Evaluation of blood zonulin levels, inflammatory processes and neuronal changes in children with autism spectrum disorder

Aim: Autism Spectrum Disorder (ASD) is a neurodevelopmental disorder with impaired social communication and interaction. Although the cause is not yet known, it has been suggested that genetic and environmental factors play a role in its etiology. In recent years, it has been emphasized that the immune-inflammatory system, one of the environmental factors, may also play a role in this disease. In this study, it was aimed to evaluate intestinal permeability, antibody levels against food antigens and bacterial wall, inflammatory processes and changes in neuron damage in patients diagnosed with ASD and to compare them with the control group. Method: 35 patients who were diagnosed with ASD according to DSM-5 diagnostic criteria and 35 healthy children between the ages of 3-12 were included in the study. The height and weight of all the participants were measured and Childhood Autism Rating Scale (CARS) was applied to the study group. In addition, the Sociodemographic Data Form (SDF) and the Development Assessment Form (DAF) were filled with the parents. Venous blood samples were taken from ASD and control groups, serum zonulin, anti-gliadin IgA-IgG, anti-LPS IgG, IL6, TNF-alpha, TGF-B, S100B and NSE levels were measured by enzyme-like immuno-sorbent test (ELISA). Results: Serum zonulin levels were significantly lower in the ASD group. IL-6 and TGF-β levels among inflammatory factors were significantly higher in the study group. No statistically significant difference was observed between the two groups in terms of serum Antigliadin Ig-A, Antigliadin Ig-G, Anti-LPS Ig-G and TNF-α values. Again, NSE and S100B levels were similar between ASD and control groups. A positive correlation was observed between the 14th subscale of CARS, evaluating the intellectual level, and the values of Anti-LPS, IL-6, TGF-Beta, S100B. In addition, a positive relationship was found between zonulin and IL-6, Anti-LPS, TNF-alpha, TGF-Beta, NSE, S100B. Conclusion: In this study, zonulin levels, which is an indicator of intestinal permeability in ASB, were found to be lower than controls. However, antibody levels against food antigens or bacterial wall were similar to the control group. In addition, although it has been shown that the inflammatory process increases in ASD, no change in neuronal damage indicators was detected. These results indicate that zonulin levels may be low in patients with autism, especially when comorbid GIS disorders are excluded, and this may be associated with inflammatory processes. However, larger sample size follow-up studies are needed to support these findings. Keywords: Autism; zonulin; inflammation; neuronal damage