Thrombin and vascular inflammation

Efficacy of unfractionated heparin in patients with moderate sepsis-induced coagulopathy: An observational study

INTRODUCTION

The 2021 Surviving Sepsis Campaign guidelines recommend low-molecular-weight heparin for the prevention of venous thromboembolism in sepsis. However, observational studies suggest that anticoagulants as a whole may benefit severely ill sepsis patients with coagulopathy, but the optimal targets of unfractionated heparin remain unclear. This study investigated which sepsis patients could most benefit from unfractionated heparin.

MATERIALS AND METHODS

In this retrospective observational study, we identified adult sepsis patients requiring urgent hospitalization from 2006 to 2019 using a large-scale Japanese medical database. Patients were divided into two groups: those receiving unfractionated heparin within 72 h of admission and those who did not. We compared in-hospital mortality, major bleeding complications, and thromboembolic events between these groups using a multivariate logistic regression model adjusted for patient and treatment variables. Additionally, we assessed the association between heparin administration and in-hospital mortality across various subgroups.

RESULTS

Among 30,342 sepsis patients, 2520 received early heparin administration, and 27,822 did not. Multivariate logistic regression revealed a significant association between heparin and reduced in-hospital mortality (adjusted OR: 0.735, 95 % CI: 0.596-0.903) but no significant association with major bleeding and thromboembolic risk (adjusted OR: 1.137, 1.243; 95 % CI: 0.926-1.391, 0.853-1.788, respectively). Subgroup analyses suggested significant survival benefits associated with heparin only in the sepsis patients with moderate coagulopathy and sepsis-induced coagulopathy scores of 3 or 4 (adjusted OR: 0.452, 0.625; 95 % CI: 0.265-0.751, 0.410-0.940, respectively).

CONCLUSIONS

Early heparin administration upon admission is associated with lower in-hospital mortality, especially in moderate sepsis-induced coagulopathy, and no significant increase in complications.

Gestodene, a novel positive allosteric modulator of PAR1, enhances PAR1-mediated human platelet aggregation

Background: Protease-activated receptor 1 (PAR1) is expressed in human platelets and can be activated by low concentrations of thrombin. Vorapaxar, a selective antagonist of PAR1, inhibits thrombin-induced calcium mobilization in human platelet, which is associated with an increased risk of bleeding. Conversely, the administration of a positive allosteric modulator (PAM) of PAR1 may pose a substantial risk of thrombosis due to inducing excessive platelet activation. In this study, we discovered a novel PAM of PAR1 and investigated the effect of enhanced PAR1 activation by PAM of PAR1 on platelet activation. Methods: To find PAMs of PAR1, a cell-based screen was performed in HT29 cells, and finally, gestodene, an oral contraceptive drug (OC), was identified as a novel PAM of PAR1. The mechanism of action of gestodene and its effects on platelet activation were investigated in human megakaryocytic leukemia cell line MEG-01 cells and human platelet. Results: Gestodene enhanced both thrombin- and PAR1-activating peptide (AP)-induced intracellular calcium levels in a dose-dependent manner without altering PAR2 and PAR4 activity. Gestodene significantly increased PAR1-AP-induced internalization of PAR1 and phosphorylation of ERK1/2, and the enhancing effects were significantly blocked by vorapaxar. Furthermore, gestodene potently increased PAR1-AP induced morphological changes in MEG-01 cells. Remarkably, in human blood, gestodene exerted a robust augmentation of PAR1-AP-induced platelet aggregation, and vorapaxar effectively attenuated the gestodene-induced enhancement of platelet aggregation mediated by PAR1. Conclusion: Gestodene is a selective PAM of PAR1 and suggest one possible mechanism for the increased risk of venous thromboembolism associated with OCs containing gestodene.

Evaluation of Cordyceps militaris steroids as anti-inflammatory agents to combat the Covid-19 cytokine storm: a bioinformatics and structure-based drug designing approach

Since the SARS-CoV-2 epidemic, researchers have been working on figuring out ways to tackle multi-organ failure and hyperinflation, which are brought on by a cytokine storm. Angiotensin-converting enzyme 2 (ACE2), a SARS-CoV-2 spike glycoprotein's cellular receptor, is involved in complicated molecular processes that result in hyperinflammation. Cordyceps militaris is one of the traditional Chinese medicines that is used as an immune booster, and it has exhibited efficacy in lowering blood glucose levels, seminal emissions, and infertility. In the current study, we explored the potential of Cordyceps militaris steroids as key agents in managing the anger of cytokine storm in Covid-19 using network ethnopharmacological techniques and structure-based drug designing approaches. The steroids present in Cordyceps militaris were initially screened against the targets involved in inflammatory pathways. The results revealed that out of 16 steroids, 5 may be effective against 17 inflammatory pathways by targeting 11 pathological proteins. Among the five steroids, beta-sitosterol, Cholest-5-en-3β-ol, 3β, and 7α-Dihydroxycholest-5-ene were found to interact with thrombin (F2), an important protein reported to reduce the severity of inflammatory mediators and Cholest-4-en-3-one was found to target Glucocorticoid receptor (NR3C1). The top docked steroid displayed key interactions with both targets, which retained key interactions throughout the 100 ns simulation period. These compounds were also shown high binding free energy scores in water swap studies. Based on obtained results the current study suggests the use of Cordyceps militaris as an add-on therapy that may reduce the progression of inflammatory co-morbidities among patients infected with SARS-CoV-2.Communicated by Ramaswamy H. Sarma.

Engineering Pancreatic Islets to Transiently Codisplay on Their Surface Thrombomodulin and CD47 Immunomodulatory Proteins as a Means of Mitigating Instant Blood-Mediated Inflammatory Reaction following Intraportal Transplantation

Most pancreatic islets are destroyed immediately after intraportal transplantation by an instant blood-mediated inflammatory reaction (IBMIR) generated through activation of coagulation, complement, and proinflammatory pathways. Thus, effective mitigation of IBMIR may be contingent on the combined use of agents targeting these pathways for modulation. CD47 and thrombomodulin (TM) are two molecules with distinct functions in regulating coagulation and proinflammatory responses. We previously reported that the islet surface can be modified with biotin for transient display of novel forms of these two molecules chimeric with streptavidin (SA), that is, thrombomodulin chimeric with SA (SA-TM) and CD47 chimeric with SA (SA-CD47), as single agents with improved engraftment following intraportal transplantation. This study aimed to test whether islets can be coengineered with SA-TM and SA-CD47 molecules as a combinatorial approach to improve engraftment by inhibiting IBMIR. Mouse islets were effectively coengineered with both molecules without a detectable negative impact on their viability and metabolic function. Coengineered islets were refractory to destruction by IBMIR ex vivo and showed enhanced engraftment and sustained function in a marginal mass syngeneic intraportal transplantation model. Improved engraftment correlated with a reduction in intragraft innate immune infiltrates, particularly neutrophils and M1 macrophages. Moreover, transcripts for various intragraft procoagulatory and proinflammatory agents, including tissue factor, HMGB1 (high-mobility group box-1), IL-1β, IL-6, TNF-α, IFN-γ, and MIP-1α, were significantly reduced in coengineered islets. These data demonstrate that the transient codisplay of SA-TM and SA-CD47 proteins on the islet surface is a facile and effective platform to modulate procoagulatory and inflammatory responses with implications for both autologous and allogeneic islet transplantation.

