Antibodies recognizing cholinergic neurons and thyroglobuline are found in the cerebrospinal fluid of a subgroup of patients with Alzheimer's disease

Cerebrospinal fluid antimicroglial antibodies in Alzheimer disease: A putative marker of an ongoing inflammatory process

Immunocompetent microglia play an important role in the pathogenesis of Alzheimer's disease (AD). Antimicroglial antibodies in the cerebrospinal fluid (CSF) in clinically diagnosed AD patients have been previously recorded. Here, we report the results of the analysis of the CSF from 38 autopsy cases: 7 with definite AD; 14 with mild and 10 with moderate Alzheimer's type pathology; and 7 controls. Antimicroglial antibodies were identified in 70% of patients with definite AD, in 80% of patients with moderate and in 28% of patients with mild Alzheimer's type pathology. CSF antimicroglial antibodies were not observed in any of the control cases. The results show that CSF antimicroglial antibodies are present in the majority of patients with definite AD and also in cases with moderate Alzheimer's type changes. They may also indicate dysregulation of microglial function. Together with previous observations, these findings indicate that compromised immune defense mechanisms play an important role in the pathogenesis of AD.

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.

Anti-brain spectrin immunoreactivity in Alzheimer's disease: degradation of spectrin in an animal model of cholinergic degeneration

In a previous work, we described the existence of anti-brain spectrin auto antibodies in Alzheimer's disease (AD) patients (J. Neuroimmunol. 68 (1996) 39-44). In this report, we further support our previous observations, showing that sera from 9 out of 18 AD patients, but none of 14 control subjects, immunoreacted with spectrin synthesized by PC12 cells. In addition, degradation of brain spectrin was found to be greatly enhanced in the frontal cortex of rats subjected to an animal model of cholinergic degeneration. Our data suggest that spectrin degradation and generation of anti-spectrin auto antibodies may be related to the cholinergic degeneration encountered in AD.

Changes of intrathecal immunoglobulin synthesis in various types of dementias

Our examinations were finished on 80 patients with different dementia forms. We specified the concentration of liquor immunoglobulins with the nephelometrical method, and concluded the presence of intrathecal immunoglobulin (IgG, IgM and IgA) synthesis on the basis of the Link index. In the cases of senile dementia, SDAT and AD, we found altered blood-brain barrier function. We detected intrathecal IgG and IgA synthesis at AD patients, while the synthesis of all the three immunoglobulins was characteristic for the Jakob-Creutzfeld disease. On the basis of our results, we came to the conclusion that, at the different dementias, the immunopathological occurrences play different roles in the development of the disease.

Alzheimer's disease cerebrospinal fluid antibodies display selectivity for microglia. Investigations with cell cultures and human cortical biopsies

Previous investigations demonstrated that the cerebrospinal fluid (CSF) from Alzheimer's disease (AD) patients contains antibodies that recognize specific neuronal populations in the adult rat central nervous system (CNS). These findings suggest a pathogenic role for immunological aberrations in this disorder. To determine if antibodies may provide a means to differentially diagnose the dementias, CSF from a diversified dementia population was screened against the developing rat CNS and a cell culture system. Markings produced by AD CSF were distinctly different from those of vascular dementias (VAD) against the developing rat CNS. More importantly, some AD CSF recognized amoeboid microglia. The recognition of amoeboid microglia by antibodies in AD CSF is particularly interesting since these cells proliferate in response to nervous system disease and also engulf debris. A cell culture technique was developed to allow the rapid screening of CSF antibodies. Patient CSF produced five different types of markings in the cell culture: microglia, glioblasts, fibers, nonspecific, or negative. Correlations with these structures and the diagnosis of four different dementia populations revealed that, in comparison to the other groups, AD CSF displayed remarkable selectivity toward microglial cells. Cortical biopsies from patients suspected to have AD were incubated with the patient's own CSF and that of confirmed AD patients. Both CSF samples recognized microglial cells in the patient's cortical biopsy. The same CSF samples incubated against normal human cortical autopsy or a biopsy from a 3-mo-old child displayed negative immunoreactivity. These three approaches suggest that the presence of CSF microglial antibodies may be a means to distinguish AD patients from other dementias. The results add further support to the widely growing concept that inflammation and similar immune mechanisms may contribute to AD pathogenesis.

Reduction of thyroid hormone receptor c-ERB A alpha mRNA levels in the hippocampus of Alzheimer as compared to Huntington brain

A history of thyroid dysfunction has been cited as a possible risk factor for Alzheimer's disease (AD). Neurologic symptoms displayed by hypothyroid patients resemble, in part, those manifested by Alzheimer patients. To determine if a relationship exists between thyroid hormone receptor message levels and AD, in situ hybridization with tritiated antisense RNA probes for thyroid hormone receptors was used to examine the expression of these genes in Alzheimer and Huntington brain tissue. Message levels for a thyroid hormone receptor highly expressed in brain (c-ERB A alpha) was reduced by 52% in CA1 and 43% in CA2 in Alzheimer hippocampus as compared to Huntington controls. In contrast, message levels for another form of thyroid hormone receptor (c-ERB A beta 1) in Alzheimer hippocampus were not significantly different from Huntington controls. Temporal and cerebellar levels of c-ERB A alpha were elevated by 1.6-fold whereas temporal but not cerebellar levels of c-ERB A beta 1 were elevated 2.0-fold in Alzheimer brain. There was no correlation between thyroid hormone receptor levels and brain weight, autopsy interval, patient age, or the extent of neurofibrillary degeneration. Instead, decreased thyroid hormone receptor mRNA levels in Alzheimer-affected hippocampus were due to an increase in the percentage of neurons expressing lower message levels for these proteins.

