Animal models of DIC and their relevance to human DIC: a systematic review

Sepsis induces heterogeneous transcription of coagulation- and inflammation-associated genes in renal microvasculature

BACKGROUND

Acute kidney injury (AKI) in sepsis patients increases patient mortality. Endothelial cells are important players in the pathophysiology of sepsis-associated AKI (SA-AKI), yet knowledge regarding their spatiotemporal involvement in coagulation disbalance and leukocyte recruitment is lacking. This study investigated the identity and kinetics of responses of different microvascular compartments in kidney cortex in response to SA-AKI.

METHODS

Laser microdissected arterioles, glomeruli, peritubular capillaries, and postcapillary venules from kidneys of mice subjected to cecal ligation and puncture (CLP) were analyzed using RNA sequencing. Differential expression and pathway enrichment analyses identified genes involved in coagulation and inflammation. A selection of these genes was evaluated by RT-qPCR in microvascular compartments of renal biopsies from patients with SA-AKI. The role of two identified genes in lipopolysaccharide-induced endothelial coagulation and inflammatory activation were determined in vitro in HUVEC using siRNA-based gene silencing.

RESULTS

CLP-sepsis in mice induced altered expression of approximately 400 genes in the renal microvasculature, with microvascular compartments exhibiting unique spatiotemporal responses. In mice, changes in gene expression related to coagulation and inflammation were most extensive in glomeruli at early and intermediate time points, with high induction of Plat, Serpine1, Thbd, Icam1, Stat3, and Ifitm3. In human SA-AKI, PROCR and STAT3 were induced in postcapillary venules, while SERPINE1 expression was diminished. IFITM3 was increased in arterioles and glomeruli. In vitro studies revealed that STAT3 and IFITM3 partly control endothelial coagulation and inflammatory activation.

CONCLUSION

Renal microvascular compartments in mice and humans exhibited heterogeneous changes in coagulation- and inflammation-related gene expression in response to SA-AKI. Additional research should aim at understanding the functional consequences of the here described heterogeneous microvascular responses to establish the usefulness of identified genes as therapeutic targets in SA-AKI.

Coagulation Disorders, Testing, and Treatment in Exotic Animal Critical Care

Despite poor recognition in the literature, exotic companion animals are affected by many diseases that can result in disordered coagulation and fibrinolysis. This article outlines current knowledge of hemostasis, common diagnostic tests and reviews reported diseases associated with coagulopathy in small mammals, bird and reptiles. A range of conditions affect platelets and thrombocytes, endothelium and blood vessels, and plasma clotting factors. Improved recognition and monitoring of hemostatic disorders will enable targeted therapy and improved case outcomes.

The coming of age of neutrophil extracellular traps in thrombosis: Where are we now and where are we headed?

Thrombosis remains a major problem in our society, manifesting across multiple demographic groups and with high associated morbidity and mortality. Thrombus development is the result of a complex mechanism in which multiple cell types and soluble factors play a crucial role. One cell that has gained the most attention in recent years is the neutrophil. This key member of the innate immune system can form neutrophil extracellular traps (NETs) in response to activating stimuli in circulation. NETs form a scaffold for thrombus formation, both initiating the process and stabilizing the final product. As the first responders of the host immune system, neutrophils have the flexibility to recognize a variety of molecules and can quickly interact with a range of different cell types. This trait makes them sensitive to exogenous stimuli. NET formation in response to pathogens is well established, leading to immune-mediated thrombus formation or immunothrombosis. NETs can also be formed during sterile inflammation through the activation of neutrophils by fellow immune cells including platelets, or activated endothelium. In chronic inflammatory settings, NETs can ultimately promote the development of tissue fibrosis, with organ failure as an end-stage outcome. In this review, we discuss the different pathways through which neutrophils can be activated toward NET formation and how these processes can result in a shared outcome: thrombus formation. Finally, we evaluate these different interactions and mechanisms for their potential as therapeutic targets, with neutrophil-targeted therapies providing a future approach to treating thrombosis. In contrast to current practices, such treatment could result in reduced pathogenic blood clot formation without increasing the risk of bleeding.

Disseminated Intravascular Coagulation (DIC): Old player creates new perspectives on the polymicrobial sepsis model of CASP

BACKGROUND

Disseminated Intravascular Coagulation (DIC) is a life-threatening complication of sepsis. In surgical ICUs, DIC is frequently caused by abdominal sepsis, and the disarranged coagulation and complications often lead to death. The severity of sepsis is associated with a higher DIC score according to the parameters proposed by the International Society of Hemostasis and Thrombosis (ISTH) in 2001: platelet count, bleeding time (Quick), D-dimer, and fibrinogen. One problem in studying DIC is finding an adequate animal model that reflects the clinical situation of polymicrobial overwhelming infection.

AIMS AND METHODS

We investigated whether a well-established polymicrobial sepsis model of colon ascendens stent peritonitis (CASP) is suited to investigate the complexity of DIC. For this purpose, CASP-operated mice were examined 20 h after the operation with regard to coagulation parameters using cell counts, bleeding times, rotational thromboelastometry (ROTEM), ELISAs for D-dimer and fibrinogen, and platelet accumulation in affected organs via immunohistochemistry to see if the mice develop a coagulation disorder that meets the definition of DIC proposed by the ISTH 2001 consensus conference.

