Neutrophil Gelatinase-associated Lipocalin Production Research Articles

NGAL in the Development of Acute Kidney Injury in a Murine Model of Remote Ischaemic Preconditioning and Liver Ischaemia Reperfusion.

Acute kidney injury (AKI) is common following liver transplantation and is associated with liver ischeamia reperfusion (IR) injury. The purpose of this study was to use a mouse model of liver IR injury and AKI to study the role of Neutrophil Gelatinase Associated Lipocalin (NGAL), a biomarker of AKI, in liver IR injury and AKI. We demonstrate an adapted, reproducible model of liver IR injury and AKI in which remote ischemic preconditioning (RIPC) by repeated episodes of hindleg ischemia prior to liver IR reduced the severity of the IR injury. In this model, serum NGAL at 2 h post reperfusion correlated with AKI development early following IR injury. This early rise in serum NGAL was associated with hepatic but not renal upregulation of NGAL mRNA, suggesting NGAL production in the liver but not the kidney in the early phase post liver IR injury.

Bicistronic vector-based procedure to measure correlative expression and bacteriostatic activity of recombinant neutrophil gelatinase-associated lipocalin

Neutrophil gelatinase-associated lipocalin (NGAL) is a component of the human innate immune system that exerts bacteriostatic effects. Recent research suggests that NGAL is also a promising biomarker for tubular damage and aids in the early diagnosis of acute kidney injury. Therefore, the development of a method to efficiently produce recombinant NGAL has considerable clinical value. This study aimed to analyze the correlation between fluorescence reporter (enhanced green fluorescent protein, EGFP) intensity and NGAL levels, mediated by a bicistronic expression system based on internal ribosome entry sites (IRESs). During the 14-day culture period, EGFP intensity was positively correlated with NGAL concentrations. The purified protein also exerted bacteriostatic effects, interfering with bacterial iron uptake machinery during periods of iron starvation. The purified NGAL was also applied to generate a standard curve that could be used for enzyme-linked immunosorbent assay of samples containing unknown NGAL quantities. In conclusion, we successfully developed a procedure using EGFP and IRES-based vector to predict NGAL production levels and optimize protein harvest time. Our approach is also a simple and effective method for evaluating bioactivity.

Association between Neutrophil Gelatinase-Associated Lipocalin and Fetal Hemoglobin Levels in Patients with Type 2 Diabetes Mellitus.

The effect of neutrophil gelatinase-associated lipocalin (NGAL) on fetal hemoglobin (HbF) levels in diabetic patients is rarely investigated. This study is aimed at investigating the possible association between NGAL and HbF levels in type 2 diabetes mellitus (T2DM). A total of 160 patients with T2DM and 61 healthy individuals were evaluated. NGAL, HbF, tumor necrosis factor-α (TNF-α), interleukin-5 (IL-5), glycated hemoglobin (HbA1c), fasting plasma glucose (FPG), and urine albumin levels were measured. HbF levels were significantly higher in patients with elevated NGAL than in those without elevated NGAL (1.44% versus 0.94%, P = 0.001). High HbF was 2.3 times more prevalent in patients with elevated NGAL than in those without elevated NGAL. In addition, NGAL, TNF-α, and IL-5 levels were significantly higher in patients with high HbF than in those with low HbF; however, there was no significant difference in HbA1c and FPG levels between the two groups. HbF was positively correlated with NGAL (r = 0.275, P < 0.001), TNF-α (r = 0.256, P < 0.001), and IL-5 (r = 0.212, P < 0.001), but not with HbA1c and FPG. An elevated NGAL level led to a 1.27-fold increase in the prevalence of high HbF (odds ratio: 1.27, 95% CI: 1.03–2.51, and P < 0.001). The diagnostic efficacy of NGAL to identify an elevated HbF level was superior to that of HbA1c (area under the curve: 0.697, 95% CI: 0.609–0.786 versus 0.584, 95% CI: 0.488–0.681, and P = 0.022). In conclusion, enhanced NGAL production may be closely linked to elevated HbF in conjunction with proinflammatory cytokines in patients with T2DM.

