The characteristic intracellular localization of HBD-3 near markers of degeneration and autophagy, and overexpression of endosomal TLR3 in sIBM hint at different pathogenetic mechanisms in sIBM compared with PM.
TLR3 was upregulated particularly in JDM, being localized on vascular endothelial cells, muscle infiltrating cells (mainly myeloid dendritic cells), and regenerating myofibers; TLR7 and TLR9 proteins were present in IIM (prominently in PM), mainly on cell infiltrates, particularly plasma cells, and on some injured myofibers.
To assess the expression of Toll-like receptor 3 (TLR-3) and TLR-7 in muscle tissue from patients with polymyositis (PM) and dermatomyositis (DM) and to investigate the function and regulation of TLR-3 in cultured muscle cells.