PAMPs and DAMPs as triggers for DIC

The role of the cGAS-STING signaling pathway in viral infections, inflammatory and autoimmune diseases

Pattern recognition receptors are an essential part of the immune system, which detect pathogen-associated molecular patterns (PAMPs) and damage-associated molecular patterns (DAMPs) and help shape both innate and adaptive immune responses. When dsDNA is present, cyclic GMP-AMP Synthase (cGAS) produces a second messenger called cyclic GMP-AMP (cGAMP), which then triggers an adaptor protein called STING, and eventually activates the expression of type I interferon (IFN) and pro-inflammatory cytokines in immune cells. The cGAS-STING signaling pathway has been receiving a lot of attention lately as a key immune-surveillance mediator. In this review, we summarize the present circumstances of the cGAS-STING signaling pathway in viral infections and inflammatory diseases, as well as autoimmune diseases. Modulation of the cGAS-STING signaling pathway provides potential strategies for treating viral infections, inflammatory diseases, and autoimmune diseases.

Multiple sclerosis: the NLRP3 inflammasome, gasdermin D, and therapeutics

Multiple sclerosis (MS) stands as a chronic inflammatory disease characterized by its neurodegenerative impacts on the central nervous system. The complexity of MS and the significant challenges it poses to patients have made the exploration of effective treatments a crucial area of research. Among the various mechanisms under investigation, the role of inflammation in MS progression is of particular interest. Inflammatory responses within the body are regulated by various cellular mechanisms, one of which involves the nucleotide-binding oligomerization domain (NOD)-, leucine-rich repeat (LRR)-, and pyrin domains (PYD)-containing protein 3 (NLRP3). NLRP3 acts as a sensor within cells, playing a pivotal role in controlling the inflammatory response. Its activation is a critical step leading to the assembly of the NLRP3 inflammasome complex, a process that has profound implications for inflammatory diseases like MS. The NLRP3 inflammasome's activation is intricately linked to the subsequent activation of caspase 1 and gasdermin D (GsdmD), signaling pathways that are central to the inflammatory process. GsdmD, a prominent member of the Gasdermin protein family, is particularly noteworthy for its role in pyroptotic cell death, a form of programmed cell death that is distinct from apoptosis and is characterized by its inflammatory nature. This pathway's activation contributes significantly to the pathology of MS by exacerbating inflammatory responses within the nervous system. Given the detrimental effects of unregulated inflammation in MS, therapeutics targeting these inflammatory processes offer a promising avenue for alleviating the symptoms experienced by patients. This review delves into the intricacies of the pyroptotic pathways, highlighting how the formation of the NLRP3 inflammasome induces such pathways and the potential intervention points for therapeutic agents. By inhibiting key steps within these pathways, it is possible to mitigate the inflammatory response, thereby offering relief to those suffering from MS. Understanding these mechanisms not only sheds light on the pathophysiology of MS but also paves the way for the development of novel therapeutic strategies aimed at controlling the disease's progression through the modulation of the body's inflammatory response.

Neonatal hemostasis and the use of thromboelastography/rotational thromboelastometry in the neonatal period

Developmental hemostasis refers to age-related alterations related to the progressive maturation of the hemostatic system. Although the conventional coagulation tests, such as prothrombin time (PT) and activated partial thromboplastin time (aPTT), are indeed helpful in coagulation workup, they do not accurately delineate the hemostasis in vivo. The viscoelastic tests, namely thromboelastography (TEG) and rotational thromboelastometry (ROTEM), seem to reflect hemostasis more accurately since they measure various clot parameters without excluding the cellular coagulation components. TEG and ROTEM have shown redaction in blood product administration when used in therapeutic algorithms in older children and adults, but their use in neonates is limited. This review summarizes the current literature regarding using these tests in the neonatal population. Several studies tried to resolve the lack of neonatal reference values of the TEG/ROTEM parameters by publishing neonatal reference ranges for various gestational age groups. Moreover, few studies concerning therapeutic hypothermia, neonates undergoing surgery, and critically ill neonates have shown some predictive value of these tests regarding bleeding events. Even though their results seem promising, larger studies of higher quality are needed to clarify any discrepancies and point out whether these tests have significant predictive value. In conclusion, viscoelastic tests need to be increasingly part of the NICUs' clinical routine and should be used along with conventional coagulation tests in transfusion therapy.

Damage-Associated Molecular Patterns as Mediators of Thrombus Formation on Dialyzer Membrane in Critically Ill Patients

This prospective study investigated the relationship between inflammation, damage-associated molecular patterns (DAMPs), and thrombus formation on dialyzer membranes in critically ill patients undergoing renal replacement therapy (RRT) from July 2020 to August 2022, identifying mechanisms and interventions to prevent clotting. The patients were divided into two groups: inflammatory (n = 56, serum C-reactive protein >10 mg/dl) and noninflammatory control (n = 45, serum C-reactive protein <5 mg/dl). Cell-free deoxyribonucleic acid (DNA) levels, high mobility group box 1 protein (HMGB1), histone H3, and myeloperoxidase (MPO) in the lumen of the hollow fiber membrane of the dialyzer were quantified. Immunostaining assessed leukocytes, fibrin fibers, and platelet thrombi on the luminal surface of the hollow fiber membrane. The inflammatory group, compared to controls, exhibited elevated cell-free DNA, HMGB1, and MPO levels, although histone H3 remained unchanged. Damage-associated molecular patterns increased with disseminated intravascular coagulation (DIC) severity. Immunostaining in the inflammatory group revealed leukocytes, amorphous nuclei, neutrophil extracellular trap-like structures, fibrin fibers, and platelet thrombi on the hollow fiber membrane's luminal surface. Elevated DAMP levels in severely inflamed patients' dialyzer membranes, correlating with DIC severity, indicate a link between inflammation, coagulation activation, and dialyzer clotting. Research into thrombus prevention in RRT for DIC-affected critically ill patients is warranted.

Sepsis-Induced Coagulopathy: A Comprehensive Narrative Review of Pathophysiology, Clinical Presentation, Diagnosis, and Management Strategies

Physiological hemostasis is a balance between pro- and anticoagulant pathways, and in sepsis, this equilibrium is disturbed, resulting in systemic thrombin generation, impaired anticoagulant activity, and suppression of fibrinolysis, a condition termed sepsis-induced coagulopathy (SIC). SIC is a common complication, being present in 24% of patients with sepsis and 66% of patients with septic shock, and is often associated with poor clinical outcomes and high mortality. 1 , 2 Recent preclinical and clinical studies have generated new insights into the molecular pathogenesis of SIC. In this article, we analyze the complex pathophysiology of SIC with a focus on the role of procoagulant innate immune signaling in hemostatic activation--tissue factor production, thrombin generation, endotheliopathy, and impaired antithrombotic functions. We also review clinical presentations of SIC, the diagnostic scoring system and laboratory tests, the current standard of care, and clinical trials evaluating the efficacies of anticoagulant therapies.

Macrophage-1 antigen exacerbates histone-induced acute lung injury and promotes neutrophil extracellular trap formation

Acute lung injury (ALI), which occurs in association with sepsis, trauma, and coronavirus disease 2019 (COVID-19), is a serious clinical condition with high mortality. Excessive platelet-leukocyte aggregate (PLA) formation promotes neutrophil extracellular trap (NET) release and thrombosis, which are involved in various diseases, including ALI. Macrophage-1 antigen (Mac-1, CD11b/CD18), which is expressed on the surface of leukocytes, is known to promote NET formation. This study aimed to elucidate the role of Mac-1 in extracellular histone-induced ALI. Exogenous histones were administered to Mac-1-deficient mice and wild-type (WT) mice with or without neutrophil or platelet depletion, and several parameters were investigated 1 h after histone injection. Depletion of neutrophils or platelets improved survival time and macroscopic and microscopic properties of lung tissues, and decreased platelet-leukocyte formation and plasma myeloperoxidase levels. These improvements were also observed in Mac-1-/- mice. NET formation in Mac-1-/- bone marrow neutrophils (BMNs) was significantly lower than that in WT BMNs. In conclusion, our findings suggest that Mac-1 is associated with exacerbation of histone-induced ALI and the promotion of NET formation in the presence of activated platelets.

