Biomedical subjects

E Masliah

Publications and source records attributed to E Masliah.

At least 19 recordsLinked to original sources

PubMed1998

Transgenic expression of IFN-alpha in the central nervous system of mice protects against lethal neurotropic viral infection but induces inflammation and neurodegeneration.

Type I IFNs, which include IFN-alpha, appear to have complex and broad-ranging actions in the central nervous system (CNS) that may result in protection or injury. To better understand these issues, we generated transgenic mice that produce IFN-alpha1 chronically from astrocytes. These glial fibrillary acidic protein-IFN-alpha transgenic mice developed a progressive inflammatory encephalopathy, with marked calcium mineralization, meninoencephalitis, gliosis, and neurodegeneration. Many features of this murine encephalopathy resembled those found in certain human encephalopathies of unknown etiology; these diseases, exemplified by Aicardi-Goutières syndrome and some viral encephalopathies, show increased intrathecal production of IFN-alpha. Our data suggest that IFN-alpha overproduction may be the primary factor initiating these human diseases. Following intracerebral infection with lymphocytic choriomeningitis virus, glial fibrillary acidic protein-IFN-alpha mice had significantly increased survival rates associated with markedly reduced virus titers and immune pathology in the brain but normal peripheral CTL responses. Therefore, the production of IFN-alpha in the CNS can be a two-edged sword that on the one hand confers protection against a lethal viral infection but on the other causes significant injury to the brain. These transgenic mice provide a novel animal model in which to further evaluate the mechanisms that underlie the diverse actions of type I IFNs in the intact CNS.

Animals↗

PubMed1998

Prostaglandin E2 induced polymerization of human alpha-1-antichymotrypsin and suppressed its protease inhibitory activity: implications for Alzheimer's disease.

Different molecular forms of alpha-1-antichymotrypsin (ACT) in sera and cerebrospinal fluids from patients with Alzheimer's disease (AD) were detected. Monomeric and polymeric ACT were observed by polyacrylamide gel electrophoresis of both sera and cerebrospinal fluids. ACT polymers were increased in AD patients with the apolipoprotein E (APOE) 4 allele. Increased levels of inactive ACT molecules were also detected in brain homogenates of patients with the APOE 4 allele. Experimental conditions promoting in vitro polymerization of ACT and the effect of polymerization on the biological activity of this serpin were also explored. Incubation of this serpin with prostaglandins of E series (PGE 2) induced ACT polymerization and decreased its activity. Amyloid beta-peptide1-42 did not significantly affected the biological activity of ACT. Inactivation of protease inhibitors by inflammatory molecules such as PGE 2 released from activated microglia in AD brains may promote amyloid deposition and neurodegeneration.

Alzheimer Disease↗

PubMed1998

Increased levels of alpha-1-antichymotrypsin in brains of patients with Alzheimer's disease correlate with activated astrocytes and are affected by APOE 4 genotype.

Levels of alpha-1-antichymotrypsin (ACT) were higher in brain homogenates of patients with Alzheimer's disease (AD) than controls. Brain tissues from the same patients and controls were immunostained with antibodies specific for microglia or astrocytes, the leukocyte common antigen (CD45) and glial fibrillary acidic protein (GFAP), respectively. Both activated CD45 and GFAP cells were increased in AD. Astroglia were divided into scattered (CD45sc) and clustered microglia (CD45cl) or scattered (GFAPsc) and clustered astrocytes (GFAPcl). Clustered cells were defined according their tendency to form focal aggregates. CD45cl and GFAPcl cells were present only in AD brain, while CD45sc and GFAPsc positive cells were present either in AD or control brains, with AD brains showing increased numbers of both cell types. A positive correlation between brain ACT levels and the number of GFAPsc positive cells was present in AD. AD patients with APOE 4 allele showed increased levels of ACT and increased CD45sc positive cells. Elevated ACT levels in the brain of AD patients could be interpreted as a metabolic response of astrocytes which might modulate the potentially deleterious activation of microglia cells.

