Decrements in the Thrombin Activatable Fibrinolysis Inhibitor (TAFI) Levels in Association with Orlistat Treatment in Obesity

Obesity, thrombosis, venous disease, lymphatic disease, and lipedema: An obesity medicine association (OMA) clinical practice statement (CPS) 2023

Background

This Obesity Medicine Association (OMA) Clinical Practice Statement (CPS) is intended to provide clinicians with an overview on obesity, thrombosis, venous disease, lymphatic disease, and lipedema.

Methods

The scientific support for this CPS is based upon published citations, clinical perspectives of OMA authors, and peer review by the Obesity Medicine Association leadership.

Results

Topics in this CPS include obesity, thrombosis, venous disease, lymphatic disease, and lipedema. Obesity increases the risk of thrombosis and cardiovascular disease via fat mass and adiposopathic mechanisms. Treatment of thrombosis or thrombotic risk includes healthful nutrition, physical activity, and the requisite knowledge of how body weight affects anti-thrombotic medications. In addition to obesity-related thrombotic considerations of acute coronary syndrome and ischemic non-hemorrhagic stroke, this Clinical Practice Statement briefly reviews the diagnosis and management of clinically relevant presentations of deep vein thromboses, pulmonary embolism, chronic venous stasis, varicose veins, superficial thrombophlebitis, lipodermatosclerosis, corona phlebectatica, chronic thromboembolic pulmonary hypertension, iliofemoral venous obstruction, pelvic venous disorder, post-thrombotic syndrome, as well as lymphedema and lipedema - which should be included in the differential diagnosis of other edematous or enlargement disorders of the lower extremities.

Conclusions

This Obesity Medicine Association (OMA) Clinical Practice Statement (CPS) on obesity, thrombosis, and venous/lymphatic disease is one of a series of OMA CPSs designed to assist clinicians in the care of patients with the disease of obesity.

Serum thrombin-activatable fibrinolysis inhibitor levels and its relation with pathogenesis and bleeding and prognosis in patients with Crimean Congo hemorrhagic fever

Crimean-Congo hemorrhagic fever (CCHF) is a viral hemorrhagic fever, which is common in Turkey and globally. The pathogenesis of coagulation disorders, which is seen in viral hemorrhagic fevers remains to be elucidated. Thrombin-activatable fibrinolysis inhibitor (TAFI) has a key role in this process In this study, we aimed to evaluate whether TAFI levels contributed to bleeding and whether it is related to prognosis in CCHF patients. Eighty-four patients older than 15 years of age, who were admitted to our hospital who had positive immunoglobulin M (enzyme-linked immunosorbent assay [ELISA]) and/or polymerase chain reaction test results for CCHF between 2009 and 2010, were included in the study. The control group included 30 healthy adults. The plasma TAFI levels were compared between patients and controls, and also between patients with bleeding and no bleeding, and between patients with mild-moderate and severe disease. The mean TAFI levels were lower in patients (mean: 87.82 ng/ml, median: 61.69 ng/ml (interquartile range [IQR] 30.49-537.95) than controls (mean: 313.5 ng/ml with a median: 338.5 ng/ml (IQR 182-418). However, median TAFI levels were significantly higher in patients with bleeding compared to those without bleeding (78.99 and 50.28 ng/ml, respectively; p = 0.032). Median IQR TAFI levels were similar between patients with mild-moderate and severe disease (64.72 (41.37-113.85), and, 58.66 (42.44-118.93) ng/ml, respectively; p = 0.09) and survivors and nonsurvivors (86.14 ± 77.98 and 103.48 ± 69.92, respectively; p = 0.3). Although TAFI levels were lower in the patients with CCHF compared to healthy controls, it does not seem to be a major player in the prognosis.

New insights into the role of adipose tissue in thrombosis

Central obesity is independently associated with an elevated risk of cardiovascular disease, particularly thrombotic complications. Increasing data supports a link between excess body weight and the risk to suffer acute myocardial infarction, stent thrombosis after percutaneous interventions, ischemic stroke and vein thrombosis. Experimental and in vitro data have provided insights as to the mechanisms currently presumed to increase the thrombotic risk in obese subjects. Obesity is characterized by a chronic low grade inflammation and systemic oxidative stress that eventually damage the endothelium losing its antithrombotic properties. Obesity also stimulates the expression of leptin and attenuates adiponectin release, a protective adipokine. Although the contribution of adipokines to thrombosis has been questioned, recent work has suggested that they enhance platelet activation and, although to a lesser extent, induce the coagulation cascade through tissue factor (TF) expression. Increased body weight also impairs platelet sensitivity to insulin signaling and enhances the production of bioactive isoprostanes further promoting platelet reactivity. Finally, obese subjects have shown elevated circulating levels of von Willebrand factor, TF, factor VII and VIII, and fibrinogen, favoring a mild-to-moderate hypercoagulable state, and, on the other hand, increased secretion of plasminogen activator inhibitor (PAI)-1 and thrombin activatable fibrinolysis inhibitor (TAFI) contributing to impair the fibrinolytic system. In the present review, we provide an overview of the impact of excess body weight on thrombosis. We will focus on the link between dysfunctional adipose tissue and endothelial damage, platelet reactivity, enhanced coagulation and impaired fibrinolysis; mechanisms currently recognized to increase arterial thrombotic risk in obese subjects.

