Interleukin-10 promoter microsatellite polymorphisms influence the immune response to heparin and the risk of heparin-induced thrombocytopenia

INTRODUCTION

Heparin-induced thrombocytopenia (HIT) results from an atypical immune response with synthesis of IgG antibodies (Abs) to platelet factor 4/heparin complexes (PF4/H), and probably involves both B and T cells. We investigated whether 3 single nucleotide polymorphisms (SNPs), rs1800896 (-1082G/A), rs1800871 (-819C/T) and rs1800872 (-592C/A) and the polymorphic CA repeat microsatellites IL10R [5325CA(11_15)] and IL10G [8134CA(14_29)] are associated with the synthesis of Abs to PF4/heparin and HIT.

MATERIALS AND METHODS

Eighty-two patients with definite HIT and two control groups were studied. The first control group (Ab(neg)) consisted of 85 patients without Abs to PF4/heparin after cardiopulmonary bypass (CPB). The second control group (Ab(pos)) consisted of 84 patients who had developed significant levels of PF4-specific antibodies after CPB, but without HIT.

RESULTS

Allele frequencies of the 3 SNPs were similar in HIT patients and controls. Fourteen alleles in IL10G (G16 to G29) and 3 alleles in IL10R (R13 to R15) were defined. The short G20 allele of IL10G was more frequent in Ab(neg) patients (8.2%) than in Ab(pos) (2.9%) and HIT patients (3%). It thereby appeared to protect against developing Abs to PF4/heparin (OR 0.29; 95% CI [0.12-0.70], p=0.006). Combined haplotypes cH1/cH8 comprising the short G20 + R13 alleles were less frequent in HIT (OR 0.33; 95% CI [0.11-0.97], p=0.036), and levels of Abs to PF4 in Ab(pos) patients were lower in cH1/cH8 subjects (p=0.019).

CONCLUSION

These results suggest that IL10 promoter microsatellite polymorphisms might influence the immune response against PF4/heparin and the risk of HIT.

Clinical, angiographic, and genetic factors associated with early coronary stent thrombosis

CONTEXT

Despite dual antiplatelet therapy, stent thrombosis remains a devastating and unpredictable complication of percutaneous coronary intervention (PCI).

OBJECTIVE

To perform a sequential analysis of clinical and genetic factors associated with definite early stent thrombosis.

DESIGN, SETTING, AND PARTICIPANTS

Case-control study conducted in 10 centers in France between January 2007 and May 2010 among 123 patients undergoing PCI who had definite early stent thrombosis and DNA samples available, matched on age and sex with 246 stent thrombosis-free controls.

MAIN OUTCOME MEASURE

Accuracy of early stent thrombosis prediction by 23 genetic variants.

RESULTS

Among the 23 genetic variants investigated in 15 different genes, the significant determinants of early stent thrombosis were CYP2C19 metabolic status (adjusted odds ratio [OR], 1.99; 95% CI, 1.47-2.69), ABCB1 3435 TT genotype (adjusted OR, 2.16; 95% CI, 1.21-3.88), and ITGB3 PLA2 carriage (adjusted OR, 0.52; 95% CI, 0.28-0.95). Nongenetic independent correlates were acuteness of PCI (adjusted OR, 3.05; 95% CI, 1.54-6.07), complex lesions (American College of Cardiology/American Heart Association type C) (adjusted OR, 2.33; 95% CI, 1.40-3.89), left ventricular function less than 40% (adjusted OR, 2.25; 95% CI, 1.09-4.70), diabetes mellitus (adjusted OR, 1.82; 95% CI, 1.02-3.24), use of proton pump inhibitors (adjusted OR, 2.19; 95% CI, 1.29-3.75), and higher clopidogrel loading doses (adjusted OR, 0.73; 95% CI, 0.57-0.93). The discriminative accuracy of the clinical-only model was similar to that of a genetic-only model (area under the curve, 0.73 [95% CI, 0.67-0.78] vs 0.68 [95% CI, 0.62-0.74], respectively; P = .34). A combined clinical and genetic model led to a statistically significant increase in the discriminatory power of the model compared with the clinical-only model (area under the curve, 0.78 [95% CI, 0.73-0.83] vs 0.73 [95% CI, 0.67-0.78]; P = .004).

