References

1. Hengstman GJ, Brouwer R, Egberts WT, Seelig HP, Jongen PJ, van Venrooij WJ, van Engelen BG. Clinical and serological characteristics of 125 Dutch myositis patients. Myositis specific autoantibodies aid in the differential diagnosis of the idiopathic inflammatory myopathies. J Neurol. 2002 Jan;249(1):69-75. PMID:11954871.

Abstract

The idiopathic inflammatory myopathies (IIM) are a heterogeneous group of systemic diseases that include the familiar disease entities of dermatomyositis (DM), polymyositis (PM), and inclusion body myositis (IBM). A subset of patients has unique autoantibodies which are specific for IIM (myositis specific autoantibodies; MSAs). We studied the clinical and serological characteristics of IIM in 125 Dutch patients. Sera were analysed by immunoblotting, enzyme-linked immunosorbent assay, and immunoprecipitation. The most frequently encountered MSA was the anti-Jo-1 autoantibody (20%), followed by anti-tRNAHis (6%), anti-Mi-2 (6%), and anti-SRP (4%). The presence of certain MSAs was clearly associated with specific clinical characteristics. Anti-Jo-1 and anti-tRNAHis were associated with the anti-synthetase syndrome, anti-SRP with PM with severe myalgia and arthralgia and a moderate response to immunosuppressive treatment. A novel finding was the presence of anti-Mi-2, not only in DM, but also in PM. MSAs were frequently present in DM/PM sera, but were hardly ever detected in the sera of IBM patients. The few IBM patients with MSAs demonstrated a significant response to immunosuppressive treatment. It can be concluded that MSAs define specific clinical syndromes within the spectrum of IIM and that they can assist in the differential diagnosis and treatment plan of these enigmatic disorders by virtually excluding IBM by their presence, and by potentially identifying a subgroup of steroid-responsive IBM patients.

​——————————————————————–

2. Bronner IM, van der Meulen MF, de Visser M, Kalmijn S, van Venrooij WJ, Voskuyl AE, Dinant HJ, Linssen WH, Wokke JH, Hoogendijk JE. Long-term outcome in polymyositis and dermatomyositis. Ann Rheum Dis. 2006 Nov;65(11):1456-61. Epub 2006 Apr 10. PMID:16606652.

Abstract

BACKGROUND: Although polymyositis and dermatomyositis are regarded as treatable disorders, prognosis is not well known, as in the literature long-term outcome and prognostic factors vary widely. Aim: To analyse the prognostic outcome factors in polymyositis and adult dermatomyositis. METHODS: We determined mortality, clinical outcome (muscle strength, disability, persistent use of drugs and quality of life) and disease course and analysed prognostic outcome factors. RESULTS: Disease-related death occurred in at least 10% of the patients, mainly because of associated cancer and pulmonary complications. Re-examination of 110 patients after a median follow-up of 5 years showed that 20% remained in remission and were off drugs, whereas 80% had a polycyclic or chronic continuous course. The cumulative risk of incident connective tissue disorder in patients with myositis was significantly increased. 65% of the patients had normal strength at follow-up, 34% had no or slight disability, and 16% had normal physical sickness impact profile scores. Muscle weakness was associated with higher age (odds ratio (OR) 3.6; 95% confidence interval (CI) 1.3 to 10.3). Disability was associated with male sex (OR 3.1; 95% CI 1.2 to 7.9). 41% of the patients with a favourable clinical outcome were still using drugs. Jo-1 antibodies predicted the persistent use of drugs (OR 4.4, 95% CI 1.3 to 15.0). CONCLUSIONS: Dermatomyositis and polymyositis are serious diseases with a disease-related mortality of at least 10%. In the long term, myositis has a major effect on perceived disability and quality of life, despite the regained muscle strength.

​——————————————————————–

3. Targoff IN, Miller FW, Medsger TA Jr, Oddis CV.Classification criteria for the idiopathic inflammatory myopathies. Curr Opin Rheumatol. 1997 Nov;9(6):527-35. PMID:9375282.

