Intravenous Delivery of Living <i>Listeria monocytogenes</i> Elicits Gasdmermin-Dependent Tumor Pyroptosis and Motivates Anti-Tumor Immune Response.

Abstract

The facultative intracellular bacterium <i>Listeria monocytogenes</i> (<i>Lmo</i>) has great potential for development as a cancer vaccine platform given its properties. However, the clinical application of <i>Lmo</i> has been severely restricted due to its rapid clearance, compromised immune response in tumors, and inevitable side effects such as severe systemic inflammation after intravenous administration. Herein, an immunotherapy system was developed on the basis of natural red blood cell (RBC) membranes encapsulated <i>Lmo</i> with selective deletion of virulence factors (<i>Lmo</i>@RBC). The biomimetic <i>Lmo</i>@RBC not only generated a low systemic inflammatory response but also enhanced the accumulation in tumors due to the long blood circulation and tumor hypoxic microenvironment favoring anaerobic <i>Lmo</i> colonization. After genome screening of tumors treated with intravenous PBS, <i>Lmo</i>, or <i>Lmo</i>@RBC, it was first found that <i>Lmo</i>@RBC induced extensive pore-forming protein gasdermin C (<i>GSDMC</i>)-dependent pyroptosis, which reversed immunosuppressive tumor microenvironment and promoted a systemic strong and durable anti-tumor immune response, resulting in an excellent therapeutic effect on solid tumors and tumor metastasis. Overall, <i>Lmo</i>@RBC, as an intravenous living bacterial therapy for the selective initiation of tumor pyrolysis, provided a proof-of-concept of live bacteria vaccine potentiating tumor immune therapy.