An autopsy report of three kindred in a Gerstmann-Sträussler-Scheinker disease P105L family with a special reference to prion protein, tau, and beta-amyloid.

INTRODUCTION: Gerstmann-Sträussler-Scheinker disease P105L (GSS105) is a rare variant of GSS caused by a point mutation of the prion protein (PrP) gene at codon 105 (proline to leucine substitution). It is clinically characterized by spastic paraparesis and dementia and histopathologically defined by PrP-plaques in the brain. This report describes a clinicopathological analysis of three autopsied kindred from a Japanese GSS105 family, plus a topological analysis of PrP, hyperphosphorylated tau (p-tau), and beta-amyloid (Aß). METHODS: Using paraffin-embedded sections, we applied histology and single- and multiple-labeling immunohistochemistry for PrP, p-tau, and Aß to the three cases. Comparative semi-quantitative analyses of tissue injuries and PrP-plaques were also employed. RESULTS: Case 1 (45 years old (yo)) and Case 2 (56 yo) are sisters, and Case 3 (49 yo) is the son of Case 2. Case 1 and Case 2 presented with spastic paraparesis followed by dementia, whereas Case 3 presented, not with spastic paraparesis, but with psychiatric symptoms. In Case 1 and Case 2, the brain showed tissue injuries with many PrP-plaques in the cerebral cortices, and the pyramidal tract showed myelin loss/pallor. In Case 3, the brain was least degenerated with a number of PrP-plaques; however, the pyramidal tract remained intact. In addition, p-tau was deposited in all cases, where p-tau was present in or around PrP-plaques. By double-labeling immunohistochemistry, the colocalization of p-tau with PrP-plaques was confirmed. Moreover in Case 2, Aß was deposited in the cerebral cortices. Interestingly, not only p-tau but also Aß was colocalized with PrP-plaques. In all cases, both three repeat tau and four repeat tau were associated with PrP-plaques. CONCLUSIONS: The clinicopathological diversity of GSS105, which is possible even in the same family, was ascertained. Not only p-tau but also Aß could be induced by PrP ("secondary degeneration"), facilitating the kaleidoscopic symptoms of GSS.

Variable expression of microglial DAP12 and TREM2 genes in Nasu-Hakola disease.

Nasu-Hakola disease (NHD) is a form of presenile dementia associated with sclerosing leukoencephalopathy and polycystic lipomembranous osteodysplasia. This extremely rare inherited disease is caused by mutations in either DAP12 or TREM2. The present study was designed to assess the relationship between DAP12/TREM2 genotype, mRNA and protein expression levels by both Western blotting and immunohistochemistry, and the tissue distribution and pathomorphological phenotype of the microglia. Molecular genetic testing performed in three NHD cases confirmed that two cases had mutations in DAP12 and that one case carried a mutation in TREM2. Protein levels were analyzed in four cases. Interestingly, significant DAP12 expression was found in numerous microglia in one NHD case with a homozygous DAP12 single-base substitution, and both real-time PCR and Western blotting confirmed the finding. In contrast, levels of both DAP12 and TREM2, respectively, were much lower in the other cases. Immunohistochemistry using established microglial markers revealed consistently mild activation of microglia in the cerebral white matter although there was no or only little expression of DAP12 in three of the NHD cases. The highly different expression of DAP12 represents the first description of such variable expressivity in NHD microglia. It raises important questions regarding the mechanisms underlying dementia and white matter damage in NHD.

Lesions of cortical GABAergic interneurons and acetylcholine neurons in xeroderma pigmentosum group A.

Xeroderma pigmentosum (XP) is a rare genetic disorder caused by inherited disturbances in the nucleotide excision repair system; patients with XP groups A (XP-A), B, D, and G were shown to have progressive neurological disturbances. Particularly, XP-A patients, which account for approximately half of Japanese XP patients, show severe neurological disorders, including mental retardation and epilepsy. Herein, we performed an immunohistochemical analysis of the number of GABAergic interneurons (GABAis), including calbindin-D28K, parvalbumin, and calretinin, in the cerebral cortex and acetylcholinergic neurons (AchNs) in the nucleus basalis of Meynert (NM) and in the pedunculopontine tegmental nucleus (PPN) in six autopsy cases of XP-A in order to investigate the relationships between mental dysfunction and GABAis and AchNs. The density and percentages of neurons that were immunoreactive for calbindin-D28K and parvalbumin were significantly reduced in the frontal and temporal cortices in XP-A cases, although the density of neurons that were immunoreactive for MAP2 did not differ from that in controls. Additionally, XP-A cases showed reduced AchNs in both the NM and the PPN. The observed reductions of cortical GABAis and AchNs may be involved in the mental disturbances, the higher occurrence of epilepsy, and/or the abnormalities in rapid eye movement sleep in patients with XP-A.

