Relationship between soluble thrombomodulin in plasma and coagulation or fibrinolysis in type 2 diabetes

Endothelial biomarkers (Von willebrand factor, BDCA3, urokinase) as predictors of mortality in COVID-19 patients: cohort study

BACKGROUND

SARS-CoV-2 is a systemic disease that affects endothelial function and leads to coagulation disorders, increasing the risk of mortality. Blood levels of endothelial biomarkers such as Von Willebrand Factor (VWF), Thrombomodulin or Blood Dendritic Cell Antigen-3 (BDCA3), and uUokinase (uPA) increase in patients with severe disease and can be prognostic indicators for mortality. Therefore, the aim of this study was to determine the effect of VWF, BDCA3, and uPA levels on mortality.

METHODS

From May 2020 to January 2021, we studied a prospective cohort of hospitalized adult patients with polymerase chain reaction (PCR)-confirmed COVID-19 with a SaO2 ≤ 93% and a PaO2/FiO2 ratio < 300. In-hospital survival was evaluated from admission to death or to a maximum of 60 days of follow-up with Kaplan-Meier survival curves and Cox proportional hazard models as independent predictor measures of endothelial dysfunction.

RESULTS

We recruited a total of 165 subjects (73% men) with a median age of 57.3 ± 12.9 years. The most common comorbidities were obesity (39.7%), hypertension (35.4%) and diabetes (30.3%). Endothelial biomarkers were increased in non-survivors compared to survivors. According to the multivariate Cox proportional hazard model, those with an elevated VWF concentration ≥ 4870 pg/ml had a hazard ratio (HR) of 4.06 (95% CI: 1.32-12.5) compared to those with a lower VWF concentration adjusted for age, cerebrovascular events, enoxaparin dose, lactate dehydrogenase (LDH) level, and bilirubin level. uPA and BDCA3 also increased mortality in patients with levels ≥ 460 pg/ml and ≥ 3600 pg/ml, respectively.

CONCLUSION

The risk of mortality in those with elevated levels of endothelial biomarkers was observable in this study.

Sex and aging signatures of proteomics in human cerebrospinal fluid identify distinct clusters linked to neurodegeneration

Sex and age are major risk factors for chronic diseases. Recent studies examining age-related molecular changes in plasma provided insights into age-related disease biology. Cerebrospinal fluid (CSF) proteomics can provide additional insights into brain aging and neurodegeneration. By comprehensively examining 7,006 aptamers targeting 6,139 proteins in CSF obtained from 660 healthy individuals aged from 43 to 91 years old, we subsequently identified significant sex and aging effects on 5,097 aptamers in CSF. Many of these effects on CSF proteins had different magnitude or even opposite direction as those on plasma proteins, indicating distinctive CSF-specific signatures. Network analysis of these CSF proteins revealed not only modules associated with healthy aging but also modules showing sex differences. Through subsequent analyses, several modules were highlighted for their proteins implicated in specific diseases. Module 2 and 6 were enriched for many aging diseases including those in the circulatory systems, immune mechanisms, and neurodegeneration. Together, our findings fill a gap of current aging research and provide mechanistic understanding of proteomic changes in CSF during a healthy lifespan and insights for brain aging and diseases.

α2-antiplasmin positively regulates endothelial-to-mesenchymal transition and fibrosis progression in diabetic nephropathy

BACKGROUND

Diabetic nephropathy (DN), is microvascular complication of diabetes causes to kidney dysfunction and renal fibrosis. It is known that hyperglycemia and advanced glycation end products (AGEs) produced by hyperglycemic condition induce myofibroblast differentiation and endothelial-to-mesenchymal transition (EndoMT), and exacerbate fibrosis in DN. Recently, we demonstrated that α2-antiplasmin (α2AP) is associated with inflammatory response and fibrosis progression.

METHODS

We investigated the role of α2AP on fibrosis progression in DN using a streptozotocin-induced DN mouse model.

RESULTS

α2AP deficiency attenuated EndoMT and fibrosis progression in DN model mice. We also showed that the high glucose condition/AGEs induced α2AP production in fibroblasts (FBs), and the reduction of receptor for AGEs (RAGE) by siRNA attenuated the AGEs-induced α2AP production in FBs. Furthermore, the bloackade of α2AP by the neutralizing antibody attenuated the high glucose condition-induced pro-fibrotic changes in FBs. On the other hand, the hyperglycemic condition/AGEs induced EndoMT in vascular endothelial cells (ECs), the FBs/ECs co-culture promoted the high glucose condition-induced EndoMT compared to ECs mono-culture. Furthermore, α2AP promoted the AGEs-induced EndoMT, and the blockade of α2AP attenuated the FBs/ECs co-culture-promoted EndoMT under the high glucose condition.

CONCLUSIONS

The high glucose conditions induced α2AP production, and α2AP is associated with EndoMT and fibrosis progression in DN. These findings provide a basis for clinical strategies to improve DN.

