Aging and immune function

Changes of CD4+CD25+Foxp3+ regulatory T cells in aged Balb/c mice

A progressive decline in the integrity of the immune system is one of the physiologic changes during aging. The frequency of autoimmune diseases or immune disorders increases in the aging population, but the state of regulatory T (Treg) cells in aged individuals has not been well determined. In the present study, we investigated the levels, phenotypes, and function of CD4(+)CD25(+) Treg cells in Balb/c mice, which were older than 20 months. Significantly enhanced percentages of CD4(+)CD25(+) Treg cells in the periphery (blood, spleen, and lymph nodes) of the aged mice were observed. These Treg cells showed modified Vbeta family distribution, reduced levels of CD45 receptor B and CD62 ligand molecules, as well as normal levels of forkhead box p3. However, when the inhibiting function of Treg cells was assayed in the in vitro assays and in a delayed-type hypersensitivity (DTH) model, CD4(+)CD25(+) Treg cells of aged mice displayed significantly lower inhibiting ability on alloantigen-induced DTH reaction or cytokine productions (IL-2 and IFN-gamma) but not cell proliferation of effector T cells, as compared with CD4(+)CD25(+) Treg cells of young mice. In addition, the percentages of CD4(+)CD8(-)CD25(+) Treg cells in the thymi of aged mice increased significantly, but their total cell numbers decreased markedly in these mice. Our present studies indicated collectively that the percentages, phenotypes, the size of TCR repertoire, and function of CD4(+)CD25(+) Treg cells were altered significantly with aging in mice. The functional defects of CD4(+)CD25(+) Treg cells may shed light on the role of CD4(+)CD25(+) Treg cells in the increased sensitivity to autoimmune diseases of aged populations.

Advanced age exacerbates the pulmonary inflammatory response after lipopolysaccharide exposure

OBJECTIVE

The aged population is at a higher risk of mortality as a result of complications of injury or infection, such as acute lung injury. The objective of this study was to analyze pulmonary inflammatory responses in young and aged mice after administration of lipopolysaccharide.

DESIGN

Prospective, controlled laboratory study.

SETTING

Animal resource facilities and research laboratory.

SUBJECTS

Young (2-3 months old) and aged (18-20 months old) female BALB/c mice.

INTERVENTIONS

Animals received intraperitoneal injection of lipopolysaccharide derived from Pseudomonas aeruginosa. Control mice received saline alone. After 24 hrs, mice were killed. Pulmonary neutrophil infiltration was assessed histologically and by myeloperoxidase activity. Pulmonary levels of the CXC chemokines, monocyte inflammatory protein-2 and KC, and cytokines, tumor necrosis factor-alpha and interleukin-1beta, were assessed by enzyme-linked immunosorbent assay.

MEASUREMENTS AND MAIN RESULTS

Lungs of aged mice given lipopolysaccharide showed a six-fold higher neutrophil infiltration and three-fold higher level of myeloperoxidase activity than lungs of young mice given lipopolysaccharide. Pulmonary levels of monocyte inflammatory protein-2 and KC were significantly higher in the lungs of aged mice given lipopolysaccharide, compared with younger mice. Levels of tumor necrosis factor-alpha and interleukin-1beta in the lung were analyzed as well. After lipopolysaccharide treatment, there was no difference in the level of tumor necrosis factor-alpha in lungs of young and aged animals, but interleukin-1beta was two-fold higher in the lungs of the aged group. These data suggest that at this time point, interleukin-1beta may contribute to the higher production of CXC chemokines observed in lungs of aged mice vs. young mice receiving lipopolysaccharide.

CONCLUSIONS

The hyperreactive systemic inflammatory response seen in aged individuals after lipopolysaccharide administration is accompanied by an exacerbated pulmonary inflammatory response, which may contribute to the higher mortality seen in the aged given an inflammatory insult.

Aging and CD8+ T cell immunity to respiratory virus infections

The capacity of the immune system to mediate effective immune responses to pathogens declines with age. In the case of immune responses to newly encountered antigens, several studies have demonstrated that this decline reflects both a loss of naïve T cells and changes in the repertoire and function of these cells over time. However, comparatively little is known about the impact of age on established memory T cells pools. Here we discuss age-related changes in memory CD8(+) T cell pools elicited by influenza and parainfluenza viruses and the impact of these changes on immunity in general.

Do Langerhans cells behave similarly in elderly and younger patients with chronic periodontitis?

OBJECTIVE

The purpose of this study was to compare the number, the distribution and the expression of markers of maturation of Langerhans cells (LC) in elderly and younger patients with chronic periodontitis in order to evidence the effect of aging on LC in inflammatory gingival tissue.

METHODS

Gingival tissue specimens presenting chronic periodontitis from 8 elderly patients aged >75 (group E) and from 8 younger patients aged 50-60 (considered as controls, group C) were used for immunohistochemistry with monoclonal antibodies against CD45RB (leucocytes), CD1a (LC), markers of LC maturation (DC-LAMP, CD83) and number of immunolabelled cell subsets was evaluated using image analysis.

RESULTS

The difference in the number of CD45RB+ leucocytes in the upper connective tissue between groups was not significant. In group E, the number of CD1a+ LC was significantly decreased (P<0.002) in the epithelium and significantly increased (P<0.0004) in the upper connective tissue. Furthermore, in group E, intraepithelial CD1a+ LC are more often observed in the upper epithelium and their dendritic processes were shorter and less numerous. Concerning the expression of markers of maturation, the numbers of intraepithelial DC-LAMP+ cells and CD83+ cells were significantly increased (P<0.0007 and P<0.02, respectively) in group E.

CONCLUSION

During chronic periodontitis in elderly patients, the decrease in the number of intraepithelial LC and the alteration of dendritic processes could be balanced by a cellular distribution often observed in the upper epithelium associated with changes in cell maturation in response to bacterial elements.

Diversity of the Ig Repertoire is Maintained With Age In Spite of Reduced Germinal Centre Cells in Human Tonsil Lymphoid Tissue

Humans and almost all species studied to date exhibit a decreased responsiveness to immunization and increased autoimmunity with age. While this has been observed clinically for decades, only recently has an understanding of the molecular basis for these changes begun to be appreciated. Studies of the B-cell aspects of these changes in ageing mice and the very few reports in ageing humans have not been conclusive. Here we examine the nucleotide sequence of over 1250 VH transcripts from the tonsils of individuals of various ages for changes to the VH4 immunoglobulin repertoire. An exhaustive examination of VH, DH and JH gene segment utilization revealed a remarkable similarity of the repertoires. The extent of somatic hypermutation was fully maintained or even increased by some measures into the eighth decade of life. However, we found by middle age that the representation of naïve and germinal centre B-cell subpopulations changed relative to total B lymphocytes in the tonsil. While the percentage of naïve and germinal centre B-cell subpopulations changes during the second half of life, these findings suggest that even with advancing age, humans remain capable of generating an extremely diverse Ig repertoire while maintaining a similar spectrum of Ig rearrangements once the germinal centre reaction begins.

Immunity and age: living in the past?

