Rapid clearing CT-001 restored hemostasis in mice with coagulopathy induced by activated protein C.

BACKGROUND: Activated protein C (APC) is one of the mechanisms contributing to coagulopathy, which is associated with high mortality. The counteraction of the APC pathway could help ameliorate bleeding. However, patients also transform frequently from a hemorrhagic state to a prothrombotic state at a later time. Therefore, a prohemostatic therapeutic intervention should take this thrombotic risk into consideration. OBJECTIVES: CT-001 is a novel factor VIIa (FVIIa) with enhanced activity and desialylated N-glycans for rapid clearance. We assessed CT-001 clearance in multiple species and its ability to reverse APC-mediated coagulopathic blood loss. METHODS: The N-glycans on CT-001 were characterized by liquid chromatography-mass spectrometry. Three species were used to evaluate the pharmacokinetics of the molecule. The potency and efficacy of CT-001 under APC pathway-induced coagulopathic conditions were assessed by coagulation assays and bleeding models. RESULTS: The N-glycosylation sites of CT-001 had high occupancy of desialylated N-glycans. CT-001 exhibited 5 to 16 times higher plasma clearance in human tissue factor knockin mice, rats, and cynomolgus monkeys than wildtype FVIIa. CT-001 corrected the activated partial thromboplastin time and thrombin generation of coagulopathic plasma to normal in in vitro studies. In an APC-mediated saphenous vein bleeding model, 3 mg/kg of CT-001 reduced bleeding time in comparison with wildtype FVIIa. The correction of bleeding by CT-001 was also observed in a coagulopathic tail amputation severe hemorrhage mouse model. The efficacy of CT-001 is independent of the presence of tranexamic acid, and the combination of CT-001 and tranexamic acid does not lead to increased thrombogenicity. CONCLUSION: CT-001 corrected APC pathway-mediated coagulopathic conditions in preclinical studies and could be a potentially safe and effective procoagulant agent for addressing APC-mediated bleeding.

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.

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.

Identifying molecular phenotypes in sepsis: an analysis of two prospective observational cohorts and secondary analysis of two randomised controlled trials.

BACKGROUND: In sepsis and acute respiratory distress syndrome (ARDS), heterogeneity has contributed to difficulty identifying effective pharmacotherapies. In ARDS, two molecular phenotypes (hypoinflammatory and hyperinflammatory) have consistently been identified, with divergent outcomes and treatment responses. In this study, we sought to derive molecular phenotypes in critically ill adults with sepsis, determine their overlap with previous ARDS phenotypes, and evaluate whether they respond differently to treatment in completed sepsis trials. METHODS: We used clinical data and plasma biomarkers from two prospective sepsis cohorts, the Validating Acute Lung Injury biomarkers for Diagnosis (VALID) study (N=1140) and the Early Assessment of Renal and Lung Injury (EARLI) study (N=818), in latent class analysis (LCA) to identify the optimal number of classes in each cohort independently. We used validated models trained to classify ARDS phenotypes to evaluate concordance of sepsis and ARDS phenotypes. We applied these models retrospectively to the previously published Prospective Recombinant Human Activated Protein C Worldwide Evaluation in Severe Sepsis and Septic Shock (PROWESS-SHOCK) trial and Vasopressin and Septic Shock Trial (VASST) to assign phenotypes and evaluate heterogeneity of treatment effect. FINDINGS: A two-class model best fit both VALID and EARLI (p<0·0001). In VALID, 804 (70·5%) of the 1140 patients were classified as hypoinflammatory and 336 (29·5%) as hyperinflammatory; in EARLI, 530 (64·8%) of 818 were hypoinflammatory and 288 (35·2%) hyperinflammatory. We observed higher plasma pro-inflammatory cytokines, more vasopressor use, more bacteraemia, lower protein C, and higher mortality in the hyperinflammatory than in the hypoinflammatory phenotype (p<0·0001 for all). Classifier models indicated strong concordance between sepsis phenotypes and previously identified ARDS phenotypes (area under the curve 0·87-0·96, depending on the model). Findings were similar excluding participants with both sepsis and ARDS. In PROWESS-SHOCK, 1142 (68·0%) of 1680 patients had the hypoinflammatory phenotype and 538 (32·0%) had the hyperinflammatory phenotype, and response to activated protein C differed by phenotype (p=0·0043). In VASST, phenotype proportions were similar to other cohorts; however, no treatment interaction with the type of vasopressor was observed (p=0·72). INTERPRETATION: Molecular phenotypes previously identified in ARDS are also identifiable in multiple sepsis cohorts and respond differently to activated protein C. Molecular phenotypes could represent a treatable trait in critical illness beyond the patient's syndromic diagnosis. FUNDING: US National Institutes of Health.

