Unraveling pleiotropic effects of statins: bit by bit, a slow case with perspective

Statins and risk of venous thromboembolic diseases: A two-sample mendelian randomization study

BACKGROUND AND AIMS

In observational studies, statins have been suggested to have protective effects on venous thromboembolism (VTE), including deep vein thrombosis (DVT) and pulmonary embolism (PE). To this aim, we performed a two-sample mendelian randomization (MR) analysis to determine whether these associations were causal.

METHODS AND RESULTS

Data on the single nucleotide polymorphisms (SNPs) related to statin medication were obtained from the FinnGen study, and data for VTE, PE and DVT of lower extremities (LEDVT) were from the UK Biobank study, respectively. Inverse variance weighted (IVW) method was used as the principal analysis of MR, and sensitivity analysis was performed to detect horizontal pleiotropy and heterogeneity. MR estimates showed an inverse causal association between statin medication and the risk of VTE (odds ratio [OR]: 0.999, 95% CI: 0.998-1.000, P = 0.004), PE (OR: 0.999, 95% CI: 0.999-1.000, P = 0.011) and LEDVT (OR: 0.999, 95% CI: 0.999-1.000, P = 0.008).

CONCLUSION

Our findings provide direct evidence that statins might decrease the risk of VTE, PE and LEDVT in agreement with observational studies. The specific mechanism of statin therapy for venous thromboembolism needs to be further studied.

Statin use and 30-day mortality in patients with acute symptomatic pulmonary embolism

BACKGROUND

Statins possess antithrombotic and profibrinolytic properties. The association between statin use and short-term outcomes in patients with acute pulmonary embolism (PE) remains unknown.

METHODS

We used the data from the Registro Informatizado de Pacientes con Enfermedad TromboEmbólica registry to compare the 30-day all-cause mortality in patients with acute PE according to the use of statins. Secondary outcome was fatal PE. We used cancer-related mortality as a falsification endpoint.

RESULTS

From January 2009 to April 2021, 31 169 patients with PE were recruited. Of these, 5520 (18%) were using statins at baseline: low intensity: 829, moderate: 3636, high intensity: 1055. Statin users were older and had a higher frequency of diabetes, hypertension, or atherosclerotic disease than non-users (P <0.001 for all comparisons). During the first 30 days, 1475 patients died (fatal PE, 255). On multivariable analysis, statin users had a lower risk of all-cause death (odds ratio [OR]: 0.65; 95% confidence interval [CI]: 0.56-0.76) and fatal PE (OR: 0.42; 95% CI: 0.28-0.62) than non-users. The risk for death was lower in patients using either low- (OR: 0.51; 95% CI: 0.34-0.77), moderate- (OR: 0.68; 95% CI: 0.57-0.81), or high-intensity statins (OR: 0.68; 95% CI: 0.51-0.92). Results did not change in mixed effects logistic regression models with hospitals as a random effect. Statins were not associated with a significant chance in cancer mortality (falsification endpoint).

CONCLUSIONS

PE patients using statins at baseline had a significantly lower risk of dying within the first 30 days than non-users. Randomized trials are needed to confirm these data.

The Association Between the Use of Statins and Clinical Outcomes in Patients with COVID-19: A Systematic Review and Meta-analysis

Purpose

Previously, we have reported potential clinical benefits with the use of statins in patients with coronavirus disease 2019 (COVID-19) in a meta-analysis, where there was a significantly reduced hazard for a fatal or severe course of illness with the use of statins, but the meta-analysis was limited by the small number of studies included, with small heterogeneity among studies, due to the unavailability of more studies at the point of literature search. We aimed to perform an updated systematic review and meta-analysis to summarize the existing evidence on the effect of statins on the clinical outcomes of patients with COVID-19.

Methods

Electronic databases, including PubMed, Google Scholar, and Scopus, and preprint servers were searched (last updated June 3, 2021) to identify studies investigating the association between the use of statins in patients with COVID-19 and the development of severe disease and/or mortality. Random-effects model meta-analyses were performed to estimate the pooled odds ratio (OR) or hazard ratio (HR) with 95% confidence intervals (CIs). The outcomes of interest were (1) all-cause mortality and (2) a composite endpoint of severe illness of COVID-19.

