Urinary Excretion Of Neutrophil Gelatinase-associated Lipocalin Research Articles

Effect of 0.9% NaCl compared to plasma-lyte on biomarkers of kidney injury, sodium excretion and tubular transport proteins in patients undergoing primary uncemented hip replacement \u2013 a randomized trial

BackgroundIsotonic saline (IS) is widely used to secure perioperative cardiovascular stability. However, the high amount of chloride in IS can induce hyperchloremic acidosis. Therefore, IS is suspected to increase the risk of acute kidney injury (AKI). Biomarkers may have potential as indicators.MethodsIn a double-blinded, placebo-controlled study, 38 patients undergoing primary uncemented hip replacement were randomized to IS or PlasmaLyte (PL). Infusion was given during surgery as 15 ml/kg the first hour and 5 ml/kg the following two hours. Urinary samples were collected upon admission and the day after surgery. As surgery was initiated, urine was collected over the course of 4 h. Hereafter, another urine collection proceeded until the morning. Urine was analyzed for markers of AKI neutrophil gelatinase-associated lipocalin (NGAL) and kidney injury molecule-1 (KIM-1). Arterious and venous blood samples for measurements of pH and plasma electrolytes including chloride (p-Cl) were collected as surgery was initiated, at the end of surgery and the following morning.ResultsIS induced an increase in p-Cl (111 ± 2 mmol/L after IS and 108 ± 3 after PL, p = 0.004) and a decrease in pH (7.39 ± 0.02 after IS and 7.43 ± 0.03 after PL, p = 0.001). Urinary NGAL excretion increased in both groups (ΔNGAL: 5.5 [4.1; 11.7] μg/mmol creatinine p = 0.004 after IS vs. 5.5 [2.1;9.4] μg/mmol creatinine after PL, p < 0.001). No difference was found between the groups (p = 0.839). Similarly, urinary KIM-1 excretion increased in both groups (ΔKIM-1: IS 115.8 [74.1; 156.2] ng/mmol creatinine, p < 0.001 vs. PL 152.4 [120.1; 307.9] ng/mmol creatinine, p < 0.001). No difference between the groups (p = 0.064).FENa increased (1.08 ± 0.52% after IS and 1.66 ± 1.15% after PL, p = 0.032). ENaC excretion was different within groups (p = 0.019).ConclusionA significantly higher plasma chloride and a lower pH was present in the group receiving isotonic saline. However, u-NGAL and u-KIM-1 increased significantly in both groups after surgery despite absence of changes in creatinine. These results indicate that surgery induced subclinical kidney injury. Also, the IS group had a delayed sodium excretion as compared to the PL group which may indicate that IS affects renal sodium excretion differently from PL.Trial registrationClinicalTrials.gov Identifier: NCT02528448, 19/08/2015

The Influence of Salt Loading on the Kidney Injury Biomarker Neutrophil Gelatinase‐Associated Lipocalin in Healthy Young Adults

PurposeThe kidneys play a critical role in blood pressure (BP) regulation. In hypertensive patients and in rodent models, long‐term high dietary sodium (Na+) causes a reduction in kidney function (reduced glomerular filtration rate; GFR). Rodent studies demonstrate that high dietary Na+ increases levels of novel kidney injury biomarkers, independent of changes in BP and GFR. However, it is unclear if short‐term high Na+ increases kidney injury biomarkers in healthy humans. Therefore, we tested the hypothesis that short‐term high Na+ intake increases urinary excretion of the novel kidney injury marker Neutrophil Gelatinase‐Associated Lipocalin (NGAL) in healthy, young adults.MethodsTwenty participants (12 M/8 F; age: 24±4 years; BMI: 23.1±0.6 kg/m2; BP: 112 ±10/64 ±9 mmHg, mean ± SD) participated in a double‐blind, placebo‐controlled, randomized, crossover study. For 10‐days, participants were asked to consume a 2,300 mg/day Na+ diet and supplement with salt (3,900 mg/day of Na+) or placebo (dextrose) capsules. The conditions were separated by at least two weeks and female participants were tested during the placebo phase of their oral contraceptive cycle. Participants collected their urine for the final 24 hours of each supplementation period to assess urine flow rate, and Na+ excretion to verify diet adherence. Brachial BP was measured after at least five minutes of rest. We measured urine and serum creatinine (kinetic modification via the Jaffe reaction) to estimate GFR via creatinine clearance. We used enzyme‐linked immunosorbent assays (Toronto Bioscience) to measure urinary NGAL. Statistical analysis included paired t‐tests and Wilcoxon matched‐pairs signed rank tests.ResultsCompared to placebo, Na+ supplementation increased urinary Na+ excretion (139.9±68.4 vs. 282.5±69.8 mmol/24 hours, p&lt;0.01) but there was no difference in mean arterial BP (77±7 vs. 77±6 mmHg, p=0.64). Serum creatinine concentrations (0.78±0.12 vs. 0.77±0.09 mg/dL, p=0.55) were not different between conditions. However, compared to placebo, Na+ supplementation increased creatinine clearance (110.5±32.9 vs. 145.0±24.9 mL/min, p&lt;0.01) and increased urinary NGAL excretion indexed to urine flow rate (16.9±21.9 vs. 28.4±36.1 ng/min, p=0.02).DiscussionOur preliminary data suggests that salt loading does not alter serum creatinine concentration but increases creatinine clearance and urinary excretion of the kidney injury marker NGAL in healthy young adults.Support or Funding InformationFundingSupported by NIH grants R01HL128388 and K01HL147998, and ACSM Foundation Doctoral Student Research Grant 17‐00521