3K3A-Activated Protein C Inhibits Choroidal Neovascularization Growth and Leakage and Reduces NLRP3 Inflammasome, IL-1ß, and Inflammatory Cell Accumulation in the Retina.

3K3A-Activated Protein C (APC) is a recombinant variant of the physiological anticoagulant APC with cytoprotective properties and reduced bleeding risks. We studied the potential use of 3K3A-APC as a multi-target therapeutic option for choroidal neovascularization (CNV), a common cause of vision loss in age-related macular degeneration. CNV was induced by laser photocoagulation in a murine model, and 3K3A-APC was intravitreally injected. The impact of 3K3A-APC treatment on myeloid and microglia cell activation and recruitment and on NLRP3 inflammasome, IL-1ß, and VEGF levels was assessed using cryosection, retinal flat-mount immunohistochemistry and vascular imaging. Additionally, we evaluated the use of fluorescein angiography as a surrogate marker for in vivo evaluation of the efficacy of 3K3A-APC treatment against leaking CNV lesions. Our results demonstrated that 3K3A-APC treatment significantly reduced the accumulation and activation of myeloid cells and microglia in the CNV area and decreased the NLRP3 and IL-1ß levels at the CNV site and the surrounding retina. Furthermore, 3K3A-APC treatment resulted in leakage regression and CNV growth suppression. These findings indicate that the anti-inflammatory activities of 3K3A-APC contribute to CNV inhibition. Our study suggests the potential use of 3K3A-APC as a novel multi-target treatment for CNV.

Safety and efficacy of an anti-human APC antibody for prophylaxis of congenital factor deficiencies in preclinical models.

Rebalance of coagulation and anticoagulation to achieve a hemostatic effect has recently gained attention as an alternative therapeutic strategy for hemophilia. We engineered a humanized chimeric antibody, SR604, based on a previously published murine antibody, HAPC1573, which selectively blocks the anticoagulant activity of human activated protein C (APC). SR604 effectively blocked the anticoagulation activities of APC in human plasma deficient in various coagulation factors in vitro with affinities ∼60 times greater than that of HAPC1573. SR604 exhibited prophylactic and therapeutic efficacy in the tail-bleeding and knee-injury models of hemophilia A and B mice expressing human APC (humanized hemophilic mice). SR604 did not interfere with the cytoprotection and endothelial barrier function of APC, nor were there obvious toxicity effects in humanized hemophilic mice. Pharmacokinetic study showed a high bioavailability (106%) of subcutaneously injected SR604 in cynomolgus monkeys. These results demonstrate that SR604 is expected to be a safe and effective therapeutic and/or prophylactic agent with a prolonged half-life for patients with congenital factor deficiencies including hemophilia A and B.

Severe Neonatal Interstitial Lung Disease Caused by a Rare Surfactant Protein C Mutation.

Childhood interstitial lung disease (chILD) is a collective term for a group of rare lung disorders of heterogeneous origin. Surfactant dysfunction disorders are a cause of chILD with onset during the neonatal period and infancy. Clinical signs of tachypnea and hypoxemia are nonspecific and usually caused by common conditions like lower respiratory tract infections. We report on a full-term male newborn who was readmitted to the hospital at 7 days of age with marked tachypnea and poor feeding during the respiratory syncytial virus season. After exclusion of infection and other, more common congenital disorders, chILD was diagnosed using chest computed tomography and genetic analysis. A likely pathogenic heterozygous variant of SFTPC (c.163C>T, L55F) was detected by whole exome sequencing. The patient received supplemental oxygen and noninvasive respiratory support and was treated with intravenous methylprednisolone pulses and hydroxychloroquine. Despite the treatment, his respiratory situation deteriorated continuously, leading to several hospitalizations and continuous escalation of noninvasive ventilatory support. At 6 months of age, the patient was listed for lung transplant and transplanted successfully aged 7 months.

Kidney Transplantation for a Patient With Protein C Deficiency Using Activated Protein C Concentrate: A Case Report.

