Plasma levels of activated protein C-protein C inhibitor complex in patients with hypercoagulable states

Factors predicting resolution of left ventricular thrombus in different time windows after myocardial infarction

BACKGROUND

Left ventricular thrombus (LVT) is a serious complication after myocardial infarction. However, due to its asymptomatic nature, early detection is challenging. We aimed to explore the differences in clinical correlates of LVT found in acute to subacute and chronic phases of myocardial infarction.

METHODS

We collected data from 153 patients who were diagnosed with LVT after myocardial infarction at the Affiliated Hospital of Qingdao University from January 2013 to December 2022. Baseline information, inflammatory markers, transthoracic echocardiograph (TTE) data and other clinical correlates were collected. Patients were categorized into acute to subacute phase group (< 30 days) and chronic phase group (30 days and after) according to the time at which echocardiograph was performed. The resolution of thrombus within 90 days is regarded as the primary endpoint event. We fitted logistic regression models to relating clinical correlates with phase-specific thrombus resolution.

RESULTS

For acute to subacute phase thrombus patients: C-reactive protein levels (OR: 0.95, 95% CI: 0.918-0.983, p = 0.003) were significantly associated with thrombus resolution. For chronic phase thrombus patients: anticoagulant treatment was associated with 5.717-fold odds of thrombus resolution (OR: 5.717, 95% CI: 1.543-21.18, p = 0.009).

CONCLUSIONS

Higher levels of CRP were associated with lower likelihood of LVT resolution in acute phase myocardial infarction; Anticoagulant therapy is still needed for thrombus in the chronic stage of myocardial infarction.

Serum D-dimer as a potential new biomarker for prognosis in patients with thrombotic thrombocytopenic purpura

Thrombotic thrombocytopenic purpura (TTP) is a life-threatening disease, and its mortality rate is 10% to 20%. However, there are currently only a few markers to predict the prognosis in patients with TTP. We aimed to identify several clinical indices and laboratory parameters for predicting the prognosis of TTP at admission.A single-centre observational cohort study that included patients with TTP from the First Affiliated Hospital of Zhengzhou University in China was conducted from January 1, 2012 to November 30, 2018. The primary outcome was prognosis, including in-hospital mortality, major thromboembolic events, or failure to achieve remission at discharge. We used the random forest method to identify the best set of predictors.Eighty-seven patients with TTP were identified, of whom 12 died during the treatment. The total number of patients within-hospital mortality, major thromboembolic events, and failure to achieve remission at discharge was 58. The machine learning method showed that the D-dimer level was the strongest predictor of the primary outcome. Receiver operating characteristic (ROC) analysis demonstrated that the sensitivity and specificity of the D-dimer level alone for identifying high-risk patients were 78% and 81%, respectively, with an optimum diagnostic cut-off value of 770 ng/mL. The area under the ROC curve (AUC) was 0.80, and the 95% confidence interval (CI) was 0.70 to 0.90.This study found that the D-dimer level exhibited a good predictive ability for prognosis in patients with TTP. These findings may aid in the development of new and intensive treatment strategies to achieve remission among high-risk patients. However, external validation is necessary to confirm the generalizability of our approach across populations and treatment practices.

Effects of Lipid Abnormalities on Arteriosclerosis and Hemostatic Markers in Patients under Hemodialysis

Vascular events caused by arteriosclerosis are the major cause of death in patients under hemodialysis (HD). Arteriosclerosis is associated with lipoprotein abnormalities such as increased serum levels of low-density lipoprotein (LDL), especially of modified LDL (M-LDL) and oxidized LDL (Ox-LDL). We examined the relationship between markers of arteriosclerosis, hemostasis, and lipid metabolism in patients with chronic renal failure, hyperlipidemia, and healthy volunteers. In patients under HD, the serum levels of total cholesterol, LDL, and triglyceride (TG) were decreased, but the serum levels of M-LDL were increased compared to HL and healthy volunteers. In patients with CRF, the serum levels of OxLDL in patients under HD were lower than in those under continuous ambulatory peritoneal dialysis or conservative therapy. The plasma levels of antithrombin and protein C were significantly lower and the plasma levels of thrombomodulin were significantly higher in patients under HD compared to those under conservative therapy. These data show that patients under HD were more in hypercoagulable state than those under conservative therapy. Among patients under HD, only the plasma levels of von Willebrand factor were significantly increased in patients with more than 30 U/L of Ox-LDL compared to those with less than 30 U/L of Ox-LDL. There was no significant difference in the tests of arteriosclerosis among M-LDL values and OxLDL values. These findings suggest that abnormalities of lipid are not the main risk factor for arteriosclerosis disease in patients under HD.