Chronoamperometric interrogation of an electrochemical aptamer-based sensor with tetrahedral DNA nanostructure pendulums for continuous biomarker measurements

Tetrahedral DNA nanostructure (TDN) is highly promising in developing electrochemical aptamer-based (E-AB) sensors for biomolecular detection, owing to its inherit programmability, spatial orientation and structural robustness. However, current interrogation strategies applied for TDN-based E-AB sensors, including enzyme-based amperometry, voltammetry, and electrochemical impedance spectroscopy, either require complicated probe design or suffer from limited applicability or selectivity. In this study, a TDN pendulum-empowered E-AB sensor interrogated by chronoamperometry for reagent-free and continuous monitoring of a blood clotting enzyme, thrombin, was developed. TDN pendulums with extended aptamer sequences at three vertices were immobilized on a gold electrode via a thiolated double-stranded DNA (dsDNA) at the fourth vertex, and their motion is modulated by the bonding of target thrombin to aptamers. We observed a significantly amplified signalling output on our sensor based on the TDN pendulum compared to E-AB sensors modified with linear pendulums. Moreover, our sensor achieved highly selective and rapidly responsive measurement of thrombin in both PBS and artificial urine, with a wide dynamic range from 1 pM to 10 nM. This study shows chronoamperometry-enabled continuous biomarker monitoring on a sub-second timescale with a drift-free baseline, demonstrating a novel approach to accurately detect molecular dynamics in real time.

Role of Serine Protease Inhibitors A1 and A3 in Ocular Pathologies

Serine protease inhibitors A1 (SerpinA1) and A3 (SerpinA3) are important members of the serpin family, playing crucial roles in the regulation of serine proteases and influencing various physiological processes. SerpinA1, also known as α-1-antitrypsin, is a versatile glycoprotein predominantly synthesized in the liver, with additional production in inflammatory and epithelial cell types. It exhibits multifaceted functions, including immune modulation, complement activation regulation, and inhibition of endothelial cell apoptosis. SerpinA3, also known as α-1-antichymotrypsin, is expressed both extracellularly and intracellularly in various tissues, particularly in the retina, kidney, liver, and pancreas. It exerts anti-inflammatory, anti-angiogenic, antioxidant, and antifibrotic activities. Both SerpinA1 and SerpinA3 have been implicated in conditions such as keratitis, diabetic retinopathy, age-related macular degeneration, glaucoma, cataracts, dry eye disease, keratoconus, uveitis, and pterygium. Their role in influencing metalloproteinases and cytokines, as well as endothelial permeability, and their protective effects on Müller cells against oxidative stress further highlight their diverse and critical roles in ocular pathologies. This review provides a comprehensive overview of the etiology and functions of SerpinA1 and SerpinA3 in ocular diseases, emphasizing their multifaceted roles and the complexity of their interactions within the ocular microenvironment.

An aggregation-induced emission sensor combined with UHPLC-Q-TOF/MS for fast identification of anticoagulant active ingredients from traditional Chinese medicine

Xuebijing injection (XBJ) has a good therapeutic effect on the patients with severe coronavirus disease, but the material basis of XBJ with the anticoagulant effect to improve the coagulopathy and thromboembolism is still unclear. Herein, we developed a new strategy based on aggregation-induced emission (AIE) for monitoring thrombin activity and screening thrombin inhibitors from XBJ. The molecule AIE603 and the thrombin substrate peptide S-2238 were formed into AIE nanoparticle (AIENP) which emitted notable fluorescence due to the restriction of intramolecular motions. In the presence of thrombin, AIENP was specifically hydrolyzed and AIE603 was released from AIENP, leading to the decrease of fluorescence intensity. Furthermore, AIENP was combined with ultra-high performance liquid chromatography-fraction collector (UHPLC-FC) and ultra-high performance liquid chromatography quadrupole-time-of-flight mass spectrometry (UHPLC-Q-TOF/MS) for separation, preparation, screening and identification of the thrombin inhibitors from XBJ, a total of 58 chemical constituents were identified, among which 6 compounds possessed higher anticoagulant activity. Notably, the overall inhibition rate of the 6 mixed standards was equivalent to about 60% of the inhibition rate of XBJ. Therefore, this work provides a novel, cheap and simple method for monitoring thrombin activity and is promising to screen active substances from traditional Chinese medicines.

Time-dependent dual effect of microglia in ischemic stroke

Stroke, the third leading cause of death and disability worldwide, is classified into ischemic or hemorrhagic, in which approximately 85% of strokes are ischemic. Ischemic stroke occurs as a result of arterial occlusion due to embolus or thrombus, with ischemia in the perfusion territory supplied by the occluded artery. The traditional concept that ischemic stroke is solely a vascular occlusion disorder has been expanded to include the dynamic interaction between microglia, astrocytes, neurons, vascular cells, and matrix components forming the "neurovascular unit." Acute ischemic stroke triggers a wide spectrum of neurovascular disturbances, glial activation, and secondary neuroinflammation that promotes further injury, ultimately resulting in neuronal death. Microglia, as the resident macrophages in the central nervous system, is one of the first responders to ischemic injury and plays a significant role in post-ischemic neuroinflammation. In this review, we reviewed the mechanisms of microglia in multiple stages of post-ischemic neuroinflammation development, including acute, sub-acute and chronic phases of stroke. A comprehensive understanding of the dynamic variation and the time-dependent role of microglia in post-stroke neuroinflammation could aid in the search for more effective therapeutics and diagnostic strategies for ischemic stroke.

Plasma Heparin Cofactor II Activity Is Inversely Associated with Hepatic Fibrosis of Non-Alcoholic Fatty Liver Disease in Patients with Type 2 Diabetes Mellitus

AIMS

Thrombin exerts various pathophysiological functions by activating protease-activated receptors (PARs), and thrombin-induced activation of PARs promotes the development of non-alcoholic fatty liver disease (NAFLD). Since heparin cofactor II (HCII) specifically inactivates thrombin action, we hypothesized that plasma HCII activity correlates with the severity of NAFLD.

METHODS

A cross-sectional study was conducted. Plasma HCII activity and noninvasive clinical markers of hepatic fibrosis including fibrosis-4 (FIB-4) index, NAFLD fibrosis score (NFS) and aspartate aminotransferase-to-platelet ratio index (APRI) were determined in 305 Japanese patients with type 2 diabetes mellitus (T2DM). The relationships between plasma HCII activity and the clinical markers were statistically evaluated.

RESULTS

Multiple regression analysis including confounding factors showed that plasma HCII activity independently contributed to decreases in FIB-4 index (p＜0.001), NFS (p＜0.001) and APRI (p=0.004). In addition, logistic regression analysis for the prevalence of advanced hepatic fibrosis defined by the cutoff points of the clinical scores showed that plasma HCII activity was the sole and common negative factor for prevalence of advanced hepatic fibrosis (FIB-4 index: p=0.002, NFS: p=0.026 and APRI: p=0.012).

CONCLUSIONS

Plasma HCII activity was inversely associated with clinical hepatic fibrosis indices including FIB-4 index, NFS and APRI and with the prevalence of advanced hepatic fibrosis in patients with T2DM. The results suggest that HCII can serve as a novel biomarker for assessment of hepatic fibrosis of NAFLD in patients with T2DM.

Targeting endothelial coagulation signaling ameliorates liver obstructive cholestasis and dysfunctional angiogenesis

Cholestatic fibrogenesis is a pathobiological process in which cumulative injury to the bile ducts coincides with progressive liver fibrosis. The pathobiologic mechanisms underlying fibrogenesis and disease progression remain poorly understood. Currently, there is no effective treatment for liver fibrosis. In this study, we discovered that components of the coagulation cascade were associated with the advanced progression of obstructive cholestasis, and anticoagulant therapy could improve liver cholestasis-induced fibrosis. In a mouse model of common bile duct ligation (BDL), which mimics cholestatic liver injury, RNA sequencing analysis revealed an increased expression of coagulation factors in endothelial cells. Pharmacological targeting of the coagulation signaling by hirudin, an anticoagulatory antagonist of thrombin, ameliorated obstructive cholestasis, and attenuated liver fibrosis symptoms. Hirudin attenuated fibrosis-associated angiogenesis, endothelial-to-mesenchymal transition (EndMT), and tissue hypoxia and reduced liver inflammation after BDL. Furthermore, hirudin suppressed YAP (Yes-associated protein) signaling and its downstream effectors in vascular endothelial cells, which are considered with profibrotic characteristics. In conclusion, we demonstrated that pharmacological targeting of coagulation signaling by hirudin has the potential to alleviate liver obstructive cholestasis and fibrosis.

