Simvastatin ameliorates deep vein thrombosis in rabbits by regulating the fibrinolytic system

Antiproliferative agent attenuates postthrombotic vein wall remodeling in murine and human subjects

BACKGROUND

Despite appropriate treatment, up to 50% of patients with proximal deep vein thrombosis will develop postthrombotic syndrome (PTS). Once PTS occurs, there is no specific treatment, and some patients constantly experience intolerable symptoms. Hence, prevention of PTS is important.

OBJECTIVES

To characterize vein wall remodeling after thrombus and investigate the effects of antiproliferative agent on postthrombotic vein wall remodeling in murine and human subjects.

METHODS

Features of postthrombotic vein wall remodeling in murine and human subjects were characterized using imaging and histologic examinations. Paclitaxel-loaded hydrogels were used to assess the effects of antiproliferative agent on the remodeling in murine model. Based on the abovementioned results, a pilot study was conducted to assess the effects of paclitaxel-coated balloon dilation in patients with severe PTS experiencing intolerable symptoms. The control cohort was obtained by 1:1 propensity score matching from a prospective database.

RESULTS

Structural and functional alterations in postthrombotic vein wall were verified by imaging and histologic examinations, and predominant active α-smooth muscle actin-positive cells and fibroblast-specific protein 1-positive cells proliferation was observed. In the murine model, the application of paclitaxel-loaded hydrogels inhibited the remodeling. In the pilot clinical study, patients receiving drug-coated balloon demonstrated benefits in Villalta scores and venous clinical severity scores compared with those not receiving drug-coated balloon, and no severe adverse events were reported except for thrombosis recurrence.

CONCLUSION

Cell proliferation plays an important role in postthrombotic vein wall remodeling. Inhibition of cell proliferation inhibits the remodeling in murine model and may reduce signs and symptoms in patients with severe PTS.

Statins during Anticoagulation for Emergency Life-Threatening Venous Thromboembolism: A Review

Venous thromboembolism (VTE) is the leading cause of morbidity and death worldwide, after cancer and cardiovascular diseases. VTE is defined to include pulmonary embolism (PE) and/or deep vein thrombosis (DVT). Approximately 25% of PE patients experience sudden death as an initial symptom of VTE, and between 10% and 30% of patients die within the first month after diagnosis. Currently, the only drugs approved for the treatment of both acute and chronic VTE are vitamin K antagonists (VKAs) and direct oral anticoagulants (DOACs). However, their effectiveness is limited due to their associated risk of bleeding. Ideally, therapy should be able to treat VTE and limit the risk of VTE recurrence without increasing the risk of bleeding. Several studies have shown that the use of statins during anticoagulation for VTE reduces the risk of death and VTE recurrence. However, to date, there are conflicting data on the impact of statins during anticoagulation for VTE. A biological protective function of statins during anticoagulation has also been reported. Statins affect D-dimer levels; tissue factor (TF) gene expression; and VIII, VII, and Von Willebrand clotting factors-the major clotting factors they are able to affect. However, the usefulness of statins for the treatment and prevention of VTE is currently under debate, and they should not be substituted for guideline-recommended VTE prophylaxis or anticoagulation treatment. In this review of the literature, we illustrate the advances on this topic, including data on the role of statins in primary VTE prevention and secondary VTE prevention, related biological mechanisms, the risk of bleeding during their use, and their ability to reduce the risk of death.

Acute Pulmonary Embolism and Immunity in Animal Models

Venous thromboembolism, encompassing acute pulmonary embolism (APE) and deep vein thrombosis (DVT), is a potentially fatal disease with complex pathophysiology. Traditionally, the Virchow triad provided a framework for understanding the pathogenic contributors to thrombus formation, which include endothelial dysfunction, alterations in blood flow and blood hypercoagulability. In the last years, it has become apparent that immunity plays a central role in thrombosis, interacting with classical prothrombotic mechanisms, oxidative stress and vascular factors. Thrombosis amplifies inflammation, and exaggerated inflammatory processes can trigger thrombosis mainly due to the activation of leukocytes, platelets, and endothelial cells. APE-related endothelium injury is a major trigger for immune system activation. Endothelium is also a key component mediating inflammatory reaction and it is relevant to maintain vascular permeability. Exaggerated right ventricular wall stress and overload, with coexisting systemic hypotension and hypoxemia, result in myocardial injury and necrosis. Hypoxia, tissue factor activation and cytokine storm are engaged in the thrombo-inflammatory processes. Thrombus development is characterized by inflammatory state vascular wall caused mainly by an early extravasation of leukocytes and intense selectins and cytokines production. Nevertheless, immunity of DVT is well described, little is known about potential chemokine and cellular differences between thrombus that develops in the vein and thrombus that detaches and lodges in the pulmonary circulation being a cause of APE. There is a paucity of data considering inflammatory state in the pulmonary artery wall during an acute episode of pulmonary embolism. The main aim of this review is to summarize the knowledge of immunity in acute phase of pulmonary embolism in experimental models.

