Urinary KIM-1 is not correlated with gestational age among 5-year-old children born prematurely.

Background: Preterm birth is associated with decreased nephron endowment. Currently, there is no reliable non-invasive biomarker to identify or monitor decreased nephron number in at-risk patients. Urinary Kidney Injury Molecule-1 (KIM-1) is a biomarker of acute and chronic renal injury. We measured urinary KIM-1 among a wide array of other potential biomarkers. Methods: We conducted an ambispective cohort study of 5-years-old children born prematurely and healthy controls identified from city schools. Detailed anthropometrics, renal ultrasound dimensions, and biochemical parameters were measured. Urinary KIM-1 was measured using Luminex® technology. Age independent z-scores were calculated and compared. Spearman correlations were used for estimating the association between measures and KIM-1. Results: We enrolled 129 children, 97 (75.2%) born pre-term and 32 (24.8%) healthy controls born at full-term. Pre-term patients had significantly lower weight and body surface area than controls. Pre-term patients and controls did not differ in current age, sex, race, height, blood pressure, urinary sodium, fractional sodium excretion, serum creatinine and estimated GFR. All spearman correlation between KIM-1 and gestational age, renal and serum measurements were weak without statistical significance. Conclusion: In 5-year-old children born prematurely, KIM-1 was not correlated with gestational age. Further prospective studies need to confirm this finding.

(-)-α-Bisabolol as a protective agent against epithelial renal cytotoxicity induced by amphotericin B.

INTRODUCTION: Amphotericin B (AmB), used for systemic fungal infections, has a limited clinical application because of its high nephrotoxicity. Natural antioxidant and anti-inflammatory substances have been widely studied for protection against drug-induced nephrotoxicity. α-Bisabolol (BIS) has demonstrated a nephroprotective effect on both in vitro and in vivo models. AIMS: The aim of this work was to evaluate the effect of BIS against AmB-induced nephrotoxicity in vitro. MATERIAL AND METHODS: LLC-MK2 cells were pre- and post-treated with non-toxic BIS concentrations and/or AmB IC50 (13.97 µM). Cell viability was assessed by MTT [(3-(4,5-dimethylthiazol-2-yl)-2,5-diphenyltetrazolium bromide)] assay. Flow cytometry analyses were used to assess cell death mechanism, production of reactive oxidative stress (ROS) and mitochondrial transmembrane potential. Kidney Injury Molecule-1 (KIM-1) levels were measured via ELISA. KEY FINDINGS: The present work showed that BIS pretreatment (125; 62.5 and 31.25 µM) increased cell viability when compared to the group treated only with AmB IC50. AmB treatment induced both necrosis (7-AAD-labeled cells) and late apoptosis (AnxV-labeled). BIS was able to prevent the occurrence of these events. These effects were associated with a decrease of ROS accumulation, improving transmembrane mitochondrial potential and protecting against tubular cell damage, highlighted by the inhibition of KIM-1 release after BIS treatment. SIGNIFICANCE: BIS presented a potential effect on model of renal cytotoxicity induced by AmB, bringing perspectives for the research of new nephroprotective agents.

Correlation between urinary KIM-1 and kidney protein expression of p-ERK following damage in rats exposed to gentamicin or lead acetate.

Kidney injury molecule-1 (KIM-1) is a membrane receptor upregulated in the proximal tubule cells following various types of kidney injuries. Notably, studies have suggested a correlation between KIM-1 expression and extracellular signal-regulated kinase (ERK) activation. In this study, we aimed to investigate the association between the kidney overexpression pattern of cytoplasmic phosphorylated-ERK (p-ERK) protein and increased urinary KIM-1 levels in rats exposed to gentamicin or lead acetate, both at the end of toxic exposure and after a 4-week recovery period. Although other proteins were evaluated, only kidney overexpression of cytoplasmic p-ERK protein correlated with increased urinary KIM-1 levels. For both toxic substances, the increased urinary KIM-1 levels corresponded with kidney inflammation. Our results suggest that KIM-1 and p-ERK share a common mechanism in kidney injury mediated by both toxic substances that induce proximal tubule damage.

Kidney Injury Molecule-1 in the detection of early kidney injury in dogs with leptospirosis.

