Circulating extracellular DNA (ecDNA) is known to worsen the outcome of many diseases. ecDNA released from neutrophils during infection or inflammation is present in the form of neutrophil extracellular traps (NETs). It has been shown that higher ecDNA concentration occurs in a number of inflammatory diseases including inflammatory bowel disease (IBD). Enzymes such as peptidyl arginine deiminases (PADs) are crucial for NET formation. We sought to describe the dynamics of ecDNA concentrations and fragmentation, along with NETosis during a mouse model of chemically induced colitis. Plasma ecDNA concentration was highest on day seven of dextran sulfate sodium (DSS) intake and the increase was time-dependent. This increase correlated with the percentage of cells undergoing NETosis and other markers of disease activity. Relative proportion of nuclear ecDNA increased towards more severe colitis; however, absolute amount decreased. In colon explant medium, the highest concentration of ecDNA was on day three of DSS consumption. Early administration of PAD4 inhibitors did not alleviate disease activity, but lowered the ecDNA concentration. These results uncover the biological characteristics of ecDNA in IBD and support the role of ecDNA in intestinal inflammation. The therapeutic intervention aimed at NETs and/or nuclear ecDNA has yet to be fully investigated.

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CD39 is an ectonucleotidase that initiates conversion of extracellular nucleotides into immunosuppressive adenosine. CD39 is expressed by regulatory T (Treg)-cells, where it mediates immunosuppression, and by a subset of T-helper (Th) 17-cells, where it limits pathogenicity. CD39 is regulated via single-nucleotide-polymorphisms and upon activation of aryl-hydrocarbon-receptor and oxygen-mediated pathways. Here we report a mechanism of CD39 regulation that relies on the presence of an endogenous antisense RNA, transcribed from the 3′-end of the human CD39/ENTPD1 gene. CD39-specific antisense is increased in Treg and Th17-cells of Crohn’s disease patients over controls. It largely localizes in the cell nucleus and regulates CD39 by interacting with nucleolin and heterogeneous-nuclear-ribonucleoprotein-A1. Antisense silencing results in CD39 upregulation in vitro and amelioration of disease activity in a trinitro-benzene-sulfonic-acid model of colitis in humanized NOD/scid/gamma mice. Inhibition/blockade of antisense might represent a therapeutic strategy to restore CD39 along with immunohomeostasis in Crohn’s disease.