Increased Plasma Neutrophil Gelatinase-Associated Lipocalin Levels Predict Mortality in Elderly Patients with Chronic Heart Failure

Interrelationships among metabolic syndrome, bone-derived cytokines, and the most common metabolic syndrome-related diseases negatively affecting bone quality

Metabolic syndrome (MetS), as a set of medical conditions including hyperglycemia, hypertension, abdominal obesity, and dyslipidemia, represents a highly prevalent disease cluster worldwide. The individual components of MetS together increase the risk of MetS-related disorders. Recent research has demonstrated that bone, as an endocrine organ, releases several systemic cytokines (osteokines), including fibroblast growth factor 23 (FGF23), lipocalin 2 (LCN2), and sclerostin (SCL). This review not only summarizes current knowledge about MetS, osteokines and the most common MetS-related diseases with a detrimental impact on bone quality (type 2 diabetes mellitus: T2DM; cardiovascular diseases: CVDs; osteoporosis: OP), but also provides new interpretations of the relationships between osteokines and individual components of MetS, as well as between osteokines and MetS-related diseases mentioned above. In this context, particular emphasis was given on available clinical studies. According to the latest knowledge, FGF23 may become a useful biomarker for obesity, T2DM, and CVDs, as FGF23 levels were increased in patients suffering from these diseases. LCN2 could serve as an indicator of obesity, dyslipidemia, T2DM, and CVDs. The levels of LCN2 positively correlated with obesity indicators, triglycerides, and negatively correlated with high-density lipoprotein (HDL) cholesterol. Furthermore, subjects with T2DM and CVDs had higher LCN2 levels. SCL may act as a potential biomarker predicting the incidence of MetS including all its components, T2DM, CVDs, and OP. Elevated SCL levels were noted in individuals with T2DM, CVDs and reduced in patients with OP. The aforementioned bone-derived cytokines have the potential to serve as promising predictors and prospective treatment targets for MetS and MetS-related diseases negatively affecting bone quality.

The Review of Current Knowledge on Neutrophil Gelatinase-Associated Lipocalin (NGAL)

Neutrophil gelatinase-associated lipocalin (NGAL) is a 25-kDa protein that is secreted mostly by immune cells such as neutrophils, macrophages, and dendritic cells. Its production is stimulated in response to inflammation. The concentrations of NGAL can be measured in plasma, urine, and biological fluids such as peritoneal effluent. NGAL is known mainly as a biomarker of acute kidney injury and is released after tubular damage and during renal regeneration processes. NGAL is also elevated in chronic kidney disease and dialysis patients. It may play a role as a predictor of the progression of renal function decreases with complications and mortality due to kidney failure. NGAL is also useful in the diagnostic processes of cardiovascular diseases. It is highly expressed in injured heart tissue and atherosclerostic plaque; its serum concentrations correlate with the severity of heart failure and coronary artery disease. NGAL increases inflammatory states and its levels rise in arterial hypertension, obesity, diabetes, and metabolic complications such as insulin resistance, and is also involved in carcinogenesis. In this review, we present the current knowledge on NGAL and its involvement in different pathologies, especially its role in renal and cardiovascular diseases.

The role of serial cardiac biomarkers in prognostication and risk prediction of chronic heart failure: additional scientific insights with hemodynamic feedback

INTRODUCTION

Heart failure (HF) is considered as a chronic long-term and lethal disease and will continue to be a major public health problem. Studying (circulating) biomarkers is a promising field of research and could be the first step toward HF tailored prognostic strategies as well as understanding the response to HF drugs in CHF patients.

AREAS COVERED

In literature, there has been considerable research on elevated biomarker levels that are related to a poor prognosis for HF. Since biomarker levels change over time, it is important to study serial (repeated) biomarker measurements which may help us better understand the dynamic course of HF illness. However, the majority of research focuses predominantly on baseline values of biomarkers. Additionally, remote monitoring devices, like sensors, can be used to link hemodynamic information to freshen biomarker data in order to further ameliorate the management of HF.

EXPERT OPINION

Novel biomarkers and additional scientific insights with hemodynamic feedback strongly aid in the prognostication and risk prediction of chronic HF.

Renal Assessment in Acute Cardiorenal Syndrome

Cardiorenal syndrome (CRS) is a complex, heterogeneous spectrum of symptoms that has kept cardiologists awake for decades. The heart failure (HF) population being burdened with multimorbidity poses diagnostic and therapeutic challenges even for experienced clinicians. Adding deteriorated renal function to the equation, which is one of the strongest predictors of adverse outcome, we measure ourselves against possibly the biggest problem in modern cardiology. With the rapid development of new renal assessment methods, we can treat CRS more effectively than ever. The presented review focuses on explaining the pathophysiology, recent advances and current practices of monitoring renal function in patients with acute CRS. Understanding the dynamic interaction between the heart and the kidney may improve patient care and support the selection of an effective and nephroprotective treatment strategy.

Neutrophil Gelatinase-Associated Lipocalin (NGAL) in kidney injury- A systematic review

BACKGROUND

Neutrophil Gelatinase Associated Lipocalin (NGAL) is a secretory protein of neutrophils that can be found both in plasma and urine. Previous works have demonstrated a valuable marker for the early detection of acute kidney injury. In this systematic review, we aimed to assess whether NGAL could be helpful in the diagnosis and prognosis of systemic diseases with kidney involvement.

METHODS

MEDLINE, PubMed, and EMBASE databases were searched for NGAL, described as a human biomarker for diseases (total: 1690). Specifically, included studies describing the use of NGAL for determining kidney injury outcomes and other conditions associated with kidney dysfunction, including cardiovascular diseases, cardiac surgery, and critically ill systemic disorders.

RESULTS

A total of 24 validated studies were included in the systemic review after applying the exclusion criteria. In all these studies, NGAL appeared to have a predictive value irrespective of age, from newborn to 78 years. The results indicate that NGAL levels can accurately predict the outcome and severity of acute kidney injury occur in several disease processes, including contrast-induced AKI during cardiac surgery, kidney transplant rejection, chronic heart failure, and systemic inflammation in critically ill patients, even though the significance of NGAL is highly variable across studies. Very high plasma NGAL levels were observed in the patients before the acute rejection of the kidney, indicating the prognostic potential of the NGAL. Specifically, the assays conducted before 72 hrs provided a significant predictive value.

CONCLUSION

Urinary and serum NGAL appears to be an independent predictor of not only kidney complications but also cardiovascular and liver-related diseases. The kidney is also involved in pathogenesis.

Lipocalin-2 in neutrophils induces ferroptosis in septic cardiac dysfunction via increasing labile iron pool of cardiomyocytes

Cardiac dysfunction is a common complication of sepsis with high mortality. The present study was designed to identify the effect of neutrophil-derived lipocalin-2 (LCN2) in septic cardiac dysfunction (SCD) and its potential mechanism. Wild-type (WT) and LCN2-knockout (LCN2 KO) mice were peritoneally injected with lipopolysaccharide (LPS) to induce SCD. The cardiac function was assessed 12 h after LPS injection by echocardiography. Cardiac tissue was harvested for the evaluation of malonaldehyde (MDA) and prostaglandin E synthase 2 (PTGS2) mRNA levels. LPS induced ferroptosis and SCD in mice. LCN2 deficiency attenuated cardiac injury post-LPS administration. In vitro, LCN2 expression in neutrophils increased in response to LPS. Ferroptosis of cardiomyocytes induced by conditioned medium (CM) from LPS-induced neutrophils of WT mice could be attenuated in CM from LPS-induced neutrophils of LCN2 KO mice. Exogenous LCN2 induced H9C2 cell ferroptosis via increasing labile iron pool (LIP). In conclusion, our results showed that LCN2 deficiency prevented heart dysfunction and ferroptosis in SCD mice and suggested that neutrophil-derived LCN2 might be a promising therapeutic target for SCD.