Increasing age is associated with a decreasing ability to mediate effective immune responses to newly encountered antigens. It is generally believed that this reflects the age-associated decline in the number, repertoire and function of available naive T cells. Here, we propose that naive T cells become increasingly irrelevant to the immune system, and that responses to newly encountered antigens are progressively dominated by cross-reactive memory T cells as the individual ages. In addition, we propose that the majority, if not all, of the response to newly encountered antigens in the elderly is mediated by cross-reactive memory T cells. This predicts highly stochastic responses to new infections that should vary between individuals, and has important implications for vaccination strategies in the elderly.

Oral tolerance

Multiple mechanisms of tolerance are induced by oral antigen. Low doses favor active suppression, whereas higher doses favor clonal anergy/deletion. Oral antigen induces T-helper 2 [interleukin (IL)-4/IL-10] and Th3 [transforming growth factor (TGF)-beta] T cells plus CD4+CD25+ regulatory cells and latency-associated peptide+ T cells. Induction of oral tolerance is enhanced by IL-4, IL-10, anti-IL-12, TGF-beta, cholera toxin B subunit, Flt-3 ligand, and anti-CD40 ligand. Oral (and nasal) antigen administration suppresses animal models of autoimmune diseases including experimental autoimmune encephalitis, uveitis, thyroiditis, myasthenia, arthritis, and diabetes in the non-obese diabetic (NOD) mouse, plus non-autoimmune diseases such as asthma, atherosclerosis, graft rejection, allergy, colitis, stroke, and models of Alzheimer's disease. Oral tolerance has been tested in human autoimmune diseases including multiple sclerosis (MS), arthritis, uveitis, and diabetes and in allergy, contact sensitivity to dinitrochlorobenzene (DNCB), and nickel allergy. Although positive results have been observed in phase II trials, no effect was observed in phase III trials of CII in rheumatoid arthritis or oral myelin and glatiramer acetate (GA) in MS. Large placebo effects were observed, and new trials of oral GA are underway. Oral insulin has recently been shown to delay onset of diabetes in at-risk populations, and confirmatory trials of oral insulin are being planned. Mucosal tolerance is an attractive approach for treatment of autoimmune and inflammatory diseases because of lack of toxicity, ease of administration over time, and antigen-specific mechanisms of action. The successful application of oral tolerance for the treatment of human diseases will depend on dose, developing immune markers to assess immunologic effects, route (nasal versus oral), formulation, mucosal adjuvants, combination therapy, and early therapy.

Modulation of neuropeptide Y and norepinephrine on several leucocyte functions in adult, old and very old mice

The age-related changes in the communication between the nervous and the immune system have been scarcely investigated, especially in very aged subjects. The present work deals with the in vitro effects of norepinephrine and neuropeptide Y, separately and jointly, on functions such as lymphoproliferation, NK activity, and IL-2 and TNF-alpha release of peritoneal leucocytes from adult (24+/-2 weeks), old (72+/-2 weeks) and very old (128+/-2 weeks) mice. The old mice showed a decrease in proliferation, NK activity and IL-2 release, and an increase in TNF-alpha, whereas in the very old mice these functions were more similar to those of the adults. The effects of neurotransmitters on these functions were different depending on the age of the animals.

Changes with ageing in several leukocyte functions of male and female rats

The impairment of the immune system with aging, or 'immunosenescence', appears to contribute to the increased morbidity and mortality of aged subjects. T cell functions and Natural Killer activity seem to be the immune responses most affected by ageing. Since the immune system works more efficiently in females than in males, we have studied the changes of several immune functions with age in rats of both sexes. In addition, we have investigated if ovariectomy, a model of menopause in rats, produces a loss of this gender-related advantage. In the present work, the changes with age (2, 6, 12, 14, 18, 22 and 24 months old) in lymphocyte chemotaxis, T lymphoproliferative response to the mitogen ConA, IL-2 release and Natural Killer activity of cells from axillary nodes and spleen of male and female rats as well as of females ovariectomized at 12 months of age have been studied. An age-related decrease was found in all investigated functions, with a slightly different evolution depending on the immune organ and gender considered. In general, the data obtained show that a certain degree of immunosenescence takes place with age in rats, with males being less immunocompetent than intact age-matched females, but showing an immune response similar to that of ovariectomized animals.

The Use of Dehydroepiandrosterone Therapy in Clinical Practice

Dehydroepiandrosterone (DHEA) therapy is controversial due to sensationalized reports of epidemiologic studies and the over-the-counter availability of DHEA. Human clinical trials have investigated the potential efficacy of DHEA therapy in multiple conditions with resultant inconsistencies in findings. DHEA is unique compared with other adrenal steroids because of the fluctuation in serum levels found from birth into advancing age. The lower endogenous levels of DHEA and DHEA sulfate found in advancing age have been correlated with a myriad of health conditions. Also, some studies suggest gender-specific actions of endogenous and exogenous DHEA. We reviewed only pharmacokinetic studies and human clinical trials investigating the efficacy of DHEA therapy that were placebo-controlled as these provided the most reliable scientific basis for the evaluation of DHEA therapy. Pharmacodynamic studies suggest that doses of 30-50mg of oral DHEA may produce physiologic androgen levels, especially in women. These studies report a dose-dependent effect and lack of accumulation of serum androgen levels. Pharmacologic studies also reveal a gender-specific response to DHEA therapy such that testosterone levels are increased in women but not in men. Clinical trials suggest that 50mg of oral DHEA, but not <30mg, can increase serum androgen levels to within the physiologic range for young adults with primary and secondary adrenal insufficiency, possibly improve sexual function, improve mood and self-esteem, and decrease fatigue/exhaustion. Whereas DHEA replacement therapy may be effective in treating patients with adrenal insufficiency, human clinical trials investigating its efficacy in conditions such as systemic lupus erythematosus, HIV, Alzheimer disease, advancing age, male sexual dysfunction, perimenopausal symptoms, depression, and cardiovascular disease have not provided consistent findings.

Antigen-specific CD4 T cell clonal expansion and differentiation in the aged lymphoid microenvironment. I. The primary T cell response is unaffected

Aging is associated with changes in the immune system that lead to decreased immunity in the elderly. Prior studies from humans and mice have shown that aged T cells exhibit numerous defects, including decreased proliferation following in vitro stimulation, suggesting that intrinsic defects exist within aged T cells, leading to defective T cell activation and clonal expansion. In vivo, however, cellular and soluble factors in the lymphoid microenvironment influence T cell function. To investigate the effects of the aged lymphoid microenvironment on T cell function, we monitored the immune response of CD4 T cells from DO11.10 TCR transgenic mice following adoptive transfer into young and aged hosts. After immunization with specific antigen similar rates of donor DO11.10 T cell division were observed in the two host types. However, at the peak of the response, greater numbers of DO11.10 T cells were found in the aged hosts. Regardless of the age of the host, the donor DO11.10 T cell population differentiated into functional effector cells. Despite the increased CD4 T cell growth in aged hosts, similar numbers of memory DO11.10 T cells were found in young and in aged hosts. As CD4 T cell clonal expansion and differentiation is not impaired in the aged microenvironment, our data suggest that diminished T cell immunity during aging is largely due to intrinsic T cell defects, rather than to extrinsic influences associated with the aged lymphoid microenvironment.

