Macrophage Immunotherapy with Recombinant Cytokines that are Immobilized on Synthetic Nanogel Substrates

Abstract

Cytokines are potent endogenous modulators of innate immunity, making them key mediators of macrophage plasticity for immunotherapy. However, the clinical translation of recombinant cytokines as therapeutics is limited by systemic side effects, caused by cytokines’ pleiotropy, potency, and non-specific biodistribution following systemic dosing. We developed a cytokine delivery platform utilizing poly(acrylamide-co-methacrylic acid) synthetic nanogels as a biodegradable synthetic substrate for conjugated recombinant cytokines (i.e., IFNγ, IL4, or IL10), called Synthetic Nano-CytoKines or “SyNK”. We evaluated the phenotypic response of macrophages to these conjugates following prophylactic or therapeutic dosing, in the presence or absence of soluble inflammatory signals. Our data confirmed that SyNK is highly cytocompatible with murine macrophages, preserves the activity of conjugated recombinant cytokines, and minimizes systemic exposure to freely soluble recombinant cytokines. Intrinsic activity of the nanomaterial was modest, acting in combination with the conjugated cytokine, and resulted in unique phenotypes with IL4-SyNK and IL10-SyNK stimulation that could potentially be leveraged for therapeutic applications. We further demonstrated that RAW264.7 macrophages adopt distinct alternative phenotypes upon IL4 or IL10 stimulation in different classically polarizing microenvironments, as measured by spectral flow cytometry and secretome multiplex, which are similar for soluble recombinant cytokine and the corresponding SyNK. These findings offer a potential mechanism through which IL4 or IL10-SyNK can redirect the classically activated macrophage antigen presentation, T cell co-stimulation, or microenvironment regulatory functions for therapeutic purposes.

Keywords: nanogel, cytokine, macrophage, immunotherapy, bioconjugation