RESULTS

Herein, we showed that the CASP model is an all-encompassing animal model to analyze the complexity of systemic DIC in murine abdominal sepsis. There is highly reproducible thrombocytopenia, a significant prolongation of the bleeding time, and a loss of fibrinogen in plasma. We also observed microvascular thrombosis due to platelet accumulation in the microcirculation of the liver.

CONCLUSION

The CASP model seems superior to other artificial models, e.g., injecting substances, for inducing DIC. CASP is one of the best true-to-life models for analyzing the complexity of disseminated intravascular coagulation in polymicrobial sepsis.

LCZ696 protects against doxorubicin-induced cardiotoxicity by inhibiting ferroptosis via AKT/SIRT3/SOD2 signaling pathway activation

Doxorubicin (DOX) is an effective and widely used anticancer drug but has limited clinical applicability because of its cardiotoxicity. Ferroptosis plays a key role in DOX-induced cardiac damage and cardiomyocyte cell death. The inhibition of ferroptosis reverses DOX-induced cardiotoxicity (DIC). LCZ696, a first-in-class angiotensin receptor neprilysin inhibitor, protects against DIC. However, the mechanism of action of LCZ696, especially its effect on ferroptosis, is incompletely understood. This study investigates the cardioprotective effects of LCZ696 on DIC in vivo and in vitro.Cardiotoxicity was induced in Wistar rats by tail intravenous injection of 2.5 mg/kg DOX once a week for six weeks. Rats and H9c2 cells were treated with or without LCZ696 to determine the cardioprotective role and underlying mechanisms of LCZ696 against DIC. To assess the role of SIRT3 and correlated pathways in ferroptosis, SIRT3 knockout was performed using lentiviral vectors, and AKT was inhibited with LY294002. LCZ696 significantly attenuated DIC by decreasing the concentrations of lipid reactive oxygen species and malondialdehyde and increasing the levels of glutathione peroxidase-4 and reduced glutathione in cells and heart tissues. Moreover, LCZ696 remodeled myocardial structures and improved heart ventricular function in DOX-treated rats. LCZ696 treatment increased SIRT3 expression and deacetylated its target gene SOD2, and these changes were mediated by AKT activation. SIRT3 knockdown and AKT inhibition induced lipid peroxidation and reduced the protective effect of LCZ696 in H9c2 cells. Collectively,LCZ696 prevents DIC by inhibiting ferroptosis via AKT/SIRT3/SOD2 signaling pathway activation. Thus, LZC696 is a potential therapeutic strategy for DIC.

Salvianolic acid A alleviates lipopolysaccharide-induced disseminated intravascular coagulation by inhibiting complement activation

Introduction

Disseminated intravascular coagulation (DIC) is a syndrome characterized by coagulopathy, microthrombus, and multiple organ failure. The complement system in DIC is overactivated, and the functions of complement and coagulation pathways are closely related. Our previous screening revealed that salvianolic acid A (SAA) has anti-complement activity. The hyper-activated complement system was involved in the lipopolysaccharide (LPS) induced DIC in rats. The effects of SAA anti-complement action on LPS-induced DIC in rats were investigated.

Methods

The complement activity of the classical pathway and alternative pathway was detected through an in vitro hemolysis assay. The binding sites of SAA and complement C3b were predicted by molecular docking. LPS-induced disseminated coagulation experiments were performed on male Wistar rats to assess coagulation function, complement activity, inflammation, biochemistry, blood routine, fibrinolysis, and survival.

Results

SAA had an anti-complement activity in vivo and in vitro and inhibited the complement activation in the classical and alternative pathway of complement. The infusion of LPS into the rats impaired the coagulation function, increased the plasma inflammatory cytokine level, complemented activation, reduced the clotting factor levels, fibrinogen, and platelets, damaged renal, liver, and lung functions, and led to a high mortality rate (85%). SAA treatment of rats inhibited complement activation and attenuated the significant increase in D-dimer, interleukin-6, alanine aminotransferase, and creatinine. It ameliorated the decrease in plasma levels of fibrinogen and platelets and reversed the decline in activity of protein C and antithrombin III. The treatment reduced kidney, liver, and lung damage, and significantly improved the survival rate of rats (46.2 and 78.6% for the low- and high-dose groups, respectively).

Conclusion

SAA reduced LPS-induced DIC by inhibiting complement activation. It has considerable potential in DIC treatment.

Unlocking the Untapped Potential of Endothelial Kinase and Phosphatase Involvement in Sepsis for Drug Treatment Design

Sepsis is a devastating clinical condition that can lead to multiple organ failure and death. Despite advancements in our understanding of molecular mechanisms underlying sepsis and sepsis-associated multiple organ failure, no effective therapeutic treatment to directly counteract it has yet been established. The endothelium is considered to play an important role in sepsis. This review highlights a number of signal transduction pathways involved in endothelial inflammatory activation and dysregulated endothelial barrier function in response to sepsis conditions. Within these pathways – NF-κB, Rac1/RhoA GTPases, AP-1, APC/S1P, Angpt/Tie2, and VEGF/VEGFR2 – we focus on the role of kinases and phosphatases as potential druggable targets for therapeutic intervention. Animal studies and clinical trials that have been conducted for this purpose are discussed, highlighting reasons why they might not have resulted in the expected outcomes, and which lessons can be learned from this. Lastly, opportunities and challenges that sepsis and sepsis-associated multiple organ failure research are currently facing are presented, including recommendations on improved experimental design to increase the translational power of preclinical research to the clinic.