Origin of germ cells and formation of new primary follicles in adult human ovaries

Recent reports indicate that functional mouse oocytes and sperm can be derived in vitro from somatic cell lines. We hypothesize that in adult human ovaries, mesenchymal cells in the tunica albuginea (TA) are bipotent progenitors with a commitment for both primitive granulosa and germ cells. We investigated ovaries of twelve adult women (mean age 32.8 +/- 4.1 SD, range 27-38 years) by single, double, and triple color immunohistochemistry. We show that cytokeratin (CK)+ mesenchymal cells in ovarian TA differentiate into surface epithelium (SE) cells by a mesenchymal-epithelial transition. Segments of SE directly associated with ovarian cortex are overgrown by TA, forming solid epithelial cords, which fragment into small (20 micron) epithelial nests descending into the lower ovarian cortex, before assembling with zona pellucida (ZP)+ oocytes. Germ cells can originate from SE cells which cover the TA. Small (10 micron) germ-like cells showing PS1 meiotically expressed oocyte carbohydrate protein are derived from SE cells via asymmetric division. They show nuclear MAPK immunoexpression, subsequently divide symmetrically, and enter adjacent cortical vessels. During vascular transport, the putative germ cells increase to oocyte size, and are picked-up by epithelial nests associated with the vessels. During follicle formation, extensions of granulosa cells enter the oocyte cytoplasm, forming a single paranuclear CK+ Balbiani body supplying all the mitochondria of the oocyte. In the ovarian medulla, occasional vessels show an accumulation of ZP+ oocytes (25-30 microns) or their remnants, suggesting that some oocytes degenerate. In contrast to males, adult human female gonads do not preserve germline type stem cells. This study expands our previous observations on the formation of germ cells in adult human ovaries. Differentiation of primitive granulosa and germ cells from the bipotent mesenchymal cell precursors of TA in adult human ovaries represents a most sophisticated adaptive mechanism created during the evolution of female reproduction. Our data indicate that the pool of primary follicles in adult human ovaries does not represent a static but a dynamic population of differentiating and regressing structures. An essential mission of such follicular turnover might be elimination of spontaneous or environmentally induced genetic alterations of oocytes in resting primary follicles.

Estrogen replacement, aging, and cell-mediated immunity after injury

We recently demonstrated that aged mice are less likely to survive following traumatic injury and are more immunosuppressed than young mice who sustain comparable injuries. Immunosuppression in severely injured patients and in rodent models of burn injury is associated with a marked elevation in proinflammatory cytokines, including interleukin-6 (IL-6). We reported that after sustaining a moderate-size scald injury, aged mice have higher circulating levels of IL-6 than young, injured mice. As proestrus levels of estrogen have been reported to boost immune responses and attenuate IL-6 production, in the present study, we went on to determine if estrogen replacement in aged female mice restored cellular immunity and proinflammatory cytokine production. After injury, in placebo-treated, aged animals, there was a >75% suppression in the delayed-type hypersensitivity response relative to placebo-treated, sham-injured, aged mice (P<0.05). In contrast, estrogen supplementation before injury yielded a partial recovery in this response, such that the mice were suppressed by only 40% relative to sham-injured, aged mice (P<0.05). There was a fourfold increase in the circulating level of IL-6 in burn-injured, aged mice who received placebo hormone replacement relative to sham-injured mice given placebo (P<0.05). This level of cytokine was lowered by nearly 50% in aged, estrogen-treated mice. Most remarkably, estrogen replacement improved survival from 42% (in the absence of estrogen) to 70% in aged, burn-injured mice. Further investigation will be needed to determine if age- and gender-specific therapies are needed for the treatment of all trauma patients.

HIV infection and aging: enhanced Interferon- and Tumor Necrosis Factor-alpha production by the CD8+ CD28- T subset

BACKGROUND

T cells from HIV+ and aged individuals show parallels in terms of suppressed proliferative activity and interleukin-2 (I1-2) production and an increased number of CD8+ CD28- T cells. In order to compare cytokine production from T cells from these two states, CD4+ and CD8+ T cells from HIV+ aged, and normal young donors (controls) were monitored for cytokine production by flow cytometry, quantitative PCR and ELISA upon activation by PMA and anti-CD3. In addition, the CD8+ T cell subsets CD28+ and CD28- from the HIV+ and the aged groups were evaluated for cytokine production by flow cytometry, and compared with those from young controls.

RESULTS

Flow cytometric analysis indicated that CD8+ T cells from both HIV+ and aged donors showed an increase of approximately 2-3 fold over controls in percentage of cells producing inflammatory cytokines IFN-gamma and TNF-alpha. Similar analysis also revealed that the production of interleukins-4,6 and 10, production was very low (1-2% of cells) and unchanged in these cells. Quantitative PCR also showed a substantial increase (4-5 fold) in IFN-gamma and TNF-alpha mRNA from HIV+ and aged CD8+ T cells, as did ELISA for secreted IFN-gamma and TNF-alpha (2.3-4 fold). Flow cytometric analysis showed that the CD8+ CD28- T cell subset accounts for approximately 80-86% of the IFN-gamma and TNF-alpha production from the CD8+ subset in the aged and HIV+ states. The CD4+ T cell, while not significantly changed in the HIV+ or aged states in terms of IFN-gamma production, showed a small but significant increase in TNF-alpha production in both states.

CONCLUSIONS

Our data appear compatible with physiologic conditions existing in HIV+ and aged individuals, i.e. elevated serum levels and elevated CD8+ T cell production of IFN-gamma and TNF-alpha. Thus, the capacity for increased production of cytokines IFN-gamma and TNF-alpha in the aged individual by the dominant CD8+ CD28- subset may have a profound influence on the clinical state by aggravating inflammatory pathologies such as rheumatoid arthritis, and possibly Alzheimer's disease and Crohn's disease. In AIDS, these cytokines may contribute to wasting and cachexia. We theorize that the predominant phenotypic change to the cytotoxic CD8+ CD28- T cell subsets in both the HIV+ and the aged states may reflect a natural "endpoint" in CD8+ T cell differentiation induced after a lifetime of immune activity (toward viruses, etc) in the aged, and after a massive accelerated response to HIV in the HIV-positive individual.

Age-dependent decrease in Toll-like receptor 4-mediated proinflammatory cytokine production and mitogen-activated protein kinase expression

Age-related changes in immunity render elderly individuals more susceptible to infections than the young. Previous work by our laboratory and others showed that macrophages from aged mice are functionally impaired. Macrophages produce proinflammatory cytokines, tumor necrosis factor alpha (TNF-alpha) and interleukin (IL)-6, when stimulated with lipopolysaccharide (LPS), which signals through Toll-like receptor-4 (TLR4) and requires activation of mitogen-activated protein kinases (MAPKs). We investigated whether aging is associated with alterations in TNF-alpha and IL-6 production and MAPK expression and activation in thioglycollate-elicited peritoneal macrophages from mice. Kinetics and LPS dose-responsiveness of macrophage TNF-alpha production did not differ by age. Unstimulated macrophages did not differ by age in their cytokine production. However, LPS-stimulated (100 ng/mL) cultures from aged mice produced 100 +/- 30 pg/mL TNF-alpha and 6000 +/- 2000 pg/mL IL-6, and those from young mice produced 280 +/- 50 pg/mL and 10,650 +/- 10 pg/mL, respectively (P<0.05). Likewise, levels of activated MAPKs did not differ by age in unstimulated macrophages, and LPS-stimulated macrophages from aged mice had <70% activated p38 and c-jun NH(2)-terminal kinase (JNK) than those of young controls. Of particular interest, we observed >25% reduction of total p38 and JNK in macrophages from aged mice relative to young. In addition, surface TLR4 levels did not vary with age. We conclude that macrophages from aged mice exhibited suppressed proinflammatory cytokine production, which correlated with diminished total levels and LPS-stimulated activation of p38 and JNK. These observations suggest that decreased MAPK expression could be a mechanism responsible for age-related deterioration of the immune system.

