Neutrophil Gelatinase-Associated Lipocalin: Biological Aspects and Potential Diagnostic Use in Acute Kidney Injury

Acute kidney injury (AKI) is a syndrome characterized by a rise in creatinine or a decrease in urinary flow, according to the Kidney Disease Improving Global Outcomes (KDIGO) definition. It is diagnosed in 15% of inpatients and 50% of patients in the intensive care unit (ICU), and it is related to increased mortality. As part of a global effort aimed at the elimination of preventable deaths from AKI, there is a growing interest in identifying biomarkers that can be point-of-care and that are not influenced by the variability in patient characteristics in a relevant way. Neutrophil gelatinase-associated lipocalin (NGAL), particularly in its 25 kDa form, which is exclusively released by renal tubules, has emerged as a promising biomarker with potential use in the diagnosis of AKI in the critically ill, including its use in guiding the initiation and/or weaning of renal replacement therapy (RRT). The objective of this review is to summarize the current understanding of NGAL in acute settings, emphasizing biological and genomic insights.

Temporary bilateral clamping of renal arteries induces ischemia-reperfusion: A new pig model of acute kidney injury using total intravenous anesthesia

Ischemia-reperfusion (IR) is a leading cause of acute kidney injury (AKI), and pigs are commonly used in preclinical AKI models. However, existing models often vary in the methods used to induce ischemia, and the resulting AKI tends to be mild-to-moderate. Moreover, follow-up is often performed under volatile anesthesia, which, in contrast to total intravenous anesthesia (TIVA), can induce malignant hyperthermia and cause hemodynamic instability. Here we present a novel surgical model of IR-induced AKI using bilateral renal artery clamping under TIVA. Anesthesia was induced via TIVA with diazepam, ketamine, and morphine. After retroperitoneal exposure, the renal arteries were isolated and clamped with a plastic tube for 90 min, followed by 8 h of reperfusion. The IR group (n = 6) was compared with a Sham group (n = 5) that underwent the same procedure without IR. The IR group developed moderate-to-severe AKI as evidenced by reduced glomerular filtration, a 158% increase in plasma creatinine versus 21% in the Sham group, and elevated neutrophil gelatinase-associated lipocalin levels (+280% in IR vs. 0% in Sham), indicating tubular injury. Histopathology confirmed these findings. Thus, this preclinical model successfully induced moderate-to-severe AKI in pigs. The TIVA anesthetic protocol offered several advantages compared to halogenated gas anesthesia.

Urinary neutrophil gelatinase-associated lipocalin as early biomarker for renal disease in dogs with leishmaniosis

Canine leishmaniosis (CanL), caused by Leishmania sp., presents a wide array of symptoms; renal dysfunction is frequently observed in these dogs and is associated with a poor prognosis and increased mortality. The traditional biomarkers namely urea and creatinine can detect renal damage but only in advanced stages of the disease. However, it has been shown that the symmetric dimethylarginine assay (SDMA) or the protein/creatinine ratio (UPC) and are early biomarkers of renal dysfunction. Their elevation occurs earlier than that of creatinine, but other novel biomarkers such as neutrophil gelatinase-associated lipocalin (NGAL) are currently under investigation. Our objective was to determine whether the urine NGAL-creatinine ratio (uNGAL/c) can provide very early diagnosis of kidney disease in CanL. In total, 68 dogs were included in the study: 15 healthy dogs and 53 dogs with CanL who were classified according to International Renal Interest Society (IRIS) classification: IRIS 1 (N= 34), IRIS 2 (N= 9) and IRIS 3/4 (N= 10). IRIS 1 was subdivided according to proteinuria in IRIS 1NP (13 dogs with UPC < 0.2), IRIS 1BL (8 dogs with UPC = 0.2-0.5) and IRIS 1 P (13 dogs with UPC > 0.5). Blood samples were collected for complete hematological and biochemistry analysis including plasma NGAL. Urinalysis included specific gravity, UPC, CysC and NGAL expressed as a ratio with creatinine. The mean concentrations of pCysC and SDMA in CanL, show a statistically significant increase from IRIS 1NP, not being statistically significant for pCysC in the IRIS 1BL group. The UPC show a statistically significant increase from IRIS 1NP. In all groups with CanL for uCysC/c and uNGAL/c was observed a statistically significant increase. The uNGAL/c in the group proteinuric animals, presents a positive correlation with all renal biomarkers studied. In the group of non-proteinuric animals, the uNGAL/c presents a positive correlation with SDMA and UPC. The uNGAL/c can be considered a reliable indicator of renal disease in dogs diagnosed with CanL who are non-azotemic and non-proteinuric.

