LIFUS-Driven Engineered Bacteria Reprogram Immunosuppressive Niches via Mechano-NOTCH Signaling

The tumor microenvironment (TME) of solid tumors constructs a complex biophysical barrier with intricate interactions, including dense stromal structures and immunosuppressive networks, which severely limit the permeability and efficacy of immunotherapy. This study developed an engineered an attenuated Salmonella typhimurium VNP20009 strain encoding an acoustic reporter gene (ARG)-based gas vesicles (GVs), enabling real-time tumor imaging guided mechano-immunomodulation. Low-intensity focused ultrasound (LIFUS) triggered cavitation effects from GVs, generating localized shear forces and mechanical strain. This significantly inhibited tumor growth and attenuated the NOTCH-mediated crosstalk between cancer-associated fibroblasts (CAFs) and CD8⁺ T cells, thereby relieving CD8⁺ T cell activity. This mechanobiological intervention elicited a 12-fold enhancement in cytotoxic CD8⁺ T cell infiltration and extended median survival to over 60 days (versus 30-40 days in controls) in aggressive murine tumor models, demonstrating significant therapeutic efficacy. This integrated strategy establishes a closed-loop therapeutic platform combining bacterial targeting, acoustic visualization, and LIFUS-driven mechano-immunomodulation, achieving 92.7% suppression of both primary and metastatic tumor growth. By synergizing synthetic biology with mechano-immunological regulation, our study pioneers a precisely controllable and real-time image-monitored therapeutic paradigm, providing a transformative approach to overcome solid tumor resistance and accelerate clinical translation.