Microfluidic-Assisted Metal-Polyphenol Cloaked Bacteria Enable CRISPR/dCas9-Mediated Pyroptosis Cascade Amplification for Effective Tumor Immunotherapy

Pyroptosis triggered by pore-forming Gasdermin proteins in cancer cells facilitates anti-tumor immune activation by releasing pro-inflammatory cytokines and immunogenic contents following cellular rupture. However, selectively triggering pyroptosis in tumors still remain limited in clinical applications. Here, it is reported a microfluidic-assisted bacterial delivery system using attenuated Salmonella typhimurium VNP20009 encapsulated with metal-phenolic networks composed of ferric ions (Fe 3 + ) and tannic acid (TA) to enhance intracellular gasdermin D (GSDMD) expression through targeted CRISPR/dCas9 delivery, thereby inducing robust tumor pyroptosis. Mechanistically, this system achieves cascade amplification of pyroptotic cell death through coordinated multi-modal mechanisms. Following systemic administration, VNP20009 specifically accumulates in hypoxic tumor regions while the coated Fe 3 + –TA nanofilm undergoes pH-responsive dissolution in the acidic tumor microenvironment (TME), simultaneously generating ROS through Fenton reaction and releasing CRISPR/dCas9 system to upregulate GSDMD expression. Concurrently, the abundant flagella of VNP activate caspase-1, which in turn cleaves the overexpressed GSDMD proteins into its active form, thereby triggering robust pyroptosis in tumor cells. Taken together, by coupling bacterial adjuvanticity with ROS-mediated stress and CRISPR-driven GSDMD upregulation, this strategy achieves efficient amplification of pyroptosis and promotes antitumor immune activation.