Cytomegalovirus Genetic Diversity Following Primary Infection

BACKGROUND

Infection with multiple cytomegalovirus (CMV) strains (mixed infection) was reported in a variety of hosts. As the virus genetic diversity in primary CMV infection and the changes over time remain incompletely defined, we examined CMV diversity and changes in diversity over time in healthy adolescent females who participated in a phase 2 CMV gB/MF59 vaccine trial.

METHODS

CMV genetic diversity was determined by genotyping of 5 genes-gB (UL55), gH (UL75), gN (UL73), US28, and UL144-in urine, saliva, and plasma samples from 15 study subjects.

RESULTS

At the time of primary infection, 5 of 12 (42%) urine samples had multiple virus strains, and 50% of vaccine recipients were infected with gB1 genotype (vaccine strain). Mixed infection was documented in all 15 subjects within 3 months after primary infection, and the majority had different CMV genotypes in different compartments. Changes in genotypes over time were observed in all subjects.

CONCLUSIONS

Infection with multiple CMV genotypes was common during primary infection and further diversification occurred over time. Infection with gB1 genotype in vaccine recipients suggests a lack of strain-specific protection from the vaccine. As only 5 polymorphic genes were assessed, this study likely underestimated the true genetic diversity in primary CMV infection.

Pre-transplant Evaluation of Donor Urinary Biomarkers can Predict Reduced Graft Function After Deceased Donor Kidney Transplantation

Several recipient biomarkers are reported to predict graft dysfunction, but these are not useful in decision making for the acceptance or allocation of deceased donor kidneys; thus, it is necessary to develop donor biomarkers predictive of graft dysfunction. To address this issue, we prospectively enrolled 94 deceased donors and their 109 recipients who underwent transplantation between 2010 and 2013 at 4 Korean transplantation centers. We investigated the predictive values of donor urinary neutrophil gelatinase-associated lipocalin (NGAL), kidney injury molecule-1 (KIM-1), and L-type fatty acid binding protein (L-FABP) for reduced graft function (RGF). We also developed a prediction model of RGF using these donor biomarkers. RGF was defined as delayed or slow graft function. Multiple logistic regression analysis was used to generate a prediction model, which was internally validated using a bootstrapping method. Multiple linear regression analysis was used to assess the association of biomarkers with 1-year graft function. Notably, donor urinary NGAL levels were associated with donor AKI (P = 0.014), and donor urinary NGAL and L-FABP were predictive for RGF, with area under the receiver-operating characteristic curves (AUROC) of 0.758 and 0.704 for NGAL and L-FABP, respectively. The best-fit model including donor urinary NGAL, L-FABP, and serum creatinine conveyed a better predictive value for RGF than donor serum creatinine alone (P = 0.02). In addition, we generated a scoring method to predict RGF based on donor urinary NGAL, L-FABP, and serum creatinine levels. Diagnostic performance of the RGF prediction score (AUROC 0.808) was significantly better than that of the DGF calculator (AUROC 0.627) and the kidney donor profile index (AUROC 0.606). Donor urinary L-FABP levels were also predictive of 1-year graft function (P = 0.005). Collectively, these findings suggest donor urinary NGAL and L-FABP to be useful biomarkers for RGF, and support the use of a new scoring system based on donor biomarkers to facilitate decision-making in acceptance and allocation of deceased donor kidneys and contribute to maximal organ utilization.

Urinary Vitamin D Binding Protein and KIM-1 Are Potent New Biomarkers of Major Adverse Renal Events in Patients Undergoing Coronary Angiography

Background

Vitamin-D-binding protein (VDBP) is a low molecular weight protein that is filtered through the glomerulus as a 25-(OH) vitamin D 3/VDBP complex. In the normal kidney VDBP is reabsorbed and catabolized by proximal tubule epithelial cells reducing the urinary excretion to trace amounts. Acute tubular injury is expected to result in urinary VDBP loss. The purpose of our study was to explore the potential role of urinary VDBP as a biomarker of an acute renal damage.

Method

We included 314 patients with diabetes mellitus or mild renal impairment undergoing coronary angiography and collected blood and urine before and 24 hours after the CM application. Patients were followed for 90 days for the composite endpoint major adverse renal events (MARE: need for dialysis, doubling of serum creatinine after 90 days, unplanned emergency rehospitalization or death).

Results

Increased urine VDBP concentration 24 hours after contrast media exposure was predictive for dialysis need (no dialysis: 113.06 ± 299.61ng/ml, n = 303; need for dialysis: 613.07 ± 700.45 ng/ml, n = 11, Mean ± SD, p<0.001), death (no death during follow-up: 121.41 ± 324.45 ng/ml, n = 306; death during follow-up: 522.01 ± 521.86 ng/ml, n = 8; Mean ± SD, p<0.003) and MARE (no MARE: 112.08 ± 302.00ng/ml, n = 298; MARE: 506.16 ± 624.61 ng/ml, n = 16, Mean ± SD, p<0.001) during the follow-up of 90 days after contrast media exposure. Correction of urine VDBP concentrations for creatinine excretion confirmed its predictive value and was consistent with increased levels of urinary Kidney Injury Molecule-1 (KIM-1) and baseline plasma creatinine in patients with above mentioned complications. The impact of urinary VDBP and KIM-1 on MARE was independent of known CIN risk factors such as anemia, preexisting renal failure, preexisting heart failure, and diabetes.

Conclusions

Urinary VDBP is a promising novel biomarker of major contrast induced nephropathy-associated events 90 days after contrast media exposure.

[Diagnostic values of urinary netrin-1 and kidney injury molecule-1 for acute kidney injury induced by neonatal asphyxia]

OBJECTIVE

To investigate the values of urinary netrin-1 and kidney injury molecule-1 (KIM-1) in the early diagnosis of acute kidney injury (AKI) induced by neonatal asphyxia.

METHODS

A total of 80 full-term neonates with asphyxia were enrolled (mild asphyxia: 34 neonates; severe asphyxia: 46 neonates). Forty normal full-term neonates were selected as the control group. Urinary samples were collected from the neonates in the three groups within 12 hours and 13-48 hours after birth. ELISA was applied to measure urinary levels of netrin-1 and KIM-1. Peripheral venous blood samples were also collected to measure serum creatinine (Scr) level.

RESULTS

Compared with the control group, the asphyxia group had significantly higher urinary levels of netrin-1 and KIM-1 within 48 hours after birth and a significantly higher Scr level within 13-48 hours after birth (P<0.05). The neonates in the AKI group had significantly higher urinary levels of netrin-1 and KIM-1 and Scr level within 48 hours after birth than those in the non-AKI group (P<0.05). The areas under the receiver operating characteristic curve for urinary netrin-1 and KIM-1 levels within 12 hours after birth to predict AKI after asphyxia were 0.878 (95% CI: 0.775-0.981; P<0.01) and 0.899 (95% CI: 0.829-0.969; P<0.01), respectively. Any two indicators of urinary netrin-1 level, urinary KIM-1 level, and Scr level within 12 hours after neonatal asphyxia had a positive correlation (P<0.05).

CONCLUSIONS

Urinary netrin-1 and KIM-1 levels increase significantly when neonates with asphyxia develop AKI. Urinary netrin-1 and KIM-1 can be used as indicators for the early diagnosis of AKI after asphyxia.

[Diagnostic values of urinary netrin-1 and kidney injury molecule-1 for acute kidney injury induced by neonatal asphyxia]

OBJECTIVE

To investigate the values of urinary netrin-1 and kidney injury molecule-1 (KIM-1) in the early diagnosis of acute kidney injury (AKI) induced by neonatal asphyxia.

METHODS

A total of 80 full-term neonates with asphyxia were enrolled (mild asphyxia: 34 neonates; severe asphyxia: 46 neonates). Forty normal full-term neonates were selected as the control group. Urinary samples were collected from the neonates in the three groups within 12 hours and 13-48 hours after birth. ELISA was applied to measure urinary levels of netrin-1 and KIM-1. Peripheral venous blood samples were also collected to measure serum creatinine (Scr) level.

RESULTS

Compared with the control group, the asphyxia group had significantly higher urinary levels of netrin-1 and KIM-1 within 48 hours after birth and a significantly higher Scr level within 13-48 hours after birth (P<0.05). The neonates in the AKI group had significantly higher urinary levels of netrin-1 and KIM-1 and Scr level within 48 hours after birth than those in the non-AKI group (P<0.05). The areas under the receiver operating characteristic curve for urinary netrin-1 and KIM-1 levels within 12 hours after birth to predict AKI after asphyxia were 0.878 (95% CI: 0.775-0.981; P<0.01) and 0.899 (95% CI: 0.829-0.969; P<0.01), respectively. Any two indicators of urinary netrin-1 level, urinary KIM-1 level, and Scr level within 12 hours after neonatal asphyxia had a positive correlation (P<0.05).