Bioactive-Loaded Hydrogels Based on Bacterial Nanocellulose, Chitosan, and Poloxamer for Rebalancing Vaginal Microbiota

Biocompatible drug-delivery systems for soft tissue applications are of high interest for the medical and pharmaceutical fields. The subject of this research is the development of hydrogels loaded with bioactive compounds (inulin, thyme essential oil, hydro-glycero-alcoholic extract of Vitis vinifera, Opuntia ficus-indica powder, lactic acid, citric acid) in order to support the vaginal microbiota homeostasis. The nanofibrillar phyto-hydrogel systems developed using the biocompatible polymers chitosan (CS), never-dried bacterial nanocellulose (NDBNC), and Poloxamer 407 (PX) incorporated the water-soluble bioactive components in the NDBNC hydrophilic fraction and the hydrophobic components in the hydrophobic core of the PX fraction. Two NDBNC-PX hydrogels and one NDBNC-PX-CS hydrogel were structurally and physical-chemically characterized using Fourier-transform infrared (FTIR) spectroscopy, X-ray diffraction (XRD), transmission electron microscopy (TEM), and rheology. The hydrogels were also evaluated in terms of thermo-responsive properties, mucoadhesion, biocompatibility, and prebiotic and antimicrobial effects. The mucin binding efficiency of hydrogel base systems was determined by the periodic acid/Schiff base (PAS) assay. Biocompatibility of hydrogel systems was determined by the MTT test using mouse fibroblasts. The prebiotic activity was determined using the probiotic strains Limosilactobacillus reuteri and Lactiplantibacillus plantarum subsp. plantarum. Antimicrobial activity was also assessed using relevant microbial strains, respectively, E. coli and C. albicans. TEM evidenced PX micelles of around 20 nm on NDBNC nanofibrils. The FTIR and XRD analyses revealed that the binary hydrogels are dominated by PX signals, and that the ternary hydrogel is dominated by CS, with additional particular fingerprints for the biocompounds and the hydrogel interaction with mucin. Rheology evidenced the gel transition temperatures of 18-22 °C for the binary hydrogels with thixotropic behavior and, respectively, no gel transition, with rheopectic behavior for the ternary hydrogel. The adhesion energies of the binary and ternary hydrogels were evaluated to be around 1.2 J/m2 and 9.1 J/m2, respectively. The hydrogels exhibited a high degree of biocompatibility, with the potential to support cell proliferation and also to promote the growth of lactobacilli. The hydrogel systems also presented significant antimicrobial and antibiofilm activity.

Advances in understanding and treating diabetic kidney disease: focus on tubulointerstitial inflammation mechanisms

Diabetic kidney disease (DKD) is a serious complication of diabetes that can lead to end-stage kidney disease. Despite its significant impact, most research has concentrated on the glomerulus, with little attention paid to the tubulointerstitial region, which accounts for the majority of the kidney volume. DKD's tubulointerstitial lesions are characterized by inflammation, fibrosis, and loss of kidney function, and recent studies indicate that these lesions may occur earlier than glomerular lesions. Evidence has shown that inflammatory mechanisms in the tubulointerstitium play a critical role in the development and progression of these lesions. Apart from the renin-angiotensin-aldosterone blockade, Sodium-Glucose Linked Transporter-2(SGLT-2) inhibitors and new types of mineralocorticoid receptor antagonists have emerged as effective ways to treat DKD. Moreover, researchers have proposed potential targeted therapies, such as inhibiting pro-inflammatory cytokines and modulating T cells and macrophages, among others. These therapies have demonstrated promising results in preclinical studies and clinical trials, suggesting their potential to treat DKD-induced tubulointerstitial lesions effectively. Understanding the immune-inflammatory mechanisms underlying DKD-induced tubulointerstitial lesions and developing targeted therapies could significantly improve the treatment and management of DKD. This review summarizes the latest advances in this field, highlighting the importance of focusing on tubulointerstitial inflammation mechanisms to improve DKD outcomes.

Whetting the Rapid Diagnostic Tools for Sepsis

How to cite this article: Krishna B. Whetting the Rapid Diagnostic Tools for Sepsis. Indian J Crit Care Med 2023;27(3):159-160.

Urine neutrophil gelatinase-associated lipocalin as a biomarker of acute kidney injury and prognosis in decompensated chronic liver disease: A prospective study

BACKGROUND

Acute kidney injury (AKI) heralds deterioration in patients with decompensated chronic liver disease (DCLD). Serum creatinine (sCr), a component of the model for end-stage liver disease-sodium (MELD-Na) prognostic score, has limitations in patients with DCLD. We evaluated the prognostic role of urine neutrophil gelatinase-associated lipocalin (NGAL) in DCLD and its ability to sub-type AKI.

METHODS

Total 147 consecutive patients hospitalized between June 2018 and June 2020 for complications of DCLD were evaluated. Urine NGAL was estimated and demographic, clinical and biochemical parameters recorded at baseline. Participants were followed up till the end of study period or mortality, whichever came earlier. Primary outcomes included all-cause mortality and time to death after index hospitalization. Secondary outcomes included the presence and type of AKI, need for intensive care unit (ICU) stay, length of ICU/hospital stay, in-hospital mortality, development of new-onset/recurrent AKI and recurrent hospitalization after index admission.

