OBJECTIVE: To explore the expression patterns, prognostic implications, and biological role of leukotriene B4 receptor (LTB4R) in patients with acute myeloid leukemia (AML). METHODS: We collected the data of mRNA expression levels and clinical information of patients with AML from The Cancer Genome Atlas (TCGA) and Gene Expression Omnibus (GEO) database for mRNA expression analyses, survival analyses, Cox regression analyses and correlation analyses using R studio to assess the expression patterns and prognostic value of LTB4R. The correlation of LTB4R expression levels with clinical characteristics of the patients were analyzed using UALCAN. The co-expressed genes LTB4R were screened from Linkedomics and subjected to functional enrichment analysis. A protein-protein interaction network was constructed using STRING. GSEA analyses of the differentially expressed genes (DEGs) were performed based on datasets from TCGA-LAML stratified by LTB4R expression level. We also collected peripheral blood mononuclear cells (PBMCs) from AML patients and healthy donors for examination of the mRNA expression levels of LTB4R and immune checkpoint genes using qRT-PCR. We also examined serum LTB4R protein levels in the patients using ELISA. RESULTS: The mRNA expression level of LTB4R was significantly increased in AML patients (4.898±1.220 vs 2.252±0.215, P < 0.001), and an elevated LTB4R expression level was correlated with a poor overall survival (OS) of the patients (P=0.004, HR=1.74). LTB4R was identified as an independent prognostic factor for OS (P=0.019, HR=1.66) and was associated with FAB subtypes, cytogenetic risk, karyotype abnormalities and NPM1 mutations. The co- expressed genes of LTB4R were enriched in the functional pathways closely associated with AML leukemogenesis, including neutrophil inflammation, lymphocyte activation, signal transduction, and metabolism. The DEGs were enriched in differentiation, activation of immune cells, and cytokine signaling. Examination of the clinical serum samples also demonstrated significantly increased expressions of LTB4R mRNA (P=0.044) and protein (P=0.008) in AML patients, and LTB4R mRNA expression was positively correlated with the expression of the immune checkpoint HAVCR2 (r= 0.466, P=0.040). CONCLUSION LTB4R can serve as a novel biomarker and independent prognostic indicator of AML and its expression patterns provide insights into the crosstalk of leukemogenesis signaling pathways involving tumor immunity and metabolism.
Humans ; Leukemia, Myeloid, Acute/metabolism* ; Leukocytes, Mononuclear/metabolism* ; Prognosis ; RNA, Messenger/metabolism* ; Receptors, Leukotriene B4/genetics*

OBJECTIVE: : To investigate the effects of cysteinyl leukotrienes receptor (CysLTR) antagonists on global cerebral ischemia/reperfusion (CI/R) injury in gerbils, and to explore its mechanism. METHODS: : Totally 40 gerbils weighting 45-65 g were randomized into sham, saline, Pranlukast and HAMI 3379 groups with 10 animals in each. The CI/R model was established in gerbils by bilateral common carotid occlusion for 10 min followed by reperfusion. After ischemia, the CysLTR antagonists Pranlukast (0.1 mg/kg) and HAMI 3379 (0.1 mg/kg) were injected intraperitoneally for 5 consecutive days in the last two groups,while the former two groups were injected with saline only (10 mL/kg). After 24 h or 14 d reperfusion, neurological deficit score was evaluated and the behavioral dysfunction was assessed, respectively. And 14 d after reperfusion, the neuron morphology of cerebral cortex was observed in brain sections stained with Cresyl violet. In addition, the Iba-1 (microgila) and GFAP (astrocyte) positive cells in cerebral cortex were observed by using immunohistochemitry method. RESULTS: : CI/R models were successfully established in 21 out of 30 gerbils with 7 in saline group, 6 in Pranlukast group, and 8 in HAMI 3379 group. Compared with saline group, Pranlukast and HAMI 3379 significantly attenuated neurological deficits, improved the behavioral function 24 h after reperfusion(all <0.01); Pranlukast and HAMI 3379 also significantly improved the behavioral function 14 days after reperfusion(<0.05 or <0.01). Compared with saline group, the neurological symptom scores in Pranlukast and HAMI 3379 groups presented a trend of amelioration 14 d after reperfusion, but it was not significant(>0.05). In addition, Pranlukast and HAMI 3379 also inhibited the neuron loss and injury, suppressed microgila and astrocyte activation 14 d after reperfusion(all <0.01). CONCLUSIONS : CysLTR antagonists Pranlukast and HAMI 3379 have long-term neuroprotective effect on chronic brain injury induced by global cerebral ischemia/reperfusion in gerbils.
Animals ; Behavior, Animal ; drug effects ; Brain Injury, Chronic ; drug therapy ; Brain Ischemia ; Gerbillinae ; Leukotriene Antagonists ; pharmacology ; therapeutic use ; Neuroprotective Agents ; pharmacology ; therapeutic use ; Random Allocation ; Receptors, Leukotriene ; metabolism ; Reperfusion Injury ; drug therapy