Pleiotropic effects of NOACs with focus on edoxaban: scientific findings and potential clinical implications

Non-vitamin K antagonist oral anticoagulants (NOACs) are well-established as inhibitors of factor Xa (FXa) and thrombin in the treatment and prevention of thrombosis. However, there is growing evidence that beneficial outcomes might be based on additional pleiotropic effects beyond anticoagulation. FXa and thrombin are also known to activate protease-activated receptors (PARs), which can mediate pro-inflammatory and pro-fibrotic effects. Since PAR‑1 and PAR‑2 play an important role in the development of atherosclerosis, the inhibition of this pathway represents an interesting potential target for preventing the progression of atherosclerosis and fibrosis. This review focuses on potential pleiotropic effects of FXa inhibition with edoxaban seen in a variety of studies in different in vitro and in vivo test systems. As common findings from these experiments, edoxaban was able to attenuate FXa- and thrombin-induced pro-inflammatory and pro-fibrotic effects and decrease pro-inflammatory cytokine expression. In some, but not all experiments edoxaban was also shown to decrease the levels of PAR‑1 and PAR‑2 expression. Further studies are required to clarify the clinical implications of the pleiotropic effects mediated by NOACs.

Applications and future of aptamers that achieve rapid-onset anticoagulation

In this short Perspective, we discuss the history of, and recent progress toward, the development of aptamers that can serve as rapid onset anticoagulants during cardiopulmonary bypass (CPB), extracorporeal membrane oxygenation (ECMO), and catheter-based diagnostic and interventional procedures, several million of which are performed each year worldwide. Aptamer anticoagulants provide potent and antidote-controllable anticoagulation and have low immunogenicity. New methods of aptamer isolation and engineering have not only improved the quality of aptamers, but also accelerated their development. Unfortunately, no aptamer identified to date can produce an anticoagulant effect as potent as that produced by unfractionated heparin (UFH), the standard anticoagulant for CPB. We have suggested several possible strategies to amplify the anticoagulant potency of existing aptamer anticoagulants.

Liver protection and hemostatic effects of medicinal plant Arnebia euchroma (Royle) I.M.Johnst extract in a rat model

ETHNOPHARMACOLOGICAL RELEVANCE

Arnebia euchroma (Royle) I.M.Johnst. (AE) is a Chinese medicinal herb that is traditionally used to treat various circulatory diseases. It exhibits certain effects, such as the promotion of blood circulation and cooling, rash clearance, and detoxification.

AIM OF THE STUDY

This study was designed to explore the hepatoprotective and hemostatic effects of the ethyl acetate extract of AE in rats with carbon tetrachloride (CCl4)-induced liver injury.

MATERIALS AND METHODS

Wistar rats were treated via oral gavage with different doses of the ethyl acetate extract of AE (3.5, 7, or 14 g kg^-1·day^-1) for 14 consecutive days, following which hemostatic and liver function tests were conducted. For the hemostatic tests, the platelet count, blood platelet aggregation, blood platelet adhesion to fibrinogen, platelet factor 4 (PF-4) secretion from blood platelets, prothrombin time (PT), activated partial thromboplastin time (aPTT), thrombin time (TT), and fibrinogen levels were measured at the end of the treatment period. For the liver function tests, 0.25 mL/200 g (1.25 mL kg^-1·day^-1) of olive oil was injected into the abdominal cavity of the control rats, whereas 15% CCl₄ plus olive oil (prescription: 7.5 mL CCl₄ + 42.5 olive oil) was injected into that of the treated rats at 1 h after extract administration on day 6, 13, and 20. Additionally, food and water were withheld from all the animals. On the following day, the rats were anesthetized and their albumin, aspartate aminotransferase (AST), alanine aminotransferase (ALT), alkaline phosphatase (ALP), serum glutamic oxaloacetic transaminase (SGOT), serum glutamic pyruvic transaminase (SGPT), gamma-glutamyl transpeptidase (GGT), lactate dehydrogenase (LDH), reactive oxygen species (ROS), methane dicarboxylic aldehyde (MDA), superoxide dismutase (SOD), catalase (CAT), and glutathione (GSH) levels were measured. Glutathione S-transferase (GST), glutathione reductase (GR), and glutathione peroxidase (GPx) levels among the groups were determined using a one-way analysis of variance.

RESULTS

The platelet count and blood platelet aggregation, blood platelet adhesion to fibrinogen and PF-4 secretion levels were significantly increased in the (3.5 g kg^-1 day^-1) AE group as compared to those in the control group (all p < 0.001; for the 7 and 14 g kg^-1 day^-1 AE groups, all p > 0.05, respectively). Although the PT and aPTT were not affected by the AE extract (all p > 0.05), the TT was reduced and the FIB levels were significantly increased in all AE groups (p < 0.05). Liver function tests showed that CCl₄ caused significant liver damage, thereby decreasing the albumin, SOD, CAT, GSH, GST, GR, and GPx levels, while increasing the AST, ALT, ALP, SGOT, SGPT, GGT, LDH, ROS, and MDA levels (all p < 0.001). By contrast, treatment with the different doses of AE extract reversed the CCl₄ effects on all these parameters. Compared with the levels in the CCl₄ group, the GSH and GR levels in the three AE groups (3.5, 7, and 14 g kg^-1·day^-1) were significantly higher (p < 0.05, p < 0.01, and p < 0.001, respectively), whereas the differences in the other parameters for these three groups were all at the significance levels of p < 0.05, p < 0.05, and p < 0.01, respectively.

CONCLUSIONS

AE extracts administered orally exhibited hepatoprotective activity by affecting platelet production and blood coagulation and ameliorating liver function-damaging modifications. Specifically, a dosage of 3.5 g kg^-1·day^-1 resulted in the most optimal effects.

Beneficial Effect of Edoxaban on Preventing Atrial Fibrillation and Coagulation by Reducing Inflammation via HBG1/HBD Biomarkers

Background: Atrial fibrillation (AF) is the most common cardiac arrhythmia. The effectiveness and mechanism of edoxaban in preventing stroke after atrial fibrillation remain unclear. Methods: The expressions of HBG1 and HBD in red blood cells were tested in AF. Sixty C57B/6J mice were randomly divided into the following groups: the control (CON) group, atrial fibrillation (AF) group, AF + edoxaban group, and AF + rivaroxaban group. H&E staining assay and reticular fiber staining were performed. Myocardial fibrosis was evaluated by the Masson staining assay, Sirius red staining assay, and immunohistochemical assay for the expressions of α-SMA and COL1A1. ELISA and RT-PCR assay were performed for the detection of inflammatory parameters (TNF-α, IL-1β, IL-6, and IL-10). Blood lipids were detected by using the Beckman automatic biochemical analyzer. Furthermore, four items of coagulation were detected, and molecular docking among HBG1, HBD, and MASP1 (Xa) was performed by PyMOL 2.1 software. The BP neural network model, cubic spline interpolation, and support vector machine model were constructed to predict prothrombin time based on HBG1 and HBD expressions. COIP assay was performed to construct the interaction between HBG1 and HBD. The functional enrichment analysis was performed by DAVID and Metascape tools. Results: The expressions of HBG1 and HBD in red blood cells of the patients with atrial fibrillation were decreased. The results showed a lower level of hemoglobin in red blood cells with HBG1-siRNA and HBG1-siRNA. Compared with the AF group, the collagen fiber percentage in the AF + edoxaban group was decreased (p < 0.05). After using edoxaban, the expressions of TNF-α, IL-1β, IL-6, and IL-10 were significantly decreased (p < 0.05). The LDL-C, TC, and TG levels were downregulated in the AF + edoxaban group. The PT and APTT levels in the AF + edoxaban group were more increasing than in the AF mice (p < 0.05). Compared with the AF group, the expressions of HBG1 and HBD were downregulated in the AF + edoxaban group (p < 0.05). HBG1 protein matched well with HBD and MASP1(Xa) protein surfaces. There exists a significant interaction between HBG1, HBD, and PT via the BP neural network and support vector machine. Enrichment analysis showed that HBG1 and HBD were mainly enriched in blood coagulation. Conclusion: Edoxaban could prevent atrial fibrillation and coagulation by reducing inflammation, lipids, and fibrosis via HBG1/HBD biomarkers effectively, and the effect was superior to that of rivaroxaban.

