The aggregation state of α-synuclein deposits in dermal nerve fibers of patients with Parkinson's disease resembles that in the brain.

INTRODUCTION: Phosphorylated α-synuclein (p-α-syn) can be detected in dermal nerve fibers of patients with Parkinson's disease (PD) and multiple system atrophy (MSA). Here we investigated whether p-α-syn in the cutaneous nerve fibers represents misfolded aggregated protein. METHODS: Using immunofluorescence with conformation specific antibodies and digestion with proteinase K (PK), we studied skin biopsies from a cohort of patients with early stage PD (Hoehn and Yahr I/II, n=27), MSA with predominant parkinsonism (MSA-P, n=8) and normal controls (n=21). RESULTS: We could show that α-synuclein (α-syn) found in the dermal nerve fibers in PD and MSA-P is not only phosphorylated but represents PK resistant and truncated aggregated protein. Comparison with a post mortem midbrain sample revealed a similar staining pattern of pathologic α-syn lesions in the PD brain. CONCLUSION: Immunostaining of nerve fibers with different conformation specific antibodies and digestion with PK gave comparable results between midbrain and skin sections, showing that cutaneous nerve deposits of α-syn are structurally similar to Lewy pathology in the brain and are highly specific for synucleinopathy.

Neurochemical markers as potential indicators of postmortem tissue quality.

Premortem, postmortem, and storage conditions are parameters that can influence the quality and interpretation of data from studies of postmortem tissue. While many neurochemicals in the brain are relatively stable for several hours after death if stored at 4°C, the postmortem delay nevertheless becomes an important variable when examining the disease state because neurochemical levels may change with extended postmortem delay. Moreover, in the postmortem brain, neurochemical levels may also play a key role in determining the diagnosis. This is particularly true for some neurodegenerative disorders where many of the clinical features of the disease are not exclusive to one illness. It is therefore imperative to employ brain tissue of the highest quality from both nondiseased (control) and diseased brain tissue to ascertain the specific molecular and genetic mechanisms particular to the disease pathogenesis. Consequently, it would be very useful if specific markers could be employed to demonstrate and determine the quality of postmortem brain tissue that is suitable for such studies. In this chapter, the following neurochemical markers are critically reviewed as potential candidates to assess the quality of postmortem brain tissue: tryptophan levels, glutathione levels (and glutathione metabolic enzymes), enzymatic activities (glutamate decarboxylase, phosphofructokinase-1), epigenetic enzymes (acetyltransferase, methyltransferase), and tissue pH. In conclusion, the neurochemical tryptophan appears to be the most suitable candidate for assessing the integrity and quality of postmortem brain tissue. However, to optimize the quality of the samples, neuropathologic diagnostic characterization must also be employed in the interpretation and understanding of the data generated. It would also be judicious to consider as many premortem and postmortem conditions as possible as they can also affect the genetic and molecular integrity of the brain tissue.

Chronophin is a glial tumor modifier involved in the regulation of glioblastoma growth and invasiveness.

Glioblastoma is the most aggressive primary brain tumor in adults. Although the rapid recurrence of glioblastomas after treatment is a major clinical challenge, the relationships between tumor growth and intracerebral spread remain poorly understood. We have identified the cofilin phosphatase chronophin (gene name: pyridoxal phosphatase, PDXP) as a glial tumor modifier. Monoallelic PDXP loss was frequent in four independent human astrocytic tumor cohorts and increased with tumor grade. We found that aberrant PDXP promoter methylation can be a mechanism leading to further chronophin downregulation in glioblastomas, which correlated with shorter glioblastoma patient survival. Moreover, we observed an inverse association between chronophin protein expression and cofilin phosphorylation levels in glioma tissue samples. Chronophin-deficient glioblastoma cells showed elevated cofilin phosphorylation, an increase in polymerized actin, a higher directionality of cell migration, and elevated in vitro invasiveness. Tumor growth of chronophin-depleted glioblastoma cells xenografted into the immunodeficient mouse brain was strongly impaired. Our study suggests a mechanism whereby the genetic and epigenetic alterations of PDXP resulting in altered chronophin expression may regulate the interplay between glioma cell proliferation and invasion.

Fatal PML associated with efalizumab therapy: insights into integrin αLß2 in JC virus control.

OBJECTIVES: Progressive multifocal leukoencephalopathy (PML) has become much more common with monoclonal antibody treatment for multiple sclerosis and other immune-mediated disorders. METHODS: We report 2 patients with severe psoriasis and fatal PML treated for ≥3 years with efalizumab, a neutralizing antibody to αLß2-leukointegrin (LFA-1). In one patient, we conducted serial studies of peripheral blood and CSF including analyses of leukocyte phenotypes, migration ex vivo, and CDR3 spectratypes with controls coming from HIV-infected patients with PML. Extensive pathologic and histologic analysis was done on autopsy CNS tissue of both patients. RESULTS: Both patients developed progressive cognitive and motor deficits, and JC virus was identified in CSF. Despite treatment including plasma exchange (PE) and signs of immune reconstitution, both died of PML 2 and 6 months after disease onset. Neuropathologic examination confirmed PML. Efalizumab treatment was associated with reduced transendothelial migration by peripheral T cells in vitro. As expression levels of LFA-1 on peripheral T cells gradually rose after PE, in vitro migration increased. Peripheral and CSF T-cell spectratyping showed CD8+ T-cell clonal expansion but blunted activation, which was restored after PE. CONCLUSIONS: From these data we propose that inhibition of peripheral and intrathecal T-cell activation and suppression of CNS effector-phase migration both characterize efalizumab-associated PML. LFA-1 may be a crucial factor in homeostatic JC virus control.

pH measurement as quality control on human post mortem brain tissue: a study of the BrainNet Europe consortium.

AIMS: Most brain diseases are complex entities. Although animal models or cell culture experiments mimic some disease aspects, human post mortem brain tissue remains essential to advance our understanding of brain diseases using biochemical and molecular techniques. Post mortem artefacts must be properly understood, standardized, and either eliminated or factored into such experiments. Here we examine the influence of several premortem and post mortem factors on pH, and discuss the role of pH as a biochemical marker for brain tissue quality. METHODS: We assessed brain tissue pH in 339 samples from 116 brains provided by 8 different European and 2 Australian brain bank centres. We correlated brain pH with tissue source, post mortem delay, age, gender, freezing method, storage duration, agonal state and brain ischaemia. RESULTS: Our results revealed that only prolonged agonal state and ischaemic brain damage influenced brain tissue pH next to repeated freeze/thaw cycles. CONCLUSIONS: pH measurement in brain tissue is a good indicator of premortem events in brain tissue and it signals limitations for post mortem investigations.