Cerebral biochemical pathways in experimental autoimmune encephalomyelitis and adjuvant arthritis: a comparative metabolomic study.

Many diseases, including brain disorders, are associated with perturbations of tissue metabolism. However, an often overlooked issue is the impact that inflammations outside the brain may have on brain metabolism. Our main goal was to study similarities and differences between brain metabolite profiles of animals suffering from experimental autoimmune encephalomyelitis (EAE) and adjuvant arthritis (AA) in Lewis rat models. Our principal objective was the determination of molecular protagonists involved in the metabolism underlying these diseases. EAE was induced by intraplantar injection of complete Freund's adjuvant (CFA) and spinal-cord homogenate (SC-H), whereas AA was induced by CFA only. Naive rats served as controls (n = 9 for each group). Two weeks after inoculation, animals were sacrificed, and brains were removed and processed for metabolomic analysis by NMR spectroscopy or for immunohistochemistry. Interestingly, both inflammatory diseases caused similar, though not identical, changes in metabolites involved in regulation of brain cell size and membrane production: among the osmolytes, taurine and the neuronal marker, N-acetylaspartate, were decreased, and the astrocyte marker, myo-inositol, slightly increased in both inoculated groups compared with controls. Also ethanolamine-containing phospholipids, sources of inflammatory agents, and several glycolytic metabolites were increased in both inoculated groups. By contrast, the amino acids, aspartate and isoleucine, were less concentrated in CFA/SC-H and control vs. CFA rats. Our results suggest that inflammatory brain metabolite profiles may indicate the existence of either cerebral (EAE) or extra-cerebral (AA) inflammation. These inflammatory processes may act through distinct pathways that converge toward similar brain metabolic profiles. Our findings open new avenues for future studies aimed at demonstrating whether brain metabolic effects provoked by AA are pain/stress-mediated and/or due to the presence of systemic proinflammatory molecules. Regardless of the nature of these mechanisms, our findings may be of interest for future clinical studies, e.g. by in-vivo magnetic resonance spectroscopy.

VMA21 deficiency prevents vacuolar ATPase assembly and causes autophagic vacuolar myopathy.

X-linked Myopathy with Excessive Autophagy (XMEA) is a childhood onset disease characterized by progressive vacuolation and atrophy of skeletal muscle. We show that XMEA is caused by hypomorphic alleles of the VMA21 gene, that VMA21 is the diverged human ortholog of the yeast Vma21p protein, and that like Vma21p, VMA21 is an essential assembly chaperone of the vacuolar ATPase (V-ATPase), the principal mammalian proton pump complex. Decreased VMA21 raises lysosomal pH which reduces lysosomal degradative ability and blocks autophagy. This reduces cellular free amino acids which leads to downregulation of the mTORC1 pathway, and consequent increased macroautophagy resulting in proliferation of large and ineffective autolysosomes that engulf sections of cytoplasm, merge, and vacuolate the cell. Our results uncover a novel mechanism of disease, namely macroautophagic overcompensation leading to cell vacuolation and tissue atrophy.

Correlation of clinicoserologic and pathologic classifications of inflammatory myopathies: study of 178 cases and guidelines for diagnosis.

