RESUMO
The ability of the immune system to discriminate self from non-self is essential for eradicating microbial pathogens but is also responsible for allograft rejection. Whether it is possible to selectively suppress alloresponses while maintaining anti-pathogen immunity remains unknown. We found that mice deficient in coronin 1, a regulator of naive T cell homeostasis, fully retained allografts while maintaining T cell-specific responses against microbial pathogens. Mechanistically, coronin 1-deficiency increased cyclic adenosine monophosphate (cAMP) concentrations to suppress allo-specific T cell responses. Costimulation induced on microbe-infected antigen presenting cells was able to overcome cAMP-mediated immunosuppression to maintain anti-pathogen immunity. In vivo pharmacological modulation of this pathway or a prior transfer of coronin 1-deficient T cells actively suppressed allograft rejection. These results define a coronin 1-dependent regulatory axis in T cells important for allograft rejection and suggest that modulation of this pathway may be a promising approach to achieve long-term acceptance of mismatched allografts.
Assuntos
Rejeição de Enxerto/imunologia , Transplante de Coração , Infecções/imunologia , Proteínas dos Microfilamentos/metabolismo , Transplante de Pele , Linfócitos T/imunologia , Aloenxertos/imunologia , Animais , Antígenos de Bactérias/imunologia , Antígenos de Fungos/imunologia , Antígenos Virais/imunologia , Células Cultivadas , AMP Cíclico/imunologia , Sobrevivência de Enxerto , Homeostase/genética , Humanos , Imunidade , Terapia de Imunossupressão , Camundongos , Camundongos Endogâmicos BALB C , Camundongos Endogâmicos C57BL , Camundongos Knockout , Transdução de Sinais , Tolerância ao TransplanteRESUMO
Following thymic maturation, T cells egress as recent thymic emigrants to peripheral lymphoid organs where they undergo an additional maturation step to mature naive T cells that circulate through secondary lymphoid organs ready to be activated upon pathogenic challenges. Thymic maturation and peripheral T cell survival depend on several signaling cascades, but whether a dedicated mechanism exists that exclusively regulates homeostasis of mature naive T cells without affecting thymocytes and/or recent thymic emigrants remains unknown. In this article, we provide evidence for a specific and exclusive role of the WD repeat containing protein coronin 1 in the maintenance of naive T cells in peripheral lymphoid organs. We show that coronin 1 is dispensable for thymocyte survival and development, egress from the thymus, and survival of recent thymic emigrants. Importantly, coronin 1-deficient mice possessed comparable levels of peripheral T cells within the first 2 wk after birth but failed to populate the peripheral T cell compartment at later stages. Furthermore, dendritic cell- and IL-2/7-dependent T cell survival was found to be independent of coronin 1. Together, these results suggest the existence of a hitherto unrecognized coronin 1-dependent decision switch early during life that is responsible for peripheral naive T cell survival and homeostasis.