Effect of Thrombin on the Metabolism and Function of Murine Macrophages

Macrophages are plastic and heterogeneous immune cells that adapt pro- or anti-inflammatory phenotypes upon exposure to different stimuli. Even though there has been evidence supporting a crosstalk between coagulation and innate immunity, the way in which protein components of the hemostasis pathway influence macrophages remains unclear. We investigated the effect of thrombin on macrophage polarization. On the basis of gene expression and cytokine secretion, our results suggest that polarization with thrombin induces an anti-inflammatory, M2-like phenotype. In functional studies, thrombin polarization promoted oxLDL phagocytosis by macrophages, and conditioned medium from the same cells increased endothelial cell proliferation. There were, however, clear differences between the classical M2a polarization and the effects of thrombin on gene expression. Finally, the deletion and inactivation of secreted modular Ca²⁺-binding protein 1 (SMOC1) attenuated phagocytosis by thrombin-stimulated macrophages, a phenomenon revered by the addition of recombinant SMOC1. Manipulation of SMOC1 levels also had a pronounced impact on the expression of TGF-β-signaling-related genes. Taken together, our results show that thrombin induces an anti-inflammatory macrophage phenotype with similarities as well as differences to the classical alternatively activated M2 polarization states, highlighting the importance of tissue levels of SMOC1 in modifying thrombin-induced macrophage polarization.

Synthesis and Development of a Novel First-in-Class Cofilin Inhibitor for Neuroinflammation in Hemorrhagic Brain Injury

Intracerebral hemorrhage (ICH) is devastating among stroke types with high mortality. To date, not a single therapeutic intervention has been successful. Cofilin plays a critical role in inflammation and cell death. In the current study, we embarked on designing and synthesizing a first-in-class small-molecule inhibitor of cofilin to target secondary complications of ICH, mainly neuroinflammation. A series of compounds were synthesized, and two lead compounds SZ-3 and SK-1-32 were selected for further studies. Neuronal and microglial viabilities were assessed by 3-[4,5-dimethylthiazol-2-yl]-2,5-diphenyltetrazolium bromide (MTT) assay using neuroblastoma (SHSY-5Y) and human microglial (HMC-3) cell lines, respectively. Lipopolysaccharide (LPS)-induced inflammation in HMC-3 cells was used for neurotoxicity assay. Other assays include nitric oxide (NO) by Griess reagent, cofilin inhibition by F-actin depolymerization, migration by scratch wound assay, tumor necrosis factor (TNF-α) by enzyme-linked immunosorbent assay (ELISA), protease-activated receptor-1 (PAR-1) by immunocytochemistry and Western blotting (WB), and protein expression levels of several proteins by WB. SK-1-32 increased neuronal/microglial survival, reduced NO, and prevented neurotoxicity. However, SZ-3 showed no effect on neuronal/microglial survival but prevented microglia from LPS-induced inflammation by decreasing NO and preventing neurotoxicity. Therefore, we selected SZ-3 for further molecular studies, as it showed potent anti-inflammatory activities. SZ-3 decreased cofilin severing activity, and its treatment of LPS-activated HMC-3 cells attenuated microglial activation and suppressed migration and proliferation. HMC-3 cells subjected to thrombin, as an in vitro model for hemorrhagic stroke, and treated with SZ-3 after 3 h showed significantly decreased NO and TNF-α, significantly increased protein expression of phosphocofilin, and decreased PAR-1. In addition, SZ-3-treated SHSY-5Y showed a significant increase in cell viability by significantly reducing nuclear factor-κ B (NF-κB), caspase-3, and high-temperature requirement (HtrA2). Together, our results support the novel idea of targeting cofilin to counter neuroinflammation during secondary injury following ICH.

The RhoGEF Trio: A Protein with a Wide Range of Functions in the Vascular Endothelium

Many cellular processes are controlled by small GTPases, which can be activated by guanine nucleotide exchange factors (GEFs). The RhoGEF Trio contains two GEF domains that differentially activate the small GTPases such as Rac1/RhoG and RhoA. These small RhoGTPases are mainly involved in the remodeling of the actin cytoskeleton. In the endothelium, they regulate junctional stabilization and play a crucial role in angiogenesis and endothelial barrier integrity. Multiple extracellular signals originating from different vascular processes can influence the activity of Trio and thereby the regulation of the forementioned small GTPases and actin cytoskeleton. This review elucidates how various signals regulate Trio in a distinct manner, resulting in different functional outcomes that are crucial for endothelial cell function in response to inflammation.

Treatment with Edoxaban Attenuates Acute Stroke Severity in Mice by Reducing Blood-Brain Barrier Damage and Inflammation

Patients with atrial fibrillation and previous ischemic stroke (IS) are at increased risk of cerebrovascular events despite anticoagulation. In these patients, treatment with non-vitamin K oral anticoagulants (NOAC) such as edoxaban reduced the probability and severity of further IS without increasing the risk of major bleeding. However, the detailed protective mechanism of edoxaban has not yet been investigated in a model of ischemia/reperfusion injury. Therefore, in the current study we aimed to assess in a clinically relevant setting whether treatment with edoxaban attenuates stroke severity, and whether edoxaban has an impact on the local cerebral inflammatory response and blood–brain barrier (BBB) function after experimental IS in mice. Focal cerebral ischemia was induced by transient middle cerebral artery occlusion in male mice receiving edoxaban, phenprocoumon or vehicle. Infarct volumes, functional outcome and the occurrence of intracerebral hemorrhage were assessed. BBB damage and the extent of local inflammatory response were determined. Treatment with edoxaban significantly reduced infarct volumes and improved neurological outcome and BBB function on day 1 and attenuated brain tissue inflammation. In summary, our study provides evidence that edoxaban might exert its protective effect in human IS by modulating different key steps of IS pathophysiology, but further studies are warranted.

Secreted modular calcium-binding protein 1 binds and activates thrombin to account for platelet hyperreactivity in diabetes

Secreted modular calcium-binding protein 1 (SMOC1) is an osteonectin/SPARC-related matricellular protein, whose expression is regulated by microRNA-223 (miR-223). Given that platelets are rich in miR-223, this study investigated the expression of SMOC1 and its contribution to platelet function. Human and murine platelets expressed SMOC1, whereas platelets from SMOC1+/- mice did not present detectable mature SMOC1 protein. Platelets from SMOC1+/- mice demonstrated attenuated responsiveness to thrombin (platelet neutrophil aggregate formation, aggregation, clot formation, Ca2+ increase, and β3 integrin phosphorylation), whereas responses to other platelet agonists were unaffected. SMOC1 has been implicated in transforming growth factor-β signaling, but no link to this pathway was detected in platelets. Rather, the SMOC1 Kazal domain directly bound thrombin to potentiate its activity in vitro, as well as its actions on isolated platelets. The latter effects were prevented by monoclonal antibodies against SMOC1. Platelets from miR-223-deficient mice expressed high levels of SMOC1 and exhibited hyperreactivity to thrombin that was also reversed by preincubation with monoclonal antibodies against SMOC1. Similarly, SMOC1 levels were markedly upregulated in platelets from individuals with type 2 diabetes, and the SMOC1 antibody abrogated platelet hyperresponsiveness to thrombin. Taken together, we have identified SMOC1 as a novel thrombin-activating protein that makes a significant contribution to the pathophysiological changes in platelet function associated with type 2 diabetes. Thus, strategies that target SMOC1 or its interaction with thrombin may be attractive therapeutic approaches to normalize platelet function in diabetes.

