Impaired expression of GABA transporters in the human Alzheimer's disease hippocampus, subiculum, entorhinal cortex and superior temporal gyrus.

Gamma-aminobutyric acid (GABA) is the main inhibitory neurotransmitter in the brain and plays an important role in regulating neuronal excitability. GABA reuptake from the synapse is dependent on specific transporters - mainly GAT-1, GAT-3 and BGT-1 (GATs). This study is the first to show alterations in the expression of the GATs in the Alzheimer's disease (AD) hippocampus, entorhinal cortex and superior temporal gyrus. We found a significant increase in BGT-1 expression associated with AD in all layers of the dentate gyrus, in the stratum oriens of the CA2 and CA3 and the superior temporal gyrus. In AD there was a significant decrease in GAT-1 expression in the entorhinal cortex and superior temporal gyrus. We also found a significant decrease in GAT-3 immunoreactivity in the stratum pyramidale of the CA1 and CA3, the subiculum and entorhinal cortex. These observations indicate that the expression of the GATs shows brain-region- and layer-specific alterations in AD, suggesting a complex activation pattern of different GATs during the course of the disease.

C9ORF72 and UBQLN2 mutations are causes of amyotrophic lateral sclerosis in New Zealand: a genetic and pathologic study using banked human brain tissue.

Amyotrophic lateral sclerosis (ALS) is a devastating neurodegenerative disease, which causes progressive and eventually fatal loss of motor function. Here, we describe genetic and pathologic characterization of brain tissue banked from 19 ALS patients over nearly 20 years at the Department of Anatomy and the Centre for Brain Research, University of Auckland, New Zealand. We screened for mutations in SOD1, TARDBP, FUS, and C9ORF72 genes and for neuropathology caused by phosphorylated TDP-43, dipeptide repeats (DPRs), and ubiquilin. We identified 2 cases with C9ORF72 repeat expansions. Both harbored phosphorylated TDP-43 and DPR inclusions. We show that DPR inclusions can incorporate or occur independently of ubiquilin. We also identified 1 case with a UBQLN2 mutation, which showed phosphorylated TDP-43 and characteristic ubiquilin protein inclusions. This is the first study of ALS genetics in New Zealand, adding New Zealand to the growing list of countries in which C9ORF72 repeat expansion and UBQLN2 mutations are detected in ALS cases.

Symptom heterogeneity in Huntington's disease correlates with neuronal degeneration in the cerebral cortex.

BACKGROUND: Huntington's disease (HD) is characterised by variable symptoms and neuropathology of the basal ganglia and cortex. Previously, we have shown that the pattern of pyramidal cell loss in 8 different cortical regions correlates with the phenotypic variability in HD. In the primary motor and anterior cingulate cortices, the pattern of interneuron degeneration correlates with pyramidal cell death and variable HD symptom profiles. OBJECTIVES: This study aimed to examine the pattern of interneuron degeneration in 3 further regions of the HD cortex (primary sensory, superior frontal, superior parietal cortices) to determine whether HD neuropathogenesis was characterised by a general fundamental pattern of cortical interneuron loss, and explore the relationship between cortical interneuron loss with previously determined pyramidal cell loss and clinical heterogeneity. METHODS: Stereological counting was used to quantify 3 sub-populations of calcium-binding protein containing interneurons in 3 cortical human brain regions of 14 HD and 13 control cases as used in our previous studies (Nana et al., 2014; Kim et al., 2014). The HD cases were grouped according to their predominant symptom profile ("motor", "mood", "mixed"). RESULTS: The present results demonstrated a heterogeneous loss of interneurons across the 3 cortical regions which, when compared with our previous studies, mirrored the pattern of pyramidal cell loss in the same cortical areas. Most interestingly, the pattern of neuronal loss in these regions correlated with the variable HD symptom profiles. CONCLUSION: The overall findings in our present and previous cortical studies establish a clear correlative pattern of variable cortical neuronal degeneration in HD pathogenesis, which mirrors the heterogeneity of HD symptom phenotypes.

Globus pallidus degeneration and clinicopathological features of Huntington disease.