The heart-bone connection: relationships between myocardial infarction and osteoporotic fracture

Myocardial infarction (MI) and osteoporotic fracture (Fx) are two of the leading causes of mortality and morbidity worldwide. Although these traumatic injuries are treated as if they are independent, there is epidemiological evidence linking the incidence of Fx and MI, thus raising the question of whether each of these events can actively influence the risk of the other. Atherosclerotic cardiovascular disease and osteoporosis, the chronic conditions leading to MI and Fx, are known to have shared pathoetiology. Furthermore, sustained systemic inflammation after traumas such as MI and Fx has been shown to exacerbate both underlying chronic conditions. However, the effects of MI and Fx outside their own system have not been well studied. The sympathetic nervous system (SNS) and the complement system initiate a systemic response after MI that could lead to subsequent changes in bone remodeling through osteoclasts. Similarly, SNS and complement system activation following fracture could lead to heart tissue damage and exacerbate atherosclerosis. To determine whether damaging bone-heart cross talk may be important comorbidity following Fx or MI, this review details the current understanding of bone loss after MI, cardiovascular damage after Fx, and possible shared underlying mechanisms of these processes.

Value function assessment to different RL algorithms for heparin treatment policy of patients with sepsis in ICU

Heparin is a critical aspect of managing sepsis after abdominal surgery, which can improve microcirculation, protect organ function, and reduce mortality. However, there is no clinical evidence to support decision-making for heparin dosage. This paper proposes a model called SOFA-MDP, which utilizes SOFA scores as states of MDP, to investigate clinic policies. Different algorithms provide different value functions, making it challenging to determine which value function is more reliable. Due to ethical restrictions, we cannot test all policies on patients. To address this issue, we proposed two value function assessment methods: action similarity rate and relative gain. We experimented with heparin treatment policies for sepsis patients after abdominal surgery using MIMIC-IV. In the experiments, TD(0) shows the most reliable performance. Using the action similarity rate and relative gain to assess AI policy from TD(0), the agreement rates between AI policy and "good" physician's actual treatment are 64.6% and 73.2%, while the agreement rates between AI policy and "bad" physician's actual treatment are 44.1% and 35.8%, the gaps are 20.5% and 37.4%, respectively. External validation using action similarity rate and relative gain based on eICU resulted in agreement rates of 61.5% and 69.1% with the "good" physician's treatment, and 45.2% and 38.3% with the "bad" physician's treatment, with gaps of 16.3% and 30.8%, respectively. In conclusion, the model provides instructive support for clinical decisions, and the evaluation methods accurately distinguish reliable and unreasonable outcomes.

Differential Gene Expression and Immune Cell Infiltration in Patients with Steroid-induced Necrosis of the Femoral Head

OBJECTIVE

The study aimed to study the differential gene expression and immune cell infiltration in patients with steroid-induced necrosis of the femoral head (SANFH), identify the key genes and immune cells of SANFH, and explore the relationship between immune cells and SANFH.

METHODS

The high-throughput gene chip dataset GSE123568 was downloaded from the GEO database, and the differential gene expression was analyzed with the R language. The STRING database and Cytoscape software were used to analyze the protein interaction network and screen key genes, and enrichment analysis was carried out on key genes. The infiltration of immune cells in SANFH patients was analyzed and verified by immunohistochemistry.

RESULTS

EP300, TRAF6, STAT1, JAK1, CASP8, and JAK2 are key genes in the pathogenesis of SANFH, which mainly involve myeloid cell differentiation, cytokine-mediated signaling pathway, tumor necrosis factor-mediated signaling pathway, and cellular response to tumor necrosis factor through JAK-STAT, NOD-like receptor, toll-like receptor, and other signaling pathways, leading to the occurrence of diseases; immune infiltration and immunohistochemical results have shown the expression of memory B cells and activated dendritic cells as reduced in SANFH patients, while in the same SANFH samples, M1 macrophages have been positively correlated with monocytes, and neutrophils have been negatively correlated with monocytes expression.

CONCLUSION

EP300, TRAF6, STAT1, JAK1, CASP8, and JAK2 have exhibited significant differences in SANFH (spontaneous osteonecrosis of the femoral head). Memory B cells, activated dendritic cells, M1 macrophages, monocytes, and neutrophils have shown abnormal expression in SANFH.

A Molecular Troika of Angiogenesis, Coagulopathy and Endothelial Dysfunction in the Pathology of Avascular Necrosis of Femoral Head: A Comprehensive Review

Avascular necrosis of the femoral head (ANFH) is a painful disorder characterized by the cessation of blood supply to the femoral head, leading to its death and subsequent joint collapse. Influenced by several risk factors, including corticosteroid use, excessive alcohol intake, hypercholesterolemia, smoking and some inflammatory disorders, along with cancer, its clinical consequences are thrombus formation due to underlying inflammation and endothelial dysfunction, which collaborates with coagulopathy and impaired angiogenesis. Nonetheless, angiogenesis resolves the obstructed free flow of the blood by providing alternative routes. Clinical manifestations of early stage of ANFH mimic cysts or lesions in subchondral bone, vasculitis and transient osteoporosis of the hip, rendering it difficult to diagnose, complex to understand and complicated to cure. To date, the treatment methods for ANFH are controversial as no foolproof curative strategy is available, and these depend upon different severity levels of the ANFH. From an in-depth understanding of the pathological determinants of ANFH, it is clear that impaired angiogenesis, coagulopathy and endothelial dysfunction contribute significantly. The present review has set two aims, firstly to examine the role and relevance of this molecular triad (impaired angiogenesis, coagulopathy and endothelial dysfunction) in ANFH pathology and secondly to propose some putative therapeutic strategies, delineating the fact that, for the better management of ANFH, a combined strategy to curtail this molecular triangle must be composed rather than focusing on individual contributions.

Damage-associated molecular patterns and fibrinolysis perturbation are associated with lethal outcomes in traumatic injury

BACKGROUND

Upon cellular injury, damage-associated molecular patterns (DAMPs) are released into the extracellular space and evoke proinflammatory and prothrombotic responses in animal models of sterile inflammation. However, in clinical settings, the dynamics of DAMP levels after trauma and links between DAMPs and trauma-associated coagulopathy remain largely undetermined.

METHODS

Thirty-one patients with severe trauma, who were transferred to Kagoshima City Hospital between June 2018 and December 2019, were consecutively enrolled in this study. Blood samples were taken at the time of delivery, and 6 and 12 h after the injury, and once daily thereafter. The time-dependent changes of coagulation/fibrinolysis markers, including thrombin-antithrombin complex, α2-plasmin inhibitor (α2-PI), plasmin-α2-PI complex, and plasminogen activator inhibitor-1 (PAI-1), and DAMPs, including high mobility group box 1 and histone H3, were analyzed. The relationship between coagulation/fibrinolysis markers, DAMPs, Injury Severity Score, in-hospital death, and amount of blood transfusion were analyzed.

RESULTS

The activation of coagulation/fibrinolysis pathways was evident at the time of delivery. In contrast, PAI-1 levels remained low at the time of delivery, and then were elevated at 6-12 h after traumatic injury. Histone H3 and high mobility group box 1 levels were elevated at admission, and gradually subsided over time. PAI-1 levels at 6 h were associated with serum histone H3 levels at admission. Increased histone H3 levels and plasmin-α2-PI complex levels were associated with in-hospital mortality. α2-PI levels at admission showed the strongest negative correlation with the amount of blood transfusion.

CONCLUSION

The elevation of histone H3 levels and fibrinolysis perturbation are associated with fatal outcomes in patients with traumatic injury. Patients with low α2-PI levels at admission tend to require blood transfusion.

Defining the metabolic signatures associated with human macrophage polarisation

Macrophages are essential components of the innate immune system that play both homeostatic roles in healthy organs, and host defence functions against pathogens after tissue injury. To accomplish their physiological role, macrophages display different profiles of gene expression, immune function, and metabolic phenotypes that allow these cells to participate in different steps of the inflammatory reaction, from the initiation to the resolution phase. In addition, significant differences exist in the phenotype of macrophages depending on the tissue in which they are present and on the mammalian species. From a metabolic point of view, macrophages are essentially glycolytic cells; however, their metabolic fluxes are dependent on the functional polarisation of these cells. This metabolic and cellular plasticity offers the possibility to interfere with the activity of macrophages to avoid harmful effects due to persistent activation or the release of molecules that delay tissue recovery after injury.