Assessment of renal function in obese and overweight children with NGAL and KIM-1 biomarkers.

Aim and background: the incidence of obesity has increased among children, and obesity has been considered an independent risk factor for chronic kidney disease. We aimed to determine the degree of kidney function impairment by evaluating urine neutrophil gelatinase-associated lipocalin (NGAL) and kidney injury molecule-1 (KIM-1) levels. Materials and methods: in total, 15 obese, 26 overweight, and 26 control adolescents aged 10 to 16 years were enrolled into the study. Urine samples were evaluated for NGAL and KIM-1 levels using enzyme-linked immunosorbent assay kits. We investigated the association between obesity and related comorbidities with urinary NGAL and KIM-1 excretion. Results: no significant differences were noted between the obese, overweight, and control groups in urinary NGAL and KIM-1 excretion (p = 0.327 and p = 0.917, respectively). In the obese and overweight groups urinary NGAL levels were 50.39 [30.88-74.22] in females and 26.67 [23.24-45.59] in males (p = 0.013). Also, urinary NGAL levels were increased in obese and overweight adolescents with LDL dyslipidemia at 64.12 [30.98-114.32] as compared to those without LDL dyslipidemia: 39.51 [25.59.56.37] (p = 0.024). Furthermore, a correlation was observed between insulin and homeostasis model assessment of insulin resistance levels with the NGAL/creatinine ratio in the overweight group (r = 0.515; p = 0.008, and r = 0.483; p = 0.014, respectively). Such correlation was not found in the obese group. Conclusion: the effect of obesity on renal function could not be determined in children. A longer exposure may be required for obesity-induced disruption of renal function in children. Renal function may be disrupted by dyslipidemia in obese adolescents. Furthermore, obesity impaired renal function in female adolescents. The normalization of these urinary markers as related to urine creatinine should be discussed.

Urinary Neutrophil Gelatinase-Associated Lipocalin (NGAL) as a Marker of Diabetic Nephropathy in Type 1 Diabetic Patients.

Glomerular and tubulointerstitial damage plays a role in renal function failure in diabetic patients. While both serum and urine levels of neutrophil gelatinase-associated lipocalin (NGAL) show significantly increased levels in acute renal pathologies, the NGAL increase in active phase indicates a reversible condition in chronic cases. 52 type 1 diabetic patients and 30 healthy volunteers participated in the study. The diabetic participants were separated into two groups as follows: a normoalbuminuria group consisting of those with an albumin/creatinine ratio less than 30 mg/g and an albuminuria group consisting of those with an albumin/ creatinine ratio equal or greater than 30 mg/g. Albumin, creatinine and NGAL were measured in all participants. Urinary NGAL median level was 21.1 ng/mL for diabetic patients and 11.9 ng/mL for healthy controls, and the difference between the two groups was statistically significant. When diabetic patients were compared as those with and without albuminuria, the median urinary NGAL levels of normoalbuminuria and albuminuria were 24.7 and 16.1 ng/mL, respectively, but the difference was not statistically significant. Statistically similar results were obtained through evaluation of the ratio of urinary NGAL excretion to creatinine excretion. The NGAL/Cr ratio was significantly higher in diabetic patients than in healthy controls, but no statistically significant difference was found between the diabetic patients with and without albuminuria. Urinary NGAL excretion in type 1 diabetic patients is found to be increased over a wide range, but it does not correlate with urinary albumin excretion. In this regard, urinary NGAL excretion should not be used as an alternative to microalbuminuria in detecting diabetic nephropathy. The greater amount of NGAL excretion among diabetic patients may be due to diabetic nephropathy with possible tubulointerstitial damage pathologies.

