Cell Analysis from Dried Blood Spots: New Opportunities in Immunology, Hematology, and Infectious Diseases

Blood cell analysis is a major pillar of biomedical research and healthcare. These analyses are performed in central laboratories. Rapid shipment from collection site to the central laboratories is currently needed because cells and biomarkers degrade rapidly. The dried blood spot from a fingerstick allows the preservation of cellular molecules for months but entire cells are never recovered. Here leucocyte elution is optimized from dried blood spots. Flow cytometry and mRNA expression profiling are used to analyze the recovered cells. 50-70% of the leucocytes that are dried on a polyester solid support via elution after shaking the support with buffer are recovered. While red blood cells lyse upon drying, it is found that the majority of leucocytes are preserved. Leucocytes have an altered structure that is improved by adding fixative in the elution buffer. Leucocytes are permeabilized, allowing an easy staining of all cellular compartments. Common immunophenotyping and mRNAs are preserved. The ability of a new biomarker (CD169) to discriminate between patients with and without Severe Acute Respiratory Syndrome induced by Coronavirus 2 (SARS-CoV-2) infections is also preserved. Leucocytes from blood can be dried, shipped, and/or stored for at least 1 month, then recovered for a wide variety of analyses, potentially facilitating biomedical applications worldwide.

Ultrasound arterial anomalies in patients exposed to nilotinib therapy for chronic myeloid leukemia

INTRODUCTION

Patients exposed to nilotinib for chronic myeloid leukemia (CML) appear to be at risk of arterial complication. The prevalence and aspect of ultrasound asymptomatic arterial lesions are unknown.

OBJECTIVE

To describe prevalence and characteristics of ultrasound arterial anomalies in patients treated with nilotinib for CML.

METHODS

Patients treated with nilotinib from 2006 to 2015 in the department of the Paoli-Calmettes Institute, Marseille, were included retrospectively. A vascular ultrasound screening was carried out from 2010. The arterial lesions at the first examination were described: plaque and its echogenicity, stenosis or occlusion. A vascular arterial anomaly (VAA) was defined by the presence of a clinical and/or ultrasound anomaly. Patients with or without VAA at initial vascular examination were compared using bivariate and multivariate analysis.

RESULTS

74 patients were included (51.4% men, mean age 54.5 years); 25 patients had ultrasound arterial anomalies (33.8%). Carotid bulb was the most involved territory (44%). Arterial anomalies were: 88% plaques, 44%>50% stenosis and 12% occlusion. 72.7% plaques were echolucent or hypoechogenic. A VAA was present in 25 patients with initial vascular evaluation (33.8%). Patients with VAA at baseline were significantly older (64.9 vs 49.3, P<0.001), older at nilotinib initiation (60.8 vs 46.5, P<0.001), with more arterial hypertension (40% vs 12.2%, P=0.01), with more cardiovascular risk factors (P=0.03). In patient with no cardiovascular risk factor 12.5% had VAA (n=24).

CONCLUSION

Nilotinib seems to be associated to arterial lesions of unstable lipid-like appearance. The most involved arterial territory was the carotid bulb and the most common lesion was echolucent or hypoechogenic plaque. VAA can occur in patients without cardiovascular risk factors. This result encourages us to systematically screen and follow all patients exposed to nilotinib even those without cardiovascular risk factors.

Descriptive study of the general practitioners' perception of direct oral anticoagulants and the risk of genital bleeding in women of childbearing age

AIM OF THE STUDY AND PATIENTS

Direct oral anticoagulants (DOA) tend to replace antivitamins K (VKA). The incidence of major and minor hemorrhages is higher in women, a difference potentially linked to genital hemorrhages. The objective is to assess the practices and perception of general practitioners of the use of oral anticoagulant therapy in women of childbearing age.

MATERIALS AND METHODS

Descriptive, observational, transversal and monocentric study. An 11-items questionnaire was sent to 900 randomized general practitioners, assessing the type of patient, the type of anticoagulant prescribed, the management of genital bleeding, and the assessment of the quality of life of anticoagulated patients.

RESULTS

DOA were the most prescribed anticoagulants. Genital hemorrhage was the second leading cause of minor hemorrhage. Most doctors (60.6%) believed they were due to VKAs. 25% reported an alteration in the quality of life of patients following these genital hemorrhages and 47.5% addressed this subject in consultation.

