Unilateral Ureteral Obstruction Operation Research Articles

Spatiotemporal delivery of multiple components of rhubarb-astragalus formula for the sysnergistic treatment of renal fibrosis.

Rhubarb (Rheum palmatum L.) and astragalus (Radix astragali) find widespread used in clinical formulations for treating chronic kidney disease (CKD). Notably, the key active components, total rhubarb anthraquinone (TRA) and total astragalus saponin (TAS), exhibit superiority over rhubarb and astragalus in terms of their clear composition, stability, quality control, small dosage, and efficacy for disease treatment. Additionally, astragalus polysaccharides (APS) significantly contribute to the treatment of renal fibrosis by modulating the gut microbiota. However, due to differences in the biopharmaceutical properties of these components, achieving synergistic effects remains challenging. This study aims to develop combined pellets (CPs) and evaluate the potential effect on unilateral ureteral obstruction (UUO)-induced renal fibrosis. The CPs pellets were obtained by combining TRA/TAS-loaded SNEDDS pellets and APS-loaded pellets, prepared using the fluidized bed coating process. The prepared pellets underwent evaluation for morphology, bulk density, hardness, and flowing property. Moreover, the in vitro release of the payloads was evaluated with the CHP Type I method. Furthermore, the unilateral ureteral obstruction (UUO) model was utilized to investigate the potential effects of CPs pellets on renal fibrosis and their contribution to gut microbiota modulation. The ex-vivo study demonstrated that the developed CPs pellets not only improved the dissolution of TRA and TAS but also delivered TRA/TAS and APS spatiotemporally to the appropriate site along the gastrointestinal tract. In an animal model of renal fibrosis (UUO rats), oral administration of the CPs ameliorated kidney histological pathology, reduced collagen deposition, and decreased the levels of inflammatory cytokines. The CPs also restored the disturbed gut microbiota induced by UUO surgery and protected the intestinal barrier. The developed CPs pellets represent a promising strategy for efficiently delivering active components in traditional Chinese medicine formulas, offering an effective approach for treating CKD.

Attenuation of renal fibrosis in mice due to lack of bombesin receptor-activated protein homologue.

Bombesin receptor-activated protein (BRAP), encoded by the C6orf89 gene in humans, is expressed in various cells with undefined functions. BC004004, the mouse homologue of C6orf89, has been shown to play a role in bleomycin-induced pulmonary fibrosis through the use of a BC004004 gene knockout mouse (BC004004-/-). In this study, we investigated the potential involvement of BRAP in renal fibrosis using two mouse models: unilateral ureteral obstruction (UUO) and type 2 diabetes mellitus induced by combination of a high-fat diet (HFD) and streptozocin (STZ). BRAP or its homologue was expressed in tubular epithelial cells (TECs) in the kidneys of patients with chronic kidney disease (CKD) and in BC004004+/+ mice. Compared to control mice, BC004004-/- mice exhibited attenuated renal injury and renal fibrosis after UUO or after HFD/STZ treatment. Immunohistochemistry and immunoblot analyses of the kidneys of BC004004+/+ mice after UUO surgery showed a more significant decrease in E-cadherin expression and a more significant increase in both α smooth muscle actin (α-SMA) and vimentin expression compared to BC004004-/- mice. Additionally, stimulation with transforming growth factor-β1 (TGF-β1) led to a more significant decrease in E-cadherin expression and a more significant increase in α-SMA and vimentin expression in isolated TECs from BC004004+/+ than in those from BC004004-/- mice. These results suggest that an enhanced epithelial-mesenchymal transition (EMT) process occurred in TECs in BC004004+/+ mice during renal injury, which might contribute to renal fibrosis. The loss of the BRAP homologue in BC004004-/- mice suppressed EMT activation in kidneys and contributed to the suppression of fibrosis during renal injury.

USP11 promotes renal tubular cell pyroptosis and fibrosis in UUO mice via inhibiting KLF4 ubiquitin degradation.

