Single-Site Nanozymes with a Highly Conjugated Coordination Structure for Antitumor Immunotherapy via Cuproptosis and Cascade-Enhanced T Lymphocyte Activity

The extracellular matrix (ECM) in the tumor microenvironment (TME) and upregulated immune checkpoints (ICs) on antitumor immune cells impede the infiltration and killing effect of T cells, creating an immunosuppressive TME. Herein, a cholesterol oxidase (CHO) and lysyl oxidase inhibitor (LOX-IN-3) co-delivery copper-dibenzo-[g,p]chrysene-2,3,6,7,10,11,14,15-octaol single-site nanozyme (Cu-DBCO/CL) was developed. The conjugated organic ligand and well-distributed Cu-O4 sites endow Cu-DBCO with unique redox capabilities, enabling it to catalyze O2 and H2O2 to ·O2- and ·OH. This surge of reactive oxygen species (ROS) leads to impaired mitochondrial function and insufficient ATP supply, impacting the function of copper-transporting ATPase-1 and causing dihydrolipoamide S-acetyltransferase oligomerization-mediated cuproptosis. Moreover, multiple ROS storms and glutathione peroxidase 4 depletion also induce lipid peroxidation and trigger ferroptosis. Simultaneously, the ROS-triggered release of LOX-IN-3 reshapes the ECM by inhibiting lysyl oxidase activity and further enhances the infiltration of cytotoxic T lymphocytes (CD8+ T cells). CHO-triggered cholesterol depletion not only increases ·OH generation but also downregulates the expression of ICs such as PD-1 and TIM-3, restoring the antitumor activity of tumor-infiltrating CD8+ T cells. Therefore, Cu-DBCO/CL exhibits efficient properties in activating a potent antitumor immune response by cascade-enhanced CD8+ T cell viability. More importantly, ECM remodeling and cholesterol depletion could suppress the metastasis and proliferation of the tumor cells. In short, this immune nanoremodeler can greatly enhance the infiltration and antitumor activity of T cells by enhancing tumor immunogenicity, remodeling ECM, and downregulating ICs, thus achieving effective inhibition of tumor growth and metastasis.