Results

Upon systematic literature search, we identified 35 studies, of which 32 studies reported the outcome of all-cause mortality and 15 studies reported the composite endpoint of severe COVID-19 illness between statin users versus non-statin users with COVID-19. Our meta-analysis revealed that the use of statins was associated with a significantly lower risks of all-cause mortality (HR = 0.70, 95% CI 0.58–0.84, n = 21,127, and OR = 0.63, 95% CI 0.51–0.79, n = 115,097) and the composite endpoint of severe illness (OR = 0.80, 95% CI 0.73–0.88, n = 10,081) in patients with COVID-19, compared to non-use of statins, at the current sample size.

Conclusion

Statin use is associated with a better prognosis in patients with COVID-19. Our findings provide a rationale to investigate the use of statins among patients with COVID-19 in large scale clinical trials.

Association of statin use and the risk of recurrent pulmonary embolism in real-world Chinese population

Background

Previous studies have suggested that statins exert protective effects against venous thromboembolism. However, few randomized studies have explicitly concentrated on patients with pulmonary embolism. Thus far, evidence of the effect of statins on the pulmonary embolism recurrence in China remains lacking.

Methods

A retrospective analysis was conducted utilizing our University database. Patients with an International Coding of Diseases-defined diagnosis of pulmonary embolism from 1 January 2017 to 31 December 2019 were included. The patients were divided into two groups, namely, with statin or without statin treatment. Propensity score matching was applied to balance the covariates between the comparison groups. Univariate analysis and multivariable logistic regression were performed to analyze the association between statin use and pulmonary embolism recurrence.

Results

A total of 365 patients diagnosed with pulmonary embolism were included in the research. Pulmonary embolism recurrence accounted for 15.1% of the patients and was observed during the entire study period. In the initial population, no significant difference in recurrence was observed between the groups with and without statins treatment (statin 15.6% vs. non-statin 14.9%, p = 0.860). After propensity score matching, multivariate logistic regression analysis revealed that the odds ratio of pulmonary embolism recurrence in the statin users was 0.489 (95% confidence interval 0.190–1.258, p = 0.138).

Conclusions

Our study provides no support for the use of statins as an adjunctive therapy in patients with pulmonary embolism at the initiated time of diagnosis or as a prophylactical plan when anticoagulation is discontinued attempting to reduce the risk of recurrence.

Perspective Adjunctive Therapies for COVID-19: Beyond Antiviral Therapy

The coronavirus disease 2019 (COVID-19) pandemic is the largest health crisis ever faced worldwide. It has resulted in great health and economic costs because no effective treatment is currently available. Since infected persons vary in presentation from healthy asymptomatic mild symptoms to those who need intensive care support and eventually succumb to the disease, this illness is considered to depend primarily on individual immunity. Demographic distribution and disease severity in several regions of the world vary; therefore, it is believed that natural inherent immunity provided through dietary sources and traditional medicines could play an important role in infection prevention and disease progression. People can boost their immunity to prevent them from infection after COVID-19 exposure and can reduce their inflammatory reactions to protect their organ deterioration in case suffering from the disease. Some drugs with in-situ immunomodulatory and anti-inflammatory activity are also identified as adjunctive therapy in the COVID-19 era. This review discusses the importance of COVID-19 interactions with immune cells and inflammatory cells; and further emphasizes the possible pathways related with traditional herbs, medications and nutritional products. We believe that such pathophysiological pathway approach treatment is rational and important for future development of new therapeutic agents for prevention or cure of COVID-19 infection.

Therapeutic implications of statins in heart failure with reduced ejection fraction and heart failure with preserved ejection fraction: a review of current literature

