Cross-linked Fibrin Research Articles

D-dimer as a Predictor of ICU Admission and Mortality in COVID-19 Patients: Insights From a Two-Year Retrospective Study From a Tertiary Care Center in South India.

Introduction Severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2)-induced pneumonitis results in a prothrombotic and hypercoagulable state. Prognostic indicators are crucial for identifying patients at risk of complications. D-dimer, a degradation product of cross-linked fibrin, is a specific marker for thrombosis. Elevated D-dimer levels have been strongly correlated with poor prognosis and increased severity of illness in COVID-19 patients. Given D-dimer's eight-hour half-life, periodic measurement is necessary to track disease progression. This study aimed to analyze and derive threshold and peak D-dimer values to predict outcomes in COVID-19 patients, comparing those treated in isolation wards to those requiring intensive care. Methods This two-year retrospective observational study included patients above 18 years with confirmed COVID-19. Patients were categorized into those treated in isolation wards and those admitted to the intensive care unit (ICU). Based on the outcome, they were further divided into survivors and non-survivors. Demographic and outcome-related data were collected from the hospital's laboratory information system. Serial D-dimer measurements were taken at eight time points. Statistical analysis was performed using the Mann-Whitney test for laboratory values and the chi-square test for demographic data. Receiver operating characteristic (ROC) curve analysis was utilized to derive critical D-dimer values. The area under the curve (AUC) was calculated for initial and peak D-dimer values. Results Of 2.149 patients with confirmed COVID-19, 811 (38%) presented with elevated D-dimer levels. ICU admission was required for 239 patients, either due to direct admission or worsening conditions. An initial D-dimer value of ≥0.93 mg/L FEU indicated the need for ICU admission, while a peak D-dimer value of 5.65 mg/L FEU predicted mortality. The AUC for the initial D-dimer was 0.60 (95% CI: 0.55-0.64), indicating moderate discriminatory power. The AUC for the peak D-dimer was 0.58 (95% CI: 0.54-0.62), suggesting lower predictive accuracy for peak values. Sensitivity was high for both initial (0.925) and peak (0.960) D-dimer values, although specificity was lower, especially for the peak D-dimer (0.486), resulting in a higher rate of false positives. Among the ICU patients, the age range was 27-97 years, with a mean of 53.5 years. Males were more affected than females (71% vs. 29%), with a male-to-female ratio of 1.4:1. Of the ICU patients, 64.8% recovered, while 35.2% succumbed to the disease. Younger patients (mean age: 50.5 ± 12 years) recovered faster than older patients (mean age: 64 ± 16 years), with a significant difference in recovery time (p < 0.001). Gender did not significantly impact outcomes (p = 0.743). Survivors spent less time in the ICU (3-7 days) compared to non-survivors (4-14 days) (p = 0.041). Conclusion Serial D-dimer monitoring is essential for predicting outcomes and guiding treatment in COVID-19 patients. Initial and peak D-dimer values can help identify patients requiring intensive care and those at risk of mortality, allowing for timely interventions. D-dimer levels should be integrated into routine clinical assessments for managing COVID-19 patients.

Aggregation-Disruption-Induced Multi-Scale Mediating Strategy for Anticoagulation in Blood-Contacting Devices.

Minimally invasive blood-contacting interventional devices are increasingly used to treat cardiovascular diseases. However, the risk of device-related thrombosis remains a significant concern, particularly the formation of cycling thrombi, which pose life-threatening risks. To better understand the interactions between these devices and blood, the initial stages of coagulation contact activation on extrinsic surfaces areinvestigated. Direct force measurements reveals that activated contact factors stimulate the intrinsic coagulation pathway and promote surface crosslinking of fibrin. Furthermore, fibrin aggregation is disrupted by surface-grafted inhibitors, as confirmed by ex vivo coagulation tests. An engineered serum protein with zwitterion grafts to resist the deposition of biological species such as fibrin, platelets, and red blood cells is also developed. Simultaneously, a protease inhibitor-based coacervate is incorporated into the coating to inhibit the intrinsic pathway effectively. The loaded coacervate can be released and reloaded through modulation of catechol-amine interactions, facilitating material regeneration. The strategy offers a novel multi-scale mediation strategy that simultaneously inhibits nanoscale coagulation factors and resists microscale thrombus aggregation, providing a long-term solution for anticoagulation in blood-contacting devices.

