Abstract-Text (inkl. Referenzen)

Introduction: Conventional cell culture models for the investigation of chronic muscle inflammation do not display functional aspects. Aim of the study is to identify relevant cell stress pathways in inclusion body myositis (e.g. ER Stress or proteasome inhibition) contributing to muscle weakness using 3D engineered skeletal muscle (ESM) for functional analysis.

Material and methods: Human primary muscle cells were used for the generation of ESM and for conventional 2D monolayer cell cultures. For ESM also fibroblasts were added. ESM and monolayer cell cultures were exposed to IFN-γ+IL-1β, Rapamycine, Chloroquin, DetaNONOate, MG132, Epoxomicin and Tunicamycin to simulate cell stress during muscle inflammation. Isometric force measurements were applied to analyze ESM function. Further, the gene expression (MHC-I, IL1B, CXCL-9, MyoD, Pax7, XBP1, HSP90B1) of ESM was compared with 2D cultures.

Results: Exposure to IFN-γ+IL-1β, the proteasome inhibitors MG132 and Epoxomicin led to reduced contraction force of ESM by 21.6%, 74% and 94% at 60Hz stimulation frequency (p<0.05, p<0.05 and p<0.001 over all tested frequencies). Expression analysis revealed similar inflammatory patterns between IFN-γ+IL-1β exposed ESM and 2D myocytes.

Discussion: Of the various stress conditions tested, proinflammatory cytokines and proteasome inhibitors induced muscle weakening in ESM. ESM may be a useful model to test disease mechanisms and screen for treatment options in inflammatory muscle disease.