Elevated nuclear and mitochondrial cell-free deoxyribonucleic acid measurements are associated with death after infant cardiac surgery

Advancing cell-free DNA as a biomarker of damage to heart caused by ionizing radiation

Exposure to diagnostic and therapeutic radiation introduces risks for development of diseases later in life by causing DNA damage in cells. Currently, there is no clinical method for determining exposure risk caused by radiation toxicity to DNA. Cell-free DNA (cfDNA), a marker of DNA damage, is currently used to assess risk for long-term effects following organ transplantation, surgery and inflammation. The goal of our proposed study is to develop cfDNA as an early biomarker for assessing risk for cardiovascular disease and cancer from radiation exposure so that strategies to mitigate the damaging effects of medical radiation can be assessed. Hearts from male and female WAG/RijCmcr rats (n = 6-10/group) were exposed to increasing doses of X-radiation (50 mGy and 3.5 Gy). Blood was collected prior to and after (15 minutes-96 hours) irradiation, and cell-free plasma was prepared. Primers and probes were designed for quantitative analysis of sequences of mitochondria (12S rRNA) and nuclear (Gapdh) cfDNA present in rat plasma using quantitative reverse transcription polymerase chain reaction (RT-qPCR). Exposure of hearts to radiation increased nuclear and mitochondrial cfDNA in a dose-dependent manner. Three point five grays from X-radiation increase cfDNA for Gapdh in plasma after 1 hour with a 15.8-fold increase (P < 0.001) after 6 hours. The earliest time nuclear and mitochondrial cfDNA increases were detected in plasma was at 60 minutes following exposure to 3.5 Gy. cfDNA has potential to advance as a biomarker of exposure to medical doses of radiation in patients.

Cell-free mitochondrial DNA may predict the risk of post-operative complications and outcomes in surgical aortic valve replacement patients

Surgical aortic valve replacement (AVR) is the standard of care for severe aortic valve disease; however, post-operative complications continue to pose challenges. Inflammation caused by increased release of cell-free mitochondrial DNA (cf-mtDNA) during surgery may be a contributing factor. The aim of this pilot study was to investigate the relationship between cf-mtDNA release and the risk of inflammatory-mediated post-operative complications in adult AVR patients. Plasma was collected from patients undergoing an AVR with cardiopulmonary bypass (CPB) at baseline, intra-operatively and post ICU admission at 6, 12 and 18 h. Cf-mtDNA was quantified and inflammatory biomarker expression in leukocytes and plasma was assessed. Cf-mtDNA levels increased 16-fold at the end of CPB with a corresponding increase in average fragment size. Cf-mtDNA levels may be associated with post-operative bleeding, infection, hepatic failure and hospital length of stay. Gene expression and plasma analysis revealed altered levels of markers associated with inflammation and innate immune responses. Several markers were associated with post-operative complications and outcomes. Our results indicate that cf-mtDNA levels, including average fragment sizes, are increased following initiation of CPB in AVR patients, and may be associated with post-operative complications and outcomes. However, larger studies are needed to validate these findings.

Cardiopulmonary bypass associated acute kidney injury: better understanding and better prevention

Cardiopulmonary bypass (CPB) is a common technique in cardiac surgery but is associated with acute kidney injury (AKI), which carries considerable morbidity and mortality. In this review, we explore the range and definition of CPB-associated AKI and discuss the possible impact of different disease recognition methods on research outcomes. Furthermore, we introduce the specialized equipment and procedural intricacies associated with CPB surgeries. Based on recent research, we discuss the potential pathogenesis of AKI that may result from CPB, including compromised perfusion and oxygenation, inflammatory activation, oxidative stress, coagulopathy, hemolysis, and endothelial damage. Finally, we explore current interventions aimed at preventing and attenuating renal impairment related to CPB, and presenting these measures from three perspectives: (1) avoiding CPB to eliminate the fundamental impact on renal function; (2) optimizing CPB by adjusting equipment parameters, optimizing surgical procedures, or using improved materials to mitigate kidney damage; (3) employing pharmacological or interventional measures targeting pathogenic factors.

