Neutrophil gelatinase-associated lipocalin as the real-time indicator of active kidney damage

Irreversible renal damage after transient renin-angiotensin system stimulation: involvement of an AT1-receptor mediated immune response

Transient activation of the renin-angiotensin system (RAS) induces irreversible renal damage causing sustained elevation in blood pressure (BP) in Cyp1a1-Ren2 transgenic rats. In our current study we hypothesized that activation of the AT₁-receptor (AT₁R) leads to a T-cell response causing irreversible impairment of renal function and hypertension. Cyp1a1-Ren2 rats harbor a construct for activation of the RAS by indole-3-carbinol (I3C). Rats were fed a I3C diet between 4–8 weeks of age to induce hypertension. Next, I3C was withdrawn and rats were followed-up for another 12 weeks. Additional groups received losartan (20 mg/kg/day) or hydralazine (100 mg/kg/day) treatment between 4–8 weeks. Rats were placed for 24h in metabolic cages before determining BP at week 8, 12 and 20. At these ages, subsets of animals were sacrificed and the presence of kidney T-cell subpopulations was investigated by immunohistochemistry and molecular marker analysis. The development of sustained hypertension was completely prevented by losartan, whereas hydralazine only caused a partial decrease in BP. Markers of renal damage: KIM-1 and osteopontin were highly expressed in urine and kidney samples of I3C-treated rats, even until 20 weeks of age. Additionally, renal expression of regulatory-T cells (Tregs) was highly increased in I3C-treated rats, whereas the expression of T-helper 1 (Th1) cells demonstrated a strong decrease. Losartan prevented these effects completely, whereas hydralazine was unable to affect these changes. In young Cyp1a1-Ren2 rats AT₁R activation leads to induction of an immune response, causing a shift from Th1-cells to Tregs, contributing to the development of irreversible renal damage and hypertension.

Prognostic value of NGAL staining in patients with IgA nephropathy

BACKGROUND

Renal tubulointerstitial injury plays an important role in disease progression of IgAN. Neutrophil gelatinase-associated lipocalin (NGAL) is a stress protein released by tubular cells. NGAL is a promising biomarker of acute kidney injury. There is a growing literature suggesting that NGAL is also a marker of chronic kidney disease and severity. Our aim was to evaluate the prognostic value of NGAL staining in patients with IgAN.

METHODS

This retrospective study included all consecutive patients who underwent a renal biopsy at our center between January 2005 and December 2009. Forty-five patients with IgA nephritis were enrolled, and renal biopsy specimens of 29 patients were evaluated. We evaluated baseline age, sex, hypertension, serum creatinine, glomerular filtration rate (GFR), urine protein, NGAL staining, glomerulosclerosis, interstitial fibrosis, and extracapillary proliferation. The primary endpoint of this study was doubling of baseline serum creatinine and/or the onset of ESRD in the course of the study. At the end of the follow-up, patients whose estimated GFR (eGFR) was ≤15 mL/min/1.73 m(2) and/or baseline serum creatinine doubled, were defined as the progressor group.

RESULTS

Nineteen patients (65.5%) were NGAL positive and 10 patients (34.5%) were NGAL negative. Female gender and hypertension were associated with NGAL-positive staining. Urinary protein excretion and serum creatinine levels were more elevated in the NGAL-positive group, but the difference was not significant. We found NGAL-positive staining in major proportion in the progressor group (88.9%) than the non-progressor group (55%) (p = 0.076).

CONCLUSION

NGAL staining can be a new histological marker in IgAN progression.

Neutrophil gelatinase-associated lipocalin as a follow-up marker in critically ill pediatric patients with established acute kidney injury

AIM

To assess the utility of neutrophil gelatinase-associated lipocalin (NGAL) in both urine and serum as a follow-up marker for the discrimination of prerenal acute kidney injury (AKI) from intrinsic AKI in critically ill pediatric patients with established AKI at the time of patient presentation.

PATIENTS AND METHODS

This was a prospective cohort study of a heterogeneous group of critically ill children in the pediatric intensive care unit (PICU). Serum creatinine (SCr) values were obtained daily as part of routine patient care. AKI was defined as a 50% or greater increase in SCr from baseline and classified as prerenal and intrinsic AKI.

RESULTS

A total of 32 critically ill children (mean age: 105 ± 71.7 months, 56% female) with established AKI were included to the study. Area under curve (AUC) for urine and serum NGAL to distinguish prerenal AKI from intrinsic AKI was 0.94, 95% confidence interval (CI): 0.869-1.02 (p < 0.001) and 0.86, 95% CI: 0.71-1.02 (p = 0.002), respectively.

CONCLUSION

In a heterogeneous group of critically ill children with established AKI, we found that NGAL in both urine and serum at the time of patient presentation discriminated intrinsic AKI from prerenal AKI.

Serum NGAL in Critically Ill Children in ICU from a Single Center in Egypt

Introduction. The mortality and morbidity associated with acute kidney injury (AKI), unfortunately, remain unacceptably high. We aimed to detect the extent of serum neutrophil gelatinase-associated lipocalin (NGAL) to early detect AKI in critically ill children. Subjects and Methods. This is a case control study. It included 75 subjects that include 15 as controls and 60 critically ill children. Patients were further subdivided according to RIFLE criteria into two other categories: patients who developed AKI and patients who did not develop AKI. Serum NGAL assayed on admission and after 3 days. Results. There was significant increase in the level of NGAL among patients group when compared with control group. Also, 21.7% of children admitted to PICU developed AKI from which 8.3% needed dialysis. The receiver operating characteristic curve of NGAL at day 0 revealed AUC of 0.63 with 95% CI of 0.50–0.77. At a cutoff value of 89.5 ng/mL, the sensitivity of NGAL was 84.6%, while specifcity was 59.6%, positive predictive value was 36.7%, negative predictive value was 68.4%, and accuracy was 93.3% in diagnosis of AKI. Conclusion. We found that NGAL acts as a sensitive marker rather than a specific one for AKI. At the same time, it presents as a negative predictive value more valuable than being a positive predictive value in detecting AKI.

Creatine pretreatment prevents birth asphyxia-induced injury of the newborn spiny mouse kidney

BACKGROUND

Acute kidney injury (AKI) is a major complication for infants following an asphyxic insult at birth. We aimed to determine if kidney structure and function were affected in an animal model of birth asphyxia and if maternal dietary creatine supplementation could provide an energy reserve to the fetal kidney, maintaining cellular respiration during asphyxia and preventing AKI.

METHODS

Pregnant spiny mice were maintained on normal chow or chow supplemented with creatine from day 20 gestation. On day 38 (term ~39 d), pups were delivered by cesarean section (c-section) or subjected to intrauterine asphyxia. Twenty-four hours after insult, kidneys were collected for histological or molecular analysis. Urine and plasma were also collected for biochemical analysis.

