Urine NGAL and IL-18 are predictive biomarkers for delayed graft function following kidney transplantation

Normalisation of urinary biomarkers to creatinine for clinical practice and research--when and why

Acute kidney injury (AKI) and chronic kidney disease (CKD) are major health problems. Urinary biomarkers have both diagnostic and prognostic utility in AKI and CKD. However, how biomarker excretion rates should be reported, especially whether they should be normalised to urinary creatinine concentration (uCr), is controversial. Some studies suggest that normalisation to uCr may be inappropriate at times, as urinary creatinine excretion rate may vary greatly, depending on the situation. Notably, recent studies suggest that while normalisation of values to UCr may be valid for the evaluation of CKD and prediction of AKI sequelae and occurrences, it could be inappropriate for the diagnosis of AKI, or in the presence of certain acute kidney disease states.

Comparative assessment of neutrophil gelatinase-associated lipocalin (NGAL) and cystatin C as early biomarkers for early detection of renal failure in patients with hypertension

BACKGROUND

Hypertension is one the most common causes of chronic kidney disease (CKD). One of the major concerns in hypertensive patients is early detection of renal disorders. In the past, serum creatinine (Scr) concentration was used as a marker of kidney function, but it proffers a late reflection of reduced glomerular filtration rate. Cystatin C and neutrophil gelatinase-associated lipocalin (NGAL) have been recently proven to be useful for quantification of CKD. Therefore, we compared the diagnostic value of NGAL with cystatin C and creatinine to evaluate kidney function in hypertensive patients.

METHODS

In this study, 42 hypertensive patients and 30 healthy volunteers were recruited. Serum cystatin C (Scys C) and plasma NGAL were measured using ELISA method. Creatinine, urea, hemoglobin, fibrinogen, and C-reactive protein were measured according to the routine methods. Estimated glomerular filtration rate (eGFR) was considered as the gold standard method (cut-off value of < 78 ml/min/1.73 m².

RESULTS

In the patient group, plasma NGAL, cystatin C, and creatinine were all significantly correlated with eGFR, and plasma NGAL correlated best with eGFR. Receiver-operating characteristics analysis indicated that plasma NGAL was a better indicator than creatinine and cystatin C for predicting a GFR < 78 ml/min/1.73 m2. The sensitivity and specificity for NGAL were 96% and 100%, for cystatin C were 92% and 60% and for creatinine were 76% and 47%, respectively.

CONCLUSION

Plasma NGAL demonstrated a higher diagnostic value to detect kidney impairment in the early stages of CKD as compared to Scys C and Scr in hypertensive patients.

Biomarkers of calcineurin inhibitor nephrotoxicity in transplantation

Over 35 years of use has demonstrated the revolutionary therapeutic benefits of calcineurin inhibitors (CNI) in not only preventing transplant rejection, but also the renal and nonrenal toxicity of CNI. Acute reversible and insidious irreversible forms of CNI nephrotoxicity have been identified, with ischemia from an imbalance between vasoconstrictors and vasodilators playing an important role. The ongoing search to define toxicity pathways has been enriched by ‘Omics’ studies. Changes in proteins including those involved in activation of pro-inflammatory responses, oxidative stress, ER stress and the unfolded protein response have been identified, and these may serve as biomarkers of toxicity. However, the current standard of CNI toxicity, histology, lacks specificity, which creates challenges for biomarker validation. This review focuses on progress in nephrotoxic pathway identification of CNI and biomarker validation.

Neutrophil gelatinase-associated lipocalin as a marker of acute renal disease

PURPOSE OF REVIEW

Acute renal disease has major prognostic impact in hospitalized patients. Early diagnosis using renal function markers such as serum creatinine or urinary output and effective treatment are currently not possible. This review focuses on recent studies examining the biological characteristics and the diagnostic and prognostic value of a novel biomarker, neutrophil gelatinase-associated lipocalin (NGAL), in patients at risk for acute renal disease.

RECENT FINDINGS

NGAL levels increase early and proportional to the degree of renal injury in the urine and plasma. Here, we report the results of clinical studies where NGAL was measured in 325 patients with autoimmune and infectious diseases, those with cisplatin-associated nephrotoxicity, and more than 4000 patients at risk of acute kidney injury due to sepsis, cardiac surgery, exposure to contrast media, or after renal transplantation. Whenever renal damage occurred, as evidenced by histopathology or subsequent increase in serum creatinine levels, NGAL levels were higher than in patients without acute renal disease. An increase in NGAL substantially preceded clinical diagnosis of acute renal disease.

SUMMARY

NGAL fulfills many characteristics of an appropriate 'real-time' renal biomarker. The data on NGAL could justify re-assessment of the concept and definition of acute kidney injury.

The dose-related effects of dexmedetomidine on renal functions and serum neutrophil gelatinase-associated lipocalin values after coronary artery bypass grafting: a randomized, triple-blind, placebo-controlled study

OBJECTIVES

Acute kidney failure after coronary artery bypass grafting (CABG) is a serious complication that increases morbidity and mortality rates. Early detection and prevention of this complication are very important. A novel biomarker named neutrophil gelatinase-associated lipocalin (NGAL) can play an important role in early diagnosis of acute kidney injury. Recent studies on the favourable effects of Dexmedetomidine on cardiac surgery have been published. The aim of this study is to investigate whether there is a dose-dependent positive effect of Dexmedetomidine on neutrophil gelatinase-associated lipocalin levels and renal functions when used after CABG.

METHODS

Our randomized, triple-blinded, placebo-controlled study was conducted among 295 patients scheduled for CABG surgery between August 2009 and March 2011 in a tertiary cardiac and vascular surgery clinic. A total of 90 consecutive patients who met inclusion criteria were randomized and divided into three groups. The first group received a placebo. The second and the third groups received 4 and 8 µg/cc concentration of the Dexmedetomidine infusion, respectively. Infusion rates were regulated to obtain sedation with a Ramsey sedation score of 2 or 3. Patients were regrouped according to the total Dexmedetomidine dose. Statistical analyses of variables including serum neutrophil gelatinase-associated lipocalin values and conventional renal function tests were made for all six possibilities before the blind was broken.

RESULTS

Results of conventional renal function tests were not significantly different. However, neutrophil gelatinase-associated lipocalin levels for the first postoperative day for placebo, low-dose and high-dose Dexmedetomidine groups were 176.8 ± 145.9, 97.7 ± 63.4 and 67.3 ± 10.9 ng/ml, respectively. These values were significantly different among the groups (P <0.001).

CONCLUSIONS

In our study, we found that Dexmedetomidine infusion for sedation after CABG under cardiopulmonary bypass can be useful in the prevention of kidney injury. Conventional renal function tests, including blood urea nitrogen, serum creatinine, urine output and creatinine clearance rate measurements typically may not detect the development of acute kidney dysfunction in the first 48-h postoperative period. Differences were detected in renal function in the early postoperative period and the development of acute kidney injury, as determined by measurements of blood NGAL levels, was significant and dose-dependent.

Biomarkers and physiopathology in the cardiorenal syndrome

Acute cardiorenal syndrome (CRS) corresponds to an association of acute heart failure and a worsening of renal function. The detection of acute kidney injury (AKI) unfortunately occurs at a late stage of CRS, leading to an increased mortality of the patients. In this review, we described the pathophysiology of CRS and discussed the potential interest of biochemical biomarkers (namely creatinine, cystatin C, NGAL, KIM-1, fatty acid binding protein, Nacetyl-β-D-glucosaminidase and IL-18) that could potentially help to detect AKI earlier and thus reduce the morbi-mortality of the patients suffering from CRS.

Is plasma and urine neutrophil gelatinase-associated lipocalin (NGAL) determination in donors and recipients predictive of renal function after kidney transplantation?

OBJECTIVES

Delayed graft function (DGF) is still a major issue in kidney transplantation. Plasma and urine neutrophil gelatinase-associated lipocalin (NGAL) were evaluated in a population of kidney donors and recipients to investigate their performance to predict early renal function.