RESULTS

Urine NGAL was highest in acute tubular necrosis (ATN), lowest in pre-renal azotemia (PRA) and intermediate in hepatorenal syndrome (HRS-AKI). Urine NGAL (p = 0.0208) was superior to sCr (p = 0.0388) and inferior to fractionated excretion of sodium (FENa) (p = 0.0013) in stratifying AKI. A cut-off of 203.9 ng/mL discriminated between HRS and PRA with sensitivity 77.8% and specificity 68.7%. Urine NGAL correlated with MELD-Na score, need for ICU stay, in-hospital mortality and mortality at three and six months. Two-year survival was significantly lower in patients with urine NGAL > 205 ng/mL. Addition of log-urine-NGAL score did not improve predictive performance of MELD-Na.

CONCLUSION

Urine NGAL could identify AKI sub-types and correlated with short-term clinical outcomes, including mortality.

Serum neutrophil gelatinase-associated lipocalin as a potential biomarker for cognitive decline in spinal cord injury

Objective

Neutrophil gelatinase-associated lipoprotein (NGAL), a protein encoded by the lipocalcin-2 (LCN2) gene, has been reported to be involved in multiple processes of innate immunity, but its relationship with spinal cord injury (SCI) remains unclear. This study set out to determine whether NGAL played a role in the development of cognitive impairment following SCI.

Methods

At the Neck-Shoulder and Lumbocrural Pain Hospital, a total of 100 SCI patients and 72 controls were enrolled in the study through recruitment. Through questionnaires, baseline data on the participants' age, gender, education level, lifestyle choices (drinking and smoking) and underlying illnesses (hypertension, diabetes, coronary heart disease, and hyperlipidemia) were gathered. The individuals' cognitive performance was evaluated using the Montreal Cognitive Scale (MoCA), and their serum NGAL levels were discovered using ELISA.

Results

The investigation included 72 controls and 100 SCI patients. The baseline data did not differ substantially between the two groups, however the SCI group's serum NGAL level was higher than the control group's (p < 0.05), and this elevated level was adversely connected with the MoCA score (p < 0.05). According to the results of the ROC analysis, NGAL had a sensitivity of 58.24% and a specificity of 86.72% for predicting cognitive impairment following SCI.

Conclusions

The changes in serum NGAL level could serve as a biomarker for cognitive impairment in SCI patients, and this holds true even after taking in account several confounding variables.

Slowly Relaxing Local Structure Analysis of 15N Relaxation from the Proteins p50 and Human Neutrophil Gelatinase-Associated Lipocalin: New Insights into the Dynamic Structure of β-Barrel Proteins

Nuclear magnetic resonance relaxation analysis is a powerful method for studying the internal mobility of proteins. We have developed for analysis the slowly relaxing local structure (SRLS) approach. SRLS is general in its nature in several respects, including the tensorial representation of the physical quantities comprising the dynamic model. By controlling tensor symmetry, a broad range of systems can be treated with physical relevance, typically with data-fitting techniques. In simple limits, SRLS yields the traditional model-free (MF) method. In the present context, MF simplicity means featuring the highest possible tensor symmetry. This renders MF-based data-fitting susceptible to the usage of fit parameters, yielding physically ill-defined results. A typical candidate is the R_ex term, devised to represent ms-μs motions but often invoked by the fitting scheme just to improve the statistics. Here, we consider two such cases using the N-H bond as probe and the proteins p50 and human neutrophil gelatinase-associated lipocalin as paradigm systems. We illustrate the harm caused by the physically unjustified involvement of R_ex in MF-based ¹⁵N relaxation analysis. Then, we show that forgoing the usage of R_ex, SRLS analysis of the very same experimental data provides interesting new information.

The Most Promising Biomarkers of Allogeneic Kidney Transplant Rejection

Clinical transplantology is a constantly evolving field of medicine. Kidney transplantation has become standard clinical practice, and it has a significant impact on reducing mortality and improving the quality of life of patients. Allogenic transplantation induces an immune response, which may lead to the rejection of the transplanted organ. The gold standard for evaluating rejection of the transplanted kidney by the recipient's organism is a biopsy of this organ. However, due to the high invasiveness of this procedure, alternative diagnostic methods are being sought. Therefore, the biomarkers may play an essential predictive role in transplant rejection. A review of the most promising biomarkers for early diagnosis and prognosis prediction of allogenic kidney transplant rejection summarizes novel data on neutrophil gelatinase-associated lipocalin (NGAL), kidney injury molecule-1 (KIM-1), C-X-C motif chemokine 10 (CXCL-10), cystatin C (CysC), osteopontin (OPN), and clusterin (CLU) and analyses the dynamics of changes of the biomarkers mentioned above in kidney diseases and the mechanism of rejection of the transplanted kidney.

