Galectin-3 and Blood Group: Binding Properties, Effects on Plasma Levels, and Consequences for Prognostic Performance.

Previous studies have reported an association between ABO type blood group and cardiovascular (CV) events and outcomes. The precise mechanisms underpinning this striking observation remain unknown, although differences in von Willebrand factor (VWF) plasma levels have been proposed as an explanation. Recently, galectin-3 was identified as an endogenous ligand of VWF and red blood cells (RBCs) and, therefore, we aimed to explore the role of galectin-3 in different blood groups. Two in vitro assays were used to assess the binding capacity of galectin-3 to RBCs and VWF in different blood groups. Additionally, plasma levels of galectin-3 were measured in different blood groups in the Ludwigshafen Risk and Cardiovascular Health (LURIC) study (2571 patients hospitalized for coronary angiography) and validated in a community-based cohort of the Prevention of Renal and Vascular End-stage Disease (PREVEND) study (3552 participants). To determine the prognostic value of galectin-3 in different blood groups, logistic regression and cox regression models were used with all-cause mortality as the primary outcome. First, we demonstrated that galectin-3 has a higher binding capacity for RBCs and VWF in non-O blood groups, compared to blood group O. Additionally, LURIC patients with non-O blood groups had substantially lower plasma levels of galectin-3 (15.0, 14.9, and 14.0 µg/L in blood groups A, B, and AB, respectively, compared to 17.1 µg/L in blood group O, p < 0.0001). Finally, the independent prognostic value of galectin-3 for all-cause mortality showed a non-significant trend towards higher mortality in non-O blood groups. Although plasma galectin-3 levels are lower in non-O blood groups, the prognostic value of galectin-3 is also present in subjects with a non-O blood group. We conclude that physical interaction between galectin-3 and blood group epitopes may modulate galectin-3, which may affect its performance as a biomarker and its biological activity.

Pharmacological inhibition of galectin-3 protects against hypertensive nephropathy.

Galectin-3 activation is involved in the pathogenesis of renal damage and fibrogenesis. Limited data are available to suggest that galectin-3-targeted intervention is a potential therapeutic candidate for the prevention of chronic kidney disease. Homozygous TGR(mREN)27 (REN2) rats develop severe high blood pressure (BP) and hypertensive end-organ damage, including nephropathy and heart failure. Male REN2 rats were treated with N-acetyllactosamine [galectin-3 inhibitor (Gal3i)] for 6 wk; untreated REN2 and Sprague-Dawley rats served as controls. We measured cardiac function with echocardiogram and invasive hemodynamics before termination. BP and proteinuria were measured at baseline and at 3 and 6 wk. Plasma creatinine was determined at 6 wk. Renal damage was assessed for focal glomerular sclerosis, glomerular desmin expression, glomerular and interstitial macrophages, kidney injury molecule-1 expression, and α-smooth muscle actin expression. Inflammatory cytokines and extracellular matrix proteinases were quantified by quantitative real-time PCR. Systolic BP was higher in control REN2 rats, with no effect of Gal3i treatment. Plasma creatinine and proteinuria were significantly increased in control REN2 rats; Gal3i treatment reduced both. Renal damage (focal glomerular sclerosis, desmin, interstitial macrophages, kidney injury molecule-1, α-smooth muscle actin, collagen type I, and collagen type III) was also improved by Gal3i. All inflammatory markers (CD68, IL-68, galectin-3, and monocyte chemoattractant protein-1) were elevated in control REN2 rats and attenuated by Gal3i. Markers of extracellular matrix turnover were marginally altered in untreated REN2 rats compared with Sprague-Dawley rats. In conclusion, galectin-3 inhibition attenuated hypertensive nephropathy, as indicated by reduced proteinuria, improved renal function, and decreased renal damage. Drugs binding to galectin-3 may be therapeutic candidates for the prevention of chronic kidney disease.

Galectin-3: a modifiable risk factor in heart failure.

Myocardial galectin-3 is upregulated upon cardiac stressors such as angiotensin II and pressure overload leading to cardiac remodeling and heart failure. The expression level of galectin-3 mirrors the progression and severity of heart failure and therefore, galectin-3 is being used as a biomarker for heart failure. However, as galectin-3 is causally involved in pathological myocardial fibrosis it has been suggested that galectin-3 also actively contributes to heart failure development. In this review we discuss how galectin-3 could be a target for therapy in heart failure. Currently, attempts are being made to target or inhibit galectin-3 using natural or pharmaceutical inhibitors with the aim to ameliorate heart failure. Available experimental evidence suggests that galectin-3 inhibition indeed may represent a novel tool to treat heart failure. A strong interaction with aldosterone, another strong pro-fibrotic factor, has been described. Clinical studies are needed to prove if galectin-3 may be used to install specific treatment regimens.

