The brain immune response in human prion diseases. Microglial activation and microglial disease. I. Sporadic Creutzfeldt-Jakob disease.

A study of microglial activation and its contribution to the CNS immune response was performed on the brain autopsy material of 40 patients with definite sporadic Creutzfeldt-Jakob disease (sCJD). Spatial patterns of microglial activation and prion protein disease-associated (PrPd) deposition were compared in cerebellar and cerebral cortices using immunohistochemical (IHC) activation markers. Morphological phenotype forms of microglial cells in activation stages were assessed immunohistochemically (IHC). The immune inflammatory response dominated by microglia was found to be a characteristic feature in CJD. Differences in the intensity and patterns of microglial activation corresponded to variable patterns of PrP deposition, whereas the morphological phenotype forms of microglia were specific for activation stages. The presence of activated microglial cells in the various activation stages regardless of illness duration indicates continuous microglial activity and microglial contribution to the spread of infection for the whole symptomatic period of the disease. Remarkable vacuolar degeneration changes of numerous microglial cells in different activation stages including homing stage may suggest dysfunction of microglial immune surveillance in human sCJD that can significantly contribute to transmissible spongiform encephalopathy (TSE) pathogenesis.

Limbic neuropathology in idiopathic Parkinson's disease with concomitant dementia.

To study pathological background of dementia in idiopathic Parkinson's disease (PD), 41 autopsy brains (31 cases with and 10 cases without dementia) were investigated. The severity of degenerative changes was evaluated in selected limbic regions (trans- and entorhinal cortex, hippocampus, and amygdala). The densities of Lewy bodies (LBs), Lewy neurites (LNs), neurofibrillary tangles (NFTs), and amyloid neuritic plaques (NPs) were determined on immunohistochemically stained sections using antibodies against alpha-synuclein, tau-protein, and amyloid-beta. Precisely defined modern criteria for selecting study cohort (Newcastle, CERAD and Braak et al.) ensured homogeneity of the study sample and reliability of the results. Comparisons between the cases of Parkinson's disease with dementia (PDD) and those without (PD-only) revealed that the former were characterised by significantly higher densities of LBs and LNs in transentorhinal and entorhinal cortices as well as in the CA2-3 region of the hippocampus and cortical complex of amygdala. In the PDD sub-set we found statistically significant correlation of LBs with LNs counts in CA2-3 region of hippocampus as well as of LBs counts in transentorhinal cortex with LNs counts in CA2-3 hippocampal region. The relationship was also observed between LBs counts in CA2-3 region of the hippocampus and LNs counts in cortical complex of amygdala. Our studies suggest that dementia in PD may be associated with the presence of degenerative changes of PD-type in leading limbic structures, without co-existent Alzheimer's disease (AD). They also imply that LBs and LNs may appear to be morphological hallmarks of the pathological process associated with dementia in PD. LBs and LNs distribution pattern and correlations of LBs with LNs counts in limbic regions observed in our study suggest the cumulative patomechanism of changes dependent on transsynaptic alpha-syn pathology and indicate the spread of the pathological process via axonal transport. The coexistence of the small number of changes of AD-type may exacerbate cognitive deficits in PDD.

Degenerative axonal changes in the hippocampus and amygdala in Parkinson's disease.

The morphological background of cognitive and emotional impairments in Parkinson's disease (PD) has not yet been fully explained. We evaluated the expression of synaptic proteins: alpha- and beta-synuclein, synaptophysin and synaptobrevin and ultrastructural changes of perikaryons and axons in limbic structures at post-mortem from cases of PD to estimate degenerative axonal pathology in the hippocampus and amygdala [corrected]. Limbic structures (enthorinal cortex, hippocampus, and amygdala) are essential for the cognitive processes and emotional behaviour. We found that presynaptic axon pathology is mostly connected with hippocampal CA2-3 and dentate hilar regions as well as with the cortical and medio-central complexes of amygdala. Heterogeneous immunoreactivity of alpha-synuclein and diversified ultrastructure of Lewy bodies (LBs) and Lewy neurites (LNs) indicate their consecutive developmental stages. We observed an excessive perineuroneal expression of synaptophysin in the dentate hilar region in all PD cases, except one. This suggests that the dysfunction of synapses in this region may result from axonal pathology. Our study indicates a relation between cognitive and behavioural symptomatology in PD and alpha-synuclein dependent axonal pathology in the hippocampus and amygdala.

Suspensional reaggregates of human foetal neocortex and tegmentum as objects of neurotransplantation.

Suspensional reaggregates were obtained from human neocortical and tegmental anlagen (7 weeks of gestation), using 0.1% tripsin solution, and cultivated in Medium 199. Suspensional reaggregates, formed after 2 days in vitro, were grafted into the Wistar rat striatum. Incipient stages of histogenesis in the reaggregates and their interaction with host brain were investigated using light and electron microscopy, with antibodies against vimentin, glial fibrillary acidic protein (GFAP), proliferating cell nuclear antigen (PCNA), ferritin, as well as lectin ricinus communis agglutinin (RCA). The reaggregates showed a low level of tissue organisation. An intermediate condition between suspension and the true tissue could be observed in them. These reaggregates had two evident features: a rather irregular cell arrangement (without parallel bundles of radial glia), and the presence of special intercellular junctions. Some cells made up fragments of neuroepithelial sheet in the form of true rosettes. The one-week-old grafts were integrated with the host brain as well as dissociated and contained host astrocytes. Degenerated cells and detritus appeared rarely. The data of this work let us conclude that the suspensional aggregate grafting combines some advantages of suspensional and solid grafting methods.