Evidence-based roads to the promotion of health in old age.

The increase in life expectancy, along with the accompanying ongoing increase in the proportion and absolute numbers of nonagenarians and centenarians have set forth the curiosity regarding the question of the quality of health in very old age. Studies on that issue have pointed to the fact that the very old people are actually healthier than originally predicted on the basis of the earlier studies on aging. Current efforts are thus invested in elucidating the possible basis of health in the very old people, as well as better understanding of potential causes of frailty and common diseases in old age. This review recounts on the various aspects underlying evidence-based recommendations for healthy life in old age. We focus on the genetic and non-genetic bases of aging and longevity, and the various directions towards the promotion of health, both via avoiding, or eliminating risk factors and deleterious effects, as well as conducting healthy lifestyle - in terms of proper nutrition and physical exercise. Next, we touch upon preventive medicine, particularly as related to vaccination, with a note also on the need for a reasonable use of medications. In addition, we report about the developing area of regenerative medicine and its potential in relation to the prevention of damage and possible strategies towards tissue repair in cases of age-related degenerative processes.

The center for multidisciplinary research in aging (CMRA) at Ben Gurion University of the Negev in Israel.

The Center for Multidisciplinary Research in Aging (CMRA) was established at Ben Gurion University of the Negev (BGU) in Beer Sheva in 2000, to promote research in the different disciplines of gerontology and geriatrics. It benefits from the special features of that university compared to other academic institutions in Israel and from the regional uniqueness of its location, in the southern part of Israel. CMRA serves as a comprehensive outreach unit for collaborative projects, as well as training programs and organization of professional meetings on aging.

Haematopoietic stem cell ageing.

The question of whether haematopoietic stem cells age has raised considerable controversy, and has been re-opened recently, as a result of the growing interest in stem cells for transplantation and gene therapy. Studies have focused on the generation of different blood cell elements and the capacity for self-renewal; properties that characterize stem cells. Taken together, it appears that basal haematopoiesis is maintained throughout life, yet, the capacity to cope with haematological stress is decreased in advanced age. In principle, stem cells derived from aged donors can be used for autologous transplantation, when needed to recover basic haematopoiesis. However, patterns of T cell development are altered in ageing, and intervention to augment T cell response still needs to be considered. Current methods for expansion and maintenance of stem cells in vitro enable examination of stem cell potential for long-term expansion and function. A critical evaluation of the possible risks of replicative senescence and developmental changes in stem cells has become feasible. Ageing effects may relate to cell replication, cell migration and lymphoid differentiation. Understanding of the mechanisms underlying these processes will enable the fidelity of stem cell expansion and maintenance of their potential for long-term function.

Biogerontology research in Israel.

The article describes the special features of gerontology research that has been expanding for five decades in Israel, and outlines the research in the biology of aging, covering a wide spectrum of areas and topics. A variety of associations, institutes and centers that have been established over the years play an important role in furthering the research and academic training.

Effect of aging on cytokine production in normal and experimental systemic lupus erythematosus-afflicted mice.

Aging mice of strains susceptible to the induction of experimental systemic lupus erythematosus (SLE) develop a milder disease than young animals. To find out whether the decrease in susceptibility to disease is due to age-associated changes in cytokine profile, we first examined the secretion of cytokines by healthy mice aged 2-15 months. A gradual age-related decline in the levels of interleukin (IL)-2 and interferon (IFN) gamma, and an increase in IL-4, IL-10, IL-1, and tumor necrosis factor (TNF) alpha were observed. Experimental SLE was induced in 2- and 10-month-old mice by immunization with the monoclonal anti-DNA antibody bearing the 16/6 Id. Early increased production of pro-inflammatory cytokines (TNFalpha and IL-1), followed by a peak of the Th1-type cytokines (IL-2, IFNgamma) were observed in young mice. The Th2-type cytokines (IL-4, IL-10) peaked later. In contrast, only a mild increase in all of the above cytokines was determined in 10-month immunized mice. It thus appears that the decline in susceptibility to SLE induction in older mice may be related to changes in the capacity to produce cytokines.

