Unilateral Ureteral Ligation Research Articles

Inhibition of PKC-δ retards kidney fibrosis via inhibiting cGAS-STING signaling pathway in mice

Kidney fibrosis is considered to be the ultimate aggregation pathway of chronic kidney disease (CKD), but its underlying mechanism remains elusive. Protein kinase C-delta (PKC-δ) plays critical roles in the control of growth, differentiation, and apoptosis. In this study, we found that PKC-δ was highly upregulated in human biopsy samples and mouse kidneys with fibrosis. Rottlerin, a PKC-δ inhibitor, alleviated unilateral ureteral ligation (UUO)-induced kidney fibrosis, inflammation, VDAC1 expression, and cGAS-STING signaling pathway activation. Adeno-associated virus 9 (AAV9)-mediated VDAC1 silencing or VBIT-12, a VDAC1 inhibitor, attenuated renal injury, inflammation, and activation of cGAS-STING signaling pathway in UUO mouse model. Genetic and pharmacologic inhibition of STING relieved renal fibrosis and inflammation in UUO mice. In vitro, hypoxia resulted in PKC-δ phosphorylation, VDAC1 oligomerization, and activation of cGAS-STING signaling pathway in HK-2 cells. Inhibition of PKC-δ, VDAC1 or STING alleviated hypoxia-induced fibrotic and inflammatory responses in HK-2 cells, respectively. Mechanistically, PKC-δ activation induced mitochondrial membrane VDAC1 oligomerization via direct binding VDAC1, followed by the mitochondrial DNA (mtDNA) release into the cytoplasm, and subsequent activated cGAS-STING signaling pathway, which contributed to the inflammation leading to fibrosis. In conclusion, this study has indicated for the first time that PKC-δ is an important regulator in kidney fibrosis by promoting cGAS-STING signaling pathway which mediated by VDAC1. PKC-δ may be useful for treating renal fibrosis and subsequent CKD.

Study on the mechanism of hirudin multi target delaying renal function decline in chronic kidney disease based on the “gut-kidney axis” theory

The disorder of the “gut-kidney axis” exacerbates renal function decline in chronic kidney disease (CKD), and current CKD therapy is insufficient to address this issue. Hirudin has a palliative effect on the decline of renal function. However, whether hirudin can delay CKD by regulating the “intestinal renal axis” disorder remains unclear. Unilateral ureteral ligation (UUO) induced CKD rat model, and the rats were treated with bifidobacterium and hirudin for 36 days. After 14 and 36 days of modeling, kidney and colon tissues were collected for pathology, western blot (WB) assay, and quantitative real-time PCR (qPCR) detection. Serum samples were collected for renal function testing. Fecal samples were used for 16S rRNA sequencing and research on fecal bacterial transplantation. Lipopolysaccharide combine with adenosine 5’-triphosphate (LPS + ATP)-induced intestinal epithelial cell injury was treated with a nod-like receptor pyrin domain-associated protein 3 (NLRP3) inhibitor and hirudin. Protein expression was detected using WB and qPCR. The kidneys and colons of the CKD rats exhibited varying degrees of lesions. Creatinine (CRE), blood urea nitrogen (BUN), N-acetyl-β-D-glucosidase (NAG) enzyme, and serum uremic toxins were elevated. The expression of claudin-1 and occludin was decreased, NLRP3 inflammatory-related proteins were increased, and the gut microbiota was disrupted. These pathological changes were more pronounced after 36 days of modeling. Meanwhile, high-dose hirudin treatment significantly improved these lesions and restored the intestinal flora to homeostasis in CKD rats. In vitro, hirudin demonstrated comparable effects to NLRP3 inhibitors by upregulating claudin-1 and occludin expression, and downregulating NLRP3 inflammatory-related proteins expression. The dysbiosis of the gut microbiota and impaired intestinal epithelial barrier function in CKD are associated with renal dysfunction in CKD. Hirudin delays the progression of CKD by regulating the disorder of the “gut-kidney axis” and inhibiting the activation of the NLRP3-ASC-caspase-1 pathway.