DESIGN AND METHODS

Plasma (pNGAL) and urine (uNGAL) samples were obtained from donors before organ procurement, and from recipients before transplantation, and then 6, 24 and 48h after the procedure. Kidney transplantations were performed from both living donors (LDs, n=17) and deceased donors (DDs, n=80). Recovery of renal function was evaluated as the time to reach serum creatinine <2mg/l or glomerular filtration rate (GFR)>40mL/min. Logistic regression was used to assess the ability of different variables to predict the occurrence of DGF.

RESULTS

Plasma NGAL levels were significantly lower in LDs than in DDs. No episodes of DGF were recorded among LD kidney recipients, but DGF was observed in 25% of patients in the DD group. There was no correlation between donor pNGAL and uNGAL values and the occurrence of post-transplant DGF. Recipient pNGAL performed better than uNGAL in terms of predicting DGF occurrence. Donor pNGAL and uNGAL values did not influence the time needed to reach serum creatinine levels of <2mg/dl after transplantation. When time to reach eGFR of >40mL/min is considered, only donor uNGAL seems to be a predictor of graft function recovery. However, recipient pNGAL values obtained 24 and 48h after transplantation, but not uNGAL values, were found to be a significant predictor of graft function recovery.

CONCLUSIONS

Plasma NGAL level determination in recipients, but not in donors, proved to be a reliable predictor of DGF occurrence and renal function restoration, but too long for an interval to be able to compete with biomarkers currently used in clinical practice.

Urinary interleukin-18 as an early indicator to predict contrast-induced nephropathy in patients undergoing percutaneous coronary intervention

Contrast-induced nephropathy (CIN) is at present the third leading cause of hospital-acquired acute kidney injury (AKI). Traditionally, it is diagnosed by measuring an increase of the serum creatinine (SCr) concentration. However, SCr is an insensitive marker for detecting CIN. This study was designed to investigate whether human urinary interleukin-18 (IL-18) is early predictive marker for CIN following coronary interventional procedures. The general clinical data of 180 patients who underwent coronary interventional procedures at the Department of Cardiology, Affiliated Hospital of Xuzhou Medical College from March 1, 2012 to September 31, 2012 were collected. A nonionic, low osmolality contrast agent was used in the laboratory at this time. SCr values and estimated glomerular filtration rate (eGFR) were measured prior to and within 24 and 48 h after the administration of contrast agents. Urine samples were collected prior to and 2, 6, 12, 24 and 48 h after the coronary interventional procedure, and urinary IL-18 levels were measured using an ELISA kit. CIN was defined as an increase of ≥0.5 mg/dl or ≥25% in SCr concentration over baseline 24–48 h after the procedure. CIN occurred in 16 of 180 (8.9%) patients. The levels of urinary IL-18 measured 2 h after the procedure were increased in the CIN group, but the increase was not significant (P>0.05). There were significant differences (P<0.05) between the urinary IL-18 levels 6, 12, 24 and 48 h after the procedure and those before the procedure. No significant difference was identified between the SCr levels measured prior to and 24 h after the procedure. The area under the receiver operating characteristic (ROC) curve of urinary IL-18 12 h after the procedure was 0.811 and the 95% confidence interval of the area under the curve was 0.735–0.888. If the critical point of the diagnosis of CIN was 815.61 pg/ml, the sensitivity was 87.5% and the specificity was 62.2%. Univariate analysis indicated that the urinary IL-18 level was positively correlated with the SCr concentration pre- and postprocedure. In conclusion, urinary IL-18 may be a promising indicator for the early prediction of CIN.

Acute kidney injury after using contrast during cardiac catheterization in children with heart disease

Acute kidney injury (AKI) is closely associated with the mortality of hospitalized patients and long-term development of chronic kidney disease, especially in children. The purpose of our study was to assess the evidence of contrast-induced AKI after cardiac catheterization in children with heart disease and evaluate the clinical usefulness of candidate biomarkers in AKI. A total of 26 children undergoing cardiac catheterization due to various heart diseases were selected and urine and blood samples were taken at 0 hr, 6 hr, 24 hr, and 48 hr after cardiac catheterization. Until 48 hr after cardiac catheterization, there was no significant increase in serum creatinine level in all patients. Unlike urine kidney injury molecule-1, IL-18 and neutrophil gelatinase-associated lipocalin, urine liver-type fatty acid-binding protein (L-FABP) level showed biphasic pattern and the significant difference in the levels of urine L-FABP between 24 and 48 hr. We suggest that urine L-FABP can be one of the useful biomarkers to detect subclinical AKI developed by the contrast before cardiac surgery.

Biomarkers in cardiorenal syndromes

Cardiac and renal diseases often coexist and patients with cardiac and renal failure have high morbidity and mortality. Cardiorenal syndromes (CRSs) are disorders of the heart and kidneys whereby dysfunction in one organ may induce dysfunction in the other organ. Five subtypes of CRSs have been defined by the Acute Dialysis Quality Initiative Consensus Group. There is a need for early detection and monitoring of patients with CRSs. Biomarkers play a key role in the diagnosis and monitoring of acute myocardial infarction, chronic heart failure, and chronic kidney disease. In recent years, new biomarkers have been identified that may play a role in the early diagnosis of acute kidney injury. Herein, we review the use of serum and urine biomarkers in the diagnosis and management of CRSs. The established cardiac and renal biomarkers such as the cardiac troponins, natriuretic peptides, urine albumin, and creatinine, as well as the new renal biomarkers cystatin C and neutrophil gelatinase-associated lipocalin are reviewed in detail. The recent advances in assay methods, clinical studies, and recommendations in clinical guidelines are discussed. With advances in biomarker research, in future, perhaps a multimarker approach will become feasible to stratify the diagnosis of CRS for individualized treatment and prognosis.

Serum neutrophil gelatinase-associated lipocalin and recovery of kidney graft function after transplantation

Background

Neutrophil gelatinase-associated lipocalin (NGAL) is a marker for acute kidney injury. We studied whether serum NGAL predicts delayed graft function (DGF) and recovery of kidney function after transplantation.

Methods

Serum NGAL was analyzed using commercial ELISA and point-of-care (POC) (Triage®, Biosite) methods. Serum samples were collected from 176 consecutive, deceased-donor kidney recipients just before transplant surgery and on day 1 and 14 after transplantation. The first 132 samples were analyzed with both methods and the remaining samples with the POC method.

Results

The correlation between the ELISA and POC methods was 0.89, p < 0.0001 and hence the POC method was used for the remaining analyses. DGF was seen in 66/176 patients. Day 1 sNGAL was significantly higher in DGF (588 ng/ml, SD 189.6) compared to early graft function (355 ng/ml, SD 166.2, p < 0.0001) and this difference persisted on day 14. Day 1 sNGAL predicted DGF with an area under the curve (AUC) of 0.853 (CI 0.792-0.914, p < 0.0001). At the optimal cutoff level of 423 ng/ml the sensitivity was 87% and the specificity 77%. In a multivariate analysis, day 1 sNGAL emerged as an independent predictor of DGF. The sNGAL also predicted DGF lasting longer than 14 days with an AUC of 0.825 (CI 0.751-0.899, p < 0.0001). At the optimal cutoff level of 486 ng/ml, the sensitivity was 80% and specificity 75%.

Conclusion

Serum NGAL predicts clinically significant DGF and is useful in the care of kidney transplant recipients.

Evaluation of renal function using the level of neutrophil gelatinase-associated lipocalin is not predictive of nephrotoxicity associated with cisplatin-based chemotherapy

BACKGROUND

For early detection of renal damage during the usage of cisplatin based chemotherapy, changes in renal function should be monitored carefully. In recent years, neutrophil gelatinase-associated lipocalin, a small polypeptide molecule, has shown promise as a marker of acute renal failure. The aim of this present study was to assess possible risk prediction of cisplatin-induced nephrotoxicity using serum NGAL.

MATERIALS AND METHODS

A total of 34 consecutive patients with documented serum creatinine at least 24 hours before every cycle of cisplatin-based chemotherapy were included in the study. Demographic and medical data including age, performance status, tumor characteristics and comorbid diseases were collected from medical charts. Renal function was evaluated at least 48 hours before the treatment and at the end of the treatment based on the Modification of Diet in Renal Disease (MDRD) formula. Before and after cisplatin infusion serum NGAL levels were measured for the first and 3rd cycles of chemotherapy.