Oxidative stress in neurodegeneration in dentatorubral-pallidoluysian atrophy.

Dentatorubral-pallidoluysian atrophy (DRPLA) is one of the CAG-repeat diseases, and is classified into juvenile and early adult types showing progressive myoclonus epilepsy (PME) in addition to late adult type. We immunohistochemically examined accumulation of oxidative products and expression of superoxide dismutase (SOD) in autopsy cases of DRPLA. Oxidative products to nucleosides, 8-hydroxy-2'-deoxyguanosine and 8-hydroxyguanosine, were accumulated in the lenticulate nucleus predominantly in DRPLA cases having PME. Neuronal accumulation of 4-hydroxy nonenal, a reactive lipid aldehyde, was found in the hippocampus, globus pallidus and cerebellar dentate nucleus in adult DRPLA cases and controls. Cytoplasmic immunoreactivity for Cu/ZnSOD was reduced in the external segment of globus pallidus, dentate nucleus and cerebellar cortex in DRPLA cases. Mitochondrial immunoreactivity for MnSOD was reduced in the lenticulate nucleus and cerebellum in DRPLA cases having PME. Some DRPLA cases showed reduced immunoreactivity for MnSOD in the cerebral cortex. Coexistence of reduced SOD expression and polyglutamine was observed in a few cases. It has been discussed in Huntington's disease that expanded polyglutamine can lead to oxidative neurodegeneration. It is likely that oxidative stress can be involved in DRPLA, although relationship with expanded polyglutamine remains to be elusive.

Mechanisms of neurodegeneration in mucopolysaccharidoses II and IIIB: analysis of human brain tissue.

Mucopolysaccharidoses (MPS) are inherited disorders caused by the deficiency of lysosomal enzymes. Sanfilippo syndrome (MPS III) and Hunter syndrome (MPS II) are characterized by severe and mild neurological disorders, respectively, in which the neurodegenerative mechanisms remain to be clarified. We immunohistochemically examined the involvement of tauopathy/synucleinopathy, cell death and oxidative damage in the brains of three cases each of MPS IIIB and MPS II and age-matched controls. In cases of MPS IIIB, the density of GABAergic interneurons in the cerebral cortex immunoreactive for calbindin-D28K and parvalbumin was markedly reduced when compared with age-matched controls. The swollen neurons showed immunoreactivity for phosphorylated alpha-synuclein but not for phosphorylated tau protein or beta-amyloid protein; those in the cerebral cortex demonstrated nuclear immunoreactivity for TUNEL, single-stranded DNA and 8-OHdG. Neither lipid peroxidation nor protein glycation was marked in MPS cases. The expression levels of superoxide dismutases (Cu/ZnSOD and MnSOD) and glial glutamate transporters (EAAT1 and EAAT2) were reduced in two MPS II cases. The disturbance of GABAergic interneurons can be related to mental disturbance, while synucleinopathy and/or DNA impairment may be implicated in the neurodegeneration of swelling neurons due to storage materials in MPS IIIB cases. These findings suggest the possibility of neuroprotective therapies other than enzyme replacement in MPS patients.

Neuropathological analysis of the brainstem and cerebral cortex lesions on epileptogenesis in hereditary dentatorubral-pallidoluysian atrophy.

