Infections of the central nervous system: Neuropathology.

Encephalitides include a large variety of diseases with high morbidity and mortality. Although the majority of identified pathogens are viruses, the cause of the disease remains unexplained in more than half of the cases despite extensive testing. Neuropathology provides the bases of our understanding of the inflammatory lesions in the central nervous system. Brain biopsy proves to be necessary in cases of unknown etiology, which deteriorate despite treatment. Unexpected pathogens can be uncovered by untargeted transcriptomic analysis, based on deep sequencing of small quantities of pathological brain tissue. Combined with immunohistochemistry and in situ hybridization, using tailored antibodies and probes, this next generation sequencing method opens perspectives in the diagnosis of encephalitides with a high efficiency particularly in, but not limited to, immunocompromised patients.

Next-Generation Sequencing for Diagnosis and Tailored Therapy: A Case Report of Astrovirus-Associated Progressive Encephalitis.

A boy with X-linked agammaglobulinemia experienced progressive global motor decline, cerebellar syndrome, and epilepsy. All standard polymerase chain reactions for neurotropic viruses were negative on cerebrospinal fluid and brain biopsy. Next-generation sequencing allowed fast identification of a new astrovirus strain (HAstV-VA1/HMO-C-PA), which led to tailor the patient's treatment, with encouraging clinical monitoring over 1 year.

Frontotemporal lobar degeneration: diversity of FTLD lesions.

Frontotemporal lobar degeneration (FTLD) is a heterogeneous group including both sporadic and familial diseases, characterized by a macroscopic alteration. It may correspond to various cognitive syndromes: behavioral variant of frontotemporal dementia (bvFTD), progressive nonfluent aphasia, and semantic dementia. The neuropathologic classification is now based on identification of the protein that accumulates in neurons and glia: Tau, TAR DNA Binding Protein 43 (TDP-43), and FUsed in Sarcoma (FUS). The disorders in which the corresponding proteins accumulate have been named FTLD-Tau, FTLD-TDP, and FTLD-FUS. FTLD-Tau includes sporadic cases (e.g. Pick's disease) and Tau mutations. FTLD-TDP are subdivided within four types (A, B, C, D) according to the shape and distribution of TDP-43 positive lesions within the associative frontal cortex. The FTLD-FUS group includes atypical FTLD with ubiquitinated lesions (FTLD-U), Neuronal Intermediate Filament Inclusion Disease (NIFID) and Basophilic Inclusion Body Disease (BIBD).

SOX17 is expressed in regenerating oligodendrocytes in experimental models of demyelination and in multiple sclerosis.

We have previously demonstrated that Sox17 expression is prominent at developmental stages corresponding to oligodendrocyte progenitor cell (OPC) cycle exit and onset of differentiation, and that Sox17 promotes initiation of OPC differentiation. In this study, we examined Sox17 expression and regulation under pathological conditions, particularly in two animal models of demyelination/remyelination and in post-mortem multiple sclerosis (MS) brain lesions. We found that the number of Sox17 expressing cells was significantly increased in lysolecithin (LPC)-induced lesions of the mouse spinal cord between 7 and 30 days post-injection, as compared with controls. Sox17 immunoreactivity was predominantly detected in Olig2(+) and CC1(+) oligodendrocytes and rarely in NG2(+) OPCs. The highest density of Sox17(+) oligodendrocytes was observed at 2 weeks after LPC injection, coinciding with OPC differentiation. Consistent with these findings, in cuprizone-treated mice, Sox17 expression was highest in newly generated and in maturing CC1(+) oligodendrocytes, but low in NG2(+) OPCs during the demyelination and remyelination phases. In MS tissue, Sox17 was primarily detected in actively demyelinating lesions and periplaque white matter. Sox17 immunoreactivity was co-localized with NOGO-A+ post-mitotic oligodendrocytes both in active MS lesions and periplaque white matter. Taken together, our data: (i) demonstrate that Sox17 expression is highest in newly generated oligodendrocytes under pathological conditions and could be used as a marker of oligodendrocyte regeneration, and (ii) are suggestive of Sox17 playing a critical role in oligodendrocyte differentiation and lesion repair.

Elevated levels of IFNγ and LIGHT in the spinal cord of patients with sporadic amyotrophic lateral sclerosis.