Hypofibrinolysis in type 2 diabetes and its clinical implications: from mechanisms to pharmacological modulation

A prothrombotic state is a typical feature of type 2 diabetes mellitus (T2DM). Apart from increased platelet reactivity, endothelial dysfunction, hyperfibrinogenemia, and hypofibrinolysis are observed in T2DM. A variety of poorly elucidated mechanisms behind impaired fibrinolysis in this disease have been reported, indicating complex associations between platelet activation, fibrin formation and clot structure, and fibrinolysis inhibitors, in particular, elevated plasminogen antigen inhibitor-1 levels which are closely associated with obesity. Abnormal fibrin clot structure is of paramount importance for relative resistance to plasmin-mediated lysis in T2DM. Enhanced thrombin generation, a proinflammatory state, increased release of neutrophil extracellular traps, elevated complement C3, along with posttranslational modifications of fibrinogen and plasminogen have been regarded to contribute to altered clot structure and impaired fibrinolysis in T2DM. Antidiabetic agents such as metformin and insulin, as well as antithrombotic agents, including anticoagulants, have been reported to improve fibrin properties and accelerate fibrinolysis in T2DM. Notably, recent evidence shows that hypofibrinolysis, assessed in plasma-based assays, has a predictive value in terms of cardiovascular events and cardiovascular mortality in T2DM patients. This review presents the current data on the mechanisms underlying arterial and venous thrombotic complications in T2DM patients, with an emphasis on hypofibrinolysis and its impact on clinical outcomes. We also discuss potential modulators of fibrinolysis in the search for optimal therapy in diabetic patients.

Endotheliopathy in COVID-19-associated coagulopathy: evidence from a single-centre, cross-sectional study

BACKGROUND

An important feature of severe acute respiratory syndrome coronavirus 2 pathogenesis is COVID-19-associated coagulopathy, characterised by increased thrombotic and microvascular complications. Previous studies have suggested a role for endothelial cell injury in COVID-19-associated coagulopathy. To determine whether endotheliopathy is involved in COVID-19-associated coagulopathy pathogenesis, we assessed markers of endothelial cell and platelet activation in critically and non-critically ill patients admitted to the hospital with COVID-19.

METHODS

In this single-centre cross-sectional study, hospitalised adult (≥18 years) patients with laboratory-confirmed COVID-19 were identified in the medical intensive care unit (ICU) or a specialised non-ICU COVID-19 floor in our hospital. Asymptomatic, non-hospitalised controls were recruited as a comparator group for biomarkers that did not have a reference range. We assessed markers of endothelial cell and platelet activation, including von Willebrand Factor (VWF) antigen, soluble thrombomodulin, soluble P-selectin, and soluble CD40 ligand, as well as coagulation factors, endogenous anticoagulants, and fibrinolytic enzymes. We compared the level of each marker in ICU patients, non-ICU patients, and controls, where applicable. We assessed correlations between these laboratory results with clinical outcomes, including hospital discharge and mortality. Kaplan-Meier analysis was used to further explore the association between biochemical markers and survival.

FINDINGS

68 patients with COVID-19 were included in the study from April 13 to April 24, 2020, including 48 ICU and 20 non-ICU patients, as well as 13 non-hospitalised, asymptomatic controls. Markers of endothelial cell and platelet activation were significantly elevated in ICU patients compared with non-ICU patients, including VWF antigen (mean 565% [SD 199] in ICU patients vs 278% [133] in non-ICU patients; p<0·0001) and soluble P-selectin (15·9 ng/mL [4·8] vs 11·2 ng/mL [3·1]; p=0·0014). VWF antigen concentrations were also elevated above the normal range in 16 (80%) of 20 non-ICU patients. We found mortality to be significantly correlated with VWF antigen (r = 0·38; p=0·0022) and soluble thrombomodulin (r = 0·38; p=0·0078) among all patients. In all patients, soluble thrombomodulin concentrations greater than 3·26 ng/mL were associated with lower rates of hospital discharge (22 [88%] of 25 patients with low concentrations vs 13 [52%] of 25 patients with high concentrations; p=0·0050) and lower likelihood of survival on Kaplan-Meier analysis (hazard ratio 5·9, 95% CI 1·9-18·4; p=0·0087).

INTERPRETATION

Our findings show that endotheliopathy is present in COVID-19 and is likely to be associated with critical illness and death. Early identification of endotheliopathy and strategies to mitigate its progression might improve outcomes in COVID-19.

FUNDING

This work was supported by a gift donation from Jack Levin to the Benign Hematology programme at Yale, and the National Institutes of Health.

Dynamics of Soluble Thrombomodulin and Circulating miRNAs in Patients with Atrial Fibrillation Undergoing Radiofrequency Catheter Ablation

Atrial fibrillation (AF) is the most common cardiac arrhythmia in the world and has a high risk of thromboembolism. The most effective approach, catheter ablation, requires evaluation by electrocardiography. The aim of our study was to investigate novel clinical markers that predict restoration of sinus rhythm (SR) after catheter ablation. Seventy-eight consecutive patients with AF underwent catheter ablation and were separated into 2 groups: restored SR and recurrent AF. The levels of 4 blood proteins (serum or plasma) and 3 mature microRNAs (miRNAs) and their primary miRNAs (pri-miRNAs) in serum were measured before and after ablation, and the associations between each parameter were analyzed statistically. Soluble thrombomodulin (s-TM) and plasminogen activator inhibitor-1 (PAI-1) levels increased above baseline after ablation in both the restored SR (s-TM 11.55 [2.92] vs 13.75 [3.38], P < .001; PAI-1 25.74 [15.25] vs 37.79 [19.56], P < .001) and recurrent AF (s-TM 10.28 [2.78] vs 11.67 [3.37], P < .001; PAI-1 26.16 [15.70] vs 40.74 [22.55], P < .001) groups. Levels of C-reactive protein and asymmetric dimethylarginine were not significantly changed. Pri-miR-126 levels significantly decreased after ablation in the recurrent AF group, but the other miRNAs and pri-miRNAs did not. The measurement of s-TM and pri-miR-126 in blood was a useful tool to reflect the condition of AF patients with catheter ablation.

