Gene/Protein Disease Symptom Drug Enzyme Compound
Pivot Concepts:   Target Concepts:
Query: UMLS:C0011633 (dermatomyositis)
 4,181 document(s) hit in 31,850,051 MEDLINE articles (0.00 seconds)

Polymyositis and dermatomyositis are inflammatory myopathies characterized by proximal muscle weakness and myopathic electromyographic and histological findings. While the causes of myositis are not known, the close association of these disorders with a spectrum of autoantibodies suggests an etiologic and/or pathogenetic role for autoimmune processes. Of particular interest in this regard are antibodies directed against histidyl as well as other tRNA synthetases which are almost uniquely associated with myositis and may define a distinct subset of patients. Recently we isolated the histidyl tRNA synthetase gene which encodes the autoantigen representing the most frequent target of the myositis autoimmune response. The isolation and expression of this gene has allowed us to investigate both the autoreactive epitopes on histidyl-tRNA synthetase and the extent to which these correlate with functional epitopes on the molecule. As described here, the results of these studies as well as other recent data pertaining to the immunopathogenesis of myositis, provide a framework for delineating the mechanisms which render synthetases and other translation-related proteins autoantigenic in myositis, and allow one to examine the significance of such autoimmune responses in the etiology and pathogenesis of inflammatory myopathy.
 ...
PMID:Anti-Jo-1 autoantibodies and the immunopathogenesis of autoimmune myositis. 172 33

We studied the immunologic correlates of disease activity and differences among subgroups of patients with idiopathic inflammatory myopathy by analysing phenotypic and activation marker expression on peripheral blood mononuclear cells (PBMC). Compared with controls, myositis patients with clinically active disease (n = 51) had significantly lower proportions of CD8+ cells and higher proportions of PBMC that expressed DR, CD3- DR, CD14- DR, interleukin-2 receptors, and the late T cell activation markers CD26 and TLiSA1. TLiSA1 expression, a marker for cytotoxic differentiation, correlated significantly with both clinical activity indices and serum levels of muscle-associated enzymes. In serial studies of seven patients, the proportion of PBMC expressing MHC class II antigen and late T cell activation markers decreased as myositis disease activity decreased, independent of type of therapy. Among the clinical subgroups, polymyositis (n = 21) and inclusion body myositis (n = 11) were virtually indistinguishable; dermatomyositis patients (n = 19) showed decreased proportions of CD3+DR+ and TLiSA1+ cells, and increased proportions of CD20+ and CD20+DR+ cells compared with the other two groups. Patients with autoantibodies to histidyl-tRNA synthetase (Jo-1 antigen, n = 11) had significantly lower proportions of CD3+ and CD4+ cells, lower CD4/CD8 ratios, and higher proportions of CD+ cells expressing CD20, compared with patients without anti-Jo-1 antibodies. These findings support the concept that activated lymphocytes, especially cells undergoing anamnestic responses and cytotoxic differentiation, are important in the pathogenesis of idiopathic myositis. Moreover, taken together with other studies, these data suggest that groups of patients segregated by clinical or autoantibody status have different mechanisms of systemic immune activation and immunopathology.
 ...
PMID:Lymphocyte activation markers in idiopathic myositis: changes with disease activity and differences among clinical and autoantibody subgroups. 216 21

Autoantibodies that bind aminoacyl-tRNA synthetases are strongly associated with the human inflammatory myopathies polymyositis and dermatomyositis, but their molecular origins and relationship to pathogenesis are not known. To address these issues, we wished to identify the autoantigenic epitopes which react with these autoantibodies and to this end, we previously isolated a full length cDNA clone encoding the target Ag recognized most frequently by myositis sera, histidyl-tRNA synthetase (HRS). In the present study, we have analyzed the HRS autoepitopes by two amino acid insertion linker mutagenesis of HRS proteins expressed in Cos 1 cells. A series of mutant HRS cDNA were constructed and the expressed proteins were tested for enzyme activity and for immune reactivity with a panel of sera with anti-Jo-1 antibodies. Immunoblotting and immunoprecipitation analyses revealed that anti-Jo-1 antibodies recognize multiple conformation-dependent and independent epitopes on HRS and that the autoepitopes vary among different myositis patients.
 ...
PMID:Epitope mapping of the cloned human autoantigen, histidyl-tRNA synthetase. Analysis of the myositis-associated anti-Jo-1 autoimmune response. 247 3

