Tubular and Glomerular Biomarkers of Acute Kidney Injury in Newborns

Nanoselenium attenuates renal ischemia-reperfusion injury in rats

Using selenium (Se) nanoparticles has received attention in recent years because of their therapeutic benefits due to their anticancer, antioxidant, anti-inflammatory, and anti-diabetic effects. This research was conducted to evaluate the possible protective impact of nano-Se on renal unilateral ischemia/reperfusion injury (uIRI) in adult male Wistar rats. Using clamping of the left renal pedicle within 45 min uIRI was induced. The animals were randomly divided into nine groups of control, nano-Se (0.25, 0.5, and 1 mg/kg bw/day) alone, uIRI control, and uIRI rats administrated with nano-Se. At 30 days after treatment, the animals were sacrificed to be assessed biochemically and histopathologically. Nano-Se in uIRI groups have significantly decreased serum creatinine, urea levels, renal histological damage, and increased antioxidant status. Also, our findings demonstrated that the administration of nano-Se caused a significant decrease in the immunoreactivity level of the epidermal growth factor (EGF) and EGFR expression (EGF receptor) in the renal tissue of the uIRI rats. Therefore, nano-Se possesses renoprotective effects, and this effect might be attributable to its antioxidant and free radical scavenger effects. These renoprotective effects may depend on the decreased EGF immunoreactivity level and EGFR expression in the kidney tissue and improve the structure of the kidney tissue. Thus, our research provided biochemical and histological data supporting the potential clinical use of nano-Se for the treatment of certain kidney disorders.

The Urinary Concentrations of Neutrophil Gelatinase-Associated Lipocalin, Cystatin C and Osteopontin in the Healthy Term and Stable Preterm Neonates: A Pilot Study

BACKGROUND

In neonates, the assessment of kidney function with serum creatinine is limited; therefore, more effective biomarkers are needed.

AIM

The study aimed at analyzing the concentrations of renal biomarkers (osteopontin, cystatin C, and NGAL) in neonates.

MATERIAL AND METHODS

The study included 80 term and 20 preterm neonates aged 28-33 weeks of gestation. Biomarkers were measured in urine. Term neonates' urine was collected on the 1st day of life. Preterm neonates' urine was collected on the 1st, 8th, 15th, 22nd day of life. Biomarkers' concentrations were normalized to urinary creatinine (cr.) and presented as urinary biomarker/cr. ratios.

RESULTS

Median values of biomarker/creatine ratios in term and preterm neonates were the following: cystatin C/cr.: 7.26 and 439.49; osteopontin/cr.: 135.86 and 1633.37; NGAL/cr. in girls: 212.14 and 256.93; and NGAL/cr. in boys 27.123 and 65.29 ng/mg cr. In preterm neonates the cystatin C/cr. ratio was higher on the 1st than on the 8th day. The osteopontin/cr. ratio did not differ between the days. The NGAL/cr. ratio in girls was higher on the 8th than on the 22nd day, and in boys, the lowest was on the 22nd day.

CONCLUSIONS

Prematurity in stable, Caucasian neonates might cause higher osteopontin and cystatin C excretion, but not NGAL. The excretion of NGAL and cystatin C, but not osteopontin, may change during first weeks of premature neonate's life.

Effect of Selenium Nanoparticles and/or Bee Venom against STZ-Induced Diabetic Cardiomyopathy and Nephropathy

The main purpose of our study was to examine the role of selenium nanoparticles (SeNPs) and/or bee venom (BV) in ameliorating diabetic cardiomyopathy (DCM) and nephropathy (DN) at the biochemical, histopathological and molecular levels. Fifty male albino rats were used in this experiment, divided into five groups: control, Streptozocin (STZ) diabetic, STZ-diabetic treated with SeNPs, STZ-diabetic treated with BV, and STZ-diabetic treated with SeNPs and BV. Biochemically, STZ injection resulted in a significant increase in serum glucose, BUN, creatinine, CRP, CK-MB, AST, LDH and cardiac troponins with a significant decrease in the serum insulin and albumin concentrations. Histopathologically, STZ injection resulted in diabetes, as revealed by glomerulonephritis, perivascular hemorrhage, inflammatory cell infiltrations and fibrosis, with widening of interstitial spaces of cardiomyocytes, loss of muscle cells continuity and some hyaline degeneration. At the molecular levels, the expression levels of miRNA 328, miRNA-21, TGFβ1, TGFβ1R, JAK1, STST-3, SMAD-1 and NFκβ genes were significantly up-regulated, whereas the expression levels of SMAD-7 were significantly down-regulated. It is concluded that SeNPs and/or BV administration ameliorates the deleterious effects resulting from STZ administration through improving the biochemical, histopathological and molecular effects, suggesting their protective role against the long-term diabetic complications of DCM and DN.

