Decrease in microvesicle-associated tissue factor activity in morbidly obese patients after bariatric surgery

Current Practices and Guidelines for Perioperative Blood Management in Post-Bariatric Body Contouring Surgery: A Comprehensive Review of Literature

With the increase in obesity prevalence, a noticeable increase in bariatric surgeries has been reported in national and international statistics. Therefore, body contouring surgeries have increased to help individuals achieve their desired body shape. Plastic surgeons need to consider potential hematologic complications that may occur in this specific group of patients before performing body contouring surgery. This review illustrates the perioperative medical, laboratory, and management strategies needed to minimize blood loss and blood transfusion requirements during body contouring. Using Google Scholar and PubMed, a comprehensive literature review was conducted to identify articles discussing post-bariatric body contouring perioperative blood management strategies, including the effects of bariatric surgery on hemostasis as well as basic hematology and coagulation. In preoperative blood management, blood investigations aid in the early detection of electrolytes, protein, and vitamin deficiencies and anemia, resulting in the early correction of nutritional deficiencies. In order to reduce postoperative complications, surgical and anesthesia techniques, as well as intraoperative pharmacological therapy, play an essential role. Postoperative blood transfusion and restrictive transfusion thresholds are tailored to the patient's needs and depend on various physiological indicators, such as heart rate, blood pressure, urine output, and laboratory findings, such as acidosis and hematocrit level. Generally, post-bariatric body contouring blood management measures are still lacking, and more research is required to develop standardized guidelines for optimizing patient safety and satisfaction.Level of Evidence III This journal requires that authors assign a level of evidence to each article. For a full description of these Evidence-Based Medicine ratings, please refer to the Table of Contents or the online Instructions to Authors www.springer.com/00266 .

Circulating tissue factor-positive extracellular vesicles and their association with thrombosis in different diseases

Tissue factor (TF) is a procoagulant protein released from activated host cells, such as monocytes, and tumor cells on extracellular vesicles (EVs). TF + EVs are observed in the circulation of patients with various types of diseases. In this review, we will summarize the association between TF + EVs and activation of coagulation and survival in different types of diseases, including cancer, sepsis, and infections with different viruses, such as human immunodeficiency virus (HIV), influenza A virus (IAV), and severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2). We will also discuss the source of TF + EVs in various diseases. EVTF activity is associated with thrombosis in pancreatic cancer patients and coronavirus disease 2019 patients (COVID-19) and with disseminated intravascular coagulation in cancer patients. EVTF activity is also associated with worse survival in patients with cancer and COVID-19. Monocytes are the major sources of TF + EVs in sepsis, and viral infections, such as HIV, Ebola virus, and SARS-CoV-2. In contrast, alveolar epithelial cells are the major source of TF + EVs in bronchoalveolar lavage fluid in COVID-19 and influenza A patients. These studies indicate that EVTF activity could be used as a biomarker to identify patients that have an increased risk of coagulopathy and mortality.

Revised model of the tissue factor pathway of thrombin generation: Role of the feedback activation of FXI

BACKGROUND

Biochemical reaction networks are self-regulated in part due to feedback activation mechanisms. The tissue factor (TF) pathway of blood coagulation is a complex reaction network controlled by multiple feedback loops that coalesce around the serine protease thrombin.

OBJECTIVES

Our goal was to evaluate the relative contribution of the feedback activation of coagulation factor XI (FXI) in TF-mediated thrombin generation using a comprehensive systems-based analysis.

MATERIALS AND METHODS

We developed a systems biology model that improves the existing Hockin-Mann (HM) model through an integrative approach of mathematical modeling and in vitro experiments. Thrombin generation measured using in vitro assays revealed that the feedback activation of FXI contributes to the propagation of thrombin generation based on the initial concentrations of TF or activated coagulation factor X (FXa). We utilized experimental data to improve the robustness of the HM model to capture thrombin generation kinetics without a role for FXI before including the feedback activation of FXI by thrombin to construct the extended (ext.) HM model.

RESULTS AND CONCLUSIONS

Using the ext.HM model, we predicted that the contribution of positive feedback of FXI activation by thrombin can be abolished by selectively eliminating the inhibitory function of tissue factor pathway inhibitor (TFPI), a serine protease inhibitor of FXa and TF-activated factor VII (FVIIa) complex. This prediction from the ext.HM model was experimentally validated using thrombin generation assays with function blocking antibodies against TFPI and plasmas depleted of FXI. Together, our results demonstrate the applications of combining experimental and modeling techniques in predicting complex biochemical reaction systems.

