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Biological effects of leukotriene E4 on eosinophils.

ABSTRACT: Studies demonstrate the existence of novel receptors for cysteinyl leukotrienes (CysLTs) that are responsive to leukotriene (LT) E4 and might be pathogenic in asthma. Given the eosinophilic infiltration in this disorder, we investigated eosinophil expression of P2Y12 and gpr99 and their capacity to respond to LTE4. Receptor transcript expression was investigated via quantitative PCR and surface protein expression via flow cytometry. We investigated LTE4 influences on eosinophils including Ca(+2) flux, cAMP induction, modulation of adhesion molecule expression, apoptosis and degranulation. Eosinophils displayed both transcript and surface protein expression of P2Y12 and gpr99. We could not find evidence of LTE4 activation of eosinophils, however, LTE4 induced cAMP expression, and preincubation of eosinophils with LTE4 inhibited degranulation. Even though eosinophils are an important source of CysLTs in AERD, eosinophils are not themselves the pro-inflammatory biological target and, in contrast, LTE4 via cAMP primarily elicits anti-inflammatory responses.

SUBMITTER: Steinke JW

PROVIDER: S-EPMC4127125 | biostudies-literature | 2014 Sep

REPOSITORIES: biostudies-literature

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Biological effects of leukotriene E4 on eosinophils.

Steinke John W JW Negri Julie J Payne Spencer C SC Borish Larry L

Prostaglandins, leukotrienes, and essential fatty acids 20140326 3

Studies demonstrate the existence of novel receptors for cysteinyl leukotrienes (CysLTs) that are responsive to leukotriene (LT) E4 and might be pathogenic in asthma. Given the eosinophilic infiltration in this disorder, we investigated eosinophil expression of P2Y12 and gpr99 and their capacity to respond to LTE4. Receptor transcript expression was investigated via quantitative PCR and surface protein expression via flow cytometry. We investigated LTE4 influences on eosinophils including Ca(+2) ...[more]

PMID: 24768603

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Project description:The movement of leukocytes into tissues is regulated by the local production of chemical mediators collectively referred to as chemoattractants. Although chemoattractants constitute a diverse array of molecules, including proteins, peptides, and lipids, they all appear to signal leukocytes through a related family of seven transmembrane-spanning G protein-coupled receptors. The eosinophil is a potent proinflammatory cell that is attracted into tissues during allergic inflammation, parasitic infection, and certain malignancies. Since the molecular mechanisms controlling eosinophil recruitment are incompletely understood, we performed a degenerate polymerase chain reaction on cDNA isolated from murine eosinophils to identify novel chemoattractant receptors. We report the isolation of a cDNA that encodes a 351-amino acid glycoprotein that is 78% identical to a human gene that has been reported to be a purinoceptor (P2Y7) and a leukotriene B4 (LTB4) receptor (BLTR). Chinese hamster ovary (CHO) cells transfected with this cDNA specifically bound [3H]LTB4 with a dissociation constant of 0.6 +/- 0.1 nM. Furthermore, LTB4 induced a dose-dependent intracellular calcium flux in transfected CHO cells. In contrast, [35S]dATP did not specifically bind to these transfectants. This mRNA was expressed at high levels in interleukin 5-exposed eosinophils, elicited peritoneal macrophages and neutrophils, and to a lesser extent interferon gamma stimulated macrophages. Low levels of expression were detected in the lung, lymph node, and spleen of unchallenged mice. Western blot analysis detected the mBLTR protein in murine eosinophils and alveolar macrophages as well as human eosinophils. In addition, elevated levels of mBLTR mRNA were found in the lungs of mice in a murine model of allergic pulmonary inflammation in a time course consistent with the influx of eosinophils. Our findings indicate that this murine receptor is an LTB4 receptor that is highly expressed on activated leukocytes, including eosinophils, and may play an important role in mediating eosinophil recruitment into inflammatory foci.

Project description:PurposeData on non-steroidal anti-inflammatory drug (NSAID) hypersensitivity in Southeast Asia are scarce. Increased urinary leukotriene E4 (uLTE4) levels have been suggested as a biomarker of NSAID-exacerbated respiratory disease (NERD). This study investigated clinical patterns of NSAID sensitivity in Thailand and the diagnostic roles of uLTE4 measurement in various phenotypes.MethodsThe clinical phenotypes in 92 Thai adults with cross-reactive NSAID hypersensitivity were characterized based on the clinical history and drug provocation. The uLTE4 levels were measured at baseline, after aspirin provocation and after desensitization.ResultsMore than half of the patients (56.5%) presented with cutaneous symptoms (NSAID-exacerbated cutaneous disease), while one-third (33.7%) developed symptoms in at least 2 systems (NSAID-induced blended reactions; NIBR). Fifty-two patients underwent drug provocation and 59.6% of them yielded positive results. After drug provocation, a significant number of patients with confirmed NSAID cross-reactivity experienced clinical symptoms in more than one organ system. The uLTE4 levels at baseline were comparable between the NSAID-tolerant and NSAID-sensitive groups, but were substantially increased after aspirin provocation predominantly in NERD (983.4 pg/mg creatinine) and NIBR (501.0 pg/mg creatinine) compared to NSAID-tolerant subjects (122.1 pg/mg creatinine, P < 0.01 and 0.05, respectively). The uLTE4 levels were elevated after aspirin desensitization, although nasal polyposis and asthma were under control in 3 NERD and 3 NIBR subjects.ConclusionsNIBR is not uncommon among NSAID-sensitive patients in Thailand. The diagnostic value of basal uLTE4 levels was limited, but increased uLTE4 levels upon aspirin provocation suggest NSAID cross-reactivity with respiratory components. This study indicates that aspirin desensitization, if necessary, might be effective in both NERD and NIBR.Trial registrationClinicalTrials.gov Identifier: NCT03849625.

Dataset Information

Biological effects of leukotriene E4 on eosinophils.

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Biological effects of leukotriene E4 on eosinophils.

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