Identification of transcripts associated with renal damage due to ureteral obstruction as candidate urinary biomarkers

Irisin ameliorates UUO-induced renal interstitial fibrosis through TGF-β1/periostin/MMP-2 signaling pathway

Renal fibrosis is the most common pathway in progressive kidney diseases. The unilateral ureteral obstruction (UUO) model is used to induce progressive renal fibrosis. We evaluated the effects of irisin on renal interstitial fibrosis in UUO mice. The GSE121190, GSE36496, GSE42303, and GSE96101 datasets were downloaded from the Gene Expression Omnibus (GEO) database. In total, 656 differentially expressed genes (DEGs) were identified in normal and UUO mouse renal samples. Periostin and matrix metalloproteinase-2 (MMP-2) were selected to evaluate the effect of irisin on renal fibrosis in UUO mice. In UUO mice, irisin ameliorated renal function, decreased the expression of periostin and MMP-2, and attenuated epithelial-mesenchymal transition and extracellular matrix deposition in renal tissues. In HK-2 cells, irisin treatment markedly attenuated TGF-β1-induced expression of periostin and MMP-2. Irisin treatment also inhibited TGF-β1-induced epithelial-mesenchymal transition, extracellular matrix formation, and inflammatory responses. These protective effects of irisin were abolished by the overexpression of periostin and MMP-2. In summary, irisin treatment can improve UUO-induced renal interstitial fibrosis through the TGF-β1/periostin/MMP-2 signaling pathway, suggesting that irisin may be used for the treatment of renal interstitial fibrosis.

The Inhibition of Fibrosis and Inflammation in Obstructive Kidney Injury via the miR-122-5p/SOX2 Axis Using USC-Exos

Background: Fibrosis and inflammation due to ureteropelvic junction obstruction substantially contributes to poor renal function. Urine-derived stem-cell-derived exosomes (USC-Exos) have therapeutic effects through paracrine. Methods: In vitro, the effects of USC-Exos on the biological functions of HK-2 and human umbilical vein endothelial cells were tested. Cell inflammation and fibrosis were induced by transforming growth factor-β1 and interleukin-1β, and their anti-inflammatory and antifibrotic effects were observed after exogenous addition of USC-Exos. Through high-throughput sequencing of microRNA in USC-Exos, the pathways and key microRNAs were selected. Then, the antifibrotic and anti-inflammatory effects of exosomal miR-122-5p and target genes were verified. The role of the miR-122-5p/SOX2 axis in anti-inflammatory and antifibrotic effects was verified. In vivo, a rabbit model of partial unilateral ureteral obstruction (PUUO) was established. Magnetic resonance imaging recorded the volume of the renal pelvis after modeling, and renal tissue was pathologically analyzed. Results: We examined the role of USC-Exos and their miR-122-5p content in obstructive kidney injury. These Exos exhibit antifibrotic and anti-inflammatory activities. SOX2 is the hub gene in PUUO and negatively related to renal function. We confirmed the binding relationship between miR-122-5p and SOX2. The anti-inflammatory and antifibrotic effects of miR-122-5p were inhibited, indicating that miR-122-5p has anti-inflammatory and antifibrotic effects by inhibiting SOX2 expression. In vivo, the PUUO group showed typical obstructive kidney injury after modeling. After USC-Exo treatment, the shape of the renal pelvis shown a remarkable improvement, and inflammation and fibrosis decreased. Conclusions: We confirmed that miR-122-5p from USC-Exos targeting SOX2 is a new molecular target for postoperative recovery treatment of obstructive kidney injury.

The effect of tannic acid on renal renin-angiotensin signaling pathway in a model of unilateral ureteral obstruction in male Wistar rats