Reduction of neutrophil extracellular traps accelerates inflammatory resolution and increases bone formation on titanium implants

Neutrophils are the most abundant immune cells in the blood and the first cells to be recruited to the biomaterial implantation site. Neutrophils are fundamental in recruiting mononuclear leukocytes to mount an immune response at the injury site. Neutrophils exert significant pro-inflammatory effects through the release of cytokines and chemokines, degranulation and release of myeloperoxidase (MPO) and neutrophil elastase (NE), and the production of large DNA-based networks called neutrophil extracellular traps (NETs). Neutrophils are initially recruited and activated by cytokines and pathogen- and damage-associated molecular patterns, but little is known about how the physicochemical composition of the biomaterial affects their activation. This study aimed to understand how ablating neutrophil mediators (MPO, NE, NETs) affected macrophage phenotype in vitro and osseointegration in vivo. We discovered that NET formation is a crucial mediator of pro-inflammatory macrophage activation, and inhibition of NET formation significantly suppresses macrophage pro-inflammatory phenotype. Furthermore, reducing NET formation accelerated the inflammatory phase of healing and produced greater bone formation around the implanted biomaterial, suggesting that NETs are essential regulators of biomaterial integration. Our findings emphasize the importance of the neutrophil response to implanted biomaterials and highlight innate immune cells' regulation and amplification signaling during the initiation and resolution of the inflammatory phase of biomaterial integration. STATEMENT OF SIGNIFICANCE: Neutrophils are the most abundant immune cells in blood and are the first to be recruited to the injury/implantation site where they exert significant pro-inflammatory effects. This study aimed to understand how ablating neutrophil mediators affected macrophage phenotype in vitro and bone apposition in vivo. We found that NET formation is a crucial mediator of pro-inflammatory macrophage activation. Reducing NET formation accelerated the inflammatory phase of healing and produced greater appositional bone formation around the implanted biomaterial, suggesting that NETs are essential regulators of biomaterial integration.

Effects of recombinant human soluble thrombomodulin on neutrophil extracellular traps in the kidney of a mouse model of endotoxin shock

OBJECTIVES

Sepsis is a life-threatening condition characterized by multi-organ dysfunction due to host immune system dysregulation in response to an infection. During sepsis, neutrophils release neutrophil extracellular traps (NETs) as part of the innate immune response. However, excessive NETs play a critical role in the development of organ failure during sepsis. Although recombinant human soluble thrombomodulin (rTM) can inhibit NET formation in the lungs and liver of a mouse model of endotoxin shock, its effects on the kidneys are unclear.

METHODS

The specific effects of NETs and rTM on the renal cortex and renal medulla were examined in a mouse model of endotoxin shock generated by intraperitoneal (i.p.) injection of lipopolysaccharide (LPS), followed by i.p. injection of rTM or an identical volume of saline 1 h later.

RESULTS

LPS injection increased serum creatinine, blood urea nitrogen, and histone H3 levels. However, rTM administration significantly decreased histone H3 and citrullinated histone H3 (citH3) levels. Immunohistochemical analysis revealed no significant changes in citH3 quantity in the renal cortex of any group. However, in the renal medulla, the increase in citH3 induced by LPS was abolished in the LPS+rTM group.

CONCLUSIONS

Our findings demonstrate that rTM can suppress NETs in the renal medulla of mice with endotoxin-induced acute kidney injury.

Extracellular histones as damage-associated molecular patterns in neuroinflammatory responses

The four core histones H2A, H2B, H3, H4, and the linker histone H1 primarily bind DNA and regulate gene expression within the nucleus. Evidence collected mainly from the peripheral tissues illustrates that histones can be released into the extracellular space by activated or damaged cells. In this article, we first summarize the innate immune-modulatory properties of extracellular histones and histone-containing complexes, such as nucleosomes, and neutrophil extracellular traps (NETs), described in peripheral tissues. There, histones act as damage-associated molecular patterns (DAMPs), which are a class of endogenous molecules that trigger immune responses by interacting directly with the cellular membranes and activating pattern recognition receptors (PRRs), such as toll-like receptors (TLR) 2, 4, 9 and the receptor for advanced glycation end-products (RAGE). We then focus on the available evidence implicating extracellular histones as DAMPs of the central nervous system (CNS). It is becoming evident that histones are present in the brain parenchyma after crossing the blood-brain barrier (BBB) or being released by several types of brain cells, including neurons, microglia, and astrocytes. However, studies on the DAMP-like effects of histones on CNS cells are limited. For example, TLR4 is the only known molecular target of CNS extracellular histones and their interactions with other PRRs expressed by brain cells have not been observed. Nevertheless, extracellular histones are implicated in the pathogenesis of a variety of neurological disorders characterized by sterile neuroinflammation; therefore, detailed studies on the role these proteins and their complexes play in these pathologies could identify novel therapeutic targets.

Anti-inflammatory activities of flavonoid derivates

Background and purpose

Flavonoids are a group of phytochemicals found abundantly in various plants. Scientific evidence has revealed that flavonoids display potential biological activities, including their ability to alleviate inflammation. This activity is closely related to their action in blocking the inflammatory cascade and inhibiting the production of pro-inflammatory factors. However, as flavonoids typically have poor bioavailability and pharmacokinetic profile, it is quite challenging to establish these compounds as a drug. Nevertheless, progressive advancements in drug delivery systems, particularly in nanotechnology, have shown promising approaches to overcome such challenges.

Review approach

This narrative review provides an overview of scientific knowledge about the mechanism of action of flavonoids in the mitigation of inflammatory reaction prior to delivering a comprehensive discussion about the opportunity of the nanotechnology-based delivery system in the preparation of the flavonoid-based drug.

Key results

Various studies conducted in silico, in vitro, in vivo, and clinical trials have deciphered that the anti-inflammatory activities of flavonoids are closely linked to their ability to modulate various biochemical mediators, enzymes, and signalling pathways involved in the inflammatory processes. This compound could be encapsulated in nanotechnology platforms to increase the solubility, bioavailability, and pharmacological activity of flavonoids as well as reduce the toxic effects of these compounds.

Conclusion

In Summary, we conclude that flavonoids and their derivates have given promising results in their development as new anti-inflammatory drug candidates, especially if they formulate in nanoparticles.

Cytokine hemoadsorption with CytoSorb® in patients with sepsis: a systematic review and meta-analysis

OBJECTIVE

To analyze the effect of CytoSorb® on mortality, interleukin levels, vasopressor use and adverse events in patients with sepsis.

METHODS

We searched MEDLINE®, Embase and the Cochrane Library for randomized controlled trials and cohort studies that reported the use of CytoSorb® among septic patients. The primary outcome was mortality, and secondary outcomes included the use of vasopressors, levels of inflammatory markers, predicted versus observed mortality, length of stay in the intensive care unit, and adverse events.

RESULTS

We included 6 studies enrolling 413 patients, and assessment for risk of bias indicated variations in study quality from high to moderate. The overall mortality rate was 45%, and no significant effect on mortality was found at 28 - 30 days (RR 0.98 [0.12 - 8.25] for the randomized clinical trial and RR 0.74 [0.49 - 1.13] for cohort studies). We did not perform a metanalysis for other outcomes due to the small number of studies found or the lack of data.

CONCLUSION

Our study found very low certainty evidence, due to imprecision, risk of bias, and heterogeneity, thereby showing no benefit of CytoSorb® use in terms of mortality at 28 - 30 days. We cannot recommend the use of CytoSorb® in septic or septic shock patients outside clinical trials. Further high-quality randomized trials with a common intervention arm are needed to evaluate the influence of CytoSorb® in this population.

PROSPERO REGISTER

CRD42021262219.

Sepsis-induced disseminated intravascular coagulation: an international estrangement of disease concept

Disseminated intravascular coagulation (DIC) is an acquired syndrome characterized by widespread intravascular activation of coagulation, which can be caused by infectious and noninfectious insults, such as trauma, postcardiac arrest syndrome, and malignant diseases. At present, diagnosis and treatment of DIC clearly differ between Japan and Western countries; in Japan, DIC has long been considered a therapeutic target, and much evidence on DIC has been published. However, there has recently been no international consensus on whether DIC should be a therapeutic target with anticoagulant therapy. This review describes the coagulofibrinolytic system abnormalities associated with sepsis and discusses related management strategies. It also explores the reasons why DIC is perceived differently in different regions. There is a major discrepancy between diagnostic and treatment options in Japan, which are based on holistic assessments of trials, as well as the results of post hoc subgroup analyses and observational studies, and those in Western countries, which are based mainly on the results of sepsis mega trials, especially randomized controlled trials. The differences might also be due to various patient factors in each region, especially racial characteristics in thrombolytic mechanisms, and differences in interpretation of evidence for candidate drugs. Hence, Japanese researchers need to distribute their high-quality clinical research data not only to Japan but also to the rest of the world.