BACKGROUND: Thrombophilia causes thrombosis after kidney transplantation (KT). Protein C deficiency is a rare form of hereditary thrombophilia. To our knowledge, there are few reports on KT for patients with protein C deficiency, and there are no reports of KT in patients with protein C deficiency administered with activated protein C concentrate. METHOD: Here we reported the case of a patient with protein C deficiency who underwent KT without the occurrence of any fresh thrombosis after administration of an activated protein C concentrate. The patients was a 49-year-old woman diagnosed with immunoglobulin A nephropathy at 20 years of age. During pregnancy, she experienced deep vein thrombosis of the lower extremities and pulmonary embolism for which she was started on warfarin. After a thorough examination, the patient was diagnosed with protein C deficiency. The patient had end-stage kidney disease and received a preemptive living donor kidney transplant from her mother. RESULTS: To prevent thrombosis, we switched from oral warfarin to continuous heparin 7 days before surgery. Heparin was discontinued 6 hours before surgery, and continuous activated protein C concentrate was administered 12 hours before surgery. Heparin administration was resumed 6 hours after the surgery. Warfarin administration was restarted 3 days after the surgery, and heparin was discontinued 11 days post-surgery. The surgery was performed without complications. After the KT, the patient's renal function steadily improved, and no fresh thrombosis were observed. CONCLUSIONS: Thrombosis can cause graft loss and pulmonary embolism, thus appropriate administration of activated protein C concentrate may help prevent thrombosis.

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-1ß 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-1ß. 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.

In Silico Identification of Potential Insect Peptides against Biofilm-Producing Staphylococcus aureus.

Biofilm-producing Staphylococcus aureus (SA) strains are frequently found in medical environments, from surgical/ wound sites, medical devices. These biofilms reduce the efficacy of applied antibiotics during the treatment of several infections, such as cystic fibrosis, endocarditis, or urinary tract infections. Thus, the development of potential therapeutic agents to destroy the extra protective biofilm layers or to inhibit the biofilm-producing enzymes is urgently needed. Advanced and cost-effective bioinformatics tools are advantageous in locating and speeding up the selection of antibiofilm candidates. Based on the potential drug characteristics, we have selected one-hundred thirty-three antibacterial peptides derived from insects to assess for their antibiofilm potency via molecular docking against five putative biofilm formation and regulated target enzymes: the staphylococcal accessory regulator A or SarA (PDB ID: 2FRH), 4,4'-diapophytoene synthase or CrtM (PDB ID: 2ZCQ), clumping factor A or ClfA (PDB ID: 1N67) and serine-aspartate repeat protein C or SdrC (PDB ID: 6LXH) and sortase A or SrtA (PDB ID: 1T2W) of SA bacterium. In this study, molecular docking was performed using HPEPDOCK and HDOCK servers, and molecular interactions were examined using BIOVIA Discovery Studio Visualizer-2019. The docking score (kcal/mol) range of five promising antibiofilm peptides against five targets was recorded as follows: diptericin A (-215.52 to -303.31), defensin (-201.11 to -301.92), imcroporin (-212.08 to -287.64), mucroporin (-228.72 to -286.76), apidaecin II (-203.90 to -280.20). Among these five, imcroporin and mucroporin were 13 % each, while defensin contained only 1 % of positive net charged residues (Arg+Lys) projected through ProtParam and NetWheels tools. Similarly, imcroporin, mucroporin and apidaecin II were 50 %, while defensin carried 21.05 % of hydrophobic residues predicted by the tool PEPTIDE. 2.0. Most of the peptides exhibited potential characteristics to inhibit S. aureus-biofilm formation via disrupting the cell membrane and cytoplasmic integrity. In summary, the proposed hypothesis can be considered a cost-effective platform for selecting the most promising bioactive drug candidates within a limited timeframe with a greater chance of success in experimental and clinical studies.

NNMT contributes to high metastasis of triple negative breast cancer by enhancing PP2A/MEK/ERK/c-Jun/ABCA1 pathway mediated membrane fluidity.

Elucidating the mechanism for high metastasis capacity of triple negative breast cancers (TNBC) is crucial to improve treatment outcomes of TNBC. We have recently reported that nicotinamide N-methyltransferase (NNMT) is overexpressed in breast cancer, especially in TNBC, and predicts poor survival of patients undergoing chemotherapy. Here, we aimed to determine the function and mechanism of NNMT on metastasis of TNBC. Additionally, analysis of public datasets indicated that NNMT is involved in cholesterol metabolism. In vitro, NNMT overexpression promoted migration and invasion of TNBCs by reducing cholesterol levels in the cytoplasm and cell membrane. Mechanistically, NNMT activated MEK/ERK/c-Jun/ABCA1 pathway by repressing protein phosphatase 2A (PP2A) activity leading to cholesterol efflux and membrane fluidity enhancement, thereby promoting the epithelial-mesenchymal transition (EMT) of TNBCs. In vivo, the metastasis capacity of TNBCs was weakened by targeting NNMT. Collectively, our findings suggest a new molecular mechanism involving NNMT in metastasis and poor survival of TNBC mediated by PP2A and affecting cholesterol metabolism.