The purpose of current study was to elucidate polyphenol tannic acid effect on renal function and activity of the renin-angiotensin system after unilateral ureteral obstruction (UUO). Male Wistar rats were divided into three groups of six randomly: 1) Sham, 2) UUO, and 3) UUO + Tannic acid. Rats in the UUO and UUO + Tannic acid groups experienced unilateral ureteral obstruction. In the Sham group, the abdominal cavity was exposed without UUO induction. In the UUO + Tannic acid group, animals received tannic acid (20 mg/kg) intraperitoneally, 6 and 12 h after clamping the left ureter and 6 and 12 h after the right nephrectomy. Blood samples were taken to measure blood urea nitrogen (BUN) and creatinine levels. Kidney tissue samples were obtained for assessment of oxidative stress, inflammatory indices and the levels of renin-angiotensin system components. Tannic acid administration significantly improved UUO-induced kidney dysfunction (serum BUN: 66.42 ± 14.414 mg/dl, p < 0.05; serum creatinine: 1.67 ± 0.258 mg/dl, p < 0.05), oxidative stress (MDA level: 95.29 ± 37.35 µmol/g tissue, p < 0.05; SOD activity: 59.82 ± 13.41 U/g protein, p < 0.01) and inflammation (renal TNF-α: 57.05 ± 15.653 pg/g tissue, p < 0.05; renal IL-6: 117.015 ± 24.076 pg/g tissue, p < 0.001). The treatment caused a reduction in the amount of renal angiotensinogen, renin and ACE genes expression compared to the UUO group (Angiotensinogen: 8.9 ± onefold, p < 0.05, Renin: 6.5 ± 1.14 fold, p < 0.05, ACE: 4.9 ± 0.64 fold, p < 0.05). Angiotensin II type 1 receptor protein levels decreased in the tannic acid-treated rats in comparison with the UUO group (0.61 ± 0.136, p < 0.05). According to the result of the current study, tannic acid considerably attenuated the complications of unilateral ureteral obstruction through renin-angiotensin system modulation. Trial registration: IR.TUMS.MEDICINE.REC.1400.802.

A systematic review of underlying genetic factors associated with ureteropelvic junction obstruction in stenotic human tissue

OBJECTIVE

Genetic factors are implicated in the development of ureteropelvic junction obstruction (UPJO). The aims of this study were: 1) condense and examine the existing data in studies containing information regarding differential gene expression in tissues from patients with UPJO and 2) investigate associations between genetic markers and their related pathways.

MATERIALS AND METHODS

A systematic review of studies published between January 2000 and September 2021 was conducted using the following databases: Ovid/Medline, PubMed, Wiley Cochrane Central Register of Controlled Trials, Web of Science, and Scopus. Of 249 studies, 10 were included in the final analysis. The search was performed using the terms "ureteropelvic junction obstruction", "genetic", "gene", and "gene expression". Literature pertaining to differential gene expression in UPJO patients as compared to healthy controls was identified. Studies containing gene expression and quantification of molecular data carried out directly on stenotic tissue samples were selected for analysis. Gene network connections and functional analyses were then determined using MetaScape software.

RESULTS

From the ten studies identified for analysis, fifteen genes were noted as differentially expressed. In UPJO patients, nine genes were upregulated (ET1, ACTA2, MCP-1, TGFB1, NFKB1, IL-6, HIF1A, S100A1, SYP) and six were downregulated (ADM, NOS2, EGF, PDGFRA, UCHL1, NGFR). These genes were principally involved in HIF-1 signaling pathway, blood vessel development, positive regulation of signaling receptor activity, and Ras signaling pathway.

CONCLUSIONS

A potential link exists between genes related to hypoxia, excessive fibrous tissue formation, and inflammation in the development of UPJO, and these connections merit more detailed, tissue level investigations in UPJO patients. The outcomes of this systematic review may lay the groundwork for the development of future targeted therapies and novel biomarker detection for treatments, early detection, and possible prediction and prevention of development of UPJO.

Olfactory receptors contribute to progression of kidney fibrosis

Olfactory receptors (ORs) which are mainly known as odor-sensors in the olfactory epithelium are shown to be expressed in several non-sensory tissues. Despite the specified role of some of these receptors in normal physiology of the kidney, little is known about their potential effect in renal disorders. In this study, using the holistic view of systems biology, it was determined that ORs are significantly changed during the progression of kidney fibrosis. For further validation, common differentially expressed ORs resulted from reanalysis of two time-course microarray datasets were selected for experimental evaluation in a validated murine model of unilateral ureteral obstruction (UUO). Transcriptional analysis by real-time quantitative polymerase chain reaction demonstrated considerable changes in the expression pattern of Olfr433, Olfr129, Olfr1393, Olfr161, and Olfr622 during the progression of kidney fibrosis. For localization of these ORs, single-cell RNA-sequencing datasets of normal and UUO mice were reanalyzed. Results showed that Olfr433 is highly expressed in macrophages in day-2 and 7 post-injury in UUO mice and not in normal subgroups. Besides, like previous findings, Olfr1393 was shown to be expressed prominently in the proximal tubular cells of the kidney. In conclusion, our combinatorial temporal approach to the underlying mechanisms of chronic kidney disease highlighted the potential role of ORs in progression of fibrosis. The expression of Olfr433 in the macrophages provides some clue about its relation to molecular mechanisms promoted in the fibrotic kidney. The proposed ORs in this study could be the subject of further functional assessments in the future.

