sIBM RNA-seq
Sporadic inclusion body myositis (sIBM) is a clinicopathologically defined muscle disease of older people. The pattern of the affected muscles including finger flexor and knee extensor and dysphagia are characteristic of sIBM. Muscle biopsy of sIBM shows rimmed vacuoles and inflammatory cell invasion into non-necrotic muscle fibers. The pathomechanism of sIBM is not fully elucidated yet. Controversy exists as to whether sIBM is a primary autoimmune disease or a degenerative muscle disease with secondary inflammation. The involvement of interferon-gamma mediated signaling pathway, myeloid dendritic and plasma cells, and highly differentiated cytotoxic T cells8 in sIBM pathology has been reported. Anti-cytosolic 5'-nucleotidase 1A autoantibodies are found in the serum of patients with sIBM. However, sIBM is usually refractory to immunosuppressive therapy. Muscle degeneration is an important aspect of sIBM etiology. Muscle biopsy is necessary for the diagnosis of sIBM. The rest of the diagnostic samples can be used for research, such as in gene expression profiling; for example, gene sets to differentiate sIBM biopsy samples from other myositis using support vector machine-learning system are revealed. Other groups analyzed two microarray datasets, derived from the Gene Expression Omnibus database and picked-up genes as a hub of a pathological network. As the pathology of sIBM shows the involvement of cells such as inflammatory cell infiltration, fibrosis, and adipose tissues, the expression data analysis might be confounded by non-muscle cells. Previously, we established a method of collecting CD56-positive myoblasts from human skeletal muscles derived from muscle biopsy samples. We hypothesized that the myoblasts derived from these patients are useful to see the cell-autonomous pathomechanism of sIBM. With these resources, we differentiated myoblasts into myotubes and analyze the expression profiles of the cell-autonomous pathology of sIBM.