Ultramicronized Palmitoylethanolamide in the Management of Sepsis-Induced Coagulopathy and Disseminated Intravascular Coagulation

Disseminated intravascular coagulation (DIC) is a severe condition characterized by the systemic formation of microthrombi complicated with bleeding tendency and organ dysfunction. In the last years, it represents one of the most frequent consequences of coronavirus disease 2019 (COVID-19). The pathogenesis of DIC is complex, with cross-talk between the coagulant and inflammatory pathways. The objective of this study is to investigate the anti-inflammatory action of ultramicronized palmitoylethanolamide (um-PEA) in a lipopolysaccharide (LPS)-induced DIC model in rats. Experimental DIC was induced by continual infusion of LPS (30 mg/kg) for 4 h through the tail vein. Um-PEA (30 mg/kg) was given orally 30 min before and 1 h after the start of intravenous infusion of LPS. Results showed that um-PEA reduced alteration of coagulation markers, as well as proinflammatory cytokine release in plasma and lung samples, induced by LPS infusion. Furthermore, um-PEA also has the effect of preventing the formation of fibrin deposition and lung damage. Moreover, um-PEA was able to reduce the number of mast cells (MCs) and the release of its serine proteases, which are also necessary for SARS-CoV-2 infection. These results suggest that um-PEA could be considered as a potential therapeutic approach in the management of DIC and in clinical implications associated to coagulopathy and lung dysfunction, such as COVID-19.

Attempt to Develop Rat Disseminated Intravascular Coagulation Model Using Yamakagashi (Rhabdophis tigrinus) Venom Injection

Disseminated intravascular coagulation, a severe clinical condition caused by an underlying disease, involves a markedly continuous and widespread activation of coagulation in the circulating blood and the formation of numerous microvascular thrombi. A snakebite, including that of the Yamakagashi (Rhabdophis tigrinus), demonstrates this clinical condition. Thus, an animal model using Yamakagashi venom was constructed. Yamakagashi venom was administered to rats, and its lethality and the changes in blood coagulation factors were detected after venom injection. When 300 μg venom was intramuscularly administered to 12-week-old rats, (1) they exhibited hematuria with plasma hemolysis and died within 48 h; (2) Thrombocytopenia in the blood was observed in the rats; (3) irreversible prolongation of prothrombin time in the plasma to the measurement limit occurred; (4) fibrinogen concentration in the plasma irreversibly decreased below the measurement limit; and (5) A transient increase in the plasma concentration of D-dimer was observed. In this model, a fixed amount of Rhabdophis tigrinus venom injection resulted in the clinical symptom similar to the human pathology with snakebite. The use of the rat model is very effective in validating the therapeutic effect of human disseminated intravascular coagulation condition due to snakebite.

The swine as a vehicle for research in trauma-induced coagulopathy: Introducing principal component analysis for viscoelastic coagulation tests

BACKGROUND

Uncontrolled bleeding is the leading cause of potentially preventable deaths among trauma patients. Tissue injury and shock result in trauma-induced coagulopathy (TIC). There are still uncertainties regarding detection methods and best practice management for TIC, and a deeper understanding of the pathophysiology requires robust animal models. The applicability of swine in coagulation studies, particularly after trauma has not been sufficiently elucidated. We, therefore, evaluated the swine as a vehicle for TIC research in a selection of trauma modalities.

METHODS

Twenty-six landrace swine (3 females/23 males) (mean weight, 60.0 kg) were anesthetized and randomized to negative controls, receiving no manipulation (n = 5), positive controls by hemodilution (n = 5), pulmonary contusion without hemorrhage (n = 5), pulmonary contusion with hemorrhage (n = 5), and blast polytrauma with hypothermia, hypoperfusion, hypoventilation, and systemic inflammation (n = 6). A comprehensive coagulation panel was analyzed at baseline, 20 minutes and 120 minutes after trauma.

RESULTS

PT(INR), aPTT, thrombocytes, and fibrinogen did not change after trauma. D-dimer increased (p < 0.0001), prothrombin decreased (p < 0.05) and aPC decreased (p < 0.01) after polytrauma. PAI-1 decreased after pulmonary contusion with hemorrhage (p < 0.05). Positive controls displayed changes in PT(INR), thrombocytes, fibrinogen, prothrombin, aPC (p < 0.05). Principal Component Analysis of rotational thromboelastometry presented pathologic coagulation profiles in both polytrauma and positive control groups with vectors extending outside the 95% confidence interval, which were not detected in negative controls.

CONCLUSION

Coagulopathy was induced after severe porcine blast polytrauma, specifically detected in rotational thromboelastometry. A novel method for principal component analysis of viscoelastic tests was introduced which may increase the detection sensitivity and differentiation of TIC phenotypes and should be further investigated in trauma populations.