Thrombomodulin and Thrombopoietin, Two Biomarkers of Hemostasis, Are Positively Associated with Adherence to the World Cancer Research Fund/American Institute for Cancer Research Recommendations for Cancer Prevention in a Population-Based Cross-Sectional Study

A pro-coagulative state is related to increased risk of cardiovascular diseases but also certain cancers. Since experimental and smaller human studies suggest that diet, physical activity, and body weight may all affect coagulation, we evaluated associations between these lifestyle factors and hemostatic biomarkers in a population-based study. Cross-sectional baseline data from 2267 randomly selected participants of EPIC-Heidelberg (age range 35–65 years) was used. Fibrinogen, glycoprotein IIb/IIIa, P-selectin, thrombomodulin (TM), and thrombopoietin (TPO) were measured in baseline plasma samples. A score reflecting adherence to the World Cancer Research Fund/American Institute for Cancer Research (WCRF/AICR) recommendations for cancer prevention was created. Associations between the WCRF/AICR score as well as its individual components and hemostatic biomarkers were analyzed by linear regression models. Multivariable-adjusted geometric means (95% confidence intervals) of TM and TPO were higher with greater adherence to the WCRF/AICR recommendations (TM, lowest vs. highest score category: 2.90 (2.7,3.1) vs. 3.10 (2.9,3.3) ng/mL, p_{linear trend} = 0.0001; TPO: 328 (302,356) vs. 348 (321,378) pg/mL, p_{linear trend} = 0.0007). These associations were driven by lower alcohol and meat consumption among persons with higher WCRF/AICR scores. Our results indicate that lifestyle factors favorably affect TM and TPO, two hemostatic factors implicated in chronic disease development.

Plasma proteomic signature of age in healthy humans

To characterize the proteomic signature of chronological age, 1,301 proteins were measured in plasma using the SOMAscan assay (SomaLogic, Boulder, CO, USA) in a population of 240 healthy men and women, 22-93 years old, who were disease- and treatment-free and had no physical and cognitive impairment. Using a p ≤ 3.83 × 10-5 significance threshold, 197 proteins were positively associated, and 20 proteins were negatively associated with age. Growth differentiation factor 15 (GDF15) had the strongest, positive association with age (GDF15; 0.018 ± 0.001, p = 7.49 × 10-56 ). In our sample, GDF15 was not associated with other cardiovascular risk factors such as cholesterol or inflammatory markers. The functional pathways enriched in the 217 age-associated proteins included blood coagulation, chemokine and inflammatory pathways, axon guidance, peptidase activity, and apoptosis. Using elastic net regression models, we created a proteomic signature of age based on relative concentrations of 76 proteins that highly correlated with chronological age (r = 0.94). The generalizability of our findings needs replication in an independent cohort.

Expression Profiling of Genes Related to Endothelial Cells Biology in Patients with Type 2 Diabetes and Patients with Prediabetes

Endothelial dysfunction appears to be an early sign indicating vascular damage and predicts the progression of atherosclerosis and cardiovascular disorders. Extensive clinical and experimental evidence suggests that endothelial dysfunction occurs in Type 2 Diabetes Mellitus (T2DM) and prediabetes patients. This study was carried out with an aim to appraise the expression levels in the peripheral blood of 84 genes related to endothelial cells biology in patients with diagnosed T2DM or prediabetes, trying to identify new genes whose expression might be changed under these pathological conditions. The study covered a total of 45 participants. The participants were divided into three groups: group 1, patients with T2DM; group 2, patients with prediabetes; group 3, control group. The gene expression analysis was performed using the Endothelial Cell Biology RT² Profiler PCR Array. In the case of T2DM, 59 genes were found to be upregulated, and four genes were observed to be downregulated. In prediabetes patients, increased expression was observed for 49 genes, with two downregulated genes observed. Our results indicate that diabetic and prediabetic conditions change the expression levels of genes related to endothelial cells biology and, consequently, may increase the risk for occurrence of endothelial dysfunction.

Associations Between Inflammatory Markers, Hemostatic Markers, and Microvascular Complications in 182 Chinese Patients With Type 2 Diabetes Mellitus

OBJECTIVE

To examine the associations between inflammatory markers, coagulation and fibrinolysis parameters, and microvascular complications in 182 Chinese patients with type 2 diabetes mellitus (T2DM) who sought treatment at a large hospital in Zhejiang province, China.

METHODS

We investigated the relationships of blood inflammatory markers with hemostatic markers in 87 patients with T2DM who did not have complications and 95 patients with T2DM who had microvascular complications.

RESULTS

C-reactive protein (CRP) and interleukin-6 (IL-6) were significantly correlated with fibrinogen, thrombin-antithrombin III complex (TAT III), plasminogen activator inhibitor-1 (PAI-1), von Willebrand factor (vWF), and coagulation factors (F) VII in patients with T2DM who had microvascular complications (P <.05). Based on logistic regression analysis, the highest-tertile groups of fibrinogen, FVII, and FVIII, corresponded to a greater risk of high CRP, whereas risk of high IL-6 was significantly greater in the groups with highest-tertile values for fibrinogen, FVII, TAT III, PAI-1, and activated protein C (APC).

