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Rationale: Daily high-dose aspirin therapy benefits many patients with aspirin-exacerbated respiratory disease but provides no benefit for aspirin-tolerant patients with asthma. Type 2 inflammation characterizes aspirin-exacerbated respiratory disease. Objectives: To determine whether high-dose aspirin therapy changes biomarkers of type 2 inflammation in aspirin-exacerbated respiratory disease. Methods: Forty-two subjects with aspirin-exacerbated respiratory disease underwent an aspirin desensitization and were placed on high-dose aspirin (1,300 mg daily). Fifteen aspirin-tolerant subjects with asthma were also placed on high-dose aspirin. Biologic specimens and clinical parameters were collected at baseline and after 8 weeks on aspirin. Urinary eicosanoids, plasma tryptase and cytokine levels, platelet-leukocyte aggregates, and granulocyte transcripts were assessed. Measurements and Main Results: Eight weeks of high-dose aspirin decreased nasal symptoms and urinary prostaglandin E metabolite ( P  < 0.05) and increased urinary leukotriene E 4 ( P  < 0.01) levels in subjects with aspirin-exacerbated respiratory disease, but not in those with aspirin-tolerant asthma. Urinary prostaglandin D 2 and thromboxane metabolites decreased in both groups. Only in subjects with aspirin-exacerbated respiratory disease, exhaled nitric oxide ( P  < 0.05), plasma tryptase ( P  < 0.01), and blood eosinophil ( P  < 0.01) and basophil ( P  < 0.01) counts increased and plasma tryptase correlated with eosinophil counts (Pearson r  = 0.514; P  < 0.01) on aspirin. After correction for eosinophil counts, aspirin-induced changes in blood granulocyte transcripts did not differ between groups. Aspirin had no effect on platelet-leukocyte aggregates, platelet activation markers, or plasma cytokines in either group. Conclusions: High-dose aspirin therapy for 8 weeks paradoxically increases markers of type 2 inflammation in subjects with aspirin-exacerbated respiratory disease, despite reducing nasal symptoms. This effect of aspirin is unique to aspirin-exacerbated respiratory disease and not observed in subjects with aspirin-tolerant asthma.

Objectives/hypothesis: Clinically, inflammatory polyps are found in the middle turbinate (MT) in patients with chronic rhinosinusitis (CRS) but not in the inferior turbinate (IT). The purpose of this study was to investigate differences in protein expression between IT and MT tissue in patients with CRS., Study Design: Prospective cohort., Methods: Pathologic specimens obtained from patients with CRS undergoing functional endoscopic sinus surgery with IT reduction were evaluated by immunohistochemical analysis of inflammatory markers cysteinyl leukotriene 1 receptor (CysLT1R), toll-like receptor 2 (TLR2), and vascular cell adhesion molecule 1 (VCAM1). Protein expression was quantified with nuance multispectral analysis and results compared between MT and IT tissue., Results: The total expression of VCAM1 and CysLT1R was decreased in the IT compared to the MT. There was no difference in total TLR2 expression between the IT and MT. When comparing patients with eosinophilic CRS to noneosinophilic CRS (neCRS), there was decreased expression of VCAM1 in the IT of patients with neCRS. When comparing patients with nasal polyposis to those without polyps, there was decreased expression of VCAM1 in the IT of patients without polyps., Conclusions: There is a difference in protein receptor expression of VCAM1 and CysLT1R in MT compared to IT tissue. Although the leukotrienes are a well-known target for treatment of chronic sinusitis, this is the first study demonstrating an upregulation of VCAM1 expression in the MT and could be a potential future target for the treatment of CRS., Level of Evidence: NA Laryngoscope, 126:E179-E183, 2016., (© 2015 The American Laryngological, Rhinological and Otological Society, Inc.)

Objective: To 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., Methods: Sixty 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., Results: The 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)., Conclusions: CysLTR-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.