RESULTS

The median age of the study population was 54 (32-70) years. Fifteen patients (41.1%) were treated on an adjuvant basis, whereas 19 patients (58.9%) were treated for metastatic disease. There was no correlation of serum NGAL levels with serum creatinine (r=0.20, p=0.26) and MDRD (r=-0.12, p=0.50) and creatinine clearance-Cockcroft-Gault (r=-0.22, p=0.22) after cisplatin infusion at the end of the 3rd cycle of chemotherapy.

CONCLUSIONS

In our study, serum NGAL levels were not correlated with the cisplatin induced nephrotoxicity. Further prospective studies are needed to conclude that serum NGAL level is not a good surrogate marker to predict early cisplatin induced nephrotoxicity.

Non-inferiority of creatinine excretion rate to urinary L-FABP and NGAL as predictors of early renal allograft function

Background

We evaluated accuracy of urinary liver type fatty acid-binding protein (L-FABP) for prediction of early allograft function and compared it to neutrophil gelatinase associated lipocalin (NGAL), diuresis and urinary creatinine excretion rate (UCr).

Methods

Urine samples from 71 consecutive patients were taken 4, 10, 24 and 48 h after transplantation. We classified recipients into two groups: immediate graft function (IGF), with more than 70% reduction of serum Cr at 7th day post-transplant, and delayed graft function (DGF)/slow graft function (SGF) group (DGF - the need for hemodialysis procedure in the first week, SGF - less than 70% reduction of serum Cr in the first week).

Results

Thirty-one recipients had IGF and 40 had DGF/SGF. L-FABP was only useful 48 h post-transplant with ROC AUC of 0.85 (95% C.I. 0.74-0.92); NGAL 24 h post-transplant had ROC AUC of 0.82 (0.7-0.91). Sensitivity, specificity, PPV and NPV for prediction of DGF/SGF with L-FABP > 9.5 mg/mmol Cr and NGAL > 33.1 μg/mmol Cr were: 86, 80, 83 and 83% (L-FABP), and 68, 93, 91, and 73% (NGAL). The difference in urine output between the groups was largest 4 h post-transplant (p = 0.001), later on the difference diminished. There were no significant differences in ROC AUC between L-FABP at 48 h, NGAL at 24 h, urine output at 4 h and UCr excretion rate at 10 h post-transplant. UCr < 0.56 mmol/h 10 h post-transplant predicted DGF/SGF with 94% sensitivity, 84% specificity, 89% PPV and 91% NPV, ROC AUC was 0.9. Classification tree with urine output 4 h and UCr 10 h post-transplant accurately predicted 89% of outcomes. When L-FABP or NGAL were added, the prediction was accurate in 92 or 90%, respectively.

Conclusions

L-FABP is comparable to NGAL for prediction of first week allograft function, however UCr and diuresis were non-inferior.

Serum and urinary NGAL but not KIM-1 raises in human postrenal AKI

BACKGROUND

We examined the value of the novel acute kidney injury (AKI) markers neutrophil gelatinase-associated lipocalin (NGAL) and kidney injury molecule-1 (KIM-1) in acute postrenal impairment. These biomarkers have been evaluated in prerenal and intrarenal AKI so far, but not in human acute postrenal kidney injury. With regard to multimorbid and critically ill patients the discrimination of different AKI origins often remains a challenge. As the trend goes towards a diagnostic panel of AKI markers, we hereby aim to contribute to evaluate further options of discrimination in an observational case-control study.

MATERIALS AND METHODS

Blood and urine samples were obtained from 53 patients with acute obstructive nephropathy secondary to ureteral calculi and 52 age-matched healthy controls. Serum NGAL (sNGAL), urinary NGAL (uNGAL) and urinary KIM-1 (uKIM-1) levels were determined using a commercially available ELISA kit, creatinine applying the Jaffé's method.

RESULTS

While urinary levels of KIM-1 were not significantly different between patients with obstructive nephropathy and controls, a striking increase in sNGAL (P < 0·001) and uNGAL (P < 0·01) levels was detected in the obstructive nephropathy group. Within the obstructive nephropathy group, sNGAL (P = 0·01) and uNGAL (P = 0·049) but not uKIM-1 correlated positively with the white blood cell count and uNGAL correlated positively (P = 0·002) with the extent of leucocyturia.

CONCLUSIONS

High levels of sNGAL and uNGAL observed in stone-induced acute obstructive nephropathy may represent a valuable marker of postrenal AKI. Low uKIM-1 levels may help to discriminate postrenal AKI events using a panel of markers in this setting.

Urinary neutrophil gelatinase-associated lipocalin and the occurrence of delayed graft function after kidney transplant

OBJECTIVES

To investigate the predictive value of urinary neutrophil gelatinase-associated lipocalin in the occurrence of delayed graft function after kidney transplant.

MATERIALS AND METHODS

In this prospective cohort study of 67 consecutive patients who received a living-related (40 patients [61%]) or deceased-donor kidney transplant (27 patients [39%]), urinary neutrophil gelatinase-associated lipocalin was determined in the first 100 mL perfusate of the donor kidney and in urine at 6 hours after transplant. Patients were followed (11 ± 7 mo) for changes in estimated glomerular filtration rate and delayed graft function.

RESULTS

The mean urinary neutrophil gelatinase-associated lipocalin level at 6 hours after transplant was significantly higher after deceased-donor (781 ± 452 ng/mL) than living-donor transplant (229 ± 223 ng/mL; P ≤ 0.001). The decrease in estimated glomerular filtration rate from 6 to 12 months after transplant was positively correlated with the urinary neutrophil gelatinase-associated lipocalin levels in the perfusate in living-donor transplant. A significant correlation was noted between the occurrence of delayed graft function and the urinary neutrophil gelatinase-associated lipocalin level at 6 hours after living-donor transplant. In the deceased-donor group, the occurrence of delayed graft function was correlated with urinary neutrophil gelatinase-associated lipocalin levels in the perfusate. In deceased-donor kidney transplant, the mean urinary neutrophil gelatinase-associated lipocalin level in the perfusion fluid was significantly greater from donors who had terminal serum creatinine > 150 μmol/L, and urinary neutrophil gelatinase-associated lipocalin level at 6 hours after transplant was significantly greater in transplants with longer cold ischemia time and donors who had hypertension.

CONCLUSIONS

Urinary neutrophil gelatinase-associated lipocalin levels in the donor kidney perfusate and 6 hours after transplant may be a useful predictor of delayed graft function and decreased graft function from 6 to 12 months after transplant.

α-Intercalated cells defend the urinary system from bacterial infection

α-Intercalated cells (A-ICs) within the collecting duct of the kidney are critical for acid-base homeostasis. Here, we have shown that A-ICs also serve as both sentinels and effectors in the defense against urinary infections. In a murine urinary tract infection model, A-ICs bound uropathogenic E. coli and responded by acidifying the urine and secreting the bacteriostatic protein lipocalin 2 (LCN2; also known as NGAL). A-IC-dependent LCN2 secretion required TLR4, as mice expressing an LPS-insensitive form of TLR4 expressed reduced levels of LCN2. The presence of LCN2 in urine was both necessary and sufficient to control the urinary tract infection through iron sequestration, even in the harsh condition of urine acidification. In mice lacking A-ICs, both urinary LCN2 and urinary acidification were reduced, and consequently bacterial clearance was limited. Together these results indicate that A-ICs, which are known to regulate acid-base metabolism, are also critical for urinary defense against pathogenic bacteria. They respond to both cystitis and pyelonephritis by delivering bacteriostatic chemical agents to the lower urinary system.

