Investigação do papel das plaquetas na resposta imune alérgica pulmonar e sistêmica em modelo murino

Abstract

Allergic asthma is a chronic inflammatory disease of the airways, characterized by a Th2-skewed immune response, eosinophilia, and elevated IgE production. Recent evidence indicates that, beyond their classical role in hemostasis, platelets also participate in inflammatory and immunological processes by interacting with leukocytes and modulating the adaptive immune response. However, their role in allergic asthma remains incompletely understood. This study aimed to investigate the contribution of platelets to the development of allergic processes in secondary lymphoid organs and pulmonary allergic inflammation using a murine experimental model. Female Balb/c mice were sensitized and challenged with ovalbumin and treated with anti-CD41 to induce platelet depletion. During pulmonary allergic responses, increased levels of IL-5, CCL11, and PF4 were observed, along with both local and systemic eosinophilia. Under these conditions, enhanced formation of platelet–leukocyte aggregates was detected, particularly with eosinophils, alveolar macrophages, and B lymphocytes. Partial platelet depletion by anti-CD41 treatment led to reduced plasma PF4, decreased eosinophilic infiltration, and lower formation of platelet–leukocyte aggregates in the lungs. Consistently, a reduction in Th2 lymphocytes was also observed in mediastinal lymph nodes. The treatment further induced changes in IgG1⁺ and IgE⁺ B cell subpopulations in peripheral lymphoid organs, depending on the protocol phase. Nevertheless, serum levels of antibodies produced by these B cell subsets were not altered; instead, their functional quality was impaired, as evidenced by reduced avidity and diminished formation of secondary lymphoid follicles in the spleen. Altogether, these findings demonstrate that platelets actively contribute to pulmonary allergy by modulating distinct aspects of the immune response, with variable impact depending on the phase of inflammation.