Inducible deletion of microRNA activity in kidney mesenchymal cells exacerbates renal fibrosis

MicroRNAs (miRNAs) are sequence-specific inhibitors of post-transcriptional gene expression. However, the physiological functions of these non-coding RNAs in renal interstitial mesenchymal cells remain unclear. To conclusively evaluate the role of miRNAs, we generated conditional knockout (cKO) mice with platelet-derived growth factor receptor-β (PDGFR-β)-specific inactivation of the key miRNA pathway gene Dicer. The cKO mice were subjected to unilateral ureteral ligation, and renal interstitial fibrosis was quantitatively evaluated using real-time polymerase chain reaction and immunofluorescence staining. Compared with control mice, cKO mice had exacerbated interstitial fibrosis exhibited by immunofluorescence staining and mRNA expression of PDGFR-β. A microarray analysis showed decreased expressions of miR-9-5p, miR-344g-3p, and miR-7074-3p in cKO mice compared with those in control mice, suggesting an association with the increased expression of PDGFR-β. An analysis of the signaling pathways showed that the major transcriptional changes in cKO mice were related to smooth muscle cell differentiation, regulation of DNA metabolic processes and the actin cytoskeleton, positive regulation of fibroblast proliferation and Ras protein signal transduction, and focal adhesion-PI3K/Akt/mTOR signaling pathways. Depletion of Dicer in mesenchymal cells may downregulate the signaling pathway related to miR-9-5p, miR-344g-3p, and miR-7074-3p, which can lead to the progression of chronic kidney disease. These findings highlight the possibility for future diagnostic or therapeutic developments for renal fibrosis using miR-9-5p, miR-344g-3p, and miR-7074-3p.

Network Pharmacology Analysis and Machine-Learning Models Confirmed the Ability of YiShen HuoXue Decoction to Alleviate Renal Fibrosis by Inhibiting Pyroptosis.

YiShen HuoXue decoction (YSHXD) is a formulation that has been used clinically for the treatment of renal fibrosis (RF) for many years. We aimed to clarify therapeutic effects of YSHXD against RF and potential pharmacological mechanisms. We used network pharmacology analysis and machine-learning to screen the core components and core targets of YSHXD against RF, followed by molecular docking and molecular dynamics simulations to confirm the reliability of the results. Finally, we validated the network pharmacology analysis experimentally in HK-2 cells and a rat model of RF established by unilateral ureteral ligation (UUO). Quercetin, kaempferol, luteolin, beta-sitosterol, wogonin, stigmasterol, isorhamnetin, baicalein, and dihydrotanshinlactone progesterone were identified as the main active components of YSHXD in the treatment of unilateral ureteral ligation-induced RF, with IL-6, IL1β, TNF, AR, and PTGS2 as core target proteins. Molecular docking and molecular dynamics simulations further confirmed the relationship between compounds and target proteins. The potential molecular mechanism of YSHXD predicted by network pharmacology analysis was confirmed in HK-2 cells and UUO rats. YSHXD downregulated NLRP3, ASC, NF-κBp65, Caspase-1, GSDMD, PTGS2, IL-1β, IL-6, IL-18, TNF-α, α-SMA and upregulated HGF, effectively alleviating the RF process. YSHXD exerts important anti-inflammatory and anti-cellular inflammatory necrosis effects by inhibiting the NLRP3/caspase-1/GSDMD-mediated pyroptosis pathway, indicating that YSHXD represents a new strategy and complementary approach to RF therapy.

Tongluo Yishen Decoction Ameliorates Renal Fibrosis via NLRP3-Mediated Pyroptosis In Vivo and In Vitro.

Purpose: In this study, we investigated the mechanism of Tongluo Yishen (TLYS) decoction in more detail, from the perspective of pyroptosis in the unilateral ureteral ligation (UUO) model and the hypoxia-induced renal tubular epithelial (NRK-52E) cell. Method: The UUO model was used, and after 14 days of TLYS intervention, rats were tested for blood creatinine and urea nitrogen, HE staining was used to observe the pathological changes in the kidney, Masson staining was used to assess the degree of interstitial fibrosis, western blot was used to detect the changes of α-smooth muscle actin (α-SMA) protein expression level, immunohistochemistry and western blot detected the changes in protein expression levels of NOD-like receptor protein 3 inflammasome (NLRP3), gasdermin D (GSDMD), cysteinyl aspartate specific proteinase (caspase-1), interleukin 18 (IL-18) and interleukin 1β (I L-1β). A hypoxia model was created using NRK-52E cell, and after different concentrations of TLYS decoction intervention, the changes in the expression levels of pyroptosis were used with immunofluorescence and western blot methods. Results: TLYS decoction improved renal function, delayed the advancement of renal interstitial fibrosis, and inhibited pyroptosis in UUO rats. Furthermore, we observed that TLYS can mitigate hypoxia-induced NRK-52E cell damage via the suppression of the NLRP3-mediated pyroptosis. Conclusion: TLYS decoction exert renoprotective effects by inhibiting NLRP3-mediated pyroptosis.