The idiopathic inflammatory myopathies (IIM) are acquired muscle diseases characterized by muscle weakness and inflammation on muscle biopsy. Clinicoserologic classifications do not take muscle histology into account to distinguish the subsets of IIM. Our objective was to determine the pathologic features of each serologic subset of IIM and to correlate muscle biopsy results with the clinicoserologic classification defined by Troyanov et al, and with the final diagnoses. We retrospectively studied a cohort of 178 patients with clinicopathologic features suggestive of IIM with the exclusion of inclusion body myositis. At the end of follow-up, 156 of 178 cases were still categorized as IIM: pure dermatomyositis, n = 44; pure polymyositis, n = 14; overlap myositis, n = 68; necrotizing autoimmune myopathy, n = 8; cancer-associated myositis, n = 18; and unclassified IIM, n = 4. The diagnosis of IIM was ruled out in the 22 remaining cases. Pathologic dermatomyositis was the most frequent histologic picture in all serologic subsets of IIM, with the exception of patients with anti-Ku or anti-SRP autoantibodies, suggesting that it supports the histologic diagnosis of pure dermatomyositis, but also myositis of connective tissue diseases and cancer-associated myositis. Unspecified myositis was the second most frequent histologic pattern. It frequently correlated with overlap myositis, especially with anti-Ku or anti-PM-Scl autoantibodies. Pathologic polymyositis was rare and more frequently correlated with myositis mimickers than true polymyositis. The current study shows that clinicoserologic and pathologic data are complementary and must be taken into account when classifying patients with IIM patients. We propose guidelines for diagnosis according to both clinicoserologic and pathologic classifications, to be used in clinical practice.

The MFN2 gene is responsible for mitochondrial DNA instability and optic atrophy 'plus' phenotype.

MFN2 and OPA1 genes encode two dynamin-like GTPase proteins involved in the fusion of the mitochondrial membrane. They have been associated with Charcot-Marie-Tooth disease type 2A and autosomal dominant optic atrophy, respectively. We report a large family with optic atrophy beginning in early childhood, associated with axonal neuropathy and mitochondrial myopathy in adult life. The clinical presentation looks like the autosomal dominant optic atrophy 'plus' phenotype linked to OPA1 mutations but is associated with a novel MFN2 missense mutation (c.629A>T, p.D210V). Multiple mitochondrial DNA deletions were found in skeletal muscle and this observation makes MFN2 a novel gene associated with 'mitochondrial DNA breakage' syndrome. Contrary to previous studies in patients with Charcot-Marie-Tooth disease type 2A, fibroblasts carrying the MFN2 mutation present with a respiratory chain deficiency, a fragmentation of the mitochondrial network and a significant reduction of MFN2 protein expression. Furthermore, we show for the first time that impaired mitochondrial fusion is responsible for a deficiency to repair stress-induced mitochondrial DNA damage. It is likely that defect in mitochondrial DNA repair is due to variability in repair protein content across the mitochondrial population and is at least partially responsible for mitochondrial DNA instability.

Nemaline myopathy caused by mutations in the nebulin gene may present as a distal myopathy.

Mutations in the nebulin gene are the main cause of autosomal recessive nemaline myopathy, with clinical presentations ranging from mild to severe disease. We have previously reported a nonspecific distal myopathy caused by homozygous missense mutations in the nebulin gene in six Finnish patients from four different families. Here we describe three non-Finnish patients in two unrelated families with distal nemaline myopathy caused by four different compound heterozygous nebulin mutations, only one of which is a missense mutation. One of the mutations has previously been identified in one family with the severe form of nemaline myopathy. We conclude that nemaline myopathy and distal myopathy caused by nebulin mutations form a clinical and histological continuum. Nemaline myopathy should be considered as a differential diagnosis in patients presenting with an early-onset predominantly distal myopathy.

[Potassium channelopathies and Morvan's syndromes]. / Les canalopathies potassiques, autour du syndrome de Morvan.

Interest in Morvan's disease or syndrome has grown, owing to its close links with various potassium channelopathies. Potassium is crucial for gating mechanisms (channel opening and closing), and especially for repolarization. Defective potassium regulation can lead to neuronal hyperexcitability. There are three families of potassium channels: voltage-gated potassium channels or VGKC (Kv1.1-Kv1.8), inward rectifier K+ channels (Kir), and two-pore channels (K2p). VGK channels are the commonest, and especially those belonging to the Shaker group (neuromyotonia and Morvan's syndrome, limbic encephalitis, and type 1 episodic ataxia). Brain and heart K+ channelopathies are a separate group due to KCNQ1 mutation (severe type 2 long QT syndrome). Kv7 channel mutations (in KNQ2 and KCNQ3) are responsible for benign familial neonatal seizures. Mutation of the Ca+ activated K+ channel gene causes epilepsy and paroxysmal dyskinesia. Inward rectifier K+ channels regulate intracellular potassium levels. The DEND syndrome, a treatable channelopathy of the brain and pancreas, is due to KCNJ1 mutation. Andersen's syndrome, due to KCNJ2 mutation, is characterized by periodic paralysis, cardiac arrythmia, and dysmorphia. Voltage-insensitive K2p channelopathies form a final group.

