The cytoprotective protein C pathway

Heme-induced loss of renovascular endothelial protein C receptor promotes chronic kidney disease in sickle mice

ABSTRACT

Chronic kidney disease (CKD) is a major contributor to morbidity and mortality in sickle cell disease (SCD). Anemia, induced by chronic persistent hemolysis, is associated with the progressive deterioration of renal health, resulting in CKD. Moreover, patients with SCD experience acute kidney injury (AKI), a risk factor for CKD, often during vaso-occlusive crisis associated with acute intravascular hemolysis. However, the mechanisms of hemolysis-driven pathogenesis of the AKI-to-CKD transition in SCD remain elusive. Here, we investigated the role of increased renovascular rarefaction and the resulting substantial loss of the vascular endothelial protein C receptor (EPCR) in the progressive deterioration of renal function in transgenic SCD mice. Multiple hemolytic events raised circulating levels of soluble EPCR (sEPCR), indicating loss of EPCR from the cell surface. Using bone marrow transplantation and super-resolution ultrasound imaging, we demonstrated that SCD mice overexpressing EPCR were protective against heme-induced CKD development. In a cohort of patients with SCD, plasma sEPCR was significantly higher in individuals with CKD than in those without CKD. This study concludes that multiple hemolytic events may trigger CKD in SCD through the gradual loss of renovascular EPCR. Thus, the restoration of EPCR may be a therapeutic target, and plasma sEPCR can be developed as a prognostic marker for sickle CKD.

Met343Val mutation disrupts the shuttling of Trp380 leading to a low-activity conformer of activated protein C and causes thrombosis

BACKGROUND

Protein C (PC) pathway serves as a major defense mechanism against thrombosis by the activation of PC through the thrombin-thrombomodulin complex and subsequent inactivation of the activated factor (F)V (FVa) and FVIII (FVIIIa) with the assistance of protein S, thereby contributing to hemostatic balance. We identified 2 unrelated patients who suffered from recurrent thrombosis and carried the same heterozygous mutation c.1153A>G, p.Met343Val (M343V), in PROC gene. This mutation had not been previously reported.

OBJECTIVES

To explore the molecular basis underlying the anticoagulant defect in patients carrying the M343V mutation in PROC.

METHODS

We expressed PC-M343V variant in mammalian cells and characterized its properties through coagulation assays.

RESULTS

Our findings demonstrated that while activation of mutant zymogen by thrombin-thrombomodulin complex was slightly affected, cleavage of chromogenic substrate by APC-M343V was significantly impaired. However, Ca2+ increased the cleavage efficiency by approximately 50%. Additionally, there was a severe reduction in affinity between APC-M343V and Na+. Furthermore, the inhibitory ability of APC-M343V toward FVa was markedly impaired. Structural and simulation analyses suggested that Val343 might disrupt the potential hydrogen bonds with Trp380 and cause Trp380 to orient closer to His211, potentially interfering with substrate binding and destabilizing the catalytic triad of APC.

CONCLUSION

The M343V mutation in patients adversely affects the reactivity and/or folding of the active site as well as the binding of the physiological substrate to the protease, resulting in impaired protein C anticoagulant activity and ultimately leading to thrombosis.

Novel Targets and Potential Mechanisms of Mizuhopecten yessoensis-Derived Tripeptide NCW as Antihypertensive Peptides

SCOPE

Mizuhopecten yessoensis-derived tripeptide Asn-Cys-Trp (NCW) exhibits a potent antihypertensive effect in vivo. However, a lack of knowledge of the antihypertensive mechanism of tripeptide NCW limits its application for functional foods industrialization. The purpose of this study is to elucidate the corresponding targets and mechanisms of tripeptide NCW in hypertension regulation.

METHODS AND RESULTS

Administration of tripeptide NCW for 3 weeks, the blood pressure of spontaneously hypertensive rats (SHRs) is significantly decreased. After sacrifice, the serum sample is analyzed using tandem mass tag (TMT)-based liquid chromatography with tandem mass spectrometry to identify differentially expressed proteins. The proteomic analysis indicates that tripeptide NCW administration alters serum protein profiles in SHR rats, significantly upregulating 106 proteins and downregulating 30 proteins. These proteins enhance the glycolysis, glucose, and TCA cycle, improve amino metabolism, trigger the cAMP/PKA, cGMP/PKG, PI3K/AKT, and AMPK signal pathways, and inhibit Ras-regulated JNK activation, TGF-β/MAPK, and TGF-β/ RhoA/ROCK pathways.

CONCLUSION

Tripeptide NCW supplementation is demonstrated to regulate signal pathways involved in the control of blood pressure and regulate the energy and amino acids metabolic processes in serum, providing important insights into the protective effects of tripeptide NCW on hypertension.

Selecting potential biomarkers of plasma proteins in mares with endometritis

BACKGROUND

Endometritis is a common condition in mares that causes significant economic loss. Lacking obvious clinical signs, the clinical diagnosis of endometritis in mares relies on case-by-case clinical examinations, which can be particularly inefficient in large-scale farms. Therefore, the identification of potential biomarkers can serve as a non-invasive and efficient screening technique for endometritis in mares.

OBJECTIVES

To compare the blood proteome between fertile mares and mares with endometritis to identify biomarkers potentially associated with the development of endometritis and validate their predictive potential.

STUDY DESIGN

Observational and experimental study.

METHODS

Differentially expressed proteins were identified via Data Independent Acquisition (DIA) proteomic profiling in a screening cohort composed of eight healthy mares and eight mares with endometritis. Subsequently, enzyme-linked immunosorbent assay was employed that included a validation cohort of 40 healthy mares and 40 mares with endometritis to verify the accuracy and sensitivity of the identified proteins, thereby establishing a diagnostic threshold.

RESULTS

In the screening cohort, 12 proteins were significantly differentially expressed between endometritis mares and healthy controls (p < 0.05, outside the 1/1.2 to 1.2-fold). In the validation experiment, all six screened proteins were assessed with area under the curve (AUC) >0.8.

MAIN LIMITATIONS

The samples displayed certain levels of individual heterogeneity, and the number of samples analysed was limited. Additionally, the identified biomarkers were primarily associated with generalised inflammation, which potentially limited their specificity for endometritis.

CONCLUSION

Levels of plasma proteins are sensitive indicators of equine endometritis and potential tools for endometritis screening. In plasma, fetuin B, von Willebrand factor, vitamin K-dependent protein C, insulin-like growth factor binding protein 3, interleukin 1 receptor accessory protein, and type II cell cytoskeleton showed great predictive ability, with fetuin B being the best predictor (AUC = 0.93, 95% CI: 0.89-0.98), which performs better when combined with all six detected proteins (AUC = 1, 95% CI: 0.99-1.00).

Coagulation and Inflammation in COVID-19: Reciprocal Relationship between Inflammatory and Coagulation Markers

The coronavirus disease 2019 (COVID-19) is caused by severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2), formerly known as 2019-nCoV. Numerous cellular and biochemical issues arise after COVID-19 infection. The severe inflammation that is caused by a number of cytokines appears to be one of the key hallmarks of COVID-19. Additionally, people with severe COVID-19 have coagulopathy and fulminant thrombotic events. We briefly reviewed the COVID-19 disease at the beginning of this paper. The inflammation and coagulation markers and their alterations in COVID-19 illness are briefly discussed in the parts that follow. Next, we talked about NETosis, which is a crucial relationship between coagulation and inflammation. In the end, we mentioned the two-way relationship between inflammation and coagulation, as well as the factors involved in it. We suggest that inflammation and coagulation are integrated systems in COVID-19 that act on each other in such a way that not only inflammation can activate coagulation but also coagulation can activate inflammation.

Ser252Asn Mutation Introduces a New N-Linked Glycosylation Site and Causes Type IIb Protein C Deficiency

BACKGROUND

 Protein C (PC) is a vitamin K-dependent anticoagulant serine protease zymogen which upon activation by the thrombin-thrombomodulin (TM) complex downregulates the coagulation cascade by degrading cofactors Va and VIIIa by limited proteolysis. We identified a thrombosis patient who carried a heterozygous mutation c.881G > A, p.Ser252Asn (S252N) in PROC. This mutation was originally described in a report of novel mutations in patients presenting with defective PC anticoagulant activity in Paris. The research identified PC-S252N (the "Paris" mutation) in a propositus and her family members and highlighted the critical role of Ser252 in the anticoagulation process of activated PC (APC).