CONCLUSIONS

Urinary netrin-1 and KIM-1 levels increase significantly when neonates with asphyxia develop AKI. Urinary netrin-1 and KIM-1 can be used as indicators for the early diagnosis of AKI after asphyxia.

Urinary Kidney Injury Molecules in Children with Iron-Deficiency Anemia

BACKGROUND

The aim of this study was to investigate the urine levels of human kidney injury molecule-1 (KIM-1), neutrophil gelatinase-associated lipocalin (NGAL), N-acetyl-β-D-glucosaminidase (NAG), and liver-type fatty acid-binding protein (L-FABP) in children with iron-deficiency anemia (IDA).

MATERIAL AND METHODS

Thirty-five children with IDA and 32 matched healthy controls were recruited. We assessed complete blood count, serum iron, iron-binding capacity, ferritin, serum levels of urea, creatinine (Cr), sodium (Na), potassium (K), calcium (Ca), and glucose levels. Estimated glomerular filtration rate (eGFR) was calculated. Urinary NAG, NGAL, KIM-1, and L-FABP were measured and divided by urine creatinine for comparisons.

RESULTS

There were no significant differences in serum urea, Cr, or eGFR between the IDA group and the control group (p>0.05, for all). IDA patients had significantly higher urine NGAL/Cr, L-FABP/Cr, KIM-1/Cr, and NAG/Cr compared with the control group (p<0.05). There were significant negative correlations between hemoglobin, hematocrit, red blood cell count, and urine NGAL/Cr, NAG/Cr, L-FABP/Cr, KIM-1/Cr levels (p<0.05).

CONCLUSIONS

Higher urinary kidney injury molecule levels in IDA patients suggest a possible subclinical renal injury in pediatric IDA patients whose renal functions and serum electrolytes were normal.

Associations between Urinary Excretion of Cadmium and Renal Biomarkers in Nonsmoking Females: A Cross-Sectional Study in Rural Areas of South China

OBJECTIVES

The aim of this study was to systematically evaluate the relationship between urinary excretion of cadmium (U-Cd) and biomarkers of renal dysfunction.

METHODS

One hundred eighty five non-smoking female farmers (aged from 44 to 71 years) were recruited from two rural areas with different cadmium levels of exposure in southern China. Morning spot urine samples were collected for detecting U-Cd, urinary creatinine (U-cre), β₂-microglobulin (β₂-MG), α₁-microglobulin (α₁-MG), metallothionein (MT), retinol binding protein (RBP), albumin (AB), N-acetyl-β-D-glucosaminidase (NAG), alkaline phosphatase (ALP), γ-glutamyl transpeptidase (GGT) and kidney injury molecule-1 (KIM-1). Spearman's rank correlation was carried out to assess pairwise bivariate associations between continuous variables. Three different models of multiple linear regression (the cre-corrected, un-corrected and cre-adjusted model) were used to model the dose-response relationships between U-Cd and nine urine markers.

RESULTS

Spearman's rank correlation showed that NAG, ALP, RBP, β₂-MG and MT were significantly associated with U-Cd for both cre-corrected and observed data. Generally, NAG correlated best with U-Cd among the nine biomarkers studied, followed by ALP and MT. In the un-corrected model and cre-adjusted model, the regression coefficients and R² of nine biomarkers were larger than the corresponding values in the cre-corrected model, indicating that the use of observed data was better for investigating the relationship between biomarkers and U-Cd than cre-corrected data.

CONCLUSIONS

Our results suggest that NAG, MT and ALP in urine were better biomarkers for long-term environmental cadmium exposure assessment among the nine biomarkers studied. Further, data without normalization with creatinine show better relationships between cadmium exposure and renal dysfunction.

Nanoparticle Detection of Urinary Markers for Point-of-Care Diagnosis of Kidney Injury

The high incidence of acute and chronic kidney injury due to various environmental factors such as heavy metals or chemicals has been a major problem in developing countries. However, the diagnosis of kidney injury in these areas can be more challenging due to the lack of highly sensitive and specific techniques that can be applied in point-of-care settings. To address this, we have developed a technique called ‘micro-urine nanoparticle detection (μUNPD)’, that allows the detection of trace amounts of molecular markers in urine. Specifically, this technique utilizes an automated on-chip assay followed by detection with a hand-held device for the read-out. Using the μUNPD technology, the kidney injury markers KIM-1 and Cystatin C were detected down to concentrations of 0.1 ng/ml and 20 ng/ml respectively, which meets the cut-off range required to identify patients with acute or chronic kidney injury. Thus, we show that the μUNPD technology enables point of care and non-invasive detection of kidney injury, and has potential for applications in diagnosing kidney injury with high sensitivity in resource-limited settings.

Subclinical kidney injury before and 1 year after bariatric surgery among adolescents with severe obesity

OBJECTIVE

To assess subclinical kidney injury in adolescents with severe obesity by measuring biomarkers of early kidney disease and to assess changes in the levels of these biomarkers following bariatric procedures.

METHODS

Twenty-two adolescents undergoing bariatric surgery with no microalbuminuria and normal kidney function were selected. Urinary NGAL, IL-18, and KIM-1 were measured at baseline, 6 and 12 months postoperatively. Biomarker levels were compared to 44 age-gender-matched lean controls.

RESULTS

Subjects with obesity had a mean baseline BMI of 48 kg/m(2) that decreased by 34% at 1-year follow-up. Urine NGAL, IL-18, and KIM-1 were significantly elevated in subjects with obesity compared to lean controls at baseline. The obese cohort had a further significant increase in NGAL and KIM-1 at 6 months, followed by decline at 1 year. The overall change in levels of all three biomarkers through 1 year after surgery, however, was not significant compared to baseline.

CONCLUSIONS

Adolescent severe obesity is associated with increased urinary excretion of novel biomarkers of kidney injury, despite no microalbuminuria or decreased kidney function. This subclinical kidney injury persists 1 year after significant weight loss induced by bariatric surgery, suggesting that close, long-term follow-up of kidney status is warranted in these adolescents.

[Role of kidney injury molecule-1 (KIM-1) for inhospital event risk assessment after coronary artery bypass surgery]

AIM

To assess value of kidney injury molecule-1 (KIM-1) for prediction of inhospital events in CAD patients undergoing coronary artery bypass graft (CABG) surgery.

MATERIAL AND METHODS

We analyzed postoperative course of 719 patients subjected to CABG in Research Institute for Complex Issues of Cardiovascular Diseases between March, 2011 and April, 2012. In all patients we measured creatinine concentrations, glomerular filtration rate (GFR) by MDRD and urine KIM-1 levels before and on day 7 after CABG. Major unfavorable events (myocardial infarction, stroke or transient ischemic attack, acute or decompensated chronic renal failure or remediastinotomy) were registered during hospital stay. The EuroSCORE (European System for Cardiac Operative Risk Evaluation) risk of operative mortality was calculated for each patient.

RESULTS

Patients with different EuroSCORE risk had similar serum creatinine levels while KIM-1 concentrations in urine were significantly higher in patients with moderate and high EuroSCORE risk as compared with low-risk patients. Patients who experienced postoperative events had significantly higher KIM-1 both before and after surgery while there were no differences in such renal dysfunction markers as creatinine and GFR.

CONCLUSION

Preoperative elevated KIM-1 can act as a marker of complicated postoperative period after CABG.

NGAL, L-FABP, and KIM-1 in comparison to established markers of renal dysfunction

BACKGROUND

New urinary biomarkers like neutrophil gelatinase-associated lipocalin (NGAL), liver-type fatty acid binding protein (L-FABP), and kidney injury molecule-1 (KIM-1) open the opportunity to detect kidney injuries in early stages. Our study aimed at evaluating NGAL, L-FABP, and KIM-1 in comparison to established markers of urine protein differentiation for detection of renal dysfunction.

METHODS

On the basis of the PROTIS expert system (for differentiation of glomerulo-/tubulopathy) urine and plasma samples of 263 randomly selected patients were routinely examined (urine: total protein, albumin, IgG, α1-microglobulin, creatinine, and dip stick results for leukocytes, blood, protein, glucose, pH, and nitrite; plasma: creatinine and cystatin C) followed by the analysis of the new urine biomarkers NGAL (CMIA), L-FABP (ECLIA), and KIM-1 (ELISA).