Myopathy with hexagonally cross-linked crystalloid inclusions: delineation of a clinico-pathological entity.

A novel myopathy characterized by hexagonally cross-linked tubular arrays has been reported in five patients. We studied the clinical and histopathological features of five additional unrelated patients with this myopathy. Patients experienced exercise intolerance with exercise-induced myalgia and weakness, without rhabdomyolysis. One patient additionally presented mild permanent pelvic girdle muscle weakness. Age at onset varied between 13 and 56 years. The inclusions were eosinophilic on H and E, bright red with modified Gomori's trichrome stains, present in type 2 fibers, and revealed immunoreactivity selectively for a caveolin-3-antibody. Ultrastructurally, the inclusions showed a highly organized, hexagonally cross-linked crystalloid structure. Mutations in the caveolin-3 encoding gene were excluded. Biochemical assessment of glycogenolysis in muscle was normal. Inherited or sporadic myopathy with hexagonally cross-linked tubular arrays is associated with a homogeneous clinical and histopathological phenotype. This myopathy should be included in the differential diagnosis of patients with exercise intolerance and myalgia.

Lethal injection of potassium chloride: first description of the pathological appearance of organs.

Lethal injection of potassium chloride (KCl) can be used as a method of either suicide or homicide. As biological tests are still inadequate to differentiate endogenous from exogenous potassium, at the scene of death the cause can only be suspected. We wished to determine the usefulness of conventional pathological examination in this context and carried out a study in four fetuses after medical termination of pregnancy for serious disease. Pregnancy was terminated by KCl injection in two cases and by injection of lidocaine and sufentanil in the other two cases. In each of the two fetuses in which KCl injection was performed, macroscopic examination showed whitish deposits on the tissues and histological examination showed clumps of lanceolate crystals in the internal organs. In the two fetuses which received lidocaine and sufentanil injection, no deposits were visible on macroscopic examination and no crystals were seen on histological examination. These findings suggest that pathological study may have useful applications in forensic medicine when death by potassium injection is suspected.

Non-lethal neonatal neuromuscular variant of glycogenosis type IV with novel GBE1 mutations.

We report a recent case of the severe congenital variant of glycogen storage disease type IV with prolonged survival. The patient was found to be a compound heterozygote for two novel mutations, a missense mutation in exon 5 (p.H188P, c.563A>C) and a severe mutation in intron 5 (c.691+2T>C). We propose that the genotype and the quality of medical care may account for the severe but non-lethal phenotype.

Interpretation of neuropathological lesions: its limitations in medico-legal experts' reports.

Aggressive or paradoxical behaviour may reflect an organic dementia. The most frequent is Alzheimer's disease, which results from an abnormal structural conformation of tubulin-associated protein (tau) and beta-amyloid protein that, respectively, aggregate in certain neurons as intracellular neurofibrillary tangles (NFTs) and in the extracellular environment as senile plaques. These lesions progress in the brain tissue according to the stages described by Braak and Braak. Staging of neurofibrillary pathology has proven anatomical and clinical correlation, which can be used in a medico-legal procedure. We report two cases demonstrating discrepancies between anatomical and clinical features, which should encourage medical expert to prudence when interpreting neuropathological reports.

A TPM3 mutation causing cap myopathy.