The pyroptosis of renal tubular epithelial cells leads to tubular loss and inflammation and then promotes renal fibrosis. The transcription factor Krüppel-like factor 4 (KLF4) can bidirectionally regulate the transcription of target genes. Our previous study revealed that sustained elevation of KLF4 is responsible for the transition of acute kidney injury (AKI) into chronic kidney disease (CKD) and renal fibrosis. In this study, we explored the upstream mechanisms of renal tubular epithelial cell pyroptosis from the perspective of posttranslational regulation and focused on the transcription factor KLF4. Mice were subjected to unilateral ureteral obstruction (UUO) surgery and euthanized on D7 or D14 for renal tissue harvesting. We showed that the pyroptosis of renal tubular epithelial cells mediated by both the Caspase-1/GSDMD and Caspase-3/GSDME pathways was time-dependently increased in UUO mouse kidneys. Furthermore, we found that the expression of the transcription factor KLF4 was also upregulated in a time-dependent manner in UUO mouse kidneys. Tubular epithelial cell-specific Klf4 knockout alleviated UUO-induced pyroptosis and renal fibrosis. In Ang II-treated mouse renal proximal tubular epithelial cells (MTECs), we demonstrated that KLF4 bound to the promoter regions of Caspase-3 and Caspase-1 and directly increased their transcription. In addition, we found that ubiquitin-specific protease 11 (USP11) was increased in UUO mouse kidneys. USP11 deubiquitinated KLF4. Knockout of Usp11 or pretreatment with the USP11 inhibitor mitoxantrone (3 mg/kg, i.p., twice a week for two weeks before UUO surgery) significantly alleviated the increases in KLF4 expression, pyroptosis and renal fibrosis. These results demonstrated that the increased expression of USP11 in renal tubular cells prevents the ubiquitin degradation of KLF4 and that elevated KLF4 promotes inflammation and renal fibrosis by initiating tubular cell pyroptosis.

Novel glucomannan-like polysaccharide from Lycium barbarum L. ameliorates renal fibrosis via blocking macrophage-to-myofibroblasts transition

The macrophage to myofibroblasts transition (MMT) has been reported as a newly key target in renal fibrosis. Lycium barbarum L. is a traditional Chinese medicine for improving renal function, in which its polysaccharides (LBPs) are the mainly active components. However, whether the role of LBPs in treating renal fibrosis is related to MMT process remain unclear. The purpose of this study was to explore the relationship between the regulating effect on MMT process and the anti-fibrotic effect of LBPs. Initially, small molecular weight LBPs fractions (LBP-S) were firstly isolated via Sephadex G-100 column. Then, the potent inhibitory effect of LBP-S on MMT process was revealed on bone marrow-derived macrophages (BMDM) model induced by TGF-β. Subsequently, the chemical structure of LBP-S was elucidated through monosaccharide, methylation and NMR spectrum analysis. In vivo biodistribution characteristics studies demonstrated that LBP-S exhibited effectively accumulation in kidney via intraperitoneal administration. Finally, LBP-S showed a satisfactory anti-renal fibrotic effect on unilateral ureteral obstruction operation (UUO) mice, which was significantly reduced following macrophage depletion. Overall, our findings indicated that LPB-S could alleviate renal fibrosis through regulating MMT process and providing new candidate agents for chronic kidney disease (CKD) related fibrosis treatment.

Wogonin ameliorates ER stress-associated inflammatory response, apoptotic death and renal fibrosis in a unilateral ureteral obstruction mouse model

Wogonin, a vital bioactive compound extracted from the medicinal plant, Scutellaria baicalensis, has been wildly used for its potential in mitigating the progression of chronic diseases. Chronic kidney disease (CKD) represents a significant global health challenge due to its high prevalence, morbidity and mortality rates, and associated complications. This study aimed to assess the potential of wogonin in attenuating renal fibrosis and to elucidate the underlying molecular mechanisms using a unilateral ureteral obstruction (UUO) mouse model as a CKD mimic. Male mice, 8 weeks old, underwent orally administrated of either 50 mg/kg/day of wogonin or positive control of 5 mg/kg/day candesartan following UUO surgery. NRK52E cells were exposed to tumor growth factors−beta (TGF−β) to evaluate the anti-fibrotic effects of wogonin. The results demonstrated that wogonin treatment effectively attenuated TGF-β-induced fibrosis markers in NRK-52E cells. Additionally, administration of wogonin significantly improved histopathological alterations and downregulated the expression of pro-fibrotic factors (Fibronectin, α-smooth muscle actin, Collagen IV, E-cadherin, and TGF-β), oxidative stress markers (Catalase, superoxide dismutase 2, NADPH oxidase 4, and thioredoxin reductase 1), inflammatory molecules (Cyclooxygenase-2 and TNF-α), and the infiltration of neutrophils and macrophages in UUO mice. Furthermore, wogonin treatment mitigated endoplasmic reticulum (ER) stress-associated molecular markers (GRP78, GRP94, ATF4, CHOP, and the caspase cascade) and suppressed apoptosis. The findings indicate that wogonin treatment ameliorates key fibrotic aspects of CKD by attenuating ER stress-related apoptosis, inflammation, and oxidative stress, suggesting its potential as a future therapeutic target.

