Ageing is associated with several anatomical and physiological changes of the organism, and the increase in global elderly population promotes the research to develop strategies to improve their quality of life. In this work, we characterized the immunological alterations naturally produced during aging in a mice model, and evaluated the effect of probiotic Lactobacillus (L.) rhamnosus CRL1505 administration on those immunological parameters. We demonstrated that L. rhamosus CRL1505 was able to improve peritoneal macrophages phagocytic activity, and the number of intestinal IgA + cells in aged mice, reaching values of those parameters similar to young adult mice. The results of this work indicate that is plausible that the immunobiotic CRL1505 strain may find applications as a beneficial immunomodulator in aging to reinforce the intestinal and systemic immunity. The immune modulation in aging induced by L. rhamnosus CRL1505 could lead to the development of new strategies for functional foods specifically tailored for the elderly.
Aging is a manifold of universal biological processes that profoundly alter anatomy and physiology of all organisms. Substantial increases in the relative and absolute number of older persons in our societies have posed a challenge for medicine, as successful aging is multidimensional for maintaining high physical and cognitive function for sustained engagement in social and productive activities. A key factor is the maintenance of normal immune functions to provide immediate response to pathogens and to integrate and influence the adaptive immune response [
Functional probiotic foods have been shown to have several beneficial effects in elderly subjects including the reduction of constipation, modulation of serum cholesterol levels, improvement of the balance of intestinal flora, and immunomodulatory activities [
We have previously reported that Lactobacillus (L.) rhamnosus CRL1505, strain isolated from goat milk, has probiotic properties. Studies in mice models show that administration of CRL1505 strain enhances the resistance against intestinal and respiratory pathogens in infant and young adult mice, improving both systemic and mucosal immune responses [
The effect of probiotics may be different according to the physiological state of the subjects. This suggests that for aging studies, it is imperative to analyse probiotic effects in appropriate experimental models of aged subjects rather than extrapolating results from studies on young adult population. From these considerations, this study is undertaken to find out whether the immunobiotic L. rhamnosus CRL1505 exerts beneficial effects in aged hosts.
L. rhamnosus CRL1505 (culture collection CERELA, Tucumán, Argentina) was grown independently in a milk-based culture medium added with sugar and salts (under patent) for bulk biomass production. Batch fermentations were carried out in a 2.5L-bioreactor (Infors HT, Switzerland) at 37˚C and pH 5.5 for 22 h. Bacteria were harvested and washed twice (sterile saline solution) by centrifugation (7000× g, 10 min, 4˚C) and suspended in 40% (w/v) reconstituted skim milk (RSM) containing 5% (w/v) food grade monosodium glutamate. The cell suspension was spray-dried (Buchi B-290, Switzerland) and the inmunobiotic powder obtained was stored at −20˚C before using.
Female BALB/c aged mice (64-weeks old) were obtained from the closed colony of the breeding unit kept at CERELA Institute (San Miguel de Tucumán, Argentina) housed in plastic cages and maintained at 20 ± 2˚C with a 12-h light/dark cycle. Animal studies and protocols were approved by the CERELA Ethical Committee of Animal Care with the identification CRL-BIOT-LTD-2008/1A.
Mice were randomly allocated to four main experimental groups as follows: EBc group (Elderly Basal control group) elderly mice that received water ad libitum; EM group (Elderly Milk group) elderly mice that received RSM ad libitum; E-1505 group (Elderly + 1505 group) elderly mice that received L. rhamnosus CRL1505; YB group (Young Basal) young mice (mice 6-weeks old) that received water ad libitum. This last group was used as reference but not as control group. All groups were allowed free access to the conventional balanced diet. L. rhamnosus CRL1505 was administered to E-1505 group at 108 cells/mouse/day in RSM during 7 consecutive days.
Peritoneal macrophages were obtained as described previously [
The small intestines were removed and washed with saline solution (NaCl 0.15 M). Tissues were prepared according to Vinderola et al. [
Experiments were performed in triplicate and results were expressed as means ± SD. Statistical analysis was conducted using MINITAB software (version 15 for Windows). 2-factor ANOVA was used to test the effects of experimental group, time, and their interaction. Tukey’s post hoc test was used to test for differences between the mean values. Significance was set at P < 0.05.
Immune functions are known to deteriorate with age in several species, a process known as immunosenescence. In humans, the elderly are at a higher risk for infections and the immune response to vaccination is diminished [
As observed in
group) (18 ± 1.0%) compared to young mice (YBc group) (29 ± 1.8%). Administration of milk to EM group did not induce any significant change in these parameters (20 ± 1.3%) while an increase in the aged group fed the immunobiotic CRL1505 strain (E-1505 group) (29 ± 1.1%) was observed, reaching values similar to the young mice.
The monocytes/macrophage system is an essential cellular part of the innate immune response. These cells play important functions to control microorganisms and are the link to the adaptive immune system via their role in antigen presentation. There is clear evidence that phagocytosis and killing capacities of macrophages are also reduced with age, due to lower production of reactive oxygen species (ROS) such as NO2 and H2O2 [
(86 ± 3.0 cells/10 fields). Administration of milk to EM group did not induce any significant change in IgA+ cells (66 ± 1.9 cells/10 fields) while an increase in the aged group fed the immunobiotic CRL1505 strain, E-1505 (81 ± 2.8 cells/10 fields) was observed, with values similar to the young mice.
The intestinal tract in the elderly is particularly susceptible to infectious diseases suggesting that a poor mucosal immunity is a major factor leading to higher mortality from infections in aging [
There is significant evidence showing that several physiological functions are altered by advanced aging, and that some probiotic strains are able to reduce some of those alterations. The results of this work indicate that is plausible that the immunobiotic strain L. rhamnosus CRL1505 may find applications as a beneficial immune- omodulator in aging to reinforce the intestinal and systemic immunity. The immune modulation in aging induced by L. rhamnosus CRL1505 could lead to the development of new strategies for functional foods specifically tailored for the elderly.
This study was carried out with the financial support from CONICET (PIP0406/12) and MinCyT (PICT2011 N˚0175) from Argentina.
Verónica Molina,Marta Médici,Julio Villena,Graciela Font,María Pía Taranto, (2016) Dietary Supplementation with Probiotic Strain Improves Immune-Health in Aged Mice. Open Journal of Immunology,06,73-78. doi: 10.4236/oji.2016.63008