Impact of sex differences on thrombin-induced hydrocephalus and white matter injury: the role of neutrophils

BACKGROUND

Thrombin has been implicated in playing a role in hydrocephalus development following intraventricular hemorrhage (IVH). However, the mechanisms underlying the sex differences to the detrimental effects of thrombin post-IVH remain elusive.

METHOD

Three-month old male and female Sprague-Dawley rats underwent unilateral intracerebroventricular (ICV) injections of 3U or 5U thrombin, or saline, to examine differences in thrombin-induced hydrocephalus and white matter injury. Mortality, and lateral ventricle volume and white matter injury were measured on magnetic resonance imaging evaluation at 24 h post-injection. In addition, male rats were pretreated with 17-β estradiol (E2, 5 mg/kg) or vehicle at 24 and 2 h prior to ICV injection of 3U thrombin. All rats were euthanized at 24 h post-injection for histology and immunohistochemistry.

RESULTS

ICV injection of 5U thrombin caused 100 and 0% mortality in female and male rats, respectively. 3U of thrombin resulted in significant ventricular dilation and white matter damage at 24 h in both male and female rats, but both were worse in females (p < 0.05). Furthermore, neutrophil infiltration into choroid plexus and periventricular white matter was enhanced in female rats and may play a critical role in the sex difference in brain injury. Pre-treating male rats with E2, increased thrombin (3U)-induced hydrocephalus, periventricular white matter injury and neutrophil infiltration into the choroid plexus and white matter.

CONCLUSIONS

ICV thrombin injection induced more severe ventricular dilation and white matter damage in female rats compared to males. Estrogen appears to contribute to this difference which may involve greater neutrophil infiltration in females. Understanding sex differences in thrombin-induced brain injury may shed light on future interventions for hemorrhagic stroke.

Gab2 (Grb2-Associated Binder2) Plays a Crucial Role in Inflammatory Signaling and Endothelial Dysfunction

[Figure: see text].

Photoelectrochemical aptasensing for thrombin based on exonuclease III-assisted recycling signal amplification and nanoceria enzymatic strategy

In the present work, a capture DNA (c-DNA) was immobilized on the TNA/g-C₃N₄ to develop a sensitive and selective TNA/g-C₃N₄/c-DNA photoelectrochemical aptasensor for determining thrombin. With the aid of the specific recognition of anti-thrombin aptamer towards thrombin, ingenious design of hairpin DNA, and exonuclease III-assisted recycling signal amplification, more nanoceria could be assembled on the TNA/g-C₃N₄/c-DNA to form TNA/g-C₃N₄/nanoceria in the presence of thrombin. Due to the oxidase-mimic catalytic efficiency of nanoceria and the oxygen consumption for glucose oxidation, the photoexcited electrons at the conduction band of g-C₃N₄ could be well transferred to that of TNA under visible light irradiation, resulting in the increase of the photocurrent of TNA/g-C₃N₄/nanoceria, and the increase value of photocurrent had a linear relationship with the concentration of thrombin under the optimal conditions. So, the constructed TNA/g-C₃N₄/c-DNA photoelectrochemical aptasensor exhibited a satisfactory quantitative range from 0.01 pM to 0.5 nM, low detection limit with 3.4 fM for thrombin determination, and was applied for the human serum analysis successfully with RSD of less than 4.8% and the recovery between 95% and 113%.

Thrombin Inhibition by Argatroban: Potential Therapeutic Benefits in COVID-19

Thrombin is a trypsin-like serine protease with multiple physiological functions. Its role in coagulation and thrombosis is well-established. Nevertheless, thrombin also plays a major role in inflammation by activating protease-activated receptors. In addition, thrombin is also involved in angiogenesis, fibrosis, and viral infections. Considering the pathogenesis of COVID-19 pandemic, thrombin inhibitors may exert multiple potential therapeutic benefits including antithrombotic, anti-inflammatory, and antiviral activities. In this review, we describe the clinical features of COVID-19, the thrombin’s roles in various pathologies, and the potential of argatroban in COVID-19 patients. Argatroban is a synthetic, small molecule, direct, competitive, and selective inhibitor of thrombin. It is approved to parenterally prevent and/or treat heparin-induced thrombocytopenia in addition to other thrombotic conditions. Argatroban also possesses anti-inflammatory and antiviral activities and has a well-established pharmacokinetics profile. It also appears to lack a significant risk of drug–drug interactions with therapeutics currently being evaluated for COVID-19. Thus, argatroban presents a substantial promise in treating severe cases of COVID-19; however, this promise is yet to be established in randomized, controlled clinical trials.

Factor Xa and thrombin induce endothelial progenitor cell activation. The effect of direct oral anticoagulants

Factor Xa (FXa) and thrombin exert non-hemostatic cellular actions primarily mediated through protease-activated receptors (PARs). We investigated the effect of FXa and thrombin on human late-outgrowth endothelial cells (OECs), a type of endothelial progenitor cells (EPCs), and on human umbilical vein endothelial cells (HUVECs). The effect of direct oral anticoagulants (DOACs), rivaroxaban and dabigatran, was also studied. The membrane expression of intercellular adhesion molecule-1 (ICAM-1) and the secretion of monocyte chemoattractant protein-1 (MCP-1) were used as cell activation markers. FXa and thrombin increase the ICAM-1 expression and the MCP-1 secretion on both cells, being higher on OECs. Vorapaxar, a specific PAR-1 antagonist, completely inhibits FXa-induced activation of both cells and thrombin-induced HUVEC activation, but only partially thrombin-induced OEC activation. Furthermore, thrombin-receptor activating peptide; TRAP-6, only partially activates OECs. OECs do not membrane-express PAR-4, therefore it may not be involved on thrombin-induced OEC activation. Rivaroxaban and dabigatran inhibit OEC and HUVEC activation by FXa and thrombin, respectively. Rivaroxaban enhances thrombin-induced OEC and HUVEC activation, which is completely inhibited by vorapaxar. The inhibition of OEC and HUVEC activation by vorapaxar and DOACs may represent a new pleiotropic effect of these drugs. The pathophysiological and clinical significance of our findings need to be established.

Hirudin Protects Against Kidney Damage in Streptozotocin-Induced Diabetic Nephropathy Rats by Inhibiting Inflammation via P38 MAPK/NF-κB Pathway

Background

Inflammation-induced podocyte apoptosis plays an important role in kidney injury during diabetic nephropathy (DN). Hirudin (HIR), a natural compound extracted from leeches, can inhibit inflammation. However, whether HIR can protect the kidneys against inflammation during DN is unknown. In the present study, we aimed to study the effects of HIR on kidney damage in a DN rat model and explore its anti-inflammatory properties.

Methods

A streptozotocin-induced DN rat model was generated, and HIR was administered subcutaneously. Immortal podocytes and primary peritoneal macrophages were used for vitro studies. Hematoxylin and eosin staining was used to evaluate renal pathological changes; quantitative polymerase chain reaction and immunoblotting were used to detect gene expression; and TUNEL staining was used to detect apoptotic cells.