Objective: This study analyzed the ability of montelukast, a cysteinyl-leukotrienes receptor antagonist and anti-inflammatory agent, to produce a consistent tocolytic effect alone or in combination with nifedipine, a calcium (Ca(2+)) channel blocker currently used in clinical practice., Study Design: Uterine biopsies were obtained from consenting women undergoing elective cesarean sections at term (n=20). Myometrial microsomal fractions were analyzed by immunoblotting to quantify relative cysteinyl leukotrienes receptor 1 (CysLTR1) levels. Isometric tension measurements were performed in vitro on human myometrial strips (n=120) in isolated organ baths in order to establish concentration-response curves to montelukast and to quantify changes in Ca(2+) sensitivity on β-escin permeabilized tissues., Results: Immunodetection analysis revealed the presence of CysLTR1 receptor in uterine tissues, fetal membranes and placenta. A significant increase in area under the curve (AUC) was quantified following the addition of leukotriene D4 (LTD4) (0.01-0.3 μM), an end-product of the lipoxygenase pathway. Conversely, addition of montelukast produced a significant tocolytic effect by decreasing the frequency and AUC (IC₅₀=1 μM). Moreover, addition of montelukast also resulted in a reduced Ca(2+) sensitivity as compared to control tissues (EC₅₀ values of 654 and 403 nM; p=0.02 at pCa 6), while an additive effect was observed in combination with 0.1 nM nifedipine (p=0.004)., Conclusion: This original study demonstrates the potency of montelukast as a tocolytic agent in an in vitro human uterine model. Montelukast, in combination with nifedipine, could represent a therapeutic approach to reduce inflammation associated with prematurity while facilitating the inhibition of preterm labor., (Copyright © 2014 Elsevier Ireland Ltd. All rights reserved.)

The objective of this study was to analyze the expression of cysteinyl leukotriene 1 (CysLT1) receptor and glucocorticoid receptors (GRs) in nasal polyps, and to evaluate the relationship between the expression of CysLT1 receptors and that of GRs. Nasal polyps were taken from 32 patients of chronic rhinosinusitis with nasal polyposis. Samples of middle turbinate from seven healthy subjects were used as controls. Specimens were immunohistochemically stained for CysLT1 receptor, GR-α and GR-β receptor, and were quantified in the unit area of the tissues. Numbers of CysLT1 receptor-positive cells were much increased in nasal polyps than in middle turbinate (281 ± 67 vs. 157 ± 85 cells/mm(2), P = .01). There was no significant difference in the numbers of GR-α positive cells between nasal polyps and normal turbinate mucosa. GR-β positive cells were increased in nasal polyps as compared to normal turbinate mucosa (36 ± 8 vs. 19 ± 7 cells/mm(2), P = .03). A significant relationship was found between the expression of CysLT1 receptor and GR-β in nasal polyps (R = .525, P = .04), whereas there was no significant relationship between the expression of CysLT1 receptor and GR-α in nasal polyps. Our study shows that CysLT1 receptor expression predominates on GR-β over-expressed polyps. This may suggest the additional effect of CysLT1 receptor antagonist for the treatment of nasal polyposis resistant to steroid alone.

Objectives: Cysteinyl leukotrienes have been implicated in the pathogenesis of adenotonsillar hypertrophy in children with obstructive sleep apnea (OSA). This study aimed to quantify the expression of cysteinyl leukotriene receptors (CysLT(1), CysLT(2)) by tonsillar lymphocyte subpopulations from children with OSA and to make comparisons to lymphocyte subpopulations from control subjects with recurrent tonsillitis (RT)., Methods: Tonsillar tissue from children with OSA or RT was studied for CysLT(1) and CysLT(2) expression by RT-PCR, flow cytometry (FC), and immunofluorescence., Results: Ten children with OSA and 10 control subjects were recruited. In OSA participants, CysLT(1)+ fraction of small-size CD19+ B-lymphocytes was similar to the CysLT(1)+ CD3+ T-lymphocytes fraction (FC: 36.5 [16.5-55.4] vs. 14 [2.8-22.1]) (p>0.05) and higher than the CysLT(1)+ moderate/large-size CD19+ B-lymphocytes fraction (6.6 [1.5-14.4]) (p<0.01). Similar trends were recognized for CysLT(2). CysLT(1) and CysLT(2) immunoreactivity was detected by immunofluorescence in the tonsillar mantle zones (small B-lymphocytes) and the extrafollicular areas (T-lymphocytes). Compared to subjects with RT, children with OSA had significantly higher expression of CysLT(1) in small-size CD19+ B-lymphocytes (FC) and in CD3+ T-lymphocytes (RT-PCR and FC) (p<0.05)., Conclusions: Increased expression of leukotriene receptors by immunologically active tonsillar areas in children with OSA is a potential therapeutic target for pediatric sleep apnea., (Copyright © 2012 Elsevier B.V. All rights reserved.)