Hemostasis in Hypothyroidism and Autoimmune Thyroid Disorders

CONTEXT

There are contradictory results on the effect of hypothyroidism on the changes in hemostasis. Inadequate population-based studies limited their clinical implications, mainly on the risk of venous thromboembolism (VTE). This paper reviews the studies on laboratory and population-based findings regarding hemostatic changes and risk of VTE in hypothyroidism and autoimmune thyroid disorders.

EVIDENCE ACQUISITION

A comprehensive literature search was conducted employing MEDLINE database. The following words were used for the search: Hypothyroidism; thyroiditis, autoimmune; blood coagulation factors; blood coagulation tests; hemostasis, blood coagulation disorders; thyroid hormones; myxedema; venous thromboembolism; fibrinolysis, receptors thyroid hormone. The papers that were related to hypothyroidism and autoimmune thyroid disorder and hemostasis are used in this review.

RESULTS

Overt hypothyroidism is more associated with a hypocoagulable state. Decreased platelet count, aggregation and agglutination, von Willebrand factor antigen and activity, several coagulation factors such as factor VIII, IX, XI, VII, and plasminogen activator-1 are detected in overt hypothyrodism. Increased fibrinogen has been detected in subclinical hypothyroidism and autoimmune thyroid disease rendering a tendency towards a hypercoagulability state. Increased factor VII and its activity, and plasminogen activator inhibitor-1 are among several findings contributing to a prothrombotic state in subclinical hypothyroidism.

CONCLUSIONS

Overt hypothyroidism is associated with a hypocoagulable state and subclinical hypothyroidism and autoimmune thyroid disorders may induce a prothrombotic state. However, there are contradictory findings for the abovementioned thyroid disorders. Prospective studies on the risk of VTE in various levels of hypofunctioning of the thyroid and autoimmune thyroid disorders are warranted.

Bariatric patients have plasmatic hypercoagulability and systemic upregulation of heme oxygenase activity

Morbid obesity is associated with significant thrombophilia. Of interest, adipocytes obtained from obese patients have increased heme oxygenase (Hmox) activity, the endogenous enzyme responsible for carbon monoxide (CO) production. Given that CO enhances plasmatic coagulation, we determined whether morbidly obese patients undergoing bariatric surgery had an increase in endogenous CO and plasmatic hypercoagulability. CO was determined by noninvasive pulse oximetry measurement of carboxyhemoglobin (COHb). A thrombelastographic method to assess plasma coagulation kinetics and formation of carboxyhemefibrinogen (COHF) was utilized. Nonsmoking bariatric patients (n = 20, BMI 47 ± 8 kg/m, mean ± SD) had abnormally increased COHb concentrations of 2.7 ± 1.9%, indicative of Hmox upregulation. When coagulation kinetics of these bariatric patients were compared with values obtained from normal individuals' (n = 30) plasma, 70% (95% confidence interval 45.7-88.1%) had abnormally great velocity of clot formation, abnormally large clot strength, and COHF formation. Future investigation of Hmox-derived CO in the pathogenesis of obesity-related thrombophilia is warranted.

Levels of thrombin activatable fibrinolysis inhibitor in gestational diabetes mellitus

Thrombin-activatable fibrinolysis inhibitor (TAFI) is a procarboxypeptidase, which is synthesised in liver and activated by thrombin and the thrombin-thrombomodulin complex. TAFI suppresses fibrinolysis by removing carboxy-terminal lysine residues from partially degraded fibrin. In this study we aimed to assess the circulating levels of TAFI antigen, 'a fibrinolytic parameter' in women with gestational diabetes (GDM). Thirty-four pregnant women with GDM and 50 pregnant women with normal glucose tolerance were included in the study. Plasma TAFI antigen levels were significantly higher in pregnant women with GDM when compared with controls. Increased TAFI levels may contribute to the decreased fibrinolytic potency, causing a thrombophilic state. GDM is regarded as a specific form of diabetes, and it could in addition be a predictor of type 2 diabetes mellitus in the future and the risk of complications due to hypercoagulability increases in this disease. Increased TAFI levels may also have a role in increased risk of hypercoagulability.