RESULTS

Of the three new markers L-FABP showed the highest correlation with α1-microglobulin (r=0.76, p<0.01) and was closest associated with the degree of tubular proteinuria assessed by the PROTIS system. NGAL distinguished the PROTIS proteinuria groups with distinctive tubular proteinurias from the controls as well, but revealed a marked diagnostic influence by leukocyturia. Urinary KIM-1 revealed only a weak diagnostic value for the detection of renal injury.

CONCLUSIONS

Urinary NGAL and L-FABP proved to be promising candidates for detecting injuries of the renal tubular system over a broad range of clinical conditions. L-FABP showed a better diagnostic performance and a lower interference by leukocyturia and hematuria than NGAL. Both markers may serve as sensitive tissue injury markers in addition to the established markers of renal functional impairment.

Association of urinary KIM-1, L-FABP, NAG and NGAL with incident end-stage renal disease and mortality in American Indians with type 2 diabetes mellitus

AIMS/HYPOTHESIS

Kidney injury molecule 1 (KIM-1), liver fatty acid-binding protein (L-FABP), N-acetyl-β-D-glucosaminidase (NAG) and neutrophil gelatinase-associated lipocalin (NGAL) are urinary biomarkers of renal tubular injury. We examined their association with incident end-stage renal disease (ESRD) and all-cause mortality in American Indians with type 2 diabetes.

METHODS

Biomarker concentrations were measured in baseline urine samples in 260 Pima Indians who were followed for a median of 14 years. HRs were reported per SD of creatinine (Cr)-normalised log-transformed KIM-1, NAG and NGAL, and for three categories of L-FABP.

RESULTS

During follow-up, 74 participants developed ESRD and 101 died. Median concentrations of KIM-1/Cr, NAG/Cr and NGAL/Cr and the proportion of detectable L-FABP were highest in those with macroalbuminuria (p < 0.001 for KIM-1/Cr, NAG/Cr and L-FABP; p = 0.006 for NGAL/Cr). After multivariable adjustment, NGAL/Cr was positively associated with ESRD (HR 1.59, 95% CI 1.20, 2.11) and mortality (HR 1.39, 95% CI 1.06, 1.82); L-FABP/Cr was inversely associated with ESRD (HR [for highest vs lowest tertile] 0.40, 95% CI 0.19, 0.83). Addition of NGAL/Cr to models that included albuminuria and glomerular filtration rate increased the c-statistic for predicting ESRD from 0.828 to 0.833 (p = 0.001) and for death from 0.710 to 0.722 (p = 0.018). Addition of L-FABP/Cr increased the c-statistic for ESRD from 0.828 to 0.832 (p = 0.042).

CONCLUSIONS/INTERPRETATION

In Pima Indians with type 2 diabetes, urinary concentrations of NGAL and L-FABP are associated with important health outcomes, but they are unlikely to add to risk prediction with standard markers in a clinically meaningful way given the small increase in the c-statistic.

Determination of early urinary renal injury markers in obese children

BACKGROUND

Obesity is an important health issue, the prevalence of which is increasing in childhood. The aim of this study was to examine urinary renal injury markers in order to determine the renal effect of obesity and its comorbidities in a pediatric population.

METHODS

Eighty-four obese children and 64 healthy control subjects were enrolled in the study. We checked their urine using N-acetyl-beta-D-glucosaminidase (NAG), neutrophil gelatinase-associated lipocalin (NGAL), kidney injury molecule-1 (KIM-1), and microalbumin as renal injury markers. Associations of renal damage markers with hypertension, an impaired glucose tolerance test, and insulin resistance were assessed.

RESULTS

Obese individuals had higher urinary NAG and KIM-1 values compared to those of healthy controls (p = 0.027, p = 0.026). There was no difference in urinary NGAL between obese and lean subjects (p = 0.885). Urinary renal injury markers were not statistically different in the obese group when checked for impaired glucose tolerance, insulin resistance, and hypertension (p > 0.05).

CONCLUSIONS

This study shows that urinary NAG and KIM-1 could be used as a screening method for detection of early renal damage in obese children.

Low-level cadmium exposure and effects on kidney function

OBJECTIVES

The nephrotoxicity of cadmium at low levels of exposure, measured by urinary cadmium, has recently been questioned since co-excretion of cadmium and proteins may have causes other than cadmium toxicity. The aim of this study was to explore the relation between kidney function and low or moderate cadmium levels, measured directly in kidney biopsies.

METHODS

We analysed cadmium in kidney biopsies (K-Cd), blood (B-Cd) and urine (U-Cd) from 109 living kidney donors in a cross-sectional study. We measured glomerular filtration rate (GFR), cystatin C in serum, albumin, β-2-microglobulin (B2M), retinol-binding protein (RBP), α-1-microglobulin (A1M), N-acetyl-β-d-glucosaminidase and kidney injury molecule 1 (KIM-1) in 24 h and overnight urine.

RESULTS

We found significant positive associations between A1M excretion and K-Cd in multiple regression models including age, sex, weight, smoking and urinary flow rate. This association was also present in never-smokers. A1M was also positively associated with B-Cd and U-Cd. GFR and the other biomarkers of kidney function were not associated with K-Cd. GFR estimated from serum cystatin C showed a very poor correlation with measured GFR. KIM-1, RBP and possibly albumin were positively associated with U-Cd, but only in overnight urine. No associations were found with B2M.

CONCLUSIONS

Our results suggest that A1M in urine is a sensitive biomarker for effects of low-level cadmium exposure. A few associations between other renal biomarkers and U-Cd, but not K-Cd, were probably caused by physiological co-excretion or chance.

Proximal tubule dysfunction is associated with podocyte damage biomarkers nephrin and vascular endothelial growth factor in type 2 diabetes mellitus patients: a cross-sectional study

BACKGROUND

There is an ongoing debate as to whether early diabetic nephropathy in Type 2 diabetes mellitus may be attributed to the glomerulus or to the proximal tubule. Urinary excretion of nephrin and vascular endothelial growth factor may increase even in the normoalbuminuria stage. In the course of diabetic nephropathy, the proximal tubule may be involved in the uptake of urinary nephrin and vascular endothelial growth factor.

MATERIALS AND METHODS

Two groups of consecutive Type 2 diabetes mellitus outpatients (38 normo-, 32 microalbuminuric) and 21 healthy subjects were enrolled in a cross-sectional study and evaluated concerning the relation of proximal tubule dysfunction with the podocyte biomarkers excretion, assessed by ELISA methods. The impact of advanced glycation end-products on this relation was also queried.

RESULTS

Urinary alpha1-microglobulin and kidney injury molecule-1 correlated with urinary albumin:creatinine ratio (R2 = 0.269; p < 0.001; R2 = 0.125; p < 0.001), nephrinuria (R2 = 0.529; p<0.001; R2 = 0.203; p < 0.001), urinary vascular endothelial growth factor (R2 = 0.709; p < 0.001; R2 = 0.360; p < 0.001), urinary advanced glycation end-products (R2 = 0.578; p < 0.001; R2 = 0.405; p < 0.001), serum cystatin C (R2 = 0.130; p < 0.001; R2 = 0.128; p<0.001), and glomerular filtration rate (R2 = 0.167; p < 0.001; R2 = 0.166; p < 0.001); nephrinuria and urinary vascular endothelial growth factor correlated with urinary albumin:creatinine ratio (R2 = 0.498; p < 0.001; R2 = 0.227; p<0.001), urinary advanced glycation end-products (R2 = 0.251; p < 0.001; R2 = 0.308; p < 0.001), serum cystatin C (R2 = 0.157; p < 0.001; R2 = 0.226; p < 0.001), and glomerular filtration rate (R2 = 0.087; p = 0.007; R2 = 0.218; p < 0.001).

CONCLUSIONS

In Type 2 diabetes mellitus there is an association of proximal tubule dysfunction with podocyte damage biomarkers, even in the normoalbuminuria stage. This observation suggests a potential role of the proximal tubule in urinary nephrin and urinary vascular endothelial growth factor processing in early diabetic nephropathy, a fact which could be related to advanced glycation end-products intervention. Podocyte damage and proximal tubule dysfunction biomarkers could be validated as a practical approach to the diagnosis of early diabetic nephropathy by further studies on larger cohorts.

Evidence of uncoupling between renal dysfunction and injury in cardiorenal syndrome: insights from the BIONICS study

OBJECTIVE

The objective of the study was to assess urinary biomarkers of renal injury for their individual or collective ability to predict Worsening renal function (WRF) in patients with acutely decompensated heart failure (ADHF).