CONCLUSION

Our study suggests that, according to the general practitioners interviewed, genital hemorrhage is more frequent on VKA than on DOA in women of reproductive age, which is contradictory with the data in the literature. The probably taboo subject is rarely mentioned in consultation and is responsible for a deterioration in the quality of life in these young patients. No recommendation exists on the management of this type of genital hemorrhage in these women. An algorithm is proposed for their management.

[Bilateral adrenal hemorrhage under apixaban in primary antiphospholipid syndrome]

INTRODUCTION

Adrenal hemorrhage is a classical but rare complication of antiphospholipid syndrome, revealing diagnosis in one third of the cases. Anti-vitamin K therapy is the standard treatment but direct oral anticoagulants are discussed as an alternative. In the latest recommendations, it is advised not to use direct oral anticoagulants in the setting of antiphospholipid syndrome.

CASE REPORT

We present a case of bilateral adrenal hemorrhage revealing primary antiphospholipid syndrome with triple positive antibody profile, in a 47-year-old man treated by apixaban for previous venous thromboembolism.

CONCLUSION

To our knowledge, it is the first case of adrenal hemorrhage occurring during apixaban treatment in a patient with antiphospholipid syndrome. This case illustrates the inefficacy of direct oral anticoagulants to prevent thrombotic events in antiphospholipid syndrome, in accordance with the latest recommendations.

[Evaluation of an "Emergency Thrombosis" care system in a university-hospital department of general emergencies]

GOAL

Describe the use of diagnostic, prognostic and therapeutic algorithms for venous thromboembolism (VTE), derived from the 2014 European guidelines, in a teaching hospital's emergencies department and compare two groups: the 2015 group "without a care path" and the 2017 group "with a care path".

METHOD

Comparative and retrospective study of the characteristics of emergencies department patients admitted for VTE from January to June 2015 for the 2015 group and from January to June 2017 for the 2017 group.

RESULTS

Seventy-nine patients were included in the 2015 group and 62 patients in the 2017 group. In 24% of cases a clinical probability rule was calculated in the 2017 group (vs. no score in 2015, P<0.05). In the 2015 group, 10% of patients did not have a D-Dimer measurement in case of low clinical probability (vs. 0% in 2017, P<0.05). For both groups, the severity score sPESI was not noted in the medical record. All patients with pulmonary embolism were hospitalized in both groups. A total of 36% of patients with deep vein thrombosis (DVT) were hospitalized in the 2015 group (vs. none in 2017, P<0.05). A total of 52.5% of patients were treated with direct oral anticoagulants (DOAS) in the 2017 group vs. 32.5% in the 2015 group (P<0.05). In 18% of cases DOAS were prescribed by emergency physicians in the 2017 group vs. 2.5% in the 2015 group (P<0.05). Mean hospital stay was 7.4 days in the 2017 group and 9.4 days in the 2015 group (P<0.05).

CONCLUSION

We observed a change in clinical practices and prescriptions after the establishment of an "Emergency Thrombosis" care system. Indeed, improvement in the calculation of the clinical probability score, increase in the outpatient management of DVT, increase in prescribing DOAS and reducing the length of hospital stay were the main revisions. The implementation of standardized digitally calculated clinical and prognostic probability scores would optimize this care path, as well as allow a better distribution of the post-emergency consultations created for outpatients.

Adipose Tissue Expression of Gelatinases in Mouse Models of Obesity

Following the observation by Brown et al. (Am J Physiol 1997; 272: C937-49) that primary rat adipocytes in culture secrete gelatinase A (MMP-2), we have evaluated gelatinase expression in adipose tissue with the use of mouse models of obesity. Wild-type mice were kept on a standard fat diet (SFD) or on a high fat diet (42% fat, HFD) and genetically obese db/db mice were kept on SFD; gonadal and subcutaneous fat pads were removed and analysed ex vivo. These studies revealed that: 1) the HFD induced adipocyte hypertrophy; 2) after 32 weeks, significantly higher levels of 70 kDa (p <0.05) and 65 kDa proMMP-2 (p < 0.01) were observed in extracts of gonadal fat pads of mice on HFD; 3) the contribution of active MMP-2 to the total level was comparable in SFD and HFD groups (20 to 30%); and 4) gelatinase B (MMP-9) was not consistently detected. These findings were confirmed by gelatin zymography and by mRNA determination using competitive RT-PCR. The presence of MMP-2 in the adipose tissue was confirmed immunologically and its localization in adipocytes revealed by immunogold electron microscopy. The potential functional role of MMP-2 in adipose tissue remains to be determined.

