Usefulness of soluble Fms-like tyrosine kinase-1 as a biomarker of acute severe heart failure in patients with acute myocardial infarction

Soluble FLT-1 in angiogenesis: pathophysiological roles and therapeutic implications

Fine-tuning angiogenesis, the development of new blood vessels, is essential for maintaining a healthy circulatory and lymphatic system. The small glycoprotein vascular endothelial growth factors (VEGF) are the key mediators in this process, binding to their corresponding membrane-bound VEGF receptors (VEGFRs) to activate angiogenesis signaling pathways. These pathways are crucial throughout human life as they are involved in lymphatic and vascular endothelial cell permeability, migration, proliferation, and survival. Neovascularization, the formation of abnormal blood vessels, occurs when there is a dysregulation of angiogenesis and can result in debilitating disease. Hence, VEGFRs have been widely studied to understand their role in disease-causing angiogenesis. VEGFR1, also known as Fms-like tyrosine kinase-1 (FLT-1), is also found in a soluble form, soluble FLT-1 or sFLT-1, which is known to act as a VEGF neutralizer. It is incorporated into anti-VEGF therapy, designed to treat diseases caused by neovascularization. Here we review the journey of sFLT-1 discovery and delve into the alternative splicing mechanism that creates the soluble receptor, its prevalence in disease states, and its use in current and future potential therapies.

Ergothioneine improves myocardial remodeling and heart function after acute myocardial infarction via S-glutathionylation through the NF-ĸB dependent Wnt5a-sFlt-1 pathway

Myocardial infarction (MI) remains the leading cause of cardiovascular death worldwide. Studies have shown that soluble fms-like tyrosine kinase-1 (sFlt-1) has a harmful effect on the heart after MI. However, ergothioneine (ERG) has been shown to have protective effects in rats with preeclampsia by reducing circulating levels of sFlt-1. In this study, we aimed to investigate the mechanism by which ERG protects the heart after MI in rats. Our results indicate that treatment with 10 mg/kg ERG for 7 days can improve cardiac function as determined by echocardiography. Additionally, ERG can reduce the size of the damaged area, prevent heart remodeling, fibrosis, and reduce cardiomyocyte death after MI. To explain the mechanism behind the cardioprotective effects of ERG, we conducted several experiments. We observed a significant reduction in the expression of monocyte chemoattractant protein-1 (MCP-1), p65, and p-p65 proteins in heart tissues of ERG-treated rats compared to the control group. ELISA results also showed that ERG significantly reduced plasma levels of sFlt-1. Using Glutaredoxin-1 (GLRX) and CD31 immunofluorescence, we found that GLRX was expressed in clusters in the myocardial tissue surrounding the coronary artery, and ERG can reduce the expression of GLRX caused by MI. In vitro experiments using a human coronary artery endothelial cell (HCAEC) hypoxia model confirmed that ERG can reduce the expression of sFlt-1, GLRX, and Wnt5a. These findings suggest that ERG protects the heart from MI damage by reducing s-glutathionylation through the NF-ĸB-dependent Wnt5a-sFlt-1 pathway.

The Soluble Fms-like Tyrosine Kinase-1 Contributes to Structural and Functional Changes in Endothelial Cells in Chronic Kidney Disease

Endothelial cells are a critical target of the soluble Fms-like tyrosine kinase-1 (sFlt-1), a soluble factor increased in different diseases with varying degrees of renal impairment and endothelial dysfunction, including chronic kidney disease (CKD). Although the mechanisms underlying endothelial dysfunction are multifactorial and complex, herein, we investigated the damaging effects of sFlt-1 on structural and functional changes in endothelial cells. Our results evidenced that sera from patients with CKD stiffen the endothelial cell cortex in vitro, an effect correlated with sFlt-1 levels and prevented by sFlt-1 neutralization. Besides, we could show that recombinant sFlt-1 leads to endothelial stiffening in vitro and in vivo. This was accompanied by cytoskeleton reorganization and changes in the endothelial barrier function, as observed by increased actin polymerization and endothelial cell permeability, respectively. These results depended on the activation of the p38 MAPK and were blocked by the specific inhibitor SB203580. However, sFlt-1 only minimally affected the expression of stiffness-sensitive genes. These findings bring new insight into the mechanism of action of sFlt-1 and its biological effects that cannot be exclusively ascribed to the regulation of angiogenesis.

Novel Cardiovascular Biomarkers Associated with Increased Cardiovascular Risk in Women With Prior Preeclampsia/HELLP Syndrome: A Narrative Review

Evidence has shown that women with a history of preeclampsia or haemolysis, elevated liver enzymes and low platelets (HELLP) syndrome have an increased risk of cardiovascular disease later in life. Recommendations for screening, prevention and management after such pregnancies are not yet defined. The identification of promising non-traditional cardiovascular biomarkers might be useful to predict which women are at greatest risk. Many studies are inconsistent and an overview of the most promising biomarkers is currently lacking. This narrative review provides an update of the current literature on circulating cardiovascular biomarkers that may be associated with an increased cardiovascular disease risk in women after previous preeclampsia/HELLP syndrome. Fifty-six studies on 53 biomarkers were included. From the summary of evidence, soluble fms-like tyrosine kinase-1, placental growth factor, interleukin (IL)-6, IL-6/IL-10 ratio, high-sensitivity cardiac troponin I, activin A, soluble human leukocyte antigen G, pregnancy-associated plasma protein A and norepinephrine show potential and are interesting candidate biomarkers to further explore. These biomarkers might be potentially eligible for cardiovascular risk stratification after preeclampsia/HELLP syndrome and may contribute to the development of adequate strategies for prevention of hypertension and adverse events in this population.

Overexpression of sFlt-1 represses ox-LDL-induced injury of HUVECs by activating autophagy via PI3K/AKT/mTOR pathway

Soluble fms-like tyrosine kinase-1 (sFlt-1), a circulating antiangiogenic protein, is involved in the pathogenesis of atherosclerosis (AS), and the underlying mechanism is still unclear. Here, we attempted to investigate the mechanism of action of sFlt-1 in AS. Human umbilical vein endothelial cells (HUVECs) were treated with oxidized low density lipoprotein (ox-LDL) to induce cell injury. ox-LDL treatment increased LC3-II/LC3-I ratio, Beclin-1 expression and GFP-LC3 puncta in HUVECs, suggesting that ox-LDL may induce autophagic flux impairment in HUVECs. ox-LDL-treated HUVECs displayed a decrease of sFlt-1 levels. Moreover, ox-LDL treatment reduced cell proliferation and elevated apoptosis in HUVECs, which was abrogated by sFlt-1 overexpression. Up-regulation of sFlt-1 repressed the activity of PI3K/AKT/mTOR signaling pathway and enhanced autophagy in HUVECs following ox-LDL treatment. Additionally, sFlt-1 overexpression-mediated increase of autophagy in ox-LDL-treated HUVECs was abolished by 3-methyladenine (autophagy inhibitor). 3-methyladenine abrogated the impact of sFlt-1 overexpression on proliferation and apoptosis in ox-LDL-treated HUVECs. This work confirmed that overexpression of sFlt-1 activated autophagy by repressing PI3K/Akt/mTOR signaling pathway, and thus alleviated ox-LDL-induced injury of HUVECs. Therefore, this study suggests that sFlt-1 may be a potential target for AS treatment.

