Cytokine expression profiles in Autism spectrum disorder: A multi-center study from Turkey

Autism Spectrum Disorder (ASD) is a complex neurodevelopmental disorder characterized by impairments in communication and social interaction as well as restricted interests and repetitive behaviors. The pathogenesis of ASD is not completely understood, but a growing body of research has demonstrated that the immune response may be a contributing factor in the etiology and/ or ontogeny of ASD. The aim of this study was to determine the expression levels of IL-1β, IL-1α, IL-4, IL-6, IL-17, TNF-α and TGF-β in peripheral blood mononuclear cells of children with ASD and healthy controls in order to determine the contributions of cytokines to ASD. Within the study timeframe, 195 children with ASDs (80.5% male) and 162 controls (73.6% male) were enrolled. Most children with ASD had a comorbid disorder (n = 114, 58.5%), with the most common diagnoses as Intellectual Developmental Disorder (IDD, n = 64, 32.8%) and ADHD (n = 64, 32.8%). The majority of children with ASD had severe autistic symptoms as evaluated via Childhood Autism Rating Scale (CARS, n = 130, 64.6%). The mean CARS score in the ASD sample was 40.8 (S.D. = 7.6). The patients with ASD were found to have significantly higher levels of IL-6 (p < 0.001) and significantly lower levels of IL-17 (p < 0.05, all Bonferroni corrected). Treatment tended to affect IL-4 levels. Lastly, discriminant function analysis (DFA) revealed that a combination of IL-6, IL-17 and IL-1α correctly classified 56.6% of cases. Despite extensive immunological evidence suggesting immune system aberrations, further research is required to clarify the relationship between immune profiles and ASD symptoms.