RESUMO
ABSTRACT Healthy aging is partly related to appropriate function of the immune system. As already reported, some changes in this system are observed, including reduced number and repertoire of T cells due to thymic involution, accumulation of memory T cells by chronic infections, homeostatic proliferation compensating for the number of naïve T cells, decreased proliferation of T cells against a stimulus, telomere shortening, replicative senescence of the T cells, and inflammaging, besides the accumulation of myeloid-derived suppressor cells. The purpose of this article is to clarify each of these changes, aiming to minimize limitations of immunosenescence. If such associations can be established, these cells may be used as early and less invasive markers of aging-related diseases, as well as to indicate interventions, evaluate the efficacy of interventions and be a tool to achieve longevity with quality of life.
RESUMO O envelhecimento saudável está relacionado, pelo menos em parte, com a função adequada do sistema imunológico. Isso porque já foi relatado que, com o envelhecimento, algumas mudanças desse sistema são observadas, como a diminuição da percentagem e do repertório de células T pela involução tímica, acúmulo de células T de memória por infecções crônicas, compensação do número de células T naïve por proliferação homeostática, diminuição da capacidade de proliferação das células T frente a um estímulo, encurtamento dos telômeros, senescência replicativa das células T, e inflammaging, além do acúmulo de células mieloides supressoras. Este artigo visa esclarecer cada uma das mudanças, mencionadas, com o intuito de buscar meios de minimizar as limitações da imunosenescência. Caso seja possível estabelecer tais relações, essas células podem ser utilizadas como marcadores precoces e pouco invasivos de doenças relacionadas ao envelhecimento, além da possibilidade de serem utilizadas para indicar intervenções, avaliar a eficácia das intervenções e como ferramenta para alcance da longevidade com qualidade de vida.
Assuntos
Humanos , Envelhecimento/imunologia , Linfócitos T/fisiologia , Imunossenescência/imunologia , Células Supressoras Mieloides/fisiologia , Adaptação Fisiológica/imunologia , Proliferação de Células/fisiologiaRESUMO
Immune thrombocytopenia (ITP) is a disease characterized by isolated thrombocytopenia. Abnormal effector T cell activation is an important mechanism in the pathogenesis of ITP. Regulatory T cells (Treg) have a strong immunosuppressive function for T cell activation and their importance in the pathophysiology and clinical treatment of ITP has been confirmed. Myeloid-derived suppressor cells (MDSCs) are other immunosuppressive cells, which can also suppress T cell activation by secreting arginase, iNOS and ROS, and are essential for Treg cells’ differentiation and maturation. Therefore, we speculate that MDSCs might also be involved in the immune-dysregulation mechanism of ITP. In this study, we tested MDSCs and Treg cells in peripheral blood samples of twenty-five ITP patients and ten healthy donors. We found that MDSCs and Treg cells decreased simultaneously in active ITP patients. Relapsed ITP patients showed lower MDSCs levels compared with new patients. All patients received immunosuppressive treatment including dexamethasone alone or in combination with intravenous immune globulin. We found that MDSCs’ level after treatment correlated with platelet recovery. Our study is the first that focused on MDSCs’ role in ITP. Based on our results, we concluded that circulating MDSCs could predict disease activity and treatment response in ITP patients. This preliminary conclusion indicates a substantial significance of MDSCs in the pathophysiology and clinical treatment of ITP, which deserves further investigation.