Renal damage, a common feature in canine leptospirosis, ranges from a subclinical affection to kidney dysfunction and death. Chances of recovery can be improved by early intervention. However, traditional biomarkers (serum urea and creatinine) have limited relevance for precocity. Kidney Injury Molecule-1 (KIM-1) is a transmembrane protein upregulated in early stages of tubular injury. This study evaluated the use of urinary KIM-1 to detect early renal injury in naturally occurring canine leptospirosis. This exploratory research included 30 dogs divided into two groups: (1) dogs with leptospirosis (n = 25) and (2) healthy dogs (n = 5). Leptospira sp. infection was diagnosed through urine PCR and/or direct bacteriologic culture and/or serology (single MAT titters ≥800). Additionally, stage of infection was further characterized in acute and subacute phases based on the onset of clinical symptoms from 3 to 7 days. Urinary KIM-1 (uKIM-1) concentrations were measured in both groups with a commercial canine ELISA kit. uKIM-1 levels were statistically different (P < 0.01) between the studied groups, especially in non-azotemic dogs (P = 0.0042). The biomarker showed 88 % sensibility to diagnosis of kidney injury at> 1.49 ng/mL cut-off. Urine KIM-1 was negatively correlated with urine specific gravity (USG) but accompanied histopathological evidence of renal degeneration, necrosis and regeneration processes, extending information on kidney health. Measurement of KIM-1 in the urine of canine patients was able to detect naturally occurring acute and subacute leptospirosis accompanied by tubular injury in early non-azotemic infections.

Protective Effect of Quercetin on Renal Tubular Cells and the Involvement with the Renin-Angiotensin-Aldosterone Axis

Abstract Ischemia-reperfusion (I/R) plays an important role in the process of acute kidney injury (AKI) due to the generation of reactive oxygen species (ROS). Substances of natural origin have been studied in the prevention of oxidative damage related to I/R. Quercetin is a flavonoid with antioxidant potential and modulate enzymes, such the inhibition of the Rennin-Angiotensin System (RAS). The aim of this study is to evaluate the nephroprotective effect of quercetin against the I/R and analyze the inhibition of RAS. Rhesus monkey Kidney Epithelial Cells (LLC-MK2 line) were submitted to an in vitro ischemia/reperfusion model. After the reperfusion cells were treated with quercetin, the cell viability was accessed by the MTT (3-(4,5-Dimethylthiazol-2-yl)-2,5-Diphenyltetrazolium Bromide) assay. Tubular cell damage was assessed by the Kidney Injury Molecule-1 (KIM-1) measurement. Oxidative stress was evaluated through Thiobarbituric Acid Reactive Substances (TBARS) and reduced glutathione (GSH). The evaluation of cell death and the mitochondrial depolarization were analyzed by flow cytometry. Quercetin prevents cell death reducing oxidative stress and preventing mitochondrial membrane depolarization. Molecular docking showed that quercetin prevents cell damage better than losartan and lisinopril, inhibitors of RAS. Quercetin has a potential to interact with type 1 angiotensin II receptor (AT1) with greater affinity through the formation of five hydrogen bonds of strong intensity.

Novel renal biomarkers show that creatine supplementation is safe: a double-blind, placebo-controlled randomized clinical trial.

The aim of this study was to evaluate the impact of creatine supplementation (CS) on renal function in young, healthy, and active subjects. We used a randomized, double-blind, placebo-controlled clinical trial as the study design. Thirty-six healthy male university students were recruited and divided into three groups: group placebo, group G3 (3 g/day of CS), and group G5 (5 g/day of CS). To assess renal function, new kidney biomarkers, kidney injury molecule-1 (KIM-1) and monocyte chemoattractant protein-1 (MCP-1), were quantified. Serum albumin, serum creatinine, serum urea, estimated glomerular filtration rate (eGFR), proteinuria, and albuminuria were also measured. All groups were evaluated at two times: prior CS or placebo (pre) and after 35 days on CS or placebo (post). After 35 days of intervention, all characteristics were maintained without significant difference (P > 0.05) between the groups, including serum creatinine, eGFR, and more sensitive kidney biomarker concentrations (KIM-1 and MCP-1). The paired analysis showed that the supplemented groups (G3 and 5G) had increased serum creatinine and decreased eGFR levels (P < 0.05). However, the values were still within the normal reference range. In conclusion, the results of renal function evaluation did not show any difference between the evaluated groups. Increased serum creatinine and decreased eGFR levels in CS groups can be explained by increased creatine stores and metabolism, since creatinine is a by-product of creatine metabolism. These findings indicate that the use of CS at doses of 3 g and 5 g/day for a short period (35 days) is safe and did not impair the kidneys or renal function in young healthy subjects.

Evaluation of emerging biomarkers of renal damage and exposure to aflatoxin-B1 in Mexican indigenous women: a pilot study.

