How and why I fell into neuropathology.

I'm going to explain how and why I fell into the Department of Neuropathology at the Pitié-Salpêtrière Hospital of Paris. I'd also like to sketch the history of French neuropathology in the years 1960-2010, as seen by a naive young student, and then by a practicing neuropathologist (often still very naive). As a matter of fact, although the history of neurosciences [1-2] and the Pitié-Salpêtrière Hospital in Paris [3-4] have been the subject of numerous publications, the history of neuropathology in this hospital has been rarely documented [5-6]. I spent more than forty years strolling along the alleys of La Salpêtrière, among its old pavilions, the Saint Louis chapel, the "Pavillon des folles", the courtyard of Manon Lescaut and the guard room. I worked full-time between the Escourolle laboratory, the "Amphithéâtre des morts" and the University. It has been a real pleasure to be part of this world. I would also like to offer young doctors in training and future neuropathologists some advice that might help them in the choice and development of their future careers.

[Measles subacute sclerosing panencephalitis (SSPE): A still present and still mysterious fatal disease. History, Diagnosis and Assumptions]. / La panencéphalite sclérosante subaiguë de la rougeole - Une maladie mortelle encore présente et toujours mystérieuse.

Subacute sclerosing panencephalitis, a late complication of measles, is still present during epidemics of this disease due to insufficient vaccination. After a historical review, the importance of the diagnostic criteria and the pathophysiology of SSEP are discussed. Numerous studies on the parameters of innate immunity and interferon responses tend to show a decrease in the activity of cellular immunity. Several hypotheses are formulated based on the publications of the different forms of the disease: Congenital, perinatal, forms with short incubation similar to acute inclusion encephalitis (AIE), rapidly evolving forms, forms of the immunocompromised, or even adults. Familial forms have been identified, suggesting a genetic cause. Based on the duration of the latency period, two groups have been individualized, prompting a retrospective and prospective analysis of the exomes of these patients. The knowledge of the genes involved should be useful for the understanding of the pathophysiology of SSPE and other late neurological RNA virus infections.

Title: La panencéphalite sclérosante subaiguë de la rougeole - Une maladie mortelle encore présente et toujours mystérieuse. Abstract: La panencéphalite sclérosante subaiguë (PESS), une complication tardive de la rougeole, est encore présente lors d'épidémies de cette maladie dues aux insuffisances de la vaccination. Après un rappel historique, nous aborderons la physiopathologie de la PESS et l'importance des critères diagnostiques. De nombreux travaux portant sur les paramètres de l'immunité innée et sur ceux des réponses interféron tendent à montrer une baisse de l'activité de l'immunité cellulaire au cours de cette maladie. Nous formulons ici plusieurs hypothèses s'appuyant sur des publications concernant différentes formes de la maladie : congénitales, périnatales, formes à incubation courte, semblables à l'encéphalite aiguë à inclusions (EAI), formes d'évolution rapide, formes retrouvées chez les immunodéprimés ou chez l'adulte. Des formes familiales ont également été identifiées, suggérant une origine génétique. Selon la durée de la période de latence entre rougeole et la PESS, deux groupes de patients ont été individualisés, incitant à des analyses rétrospective et prospective des exomes de ces malades. La connaissance des gènes participant à la maladie devrait être utile pour la compréhension de la physiopathologie de la PESS mais aussi d'autres infections neurologiques tardives dues à des virus à ARN.

Charcot identifies and illustrates amyotrophic lateral sclerosis.