CONCLUSIONS

This case-control study identified 3 genes (CYP2C19, ABCB1, and ITGB3) and 2 clopidogrel-related factors (loading dose and proton pump inhibitors) that were independently associated with early stent thrombosis. Future studies are needed to validate the prognostic accuracy of these risk factors in prospective cohorts.

[Specificities of neonatal hemostasis and implications in pathologic situations]

The haemostasis of healthy newborn differs from those of normal adult but remains well balanced without bleeding or thrombosis. However, this equilibrium is unstable, and the neonate is exposed to acquired or inherited haemostasis disorders that necessitate to be early diagnosed in order to be appropriately treated. Several studies provided reference ranges for haemostatic components in the foetus, the newborn and throughout childhood. The particularities of neonatal haemostasis are therefore better defined and contribute to further understand the pathophysiology and characteristics of hemorrhagic and thrombotic disorders that occur in newborns. Some examples of the impact of age on haemostasis are: the risk of neonatal alloimmune thrombocytopenia is high in the first newborn of a woman at risk since the involved antigens are fully expressed by foetal platelets; the newborn is at risk for vitamin K deficiency with bleeding due to poor transport of vitamin K across the placenta and low levels of coagulation factors II, VII, IX, X; the diagnosis of some inherited coagulation deficiencies can be difficult in the newborn due to physiologically low levels of coagulation factors; thrombotic events are rare in the healthy neonate, despite physiologically very low levels of several coagulation inhibitors; the pharmacokinetic and effects of antithrombotic agents are influenced by the specificities of haemostasis in neonates. This review will discuss about the foetal development of haemostasis until birth, and some implications regarding the pathophysiology, the diagnosis and the treatment of bleeding disorders in the human neonate.

Comparative study of coagulation and thrombin generation in the portal and jugular plasma of patients with cirrhosis

Portal vein thromboses are frequent in cirrhotic patients and may be favoured by hypercoagulability in the splanchnic venous system. The coagulation balance and thrombin generation (TG) were evaluated in platelet-free plasma obtained from portal and systemic blood samples in 28 cirrhotic patients while undergoing transjugular intrahepatic porto-systemic shunt. TG assay (TGA) was performed with all samples from cirrhotic patients and with plasma samples from 14 healthy controls, with varying concentrations of tissue factor and phospholipids, with or without thrombomodulin. Screening tests and specific assays were also performed and activated partial thromboplastin time was shorter in portal plasma samples with higher FVIII and lower protein C levels, well correlated with Child-Pugh scores, and higher D-dimers and F1+2 levels However, all TGA parameters were similar in portal and jugular samples, possibly due in part to similar concentrations of factor II and antithrombin in these two sites of plasma sampling. TGA showed lower thrombin peaks and endogenous thrombin potential values in cirrhotic plasma compared to those of healthy controls. Importantly, a resistance to thrombomodulin that well correlated with factor VIII and PC levels, was evidenced in all samples from patients with cirrhosis, and was more significant in those from severely affected cases. This study therefore supports the existence of a relative hypercoagulability in the portal vein of cirrhotic patients that is likely due to protein C/S deficiency and to high FVIII levels.

Increased tissue factor expression is associated with reduced survival in non-small cell lung cancer and with mutations of TP53 and PTEN

BACKGROUND

Tissue factor (TF), the main initiator of blood coagulation, is also a signaling protein that regulates cancer progression. TF synthesis was recently shown to be affected by tumor suppressor genes (TSGs) in tumor cell lines. We therefore studied TF gene (F3) expression and the status of genes coding for tumor protein p53 (TP53), phosphatase and tensin homolog (PTEN), and serine/threonine kinase 11 (STK11) in non-small cell lung cancer (NSCLC). Heparanase (HPSE) gene expression was also measured because this endo-beta-D-glucuronidase was recently shown to enhance TF gene expression.

METHODS

TF and heparanase mRNA expression was measured by real-time PCR in 53 NSCLC tumors. Exons 5-8 of TP53 were sequenced from genomic DNA. Mutations of PTEN and STK11 were screened by multiplex ligation-dependent probe amplification.

RESULTS

TF mRNA levels were significantly higher in T(3)-T(4) tumors (P = 0.04) and in stages III-IV of NSCLC (P = 0.03). Mutations of TP53, STK11, and PTEN were identified in 20 (37.7%), 21 (39%), and 20 (37.7%) of tumors, respectively. TF expression was higher in mutated TP53 (TP53(Mut)) (P = 0.02) and PTEN(Mut) (P = 0.03) samples. Moreover, TF mRNA increased from 2700 copies (no mutation) to 11 6415 when 3 TSG were mutated. Heparanase gene expression did not differ according to TF gene (F3) expression or TSG mutation. The median survival time was shorter in patients with tumor TF mRNA levels above median values (relative risk 2.2; P = 0.03, multivariate analysis) and when TP53 was mutated (relative risk 1.8; P = 0.02).