RESULTS

AKI was evident at 24 h after birth asphyxia, with a higher incidence of shrunken glomeruli (P < 0.02), disturbance to tubular arrangement, tubular dilatation, a twofold increase (P < 0.02) in expression of Ngal (early marker of kidney injury), and decreased expression of the podocyte differentiation marker nephrin. Maternal creatine supplementation prevented the glomerular and tubular abnormalities observed in the kidney at 24 h and the increased expression of Ngal.

CONCLUSION

Maternal creatine supplementation may prove useful in ameliorating kidney injury associated with birth asphyxia.

Urine neutrophil gelatinase-associated lipocalin (NGAL) as a biomarker for acute canine kidney injury

Background

Biomarkers for the early prediction of canine acute kidney injury (AKI) are clinically important. Recently, neutrophil gelatinase-associated lipocalin (NGAL) was found to be a sensitive biomarker for the prediction of human AKI at a very early stage and the development of AKI after surgery. However, NGAL has not yet been studied with respect to dog kidney diseases. The application of NGAL canine AKI was investigated in this study.

Results

The canine NGAL gene was successfully cloned and expressed. Polyclonal antibodies against canine NGAL were generated and used to develop an ELISA for measuring NGAL protein in serum and urine samples that were collected from 39 dogs at different time points after surgery.

AKI was defined by the standard method, namely a serum creatinine increase of greater than or equal to 26.5 μmol/L from baseline within 48 h. At 12 h after surgery, compared to the group without AKI (12 dogs), the NGAL level in the urine of seven dogs with AKI was significantly increased (median 178.4 pg/mL vs. 88.0 pg/mL), and this difference was sustained to 72 h.

Conclusion

As the increase in NGAL occurred much earlier than the increase in serum creatinine, urine NGAL seems to be able to serve as a sensitive and specific biomarker for the prediction of AKI in dogs.

Urinary NGAL Ratio Is Not a Sensitive Biomarker for Monitoring Acute Tubular Injury in Kidney Transplant Patients: NGAL and ATI in Renal Transplant Patients

Urinary neutrophil gelatinase-associated lipocalin (uNGAL) is known to predict the prolonged delayed graft function after kidney transplantation. We examined the relation of uNGAL with histological findings of acute tubular injury (ATI). Analyses were made in biopsies taken at 6 weeks, 3 months, and 6 months after kidney transplantation. uNGAL was measured in the spot urines, normalized to urinary creatinine excretion, and correlated to biopsy findings and clinical, laboratory, and demographic variables. Controls included healthy individuals, individuals after kidney donation and ICU patients with acute kidney failure. Renal transplant recipients without ATI did not display elevated uNGAL levels compared to the healthy controls. Transplant patients with ATI had a higher uNGAL excretion at 6 weeks than patients without ATI (27,435 versus 13,605 ng/g; P = 0.031). This increase in uNGAL was minor compared to ICU patients with acute renal failure (2.05 × 106 ng/g). Patients with repeated findings of ATI or severe ATI did not have higher urinary NGAL levels compared to those with only one ATI finding or moderate ATI. Female recipient gender and urinary tract infection were identified as potential confounders. uNGAL has a relation with histological signs of acute tubular injury. The usability of this biomarker in renal allograft recipients is limited because of the low sensitivity.

Generation of human neutrophil gelatinase-associated lipocalin monoclonal antibodies for use in ARCHITECT® assay

Development of a robust immunoassay requires the selection of monoclonal antibodies with desired properties. These properties generally include kinetics parameters such as on-rate and off-rate (i.e., binding affinity), and, often times, the ability to form a sandwich with the analyte of interest. We sought to obtain antibodies suitable for development of an immunoassay capable of detecting human neutrophil gelatinase-associated lipocalin (NGAL), a glycosylated lipocalin of 25 kDa expressed in kidney tubules in response to injury that has been shown to be a urinary biomarker capable of diagnosing acute kidney injury. We immunized CAF1/J and RBF/DnJ mouse strains with recombinant NGAL, and a robust immune response, as measured by serum antibody titer, was observed among all CAF1/J mice. Antibodies secreted from mouse B cell-myeloma hybridomas were screened by enzyme immunoassay (EIA) and by surface plasmon resonance using a method we termed hybrid supernatant kinetic screening. Approximately 300 hybrid clones were evaluated by this technique to identify antibodies with the kinetic binding parameters meeting criteria required for further assay development (i.e., rapid association and slow dissociation). This data, along with epitope grouping, cell growth, cell viability, and antibody secretion, were used to identify antibodies for testing in the ARCHITECT assay.

Relation of systemic and urinary neutrophil gelatinase-associated lipocalin levels to different aspects of impaired renal function in patients with acute decompensated heart failure

Both urine and serum neutrophil gelatinase-associated lipocalin (NGAL) reflect active chronic kidney disease and predict acute kidney injury. However, a direct comparison of these markers in acute decompensated heart failure has not been performed. We prospectively evaluated 93 patients admitted with acute decompensated heart failure and treated with intravenous furosemide and measured both systemic (serum) and urine NGAL levels and their corresponding markers of estimated glomerular filtration rate, natriuresis (urine sodium), and diuretic response (net output, urine sodium/furosemide ratio). In our study cohort, the median urine and serum NGAL level was 34 ng/ml (interquartile range 24 to 86) and 252 ng/ml (interquartile range 175 to 350), respectively. The urine and serum NGAL levels correlated modestly (r = 0.37, p <0.001). Higher urine (but not systemic) NGAL correlated with the markers of impaired natriuresis and reduced diuresis (p <0.005 for all). In contrast, higher serum NGAL demonstrated a stronger relation with reduced glomerular filtration function (p <0.0001). Both markers predicted acute kidney injury (urine NGAL, odds ratio 1.7, p = 0.035; serum NGAL, odds ratio 1.9, p = 0.009). In conclusion, in patients with acute decompensated heart failure, urine NGAL levels reflect renal distal tubular injury with impaired natriuresis and diuresis, and systemic NGAL levels demonstrate a stronger association with glomerular filtration function. Both systemic and urine NGAL predict worsening renal function.

Urinary neutrophil gelatinase-associated lipocalin predicts mortality and identifies acute kidney injury in cirrhosis

BACKGROUND

Kidney failure predicts mortality in patients with cirrhosis. Identification of kidney failure etiology and recognition of those at the highest mortality risk remains a challenge.

AIMS

We hypothesized that urinary neutrophil gelatinase-associated lipocalin (uNGAL) predicts mortality and identifies hepatorenal syndrome (HRS) in patients with cirrhosis.

METHODS

Prospectively enrolled patients with cirrhosis were investigated by uNGAL immunoblot upon hospital admission. Kidney failure type was determined blinded to NGAL measurements.