MO453: Post-Translational Guanidinylation of Apolipoprotein C3 (APOC3) is Associated With Kidney and Vascular Injury

Abstract BACKGROUND AND AIMS Cardiovascular diseases (CVD) and chronic kidney diseases (CKD) are highly prevalent in Western populations and account for a substantial proportion of mortality. We recently found that apolipoprotein C-3 (ApoC3), a constituent of triglyceride-rich lipoproteins, induces alternative NLRP3 inflammasome activation leading to sterile inflammation. In the present study, we aimed to assess post-translational modifications (PTMs) of ApoC3 in patients with CKD, to determine the effects of post-translationally modified ApoC3 in vitro and in vivo, and to test the relevance in a prospective clinical trial. METHOD Using mass-spectrometry, we screened ApoC3 for PTMs We determined the effects of modified ApoC3 on monocyte inflammatory response in vitro and assessed its effects in humanized mice subjected to a vascular injury model and unilateral ureter ligation. Finally, we assessed the association of post-translationally modified ApoC3 and cardiovascular and renal events in a prospective clinical trial of 543 CKD patients. RESULTS We identified post-translational guanidinylation of ApoC3 (gApoC3) in patients with CKD, which augments the proinflammatory effects of ApoC3. Mechanistically, guanidine and urea induced guanidinylation of ApoC3. gApoC3 accumulates in kidneys and plasma of mice subjected to a CKD model as determined by 2D-proteomic analyses. In humanized mice, gApoC3 promotes kidney fibrosis and impedes vascular regeneration. In the clinical trial, higher gApoC3 blood levels as determined by mass spectrometry were associated with increased mortality as well as cardiovascular and renal events. CONCLUSION Guanidinylation of ApoC3 represents a novel pathogenic mechanism in CKD and CKD-associated vascular injury, rendering gApoC3 a potential therapeutic target.

Exploring the Mechanism of Astragalus propinquus Schischkin and Panax Notoginseng (A&P) Compounds in the Treatment of Renal Fibrosis and Chronic Kidney Disease Based on Integrated Network Analysis.

Astragalus propinquus Schischkin and Panax notoginseng (A&P) has been widely used in clinical practice to treat chronic kidney disease (CKD) for many years and achieved a remarkable improvement of these outcomes. However, its mechanisms for ameliorating CKD are still poorly obscure. In the current study, integrated network analysis was carried out to analyze the potential active ingredients and molecular mechanism of A&P on CKD, and 39 active ingredients and a total of 570 targets were obtained. Furthermore, the potential disease-related genes were obtained from the NCBI GEO database by integrating 2 microarray datasets, and 24 significant genes were utilized for subsequent analysis. Gene Ontology (GO) and Kyoto Encyclopedia of Genes and Genomes (KEGG) enrichment analysis displayed that pathways including cell oxidative stress and Akt signaling pathway are medicated by A&P. Of note, Heat Shock Transcription Factor 1 (HSF1) and RELA Proto-Oncogene (RELA) were regarded as hub genes considering their central roles in the gene regulatory network. What's more, the effect of A&P and potential genes was furthermore verified by using unilateral ureteral ligation (UUO) in rodent model. The results showed that the expression of HSF1 and RELA both at transcript and protein level was significantly upregulated in UUO model, but the expression was markedly reversed after A&P intervention. To further guide the interpretation of active ingredients from A&P on the effect of HSF1 and RELA, we performed a molecular docking assay and the results showed that active ingredients such as coptisine docked well into HSF1 and RELA. In total, these results suggest that A&P may improve RF in CKD by regulating HSF1 and RELA, which provides a basis for further understanding the mechanism of A&P in the treatment of RF and CKD.

Modulation effects of Etlingera elatior ethanol extract as anti-inflammatory on chronic kidney disease in mice with hypertension and diabetes.

The incidence of diabetes increased significantly around the world in accordance with lifestyle and change in eating behaviour. Streptozotocin-Nicotinamide (STZ-NA) is capable of inducing Diabetes Mellitus type 2 in experimental animals for insulin resistance. In this research, we inspect the therapeutic potential of Etlingera elatior ethanol extract (EEEE) on diabetes associated with diabetic nephropathy and hypertension complications in mice models. Diabetes and hypertension are induced in mice using STZ 45 mg/kgBB and NA 110 mg/kgBB, followed by unilateral ureter ligation (UUO) for 4 weeks after a week of STZ-NA induction. The EEEE solution was given in the last 4 weeks with doses of 200, 400, 600, and 800 mg/kgBB. The results of this study prove the effect of vanillic acid on improving systolic blood pressure, plasma creatinine, plasma glucose, albuminuria and reducing the inflammatory marker high sensitivity C-reactive protein (hs-CRP). Histopathology of kidney is under investigation for being part of diabetes hypertension pathology. Treatment using EEEE 600 and 800 mg/kgBB for 4 weeks in experimental mice results in the decrease of plasma glucose, systolic blood pressure, plasma creatinine, albuminuria, and hs-CRP, including the restoration of kidney histology significantly compared to 200 and 400 mg/kgBB doses. This result concludes that EEEE offers modulation effects on diabetes hypertension control by reducing blood glucose rate, blood pressure rate, kidney defect, and inflammation markers.