Expression of Secreted Neutrophil Gelatinase-Associated Lipocalin in 293T Cell Using the Inducible Dual-Function System

Neutrophil gelatinase-associated lipocalin (NGAL) has emerged as a promising biomarker for the early prediction of acute kidney injury (AKI). The production of recombinant NGAL is considered to be necessary for the development of a detection method. This study intended to express the recombinant NGAL protein in 293T cell under the Tet-On inducible system and human serum albumin signal sequence (HSA-SS). The transfection efficiency and protein modulation were assessed by detecting the expression of the enhanced green fluorescent protein (EGFP) and secreted NGAL protein. Both proteins were detected only in the presence of a doxycycline (Dox) inducer. Cell toxicity was not found under any conditions. Moreover, a higher level of soluble NGAL protein in the supernatant secreted by HSA-SS compared with a native signal peptide (Nat-SS) was observed. In summary, this work successfully optimized the conditions for induction of NGAL expression. This system will provide as an efficient strategy to produce other recombinant proteins secreted from a mammalian cell.

Neutrophil gelatinase-associated lipocalin distribution in preterm newborns without acute kidney injury as defined by a reference method

Introduction Neutrophil gelatinase-associated lipocalin (NGAL) has been proposed as an early acute kidney injury (AKI) biomarker in the neonatal population. Our goal is to describe this biomarker behavior in this high-risk population, in absence of AKI as confirmed by inulin clearance. Materials and methods Prospective study including 42 preterm newborns (mean gestational age: 30.7 ± 2.3 weeks) with a urinary NGAL collection between day 1 and 6 of life. Results Median urinary neutrophil gelatinase-associated lipocalin (uNGAL) value is 122.8 ng/ml (7–1981.5 ng/ml). Statistically significant higher uNGAL values are found in female. uNGAL median values are decreasing when comparing extremely, very, and late preterm groups (812.2 ng/ml [75.8–1453.9] vs. 124.4 ng/ml [31.4–1981.5] vs. 65.3 ng/ml [7.1–1091]). There is a statistically significant inverse correlation between gestational age and uNGAL values (Pearson’s coefficient r= −0.37). uNGAL median values are higher in groups exposed to gentamicin, neonatal asphyxia, early onset sepsis, or patent ductus arteriosus. Median inulin clearance is 18.8 ml/min/1.73 m2 [14.8–25.5 ml/min/1.73 m2]. There is no correlation between uNGAL values and inulin clearance results (Pearson’s coefficient r=–0. 29, p: .06). Conclusions In this preterm newborn’s series without AKI, the median uNGAL and its high variability are in accordance with published reference ranges. Correlation between uNGAL and gestational age exists, as well as gender impact. Newborns exposed to different renal insults present higher uNGAL values, suggesting potential undetected tubular toxicity or reflecting NGAL production in case of inflammatory or ischemic processes.

Neutrophil Gelatinase-Associated Lipocalin from immune cells is mandatory for aldosterone-induced cardiac remodeling and inflammation

Immune system activation is involved in cardiovascular (CV) inflammation and fibrosis, following activation of the mineralocorticoid receptor (MR). We previously showed that Neutrophil Gelatinase-Associated Lipocalin (NGAL) is a novel target of MR signaling in CV tissue and plays a critical role in aldosterone/MR-dependent hypertension and fibrosis. We hypothesized that the production of NGAL by immune cells may play an important part in the mediation of these deleterious mineralocorticoid-induced effects. We analyzed the effect of aldosterone on immune cell recruitment and NGAL expression in vivo. We then studied the role of NGAL produced by immune cells in aldosterone-mediated cardiac inflammation and remodeling using mice depleted for NGAL in their immune cells by bone marrow transplantation and subjected to mineralocorticoid challenge NAS (Nephrectomy, Aldosterone 200μg/kg/day, Salt 1%). NAS treatment induced the recruitment of various immune cell populations to lymph nodes (granulocytes, B lymphocytes, activated CD8+ T lymphocytes) and the induction of NGAL expression in macrophages, dendritic cells, and PBMCs. Mice depleted for NGAL in their immune cells were protected against NAS-induced cardiac remodeling and inflammation.We conclude that NGAL produced by immune cells plays a pivotal role in cardiac damage under mineralocorticoid excess. Our data further stressed a pathogenic role of NGAL in cardiac damages, besides its relevance as a biomarker of renal injury.