Aflatoxins (AFs) are mycotoxins produced by Aspergillus parasiticus and Aspergillus flavus which frequently contaminate maize. These compounds are considered toxic, especially AFB1 which has been classified as a human carcinogen, due to its relationship with the generation of hepatocellular carcinoma. Studies in vivo, in animal models, prove that chronic consumption of AFB1 has an association with renal adverse effects, but evidence in humans is scarce. Therefore, the main objective of this research was to conduct a pilot study to evaluate the correlation between exposure to AFB1 and early-stage renal damage in indigenous women of San Luis Potosí, Mexico. Exposure to AFB1 was measured through the biomarker AFB1-lysine and renal damage through kidney injury molecule-1 (KIM-1), neutrophil gelatinase-associated lipocalin (NGAL), and cystatin-C (Cys-C). AFB1-Lys was measured by HPLC-FLD. The method was validated with a correlation coefficient of 0.99 and limit of detection and quantification of 3.5 and 4.7 pg mL-1, respectively. Levels of NGAL, KIM-1, and Cys-C were determined (median (P25-P75), 5.96 (3.16-15.91), 0.137 (0.137-0.281), and 18.49 (5.76-29.57) ng mL-1, respectively). Additionally, glomerular filtration rate (GFR) (83.3 (59.8-107.4) mL/min/1.73 m2) and serum creatinine (SCr) (0.88 (0.72-1.22) mg dL-1) were obtained. The median concentrations for AFB1-Lys were 2.08 (1.89-5.8) pg mg-1 of albumin. Statistically significant correlations between AFB1-Lys/KIM-1 (Rho = 0.498, p = 0.007) and AFB1/Cys-C (Rho = 0.431, p = 0.014) were found. Our results indicate that women are exposed to AFB1, due to the fact that the AFB1-Lys biomarker was found in a high percentage of the study population (83%). In addition, the results of exposure to AFB1 show a strong significant correlation between KIM-1 and Cys-C that may indicate the toxic renal effect. These results are alarming because of the high toxicity of this compound and require adequate intervention to reduce AFB1 exposure in these populations.

Evaluation of KIM-1 as an early biomarker of snakebite-induced AKI in mice.

Acute kidney injury (AKI) is one of the most important complications of bothropic poisoning and its early identification remains challenging. The nephrotoxicity of Bothrops insularis venom (BinsV) was previously described by our research group. In this study, we continued to evaluate the effect of BinsV on kidney function in mice and LLC-MK2 proximal tubule cells, evaluating KIM-1 protein as an early AKI biomarker. Male Swiss mice were inoculated with BinsV intramuscularly and observed for 24 h in a metabolic cage model. Urine and blood were collected for biochemical analyses and the kidneys were examined for oxide-reducing balance and submitted to histological analysis. LLC-MK2 cells incubated with BinsV were assessed for cell viability and cell death mechanism by flow cytometry. Histological analysis of the kidneys indicated AKI and the oxide-reducing analyses demonstrated a decreasing in reduced glutathione (GSH) levels and an increasing on Malondialdehyde (MDA) levels. BinsV was cytotoxic to LLC-MK2 and the cytometry analyses suggested necrosis. Within 24 h after the envenomation, urinary creatinine did not increase, but the urinary levels of KIM-1 increased. In conclusion, we found AKI evidence in the kidney tissue and the increase in the KIM-1 levels suggest it can be used as an early AKI biomarker.

Nephroprotective effects of (-)-α-bisabolol against ischemic-reperfusion acute kidney injury.