Safety and effectiveness of the association ezetimibe-statin (E-S) versus high dose rosuvastatin after acute coronary syndrome: the SAFE-ES study

BACKGROUND

Statin therapy is a cornerstone therapy for secondary prevention after acute coronary syndrome (ACS). However, the use of these drugs can be limited by side effects, mainly muscular pain. Ezetimibe is a newer lipid-lowering agent, with fewer side effects.

AIMS

The present study was designed to compare a commercially available association of ezetimibe and simvastatin (E-S) to high dose Rosuvastatin on cholesterol and muscular enzyme levels and occurrence of muscular pain.

METHODS

All consecutive ACS statin-naïve patients with LDL cholesterol (LDL-C)>100mg/dL randomly received either high dose statin (Rosuvastatin 20mg) or E-S 10/40-mg. All patients had one-month follow-up with biological testing and clinical examination. We compared the two groups on the biological efficiency and incidence of muscular pain.

RESULTS

One hundred and twenty-eight patients were randomized; 64 received E-S and 64 Rosuvastatin. In the two groups, the lowering of LDL-C level (Δ=51%) at one month was significant (P<0.01) without any difference in the rate of lowering on LDL-C or HDL-C suggesting that E-S is as effective as high dose Rosuvastatin (P=0.77 and P=0.99). The rate of patients reaching the objective of LDL-C<100mg/dL (45%) and LDL-C<70mg/dL (51%) was not different in the two clusters (P=0.65). Incidence of muscular pain was 15% higher in patients treated with Rosuvastatin (P=0.01) without any difference on CPK level (P=0.6).

CONCLUSION

Using an association of E-S in an effective alternative strategy to high dose Rosuvastatin with a lower incidence of muscular pain, which might impact adherence to medication after ACS.

[DVT and combined oral contraceptives: update of the pluridisciplinary CNGOF-FNCGM-GEHT-SFMV group]

Thrombotic risk among combined oral contraceptives (COC) users has recently been debated following a court action initiated by a patient. Recent epidemiological data, as well as accumulating biological data underlying these data, have led French Health authorities to modify COC prescription and reimbursement modalities. A short synthesis is proposed by a multidisciplinary group of experts from four French societies (CGOF, FNCGM, GHT, and SFMV).

Systemic chemokine levels, coronary heart disease, and ischemic stroke events: the PRIME study

OBJECTIVES

To quantify the association between systemic levels of the chemokine regulated on activation normal T-cell expressed and secreted (RANTES/CCL5), interferon-γ-inducible protein-10 (IP-10/CXCL10), monocyte chemoattractant protein-1 (MCP-1/CCL2), and eotaxin-1 (CCL11) with future coronary heart disease (CHD) and ischemic stroke events and to assess their usefulness for CHD and ischemic stroke risk prediction in the PRIME Study.

METHODS

After 10 years of follow-up of 9,771 men, 2 nested case-control studies were built including 621 first CHD events and 1,242 matched controls and 95 first ischemic stroke events and 190 matched controls. Standardized hazard ratios (HRs) for each log-transformed chemokine were estimated by conditional logistic regression.

RESULTS

None of the 4 chemokines were independent predictors of CHD, either with respect to stable angina or to acute coronary syndrome. Conversely, RANTES (HR = 1.70; 95% confidence interval [CI] 1.05-2.74), IP-10 (HR = 1.53; 95% CI 1.06-2.20), and eotaxin-1 (HR = 1.59; 95% CI 1.02-2.46), but not MCP-1 (HR = 0.99; 95% CI 0.68-1.46), were associated with ischemic stroke independently of traditional cardiovascular risk factors, hs-CRP, and fibrinogen. When the first 3 chemokines were included in the same multivariate model, RANTES and IP-10 remained predictive of ischemic stroke. Their addition to a traditional risk factor model predicting ischemic stroke substantially improved the C-statistic from 0.6756 to 0.7425 (p = 0.004).