Ageing and the mismatch repair system.

Age-related accumulation of mutations has been extensively documented, and it has been proposed as one of the prominent causes of malignancies in old age. The present review is focused on the particular case of DNA mismatch repair system (MMR), that has drawn increased attention for its possible relevance to malignancy. We also report on our own observations on an age-associated genomic instability that develops with age in the MMR system. Our study was performed on DNA samples that were prepared from peripheral blood cells, obtained at a 10-year interval from young and old human subjects. The two DNA samples from each individual were examined comparatively. The older individuals showed a significantly higher rate of microsatellite instability (MSI) in several loci examined, whereas no difference was found between the paired samples of any of the young subjects. We suggest that this increase in MSI with age may indicate an overall genomic instability in the elderly.

Hematopoietic stem cells and aging.

The question of whether hematopoietic stem cells are altered in aging has been the subject of considerable controversy for over two decades. The substantial advancement of knowledge on hematopoietic stem cells and developmental hematology in the last few years has reopened this issue for critical analysis. Dynamic changes have been noted regarding the anatomic site and the function of hematopoietic cells, from the early embryo to old age. Whereas basal hematopoietic potential is maintained in aging. the capacity for recovery from hematological stress and for stem cell self-renewal appears to decline gradually. A distinction is thus made between the steady-state hematopoiesis in aging and the developmental potential of stem cells. The establishment of proper tools to identify and to study purified stem cells and committed cell populations offers a direct approach to further elucidate aging across the axis from primitive stem cells to the mature blood cells. The present article represents a brief review of this area.

Differential effects of CD4+ and CD8+ cells on lymphocyte development from human cord blood cells in murine fetal thymus explants.

The possibility that mature lymphocytes play a role in the regulation of human T cell development was studied in the experimental model of fetal thymus organ cultures (FTOC), by reconstituting lymphocyte-depleted murine fetal thymus (FT) lobe with cells isolated from human umbilical cord blood (CB). Cultures were incubated with human cytokines (IL-7, FLT-3 ligand and Steel Factor), or remained untreated. When CD4+, or CD8+ CB cells, were co-cultured with FT explants, they expanded and maintained their original phenotypic markers, with no significant effect of the cytokines. Cultures of human hematopoietic stem cells (CD34+) gave rise to CD4+CD8- cells, which were mainly CD3-, with no indication of further intermediate developmental stages. However, a limited number of CD4+CD8+ (double positive [DP]) cells were detected when the CD34- cells were co-cultured with CD4+ cells from the same CB samples. In contrast, FT with unseparated CB cells resulted in the different CD4/CD8 subsets, and their numbers increased in the presence of cytokines. The appearance of DP cells depended on the presence of either CD4+ or CD8+ cells in the cultured CB samples. Hence, DP cells were not detected when the CB was depleted of CD4+ and CD8- cells ("depCB") before culture, and they appeared when depCB were co-cultured with either CD4+ or CD8+ cells. In contrast, CD4+ cells inhibited the development of CD8+CD3+ cells, and this was most pronounced in the absence of the cytokines. There was no symmetrical down-regulatory effect of CD8+ cells on the development of CD4+CD3+ cells. Addition of IL-15 to the cytokine mixture led to an increased proportion of CD56+ cells in cultures of CD34+ cells. The presence of CD4+, and not CD8+ cells, interfered with this process. Our results thus imply differential effects of CD4+ and CD8+ cells on thymocytopoiesis.

A possible role for acetylcholine in the dialogue between thymocytes and thymic stroma.

In this article we will review data suggesting that acetylcholine takes part in the mutual interplay between developing T cells and thymic epithelium, and thereby may influence the generation of the T-cell repertoire. In the first part we will recapitulate our findings according to which cholinergic agonists affect thymocyte apoptosis via a nicotinergic effect on thymic epithelial cells. In the second part we will present evidence that acetylcholine within the thymus is mainly derived from the thymocytes themselves, and that the production and release of this neurotransmitter is dependent on activation of thymic lymphocytes.