#2069 Elucidating the function of novel Arg1+/Clec4d+ scar-associated monocyte-derived macrophage population in driving fibrosis in kidney disease models

Abstract Background and Aims Fibrosis is the final common pathway in all progressive kidney disease. Macrophages are a major myeloid cell component of the renal mononuclear phagocyte system, with roles in defence against infection, renal injury, and repair. Using single-cell RNA sequencing, we identified a novel myeloid cell subset exclusively present in acute injury of the unilateral ureteric obstruction (UUO) model of kidney fibrosis. This population transcriptomically aligns to monocytes but is enriched for both Arginase-1 (Arg1) and the C-type lectin 4d (Clec4d) and a large number of pro-inflammatory and pro-fibrotic genes. We hypothesise that this novel Arg1+/Clec4d+ population contributes to fibrosis deposition in progressive kidney disease. Methods Monocyte-macrophage populations were characterised in different pre-clinical models; UUO, unilateral ischaemic reperfusion injury (uIRI) and subtotal nephrectomy with flow cytometry. Arg1+/Clec4d+ cells were identified by RT-qPCR, flow cytometry, and immunofluorescence. The origin and consequence of Arg1 deletion in monocytes on renal fibrosis was determined by utilising Ccr2-ERT2-TdTomato and Ccr2-ERT2-TdTomato; Arg1 fl/fl mice, respectively. Results The presence of the Arg1+/Clec4d+ cells was validated in the UUO, uIRI and subtotal nephrectomy models of kidney injury. Analysis of intra-renal inflammation revealed CD45+CD11b+Arg1+ cells persisted and increased in number across 7 days. Post-injury, Arg1+ cells were confirmed to be Clec4dhi. To confirm that Arg1+/Clec4d+ cells were derived from monocytes (Ccr2+), we administered tamoxifen to Ccr2CreERT2-TdTomato mice under a single or multiple-dose regimen following UUO surgery. At day 7 post-injury, ∼50% and ∼90% of the Arg1+ cells were TdTomato+ following a single or multiple doses of tamoxifen, respectively, suggesting that these cells are primarily monocyte derived. Moreover, the Arg1+/Clec4d+ cells were found to localise to areas of scarring (Fig. 1). To investigate the therapeutic potential of targeting Clec4d+ expressed on the Arg1+/Clec4d+ macrophages, mice underwent UUO surgery and given multiple doses of a Clec4d-neutralising antibody. A decrease in Arg1 and fibrosis-related gene expression was evident by day 7 post-injury. To understand the role of increased Arg1 expression in the cells we generated Ccr2-ERT2-TdTomato; Arg1 fl/fl mice. These mice had as expected a reduced Arg1 expression in the Ccr2+ population and metabolic profiling by SCENITH of the tissue monocytes revealed that the loss of Arg1 in the cells reduced their glucose dependence. The loss of Arg1 in these cells reduced Havcr1 gene expression in the kidney. Conclusion As fibrosis is a pathological process that can affect any organ, the work included here, in addition to the proposed future studies, has the potential to develop novel therapeutics that limit fibrosis and enhance repair to halt the progression of disease in CKD.

557 Dual TGFβR1/MAP4K4 inhibitor reduces kidney injury in a mouse model of renal fibrosis.

OBJECTIVES/GOALS: Renal fibrosis is a critical pathophysiological event in chronic kidney diseases. Our goal is to determine the ability of dual-inhibitor of transforming growth factor beta receptor 1 (TGFα²R1) and mitogen-activated protein kinase kinase kinase kinase 4 (MAP4K4), TK850, on reducing kidney fibrosis. METHODS/STUDY POPULATION: To test the renal anti-fibrotic action ofdual TK850,8-10-week-old male and female C57BL/6mice with unilateral ureteral obstruction (UUO) induced kidney fibrosis were used. Mice were separated into 3 groups: group 1 contained mice that had UUO surgery (UUO control), group 2 contained mice prophylactically treated with TK850 thatstarted 7 days prior to UUO(UUO-P,20 mpk/d/ip), and group 3 contained mice interventionally treated with TK850 that started3 days after UUO(UUO-I,20 mpk/d/ip). Ten days following UUO the kidneys and blood were collected for analysis. Renal fibrosis was assessed from hydroxyproline content (measure of collagen)and histological collagen analysis using Picrosirius red stain. RESULTS/ANTICIPATED RESULTS: Renal hydroxyproline was increased equally in the UUO kidney of male (5.4 ± 0.41 µg/10mg, n=5) and female mice (5.5 ± 0.50 µg/10mg, n=5) compared to the contralateral control kidney (2.9 ± 0.14 µg/10mg, n=10). TK850 treatment in UUO-P mice (n=10, 3.4 ± 0.24 µg/10mg) and UUO-I mice (4.30 ± 0.20 µg/10mg, n=10) had significantly reduced hydroxyproline levels. Histopathological evaluation revealed that kidney injury increased collagen deposition in the UUO kidney (17.1 ± 0.43% collagen positive area, n=10) compared to the control kidney (2.0 ± 0.23%, n=10). TK850 treatment in UUO-P mice significantly attenuated collagen deposition (10.5 ± 0.38%, n=10), while UUO-I had significantly reduced collagen deposition as well (13.1 ± 0.25%, n=10). DISCUSSION/SIGNIFICANCE: Taken together, these results validate the dual TGFβR1/MAP4K4 inhibitor, TK850 as a potential therapeutic to mitigate renal fibrosis and supports the emergence of a combinational pharmacotherapeutic approach for multi-factorial kidney diseases.

