The effects of residual platelets in plasma on plasminogen activator inhibitor-1 and plasminogen activator inhibitor-1-related assays

Past, Present, and Future Perspectives of Plasminogen Activator Inhibitor 1 (PAI-1)

Plasminogen activator inhibitor 1 (PAI-1), a SERPIN inhibitor, is primarily known for its regulation of fibrinolysis. However, it is now known that this inhibitor functions and contributes to many (patho)physiological processes including inflammation, wound healing, cell adhesion, and tumor progression.This review discusses the past, present, and future roles of PAI-1, with a particular focus on the discovery of this inhibitor in the 1970s and subsequent characterization in health and disease. Throughout the past few decades diverse functions of this serpin have unraveled and it is now considered an important player in many disease processes. PAI-1 is expressed by numerous cell types, including megakaryocytes and platelets, adipocytes, endothelial cells, hepatocytes, and smooth muscle cells. In the circulation PAI-1 exists in two pools, within plasma itself and in platelet α-granules. Platelet PAI-1 is secreted following activation with retention of the inhibitor on the activated platelet membrane. Furthermore, these anucleate cells contain PAI-1 messenger ribonucleic acid to allow de novo synthesis.Outside of the traditional role of PAI-1 in fibrinolysis, this serpin has also been identified to play important roles in metabolic syndrome, obesity, diabetes, and most recently, acute respiratory distress syndrome, including coronavirus disease 2019 disease. This review highlights the complexity of PAI-1 and the requirement to ascertain a better understanding on how this complex serpin functions in (patho)physiological processes.

Efficacy and Safety of Postoperative Intravenous Tranexamic Acid in Total Knee Arthroplasty: A Prospective Randomized Controlled Study

Objective

To assess the efficacy and safety of postoperative intravenous tranexamic acid (TXA) in patients undergoing total knee arthroplasty (TKA).

Methods

From March 2020 to August 2020, all patients undergoing primary unilateral TKA in our hospital were considered in prospective randomized controlled study. Included patients were randomized into three groups to receive either two doses of 15 mg/kg intravenous TXA postoperatively, at 2 and 24 h after closing the incision (group A), or a single dose of 15 mg/kg intravenous TXA 2 h postoperatively (group B), or placebo (group C). The calculated total blood loss (TBL) and hidden blood loss (HBL), incidence of venous thromboembolism (VTE), and transfusion rate were compared among groups. The levels of prothrombotic state parameters including thrombomodulin (TM), thrombin‐anti‐thrombin complex (TAT), plasmin‐anti‐plasmin complex (PIC), and tissue‐type plasminogen activator‐plasminogen activator inhibitor complex (t‐PAI·C) in plasma were measured during the perioperative period. Patients were compared depending on the Kellgren‐Lawrence classification (K‐L types III and IV).

Results

All patients were followed up for at least 4 weeks. The mean TBL and HBL in group C (1,182.45 ± 160.50; and 965.47 ± 139.61 mL, respectively) were significantly higher than those in groups A (944.34 ± 130.88 mL, P < 0.05; and 712.45 ± 129.82mL, P < 0.05, respectively) or B (995.20 ± 154.00 mL, P < 0.05; and 757.20 ± 134.39 mL, P < 0.05, respectively), but no significant differences were found between groups A and B (P > 0.05 and P > 0.05, respectively). None of the patients of three groups received blood transfusion, so there were no significant differences in blood transfusion rate among groups. Similar results were obtained with subgroups of patients who had the K‐L types III and IV. The DVT frequencies were four, three, and three in groups A, B, and C, respectively, with no significant differences after comparison (P > 0.05). There were no significant differences in the levels of prothrombotic state parameters (TM, TAT, PIC, t‐PAI·C) or incidence of VTE among groups (P > 0.05). Wound leakage was observed in five patients during the hospital stay (two patients in group A, one patient in group B, and two patients in group C), and no statistical difference was found in wound leakage or other complications among groups (P > 0.05).

Conclusions

Short‐term application of postoperative intravenous TXA in TKAs resulted in reduced HBL without a measured increase in the actual incidence of VTE or the potential risk of thrombosis, but administration of TXA after the first 24 h had no significant effect.

Regulatory Mechanism of MicroRNA-30b on Neonatal Hypoxic-Ischemic Encephalopathy (HIE)

OBJECTIVE

This study is to investigate the role of microRNA (miR)-30b in the pathogenesis of hypoxic-ischemic encephalopathy (HIE) in neonates.

METHODS

Totally 26 cases of neonatal HIE were included in this study. The protein expression levels of CD26P and PAI-1 were detected with ELISA. Serum levels of miR-30b and PAI-1 mRNA was measured by quantitative real-time PCR. Human brain microvascular endothelial cells (HBMECs) were cultured under hypoxic condition, and the intracellular expression levels of miR-30b and PAI-1 were evaluated. Dual-luciferase reporter assay was performed to confirm the interaction between miR-30b and PAI-1.