CONCLUSIONS

Elevated levels of CRP and IL-6 might be associated with increased coagulability and a tendency towards thrombus formation in patients with T2DM who have microvascular complications.

Thrombomodulin domain 1 ameliorates diabetic nephropathy in mice via anti-NF-κB/NLRP3 inflammasome-mediated inflammation, enhancement of NRF2 antioxidant activity and inhibition of apoptosis

AIMS/HYPOTHESIS

Chronic inflammatory processes have been increasingly shown to be involved in the pathogenesis of diabetes and diabetic nephropathy. Recently, we demonstrated that a lectin-like domain of thrombomodulin (THBD), which is known as THBD domain 1 (THBDD1) and which acts independently of protein C activation, neutralised an inflammatory response in a mouse model of sepsis. Here, therapeutic effects of gene therapy with adeno-associated virus (AAV)-carried THBDD1 (AAV-THBDD1) were tested in a mouse model of type 2 diabetic nephropathy.

METHODS

To assess the therapeutic potential of THBDD1 and the mechanisms involved, we delivered AAV-THBDD1 (10(11) genome copies) into db/db mice and tested the effects of recombinant THBDD1 on conditionally immortalised podocytes.

RESULTS

A single dose of AAV-THBDD1 improved albuminuria, renal interstitial inflammation and glomerular sclerosis, as well as renal function in db/db mice. These effects were closely associated with: (1) inhibited activation of the nuclear factor κB (NF-κB) pathway and the NACHT, LRR and PYD domains-containing protein 3 (NLRP3) inflammasome; (2) promotion of nuclear factor (erythroid-derived 2)-like 2 (NRF2) nuclear translocation; and (3) suppression of mitochondria-derived apoptosis in the kidney of treated mice.

CONCLUSIONS/INTERPRETATION

AAV-THBDD1 gene therapy resulted in improvements in a model of diabetic nephropathy by suppressing the NF-κB-NLRP3 inflammasome-mediated inflammatory process, enhancing the NRF2 antioxidant pathway and inhibiting apoptosis in the kidney.

Exendin-4 restores glucolipotoxicity-induced gene expression in human coronary artery endothelial cells

Exendin-4, a stable GLP-1 receptor agonist, has been shown to stimulate insulin secretion. It has also been shown to exert beneficial effects on endothelial function that are independent of its glycemic effects. The molecular mechanisms underlying the protective actions of exendin-4 against diabetic glucolipotoxicity in endothelial cells largely remain elusive. We have investigated the long-term in vitro effect of palmitate or high glucose (simulating the diabetic milieu) and the role of exendin-4 on gene expression in human coronary artery endothelial cells. Gene expression profiling in combination with Western blotting revealed that exendin-4 regulates expression of a number of genes involved in angiogenesis, inflammation and thrombogenesis under glucolipotoxic conditions. Our results indicate that exendin-4 may improve endothelial cell function in diabetes through regulating expression of the genes, whose expression was disrupted by glucolipotoxicity. As endothelial dysfunction appears to be an early indicator of vascular damage, and predicts both progression of atherosclerosis and incidence of cardiovascular events, exendin-4 and possibly other incretin-based strategies may confer additional cardiovascular benefit beyond improved glycemic control.

The association of plasma fibrinogen concentration with diabetic microvascular complications in young adults with early-onset of type 2 diabetes

AIMS

Diabetic nephropathy is an important risk factor for cardiovascular diseases (CVD). The underlying etiology is not fully understood but may be related to changes in inflammatory and hemostatic markers with kidney disease. We investigated the associations of the markers with microvascular complications in Pima Indians (PI) with early-onset type 2 diabetes (T2DM).

METHODS

C-reactive protein, interleukine-6, fibrinogen, D-dimer, plasmin-antiplasmin complex and plasminogen activator inhibitor-1 were measured in 104 PI (age: 32+/-4 y) with diabetes and 59 (32+/-4 y) with fasting glucose <110 mg/dl and 2-h glucose <140 mg/dl. Urine albumin to creatinine ratio (ACR) was used as marker of nephropathy. Severity of retinopathy was classified in the worse eye by direct ophthalmoscopy as none, background and proliferative.

RESULTS

Of these markers, only fibrinogen was associated with ACR (r=0.25, p<0.01). After adjustment for age, sex, percentage Pima heritage, smoking status, diabetes duration, blood pressure and use of aspirin, antihypertensive and antihyperglycemic agents, general linear models (with natural log-transformed values of fibrinogen and ACR as dependent and independent variables, respectively) revealed that a one percent increase in ACR would yield a 0.02% increase in the fibrinogen (beta=0.02, p<0.05). Plasma fibrinogen was also significantly increased with severity of diabetic retinopathy (p<0.05).

CONCLUSIONS

Increased plasma fibrinogen concentration was associated with diabetic microvascular disease, in particular with nephropathy. This may help to explain the etiologic link between nephropathy and CVD.

Accumulation of risk factors enhances the prothrombotic state in atrial fibrillation

BACKGROUND

The present study was conducted to investigate the relation between the accumulation of the risk factors of thromboembolism and the levels of hemostatic markers in patients with nonvalvular atrial fibrillation (NVAF).

