Inhibition of TWEAK/Fn14 Ameliorates Sarcopenic Obesity by Restoring Mitochondrial Biogenesis via the AMPK/SIRT1/PGC-1α Axis

Purpose: Sarcopenic obesity (SO) represents a critical geriatric syndrome where muscle atrophy and obesity synergistically exacerbate metabolic dysfunction. While the TWEAK/Fn14 pathway is a known regulator of muscle wasting, its specific role and therapeutic potential in the pathogenesis of SO remain unclear. Methods: To mimic the lipid-rich microenvironment of SO, we utilized a "PrePA-Diff" in vitro model where C2C12 myoblasts were exposed to palmitic acid prior to differentiation. In vivo, SO was established by feeding aged (18-month-old) male C57BL/6 mice a high-fat diet (HFD) for 12 weeks. Subsequently, intramuscular injection of Adeno-associated virus (AAV)-shRNA was employed to specifically inhibit TWEAK expression in skeletal muscle. Mitochondrial function, inflammatory profiles, and signaling pathways were assessed using qPCR, Western blotting, ELISA, and functional assays. Results: Our results demonstrate that TWEAK inhibition effectively reverses the SO phenotype, characterized by improved grip strength, reduced adiposity, and lowered systemic inflammation and lipid levels. At the cellular level, TWEAK silencing rescued mitochondrial bioenergetics, indicated by enhanced ATP production and suppressed reactive oxygen species (ROS) generation and calcium influx. Molecularly, these protective effects were accompanied by the downregulation of p38 MAPK phosphorylation and the reactivation of the AMPK/SIRT1/PGC-1α signaling axis, a key driver of mitochondrial biogenesis. Conclusion: Our study identifies the TWEAK/Fn14 axis as a pivotal driver of SO pathology. We conclude that inhibiting TWEAK ameliorates sarcopenic obesity by restoring mitochondrial homeostasis via AMPK/SIRT1/PGC-1α signaling, highlighting TWEAK/Fn14 as a novel therapeutic target for age-related musculoskeletal and metabolic decline.