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

Abstract

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-1 beta, IL-1 alpha, IL-4, IL-6, IL-17, TNF-alpha and TGF-beta 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-1 alpha 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.