Circulating Biomarkers for Cardiovascular Disease Risk Prediction in Patients With Cardiovascular Disease

Cardiovascular disease (CVD) is the leading cause of death globally. Risk assessment is crucial for identifying at-risk individuals who require immediate attention as well as to guide the intensity of medical therapy to reduce subsequent risk of CVD. In the past decade, many risk prediction models have been proposed to estimate the risk of developing CVD. However, in patients with a history of CVD, the current models that based on traditional risk factors provide limited power in predicting recurrent cardiovascular events. Several biomarkers from different pathophysiological pathways have been identified to predict cardiovascular events, and the incorporation of biomarkers into risk assessment may contribute to enhance risk stratification in secondary prevention. This review focuses on biomarkers related to cardiovascular and metabolic diseases, including B-type natriuretic peptide, high-sensitivity cardiac troponin I, adiponectin, adipocyte fatty acid-binding protein, heart-type fatty acid-binding protein, lipocalin-2, fibroblast growth factor 19 and 21, retinol-binding protein 4, plasminogen activator inhibitor-1, 25-hydroxyvitamin D, and proprotein convertase subtilisin/kexin type 9, and discusses the potential utility of these biomarkers in cardiovascular risk prediction among patients with CVD. Many of these biomarkers have shown promise in improving risk prediction of CVD. Further research is needed to assess the validity of biomarker and whether the strategy for incorporating biomarker into clinical practice may help to optimize decision-making and therapeutic management.

Novel molecular markers of cardiovascular disease risk in type 2 diabetes mellitus

Diabetes represents the leading risk factor for the development of cardiovascular disease (CVD). Chronic hyperglycemia and/or acute post-prandial changes in blood glucose determine an increase in reactive oxygen species (ROS), which play a fundamental role in endothelial dysfunction and in the nuclear transport of pro-atherogenic transcription factors that activate the "inflammasome". In addition, the glycemic alteration favors the formation and stabilization of atherosclerotic plaque through the mechanism of non-enzymatic glycation of different molecules, with the establishment of the so-called "advanced glycosylation end products" (AGE). Laboratory information provided by the level of biomarkers could make a quantitative and qualitative contribution to the clinical process of screening, prediction, prevention, diagnosis, prognosis and monitoring of cardiovascular (CV) risk linked to diabetes. This review describes the importance of specific biomarkers, with particular focus on novel ones, for stratifying and management of diabetes CV risk.

Silencing of lipocalin-2 improves cardiomyocyte viability under iron overload conditions via decreasing mitochondrial dysfunction and apoptosis

This study aimed to investigate the mechanistic roles of LCN-2 and LCN-2 receptors (LCN-2R) as iron transporters in cardiomyocytes under iron overload condition. H9c2 cardiomyocytes were treated with either LCN-2 small interfering RNA (siRNA) or LCN-2R siRNA or L-type or T-type calcium channel (LTCC or TTCC) blockers, or iron chelator deferiprone (DFP). After the treatments, the cells were exposed to Fe³⁺ or Fe²⁺ , after that biological parameters were determined. Silencing of lipocalin-2 or its receptor improved cardiomyocyte viability via decreasing iron uptake, mitochondrial fission, mitophagy and cleaved caspase-3 only in the Fe³⁺ overload condition. In contrast, treatments with LTCC blocker and TTCC blocker showed beneficial effects on those parameters only in conditions of Fe²⁺ overload. Treatment with DFP has been shown beneficial effects both in Fe²⁺ and Fe³⁺ overload condition. All of these findings suggested that LTCC and TTCC play crucial roles in the Fe²⁺ uptake, whereas LCN-2 and LCN-2R were essential for Fe³⁺ uptake into the cardiomyocytes under iron overload conditions.

The Prognostic Utility of Plasma NGAL Levels in ST Segment Elevation in Myocardial Infarction Patients

Introduction

Plasma neutrophil gelatinase-associated lipocalin (NGAL) levels in acute myocardial infarction (AMI) patients are markedly higher. In addition, plasma NGAL levels were increased in patients with acute and chronic heart failure as a complication of myocardial infarction. In this study, we investigated whether there is a difference between the prognostic use of plasma NGAL levels in ST-elevation myocardial infarction (STEMI) patients with preserved and reduced left ventricular ejection fraction (LVEF).

Methods

235 consecutive STEMI patients were enrolled in the study. Patients were divided into groups according to LVEF. Plasma NGAL, troponin I, creatine kinase MB (CKMB), and C-reactive protein (CRP) were measured. Finally, the study population examined with 34 reduced LVEF and 34 preserved LVEF consisted of a total of 68 patients (12 females; mean age, 61.5 ± 14.7). All patients were followed up prospectively for 6 months. This study group was divided into two subgroups as the patients who died (n = 14) and survived (n = 34), and plasma NGAL levels of the groups were compared.

Results

The median of NGAL was 190.08 ng/ml. Age, troponin I, CKMB, CRP, glomerular filtration rate, and creatinine were higher in reduced LVEF groups. Plasma NGAL levels were also higher in reduced LVEF than in preserved LVEF, but statistically not significant (p=0.07). Plasma NGAL levels were significantly higher in death patients than in survived patients (p < 0.001). In ROC curve analysis, the level to detect isolated cardiovascular mortality with a sensitivity of 86% and a specificity of 77% was 190 ng/mL for NGAL.

Conclusion

Plasma NGAL levels can be used to predict cardiovascular mortality in STEMI patients.

Cardiac biomarkers of heart failure in chronic kidney disease

Heart failure remains a continuing threat to patients with chronic kidney disease (CKD). Although various heart failure biomarkers have been applied for early detection, diagnosis and prognosis in CKD, these are easily affected by renal insufficiency thus limiting use in these patients. In this review, the major four groups of heart failure biomarkers are explored. These include those associated with: myocardial stretch, ie, brain natriuretic peptide (BNP), N-terminal pro-BNP (NT-proBNP) and mid-regional proatrial natriuretic peptide (MR-proANP); myocyte injury, ie, high-sensitivity troponin T (hsTnT), heart-type fatty acid-binding protein (H-FABP); fibrosis, matrix remodelling and inflammation, ie, soluble growth stimulating gene 2 (sST2), galectin-3 (Gal-3), growth differentiation factor-15 (GDF-15); and renal function, ie, neutrophil gelatinase-associated lipocalin (NGAL) kidney injury molecule-1 (KIM-1), cystatin C (CysC), urinary sodium and urinary albumin. This review highlights classic heart failure biomarkers with critical values adjusted to glomerular filtration rate, summarizes research progress of new heart failure biomarkers and future research directions. Because diagnostic and prognostic usefulness of a single time point biomarker is limited, biomarkers should be combined and monitored at multiple times for optimal clinical impact.

Urine biomarkers of chronic kidney damage and renal functional decline in childhood-onset systemic lupus erythematosus

OBJECTIVES

To delineate urine biomarkers that reflect kidney structural damage and predict renal functional decline in pediatric lupus nephritis (LN).

METHODS

In this prospective study, we evaluated kidney biopsies and urine samples of 89 patients with pediatric LN. Urinary levels of 10 biomarkers [adiponectin, ceruloplasmin, kidney injury molecule-1, monocyte chemotactic protein-1, neutrophil gelatinase-associated lipocalin, osteopontin, transforming growth factor-ß (TGFß), vitamin-D binding protein, liver fatty acid binding protein (LFABP), and transferrin] were measured. Regression analysis was used to identify individual and combinations of biomarkers that determine LN damage status [NIH-chronicity index (NIH-CI) score ≤ 1 vs. ≥ 2] both individually and in combination, and biomarker levels were compared for patients with vs. without renal functional decline, i.e., a 20% reduction of the glomerular filtration rate (GFR) within 12 months of a kidney biopsy.