CONCLUSIONS

In asymptomatic men, higher systemic levels of RANTES and IP-10 are independent predictors of ischemic stroke but not of CHD events. RANTES and IP-10 may improve the accuracy of ischemic stroke risk prediction over traditional risk factors.

Effects of insulin-like growth factor 1 in preventing acute coronary syndromes: the PRIME study

OBJECTIVE

Insulin-like growth factor-1 (IGF-1) has been associated with cardiovascular risk factors and atherosclerosis. The aim of the present study was to evaluate the prognostic value of IGF-1 concentrations with respect to occurrence of well-defined coronary syndromes.

METHODS

The PRIME study is a prospective cohort having included 10,600 subjects from Northern Ireland and France. Detailed information on cardiovascular risk factors, socioeconomic and behavioural variables were collected and a cardiologic examination was performed. At 5-year follow-up, 317 incident cases of coronary events were recorded according to strict protocols. They were matched to 634 age- and centre-paired controls from the same cohort, free of coronary disease. Baseline IGF-1 concentrations were measured, together with variables of lipid and glucose metabolism and markers of vascular and systemic inflammation.

RESULTS

Baseline IGF-1 concentration was lower in subjects developing an acute coronary syndrome than in unaffected controls. IGF-1 levels correlated negatively with age, waist circumference, tobacco consumption and markers of inflammation. Subjects in the highest quartile of IGF-1 distribution had a 55% reduction in the relative risk of developing myocardial infarction and a 45% decrease for all-combined acute coronary syndromes. A similar trend, although non-significant, was noted for angina pectoris. Multiple adjustments on classical risk factors and inflammation markers did not affect IGF-1 results. Elevated levels of both IGF-1 and apo A-I conferred a significantly greater risk reduction than either one alone. However, interaction between the two markers was not significant.

CONCLUSION

Like HDL markers, high levels of IGF-1 confer protection against coronary artery disease.

Combined segregation-linkage analysis of plasma thrombin activatable fibrinolysis inhibitor (TAFI) antigen levels with TAFI gene polymorphisms

By decreasing plasminogen binding to fibrin surface, the thrombin activatable fibrinolysis inhibitor (TAFI) has been hypothesized to constitute an early marker for atherothrombotic diseases. Previous studies have shown that plasma TAFI levels exhibit a high interindividual variability that is only poorly explained by lifestyle factors. Several polymorphisms of the TAFI gene have been described, and a combination of a C+1542G substitution in the 3' untranslated region and an Ala147Thr amino acid change has been shown to explain 60% of TAFI variability in a sample of unrelated individuals. A segregation-linkage analysis was performed to determine whether these polymorphisms are directly involved in the genetic regulation of TAFI levels, or whether they are only markers in linkage disequilibrium (LD) with unmeasured TAFI-linked quantitative trait loci (QTLs). The sample consisted of 97 healthy nuclear families from the Stanislas Cohort. The C+1542G and Ala147Thr polymorphisms were in complete negative LD, with minor allele frequencies of 0.27 and 0.28, respectively. Results of the segregation-linkage analysis provided evidence of two TAFI-linked QTLs in LD with the two measured polymorphisms, which would explain 78% of the TAFI variance, as compared with 55% explained by the C+1542G and the Ala147Thr polymorphisms combined. The two putative QTLs would have minor allele frequencies of 0.45 and 0.32, respectively. The hypothesis that one of the measured polymorphisms is one of the QTLs was rejected. The putative QTLs also did not seem compatible with the other TAFI gene polymorphisms that we have previously described. More extensive sequencing of the TAFI gene is necessary to identify the functional variants.

Adipose tissue expression of gelatinases in mouse models of obesity

Following the observation by Brown et al. (Am J Physiol 1997; 272: C937-49) that primary rat adipocytes in culture secrete gelatinase A (MMP-2), we have evaluated gelatinase expression in adipose tissue with the use of mouse models of obesity. Wild-type mice were kept on a standard fat diet (SFD) or on a high fat diet (42% fat, HFD) and- genetically obese db/db mice were kept on SFD; gonadal and subcutaneous fat pads were removed and analysed ex vivo. These studies revealed that: 1) the HFD induced adipocyte hypertrophy; 2) after 32 weeks, significantly higher levels of 70 kDa (p <0.05) and 65 kDa proMMP-2 (p <0.01) were observed in extracts of gonadal fat pads of mice on HFD; 3) the contribution of active MMP-2 to the total level was comparable in SFD and HFD groups (20 to 30%); and 4) gelatinase B (MMP-9) was not consistently detected. These findings were confirmed by gelatin zymography and by mRNA determination using competitive RT-PCR. The presence of MMP-2 in the adipose tissue was confirmed immunologically and its localization in adipocytes revealed by immunogold electron microscopy. The potential functional role of MMP-2 in adipose tissue remains to be determined.

