IgG deficiency and expansion of CTG repeats in myotonic dystrophy

Objectives

Expansion of CTG repeats in myotonic dystrophy (DM1) alters the regulated expression of numerous genes. It is considered to explain the major clinical features of DM1. IgG deficiency is common in DM1 and is due to altered FcRn-related hypercatabolism. We hypothesized that the IgG catabolic rate is correlated with CTG repeat expansion.

Methods

Correlations between serum immunoglobulin levels, peripheral lymphocyte subset counts and CTG repeat numbers were performed in 52 DM1 patients.

Results

Serum IgG and IgG1 levels were below the normal limit respectively in 54% and 72% of patients. Increasing CTG repeat numbers were significantly correlated with decreasing serum IgG and IgG1 levels, and with decreasing CD3⁺ T-cell and CD3⁺-CD8⁺ cell counts. An abnormal immunoglobulin profile at protein electrophoresis was found in 4 patients.

Conclusion

We conclude that the catabolic rate of IgG is linked to expanded CTG repeats, possibly involving an altered immune response.     

Prevalence and significance of anti-prothrombin (aPT) antibodies in patients with Lupus Anticoagulant (LA)

Objective

Anti-prothrombin (aPT) antibodies have been found in Lupus Anticoagulant (LA) positive patients. Their prevalence and relative contribution to thromboembolic risk in LA-positive patients is not well defined. The aim of this study was to determine their presence and association with thromboembolic events in a large series of patients with confirmed LA.

Methods

Plasma from LA-positive patients was collected at Thrombosis Centers and sent to a reference central laboratory for confirmation. Positive plasma was tested using home-made ELISA for the presence of aPT and anti-β₂GPI antibodies.

Results

LA was confirmed in 231 patients. Sixty-one of 231 (26%, 95%CI 22-33) LA positive subjects were positive for IgG aPT and 62 (27%, 95% CI 21-33) were positive for IgM aPT antibodies. Clinical features of Antiphospholipid Syndrome (APS) were not associated with the presence of IgG aPT [43 APS in 61 (70%) positive and 109 APS in 170 (64%) negative IgG aPT subjects, p = ns] or IgM aPT. Rate of positivity of IgG and IgM aβ₂GPI was significantly higher than that of IgG and IgM aPT. Clinical events accounting for APS occurred in 97 of 130 (75%) IgG aβ₂GPI positive and in 55 of 101 (54%) IgG aβ₂GPI negative patients (OR 2.4, 95% CI 1.4 to 4.3, p = 0.002). No significant association with clinical events in patients positive for both IgG aPT and IgG aβ₂GPI as compared to those positive for one or another test was found. When patients negative for both IgG aPT and IgG aβ₂GPI (LA positive only) were compared with remaining patients, a significantly lower association with clinical events was found (OR = 0.4, 95% CI: 0.2 to 0.7, p = 0.004).

Conclusions

As compared to IgG aβ₂GPI, the prevalence of IgG aPT in patients with LA is significantly lower and not associated with the clinical features of APS.     

Use of the Delphi method to facilitate antithrombotics prescription during pregnancy

Introduction

Management of pregnant women at risk for venous thromboembolism (VTE) remains complex. Guidelines do not definitively fix optimal strategies due to limited trial data. Our objective was to build an easy-to-use tool allowing individualised, risk-adapted prophylaxis.

Materials and Methods

A Delphi exercise was conducted to collect 19 French experts’ opinions on pregnancy-related VTE.

Results

Experts with an active interest in clinical research and care of VTE and placental vascular complications were selected. The risk score was classified by an anonymous computer vote. A scoring system for VTE risk in pregnant women was developed, each score being associated with a specific treatment: graduated elastic compression stockings, aspirin, prophylactic Low Molecular Weight Heparin (LMWH: variable durations), or adjusted-dose of LMWH through pregnancy and postpartum.

