Cysteinyl Leukotriene Receptor 2 Drives Lung Immunopathology Through a Platelet and High Mobility Box 1-Dependent Mechanism

Cysteinyl leukotrienes (cysLTs) facilitate eosinophilic mucosal type 2 immunopathology, especially in aspirin-exacerbated respiratory disease (AERD), by incompletely understood mechanisms. We now demonstrate that platelets, activated through the type 2 cysLT receptor (CysLT(2)R), cause IL-33-dependent immunopathology through a rapidly inducible mechanism requiring the actions of high mobility box 1 (HMGB1) and the receptor for advanced glycation end products (RAGE). Leukotriene C(4) (LTC(4)) induces surface HMGB1 expression by mouse platelets in a CysLT(2)R-dependent manner. Blockade of RAGE and neutralization of HMGB1 prevent LTC(4)-induced platelet activation. Challenges of AERD-like Ptges(−/−) mice with inhaled lysine aspirin (Lys-ASA) elicit LTC(4) synthesis and cause rapid intrapulmonary recruitment of platelets with adherent granulocytes, along with platelet- and CysLT(2)R-mediated increases in lung IL-33, IL-5, IL-13, and bronchoalveolar lavage fluid HMGB1. The intrapulmonary administration of exogenous LTC(4) mimics these effects. Platelet depletion, HMGB1 neutralization, and pharmacologic blockade of RAGE eliminate all manifestations of Lys-ASA challenges, including increase in IL-33, mast cell activation, and changes in airway resistance. Thus, CysLT(2)R signaling on platelets prominently utilizes RAGE/HMGB1 as a link to downstream type 2 respiratory immunopathology and IL-33-dependent mast cell activation typical of AERD. Antagonists of HMGB1 or RAGE may be useful to treat AERD and other disorders associated with type 2 immunopathology.