Title: The Role of Platelets in Allergic Inflammation and Asthma
Abstract: Platelets are a kind of blood cells derived from bone marrow megakaryocytes and play essential roles in thrombosis, hemostasis, and tissue repair. Platelets have been found to be crucially involved in various immune responses and actively involved in the pathogenesis of allergic diseases such as allergic asthma. Patients with allergic asthma have lower platelet counts and increased levels of markers of platelet activation after allergen exposure. Platelets have been found extravascularly in the airways, and platelet products have been measured in bronchoalveolar lavage (BAL) fluid of asthmatic patients. Platelets are also crucially involved in the development of allergic diseases, including the development of allergic asthma via the regulation of allergic inflammation, especially type 2 inflammation mediated by active platelet-derived IL-33 protein activation. Both platelets and IL-33 are activated by tissue damage and involved in biological defense mechanisms and initiation of tissue repair. Therefore, platelets may be involved in the development of steroid-refractory asthma, including irreversible airway remodeling phenotypes.