The increased detection of anti-Jo-1 antibody afforded by the use of the purified antigen, histidyl-tRNA synthetase, in counterimmunoelectrophoresis is demonstrated. Using purified antigen, anti-Jo-1 antibody was detected in the sera of 16/33 (48.5%) patients with confirmed myositis and in 20/45 (44.5%) patients with confirmed or possible myositis. This rate is approximately double that obtained with commercial thymus extracts both in this study and seven others reported in the literature. The presence of antibody shows marked correlation with the activity of myositis at the time of serum sampling and with the presence of interstitial lung disease. Detection rates are similar in patients with polymyositis and dermatomyositis both with and without additional connective tissue diseases.
 ...
PMID:Improved detection of anti-Jo-1 antibody, a marker for myositis, using purified histidyl-tRNA synthetase. 310 Jun 49

We have developed an enzyme-linked immunosorbent assay (ELISA) specific for autoantibodies directed against the autoantigen Jo-1 (histidyl-tRNA synthetase) using antigen prepared biochemically from HeLa cells. No other patient sera, including those containing antibodies directed at threonyl-tRNA synthetase or alanyl-tRNA synthetase, reacted in the assay. Screening of sera from 169 patients with a variety of autoimmune and neuromuscular diseases confirmed that anti-Jo-1 antibodies are confined to a subgroup of patients with pure polymyositis, pure dermatomyositis, or myositis associated with another rheumatic disease.
 ...
PMID:An enzyme-linked immunosorbent assay for the detection and quantitation of anti-Jo-1 antibody in human serum. 349 84

Autoantibodies are found in most patients with polymyositis (PM) or dermatomyositis (DM) and 35-40% of these patients have myositis-specific antibodies. Twenty-five to thirty percent have anti-aminoacyl-tRNA synthetases, of which anti-Jo-1, directed at histidyl-tRNA synthetase, is by far the most common. Patients with anti-synthetases have a high frequency of myositis, interstitial lung disease, Raynaud's phenomenon, and other features constituting an "anti-synthetase syndrome." Anti-synthetases tend to react with conformational epitopes and to inhibit enzymatic activity, suggesting reaction with conserved regions. Sera with antibodies to alanyl-tRNA synthetase (anti-PL-12) also have antibodies to tRNA(ala), whereas most sera with other anti-synthetases do not react directly with tRNA. Production of the antibodies appears to be antigen-driven, and is influenced by HLA genes, although an initiating factor, possibly a viral infection, may be important. Antibodies to other cytoplasmic antigens, most notably the signal recognition particle (anti-SRP), are seen in a small percentage of patients. Patients with anti-SRP do not tend to develop the anti-synthetase syndrome, but may have very severe disease. Antibodies to the nuclear antigen Mi-2 are also specific for myositis, and are strongly associated with DM. Several autoantibodies, including anti-PM-Scl, anti-Ku, and anti-U1 and U2 RNP, have been associated with scleroderma-PM overlap. The role of humoral immunity in the myositis of PM and DM has not yet been clarified. Capillary loss and ischemic damage are important in DM, and seem to be mediated by humoral mechanisms, whereas cell-mediated attack on muscle fibers is important in PM. The mechanism of skin injury in cutaneous lesions is not known, but antibody deposition is inconsistent and uncommon. Whether the myositis-specific antibodies are involved in disease pathogenesis is not yet known, although there is no direct evidence for this. An understanding of the reasons for production of these antibodies, however, should provide insight into the etiology and pathogenesis of PM and DM.
 ...
PMID:Humoral immunity in polymyositis/dermatomyositis. 842 80

We report an interesting association of inflammatory myopathy, characterized pathologically as dermatomyositis, with bronchiolitis obliterans/organizing pneumonia and anti-histidyl-tRNA synthetase (Jo-1) antibody. The relations of different types of pulmonary involvement to inflammatory myopathy and antisynthetase antibodies are discussed.
 ...
PMID:Inflammatory myopathy, bronchiolitis obliterans/organizing pneumonia, and anti-Jo-1 antibodies--an interesting association. 906 64

