PROJECT SUMMARY The etiology of Barrett's esophagus (BE), a complex metaplastic disorder of the distal esophagus, remains elusive. Patients with BE are at an increased risk of developing esophageal adenocarcinoma (EAC), a lethal, and increasingly prevalent disease, and the most common esophageal malignancy in the U.S. Our long-term objective is to identify the causative mechanisms underlying the onset and malignant progression of BE, and to develop evidence-based biomarkers and chemopreventive/therapeutic strategies for subsequent clinical intervention. Project 2 of this program addresses a controversial area in the field that has been understudied. Esophageal submucosal glands (ESMGs) represent a progenitor cell source in the esophagus and our group has previously demonstrated increased proliferation and acinar ductal metaplasia (ADM) in ESMGs in the context of injury and EAC. We have observed immune cell infiltrates in ESMGs associated with ADM, but important knowledge gaps persist about the types of immune cells found in areas of ADM and the effect of this microenvironment on ADM, wound healing, and the molecular programs associated with BE/EAC. Project 2 will thus investigate the relationship between injury-induced cytokines such as C-X-C motif chemokine ligand 8 (CXCL8 or IL8)), esophageal wound healing, and ADM. Ongoing inflammation and abnormal signaling in ESMGs and at the GEJ may provide a persistent source of abnormal progenitor cells after radiofrequency ablation, contributing to treatment failures including refractory and recurrent dysplasia and progression to EAC. The proposed project will address preclinical questions about how to improve outcomes after radiofrequency ablation or endoscopic resection of early lesions, including high grade dysplasia and very early cancers. To address these research questions, we will use our 1) large human esophagectomy database that includes failed- radiofrequency ablation cases that resulted in esophagectomy, and 2) our porcine radiofrequency ablation model and porcine and patient-derived organoids. Our project has strong synergy with both projects 1 and 3, expanding the scope our program project grant to include models with ESMGs and allowing comparison to wound healing at the gastroesophageal junction. We will investigate how targeting the inflammation in ESMGs and at the gastroesophageal junction may provide a potential cancer interception and preventive strategies. .