Gestational age, sex, and time affect urine biomarker concentrations in extremely low gestational age neonates

BACKGROUND

Our understanding of the normative concentrations of urine biomarkers in premature neonates is limited.

METHODS

We evaluated urine from 750 extremely low gestational age (GA) neonates without severe acute kidney injury (AKI) to determine how GA affects ten different urine biomarkers at birth and over the first 30 postnatal days. Then, we investigated if the urine biomarkers changed over time at 27, 30, and 34 weeks postmenstrual age (PMA). Next, we evaluated the impact of sex on urine biomarker concentrations at birth and over time. Finally, we evaluated if urine biomarkers were impacted by treatment with erythropoietin (Epo).

RESULTS

We found that all ten biomarker concentrations differ at birth by GA and that some urine biomarker concentrations increase, while others decrease over time. At 27 weeks PMA, 7/10 urine biomarkers differed by GA. By 30 weeks PMA, 5/10 differed, and by 34 weeks PMA, only osteopontin differed by GA. About half of the biomarker concentrations differed by sex, and 4/10 showed different rates of change over time between males vs. females. We found no differences in urine biomarkers by treatment group.

CONCLUSIONS

The temporal patterns, GA, and sex differences need to be considered in urine AKI biomarker analyses.

IMPACT

Urine biomarker concentrations differ by GA at birth. Some urine biomarkers increase, while others decrease, over the first 30 postnatal days. Most urine biomarkers differ by GA at 27 weeks PMA, but are similar by 34 weeks PMA. Some urine biomarkers vary by sex in premature neonates. Urine biomarkers did not differ between neonates randomized to placebo vs. Epo.

Impact of nephrotoxic drugs on urinary biomarkers of renal function in very preterm infants

BACKGROUND

Following preterm birth, the immature kidney is exposed to several harmful conditions, with an increased risk of renal impairment. We aimed to assess urinary biomarkers of renal function in very preterm infants during early nephrotoxic treatments.

METHODS

Infants ≤32 weeks' gestation and ≤1500 g were enrolled in this observational prospective study. Urine samples were collected on day 1(T1), 2-4(T2), 5-7(T3), 8-10(T4), 11-13(T5). The following urinary biomarkers were determined: osteopontin (uOPN), epidermal growth factor (uEGF), neutrophil gelatinase-associated lipocalin (uNGAL), cystatin C (uCysC). The infants were grouped according to their exposure to amikacin or ibuprofen during the study period and a between-group comparison of urinary biomarkers at each time point was performed.

RESULTS

Thirty-six infants were included. Urinary CysC, uOPN, and uNGAL rose significantly during ibuprofen or amikacin treatment, while no difference was observed for uEGF. After adjustment for possible influencing factors, amikacin administration was associated with higher uCysC at T1 (p = 0.007) and T2 (p = 0.016), whereas ibuprofen increased uOPN (p = 0.001) and uNGAL concentration (p = 0.009) at T3.

CONCLUSION

Nephrotoxic therapies induce molecule-specific change patterns of renal function biomarkers in treated preterm infants. Serial assessments of these biomarkers may aid to identify neonates at risk of renal impairment and to develop tailored therapeutic approaches.

IMPACT

Despite the wide use of nephrotoxic therapies in neonatal settings, little is known on their effect on renal function biomarkers in preterm infants. This study describes molecule-specific change patterns of urinary biomarkers during ibuprofen and amikacin administration, suggesting underlying pathophysiological effects on renal function. Given their low analytical costs and non-invasive collection, the urinary biomarkers investigated in this study represent a promising strategy for serial monitoring of renal function in at-risk neonates and may aid the early detection of renal function impairment at different kidney levels during nephrotoxic treatments.

