Il progetto di ricerca svolto durante il dottorato ha previsto lo studio di alcune forme di miopatia infiammatoria idiopatiche. Queste costituiscono un gruppo eterogeneo di malattie muscolari distinguibili tra loro clinicamente, istologicamente e patogeneticamente, ma che condividono la presenza di infiltrati infiammatori a livello muscolare. Sono classificate in tre gruppi: polimiosite, dermatomiosite e miosite a corpi inclusi. L’eziologia autoimmune per le forme di dermatomiosite e polimiosite e’ comprovata da alcune osservazioni (la presenza di autoanticorpi circolanti, l’associazione con altre patologie autoimmuni e la responsivita’ alle terapie con steroidi). E’ nota anche l’associazione di polimiosite e dermatomiosite con alcune forme neoplastiche. Solitamente la diagnosi di neoplasia precede o segue di 3/5anni la comparsa della miopatia. L’ipotesi patogenetica per le forme paraneoplastiche e’ che gli antigeni del tumore causano la produzione di autoanticorpi che cross-reagiscono con componenti del muscolo scheletrico. Ad oggi non sono ancora noti gli antigeni muscolo-specifici responsabili della miopatia, ne’ nelle forme idiopatiche, ne’nelle forme paraneoplastiche. Lo scopo di questo studio e’ stato quello di individuare gli auto-antigeni muscolo-specifici riconosciuti dagli anticorpi circolanti dei pazienti. Sono stati analizzati 150 sieri provenienti da controlli e pazienti. L’impiego delle moderne tecniche di 2D-PAGE e di immunomica associate alla massa, ha permesso di individuare una serie di antigeni miosite-specifici e miosite-associate, nonche’ alcuni markers paraneoplstici specifici per le forme associate ai tumori della mammella, del polmone e dell’ovaio. Le stesse tecniche sono state impiegate anche per lo studio di altre patologie muscolari. In particolare sono state individuate alcune proteine muscolari riconosciute in maniera specifica dal siero di alcuni pazienti affetti da miopatia necrotizzante. Abbiamo notato l’attivazione del sistema del complemento e la deposizione di IgG sulla membrana plasmatica di fibre muscolari non necrotiche. Dall’analisi proteomica abbiamo individuato auto-anticorpi circolanti presenti in maniera specifica nei sieri dei pazienti affetti da miopatia necrotizzante e non nei casi controllo. Abbiamo poi applicato questa metodica di proteomica per lo studio di alcune forme di miopatia miofibrillare. Questa patologia e’ caratterizzata dalla presenza di accumuli di proteine (desmina, miotilina, alfa-B cristallina e altre) all’interno delle fibre muscolari. L’analisi genetica delle proteine presenti negli accumuli ha evidenziato la presenza di mutazioni. La presenza di mutazioni, pero’, e’ stata individuata in una piccola percentuale di pazienti. L’eziologia di questa patologia e’ sconosciuta. Nello studio, abbiamo individuato la compresenza di una risposta infiammatoria a livello muscolare e la presenza di accumuli intracellulari tipiche delle miopatie miofibrillari in due pazienti. In questi pazienti sono state escluse mutazioni nei geni solitamente coinvolti in questa patologie. Dallo studio di proteomica e immunomica, abbiamo individuato alcune proteine riconosciute in maniera specifica dai sieri di questi pazienti e non dai casi controllo. Abbiamo quindi individuato per la prima volta un sottogruppo di miopatie mio fibrillari immuno-mediate.
