Role of urinary biomarkers in the diagnosis of congenital upper urinary tract obstruction

Manganese induces podocyte injury through regulating MTDH/ALKBH5/NLRP10 axis: Combined analysis at epidemiology and molecular biology levels

Manganese (Mn) is an essential micronutrient required for various biological processes but excess exposure to Mn can cause neurotoxicity. However, there are few reports regarding the toxicity effect of Mn on the kidney as well as the underlying molecule mechanism. Herein, in vivo experiments were adopted to assess the toxicity effects associated with Mn, and found that chronic Mn treatment induced the injury of glomerular podocytes but not renal tubule in rats. Genome-wide CRISPR/Cas9 knockout screen was then employed to explore the biotargets of the toxic effect of Mn on podocytes. Through functional analyses of the enriched candidate genes, NLRP10 was found to be significantly up-regulated and mediated Mn-induced podocyte apoptosis. Further mechanism investigation revealed that NLRP10 expression was regulated by demethylase AlkB homolog 5 (ALKBH5) in an m6A-dependent fashion upon Mn treatment. Moreover, Mn could directly bind to Metadherin (MTDH) and promoted its combination with ALKBH5 to promote NLRP10 expression and cell apoptosis. Finally, logistic regressions, restricted cubic spline regressions and uniform cubic B-spline were used to investigate the association between Mn exposure and the risk of chronic kidney disease (CKD). A U-shaped nonlinear relationship between CKD risk and plasma Mn level, and a positive linear relationship between CKD risk and urinary Mn levels was found in our case-control study. To sum up, our findings illustrated that m6A-dependent NLRP10 regulation is indispensable for podocyte apoptosis and nephrotoxicity induced by Mn, providing fresh insight into understanding the health risk of Mn and a novel target for preventing renal injury in Mn-intoxicated patients.

The preventive effect of Gastrodia elata Blume extract on vancomycin-induced acute kidney injury in rats

BACKGROUND

Gastrodia elata Blume (GEB), a traditional medicinal herb, has been reported to have pharmacological effect including protection against liver, neuron and kidney toxicity. However, explanation of its underlying mechanisms remains a great challenge. This study investigated the protective effects of GEB extract on vancomycin (VAN)-induced nephrotoxicity in rats and underlying mechanisms with emphasis on the anti-oxidative stress, anti-inflammation and anti-apoptosis. The male Sprague-Dawley rats were randomly divided three groups: control (CON) group, VAN group and GEB group with duration of 14 days.

RESULTS

The kidney weight and the serum levels of blood urea nitrogen and creatinine in the GEB group were lower than the VAN group. Histological analysis using hematoxylin & eosin and periodic acid Schiff staining revealed pathological changes of the VAN group. Immunohistochemical analysis revealed that the expression levels of N-acetyl-D-glucosaminidase, myeloperoxidase and tumor necrosis factor-alpha in the GEB group were decreased when compared with the VAN group. The number of terminal deoxynucleotidyl transferase-mediated dUTP nick end labeling-positive cells, phosphohistone and malondialdehyde levels were lower in the GEB group than VAN group. The levels of total glutathione in the GEB group were higher than the VAN group.

CONCLUSIONS

The findings of this study suggested that GEB extract prevents VAN-induced renal tissue damage through anti-oxidation, anti-inflammation and anti-apoptosis.

Biomarkers of high salt intake

High salt intake is associated with hypertension, which is a leading modifiable risk factor for cardiovascular disease (CVD) and chronic kidney disease (CKD). International Guidelines recommend a large reduction in the consumption of sodium to reduce blood pressure, organ damage, and mortality. In its early stages, the symptoms of CKD are generally not apparent. CKD proceeds in a "silent" manner, necessitating the need for urinary biomarkers to detect kidney damage at an early stage. Since traditional renal biomarkers, such as serum creatinine, are not sufficiently sensitive, difficulties are associated with detecting kidney damage induced by a high salt intake, particularly in normotensive individuals. Several new biomarkers for renal tubular damage, such as neutrophil gelatinase-associated lipocalin (NGAL), kidney injury molecule-1 (KIM-1), vanin-1, liver-type fatty acid-binding protein (L-FABP), and monocyte chemotactic protein-1 (MCP-1), have recently been identified. However, few studies have investigated early biomarkers for CKD progression associated with a high salt diet. This chapter provides insights into novel biomarkers for CKD in normo- and hypertensive individuals with a high salt intake. Recent studies using spontaneously hypertensive rats (SHR) and normotensive Wistar Kyoto rats (WKY) fed a high salt diet identified urinary vanin-1 and NGAL as early biomarkers for renal tubular damage in SHR and WKY, whereas urinary KIM-1 was a useful biomarker for salt-induced renal injury in SHR only. Clinical studies are needed to confirm these findings.