Aging Is Associated With Increased T-Cell Chemokine Expression in C57Bl/6 Mice

To better understand the contribution of the chemokine system in immune senescence, we determined the aging effect on CD4+ and CD8+ T-cell chemokine expression by microarray screening and ribonuclease protection assays. Compared with young C57BL/6 mice, freshly isolated CD4+ cells from aged mice express increased level of interferon-gamma-inducible protein 10 (IP-10), macrophage inflammatory protein (MIP)-1alpha, MIP-1beta, regulated upon activation, normal T-cell expressed and secreted (RANTES), and lymphotactin (Ltn). T-cell receptor (TCR)/coreceptor stimulation up-regulates MIP-1alpha, MIP-1beta, and Ltn, and down-regulates IP-10 and RANTES expression in CD4+ T cells. A similar increase in chemokine expression was demonstrated in the CD8+ T cell. Enzyme-linked immunosorbent assays confirmed increased T-cell chemokine protein production in old CD4+ and CD8+ T cells. Finally, supernatant of cultured T cells from old animals caused an enhanced leukocyte chemotaxis response compared with that from young animals, suggesting that the age-related difference in T-cell chemokine expression has an important functional consequence.

Statin therapy in the elderly: does it make good clinical and economic sense?

HMG-CoA reductase inhibitors (statins) have been established as the dominant treatment for coronary heart disease (CHD). This dominance is based on an impressive body of clinical trial evidence showing significant benefits in primary prevention of cardiovascular events in individuals at risk for CHD and in secondary prevention of such events in patients with CHD and high or normal plasma cholesterol levels. There is, however, significant room for improvement in the treatment of CHD with respect both to drug efficacy and to the disparity between evidence-based medicine and actual clinical practice particularly in relation to treatment strategies for the elderly. Current statins fall short of requirements for 'ideal' lipid-lowering treatment in several respects; 'super' statins and other agents currently in development may satisfy more of these requirements. Moreover, available therapies are not applied optimally, because of physician nonacceptance and/or patient noncompliance; thus, the majority of patients with CHD or its risk factors still have cholesterol levels that exceed guideline targets. There is also evidence that older patients with CHD, or at high risk of CHD, are undertreated - possibly because of concerns regarding the increased likelihood of adverse events or drug interactions or doubts regarding the cost effectiveness of statin therapy in this population. This group is of particular clinical relevance, since it is showing a proportionate rapid expansion in most national populations. To address their potential healthcare needs, the ongoing Pravastatin in the Elderly at Risk (PROSPER) study is assessing the effects of pravastatin in elderly patients (5804 men and women aged 70-82 years) who either have pre-existing vascular disease or are at significant risk for developing it, with the central hypothesis that statin therapy (pravastatin 40 mg/day) will diminish the risk of subsequent major vascular events compared with placebo. After a 3.2-year treatment period, a primary assessment will be made of the influence of statin treatment on major cardiovascular events (a combination of CHD death, nonfatal myocardial infarction, and fatal or nonfatal stroke). Optimal deployment of the currently available agents and of newer agents (no matter how well they satisfy requirements for ideal treatment) ultimately depends on the establishment of an evidence base and may require far-reaching educational programmes that change the way risk factor management is viewed by caregivers and patients alike.

Phenotypic effects of somatic cell cloning in the mouse

Although a variety of phenotypes and epigenetic alterations have been reported in animals cloned from somatic cells, the exact nature and consequences of cloning remain unclear. We cloned mice using fresh or short-term cultures of donor cells (cumulus cells, immature Sertoli cells, and fetal or adult fibroblast cells) with defined genetic backgrounds, and then compared the phenotypic and epigenetic characteristics of the cloned mice with those of fertilization-derived control mice. Irrespective of the nucleus-donor cell type, about 50% of the reconstructed embryos developed to the morula/blastocyst stage, but about 90% of these clones showed arrested development between days 5 and 8, shortly after implantation. Most of the clones were alive at term, readily recovered respiration, and did not show any malformations or overgrowths. However, their placentas were two- to threefold larger than those of the controls, due to hyperplasia of the basal (or spongiotrophoblast) layer. Although there was significant suppression of a subset of both imprinted and non-imprinted placental genes, fetal gene suppression was minimal. The seven imprinted genes that we examined were all expressed correctly from the parental alleles. These findings were consistent for every cell type from the midgestation through term stages. Therefore, cloning by nuclear transfer does not perturb the parent-specific imprinting memory that is established during gametogenesis, and the phenotypic and epigenetic effects of cloning are restricted to placental development at the midgestation and term stages. Twelve male mice that were born in a normal manner following nuclear transfer with immature Sertoli cells (B6D2F1 genetic background) were subjected to long-term observation. They died earlier than the genotype-matched controls (50% survival point: 550 days vs. 1028 days, respectively), most probably due to severe pneumonia, which indicates that unexpected phenotypes can appear as a result of the long-term effects of somatic cell cloning.

Aging enhances lymphocyte cytokine defects after injury

Mortality and sepsis after a traumatic injury is greater in the elderly than in young individuals. The altered lymphocyte response observed to occur in healthy aged individuals is proposed to be a contributing factor to increased mortality. The immune response associated with the increased mortality was explored using a murine scald injury model. In the absence of injury, aged mice had depressed delayed-type hypersensitivity (DTH) and splenocyte proliferative responses relative to young mice. There was also an increase with age in the production of the TH2 cytokines interleukin (IL)-4 and IL-10 by splenocytes. There was no change in the TH1 cytokines IFNgamma or IL-12 with age. However, IL-2 production was significantly lower. Following injury, there was a further decrease in the DTH response of aged injured mice, compared with aged sham mice. In addition, there was a decrease in all of the cytokines examined, regardless of age. In contrast, IFNgamma and IL-2 were significantly lower in the aged injured animals compared with the young injured animals. These results suggest that the lack of an adequate amount of TH1 cytokines shortly after injury in the aged mice may parallel the increased incidence of sepsis and death that occurs in aged burn patients.

Enhanced differentiation of splenic plasma cells but diminished long-lived high-affinity bone marrow plasma cells in aged mice

In the present work, we have dissected the mechanisms responsible for the impaired humoral responses in aging. We found that there was a substantially higher level of Ab-forming cells in the spleens of aged mice than that of young controls. However, the number of high-affinity, class-switched Ab-forming cells was severely decreased in the spleen of aged mice. The accumulation of low-affinity IgM Ab-forming cells in the spleens of aged animals was not due to a deficiency in isotype switching because the number of total IgG1 splenic plasma cells was not significantly reduced. Remarkably, plasma cells of both low and high affinity were significantly diminished in the bone marrow of aged mice compared with that of young mice. The results from reconstitution experiments showed that aged bone marrow was less supportive for plasma cells derived from young splenic B cells. These findings suggest that humoral immune deficiency in aging results from at least two mechanisms: the inability to generate sufficient numbers of high-affinity Ab-forming cells, which is a result of diminished germinal center reaction, and the defective bone marrow environment that has diminished ability to support the selection and survival of long-term Ab-forming cells.

