Kanaoka Y.,Jeff and Penny Vinik Center for Allergic Disease Research |
Kanaoka Y.,Harvard University |
Boyce J.A.,Jeff and Penny Vinik Center for Allergic Disease Research |
Boyce J.A.,Harvard University
Allergy, Asthma and Immunology Research | Year: 2014
Cysteinyl leukotrienes (cys-LTs) are potent mediators of inflammation derived from arachidonic acid through the 5-lipoxygenase/leukotriene C4 synthase pathway. The derivation of their chemical structures and identification of their pharmacologic properties predated the cloning of their classical receptors and the development of drugs that modify their synthesis and actions. Recent studies have revealed unanticipated insights into the regulation of cys-LT synthesis, the function of the cys-LTs in innate and adaptive immunity and human disease, and the identification of a new receptor for the cys-LTs. This review highlights these studies and summarizes their potential pathobiologic and therapeutic implications. © Copyright The Korean Academy of Asthma, Allergy and Clinical Immunology.
Liu T.,Harvard University |
Liu T.,Brigham and Women's Hospital |
Garofalo D.,Brigham and Women's Hospital |
Feng C.,Brigham and Women's Hospital |
And 9 more authors.
Journal of Immunology | Year: 2015
Cysteinyl leukotrienes (cysLTs) are bronchoconstricting lipid mediators that amplify eosinophilic airway inflammation by incompletely understood mechanisms. We recently found that LTC4, the parent cysLT, potently activates platelets in vitro and induces airway eosinophilia in allergen-sensitized and -challenged mice by a platelet- and type 2 cysLT receptor-dependent pathway. We now demonstrate that this pathway requires production of thromboxane A2 and signaling through both hematopoietic and lung tissue-associated T prostanoid (TP) receptors. Intranasal administration of LTC4 to OVA-sensitized C57BL/6 mice markedly increased the numbers of eosinophils in the bronchoalveolar lavage fluid, while simultaneously decreasing the percentages of eosinophils in the blood by a TP receptor-dependent mechanism. LTC4 upregulated the expressions of ICAM-1 and VCAM-1 in an aspirin-sensitive and TP receptor-dependent manner. Both hematopoietic and nonhematopoietic TP receptors were essential for LTC4 to induce eosinophil recruitment. Thus, the autocrine and paracrine functions of thromboxane A2 act downstream of LTC4/type 2 cysLT receptor signaling on platelets to markedly amplify eosinophil recruitment through pulmonary vascular adhesion pathways. The findings suggest applications for TP receptor antagonists in cases of asthma with high levels of cysLT production. Copyright © 2015 by The American Association of Immunologists, Inc.
Laidlaw T.M.,Harvard University |
Laidlaw T.M.,Brigham and Women's Hospital |
Laidlaw T.M.,Jeff and Penny Vinik Center for Allergic Disease Research |
Kidder M.S.,Brigham and Women's Hospital |
And 16 more authors.
Blood | Year: 2012
Cysteinyl leukotriene (cysLT) overproduction is a hallmark of aspirin-exacerbated respiratory disease (AERD), but its mechanism is poorly understood. Because adherent platelets can convert the leukocyte-derived precursor leukotriene (LT)A 4 to LTC 4, the parent cysLT, through the terminal enzyme LTC 4 synthase, we investigated the contribution of platelet-dependent transcellular cysLT production in AERD. Nasal polyps from subjects with AERD contained many extravascular platelets that colocalized with leukocytes, and the percentages of circulating neutrophils, eosinophils, and monocytes with adherent platelets were markedly higher in the blood of subjects with AERD than in aspirintolerant controls. Platelet-adherent subsets of leukocytes had higher expression of several adhesion markers than did platelet nonadherent subsets. Adherent platelets contributed more than half of the total LTC 4 synthase activity of peripheral blood granulocytes, and they accounted for the higher level of LTC 4 generation by activated granulocytes from subjects with AERD compared with aspirin-tolerant controls. Urinary LTE 4 levels, a measure of systemic cysLT production, correlated strongly with percentages of circulating platelet-adherent granulocytes. Because platelet adherence to leukocytes allows for both firm adhesion to endothelial cells and augmented transcellular conversion of leukotrienes, a disturbance in plateletleukocyte interactions may be partly responsible for the respiratory tissue inflammation and the overproduction of cysLTs that characterize AERD. © 2012 by The American Society of Hematology.
PubMed | Jeff and Penny Vinik Center for Allergic Disease Research
Type: Journal Article | Journal: Journal of immunology (Baltimore, Md. : 1950) | Year: 2013
Leukotriene C4 (LTC4) and its extracellular metabolites, LTD4 and LTE4, mediate airway inflammation. They signal through three specific receptors (type 1 cys-LT receptor [CysLT1R], CysLT2R, and GPR99) with overlapping ligand preferences. In this article, we demonstrate that LTC4, but not LTD4 or LTE4, activates mouse platelets exclusively through CysLT2R. Platelets expressed CysLT1R and CysLT2R proteins. LTC4 induced surface expression of CD62P by wild-type mouse platelets in platelet-rich plasma (PRP) and caused their secretion of thromboxane A2 and CXCL4. LTC4 was fully active on PRP from mice lacking either CysLT1R or GPR99, but completely inactive on PRP from CysLT2R-null (Cysltr2(-/-)) mice. LTC4/CysLT2R signaling required an autocrine ADP-mediated response through P2Y12 receptors. LTC4 potentiated airway inflammation in a platelet- and CysLT2R-dependent manner. Thus, CysLT2R on platelets recognizes LTC4 with unexpected selectivity. Nascent LTC4 may activate platelets at a synapse with granulocytes before it is converted to LTD4, promoting mediator generation and the formation of leukocyte-platelet complexes that facilitate inflammation.