Conclusions

Our simple consensual scoring system offers an individual estimation of thrombosis risk during pregnancy together with its related therapeutic strategy, in accordance with most of the new international recommendations. The accuracy of our individual risk score-based therapeutic guidance is currently being prospectively evaluated in a multicenter trial (Clinicaltrials.gov registry no: NCT00745212).     

A novel ELISA system for simultaneous detection of six subclasses of anti-phospholipid antibodies for prediction of thrombotic complications among SLE patients

Background

Anti-phospholipid antibodies (aPLs) are frequently associated with arterial and/or venous thromboembolic complications and recurrent fetal loss in patients with systemic lupus erythematosus (SLE). We recently reported that the clinical picture of SLE apparently depends on subclasses of aPLs in the patient’s sera, but the contribution of each subclass remains uncertain.

Methods

We newly developed an ELISA system for simultaneous detection of six specific categories of aPLs: anti-cardiolipin (aCL), anti-β₂-glycoprotein I (aβ₂GPI), anti-cardiolipin/β₂-glycoprotein I (aCL/β₂GPI), anti-phosphatidylserine (aPS), anti-prothrombin (aPT), and anti-phosphatidylserine/prothrombin (aPS/PT). They were measured in 331 patients with SLE including 63 patients with arterial thromboembolic complications, 64 with venous thromboembolic complications, and 43 with recurrent fetal loss. Lupus anticoagulant (LA) activity in their plasma was measured according to the guidelines recommended by the Subcommittee on Lupus Anticoagulant/Phospholipid-Dependent Antibodies.

Results

Multivariate logistic analysis revealed that the concentration of aPS/PT was most closely associated with arterial thrombosis. In contrast, the concentration of aβ₂GPI was most closely related to venous thrombosis. Furthermore, both aCL/β₂GPI and aPS/PT were independently associated with episodes of recurrent fetal loss. Regarding the relation between APLs and LA activity, aPS/PT, followed by aβ₂GPI and aPT, showed the closest association with the presence of LA activity.

Conclusions

Anti-phospholipid syndrome in patients with SLE can be classified by antigenic specificities of their aPLs as to their susceptibility to arterial and/or venous thromboembolic complications or obstetric complications.     

Anti-prothrombin antibodies are associated with thrombosis in children

Introduction

This investigation aimed to evaluate thrombotic risk factors in children, with special reference to autoantibodies against prothrombin and protein S.

Materials and methods

We studied 57 consecutive Swedish children and adolescents referred with a radiologically confirmed acute thrombotic event. Clinical data were collected and a thrombophilia investigation was performed, including analysis of autoantibodies against protein S (anti-PS) and prothrombin (anti-PT). The anti-PS and anti-PT autoantibodies were also investigated in sera from 47 healthy controls. Detection of autoantibodies was performed by quantitative enzyme-linked immunosorbent assays.

Results

Results for anti-PT antibodies were positive in 21% (12/57) of the patients and 2.1% (1/47) of the controls (OR 12.0, 95% CI 1.7-534; p = 0.005). Seven percent (4/57) of the patients and 2.1% (1/47) of the controls were positive for anti-PS antibodies (OR 3.4, 95% CI 0.3-174; p > 0.30). The FV G1691A mutation was found in 25% (14/57), and 44% (25/57) had 2 or more prothrombotic risk factors. Sixty percent (34/57) of the thrombosis patients were female. Peaks in frequency of thromboembolic events were found in the neonatal and the adolescent periods. Fifty-three percent (30/57) had thrombosis in the lower venous system. Associated clinical conditions occurred in 91% (52/57): systemic illness in 31% (18/57), infections in 26% (15/57), and oral contraceptive use in 25% (14/57). Four percent (2/57) had no apparent clinical or prothrombotic risk factors.

Conclusions

This study suggests that anti-PT autoantibodies may be common risk factors for thrombosis in children, and it confirms the multifactorial nature of pediatric thrombosis.     

Anti-phospholipid antibodies contribute to arteriosclerosis in patients with systemic lupus erythematosus through induction of tissue factor expression and cytokine production from peripheral blood mononuclear cells

Introduction

In systemic lupus erythematosus (SLE) patients, the prevalence of arteriosclerosis obliterans (ASO) is high despite a lack of common risk factors for ASO. The main objective of this study was to investigate a possible direct role of anti-phospholipid antibodies (aPLs), which are frequently detected in SLE patients, in the pathogenesis of ASO.

