Gut Pathogens and Cytokine Profiles in Autism: A Multi-Biosample Analysis

To explore immune, microbial, and gene expression alterations in children with autism spectrum disorder (ASD), assessing their potential as diagnostic markers. Thirty participants, 20 with ASD (15 male, 5 female) and 10 healthy controls, underwent collection of saliva, blood, and stool. Serum cytokines (IL-1β, IL-6, IL-17A, TNF-α) were quantified via ELISA. RT-qPCR assessed corresponding gene expression in blood and saliva. Stool cultures yielded bacterial isolates identified by 16S rRNA sequencing methods. Diagnostic accuracy of cytokines was evaluated using ROC curves. Familial history revealed Down syndrome in 25% of ASD families. Stool cultures produced 31 isolates, predominantly Escherichia (23 E. coli, 5 E. fergusonii, including enterohemorrhagic strains). ASD patients exhibited significantly higher serum cytokine levels (mean ± SE, pg/mL): IL-1β 2275.9 versus 429.3; IL-6109.9 versus 47.6; IL-17A 1457.7 versus 963.6; TNF-α 367.2 versus 148.8 (p < 0.01). Cytokines were strongly intercorrelated, and ROC analysis showed excellent diagnostic potential. Gene expression mirrored serum findings, while salivary cytokine expression varied. Cytokine expression correlated closely with serum protein levels. ASD in this Iraqi cohort is characterized by strong pro-inflammatory signatures and microbial dysbiosis, with IL-6 and TNF-α emerging as potential biomarkers. These markers warrant further investigation for early diagnosis and targeted interventions.