MATERIAL AND METHODS

 We expressed the PC-S252N mutant in mammalian cells and characterized the properties in coagulation assays to decipher the molecular basis of anticoagulant defect of this mutation.

RESULTS

 We demonstrated that PC-S252N had a diminished ability to TM binding, which resulted in its impaired activation by the thrombin-TM complex. However, APC-S252N exhibited a slightly stronger cleavage capacity for the chromogenic substrate. Meanwhile, the catalytic activity of APC-S252N toward FVa was significantly reduced. Sequence analysis revealed that Ser252 to Asn substitution introduced a new potential N-linked glycosylation site (252NTT254) in the catalytic domain of PC, which adversely affected both the activation process of PC and anticoagulant activity of APC.

CONCLUSION

 The new N-glycosylation site (252NTT254) resulting from the mutation of Ser252 to Asn252 in PROC affects the overall structure of the protease, thereby adversely affecting the anticoagulant function of protein C. This modification has a negative impact on both TM-promoted activation of protein C and APC cleavage of FVa, ultimately leading to thrombosis in the patient.

Coagulation Protease-Driven Cancer Immune Evasion: Potential Targets for Cancer Immunotherapy

Blood coagulation and cancer are intrinsically connected, hypercoagulation-associated thrombotic complications are commonly observed in certain types of cancer, often leading to decreased survival in cancer patients. Apart from the common role in coagulation, coagulation proteases often trigger intracellular signaling in various cancers via the activation of a G protein-coupled receptor superfamily protease: protease-activated receptors (PARs). Although the role of PARs is well-established in the development and progression of certain types of cancer, their impact on cancer immune response is only just emerging. The present review highlights how coagulation protease-driven PAR signaling plays a key role in modulating innate and adaptive immune responses. This is followed by a detailed discussion on the contribution of coagulation protease-induced signaling in cancer immune evasion, thereby supporting the growth and development of certain tumors. A special section of the review demonstrates the role of coagulation proteases, thrombin, factor VIIa, and factor Xa in cancer immune evasion. Targeting coagulation protease-induced signaling might be a potential therapeutic strategy to boost the immune surveillance mechanism of a host fighting against cancer, thereby augmenting the clinical consequences of targeted immunotherapeutic regimens.

A potential mechanism for the cytoprotective effects of activated protein C-released endothelial extracellular vesicles

ABSTRACT

Activated protein C (APC) was shown to release extracellular vesicles (EVs). APC bound to the EVs was thought to be responsible for cytoprotection. Our study demonstrates that the cytoprotective effects of APC-released EVs are independent of APC. APC-released EVs carry anti-inflammatory microRNAs in their cargo.

Challenges in the Management of Large Burns

Large burns provoke profound pathophysiological changes. Survival rates of patients with large burns have improved significantly with the advancement of critical care and adaptation of early excision protocols. Nevertheless, care of large burn wounds remains challenging secondary to limited donor sites, prolonged time to wound closure, and immunosuppression. The development of skin substitutes and new grafting techniques decreased time to wound closure. Individually, these methods have limited success, but a combination of them may yield more successful outcomes. Early identification of patients with likely poor prognosis should prompt goals of care discussion and involvement of a palliative care team when possible.

Endothelial Protein C Receptor and Its Impact on Rheumatic Disease

Endothelial Protein C Receptor (EPCR) is a key regulator of the activated protein C anti-coagulation pathway due to its role in the binding and activation of this protein. EPCR also binds to other ligands such as Factor VII and X, γδ T-cells, plasmodium falciparum erythrocyte membrane protein 1, and Secretory group V Phospholipases A2, facilitating ligand-specific functions. The functions of EPCR can also be regulated by soluble (s)EPCR that competes for the binding sites of membrane-bound (m)EPCR. sEPCR is created when mEPCR is shed from the cell surface. The propensity of shedding alters depending on the genetic haplotype of the EPCR gene that an individual may possess. EPCR plays an active role in normal homeostasis, anti-coagulation pathways, inflammation, and cell stemness. Due to these properties, EPCR is considered a potential effector/mediator of inflammatory diseases. Rheumatic diseases such as rheumatoid arthritis and systemic lupus erythematosus are autoimmune/inflammatory conditions that are associated with elevated EPCR levels and disease activity, potentially driven by EPCR. This review highlights the functions of EPCR and its contribution to rheumatic diseases.

Inter- and Intra-donor variability in bone marrow-derived mesenchymal stromal cells: implications for clinical applications

BACKGROUND AIMS

Mesenchymal stromal cells (MSCs) are attractive as a therapeutic modality in multiple disease conditions characterized by inflammation and vascular compromise. Logistically they are advantageous because they can be isolated from adult tissue sources, such as bone marrow (BM). The phase 2a START clinical trial determined BM-MSCs to be safe in patients with moderate-to-severe acute respiratory distress syndrome (ARDS). Herein, we examine a subset of the clinical doses of MSCs generated for the phase 2a START trial from three unique donors (1-3), where one of the donors' donated BM on two separate occasions (donor 3 and 3W).

METHODS

The main objective of this study was to correlate properties of the cells from the four lots with plasma biomarkers from treated patients and relevant to ARDS outcomes. To do this we evaluated MSC donor lots for (i) post-thaw viability, (ii) growth kinetics, (iii) metabolism, (iv) surface marker expression, (v) protein expression, (vi) immunomodulatory ability and (vii) their functional effects on regulating endothelial cell permeability.

RESULTS

MSC-specific marker expression and protection of thrombin-challenged endothelial barrier permeability was similar among all four donor lots. Inter and intra-donor variability was observed in all the other in vitro assays. Furthermore, patient plasma ANG-2 and protein C levels at 6 hours post-transfusion were correlated to cell viability in an inter- and intra-donor dependent manner.

CONCLUSIONS

These findings highlight the potential of donor dependent (inter-) and collection dependent (intra-) effects in patient biomarker expression.

Thrombomodulin Switches Signaling and Protease-Activated Receptor 1 Cleavage Specificity of Thrombin

BACKGROUND

Cleavage of the extracellular domain of PAR1 (protease-activated receptor 1) by thrombin at Arg41 and by APC (activated protein C) at Arg46 initiates paradoxical cytopathic and cytoprotective signaling in endothelial cells. In the latter case, the ligand-dependent coreceptor signaling by EPCR (endothelial protein C receptor) is required for the protective PAR1 signaling by APC. Here, we investigated the role of thrombomodulin in determining the specificity of PAR1 signaling by thrombin.

METHODS

We prepared a PAR1 knockout (PAR1-/-) EA.hy926 endothelial cell line by CRISPR/Cas9 and transduced PAR1-/- cells with lentivirus vectors expressing PAR1 mutants in which either Arg41 or Arg46 was replaced with an Ala. Furthermore, human embryonic kidney 293 cells were transfected with wild-type or mutant PAR1 cleavage reporter constructs carrying N-terminal Nluc (NanoLuc luciferase) and C-terminal enhanced yellow fluorescent protein tags.

RESULTS

Characterization of transfected cells in signaling and receptor cleavage assays revealed that, upon interaction with thrombomodulin, thrombin cleaves Arg46 to elicit cytoprotective effects by a β-arrestin-2 biased signaling mechanism. Analysis of functional data and cleavage rates indicated that thrombin-thrombomodulin cleaves Arg46>10-fold faster than APC. Upon interaction with thrombin, the cytoplasmic domain of thrombomodulin recruited both β-arrestin-1 and -2 to the plasma membrane. Thus, the thrombin cleavage of Arg41 was also cytoprotective in thrombomodulin-expressing cells by β-arrestin-1-biased signaling. APC in the absence of EPCR cleaved Arg41 to initiate disruptive signaling responses like thrombin.

CONCLUSIONS

These results suggest that coreceptor signaling by thrombomodulin and EPCR determines the PAR1 cleavage and signaling specificity of thrombin and APC, respectively.