RESULTS

One hundred eighteen patients were enrolled. Fifty-two (44 %) patients had normal kidney function, 14 (12 %) stable chronic kidney disease, 17 (14 %) prerenal azotemia, 20 (17 %) HRS, and 15 (13 %) intrinsic acute kidney injury (iAKI). Patients with HRS had uNGAL levels intermediate between prerenal azotemia [median (IQR) 105 (27.5-387.5) vs. 20 (15-45) ng/mL, p = 0.004] and iAKI [325 (100-700), p < 0.001]. Fifteen (13 %) patients died. In unadjusted analysis, uNGAL predicted inpatient mortality (OR 2.00, 95 % CI 1.36-2.94) and mortality or liver transplantation (OR 2.01, 95 % CI 1.42-2.85). In multiple regression models, uNGAL > 110 ng/mL (OR 6.05, 95 % CI 1.35-27.2) and HRS (OR 6.71, 95 % CI 1.76-25.5) independently predicted mortality, adjusting for age and serum creatinine >1.5 mg/dL.

CONCLUSIONS

uNGAL strongly predicts short-term inpatient mortality in both unadjusted and adjusted models. Patients with HRS may have uNGAL levels intermediate between those with prerenal azotemia and iAKI. Further studies are needed to determine if uNGAL can improve discrimination of HRS from other types of acute kidney injury and predict short- and long-term cirrhosis outcomes.

Tubular markers are associated with decline in kidney function in proteinuric type 2 diabetic patients

Our aim was to investigate u-NGAL, u-KIM1 and p-FGF23 and prediction of decline in kidney function in type 2 diabetic patients with proteinuria.

METHODS

We performed a follow-up study, follow-up median (range) 3.5 (1-5) years. At baseline u-NGAL, u-KIM1 and p-FGF23 (ELISA) was measured and patients were followed yearly with estimated(e)-GFR (MDRD) and u-albumin.

RESULTS

We included 177 patients (44 women), mean age (SD) 59 (9) years. eGFR 90 (24) ml/min/1.73 m(2) at baseline, u-albumin: median (interquartile range) 104 (39-238) mg/24 h. Patients with levels of u-KIM1 in the highest quartile had a greater decline in eGFR than patients with the lowest quartile 6.0 (5.4) versus 3.2 (5.5) ml/min/1.73 m(2) per year (p=0.02). u-NGAL in the highest versus lowest quartile eGFR decline: 5.1 (4.7) and 2.8 (7.1)ml/min/1.73 m(2) per year (p=0.07). Higher values of u-NGAL and u-KIM1 were associated with enhanced decline in eGFR (R=0.16 and R=0.19, p<0.05), however not after adjustment for progression promoters. p-FGF23 was not predictive of decline in eGFR.

CONCLUSION

Higher levels of markers of tubular damage are associated with a faster decline in eGFR. However, since this is not independent of known progression promoters, measurement of tubular markers does not give additional prognostic information.

Elevated urinary neutrophil gelatinase-associated lipocalcin after acute heart failure treatment is associated with worsening renal function and adverse events

AIMS

Reliable detectors of worsening renal function (WRF) in Emergency Department (ED) patients with acute heart failure (AHF) are limited. We hypothesized that initial urinary neutrophil gelatinase-associated lipocalcin (NGAL) levels, and changes in urinary NGAL levels after initial ED AHF therapy, would be associated with WRF and adverse events.

METHODS AND RESULTS

Urinary NGAL upon ED presentation and 12-24 h after ED treatment was measured in a cohort of ED patients with AHF. NGAL was corrected for urinary creatinine (uCr). WRF was defined as RIFLE stages 1, 2, or 3, or a creatinine increase of ≥0.3 mg/dL. Patients were prospectively followed for 5- and 30-day adverse cardiovascular events. The 399 patients had a median age of 63 years, 50% were Caucasian, and 62% were male. Those with WRF at 72-96 h were more likely to have a higher initial NGAL value (71 vs. 32 ng NGAL/mg uCr) (P = 0.005), and a higher NGAL level at 12-24 h after ED therapy (107 vs. 25ng NGAL/mg uCr, P < 0.001). In a multivariable model, NGAL at 12-24 h remained a significant predictor of WRF (P = 0.012). Of all variables available 12-24 h after initial therapy, the only significant predictor of 30-day events was an elevated urinary NGAL level (P = 0.02).

CONCLUSIONS

Urinary NGAL levels determined 12-24 h after ED therapy are significantly associated with both WRF at 72-96 h and 30-day adverse events. This suggests that early management strategies may have an impact on subsequent WRF and outcomes. If confirmed, NGAL may have a role for guiding therapeutic decisions.

Measuring urinary tubular biomarkers in type 2 diabetes does not add prognostic value beyond established risk factors

Tubulointerstitial disease plays an important role in the pathophysiology of diabetic kidney disease. To determine whether biomarkers of tubular injury could predict renal outcome and mortality in patients with type 2 diabetes, we measured urinary levels of kidney injury molecule-1 (KIM-1) and glycoprotein non-metastatic melanoma B (Gpnmb), both normalized to the urinary creatinine, in 978 individuals from the Edinburgh Type 2 Diabetes Study. At baseline, 238 patients had an estimated glomerular filtration rate (eGFR) below 60 ml/min/1.73 m2 while 147 and 15 patients had microalbuminuria or overt proteinuria, respectively. Both the urine KIM-1 and Gpnmb to creatinine ratios correlated with the urinary albumin to creatinine ratio, the duration of diabetes, and the stringency of glycemic control but not with blood pressure or baseline eGFR. Higher ratios of each marker were associated with a faster decline in kidney function during 4 years of follow-up; however, this was not independent of the urinary albumin to creatinine ratio. Higher KIM-1, but not Gpnmb ratios were associated with an increased risk of mortality, but this association was no longer significant after adjustment for other risk factors, in particular albuminuria. Thus, tubular injury in persons with type 2 diabetes may contribute to the decline in kidney function; however, measuring the urinary concentration of these two tubular biomarkers does not confer additional prognostic information beyond established risk factors.

Lipocalin 2 performs contrasting, location-dependent roles in APCmin tumor initiation and progression

Evidence that lipocalin 2 (LCN2) is oncogenic has grown in recent years and comes from both animal models and expression analysis from a variety of human cancers. In the intestine, LCN2 is overexpressed in colitis patients and its overexpression is a negative prognostic indicator in colorectal cancer. Functionally, LCN2 has a number of different activities that may contribute to its oncogenic potential, including increasing matrix metalloproteinase activity, control of iron availability and stimulating inflammation. In this report, we examined APCmin intestinal tumorigenesis in an LCN2-deficient background. We found that the loss of LCN2 increased tumor multiplicity specifically in the duodenum, suggesting a potential tumor-suppressive activity. Concurrently, however, LCN2 increased the average small intestinal tumor size particularly in the distal small intestine. We found that this increase was correlated to tumor iron(II) content, suggesting that an iron-scavenging role is important for LCN2 oncogenic activity in the intestine.

