Regulatory T cells (Tregs) and plasmacytoid dendritic cells (pDCs) play important roles in the immune escape of cancer. In this study, we investigated pDCs and pDC-induced inducible costimulator (ICOS)+ Treg populations in peripheral blood from gastric cancer (GC) patients and healthy donors by flow cytometry. The distribution of these cells in carcinoma tissue, peritumor tissue, and normal gastric mucosa was detected by immunohistochemistry. Plasma and tissue concentration of the cytokines such as interleukin-10 and transforming growth factor-β1 were also measured. We found that the numbers of pDCs, Tregs, and ICOS+ Tregs in peripheral blood were increased in GC patients compared with healthy donors. In tissue, Tregs and ICOS+ Tregs were found distributing mainly in carcinoma tissue, whereas pDCs were mainly found in peritumor tissue. Moreover, the Foxp3+ICOS+/Foxp3+ cell ratio in carcinoma and peritumor tissue were higher than that in normal tissue. There were more ICOS+ Tregs in tumor and peritumor tissue of late-stage GC patients. There was a positive correlation between pDCs and ICOS+ Tregs in peripheral blood and peritumor tissue from GC patients. In conclusion, pDCs may play a potential role in recruiting ICOS+ Tregs, and both participate in the immunosuppression microenvironment of GC.

Current oxidative stress amplifying strategies for immunogenic cell death (ICD) promotion are mainly restricted to immune tolerance induced by adaptive cellular antioxidation, limited tumor-selectivity, and tumoral immunosuppression. Herein, a facile and efficient scenario of genetically engineering transferrin-expressing cell membrane nanovesicle encapsulated IR820-dihydroartemisinin nanomedicine (Tf@IR820-DHA) was developed to boost a-PD-L1mediated immune checkpoint blocking (ICB) via synergetic triple stimuli-activated oxidative stress-associated ICD. We demonstrate that the engineered transferrin of Tf@IR820-DHA has excellent tumor targeting and Fe(III)-loading properties and thus delivered Fe(III) and IR820-DHA nanoparticles (NPs) to the lesion location effectively. We found that the self-carrying Fe(III)-mediated programmable catalysis of DHA and glutathione (GSH) depletion generated plenty of reactive oxygen species (ROS). Moreover, DHA also acted as an immunomodulator to decrease the number of T regulatory cells, thereby remodeling the tumor immune microenvironment and achieving double T cell activation. Furthermore, the IR820 molecule served as a competent sonosensitizer to produce ROS under ultrasound activation and guide precise immunotherapy via fluorescent/photoacoustic (FL/PA) imaging. Through its three-pronged delivery of stimuli-activated oxidative stress (DHA-induced chemodynamic therapy, catalysis-conferred GSH depletion, and IR820-mediated sonodynamic therapy), Tf@ IR820-DHA caused high levels of targeted ICD. This significantly increased the proportions of IFN-γ-secreting T cells (CD4 + T and CD8 + T) and enhanced a-PD-L1-mediated ICB against primary and distant tumors, which represents a promising approach for cancer nanoimmunotherapy.

The combination of chemotherapy and immunotherapy motivates a potent immune system by triggering immunogenic cell death (ICD), showing great potential in inhibiting tumor growth and improving the immunosuppressive tumor microenvironment (ITM). However, the therapeutic effectiveness has been restricted by inferior drug bioavailability. Herein, we reported a universal bioresponsive doxorubicin (DOX)-based nanogel to achieve tumor-specific co-delivery of drugs. DOX-based mannose nanogels (DM NGs) was designed and choosed as an example to elucidate the mechanism of combined chemo-immunotherapy. As expected, the DM NGs exhibited prominent micellar stability, selective drug release and prolonged survival time, benefited from the enhanced tumor permeability and prolonged blood circulation. We discovered that the DOX delivered by DM NGs could induce powerful anti-tumor immune response facilitated by promoting ICD. Meanwhile, the released mannose from DM NGs was proved as a powerful and synergetic treatment for breast cancer in vitro and in vivo , via damaging the glucose metabolism in glycolysis and the tricarboxylic acid cycle. Overall, the regulation of tumor microenvironment with DOX-based nanogel is expected to be an effectual candidate strategy to overcome the current limitations of ICD-based immunotherapy, offering a paradigm for the exploitation of immunomodulatory nanomedicines.

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