Jean-Martin Charcot described what he called amyotrophic lateral sclerosis in his 12th and 13th lessons published in 1873 by Bourneville. He distinguished the symptoms that were related to the lesion of the anterior horn of the spinal cord and those that were due to the degeneration (that he named "sclerosis") of its lateral column. He thought that "inflammation" progressed from the lateral column to the anterior horn (but the term inflammation is not to be taken in the current meaning): the lesion of the anterior horn was thus "deuteropathic". An album containing drawings made by Charcot is kept in La Salpêtrière Neuropathology Department. Four drawings are pasted on one of its pages, showing the degeneration of the pyramidal tract. They constitute the original of the engravings illustrating Charcot's 12th lesson. The illustration of the fascicular atrophy of the adductor pollicis presented in the album does not appear in the lessons, even though this alteration is widely discussed and linked to the lesion of the anterior horn, which was supposed to ensure the "nutrition" of the muscle. The technique used by Charcot and his interpretation of the microscopic pictures, as exposed in his lessons, are discussed.

Amyloid Angiopathy in Brain Hemorrhage: A Postmortem Neuropathological-Magnetic Resonance Imaging Study.

BACKGROUND: Risk factors for intracerebral hemorrhage (ICH) include hypertension and cerebral amyloid angiopathy (CAA). The objective of this study was to determine the autopsy prevalence of CAA and the potential overlap with other risk factors among patients who died from ICH and also the correlation of CAA with cerebral microbleeds. METHODS: We analyzed 81 consecutive autopsy brains from patients with ICH. Staining for CAA detection was performed. We used an age- and sex-matched control group of routine brain autopsies of nonneurological patients to determine the frequencies of CAA and hypertension. Postmortem 3D T2-weighted gradient-echo magnetic resonance imaging (MRI) with a 1.5-T magnet was performed in 11 brains with ICH (5 with CAA and 6 without) and histological correlation was performed when microbleeds were detected. RESULTS: Hypertension and CAA were found in 69.1 and 24.7% of cases respectively. Among patients with CAA, 65.0% also had hypertension. The prevalence of CAA was similar among non-hypertensive cases and controls (33.3 and 23.1%; p = 0.54), whereas a significant difference was found between hypertensive cases vs. controls (28.9% vs. 0; p = 0.01). MRI documented 48 microbleeds and all 5 brains with CAA had ≥1 microbleed, compared to 3/6 brains without CAA. Among 48 microbleeds on MRI, 45 corresponded histologically to microbleeds surrounding microvessels (23 <200 µm in diameter, 19 between 200 µm and 2 mm, 3 were hemosiderin granules). CONCLUSIONS: Both hypertension and CAA frequently coexist in patients with ICH. MRI-detected microbleeds, proven by histological analysis, were twice as common in patients with CAA as in those with hypertensive ICH.

Accuracy of diagnosis criteria in patients with suspected diagnosis of sporadic Creutzfeldt-Jakob disease and detection of 14-3-3 protein, France, 1992 to 2009.

Diagnostic criteria of Creutzfeldt-Jakob disease (CJD), a rare and fatal transmissible nervous system disease with public health implications, are determined by clinical data, electroencephalogram (EEG), detection of 14-3-3 protein in cerebrospinal fluid (CSF), brain magnetic resonance imaging and prion protein gene examination. The specificity of protein 14-3-3 has been questioned. We reviewed data from 1,572 autopsied patients collected over an 18-year period (1992-2009) and assessed whether and how 14-3-3 detection impacted the diagnosis of sporadic CJD in France, and whether this led to the misdiagnosis of treatable disorders. 14-3-3 detection was introduced into diagnostic criteria for CJD in 1998. Diagnostic accuracy decreased from 92% for the 1992-1997 period to 85% for the 1998-2009 period. This was associated with positive detections of 14-3-3 in cases with negative EEG and alternative diagnosis at autopsy. Potentially treatable diseases were found in 163 patients (10.5%). This study confirms the usefulness of the recent modification of diagnosis criteria by the addition of the results of CSF real-time quaking-induced conversion, a method based on prion seed-induced misfolding and aggregation of recombinant prion protein substrate that has proven to be a highly specific test for diagnosis of sporadic CJD.

ADAM30 Downregulates APP-Linked Defects Through Cathepsin D Activation in Alzheimer's Disease.