Hirudin, a thrombin inhibitor, attenuates TGF-β-induced fibrosis in renal proximal tubular epithelial cells by inhibition of protease-activated receptor 1 expression via S1P/S1PR2/S1PR3 signaling.

Renal interstitial fibrosis (RIF) is the final common outcome of numerous chronic kidney diseases, contributing to end-stage renal disease. Hirudin, a thrombin inhibitor, has attracted increased attention as a potential treatment approach for renal fibrosis. The present study aimed to investigate the molecular mechanism underlying the effect of hirudin on fibrosis in renal proximal tubular epithelial cells. An in vivo mouse RIF model established using unilateral ureteral obstruction (UUO) and an in vitro of RIF using the renal tubular epithelial cell line HK-2 treated with TGF-β were used. Expressions of sphingosine-1-phosphate (S1P) receptors (S1PR)1-4 and protease-activated receptor 1 (PAR1) were measured by reverse transcription-quantitative PCR and western blotting in mice with UUO and TGF-β induced HK-2 cells. Western blotting was used to detect the expression of N-cadherin, Slug, E-cadherin, Collagen IV, fibronectin, MMP9 and monocyte chemoattractant protein-1. Immunofluorescence staining was conducted to measure α-SMA level expression. The results demonstrated that the expression levels of S1PR1, S1PR2, S1PR3, S1PR4 and PAR1 were upregulated in both TGF-β-induced HK-2 cells and renal tissues from mice with unilateral ureteral ligation. Notably, hirudin inhibited TGF-β-induced PAR1, S1PR2 and S1PR3 upregulation in both HK-2 cells and renal tissues. Additionally, the inhibition of S1PR2 and S1PR3 resulted in PAR1 downregulation. Furthermore, treatment with S1P and PAR1 agonists abolished the effect of hirudin on the expression of EMT, fibrosis-related proteins and monocyte chemoattractant protein 1. In conclusion, hirudin attenuated TGF-β-induced fibrosis in proximal renal tubular epithelial HK-2 cells by inhibiting PAR1 expression via the S1P/S1PR2/S1PR3 signaling pathway. Therefore, hirudin may be considered as a promising therapeutic agent for RIF.

Gasdermin E Deletion Attenuates Ureteral Obstruction- and 5/6 Nephrectomy-Induced Renal Fibrosis and Kidney Dysfunction.

Renal fibrosis contributes to kidney dysfunction in various chronic kidney diseases (CKDs). Renal fibrosis can be driven by renal tubular cell death and inflammation. Deletion of gasdermin E (GSDME), an executor of pyroptosis, has been reported to suppress renal tubular cell pyroptosis in several models of kidney injury. However, additional evidence confirming the role of GSDME in regulating renal fibrosis and kidney function in different CKDs is required. In our study, N-GSDME expression was significantly elevated in CKD models in vivo and in vitro. GSDME deletion alleviated renal fibrosis and inflammation in both unilateral ureteral ligation (UUO) and 5/6 nephrectomy (5/6Nx) models along with the attenuation of renal dysfunction. N-GSDME overexpression had a detrimental effect on fibrotic responses in UUO kidneys and TGF-β1-treated renal tubular epithelial cells. In addition, administration of caspase-3 inhibitor Z-DEVD-FMK, which inhibits caspase-3-mediated GSDME cleavage, protected against renal fibrosis both in vivo and in vitro. Collectively, these results provide evidence that the activation of GSDME is critical in regulating both renal fibrosis and kidney dysfunction possibly via promoting inflammatory responses in CKD. These findings may offer new insights into the identification of new therapeutic targets for protecting against CKDs.

Periodontitis aggravates renal inflammatory response in a mouse model of renal fibrosis.

To assess the effects of periodontitis on renal interstitial fibrosis in a mouse model. Thirty C57BL/6 male mice were divided into control, periodontitis (PD), unilateral ureteral ligation (UUO) and PD+UUO groups. Unilateral ureteral ligation was performed 6days after periodontitis. After 2weeks, all mice were sacrificed, and samples were collected for the assessment of gene expression, immune cells, biochemical indicators and renal pathology. Expression of tumour necrosis factor-α, interleukin-1β, and Ly6G in the kidneys in the PD+UUO group was significantly greater than in the UUO group. The percentage of CD11b+ Ly6G+ cells was significantly higher in the PD+UUO than in the UUO group. Fibrotic areas in the kidneys in the PD+UUO group were slightly, but not significantly, greater than those in the UUO group. Kidneys from the PD+UUO group showed markedly higher gene expression of matrix metalloproteinase-9, but not α-smooth muscle actin or collagen I, than those in the UUO group. There were no significant differences in blood urea nitrogen, serum creatinine and uric acid between the PD+UUO and UUO groups. Periodontitis increases the renal inflammatory response without showing a significant influence on renal interstitial fibrosis or renal function in the UUO mouse model.