METHODS

Five hundred ninety-one NVAF patients and 129 control subjects were categorized into low, moderate or high risk of thromboembolism, according to CHADS(2) index. One point each was given to patients with advanced age (> or =75 years), hypertension, congestive heart failure, and diabetes mellitus, and 2 points, to those with prior ischemic stroke or transient ischemic attack. Patients with CHADS(2) score of 0, 1 or 2, and > or =3 were classified as low, moderate and high risk, respectively. Levels of hemostatic markers (platelet factor 4, beta-thromboglobulin, prothrombin fragment F1+2 and D-dimer) were determined.

RESULTS

Of 591 patients with NVAF, 302 were treated with warfarin (mean international normalized ratio 1.88). D-dimer levels increased as the risk level increased irrespective of warfarin use. Particularly, NVAF patients without receiving warfarin (n=289) had significantly higher D-dimer levels than control patients (e.g., for high risk patients, 175+/-144 vs 75+/-87 ng/ml, p<0.001), while NVAF patients receiving warfarin had intermediate levels (136+/-156 ng/ml). F1+2 levels increased as the risk level increased, and were significantly suppressed by warfarin. Levels of markers of platelet activation (platelet factor 4 and beta-thromboglobulin) were increased in NVAF patients but not affected by the risk level.

CONCLUSION

Coagulation and fibrinolytic activity is increased along with the accumulation of the risk factors of thromboembolism in NVAF patients.

Decreased plasma soluble thrombomodulin levels as a risk factor for pulmonary thromboembolism

OBJECTIVE

To observe the changes of the plasma soluble thrombomodulin (sTM) concentrations in patients with pulmonary thromboembolism (PTE) and assess the association between plasma sTM concentration and the risk of PTE.

PATIENTS AND METHODS

We measured plasma concentrations of sTM, protein C (PC) and protein S (PS) and examined the association between those plasma markers and the risk of PTE in 72 selected PTE patients and 70 controls.

RESULTS

Significant difference was identified in plasma sTM level between overall PTE patients and controls. Female PTE patients had statistically lower sTM concentrations than male patients. A positive linear correlation was found between plasma sTM concentration and age in female patients. Decreased plasma sTM concentration was associated with a continuously and progressively increased risk for PTE in women. The concentrations of plasma PC and PS did not differ between groups and no significant quantitative association was identified between the risk of PTE and the levels of plasma PC or PS.

CONCLUSION

Decreased plasma sTM concentration is associated with an increased risk of PTE in women.

Mild peripheral neuropathy prevents both leg muscular ischaemia and activation of exercise-induced coagulation in Type 2 diabetic patients with peripheral artery disease

AIM

To study the influence of peripheral neuropathy on intermittent claudication in patients with Type 2 diabetes (T2DM).

METHODS

Twenty-five patients with T2DM were grouped according to the ankle/brachial index (ABI): 10 with ABI > 0.9 without peripheral artery disease (PAD; group T2DM) and 15 with ABI < 0.9 with PAD (group T2DM + PAD). Twelve individuals without T2DM with PAD (group PAD without T2DM) were also enrolled. Tests for peripheral neuropathy were performed in all patients. ABI, rate pressure product, prothrombin fragments 1 + 2 (F1+2), thrombin-anti-thrombin complex (TAT), and d-dimer were measured before and after a treadmill test. During exercise both initial and absolute claudication distance and electrocardiogram readings were recorded.

RESULTS

We found mild peripheral neuropathy in 20% of group T2DM and 46.7% of group T2DM + PAD (P < 0.01). After exercise, the rate pressure product increased in each group; ABI fell in T2DM + PAD (P < 0.0001) and in PAD without T2DM (P = 0.0005); the fall was greater in the latter group. Initial and absolute claudication distances were similar in PAD patients. In group T2DM + PAD, absolute claudication distance was longer in the subgroup without peripheral neuropathy (P < 0.05), whereas ABI and rate pressure products were similar. F1+2 values at rest were higher in group T2DM + PAD. After exercise, F1+2 values and TAT increased only in group PAD without T2DM.

CONCLUSION

Only group PAD without T2DM experienced muscular ischaemia, whereas group T2DM + PAD did not. Mild peripheral neuropathy may have prevented them from reaching the point of muscular ischaemia during the treadmill test, because they stopped exercising with the early onset of pain. Reaching a false absolute claudication distance may induce ischaemic preconditioning. These findings suggest a possible protective role of mild peripheral neuropathy in T2DM patients with intermittent claudication, by preventing further activation of coagulation during treadmill testing.

Stimulation of the peroxisome proliferator-activated receptor γ (PPARγ) and the expression of selected blood monocyte cytokine genes in diabetic macroangiopathy

Monocytes and macrophages play a key role in the progression of atheromatous changes. The peroxisome proliferator-activated receptor gamma (PPAR gamma) can limit macroangiopathy through the control of cytokine transcription. The objectives of this study were to examine the influence of PPAR gamma and its agonist (rosiglitazone) on the TNFalpha, IL-6, IL-8 and IL-10 gene expression in monocytes of patients with diabetic macroangiopathy and to analyse obtained results in context of selected atherogenic factors ant direct indicators of endothelial lesion. TNFalpha, IL-6, IL-8, IL-10 and PPAR gamma gene expression was assessed in peripheral blood monocytes in 45 patients with type 2 diabetes before and following 22 weeks of rosiglitazone therapy (real-time PCR [Applied Biosystems]). As indicators of endothelial lesion, concentration of thrombomodulin (immunoassay [Diagnostica Stago]) and amount of circulating blood endothelial cells (immunofluorescence method with MoAb CLB-HEC19) were determined. Following rosiglitazone therapy, a statistically significant downward tendency of TNFalpha (p=0.026) and IL-8 (p=0.008) gene expression was noted. Before and following rosiglitazone treatment, PPAR gamma, IL-6 and IL-10 gene expression was undetectable in studied monocytes in vivo. In conclusion, TNFalpha and IL-8 play an important role in monocyte atherogenic activity. Rosiglitazone reduces monocyte proinflammatory readiness by influencing the expression of selected atherogenic cytokines (PPAR gamma-independent pathway).

