In situ delivery of mRNA-encoded Gasdermin E promotes antitumor immunity via creatine-elicited type ? interferon signaling in monocytes

Tumor microenvironment is highly immunosuppressive. Tumor immunotherapy aims to reverse the immunosuppressive tumor microenvironment, activating antitumor immune response, which becomes a hotspot in tumor therapy. mRNA lipid nanoparticle based gene therapy represents a promising strategy for tumor immunotherapy. Identifying novel mRNA target is critical for improving the effect of in vivo gene immunotherapy for cancer. Pyroptosis obtains the key characteristics of immunologic cell death, and GSDME is an essential effector molecule triggering pyroptosis. Here, we synthetized mRNA encoding GSDME encapsulated by LNP (LNP-Gsdme). In situ delivery of LNP-Gsdme through intratumoral injection suppressed tumor growth, boosting monocytes infiltration and CD8+ T cell activation. Mechanistically, LNP-Gsdme-induced pyroptosis and immunogenic cell death in tumor cells, releasing creatine as a novel metabolic damage associated molecular pattern as well as a metabolite biomarker of ICD, eliciting cGAMP-STING-TBK1-IRF3-IFN-I signaling pathway in monocytes, then activating CD8+ T cells in the tumor microenvironment. Furthermore, creatine synergized the antitumor efficacy of LNP-Gsdme. Our observations in this study elucidate the effect and mechanisms of LNP-Gsdme in reshaping tumor immune microenvironment, providing novel insights and therapeutic approach into cancer therapy. Overall design: To explore the underlying mechanisms of the tumor immune microenvironment reshaping after LNP-Gsdme treatment, CD11b+ Ly6Chi Ly6G- monocytes were sorted from B16F10-mCherry tumor models. RNA sequencing was performed to unveil the global changes of gene expression and functional status of tumor-infiltrating monocytes after LNP-Gsdme treatment.