Fat cell function and fibrinolysis

Plasminogen activator inhibitor-1 (PAI-1) is a specific inhibitor of plasminogen activators and may be the principal regulator of plasminogen activation in vivo. PAI-1 levels are elevated in insulin-resistant subjects and are associated with an increased risk of atherothrombosis. After adjustment for metabolic parameters, increased PAI-1 levels were no longer considered as a cardiovascular risk factor. The mechanisms underlying the strong association between PAI-1 levels and the metabolic disturbances found in insulin resistance are still not understood. Several studies have suggested that visceral adipose tissue may be a major source of PAl-1. Accordingly, adipose tissue PAI-1 production particularly that from visceral fat, was found to be elevated in obese human subjects. Within human adipose tissue, stromal cells appear to be the main cells involved in PAI-1 synthesis. This review discusses the potential mechanisms linking adipose tissue to plasma PAI-1 levels such as the intervention of cytokines (TNFalpha and TGFbeta), free fatty acids and hormones (insulin and glucocorticoids). Moreover alteration of adipose tissue cellular composition induced by the modulation of PAI-1 expression opens a novel field of interest.

Plasminogen activator inhibitor 1, transforming growth factor-beta1, and BMI are closely associated in human adipose tissue during morbid obesity

In adipose tissue from both obese mice and humans, plasminogen activator inhibitor 1 (PAI-1) expression has been reported to be upregulated to levels of increased plasma PAI-1. This elevated expression has been shown to be partly controlled by tumor necrosis factor (TNF)-alpha in mice. In humans, increased PAI-1 expression is associated with insulin resistance characterized by visceral fat accumulation. Therefore, the aim of this study was to investigate the expression pattern of PAI-1 and TNF-alpha (antigen and mRNA) in visceral human adipose fat in comparison with subcutaneous (SC) fat. Because transforming growth factor (TGF)-beta1 is a potent inducer of PAI-1 synthesis and has been shown to influence adipocyte metabolism, this work was extended to TGF-beta1 quantification. A total of 32 obese individuals (BMI 42 +/- 6.8 kg/m2) were investigated. Freshly collected visceral adipose tissue did not exhibit a higher content of PAI-1 or TGF-beta1 than did SC tissue. Although most of the TNF-alpha values were at the detection limit of the methods, TNF-alpha antigen was 3-fold higher and TNF-alpha mRNA was 1.2-fold higher in visceral fat. The levels of tissue TGF-beta1 antigen correlated well with those of PAI-1 antigen, regardless of the fat depot studied (SC tissue: n = 21, r = 0.72, P = 0.0006; visceral tissue: n = 20, r = 0.49, P < 0.03), and they were both significantly associated with BMI. Conversely, no relationship was observed between the levels of TNF-alpha and PAI-1 or TNF-alpha and BMI. Tissue PAI-1 levels were also significantly correlated with those of circulating PAI-1. These results describe, in severe obesity, a proportional increase in tissue PAI-1 and TGF-beta1 in visceral and SC tissues. This increased PAI-1 expression could be the result of tissue cytokine disturbances, such as elevated TGF-beta1 expression.

Catastrophic arterial reactivity during primary antiphospholipid syndrome--a case report

Arterial reactivity leading to acute thrombosis at the site of a needle stick injury has never been described during antiphospholipid syndrome. The authors report a case characterized by a succession of thrombotic events occurring during or immediately after arterial angiographies or arterial surgery, in which catastrophic arterial reactivity can be strongly suspected. In this particular patient, it can be postulated that damage to the endothelial cells of the vessels injured during manipulation may have precipitated or aggravated the preexisting susceptibility to thrombosis.