Results

Our results showed that HIR protected against renal injury, as indicated by kidney weight/body weight, serum creatinine, renal pathological changes, blood urea nitrogen, and detection of urine proteins. Notably, HIR treatment reduced macrophage infiltration, pro-inflammatory cytokine expression, and podocyte apoptosis in the kidney tissues of DN rats. In vitro, high glucose (HG) induced the activation of M1 macrophages, which was accompanied by increased podocyte apoptosis. HIR could decrease HG-induced podocyte apoptosis and suppress pro-inflammatory cytokine expression in podocytes in vitro. This was achieved via inhibition of p38 MAPK/NF-κB activation in renal tissues and podocytes.

Conclusion

HIR could inhibit inflammation via the p38 MAPK/NF-κB pathway, prevent podocyte apoptosis, and protect against kidney damage in a DN rat model.

Acute exacerbations of COPD are associated with a prothrombotic state through platelet-monocyte complexes, endothelial activation and increased thrombin generation

INTRODUCTION

Patients with chronic obstructive pulmonary disease (COPD) are at increased risk for cardiovascular events, particularly following an acute exacerbation (AE-COPD). Exacerbations are associated with increased systemic inflammation, which may drive coagulation. This prospective cohort study aimed to determine how an AE-COPD affects platelet activation, the endothelium, plasmatic coagulation and fibrinolysis, and its association with systemic inflammation.

MATERIALS AND METHODS

Fifty-two patients with an AE-COPD were included. Blood samples at admission, at day 3 of treatment and at convalescence were available for 32 patients. Platelet-monocyte complex (PMC) formation, monocyte Mac-1 expression and platelet (re)activity (P-selectin expression, αIIbβ3 activation) were measured by flow cytometry. Von Willebrand Factor (VWF), thrombin generation (TG) and clot lysis time (CLT) were determined as measures of endothelial activation, plasmatic coagulation and fibrinolysis, respectively.

RESULTS

Exacerbations were associated with increased PMCs (MFI 31.3 vs 23.8, p = 0.004) and Mac-1 (MFI 38.2 vs 34.8, p = 0.006) compared to convalescence, but not with changes in platelet (re)activity. VWF (antigen, activity, active fraction) and TG (peak, ETP and velocity index) were all significantly higher during AE-COPD compared to convalescence. PMCs, Mac-1, VWF and TG were positively associated with systemic inflammation (CRP). CLT was prolonged in AE-COPD patients with systemic inflammation. Moreover, platelet hyperreactivity on admission was associated with an increased risk for exacerbation relapse.

CONCLUSIONS

Acute exacerbations are associated with an inflammation-associated prothrombotic state, characterized by increased PMCs, endothelial activation and plasmatic coagulation. Our findings provide direction for future studies on biomarkers predicting the risk of exacerbation relapse and cardiovascular events.

Phosphoproteomic analysis of protease-activated receptor-1 biased signaling reveals unique modulators of endothelial barrier function

Thrombin, a procoagulant protease, cleaves and activates protease-activated receptor-1 (PAR1) to promote inflammatory responses and endothelial dysfunction. In contrast, activated protein C (APC), an anticoagulant protease, activates PAR1 through a distinct cleavage site and promotes anti-inflammatory responses, prosurvival, and endothelial barrier stabilization. The distinct tethered ligands formed through cleavage of PAR1 by thrombin versus APC result in unique active receptor conformations that bias PAR1 signaling. Despite progress in understanding PAR1 biased signaling, the proteins and pathways utilized by thrombin versus APC signaling to induce opposing cellular functions are largely unknown. Here, we report the global phosphoproteome induced by thrombin and APC signaling in endothelial cells with the quantification of 11,266 unique phosphopeptides using multiplexed quantitative mass spectrometry. Our results reveal unique dynamic phosphoproteome profiles of thrombin and APC signaling, an enrichment of associated biological functions, including key modulators of endothelial barrier function, regulators of gene transcription, and specific kinases predicted to mediate PAR1 biased signaling. Using small interfering RNA to deplete a subset of phosphorylated proteins not previously linked to thrombin or APC signaling, a function for afadin and adducin-1 actin binding proteins in thrombin-induced endothelial barrier disruption is unveiled. Afadin depletion resulted in enhanced thrombin-promoted barrier permeability, whereas adducin-1 depletion completely ablated thrombin-induced barrier disruption without compromising p38 signaling. However, loss of adducin-1 blocked APC-induced Akt signaling. These studies define distinct thrombin and APC dynamic signaling profiles and a rich array of proteins and biological pathways that engender PAR1 biased signaling in endothelial cells.

Thrombin as Key Mediator of Seizure Development Following Traumatic Brain Injury

Traumatic brain injury (TBI) commonly leads to development of seizures, accounting for approximately 20% of newly diagnosed epilepsy. Despite the high clinical significance, the mechanisms underlying the development of posttraumatic seizures (PTS) remain unclear, compromising appropriate management of these patients. Accumulating evidence suggest that thrombin, the main serine protease of the coagulation cascade, is involved in PTS genesis by mediating inflammation and hyperexcitability following blood brain barrier breakdown. In order to further understand the role of thrombin in PTS, we generated a combined mild TBI (mTBI) and status epilepticus mice model, by injecting pilocarpine to mice previously submitted to head injury. Interestingly, mTBI was able to reduce seizure onset in the pilocarpine animal model as well as increase the death rate in the treated animals. In turn, pilocarpine worsened spatial orientation of mTBI treated mice. Finally, thrombin activity as well as the expression of IL1-β and TNF-α was significantly increased in the mTBI-pilocarpine treated animals. In conclusion, these observations indicate a synergism between thrombin and mTBI in lowering seizure in the pilocarpine model and possibly aggravating inflammation. We believe that these results will improve the understanding of PTS pathophysiology and contribute to the development of more targeted therapies in the future.

Endothelial Cell Calcium Signaling during Barrier Function and Inflammation

Calcium is an essential second messenger in endothelial cells and plays a pivotal role in regulating a number of physiologic processes, including cell migration, angiogenesis, barrier function, and inflammation. An increase in intracellular Ca²⁺ concentration can trigger a number of diverse signaling pathways under both physiologic and pathologic conditions. In this review, we discuss how calcium signaling pathways in endothelial cells play an essential role in affecting barrier function and facilitating inflammation. Inflammatory mediators, such as thrombin and histamine, increase intracellular calcium levels. This calcium influx causes adherens junction disassembly and cytoskeletal rearrangements to facilitate endothelial cell retraction and increased permeability. During inflammation endothelial cell calcium entry and the calcium-related signaling events also help facilitate several leukocyte-endothelial cell interactions, such as leukocyte rolling, adhesion, and ultimately transendothelial migration.