On Peri-Implant Bone Loss Theories: Trying To Piece Together the Jigsaw

This review aims to explore the plausibility of new theories on the etiopathogenesis of marginal bone loss (MBL) and peri-implantitis (PI) and to discuss possible underlying pathogenic mechanisms. The former concept of osteointegration of dental implants can now be conceptualized as a foreign body response histologically characterized by a bony demarcation in combination with chronic inflammation. Different risk factors can provoke additional inflammation and, therefore, pro-inflammatory cytokine release in soft tissues and bone, leading to an overpass of the threshold of peri-implant bone defensive and regenerative capacity. Progressive bone loss observed in MBL and PI is ultimately due to a localized imbalance in the receptor activator of nuclear factor kappaB ligand (RANKL)/Receptor activator of nuclear factor κ B (RANK)/osteoprotegerin (OPG) pathway in favor of increased catabolic activity. The genetic background and the severity and duration of the risk factors could explain differences between individuals in the threshold needed to reach an imbalanced scenario. MBL and PI pathogenesis could be better explained by the "inflammation-immunological balance" theory rather than a solely "infectious disease" conception. The link between the effect of biofilm and other risk factors leading to an imbalanced foreign body response lies in osteoclast differentiation and activation pathways (over)stimulation.

Innate immune TLR7 signaling mediates platelet activation and platelet-leukocyte aggregate formation in murine bacterial sepsis

Thrombocytopenia is a common complication in sepsis and is associated with higher mortality. Activated platelets express CD62P, which facilitates platelet-leukocyte aggregate (PLA) formation and contributes to thrombocytopenia in sepsis. We have reported that thrombocytopenia in murine sepsis is partly attributable to TLR7 signaling, but the underlying mechanism is unclear. In the current study, we tested the hypothesis that TLR7 mediates platelet activation and PLA formation during sepsis. In vitro, whole blood from WT mice treated with loxoribine, a TLR7 agonist, exhibited a dose-dependent increase in activated platelets compared to the control (PBS with 0.05% DMSO) or loxoribine-treated TLR7^-/- whole blood. In a murine model of sepsis, there was a significant increase in platelet activation and PLA formation 24 hours after cecal ligation and puncture (CLP) as evidenced by double positive expression of CD41⁺/CD62P⁺ and CD45⁺/CD62P⁺, respectively. The sepsis-induced PLA formation was significantly attenuated in TLR7^-/- mice. Finally, in ex-vivo experiments, plasma isolated from septic mice induced WT platelet activation, but such effect was significantly attenuated in platelets deficient of TLR7. These findings demonstrate a pivotal role of TLR7 signaling in platelet activation and PLA formation during bacterial sepsis.

Early prophylactic anticoagulation with heparin alleviates mortality in critically ill patients with sepsis: a retrospective analysis from the MIMIC-IV database

Background

Minimal data exist on anticoagulation use and timing and the dose of heparin in patients with sepsis, and whether heparin use improves sepsis survival remains largely unclear. This study was performed to assess whether heparin administration would provide a survival advantage in critically ill patients with sepsis.

Methods

A retrospective cohort study of patients with sepsis in the Medical Information Mart for Intensive Care (MIMIC)-IV database was conducted. Cox proportional hazards model and propensity score matching (PSM) were used to evaluate the outcomes of prophylactic anticoagulation with heparin administered by subcutaneous injection within 48 h of intensive care unit (ICU) admission. The primary outcome was in-hospital mortality. Secondary outcomes included 60-day mortality, length of ICU stay, length of hospital stay and incidence of acute kidney injury (AKI) on day 7. E-Value analysis were used for unmeasured confounding.

Results

A total of 6646 adult septic patients were included and divided into an early prophylactic heparin group (n = 3211) and a nonheparin group (n = 3435). In-hospital mortality in the heparin therapy group was significantly lower than that in the nonheparin group (prematched 14.7 vs 20.0%, hazard ratio (HR) 0.77, 95% confidence interval (CI) [0.68-0.87], p < 0.001, and postmatched 14.9 vs 18.3%, HR 0.78, 95% CI [0.68-0.89], p < 0.001). Secondary endpoints, including 60-day mortality and length of ICU stay, differed between the heparin and nonheparin groups (p < 0.01). Early prophylactic heparin administration was associated with in-hospital mortality among septic patients in different adjusted covariates (HR 0.71-0.78, p < 0.001), and only administration of five doses of heparin was associated with decreased in-hospital mortality after PSM (HR 0.70, 95% CI 0.56-0.87, p < 0.001). Subgroup analysis showed that heparin use was significantly associated with reduced in-hospital mortality in patients with sepsis-induced coagulopathy, septic shock, sequential organ failure assessment score ≥ 10, AKI, mechanical ventilation, gram-positive bacterial infection and gram-negative bacterial infection, with HRs of 0.74, 0.70, 0.58, 0.74, 0.73, 0.64 and 0.72, respectively (p <0.001). E-Value analysis suggested robustness to unmeasured confounding.

Conclusions

This study found an association between early administration prophylactic heparin provided to patients with sepsis and reduced risk-adjusted mortality. A prospective randomized-controlled study should be designed to further assess the relevant findings.

Aging hampers neutrophil extracellular traps (NETs) efficacy

Background

NETosis is a neutrophil-mediated defense mechanism during which DNA and enzymes are extruded forming a network (NETs) trapping and killing different pathogens. NETosis is reduced in both mice and humans during aging.

Aims

We explored the difference in the efficacy of NETs released in elderly (> 65 years) versus adults (20–50 years) subjects in inhibiting Staphylococcus aureus growth and activating the growth of keratinocytes.

Methods

Neutrophil granulocytes, obtained from venous blood both in healthy elderly and adult subjects, were stimulated by LPS (0–250 µg/ml) to induce the formation of NET. NETs were quantified by SYBR Green staining and growth inhibition of S. aureus was evaluated by disk diffusion test. Furthermore, NETs (0–500 ng/ml) were added to immortalized human keratinocytes (HaCaT cells), and their proliferation was evaluated by MTT assay after 24 h. Finally, the DNA size of NETs was evaluated by flow cytometry after SYBR Green staining.

Results

Greater production of NETs was observed in elderly subjects than in adults, but these NETs showed reduced bactericidal capacity and HaCaT cells’ proliferation stimulation. The activities of the NETs are related to the size of the extruded DNA threads, and when NETs size was analyzed, DNA from elderly showed a higher size compared to that obtained by adults.

Discussion

Unexpected results showed aging-related NETs structural modification resulting in both a lower antimicrobial activity and keratinocyte proliferation stimulation compared to NETs obtained from adults.

Conclusions

The NETs DNA size observed in elderly subjects has not been previously reported and could be part of other pathogenic mechanisms observed in aging.

Prognostic value of serum high mobility group box 1 protein and histone H3 levels in patients with disseminated intravascular coagulation: a multicenter prospective cohort study

Background

We compared the prognostic value of serum high mobility group box 1 protein (HMGB1) and histone H3 levels with the International Society on Thrombosis and Haemostasis (ISTH) disseminated intravascular coagulation (DIC) scores for 28-day in-hospital mortality in patients with DIC caused by various underlying diseases.

Methods

We conducted a multicenter prospective cohort study including two hematology departments, four emergency departments, and one general medicine department in Japan, between August 2017 and July 2021. We included patients diagnosed with DIC by the ISTH DIC scoring system.

Results

Overall, 104 patients were included: 50 with hematopoietic disorders, 41 with infections, and 13 with the other diseases. The 28-day in-hospital mortality rate was 21%. The receiver operator characteristic (ROC) curve showed that a DIC score of 6 points, serum HMGB1 level of 8 ng/mL, and serum histone H3 level of 2 ng/mL were the optimal cutoff points. The odds ratios of more than these optimal cutoff points of the DIC score, serum HMGB1, and histone H3 levels were 1.58 (95% confidence interval [CI]: 0.60 to 4.17, p = 0.36), 5.47 (95% CI: 1.70 to 17.6, p = 0.004), and 9.07 (95% CI: 2.00 to 41.3, p = 0.004), respectively. The area under the ROC curve of HMGB1 (0.74, 95% CI: 0.63 to 0.85) was better than that of the ISTH DIC scores (0.55, 95% CI: 0.43 to 0.67, p = 0.03), whereas that of histone H3 was not (0.71, 95% CI: 0.60 to 0.82, p = 0.07). Calibration and net reclassification plots of HMGB1 identified some high-risk patients, whereas the ISTH DIC scores and histone H3 did not. The category-free net reclassification improvement of HMGB1 was 0.45 (95% CI: 0.01 to 0.90, p = 0.04) and that of histone H3 was 0.37 (95% CI: − 0.05 to 0.78, p = 0.08).

Conclusions

Serum HMGB1 levels have a prognostic value for mortality in patients with DIC. This finding may help physicians develop treatment strategies.

Supplementary Information

The online version contains supplementary material available at 10.1186/s12959-022-00390-2.

