Monday, January 22, 2018

Type 2 Cysteinyl Leukotriene Receptors Drive IL-33-Dependent Type 2 Immunopathology and Aspirin Sensitivity [ALLERGY AND OTHER HYPERSENSITIVITIES]

Cysteinyl leukotrienes (cysLTs) facilitate mucosal type 2 immunopathology by incompletely understood mechanisms. Aspirin-exacerbated respiratory disease, a severe asthma subtype, is characterized by exaggerated eosinophilic respiratory inflammation and reactions to aspirin, each involving the marked overproduction of cysLTs. Here we demonstrate that the type 2 cysLT receptor (CysLT2R), which is not targeted by available drugs, is required in two different models to amplify eosinophilic airway inflammation via induced expression of IL-33 by lung epithelial cells. Endogenously generated cysLTs induced eosinophilia and expanded group 2 innate lymphoid cells (ILC2s) in aspirin-exacerbated respiratory disease–like Ptges–/– mice. These responses were mitigated by deletions of either Cysltr2 or leukotriene C4 synthase (Ltc4s). Administrations of either LTC4 (the parent cysLT) or the selective CysLT2R agonist N-methyl LTC4 to allergen sensitized wild-type mice markedly boosted ILC2 expansion and IL-5/IL-13 generation in a CysLT2R-dependent manner. Expansion of ILC2s and IL-5/IL-13 generation reflected CysLT2R-dependent production of IL-33 by alveolar type 2 cells, which engaged in a bilateral feed-forward loop with ILC2s. Deletion of Cysltr1 blunted LTC4-induced ILC2 expansion and eosinophilia but did not alter IL-33 induction. Pharmacological blockade of CysLT2R prior to inhalation challenge of Ptges–/– mice with aspirin blocked IL-33–dependent mast cell activation, mediator release, and changes in lung function. Thus, CysLT2R signaling, IL-33–dependent ILC2 expansion, and IL-33–driven mast cell activation are necessary for induction of type 2 immunopathology and aspirin sensitivity. CysLT2R-targeted drugs may interrupt these processes.



from The Journal of Immunology current issue http://ift.tt/2n4D9ES

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