Statins are one of the standard treatments to prevent cardiovascular events such as coronary artery disease and heart failure (HF). However, data on the use of statins to improve clinical outcomes in patients with established HF remains controversial. We summarized available clinical studies which investigated the effects of statins on clinical outcomes in patients with HF with reduced ejection fraction (HFrEF) and HF with preserved ejection fraction (HFpEF). Statins possess many pleiotropic effects in addition to lipid-lowering properties that positively affect the pathophysiology of HF. In HFrEF, data from two large randomized placebo-controlled trials did not show benefits of statins on mortality of patients with HFrEF. However, more recent prospective cohort studies and meta-analyses have shown decreased risk of mortality as well as cardiovascular hospitalization with statins treatment. In HFpEF, most prospective and retrospective cohort studies as well as meta analyses have consistently reported positive effects of statins, including reducing mortality and improving other clinical outcomes. Current evidence also suggests better outcomes with lipophilic statins in patients with HF. In summary, statins might be effective in improving survival and other clinical outcomes in patients with HF, especially for patients with HFpEF. Lipophilic statins might also be more beneficial for HF patients. Based on current evidence, statins did not cause harm and should be continued in HF patients who are already taking the medication. Further randomized controlled trials are needed to clarify the benefits of statins in HF patients.

Statin Use is Associated with Reduced Risk of Recurrence in Patients with Venous Thromboembolism

BACKGROUND

Statin therapy appears to reduce incidence of venous thromboembolism in secondary analyses of non-venous thromboembolism trials, but no evidence has shown effect of statins in large population samples. The objective of this study was to examine the magnitude of the effect of statin therapy on venous thromboembolism recurrence across a large statewide population.

METHODS

This was a retrospective analysis of the Indiana Network for Patient Care database. All patients with an International Classification of Diseases-defined diagnosis of either deep vein thrombosis or pulmonary embolism from 2004-2017 were included. We collected Generic Product Identifier codes to determine whether patients had been prescribed a statin medication and divided patients into 2 groups: + or - statin. We then performed a propensity-matching analysis to balance covariates and created a final logistic regression model with statin use as the predictor variable and venous thromboembolism recurrence as the dependent variable.

RESULTS

This study included a total of 192,908 patients with documented statin use in 13.5%. Venous thromboembolism recurrence occurred in 16% of all patients over the study period. After propensity matching, patients not on a statin were found to have significantly higher rates of venous thromboembolism recurrence (20% vs 16%, P < .0001). Logistic regression yielded an odds ratio of 0.75 (95% confidence interval, 0.72-0.79) for venous thromboembolism recurrence for those on statin therapy.

CONCLUSIONS

We found that a statin prescription reduced risk of venous thromboembolism recurrence by approximately 25% after adjusting for risk factors, supporting the adjunctive role of statins in the prevention of venous thromboembolism recurrence.

Potential role of statins in COVID-19

Patients with COVID-19 infection have an increased risk of cardiovascular complications and thrombotic events. Statins are known for their pleiotropic anti-inflammatory, antithrombotic and immunomodulatory effects. They may have a potential role as adjunctive therapy to mitigate endothelial dysfunction and dysregulated inflammation in patients with COVID-19 infection.

Statin therapy and recurrent venous thromboembolism in the elderly: a prospective cohort study

Previous studies reported lower rates of recurrent venous thromboembolism (rVTE) among statin users, but this association could be influenced by concurrent anticoagulation and confounding by statin indication. This study aimed to confirm the beneficial association between statins and rVTE, stratified according to periods with and without anticoagulation, and additionally employ propensity score weighted approach to reduce risk of confounding by indication. The setting was a prospective multicentre cohort study and the outcome was time to first rVTE in statin vs. non-statin users. 980 participants with acute VTE were enrolled (mean age 75.0 years, 47% women), with median follow-up of 2.5 years. Of 241 (24.3%) statin users, 21 (8.7%) suffered rVTE vs. 99 (13.4%) among 739 non-users. The overall adjusted sub-hazard ratio (aSHR) for rVTE comparing statin users to non-users was 0.72 (95%CI 0.44 to 1.19, p = 0.20). This association was only apparent during periods without anticoagulation (aSHR 0.50, 95%CI 0.27 to 0.92, p = 0.03; vs. with anticoagulation: aSHR 1.34, 95%CI 0.54 to 3.35, p = 0.53). Using propensity scores, the rVTE risk during periods without anticoagulation fell further (aSHR 0.20, 95%CI 0.08 to 0.49, p < 0.001). In conclusion, statin use is associated with a more pronounced risk reduction for rVTE than previously estimated, but only during periods without anticoagulation.