Exosomal proteomic analysis reveals changes in the urinary proteome of rats with unilateral ureteral obstruction

Congenital urinary tract obstruction (UTO) is a commonly noted disorder with the potential to cause permanent loss of renal function. Due to the possibility of spontaneous resolution, postnatal management strategies require lengthy and invasive surveillance methods to monitor the status of renal function and severity of obstruction. Here, a quantitative proteome analysis of urinary exosomes from weanling rats with surgically introduced UTO identifies a number of candidate biomarkers with the potential to improve diagnostic and prognostic methods for this disease. Using gel-assisted digestion coupled to liquid chromatography/tandem mass spectrometry (LC–MS/MS), 318 proteins were identified. Relative protein quantitation by spectral counting showed 190 proteins with significant changes in abundance due to either partial or complete obstruction. Numerous proteins identified here have been shown to be similarly altered in abundance in other renal diseases that cause tubule apoptosis and interstitial fibrosis. Extrapolating the role of the proteins showing quantifiable changes in abundance here from other forms of renal disease suggests they have potential for clinical applicability as biomarkers of congenital UTO. Included in the list of identified proteins are markers of apoptosis, oxidative stress, fibrosis, inflammation, and tubular cell damage, which are commonly associated with UTO. This study therefore provides a number of candidate biomarkers that, following validation in children experiencing UTO, have the potential to improve postnatal management of this disease.

The Role of Urinary N-acetyl Beta-D-glucosaminidase in Children with Urological Problems

OBJECTIVES

To assess urinary NAG/ urinary creatinine (NAG/ Cr) ratio in patients with urological abnormalities (normal and abnormal ultrasonography) and compare it with normal healthy children.

METHODS

A prospective study was conducted from November 2012 to April 2013. Urine samples were collected from 70 patients with various urological abnormalities, and from 40 healthy control groups, their age range (1 month-13 years). Children who were admitted to Emergency Pediatric department, Children Welfare Teaching Hospital / Medical City Complex, Baghdad, Iraq. The Glomerular filtration rate was in normal range in all of them. Urine samples were tested for NAG by (ELISA, Cusabio, China) while, both Serum creatinine (S-Cr) and urine creatinine (U-Cr) were estimated by Jaffe's kinetic method.

RESULTS

In this study 29% of the patients had normal ultrasonography and 72% abnormal ultrasonography. The current results revealed that NAG/creatinine index was significantly higher in all patients with (vesicoureteral reflux, hydronephrosis and pyelonephritis) in comparison with cystitis.

CONCLUSION

The assessment of urinary NAG could be considered as a useful marker in prediction of the (vesicoureteral reflux, hydronephrosis) .Urinary NAG is elevated in children with pyelonephritis and it can be considered as a further criterion in the diagnosis of upper urinary tract infection.

Association of urinary transforming growth factor-β1 with the ureteropelvic junction obstruction

BACKGROUND

We aimed to compare the level of urinary transforming growth factor-beta 1 (TGF-β1) in children with ureteropelvic junction obstruction (UPJO) with the normal peers.

MATERIALS AND METHODS

In this case-control study, we enrolled children with UPJO and matched normal peers. Sterile urine was collected from the subjects and urinary TGF-β1 was measured by ELISA method. Also, degree of the UPJO and the magnitude of the renal injury were assessed by ultrasonography and measuring glomerular filtration rate (GFR), respectively. Study variables were then compared between the study groups regarding the level of urinary TGF-β1.

RESULTS

A total of 25 children with UPJO (age = 7.4 ± 4.5 years; male = 16) were compared with 25 healthy peers (age = 6.8 ± 5.6 years; male = 16). Mean GFR in the UPJO and the control group were 112.4 ± 10.1 and 123.29 ± 4.4, respectively. Mean urinary TGF-β1 in the UPJO group was 87.1 ± 12.6 pg/ml vs 30.5 ± 14.5 pg/ml in the control group. The level of urinary TGF-β1 was significantly associated with the degree of TGF-β1 and patients with grade IV hydronephrosis had the highest level of urinary TGF-β (P = 0.0001).