BACKGROUND: Amyotrophic lateral sclerosis (ALS) is a paralytic and fatal neurodegenerative disorder caused by the gradual loss of both upper and lower motoneurons. There is compelling evidence from ALS experimental models that neuroinflammation actively contributes to motoneuron damage. We recently proposed that interferon gamma (IFNγ), a potent proinflammatory cytokine, induces motoneuron death by eliciting the activation of the lymphotoxin beta receptor (LT-ßR) through its ligand LIGHT. Here, we explore the pertinence of this non-cell-autonomous mechanism in human ALS. METHODS: The levels and expression pattern of IFNγ, LIGHT, and LT-ßR were investigated by Western blot and immunohistochemical analysis in spinal cord of patients with sporadic ALS. RESULTS: We observed significant increased levels of IFNγ in human ALS spinal cords compared to control cases. We found that large ventral horn neurons as well as glial cells were immunoreactive for IFNγ in sporadic ALS spinal cord. We further observed that LIGHT and LT-ßR were expressed mainly by motoneurons in both ALS and control cases, and while LT-ßR levels remained constant between ALS and control cases, LIGHT levels were increased in human ALS spinal cords. CONCLUSION: These findings in sporadic ALS cases, which are consistent with the observation made in ALS experimental models, propose that the IFNγ-triggered LIGHT/LT-ßR-mediated death pathway may contribute to human ALS pathogenesis.

IFNγ triggers a LIGHT-dependent selective death of motoneurons contributing to the non-cell-autonomous effects of mutant SOD1.

Amyotrophic lateral sclerosis (ALS) is an incurable neurodegenerative disease that primarily affects motoneurons in the brain and spinal cord. Dominant mutations in superoxide dismutase-1 (SOD1) cause a familial form of ALS. Mutant SOD1-damaged glial cells contribute to ALS pathogenesis by releasing neurotoxic factors, but the mechanistic basis of the motoneuron-specific elimination is poorly understood. Here, we describe a motoneuron-selective death pathway triggered by activation of lymphotoxin-ß receptor (LT-ßR) by LIGHT, and operating by a novel signaling scheme. We show that astrocytes expressing mutant SOD1 mediate the selective death of motoneurons through the proinflammatory cytokine interferon-γ (IFNγ), which activates the LIGHT-LT-ßR death pathway. The expression of LIGHT and LT-ßR by motoneurons in vivo correlates with the preferential expression of IFNγ by motoneurons and astrocytes at disease onset and symptomatic stage in ALS mice. Importantly, the genetic ablation of Light in an ALS mouse model retards progression, but not onset, of the disease and increases lifespan. We propose that IFNγ contributes to a cross-talk between motoneurons and astrocytes causing the selective loss of some motoneurons following activation of the LIGHT-induced death pathway.

MR-guided transcranial brain HIFU in small animal models.

Recent studies have demonstrated the feasibility of transcranial high-intensity focused ultrasound (HIFU) therapy in the brain using adaptive focusing techniques. However, the complexity of the procedures imposes provision of accurate targeting, monitoring and control of this emerging therapeutic modality in order to ensure the safety of the treatment and avoid potential damaging effects of ultrasound on healthy tissues. For these purposes, a complete workflow and setup for HIFU treatment under magnetic resonance (MR) guidance is proposed and implemented in rats. For the first time, tissue displacements induced by the acoustic radiation force are detected in vivo in brain tissues and measured quantitatively using motion-sensitive MR sequences. Such a valuable target control prior to treatment assesses the quality of the focusing pattern in situ and enables us to estimate the acoustic intensity at focus. This MR-acoustic radiation force imaging is then correlated with conventional MR-thermometry sequences which are used to follow the temperature changes during the HIFU therapeutic session. Last, pre- and post-treatment magnetic resonance elastography (MRE) datasets are acquired and evaluated as a new potential way to non-invasively control the stiffness changes due to the presence of thermal necrosis. As a proof of concept, MR-guided HIFU is performed in vitro in turkey breast samples and in vivo in transcranial rat brain experiments. The experiments are conducted using a dedicated MR-compatible HIFU setup in a high-field MRI scanner (7 T). Results obtained on rats confirmed that both the MR localization of the US focal point and the pre- and post-HIFU measurement of the tissue stiffness, together with temperature control during HIFU are feasible and valuable techniques for efficient monitoring of HIFU in the brain. Brain elasticity appears to be more sensitive to the presence of oedema than to tissue necrosis.

Chromosome 9p-linked families with frontotemporal dementia associated with motor neuron disease.