2-Arylidene-1-indandiones as Pleiotropic Agents with Antioxidant and Inhibitory Enzymes Activities

Indandiones are a relatively new group of compounds presenting a wide range of biological activities. The synthesis of these compounds was performed via a Knoevenagel reaction between an aldehyde and 1,3-indandione and were obtained with a yield up to 54%. IR, 1H-Nucleic Magnetic Resonance (NMR), 13C-NMR, LC/MS ESI+ and elemental analysis were used for the confirmation of the structures of the novel derivatives. Lipophilicity values of compounds were calculated theoretically and experimentally by reversed chromatography method as values RM. The novel derivatives were studied through in vitro and in vivo experiments for their activity as anti-inflammatory and antioxidant agents and as inhibitors of lipoxygenase, trypsin, and thrombin. The inhibition of the carrageenin-induced paw edema (CPE) was also determined for representative structures. In the above series of experiments, we find that all the compounds showed moderate to satisfying interaction with the stable DPPH free radical in relation to the concentration and the time 2-arylidene-1-indandione (10) was the strongest. We observed moderate or very low antioxidant activities for selected compounds in the decolorization assay with ABTS+•. Most of the compounds showed high anti-lipid peroxidation of linoleic acid induced by AAPH.2-arylidene-1-indandione (7) showed a strongly inhibited soybean LOX. Only 2-arylidene-1-indandione (3) showed moderate scavenging activity of superoxide anion, whereas 2-arylidene-1-indandione (8) and 2-arylidene-1-indandione (9) showed very strong inhibition on proteolysis. 2-arylidene-1-indandione (8) highly inhibited serine protease thrombin. 2-arylidene-1-indandiones (7, 8 and 9) can be used as lead multifunctional molecules. The compounds were active for the inhibition of the CPE (30-57%) with 2-arylidene-1-indandione (1) being the most potent (57%). According to the predicted results a great number of the derivatives can cross the Blood-Brain Barrier (BBB), act in CNS and easily transported, diffused, and absorbed. Efforts are conducted a) to correlate quantitatively the in vitro/in vivo results with the most important physicochemical properties of the structural components of the molecules and b) to clarify the correlation of actions among them to propose a possible mechanism of action. Hydration energy as EHYDR and highest occupied molecular orbital (HOMO) better describe their antioxidant profile whereas the lipophilicity as RM values governs the in vivo anti-inflammatory activity. Docking studies are performed and showed that soybean LOX oxidation was prevented by blocking into the hydrophobic domain the substrates to the active site.

Regulation of endothelial barrier integrity by redox-dependent nitric oxide signaling: Implication in traumatic and inflammatory brain injuries

Nitric oxide (NO) synthesized by eNOS plays a key role in regulation of endothelial barrier integrity but underlying cell signaling pathway is not fully understood at present. Here, we report opposing roles of two different redox-dependent NO metabolites; peroxynitrite (ONOO-) vs. S-nitrosoglutathione (GSNO), in cell signaling pathways for endothelial barrier disruption. In cultured human brain microvessel endothelial cells (hBMVECs), thrombin induced F-actin stress fiber formation causes barrier disruption via activating eNOS. Thrombin induced eNOS activity participated in cell signaling (e.g. RhoA and calcium influx mediated phosphorylation of myosin light chain) for F-actin stress fiber formation by increasing ONOO- levels. On the other hand, thrombin had no effect on intracellular levels of S-nitrosoglutathione (GSNO), another cellular NO metabolite. However, exogenous GSNO treatment attenuated the thrombin-induced cell signaling pathways for endothelial barrier disruption, thus suggesting the role of a shift of NO metabolism (GSNO vs. ONOO-) toward ONOO- synthesis in cell signaling for endothelial barrier disruption. Consistent with these in vitro studies, in animal models of traumatic brain injury and experimental autoimmune encephalomyelitis (EAE), ONOO- scavenger treatment as well as GSNO treatment were effective for attenuation of BBB leakage, edema formation, and CNS infiltration of mononuclear cells. Taken together, these data document that eNOS-mediated NO production and following redox-dependent NO metabolites (ONOO- vs. GSNO) are potential therapeutic target for CNS microvascular disease (traumatic and inflammatory) pathologies.

A chemiluminescence aptasensor for thrombin detection based on aptamer-conjugated and hemin/G-quadruplex DNAzyme signal-amplified carbon fiber composite

In this work, a highly sensitive and selective chemiluminescence (CL) aptasensor was prepared for thrombin (THR) detection based on aptamer-conjugated and hemin/G-quadruplex DNAzyme signal-amplified carbon fiber composite (HG-DNAzyme/T-Apt/SiO₂@GO@CF). Initially, SiO₂@GO@CF was successfully prepared and characterized by Scanning Electron Microscopy (SEM), X-ray Diffraction (XRD) and Fourier Transform Infrared Spectroscopy (FT-IR). Thrombin aptamer (T-Apt) as an identification element and simulated enzyme - hemin/G-quadruplex DNAzyme (HG-DNAzyme) as a signal-amplified material, were applied in the CL aptasensor. Then, the immobilization properties of SiO₂@GO@CF and adsorption properties of T-Apt/SiO₂@GO@CF were studied. Lastly, HG-DNAzyme/T-Apt/SiO₂@GO@CF was applied in construction of the CL aptasensor. When THR existed, HG-DNAzyme was desorbed from the surface of T-Apt/SiO₂@GO@CF and catalyzed the CL system of luminol-H₂O₂. Under optimized CL conditions, THR was measured with the linear concentration range of 1.5 × 10^-14 to 2.5 × 10^-11 moL/L and the detection limit of 6.3 × 10^-15 moL/L (3δ). The proposed CL aptasensor was used to the determination of THR in human serum samples and recoveries ranged from 99.0% to 102.4%. Those satisfactory results illustrated the CL aptasensor could achieve highly sensitive and selective detection of THR and revealed potential application in practical samples.

Heparin as a molecular spacer immobilized on microspheres to improve blood compatibility in hemoperfusion

Heparin, a highly sulfated linear polysaccharide, with anticoagulation function and blood compatibility is widely used as a biomaterials in medical application, but the most importance of heparin is its structure function as the macromolecular space arm. In this study, heparin as a spacer was covalently immobilized on the chloromethylated polystyrene microspheres (Ps) and then connected with l-phenylalanine forming the Ps-Hep-Phe structure, which was developed for endotoxin adsorption in hemoperfusion. The grafting density of heparin reach the maximum when the initial concentration of heparin solution was 5 mg/mL. The adsorbents with the heparin as a spacer showed the prolonged clotting times, low protein adsorption, and reduced the hemolysis rate, indicating that heparin-modified adsorbents have great blood compatibility. The adsorption capacity of Ps-Hep-Phe for endotoxin was 25.15 EU/g in dynamic adsorption, higher than that of Ps. Therefore, this study imply that heparin would be promising for modification of adsorbents in hemoperfusion.

Antiinflammatory effects of aspirin in ACS: relevant to its cardio coronary actions?

Vascular injury in acute coronary syndromes (ACS) involves a complex cross-talk between inflammatory mediators, platelets and thrombosis, where the interaction between platelets and coagulation factors (e. g. thrombin) is a central link between thrombosis and inflammation. In ACS, aspirin at antiplatelet doses exhibits anti-inflammatory effects as seen from the decrease in inflammation markers such as CRP, M-CSF, MCP-1 and others. These actions probably occur subsequent to inhibition of platelet COX-1-dependent thromboxane formation and its action as a multipotent autocrine and paracrine agent. This likely involves inhibition of thrombin formation as well as inhibition of secondary pro-inflammatory mediators, such as sphingosine-1-phosphate. Experimental and limited clinical data additionally suggest antiinflammatory effects of aspirin independent of its antiplatelet action. For example, aspirin at antiplatelet doses might acetylate COX-2 in vascular cells, directing the activity of the enzyme into a 15-lipoxygenase which by transcellular metabolism results in the formation of 15-epi-lipoxin (‘aspirin-triggered lipoxin’), an antiinflammatory mediator. Furthermore, aspirin stimulates eNOS via lysine-acetylation, eventually resulting in induction of heme oxygenase (HO-1), which improves the antioxidative potential of vascular cells. All of these effects have been seen at antiplatelet doses of 100–300 mg/day, equivalent to peak plasma levels of 10–30 μM. Many more potentially antiinflammatory mechanisms of aspirin have been described, mostly salicy-late-related, at low to medium millimolar concentrations and, therefore, are of minor clinical interest. Altogether, there is a wealth of data supporting antiiflammatory effects of aspirin in ACS, but studies generating direct evidence for antiinflammatory effects in ACS remain to be done.