Materials and Methods

We examined tissue factor (TF) expression on the monocyte surface by flow cytometric analysis in 89 SLE patients with or without ASO and/or aPLs and studied the in vitro effect of purified IgG fractions from plasma of SLE patients or normal healthy volunteers (aPLs(+) IgG, n = 8; aPLs(−) IgG, n = 6; Normal IgG, n = 6) on the expression of TF and production of TNF-α and IL-1β in healthy peripheral blood mononuclear cells (PBMCs) or isolated monocytes.

Results

We confirmed that high expression of monocyte TF was strongly associated with the prevalence of ASO and the presence of aPLs. Treatments of PBMCs with aPLs(−) IgG or normal IgG did not significantly increase expression of TF, TNF-α, and IL-1β messenger RNA (mRNA) and the production of TNF-α and IL-1β. However, stimulation of PBMCs with aPLs(+) IgG caused significant increase in expression of TF, TNF-α, and IL-1β mRNA. Moreover, aPLs(+) IgG stimulated PBMCs and significantly enhanced the production of TNF-α and IL-1β.

Conclusion

These results suggest that IgG-aPLs cause persistently high TF expression and inflammatory cytokine production by interacting with peripheral blood monocytes and lymphocytes, which may be an important mechanism in the pathogenesis of ASO peculiar to SLE patients.     

Suicide verdicts as opposed to accidental deaths in substance-related fatalities (UK, 2001-2007)

Background

Substance-related deaths account for a great number of suicides.

Aim

To investigate levels and characteristics of suicide verdicts, as opposed to accidental deaths, in substance misusers.

Methods

Psychological autopsy study of cases from the UK National Programme on Substance Abuse Deaths (np-SAD) during the period 2001-2007.

Results

Between January 2001 and December 2007, 2108 suicides were reported to the np-SAD. Typical suicide victims were White and older than 50 (respectively 95% and 41% of cases). Medications, especially antidepressants (44%), were prescribed to 87% of victims. Significantly fewer suicide victims than controls presented positive blood toxicological results for illicit drugs (namely: cocaine, heroin, amphetamines, ecstasy-type drugs, cannabis, and GHB/GBL) and alcohol.

Conclusions

Suicide prevention programmes should devote specific attention to deaths among substance misusers who are at high risk of fatal intentional self-harm. Specific characteristics distinguish those at risk; caregivers should be better educated as to what these factors are. Limitations of the current study included lack of provision of comprehensive information relating to the victims' psychosocial variables. Furthermore, no differentiation between different classes of antidepressants in terms of involvement in suicide was here provided.     

Patients with primary antiphospholipid antibody syndrome and without associated vascular risk factors present a normal endothelial function

Introduction

Primary antiphospholipid antibody syndrome (PAPS) is characterized by venous or arterial thrombosis and positive antiphospholipid antibodies. It is controversial whether PAPS patients have early atherosclerosis. Endothelial dysfunction is an early event in the natural history of atherosclerosis. Aim of our study was to compare endothelial function of patients with PAPS and no associated risk factors with that of age- and sex-matched controls.

Materials and Methods

Patients with PAPS, carefully selected to exclude all known risk factors for cardiovascular diseases, estrogen therapy, pregnancy, intake of drugs affecting endothelial function, vitamins or antioxidants, were included in a case-control study. Controls were age- (± 5 years) and sex-matched subjects with the same exclusion criteria but without PAPS. Flow-mediated dilation of the brachial artery and some plasmatic markers of endothelial and platelet activation were measured. Measures are expressed as mean±SEM.

