manner in PBLs. IL-33-induced CysLT1 upregulation was observed at the protein but not at the mRNA level and was accompanied by an increase in LTD4-induced calcium mobilization and migration of CD4+ T lymphocytes. We also show that purified naive CD4+ T lymphocytes expressed ST2L and responded to IL-33 in the absence of Ag or TCR stimulation, suggesting a mechanism independent of Ag presentation. These results contribute to expanding our knowledge in the field of IL-33 by proposing a new mode of action of the cytokine on T cells and by extending its role to the regulation of naive T cell trafficking, therefore reinforcing its interest as a potential therapeutic target for the treatment of asthma.

Cysteinyl leukotriene 1 receptor expression in nasal polyps.

Cysteinyl leukotrienes (CysLTs) have been implicated in the pathogenesis of chronic rhinosinusitis (CRS). This study was undertaken to better understand the role of CysLTs in the development of CRS through 1). assessment of the pattern of expression of CysLT1 receptor in nasal polyps from patients with CRS and 2). correlation of expression of CysLT1 receptor with clinical features. Expression of CysLT1 receptor was evaluated immunohistochemically in nasal polyps from 20 patients with CRS and nasal mucosa from 10 control subject undergoing plastic surgery of the nose. Patients with CRS showed significantly higher expression of CysLT1 receptor as compared with the control group (p&lt;0.05). The expression of CysLT1 receptor in sub-epithelial inflammatory infiltrates tended to be higher in patients with CRS and allergy as compared with patients with CRS but without allergy (p=0.07). In particular, the expression of CysLT1 receptor in sub-epithelial inflammatory infiltrates was significantly greater in 3 patients with CRS and drug allergy as compared with patients with CRS but without drug allergy (p=0.03). Increased expression of CysLT1 receptor in inflamed mucosa of nasal polyps in patients with allergy might suggest particular role of CysLTs in the pathogenesis of nasal polyps in this group of patients.

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.

Cysteinyl leukotriene receptor 1 (cysLT1R) regulates osteoclast differentiation and bone resorption

Excessive bone resorption induced by abnormal osteoclast differentiation has been associated with bone microstructure damage and bone-associated disorders, including osteoporosis. Here, we investigated the physiological roles of the type 1 cysteinyl leukotriene receptor (cysLTR-1) and the pharmacological functions of the specific cysLTR-1 antagonist montelukast on M-CSF- and RANKL-induced osteoclast differentiation. We showed that cysLTR-1 but not cysLTR-2 is expressed in osteoclast precursor cells: mouse bone marrow-derived macrophages (BMMs). We also found that treatment with M-CSF and RANKL significantly increased expression of cysLTR-1. Overexpression of cysLTR-1 promoted osteoclast differentiation of BMMs by increasing NFATc1 and TRAP. In contrast, treatment with montelukast prevented M-CSF- and RANKL-induced osteoclast differentiation of BMMs. Mechanically, our findings demonstrate that montelukast treatment attenuated activation of the ERK1/2, p38, JNK and NF-κB signalling pathways. Additionally, we reported that montelukast treatment ameliorated the generation of ROS and calcium signalling. Importantly, the co-immunoprecipitation assay displayed that montelukast treatment prevented the interaction of RANK and TRAF6. Finally, in vivo experiments indicated that montelukast rescued the reduction of bone volume as well as trabecular number in an ovariectomy mouse model.

GPR17 mediates ischemia-like neuronal injury via microglial activation.

GPR17 is a G (i)-coupled dual receptor, linked to P2Y and CysLT receptors stimulated by uracil nucleotides and cysteinyl leukotrienes, respectively. Recent evidence has demonstrated that GPR17 inhibition ameliorates the progression of cerebral ischemic injury by regulating neuronal death and microglial activation. The present study aimed to assess the detailed regulatory roles of this receptor in oxygen-glucose deprivation/recovery (OGD/R)-induced ischemia-like injury in vitro and explore the underlying mechanism. The results demonstrated that OGD/R induced ischemic neuronal injury and microglial activation, including enhanced phagocytosis and increased inflammatory cytokine release in neuron‑glial mixed cultures of cortical cells. GPR17 upregulation during OGD/R was spatially and temporally correlated with neuronal injury and microglial activation. In addition, GPR17 knockdown inhibited OGD/R-induced responses in neuron-glial mixed cultures. GPR17 knockdown also attenuated cell injury induced by the agonist leukotriene D4 (LTD4) or uridine 5′-diphosphate (UDP) in neuron-glial mixed cultures. However, GPR17 knockdown did not affect OGD/R-induced ischemic neuronal injury in primary cultures of neurons. In primary astrocyte cultures, neither GPR17 nor OGD/R induced injury. By contrast, GPR17 knockdown ameliorated OGD/R-induced microglial activation, boosting phagocytosis and inflammatory cytokine release in primary microglia cultures. Finally, the results demonstrated that the conditioned medium of microglia pretreated with OGD/R induced neuronal death, and the neuronal injury was significantly inhibited by GPR17 knockdown. These findings suggested that GPR17 may mediate ischemia-like neuronal injury and microglial activation in vitro; however, the protective effects on ischemic neuronal injury might depend upon microglial activation. Whether GPR17 regulates neuronal injury mediated by oligodendrocyte linkage remains to be investigated.

