Abstract The Program Project will employ in all projects novel engineered reagents that enable manipulation and interrogation of individual signaling pathways with precise spatial and temporal control. As described in individual Projects, reagents provided by Core B will be used to define the signaling processes that regulate plasticity and specialization of macrophages and define their role during lung inflammation and injury as well as resolution. Development and optimization of these tools will require the efforts of the Synthetic Biology and Optogenetics Core B. The central functions of Core B will be 1) to develop molecular tools customized for each specific question in individual Projects, 2) to evaluate the new reagents as they come on-line and establish protocols for their application in macrophages and in in vivo mouse model, and 3) to provide assistance to all Projects with the application of the tools, troubleshooting, and analysis of the results. The intent will be to simplify application of these advances technologies to dissect specific signaling pathways in the Program Project and allow participants to focus on the proposed questions requiring these reagents. The specific tools that will be developed and employed by Core B include: 1) new reagents to control localization and interactions of proteins identified by Projects; and 2) reagents for regulation of activity of selected proteins in living macrophages, and targeted activation of these proteins in specific complexes and subcellular locations. Core B will also generate and optimize reagents for expression of engineered proteins in macrophages and develop new reagents as needed for manipulation and interrogation of protein interactions and cell signaling. The tools developed will enable manipulation of individual signaling pathways, deconstruction of these pathways, and assessment of their roles in the regulating function of macrophages in lungs.