​Abstract

As the clinical features of the idiopathic inflammatory myopathies are not easily differentiated from those of other similar rheumatic and neurologic conditions, diagnosis is often difficult. Various classification criteria for polymyositis and dermatomyositis have been suggested by a number of investigators. The most commonly accepted and used criteria include symmetric proximal muscle weakness, serum elevations of muscle enzymes, the classic electromyographic and muscle biopsy findings of inflammatory myopathy, and the typical skin rash of dermatomyositis. Although these criteria are clinically useful, they can result in misdiagnoses and inappropriate therapies. They also result in heterogeneous patient groups being selected for clinical and laboratory studies. Furthermore, they do not include recent findings related to the myositis-specific autoantibodies and magnetic resonance imaging of muscle that have been found to be important adjuncts in assessing patients with muscle weakness or elevations of muscle enzymes. A modification to the Bohan and Peter criteria is proposed to include myositis-specific autoantibodies and magnetic resonance imaging. This proposal could initiate productive discussions and investigations of the sensitivity and specificity of new classification criteria for myositis and could ultimately enhance our treatment capabilities.

​​——————————————————————–

4. Hengstman GJ, van Engelen BG, van Venrooij WJ. Myositis specific autoantibodies: changing insights in pathophysiology and clinical associations. Curr Opin Rheumatol. 2004 Nov;16(6):692-9. PMID:15577606.

Abstract

PURPOSE OF REVIEW: Defined autoantibodies are found in about half of the patients with myositis. Traditionally, these autoantibodies have been divided into myositis specific autoantibodies (MSAs) and myositis associated autoantibodies. Several studies have shown that MSAs are associated with specific clinical characteristics and can aid our understanding of the pathophysiology of myositis. RECENT FINDINGS: Recent studies suggest that some MSAs are markers of specific inflammatory muscle diseases (e.g., anti-SRP for an immune-mediated necrotizing myopathy) and not just of myositis in general. Furthermore, new insights are emerging about the pathophysiology of MSAs, in particular anti-Jo-1. Based on these new insights, an alternative hypothesis of the formation of anti-Jo-1 autoantibodies is presented in which the immune system itself rather than muscle is the site of antigen presentation. SUMMARY: The recognition that some MSAs are markers of specific disease entities that were once commonly referred to as (poly)myositis, aids the development of better disease definitions. The changing insights in the function of the Jo-1 antigen and the emergence of new hypotheses on the formation of the Jo-1 antibody, open new avenues for future research aimed at unraveling the mystery of myositis.

​​——————————————————————–

5. Stuhlmüller B, Jerez R, Hausdorf G, Barthel HR, Meurer M, Genth E, Kalden JR, Burmester GR. Novel autoantibodies against muscle-cell membrane proteins in patients with myositis. Arthritis Rheum. 1996 Nov;39(11):1860-8. PMID:8912508.

​Pdf-file not avaliable

​Abstract

OBJECTIVE: To search for autoantibodies against muscle cell-specific surface membrane antigens in patients with inflammatory myopathies.

METHODS: A cell enzyme-linked immunosorbent assay (cell ELISA) using a human rhabdomyosarcoma cell line (TE-671) was developed and performed in serial dilutions with either nonfixed or fixed cells. A total of 141 different patient sera were tested: 90 from patients with various rheumatic diseases, 12 from patients with cardiomyopathies, 25 from patients with other muscular diseases, and 14 from patients who had undergone major surgery or who had other noninflammatory diseases. As controls, 20 sera were obtained from healthy donors. Results were correlated using immunofluorescence staining and flow cytometry.

RESULTS: Using the nonfixed cell ELISA, the proportions of positive sera from the patient groups with rheumatic diseases were 71% with polymyositis (PM), 15% with dermatomyositis (DM), 18% with systemic sclerosis (SSc), 15% with systemic lupus erythematosus (SLE), and 7% with rheumatoid arthritis. Sera from healthy donors, as well as sera from patients with nonrheumatic diseases, did not show significant reactivities. When other cell lines, including a chondrosarcoma, a bladder carcinoma, a pancreas carcinoma, and human foreskin fibroblasts, were used as substrates, positive sera did not react in the cell ELISA. Results obtained with the cell ELISA system using nonfixed cells were confirmed by flow cytometry and immunofluorescence staining. A strong protein band of 50 kd was detected on plasma membrane preparations from TE-671 muscle cells in 33% of PM sera (n = 12).

CONCLUSION: In most sera from patients with PM, DM, and some other rheumatic diseases (i.e., SSc and SLE), autoantibodies directed against muscle-cell surface antigens can be detected. Since these molecules are localized in the muscle-cell surface membrane, autoantibodies directed against these antigens could play a major role in the pathogenesis of PM.

​​——————————————————————–

6. Targoff IN. Update on myositis-specific and myositis-associated autoantibodies. Curr Opin Rheumatol. 2000 Nov;12(6):475-81. PMID:11092195.