Fibrinolytic function and coronary risk

Plasminogen activation potential in the blood is controlled by an equilibrium between plasminogen activators, mainly tissue-type plasminogen activator (t-PA), and inhibitors, mainly plasminogen activator inhibitor (PAI)-1. In cardiovascular practice, imbalance of this fibrinolytic potential is encountered primarily in the insulin-resistance syndrome. This syndrome leads to increased plasma PAI-1 and t-PA antigen levels (reflecting inactive t-PA/PAI-1 complexes) with a consequent decrease in fibrinolytic activity. Increased plasma PAI-1 and t-PA antigen both are predictive of myocardial infarction. The prognostic value of PAI-1 disappears after adjustments for insulin resistance markers, whereas the prognostic value of t-PA antigen disappears after simultaneous adjustments for insulin resistance and inflammation markers, suggesting an additive role of inflammation in inducing plasma fibrinolytic markers. Recently the production of PAI-1 by adipose tissue, in particular by tissue from the omentum, has been shown. PAI-1 produced in this way could be an important contributor to the elevated plasma PAI-1 levels observed in insulin-resistant patients. These results support the notion that PAI-1 may be a link between obesity, insulin resistance, and cardiovascular disease. Genetic control of PAI-1 expression has also been shown, involving a -675 4G/5G polymorphism, the 4G/4G genotype being associated with higher plasma PAI-1 levels; its proper influence on the development of myocardial infarction is still debated.

Relationship of plasminogen activator inhibitor-1 levels following thrombolytic therapy with rt-PA as compared to streptokinase and patency of infarct related coronary artery

BACKGROUND

Type 1 plasminogen activator inhibitor (PAI-1) is considered to be risk factor for acute myocardial infarction (AMI). A rebound of circulating PAI-1 has been reported after rt-PA administration. We investigated the relationships between PAI-1 levels before and after thrombolytic therapy with streptokinase (SK) as compared to rt-PA and the patency of infarct-related arteries.

METHODS AND RESULTS

Fifty five consecutive patients with acute MI were randomized to streptokinase or rt-PA. The plasma PAI-1 levels were studied before and serially within 24 h after thrombolytic administration. Vessel patency was assessed by an angiogram at 5+/-1days. The PAI-1 levels increased significantly with both rt-PA and SK as shown by the levels obtained from a control group of 10 patients treated with coronary angioplasty alone. However, the area under the PAI-1 curve was significantly higher with SK than with rt-PA (p<0.01) and the plasma PAI-1 levels peaked later with SK than with rt-PA (18 h versus 3 h respectively). Conversely to PAI-1 levels on admission, the PAI-1 levels after thrombolysis were related to vessel patency. Plasma PAI-1 levels 6 and 18 h after SK therapy and the area under the PAI-1 curve were significantly higher in patients with occluded arteries (p<0.002, p<0.04 and p<0.05 respectively). The same tendency was observed in the t-PA group without reaching significance.

CONCLUSIONS

This study showed that the PAI-1 level increase is more pronounced after SK treatment than after t-PA treatment. There is a relationship between increased PAI-1 levels after thrombolytic therapy and poor patency. Therapeutic approaches aimed at quenching PAI-1 activity after thrombolysis might be of interest to improve the efficacy of thrombolytic therapy for acute myocardial infarction.

Activation of plasminogen activator inhibitor-1 synthesis by phorbol esters in human promyelocyte HL-60--roles of PCKbeta and MAPK p42

HL-60 cells treated by PMA develop the monocyte adherent phenotype and synthesize plasminogen activator inhibitor type-1 (PAI-1). We focused our study on the identification of the PMA-activated protein kinase C (PKC) isoform and its downstream transduction pathway activating PAI-1 synthesis. Acquisition of the monocytic phenotype was evidenced by cell adherence (90-95%) and a sharp increase of CD 36 and receptor for urokinase plasminogen activator (uPAR) surface expression. Ro 31-8220, a specific inhibitor of PKC, prevented PMA-induced PAI-1 synthesis (mRNA and protein levels) and cell adhesion. To identify the PKC isoform, we took advantage of the HL-525 cell line, an HL-60 cell variant deficient in PKCbeta gene expression. This defect prevents PMA to induce the differentiation process. HL-525 stimulated by PMA did not synthesize PAI-1 nor become adherent. However, in HL-525 cells either pretreated by retinoic acid that reinduces PKCbeta gene expression or transfected with PKCbeta cDNA, PMA significantly activated PAI-1 synthesis and adhesion of cells. Immunoblotting of active Mitogen Activated Protein Kinase (MAPK) p42/p44 in HL-60 cells showed a preferential and sustained activation of the p42 isoform by PMA over the p44 isoform. Ro 31-8220 significantly attenuated this activation. PD 098059 and U0126, both highly specific MEK inhibitors, efficiently prevented PMA-induced PAI-1 synthesis (mRNA and protein levels) and cell adhesion whereas SB203580, a specific inhibitor of stress-activated MAPK p38, did not. Results obtained from HL-60 and HL-525 cells indicate that the PMA-activated transduction pathway of uPAR expression involves a PKC isoform other than PKCbeta. In conclusion, we propose that the pathway PKCbeta-MEK-MAPK p42 is a potential linear route for PAI-1 synthesis leading to morphological changes and adherence linked to PMA-induced differentiation in HL-60 cells.

