TGF-ß1 mediates tumor immunosuppression aggravating at the late stage post-high-light-dose photodynamic therapy.

Photodynamic therapy (PDT) is an emerging clinical treatment that is expected to become an important adjuvant strategy for the immunotherapeutic cancer treatment. Recently, numerous works have reported combination strategies. However, clinical data showed that the anti-tumor immune response of PDT was not lasting though existing. The immune activation effect will eventually turn to immunosuppressive effect and get aggravated at the late stage post-PDT. So far, the mechanism is still unclear, which limits the design of specific correction strategies and further development of PDT. Several lines of evidence suggest a role for TGF-ß1 in the immunosuppression associated with PDT. Herein, this study systematically illustrated the dynamic changes of immune states post-PDT within the tumor microenvironment. The results clearly demonstrated that high-light-dose PDT, as a therapeutic dose, induced early immune activation followed by late immunosuppression, which was mediated by the activated TGF-ß1 upregulation. Then, the mechanism of PDT-induced TGF-ß1 accumulation and immunosuppression was elucidated, including the ROS/TGF-ß1/MMP-9 positive feedback loop and CD44-mediated local amplification, which was further confirmed by spatial transcriptomics, as well as by the extensive immune inhibitory effect of local high concentration of TGF-ß1. Finally, a TGF-ß blockade treatment strategy was presented as a promising combinational strategy to reverse high-light-dose PDT-associated immunosuppression. The results of this study provide new insights for the biology mechanism and smart improvement approaches to enhance tumor photodynamic immunotherapy.

Confined Target-Triggered Hot Spots for In Situ SERS Analysis of Intranuclear Genotoxic Markers.

The γH2AX is a type of confined target in nuclei which is highly expressed around the damaged DNA during genotoxicity and has therefore been identified as a marker of genotoxicity. Convenient and intuitive in situ real-time detection of γH2AX is crucial for an accurate assessment of genotoxicity. Selective and nondestructive surface-enhanced Raman spectroscopy (SERS) is suitable to achieve this goal. However, the detection of substances in the nucleus by SERS is still limited due to the contradiction of probes between the nuclei entry efficiency and signal enhancement. This study utilized the characteristics of γH2AX as a confined target and constructed a γH2AX immunosensor based on gold nanoprobes with a small size (15 nm), which was modified with the TAT nuclear targeting peptide to ensure high nuclei entry efficiency. Once DNA damage was induced, the local overexpression of γH2AX further recruited the probe through immune recognition, so that hot spots could be assembled in situ to generate strong Raman signals, which were applied to evaluate the genotoxicity of drug impurities. This study proposed a novel SERS detection strategy, characterized by confined target-induced size conversion and hot spot formation, for in situ real-time analysis of intranuclear targets at the single-living-cell level, which intelligently simplified the structure of SERS probes and the operation process.