Emerging biomarkers and metabolomics for assessing toxic nephropathy and acute kidney injury (AKI) in neonatology

Identification of novel drug-induced toxic nephropathy and acute kidney injury (AKI) biomarkers has been designated as a top priority by the American Society of Nephrology. Increasing knowledge in the science of biology and medicine is leading to the discovery of still more new biomarkers and of their roles in molecular pathways triggered by physiological and pathological conditions. Concomitantly, the development of the so-called "omics" allows the progressive clinical utilization of a multitude of information, from those related to the human genome (genomics) and proteome (proteomics), including the emerging epigenomics, to those related to metabolites (metabolomics). In preterm newborns, one of the most important factors causing the pathogenesis and the progression of AKI is the interaction between the individual genetic code, the environment, the gestational age, and the disease. By analyzing a small urine sample, metabolomics allows to identify instantly any change in phenotype, including changes due to genetic modifications. The role of liquid chromatography-mass spectrometry (LC-MS), proton nuclear magnetic resonance (1H NMR), and other emerging technologies is strategic, contributing basically to the sudden development of new biochemical and molecular tests. Urine neutrophil gelatinase-associated lipocalin (uNGAL) and kidney injury molecule-1 (KIM-1) are closely correlated with the severity of kidney injury, representing noninvasive sensitive surrogate biomarkers for diagnosing, monitoring, and quantifying kidney damage. To become routine tests, uNGAL and KIM-1 should be carefully tested in multicenter clinical trials and should be measured in biological fluids by robust, standardized analytical methods.

Cilostazol renoprotective effect: modulation of PPAR-γ, NGAL, KIM-1 and IL-18 underlies its novel effect in a model of ischemia-reperfusion

Cilostazol, a phosphodiesterase-III inhibitor, reportedly exhibits positive effects against ischemia/reperfusion (I/R)-induced injury in several models. However, its potential role against the renal I/R insult has not been elucidated. To test whether the PPAR-γ (of peroxisome proliferator activated receptor gamma) pathway is involved in the cilostazol effect, rats were randomized into sham, I/R, cilostazol (50 and 100 mg/kg per day, orally), pioglitazone (3 and 10 mg/kg per day, orally) and their combination at the low dose levels. Drugs regimens were administered for 14 days prior to the I/R induction. Pretreatment with cilostazol or pioglitazone provided significant protection against the I/R-induced renal injury as manifested by the attenuated serum levels of creatinine, blood urea nitrogen and cystatin C. Both drugs have also opposed the I/R-induced elevation in tissue contents/activity of neutrophil gelatinase-associated lipocalin (NGAL), kidney injury molecule-1 (Κim-1), nuclear factor-κB, interleuκin-18, caspase-1, as well as malondialdehyde, iNOS, myeloperoxidase, ICAM-1 and VCAM-1. Nevertheless, the drugs increased both the PPAR-γ transcriptional activity and the content of glutathione. Furthermore, combining the two low doses of both drugs produced effects comparable to that of the high dose level of either drug, advocating the fortification of pioglitazone renoprotective effect when given concomitantly with cilostazol. In conclusion, cilostazol purveyed conceivable novel renoprotective mechanisms and alleviated incidents associated with acute renal injury either alone or in combination with pioglitazone partially via the elevation of PPAR-γ besides the amendment of the aforementioned biomarkers.

Serum neutrophil gelatinase associated lipocalin (NGAL) and cystatin C as early predictors of contrast-induced acute kidney injury in patients undergoing percutaneous coronary intervention

BACKGROUND

Contrast-induced acute kidney injury (AKI) is diagnosed by estimating serum creatinine at 48-72h after diagnostic or interventional coronary angiography. It is too late for an early intervention. Neutrophil gelatinase associated lipocalin (NGAL) and cystatin C are novel markers of AKI. We determined the optimum cut-off level of NGAL and cystatin C in early diagnosis and prediction of AKI in patients undergoing coronary angiography followed by angioplasty.

METHODS

In a nested case control study, serum NGAL, cystatin C by ELISA and serum creatinine by Jaffe's kinetic method were estimated at 0, 4, 24 and 48h of coronary angiography followed by angioplasty in 30 cases who developed contrast-induced AKI and 30 subjects who did not develop AKI. eGFR was estimated for both cases and controls by the MDRD equation. ROC was used to determine the optimum cut-off.

RESULTS

Serum NGAL increased sharply at 4h after the procedure and then gradually declined to near normal level at 48h in AKI cases. The rise in cystatin C peaked at 24h and then declined but remained high till 48h. In controls, they remained static. The optimum cut-off of serum NGAL and cystatin C was 155.2ng/ml and 0.517mg/l respectively at 4h and 89.5ng/ml and 0.99mg/l respectively at 24h of angiography. Odds ratio for hypertensives to develop AKI was 3.57 (CI: 1.2-11.1, p=0.03).

CONCLUSION

Serum NGAL and cystatin C may act as early markers of contrast-induced AKI in patients undergoing percutaneous coronary intervention. Patients with hypertension are susceptible to develop contrast-induced AKI.

Near-infrared spectroscopy as continuous real-time monitoring for kidney graft perfusion

BACKGROUND

Near-infrared spectroscopy (NIRS) is a non-invasive technique designed to study regional oxygenation (rSO(2)) by measuring the absorption of chromophores. This study investigated the role of NIRS in the real-time monitoring of kidney graft perfusion for 72 h post-transplantation.

METHODS

Consecutive children undergoing living related donor (LRD) or deceased donor (DD) kidney transplantation (KTP) were prospectively enrolled between April 2010 and August 2011. Renal rSO(2) values were registered continuously for 3 days and correlated with hourly urine output, serum creatinine, and urinary neutrophil gelatinase-associated lipocalin (u-NGAL).

RESULTS

Twenty-four children were included, 6 underwent LRD and 18 DD KTP. Median age was 12.5 years (interquartile range [IQR] 3.5-16.6) and median body weight was 37 kg (IQR 13-49.7). Four patients experienced delayed graft function (DGF). Renal Doppler ultrasound showed normal vascularization patterns in all children. Median basal renal rSO(2) value was 68.8 % (IQR 59.3-76.2), significantly lower than the end-of-period result (83.6 %; IQR 79.2-90.4; p < 0.0001). Renal rSO(2) values showed significant correlation with serum creatinine (rs = -0.62; p < 0.05) and estimated glomerular filtration rate (eGFR) (rs = 0.64; p < 0.05). No correlation was shown between rSO(2) and diuresis. Increased rSO(2) was also found in patients who experienced DGF. u-NGAL exhibited a trend toward a decrease from baseline in both DD and LRD KTPs, with a strong negative correlation with rSO(2).

CONCLUSIONS

rSO(2) assessed by NIRS strongly correlates with common markers of kidney graft function and perfusion, allowing continuous real-time monitoring of blood flow in renal grafts.

Karyopherins: potential biological elements involved in the delayed graft function in renal transplant recipients

Background

Immediately after renal transplantation, patients experience rapid and significant improvement of their clinical conditions and undergo considerable systemic and cellular modifications. However, some patients present a slow recovery of the renal function commonly defined as delayed graft function (DGF). Although clinically well characterized, the molecular mechanisms underlying this condition are not totally defined, thus, we are currently missing specific clinical markers to predict and to make early diagnosis of this event.

Methods

We investigated, using a pathway analysis approach, the transcriptomic profile of peripheral blood mononuclear cells (PBMC) from renal transplant recipients with DGF and with early graft function (EGF), before (T0) and 24 hours (T24) after transplantation.

Results

Bioinformatics/statistical analysis showed that 15 pathways (8 up-regulated and 7 down-regulated) and 11 pathways (5 up-regulated and 6 down-regulated) were able to identify DGF patients at T0 and T24, respectively. Interestingly, the most up-regulated pathway at both time points was NLS-bearing substrate import into nucleus, which includes genes encoding for several subtypes of karyopherins, a group of proteins involved in nucleocytoplasmic transport. Signal transducers and activators of transcription (STAT) utilize karyopherins-alpha (KPNA) for their passage from cytoplasm into the nucleus. In vitro functional analysis demonstrated that in PBMCs of DGF patients, there was a significant KPNA-mediated nuclear translocation of the phosphorylated form of STAT3 (pSTAT3) after short-time stimulation (2 and 5 minutes) with interleukin-6.

Conclusions

Our study suggests the involvement, immediately before transplantation, of karyopherin-mediated nuclear transport in the onset and development of DGF. Additionally, it reveals that karyopherins could be good candidates as potential DGF predictive clinical biomarkers and targets for pharmacological interventions in renal transplantation. However, because of the low number of patients analyzed and some methodological limitations, additional studies are needed to validate and to better address these points.