BACKGROUND: Frontotemporal dementia associated with motor neuron disease (FTD-MND) is a rare neurodegenerative disorder that may be inherited by autosomal dominant trait. No major gene has been identified but a locus was mapped on chromosome 9 (9p21.3-p13.3). METHODS: Ten French families with FTD-MND were tested for linkage to the 9p21.3-p13.3 region. We report extensive mutation screening in 9p-linked families and their clinical characteristics. RESULTS: We identified six new families with evidence for linkage to the chromosome 9p. Cumulative multipoint LOD score values were positive between markers D9S1121 and D9S301, reaching a peak of 8.0 at marker D9S248. Haplotype reconstruction defined the telomeric boundary at marker AFM218xg11, slightly narrowing the candidate interval. We found no disease-causing mutations by sequencing 29 candidate genes including IFT74 and no copy number variations in the 9p region. The mean age at onset was 57.9 +/- 10.3 years (range, 41-84), with wide heterogeneity within and among families suggesting age-dependant penetrance. The patients presented isolated FTD (32%), isolated MND (29%), or both disorders (39%). The general characteristics of the disease did not differ, except for an older age at onset and shorter disease duration in the 9p-linked compared to nonlinked families. TDP-43-positive neuronal cytoplasmic inclusions were found in cortex and spinal cord in 3 patients. CONCLUSIONS: This study increases the number of 9p-linked families now reported and shows that this locus may have a major effect on frontotemporal dementia (FTD) and motor neuron disease (MND). Considering our results, the causative gene might be implicated in at least 60% of the families with FTD-MND disorder.

Wernicke encephalopathy and Creutzfeldt-Jakob disease.

We assessed the prevalence of Wernicke encephalopathy (WE) in all 657 cases suspected of Creutzfeldt-Jakob (CJD) referred from 2001 to 2006 to the French Neuropathology Network of CJD. Clinical, biological and imaging data were reviewed when the diagnosis of WE was made at autopsy. No CJD was found in five cases suspected of sporadic CJD. In these five cases, myoclonus had been observed in four, CSF 14-3-3 protein in two. In 14 other cases, WE was combined with CJD, 13 of which were sporadic. These belonged mainly to the molecular variants of sporadic CJD associated with a long duration of disease. This stresses the necessity of remaining alert to the diagnosis of WE when CJD is suspected.

[The neuropathology of sleep in human neurodegenerative diseases]. / Neuropathologie du sommeil des maladies neurodégénératives humaines.

The neuropathology of human sleep remains an ill-defined issue. The data concerning the main structures of human brain areas involved, or supposed to be implicated, in sleep organisation are reviewed. Five levels of organisation can be schematically recognized: (i) the ascending arousal system, (ii) the non REM and REM systems (iii) regulated by hypothalamic areas, (iv) and the biological clock, (v) modulated by a number of "allostatic" influences. These are briefly described, with emphasis on the location of structures involved in humans, and on the recently revised concepts. Current knowledge on the topography of lesions associated with the main sleep disorders in degenerative diseases is recalled, including REM sleep behavior disorders, restless legs syndrome and periodic leg movements, sleep apneas, insomnia, excessive daily sleepiness, secondary narcolepsy and disturbed sleep-wake rhythms. The lesions of sleep related structures observed in early and late stages of four degenerative diseases are then reviewed. Two synucleinopathies (Lewy lesions associated disorders, including Parkinson's disease and Dementia with Lewy bodies, and Multiple System Atrophy) and two tauopathies (Progressive Supranuclear Palsy and Alzheimer's disease) are dealt with. The distribution of lesions usually found in affected patients fit with that expected from the prevalence of different sleep disorders in these diseases. This confirms the current opinion that these disorders depend on the distribution of lesions rather than on their biochemical nature. Further studies might throw insight on the mechanism of normal and pathological sleep in humans, counterpart of the increasing knowledge provided by animal models. Specially designed prospective clinicopathological studies including peculiar attention to sleep are urgently needed.

Pathology of tumors of the pineal region.

Tumors of the pineal region are rare and relatively few centers around the world have published substantial numbers of carefully studied cases. This review gives a historical account of our understanding of the normal pineal and the evolution of the classification of tumors and other mass lesions of the pineal region in human beings. Based on our experience over the past 30 years, a working classification is proposed and recent advances in the neuropathology of these lesions are discussed.