Snoring is the most characteristic symptom of obstructive sleep-disordered breathing (SDB) and recurrent wheezing is the most common clinical manifestation of asthma. The purpose of the present review is to outline the impact of SDB and recurrent wheezing/asthma on sleep quality and to summarize the epidemiologic and pathophysiologic evidence supporting an association between the two disorders. Enlarged tonsils and adenoid or obesity predispose to obstructive sleep apneas and hypopneas which are accompanied by arousals, restless sleep, and frequently daytime sleepiness, inattention, hyperactivity, and academic difficulties. Subjects with history of wheezing are also at risk for sleep disturbance and daytime cognitive dysfunction. Asthmatic children have more frequent snoring, apneas, and hypopneas during sleep than non-asthmatic subjects and tonsillar hypertrophy mediates at least in part this epidemiologic association. In addition, preliminary evidence indicates that treatment of sleep apnea with adenotonsillectomy results in improved control of coexisting asthma. Elevated concentrations of leukotrienes and oxidative stress markers have been detected in the exhaled breath condensate of children with asthma and probably contribute to bronchoconstriction. Moreover, sleep apneic children have increased expression of leukotrienes and leukotriene receptors in adenotonsillar tissue. Viral respiratory infections may induce inflammation and oxidative stress in the asthmatic airway enhancing not only bronchospasm, but also biosynthesis of leukotrienes within pharyngeal lymphoid tissues, which promote adenotonsillar enlargement and sleep apnea. In conclusion, taking under consideration the epidemiologic association between obstructive SDB and asthma, when one of the two disorders is diagnosed, the possibility of the other disease being present should be entertained. Pediatr. Pulmonol. 2011; 46:1047-1054. © 2011 Wiley Periodicals, Inc., (Copyright © 2011 Wiley Periodicals, Inc.)

Leukotriene B(4) (LTB(4)), a potent chemotactic and immune-modulating mediator, signals via two receptors, BLT(1) and BLT(2). Recently, we reported that BLT(1) is the predominating BLT expressed on human umbilical vein endothelial cells (HUVEC), and that BLT(1) mediated functions are enhanced by LTB(4) and lipopolysaccharide (LPS), but not by TNFα. Here, we demonstrate that BLT(1) is found on the outer cell membrane of HUVECs but also in intracellular granules, co-localized with monocyte chemotactic protein-1 and P-selectin, but not with interleukin-8 and von Willebrand factor. Upon stimulation with LTB(4) or LPS, more BLT(1) protein is found, now evenly distributed over the cytoplasm and in the cell nucleus, but less on the cell surface. An MAP kinase inhibitor prevented this enhancement and translocation, suggesting this signaling pathway to be crucial. Thus, BLT(1), a G-protein-coupled 7-transmembrane receptor, is located in various subcellular compartments in endothelial cells, which may have implications for cellular LT dependent responses and target accessibility for BLT(1) antagonists., (Copyright © 2010 Elsevier Inc. All rights reserved.)

