Serum Zonulin and Claudin-5 but not Interferon-Gamma and Interleukin-17A Levels Increased in Children with Specific Learning Disorder: A Case-Control Study.

Background: Gut-blood and blood-brain barrier permeabilty (gut-brain axis) has been attracting increased attention in the etiology of neurodevelopmental disorders. In this study, we aimed to investigate serum levels of zonulin (a biomarker of intestinal permeability), claudin-5 (a biomarker of blood-brain barrier permeability), and interferon-gamma and interleukin-17A in children with specific learning disorder.

Methods: Forty-three children with DSM-5 diagnosis of specific learning disorder and 43 healthy children were included in this study. Serum levels of zonulin, claudin-5, interferon-gamma, and interleukin-17A were measured using commercial enzyme-linked immunosorbent assay kits.

Results: Serum zonulin and claudin-5 levels of the study group were significantly higher than the control group according to the multivariate analysis of covariance test while controlling for age, gender, and body mass index. However, serum interferon-gamma and interleukin-17A levels were not significantly different between the two groups. There was no correlation either between zonulin and interferon-gamma and interleukin-17A or claudin-5 and interferon-gamma and interleukin-17A.

Conclusion: Gut-blood and blood-brain barrier permeability may be disrupted in subjects with special learning disorder. Further research is needed to determine whether zonulin and claudin-5 may be biomarkers, and some dietary interventions or specific agents such as zonulin or claudin-5 inhibitors could be used in the management of neurodevelopmental disorders including special learning disorder.