Usefulness of Statins for Prevention of Venous Thromboembolism

Venous thromboembolism (VTE), including deep venous thrombosis and pulmonary embolism, is common with an annual incidence of 1 to 5 per 1,000, resulting in major morbidity, mortality, and increased health care costs. It is more common in the elderly, obese, those with cancer, those undergoing surgery, and those with previous VTE. Strategy to reduce its occurrence has important public health implications. Pleotropic effects of statins may have beneficial effects on a number of potential targets associated with VTE. Statins have excellent safety profile and seem to be associated with beneficial effects in VTE in case-control studies, large observational studies, meta-analyses, and a randomized trial. In conclusion, after critically reviewing the clinical data supporting statin use in the prevention of VTE, we presented clinical recommendations for the use of statins in reducing VTE occurrence, especially in high-risk situations.

Simvastatin Suppresses Interleukin Iβ Release in Human Peripheral Blood Mononuclear Cells Stimulated With Cholesterol Crystals

Statins are mainstream therapy in the treatment and prevention of cardiovascular disease through inhibitory effects on cholesterol synthesis. However, statins' beneficial effects in cardiovascular disease may also be attributable to their role as anti-inflammatory mediators. Here, we investigated the effects of simvastatin treatment on expression levels of interleukin (IL) 1β in both patient with hyperlipidemia and healthy human peripheral blood mononuclear cells (PBMCs) using cholesterol crystals (CC), a cardiovascular pathogenic stimulus for activation of the NOD-like receptor pyrin domain-containing protein 3 (NLRP3) inflammasome. Cholesterol crystal-induced NLRP3 inflammasome activation was used to trigger maturation and release of IL-1β in PBMCs. Specifically, isolated PBMCs from patients with hyperlipidemia at baseline and following 8 weeks of in vivo treatment with simvastatin (10-20 mg) daily were stimulated with lipopolysaccharide (LPS; 100 ng/mL) for 3 hours to induce proIL-Iβ expression followed by CC (2 mg/mL) stimulation for further 18 hours to activate the NLRP3 inflammasome complex to induce maturation/activation of IL-1β. Peripheral blood mononuclear cells were also isolated from healthy donors and stimulated in vitro with simvastatin (50, 25, 5, and 2 µmol/L) prior to stimulation with LPS and CC as described above. The effects of simvastatin treatment on levels of IL-1β expression were determined by enzyme-linked immunosorbent assay and western blot. Both in vitro and in vivo treatments with simvastatin led to a significant reduction in the levels of expression of IL-1β in response to stimulation with CC. Simvastatin inhibits the expression and activation of IL-1β induced by CC in PBMCs, which may contribute to its protective role in patients with cardiovascular disease.

Statins as a preventative therapy for venous thromboembolism

The anti-inflammatory effects of statins have likely not been used to their fullest extent, particularly in reducing venous thromboembolic events. Current therapy for thrombotic events hinges on anticoagulation via heparin, warfarin or new oral anticoagulants. Interventional procedures with thrombectomy may also play a critical role. Unfortunately, thrombotic events can occur and recur despite meticulous anticoagulation therapy. Venous thromboembolism (VTE) includes both deep vein thrombosis (DVT) and pulmonary embolism (PE), two complicated and prevalent diseases that can cause chronic disease states such as post-thrombotic syndrome (PTS). In 2009 the JUPITER trial demonstrated that rosuvastatin may be effective when dealing with vascular inflammation by providing an anti-inflammatory effect. Multiple subsequent studies have looked at this association with some promising findings. The mechanism of action for statins is not entirely understood but there has been a variety of proposals and subsequent testing of inflammatory biomarkers. Additional prospective trials are needed to confirm the possible benefit of VTE reduction through an anti-inflammatory effect, but if this can be shown then statins may become a safe adjunctive therapy for VTE prevention.

Statins Promote Cardiac Infarct Healing by Modulating Endothelial Barrier Function Revealed by Contrast-Enhanced Magnetic Resonance Imaging

OBJECTIVE

The endothelium has a crucial role in wound healing, acting as a barrier to control transit of leukocytes. Endothelial barrier function is impaired in atherosclerosis preceding myocardial infarction (MI). Besides lowering lipids, statins modulate endothelial function. Here, we noninvasively tested whether statins affect permeability at the inflammatory (day 3) and the reparative (day 7) phase of infarct healing post-MI using contrast-enhanced cardiac magnetic resonance imaging (MRI).