BACKGROUND: Ischemia/reperfusion (I/R) in kidney is commonly related to acute kidney injury (AKI), essentially through oxidative stress. (-)-α-Bisabolol is a sesquiterpene isolated from the essential oil of a variety of plants, including chamomile, which has important antioxidant activity. STUDY DESIGN: This study intends to evaluate the nephroprotective activity of (-)-α-bisabolol (Bis) in both in vivo and in vitro models of kidney I/R. METHODS: Male Wistar rats were submitted to right nephrectomy, followed by ischemia by clamping of the renal artery in the left kidney for 60min. and 48h of reperfusion. The animals were treated orally with Bis (100mg/kg) or vehicle for 24h after reperfusion, and placed in metabolic cages, to evaluate water consumption, diuresis, urinary osmolality, classic biochemical markers and urinary KIM-1 (kidney injury molecule-1). Additionally, the left kidney was collected for histological evaluation and determination of glutathione (GSH) and Thiobarbituric Acid Reactive Substances (TBARS) levels. Tubular epithelial cells LLC-MK2 were used to assess Bis effect on in vitro I/R, by MTT assay. It was performed the cellular respiration tests by flow cytometry: evaluation of the production of cytoplasmic reactive oxygen species by DCFH-DA assay and mitochondrial transmembrane potential analysis with the dye rhodamine 123. RESULTS: I/R caused alterations in diuresis, water intake, urinary osmolality, plasmatic creatinine, urea and uric acid, creatinine clearance, proteinuria and microalbuminuria. Treatment with Bis ameliorated all of these parameters. Also, KIM-1 level enhanced by I/R was also diminished in groups treated with Bis. The histological examination showed that Bis attenuated the morphological changes caused by I/R, markedly vascular congestion and intratubular deposits of proteinaceous material. Additionally, Bis was able to reduce the changes observed in TBARS and GSH levels in kidney tissue. In in vitro assay, Bis was capable to partially protect the cell lineage against cell damage induced by I/R. CONCLUSION: (-)-α-Bisabolol has a nephroprotective effect in kidney I/R, with antioxidant effect. Moreover, this result seems to be associated to a direct protective effect on tubular epithelia.

Urinary levels of early kidney injury molecules in children with vitamin B12 deficiency. / Niveles de moléculas de detección temprana de daño renal en la orina en niños con deficiencia de vitamina B12.

The aim of this study was to investigate urine early kidney injury molecules, including human kidney injury molecule-1 (KIM-1), liver-type fatty-acid binding protein (L-FABP), N-acetyl-b-D-glucosaminidase A (NAG), and neutrophil gelatinase-associated lipocalin (NGAL) in children with vitamin B12 (cobalamin) deficiency (CD). Twelve children with vitamin B12 deficiency and 20 healthy matched controls were included. Hematologic parameters, serum urea, creatinine (Cr), electrolytes, B12 and folate levels were recorded. Estimated glomerular filtration rate (eGFR) was calculated. Urine protein, electrolytes, andurinary early markers were measured. Patients with CD had significantly higher urine electrolyte/Cr ratios (p <0.05). Significantly higher urinary KIM-1/Cr, L-FABP/Cr, NAG/Cr and NGAL/Cr were found in CD group (p <0.05). Significant negative correlations were found between levels of serum B12 and urinary markers in the patients (p <0.05). Increased urinary kidney injury molecules and electrolytes in children with B12 deficiency suggest a possible subclinical renal dysfunction, which cannot be determined by conventional kidney function tests.

El objetivo de este estudio fue investigar los niveles de moléculas de detección temprana de daño renal en la orina, que incluyen la molécula 1 de lesión renal en humanos (KIM-1), la proteína hepática transportadora de ácidos grasos (L-FABP), el N-acetil-b-D-glucosaminidasa A (NAG) y la lipocalina asociada con la gelatinasa de neutrófilos (NGAL), en niños con deficiencia de vitamina B12 (cobalamina).Seincluyeron 12 niños condeficiencia de vitamina B12 y 20 niños sanos en el grupo de referencia emparejado. Se registraron los parámetros hematológicos, la urea en suero, la creatinina (Cr), los electrolitos, y los niveles de vitamina B12 y folato. Se calculó la tasa de filtración glomerular estimada (TFGe). Se midieronlosnivelesdeproteínas, electrolitos y marcadoresde deteccióntemprana en laorina. Lospacientescon deficiencia de cobalamina tenían un cociente significativamente superior de electrolitos/Cr en la orina (p < 0,05). Se hallaron niveles significativamente superiores de KIM-1/Cr, L-FABP/ Cr, NAG/Cr y N GAL / Cr en la orina en el grupo con deficiencia de cobalamina (p < 0,05). En estos pacientes, también se hallaron correlaciones negativas significativas entre los niveles de vitamina B12 en suero y los marcadores en la orina (p < 0,05). El aumento de los electrolitos y de las moléculas marcadoras de lesión renal en la orina en los niños con deficiencia de vitamina B12 sugiere una posible disfunción renal subclínica, que no puede determinarse mediante las pruebas funcionales renales convencionales.

Environmental exposure to arsenic and chromium in children is associated with kidney injury molecule-1.