Cellular and Noncellular Approaches for Repairing the Damaged Blood-CNS-Barrier in Amyotrophic Lateral Sclerosis

Numerous reports have demonstrated the breakdown of the blood-CNS barrier (B-CNS-B) in amyotrophic lateral sclerosis (ALS), a fatal neurodegenerative disease. Re-establishing barrier integrity in the CNS is critical to prevent further motor neuron degeneration from harmful components in systemic circulation. Potential therapeutic strategies for repairing the B-CNS-B may be achieved by the replacement of damaged endothelial cells (ECs) via stem cell administration or enhancement of endogenous EC survival through the delivery of bioactive particles secreted by stem cells. These cellular and noncellular approaches are thoroughly discussed in the present review. Specific attention is given to certain stem cell types for EC replacement. Also, various nanoparticles secreted by stem cells as well as other biomolecules are elucidated as promising agents for endogenous EC repair. Although the noted in vitro and in vivo studies show the feasibility of the proposed therapeutic approaches to the repair of the B-CNS-B in ALS, further investigation is needed prior to clinical transition.

Managing Temporomandibular Joint Ankylosis Concurrent With Extrahepatic Portal Vein Obstruction: A Report of a Rare Case and Literature Review Investigating the Hypercoagulability Link

This report describes the understudied co-occurrence of temporomandibular joint ankylosis (TMJA) and extrahepatic portal vein obstruction (EHPVO), exploring a shared pathway involving hypercoagulability. TMJA is an acquired pathology where joint surfaces fuse, causing restricted mouth opening and facial asymmetry. Globally, TMJA is prevalent among 1.5 to 5 patients/million, with a higher incidence in developing countries. While trauma and infections often cause TMJA, the pathogenesis remains unclear in many cases. Recent literature notes a link between TMJA and EHPVO, a noncirrhotic vascular disorder causing portal hypertension and upper gastrointestinal bleeding in children. Prothrombotic disorders such as protein C and S deficiency may contribute to EHPVO, mirroring TMJA's association with hypercoagulability. This report focuses on an 11-year-old female diagnosed with TMJA, accompanied by a history of ear infection and concurrent EHPVO. We further presented clinical observations, surgical interventions, and outcomes alongside a literature review to understand the probable connection between EHPVO and TMJA.

Neuroprotective Effects of Noncanonical PAR1 Agonists on Cultured Neurons in Excitotoxicity

Serine proteases regulate cell functions through G protein-coupled protease-activated receptors (PARs). Cleavage of one peptide bond of the receptor amino terminus results in the formation of a new N-terminus ("tethered ligand") that can specifically interact with the second extracellular loop of the PAR receptor and activate it. Activation of PAR1 by thrombin (canonical agonist) and activated protein C (APC, noncanonical agonist) was described as a biased agonism. Here, we have supposed that synthetic peptide analogs to the PAR1 tethered ligand liberated by APC could have neuroprotective effects like APC. To verify this hypothesis, a model of the ischemic brain impairment based on glutamate (Glu) excitotoxicity in primary neuronal cultures of neonatal rats has been used. It was shown that the nanopeptide NPNDKYEPF-NH2 (AP9) effectively reduced the neuronal death induced by Glu. The influence of AP9 on cell survival was comparable to that of APC. Both APC and AP9 reduced the dysregulation of intracellular calcium homeostasis in cultured neurons induced by excitotoxic Glu (100 µM) or NMDA (200 µM) concentrations. PAR1 agonist synthetic peptides might be noncanonical PAR1 agonists and a basis for novel neuroprotective drugs for disorders related to Glu excitotoxicity such as brain ischemia, trauma and some neurodegenerative diseases.

Mitigation of trauma-induced endotheliopathy by activated protein C: A potential therapeutic for postinjury thromboinflammation

BACKGROUND

Activated Protein C (aPC) plays dual roles after injury, driving both trauma-induced coagulopathy (TIC) by cleaving, and thus inactivating, factors Va and VIIIa and depressing fibrinolysis while also mediating an inflammomodulatory milieu via protease activated receptor-1 (PAR-1) cytoprotective signaling. Because of this dual role, it represents and ideal target for study and therapeutics after trauma. A known aPC variant, 3K3A-aPC, has been engineered to preserve cytoprotective activity while retaining minimal anticoagulant activity rendering it potentially ideal as a cytoprotective therapeutic after trauma. We hypothesized that 3K3A-aPC would mitigate the endotheliopathy of trauma by protecting against endothelial permeability.

METHODS

We used electric cell-substrate impedance sensing to measure permeability changes in real time in primary endothelial cells. These were cultured, grown to confluence, and treated with a 2 μg/mL solution of 3K3A-aPC at 180 minutes, 120 minutes, 60 minutes, 30 minutes prior to stimulation with ex vivo plasma taken from severely injured trauma patients (Injury Severity Score > 15 and BD < -6) (trauma plasma [TP]). Cells treated with thrombin and untreated cells were included in this study as control groups. Permeability changes were recorded in real time via electric cell-substrate impedance sensing for 30 minutes after treatment with TP. We quantified permeability changes in the control and treatment groups as area under the curve (AUC). Rac1/RhoA activity was also compared between these groups. Statistical significance was determined by one-way ANOVA followed by a post hoc analysis using Tukey's multiple comparison's test.

RESULTS

Treatment with aPC mitigated endothelial permeability induced by ex vivo trauma plasma at all pre-treatment time points. The AUC of the 30-minute 3K3A-aPC pretreatment group was higher than TP alone (mean diff. 22.12 95% CI [13.75, 30.49], p < 0.0001) (Figure). Moreover, the AUC of the 60-minute, 120-minute, and 180-minute pretreatment groups was also higher than TP alone (mean diff., 16.30; 95% confidence interval [CI], 7.93-24.67; 19.43; 95% CI, 11.06-27.80, and 18.65; 95% CI, 10.28-27.02;, all p < 0.0001, respectively). Rac1/RhoA activity was higher in the aPC pretreatment group when compared with all other groups ( p < 0.01).

CONCLUSION

Pretreatment with 3K3A-aPC, which retains its cytoprotective function but has only ~5% of its anticoagulant function, abrogates the effects of trauma-induced endotheliopathy. This represents a potential therapeutic treatment for dysregulated thromboinflammation for injured patients by minimizing aPC's role in trauma-induced coagulopathy while concurrently amplifying its essential cytoprotective function.

LEVEL OF EVIDENCE

Prognostic and Epidemiological; Level III.

Post-Translational Oxidative Modifications of Hemostasis Proteins: Structure, Function, and Regulation

Reactive oxygen species (ROS) are constantly generated in a living organism. An imbalance between the amount of generated reactive species in the body and their destruction leads to the development of oxidative stress. Proteins are extremely vulnerable targets for ROS molecules, which can cause oxidative modifications of amino acid residues, thus altering structure and function of intra- and extracellular proteins. The current review considers the effect of oxidation on the structural rearrangements and functional activity of hemostasis proteins: coagulation system proteins such as fibrinogen, prothrombin/thrombin, factor VII/VIIa; anticoagulant proteins - thrombomodulin and protein C; proteins of the fibrinolytic system such as plasminogen, tissue plasminogen activator and plasminogen activator inhibitor-1. Structure and function of the proteins, oxidative modifications, and their detrimental consequences resulting from the induced oxidation or oxidative stress in vivo are described. Possible effects of oxidative modifications of proteins in vitro and in vivo leading to disruption of the coagulation and fibrinolysis processes are summarized and systematized, and the possibility of a compensatory mechanism in maintaining hemostasis under oxidative stress is analyzed.

A recombinant signalling-selective activated protein C that lacks anticoagulant activity is efficacious and safe in cutaneous wound preclinical models

Various preclinical and clinical studies have demonstrated the robust wound healing capacity of the natural anticoagulant activated protein C (APC). A bioengineered APC variant designated 3K3A-APC retains APC's cytoprotective cell signalling actions with <10% anticoagulant activity. This study was aimed to provide preclinical evidence that 3K3A-APC is efficacious and safe as a wound healing agent. 3K3A-APC, like wild-type APC, demonstrated positive effects on proliferation of human skin cells (keratinocytes, endothelial cells and fibroblasts). Similarly it also increased matrix metollaproteinase-2 activation in keratinocytes and fibroblasts. Topical 3K3A-APC treatment at 10 or 30 μg both accelerated mouse wound healing when culled on Day 11. And at 10 μg, it was superior to APC and had half the dermal wound gape compared to control. Further testing was conducted in excisional porcine wounds due to their congruence to human skin. Here, 3K3A-APC advanced macroscopic healing in a dose-dependent manner (100, 250 and 500 μg) when culled on Day 21. This was histologically corroborated by greater collagen maturity, suggesting more advanced remodelling. A non-interference arm of this study found no evidence that topical 3K3A-APC caused either any significant systemic side-effects or any significant leakage into the circulation. However the female pigs exhibited transient and mild local reactions after treatments in week three, which did not impact healing. Overall these preclinical studies support the hypothesis that 3K3A-APC merits future human wound studies.

