Plasma cell free DNA characteristics and pro-inflammatory cytokines expression in peripheral blood lymphocytes of patients with autism spectrum disorder - 11th International Symposium on Circulating Nucleic Acids in Plasma and Serum (CNAPS)

Yulia Chudakova ¹ Galina Shmarina ^1,4 Elizaveta Ershova ^1,4 Natalia Veiko ¹ Natalia Sharonova ² Lev Porokhovnik ¹ Natalia Simashkova ³ Svetlana Nikitina ³ Andrey Martynov ¹ Svetlana Kostyuk ^1,4

¹Laboratory of Molecular Biology, Research Centre for Medical Genetics (RCMG), Moscow, Russia
²Biomedical Faculty, Pirogov Russian National Research Medical University (RNRMU), Moscow, Russia
³Department №7, Scientific Center for Mental Health, Russian Academy of Medical Sciences, Moscow, Russia
⁴Laboratory of Student Health and Quality of Life, I.M. Sechenov First Moscow State Medical University (Sechenov University), Moscow, Russia

Cell-free (cf)DNA with elevated levels of oxidative modifications may be one of the factors supporting chronic inflammation in patients with autism spectrum disorder (ASD). This study’s aim was to compare cfDNA concentrations, the levels of oxidative cfDNA modifications in blood plasma as well as the transcript levels for pro-inflammatory cytokines in peripheral blood lymphocytes (PBL) of ASD patients and unaffected controls.

The study included 112 ASD patients (4-10 years old; 80 boys) and 65 healthy controls. cfDNA was isolated from plasma using phenol extraction and quantified by Hoechst 33528 fluorescence. Oxidative modifications of plasma cfDNA samples were assessed by the content of 8-oxo-7,8-dihydro-2’-deoxyguanosine (8-oxodG). The transcript levels for pro-inflammatory cytokines in PBL were evaluated using real-time PCR.

In the group of patients with ASD the median concentration of cfDNA was 3 times higher than that in the healthy controls (p <0.001). The assay of 8-oxodG content in cfDNA samples revealed a significant elevation of this index in patient group. For patients with ASD (but not for healthy controls), a significant negative correlation between cfDNA concentration and 8-oxodG content has been found (R (Spearmen) = -0.569; p<0.002). Analysis of mRNA expression profiles of the genes for pro-inflammatory cytokines in PBL showed that the transcript levels for IL-1b, IL-8 and TNFa in patients with ASD were 3-6 fold higher than those in the healthy controls (all р<0.01).

In conclusion, elevated cfDNA concentrations, increased 8-oxodG content in plasma cfDNA samples as well as increased transcript levels for pro-inflammatory cytokines in PBL suggest the presence of steady-state oxidative stress and systemic aberrant inflammation in ASD patients.

The study was supported by RFBR grant № 17-04-01587 А.