Influence of renal ischaemia‐reperfusion injury on renal neutrophil gelatinase‐associated lipocalin receptor (24p3R) in rats

The neutrophil gelatinase-associated lipocalin (NGAL) receptor (24p3R) is expressed in distal nephron and contributes to the endocytosis of NGAL in urine. This study was undertaken to evaluate an influence of renal ischaemia-reperfusion injury on 24p3R. Unilateral renal pedicle was clamped for 0, 10, 20, 30, or 45minutes in male Wistar rats. Urine was collected for 24hours after reperfusion, and ischaemic kidney and blood sample were obtained. Apparent histological injury in the ischaemic kidney was detected in the 30 and 45minutes-treated groups. Urinary NGAL excretion elevated in rats with renal ischaemia for more than 20minutes, while serum creatinine increased in rats for more than 30minutes of ischaemia. Renal protein expression of NGAL did not significantly change. Renal mRNA expressions of megalin and cubilin, which are expressed at renal proximal tubules and uptake NGAL, decreased in animals with renal ischaemia for more than 20minutes. Renal protein expression of 24p3R, which is expressed at renal distal tubules and uptake NGAL, decreased in rats with renal ischaemia for 45min. This study showed for the first time that renal 24p3R decreased in response to renal ischaemia. As relatively longer renal ischaemia (45minutes) decreased renal 24p3R protein and increased urinary NGAL excretion, the down-regulation of 24p3R protein might contribute to the elevated urinary excretion of NGAL in rats with unilateral ischaemia-reperfusion injury.

Protective Role of Apelin Against Cyclosporine-Induced Renal Tubular Injury in Rats

BackgroundCyclosporine (CsA) usually reduces glomerular filtration rate (GFR) but also can induce tubular injury without resulting in GFR reduction. Apelin is an endogenous ligand for the apelin receptor and has diverse physiologic roles related to hemodynamic or metabolic processes. We investigated the renoprotective role of apelin against CsA-induced tubular toxicity in rats. MethodsRats were given CsA (15 mg/kg/day) and/or apelin-13 (15 μg/kg/day) for 7 days via subcutaneous injection. We performed serum and urinary assays of creatinine and neutrophil gelatinase-associated lipocalin (NGAL) to estimate renal injury and performed Western blotting for endothelial nitric oxide synthase and nuclear factor of activated T-cell cytoplasmic 1 (NFATc1) to document the underlying mechanism. ResultsThe CsA-treated group showed increased urinary creatinine excretion, polyuria, and renal glycosuria without GFR reduction, suggesting adequate CsA-induced renal tubular injury. Urinary NGAL excretion also increased significantly in the CsA group. Conversely, apelin attenuated CsA-induced tubular injury and had no effect on urinary NGAL excretion. In histopathologic examination, the apelin-treated group had lower tubulo-interstitial injury scores compared with those in the CsA group. Regarding the effects of apelin, our results indicate that apelin provides protection against CsA-induced tubular injury by activating nitric oxide and/or the NFATc1 pathway. Notably, we also found that CsA inhibits renal glucose reabsorption by reducing Na+-K+ ATPase expression and that apelin reverses reduced renal glucose reabsorption by CsA in tubular cells. ConclusionsOur study demonstrates the renoprotective effect of apelin against CsA-induced renal tubular toxicity and provides novel insights into the effects of CsA and apelin on renal tubular cells.

Identification of a sensitive urinary biomarker, selenium-binding protein 1, for early detection of acute kidney injury