Although several ADAMs (A disintegrin-like and metalloproteases) have been shown to contribute to the amyloid precursor protein (APP) metabolism, the full spectrum of metalloproteases involved in this metabolism remains to be established. Transcriptomic analyses centred on metalloprotease genes unraveled a 50% decrease in ADAM30 expression that inversely correlates with amyloid load in Alzheimer's disease brains. Accordingly, in vitro down- or up-regulation of ADAM30 expression triggered an increase/decrease in Aß peptides levels whereas expression of a biologically inactive ADAM30 (ADAM30(mut)) did not affect Aß secretion. Proteomics/cell-based experiments showed that ADAM30-dependent regulation of APP metabolism required both cathepsin D (CTSD) activation and APP sorting to lysosomes. Accordingly, in Alzheimer-like transgenic mice, neuronal ADAM30 over-expression lowered Aß42 secretion in neuron primary cultures, soluble Aß42 and amyloid plaque load levels in the brain and concomitantly enhanced CTSD activity and finally rescued long term potentiation alterations. Our data thus indicate that lowering ADAM30 expression may favor Aß production, thereby contributing to Alzheimer's disease development.

Coronary and Basilar Artery Ectasia Are Associated: Results From an Autopsy Case-Control Study.

BACKGROUND AND PURPOSE: Intracranial artery dolichoectasia (IADE) and coronary artery ectasia have been associated with stroke and myocardial infarction, respectively. Only rarely have cases of coexisting IADE and coronary artery ectasia been reported. We investigated this association in a large consecutive autopsy series. METHODS: Sixteen stroke patients with IADE were identified among 381 stroke patients and were matched with 16 stroke patients without IADE. The heart and coronary arteries from all patients were examined after a prespecified protocol. RESULTS: Coronary artery ectasia was observed in 8 of the stroke patients with IADE, and in none of the stroke patients without IADE (P=0.008). The diameters of basilar and right coronary arteries were positively correlated (IADE patients, r=0.51; P=0.003 and coronary artery ectasia patients, P=0.006). CONCLUSIONS: This autopsy study examining the association of coronary artery ectasia and IADE in stroke patients suggests a common pathogenesis.

History of Prions and transmission of protein misfolding.

Since J. Cuillé and P. L. Chelle successfully transmitted scrapie between sheep by experi- mental inoculation in 1936 and D. C. Gajdusek kuru and Creutzfeldt-Jakob disease to chimpanzee in 1966 and 1968, respectively, the nature of the agents causing these " slow virus diseases " remains a mystery. In 1982, S. Prusiner called them " PRIONs " (for " PROteinaceous INfectious particles ") because they appeared lacking the nucleic acids that would classify them viruses. Although infectious or genetic mechanisms were seldom found, most of the rare human PRION diseases appeared " sporadic ". They shared many clinical and neuropathological properties with human neurodegenerative diseases (slow development, prominent nervous system involvement, amyloid deposits, paucity of immune response) the mechanism of which was not considered usually infectious. In 1991, H. Braak showed, in Alzheimer's disease brain, the low spreading of neuropathological tau associated lesions along anatomic pathways. They appear long before the clinical signs. The abnor- mally misfolded proteins characteristics of many neurodegenerative diseases are thought to aggregate after an initial seeding. This leads to their cell-cell transmission and dissemina- tion through neuronal and extra-neuronalpathways, which unexpected extent is under study. Whether the seeding is infectious or not remains debated. This new paradigm for unders- tanding their natural history and phenotypic diversity, which has already led to assess the diagnostic value of skin biopsy, should open the door to new therapeutic approach.

Cycline efficacy on the propagation of human prions in primary cultured neurons is strain-specific.