APPROACH AND RESULTS

Noninvasive permeability mapping by MRI after MI in C57BL/6, atherosclerotic ApoE^-/-, and statin-treated ApoE^-/- mice was correlated to subsequent left ventricular outcome by structural and functional cardiac MRI. Ex vivo histology, flow cytometry, and quantitative polymerase chain reaction were performed on infarct regions. Increased vascular permeability at ApoE^-/- infarcts was observed compared with C57BL/6 infarcts, predicting enhanced left ventricular dilation at day 21 post-MI by MRI volumetry. Statin treatment improved vascular barrier function at ApoE^-/- infarcts, indicated by reduced permeability. The infarcted tissue of ApoE^-/- mice 3 days post-MI displayed an unbalanced Vegfa(vascular endothelial growth factor A)/Angpt1 (angiopoetin-1) expression ratio (explaining leakage-prone vessels), associated with higher amounts of CD45⁺ leukocytes and inflammatory LY6C^hi monocytes. Statins reversed the unbalanced Vegfa/Angpt1 expression, normalizing endothelial barrier function at the infarct and blocking the augmented recruitment of inflammatory leukocytes in statin-treated ApoE^-/- mice.

CONCLUSIONS

Statins lowered permeability and reduced the transit of unfavorable inflammatory leukocytes into the infarcted tissue, consequently improving left ventricular outcome.

Statins and secondary prevention of venous thromboembolism: pooled analysis of published observational cohort studies

AIMS

There have been suggestions that statins may have a potential role in secondary prevention of venous thromboembolism (VTE) [which includes deep vein thrombosis (DVT) and pulmonary embolism (PE)], but the evidence is inconsistent. We aimed to evaluate the association between statin use and risk of recurrent VTE.

METHODS AND RESULTS

We conducted a systematic review and meta-analysis of observational cohort studies. All relevant studies which reported associations between statin use and recurrent VTE outcomes were identified from MEDLINE, EMBASE, Web of Science, and manual search of bibliographies from inception to January 2017. Study specific relative risks (RRs) with 95% confidence intervals were aggregated using random effects models. Eight eligible studies comprising of 103 576 participants and 13 168 recurrent VTE outcomes were included in the pooled analysis. In pooled analysis of 7 studies, the RR for recurrent VTE was 0.73 (0.68-0.79) when comparing statin use with no use. There was no evidence of heterogeneity between contributing studies (I2=0%, 0-71%; P = 0.93). The RRs for recurrent PE (three studies) and DVT (two studies) comparing statin use with no statin use were 0.75 (95% CI: 0.58-0.96) and 0.66 (95% CI: 0.60-0.71) respectively.

CONCLUSION

Available evidence from observational cohort studies suggests a beneficial effect of statin use on VTE recurrence. Well-designed intervention studies are needed to corroborate these findings.

Antithrombotic Effects of Nur77 and Nor1 Are Mediated Through Upregulating Thrombomodulin Expression in Endothelial Cells

OBJECTIVE

Thrombomodulin is highly expressed on the lumenal surface of vascular endothelial cells (ECs) and possesses potent anticoagulant, antifibrinolytic, and anti-inflammatory activities in the vessel wall. However, the regulation of thrombomodulin expression in ECs remains largely unknown.

APPROACHES AND RESULTS

In this study, we characterized nuclear receptor 4A family as a novel regulator of thrombomodulin expression in vascular ECs. We demonstrated that both nuclear receptors 4A, Nur77 and Nor1, robustly increase thrombomodulin mRNA and protein levels in human vascular ECs and in mouse liver tissues after adenovirus-mediated transduction of Nur77 and Nor1 cDNAs. Moreover, Nur77 deficiency and knockdown of Nur77 and Nor1 expression markedly attenuated the basal and vascular endothelial growth factor165-stimulated thrombomodulin expression. Mechanistically, we found that Nur77 and Nor1 increase thrombomodulin expression by acting through 2 different mechanisms. We showed that Nur77 barely affects thrombomodulin promoter activity, but significantly increases thrombomodulin mRNA stability, whereas Nor1 enhances thrombomodulin expression mainly through induction of Kruppel-like factors 2 and 4 in vascular ECs. Furthermore, we demonstrated that both Nur77 and Nor1 significantly increase protein C activity and inhibit tumor necrosis factor α-induced prothrombotic effects in human ECs. Deficiency of Nur77 increases susceptibility to arterial thrombosis, whereas enhanced expression of Nur77 and Nor1 protects mice from arterial thrombus formation.