Protein C inhibitor (PCI) binds to phosphatidylserine exposing cells with implications in the phagocytosis of apoptotic cells and activated platelets

Protein C Inhibitor (PCI) is a secreted serine protease inhibitor, belonging to the family of serpins. In addition to activated protein C PCI inactivates several other proteases of the coagulation and fibrinolytic systems, suggesting a regulatory role in hemostasis. Glycosaminoglycans and certain negatively charged phospholipids, like phosphatidylserine, bind to PCI and modulate its activity. Phosphatidylerine (PS) is exposed on the surface of apoptotic cells and known as a phagocytosis marker. We hypothesized that PCI might bind to PS exposed on apoptotic cells and thereby influence their removal by phagocytosis. Using Jurkat T-lymphocytes and U937 myeloid cells, we show here that PCI binds to apoptotic cells to a similar extent at the same sites as Annexin V, but in a different manner as compared to live cells (defined spots on ∼10-30% of cells). PCI dose dependently decreased phagocytosis of apoptotic Jurkat cells by U937 macrophages. Moreover, the phagocytosis of PS exposing, activated platelets by human blood derived monocytes declined in the presence of PCI. In U937 cells the expression of PCI as well as the surface binding of PCI increased with time of phorbol ester treatment/macrophage differentiation. The results of this study suggest a role of PCI not only for the function and/or maturation of macrophages, but also as a negative regulator of apoptotic cell and activated platelets removal.

APC-PCI complex levels for screening of AAA in patients with peripheral atherosclerosis

To evaluate the use of activated protein C-protein C inhibitor (APC-PCI) complex levels for detection of abdominal aortic aneurysm (AAA) in patients with peripheral atherosclerotic disease (PAD). APC-PCI levels and aortic diameter evaluated in 511 PAD patients without previously known AAA followed-up concerning survival for 4.8(0.5) years. AAA was found in 13% of patients. Aortic diameter correlated (r = 0.138; p = 0.002) with APC-PCI levels which were higher (0.40[0.45] vs. 0.30[0.49] μg/l; p = 0.004) in patients with AAA. This difference persisted in multivariate analysis (p = 0.029). A threshold value of APC-PCI ≥0.15 μg/L showed a specificity of 11%, a sensitivity of 97% and a negative predictive value of 96% for an AAA diagnosis. APC-PCI levels were higher in patients with AAA, and showed high sensitivity but low specificity for the diagnosis and can therefore not be considered as a screening tool in PAD patients. An AAA prevalence of 13% in patients with PAD indicates a need for AAA screening within this population.

Urinary proteomics in cardiovascular disease: Achievements, limits and hopes

Cardiovascular disease (CVD) is the major cause of mortality and morbidity worldwide. Diagnosis of CVD and risk stratification of patients with CVD remains challenging despite the availability of a wealth of non-invasive and invasive tests. Clinical proteomics analyses a large number of peptides and proteins in biofluids. For clinical applications, the urinary proteome appears particularly attractive due to the relative low complexity compared with the plasma proteome and the noninvasive collection of urine. In this article, we review the results from pilot studies into urinary proteomics of coronary artery disease and discuss the potential of urinary proteomics in the context of pathogenesis of CVD.