Retracted] Artificial Intelligence Imaging to Observe the Protective Effect of Hydrogen Sulfide on Acute Kidney Injury Caused by Urinary Sepsis

With the development of medical technology products and the rapid development of computer technology, medical AI has become a hotbed in scientific research and clinical practice. Some medical AI‐assisted diagnosis has been applied to the clinic to assist doctors in formulating treatment plans. The traditional method of clinical diagnosis and treatment is that the physician makes an intentional diagnosis and then performs ancillary tests. The clinician performs diagnosis and treatment by identifying clinical symptoms and analyzing auxiliary examination results. Modern medical AI is based on big data collection and analyzes the test results through artificial intelligence and computer algorithms. It can output diagnostic results with high sensitivity and specificity for clinical tests. Acute kidney injury (AKI) is a common clinical emergency. The main clinical features are elevated blood creatinine, decreased urine output, and sharp decline in renal function within a short period of time, and it is a hot spot worldwide. In this experiment, a rabbit sepsis model was replicated by inoculating E. coli bacteria into the rabbit’s unilateral ureteral lumen and ligation. NaHS was used as an exogenous hydrogen sulfide donor to observe the effects of hydrogen sulfide on UTIs. The protective effect of oxidative stress and inflammatory response in acute kidney injury with hyperemia. In the experiment, the production of endogenous hydrogen sulfide was decreased in the Sepsis group, and the renal CSE activity was decreased, while the content of endogenous hydrogen sulfide in the NaHS group was higher than that of the Sepsis group, and the CSE activity of renal tissue was increased. It can be seen that the plasma hydrogen sulfide and renal tissue SCE levels in septic acute kidney injury increased after NaHS intervention, and the renal tissue damage was reduced, suggesting that hydrogen sulfide is mainly generated endogenously through the action of CSE, which causes damage to the kidneys. The expressions of iNOS and HO‐1 in renal tissues of urinary sepsis are increased. H2S can play a certain protective effect on acute kidney injury in urinary sepsis by down‐regulating iNOS and up‐regulating the expression of HO‐1.

SO082LATENT TRANSFORMING GROWTH FACTOR BETA BINDING PROTEIN (LTBP4) CAN REGULATE RENAL FIBROSIS AND ALTER INFLAMMATION AND MITOCHONDRIAL DYSFUNCTION IN CHRONIC KIDNEY DISEASE (CKD)

Abstract Background and Aims: Transforming growth factor beta (TGF-beta) has been well known as a key factor for fibrosis and inflammation. LTBPs regulate TGF-beta signalling in complicated ways. Disruption and loss of LTBP4 expression is associated with abnormal accumulation of extracellular matrix (ECM) and altered TGF-beta activation. However, the role of LTBP4 in chronic kidney disease remains largely unknown. We aim to explore the mechanisms of LTBP4-related regulation in kidney disease. Method: To investigate the impact of LTBP4 on tubulointeresitial fibrosis (TIF), we generated LTBP4-overexpression human renal proximal tubule cells (HK-2), treated with exogenous TGF-beta and established a fibroblasts-HK-2 co-culture system using rat fibroblasts (NRK-49F) and HK-2 cells. Moreover, to create TIF model, we performed unilateral ureteral ligation (UUO) in Ltbp4S-/- mice and wild-type (WT) mice to check ECM deposition and phenotypic alterations. In addition, we performed RNA-Sequencing analysis to understand transcriptomic changes associate with LTBP4 overexpression. Results: Up-regulation of Ltbp4 in fibrotic kidney was noted in TIF model with UUO and in renal tissue with diabetic nephropathy. LTBP4-overexpression reduced epithelial-mesenchymal transition (EMT) with showing increased epithelial-cadherin, reduced vimentin and collagen I in the co-culture system. Moreover, higher expression of fibronectin, collagen I and alpha-smooth muscle actin (alpha-SMA) were noted in fibrotic kidneys in Ltbp4S-/- mice compared with changes in WT mice, suggesting inflammation condition could be altered by the absence of Ltbp4S. The inflammatory change in renal tissue in UUO model was studied with F4/80 stain. Increased macrophage infiltration and increased monocyte chemoattractant protein-1 (MCP-1) expression were detected in Ltbp4S-/- mice compared with that in WT mice. In addition, LTBP4-overexpression reduced mitochondrial biogenesis. Conclusion: Ltbp4 acted as a regulator of fibrosis and inflammation in fibrotic kidneys. TGF-beta- induced EMT were clearly enhanced in ltbp4 deficient environments, accompanied with reduced macrophage infiltration, which could be the major mechanism related to LTBP4/TGF-beta pathways. Furthermore, altered ATP production and usage as well as mitochondria respiration could be regulated by LTBP4 in renal failure.