CONCLUSIONS

Our results identified nuclear receptors 4A as novel regulators of thrombomodulin expression and function in vascular ECs and provided a proof-of-concept demonstration that targeted increasing expression of Nur77 and Nor1 in the vascular endothelium might represent a novel therapeutic approach for the treatment of thrombotic disorders.

The association between statin therapy during intensive care unit stay and the incidence of venous thromboembolism: a propensity score-adjusted analysis

Background

Studies have shown that statins have pleiotropic effects on inflammation and coagulation; which may affect the risk of developing venous thromboembolism (VTE). The objective of this study was to evaluate the association between statin therapy during intensive care unit (ICU) stay and the incidence of VTE in critically ill patients.

Methods

This was a post-hoc analysis of a prospective observational cohort study of patients admitted to the intensive care unit between July 2006 and January 2008 at a tertiary care medical center. The primary endpoint was the incidence of VTE during ICU stay up to 30 days. Secondary endpoint was overall 30-day hospital mortality. Propensity score was used to adjust for clinically and statistically relevant variables.

Results

Of the 798 patients included in the original study, 123 patients (15.4%) received statins during their ICU stay. Survival analysis for VTE risk showed that statin therapy was not associated with a reduction of VTE incidence (crude hazard ratio (HR) 0.66, 95% confidence interval (CI) 0.28-1.54, P = 0.33 and adjusted HR 0.63, 95% CI 0.25-1.57, P = 0.33). Furthermore, survival analysis for hospital mortality showed that statin therapy was not associated with a reduction in hospital mortality (crude HR 1.26, 95% CI 0.95-1.68, P = 0.10 and adjusted HR 0.98, 95% CI 0.72-1.36, P = 0.94).

Conclusion

Our study showed no statistically significant association between statin therapy and VTE risk in critically ill patients. This question needs to be further studied in randomized control trials.

Statin treatment and the risk of recurrent pulmonary embolism

AIMS

Patients with idiopathic venous thromboembolism (VTE) have a high recurrence risk during and after stopping anticoagulant treatment. Several studies suggest that treatment with statins reduces the incidence of a first episode of VTE, but data on the effects in patients with a previous episode are lacking. We examined the effect of statin therapy on the risk of recurrent pulmonary embolism (PE).

METHODS AND RESULTS

Using the PHARMO Record Linkage System, a Dutch population-based registry of pharmacy records linked with hospital discharge records, patients hospitalized with an acute episode of PE were identified between 1998 and 2008. Prescription-based use of statins and vitamin K antagonist (VKA) were identified starting at hospital discharge and during follow-up. The association between statin use (time-varying) and the incidence of recurrences, cardiovascular events, and death was assessed using Cox regression analysis. The mean (standard deviation) age was 61 (17) years. The median (range) duration of VKA treatment after acute PE was 199 (45-3793) days. Twenty-four per cent of the patients (n = 737) had at least one prescription of statins during the follow-up period and the median duration of statin therapy was 1557 (5-4055) days. During a median follow-up of 1529 (1-4155) days, 285 (9.2%) patients experienced a recurrence. Treatment with statins was associated with a reduced risk of recurrent PE [adjusted hazard ratio (HR) 0.50, 95% CI: 0.36-0.70], both during and after stopping VKA treatment. A dose-response relationship was shown for potency, with the largest reduction in those with the most potent statins. Finally, statin treatment also reduced the risk for cardiovascular events and all-cause mortality.

CONCLUSION

Statin treatment decreases the risk of recurrent PE, irrespective of VKA treatment. Treatment with statins may be an attractive alternative for anticoagulant treatment in the long-term treatment of PE.