Environmental hazards from natural or anthropological sources are widespread, especially in the north-central region of Mexico. Children represent a susceptible population due to their unique routes of exposure and special vulnerabilities. In this study we evaluated the association of exposure to environmental kidney toxicants with kidney injury biomarkers in children living in San Luis Potosi (SLP), Mexico. A cross-sectional study was conducted with 83 children (5-12 years of age) residents of Villa de Reyes, SLP. Exposure to arsenic, cadmium, chromium, fluoride and lead was assessed in urine, blood and drinking water samples. Almost all tap and well water samples had levels of arsenic (81.5%) and fluoride (100%) above the permissible levels recommended by the World Health Organization. Mean urine arsenic (45.6ppb) and chromium (61.7ppb) were higher than the biological exposure index, a reference value in occupational settings. Using multivariate adjusted models, we found a dose-dependent association between kidney injury molecule-1 (KIM-1) across chromium exposure tertiles [(T1: reference, T2: 467pg/mL; T3: 615pg/mL) (p-trend=0.001)]. Chromium upper tertile was also associated with higher urinary miR-200c (500 copies/µl) and miR-423 (189 copies/µL). Arsenic upper tertile was also associated with higher urinary KIM-1 (372pg/mL). Other kidney injury/functional biomarkers such as serum creatinine, glomerular filtration rate, albuminuria, neutrophil gelatinase-associated lipocalin and miR-21 did not show any association with arsenic, chromium or any of the other toxicants evaluated. We conclude that KIM-1 might serve as a sensitive biomarker to screen children for kidney damage induced by environmental toxic agents.

Kidney function in sugarcane cutters in Nicaragua--A longitudinal study of workers at risk of Mesoamerican nephropathy.

BACKGROUND: Chronic kidney disease is common among sugarcane workers in Central America. The main risk factor seems to be repeated high-intensity work in hot environments. Several cross-sectional studies have been performed but few longitudinal studies. OBJECTIVES: The aim of the study was to examine whether kidney function changes over a few months of work during the harvest period. METHODS: A group of male sugarcane cutters in Nicaragua (N=29, aged 17-38 years) was examined with renal biomarkers before and after shift on the first day at the start of harvest, on the sixth day during acclimatization, and then in mid-harvest 9 weeks later. A reference group (N=25, mainly office workers) was examined with the same biomarkers at start of harvest, and then at end of harvest 5 months later. RESULTS: The pre-shift renal function decreased significantly during 9 weeks of work in the cane cutters. Mean serum creatinine increased (20%), mean estimated glomerular filtration rate decreased (9%, 10mL/min), serum urea N (BUN) increased (41%), and mean urinary neutrophil gelatinase-associated lipocalin (NGAL) increased (four times). The cane cutters also developed cross-shift increases in these biomarkers, in particular serum creatinine and BUN, and in urinary uric acid. The longitudinal decrease in eGFR tended to be associated with the cross-shift increase in serum creatinine. CONCLUSIONS: There was a remarkable decrease of glomerular kidney function, after only 9 weeks of harvest. The cross-shift increase in serum creatinine may be caused by dehydration (pre-renal dysfunction), and when repeated on a daily basis this may cause permanently reduced GFR.

Sub-chronic exposure to fluoride impacts the response to a subsequent nephrotoxic treatment with gentamicin.

Fluoride is an important groundwater contaminant, and more than 200 million people are exposed to high fluoride levels in drinking water, the major source of fluoride exposure. Exposure above 2 ppm of fluoride is associated with renal impairment in humans. In rats, moderate levels of fluoride induce kidney injury at early stages in which the glomerular filtration rate (GFR) is not altered. In the present study, we investigated if sub-nephrotoxic stimulus induced by fluoride might impact the response to a subsequent nephrotoxic treatment with gentamicin. Male Wistar rats (~21 days) were exposed to 0, 15 or 50 ppm of fluoride through drinking water during 40 days. Afer that, rats were co-exposed to gentamicin (40 mg kg(-1) day(-1), 7 days). Gentamicin induced a marked decrease in the GFR and an increase in urinary levels as well as the protein and mRNA expression of biomarkers of early kidney injury, such as Kim-1. Interestingly, gentamicin nephrotoxicity was less pronounced in groups previously exposed to fluoride than in the group only treated with gentamicin. Fluoride induced Hsp72, a cytoprotective molecule, which might have improved the response against gentamicin. Moreover, fluoride decreased the expression of megalin, a molecule necessary for internalization of gentamicin into the proximal tubule, potentially reducing gentamicin accumulation. The present results suggest that fluoride reduced gentamicin-induced nephrotoxicity by inducing a compensatory response carried out by Hsp72 and by decreasing gentamicin accumulation. These findings should not be interpreted to suggest that fluoride is a protective agent as megalin deficiency could lead to serious adverse effects on the kidney physiology.