Biomarkers for risk prediction in acute decompensated heart failure.

Risk prediction in patients admitted with acute decompensated heart failure (ADHF) remains a challenge. Biomarkers may improve risk prediction, which in turn may help to better inform patients regarding short-term and long-term prognosis, therapy and care. Most data on biomarkers have been derived from patient cohorts with chronic heart failure. In ADHF, currently, risk tools largely rely on common clinical and biochemical parameters. However, ADHF is not a single disease. It presents in various manners and different etiologies may underlie ADHF, which are reflected by different biomarkers. In the last decade, many studies have reported the prognostic value of these biomarkers. These studies have attempted to describe a value for statistical modeling, e.g., reclassification indices, in an effort to report incremental value over a clinical model or the "gold standard". However, the overall incremental predictive value of biomarkers has been modest compared to already existing clinical models. Natriuretic peptides, e.g., (NTpro-)BNP, are the benchmark, but head-to-head comparisons show that there are novel biomarkers with comparable prognostic value. Multimarker strategies may provide superior risk stratification. Future studies should elucidate cost-effectiveness of single or combined biomarker testing. The purpose of this review was to provide an update on current biomarkers and to identify new promising biomarkers than can be used in prognostication of acute heart failure.

Variability of biomarkers in patients with chronic heart failure and healthy controls.

AIMS: Biomarkers can be used for diagnosis, risk stratification, or management of patients with heart failure (HF). Knowledge about the biological variation is needed for proper interpretation of serial measurements. Therefore, we aimed to determine and compare the biological variation of a large panel of biomarkers in healthy subjects and in patients with chronic HF. METHODS AND RESULTS: The biological variability of established biomarkers [NT-proBNP and high-sensitivity troponin T (hsTnT)], novel biomarkers [galectin-3, suppression of tumorigenicity 2 (ST2), and growth differentiation factor 15 (GDF-15)], and renal/neurohormonal biomarkers (aldosterone, phosphate, parathyroid hormone, plasma renin concentration, and creatinine) was determined in 28 healthy subjects and 83 HF patients, over a period of 4 months and 6 weeks, respectively. The analytical (CVa ), intraindividual (CVi ), and interindividual (CVg ) variations were calculated, as well as the reference change value (RCV), which reflects the percentage of change that may indicate a 'relevant' change. All crude biomarker levels were significantly increased or decreased in HF patients compared with controls (all P < 0.01). Variation indices were comparable in healthy individuals and HF patients. CVi was not influenced by the individual levels of the biomarker itself. NT-proBNP and GDF-15 had relatively high CVi (21.8% and 16.6%) and RCV (61.7% and 64.3%), whereas ST2 (CVi , 15.0; RCV, 42.9%), hsTnT (CVi , 11.1; RCV, 31.4%), and galectin-3 (CVi , 8.1; RCV, 25.0%) had lower indices of variation. CONCLUSION: Biological variation indices are comparable between healthy subjects and HF patients for a broad spectrum of biomarkers. NT-proBNP and GDF-15 have substantial variation, with lower variation for ST2, hsTnT, and galectin-3. These data are instrumental in proper interpretation of biomarker levels in HF patients.

Rodent heart failure models do not reflect the human circulating microRNA signature in heart failure.

INTRODUCTION: We recently identified a set of plasma microRNAs (miRNAs) that are downregulated in patients with heart failure in comparison with control subjects. To better understand their meaning and function, we sought to validate these circulating miRNAs in 3 different well-established rat and mouse heart failure models, and correlated the miRNAs to parameters of cardiac function. METHODS: The previously identified let-7i-5p, miR-16-5p, miR-18a-5p, miR-26b-5p, miR-27a-3p, miR-30e-5p, miR-199a-3p, miR-223-3p, miR-423-3p, miR-423-5p and miR-652-3p were measured by means of quantitative real time polymerase chain reaction (qRT-PCR) in plasma samples of 8 homozygous TGR(mREN2)27 (Ren2) transgenic rats and 8 (control) Sprague-Dawley rats, 6 mice with angiotensin II-induced heart failure (AngII) and 6 control mice, and 8 mice with ischemic heart failure and 6 controls. Circulating miRNA levels were compared between the heart failure animals and healthy controls. RESULTS: Ren2 rats, AngII mice and mice with ischemic heart failure showed clear signs of heart failure, exemplified by increased left ventricular and lung weights, elevated end-diastolic left ventricular pressures, increased expression of cardiac stress markers and reduced left ventricular ejection fraction. All miRNAs were detectable in plasma from rats and mice. No significant differences were observed between the circulating miRNAs in heart failure animals when compared to the healthy controls (all P>0.05) and no robust associations with cardiac function could be found. CONCLUSIONS: The previous observation that miRNAs circulate in lower levels in human patients with heart failure could not be validated in well-established rat and mouse heart failure models. These results question the translation of data on human circulating miRNA levels to experimental models, and vice versa the validity of experimental miRNA data for human heart failure.