Statins for the prevention of venous thromboembolism? a narrative review

Venous thromboembolism (VTE), including deep vein thrombosis and pulmonary embolism, is a substantial public health problem. The majority of VTE events are associated with transient periods of heightened risk, such as prolonged hospitalization, undergoing major surgery, experiencing trauma or lower extremity immobility, use of oral contraceptives, or having active cancer. Although pharmacologic thromboprophylaxis agents (eg, unfractionated heparin, low-molecular-weight heparins, warfarin, and novel oral anticoagulants) are effective, they remain underused, with concerns about increased bleeding risk often cited as a reason. The 3-hydroxy-3-methylglutaryl-coenzyme A reductase inhibitors (ie, statins), although used primarily for lipid lowering and arterial thrombosis risk reduction, have pleiotrophic effects that affect coagulation and inflammation, and do not increase bleeding risk. There is emerging evidence to suggest that through these pleiotrophic effects, statins may be effective in reducing the incidence of VTE. This article summarizes the literature with regard to statins' effect on VTE and suggests that additional investigations are needed to assess a potential adjunctive role for primary VTE thromboprophylaxis.

Statins, inflammation and deep vein thrombosis: a systematic review

Venous thromboembolism (VTE) includes both deep vein thrombosis (DVT) and pulmonary embolism. The 2009 JUPITER trial showed a significant decrease in DVT in non-hyperlipidemic patients, with elevated C-reactive protein (CRP) levels, treated with rosuvastatin. The effects of statins on thrombosis are unclear, prompting this literature review. A literature search was performed (1950 to February 2011) with MEDLINE, EMBASE, and PUBMED databases including the following keywords: "statins", "hydroxymethylglutaryl-CoA reductase inhibitors", "VTE", "PE", "DVT", and either "anti-coagulation" or "inflammation". Editorials, reviews, case reports, meta-analysis and duplicates were excluded. Inflammatory biomarkers of DVT, include interleukin (IL)-6, CRP, IL-8, and monocyte chemotactic protein 1 (MCP-1). Statin therapy reduces IL-6 expression of CRP and MCP-1, usually elevated in VTE. Reduction of IL-6 induced MCP-1 has been linked to vein wall fibrosis, promoting post thrombotic syndrome (PTS) and recurrent DVT in patients. Also, our review suggests that the anti-thrombotic effects are likely exhibited through the anti-inflammatory properties of statins. This work supports that statin therapy has the ability to decrease the incidence and recurrence of VTE and the potential to decrease PTS. This is mainly due to the anti-inflammatory effects of statins and may explain why normolipidemic patients, with elevated CRP, appear to have the greatest reduction in VTE. Given their low risk of bleeding, statins have the potential to serve as a safe adjunctive pharmacological therapy to current treatments in select patients with VTE, however further investigations into this concept are needed and essential.

Krüppel-like factor 2 suppression by high glucose as a possible mechanism of diabetic vasculopathy

BACKGROUND AND OBJECTIVES

Endothelial dysfunction is widely observed in diabetes mellitus, resulting in diabetic vascular complications. Krüppel-like factor 2 (KLF2) is implicated as being a key molecule that maintains endothelial function. We evaluated the expression of KLF2 in endothelial cells cultured in high glucose and investigated its functional implication in a diabetic animal model.

SUBJECTS AND METHODS

Human umbilical vein endothelial cells (HUVECs) were cultured in physiologically high glucose (35 mM) condition. The Otsuka Long Evans Tokushima Fatty (OLETF) strain of rat was used as an excellent model of obese type II diabetes, and their lean littermates are Long Evans Tokushima Otsuka (LETO) rats.

RESULTS

In HUVECs cultured in physiologically high glucose condition, FOXO1 was activated whereas KLF2 and endothelial nitric oxide synthase (eNOS) expression was near completely abolished, which was completely reversed by FOXO1 small interfering ribonucleic acid. In the vessels harvested from the OLETF rats, the animal model of type II diabetes, KLF2 and eNOS expression were found depleted. When vascular remodeling was induced in the left common carotid artery by reduction of blood flow with partial ligation of the distal branches, greater neointimal hypertrophy was observed in OLETF rats compared with the control LETO rats.

CONCLUSION

KLF2 suppression in endothelial cells by high glucose is a possible mechanism of diabetic endothelial dysfunction. The strategy of replenishing KLF2 may be effective for preventing diabetic vascular dysfunction.

