Figure 5: A schematic representation for the effect of 4-1BB/4-1BBL interaction on skeletal muscle inflammation. Obesity induces upregulation of 4-1BB on skeletal muscle cells, which interacts with its ligand 4-1BBL expressed on infiltrated macrophages. This interaction triggers bidirectional inflammatory signaling into both cells, leading to exacerbation of inflammatory responses and metabolic dysfunction in skeletal muscle.