The effect of aging on immune responses

Although vaccine manufacturers make no specific recommendations regarding the vaccination of older horses and ponies, the similarities in age-induced immunologic changes between human beings and equids suggests that similar vaccination recommendations should be followed. The need for vaccination of the older horse depends, of course, on the relative risk of exposure for the individual horse. Particular care should be taken when using attenuated vaccine products because these live agents may pose a unique risk to the older individual. Immunization with inactivated agent vaccines is likely to be safer. In general, annual vaccination against equine influenza virus infection, tetanus, rabies, and encephalomyelitis viruses is warranted.

Inhibition of H2O2-induced apoptosis of lymphocytes by calorie restriction during aging

Calorie restriction (CR) is known to delay the aging process in rodents and is postulated to act by decreasing free radical generation and increasing antioxidant enzyme activity. The present study was designed to investigate the effect of CR and age on oxidative stress-induced apoptosis and associated changes in the levels of TNF-alpha, and Bcl-2 in splenic T lymphocytes. Ad libitum (AL)- or CR-fed C57BL/6J mice were sacrificed either at 6 (young) or 18 (old) months and splenic lymphocytes were incubated with or without 25 micro M H2O2 to induce apoptosis. Apoptosis increased with age in cells of AL-fed mice incubated with H2O2. CR prevented this rise in apoptosis in total splenic lymphocytes and in CD4(+) and CD8(+) T lymphocyte subsets either with or without H2O2. Free radicals increased and mitochondrial membrane potential decreased in aged mice. CR prevented these changes and also prevented the age-associated increase in TNF-alpha and loss of Bcl-2 in total splenic lymphocytes and in CD4(+) and CD8(+) lymphocyte subsets. In summary, lymphocytes in aged AL-fed mice were much more susceptible to oxidative stress-induced apoptosis whereas CR normalized apoptosis by preventing the increase in TNF-alpha and the decrease in Bcl-2 associated with aging.

The frail elderly: role of dendritic cells in the susceptibility of infection

The decline in immunity in the elderly has largely been attributed to impairment of T cell mechanisms. This seems reasonable since the thymus involutes with age, so that the number of naïve cells to respond to new foreign antigens also declines. However, little is known about how aging affects antigen-presenting cells (APC) that are responsible for the initiation and outcome of effector T cell immune responses. This review focuses on the age-related alterations of a key APC, the dendritic cell (DC). Recent findings suggest that interleukin-10, a key cytokine that can suppress cell mediated immunity and maturation of DC subsets, is elevated in the very healthy elderly. However, production of IL-12, required for the initiation of T cell immune responses, declines in frail elderly along with DC antigen presenting function. These findings suggest that shifts in IL-10 and IL-12 may not only directly influence immune response but may also alter the balance and maturation of DC subsets. Finally, study of immunologic differences between the very healthy and frail elderly may reveal important changes in DC function and regulation influenced by age and/or environment (disease, nutrition, medications, etc.).

Influence of ageing on Langerhans cell migration in mice: identification of a putative deficiency of epidermal interleukin-1beta

Previous studies in mice have reported a decrease in epidermal Langerhans cell (LC) density in aged skin, however, the impact of this reduction on LC function and cutaneous immune responses is unclear. In the present series of experiments, the frequency of major histocompatibility complex class II+ LC in the epidermis of older (6-month-old) mice was found to be reduced significantly compared with that observed for young (6-8-week-old) mice. LC mobilization and the subsequent accumulation of dendritic cells (DC) in regional lymph nodes in response to topical challenge with a chemical allergen were found to be less vigorous in older mice. Flow cytometric analyses of DC derived from the draining lymph nodes of fluorescein isothiocyanate (FITC)-sensitized mice revealed that the frequency of FITC+-DC arriving in draining lymph nodes was also reduced in older mice but that the fluorescence intensity was comparable. Control and allergen-treated-older mice also displayed decreased total lymph node cellularity. Contact hypersensitivity responses were found not to be compromised in older mice. However, the cytokine regulation of LC migration in the two age groups of mice did differ. LC migration provoked by intradermal injection of tumour necrosis factor-alpha (TNF-alpha) was reduced in older animals, whereas, the percentage of LC that migrated in response to exogenous interleukin-1beta (IL-1beta) was comparable for both young and aged mice. Since both allergen- and TNF-alpha-induced LC responses are known to require receipt by LC of a signal from IL-1beta for effective migration, the suggestion is that impaired LC migration in older mice may be due to a reduced availability of epidermal IL-1beta.

Early death of mice cloned from somatic cells

Here we report that the lifespan of mice cloned from somatic cells is significantly shorter than that of genotype- and sex-matched controls, most likely due to severe pneumonia and hepatic failure. This finding demonstrates the possibility of long-term deleterious effects of somatic-cell cloning, even after normal birth.

The inflammation hypothesis of aging: molecular modulation by calorie restriction

Current evidence strongly indicates that reactive oxygen species (ROS) and reactive nitrogen species (RNS) are widely implicated in the inflammatory process. However, mechanistic information is not readily available on the extent to which ROS/RNS contributes to the proinflammatory states of the aging process. The involvement of the underlying inflammation during the aging process and the molecular delineation of anti-inflammatory action of calorie restriction (CR) is described. Age-related upregulations of NF-kappaB, IL-beta, IL-6, TNFalpha, cyclooxygenase-2, and inducible NO synthase are all attenuated by CR. The suppression of the NF-kappaB activation was accomplished by blocking the dissociation of inhibitory IkappaBalpha and IkappaBbeta by CR. These findings provide underlying molecular insights into the anti-inflammatory action of CR in relation to the aging process. Based on these and other available data, it is suggested that the "Inflammation Hypothesis of Aging" supports the molecular basis of the inflammatory process as a plausible cause of the aging process.

RANTES and MIP-1alpha production by T lymphocytes, monocytes and NK cells from nonagenarian subjects

While numerous previous studies have investigated age-related changes of cytokine production, little is known about chemokines, the importance of which in regulating immune response is becoming increasingly evident. In this study, a group of healthy subjects over 90 years old is compared to a group of young subjects, we evaluated the ability of monocytes, T lymphocytes and NK cells: (1) to produce RANTES and MIP-1alpha, either in basal conditions or after stimulation with, respectively, LPS, anti-CD3 MoAb and IL-2; (2) to express the corresponding chemokine receptors (CCR1, CCR3, CCR5). We demonstrate that: (a) monocytes, T lymphocytes and NK cells spontaneously produced detectable amounts of chemokines, both in young and old subjects; (b) monocyte-dependent RANTES and MIP-1alpha production induced by LPS was up-regulated in nonagenarian subjects as anti-CD3-induced secretion from T cells; (c) RANTES and MIP-1alpha production by IL-2 stimulated NK cells was reduced in elderly subjects; (d) CCR1, CCR3 and CCR5 were widely expressed on monocytes, but less expressed on T lymphocytes and NK cells. The diversity within PBMC might reflect their different states of activation and/or responsiveness, influencing the ability to develop rapid innate and long-lasting adaptive immune responses.