Effect of statins on the risk of recurrent venous thromboembolism: A systematic review and meta-analysis

BACKGROUND

Recent studies have suggested that statins may be associated with a lower risk of recurrent venous thromboembolism (VTE).

METHODS

We systematically searched PubMed, Web of Science and Cochrane Library from inception until May 2020 to identify any eligible studies that reported the association between statin use and the risk of recurrent VTE, and conducted a comprehensive systematic review and meta-analysis (PROSPERO registration number: CRD42020190169) on this matter.

RESULTS

A total of 14 observational studies were included for qualitative review and 12 of them qualified for meta-analyses. The main meta-analysis found that statin use was associated with a lower risk of disease recurrence among patients with VTE (pooled adjusted HR: 0.76, 95% CI: 0.69-0.83), which was robust in sensitivity analyses and free of significant publication bias. Additionally, such association was present when restricting to periods after anticoagulation withdrawal (pooled adjusted HR: 0.78, 95% CI: 0.70-0.88) and when separately analyzing recurrent deep vein thrombosis (pooled adjusted HR: 0.71, 95% CI: 0.62-0.81) and recurrent pulmonary embolism (pooled adjusted HR: 0.80, 95% CI: 0.66-0.97; P = 0.027). Furthermore, statin use in patients with VTE was also found to be associated with a lower risk of all-cause mortality (adjusted HR: 0.65, 95% CI: 0.56-0.77), and possibly an even lower risk of bleeding (adjusted HR: 0.88, 95% CI: 0.73-1.07), albeit not statistically significant.

CONCLUSION

Statins have the potential to reduce recurrent events among patient with VTE. Randomized clinical trials to better explore the effect of statins in secondary prevention of VTE are warranted.

By word of mouse: using animal models in venous thrombosis research

Deep vein thrombosis (DVT) is a disease with high prevalence and morbidity. It can lead to pulmonary embolism with severe respiratory insufficiency and risk of death. Mechanisms behind all stages of DVT, such as thrombosis commencement, propagation, and resolution, remain incompletely understood. Animal models represent an invaluable tool to explore these problems and identify new targets for DVT prevention and treatment. In this review, we discuss existing models of venous thrombosis, their advantages and disadvantages, and applicability to studying different aspects of DVT pathophysiology. We also speculate about requirements for an "ideal model" that would best recapitulate features of human DVT and discuss readouts of various models.

Effect of simvastatin on the SIRT2/NF-κB pathway in rats with acute pulmonary embolism

CONTEXT

Statins have been widely used in acute pulmonary embolism (APE), while simvastatin has been well-established for the prevention of pulmonary hypertension, which was supposed to be an attractive recommendation for APE treatment.

OBJECTIVE

The current article studies the effect of simvastatin on the SIRT2/NF-κB pathway in rats with APE.

MATERIALS AND METHODS

Sprague-Dawley rats were divided into four groups (n = 24 per group): control group, rats were treated with saline once daily for 14 days before administration of saline (sham group) or a suspension of autologous emboli (APE group), or rats were treated with simvastatin (10 mg/kg) for 14 days before administration of autologous emboli (APE + simvastatin) group. The RVSP, mPAP and the arterial blood gas was analyzed. Besides, plasma inflammatory cytokines and MMPs levels, as well as the expression of SIRT2/NF-κB pathway were determined.

RESULTS

Compared with the control and sham groups, the levels of mPAP (31.06 ± 3.47 mmHg), RVSP (35.12 ± 6.02 mmHg), A-aDO₂ (33.14 ± 6.16 mmHg) and MMP-9 (6.89 ± 0.84 ng/mL) activity were significantly elevated, but PaO₂ (66.87 ± 7.85 mmHg) was highly decreased in rats from APE group at 24 h after APE. Meanwhile, the inflammatory changes were aggravated by the enhanced levels of TNF-α (138.85 ± 22.69 pg/mL), IL-1β (128.47 ± 22.14 pg/mL), IL-6 (103.16 ± 13.58 pg/mL) and IL-8 (179.28 ± 25.79 pg/mL), as well as increased NF-κB (5.29 ± 0.47 fold), but reduced SIRT2 (59 ± 6% reduction), and eNOS (61 ± 5% reduction) mRNA in APE rats. APE rats treated with simvastatin led to a significant opposite trend of the above indexes.

CONCLUSIONS

Simvastatin protects against APE-induced pulmonary artery pressure, hypoxemia and inflammatory changes probably due to the regulation of SIRT2/NF-κB signalling pathway, which suggest that simvastatin may have promising protective effects in patients with APE.