Abstract
Tumor-associated macrophages (TAMs) exist in multiple phenotypes across the spectrum, defined by an M1 antitumorigenic phenotype and an M2 pro-tumorigenic phenotype on two ends of the spectrum. A largely immunosuppressive tumor-microenvironment aids the polarization of the infiltrating macrophages to a pro-tumorigenic M2 phenotype that promotes tumor progression and metastasis. Recent developments in macrophage immunotherapy have focused on strategies to re-educate TAMs from an M2 to M1 phenotype. Recent findings in the realm of immuno-metabolism have indicated that distinct metabolic signatures accompany macrophages based on their polarization states (M1-Glycolysis and M2-TCA cycle). These metabolites are important drivers of cellular signaling responsible for acquiring these polarization states, with evidence showing that metabolism is essential to facilitate the energy requirements of immune cells and regulate immune cell response. We hypothesized that TAMs could be reprogrammed metabolically by co-delivery of drugs using a supramolecular nanoparticle system that could effectively rewire macrophage metabolism by simultaneous inhibition of the TCA cycle and upregulation of the glycolytic metabolic pathway. TLR7/8 agonist and Fatty Acid Oxidation (FAO) inhibitor loaded metabolic supramolecular nanoparticles (MSNPs) were synthesized. In vitro assays showed macrophages treated with MSNPs were reprogrammed from an M2 phenotype to an M1 phenotype while significantly upregulating phagocytosis. When injected in 4T1 tumor-bearing mice, MSNPs treatment reduced tumor growth progression more than other treatments. Hence, the delivery of TLR7/8 agonist combined with an FAO inhibitor can enhance antitumor efficacy through metabolic reprogramming of tumor-associated macrophages.