In prion diseases, a major issue in therapeutic research is the variability of the effect between strains. Stimulated by the report of an antiprion effect in a scrapie model and by ongoing international clinical trials using doxycycline, we studied the efficacy of cyclines against the propagation of human prions. First, we successfully propagated various Creutzfeldt-Jakob disease (CJD) isolates (sporadic, variant, and iatrogenic CJD) in neuronal cultures expressing the human prion protein. Then, we found that doxycycline was the most effective compound, with important variations between isolates. Isolates from sporadic CJD, the most common form of prion disease, showed the highest sensitivity.

Axonal expression of sodium channels and neuropathology of the plaques in multiple sclerosis.

AIMS: Although demyelination is an important cause of neurological deficits in multiple sclerosis (MS), recently axonal pathology and concomitant involvement of sodium channels (Nav) became a focus of major interest. Studies in experimental autoimmune encephalomyelitis (EAE) and MS have shown diffuse expression of Nav1.6 and Nav1.2 along demyelinated axons. However, the relation between this expression by the axon and its environment is not yet known. The aim of this exploratory study was to identify the neuropathological characteristics of the plaque associated with the changes of sodium channel axonal expression. METHODS: We analysed by immunohistochemistry the expression of Nav1.6 and Nav1.2 along demyelinated axons in 64 plaques from 12 MS cases. To characterize the plaques, we used Luxol fast blue staining and immunohistochemistry for myelin basic protein, microglia/macrophages, T and B cells, reactive astrocytes and axonal lesions performed on sections of formalin-fixed, paraffin-embedded tissue. RESULTS: The presence of diffuse axonal expression of Nav1.6 was equally distributed between active demyelinating and inactive not demyelinating plaques based on presence or absence of myelin laden macrophages respectively. However, presence of diffuse axonal expression of Nav1.6 was more frequent within plaques with T cells infiltrate and microglial hyperplasia. On the other hand, Nav1.2 diffuse axonal expression seemed to be independent of the neuropathological environment of the plaque. CONCLUSIONS: The cellular environment of the axon influences the differential expression of Nav channels. A better understanding of the influence of the inflammation on sodium channels mediated axonal degeneration could offer therapeutic perspectives.

Substitutions at residue 211 in the prion protein drive a switch between CJD and GSS syndrome, a new mechanism governing inherited neurodegenerative disorders.

Human prion diseases are a heterogeneous group of fatal neurodegenerative disorders, characterized by the deposition of the partially protease-resistant prion protein (PrP(res)), astrocytosis, neuronal loss and spongiform change in the brain. Among inherited forms that represent 15% of patients, different phenotypes have been described depending on the variations detected at different positions within the prion protein gene. Here, we report a new mechanism governing the phenotypic variability of inherited prion diseases. First, we observed that the substitution at residue 211 with either Gln or Asp leads to distinct disorders at the clinical, neuropathological and biochemical levels (Creutzfeldt-Jakob disease or Gerstmann-Sträussler-Scheinker syndrome with abundant amyloid plaques and tau neurofibrillar pathology). Then, using molecular dynamics simulations and biophysical characterization of mutant proteins and an in vitro model of PrP conversion, we found evidence that each substitution impacts differently the stability of PrP and its propensity to produce different protease resistant fragments that may contribute to the phenotypical switch. Thus, subtle differences in the PrP primary structure and stability are sufficient to control amyloid plaques formation and tau abnormal phosphorylation and fibrillation. This mechanism is unique among neurodegenerative disorders and is consistent with the prion hypothesis that proposes a conformational change as the key pathological event in prion disorders.

Consensus classification of human prion disease histotypes allows reliable identification of molecular subtypes: an inter-rater study among surveillance centres in Europe and USA.