Biomarkers in acute heart failure--state of the art

The role of biomarkers in the management of patients with acute heart failure (HF) has evolved rapidly in the past several years. Representing a major burden on health systems, acute HF has increased the need for earlier diagnosis, better risk stratification, and cost-effective treatment to reduce rates of hospitalization. Biomarker-guided diagnosis and treatment have become essential, especially in the acute setting to which the majority of the patients with acute HF initially present. Studies clearly demonstrate the complexity of these patients, who commonly have multiple comorbidities necessitating an integrative approach. Several groundbreaking studies conducted in the past decade have demonstrated how biomarkers, individually or in combination, can outperform conventional laboratory tests used in the emergency department as well as in hospitalized patients with acute HF. In this Review, we will provide an update on biomarkers considered state of the art in the diagnosis and management of patients with acute HF.

Neutrophil gelatinase-associated lipocalin (NGAL) and kidney injury molecule 1 (KIM-1) as predictors of incident CKD stage 3: the Atherosclerosis Risk in Communities (ARIC) Study

BACKGROUND

Identifying individuals at risk of chronic kidney disease (CKD) is critical for timely treatment initiation to slow progression of the disease. Neutrophil gelatinase-associated lipocalin (NGAL) and kidney injury molecule 1 (KIM-1) are known biomarkers of acute kidney injury, but it is unknown whether these markers are associated with incident CKD stage 3 in the general population.

STUDY DESIGN

Matched case-control study.

SETTING & PARTICIPANTS

African American and white participants from the Atherosclerosis Risk in Communities (ARIC) Study who at baseline had an estimated glomerular filtration rate (eGFR) ≥60 mL/min/1.73 m(2) and urinary albumin-creatinine ratio ≤30 mg/g. 143 controls were matched for age, sex, and race to 143 cases of incident CKD stage 3 after 8.6 years of follow-up.

PREDICTORS

Quartile of NGAL and KIM-1.

OUTCOMES & MEASUREMENTS

Incident CKD stage 3 (eGFR <60 mL/min/1.73 m(2) at follow-up and a decrease in eGFR from baseline to follow-up ≥25%).

RESULTS

Both NGAL (P = 0.05) and KIM-1 levels (P < 0.001) were correlated positively with baseline urinary albumin-creatinine ratio; neither was associated with baseline eGFR. Participants with NGAL concentrations in the fourth quartile had more than 2-fold higher odds (adjusted OR, 2.11; 95% CI, 0.96-4.64) of incident CKD stage 3 compared with participants in the first quartile after multivariable adjustment (P-trend = 0.03). Adjustment for urinary creatinine and albumin levels resulted in a nonsignificant association (highest quartile adjusted OR, 1.52; 95% CI, 0.64-3.58; P = 0.2). No significant association between KIM-1 level and incident CKD was observed in crude or adjusted models.

LIMITATIONS

The relatively small sample size of the study limits precision and power to detect weak associations.

CONCLUSIONS

Higher NGAL, but not KIM-1, levels were associated with incident CKD stage 3. Adjustment for urinary creatinine and albumin concentration attenuated this association. Additional studies are needed to confirm these findings and assess the utility of urinary NGAL as a marker of CKD risk.

A lipocalin-derived Peptide modulating fibroblasts and extracellular matrix proteins

Lipocalin family members have been implicated in development, regeneration, and pathological processes, but their roles are unclear. Interestingly, these proteins are found abundant in the venom of the Lonomia obliqua caterpillar. Lipocalins are β-barrel proteins, which have three conserved motifs in their amino acid sequence. One of these motifs was shown to be a sequence signature involved in cell modulation. The aim of this study is to investigate the effects of a synthetic peptide comprising the lipocalin sequence motif in fibroblasts. This peptide suppressed caspase 3 activity and upregulated Bcl-2 and Ki-67, but did not interfere with GPCR calcium mobilization. Fibroblast responses also involved increased expression of proinflammatory mediators. Increase of extracellular matrix proteins, such as collagen, fibronectin, and tenascin, was observed. Increase in collagen content was also observed in vivo. Results indicate that modulation effects displayed by lipocalins through this sequence motif involve cell survival, extracellular matrix remodeling, and cytokine signaling. Such effects can be related to the lipocalin roles in disease, development, and tissue repair.

Association between systemic neutrophil gelatinase-associated lipocalin and anemia, relative hypochromia, and inflammation in chronic systolic heart failure

Neutrophil gelatinase-associated lipocalin (NGAL) is upregulated systemically and by renal tubular cells in response to inflammation and ischemia. Recent interests in NGAL have focused on its ability to predict worsening renal function. However, as an iron-regulatory glycoprotein, the relationship between systemic NGAL levels and indices of anemia has not been examined. In 130 patients with chronic systolic heart failure, the authors examined the relationship between plasma NGAL levels and indices of anemia independent of underlying renal function and systemic markers of inflammation and oxidant stress. Plasma NGAL levels were significantly elevated in patients with anemia vs without anemia (121 [interquartile range, 98-197] vs 72 [interquartile range, 57-98] ng/mL, P<.001). Plasma NGAL levels were inversely correlated with indices of anemia including red blood cell count (r=-0.38, P<.0001), hemoglobin (r=-0.41, P<.0001), and red cell distribution width (r=0.25, P=.007), even in patients with relatively preserved renal function (estimated glomerular filtration rate ≥60 mL/min/1.73 m(2) ; n=83, P<.05 for all). Higher plasma NGAL levels were associated with presence of anemia independent of estimated glomerular filtration rate, plasma high-sensitivity C-reactive protein, and myeloperoxidase levels (odds ratio, 2.38; 95% confidence interval, 1.02-6.20; P=.045). Hence, systemic NGAL levels are independently associated with indices of anemia.

Novel insights into the relationship between glomerular pathology and progressive kidney disease

Both glomerular and tubulointerstitial damage are important factors in the pathophysiology and progression of nephropathy. Glomerular injury is associated with tubulointerstitial inflammation, and many studies show that tubulointerstitial changes correlate well with progressive renal functional decline. Strong evidence supports the concept that once established, proteinuric glomerular injury can cause tubular injury. This review briefly summarizes the pathophysiological consequences of glomerular damage that are responsible for tubulointerstitial injury. It further focuses on tubule-derived renal injury biomarkers that may be used to monitor the progression of kidney disease. This monitoring is predicted to become increasingly useful as novel therapeutic interventions preventing progressive renal damage are introduced. In particular, biomarkers of kidney dysfunction, such as urinary podocytes, kidney injury molecule-1, neutrophil gelatinase-associated lipocalin, hematopoietic growth factor-inducible neurokinin 1, or periostin, might be useful in the diagnosis or detection of early nephropathy and risk assessment of kidney disease. However, these biomarkers require further study before they are used in routine screening or in guiding patient therapy.