Expression of EphrinA1, vascular endothelial growth factor and microRNA-210 after hydronephrosis

Objective To investigate the difference and correlations of the EphrinA1, vascular endothelial growth factor (VEGF) expression and microRNA (miRNA)-210 in the kidney tissue of rats in the unilateral ureteral obstruction (UUO) model. And to understand the regulation mechanism of the three factors in the occurrence of renal tissue injury in rats. Methods Using unilateral ureteral ligation to establish a model of hydronephrosis in mice (except for the NC group), and they wrere randomly divided into an acute hydronephrosis group (UUO group) and a false surgical control group (NC group). The UUO group was divided into four groups (UUO 2 d group, UUO 5 d group, UUO 9 d group, and UUO 14 d group), and eight mice in each group. The pathological changes of renal tissue were observed by hematoxylin-eosin (HE) staining. Quantitative real-time polymerase chain reaction (qRT-PCR) was used to detect the mRNA expression of EphrinA1, VEGF and miRNA-210; Western blot was used to detect the protein expression of EphrinA1 and VEGF. Resulsts Hydronephrosis was not shown in the NC group, and hydronephrosis and inflammatory cell infiltration were observed in the UUO group. Compared with NC group, the mRNA expression of EphrinA1 , VEGF and miRNA-210 were up-regulated in UUO 2 d group (P<0.05). With the extension of the time of hydronephrosis, the expressions of all three factors were down-regulated in 9 d and 14 d groups compared with 2 d and 5 d groups, and reached the lowest point at 14 d (P<0.05); Western blot result indicated that the expression of EphrinA1 and VEGF in renal tissue of UUO 2 d and 5 d group was increased compared with NC group (P<0.05). Conclusions The UUO mouse model verified that miRNR-210 participated in hydronephrosis. The consistency of EphrinA1, VEGF, and miRNA-210 indicated that the three factors played an important role in the occurrence and development of UUO. Key words: Hydronephrosis; Ephrin-A1; Vascular endothelial growth factor; MicroRNAs; Mice

Effect of erythropoietin on the expression of aquaporin 2-3 after the release of unilateral ureter obstruction in young rats

Objective To investigate the effect of erythropoietin (EPO) on the expression of aquaporin 2-3 after the release of unilateral ureter obstruction in young rats. Methods Twenty-four SD rats were randomly divided into 3 groups(CUUO-R group, CUUO-R+ EPO group and sham group, with 8 rats in each group). The CUUO-R model was built through unilateral ureteral ligation, after 48 h the obstruction was released.EPO was given to the CUUO-R+ EPO group at the time point of removing obstruction, and then repeated every other day for 1 week, and the same volume of saline was simultaneously given to the CUUO-R rats.The rats in sham group experienced the laparotomy and free dissection of left ureter but not ligation.The kidneys were harvested 7 d after the release of CUUO.The methods of Western blot and immunohistochemistry were used to examine the effects of erythropoietin on the expression of AQP2 and AQP3. Results The osmotic pressure of CUUO-R+ EPO group was higher than those of CUUO-R group, but lower than that of sham group(P=0.007). The concentration of creatinine and urea in the CUUO-R group[(58.001±2.416) μmol/L and (9.025±1.158) mmol/L]were higher than those of CUUO-R+ EPO group [(57.072±2.286) μmol/L and (1.479±0.043) mmol/L] and sham group [(54.820±1.536) μmol/L and (6.929±0.604) mmol/L]. The differences of the concentration of creatinine and urea between CUUO-R group and sham group were statistically significant(P 0.05). The immunohistochemistry showed that the expressions of AQP2 and AQP3 in co-llecting duct in CUUO-R group were significantly weaker than those of in sham group, and the expression of those in CUUO-R+ EPO group were slightly weaker than sham group.These results were further confirmed by Western blot, as the relative quantity of AQP2 and AQP3 were also the lowest in CUUO-R group(AQP2 in 3 groups were 0.974±0.109, 1.923±0.097 and 2.002±0.044, F=392.4, P=0.000; AQP3 in 3 groups were 0.941±0.048, 1.497±0.043 and 1.863±0.043, F=735.8, P=0.000). Conclusions EPO treatment is beneficial for the recovery expre-ssion of AQP2 and AQP3 as well as renal function at the early period after the release of ureteral obstruction in young rats. Key words: Erythropoietin; Ureter obstruction; Aquaporin 2-3; Rats