Dual soluble epoxide hydrolase inhibitor - farnesoid X receptor agonist interventional treatment attenuates renal inflammation and fibrosis.

Renal fibrosis associated with inflammation is a critical pathophysiological event in chronic kidney disease (CKD). We have developed DM509 which acts concurrently as a farnesoid X receptor agonist and a soluble epoxide hydrolase inhibitor and investigated DM509 efficacy as an interventional treatment using the unilateral ureteral obstruction (UUO) mouse model. Male mice went through either UUO or sham surgery. Interventional DM509 treatment (10mg/kg/d) was started three days after UUO induction and continued for 7 days. Plasma and kidney tissue were collected at the end of the experimental protocol. UUO mice demonstrated marked renal fibrosis with higher kidney hydroxyproline content and collagen positive area. Interventional DM509 treatment reduced hydroxyproline content by 41% and collagen positive area by 65%. Renal inflammation was evident in UUO mice with elevated MCP-1, CD45-positive immune cell positive infiltration, and profibrotic inflammatory gene expression. DM509 treatment reduced renal inflammation in UUO mice. Renal fibrosis in UUO was associated with epithelial-to-mesenchymal transition (EMT) and DM509 treatment reduced EMT. UUO mice also had tubular epithelial barrier injury with increased renal KIM-1, NGAL expression. DM509 reduced tubular injury markers by 25-50% and maintained tubular epithelial integrity in UUO mice. Vascular inflammation was evident in UUO mice with 9 to 20-fold higher ICAM and VCAM gene expression which was reduced by 40-50% with DM509 treatment. Peritubular vascular density was reduced by 35% in UUO mice and DM509 prevented vascular loss. Interventional treatment with DM509 reduced renal fibrosis and inflammation in UUO mice demonstrating that DM509 is a promising drug that combats renal epithelial and vascular pathological events associated with progression of CKD.

Noscapine alleviates unilateral ureteral obstruction-induced inflammation and fibrosis by regulating the TGFβ1/Smads signaling pathways

Renal fibrosis is a common pathway leading to progressive renal function loss in various forms of chronic kidney disease. Many fibrogenic factors regulate renal fibrosis; two key players are post-injury inflammation and transforming growth factor-β1 (TGF-β1)-induced myofibroblast differentiation. Myofibroblast differentiation is tightly regulated by the microtubule polymerization. Noscapine, an antitussive plant alkaloid, is a potent microtubule-interfering agent previously identified as a potential anticancer compound. Here, we examined how noscapine affects renal fibrogenesis in an in vitro renal fibroblast model and an in vivo unilateral ureteral obstruction (UUO) model. UUO mice were intraperitoneally treated with noscapine at 1 day before UUO surgery and daily thereafter. At 7 days post-surgery, kidneys were collected for further analysis. To analyze whether noscapine inhibits downstream TGF-β1-related signaling, we pre-incubated NRK-49F fibroblasts with noscapine and then performed TGF-β1 stimulation. In UUO mice, noscapine attenuated extracellular matrix protein deposition and the expression levels of type I collagen, type IV collagen, α-smooth muscle actin, and fibronectin. In addition, noscapine decreased tubulointerstitial inflammation in UUO kidneys by reducing TLR2 expression, modulating NLRP3 inflammasome activation, reducing macrophage infiltration, and antagonizing the M2 macrophage phenotype. Furthermore, noscapine pre-incubation suppressed the TGF-β1-induced fibroblast-myofibroblast transformation by downregulating the TGF-β/Smads signaling pathways in NRK-49F cells. These results suggest that noscapine reduces tubulointerstitial inflammation and fibrosis in the kidneys of UUO mice and inhibits the fibroblast-myofibroblast transformation induced by TGF-β1. Noscapine is an over-the-counter antitussive that has been used safely for several decades. Therefore, noscapine is an attractive therapeutic agent for inhibiting renal tubulointerstitial fibrosis.

