Project Summary This proposal is for a five-year research program for Dr. Jon Wisler, an Assistant Professor in the Division of Trauma, Critical Care, and Burn Surgery. This proposal aims to study the effects of exosome-mediated epigenetic regulation that occurs during sepsis, under the mentorship of Dr. John Christman. Dr. Christman is a highly productive researcher in the fields of monocyte/macrophage biology and epigenetics who has a long track of mentorship and productivity. The research and career development portions of the proposal focus on technique expansion and professional development. This includes a refined, logical plan with measurable short and long-term milestones. Utilizing the extensive experience of his mentorship team, this proposal will train Jon is cutting-edge technologies including CRISPR-gene editing, live-cell imaging, nanoparticle RNA packaging and delivery, and exosome biology to greatly improve his mechanistic understanding and investigatory capabilities. Patients with sepsis exhibit a profound degree of immunosuppression with higher levels of subsequent infectious complications and increased long-term mortality. Our preliminary data identifies significant increases in DNA Methyltransferases (DNMT) mRNAs in circulating exosomes of patients with sepsis, and that this DNMT mRNA is transferred from these exosomes to naïve monocytes. This transfer results in increased epigenetic events (promoter methylation) and gene silencing. Our intent for this application is to elucidate the mechanisms of exosome uptake, and target these epigenetic events in an in vivo model of sepsis. We hypothesize prevention of exosome-mediated DNA methylation allows for maintenance of the host immune response during sepsis. The overall objective is to identify the mechanistic base that underlies exosome-mediated control of the epigenetic events that govern sepsis-related immunosuppression, and identify the potential translational value of targeting DNMT function to treat complications associated with sepsis. Incorporating the training of novel, cutting-edge techniques will greatly improve the Jon's scientific expertise, and allow for the progression from mentored to independent surgeon-scientist. Aim 1: Elucidate the mechanisms that underlie the cellular uptake of exosomes and define the role of DNMT as an epigenetic messenger that contributes to post-sepsis mediated immunosuppression Aim 2: Establish the safety and efficacy of targeting exosome-mediated delivery of anti-DNMT to prevent immunosuppression during sepsis in mouse models