Neutrophil Gelatinase-Associated Lipocalin (NGAL) in Peritoneal Dialytic Effluent: Preliminary Results on the Comparison between Two Different Methods in Patients with and without Peritonitis

Neutrophil gelatinase-associated lipocalin (NGAL) is a lipocalin involved in the immune response and is significantly high in the peritoneal dialytic effluent (PDE) of peritoneal dialysis (PD) patients with inflammation of the peritoneum membrane (peritonitis). The focus of this study was to match two different techniques for peritoneal NGAL evaluation: NGAL point-of-care test-POCT (NGAL Dipstick—NGALds) versus the laboratory-based NGAL assay and with the white cell count in PDE. In this study, we included 30 PD patients: 17 with peritonitis and 13 without. Peritoneal NGAL was tested by a turbidimetric immunoassay and by NGALds. We noticed a good positive linear correlation between the POCT results and the laboratory-based test and between the peritoneal NGALds and white cell count in PDE (both, p < 0.01). NGALds values resulted in being elevated in patients with peritonitis (300 ng/mL, IQR 300–600) in comparison to patients without (100 ng/mL, IQR 50–150) (p < 0.01). Furthermore, the NGALds test was performed in a median time of 20 mins (IQR 18–21) in comparison with the median time of 65 mins (IQR 55–69) necessary for the laboratory-based test (p < 0.01). The results of the NGALds were coherent with the laboratory-based NGAL and with the white cell count in PDE; furthermore, it was a user-friendly method with real-time findings. NGALds could be an extra tool for the diagnosis of peritonitis, helpful at the bedside of the patient, shortening the length of diagnosis, and if the laboratory-based NGAL test is not accessible.

Relation of Neutrophil Gelatinase-Associated Lipocalin Overexpression to the Resistance to Apoptosis of Tumor B Cells in Chronic Lymphocytic Leukemia

The resistance to apoptosis of chronic lymphocytic leukemia (CLL) cells partly results from the deregulated production of survival signals from leukemic cells. Despite the development of new therapies in CLL, drug resistance and disease relapse still occur. Recently, neutrophil gelatinase-associated lipocalin (NGAL), a secreted glycoprotein, has been suggested to have a critical role in the biology of tumors. Thus, we investigated the relevance of NGAL in CLL pathogenesis, analyzed the expression of its cellular receptor (NGAL-R) on malignant B cells and tested whether CLL cells are resistant to apoptosis through an autocrine process involving NGAL and NGAL-R. We observed that NGAL concentrations were elevated in the serum of CLL patients at diagnosis. After treatment (and regardless of the therapeutic regimen), serum NGAL levels normalized in CLL patients in remission but not in relapsed patients. In parallel, NGAL and NGAL-R were upregulated in leukemic cells from untreated CLL patients when compared to normal peripheral blood mononuclear cells (PBMCs), and returned to basal levels in PBMCs from patients in remission. Cultured CLL cells released endogenous NGAL. Anti-NGAL-R antibodies enhanced NGAL-R⁺ leukemia cell death. Conversely, recombinant NGAL protected NGAL-R⁺ CLL cells against apoptosis by activating a STAT3/Mcl-1 signaling pathway. Our results suggest that NGAL and NGAL-R, overexpressed in untreated CLL, participate in the deregulation of the apoptotic machinery in CLL cells, and may be potential therapeutic clues for CLL treatment.

Prognostic value of dynamic plasma endostatin for the prediction of mortality in acute kidney injury: A prospective cohort study

Objective

The aim of the current study was to evaluate the value of plasma endostatin for predicting 30-day mortality of patients with acute kidney injury (AKI).

Methods

Patients who underwent non-cardiac major surgery and developed AKI in the first 48 hours after admission to the intensive care unit were consecutively included. Concentrations of plasma neutrophil gelatinase-associated lipocalin (NGAL), cystatin C (Cys C), and endostatin were measured at three time points: 0, 24, and 48 hours after the AKI diagnosis. Clinical patient characteristics were recorded after AKI was diagnosed.

Results

A total of 256 new-onset AKI patients were enrolled. Of these, 48 (18.7%) patients died within 30 days. The difference in plasma endostatin values between 0 and 24 hours (ΔEndostatin-24h) yielded the best area under the curve (AUC) of 0.747 for predicting 30-day mortality in AKI patients; NGAL and Cys C achieved AUC of 0.672 and 0.647, respectively. The predictive AUC increased to 0.833 when ΔEndostatin-24h was combined with sequential organ failure assessment score and AKI classification.

Conclusion

Dynamic plasma endostatin is useful for predicting 30-day mortality in AKI patients. The predictive power of dynamic plasma endostatin can be significantly improved when it is combined with clinical patient data.

Urine neutrophil gelatinase-associated lipocalin to diagnose and characterize acute kidney injury in dogs

BACKGROUND

Urine neutrophil gelatinase-associated lipocalin (NGAL) is a promising biomarker of acute kidney injury (AKI) in dogs.