Mathematical modeling of blood coagulation cascade: kinetics of intrinsic and extrinsic pathways in normal and deficient conditions

A mathematical model has been developed to simulate the generation of thrombin through intrinsic and extrinsic pathways. The time course of clotting factor activation during coagulation was calculated, and the sensitivity of the kinetics due to a decrease or deficiency in the concentrations of coagulation proteins or their activities was studied. The model gives reasonable predictions without the adjustment of any parameter values. The calculated clotting time was approximately 44 s for the intrinsic pathway and approximately 8.6 s for the extrinsic pathway using normal protein concentrations in plasma. Various prolonged clotting times were observed in different factor-deficient disorders using this model.

The association between seated immobility and local lower-limb venous coagulability in healthy adult volunteers: a simulation of prolonged travel immobility

This is the first study to examine the hypothesis that prolonged sitting is associated with procoagulant changes in the local lower-limb venous system. A comparison was made with upper-limb venous changes. Changes in markers of thrombin generation, fibrinolysis, endothelial perturbation and haemoconcentration were analysed as 10 healthy adult male participants sat for 8 h. The change in foot volume was estimated. Subjective venous thromboembolism assessment was undertaken hourly, along with 2-week and 4-week safety follow-up for clinical events. Expected increases in median prothrombin fragments 1 and 2, thrombin-antithrombin complex and D-dimer were not observed in either limb. An increase greater than 45% in the median tissue plasminogen activator and plasminogen activator-1 molar ratio (t-PA/PAI-1), and a decrease greater than 15% in median soluble thrombomodulin were noted in both limbs. Median haematocrit decreased minimally (1%) in the lower limbs, while the foot volume increased by 4%. Subjects experienced vague symptoms after 6 h of sitting, but none developed symptomatic venous thromboembolism. Upper and lower-limb changes in biomarkers did not correlate, except those in t-PA/PAI-1 ratio and plasminogen activator-1. Significant correlation was found between changes in the lower-limb t-PA/PAI-1 ratio and right foot volume. This study originally reveals that even in the lower limbs, prolonged daytime cramped sitting is not associated with significant procoagulant changes in healthy adult male volunteers, and confirms a previous observation that local lower-limb venous changes are not identically reflected in the upper limbs.

Prolonged seated immobility-associated venous coagulability in a factor V Leiden heterozygote: a case-comparative study

Prolonged sitting and thrombophilia may compound the risk of venous thromboembolism. In order to investigate suspected local lower limb venous procoagulant changes associated with prolonged sitting-induced venous stasis in a man heterozygous for factor V Leiden (participant X), we qualitatively compared venous coagulability in lower and upper limb plasma in this participant and three other male Caucasians over 8 h of sitting. Of the four participants, participant X had the highest baseline values of prothrombin fragments 1 and 2, thrombin-antithrombin III complexes, tissue plasminogen activator, plasminogen activator inhibitor 1, D-dimer and soluble thrombomodulin. Over time, in participant X, venous prothrombin fragments 1 and 2, thrombin-antithrombin III complexes, and soluble thrombomodulin decreased in both limbs; D-dimer decreased in the lower limbs but increased in the upper limbs; the tissue plasminogen activator/plasminogen activator inhibitor 1 molar ratio increased in both limbs; and minimal changes were noted in haematocrit. A foot volume increase was associated with vague symptoms towards the end of the study. Overall, these changes were similar to those observed in other participants. It is concluded from this case comparison that prolonged sitting of 8 h duration under normal atmospheric conditions did not result in local, as well as systemic, procoagulant haemostatic responses in a heterozygote for factor V Leiden when compared with other healthy volunteers. However, this observed, possibly adaptive, response is more likely to be compromised in factor V Leiden subjects during continued or increased venous endothelial stress or in the presence of other venous thromboembolism risk factors.

Enhanced soluble CD40L in patients with the metabolic syndrome: Relationship with in vivo thrombin generation

AIMS/HYPOTHESIS

The metabolic syndrome is associated with proinflammatory and prothrombotic states. This study was designed to assess the behaviour of soluble CD40 ligand (sCD40L) and prothrombin fragment F (1+2), a marker of thrombin generation, in patients with the metabolic syndrome.

METHODS

We investigated 106 patients with the metabolic syndrome, diagnosed according to the ATPIII report, and 104 subjects without the metabolic syndrome.

RESULTS

Plasma values of sCD40L and F (1+2) were higher in patients with the metabolic syndrome (4.11+/-1.64 vs 2.61+/-0.89 ng/ml and 1.54+/-0.49 vs 0.87+/-0.21 nmol/l, respectively; p < 0.001) and were significantly correlated (r = 0.925, p < 0.001). Stepwise multiple linear regression analysis showed that sCD40L was significantly associated with F (1+2), female sex and waist circumference.