SAT-192 LOSS OF MACROPHAGE-SPECIFIC TLR4 INHIBITS OBSTRUCTIVE RENAL FIBROSIS BY BLOCKING MACROPHAGE-TO-MYOFIBROBLAST TRANSITION VIA A BAMBI-DEPENDENT MECHANISM

Macrophages are a key inflammatory cell that plays a critical role in acute and chronic kidney diseases. Toll-like receptor (TLR) 4 is highly expressed on inflammatory macrophages and has been shown to trigger acute renal inflammation. However, the role of macrophage-specific TLR4 in progression of chronic kidney disease remains unclear, which was investigated in the present study in a mouse model of unilateral ureter ligation (UUO). A mouse model of UUO was induced in Tlr4flox/floxand lysozyme Mpromoter-driven cre(LysM-cre) transgenic mice (C57BL/6). Role and mechanisms of TLR4 in macrophage-mediated renal fibrosis were studied. UUO led to remarkably F4/80+macrophage and CD3+/CD4+T cell infiltration and progressive renal fibrosis in Tlr4flox/floxmouse kidney. In contrast, deletion of macrophage-specific TLR4 blunted these inflammatory responses in LysM-cre/Tlr4flox/flox animals. Mechanistically, these inhibitory effects on renal inflammation and fibrosis in LysM-cre/Tlr4flox/floxmice were associated with the shift of macrophages from M1 (F4/80+/iNOS+) to M2 phenotype (F4/80+/CD206+). Most importantly, we also found that deletion of TLR4 from macrophage largely suppressed progressive renal fibrosis by inhibiting macrophage-to-myofibroblast transition (MMT) as identified by F4/80+αSMA+cells. This novel observation suggests that macrophage-TLR4 may trigger inflammatory M1 macrophage activation and subsequent transition to the fibrogenic phenotype via the MMT process. Further studies revealed that BMP and activin membrane-bound inhibitor (Bambi), a TGF-β1 pseudoreceptor that competitively inhibits the binding of active TGF-β1 to receptor, was also highly upregulated in LysM-cre/Tlr4flox/floxmouse kidney after UUO. Thus, macrophages lacking TLR4 showed an anti-inflammatory and anti-fibrotic phenotype as demonstrated by high levels of Bambi but low levels of TGF-b/Smad3 signaling, MMT, and renal fibrosis in vivoand in vitro. Deletion of macrophage-specific TLR4 ameliorates obstructive renal injury by promoting anti-inflammatory macrophage polarization and inhibiting MMT-mediated renal fibrosis via a Bambi-dependent mechanism. Results from this study suggest that targeting the macrophage-specific TLR4 pathway may represent a novel therapeutic intervention for renal inflammation and fibrosis.

Reduced asymmetric dimethylarginine accumulation through inhibition of the type I protein arginine methyltransferases promotes renal fibrosis in obstructed kidneys.

The role of asymmetric dimethylarginine (ADMA) in chronic kidney disease (CKD) is unclear. Through inhibition of type I protein arginine methyltransferases (PRMTs), a novel strategy, we aimed to determine the effect of ADMA on renal fibrosis and explore its underlying working mechanisms. After sham or unilateral ureter ligation (UUO) operation, 20-25 g male c57 mice were treated with vehicle or PT1001B, an inhibitor of type I PRMTs, for 13 d. Moreover, human kidney 2 (HK2) and normal rat kidney 49F (NRK-49F) cells were treated with various concentrations of PT1001B or ADMA in the presence of 2.5 ng/ml TGF-β. We found that treatment with PT1001B increased the deposition of extracellular matrix proteins, the expression of α smooth muscle actin, and connective tissue growth factor in UUO-induced fibrotic kidneys, which is correlated with reduced expression of PRMT1, reduced the production of ADMA, and increased expression of uromodulin. In TGF-β-stimulated HK2 and NRK-49F cells, PT1001B dose-dependently inhibited ADMA production, increased NO concentrations, and enhanced the expression of profibrotic proteins. Exogenous addition of ADMA inhibited the expression of profibrotic proteins dose-dependently and attenuated the profibrotic effect of PT1001B. Moreover, ADMA reduced the NO concentration in PT1001B-treated HK2 cells. Finally, we conclude that ADMA has an antifibrotic effect in obstructed kidneys, and future application of type I PRMT inhibitor should be done cautiously for patients with CKD.-Wu, M., Lin, P., Li, L., Chen, D., Yang, X., Xu, L., Zhou, B., Wang, C., Zhang, Y., Luo, C., Ye, C. Reduced asymmetric dimethylarginine accumulation through inhibition of the type I protein arginine methyltransferases promotes renal fibrosis in obstructed kidneys.