Abstract

Myositis-specific autoantibodies or myositis-associated autoantibodies can often be found in serum of patients with polymyositis and dermatomyositis. The presence of these autoantibodies can be significant in patient diagnosis and classification. Recent studies have provided new information about many of these specific autoantibodies. Among the more important developments were identification of a new antisynthetase, reacting with asparaginyl-tRNA synthetase; the detection of antibodies to the tRNA(his) in a over a third of anti-Jo-1 sera; and the description of distinctive features of the histopathology of patients with anti-Jo-1. New information about the cellular role of the antigens was discovered, including a role for Mi-2 antigen in chromosomally-mediated regulation of transcription as part of a nucleosome remodeling complex, and a potential role for PM-Scl antigen in ribosomal RNA processing as part of an exosome. The reason for the production of the autoantibodies, and the reason particular antigens are targeted, are key questions. Recent studies have suggested that antigen cleavage during apoptosis, particularly by granzyme B, may be an important factor. Whether the antibodies play a role in tissue injury remains unknown.

​​——————————————————————–

7. Marie I, Hachulla E, Chérin P, Dominique S, Hatron PY, Hellot MF, Devulder B, Herson S, Levesque H, Courtois H. Interstitial lung disease in polymyositis and dermatomyositis. Arthritis Rheum. 2002 Dec 15;47(6):614-22. PMID:12522835.

Abstract

OBJECTIVES: To assess prevalence, characteristics, and long-term outcome of interstitial lung disease (ILD) in polymyositis (PM) and dermatomyositis (DM). To determine predictive variables of ILD course in PM/DM, and to define both clinical and biochemical features associated with ILD onset in PM/DM. METHODS: The medical records of 156 consecutive PM/DM patients in 3 medical centers were reviewed. RESULTS: Thirty-six PM/DM patients (23.1%) developed ILD. We observed that 19.4% of patients with ILD had resolution of pulmonary disorders, whereas 25% experienced ILD deterioration. Morbidity and mortality rates were as high as 13.9% and 36.4%, respectively, in PM/DM patients with ILD. Parameters of PM/DM that related to ILD poor outcome were identified as follows: Hamman-Rich-like pattern, initial diffusing capacity of carbon monoxide <45%, neutrophil alveolitis, and histologic usual interstitial pneumonia. Additionally, for the group with ILD, polyarthritis, higher values of erythrocyte sedimentation rate and C-reactive protein, presence of anti-Jo-1 antibody, and characteristic microangiopathy were significantly more frequent. CONCLUSION: Our series underlines the high frequency of ILD in PM/DM patients, resulting in increased morbidity and mortality rates. It also indicates that PM/DM patients should routinely be screened for ILD, even those patients without anti-Jo-1 antibody, because 69% of our ILD patients were seronegative for the anti-Jo-1 antibody. Our findings further suggest that PM/DM patients presenting with factors predictive of ILD poor outcome may require more aggressive therapy.

​​——————————————————————–

8. Miller T, Al-Lozi MT, Lopate G, Pestronk A. Myopathy with antibodies to the signal recognition particle: clinical and pathological features. J Neurol Neurosurg Psychiatry. 2002 Oct;73(4):420-8. PMID:12235311.

Abstract

OBJECTIVES: To study myopathies with serum antibodies to the signal recognition particle (SRP), an unusual, myositis specific antibody associated syndrome that has not been well characterised pathologically. METHODS: Clinical, laboratory, and myopathological features were evaluated in seven consecutive patients with a myopathy and serum anti-SRP antibodies, identified over three years. The anti-SRP myopathy was compared with myopathology in other types of inflammatory and immune myopathies. RESULTS: The patients with anti-SRP antibodies developed weakness at ages ranging from 32 to 70 years. Onset was seasonal (August to January). Weakness became severe and disability developed rapidly over a period of months. Muscle pain and fatigue were present in some patients. No patient had a dermatomyositis-like rash. Serum creatine kinase was very high (3000 to 25 000 IU/l). Muscle biopsies showed an active myopathy, including muscle fibre necrosis and regeneration. There was prominent endomysial fibrosis, but little or no inflammation. Endomysial capillaries were enlarged, reduced in number, and associated with deposits of the terminal components of complement (C5b-9, membrane attack complex). Strength improved in several patients after corticosteroid treatment. CONCLUSIONS: Myopathies associated with anti-SRP antibodies may produce severe and rapidly progressive weakness and disability. Muscle biopsies show active myopathy with pathological changes in endomysial capillaries but little inflammation. Corticosteroid treatment early in the course of the illness is often followed by improvement in strength. In patients with rapidly progressive myopathies and a high serum creatine kinase but little inflammation on muscle biopsy, measurement of anti-SRP antibodies and pathological examination of muscle, including evaluation of endomysial capillaries, may provide useful information on diagnosis and treatment.