The Vascular Endothelium and Coagulation: Homeostasis, Disease, and Treatment, with a Focus on the Von Willebrand Factor and Factors VIII and V.

The vascular endothelium has several important functions, including hemostasis. The homeostasis of hemostasis is based on a fine balance between procoagulant and anticoagulant proteins and between fibrinolytic and antifibrinolytic ones. Coagulopathies are characterized by a mutation-induced alteration of the function of certain coagulation factors or by a disturbed balance between the mechanisms responsible for regulating coagulation. Homeostatic therapies consist in replacement and nonreplacement treatments or in the administration of antifibrinolytic agents. Rebalancing products reestablish hemostasis by inhibiting natural anticoagulant pathways. These agents include monoclonal antibodies, such as concizumab and marstacimab, which target the tissue factor pathway inhibitor; interfering RNA therapies, such as fitusiran, which targets antithrombin III; and protease inhibitors, such as serpinPC, which targets active protein C. In cases of thrombophilia (deficiency of protein C, protein S, or factor V Leiden), treatment may consist in direct oral anticoagulants, replacement therapy (plasma or recombinant ADAMTS13) in cases of a congenital deficiency of ADAMTS13, or immunomodulators (prednisone) if the thrombophilia is autoimmune. Monoclonal-antibody-based anti-vWF immunotherapy (caplacizumab) is used in the context of severe thrombophilia, regardless of the cause of the disorder. In cases of disseminated intravascular coagulation, the treatment of choice consists in administration of antifibrinolytics, all-trans-retinoic acid, and recombinant soluble human thrombomodulin.

Factor VII, EPCR, aPC Modulators: novel treatment for neuroinflammation.

BACKGROUND: Inflammation and coagulation are linked and pathogenic in neuroinflammatory diseases. Protease-activated receptor 1 (PAR1) can be activated both by thrombin, inducing increased inflammation, and activated protein C (aPC), inducing decreased inflammation. Modulation of the aPC-PAR1 pathway may prevent the neuroinflammation associated with PAR1 over-activation. METHODS: We synthesized a group of novel molecules based on the binding site of FVII/aPC to the endothelial protein C receptor (EPCR). These molecules modulate the FVII/aPC-EPCR pathway and are therefore named FEAMs-Factor VII, EPCR, aPC Modulators. We studied the molecular and behavioral effects of a selected FEAM in neuroinflammation models in-vitro and in-vivo. RESULTS: In a lipopolysaccharide (LPS) induced in-vitro model, neuroinflammation leads to increased thrombin activity compared to control (2.7 ± 0.11 and 2.23 ± 0.13 mU/ml, respectively, p = 0.01) and decreased aPC activity (0.57 ± 0.01 and 1.00 ± 0.02, respectively, p < 0.0001). In addition, increased phosphorylated extracellular regulated kinase (pERK) (0.99 ± 0.13, 1.39 ± 0.14, control and LPS, p < 0.04) and protein kinase B (pAKT) (1.00 ± 0.09, 2.83 ± 0.81, control and LPS, p < 0.0002) levels indicate PAR1 overactivation, which leads to increased tumor necrosis factor-alpha (TNF-α) level (1.00 ± 0.04, 1.35 ± 0.12, control and LPS, p = 0.02). In a minimal traumatic brain injury (mTBI) induced neuroinflammation in-vivo model in mice, increased thrombin activity, PAR1 activation, and TNF-α levels were measured. Additionally, significant memory impairment, as indicated by a lower recognition index in the Novel Object Recognition (NOR) test and Y-maze test (NOR: 0.19 ± 0.06, -0.07 ± 0.09, p = 0.03. Y-Maze: 0.50 ± 0.03, 0.23 ± 0.09, p = 0.02 control and mTBI, respectively), as well as hypersensitivity by hot-plate latency (16.6 ± 0.89, 12.8 ± 0.56 s, control and mTBI, p = 0.01), were seen. FEAM prevented most of the molecular and behavioral negative effects of neuroinflammation in-vitro and in-vivo, most likely through EPCR-PAR1 interactions. CONCLUSION: FEAM is a promising tool to study neuroinflammation and a potential treatment for a variety of neuroinflammatory diseases.