Circulating Soluble Fms-like Tyrosine Kinase in Renal Diseases Other than Preeclampsia

Soluble Fms-like tyrosine kinase (sFlt-1/sVEGFR1) is a naturally occurring antagonist of vascular endothelial growth factor (VEGF). Despite being a secreted, soluble protein lacking cytoplasmic and transmembrane domains, sFlt-1 can act locally and be protective against excessive microenvironmental VEGF concentration or exert autocrine functions independently of VEGF. Circulating sFlt-1 may indiscriminately affect endothelial function and the microvasculature of distant target organs. The clinical significance of excess sFlt-1 in kidney disease was first shown in preeclampsia, a major renal complication of pregnancy. However, circulating sFlt-1 levels appear to be increased in various diseases with varying degrees of renal impairment. Relevant clinical associations between circulating sFlt-1 and severe outcomes (e.g., endothelial dysfunction, renal impairment, cardiovascular disease, and all-cause mortality) have been observed in patients with CKD and after kidney transplantation. However, sFlt-1 appears to be protective against renal dysfunction-associated aggravation of atherosclerosis and diabetic nephropathy. Therefore, in this study, we provide an update on sFlt-1 in several kidney diseases other than preeclampsia, discuss clinical findings and experimental studies, and briefly consider its use in clinical practice.

Mechanistic Biomarkers Informative of Both Cancer and Cardiovascular Disease: JACC State-of-the-Art Review

Cardiovascular disease (CVD) and cancer are leading causes of morbidity and mortality worldwide. Although conventionally managed as separate disease processes, recent research has lent insight into compelling commonalities between CVD and cancer, including shared mechanisms for disease development and progression. In this review, the authors discuss several pathophysiological processes common to both CVD and cancer, such as inflammation, resistance to cell death, cellular proliferation, neurohormonal stress, angiogenesis, and genomic instability, in an effort to understand common mechanisms of both disease states. In particular, the authors highlight key circulating and genomic biomarkers associated with each of these processes, as well as their associations with risk and prognosis in both cancer and CVD. The purpose of this state-of-the-art review is to further our understanding of the potential mechanisms underlying cancer and CVD by contextualizing pathways and biomarkers common to both diseases.

Soluble Flt1 levels are associated with cardiac dysfunction in Black women with and without severe preeclampsia

Background: We evaluate soluble fms-like tyrosine kinase-1 (sFlt-1) levels and cardiac function during pregnancy and postpartum among Black women with and without preeclampsia. Study design: Prospective longitudinal cohort study from 2015 to 2017 of Black women with preterm severe preeclampsia and normotensive pregnant controls.We obtained echocardiograms and sFlt-1 levels during pregnancy and postpartum. Results: 93 Black women were included (43 cases, 50 controls). Higher sFlt1 levels were correlated with worse longitudinal strain, diastolic dysfunction, decreased ventricular-arterial coupling, and increased chamber and arterial elastance at the time of preeclampsia diagnosis and postpartum. Conclusions: Higher sFlt1 levels are associated with cardiovascular dysfunction during pregnancy and postpartum.

The role of the PlGF/Flt-1 signaling pathway in the cardiorenal connection

Although the concept of the cardiorenal connection is widely accepted, athe underlying molecular mechanism has not been clearly defined. Nevertheless, accumulating evidence indicates that the nervous system and both the humoral and cellular immune systems are all involved. This review article focuses on the roles of the signaling pathway of placental growth factor (PlGF) and its receptor, fms-like tyrosine kinase-1 (Flt-1), in the development of the cardiorenal connection. PlGF, a member of the vascular endothelial cell growth factor family, is a specific ligand for Flt-1 and plays roles in the development of atherosclerosis, wound healing after ischemia injury, and angiogenesis through Flt-1 signaling. Flt-1, a tyrosine-kinase type receptor with a single transmembrane domain, has a soluble isoform (sFlt-1) consisting of only extracellular domains, and is an intrinsic antagonist of PlGF. In renal dysfunction, PlGF is upregulated and sFlt-1 is downregulated by oxidative stress or uremic toxins, leading to activation of the PlGF/Flt-1 signaling pathway, which in turn plays a role in the worsening of atherosclerosis and heart failure, both of which are frequently associated with renal dysfunction. Monocyte chemotactic protein-1 (MCP-1) is involved in the process downstream of the Flt-1 signaling pathway. Plasma levels of sFlt-1 correlate with the severity of renal dysfunction in patients with heart failure or myocardial infarction, and are associated with the incidence of cardiovascular events. This is inconsistent with the concept of relative activation of the PlGF/Flt-1 pathway in renal dysfunction. However, the level of circulating sFlt-1 does not always parallel sFlt-1 synthesis, probably because sFlt-1 is stored on cell surfaces through its heparin-binding domains and its quantity is regulated differently in renal dysfunction. This review summarizes a novel concept wherein noninfectious inflammation via PlGF/Flt-1 signaling is involved in the development of renal dysfunction-related cardiovascular complications.

Unfractionated heparin displaces sFlt-1 from the placental extracellular matrix

Soluble vascular endothelial growth factor receptor-1 (sFlt-1) is an anti-angiogenic protein which is secreted by numerous cell types and acts as a decoy receptor for the angiogenic protein vascular endothelial growth factor (VEGF). Despite its physiologic importance in maintaining angiogenic balance, excess sFlt-1 levels are associated with the pathogenesis of many diseases, especially those with angiogenic imbalance, endothelial dysfunction, and hypertension. Although sFlt-1 is a soluble protein, it contains a binding site for the extracellular matrix component heparan sulfate. This allows cells to retain and localize sFlt-1 in order to prevent excessive VEGF signaling. During pregnancy, placental syncytiotrophoblasts develop a large extracellular matrix which contains significant amounts of heparan sulfate. Consequently, the placenta becomes a potential storage site for large amounts of sFlt-1 bound to extracellular heparan sulfate. Additionally, it should be noted that sFlt-1 can bind to the anticoagulant unfractionated heparin due to its molecular mimicry to heparan sulfate. However, it remains unknown whether unfractionated heparin can compete with heparan sulfate for binding of localized sFlt-1. In this study, we hypothesized that administration of unfractionated heparin would displace and solubilize placental extracellular matrix(ECM)-bound sFlt-1. If unfractionated heparin can displace this large reservoir of sFlt-1 in the placenta and mobilized it into the maternal circulation, we should be able to observe its effects on maternal angiogenic balance and blood pressure. To test this hypothesis, we utilized in vitro, ex vivo, and in vivo methods. Using the BeWo placental trophoblast cell line, we observed increased sFlt-1 in the media of cells treated with unfractionated heparin compared to controls. The increase in media sFlt-1 was found in conjunction with decreased localized cellular Flt (sFlt-1 and Flt-1) as measured by total cell fluorescence. Similar results were observed using ex vivo placental villous explants treated with unfractionated heparin. Real-time quantitative PCR of the explants showed no change in sFlt-1 or heparanase-1 mRNA expression, eliminating increased production and enzymatic cleavage of heparan sulfate as causes for sFlt-1 media increase. Timed-pregnant rats given a continuous infusion of unfractionated heparin exhibited an increased mean arterial pressure as well as decreased bioavailable VEGF compared to vehicle-treated animals. These data demonstrate that chronic unfractionated heparin treatment is able to displace matrix-bound sFlt-1 into the maternal circulation to such a degree that mean arterial pressure is significantly affected. Here we have shown that the placental ECM is a storage site for large quantities of sFlt-1, and that it should be carefully considered in future studies concerning angiogenic balance in pregnancy.