ABSTRACTAcute kidney injury (AKI) is associated with increased mortality rate in patients but clinically available biomarkers for disease detection are currently not available. Recently, a new biomarker, selenium-binding protein 1 (SBP1), was identified for detection of nephrotoxicity using proteomic analysis. The aim of this study was to assess the sensitivity of urinary SBP1 levels as an early detection of AKI using animal models such as cisplatin or ischemia/reperfusion (I/R). Sprague–Dawley rats were injected with cisplatin (6 mg/kg, once i.p.) and sacrificed at 1, 3, or 5 days after treatment. Ischemia was achieved by bilaterally occluding both kidneys with a microvascular clamp for 45 min and verified visually by a change in tissue color. After post-reperfusion, urine samples were collected at 9, 24, and 48 hr intervals. Urinary excretion of protein-based biomarkers was measured by Western blot analysis. In cisplatin-treated rats, mild histopathologic alterations were noted at day 1 which became severe at day 3. Blood urea nitrogen (BUN) and serum creatinine (SCr) levels were significantly increased at day 3. Levels of urinary excretion of SBP1, neutrophil gelatinase-associated lipocalin (NGAL), and a tissue inhibitor of metalloproteinase-1 (TIMP-1) were markedly elevated at day 3 and 5 following drug treatment. In the vehicle-treated I/R group, serum levels of BUN and SCr and AST activity were significantly increased compared to sham. Urinary excretion of SBP1 and NGAL rose markedly following I/R. The urinary levels of SBP1, NGAL, TIMP-1, and KIM-1 proteins excreted by AKI patients and normal subjects were compared. Among these proteins, a marked rise in SBP1 was observed in urine of patients with AKI compared to normal subjects. Based upon receiver-operator curves (ROC), SBP1 displayed a higher area under the curve (AUC) scores than levels of SCr, BUN, total protein, and glucose. In particular, SBP1 protein was readily detected in small amounts of urine without purification. Data thus indicate that urinary excretion of SBP1 may be useful as a reliable biomarker for early diagnosis of AKI in patients.

Testing Danegaptide Effects on Kidney Function after Ischemia/Reperfusion Injury in a New Porcine Two Week Model.

IntroductionIschemia/reperfusion injury (I/R-I) is a leading cause of acute kidney injury (AKI) and is associated with increased mortality. Danegaptide is a selective modifier of the gap junction protein connexion 43. It has cytoprotective as well as anti-arrhythmic properties and has been shown to reduce the size of myocardial infarct in pigs. The aim of this study was to investigate the ischemia-protective effect of Danegaptide in a porcine renal I/R-I model with two weeks follow up.MethodsUnilateral renal I/R-I was induced in pigs by clamping the left renal artery over a two hour period. The model allowed examination of renal blood flow by magnetic resonance imaging (MRI) and the measurement of single kidney GFR two weeks after injury. Eleven animals were randomized to Danegaptide-infusion while nine animals received placebo. Kidney histology and urinary neutrophil gelatinase-associated lipocalin (NGAL) excretion were included as markers of AKI.ResultsUnilateral kidney I/R-I resulted in an immediate ~50% GFR reduction, associated with a four-fold increase in urinary NGAL-excretion. Fourteen days after I/R-I, the total GFR was ~75% of baseline with a significantly lower GFR in the injured left kidney compared to the right kidney. No differences in GFR were observed between the treated and non-treated animals immediately after I/R-I or at Day 14. Furthermore, no differences were observed in the urinary excretion of NGAL, renal blood flow or other markers of renal function.ConclusionsAs expected this porcine renal I/R-I model was associated with reduced GFR two weeks after injury. Danegaptide did not improve renal function after I/R-I.

Growth arrest specific 2-like protein 1 expression is upregulated in podocytes through advanced glycation end-products.

Growth arrest specific 2-like protein 1 (GAS2L1) protein is a member of the GAS2 family of proteins, known to regulate apoptosis and cellular cytoskeleton reorganization in different cells. Recently we identified that Gas2l1 gene expression in podocytes is influenced by advanced glycation end product-bovine serum albumin(AGE-BSA). The study was performed employing cultured podocytes and diabetic ( db/db ) mice, a model of type 2 diabetes. Akbuminuria as wellas urinary neutrophil gelatinase-associated lipocalin (NGAL) excretion as measured with specific ELISAs. Gene expression was analysed via semiquantitative and real-time polymerase chain reaction. The protein levels were determined by western blotting and immunostaining. We found that the Gas2l1 α isoform is expressed in podocytes. Treatment with AGE-BSA induced Gas2l1 α and Gas2 mRNA levels compared with controls incubated with non-glycated control BSA (Co-BSA). Moreover, application of the recombinant soluble receptor of AGEs (sRAGE), a competitor of cellular RAGE, reversed the AGE-BSA effect. Interestingly, AGE-BSA also increased the protein levels of GAS2L1α in a RAGE-dependent manner, but did not affect the GAS2 expression. Periodic acid-Schiff staining and albuminuria as well as urinary NGAL excretion revealed that db/db mice progressively developed diabetic nephropathy with renal accumulation of N ε -carboxy-methyl-lysine (immunohistochemistry, western blots). Analyses of GAS2L1α and GAS2 proteins in diabetic mice revealed that both were significantly elevated relative to their non-diabetic littermates. In addition, GAS2L1α and GAS2 proteins positively correlated with the accumulation of AGEs in the blood plasma of diabetic mice and the administration of sRAGE in diabetic mice reduced the glomerular expression of both proteins. We show for the first time that the protein expression of GAS2L1α in vitro and in vivo is regulated by the AGE-RAGE axis. The suppression of AGE ligation with their RAGE in diabetic mice with progressive nephropathy reversed the GAS2L1α expression, thus suggesting a role of GAS2L1α in the development of diabetic disease, which needs to be further elucidated.