OBJECTIVES

To evaluate the utility of urinary NGAL for characterizing AKI according to volume responsiveness, presence of inflammation and sepsis, and prognosis.

ANIMALS

Dogs with AKI (n = 76) and healthy controls (n = 10).

METHODS

Prospective study. Clinical and clinicopathologic data including absolute urine NGAL concentration (uNGAL) and NGAL normalized to urine creatinine concentration (uNGALC) were measured upon admission. Dogs were graded according to International Renal Interest Society (IRIS) AKI guidelines and compared based on AKI features: volume-responsive (VR-) AKI vs. intrinsic (I-) AKI based on IRIS criteria; VR-AKI and I-AKI based on urine chemistry; inflammatory versus noninflammatory; septic versus nonseptic; and survivors versus nonsurvivors. Nonparametric statistics were calculated, and significance set at P < .05.

RESULTS

Urinary NGAL was significantly higher in dogs with AKI compared to controls, regardless of AKI grade. Urinary NGAL did not differ between dogs with VR-AKI and I-AKI based on IRIS criteria, whereas higher uNGALC was recorded in dogs with I-AKI based on urine chemistry. Urinary NGAL was significantly higher in dogs with inflammatory AKI, whereas no difference with respect to sepsis or outcome was identified.

CONCLUSIONS AND CLINICAL IMPORTANCE

Urinary NGAL is a sensitive marker for AKI in dogs, but its specificity is affected by systemic inflammation. Increased urinary NGAL in both I-AKI and VR-AKI also suggests the presence of tubular damage in transient AKI. Combining urine chemistry data with IRIS criteria could facilitate AKI characterization in dogs.

Fluid resuscitation with preventive peritoneal dialysis attenuates crush injury-related acute kidney injury and improves survival outcome

Background

In-hospital renal replacement therapy (RRT) is widely used for the treatments of acute kidney injury (AKI) in crush injury (CI) victims. This study was designed to investigate whether preventive peritoneal dialysis (PPD) is useful for renal protection in CI.

Methods

Animals received hindlimb compressions for 6 h to induce CI. Then, animals were untreated or treated with PPD and/or massive fluid resuscitation (MFR) for 8 h since the onset of compression release. Blood and renal tissue samples were collected at various time points for biological and morphological analysis.

Results

PPD attenuated lactic acidosis and reduced serum K⁺ and myoglobin levels in CI animals. In addition, PPD was effective in removing blood urea nitrogen (BUN) and creatinine, and reduced renal expressions of neutrophil gelatinase-associated lipocalin (NGAL). The combination of PPD and MFR furtherly attenuated AKI with significantly decreased histological scores (p = 0.037) and reduced NGAL expressions (p = 0.0002) as compared with the MFR group. Moreover, MFR + PPD group had a significantly higher survival rate than that in the MFR and the PPD groups (p < 0.05, respectively).

Conclusion

The use of PPD at the onset of compression release is beneficial for renal protection and survival outcome in a rabbit model of CI.

Electronic supplementary material

The online version of this article (10.1186/s13049-019-0644-0) contains supplementary material, which is available to authorized users.

Urinary versus plasma neutrophil gelatinase-associated lipocalin (NGAL) as a predictor of mortality for acute kidney injury in intensive care unit patients

OBJECTIVE

To examine urinary and plasma neutrophil gelatinase-associated lipocalin (NGAL) levels in predicting ICU mortality.

DESIGN

Prospective observational.

SETTING

University Critical Care setting.

PARTICIPANTS

50 patients with acute kidney injury (AKI).

INTERVENTIONS

None.

MEASUREMENTS AND MAIN RESULTS

Serial urinary and plasma concentrations of NGAL were measured. Twenty-five patients had early progression (EP) and 25 patients had early improvement (EI) of AKI. Plasma concentrations of NGAL in the EP group (N=25) were significantly higher than those in the EI group (129 [IQR; 20] vs. 111 [IQR; 32] ng/mL; P=0.009), while urine NGAL levels on admission were similar in both groups (61 [IQR; 20] vs. 65 [IQR; 20] ng/mL; P=0.767). Plasma NGAL concentrations rapidly decreased to 87 [32] ng/mL in the EI group (P<0.001) and while it remained elevated in the EP group (138 [21] ng/mL). Within 28-days, 50% of the patients died in the EP group, whereas no patient died in the EI group (P<0.001). Plasma NGAL was a fair predictor for progression of AKI (AUC; 0.719±0.063; P=0.006). 48-hour changes in plasma NGAL levels predicted death within 28-days of ICU admission (AUC; 0.874±0.048; P<0.001).

CONCLUSION

Early progression of AKI was associated with more death within 28 and 90days. While one time measurement of plasma NGAL levels at the time ICU admission may represent the kidney health status in critical care settings, it does not reliably predict mortality. On the other hand, changes in plasma NGAL within 48h of admission improve the value of this biomarker in predicting ICU mortality.

