Interleukin-2 receptor in peripheral blood lymphocytes of Alzheimer's disease patients

Insights into T-cell dysfunction in Alzheimer's disease

T cells, the critical immune cells of the adaptive immune system, are often dysfunctional in Alzheimer's disease (AD) and are involved in AD pathology. Reports highlight neuroinflammation as a crucial modulator of AD pathogenesis, and aberrant T cells indirectly contribute to neuroinflammation by secreting proinflammatory mediators via direct crosstalk with glial cells infiltrating the brain. However, the mechanisms underlying T‐cell abnormalities in AD appear multifactorial. Risk factors for AD and pathological hallmarks of AD have been tightly linked with immune responses, implying the potential regulatory effects of these factors on T cells. In this review, we discuss how the risk factors for AD, particularly Apolipoprotein E (ApoE), Aβ, α‐secretase, β‐secretase, γ‐secretase, Tau, and neuroinflammation, modulate T‐cell activation and the association between T cells and pathological AD hallmarks. Understanding these associations is critical to provide a comprehensive view of appropriate therapeutic strategies for AD.

HLA in Alzheimer's Disease: Genetic Association and Possible Pathogenic Roles

Alzheimer's disease (AD) is commonly considered as the most prominent dementing disorder globally and is characterized by the deposition of misfolded amyloid-β (Aβ) peptide and the aggregation of neurofibrillary tangles. Immunological disturbances and neuroinflammation, which result from abnormal immunological reactivations, are believed to be the primary stimulating factors triggering AD-like neuropathy. It has been suggested by multiple previous studies that a bunch of AD key influencing factors might be attributed to genes encoding human leukocyte antigen (HLA), whose variety is an essential part of human adaptive immunity. A wide range of activities involved in immune responses may be determined by HLA genes, including inflammation mediated by the immune response, T-cell transendothelial migration, infection, brain development and plasticity in AD pathogenesis, and so on. The goal of this article is to review the recent epidemiological findings of HLA (mainly HLA class I and II) associated with AD and investigate to what extent the genetic variations of HLA were clinically significant as pathogenic factors for AD. Depending on the degree of contribution of HLA in AD pathogenesis, targeted research towards HLA may propel AD therapeutic strategies into a new era of development.

Increased T-cell reactivity and elevated levels of CD8+ memory T-cells in Alzheimer's disease-patients and T-cell hyporeactivity in an Alzheimer's disease-mouse model: implications for immunotherapy

Neuroinflammation is observed in neurodegenerative diseases like Alzheimer's disease (AD). However, a little is known about the mechanisms of neural-immune interactions. The involvement of peripheral T-cell function in AD is still far from clear, though it plays an important role in immunotherapy. The aim of this study was to determine peripheral T-cell reactivity in AD patients and in an AD mouse model. Mitogenic activation via ligation of the T-cell receptor (TCR) with PHA-L was measured in T lymphocytes from AD patients and Thy1(APP 751SL) x HMG(PS1 M146L)-transgenic mice (APP x PS1). In order to uncover failures in TCR signaling, the TCR was also bypassed by PMA and ionomycin treatment. All patients were sporadic late onset cases and the transgenic mice expressed no mutant APP in lymphocytes, so that direct interactions of mutant APP on T-cell function can be excluded. CD4+ and CD8+ T-cell showed increased reactivity (tyrosine phosphorylation, CD69 expression, and proliferation) in AD, while APP x PS1 transgenic mice displayed hyporeactive CD8+ T-cells after TCR ligation. Increased levels of CD8+ T memory cells and down regulation of CD8 receptor were found in AD and the animal model. Anergic TCR uncoupling was associated with loss of MAPK signaling (p38, ERK1 and ERK2) in APP x PS1. Our data implicate the generation of reactive memory T-cell in AD and of anergic memory T-cells in transgenic mice and should be taken into concern when designing immunotherapy.

Psychoneuroimmunology: new avenues of research for the twenty-first century

Psychoneuroimmunology (PNI) investigates the relations between the psychophysiological and immunophysiological dimensions of living beings. PNI brings together researchers in a number of scientific and medical disciplines, including psychology, the neurosciences, immunology, physiology, pharmacology, psychiatry, behavioral medicine, infectious diseases, and rheumatology. All are scientists with profound interest in interactions between the nervous and immune systems, and the relation between behavior and health. Despite the variety in domains and approaches to research, the outcome common to all research endeavors is the discovery of new information, of uncovered facts, of novel evidence, which contributes to the continuing generation of knowledge. In this paper we discuss psychoneuroimmune aspects of some conditions that are not routinely immediately associated with immunity, such as the condition of being the caregiver of somebody suffering from dementia; the effect on the brain-body modulations of aluminum, a metal that is not a component of the human body; and insomnia, a fairly common but disturbing disease, that even today lacks an effectual treatment.