Interleukin-1β as a driver of renal NGAL production

Neutrophil gelatinase-associated lipocalin (NGAL) is increasingly regarded as a biomarker of acute kidney injury, or kidney injury in general, but the stimuli responsible for its production are incompletely understood. This study tested the relationship between the pro-inflammatory cytokine interleukin-1β (IL-1β) and both circulating and renal NGAL, using chronic subcutaneous infusion of IL-1β in mice and tissue culture of renal cell lines. Following a 14-day subcutaneous infusion of vehicle or IL-1β (10ng/h) in male C57Bl/6 mice, a striking positive correlation (r2=0.94; P<0.01) was observed between plasma IL-1β and NGAL concentrations. NGAL was markedly increased in the kidneys of IL-1β-infused mice compared with vehicle-treated mice, both at the protein and mRNA level, indicating increased local as well as systemic production of NGAL. Immunohistochemical staining revealed prominent increases of NGAL in the proximal tubular epithelium of IL-1β infused mice. These effects occurred in the absence of overt renal injury, with plasma creatinine concentration not significantly different between groups. Further showing that IL-1β has a direct effect on NGAL production by tubular epithelial cells, exposure of a proximal tubular cell line (HK-2 cells) and a cortical collecting duct principal cell line (mpkCCD cells) to IL-1β for 24h produced a significant increase of NGAL mRNA levels (>30-fold). These data indicate IL-1β serves as a powerful stimulus for renal production of NGAL.

0268 : Implication of the Neutrophil Gelatinase-Associated Lipocalin (NGAL) from immune cells in aldosterone induced cardiovascular remodeling

Background Inadequate activation of the Mineralocorticoid Receptor (MR) promotes hypertension, inflammation and fibrosis. Neutrophil Gelatinase- Associated Lipocalin (NGAL), a pro-inflammatory/fibrotic glycoprotein, is a direct target of the MR in cardiovascular cells, and is increased in immune cells during inflammation. Recently, we demonstrated that NGAL is crucial for the hypertensive and pro-fibrotic effects of the nephrectomy-aldosteronesalt (NAS) challenge in mice. However, the specific cell types that modulate NGAL production during aldosterone-dependent hypertension are still unknown. The aim of this study was to characterize NGAL expression in mouse immune cells, and to study the effect of MR activation on NGAL and pro-inflammatory cytokines expression in dendritic cells (DCs). Methods Male C57Bl6 mice were submitted to 28 days of NAS challenge (200μg/kg/d). CD4 + , CD8 + T cells, B cells, DCs and Macrophages (Mo) were sorted from spleen. DCs and Mo were cultured from WT and NGAL-KO mice and treated with aldosterone (100nM) for 24h. NGAL and cytokines mRNAs abundance was measured by RT-qPCR. Results NAS treatment induced a selective increase in the recruitment of activated-CD8 + cells, B cells and granulocytes in lymph nodes. NGAL abundance was higher in PBMC, DCs and Mo, and further increased in NAS mice ( In vitro MR activation by aldosterone in DCs induced an upregulation of NGAL and cytokines involved in the adaptive immune response (TGF-β1, IL-23). Interestingly, the absence of NGAL in DCs prevented this increase. Conclusion MR activation and subsequent NGAL induction in DCs could play a pivotal role in the inflammation observed during aldosterone-dependent hypertension. The author hereby declares no conflict of interest

Role of oncogene 24p3 neutrophil gelatinase-associated lipocalin (NGAL) in digestive system cancers.

