Zonulin Levels Linked with Increased Intestinal Permeability for IBS

Serum zonulin was found to be upregulated in patients with irritable bowel syndrome (IBS) with levels comparable to those seen in celiac disease, according to the results of a recent study.

If further validated, serum zonulin could serve as a biomarker for altered increasedintestinal permeability in IBS.

“Further studies are needed to confirm our findings and investigate the role of zonulin in IBS,” Prashant Singh, of Beth Israel Deaconess Medical Center, Boston, and colleagues wrote in United European Gastroenterology Journal. “Identifying IBS patients with zonulin-mediated intestinal tight junction dysfunction could enable mechanistically targeted treatment in IBS.”

The study measured serum zonulin and intestinal fatty acid binding protein levels in 50 patients with diarrhea-predominant IBS and 50 patients with constipation-predominant IBS and compared them with levels in 42 healthy controls and 53 patients with celiac disease.

IBS symptom severity was measured with the IBS symptom severity scale.

Median zonulin levels were lowest in the healthy controls (45.2 ng/mL) and highest among patients with celiac disease (66.7 ng/mL). However, patients with constipation-predominant (P=.006) and diarrhea-predominant (P=.009) IBS also had significantly higher zonulin levels compared with healthy controls.

IBS symptom severity scores did not correlate with zonulin in patients in either IBS group. However, in patients with diarrhea-predominant IBS, self-reported dissatisfaction with bowel habits was positively correlated with serum zonulin levels (P=.007).

Patients with diarrhea-predominant and constipation-predominant IBS both had lower intestinal fatty acid binding protein levels compared with patients with celiac disease (P=.005 and P=.007, respectively).

The researchers pointed out several limitations of the study including data of extra-intestinal symptoms such as depression and anxiety, a lack of correlation of the biomarkers with other measures of intestinal permeability, and a lack of data on gluten sensitivity or gut microbiome composition.

Singh P, Silvester J, Chen X, et al. United European Gastroenterol J. 2019;doi:10.1177/2050640619826419.