Therapeutic mechanism exploration of polysaccharides from Dendrobium officinale on unilateral ureteral obstruction operation-induced renal fibrosis based on improving oxidative stress injury mediated by AhR/NOX4 pathway

Dendrobium officinale polysaccharides (DOP) has been reported to possess remarkable effects on improving renal function, oxidative stress damage and fibrotic diseases. However, the role and mechanism of DOP in preventing and treating renal fibrosis remain unclear. The purpose of this paper was to explore the therapeutic effects and underlying mechanisms of DOP on renal fibrosis. Firstly, renal fibrosis model was induced by unilateral ureteral obstruction operation (UUO) in male BALB/c mice. Subsequently, the anti-renal fibrosis effect of DOP was evaluated. It turned out that DOP significantly attenuated UUO induced renal fibrosis. The beneficial effects of DOP on renal fibrosis were concretely manifested in the relief of clinical symptoms, improvement of renal function, reduction of extracellular matrix collagen aggregation, attenuation of structural damage and inflammation, and decrement of profibrotic factors secretion. Meanwhile, DOP could also alleviate oxidative stress injury and inhibit the AhR/NOX4 pathway proteins expression. Furthermore, multivariate statistical analysis, AhR interference and overexpression experiments showed that the effect of DOP on alleviating renal fibrosis was closely related to the improvement of oxidative stress injury mediated by the AhR/NOX4 pathway. Overall, the data in the present paper indicated that DOP could alleviate renal fibrosis through improving AhR/NOX4 mediated oxidative stress injury.

Abstract P376: Collecting Duct Renin And Its Receptor Contributes To Unilateral Ureteral Obstruction-induced Kidney Injury Via Activation Of The Intrarenal Ras

The collecting duct (CD) is well known for its role in fine-tuning urinary excretion of electrolytes and water. Emerging evidence suggests a potential role played by the CD in immunity and renal injury but the underlying mechanism largely remains elusive. Within the CD, (pro)renin receptor (PRR) via site-1 protease (S1P)-derived soluble PRR interacts with renin controls the intrarenal renin-angiotensin system (RAS) to regulate Na+ and water balance and blood pressure. The present study attempted to employ mouse models of CD-specific deletion of PRR and renin (CD PRR KO and CD renin KO, respectively) and a specific S1P inhibitor PF-429242 (PF) to explore the pathogenic role of this local system in renal injury induced by unilateral ureteral obstruction (UUO). Male 3-4-month-old CD PRR KO and CD renin KO, and their respective floxed controls were subjected to UUO surgery or sham operation for 3 days, followed by analysis of renal fibrosis, inflammation, and indices of the intrarenal RAS. Male 3-4-month-old C57BL/6 mice were subjected to the same surgical procedures and infused with vehicle or PF at 20 mg/kg/day via minipump for 3 days, followed by analysis of the same parameters. 3-day UUO in floxed mice induced renal abundance of fibronectin and α-SMA by 8.6 folds and 5.8 folds, respectively, as assessed by immunoblotting analysis. qRT-PCR detected similar magnitude of increases in mRNA expression of fibronectin, α-SMA, as well as collagen III, collagen I, and TGF-β in the obstructed kidneys. Similar results were obtained by Trichrome Masson staining. In parallel, the obstructed kidney exhibited 4-5-fold increases in renal medullary renin mRNA, renin activity, and active renin content contrasting to unaltered renin levels in the renal cortex. CD-specific deletion of PRR and renin induced comparable attenuation of various indices of renal fibrosis, inflammation, renal medullary renin levels so did PF treatment. UUO induced a 2-fold increase in plasma sPRR, which was completely blocked by PF treatment. Taken together, our results demonstrated that CD PRR/sPRR-dependent activation of renin represents a key determinant of the intrarenal RAS and thus obstruction-induced renal inflammation and fibrosis.

Nephroprotective Effects of Cardamonin on Renal Ischemia Reperfusion Injury/UUO-Induced Renal Fibrosis.