CONCLUSIONS/INTERPRETATION

Patients with the metabolic syndrome have enhanced values of plasma sCD40L and F (1+2). The study provides further insight into the relationship between metabolic syndrome, inflammation and thrombosis.

Coagulation and fibrinolysis parameters in type 2 diabetic patients with and without diabetic vascular complications

OBJECTIVES

To investigate the markers of endogenous coagulation/fibrinolysis and vascular endothelial cell function, and to assess the relationships between hemostatic parameters and diabetic vascular complications in type 2 diabetic patients.

MATERIALS AND METHODS

Coagulation and fibrinolysis parameters were measured in 92 type 2 diabetic patients (43 male, 49 female, mean age 50.1 +/- 13.4 years) with (n = 44) and without (n = 48) vascular diabetic complications, and in 40 nondiabetic healthy subjects (20 male, 20 female, mean age 49.8 +/- 15.1 years). Common lipid parameters were also measured.

RESULTS

The plasma levels of fibrinogen, antithrombin III (AT III), plasminogen activator inhibitor-1 (PAI-1), von Willebrand factor (vWF) activity and prothrombin time were found to be significantly increased in the type 2 diabetic patients compared with the healthy subjects. Glycosylated hemoglobin lc was inversely correlated with plasma protein S and activated prothrombin time. Protein C and S activities were positively correlated with plasma vWF activity, and were negatively correlated with plasma t-PA levels. vWF activity was negatively correlated with plasma t-PA levels. AT III levels were positively correlated with plasma total cholesterol levels, plasma low density lipoprotein cholesterol levels, plasma triglycerides and D-dimer levels. Plasma PAI-1 levels and factor V activity in diabetic patients with microvascular complications were significantly higher than those of the diabetic patients without microvascular complications. The plasma PAI-1 and platelet count were increased in patients with diabetic retinopathy compared with the diabetic patients without retinopathy. Plasma PAI-1 levels and factor VII activity were significantly higher in the diabetic patients with nephropathy than in diabetic patients without nephropathy. Plasma concentrations of fibrinogen and PAI-1 were significantly higher in the diabetic patients with neuropathy than the diabetic patients without neuropathy.

CONCLUSIONS

The data demonstrated that patients with type 2 diabetes mellitus had a hypercoagulable state and hypofibrinolysis, thereby indicating that activation of coagulation with a reduced fibrinolytic activity may contribute to the increased risk of vascular disease in type 2 diabetic patients.

The profibrinolytic effect of plasma thrombomodulin in factor XI deficiency and its implications in hemostasis

Bleeding tendency in factor (F)XI deficiency may result from premature clot lysis due to insufficient thrombin activatable fibrinolysis inhibitor (TAFI) activation. Thrombomodulin (TM), upon binding to thrombin, is capable of modulating TAFI activation. In this study, we investigated the effects of plasma TM on fibrinolysis in FXI-deficient patients. A clot lysis assay showed the defective down-regulation of fibrinolysis in FXI-deficient patients as compared with normal controls. To evaluate the effects of plasma TM on fibrinolysis, a monoclonal anti-TM IgG was preincubated with plasma for 30 min. The presence of anti-TM IgG significantly prolonged the clot lysis times both in the FXI-deficient and normal plasma, indicating that plasma TM stimulated fibrinolysis. Furthermore, the presence of anti-TM IgG not only reduced protein C activation, but also increased thrombin generation and TAFI activation. The profibrinolytic effect of plasma TM was inhibited in the assay by including either a monoclonal anti-TAFI IgG or a specific TAFI inhibitor--carboxypeptidase inhibitor (CPI). Our results indicate that the impaired thrombin generation in FXI-deficient patients leads to the defective down-regulation of fibrinolysis, and that plasma TM stimulates fibrinolysis through APC pathway which inhibits TAFI activation. The profibrinolytic effect of plasma TM may contribute to the bleeding tendency observed in some FXI-deficient patients.

Urinary albumin excretion is correlated to fibrinogen levels and protein S activity in patients with type 1 diabetes mellitus without overt diabetic nephropathy

The aim of the study was to test the hypothesis that in diabetic patients without overt nephropathy there may be a correlation between the activity of natural anticoagulant proteins and glomerular dysfunction. Assays for functional activity of proteins S and C, measurements of urinary albumin excretion, lipid parameters and haemoglobin A1c were performed in 91 patients with type 1 diabetes mellitus and 85 patients with type 2. Patients with type 1 diabetes and microalbuminuria had significantly higher mean age (44.1 +/- 10.9 vs. 37.9 +/- 12.7 years; p<0.05), fibrinogen level (3.75 +/- 1.0 vs. 3.21 +/- 0.8 g/l; p<0.01), protein S activity (92.3 +/- 17.6 vs. 84.5 +/- 15.5%; p<0.05) and higher prevalence of retinopathy (p<0.01) and macrovascular disease (p<0.01) than those with normoalbuminuria. Albumin excretion was significantly correlated to age (r=0.25, p<0.05), fibrinogen level (r=0.39, p<0.01), protein S activity (r=0.27; p<0.05), total cholesterol (r=0.23; p<0.05), apoprotein B (r=0.22; p<0.05), retinopathy (r=0.33; p<0.01) and macrovascular disease (r=0.33; p<0.01). Patients with type 2 diabetes mellitus and microalbuminuria had significantly higher apoprotein B levels (1.17 +/- 0.3 vs. 1.06 +/- 1.2 mg/dl; p<0.05) than those with normoalbuminuria, and apoprotein B was significantly correlated to albumin excretion (r=0.22; p<0.05). In a multivariate model of type 1 diabetes mellitus with fibrinogen, protein S and C activity, cholesterol, triglycerides, haemoglobin A1c, retinopathy, and macrovascular disease as independent parameters (r=0.53; p<0.003), there was significant independent correlation of fibrinogen (beta=0.28; p<0.01), protein S activity (beta=0.27; p<0.05) and retinopathy (beta=0.21; p<0.01) with albumin excretion. We conclude that in type 1 diabetes, relative elevation of fibrinogen level and protein S activity appear in the early stages of development of diabetic nephropathy, and may be related to the pathogenesis of diabetic kidney disease.