ST2 and Galectin-3: Ready for Prime Time?

ST2 and galectin-3 are emerging biomarkers in the field of heart failure and have been extensively studied, and that whether they provide additional prognostic value on top of the clinical models and the gold standard in HF, (NT-pro)BNP. Our aim was to provide a comprehensive review of these emerging HF-related biomarkers in chronic, acute and incident heart failure. Regardless of the type of heart failure, both biomarkers seem to have an additional effect on top of the clinical model including natriuretic peptides. Strategies that combine multiple biomarkers may ultimately prove to be beneficial in the guidance of HF therapy in the future. However, additional prognostic value appears to be limited, and what we need is to prospectively test the consistent observations, which then might lead to the implementation of ST2 and galectin-3 in heart failure algorithms.

Galectin-3 and sST2 in prediction of left ventricular ejection fraction after myocardial infarction.

BACKGROUND: Fibrosis is a pivotal event in infarct repair and progressive remodeling after myocardial infarction (MI). Biomarkers may be used to monitor fibrosis, and therefore we evaluated the predictive value of galectin-3 and sST2 for cardiac remodeling after MI. METHODS: Plasma galectin-3 and sST2 were measured in patients admitted with primary percutaneous coronary intervention (PCI) for acute MI, at baseline and at 4months. Left ventricular ejection fraction (LVEF) and infarct size were measured after 4months with cardiac MRI (CMR). RESULTS: In total, 247 patients had blood samples and CMR data available (mean age 57.7±11.6years; 79.8% male). Increased baseline galectin-3 (≥17.8ng/mL) identified patients with lower LVEF (50.3% (±9.1) vs. non-elevated galectin-3 55.0% (±8.0); P<0.001), and larger infarct size (13.8g. (±12.9) vs. 8.6g. (±8.7); P=0.002) after 4months. Elevated sST2 (≥35.0ng/mL) did not predict decreased LVEF or larger infarct size. Furthermore we showed that at baseline, galectin-3 was an independent predictor for LVEF (ß=-0.18; P=0.005) and infarct size (ß=0.18; P=0.004). We repeated the analyses using median values of galectin-3 (13.4ng/mL) and sST2 (30.3ng/mL) as a cut point, and this validated our results. CONCLUSION: The fibrosis biomarker galectin-3, but not sST2, taken immediately after MI, predicts LVEF and infarct size after 4months. We hypothesize that galectin-3 may play a role in the pathophysiology of cardiac remodeling after acute MI.

Determinants of temporal changes in galectin-3 level in the general population: Data of PREVEND.

BACKGROUND: High baseline galectin-3 levels are associated with increased risk for adverse cardiovascular outcomes in the general population, but determinants of changes in galectin-3 levels over time have not been established. Therefore, we aimed to identify determinants of (temporal) change in galectin-3 levels. METHODS: Galectin-3 plasma levels were measured in a large community based cohort (PREVEND study) at 3 different time points: at baseline, after ~4 and ~9years. The association of baseline clinical and biochemical factors and (temporal) changes in galectin-3 level was assessed using multivariable mixed-effects regression modeling. RESULTS: In 4355 subjects, galectin-3 plasma levels were available at all time points (mean age: 48±12years; 50% female). Median galectin-3 level at baseline was 10.7 [8.9-12.7] ng/mL which gradually increased to 11.5 [9.4-14.3] ng/mL after ~9years. Using mixed-effects regression modeling, we first validated as independent determinants of baseline circulating galectin-3: eGFR (chi square (χ(2)):210.27, p<0.0001), gender (χ(2):43.85; p<0.0001), BMI (χ(2):19.68, p=0.0001), NT-proBNP (χ(2):18.76, p=0.0001) and serum (total) cholesterol (χ(2):8.63, p=0.01). Furthermore, we identified urinary albumin excretion (χ(2):34.03, p-value: <0.0001) and systolic blood pressure (χ(2):16.81, p=0.002) as independent determinants of temporal changes of galectin-3. CONCLUSIONS: In the general population, urinary albumin excretion >30mg/24h and systolic blood pressure >170mmHg were identified as significant determinants of dynamic increases in galectin-3 levels over time. These results implicate that treatment of high blood pressure might be effective to prevent increasing galectin-3 levels and its associated conditions.