Results

Twenty cases (mean age 42 ± 4.0 years, 11 females) and 39 controls (mean age 41 ± 2.9, 22 females) were studied. FMD was 5.7 ± 0.8% in cases (95% CI: 4.1 to 7.3) and 6.8 ± 0.5% (5.7 to 7.9) in controls (p = NS). Plasma von Willebrand factor was 128 ± 11.3% and 134.2 ± 16.1% in cases and controls, respectively (p = NS). Soluble P-selectin and soluble CD40L were 94.1 ± 4.9 ng/ml and 0.7 ± 0.1 ng/ml in cases and 87.7 ± 4.0 ng/ml and 1.0 ± 0.2 in controls, respectively (p = NS). In a substudy, circulating progenitor and mature endothelial cells were comparable between the two groups.

Conclusions

Endothelial function in patients with PAPS and no associated risk factors is similar to that of age- and sex- matched controls. These data suggest that the alterations leading to thrombosis in PAPS concern primarily the clotting system.     

Prediction of the therapeutic index of marketed anti-coagulants and anti-platelet agents by guinea pig models of thrombosis and hemostasis

Introduction

Animal models of thrombosis and hemostasis are critical for target validation in pharmaceutical research. Guinea pig haemostatic mechanisms, such as the platelet thrombin receptor repertoire, resemble those of humans. Measuring the performance characteristics of marketed antithrombotic drugs in guinea pig models is a key to predicting therapeutic indices of new agents. The goal of the current study was to benchmark representative marketed drugs in thrombosis and hemostasis models in guinea pigs.

Methods

Effects of the cyclooxygenase inhibitor, aspirin, the P2Y₁₂ antagonist, clopidogrel, the glycoprotein IIb/IIIa inhibitor, tirofiban, and the direct thrombin inhibitors, argatroban and hirudin, were evaluated in this study. Antithrombotic agents were tested in FeCl₃-induced carotid artery thrombosis and arterio-venous shunt thrombosis models. Haemostatic effects of drugs were evaluated in cuticle and renal bleeding models. Ex vivo measurements of platelet function and coagulation inhibition were performed to benchmark preclinical doses of each agent to those used clinically.

Results

The overall rank-order of potency in thrombosis models based on per cent of vessels occluded, average carotid blood flow, and thrombus weight was aspirin = argatroban = tirofiban < hirudin = clopidogrel. In bleeding models, the rank order was: aspirin < clopidogrel = argatroban = tirofiban < hirudin.

Conclusion

This characterization of representative drugs from two important classes of anti-coagulant and anti-platelet agents in efficacy and bleeding models in guinea pigs provides a reference point for evaluation of new antithrombotic agents.     

Is quarantine related to immediate negative psychological consequences during the 2009 H1N1 epidemic?

Objective

To investigate whether being quarantined to contain H1N1 flu transmission is related to immediate negative psychological consequences or not.

Methods

Immediate psychological consequences were evaluated with the 20-item Self-Report Questionnaire (SRQ-20) and the Impact of Event Scale-Revised (IES-R) among 419 undergraduate students (176 being quarantined and 243 being nonquarantined).

Results

No significant difference was found between the quarantined group and the nonquarantined group for IES-R screening-positive rate or SRQ-20 screening-positive rate. Multinomial logistic regression analyses indicated that dissatisfaction with control measures was the significant predictor of both SRQ-20 positive screening (OR=2.22) and IES-R positive screening (OR=2.22).

Conclusion

These results are consistent with the conclusion that quarantine does not have negative psychological effects under these circumstances.     

Heparin attenuates lipopolysaccharide-induced acute lung injury by inhibiting nitric oxide synthase and TGF-β/Smad signaling pathway

Introduction

Heparin, a potent blood anticoagulant, has been shown to exert a variety of pharmacological activities. The purpose of this study was to investigate whether heparin has a beneficial effect on lipopolysaccharide (LPS)-induced acute lung injury (ALI) in rats and to further explore the possible underlying mechanisms.

Materials and methods

Adult Sprague-Dawley rats were randomly assigned into the control, heparin, LPS, and LPS plus heparin groups. ALI was induced by intratracheal instillation of LPS at a dose of 1 mg/kg. Rats in the LPS plus heparin group were intravenously received 50 U/ kg heparin every 1 h after the induction of ALI.