Plasma interleukin-6 is associated with coagulation in poorly controlled patients with Type 2 diabetes

AIMS

We investigated the relationship between interleukin (IL)-6 and coagulation, i.e. whether changes in the plasma IL-6 are associated with those in coagulation markers (D dimer and fibrinogen) after glycaemic control with sulphonylurea or insulin in poorly controlled patients with Type 2 diabetes.

METHODS

We studied 42 patients with Type 2 diabetes, including 19 subsequently treated with sulphonylurea, 23 treated with insulin and 48 control subjects. All patients were in poor glycaemic control and were hospitalized for 3 weeks. At the beginning and end of treatment, we measured plasma concentrations of IL-6, fibrinogen, and D dimer.

RESULTS

Plasma concentrations of IL-6 and D dimer were significantly higher in diabetic patients than in controls (P<0.0001 for both). In all patients with diabetes, the plasma concentration of IL-6 decreased significantly (P<0.001) after treatment. Changes in the plasma IL-6 during hospitalization were positively correlated with those in plasma D dimer and fibrinogen (r=0.664, P<0.0001; r=0.472, P=0.0042, respectively). Treatment with sulphonylurea or insulin caused a similar fall in the plasma IL-6 concentration with a concomitant decrease in the BMI and an equal improvement in glycaemia.

CONCLUSIONS

In poorly controlled patients with Type 2 diabetes, plasma IL-6 concentrations were reduced significantly even by short-term metabolic control. As changes in the plasma concentrations of D dimer are related to plasma IL-6, plasma IL-6 may reflect a pro-coagulant as well as an inflammatory state in patients with Type 2 diabetes.

Thrombomodulin deficiency in human diabetic nerve microvasculature

Human diabetic neuropathy is multifactorial in etiology, with ischemia as a final common pathology. Although impaired vascular endothelial cell function in diabetic microvascular injury is established, the role of thrombomodulin (TM)-dependent protein C antithrombotic mechanism in the pathogenesis of neuropathy is unclear. This neuropathologic case-control study investigated whether vascular endothelial TM expression is deficient in peripheral nerve microvessels in diabetic neuropathy. Sural nerve biopsies from 7 patients with diabetic neuropathy and 10 with axonal neuropathy without vasculopathy were immunostained with anti-TM and anti-von Willebrand factor (vWF; an endothelial cell marker) antibodies. The proportion of TM-positive microvessels was expressed relative to total vWF-staining vessels, according to vessel caliber and regional distribution within the nerve. In diabetic nerves compared with reference controls, the proportion of TM-positive endoneurial microvessels was 15-fold lower (0.02 vs. 0.30 in diabetic nerves vs. controls, P < 0.004), and the proportion of small-caliber epineurial microvessels was 10-fold lower (0.04 vs. 0.43, P < 0.001). No TM expression was detected at the perineurium in diabetic or control nerves. We demonstrate a substantial reduction of vascular endothelial TM expression throughout human diabetic neuropathy. These findings suggest that an impaired native TM-dependent protein C antithrombotic mechanism may contribute to microvascular ischemia in the pathogenesis of diabetic neuropathy.

Association of postmenopausal hormone replacement therapy with carotid atherosclerosis and soluble thrombomodulin: the vascular aging (EVA) study. Etude du Vieillissement Artériel

Hormone replacement therapy (HRT) may reduce atherosclerosis among postmenopausal women, partly by reducing vascular endothelium damage. We have tested this hypothesis by evaluating the association of HRT with firstly, carotid intima media thickness (IMT) and plaques, and secondly, with endothelial cell damage, indicated by soluble thrombomodulin (sTM). Then, we tested the association between the two markers of atherosclerosis and the levels of sTM. Among 747 postmenopausal women included into the EVA study, we compared 154 HRT users (including 80% transdermal treatment) with 593 never users. Carotid IMT and plaques were measured with B-mode ultrasonography and sTM with ELISA. At least one plaque was detected among 13.6% of HRT users and 27.3% of never users. After adjustment for confounding factors, the odds ratio for the presence of plaque was 0.45 (95% confidence interval, 0.25-0.78, P=0.005) in HRT users in comparison with nonusers. HRT users had a slightly lower crude mean IMT than nonusers, but the difference was not significant. sTM was positively associated with mean IMT (P for trend=0.001) but not with plaques. Finally, estrogen users had a lower sTM level than nonusers (difference 0.14 ng/ml, P=0.03). As HRT was associated with sTM and plaques, but not with IMT, while sTM was only associated with IMT, our hypothesis was not confirmed. This suggests that the possible beneficial effects of HRT on atherosclerosis may not go through the endothelial cell damage assessed by plasma thrombomodulin.