Pathophysiology of COVID-19: Critical Role of Hemostasis

The COVID-19 pandemic, caused by SARS-CoV-2, had its first cases identified in late 2019 and was considered a clinical pandemic in March 2020. In March 2022, more than 500 million people were infected and 6,2 million died as a result of this disease, increasingly associated with changes in human hemostasis, such as hypercoagulation. Numerous factors contribute to the hypercoagulable state, and endothelial dysfunction is the main one, since the activation of these cells can strongly activate platelets and the coagulation system. In addition, there is a dysregulation of the renin-angiotensin system due to the SARS-CoV-2 takeover of the angiotensin converting enzyme 2, resulting in a strong immune response that could further damage the endothelium. Thrombus formation in the pulmonary microvasculature structure in patients with COVID-19 is an important factor to determine the severity of the clinical picture and the outcome of this disease. This review describes the hemostatic changes that occur in SARS-CoV-2 infection, to further improve our understanding of pathogenic mechanisms and the interaction between endothelium dysfunction, kallikrein-kinins, renin angiotensin, and the Coagulation/fibrinolysis systems as underlying COVID-19 effectors. This knowledge is crucial for the development of new effective therapeutic approaches, attenuating the severity of SARS-CoV-2’s infection and to reduce the deaths.

A comprehensive review about immune responses and exhaustion during coronavirus disease (COVID-19)

Coronavirus disease (COVID-19) is a viral infectious disease caused by the severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) virus. The infection was reported in Wuhan, China, in late December 2019 and has become a major global concern due to severe respiratory infections and high transmission rates. Evidence suggests that the strong interaction between SARS-CoV-2 and patients' immune systems leads to various clinical symptoms of COVID-19. Although the adaptive immune responses are essential for eliminating SARS-CoV-2, the innate immune system may, in some cases, cause the infection to progress. The cytotoxic CD8+ T cells in adaptive immune responses demonstrated functional exhaustion through upregulation of exhaustion markers. In this regard, humoral immune responses play an essential role in combat SARS-CoV-2 because SARS-CoV-2 restricts antigen presentation through downregulation of MHC class I and II molecules that lead to the inhibition of T cell-mediated immune response responses. This review summarizes the exact pathogenesis of SARS-CoV-2 and the alteration of the immune response during SARS-CoV-2 infection. In addition, we've explained the exhaustion of the immune system during SARS-CoV-2 and the potential immunomodulation approach to overcome this phenomenon. Video Abstract.

The thrombodynamic ratio as a predictor of 28-day mortality in sepsis patients

BACKGROUND

The thrombodynamic ratio (TDR) as a composite thromboelastography (TEG) parameter, has been proven to be valuable in multiple diseases. However, the association between TDR and mortality in sepsis has not been studied.

METHODS

One hundred forty-one patients were enrolled in this retrospectively study. TEG was performed immediately at admission. Two cox proportional hazards models were developed for the prediction of 28-day mortality. The C statistic, continuous net reclassification index (cNRI) and integrated discriminatory index (IDI) were calculated to compare the discrimination performance of clinical models with and without the TDR value. The integrated calibration index (ICI) and E50 were calculated to compare the calibration.

RESULTS

Patients with lower TDR were more likely to have organ impairments and increased 28-day mortality. The TDR value improved discrimination performance in both Model 1 (C statistic, 0.745 vs 0.735; cNRI 19.4%, p =0.044; IDI 5.6%, p =0.012) and Model 2 (C statistic, 0.761 vs 0.751; IDI, 5.1%, p = 0.012). Compared to the calibration curve of Model 1 without TDR, addition of TDR displayed better calibration (ICI, 0.023; E50, 0.021).

CONCLUSION

TDR value significantly predicts 28-day mortality in patients with sepsis and could improve the discrimination and calibration performance of clinical prediction models.

Disseminated intravascular coagulation and its immune mechanisms

Disseminated intravascular coagulation (DIC) is a syndrome triggered by infectious and noninfectious pathologies characterized by excessive generation of thrombin within the vasculature and widespread proteolytic conversion of fibrinogen. Despite diverse clinical manifestations ranging from thrombo-occlusive damage to bleeding diathesis, DIC etiology commonly involves excessive activation of blood coagulation and overlapping dysregulation of anticoagulants and fibrinolysis. Initiation of blood coagulation follows intravascular expression of tissue factor or activation of the contact pathway in response to pathogen-associated or host-derived, damage-associated molecular patterns. The process is further amplified through inflammatory and immunothrombotic mechanisms. Consumption of anticoagulants and disruption of endothelial homeostasis lower the regulatory control and disseminate microvascular thrombosis. Clinical DIC development in patients is associated with worsening morbidities and increased mortality, regardless of the underlying pathology; therefore, timely recognition of DIC is critical for reducing the pathologic burden. Due to the diversity of triggers and pathogenic mechanisms leading to DIC, diagnosis is based on algorithms that quantify hemostatic imbalance, thrombocytopenia, and fibrinogen conversion. Because current diagnosis primarily assesses overt consumptive coagulopathies, there is a critical need for better recognition of nonovert DIC and/or pre-DIC states. Therapeutic strategies for patients with DIC involve resolution of the eliciting triggers and supportive care for the hemostatic imbalance. Despite medical care, mortality in patients with DIC remains high, and new strategies, tailored to the underlying pathologic mechanisms, are needed.

The impact of DAMP-mediated inflammation in severe COVID-19 and related disorders

The host response to SARS-CoV-2, the virus that causes COVID-19, is highly heterogeneous, ranging from mild/asymptomatic to severe. The moderate to severe forms of COVID-19 often require hospitalization, are associated with a high rate of mortality, and appear to be caused by an inappropriately exaggerated inflammatory response to the virus. Emerging data confirm the involvement of both innate and adaptive immune pathways both in protection from SARS-CoV-2, and in driving the pathology of severe COVID-19. In particular, innate immune cells including neutrophils appear to be key players in the inflammation that causes the vicious cycle of damage and inflammation that underlies the symptomatology of severe COVID-19. Several recent studies support a link between damage and inflammation, with damage-associated molecular patterns (DAMPs) playing a key role in the pathology of severe COVID-19. In this review, we put into perspective the role of DAMPs and of components of the DAMP-signaling cascade, including Siglecs and their cognate ligands CD24 and CD52, in COVID-19. Further, we review clinical data on proposed therapeutics targeting DAMP pathways to treat SARS-CoV-2 infection and the regulation of these signaling cascades in COVID-19. We also discuss the potential impact of DAMP-mediated inflammation in other indications related to COVID-19, such as ARDS, endothelial dysfunction, hypercoagulation, and sepsis.

Thromboelastometry in Neonates with Respiratory Distress Syndrome: A Pilot Study

BACKGROUND

Although respiratory distress syndrome (RDS) constitutes a postnatal risk factor for bleeding and thromboembolic events in neonates, few studies have addressed this issue. We aimed to evaluate the hemostatic profile of neonates with RDS using rotational thromboelastometry (ROTEM).

METHODS

An observational study was conducted from November 2018 to November 2020 in the NICU of General Hospital of Nikaia "Aghios Panteleimon". Preterm and term neonates with RDS hospitalized in the NICU were included and EXTEM (tissue factor-triggered extrinsic pathway), INTEM (ellagic acid activated intrinsic pathway), and FIBTEM (with platelet inhibitor cytochalasin D) assays were performed at the onset of the disease.

RESULTS

A hypocoagulable profile was noted in neonates with RDS compared to controls, expressed as significant prolongation of EXTEM CT (clotting time) and CFT (clot formation time), lower EXTEM A10 (amplitude at 10 min), MCF (maximum clot firmness), and LI60 (lysis index). Furthermore, prolongation of INTEM CFT and FIBTEM CT, and decreased INTEM and FIBTEM A10 and MCF were found in neonates with RDS. Multivariable logistic regression analysis showed that RDS is an independent factor for the recorded alterations in ROTEM variables.

CONCLUSIONS

RDS is associated with a hypocoagulable profile and greater hyperfibrinolytic potential compared to healthy neonates.

Azithromycin Reduces Markers of Vascular Damage in Pediatric Patients With Sickle Cell Disease

Background

Immunomodulatory effects of macrolides in chronic inflammation are well known. In this study, we tested our hypothesis that azithromycin (AZT) can decrease inflammation in pediatric patients with sickle cell disease (SCD).

Methods

The use of AZT as an anti-inflammatory agent was evaluated in double-blind, placebo-controlled, cross-over study for 8 weeks of treatment with 8 weeks of washout. Blood samples were collected before (PRE) and after (POST) each 8-week treatment period. Repeated measures analysis of variance (ANOVA) with post hoc multiple comparison procedures and Chi-square test were used for statistical analysis of the data. Complete blood count, distribution of the lymphocyte subsets, and plasma levels of markers of vascular damage were analyzed.