A Series of 14 Polish Patients with Thrombotic Events and PC Deficiency-Novel c.401-1G>A PROC Gene Splice Site Mutation in a Patient with Aneurysms

Objectives: Protein C (PC) deficiency is an inherited thrombophilia with a prevalence of 0.5% in the general population and 3% in subjects with a first-time deep vein thrombosis (DVT). Here we report a series of 14 PC-deficient Polish patients with comprehensive clinical and molecular characteristics, including long-term follow-up data and a deep mutational analysis of the PROC gene. Patients and Methods: Fourteen unrelated probands (mean ± SD age 43.8 ± 13.0 years) with suspicion of PC deficiency, who experienced thromboembolic events and a majority of whom received anticoagulants (92.8%), were screened for PROC mutations by sequencing the nine PROC exons and their flanking intron regions. Results: Ten probands (71.4%) had missense mutations, two patients (14.3%) carried nonsense variants, and the other two subjects (14.3%) had splice-site mutations, the latter including the c.401-1G>A variant, reported here for the very first time. The proband carrying the c.401-1A allele had a hepatic artery aneurysm with a highly positive family history of aneurysms and the absence of any mutations known to predispose to this vascular anomaly. Conclusion: A novel detrimental PROC mutation was identified in a family with aneurysms, which might suggest yet unclear links of thrombophilia to vascular anomalies, including aneurysms at atypical locations in women. The present case series also supports data indicating that novel oral anticoagulants (NOACs) are effective in PC deficient patients.

Blocking human protein C anticoagulant activity improves clotting defects of hemophilia mice expressing human protein C.

Hemophilia A and B are hereditary coagulation defects resulting in unstable blood clotting and recurrent bleeding. Current factor replacement therapies have major limitations such as the short half-life of the factors and development of inhibitors. Alternative approaches to rebalance the hemostasis by inhibiting the anticoagulant pathways have recently gained considerable interest. In this study, we tested the therapeutic potential of a monoclonal antibody, HAPC1573, that selectively blocks the anticoagulant activity of human activated protein C (APC). We generated F8-/- or F9-/- hemophilia mice expressing human protein C by genetically replacing the murine Proc gene with the human PROC. The resulting PROC+/+;F8-/- or PROC+/+;F9-/- mice had bleeding characteristics similar to their corresponding F8-/- or F9-/- mice. Pretreating the PROC+/+;F8-/- mice with HAPC1573 shortened the tail bleeding time. HAPC1573 pretreatment significantly reduced mortality and alleviated joint swelling, similar to those treated with either FVIII or FIX, of either PROC+/+;F8-/- or PROC+/+;F9-/- mice in a needle puncture-induced knee-joint bleeding model. Additionally, we found that HAPC1573 significantly improved the thrombin generation of PROC+/+;F8-/- mice but not F8-/- mice, indicating that HAPC1573 enhanced the coagulant activity of hemophilia mice by modulating human APC in vivo. We further documented that HAPC1573 inhibited the APC anticoagulant activity to improve the clotting time of human plasma deficient of FVIII, FIX, FXI, FVII, VWF, FV, or FX. These results demonstrate that selectively blocking the anticoagulant activity of human APC may be an effective therapeutic and/or prophylactic approach for bleeding disorders lacking FVIII, FIX, or other clotting factors.

Activated Protein C Strengthens Cardiac Tolerance to Ischemic Insults in Aging.

