Multiple organ dysfunction syndrome is characterized by simultaneous multiple organ failure, which is the leading cause of death in acute critically ill patients. However, what mediates multiple ...organ dysfunction syndrome is not fully understood. The discovery of toxic effects by extracellular histones on different individual organs strongly suggests their involvement in multiple organ dysfunction syndrome. In this study, we investigate whether circulating histones are major mediators of multiple organ dysfunction syndrome in acute critical illnesses.
Combination of retrospective clinical studies and animal models with intervention.
ICU in a tertiary hospital and research laboratories.
Four hundred and twenty ICU patients, including sepsis (140), severe trauma (63), severe pancreatitis (89), and other admission diagnoses (128).
Cells from major organs are treated with calf thymus histones or histone-containing sera. Animal models for sepsis, trauma, and acute pancreatitis are treated with antihistone reagents.
Antihistone reagents in in vitro, ex vivo, and animal models.
Retrospective analysis of a prospectively recruited ICU cohort demonstrated a strong correlation between circulating histones and organ injury markers and Sequential Organ Failure Assessment scores. Ex vivo experiments showed that patient sera containing high histone levels were toxic to cultured cells from different origins, suggesting their universal toxicity to multiple organs. Animal models of sepsis, trauma, and pancreatitis further demonstrated a temporal correlation between histone levels and disease severity and multiple organ injury. Importantly, antihistone reagents, that is, antihistone single-chain variable fragment and nonanticoagulant heparin, could dramatically reduce multiple organ injury, particularly of the heart and lungs, and improve survival in mouse models.
High levels of circulating histones are major mediators of multiple organ dysfunction syndrome. Our results indicate that monitoring upon ICU admission could inform on disease severity and developing antihistone therapy holds great potential of reducing multiple organ dysfunction syndrome and improving survival of critically ill patients.
Acute lung injury is a common complication after severe trauma, which predisposes patients to multiple organ failure. This syndrome largely accounts for the late mortality that arises and despite ...many theories, the pathological mechanism is not fully understood. Discovery of histone-induced toxicity in mice presents a new dimension for elucidating the underlying pathophysiology.
To investigate the pathological roles of circulating histones in trauma-induced lung injury.
Circulating histone levels in patients with severe trauma were determined and correlated with respiratory failure and Sequential Organ Failure Assessment (SOFA) scores. Their cause-effect relationship was studied using cells and mouse models.
In a cohort of 52 patients with severe nonthoracic blunt trauma, circulating histones surged immediately after trauma to levels that were toxic to cultured endothelial cells. The high levels were significantly associated with the incidence of acute lung injury and SOFA scores, as well as markers of endothelial damage and coagulation activation. In in vitro systems, histones damaged endothelial cells, stimulated cytokine release, and induced neutrophil extracellular trap formation and myeloperoxidase release. Cellular toxicity resulted from their direct membrane interaction and resultant calcium influx. In mouse models, cytokines and markers for endothelial damage and coagulation activation significantly increased immediately after trauma or histone infusion. Pathological examinations showed that lungs were the predominantly affected organ with edema, hemorrhage, microvascular thrombosis, and neutrophil congestion. An anti-histone antibody could reduce these changes and protect mice from histone-induced lethality.
This study elucidates a new mechanism for acute lung injury after severe trauma and proposes that circulating histones are viable therapeutic targets for improving survival outcomes in patients.
Summary
The COVID‐19 pandemic has been the most significant health crisis in recent global history. Early studies from Wuhan highlighted COVID‐19‐associated coagulopathy and a significant association ...with mortality was soon recognised. As research continues across the world, more evidence is emerging of the cross‐talk between the innate immune system, coagulation activation and inflammation. Immunothrombosis has been demonstrated to play a key role in the pathophysiology of severe COVID‐19, with extracellular histones and neutrophil extracellular traps detected in the plasma and cardiopulmonary tissues of critically ill patients. Targeting the components of immunothrombosis is becoming an important factor in the treatment of patients with COVID‐19 infection. Recent studies report outcomes of intermediate and therapeutic anticoagulation in hospitalised patients with varying severities of COVID‐19 disease, including optimal dosing and associated bleeding risks. Immunomodulatory therapies, including corticosteroids and IL‐6 receptor antagonists, have been demonstrated to significantly reduce mortality in COVID‐19 patients. As the pandemic continues, more studies are required to understand the driving factors and upstream mechanisms for coagulopathy and immunothrombosis in COVID‐19, and thus potentially develop more targeted therapies for SARS‐CoV‐2 infection, both in the acute phase and in those who develop longer‐term symptom burden.