Results

We found that heparin significantly improved LPS-induced lung pathological changes, inhibited myeloperoxidase (MPO) activity, and reduced malondialdehyde (MDA) level and lung wet/dry weight ratio. Heparin also inhibited the release of tumor necrosis factor (TNF)-α and interleukin (IL)-6, and markedly decreased the expression of inducible nitric oxide synthase (iNOS) in lung tissues and thus prevented nitric oxide (NO) release in response to LPS challenge. Additionally, heparin decreased the expression of transforming growth factor-β1 (TGF-β1), p-Smad 2, and p-Smad 3, which are all important molecules of the TGF-β1/Smad signaling pathway.

Conclusions

Heparin significantly ameliorated the lung injury induced by LPS in rats via the inhibition of nitric oxide synthase expression and the TGF-β/Smad pathway. Heparin may be a potential therapeutic reagent for treating ALI in the future.     

Determination of alpha-2-macroglobulin complexes by a new immuno-activity assay

Introduction

Alpha-2-macroglobulin (α₂M) is a broad specificity protease inhibitor which impacts several hemostatic pathways. Selective detection of various α₂M complexes may be useful to define markers for the status of different hemostatic components. We present proof of principle for a novel assay to quantitatively measure α₂M in complex with a variety of hemostatic factors.

Materials and Methods

The assay makes use of the fact that α₂M entraps proteases within a molecular “cage”, leaving them inaccessible to macromolecular substrates while retaining functionality against small synthetic substrates. Wells coated with anti-α₂M antibodies were used to isolate the complexes from buffer or plasma, followed by detection of specific proteases with chromogenic substrates. Macromolecular inhibitors were added to eliminate signal from any unbound proteases.

Results

Calibration curves constructed with purified protease-α₂M complexes were sigmoidal in nature, as is typical with immuno-assays. The specificity of signal production was confirmed with inhibitors that target either free protease, or both free and α₂M-bound protease. The detection range of the assay was dependent on the protease being measured, and the surrounding matrix. Interference in detection of complexes in plasma was found to be caused, in part, by free α₂M. Thrombin-α₂M complexes were quantified in adult and newborn plasma following induction of thrombin generation and found to be significantly higher in adults, likely due to higher prothrombin levels.

Conclusions

This assay provides a versatile platform method for quantification of multiple protease-α₂M complexes. It may prove useful for mechanistic in vitro studies of hemostatic pathways, and potentially for clinical applications.     

Fibrin clot properties in women heterozygous for factor V Leiden mutation: Effects of oral contraceptives

Introduction

Oral contraceptives (OC) in the presence of factor V Leiden mutation (FVL) markedly increase the risk of venous thromboembolism (VTE). Little is known about the OC and FVL-related alterations in fibrin clot properties.

Subjects and Methods

Plasma fibrin clot permeability (K_s) and efficiency of lysis, reflected by clot lysis time (CLT) and the rate of D-dimer release from clots (D-D_rate) induced by recombinant tissue plasminogen activator (tPA) were determined in 25 women with a family history of VTE who were heterozygous for FVL [FVL(+/−) - twice, on third-generation OC and after their discontinuation. Female non-carriers of FVL, matched for demographics, using OC and after their discontinuation served as controls (n = 25). All participants had no personal history of VTE.

Results

OC discontinuation in FVL(+/−) women resulted in shortened CLT (− 9%), and increased K_s (+ 4%) and D-D_rate (+ 1.4%; all p < 0.01). Alterations in fibrin clot properties were associated with decreased prothrombin fragments 1 + 2 (F1 + 2) (− 8%), plasminogen activator inhibitor-1 (PAI-1) antigen (− 11%), and thrombin activatable fibrinolysis inhibitor (TAFI) activity (− 20%; all p < 0.01). During OC use FVL(+/−) carriers compared with non-carriers had higher platelet count, activity of PAI-1, TAFI, and tPA, as well as prolonged CLT and higher D-D_max, along with lower D-D_rate and K_s. Multiple regression analysis adjusted for fibrinogen and age, showed that PAI-1 antigen and TAFI activity independently predicted CLT in FVL(+/−) women on OC.