RESULTS

Adiponectin, LFABP, and osteopontin levels differed significantly with select histological damage features considered in the NIH-CI. The GFR was associated with NIH-CI scores [Pearson correlation coefficient (r) = - 0.49; p < 0.0001] but not proteinuria (r = 0.20; p > 0.05). Similar to the GFR [area under the ROC curve (AUC) = 0.72; p < 0.01], combinations of osteopontin and adiponectin levels showed moderate accuracy [AUC = 0.75; p = 0.003] in discriminating patients by LN damage status. Renal functional decline occurred more commonly with continuously higher levels of the biomarkers, especially of TGFß, transferrin, and LFABP.

CONCLUSION

In combination, urinary levels of adiponectin and osteopontin predict chronic LN damage with similar accuracy as the GFR. Ongoing LN activity as reflected by high levels of LN activity biomarkers heralds renal functional decline.

KEY MESSAGES

• Levels of osteopontin and adiponectin measured at the time of kidney biopsy are good predictors of histological damage with lupus nephritis. • Only about 20% of children with substantial kidney damage from lupus nephritis will have an abnormally low urine creatinine clearance. • Continuously high levels of biomarkers reflecting lupus nephritis activity are risk factors of declining renal function.

Plasma neutrophil gelatinase-associated lipocalin is independently associated with left ventricular hypertrophy and diastolic dysfunction in patients with chronic kidney disease

Background

Cardiovascular disease (CVD) is a leading cause of death in patients with chronic kidney disease (CKD). Left ventricular hypertrophy (LVH) and left ventricular diastolic dysfunction (LVDD) are known as predictors of CVD in these patients. Neutrophil gelatinase-associated lipocalin (NGAL) is a biomarker of acute kidney injury. Recently, elevated NGAL levels have been reported in patients with CVD. This study aimed to evaluate the association between plasma NGAL levels and LVH/LVDD in patients with CKD.

Methods

This study included 332 patients with pre-dialysis CKD (estimated glomerular filtration rate (eGFR) < 60 ml/min/1.73m²). Two-dimensional echocardiography was performed to measure the left ventricular mass index (LVMI). Tissue Doppler imaging was used to measure early mitral inflow velocity (E) and the peak early mitral annular velocity (E'). Diastolic function was estimated using E' and the ratio of E to E' (E/E'). The associations of echocardiographic index with clinical and laboratory variables (age, sex, diabetes, hypertension, eGFR, albumin, uric acid, calcium, phosphate, total cholesterol, hemoglobin, C-reactive protein, intact parathyroid hormone (PTH), the inferior vena cava collapse index (IVCCI) < 50%, and plasma NGAL) were investigated using univariate and multivariate analyses.

Results

In multivariate logistic regression analysis, plasma NGAL was an independent predictor of LVH (OR: 1.02, 95% CI: 1.01–1.02), P < 0.001). In addition, hypertension, intact PTH, and IVCCI < 50% were independent predictors of LVH. Plasma NGAL (OR: 1.02, 95% CI: 1.01–1.02, P < 0.001) was also an independent factor of LVDD. Furthermore, hypertension, intact PTH, and IVCCI < 50% were independent predictors of LVDD. Receiver operating characteristic curve analysis (area under the curve: 0.835, 95% CI: 0.792–0.879) showed the best cutoff value of plasma NGAL for identifying LVDD was ≥ 258 ng/ml with an associated sensitivity of 77.6% and a specificity of 87.6%.

Conclusion

Plasma NGAL levels were independent predictors of LVH and LVDD in patients with pre-dialysis CKD, suggesting that plasma NGAL could be a biomarker for LVH and LVDD in these patients.

More than a simple biomarker: the role of NGAL in cardiovascular and renal diseases

Neutrophil gelatinase-associated lipocalin (NGAL) is a small circulating protein that is highly modulated in a wide variety of pathological situations, making it a useful biomarker of various disease states. It is one of the best markers of acute kidney injury, as it is rapidly released after tubular damage. However, a growing body of evidence highlights an important role for NGAL beyond that of a biomarker of renal dysfunction. Indeed, numerous studies have demonstrated a role for NGAL in both cardiovascular and renal diseases. In the present review, we summarize current knowledge concerning the involvement of NGAL in cardiovascular and renal diseases and discuss the various mechanisms underlying its pathological implications.

Neutrophil gelatinase-associated lipocalin as a risk marker in cardiovascular disease

Neutrophil gelatinase-associated lipocalin (NGAL) is a promising diagnostic biomarker of early acute kidney injury. Increasing evidence suggests that NGAL may also be involved in inflammatory processes in cardiovascular disease. NGAL modulates the enzymatic activity of matrix metalloproteinase-9 (MMP-9), which is an important mediator of plaque instability in atherosclerosis. The complex formation between NGAL and MMP-9 therefore suggests that NGAL might play a role in progression of atherothrombotic disease. This review summarises current data on NGAL in atherosclerosis, acute myocardial infarction, and heart failure.

Urinary neutrophil gelatinase-associated lipocalin and cystatin C compared to the estimated glomerular filtration rate to predict risk in patients with suspected acute myocardial infarction

INTRODUCTION

Impaired renal function, reflected by estimated glomerular filtration rate (eGFR) or cystatin C, is a strong risk predictor in the presence of acute myocardial infarction (AMI). Urinary neutrophil gelatinase-associated lipocalin (uNGAL) is an early marker of acute kidney injury. uNGAL might also be a good predictor of outcome in patients with cardiovascular disease. Aim of the present study was to evaluate the prognostic value of uNGAL compared to eGFR and cystatin C in patients with suspected AMI.

METHODS

1818 patients were enrolled with suspected AMI. Follow-up information on the combined endpoint of death or non-fatal myocardial infarction was obtained 6months after enrolment and was available in 1804 patients. 63 events (3.5%) were registered.

RESULTS

While cystatin C and eGFR were strong risk predictors for the primary endpoint even adjusted for several variables, uNGAL was not independently associated with outcome: When applied continuously uNGAL was associated with outcome but did not remain a statistically significant predictor after several adjustments (i.e. eGFR). By adding cystatin C or uNGAL to GRACE risk score variables, only cystatin C could improve the predictive value while uNGAL showed no improvement.

CONCLUSION

We could show that cystatin C is an independent risk predictor in patients with suspected AMI and cystatin C can add improvement to the commonly used GRACE risk score. In contrast uNGAL is not independently associated with outcome and seems not to add further prognostic information to GRACE risk score.

Plasma Neutrophil Gelatinase-Associated Lipocalin and Predicting Clinically Relevant Worsening Renal Function in Acute Heart Failure

The aim of this study was to evaluate the ability of Neutrophil Gelatinase-Associated Lipocalin (NGAL) to predict clinically relevant worsening renal function (WRF) in acute heart failure (AHF). Plasma NGAL and serum creatinine changes during the first 4 days of admission were investigated in 1447 patients hospitalized for AHF and enrolled in the Placebo-Controlled Randomized Study of the Selective A₁Adenosine Receptor Antagonist Rolofylline for Patients Hospitalized with Acute Decompensated Heart Failure and Volume Overload to Assess Treatment Effect on Congestion and Renal Function (PROTECT) study. WRF was defined as serum creatinine rise ≥ 0.3 mg/dL through day 4. Biomarker patterns were described using linear mixed models. WRF developed in 325 patients (22%). Plasma NGAL did not rise earlier than creatinine in patients with WRF. After multivariable adjustment, baseline plasma NGAL, but not creatinine, predicted WRF. AUCs for WRF prediction were modest (<0.60) for all models. NGAL did not independently predict death or rehospitalization (p = n.s.). Patients with WRF and high baseline plasma NGAL had a greater risk of death, and renal or cardiovascular rehospitalization by 60 days than patients with WRF and a low baseline plasma NGAL (p for interaction = 0.024). A rise in plasma NGAL after baseline was associated with a worse outcome in patients with WRF, but not in patients without WRF (p = 0.007). On the basis of these results, plasma NGAL does not provide additional, clinically relevant information about the occurrence of WRF in patients with AHF.