Neutrophil gelatinase-associated lipocalin, known also as 24p3 lipocalin, lipocalin-2 or uterocalin (in mouse), is a small secretory protein binding small molecular weight ligands which takes part in numerous processes including apoptosis induction in leukocytes, iron transport, smell, and prostaglandins and retinol transport [19]. It was discovered in activated neutrophils as a covalent peptide associated with human gelatinase neutrophils [7]. Neutrophil lipocalin is secreted physiologically in the digestive system, respiratory tract, renal tubular cells, liver or immunity system. Systematic (circulated in plasma) neutrophil gelatinase come from multiple sources; it may be synthesized in the liver, secreted from activated neutrophils or macrophages, or derive from atherosclerosis or inflammatory endothelial cells [17]. NGAL is stored secondarily in granulates with lactoferrin, calprotectin or MAC-1, which take part in neutrophils' action and migration [13,19]. NGAL participates in acute and chronic inflammation (production of NGAL is indicated by factors conducive to cancer progression) [13,21]. NGAL levels increase in inflammatory or endothelial damage. NGAL level is measured in blood or urine. It is known as a kidney failure factor [7,20]. NGAL is therefore one of the most promising new generation biomarkers in clinical nephrology [6]. The role of NGAL in digestive system neoplasms has not been explored in detail. However, overexpression of this marker was proved in neoplasms such as esophageal carcinoma, stomach cancer, pancreatic cancer or colon cancer, which may indicate an association between concentration and neoplasm [3].

Elevated Plasma Neutrophil Gelatinase-Associated Lipocalin Level as a Risk Factor for Anemia in Patients with Systemic Inflammation.

Studies on neutrophil gelatinase-associated lipocalin (NGAL) as an iron-regulatory protein are limited. This study investigated the relationships between plasma NGAL levels and indices of anemia in 187 patients with systemic inflammation. Plasma NGAL levels were significantly higher in patients with anemia versus in patients without anemia (185 ng/mL versus 98 ng/mL; P < 0.001). Serum iron levels were lower in patients with NGAL > 156 ng/mL than in those with NGAL ≤ 156 ng/mL (27.4 ± 25.3 µg/dL versus 58.1 ± 43.5 µg/dL; P < 0.001). In a receiver operating characteristic curve, the diagnostic ability of NGAL to identify anemia was superior to that of high-sensitivity C-reactive protein [0.712 (95% CI, 0.618–0.787) versus 0.649 (95% CI, 0.573–0.744); P < 0.01]. In a multivariate logistic regression analysis, the elevated NGAL level was significantly associated with the presence of anemia after adjusting for potential confounders [odds ratio, 1.30 (95% CI, 1.07–2.58); P = 0.010]. In conclusion, enhanced NGAL production may contribute to the development of anemia in patients with systemic inflammation.

α-Amylase in Vaginal Fluid: Association With Conditions Favorable to Dominance of Lactobacillus.

Vaginal glycogen is degraded by host α-amylase and then converted to lactic acid by Lactobacilli. This maintains the vaginal pH at ≤4.5 and prevents growth of other bacteria. Therefore, host α-amylase activity may promote dominance of Lactobacilli. We evaluated whether the α-amylase level in vaginal fluid is altered in women with bacterial vaginosis (BV) and vulvovaginal candidiasis (VVC) and whether its concentration was associated with levels of lactic acid isomers and host mediators. Vaginal fluid was obtained from 43 women with BV, 50 women with VVC, and 62 women with no vulvovaginal disorders. Vaginal fluid concentrations of α-amylase, secretory leukocyte protease inhibitor (SLPI), hyaluronan, hyaluronidase-1, β-defensin, and elafin were measured by enzyme-linked immunosorbent assay (ELISA). Vaginal concentrations of neutrophil gelatinase-associated lipocalin (NGAL), matrix metalloproteinase (MMP) 8, and d- and l-lactic acid levels in these patients were previously reported. The median vaginal fluid α-amylase level was 1.83 mU/mL in control women, 1.45 mU/mL in women with VVC, and 1.07 mU/mL in women with BV. Vaginal levels of α-amylase were correlated with d-lactic acid (P = .003) but not with l-lactic acid (P > .05) and with SLPI (P < .001), hyaluronidase-1 (P < .001), NGAL (P = .001), and MMP-8 (P = .005). The exfoliation of glycogen-rich epithelial cells into the vaginal lumen by hyaluronidase-1 and MMP-8 may increase glycogen availability and promote α-amylase activity. The subsequent enhanced availability of glycogen breakdown products would favor proliferation of Lactobacilli, the primary producers of d-lactic acid in the vagina. Concomitant production of NGAL and SLPI would retard growth of BV-related bacteria.