Conclusion

FVL(+/−) is associated with hypofibrinolysis in apparently healthy women and third-generation OC administration unfavorably alters plasma clot characteristics in female FVL(+/−) carriers with a family history of thrombotic events.     

Interpretation and management of INR results: A case history based survey in 13 countries

Introduction

Standardisation of treatment with vitamin K antagonists (VKAs) is still an issue after 60 years of use. The study aimed to explore aspects of VKA monitoring in primary and secondary care.

Methods

Two case histories were distributed to physicians in 13 countries. Case history A focused on a patient with atrial fibrillation on stable anticoagulation (latest INR 2.3). Physicians were asked about frequency of INR measurement, when to change the VKA dose, and the patient's annual risk of ischemic stroke and bleeding. Case history B focused on a patient with an unexpected INR of 4.8, asking for the patient's 48-hour bleeding risk, the immediate dose reduction and time until a repeat INR.

Results

Altogether, 3016 physicians responded (response rate 8 - 38%), of which 82% were from primary care and 18% from secondary care. Answers varied substantially within and between countries regardless of level of care and VKA used. Median number of weeks between INR measurements was 4 - 6 weeks. Median threshold INR for increasing or decreasing the VKA dose was 1.9 and 3.1, respectively. Risk of ischemic stroke and bleeding were overestimated 2 - 3 times. In case history B, the median dose reduction the two first days was 75% for GPs and 55% for specialists, irrespective of estimates of bleeding risk; with one week to a repeat INR.

Conclusion

Variation in VKA monitoring is substantial implying clinical consequences. Guidelines seem either unknown or may be considered impracticable. Further efforts towards standardisation of VKA management are needed.     

A comparative study of antithrombotic and antiplatelet activities of different fucoidans from Laminaria japonica

Introduction

Fucoidans extracted from brown algae represent an intriguing group of natural fucose-enriched sulfated polysaccharide, with excellent anticoagulant, antimetastatic, antiangiogenic and anti-inflammatory activities. In the present study, we compared antithrombotic activities of four fucoidan fractions with different molecular weight and sulfated ester content from Laminaria japonica in an electrical induced arterial thrombosis and their potential mechanism underlying such activity.

Results and Conclusions

In vivo middle molecular weight (MMW) fucoidan fractions with molecular weight about 28000 and 35000 exhibited better antithrombotic activity in electrical induced arterial thrombosis than low molecular weight (LMW) fucoidan LF1 and LF2 (Mw 7600 and 3900). Inhibition of arterial thrombosis occurred at dose of 0.1-0.25 mg/kg for MMW fucoidans, accompanied with moderate anticoagulant activity and significant decrease of whole blood viscosity and hematocrit. The antithrombotic effects of MMW Fucoidans might be related with promotion of TFPI content and decrease of TXB2 content, without affecting platelet aggregation and 6-keto-PGF1α content in vivo. In contrast, LMW fucoidans showed a correlation among anticoagulant, antiplatelet and antithrombotic effects in vivo. Antithrombotic action of LF1 and LF2 required high dose of 2.5-10 mg/kg, concomitantly with anticoagulant activity and specific inhibition of platelet aggregation in vivo. Their antithrombotic effect might be related to their promotion of TFPI and 6-keto-PGF1α, down regulation of TXB2, without affecting hemorheology. These findings suggested that fucoidan fractions with different molecular weight acted on the antithrombotic action by different mechanism. By comparison, highly sulfated fucoidan LF2 with molecular weight of 3900 seemed to be a more suitable choice of antithrombotic drug for its antithrombotic activity accompanied with specific inhibitory activity on platelet aggregation, low anticoagulant activity and low hemorrhagic risk in vivo.     