Consumptive coagulopathy of severe yellow fever occurs independently of hepatocellular tropism and massive hepatic injury

Fatal cases of yellow fever are preceded by the development of hemorrhagic complications. While yellow fever virus is known to infect hepatocytes, the relationship between hepatocyte infection and the development of hemorrhage is currently undefined. Here, we identified high concentrations of D-dimer in the blood of yellow fever patients, indicative of a process that involves the activation and consumption of clotting factors. We then developed a mouse model in which only transplanted human hepatocytes could be infected at high levels. By examining clotting parameters in this model, we determined that hepatocyte infection alone is insufficient to cause the activation and consumption of coagulation factors observed in severe cases of yellow fever in humans and nonhuman primates.

Yellow fever (YF) is a mosquito-transmitted viral disease that causes tens of thousands of deaths each year despite the long-standing deployment of an effective vaccine. In its most severe form, YF manifests as a hemorrhagic fever that causes severe damage to visceral organs. Although coagulopathy is a defining feature of severe YF in humans, the mechanism by which it develops remains uncertain. Hepatocytes are a major target of yellow fever virus (YFV) infection, and the coagulopathy in severe YF has long been attributed to massive hepatocyte infection and destruction that results in a defect in clotting factor synthesis. However, when we analyzed blood from Brazilian patients with severe YF, we found high concentrations of plasma D-dimer, a fibrin split product, suggestive of a concurrent consumptive process. To define the relationship between coagulopathy and hepatocellular tropism, we compared infection and disease in Fah^−/−, Rag2^−/−, and Il2rɣ^−/− mice engrafted with human hepatocytes (hFRG mice) and rhesus macaques using a highly pathogenic African YFV strain. YFV infection of macaques and hFRG mice caused substantial hepatocyte infection, liver damage, and coagulopathy as defined by virological, clinical, and pathological criteria. However, only macaques developed a consumptive coagulopathy whereas YFV-infected hFRG mice did not. Thus, infection of cell types other than hepatocytes likely contributes to the consumptive coagulopathy associated with severe YF in primates and humans. These findings expand our understanding of viral hemorrhagic disease and associated coagulopathy and suggest directions for clinical management of severe YF cases.

Extracellular DNA-A Danger Signal Triggering Immunothrombosis

Clotting and inflammation are effective danger response patterns positively selected by evolution to limit fatal bleeding and pathogen invasion upon traumatic injuries. As a trade-off, thrombotic, and thromboembolic events complicate severe forms of infectious and non-infectious states of acute and chronic inflammation, i.e., immunothrombosis. Factors linked to thrombosis and inflammation include mediators released by platelet granules, complement, and lipid mediators and certain integrins. Extracellular deoxyribonucleic acid (DNA) was a previously unrecognized cellular component in the blood, which elicits profound proinflammatory and prothrombotic effects. Pathogens trigger the release of extracellular DNA together with other pathogen-associated molecular patterns. Dying cells in the inflamed or infected tissue release extracellular DNA together with other danger associated molecular pattern (DAMPs). Neutrophils release DNA by forming neutrophil extracellular traps (NETs) during infection, trauma or other forms of vascular injury. Fluorescence tissue imaging localized extracellular DNA to sites of injury and to intravascular thrombi. Functional studies using deoxyribonuclease (DNase)-deficient mouse strains or recombinant DNase show that extracellular DNA contributes to the process of immunothrombosis. Here, we review rodent models of immunothrombosis and the evolving evidence for extracellular DNA as a driver of immunothrombosis and discuss challenges and prospects for extracellular DNA as a potential therapeutic target.

PECAM-1 protects against DIC by dampening inflammatory responses via inhibiting macrophage pyroptosis and restoring vascular barrier integrity

Disseminated intravascular coagulation (DIC) is a frequent complication of sepsis that affects patient outcomes due to accompanying thrombo-inflammation and microvascular permeability changes. Platelet endothelial cell adhesion molecule-1 (PECAM-1), a cellular adhesion and signaling receptor that is expressed on both hematopoietic and endothelial cells, plays an important anti-inflammatory role in acute and chronic inflammatory disease models. Little is known, however, about role and mechanism of PECAM-1 in septic DIC. Here, we investigated whether PECAM-1 might play a protective role in hindering the development of septic DIC. Plasma levels of soluble PECAM-1 were markedly elevated in septic patients that developed DIC, with a correspondingly poorer outcome. PECAM-1 knockout exhibited more severe DIC and poorer outcome in the LPS induced- and cecal ligation and puncture-induced DIC model, which could be alleviated by tissue factor inhibitor. This phenomenon seemed to be equally linked to PECAM-1 expression by both endothelial and blood cells. Furthermore, PECAM-1 was found to exert its protective effect on developing septic DIC by the following 2 distinct mechanisms: the inhibition of macrophage pyroptosis and the acceleration of the restoration of the endothelial cell barrier. Taken together, these results implicate PECAM-1 as a potentially attractive target for the development of novel therapeutics to manage and treat septic DIC.