CONCLUSION

Based on our findings, biomarkers such as TGF-β1 can successfully be used for confirming UPJO. However, further studies are needed to determine the proper cut point for diagnosis confirmation.

Hydronephrotic urine in the obstructed kidney promotes urothelial carcinoma cell proliferation, migration, invasion through the activation of mTORC2-AKT and ERK signaling pathways

Obstructive nephropathy is the most common presentation of urothelial carcinoma. The role of the urine in the obstructed kidney namely "hydronephrotic urine" in urothelial carcinoma has not been extensively explored. This study aims to evaluate whether hydronephrotic urine in the obstructed kidney could promote urothelial carcinoma. The hydronephrotic urine was collected from the obstructed kidneys of Sprague-Dawley rats induced by different periods of unilateral ureteral obstruction (UUO). By the inhibition of LY294002 and PD184352, we confirm that hydronephrotic urine promotes urothelial carcinoma cell (T24) and immortalized normal urothelial cells (E6) proliferation, migration and invasion in a dose-dependent manner through the activation of the mTORC2-AKT and ERK signaling pathways. Hydronephrotic urine also increases the expression of cyclin-D2, cyclin-B and CDK2. It also decreases the expression of p27 and p21 in both urothelial carcinoma cells and normal urothelial cells. By the protein array study, we demonstrate that many growth factors which promote tumor cell survival and metastasis are over-expressed in a time-dependent manner in the hydronephrotic urine, including beta-FGF, IFN-γ, PDGF-BB, PIGF, TGF-β, VEGF-A, VEGF-D and EGF. These results suggest that hydronephrotic urine promotes normal and malignant urothelial cells proliferation, migration and invasion, through the activation of the mTORC2-AKT and ERK signaling pathways. Further investigation using live animal models of tumor growth may be needed to clarify aspects of these statements.

Hydronephrosis due to pelviureteric junction narrowing: Utility of urinary enzymes to predict the need for surgical management and follow-up

AIM

To study the role of urinary enzymes N-acetyl-β-glucosaminidase (NAG), alkaline phosphatase (AKP) and gamma glutamyl transferase (GGT) in the diagnosis and follow-up of patients with suspected pelviureteric junction obstruction (PUJO).

MATERIALS AND METHODS

A total of 70 patients, 29 managed conservatively (group A) and 41 managed by pyeloplasty (group B), were studied prospectively. A serial measurement of urinary enzymes NAG, AKP and GGT level was performed in both the groups. The mean levels of these urinary enzymes were compared between the two groups and among the patients of the same group at presentation as well as during follow-up.

RESULTS

There was a significant fall in the mean AKP level in patients managed conservatively at 8 months of follow-up. Similarly, in the operated group, there was a significant fall in the AKP levels at both 3 months and 8 months of follow-up. The mean level of GGT also showed a significant fall after 3 months of surgery but did not show further significant change at 8 months after surgery. The mean levels of NAG and GGT in the conservatively managed group were significantly low compared with that of patients requiring pyeloplasty at presentation as well as in the follow-up. The mean level of AKP was significantly low in the conservatively managed group when compared with the patients requiring surgery, but did not differ significantly in both the follow-ups after surgery.

CONCLUSIONS

The level of urinary enzymes NAG, AKP and GGT are significantly high in the patients with hydronephrosis (HDN) requiring pyeloplasty when compared with the patients managed conservatively. The level of AKP significantly falls after pyeloplasty in the patients of HDN due to PUJO. There is a negative correlation with the preoperative level of enzyme NAG with split renal function in the patients of HDN requiring pyeloplasty.

Obstructive renal injury: from fluid mechanics to molecular cell biology

Urinary tract obstruction is a frequent cause of renal impairment. The physiopathology of obstructive nephropathy has long been viewed as a mere mechanical problem. However, recent advances in cell and systems biology have disclosed a complex physiopathology involving a high number of molecular mediators of injury that lead to cellular processes of apoptotic cell death, cell injury leading to inflammation and resultant fibrosis. Functional studies in animal models of ureteral obstruction using a variety of techniques that include genetically modified animals have disclosed an important role for the renin-angiotensin system, transforming growth factor-β1 (TGF-β1) and other mediators of inflammation in this process. In addition, high throughput techniques such as proteomics and transcriptomics have identified potential biomarkers that may guide clinical decision-making.