Streptococcus pneumoniae accounts for more deaths worldwide than any other single pathogen through diverse disease manifestations including pneumonia, sepsis and meningitis. Life-threatening acute ...cardiac complications are more common in pneumococcal infection compared to other bacterial infections. Distinctively, these arise despite effective antibiotic therapy. Here, we describe a novel mechanism of myocardial injury, which is triggered and sustained by circulating pneumolysin (PLY). Using a mouse model of invasive pneumococcal disease (IPD), we demonstrate that wild type PLY-expressing pneumococci but not PLY-deficient mutants induced elevation of circulating cardiac troponins (cTns), well-recognized biomarkers of cardiac injury. Furthermore, elevated cTn levels linearly correlated with pneumococcal blood counts (r=0.688, p=0.001) and levels were significantly higher in non-surviving than in surviving mice. These cTn levels were significantly reduced by administration of PLY-sequestering liposomes. Intravenous injection of purified PLY, but not a non-pore forming mutant (PdB), induced substantial increase in cardiac troponins to suggest that the pore-forming activity of circulating PLY is essential for myocardial injury in vivo. Purified PLY and PLY-expressing pneumococci also caused myocardial inflammatory changes but apoptosis was not detected. Exposure of cultured cardiomyocytes to PLY-expressing pneumococci caused dose-dependent cardiomyocyte contractile dysfunction and death, which was exacerbated by further PLY release following antibiotic treatment. We found that high PLY doses induced extensive cardiomyocyte lysis, but more interestingly, sub-lytic PLY concentrations triggered profound calcium influx and overload with subsequent membrane depolarization and progressive reduction in intracellular calcium transient amplitude, a key determinant of contractile force. This was coupled to activation of signalling pathways commonly associated with cardiac dysfunction in clinical and experimental sepsis and ultimately resulted in depressed cardiomyocyte contractile performance along with rhythm disturbance. Our study proposes a detailed molecular mechanism of pneumococcal toxin-induced cardiac injury and highlights the major translational potential of targeting circulating PLY to protect against cardiac complications during pneumococcal infections.
Neutrophil extracellular traps (NETs) are important in the host defense against infection, but they also promote intravascular coagulation and multiorgan failure in animal models. Their clinical ...significance remains unclear, and available assays for patient care lack specificity and reliability.
To establish a novel assay and test its clinical significance.
A prospective cohort of 341 consecutive adult ICU patients was recruited. The NET-forming capacity of ICU admission blood samples was semiquantified by directly incubating patient plasma with isolated neutrophils
. The association of NET-forming capacity with Sequential Organ Failure Assessment scores, disseminated intravascular coagulation, and 28-day mortality was analyzed and compared with available NET assays.
Using the novel assay, we could stratify ICU patients into four groups with absent (22.0%), mild (49.9%), moderate (14.4%), and strong (13.8%) NET formation, respectively. Strong NET formation was predominantly found in sepsis (
< 0.0001). Adjusted by Acute Physiology and Chronic Health Evaluation II score, multivariate regression showed that the degree of NET formation could independently predict disseminated intravascular coagulation and mortality, whereas other NET assays (e.g., cell-free DNA, myeloperoxidase, and myeloperoxidase-DNA complexes) could not. IL-8 concentrations were found to be strongly associated with NET formation, and inhibiting IL-8 significantly attenuated NETosis. Mitogen-activated protein kinase activation by IL-8 has been identified as a major pathway of NET formation in patients.
This assay directly measures the NET-forming capacity in patient plasma. This could guide clinical management and enable identification of NET-inducing factors in individual patients for targeted treatment and personalized ICU medicine.
Thrombin generation is pivotal to both physiological blood clot formation and pathological development of disseminated intravascular coagulation (DIC). In critical illness, extensive cell damage can ...release histones into the circulation, which can increase thrombin generation and cause DIC, but the molecular mechanism is not clear. Typically, thrombin is generated by the prothrombinase complex, comprising activated factor X (FXa), activated cofactor V (FVa), and phospholipids to cleave prothrombin in the presence of calcium. In this study, we found that in the presence of extracellular histones, an alternative prothrombinase could form without FVa and phospholipids. Histones directly bind to prothrombin fragment 1 (F1) and fragment 2 (F2) specifically to facilitate FXa cleavage of prothrombin to release active thrombin, unlike FVa, which requires phospholipid surfaces to anchor the classical prothrombinase complex. In vivo, histone infusion into mice induced DIC, which was significantly abrogated when prothrombin F1 + F2 were infused prior to histones, to act as decoy. In a cohort of intensive care unit patients with sepsis (n = 144), circulating histone levels were significantly elevated in patients with DIC. These data suggest that histone-induced alternative prothrombinase without phospholipid anchorage may disseminate intravascular coagulation and reveal a new molecular mechanism of thrombin generation and DIC development. In addition, histones significantly reduced the requirement for FXa in the coagulation cascade to enable clot formation in factor VIII (FVIII)- and FIX-deficient plasma, as well as in FVIII-deficient mice. In summary, this study highlights a novel mechanism in coagulation with therapeutic potential in both targeting systemic coagulation activation and correcting coagulation factor deficiency.