Independent associations of urine neutrophil gelatinase&amp;ndash;associated lipocalin and serum uric acid with interstitial fibrosis and tubular atrophy in primary glomerulonephritis

The degree of interstitial fibrosis and tubular atrophy (IFTA) is one of the strongest prognostic factors in glomerulonephritis (GN). In experimental models, high serum uric acid (UA) could contribute to IFTA through direct effects on the renal tubules, but the significance of this process has not been evaluated in patients. Urine neutrophil gelatinase–associated lipocalin (NGAL) is produced by renal tubules following acute or chronic damage. We investigated the relationship between UA and NGAL excretion in primary GN and tested whether these biomarkers are independently associated with IFTA. Urine and blood were collected from patients on the day of kidney biopsy. IFTA was assessed semi-quantitatively. Fifty-one patients with primary GN were enrolled. NGAL/creatinine correlated significantly with proteinuria but not with glomerular filtration rate (GFR). By contrast, UA correlated with GFR but not with proteinuria. NGAL/creatinine did not correlate with UA. Both NGAL/creatinine and UA increased with the severity of IFTA. By multivariate analysis, GFR, NGAL/creatinine, and UA were independently associated with moderate-to-severe IFTA. Combining UA and NGAL/creatinine with classical predictors (proteinuria and GFR) tended to improve discrimination for moderate-to-severe IFTA. Findings that UA was unrelated to urinary NGAL excretion suggest that the two biomarkers reflect different pathways related to the development of IFTA in primary GN. Both NGAL/creatinine and UA were independently associated with moderate-to-severe IFTA.

Mild systemic thermal therapy ameliorates renal dysfunction in a rodent model of chronic kidney disease.

Thermal therapy has become a nonpharmacological therapy in clinical settings, especially for cardiovascular diseases. However, the practical role of thermal therapy on chronic kidney disease remains elusive. We performed the present study to investigate whether a modified thermal protocol, repeated mild thermal stimulation (MTS), could affect renal damages in chronic kidney disease using a mouse renal ablation model. Mice were subjected to MTS or room temperature (RT) treatment once daily for 4 wk after subtotal nephrectomy (Nx) or sham operation (Sh). We revealed that MTS alleviated renal impairment as indicated by serum creatinine and albuminuria in Nx groups. In addition, the Nx + MTS group showed attenuated tubular histological changes and reduced urinary neutrophil gelatinase-associated lipocalin excretion approximately by half compared with the Nx + RT group. Increased apoptotic signaling, such as TUNEL-positive cell count and cleavage of caspase 3, as well as enhanced oxidative stress were significantly reduced in the Nx + MTS group compared with the Nx + RT group. These changes were accompanied with the restoration of kidney Mn-SOD levels by MTS. Heat shock protein 27, a key molecular chaperone, was phosphorylated by MTS only in Nx kidneys rather than in Sh kidneys. MTS also tended to increase the phosphorylation of p38 MAPK and Akt in Nx kidneys, possibly associated with the activation of heat shock protein 27. Taken together, these results suggest that modified MTS can protect against renal injury in a rodent model of chronic kidney disease.

Renal injury during hip fracture surgery: an exploratory study.

The present observational study was undertaken to identify potential markers of poor outcome, such as renal failure and mortality, after hip fracture surgery. Forty-three patients, with a mean age of 78 years, were studied having undergone acute hip fracture surgery. Analysis included the urinary excretion of cortisol, albumin and sodium. The degree of fluid retention was evaluated based on the urinary excretion of metabolic end products. Fluid retention and the excretion of albumin and neutrophil gelatinase-associated lipocalin (NGAL) were measured repeatedly in a sub-group of 15 patients who also underwent haemodynamic monitoring. The perioperative change in serum creatinine and a 30-day mortality served as outcome measures. Although serum creatinine increased by > 25% in 21% of the patients, only a high preoperative creatinine concentration correlated with a 30-day mortality. The subgroup analysis revealed that fluid retention was pronounced and remained essentially unchanged up to the first postoperative day. A rise in serum creatinine was always preceded by increased urinary excretion of NGAL that, in turn, was associated with preoperative fluid retention. The only perioperative event that correlated with a higher 30-day mortality was perioperative aggravation of albuminuria (67% vs 0%, P < 0.01), which became more common with advanced age and a low cardiac index. Two different mechanisms seem to affect the kidneys during hip fracture surgery. The first elevates the serum creatinine concentration while the second increases the albuminuria. Only the second mechanism had a bearing on mortality.