CONCLUSIONS

These results provide clear evidence that combined oncogene events affecting TSG dramatically increase TF gene expression in lung tumors. Moreover, this study suggests that TF gene expression could be used as a prognostic marker in NSCLC.

Risk factors for unfavorable clinical outcome in patients with documented heparin-induced thrombocytopenia

BACKGROUND

Prognostic factors for unfavorable clinical outcome in patients with heparin-induced thrombocytopenia (HIT) are largely unknown.

DESIGN AND METHODS

In this multicenter, retrospective, case-control study, all HIT patients were treated with danaparoid. Study cases were HIT patients with an unfavorable clinical outcome. Controls were HIT patients who were not study cases. Unfavorable clinical outcome was defined as the occurrence of at least one of the following clinical events: death within 60 days after HIT start date, or venous or arterial thromboembolism, amputation, major bleeding, or disseminated intra-vascular coagulation between 48 hours and 60 days after HIT start date.

RESULTS

Compared with controls (n=65), thrombotic episodes within 48 hours of HIT start date were more frequent (59.2% versus 32.3%; p=0.004), the median time between HIT start date and initiation of danaparoid infusion was longer (3.0 versus 1.0 days; p=0.001), and this treatment was more frequently underdosed (43.8% versus 18.8%; p=0.004) in study cases (n=49). Upon multivariate analysis, all these three parameters were significant predictive factors for unfavorable clinical outcome. The adjusted odds ratios [95% confidence interval] were 6.6 [2.5-17.3] for time between HIT start date and danaparoid initiation over 48 hours, 4.3 [1.5-12.0] for danaparoid underdosing, and 3.2 [1.3-8.0] for presence of a thromboembolic episode at HIT start date.

CONCLUSIONS

This study supports the recommendations concerning the management of HIT patients, namely discontinuation of all heparin administration once the diagnosis is suspected and prompt initiation of an alternative anticoagulant drug with a strict adherence to doses specifically recommended for these patients.

[Prolongation of anti vitamin K treatment for 18 months versus placebo after 6 months treatment of a first episode of ideopathic pulmonary embolism: a mutlicentre, randomised double blind trail. The PADIS-EP Trial]

BACKGROUND

After stopping a 3 to 6 months course of oral anticoagulation for a first episode of idiopathic venous thromboembolism (VTE), the risk of recurrent VTE is high (10% per year). In this setting, international guidelines recommend at least 6 months treatment. However, this recommendation is not satisfactory for the following reasons: (1) no randomized trial has compared 6 months to extended duration (2 years) anticoagulation; and (2), even though the frequency of recurrent VTE is similar after pulmonary embolism (PE) and deep vein thrombosis (DVT), the fatality rate of recurrent VTE after PE is higher than that after DVT.

METHODS

A French multicentre double blind randomized trial. The main objective is to demonstrate, after a first episode of symptomatic idiopathic PE treated for 6 months using a vitamin K antagonist, that extended anticoagulation for 18 months (INR between 2 and 3) is associated with an increased benefit / risk ratio (recurrent VTE and severe anticoagulant-related bleeding) compared to placebo. The double blind evaluation is ensured using by active warfarin and placebo, and blinded INR. The protocol was approved by the ethics board of the Brest Hospital on the 7th of March 2006. For an alpha risk of 5% and a beta risk of 20%, the estimated sample size is 374 patients.

EXPECTED RESULTS

This study has the potential to: (1) demonstrate that the benefit / risk ratio of extended anticoagulation for 18 months is higher than that observed with placebo in patients with a first episode of idiopathic PE initially treated for 6 months, during and after the treatment period; and (2) to validate or invalidate the contribution of isotope lung scans, lower limb Doppler ultrasound and D-Dimer at 6 months of treatment as predictors of recurrent VTE (medico-economic analysis included).

Changes in antithrombin and fibrinogen levels during induction chemotherapy with L-asparaginase in adult patients with acute lymphoblastic leukemia or lymphoblastic lymphoma. Use of supportive coagulation therapy and clinical outcome: the CAPELAL study

BACKGROUND

The effects of L-asparaginase on hemostasis during induction chemotherapy are less defined in adults than in children. We, therefore, studied the effects of L-asparaginase in adult patients.