Increased susceptibility to structural acute kidney injury in a mouse model of presymptomatic cardiomyopathy

The early events that signal renal dysfunction in presymptomatic heart failure are unclear. We tested the hypothesis that functional and mechanistic changes occur in the kidney that precede the development of symptomatic heart failure. We employed a transgenic mouse model with cardiomyocyte-specific overexpression of mutant α-B-crystallin that develops slowly progressive cardiomyopathy. Presymptomatic transgenic mice displayed an increase in serum creatinine (1.17 ± 0.34 vs. wild type 0.65 ± 0.16 mg/dl, P < 0.05) and in urinary neutrophil gelatinase-associated lipocalin (NGAL; 278.92 ± 176.24 vs. wild type 49.11 ± 22.79 ng/ml, P < 0.05) but no renal fibrosis. Presymptomatic transgenic mouse kidneys exhibited a twofold upregulation of the Ren1 gene, marked overexpression of renin protein in the tubules, and a worsened response to ischemia-reperfusion injury based on serum creatinine (2.77 ± 0.66 in transgenic mice vs. 2.01 ± 0.58 mg/dl in wild type, P < 0.05), urine NGAL (9,198.79 ± 3,799.52 in transgenic mice vs. 3,252.94 ± 2,420.36 ng/ml in wild type, P < 0.05), tubule dilation score (3.4 ± 0.5 in transgenic mice vs. 2.6 ± 0.5 in wild type, P < 0.05), tubule cast score (3.2 ± 0.4 in transgenic mice vs. 2.5 ± 0.5 in wild type, P < 0.05), and TdT-mediated dUTP nick-end labeling (TUNEL)-positive nuclei (10.1 ± 2.1 in the transgenic group vs. 5.7 ± 1.6 per 100 cells counted in wild type, P < 0.01). Our findings indicate functional renal impairment, urinary biomarker elevations, and induction of renin gene and protein expression in the kidney that occur in early presymptomatic heart failure, which increase the susceptibility to subsequent acute kidney injury.

Renal function assessment in heart failure

Renal function is one of the most consistent prognostic determinants in heart failure. The prognostic information it provides is independent of the ejection fraction and functional status. This article reviews the various renal function assessment measures, with special emphasis on the fact that the patient's clinical situation and response to the heart failure treatment should be considered for the correct interpretation of the results. Finally, we review the literature on the performance of tubular damage biomarkers.

Biomarkers in acute kidney injury - pathophysiological basis and clinical performance

Various biomarkers of acute kidney injury (AKI) have been discovered and characterized in the recent past. These molecules can be detected in urine or blood and signify structural damage to the kidney. Clinically, they are proposed as adjunct diagnostics to serum creatinine and urinary output to improve the early detection, differential diagnosis and prognostic assessment of AKI. The most obvious requirements for a biomarker include its reflection of the underlying pathophysiology of the disease. Hence, a biomarker of AKI should derive from the injured kidney and reflect a molecular process intimately connected with tissue injury. Here, we provide an overview of the basic pathophysiology, the cellular sources and the clinical performance of the most important currently proposed biomarkers of AKI: neutrophil gelatinase-associated lipocalin (NGAL), kidney injury molecule-1 (KIM-1), liver-type fatty acid-binding protein (L-FABP), interleukin-18 (IL-18), insulin-like growth factor-binding protein 7 (IGFBP7), tissue inhibitor of metalloproteinase 2 (TIMP-2) and calprotectin (S100A8/9). We also acknowledge each biomarker's advantages and disadvantages as well as important knowledge gaps and perspectives for future studies.

Neutrophil gelatinase-associated lipocalin levels are U-shaped in the Ludwigshafen Risk and Cardiovascular Health (LURIC) study-Impact for mortality

INTRODUCTION

Neutrophil gelatinase-associated lipocalin (NGAL) is a glycoprotein released by damaged renal tubular cells and mature neutrophils. It is elevated in kidney injury, but also in patients with coronary artery disease (CAD) and myocardial infarction. We investigated the prognostic value of NGAL for total and cardiovascular mortality in patients undergoing coronary angiography without history of renal insufficiency at inclusion into the study.

PARTICIPANTS

The LURIC study is an ongoing prospective cohort study of patients referred for coronary angiography and is designed to evaluate determinants of cardiovascular health.

RESULTS

NGAL was determined in plasma of 2997 persons (mean age: 62.7 years; 69.7% men) with a follow up for 10 years. 2358 patients suffered from CAD and 638 did not-these patients served as controls. Stable CAD was found in 1408 and unstable CAD in 950 patients. Death rate from cardiovascular events and all causes was highest in patients within the 4th quartile of NGAL (≥56 ng/ml, p<0.001 vs third quartile), even after adjustment for age and gender. According to multivariable-adjusted Cox analysis adjusting for well-known cardiovascular risk factors, as well as lipid lowering therapy, angiographic CAD, and C-reactive protein we found patients in the highest NGAL quartile being at increased risk for cardiovascular (hazard ratio (HR) 1.33, 95%CI 1.05-1.67, p = 0.016) and all cause mortality (HR 1.29 95%CI 1.07-1.55, p = 0.007) compared to those in the third quartile. The lowest risk was seen in the third quartile of NGAL (41-56 ng/ml) suggesting a U-shaped relationship between NGAL and mortality. Further adjustment for creatinine abrogated the predictive effect of NGAL. However, the 3rd and 4th quartiles of NGAL were significantly associated with higher neutrophil counts, which were associated with CAD, non-ST elevation and ST-elevation myocardial infarction (p<0.05).

CONCLUSIONS

Plasma NGAL concentrations are mainly derived from neutrophils and do not predict mortality independent of renal function.

Urinary NGAL-Positive Acute Kidney Injury and Poor Long-term Outcomes in Hospitalized Patients

Introduction

Neutrophil gelatinase−associated lipocalin (NGAL) is a widely studied biomarker of renal tubular injury. Urinary NGAL (uNGAL) during acute kidney injury (AKI) predicts short-term adverse outcomes. However, the long-term predictive value is unknown.

Methods

We performed a prospective observational study of 145 patients with hospital-acquired AKI according to Risk, Injury, Failure, Loss of kidney function, and End-stage kidney disease (RIFLE) criteria and analyzed the long-term predictive value of uNGAL at the time of AKI. We defined a composite outcome of all-cause mortality and the development of end-stage renal disease (ESRD).

Results

In all, 61 AKI patients died and 22 developed ESRD within 6 months. The uNGAL levels were significantly higher in patients with poor long-term outcomes. uNGAL levels ≥362 μg/l (highest quartile) and uNGAL levels between 95 and 362 μg/l (third quartile) were associated with hazard ratios of 3.7 (95% confidence interval, 2.1–6.5) and 1.9 (1.1–3.5), respectively, compared with uNGAL levels <95 μg/l (lower quartiles). After 6 months, 67% and 43% of patients within the highest and third uNGAL quartile, respectively, had either progressed to ESRD or died, compared to only 21% of patients with uNGAL in the lower 2 quartiles (P < 0.001). In multivariable Cox regression analyses accounting for conventional predictors, uNGAL was the strongest independent predictor of adverse long-term outcomes. The association of uNGAL levels and poor long-term outcomes remained significant in the subgroup of 107 AKI survivors discharged without requiring dialysis (P = 0.002).

Discussion

These data indicate that elevated uNGAL levels at AKI diagnosis predict poor long-term outcomes.