Prior bariatric surgery in COVID-19-positive patients may be protective

Background

Patients infected with novel COVID-19 virus have a spectrum of illnesses ranging from asymptomatic to death. Data have shown that age, sex, and obesity are strongly correlated with poor outcomes in COVID-19–positive patients. Bariatric surgery is the only treatment that provides significant, sustained weight loss in the severely obese.

Objectives

Examine if prior bariatric surgery correlates with increased risk of hospitalization and outcome severity after COVID-19 infection.

Setting

University hospital

Methods

A cross-sectional retrospective analysis of a COVID-19 database from a single, New York City–based, academic institution was conducted. A cohort of COVID-19–positive patients with a history of bariatric surgery (n = 124) were matched in a 1:4 ratio to a control cohort of COVID-19–positive patients who were eligible for bariatric surgery (BMI ≥40 kg/m² or BMI >35 kg/m² with a co-morbidity at the time of COVID-19 diagnosis) (n = 496). A comparison of outcomes, including mechanical ventilation requirements and deceased at discharge, was done between cohorts using χ² test or Fisher’s exact test. Additionally, overall length of stay and duration of time in intensive care unit (ICU) were compared using Wilcoxon rank sum test. Conditional logistic regression analyses were done to determine both unadjusted (UOR) and adjusted odds ratios (AOR).

Results

A total of 620 COVID-19–positive patients were included in this analysis. The categorization of bariatric surgeries included 36% Roux-en-Y gastric bypass (RYGB, n = 45), 36% laparoscopic adjustable gastric banding (LAGB, n = 44), and 28% laparoscopic sleeve gastrectomy (LSG, n = 35). The body mass index (BMI) for the bariatric group was 36.1 kg/m² (SD = 8.3), which was significantly lower than the control group, 41.4 kg/m² (SD = 6.5, P < .0001). There was also less burden of diabetes in the bariatric group (32%) compared with the control group (48%) (P = .0019). Patients with a history of bariatric surgery were less likely to be admitted through the emergency room (UOR = .39, P = .0001), less likely to require a ventilator during the admission (UOR=.42, P = .028), had a shorter length of stay in both the ICU (P = .033) and overall (UOR = .44, P = .0002), and were less likely to be deceased at discharge compared with the control group (OR = .42, P = .028).

Conclusion

A history of bariatric surgery significantly decreases the risk of emergency room admission, mechanical ventilation, prolonged ICU stay, and death in patients with COVID-19. Even when adjusted for BMI and the co-morbidities associated with obesity, patients with a history of bariatric surgery still have a significant decrease in the risk of emergency room admission.

The role of bariatric surgery in normalization of the coagulation profiles

BACKGROUND

Bariatric surgery achieves appropriate excess weight loss, controlling related co-morbidities, including coagulation abnormalities.

OBJECTIVE

We investigated the change in the coagulation profile after postoperative weight stabilization, correlating between EWL ratio and change in the coagulation profile.

SETTING

This study took place in our teaching institution (university setting).

METHODS

Between the years 2012 and 2014, 67 patients underwent surgery; 47 patients underwent laparoscopic sleeve gastrectomy (SG) and 20 patients underwent Roux-en-Y gastric bypass (RYGB). Average follow-up of postoperative thromboelastography (TEG) parameters was 30 ± 10.8 months (12-77). Average body mass index (BMI) before surgery was 41.7 ± 4.6kg/m², average percentage of EWL at the time of data collection was 79%. Patients were divided into 3 groups, 6 patients had EWL < 50%, 13 had an EWL > 100%, and 48 had EWL between 50% and 100%.

EXCLUSION CRITERIA

use of anticoagulation, antiplatelet, or contraceptive medications; known thrombophilic, renal, hepatic, and hematologic diseases/disorders. Two follow-up groups: 1-2 years and over 2 years. Patients underwent pre and postoperative TEG coagulation studies, including maximal amplitude (MA), and clot strength (G).

RESULTS

Coagulation profile improved after bariatric surgery. Most prominent change seen in MA and G. There was a linear correlation between the EWL ratio and improvement of MA values starting at 50% EWL peaking at 60%-70%. There was no difference in the coagulation profile after surgery in the two surgery groups (SG and RYGB).

