Elevated Circulating Ceramides 18:0 and 24:1 as a Risk Factor for Sarcopenia: In Vitro, Animal, and Clinical Evidence.

BACKGROUND: Ceramides have garnered considerable attention as pro-aging bioactive lipids implicated in both metabolic dysfunction and musculoskeletal decline. Among these, C18:0 and C24:1 ceramides may play a role in the pathophysiology of sarcopenia, a key manifestation of age-related deterioration. However, their specific contributions to muscle degeneration remain poorly defined. METHODS: C2C12 myoblasts and primary myoblasts were treated with C18:0 or C24:1 ceramides during differentiation to assess myotube formation, migration and intracellular reactive oxygen species (ROS) levels. Three-month-old C57BL/6 mice received daily intraperitoneal injections of C18:0 or C24:1 ceramides for 4 weeks to evaluate muscle morphology and function. In a human cohort of 165 community-dwelling older adults (≥ 65 years), serum ceramide levels were measured via LC-MS/MS and analysed in relation to sarcopenia parameters. RESULTS: Both C18:0 and C24:1 ceramides significantly impaired myogenic differentiation in vitro, as evidenced by reduced myotube number, total myotube area, average area per myotube, nuclei count per myotube and fusion index, through ROS-mediated mechanisms (with up to an 8.6-fold increase in ROS production). Consistently, C18:0 and C24:1 ceramides markedly downregulated key myogenic markers and inhibited ITGB1-FAK-AKT signalling while promoting nuclear activation of FoxO-associated catabolic pathways. These deleterious effects were attenuated by treatment with the antioxidant N-acetylcysteine. In mice, systemic administration of either ceramide resulted in reduced muscle fibre cross-sectional area in the tibialis anterior (by 20.5% and 20.9% for C18:0 and C24:1, respectively) and soleus muscles (by 18.1% and 16.1%), accompanied by decreased grip strength, shorter grid hanging times and reduced latency to fall in the rotarod test. Clinically, in a cohort of 165 older adults (80.6% female; mean age 75.2 ± 5.2 years in controls and 79.7 ± 4.8 years in the sarcopenia group), serum levels of C18:0 and C24:1 ceramides were 27% and 14% higher, respectively, in individuals with sarcopenia compared to controls (p = 0.001 and 0.018). Furthermore, each standard deviation increase in serum C18:0 and C24:1 ceramide levels was associated with a 2.0- and 1.6-fold increased risk of sarcopenia, respectively (p = 0.003 and 0.040). CONCLUSIONS: Our findings reveal that circulating C18:0 and C24:1 ceramides are significantly associated with sarcopenia in older adults, while experimental models demonstrate they promote muscle atrophy through oxidative stress-induced impairment of myogenesis and muscle function. These ceramides may serve as minimally invasive biomarkers and potential therapeutic targets for age-related muscle decline. Interventions aimed at modulating ceramide metabolism could offer new avenues for sarcopenia prevention and treatment in aging populations.