Development and Epitope Mapping of Seven Mouse Anti-Human Coagulation Factor XIII-B Subunit Monoclonal Antibodies.

Coagulation factor XIII (FXIII) is an enzyme that strengthens hemostatic clots, and its deficiency can cause life-threatening bleeding. We immunized mice with human plasma-derived FXIII to generate monoclonal antibodies (mAbs) against the B subunit (FXIII-B), which stabilizes the A subunit (FXIII-A) of FXIII, and analyzed their properties. The epitopes of the seven mouse antihuman FXIII-B mAbs obtained were found to be the 3rd, 5th, 6th, 9th, and 10th Sushi domains. One of these mAbs, mAb 5-6C, recognized the 10th Sushi domain and inhibited the fibrin cross-linking reaction without affecting the amine incorporation activity of FXIII. We previously reported that the 10th Sushi domain is the site where FXIII-B binds to fibrin and functions to bring FXIII-A closer to the substrate fibrin. Except for mAb 5-6C, mouse mAbs with high yields were used to measure the amount of FXIII-B antigen by an immunochromatography test (ICT), which showed a high correlation with enzyme-linked immunosorbent assay-obtained results. In addition, we developed a prototype ICT to detect anti-FXIII-B autoantibodies using mAb 1-3C, which showed good results in measuring the amount of FXIII-B antigen. Thus, mouse mAbs may be useful for clinical applications. mAb 5-6C targeting the 10th Sushi domain may also be useful for inhibiting thrombosis progression when humanized as antibody medicines.

The Role of Tissue Factor In Signaling Pathways of Pathological Conditions and Angiogenesis.

Tissue factor (TF) is an integral transmembrane protein associated with the extrinsic coagulation pathway. TF gene expression is regulated in response to inflammatory cytokines, bacterial lipopolysaccharides, and mechanical injuries. TF activity may be affected by phosphorylation of its cytoplasmic domain and alternative splicing. TF acts as the primary initiator of physiological hemostasis, which prevents local bleeding at the injury site. However, aberrant expression of TF, accompanied by the severity of diseases and infections under various pathological conditions, triggers multiple signaling pathways that support thrombosis, angiogenesis, inflammation, and metastasis. Protease-activated receptors (PARs) are central in the downstream signaling pathways of TF. In this study, we have reviewed the TF signaling pathways in different pathological conditions, such as wound injury, asthma, cardiovascular diseases (CVDs), viral infections, cancer and pathological angiogenesis. Angiogenic activities of TF are critical in the repair of wound injuries and aggressive behavior of tumors, which are mainly performed by the actions of vascular endothelial growth factor (VEGF) and hypoxia-inducible factor-1 (HIF1-α). Pro-inflammatory effects of TF have been reported in asthma, CVDs and viral infections, including COVID-19, which result in tissue hypertrophy, inflammation, and thrombosis. TF-FVII induces angiogenesis via clotting-dependent and -independent mechanisms. Clottingdependent angiogenesis is induced via the generation of thrombin and cross-linked fibrin network, which facilitate vessel infiltration and also act as a reservoir for endothelial cells (ECs) growth factors. Expression of TF in tumor cells and ECs triggers clotting-independent angiogenesis through induction of VEGF, urokinase-type plasminogen activator (uPAR), early growth response 1 (EGR1), IL8, and cysteine-rich angiogenic inducer 61 (Cyr61).