CONCLUSIONS

Achieving appropriate weight loss after bariatric surgery improves the coagulation profile as measured by TEG, probably decreasing thromboembolic risk in those patients. We recommend expanding the current indication for bariatric surgery to include patients with altered coagulation profile measured by TEG.

Mesenchymal stem cell-derived microvesicles mediate BMP2 gene delivery and enhance bone regeneration

Microvesicles–polyethyleneimine/pDNA formed via layer-by-layer self-assembly increase the delivery of hBMP2 plasmids and enhance bone repair.

Bariatric surgery in morbidly obese individuals affects plasma levels of protein C and thrombomodulin

Obesity is associated with a prothrombotic milieu and an increased risk for thrombotic events. Bariatric surgery is the most effective treatment for obesity resulting in dramatic weight loss and reduced inflammation and extrinsic coagulation pathway activation. Blood samples were drawn from 60 patients undergoing Roux-en-Y gastric bypass surgery before and 1 year after the intervention. Protein C (PC), activated PC (APC), soluble thrombomodulin (TM), soluble E-selectin (E-Sel), prothrombin time (PT) and activated partial thromboplastin time (aPTT) were evaluated. Both PC (187.4 ± 64.5% before surgery to 118.1 ± 48% 1 year after surgery, p < 0.001) and APC (138.7 ± 64.4% before surgery to 69.1 ± 65.7% after surgery, p < 0.001) were reduced following surgical intervention. TM showed a similar behavior with a reduction of soluble TM after the procedure from 5.7 ± 2.6 to 3.2 ± 1.4 ng/ml (p < 0.001). Similarly, soluble E-Sel was reduced after surgery from 26.6 ± 12.7 to 5.5 ± 4.1 ng/ml (p < 0.001). In contrast, aPTT was not shortened but slightly increased from 29.1 ± 4.8 s. before surgery to 31 ± 4.4 s. (p = 0.001) after surgery and levels of PT were reduced after surgery to 89.6 ± 15.5% from an initial 97.5 ± 13.5% (p < 0.001). In conclusion, we demonstrate a reduction of PC and APC 1 year after bariatric surgery accompanied by a reduction in soluble TM and soluble E-Sel. The reduction of PC and APC is not paralleled by a reduction but in contrast by a prolongation of aPTT suggesting a compensatory upregulation of PC during obesity. The reduction of TM and E-Sel might hint towards an improved endothelial function in this cohort of patients.

Pathogenic roles of microvesicles in diabetic retinopathy

Diabetic retinopathy (DR) is a common complication of diabetes and has been recognized as the leading cause of blindness in adults. Several interrelated molecular pathways are involved in the development of DR. Microvesicles (MVs) are cell membrane vesicles, which carry many biologic molecules, such as mRNAs, microRNAs, transcription factors, membrane lipids, membrane receptors, and other proteins. They may be involved in intercellular communication that can promote inflammation, angiogenesis, and coagulation. Recent studies have indicated that changes in the number and composition of MVs may reflect the pathologic conditions of DR. At present, MVs are well recognized as being involved in the pathophysiological conditions of tumors and cardio-metabolic diseases. However, the roles of MVs in DR have yet to be investigated. In this review, we provide an overview of DR-induced microvascular injury that is caused by MVs derived from endothelial and circulating cells, and discuss the possible mechanisms by which MVs can lead to endothelial dysfunction, coagulation and inflammation. In addition, the protective effects of preconditioned MVs and stem cell-derived MVs are also described . Understanding the involvement of MVs in the pathophysiological conditions of DR may provide insight into the disease mechanisms and may suggest novel therapeutic strategies for DR in the future.

Body Weight Reduction and Biochemical Parameters of the Patients After RYGB and SG Bariatric Procedures in 12-Month Observation

Background

The aim of this study was to evaluate the effect of sleeve gastrectomy (SG) and Roux-en-Y-bypass (RYGB) on anthropometric and biochemical parameters, including changes in glucose levels, lipid profile and liver function. Drastic decrease in all lipid fractions a few weeks or months after the surgery could be regarded as favourable, but low level of HDL is an independent risk factor for heart diseases. Extreme load on the liver without preparation of the patient to the surgery can have negative consequences.