The mechanism underlying airway hyperresponsiveness (AHR), a characteristic feature of asthma, remains obscure. We attempted to elucidate the mechanism responsible for the different degrees of AHR in two mouse strains, BALB/c and C57BL/6, following exposure to an anaphylactic trigger. When ovalbumin (OVA)-sensitized mice were challenged daily with OVA for up to three consecutive days, the BALB/c mice showed a higher degree of airway responsiveness to methacholine than did C57BL/6. Following the OVA challenge, eosinophils and macrophages in bronchoalveolar lavage fluid (BALF) from BALB/c increased significantly in number compared to those from C57BL/6. BALB/c mice also exhibited a higher serum IgE level than that of C57BL/6 after OVA challenge. The enhanced AHR and eosinophilic infiltration in BALF were significantly reduced by pretreatment with a selective cysteinyl-leukotriene type 1 receptor (cysLT(1)R) antagonist, montelukast. In the in vitro study, cysLT production was significantly lower in the dissected lung tissue from BALB/c than in tissue from C57BL/6 when both groups were stimulated with saline. The lungs from BALB/c generated significantly larger amounts of cysLTs on incubation with OVA rather than with saline, while the lungs from C57BL/6 did not show any significant increase in cysLTs with antigen stimulation. Significant upregulation of cysLT(1)R and cysLT(2)R mRNA expression was induced by OVA challenge in the lungs of BALB/c, but not in those of C57BL/6. It is suggested that, after an anaphylactic reaction, the degree of AHR is dependent on the genetic background and that cysLTs play an important role in the mechanism involved.

Background: Montelukast (MNT), a cysteinyl-leukotriene receptor (Cys-LTR) antagonist, has anti-inflammatory activity in the treatment of allergic diseases. If this effect is due only to blocking leukotrienes or also owing to inhibiting proliferation and survival of inflammatory cells, is actually unknown., Objective: Testing the hypothesis that MNT could influence T lymphocyte functional behaviour in vitro., Methods: Normal T lymphocytes were analysed for surface expression of Cys-LTR(1) and Cys-LTR(2) by means of monoclonal antibodies (mAbs), in the resting state and after activation with T helper type 2 cytokine or T cell receptor (TcR) stimulation. Proliferative activity, as well as IL-4 andIFN-gamma production, were simultaneously determined in samples exposed to molar concentrations of MNT from 10(-8) to 10(-5). Programmed cell death in cultured samples was evaluated by means of propidium iodide and fluorescein isothiocyanate-conjugated anti-Annexin V mAb staining. The complementary DNA microarray technique was adopted to identify gene products involved in apoptosis induction., Results: Resting T cells expressed low levels of Cys-LTR. Upon anti-CD3 mAb activation, a progressive increase in Cys-LTR(1) and -LTR(2) expression was observed. Exposure to MNT reduced proliferative response to TcR engagement, increased IFN-gamma production and led to apoptosis at minimal concentrations of 10(-6) M. A progressive loss in BAD and B cell lymphoma/leukaemia-2 activities, and an increase in the expression of CD27, TRAF3, TRAIL, p53 and Fas genes were also observed., Conclusions: Biological effects of MNT delineate a complex picture of gene activation and repression, probably induced by Cys-LTR blockade. The induction of apoptosis in allergen-specific T cell population, as a final result, appears fundamental in the treatment of asthma.

The cysteinyl leukotrienes (cys-LTs) are a family of potent bioactive lipids that act through two structurally divergent G protein-coupled receptors, termed the CysLT(1) and CysLT(2) receptors. The cloning and characterization of these two receptors has not only reconciled findings of previous pharmacologic profiling studies of contractile tissues, but also has uncovered their expression on a wide array of circulating and tissue-dwelling leukocytes. With the development of receptor-selective reagents, as well as mice lacking critical biosynthetic enzymes, transporter proteins, and the CysLT(1) receptor, diverse functions of cys-LTs and their receptors in immune and inflammatory responses have been identified. We review cys-LT biosynthesis; the molecular biology and distribution of the CysLT(1) and CysLT(2) receptors; the functions of cys-LTs and their receptors in the recruitment and activation of effector leukocytes and induction of adaptive immunity; and the development of fibrosis and airway remodeling in animal models of lung injury and allergic inflammation.