Tubular Injury Biomarkers to Detect Gentamicin-Induced Acute Kidney Injury in the Neonatal Intensive Care Unit

We evaluated whether urinary excretion of tubular injury markers could be useful for early detection of gentamicin (GM)-induced renal damage in neonates. We conducted a prospective, observational trial in neonates admitted to the neonatal intensive care unit (26 GM treated, 20 control). Kidney injury molecule-1 (KIM-1), neutrophil gelatinase-associated lipocalin (NGAL), N-acetyl-β-D-glucosaminidase (NAG), and π- and α-glutathione-S-transferase (GSTP1-1 and GSTA1-1) were measured every 2 hours during admission and compared with serum creatinine (sCr) and urine output. Nine neonates developed AKI during the course of the study. The peak in excretion of urinary biomarkers preceded the peak in sCr (p < 0.0001). GM administration resulted in a more pronounced increase of sCr compared with control (13 [12-28] vs. 10 µmol/L [8.5-17]; p < 0.05). The urinary excretion of NAG (178 [104-698] vs. 32 ng/mol Cr [9-82]; p < 0.001) and NGAL (569 [168-1,681] vs. 222 ng/mol Cr [90-497]; p < 0.05) was higher in the GM group compared with control and preceded the peak of sCr and urine output decrease. GM administration to neonates is associated with renal damage reflected by a more pronounced increase in sCr preceded by urinary excretion of biomarkers. Urinary biomarkers may be useful for earlier identification of renal injury in neonates.

Protection of Wistar-Furth rats against postischaemic acute renal injury: role for nitric oxide and thromboxane?

The Wistar-Furth (WF) rat strain is usually used in models of full major histocompatibility complex-mismatched kidney transplantation. Because these rats have been demonstrated to be resistant to several models of chronic kidney disease, the aim of the present study was to investigate their potential resistance to renal ischaemia-reperfusion (I/R) injury compared with another strain, namely Wistar-Hanover (WH) rats. Anaesthetized male WH and WF rats were submitted to I/R by occlusion of the left renal artery and contralateral nephrectomy. Urine, blood and tissue samples were collected at different time points after I/R to evaluate renal function, inflammation and tubular injury, along with determination of nitric oxide synthase (NOS) expression and thromboxane A2 (TxA2 ) production. Post-ischaemic renal function was better preserved in WF than WH rats, as evidenced by reduced levels of creatininaemia, urinary neutrophil gelatinase-associated lipocalin excretion and proteinuria. In addition, WF rats had less intrarenal inflammation than WH rats after I/R injury. These observations were associated with maintenance of neuronal NOS expression, along with lower induction of inducible NOS expression in WF versus WH rats. Moreover, WF rats excreted a significantly lower amount of TxB2 . The results indicate that WF rats are more resistant to an I/R injury than WH rats in terms of renal function and inflammation. These observations are associated with differential regulation of intrarenal NOS expression, as well as a reduction in thromboxane production, which could contribute to a better outcome for the postischaemic kidney in WF rats.

