[Show abstract][Hide abstract]ABSTRACT: Prospective studies have indicated an age-related impairment of the immune response. Carotenoids have been hypothesised to enhance immune cell function. The aim of the present study was to describe the age-related effects and the impact of in vivo dietary carotenoid depletion and repletion on specific and non-specific immunity. A total of ninety-eight healthy male subjects (aged 20-75 years) received a carotenoid-depleted diet for 3 weeks and were then supplemented daily for 5 weeks with 30 mg β-carotene, 15 mg lycopene and 9 mg lutein. Blood samples were collected at study entry, after depletion and supplementation, and biomarkers of immune status were determined. We found that serum IgA levels were positively correlated with ageing. Lymphocyte phenotyping indicated an increase with age in the memory T-helper cell subpopulation (CD4+CD45RO+) concomitantly with a decrease in naive T-helper cells (CD4+CD45RA+). A significant increase in the natural killer cells subpopulation and a small decrease in B lymphocytes were also observed, especially for the oldest volunteers. From ex vivo cell function exploration, a positive correlation was observed between age and IL-2 production of phytohaemagglutinin-stimulated lymphocytes. Neutrophils' bactericidal activity was significantly impaired with age (from 50 years) and was modulated by carotenoid status. An age effect was found on neutrophils' spontaneous migration but not on directed migration. Immune response in healthy human subjects is mostly affected by age rather than by dietary carotenoid depletion and repletion. Even in carefully selected healthy volunteers, some age-related immune changes occur predominantly from 50 years onwards. This immunosenescence could generate a loss in the immune system adjustment capacity.
Preview · Article · Mar 2012 · The British journal of nutrition
[Show abstract][Hide abstract]ABSTRACT: The immune system gradually deteriorates with age and nutritional status is a major factor in immunosenescence. Of the many nutritional factors implicated in age-related immune dysfunction, vitamin A may be a good candidate, since vitamin A concentrations classically decrease during aging whereas it may possess important immunomodulatory properties via its active metabolites, the retinoic acids. This prompted us to investigate the immune response induced by retinoids in adults and elderly healthy subjects. Before and after oral supplementation with 13cis retinoic acid (0.5 mg/kg/day during 28 days), whole blood cells were phenotyped, and functions of peripheral blood mononuclear cells (PBMC) and polymorphonuclear cells (PMN) were investigated by flow cytometry and ELISA tests.
In both young adults (n = 20, 25 ± 4 years) and older subjects (n = 20, 65 ± 4 years), retinoic acid supplementation had no effect on the distribution of leukocyte subpopulations or on the functions of PBMC (Il-2 and sIl-2R production, membrane expression of CD25). Concerning PMN, retinoic acid induced an increase in both spontaneous migration and cell surface expression of CD11b in the two different age populations, whereas bactericidal activity and phagocytosis remained unchanged.
We demonstrated that retinoic acid induces the same intensity of immune response between adult and older subjects, and more specifically affects PMN functions, i.e. adhesion and migration, than PBMC functions.
Full-text · Article · Aug 2010 · Immunity & Ageing
[Show abstract][Hide abstract]ABSTRACT: Prospective studies indicate that tomato consumers are protected against prostate cancer. Lycopene has been hypothesized to be responsible for tomato health benefits.
Our aim was to differentiate the effects of tomato matrix from those of lycopene by using lycopene-rich red tomatoes, lycopene-free yellow tomatoes, and purified lycopene.
Thirty healthy men (aged 50-70 y old) were randomly assigned to 2 groups after a 2-wk washout period. In a crossover design, each group consumed yellow and red tomato paste (200 g/d, which provided 0 and 16 mg lycopene, respectively) as part of their regular diet for 1 wk separated by 2 wk of washout. Then, in a parallel design, the first group underwent supplementation with purified lycopene (16 mg/d) for 1 wk, whereas the second group received a placebo. Sera collected before and after the interventions were incubated with lymph node cancer prostate cells to measure the expression of 45 target genes.