Evaluation of an extract of North American ginseng (Panax quinquefolius L.) in Candida albicans-infected complement-deficient mice

ETHNOPHARMACOLOGICAL RELEVANCE

Ginseng is a widely consumed aromatic herb that is purported to have health benefits. Several studies report a beneficial impact of ginseng or its derivatives on Candida albicans infection in mice and suggest that its immune-modulatory properties contribute to this effect. However, these studies generally administered ginseng to experimental animals by injection, whereas people typically ingest ginseng. Furthermore, although disseminated candiasis is typically a disease of immune-impaired hosts, previous studies have generally used immune competent host species in the assessments.

MATERIALS AND METHODS

We evaluated the efficacy of an ingested extract of ginseng against Candida albicans infection in DBA/2J mice, which are highly susceptible to Candida albicans infection. A ginseng extract was added to the drinking water for two days before and for the remainder of the study after intravenous inoculation of mice with Candida albicans. Mice were evaluated for morbidity, mortality, Candida albicans titers, and concentrations of inflammatory cytokines and chemokines.

RESULTS

Ingestion of the ginseng extract did not significantly affect overall morbidity or mortality. However, ingestion of the extract was associated with significantly lower renal titers of Candida albicans and with significantly lower concentrations of some inflammatory cytokines in kidney and/or serum.

CONCLUSIONS

Assessment of morbidity, mortality, inflammatory markers, and renal titers after spontaneous ingestion of ginseng by susceptible hosts represents a comprehensive approach to characterizations of therapeutic efficacy against infectious agents. Our findings extend previous reports of the efficacy of ginseng against Candida albicans by demonstrating significant reductions in infectious load and some markers of inflammation in susceptible mice. Our data therefore support further assessment of the immune-modulatory properties of this widely consumed herb and its components.

One dose of cyclosporine A is protective at initiation of folic acid-induced acute kidney injury in mice

BACKGROUND

In most patients, acute kidney injury (AKI) represents the combined effects of ischemic, toxic and inflammatory insults. No effective pharmacologic interventions have been developed to prevent AKI or to improve outcomes to date. Cyclosporine A (CsA) is a calcineurin inhibitor that mediates T-cell receptor signaling, suppresses inflammatory cytokine expression and inhibits leukocyte migration. It is also a potent inhibitor of mitochondrial permeability, protecting cells from death. These properties make it a potentially valuable drug to prevent or treat AKI. It does, however, carry a significant risk of nephrotoxicity, especially with chronic use. By contrast, a single dose of CsA may be protective while limiting the risk of nephrotoxicity.

METHODS

We conducted a controlled animal experiment in male CD-1 mice. Specifically, mice were subjected to folic acid (FA)-induced AKI and then randomly assigned to sham operation or one of three dosage of CsA treatment groups. Results Intraperitoneal injection of FA consistently induced AKI. Serum interleukin (IL)-6 and urinary neutrophil gelatinase-associated lipocalin (NGAL) rose 1 day after FA injection. Compared to sham treatment, one dose (1 and 5 mg/kg body weight) of CsA significantly reduced kidney tubular cell apoptosis, serum creatinine, blood urea, serum IL-6 and urinary NGAL 2 days after FA injection. It was also shown to block the inflammatory mediator tumor necrosis factor (TNF)-like weak inducer of apoptosis (TWEAK) expression, nuclear factor kappa-B (NFκB) activation, inflammatory cell infiltration and interstitial fibrosis 14 days after treatment in a dose-dependent fashion. By contrast, a dose of 10 mg/kg body weight CsA resulted in nephrotoxicity in the setting of FA-induced AKI.

CONCLUSIONS

A single dose of CsA, currently used for organ transplant, significantly protects mice from FA-induced AKI, presumably through inhibition of cell death, inflammatory reaction, interstitial cell infiltration and fibrosis. The protective effects have the potential to open a completely new line of investigation in the prevention and treatment of AKI.

Prognostic utility of plasma neutrophil gelatinase-associated lipocalin in patients with acute heart failure: the NGAL EvaLuation Along with B-type NaTriuretic Peptide in acutely decompensated heart failure (GALLANT) trial

Aims

Neutrophil gelatinase-associated lipocalin (NGAL) is a measure of acute kidney injury. Renal dysfunction portends significant risk after discharge from acute heart failure (AHF). Thus, a sensitive marker of renal injury might also help to risk stratify HF patients.

Methods and results

GALLANT [NGAL EvaLuation Along with B-type NaTriuretic Peptide (BNP) in acutely Decompensated Heart Failure] was a multicentre, prospective study to assess the utility of plasma NGAL, alone and in combination with BNP, as an early risk marker of adverse outcomes. We studied 186 patients (61% male). There were 29 events (AHF readmissions and all-cause mortality) at 30 days (16%). Patients with events had higher levels of NGAL than those without (134 vs. 84 ng/mL, P < 0.001). The area under the receiver operating characteristic curve was higher for NGAL (0.72) than BNP (0.65), serum creatinine (0.57), or estimated glomerular filtration rate (eGFR; 0.55). In multivariable analyses, NGAL predicted events (P= 0.001), BNP approached significance (P= 0.052 and 0.070 without creatinine and GFR, respectively) while neither serum creatinine nor eGFR were significant. The addition of discharge NGAL over BNP alone improved classification by a net 10.3% in those with events and 19.5% in those without events, for a net reclassification improvement of 29.8% (P= 0.010). Subjects with both BNP and NGAL elevated were at significant risk [hazard ratio (HR) = 16.85, P= 0.006], as were subjects with low BNP and high NGAL (HR = 9.95, P= 0.036).

Conclusions

Plasma NGAL is a measure of kidney injury that at the time of discharge is a strong prognostic indicator of 30 days outcomes in patients admitted for AHF.

Clinical trial registration number: NCT 00693745

Circulating lipocalin 2 is associated with body fat distribution at baseline but is not an independent predictor of insulin resistance: the prospective Cyprus Metabolism Study

OBJECTIVE

Lipocalin 2 (LCN2 or NGAL), a protein derived from neutrophils, macrophages, adipocytes, and other cells, has been proposed to be a link between obesity and insulin resistance (IR), but animal and cross-sectional human studies have revealed conflicting results. We studied the association of serum lipocalin 2 with anthropometric, metabolic, and cardiovascular risk markers in young healthy men cross-sectionally and, for the first time, prospectively after 2 years of follow-up, with and without adjustment for potential confounders including serum creatinine.

DESIGN

Two hundred and seventy-two participants were randomly selected from the Cyprus Metabolism Study (1056 men, 18 years), of whom 93 subjects participated in the follow-up study 2 years after baseline assessment. Associations were also explored between total and free leptin levels (to serve as positive controls) and anthropometric metabolic variables.