The Role of Gap Junction-Mediated Endothelial Cell-Cell Interaction in the Crosstalk between Inflammation and Blood Coagulation

Endothelial cells (ECs) play a pivotal role in the crosstalk between blood coagulation and inflammation. Endothelial cellular dysfunction underlies the development of vascular inflammatory diseases. Recent studies have revealed that aberrant gap junctions (GJs) and connexin (Cx) hemichannels participate in the progression of cardiovascular diseases such as cardiac infarction, hypertension and atherosclerosis. ECs can communicate with adjacent ECs, vascular smooth muscle cells, leukocytes and platelets via GJs and Cx channels. ECs dynamically regulate the expression of numerous Cxs, as well as GJ functionality, in the context of inflammation. Alterations to either result in various side effects across a wide range of vascular functions. Here, we review the roles of endothelial GJs and Cx channels in vascular inflammation, blood coagulation and leukocyte adhesion. In addition, we discuss the relevant molecular mechanisms that endothelial GJs and Cx channels regulate, both the endothelial functions and mechanical properties of ECs. A better understanding of these processes promises the possibility of pharmacological treatments for vascular pathogenesis.

Highly sensitive protein detection via covalently linked aptamer to MoS2 and exonuclease-assisted amplification strategy

Molybdenum disulfide (MoS2) has shown highly attractive superiority as a platform for sensing. However, DNA physisorption on the surface of MoS2 was susceptible to nonspecific probe displacement and false-positive signals. To solve these problems, we have developed a novel MoS2-aptamer nanosheet biosensor for detecting thrombin using a covalently linked aptamer to the MoS2 nanosheet. Ten percent Tween 80 was used to prevent thrombin from nonspecific binding and to rapidly form thiol-DNA/gold nanoparticle (AuNP) conjugates. Furthermore, an MoS2 and exonuclease coassisted signal amplification strategy was developed to improve the detection limit for thrombin. We used the hybridization of the aptamer molecules and the matched strand with a 5' terminal thiol to immobilize the aptamer molecules on the surface of AuNPs in AuNPs@MoS2 nanocomposites. Exonuclease digested the single-strand aptamer and released the thrombin, which was then detected in the next recycle. With the coassisted amplification strategy, a 6 fM detection limit was achieved, showing that this method has higher sensitivity than most reported methods for thrombin detection. The results presented in this work show that this method of covalently attaching the aptamer and using the coassisted amplification is a promising technique for the detection of protein in medical diagnostics.

Targeting activated protein C to treat hemophilia

PURPOSE OF REVIEW

Hemophilia is a debilitating disease, marked by frequent, painful bleeding events, joint deterioration and early death. All current treatments consist of i.v. infusions of replacement factor or other procoagulant factors, and are incompletely effective, due in part to the short half-lives of the proteins. An alternative approach is to rebalance hemostasis by inhibiting natural anticoagulant mechanisms. In this article, we explain why activated protein C (APC) is an appropriate and safe target for the treatment of hemophilia.

RECENT FINDINGS

A serpin (serine protease inhibitor) was engineered to specifically inhibit APC and was found to rescue hemostasis in a hemophilia mouse model, even after a severe tail clip injury. However, APC is also anti-inflammatory and has cytoprotective activities, raising safety concerns over the use of an APC inhibitor to treat hemophilia. We summarize the molecular basis of the anticoagulant and signaling activities of APC to assess the potential impact of targeting APC.

SUMMARY

We conclude that the signaling and anticoagulant functions of APC are in spatially and kinetically distinct compartments, and that it is possible to specifically inhibit the anticoagulant activity of APC. Targeting APC with a serpin is remarkably effective and may be safe for long-term prophylactic use in the treatment of hemophilia.

Thrombin Cleavage of Inter-α-inhibitor Heavy Chain 1 Regulates Leukocyte Binding to an Inflammatory Hyaluronan Matrix

Dynamic alterations of the extracellular matrix in response to injury directly modulate inflammation and consequently the promotion and resolution of disease. During inflammation, hyaluronan (HA) is increased at sites of inflammation where it may be covalently modified with the heavy chains (HC) of inter-α-trypsin inhibitor. Deposition of this unique, pathological form of HA (HC-HA) leads to the formation of cable-like structures that promote adhesion of leukocytes. Naive mononuclear leukocytes bind specifically to inflammation-associated HA matrices but do not adhere to HA constitutively expressed under homeostatic conditions. In this study, we have directly investigated a role for the blood-coagulation protease thrombin in regulating the adhesion of monocytic cells to smooth muscle cells producing an inflammatory matrix. Our data demonstrate that the proteolytic activity of thrombin negatively regulates the adhesion of monocytes to an inflammatory HC-HA complex. This effect is independent of protease-activated receptor activation but requires proteolytic activity toward a novel substrate. Components of HC-HA complexes were predicted to contain conserved thrombin-susceptible cleavage sites based on sequence analysis, and heavy chain 1 (HC1) was confirmed to be a substrate of thrombin. Thrombin treatment is sufficient to cleave HC1 associated with either cell-surface HA or serum inter-α-trypsin inhibitor. Furthermore, thrombin treatment of the inflammatory matrix leads to dissolution of HC-HA cable structures and abolishes leukocyte adhesion. These data establish a novel mechanism whereby thrombin cleavage of HC1 regulates the adhesive properties of an inflammatory HA matrix.

Protein determination using graphene oxide-aptamer modified gold nanoparticles in combination with Tween 80

Recently, graphene oxide (GO) has shown superiority for disease detection arising from its unique physical and chemical properties. However, proteins adsorbed on the surface of GO prevent sensitivity improvement in fluorescence-based detection methods. In this paper, a label-free method based on aptamer modified gold nanoparticles (GNPs) combined with Tween 80 was shown to solve this problem using the detection of thrombin as an example. An aptamer was designed and bound to thrombin by changing its conformation. Tween 80 was used for rapid and reproducible synthesis of stable DNA-functionalized GNPs and prevented the thrombin from nonspecific binding to GO. Thrombin was detected with a limit of 0.68 pM by taking advantage of the efficient cross-linking effect of aptamer-GNPs to GO. The sensor was validated by determining thrombin concentration in human blood serum samples. The results indicate that this method has promising analytical application in medical diagnostic.

CCN1/CYR61-mediated meticulous patrolling by Ly6Clow monocytes fuels vascular inflammation

Inflammation is characterized by the recruitment of leukocytes from the bloodstream. The rapid arrival of neutrophils is followed by a wave of inflammatory lymphocyte antigen 6 complex (Ly6C)-positive monocytes. In contrast Ly6C(low) monocytes survey the endothelium in the steady state, but their role in inflammation is still unclear. Here, using confocal intravital microscopy, we show that upon Toll-like receptor 7/8 (TLR7/8)-mediated inflammation of mesenteric veins, platelet activation drives the rapid mobilization of Ly6C(low) monocytes to the luminal side of the endothelium. After repeatedly interacting with platelets, Ly6C(low) monocytes commit to a meticulous patrolling of the endothelial wall and orchestrate the subsequent arrival and extravasation of neutrophils through the production of proinflammatory cytokines and chemokines. At a molecular level, we show that cysteine-rich protein 61 (CYR61)/CYR61 connective tissue growth factor nephroblastoma overexpressed 1 (CCN1) protein is released by activated platelets and enables the recruitment of Ly6C(low) monocytes upon vascular inflammation. In addition endothelium-bound CCN1 sustains the adequate patrolling of Ly6C(low) monocytes both in the steady state and under inflammatory conditions. Blocking CCN1 or platelets with specific antibodies impaired the early arrival of Ly6C(low) monocytes and abolished the recruitment of neutrophils. These results refine the leukocyte recruitment cascade model by introducing endothelium-bound CCN1 as an inflammation mediator and by demonstrating a role for platelets and patrolling Ly6C(low) monocytes in acute vascular inflammation.