Circulating lycopene concentration increased only after consumption of red tomato paste and purified lycopene. Lipid profile, antioxidant status, prostate-specific antigen, and insulin-like growth factor I were not modified by consumption of tomato pastes and lycopene. We observed significant up-regulation of IGFBP-3 and Bax:Bcl-2 ratio and down-regulation of cyclin-D1, p53, and Nrf-2 after cell incubation with sera from men who consumed red tomato paste when compared with sera collected after the first washout period, with intermediate values for yellow tomato paste consumption. Cell incubation with sera from men who consumed purified lycopene led to significant up-regulation of IGFBP-3, c-fos, and uPAR compared with sera collected after placebo consumption.
Dietary lycopene can affect gene expression whether or not it is included in its food matrix. This trial was registered by the French Health Ministry at http://www.sante-sports.gouv.fr as 2006-A00396-45.
Full-text · Article · Jun 2010 · American Journal of Clinical Nutrition
[Show abstract][Hide abstract]ABSTRACT: The regulation of cell growth and differentiation and also expression of a number of genes by retinoids are mediated by nuclear retinoid receptors (RARs and/or RXRs). In this study we investigated age-related alteration in both RAR and RXR receptor subtypes gene expression and tissue transglutaminase (tTG) activity before and after supplementation with 13-cis retinoic acid (13cRA) in human peripheral blood mononuclear cells (PBMCs). Healthy men (40) were divided in two groups according to their age (young group: 26.1+/-4.1 years and old group: 65.4+/-3.8 years). Each volunteer received 13cRA (Curacné), 0.5mg/(kgday)) during a period of 4 weeks. We have shown that RXRbeta expression was decreased significantly (p=0.0108) in PBMCs of elderly men when compared to that of young volunteers. Distribution of retinoic acid receptor subtype expression in PBMCs was found in the order: RXRbeta>RARgamma>RXRalpha>RARalpha. The tTG activity in PBMCs reflected a trend to be enhanced after 13-cis retinoic acid supplementation. In conclusion, we demonstrate a significant decrease in the expression of RXRbeta subtype of rexinoid receptors in PBMCs of healthy elderly men. Our data suggest that in healthy elderly men reduction of RXRbeta expression in PBMCs might be a common feature of physiological senescence.
Full-text · Article · Nov 2007 · Mechanisms of Ageing and Development
[Show abstract][Hide abstract]ABSTRACT: The primary role of polymorphonuclear neutrophils (PMNs) is to destroy pathogenic microorganisms after phagocytosis by producing reactive oxygen species (ROS) and toxic molecules. However, PMNs produce sufficient amounts of ROS during an oxidative burst to be autotoxic and detrimental to their own functions and to possibly cause DNA damage, protein and lipid oxidation and cell membrane destructuration.
The aim of this study was to investigate in vivo the role of the antioxidant capacities of carotenoids in modulating ROS content in PMNs during oxidative burst. Moreover to investigate the direct or indirect effect of carotenoids, the modification of PMN ROS content was explored after in vitro supplementation with beta-carotene or lycopene, chosen taking account of their vitamin A and no vitamin A precursor effect, respectively.
In vivo study: Venous blood was collected from 10 healthy male volunteers and ROS production from phorbol myristate acetate (PMA)-stimulated PMNs was determined, by flow cytometry using the fluorescent dye dihydrorhodamine 123, at baseline, after 3 weeks of carotenoid depletion (carotenoid intake limited to 25% of usual intake) and after 5 weeks of carotenoid repletion (30 mg beta-carotene, 15 mg lycopene and 9 mg lutein per day). In vitro study: ROS content in PMA-stimulated PMNs isolated from carotenoid depleted subjects and controls was quantified after an in vitro enrichment with beta-carotene (1 micromol/L) or lycopene (0.3 micromol/L).
In vivo carotenoid depletion increased PMN H2O2 content after PMA activation by 38% (p < 0.05 vs baseline),while supplementation for 5 weeks restored basal H2O2 generation (p < 0.05 vs depletion). Although H2O2 measurement in PMNs from non-depleted subjects was not affected by an in vitro supply with beta-carotene or lycopene, a significant decrease in H2O2 content by 78.9 % and 81.2%, respectively, was observed in PMNs from carotenoid depleted subjects (p < 0.01 vs depleted control subjects).
