7-Ketolithocholic Acid Attenuates Oxidative Injury and Senescence-Associated Phenotypes in Feline Skeletal Muscle Stromal Cells Through SREBP-Associated Lipid Metabolic Regulation

Skeletal muscle-derived stromal cells represent a resident stromal population of skeletal muscle and contribute to tissue homeostasis and regeneration. However, the metabolic mechanisms linking oxidative stress and cellular senescence in skeletal muscle stromal cells remain poorly understood. Here, we evaluated the effects of palmitoylethanolamide, conjugated linoleic acid, 7-ketolithocholic acid (7KA), and phenylacetylglycine in an H2O2-induced oxidative injury model (2 mM, 2 h) established using feline skeletal muscle stromal cells (FSMSCs). Among the four compounds, 7KA exhibited the strongest protective activity, significantly improving cell viability from 76.48% in H2O2-treated cells to 90.71 ± 4.89% following 80 μM 7KA treatment, while reducing lactate dehydrogenase release from 146.00 ± 2.60% to 71.62 ± 6.78% (both p < 0.05). Furthermore, 7KA alleviated oxidative damage, inflammatory responses, and senescence-associated phenotypes, reducing MDA levels from 380.05 ± 21.10 to 147.49 ± 34.48 nmol/mg, decreasing TNF-α, MCP-1, IL-6, and IL-8 levels, and increasing NAD+ and ATP levels from 3.12 ± 0.18 to 5.15 ± 0.09 μmol/g and from 11.91 ± 0.12 to 15.12 ± 1.37 μmol/g, respectively (p < 0.05). 7KA also improved mitochondrial membrane potential and reduced senescence-associated β-galactosidase activity. Transcriptomic analysis revealed that 7KA markedly modulated fatty acid metabolism and unsaturated fatty acid biosynthesis and attenuated TNF-associated inflammatory signaling. These changes were accompanied by restoration of SREBP1, SCD1, and FADS2 protein abundance. Pharmacological inhibition of SREBP with Fatostatin markedly attenuated the protective effects of 7KA, indicating that SREBP-associated lipid metabolic regulation contributes to these effects. Untargeted metabolomics further revealed alterations in lipid- and redox-related metabolites following 7KA treatment. Collectively, our findings indicate that 7KA attenuates oxidative injury and senescence-associated phenotypes in FSMSCs, with SREBP-associated lipid metabolic regulation playing an important role in its protective effects.