A Systematic Review of Vascular Structure and Function in Pre-eclampsia: Non-invasive Assessment and Mechanistic Links

Hypertensive disorders of pregnancy, such as pre-eclampsia, are known to be independently associated with the development of premature cardiovascular disease (CVD) in women. In pre-eclampsia, the placenta secretes excess anti-angiogenic factors into the maternal circulation, leading to widespread endothelial damage, and inflammation. This endothelial damage is evidenced to persist beyond the acute illness. However, whether it is permanent and responsible for the elevated rates of premature CVD seen in this at-risk group remains unclear. A systematic review of the available literature with respect to vascular structure and function prior to, during and after a pregnancy complicated by pre-eclampsia was performed. Studies non-invasively assessing vascular structure using carotid intima-media thickness (CIMT), retinal microvasculature caliber, CT coronary angiogram, or coronary calcium scores were included. Vascular function was assessed using brachial flow-mediated dilation (FMD), pulse wave analysis (PWA), and peripheral arterial tonometry (PAT). In total 59 articles were included (13 CIMT, 5 CTCA/Ca score, five retinal microvasculature, 27 FMD, 7 PAT, and 14 PWV/PWA), consisting of prospective and retrospective cohort, and case-control studies. Change in vascular structure was evidenced with significant increases in CIMT by 73-180 μm greater than that of non-affected women. This is tempered by other studies reporting resolution of structural changes postpartum, highlighting the need for further research. Accelerated coronary calcification and plaque deposition was identified, with greater rates of increased calcium scores and subclinical coronary artery disease shown by CTCA in women with a history of pre-eclampsia at 30 years postpartum. Impaired endothelial function was consistently reported prior to, during and immediately after pregnancy as evidenced by differences in FMD of 1.7-12.2% less than non-affected women, an increase in PWV by 13.2-26%, and reduced retinal microvascular caliber and arterial elasticity indices. The evidence was less conclusive for the persistence of long-term endothelial dysfunction. Understanding the underlying mechanistic links between pre-eclampsia and CVD is a key step to identifying targeted therapies aimed at "repairing the endothelium" and attenuating risk. This review has highlighted the need for a greater understanding of vascular structure and function following pre-eclampsia through high quality studies with large sample sizes, particularly in the longer postpartum period when clinical CVD disease starts to manifest.

A Systematic Review of Vascular Structure and Function in Pre-eclampsia: Non-invasive Assessment and Mechanistic Links

Hypertensive disorders of pregnancy, such as pre-eclampsia, are known to be independently associated with the development of premature cardiovascular disease (CVD) in women. In pre-eclampsia, the placenta secretes excess anti-angiogenic factors into the maternal circulation, leading to widespread endothelial damage, and inflammation. This endothelial damage is evidenced to persist beyond the acute illness. However, whether it is permanent and responsible for the elevated rates of premature CVD seen in this at-risk group remains unclear. A systematic review of the available literature with respect to vascular structure and function prior to, during and after a pregnancy complicated by pre-eclampsia was performed. Studies non-invasively assessing vascular structure using carotid intima-media thickness (CIMT), retinal microvasculature caliber, CT coronary angiogram, or coronary calcium scores were included. Vascular function was assessed using brachial flow-mediated dilation (FMD), pulse wave analysis (PWA), and peripheral arterial tonometry (PAT). In total 59 articles were included (13 CIMT, 5 CTCA/Ca score, five retinal microvasculature, 27 FMD, 7 PAT, and 14 PWV/PWA), consisting of prospective and retrospective cohort, and case-control studies. Change in vascular structure was evidenced with significant increases in CIMT by 73–180 μm greater than that of non-affected women. This is tempered by other studies reporting resolution of structural changes postpartum, highlighting the need for further research. Accelerated coronary calcification and plaque deposition was identified, with greater rates of increased calcium scores and subclinical coronary artery disease shown by CTCA in women with a history of pre-eclampsia at 30 years postpartum. Impaired endothelial function was consistently reported prior to, during and immediately after pregnancy as evidenced by differences in FMD of 1.7–12.2% less than non-affected women, an increase in PWV by 13.2–26%, and reduced retinal microvascular caliber and arterial elasticity indices. The evidence was less conclusive for the persistence of long-term endothelial dysfunction. Understanding the underlying mechanistic links between pre-eclampsia and CVD is a key step to identifying targeted therapies aimed at “repairing the endothelium” and attenuating risk. This review has highlighted the need for a greater understanding of vascular structure and function following pre-eclampsia through high quality studies with large sample sizes, particularly in the longer postpartum period when clinical CVD disease starts to manifest.

Preeclampsia: Maternal Systemic Vascular Disorder Caused by Generalized Endothelial Dysfunction Due to Placental Antiangiogenic Factors

Preeclampsia, a systemic vascular disorder characterized by new-onset hypertension and proteinuria after 20 weeks of gestation, is the leading cause of maternal and perinatal morbidity and mortality. Maternal endothelial dysfunction caused by placental factors has long been accepted with respect to the pathophysiology of preeclampsia. Over the past decade, increased production of placental antiangiogenic factors has been identified as a placental factor leading to maternal endothelial dysfunction and systemic vascular dysfunction. This review summarizes the recent advances in understanding the molecular mechanisms of endothelial dysfunction caused by placental antiangiogenic factors, and the novel clinical strategies based on these discoveries.

Placenta growth factor and sFlt-1 as biomarkers in ischemic heart disease and heart failure: a review

Coronary heart disease (CHD) and heart failure (HF) produce significant morbidity/mortality but identifying new biomarkers could help in the management of each. In this article, we summarize the molecular regulation and biomarker potential of PIGF and sFlt-1 in CHD and HF. PlGF is elevated during ischemia and some studies have shown PlGF, sFlt-1 or PlGF:sFlt-1 ratio, when used in combination with standard biomarkers, strengthens predictions of outcomes. sFlt-1 and PlGF are elevated in HF with sFlt-1 as a stronger predictor of outcomes. Although promising, we discuss additional study criteria needed to confirm the clinical usefulness of PlGF or sFlt-1 in the detection and management of CHD or HF.