METHODS

In a prospective, blinded international study, 87 emergency department (ED) patients with ADHF were evaluated with biomarkers of cardiac stretch (B type natriuretic peptide [BNP] and its amino terminal equivalent [NT-proBNP], ST2), biomarkers of renal function (creatinine, estimated glomerular filtration rate [eGFR]) and biomarkers of renal injury (plasma neutrophil gelatinase associated lipocalin [pNGAL], urine kidney injury molecule-1 [KIM-1], urine N-acetyl-beta-D-glucosaminidase [NAG], urine Cystatin C, urine fibrinogen). The primary endpoint was WRF.

RESULTS

26% developed WRF; baseline characteristics of subjects who developed WRF were generally comparable to those who did not. Biomarkers of renal function and urine biomarkers of renal injury were not correlated, while urine biomarkers of renal injury correlated between each other. Biomarker concentrations were similar between patients with and without WRF except for baseline BNP. Although plasma NGAL was associated with the combined endpoint, none of the biomarker showed predictive accuracy for WRF.

CONCLUSIONS

In ED patients with ADHF, urine biomarkers of renal injury did not predict WRF. Our data suggest that a weak association exists between renal dysfunction and renal injury in this setting (Clinicaltrials.gov NCT#0150153).

Nonalbuminuric proteinuria as a biomarker for tubular damage in early development of nephropathy with type 2 diabetic patients

AIM

The aim of this study was to evaluate the association between urinary nonalbumin protein (NAP) and urinary tubular markers in early diabetic nephropathy.

METHODS

Urinary NAP was measured in 118 patients with type 2 diabetes with estimated glomerular filtration rates (eGFR) ≥60 mL/min/1.73 m². Urine levels of tubular markers [kidney injury molecule (KIM)-1, neutrophil gelatinase-assoicated lipocalin (NGAL) and liver-type fatty acid-binding protein (L-FABP)] were measured by using an Enzyme-linked immunosorbent assay (ELISA). Patients were divided into three groups according to urinary NAP values.

RESULTS

The urine levels of KIM-1, NGAL and L-FABP were significantly higher in the third tertile group than in the first tertile group (all p < 0.001). There was a significant positive correlation between NAP and each tubular marker (KIM-1, NGAL and L-FABP) in univariate analysis (all p < 0.001). Urinary NAP was positively correlated with all urinary tubular markers after adjustment for age, duration of diabetes, systolic blood pressure, eGFR, low-density lipoprotein cholesterol, HbA1c and albumin-to-creatinine ratio (KIM-1 r = 0.170, p < 0.001; NGAL r = 0.142, p < 0.015 and L-FABP r = 0.262, p < 0.001). In normoalbuminuric patients (n = 58), urinary NAP was also significantly correlated with NGAL and L-FABP in multivariate regression analyses (r = 0.302, p = 0.030 and r = 0.430, p = 0.001).

CONCLUSIONS

These findings suggest that urinary NAP reflects tubular damage in the early-stage type 2 diabetic nephropathy (eGFR ≥ 60 mL/min/1.73 m²). We suggest that urinary NAP could be used as a biomarker for tubular damage in clinical practice.

Hsp72 is a novel biomarker to predict acute kidney injury in critically ill patients

BACKGROUND AND OBJECTIVES

Acute kidney injury (AKI) complicates the course of disease in critically ill patients. Efforts to change its clinical course have failed because of the fail in the early detection. This study was designed to assess whether heat shock protein (Hsp72) is an early and sensitive biomarker of acute kidney injury (AKI) compared with kidney injury molecule (Kim-1), neutrophil gelatinase-associated lipocalin (NGAL), and interleukin-18 (IL-18) biomarkers.

METHODS

A total of 56 critically ill patients fulfilled the inclusion criteria. From these patients, 17 developed AKI and 20 were selected as controls. In AKI patients, Kim-1, IL-18, NGAL, and Hsp72 were measured from 3 days before and until 2 days after the AKI diagnosis and in no-AKI patients at 1, 5 and 10 days after admission. Biomarker sensitivity and specificity were determined. To validate the results obtained with ROC curves for Hsp72, a new set of critically ill patients was included, 10 with AKI and 12 with no-AKI patients.

RESULTS

Urinary Hsp72 levels rose since 3 days before the AKI diagnosis in critically ill patients; this early increase was not seen with any other tested biomarkers. Kim-1, IL-18, NGAL, and Hsp72 significantly increased from 2 days before AKI and remained elevated during the AKI diagnosis. The best sensitivity/specificity was observed in Kim-1 and Hsp72: 83/95% and 100/90%, respectively, whereas 1 day before the AKI diagnosis, the values were 100/100% and 100/90%, respectively. The sensibility, specificity and accuracy in the validation test for Hsp72 were 100%, 83.3% and 90.9%, respectively.

CONCLUSIONS

The biomarker Hsp72 is enough sensitive and specific to predict AKI in critically ill patients up to 3 days before the diagnosis.

A pilot study to evaluate renal hemodynamics in cirrhosis by simultaneous glomerular filtration rate, renal plasma flow, renal resistive indices and biomarkers measurements

BACKGROUND

Renal hemodynamic measurements are complicated to perform in patients with cirrhosis, yet they provide the best measure of risk to predict hepatorenal syndrome (HRS). Currently, there are no established biomarkers of altered renal hemodynamics in cirrhosis validated by measured renal hemodynamics.

METHODS

In this pilot study, simultaneous measurements of glomerular filtration rate (GFR), renal plasma flow (RPF), renal resistive indices and biomarkers were performed to evaluate renal hemodynamic alterations in 10 patients with cirrhosis (3 patients without ascites, 5 with diuretic-sensitive and 2 diuretic-refractory ascites).

RESULTS

Patients with diuretic-refractory ascites had the lowest mean GFR (36.5 ml/min/1.73 m(2)) and RPF (133.6 ml/min/1.73 m(2)) when compared to those without ascites (GFR 82.9 ml/min/1.73 m(2), RPF 229.9 ml/min/1.73 m(2)) and with diuretic-sensitive ascites (GFR 82.3 ml/min/1.73 m(2), RPF 344.1 ml/min/1.73 m(2)). A higher mean filtration fraction (FF) (GFR/RPF 0.36) was noted among those without ascites compared to those with ascites. Higher FF in patients without ascites is most likely secondary to the vasoconstriction in the efferent glomerular arterioles (normal FF ~0.20). In general, renal resistive indices were inversely related to FF. While patients with ascites had lower FF and higher right kidney main and arcuate artery resistive indices, those without ascites had higher FF and lower right kidney main and arcuate artery resistive indices. While cystatin C and β2-microglobulin performed better compared to Cr in estimating RPF, β-trace protein, β2-microglobulin, and SDMA, and (SDMA+ADMA) performed better in estimating right kidney arcuate artery resistive index.

CONCLUSION

The results of this pilot study showed that identification of non-invasive biomarkers of reduced RPF and increased renal resistive indices can identify cirrhotics at risk for HRS at a stage more amenable to therapeutic intervention and reduce mortality from kidney failure in cirrhosis.

[Predict value of monitoring changes of urinary neutrophil gelatinase-associated lipocalin and kidney injury molecule-1 after coronary angiography and percutaneous coronary intervention on early diagnosis of contrast-induced nephropathy]

OBJECTIVE

To explore the predict value of monitoring changes of urinary neutrophil gelatinase-associated lipocalin (NGAL) and kidney injury molecule-1(KIM-1) after coronary angiography (CAG) and percutaneous coronary intervention (PCI) on the early diagnosis of contrast-induced nephropathy(CIN).

METHODS

One hundred and sixty patients underwent CAG and PCI were enrolled in this prospective study. There were 14 patients with CIN and non-CIN patients were selected with the proportion of 2: 1 (n = 28).Serum creatinine (SCr) was measured before and at 24, 48 and 72 h after the procedure. Urinary NGAL and KIM-1 were measured before and at 4 and 24 h after the procedure. The relationship between NGAL, KIM-1 and CIN were analyzed. Receiver operating characteristic (ROC) curve and area under the ROC curve (AUC) were used to analyze the diagnostic sensitivity and specificity of CIN by urinary NGAL and KIM-1.