Cap disease is a rare congenital myopathy associated with skeletal malformations and respiratory involvement. Abnormally arranged myofibrils taking the appearance of a "cap" are the morphological hallmark of this entity. We report a case of cap disease concerning a 42-year-old man, without any family history and presenting a p.Arg168His mutation on the TPM3 gene. His first biopsy at 7years had only shown selective type I hypotrophy. Mutations of TPM3 gene have been found in nemaline myopathy, congenital fiber type disproportion, but never before in cap disease.

VMA21 deficiency causes an autophagic myopathy by compromising V-ATPase activity and lysosomal acidification.

X-linked myopathy with excessive autophagy (XMEA) is a childhood-onset disease characterized by progressive vacuolation and atrophy of skeletal muscle. We show that XMEA is caused by hypomorphic alleles of the VMA21 gene, that VMA21 is the diverged human ortholog of the yeast Vma21p protein, and that like Vma21p it is an essential assembly chaperone of the V-ATPase, the principal mammalian proton pump complex. Decreased VMA21 raises lysosomal pH, which reduces lysosomal degradative ability and blocks autophagy. This reduces cellular free amino acids, which upregulates the mTOR pathway and mTOR-dependent macroautophagy, resulting in proliferation of large and ineffective autolysosomes that engulf sections of cytoplasm, merge together, and vacuolate the cell. Our results uncover macroautophagic overcompensation leading to cell vacuolation and tissue atrophy as a mechanism of disease.

Rapid diagnosis of human prion disease using streptomycin with tonsil and brain tissues.

The use of streptomycin in the pathological prion protein (PrP(sc)) detection procedures represents a new and attractive way for diagnostic purpose. With this agent, western blot readily detected PrP(sc) in 263K scrapie hamster and C57Bl/6 wild-type mice challenged with C506M3 scrapie strain. Our aim was to evaluate this new diagnosis procedure in the field of human transmissible spongiform encephalopathies (TSEs). First, we had confirmed the ability of streptomycin to precipitate PrP(res) from human brain of Creutzfeldt-Jakob disease (CJD) patient. Second, we compared the detection of PrP(res) with streptomycin against three other protocols using other precipitations. Then we assessed PrP(res) detection with streptomycin in 98 brain tissue samples from various aetiologies of human TSEs and 52 brain samples from other dementia. Finally, we applied this protocol for tonsils examination of five patients suspected of variant CJD (v-CJD). Sensitivity and specificity obtained with the streptomycin protocol were both 100% on brain tissue. For tonsil tissues, PrP(res) was clearly identified in the two post-mortem confirmed v-CJD cases, whereas no characteristic three-band pattern was seen in the three confirmed non-v-CJD samples. In this study, streptomycin demonstrated its efficiency to detect PrP(res) both in the central nervous system and in the lymphoid tissue without practical difficulty and with rapid preparation. Because of its ability to act as a good agent for PrP(sc) examination in different tissues, recovery of PrP(sc) in biological fluids using streptomycin should open further perspectives of applications in CJD diagnostics. Streptomycin effects in vivo might thus also be questioned.

Striking phenotypic variability in two familial cases of myosin storage myopathy with a MYH7 Leu1793pro mutation.

Myosin Storage Myopathies (MSM) have emerged as a new group of inherited myopathies with heterogenous clinical severity and age of onset. We have identified in a woman and her daughter, a pLeu1793Pro mutation in MYH7. This mutation has already been reported to be associated with MSM presenting as neonatal hypotony. Our index case complained of proximal muscle weakness at age 30. Her daughter presented at birth with a cardiomyopathy without any skeletal muscle involvement. This report underlines the clinical variability of MSM even with a given mutation or in a same family.

Analysis of the DYSF mutational spectrum in a large cohort of patients.

