ENaCδ aggravates gastroesophageal reflux disease via PI3K/AKT/mTOR: Human umbilical cord mesenchymal stem cells restore barrier function

Abstract

BACKGROUND

Gastroesophageal reflux disease (GERD) is a widely occurring digestive disorder associated with persistent esophageal inflammation and compromised epithelial barrier integrity. Increasing evidence suggests that ion channels, particularly the epithelial sodium channel (ENaC), play a role in mucosal homeostasis and inflammatory regulation. The δ subunit of ENaC (ENaCδ), which is expressed in human tissues but absent in conventional rodent models, may contribute to disease pathogenesis. However, its role in GERD remains unclear, and current treatments such as proton pump inhibitors are often insufficient in addressing inflammation and barrier dysfunction. Human umbilical cord mesenchymal stem cells (hUC-MSCs) have emerged as a promising therapeutic strategy due to their anti-inflammatory and tissue-repair properties.

AIM

To investigate the role of human ENaCδ in the development and progression of GERD using a humanized ENaCδ (hENaCδ) mouse model, and to evaluate the therapeutic potential of hUC-MSCs in alleviating esophageal inflammation and restoring epithelial barrier function.

METHODS

In the present study, a total of 48 mice were randomly assigned to eight experimental groups to investigate the role of hENaCδ in GERD and to evaluate the therapeutic potential of hUC-MSCs. A hENaCδ mouse model was established using CRISPR/Cas9 technology, followed by esophageal acid perfusion to induce GERD.

RESULTS

hENaCδ exacerbated inflammatory infiltration in the submucosa of the esophagus in GERD mice, promoted the expression of interleukin (IL)-1, IL-1β, IL-17 and inducible nitric oxide synthase in mice (P < 0.001), upregulated the relative expression and phosphorylation levels of phosphoinositide 3-kinase (PI3K), protein kinase B (AKT), and mammalian target of rapamycin (mTOR) (P < 0.05), and downregulated the expression of myosin phosphatase target subunit 1 (MYPT1) and claudin-1 (P < 0.001). hUC-MSCs could alleviate the pathological changes of GERD mice with hENaCδ, inhibit the expression of IL-1, IL-1β, IL-17 and inducible nitric oxide synthase in mice (P < 0.001), downregulate the expression of PI3K, AKT and mTOR in esophageal tissue (P < 0.001), and upregulate the expression of MYPT1 and claudin-1 (P < 0.001). Although both hUC-MSCs and proton pump inhibitor treatments could effectively alleviate the inflammatory response of GERD, hUC-MSCs had a more significant effect in inhibiting IL-17 and restoring the expression of MYPT1 and claudin-1.

CONCLUSION

hENaCδ exacerbates GERD-related inflammation and barrier injury in mice by activating the PI3K/AKT/mTOR pathway and downregulating MYPT1 and claudin-1, while hUC-MSCs treatment can effectively block this pathway and reduce inflammation and barrier injury.

Keywords: Human umbilical cord mesenchymal stem cells; Gastroesophageal reflux disease; Humanized epithelial sodium channel δ mouse model; Epithelial sodium channel; Proton pump inhibitor

Core Tip: We developed a CRISPR/Cas9-generated humanized epithelial sodium channel δ mouse model to better mimic human gastroesophageal reflux disease. Humanized epithelial sodium channel δ aggravated acid-induced esophageal inflammation by activating the phosphatidylinositol 3-kinase/protein kinase B/mammalian target of rapamycin pathway, increasing interleukin 1 (IL-1), IL-1β, IL-17 and inducible nitric oxide synthase, and impairing barrier and contractile regulators (claudin-1 and myosin phosphatase target subunit 1). Human umbilical cord mesenchymal stem cells reversed these changes and outperformed proton pump inhibitor in suppressing IL-17 and restoring claudin-1/myosin phosphatase target subunit 1.