Renal neutrophil gelatinase-associated lipocalin and kidney injury molecule-1 expression in children with acute kidney injury and Henoch-Schönlein purpura nephritis

The aim of this study was to investigate the expression of neutrophil gelatinase-associated lipocalin (NGAL) and kidney injury molecule-1 (KIM-1) in the serum, urine and renal tissues of children with acute kidney injury (AKI) and Henoch-Schönlein purpura nephritis (A-on-C). A prospective single-center evaluation of the serum, urine and renal NGAL and KIM-1 levels was performed in a cohort of children. Blood and 5-ml urine samples were collected from each patient for the analysis of NGAL and KIM-1 levels using an ELISA. In addition, the expression of NGAL and KIM-1 in the kidney was examined using immunohistochemistry in patients with A-on-C and HSPN. The expression of serum cystatin C, β2-macroglobulin and serum creatinine (SCr), as well as urinary β2-MG and SCr, in the patients with A-on-C was significantly higher than that of HSPN patients, and the expression of NGAL and KIM-1 in the serum and urine in the A-on-C patients was also significantly higher than that of HSPN patients. However, there were no significant differences in the urine protein levels between the two groups. NGAL and KIM-1 were expressed in renal tubular epithelial cells, and the expression of NGAL and KIM-1 in the A-on-C patients was significantly higher than that in HSPN patients. In addition, the urine NGAL and KIM-1 levels were negatively correlated with glomerular filtration rate, but there was no significant correlation between the urine NGAL/KIM-1 and urine protein levels. The changes in serum and urine NGAL and KIM-1 levels may be applied to the diagnosis of A-on-C.

Neutrophil gelatinase-associated lipocalin increases HLA-G(+)/FoxP3(+) T-regulatory cell population in an in vitro model of PBMC

Background

Neutrophil gelatinase-associated lipocalin (NGAL) is emerging as a mediator of various biological and pathological states. However, the specific biological role of this molecule remains unclear, as it serves as a biomarker for many conditions. The high sensitivity of NGAL as a biomarker coupled with relatively low specificity may hide important biological roles. Data point toward an acute compensatory, protective role for NGAL in response to adverse cellular stresses, including inflammatory and oxidative stress. The aim of this study was to understand whether NGAL modulates the T-cell response through regulation of the human leukocyte antigen G (HLA-G) complex, which is a mediator of tolerance.

Methodology/Principal Findings

Peripheral blood mononuclear cells (PBMCs) were obtained from eight healthy donors and isolated by centrifugation on a Ficoll gradient. All donors gave informed consent. PBMCs were treated with four different concentrations of NGAL (40–320 ng/ml) in an iron-loaded or iron-free form. Changes in cell phenotype were analyzed by flow cytometry. NGAL stimulated expression of HLA-G on CD4+ T cells in a dose- and iron-dependent manner. Iron deficiency prevented NGAL-mediated effects, such that HLA-G expression was unaltered. Furthermore, NGAL treatment affected stimulation of regulatory T cells and in vitro expansion of CD4⁺ CD25⁺ FoxP3⁺ cells. An NGAL neutralizing antibody limited HLA-G expression and significantly decreased the percentage of CD4⁺ CD25⁺ FoxP3⁺ cells.

Conclusions/Significance

We provide in vitro evidence that NGAL is involved in cellular immunity. The potential role of NGAL as an immunomodulatory molecule is based on its ability to induce immune tolerance by upregulating HLA-G expression and expansion of T-regulatory cells in healthy donors. Future studies should further evaluate the role of NGAL in immunology and immunomodulation and its possible relationship to immunosuppressive therapy efficacy, tolerance induction in transplant patients, and other immunological disorders.

Plasma NGAL and glomerular filtration rate in cardiac transplant recipients treated with standard or reduced calcineurin inhibitor levels

AIM

Predictors of renal recovery following conversion from calcineurin inhibitor- to proliferation signal inhibitor-based therapy are lacking. We hypothesized that plasma NGAL (P-NGAL) could predict improvement in glomerular filtration rate (GFR) after conversion to everolimus.

PATIENTS & METHODS

P-NGAL was measured in 88 cardiac transplantation patients (median 5 years post-transplant) with renal dysfunction randomized to continuation of conventional calcineurin inhibitor-based immunosuppression or switching to an everolimus-based regimen.

RESULTS

P-NGAL correlated with measured GFR (mGFR) at baseline (R(2) = 0.21; p < 0.001). Randomization to everolimus improved mGFR after 1 year (median [25-75 % percentiles]: ΔmGFR 5.5 [-0.5-11.5] vs -1 [-7-4] ml/min/1.73 m(2); p = 0.006). Baseline P-NGAL predicted mGFR after 1 year (R(2) = 0.18; p < 0.001), but this association disappeared after controlling for baseline mGFR.

CONCLUSION

P-NGAL and GFR correlate with renal dysfunction in long-term heart transplantation recipients. P-NGAL did not predict improvement of renal function after conversion to everolimus-based immunosuppression.

Neutrophil gelatinase-associated lipocalin as a biomarker of acute kidney injury: a critical evaluation of current status

BACKGROUND

The early prediction of acute kidney injury (AKI) by current clinical and laboratory methods remains inadequate. Neutrophil gelatinase-associated lipocalin (NGAL) has emerged as a promising non-invasive biomarker of kidney injury. We systematically reviewed the utility of plasma and urine NGAL measurements for the prediction of AKI in humans.

METHODS

We searched MEDLINE, PubMed and EMBASE for human biomarker studies that included NGAL (January 2005 to October 2013). Studies reporting on the use of NGAL for the early prediction and prognosis of AKI were analysed in three common clinical settings: cardiac surgery, critical illness and kidney transplantation.

RESULTS

We identified 58 manuscripts that met our inclusion and exclusion criteria, reporting on more than 16,500 patients. Following cardiac surgery, NGAL measurement in over 7000 patients was predictive of AKI and its severity, with an overall area under the receiver operator characteristic curve (AUC) of 0.82-0.83. Similar results were obtained in over 8500 critically ill patients. In over 1000 patients undergoing kidney transplantation, NGAL measurements predicted delayed graft function with an overall AUC of 0.87. In all three settings, NGAL significantly improved the prediction of AKI risk over the clinical model alone.

CONCLUSIONS

We identified several studies that collectively strongly support the use of NGAL as a biomarker for the prediction of AKI. However, we noted some limitations, including lack of published studies that adhere to diagnostic study guidelines, heterogeneity in AKI definition, the lack of uniformly applicable cut-off values and variability in the performance of commercially available NGAL assays.

Association of urinary injury biomarkers with mortality and cardiovascular events

Kidney damage is a common sequela of several chronic pathologic conditions. Whether biomarkers of kidney damage are prognostic for more severe outcomes is unknown. We measured three urinary biomarkers (kidney injury molecule-1 [KIM-1], IL-18, and albumin) in 3010 individuals enrolled in the Health, Aging and Body Composition (Health ABC) study and used Cox proportional hazards models to investigate the associations of urinary KIM-1/creatinine (cr), IL-18/cr, and albumin/cr (ACR) with all-cause mortality and cardiovascular disease (CVD). Multivariable models adjusted for demographics, traditional CVD risk factors, and eGFR. Mean age of participants was 74 years, 49% of participants were men, and 41% of participants were black. During the median 12.4 years of follow-up, 1450 deaths and 797 CVD outcomes occurred. Compared with the lowest quartile, successive quartiles had the following adjusted hazard ratios (HRs; 95% confidence intervals [95% CIs]) for mortality: KIM-1/cr: (1.21; 1.03 to 1.41), (1.13; 0.96 to 1.34), and (1.28; 1.08 to 1.52); IL-18/cr: (1.02; 0.88 to 1.19), (1.16; 0.99 to 1.35), and (1.06; 0.90 to 1.25); ACR: (1.08; 0.91 to 1.27), (1.24; 1.06 to 1.46), and (1.63; 1.39 to 1.91). In similar analyses, only ACR quartiles associated with CVD: (1.19; 0.95 to 1.48), (1.35; 1.08 to 1.67), and (1.54; 1.24 to 1.91). Urinary KIM-1 had a modest association with all-cause mortality but did not associate with CVD, and urinary IL-18 did not associate with either outcome. In contrast, albuminuria strongly associated with all-cause mortality and CVD. Future studies should evaluate reasons for these differences in the prognostic importance of individual kidney injury markers.