Dyslipidemia is a protective factor in amyotrophic lateral sclerosis.

BACKGROUND: Amyotrophic lateral sclerosis (ALS) is the most serious form of degenerative motor neuron disease in adults, characterized by upper and lower motor neuron degeneration, skeletal muscle atrophy, paralysis, and death. High prevalence of malnutrition and weight loss adversely affect quality of life. Moreover, two thirds of patients develop a hypermetabolism of unknown cause, leading to increased resting energy expenditure. Inasmuch as lipids are the major source of energy for muscles, we determined the status of lipids in a population of patients with ALS and investigated whether lipid contents may have an impact on disease progression and survival. METHODS: Blood concentrations of triglycerides, cholesterol, low-density lipoprotein (LDL), and high-density lipoprotein (HDL) were measured in a cohort of 369 patients with ALS and compared to a control group of 286 healthy subjects. Postmortem histologic examination was performed on liver specimens from 59 other patients with ALS and 16 patients with Parkinson disease (PD). RESULTS: The frequency of hyperlipidemia, as revealed by increased plasma levels of total cholesterol or LDL, was twofold higher in patients with ALS than in control subjects. As a result, steatosis of the liver was more pronounced in patients with ALS than in patients with PD. Correlation studies demonstrated that bearing an abnormally elevated LDL/HDL ratio significantly increased survival by more than 12 months. CONCLUSIONS: Hyperlipidemia is a significant prognostic factor for survival of patients with amyotrophic lateral sclerosis. This finding highlights the importance of nutritional intervention strategies on disease progression and claims our attention when treating these patients with lipid-lowering drugs.

High power phased array prototype for clinical high intensity focused ultrasound : applications to transcostal and transcranial therapy.

Bursts of focused ultrasound energy three orders of magnitude more intense than diagnostic ultrasound became during the last decade a noninvasive option for treating cancer from breast to prostate or uterine fibroid. However, many challenges remain to be addressed. First, the corrections of distortions induced on the ultrasonic therapy beam during its propagation through defocusing obstacles like skull bone or ribs remain today a technological performance that still need to be validated clinically. Secondly, the problem of motion artifacts particularly important for the treatment of abdominal parts becomes today an important research topic. Finally, the problem of the treatment monitoring is a wide subject of interest in the growing HIFU community. For all these issues, the potential of new ultrasonic therapy devices able to work both in Transmit and Receive modes will be emphasized. A review of the work under achievement at L.O.A. using this new generation of HIFU prototypes on the monitoring, motion correction and aberrations corrections will be presented.

Reversible encephalopathy associated with cholesterol embolism syndrome: magnetic resonance imaging and pathological findings.

We describe a patient found to have acute diffuse and reversible encephalopathy on magnetic resonance imaging (MRI) associated with cholesterol emboli syndrome (CES). The initial MRI showed extensive white matter, basal ganglia and cortical damage without evidence of brain infarction. Dramatic clinical and MRI improvement was observed with corticosteroids. Pathologically, cholesterol crystal emboli were found in the lumen of skin and brain arteries and were associated with varying degrees of inflammation of the arteriole wall. This case suggests that CES may be responsible for extensive, acute and reversible encephalopathy underlined by an inflammation of brain arteries.

How a neuropsychiatric brain bank should be run: a consensus paper of Brainnet Europe II.

The development of new molecular and neurobiological methods, computer-assisted quantification techniques and neurobiological investigation methods which can be applied to the human brain, all have evoked an increased demand for post-mortem tissue in research. Psychiatric disorders are considered to be of neurobiological origin. Thus far, however, the etiology and pathophysiology of schizophrenia, depression and dementias are not well understood at the cellular and molecular level. The following will outline the consensus of the working group for neuropsychiatric brain banking organized in the Brainnet Europe II, on ethical guidelines for brain banking, clinical diagnostic criteria, the minimal clinical data set of retrospectively analyzed cases as well as neuropathological standard investigations to perform stageing for neurodegenerative disorders in brain tissue. We will list regions of interest for assessments in psychiatric disorder, propose a dissection scheme and describe preservation and storage conditions of tissue. These guidelines may be of value for future implementations of additional neuropsychiatric brain banks world-wide.

Nodal, paranodal and juxtaparanodal axonal proteins during demyelination and remyelination in multiple sclerosis.