0214 : Mineralocorticoid Receptor (MR) activation induces the expression of Neutrophil Gelatinase-Associated Lipocalin (NGAL) in dendritic cells in vitro and during the aldosterone-dependent hypertension

Inadequate activation of the Mineralocorticoid Receptor (MR) promotes hypertension, inflammation and fibrosis. Neutrophil Gelatinase- Associated Lipocalin (NGAL), a pro-inflammatory/fibrotic glycoprotein, is a target of MR-genomic upregulation in cardiovascular cells, and is increased in immune cells during inflammation. Recently, we have demonstrated that NGAL is crucial for hypertensive effects of aldosterone-salt (NAS) challenge in mice. The specific cell types that modulate the NGAL production during Aldosterone (Aldo)-dependent hypertension are unknown. The aim was to characterize the NGAL expression in mouse immune cells, and to study the effect of MR activation on the NGAL and pro-inflammatory cytokines expression in dendritic cells (DCs). Male C57Bl6 mice were treated in groups Sham and NAS (200μg/kg/d, 28 days). Peripheral blood mononuclear cells (PBMC) were isolated, and CD4 + , CD8 + T cells, B cells, DCs and Macrophages (Mø) were sorted from spleen. DCs and Mø were cultured from WT and NGAL-KO mice and treated with Aldo (100nM) or vehicle for 24hrs. NGAL and cytokines mRNAs abundance was measured by qRT-PCR. NAS mice presented high systolic blood pressure (123 mmHg vs. Sham 101±6 mmHg, p<0.05), cardiac and renal hypertrophy. Additionally, NAS treatment induced a selective increase in the recruitment of activated- CD8 + cells, B cells and granulocytes in lymph nodes. NGAL abundance was higher in PBMC, DCs and Mø, which were further increased in NAS mice (<3-fold vs. Sham, p<0.05 mRNA). In vitro MR activation by Aldo in DCs, but not in Mø, induced an upregulation of NGAL and of cytokines involved in the adaptive immune response: TGF-β1 and IL-23p19 (n=4, p<0.05). Interestingly, the NGAL absence in DCs prevented this overexpression. The MR activation and their subsequent NGAL induction in DCs could play a pivotal role in the inflammation observed during the Aldodependent hypertension.

Blockade of recombinant human IL-6 by tocilizumab suppresses matrix metalloproteinase-9 production in the C28/I2 immortalized human chondrocyte cell line.

Two immortalized human juvenile chondrocyte cell lines, T/C28a2 and C28/I2, were employed to determine the extent to which recombinant human (rh) IL-6 or rh-TNF-α increased the production of matrix metalloproteinase-9 (MMP-9). The effect of rhIL-6 on neutrophil gelatinase-associated lipocalin (NGAL) was also assessed. Although C28/I2 chondrocytes incubated with rhIL-6 (50 ng/ml) increased MMP-9 production which could not be mimicked by the T/C28a2 chondrocyte line, the effect of rhTNF-α on MMP-9 was more robust than with rhIL-6. The combinations of rhIL-6 and soluble IL-6 receptor-α (sIL-6Rα) or rhIL-6 and tocilizumab (TCZ), a fully-humanized recombinant monoclonal antibody that neutralizes the interaction between IL-6 and IL-6R significantly reduced MMP-9 production by C28/I2 chondrocytes. However, TCZ had no effect on rhTNF-α-induced MMP-9 production. By contrast, rhIL-6 did not increase the production of NGAL by C28/I2 chondrocytes although the number of NGAL-positive cells was significantly reduced by sIL-6R compared to its control group, but not by the combination of rhIL-6 plus TCZ compared to rhIL-6. In summary, these results showed that rhIL-6 stimulated the production of MMP-9, but not NGAL, in the C28/I2 chondrocyte line. TCZ or sIL-6Rα suppressed rhIL-6-induced MMP-9 production.