​​——————————————————————–

9. Kao AH, Lacomis D, Lucas M, Fertig N, Oddis CV. Anti-signal recognition particle autoantibody in patients with and patients without idiopathic inflammatory myopathy. Arthritis Rheum. 2004 Jan;50(1):209-15. PMID:14730618.

​Abstract

OBJECTIVE: To determine the long-term outcome and associated clinical, serologic, and pathologic features in a cohort of patients with connective tissue disease (CTD) and the anti-signal recognition particle (anti-SRP) autoantibody. METHODS: Sera and clinical data were collected prospectively from consecutive adult patients with polymyositis (PM; n = 134), dermatomyositis (n = 129), or other CTDs (predominantly systemic sclerosis [SSc; n = 790]). Patients were first evaluated during 1973-2001. RESULTS: Nineteen patients with the anti-SRP autoantibody were identified, 16 (84%) of whom had pure PM and 3 (2 with SSc and 1 with antisynthetase syndrome) had yet to develop features of myositis after a mean followup of 4.5 years (range 2.5-6 years). More SRP-positive PM patients had severe proximal muscle weakness (50%) and muscle atrophy (67%) at initial presentation compared with antisynthetase-positive PM controls. Cardiac involvement occurred in only 2 of 16 SRP-positive PM patients (13%), and interstitial lung disease was noted in 3 of 13 SRP-positive PM patients (23%) and in the 3 SRP-positive nonmyositis patients. There was a relative lack of inflammation in muscle biopsy specimens from the SRP-positive PM cohort. Other autoantibodies in the SRP-positive patients included Ro/SSA (4 patients), Th/To (1 patient), and anti-PL-12 (1 patient). Survival in the SRP-positive PM patients was comparable with that seen in the cohort of SRP-negative PM patients. CONCLUSION: The anti-SRP autoantibody is not specific for PM. Severe muscle weakness and atrophy were prominent features in PM patients with anti-SRP. Cardiac involvement was less common and survival was better in patients with anti-SRP than has previously been reported.

​​——————————————————————–

10. Casciola-Rosen L, Nagaraju K, Plotz P, Wang K, Levine S, Gabrielson E, Corse A, Rosen A. Enhanced autoantigen expression in regenerating muscle cells in idiopathic inflammatory myopathy. J Exp Med. 2005 Feb 21;201(4):591-601. PMID:15728237.

Abstract

Unique autoantibody specificities are strongly associated with distinct clinical phenotypes, making autoantibodies useful for diagnosis and prognosis. To investigate the mechanisms underlying this striking association, we examined autoantigen expression in normal muscle and in muscle from patients with autoimmune myositis. Although myositis autoantigens are expressed at very low levels in control muscle, they are found at high levels in myositis muscle. Furthermore, increased autoantigen expression correlates with differentiation state, such that myositis autoantigen expression is increased in cells that have features of regenerating muscle cells. Consistent with this, we found that cultured myoblasts express high levels of autoantigens, which are strikingly down-regulated as cells differentiate into myotubes in vitro. These data strongly implicate regenerating muscle cells rather than mature myotubes as the source of ongoing antigen supply in autoimmune myositis. Myositis autoantigen expression is also markedly increased in several cancers known to be associated with autoimmune myositis, but not in their related normal tissues, demonstrating that tumor cells and undifferentiated myoblasts are antigenically similar. We propose that in cancer-associated myositis, an autoimmune response directed against cancer cross-reacts with regenerating muscle cells, enabling a feed-forward loop of tissue damage and antigen selection. Regulating pathways of antigen expression may provide unrecognized therapeutic opportunities in autoimmune diseases.

​​——————————————————————–

11. Miller FW, Waite KA, Biswas T, Plotz PH. The role of an autoantigen, histidyl-tRNA synthetase, in the induction and maintenance of autoimmunity. Proc Natl Acad Sci U S A. 1990 Dec;87(24):9933-7. PMID:1702223.

​Pdf-file not available

Abstract

Patients with systemic autoimmune diseases make specific autoantibodies that are directed against self structures. According to one view, these autoantibodies arise as a result of an immune response to foreign antigens such as infectious agents that share, by molecular mimicry, common structures with host proteins. An alternative view is that the target autoantigen itself initiates, selects, and sustains autoantibody synthesis. We show here that anti-Jo-1 autoantibodies directed against histidyl-tRNA synthetase in the human autoimmune muscle disease polymyositis undergo, in addition to spectrotype broadening and class switching, the sine qua non of an immune response to the target antigen–affinity maturation to that antigen. We demonstrate further that these autoantibodies, unlike anti-synthetase antibodies induced in mice immunized with heterologous antigen, bind only nonlinear epitopes on the native human synthetase that remain exposed when the enzyme is complexed to tRNA(His). These data suggest that the native target autoantigen itself has played a direct role in selecting and sustaining the autoantibody response and sharply restrict the time and the way in which a molecular mimic might act to provoke autoantibodies.