Revisiting Neutrophil Gelatinase-Associated Lipocalin (NGAL) in Cancer: Saint or Sinner?

Human neutrophil gelatinase-associated lipocalin (NGAL) is a glycoprotein present in a wide variety of tissues and cell types. NGAL exists as a 25 kDa monomer, a 46 kDa homodimer (the most abundant form in healthy subjects) and a 130 kDa disulfide-linked heterodimer bound to latent matrix metalloproteinase-9. Dysregulated expression of NGAL in human malignancies suggests its value as a clinical marker. A growing body of evidence is highlighting NGAL’s paradoxical (i.e., both beneficial and detrimental) effects on cellular processes associated with tumor development (proliferation, survival, migration, invasion, and multidrug resistance). At least two distinct cell surface receptors are identified for NGAL. This review (i) summarizes our current knowledge of NGAL’s expression profiles in solid tumors and leukemias, and (ii) critically evaluates the beneficial and detrimental activities of NGAL having been documented in a diverse range of cancer-derived cell lines. A better understanding of the causal relationships between NGAL dysregulation and tumor development will require a fine analysis of the molecular aspects and biological role(s) of NGAL both in primary tumors and at different stages of disease. Having an accurate picture of NGAL’s contribution to tumor progression is a prerequisite for attempting to modulate this protein as a putative therapeutic target.

Neutrophil Gelatinase-Associated Lipocalin as a Biomarker of Allograft Function After Renal Transplantation: Evaluation of the Current Status and Future Insights

Neutrophil gelatinase‐associated lipocalin (NGAL), a protein belonging to the lipocalin superfamily initially found in activated neutrophils, is expressed by several cell types, including kidney tubule. The increase in NGAL production and release from tubular cells in response to various insults has been proven to predict acute kidney injury (AKI). For this reason, it has emerged as a valuable noninvasive biomarker of AKI in clinical nephrology. Also in the renal transplant setting, different studies have indicated NGAL as a valuable tool, especially in the early postoperative period, since the currently available clinical and laboratory parameters remain poorly sensitive to monitor immediate posttransplant graft function. This is an analysis of the recent literature to assess the utility of plasma and urinary NGAL, exosomal mRNA for NGAL, and NGAL levels in the perfusate of machine‐perfused kidneys for the prediction of graft function recovery in the early postsurgery phase after renal transplantation. We found that NGAL appears as a promising troponin‐like biomarker to detect short‐term impairment of graft function after renal transplant, but there are still some limitations in its clinical application, essentially related to its low specificity. Moreover, comparing NGAL assayed in serum, urine, machine‐perfusate, or as exosomal mRNA, each one has shown limitations and benefits in terms of predictive performance for DGF, according to various existing studies, feasibly due to different cut‐off levels, designs and patient sample sizes.

S1P Provokes Tumor Lymphangiogenesis via Macrophage-Derived Mediators Such as IL-1β or Lipocalin-2

A pleiotropic signaling lipid, sphingosine-1-phosphate (S1P), has been implicated in various pathophysiological processes supporting tumor growth and metastasis. However, there are only a few descriptive studies suggesting a role of S1P in tumor lymphangiogenesis, which is critical for tumor growth and dissemination. Corroborating own data, the literature suggests that apoptotic tumor cell-derived S1P alters the phenotype of tumor-associated macrophages (TAMs) to gain protumor functions. However, mechanistically, the role of TAM-induced lymphangiogenesis has only been poorly described, mostly linked to the production of lymphangiogenic factors such as vascular endothelial growth factor C (VEGF-C) and VEGF-D, or transdifferentiation into lymphatic endothelial cells. Recent findings highlight a rather underappreciated role of S1P in tumor lymphangiogenesis, referring to the production of interleukin-1β (IL-1β) and lipocalin-2 (LCN2) by a tumor-promoting macrophage phenotype. In this review, we aim to provide to the readers with the current understanding of the molecular mechanism how apoptotic cell-derived S1P triggers TAMs to promote lymphangiogenesis.

Lipocalin-2 and iron trafficking in the tumor microenvironment

Iron is an essential element for virtually all organisms. It facilitates cell proliferation and growth but also contributes to major hallmarks of cancer such as tumor initiation, growth, and metastasis. Often, iron handling of tumor cells is disturbed, with altered iron acquisition, efflux, and storage. Targeting perturbed iron metabolic pathways might open opportunities towards novel approaches in cancer treatment. It is becoming clear that cells of the tumor microenvironment such as macrophages contribute to tumor progression. Since macrophages evolved a multitude of mechanisms to sequester, transport, store, and release iron it can be speculated that tumor cells educate them to supply iron to support tumor growth. Recent evidence supports the existence of transferrin-independent iron transport mechanisms in the tumor microenvironment, which points to local iron transport proteins such as lipocalin-2 and/or low molecular weight iron-trafficking substances such as siderophores. We hypothesize that tumor cells educate immune cells, i.e. macrophages in their neighborhood to make them delivering iron for the benefit of cancer progression. In particular, we pay attention to recent developments, pointing to lipocalin-2 and siderophores as alternative iron transport molecules in the tumor microenvironment.

