Development of Itaconate Polymers Microparticles for Intracellular Regulation of Pro-Inflammatory Macrophage Activation

Abstract

Itaconate (IA) is an endogenous metabolite and a potent regulator of the innate immune system. It's use in immunomodulatory therapies has faced limitations due to challenges in controlled delivery and requirements of high extracellular concentrations for internalization of the highly polar small molecule to achieve its intracellular therapeutic activity. Microparticle (MP)-based delivery strategies are a promising approach for intracellular delivery of small molecule metabolites through macrophage phagocytosis and subsequent intracellular polymer degradation-based delivery. Toward the goal of intracellular delivery of IA, degradable polyester polymer- (poly(dodecyl itaconate)) based IA polymer microparticles (IA-MPs) are generated using an emulsion method, forming micron-scale (≈1.5 µm) degradable microspheres. IA-MPs are characterized with respect to their material properties and IA release kinetics to inform particle fabrication. Treatment of murine bone marrow-derived macrophages with an optimized particle concentration of 0.1 mg million⁻¹ cells enables phagocytosis-mediated internalization and low levels of cytotoxicity. Flow cytometry demonstrates IA-MP-specific regulation of IA-sensitive inflammatory targets. Metabolic analyses demonstrate that IA-MP internalization inhibits oxidative metabolism and induced glycolytic reliance, consistent with the established mechanism of IA-associated inhibition of succinate dehydrogenase. This development of IA-based polymer microparticles provides a basis for additional innovative metabolite-based microparticle drug delivery systems for the treatment of inflammatory disease.