Modulation of human lymphocyte proliferative response with aging

Previously, we have demonstrated age-associated alterations in transmembrane signaling. One of the most reproducible alterations found in the immune response with aging is the decrease of lymphocyte proliferation on stimulation with various different mitogens. Here, we confirm that proliferative responses to stimulation with phytohaemagglutin (PHA), recombinant human IL-2, or anti-CD3 monoclonal antibody are all greater in the young (20-25 years) than old (60-87 years) population. We attempted to modulate the proliferative response using various agents acting at different levels of transmembrane signaling (pertussis toxin, cholera toxin, isoproterenol, PMA, Ca ionophore A23187), as well as at the level of the lymphocyte plasma membrane (methyl-beta-cyclodextrin, MBCD), or by using antioxidant vitamins (Vitamin E or C). None of these agents was able to restore effectively the proliferative response of lymphocytes from the aged to the level of young subjects. Even the combination of A23187 and PMA acting directly on calcium metabolism and protein kinase C activity was insufficient to restore the decreased mitogenic capacity of T cells from elderly subjects. Cyclodextrin, which decreases the cholesterol content of the membrane, increased the proliferative response of lymphocytes of elderly subjects, but not to the level of the young. Vitamin E had a very strong inhibitory effect on lymphocyte stimulation in both the age groups, except in combination with MBCD in T cells of the elderly, while Vitamin C had no significant modulatory effect. MAPK ERK and p38 activation was found to be decreased with aging in T cells after anti-CD3 mAb stimulation. Vitamin E but not Vitamin C strongly inhibited MAPK ERK or p38 activation. The direct activation of certain molecules or the modulation of the cholesterol content of the membrane seems to be effective immunomodulatory interventions with aging.

Vitamin C, vitamin E, and beta-carotene in relation to common cold incidence in male smokers

We evaluated the role of dietary vitamin C, vitamin E, and beta-carotene, as well as long-term vitamin E and beta-carotene supplementation, on the incidence of common cold episodes. A cohort of 21,796 male smokers was drawn from the Alpha-Tocopherol Beta-Carotene Cancer Prevention Study, which examined the effects of 50 mg per day vitamin E and 20 mg per day beta-carotene on lung cancer. Diet and background characteristics were recorded at the study entry, and subjects were queried three times per year on common cold episodes. We modeled the total number of colds during a 4-year follow-up period with Poisson regression, adjusting for covariates of dietary intake. Dietary vitamins C and E and beta-carotene had no meaningful association with common cold incidence. Long-term vitamin E and beta-carotene supplementation had no overall effect.Among subjects 65 years of age or older, the incidence of colds was slightly lower in the vitamin E group (RR = 0.95; 95% CI = 0.90-1.00); this reduction was greatest among older city dwellers who smoked fewer than 15 cigarettes per day (RR = 0.72; 95% CI = 0.62-0.83). In this male smoking population, vitamins C and E and beta-carotene had no overall association with the incidence of common cold episodes.

Issues surrounding age: vascular disease in the elderly

One-fifth of all humans who have survived beyond the age of 65 are alive today, and in the industrialized world the elderly segment of the population is expanding most rapidly. In biological terms, these survivors are healthier than the elderly of previous generations. However 'there are no diseases peculiar to old age and very few from which it is exempt' (Alfred Worcester, 1855-1951), and so society will inevitably accumulate a significant share of degenerative diseases within the ranks of its senior citizens. In the last two decades, the prevalence of stroke, diabetes mellitus, arthritis and heart disease has increased significantly as a tangible index of ageing in the population, and these diseases have been accompanied by degenerating cognitive function and physical disability, both of which are adding increasing stress to community healthcare and social services. Policy-makers need to understand and monitor these trends in order to make informed and cogent decisions about the management of this growing problem. This review highlights some of the key health issues facing the elderly in regard to coronary artery disease, insulin resistance, redox status, and statin therapy, in the hope that enlightened debate will inform decision making on resource allocation for this important and growing segment of society.

The influence of aging and sex hormones on expression of growth hormone-releasing hormone in the human immune system

GHRH is a neuropeptide that has also been localized to the immune system. The physiological function of GHRH in the immune system has not been elucidated. This study was conducted to determine whether immune GHRH expression is altered in certain pathological states, such as immune cell tumors, and whether gender, aging, and alterations in the sex steroid milieu influence the expression of this peptide in immune cells. Using double color flow cytometry, GHRH protein was found to be expressed in less than 2% of peripheral blood mononuclear cells (PBMC). Monocytes and B and T cells all expressed GHRH protein, although a greater percentage of T cells compared with B cells and monocytes expressed GHRH (5- to 7-fold). Semiquantitative RT-PCR was used to quantify GHRH messenger ribonucleic acid (mRNA) in PBMC and several immune cell-derived tumors. PBMC and granulocytes expressed low levels of GHRH mRNA with relatively higher levels of expression in monocytes. The tumor cell lines CEMX 174 (B/T cells), HUT 78 (T cells), WIL2-N (B cells), U937 (monocytes/macrophages), and JM 1 (pre-B cell lymphoma) all showed greater expression of GHRH mRNA relative to PBMC. However, two cell lines, CCRF-SB, a B lymphoblastoid cell line, and HL-60, a promyelocytic cell line, expressed GHRH mRNA at similar levels as PBMC. A significant decrease in the percentage of lymphocytes (CD45(+) cells) expressing GHRH protein was found in age-advanced men and women compared with young men and women. This decline was noted in B cells (CD20(+)) and monocytes (CD14(+)), but not in T cells (CD3(+)). GHRH mRNA expression in PBMC derived from postmenopausal women was lower than that from premenopausal women. However, no differences in PBMC GHRH mRNA expression were found in young and old men. Although in older men there were fewer peripheral lymphocytes that express GHRH protein, these cells secreted significantly more GHRH in vitro than cells from postmenopausal women with no hormone replacement therapy (HRT), but similar levels as cells from women receiving HRT. PBMC from women receiving HRT secreted more GHRH in vitro than cells from women receiving no hormone replacement. This study demonstrates that the expression of immune GHRH is dynamic, and therefore likely to be regulated. Increased expression of GHRH in certain immune tumors suggests that GHRH may be mitogenic under certain conditions and therefore play a role in the pathogenesis of select immune cell tumors. Collectively, these results suggest a role for GHRH as a local immune modulator and in the pathophysiology of immunosenescence and immune cell tumors.

Ultrastructural study of the FVB/N mouse thymus: presence of an immature epithelial cell in the medulla and premature involution

FVB/N inbred mice have been widely used to generate a variety of transgenic lines, but their physiology and especially their immunological characteristics are poorly documented. We therefore studied the ultrastructure of the thymus and the distribution of thymocyte subpopulations in FVB/N mice at several ages. In young FVB/N mice the stromal microenvironment exhibits the three types of epithelial cells and the two types of bone-marrow derived cells (macrophages and interdigitated cells) previously described in other strains of mice. Moreover, in the thymic medulla of young FVB/N mice, a fourth cell type with the morphological characteristics of an immature epithelial cell was present in relatively high number. Furthermore, thymocyte subpopulations distribution shows an earlier thymocyte maturation than in other strains. Finally, changes associated with thymic involution were observed about 5 months earlier than in many other mouse strains. Our results demonstrated that the FVB/N strain has a specific immunological status.