Thrombomodulin-dependent effect of factor VLeiden mutation on factor XIII activation

Introduction

Factor V Leiden mutation (FV_Leiden) is associated with impaired down-regulation of activated FV procoagulant activity and loss of FV anticoagulant function that result in an increased risk of venous thromboembolism. As the downstream effects of FV_Leiden on clot formation and fibrinolyis have only partially been revealed, we investigated its effect on the activation of factor XIII (FXIII) and the cross-linking of fibrin.

Methods

In the plasma samples of fifteen healthy individuals with known FV genotypes coagulation was initiated by recombinant human tissue factor and phospholipids with or without recombinant human thrombomodulin (rhTM). FV deficient plasma supplemented with purified wild type FV or FV_Leiden were also investigated. Clots were recovered and analyzed by SDS-PAGE and quantitative densitometric evaluation of Western blots.

Results

rhTM considerably delayed the activation of FXIII in the plasma from FV wild type individuals. This effect of rhTM was significantly impaired in the plasma from FV_Leiden carriers. The results were confirmed in experiments with FV deficient plasma supplemented by FV prepared from wild type individuals or FV_Leiden homozygotes. Fibrin γ-chain dimerization was also considerably delayed by rhTM in plasma samples from individuals without Leiden mutation, but not in plasma samples from FV_Leiden heterozygotes or homozygotes. The difference between heterozygotes and homozygotes was not statistically significant.

Conclusion

The highly diminished delaying effect of TM on FXIII activation and on the cross-linking of fibrin in FV_Leiden carriers might represent a novel mechanism contributing to the increased thrombosis risk of these individuals.     

Expression of protein C (PC), protein S (PS) and thrombomodulin (TM) in human colorectal cancer

Introduction

Colorectal cancer (CRC) is often complicated by thromboembolic episodes. It has been recognized that blood coagulation proteins play a role in cancer progression. An important inhibitory mechanism is provided by the protein C (PC) system consisting of PC, protein S (PS) and thrombomodulin (TM). Recently, novel biological activities have been ascribed to the PC system that do not relate to their hemostatic functions, eg. in angiogenesis, apoptosis and inflammation.

Objectives

The purpose of the study was to elucidate the solid phase interactions between CRC tissue and components of the PC system that may contribute to tumor progression.

Material and methods

CRC tissues were obtained at surgical resection during treatment of 66 patients. Immunohistochemical studies were performed using polyclonal antibodies against PC, PS and TM. A semiquantitative analysis of the protein expression was also performed.

Results

Weak expression of PC was observed in cancer cells of two-thirds of the specimens examined, while in 3/66 cases there was no staining for PC in cancer cells. One fourth of CRCs exhibited strong expression of PC. The presence of PS was demonstrated in 64/66 cases of CRC. However, its expression was irregular in terms of intensity of staining and percentage of cancer cells exhibiting protein expression. Weak expression of TM was demonstrated in two thirds of the cases examined, while a strong TM staining was revealed in one third of colon cancers.

Conclusion

Heterogeneous expression of the PC system components in CRC tissue may point to their biological activity modulating tumor growth.     

Circulating microparticles and risk of venous thromboembolism

Introduction

Circulating microparticles (MPs) may trigger a hypercoagulable state, leading to thrombotic complications. Data on their association with venous thromboembolism (VTE) are few and inconsistent.

Materials and methods

To investigate whether or not high levels of MPs are associated with an increased risk of VTE, we carried out a case-control study on 186 patients with a first, objectively diagnosed, episode of VTE and 418 healthy controls. Plasma levels of circulating MPs were measured by flow cytometry.

Results

Patients had higher median plasma levels of total MPs than controls (2184 per μL vs 1769 per μL, p < 0.0001). The risk of VTE increased progressively with increasing MPs, with a linear dose-response effect in the log odds. Individuals with MPs above the 90th percentile of the controls’ distribution (P₉₀ = 3263 per μL) had a 5-fold increased risk of VTE than those with MPs below the 10th percentile of controls (P₁₀ = 913 per μL), independently of sex, age, body mass index, thrombophilia, and plasma factor VIII levels [adjusted odds ratio: 5.30 (95%CI: 2.05-13.7)]. Using the 95th percentile of controls as cut-off (P₉₅ = 4120 per μL), the adjusted odds ratio was 2.20 (1.01-4.79) for individuals with MPs > P₉₅ compared with those having MPs ≤ P₉₅. After exclusion of individuals with antiphospholipid antibodies and hyperhomocysteinemia, the interaction between MPs > P₉₅ and thrombophilia increased the VTE risk from 1.63 (0.60-4.50) to 6.09 (1.03-36.1).

