Introduction
Stretta, a minimally invasive endoscopic procedure, has demonstrated efficacy in improving GERD symptoms by delivering radiofrequency energy to the lower esophageal sphincter. Despite its effectiveness, there is limited understanding of Stretta's impact on the epithelial barrier function.
Aims & Methods
This study aims to investigate changes in epithelial barrier function in GERD patients who underwent Stretta treatment. Tight junction gene expression levels, measurement of dilated intercellular spaces (DIS), and electrophysiological and permeability properties of the esophageal epithelium were investigated in order to determine the epithelial barrier function characteristics of patients treated with Stretta.
Six Stretta-treated (3 men, 38.5±4.9 years) patients and 15 (7 men, 36.2±6.3 years) healthy volunteers (HV) were included in the study. Esophageal epithelial biopsies taken during endoscopy were used as study material. In order to determine tight junction gene expressions, qRT-PCR method was used for the expression levels of 6 (E- cadherin, Zonula ocludens 1, Zonula ocludens 2, Claudin 1, Claudin 4, Occludin) genes. Ussing chamber system was used to determine the transepithelial resistance (TEER) of the esophageal epithelium and permeability properties were examined by a fluorometric method. In DIS measurements, For each patient, photographs were taken from 10 different areas without artifacts under the light microscope at 1000x magnification. Ten vertical measurements were made continuously around the single epithelial cell with the largest DIS between the upper part of the Stratum Basale and the six parts of the Stratum Spinosum. A total of 100 blind measurements were made by a single investigator for each patient.
Results
In comparing the gene expressions of tight junctions before (Pre-str) and after Stretta (Post-str), it was observed that only the expression of the Claudin 4 gene was 6.91 (p=0.02) fold higher in the Post-str group compared to the Pre-str group. Similarly compared to the HV group, the Post-str group exhibited a 6.02-fold (p=0.001) increase in Claudin 4 expression.
Comparing the TEER results between the pre-str (110.8 Ω) and post-str (151.7 Ω) groups, although there is a numerical increase, no statistically significant difference was observed. In addition, the TEER values of the HV (165,8 Ω ) group were statistically significantly higher than the Pre-str group. Upon examining the permeability results, it was determined that the Post-str (30.1 pmol) group had lower permeability compared to the Pre-str (67.3 pmol) group (p=0.043), while there was no statistically difference observed between the HV (34.4 pmol) group and the Stretta groups.
According to the study findings, the group that exhibited the largest DIS was the Post-str (0.974±0.212) group. However, no statistically significant difference was observed between the Pre-str (1.030±0.266) and Post-str groups in terms of DIS. Notably, a significant difference (p=0.03) was only observed between the HV (1.374±0.269) group and the Post-str group.
Conclusion
In summary, our findings suggest that treatment with Stretta strengthens the epithelial barrier function, as evidenced by the increase in Claudin 4 expression and the corresponding decrease in fluorescent permeability. However, the lack of support from our DIS results in terms of gene expression and electrophysiological changes suggests the need for further investigation to fully understand the effects of Stretta treatment on the epithelial barrier.
