Background
Eosinophilic esophagitis is an allergic disease of increasing worldwide incidence. Complications are due to tissue remodeling and involve transforming growth factor-β1 (TGFβ1) mediated fibrosis. Plasminogen Activator Inhibitor-1 (PAI-1/serpinE1) can be induced by TGFβ1 but its role in EoE is not known.
Objective
To understand the expression and role of PAI-1 in EoE.
Methods
We used esophageal biopsy specimens and plasma samples from control and EoE subjects, primary human esophageal epithelial cells, and EoE fibroblasts in immunohistochemistry, quantitative PCR, and immunoassay experiments to understand the induction of PAI-1 by TGFβ1, the relationship between PAI-1 and esophageal fibrosis, and the role of PAI-1 in fibrotic gene expression.
Results
PAI-1 expression was significantly elevated in epithelial cells of active EoE biopsies as compared with inactive EoE or control biopsies (p<0.001). Treatment of primary esophageal epithelial cells with recombinant TGFβ1 increased PAI-1 transcription, intracellular protein expression, and secretion. Esophageal PAI-1 expression correlated with basal zone hyperplasia, a fibrosis, and markers of esophageal remodeling including vimentin, TGFβ1, collagen I, fibronectin, and matrix metalloproteases and plasma PAI-1 levels correlated with plasma TGFβ1. PAI-1 inhibition significantly decreased baseline and TGFβ1-induced fibrotic gene expression.
Conclusions
PAI-1 is significantly elevated in the EoE epithelium, reflects fibrosis, and its inhibition decreases TGFβ1-induced gene expression. Epithelial PAI-1 may serve as a marker of EoE severity and form part of a TGFβ1-induced pro-fibrotic network.
Background:
Eosinophilic esophagitis (EoE) is a chronic Th2-assocated inflammatory condition accompanied by substantial impairments in epithelial barrier function and increased numbers of interleukin 9 (IL-9) expressing inflammatory cells. While IL-9 is known to affect barrier function in the intestine, the functional effects of IL-9 on the esophagus are unclear. Herein we aimed to understand the expression of the IL-9 receptor and effects of IL-9 on the epithelium in EoE.
Methods:
We used esophageal biopsies from pediatric EoE patients with active and inactive disease to analyze the expression of the IL-9 receptor, the adherens junction protein E-cadherin and the tight junction protein claudin-1. We treated primary human esophageal epithelial cells with IL-9 to understand its effects on E-cadherin expression and function.
Results:
Active EoE subjects had increased epithelial expression of IL-9 receptor mRNA and protein (P < 0.05) and decreased membrane bound E-cadherin (P < 0.01) and claudin-1 (P < 0.05) expression. IL-9 receptor expression and mislocalized claudin-1 positively correlated and while membrane bound E-cadherin expression negatively correlated with the degree of histologic epithelial remodeling (P < 0.05). IL-9 decreased epithelial resistance in stratified primary human esophageal epithelial cells (P < 0.01) and membrane bound E-cadherin in epithelial cell monolayers (P < 0.01).
Conclusions:
These data suggest that IL-9, its receptor, and its effects on E-cadherin may be important mechanisms for epithelial barrier disruption in EoE.
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