Aged↗

PubMed1998

Human recombinant NACP/alpha-synuclein is aggregated and fibrillated in vitro: relevance for Lewy body disease.

The precursor of non-amyloid beta protein component of Alzheimer's disease amyloid (NACP/alpha-synuclein) is aggregated and fibrillated under certain conditions, i.e., increasing time lag, high temperature and low pH. These in vitro aggregates form Thioflavine-S-positive filamentous structures, reminiscent of amyloid-like fibrils. Since some Lewy bodies in Parkinson's disease display Thioflavine-S reactivity, our results may suggest that amyloidogenic properties of NACP/alpha-synuclein may play a crucial role in pathogenesis of disorders with Lewy bodies such as Parkinson's disease.

Benzothiazoles↗

PubMed1998

Differences in a dinucleotide repeat polymorphism in the tau gene between Caucasian and Japanese populations: implication for progressive supranuclear palsy.

Previous studies of a tau polymorphism in Caucasian subjects with progressive supranuclear palsy (PSP) showed an over-representation of one genotype, A0/A0, versus normal control subjects. This result suggested that tau may be playing a genetic role in the progression of PSP. This study examines whether the over-representation of A0/A0 is Caucasian-specific or universal to PSP. Unfortunately, we found this dinucleotide repeat was relatively non-polymorphic in Japanese subjects. As a result, the genotypes were virtually the same, A0/A0, between Japanese PSP and control subjects. However, this outcome, albeit negative, does suggest two possible roles of the tau gene in PSP pathogenesis: (1) the role of this dinucleotide repeat in PSP may be different between Caucasian and Japanese populations or (2) this repeat may not be causal for PSP but represents a marker for other molecular genetic risk factors within or close to the tau gene on chromosome 17.

Alzheimer Disease↗

PubMed1998

Altered long-term potentiation in the hippocampus of apolipoprotein E-deficient mice.

Recent studies suggest that apolipoprotein E (apoE) plays a neurotrophic role in the central nervous system and that an aberrant function of this molecule might result in neurodegeneration. Supporting this notion, apoE-deficient mice show neurodegenerative and cognitive alterations. To characterize physiological changes associated with synaptic damage and cognitive impairment in apoE-deficient mice, we investigated synaptic plasticity in the hippocampus of urethane anesthetized mice. Electrical stimulation was delivered to the perforant pathway and the resulting evoked field excitatory postsynaptic potential (EPSP) and population spike were recorded in the hilus. Long-term potentiation, as measured in the population spike, was reduced by 50% in apoE-deficient mice when compared to wild-type controls. In contrast, there were no significant differences in the evoked field EPSP between wild-type and apoE-deficient mice following high-frequency stimulation. These results support the notion that cognitive impairment and synaptic loss in the hippocampus of apoE-deficient mice might be associated with impaired long-term potentiation.

Animals↗

PubMed1998

Rapid fragmentation of vimentin in human skin fibroblasts exposed to tamoxifen: a possible involvement of caspase-3.

Tamoxifen (TAM), an anti-estrogen compound, is widely used for chemotherapy of breast cancer, although the molecular mechanisms underlying TAM cytotoxicity are obscure. Here, we show that TAM dramatically caused degradation of vimentin (VIM) in human skin fibroblasts, in a time and dose dependent manner. Addition of caspase-3 inhibitor, Z-DEVD-FMK, inhibited formation of some fragments of VIM, and caspase-3 was proteolytically activated by TAM treatment. Expression of functional estrogen receptors were negative in these cells, and neither transcription nor protein synthesis was required for TAM-induced degradation of VIM. Moreover, quinestrol, an ethinyl estradiol derivative, weakly degraded VIM, whereas neither estradiols nor estriol had any effects. Taken together, TAM may induce fragmentation of VIM associated with an activation of caspase-3, which may be attributed to non-genomic actions of TAM.