A novel method to quantify fibrin–fibrin and fibrin–α2-antiplasmin cross-links in thrombi formed from human trauma patient plasma

BackgroundThe widespread use of the antifibrinolytic agent, tranexamic acid (TXA), interferes with the quantification of fibrinolysis by dynamic laboratory assays such as clot lysis, making it difficult to measure fibrinolysis in many trauma patients. At the final stage of coagulation, factor (F)XIIIa catalyzes the formation of fibrin–fibrin and fibrin–α2-antiplasmin (α2AP) cross-links, which increases clot mechanical strength and resistance to fibrinolysis. ObjectivesHere, we developed a method to quantify fibrin–fibrin and fibrin–α2AP cross-links that avoids the challenges posed by TXA in determining fibrinolytic resistance in conventional assays. MethodsFibrinogen alpha (FGA) chain (FGA–FGA), fibrinogen gamma (FGG) chain (FGG–FGG), and FGA–α2AP cross-links were quantified using liquid chromatography–mass spectrometry (LC–MS) and parallel reaction monitoring in paired plasma samples from trauma patients prefibrinogen and postfibrinogen replacement. Differences in the abundance of cross-links in trauma patients receiving cryoprecipitate (cryo) or fibrinogen concentrate (Fg-C) were analyzed. ResultsThe abundance of cross-links was significantly increased in trauma patients postcryo, but not Fg-C transfusion (P < .0001). The abundance of cross-links was positively correlated with the toughness of individual fibrin fibers, the peak thrombin concentration, and FXIII antigen (P < .05). ConclusionWe have developed a novel method that allows us to quantify fibrin cross-links in trauma patients who have received TXA, providing an indirect measure of fibrinolytic resistance. Using this novel approach, we have avoided the effect of TXA and shown that cryo increases fibrin–fibrin and fibrin–α2AP cross-linking when compared with Fg-C, highlighting the importance of FXIII in clot formation and stability in trauma patients.

Clots reveal anomalous elastic behavior of fiber networks.

The adaptive mechanical properties of soft and fibrous biological materials are relevant to their functionality. The emergence of the macroscopic response of these materials to external stress and intrinsic cell traction from local deformations of their structural components is not well understood. Here, we investigate the nonlinear elastic behavior of blood clots by combining microscopy, rheology, and an elastic network model that incorporates the stretching, bending, and buckling of constituent fibrin fibers. By inhibiting fibrin cross-linking in blood clots, we observe an anomalous softening regime in the macroscopic shear response as well as a reduction in platelet-induced clot contractility. Our model explains these observations from two independent macroscopic measurements in a unified manner, through a single mechanical parameter, the bending stiffness of individual fibers. Supported by experimental evidence, our mechanics-based model provides a framework for predicting and comprehending the nonlinear elastic behavior of blood clots and other active biopolymer networks in general.

Role of factor XIII in ischemic stroke: a key molecule promoting thrombus stabilization and resistance to lysis

BackgroundActive coagulation factor XIII (FXIII) catalyzing crosslinking of fibrin and other hemostatic factors plays a key role in clot stability and lysis. ObjectivesTo evaluate the effect of FXIII inhibition in a mouse model of ischemic stroke (IS) and the role of activated FXIII (FXIIIa) in clot formation and lysis in patients with IS. MethodsA ferric chloride IS murine model was performed before and after administration of a FXIIIa inhibitor (FXIIIinh). Thromboelastometry in human and mice blood was used to evaluate thrombus stiffness and lysis with FXIIIinh. FXIIIa-dependent fibrin crosslinking and lysis with fibrinolytic drugs (tissue plasminogen activator and tenecteplase) were studied on fibrin plates and on thrombi and clotted plasma of patients with IS. Finally, circulating and thrombus FXIIIa were measured in 85 patients with IS. ResultsFXIIIinh administration before stroke induction reduced infarct size, α2-antiplasmin (α2AP) crosslinking, and local microthrombosis, improving motor coordination and fibrinolysis without intracranial bleeds (24 hours). Interestingly, FXIII blockade after stroke also reduced brain damage and neurologic deficit. Thromboelastometry in human/mice blood with FXIIIinh showed delayed clot formation, reduced clot firmness, and shortened tissue plasminogen activator lysis time. FXIIIa fibrin crosslinking increased fibrin density and lysis resistance, which increased further after α2AP addition. FXIIIinh enhanced ex vivo lysis in stroke thrombi and fibrin plates. In patients with IS, thrombus FXIII and α2AP were associated with inflammatory and hemostatic components, and plasma FXIIIa correlated with thrombus α2AP and fibrin. ConclusionOur results suggest a key role of FXIIIa in thrombus stabilization, α2AP crosslinking, and lysis resistance, with a protective effect of FXIIIinh in an IS experimental model.