OBJECTIVE: : To determine the effects of cysteinyl leukotriene receptors (CysLTR and CysLTR) on phagocytosis of mouse BV2 microglial cells. METHODS: : BV2 cells were stimulated with microglial activators lipopolysaccharide (LPS) or CysLT receptor agonists LTD. The phagocytosis of BV2 cells was observed by immunofluorescence analysis and flow cytometry. The intracellular distributions of CysLTR and CysLTR in BV2 cells were examined with immunofluorescence staining. RESULTS: : Both LPS and LTD could significantly enhance the phagocytosis of BV2 cells, and such effect could be inhibited by CysLTR selective antagonist Montelukast and CysLTR selective antagonist HAMI 3379. The activation of BV2 cells induced by LTD or LPS resulted in changes in intracellular distributions of CysLTR and CysLTR. CysLTR and CysLTR was co-localization with a similar distribution. CONCLUSIONS : CysLTR and CysLTR regulate the phagocytosis of mouse BV2 microglial cells with a synergistic effect.
Acetates ; pharmacology ; Animals ; Cell Line ; Cyclohexanecarboxylic Acids ; pharmacology ; Lipopolysaccharides ; pharmacology ; Mice ; Microglia ; cytology ; Phagocytosis ; drug effects ; Phthalic Acids ; pharmacology ; Protein Binding ; drug effects ; Quinolines ; pharmacology ; Receptors, Leukotriene ; agonists ; metabolism

OBJECTIVETo investigate expression of the cysteinyl leukotriene receptor (CysLT1R) in hepatocellular carcinoma (HCC) tissues and determine its clinical significance.

METHODSCancerous and paraneoplastic liver tissues were collected from 30 patients with HCC and from 12 patients with liver hemangioma patients (controls). Real-time PCR and immunohistochemistry were used to evaluate the expression of CysLT1R in these tissues and assess the relationship with clinical pathological features. T-test,?Fisher's exact test and Kaplan-Meier survival analysis were used for statistical analysis.

RESULTSThe expression of CysLT1R in adjacent liver tissues (100%) was higher than that in the HCC (43.33%, P = 0.000) and normal liver tissues (41.67%, P = 0.000). The level of CysLT1R mRNA was also higher in paraneoplastic liver tissues (0.0339+/-0.0221) than in the paired HCC tissues (0.0127+/-0.0116, t = 2.911, P = 0.008) and normal liver tissues (0.0154+/-0.0123, t = -2.310, P = 0.033). There was no difference between the levels in HCC and normal liver tissues (P more than 0.05). Higher level of CysLT1R mRNA, higher level of serum alpha-fetoprotein, and higher tumor stage (III-IV) were associated with poor prognosis (respectively 4.372, P = 0.037; 24.187, P = 0.000; 8.75, P = 0.003). However, no evident relationship between the expression of CysLT1R and other clinical features was observed. Conclusions Overexpression of CysLT1R may contribute to the occurrence and progression of HCC.