Novel biochemical predictors of unfavorable prognosis for stable coronary disease

Successful risk stratification is necessary for optimum management of patients after acute coronary syndrome (ACS). The aim of the study was to evaluate the role of novel biochemical markers in the prediction of adverse cardiovascular events in stable patients several years after ACS.The study group was randomly selected from all ACS patients treated with reperfusion therapy between 2002 and 2003 at 1st Department of Cardiology, Medical University of Warsaw, Poland. All patients were readmitted to hospital between 2010 and 2011 for clinical and biochemical cardiovascular risk factors assessment and were prospectively observed for 30-months follow-up. The primary endpoint was all-cause death or hospital readmissions due to a cardiovascular condition at 30 months. The secondary endpoint was a composite of all-cause death or hospitalization-related noncardiovascular condition during the follow-up.The study population consisted of 146 patients (mean age 66.6 ± 9.8 years; 60 female). The primary and secondary endpoints occurred in 49 and 65 patients, respectively. Univariate analysis demonstrated that out of 17 analyzed biomarkers only high-sensitive C-reactive protein (hsCRP), Soluble Fms-Like Tyrosine kinase-1 (sFlt-1), and endothelin-1 (ET-1) were significantly associated with primary end-point and N-Terminal pro-B-type natriuretic peptide (NT-proBNP), hsCRP, ET-1, sFlt-1, and procalcitonin (PCT)-with secondary end-point. Multivariate analysis demonstrated that concentration of sFlt-1 was the only independent factor associated with primary end-point (P = .007 and P = .025, respectively), whereas NT-proBNP and hsCRP levels were only associated with secondary end-point (P = .004 and P = .001, respectively).sFlt-1, NT-proBNP, and hsCRP are associated with adverse outcomes in stable patients several years after ACS and may emerge as useful clinical biomarkers to enhance stratify patient's risk.

Novel concept to guide systolic heart failure medication by repeated biomarker testing-results from TIME-CHF in context of predictive, preventive, and personalized medicine

Background

It is uncertain whether repeated measurements of a multi-target biomarker panel may help to personalize medical heart failure (HF) therapy to improve outcome in chronic HF.

Methods

This analysis included 499 patients from the Trial of Intensified versus standard Medical therapy in Elderly patients with Congestive Heart Failure (TIME-CHF), aged ≥ 60 years, LVEF ≤ 45%, and NYHA ≥ II, who had repeated clinical visits within 19 months follow-up. The interaction between repeated measurements of biomarkers and treatment effects of loop diuretics, spironolactone, β-blockers, and renin-angiotensin system (RAS) inhibitors on risk of HF hospitalization or death was investigated in a hypothesis-generating analysis. Generalized estimating equation (GEE) models were used to account for the correlation between recurrences of events in a patient.

Results

One hundred patients (20%) had just one event (HF hospitalization or death) and 87 (17.4%) had at least two events. Loop diuretic up-titration had a beneficial effect for patients with high interleukin-6 (IL6) or high high-sensitivity C-reactive protein (hsCRP) (interaction, P = 0.013 and P = 0.001), whereas the opposite was the case with low hsCRP (interaction, P = 0.013). Higher dosage of loop diuretics was associated with poor outcome in patients with high blood urea nitrogen (BUN) or prealbumin (interaction, P = 0.006 and P = 0.001), but not in those with low levels of these biomarkers. Spironolactone up-titration was associated with lower risk of HF hospitalization or death in patients with high cystatin C (CysC) (interaction, P = 0.021). β-Blockers up-titration might have a beneficial effect in patients with low soluble fms-like tyrosine kinase-1 (sFlt) (interaction, P = 0.021). No treatment biomarker interactions were found for RAS inhibition.

Conclusion

The data of this post hoc analysis suggest that decision-making using repeated biomarker measurements may be very promising in bringing treatment of heart failure to a new level in the context of predictive, preventive, and personalized medicine. Clearly, prospective testing is needed before this novel concept can be adopted.

Clinical trial registration

isrctn.org, identifier: ISRCTN43596477

Electronic supplementary material

The online version of this article (10.1007/s13167-018-0137-7) contains supplementary material, which is available to authorized users.

Association between angiogenic factors and signs of arterial aging in women with pre-eclampsia

OBJECTIVE

Pre-eclampsia (PE) is associated with an increased risk of cardiovascular disease later in life. In cases with PE there is a substantial increase in levels of the antiangiogenic factor soluble fms-like tyrosine kinase-1 (sFlt-1) and decreased levels of the proangiogenic factor placental growth factor (PlGF). Elevated levels of sFlt-1 are also found in individuals with cardiovascular disease. The aims of this study were to assess levels of sFlt-1, PlGF and the sFlt-1/PlGF ratio and their correlation with signs of arterial aging by measuring the common carotid artery (CCA) intima and media thicknesses and their ratio (I/M ratio) in women with and without PE.

METHODS

Serum sFlt-1 and PlGF levels were measured using commercially available enzyme-linked immunosorbent assay kits, and CCA intima and media thicknesses were estimated using high-frequency (22-MHz) ultrasonography in 55 women at PE diagnosis and in 64 women with normal pregnancy at a similar gestational age, with reassessment at 1 year postpartum.

RESULTS

During pregnancy, higher levels of sFlt-1, lower levels of PlGF, a thicker intima, a thinner media and a higher I/M ratio of the CCA were found in women with PE vs controls (all P < 0.0001). Further, sFlt-1 and the sFlt-1/PlGF ratio were positively correlated with intima thickness and I/M ratio (all P < 0.0001). At 1 year postpartum, levels of sFlt-1 and the sFlt-1/PlGF ratio had decreased in both groups; however, their levels in the PE group were still higher than in the controls (P = 0.001 and < 0.0001, respectively). Levels of sFlt-1 and the sFlt-1/PlGF ratio remained positively correlated with intima thickness and I/M ratio at 1 year postpartum.

CONCLUSIONS

Higher sFlt-1 levels and sFlt-1/PlGF ratio in women with PE were positively associated with signs of arterial aging during pregnancy. At 1 year postpartum, sFlt-1 levels and the sFlt-1/PlGF ratio were still higher in the PE group and were associated with the degree of arterial aging. © 2016 The Authors. Ultrasound in Obstetrics & Gynecology published by John Wiley & Sons Ltd on behalf of the International Society of Ultrasound in Obstetrics and Gynecology.

Protective Low-Frequency Variants for Preeclampsia in the Fms Related Tyrosine Kinase 1 Gene in the Finnish Population

Preeclampsia is a common pregnancy-specific vascular disorder characterized by new-onset hypertension and proteinuria during the second half of pregnancy. Predisposition to preeclampsia is in part heritable. It is associated with an increased risk of cardiovascular disease later in life. We have sequenced 124 candidate genes implicated in preeclampsia to pinpoint genetic variants contributing to predisposition to or protection from preeclampsia. First, targeted exomic sequencing was performed in 500 preeclamptic women and 190 controls from the FINNPEC cohort (Finnish Genetics of Preeclampsia Consortium). Then 122 women with a history of preeclampsia and 1905 parous women with no such history from the National FINRISK Study (a large Finnish population survey on risk factors of chronic, noncommunicable diseases) were included in the analyses. We tested 146 rare and low-frequency variants and found an excess (observed 13 versus expected 7.3) nominally associated with preeclampsia (P<0.05). The most significantly associated sequence variants were protective variants rs35832528 (E982A; P=2.49E-4; odds ratio=0.387) and rs141440705 (R54S; P=0.003; odds ratio=0.442) in Fms related tyrosine kinase 1. These variants are enriched in the Finnish population with minor allele frequencies 0.026 and 0.017, respectively. They may also be associated with a lower risk of heart failure in 11 257 FINRISK women. This study provides the first evidence of maternal protective genetic variants in preeclampsia.