Acute kidney injury and chronic renal fibrosis are intractable pathological processes to resolve, yet limited strategies are able to effectively address them. Cardamonin (CAD) is a flavonoid with talented antioxidant, anti-inflammatory capacity, and satisfactory biosafety. In our study, animal and cellular models of renal ischemia/reperfusion (I/R) and unilateral ureteral obstruction (UUO) were successfully constructed to confirm whether CAD confers protective effects and underlying mechanisms. Animal experiments demonstrated that CAD application (100 mg/kg) distinctly ameliorated tissue damage and improved renal function. Meanwhile, the continuous oral administration of CAD after UUO surgery efficiently inhibited renal fibrosis as confirmed by hematoxylin-eosin (H&E), Sirius red, and Masson staining as well as the downregulated mRNA and protein expression of collagen I, α-smooth muscle actin (α-SMA), collagen III, and fibronectin. Interestingly, in transforming growth factor β1 (TGF-β1)-stimulated and hypoxia/reoxygenation (H/R)-exposed human kidney-2 (HK-2) cells, protective effects of CAD were again authenticated. Meanwhile, we performed bioinformatics analysis and constructed the "ingredient-target-pathway-disease" network to conclude that the potential mechanisms of CAD protection may be through the regulation of oxidative stress, inflammation, apoptosis, and mitogen-activated protein kinase (MAPK) pathway. Furthermore, experimental data validated that CAD evidently decreased the reactive oxygen species (ROS) production and malondialdehyde (MDA) content while depressing the mRNA and protein expression of inflammatory markers (tumor necrosis factor-α (TNF-α), interleukin-6 (IL-6), and Il-1β) and inhibiting apoptosis as evidenced by decreased levels of P53, BAX, cleaved caspase-3, and apoptotic rate in renal I/R and UUO models. In addition, the impact of CAD on restraining oxidative stress and inflammation was attributed to its ability to elevate antioxidant enzyme activities including catalase, superoxide dismutase 1 (SOD1), and superoxide dismutase 2 (SOD2) and to inhibit the inflammation-associated MARK/nuclear factor-κB (MAPK/NF-κB) signaling pathway. In conclusion, cardamonin restored the antioxidative capacity to block oxidative stress and suppressed the MAPK/NF-κB signaling pathway to alleviate inflammatory response, thus mitigating I/R-generated acute kidney injury/UUO-induced renal fibrosis in vivo and in vitro, which indicated the potential therapeutic advantage of cardamonin in attenuating acute and chronic kidney injuries.

#3553 TUBULE CELL-DERIVED ANGIOPOIETIN-2 EXACERBATES INFLAMMATION AND IS DETRIMENTAL TO RENAL FIBROSIS

Abstract Background and Aims Our previous studies have shown that angiogenic growth factors are dysregulated in fibrotic kidneys. In murine models of progressive renal disease, angiopoietin-2 (Angpt2) was upregulated in injured tubule epithelial cells. We hypothesize that overexpression of Angpt2 in tubule epithelial cells would exacerbate renal fibrosis and inflammation. Method The unilateral ureteral obstruction (UUO) and unilateral ischemia-reperfusion injury (UIRI) are used as the murine model of chronic kidney disease. We use the tetracycline/doxycycline-controlled Tet-on system to induce tubule cell-specific overexpression of Angpt2 before the induction of renal fibrosis. Transgenic mice carrying both Pax8-rtTA and pTetos-hAngpt2 genes (double transgenic mice) are used for Angpt2 overexpression. Littermates that inherit single or no transgene serve as experimental controls. Doxycycline is administered to adult (8 weeks) mice to overexpress Angpt2 in tubule epithelial cells. Results Doxycycline administration induce overexpression of human Anpgt2 in the tubule epithelial cells of both sham and fibrotic kidneys. Compared to littermate controls after the UUO and UIRI surgery, the expression of fibrosis-related genes, Col1a1, Col3a1, and Acta2 are higher in the kidneys of double transgenic mice. Deposition of picrosirius red-stained collagen fibrils is significantly higher in double transgenic mice. Inflammatory cell infiltration is also significantly higher in double transgenic mice. Conclusion Overall, these findings suggest that increased Angpt2 in tubule epithelial cells deteriorate renal fibrosis through detrimental inflammation. Further studies are necessary to explore the participating cellular components and pathogenic mechanisms.

Novel small-molecule compound VCP979 attenuates renal fibrosis in male rats with unilateral ureteral obstruction.

