Sporadic Inclusion Body Myositis Underling Mitochondrial Dysfunction Ameliorated by Mitochondrial Homing Drug, MA-5

Background: Sporadic inclusion body myositis (sIBM) is the most common idiopathic inflammatory myopathy, and mitochondrial abnormalities may be involved. Methods: We recruited 9 sIBM patients and we examined mitochondrial functions with bioenergetic and examinations and dynamics of patient myoblasts with measuring a mitochondrial disease marker growth differential factor 15 (GDF15). We also examined the effect of a new candidate drug, Mitochondria acid-5 (MA-5). Findings: Bioenergetic analysis of sIBM patient myoblasts revealed damaged mitochondrial function with decreased ATP, mitochondrial size and impaired mitochondrial dynamics and cell vulnerability. MA-5 increased the ATP level and reduced mitochondrial ROS, following the protection against cell death. The reduced levels of Opa1 and Drp1 showed the impairment of mitochondrial fusion/fission process and that MA-5 ameliorated. Skin fibroblasts from sIBM patients can be used for diagnosis. Interpretation: GDF15 and MA-5 could provide both a new maker and therapeutic strategy for sIBM patients. Funding Statement: These works were supported in part by National grant-in-aid for scientific research from the Ministry of Education, Culture, Sports, Science, and Technology of Japan (18H02822), Translational Research Network Program (C50) from Japan Agency for Medical Research and Development (AMED). MEXT and AMED, JAPAN. Declaration of Interests: The authors state: "None." Ethics Approval Statement: Myoblasts and fibroblasts obtained by muscle and skin biopsy of sIBM patients were collected in Tohoku University Hospital under the approval of the Ethical Committee of Tohoku University.