Dysferlinopathies belong to the heterogeneous group of autosomal recessive muscular dystrophies. Mutations in the gene encoding dysferlin (DYSF) lead to distinct phenotypes, mainly Limb Girdle Muscular Dystrophy type 2B (LGMD2B) and Miyoshi myopathy (MM). Here, we analysed the mutational data from the largest cohort described to date, a cohort of 134 patients, included based on clinical suspicion of primary dysferlinopathy and/or dysferlin protein deficiency identified on muscle biopsy samples. Data were compiled from 38 patients previously screened for mutations in our laboratory (Nguyen, et al., 2005; Nguyen, et al., 2007), and 96 supplementary patients screened for DYSF mutations using genomic DHPLC analysis, and subsequent sequencing of detected variants, in a routine diagnostic setting. In 89 (66%) out of 134 patients, molecular analysis identified two disease causing mutations, confirming the diagnosis of primary Dysferlinopathy on a genetic basis. Furthermore, one mutation was identified in 30 patients, without identification of a second deleterious allele. We are currently developing complementary analysis for patients in whom only one or no disease-causing allele could be identified using the genomic screening procedure. Altogether, 64 novel mutations have been identified in this cohort, which corresponds to approximately 25% of all DYSF mutations reported to date. The mutational spectrum of this cohort significantly shows a higher proportion of nonsense mutations, but a lower proportion of deleterious missense changes as compared to previous series. (c) 2008 Wiley-Liss, Inc.

Type 2 myotonic dystrophy can be predicted by the combination of type 2 muscle fiber central nucleation and scattered atrophy.

The diagnosis of Type 2 myotonic dystrophy (DM2/proximal myotonic myopathy) is often overlooked because of a nonspecific clinical presentation and muscle biopsy findings of a "denervation-like" pattern of unknown specificity that combines increased fiber size variation, central nucleation, small angulated fibers, Type 2 fiber atrophy, and nuclear clumps. We determined the presence of these features in 104 patients designated as having an unidentified myopathy from a series of 2,100 muscle biopsies. Because CCUG expansions form pathogenic ribonuclear accumulations that can be detected by in situ hybridization, we validated and then used automated (CCUG)8 in situ hybridization as a reference standard to evaluate the value of each histologic feature for DM2 detection, identifying 8 DM2-positive and 96 DM2-negative cases. Multivariate analyses identified the combination of Type 2 fiber atrophy and central nucleation as the most predictive of DM2 (sensitivity, 1.0; specificity, 0.92). These features were mutually exclusive in non-DM2 patients (p < 0.0001). The relevance of this combination of features was confirmed in an additional independent series (15 DM2-positive vs 17 DM2-negative). Further investigation revealed that central nucleation selectively affects Type 2 fibers in DM2 and, conversely, that it affects Type 1 fibers in DM1 (p < 0.0001). These results will facilitate the routine detection of DM2 and further support the concept that DM2 has a distinct pathophysiology involving type 2 myofibers.

[Limbic encephalitis--evolving concepts]. / L'encéphalite limbique--evolution des concepts.

Limbic encephalitis is an inflammatory disease localized to the "grand lobe limbique" defined by Broca in 1878, sometimes restricted to the hippocampus, but sometimes including extralimbic abnormalities. The main features are subacute onset, short-term memory disorders and cognitive impairment, temporal seizures, and hippocampic changes on MRI. A list of underlying causes has recently been published Infectious causes used to be frequent (mainly herpes simplex virus). Paraneoplastic limbic encephalitis is characterized by the presence of various onconeural antibodies, such as AntiHu and ANNA3 (bronchial small cell carcinoma), AntiMa2 (testicular tumor), AntiCV2 (lymphoma, thymoma,...). No such antibodies are detected in 40% of patients. The prognosis of these forms is poor. Voltage-gated potassium channel-associated limbic encephalopathies are due to antibodies targeting potassium channels. Mutations of the genes encoding the Kv11 and Kv12 subunits are responsible for several Shaker syndromes, including neuromyotonia, Morvan's disease, type I episodic ataxia, and limbic encephalitis with hyponatremia. Plasma exchanges and immunotherapy are effective. In patients without detectable antibodies, hippocampic anti-neuropil antibodies should be sought, particularly those targeting N-methyl-D-aspartate receptors. Ovarian teratoma is the usual cause of this type of encephalitis. Surgery and immunotherapy are effective. These disorders have been categorized into those associated with antibodies targeting intracellular antigens (poor-prognosis paraneoplastic encephalitis) and those associated with antibodies targeting antigens reacting with cellular membranes (potassium channelopathies and antineuropil antibodies), which respond to immunotherapy and carry a better prognosis. Limbic encephalitis can also reveal Hodgkin's disease, as in a case observed by the authors.