BLTR1 in Monocytes Emerges as a Therapeutic Target For Vascular Inflammation With a Subsequent Intimal Hyperplasia in a Murine Wire-Injured Femoral Artery

Given the importance of high-mobility group box 1 (HMGB1) and 5-lipoxygenase (5-LO) signaling in vascular inflammation, we investigated the role of leukotriene signaling in monocytes on monocyte-to-macrophage differentiation (MMD) induced by HMGB1, and on vascular inflammation and subsequent intimal hyperplasia in a mouse model of wire-injured femoral artery. In cultured primary bone marrow-derived cells (BMDCs) stimulated with HMGB1, the number of cells with macrophage-like morphology was markedly increased in association with an increased expression of CD11b/Mac-1, which were attenuated in cells pre-treated with Zileuton, a 5-LO inhibitor as well as in 5-LO-deficient BMDCs. Of various leukotriene receptor inhibitors examined, which included leukotriene B4 receptors (BLTRs) and cysteinyl leukotriene receptors (cysLTRs), the BLTR1 inhibitor (U75302) exclusively suppressed MMD induction by HMGB1. The importance of BLTR1 in HMGB1-induced MMD was also observed in BMDCs isolated from BLTR1-deficient mice and BMDCs transfected with BLTR1 siRNA. Although leukotriene B4 (LTB4) had minimal direct effects on MMD in control and 5-LO-deficient BMDCs, MMD attenuation by HMGB1 in 5-LO-deficient BMDCs was significantly reversed by exogenous LTB4, but not in BLTR1-deficient BMDCs, suggesting that LTB4/BLTR1-mediated priming of monocytes is a prerequisite of HMGB1-induced MMD. In vivo, both macrophage infiltration and intimal hyperplasia in our wire-injured femoral artery were markedly attenuated in BLTR1-deficient mice as compared with wild-type controls, but these effects were reversed in BLTR1-deficient mice transplanted with monocytes from control mice. These results suggest that BLTR1 in monocytes is a pivotal player in MMD with subsequent macrophage infiltration into neointima, leading to vascular remodeling after vascular injury.

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.

Evaluation of oncogenic cysteinyl leukotriene receptor 2 as a therapeutic target for uveal melanoma.

Uveal melanoma is a rare, but deadly, form of eye cancer that arises from melanocytes within the uveal tract. Although advances have emerged in treatment of the primary tumour, patients are still faced with vision loss, eye enucleation and lethal metastatic spread of the disease. Approximately 50% of uveal melanoma patients develop metastases, which occur most frequently in the liver. Metastatic patients encounter an extremely poor prognosis; as few as 8% survive beyond 2years. Understanding of the genetic underpinnings of this fatal disease evolved in recent years with the identification of new oncogenic mutations that drive uveal melanoma pathogenesis. Despite this progress, the lack of successful therapies or a proven standard-of-care for uveal melanoma highlights the need for new targeted therapies. This review focuses on the recently identified CYSLTR2 oncogenic mutation in uveal melanoma. Here, we evaluate the current status of uveal melanoma and investigate how to better understand the role of this CYSLTR2 mutation in the disease and implications for patients harbouring this mutation.

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.