AlphaMUPA mice: a transgenic model for increased life span.

AlphaMUPA is a line of transgenic mice that, compared with their wild type (WT) counterparts, spontaneously eat less (approximately 20%) and live longer (average approximately 20%), thus resembling dietary-restricted (DR) mice. Here, we show that body temperature was significantly reduced in alphaMUPA compared with WT throughout a wide range of ages. Plasma corticosterone was significantly higher in young alphaMUPA compared to young WT; however, it significantly declined in aged alphaMUPA, but not in aged WT. In addition, age-associated thymus involution occurred in alphaMUPA as it did in WT. Thus alphaMUPA mice appear to largely resemble, but also to somewhat differ from diet-restricted animals. We also report on four new transgenic lines that, like alphaMUPA, produced in the brain the mRNA that encodes the extracellular protease urokinase (uPA); however, transgenic uPA expression was most extensive and widespread in the alphaMUPA brain, where it also occurred in the hypothalamus. AlphaMUPA was also the only line that ate less, but also showed another characteristic, high frequency leg muscle tremor seen only at unstable body states. We hypothesize that transgenic uPA in the brain could have caused the alphaMUPA phenotypic alterations. Thus alphaMUPA offers a unique transgenic model of inherently reduced eating to investigate the homeostatic state of delayed aging at the systemic and single-cell levels.

Estrogen-receptor expression and function in thymocytes in relation to gender and age.

The expression of estrogen receptor (ER) in thymocytes was studied in young, middle-aged, and old (2, 12, and 24 months, respectively) female and male C57BL/6J mice. Western immunoblots prepared from the thymocytes of females of all age groups showed the presence of a 67-kD protein band, which has been associated with the apparent MW of denatured ER. Flow cytometry analysis of cells stained with a monoclonal anti-ER antibody (clone 13H2) disclosed ER expression in both females and males of all age groups. In vivo treatment with estradiol (E2) led to an increase in the specific activity of thymic creatine kinase (CK) in the female mice, whereas the male thymocytes responded with an increase in CK activity only on treatment with dihydrotestosterone (DHT). The data show no differences in ER expression between male and females, but the receptor appears not to be functional in males. Interestingly, when estradiol was applied to co-cultures of lymphoid-depleted fetal thymus (FT) explants and bone-marrow cells, or thymocytes, from young and old females, it resulted in increased cellularity of cultures containing cells of the young, and not those of the old. The proportion of CD4/CD8 phenotypes of the developing cells in these cultures was not affected by E2 treatment. These observations provide a new insight into ER expression and function in T-cell development in relation to gender and age.

MHC-linked syngeneic developmental preference in thymic lobes colonized with bone marrow cells: a mathematical model.

Reconstitution of the T-cell compartment after bone marrow transplantation depends on successful colonization of the thymus by bone-marrow-derived progenitor cells. Recent studies compared the development of syngeneic and allogeneic bone-marrow-derived cells in co-cultures with lymphoid-depleted fetal thymus explants, leading to the discovery of MHC-linked syngeneic developmental preference (SDP) in the thymus. To determine the nature of cell interactions among the bone marrow and thymic elements that might underlie SDP, we analyzed this phenomenon by mathematical modeling. The results indicate that syngeneic mature T cells, responsible for inducing this preference, probably interfere both with the seeding of allogeneic bone-marrow-derived thymocyte progenitors in the thymic stroma and with their subsequent proliferation. In addition, the possibility of augmented death among the developing allogeneic thymocytes cannot be ruled out.

Adrenergic/cholinergic immunomodulation in the rat model--in vivo veritas?