The most common scleroderma overlap syndromes are mixed connective tissue disease (MCTD), scleromyositis and synthetase syndrome. There is controversy concerning MCTD as a separate entity due to heterogeneous clinical manifestations, not infrequent transformation into definite CTD and various classification criteria. Our study of 94 adult patients and 20 children, classified according to the criteria of Alarcon-Segovia, and especially a 5, 9-year follow-up showed transformation into SLE or SSc in over 20% of patients, less frequently than reported by others, whereas over half of the cases remained undifferentiated CTD. In several cases ARA criteria for both SSc and SLE were fulfilled, and there is no consensus whether such cases should be recognized as coexistence of both definite diseases or as MCTD. High titers of U1 RNP antibodies to 70 kD epitope were invariably present, whereas, by transformation into distinctive CTD there appeared, in addition, antibodies characteristic of these CTD. Of 108 cases positive for PM-Scl antibody, 83% were associated with scleromyositis. This scleroderma overlap syndrome differed from MCTD by coexistent features of dermatomyositis (myalgia, myositis, Gottron sign, heliotrope rash, calcinosis) with no component of SLE, characteristic of MCTD. The course was also chronic and rather benign, as in MCTD, and all cases responded to low or moderate doses of corticosteroids. A not infrequent complication was deforming arthritis of the hands. Our immunogenetic study showed an association of cases positive for PM-Scl antibody with HLA-DQA1x0501 alleles in 100% and with HLA-DRB1x0301 in 94% of cases. Synthetase syndrome, associated with anti-histidyl-tRNA synthetase antibodies, studied in 29 patients with myositis and interstitial lung disease (ILD), only in single cases had scleroderma-like features. These cases differed from SSc by acute onset with fever, and by response to moderate doses of corticosteroids. We also studied overlap of localized scleroderma with other CTD: 21 cases of progressive facial hemiatrophy and linear scleroderma, and 55 (39.5%) of atrophoderma Pasini-Pierini (APP) and morphea. As in other autoimmune disorders, two or more connective tissue diseases (CTD) may develop concurrently or sequentially in the same patient. In such overlap syndromes ARA criteria must be fulfilled for each of the disease, and the clinical presentation has features of both. However more frequently overlap syndromes only combine some manifestations of more than one CTD, and present a highly heterogeneous group of disorders with prevailing clinical features of SSc.
 ...
PMID:Scleroderma overlap syndromes. 1059 27

In the human inflammatory myopathies (polymyositis and dermatomyositis), the early, widespread appearance of MHC class I on the surface of muscle cells and the occurrence of certain myositis-specific autoantibodies are striking features. We have used a controllable muscle-specific promoter system to up-regulate MHC class I in the skeletal muscles of young mice. These mice develop clinical, biochemical, histological, and immunological features very similar to human myositis. The disease is inflammatory, limited to skeletal muscles, self-sustaining, more severe in females, and often accompanied by autoantibodies, including, in some mice, autoantibodies to histidyl-tRNA synthetase, the most common specificity found in the spontaneous human disease, anti-Jo-1. This model suggests that an autoimmune disease may unfold in a highly specific pattern as the consequence of an apparently nonspecific event-the sustained up-regulation of MHC class I in a tissue-and that the specificity of the autoantibodies derives not from the specificity of the stimulus, but from the context, location, and probably the duration of the stimulus. This model further suggests that the presumed order of events as an autoimmune disease develops needs to be reconsidered.
 ...
PMID:Conditional up-regulation of MHC class I in skeletal muscle leads to self-sustaining autoimmune myositis and myositis-specific autoantibodies. 1092 29

Autoantibodies to histidyl-tRNA synthetase (HisRS) or to alanyl-, asparaginyl-, glycyl-, isoleucyl-, or threonyl-tRNA synthetase occur in approximately 25% of patients with polymyositis or dermatomyositis. We tested the ability of several aminoacyl-tRNA synthetases to induce leukocyte migration. HisRS induced CD4(+) and CD8(+) lymphocytes, interleukin (IL)-2-activated monocytes, and immature dendritic cells (iDCs) to migrate, but not neutrophils, mature DCs, or unstimulated monocytes. An NH(2)-terminal domain, 1-48 HisRS, was chemotactic for lymphocytes and activated monocytes, whereas a deletion mutant, HisRS-M, was inactive. HisRS selectively activated CC chemokine receptor (CCR)5-transfected HEK-293 cells, inducing migration by interacting with extracellular domain three. Furthermore, monoclonal anti-CCR5 blocked HisRS-induced chemotaxis and conversely, HisRS blocked anti-CCR5 binding. Asparaginyl-tRNA synthetase induced migration of lymphocytes, activated monocytes, iDCs, and CCR3-transfected HEK-293 cells. Seryl-tRNA synthetase induced migration of CCR3-transfected cells but not iDCs. Nonautoantigenic aspartyl-tRNA and lysyl-tRNA synthetases were not chemotactic. Thus, autoantigenic aminoacyl-tRNA synthetases, perhaps liberated from damaged muscle cells, may perpetuate the development of myositis by recruiting mononuclear cells that induce innate and adaptive immune responses. Therefore, the selection of a self-molecule as a target for an autoantibody response may be a consequence of the proinflammatory properties of the molecule itself.
 ...
PMID:Histidyl-tRNA synthetase and asparaginyl-tRNA synthetase, autoantigens in myositis, activate chemokine receptors on T lymphocytes and immature dendritic cells. 1223 11


1 2 Next >>