Peripheral Blood Treg/Th17 Imbalance and Altered Th2 Cytokine Profiles in Children with Autism Spectrum Disorder.

BACKGROUND

Intestinal microbial imbalance may cause immune abnormalities, contributing to autism spectrum disorder (ASD). This study investigated immune-related cytokines and T cell subpopulations in children with ASD.

METHODS

In this retrospective cross-sectional study, forty-five children with ASD and 45 age- and sex-matched healthy controls were enrolled. Serum cytokines [interleukin (IL)-10, IL-4, and IL-5] and peripheral blood T cell subpopulations [regulatory T cells (Treg) and T helper type 17 (Th17) cells] were analyzed and compared between groups.

RESULTS

The ASD group exhibited significantly higher Th17 cell proportions (0.41 ± 0.15% vs 0.24 ± 0.13%, P < 0.001), lower Treg cell proportions (5.72 ± 1.92% vs 9.82 ± 0.95%, P < 0.001), and a lower Treg/Th17 ratio (18.33 ± 11.57 vs 50.68 ± 14.12, P < 0.001). Serum IL-10, IL-4, and IL-5 levels were also elevated (IL-10: 59.57 ± 22.41 vs 46.71 ± 15.32 ng/L, P = 0.002). IL-10 levels positively correlated with Th17 cell proportions (r = 0.42, P = 0.004), suggesting a compensatory feedback response. All measurements were performed in peripheral blood.

CONCLUSIONS

Children with ASD exhibited a significant Treg/Th17 imbalance skewed toward Th17 predominance, accompanied by elevated IL-10, IL-4, and IL-5, likely reflecting compensatory anti-inflammatory and Th2 responses. These immune markers may serve as potential biomarkers for ASD, although peripheral blood may not fully reflect gut immune status.