Activated protein C-protein C inhibitor complex in peripheral arterial disease

BACKGROUND

Thrombin activation measured by the levels of the complex between activated protein C (APC) and the protein C inhibitor (PCI) is elevated in several atherosclerotic disorders. The aim of this study was to evaluate whether levels of the APC-PCI complex are related to the prognosis in peripheral arterial disease (PAD). Longitudinal study performed at the Vascular Centre, Malmö University Hospital, Sweden.

METHODS

APC-PCI complex levels were analyzed in 268 consecutive patients hospitalized for PAD and in 42 healthy controls (median age, 74 years). Patients (n = 35) with warfarin treatment less than 4 weeks before APC-PCI sampling were excluded from analysis. Data-based medical records of all 233 remaining patients (median age, 72 [64-79] years) were searched for vascular events such as hospitalization because of atherosclerotic disease, operative or endovascular recanalization of peripheral arteries, transtibial or transfemoral amputation because of PAD, acute coronary syndrome, stroke, or death.

RESULTS

Median duration of follow-up was 16 months (interquartile range, 12-23 months). APC-PCI complex levels were higher in PAD patients than in controls (0.240 [0.180-0.320] microg/L vs. 0.140 [0.190-0.220] microg/L; p < 0.0001) but not associated with an increased risk for death (p = 0.2054) or events during follow-up (p = 0.2850). Independent predictors of future events were low b-hemoglobin (p = 0.0084), high b-leukocytes (p = 0.0034), and history of a previous vascular event (p = 0.0032). Age (p = 0.0286), high p-creatinine (p = 0.0165), and history of a previous event (p = 0.0311) were independent predictors of death.

CONCLUSION

APC-PCI complex levels were higher in PAD patients than in controls, but did not predict the clinical outcome. The effect of a possible prethrombotic state, as reflected in increased APC-PCI levels, on prognosis and severity of atherosclerotic disease has to be further investigated.

Gene expression signatures in the peripheral blood after radiosurgery of human cerebral arteriovenous malformations

PURPOSE

To unravel biological mechanisms potentially resulting in the obliteration process after radiosurgery (RS) of human cerebral arteriovenous malformations (AVMs) by investigating molecular signatures on the transcriptomic level in peripheral blood of patients.

PATIENTS AND METHODS

Venous blood samples were obtained at definite points of time before and after RS. The samples were tested for radiation-induced changes regarding biological markers (mRNA) using cDNA and oligo-microarray technology. The corresponding expression profiles were correlated with clinical data and obliteration signs in radiologic imaging.

RESULTS

The proof of principle that RS outcome can be successfully correlated with transcriptomics of cellular blood components as disease parameter was demonstrated. The authors identified 76 differentially regulated genes (p < 0.001) after RS. Interestingly, in particular genes with known roles in anti-angiogenic and pro-coagulative pathways were identified as potentially relevant. In particularly, the authors found a significant downregulation of neuropilin-2, protein C inhibitor and cyclin-dependent kinase 6. They also found that low pretreatment blood mRNA levels of TLR4 (toll-like receptor 4) and STAT3 (signal transducer and activator of transcription 3) correlated with fast obliteration of AVMs.

CONCLUSION

The authors report on a novel technique for molecular biological analysis of blood from patients with cerebral AVM treated with RS. Differential regulation of genes in peripheral blood was successfully correlated with RS and time to obliteration of AVMs. The identified genes indicate a potential new methodology to monitor RS, which may result in an individualized therapy and optimized follow-up.

Lower incidence of procoagulant abnormalities during follow-up after creation of the Fontan circulation in children

OBJECTIVE

Children who undergo surgery for complex congenital cardiac disease are reported to be at increased thrombotic risk. Our aim was to evaluate long-term changes in the haemostatic system after surgery, to compare markers of activated coagulation in children having surgery with those in a healthy control population, and to relate them to adverse clinical outcome.

PATIENTS AND METHODS

We studied, prior to surgery, the coagulation profiles of a cohort of 28 children admitted for a modified Fontan operation, studying them again after a period of mean follow-up of 9.6 years. Median age at the time of final surgery was 18.5 months, with a range from 12 to 76 months. We compared generation of thrombin, and levels of the activated protein C-protein C inhibitor complex to controls at follow-up. Thrombophilia and clinical outcome were evaluated.