Effect of weight change and metformin on fibrinolysis and the von Willebrand factor in obese nondiabetic subjects: the BIGPRO1 Study. Biguanides and the Prevention of the Risk of Obesity

OBJECTIVE

Insulin resistance is associated with hypofibrinolysis. Metformin has been shown to improve insulin sensitivity and fibrinolysis. Its action on fibrinolysis and the von Willebrand factor was evaluated in the Biguanides and the Prevention of the Risk of Obesity (BIGPRO)1 trial in nondiabetic men (n = 151) and women (n = 306) aged between 34 and 65 years with a central fat distribution and a mean BMI of 32.5 kg/m2.

RESEARCH DESIGN AND METHODS

The subjects were randomly allocated to a 1-year treatment with metformin (850 mg b.i.d.) or placebo, in addition to diet and exercise recommendations.

RESULTS

Plasminogen activator inhibitor 1 (PAI-1) activity and antigen decreased significantly but similarly by 30 and 40%, respectively, in both the placebo and the metformin groups. This decrease occurred mainly in subjects who lost weight. Metformin did not have any significant additional effect on PAI-1. In contrast to the results for PAI-1, there was a significantly greater decrease in tissue-type plasminogen activator (tPA) antigen in the metformin than in the placebo group (mean+/-SD: -1.1+/-3.1 vs. 0.2+/-3.2 ng/ml, P < 0.02). The von Willebrand factor (vWF) also decreased significantly more in the metformin group (-0.17+/-0.42 vs. -0.05+/-0.38 U/I, P < 0.02).

CONCLUSIONS

Weight loss was the main factor associated with the decrease in PAI-1, in accordance with the recent demonstration of production of PAI-1 by adipocytes. Metformin had a significant effect on two factors, tPA antigen and vWF, mainly secreted by the endothelial cells, which suggests an effect of the drug on the production or the metabolism of these two hemostatic proteins.

Production of plasminogen activator inhibitor 1 by human adipose tissue: possible link between visceral fat accumulation and vascular disease

Plasminogen activator inhibitor type 1 (PAI-1) contributes to the pathogenesis of atherothrombosis. Its plasma level is strongly correlated with parameters that define the insulin resistance syndrome, in particular with BMI and visceral accumulation of body fat, suggesting that PAI-1 may be an adipose tissue-derived circulating peptide. The present study was designed to investigate PAI-1 expression by human adipose tissue and its different cellular fractions. Special interest has been paid to the amount of PAI-1 antigen produced by omental versus subcutaneous fat. PAI-1 protein detected by immunolocalization was present at the stromal and adipocyte levels. PAI-1 mRNA was detected in stromal vascular cells freshly isolated and under culture conditions. It was also detected in whole adipose tissue and adipocyte fraction under culture conditions. The mRNA signal from the adipocyte fraction was detected as early as 2 h of incubation. The increase in PAI-1 mRNA was followed by an increase in PAI-1 antigen in the conditioned medium that was suppressed by treatment with cycloheximide. Transforming growth factor-beta1 significantly increased PAI-1 antigen production by the adipocyte fraction, whereas tumor necrosis factor-alpha did not have any effect. Interestingly, after 5 h of incubation, omental tissue explants produced significantly more PAI-1 antigen than did subcutaneous tissue from the same individual, whereas similar production of leptin by the two territories was observed. These results strongly suggest that human adipose tissue, in particular visceral tissue, can be an important contributor to the elevated plasma PAI-1 levels observed in central obesity.