RESULTS

In the cross-sectional study, lipocalin 2 levels were marginally correlated in the unadjusted model with central fat distribution but not with body weight or total body fat mass. After adjusting for age, smoking, activity, body mass index, fat percentage, waist-to-hip ratio, and serum creatinine, no correlation was found with any cardiovascular risk factor. There was no correlation with the homeostasis model assessment of IR (HOMA-IR) at baseline. In the prospective analyses, baseline levels of lipocalin 2 were not predictive of any variables in unadjusted or adjusted models. As expected, total and free leptin were associated with anthropometric and metabolic variables both cross-sectionally and prospectively.

CONCLUSIONS

We demonstrate that lipocalin 2 is not an independent predictor of metabolic and cardiovascular risk factors in young men cross-sectionally or prospectively.

Urine neutrophil gelatinase-associated lipocalin identifies unilateral and bilateral urinary tract obstruction

BACKGROUND

Urinary tract obstruction (UTO) is a common problem that can lead to permanent loss of kidney function. Unilateral UTO may be difficult to diagnose. Urinary neutrophil gelatinase-associated Lipocalin (uNGAL) may identify unilateral and bilateral UTO.

METHODS

Retrospective case-control study of patients undergoing hospital admission at three sites. UTO was determined by review of medical records and cases were matched to control patients. uNGAL was measured by immunoblot.

RESULTS

Twenty-four unilateral UTO and 15 bilateral UTO cases were identified. Admission serum creatinine (sCr) (milligram per decilitre) was significantly higher in bilateral UTO, 2.0 (1.1-5.3), but not unilateral UTO, 1.1 (0.8-1.5), compared to controls, 0.9 (0.8-1.2). uNGAL (nanogram per millilitre) was significantly higher both in patients with bilateral UTO, 140 (40-450), and unilateral UTO, 50 (20-100), compared to controls, 20 (10-45).

DISCUSSION

uNGAL identifies kidney injury in unilateral and bilateral UTO even in the absence of an elevated sCr.

Biomarkers of kidney injury

CONTEXT

Acute kidney injury (AKI) represents a common serious clinical problem. Up to date mortality due to AKI, especially in intensive care units, has not been changed significantly over the past 50 years. This is partly due to a delay in initiating renal protective and appropriate therapeutic measures since until now there are no reliable early-detecting biomarkers. The gold standard, serum creatinine, displays poor specificity and sensitivity with regard to recognition of the early period of AKI.

OBJECTIVE

Our objective was to review established markers versus novel urine and serum biomarkers of AKI in humans, which have progressed to clinical phase with regard to their diagnostic and prognostic value.

MATERIALS AND METHODS

A review was performed on the basis of literature search of renal failure, acute kidney injury, and biomarkers in Pubmed.

RESULTS

Next to established biomarkers as creatinine and cystatin C, other molecules such as neutrophil gelatinase-associated lipocalin (NGAL), kidney injury molecule-1 (KIM-1), monocyte chemotactic peptide (MCP-1), Netrin-1, and interleukin (IL)-18 are available and represent promising new markers that, however, need to be further evaluated in the clinical setting for suitability.

DISCUSSION

In clinical settings with incipient AKI, not only the development and the implementation of more sensitive biomarkers are required for earlier treatment initiation in order to attenuate the severity of kidney injury, but also equally important remains the substantial improvement and application of refined and prophylactic therapeutic options in these situations.

CONCLUSION

Adequately powered clinical trials testing a row of biomarkers are warranted before they may qualify for full adoption in clinical practice.

Sensitivity and specificity of urinary neutrophil gelatinase-associated lipocalin and kidney injury molecule-1 for the diagnosis of renal cell carcinoma

BACKGROUND/AIMS

Neutrophil gelatinase-associated lipocalin (NGAL) and kidney injury molecule-1 (KIM-1) are urinary biomarkers of diagnostic relevance in a wide variety of acute and chronic kidney diseases. Their diagnostic sensitivity and specificity for kidney cancer are largely unknown and therefore the subject of this investigation.

METHODS

A prospective cohort study was performed to evaluate urine biomarkers for clear-cell and papillary subtypes of renal cancer (67 patients undergoing nephrectomy) and 55 control patients undergoing non-kidney surgery. Urinary KIM-1 and NGAL concentrations were determined by sensitive and specific ELISAs.

RESULTS

In renal cancer patients, median NGAL excretion was 0.52 (1st to 3rd quartiles: 0.28-0.82) ng/mg urinary creatinine (U(Cr)) before nephrectomy compared to 0.15 (0.04-0.31) ng/mg U(Cr) in controls (p < 0.001), and there was a modest decrease of 30% after nephrectomy (p < 0.008). NGAL was not correlated to tumor size (r = 0.19, p = 0.27) or stage. Before nephrectomy, KIM-1 excretion was 0.68 (0.40-1.12) ng/mg U(Cr) compared to 0.03 (0.01-0.06) in controls (p < 0.001). There was a linear correlation between KIM-1 excretion before nephrectomy and tumor size (Spearman's r = 0.66, p < 0.001), tumor stage, and a 50% decrease in median KIM-1 concentration 1 month following tumor excision (p < 0.01). Biomarker concentration ranges for renal cancer patients and controls overlapped substantially for NGAL but not KIM-1.

CONCLUSION

NGAL is not a sensitive or specific urinary biomarker of kidney cancer. Although KIM-1 had diagnostic sensitivity for kidney cancer, it is well known to reflect many types of kidney injuries, thus limiting its specificity as a diagnostic biomarker for renal cancer.

Levels of neutrophil gelatinase-associated lipocalin in 2 patients with crush syndrome after a mudslide

Neutrophil gelatinase-associated lipocalin is one of the most promising biomarkers for the diagnosis of acute kidney injury. An increase in the level of neutrophil gelatinase-associated lipocalin is a good predictor of acute kidney injury and is associated with an increase in the serum level of creatinine. Two victims of a mudslide in Messina, Italy, initially had crush syndrome followed by development of acute kidney injury. The development of acute kidney injury is the second most common cause of death after large earthquakes and other natural disasters, but at the same time, crush-related acute kidney injury is one of the few life-threatening complications of crush injuries that can be reversed if diagnosed early and treated. In this case, measuring the level of neutrophil gelatinase-associated lipocalin enabled early diagnosis of acute kidney injury and anticipation of the changes in levels of conventional markers such as creatinine.

Early detection and intervention using neutrophil gelatinase-associated lipocalin (NGAL) may improve renal outcome of acute contrast media induced nephropathy: a randomized controlled trial in patients undergoing intra-arterial angiography (ANTI-CIN Study)

BACKGROUND

Patients with pre-existing impaired renal function are prone to develop acute contrast media induced nephropathy (CIN). Neutrophil gelatinase-associated lipocalin (NGAL), a new biomarker predictive for acute kidney injury (AKI), has been shown to be useful for earlier diagnosis of CIN; however, urinary NGAL values may be markedly increased in chronic renal failure at baseline. Results from those studies suggested that urinary NGAL values may not be helpful for the clinician. An intravenous volume load is a widely accepted prophylactic measure and possibly a reasonable intervention to prevent deterioration of renal function. The aim of our study is to evaluate NGAL as an early predictor of CIN and to investigate the clinical benefit of early post-procedural i.v. hydration.