Sequential-Crosslinking Fibrin Glue for Rapid and Reinforced Hemostasis.

Achieving hemostasis effectively is essential for surgical success and excellent patient outcomes. However, it is challenging to develop hemostatic adhesives that are fast-acting, strongly adherent, long-lasting, and biocompatible for treating hemorrhage. In this study, a sequential crosslinking fibrin glue (SCFG) is developed, of which the first network of the fibrin glue forms in situ within 2s to act as an initial physical barrier and locks the gelatin methacryloyl precursor for tight construction of the second network to enhance wet adhesion and durability for tissues covered with blood. The sequential crosslinking glue can provide large pressures (≈280mmHg of burst pressure), makes strong (38kPa of shear strength) and tough (≈60Jm-2 of interfacial toughness) interfaces with wet tissues, and outperforms commercial hemostatic agents and gelatin methacryloyl. SCFG are demonstrated as an effective and safe sealant to enhance the treatment outcomes of bleeding tissues in rat, rabbit, and pig models. The ultrafast gelation, strong adhesion and durability, excellent compatibility, and easy manufacture of SCFG make it a promising hemostatic adhesive for clinical applications.

Coagulation factor XIII is a critical driver of liver regeneration after partial hepatectomy

BackgroundActivation of coagulation and fibrin deposition in the regenerating liver appears to promote adequate liver regeneration in mice. In humans, perioperative hepatic fibrin deposition is reduced in patients who develop liver dysfunction after partial hepatectomy (PHx), but the mechanism underlying reduced fibrin deposition in these patients is unclear. Methods and ResultsHepatic deposition of cross-linked (ie, stabilized) fibrin was evident in livers of mice after two-thirds PHx. Interestingly, hepatic fibrin cross-linking was dramatically reduced in mice after 90% PHx, an experimental setting of failed liver regeneration, despite similar activation of coagulation after two-thirds or 90% PHx. Likewise, intraoperative activation of coagulation was not reduced in patients who developed liver dysfunction after PHx. Preoperative fibrinogen plasma concentration was not connected to liver dysfunction after PHx in patients. Rather, preoperative and postoperative plasma activity of the transglutaminase coagulation factor (F)XIII, which cross-links fibrin, was lower in patients who developed liver dysfunction than in those who did not. PHx-induced hepatic fibrin cross-linking and hepatic platelet accumulation were significantly reduced in mice lacking the catalytic subunit of FXIII (FXIII−/− mice) after two-thirds PHx. This was coupled with a reduction in both hepatocyte proliferation and liver–to–body weight ratio as well as an apparent reduction in survival after two-thirds PHx in FXIII−/− mice. ConclusionThe results indicate that FXIII is a critical driver of liver regeneration after PHx and suggest that perioperative plasma FXIII activity may predict posthepatectomy liver dysfunction. The results may inform strategies to stabilize proregenerative fibrin during liver resection.

Immunoreactivity of canine, feline, and equine D-dimer with antibodies to human D-dimer.

Commercially available D-dimer assays use antibodies against human D-dimer, with limited sensitivity and specificity data in companion animals. To evaluate the immunoreactivity of D-dimer in plasma of dogs, horses, and cats with commercially available antibodies to human D-dimer. Plasma samples were collected from healthy dogs and horses, and from surplus feline plasma submitted for diagnostic purposes. Descriptive research study. A cross-linked fibrin lysate was prepared from plasma samples, and SDS-PAGE and immunoblotting were performed with a variety of commercially available antibodies to human D-dimer. The selected antibodies demonstrated variable reactivity with D-dimer of each species. The monoclonal antibody DD44 bound canine D-dimer with good specificity and sensitivity, but this antibody did not react with feline or equine D-dimer. The polyclonal antibody D2D bound putative D-dimer in dogs, cats, and horses with good specificity, and higher sensitivity compared to human D-dimer. The variable performance of commercially available human D-dimer assays between species is, in part, because of inter-species variation in D-dimer immunoreactivity. The use of these assays should follow validation studies. Monoclonal antibody DD44 could be a focus for the development of a canine-specific assay.

