Age-related changes of apoptotic cell death in human lymphocytes

Apoptosis seems to be involved in immunosenescence associated with aging. Moreover, in lymphocytes (PBL) of patients with Alzheimer's disease, an increased susceptibility to the apoptotic pathway has been described possibly due to impaired protection of oxidative stress. Accordingly, it seemed to be of particular interest to investigate the contribution of normal aging to the susceptibility from human lymphocytes to programmed cell death. We could show that PBL from elderly individuals (>60 years) accumulate apoptosing cells to a significant higher extent in spontaneous and activation-induced cell death compared to younger controls (<35 years). Treatment with the oxidative stressor 2-deoxy-D-ribose or with agonistic-CD95-antibody pronounced this effect even more implicating a higher sensitivity to reactive oxygen species and a higher functional CD95 expression, respectively. In addition, expression of the activation markers HLA-DR and CD95 was significantly increased in CD3+-cells of aged subjects, while expression of CD25 did not seem to be affected by age. Expression of Bcl-2 was increased in aging and correlated with the number of apoptotic cells

Age-related increase of oxidative stress-induced apoptosis in mice prevention by Ginkgo biloba extract (EGb761)

Enhanced apoptosis and elevated levels of reactive oxygen species (ROS) play a major role in aging. In addition, several neurodegenerative diseases are associated with increased oxidative stress and apoptosis in neuronal tissue. Antioxidative treatment has neuro-protective effects. The aim of the present study was to evaluate changes of susceptibility to apoptotic cell death by oxidative stress in aging and its inhibition by the antioxidant Ginkgo biloba extract EGb761. We investigated basal and ROS-induced levels of apoptotic lymphocytes derived from the spleen in young (3 months) and old (24 months) mice. ROS were induced by 2-deoxy-D-ribose (dRib) that depletes the intracellular pool of reduced glutathione. Lymphocytes from aged mice accumulate apoptotic cells to a significantly higher extent under basal conditions compared to cells from young mice. Treatment with dRib enhanced this difference, implicating a higher sensitivity to ROS in aging. Apoptosis can be reduced in vitro by treatment with EGb761. In addition, mice were treated daily with 100mg/kg EGb761 per os over a period of two weeks. ROS-induced apoptosis was significantly reduced in the EGb761 group. Interestingly, this effect seemed to be more pronounced in old mice

Age-related impairment of human T lymphocytes' activation: specific differences between CD4+ and CD8+ subsets

The relevance of physiological immune aging is of great interest with respect to determining disorders with pathologic immune function in aging individuals. In recent years, the relevance of changes in peripheral lymphocytes in age-associated neurologic diseases has become more evident. Due to the lack of immunological studies, covering more than one event after mitogenic activation, we envisaged a new concept in the present study, aiming to investigate several events, starting from T cell receptor (TCR) ligation up to T cell proliferation. In addition, we addressed the question whether changes are present in the subsets (CD4, CD8) with aging. Phosphorylation of tyrosine residues declines with increasing age in CD4+ cells. Fewer levels of CD69 positive cells after 4 h mitogenic activation, altered expression of cytokines (IL2, IFN-gamma and TNF-alpha; 22 h) and lower proliferation (72 h) were determined in aging. Moreover, it could be shown that CD8+ lymphocytes react more effectively to mitogenic stimulation with reference to CD69 expression and proliferation in both age groups (60 years old). These data indicate that T cell activation, mediated by TCR engagement, is significantly impaired in aging and both subsets are affected. However, bypassing the TCR does not fully restore T cell function, indicating that there are more mechanisms involved than impaired signal transduction through TCR only. The results will be discussed in relation to their relevance in neurodegenerative and psychiatric disorders

Reduced antioxidant enzyme activity in brains of mice transgenic for human presenilin-1 with single or multiple mutations

Alzheimer's disease-related mutations in the presenilin-1 gene (PS1) are leading to an elevated production of neurotoxic beta-amyloid 1-42 and may additionally enhance oxidative stress. Here, we provide in vivo evidence indicating that brains of transgenic mice expressing different human Alzheimer-linked PS1 mutations exhibit a reduced activity of two antioxidant enzymes. For this purpose, mice transgenic for human PS1 and for single and multiple PS1 mutations were generated. Mice with multiple PS1 mutations showed a significantly decreased activity of the antioxidant enzymes Cu/Zn superoxide dismutase and glutathione reductase already at an age of 3-4 months. As expected, this effect was less pronounced for the mice with a single PS1 mutation. By contrast, animals bearing normal human PS1 showed significantly elevated enzyme activities relative to non-transgenic littermate controls

Effects of EGb 761® Ginkgo biloba extract on mitochondrial function and oxidative stress

As major sources of reactive oxygen species (ROS), mitochondrial structures are exposed to high concentrations of ROS and may therefore be particularly susceptible to oxidative damage. Mitochondrial damage could play a pivotal role in the cell death decision. A decrease in mitochondrial energy charge and redox state, loss of transmembrane potential (depolarization), mitochondrial respiratory chain impairment, and release of substances such as calcium and cytochrome c all contribute to apoptosis. These mitochondrial abnormalities may constitute a part of the spectrum of chronic oxidative stress in Alzheimer's disease. Accumulation of amyloid beta (Abeta) in form of senile plaques is also thought to play a central role in the pathogenesis of Alzheimer's disease mediated by oxidative stress. In addition, increasing evidence shows that Abeta generates free radicals in vitro, which mediate the toxicity of this peptide. In our study, PC12 cells were used to examine the protective features of EGb 761(definition see editorial) on mitochondria stressed with hydrogen peroxide and antimycin, an inhibitor of complex III. In addition, we investigated the efficacy of EGb 761 in Abeta-induced MTT reduction in PC12 cells. Moreover, we examined the effects of EGb 761 on ROS levels and ROS-induced apoptosis in lymphocytes from aged mice after in vivo administration. Here, we will report that EGb 761 was able to protect mitochondria from the attack of hydrogen peroxide, antimycin and Abeta. Furthermore, EGb 761 reduced ROS levels and ROS-induced apoptosis in lymphocytes from aged mice treated orally with EGb 761 for 2 weeks. Our data further emphasize neuroprotective properties of EGb 761, such as protection against Abeta-toxicity, and antiapoptotic properties, which are probably due to its preventive effects on mitochondria