Neutrophil gelatinase associated lipocalin in acute kidney injury

BACKGROUND

Neutrophil gelatinase-associated lipocalin (NGAL) is a member of the lipocalin family of proteins. Usually, NGAL is produced and secreted by kidney tubule cells at low levels, but the amount produced and secreted into the urine and serum increases dramatically after ischemic, septic, or nephrotoxic injury of the kidneys. The purpose of our review article is to summarize the role of NGAL in acute kidney injury (AKI), emergent, and intensive care.

METHODS

A PubMed search was performed (only English-language articles concerning human subjects were considered) using each of the following search term combinations: neutrophil gelatinase-associated lipocalin OR NGAL and acute kidney injury OR AKI; cardiac surgery; heart failure OR cardiology; intensive care; emergency department OR emergency medicine; nephropathy OR nephrotoxicity and transplantation.

RESULTS

The results of our search yielded 339 articles. Of the 339 articles, 160 were eligible for review based on the predefined criteria for inclusion.

CONCLUSION

Based on the evidence reviewed, it is clear that patient NGAL level is an appropriate, sensitive, and specific early biomarker of AKI caused by a variety of different etiologies. It is advised that a multidisciplinary group of experts come together to make recommendations and propose a consensus of clinical procedures to advance the most efficacious NGAL monitoring protocol for early detection and treatment of patients with AKI.

Predicting 5-year risk of kidney transplant failure: a prediction instrument using data available at 1 year posttransplantation

BACKGROUND

Accurate prediction of kidney transplant failure remains imperfect. The objective of this study was to develop and validate risk scores predicting 5-year transplant failure, based on data available 12 months posttransplantation.

STUDY DESIGN

Development and then independent multicenter validation of risk scores predicting death-censored and overall transplant failure.

SETTING & PARTICIPANTS

Outcomes of kidney transplant recipients (n=651) alive with transplant function 12 months posttransplantation in Birmingham, United Kingdom, were used to develop models predicting transplant failure risk 5 years posttransplantation. The resulting risk scores were evaluated for prognostic utility (discrimination, calibration, and risk reclassification) in independent cohorts from Tours, France (n=736); Leeds, United Kingdom (n=787); and Halifax, Canada (n=475).

PREDICTORS

Weighted regression coefficients for baseline and 12-month demographic and clinical predictor characteristics.

OUTCOMES

Death-censored and overall transplant failure 5 years posttransplantation.

MEASUREMENTS

Baseline data and time to transplant failure.

RESULTS

Following model development, variables included in separate scores for death-censored and overall transplant failure included recipient age, sex, and race; acute rejection; transplant function; serum albumin level; and proteinuria. In the validation cohorts, these scores showed good to excellent discrimination for death-censored transplant failure (C statistics, 0.78-0.90) and moderate to good discrimination for overall transplant failure (C statistics, 0.75-0.81). Both scores demonstrated good calibration (Hosmer-Lemeshow P>0.05 in all cohorts). Compared with estimated glomerular filtration rate in isolation, application of the scores resulted in statistically significant and clinically relevant risk reclassification for death-censored transplant failure (net reclassification improvement [NRI], 36.1%-83.0%; all P<0.001) and overall transplant failure (NRI, 38.7%-53.5%; all P<0.001). Compared with the previously described US Renal Data System-based risk calculator, significant and relevant risk reclassification for overall transplant failure was seen (NRI, 30.0%; P<0.001).

LIMITATIONS

Validation is required in further populations.

CONCLUSIONS

These validated risk scores may be of prognostic utility in kidney transplantation, accurately identifying at-risk transplants, and informing clinicians and patients.

Urinary neutrophil gelatinase-associated lipocalin after kidney transplantation: is it a good biomarker to assess delayed graft function?

Delayed graft function (DGF) is a common complication after transplantation. Its incidence is increased among patients receiving a graft from an expanded-criteria donor. Urinary neutrophil gelatinase-associated lipocalin (uNGAL), an acute kidney injury marker, could in the first days after transplantation be an early marker of DGF. We collected urine samples from 38 renal transplant recipients on days 1, 3, 6, and 10 post-transplantation, and months 1 and 6 creatinine to determine uNGAL, serum creatinine, Cystatin C, and albumin/creatinine ratio. We divided the patients into 2 groups, based on whether they developed DGF. We observed that mean uNGAL concentrations, Cystatin C, serum creatinine, and albumin/creatinine ratio were significantly lower in the non-DGF cohort on all measured days. uNGAL at day 3 showed a positive correlation with serum creatinine at day 10 (R = 0.58; P < .00) and day 30 (R = 0.57; P = .016) as well as with the length of hospital stay (r = 0.47; P < .00). Receiver operating characteristic analyses performed to assess the potential of uNGAL to predict DGF showed an area under the curve for day 3 of uNGAL of 0.917 (confidence interval [CI], 0.79-1.00; P = .00), with an optimal cutoff level of 124 ng/mL, sensitivity of 80% (CI, 62%-97%), and specificity of 83% (62%-104%; P = .001). In the first days after transplantation, uNGAL could be an early marker of DGF, providing additional information to standard biomarkers and potentially helping clinicians to take early measures to mitigate DGF.

C-terminal agrin fragment--a new fast biomarker for kidney function in renal transplant recipients

BACKGROUND

The C-terminal agrin fragment (CAF) is a cleavage product of agrin, the major proteoglycan of the glomerular basement membrane. This article studies if CAF could serve as a biomarker for renal function in renal transplant recipients.

MATERIAL AND METHODS

We measured serum CAF and creatinine concentrations and calculated estimated glomerular filtration rate (eGFR) (MDRD) in 96 healthy individuals and in 110 end-stage renal disease patients undergoing kidney transplantation before and after transplantation. Correlation between CAF and creatinine concentrations/eGFR was calculated as within-patient (cWP) and between-patient correlations (cBP). Moreover, we evaluated the association of CAF with delayed graft function (DGF). The diagnostic value of CAF for early detection of DGF compared to creatinine was evaluated by receiver operating characteristics (ROC) analysis.

RESULTS

CAF concentrations strongly correlated with creatinine (r = 0.86 (cWP), r = 0.74 (cBP)) and eGFR (MDRD) (r = 0.86 (cWP), r = 0.77 (cBP)). Pre-transplant (pre-Tx) CAF concentrations were 19-fold higher than in healthy individuals (1,115.0 (258.4-3,990.0) vs. 56.6 (20.0-109.5) pM). After transplantation, CAF decreased significantly faster than creatinine (postoperative days 1-3 (POD 1-3): 562.8 (101.6-2,113.0) pM; creatinine: pre-Tx 6.9 (3.1-15.7), POD 1-3: 6.4 (1.7-12.7) mg/dl, p < 0.001). Stable concentrations were reached 1-3 months after transplantation for CAF and creatinine (CAF 145.1 (6.7-851.0) pM; creatinine 1.6 (0.7-8.0) mg/dl). CAF concentrations at POD 1-3 were significantly associated with DGF and outperformed creatinine in early detection of DGF (area under the curve (AUC) CAF 80.7% (95% CI 72.3-89.1%) vs. AUC creatinine 71.3% (95% CI 61.8-81.1%), p = 0.061).

CONCLUSION

CAF is a promising new and fast biomarker for kidney function and may serve as a new tool for the early detection of DGF.

Urinary neutrophil gelatinase-associated lipocalin predicts graft loss after acute kidney injury in kidney transplant

OBJECTIVE

Establish the prognostic value for graft loss of urinary neutrophil gelatinase-associated lipocalin (uNGAL), kidney injury molecule-1 (uKIM-1), interleukin-18 (uIL-18), and heat shock protein 72 (uHsp72) in kidney transplant recipients (KTR) with acute kidney injury (AKI).

METHODS

Biomarkers were measured in 67 KTR with AKI caused by different entities.

RESULTS

After 1 year, 11 KTR with graft loss had higher uNGAL compared to KTR without loss (p < 0.001). There were no differences for uKIM-1, uIL-18 and uHsp-72. uNGAL >200 ng/mL had 84% sensitivity and 86% specificity for graft loss (ROC AUC: 0.89, 95% CI: 0.81-0.97). uNGAL may be useful to predict graft loss after AKI.