OBJECTIVE: Numerous studies have focused on striatal neurodegeneration in Huntington disease (HD). In comparison, the globus pallidus (GP), a main striatal output nucleus, has received less focus in HD research. This study characterizes the pattern of neurodegeneration in 3 subdivisions of the human GP, and its relation to clinical symptomatology. METHODS: Stereology was used to measure regional atrophy, neuronal loss, and soma neuronal atrophy in 3 components of the GP-the external segment (GPe), internal segment (GPi), and ventral pallidum (VP)-in 8 HD cases compared with 7 matched control cases. The findings in the HD patients were compared with HD striatal neuropathological grade, and symptom scores of motor impairment, chorea, cognition, and mood. RESULTS: Relative to controls, in the HD patients the GPe showed a 54% overall volume decline, 60% neuron loss, and 34% reduced soma volume. Similarly, the VP was reduced in volume by 31%, with 48% neuron loss and 64% reduced soma volume. In contrast, the GPi was less affected, with a 38% reduction in overall volume only. The extent of GP neurodegeneration correlated with increasing striatal neuropathological grade. Decreasing GPe and VP volumes were associated with poorer cognition and increasing motor impairments, but not chorea. In contrast, decreasing GPi volumes were associated with decreasing levels of irritability. INTERPRETATION: The HD gene mutation produces variable degrees of GP segment degeneration, highlighting the differential vulnerability of striato-GP target projections. The relationship established between clinical symptom scores and pallidal degeneration provides a novel contribution to understanding the clinicopathological associations in HD. Ann Neurol 2016;80:185-201.

Elevation of brain glucose and polyol-pathway intermediates with accompanying brain-copper deficiency in patients with Alzheimer's disease: metabolic basis for dementia.

Impairment of brain-glucose uptake and brain-copper regulation occurs in Alzheimer's disease (AD). Here we sought to further elucidate the processes that cause neurodegeneration in AD by measuring levels of metabolites and metals in brain regions that undergo different degrees of damage. We employed mass spectrometry (MS) to measure metabolites and metals in seven post-mortem brain regions of nine AD patients and nine controls, and plasma-glucose and plasma-copper levels in an ante-mortem case-control study. Glucose, sorbitol and fructose were markedly elevated in all AD brain regions, whereas copper was correspondingly deficient throughout (all P < 0.0001). In the ante-mortem case-control study, by contrast, plasma-glucose and plasma-copper levels did not differ between patients and controls. There were pervasive defects in regulation of glucose and copper in AD brain but no evidence for corresponding systemic abnormalities in plasma. Elevation of brain glucose and deficient brain copper potentially contribute to the pathogenesis of neurodegeneration in AD.

String Vessel Formation is Increased in the Brain of Parkinson Disease.

BACKGROUND: String vessels are collapsed basement membrane without endothelium and have no function in circulation. String vessel formation contributes to vascular degeneration in Alzheimer disease. By comparing to age-matched control cases we have recently reported endothelial degeneration in brain capillaries of human Parkinson disease (PD). OBJECTIVE: Current study evaluated changes of basement membrane of capillaries, string vessel formation and their association with astrocytes, blood-brain-barrier integrity and neuronal degeneration in PD. METHODS: Brain tissue from human cases of PD and age-matched controls was used. Immunohistochemical staining for collagen IV, GFAP, NeuN, tyrosine hydroxylase, fibrinogen and Factor VIII was evaluated by image analysis in the substantia nigra, caudate nucleus and middle frontal gyrus. RESULTS: While the basement-membrane-associated vessel density was similar between the two groups, the density of string vessels was significantly increased in the PD cases, particularly in the substantia nigra. Neuronal degeneration was found in all brain regions. Astrocytes and fibrinogen were increased in the caudate nuclei of PD cases compared with control cases. CONCLUSIONS: Endothelial degeneration and preservation of basement membrane result in an increase of string vessel formation in PD. The data may suggest a possible role for cerebral hypoperfusion in the neuronal degeneration characteristic of PD, which needs further investigation. Elevated astrocytosis in the caudate nucleus of PD cases could be associated with disruption of the blood-brain barrier in this brain region.

Widespread heterogeneous neuronal loss across the cerebral cortex in Huntington's disease.

Huntington's disease is an autosomal dominant neurodegenerative disease characterized by neuronal degeneration in the basal ganglia and cerebral cortex, and a variable symptom profile. Although progressive striatal degeneration is known to occur and is related to symptom profile, little is known about the cellular basis of symptom heterogeneity across the entire cerebral cortex. To investigate this, we have undertaken a double blind study using unbiased stereological cell counting techniques to determine the pattern of cell loss in six representative cortical regions from the frontal, parietal, temporal, and occipital lobes in the brains of 14 Huntington's disease cases and 15 controls. The results clearly demonstrate a widespread loss of total neurons and pyramidal cells across all cortical regions studied, except for the primary visual cortex. Importantly, the results show that cell loss is remarkably variable both within and between Huntington's disease cases. The results also show that neuronal loss in the primary sensory and secondary visual cortices relate to Huntington's disease motor symptom profiles, and neuronal loss across the associational cortices in the frontal, parietal and temporal lobes is related to both Huntington's disease motor and to mood symptom profiles. This finding considerably extends a previous study (Thu et al., Brain, 2010; 133:1094-1110) which showed that neuronal loss in the primary motor cortex was related specifically to the motor symptom profiles while neuronal loss in the anterior cingulate cortex was related specifically to mood symptom profiles. The extent of cortical cell loss in the current study was generally related to the striatal neuropathological grade, but not to CAG repeat length on the HTT gene. Overall our findings show that Huntington's disease is characterized by a heterogeneous pattern of neuronal cell loss across the entire cerebrum which varies with symptom profile.