Chinese expert consensus on D-dimer laboratory testing and clinical application

D-dimer is a degradation product deriving from the plasmin-mediated degradation of cross-linked fibrin. It serves as a biomarker for the activation of coagulation and fibrinolysis, and has been extensively utilized in the diagnosis and treatment of various diseases. However, in recent years, issues related to D-dimer laboratory testing and its clinical application have become increasingly prominent. The lack of standardization in reports has led to confusion in both laboratory testing and clinical application. To address this, the Chinese Society on Thrombosis and Hemostasis brought together experts in the field of thrombosis and hemostasis in China to discuss and develop the 'Chinese Expert Consensus on D-Dimer Laboratory Testing and Clinical Application'. This consensus focuses on laboratory testing methods, quality requirements, performance evaluation, sample processing, analysis interference, result reports, and clinical application of D-dimer. Its aim is to optimize the key issues related to D-dimer testing in laboratories and provide guidance for the appropriate use and accurate interpretation of D-dimer in clinical settings.

HTRS2023.O6B.4 FXIII-mediated cross-linking of hepatic fibrin is a critical driver of platelet accumulation and liver regeneration after partial hepatectomy

HTRS2023.O6B.4 FXIII-mediated cross-linking of hepatic fibrin is a critical driver of platelet accumulation and liver regeneration after partial hepatectomy

A Comprehensive Approach to Analyze the Cell Components of Cerebral Blood Clots.

Cerebral thrombosis, a blood clot in a cerebral artery or vein, is the most common type of cerebral infarction. The study of the cell components of cerebral blood clots is important for diagnosis, treatment, and prognosis. However, the current approaches to studying the cell components of the clots are mainly based on in situ staining, which is unsuitable for the comprehensive study of the cell components because cells are tightly wrapped in the clots. Previous studies have successfully isolated a fibrinolytic enzyme (sFE) from Sipunculus nudus, which can degrade the cross-linked fibrin directly, releasing the cell components. This study established a comprehensive method based on the sFE to study the cell components of cerebral thrombus. This protocol includes clot dissolving, cell releasing, cell staining, and routine blood examination. According to this method, the cell components could be studied quantitatively and qualitatively. The representative results of experiments using this method are shown.

Association of d-dimer levels with in-hospital outcomes among COVID-19 positive patients: a developing country multicenter retrospective cohort.

This multicenter retrospective study was carried out in two tertiary care hospitals in Karachi, Pakistan. The study included adult patients admitted with a laboratory-confirmed coronavirus disease 2019 infection, with at least one measured d-dimer within 24h following admission. Discharged patients were compared with the mortality group for survival analysis. The study population of 813 patients had 68.5% males, with a median age of 57.0 years and 14.0 days of illness. The largest d-dimer elevation was between 0.51-2.00mcg/ml (tertile 2) observed in 332 patients (40.8%), followed by 236 patients (29.2%) having values greater than 5.00mcg/ml (tertile 4). Within 45 days of hospital stay, 230 patients (28.3%) died, with the majority in the ICU (53.9%). On multivariable logistic regression between d-dimer and mortality, the unadjusted (Model 1) had a higher d-dimer category (tertile 3 and tertile 4) associated with a higher risk of death (OR: 2.15; 95% CI: 1.02-4.54, P=0.044) and (OR: 4.74; 95% CI: 2.38-9.46, P<0.001). Adjustment for age, sex, and BMI (Model 2) yields only tertile 4 being significant (OR: 4.27; 95% CI: 2.06-8.86, P<0.001). Higher d-dimer levels were independently associated with a high risk of mortality. The added value of d-dimer in risk stratifying patients for mortality was not affected by invasive ventilation, ICU stays, length of hospital stays, or comorbidities.

Antibodies against non-catalytic B subunit of factor XIII inhibit activation of factor XIII and fibrin crosslinking.