Immunosenescence: a review

Aging involves the morphological and functional integrity of all organs, including the cellular and humoral immunological functions. The main alterations can be listed as follows: (i) Thymic involution resulting in the decreased number of lymphoid precursor T- and B-cells. (ii) Reduced proliferative capacity of T-cells; loss of lymphocyte subgroups as a consequence of the shortening of telomeres. (iii) Qualitative deficiency of B-lymphocytes with a reduced response to exogenous antigens. (iv) Compromised activity of the accessory cells, both directly by depressing the chemotactic and phagocytic responses, and indirectly by increasing the prostaglandin production which inhibit the proliferation of T-cells. (v) Alterations in the production and secretion of various cytokines. (vi) Other factors like the general physiological conditions, the nutritional state, psychological habit and various hormone levels.

Effect of synthetic thymic and pineal peptides on biomarkers of ageing, survival and spontaneous tumour incidence in female CBA mice

Fifty female CBA mice were injected s.c. either with 0.1 ml saline, or with synthetic thymic dipeptide Lys-Glu or with synthetic pineal tetrapeptide Ala-Glu-Asp-Gly both in a single dose of 0.1 microg/animal monthly for five consecutive days from the age of 6 months until natural death. Lys-Glu did not significantly influence the body weight and food consumption, free radical processes and estrus function in mice and did increase their physical activity with the subsequent decrease in spontaneous lung adenomas incidence. The pineal peptide treatment was failed to modify the food consumption and physical strength of mice, and was followed by the increase in the body weight, mean survival (by 5.3%, P<0.05) and maximum (by 10 months), by slow down of the ageing of estrus function, by the decrease in body temperature, physical activity, free radical processes and spontaneous tumor incidence (mainly, lung adenomas) in mice. These data suggest the geroprotector potential of the pineal peptide.

Chemokine production by peripheral blood mononuclear cells in elderly subjects

The function of chemokines in promoting and modulating leukocyte migration is essential for a prompt and efficacious inflammatory response and in host defence against infections. In order to investigate whether this important aspect of immunological response is influenced by ageing, we evaluated the basal levels as well as the ability of peripheral blood mononuclear cells from young and healthy elderly subjects to produce chemokines (IL-8, MCP-1, MIP-Ialpha, RANTES) in response to stimulation with anti-CD3 monoclonal antibody and lipopolysaccharide (LPS), a gram negative bacterial endotoxin. Our main findings are a spontaneous chemokine production; a 20% decrease of proliferative response to anti-CD3 monoclonal antibody accompanied by an age related increase of MIP-Ialpha and RANTES production and by a general increase of all chemokine production compared to unstimulated conditions; a proliferative defect of monocytes to LPS challenge associated with an increase of chemokine production compared to basal conditions with a progressive age-related increase of MIP-lalpha. In conclusion, this study suggests that chemokines could have a compensatory role in balancing the impaired mechanisms involved in 'specific' immune response during ageing. The successful activation of this strategy could contribute to the good performance of immune system so maintaining healthy status in elderly.

Aging, immunity, and cancer

BACKGROUND

The prime function of the immune system is to protect the entire organism from a variety of insults and illnesses, including the development of cancer. The question of how age-related declines in immune function contribute to an increasing incidence of malignancies continues to be a focus of discussion and speculation.

METHODS

The recent literature from the National Library of Medicine database (1990 through the present) was searched for articles using the medical subject headings (MeSH terms) of aging, immunity, cancer, senescence, and apoptosis. Bibliographies of articles retrieved were also scanned.

RESULTS

Data from in vitro and in vivo animal and human studies demonstrate clear age-related alterations in both the cellular and humoral components of the immune system, but there is little evidence supporting direct causal links between immune senescence and most malignancies.

CONCLUSIONS

Senescent decline in immune surveillance leads to the accumulation of cellular and DNA mutations that could be a significant factor in the development of malignancy and programmed cell death or apoptosis observed in the elderly.

Androstenediol-induced restoration of responsiveness to influenza vaccination in mice

Androstenediol (AED), a metabolite of dehydroepiandrosterone (DHEA) regulates innate and adaptive immune responses. To examine whether AED could effectively reverse the age-associated decline of antiviral immunity, 3-, 10-, and 22-month-old mice were treated with AED-sulfate (AED-S) for 45 days beginning 10 days prior to vaccination. Subsequently, mice were primed and boosted with suboptimal doses of a commercially-available trivalent influenza vaccine. Treatment of 10-month-old animals with AED-S during vaccination increased the titer of circulating antiviral immunoglobulin G to levels comparable with those in 3-month-old mice. Furthermore, AED-S treatment protected 10-month-old animals from intranasal challenge with a lethal dose of influenza virus 21 days after secondary vaccination. Although AED-S treatment of 22-month-old mice did not enhance vaccine responses and failed to protect against lethal challenge, the data from the 10-month-old animals suggest that treatment with AED-S will prevent the early manifestations of immunosenescence.

The effect of a ceramide analog, N-acetylsphingosine on the induction of proliferation and IL-2 synthesis in T cells from young and old F344 rats

Ceramide is a physiological mediator of extracellular signals that control various cellular functions, including proliferation and apoptosis. In the present study, we examined the effects of cell-permeable ceramide analog, N-acetyl-sphingosine (C(2)-ceramide) on the induction of proliferation and interleukin-2 (IL-2) synthesis in T cells from young and old rats. Splenic T cells from 6- and 24-month-old Fischer 344 rats were treated with C(2)-ceramide and then incubated with anti-CD3 antibody for 24 or 48 h. The induction of proliferation and IL-2 production by anti-CD3 was significantly (P<0.001) lower in T cells from old rats compared to T cells from young rats. C(2)-ceramide treatment resulted in suppression of proliferation and IL-2 production in a concentration-dependent manner. The suppressive effect of C(2)-ceramide on proliferation and IL-2 production was greater in T cells from old rats than T cells from young rats. We investigated whether this decreased responsiveness was due to induction of program cell death (apoptosis) and found that there was a significant increase in DNA fragmentation in C(2)-ceramide treated and anti-CD3 stimulated T cells from both young and old rats. The increase in DNA fragmentation was paralleled with an increase in caspase-3 activation. C(2)-ceramide-induced caspase-3 activation and DNA fragmentation was significantly (P<0.5) higher in stimulated T cells from old rats compared to stimulated T cells from young rats. These results suggest that the sphingomyelin-ceramide signaling pathway may play an important regulatory role in the well-documented age-related decline in immune function.

Changes in immune function with age

Aging is associated with a decline in immune function in humans and animals. The primary defects appear to reside in the T-cell compartment. Improving understanding of the mechanisms underlying the general decline in immune functions with age may enhance our ability to prevent and treat age-associated illnesses. Development of biomarker(s) of immune senescence may eventually help clinicians to identify subpopulations of the elderly who are at risk for infections, malignancies, and possibly autoimmune diseases.

Effect of vilon on biological age and lifespan in mice

Subcutaneous administration of vilon (Lys-Glu) to female CBA mice starting from the 6th month of life increased physical activity and endurance, decreased body temperature, prolonged the lifespan, and prevented the development of spontaneous neoplasms. Vilon had no effect on age-related changes of estrous function and free radical processes. Long-term administration of vilon caused no unfavourable effects on animal development. The obtained results show safety of chronic vilon administration and allow to use this preparation for geroprotection and prophylaxis of age pathology.