METHODS/DESIGN

The study will follow a prospective, open-label, randomized controlled design. Patients requiring intra-arterial contrast media (CM) application will be included and receive standardized, weight-based, intravenous hydration before investigation. Subjects with markedly increased urinary NGAL values after CM application will be randomized into one of two study groups. Group A will receive 3-4 ml/kg BW/h 0.9% saline intravenously for 6 hours. Group B will undergo only standard treatment consisting of unrestricted oral fluid intake. The primary outcome measure will be CIN defined by an increase greater than 25% of baseline serum creatinine. Secondary outcomes will include urinary NGAL values, cystatin C values, contrast media associated changes in cardiac parameters such as NT-pro-BNP/troponin T, changes in urinary cytology, need for renal replacement treatment, length of stay in hospital and death.We assume that 20% of the included patients will show a definite rise in urinary NGAL. Prospective statistical power calculations indicate that the study will have 80% statistical power to detect a clinically significant decrease of CIN of 40% in the treatment arm if 1200 patients are recruited into the study.

DISCUSSION

A volume expansion strategy showing a benefit from earlier intervention for patients with markedly elevated urinary NGAL values, indicating a CIN, might arise from data from this study.

TRIAL REGISTRATION

ClinicalTrials.gov NCT01292317.

Plasma neutrophil gelatinase-associated lipocalin predicts recovery from acute kidney injury following community-acquired pneumonia

Although plasma neutrophil gelatinase-associated lipocalin (NGAL) is a promising biomarker for early detection of acute kidney injury, its ability to predict recovery is unknown. Using RIFLE criteria to define kidney injury, we tested whether higher plasma NGAL concentrations on the first day of RIFLE-F would predict failure to recover in a post hoc analysis of a multicenter, prospective, cohort study of patients with community-acquired pneumonia. Recovery was defined as alive and not requiring renal replacement therapy during hospitalization or having a persistent RIFLE-F classification at hospital discharge. Median plasma NGAL concentrations were significantly lower among the 93 of 181 patients who recovered. Plasma NGAL alone predicted failure to recover with an area under the receiver operating characteristic curve of 0.74. A clinical model using age, serum creatinine, pneumonia severity, and nonrenal organ failure predicted failure to recover with area under the curve of 0.78. Combining this clinical model with plasma NGAL concentrations did not improve prediction. The reclassification of risk of renal recovery, however, significantly improved by 17% when plasma NGAL was combined with the clinical model. Thus, in this cohort of patients with pneumonia-induced severe acute kidney injury, plasma NGAL appears to be a useful biomarker for predicting renal recovery.

Urinary NGAL is a useful clinical biomarker of HIV-associated nephropathy

BACKGROUND

Urinary neutrophil gelatinase-associated lipocalin (uNGAL) is expressed by kidney tubules that are acutely damaged, but few studies have investigated the association of neutrophil gelatinase-associated lipocalin (NGAL) with different forms of chronic kidney disease (CKD). HIV-associated nephropathy (HIVAN) is a progressive form of CKD characterized by collapsing focal segmental glomerulosclerosis and microcytic tubular dilatation that typically leads to end-stage renal disease (ESRD).

METHODS

Previously, we reported that microcystic tubular dilatations specifically expressed NGAL RNA, implying that the detection of uNGAL protein could mark advanced HIVAN. To test this idea, we performed a comparative study of diverse proteinuric glomerulopathies in 25 patients who were HIV positive.

RESULTS

Eighteen patients had HIVAN and seven had other glomerulopathies (four membranoproliferative glomerulonephritis, one membranous glomerulonephritis, one amyloid and one malarial GN). HIVAN and non-HIVAN patients did not differ with respect to age, ethnicity, serum creatinine, estimated GFR, proteinuria or the prevalence of hypocomplementemia (6 versus 29%, P = 0.18), but HIVAN patients were less likely to have HCV infections. HIVAN patients expressed 4-fold higher levels of uNGAL than the patients with other glomerulopathies [387 ± 338 versus 94 ± 101 μg/g urine creatinine (uCr), P = 0.02]. A cutpoint of 121.5 μg uNGAL/g uCr demonstrated 94% sensitivity and 71% specificity for the diagnosis of HIVAN, with an area under the receiver operator characteristic curve of 0.88.

CONCLUSION

In summary, while HIVAN disease is currently diagnosed only by kidney biopsy, uNGAL can distinguish HIVAN from other proteinuric glomerulopathies in the HIV-infected patient, likely because of its specific expression from characteristic microcysts.

Renal dysfunction is a stronger determinant of systemic neutrophil gelatinase-associated lipocalin levels than myocardial dysfunction in systolic heart failure

BACKGROUND

Neutrophil gelatinase-associated lipocalin (NGAL) is released by renal tubular cells in response to inflammation and injury. Recent studies have demonstrated that NGAL is up-regulated in cardiomyocytes within the failing myocardium. However, the overall relationship between systemic NGAL levels and myocardial structure and performance has not been established.

METHODS AND RESULTS

We measured systemic NGAL levels in 130 subjects with chronic systolic heart failure (HF) and comprehensive echocardiographic evaluation, as well as 69 subjects with acute decompensated systolic HF and hemodynamic evaluation. In the chronic HF cohort, higher plasma NGAL levels were modestly associated with increasing age (r = 0.18; P = .035), higher New York Heart Association functional class (rank sums: P = .022) and impaired renal function (eGFR: r = -0.53; P < .0001; cystatin C: r = 0.60; P < .0001). Plasma NGAL levels were modestly associated with indices of diastolic dysfunction (mitral E/Ea: r = 0.27; P = .002; LAVi: r = 0.25; P = .011; tricuspid E/Ea: r = 0.20; P = .029), but not after adjustment for renal function (P > .10 for all). In Cox proportional hazards analysis, plasma NGAL predicted cardiac death or transplantation after adjustment for age, gender, left ventricular ejection fraction, and mitral E/Ea (hazard ratio 1.68, 95% confidence interval 1.08-2.57; P = .022), but not after adjustment for renal function (P = .83). In the acute HF cohort, we did not observe any relationship between NGAL and hemodynamic indices, but NGAL strongly correlated with renal function.

CONCLUSIONS

Systemic NGAL levels are largely determined by underlying impairment of renal rather than myocardial function. Our findings did not support any prognostic significance or relationship between systemic NGAL levels and indices of cardiac structure and function after adjustment for underlying renal function.