Serial galectin-3 and future cardiovascular disease in the general population.

BACKGROUND: Lifetime risk for cardiovascular (CV) disease is high but predicting incident events on an individual level remains difficult. Single measurements of galectin-3, a marker of tissue fibrosis, predict mortality and new-onset heart failure (HF). Persistently elevated levels may indicate a clinically silent disease process. OBJECTIVES: Our aim was to establish the value of serial galectin-3 measurements to predict CV outcomes in the general population. METHODS: Plasma galectin-3 was measured in the Prevention of REnal and Vascular ENd-stage Disease (PREVEND) study at baseline and after ∼4 years. Changes in serial galectin-3 were expressed as categorical changes or absolute change from baseline and were related to subsequent outcome. RESULTS: Serial galectin-3 was measured in 5958 subjects (mean age 49±12 years; 49% female). The median duration of follow-up was 8.3 years. Persistently elevated galectin-3 (defined as highest quartile at baseline and highest quartile during visit 2, n=757 subjects) was associated with a higher risk for new-onset HF, CV mortality, all-cause mortality, new-onset atrial fibrillation and CV events, compared with subjects with non-persistently elevated galectin-3. After multivariable adjustments for baseline characteristics, serial galectin-3 remained an independent predictor of new-onset HF (HR 1.85 (1.10-3.13); p=0.02) but not for other outcomes. Serial measurements provided more accurate prognostic value to predict new-onset HF, compared with a single baseline measurement (Harrell's C: 0.72 (0.68-0.75) vs 0.68 (0.65-0.72); p=0.002, respectively) with significant net reclassification. CONCLUSIONS: Persistently elevated galectin-3 predicts new-onset HF after adjustment for covariates, and serial measurements provide more accurate prognostic information compared with single determination of galectin-3. This may help to identify individuals who are at risk for incident HF and might provide a measure to monitor interventions.

Galectin-3 and post-myocardial infarction cardiac remodeling.

This review summarizes the current literature regarding the involvement and the putative role(s) of galectin-3 in post-myocardial infarction cardiac remodeling. Post-myocardial infarction remodeling is characterized by acute loss of myocardium, which leads to structural and biomechanical changes in order to preserve cardiac function. A hallmark herein is fibrosis formation, both in the early and late phase following acute myocardial infarction. Galectin-3, a ß-galactoside-binding lectin, which is a shared factor in fibrosis formation in multiple organs, has an established role in cardiac fibrosis in the setting of pressure overload, neuro-endocrine activation and hypertension, but its role in post- myocardial infarction remodeling has received less attention. However, accumulative experimental studies have shown that myocardial galectin-3 expression is upregulated after myocardial infarction, both on mRNA and protein level. This already occurs shortly after myocardial infarction in the infarcted and border zone area, and also at a later stage in the spared myocardium, contributing to tissue repair and fibrosis. This is associated with typical aspects of fibrosis formation, such as apposition of matricellular proteins and increased factors of collagen turnover. Interestingly, myocardial fibrosis in experimental post-myocardial infarction cardiac remodeling could be attenuated by galectin-3 inhibition. In clinical studies, circulating galectin-3 levels have been shown to identify patients at risk for new-onset heart failure and atrial fibrillation. Circulating galectin-3 levels also predict progressive left ventricular dilatation after myocardial infarction. From literature we conclude that galectin-3 is an active player in cardiac remodeling after myocardial infarction. Future studies should focus on the dynamics of galectin-3 activation after myocardial infarction, and study the possibilities to target galectin-3.

The ARCHITECT galectin-3 assay: comparison with other automated and manual assays for the measurement of circulating galectin-3 levels in heart failure.

Heart failure (HF) is a common disease and affects millions of patients worldwide. Diagnosis, risk assessment and treatment of HF are difficult and therefore there is a need for additional tools to improve clinical performance. Biomarkers may be helpful in this respect. Galectin-3 is a relatively new biomarker that has been shown to have strong associations with the development of HF. Galectin-3 plays a role in inflammation and fibrosis, which are key elements in the pathophysiology of HF. Circulating plasma or serum galectin-3 levels have strong associations with the severity of HF and may be used to prognosticate or risk-stratify HF patients. Currently, there are several commercially available assays that can measure circulating galectin-3. This article describes the role galectin-3 plays in HF and its prognostic consequences. We will summarize the technical specifications of various manual and automated galectin-3 assays, which may help in HF management.

