Regulation of signaling pathways mediating epithelial cell injury in the neonatal intestine

PROJECT SUMMARY/ABSTRACT Necrotizing enterocolitis (NEC) is a devastating, rapidly progressive gastrointestinal disease of prematurity that affects ~10% of neonates born at < 1500 grams. The risk of NEC is highest for the most preterm neonates, and one infant dies from NEC in the United States each day. The mortality rate for NEC approaches 50% if surgical resection of necrotic bowel is required. Intestinal injury in NEC results from a dysregulated cycle of unrestrained inflammation and intestinal epithelial cell damage. Despite four decades of research, outcomes have not improved for neonates with NEC due to critical knowledge gaps in our understanding of mechanisms underlying disease pathogenesis. The studies outlined in this proposal will characterize new signaling mechanisms regulating intestinal epithelial injury in NEC, determine how these pathways are modulated by microbial metabolites, and use this knowledge to identify new dietary strategies or therapeutic targets. Our laboratory found that activation of the aryl hydrocarbon receptor (AhR) by the dietary ligand indole-3-carbinol (I3C) downregulates the expression of inflammatory cytokines and reduces intestinal injury during experimental NEC. We will now advance our understanding of the anti-inflammatory signaling pathways in the neonatal intestine by examining a pathway closely related to AhR characterized by activation of the transcription factor nuclear factor erythroid 2-related factor 2 (Nrf2). In adult murine colitis models, Nrf2 agonists attenuate intestinal injury. Similarly, our preliminary data reveal that dietary Nrf2 agonist administration reduces inflammation in our murine model of NEC and our unique and innovative microfluidic model incorporating patient-derived intestinal epithelial cells and microbiome. Based on our preliminary data and the published literature, we hypothesize that intestinal epithelial injury will be (1) exaggerated in the absence of Nrf2 signaling in intestinal epithelial cells, (2) downregulated by Nrf2 agonist production by intestinal microbes, and (3) significantly attenuated by therapeutic agents activating the Nrf2 pathway. For these studies, we will utilize specialized genetically modified strains of mice, a humanized NEC model, and our microfluidic model incorporating human neonatal intestinal epithelium. The K08 candidate is a neonatologist-scientist who has transitioned her research focus to intestinal epithelial cell biology and host-pathogen interactions in the developing intestinal tract. Her mentor, Dr. Misty Good, is an international expert in this field and is completely dedicated to the candidate’s success. The extensive training plan outlined in his proposal will facilitate the achievement of her goal of leading an R01- funded laboratory dedicated to improving the health of vulnerable neonates through research focused on intestinal biology and the pathophysiology of NEC.