Lipocalin-2 inhibits autophagy and induces insulin resistance in H9c2 cells

Lipocalin-2 (Lcn2; also known as neutrophil gelatinase associated lipocalin, NGAL) levels are increased in obesity and diabetes and associate with insulin resistance. Correlations exist between Lcn2 levels and various forms or stages of heart failure. Insulin resistance and autophagy both play well-established roles in cardiomyopathy. However, little is known about the impact of Lcn2 on insulin signaling in cardiomyocytes. In this study, we treated H9c2 cells with recombinant Lcn2 for 1 h followed by dose- and time-dependent insulin treatment and found that Lcn2 attenuated insulin signaling assessed via phosphorylation of Akt and p70S6K. We used multiple assays to demonstrate that Lcn2 reduced autophagic flux. First, Lcn2 reduced pULK1 S555, increased pULK1 S757 and reduced LC3-II levels determined by Western blotting. We validated the use of DQ-BSA to assess autolysosomal protein degradation and this together with MagicRed cathepsin B assay indicated that Lcn2 reduced lysosomal degradative activity. Furthermore, we generated H9c2 cells stably expressing tandem fluorescent RFP/GFP-LC3 and this approach verified that Lcn2 decreased autophagic flux. We also created an autophagy-deficient H9c2 cell model by overexpressing a dominant-negative Atg5 mutant and found that reduced autophagy levels also induced insulin resistance. Adding rapamycin after Lcn2 could stimulate autophagy and recover insulin sensitivity. In conclusion, our study indicated that acute Lcn2 treatment caused insulin resistance and use of gain and loss of function approaches elucidated a causative link between autophagy inhibition and regulation of insulin sensitivity by Lcn2.

Plasma Neutrophil Gelatinase-Associated Lipocalin as a Predictor of Cardiovascular Events in Patients with Chronic Kidney Disease

Background. Our aim was to assess plasma neutrophil gelatinase-associated lipocalin (NGAL) as a predictor of cardiovascular (CV) events in patients with chronic kidney disease (CKD) and no history of CV events. Methods. This was a prospective observational cohort study of 252 patients with predialysis CKD. CV events were defined as CV death, acute coronary syndrome, and hospitalization for worsening heart failure, stroke, and aortic dissection. Results. During a median follow-up period of 63 months, 36 CV events occurred. On Cox stepwise multivariate analysis, plasma NGAL and B-type natriuretic peptide (BNP) were significant predictors of CV events. Kaplan-Meier incidence rates of CV event-free survival at 5 years were 96.6%, 92.9%, 85.9%, and 61.3%, respectively, among quartiles of plasma NGAL (P < 0.0001). The C-index for the receiver-operating characteristic curves for CV events was greater when plasma NGAL was added to an established risk model (0.801, 95% CI 0.717–0.885), compared to the model without plasma NGAL (0.746, 95% CI 0.653–0.840, P = 0.021). Conclusion. Elevated plasma NGAL could predict future CV events in CKD patients with no history of CV events and add incremental value to the established risk model.

Plasma levels of neutrophil gelatinase-associated lipocalin in children with heart failure

INTRODUCTION

Data about plasma levels of neutrophil gelatinase-associated lipocalin (NGAL) in children with heart failure (HF) are very limited. NGAL is used widely as a biomarker for the diagnosis of renal injury in numerous clinical studies. The aim of this study is to investigate the plasma NGAL in children with HF caused by idiopathic dilated cardiomyopathy (IDCM) and its relation to the severity of HF.

MATERIAL AND METHODS

In a case-control study, 30 nondiabetic children, aged -16 years (all have IDCM) recruited from the pediatric department of our institute together with 30 healthy children were prospectively enrolled in this study. Patients underwent a detailed history taking, clinical examination, New York Heart Association (NYHA) class assessment and echocardiographic evaluation. Plasma levels of NGAL were measured by enzyme-linked immunosorbent assay.

RESULTS

Plasma levels of NGAL were significantly higher in children with HF compared with healthy controls (mean: 290.97 versus 144.33, p < 0.0001). The relationship between NGAL and the severity of HF was investigated. However, we did not find any statistically significant relationship between plasma NGAL levels and indices of myocardial function.

CONCLUSIONS

NGAL levels were significantly increased in children with HF caused by IDCM. However, there was no significant relationship between plasma NGAL levels and indices of myocardial function. Future multicenter clinical studies in a large population addressing the natural course of NGAL in HF and its potential as a treatment target are needed in the near future.

Iron metabolism and regulation by neutrophil gelatinase-associated lipocalin in cardiomyopathy

Neutrophil gelatinase-associated lipocalin (NGAL) has recently become established as an important contributor to the pathophysiology of cardiovascular disease. Accordingly, it is now viewed as an attractive candidate as a biomarker for various disease states, and in particular has recently become regarded as one of the best diagnostic biomarkers available for acute kidney injury. Nevertheless, the precise physiological effects of NGAL on the heart and the significance of their alterations during the development of heart failure are only now beginning to be characterized. Furthermore, the mechanisms via which NGAL mediates its effects are unclear because there is no conventional receptor signalling pathway. Instead, previous work suggests that regulation of iron metabolism could represent an important mechanism of NGAL action, with wide-ranging consequences spanning metabolic and cardiovascular diseases to host defence against bacterial infection. In the present review, we summarize rapidly emerging evidence for the role of NGAL in regulating heart failure. In particular, we focus on iron transport as a mechanism of NGAL action and discuss this in the context of the existing strong associations between iron overload and iron deficiency with cardiomyopathy.

Serum neutrophil gelatinase-associated lipocalin is associated with cardiovascular events in patients with chronic kidney disease

BACKGROUND

Neutrophil gelatinase-associated lipocalin (NGAL) is a member of the lipocalin family best known as a novel and early marker of acute kidney injury (AKI). Recent data suggest that NGQueryAL is not only a marker of AKI, but also an important player in the vascular remodeling, atherosclerotic plaque stability and thrombus formation. We conducted this study to investigate the association of serum NGAL levels with fatal and composite (fatal and non-fatal) cardiovascular events (CVE) in a cohort of patients with stage 1-5 CKD.

METHODS

This was an observational cohort study in which serum NGAL was obtained from 298 CKD (stages 1-5) patients. Fatal and composite CVE were recorded for a median 41 months. We examined alteration of serum NGAL through CKD groups as well as association with inflammatory markers. We also performed a Cox regression analysis to determine the association of NGAL with predefined clinical outcomes.

RESULTS

The median value of NGAL was 50.5 ng/mL (IR 47.6-54.9 ng/mL), and higher NGAL values were recorded in diabetic patients. In a multiple linear regression model, including all univariate associates of NGAL, only log eGFR, log hs-CRP and log HDL cholesterol maintained an independent association with log NGAL. During the observational period, 30 patients died due to cardiovascular causes and 69 non-fatal CVE were registered. In the fully adjusted model, we observed a 2.08-fold increase in the risk of fatal CVE and a 1.50-fold increase in the risk of fatal and non-fatal CVE for each increment of 1 SD in log NGAL values.

CONCLUSIONS

This is the first study that shows that serum NGAL is associated with cardiovascular events (fatal and non-fatal) in patients with CKD, independently of traditional risk factors, renal function and inflammation.