High-sensitivity C-reactive protein is not a risk factor for venous thromboembolism: the Tromso study

BACKGROUND

High-sensitivity C-reactive protein is associated with risk of arterial cardiovascular disease but conflicting results have been reported on its role in venous thromboembolic disease. The objective of our study was to investigate the association between high-sensitivity C-reactive protein levels and risk of future venous thromboembolism in a prospective cohort recruited from a general population.

DESIGN AND METHODS

High-sensitivity C-reactive protein was measured in serum samples from 6,426 men and women, aged 25-84 years, recruited from the Tromsø Study in the period 1994-1995. Incident venous thromboembolism events (n=209) were registered during a median of 12.5 years of follow up. Cox's proportional hazards regression models were used to estimate age- and gender-and multivariable-adjusted hazard ratios with 95% confidence intervals for total venous thromboembolism, and for provoked and unprovoked venous thromboembolism by increasing levels of high-sensitivity C-reactive protein.

RESULTS

There was no increased risk of venous thromboembolism per 1 standard deviation increase in high-sensitivity C-reactive protein (hazard ratio 1.08; 95% confidence interval 0.95-1.23) or across quartiles of high-sensitivity C-reactive protein (P for trend 0.6) in analyses adjusted for age and gender. Further adjustment for body mass index, smoking and diabetes did not alter the risk estimates. Moreover, high-sensitivity C-reactive protein was not associated with venous thromboembolism in either gender specific analysis or in separate analyses of provoked and unprovoked venous thromboembolism events.

CONCLUSIONS

In this prospective study, serum levels of high-sensitivity C-reactive protein were not associated with future development of venous thromboembolism. Our findings do not suggest a causal role for C-reactive protein in the pathogenesis of venous thromboembolism.

Cardiovascular risk factors and collateral artery formation

Arterial lumen narrowing and vascular occlusion is the actual cause of morbidity and mortality in atherosclerotic disease. Collateral artery formation (arteriogenesis) refers to an active remodelling of non-functional vascular anastomoses to functional collateral arteries, capable to bypass the site of obstruction and preserve the tissue that is jeopardized by ischaemia. Hemodynamic forces such as shear stress and wall stress play a pivotal role in collateral artery formation, accompanied by the expression of various cytokines and invasion of circulating leucocytes. Arteriogenesis hence represents an important compensatory mechanism for atherosclerotic vessel occlusion. As arteriogenesis mostly occurs when lumen narrowing by atherosclerotic plaques takes place, presence of cardiovascular risk factors (e.g. hypertension, hypercholesterolaemia and diabetes) is highly likely. Risk factors for atherosclerotic disease affect collateral artery growth directly and indirectly by altering hemodynamic forces or influencing cellular function and proliferation. Adequate collateralization varies significantly among atherosclerotic patients, some profit from the presence of extensive collateral networks, whereas others do not. Cardiovascular risk factors could increase the risk of adverse cardiovascular events in certain patients because of the reduced protection through an alternative vascular network. Likewise, drugs primarily thought to control cardiovascular risk factors might contribute or counteract collateral artery growth. This review summarizes current knowledge on the influence of cardiovascular risk factors and the effects of cardiovascular medication on the development of collateral vessels in experimental and clinical studies.

Molecular and cellular mechanisms of the thrombotic complications of atherosclerosis

Clinicians have traditionally regarded the complications of atherosclerosis as a consequence of progressive arterial stenosis leading to critical narrowings that impede blood flow. Our contemporary understanding of the thrombotic complications of atherosclerosis has undergone a transformation based on a body of observations by pathologists and clinicians. In the late 1980s, clinicians had to confront the counterintuitive notion that plaques that cause acute myocardial infarction often do not produce high-grade stenoses (Smith, S. C., Jr. 1996. Risk-reduction therapy: the challenge to change. Circulation. 93: 2205-2211.). Observations from serial angiographic studies and on culprit lesions of acute myocardial infarction postthrombolysis highlighted this apparent paradox. These contrarian clinical findings prompted cardiologists to consider more carefully the findings of generations of pathologists that plaques that cause fatal coronary thrombi often result from a physical disruption of the atheromatous plaque that may not indeed cause critical arterial narrowing. This convergence of clinical and pathological observations highlighted the importance of understanding the mechanisms of disruption of plaques that can precipitate thromboses.