Toxicological effects of thimerosal on rat kidney: a histological and biochemical study

Thimerosal is an organomercurial compound, which is used in the preparation of intramuscular immunoglobulin, antivenoms, tattoo inks, skin test antigens, nasal products, ophthalmic drops, and vaccines as a preservative. In most of animal species and humans, the kidney is one of the main sites for mercurial compounds deposition and target organs for toxicity. So, the current research was intended to assess the thimerosal induced nephrotoxicity in male rats. Twenty-four adult male albino rats were categorized into four groups. The first group was a control group. Rats of Group-II, Group-III, and Group-IV were administered with 0.5µg/kg, 10µg/kg, and 50µg/kg of thimerosal once a day, respectively. Thimerosal administration significantly decreased the activities of catalase (CAT), superoxide dismutase (SOD), peroxidase (POD), glutathione reductase (GR), glutathione (GSH), and protein content while increased the thiobarbituric acid reactive substances (TBARS) and hydrogen peroxide (H2O2) levels dose-dependently. Blood urea nitrogen (BUN), creatinine, urobilinogen, urinary proteins, kidney injury molecule-1 (KIM-1), and neutrophil gelatinase-associated lipocalin (NGAL) levels were substantially increased. In contrast, urinary albumin and creatinine clearance was reduced dose-dependently in thimerosal treated groups. The results demonstrated that thimerosal significantly increased the inflammation indicators including nuclear factor kappaB (NF-κB), tumor necrosis factor-α (TNF-α), Interleukin-1β (IL-1β), Interleukin-6 (IL-6) levels and cyclooxygenase-2 (COX-2) activities, DNA and histopathological damages dose-dependently. So, the present findings ascertained that thimerosal exerted nephrotoxicity in male albino rats.

Reciprocal assessment of urinary beta-2-microglobulin and BUN levels in renal dysfunction of neonates with birth asphyxia

OBJECTIVE

Asphyxia at birth is one of the major causes of morbidity and mortality in all neonates due to various organ dysfunctions, for example, kidneys. Recent advances in this area have suggested new urinary proteins for the assessment of renal damage, including beta-2 microglobulin (β2-MG). The aim of this study was to investigate the changes of urinary β2-MG in asphyxiated neonates and to evaluate the value of combined detection of multiple biomarkers in the early diagnosis of acute kidney injury (AKI) in asphyxiated neonates.

STUDY DESIGN

This case-control study was performed on 84 term neonates in two control and case groups who were hospitalized at the neonatal intensive care unit. Using the Sarnat scoring system, the asphyxiated neonates were neurologically divided. Renal function tests and urinary β2-MG (uβ2-MG) levels of participants who registered based on inclusion criteria were measured. The data analyzed using descriptive and inferential statistical tests. The diagnostic value of the biomarker was determined using receiver operating characteristic (ROC) curves.

RESULTS

This study showed that uβ2-MG was not a statistically significant difference in both asphyxiated neonates with AKI and non-AKI (p = .085). Whereas, uβ2-MG levels were statistically significant in neurological grading of asphyxiated infants to two groups (p = .013). A new predictor, uβ2-MG and blood urea nitrogen (BUN); named BB1, was substituted as the diagnostic value in neonates with asphyxia with an area under the receiver operating characteristic curve (AUC) (95% CI) of 0.88 (0.76-1.0). This AUC was significantly greater than the value for uβ2-MG associated with AKI (p = .003).

CONCLUSION

Our findings showed that mutual detection of uβ2-MG levels with BUN should be an early indicator for the diagnosis of renal injury with greater specificity and improved prognostic accuracy after neonatal asphyxia.

Is Urinary Netrin-1 a Good Marker of Tubular Damage in Preterm Newborns?

There is a lack of a good marker for early kidney injury in premature newborns. In recent publications, netrin-1 seems to be a promising biomarker of kidney damage in different pathological states. The study aimed to measure the urinary level of netrin-1 depending on gestational age. A prospective study involved 88 newborns (I-60 premature newborns, II-28 healthy term newborns). Additionally, premature babies were divided for 2 groups: IA-28 babies born between 30–34 weeks of gestation and IB-32 born at 35–36 weeks. The median urinary concentration of netrin-1 was: IA-(median, Q1–Q3) 63.65 (56.57–79.92) pg/dL, IB-61.90 (58.84–67.17) pg/dL, and II-60.37 (53.77–68.75) pg/dL, respectively. However urinary netrin-1 normalized by urinary concentration of creatinine were IA-547.9 (360.2–687.5) ng/mg cr., IB-163.64 (119.15–295.96) ng/mg cr., and II-81.37 (56.84–138.58) ng/mg cr., respectively and differ significantly between the examined groups (p = 0.00). The netrin-1/creatinine ratio is increased in premature babies. Further studies examining the potential factors influencing kidney function are necessary to confirm its potential value in the diagnosis of subclinical kidney damage in premature newborns.