Detergent exposure induces epithelial barrier dysfunction and eosinophilic inflammation in the esophagus

Abstract

Background: Eosinophilic esophagitis (EoE) is a chronic allergic disease associated with type 2 inflammation and epithelial barrier dysfunction. The etiology is unknown, however, genetic heritability studies suggest environmental factors play a key role in pathogenesis. Detergents, such as sodium dodecyl sulfate (SDS), are common ingredients in household products such as dish soap and toothpaste. We hypothesized detergent exposure decreases epithelial barrier function and induces esophageal inflammation.

Methods: Immortalized esophageal epithelial cells (EPC2) were cultured in air-liquid interface (ALI) and exposed to SDS. Barrier function/activity was assessed by transepithelial electrical resistance (TEER), FITC-dextran flux, and RT-PCR. Additionally, SDS-treated mouse esophageal organoids were evaluated for morphology. To investigate the effects of SDS in vivo, mice were treated with 0.5% SDS in drinking water for 14 days. Esophagi were assessed by gross morphology, histopathology, protein expression, and bulk RNA sequencing.

Results: When EPC2 cells were exposed to SDS (5 μg/ml) for 96 h, TEER decreased (p = 0.03), and FITC-dextran flux increased (p = 0.0002). mRNA expression of IL-33 increased 4.5-fold (p = 0.02) at 6 h and DSG1 decreased (p < 0.0001) by 72 h. Disrupted epithelial integrity was noted in SDS-treated esophageal organoids. When mice were exposed to SDS, they showed increased esophageal width, chemokine, and metalloprotease levels. Mice treated with SDS also showed increased IL-33 protein expression, basal zone hyperplasia, CD4⁺ cell infiltration, and esophageal eosinophilia. RNA sequencing revealed upregulation of immune response pathway genes.

Conclusion: Exposure to SDS decreases esophageal barrier integrity, stimulates IL-33 production, and promotes epithelial hyperplasia and tissue eosinophilia. Detergents may be a key environmental trigger in EoE pathogenesis.

Keywords: IL-33; detergent; eosinophilic esophagitis; epithelium.

Figure 1.. SDS induces epithelial barrier dysfunction in vitro.

(A) Kinetic changes in TEER in EPC2 ALI cultures exposed to serial dilutions of SDS are shown. Data are presented as mean±SEM of 3 samples and are a representative of 4 experiments. *p < 0.05 compared to the cells with no SDS. (B) EPC2 ALI cultures were exposed to SDS for 96 hrs and permeability to FITC-dextran was examined. Data are presented as mean±SEM of 4 samples. ***p < 0.0001 between the groups indicated by a horizotal line. (C) EPC2 cells were exposed to SDS for 6 hrs (for IL-33) or 72 hrs (for DSG1), and the expression of mRNA for IL-33 and DSG1 was examined by real-time RT-PCR. Data are presented as mean±SEM of 3-4 samples. *p < 0.05, **p < 0.01, ****p < 0.0001 between the groups indicated by horizontal lines.

Figure 2.. SDS alters epithelium in esophageal organoids.

Esophageal organoid cultures were generated ex vivo from naïve wild-type mice. Organoids (n ≥ 10) were exposed to SDS (200 ng/mL) during culture (days 5-9) or untreated and collected on culture day 11 for histology. Representative organoids shown with phase contrast, H&E staining. Scale bar = 50um.

Figure 3.. SDS induces eosinophilic inflammation, CD4 lymphocyte infiltration, BZH, and IL-33 expression.

Esophagus was collected from mice exposed to 0.5% SDS in drinking water and compared with regular drinking water controls. Cross-sections were stained with H&E, EPX, CD4, Ki-67, and IL-33. Insets are included for detail for SDS-treated mice. Serial sections are shown from representative mice (n=5 treatment, 5 controls). Scale bars = 200 μm. Inset scale bars = 100 μm.

Figure 4.. SDS alters gene expression in the mouse esophagus.

RNA-Seq of whole esophagus homogenates from mice treated with 0.5% SDS in drinking water for 14 days vs. regular drinking water. (A) Heatmap of immune response gene expression. (B) Volcano plot of differentially expressed genes showed changes in barrier- (epithelial) and inflammation-associated (eosinophil, T cell) genes (highlighted yellow). (C) Pathway analysis showing upregulated and downregulated gene expression associated with inflammatory and remodeling pathways. (n=3-5 mice).