​​——————————————————————–

12. Eloranta ML, Barbasso Helmers S, Ulfgren AK, Rönnblom L, Alm GV, Lundberg IE.

A possible mechanism for endogenous activation of the type I interferon system in myositis patients with anti-Jo-1 or anti-Ro 52/anti-Ro 60 autoantibodies. Arthritis Rheum. 2007 Sep;56(9):3112-24. PMID:17763410.

 Abstract

OBJECTIVE: To investigate type I interferon (IFN) system activation and its correlation with autoantibodies and organ manifestations in polymyositis (PM), dermatomyositis (DM), and inclusion body myositis. METHODS: Sera from 30 patients and 16 healthy controls, or purified IgG, were combined with material released from necrotized cells to stimulate IFNalpha production by peripheral blood mononuclear cells (PBMCs) from healthy blood donors. Muscle biopsy specimens from 25 patients and 7 healthy controls were investigated for blood dendritic cell antigen 2 (BDCA-2)-positive plasmacytoid dendritic cells (PDCs) and IFNalpha/beta-inducible myxovirus resistance 1 (MX-1) protein. RESULTS: Sera from 13 patients who were positive for anti-Jo-1 or anti-Ro 52/anti-Ro 60 autoantibodies induced IFNalpha production in PBMCs when combined with necrotic cell material. In addition, IgG prepared from anti-Jo-1-positive PM sera induced IFNalpha with necrotic material, but not when the latter was treated with RNase. BDCA-2 expression in PDCs in muscle tissue was increased in PM patients with anti-Jo-1 autoantibodies, while MX-1 staining in capillaries was increased in DM patients, compared with healthy individuals. IFNalpha-inducing capacity correlated with interstitial lung disease, while MX-1 expression in the capillaries correlated with DM. CONCLUSION: Immune complexes containing anti-Jo-1 or anti-Ro 52/anti-Ro 60 autoantibodies and RNA may act as endogenous IFNalpha inducers that activate IFNalpha production in PDCs. These PDCs could be of importance for inducing myositis, whereas in DM patients without autoantibodies the presence of MX-1 protein in capillaries suggests another cellular IFNalpha source and induction mechanism. Consequently, the type I IFN system may be of importance in both PM and DM, but via different pathways.

​​——————————————————————–

13. Krystufková O, Vallerskog T, Helmers SB, Mann H, Putová I, Belácek J, Malmström V, Trollmo C, Vencovsky J, Lundberg IE. Increased serum levels of B cell activating factor (BAFF) in subsets of patients with idiopathic inflammatory myopathies. Ann Rheum Dis. 2009 Jun;68(6):836-43. Epub 2008 Jul 15. PMID:18628284.

​Abstract

OBJECTIVE: To investigate serum levels of B cell activating factor (BAFF) in patients with myositis and correlate these to autoantibody profile, clinical phenotype and treatment. METHODS: BAFF levels in sera from 49 patients with dermatomyositis, 44 with polymyositis, 6 with inclusion body myositis and 30 matched controls were measured by ELISA. Specific autoantibodies were detected by line blot and western blot assays. RESULTS: Serum levels of BAFF were significantly higher in patients compared to healthy controls (p = 0.003). Patients with anti-Jo-1 autoantibodies had higher BAFF levels than control individuals (p<0.003) or patients without any specific autoantibodies (p<0.05). Patients with dermatomyositis had higher BAFF levels compared to polymyositis (p<0.05). Patients with interstitial lung disease (ILD) had higher BAFF levels than patients without ILD (p<0.05) or controls (p<0.01) but this could be explained by presence of anti-Jo-1 autoantibodies. BAFF levels correlated with serum creatine kinase (CK) (rs = 0.365, p = 0.0005) but not with C-reactive protein (CRP) levels. A negative correlation of BAFF levels with glucocorticoid daily dose for all patients (rs = -0.292, p = 0.003) and with cumulative glucocorticoid doses in early myositis cases (rs = -0.659, p<0.001) was recorded. CONCLUSION: Our finding of elevated serum levels of BAFF in patients with myositis with described phenotypes together with the correlations between levels of BAFF and CK and a negative correlation with dose of glucocorticoids, indicate that BAFF could be a potential therapeutic target in such cases.