Carcinoma, Hepatocellular ; diagnosis ; metabolism ; Case-Control Studies ; Disease Progression ; Humans ; Immunohistochemistry ; Kaplan-Meier Estimate ; Liver Neoplasms ; diagnosis ; metabolism ; Neoplasm Staging ; Prognosis ; RNA, Messenger ; metabolism ; Real-Time Polymerase Chain Reaction ; Receptors, Leukotriene ; metabolism ; alpha-Fetoproteins ; metabolism

OBJECTIVETo examine the expression of cysteinyl leukotriene receptor-1 (CysLTR-1) and cysteinyl leukotriene receptor-2 (CysLTR-2) in the adenoid tissues from children with adenoid hypertrophy (AH) and to explore the role of leukotrienes in the pathogenesis of AH.

METHODSSixty children with AH who were treated by adenoidectomy and/or tonsillectomy were classified into two groups: simple AH and AH plus allergic rhinitis (n=30 each). Twenty children who underwent tonsillectomy due to recurrent purulent tonsillitis were selected as the control group. The expression of CysLTR-1 and CysLTR-2 in the excised tonsil and/or adenoid tissues was determined by immunofluorescence histochemical labeling and integrated optical density measurement.

RESULTSThe expression of CysLTR-1 and CysLTR-2 in the adenoid and tonsil tissues increased significantly in both the simple AH group and AH plus allergic rhinitis group compared with the control group (P<0.01). The expression of CysLTR-1 and CysLTR-2 in the AH plus allergic rhinitis group increased more significantly compared with the simple AH group (P<0.01).

CONCLUSIONSCysLTR-1 and CysLTR-2 are highly expressed in the adenoid tissues from children with AH, suggesting that leukotrienes are involved in the pathogenesis of AH.

Adenoids ; chemistry ; pathology ; Adolescent ; Child ; Child, Preschool ; Female ; Fluorescent Antibody Technique ; Humans ; Hypertrophy ; Male ; Receptors, Leukotriene ; analysis ; physiology ; Rhinitis, Allergic ; metabolism

Endotoxic responses to bacterial lipopolysaccharide (LPS) are triggered by Toll-like receptor 4 (TLR4) and involve the production of inflammatory mediators, including interleukin-6 (IL-6), by macrophages. The detailed mechanism of IL-6 production by macrophages in response to LPS has remained unclear, however. We now show that LPS induces IL-6 synthesis in mouse peritoneal macrophages via the leukotriene B4 receptor BLT2. Our results suggest that TLR4-MyD88 signaling functions upstream of BLT2 and that the generation of reactive oxygen species (ROS) by NADPH oxidase 1 (Nox1) and consequent activation of the transcription factor nuclear factor (NF)-kappaB function downstream of BLT2 in this response. These results suggest that a TLR4-MyD88-BLT2-Nox1-ROS-NF-kappaB pathway contributes to the synthesis of IL-6 in LPS-stimulated mouse macrophages.
Animals ; Cell Line ; Interleukin-6/*biosynthesis ; Leukotriene B4/metabolism ; Ligands ; Lipopolysaccharides/immunology ; Macrophages/immunology/*metabolism ; Macrophages, Peritoneal/immunology/metabolism ; Mice ; Myeloid Differentiation Factor 88/*metabolism ; NADH, NADPH Oxidoreductases/metabolism ; NF-kappa B/metabolism ; Reactive Oxygen Species/metabolism ; Receptors, Leukotriene B4/*metabolism ; Signal Transduction

OBJECTIVETo investigate the effect of montelukast on the expression of sensory neuropeptide (neurokinin-1) receptor (NK1R) in young asthmatic rats with airway remodeling.