Involvement of PAR-2 in the Induction of Cell-Specific Matrix Metalloproteinase-2 by Activated Protein C in Cutaneous Wound Healing

We previously reported that human keratinocytes express protease-activated receptor (PAR)-2 and play an important role in activated protein C (APC)-induced cutaneous wound healing. This study investigated the involvement of PAR-2 in the production of gelatinolytic matrix metalloproteinases (MMP)-2 and -9 by APC during cutaneous wound healing. Full-thickness excisional wounds were made on the dorsum of male C57BL/6 mice. Wounds were treated with APC on days 1, 2, and 3 post-wounding. Cultured neonatal foreskin keratinocytes were treated with APC with or without intact PAR-2 signalling to examine the effects on MMP-2 and MMP-9 production. Murine dermal fibroblasts from PAR-2 knock-out (KO) mice were also assessed. MMP-2 and -9 were measured via gelatin zymography, fluorometric assay, and immunohistochemistry. APC accelerated wound healing in WT mice, but had a negligible effect in PAR-2 KO mice. APC-stimulated murine cutaneous wound healing was associated with the differential and temporal production of MMP-2 and MMP-9, with the latter peaking on day 1 and the former on day 6. Inhibition of PAR-2 in human keratinocytes reduced APC-induced MMP-2 activity by 25~50%, but had little effect on MMP-9. Similarly, APC-induced MMP-2 activation was reduced by 40% in cultured dermal fibroblasts derived from PAR-2 KO mice. This study shows for the first time that PAR-2 is essential for APC-induced MMP-2 production. Considering the important role of MMP-2 in wound healing, this work helps explain the underlying mechanisms of action of APC to promote wound healing through PAR-2.

Recent advances in the role of neutrophils and neutrophil extracellular traps in acute pancreatitis

Pancreatitis is an inflammatory disease, which is triggered by adverse events in acinar cells of the pancreas. After the initial injury, infiltration of neutrophils in pancreas is observed. In the initial stages of pancreatitis, the inflammation is sterile. It has been shown that the presence of neutrophils at the injury site can modulate the disease. Their depletion in experimental animal models of the acute pancreatitis has been shown to be protective. But information on mechanism of contribution to inflammation by neutrophils at the injury site is not clear. Once at injury site, activated neutrophils release azurophilic granules containing proteolytic enzymes and generate hypochlorous acid which is a strong microbicidal agent. Additionally, emerging evidence shows that neutrophil extracellular traps (NETs) are formed which consist of decondensed DNA decorated with histones, proteases and granular and cytosolic proteins. NETs are considered mechanical traps for microbes, but there is preliminary evidence to indicate that NETs, which constitute a special mechanism of the neutrophil defence system, play an adverse role in pancreatitis by contributing to the pancreatic inflammation and distant organ injury. This review presents the overall current information about neutrophils and their role including NETs in acute pancreatitis (AP). It also highlights current gaps in knowledge which should be explored to fully elucidate the role of neutrophils in AP and for therapeutic gains.

Design and characterization of novel activated protein C variants for the proteolysis of cytotoxic extracellular histone H3

BACKGROUND

Extracellular histone H3 is implicated in several pathologies including inflammation, cell death, and organ failure. Neutralization of histone H3 is a strategy that was shown beneficial in various diseases, such as rheumatoid arthritis, myocardial infarction, and sepsis. It was shown that activated protein C (APC) can cleave histone H3, which reduces histone cytotoxicity. However, due to the anticoagulant properties of APC, the use of APC is not optimal for the treatment of histone-mediated cytotoxicity, in view of its associated bleeding side effects.

OBJECTIVES

This study aimed to investigate the detailed molecular interactions between human APC and human histone H3, and subsequently use molecular docking and molecular dynamics simulation methods to identify key interacting residues that mediate the interaction between APC and histone H3 and to generate novel optimized APC variants.

METHODS

After molecular simulations, the designed APC variants 3D2D-APC (Lys37-39Asp and Lys62-63Asp) and 3D2D2A-APC (Lys37-39Asp, Lys62-63Asp, and Arg74-75Ala) were recombinantly expressed and their abilities to function as anticoagulant, to bind histones, and to cleave histones were tested and correlated with their cytoprotective properties.

RESULTS

Compared with wild type-APC, both the 3D2D-APC and 3D2D2A-APC variants showed a significantly decreased anticoagulant activity, increased binding to histone H3, and similar ability to proteolyze histone H3.

CONCLUSIONS

Our data show that it is possible to rationally design APC variants that may be further developed into therapeutic biologicals to treat histone-mediated disease, by proteolytic reduction of histone-associated cytotoxic properties that do not induce an increased bleeding risk.

Atherosclerosis in Patients with Congenital Hemophilia: A Focus on Peripheral Artery Disease

Advances in the treatment of hemophilia have increased the life expectancy of this population and we are currently facing diseases associated with aging, including cardiovascular ones. Coronary atherosclerosis, with acute myocardial infarction as the most severe form of manifestation, has been recognized as part of the comorbidities of hemophiliacs. However, little is known about peripheral artery disease. Available data show that hemophiliacs have cardiovascular risk factors and atherosclerosis similar to the general population. Impaired thrombus formation and phenotype of atheroma plaque rather than the burden of atherosclerosis explains their lower cardiovascular mortality. Since the effect of traditional cardiovascular risk factors overpowers that of decreased coagulability and promotes the onset and progression of atherosclerotic lesions, screening for traditional cardiovascular risk factors and peripheral artery disease should be integrated into standard hemophilia care. There is evidence that invasive treatments and long-term antithrombotic therapy are generally safe, provided that coagulation factor levels are taken into account and replacement therapy is given when necessary.

Mechanisms regulating heterogeneity of hemostatic gene expression in endothelial cells

The hemostatic system involves an array of circulating coagulation factors that work in concert with platelets and the vascular endothelium to promote clotting in a space- and time-defined manner. Despite equal systemic exposure to circulating factors, bleeding and thrombotic diseases tend to prefer specific sites, suggesting an important role for local factors. This may be provided by endothelial heterogeneity. Endothelial cells differ not only between arteries, veins, and capillaries but also between microvascular beds from different organs, which present unique organotypic morphology and functional and molecular profiles. Accordingly, regulators of hemostasis are not uniformly distributed in the vasculature. The establishment and maintenance of endothelial diversity are orchestrated at the transcriptional level. Recent transcriptomic and epigenomic studies have provided a global picture of endothelial cell heterogeneity. In this review, we discuss the organotypic differences in the hemostatic profile of endothelial cells; we focus on 2 major endothelial regulators of hemostasis, namely von Willebrand factor and thrombomodulin, to provide examples of transcriptional mechanisms that control heterogeneity; finally, we consider some of the methodological challenges and opportunities for future studies.

Association between acute complications in PMM2-CDG patients and haemostasis anomalies: Data from a multicentric study and suggestions for acute management

OBJECTIVES

Patients with PMM2-CDG develop acute events (stroke-like episodes (SLEs), thromboses, haemorrhages, seizures, migraines) associated with both clotting factors (factor XI) and coagulation inhibitors (antithrombin, protein C and protein S) deficiencies. The aim of the study was to correlate acute events to haemostasis and propose practical guidelines.

METHODS

In this multicentric retrospective study, we evaluated clinical, radiological, haemostasis and electroencephalography data for PMM2-CDG patients hospitalized for acute events. Cerebral events were classified as thrombosis, haemorrhage, SLE, or "stroke mimic" (SM: normal brain imaging or evoking a migraine).

RESULTS

Thirteen patients had a total of 31 acute episodes: 27 cerebral events with 7 SLEs, 4 venous thromboses, 4 haemorrhages (3 associated with thrombosis), 15 SMs at a mean age of 7.7 years; 4 non-cerebral thromboses, one of which included bleeding. A trigger was frequently involved (infection, head trauma). Although sometimes normal at baseline state, factor XI, antithrombin and protein C levels decreased during these episodes. No correlation between haemostasis anomalies and type of acute event was found.

