PROJECT ABSTRACT Small molecule and protein signals provide a rich vocabulary for cellular communication. The production and consequences of these signals are exquisitely sensitive to cellular context and microenvironment. Dissecting the molecular dialogue between cell types is challenging, and new methods are required to address fundamental questions: What is the downstream biological function of each signaling molecule? How is the biological function different when molecules are present in mixtures or when different cell types are present in the microenvironment? How do microbes—like the bacteria and fungi present in our bodies—affect the molecular landscape? Our lab is developing new tools to probe these questions including (1) microscale co- and multiculture methods that enable precise positioning of cell types to study cell signaling, (2) specialized culture platforms for complex human-bacteria-fungal multikingdom culture, (3) integration of microbial co- and multiculture systems with volatile organic compound (VOC) sampling to study how volatiles mediate microbial dialogue, and (4) at-home biofluid sampling and stabilization platforms to probe the human immune response over time. The present proposal expands our lab’s capabilities in areas (1) and (3), with the possibility to extend to (2) and (4) in future work. This proposal will probe unanswered questions in two areas of human cell signaling: (i) paracrine signaling between eosinophils and fibroblasts and (ii) paracrine/physical contact-mediated signaling between neutrophils, monocytes, and B cells. Further, we will develop novel culture platforms that enable microbial and multikingdom (e.g., bacteria, fungi) VOC communication and integrated sampling for gas chromatography-mass spectrometry (GC-MS) analysis. This culture system will, for the first time, enable controlled spatial positioning of multiple microbial cultures, a user-friendly setup that can be operated with simple pipettes, fluidic channels to deliver media and chemical stimulation, and integration of solid phase micoextraction (SPME) fibers for VOC sample collection. Central to this proposal is the use of ‘open’ microfluidics and spontaneous capillary flow. We are leaders in open microfluidics and have a strong track record of developing user-friendly, cost-effective methods to perform microscale multiculture experiments within standard well plates and cultureware familiar to biologists. The proposed work builds on our capabilities and embraces significant engineering challenges in doing triculture with sensitive primary cells and innovating an entirely new approach for study VOCs in microbial cultures. The proposed methods will enhance the understanding of the signals involved in detrimental prolonged inflammation, critical to the development of better therapies for numerous inflammatory conditions; they will also enable study of microbial communities that are essential to maintaining human health (commensal microbes) and t...