The Nephroprotective Effect of Nitric Oxide during Extracorporeal Circulation: An Experimental Study

This study aims to determine the effectiveness of administering 80 ppm nitric oxide in reducing kidney injury, mitochondrial dysfunction and regulated cell death in kidneys during experimental perfusion. Twenty-four sheep were randomized into four groups: two groups received 80 ppm NO conditioning with 90 min of cardiopulmonary bypass (CPB + NO) or 90 min of CPB and hypothermic circulatory arrest (CPB + CA + NO), while two groups received sham protocols (CPB and CPB + CA). Kidney injury was assessed using laboratory (neutrophil gelatinase-associated lipocalin, an acute kidney injury biomarker) and morphological methods (morphometric histological changes in kidney biopsy specimens). A kidney biopsy was performed 60 min after weaning from mechanical perfusion. NO did not increase the concentrations of inhaled NO2 and methemoglobin significantly. The NO-conditioning groups showed less severe kidney injury and mitochondrial dysfunction, with statistical significance in the CPB + NO group and reduced tumor necrosis factor-α expression as a trigger of apoptosis and necroptosis in renal tissue in the CPB + CA + NO group compared to the CPB + CA group. The severity of mitochondrial dysfunction in renal tissue was insignificantly lower in the NO-conditioning groups. We conclude that NO administration is safe and effective at reducing kidney injury, mitochondrial dysfunction and regulated cell death in kidneys during experimental CPB.

Whole blood transcriptomics reveals granulocyte colony-stimulating factor as a mediator of cardiopulmonary bypass-induced systemic inflammatory response syndrome

Objectives

Systemic inflammatory response syndrome (SIRS) is a frequent complication of cardiopulmonary bypass (CPB). SIRS is associated with significant morbidity and mortality, but its pathogenesis remains incompletely understood, and as a result, biomarkers are lacking and treatment remains expectant and supportive. This study aimed to understand the pathophysiological mechanisms driving SIRS induced by CPB and identify novel therapeutic targets that might reduce systemic inflammation and improve patient outcomes.

Methods

Twenty-one patients undergoing cardiac surgery and CPB were recruited, and blood was sampled before, during and after surgery. SIRS was defined using the American College of Chest Physicians/Society of Critical Care Medicine criteria. We performed immune cell profiling and whole blood transcriptomics and measured individual mediators in plasma/serum to characterise SIRS induced by CPB.

Results

Nineteen patients fulfilled criteria for SIRS, with a mean duration of 2.7 days. Neutrophil numbers rose rapidly with CPB and remained elevated for at least 48 h afterwards. Transcriptional signatures associated with neutrophil activation and degranulation were enriched during CPB. We identified a network of cytokines governing these transcriptional changes, including granulocyte colony-stimulating factor (G-CSF), a regulator of neutrophil production and function.

Conclusions

We identified neutrophils and G-CSF as major regulators of CPB-induced systemic inflammation. Short-term targeting of G-CSF could provide a novel therapeutic strategy to limit neutrophil-mediated inflammation and tissue damage in SIRS induced by CPB.

Clinicopathological and circulating cell-free DNA profile in myositis associated with anti-mitochondrial antibody

OBJECTIVE

Anti-mitochondrial antibodies (AMAs) are associated with idiopathic inflammatory myopathies (IIMs). We aimed to summarize the clinicopathological characteristics, assess circulating cell-free mitochondrial DNA (ccf-mtDNA), and circulating cell-free nuclear DNA (ccf-nDNA) in AMA-associated IIMs.

METHODS

Medical records of 37 IIMs patients with AMAs were reviewed. Circulating cell-free mtDNA and ccf-nDNA levels in sera from IIMs patients with AMAs (n = 21), disease controls (n = 66) and healthy controls (HCs) (n = 23) were measured and compared. Twenty-eight immune-mediated necrotizing myopathy (IMNM) patients, 23 dermatomyositis (DM) patients, and 15 anti-synthetase syndrome (ASS) patients were enrolled as disease controls. Correlations between variables were analyzed.

RESULTS

Limb weakness was observed in 75.7% and neck weakness in 56.8% of patients. Cardiac involvement occurred in 51.4% of patients. Muscle pathology revealed 81.1% of IMNM, 5.4% polymyositis, and 13.5% nonspecific myositis. Microinfarction was observed in 8.1% of patients. Serum ccf-mtDNA levels in AMA-associated IIMs were significantly higher than those in HCs (p < 0.001), but no significant differences between AMA-associated IIMs and IMNM, DM, or ASS. Serum ccf-nDNA levels in AMA-associated IIMs were significantly higher than those in HCs (p = 0.02), and significantly lower than those in DM (p = 0.02). Serum ccf-nDNA levels correlated negatively with MMT8 total scores (rs = -0.458, p = 0.037) and positively with mRS scores (rs = 0.486, p = 0.025). Serum ccf-nDNA levels were significantly higher in the non-remission group (p < 0.01).

INTERPRETATION

AMA-associated IIMs exhibit distinct clinicopathological features. Serum ccf-nDNA may serve as a potential marker for disease severity and prognosis in AMA-associated IIMs.