The carotenoid ROS quenching capacities control both in vivo and in vitro the PMNs ROS generation and probably protect these cells against DNA, membrane lipid and protein damages during oxidative burst. Moreover, these effects appear independent from the metabolic conversion of carotenoids to vitamin A.
No preview · Article · Apr 2005 · European Journal of Nutrition
[Show abstract][Hide abstract]ABSTRACT: An impairment of muscle glutamine metabolism in response to dexamethasone (DEX) occurs with aging. To better characterize this alteration, we have investigated muscle glutamine release with regard to muscle glutamine production (net protein breakdown, de novo glutamine synthesis) in adult and old glucocorticoid-treated rats. Male Sprague-Dawley rats (3 or 24 mo old) were divided into seven groups: three groups received 1.5 mg/kg of DEX once a day by intraperitoneal injection for 3, 5, or 7 days; three groups were pair fed to the three treated groups, respectively; and one control group of healthy rats was fed ad libitum. Muscle glutamine synthetase activity increased earlier in old rats (day 3) than in adult rats (day 7), whereas an increase in muscle glutamine release occurred later in old rats (day 5) than in adult DEX-treated rats (day 3). Consequently, muscle glutamine concentration decreased later in old rats (day 5) than in adults (day 3). Finally, net muscle protein breakdown increased only in old DEX-treated rats (day 7). In conclusion, the impairment of muscle glutamine metabolism is due to a combination of an increase in glutamine production and a delayed increase in glutamine release.
Full-text · Article · Nov 2004 · AJP Endocrinology and Metabolism
[Show abstract][Hide abstract]ABSTRACT: Various alterations of aminoacidemia have been described during breast cancer. The aim of this study was first to establish the specific modifications of plasma-free amino acid concentrations by a comparative study of 19 patients with mammary tumors and 18 healthy volunteers, and, second, to determine the evolution of aminoacidemia after surgical tumor removal. Aminoacidemia was determined the day before (D0), and then five days, one month (M1), and six months after surgical removal of the tumor, and a single determination was performed in control subjects. Plasma levels (mumol/L) of serine and glutamate were higher in cancer-bearing women at D0 (respectively, 124 +/- 3 and 68 +/- 7) than in healthy volunteers (respectively, 110 +/- 6 and 48 +/- 5). Surgical tumor removal induced a normalization of aminoacidemia (in mumol/L at D5: serine: 114 +/- 4; at M1: glutamate: 55 +/- 6 Non Significant (NS) from values of healthy subjects). Among the various patterns reported for breast cancer, we confirm one of those described by Cascino in 1995, and we show that these levels revert to normal after tumor surgical removal.
No preview · Article · Feb 2004 · Cancer Investigation
[Show abstract][Hide abstract]ABSTRACT: Aging brings poor adaptation to stress, the causes of which remain unclear. We previously reported impairment of nitrogen metabolism in glucocorticoid-treated old rats due to profound anorexia. Here we investigated whether leptin, a satiety hormone, was implicated in impaired adaptation to stress. Plasma glucose and insulin levels, which are known to modulate leptin secretion, were also studied. Adult (3 months, n = 18) and aged (24 months, n = 18) rats were treated with dexamethasone (DEX) (1.5 mg/kg/d, intraperitoneal [IP] injection) for 3, 5, and 7 days. Results were compared with ad libitum (n = 12) and pair-fed groups, receiving intraperitoneal saline injection, for each age (n = 6 per group). Transitory anorexia was observed in adult rats (day 3 to day 5), whereas anorexia persisted in aged rats until day 7. This anorexia was associated (r = -.65, P <.05) with an elevated constant hyperleptinemia. In contrast, hyperleptinemia was moderate and reverted rapidly to basal values by day 5 in adult rats. The time course of plasma insulin and glucose levels was similar in old and adult rats, except for marked hyperglycemia noted in aged animals. In old stressed rats, DEX treatment induces an anorexia, which is concomitant to an increase in serum leptin levels. Thus, leptin may be implicated in the poor adaptation to stress of aged compared with adult rats.