Antineoplastic Agents, Hormonal↗

PubMed1998

Amyloid protein precursor stimulates excitatory amino acid transport. Implications for roles in neuroprotection and pathogenesis.

Excitatory neurotransmitters such as glutamate are required for the normal functioning of the central nervous system but can trigger excitotoxic neuronal injury if allowed to accumulate to abnormally high levels. Their extracellular levels are controlled primarily by transmitter uptake into astrocytes. Here, we demonstrate that the amyloid protein precursor may participate in the regulation of this important process. The amyloid protein precursor has been well conserved through evolution, and a number of studies indicate that it may function as an endogenous excitoprotectant. However, the mechanisms underlying this neuroprotective capacity remain largely unknown. At moderate levels of expression, human amyloid protein precursors increased glutamate/aspartate uptake in brains of transgenic mice, with the 751-amino acid isoform showing greater potency than the 695-amino acid isoform. Cerebral glutamate/aspartate transporter protein levels were higher in transgenic mice than in non-transgenic controls, whereas transporter mRNA levels were unchanged. Amyloid protein precursor-dependent stimulation of aspartate uptake by cultured primary astrocytes was associated with increases in protein kinase A and C activity and could be blocked by inhibitors of these kinases. The stimulation of astroglial excitatory amino acid transport by amyloid protein precursors could protect the brain against excitotoxicity and may play an important role in neurotransmission.

Amyloid beta-Protein Precursor↗

PubMed1998

nNOS expressing neurons in the entorhinal cortex and hippocampus are affected in patients with Alzheimer's disease.

Nitric oxide is a multifunctional molecule that acts as messenger/modulator in synaptogenesis and potential neurotoxin and is synthesized by three isozymes of Nitric oxide synthase (NOS). The role of NOS in Alzheimer's disease (AD) is unclear. For example, neurons in the entorhinal cortex (EC) that are highly vulnerable to neurodegeneration in AD express low levels of NOS and while it has been suggested that the inducible form of NOS is upregulated in AD, it is still not clear if the constitutive expressed isozyme (nNOS) is involved in the process of neurodegeneration. In order to better understand the role of nNOS in the pathogenesis of AD, sections from the EC and hippocampus (HC) of AD and control cases were immunohistochemically analyzed by single- and double-immunolabeling using antibodies against nNOS and PHF-tau. Semiquantitative assessment of numbers of nNOS expressing neurons in different areas of the HC and EC showed a remarkable loss of nNOS expressing neurons in the entorhinal cortex layer II and--less severe--CA1 and CA3 of the hippocampus in patients with AD. In addition, double-immunolabeling studies revealed that nNOS is strongly associated with neurofibrillary tangles and plaques. These findings indicate that nNOS expressing neurons are highly susceptible to neurodegeneration and that nNOS might contribute to the pathogenesis of AD.

Aged↗

PubMed1998

Mechanisms of synaptic pathology in Alzheimer's disease.

Neurodegenerative disorders are characterized by damage to selective neuronal populations that could be followed or preceded by synaptic injury. Therefore, specific mutations in and other alterations of synaptic proteins might lead to particular neurodegenerative diseases. The predominant hypothesis is that these mutations result in an increased production of amyloid beta-protein 1-42 which acts as a neurotoxin. However, it could also be postulated that amyloid precursor protein might play an important role in synaptic function and neuronal maintenance and that its abnormal activity may lead to neurodegeneration. Recent studies have shown that amyloid precursor protein has an important role in regulating glutamate levels at the synaptic site by modulating the activity of glutamate transporters. The objectives of this manuscript are to highlight recent data supporting the hypothesis that neurodegeneration in Alzheimer's disease might be the combined result of abnormal protective activity of amyloid precursor protein and amyloid beta-protein toxicity.

Alzheimer Disease↗

PubMed1998

Late-onset chronic inflammatory encephalopathy in immune-competent and severe combined immune-deficient (SCID) mice with astrocyte-targeted expression of tumor necrosis factor.