Tumour stroma-derived lipocalin-2 promotes breast cancer metastasis

Tumour cell-secreted factors skew infiltrating immune cells towards a tumour-supporting phenotype, expressing pro-tumourigenic mediators. However, the influence of lipocalin-2 (Lcn2) on the metastatic cascade in the tumour micro-environment is still not clearly defined. Here, we explored the role of stroma-derived, especially macrophage-released, Lcn2 in breast cancer progression. Knockdown studies and neutralizing antibody approaches showed that Lcn2 contributes to the early events of metastasis in vitro. The release of Lcn2 from macrophages induced an epithelial-mesenchymal transition programme in MCF-7 breast cancer cells and enhanced local migration as well as invasion into the extracellular matrix, using a three-dimensioanl (3D) spheroid model. Moreover, a global Lcn2 deficiency attenuated breast cancer metastasis in both the MMTV-PyMT breast cancer model and a xenograft model inoculating MCF-7 cells pretreated with supernatants from wild-type and Lcn2-knockdown macrophages. To dissect the role of stroma-derived Lcn2, we employed an orthotopic mammary tumour mouse model. Implantation of wild-type PyMT tumour cells into Lcn2-deficient mice left primary mammary tumour formation unaltered, but specifically reduced tumour cell dissemination into the lung. We conclude that stroma-secreted Lcn2 promotes metastasis in vitro and in vivo, thereby contributing to tumour progression. Our study highlights the tumourigenic potential of stroma-released Lcn2 and suggests Lcn2 as a putative therapeutic target. Copyright © 2016 Pathological Society of Great Britain and Ireland. Published by John Wiley & Sons, Ltd.

Type of Renal Replacement Therapy (Hemodialysis versus Peritoneal Dialysis) Does Not Affect Cytokine Gene Expression or Clinical Parameters of Renal Transplant Candidates

Patients with renal failure suffer from immune disturbances, caused by uremic toxins and influenced by dialysis treatment. The aim of the present study was to reveal whether type of dialysis modality (hemodialysis, HD, versus peritoneal dialysis, PD) differentially affects the immunocompetence, particularly the expression of genes involved in the immune response. Material. 87 renal transplant candidates (66 HD, 21 PD) were included in the study. Methods. The peripheral blood RNA samples were obtained with the PAXgene Blood system just before transplantation. The gene expression of CASP3, FAS, TP53, FOXP3, IFNG, IL2, IL6, IL8, IL10, IL17, IL18, LCN2, TGFB1, and TNF was assessed with real-time PCR on custom-designed low density arrays (TaqMan). Gene expression data were analyzed in relation to pretransplant clinical parameters. Results. The mean expression of examined genes showed no significant differences between PD and HD with the exception of FAS, expression of which was 30% higher in PD patients compared to the HD group. There was nonsignificantly higher expression of proinflammatory cytokines in the PD group. The clinical inflammatory parameters (CRP, albumin, cholesterol, and hemoglobin levels) did not differ between the groups. Conclusion. Type of renal replacement therapy exerts no differential effect on cytokine gene expression or inflammatory clinical parameters.

Clinical significance of neutrophil gelatinase-associated lipocalin in Crimean-Congo hemorrhagic Fever

Neutrophil gelatinase-associated lipocalin (NGAL), which is an important prognostic marker for sepsis and inflammatory diseases, is mostly released from neutrophils. Crimean-Congo hemorrhagic fever (CCHF) patients are generally neutropenic. We aimed to investigate whether there is a change in serum NGAL level and to investigate its effect on the recovery time (RT) during the course of CCHF. A total of 40 CCHF patients (19 females and 21 males) and 34 healthy controls (17 females and 17 males) were included in the study. The serum NGAL level and biochemical and hematological parameters were checked. The NGAL level of CCHF patients was significantly higher than that of the healthy controls (P < 0.001). A multivariate analysis showed that the independent prognostic factor for the prediction of the RT is the NGAL level (odds ratio [OR] 0.3, 95% confidence interval [Cl] 0.1-0.4, P < 0.001). An elevated NGAL level was found to be associated with an increased RT in CCHF patients. The NGAL levels of CHHF patients might be elevated due to increased cytokine release, the presence of a tissue injury, and the release of immature neutrophils from the bone marrow into the peripheral stream. This may be a good prognostic factor in CHHF patients.

