Increased levels of circulating cell-free DNA in COVID-19 patients with respiratory failure.

Cell-free DNA (cfDNA) is released from injured cells and aggravates inflammation. Patients with coronavirus disease (COVID-19) often develop pneumonia and respiratory failure, and require oxygen therapy (OT), including mechanical ventilation (MV). It remains unclear whether cfDNA predicts the risk of receiving OT or MV in COVID-19 patients. Therefore, we hypothesized that circulating cfDNA levels could reflect the severity of respiratory failure and determine a therapeutic approach for oxygenation in patients with COVID-19. We analyzed cfDNA levels in serum samples from 95 hospitalized patients with COVID-19 at Showa University Hospital (Tokyo, Japan). cfDNA levels were assessed by measuring the copy numbers of mitochondrial DNA (mtDNA) and nuclear DNA (nDNA) using quantitative real-time PCR (qPCR). Both cf-nDNA and cf-mtDNA levels were negatively correlated with adjusted SpO2 for FiO2 (SpO2/FiO2 ratio). Elevated cf-nDNA and cf-mtDNA levels were associated with the requirement for OT or MV during patient admission. Multivariate logistic regression analysis revealed that cf-nDNA and cf-mtDNA levels were independent risk factors for OT and MV. These results suggest that both serum cf-nDNA and cf-mtDNA could serve as useful early biomarkers to indicate the necessity of OT or MV in patients with COVID-19.

Tanaka A ，Wakayama K ，Fukuda Y ，Ohta S ，Homma T ，Ando K ，Nishihara Y ，Nakano R ，Zhao J ，Suzuki Y ，Kyotani Y ，Yano H ，Kasahara K ，Chung KP ，Sagara H ，Yoshizumi M ，Nakahira K ... -  《Scientific Reports》

Urinary cell-free mitochondrial and nuclear deoxyribonucleic acid correlates with the prognosis of chronic kidney diseases.

Chang CC ，Chiu PF ，Wu CL ，Kuo CL ，Huang CS ，Liu CS ，Huang CH ... -  《BMC Nephrology》

Comparison of paired cerebrospinal fluid and serum cell-free mitochondrial and nuclear DNA with copy number and fragment length.

Most studies on cell-free DNA (cfDNA) were only for single body fluids; however, the differences in cfDNA distribution between two body fluids are rarely reported. Hence, in this work, we compared the differences in cfDNA distribution between cerebrospinal fluid (CSF) and serum of patients with brain-related diseases. The fragment length of cfDNA was determined by using Agilent 2100 Bioanalyzer. The copy numbers of cell-free mitochondrial DNA (cf-mtDNA) and cell-free nuclear DNA (cf-nDNA) were determined by using real-time quantitative PCR (qPCR) and droplet digital PCR (ddPCR) with three pairs of mitochondrial ND1 and nuclear GAPDH primers, respectively. There were short (~60 bp), medium (~167 bp), and long (>250 bp) cfDNA fragment length distributions totally obtained from CSF and serum using Agilent 2100 Bioanalyzer. The results of both qPCR and ddPCR confirmed the existence of these three cfDNA fragment ranges in CSF and serum. According to qPCR, the copy numbers of long cf-mtDNA, medium, and long cf-nDNA in CSF were significantly higher than in paired serum. In CSF, only long cf-mtDNA's copy numbers were higher than long cf-nDNA. But in serum, the copy numbers of medium and long cf-mtDNA were higher than the corresponding cf-nDNA. The cf-nDNA and cf-mtDNA with different fragment lengths differentially distributed in the CSF and serum of patients with brain disorders, which might serve as a biomarker of human brain diseases.

Chen A ，Li J ，Wang L ，Huang Q ，Zhu J ，Wen S ，Lyu J ，Wu W ... -  《-》

Elevated Cell-Free Mitochondrial DNA in Filtered Plasma Is Associated With HIV Infection and Inflammation.

Arshad O ，Gadawska I ，Sattha B ，Côté HCF ，Hsieh AYY ，Canadian Institutes of Health Research Team on Cellular Aging and HIV Comorbidities in Women and Children (CARMA) ... -  《-》

Increased Circulating Cell-Free DNA in Eosinophilic Granulomatosis With Polyangiitis: Implications for Eosinophil Extracellular Traps and Immunothrombosis.

Endogenous DNA derived from nuclei or mitochondria is released into the blood circulation as cell-free DNA (cfDNA) following cell damage or death. cfDNA is associated with various pathological conditions; however, its clinical significance in antineutrophil cytoplasmic antibody-associated vasculitis (AAV) remains unclear. This study aimed to evaluate the clinical significance of cfDNA in AAV. We enrolled 35 patients with AAV, including 10 with eosinophilic granulomatosis with polyangiitis (EGPA), 13 with microscopic polyangiitis, and 12 with granulomatosis with polyangiitis. Serum cf-nuclear DNA (cf-nDNA) and cf-mitochondrial DNA (cf-mtDNA) levels were measured by quantitative polymerase chain reaction before and after the initiation of immunosuppressive therapy. Tissue samples from EGPA patients were examined by immunofluorescence and transmission electron microscopy. The structure of eosinophil extracellular traps (EETs) and neutrophil extracellular traps (NETs) and stability against DNase were assessed in vitro. Platelet adhesion of EETs were also assessed. Serum cf-nDNA and cf-mtDNA levels were significantly higher in AAV than in healthy controls, with the highest levels in EGPA; however, serum DNase activities were comparable among all groups. cf-nDNA and cf-mtDNA decreased after treatment and were associated with disease activity only in EGPA. Blood eosinophil count and plasma D-dimer levels were significantly correlated with cf-nDNA in EGPA and cf-mtDNA. EGPA tissue samples showed lytic eosinophils and EETs in small-vessel thrombi. The structure of EETs showed bolder net-like chromatin threads in vitro and EETs showed greater stability against DNase than NETs. EETs provided a scaffold for platelet adhesion. cfDNA was increased in EGPA, associated with disease activity. The presence of DNase-resistant EETs in small-vessel thrombi might contribute to higher concentration of cfDNA and the occurrence of immunothrombosis in EGPA.

Hashimoto T ，Ueki S ，Kamide Y ，Miyabe Y ，Fukuchi M ，Yokoyama Y ，Furukawa T ，Azuma N ，Oka N ，Takeuchi H ，Kanno K ，Ishida-Yamamoto A ，Taniguchi M ，Hashiramoto A ，Matsui K ... -  《Frontiers in Immunology》