Tumor microenvironment responsive nano-immunoregulator for precision cancer photodynamic immunotherapy

Spatiotemporally controlled reactive oxygen species (ROS) generation remains pivotal for advancing photodynamic immunotherapy. Herein, we present tumor microenvironment (TME)-responsive nano-immunoregulator featuring a CaCO3 shell encapsulating a mesoporous silica core modified with folic acid/chlorin e6 (FA/Ce6) and co-loaded with dBET6 and maleimide (MA). Acidic TME triggers CaCO3 shell degradation, neutralizing tumor acidity to repolarize macrophages toward M1 type, enhancing antigen presentation and T cells immune response while exposing the BM@MFC core. The resulting BM@MFC further endocytosed by tumor cells via FA-mediated tumor targeting, followed by MA-mediated glutathione depletion amplifies Ce6-generated ROS for potent photodynamic therapy (PDT). Concurrently, dBET6 degrades BRD4 to inhibit metastasis, downregulate PD-L1, and synergize with PDT to induce immunogenic cell apoptosis, thereby activating dendritic cells (DCs) and T cells for enhanced photodynamic immunotherapy. Both in vitro/vivo results indicate that BM@MFCC have excellent performance to inhibit primary/metastatic tumors, while single-cell RNA sequencing elucidates BM@MFCC can induce immunosuppressive TME remodeling, including increased CD8+ T cells, cDCs, and NK cells; M2-to-M1 macrophage polarization; and enhanced intercellular communication. Tumor cell profiling confirms BM@MFCC will downregulate oncogenic pathways and activate immune signatures. Collectively, this TME responsive nano-immunoregulator demonstrates superior therapeutic outcomes and provides a promising strategy for precision cancer photodynamic immunotherapy.