Renal handling of galectin-3 in the general population, chronic heart failure, and hemodialysis.

BACKGROUND: Galectin-3 is a biomarker for prognostication and risk stratification of patients with heart failure (HF). It has been suggested that renal function strongly relates to galectin-3 levels. We aimed to describe galectin-3 renal handling in HF. METHODS AND RESULTS: In Sprague-Dawley rats, we infused galectin-3 and studied distribution and renal clearance. Furthermore, galectin-3 was measured in urine and plasma of healthy controls, HF patients and hemodialysis patients. To mimic the human situation, we measured galectin-3 before and after the artificial kidney. Infusion in rats resulted in a clear increase in plasma and urine galectin-3. Plasma galectin-3 in HF patients (n=101; mean age 64 years; 93% male) was significantly higher compared to control subjects (n=20; mean age 58 years; 75% male) (16.6 ng/mL versus 9.7 ng/mL, P<0.001), while urinary galectin-3 in HF patients was comparable (28.1 ng/mL versus 35.1 ng/mL, P=0.830). The calculated galectin-3 excretion rate was lower in HF patient (2.3 mL/min [1.5 to 3.4] versus 3.9 mL/min [2.3 to 6.4] in control subjects; P=0.005). This corresponded with a significantly lower fractional excretion of galectin-3 in HF patients (2.4% [1.7 to 3.7] versus 3.0% [1.9 to 5.5]; P=0.018). These differences, however, were no longer significant after correction for age, gender, diabetes, and smoking. HF patients who received diuretics (49%) showed significantly higher aldosterone and galectin-3 levels. Hemodialysis patients (n=105; mean age 63 years; 65% male), without urinary galectin-3 excretion, had strongly increased median plasma galectin-3 levels (70.6 ng/mL). CONCLUSIONS: In this small cross-sectional study, we report that urine levels of galectin-3 are not increased in HF patients, despite substantially increased plasma galectin-3 levels. The impaired renal handling of galectin-3 in patients with HF may explain the described relation between renal function and galectin-3 and may account for the elevated plasma galectin-3 in HF.

Prognostic value of changes in galectin-3 levels over time in patients with heart failure: data from CORONA and COACH.

BACKGROUND: In several cross-sectional analyses, circulating baseline levels of galectin-3, a protein involved in myocardial fibrosis and remodeling, have been associated with increased risk for morbidity and mortality in patients with heart failure (HF). The importance and clinical use of repeated measurements of galectin-3 have not yet been reported. METHODS AND RESULTS: Plasma galectin-3 was measured at baseline and at 3 months in patients enrolled in the Controlled Rosuvastatin Multinational Trial in Heart Failure (CORONA) trial (n=1329), and at baseline and at 6 months in patients enrolled in the Coordinating Study Evaluating Outcomes of Advising and Counseling Failure (COACH) trial (n=324). Patient results were analyzed by categorical and percentage changes in galectin-3 level. A threshold value of 17.8 ng/mL or 15% change from baseline was used to categorize patients. Increasing galectin-3 levels over time, from a low to high galectin-3 category, were associated with significantly more HF hospitalization and mortality compared with stable or decreasing galectin-3 levels (hazard ratio in CORONA, 1.60; 95% confidence interval, 1.13-2.25; P=0.007; hazard ratio in COACH, 2.38; 95% confidence interval, 1.02-5.55; P=0.046). In addition, patients whose galectin-3 increased by >15% between measurements had a 50% higher relative hazard of adverse event than those whose galectin-3 stayed within ±15% of the baseline value, independent of age, sex, diabetes mellitus, left ventricular ejection fraction, renal function, medication (ß-blocker, angiotensin converting enzyme inhibitor, and angiotensin receptor blocker), and N-terminal probrain natriuretic peptide (hazard ratio in CORONA, 1.50; 95% confidence interval, 1.17-1.92; P=0.001). The impact of changing galectin-3 levels on other secondary end points was comparable. CONCLUSIONS: In 2 large cohorts of patients with chronic and acute decompensated HF, repeated measurements of galectin-3 level provided important and significant prognostic value in identifying patients with HF at elevated risk for subsequent HF morbidity and mortality.