Cell-free DNA in sepsis: from molecular insights to clinical management.

Sepsis is a dysregulated host response to infection that frequently results in fatal multiple organ dysfunction. Despite advances in clinical identification and management, both its incidence and mortality have remained persistently high. Emerging evidence indicates that cell-free DNA (cfDNA), as a novel biomarker and molecular therapeutic target, holds promise for improving the clinical management of sepsis. cfDNA refers to DNA fragments present in body fluids, including naked DNA, membrane-coated DNA, nucleosomes, and neutrophil extracellular traps (NETs). cfDNA is released from host cells or pathogens into body fluids through pathways, such as NETosis, mitochondrial damage, cell necrosis, apoptosis, pyroptosis, and erythroblast enucleation. The released cfDNA triggers a strong inflammatory response by activating Toll-like receptor (TLR) 9, the absent in melanoma 2 (AIM2) inflammasome, and the cyclic GMP-AMP synthase (cGAS)-stimulator of interferon genes (STING) signaling pathway. At the same time, cfDNA activates the coagulation cascade and inhibits anticoagulant and fibrinolytic systems through multiple mechanisms, resulting in microcirculatory disorders. These pathological effects are closely associated with sepsis-related organ dysfunction and poor prognosis. Elucidation of the release and pathological mechanisms of cfDNA provides a foundation for the development of targeted treatment strategies. Currently, molecular therapeutic approaches targeting cfDNA, including peptidylarginine deiminase (PAD) 4 inhibitors, pore-forming inhibitors, antioxidants, cfDNA scavengers, and deoxyribonucleases (DNases), have shown certain efficacy in treating sepsis and systemic inflammation. In terms of sepsis monitoring, compared with traditional markers, cfDNA exhibits extremely high timeliness and dynamic monitoring capability. cfDNA can simultaneously indicate the complex interplay among infection, host response, and organ damage, making it suitable for early diagnosis, prognosis assessment, treatment monitoring, organ function evaluation, and pathogen detection. Given its broad application prospects in the diagnosis and treatment of sepsis, this paper systematically elaborates on the mechanisms of cfDNA release and pathological effects in sepsis, reviews progress in cfDNA-targeted monitoring and therapeutic strategies, discusses technical challenges, and outlines potential future directions.