To examine the role of tumor necrosis factor (TNF)-alpha in the pathogenesis of degenerative disorders of the central nervous system (CNS), transgenic mice were developed in which expression of murine TNF-alpha was targeted to astrocytes using a glial fibrillary acidic protein (GFAP)-TNF-alpha fusion gene. In two independent GFAP-TNFalpha transgenic lines (termed GT-8 or GT-2) adult (>4 months of age) animals developed a progressive ataxia (GT-8) or total paralysis affecting the lower body (GT-2). Symptomatic mice had prominent meningoencephalitis (GT-8) or encephalomyelitis (GT-2) in which large numbers of B cells and CD4+ and CD8+ T cells accumulated at predominantly perivascular sites. The majority of these lymphocytes displayed a memory cell phenotype (CD44high, CD62Llow, CD25-) and expressed an early activation marker (CD69). Parenchymal lesions contained mostly CD45+ high, MHC class II+, and Mac-1+ cells of the macrophage microglial lineage with lower numbers of neutrophils and few CD4+ and CD8+ T cells. Cerebral expression of the cellular adhesion molecules ICAM-1, VCAM-1, and MAdCAM as well as a number of alpha- and beta-chemokines was induced or upregulated and preceded the development of inflammation, suggesting an important signaling role for these molecules in the CNS leukocyte migration. Degenerative changes in the CNS of the GFAP-TNFalpha mice paralleled the development of the inflammatory lesions and included primary and secondary demyelination and neurodegeneration. Disease exacerbation with more extensive inflammatory lesions that contained activated cells of the macrophage/microglial lineage occurred in GFAP-TNFalpha mice with severe combined immune deficiency. Thus, persistent astrocyte expression of murine TNF-alpha in the CNS induces a late-onset chronic inflammatory encephalopathy in which macrophage/microglial cells but not lymphocytes play a central role in mediating injury.

Animals↗

PubMed1998

Keratinocyte growth factor decreases pulmonary edema, transforming growth factor-beta and platelet-derived growth factor-BB expression, and alveolar type II cell loss in bleomycin-induced lung injury.

Keratinocyte growth factor (KGF), a potent growth factor for type II pneumocytes and Clara cells, has been shown to prevent the end-stage pulmonary fibrosis and mortality in a rat model of bleomycin-induced lung injury. In this study, protective effects of KGF were explored during the earlier course of bleomycin-induced lung injury by studying protein exudation in alveolar edema fluids, pulmonary expression of transforming growth factor-beta (TGF beta) and platelet-derived growth factor-BB (PDGF-BB), and changes in type II pneumocytes and Clara cells after i.t. (intratracheal) bleomycin injection following KGF- or saline-pretreatment in rats. Total protein in bronchoalveolar lavage (BAL) fluids after bleomycin injury from KGF-pretreated rats was significantly lower than the levels in saline-pretreated rats. TGF beta protein in BAL fluids which peaked at day 3 after i.t. bleomycin in saline-pretreated lungs was not significantly increased at any time points in KGF-pretreated rats. PDGF-BB protein in whole lung tissues of KGF-pretreated rats also remained near normal throughout the course after i.t. bleomycin, in contrast to the significant increase in saline-pretreated rats. Numbers of type II pneumocytes and Clara cells in KGF-pretreated lungs after a high dose of bleomycin were close to the normal in intact lungs. At the same dose of bleomycin injury, type II pneumocytes in saline-pretreated lungs were markedly decreased, while the number of Clara cells in these rats was relatively preserved as the pre-injury level. In conclusion, KGF prevents bleomycin-induced end-stage pulmonary injury and mortality probably at least partly by decreasing protein-rich pulmonary edema, protein expression of fibrogenic cytokines TGF beta and PDGF-BB, and type II cell loss during the course of lung injury.

Animals↗

PubMed1998

Novel role of human CD4 molecule identified in neurodegeneration.