METHODSTwenty-four Sprague-Dawley rats were randomly divided into control group (n=8), asthma (n=8), and montelukast groups (n=8). A rat model of asthma was induced by ovalbumin (OVA) inhalation. Normal saline was used instead of sensitizing solution and 1% OVA in the control group. Each rat in the montelukast group was given montelukast (15 mg/kg) by gavage 2 h before OVA inhalation. All rats received their respective treatments for 8 weeks. Immunohistochemistry, real-time PCR and Western blot were used to measure the mRNA and protein expression levels of NK1R in asthmatic airway remolding and to evaluate the effect of montelukast on NK1R expression.

RESULTSThe asthma group showed significantly higher mRNA and protein expression levels of NK1R than the control group (P<0.01). The mRNA and protein expression levels of NK1R in the montelukast group were significantly lower than in the asthma group (P<0.05), but significantly higher than in the control group (P<0.01).

CONCLUSIONSRats with induced asthma have upregulated NK1R expression in the airway, and montelukast can downregulate NK1R expression during airway remodeling.

Acetates ; pharmacology ; Airway Remodeling ; drug effects ; Animals ; Anti-Asthmatic Agents ; pharmacology ; Asthma ; drug therapy ; metabolism ; Female ; Leukotriene Antagonists ; pharmacology ; Quinolines ; pharmacology ; RNA, Messenger ; analysis ; Rats ; Rats, Sprague-Dawley ; Receptors, Neurokinin-1 ; analysis ; genetics

OBJECTIVETo investigate the effects of CysLT receptor agonist leukotriene D4(LTD4) and antagonists on activation of microglia BV2 cells.

METHODSThe expression of CysLT1 and CysLT2 protein was determined by Western blotting and immunostaining in microglia BV2 cells. BV2 cells were pretreated with or without CysLT1 receptor selective antagonist montelukast, CysLT2 receptor selective antagonist HAMI 3379, or CysLT1/CysLT2 receptor dual antagonist BAY u9773 for 30 min, then the cells were treated with LTD4 for 24 h. Cell viability was detected by MTT reduction assay. Phagocytosis and mRNA expression of IL-6 were determined by fluorescent bead tracking and RT-PCR, respectively.

RESULTSIn BV2 cells, LTD4 did not affect proliferation but significantly enhanced phagocytosis and increased IL-6 mRNA expression in a concentration-dependent manner. LTD4 at 100 nmol/L induced a 1.4-fold increase of phagocytic index and a 2-fold up-regulation of IL-6 mRNA expression (P<0.01). HAMI 3379 and BAY u9773 (100 nmol/L) further increased LTD4-induced phagocytosis; BAY u9773 and montelukast decreased LTD4-induced IL-6 mRNA expression, while HAMI 3379 had no effect on that.

CONCLUSIONLTD4 activates BV2 cells in vitro and enhances IL-6 mRNA expression mediated by CysLT1 receptor, LTD4 induces phagocytosis which might be negatively regulated by CysLT2 receptor in BV2 cells.

Acetates ; pharmacology ; Cell Line ; Cell Proliferation ; Cyclohexanecarboxylic Acids ; pharmacology ; Humans ; Interleukin-6 ; metabolism ; Leukotriene Antagonists ; pharmacology ; Leukotriene D4 ; pharmacology ; Microglia ; cytology ; metabolism ; Phagocytosis ; Phthalic Acids ; pharmacology ; Quinolines ; pharmacology ; Receptors, Leukotriene ; metabolism ; SRS-A ; analogs & derivatives ; pharmacology

OBJECTIVETo examine the spatiotemporal profiles and localization of CysLT1R, CysLT2R and GPR17 in mice with 1-methyl-4-phenyl-1, 2, 3, 6-tetrahydropyridine (MPTP)-induced Parkinson disease (PD).