Renal fibrosis is a hallmark of chronic kidney disease, while efficient therapy against renal fibrosis is still lacking. In this study, we investigated the role of a novel small-molecule compound VCP979 on renal fibrosis and inflammation in a rat model of unilateral ureteral obstruction (UUO). One week after the UUO surgery, rats were administered VCP979 by gavage for one week, and after treatment, magnetic resonance imaging of T1rho mapping and histopathological analysis were performed to evaluate renal fibrosis in vivo and ex vivo. This study showed that treatment with VCP979 effectively reduced renal fibrosis, extracellular matrix accumulation, and alleviated epithelial-mesenchymal transition in UUO rats, as well as improved renal function. In vivo T1rho mapping displayed increased T1rho values in the UUO rats, which was decreased after VCP979 treatment, and a positive correlation was detected between the T1rho values and the percentage of fibrotic area. Moreover, the administration of VCP979 also ameliorated the inflammatory cytokines expression and the infiltration of macrophages in renal tissues. Mechanistically, VCP979 treatment inhibited the activation of p38 mitogen-activated protein kinase, nuclear factor-kappa B, and transforming growth factor-β1/Smads signaling pathways. These results indicated that VCP979 could be an effective therapeutic agent for alleviating renal fibrosis and inflammation in the rat model of UUO via its antifibrotic and anti-inflammatory effects.

LIM and Cysteine-Rich Domains 1 Promotes Transforming Growth Factor β1–Induced Epithelial–Mesenchymal Transition in Human Kidney 2 Cells

Renal fibrosis is the major pathologic manifestation of chronic kidney disease (CKD). LIM and cysteine-rich domains 1 (LMCD1) is upregulated in the kidney tissue from patients with CKD and the transforming growth factor β1 (TGF-β1)–treated human renal tubular epithelial cell line human kidney 2 (HK-2) (Gene Expression Omnibus: GSE66494 and GSE23338). Previously, we have demonstrated that the knockdown of LMCD1 ameliorated renal fibrosis in mice by blocking the activation of the extracellular signal-regulated kinase pathway. In this study, we sought to further investigate whether LMCD1 affects TGF-β1–induced epithelial–mesenchymal transition (EMT) of kidney tubular epithelial cells and its potential role in the TGF-β1/Smad signaling pathway. First, we confirmed that LMCD1 expression was increased in the fibrotic kidneys of patients with CKD compared with that in normal kidneys and that LMCD1 was predominantly localized in the renal tubules. LMCD1 and mesenchymal markers were upregulated in obstructed kidney tissues of mice at 21 days after unilateral ureteral obstruction surgery compared with the tissues in sham mice. Next, we demonstrated that TGF-β1 significantly increased LMCD1 expression through Smad-mediated transcription in HK-2 cells in vitro. In turn, LMCD1 acted as a transcriptional coactivator of E2F transcription factor 1 to promote the transcription of TGF-β1. Moreover, TGF-β1 increased the interaction between LMCD1 and Smad ubiquitination regulatory factor 2 (Smurf2) and accelerated Smurf2-mediated LMCD1 degradation via the ubiquitination system. The knockdown of LMCD1 inhibited TGF-β1–induced EMT in both HK-2 cells and unilateral ureteral obstruction mice. Our results indicate a positive feedback loop between TGF-β1 and LMCD1 for EMT induction in HK-2 cells and that Smurf2 acts as a negative regulator in this process by accelerating LMCD1 degradation.

Antioxidant, Anti-Apoptotic, and Anti-Inflammatory Effects of Farrerol in a Mouse Model of Obstructive Uropathy.

Obstructive uropathy is a clinical condition that can lead to chronic kidney disease. However, treatments that can prevent the progression of renal injury and fibrosis are limited. Farrerol (FA) is a natural flavone with potent antioxidant and anti-inflammatory properties. Here, we investigated the effect of FA on renal injury and fibrosis in a mouse model of unilateral ureteral obstruction (UUO). Mice underwent a sham or UUO operation and received intraperitoneal injections of FA (20 mg/kg) daily for 8 consecutive days. Histochemistry, immunohistochemistry and immunofluorescence staining, TdT-mediated dUTP nick end labeling assay, Western blotting, gene expression analysis, and biochemical tests were performed. FA attenuated renal dysfunction (p < 0.05) and ameliorated renal tubular injury (p < 0.01) and interstitial fibrosis (p < 0.001) in UUO mice. FA alleviated 4-hydroxynonenal expression (p < 0.001) and malondialdehyde levels (p < 0.01) by regulating pro-oxidant and antioxidant enzymes. Apoptosis in the kidneys of UUO mice was inhibited by FA (p < 0.001), and this action was accompanied by decreased expression of cleaved caspase-3 (p < 0.01). Moreover, FA alleviated pro-inflammatory cytokine production (p < 0.001) and macrophage infiltration (p < 0.01) in the kidneys of UUO mice. These results suggest that FA ameliorates renal injury and fibrosis in the UUO model by inhibiting oxidative stress, apoptosis, and inflammation.