Early Urinary and Plasma Biomarkers for Experimental Diabetic Nephropathy

As the prevalence of diabetes rises, its complications such as diabetic nephropathy affect an increaseing number of patients. Consequently, the need for biomarkers in rodent models which reflect the stage and course of diabetic nephropathy is high. This article focuses on Heart-type fatty acid binding protein (H-FABP), osteopontin (OPN), nephrin, and Neutrophil gelatinase-associated lipocalin (NGAL) in urine, and kidney injury molecule (KIM)-1, clusterin, and tissue inhibitior of metalloproteinases (TIMP) 1 in plasma in uni-nephrectomized rats with streptocotozin-induced type 1 diabetes mellitus, a common animal model to explore renal impairment in the setting of diabetes mellitus. 23 male Wistar rats were uni-nephrectomized and subsequently divided into two study groups. The diabetic group received streptozotocin (STZ) via tail-vein injection, the non-diabetic group received citrate buffer without STZ. Subsequently, blood glucose, body weight, and blood pressure were checked regularly. After 18 weeks, animals were placed in metabolic cages, blood and urine obtained and subsequently organs were harvested after sacrifice. Blood glucose levels were highly increased in diabetic animals throughout the experiment, whereas systolic blood pressure did not differ between the study groups. At study end, classical biomarkers such as urinary albumin and protein and plasma cystatin c were only slightly but not significantly different between groups indicating a very early disease state. In contrast, urinary excretion of H-FABP, OPN, nephrin, and NGAL were highly increased in diabetic animals with a highly significant p-value (p < 0.01 each) compared to non-diabetic animals. In plasma, differences were found for calbindin, KIM-1, clusterin, TIMP-1, and OPN. These findings were confirmed by means of the area under the receiver operating characteristic curve (ROC-AUC) analysis. In summary, our study revealed elevated levels of new plasma and urinary biomarkers (urinary osteopontin, urinary nephrin, urinary NGAL, urinary H-FABP, plasma KIM-1, plasma TIMP-1) in uni-nephrectomized diabetic rats, an established rat model of diabetic nephropathy. These biomarkers appeared even before the classical biomarkers of diabetic nephropathy such as albuminuria and urinary protein excretion. The new biomarkers might offer an advantage to urinary albumin and plasma cystatin c with respect to early detection.

Evaluation of urine biomarkers of kidney injury in polycystic kidney disease

Progressive disruption of renal tubular integrity in the setting of increased cellular proliferation and apoptosis is a feature of ADPKD. Here we evaluated the effect of these processes on the expression of NGAL and IL-18, markers of tubular injury, in rodent models and in the cyst fluid and urine of patients with ADPKD. Two mouse models where Pkd2 was inactivated which resulted in early or adult onset cysts, were used to evaluate NGAL levels. Further, the Han:SPRD rat model of polycystic disease was used to study IL-18 levels. In four annual serial urine samples from 107 patients with ADPKD in the Consortium for Radiologic Imaging for the Study of Polycystic Kidney Disease (CRISP) study, NGAL and IL-18 excretion rates were determined in conjunction with measures of total kidney volume and estimated GFR (eGFR) by the MDRD equation. Kidneys from affected mice and rats showed prominent expression of NGAL and IL-18/IL-18R, respectively, in epithelial cells lining kidney cysts. In human ADPKD cyst fluid, both NGAL and IL-18 were elevated. In CRISP patients, the mean percentage increase in total kidney volume was 5.4 /year and the mean decline in eGFR 2.4 mL/min/year. The trend of increased mean urine NGAL and IL-18 over three years was statistically significant; however, there was no association of tertiles of IL-18 or quartiles of NGAL and the change in total kidney volume or eGFR over this period. Thus, urinary NGAL and IL-18 excretion are mildly and stably elevated in ADPKD, but do not correlate with changes in total kidney volume or kidney function. This may be due, in part, to the lack of communication between individual cysts and the urinary collecting system in this disorder.

Urinary Neutrophil Gelatinase-Associated Lipocalin Is a Potential Biomarker for Renal Damage in Patients with Systemic Lupus Erythematosus

Neutrophil gelatinase-associated lipocalin (NGAL) has been demonstrated to be a novel biomarker in acute and chronic kidney disease. We hypothesized that 24-hour urinary NGAL excretion may be a predictor for renal damage in patients with systemic lupus erythematosus (SLE). Thirty-four SLE patients with renal involvement (SLE-renal group), 8 SLE patients without renal involvement (SLE-nonrenal group), 14 patients with non-SLE autoimmune diseases (disease control or DC group), and 12 healthy volunteers (normal control or NC group) were compared for 24-hour urinary excretion of NGAL and different cytokines. We found that the 24-hour urinary NGAL excretion in the SLE-renal group was higher than that in the SLE-non-renal, DC, and NC groups. However, the excretion of interleukin-10, transforming growth factor-β1, and tumor necrosis factor-α was not different between the SLE-renal and SLE-non-renal groups. Furthermore, NGAL excretion in the SLE-renal group was correlated with serum creatinine levels and creatinine clearance, but not with the SLE Disease Activity Index score. Multivariate logistic regression analysis and receiver operating characteristic curve analysis revealed that 24-hour urinary NGAL excretion is a potential biomarker for renal damage in SLE patients, with higher sensitivity and specificity than anti-dsDNA antibody titers.