Improved risk stratification of patients with acute coronary syndromes using a combination of hsTnT, NT-proBNP and hsCRP with the GRACE score

Background:

Clinical scores and biomarkers improve risk stratification of patients with acute coronary syndromes. However, little is known about their value in patients referred for coronary angiography.

Methods:

Consecutive patients admitted at four Swiss university hospitals with a diagnosis of acute coronary syndrome were enrolled into the SPUM-ACS Biomarker Cohort between 2009 and 2012. Patients were followed at 30 days and 1 year with assessment of adjudicated events including all-cause mortality and the composite of all-cause mortality or non-fatal recurrent myocardial infarction.

Results:

Events and biomarkers were analysed in 1892 patients (52.4% with ST-segment elevation myocardial infarction, 43.3% with non-ST-segment elevation myocardial infarction and 4.3% with unstable angina). Death at 30 days occurred in 35 patients (1.9%) and at 1 year in 80 patients (4.3%). The choice of troponin assay (conventional versus high sensitivity) to calculate the Global Registry of Acute Coronary Events (GRACE) score did not affect risk prediction. The prognostic accuracy of the GRACE score was improved when combined with three individual biomarkers including high sensitivity troponin T (hsTnT), N-terminal-pro B-type natriuretic peptide (NT-proBNP) and high sensitivity C-reactive protein (hsCRP) to yield a 9% increment (C-statistic 0.73–>0.82) for the discrimination of short-term risk for all-cause mortality. In contrast, the novel biomarkers placental growth factor (PlGF), soluble fms-like tyrosine kinase-1 (sFlt-1) and the ratio sFlt-1/PlGF did not improve risk stratification.

Conclusions:

In patients with acute coronary syndrome referred for coronary angiography, combinations of biomarkers including hsTnT, NT-proBNP and hsCRP with the GRACE score enhanced risk discrimination.

Clinical Trials Registration:

NCT01000701

Serum Soluble Fms-Like Tyrosine Kinase 1 (sFlt-1) Predicts the Severity of Acute Pancreatitis

Organ failure is the most important determinant of the severity of acute pancreatitis (AP). Soluble fms-like tyrosine kinase 1 (sFlt-1) is positively associated with organ failure in sepsis. Our aim was to evaluate the diagnostic utility of automated sFlt-1 measurements for early prediction of AP severity. Adult patients (66) with AP were recruited, including 46 with mild (MAP), 15 with moderately-severe (MSAP) and 5 with severe AP (SAP). Serum and urine samples were collected twice. Serum sFlt-1 was measured with automated electrochemiluminescence immunoassay. Serum concentrations of sFlt-1 were significantly higher in patients with MSAP and SAP as compared to MAP. SAP patients had the highest concentrations. At 24 and 48 h, sFlt-1 positively correlated with inflammatory markers (leukocyte count, C-reactive protein), kidney function (creatinine, urea, cystatin C, serum and urine neutrophil gelatinase-associated lipocalin, urine albumin/creatinine ratio), D-dimer and angiopoietin-2. sFlt-1 positively correlated with the bedside index of severity in AP (BISAP) score and the duration of hospital stay. Serum sFlt-1 above 139 pg/mL predicted more severe AP (MSAP + SAP). In the early phase of AP, sFlt-1 is positively associated with the severity of AP and predicts organ failure, in particular kidney failure. Serum sFlt-1 may be a practical way to improve early assessment of AP severity.

Pathophysiology of preeclampsia: an angiogenic imbalance and long-lasting systemic vascular dysfunction

Preeclampsia is a systemic vascular disorder characterized by new-onset hypertension and proteinuria after 20 weeks of gestation. This condition targets several organs, including the kidneys, liver and brain, and is the leading cause of maternal and perinatal morbidity and mortality. Furthermore, recent evidence has revealed preeclampsia as a significant risk factor for future cardiovascular diseases in these women. Over the past decade, increasing evidence has indicated that maternal angiogenic imbalances caused by placental antiangiogenic factors play a central role in the systemic vascular dysfunction underling preeclampsia. The severity of the maternal antiangiogenic state correlates closely with maternal and perinatal outcomes. Assessing angiogenic imbalance and several vascular function tests have also emerged as a way of detecting systemic vascular dysfunction during pregnancy. This review summarizes the current understanding of the pathophysiology of preeclampsia, its clinical applications and clinical evidence for future cardiovascular risks.

Angiogenic Factors and Risks of Technique Failure and Cardiovascular Events in Patients Receiving Peritoneal Dialysis

BACKGROUND

Placental growth factor (PlGF) is a member of the vascular endothelial growth factor family that acts as a pleiotropic cytokine capable of stimulating angiogenesis and accelerating atherogenesis. Soluble fms-like tyrosine kinase-1 (sFlt-1) antagonizes PlGF action. Higher levels of PlGF and sFlt-1 have been associated with cardiovascular events in patients with chronic kidney disease, yet little is known about their relationship with adverse outcomes in patients on peritoneal dialysis (PD). The aim of this study was to investigate the association of PlGF and sFlt-1 with technique survival and cardiovascular events.

METHODS

We measured serum levels of PlGF and plasma levels of sFlt-1 in 40 PD patients at Nara Medical University.

RESULTS

PlGF and sFlt-1 levels were significantly correlated with the dialysate-to-plasma ratio of creatinine (r = 0.342, p = 0.04 and r = 0.554, p < 0.001) although PlGF and sFlt-1 levels were not correlated with total creatinine clearance and total Kt/V. Additionally, both PlGF and sFlt-1 levels were significantly higher in patients with high transport membranes compared to those without (p = 0.039 and p < 0.001, respectively). Patients with PlGF levels above the median had lower technique survival and higher incidence of cardiovascular events than patients with levels below the median, with hazard ratios of 11.9 and 7.7, respectively, in univariate Cox regression analysis. However, sFlt-1 levels were not associated with technique survival or cardiovascular events (p = 0.11 and p = 0.10, respectively).

CONCLUSION

Elevated PlGF and sFlt-1 are significantly associated with high transport membrane status. PlGF may be a useful predictor of technique survival and cardiovascular events in PD patients.

Prognostic use of soluble fms-like tyrosine kinase-1 and placental growth factor in patients with coronary artery disease

Background: Intention of the study is to assess the cardiovascular mortality of patients with coronary artery disease (CAD) with the biomarkers of angiogenesis PlGF and its endogenous inhibitor sFlt-1. Methods: The cohort included n = 1848 patients with CAD and 282 subjects without CAD. In 85 patients cardiovascular mortality, as combination of fatal myocardial infarction or any cardiac death, during a median follow-up duration of 3.9 years was reported. Results: In Kaplan–Meier curve analysis PlGF in rising thirds was not predictive regarding outcome (p = 0.54), the same was shown for sFlt-1 (p = 0.44). Cox regression for the fully adjusted model provided a hazard ratio (HR) of 0.8 (p = 0.18) for PlGF and for sFlt-1 a HR = 1.0 (p = 0.8). Conclusion: Our results point out that these biomarkers reflecting angiogenesis might not be suited to establish prognosis in CAD.