Abstract 13: Anti-angiogenic action of leukotriene-C4induced 15-hydroxyprostaglandin dehydrogenase in colon cancer cells is a TNF-α dependent phenomenon

Abstract Colorectal cancer (CRC) is one of the leading causes of cancer-related deaths worldwide. Cyclooxygenase-2 (COX-2), which plays a key role in the biosynthesis of prostaglandin E2 (PGE2), is often up-regulated in CRC and in other types of cancer. PGE2 induces angiogenesis and tumor cell survival, proliferation and migration. The tumor suppressor 15-hydroxyprostaglandin dehydrogenase (15-PGDH) is a key enzyme in PGE2 catabolism, converting it into its inactive metabolite 15-keto-PGE2 and is often down-regulated in cancer. Interesting enough, CRC patients expressing high levels of Cysteinyl leukotriene receptor 2 (CysLTR2) have a good prognosis and therefore, we investigated a potential link between CysLTR2-signaling and the tumor suppressor 15-PGDH in colon cancer cells. TNF-α is considered as the main regulators of COX-2 and mPGES-1 that contribute to the increased synthesis of PGE2, which is inhibited by overexpressed 15-PGDH. Level of the pro-tumorigenic PGE2 are increased in CRC, previously attributed to increased production via TNF-α mediated COX-2 up-regulation but more recently attributed to decreased catabolism due to down-regulation of 15-PGDH. Elevation of 15-PGDH expression by leukotriene C4 (LTC4), a CysLTR2 ligand, exhibited anti-tumor activity in colon cancer cells with significant phosphorylation of β-catenin and down-regulation of anti-apoptotic marker Bcl-2 with concurrent activation of CASPASE-3 expression. We also observed a dramatic down-regulation of TNF-α on mRNA level and NF-κβ on both mRNA as well as protein level with LTC4 induced 15-PGDH in a TNF-α dependent manner. Moreover, TNF-α regulated anti-angiogenic action of 15-PGDH in HT-29 and Caco-2 colon cancer cells by depleting the mRNA level of MMP-2 and MMP-9 and protein level of VEGFR-1. Furthermore, our preliminary observation also suggested disrupted tube formation in HUVEC with LTC4 induced 15-PGDH which is mediated by TNF-α. Hence, restoration of 15-PGDH expression through CysLTR2-signaling promotes the anti-angiogenic action against colon cancer cells, indicating an anti-tumor as well as the anti-metastatic efficacy of CysLTR2-signaling. Citation Format: Shakti R. Satapathy, Anita Sjölander. Anti-angiogenic action of leukotriene-C4induced 15-hydroxyprostaglandin dehydrogenase in colon cancer cells is a TNF-α dependent phenomenon [abstract]. In: Proceedings of the American Association for Cancer Research Annual Meeting 2018; 2018 Apr 14-18; Chicago, IL. Philadelphia (PA): AACR; Cancer Res 2018;78(13 Suppl):Abstract nr 13.

Cysteinyl-leukotriene pathway as a new therapeutic target for the treatment of atherosclerosis related to obstructive sleep apnea syndrome

AimsObstructive sleep apnea (OSA) characterized by nocturnal intermittent hypoxia (IH) is associated with atherosclerosis and cysteinyl-leukotrienes (CysLT) pathway activation. We aimed to identify the determinants of CysLT pathway activation and the role of CysLT in OSA-related atherosclerosis. Methods and resultsDeterminants of the urinary excretion of LTE4 (U-LTE4) including history of cardiovascular events, polysomnographic and biological parameters were studied in a cohort of 170 OSA patients and 29 controls, and in a subgroup of OSA patients free of cardiovascular event (n = 136). Mechanisms linking IH, the CysLT pathway and atherogenesis were investigated in Apolipoprotein E deficient (ApoE−/−) mice exposed to 8-week IH.In the whole cohort, U-LTE4 was independently influenced by age, minimal oxygen saturation, and a history of cardiovascular events, and correlated significantly with intima-media thickness. In the subgroup of OSA patients free of cardiovascular event, increased U-LTE4 was increased compared to controls and independently related to hypoxia severity and traditional risk factors aggregated in the 10-year cardiovascular risk score of European Society of Cardiology. In IH mice, atherosclerosis lesion size and mRNA levels of 5-lipoxygenase, 5-lipoxygenase activating protein (FLAP) and CysLT1 receptor were significantly increased. This transcriptional activation was associated with the binding of HIF-1 to the FLAP promoter and was strongly associated with atherosclerosis lesion size. CysLT1 receptor antagonism (montelukast) significantly reduced atherosclerosis progression in IH mice. ConclusionsIH-related CysLT pathway activation contributes to OSA-induced atherogenesis. In the era of personalized medicine, U-LTE4 may be a useful biomarker to identify OSA patients for whom CysLT1 blockade could represent a new therapeutic avenue for reducing cardiovascular risk.

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.