Plasma Neutrophil Gelatinase Associated Lipocalin in Neonates With and Without Sepsis

Background: Plasma neutrophil gelatinase associated lipocalin (NGAL) level is increased in sepsis irrespective of renal dysfunction. We investigated the effect of sepsis on the plasma level of NGAL in neonates. Objectives: The aim of this study was to find whether serum NGAL is a reliable marker for early diagnosis of sepsis in neonates. Patients and Methods: We conducted a prospective observational study in a university hospital neonatal intensive care unit. Serum NGAL was measured in 120 neonates admitted to the neonatal intensive care unit. Neonates were classified according to the presence of sepsis. Fifty-two Patients had sepsis. Results: The NGAL levels were significantly higher in septic neonates compared with non-septic neonates (102.9 ± 69.9 ng/mL versus 29.2 ± 13.3 ng/mL, P value = 0.0001). An optimal cut off-point of 48 ng/mL for serum NGAL could potentially detect neonates with sepsis with a sensitivity and specificity of 92% and 91%, respectively. Conclusions: Sepsis enhances the production of plasma NGAL in critically ill neonates. Thus Plasma NGAL can help clinicians diagnose sepsis in critically ill neonates during early phases.

Neutrophil Gelatinase-Associated Lipocalin Levels in Patients with Thalassemia and Sickle Cell Disease: Correlation with Renal Injury

Background and Aims: Neutrophil gelatinase-associated lipocalin (NGAL) is a protein belonging to the lipocalin superfamily initially found in activated neutrophils, in accordance with its role as an innate antibacterial factor. However, it subsequently was shown that many other types of cells, including in the kidney tubule, may produce NGAL in response to various injuries. The increase in NGAL production and release from tubular cells after harmful stimuli of various kinds may have self-defensive intent based on the activation of specific iron-dependent pathways, which in all probability also represent the mechanism through which NGAL promotes kidney growth and differentiation. NGAL levels clearly correlate with severity of renal impairment, probably expressing the degree of active damage underlying the chronic condition. For all these reasons, NGAL may become one of the most promising next-generation biomarkers in clinical nephrology and beyond. We aimed to investigate the clinical significance of NGAL levels and its correlation with renal function in patients with hemoglobinopathies.Patients and Methods: 117 adult patients with hemoglobinopathies were included in the study divided in 3 groups. Group A: 30 patients with transfusion-dependent thalassemia major (TM); Group B: 29 patients with Non-Transfusion-Dependent Thalassemia (TI) and Group C: 58 patients with HbS/βthal disease, while 20 apparently healthy individuals served as controls (Group D). In patients and controls along with standard blood and urine chemistry. Measurements of serum Cystatin C and NGAL were performed by means of immunonephelometric and immunoenzymatic techniques, (Siemens Healthcare Diagnostics, Liederbach, Germany and R&D Systems, Minneapolis, MN, USA), respectively. Estimated Glomerular Filtration Rate (eGFR) values were calculated with an unadjusted for body surface Cystatin C based equation: eGFR (mL/min)=77.24(Cys C)-1.2623.Results: The main results of the study showed that: a) NGAL levels were significantly higher in all the groups of patients compared to controls: Group A 95.0±45.0µg/L, Group B 139.1±86.1µg/L, Group C 117.8±37.3µg/L vs Group D 50.3±11.3µg/L (p<0.001), b) Cystatin C levels were significantly higher in patients of Group A 0.94±0.34mg/L and Group C 1.04±0.50mg/L compared to controls 0.75±0.09mg/L (p<0.01), while no significant difference was found between Group B 0.72±0.13mg/L and controls (p>0.300), c) NGAL levels and eGFR values (Group A: 96.9±39.8, Group B: 117.0±26.0, Group C: 86.2±27.8 and group D: 109.6±15.0mL/min, respectively) correlated significantly in patients of Group A and Group C (r=-0.739, p<0.001 and r=-0.735, p<0.001, respectively), while NGAL values are independent from eGFR values in patients of Group B.Conclusions: These findings illustrate the tubular-glomerular activation feedback mirrored by NGAL in patients with transfusion-dependent thalassemia major and HbS/βthal disease, who suffer from renal injuries, indicating that tubular damage precedes GFR reduction. Upregulation of NGAL in patients with non-transfusion-dependent thalassemia independently of renal injuries may reflect the compensatory, protective role of NGAL in response to diverse cellular stresses, including inflammation and oxidative stress. However, recent reports have implicated NGAL upregulation as a mechanism that contributes to anemia in the setting of chronic low grade inflammation. In experimental models, systemic and medullary NGAL has been demonstrated to induce inhibition of erythropoiesis through induction of apoptosis and arrest of differentiation of erythroid progenitor cells. DisclosuresNo relevant conflicts of interest to declare.

