Oxidized cell-free DNA as a stress-signaling factor activating the chronic inflammatory process in patients with autism spectrum disorders.

BACKGROUND: Autism spectrum disorders (ASD) are known to be associated with an inflammatory process related to immune system dysfunction. This study's aim was to investigate the role of cell-free DNA in chronic inflammatory process in ASD patients. METHODS: The study included 133 ASD patients and 27 healthy controls. Sixty-two ASD patients were demonstrated to have mild-to-moderate disease severity (group I) and 71 individuals to have severe ASD (group II). Plasma cell-free (cf) DNA characteristics, plasma cytokine concentrations, expression of the genes for NFкB1 transcription factor and pro-inflammatory cytokines TNFα, IL-1ß and IL-8 in peripheral blood lymphocytes (PBL) of ASD patients, and unaffected controls were investigated. Additionally, in vitro experiments with oxidized DNA supplementation to PBL cultures derived from ASD patients and healthy controls were performed. RESULTS: The data indicates that ASD patients have demonstrated increased cfDNA concentration in their circulation. cfDNA of patients with severe ASD has been characterized by a high abundance of oxidative modification. Furthermore, ASD patients of both groups have shown elevated plasma cytokine (IL-1ß, IL-8, IL-17A) levels and heightened expression of genes for NFкB1 nuclear factor and pro-inflammatory cytokines TNFα, IL-1ß, and IL-8 in PBL. In vitro experiments have shown that NF-κB/cytokine mRNA expression profiles of ASD patient PBL treated with oxidized DNA fragments were significantly different from those of healthy controls. CONCLUSIONS: It may be proposed that oxidized cfDNA plays a role of stress-signaling factor activating the chronic inflammatory process in patients with ASD.

Association of NEF2L2 Rs35652124 Polymorphism with Nrf2 Induction and Genotoxic Stress Biomarkers in Autism.

Increased oxidative/genotoxic stress is known to impact the pathophysiology of ASD (autism spectrum disorder). Clinical studies, however, reported limited, heterogeneous but promising responses to treatment with antioxidant remedies. We determined whether the functional polymorphism of the Nrf2 gene, master regulator of anti-oxidant adaptive reactions to genotoxic stress, links to the genotoxic stress responses and to an in vitro effect of a NRF2 inductor in ASD children. Oxidative stress biomarkers, adaptive responses to genotoxic/oxidative stress, levels of master antioxidant regulator Nrf2 and its active form pNrf2 before and after inducing by dimethyl fumarate (DMF), and promotor rs35652124 polymorphism of NFE2L2 gene encoding Nrf2 were studied in children with ASD (n = 179). Controls included healthy adults (n = 101). Adaptive responses to genotoxicity as indicated by H2AX and cytoprotection by NRF2 contents positively correlated in ASD children with a Spearman coefficient of R = 0.479 in T+, but not CC genotypes. ASD children with NRF2 rs35652124 CC genotype demonstrated significantly higher H2AX content (0.652 vs. 0.499 in T+) and pNrf2 induction by DMF, lowered 8-oxo-dG concentration in plasma and higher cfDNA/plasma nuclease activity ratio. Our pilot findings suggest that in ASD children the NEF2L2 rs35652124 polymorphism impacts adaptive responses that may potentially link to ASD severity. Our data warrant further studies to reveal the potential for NEF2L2 genotype-specific and age-dependent repurposing of DMF and/or other NRF2-inducing drugs.