(126f) Rewiring Intracellular Signaling Pathways to Probe the Robustness of Innate Immune Cell Decision Making

Leonard, J. N. - Presenter, Northwestern University

The goal of this project is to investigate how innate immune cells process disparate extracellular stimuli via intracellular signaling pathways to arrive at a coherent response and determine whether signal rewiring can affect this response. In particular, innate immune cells such as dendritic cells and macrophages may become functionally polarized towards either immunostimulatory or immunosuppressive phenotypes, a process that plays an important role in controlling local immune responses during many chronic diseases. However, the regulation of this decision point is poorly understood. In the case of cancer, signals within the tumor microenvironment induce local immune dysfunction, which causes responding immune cells to promote tumor growth rather than tumor destruction and clearance. It has been reported that the influence of such immunosuppressive stimuli can be overridden by intratumoral injection of immunostimulatory ligands such as Interleukin 12 (IL-12) or agonists for the Toll-like Receptors (TLRs), which induce potent immune activation in response to pathogen associated molecules.

In order to probe the robustness of innate immune cell decision making in response to contradictory intracellular signaling, we constructed a library of receptors that rewire various polarization-related intracellular signaling pathways in macrophages and dendritic cells. We hypothesize that some types of rewiring may be sufficient to fully invert the response of a cell to a given microenvironment. In particular, we sought to identify a rewiring strategy that would invert the response of an innate immune cell to a tumor-associated immune microenvironment, since such an approach may be of therapeutic relevance to the treatment of cancer. Top-down and bottom-up rewiring strategies were included in the construction of this library, meaning that rewiring was accomplished both through the use of chimeric receptors that integrate with native signaling pathways and orthogonal sensors and signaling pathways. We will describe the use of this library to probe the robustness of innate immune cell polarization and re-polarization in tumor-associated immune microenvironments.