In order to investigate epileptogenesis in hereditary dentatorubral-pallidoluysian atrophy (DRPLA), we immunohistochemically examined the expression of neurotransmitters, neuropeptides, calcium-binding proteins and/or glutamate transporters in the brainstem and cerebral cortex in autopsy cases. The subjects comprised 14 cases of clinicopathologically confirmed DRPLA, including 7 cases of juvenile and 2 cases of early adult types with progressive myoclonus epilepsy (PME), 5 cases of late adult type without PME, and 10 age-matched controls. Serial sections of the brainstem and cerebral cortex were treated with antibodies to tyrosine hydroxylase, tryptophan hydroxylase, substance P, methionine-enkephalin, parvalbumin, calbindin-D28K, calretinin, and excitatory amino acid transporters. Although the size of the tegmentum was small, we failed to find any PME-specific brainstem changes in the expression of neurotransmitters, neuropeptides and calcium-binding proteins. The number of interneurons immunoreactive for calbindin-D28K and parvalbumin, markers of GABAergic inhibitory interneurons, were reduced throughout the cerebral cortex, but there was no significant difference in the density of immunoreactive neurons between DRPLA patients of each type. The expression of glutamate transporters was comparatively spared. The current study revealed an absence of PME-specific brainstem lesions and indicated a possible involvement of the reduced GABAergic interneurons in the cerebral cortex in formation of PME in DRPLA.

Oxidative nucleotide damage and superoxide dismutase expression in the brains of xeroderma pigmentosum group A and Cockayne syndrome.

Xeroderma pigmentosum group A (XPA) and Cockayne syndrome (CS) are caused by a genetic defect of nucleotide excision repair mechanisms, showing cutaneous hypersensitivity to sunlight and progressive neurological disturbances. The cause of neurological abnormalities has yet to be clarified and fundamental treatments have never been established in both disorders. In order to investigate neurodegeneration of XPA and CS, we immunohistochemically examined deposition of oxidative stress-related materials of nucleotides and expression of two types of superoxide dismutase (SOD) in the brains from autopsy cases of XPA and CS. Cases of XPA but not CS demonstrated nuclear deposition of 8-hydroxy-2'-deoxyguanosine and cytoplasmic deposition of 8-hydroxyguanosine, being speculated as oxidative stress-related materials of DNA and RNA, respectively, in the globus pallidus. Four of five XPA cases exhibited reduced neuronal immunoreactivity for Cu/ZnSOD in the cerebral and cerebellar corteces in addition to the basal ganglia, and two XPA cases showed reduced immunoreactivity for MnSOD in the brain regions examined. In contrast, five CS cases demonstrated comparatively preserved immunoreactivity for Cu/ZnSOD and MnSOD. Both XPA and CS cases showed increased cytoplasmic immunoreactivity for Cu/ZnSOD and/or MnSOD in the microglial cells in the cerebral and cerebellar white matters. These findings suggest that oxidative damage to nucleotides and disturbed SOD expression can be involved in neurodegeneration in XPA but not CS.

Brainstem and basal ganglia lesions in xeroderma pigmentosum group A.

Xeroderma pigmentosum group A (XPA) is a hereditary disorder characterized by cutaneous symptoms and progressive neurodegeneration. Since XPA patients exhibit peripheral neuropathy, neuronal deafness, rigidity, dysphagia, and laryngeal dystonia, it is indispensable for investigation of the neurodegeneration to analyze brainstem and basal ganglia lesions clinically and pathologically; we have previously shown the role of oxidative stress in the development of basal ganglia lesions. Here we immunohistochemically examined the expression of neurotransmitters, calcium-binding proteins, and neuropeptides in the brainstem, basal ganglia, and thalamus in 5 XPA autopsy cases. In the brainstem, immunoreactivity for tyrosine hydroxylase, tryptophan hydroxylase, and calbindin-D28K was severely reduced throughout the brainstem in all the XPA cases. Nevertheless, the expressions of parvalbumin, substance P, and methionine-enkephalin in the brainstem were comparatively preserved; the exception being reduced immunoreactivity for them in the cochlear and dorsal column nuclei in 3 cases. The large cell neurons in the putamen were preferentially reduced, the immunoreactivity for tyrosine hydroxylase reflecting the dopaminergic afferent and efferent pathways was severely affected, and the expression of 3 calcium binding proteins (i.e. parvalbumin, calbindin-D28K, and calretinin) was disturbed in various ways. The expression of substance P and methionine-enkephalin, which are involved in the efferent pathways in the basal ganglia, in the globus pallidus and substantia nigra was spared. It is speculated that the selective damage to the dopamine system in the basal ganglia and the disturbed monoaminergic expression in the brainstem could be related to clinical abnormalities such as the rigidity, laryngeal dystonia, and several neurophysiological changes. Functional analysis of autopsy brains will facilitate clarification of the pathogenesis of the neurodegeneration in XPA.