DISCUSSION

Acute events in PMM2-CDG are not negligible and are associated with haemostasis anomalies. An emergency protocol is proposed for their prevention and treatment (https://www.filiere-g2m.fr/urgences). For cerebral events, brain Magnetic Resonance Imaging with perfusion weight imaging and diffusion sequences, electroencephalogram and haemostasis protein levels guide the treatment: anticoagulation, antithrombin or fresh frozen plasma supplementation, antiepileptic therapy. Preventing bleeding and thrombosis is required in cases of surgery, prolonged immobilization, hormone replacement therapy.

CONCLUSION

Acute events in PMM2-CDG are associated with abnormal haemostasis, requiring practical guidance.

Activated protein C in epilepsy pathophysiology

Epilepsy is one of the most common neurologic disorders that is characterized by recurrent seizures, and depending on the type of seizure, it could lead to a severe outcome. Epilepsy's mechanism of development is not fully understood yet, but some of the common features of the disease are blood-brain barrier disruption, microglia activation, and neuroinflammation. Those are also targets of activated protein C (APC). In fact, by downregulating thrombin, known as a pro-inflammatory, APC acts as an anti-inflammatory. APC is also an anti-apoptotic protein, instance by blocking p53-mediated apoptosis. APC's neuroprotective effect could prevent blood-brain barrier dysfunction by acting on endothelial cells. Furthermore, through the downregulation of proapoptotic, and proinflammatory genes, APC's neuroprotection could reduce the effect or prevent epilepsy pathogenesis. APC's activity acts on blood-brain barrier disruption, inflammation, and apoptosis and causes neurogenesis, all hallmarks that could potentially treat or prevent epilepsy. Here we review both Activated Protein C and epilepsy mechanism, function, and the possible association between them.

A spatially specified systems pharmacology therapy for axonal recovery after injury

There are no known drugs or drug combinations that promote substantial central nervous system axonal regeneration after injury. We used systems pharmacology approaches to model pathways underlying axonal growth and identify a four-drug combination that regulates multiple subcellular processes in the cell body and axons using the optic nerve crush model in rats. We intravitreally injected agonists HU-210 (cannabinoid receptor-1) and IL-6 (interleukin 6 receptor) to stimulate retinal ganglion cells for axonal growth. We applied, in gel foam at the site of nerve injury, Taxol to stabilize growing microtubules, and activated protein C to clear the debris field since computational models predicted that this drug combination regulating two subcellular processes at the growth cone produces synergistic growth. Physiologically, drug treatment restored or preserved pattern electroretinograms and some of the animals had detectable visual evoked potentials in the brain and behavioral optokinetic responses. Morphology experiments show that the four-drug combination protects axons or promotes axonal regrowth to the optic chiasm and beyond. We conclude that spatially targeted drug treatment is therapeutically relevant and can restore limited functional recovery.

Circulating Soluble EPCR Levels Are Reduced in Patients with Ischemic Peripheral Artery Disease and Associated with Markers of Endothelial and Vascular Function

(1) Background: Endothelial dysfunction initiates cardiovascular pathologies, including peripheral artery disease (PAD). The pathophysiology of impaired new vessel formation in the presence of angiogenic stimuli, such as ischemia and inflammation, is unknown. We have recently shown in mice that reduced endothelial protein C receptor (EPCR) expression results in defective angiogenesis following experimental hindlimb ischemia. (2) Purpose: To determine soluble (s)EPCR levels in the plasma of patients with PAD and to compare them with the protein C activity and biomarkers of endothelial function, inflammation, and angiogenesis. (3) Methods and Results: Clinical tests of vascular function and immunoassays of plasma from patients with PAD stage II were compared to age- and sex-matched individuals with and without cardiovascular risk factors or PAD stage III/IV patients. sEPCR levels were significantly lower in PAD stage II patients compared to subjects with risk factors, but no PAD, and further decreased in PAD stage III/IV patients. Plasma protein C activity or levels of ADAM17, a mediator of EPCR shedding, did not differ. Significant associations between sEPCR and the ankle-brachial index (p = 0.0359), age (p = 0.0488), body mass index (p = 0.0110), and plasma sE-selectin levels (p = 0.0327) were observed. High-sensitive CRP levels and white blood cell counts were significantly elevated in PAD patients and associated with serum glucose levels, but not sEPCR. In contrast, plasma TNFα or IL1β levels did not differ. Circulating levels of VEGF were significantly elevated in PAD stage II patients (p = 0.0198), but not associated with molecular (sE-selectin) or functional (ankle-brachial index) markers of vascular health. (4) Conclusions: Our findings suggest that circulating sEPCR levels may be useful as biomarkers of endothelial dysfunction, including angiogenesis, in persons older than 35 years and that progressive loss of endothelial protein C receptors might be involved in the development and progression of PAD.

Endothelial APC/PAR1 distinctly regulates cytokine-induced pro-inflammatory VCAM-1 expression

Introduction: Dysfunction of the endothelium impairs its' protective role and promotes inflammation and progression of vascular diseases. Activated Protein C (APC) elicits endothelial cytoprotective responses including barrier stabilization, anti-inflammatory and anti-apoptotic responses through the activation of the G protein-coupled receptor (GPCR) protease-activated receptor-1 (PAR1) and is a promising therapeutic. Despite recent advancements in developing new Activated protein C variants with clinical potential, the mechanism by which APC/PAR1 promotes different cytoprotective responses remains unclear and is important to understand to advance Activated protein C and new targets as future therapeutics. Here we examined the mechanisms by which APC/PAR1 attenuates cytokine-induced pro-inflammatory vascular cell adhesion molecule (VCAM-1) expression, a key mediator of endothelial inflammatory responses. Methods: Quantitative multiplexed mass spectrometry analysis of Activated protein C treated endothelial cells, endothelial cell transcriptomics database (EndoDB) online repository queries, biochemical measurements of protein expression, quantitative real-time polymerase chain reaction (RT-qPCR) measurement of mRNA transcript abundance, pharmacological inhibitors and siRNA transfections of human cultured endothelial cells. Results: Here we report that Activated Protein C modulates phosphorylation of tumor necrosis factor (TNF)-α signaling pathway components and attenuates of TNF-α induced VCAM-1 expression independent of mRNA stability. Unexpectedly, we found a critical role for the G protein-coupled receptor co-receptor sphingosine-1 phosphate receptor-1 (S1PR1) and the G protein receptor kinase-2 (GRK2) in mediating APC/PAR1 anti-inflammatory responses in endothelial cells. Discussion: This study provides new knowledge of the mechanisms by which different APC/PAR1 cytoprotective responses are mediated through discrete β-arrestin-2-driven signaling pathways modulated by specific G protein-coupled receptor co-receptors and GRKs.

Effect of INR on Outcomes of Endovascular Treatment for Acute Vertebrobasilar Artery Occlusion

Endovascular treatment (EVT) has been proven to be the standard treatment for acute vertebrobasilar artery occlusion (VBAO). This study aimed to analyze the effects of international normalized ratio (INR) indicators on outcomes in patients with acute VBAO treated with EVT. Dynamic data on INR in patients with VBAO who received endovascular treatment (EVT) at 65 stroke centers in China were retrospectively enrolled. Outcome measures included the modified Rankin Scale (mRS) score at 90 days and 1 year and symptomatic intracranial hemorrhage (sICH). The associations between elevated INR (INR > 1.1), INR variability (time-weighted variance of INR changes), and various clinical outcomes were analyzed in all patients and subgroups stratified by oral anticoagulation (OAC) by mixed logistic regression analysis. A total of 1825 patients met the study criteria, of which 1384 had normal INR and 441 had elevated INR. Multivariate analysis showed that elevated INR was significantly associated with poor functional outcomes (mRS 4-6) at 90 days (odds ratio [OR] 1.36, 95% confidence interval [CI] 1.08-1.72) and 1 year (OR 1.32, 95% CI 1.05-1.66), but was not associated with an increased risk of sICH (OR 1.00, 95% CI 0.83-1.20). Similar associations exist between INR variability and poor functional outcomes at 90 days (OR 2.17, 95% CI 1.09-4.30), 1 year (OR 2.28, 95% CI 1.16-4.46), and sICH (OR 1.11, 95% CI 0.93-1.33). Subgroup analyses further revealed that elevated INR and INR variability remained associated with poor functional outcomes in patients not receiving oral anticoagulation (OAC) therapy, while no significant associations were observed in OAC-treated patients, regardless of whether they were on warfarin or direct oral anticoagulants. Elevated INR and INR variability in VBAO patients treated with EVT were associated with poor functional outcomes. The mechanism underlying the association between elevated INR and poor functional outcomes might be attributed to the fact that elevated INR indirectly reflects the burden of comorbidities, which could independently worsen outcomes. These findings underscore the importance of a comprehensive and dynamic evaluation of INR levels in the management of VBAO patients receiving EVT, providing valuable insights for optimizing patient outcomes.