Cortical interneuron loss and symptom heterogeneity in Huntington disease.

OBJECTIVE: The cellular basis of variable symptoms in Huntington disease (HD) is unclear. One important possibility is that degeneration of the interneurons in the cerebral cortex, which play a critical role in modulating cortical output to the basal ganglia, might play a significant role in the development of variable symptomatology in HD. This study aimed to examine whether symptom variability in HD is specifically associated with variable degeneration of cortical interneurons. METHODS: We undertook a double-blind study using stereological cell counting methods to quantify the 3 major types of γ-aminobutyric acidergic interneurons (calbindin-D28k, calretinin, parvalbumin) in 13 HD cases of variable motor/mood symptomatology and 15 matched control cases in the primary motor and anterior cingulate cortices. RESULTS: In the primary motor cortex, there was a significant loss (57% reduction) of only calbindin interneurons (p=0.022) in HD cases dominated by motor symptoms, but no significant interneuron loss in cases with a dominant mood phenotype. In contrast, the anterior cingulate cortex showed a major significant loss in all 3 interneuron populations, with 71% loss of calbindin (p=0.001), 60% loss of calretinin (p=0.001), and 80% loss of parvalbumin interneurons (p=0.005) in HD cases with major mood disorder, and no interneuron loss was observed in cases with major motor dysfunction. INTERPRETATION: These findings suggest that region-specific degeneration of cortical interneurons is a key component in understanding the neural basis of symptom heterogeneity in HD.

Cerebral amyloid angiopathy related inflammation: three case reports and a review.

Cerebral amyloid angiopathy related inflammation (CAA-I), previously described under various names, is a treatable encephalopathy usually occurring in older adults. Here, three patients are described with histopathologically confirmed CAA-I, and summarised data from the published literature are presented. CAA-I has a characteristic combination of clinical and radiological features. Definite diagnosis requires brain and leptomeningeal biopsy. A favourable response to immunosuppressive therapy is common and treatment without brain biopsy may be considered in selected patients. Diagnostic criteria for CAA-I are proposed.

Cell loss in the motor and cingulate cortex correlates with symptomatology in Huntington's disease.

Huntington's disease is an autosomal dominant inherited neurodegenerative disease with motor symptoms that are variably co-expressed with mood and cognitive symptoms, and in which variable neuronal degeneration is also observed in the basal ganglia and the cerebral cortex. We have recently shown that the variable symptomatology in Huntington's disease correlates with the variable compartmental pattern of GABAA receptor and cell loss in the striatum. To determine whether the phenotypic variability in Huntington's disease is also related to variable neuronal degeneration in the cerebral cortex, we undertook a double-blind study using unbiased stereological cell counting methods to determine the pattern of cell loss in the primary motor and anterior cingulate cortices in the brains of 12 cases of Huntington's disease and 15 controls, and collected detailed data on the clinical symptomatology of the patients with Huntington's disease from family members and clinical records. The results showed a significant association between: (i) pronounced motor dysfunction and cell loss in the primary motor cortex; and (ii) major mood symptomatology and cell loss in the anterior cingulate cortex. This association held for both total neuronal loss (neuronal N staining) and pyramidal cell loss (SMI32 staining), and also correlated with marked dystrophic changes in the remaining cortical neurons. There was also an association between cortical cell loss and striatal neuropathological grade, but no significant association with CAG repeat length in the Huntington's disease gene. These findings suggest that the heterogeneity in clinical symptomatology that characterizes Huntington's disease is associated with variation in the extent of cell loss in the corresponding functional regions of the cerebral cortex whereby motor dysfunction correlates with primary motor cortex cell loss and mood symptomatology is associated with cell loss in the cingulate cortex.

Striosomes and mood dysfunction in Huntington's disease.