Dietary vitamin E and T cell-mediated function in the elderly: effectiveness and mechanism of action

One of the most dramatic and consequence-bearing age-related phenomena is the decline of the immune function with old age. Age-related T cell-mediated immunity dysfunction has been implicated in the etiology of many of the chronic degenerative diseases of the elderly, including arthritis, cancer, autoimmune diseases and increased susceptibility to infectious diseases. T cells from aged individuals are impaired in their response to mitogens and in their cytokine production. In recent years, several studies have emphasized the importance of intracellular anti-oxidant levels for preserving the immune function. Recent progress in understanding the mechanisms of action of anti-oxidants on cellular metabolism, have shown that anti-oxidants may modulate signal transduction and gene expression in immune cells. Vitamin E is widely recognized as a major lipid-soluble chain-breaking anti-oxidant in the biological membrane, where it scavenges free radicals, inhibiting the initiation and chain propagation of lipid peroxidation and protecting cellular structures against oxidative stress damage. Experimental studies have provided evidences for a role of vitamin E in protecting the immune system of elderly subjects. This article reviews the studies concerning the effect of both vitamin E deficiency and supplementation on T cell-mediated immune function in aging. Following a chronological pathway, the present article will also discuss the knowledge regarding the underlying mechanism of action of vitamin E.

Dietary (n-6) and (n-3) fatty acids and energy restriction modulate mesenteric lymph node lymphocyte function in autoimmune-prone (NZB x NZW)F1 mice

We previously showed that dietary fish oil (FO) and energy restriction (R) have beneficial anti-inflammatory properties in the peripheral blood and spleens of (NZB x NZW)F1 (B/W) lupus-prone mice. Furthermore, unsaturated fatty acids also were shown in the past to influence mesenteric lymph node (MLN) lymphocyte function in healthy young rats. The MLN play a pivotal role in mediating food allergy. To date, the effect of R on intestinal immunity is not well understood; therefore we determined the effect of diet on MLN lymphocyte function. Mice were given either free access to a 5 g/100 g corn oil (CO) or fish oil (FO) diet or the same corn oil (CR) or fish oil (FR) diets restricted to 60% of the intake of the control group. At the age of 4 (young) and 8 (old) mo, MLN lymphocytes were isolated and B- (CD19(+)) and T-lymphocyte subsets (CD4(+) and CD8(+)) were determined by flow cytometry. Additional MLN lymphocytes were placed in culture with or without concanavalin A and culture supernatants collected after 72 h for cytokine and immunoglobulin (Ig) quantitation by ELISA. Aging significantly (P < 0.05) decreased both CD4(+) and CD8(+) T-lymphocytes. Spontaneous and activation-induced interleukin-4 (IL-4), IL-10, and interferon-gamma secretion were greater while IL-2 was lower in CO-fed old mice compared to CO-fed young mice. In contrast, CR or FO alone partially blunted the age-dependent alterations in T-lymphocyte ratios including cytokine and Ig secretion, whereas the FR diet significantly (P < 0.005) normalized the accelerated aging effects on these immune variables. We show for the first time that FR is a far more potent anti-inflammatory therapy than either CR or FO alone in modulating MLN lymphocyte function.

Alterations in splenic architecture and the localization of anti-double-stranded DNA B cells in aged mice

Aging is characterized by a decline in humoral immunity and a concommitant increased incidence of anti-DNA and other autoantibodies. To define how the regulation of autoreactive B cells is altered with age, we have used BALB/c mice with an Ig heavy H chain transgene to track the fate of anti-double-stranded (ds) DNA B cells in vivo. In young adult mice, anti-dsDNA B cells are developmentally arrested and excluded from the splenic B cell follicle, whereas in most aged mice they are mature and localize within the B cell follicle. Furthermore, we have detailed global changes in lymphoid architecture that accompany aging: CD4(+) T cells are found not only in the periarteriolar lymphoid sheath, but also in the B cell follicles. Strikingly, these disruptions are similar to those that precede serum anti-dsDNA antibody expression in autoimmune MRL-lpr/lpr mice.

Distinct categories of immunologic changes in frail elderly

Immune changes and their relationships in a frail elderly population (N=116, age 70-103, median 86 years) were defined in comparison to a healthy younger group. Previous immune studies in the elderly have generally focused on one or few parameters without correlation analyses. Furthermore, the study populations have been active elderly in relatively small numbers. A total of 33 immune parameters representing many aspects of the immune system were quantified. Most changes in the frail elderly were parallel to those reported in active elderly. A classification tree analysis revealed that increased plasma activation markers (neopterin and sTNF-R) and increased CD28 expression on CD8 T cells and proliferative response separated the aged and control populations. Statistical procedures utilizing principal components analyses, partial correlations and exploratory factor analyses all indicated that immunologic parameters in frail elderly are grouped in three major clusters of immunologic results. These involved (a) increased plasma levels of neopterin and sTNF receptor indicating elevated IFNgamma and TNF cytokine activity; (b) increased proportion of mature (CD45RO) versus naïve (CD45RA) T cells; and (c) a diverse group of related changes including impaired proliferative response, reduced T cells, CD28 and CD25 expression, B cell percentage and lower CD4:CD8 ratios and increased HLA-DR expression. These findings emphasize that several different groups of immune parameters but not 33 independent immune changes, occurred in the aged population.

Biogerontological research in Canada

There is an ever increasing interest in the study of the aging process. This review is aimed to make an overview of the biological aging research in Canada. I will summarize, to the best of my knowledge, the biological aging research undertaken actually in Canadian institutions dealing with various aspects of this research using many different experimental approaches, models from animals to humans and a huge array of techniques. The biological aging research is developing continuously in Canada, however, it is very important that we assist in a near future to its huge explosion if we would respond to the needs of an ever increasing aging population. Initiatives recently proposed by the Canadian government concerning the creation of Canadian Institutes on Health Research will provide good opportunities to establish a performant, cost-effective, and innovative biological aging research.

Age-related decline in activation of calcium/calmodulin-dependent phosphatase calcineurin and kinase CaMK-IV in rat T cells

We have previously shown that the DNA binding activity of the transcription factor NFAT which plays a predominant role in IL-2 transcription decreases with age. Because the transactivation (dephosphorylation and nuclear translocation) of the NFAT-c (cytoplasmic component of the NFAT complex) is mediated by the calcium/calmodulin-dependent phosphatase, calcineurin (CaN), and because Ca2+/calmodulin-dependent kinases (CaMK-II and IV/Gr) have been shown to play a critical role in calcium signaling in T cells, it was of interest to determine what effect aging has on the activation and the levels of these calcium regulating enzymes. The induction of calcineurin phosphatase activity, and CaMK-II and IV/Gr activities, were studied in splenic T cells isolated from Fischer 344 rats at 6, 15, and 24 months of age. In addition, the changes in the protein levels of these enzymes were measured by Western blot. The calcineurin phosphatase activity and CaMK-II and IV kinase activities were at a maximum after the cells were incubated with anti-CD3 antibody for 5-10 minutes. The induction of calcineurin activity by anti-CD3 and by calcium ionophore (A23187) declined 65 and 55%, respectively, between 6 and 24 months of age. The induction of CaMK-IV activity, but not CaMK-II activity by anti-CD3, was significantly less (by 54%) in T cells from old rats compared to T cells from young rats. The decline in the activation of these enzymes with age was not associated with changes in their corresponding protein levels. These results demonstrate that alterations in calcineurin phosphatase activity and CaMK-IV activity may contribute to the well-documented age-related decline in T cell function.