Gene/Protein Disease Symptom Drug Enzyme Compound
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Query: UMLS:C0027121 (myositis)
 4,538 document(s) hit in 31,850,051 MEDLINE articles (0.00 seconds)

Muscle biopsy specimens from 15 autopsied patients with the isolated form of amyotrophic lateral sclerosis were examined by routine histological and immunocytochemical methods using a panel of monoclonal antibodies directed against differentiation and activation markers of immunocompetent cells. In 12 cases, cellular infiltrates consisting mainly of T-cells and macrophages were seen. Both CD8+ and CD3+ cells, in juxtaposition with OKM1+ macrophages, were particularly seen in the atrophied parts of muscle. The majority of the T-cells appeared to be of the CD4+ T-helper/inducer type, whereas the CD8+ T-suppressor/cytotoxic cells were only rarely and focally present. On the other hand, B-, NK- and K-cells were infrequently seen. Most of the T-cells and macrophages surrounding the atrophied muscle fibers were in an activated state, as indicated by their intense HLA DR expression. In addition, some angulated degenerated fibers showed strong endomysial positivity for HLA DR in the regions where T-cells and macrophages were present in clusters. The immunoreactive changes in ALS-associated muscle atrophy are very similar to those reported for exercise-induced damage and some forms of myositis. The present study shows that the expression of major histocompatibility complex products and the relative numbers of infiltrating immunocompetent cells are closely associated with the extent of destruction of muscle fibers in ALS.
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PMID:Immunohistological alterations in muscle of patients with amyotrophic lateral sclerosis: mononuclear cell phenotypes and expression of MHC products. 161 23

To investigate the pathological mechanisms of polymyositis, we performed immunohistochemical analyses with biopsied muscles. Comparative studies using specimens obtained from the same patient enabled us to analyze the pathological alterations at different sequential clinical phases without taking into account each immunogenetic difference. Expression of MHC (major histocompatibility complex) antigens, especially ectopic MHC-class-II antigens, in muscle fibers and infiltrating T-cells were shown to increase concomitantly with the clinically observed exacerbation. Moreover, other observations seem to support the possibilities that 1) administration of steroids lowers the number of invading CD8-positive cells, 2) induction of MHC-class-I antigens in muscle fibers precedes the inflammatory cell infiltration and that 3) remaining MHC-class-I antigens in muscle fibers may explain the recurrence of myositis often observed in the follow up period.
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PMID:Temporal alterations of immunohistochemical findings in polymyositis. 794 28

Advances in molecular biologic techniques and the availability of novel immunologic reagents have allowed new approaches to understanding the pathogenesis of human autoimmune diseases, including the idiopathic inflammatory myopathies. Indirect evidence that autoreactive T cells mediate muscle inflammation in the human myositis syndromes has been strengthened by recent studies describing restricted T cell receptor gene expression in certain clinical and/or serologic groups of myositis patients. These findings are supported by other investigations documenting abnormal patterns of cytokine, adhesion molecule, and major histocompatibility complex antigen expression within inflammatory lesions. The major challenge of future studies is to identify the specific antigen(s) responsible for initiating and perpetuating these harmful immune responses.
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PMID:T cell-mediated immune mechanisms in myositis. 857 70

Genetic predisposition to development of the idiopathic inflammatory myopathies is probably multifactorial. Major histocompatibility complex associations with these diseases provide the strongest evidence for a genetic component. In Caucasoids, haplotypes marked by B8/DR3 are associated with each of the clinical subgroups, except mixed connective tissue disease (DR4). The strongest associations are with inclusion body myositis, polymyositis in the presence of anti-Jo-1, and with antibodies to PM-Scl in overlap syndromes. The underlying mechanisms of these associations are probably different. Unique major histocompatibility complex associations are seen with other myositis-associated autoantibodies. The association can vary between racial groups as can the type of autoantibody produced within a disease subgroup, perhaps reflecting different T cell receptor repertoires or different inducing agents. The mapping of a gene for one form of hereditary inclusion body myositis to chromosome 9p1-q1 provides a lead for the investigation of sporadic inclusion body myositis, as does the expanding knowledge of genetic factors in Alzheimer's disease. The demonstration of deletions of mitochondrial DNA in the muscle of patients with inclusion body myositis raises the question of their role in the pathogenesis of the disease.
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PMID:Genetics of the idiopathic inflammatory myopathies. 901 54

In 14 patients with polymyositis (PM), 5 patients (2 males and 3 females) were positive for anti-hepatitis C virus (HCV) antibody measured by a second generation assay. We analysed the clinical characteristics and histopathological findings of the biopsied muscles from those 5 patients. They aged from 42 to 65 years averaging 53.6 years. Two asymptomatic patients visited our hospital due to elevated muscle enzyme levels, who had slight weakness in their orbicularis oculi and neck muscles on physical examination. The other 3 patients had moderate weakness of the proximal muscles. Anti-nuclear antibody was positive in 2 of the 5 patients and anti-Jo 1 antibody was negative in all patients. The serum enzymes elevated were creatine kinase (215-2, 207 (IU/l)) and glutamate oxaloacetate transaminase (40-119 (KU)). HCV-RNA was positive in the sera of 4 patients examined. All muscle biopsy specimens revealed variation in fiber size with inflammatory cellular infiltration and observed degenerating and regenerating fibers. The scant infiltration type was observed in 2 asymptomatic patients in whom the infiltrated cells were CD4 positive. The endomysial infiltration type was observed in 3 symptomatic patients; CD8 positive cells were found focally to diffusely in 2 patients examined. The expression of class 1 molecules from the major histocompatibility complex was detected mainly in infiltrated fibers to variable degrees. All of the patients showed a good response to the initial steroid therapy. The present study suggests that autoimmune reaction related to HCV infection causes myositis, therefore anti-HCV antibody should be checked in cases of PM.
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PMID:[Clinical characteristics and muscle histopathology in polymyositis positive anti-hepatitis with C virus antibody]. 921 18