RESULTS

At long-term follow-up, a lower incidence of procoagulant abnormalities was observed compared to that before surgery. Of 27 patients, 3 (11%), but none of 45 controls, had levels of activated protein C-protein C inhibitor complex above the reference range. There were no significant differences in generation of thrombin between patients and controls. No thrombotic events were recorded, and the patients were generally in good clinical condition.

CONCLUSIONS

Overall, haemostasis appeared to be in balance, and less prothrombotic, after surgery. A subset of the cohort did show indications of activated coagulation. The current therapeutic approach seems to be sufficient to protect the majority of patient. New tests of global coagulation, nonetheless, may be helpful in improving identification of individuals at increased thrombotic risk.

Plasma markers of activated hemostasis in the early diagnosis of acute coronary syndromes

BACKGROUND

Because acute coronary syndromes (ACS) are caused by intracoronary thrombosis, plasma markers of coagulation have relevance for early diagnosis.

AIMS AND OBJECTIVES

To provide a critical review of these studies and specific attempts to close the diagnostic time gap left by traditional plasma markers of heart injury.

METHODS

Studies of ACS patients, with at least one control group, were included when blood samples were taken within 24 h after first symptoms prior to medication or intervention. Special attention was paid to studies reporting diagnostic performance, or combination of several markers into a single diagnostic index.

RESULTS

Markers with short plasma half-life (FPA, TAT, etc.) reflect ongoing thrombosis and may identify patients at increased risk. Markers with longer half-life (F1+2, D-Dimer, etc.) may be more useful to indicate a single acute thrombotic event. However, results are highly variable and depend on sampling time, clot property, degree of coronary obstruction and physiological condition. Early diagnostic performance of hemostatic markers was poor even when combined with heart injury markers.

CONCLUSIONS

Early measurement of hemostatic plasma markers in ACS patients provides pathophysiological information and may be helpful in risk stratification or to monitor anticoagulant therapy, but does not seem useful in routine clinical diagnosis of ACS.

Characterization of a novel human protein C inhibitor (PCI) gene transgenic mouse useful for studying the role of PCI in physiological and pathological conditions

In humans, protein C inhibitor (PCI) is expressed in various tissues and present in many body fluids including plasma and seminal fluid. In rodents, PCI is expressed in reproductive organs only and is absent in plasma. In this study, we characterized the tissue expression and physiological role of PCI in novel human PCI gene transgenic (TG) mice. Northern blot and immunohistochemical analyses demonstrated that human PCI is expressed in liver hepatocytes, renal epithelial cells as well as heart, brain and reproductive organs of the TG mice. This PCI tissue distribution is similar to that found in humans. PCI in plasma of TG mice showed the same immunological and functional properties as human plasma PCI. Next, we evaluated the effect of PCI on coagulation, inflammation and tissue damage in lipopolysaccharide-treated TG mice. The results suggested that PCI efficiently inhibits not only the anticoagulant and anti-inflammatory activities of exogenously injected human activated protein C (APC) but also that of endogenously produced APC in mice with endotoxemia. These findings suggest that PCI exerts a procoagulant and proinflammatory effect by inhibiting APC. We believe our results also show how useful these TG mice may be for assessing the therapeutic effect of human APC in vivo and for evaluating the role of PCI in human physiological and pathological conditions.