Urinary Neutrophil Gelatinase-Associated Lipocalin predicts the severity of contrast-induced acute kidney injury in chronic kidney disease patients undergoing elective coronary procedures

Background

Contrast-induced acute kidney injury (CI-AKI) particularly in high risk patients with chronic kidney disease (CKD), increases morbidity and mortality. Neutrophil gelatinase-associated lipocalin (NGAL) is a protein excreted by the kidney during AKI. There are no urine (u) NGAL data as an early CI-AKI marker in CKD patients undergoing coronary procedures.

Methods

This prospective study enrolled 130 patients with estimated glomerular filtration rate (eGFR) < 60 ml/min/1.73 m² undergoing elective coronary procedures. Serial urine samples, obtained at baseline and 3, 6, 12, 18, and 24 h post contrast administration were analyzed by NGAL ELISA kit. AKI was defined as an increase in serum creatinine (SCr) of ≥ 0.3 mg/dl or ≥ 1.5 times baseline SCr within 48 h per 2012 KDIGO guidelines. Receiver operator characteristic curve analyses identified optimal uNGAL and delta of uNGAL values for diagnosing CI-AKI.

Results

The uNGAL was significantly and inverse correlated with eGFR (R = 0.25, P < 0.005). CI-AKI developed in 16/130 (12.31%) patients: 13 and 3 in CI-AKI stages I and II, respectively. uNGAL and delta of uNGAL were significantly higher in the CI-AKI group when compared with the No CI-AKI group (P < 0.05). The best uNGAL cut-off for optimal sensitivity 94%, specificity 78%, and area under the curve 0.84 for predicting CI-AKI was 117 ng/mL at 6 h, respectively. Corresponding values for predicting CI-AKI stage II were 100%, 87% and 0.9 when using an uNGAL of 264 ng/mL at 6 h.

Conclusions

Monitoring of uNGAL levels not only provide the early detecting CI-AKI but also predict the severity of CI-AKI in CKD patients undergoing elective coronary procedures.

Neutrophil gelatinase-associated lipocalin in kidney transplantation is an early marker of graft dysfunction and is associated with one-year renal function

Urinary neutrophil gelatinase-associated lipocalin (uNGAL) has been suggested as potential early marker of delayed graft function (DGF) following kidney transplantation (KTx). We conducted a prospective study in 40 consecutive KTx recipients to evaluate serial changes of uNGAL within the first week after KTx and assess its performance in predicting DGF (dialysis requirement during initial posttransplant week) and graft function throughout first year. Urine samples were collected on post-KTx days 0, 1, 2, 4, and 7. Linear mixed and multivariable regression models, receiver-operating characteristic (ROC), and areas under ROC curves were used. At all-time points, mean uNGAL levels were significantly higher in patients developing DGF (n = 18). Shortly after KTx (3–6 h), uNGAL values were higher in DGF recipients (on average +242 ng/mL, considering mean dialysis time of 4.1 years) and rose further in following days, contrasting with prompt function recipients. Day-1 uNGAL levels accurately predicted DGF (AUC-ROC = 0.93), with a performance higher than serum creatinine (AUC-ROC = 0.76), and similar to cystatin C (AUC-ROC = 0.95). Multivariable analyses revealed that uNGAL levels at days 4 and 7 were strongly associated with one-year serum creatinine. Urinary NGAL is an early marker of graft injury and is independently associated with dialysis requirement within one week after KTx and one-year graft function.

Effect of pro-inflammatory cytokine (IFN-γ +874, IL-18-137 G/C,-607 C/A) genes in relation to risk of vesico-ureteral reflux

AIM

The aim this work is to estimate whether genetic polymorphisms of +874 of IFN-γ and -137 G/C,-607 C/A of IL-18 genes are implicated in the development of VUR, because a vast literature indicates that genetic variations play a significant role in the pathogenesis of VUR.

MATERIALS AND METHODS

The PCR single specific primer (SSP) and amplification refractory mutation system (ARMS) were applied for analyzing the polymorphic sites of -137 G/C,-607 C/A of IL-18 and +874 of IFN-γ genes in 110 healthy controls and 124 VUR children.

RESULTS

A significant relationship was found between AT and combined AT + TT genotypes of IFN-γ and highly increased risk of VUR (OR = 4.2, 95% CI, 2.00-9.24; p < 0.0001: OR = 4.00, 95% CI, 1.90-8.70, p < 0.0001, respectively). On the other hand, the genotype frequency of IL18-137 G/C indicated a significant assessment of the decrease risk of VUR for GC and GC + CC genotypes (OR = 0.53, 95% CI, 0.3-0.9; p = 0.02: OR = 0.53, 95% CI, 0.3-0.92 p = 0.01, respectively). No significant association was found between -607 C/A polymorphism of IL-18 and UVR.

CONCLUSION

To the author's best knowledge, this is the first data regarding polymorphism of IFN-γ (+874) cytokine genes that highly increased the risk of VUR. To confirm the presented data, further studies should be done in different populations with a larger sample size.

Role of renal biomarkers as predictors of acute kidney injury in cardiac surgery

Cardiac surgery is unique in using cardiopulmonary bypass in various clinical scenarios. Injury of vital organs is unavoidable in the perioperative period. Acute kidney injury is a consequence of the systemic inflammatory response after bypass, emboli, ischemia, and low cardiac output states, reportedly occurring in 30%–40% of open heart surgeries. Acute kidney injury is associated with increased morbidity, mortality, and cost. Many preventive measures (off-pump procedures, decreased crossclamp time, pulsatile flow, adequate hydration) are taken in the perioperative period to avoid organ injury, but in vain. Traditionally, blood urea, serum creatinine, and creatinine clearance rate were applied for prediction of acute kidney injury. The recent emergence of biomarkers such as neutrophil gelatinase-associated lipocalin, cystatin C, liver-type fatty acid binding protein, interleukin-18, kidney injury molecule-1, and tetrahydrobiopterin have helped in detecting acute kidney injury long before the rise of serum creatinine. These biomarkers can also be used as tools for predicting therapeutic effects in acute kidney injury and for monitoring drug toxicity. This review consolidates the knowledge of biomarkers and their application in acute kidney injury management.

Repulsive guidance cue semaphorin 3A in urine predicts the progression of acute kidney injury in adult patients from a mixed intensive care unit

BACKGROUNDS

Predicting the development of acute kidney injury (AKI) in the critical care setting is challenging. Although several biomarkers showed somewhat satisfactory performance for detecting established AKI even in a heterogeneous disease-oriented population, identification of new biomarkers that predict the development of AKI accurately is urgently required.

METHODS

A single-center prospective observational cohort study was undertaken to evaluate for the first time the reliability of the newly identified biomarker semaphorin 3A for AKI diagnosis in heterogeneous intensive care unit populations. In addition to five urinary biomarkers of L-type fatty acid-binding protein (L-FABP), neutrophil gelatinase-associated lipocalin (NGAL), IL-18, albumin and N-acetyl-β-d-glucosaminidase (NAG), urinary semaphorin 3A was measured at intensive care unit (ICU) admission.

RESULTS AND CONCLUSION

Three hundred thirty-nine critically ill adult patients were recruited for this study. Among them, 131 patients (39%) were diagnosed with AKI by the RIFLE criteria and 66 patients were diagnosed as AKI at post-ICU admission (later-onset AKI). Eighty-four AKI patients showed worsening severity during 1 week observation (AKI progression). Although L-FABP, NGAL and IL-18 showed significantly higher area under the curve (AUC)-receiver operating characteristic (ROC) values than semaphorin 3A in detecting established AKI, semaphorin 3A was able to detect later-onset AKI and AKI progression with similar AUC-ROC values compared with the other five biomarkers [AUC-ROC (95% CI) for established AKI 0.64 (0.56-0.71), later-onset AKI 0.71 (0.64-0.78), AKI progression 0.71 (0.64-0.77)]. Urinary semaphorin 3A was not increased in non-progressive established AKI, while the other biomarkers were elevated regardless of further progression. Finally, sepsis did not have any impact on semaphorin 3A while the other urinary biomarkers were increased with sepsis. Semaphorin 3A is a new biomarker of AKI which may have a distinct predictive use for AKI progression when compared with other AKI biomarkers.