Clinical significance of neutrophil gelatinase-associated lipocalin in Crimean-Congo hemorrhagic Fever

Neutrophil gelatinase-associated lipocalin (NGAL), which is an important prognostic marker for sepsis and inflammatory diseases, is mostly released from neutrophils. Crimean-Congo hemorrhagic fever (CCHF) patients are generally neutropenic. We aimed to investigate whether there is a change in serum NGAL level and to investigate its effect on the recovery time (RT) during the course of CCHF. A total of 40 CCHF patients (19 females and 21 males) and 34 healthy controls (17 females and 17 males) were included in the study. The serum NGAL level and biochemical and hematological parameters were checked. The NGAL level of CCHF patients was significantly higher than that of the healthy controls (P < 0.001). A multivariate analysis showed that the independent prognostic factor for the prediction of the RT is the NGAL level (odds ratio [OR] 0.3, 95% confidence interval [Cl] 0.1-0.4, P < 0.001). An elevated NGAL level was found to be associated with an increased RT in CCHF patients. The NGAL levels of CHHF patients might be elevated due to increased cytokine release, the presence of a tissue injury, and the release of immature neutrophils from the bone marrow into the peripheral stream. This may be a good prognostic factor in CHHF patients.

Neutrophil Gelatinase Associated Lipocalin (NGAL) - a biomarker of renal dysfunction in patients with liver cirrhosis: Do we have enough proof?

RATIONALE

Renal dysfunction has a serious impact on the natural evolution of liver cirrhosis. Treatment and prognosis may be improved if an early diagnosis could be established, and specific therapeutic interventions would be applied. Although RIFLE and AKIN classifications have been successfully implemented in the clinical practice of Nephrology and Intensive Care Units, these did not provide major improvements in patients with liver cirrhosis. In the last decade, various biomarkers of kidney injury have been assessed, and Neutrophil Gelatinase-Associated Lipocalin (NGAL) is one of the most promising and most studied novel biomarker.

OBJECTIVE

To offer a brief evaluation on current data on the utility of this biomarker in patients with liver cirrhosis.

METHODS AND RESULTS

We have searched through current literature and analyzed all significant full text articles on this topic.

DISCUSSIONS

NGAL and other new kidney injury molecules may be useful in patients with liver cirrhosis, particularly in identifying structural kidney dysfunction, but larger validation studies to confirm this observation are needed.

Neutrophil gelatinase-associated lipocalin in blood in children with inflammatory bowel disease

BACKGROUND

Neutrophil gelatinase-associated lipocalin (NGAL) is a 25 kDa glycoprotein present in the bodily fluids and tissues. It is secreted by neutrophils, epithelial cells, hepatocytes and adipocytes, and its expression is highly increased in response to cellular stress. The role of NGAL in the pathophysiology of inflammatory bowel disease including Crohn's disease and ulcerative colitis in children has thus far not been studied.

METHODS

The following groups of children were included: (i) inflammatory bowel disease group, n = 36, aged from 1 to 18 years with Crohn's disease (n = 19) and ulcerative colitis (n = 17); (ii) control group, n = 126; and (iii) disease control group, n = 27, without inflammatory bowel disease, with a food and/or inhalant allergy.

RESULTS

Healthy children aged from 1 to 8 years exhibited lower NGAL level than those of 9 to 18 years old (39.0; 18.1-83.7 ng/mL vs 57.6; 28.7-107 ng/mL, P = 0.001). In the younger, but not in the older children, the serum NGAL level correlated with their age, r = 0.334, P = 0.001. In children with inflammatory bowel disease, serum NGAL level was higher (108; 37.3-245 ng/mL) than in healthy (42.0; 18.1-107 ng/mL) and allergic, noninflammatory bowel disease children (49.3; 19.3-107 ng/mL), P = 0.001. Serum NGAL levels in Crohn's disease and ulcerative colitis children did not correlate with age, gender, disease activity, and indices of the inflammation.

CONCLUSION

Serum NAGL levels are highly elevated in Crohn's disease and ulcerative colitis in children compared to the healthy control group. Systematic studies are needed to explain the role of this protein in the inflammatory bowel disease.

Drug-induced nephrotoxicity: clinical impact and preclinical in vitro models

The kidney is a major target for drug-induced toxicity. Drug-induced nephrotoxicity remains a major problem in the clinical setting, where the use of nephrotoxic drugs is often unavoidable. This leads frequently to acute kidney injury, and current problems are discussed. One strategy to avoid such problems would be the development of drugs with decreased nephrotoxic potential. However, the prediction of nephrotoxicity during preclinical drug development is difficult and nephrotoxicity is typically detected only late. Also, the nephrotoxic potential of newly approved drugs is often underestimated. Regulatory approved or validated in vitro models for the prediction of nephrotoxicity are currently not available. Here, we will review current approaches on the development of such models. This includes a discussion of three-dimensional and microfluidic models and recently developed stem cell based approaches. Most in vitro models have been tested with a limited number of compounds and are of unclear predictivity. However, some studies have tested larger numbers of compounds and the predictivity of the respective in vitro model had been determined. The results showed that high predictivity can be obtained by using primary or stem cell derived human renal cells in combination with appropriate end points.