The human CD4 molecule (hCD4) is expressed on T lymphocytes and macrophages and acts as a key component of the cellular receptor for HIV. At baseline, hCD4 transgenic mice expressed hCD4 on microglia, the resident mononuclear phagocytes of the brain, and showed no neuronal damage. Activation of brain microglia by peripheral immune challenges elicited neurodegeneration in hCD4 mice but not in nontransgenic controls. In post-mortem brain tissues from AIDS patients with opportunistic infections, but without typical HIV encephalitis, hCD4 expression correlated with neurodegeneration. We conclude that hCD4 may function as an important mediator of indirect neuronal damage in infectious and immune-mediated diseases of the central nervous system.

AIDS-Related Opportunistic Infections↗

PubMed1998

Expression pattern of synucleins (non-Abeta component of Alzheimer's disease amyloid precursor protein/alpha-synuclein) during murine brain development.

The non-Abeta component of Alzheimer's disease amyloid precursor protein (NACP) is predominantly a neuron-specific presynaptic protein that may play a central role in neurodegeneration because NACP fragments are found in Alzheimer's disease amyloid and a mutation in the NACP gene is associated with familial Parkinson's disease. In addition, NACP may play an important role during synaptogenesis and CNS development. To understand better the patterns of NACP expression during development, we analyzed the levels of this protein as well as the levels of another synaptic protein (synaptophysin) by ribonuclease protection assay, western blotting, and immunocytochemistry in fetal, juvenile, and adult mouse brain. From embryonic day 12 to 15, there was a slight increase, which was then followed by a more dramatic increase at later time points. Immunocytochemical staining for NACP increases throughout these stages as well. Although NACP appeared early in CNS development, synaptophysin levels started to rise at a later stage. These findings support the contention that NACP might be important for CNS development. Furthermore, the cytosolic component of NACP precedes the particulate component in development, indicating that a redistribution of the protein to the membrane fraction may be important for events later in neuronal development and in synaptogenesis.

Alzheimer Disease↗

PubMed1998

Distribution of brain HIV load in AIDS.

Approximately one quarter of patients with AIDS develop severe cognitive deficits called HIV-associated dementia complex (ADC). There is some controversy regarding the importance of viral load in mediating neurologic disease. With the advent of sensitive, quantitative and reproducible RNA assays for HIV load in plasma and CSF, we quantified viral load in brains from 10 autopsied HIV-infected subjects and 2 non-infected controls. The new quantitative HIV RNA assays showed general agreement with previously used semi-quantitative immunocytochemical assessments of HIV envelope protein, and were performed without professional subjective interpretation. All cases with very high levels of HIV in the CSF, had high overall levels in the brain, suggesting that CSF viral loads exceeding 10(6) copies per mL may be a surrogate marker of high viral load in the brain. Levels of virus in the spleen showed no clear association with those found in the brain. HIV RNA was not uniformly distributed throughout the brain. Selective regions, including basal ganglia and hippocampus, showed higher levels of virus than the cerebellar cortex and mid-frontal cortical gray matter. Assessment of overall brain viral load requires careful attention to regional quantitation.

Acquired Immunodeficiency Syndrome↗

PubMed1998

Association of CYP2D microsatellite polymorphism with Lewy body variant of Alzheimer's disease.

OBJECTIVE: To examine the genetic association of CYP2D6 locus with Lewy body variant (LBV) and Parkinson's disease (PD). METHODS: Allelic association was studied in patients with pure AD, LBV, and PD by using the CYP2D microsatellite, the (dG-dT)n dinucleotide repeat (n=16 to 27) located between CYP2D8P and CYP2D7 genes, and the CYP2D6 B and D mutations. RESULTS: We found overrepresentation of the alleles longer than 21 repeat (the long-type alleles) in LBV (allele frequency, 0.313) (odds ratio=1.99, p=0.019 by chi2 test) and in PD (0.298) (odds ratio=1.86, p=0.037), but not in pure AD (0.196), compared with the age-matched control (0.186). Strong association was noted of the long-type alleles with the CYP2D6 B mutation (odds ratio=88.50, p < 0.001 by Fisher's exact test), but not with the D mutation or the deletion of CYP2D6 gene. CONCLUSIONS: The CYP2D locus is closely associated with LBV and PD. The CYP2D6 B mutation may be involved in pathogenesis of LBV and PD in a dominant-negative manner, or in the linkage disequilibrium of the CYP2D microsatellite to another pathogenic gene locus.