Both UFH and NAH alleviate shedding of endothelial glycocalyx and coagulopathy in LPS-induced sepsis

Sepsis commonly progresses to disseminated intravascular coagulation and induces the activation of heparanase (HPA) and the shedding of endothelial glycocalyx constituents, including syndecan-1 (SDC-1) and heparan sulphate (HS). However, the degradation of glycocalyx and its association with coagulation disorders remains undetermined. The present study aimed to evaluate the effect of unfractionated heparin (UFH) and N-acetylheparin (NAH), which is a non-anticoagulant heparin derivative, on endothelial glycocalyx and coagulation function in a lipopolysaccharide (LPS)-induced sepsis rat model, and to compare the differences observed in coagulation function between UFH and NAH. Experimental rats were randomly assigned to four groups: Control; LPS; UFH + LPS; and NAH + LPS. Rats were administered UFH or NAH and subsequently, ~1 min later, administered LPS (10 mg/kg; intravenous). The blood and lung tissues of rats were collected 0.5, 2 and 6 h after LPS injection, and were used for subsequent analysis. The results demonstrated that HPA activity and SDC-1 and HS levels increased, and this increase was associated with inflammatory cytokines and coagulation/fibrinolysis markers in the sepsis rat model. Histopathological examination was performed, and the lung injury score and lung wet/dry ratio indicated that UFH and NAH also significantly improved lung tissue injury. The results of the ELISA analysis demonstrated that UFH and NAH treatment: i) significantly decreased the levels of inflammatory cytokines including tumor necrosis factor-α and interleukin-6; ii) inhibited HPA activity and protected the integrity of the glycocalyx, which was identified by decreased HS and SDC-1 levels; and iii) decreased the levels of prothrombin fragment 1+2, thrombin-antithrombin complex, and plasminogen activator inhibitor-1 and increased the levels of fibrinogen and antithrombin-III. Preconditioning with UFH decreased the plasma activated partial thromboplastin time. These results indicated that UFH and NAH may alleviate sepsis-induced coagulopathy, and this effect may have been due to an inhibition of HPA activity and decrease in the shedding of the endothelial glycocalyx.

Understanding Infection-Induced Thrombosis: Lessons Learned From Animal Models

Thrombosis is a common consequence of infection that is associated with poor patient outcome. Nevertheless, the mechanisms by which infection-associated thrombosis is induced, maintained and resolved are poorly understood, as is the contribution thrombosis makes to host control of infection and pathogen spread. The key difference between infection-associated thrombosis and thrombosis in other circumstances is a stronger inflammation-mediated component caused by the presence of the pathogen and its products. This inflammation triggers the activation of platelets, which may accompany damage to the endothelium, resulting in fibrin deposition and thrombus formation. This process is often referred to as thrombo-inflammation. Strikingly, despite its clinical importance and despite thrombi being induced to many different pathogens, it is still unclear whether the mechanisms underlying this process are conserved and how we can best understand this process. This review summarizes thrombosis in a variety of models, including single antigen models such as LPS, and infection models using viruses and bacteria. We provide a specific focus on Salmonella Typhimurium infection as a useful model to address all stages of thrombosis during infection. We highlight how this model has helped us identify how thrombosis can appear in different organs at different times and thrombi be detected for weeks after infection in one site, yet largely be resolved within 24 h in another. Furthermore, we discuss the observation that thrombi induced to Salmonella Typhimurium are largely devoid of bacteria. Finally, we discuss the value of different therapeutic approaches to target thrombosis, the potential importance of timing in their administration and the necessity to maintain normal hemostasis after treatment. Improvements in our understanding of these processes can be used to better target infection-mediated mechanisms of thrombosis.

Repeat dose exposure of PM2.5 triggers the disseminated intravascular coagulation (DIC) in SD rats

Epidemiological evidence suggests that fine particulate matter (PM_2.5) in air pollution promotes the formation of deep venous thrombosis. However, no evidence is available on the effects of PM_2.5 lead to disseminated intravascular coagulation (DIC). For the first time, this study explored the effects of PM_2.5 on DIC via coagulation disorders in vivo. SD rats received intratracheal instillation of PM_2.5 once every three days for one month. Doppler ultrasound showed that the pulmonary valve (PV) and aortic valve (AV) peak flow were decreased after exposure to PM_2.5. Fibrin deposition and bleeding were observed in lung tissue and vascular endothelial injury was found after exposure to PM_2.5. Expression of thrombomodulin (TM) in vessel was downregulated after PM_2.5-treated, whereas the levels of proinflammatory factors and adhesion molecules (IL-6, IL-1β, CRP, ICAM-1 and VCAM-1) were markedly elevated after exposure to PM_2.5. Tissue factor (TF) and the coagulation factor of FXa were increased, while vWF was significantly lowered induced by PM_2.5. Thrombin-antithrombin complex (TAT) and fibrinolytic factor (t-PA) were elevated, while there was no significantly change in the expression of anticoagulant factors (TFPI and AT-III). To clarify the relationship between PM_2.5 and DIC, we examined the general diagnostic indices of DIC: PM_2.5 prolonged PT and increased the expression of D-dimer but decreased platelet count and fibrinogen. In addition, the gene levels of JAK1 and STAT3 showed an upward trend, whereas there was little effect on JAK2 expression. And inflammatory factors (IL-6, IL-1β and TNF) in blood vessels of were up-reglated in PM_2.5-treated rats. In summary, our results found that PM_2.5 could induce inflammatory response, vascular endothelial injury and prothrombotic state, eventually resulted in DIC. It will provide new evidence for a link between PM_2.5 and cardiovascular disease.