Chronic dialysis patients have high risk for pulmonary embolism

Pulmonary embolism has been considered uncommon in chronic dialysis patients, but has not been adequately studied in a large population. In the US Renal Data System (USRDS), 76,718 patients presenting with end-stage renal disease (ESRD) between January 1, 1996, and December 31, 1996, were analyzed in an historical cohort study. The outcome was hospitalizations with a primary discharge diagnosis of pulmonary embolism (International Classification of Diseases, Ninth Revision code 415.1x) occurring within 1 year of the first ESRD treatment and excluding those occurring after renal transplantation. For dialysis patients, hospitalization rates for pulmonary embolism were obtained from the hospitalization section of the 1999 USRDS. For the general population, hospitalization rates for pulmonary embolism were obtained from the National Hospital Discharge Survey for 1996. Comorbidities from the Medical Evidence Form (Centers for Medicare and Medicaid Services, previously known as the Health Care Financing Administration; form 2728) were used to generate approximated stratified models of adjusted incidence ratios for pulmonary embolism (comorbidities could not be stratified for the general population). In 1996, the overall incidence rate of pulmonary embolism was 149.90/100,000 dialysis patients compared with 24.62/100,000 persons in the US population, with an age-adjusted incidence ratio of 2.34 in dialysis patients. Younger dialysis patients had the greatest relative risk for pulmonary embolism. The age-adjusted incidence ratio of pulmonary embolism after excluding dialysis patients with known risk factors for pulmonary embolism was 2.11. Ninety-five percent confidence intervals for all age categories in both models were statistically significant. Chronic dialysis patients have high risk for pulmonary embolism, independent of comorbidity.

Copper inhibits activated protein C: protective effect of human albumin and an analogue of its high-affinity copper-binding site, d-DAHK

Activated protein C (APC) is useful in the treatment of sepsis. Ischemia and acidosis, which often accompany sepsis, cause the release of copper from loosely bound sites. We investigated (i) whether physiological concentrations of copper inhibit APC anticoagulant activity and (ii) if any copper-induced APC inhibition is reversible by human serum albumin (HSA) or a high-affinity copper-binding analogue of the human albumin N-terminus, d-Asp-d-Ala-d-His-d-Lys (d-DAHK). APC activity after 30 min of incubation with CuCl2 (10 microM) was decreased 26% below baseline. HSA, both alone and when combined with various ratios of CuCl2, increased APC activity significantly above baseline. d-DAHK alone and 2:1 and 4:1 ratios of d-DAHK:CuCl2 also increased APC activity. APC contained 1.4 microM copper, which helps explain the increased APC activity with HSA and d-DAHK alone. These in vitro results indicate that copper inhibits APC activity and that albumin and d-DAHK reverse the copper-induced APC deactivation.

A new method to measure plasma levels of activated protein C in complex with protein C inhibitor in patients with acute coronary syndromes

Our newly devised immunofluorometric sandwich assay for measuring plasma concentrations of activated protein C (APC) in complex with protein C inhibitor (PCI) was compared with testing for conventional markers of myocardial damage CKMB (creatine kinase MB), TNI (troponin I) and hypercoagulability (D-dimer, TAT) in 76 patients with suspected myocardial infarction (MI). APC-PCI complex levels in samples drawn on admission did not correlate with CKMB in the simultaneously drawn sample but correlated closely with maximal CKMB, which reflects MI size (r = 0.52). The areas under the receiver operating characteristics (ROC) curves calculated for the APC-PCI complex results obtained upon admission did not differ significantly from the corresponding values for CKMB, TNI or TAT. Our results show that in patients at risk for MI, the APC-PCI concentration is a sensitive and independent marker that can identify a subgroup of MI patients with normal CKMB but an increased APC-PCI level upon admission. It remains to be determined whether these patients would benefit from early intensive anticoagulant treatment.

New aspects in the pathogenesis and treatment of thrombotic thrombocytopenic purpura and hemolytic uremic syndrome

The thrombotic microangiopathy (TM) syndromes, thrombotic thrombocytopenic purpura and the hemolytic uremic syndrome, are a rare and heterogeneous group of disorders characterized by widespread microvascular thrombosis and end organ injury. Decades of descriptive studies have defined clinical subsets of TM syndromes by clinical and laboratory features. Despite many advances, however, progress towards understanding of the etiology and pathogenesis of TM disorders remains limited. The rarity of occurrence and lack of natural animal models of TM syndromes have hampered progress in experimental and clinical studies. Treatment remains essentially empirical and options are limited. However, recent advances in the genetic and molecular understanding of subsets of TM disorders and the development of relevant animal models offer new resources to explore the pathogenic mechanisms. With these new advances more effective and individualized treatments for TM syndromes can be developed.