Cell-free DNA release following psychosocial and physical stress in women and men

Abstract

Cell-free DNA (cfDNA) is continuously shed by all cells in the body, but the regulation of this process and its physiological functions are still largely unknown. Previous studies have shown that nuclear (cf-nDNA) and mitochondrial (cf-mtDNA) cfDNA increase in plasma in response to acute psychosocial and physical stress in men. These findings have now been further investigated by testing female participants for the first time and comparing the results with those of men. In addition, cf-nDNA and cf-mtDNA was comparatively quantified in both plasma and saliva at all measurement times. To obtain plasma, a novel method was implemented that allows, easy sampling of arterial blood by non-medical professionals. Although cf-mtDNA can be easily detected in body fluids due to its high copy number, cf-nDNA is more difficult to quantify because of its low copy number. To address this issue, a multiplex quantitative polymerase chain reaction (qPCR) protocol was utilized to detect LINE elements, which are abundant in the human genome. The analysis revealed significantly increased levels of cf-nDNA in plasma and saliva in all female and male participants after psychosocial and physical stress. However, neither plasma nor saliva showed a consistent or stress-induced release pattern for cf-mtDNA. CfDNA is a promising biomarker that is released after stress in both men and women and can be reliably detected in plasma and saliva. The mechanisms by which cfDNA is released from specific cells and its biological function in the body need to be elucidated in future research.