ABSTRACT
CD4+ T cells regulate humoral and cell-mediated immune responses, which are progressively impaired in aging, resulting in susceptibility to infections and cancer. Dendritic cells (DCs) are major activators of T cells, providing signals that drive their expansion and differentiation. In this study, we asked if decreased CD4+ T cell responses were influenced by the age of DCs rather than being exclusively due to T cell defects. Old T cells transferred to young recipients expanded and differentiated similarly to young T cells. However, aged recipients were poor stimulators of both old and young T cells, which failed to acquire CD44 expression and produce interferon gamma (IFN-γ). DCs in aged hosts expressed fewer MHC-peptide complexes. The CD86 expression in the DCs of both hosts was similar; however, CD40 levels were reduced in old DCs. Finally, old DCs failed to produce inflammatory cytokines in response to LPS. Our results indicate that the impairment of aged CD4+ T cell function is intimately related to multiple alterations in aged DCs, rather than being caused solely by intrinsic T cell defects, suggesting that the function of aged T cells may be partially rescued in vivo when appropriate stimulation is applied. These findings are relevant to vaccination design for elderly populations.
Subject(s)
CD4-Positive T-Lymphocytes/cytology , Dendritic Cells/cytology , Age Factors , Aging , Animals , Antigen Presentation , CD40 Antigens/biosynthesis , Cell Differentiation , Cytokines/metabolism , Hyaluronan Receptors/biosynthesis , Interferon-gamma/metabolism , Lipopolysaccharides/metabolism , Major Histocompatibility Complex , Mice , Mice, Inbred C57BL , Peptides/chemistryABSTRACT
O presente estudo teve como objetivo avaliar a atividade antifúngica do extrato da folha de Psidium guajava Linn. sobre leveduras do gênero Candida, isoladas da cavidade oral, incluindo Candida albicans, C. tropicalis, C. stelatoidea e C. krusei, em análise comparativa com o gluconato de clorexidina à 0,12 por cento. Os ensaios antifúngicos foram realizados pelas técnicas de difusão em meio sólido para a determinação da Concentração Inibitória Mínima (CIM). A CIM do extrato de Psidium guajava sobre C. albicans e C. tropicalis foi de 1:32, C. stelatoidea e C. krusei de 1:2, formando, em média, halos de inibição entre 11 e 22 mm. Diante dos resultados, concluí-se que o extrato da folha de Psidium guajava (goiabeira) apresenta a capacidade de inibir o crescimento de leveduras do gênero Candida da cavidade oral, o que sugere a possibilidade de utilização deste extrato como meio alternativo no tratamento das candidose orais.
The present study evaluated the antifungal in vitro activity of the extract of the leaf of Psidium guajava Linn. against leavens of Candida of the oral cavity, including Candida albicans, C. tropicalis, C. stelatoidea and C. krusei, in comparative study with chlorhexidine (0,12 percent). The tests were carried out by agar-diffusion technique in dishes to determine the Minimum Inhibitory Concentration (MIC). The MIC of the extract of Psidium guajava upon C. albicans and C .tropicalis was 1:32, C. stelatoidea and C. Krusei was 1:2, making, in average, inhibition halos between 11 and 22 mm. It can be concluded that the extract of Psidium guajava show potential to inhibit the growth of leavens of Candida of the oral cavity, it supports the possibility of the use of this extract as an alternative way in the oral candidosis treatment.