Results

A significant decrease in the number of leucocytes and granulocytes was observed in AZT group following treatment. An opposite dynamic was observed in placebo group; numbers of granulocytes significantly increased at POST interval. All markers of vascular damage were reduced in AZT group at POST interval with overall significance (P = 0.026). The most prominent significant changes were observed in levels of myeloid-related protein 8/14 (MRP8/14), lipocalin A (NGAL), matrix metalloproteinases (MMP) 9, and insulin-like growth factor-binding protein (IGFBP) 4. Plasma level of C-reactive protein (CRP) was significantly decreased in AZT group as well.

Conclusions

Data suggested that AZT may be beneficial in management of microvascular injury in SCD.

COVID-19 and immunothrombosis: emerging understanding and clinical management

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.

Role of DAMPs in respiratory virus-induced acute respiratory distress syndrome-with a preliminary reference to SARS-CoV-2 pneumonia

When surveying the current literature on COVID-19, the "cytokine storm" is considered to be pathogenetically involved in its severe outcomes such as acute respiratory distress syndrome, systemic inflammatory response syndrome, and eventually multiple organ failure. In this review, the similar role of DAMPs is addressed, that is, of those molecules, which operate upstream of the inflammatory pathway by activating those cells, which ultimately release the cytokines. Given the still limited reports on their role in COVID-19, the emerging topic is extended to respiratory viral infections with focus on influenza. At first, a brief introduction is given on the function of various classes of activating DAMPs and counterbalancing suppressing DAMPs (SAMPs) in initiating controlled inflammation-promoting and inflammation-resolving defense responses upon infectious and sterile insults. It is stressed that the excessive emission of DAMPs upon severe injury uncovers their fateful property in triggering dysregulated life-threatening hyperinflammatory responses. Such a scenario may happen when the viral load is too high, for example, in the respiratory tract, "forcing" many virus-infected host cells to decide to commit "suicidal" regulated cell death (e.g., necroptosis, pyroptosis) associated with release of large amounts of DAMPs: an important topic of this review. Ironically, although the aim of this "suicidal" cell death is to save and restore organismal homeostasis, the intrinsic release of excessive amounts of DAMPs leads to those dysregulated hyperinflammatory responses-as typically involved in the pathogenesis of acute respiratory distress syndrome and systemic inflammatory response syndrome in respiratory viral infections. Consequently, as briefly outlined in this review, these molecules can be considered valuable diagnostic and prognostic biomarkers to monitor and evaluate the course of the viral disorder, in particular, to grasp the eventual transition precociously from a controlled defense response as observed in mild/moderate cases to a dysregulated life-threatening hyperinflammatory response as seen, for example, in severe/fatal COVID-19. Moreover, the pathogenetic involvement of these molecules qualifies them as relevant future therapeutic targets to prevent severe/ fatal outcomes. Finally, a theory is presented proposing that the superimposition of coronavirus-induced DAMPs with non-virus-induced DAMPs from other origins such as air pollution or high age may contribute to severe and fatal courses of coronavirus pneumonia.

The Role of DAMPS in Burns and Hemorrhagic Shock Immune Response: Pathophysiology and Clinical Issues. Review

Severe or major burns induce a pathophysiological, immune, and inflammatory response that can persist for a long time and affect morbidity and mortality. Severe burns are followed by a "hypermetabolic response", an inflammatory process that can be extensive and become uncontrolled, leading to a generalized catabolic state and delayed healing. Catabolism causes the upregulation of inflammatory cells and innate immune markers in various organs, which may lead to multiorgan failure and death. Burns activate immune cells and cytokine production regulated by damage-associated molecular patterns (DAMPs). Trauma has similar injury-related immune responses, whereby DAMPs are massively released in musculoskeletal injuries and elicit widespread systemic inflammation. Hemorrhagic shock is the main cause of death in trauma. It is hypovolemic, and the consequence of volume loss and the speed of blood loss manifest immediately after injury. In burns, the shock becomes evident within the first 24 h and is hypovolemic-distributive due to the severely compromised regulation of tissue perfusion and oxygen delivery caused by capillary leakage, whereby fluids shift from the intravascular to the interstitial space. In this review, we compare the pathophysiological responses to burns and trauma including their associated clinical patterns.

Strategies to DAMPen COVID-19-mediated lung and systemic inflammation and vascular injury

Approximately 15%-20% of patients infected with SARS-CoV-2 coronavirus (COVID-19) progress beyond mild and self-limited disease to require supplemental oxygen for severe pneumonia; 5% of COVID-19-infected patients further develop acute respiratory distress syndrome (ARDS) and multiorgan failure. Despite mortality rates surpassing 40%, key insights into COVID-19-induced ARDS pathology have not been fully elucidated and multiple unmet needs remain. This review focuses on the unmet need for effective therapies that target unchecked innate immunity-driven inflammation which drives unchecked vascular permeability, multiorgan dysfunction and ARDS mortality. Additional unmet needs including the lack of insights into factors predicting pathogenic hyperinflammatory viral host responses, limited approaches to address the vast disease heterogeneity in ARDS, and the absence of clinically-useful ARDS biomarkers. We review unmet needs persisting in COVID-19-induced ARDS in the context of the potential role for damage-associated molecular pattern proteins in lung and systemic hyperinflammatory host responses to SARS-CoV-2 infection that ultimately drive multiorgan dysfunction and ARDS mortality. Insights into promising stratification-enhancing, biomarker-based strategies in COVID-19 and non-COVID ARDS may enable the design of successful clinical trials of promising therapies.

Effects of Thrombomodulin in Reducing Lethality and Suppressing Neutrophil Extracellular Trap Formation in the Lungs and Liver in a Lipopolysaccharide-Induced Murine Septic Shock Model

Neutrophil extracellular trap (NET) formation, an innate immune system response, is associated with thrombogenesis and vascular endothelial injury. Circulatory disorders due to microvascular thrombogenesis are one of the principal causes of organ damage. NET formation in organs contributes to the exacerbation of sepsis, which is defined as a life-threatening organ dysfunction caused by a dysregulated host response to infection. We have previously reported that recombinant human soluble thrombomodulin (rTM) reduces lipopolysaccharide (LPS)-induced NET formation in vitro. Here, we aimed to show that thrombomodulin (TM)-mediated suppression of NET formation protects against organ damage in sepsis. Mice were injected intraperitoneally (i.p.) with 10 mg/kg LPS. rTM (6 mg/kg/day) or saline was administered i.p. 1 h after LPS injection. In the LPS-induced murine septic shock model, extracellular histones, which are components of NETs, were observed in the liver and lungs. In addition, the serum cytokine (interleukin-1β (IL-1β), interleukin-6 (IL-6), tumor necrosis factor-α (TNF-α), macrophage chemotactic protein-1 (MCP-1), and interleukin-10 (IL-10)) levels were increased. The administration of rTM in this model prevented NET formation in the organs and suppressed the increase in the levels of all cytokines except IL-1β. Furthermore, the survival rate improved. We provide a novel role of TM in treating inflammation and NETs in organs during sepsis.

Endotheliopathy in septic conditions: mechanistic insight into intravascular coagulation

Endothelial cells play a key role in maintaining intravascular patency through their anticoagulant properties. They provide a favorable environment for plasma anticoagulant proteins, including antithrombin, tissue factor pathway inhibitor, and protein C. Under septic conditions, however, the anticoagulant properties of endothelial cells are compromised. Rather, activated/injured endothelial cells can provide a scaffold for intravascular coagulation. For example, the expression of tissue factor, an important initiator of the coagulation pathway, is induced on the surface of activated endothelial cells. Phosphatidylserine, a high-affinity scaffold for gamma-carboxyglutamate domain containing coagulation factors, including FII, FVII, FIX, and FX, is externalized to the outer leaflet of the plasma membrane of injured endothelial cells. Hemodilution decreases not only coagulation factors but also plasma anticoagulant proteins, resulting in unleashed activation of coagulation on the surface of activated/injured endothelial cells. The aberrant activation of coagulation can be suppressed in part by the supplementation of recombinant antithrombin and recombinant thrombomodulin. This review aims to overview the physiological and pathological functions of endothelial cells along with proof-of-concept in vitro studies. The pathophysiology of COVID-19-associated thrombosis is also discussed.