Exploration the potential mechanism of the SIRT1 and its target gene FOXO1/PPARGC1A in uteropelvic junction obstruction

Background

Uteropelvic junction obstruction (UPJO) is a common surgical condition, which refers to the blockage of urine flowing through kidney into proximal upper ureter. However, the underlying mechanism of UPJO is poorly understood, especially the regulated and targeted genes of sirtuin 1 in UPJO.

Methods

We sequenced three renal tissues on the obstructed side of independent children with <20% differential renal function (DRF) and three samples with >40% DRF. Gene expression values were obtained and compared for differentially expressed genes (DEGs). Protein-protein interaction (PPI) analysis was conducted to identify the overlapping proteins of DEGs and Sirtuin 1 (SIRT1). The co-expression genes of overlapped genes were computed using Pearson correlation coefficient. The potential role of SIRT1 gene in UPJO was explored by resequencing 3 microarray data from RNA interference (RNAi) SIRT1 lines of renal tubular epithelial (NRK52E) cells in rat and three control datasets were sequenced again. The DEGs were obtained as parallel. GO/KEGG enrichment analysis and co-expression network were conducted to explore the underlying mechanism, particularly shared pathways or function in GO/KEGG enrichment analysis results.

Results

A total of 427 up-regulated genes and 1,099 down-regulated genes were identified among 3 mRNA-seq of renal tissue on the obstructed side of the independent children with <20% DRF and 3 samples with >40% DRF. According to prediction using the Search Tool for Retrieval of Interacting Genes/Proteins, 2 PPIs, FOXO1 and PPARGC1A, were identified among 2,524 DEGs, predicted as targets of SIRT1. Gene set enrichment analysis (GSEA) of their co-expression genes showed they may co-participate in biological activities including fatty acid degradation, regulation of signal transduction by p53 mediator. Moreover, GSEA results of DEGs was confirmed through RNAi SIRT1 lines of rat renal tubular epithelial (NRK52E) cells.

Conclusions

UPJO may cause abnormal phenotypic changes of renal tubular epithelial cells through SIRT1/FOXO1 mediated protein transport, establishment of protein localization, and intracellular transport. In addition, UPJO is involved in regulation of signal transduction, regulation of intracellular estrogen receptor signaling pathways, and nucleoprotein localization through SIRT1/PPARGC1A-mediated p53 mediators, causing abnormal phenotypic changes in renal tubular epithelial cells.

Sprr2f protects against renal injury by decreasing the level of reactive oxygen species in female mice

Renal injury leads to chronic kidney disease, with which women are not only more likely to be diagnosed than men but have poorer outcomes as well. We have previously shown that expression of small proline-rich region 2f (Sprr2f), a member of the small proline-rich region (Sprr) gene family, is increased several hundredfold after renal injury using a unilateral ureteral obstruction (UUO) mouse model. To better understand the role of Sprr2f in renal injury, we generated a Sprr2f knockout (Sprr2f-KO) mouse model using CRISPR-Cas9 technology. Sprr2f-KO female mice showed greater renal damage after UUO compared with wild-type (Sprr2f-WT) animals, as evidenced by higher hydroxyproline levels and denser collagen staining, indicating a protective role of Sprr2f during renal injury. Gene expression profiling by RNA sequencing identified 162 genes whose expression levels were significantly different between day 0 and day 5 after UUO in Sprr2f-KO mice. Of the 162 genes, 121 genes were upregulated after UUO and enriched with those involved in oxidation-reduction, a phenomenon not observed in Sprr2f-WT animals, suggesting a protective role of Sprr2f in UUO through defense against oxidative damage. Consistently, bilateral ischemia-reperfusion injury resulted in higher serum blood urea nitrogen levels and higher tissue reactive oxygen species in Sprr2f-KO compared with Sprr2f-WT female mice. Moreover, cultured renal epithelial cells from Sprr2f-KO female mice showed lower viability after oxidative damage induced by menadione compared with Sprr2f-WT cells that could be rescued by supplementation with reduced glutathione, suggesting that Sprr2f induction after renal damage acts as a defense against reactive oxygen species.