Urine proteomics in kidney transplantation

The transplanted kidney, through its urinary output, provides a medium through which the molecular constitution can provide insight into either the healthy function or developing dysfunction of a newly transplanted organ. An assay that would detect the aberration of early biomarkers of allograft injury using only urine samples from patients would provide many advantages over the current use of creatinine and tissue biopsies, as these means are either relatively non-specific or very invasive. Several urine biomarkers have been correlated with allograft injury, including CXCL9, CXCL10, CCL2, NGAL, IL-18, cystatin C, KIM-1 and Tim-3. The recent results of the CTOT-01 trial serve to validate the predictive value of the CXCL9 biomarker as a non-invasive biomarker for rejection and a prognostic indicator of graft function. There is now a preponderance of evidence showing a value of urinary monitoring of CXCL9 and CXCL10 with respect to detection of acute kidney allograft rejection. The value of the assay has been validated as a means of reducing the need for kidney transplant biopsy and applying biopsy in a more targeted manner. Additional goals for non-invasive monitoring would include predictive value prior to creatinine elevation that in turn would permit earlier, preemptive treatment of rejection.

Does HIV infection promote early kidney injury in women?

BACKGROUND

In HIV-infected women, urine concentrations of novel tubulointerstitial injury markers, interleukin-18 (IL-18) and kidney injury marker-1 (KIM-1), are associated with kidney function decline and all-cause mortality. We hypothesized that HIV-infected individuals with preserved kidney filtration function would have more extensive kidney injury, as determined by urine injury markers, compared to the uninfected controls, and that risk factors for tubulointerstitial injury would differ from risk factors for albuminuria.

METHODS

In this cross-sectional study, we compared urine concentrations of IL-18, KIM-1 and albumin-to-creatinine ratio (ACR) in 908 HIV-infected and 289 HIV-uninfected women enrolled in the Women's Interagency HIV Study, utilizing stored urine specimens from visits between 1999 and 2000.

RESULTS

After multivariate-adjusted linear regression analysis, mean urine concentrations were higher in HIV-infected individuals by 38% for IL-18 (P<0.0001), 12% for KIM-1 (P=0.081) and 47% for ACR (P<0.0001). Higher HIV RNA level (15% per 10-fold increase; P<0.0001), lower CD4(+) lymphocyte count (8% per doubling; P=0.0025), HCV infection (30%; P=0.00018) and lower high-density lipoprotein (5% per 10 mg/dl; P=0.0024) were each associated with higher IL-18 concentrations. In contrast, hypertension (81%; P<0.0001) and diabetes (47%; P=0.018) were among the strongest predictors of higher ACR, though HIV RNA level (15% per 10-fold increase; P=0.0004) was also associated with higher ACR.

CONCLUSIONS

HIV-infected women had more extensive tubulointerstitial and glomerular injury than uninfected women, but the associated factors differed among the urine biomarkers. Combinations of urinary biomarkers should be investigated to further characterize early kidney injury in HIV-infected women.

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

INTRODUCTION

Neutrophil gelatinase-associated lipocalin (NGAL) is a powerful biomarker for the early detection of acute kidney injury. However, recent data suggest that NGAL also plays an important role in chronic kidney disease (CKD), reflecting the level of acute kidney damage within the CKD condition. To study whether elevated NGAL levels in CKD are a consequence of damaged tubular cells or rather due to extrarenal production, we investigated NGAL levels in anephric patients on dialysis.

METHODS

Plasma NGAL levels were investigated in 14 dialysis patients who underwent bilateral nephrectomy (anephric group), 18 anuric dialysis patients with remaining kidneys (dialysis group) and 12 healthy patients (healthy group).

RESULTS

Plasma NGAL levels were significantly lower in the healthy group compared with the anephric group (143 vs. 981 ng/mL; P < 0·001) or the dialysis group (143 vs. 838 ng/mL; P < 0·001), respectively. However, NGAL levels did not differ between the anephric group and the dialysis group (981 vs. 838 ng/mL; P = 0·19).

DISCUSSION

Assuming that NGAL is highly expressed in chronically damaged kidneys due to tubular stress, there should be significantly less NGAL in anephric patients compared with anuric dialysis patients with remaining kidneys. In contrast to this hypothesis, we found no difference in NGAL expression between these two groups, proving the entire extrarenal NGAL production in anephric patients and suggesting that the tubular NGAL expression seems to be negligible in anuric dialysis patients.

Acute kidney injury and critical cardiac disease

The field of cardiac intensive care continues to advance in tandem with congenital heart surgery. The survival of patients with critical congenital heart disease is seldom in question. Consequently, the focus has now shifted to that of morbidity reduction and eventual elimination. Acute kidney injury (AKI) after cardiac surgery is associated with adverse outcomes, including prolonged intensive care and hospital stays, diminished quality of life, and increased long-term mortality. Acute kidney injury occurs frequently, complicating 30% to 40% of adult and pediatric cardiac surgeries. Patients who require dialysis are at high risk of mortality, but even minor degrees of postoperative AKI portend a significant increase in mortality and morbidity.

Does living donor hyperoxia have an impact on kidney graft function after transplantation?

Background

Improvement in the outcome of organ transplantation is related to advances in patient selection criteria, organ preservation, operative techniques, perioperative care and efficacy of immunosuppressive agents.

Objectives

We aimed to evaluate the effects of higher levels of arterial PaO₂ in donors on DGF (delayed graft function).

Patients and Methods

Forty patients over 18 years old with stage 4-5 chronic kidney disease (CKD) who received a kidney from living donors were enrolled. They were randomly grouped in to the case (n = 17) and control (n = 23) groups and were followed for 2 weeks after transplantation. Donors were exposed to 60% oxygen for at least 2 hours with a face-mask (venture mask) for 2 consecutive days before transplantation until arterial oxygen pressure increased in arterial blood gas to 200 mmHg. Neutrophil gelatinase associated lipocalin (NGAL), Interleuk-18 (IL-18), tumor necrosis factor- α (TNF-α) and transforming growth factor–β (TGF-β) could be good biomarkers for early diagnosis of kidney injury in renal transplant recipients; we assessed kidney function with these biomarkers.

Results

Forty living kidney transplantations including 17 cases and 23 controls were performed; female gender was more prevalent in recipients (n = 16, 40%). The mean age of recipients was 36.1 ± 12.4 (18-67) years old. DGF was detected in 2 (5.95%) individuals, from whom one was in the case group and the other one in the control group. In the univariate analysis, there was no significant correlation between age and biomarkers in urine and serum unless for the second serum NGAL (P = 0.02, r = -0.06) and second urine IL 18 (P = 0.03, r = -0.5) which had a negative correlation, and first urine TNF α (P = 0.02, r = 0.7) which had a positive correlation.

Conclusions

Oxygen therapy in the case group had no significant impact on protection from DGF.

Serum aminoacylase-1 is a novel biomarker with potential prognostic utility for long-term outcome in patients with delayed graft function following renal transplantation

Early identification and prognostic stratification of delayed graft function following renal transplantation has significant potential to improve outcome. Mass spectrometry analysis of serum samples, before and on day 2 post transplant from five patients with delayed graft function and five with an uncomplicated transplant, identified aminoacylase-1 (ACY-1) as a potential outcome biomarker. Following assay development, analysis of longitudinal samples from an initial validation cohort of 55 patients confirmed that the ACY-1 level on day 1 or 2 was a moderate predictor of delayed graft function, similar to serum creatinine, complementing the strongest predictor cystatin C. A further validation cohort of 194 patients confirmed this association with area under ROC curves (95% CI) for day 1 serum (138 patients) of 0.74 (0.67-0.85) for ACY-1, 0.9 (0.84-0.95) for cystatin C, and 0.93 (0.88-0.97) for both combined. Significant differences in serum ACY-1 levels were apparent between delayed, slow, and immediate graft function. Analysis of long-term follow-up for 54 patients with delayed graft function showed a highly significant association between day 1 or 3 serum ACY-1 and dialysis-free survival, mainly associated with the donor-brain-dead transplant type. Thus, proteomic analysis provides novel insights into the potential clinical utility of serum ACY-1 levels immediately post transplantation, enabling subdivision of patients with delayed graft function in terms of long-term outcome. Our study requires independent confirmation.