The Role of Histones and Heparin in Sepsis: A Review

Septic shock with multiple organ failure is a devastating situation in clinical settings. Through the past decades, much progress has been made in the management of sepsis and its underlying pathogenesis, but a highly effective therapeutic has not been developed. Recently, macromolecules such as histones have been targeted in the treatment of sepsis. Histones primarily function as chromosomal organizers to pack DNA and regulate its transcription through epigenetic mechanisms. However, a growing body of research has shown that histone family members can also exert cellular toxicity once they relocate from the nucleus into the extracellular space. Heparin, a commonly used anti-coagulant, has been shown to possess life-saving capabilities for septic patients, but the potential interplay between heparin and extracellular histones has not been investigated. In this review, we summarize the pathogenic roles of extracellular histones and the therapeutic roles of heparin in the development and management of sepsis and septic shock.

Systemic Coagulopathy in Hospitalized Patients With Coronavirus Disease 2019: A Systematic Review and Meta-Analysis

Coagulation activation has been reported in several cohorts of patients Coronavirus Disease 2019 (COVID-19). However, the true burden of systemic coagulopathy in COVID-19 remains unknown. In this systematic review and meta-analysis, we performed a literature search using PubMed, EMBASE, and Cochrane Database to identify studies that reported the prevalence of systemic coagulopathy using established criteria in patients with COVID-19. The primary outcome was the prevalence of systemic coagulopathy (disseminated intravascular coagulation [DIC] and/or sepsis-induced coagulopathy [SIC]). Pooled prevalences and 95% confidence intervals [CIs] were calculated using random-effects model. A total of 5 studies including 1210 patients with confirmed COVID-19 were included. The pooled prevalence of systemic coagulopathy was 7.1% (95%CI: 3.2%,15.3%, I² = 93%). The pooled prevalence of DIC (N = 721) and SIC (N = 639) were 4.3% (95%CI 1.7%, 10.4%, I² = 84%) and 16.2% (95%CI: 9.3%, 26.8%, I² = 74%), respectively. Only 2 studies reported the prevalence of elevated D-dimer levels with the pooled prevalence of 84.6% (95%CI: 52.0%,96.5%, I² = 94%). Average D-dimer and fibrinogen levels were remarkably increased, while platelet counts, PT, and aPTT ratios were minimally affected in COVID-19. The estimated prevalence of systemic coagulopathy in patients with COVID-19 was low despite D-dimer elevation in most patients. Relatively low systemic coagulopathy in COVID-19 may contribute to the high incidence of thrombosis rather than bleeding in patients with COVID-19.

Association between plasma complement factor H concentration and clinical outcomes in patients with sepsis

Aim

The complement system is important for defending against pathogens, however, excessive complement activation is associated with a poor prognosis and organ dysfunction in sepsis. Complement factor H (CFH) acts to prevent excessive complement activation and damage to the self through the regulation of the complement alternative pathway. We investigated the association between plasma CFH levels on admission to the intensive care unit (ICU) and 90‐day mortality, severity scores, and organ dysfunction in patients with sepsis.

Methods

We assessed the relationship between the plasma CFH on admission to the ICU and 90‐day mortality, severity scores such as the Acute Physiology and Chronic Health Evaluation II score, Sequential Organ Failure Assessment score, and Simplified Acute Physiology Score 2, and organ dysfunction.

Results

This analysis included 62 patients. The plasma CFH levels were significantly lower in 90‐day non‐survivors than in survivors (70.0 μg/mL [interquartile range, 51.2–97.6] versus 104.8 μg/mL [interquartile range, 66.8–124.2]; P = 0.006) . The plasma CFH levels were associated with 90‐day mortality (odds ratio 0.977; 95% confidence interval, 0.957–0.994; P = 0.01). The plasma CFH levels were negatively correlated with severity scores. The Sequential Organ Failure Assessment scores for the coagulation and neurological components were negatively correlated with the CFH concentration.

Conclusion

Lower plasma levels of CFH were associated with increased severity and mortality in patients with sepsis on admission to the ICU and were correlated with central nervous system dysfunction and coagulopathy.

Preventing the development of severe COVID-19 by modifying immunothrombosis

BACKGROUND

COVID-19-associated acute respiratory distress syndrome (ARDS) is associated with significant morbidity and high levels of mortality. This paper describes the processes involved in the pathophysiology of COVID-19 from the initial infection and subsequent destruction of type II alveolar epithelial cells by SARS-CoV-2 and culminating in the development of ARDS.

MAIN BODY

The activation of alveolar cells and alveolar macrophages leads to the release of large quantities of proinflammatory cytokines and chemokines and their translocation into the pulmonary vasculature. The presence of these inflammatory mediators in the vascular compartment leads to the activation of vascular endothelial cells platelets and neutrophils and the subsequent formation of platelet neutrophil complexes. These complexes in concert with activated endothelial cells interact to create a state of immunothrombosis. The consequence of immunothrombosis include hypercoagulation, accelerating inflammation, fibrin deposition, migration of neutrophil extracellular traps (NETs) producing neutrophils into the alveolar apace, activation of the NLRP3 inflammazome, increased alveolar macrophage destruction and massive tissue damage by pyroptosis and necroptosis Therapeutic combinations aimed at ameliorating immunothrombosis and preventing the development of severe COVID-19 are discussed in detail.

Endothelial Responses in Sepsis

Endothelial cells (ECs) are vascular, nonconventional immune cells that play a major role in the systemic response after bacterial infection to limit its dissemination. Triggered by exposure to pathogens, microbial toxins, or endogenous danger signals, EC responses are polymorphous, heterogeneous, and multifaceted. During sepsis, ECs shift toward a proapoptotic, proinflammatory, proadhesive, and procoagulant phenotype. In addition, glycocalyx damage and vascular tone dysfunction impair microcirculatory blood flow, leading to organ injury and, potentially, life-threatening organ failure. This review aims to cover the current understanding of the EC adaptive or maladaptive response to acute inflammation or bacterial infection based on compelling recent basic research and therapeutic clinical trials targeting microvascular and endothelial alterations during septic shock.

COVID-19 and Major Organ Thromboembolism: Manifestations in Neurovascular and Cardiovascular Systems

COVID-19, caused by the severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2), has been shown to cause multisystemic damage. We undertook a systematic literature review and comprehensive analysis of a total of 55 articles on arterial and venous thromboembolism in COVID-19 and articles on previous pandemics with respect to thromboembolism and compared the similarities and differences between them. The presence of thrombosis in multiple organ systems points to thromboembolism being an integral component in the pathogenesis of this disease. Thromboembolism is likely to be the main player in the morbidity and mortality of COVID -19 in which the pulmonary system is most severely affected. We also hypothesize that D-dimer values could be used as an early marker for prognostication of disease as it has been seen to be raised even in the pre-symptomatic stage. This further strengthens the notion that thromboembolism prevention is necessary. We also examined literature on the neurovascular and cardiovascular systems, as the manifestation of thromboembolic phenomenon in these two systems varied, suggesting different pathophysiology of damage. Further research into the role of thromboembolism in COVID-19 is important to advance the understanding of the virus, its effects and to tailor treatment accordingly to prevent further casualties from this pandemic.

Recombinant thrombomodulin alleviates oxidative stress without compromising host resistance to infection in rats infected with methicillin-resistant Staphylococcus aureus

Recombinant thrombomodulin (rTM) has been used for treatment of sepsis-associated disseminated intravascular coagulation. Recent studies have suggested that anticoagulant therapy might dampen the protective role of immunothrombosis. We examined if rTM might worsen infectious diseases. Male Sprague-Dawley rats with jugular-vein catheterization were divided into three groups: no anticoagulation; rTM pretreatment; rTM treatment at 6 h. Live methicillin-resistant Staphylococcus aureus (MRSA) was inoculated into the tail vein of rats. rTM was administered into the jugular-vein catheter before or 6 h after MRSA inoculation, while an equal volume of saline was administered in the no-anticoagulation group. Blood samples were collected from the jugular-vein catheter before, 6 h and 12 h after MRSA inoculation. Tissue samples were collected from anesthetized rats when moribund or 18 h after MRSA inoculation. The survival rate of rats in the no-anticoagulation group, rTM pretreatment group, and rTM treatment at 6-h group was 50%, 25%, and 75%, respectively. Bacterial burden in blood, lung, liver, and spleen was neither increased nor decreased in rats treated with rTM. The ratio of bacteria found in the extravascular space to those in the intravascular space was increased in rats treated with rTM although the statistical power for this was low because of the small sample size. Metabolomics analysis revealed that rTM treatment alleviated oxidative stress, as evidenced by the decrease in levels of oxidized glutathione with reference to reduced glutathione. rTM did not promote bacterial propagation but alleviated oxidative stress in our rat model of bloodstream infection with MRSA. Further large-scale studies are needed to confirm these findings.