Elevated Soluble Fms-Like Tyrosine Kinase-1 and Placental-Like Growth Factor Levels Are Associated With Development and Mortality Risk in Heart Failure

BACKGROUND

Vascular endothelial dysfunction may play an important role in the progression of heart failure (HF). We hypothesize that elevated levels of vascular markers, placental-like growth factor, and soluble Fms-like tyrosine kinase-1 (sFlt-1) are associated with adverse outcomes in patients with HF. We also assessed possible triggers of sFlt-1 elevation in animal HF models.

METHODS AND RESULTS

We measured plasma placental-like growth factor and sFlt-1 in 791 HF patients undergoing elective coronary angiogram. Median (interquartile range) placental-like growth factor and sFlt-1 levels were 24 (20-29) and 382 (277-953) pg/mL, respectively. After 5 years of follow-up, and after using receiver operator characteristic curves to determine optimal cutoffs, high levels of sFlt-1 (≥ 280 pg/mL; adjusted hazard ratio, 1.47; 95% confidence interval, 1.03-2.09; P=0.035) but not placental-like growth factor (≥ 25 pg/mL; adjusted hazard ratio, 1.26; 95% confidence interval, 0.94-1.71, P=0.12) were associated with adverse cardiovascular outcomes. In addition, significant elevation of sFlt-1 levels was observed in left anterior descending artery ligation and transverse aortic constriction HF mouse models after 4 and 8 weeks of follow-up, suggesting vascular stress and ischemia as triggers for sFlt-1 elevation in HF.

CONCLUSIONS

Circulating sFlt-1 is generated as a result of myocardial injury and subsequent HF development. Elevated levels of sFlt-1 are associated with adverse outcomes in stable patients with HF.

Circulating multimarker profile of patients with symptomatic heart failure supports enhanced fibrotic degradation and decreased angiogenesis

BACKGROUND

Heart failure (HF) involves myocardial fibrosis and dysregulated angiogenesis.

OBJECTIVE

We explored whether biomarkers of fibrosis and angiogenesis correlate with HF severity.

METHODS

Biomarkers of fibrosis [procollagen types I and III (PIP and P3NP), carboxyterminal-telopeptide of type I collagen (ICTP), matrix metalloproteases (MMP2 and MMP9), tissue inhibitor of MMP1 (TIMP1)]; and angiogenesis [placental growth factor (PGF), vascular endothelial growth factor (VEGF), soluble Fms-like tyrosine kinase-1 (sFlt1)] were measured in 52 HF patients and 19 controls.

RESULTS

P3NP, ICTP, MMP2, TIMP1, PGF, and sFlt1 levels were elevated in HF, while PIP/ICTP, PGF/sFlt1, and VEGF/sFlt1 ratios were reduced. PIP/ICTP, MMP-9/TIMP1, and VEGF/sFlt1 ratios were lowest among patients with severe HF.

CONCLUSIONS

Severe HF is associated with collagen breakdown and reduced angiogenesis. A multimarker approach may guide therapeutic targeting of fibrosis and angiogenesis in HF.

Soluble Flt-1 links microvascular disease with heart failure in CKD

Chronic kidney disease (CKD) is associated with an increased risk of heart failure (HF). Elevated plasma concentrations of soluble Flt-1 (sFlt-1) have been linked to cardiovascular disease in CKD patients, but whether sFlt-1 contributes to HF in CKD is still unknown. To provide evidence that concludes a pathophysiological role of sFlt-1 in CKD-associated HF, we measured plasma sFlt-1 concentrations in 586 patients with angiographically documented coronary artery disease and renal function classified according to estimated glomerular filtration rate (eGFR). sFlt-1 concentrations correlated negatively with eGFR and were associated with signs of heart failure, based on New York Heart Association functional class and reduced left ventricular ejection fraction (LVEF), and early mortality. Additionally, rats treated with recombinant sFlt-1 showed a 15 % reduction in LVEF and a 29 % reduction in cardiac output compared with control rats. High sFlt-1 concentrations were associated with a 15 % reduction in heart capillary density (number of vessels/cardiomyocyte) and a 24 % reduction in myocardial blood volume. Electron microscopy and histological analysis revealed mitochondrial damage and interstitial fibrosis in the hearts of sFlt-1-treated, but not control rats. In 5/6-nephrectomised rats, an animal model of CKD, sFlt-1 antagonism with recombinant VEGF121 preserved heart microvasculature and significantly improved heart function. Overall, these findings suggest that a component of cardiovascular risk in CKD patients could be directly attributed to sFlt-1. Assessment of patients with CKD confirmed that sFlt-1 concentrations were inversely correlated with renal function, while studies in rats suggested that sFlt-1 may link microvascular disease with HF in CKD.

Ratio between fms-like tyrosine kinase 1 and placental growth factor in children with congenital heart disease

Serum levels of soluble fms-like tyrosine kinase 1 (sFlt-1), an antiangiogenic factor, and its binding protein, placental growth factor (PlGF), are altered in women with preeclampsia. Recently, the sFlt-1/PlGF ratio has been shown to predict acute coronary syndrome in adults. However, few reports have described the use of the sFlt-1/PlGF ratio for evaluating an abnormal hemodynamic load in children with congenital heart disease (CHD). The sFlt-1/PlGF ratio was determined in 20 children with atrial septal defects (ASD), 26 children with ventricular septal defects (VSD), 57 children with tetralogy of Fallot (ToF), 35 children who were Fontan candidates (Fontan), and 14 controls. The preoperative sFlt-1/PlGF ratios in the ASD, VSD, and Fontan were significantly higher than those in the controls and were significantly decreased after surgical repair in the ASD and VSD. In the ToF, the sFlt-1/PlGF ratio was highest after first-stage repair and second-highest after final-stage palliation compared with the preoperative levels. The sFlt-1/PlGF ratio was highest after first-stage repair and much lower after final-stage palliation in the Fontan. Furthermore, these ratios correlated with the degree of the ventricular volume overload and hypoxia. Our study clearly demonstrated that the sFlt-1/PlGF ratio increases with volume overload and persistent hypoxia after surgery with CHD. These findings may prove useful in the management of CHD in children.