Characterization of Changes in Global Genes Expression in the Distal Colon of Loperamide-Induced Constipation SD Rats in Response to the Laxative Effects of Liriope platyphylla

To characterize the changes in global gene expression in the distal colon of constipated SD rats in response to the laxative effects of aqueous extracts of Liriope platyphylla (AEtLP), including isoflavone, saponin, oligosaccharide, succinic acid and hydroxyproline, the total RNA extracted from the distal colon of AEtLP-treated constipation rats was hybridized to oligonucleotide microarrays. The AEtLP treated rats showed an increase in the number of stools, mucosa thickness, flat luminal surface thickness, mucin secretion, and crypt number. Overall, compared to the controls, 581 genes were up-regulated and 216 genes were down-regulated by the constipation induced by loperamide in the constipated rats. After the AEtLP treatment, 67 genes were up-regulated and 421 genes were down-regulated. Among the transcripts up-regulated by constipation, 89 were significantly down-regulated and 22 were recovered to the normal levels by the AEtLP treatment. The major genes in the down-regulated categories included Slc9a5, klk10, Fgf15, and Alpi, whereas the major genes in the recovered categories were Cyp2b2, Ace, G6pc, and Setbp1. On the other hand, after the AEtLP treatment, ten of these genes down-regulated by constipation were up-regulated significantly and five were recovered to the normal levels. The major genes in the up-regulated categories included Serpina3n, Lcn2 and Slc5a8, whereas the major genes in the recovered categories were Tmem45a, Rerg and Rgc32. These results indicate that several gene functional groups and individual genes as constipation biomarkers respond to an AEtLP treatment in constipated model rats.

The role of urine neutrophil gelatinase--associated lipocalin (NGAL) in acute heart failure in patients with ST--elevation myocardial infarction

BACKGROUND

Neutrophil gelatinase-associated lipocalin (NGAL) is a novel early marker of acute kidney injury for which has been shown that it can also be released from the injured myocardium. Our aim was to correlate urine NGAL with markers of in-hospital heart failure in patients with acute ST-elevation myocardial infarction (STEMI).

METHODS

We prospectively included 61 consecutive STEMI patients after primary percutaneous coronary intervention and estimated admission and in-hospital urine NGAL, serum creatinine, troponin I, leucocytes, CRP, N-terminal pro brain natriuretic peptide (NT-proBNP) levels and ejection fraction by echocardiography. Urine NGAL levels were compared between patients with and without HF defined as serum NT-proBNP > 400 pmol/l and were correlated to markers of heart failure, inflammations and of kidney function.

RESULTS

Urine NGAL levels and CRP was significantly higher in participants with heart failure compared to those with NT-proBNP below 400 pmol/l. Urine NGAL level of 50 ng/ml had 90 % specificity for HF, the sensitivity was low at 25 %. Comparison of participants with NGAL levels < 50 ng/ml and ≥ 50 ng/ml at admission and after 12 h revealed a significant difference in NT-proBNP levels, left ventricle ejection fraction, markers of inflammation and of kidney function. Urine NGAL level was independently associated with NT-proBNP level.

CONCLUSIONS

The level of urine NGAL early after myocardial infarction is associated with NT-proBNP concentration and even NGAL levels below 137 ng/ml, the usually reported normal cut-off value, had high specificity for HF in our sample.

Neutrophil gelatinase-associated lipocalin (NGAL) in heart transplant recipients after conversion to everolimus therapy

BACKGROUND

Due to the lack of nephrotoxic activity, proliferation signal inhibitors (PSI) such as everolimus are recommended for immunosuppression after heart transplantation, but the assessment of renal function in patients receiving PSI has led to conflicting results. We examined renal integrity and function using neutrophil gelatinase-associated lipocalin (NGAL) and conventional markers [plasma creatinine, cystatin C, urine albumin, α1-microglobulin (α1M)] in heart transplant patients, who underwent conversion to everolimus due to allograft vasculopathy, graft rejection episodes, or renal function deterioration, and in patients maintained on calcineurin inhibitors (CNI).

METHODS

This cross-sectional study included 121 consecutive heart transplant recipients: 44 patients received CNI-free immunosuppressive therapy with everolimus and 77 patients received CNI. Renal parameters were determined in plasma and urine samples using standard enzymatic or immunochemical methods.

RESULTS

Heart transplant recipients receiving everolimus therapy had significantly lower NGAL concentrations in plasma [median (95% CI): 128 (97-176)ng/mL vs. 252 (224-283)ng/mL, p<0.001] and urine [median (95% CI): 6.4 (4.5-7.6)ng/g vs. 15.7 (10.2-25.9)ng/g creatinine, p<0.001]. In contrast, no significant differences were observed between everolimus- and CNI-treated groups with regard to creatinine and cystatin C, as well as urine albumin and α1M levels. Significant correlations were noted between plasma NGAL and creatinine (r=0.42, p<0.001), cystatin C (r=0.44, p<0.001), N-terminal brain natriuretic propeptide (r=0.31, p<0.01) and indicators of chronic inflammation [lipoprotein-associated phospholipase A2 (Lp-PLA2), r=0.31, p<0.01] and soluble CD40 ligand (sCD40L, r=0.22, p<0.05), and between urinary NGAL and α1M (r=0.21, p<0.05). Multiple regression analysis indicated that cystatin C and Lp-PLA2 were the best predictors of plasma NGAL.

CONCLUSION

The present study documents reduced plasma and urinary NGAL levels in the absence of differences in conventional renal parameters in patients on CNI-free immunosuppressive therapy with everolimus. These results support favorable effects of everolimus on renal integrity in heart transplant recipients.

Mechanism and clinical evidence of lipocalin-2 and adipocyte fatty acid-binding protein linking obesity and atherosclerosis

Obesity is considered to be a chronic inflammatory state in which the dysfunction of adipose tissue plays a central role. The adipokines, which are cytokines secreted by adipose tissue, are key links between obesity and related diseases such as metabolic syndrome and atherosclerosis. LCN2 and A-FABP, both of which are major adipokines predominantly produced in adipose tissue, have recently been shown to be pivotal modulators of vascular function. However, different adipokines modulate the development of atherosclerosis in distinctive manners, which are partly attributable to their unique regulatory mechanisms and functions. This review highlights recent advances in the understanding of the role of two adipokines in mediating chronic inflammation and the pathogenesis of atherosclerosis.

The different molecular forms of urine neutrophil gelatinase-associated lipocalin present in dogs with urinary diseases

Background

Neutrophil gelatinase-associated lipocalin (NGAL) is a useful biomarker for the early prediction of renal diseases. NGAL may exist as monomer, dimer and/or NGAL/MMP-9 complex forms in humans. In this study, the existence of various forms of NGAL in urine (uNGAL) was determined and whether these forms are related to the different urinary diseases found in dogs is further discussed.

Results

Eighty-one urine samples from dogs with different forms of renal disease (41), pyuria (19) and a number of non-renal related diseases (10), as well as healthy dogs (11), were collected. uNGAL concentrations and their molecular forms in dogs were measured by ELISA and Western blot analysis, respectively. The uNGAL concentrations of dogs with pyuria (median: 15.35 ng/mL) were significantly higher than those of the healthy control animals (median: 3.92 ng/mL) (p < 0.01), but lower than those of dogs with renal diseases (median: 23.77 ng/mL). Each NGAL molecular form could be detected in dog urine. In particular, monomer was detected more frequently in patients with renal disease than those with non-renal diseases; while the dimer form appeared in a significantly higher percentage of cases with pyuria compared to those without pyuria. The NGAL/MMP-9 complex was found to exist not only in the patients with cystitis, but also in the cases with renal injury.

Conclusion

Different molecular forms of uNGAL can indicate different origins of the urinary abnormalities. Determining the molecular forms of uNGAL present in diseased dogs may provide clinical workers with a tool that will help the early and more precise detection of different urinary diseases.