Suppression of plasminogen activator inhibitor-1 (PAI-1) activity by crocin ameliorates lipopolysaccharide-induced thrombosis in rats

The imbalance between clot formation and fibrinolysis is mainly attributed to increased levels of plasminogen activator inhibitor type 1 (PAI-1), an inhibitor of fibrinolysis closely involved in inflammatory responses such as septic shock. This increase is mediated by many factors, including reactive oxygen species (ROS). The present study was designed to evaluate the prophylactic effect of crocin, a potent natural antioxidant, on PAI-1 in the rat model of endotoxic shock. Lipopolysaccharide-infused rats (500 μg/kg) showed significant changes in thrombosis-related haematological parameters such as decrease of platelet blood counts and increase (7 fold) of PAI-1 concentration in blood plasma. No effect on t-PA activity was observed. Crocin administration in two different doses (10 mg/kg and 100 mg/kg) 30 min prior to the injection of LPS, inhibited the reduction of platelet counts and ameliorated the concentration of PAI-1 in the liver and the brain. Moreover, crocin inhibited the deposition of fibrin in the renal glomeruli. No significant changes were recorded in the healthy groups of crocin (10 mg/kg and 100 mg/kg) compared to the control group. These data demonstrate the potential of crocin to prevent LPS-induced organ injury and suggest it is worthwhile to investigate the use of antioxidants for the treatment of septicemia.

Tie2 protects the vasculature against thrombus formation in systemic inflammation

Disordered coagulation contributes to death in sepsis and lacks effective treatments. Existing markers of disseminated intravascular coagulation (DIC) reflect its sequelae rather than its causes, delaying diagnosis and treatment. Here we show that disruption of the endothelial Tie2 axis is a sentinel event in septic DIC. Proteomics in septic DIC patients revealed a network involving inflammation and coagulation with the Tie2 antagonist, angiopoietin-2 (Angpt-2), occupying a central node. Angpt-2 was strongly associated with traditional DIC markers including platelet counts, yet more accurately predicted mortality in 2 large independent cohorts (combined N = 1,077). In endotoxemic mice, reduced Tie2 signaling preceded signs of overt DIC. During this early phase, intravital imaging of microvascular injury revealed excessive fibrin accumulation, a pattern remarkably mimicked by Tie2 deficiency even without inflammation. Conversely, Tie2 activation normalized prothrombotic responses by inhibiting endothelial tissue factor and phosphatidylserine exposure. Critically, Tie2 activation had no adverse effects on bleeding. These results mechanistically implicate Tie2 signaling as a central regulator of microvascular thrombus formation in septic DIC and indicate that circulating markers of the Tie2 axis could facilitate earlier diagnosis. Finally, interventions targeting Tie2 may normalize coagulation in inflammatory states while averting the bleeding risks of current DIC therapies.

Class A CpG Oligonucleotide Priming Rescues Mice from Septic Shock via Activation of Platelet-Activating Factor Acetylhydrolase

Sepsis is a life-threatening, overwhelming immune response to infection with high morbidity and mortality. Inflammatory response and blood clotting are caused by sepsis, which induces serious organ damage and death from shock. As a mechanism of pathogenesis, platelet-activating factor (PAF) induces excessive inflammatory responses and blood clotting. In this study, we demonstrate that a Class A CpG oligodeoxynucleotide (CpG-A₁₅₈₅) strongly induced PAF acetylhydrolase, which generates lyso-PAF. CpG-A₁₅₈₅ rescued mice from acute lethal shock and decreased fibrin deposition, a hallmark of PAF-induced disseminated intravascular coagulation. Furthermore, CpG-A₁₅₈₅ improved endotoxin shock induced by lipopolysaccharide, which comprises the cell wall of Gram-negative bacteria and inhibits inflammatory responses induced by cytokines such as interleukin-6 and tumor necrosis factor-α. These results suggest that CpG-A₁₅₈₅ is a potential therapeutic target to prevent sepsis-related induction of PAF.

Non-Lethal Endotoxin Injection: A Rat Model of Hypercoagulability

Systemic inflammation co-activates coagulation, which unchecked culminates in a lethal syndrome of multi-organ microvascular thrombosis known as disseminated intravascular coagulation (DIC). We studied an endotoxin-induced inflammatory state in rats to identify biomarkers of hemostatic imbalance favoring hypercoagulability. Intraperitoneal injection of LPS at 15 mg/kg body weight resulted in peripheral leukopenia and widespread neutrophilic sequestration characteristic of an acute systemic inflammatory response. Early indicators of hemostatic pathway activation developed within 4 hours, including increased circulating concentrations of procoagulant extracellular vesicles (EVs), EVs expressing endothelial cell and platelet membrane markers, and high concentration of soluble intercellular adhesion molecule-1 (sICAM-1), plasminogen activator inhibitor-1 (PAI-1), and D-dimers. Inflammation persisted throughout the 48-hour observation period; however, increases were found in a subset of serum microRNA (miRNA) that coincided with gradual resolution of hemostatic protein abnormalities and reduction in EV counts. Dose-adjusted LPS treatment in rats provides a time-course model to develop biomarker profiles reflecting procoagulant imbalance and rebalance under inflammatory conditions.