Suppressed soluble Fms-like tyrosine kinase-1 production aggravates atherosclerosis in chronic kidney disease

Patients with chronic kidney disease (CKD) die of cardiovascular diseases for unknown reasons. Blood vessel formation in plaques and its relationship with plaque stability could be involved with signaling through the Flt-1 receptor and its ligands, vascular endothelial growth factor, and the closely related placental growth factor (PlGF). Flt-1 also exists as a circulating regulatory splice variant short-inhibitory form (sFlt-1) that serves as a decoy receptor, thereby inactivating PlGF. Heparin releases sFlt-1 by displacing the sFlt-1 heparin-binding site from heparin sulfate proteoglycans. Heparin could provide diagnostic inference or could also induce an antiangiogenic state. In the present study, postheparin sFlt-1 levels were lower in CKD patients than in control subjects. More importantly, sFlt-1 levels were inversely related to atherosclerosis in CKD patients, and this correlation was more robust after heparin injection, as verified by subsequent cardiovascular events. Knockout of apolipoprotein E (ApoE) and/or sFlt-1 showed that the absence of sFlt-1 worsened atherogenesis in ApoE-deficient mice. Thus, the relationship between atherosclerosis and PlGF signaling, as regulated by sFlt-1, underscores the underappreciated role of heparin in sFlt-1 release. These clinical and experimental data suggest that novel avenues into CKD-dependent atherosclerosis and its detection are warranted.

Soluble Fms-like tyrosine kinase 1 is a novel predictor of brain natriuretic peptide elevation

Soluble fms-like tyrosine kinase 1 (sFlt-1) is an endogenous inhibitor of vascular endothelial growth factor, which is involved in cardiovascular remodeling and atherosclerosis development. To examine the predictive role of sFlt-1 levels in patients with asymptomatic heart failure, we measured circulating sFlt-1 in patients with or without coronary artery disease (CAD). We analyzed 88 Japanese patients with CAD or patients at high risk for atherosclerosis and who were undergoing total risk management for cardiovascular disease prevention. Circulating sFlt-1 levels correlated with the increase in plasma brain natriuretic peptide levels (ΔBNP) from baseline to the observed levels 5 years later in CAD patients, patients with previous myocardial infarction, and men. ΔBNP levels correlated with sFlt-1 levels in the high-sFlt-1 patients with CAD (r = 0.511, P < 0.01). In all patients, end-systolic volume index (ΔESVI) increased in correlation with a decrease in left ventricular ejection fraction (ΔEF) in the long-term observation, independent of their history of myocardial infarction (ΔESVI = 2.5 mL/m(2) increase/year). Baseline level of sFlt-1 was independent of ΔESVI or ΔEF. The present 5-year observational study demonstrated that high sFlt-1 levels predicted moderate increases in BNP levels in CAD patients. Moreover, ΔBNP was correlated with ΔESVI/year in CAD patients with high-sFlt-1 levels. These data suggest that high sFlt-1 levels may be an effective biomarker to predict the progression of heart failure in patients with CAD.

Endothelial dysfunction and hypertension in obstructive sleep apnea - Is it due to intermittent hypoxia?

BACKGROUND

Obstructive sleep apnea (OSA) is a prevalent disorder causing hypertension. Endothelial dysfunction appears to underlie development of hypertension. It is not known whether hypoxia during sleep is necessarily the prerequisite process for endothelial dysfunction and hypertension in OSA. We therefore examined the relationship between endothelial-dependent vasodilatory capacity, hypoxia and circulating angiogenesis inhibitors in OSA.

METHODS AND RESULTS

We studies 95 subjects with and without OSA and hypertension. Endothelial-dependent vasodilation was assessed using brachial artery flow-mediated vasodilation method (FMD). Plasma angiogenesis inhibitors, endoglin (sEng) and fms-like tyrosine kinase-1 (sFlt-1), were measured using ELISA. The apnea-hypopnea indexes were 41 ± 5 and 48 ± 4 events/hr in normotensive OSA (N-OSA) and hypertensive OSA (H-OSA), respectively, indicating severe OSA. The sleep time spent with SaO2 < 90% (T < 90%) were 34 ± 8 and 40 ± 9 min, respectively. FMD was markedly impaired in H-OSA (8.0% ± 0.5) compared to N-OSA (13.5% ± 0.5, P < 0.0001), H-non-OSA (10.5% ± 0.8, P < 0.01), and N-non-OSA (16.1% ± 1.0, P < 0.0001). There was no correlation between T < 90% and FMD. Both OSA groups had elevated levels of sFlt-1 (62.4 ± 5.9 and 63.9 ± 4.7 pg/ml) compared to N-non-OSA (32.1 ± 6.5, P = 0.0008 and P = 0.0004, respectively) and H-non-OSA (41.2 ± 7.0, P < 0.05 and P = 0.03, respectively). In contrast, sEng was only elevated in H-OSA (4.20 ± 0.17 ng/ml) compared with N-OSA (3.64 ± 0.14, P = 0.01) and N-non-OSA (3.48 ± 0.20, P = 0.01). There was a modest but statistically significant inverse correlation between sEng and FMD in only H-OSA group (r = -0.38, P < 0.05).

CONCLUSION

These data show that patients with OSA and hypertension have marked impairment of FMD, independent of hypoxia exposure, which is associated with increased sEng.

Hypoxia-inducible factor-1 alpha in the heart: a double agent?

Hypoxia-inducible factor (HIF) is a set of transcription factors that regulate the cellular response to hypoxia. There is a great body of evidence supporting the protective role of HIF-1α in cardiovascular pathophysiology, however, newer studies are hinting at a maladaptive and deleterious role of this transcription factor that merits further investigation. There is a general agreement, however, that HIF-mediated responses appear to differ under conditions of acute and chronic oxygen deprivation. The intensity and sustainability of HIF-1α activation are major determinants of whether the responses are pathological or beneficial. HIF activation is seen to be beneficial in the setting of acute myocardial ischemia and deleterious in chronic conditions. In this review, we will focus on recent insights into the role of HIF-1α in the heart and especially in the setting of ischemic heart disease.

An elevated ratio of placental growth factor to soluble fms-like tyrosine kinase-1 predicts adverse outcomes in patients with stable coronary artery disease

OBJECTIVE

To investigate the predictive values of placental growth factor (PlGF) and its endogenous antagonist, soluble fms-like tyrosine kinase-1 (sFlt-1), for the long-term prognosis of patients with stable coronary artery disease (CAD). Both PlGF and sFlt-1 play important roles in the pathological mechanisms of atherosclerosis. We recently demonstrated that the plasma levels of these molecules are correlated with the severity of coronary atherosclerosis.

METHODS

We enrolled 464 patients with stable CAD who consecutively underwent coronary angiography. Baseline blood samples were collected from the femoral artery immediately before coronary angiography (after the administration of 20 units of heparin), and the plasma levels of PlGF and sFlt-1 were measured. A Cox proportional hazard regression analysis was performed to evaluate the relationship between these parameters and the occurrence of all-cause death (ACD) and total cardiovascular events (TCVE) during a median follow-up of 3.3 years.

RESULTS

A total of 31 ACDs and 51 TCVEs occurred. Patients with higher PlGF/sFlt-1 ratios (>4.22×10(-2)) had a significantly higher risk of both ACD and TCVE than patients with lower ratios (<4.22×10(-2)) (hazard ratio [HR]: 3.32, 95% confidence interval [CI]: 1.43 to 7.72, p=0.005, and HR: 2.23, 95% CI: 1.23 to 4.03, p=0.008, respectively). A multivariate analysis showed the PlGF/sFlt-1 ratio to be an independent predictor for ACD, but not TCVE.

CONCLUSION

The baseline PlGF/sFlt-1 ratio is an independent predictor of long-term adverse outcomes in patients with stable CAD.