RESULTS

Compared with the control group, both the mRNA and protein expression levels of PAI-1 in the serum were up-regulated in the neonates with HIE, together with up-regulated serum CD26P levels. However, the serum expression level of miR-30b was down-regulated in neonatal HIE. In hypoxia-induced HBMECs, the mRNA and protein expression levels of PAI-1 were significantly up-regulated, while the miR-30b expression level was significantly down-regulated. Dual-luciferase reporter assay showed that PAI-1 was the direct target of miR-30b.

CONCLUSION

Neonatal HIE is accompanied with abnormal platelet activation, significantly up-regulated serum PAI-1 expression levels, and down-regulated miR-30b expression. MiR-30b might regulate the disease pathogenesis and immune responses via modulating PAI-1.

Association of plasminogen activator inhibitor-1 and low-density lipoprotein heterogeneity as a risk factor of atherosclerotic cardiovascular disease with triglyceride metabolic disorder: a pilot cross-sectional study

BACKGROUND

We hypothesized that an increase in plasminogen activator inhibitor 1 (PAI-1) might reduce low-density lipoprotein (LDL) particle size in conjunction with triglyceride (TG) metabolism disorder, resulting in an increased risk of atherosclerotic cardiovascular disease (ASCVD).

METHODS

This study was carried out as a hospital-based cross-sectional study in 537 consecutive outpatients (mean age: 64 years; men: 71%) with one or more risk factors for ASCVD from April 2014 to October 2014 at the Cardiovascular Center of Nihon University Surugadai Hospital. The estimated LDL-particle size was measured as relative LDL migration using polyacrylamide gel electrophoresis with the LipoPhor system.The plasma PAI-1 level, including the tissue PA/PAI-1 complex and the active and latent forms of PAI-1, was determined using a latex photometric immunoassay method.

RESULTS

A multivariate regression analysis after adjustments for ASCVD risk factors showed that an elevated PAI-1 level was an independent predictor of smaller-sized LDL-particle in both the overall patients population (β=0.209, P<0.0001) and a subset of patients with a serum low-density lipoprotein cholesterol (LDL-C) level lower than 100 mg/dl (β=0.276, P<0.0001). Furthermore, an increased BMI and TG-rich lipoprotein related markers [TG, remnant-like particle cholesterol, apolipoprotein (apo) B, apo C-II, and apo C-III] were found to be independent variables associated with an increased PAI-1 level in multivariate regression models. A statistical analysis of data from nondiabetic patients with well-controlled serum LDL-C levels yielded similar findings. Furthermore, in the 310 patients followed up for at least 6 months, a multiple-logistic regression analysis after adjustments for ASCVD risk factors identified the percent changes of the plasma PAI-1 level in the third tertile compared with those in the first tertile as being independently predictive of decreased LDL-particle size [odds ratio (95% confidence interval): 2.11 (1.12/3.40), P=0.02].

CONCLUSION

The plasma PAI-1 levels may be determined by the degree of obesity and TG metabolic disorders. These factors were also shown to be correlated with a decreased LDL-particle size, increasing the risk of ASCVD, even in nondiabetic patients with well-controlled serum LDL-C levels.

MicroRNA-30b protects myocardial cell function in patients with acute myocardial ischemia by targeting plasminogen activator inhibitor-1

The aim of the present study was to determine the expression of plasminogen activator inhibitor-1 (PAI-1) and microRNA (miR)-30b in the blood of patients with acute myocardial ischemia (AMI) and in the blood and myocardial tissue of mice with AMI. In addition, the present study aimed to identify the mechanism of action of miR-30b in AMI. A total of 36 patients with AMI were included in the present study and 28 healthy subjects were included as a control. Peripheral blood was collected from all subjects. For animal experiments, mice in the AMI group received an intraperitoneal injection of pituitrin (20 U/kg), whereas mice in the negative control group received an intraperitoneal injection of the same volume of saline. Blood and myocardial tissue was collected from all mice for analysis. Reverse transcription-quantitative polymerase chain reaction was performed to determine the expression of PAI-1 mRNA and miR-30b in the serum and myocardial tissue. An enzyme-linked immunosorbent assay was performed to measure the expression of PAI-1 protein in the serum of humans and mice, whereas western blotting was performed to determine the expression of PAI-1 protein in mouse myocardial tissue. Catalase, glutathione peroxidase and superoxide dismutase activity was measured using an automatic biochemical analyzer. A dual luciferase assay was performed to identify the interactions between PAI-1 mRNA and miR-30b. The results indicated that patients with AMI have higher PAI-1 levels and lower miR-30b expression in the peripheral blood compared with healthy subjects. AMI damaged the myocardium tissue of mice and reduced catalase, glutathione peroxidase and superoxide dismutase activity. Mice that have undergone AMI exhibit increased PAI-1 levels but decreased miR-30b expression in the peripheral blood and myocardial tissues. It was also demonstrated that miR-30b is able to bind to the 3'-untranslated region of PAI-1 mRNA to regulate its expression. The present study demonstrates that patients with AMI exhibit decreased miR-30b expression and elevated PAI-1 expression in the peripheral blood. miR-30b may therefore inhibit the damage to myocardial cells that occurs following AMI and protect myocardial cell function by targeting PAI-1 expression.