Coagulation factor XIII (FXIII) is a proenzyme of plasma transglutaminase. It comprises two catalytic A subunits (FXIII-A) and two carrier B subunits (FXIII-B). We previously reported that alloantibodies against FXIII-B could promote FXIII clearance in a patient with congenital FXIII-B deficiency who had received infusions of plasma-derived human FXIII (A2B2 heterotetramer). We aimed to investigate whether anti-FXIII-B antibodies affect the catalytic function of FXIII. FXIII activation and fibrin crosslinking were examined in the presence of patient plasma, isolated patient IgG, or rat anti-FXIII-B monoclonal antibodies. Alloantibody levels were increased by repeated infusions of plasma-derived A2B2 heterotetramer, which enhanced binding to the functionally important FXIII-B Sushi domains. The patient plasma strongly inhibited cleavage of the FXIII-A activation peptide, amine incorporation, and fibrin crosslinking in normal plasma. Further, anti-FXIII-B alloantibodies blocked the formation of the complex of FXIII-B with FXIII-A, and fibrinogen. Rat monoclonal antibodies against the 10th Sushi domain of FXIII-B inhibited the incorporation of FXIII-B to fibrin, FXIII activation (i.e., cleavage of FXIII-A activation peptide), and ultimately fibrin crosslinking in normal plasma, independent of their effect on heterotetramer assembly with FXIII-A. Alloantibody binding to the A2B2 heterotetramer blocked the access of thrombin to the FXIII-A cleavage site, as indicated by the reaction of the alloantibodies to the A2B2 heterotetramer and FXIII-B, but not to FXIII-A. Anti-FXIII-B antibodies binding to the A2B2 heterotetramer and FXIII-B inhibited FXIII activation and its crosslinking function despite being directed against its non-catalytic subunit (FXIII-B).

Altered fibrinogen γ-chain cross-linking in mutant fibrinogen-γΔ5 mice drives acute liver injury

BackgroundHepatic deposition of cross-linked fibrin(ogen) occurs alongside platelet accumulation as a hallmark of acetaminophen (APAP)-induced liver injury. ObjectivesWe sought to define the precise role of the fibrinogen γ-chain C-terminal integrin αIIbβ3 binding domain in APAP-induced liver injury. MethodsMice expressing mutant fibrinogen incapable of engaging integrin αIIbβ3 due to a C-terminal fibrinogen γ-chain truncation (mutant fibrinogen-γΔ5 [FibγΔ5] mice) and wild-type mice were challenged with APAP (300 mg/kg, intraperitoneally). ResultsWe observed an altered pattern of fibrin(ogen) deposition in the livers of APAP-challenged FibγΔ5 mice. This led to the unexpected discovery that fibrinogen γ-chain cross-linking was altered in the livers of APAP-challenged FibγΔ5 mice compared with that in wild-type mice, including absence of γ-γ dimer and accumulation of larger molecular weight cross-linked γ-chain complexes. This finding was not unique to the injured liver because activation of coagulation did not produce γ-γ dimer in plasma from FibγΔ5 mice or purified FibγΔ5 fibrinogen. Sanger sequencing predicted that the fibrinogen-γΔ5 γ-polypeptide would terminate at lysine residue 406, but liquid chromatography tandem mass spectrometry analysis revealed that this critical lysine residue was absent in purified fibrinogen-γΔ5 protein. Interestingly, hepatic deposition of this uniquely aberrantly cross-linked fibrin(ogen) in FibγΔ5 mice was associated with exacerbated hepatic injury, an effect not recapitulated by pharmacologic inhibition of integrin αIIbβ3. ConclusionThe results indicate that fibrinogen-γΔ5 lacks critical residues essential to form γ-γ dimer in response to thrombin and suggest that hepatic accumulation of abnormally cross-linked fibrin(ogen) can exacerbate hepatic injury.

Changes in retinal circulation and choroidal thickness in patients with acute myeloid leukemia detected by optical coherence tomography angiography.