METHODSPD model was induced by subcutaneous injection of MPTP (25 mg/kg) for 5 d in adult male C57BL/6 mice. At d10 after MPTP injection, the expression and cellular localization of CysLT1R, CysLT2R and GPR17 in the substantia nigra were detected by immunohistochemistry and immunofluorescence.

RESULTSCysLT1R, CysLT22 and GPR17 were normally localized in TH-positive dopaminergic neurons and microglia, while CysLT2R was also expressed in astrocytes. In dopaminergic neurons, approximately 91% co-expressed GPR17, 77% co-expressed CysLT1R and 52% co-expressed CysLT2R. Compared with the control group, TH-positive cells in the substantia nigra were significantly reduced in PD mice. CysLT1R, CysLT2R and GPR17-positive cells were significantly reduced; and CysLT1R, CysLT2R, GPR17-positive dopaminergic neurons were also significantly reduced in the PD group. In the striatum, both CysLT1R and GPR17 were normally expressed in neurons; whereas CysLT2R was expressed in astrocytes. In PD striatum, CysLT1R and GPR17-positive cells were decreased, but CysLT2R expression was significantly increased which mainly expressed in the proliferating astrocytes.

CONCLUSIONCysLT1R, CysLT2R and GPR17 may be involved in the MPTP-induced PD damage in mice.

Animals ; Brain ; metabolism ; Disease Models, Animal ; Male ; Mice ; Mice, Inbred C57BL ; Nerve Tissue Proteins ; metabolism ; Parkinson Disease ; metabolism ; Receptors, G-Protein-Coupled ; metabolism ; Receptors, Leukotriene ; metabolism

12(S)-Hydroxyheptadeca-5Z,8E,10E-trienoic acid (12-HHT) is an enzymatic product of prostaglandin H2 (PGH2) derived from cyclooxygenase (COX)-mediated arachidonic acid metabolism. Despite the high level of 12-HHT present in tissues and bodily fluids, its precise function remains largely unknown. In this study, we found that 12-HHT treatment in HaCaT cells remarkably down-regulated the ultraviolet B (UVB) irradiation-induced synthesis of interleukin-6 (IL-6), a pro-inflammatory cytokine associated with cutaneous inflammation. In an approach to identify the down-stream signaling mechanism by which 12-HHT down-regulates UVB-induced IL-6 synthesis in keratinocytes, we observed that 12-HHT inhibits the UVB-stimulated activation of p38 mitogen-activated protein kinase (MAPK) and nuclear factor kappa B (NF-kappaB). In addition, we found that 12-HHT markedly up-regulates MAPK phosphatase-1 (MKP-1), a critical negative regulator of p38 MAPK. When MKP-1 was suppressed by siRNA knock-down, the 12-HHT-mediated inhibitory effects on the UVB-stimulated activation of p38 MAPK and NF-kappaB, as well as the production of IL-6, were attenuated in HaCaT cells. Taken together, our results suggest that 12-HHT exerts anti-inflammatory effect via up-regulation of MKP-1, which negatively regulates p38 MAPK and NF-kappaB, thus attenuating IL-6 production in UVB-irradiated HaCaT cells. Considering the critical role of IL-6 in cutaneous inflammation, our findings provide the basis for the application of 12-HHT as a potential anti-inflammatory therapeutic agent in UV-induced skin diseases.
Anti-Inflammatory Agents, Non-Steroidal/pharmacology ; Cell Line ; Dual Specificity Phosphatase 1/biosynthesis/genetics ; Enzyme Activation ; Fatty Acids, Unsaturated/*pharmacology ; Humans ; Interleukin-6/*biosynthesis ; Keratinocytes/*metabolism/radiation effects ; NF-kappa B/metabolism ; RNA Interference ; RNA, Small Interfering ; Receptors, Leukotriene B4/genetics ; Signal Transduction/drug effects ; Skin Diseases/drug therapy ; *Ultraviolet Rays ; Up-Regulation ; p38 Mitogen-Activated Protein Kinases/metabolism