Background: The cysteinyl leukotrienes (CysLT) are lipid mediators that have been implicated in the pathogenesis of allergic diseases. Pharmacological studies using CysLTs indicate that two classes of receptors, named CysLT1 and CysLT2 receptor, exist. The former is sensitive to the CysLT1 antagonist currently used to treat asthma and allergic rhinitis. Recently, the cDNA for human CysLT1 and CysLT2 receptor have been cloned, making it now possible to study the gene expression of CysLTs receptors., Objective: We have used reverse transcription and polymerase chain reaction (RT-PCR) to study the gene expression of CysLT1 and CysLT2 receptor and in situ hybridization to determine the distribution of CysLT1 receptor mRNA in human nasal mucosa. In addition, the distribution of the CysLT1 receptor protein was studied by immunohistochemistry., Methods: Human turbinates were obtained after turbinectomy from six patients with nasal obstruction refractory to medical therapy. Total RNA was isolated from human nasal mucosa and both CysLT1 and CysLT2 receptor mRNA was detected in these tissues by using RT-PCR. For in situ hybridization study of human nasal mucosa, we used biotin-labelled oligonucleotides probes encoding human CysLT1 receptor cDNA. To identify the cells expressing the CysLT1 receptor protein, double immunostaining was performed by using anti-CysLT1 receptor antibody and monoclonal antileucocyte antibodies., Results: RT-PCR analysis of total nasal RNA demonstrated the expression of both CysLT1 receptor and CysLT2 receptor mRNA. In situ hybridization indicated high levels of CysLT1 receptor hybridization in blood vessels and the interstitial cells, but a sparse signal in airway epithelium and submucosal glands. The immunohistochemical studies revealed that anti-CysLT1 receptor antibody labelled eosinophils, mast cells, macrophages, neutrophils and vascular endothelial cells in the nasal mucosa., Conclusion: The results may have an important clinical implication and also promote further investigation of the regulation of CysLT1 receptor in health and disease.

Objective: This article presents information on the origin of leukotrienes (LTs) and the development of antileukotriene (anti-LT) agents. After reading this article, readers should have an understanding of the chemical mediators involved in the pathogenesis of asthma, the structural features of LTs, and the role of anti-LTs in the management of asthma symptoms., Data Sources: Studies considered relevant and appropriately controlled were used. Only literature in the English language was reviewed., Study Selection: Material was taken from academic/scholarly journals and abstracts., Results: One of the important chemical mediators implicated in the pathogenesis of asthma is the slow-reacting substance of anaphylaxis, which was subsequently found to comprise LTs C4, D4, and E4. 5-lipoxygenase products from arachidonic acid metabolism, LTs are released from the lung tissue of asthmatic patients and purified human lung mast cells by antigens. The LTs directly induce contraction of bronchial smooth muscle. The use of anti-LT agents, particularly the receptor antagonists zafirlukast and montelukast and the biosynthesis inhibitor zileuton, reverses the bronchoconstrictive effects of LTs and significantly improve asthma symptoms., Conclusions: Extensive in vitro and in vivo evidence supports the role of LTs in the pathogenesis of asthma. Their discovery has had a significant impact on treatment strategies, including the use of anti-LT agents, for the management of asthma.

The cysteinyl leukotrienes (CysLTs) are important mediators of human asthma. Pharmacologic and clinical studies show that the CysLTs exert most of their bronchoconstrictive and proinflammatory effects through activation of a putative, 7-transmembrane domain, G-protein-coupled receptor, the CysLT1 receptor. The initial molecular characterization of the CysLT1 receptor showed by in situ hybridization, the presence of CysLT1 receptor messenger RNA (mRNA) in human lung smooth-muscle cells and lung macrophages. We confirmed the results of these in situ hybridization analyses for the CysLT1 receptor, and produced the first immunohistochemical characterization of the CysLT1 receptor protein in human lung. The identification of the CysLT1 receptor in the lung is consistent with the antibronchoconstrictive and antiinflammatory actions of CysLT1 receptor antagonists. We also report the expression of CysLT1 receptor mRNA and protein in most peripheral blood eosinophils and pregranulocytic CD34+ cells, and in subsets of monocytes and B lymphocytes.

