Eleanor S. Roberts

Induction of Pathogenic Sets of Genes in Macrophages and Neurons in NeuroAIDS

The etiology of the central nervous system (CNS) alterations after human immunodeficiency virus (HIV) infection, such as dementia and encephalitis, remains unknown. We have used microarray analysis in a monkey model of neuroAIDS to identify 98 genes, many previously unrecognized in lentiviral CNS pathogenesis, whose expression is significantly up-regulated in the frontal lobe of simian immunodeficiency virus-infected brains. Further, through immunohistochemical illumination, distinct classes of genes were found whose protein products localized to infiltrating macrophages, endothelial cells and resident glia, such as CD163, Glut5, and ISG15. In addition we found proteins induced in cortical neurons (ie, cyclin D3, tissue transglutaminase, alpha1-antichymotrypsin, and STAT1), which have not previously been described as participating in simian immunodeficiency virus or HIV-related CNS pathology. This molecular phenotyping in the infected brains revealed pathways promoting entry of macrophages into the brain and their subsequent detrimental effects on neurons. These data support the hypothesis that in HIV-induced CNS disease products of activated macrophages and astrocytes lead to CNS dysfunction by directly damaging neurons, as well as by induction of altered gene and protein expression profiles in neurons themselves which are deleterious to their function.

Increased dendritic MAP2 expression in the hippocampus in schizophrenia

Microtubule associated proteins (MAPs) are central to the development of normal neuronal cytoarchitecture and have been reported to be altered in schizophrenia. In 12 schizophrenic (DSM-III-R criteria) and 12 control hippocampi, we estimated the MAP2 immunoreactive dendritic length using antibodies that recognize total MAP2 (MAP2-T), and a non-phosphorylated form of MAP2 (MAP2-NP). Within the corona ammonis (CA) subregions, and the subiculum, we estimated, for each antibody, the length of the immunoreactive dendritic arborisation using a stereological length estimation technique based on Bouffons Needle principle and image analysis computer software. Controlling for the confounding effects of age and post-mortem delay, we have found an elevation in overall MAP2-NP immunoreactive dendritic length among schizophrenic subjects in the CA3 (F=5.9, p=0.03), CA2 (F=6.5, p=0.02), CA1 (F=8.3, p=0.01) and subicular (F=9.5, p=0.008) hippocampal subregions. Similar analyses of MAP2-T immunoreactive dendritic length demonstrated significant elevations in the CA1 (F=8.3, p=0.02), CA4 (F=4.9, p=0.04) and subicular (F=7.4, p=0.01) regions. The findings of this quantitative study of increased MAP2 immunoreactive dendritic arborisation in schizophrenia are most likely to reflect either an altered dendritic arborisation or a generalised increase in levels of MAP2 with the hippocampal pyramidal neurons. These findings add to the growing literature indicating the presence of synaptodendritic abnormalities in schizophrenia.

Host Response and Dysfunction in the CNS during Chronic Simian Immunodeficiency Virus Infection

CNS abnormalities can be detected during chronic human immunodeficiency virus (HIV) infection, before the development of opportunistic infections or other sequelae of immunodeficiency. However, although end-stage dementia caused by HIV has been linked to the presence of infected and activated macrophages and microglia in the brain, the nature of the changes resulting in the motor and cognitive disorders in the chronic stage is unknown. Using simian immunodeficiency virus-infected rhesus monkeys, we sought the molecular basis for CNS dysfunction. In the chronic stable stage, nearly 2 years after infection, all animals had verified CNS functional abnormalities. Both virus and infiltrating lymphocytes (CD8+ T-cells) were found in the brain. Molecular analysis revealed that the expression of several immune response genes was increased, including CCL5, which has pleiotropic effects on neurons as well as immune cells. CCL5 was significantly upregulated throughout the course of infection, and in the chronic phase was present in the infiltrating lymphocytes. We have identified an altered state of the CNS at an important stage of the viral–host interaction, likely arising to protect against the virus but in the long term leading to damaging processes.

The spatial relationship between neurons and astrocytes in HIV-associated dementia.

Specific neuronal spatial distributional patterns have previously been correlated with increasing severity of HIV-associated dementia (HAD). As astrocytes are also a putative site of neurotoxicity, we investigated the spatial relationships of astrocytes with pyramidal and interneurons in the superior frontal gyrus from 29 patients who died from acquired immunodeficiency syndrome. Frontal cortical brain tissue was taken from diseased HIV patients who had been assessed for the presence and severity of HAD using the Memorial Sloan-Kettering Scale. No correlation was found between neuronal density and severity of dementia. However, the pattern of astrocytes became more clustered as dementia progressed. Bivariate spatial pattern analysis of neuronal populations with astrocytes revealed that, with increasing dementia severity, astrocytes and large pyramidal neurons increasingly “repelled” each other, while astrocytes and interneurons evidenced increasing “attraction.” This implies that astrocytes may be more likely to be situated in the vicinity of surviving interneurons but less likely to be situated near surviving large pyramidal neurons in the setting of progressing HAD.

Psychiatry and the microscope - the application of cellular brain quantitation to characterize psychiatric disorders

This article will outline the newly developing stereological methods of quantitation. Such techniques are becoming increasingly relevant to investigations of psychiatric disorders. Sensitive and accurate methods of detecting cellular alterations are essential when studying disorders such as schizophrenia and mood disorders in which the microscopic brain changes are subtle. This review will firstly address issues of sampling the brain tissue for quantitative studies, secondly the various probes that are available for assessing cell number and size will be mentioned, and finally the principles of assessing cell spatial arrangement will be discussed. Examples of stereological studies of psychiatric disorders are included.