Acute kidney injury urinary biomarker time-courses

Factors which modify the excretion profiles of acute kidney injury biomarkers are difficult to measure. To facilitate biomarker choice and interpretation we modelled key modifying factors: extent of hyperfiltration or reduced glomerular filtration rate, structural damage, and reduced nephron number. The time-courses of pre-formed, induced (upregulated), and filtered biomarker concentrations were modelled in single nephrons, then combined to construct three multiple-nephron models: a healthy kidney with normal nephron number, a non-diabetic hyperfiltering kidney with reduced nephron number but maintained total glomerular filtration rate, and a chronic kidney disease kidney with reduced nephron number and reduced glomerular filtration rate. Time-courses for each model were derived for acute kidney injury scenarios of structural damage and/or reduced nephron number. The model predicted that pre-formed biomarkers would respond quickest to injury with a brief period of elevation, which would be easily missed in clinical scenarios. Induced biomarker time-courses would be influenced by biomarker-specific physiology and the balance between insult severity (which increased single nephron excretion), the number of remaining nephrons (reduced total excretion), and the extent of glomerular filtration rate reduction (increased concentration). Filtered biomarkers have the longest time-course because plasma levels increased following glomerular filtration rate decrease. Peak concentration and profile depended on the extent of damage to the reabsorption mechanism and recovery rate. Rapid recovery may be detected through a rapid reduction in urinary concentration. For all biomarkers, impaired hyperfiltration substantially increased concentration, especially with chronic kidney disease. For clinical validation of these model-derived predictions the clinical biomarker of choice will depend on timing in relation to renal insult and interpretation will require the pre-insult nephron number (renal mass) and detection of hyperfiltration.

Neutrophil Gelatinase-Associated Lipocalin and depression in patients with chronic heart failure

Depression adversely affects prognosis in heart failure (HF) patients. Inflammation is indicated as potential biological pathway in this co-morbidity. Since increased levels of the cytokine Neutrophil Gelatinase-Associated Lipocalin (NGAL) are predictive for HF prognosis, and recently indicated in patients with major depression, this study examined the association of serum NGAL levels with symptoms of depression in patients with HF. Serum NGAL levels were measured in 104 patients with HF (left ventricular ejection fraction, LVEF⩽40). Depression, evaluated using the Beck Depression Inventory (BDI; total score, somatic and cognitive component), and the Hamilton Depression Rating scale (HAMD), at baseline and 12months follow-up, was associated with NGAL levels using mixed model analysis. Analyses were adjusted for demographics measures, disease severity indicators, inflammation, comorbidity and medication. Increased serum NGAL levels were significantly associated with depression measured by HAMD (baseline: r=0.25, p<.05) and BDI (baseline: r=0.22, p<.05; 12months: r=0.37, p<.01). This association remained significant after adjustment for covariates; age, sex, time, LVEF, and creatinine (HAMD, t=2.01, p=.047; BDI, t=2.28, p=.024). NGAL was significantly associated with somatic- (p=0.004), but not cognitive depressive symptoms (p=0.32). NGAL levels were associated with the experienced HF-related functional limitations (6min walk test), rather than the severity of cardiac dysfunction (LVEF). This study indicates that depression in patients with chronic HF is associated with elevated NGAL levels, independent of clinical severity of the underlying disease.

Cardiorenal syndrome

Cardiorenal syndrome (CRS) includes a broad spectrum of diseases within which both the heart and kidneys are involved, acutely or chronically. An effective classification of CRS in 2008 essentially divides CRS in two main groups, cardiorenal and renocardiac CRS, based on primum movens of disease (cardiac or renal); both cardiorenal and renocardiac CRS are then divided into acute and chronic, according to onset of disease. The fifth type of CRS integrates all cardiorenal involvement induced by systemic disease. This article addresses the pathophysiology, diagnosis, treatment, and outcomes of the 5 distinct types of CRS.

Management of chronic heart failure: biomarkers, monitors, and disease management programs

BACKGROUND

The management of patients with heart failure has been evolving given the complex nature of the disease and the increasing number of patients.

FINDINGS

Biomarkers, and in particular the natriuretic peptides, have been studied to assist with diagnosis, chronic management, and prognosis in patients with heart failure. Several new biomarkers are emerging and may be used individually or in combination with the natriuretic peptides. The use of cardiac monitoring devices and disease management programs is being established to assist in the care of patients with chronic heart failure. Interventions using phone calls, telemedicine devices, intracardiac pressure monitors, and implantable cardioverter defibrillators have been investigated.

CONCLUSIONS

The combination of biomarkers, monitoring devices, and disease management programs shows promise for improving care in this challenging patient population.

Prognostic value of plasma neutrophil gelatinase-associated lipocalin for mortality in patients with heart failure

BACKGROUND

In patients with heart failure, renal dysfunction is associated with a poor outcome. We aimed to assess the prognostic value of plasma neutrophil gelatinase-associated lipocalin (NGAL), a novel marker of renal tubular damage, in patients with heart failure with or without renal dysfunction, and compare it with 2 frequently used biomarkers of chronic kidney disease.

METHODS AND RESULTS

Plasma NGAL, estimated glomerular filtration rate (eGFR), and cystatin C were assessed in 562 patients with heart failure. Chronic kidney disease was defined as eGFR<60 mL/min per 1.73 m2. Outcome was all-cause mortality at 36 months. Mean age was 71±11 years, 61% were men, and 97% were in New York Heart Association functional class II/III. Mean baseline eGFR was 54±20 mL/min per 1.73 m2, mean cystatin C was 11.2 (7.7-16.2) mg/L, and median plasma NGAL was 85 (60-123) ng/mL. Higher plasma NGAL levels were independently associated with an increased risk of all-cause mortality, in patients with and without chronic kidney disease (hazard ratio [per SD increase in log NGAL]=1.45 [1.22-1.72]; P<0.001 and hazard ratio=1.51 [1.06-2.16]; P=0.023, respectively). Similarly, both in patients with high and low cystatin C (median cut-off), higher plasma NGAL levels were independently associated with an increased risk of all-cause mortality. Moreover, when NGAL was entered in the multivariable risk prediction model, eGFR (P=0.616) and cystatin C (P=0.937) were no longer associated with mortality.

CONCLUSIONS

Plasma NGAL predicts mortality in patients with heart failure, both in patients with and without chronic kidney disease and is a stronger predictor for mortality than the established renal function indices eGFR and cystatin C.

Clinical utility of biomarkers in chronic kidney disease and chronic heart failure

Biomarkers have an increasingly important clinical role in managing patients with heart failure as well as those with kidney disease, both common conditions with generally poor prognostic outcomes and huge impacts on healthcare economics. For patients with chronic heart failure, biomarkers have become centre place in streamlining diagnostic pathways as well as identifying those with worse prognosis. There is much interest in the role for biomarkers in identifying patients at risk of acute kidney injury, although a number of these currently remain as research tools or are in the early stages of evaluation in clinical practice. Patients with cardiorenal syndrome represent a particular challenge to the clinician, and recent studies have suggested a valuable clinical role for certain biomarkers in this setting, either on their own or in combination. This paper will focus on biomarkers with a current clinical role in patients with cardiorenal disease (natriuretic peptides and neutrophil gelatinase-associated lipocalin), although brief reference will be made to other biomarkers with potential future application.

Current and novel renal biomarkers in heart failure

Renal function is the most important predictor of clinical outcome in heart failure (HF). It is therefore essential to have accurate and reliable measurement of renal function and early specific markers of renal impairment in patients with HF. Several renal functional entities exist, including glomerular filtration (GFR), glomerular permeability, tubulointerstitial damage, and endocrine function. Different markers have been studied that can be used to determine changes and the effect of treatment in these entities. In the present review, we summarize current and novel markers that give an assessment of renal function and prognosis in the setting of acute and chronic HF.

Urinary neutrophil gelatinase-associated lipocalin (NGAL) is associated with mortality in a community-based cohort of older Swedish men

OBJECTIVE

Neutrophil gelatinase-associated lipocalin (NGAL) indicates tubular kidney damage, neutrophil activation and possibly atherogenesis, however the prospective association between urinary NGAL (u-NGAL) and cardiovascular death in the community is not known.