RESULTS

(1) The values of urinary NGAL was significantly higher in the CIN group than in non-CIN group at 4 h after CAG or PCI (P < 0.01); the value of urinary NGAL was significantly increased from the baseline to 4 h after the procedure in the CIN group (P < 0.01). (2) Uurinary KIM-1 levels of CIN group was significantly higher than in non-CIN group at 24 h after the CAG or PCI (P < 0.01) ; the urinary KIM-1 levels was significantly increased from baseline to 24 h after the procedure in the CIN group (P < 0.01). (3) Pearson correlation analysis showed that there was a positive correlation between urinary NGAL and SCr (r = 0.814, P < 0.01) and urinary KIM-1(r = 0.758, P < 0.01) in the CIN group. (4) ROC curve analysis showed that the AUC for urinary NGAL was 0.897. When the cut-off value of NGAL was set at 11.950 µg/L, the sensitivity and specificity for the diagnosis of CIN were 92.9% and 71.4%, respectively. The AUC for urinary KIM-1 was 0.839. With the cut-off value of urinary KIM-1 set as 4.595 µg/L, the diagnostic sensitivity and specificity for CIN were 85.7% and 71.4%, respectively.

CONCLUSIONS

Urinary NGAL serves as a good biomarker for early diagnosis of CIN suggesting acute kidney injury at 4 h post CAG and PCI. Urinary KIM-1 can reflect the change of renal function after contrast injection earlier than SCr and may also be a good biomarker for early diagnosis of CIN.

Kidney injury molecule (KIM)-1 is associated with insulin resistance: results from two community-based studies of elderly individuals

BACKGROUND AND OBJECTIVES

Insulin resistance has been shown to be closely associated with glomerular filtration rate and urinary albumin/creatinine ratio, even prior to the development of diabetes. Urinary kidney injury molecule 1 (KIM-1) is a novel, highly specific marker of kidney tubular damage. The role of insulin resistance in the development of kidney tubular damage is not previously reported. Thus, we aimed to investigate the associations between insulin sensitivity (assessed by HOMA) and urinary KIM-1.

DESIGN, SETTING, PARTICIPANTS AND MEASUREMENTS

Two community-based cohorts of elderly individuals were investigated: Prospective Investigation of the vasculature in Uppsala seniors (PIVUS, n=701; mean age 75 years, 52% women); and Uppsala Longitudinal Study of adult men (ULSAM, n=533; mean age 78 years).

RESULTS

Lower insulin sensitivity was associated with higher urinary KIM-1 in both cohorts after adjustments for age, BMI, blood pressure, antihypertensive treatment, glomerular filtration rate, and urinary albumin-creatinine ratio (PIVUS: regression coefficient for 1-SD higher HOMA-IR 0.11, 95% CI 0.03-0.20, p=0.009, and ULSAM: 0.13, 95% CI 0.04-0.22, p=0.007). Results were similar in individuals without diabetes, with normal kidney function and normo-albuminuria.

CONCLUSIONS

Our findings in elderly individuals support the notion that the interplay between an impaired glucose metabolism and renal tubular damage is evident even prior to the development of diabetes and overt kidney disease.

Diagnostic value of urinary kidney injury molecule 1 for acute kidney injury: a meta-analysis

Background

Urinary Kidney Injury Molecule 1 (KIM-1) is a proximal tubular injury biomarker for early detection of acute kidney injury (AKI), with variable performance characteristics depending on clinical and population settings.

Methods

Meta-analysis was performed to assess the diagnostic value of urinary KIM-1 in AKI. Relevant studies were searched from MEDLINE, EMBASE, Pubmed, Elsevier Science Direct, Scopus, Web of Science, Google Scholar and Cochrane Library. Meta-analysis methods were used to pool sensitivity and specificity and to construct summary receiver operating characteristic (SROC) curves.

Results

A total of 2979 patients from 11 eligible studies were enrolled in the analysis. Five prospective cohorts, two cross-sectional and four case-control studies were identified for meta-analysis. The estimated sensitivity of urinary KIM-1 for the diagnosis of AKI was 74.0% (95% CI, 61.0%–84.0%), and specificity was 86.0% (95% CI, 74.0%–93.0%). The SROC analysis showed an area under the curve of 0.86(0.83–0.89). Subgroup analysis suggested that population settings and detection time were the key factors affecting the efficiency of KIM-1 for AKI diagnosis.

Limitation

Various population settings, different definition of AKI and Serum creatinine level used as the standard might have influence on AKI diagnosis. The relatively small number of studies and heterogeneity between them also affected the evaluation.

Conclusion

Urinary KIM-1 may be a promising biomarker for early detection of AKI with considerable predictive value, especially for cardiac surgery patients, and its potential value needs to be validated in large studies and across a broader scope of clinical settings.

Reference intervals for urinary renal injury biomarkers KIM-1 and NGAL in healthy children

AIM

The aim of this study was to establish reference intervals in healthy children for two novel urinary biomarkers of acute kidney injury, kidney injury molecule-1 (KIM-1) and neutrophil gelatinase-associated lipocalin (NGAL).

MATERIALS & METHODS

Urinary biomarkers were determined in samples from children in the UK (n = 120) and the USA (n = 171) using both Meso Scale Discovery (MSD) and Luminex-based analytical approaches.

RESULTS

95% reference intervals for each biomarker in each cohort are presented and stratified by sex or ethnicity where necessary, and age-related variability is explored using quantile regression. We identified consistently higher NGAL concentrations in females than males (p < 0.0001), and lower KIM-1 concentrations in African-Americans than Caucasians (p = 0.02). KIM-1 demonstrated diurnal variation, with higher concentrations in the morning (p < 0.001).

CONCLUSION

This is the first report of reference intervals for KIM-1 and NGAL using two analytical methods in a healthy pediatric population in both UK and US-based populations.

Urinary biomarkers and renal near-infrared spectroscopy predict intensive care unit outcomes after cardiac surgery in infants younger than 6 months of age

OBJECTIVE

To assess the ability of urinary acute kidney injury biomarkers and renal near-infrared spectroscopy (NIRS) to predict outcomes in infants after surgery for congenital heart disease.

METHODS

Urinary levels of neutrophil gelatinase-associated lipocalin (NGAL), interleukin-18 (IL-18), kidney injury molecule-1 (KIM-1), and cystatin C were measured preoperatively and postoperatively in 49 infants younger than 6 months of age. Renal NIRS was monitored for the first 24 hours after surgery. A composite poor outcome was defined as death, the need for renal replacement therapy, prolonged time to first extubation, or prolonged intensive care unit length of stay.

RESULTS

Forty-two (86%) patients had acute kidney injury as indicated by at least Acute Kidney Injury Network/Kidney Disease: Improving Global Outcomes (AKIN/KDIGO) stage 1 criteria, and 17 (35%) patients had poor outcomes, including 3 deaths. With the exception of KIM-1, all biomarkers demonstrated significant increases within 24 hours postoperatively among patients with poor outcomes. Low levels of NGAL and IL-18 demonstrated high negative predictive values (91%) within 2 hours postoperatively. Poor outcome infants had greater cumulative time with NIRS saturations less than 50% (60 vs 1.5 minutes; P = .02) in the first 24 hours.

CONCLUSIONS

Within the first 24 hours after cardiopulmonary bypass, infants at increased risk for poor outcomes demonstrated elevated urinary NGAL, IL-18, and cystatin C and increased time with low NIRS saturations. These findings suggest that urinary biomarkers and renal NIRS may differentiate patients with good versus poor outcomes in the early postoperative period, which could assist clinicians when counseling families and inform the development of future clinical trials.

Biomarkers of acute kidney injury in pediatric cardiac surgery

OBJECTIVES

Acute kidney injury (AKI) is a significant problem in children undergoing cardiopulmonary bypass (CPB). The aims of this study were to assess the diagnostic validity of serum CysC (sCysC), serum neutrophil gelatinase lipocalin (sNGAL), urine neutrophil gelatinase lipocalin (uNGAL), urine kidney injury molecule (uKIM)-1, and urine liver fatty acid-binding protein (uL-FABP) to predict AKI presence and severity in children undergoing CPB.

DESIGN AND METHODS

We performed a prospective single-center evaluation of sCysC, sNGAL, uNGAL, uKIM-1 and uL-FABP at 0, 2, 6, 24 and 48 h postoperatively in children undergoing CPB during cardiac surgery. AKI was defined as ≥25% decrease in the estimated creatinine clearance (eCCl) from pre-operative baseline at 48h after surgery.

RESULTS

Of the 112 patients, 18 patients (16.1%) developed AKI; four of them needed acute dialysis treatment and three AKI patients died. In the AKI compared to the non-AKI group, sCysC at 2h, and uNGAL and uL-FABP at 2-48 h were significantly increased, as well as CPB, aortic cross clamp time and length of hospital stay. Biomarkers increased with worsening AKI severity. At 2h after CPB the best accuracy for diagnosis of AKI had uL-FABP and sCysC with area under the receiver operator curve (AUC) of 0.89 and 0.73, respectively. At 6 and 24h after CPB the best AUC was found for uL-FABP (0.75 and 0.87 respectively) and for uNGAL (0.70 and 0.93, respectively).