The current classification of human sporadic prion diseases recognizes six major phenotypic subtypes with distinctive clinicopathological features, which largely correlate at the molecular level with the genotype at the polymorphic codon 129 (methionine, M, or valine, V) in the prion protein gene and with the size of the protease-resistant core of the abnormal prion protein, PrP(Sc) (i.e. type 1 migrating at 21 kDa and type 2 at 19 kDa). We previously demonstrated that PrP(Sc) typing by Western blotting is a reliable means of strain typing and disease classification. Limitations of this approach, however, particularly in the interlaboratory setting, are the association of PrP(Sc) types 1 or 2 with more than one clinicopathological phenotype, which precludes definitive case classification if not supported by further analysis, and the difficulty of fully recognizing cases with mixed phenotypic features. In this study, we tested the inter-rater reliability of disease classification based only on histopathological criteria. Slides from 21 cases covering the whole phenotypic spectrum of human sporadic prion diseases, and also including two cases of variant Creutzfeldt-Jakob disease (CJD), were distributed blindly to 13 assessors for classification according to given instructions. The results showed good-to-excellent agreement between assessors in the classification of cases. In particular, there was full agreement (100 %) for the two most common sporadic CJD subtypes and variant CJD, and very high concordance in general for all pure phenotypes and the most common subtype with mixed phenotypic features. The present data fully support the basis for the current classification of sporadic human prion diseases and indicate that, besides molecular PrP(Sc) typing, histopathological analysis permits reliable disease classification with high interlaboratory accuracy.

Association between a Primitive Brain Tumor and Cerebral Aspergillosis.

Cerebral aspergillosis is a rare pathology of poor prognosis in spite of the use of adapted antifungal treatments. This infection of the central nervous system is generally the complication of an invasive aspergillosis with hematogenic scattering from pulmonary focal spots. It can arise in immunocompetent patients treated with prolonged corticotherapy or chemoradiotherapy for cancer. A case of lethal cerebral aspergillosis in a patient with an infiltrative glioma treated with corticotherapy and radiotherapy is reported. Clinicopathological aspects and therapeutic approach are described.

[New insights into intracellular inclusions and intracellular proteolysis]. / Les inclusions intracellulaires sont-elles toujours des témoins d'un trouble de la protéolyse intracellulaire?

Intracellular inclusions seen by the pathologist may have variable significance. Although they are excellent markers of proteolytic disorders, they can also be due to several other mechanisms. This article examines recent data on the morphology, significance and consequences of aging lipofuscins in the brain and retina, neurofibrillary tangles and Lewy bodies, and Birbeck granules associated with Langerhans histiocytosis. Some of these disorders involve increased protein production, misfolding and aggregation, and altered intracellular proteolysis, but other cell constituents may also play a role. Proteolytic mechanisms do not appear to be involved in the formation of Birbeck granules, which helped to reveal the Langerhans origin of histiocytosis X. Analyses of intracellular inclusions, together with genetic and epigenetic studies, are highly informative in various degenerative diseases.

Fronto-temporal lobar degeneration: neuropathology in 60 cases.

Sixty cases of frontotemporal lobar degeneration (FTLD) were collected over 22 years. Brain weight was negatively correlated with disease duration. The neuronal and/or glial inclusions were labeled by anti-TDP, anti-FUS or anti-TAU antibodies, respectively, in 40, 3 and 12 cases. In the FTLD-TDP group, mutation of the progranulin gene was found in four cases (FTD-GRN), with nuclear, cat eye inclusions and severe neuronal loss in CA1 and subiculum. The motor neurons were involved in 27 cases (fronto-temporal dementia with amyotrophic lateral sclerosis = FTD-ALS). Familial FTD-ALS cases lived longer than sporadic ones. In nine cases, there was no ALS, no GRN mutation (FTD-NAP). The cases in the FTD-ALS and FTD-NAP subgroups were of Sampathu type 2 (TDP-positive inclusions located mostly in cell bodies and short neurites) with the exception of five cases which belonged to type 1 (long TDP-positive neurites in the superficial layers of the cortex). All of the FTLD-FUS of this series cases were affected by neuronal intermediate filament inclusion disease (NIFID). They were young. The survival was short. In the FTLD-tau group, mutations P301P (previously not recognized as pathogenic), P301L and S305N were identified. Pick disease (n = 5) appeared as a homogeneous sporadic disorder. The current nomenclature allows the neuropathological classification of nearly all the cases of FTD. The prevalence of the different types of FTD is tightly linked to the recruitment. This series was enriched in motor neuron disease (explaining the overall predominance of type 2 TDP inclusions).

