How good is the neosquamous epithelium?

Area of Science:

• Gastroenterology
• Esophageal disease research
• Tissue engineering and regeneration

Background:

• Endoscopic radiofrequency ablation (RFA) with PPI therapy is standard for dysplastic Barrett's esophagus (BE).
• Successful RFA relies on healing with normal-appearing neosquamous epithelium (NSE).
• BE recurrence after RFA raises questions about NSE integrity.

Purpose of the Study:

• To investigate the health and barrier function of NSE post-RFA.
• To compare NSE to normal upper squamous epithelium (USE) in patients undergoing RFA.

Main Methods:

• In vitro analysis of endoscopic biopsies from patients post-RFA on PPIs.
• Morphological assessment (light microscopy) of NSE vs. USE.
• Barrier function evaluation using electrical resistance and fluorescein flux in mini-Ussing chambers.

Main Results:

• NSE displayed dilated intercellular spaces and inflammation compared to USE.
• NSE exhibited significantly defective barrier function (low resistance, high flux).
• Claudin-4, crucial for tight junctions, was downregulated in NSE.

Conclusions:

• NSE possesses a defective barrier function, partly due to claudin-4 downregulation.
• Reduced claudin-4 increases NSE permeability to ions like hydrogen.
• This heightened vulnerability to acid reflux may contribute to BE recurrence after ablation.