CONCLUSIONS

sCysC, uNGAL and uL-FABP are reliable early predictors for AKI after CPB. By allowing earlier timing of injury and earlier intervention, they could improve AKI outcome.

[Prevention of contrast-induced nephropathy in the context of evidence-based medicine]

The paper considers the mechanisms of development of contrast-induced nephropathy in the use of iodinated radiopaque contrast agents (RCAs), as well as the criteria of their assessment. It gives different existing recommendations for prevention of the nephrotoxic effects of RCAs.

Review and discussion of tubular biomarkers in the diagnosis and management of diabetic nephropathy

The prevalence of diabetic nephropathy has tremendously increased with the relentless rise in the incidence of diabetes over the last couple decades. Diabetic nephropathy is a leading cause of morbidity and mortality, and it invariably leads to an end-stage renal disease (ESRD). In an effort to delay the onset of ESRD systematic screening and appropriate management are needed to evaluate the progression of renal damage in diabetic nephropathy. The reliability of current tests in predicting the onset, progression and response to various regimens for diabetic nephropathy is still under debate; and it has engendered a search for more sensitive and specific urinary biomarkers, especially those reflective of tubular dysfunctions. It is well-known that there is a good correlation between the degree of damage to the tubulo-interstitial compartment and the deterioration of renal functions. In view of this, the utility of urinary biomarkers, reflective of tubular injury, reported in the literature is discussed in this brief review.

Current developments in early diagnosis of acute kidney injury

Acute kidney injury (AKI) is a very frequent and serious clinical problem, accounting for overall high morbidity and mortality. Up to date, mortality due to AKI is virtually unchanged over the past 50 years. This may partly be explained due to a delay in initiating renal protective and appropriate therapeutic measures since until now there are no reliable early-detecting biomarkers. The gold standard, serum creatinine, displays poor specificity and sensitivity with regard to identification of the incipient phase of AKI, and this is also true for cystatin C. We aimed to review novel biomarkers of AKI in urine and serum which have now progressed to the clinical phase. The main focus refers to their diagnostic and prognostic value. For this purpose, a web-based literature search using PubMed was performed comprising the following terms: renal failure, acute kidney injury and biomarkers. New molecules such as neutrophil gelatinase-associated lipocalin (NGAL), kidney injury molecule-1 (KIM-1), N-acetyl-β-D-glucosaminidase (NAG), monocyte chemotactic peptide (MCP-1), Il-18, liver-type fatty acid-binding protein (L-FABP) and Netrin-1 are available and represent promising new markers that, however, need to be further evaluated in the clinical setting for suitability. In clinical settings with incipient AKI, not only the development and the implementation of more sensitive, practicable and accurate biomarkers are required for well-timed treatment initiation. Just as important is a substantial improvement of refined and applicable prophylactic therapeutic options in these situations. Before full adoption in clinical practice can be accomplished, adequately powered clinical trials testing a row of biomarkers are strongly warranted.

Noninvasive analyses of kidney injury molecule-1 messenger RNA in kidney transplant recipients with graft dysfunction

BACKGROUND

Kidney graft fibrosis is a major factor related to chronic loss of kidney function. At present, the finding of fibrosis depends on the analysis of tissue in the renal biopsy, which has important limitations. In this study, we evaluated the messenger mRNA transcription and gene expression of kidney injury molecule-1 (KIM-1) in kidney tissue and in urinary sediment cells of kidney transplant patients with graft dysfunction aiming at the development of techniques that may allow the noninvasive diagnosis of interstitral fibrosis/tubular atrophy (IF/TA).

PATIENTS AND METHODS

RNA extracted from cells in tissue and urine of 77 renal transplant patients whose biopsies were classified according to the Banff scheme-2007. Four diagnostic groups were established: (1) acute tubular necrosis (n = 9); (2) acute rejection (n = 49); (3) acute calcineurin inhibitors nephrotoxicity (n = 10); and (4) interstitial fibrosis and tubular atrophy (IFTA, n = 29). Tissue and urine cell RNA was amplified and quantification were made by real-time polymerase chain reactron. Data from the quantification of gene expression are presented as median and 25th to 75th percentiles.

RESULTS

Messenger RNA levels of the KIM-1 gene were higher in the biopsies (26.17; 3.38-294.53) and urinary sediment cells (0.09; 0-5.81) of the patients classified as having IF/TA as compared with all others groups. A significant correlation between gene expression in samples of urine and tissue cells was found (P < .01).

CONCLUSION

These initial data suggests that KIM-1 gene mRNA quantification can be used as a noninvasive biomarker of IF/TA.

Detection of soluble antigen and DNA of Trypanosoma cruzi in urine is independent of renal injury in the guinea pig model

The diagnosis of Chagas disease in humans is generally limited to the detection of specific antibodies. Detection of T. cruzi antigens in urine has been reported previously, but is not used in the diagnosis. In this study, soluble T. cruzi antigens and DNA were detected in urine samples and were associated with kidney injury and systemic detection of the parasite. We used 72 guinea pigs infected with T. cruzi Y strain and 18 non-infected guinea pigs. Blood, kidney, heart and urine samples were collected during the acute phase and chronic phase. Urine samples were concentrated by ultrafiltration. Antigens were detected by Western Blot using a polyclonal antibody against trypomastigote excretory-secretory antigen (TESA). T. cruzi DNA was detected by PCR using primers 121/122 and TcZ1/TcZ2. Levels of T. cruzi DNA in blood, heart and kidney were determined by quantitative PCR. T. cruzi antigens (75 kDa, 80 kDa, 120 kDa, 150 kDa) were detected in the acute phase (67.5%) and the chronic phase (45%). Parasite DNA in urine was detected only in the acute phase (45%). Kidney injury was characterized by high levels of proteinuria, kidney injury molecule-1 (KIM-1) and urea, and some histopathological changes such as inflammation, necrosis, fibrosis and scarce parasites. The detection of antigens and DNA in urine was associated with the presence of parasite DNA in blood and heart and with high levels of parasite DNA in blood, but not with the presence of parasite in kidney or kidney injury. These results suggest that the detection of T. cruzi in urine could be improved to be a valuable method for the diagnosis of Chagas disease, particularly in congenital Chagas disease and in immunocompromised patients.

Diabetic nephropathy: traditional to proteomic markers

Diabetic nephropathy (DN) is one of the major microvascular complications of diabetes and it is defined as a rise in the urinary albumin excretion (UAE) rate and abnormal renal function. Currently, changes in albuminuria are considered a hallmark of onset or progression of DN. However, some patients with diabetes have advanced renal pathological changes and progressive kidney function decline even if urinary albumin levels are in the normal range, indicating that albuminuria is not the perfect marker for the early detection of DN. The present article provides an overview of the literature reporting some relevant biomarkers that have been found to be associated with DN and that potentially may be used to predict the onset and/or monitor the progression of nephropathy. In particular, biomarkers of renal damage, inflammation, and oxidative stress may be useful tools for detection at an early stage or prediction of DN. Proteomic-based biomarker discovery represents a novel strategy to improve diagnosis, prognosis and treatment of DN; however, proteomics-based approaches are not yet available in most of the clinical chemistry laboratories. The use of a panel with a combination of biomarkers instead of urinary albumin alone seems to be an interesting approach for early detection of DN, including markers of glomerular damage (e.g., albumin), tubular damage (e.g., NAG and KIM-1), inflammation (e.g., TNF-α) and oxidative stress (e.g., 8-OHdG) because these mechanisms contribute to the development and outcomes of this disease.

[Clinical study of kidney injury molecule-1 in the treatment of sepsis patients]

OBJECTIVE

To investigate the relationship between kidney injury molecule-1 (KIM-1) in urine and acute physiology and chronic health evaluation II (APACHEII) score, and the prognosis in the patients suffered from sepsis.

METHODS

In the perspective study, 56 patients in intensive care unit (ICU) from March 2010 to September 2011 suffered from sepsis were enrolled and treated according to the early goal-directed therapy (EGDT). The patients were divided into two groups according to the perform in EGDT or not within 6 hours (groupI, group II). Monitoring included APACHEII score, KIM-1, blood urea nitrogen (BUN) and creatinine (Cr) at before resuscitation (T0), 6 hours after resuscitation (T6 h), and 1 day (T1 d), 2 days (T2 d), 3 days (T3 d), 4 days (T4 d) and 5 days (T5 d) after ICU admission. According to the 28-day prognosis, all the patients were divided into survival group or death group.