​​——————————————————————–

14. Hengstman GJ, van Venrooij WJ, Vencovsky J, Moutsopoulos HM, van Engelen BG. The relative prevalence of dermatomyositis and polymyositis in Europe exhibits a latitudinal gradient. Ann Rheum Dis. 2000 Feb;59(2):141-2. PMID:10666171.

Abstract not applicable

​——————————————————————–

15. Shamim EA, Rider LG, Pandey JP, O’Hanlon TP, Jara LJ, Samayoa EA, Burgos-Vargas R, Vazquez-Mellado J, Alcocer-Varela J, Salazar-Paramo M, Kutzbach AG, Malley JD, Targoff IN, Garcia-De la Torre I, Miller FW. Differences in idiopathic inflammatory myopathy phenotypes and genotypes between Mesoamerican Mestizos and North American Caucasians: ethnogeographic influences in the genetics and clinical expression of myositis. Arthritis Rheum. 2002 Jul;46(7):1885-93. PMID:12124873.

Abstract

OBJECTIVE: As part of a larger, worldwide study of the ethnogeography of myositis, we evaluated the clinical, serologic, and immunogenetic features of Mestizo (Mexican and Guatemalan) and North American Caucasian patients with idiopathic inflammatory myopathy (IIM). METHODS: Clinical manifestations, autoantibodies, HLA-DRB1 and DQA1 alleles, and immunoglobulin Gm/Km allotypes were compared between 138 Mestizos with IIM and 287 Caucasians with IIM, using the same classification criteria and standardized questionnaires. RESULTS: IIM in Mestizo patients was characterized by a higher proportion of dermatomyositis (69% of adult Mestizos versus 35% of adult Caucasians; P < 0.001) and anti-Mi-2 autoantibodies (30% versus 7% of adults, respectively, and 32% versus 4% of children, respectively; P < 0.01). Genetic risk factors also differed in these populations. Whereas Mestizos had no HLA risk factors for IIM, HLA-DRB1*0301, the linked allele DQA1*0501, and DRB1 alleles sharing the first hypervariable region motif (9)EYSTS(13) were major risk factors in Caucasian patients with IIM. Furthermore, different HLA-DRB1 and DQA1 alleles were associated with anti-Mi-2 autoantibodies (DRB1*04 and DQA1*03 in Mestizos and DRB1*07 and DQA1*02 in Caucasians). Immunoglobulin gamma-chain allotypes Gm(1), Gm(17) (odds ratio for both 11.3, P = 0.008), and Gm(21) (odds ratio 7.3, P = 0.005) and kappa-chain allotype Km(3) (odds ratio 7.3, P = 0.005) were risk factors for IIM in Mestizos; however, no Gm or Km allotypes were risk or protective factors in Caucasians. In addition, Gm and Km phenotypes were unique risk factors (Gm 1,3,17 5,13,21 and Gm 1,17 23 21 and Km 3,3) or protective factors (Km 1,1) for the development of myositis and anti-Mi-2 autoantibodies (Gm 1,2,3,17 23 5,13,21) in adult Mestizos. CONCLUSION: IIM in Mesoamerican Mestizos differs from IIM in North American Caucasians in the frequency of phenotypic features and in the immune-response genes predisposing to and protecting from myositis and anti-Mi-2 autoantibodies at 4 chromosomal loci. These and other data suggest the likelihood that the expression of IIM is modulated by different genes and environmental exposures around the world.

​​——————————————————————–

16. Chinoy H, Salway F, Fertig N, Shephard N, Tait BD, Thomson W, Isenberg DA, Oddis CV, Silman AJ, Ollier WE, Cooper RG; UK Adult Onset Myositis Immunogenetic Collaboration (AOMIC). In adult onset myositis, the presence of interstitial lung disease and myositis specific/associated antibodies are governed by HLA class II haplotype, rather than by myositis subtype. Arthritis Res Ther. 2006;8(1):R13. PMID:16507114.

