Search

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.

Pituicytoma is a rare benign primary tumor of the neurohypophysis, occurring in the sellar and suprasellar spaces. We report here three new cases with immunohistochemical and electron microscopic study. Particular attention was paid to the expression of some cell adhesion molecules. These tumors were characterized by bundles of elongated cells strongly immunoreactive to anti-vimentin, S-100 protein, neural cell adhesion molecule and neuron-specific enolase antibodies. Glial fibrillary acidic protein (GFAP) was not recorded. It expressed the very late antigen alpha2 (VLAalpha2), but not VLAalpha5, and lacked epithelial markers expression (epithelial membrane antigen, E-cadherin), and specific neuronal markers (synaptophysin, chromogranin, neurofilament). Staining for pituitary hormones was negative. At the ultrastructural level, tumor/blood vessel basal lamina and cytoplasmic intermediate filaments were observed but desmosome or pericellular basal lamina were lacking. In one case few secretory granules were recorded. Differential diagnoses include granular cell tumors, pilocytic astrocytomas and spindle cell tumors such as solitary fibrous tumors, fibroblastic meningiomas and schwannomas. However, the unique pattern of antigenic expression and ultrastructural features of pituicytomas distinguish this rare tumor. As a subpopulation of pituicytes (which are distinctive glial cells of the neurophypophysis), some pituicytomas do not expressed GFAP. This suggests that pituicytomas presumably arise from pituicytes at various stages of their differentiation.

Colchicine, a microtubule polymerization inhibitor, can very occasionally induce myopathy. We report two cases of colchicine myopathy. Both patients presented with myalgia and proximal muscle weakness. The first patient, an 80-year-old woman, had chronic renal failure related to renal amyloidosis. She had been treated by colchicine for 4 months. The second, a 75-year-old man with normal renal function, suffering from gout, was treated by colchicine for 3 weeks. Muscle biopsies displayed the same alterations, but the degree of severity was different. Conventional histology revealed vacuolar changes characterized by acid phosphatase-positive vacuoles and myofibrillar disarray foci. The lesions were selective for type I fibers. Ultrastructural study demonstrated autophagic vacuoles. Most of the vacuoles expressed dystrophin but not merosin. Several fibers reacted with anti-MHC class I antibody and granular deposits of membrane attack complex were observed on the surface of numerous myofibers. Anti-alphaB-crystallin antibody strongly reacted with vacuolar content. Physiopathologically, microtubules are primordial for vesicle movements and colchicine induces autophagic vacuole accumulation by preventing their fusion with lysosomes. The selective type I involvement is probably due to the higher tubulin amount in type I fibers. AlphaB-crystallin overexpression is related to its microtubule protection properties. Moreover, we suggest that vacuoles randomly floating in sarcoplasm might occasionally meet the plasma membrane and open in the extracellular space, leading to complement activation. Accurate diagnosis of colchicine myopathy is relevant because the treatment is based on colchicine interruption.

The idiopathic inflammatory myopathies (IIM), including dermatomyositis (DM), polymyosititis (PM) and inclusion body myositis (IBM), are a group of autoimmune diseases characterized by chronic lymphocytic and macrophagic infiltration in muscle. The mechanism for recruitment of these cells probably involves chemokines. We have previously reported that monocyte chemoattractant protein-1 (MCP-1), a beta chemokine, seems to play a major role in mononuclear cell recruitment especially in DM. Here we have investigated the distribution of the main MCP-1 receptors CCR2A and CCR2B in IIM by polymerase chain reaction (PCR), immunohistochemistry and in situ hybridization. We have shown by reverse transcription-PCR that both CCR2A and CCR2B were expressed at low level in normal muscle and that CCR2A was up-regulated in IIM (P=0.02) and was higher in PM and IBM than in DM (P=0.04). By immunohistochemistry and in situ hybridization we have observed that CCR2 isoforms were expressed by different cell subsets in both normal and IIM muscle. CCR2A was expressed in vessel walls and by some mononuclear cells, especially in cells involved in partial invasion in PM and IBM. CCR2B expression was observed in all satellite cells, in the muscular domain of neuromuscular junctions and in some regenerative fibers of IIM, but not in inflammatory exudates. In conclusion, the present study highlights the major role played by MCP-1 and its counter-receptor CCR2 in the pathophysiology of IIM, and shows that the CCR2 receptors are cell specific. The variation of the total amount of CCR2A and its local distribution according to the type of IIM might be a new path towards the understanding of the constitution of mononuclear infiltrates in IIM.