E-WE thrombin, a protein C activator, reduces disease severity and spinal cord inflammation in relapsing-remitting murine experimental autoimmune encephalomyelitis

Objective

Relapses in patients with relapsing-remitting multiple sclerosis (RRMS) are typically treated with high-dose corticosteroids including methylprednisolone. However, high-dose corticosteroids are associated with significant adverse effects, can increase the risk for other morbidities, and often do not impact disease course. Multiple mechanisms are proposed to contribute to acute relapses in RRMS patients, including neuroinflammation, fibrin formation and compromised blood vessel barrier function. The protein C activator, E-WE thrombin is a recombinant therapeutic in clinical development for its antithrombotic and cytoprotective properties, including protection of endothelial cell barrier function. In mice, treatment with E-WE thrombin reduced neuroinflammation and extracellular fibrin formation in myelin oligodendrocyte glycoprotein (MOG)-induced experimental autoimmune encephalomyelitis (EAE). We therefore tested the hypothesis that E-WE thrombin could reduce disease severity in a relapsing-remitting model of EAE.

Methods

Female SJL mice were inoculated with proteolipid protein (PLP) peptide and treated with E-WE thrombin (25 μg/kg; iv) or vehicle at onset of detectable disease. In other experiments, E-WE thrombin was compared to methylprednisolone (100 mg/kg; iv) or the combination of both.

Results

Compared to vehicle, administration of E-WE thrombin significantly improved disease severity of the initial attack and relapse and delayed onset of relapse as effectively as methylprednisolone. Both methylprednisolone and E-WE thrombin reduced demyelination and immune cell recruitment, and the combination of both treatments had an additive effect.

Conclusion

The data presented herein demonstrate that E-WE thrombin is protective in mice with relapsing-remitting EAE, a widely used model of MS. Our data indicate that E-WE thrombin is as effective as high-dose methylprednisolone in improving disease score and may exert additional benefit when administered in combination. Taken together, these data suggest that E-WE thrombin may be an effective alternative to high-dose methylprednisolone for managing acute MS attacks.

Severe Trauma-Induced Coagulopathy: Molecular Mechanisms Underlying Critical Illness

Trauma remains one of the leading causes of death in adults despite the implementation of preventive measures and innovations in trauma systems. The etiology of coagulopathy in trauma patients is multifactorial and related to the kind of injury and nature of resuscitation. Trauma-induced coagulopathy (TIC) is a biochemical response involving dysregulated coagulation, altered fibrinolysis, systemic endothelial dysfunction, platelet dysfunction, and inflammatory responses due to trauma. The aim of this review is to report the pathophysiology, early diagnosis and treatment of TIC. A literature search was performed using different databases to identify relevant studies in indexed scientific journals. We reviewed the main pathophysiological mechanisms involved in the early development of TIC. Diagnostic methods have also been reported which allow early targeted therapy with pharmaceutical hemostatic agents such as TEG-based goal-directed resuscitation and fibrinolysis management. TIC is a result of a complex interaction between different pathophysiological processes. New evidence in the field of trauma immunology can, in part, help explain the intricacy of the processes that occur after trauma. However, although our knowledge of TIC has grown, improving outcomes for trauma patients, many questions still need to be answered by ongoing studies.

Platelet glycoprotein V spatio-temporally controls fibrin formation

The activation of platelets and coagulation at vascular injury sites is crucial for haemostasis but can promote thrombosis and inflammation in vascular pathologies. Here, we delineate an unexpected spatio-temporal control mechanism of thrombin activity that is platelet orchestrated and locally limits excessive fibrin formation after initial haemostatic platelet deposition. During platelet activation, the abundant platelet glycoprotein (GP) V is cleaved by thrombin. We demonstrate with genetic and pharmacological approaches that thrombin-mediated shedding of GPV does not primarily regulate platelet activation in thrombus formation, but rather has a distinct function after platelet deposition and specifically limits thrombin-dependent generation of fibrin, a crucial mediator of vascular thrombo-inflammation. Genetic or pharmacologic defects in haemostatic platelet function are unexpectedly attenuated by specific blockade of GPV shedding, indicating that the spatio-temporal control of thrombin-dependent fibrin generation also represents a potential therapeutic target to improve haemostasis.

Activated protein C inhibits mesothelial-to-mesenchymal transition in experimental peritoneal fibrosis

BACKGROUND

In addition to its anticoagulant function in downregulating thrombin generation, activated protein C (APC) evokes pleiotropic cytoprotective signaling activities when it binds to endothelial protein C receptor (EPCR) to activate protease-activated receptor 1 (PAR1) in endothelial cells.

OBJECTIVES

To investigate the protective effect of APC in a chlorhexidine gluconate (CG)-induced peritoneal fibrosis model.

METHODS

Peritoneal fibrosis was induced in wild-type as well as EPCR- and PAR1-deficient mice via daily injection of CG (0.2 mL of 0.1% CG in 15% ethanol and 85% saline) for 21 days with or without concomitant injection of recombinant human APC derivatives (50 μg/kg of bodyweight). The expression of proinflammatory cytokines and profibrotic markers as well as collagen deposition were analyzed using established methods.

RESULTS

CG significantly upregulated the expression of transforming growth factor-β1 in peritoneal tissues, which culminated in the deposition of excessive extracellular matrix proteins, thickening of the peritoneal membrane, and mesothelial-to-mesenchymal transition in damaged tissues. APC potently inhibited CG-induced peritoneal fibrosis and downregulated the expression of proinflammatory cytokines, collagen deposition, Smad3 phosphorylation, and markers of mesothelial-to-mesenchymal transition (α-smooth muscle actin, vimentin, and N-cadherin). APC also inhibited transforming growth factor-β1-mediated upregulation of α-smooth muscle actin, Smad3, and fibronectin in human primary mesothelial cells. Employing signaling-selective and anticoagulant-selective variants of APC and mutant mice deficient for either EPCR or PAR1, we demonstrated that the EPCR-dependent signaling function of APC through PAR1 activation was primarily responsible for its antifibrotic activity in the CG-induced peritoneal fibrosis model.

CONCLUSION

APC and signaling-selective variants of APC may have therapeutic potential for preventing or treating pathologies associated with peritoneal fibrosis.

Detecting traumatic brain injury-induced coagulopathy: What we are testing and what we are not

ABSTRACT

Coagulopathy after traumatic brain injury (TBI) is common and has been closely associated with poor clinical outcomes for the affected patients. Traumatic brain injury-induced coagulopathy (TBI-IC) is consumptive in nature and evolves rapidly from an injury-induced hypercoagulable state. Traumatic brain injury-induced coagulopathy defined by laboratory tests is significantly more frequent than clinical coagulopathy, which often manifests as secondary, recurrent, or delayed intracranial or intracerebral hemorrhage. This disparity between laboratory and clinical coagulopathies has hindered progress in understanding the pathogenesis of TBI-IC and developing more accurate and predictive tests for this severe TBI complication. In this review, we discuss laboratory tests used in clinical and research studies to define TBI-IC, with specific emphasis on what the tests detect and what they do not. We also offer perspective on developing more accurate and predictive tests for this severe TBI complication.

Protease-activated receptors in health and disease

Proteases are signaling molecules that specifically control cellular functions by cleaving protease-activated receptors (PARs). The four known PARs are members of the large family of G protein-coupled receptors. These transmembrane receptors control most physiological and pathological processes and are the target of a large proportion of therapeutic drugs. Signaling proteases include enzymes from the circulation; from immune, inflammatory epithelial, and cancer cells; as well as from commensal and pathogenic bacteria. Advances in our understanding of the structure and function of PARs provide insights into how diverse proteases activate these receptors to regulate physiological and pathological processes in most tissues and organ systems. The realization that proteases and PARs are key mediators of disease, coupled with advances in understanding the atomic level structure of PARs and their mechanisms of signaling in subcellular microdomains, has spurred the development of antagonists, some of which have advanced to the clinic. Herein we review the discovery, structure, and function of this receptor system, highlight the contribution of PARs to homeostatic control, and discuss the potential of PAR antagonists for the treatment of major diseases.