Increased serum neopterin concentrations in patients with Alzheimer's disease

We measured serum neopterin concentrations in 24 patients with Alzheimer's disease (8 males, 16 females; age: 73.1+/-6.2 years; free of any infectious process) and fourteen controls of similar age (4 males, 10 females; age: 69.7+/-8.8 years). Compared to controls, significantly higher concentrations of neopterin (p< 0.01) were found in patients with Alzheimer's disease. Among patients, concentrations of neopterin were higher in those with lower mini-mental-state (p < 0.05), and an inverse correlation existed between mini-mental-state and neopterin concentrations. No such association existed with the duration of the disease. There were also significant correlations between neopterin and serum concentrations of immune activation markers such as soluble tumor necrosis factor (TNF) receptor and soluble interleukin-2 receptor (all p<0.01). Thus, increased concentrations of neopterin in serum of patients with Alzheimer's disease correlate with the severity of dementia. The data imply a chronic state of peripheral immune activation in Alzheimer's disease.

Importance of immunological and inflammatory processes in the pathogenesis and therapy of Alzheimer's disease

The contribution of autoimmune processes or inflammatory components in the etiology and pathogenesis of Alzheimer's disease (AD) has been suspected for many years. The presence of antigen-presenting, HLA-DR-positive and other immunoregulatory cells, components of complement, inflammatory cytokines and acute phase reactants have been established in tissue of AD neuropathology. Although these data do not confirm the immune response as a primary cause of AD, they indicate involvement of immune processes at least as a secondary or tertiary reaction to the preexisting pathogen and point out its driving-force role in AD pathogenesis. These processes may contribute to systemic immune response. Thus, experimental and clinical studies indicate impairments in both humoral and cellular immunity in an animal model of AD as well as in AD patients. On the other hand, anti-inflammatory drugs applied for the treatment of some chronic inflammatory diseases have been shown to reduce risk of AD in these patients. Therefore, it seems that anti-inflammatory drugs and other substances which can control the activity of immunocompetent cells and the level of endogenous immune response can be valuable in the treatment of AD patients.

Circulating cytokines in Alzheimer's disease

Immune factors may be involved in the pathophysiology of Alzheimer's disease (AD), a neurodegenerative disease. Since immune activation precedes immune-mediated processes, we measured plasma levels of four selective cytokines: interleukin-6 (IL-6), interleukin-12 (IL-12), interferon-alpha (IFN-alpha), and interferon-gamma (IFN-gamma). The level of IL-6, but not other cytokines, was significantly elevated. The increase of circulating IL-6 indicates immune activation presumably related to pathophysiology of the disease.

Correlation of cytokine secretion by mononuclear cells of Alzheimer patients and their disease stage

Cytokine secretion by human mononuclear cells (MNC) was investigated in age-matched controls and in patients with Alzheimer's disease (AD). AD patients were divided into two study groups: 'mild' and 'moderately severe'. A significant increase in interleukin-2 (IL-2) and gamma interferon (IFN-gamma) secretion was found in AD patients in the moderately severe stage of the disease, whereas in the mild stage of the disease there was a significant decrease in interleukin-3 activity (IL-3) and tumor necrosis factor (TNF) levels. No significant differences were found in the level of production of interleukin-1 (IL-1 beta). Our results demonstrate the existence of defective immune functions in AD patients which are correlated with the clinical condition of these patients.

Immunological associations in familial and non-familial Alzheimer patients and their families

A number of autoimmune diseases and immune-related conditions were investigated in a series of 100 Alzheimer patients and their families. The group was divided into those who had familial dementia of the Alzheimer type and non-familial dementia of the Alzheimer type. HLA DR3 was associated with the familial dementia of the Alzheimer type patients. Adult exposure to tuberculosis appeared to be a risk factor for familial dementia of the Alzheimer type patients. Autoimmune diseases clustered among the non-familial dementia of the Alzheimer type patients, and also among their relatives. Asthma and infertility were also significantly increased among non-familial dementia of the Alzheimer type relatives. The analysis showed that (1) autoimmunity may be important in the sporadic form of Alzheimer disease; (2) it may be possible to confer a decreased risk for Alzheimer disease among relatives when many autoimmune diseases occur in the family; (3) it may be important to assess environmental risk factors for Alzheimer disease separately in patients with familial and sporadic disease; and (4) the efficacy of drug therapies may be dependent on whether the patients have a familial or sporadic form of Alzheimer disease.