Molecular characterization of myophosphorylase deficiency (McArdle disease) in 34 patients from Southern France: identification of 10 new mutations. Absence of genotype-phenotype correlation.

We report on 31 patients and 3 affected siblings (17 males and 17 females) from Southern France with McArdle disease (two from Spanish and three from Portuguese background). Molecular analysis revealed the presence of five previously described mutations: the common p.R50X nonsense mutation, the p.R94W and p.V456M missense mutations, the p.K609K conservative mutation which generates an aberrant splicing, and the p.K754fs frameshift mutation; and 10 new molecular defects: eight missense mutations at homozygous (p.G136D) or heterozygous state (p.T379M, p.G449R, p.T488I, p.R490Q, p.R570Q, p.R590H, and p.R715W), one nonsense mutation p.R650X and one deletion (p.delK170). Our results confirm that the p.R50X nonsense mutation is also the most common associated with myophosphorylase deficiency in the Southern French population: 21 of 25 French unrelated patients (15 homozygous and six heterozygous, i.e., 72% of the mutated alleles). Two patients, one from Algeria and one from Tunisia, were homozygous for a previously identified missense mutation p.V456M in a Moroccan subject. Our findings further demonstrate molecular heterogeneity of myophosphorylase deficiency, absence of genotype-phenotype correlation and expand the already crowded map of mutations within the myophosphorylase gene. Our study also provides evidence for increased medical interest of malignant hyperthermia susceptibility (MHS) because of 34 McArdle disease patients, three and two affected siblings were contracture-tested and found to be positive.

Metabosensitive afferent fiber responses after peripheral nerve injury and transplantation of an acellular muscle graft in association with schwann cells.

Studies dedicated to the repair of peripheral nerve focused almost exclusively on motor or mechanosensitive fiber regeneration. Poor attention has been paid to the metabosensitive fibers from group III and IV (also called ergoreceptor). Previously, we demonstrated that the metabosensitive response from the tibialis anterior muscle was partially restored when the transected nerve was immediately sutured. In the present study, we assessed motor and metabosensitive responses of the regenerated axons in a rat model in which 1 cm segment of the peroneal nerve was removed and immediately replaced by an autologous nerve graft or an acellular muscle graft. Four groups of animals were included: control animals (C, no graft), transected animals grafted with either an autologous nerve graft (Gold Standard-GS) or an acellular muscle filled with Schwann Cells (MSC) or Culture Medium (MCM). We observed that (1) the tibialis anterior muscle was atrophied in GS, M(SC) and M(CM) groups, with no significant difference between grafted groups; (2) the contractile properties of the reinnervated muscles after nerve stimulation were similar in all groups; (3) the metabosensitive afferent responses to electrically induced fatigue was smaller in M(SC) and MCM groups; and (4) the metabosensitive afferent responses to two chemical agents (KCl and lactic acid) was decreased in GS, M(SC) and M(CM) groups. Altogether, these data indicate a motor axonal regeneration and an immature metabosensitive afferent fiber regrowth through acellular muscle grafts. Similarities between the two groups grafted with acellular muscles suggest that, in our conditions, implanted Schwann cells do not improve nerve regeneration. Future studies could include engineered conduits that mimic as closely as possible the internal organization of uninjured nerve.