Aged↗

PubMed1998

Abnormal accumulation of NACP/alpha-synuclein in neurodegenerative disorders.

The precursor of the non-Abeta component of Alzheimer's disease amyloid (NACP) (also known as a-synuclein) is a presynaptic terminal molecule that accumulates in the plaques of Alzheimer's disease. Recent studies have shown that a mutation in NACP is associated with familial Parkinson's disease, and that Lewy bodies are immunoreactive with antibodies against this molecule. To clarify the patterns of accumulation and differences in abnormal compartmentalization, we studied NACP immunoreactivity using double immunolabeling and laser scanning confocal microscopy in the cortex of patients with various neurodegenerative disorders. In Lewy body variant of Alzheimer's disease, diffuse Lewy body disease, and Parkinson's disease, NACP was found to immunolabel cortical Lewy bodies, abnormal neurites, and dystrophic neurites in the plaques. Double-labeling studies showed that all three of these neuropathological structures also contained ubiquitin, synaptophysin, and neurofilament (but not tau) immunoreactivity. In contrast, neurofibrillary tangles, neuropil threads, Pick bodies, ballooned neurons, and glial tangles (most of which were tau positive) were NACP negative. These results support the view that NACP specifically accumulates in diseases related to Lewy bodies such as Lewy body variant of Alzheimer's disease, diffuse Lewy body disease, and Parkinson's disease and suggests a role for this synaptic protein in the pathogenesis of neurodegeneration.

Aged↗

PubMed1998

Abnormal distribution of the non-Abeta component of Alzheimer's disease amyloid precursor/alpha-synuclein in Lewy body disease as revealed by proteinase K and formic acid pretreatment.

The precursor of the non-Abeta component of Alzheimer's disease amyloid (NACP) (also known as alpha-synuclein) is a presynaptic terminal molecule that abnormally accumulates in the plaques of Alzheimer's disease (AD) and in the Lewy bodies (LBs) of Lewy body variant of AD, diffuse Lewy body disease, and Parkinson's disease. To better understand the distribution of NACP/alpha-synuclein and its fragments in the LB-bearing neurons and neurites, as well as to clarify the patterns of NACP/alpha-synuclein compartmentalization, we studied NACP/alpha-synuclein immunoreactivity using antibodies against the C-terminal, N-terminal, and NAC regions after Proteinase K and formic acid treatment in the cortex of patients with LBs. Furthermore, studies of the subcellular localization of NACP/alpha-synuclein within LB-bearing neurons were performed by immunogold electron microscopy. These studies showed that the N-terminal antibody immunolabeled the LBs and dystrophic neurites with great intensity and, to a lesser extent, the synapses. In contrast, the C-terminal antibody strongly labeled the synapses and, to a lesser extent, the LBs and dystrophic neurites. Whereas Proteinase K treatment enhanced NACP/alpha-synuclein immunoreactivity with the C-terminal antibody, it diminished the N-terminal NACP/alpha-synuclein immunoreactivity. Furthermore, formic acid enhanced LB and dystrophic neurite labeling with both the C- and N-terminal antibodies. In addition, whereas without pretreatment only slight anti-NAC immunoreactivity was found in the LBs, formic acid pretreatment revealed an extensive anti-NAC immunostaining of LBs, plaques, and glial cells. Ultrastructural analysis revealed that NACP/alpha-synuclein immunoreactivity was diffusely distributed within the amorphous electrodense material in the LBs and as small clusters in the filaments of LBs and neurites. These results support the view that aggregated NACP/alpha-synuclein might play an important role in the pathogenesis of disorders associated with LBs.

Cadaver↗