The role of miRNA-155 in the immunopathogenesis of obliterative airway disease in mice induced by circulating exosomes from human lung transplant recipients with chronic lung allograft dysfunction

Human lung transplant recipients undergoing rejection induce circulatory exosomes with lung self-antigens (SAgs), K-alpha 1 Tubulin and Collagen V, and immunization of C57BL/6 mice with exosomes induced ob-literative airway disease (HEI-OAD). We analyzed whether exosomes with SAgs induced immunity in microRNA-155 knockout mice (miR-155KO), as microRNA-155 is an immune regulator. C57BL/6 and miR-155KO were immunized with exosomes from stable or chronic rejection (bronchiolitis obliterans syndrome (BOS) and on day 30, induction of exosomes, antibodies (Abs) to SAgs and cellular immunity were determined. C57BL/6 im-munized with exosomes from BOS developed OAD. These immunized animals also developed Abs to SAgs and increased frequency of SAg-specific IFN gamma and IL17-producing cells. In contrast, Abs to SAgs did not develop in miR-155KO and there was reduction in frequency of cells producing IL10. Upregulation of suppressor of cytokine signaling for lung inflammation was also noted resulting in abrogation of induction of exosomes with SAgs OAD.