RESULTS

The value of APACHEII score, urine KIM-1, BUN and Cr in groupI(n=30), decreased after fluid resuscitation and decreased to the lowest at T5 d. The value of APACHEII score, urine KIM-1, BUN and Cr in groupII(n=26), increased after failure of fluid resuscitation and increased to the highest at T5 d. The value of APACHEII score at T2 d and urine KIM-1 at T1 d in groupII were significantly higher than those in groupI (APACHEII score: 26.35±6.18 vs. 13.25±4.72, urine KIM-1: 4.721±1.432 μg/L vs. 0.909±0.325 μg/L, both P<0.05). The mortality in groupI was significantly lower than that in group II [10.0% (3/30) vs. 73.1% (19/26), P<0.05]. The value of APACHEII score, urine KIM-1, BUN and Cr in survival group (n=34) decreased with the clinical condition improved and decreased to the lowest at T5 d, while the value of APACHEII score, urine KIM-1, BUN and Cr in death group (n=22) increased and increased to the highest at T5 d. The value of APACHEII score at T1 d, and urine KIM-1 at T6 d in death group were significantly higher than those in survival group (APACHEII score:26.39±8.95 vs. 14.27±5.11, urine KIM-1:3.134±1.117 μg/L vs. 1.447±0.472 μg/L, both P<0.05).

CONCLUSIONS

KIM-1 in urine could be a good index for evaluation of sepsis, and it is helpful to understand the disease development by continuous surveillance. It is very important for the appraisal of prognosis, development and prognosis in sepsis, combined with APACHEII score.

Analytical and biological validation of a multiplex immunoassay for acute kidney injury biomarkers

BACKGROUND

Acute kidney injury (AKI) is a dynamic process that can involve inflammatory, hypoxic, and structural changes to the kidney. We evaluated a multiplex panel of markers representing different AKI mechanisms as a tool to provide integrated assessment of AKI status in a single assay.

METHODS

Urinary cystatin C (CysC), neutrophil gelatinase-associated lipocalin (NGAL), kidney injury molecule-1 (KIM-1) and interleukin-18 (IL-18) were measured by multiplex electrochemiluminescence immunoassay. Analytical performance was compared to the biological and pathological variation of these markers in human samples.

RESULTS

Linearity was established over a 3- to 4-log range for all markers, which spanned the reference ranges established from healthy donors. Imprecision was below 15%, comparing favorably with the observed biological variation of these markers. Control patients fell within donor-derived reference ranges for most markers, but a subset of patients showed CysC and KIM-1 elevations in the absence of documented AKI.

CONCLUSION

The multiplex assay is reliable for simultaneous quantitation of CysC, IL-18, KIM-1 and NGAL in human urine, and performs at levels sufficient for clinical application. The observed differences in biological variability and baseline levels suggest that clinical strategies to detect AKI will need to vary depending upon the specific markers used.

Mechanism-based urinary biomarkers to identify the potential for aminoglycoside-induced nephrotoxicity in premature neonates: a proof-of-concept study

Premature infants are frequently exposed to aminoglycoside antibiotics. Novel urinary biomarkers may provide a non-invasive means for the early identification of aminoglycoside-related proximal tubule renal toxicity, to enable adjustment of treatment and identification of infants at risk of long-term renal impairment. In this proof-of-concept study, urine samples were collected from 41 premature neonates (≤32 weeks gestation) at least once per week, and daily during courses of gentamicin, and for 3 days afterwards. Significant increases were observed in the three urinary biomarkers measured (Kidney Injury Molecule-1 (KIM-1), Neutrophil Gelatinase-associated Lipocalin (NGAL), and N-acetyl-β-D-glucosaminidase (NAG)) during treatment with multiple courses of gentamicin. When adjusted for potential confounders, the treatment effect of gentamicin remained significant only for KIM-1 (mean difference from not treated, 1.35 ng/mg urinary creatinine; 95% CI 0.05–2.65). Our study shows that (a) it is possible to collect serial urine samples from premature neonates, and that (b) proximal tubule specific urinary biomarkers can act as indicators of aminoglycoside-associated nephrotoxicity in this age group. Further studies to investigate the clinical utility of novel urinary biomarkers in comparison to serum creatinine need to be undertaken.

Clinical implication of urinary tubular markers in the early stage of nephropathy with type 2 diabetic patients

AIM

The aim of this study was to evaluate the association of urinary tubular markers, interleukin-18 (IL-18) and angiotensinogen with albuminuria in early nephropathy of type 2 diabetics.

METHODS

Urine levels of tubular markers (kidney injury molecule [KIM]-1, neutrophil gelatinase-associated lipocalin [NGAL] and liver-type fatty acid-binding protein [L-FABP]), proinflammatory marker (IL-18), and a marker of intrarenal renin-angiotensin system (RAS) status (angiotensinogen) were determined in 118 patients with type 2 diabetes mellitus and 25 non-diabetic controls with estimated glomerular filtration rate (eGFR) ≥ 60 mL/min/1.73 m(2).

RESULTS

Urinary levels of KIM-1, NGAL, IL-18 and angiotensinogen were significantly higher in macroalbuminuria group compared with control and normo- and microalbuminuria groups but not significantly different between control and normoalbuminuria group. Urinary tubular markers were positively correlated with urinary IL-18 and angiotensinogen, respectively. The urinary albuminuria was correlated with all investigated urinary markers in univariate analysis. After adjusting for several clinical parameters, urinary KIM-1, NGAL and angiotensinogen were significantly associated with albuminuria.

CONCLUSIONS

The results of this study suggest that urinary tubular markers may be independently associated with albuminuria in the early stage of nephropathy in type 2 diabetics (eGFR ≥ 60 mL/min/1.73 m(2)) and may reflect inflammatory processing and the activation of the intrarenal RAS.

Acute Kidney Injury (AKI) biomarker

The kidney has a remarkable capacity to withstand insults for an extended period of time. The sensitivities of individual renal cells to injury vary depending on their type, position in the nephron, local vascularization, and the nature of injury. The resulting kidney injury is a product of the interplay between cell dysfunction, cell death, proliferation, inflammation, and recovery. The Acute Kidney Injury Network (AKIN) defined Acute Kidney Injury (AKI) as "functional and structural disorder or signs of renal damage including any defect from blood and urine test, or tissue imaging that is less than 3 months". RIFLE (Risk, Injury, Failure, Loss, End-Stage Kidney Disease) criteria is the most frequently used system. Ideal biomarker for AKI should be affordable, quick and measurable, precise and accurate, with prognostic ability to define severity of renal dysfunction, specific for renal, increase in the early stage dysfunction, with high sensitivity and specificity. Efforts to detect AKI in the earlier stage has resulted in some promising biomarkers such as KIM-1, NGAL, IL-18, Clusterin, etc. Cystatin C is a biomarker for glomerular filtration function, while 2-microglobulin, 1-microglobulin, NAG, RBP, IL-18, NGAL, Netrin-1, KIM-1, Clusterin, Sodium Hydrogen Exchanger Isoform and Fetuin A are biomarkers for tubular reabsorption function.

Urinary tubular biomarkers in short-term type 2 diabetes mellitus patients: a cross-sectional study

The purpose of this study was to investigate the prevalence of tubular damage in short-term (less than five years) type 2 diabetes mellitus (T2DM) patients and to explore the correlation between tubular markers and their relationship with renal indices at different stages of diabetic nephropathy. A group of 101 short-term T2DM patients and 28 control subjects were recruited. Tubular markers, such as neutrophil gelatinase-associated lipocalin (NGAL), N-acetyl-β-D: -glucosaminidase (NAG), and kidney injury molecule 1 (KIM-1), as well as urinary albumin excretion were measured in voided urine. Glomerular filtration rate (GFR) was estimated via Macisaac's formula. The patients were further categorized into three groups, namely, the normoalbuminuria, microalbuminuria, and macroalbuminuria groups, according to their urine albumin/creatinine ratio (UACR). Urinary tubular markers were compared and their correlations with renal indices [UACR and estimated GFR (eGFR)] were analyzed among the different diabetic groups. Compared with the control group, Urinary NGAL [median (IQR)][83.6(41.4-138.7) μg/gcr vs. 32.9(26.1-64.5) μg/gcr], NAG [13.5(8.7-17.9) U/gcr vs. 7.6(6.5-13.0) U/gcr] and KIM-1 [120.0(98.4-139.9) ng/gcr vs. 103.1(86.8-106.2) ng/gcr] in the T2DM were all markedly increased. For all patients, urinary NGAL had stronger positive correlations with UACR than NAG (R = 0.556 vs. 0.305, both P < 0.05). In addition, only urinary NGAL showed a negative correlation with eGFR (R = -0.215, P < 0.05). Urinary KIM-1, however, showed no significant difference among the three T2DM groups and did not correlate with either UACR or eGFR. As UACR increased from the normoalbuminuria to the last macroalbuminuria group, all of the markers increased. However, only the concentrations of NGAL were statistically different among the three diabetic groups. The correlation between the tubular markers and their relationships with the renal indices differed markedly among the three T2DM groups. In conclusion, these results suggest that tubular damage is common in short-term T2DM patients. Urinary NGAL may be a promising early marker for monitoring renal impairment in short-term T2DM patients.