For several years, our group has been studying the in vivo role of adrenergic and cholinergic mechanisms in the immune-neuroendocrine dialogue in the rat model. The main results of these studies can be summarized as follows: (1) exogenous or endogenous catecholamines suppress PBL functions through alpha-2-receptor-mediated mechanisms, lymphocytes of the spleen are resistant to adrenergic in vivo stimulation, (2) direct or indirect cholinergic treatment leads to enhanced ex vivo functions of splenic and thymic lymphocytes leaving PBL unaffected, (3) cholinergic pathways play a critical role in the "talking back" of the immune system to the brain, (4) acetylcholine inhibits apoptosis of thymocytes possibly via direct effects on thymic epithelial cells, and may thereby influence T-cell maturation, (5) lymphocytes of the various immunological compartments were found to be equipped with the key enzymes for the synthesis of both acetylcholine and norepinephrine, and to secrete these neurotransmitters in culture supernatants.

Efficacy of anti-influenza peptide vaccine in aged mice.

Influenza infections may cause serious morbidity, as well as mortality in the elderly. In the present study we vaccinated old and young mice of two strains with three synthetic recombinant constructs (Levi and Arnon, 1995. In: Chanock, R.M. et al. (Eds.), Vaccines 95. CSHL Press, New York, pp. 311-316) and examined their capacity to eliminate a challenge of virus. Virus clearance from the lungs in the aged was very efficient, although the immune response in the aged was comparatively reduced. The data demonstrate that an intranasal administration of peptide-based anti-influenza vaccine without any adjuvant can be efficient and protective in old mice. Further studies are needed to determine whether such constructs will provide an effective vaccine for elderly human subjects.

Checkpoints in thymocytopoiesis in aging: expression of the recombination activating genes RAG-1 and RAG-2.

The study was designed to establish whether the ability to rearrange the T cell receptor (TCR) Vbeta genes is altered with age. We examined the expression of recombinase activating genes, RAG-1 and RAG-2, in the thymus of mice at different ages (2-24 months). A significant age-related decrease in RAG-1 and RAG-2 expression was observed in the thymocytes from the age of 12 months and over. To find out if this decrease is determined in the thymocyte progenitors or induced by the thymic microenvironment, we co-cultured lymphoid depleted fetal thymus (FT) explants with bone marrow cells, or immature thymocytes, from young and old mice. The developing thymocytes were examined at different time intervals during the first week of culture. Whereas cells derived from the immature thymocytes of the old donors failed to express RAG-1 and RAG-2, compared to the young, the bone marrow derived cells of both age groups did show this expression, and there was no difference in Vbeta rearrangement of the TCR. Our study indicates that T cell progenitors in the aging bone marrow retain the potential to give rise to T cells with TCR rearrangements, and the expression is determined by the thymic stroma.

Effect of aging on cytokine production in normal and experimental systemic lupus erythematosus afflicted mice.

The objective of the this study was to determine the cytokine profile of aging mice and to establish whether changes in cytokine production account for the fact that aging mice develop a milder disease than the young in response to induced experimental systemic lupus erythematosus (SLE). Cytokine secretion was evaluated in groups of BALB/c and C3H.SW mice at different ages between 2 and 24 months. The production of IL-2, IL-4, IL-10, IFN gamma and TNF alpha was determined in supernatants of ConA-stimulated splenocytes and that of IL-1 in the supernatants of LPS-stimulated peritoneal macrophages. A gradual age-related decline was observed in the production of IL-2 and IFN gamma, whereas the levels of IL-4, IL-10, IL-1 and TNF alpha progressively increased with aging, in unimmunized BALB/c and C3H.SW mice. Experimental SLE was induced in 2 and 10 month old C3H.SW mice by immunization with the monoclonal anti-DNA antibody bearing the 16/6 Id. The characteristic cytokine profile following immunization of 2 month old mice was early increased production of TNF alpha and IL-1, followed by a peak of Th1 type cytokines (IL-2, IFN gamma). At a later stage of the disease, a peak of Th2 type cytokines (IL-4, IL-10) was observed that was concomitant with low levels of Th1 cytokines. In contrast, in the 10 month old mice that were immunized with 16/6 Id only a mild increase in all the above cytokines was observed. We suggest that the lower autoantibody production and moderate clinical manifestations in aging mice with experimental SLE are causally related to the decreased production of pro-inflammatory cytokines at the initial stages of the disease followed by a lower production of both Th1 and Th2 type cytokines.