To investigate changes in retinal circulation and the choroid in patients with acute myeloid leukemia (AML) in the acute and remission stages, to analyze the correlation between retinal circulation and laboratory parameters, and to assess risk factors associated with leukemic retinopathy. Forty-eight patients (93 eyes) with AML were enrolled and divided into two groups according to fundus examination findings: the retinopathy and no retinopathy groups. Patients underwent eye measurements before treatment and after remission. Macular vessel density (VD), perfusion density (PD), foveal avascular zone (FAZ), and choroidal thickness (ChT) were measured using optical coherence tomography angiography. Patients with healthy eyes were recruited as control participants. Patients with leukemic retinopathy had higher measurements of white blood cells (WBCs), circulating blasts, fibrin degradation products, and cross-linked fibrin degradation products (D-dimer) and a lower hemoglobin (HB) count (p < 0.05). In the acute phase of the disease, the VD and PD were lower and the ChT was thicker in patients with AML than in controls (p < 0.05), irrespective of the presence of leukemic retinopathy; however, the patients were partially recovered in the remission stage. The VD was lower in patients with higher WBC (r = -0.217, p = 0.036), D-dimer (r = -0.279, p = 0.001), fasting blood glucose (FBG) (r = -0.298, p = 0.004) and triglyceride (r = -0.336, p = 0.001) levels. The FAZ area was negatively correlated with HB (r = -0.258, p = 0.012). Patients with AML appear to have subclinical retinal perfusion loss and choroidal thickening in the acute phase of the disease, but this is reversible. Injury to bone marrow function may cause a decrease in retinal perfusion. Leukemic retinopathy is associated with abnormal hematologic parameters and coagulopathy.

The prognostic value of admission D-dimer level in patients with cardiogenic shock after acute myocardial infarction.

Shock is associated with the activation of the coagulation and fibrinolytic system, and D-dimer is the degradation product of cross-linked fibrin. However, the prognostic value of D-dimer in patients with cardiogenic shock (CS) after acute myocardial infarction (AMI) remains unclear. We retrospectively analyzed the data of consecutive patients with CS complicating AMI. The primary endpoint was 30-day mortality and the secondary endpoint was the major adverse cardiovascular events (MACEs) including 30-day all-cause mortality, ventricular tachycardia/ventricular fibrillation, atrioventricular block, gastrointestinal hemorrhage, and non-fatal stroke. Restricted cubic spline (RCS) analyses were performed to assess the association between admission D-dimer and outcomes. A multivariable Cox regression model was performed to identify independent risk factors. The risk predictive potency with D-dimer added to the traditional risk scores was evaluated by C-statistics and the net reclassification index. Among 218 patients with CS complicating AMI, those who died during the 30-day follow-up presented with worse baseline characteristics and laboratory test results, including a higher level of D-dimer. According to the X-tile program result, the continuous plasma D-dimer level was divided into three gradients. The 30-day all-cause mortality in patients with low, medium, and high levels of D-dimer were 22.4, 53.3, and 86.2%, respectively (p < 0.001 for all). The 30-day incidence of MACEs was 46.3, 77.0, and 89.7%, respectively (p < 0.001). In the multivariable Cox regression model, the trilogy of D-dimer level was an independent risk predictor for 30-day mortality (median D-dimer cohort: HR 1.768, 95% CI 0.982-3.183, p = 0.057; high D-dimer cohort: HR 2.602, 95% CI 1.310-5.168, p = 0.006), a similar result was observed in secondary endpoint events (median D-dimer cohort: HR 2.012, 95% CI 1.329-3.044, p = 0.001; high D-dimer cohort: HR 2.543, 95% CI 1.452-4.453, p = 0.001). The RCS analyses suggested non-linear associations of D-dimer with 30-day mortality. The enrollment of D-dimer improved risk discrimination for all-cause death when combined with the traditional CardShock score (C-index: 0.741 vs. 0.756, p difference = 0.004) and the IABP-SHOCK II score (C-index: 0.732 vs. 0.754, p difference = 0.006), and the GRACE score (C-index: 0.679 vs. 0.715, p difference < 0.001). Similar results were acquired after logarithmic transformed D-dimer was included in the risk score. The improvements in reclassification which were calculated as additional net reclassification index were 7.5, 8.6, and 12.8%, respectively. Admission D-dimer level was independently associated with the short-term outcome in patients with CS complicating AMI and addition of D-dimer brought incremental risk prediction value to traditional risk prediction scores.