Saltatory conduction in myelinated fibres depends on the specific molecular organization of highly specialized axonal domains at the node of Ranvier, the paranodal and the juxtaparanodal regions. Voltage-gated sodium channels (Na(v)) have been shown to be deployed along the naked demyelinated axon in experimental models of CNS demyelination and in multiple sclerosis lesions. Little is known about aggregation of nodal, paranodal and juxtaparanodal constituents during the repair process. We analysed by immunohistochemistry on free-floating sections from multiple sclerosis brains the expression and distribution of nodal (Na(v) channels), paranodal (paranodin/Caspr) and juxtaparanodal (K(v) channels and Caspr2) molecules in demyelinated and remyelinated lesions. Whereas in demyelinated lesions, paranodal and juxtaparanodal proteins are diffusely distributed on denuded axons, the distribution of Na(v) channels is heterogeneous, with a diffuse immunoreactivity but also few broad Na(v) channel aggregates in all demyelinated lesions. In contrast to the demyelinated plaques, all remyelinated lesions are characterized by the detection of aggregates of Na(v) channels, paranodin/Caspr, K(v) channels and Caspr2. Our data suggest that these aggregates precede remyelination, and that Na(v) channel aggregation is the initial event, followed by aggregation of paranodal and then juxtaparanodal axonal proteins. Remyelination takes place in multiple sclerosis tissue but myelin repair is often incomplete, and the reasons for this remyelination deficit are many. We suggest that a defect of Na(v) channel aggregation might be involved in the remyelination failure in demyelinated lesions with spared axons and oligodendroglial cells.

Devic's neuromyelitis optica: study of nine cases.

OBJECTIVE: Multiple sclerosis (MS) is by far the most popular diagnosis for patients with multifocal neurological disease. Owing to demyelinating inflammatory non-necrotic plaques of the white matter, MS can give remitting symptoms of virtually every part of the central nervous system. Corticosteroids are usually helpful. Devic's neuromyelitis optica (DNMO) is a neurological disease involving only the optic nerves and the spinal cord, where demyelination evolves towards necrosis and atrophy; the prognosis is poor and no satisfactory treatment is known. The objectives of this study are to describe clinical, biological, pathological and radiological data of patients with DNMO and to differentiate DNMO from MS. MATERIAL AND METHODS: We studied the files of 14 patients diagnosed with possible DNMO in three French hospitals between 1980 and 1999 and reviewed the literature. RESULTS: Nine patients were included as definite DNMO. Five were excluded because they did not fulfil the diagnostic criteria. For the nine patients with definite DNMO, DNMO was either monophasic or multiphasic. The prognosis was generally poor: two patients died and five others developed severe disability such as blindness, para or quadriplegia or both. Cerebrospinal fluid study and neuroimaging were essential to confirm the diagnosis of DNMO. Various immunosuppressive treatments generally failed to benefit the patients. CONCLUSION: In the literature (as well as our 14 initial patients) only a few cases of patients described as suffering from DNMO fulfilled the diagnostic criteria. The others showed evidence that another disease like MS was involved. We stress that inclusion and exclusion criteria have to be kept in mind to differentiate clearly DNMO from MS and other central nervous system white matter diseases.

The relationship between Bunina bodies, skein-like inclusions and neuronal loss in amyotrophic lateral sclerosis.

Specific pathological hallmarks have been described in amyotrophic lateral sclerosis (ALS), which include motor neuronal loss, Bunina bodies (BBs) and skein like inclusions (SLIs). We investigated the relation between these three lesions in the cervical and lumbar anterior horns and the hypoglossal nuclei of 20 ALS patients and 9 controls using a quantitative light microscopy study. Immunohistochemistry with anti-cystatin C and anti-ubiquitin was used to detect the BBs and SLIs, respectively. A significant relation between the severity of neuronal loss and the proportion of SLI-containing neurons was found in the spinal cord, whereas no relation was found with BBs. We therefore propose that BBs and SLIs participate in two different steps of the cascade leading to neuronal loss.

Long-term survival after gene therapy for a recurrent glioblastoma.

A patient presenting with a recurrent glioblastoma (GBM) survived 3 years after suicide gene therapy and finally died of a disseminated breast cancer with no indication of tumor recurrence on MRI. Postmortem analysis showed no evidence of recurrence of the GBM, neither near the initial tumor localization nor in any other area of the brain. Such an evolution is unusual in the course of this disease and may suggest in this particular case a cure of the GBM.