Catalpol restores LPS-elicited rat microcirculation disorder by regulation of a network of signaling involving inhibition of TLR-4 and SRC

LPS-induced microvascular hyperpermeability and hemorrhage play a key role in the development of sepsis, the attenuation of which might be an important strategy to prevent sepsis. However, the current clinical therapies have proven to be inefficient in improving the prognosis for patients with sepsis. Catalpol, an iridoid glycoside extracted from the roots of Rehmannia, has been reported to protect against LPS-induced acute lung injury through a Toll-like receptor-4 (TLR-4)-mediated NF-κB signaling pathway. However, it is still unknown whether catalpol can be an effective treatment to ameliorate the LPS-induced microvascular disorder. The present study aimed to investigate the impact of catalpol on LPS-induced mesenteric microvascular disorder and its underlying mechanism. Male Wistar rats were challenged by infusion of LPS (10 mg·kg^-1·h^-1) through the left femoral vein for 120 min. Post-treatment with catalpol (10 mg/kg) alleviated the LPS-induced microvascular hyperpermeability and hemorrhage; reduced mortality; ameliorated the alteration in the distribution of claudin-5 and the junctional adhesion molecule-1, as well as the degradation of collagen IV and laminin; and attenuated the increase of TLR-4 level, phosphorylations of Src tyrosine kinase, phosphatidyl inositol 3-kinase, focal adhesion kinase, and cathepsin B activation. In vitro study in human umbilical vein endothelial cells verified these results and further revealed that inhibition of TLR-4 and Src each simulated some, but not all, of the effects that catalpol exerted. Besides, surface plasmon resonance showed that catalpol could directly bind to TLR-4 and Src. These results demonstrated that catalpol was able to ameliorate the LPS-induced microvascular barrier damage and hemorrhage by targeting both TLR-4 and Src, thus attenuating the phosphorylation of Src kinase, phosphatidyl inositol 3-kinase, and focal adhesion kinase, as well as cathepsin B activation.

Factor XI Deficiency Alters the Cytokine Response and Activation of Contact Proteases during Polymicrobial Sepsis in Mice

Sepsis, a systemic inflammatory response to infection, is often accompanied by abnormalities of blood coagulation. Prior work with a mouse model of sepsis induced by cecal ligation and puncture (CLP) suggested that the protease factor XIa contributed to disseminated intravascular coagulation (DIC) and to the cytokine response during sepsis. We investigated the importance of factor XI to cytokine and coagulation responses during the first 24 hours after CLP. Compared to wild type littermates, factor XI-deficient (FXI^-/-) mice had a survival advantage after CLP, with smaller increases in plasma levels of TNF-α and IL-10 and delayed IL-1β and IL-6 responses. Plasma levels of serum amyloid P, an acute phase protein, were increased in wild type mice 24 hours post-CLP, but not in FXI^-/- mice, supporting the impression of a reduced inflammatory response in the absence of factor XI. Surprisingly, there was little evidence of DIC in mice of either genotype. Plasma levels of the contact factors factor XII and prekallikrein were reduced in WT mice after CLP, consistent with induction of contact activation. However, factor XII and PK levels were not reduced in FXI^-/- animals, indicating factor XI deficiency blunted contact activation. Intravenous infusion of polyphosphate into WT mice also induced changes in factor XII, but had much less effect in FXI deficient mice. In vitro analysis revealed that factor XIa activates factor XII, and that this reaction is enhanced by polyanions such polyphosphate and nucleic acids. These data suggest that factor XI deficiency confers a survival advantage in the CLP sepsis model by altering the cytokine response to infection and blunting activation of the contact (kallikrein-kinin) system. The findings support the hypothesis that factor XI functions as a bidirectional interface between contact activation and thrombin generation, allowing the two processes to influence each other.

miR-96 and miR-330 overexpressed and targeted AQP5 in lipopolysaccharide-induced rat lung damage of disseminated intravascular coagulation

Disseminated intravascular coagulation (DIC) is a severe clinical condition that can lead to or aggravate the development of multiple organ dysfunction syndrome. Of all types of organ damage, lung damage is the most frequent and most severe. In DIC patients, lung damage is primarily characterized by pulmonary edema. Aquaporin (AQP) 5 is the chief AQP in the lungs and it plays a key role in many processes, including water transport in normal and abnormal lungs. Here we demonstrate that expression of AQP5 and two microRNAs, miR-96 and miR-330, in rat lung of lipopolysaccharide (LPS)-induced DIC. We also show that both miR-96 and miR-330 can regulate the expression of AQP5 by binding with its 3'-untranslated region (UTR) by luciferase activity assay. These results suggest that microRNAs are involved in lung damage in LPS-induced rat DIC and can be a potential target for molecular therapy.