The idiopathic inflammatory myopathies (IIM), including dermatomyositis (DM), polymyositis (PM), and inclusion body myositis (IBM), are a group of autoimmune diseases characterized by the recruitment of lymphocytes and monocytes to the site of affection. The mechanism for recruitment of these cells likely involves chemokines. The monocyte chemoattractant protein-1 (MCP-1), a chemoattractant to T lymphocytes and monocytes, may play an important role in the pathogenesis of IIM. Frozen muscular tissues were obtained from eight cases of DM, five PM, and four IBM. We investigated the MCP-1 expression by the reverse transcription-PCR technique, immunohistochemistry and in situ hybridization. MCP-1 mRNA was markedly expressed in all the IIM cases. Greater amounts of MCP-1 mRNA were observed in DM, and in situ hybridization showed MCP-1 mRNA accumulation in perivascular mononuclear cells. Immunohistochemistry showed MCP-1 expression in vessels (endothelial cells and walls of veins and arteries) in all IIM cases. Very few mononuclear cells in DM perivascular infiltrates expressed MCP-1, whereas in PM and IBM, it was strongly expressed by mononuclear cells partially invading non-necrotic muscle fibers. These findings suggest that MCP-1 can contribute to the inflammatory response by attracting monocytes and T lymphocytes to sites of cell-mediated immune injury. The morphological characteristics and distribution of positive cells indicate that macrophages, lymphocytes, and endothelial cells previously reported to produce MCP-1, contribute to its production in IIM lesions.

Exercise intolerance associated with myalgias, muscle cramps or myoglobinuria may be associated with a dystrophinopathy. A search for abnormal dystrophin expression (using immunohistochemistry, immunoblot and DNA analysis) was carried out in a series of 15 patients. They were selected because they presented exercise intolerance, negative biochemical tests (lipid, glycogen and mitochondrial metabolism) and abnormal immunohistochemistry with at least one anti-dystrophin antibody (anti-Dys 1, rod domain; anti-Dys 2, C terminus; anti-Dys 3, N terminus). Lack of anti-Dys 1 immunoreactivity was seen in three patients and abnormal immunoreactivity with all three anti-dystrophin antibodies in two. Immunoblot confirmed the dystrophinopathy in these five patients only, and multiplex polymerase chain reaction DNA analysis revealed a deletion in the dystrophin gene in two of these patients, affecting the proximal part of the rod domain in one and the distal part of this domain in the other. The clinical, biological and histopathological features of the five patients reported here, together with the previous cases reported in the literature, are described and reveal that exercise intolerance associated with dystrophinopathy displays characteristic clinical, biological and immunohistochemical features and defines a new dystrophinopathy phenotype. The absence of staining in the rod domain provides a secure diagnosis of this syndrome. Dystrophinopathy is one etiology of idiopathic myoglobinuria, requiring genetic counseling.

Clinicopathological, immunohistochemical and biochemical studies were performed on seven patients from five families showing an abnormal accumulation of desmin in the muscle fibers. Late onset myopathy was observed in all the cases studied. The clinical features were heterogeneous and usually nonspecific. However, some patients presented with dysphonia, dysphagia or cardiomyopathy. These features are highly suggestive of desmin myopathy. Using electron microscopy, desmin myopathy is characterized by an accumulation of granulofilamentous material. Depending on the distribution of the material, however, three different patterns of desmin accumulation can be observed: (1) large circumscribed inclusions, (2) intermyofibrillar areas of diffusely distributed material, and (3) deposits around large spheroid bodies. The second pattern is characterized by a rubbed-out appearance using oxidative enzyme reactions. For all the patients studied here, the immunohistochemical data showed that the desmin accumulation fitted these three patterns of distribution. For six patients, immunoblot analysis confirmed the desmin accumulation patterns and showed that an increase in the expression of the 53-kDa protein had occurred. The third pattern of desmin accumulation confirms the pathological heterogeneity of cytoplasmic and spheroid bodies. Desmin does not accumulate in all cytoplasmic and spheroid body myopathies, as observed in two other familial cases presented here.