Changes of the tubular markers in type 2 diabetes mellitus with glomerular hyperfiltration

AIM

To assess whether glomerular hyperfiltration (GHF) could result in renal tubular damage in type 2 diabetes mellitus (T2DM) patients.

METHODS

Reference value of estimated glomerular filtration rate (eGFR) was determined in 248 healthy individuals based on serum CysC levels. GHF was defined as an eGFR exceeding the sex-specific 97.5th percentile in non-diabetic individuals. In the present study, 30 with GHF, 58 with norm-GFR T2DM, and 24 healthy controls were recruited. Tubular markers, such as urinary N-acetyl-β-D-glucosaminidase (NAG) and kidney injury molecule 1 (KIM-1), as well as serum and urinary neutrophil gelatinase-associated lipocalin (NGAL), were measured and compared. The correlation of these markers with eGFR was analyzed in the GHF group.

RESULTS

The GHF group had higher urinary NGAL and KIM-1 levels but lower serum NGAL level than the norm-GFR and control groups. Slightly decreased serum NGAL and increased urinary NGAL levels were also noted in the norm-GFR group compared with those of the controls. There was no statistical difference in the urinary NAG values among the three groups. Correlation analysis showed that eGFR was positively related to fasting blood glucose (FBG), HbA1c, urinary NGAL, and KIM-1, but negatively with serum NGAL in the GHF group.

CONCLUSION

Higher urinary tubular damage markers were found in T2DM patients with GHF than the norm-GFR and control groups, probably a direct proof that GHF is a deleterious factor for diabetic nephropathy.

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

BACKGROUND/AIMS

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

METHODS

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

RESULTS

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

CONCLUSION

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

The association between urinary kidney injury molecule 1 and urinary cadmium in elderly during long-term, low-dose cadmium exposure: a pilot study

BACKGROUND

Urinary kidney injury molecule 1 is a recently discovered early biomarker for renal damage that has been proven to be correlated to urinary cadmium in rats. However, so far the association between urinary cadmium and kidney injury molecule 1 in humans after long-term, low-dose cadmium exposure has not been studied.

METHODS

We collected urine and blood samples from 153 non-smoking men and women aged 60+, living in an area with moderate cadmium pollution from a non-ferrous metal plant for a significant period. Urinary cadmium and urinary kidney injury molecule 1 as well as other renal biomarkers (alpha1-microglobulin, beta2-microglobulin, blood urea nitrogen, urinary proteins and microalbumin) were assessed.

RESULTS

Both before (r = 0.20; p = 0.01) and after (partial r = 0.32; p < 0.0001) adjustment for creatinine, age, sex, past smoking, socio-economic status and body mass index, urinary kidney injury molecule 1 correlated with urinary cadmium concentrations. No significant association was found between the other studied renal biomarkers and urinary cadmium.

CONCLUSIONS

We showed that urinary kidney injury molecule 1 levels are positively correlated with urinary cadmium concentration in an elderly population after long-term, low-dose exposure to cadmium, while other classical markers do not show an association. Therefore, urinary kidney injury molecule 1 might be considered as a biomarker for early-stage metal-induced kidney injury by cadmium.

Biomarkers for early detection of sickle nephropathy

Renal complications affect nearly 30-50% of adults with sickle cell anemia (SCA), causing significant morbidity and mortality. Standard renal function tests like serum creatinine and glomerular filtration rate become abnormal in this disease only when renal damage has become extensive and largely irreversible. Moreover, not all patients develop sickle nephropathy (SN). Therefore, noninvasive biomarkers that predict early onset of SN are necessary. We performed a cross-sectional analysis for nephropathy in 116 patients with sickle cell disease, analyzing urinary kidney injury molecule-1 (KIM-1), liver-type fatty acid binding protein (L-FABP), N-acetyl-b-D-glucosaminidase (NAG), neutrophil gelatinase-associated lipocalin (NGAL) and transforming growth factor-β1 (TGF-β), together with conventional renal biomarkers (urine albumin and osmolality, and serum creatinine and cystatin C estimated GFR) during routine clinic visits when patients were at steady-state/baseline. We observed a distinct biomarker pattern: KIM-1 and NAG emerged as biomarkers with a strong association with albuminuria. Surprisingly, and in contrast to other acute/chronic renal disorders, NGAL, L-FABP, and TGF-β levels did not show any relationship with albuminuria in patients with SCA. Our study identifies potential biomarkers for SN, and suggests longitudinal validation of these biomarkers for early detection of SN, so that therapeutic interventions can be applied before renal damage becomes irreversible.

The early diagnosis of acute renal graft dysfunction: a challenge we face. The role of novel biomarkers

Acute graft dysfunction can be caused by ischaemic damage or immunological injury leading to serious consequences both in the short and long term. We are in a desperate need for biomarkers of immune and nonimmune injury at different time points of the transplantation time course, beginning from a potential kidney donors where acute kidney damage can pass unnoticed, during the early post-transplant periods to predict acute transplant dysfunction due to various causes and during long term follow up to predict chronic histological changes. The implementation of these novel biomarkers could increase the sensitivity of diagnosis and monitoring of kidney injury in kidney transplant recipients. Traditionally acute graft dysfunction is diagnosed by measuring serum creatinine concentrations. Unfortunately rise in serum creatinine is a late sign of kidney damage. It indicates rather predicts the damage. The treatment, in order to be effective, must be instituted very early after the initiating insult, well before the serum creatinine even begins to rise. Fortunately, emerging technologies such as functional genomics and proteomics have uncovered novel candidates that are emerging as potentially useful biomarkers of acute kidney injury (AKI). The most promising of biomarkers in AKI for clinical use include a plasma panel consisting of Neutrophil Gelatinase-Associated Lipocalin (NGAL) and Cystatin C and a urine panel including NGAL, Il-18 and Kidney Injury Molecule 1 (KIM-1). Most of these biomarkers were developed in non-transplant AKI, yet their role in clinical transplantation has to be identified.

Neutrophil Gelatinase-Associated Lipocalin (NGAL) and Kidney Injury Molecule 1 (KIM1) in patients with diabetic nephropathy: a cross-sectional study and the effects of lisinopril

AIMS

Our aim was to evaluate the markers of tubulointerstitial damage, neutrophil gelatinase-associated lipocalin (NGAL) and kidney injury molecule1 (KIM1) in Type 1 diabetic patients with different levels of albuminuria and in control subjects. In addition, the effect of renoprotective treatment on urinary NGAL was evaluated in diabetic nephropathy.

METHODS

This was a cross-sectional study in 58 normoalbuminuric (u-albumin <30 mg/24 h), 45 microalbuminuric (30-300 mg/24 h) and 45 macroalbuminuric (>300 mg/24 h) Type 1 diabetic patients and 55 non-diabetic control subjects. Furthermore, in a second study, urine-NGAL was measured in a randomized cross-over study of 56 Type 1 diabetic patients with diabetic nephropathy treated with lisinopril 20, 40 and 60 mg daily.

RESULTS

  Urine-NGAL levels were [geometric mean (95% CI)]: control subjects 74 (52-104) (pg/mmol creatinine), normoalbuminuric 146 (97-221), microalbuminuric 222 (158-312) and macroalbuminuric group 261 (175-390). Urine-NGAL increased significantly from the normo- to the micro- and further to the macroalbuminuric group (P<0.05). Urine-NGAL was higher in normoalbuminuric vs. control subjects (P<0.01). Plasma-NGAL was significantly higher in the normoalbuminuric and macroalbuminuric groups than in the control group. Urine-KIM1 was higher in all diabetic groups than in the control group (P<0.001), with no difference between diabetic groups. During lisinopril treatment, urine-NGAL was reduced (95% CI) 17% (11-50) (not significant).

CONCLUSIONS

Urine-NGAL and urine-KIM1 (u-KIM1) are elevated in Type1 diabetic patients, with or without albuminuria, indicating tubular damage at an early stage. Urine-NGAL increases significantly with increasing albuminuria. The ACE inhibitor lisinopril reduced urine-NGAL, but this was not statistically significant.