Evidence that fibrinolytic changes in paediatric obesity translate into a hypofibrinolytic state: relative contribution of TAFI and PAI-1

Paediatric obesity, like adulthood obesity, is associated with an increase of fibrinolysis inhibitors. No study, however, has evaluated the impact of these changes on plasma fibrinolytic capacity. We investigated plasma fibrinolysis and the role therein of the fibrinolytic changes associated with obesity in 59 obese children (body mass index > 95th percentile) and 40 matched controls. Fibrinolysis was investigated by measuring 1) the plasma levels of relevant fibrinolytic factors; 2) the in vitro fibrinolytic capacity under different conditions, using a microplate plasma clot lysis assay; 3) the circulating levels of markers of clotting and fibrinolysis activation. Plasminogen activator inhibitor 1 (PAI-1), total thrombin activatable fibrinolysis inhibitor (TAFI) and fibrinogen levels were higher in obese children as compared to controls (p<0.01). Plasma clots from obese children lysed significantly slower than control clots when exposed to exogenous plasminogen activator, indicating a greater resistance to fibrinolysis. By the use of a selective inhibitor of activated TAFI and by regression analyses we found that fibrinolysis resistance in obese samples was attributable to PAI-1 increase and to enhanced TAFI activation. The ratio between the circulating levels of D-dimer and thrombin-antithrombin complex, a marker of in vivo fibrinolysis, was significantly lower in obese children, suggesting a reduced fibrinolytic efficiency. These data indicate that paediatric obesity is associated with a hypofibrinolytic state which might contribute to the increased thrombotic risk associated with this condition.

Thrombin-Activatable Fibrinolysis Inhibitor (TAFI) Antigen and Activity Assay in Patients With Primary Hypothyroidism

Hypothyroidism causes a tendency for cardiovascular diseases. It was recently shown that thrombin-activatable fibrinolysis inhibitor (TAFI) attenuates fibrinolysis and also fibrin-plasminogen interaction by the removal of lysine and arginine residues from fibrin monomers. The aim of this study was to determine the effects of overt hypothyroidism on the levels of TAFI antigen (TAFI Ag) and TAFI activity (TAFIa). Thirty-one overt primary hypothyroid patients and age- and gender-matched 25 healthy controls were enrolled in the study. Patients were treated with L-thyroxine after the collection of blood samples. Thyroid functions were reevaluated following the achievement of euthyroid status. Thrombin-activatable fibrinolysis inhibitor Ag, tissue plasminogen activator (t-PA), and plasminogen activator inhibitor 1 (PAI-1) levels were measured with the enzyme-linked immunosorbent assay (ELISA). Thrombin-activatable fibrinolysis inhibitor activity was assessed with the chromogenic assay. Thrombin-activatable fibrinolysis inhibitor Ag (1.63% ± 0.42% vs 1.32% ± 0.36%, P < .01) and TAFIa (14.2 ± 4.12 vs 11.6 ± 3.49 μg/mL, P < .05) levels were elevated in hypothyroid patient compared to controls. Plasminogen activator inhibitor 1 and t-PA levels were not significantly different between both groups. In hypothyroid patients, TAFI Ag levels were correlated with free T4 (r = -.373, P < .05) and thyroid-stimulating hormone (TSH) levels (r = .748, P < .001). Regression analysis showed that TSH levels were predictors of TAFI Ag levels (P < .001, β =.671, 95% confidence interval [CI]: 0.008-0.017). Following L-thyroxine treatment, TAFI Ag (1.63% ± 0.42%, 1.34% ± 0.33%, P < .05) and TAFIa (14.2 ± 4.12 μg/mL, 12.0 ± 2.77 μg/mL, P < .05) levels were significantly decreased, but t-PA and PAI-1 levels remained unchanged. This results point out that the fibrinolytic activity was decreased in hypothyroid patients, and therefore the achievement of euthyroid status is important in ameliorating the increased risk of cardiovascular disease.

Gestational diabetes has no additional effect on plasma thrombin-activatable fibrinolysis inhibitor antigen levels beyond pregnancy

Pregnancy is a prothrombotic condition with increased levels of several circulating coagulation factors. Decreased fibrinolytic activity has been shown in gestational diabetes. Gestational diabetes has been found to be associated with higher plasma plasminogen activator inhibitor-1 (PAI-1) antigen levels than normal pregnancy. The aim of the present study is to investigate the effect of gestational diabetes on plasma thrombin-activatable fibrinolysis inhibitor (TAFI) antigen levels. Plasma TAFI and PAI-1 antigen levels were measured in 26 pregnant women with gestational diabetes, 25 pregnant women with normal glucose tolerance, and age-matched 24 non-pregnant women with no history of gestational diabetes. Increased plasma TAFI antigen levels were found in pregnant women compared to non-pregnant controls. However, no statistically significant difference in TAFI antigen levels was observed between women with gestational diabetes and pregnant controls. Plasma PAI-1 antigen levels were higher in gestational diabetes than pregnant and non-pregnant controls. Our study revealed that pregnancy was associated with elevated plasma TAFI antigen levels. However, no additional effect of gestational diabetes was found on plasma TAFI antigen levels beyond pregnancy. We suggest that pregnancy is associated with enhanced coagulation and impaired fibrinolysis. Despite increased PAI-1 antigen levels associated with gestational diabetes, the effect of gestational diabetes on TAFI antigen levels is lacking.