ABSTRACT: Idiopathic inflammatory myopathies (polymyositis and dermatomyositis) are heterogeneous group of muscle disorders of unknown etiology.The pathogenic pathways responsible for muscle fiber damage and dysfunction in myositis are not currently well defined. Identification of such pathways may help to design novel therapeutic interventions and also help to develop diagnostic tests. Keywords: Development or differentiation design
Project description:Idiopathic inflammatory myopathies (polymyositis and dermatomyositis) are heterogeneous group of muscle disorders of unknown etiology.The pathogenic pathways responsible for muscle fiber damage and dysfunction in myositis are not currently well defined. Identification of such pathways may help to design novel therapeutic interventions and also help to develop diagnostic tests. Experiment Overall Design: Muscle biopsies from a separate group of 5 adult untreated female DM patients were profiled and compared to muscle tissue of normal human healthy volunteers to define molecular pathways in muscle of myositis patients. Confirm and map key pathway members to specific cell types in the muscle tissue of patients and controls using RT-PCR, Western blotting and Immunolocalization.
Project description:Expression profiling of human myositis muscle samples This study was designed to compare expression signatures among the various types of inflammatory myopathy, dermatomyositis (DM), inclusion body myositis (IBM), necrotizing myopathy (NM), nonspecific myopathy (NS), and polymyositis (PM) compared to normal (NL) muscle.
Project description:Microarray data from muscle biopsy specimens from subjects with inclusion body myositis, polymyositis, and normals Experiment Overall Design: Microarray experiments
Project description:Microarray data from muscle biopsy specimens from subjects with inclusion body myositis, polymyositis, and normals Keywords: Research study
Project description:Idiopathic inflammatory myopathies (IIMs) are severe autoimmune diseases whose pathogenetic mechanisms are still poorly understood. Invalidation of the inducible T cell co-stimulator (Icos) gene on the diabetes-prone NOD mouse background leads to spontaneous autoimmune myositis, providing a tool for studying the pathophysiological mechanisms involved in muscle inflammation. Myositis in Icos-/- NOD mice is characterized by progressive muscle weakness with immune cell infiltration and expression of IFN-associated genes, thus resembling human myositis. Proteomic and spatial transcriptomic analysis of Icos-/- NOD mice muscle brought to light a profound metabolic dysregulation in myofibers. Electron microscopy analysis, mitochondrial respiration assessment and histoenzymology stainings revealed dramatic structural abnormalities and severe dysfunction of muscle mitochondria in diseased Icos-/- NOD mice. Consequently, muscle from these mice exhibited elevated reactive oxygen species (ROS) production and an oxidative stress-transcriptomic signature. Blocking IFN in Icos-/- NOD mice diminished immune cell infiltration and ROS production. Transcriptomic analysis of muscle biopsies from IIMs patients revealed a negative correlation between IFN and mitochondrial gene expression levels, and treatment of human myoblasts with IFN reduced the expression of mitochondrial respiratory chain genes, suggesting a link between IFN production and mitochondrial dysfunction. Sustaining a relevant pathogenic role for oxidative stress in the disease, preventive and therapeutic ROS-buffer treatments also significantly alleviated myositis while preserving mitochondrial ultrastructure and restoring muscle mitochondrial respiration in mice. Notably, preventive ROS-buffer treatment also reduced muscle inflammation. Together, our results suggest that ROS, mitochondrial dysfunction and inflammation are interconnected in a self-maintenance loop, opening perspectives for ROS targeting drugs and/or mitochondria therapy in myositis.
Project description:To identify changes in skeletal muscle microRNA expression after exercise and associate the identified microRNAs with mRNA and protein expression to disease-specific pathways in polymyositis and dermatomyositis
Project description:To identify changes in skeletal muscle microRNA expression after exercise and associate the identified microRNAs with mRNA and protein expression to disease-specific pathways in polymyositis and dermatomyositis
Project description:MHC-I overexpression in muscle biopsies is a hallmark of inflammatory myopathies.However the mechanisms of MHC-I overexpression in each disease is not well understood. Microarray analysis from MHC-I-microdissected myofibers showed a differential expression signature in each inflammatory myopathy. Innate immunity and IFN-I pathways are upregulated vs healthy controls, specifically in dermatomyositis (DM). RNA from MHC-I-positive myofibers were obtained from muscle biopsies of 5 patients with dermatomyositis, 5 with polymyositis, 4 with inclusion body myositis and normal looking fibers from healthy controls.
Project description:Objective: In idiopathic inflammatory myopathies (IIM) infiltration of immune cells into muscle and upregulation of MHC-I expression implies increased antigen presentation and involvement of the proteasome system. To decipher the role of immunoproteasomes in myositis, we investigated individual cell types and muscle tissues and focused on possible immune triggers. Methods: Expression of constitutive (PSMB5, -6, -7) and corresponding immunoproteasomal subunits (PSMB8, -9, -10) was analyzed by real-time RT-PCR in muscle biopsies and sorted peripheral blood cells of patients with IIM, non-inflammatory myopathies (NIM) and healthy donors (HD). Protein analysis in muscle biopsies was performed by western blot. Affymetrix HG-U133 platform derived transcriptome data from biopsies of different muscle diseases and from immune cell types as well as monocyte stimulation experiments were used for validation, coregulation and coexpression analyses. Results: Real-time RT-PCR revealed significantly increased expression of immunoproteasomal subunits (PSMB8/-9/-10) in DC, monocytes and CD8+ T-cells in IIM. In muscle biopsies, the immunosubunits were elevated in IIM compared to NIM and exceeded levels of matched blood samples. Proteins of PSMB8 and -9 were found only in IIM but not NIM muscle biopsies. Reanalysis of 78 myositis and 20 healthy muscle transcriptomes confirmed these results and revealed involvement of the antigen processing and presentation pathway. Comparison with reference profiles of sorted immune cells and healthy muscle confirmed upregulation of PSMB8 and -9 in myositis biopsies beyond infiltration related changes. This upregulation correlated highest with STAT1, IRF1 and IFNM-NM-3 expression. Elevation of T-cell specific transcripts in active IIM muscles was accompanied by increased expression of DC and monocyte marker genes and thus reflects the cell type specific involvement observed in peripheral blood. Conclusions: Immunoproteasomes seem to indicate IIM activity and suggest that dominant involvement of antigen processing and presentation may qualify these diseases exemplarily for the evolving therapeutic concepts of immunoproteasome specific inhibition. Investigation of constitutive and immunoproteasomal subunit expression in muscle tissue of patients with inflammatory and non-inflammatory myopathies These transcriptomes were used as reference signatures of different immune cell types in order to estimate the contribution of immune cell transcripts to the muscle transcriptomes investigated in the datasets GSE2044, GSE3112, GSE5370, GSE39454, GSE3307, GSE13205, GSE10685.