Cloning of human anti-factor XIII monoclonal antibody dissects mechanisms of polyclonal antibodies in a single patient

BackgroundCoagulation factor XIII (FXIII) consists of 2 A (FXIII-A) and 2 B (FXIII-B) subunits that cross-link and strengthen the hemostatic fibrin thrombus; thus, abnormal bleeding occurs when FXIII is significantly reduced. Autoimmune-acquired FXIII deficiency (AiF13D) is characterized by lethal bleeding secondary to the development of autoantibodies against FXIII. However, since anti-FXIII autoantibodies are polyclonal, the mechanism underlying FXIII dysfunction is unclear. ObjectivesThe objective of this study was to dissect the inhibitory mechanisms of polyclonal anti-FXIII autoantibodies. MethodsIn this study, we prepared the human monoclonal antibodies (hmAbs) from the peripheral blood of an 86-year-old man with AiF13D by using a new complementary DNA cloning method and analyzed the properties of each autoantibody. ResultsSeventeen clones obtained from hmAbs were divided into the following 3 groups: dissociation inhibitors of FXIII-A2B2 (6 clones), assembly inhibitors of FXIII-A2B2 (3 clones), and nonneutralizing/inhibitory hmAbs (8 clones). Dissociation inhibitors strongly inhibited fibrin cross-linking and amine incorporation. Assembly inhibitors extracted FXIII-A from FXIII-A2B2, strongly inhibited binding of FXIII-A to FXIII-B, and activation peptide cleavage. However, the patient’s plasma presented a strong inhibition of A2B2 heterodimer assembly but only a slight inhibition of thrombin-Ca2+-dependent dissociation, suggesting that the assembly inhibitors concealed the effect of dissociation inhibitors in plasma. By contrast, nonneutralizing antibodies had little effect on the function of FXIII, suggesting that nonneutralizing hmAbs (and/or dissociation inhibitors and/or assembly inhibitors) promoted the clearance of FXIII-A from the blood. ConclusionCloning of anti-FXIII autoantibodies enabled us to not only elucidate the mechanism and pathophysiology of AiF13D but also develop a completely new type of anticoagulant.

Elimination of fibrin polymer formation or crosslinking, but not fibrinogen deficiency, is protective against diet‐induced obesity and associated pathologies

BackgroundObesity predisposes individuals to metabolic syndrome, which increases the risk of cardiovascular diseases, non‐alcoholic fatty liver disease (NAFLD), and type 2 diabetes. A pathological manifestation of obesity is the activation of the coagulation system. In turn, extravascular fibrin(ogen) deposits accumulate in adipose tissues and liver. These deposits promote adiposity and downstream sequelae by driving pro‐inflammatory macrophage function through binding the leukocyte integrin receptor αMβ2. ObjectivesAn unresolved question is whether conversion of soluble fibrinogen to a crosslinked fibrin matrix is required to exacerbate obesity‐driven diseases. MethodsHere, fibrinogen-deficient/depleted mice (Fib- or treated with siRNA against fibrinogen [siFga]), mice expressing fibrinogen that cannot polymerize to fibrin (FibAEK), and mice deficient in the fibrin crosslinking transglutaminase factor XIII (FXIII–) were challenged with a high-fat diet (HFD) and compared to mice expressing a mutant form of fibrinogen lacking the αMβ2‐binding domain (Fibγ390-396A). Results and ConclusionsConsistent with prior studies, Fibγ390‐396A mice were significantly protected from increased adiposity, NAFLD, hypercholesterolemia, and diabetes while Fib‐ and siFga‐treated mice gained as much weight and developed obesity‐associated pathologies identical to wildtype mice. FibAEK and FXIII– mice displayed an intermediate phenotype with partial protection from some obesity‐associated pathologies. Results here indicate that fibrin(ogen) lacking αMβ2 binding function offers substantial protection from obesity and associated disease that is partially recapitulated by preventing fibrin polymer formation or crosslinking of the wildtype molecule, but not by reduction or complete elimination of fibrinogen. Finally, these findings support the concept that fibrin polymerization and crosslinking are required for the full implementation of fibrin‐driven inflammation in obesity.