Background: Leukotrienes are a class of biologically active lipids that have potent effects on the heart. To assess their role in coronary artery disease, we compared the contractile responses of leukotriene C4 (LTC4) and leukotriene D4 (LTD4) and their binding activity in both atherosclerotic and nonatherosclerotic human coronary arteries. We also studied expression of the enzymes that control their formation to understand how the 5-lipoxygenase (5-LO) pathway is activated in the coronary arteries., Methods and Results: The capacity of leukotrienes to affect coronary vessel tone and the influence of atherosclerosis was tested in organ baths. Leukotriene receptors were examined by autoradiography, and antibody binding to the various enzymes responsible for their formation was assessed by use of immunocytochemistry. Nonatherosclerotic coronary artery ring segments were unresponsive to LTC4 and LTD4. In contrast, LTC4 and LTD4 induced concentration-dependent contractions in atherosclerotic coronary arteries. Specific [3H]-LTC4 but not LTD4 binding to atherosclerotic coronary artery was evident, with no evidence of specific binding of [3H]-leukotrienes to nonatherosclerotic coronary artery. High-resolution autoradiography identified specific [3H]-LTC4 binding sites to smooth muscle cell and to regions of intimal proliferation and plaque. Cells showing positive antibody binding to 5-LO, FLAP (5-lipoxygenase activating protein), and leukotriene A4 hydrolase were also present in the coronary arteries and had a similar distribution to macrophages., Conclusions: Atherosclerosis is associated with a specific leukotriene receptor(s) capable of inducing hyperreactivity of human epicardial coronary arteries in response to LTC4 and LTD4.

1. Cysteinyl-leukotrienes cause contractions and/or relaxations of human isolated pulmonary vascular preparations. Although, the localization and nature of the receptors through which these effects are mediated have not been fully characterized, some effects are indirect and not mediated via the well-described LT1 receptor. 2. In human pulmonary veins (HPV) with an intact endothelium, leukotriene D4 (LTD4) induced contraction above basal tone. This response was observed at lower concentrations of LTD4 in the presence of nitric oxide synthase inhibitor N omega-nitro-L-arginine (L-NOARG). Contractions (in the absence and presence of L-NOARG) were partially blocked by the LT1 antagonists (MK 571 and ICI 198615). 3. LTD4 relaxed HPV previously contracted with noradrenaline. This relaxation was potentiated by LT1 antagonists, but was abolished by removal of the endothelium. LTD4 also relaxed human pulmonary arteries (HPA) precontracted with noradrenaline but this effect was not modified by LT1 antagonists. 4. The results suggest that contraction of endothelium-intact HPV by LTD4 is partially mediated via LT1 receptors. Further, in endothelium-intact HPV, this contraction was opposed by a relaxation induced by LTD4, dependent on the release of nitric oxide, which was mediated, at least in part, via a non-LT1 receptor. In addition, LTD4 relaxation on contracted HPA was not mediated by LT1 receptors. 5. The mechanical effects of LTD4 on human pulmonary vasculature are complex and involve both direct and indirect mechanisms mediated via at least two types of cysteinyl-leukotriene receptors.

This study focuses on possible functional defects of circulating mature neutrophils in chronic phase chronic myelogenous leukemia (CML) and their modulation by interferon-alpha (IFN-alpha). Polymorphonuclear cells (PMN) of seven untreated and nine IFN-alpha-treated patients were evaluated for the following parameters by the following methods: generation of oxygen species, by luminol-dependent chemiluminescence; leukotriene B4 (LTB4) generation, by high-performance liquid chromatography (HPLC); expression of LTB4 and formylmethionyl-leucyl phenylalanine (FMLP) receptor sites, by 3H-binding assay; and GTPase activity, by 32P-gamma-GTP. Compared to normal controls, reduced values were obtained in treated and untreated CML for most parameters studied. Therapy with IFN-alpha resulted in significantly diminished values for oxygen species (NaF stimulation) and LTB4 (FMLP stimulation) generation, as well as FMLP receptor expression as compared to untreated CML. We conclude that alterations at the level of oxygen species production, mediator generation, receptor expression, and transmembrane signaling are involved in functional defects of circulating mature neutrophils from CML patients. IFN-alpha seems to enhance some of these functional defects, but the clinical relevance of these findings has be elucidated.