UC San Diego

Eosinophilic Esophagitis (EoE) is an allergic/immune disease of the esophagus that is triggered by food or airborne allergens that invade and damage the esophagus and is distinguished by abnormal presence of eosinophils in the esophagus. This invasion can activate the epithelial layers of the esophagus to initiate a cascade of damaging immune responses and cause inflammation. Chronic inflammation and eosinophil persistence can lead to fibrosis and eventual remodeling of the esophagus that becomes stiff and responds poorly to current therapeutics. This process of remodeling is still not well understood, so we aimed to uncover how the esophageal extracellular matrix environment may contribute to remodeling. It was hypothesized that the extracellular matrix (ECM) is able to alter esophageal fibroblast function. Primary healthy donor fibroblasts (n=5) and EoE active patient fibroblasts (n=5) were decellularized (20mM NH4OH) to create an in culture ECM. Fibroblasts were then reseeded onto these decellularized ECMs. Proteomics analysis was performed on healthy and EoE decellularized ECMs. Once thrombospondin-1 (THBS1) was identified as a unique protein in EoE ECM in proteomics, recombinant human THBS1 was used to treat healthy and EoE fibroblasts to determine whether THBS1 was sufficient to induce fibrotic protein expression. Between 5 different experiments, EoE ECM induces collagen1α1 (2.5 fold, p<0.005) and a-smooth muscle actin (aSMA) (2 fold, p=0.06) protein expression in healthy fibroblasts compared to healthy (NL) ECM. Proteomics illustrates thrombospondin-1(THBS1) as a unique protein to EoE ECMs (fold change > 1.2, p≤0.05) as well as increased expression of Protein disulfide isomerase A6 (PDIA6) in EoE ECM compared to healthy ECM. THBS1 expression is expressed more in ex vivo biopsy samples between biopsies from active state versus inactive state EoE patients (p=0.05). THBS1 also specifically induces collagen1a1 within healthy and EoE primary fibroblasts in a dose response, with significant induction at 10ng/mL (p=0.04). A disintegrin and metalloproteinase with thrombospondin motifs-1 (ADAMTS1) and tissue inhibitor of metalloproteinase 3 (TIMP3) proteins were identified in esophageal fibroblasts to determine any upstream targets of THBS1, but this data is currently inconclusive. Here, we demonstrate, in culture, that a diseased microenvironment can stimulate functional changes of healthy fibroblasts. Future research is still necessary to further dissect the interactions between the ECM and fibroblasts that will help us better understand how the esophagus maintains persistent remodeling.