Profiling histone modifications in the normal mouse kidney and after unilateral ureteric obstruction

Posttranslational modification of nucleosomal histones is a major determinant of chromatin structure and gene activity. In the present study, we hypothesized that unilateral ureteric obstruction (UUO), a widely used model of tubulointerstitial injury, would be associated with a distinct pattern of histone modifications (marks) in the kidney. Mass spectrometry was used to profile 63 different histone marks in normal mouse kidneys and those after 10 days of UUO. A subsequent histochemical analysis further examined examples of specific marks that changed significantly after UUO for which antisera are available. Histone marks were much more widely distributed and abundant in the normal kidney than is usually appreciated. Although aggregate analysis of the mass spectrometry results revealed net differences between control and UUO groups, residue-specific variations were subtle. Of the 16/63 significant changes ( P < 0.05), only 8 changes were quantitatively different by >5%. Nevertheless, we identified several that are not usually examined in the kidney, including marks in the globular domain of core histones (H3:K79), linker histones (H1.4), and histone variants (H3.1:K27 and H3.3:K27). In several cases, there were complementary changes in different marks on the same amino acid. Using H3:K79ME2 as an example, mark enrichment was heterogeneous but largely colocalized with active transcription in a subset of tubular pathology. In conclusion, our study highlights the importance of unbiased screening in examining histone marks. Simultaneous changes in multiple marks on the same amino acid indicate a coordinated histone mark signature. The heterogeneous enrichment of marks, even within the same tubule, highlights the importance of regulatory context.

Early detection of unilateral ureteral obstruction by desorption electrospray ionization mass spectrometry

Desorption electrospray ionization mass spectrometry (DESI-MS) is an emerging analytical tool for rapid in situ assessment of metabolomic profiles on tissue sections without tissue pretreatment or labeling. We applied DESI-MS to identify candidate metabolic biomarkers associated with kidney injury at the early stage. DESI-MS was performed on sections of kidneys from 80 mice over a time course following unilateral ureteral obstruction (UUO) and compared to sham controls. A predictive model of renal damage was constructed using the LASSO (least absolute shrinkage and selection operator) method. Levels of lipid and small metabolites were significantly altered and glycerophospholipids comprised a significant fraction of altered species. These changes correlate with altered expression of lipid metabolic genes, with most genes showing decreased expression. However, rapid upregulation of PG(22:6/22:6) level appeared to be a hitherto unknown feature of the metabolic shift observed in UUO. Using LASSO and SAM (significance analysis of microarrays), we identified a set of well-measured metabolites that accurately predicted UUO-induced renal damage that was detectable by 12 h after UUO, prior to apparent histological changes. Thus, DESI-MS could serve as a useful adjunct to histology in identifying renal damage and demonstrates early and broad changes in membrane associated lipids.

Elevated urinary lipocalin-2, interleukin-6 and monocyte chemoattractant protein-1 levels in children with congenital ureteropelvic junction obstruction

INTRODUCTION

In children with congenital ureteropelvic junction obstruction (UPJO), urinary biomarkers could assist in the diagnosis of renal damage or kidneys at risk for damage. Urinary levels of interleukin-6 (IL6), neutrophil gelatinase-associated lipocalin (LCN2), monocyte chemoattractant protein-1 (MCP1), and transforming growth factor-β1 (TGFB1) proteins have been correlated with renal damage in several contexts. Whether they might be useful non-invasive biomarkers of obstructive nephropathy due to unilateral and bilateral congenital UPJO was tested.

PATIENTS AND METHODS

A cohort study was performed at People's Hospital of Xinjiang Uygur Autonomous Region in China. Bladder urine samples from 17 patients with UPJO were obtained before surgical intervention and from 17 healthy age-matched controls. Levels of IL6, LCN2, MCP1, and TGFB1 were determined by enzyme-linked immunosorbent assay and normalized to urinary creatinine levels.

RESULTS

Levels of urinary LCN2, MCP1, and IL6 were significantly elevated in the urine from individuals with UPJO compared with controls (P = 0.0003, P = 0.0003, and P = 0.0073, respectively). Children with bilateral UPJO (n = 5) showed significantly higher levels of IL6, LCN2, and MCP1 protein in their urine compared with controls or those with unilateral UPJO (n = 12; P = 0.007, P < 0.0001, and P = 0.0002, respectively). Combining LCN2 and MCP1 slightly improved biomarker performance.

DISCUSSION

Urinary biomarkers could be used in obstructed patients to monitor for renal damage and might find particular utility on patients with bilateral UPJO. Monitoring urinary biomarkers and imaging features in untreated patients could provide insights into the natural history of renal damage due to obstruction and will be necessary to test their performance characteristics as biomarkers.

CONCLUSIONS

Urinary levels of LCN2 and MCP1 protein are promising biomarkers monitoring children with UPJO, particularly in those with bilateral disease.