Neutrophil gelatinase-associated lipocalin in the diagnosis of type 1 cardio-renal syndrome in the general ward

BACKGROUND AND OBJECTIVES

The early identification of acute heart failure (HF) patients with type 1 cardio-renal syndrome should be the first step for developing prevention and treatment strategies for these patients. This study aimed to assess the performance of neutrophil gelatinase-associated lipocalin (NGAL) and cystatin C in the early detection of type 1 cardio-renal syndrome in patients with acute HF.

DESIGN, SETTING, PARTICIPANTS, & MEASUREMENTS

One-hundred nineteen patients admitted with acute HF were studied. NGAL and creatinine were measured in the first hospitalization morning; creatinine was also measured at least after 48 to 72 hours. Physicians were blinded to NGAL and cystatin C levels. Type 1 cardio-renal syndrome was defined as an increase in the creatinine level of at least 0.3 mg/dl or 50% of basal creatinine.

RESULTS

Type 1 cardio-renal syndrome developed within 48 to 72 hours in 14 patients (11.8%). Admission NGAL levels were higher in these patients: 212 versus 83 ng/dl. At a cutoff value of 170 ng/L, NGAL determined type 1 cardio-renal syndrome with a sensitivity of 100% and a specificity of 86.7%. The area under the receiver-operating characteristic curve of NGAL was 0.93 and that of cystatin C was 0.68.

CONCLUSIONS

Above a cutoff value of 170 ng/L, NGAL predicts 48- to 72-hour development of type 1 cardio-renal syndrome with a negative predictive value of 100% and a positive predictive value of 50%. NGAL independently associates with type 1 cardio-renal syndrome and might be a useful biomarker in the early recognition of these patients.

Small interfering RNA targeting IKKβ prevents renal ischemia-reperfusion injury in rats

The transcription factor NF-κB has been found critical to the pathogenesis of renal ischemia-reperfusion injury, which is a major cause of acute kidney injury (AKI). Activation of NF-κB is dependent upon the activation of the specific inhibitory κB kinase (IKK) subunit IKKβ. Here, we investigate whether small interfering RNA (siRNA) targeting IKKβ protects rats from renal ischemia- reperfusion injury in vivo. Renal ischemia-reperfusion injury was induced by clamping the renal artery for 45 min. Rats were treated before ischemia with IKKβ siRNA or scrambled siRNA, administered by renal artery injection. Treated animals were evaluated for renal IKKβ protein and mRNA expression, blood biochemistry, tissue histopathology, NF-κB/DNA binding activity, and expression of two downstream inflammatory cytokines, neutrophil gelatinase-associated lipocalin (NGAL) and IL-18. A local injection of IKKβ siRNA resulted in inhibition of renal IKKβ gene expression, NF-κB/DNA binding activity, and expression of NGAL and IL-18. Rats pretreated with IKKβ siRNA had significantly less blood urea nitrogen and serum creatinine levels and less renal tubular damage scores. Consequently, our data confirm that targeted silencing of IKKβ using siRNA substantially diminishes kidney injury and inflammation following ischemia-reperfusion.

Review: Serum and urine biomarkers of kidney disease: A pathophysiological perspective

The use of reliable biomarkers is becoming increasingly important for the improved management of patients with acute and chronic kidney diseases. Recent developments have identified a number of novel biomarkers in serum or urine that can determine the potential risk of kidney damage, distinguish different types of renal injury, predict the progression of disease and have the potential to assess the efficacy of therapeutic intervention. Some of these biomarkers can be used independently while others are more beneficial when used in combination with knowledge of other clinical risk factors. Advances in gene expression analysis, chromatography, mass spectrometry and the development of sensitive enzyme-linked immunosorbent assays have facilitated accurate quantification of many biomarkers. This review primarily focuses on describing new and established biomarkers, which identify and measure the various pathophysiological processes that promote kidney disease. It provides an overview of some of the different classes of renal biomarkers that can be assessed in serum/plasma and urine, including markers of renal function, oxidative stress, structural and cellular injury, immune responses and fibrosis. However, it does not explore the current status of these biomarkers in terms of their clinical validation.

Tubular markers do not predict the decline in glomerular filtration rate in type 1 diabetic patients with overt nephropathy

Recent studies have shown that both glomerular and tubulointerstitial damage are important factors in the pathophysiology and progression of diabetic nephropathy. To examine whether markers of tubular damage are useful in monitoring the progression of disease, we measured urinary levels of neutrophil gelatinase-associated lipocalin (NGAL), liver-fatty acid-binding protein (LFABP), and kidney injury molecule-1 (KIM-1) in a 3-year intervention study of 63 type 1 diabetic patients with kidney disease. The baseline mean glomerular filtration rate (GFR) was 87 ml/min per 1.73 m(2) and urinary albumin excretion 1141 mg/24 h. Patients with the highest compared with the lowest quartile of urinary NGAL at baseline had higher urinary KIM-1 levels and a significant decrease in their GFR each year. Using linear regression analysis, we found that elevated urinary NGAL and KIM-1 concentrations were associated with a faster decline in GFR, but not after adjustment for known promoters of progression. Urinary LFABP was not related to decline in GFR. Losartan treatment (100 mg/day) reduced urinary KIM-1 by 43% over a 12-month period. Thus, urine biomarker measurements in patients with type 1 diabetic nephropathy did not provide additional prognostic information to that of known progression promoters.

Urinary neutrophil gelatinase-associated lipocalin as a marker of acute kidney injury after orthotopic liver transplantation

BACKGROUND

Urinary neutrophil gelatinase-associated lipocalin (NGAL) is a novel, sensitive and specific biomarker that is rapidly released after kidney injury. It predicts acute kidney injury (AKI) in multiple clinical scenarios. We hypothesized that urinary NGAL can predict AKI after liver transplantation.

METHODS

Urine was collected in 92 patients undergoing liver transplantation (18 living-related and 74 deceased) before surgery, after reperfusion of the liver graft and then 3, 18 and 24 h later. NGAL was analyzed with enzyme-linked immunosorbent assay and corrected for dilution/concentration by calculating urinary NGAL/urine creatinine ratios. AKI was defined by Risk-Injury-Failure-Loss-Endstage stage kidney disease (RIFLE)-risk criteria (increase of serum creatinine by >50%).

RESULTS

Urinary NGAL/urine creatinine ratio was low prior to surgery and increased immediately after reperfusion, peaked 3 h later and remained elevated at 18 and 24 h. Urinary NGAL/urine creatinine ratios were higher in patients with post-operative (post-OP) AKI defined by RIFLE--risk criteria 3 and 18 h after reperfusion. The area under the curve of the receiver operator characteristics curve of urinary NGAL/urine creatinine ratio to predict AKI was 0.800 (95% CI: 0.732-0.869, P < 0.0001) 3 h and 0.636 (95% CI: 0.551-0.720, P < 0.005) 18 h after reperfusion.

CONCLUSIONS

We conclude that urinary NGAL/urine creatinine ratio is able to predict post-OP AKI 3 and 18 h after transplantation with good discrimination.