Abstract

The aim of this study was to investigate HLA class II associations in polymyositis (PM) and dermatomyositis (DM), and to determine how these associations influence clinical and serological differences. DNA samples were obtained from 225 UK Caucasian idiopathic inflammatory myopathy patients (PM = 117, DM = 108) and compared with 537 randomly selected UK Caucasian controls. All cases had also been assessed for the presence of related malignancy and interstitial lung disease (ILD), and a number of myositis-specific/myositis-associated antibodies (MSAs/MAAs). Subjects were genotyped for HLA-DRB1, DQA1 and DQB1. HLA-DRB1*03, DQA1*05 and DQB1*02 were associated with an increased risk for both PM and DM. The HLA-DRB1*03-DQA1*05-DQB1*02 haplotype demonstrated strong association with ILD, irrespective of myositis subtype or presence of anti-aminoacyl-transfer RNA synthetase antibodies. The HLA-DRB1*07-DQA1*02-DQB1*02 haplotype was associated with risk for anti-Mi-2 antibodies, and discriminated PM from DM (odds ratio 0.3, 95% confidence interval 0.1-0.6), even in anti-Mi-2 negative patients. Other MSA/MAAs showed specific associations with other HLA class II haplotypes, irrespective of myositis subtype. There were no genotype, haplotype or serological associations with malignancy. The HLA-DRB1*03-DQA1*05-DQB1*02 haplotype associations appear to not only govern disease susceptibility in Caucasian PM/DM patients, but also phenotypic features common to PM/DM. Though strongly associated with anti-Mi-2 antibodies, the HLA-DRB1*07-DQA1*02-DQB1*02 haplotype shows differential associations with PM/DM disease susceptibility. In conclusion, these findings support the notion that myositis patients with differing myositis serology have different immunogenetic profiles, and that these profiles may define specific myositis subtypes.

​​——————————————————————–

17. Wedderburn LR, McHugh NJ, Chinoy H, Cooper RG, Salway F, Ollier WE, McCann LJ, Varsani H, Dunphy J, North J, Davidson JE; Juvenile Dermatomyositis Research Group (JDRG). HLA class II haplotype and autoantibody associations in children with juvenile dermatomyositis and juvenile dermatomyositis-scleroderma overlap. Rheumatology (Oxford). 2007 Dec;46(12):1786-91. Epub 2007 Nov 14. PMID:18003662.

Abstract

OBJECTIVES: To investigate a large cohort of children with juvenile dermatomyositis (JDM), and those with JDM-scleroderma (JDM-SSc) overlap, using detailed serological analysis, HLA class II genotyping and clinical characterization. METHODS: Children (114) with JDM were recruited, and clinical data collected, through the JDM National Registry and Repository (UK and Ireland). Sera were assayed for ANA using standard immunofluorescence techniques and specific antibodies characterized using ELISA, immunodiffusion and radioimmunoprecipitation. Patients and controls (n = 537) were genotyped at the HLA-DRB1 and DQB1 loci, and then the DQA1 locus data was derived. RESULTS: Over 70% of the patients were ANA-positive. Clear differences in serological and genetic data were demonstrated between JDM and JDM-SSc overlap groups. Strong associations were seen for HLA-DRB1*03 (all cases vs controls, P(corr) = 0.02; JDM-SSc vs controls, P(corr) = 0.001) and HLA-DQA1*05 (all cases vs controls, P(corr) = 0.01; JDM-SSc vs controls, P(corr) = 0.005). The frequency of the HLA-DRB1*03-DQA1*05-DQB1*02 haplotype was significantly increased in the JDM-SSc (P = 0.003) and anti-PM-Scl antibody (P = 0.002) positive groups. All anti-U1-RNP antibody-positive patients had at least one copy of HLA-DRB1*04-DQA1*03-DQB1*03 haplotype. Associations were observed between serology and specific clinical features. CONCLUSIONS: We present clinical data, HLA genotyping and serological profiling on a large cohort of JDM patients and a carefully characterized subset of patients with JDM-SSc overlap. The results confirm known HLA associations and extend the knowledge by stratification of data in serological and clinical subgroups. In the future, a combination of serological and genetic typing may allow for better prediction of clinical course and disease subtype in JDM.

​​——————————————————————–

18. Love LA, Leff RL, Fraser DD et al. A new approach to the classification of idiopathic inflammatory myopathy: myositis-specific autoantibodies define useful homogeneous patient groups. Medicine (Baltimore) 1991;70:360–74. PMID:1659647.