CD24 is a glycoprotein with an unusual structure consisting of a small protein core extensively glycosylated and linked to the outer surface of the plasma membrane by a glycosylphosphatidylinositol (GPI) lipid anchor. Its murine homolog mCD24 is transiently expressed during the development and differentiation of the hematopoietic and neural cell lineages. We have searched for the expression of CD24 in the developing and in the mature human brain as well as in a wide range of neuroectodermal tumors. Neuroblastomas, a subgroup of tumors able to maturate from undifferentiated features towards mature ganglioneuromas, were more extensively studied. Immunohistochemical studies demonstrated that CD24 is transiently expressed by neurons during human brain development. In neuroectodermal tumors, CD24 is a marker of neuronal tumors. Furthermore, in neuroblastomas, CD24 expression decreases as tumors differentiate. In non-neuronal neuroectodermal tumors, CD24 expression is mostly absent. When present, it correlates with the emergence of anaplastic histological features. Reverse transcriptase -polymerase chain reaction (RT-PCR) demonstrated the presence of an unique transcript identical in both hematopoietic, developing and tumoral nervous tissue. RT-PCR and in situ hydridization techniques showed that CD24 expression is transcriptionally regulated. Interestingly, Western blot analysis demonstrated differential CD24 isoforms according to the tissue (hematopoietic versus nervous), the differentiation status, and the origin of neuroblastomas likely reflecting variations in the extent of glycosylation. This indicates an additional level of regulation of CD24 involving post-translational modifications.

A series of frozen specimens of 18 ependymomas and 7 choroid plexus tumors were examined for their expression of cell adhesion molecules, such as neural cell adhesion molecule (NCAM), its polysialylated isoforms (PSA NCAM), and epithelial (E-) cadherin, and of intermediate filament proteins, such as glial fibrillary acidic protein (GFAP) and cytokeratin, using various monoclonal and polyclonal antibodies. Normal choroid plexus and ependyma were taken as controls. Anti-E-cadherin immunoreactivity was observed on the basolateral part of most adult choroid plexus and benign choroid plexus papilloma cells. However, a small number of atypical papillomas and carcinoma cells showed anti- E-cadherin immunoreactivity throughout their cell surface membrane. NCAM were not expressed by adult choroid plexus and benign papilloma cells. Only a few cells expressed NCAM and PSA NCAM in developing choroid plexus, atypical papillomas and carcinomas. Cytokeratin expression was always observed in choroid plexus and their tumors; GFAP expression was variable from case to case. In contrast, ependymal cells and their tumors never expressed E-cadherin but strongly expressed NCAM. PSA NCAM was found in ependymomas exhibiting anaplastic features. All ependymomas strongly expressed GFAP and a few demonstrated slight expression of cytokeratin. These data suggest that, besides GFAP and cytokeratin, NCAM and E-cadherin are of potential diagnostic value in distinguishing choroid plexus tumors from ependymomas. E-cadherin and NCAM may play a role in the functional organization of normal choroid plexus and ependyma, respectively. In particular, incomplete or irregular anti-E-cadherin expression in choroid plexus tumors and PSA NCAM immunoreativity in ependymomas and choroid plexus tumors correlates with the emergence of anaplastic histological features.

Mechanisms of peripheral neuropathies in polyneuropathy, organomegaly, endocrinopathy, M-protein and skin changes (POEMS) syndrome are poorly understood. A peripheral nerve biopsy was performed in 22 patients. Of these 9 had histological features of Castleman's disease on lymph node biopsies, and 19 had a monoclonal lambda light chain in their serum. Certain nerve fragments were paraffin embedded, others were frozen and studied by direct immunofluorescence, and others were fixed for ultrastructural examination. Paraffin-embedded fragments did not show any amyloid deposits, and at direct immunofluorescence there was no immunoglobulin fixation. At ultrastructural examination, features of uncompacted myelin lamellae (UML) were present in 19 patients, and their frequency varied from 1% to 16% of myelinated fibres. Up to now UML have been reported only in 7 patients with POEMS syndrome in the literature. UML have also been noticed in a few cases of inflammatory demyelinating polyradiculoneuritis and inherited tendency to pressure palsy.

The expression of the CD24 molecule, a glycoprotein expressed at the surface of most B lymphocytes and differentiating neuroblasts, was studied in developing nerve and muscle (after 16 weeks of gestation), normal adult and various diseased human muscles using immunohistochemistry and Western blot analysis. Immunohistochemical studies demonstrated that: (1) in developing muscles, fibers did not express CD24, whereas only some mesenchymal areas, also expressing neural cell adhesion molecule (N.CAM) and vimentin, and developing nerves were positive; (2) in normal adult muscles, CD24 immunoreactivity was observed only in some unmyelinated nerve fibers--intra and extra fusal muscle fibers, satellite cells and neuromuscular junctions were negative; and (3) in all diseased muscles studied here, CD24 expression was always associated with a subpopulation of regenerative fibers. These fibers also expressed vimentin, desmin, developmental myosin heavy chain, N.CAM and its polysialylated isoforms (PSA-N.CAM). The number of CD24-positive fibers was always lower than that of PSA-N.CAM-positive fibers. Denervated fibers and vacuolated muscle fibers never expressed CD24. Western blot analysis indicated that the apparent molecular mass of CD24 antigen was different between muscle and developing nervous tissues, suggesting that CD24 glycosylation is tissue specific. Since the molecule was not expressed in developing human muscle fibers, it strongly suggests that regenerative and fetal myotubes are different with respect to the CD24 molecule expression.

