Limosilactobacillus fermentum MG5091 and Lactococcus lactis MG4668 and MG5474 Suppress Muscle Atrophy by Regulating Apoptosis in C2C12 Cells

Muscular atrophy is a chronic muscle disease characterized by a loss of muscle mass and muscle weakness due to excessive protein breakdown relative to protein synthesis. Apoptosis is a major factor in sarcopenia and the final stage of muscle atrophy that occurs via various mechanisms. In this study, we evaluated the protective effects of cell-free supernatants (CFSs) from different lactic acid bacteria (LAB) strains in dexamethasone (DEX)-treated C2C12 cells, followed by probiotic properties. We found that Limosilactobacillus fermentum (L. fermentum) MG4263 and MG5091 and Lactococcus lactis (Lc. lactis) MG4668 and MG5474 inhibited muscle atrophy F-box (atrogin-1) and muscle-specific RING-finger protein-1 (MuRF-1) in DEX-treated C2C12 cells. In addition, LAB strains inhibited the expression of apoptotic proteins, such as Bcl-2-associated X (Bax)/Bcl-2 and caspase-3 in DEX-treated C2C12 cells. L. fermentum MG5091, Lc. lactis MG4668, and MG5474 showed high survival rates in gastrointestinal (GIT) conditions and high adhesion rate to HT-29 cells. The LAB strains were also assessed for hemolysis and toxicity in HT-29 cells to confirm their stability. The LAB strains showed no hemolytic activity and toxicity to HT-29 cells. Therefore, L. fermentum MG5091, Lc. lactis MG4668, and MG5474 suggest their potential as probiotics to be used as functional foods for the inhibition of muscular atrophy.