​Pdf-file not avalaible

​Abstract

The IIM are a heterogeneous group of systemic rheumatic diseases which share the common features of chronic muscle weakness and mononuclear cell infiltrates in muscle. A number of classification schemes have been proposed for them, but none takes into consideration the marked immunologic, clinical, and genetic heterogeneity of the various clinical groups. We compared the usefulness of myositis-specific autoantibodies (anti-aminoacyl-tRNA synthetases, anti-SRP, anti-Mi-2 and anti-MAS) to the standard clinical categories (polymyositis, dermatomyositis, overlap myositis, cancer-associated myositis, and inclusion body myositis) in predicting clinical signs and symptoms, HLA types, and prognosis in 212 adult IIM patients. Although patients with inclusion body myositis (n = 26) differed in having significantly more asymmetric and distal weakness, falling, and atrophy than other patients, there were few other significant differences among the other clinical groups. In contrast, autoantibody status defined distinct sets of patients and each patient had only 1 myositis-specific autoantibody. Patients with anti-amino-acyl-tRNA synthetase autoantibodies (n = 47), compared to those without these antibodies, had significantly more frequent arthritis, fever, interstitial lung disease, and “mechanic’s hands”; HLA-DRw52; higher mean prednisone dose at survey, higher proportion of patients receiving cytotoxic drugs, and higher death rates. Those with anti-signal recognition particle antibodies (n = 7) had increased palpitations; myalgias; DR5, DRw52; severe, refractory disease; and higher death rates. Patients with anti-Mi-2 antibodies (n = 10) had increased “V-sign” and “shawl-sign” rashes, and cuticular overgrowth; DR7 and DRw53; and a good response to therapy. The 2 patients with anti-MAS antibodies were the only ones with alcoholic rhabdomyolysis preceding myositis; both had insulin-dependent diabetes mellitus, and both had HLA-B60, -C3, -DR4, and -DRw53. These findings suggest that myositis-specific autoantibody status is a more useful guide than clinical group in assessing patients with myositis, and that specific associations of immunogenetics, immune responses, and clinical manifestations occur in IIM. Thus the myositis-specific autoantibodies aid in interpreting the diverse symptoms and signs of myositis patients and in predicting their clinical course and prognosis. We propose, therefore, that an adjunct classification of the IIM, based on the myositis-specific autoantibody status, be incorporated into future studies of their epidemiology, etiology, and therapy.

​​——————————————————————–

19. Lundberg IE, Barbasso Helmers S. The type I interferon system in idiopathic inflammatory myopathies. Autoimmunity. 2010 Apr;43(3):239-43. PMID:20187702.

Abstract

Polymyositis (PM), dermatomyositis (DM) and inclusion body myositis (IBM) are chronic inflammatory diseases that are characterized by muscle weakness and inflammatory cells in muscle tissue. Autoantibodies are common, some of them are specific for myositis, the most frequent being the anti-Jo-1 antibody which is associated not only with myositis but also with interstitial lung disease and arthritis. A role of type I interferons in disease mechanisms of myositis was first supported by the reported onset of PM and DM during treatment with type I interferon. More recently an interferon signature has been reported in muscle tissue of DM and PM patients both as gene and protein expression, and type I IFN expression in peripheral blood cells seems to correlate with disease activity. Different mechanisms could induce type I interferon in PM and DM like viral infections or endogenous factors as suggested by the observation that sera from myositis patients with anti-Jo-1 antibodies as well as anti-SSA and anti-SSB antibodies have an interferon inducible capacity. Accumulating data indicate a role of the type I interferon in myositis, particularly in juvenile and adult DM and in anti-Jo-1 or anti-SSA positive PM.

​​——————————————————————–

20. Alexanderson H, Lundberg IE. Exercise as a therapeutic modality in patients with idiopathic inflammatory myopathies. Curr Poin Rheumatol. 2012 Mar;24(2):201-7. PMID:22189517.

Abstract

Purpose of review: To present scientific evidence on clinical and molecular effects of exercise in adult and juvenile idiopathic inflammatory myopathies focusing on recent studies.

Recent findings: In patients with inclusion body myositis (IBM), one small, open study recently for the first time reported on improved muscle strength and functional capacity after a twice-a-day home exercise programme, whereas earlier studies have not been able to show any or only small improvements, mainly in less-affected muscle groups. For patients with polymyositis and dermatomyositis a few studies have reported reduced clinical disease activity after resistance training in patients with chronic phase of disease. These observations are supported by downregulation of genes regulating inflammation and fibrosis in muscle tissue following this type of training. These results may indicate that resistance exercise might reduce muscle inflammation in adult polymyositis and dermatomyositis. A first case report has described safety and benefits of an exercise programme in a child with dermatomyositis, and a few studies support the safety of single exercise bouts or exercise tolerance tests in juvenile dermatomyositis.

Summary: Accumulated evidence supports safety and efficacy of exercise in polymyositis and dermatomyositis, although data are more inconclusive for efficacy in patients with IBM. There is a need for larger studies to further ensure efficacy in IBM and juvenile dermatomyositis.

Comments are closed.