Immune Modulatory Oxysterols Produced from Cholesterol-Containing Lipid Nanoparticles Regulate Tumor Growth.

Cholesterol is a component of most clinically approved lipid nanoparticles (LNPs) to enhance the stability, fluidity, and organization of the lipid structure. Endogenous cholesterol undergoes oxidation, producing cholesterol oxidation products (oxysterols), which are potent regulators of cellular processes implicated in immune dysfunction and the pathogenesis of cancers. LNP-associated cholesterol (LNP-cholesterol) is internalized by macrophages, and these cells also play critical roles in cholesterol metabolism and regulation of immune responses against cancer. Yet, the metabolic fate of LNP-cholesterol remains unclear. In this work, we elucidated the in vivo metabolic fate of LNP-cholesterol and demonstrated that LNP-oxysterols affect tumor cell proliferation and modulate macrophage functionality, impacting tumor growth in a murine model of cancer. Importantly, we showed that LNP-associated 7α-hydroxycholesterol, 7β-hydroxycholesterol, 24-hydroxycholesterol, and 27-hydroxycholesterol have antitumoral effects, while LNP-associated 7-ketocholesterol and 5,6-epoxycholesterol have protumoral effects, suggesting that cholesterol metabolism and cholesterol analogs can be leveraged to enhance LNP drug efficacy in cancer. Our findings indicate that LNP carriers have an unintended impact on tumor growth, which has the potential to diminish or enhance the anticancer efficacy of LNP-associated therapeutic cargo. Our results highlight the potential to engineer LNP carriers with immune-modulatory activity that combines the advantages of both nanoparticle-mediated drug delivery and immunotherapy.