Urinary transforming growth factor beta-1 as a marker of renal dysfunction in sickle cell disease

Renal dysfunction affects 5-18% of patients with sickle cell disease (SCD). To date, no studies have described urinary levels of transforming growth factor β-1 (TGF-β1), a marker of fibrosis, and neutrophil gelatinase-associated lipocalin (NGAL), a marker of acute/chronic kidney disease, as biomarkers in identifying patients at risk of developing renal disease in SCD. We hypothesized that SCD subjects will have increased urinary excretion of TGF-β1 and NGAL compared with healthy controls (CTR). We examined 51 SCD subjects: 42 HbSS, 8 HbSC, and 1 HbSD. Sixteen out of 42 patients with HbSS were on hydroxyurea (HU). Urinary excretion of TGF-β1 was 26.4 ± 1.5 pg/mgCr in SCD subjects vs 15.0 ± 2.4 pg/mgCr in CTR (p<0.00001). SCD patients with hemoglobin < 9 g/dl had higher urinary TGF-β1 than patients with milder anemia (p=0.002). Urinary TGF-β1 trended lower in HbSS patients treated with HU (23.61 ± 2.6 pg/mgCr), vs patients not on HU (27.69 ± 1.8 pg/mgCr; p=0.055). There was no correlation between urinary TGF-β1 and microalbuminuria or estimated glomerular function. There was no difference in urinary NGAL in SCD patients vs CTR. We suggest that urinary TGF-β1 may serve as a marker of early renal injury in SCD.

Predicting Cisplatin-Induced Acute Kidney Injury by Urinary Neutrophil Gelatinase-Associated Lipocalin Excretion: A Pilot Prospective Case-Control Study

Background/Aims: Nephrotoxicity is the major limitation to cisplatin therapy for solid tumors. We aimed at evaluating whether early increases in serum/urine levels of neutrophil gelatinase-associated lipocalin (NGAL), a biomarker of tubular damage and regeneration, predict cisplatin-induced acute kidney injury (AKI). Methods: We compared changes in serum creatinine and serum/urine NGAL levels (ELISA assay) at 1 and 4 h and 1, 2, 3, 7 and 15 days after cisplatin infusion (70–80 mg/m²) versus baseline in 12 consecutive cancer patients (cases) with AKI (>25% serum creatinine increase vs. baseline) and 12 consecutive controls without AKI. Results: Baseline characteristics and posttreatment serum NGAL levels were similar in both groups. Urinary NGAL levels increased significantly more in cases than in controls at 1, 2, 3 and 15 days after cisplatin. The NGAL increase preceded AKI by 4.5 days and the NGAL increase at day 2 after cisplatin independently predicted AKI (p < 0.05). Six cases with residual kidney dysfunction at 15 days showed a trend to earlier and higher increase in urinary NGAL levels compared to cases with renal function recovery. Conclusion: An early increase in urinary NGAL excretion may help in identifying patients at risk of cisplatin-induced AKI who might benefit from innovative treatments to prevent cisplatin nephrotoxicity.

Disease and gender-specific dysregulation of NGAL and MMP-9 in type 1 diabetes mellitus

Neutrophil gelatinase-associated lipocalin (NGAL), a biomarker of renal injury, can bind matrix metalloproteinase-9 (MMP-9) and inhibit its degradation, thereby sustaining MMP-9 proteolytic activity. MMP-9 is produced by renal podocytes, and podocyte MMP production can be modified by high ambient glucose levels. Moreover, dysregulation of MMP-9 activity, gene expression, or urine concentrations has been demonstrated in T2DM-associated nephropathy and in non-diabetic proteinuric renal diseases. Our objective was to determine whether NGAL/MMP-9 dysregulation might contribute to or serve as a biomarker of diabetic nephropathy in type 1 DM (T1DM). Plasma MMP-9, and urine NGAL and MMP-9 concentrations were measured in 121 T1DM and 55 control subjects and examined relative to indicators of glycemia, renal function, and degree of albuminuria. T1DM was associated with a significant increase in urinary excretion of both NGAL and MMP-9, and urine NGAL:Cr (NGAL corrected to urine creatinine) and urine MMP-9:Cr concentrations were highly correlated with each other. Both were also positively correlated with measurements of glycemic control and with albuminuria. Plasma MMP-9, urine MMP-9, and urine NGAL concentrations were significantly higher in females compared to males, and urine MMP-9:Cr concentrations displayed a menstrual cycle specific pattern. Increased urinary excretion of NGAL and MMP-9 supports a role for NGAL/MMP-9 dysregulation in renal dysfunction; moreover, gender-specific differences could support a gender contribution to pathological mechanisms or susceptibility for the development of renal complications in diabetes mellitus.