[Show abstract][Hide abstract]ABSTRACT: Daily injections of dexamethasone (DEX) given to adult rats are a recognized but nonstandardized model of stress. The aim of this work was to establish a reproducible and accurate model of stress in adult rats by chronic injection of DEX in order to standardize it. For this purpose, the effect of the duration of treatment and the effect of DEX dose were tested. To help understand the mechanisms of the catabolic effect of DEX, the study was extended to the metabolism of glutamine (GLN). In experiment 1, 60 male Sprague-Dawley rats (3 months old) were divided into 8 groups of 6 rats: groups G3, G5, G7, and G9 received 1.50 mg/kg/d of DEX by intraperitoneal (i.p.) injection for 3, 5, 7, or 9 days, respectively. Groups G3PF, G5PF, G7PF, or G9PF were pair-fed to groups G3, G5, G7, or G9, respectively. Group AL (n = 12) was healthy rats fed ad libitum.
In treated rats, nitrogen balance reached its lowest value at day 5. After 9 days treatment by DEX, the catabolic state was reduced. An increase in GLN-synthetase activity and a decrease in muscle GLN content were related to DEX per se not to DEX-induced anorexia. In experiment 2, 25 rats were divided into 5 groups of 5 animals. Groups G0.75, G1.50, and G2.50 received 0.75, 1.50, and 2.50 mg/kg/d, respectively, of DEX by i.p. injection for 5 days. Group PF was pair-fed to group G2.50 and group AL was control rats.
DEX induced a decrease in nitrogen balance that was dose-independent. GLN-synthetase activity was increased maximally in gastrocnemius by 0.75 mg/kg.
Five days of treatment by DEX and a dose of 0.75 mg/kg/d induced a marked catabolic state.
Full-text · Article · Jan 2000 · Journal of Parenteral and Enteral Nutrition
[Show abstract][Hide abstract]ABSTRACT: Aged rats are more sensitive to injury, possibly through an impairment of nitrogen and glutamine (Gln) metabolisms mediated by glucocorticoids. We studied the metabolic kinetic response of adult and old rats during glucocorticoid treatment. The male Sprague-Dawley rats were 24 or 3 mo old. Both adult and old rats were divided into 7 groups. Groups labeled G3, G5, and G7 received, by intraperitoneal injection, 1.50 mg/kg of dexamethasone (Dex) for 3, 5, and 7 days, respectively. Groups labeled G3PF, G5PF, and G7PF were pair fed to the G3, G5, or G7 groups and were injected with an isovolumic solution of NaCl. One control group comprised healthy rats fed ad libitum. The response to aggression induced specifically by Dex (i.e., allowing for variations in pair-fed controls) appeared later in the aged rats (decrease in nitrogen balance from day 1 in adults but only from day 4 in old rats). The adult rats rapidly adapted to Dex treatment, whereas the catabolic state worsened until the end of treatment in the old rats. Gln homeostasis was not maintained in the aged rats; despite an early increase in muscular Gln synthetase activity, the Gln pool was depleted. These results suggest a kinetic impairment of both nitrogen and muscle Gln metabolisms in response to Dex with aging.
Full-text · Article · Apr 1999 · The American journal of physiology
[Show abstract][Hide abstract]ABSTRACT: Increase in life expendancy and global aging of the population have led to increased interest in the aging process. A better understanding of aging-related modifications of meta-bolism is needed. For example, aging is an independent risk factor in critically ill patients. Allowing for illnesses whose frequency increases with age (obesity, NIDDM, cardiovascular disease), this may result from impaired metabolic response to hormones. This review present the current literature data concerning the evolution of the responsiveness to anabolic (insulin) and catabolic hormones (glucagon, glucocorticoids, catecholamines and thyroid hormones) with aging. Although some studies indicate a decrease in the responsiveness to various hormones, these modifications are moderate and their consequences are difficult to ascertain given the influence of confounding factors such as abnormal energy metabolism linked to dietary habits and life-style.
No preview · Article · Oct 1998 · Nutrition Clinique et Métabolisme