Alzheimer's disease-like alterations in peripheral cells from presenilin-1 transgenic mice

Many cases of early-onset inherited Alzheimer's disease (AD) are caused by mutations in the presenilin-1 (PS1) gene. Expression of PS1 mutations in cell culture systems and in primary neurons from transgenic mice increases their vulnerability to cell death. Interestingly, enhanced vulnerability to cell death has also been demonstrated for peripheral lymphocytes from AD patients. We now report that lymphocytes from PS1 mutant transgenic mice show a similar hypersensitivity to cell death as do peripheral cells from AD patients and several cell culture systems expressing PS1 mutations. The cell death-enhancing action of mutant PS1 was associated with increased production of reactive oxygen species and altered calcium regulation, but not with changes of mitochondrial cytochrome c. Our study further emphasizes the pathogenic role of mutant PS1 and may provide the fundamental basis for new efforts to close the gap between studies using neuronal cell lines transfected with mutant PS1, neurons from transgenic animals, and peripheral cells from AD patients. Copyright 2001 Academic Press

Impact of aging : sporadic, and genetic risk factors on vulnerability to apoptosis in Alzheimer's disease

The identification of specific genetic (presenilin-1 [PS1] and amyloid precursor protein [APP] mutations) and environmental factors responsible for Alzheimer's disease (AD) has revealed evidence for a shared pathway of neuronal death. Moreover, AD-specific cell defects may be observed in many other nonneuronal cells (e.g., lymphocytes). Thus, lymphocytes may serve as a cellular system in which to study risk factors of sporadic, as well as genetic AD in vivo. The aim of our present study was to clarify whether lymphocytes bearing genetic or sporadic risk factors of AD share an increased susceptibility to cell death. Additionally we examined whether a cell typespecific vulnerability pattern was present and how normal aging, the main risk factor of sporadic AD, contributes to changes in susceptibility to cell death. Here, we report that lymphocytes affected by sporadic or genetic APP and PS1 AD risk factors share an increased vulnerability to cell death and exhibit a similar cell type-specific pattern, given that enhanced vulnerability was most strongly developed in the CD4+ T-cell subtype. In this paradigm, sporadic risk factors revealed the highest impact on cell type-specific sensitivity of CD4+ T cells to apoptosis. In contrast, normal aging results in an increased susceptibility to apoptosis of both, CD4+ and CD8+ T cells

Enhanced ROS-generation in lymphocytes from Alzheimer’s patients

Introduction: Reactive oxygen species (ROS) have been implicated in neurodegeneration and seem to be involved in the physiology and pathophysiology of several diseases, including normal aging and Alzheimer’s disease (AD). Enhanced ROS production in aging or AD is not restricted to the brain, but can also been seen in several peripheral tissues. The objective of the present study was to evaluate whether the mechanisms involved in the generation of oxidative stress in normal senescence and Alzheimer’s disease are identical or not. Methods: We analysed intracellular basal levels of ROS in lymphocytes from AD patients and healthy young and aged not-demented subjects as well as ROS levels following stimulation with d-ribose and staurosporine in all three groups. ROS levels were measured by flow cytometry using the intracellular fluorescence dye dihydrorhodamine123 (DHR123). Results: Our study shows that AD lymphocytes have increased basal levels of ROS, low susceptibility to ROS stimulation by 2-deoxy-D-ribose (dRib) and an increased response to staurosporine when compared with age-matched controls. Discussion: The data suggest that the defect(s) responsible for enhanced ROS production in AD may involve different or additional biological pathways than those involved in enhanced ROS generation during aging

Relationship between chronic pain and cognition in cognitively intact older persons and patients with Alzheimer's disease; the need to control for mood

Background: Brain areas that are involved in cognition and mood also play a role in pain processing. Objective: The goal of the present study was to examine the relationship between chronic pain and cognition [executive functions (EF) and memory], while controlling for mood, in cognitively intact older persons and in patients with Alzheimer's disease (AD). Methods: Two groups of subjects participated: 20 older persons without dementia and 19 patients in an early stage of probable AD who suffered from arthrosis/arthritis. Pain intensity and pain affect were assessed by the Colored Analogue Scale for Pain Intensity and for Pain Affect, the Faces Pain Scale (FPS) and the Number of Words Chosen-Affective (NWC-A). Level of depression and anxiety were evaluated by questionnaires. EF and memory were assessed by neuropsychological tests. Results: The results show that significant correlations between specific cognitive functions, pain intensity and pain affect were lacking in the cognitively intact older persons. Cognition, in particular memory, appeared to be related to depressive symptoms. In contrast, a significant positive correlation was observed between EF, pain intensity and pain affect measured by the FPS in the AD group. Conclusions: Although older persons with depression were excluded, in studies on pain and cognition one should control for the presence of depressive symptoms in older persons with and without dementia. Copyright © 2008 S. Karger AG