Enhancement of antibiotic therapy in osteomyelitis by inhibiting talin-1-mediated bacterial internalization

Intracellular infection by Staphylococcus aureus (S. aureus) is a major driver of persistent osteomyelitis, leading to antibiotic failure and recurrent bone destruction. However, the precise host-pathogen interactions and mechanisms underlying bacterial internalization remain incompletely understood. In this study, we employed an in vitro intracellular infection model using bone marrow mesenchymal stem cells alongside an in vivo murine osteomyelitis model. Integrated multi-omics, structure-guided molecular docking, and mutation analyses revealed that S. aureus promotes the physical recruitment of the host adapter Mprip specifically to the Talin-1 D125 residue. This structural binding triggers the subsequent Talin-1 phosphorylation cascade, which exerts a dual pathological effect: facilitating extensive bacterial internalization and suppressing osteogenic recovery via the PI3K/AKT pathway. Genetic deletion of Mprip or Talin-1 markedly reduced the bacterial burden and restored osteogenesis. Furthermore, through structure-based virtual screening targeting the binding interface at residue D125, we identified a specific small molecule, UM-164. UM-164 effectively disrupted the Mprip/Talin-1 interaction and blocked subsequent Talin-1 phosphorylation. By effectively inhibiting bacterial internalization, UM-164 restricted bacteria to the extracellular space, thereby synergizing with systemic gentamicin to reduce the overall bacterial burden and mitigate bone destruction in vivo. In conclusion, the structural binding of Mprip to Talin-1 and the resulting phosphorylation cascade drive S. aureus osteomyelitis through a dual mechanism of bacterial internalization and PI3K/AKT-mediated osteogenic suppression. UM-164, a small molecule specifically screened to target the Mprip/Talin-1 D125 interface, presents a potent host-directed strategy to prevent bacterial internalization and potentiate antibiotic efficacy in recalcitrant bone infections.