DESIGN AND METHODS

This was a retrospective analysis of 214 patients treated with L-asparaginase (7500 IU/m(2) x 6) for acute lymphoblastic leukemia or lymphoblastic lymphoma. Between day 1 of the induction course and discharge, clinical events, and biological and therapeutic modifications were reviewed.

RESULTS

Antithrombin and fibrinogen levels were lower than 60% and 1 g/L in 71% and 73% of patients, respectively. Twenty thromboses occurred in 9.3% of the patients; these patients had a median antithrombin level of 53% (range, 21-111) at the time of the event. Forty-two episodes of bleeding occurred in 31 patients with a median fibrinogen level of 1.3 g/L. Infusions of L-asparaginase were reduced or delayed in 64% of patients due to low fibrinogen and/or antithrombin levels. Fresh-frozen plasma, antithrombin and fibrinogen were infused in 31%, 41% and 52% of patients, respectively. The mean antithrombin and fibrinogen levels increased from 61% to 88% and from 1 to 1.4 g/L after infusion of antithrombin or fibrinogen respectively, while both levels remained unchanged after the infusion of fresh-frozen plasma. In patients who received antithrombin concentrates L-asparaginase injections were less frequently omitted or delayed (53% vs. 72%, p=0.005), the rate of thrombosis was lower (4.8% vs. 12.2%, p=0.04) and the disease-free survival was also reduced (p=0.05).

CONCLUSIONS

This retrospective study suggests that antithrombin concentrates may have a beneficial effect on the outcome of adults treated for acute lymphoblastic leukemia with L-asparaginase; prospective studies are essential to confirm this hypothesis.

High frequency ultrasound device to investigate the acoustic properties of whole blood during coagulation

This study was designed to investigate the changes in acoustic properties of whole blood during the coagulation process. High frequency (from 20 to 40 MHz) ultrasound parameters were measured both in double transmission (DT) and backscattering (BS) mode to assess sound velocity and backscatter coefficient, respectively. The integrated backscatter coefficient (IBC) and the effective scatterer size (ESS) were deducted from the backscatter coefficient. Measurements were performed on whole blood samples collected from 12 healthy volunteers. During the blood clotting process (2 h observation), acoustic parameters were measured with 15 s time resolution for the transmission parameter and 5 s (for the 5 first min) and 30 s (for the end of the observation time) for the backscattering parameters. The results obtained clearly showed that simultaneous measurements of parameters in DT and BS modes are able to identify several stages during the in vitro blood clotting process. In particular, red blood cell (RBC) aggregation can be described from the backscattering parameters and liquid-gel transition phase of blood from the sound velocity. Intra- and inter-individual dispersion of these parameters were also measured and discussed.

Treatment of inherited protein C deficiency by replacement therapy with the French purified plasma-derived protein C concentrate (PROTEXEL®)

BACKGROUND/OBJECTIVES

A multicentre retrospective study was performed to assess the efficacy/safety of a French purified plasma-derived protein C (PC) concentrate in inherited PC deficiency.

MATERIALS AND METHODS

Nine patients were enrolled, five children aged < 5 weeks, among whom four with a severe deficiency were homozygous, and four patients < 37 years with PC levels ranging 14-25%, including one compound heterozygous.

RESULTS

Thirty replacement therapy courses were recorded with mean PC dosages ranging between 24-90 IU/kg/day for prophylactic courses and 51-209 IU/kg/day for treatment courses. Recoveries varied between 0.8 and 1.12% IU/kg in preventive situations and between 1.09 and 1.91% IU/kg for treatment courses; 23 treatment courses were performed in patients aged 1 day to 18 years, 19 out of 23 treatments resulted in complete recovery with no sequelae. Treatment efficacy was difficult to assess in four out of 23 cases because the thrombotic event was not confirmed in one case and due to late treatment initiation in the three other cases. Seven prophylactic treatments were used either in association of vitamin K antagonists or to prevent thrombotic events due to vitamin K antagonist introduction or withdrawal. The safety assessed during 914 infusions was excellent. No abnormal bleeding was reported, including with high doses, during surgery, with heparin therapy.

CONCLUSIONS

Replacement therapy with this French PC concentrate is safe and effective in patients with inherited PC deficiency.