Imunossenescência
Immunosenescence
Rosana C. Agondi; Luiz V. Rizzo; Jorge Kalil; Myrthes T. Barros
Resumo
Objetivo: Revisar as principais alterações do sistema imunológico que ocorrem com o envelhecimento.
Fontes dos dados: O método adotado foi a revisão narrativa da literatura. Foram analisados 33 artigos originais e de revisão indexados nos bancos de dados MEDLINE e LILACS de janeiro de 2000 a junho 2012.
Síntese dos dados: A imunossenescência é definida como um estado de função imunológica desregulada, nos idosos, que contribui para o aumento da suscetibilidade a infecções, câncer e autoimunidade, e redução da resposta vacinal. O processo de envelhecimento afeta ambos os ramos da imunidade, embora a imunidade inata pareça estar mais bem preservada. A capacidade de renovação das células do sistema imunológico, a partir das células-tronco hematopoéticas, diminui com a idade. As alterações nos precursores dos linfócitos B levam à diminuição do número de células maduras que deixam a medula óssea, enquanto a involução tímica leva a alterações substanciais no compartimento de células T. A imunossenescência caracteriza-se por um estado inflamatório crônico, denominado "inflamm-aging". Algumas associações entre infecção crônica virais e o envelhecimento são descritas, como por exemplo, a infecção crônica pelo CMV. A persistência viral no hospedeiro imunocompetente modula o sistema imunológico e dados científicos mostram que a infecção pelo CMV pode acelerar o envelhecimento do sistema imunológico e levar à inflamação crônica subclínica.
Conclusões: É importante considerar que todo indivíduo acima de 60 anos tem seu sistema imunológico sob suspeita e deve ser tratado de modo a minimizar as intervenções que possam comprometer ainda mais as funções efetoras/reguladoras da resposta imune.
Palavras-chave
Abstract
Objective: To review the main changes of the immune system that occur with aging.
Sources: The research method adopted was the narrative review of literature. A total of 33 original and review articles indexed in MEDLINE and LILACS from January 2000 to June 2012 were analysed.
Data summary: The immunosenescence is defined as a state of dysregulated immune function in elderly, which contributes to increased susceptibility to infections, cancer and autoimmunity, and poor vaccine response. The aging process affects both arms of the immune system, however, innate immunity appears to be better preserved. The renewal capacity of immune cells, from hematopoietic stem cells decreases with age. Changes in the precursors of B lymphocytes lead to a decrease in the number of mature B cells leaving the bone marrow while thymic involution related to aging leads to substantial changes in the T cell compartment. Immunosenescence is characterized by a chronic inflammatory state, known as “Inflamm-aging.” Some association between chronic infection with virus and aging are reported in the literature, for example, chronic infection with CMV. The viral persistence in immunocompetent host modulates the immune system and scientific data show that chronic infection with CMV may accelerate the aging of the immune system and lead to subclinical chronic inflammation.
Conclusions: It is important to consider that all individuals over age 60 have their immune system under suspicion and must be treated to minimize interventions that might further compromise the effector functions/ regulating of immune response.
Keywords
Referências
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Submetido em:
02/04/2012
Aceito em:
14/09/2012
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