The Biology of CNAPS

Multiple Ways of cfDNA Reception and Following ROS Production in Endothelial Cells

Oxidized cell-free DNA acts as a stress signal molecule and triggers an adaptive response in human cells. Various membrane DNA recognizing receptors are known as potential sensors for such DNA fragments. In order to clarify which of these sensors are able to interact with cfDNA fragments, circulating in human blood flow in heath and disease, we studied the influence of various cfDNA types on endothelial cells. We incubated these fragments at a physiologically optimal concentration with HUVEC cells for 3-24 h and detected the expression of either TLR9 or AIM2, RIG1 and STING receptors at mRNA and protein levels. We estimated that the activation of both TLR9 and other types of intracellular receptors initiates stress signaling in the endothelium independently. Signal transduction through these receptors activates NOX4 as the main source of ROS production in HUVECs.

Human circulating plasma DNA significantly decreases while lymphocyte DNA damage increases under chronic occupational exposure to low-dose gamma-neutron and tritium β-radiation

The blood plasma of healthy people contains cell-fee (circulating) DNA (cfDNA). Apoptotic cells are the main source of the cfDNA. The cfDNA concentration increases in case of the organism's cell death rate increase, for example in case of exposure to high-dose ionizing radiation (IR). The objects of the present research are the blood plasma and blood lymphocytes of people, who contacted occupationally with the sources of external gamma/neutron radiation or internal β-radiation of tritium N = 176). As the controls (references), blood samples of people, who had never been occupationally subjected to the IR sources, were used (N = 109). With respect to the plasma samples of each donor there were defined: the cfDNA concentration (the cfDNA index), DNase1 activity (the DNase1 index) and titre of antibodies to DNA (the Ab DNA index). The general DNA damage in the cells was defined (using the Comet assay, the tail moment (TM) index). A chronic effect of the low-dose ionizing radiation on a human being is accompanied by the enhancement of the DNA damage in lymphocytes along with a considerable cfDNA content reduction, while the DNase1 content and concentration of antibodies to DNA (Ab DNA) increase. All the aforementioned changes were also observed in people, who had not worked with the IR sources for more than a year. The ratio cfDNA/(DNase1×Ab DNA × TM) is proposed to be used as a marker of the chronic exposure of a person to the external low-dose IR. It was formulated the assumption that the joint analysis of the cfDNA, DNase1, Ab DNA and TM values may provide the information about the human organism's cell resistivity to chronic exposure to the low-dose IR and about the development of the adaptive response in the organism that is aimed, firstly, at the effective cfDNA elimination from the blood circulation, and, secondly - at survival of the cells, including the cells with the damaged DNA.