Methods

The test group comprised of 40 female patients at the age of 42.96 with average body weight of 131.56 kg and BMI 46.49. Biochemical analyses were performed using calorimetric method.

Results

No statistically significant differences were observed in glucose levels between the two types of procedures. The highest differences were noted for triglycerides levels, which decreased, as well as all cholesterol fractions, after RYGB, but were increasing during the first months after SG procedure. Changes in lipid profile, caused by the reduction of all lipid fractions, were more visible after RYGB. The decrease in total cholesterol directly and activity of liver enzymes after the procedure was as higher after RYGB as after SG. Increased activity of transaminases indicates significant liver overload.

Conclusions

With the selection of groups of patients with similar initial parameters, it is not clear whether the differences between the two procedures when assessing the improvement of glycaemia are significant. However, due to invasive character of RYGB, liver overload lasting several months and lifelong limited absorption of nutrients, the possibility of SG procedure should be considered as a first option.

Risk of venous thrombosis in persons with increased body mass index and interactions with other genetic and acquired risk factors

Essentials Obesity, factor V Leiden (FVL) and blood group non-O are common. We studied the combined effect of these factors on the risk of venous thrombosis (VT). The combination of obesity, non-O blood group and FVL increased VT risk up to ten-fold. Identifying high VT may be beneficial in thrombosis prevention.

SUMMARY

Background Overweight/obesity has a substantial effect on the occurrence of venous thrombosis (VT). Blood group non-O has a high prevalence in Western populations, and the factor V Leiden mutation could be present in 5% of Caucasians. These frequent prothrombotic risk factors will have a considerable impact on the incidence of VT, especially when combined. Objectives We investigated whether FV Leiden with blood group non-O modifies VT risk in individuals with different body mass index (BMI) strata in a case-control study (n = 11253). Results We observed a progressively increasing risk of VT with higher BMI, with an odds ratio of 1.9 (95% confidence interval [CI] 1.6-2.3) for those in the upper BMI tertile (BMI > 26.7 kg m(-2) ), as compared with the first BMI tertile (BMI < 23.5 kg m(-2) , blood group O, and no FV Leiden) (reference group). The addition of FV Leiden and blood group non-O to the model increased the risk in all BMI tertiles; the odds ratios were 3.8 (95% CI 3.2-4.6) in the third BMI tertile of individuals with blood group non-O, and 5.4 (95% CI 3.5-8.5) in the third BMI tertile of individuals with FV Leiden. When both FV Leiden and blood group non-O were present, the odds ratios were 9.1 (95% CI 5.9-14.0) in the first BMI tertile, 9.4 (95% CI 6.6-13.5) in the second BMI tertile, and 12.5 (95% CI 8.9-17.6) in the third BMI tertile. Conclusion Individuals with a high BMI, blood group non-O and/or FV Leiden have a high VT risk. The high VT risks in some subgroups may justify targeted screening and thromboprophylaxis decisions in these patients.

Measurement of microparticle tissue factor activity in clinical samples: A summary of two tissue factor-dependent FXa generation assays

Thrombosis is a leading cause of morbidity and mortality. Detection of a prothrombotic state using biomarkers would be of great benefit to identify patients at risk of thrombosis that would benefit from thromboprophylaxis. Tissue factor (TF) is a highly procoagulant protein that under normal conditions is not present in the blood. However, increased levels of TF in the blood in the form of microparticles (MPs) (also called extracellular vesicles) are observed under various pathological conditions. In this review, we will discuss studies that have measured MP-TF activity in a variety of diseases using two similar FXa generation assay. One of the most robust signals for MP-TF activity (16-26 fold higher than healthy controls) is observed in pancreatic cancer patients with venous thromboembolism. In this case, the TF+ MPs appear to be derived from the cancer cells. Surprisingly, cirrhosis and acute liver injury are associated with 17-fold and 38-fold increases in MP-TF activity, respectively. Based on mouse models, we speculate that the TF+ MPs are derived from hepatocytes. More modest increases are observed in patients with urinary tract infections (6-fold) and in a human endotoxemia model (9-fold) where monocytes are the likely source of the TF+ MPs. Finally, there is no increase in MP-TF activity in the majority of cardiovascular disease patients. These studies indicate that MP-TF activity may be a useful biomarker to identify patients with particular diseases that have an increased risk of thrombosis.