Escude, M. | bioRxiv Science

bioRxiv2024

Second generation of LNP based mRNA vaccine leads to a T-cell-inflamed tumor microenvironment favorable for improving PD-1/PD-L1 blocking therapy and long-term immunity in a cold tumor model

The delivery of mRNA-based cancer vaccines has demonstrated significant promise in triggering antitumor immune responses. With the aim of using them in combination with other immunotherapies already used in the clinical appropriately, the modifications of the intratumoral immune microenvironment needs to be deeply characterized. We have shown that the second generation of lipid nanoparticles (LNPs), nanostructured lipid carriers (so-called Lipidots(R)), are able to vector protein antigens and nucleic acids. Here, we test Lipidots(R) for the delivery of mRNA encoding OVA antigen and eliciting a specific antitumor immune response. We demonstrate in vitro that our LNPs deliver mRNA into dendritic cells (DCs), when complexed with mRNA, activate DCs through the TLR4/8 and ROS signaling pathways and induce specific CD4+ and CD8+ T cell activation. Our vaccinal strategy exhibits significant antitumor efficacy both in the context of tumor prevention and as a therapeutic vaccine in B16OVA and E.G7-OVA cold tumors. The LNP-Ova mRNA vaccine induces a profound intratumoral remodeling of the innate and adaptive immunity associated with an increase in the gene expression of chemokines (Cxcl10, Cxcl11, Cxcl9) involved in CD8+ T cell attraction. Additionally, the vaccine induces the establishment of an escape mechanism mediated by PD-1/PDL-1 axis, making it an adjuvant therapy for optimized responses to the blocking of this signaling pathway. Finally, the combination of vaccine and anti-PD-1 therapy achieves a much higher rate of complete responses and memory immune responses compared to monotherapies. Our work demonstrates the capability of Lipidots(R) as an effective platform for the development of preventive and therapeutic vaccines against cancer based on mRNA delivery and that combination with other immunotherapies such as immune checkpoint blockers could counter tumor resistance and promote long-term antitumor immunity.

immunology↗

bioRxiv2021

Tuning the immunostimulation properties of cationic lipid nanocarriers for nucleic acid delivery

Nonviral systems, such as lipid nanoparticles, have emerged as reliable methods to enable nucleic acid intracellular delivery. The use of cationic lipids in various formulations of lipid nanoparticles enables the formation of complexes with nucleic acid cargo and facilitates their uptake by target cells. However, due to their small size and highly charged nature, these nanocarrier systems can interact in vivo with antigen-presenting cells (APCs), such as dendritic cells (DCs) and macrophages. As this might prove to be a safety concern for developing therapies based on lipid nanocarriers, we sought to understand how they could affect the physiology of APCs. In the present study, we investigate the cellular and metabolic response of primary macrophages or DCs exposed to the neutral or cationic variant of the same lipid nanoparticle formulation. We demonstrate that macrophages are the cells affected most significantly and that the cationic nanocarrier has a substantial impact on their physiology, depending on the positive surface charge. Our study provides a first model explaining the impact of charged lipid materials on immune cells and demonstrates that the primary adverse effects observed can be prevented by fine-tuning the load of nucleic acid cargo. Finally, we bring rationale to calibrate the nucleic acid load of cationic lipid nanocarriers depending on whether immunostimulation is desirable with the intended therapeutic application, for instance, gene delivery or messenger RNA vaccines.

immunology↗