Methyl 3,4-Dihydroxybenzoate

Inflammatory cell infiltration and myofiber necrosis are pathological hallmarks of idiopathic inflammatory myopathies (IIM). Methyl 3,4-dihydroxybenzoate (MDHB) is a natural phenolic acid compound, renowned for its anti-inflammatory and antioxidant effects. In this study, we investigated its protective mechanisms targeting muscle fiber necrosis and macrophage pyroptosis by regulating oxidative stress in IIM. In the present study, we found that increased reactive oxygen species (ROS) level and decreased nuclear factor erythroid 2 related factor 2 (Nrf2) protein expression were shown on the muscle fibers of experimental autoimmune myositis (EAM). Receptor-interacting protein 1 (RIPK1) and receptor-interacting protein 3 (RIPK3) protein expression were elevated in EAM. In vitro, MDHB protected C2C12 cells and myotubes against H₂O₂-induced cell viability damage. MDHB decreased the levels of oxidative stress such as ROS, and mitochondrial superoxide (MitoSOX), and rescued mitochondrial membrane potential and ATP generation. MDHB inhibited necroptosis of the C2C12 cells and myotubes under H₂O₂ stimulation in a dose-dependent manner. Furthermore, MDHB suppressed lipopolysaccharide and nigericin-induced caspase-1 cleavage and interleukin (IL-1β) secretion, indicating suppression of macrophage pyroptosis in vitro. In vivo, treatment with MDHB suppressed EAM-induced muscle weakness and inflammation. MDHB decreased ROS accumulation, and increased Nrf2 and heme oxygenase-1 (HO-1) expression in EAM mice's muscles, thereby inhibiting necroptosis of inflamed muscle species and macrophage pyroptosis. In conclusion, we demonstrated that MDHB could be a novel therapy for IIM that alleviates inflammation, muscle fiber necroptosis, and macrophage pyroptosis by regulating the Nrf2/HO-1 pathway.