Effects of thrombomodulin alfa on hemostatic parameters in disseminated intravascular coagulation: Post hoc analysis of a phase 3 randomized controlled trial

BACKGROUND

The efficacy and safety of thrombomodulin alfa (TM-α), a cofactor protein promoting thrombin-mediated protein C activation, have been examined in a phase 3 randomized, double-blinded, parallel-group trial in Japan. We have previously reported that TM-α is noninferior to heparin for the resolution of disseminated intravascular coagulation (DIC).

OBJECTIVE

To investigate the basis for the efficacy of TM-α in the phase 3 clinical trial in Japan through post hoc analysis of coagulation and fibrinolysis parameters.

PATIENTS/METHODS

The 227 patients of the full analysis set population described in the original phase 3 trial in Japan were included in this analysis. Changes in parameters between before and after TM-α or heparin administration in each of the two patient groups, with underlying diseases of either hematologic malignancy or infection, were studied separately and results were compared between TM-α and heparin treatment groups in a post hoc manner.

RESULTS

TM-α administration did not prolong activated partial thromboplastin time but significantly decreased thrombin-antithrombin complex levels compared with heparin treatment. TM-α administration reduced consumption of endogenous anticoagulants such as antithrombin and protein C by DIC, compared with the heparin group. DIC scores were decreased in both TM-α and heparin groups during the 6-day treatment.

CONCLUSION

TM-α can alleviate intravascular coagulation and consumption of anticoagulants without extending coagulation times. This may be associated with the relatively low risk of bleeding during TM-α treatment.

The pathophysiology of SARS-CoV-2: A suggested model and therapeutic approach

In this paper, a model is proposed of the pathophysiological processes of COVID-19 starting from the infection of human type II alveolar epithelial cells (pneumocytes) by SARS-CoV-2 and culminating in the development of ARDS. The innate immune response to infection of type II alveolar epithelial cells leads both to their death by apoptosis and pyroptosis and to alveolar macrophage activation. Activated macrophages secrete proinflammatory cytokines and chemokines and tend to polarise into the inflammatory M1 phenotype. These changes are associated with activation of vascular endothelial cells and thence the recruitment of highly toxic neutrophils and inflammatory activated platelets into the alveolar space. Activated vascular endothelial cells become a source of proinflammatory cytokines and reactive oxygen species (ROS) and contribute to the development of coagulopathy, systemic sepsis, a cytokine storm and ARDS. Pulmonary activated platelets are also an important source of proinflammatory cytokines and ROS, as well as exacerbating pulmonary neutrophil-mediated inflammatory responses and contributing to systemic sepsis by binding to neutrophils to form platelet-neutrophil complexes (PNCs). PNC formation increases neutrophil recruitment, activation priming and extraversion of these immune cells into inflamed pulmonary tissue, thereby contributing to ARDS. Sequestered PNCs cause the development of a procoagulant and proinflammatory environment. The contribution to ARDS of increased extracellular histone levels, circulating mitochondrial DNA, the chromatin protein HMGB1, decreased neutrophil apoptosis, impaired macrophage efferocytosis, the cytokine storm, the toll-like receptor radical cycle, pyroptosis, necroinflammation, lymphopenia and a high Th17 to regulatory T lymphocyte ratio are detailed.

Immunology of COVID-19: Mechanisms, clinical outcome, diagnostics, and perspectives-A report of the European Academy of Allergy and Clinical Immunology (EAACI)

With the worldwide spread of the novel severe acute respiratory syndrome coronavirus‐2 (SARS‐CoV‐2) resulting in declaration of a pandemic by the World Health Organization (WHO) on March 11, 2020, the SARS‐CoV‐2‐induced coronavirus disease‐19 (COVID‐19) has become one of the main challenges of our times. The high infection rate and the severe disease course led to major safety and social restriction measures worldwide. There is an urgent need of unbiased expert knowledge guiding the development of efficient treatment and prevention strategies. This report summarizes current immunological data on mechanisms associated with the SARS‐CoV‐2 infection and COVID‐19 development and progression to the most severe forms. We characterize the differences between adequate innate and adaptive immune response in mild disease and the deep immune dysfunction in the severe multiorgan disease. The similarities of the human immune response to SARS‐CoV‐2 and the SARS‐CoV and MERS‐CoV are underlined. We also summarize known and potential SARS‐CoV‐2 receptors on epithelial barriers, immune cells, endothelium and clinically involved organs such as lung, gut, kidney, cardiovascular, and neuronal system. Finally, we discuss the known and potential mechanisms underlying the involvement of comorbidities, gender, and age in development of COVID‐19. Consequently, we highlight the knowledge gaps and urgent research requirements to provide a quick roadmap for ongoing and needed COVID‐19 studies.

The Potential Role of Heparin in Patients With COVID-19: Beyond the Anticoagulant Effect. A Review

Severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) infection is responsible of variable clinical manifestations, ranging from no symptoms to severe pneumonia with acute respiratory distress syndrome, septic shock, and multi-organ failure resulting in death. To date no specific antiviral drug have been approved for COVID-19, so the treatment of the disease is mainly focused on symptomatic treatment and supportive care. Moreover, there are no treatments of proven efficacy to reduce the progression of the disease from mild/moderate to severe/critical. An activation of the coagulation cascade leading to severe hypercoagulability has been detected in these patients, therefore early anticoagulation may reduce coagulopathy, microthrombus formation, and the risk of organ damages. The role of heparin in COVID-19 is supported by a lot of studies describing its pleiotropic activity but it must be proven in clinical trials. Several protocols have been designed to assess the risk-benefit profile of heparin (low-molecular-weight or unfractionated heparin) in hospitalized subjects. Although prophylactic doses may be adequate in most patients, it is important to wait the results of clinical trials in order to define the appropriate effective dose able to improve disease outcome.

COVID-19-Associated Coagulopathy: An Exacerbated Immunothrombosis Response

Since the onset of the global pandemic in early 2020, coronavirus disease 2019 (COVID-19) has posed a multitude of challenges to health care systems worldwide. In order to combat these challenges and devise appropriate therapeutic strategies, it becomes of paramount importance to elucidate the pathophysiology of this illness. Coronavirus disease 2019, caused by the novel severe acute respiratory syndrome coronavirus 2 (SARS-CoV2), is characterized by a dysregulated immune system and hypercoagulability. COVID-associated coagulopathy (CAC) was recognized based on profound d-dimer elevations and evidence of microthrombi and macrothrombi, both in venous and arterial systems. The underlying mechanisms associated with CAC have been suggested, but not clearly defined. The model of immunothrombosis illustrates the elaborate crosstalk between the innate immune system and coagulation. The rendering of a procoagulant state in COVID-19 involves the interplay of many innate immune pathways. The SARS-CoV2 virus can directly infect immune and endothelial cells, leading to endothelial injury and dysregulation of the immune system. Activated leukocytes potentiate a procoagulant state via release of intravascular tissue factor, platelet activation, NETosis, and inhibition of anticoagulant mechanisms. Additional pathways of specific relevance in CAC include cytokine release and complement activation. All these mechanisms have recently been reported in COVID-19. Immunothrombosis provides a comprehensive perspective of the several synergistic pathways pertinent to the pathogenesis of CAC.

Damage-associated molecular patterns in trauma

In 1994, the "danger model" argued that adaptive immune responses are driven rather by molecules released upon tissue damage than by the recognition of "strange" molecules. Thus, an alternative to the "self versus non-self recognition model" has been provided. The model, which suggests that the immune system discriminates dangerous from safe molecules, has established the basis for the future designation of damage-associated molecular patterns (DAMPs), a term that was coined by Walter G. Land, Seong, and Matzinger. The pathological importance of DAMPs is barely somewhere else evident as in the posttraumatic or post-surgical inflammation and regeneration. Since DAMPs have been identified to trigger specific immune responses and inflammation, which is not necessarily detrimental but also regenerative, it still remains difficult to describe their "friend or foe" role in the posttraumatic immunogenicity and healing process. DAMPs can be used as biomarkers to indicate and/or to monitor a disease or injury severity, but they also may serve as clinically applicable parameters for optimized indication of the timing for, i.e., secondary surgeries. While experimental studies allow the detection of these biomarkers on different levels including cellular, tissue, and circulatory milieu, this is not always easily transferable to the human situation. Thus, in this review, we focus on the recent literature dealing with the pathophysiological importance of DAMPs after traumatic injury. Since dysregulated inflammation in traumatized patients always implies disturbed resolution of inflammation, so-called model of suppressing/inhibiting inducible DAMPs (SAMPs) will be very briefly introduced. Thus, an update on this topic in the field of trauma will be provided.