Sepsis was first described by the ancient Greek physicians over 2000 years ago. The pathophysiology of the disease, however, is still not fully understood and hence the mortality rate is still ...unacceptably high due to lack of specific therapies. In the last decade, great progress has been made by shifting the focus of research from systemic inflammatory response syndrome (SIRS) to multiple organ dysfunction syndrome (MODS). Sepsis has been re-defined as infection-induced MODS in 2016. How infection leads to MODS is not clear, but what mediates MODS becomes the major topic in understanding the molecular mechanisms and developing specific therapies. Recently, the mechanism of infection-induced extensive immune cell death which releases a large quantity of damage-associated molecular patterns (DAMPs) and their roles in the development of MODS as well as immunosuppression during sepsis have attracted much attention. Growing evidence supports the hypothesis that DAMPs, including high-mobility group box 1 protein (HMGB1), cell-free DNA (cfDNA) and histones as well as neutrophil extracellular traps (NETs), may directly or indirectly contribute significantly to the development of MODS. Here, we provide an overview of the mechanisms and consequences of infection-induced extensive immune cell death during the development of sepsis. We also propose a pivotal pathway from a local infection to eventual sepsis and a potential combined therapeutic strategy for targeting sepsis.
ABSTRACT
Introduction
The development of functional motor competence (FMC; i.e., neuromuscular coordination and control required to meet a wide range of movement goals) is critical to long-term ...development of health- and performance-related physical capacities (e.g., muscular strength and power, muscular endurance, and aerobic endurance). Secular decline in FMC among U.S. children and adolescents presents current and future challenges for recruiting prospective military personnel to successfully perform the physical demands of military duty. The purpose of the current study was to examine the relationship between FMC and physical military readiness (PMR) in a group of Cadets enrolled in an Army Reserve Officer Training Corps program.
Materials and Methods
Ninety Army Reserve Officer Training Corps Cadets from a southeastern university and a military college in the southeast (females = 22; Mage = 19.5 ± 2.5) volunteered for participation in the study. Cadets performed a battery of eight FMC assessments consisting of locomotor, object projection, and functional coordination tasks. To assess PMR, Cadets performed the Army Combat Fitness Test (ACFT).
Values from all FMC assessments were standardized based on the sample and summed to create a composite FMC score. ACFT scores were assigned to Cadets based upon ACFT scoring standards. We used Pearson correlations to assess the relationships between individual FMC assessment raw scores, FMC composite scores, and total ACFT points. We also evaluated the potential impact of FMC on ACFT in the entire sample and within each gender subgroup using hierarchical linear regression. Finally, we implemented a 3 × 2 chi-squared analysis to evaluate the predictive utility of FMC level on pass/fail results on the ACFT by categorizing Cadets’ composite FMC score into high (≥75th percentile) moderate (≥25th percentile and <75th percentile), and low (<25th percentile) based on the percentile ranks within the sample. ACFT pass/fail results were determined using ACFT standards, requiring a minimum of 60 points on each the ACFT subtests.
Results
FMC composite scores correlated strongly with total ACFT performance (r = 0.762) with individual FMC tests demonstrating weak-to-strong relationships ACFT performance (r = 0.200–0.769). FMC uniquely accounted for 15% (95% CI: −0.07 to 0.36) of the variance in ACFT scores in females (R2 = 0.516, F2,19 = 10.11, P < 0.001) and 26% (95% CI: 0.09–0.43) in males (R2 = 0.385, F2,65 = 20.37, P < 0.001), respectively, above and beyond the impact of age. The 3 × 2 chi-squared analysis demonstrated 74% of those with low, 28% with moderate, and 17% with high FMC failed the ACFT (χ2 1, N = 90 = 27.717, V = 0.555, P < 0.001).
Conclusion
FMC composite scores are strongly correlated with ACFT scores, and low levels of FMC were a strong predictor of ACFT failure. These data support the hypothesis that the development of sufficient FMC in childhood and adolescence may be a critical antecedent for PMR. Efforts to improve FMC in children and adolescents may increase PMR of future military recruits.
Measurement of motor competence is a vital process to advancing knowledge in the field of motor development. As motor competence is being more widely linked to research in other academic domains ...(e.g., public health, neuroscience, behavioral health), it is imperative that measurement methodology and protocols are reproducible with high degrees of validity and reliability. When addressing the plethora of available assessments, mostly developed for youth populations, there are potential questions and concerns that need to be addressed and/or clarified. One of the most prominent issues is the lack of a lifespan measure of motor competence, which is at odds with the premise of the field of motor development-studying changes in motor behavior across the lifespan. We address six areas of concern in lifespan assessment which include: (1) lack of assessment feasibility for conducting research with large samples, (2) lack of accountability for cultural significance of skills assessed, (3) limited sensitivity and discriminatory capabilities of assessments, (4) developmental and ecological validity limitations, (5) a problematic definition of 'success' in skill performance, and (6) task complexity and adaptability limitations. It is important to critically analyze current assessment methodologies as it will help us to envision the development and application of potential new assessments through a more comprehensive lens. Ultimately, we propose that reinvesting in how we think about assessment will be highly beneficial for integrating motor development from a holistic perspective, impact scientific advancements in other developmental domains, and increase global and lifespan surveillance of motor competence.
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