A Highly Efficient Pyroptosis Activator for Three-Photon Fluorescence Imaging-Guided Phototherapy and Hypoxia Tumor Immunotherapy

Pyroptosis is a highly immunogenic form of programmed cell death capable of eliciting inflammation and enhancing antitumor immune responses. However, there remains a lack of effective visualization of pyroptosis processes and deep-penetrating organelle-targeted photosensitizers in cancer treatment strategies. Here, we develop two aggregation-induced emission (AIE) pyroptosis inducers (CM1-NIC@F127 and CM2-NIC@F127), which are found to proficiently generate reactive nitrogen species (RNS) under hypoxic tumor conditions. The visualization of cellular mitochondrial swelling and the formation of large vesicles throughout the pyroptosis process are achieved owing to their excellent three-photon fluorescence (3PF) properties. Mechanistically, the mitochondria experience dysfunction after phototherapy treatment because of their hypersensitivity to free radical active substances. Cleaved-caspase 1 activation is observed during pyroptosis, leading to the gasdermin D (GSDMD) cleavage fragment GSDMD-N and initiating an inflammatory response. CM1-NIC@F127 promotes dendritic cell (DC) maturation and cytotoxic T cell activation due to the enhanced immunogenic cell death (ICD) effect, leading to the inhibition of both primary and distant tumor growth. Thus, this study provides ideas and strategies for tumor immunotherapy mediated by RNS-induced pyroptosis that has a good therapeutic effect on tumors.