Vascular endothelial growth factor (VEGF) and the VEGF soluble receptor-1 (sFlt-1) in chorionic villus tissue from Chinese women with early recurrent spontaneous abortion

This case-control study explored the relationship between early recurrent spontaneous abortion (RSA) and the expression of two genes: VEGFA, the gene encoding vascular endothelial growth factor (VEGF); and fms-related tyrosine kinase 1 (FLT1), the gene encoding the soluble VEGF receptor-1 (sFlt-1). Women experiencing RSA or undergoing induced abortions in the early stage of normal pregnancy were recruited to the study (n = 30 per group). There were no significant between-group differences in maternal age or duration of pregnancy. The levels of VEGF and sFlt-1 mRNA in chorionic villus tissue samples were examined by quanti tative reverse transcription-polymerase chain reaction. Levels of sFlt-1 and VEGF mRNA in the chorionic villus tissue of women with RSA were significantly higher than levels in the control group. This study demonstrated that there is a relationship between early RSA and VEGF and sFlt-1 levels, suggesting that over-expression of the FLT1 and VEGFA genes may be associated with the pathogenesis of RSA.

Heparin strongly induces soluble fms-like tyrosine kinase 1 release in vivo and in vitro--brief report

OBJECTIVE

Soluble fms-like tyrosine kinase 1 (sFlt1) is involved in the pathophysiology of preeclampsia and coronary artery disease. Because sFlt1 has a heparin-binding site, we investigated whether or not heparin releases sFlt1 from the extracellular matrix.

METHODS AND RESULTS

We measured sFlt1 before and after heparin administration in 135 patients undergoing coronary angiography, percutanous coronary intervention, or both. sFlt1 was increased directly after heparin administration (from 254 to 13,440 pg/mL) and returned to baseline within 10 hours. Umbilical veins and endothelial cells treated with heparin released sFlt1. Heparinase I and III also increased sFlt1. Mice treated with heparin had elevated sFlt1 serum levels. Their serum inhibited endothelial tube formation.

CONCLUSIONS

Heparin releases sFlt1 by displacing the sFlt1 heparin-binding site from heparan sulfate proteoglycans. Heparin could induce an antiangiogenic state.

The vascular marker soluble fms-like tyrosine kinase 1 is associated with disease severity and adverse outcomes in chronic heart failure

OBJECTIVES

We sought to evaluate placental growth factor (PlGF) and soluble Fms-like tyrosine kinase 1 (sFlt-1) as clinical biomarkers in chronic heart failure (HF).

BACKGROUND

Vascular remodeling is a crucial compensatory mechanism in chronic HF. The angiogenic ligand PlGF and its target receptor fms-like tyrosine kinase 1 modulate vascular growth and function, but their relevance in human HF is undefined.

METHODS

We measured plasma PlGF and sFlt-1 in 1,403 patients from the Penn Heart Failure Study, a multicenter cohort of chronic systolic HF. Subjects were followed for death, cardiac transplantation, or ventricular assist device placement over a median follow-up of 2 years.

RESULTS

The sFlt-1 was independently associated with measures of HF severity, including New York Heart Association functional class (p < 0.01) and B-type natriuretic peptide (p < 0.01). Patients in the 4th quartile of sFlt-1 (>379 pg/ml) had a 6.17-fold increased risk of adverse outcomes (p < 0.01). This association was robust, even after adjustment for the Seattle Failure Model (hazard ratio: 2.54, 95% confidence interval [CI]: 1.76 to 2.27, p < 0.01) and clinical confounders including HF etiology (hazard ratio: 1.67, 95% CI: 1.06 to 2.63, p = 0.03). Combined assessment of sFlt-1 and B-type natriuretic peptide exhibited high predictive accuracy at 1 year (area under the receiver-operator characteristic curve: 0.791, 95% CI: 0.752 to 0.831) that was greater than either marker alone (p < 0.01 and p = 0.03, respectively). In contrast, PlGF was not an independent marker of disease severity or outcomes.

CONCLUSIONS

Our findings support a role for sFlt-1 in the biology of human HF. With additional study, circulating sFlt-1 might emerge as a clinically useful biomarker to assess the influence of vascular remodeling on clinical outcomes.

Soluble fms-like tyrosine kinase-1 antibody for diagnosis purposes (WO2010075475)

BACKGROUND

The application (WO2010075475) is involved in the diagnosis of angiogenesis-dependent diseases related with the soluble FMS-like tyrosine kinase-1 (sFlt-1) biomarker.

OBJECTIVE

It aims to identify, characterize and produce antibodies raised against sFlt-1 for the diagnosis of preeclampsia as well as other cardiovascular diseases.

METHODS

The diagnostic kit is based on a double mAb sandwich assay, comprising of a capture anti-sFlt-1 mAb, grafted onto paramagnetic particles that are able to bind sFlt-1 both in bound and free forms. An acridinium conjugated anti-sFlt-1 antibody, which binds to s-Flt1 on another epitope, serves as a chemioluminescent label.

RESULTS

Using this assay, the total amount of sFlt-1 could be estimated in various biological samples.

CONCLUSION

Antibodies against the free and bound forms of sFlt-1 offer new opportunities in the diagnostics of preeclampsia and other angiogenesis-dependent disorders. Furthermore, as demonstrated in this patent, the immunoassay could be automated and is fast and reliable.

Elevated Soluble fms-Like Tyrosine Kinase-1 Levels in Acute Coronary Occlusion

Objective—

Early recognition of an acute coronary occlusion (ACO) improves clinical outcomes. Soluble fms-like tyrosine kinase-1 (sFLT1) is an endothelium-derived protein induced by hypoxia. We tested whether sFLT1 levels are elevated in ACO.

Methods and Results—

Serum sFLT1 levels were measured by enzyme-linked immunosorbent assay in patients with ST-segment elevations and angiographically confirmed ACO, unstable angina/non ST-segment elevation myocardial infarction, and 2 control groups. To further explore sFLT1 release, a mouse model of ACO and in vitro human coronary artery endothelial cell injury were used. sFLT1 levels were increased in ACO compared with unstable angina/non-ST-elevation myocardial infarction, catheterized controls, or healthy volunteers (200.7±15.5 versus 70.7±44.0 versus 10.2±4.0 versus 11.7±1.7 pg/mL respectively, P <0.001 versus ACO). At presentation, all ACO patients had elevated sFLT1 levels (>15 pg/mL, 99th percentile in controls), whereas 57% had levels of the MB isoform of creatine kinase levels >10 ng/mL ( P <0.01) and 85% had ultrasensitive troponin I levels >0.05 ng/mL ( P <0.05). Within 60 minutes after symptom onset, sFLT1 was more sensitive than the MB isoform of creatine kinase or ultrasensitive troponin I for ACO (100% versus 20% versus 20% respectively; P ≤0.01 for each). Within 60 minutes of ACO in mice, sFLT1 levels were elevated. Hypoxia and thrombin increased sFLT1 levels within 15 minutes in human coronary artery endothelial cells.

Conclusion—

sFLT1 levels may be an early indicator of endothelial hypoxia in ACO.