Variable phenotype is common in neurological disorders with single-gene inheritance patterns. In Huntington's disease, mood and cognitive symptoms are variably co-expressed with motor symptoms. There is also variable degeneration of neurons in the two major neurochemical compartments of the striatum, the striosomes and the extrastriosomal matrix. To determine whether the phenotypic variability in Huntington's disease is related to this compartmental organization, we carried out a double-blind study in which we used GABA(A) receptor immunohistochemistry to analyse the status of striosomes and matrix in the brains of 35 Huntington's disease cases and 13 control cases, and collected detailed data on the clinical symptomatology expressed by the patients from family members and records. We report here a significant association between pronounced mood dysfunction in Huntington's disease patients and differential loss of the GABA(A) receptor marker in striosomes of the striatum. This association held for both clinical onset and end-stage assessments of symptoms. The cases with accentuated striosome abnormality further exhibited later onset age, lower disease grade and lower CAG repeat length in the HD gene. We found no independent association, however, between CAG repeat length or age of onset and mood dysfunction. We suggest that variation in clinical symptomatology in Huntington's disease is associated with variation in the relative abnormality of GABA(A) receptor expression in the striosome and matrix compartments of the striatum, and that striosome-related circuits may modulate mood functioning.

Regional and cellular gene expression changes in human Huntington's disease brain.

Huntington's disease (HD) pathology is well understood at a histological level but a comprehensive molecular analysis of the effect of the disease in the human brain has not previously been available. To elucidate the molecular phenotype of HD on a genome-wide scale, we compared mRNA profiles from 44 human HD brains with those from 36 unaffected controls using microarray analysis. Four brain regions were analyzed: caudate nucleus, cerebellum, prefrontal association cortex [Brodmann's area 9 (BA9)] and motor cortex [Brodmann's area 4 (BA4)]. The greatest number and magnitude of differentially expressed mRNAs were detected in the caudate nucleus, followed by motor cortex, then cerebellum. Thus, the molecular phenotype of HD generally parallels established neuropathology. Surprisingly, no mRNA changes were detected in prefrontal association cortex, thereby revealing subtleties of pathology not previously disclosed by histological methods. To establish that the observed changes were not simply the result of cell loss, we examined mRNA levels in laser-capture microdissected neurons from Grade 1 HD caudate compared to control. These analyses confirmed changes in expression seen in tissue homogenates; we thus conclude that mRNA changes are not attributable to cell loss alone. These data from bona fide HD brains comprise an important reference for hypotheses related to HD and other neurodegenerative diseases.

A histochemical and immunohistochemical analysis of the subependymal layer in the normal and Huntington's disease brain.

Previous studies in the rodent brain have characterised the cell types present in the subependymal layer, however the general organisation and cellular morphology of the adult human subependymal layer has not been demonstrated previously. In this study, we have demonstrated that the normal human brain subependymal layer contains three morphologically distinct types of cells, A, B and C type cells. The type A cells resembling migrating neuroblasts were located in the superficial part of the subependymal layer, type B cells resembling glial cells were evenly distributed throughout the subependymal layer and caudate nucleus, and type C cells that resembled progenitor cells were located in the deeper regions of the subependymal layer close to the caudate nucleus. We also examined the subependymal layer in the Huntington's disease brain to determine whether neurodegenerative pathology of the caudate nucleus (adjacent to the subependymal layer) altered the cellular composition of the subependymal layer. In the Huntington's disease subependymal layer there was a significant increase in the thickness of the subependymal layer compared with the normal subependymal layer (p < 0.01) and there was a 2.8-fold increase in the number of cells present in the Huntington's disease subependymal layer compared with the normal subependymal layer but the density of cells remained unchanged. As the grade of Huntington's disease increased, so did the overall number of cells in the subependymal layer. An increase in the number of type B cells was responsible for most of the increase demonstrated, however there was also an increase in the numbers of type A and C cells. To further characterise the human normal and Huntington's disease subependymal layer we used immunohistochemistry and antibodies against a range of projection neuron markers, interneuron markers, glial cell markers and GABAA receptor subunits. The results demonstrated the presence of increased numbers of neuropeptide Y positive cells in the Huntington's disease subependymal layer compared with the normal subependymal layer, suggesting that neuropeptide Y neurons may play a role in progenitor cell proliferation. Also there was an increased level of the developmentally active GABAA receptor subunit gamma 2 that indicates that the adult subependymal layer still retains the ability to proliferate. Taken together our results give a detailed description of the adult human subependymal layer and also demonstrate the plasticity of the human subependymal layer in response to Huntington's disease.