The plasma level and biomarker value of neutrophil gelatinase-associated lipocalin in critically ill patients with acute kidney injury are not affected by continuous venovenous hemofiltration and anticoagulation applied.

IntroductionNeutrophil gelatinase-associated lipocalin (NGAL) is a biomarker of acute kidney injury (AKI), and levels reflect severity of disease in critically ill patients. However, continuous venovenous hemofiltration (CVVH) may affect plasma levels by clearance or release of NGAL by activated neutrophils in the filter, dependent on the anticoagulation regimen applied. We therefore studied handling of NGAL by CVVH in patients with AKI.MethodsImmediately before initiation of CVVH, prefilter blood was drawn. After 10, 60, 180, and 720 minutes of CVVH, samples were collected from pre- and postfilter (in- and outlet) blood and ultrafiltrate. CVVH with the following anticoagulation regimens was studied: no anticoagulation in case of a high bleeding tendency (n = 13), unfractionated heparin (n = 8), or trisodium citrate (n = 21). NGAL levels were determined with enzyme-linked immunosorbent assay (ELISA).ResultsConcentrations of NGAL at inlet and outlet were similar, and concentrations did not change over time in any of the anticoagulation groups; thus no net removal or production of NGAL occurred. Concentrations of NGAL at inlet correlated with disease severity at initiation of CVVH and at the end of a CVVH run. Concentrations of NGAL in the ultrafiltrate were lower with citrate-based CVVH (P = 0.03) and decreased over time, irrespective of anticoagulation administered (P < 0.001). The sieving coefficient and clearance of NGAL were low and decreased over time (P < 0.001).ConclusionsThe plasma level and biomarker value of NGAL in critically ill patients with AKI are not affected by CVVH, because clearance by the filter was low. Furthermore, no evidence exists for intrafilter release of NGAL by neutrophils, irrespective of the anticoagulation method applied.

Neutrophil gelatinase‐associated lipocalin and end‐stage renal disease: it is not all about the kidneys!