We have examined pathological criteria in 16 cases of infratentorial ependymomas of childhood using a conventional histological approach, with immunohistochemistry and silver nucleolar organizer region staining (AgNORs). We have found that some of these criteria are of prognostic value. The following histological features were evaluated in each case: cellular density, cellular or nuclear pleiomorphism, mitosis, focal necrosis, endothelial proliferation and complete loss of differentiation. The expression of the following antigens was also studied: epithelial membrane antigen (EMA), human natural killer (HNK1), glial fibrillary acidic protein (GFAP) and vimentin. Only three histological criteria have been retained as indicative of bad prognosis, i.e., high mitotic index, a large amount of necrosis and complete loss of differentiation. These criteria distinguish ependymomas from anaplastic ependymomas. GFAP was expressed in all tumors while other antigens were more variable. In addition tumors expressing large amounts of GFAP were statistically associated with a better prognosis. Increased vimentin expression associated with a decrease of GFAP immunoreactivity correlated with anaplasia and short survival. EMA was not directly correlated with postoperative survival but may be considered as a further prognostic factor. Finally AgNORs values were not statistically correlated with postoperative survival.

In ten patients with inclusion body myositis (IBM) five muscular biopsies showed profuse inflammatory exudates and three showed a few scattered inflammatory cells with partial invasion in some muscle fibers. No inflammatory cells were seen in two cases. In all patients, histopathological, histomorphometric and immunocytochemical studies were performed. Immunocytochemistry for the class I and class II major histocompatibility complex gene product (MHC) was performed in all cases and in ten control muscles including: normal muscles [3], dermatomyositis [3], polymyositis [3], scleroderma [1]. In the five cases of IBM with inflammatory exudates, subsets of lymphocytes were analyzed with a panel of monoclonal antibodies against B cells, T4 cells, T8 cells, K and natural killer cells and macrophages. Some muscle fibers expressed class I MHC antigens in the inflammatory cases of IBM. These fibers were near the inflammatory exudates and occasionally showed a partial invasion. No expression of class I MHC was found in normal muscles and in non-inflammatory cases of IBM. The antigen which triggers the mononuclear cells in the inflammatory forms of IBM is probably not the filamentous inclusions in rimmed vacuoles. In other inflammatory myopathies, expression of class I MHC was present on all fibers in polymyositis, only in the perifascicular area in dermatomyositis and in scleroderma. It could be suggested that the term "inclusion body muscle disease" be applied to cases with rimmed vacuoles and "IBM-like" filaments without inflammatory cells.

The authors report electron microscopic findings in brain, bone marrow and liver biopsies in a case of juvenile Niemann-Pick disease (Crocker's type C). The diagnosis was supported by clinical data increase of blood sphingomyelin and vacuolated histiocytes in bone marrow and liver. Neurons and glial cells were filled with two types of cytosomes: classical multilamellar bodies and unusual pleiomorphic bodies. The latter type probably showed some lipofuscinic component. The relationship between type C and classical Niemann-Pick disease is discussed.

A case of giant axonal neuropathy in a 8 years old child is reported by light and electron microscopy. Clinically, this case is strikingly similar to the rare previous reports and characterized by a distal neuropathy, CNS symptoms and tightly curled hair. Giant axons were found in the sural nerve but had been absent at the onset of the illness. An increase in the number of neurofilaments was found in the axons and neurons of the myenteric plexus. The number of microfilaments was also increased in various types of cells namely Schwann and endothelial cells and fibroblasts: This suggests that the metabolic disorder, probably inborn and genetic, does not only affect the nervous system.

Two siblings born from consanguineous tunisian parents are reported. They showed a severe form of Farber's disease with prominent involvement of the central and peripheral nervous system: low conduction velocity was noticed in both children. Macular cherry red spots were observed in one of them. The diagnosis for the girl investigated was confirmed by evidence of ceramidase deficiency in cultured fibroblasts. Here we report the pathological findings in the subcutaneous nodules using light and electron microscopy (one case), and in sural nerves using morphometric studies (both cases). Varying morphological aspects of intracellular inclusions, depending on the tissues involved, are described and discussed. A review of all cases reported since Farber's first paper in 1952 is given.