Evidence for radiation-induced disseminated intravascular coagulation as a major cause of radiation-induced death in ferrets

PURPOSE

The studies reported here were performed as part of a program in space radiation biology in which proton radiation like that present in solar particle events, as well as conventional gamma radiation, were being evaluated in terms of the ability to affect hemostasis.

METHODS AND MATERIALS

Ferrets were exposed to 0 to 2 Gy of whole-body proton or gamma radiation and monitored for 30 days. Blood was analyzed for blood cell counts, platelet clumping, thromboelastometry, and fibrin clot formation.

RESULTS

The lethal dose of radiation to 50% of the population (LD50) of the ferrets was established at ∼ 1.5 Gy, with 100% mortality at 2 Gy. Hypocoagulability was present as early as day 7 postirradiation, with animals unable to generate a stable clot and exhibiting signs of platelet aggregation, thrombocytopenia, and fibrin clots in blood vessels of organs. Platelet counts were at normal levels during the early time points postirradiation when coagulopathies were present and becoming progressively more severe; platelet counts were greatly reduced at the time of the white blood cell nadir of 13 days.

CONCLUSIONS

Data presented here provide evidence that death at the LD50 in ferrets is most likely due to disseminated intravascular coagulation (DIC). These data question the current hypothesis that death at relatively low doses of radiation is due solely to the cell-killing effects of hematopoietic cells. The recognition that radiation-induced DIC is the most likely mechanism of death in ferrets raises the question of whether DIC is a contributing mechanism to radiation-induced death at relatively low doses in large mammals.

Novel biomarkers for early prediction of sepsis-induced disseminated intravascular coagulation in a mouse cecal ligation and puncture model

Introduction

The objective of this study was to identify biomarkers of sepsis-induced disseminated intravascular coagulation (DIC) among platelet-derived factors using biotin label-based custom protein microarray technology in a mouse cecal ligation and puncture (CLP) model.

Methods

KM mice were randomized into sham-operated and CLP groups. Blood samples were obtained immediately and at 1 h, 2 h, 6 h, 12 h, 24 h, 48 h and 72 h after establishment of the CLP for platelet count, coagulation assay and blood chemistry. Lung and mesentery tissues were examined histologically at all corresponding time points, looking for microthrombus formation. Serial protein microarray analysis was performed to detect platelet-derived factors.

Results

The survival rate 72 h post-CLP was 15%, but there was no mortality among the sham-operated mice. Compared with the sham group, the platelet count (n = 5, p < 0.05), fibrinogen concentration (n = 5, p < 0.05) and alanine aminotransferase level of the CLP group began to decrease significantly at 6 h post-CLP. Significant prolongation of prothrombin time (n = 5, p < 0.05) and activated partial thromboplastin time (n = 5, p < 0.05) and elevation of D-dimer (n = 5, p < 0.05) occurred after 6 h post-CLP. On histology, microthrombus formation in lung and mesentery tissue was observed in the CLP groups 6 h post-CLP and had become significant and extensive 12 h post-CLP (n = 5, p < 0.05). On protein microarray analysis and ELISA, thrombospondin (TSP), tissue inhibitor of metalloproteinase 1 (TIMP-1) and thymus chemokine-1 (TCK-1) all increased during the first 2 h post-CLP, then remained at a higher level than in the sham group for 72 h post-CLP (n = 5, p < 0.05).

Conclusions

TSP, TIMP-1 and TCK-1 are elevated in the early stage of sepsis-induced DIC in a mouse CLP model and may be considered early markers for sepsis-induced DIC.

Similarities in thromboelastometric (ROTEM®) findings between humans and baboons

INTRODUCTION

Interest in visco-elastic testing in different clinical scenarios has increased but few data are available on thromboelastometric findings in primates.

MATERIALS AND METHODS

Blood cell count (hemoglobin, hematocrit, platelet count), coagulation parameters (prothrombin time, International Normalized Ratio, fibrinogen), and ROTEM® (Tem International GmbH, Munich, Germany) variables were analyzed using blood from 25 anesthetized male baboons and 21 non-anesthetized healthy volunteers. The platelet component of the clot was calculated as the difference in maximum clot elasticity (MCE) between the whole blood clot (EXTEM test) and the fibrin-based clot (FIBTEM test). In subgroups of each species, 10 μg abciximab was added to the regular FIBTEM reagent (cytochalasin D) for additional platelet inhibition.

RESULTS

Blood cell count was comparable between humans and primates. Both fibrinogen concentration (p<0.0001) and maximum clot firmness (MCF) in FIBTEM assays were significantly lower in baboons (p>0.0001, and p=0.006, respectively). PT, INR, and clotting time in NATEM assays were significantly prolonged in humans compared with baboons. MCF in NATEM, EXTEM and INTEM assays was not different between baboons and humans. Clot lysis in NATEM, EXTEM and INTEM assays was significantly higher in humans (p<0.0001). In contrast FIBTEM clot lysis was significantly higher in baboons (p=0.01). Addition of abciximab into the FIBTEM assay resulted in a significant reduction in MCF and MCE (p<0.001) and, consequently, the platelet component increased similar in both humans and baboons (p<0.001).

CONCLUSION

Activated ROTEM® tests revealed broad similarities between humans and baboons. ROTEM® assays developed for use in humans can also be used in baboons.