Engineered bacterial outer membrane vesicles enhanced tumor immunotherapy through remodeling tumor stroma and targeted delivery of CD73 siRNA.

Abstract

The dense, hyaluronic acid (HA)-rich extracellular matrix (ECM) within tumor microenvironment (TME) acts as a physical barrier to therapeutic agents and limits immune cell infiltration. Concurrently, the hypoxic condition of TME activates CD73-adenosine axis, which promotes tumor angiogenesis and metastasis. Here, a potent tumor immunotherapy platform based on genetically and chemically engineered bacterial outer membrane vesicles (OMV) expressing hyaluronidase (HAase) is designed for the targeted delivery of CD73 siRNA (siCD73). This strategy enables initial degradation of HA-rich ECM, thereby enhancing deep tumor penetration and promoting drug retention. Surface modification of OMV with 3-aminophenylboronic acid (PBA) further facilitates sialic acid-mediated tumor targeting and lysosome escape, resulting in a 4.6-fold CD73 inhibition, which suppresses tumor cell and cancer-associated fibroblasts (CAFs) migration, invasion, and adhesion by downregulating epidermal growth factor receptor, matrix metalloproteinase (MMP2/9), and vascular endothelial growth factor (VEGF) secretion. Furthermore, HAase-dependent ECM degradation alleviates deep tumor hypoxia, and inhibits CAFs activation, stromal deposition and angiogenesis by decimating transforming growth factor-β and VEGF secretion, while the intrinsic immunostimulatory properties of OMV leads to more intensive anti-tumor M1 macrophage polarization, dendritic cell maturation, and natural killer cell and cytotoxic T cell infiltration. By comprehensively reprogramming the immunosuppressive TME, the engineered OMV platform demonstrated excellent therapeutic efficacy against primary, recurrent, and metastatic tumors.