The idiopathic inflammatory myopathies (IIMs) encompass a group of muscle disorders of unknown origin and pathogenesis characterized by symmetrical, proximal muscle weakness and by inflammatory infiltrates in muscle tissue. The mechanisms behind the loss of muscle function are largely unknown. It is often anticipated that the muscle weakness is caused by the inflammatory cells. However, inflammatory infiltrates are not always present in the muscle tissue and the infiltrates sometimes have a patchy distribution, which makes it difficult to explain the generalized muscle weakness merely by infiltration of inflammatory cells. We investigated patients at different stages of myositis: early myositis without detectable inflammatory infiltrates, active myositis with pronounced inflammatory infiltrates and chronic myositis with persisting muscle weakness but without detectable inflammatory cells in muscle tissues. In these studies, a better correlation was observed between the clinical symptoms and involvement of the capillaries with expression of the cytokine interleukin (IL)-1alpha and by the presence of major histocompatibility complex (MHC) class I expression on muscle fibres. Whether these molecules could affect muscle function is not known. Using phosphorus P-31 magnetic resonance spectroscopy decreased values of adenosine triphosphate (ATP) and phosphocreatine (PCr) levels were observed at rest. These metabolic abnormalities were further accentuated by exercise and increased PCr levels correlated with improved clinical status. The underlying mechanisms responsible for these biochemical abnormalities have not been defined but could be related to a disturbed tissue oxygenation.
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PMID:The physiology of inflammatory myopathies: an overview. 1141 32

The aim of our study was to address the question of whether muscle fibers express major histocompatibility complex (MHC) class II in inflammatory myopathies. For this purpose we performed a systematic study of MHC class II antigen expression on muscle fiber membranes in muscle tissue from polymyositis and dermatomyositis patients in various stages of disease activity. Thirty-two patients with classical clinical signs of myositis were divided into subgroups depending on duration of clinical signs of myositis and presence or absence of inflammatory infiltrates in muscle tissue. Immunohistochemistry as well as double-immunofluorescence stainings were used to identify the presence of MHC class II in muscle tissue. MHC class I was included for comparison. Quantification of positive staining was performed using an image analysis system in addition to evaluation by manual microscopic scoring and laser confocal microscopy. It was demonstrated that a significant proportion of skeletal muscle fibers in inflammatory myopathies express MHC class II as well as MHC class I and that MHC antigen expression is independent of the inflammatory cell infiltration. Furthermore, there were no differences in staining pattern between polymyositis and dermatomyositis patients. Our results indicate that MHC class II and MHC class I molecules may be involved in initiating and maintaining the pathological condition in myositis rather than only being a consequence of a preceding local inflammation.
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PMID:Skeletal muscle fibers express major histocompatibility complex class II antigens independently of inflammatory infiltrates in inflammatory myopathies. 1158 54

A 7-year-old female Labrador Retriever dog showed extreme muscular weakness, muscle wasting, dysbasia, and mild dysphagia. An elevated value of creatine kinase (335 IU/liter) in the serum was detected. Electromyographic findings included increased insertional activity, fibrillation potentials, and bizarre high-frequency repetitive potentials. Histopathologic examination of skeletal muscles revealed myofiber necrosis and phagocytosis, regeneration of myofibers, and perivascular, perimysial, and endomysial infiltrations of lymphocytes, macrophages and plasma cells. Immunohistochemical evaluation demonstrated that infiltrative cells in the early stage of myositis were CD8+ T-cells and that an increased expression of major histocompatibility complex (MHC) class I was apparent on the surface of nonnecrotic muscle fibers. In contrast, many CD3+ cells (T cells) and HLA-DR-positive macrophages and B lymphocytes were found in the severely affected areas. These results suggest that both expression of MHC class I and CD8+ T-cell infiltration may play an important role in initiation of myositis. These histopathologic findings resemble those reported in naturally occurring polymyositis in humans.
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PMID:Myofiber expression of class I major histocompatibility complex accompanied by CD8+ T-cell-associated myofiber injury in a case of canine polymyositis. 1212 58

We report a case of myositis associated with chronic hepatitis C virus infection. Muscle biopsy and immunohistochemistry showed perifascicular atrophy, few necrotic and regenerating fibres, scarce perivascular infiltrates, deposits of immunoglobulin G, C3, fibrinogen and MAC in muscle vessel walls, and non-uniform expression of major histocompatibility complex-I antigens among muscle fibres. Hepatitis C virus NS3 antigen and hepatitis C virus RNA were detected in infiltrating cells but not within muscle fibres or endothelial cells. Our findings suggest that humoral-mediated immune mechanisms, not directly related to hepatitis C virus infection of muscle structures, may sustain the local inflammatory reaction in this patient.
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PMID:Hepatitis C virus infection and myositis: a virus localization study. 1246 35

Muscle inflammation is characteristic of inflammatory myopathies but also occurs in muscular dystrophy with lack of the sarcolemmal protein dysferlin. We quantified inflammatory cells and major histocompatibility complex (MHC) expression in muscle from 10 patients with dysferlinopathy. Infiltrating cells were always present although numbers varied considerably; macrophages were more common than T cells, T cytotoxicity was absent, and MHC class I was overexpressed on muscle fibers. These findings differ from polymyositis (PM) but are closely similar to those in SJL/J mice (which lack dysferlin) and emphasize the relationship between absence of dysferlin and immune system abnormalities in muscle.
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PMID:Muscle inflammation and MHC class I up-regulation in muscular dystrophy with lack of dysferlin: an immunopathological study. 1451 71


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