Antibody in the CSF of patients with multiple system atrophy reacts specifically with rat locus ceruleus

Idiopathic chronic autonomic dysfunction may occur as pure autonomic failure (PAF) or in association with multiple system atrophy (MSA). CSF immunoreactivity to rat locus ceruleus occurred in a significantly greater number of samples from MSA patients compared to control subjects or patients with PAF. Other brain regions infrequently showed immunoreactivity. These findings suggest that degeneration in MSA may release antigen(s) that induce antibodies against locus ceruleus neurons. Further studies are required to determine whether immune abnormalities play a pathogenetic role in MSA. Lack of CSF immunoreactivity in PAF is consistent with primarily peripheral involvement.

Antibodies in the cerebrospinal fluid of some Alzheimer's disease patients recognize amoeboid microglial cells in the developing rat central nervous system

Previous investigations have demonstrated that the cerebrospinal fluid from Alzheimer's disease patients contains antibodies that recognize specific neuronal populations in the adult rat central nervous system. These findings suggest a pathogenic role for immunological aberrations in this disorder. In the present report the investigation of antibodies in the cerebrospinal fluid of Alzheimer's disease patients was extended to developing rat central nervous system. The antibody in cerebrospinal fluid from Alzheimer's disease patients recognized entirely different types of antigens in the developing rat central nervous system as compared to adult rat central nervous system. One of the most remarkable differences was the recognition of amoeboid microglial cells. Diverse morphological forms of amoeboid microglial cells were observed, located mainly in the cavum septum pellucidum and in the corpus callosum. Electron microscopy revealed that the cerebrospinal fluid antibody from the Alzheimer's disease patients recognized specific membrane receptors in the macrophagic microglia. The unexpected recognition of amoeboid microglia by antibodies in Alzheimer's disease-cerebrospinal fluid is particularly interesting since these cells proliferate in response to nervous system disease and also engulf debris. The results add further support to the concept that inflammation and similar immune mechanisms may contribute to Alzheimer's disease pathogenesis.

Animal models of age-related dementia: neurobehavioral dysfunctions in autoimmune mice

The development of strategies for treatment of Alzheimer's disease and other age-associated dementias is an important goal of research in the neurosciences. It is suggested that advances in understanding of the etiology of those disorders would provide the most obvious avenues to development of preventative treatments. Research findings from both clinical investigations and studies of animal models are presented which suggest a neuroimmunologic component in age-associated dementia. Clinical studies suggest an association between dementia and brain-reactive autoantibodies in subsets of patients with Alzheimer's disease. Studies of mice suggest that: 1) when compared with normal genotypes, mutant mice with accelerated autoimmunity show learning and memory impairments at earlier chronological ages; 2) the learning and memory deficits of autoimmune and normal mice are qualitatively similar; 3) the behavioral deficits of normal aged and autoimmune mice are sensitive to similar pharmacologic interventions. Overall, these findings suggest that intervention strategies targeting the immune system might be useful in the treatment or prevention of aging-associated dementia. Autoimmune mice would be useful as models for the development and testing of such immune-based interventions.

Investigations on auto-antibodies in Alzheimer's and Parkinson's diseases, using defined neuronal cultures

In immunocytochemical studies, the CSF from Parkinson disease (PD) patients and from Alzheimer disease (AD) patients were investigated for the presence of neuron specific antibodies using dopaminergic and cholinergic neuronal cultures from embryonic rat brain, respectively. Dopamine containing cell bodies were labelled by Parkinsonian CSF-IgG, while cholinergic neurons, identified with a-NGF-receptor antibodies, were recognized by CSF from AD-patients. The CSF from PD-patients was investigated after autologous adrenal transplantation. CSF was removed 7 d, 5 months and 1 year after operation. When added to 18 d neuronal cultures for 3 d, the 7 d CSF caused neuronal cell and a glial reaction. The 4 months CSF caused cell death, but markedly less than the 7 d CSF. One year after transplantation the CSF had no toxic effects; these cultures were similar to control cultures. It is concluded that CSF from PD patients may contain aggressive IgG-species specific for DA neurons, and that the amount of such antibodies decrease after adrenal transplant operations. It is suggested that neurodegenerative diseases may become aggravated by autoimmune reactions.

Autoimmunity and age-associated cognitive decline

It is suggested that the immune system may play a role in the etiology of age-associated cognitive decline and/or Alzheimer's disease. The relationship between brain-reactive antibodies (BRA) and age-associated cognitive dysfunction is reviewed and discussed. A parallel relationship between BRA increases with age and decline of avoidance learning capacity is described in mouse models. Transfer of immunity from old to young mice was found to accelerate both age-related formation of brain-reactive antibodies and age-related decline of avoidance learning capacity. Short-lived mouse genotypes with accelerated autoimmunity were found to show accelerated age-related declines in their ability to acquire an avoidance response when compared with nonautoimmune mice. Overall, these findings suggest that the immune system could be an important target for development of intervention strategies aimed at extending the intellectually competent period of life. Mice in which autoimmunity is accelerated may be useful as models for the development of such interventions.