# Diagnostic study of serum claudin-3 and zonulin for intestinal barrier dysfunction after abdominal surgery

## TL;DR

This study investigates how serum claudin-3 and zonulin can help diagnose intestinal barrier dysfunction after abdominal surgery.

## Contribution

The study demonstrates that serum claudin-3 is a more accurate diagnostic marker than zonulin for postoperative intestinal barrier dysfunction.

## Key findings

- Serum claudin-3 and zonulin concentrations peak at 24 hours post-reperfusion and correlate with intestinal mucosal injury.
- Serum claudin-3 has a higher diagnostic accuracy (AUC=0.934) than zonulin (AUC=0.826) for intestinal barrier dysfunction.
- E. coli copy number increases in patients with intestinal barrier dysfunction 24 hours post-surgery.

## Abstract

Previous studies have shown that serum claudin-3 and zonulin play important roles in reflecting intestinal barrier function. This study aims to explore the diagnostic value of serum claudin-3 and zonulin in assessing intestinal barrier dysfunction following abdominal surgery.

A rat model of intestinal ischemia–reperfusion (I/R) injury was established, and hematoxylin and eosin (HE) staining was performed to observe the damage to the intestinal mucosa. Pearson correlation analysis was conducted to assess the relationship between changes in serum claudin-3 and zonulin concentrations and the degree of intestinal mucosal injury. Subsequently, patients undergoing abdominal surgery were included in the clinical study to measure the levels of claudin-3 and zonulin in the blood; peripheral blood Escherichia coli 16sDNA was detected using qPCR technology. The diagnostic value of serum claudin-3 and zonulin in relation to intestinal barrier dysfunction was analyzed using ROC curves.

The degree of intestinal mucosal injury in rats and the concentrations of serum claudin-3 and zonulin both exhibited a trend of initially worsening and then improving, peaking at 24 h post-reperfusion. The changes in serum claudin-3 and zonulin concentrations were significantly positively correlated with the degree of intestinal mucosal tissue injury. In patients with intestinal barrier dysfunction, the copy number of Escherichia coli and the concentrations of serum claudin-3 and zonulin significantly increased at 24 h post-operation; the area under the ROC curve for serum claudin-3 and zonulin were AUC = 0.934 and AUC = 0.826, respectively.

Following intestinal mucosal injury, the greater the degree of damage, the higher the concentrations of serum claudin-3 and zonulin, which are positively correlated, peaking at 24 h post-operation. Serum claudin-3 and zonulin have good predictive value for postoperative intestinal barrier dysfunction, with serum claudin-3 demonstrating a higher diagnostic value than serum zonulin for postoperative intestinal barrier dysfunction.