The research project carried out during the PhD was about the idiopathic inflammatory myopathies. They are classified into three groups: polymyositis, dermatomyositis and inclusion body myositis These acquired diseases have in common the presence of moderate to severe muscle weakness and endomysial inflammation, but each subset retains characteristic clinical, immunopathological, and morphological features. The autoimmune etiology for dermatomyositis and polymyositis is supported by some observations (the presence of circulating autoantibodies, the association with other autoimmune diseases and responsiveness to steroid treatment). The association between malignancy and autoimmune myositis has been largely described and confirmed by numerous epidemiological studies The diagnosis of the malignancy may occur before, concurrently to, or following the diagnosis of myositis but despite this potentially confusing observation, what is quite useful is the knowledge that cancer is usually recognized within 3-5 years of myositis diagnosis, with most diagnoses within 12 months. Is not completely understood if antigens are shared between muscle and tumor cells or if there is a cross-reactivity between some epitopes expressed in both cell types Despite the presence of a humorally-mediated inflammatory response targeting muscle fibers in DM, PM and OS, specific muscle antigens are not yet identified. In the study we characterized the muscle-specific proteins recognized by sera of patients with DM and PM and OS using a 2-DE approach. We also evaluated the sera of patients with myositis and cancer to validate the hypothesis of causal link between the diseases The same techniques were used for the study of other muscle diseases. We identified some muscle proteins specifically recognized by serum of some patients with immune mediated necrotizing myopathy. We found the activation of the complement system and deposition of IgG on the plasma membrane of non necrotic fibers. With proteomic analysis we identified circulating autoantibodies specifically present in the sera of patients with necrotizing myopathy and not in control cases. We then applied this method in proteomics for the study of certain forms of myofibrillar myopathy. This pathologies is characterized by accumulation of proteins (desmin, myotilin, alpha-B crystalline and others) within the muscle fibers. Genetic analysis of proteins present in the deposits showed the presence of mutations. The presence of mutations, however, 'and' have been identified in a small percentage of patients. The etiology of this disease is still unknown. In the study, we identified the presence of inflammatory responses in the muscle and the presence of intracellular accumulation typical of myofibrillar myopathy in two patients. In these patients were excluded mutations in the genes usually involved in this disease. With proteomic study we have identified proteins specifically recognized by sera from these patients and not by control cases. We then identified for the first time a subset of immune-mediated myofibrillar myopathy.
Specific serological profiles in patients with inflammatory myopathies
MARINI, Matteo
2010-01-01
Abstract
The research project carried out during the PhD was about the idiopathic inflammatory myopathies. They are classified into three groups: polymyositis, dermatomyositis and inclusion body myositis These acquired diseases have in common the presence of moderate to severe muscle weakness and endomysial inflammation, but each subset retains characteristic clinical, immunopathological, and morphological features. The autoimmune etiology for dermatomyositis and polymyositis is supported by some observations (the presence of circulating autoantibodies, the association with other autoimmune diseases and responsiveness to steroid treatment). The association between malignancy and autoimmune myositis has been largely described and confirmed by numerous epidemiological studies The diagnosis of the malignancy may occur before, concurrently to, or following the diagnosis of myositis but despite this potentially confusing observation, what is quite useful is the knowledge that cancer is usually recognized within 3-5 years of myositis diagnosis, with most diagnoses within 12 months. Is not completely understood if antigens are shared between muscle and tumor cells or if there is a cross-reactivity between some epitopes expressed in both cell types Despite the presence of a humorally-mediated inflammatory response targeting muscle fibers in DM, PM and OS, specific muscle antigens are not yet identified. In the study we characterized the muscle-specific proteins recognized by sera of patients with DM and PM and OS using a 2-DE approach. We also evaluated the sera of patients with myositis and cancer to validate the hypothesis of causal link between the diseases The same techniques were used for the study of other muscle diseases. We identified some muscle proteins specifically recognized by serum of some patients with immune mediated necrotizing myopathy. We found the activation of the complement system and deposition of IgG on the plasma membrane of non necrotic fibers. With proteomic analysis we identified circulating autoantibodies specifically present in the sera of patients with necrotizing myopathy and not in control cases. We then applied this method in proteomics for the study of certain forms of myofibrillar myopathy. This pathologies is characterized by accumulation of proteins (desmin, myotilin, alpha-B crystalline and others) within the muscle fibers. Genetic analysis of proteins present in the deposits showed the presence of mutations. The presence of mutations, however, 'and' have been identified in a small percentage of patients. The etiology of this disease is still unknown. In the study, we identified the presence of inflammatory responses in the muscle and the presence of intracellular accumulation typical of myofibrillar myopathy in two patients. In these patients were excluded mutations in the genes usually involved in this disease. With proteomic study we have identified proteins specifically recognized by sera from these patients and not by control cases. We then identified for the first time a subset of immune-mediated myofibrillar myopathy.
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