Flávia Ribeiro

University of Tuebingen, Tübingen, Baden-Württemberg, Germany

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Publications (3)7.09 Total impact

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    ABSTRACT: This chapter summarizes recent work suggesting that human immunosenescence may be closely related to both psychological distress and stress hormones. The age-related immunological changes are also similarly found during chronic stress or glucocorticoid exposure. It follows that endogenous glucocorticoids (cortisol) could be associated to immunosenescence. When compared with young subjects, healthy elders are emotionally distressed in parallel to increased cortisol/ dehydroepiandrosterone (DHEA) ratio. Furthermore, chronic stressed elderly subjects may be particularly at risk of stress-related pathology because of further alterations in glucocorticoid-immune signaling. Although DHEA and its metabolites have been described with immune-enhancing properties, their potential use as hormonal boosters of immunity should be interpreted with caution. The psychoneuroendocrine hypothesis of immunosenescence is presented in which the agerelated increase in the cortisol/DHEA ratio is major determinant of immunological changes observed during aging. We finally discuss that strictly healthy elders are largely protected from chronic stress exposure and show normal cortisol levels and T-lymphocyte function. This information adds a new key dimension on the biology of aging and stress.
    No preview · Article · Jan 2009
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    ABSTRACT: In different inflammatory disease models, heat-shock proteins (hsp) and hsp-derived peptides have been demonstrated to possess anti-inflammatory properties. While some studies have shown that hsp can directly interact with antigen-presenting cells, others report that bacterial hsp can induce specific T cells with regulatory phenotypes. Effective characterization of the immunomodulatory effects of hsp 70, however, has historically been confounded by lipopolysaccharide (LPS) contamination. In this study, we compared the effects of LPS-free Mycobacterial tuberculosis hsp 70 (TBhsp70) and its possible contaminants on dendritic cells (DC). We demonstrate herein that LPS-free TBhsp70 inhibits murine DC maturation in vitro, while LPS-contaminated TBhsp70 induces DC maturation. Mock recombinant preparations have no effect. In contrast to LPS, TBhsp70 does not induce tumour necrosis factor-alpha production by DC, but interleukin-10. In vivo, only LPS-contaminated TBhsp70 induces up-regulation of CD86 in splenic mature DC. Finally, TBhsp70 inhibited phytohaemagglutinin-induced T-cell proliferation. Our results support the hypothesis that TBhsp70 does not have inflammatory potential, but rather has immunosuppressive properties.
    Full-text · Article · Sep 2007 · Immunology
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    ABSTRACT: Ageing of the endocrine system (endocrinosenescence) has been closely related to immunosenescence. Dehydroepiandrosterone sulphate (DHEAS), a steroid hormone produced by the adrenals with reported enhancing immunomodulatory properties, consistently decline during ageing in parallel to detrimental increase in peripheral glucocorticoids. We investigated here the adjuvant effects of DHEAS during intraperitoneal immunization to Mycobacterium tuberculosis heat shock protein 70 (mycHSP70) in old (24 months) as well as young (3 months) BALB/c mice. Both young and old mice had significantly higher Immunoglobulin G (IgG) levels following immunization. Young mice co-immunized with mycHSP70-DHEAS presented an early increase in specific IgG levels and showed increased Interferon-gamma production compared to old mice. Also, T cells of immunized young animals were consistently more resistant to the immunosuppressive effects of glucocorticoids and to DHEAS. DHEAS was not effective in modulating antigen-specific T-cell proliferation, Interleukin-2 production or percentage of recent activated T-cell subsets (CD4 + CD69 + and CD8 + CD69 +). Our data further indicate mycHSP70 as a putative good antigen in vaccine to tuberculosis. Our data also suggest that DHEAS produced adjuvant effects upon humoral and some cellular immune responses of young, but not old mice and indicate that immunization with DHEAS is capable of changing T-cell responses to steroids.
    Full-text · Article · May 2007 · Biogerontology