Neuropathology of sleep disorders: a review.

Sleep disorders are important manifestations of neurodegenerativediseases and sometimes are clinically evident well before the onset of other neurological manifestations. This review addresses theneuroanatomical basis and the mechanisms of sleep regulation in humans in relation to the neuropathology of entities associated with sleep disturbances in selected diseases, including Alzheimer disease, progressive supranuclear palsy, Lewy body disorders, multiple-system atrophy, and fatal familial insomnia. This includes abnormalities of circadian rhythm, insomnia, narcolepsy, rapid eye movements sleep behavior disorders, and excessive daytime sleepiness.

Nodes of ranvier and paranodes in chronic acquired neuropathies.

Chronic acquired neuropathies of unknown origin are classified as chronic inflammatory demyelinating polyneuropathies (CIDP) and chronic idiopathic axonal polyneuropathies (CIAP). The diagnosis can be very difficult, although it has important therapeutic implications since CIDP can be improved by immunomodulating treatment. The aim of this study was to examine the possible abnormalities of nodal and paranodal regions in these two types of neuropathies. Longitudinal sections of superficial peroneal nerves were obtained from biopsy material from 12 patients with CIDP and 10 patients with CIAP and studied by immunofluorescence and in some cases electron microscopy. Electron microscopy revealed multiple alterations in the nodal and paranodal regions which predominated in Schwann cells in CIDP and in axons in CIAP. In CIDP paranodin/Caspr immunofluorescence was more widespread than in control nerves, extending along the axon in internodes where it appeared intense. Nodal channels Nav and KCNQ2 were less altered but were also detected in the internodes. In CIAP paranodes, paranodin labeling was irregular and/or decreased. To test the consequences of acquired primary Schwann cells alteration on axonal proteins, we used a mouse model based on induced deletion of the transcription factor Krox-20 gene. In the demyelinated sciatic nerves of these mice we observed alterations similar to those found in CIDP by immunofluorescence, and immunoblotting demonstrated increased levels of paranodin. Finally we examined whether the alterations in paranodin immunoreactivity could have a diagnosis value. In a sample of 16 biopsies, the study of paranodin immunofluorescence by blind evaluators led to correct diagnosis in 70 ± 4% of the cases. This study characterizes for the first time the abnormalities of nodes of Ranvier in CIAP and CIDP, and the altered expression and distribution of nodal and paranodal proteins. Marked differences were observed between CIDP and CIAP and the alterations in paranodin immunofluorescence may be an interesting tool for their differential diagnosis.

Tau-positive grains are constant in centenarians' hippocampus.

The influence of age on the prevalence of argyrophilic grain disease has been analyzed in the hippocampus from 29 centenarians. Argyrophilic grains were detected in 12 cases with Gallyas silver method, in 24 cases with anti-exon 10 (RD4) immunohistochemistry, in all the cases with a phospho-independent anti-tau (piTau) antibody and with a monoclonal antibody against Ser202 of the tau protein (AT8), suggesting a maturation of the grains. Ballooned neurons were found in the hippocampus of 12 cases in which grains were, on average, more abundant. Coiled bodies were found in 26, 15 and 13 cases respectively with piTau antibody, RD4 and Gallyas method. Cases with coiled bodies had a higher density of grains. The mean density of grains did not differ in the patients with or without dementia. The prevalence of tau-positive grains has been underestimated in the very old population. As neurofibrillary tangles, they appear to be a constant accompaniment of age but, contrarily to neurofibrillary tangles, do not seem to be strongly associated with dementia.