Construction and Mechanism of IL-15-based Co-Activated Polymeric Micelles for NK Cell Immunotherapy.

Natural killer (NK) cells have emerged as an important contributor to cancer immunotherapy, but their antitumor efficacy remains suboptimal. While cytokine-based priming shows promise in enhancing NK-cell activity, its clinical translation faces many challenges, including co-activation of multiple cytokines, poor pharmacokinetics, and limited mechanistic understanding. Here, we developed a polymeric micelle-based IL-15/IL-2 codelivery system (IL-15/2-PEG-PTMC) for NK-cell activation. In vivo studies demonstrated that the half-life of IL-15 and IL-2 as well as the recruitment of NK cell within tumor tissue was significantly increased after PEG-PTMC loading. Coupled with the coactivation effect of IL-15 and IL-2 conferred by this polymeric micelle-based system, it noticeably delayed the growth of tumors in mice compared to conventional NK cell activation approach, that was free IL-15 and IL-2. We also surprisingly found that cholesterol metabolism was highly involved in the NK cell activation by IL-15/2-PEG-PTMC. Following stimulation with IL-15/2-PEG-PTMC or IL-15, NK cells underwent a series of cholesterol metabolism reprogramming, which elevated the cholesterol levels on the NK cell membrane. This in turn promoted the formation of lipid rafts and actived immune synapse, effectively contributing to the enhancement of the NK cell's anti-tumor activity. We believe this will open a new avenue for improving the efficacy of NK cell immunotherapy by regulating cholesterol metabolism. This article is protected by copyright. All rights reserved.