METHODS

This study evaluates the association between urinary and serum NGAL and mortality in a Swedish population of 597 men aged 78 years. During the study (median follow-up 8.1 years) 261 men died, 90 of cardiovascular causes.

RESULTS

U-NGAL was associated with increased all-cause and cardiovascular mortality (HR 2.0 for quartile 4 vs. quartile 1, 95% CI 1.0-4.0, P < 0.05) in Cox regression models independently of cardiovascular risk factors, CRP and cystatin C estimated glomerular filtration rate (eGFRCysC) but not urinary Albumin (u-Alb). A combination of low eGFRCysC (≤60 mL/min), high u-Alb (≥3 mg/mmol Cr) and high u-NGAL (≥1.19 μg/mmol Cr) was associated with a 9-fold increased cardiovascular mortality (P < 0.001) and a 3-fold increased all-cause mortality (P < 0.001). Serum NGAL was associated with increased all-cause mortality risk independent of other cardiovascular risk factors (HR 1.4 for quartile 4 vs.1, 95% CI 1.0-1.9, P < 0.05) but not after adjustment with CRP, eGFRCysC or u-Alb.

CONCLUSION

This community study is the first to show that the tubular kidney biomarker u-NGAL associated with increased cardiovascular and all-cause mortality independent of cardiovascular risk factors and glomerular filtration. Additional research is needed to evaluate the utility of NGAL in clinical practice.

Urinary neutrophil gelatinase-associated lipocalin may aid prediction of renal decline in patients with non-proteinuric Stages 3 and 4 chronic kidney disease (CKD)

BACKGROUND

Chronic kidney disease (CKD) is an increasing public health issue. It is therefore potentially highly advantageous to identify patients at risk of accelerated renal progression and death. Neutrophil gelatinase-associated lipocalin (NGAL) is an established urinary biomarker for acute kidney injury, but it is not known whether adding urinary NGAL (uNGAL) measurements to conventional risk factors will improve risk assessment in the setting of chronic disease.

METHODS

This is a prospective observational cohort study of 158 patients with Stage 3 or 4 CKD. The ability of baseline uNGAL to improve prediction of outcome was assessed by multivariate modelling and a number of metrics including net reclassification analysis. A primary composite endpoint of all-cause mortality or progression to end-stage renal disease (ESRD) requiring renal replacement therapy (RRT) at 2 years and a secondary endpoint of ≥5 mL/min/1.73 m(2) decline in the estimated glomerular filtration rate (eGFR) after 1 year were considered.

RESULTS

Forty patients (25%) reached the primary composite endpoint, 20 of whom died. Twenty-seven patients (19%) reached the secondary endpoint of a ≥5 mL/min/1.73 m(2) decline in the eGFR. The baseline uNGAL-to-creatinine ratio (uNCR) was associated with the combined endpoint of death or initiation of RRT (HR per 5 µg/mmol increase 1.27, 95% CI: 1.01-1.60, P = 0.036) independent of conventional cardiovascular and renal risk factors, including proteinuria. In separate analysis of these two competing endpoints, however, uNCR only remained associated with increased risk of progression to ESRD requiring RRT. Higher baseline uNCR was also independently predictive of rapid renal decline over 1 year (HR per 5 µg/mmol increase 1.47, 95% CI: 1.06-2.06, P = 0.022). Addition of uNCR to the base model resulted in a significant increase in discrimination for the secondary (C-statistic 0.76-0.85, P = 0.001) but not the primary endpoint (P = 0.276). Reclassification analysis on the other hand, demonstrated an improvement in risk predication of both primary and secondary endpoints by incorporating uNCR into the base model, but only in those with low-level urine protein excretion (<28 mg/mmol), with category-free net reclassification improvement (NRI) scores of 64% (95% CI: 8-70; P = 0.019) and 79% (95% CI: 12-83; P = 0.009), respectively.

CONCLUSION

The utilization of uNCR in addition to conventional established cardiovascular and renal risk factors may improve the prediction of disease progression in elderly Caucasian pre-dialysis CKD patients with low-grade proteinuria.

Neutrophil gelatinase-associated lipocalin as a biomarker of cardiovascular disease: a systematic review

BACKGROUND

Neutrophil gelatinase-associated lipocalin (NGAL) is a biomarker of acute kidney injury (AKI). Recently, elevated NGAL levels have also been reported in heart failure, coronary heart disease, and stroke. Other studies demonstrate that NGAL is upregulated in failing myocardium and in atherosclerotic plaque. Our aim was to synthesize the current evidence on NGAL and cardiovascular disease (CVD), and to clarify the prognostic significance of systemic NGAL levels in CVD.

METHODS

We performed a systematic review to identify experimental and human studies on NGAL and CVD. We excluded articles which specifically dealt with AKI or renal endpoints.

RESULTS

We identified 22 studies, including both animal and human data. NGAL is highly expressed in the heart, both in failing myocardium and myocarditis, and is also expressed in atherosclerotic plaques. Areas of co-localization of NGAL and matrix metalloproteinase (MMP)-9 exhibited increased MMP-9 proteolytic activity. Systemic NGAL levels correlated with renal function and severity of CVD in several, but not all, studies. An association between elevated systemic NGAL levels and clinical outcomes (e.g., death, hospital readmissions) were reported in six CVD studies, but these had limited adjustment for potential confounders.

CONCLUSIONS

There is ample literature to support a putative role of NGAL in the pathophysiology of CVD, but at present there is insufficient data regarding the clinical utility of systemic NGAL levels in the management of CVD. Available evidence regarding NGAL as a predictor of outcomes in CVD is very limited.

Frontiers of therapy for patients with heart failure

This review broadly covers advances in heart failure, which is responsible for significant morbidity, mortality, and cost in the United States. It is a heterogeneous condition, and accurate classification helps ensure appropriate application of evidence-based therapies. Hemodynamics are important in acute heart failure syndromes and may help tailor therapy. Neurohormonal modulation forms the cornerstone of chronic systolic heart failure treatment but does not affect outcomes in diastolic heart failure where management goals emphasize optimization of central volume, blood pressure, and atrial rhythm, as well as the treatment of comorbidities. Frontiers of heart failure therapy range from advances in pharmacology (novel inotropic agents and neurohormonal modulators), to cell biology (nucleic acid-based drugs and cell therapy) to biomedical engineering (devices such as ultrafiltration, biventricular pacemakers, implantable cardiac defibrillators, remote monitoring systems, and left ventricular assist devices), and to health systems (risk stratification and integrated care of comorbidities). The ultimate frontier will be to integrate these data effectively to ensure that patients with heart failure consistently receive the best evidenced-based care possible.

Role of biomarkers in the diagnosis and prognosis of acute kidney injury in patients with cardiorenal syndrome

Cardiac and renal disease frequently coexist but have long been difficult to diagnose in a timely manner and treat effectively. Noninvasive and cost-effective biomarkers are needed to help identify cardiac patients who are at risk of acute kidney injury early in the course of disease. Biomarkers can provide insights into underlying mechanisms and lead to a better understanding of complex disease states such as the cardiorenal syndrome, which can lead to better therapies and, ultimately, to improved patient outcomes. The natriuretic peptides are established biomarkers in heart failure and have set the standard for how a well-validated biomarker can be useful for diagnosis/prognosis, monitoring response to therapy and chronic disease management. For patients with acute kidney injury in the setting of cardiac disease, new biomarkers such as neutrophil gelatinase-associated lipocalin, cystatin C, kidney injury molecule-1 and IL-18 are emerging as early signals of renal dysfunction prior to any elevations in serum creatinine. Other promising candidate biomarkers for the early diagnosis of acute kidney injury include osteopontin, N-acetyl-b-d-glucosaminidase, stromal cell-derived factor-1 and exosomes. More research with all of these novel biomarkers is needed; however, the early results are very promising.