Diversification of PAR signaling through receptor crosstalk

Protease activated receptors (PARs) are among the first receptors shown to transactivate other receptors: noticeably, these interactions are not limited to members of the same family, but involve receptors as diverse as receptor kinases, prostanoid receptors, purinergic receptors and ionic channels among others. In this review, we will focus on the evidence for PAR interactions with members of their own family, as well as with other types of receptors. We will discuss recent evidence as well as what we consider as emerging areas to explore; from the signalling pathways triggered, to the physiological and pathological relevance of these interactions, since this additional level of molecular cross-talk between receptors and signaling pathways is only beginning to be explored and represents a novel mechanism providing diversity to receptor function and play important roles in physiology and disease.

3K3A-Activated Protein C Prevents Microglia Activation, Inhibits NLRP3 Inflammasome and Limits Ocular Inflammation

3K3A-Activated Protein C (APC) is a recombinant variant of the physiological anticoagulant APC with pleiotropic cytoprotective properties albeit without the bleeding risks. The anti-inflammatory activities of 3K3A-APC were demonstrated in multiple preclinical injury models, including various neurological disorders. We determined the ability of 3K3A-APC to inhibit ocular inflammation in a murine model of lipopolysaccharide (LPS)-induced uveitis. Leukocyte recruitment, microglia activation, NLRP3 inflammasome and IL-1β levels were assessed using flow cytometry, retinal cryosection histology, retinal flatmount immunohistochemistry and vascular imaging, with and without 3K3A-APC treatment. LPS triggered robust inflammatory cell recruitment in the posterior chamber. The 3K3A-APC treatment significantly decreased leukocyte numbers and inhibited leukocyte extravasation from blood vessels into the retinal parenchyma to a level similar to controls. Resident microglia, which underwent an inflammatory transition following LPS injection, remained quiescent in eyes treated with 3K3A-APC. An inflammation-associated increase in retinal thickness, observed in LPS-injected eyes, was diminished by 3K3A-APC treatment, suggesting its clinical relevancy. Finally, 3K3A-APC treatment inhibited inflammasome activation, determined by lower levels of NLRP3 and its downstream effector IL-1β. Our results highlight the anti-inflammatory properties of 3K3A-APC in ocular inflammation and suggest its potential use as a novel treatment for retinal diseases associated with inflammation.

GGCX mutants that impair hemostasis reveal the importance of processivity and full carboxylation to VKD protein function

γ-Glutamyl carboxylase (GGCX) generates multiple carboxylated Glus (Glas) in vitamin K-dependent (VKD) proteins that are required for their functions. GGCX is processive, remaining bound to VKD proteins throughout multiple Glu carboxylations, and this study reveals the essentiality of processivity to VKD protein function. GGCX mutants (V255M and S300F) whose combined heterozygosity in a patient causes defective clotting and calcification were studied using a novel assay that mimics in vivo carboxylation. Complexes between variant carboxylases and VKD proteins important to hemostasis (factor IX [FIX]) or calcification (matrix Gla protein [MGP]) were reacted in the presence of a challenge VKD protein that could potentially interfere with carboxylation of the VKD protein in the complex. The VKD protein in the complex with wild-type carboxylase was carboxylated before challenge protein carboxylation occurred and became fully carboxylated. In contrast, the V255M mutant carboxylated both forms at the same time and did not completely carboxylate FIX in the complex. S300F carboxylation was poor with both FIX and MGP. Additional studies analyzed FIX- and MGP-derived peptides containing the Gla domain linked to sequences that mediate carboxylase binding. The total amount of carboxylated peptide generated by the V255M mutant was higher than that of wild-type GGCX; however, the individual peptides were partially carboxylated. Analysis of the V255M mutant in FIX HEK293 cells lacking endogenous GGCX revealed poor FIX clotting activity. This study shows that disrupted processivity causes disease and explains the defect in the patient. Kinetic analyses also suggest that disrupted processivity may occur in wild-type carboxylase under some conditions (eg, warfarin therapy or vitamin K deficiency).

Markers for human haematopoietic stem cells: The disconnect between an identification marker and its function

The haematopoietic system is a classical stem cell hierarchy that maintains all the blood cells in the body. Haematopoietic stem cells (HSCs) are rare, highly potent cells that reside at the apex of this hierarchy and are historically some of the most well studied stem cells in humans and laboratory models, with haematopoiesis being the original system to define functional cell types by cell surface markers. Whilst it is possible to isolate HSCs to near purity, we know very little about the functional activity of markers to purify HSCs. This review will focus on the historical efforts to purify HSCs in humans based on cell surface markers, their putative functions and recent advances in finding functional markers on HSCs.

Endothelial cell protein C receptor regulates neutrophil extracellular trap-mediated rheumatoid arthritis disease progression

Endothelial cell protein C receptor (EPCR) is a 46 kDa transmembrane protein receptor, expressed in most immune cells (T cells, monocytes, dendritic cells, polymorphonuclear neutrophils [PMN]). EPCR reportedly plays a vital role in rheumatoid arthritis (RA). Our results confirmed that EPCR expression exists in the PMN of RA patients, and animal experiments demonstrated that down-regulation of EPCR expression affects disease progression in collagen-induced arthritis (CIA) mice. PMN is the immune cell type that first enters the site of inflammation in the early stages of inflammation. In the early stage of RA, PMN cells migrate into the joint cavity and function in the process of RA synovial inflammation, aggravating the bone destruction found in RA and mediating the progression of RA disease progression. We verified the differences in EPCR expression in PMN cells between RA and osteoarthritis (OA) patients by Western blot and then confirmed this difference in animals. We found that CIA mice treated with PMN-neutralizing antibody intervention had reduced disease performance. On this basis, EPCR was knocked down at the same time. The therapeutic effect of PMN-neutralizing antibody treatment was subsequently diminished. To explore the relationship between EPCR and PMN in RA, we used immunofluorescence to detect the expression of PMN-neutrophil extracellular traps (NETs) in RA patients and used EPCR neutralizing antibodies as an intervention. The results showed that the formation of PMN-NETs in RA patients increased. Finally, through in vitro intervention experiments involving EPCR and PMN transcriptome analysis of the peripheral blood of RA patients, we concluded that EPCR may regulate the formation of PMN-NETs in RA patients through the activated protein C (APC)-EPCR signaling pathway, thereby affecting the progression of disease in RA patients.

Identification of a broad lipid repertoire associated to the endothelial cell protein C receptor (EPCR)

Evidence is mounting that the nature of the lipid bound to the endothelial cell protein C receptor (EPCR) has an impact on its biological roles, as observed in anticoagulation and more recently, in autoimmune disease. Phosphatidylethanolamine and phosphatidylcholine species dominate the EPCR lipid cargo, yet, the extent of diversity in the EPCR-associated lipid repertoire is still unknown and remains to be uncovered. We undertook mass spectrometry analyses to decipher the EPCR lipidome, and identified species not yet described as EPCR ligands, such as phosphatidylinositols and phosphatidylserines. Remarkably, we found further, more structurally divergent lipids classes, represented by ceramides and sphingomyelins, both in less abundant quantities. In support of our mass spectrometry results and previous studies, high-resolution crystal structures of EPCR in three different space groups point to a prevalent diacyl phospholipid moiety in EPCR’s pocket but a mobile and ambiguous lipid polar head group. In sum, these studies indicate that EPCR can associate with varied lipid classes, which might impact its properties in anticoagulation and the onset of autoimmune disease.

