Chemical modification strategies for photo-induced control of immune cell signaling

Abstract

Abstract Cytokine therapies show great potential to induce cancer immune elimination and have demonstrated therapeutic benefit in a subset of patients. However, controlling the pleotropic effects of these immune signal effectors is a challenge. Here, we present an approach to enable optical control of cytokine activity by caging the activity of these proteins via labeling with wavelength-specific, photo-labile polymers (i.e. photo-caging). We create a system to measure light-induced polymer cleavage (uncaging) through fluorescence dequenching and establish: high wavelength-selectivity, protein activation through tissue mimics, and micrometer-scale uncaging resolution (via photopatterning). We focus on cytokines IL-2, IL-12 and IL-15 and demonstrate ability to reversibly modulate cytokine size and activity. We show photo-caging increases cytokine size by up to 20 fold, resulting in increased serum half-life. Additionally, cytokine activity (via T-cell proliferation) is blunted by 1,000 fold and near fully recovered through light-induced uncaging. Affinity measurements demonstrate photo-caging disrupts the bias of IL-2 towards IL-2Rα expressed on immunosuppressive T-regulatory cells. Further, photo-caging negates the ability of IL-2 to increase antigen specific (OT-1) cell activation, but is restored upon uncaging. In summary, we present the synthesis and therapeutic potential of these optically activated cytokines. In future studies we aim to use cytokine photo-caging as a means to provide new insights into the mechanics of cancer immune elimination and achieve tissue exclusive activation by exploiting spatially and temporally constraining cytokine activation in chip-based organoids and in vivo cancer models.