BACKGROUND: APC (activated protein C) is a plasma serine protease with anticoagulant and anti-inflammatory activities. EPCR (Endothelial protein C receptor) is associated with APC's activity and mediates its downstream signaling events. APC exerts cardioprotective effects during ischemia and reperfusion (I/R). This study aims to characterize the role of the APC-EPCR axis in ischemic insults in aging. METHODS: Young (3-4 months) and aged (24-26 months) wild-type C57BL/6J mice, as well as EPCR point mutation (EPCRR84A/R84A) knockin C57BL/6J mice incapable of interaction with APC and its wild type of littermate C57BL/6J mice, were subjected to I/R. Wild-type APC, signaling-selective APC-2Cys, or anticoagulant-selective APC-E170A were administrated before reperfusion. RESULTS: The results demonstrated that cardiac I/R reduces APC activity, and the APC activity was impaired in the aged versus young hearts possibly attributable to the declined EPCR level with aging. Serum EPCR measurement showed that I/R triggered the shedding of membrane EPCR into circulation, while administration of APC attenuated the I/R-induced EPCR shedding in both young and aged hearts. Subsequent echocardiography showed that APC and APC-2Cys but not APC-E170A ameliorated cardiac dysfunction during I/R in both young and aged mice. Importantly, APC elevated the resistance of the aged heart to ischemic insults through stabilizing EPCR. However, all these cardioprotective effects of APC were blunted in the EPCRR84A/R84A mice versus its wild-type littermates. The ex vivo working heart and metabolomics results demonstrated that AMPK (AMP-activated protein kinase) mediates acute adaptive response while AKT (protein kinase B) is involved in chronic metabolic programming in the hearts with APC treatment. CONCLUSIONS: I/R stress causes shedding of the membrane EPCR in the heart, and administration of APC prevents I/R-induced cardiac EPCR shedding that is critical for limiting cardiac damage in aging.

Circulating Histones in Sepsis: Potential Outcome Predictors and Therapeutic Targets.

Sepsis is defined as a life-threatening organ dysfunction caused by a dysregulated host response to infection and is associated with high morbidity and mortality. Circulating histones (CHs), a group of damage-associated molecular pattern molecules mainly derived from neutrophil extracellular traps, play a crucial role in sepsis by mediating inflammation response, organ injury and death through Toll-like receptors or inflammasome pathways. Herein, we first elucidate the molecular mechanisms of histone-induced inflammation amplification, endothelium injury and cascade coagulation activation, and discuss the close correlation between elevated level of CHs and disease severity as well as mortality in patients with sepsis. Furthermore, current state-of-the-art on anti-histone therapy with antibodies, histone-binding proteins (namely recombinant thrombomodulin and activated protein C), and heparin is summarized to propose promising approaches for sepsis treatment.

Long-term outcomes of intravitreal activated protein C injection for ischemic central retinal vein occlusion: an extension trial.

PURPOSE: Our previous 1-year pilot study evaluated the efficacy of intravitreally injected activated protein C (APC) in 10 eyes with ischemic central retinal vein occlusion (CRVO). The reperfusion of the areas of retinal nonperfusion (RNP) exceeded 50% of the baseline in five (50%) eyes 1 year after the APC injection. The current study evaluated the long-term efficacy and safety of intravitreal APC. METHODS: The 10 eyes in the pilot study were included in this study. Other treatments were administered at the physicians' discretion after the pilot study. We evaluated visual acuity (VA), central retinal thickness (CRT) and perfusion status, and adverse events and severity over the long term. RESULTS: The median follow-up was 60 months (range, 48-68 months). Compared with baseline, the post-treatment VA improved significantly (P < 0.001) from 1.39 to 1.06 logarithm of the minimum angle of resolution. The CRT improved significantly (P < 0.001) from 1090 to 195 µm at the last visit. The RNP areas decreased from an average 29.7 disc areas (DAs) at baseline to an average 16.5 DAs at the last examination (mean, 40 ± 6.5 months after the first APC treatment). No adverse events were related to intravitreal APC. CONCLUSION: No complications were associated with intravitreal APC, the clinical course improved, and improved RNP was maintained for the long term, suggesting that intravitreal APC may be an alternative treatment for CRVO.

Old drug, new Trick? The rationale for the treatment of COVID-19 with activated protein C.

As the COVID-19 pandemic continues, researchers seek to identify efficacious treatments. Current approaches to COVID-19 therapeutics focus on antiviral agents, convalescent plasma, monoclonal antibodies, immunomodulators and more traditional therapies such as steroids [1-6]. Reversing disturbances in coagulation has also been identified as a priority area for candidate therapies, such as through the Accelerating COVID-19 Therapeutic Interventions and Vaccines 4 adaptive clinical trial (ACTIV-4) which is currently evaluating aspirin, heparins and apixaban [7]. Since there is a clear relationship between mechanisms of coagulation and the immune response, it is possible that reversing disturbances in coagulation may diminish the dysregulated immune response observed in COVID-19. The basis for this hypothesis is described below and is followed by discussion of a proposed candidate therapy - activated protein C. By treating COVID-19 patients using a novel approach, which does not focus on immune-based or antiviral treatments, but instead which addresses both the anti-thrombotic and inflammatory consequences of infection, the hope is that new therapeutic targets can be considered and new candidate therapies, such as activated protein C, may be evaluated.