Cleavage-Responsive Biofactory T Cells Suppress Infectious Diseases-Associated Hypercytokinemia

Severe infectious diseases, such as coronavirus disease 2019 (COVID-19), can induce hypercytokinemia and multiple organ failure. In spite of the growing demand for peptide therapeutics against infectious diseases, current small molecule-based strategies still require frequent administration due to limited half-life and enzymatic digestion in blood. To overcome this challenge, a strategy to continuously express multi-level therapeutic peptide drugs on the surface of immune cells, is established. Here, chimeric T cells stably expressing therapeutic peptides are presented for treatment of severe infectious diseases. Using lentiviral system, T cells are engineered to express multi-level therapeutic peptides with matrix metallopeptidases- (MMP-) and tumor necrosis factor alpha converting enzyme- (TACE-) responsive cleavage sites on the surface. The enzymatic cleavage releases γ-carboxyglutamic acid of protein C (PC-Gla) domain and thrombin receptor agonist peptide (TRAP), which activate endothelial protein C receptor (EPCR) and protease-activated receptor-1 (PAR-1), respectively. These chimeric T cells prevent vascular damage in tissue-engineered blood vessel and suppress hypercytokinemia and lung tissue damages in vivo, demonstrating promise for use of engineered T cells against sepsis and other infectious-related diseases.

Effects of oral anticoagulant therapy in patients with pulmonary diseases

Background

To evaluate the effect of oral anticoagulants (OACs) therapy, including vitamin K antagonist (VKA) and direct oral anticoagulants (DOAC) in patients with pulmonary diseases.

Methods

Literature from PubMed, MEDLINE, and Cochrane Library were screened until June 2022. Studies assessing OACs for pulmonary hypertension (PH), pulmonary embolism (PE), pulmonary fibrosis (PF), or chronic obstructive pulmonary disease (COPD) were evaluated for inclusion.

Results

Our study indicated that in patients with PH, PE, and COPD, OACs could significantly reduce the mortality risk, and the effects of VKA and DOACs without statistical difference in reducing the risk of recurrent embolism events. In patients with sclerosis-associated pulmonary arterial hypertension (SSc-PAH) or idiopathic pulmonary fibrosis (IPF), vitamin K antagonist (warfarin) significantly increased the mortality risk, while DOACs were not. As for the safety outcome of OACs, existing studies indicate that compared with patients treated with warfarin, the users of DOAC have a lower risk of major bleeding, while there is no statistical significance between them in non-major bleeding events. In current guidelines, the anticoagulation regimen for patients with pulmonary disease has not been defined. The results of our study confirm that DOACs (apixaban, rivaroxaban, dabigatran, and edoxaban) are superior to VKAs in the efficacy and safety outcomes of patients with pulmonary disease.

Conclusions

Oral anticoagulant therapy brings benefits to patients with PH, PE, or COPD, while the anticoagulation regimen for patients with SSc-PAH or IPF requires serious consideration. Compared with VKA, DOAC is a non-inferior option for anticoagulation in pulmonary disease treatment. Further studies are still needed to provide more reliable evidence about the safety outcome of pulmonary disease anticoagulation.

Pathophysiology of Cerebral Malaria: Implications of MSCs as A Regenerative Medicinal Tool

The severe form of malaria, i.e., cerebral malaria caused by Plasmodium falciparum, is a complex neurological syndrome. Surviving persons have a risk of behavioral difficulties, cognitive disorders, and epilepsy. Cerebral malaria is associated with multiple organ dysfunctions. The adhesion and accumulation of infected RBCs, platelets, and leucocytes (macrophages, CD4⁺ and CD8⁺ T cells, and monocytes) in the brain microvessels play an essential role in disease progression. Micro-vascular hindrance by coagulation and endothelial dysfunction contributes to neurological damage and the severity of the disease. Recent studies in human cerebral malaria and the murine model of cerebral malaria indicate that different pathogens as well as host-derived factors are involved in brain microvessel adhesion and coagulation that induces changes in vascular permeability and impairment of the blood-brain barrier. Efforts to alleviate blood-brain barrier dysfunction and de-sequestering of RBCs could serve as adjunct therapies. In this review, we briefly summarize the current understanding of the pathogenesis of cerebral malaria, the role of some factors (NK cells, platelet, ANG-2/ANG-1 ratio, and PfEMP1) in disease progression and various functions of Mesenchymal stem cells. This review also highlighted the implications of MSCs as a regenerative medicine.

N-Glycosylation Deficiency Reduces the Activation of Protein C and Disrupts the Endothelial Barrier Integrity

Phosphomannomutase 2 (PMM2) deficiency is the most prevalent congenital disorder of glycosylation. It is associated with coagulopathy, including protein C deficiency. Since all components of the anticoagulant and cytoprotective protein C system are glycosylated, we sought to investigate the impact of an N-glycosylation deficiency on this system as a whole. To this end, we developed a PMM2 knockdown model in the brain endothelial cell line hCMEC/D3. The resulting PMM2^low cells were less able to generate activated protein C (APC), due to lower surface expression of thrombomodulin and endothelial protein C receptor. The low protein levels were due to downregulated transcription of the corresponding genes (THBD and PROCR, respectively), which itself was related to downregulation of transcription regulators Krüppel-like factors 2 and 4 and forkhead box C2. PMM2 knockdown was also associated with impaired integrity of the endothelial cell monolayer-partly due to an alteration in the structure of VE-cadherin in adherens junctions. The expression of protease-activated receptor 1 (involved in the cytoprotective effects of APC on the endothelium) was not affected by PMM2 knockdown. Thrombin stimulation induced hyperpermeability in PMM2^low cells. However, pretreatment of cells with APC before thrombin simulation was still associated with a barrier-protecting effect. Taken as a whole, our results show that the partial loss of PMM2 in hCMEC/D3 cells is associated with impaired activation of protein C and a relative increase in barrier permeability.

EPCR-PAR1 biased signaling regulates perfusion recovery and neovascularization in peripheral ischemia

Blood clot formation initiates ischemic events, but coagulation roles during postischemic tissue repair are poorly understood. The endothelial protein C receptor (EPCR) regulates coagulation, as well as immune and vascular signaling, by protease activated receptors (PARs). Here, we show that endothelial EPCR-PAR1 signaling supports reperfusion and neovascularization in hindlimb ischemia in mice. Whereas deletion of PAR2 or PAR4 did not impair angiogenesis, EPCR and PAR1 deficiency or PAR1 resistance to cleavage by activated protein C caused markedly reduced postischemic reperfusion in vivo and angiogenesis in vitro. These findings were corroborated by biased PAR1 agonism in isolated primary endothelial cells. Loss of EPCR-PAR1 signaling upregulated hemoglobin expression and reduced endothelial nitric oxide (NO) bioavailability. Defective angiogenic sprouting was rescued by the NO donor DETA-NO, whereas NO scavenging increased hemoglobin and mesenchymal marker expression in human and mouse endothelial cells. Vascular specimens from patients with ischemic peripheral artery disease exhibited increased hemoglobin expression, and soluble EPCR and NO levels were reduced in plasma. Our data implicate endothelial EPCR-PAR1 signaling in the hypoxic response of endothelial cells and identify suppression of hemoglobin expression as an unexpected link between coagulation signaling, preservation of endothelial cell NO bioavailability, support of neovascularization, and prevention of fibrosis.

Inherited thrombophilia transpires with severe coronary arterial thrombosis in wide range of age backgrounds: A report of 3 cases

Introduction

and importance: Protein C and S deficiency are some of the coagulation cascade disorders which may also contributes not only to venous thromboembolism (VTE), but also rarely to arterial thrombosis. Here we present a report of 3 severe coronary artery disease (CAD) cases ranging from very young to elderly patients with concomitant inherited thrombophilia.

Case presentation

The first case was a chronic coronary syndrome from a very young male patient with history of VTE without any other risk factor of CAD. The second case was about premature CAD with triple chronic total occlusion (RCA, LCX, LAD) in patient under 45 years old, with single risk factor. The third case was about accelerated atherosclerosis progression from previously non significant stenosis in RCA into total occlusion in RCA and inferior STEMI in old patient on supposely adequate double anti platelet agent.

Clinical discussion

All patients had protein C and/or S deficiency and first degree family history of VTE, therefore inherited thrombophilia was diagnosed. We gave them oral anticoagulant in addition to their standard treatment for secondary prevention with good outcome and without further adverse event.

Conclusion

It is important to raise awareness to perform screening inherited thrombophilia as an important risk factor for CAD in special subgroup such as young age patient with rapid course progression and family history of VTE. The use of oral anticoagulants as either prophylactic or therapeutic purpose in patients with inherited thrombophilia are safe and effective. However, further research is still needed.

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Inherited thrombophilia is a rare disease that can causes coronary arterial thrombosis.

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Inherited thrombophilia screening should be done in special subgroup of patients.

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There is no treatment guideline for CAD patients with inherited thrombophilia.