Conclusions

High levels of circulating MPs are a possible independent risk factor for VTE.     

Characterization of a panel of monoclonal antibodies toward mouse PAI-1 that exert a significant profibrinolytic effect in vivo

Introduction

PAI-1 is the main physiological inhibitor of t-PA and u-PA. Elevated PAI-1 levels have been implicated in the pathogenesis of several thrombotic and non-thrombotic diseases. The effect of PAI-1 inhibition can be studied in mouse models, when appropriate immunological tools are available. The majority of the available monoclonal antibodies against PAI-1 have been raised against human PAI-1. Even though some of these antibodies cross-react with non-glycosylated PAI-1 from different species, these antibodies often do not cross-react sufficiently with glycosylated mouse PAI-1. Moreover, the antibodies that cross-react with glycosylated mouse PAI-1 often have decreased inhibitory properties in the presence of vitronectin. Our objective was the generation of a panel of monoclonal antibodies reacting with vitronectin-bound glycosylated mouse PAI-1.

Results

Five monoclonal antibodies revealed binding to glycosylated mouse PAI-1 and exerted a strong (i.e. 58-80% inhibition of PAI-1 activity) inhibitory effect toward mouse PAI-1. Similar inhibitory effects were seen in the presence of a 33-fold molar excess of vitronectin. The PAI-1 inhibitory potential of the antibodies in vivo was demonstrated in a thromboembolism model, in which the evaluated antibodies significantly increased the percentage of mice with normal physical activity in comparison to mice treated with negative control antibody.

Conclusions

To the best of our knowledge this is the first panel of monoclonal antibodies that can inhibit mouse PAI-1 in the presence of vitronectin and that show a profibrinolytic effect in vivo. Therefore these antibodies provide excellent immunological tools to further investigate the role of PAI-1 in mouse models.     

Activated inflammatory cells participate in thrombus size through tissue factor and plasminogen activator inhibitor-1 in acute coronary syndrome: Immunohistochemical analysis

Introduction

Recent studies have suggested that circulating inflammatory cells augment the growth of thrombus in acute coronary syndrome (ACS). We therefore immunohistochemically analyzed thrombi in aspirates obtained from patients immediately after the onset of ACS.

Materials and Methods

Two hundred twenty samples were studied. Total thrombus area, white thrombus area, and red thrombus area were measured. As antibodies in immunohistochemical staining, myeloperoxidase (MPO), CD66b, CD68, p-selectin, tissue factor (TF) and PAI-1were employed respectively.

Results

The ratios of areas of red and white thrombi correlated with whole sample areas of enlarged thrombi (r = 0.48, p < 0.001). The immunohistochemical findings revealed granulocytes and macrophages aggregated around p-selectin-positive platelets that shared the boundary between white and red thrombi, a region where MPO and CD66b expression was abundant in neutrophils. The ratios (%) of MPO- and CD66b-positive cells significantly correlated with whole sample areas (r = 0.50; p < 0.001 and r = 0.49; p < 0.001, respectively). Neutrophils and macrophages within thrombi were positive for TF and PAI-1. Along the boundary between red and white thrombi, TF and PAI-1 positivity coincided with MPO-, CD66b- and CD68-positive cells. The ratios of cells positive for both TF and PAI-1 in this area significantly correlated with the whole sample area (r = 0.43, p < 0.001 and r = 0.60, p < 0.001, respectively).

Conclusions

These results suggested that enhanced activation of peripheral neutrophils together with increased TF and PAI-1 expression might comprise a considerable portion of thrombus enlargement.