Neutrophil gelatinase-associated lipocalin (NGAL) is a powerful biomarker for the early detection of acute kidney injury. However, recent data suggest that NGAL also plays an important role in chronic kidney disease (CKD), reflecting the level of acute kidney damage within the CKD condition. To study whether elevated NGAL levels in CKD are a consequence of damaged tubular cells or rather due to extrarenal production, we investigated NGAL levels in anephric patients on dialysis. Plasma NGAL levels were investigated in 14 dialysis patients who underwent bilateral nephrectomy (anephric group), 18 anuric dialysis patients with remaining kidneys (dialysis group) and 12 healthy patients (healthy group). Plasma NGAL levels were significantly lower in the healthy group compared with the anephric group (143 vs. 981ng/mL; P<0·001) or the dialysis group (143 vs. 838ng/mL; P<0·001), respectively. However, NGAL levels did not differ between the anephric group and the dialysis group (981 vs. 838ng/mL; P=0·19). Assuming that NGAL is highly expressed in chronically damaged kidneys due to tubular stress, there should be significantly less NGAL in anephric patients compared with anuric dialysis patients with remaining kidneys. In contrast to this hypothesis, we found no difference in NGAL expression between these two groups, proving the entire extrarenal NGAL production in anephric patients and suggesting that the tubular NGAL expression seems to be negligible in anuric dialysis patients.

Betulinic acid suppresses NGAL-induced epithelial-to-mesenchymal transition in melanoma

Betulinic acid (BA) exhibits antitumoral activity by blocking proliferation, invasion, and angiogenesis. However, the impact of BA on epithelial-to-mesenchymal transition (EMT), a hallmark of cancer metastasis induced among others by neutrophil gelatinase-associated lipocalin (NGAL), remains unknown. The present study aimed at determining the effect of BA on NGAL-induced EMT. In A375 melanoma cells, BA downregulated mesenchymal markers, increased epithelial markers, and inhibited cytoskeletal reorganization. In addition, BA limited endogenous NGAL production and further suppressed EMT induced by exogenously added NGAL and the corresponding invasive cellular phenotype. In conclusion, BA interferes with EMT-associated changes, a mechanism to antagonize invasive melanoma cells.

Interleukin-10-Induced Neutrophil Gelatinase-Associated Lipocalin Production in Macrophages with Consequences for Tumor Growth

Tumor cell-derived factors, such as interleukin 10 (IL-10), polarize macrophages toward a regulatory M2 phenotype, characterized by the expression of anti-inflammatory cytokines and protumorigenic mediators. Here we explored molecular mechanisms allowing IL-10 to upregulate the protumorigenic protein NGAL in primary human macrophages. Reporter assays of full-length or deletion constructs of the NGAL promoter provided evidence that NGAL production is STAT3 dependent, activated downstream of the IL-10-Janus kinase (Jak) axis, as well as being C/EBPβ dependent. The involvement of STAT3 and C/EBPβ was shown by chromatin immunoprecipitation (ChIP) and ChIP-Western analysis, as well as decoy oligonucleotides scavenging both STAT3 and C/EBPβ in human macrophages. Furthermore, the production of NGAL in macrophages in response to IL-10 induces cellular growth and proliferation of MCF-7 breast cancer cells. We conclude that both STAT3 and C/EBPβ are needed to elicit IL-10-mediated NGAL expression in primary human macrophages. Macrophage-secreted NGAL shapes the protumorigenic macrophage phenotype to promote growth of MCF-7 breast cancer cells. Our data point to a macrophage-dependent IL-10-STAT3-NGAL axis that might contribute to tumor progression.

Neutrophil gelatinase-associated lipocalin as a marker of tubular damage appears to be unrelated to fractional excretion of sodium as a marker of tubular function in septic patients, with or without AKI

The utility of urinary biochemistry has recently been challenged [1], while there is emerging evidence that renal biomarkers may accurately quantify the risk of development of acute kidney injury (AKI) [2]. Neutrophil gelatinase-associated lipocalin (NGAL) is a marker of renal tubular damage [3]. Fractional excretion of sodium (FENa) is a marker of renal tubular function, and is a significantly cheaper investigation [4]. Insults damaging the tubules and resulting in AKI should both stimulate NGAL production and prevent resorption of sodium. Given the different pathological mechanisms underlying septic and nonseptic AKI, it is plausible that the relationship between these variables could be different in these two groups of patients [5].