Immunohistochemical and ultrastructural analysis of sporadic inclusion body myositis: a case series.

Sporadic inclusion body myositis (s-IBM) is a progressive, skeletal muscle disease with poor prognosis. However, establishing the final diagnosis is difficult because of the lack of clear biomarkers in the blood serum and very slow development of clinical symptoms. Moreover, most other organs function normally without any disturbance. Here, in patients with this untreatable disease, we have underlined the importance of immunohistochemical and ultrastructural assessment of skeletal muscle in patients diagnosed with s-IBM. The goal of this study was to identify the distribution of specific antigens and to determine morphological features in order to localize pathological protein aggregates, rimmed vacuoles, and loss of myofibrils, which are key elements in the diagnosis of s-IBM. All studied patients were between 48 and 83 years of age and were hospitalized in the Department of Rheumatology and Internal Medicine between 2011 and 2016. Anamneses revealed an accelerated progression of muscle atrophy, weakness of limb muscles, and difficulties with climbing stairs. Based on histopathology and transmission electron microscopy examination, inflammatory infiltrations consisting of mononuclear cells, severe atrophy and focal necrosis of myofibers, splitting of myofilaments, myelinoid bodies and rimmed vacuoles were observed. Primary antibodies directed against CD3, CD8, CD68, cN1A, beta-amyloid, Tau protein and apolipoprotein B made it possible to identify types of cells within infiltrations as well as the protein deposits within myofibers. Using a combination of immunohistochemistry and electron microscopy methods, we were able to establish the correct final diagnosis and to implement a specific treatment to inhibit disease progression.

The role of p62/SQSTM1 in sporadic inclusion body myositis.

We examined selective autophagy against ubiquitinated protein aggregates in sporadic inclusion body myositis (s-IBM) patients. The form of autophagy requires phosphorylation of serine 403 in p62/SQSTM1 to bind to Lys63-linked ubiquitin and the binding of the p62-ubiquitinated protein conjugates to LC3. In muscle biopsy specimens from 16 s-IBM patients, we compared the distribution of p62 (aa120-440) with 1) Ser403-phosphorylated p62 (S403-pp62), 2) Lys63-linked ubiquitin and 3) LC3 in double-colour immunofluorescence microscopy. S403-pp62, Lys63-linked ubiquitin and LC3 colocalised with p62 aggregates, 79.05% ± 13.64% (mean ± SD), 66.54% ± 19.91% and 51.84% ± 14.1%, respectively. Although positive deposits of S403-pp62 and Lys63-linked ubiquitin were always observed within p62 aggregates, LC3 often showed dissociated distribution from p62. We also found fibres containing small, numerous p62-positive dots that were negative for all three markers and were also observed in myositis controls. The results indicate that p62, Lys63-linked ubiquitin and LC3 in s-IBM join to perform selective autophagy. p62 could be induced by some cellular stresses in all types of myositis; however, in s-IBM, compromised binding of the p62-ubiquitinated protein complex to LC3 could stop the autophagy process in its initial stages, which causes the formation of aggregates of p62-oligomers with Lys63-ubiquitinated proteins.

Long non-coding RNAs: a new frontier in the study of human diseases.

With the development of whole genome and transcriptome sequencing technologies, long noncoding RNAs (lncRNAs) have received increased attention. Multiple studies indicate that lncRNAs act not only as the intermediary between DNA and protein but also as important protagonists of cellular functions. LncRNAs can regulate gene expression in many ways, including chromosome remodeling, transcription and post-transcriptional processing. Moreover, the dysregulation of lncRNAs has increasingly been linked to many human diseases, especially in cancers. Here, we reviewed the rapidly advancing field of lncRNAs and described the relationship between the dysregulation of lncRNAs and human diseases, highlighting the specific roles of lncRNAs in human diseases.