Microvesicles containing miR-34a induce apoptosis of proximal tubular epithelial cells and participate in renal interstitial fibrosis.

Function and potential mechanism of microvesicles (MVs) containing microRNA34a in renal interstitial fibrosis were investigated. A rat model of renal interstitial fibrosis was established by unilateral ureteral ligation (UUO). Rat proximal tubular epithelial cell line (NRK-52E) was used to explore the effect of MVs containing microRNA-34a on tubular epithelial cells during fibrosis, which were secreted by tubulointerstitial fibroblasts. Regardless of the UUO renal interstitial fibrosis model, or the TGF-β1-treated renal tubular epithelial cells, microRNA-34a was increased in the MVs secreted by tubulointerstitial fibroblasts. miR-34a could be transmitted through the damaged tubule basement membrane to proximal tubular epithelial cells, where it induced apoptosis of renal tubular epithelial cells by inhibiting the expression of Bcl-2, further aggravating renal interstitial fibrosis. MicroRNA-34a secreted by damaged renal interstitial fibroblasts can promote renal tubular epithelial cell apoptosis and participate in renal interstitial fibrosis by inhibiting Bcl-2.

The uroplakin plaque promotes renal structural integrity during congenital and acquired urinary tract obstruction.

Urinary tract obstruction represents a common cause of kidney injury across the human life span, resulting in chronic kidney disease and end-stage renal disease. Yet, the extent of obstructive renal damage can be heterogeneous between individuals, implying the existence of unknown mechanisms that protect against or accelerate kidney injury. In this study, we investigated the role of urothelial remodeling in renal adaptation during congenital and acquired obstruction. In the Megabladder ( Mgb-/-) model of congenital obstruction and unilateral ureteral ligation model of acute obstruction, progressive hydronephrosis is strongly associated with dynamic reorganization of the renal urothelium, which elaborates a continuous uroplakin (Upk) plaque. This led us to postulate that the Upk plaque prevents parenchymal injury during urinary tract obstruction. To test this hypothesis, we interbred Mgb-/- and Upk1b-/- mice, which lack the critical Upk1b subunit for Upk plaque formation. Upk1b-/-; Mgb-/- mice experienced an accelerated onset of bilateral hydronephrosis with severe (>67%) parenchymal loss, leading to renal failure and mortality in adolescence. To investigate the function of the renal Upk plaque during acute obstruction, we destabilized the Upk plaque by Upk1b deletion or genetically depleted Upk+ cells following unilateral ureteral obstruction. Both of these strategies accelerated renal parenchymal loss following ureteral ligation, attesting to a conserved, stabilizing role for Upk plaque deposition in the acutely obstructed kidney. In aggregate, these complementary experiments provide the first evidence that the Upk plaque confers an essential, protective adaptation to preserve renal parenchymal integrity during congenital and acquired urinary tract obstruction.

Beneficial effects of Oltipraz, nuclear factor - erythroid – 2 - related factor 2 (Nrf2), on renal damage in unilateral ureteral obstruction rat model

ABSTRACTIntroduction:We investigated whether Oltipraz (OPZ) attenuated renal fibrosis in a unilateral ureteral obstruction (UUO) rat model.Materials and Methods:We randomly divided 32 rats into four groups, each consisting of eight animals as follows: Rats in group 1 underwent a sham operation and received no treatment. Rats in group 2 underwent a sham operation and received OPZ. Rats in group 3 underwent unilateral ureteral ligation and received no treatment. Group 4 rats were subjected to unilateral ureteral ligation plus OPZ administration. Transforming growth factor beta-1 (TGF-β1), E-cadherin, nitric oxide (NO) and hydroxyproline levels were measured. Histopathological and immunohistochemical examinations were carried out.Results:TGF-β1, NO and E-cadherin levels in the UUO group were significantly higher than the sham group and these values were significantly different in treated groups compared to the UUO group. In rats treated with UUO + OPZ, despite the presence of mild tubular degeneration and less severe tubular necrosis, glomeruli maintained a better morphology when compared to the UUO group. Expressions of α-SMA in immunohistochemistry showed that the staining positivity decreased in the tubules of the OPZ-treated group.Conclusions:While the precise mechanism of action remains unknown, our results demonstrated that OPZ exerted a protective role in the UUO-mediated renal fibrosis rat model highlighting a promising therapeutic potency of Nrf2-activators for alleviating the detrimental effects of unilateral obstruction in kidneys.