Rheum officinale and Salvia miltiorrhiza inhibit renal fibrosis via miR-21/PTEN/Akt signaling pathway in vitro and in vivo

Ethnopharmacological relevanceAs one of the main components of many famous Chinese herbal formulas, Rheum palmatum L. and Salvia miltiorhiza Bunge (RS) are extensively used to treat chronic kidney disease (CKD). RS has been proved to improve renal function and relieve renal fibrosis (RF), but the potential mechanism remains a mystery. Aim of the studyThe purpose of this study is to determine whether microRNA-21 (miR-21) is associated with RF progression, as well as whether RS protects against RF through miR-21/PTEN/AKT signaling. Materials and methods(1) The rat model of RF was established using unilateral ureteral obstruction (UUO). After UUO surgery, miR-21 levels in plasma were detected by RT-PCR and RF scores were assessed by Masson's trichrome stain at days 3, 7, 14 and 21. The correlation analysis of the above two indexes was carried out by Spearman correlation analysis. (2) Human proximal tubular epithelial cells (HK-2) was transfected with miR-21 mimic and inhibitor, and then the levels of phosphatase and tensin homolog (PTEN) protein and mRNA were measured with Western blotting and RT-PCR, respectively. (3) TGF-β (10 ng/mL) was added into HK-2 cells to induce fibrosis, followed by the intervention of RS-containing rat serum. PTEN and protein kinase-B (Akt) phosphorylation, as well as the expression of PTEN protein in HK-2 cells, were assessed by RT-PCR, Western blotting and immunofluorescence. (4) The rat models of RF were prepared by UUO and treated with RS. Serum creatinine and urea nitrogen levels were measured. RF score was determined by Masson's trichrome stain. RT-PCR was used to determine the expression of miR-21, PTEN, and Akt mRNA. Western blotting was used to determine the expression of PTEN and Akt proteins. ResultsA positive correlation was found between plasma miR-21 levels and RF scores of rats after UUO surgery at Days 3, 7, 14 and 21. It was confirmed that miR-21 targeted PTEN. RS drug-containing serum could rise the expression of PTEN and reduce Akt phosphorylation of HK-2 cells induced by TGF-β. Moreover, RS drug-containing serum could increase PTEN expression and reduce Akt phosphorylation induced by miR-21 mimic in HK-2 cells. The rats treated with RS had significantly decreased serum creatinine and urea nitrogen levels and a lower RF score. RS also decreased miR-21 and Akt expressions, increased PTEN expression of UUO rats. ConclusionThere was a positive correlation between plasma miR-21 levels and RF scores. The inhibitory effect of RS on RF might be mediated by miR-21/PTEN/AKT signaling.

Novel targets in renal fibrosis based on bioinformatic analysis.

Background: Renal fibrosis is a widely used pathological indicator of progressive chronic kidney disease (CKD), and renal fibrosis mediates most progressive renal diseases as a final pathway. Nevertheless, the key genes related to the host response are still unclear. In this study, the potential gene network, signaling pathways, and key genes under unilateral ureteral obstruction (UUO) model in mouse kidneys were investigated by integrating two transcriptional data profiles. Methods: The mice were exposed to UUO surgery in two independent experiments. After 7days, two datasets were sequenced from mice kidney tissues, respectively, and the transcriptome data were analyzed to identify the differentially expressed genes (DEGs). Then, Gene Ontology (GO) and Kyoto Encyclopedia of Genes and Genomes (KEGG) analysis were executed. A Protein-Protein Interaction (PPI) network was constructed based on an online database STRING. Additionally, hub genes were identified and shown, and their expression levels were investigated in a public dataset and confirmed by quantitative real time-PCR (qRT-PCR) in vivo. Results: A total of 537 DEGs were shared by the two datasets. GO and the KEGG analysis showed that DEGs were typically enriched in seven pathways. Specifically, five hub genes (Bmp1, CD74, Fcer1g, Icam1, H2-Eb1) were identified by performing the 12 scoring methods in cytoHubba, and the receiver operating characteristic (ROC) curve indicated that the hub genes could be served as biomarkers. Conclusion: A gene network reflecting the transcriptome signature in CKD was established. The five hub genes identified in this study are potentially useful for the treatment and/or diagnosis CKD as biomarkers.

Protective Effects of Carnosol on Renal Interstitial Fibrosis in a Murine Model of Unilateral Ureteral Obstruction.

Renal fibrosis is a common feature of chronic kidney disease and is a promising therapeutic target. However, there is still limited treatment for renal fibrosis, so the development of new anti-fibrotic agents is urgently needed. Accumulating evidence suggest that oxidative stress and endoplasmic reticulum (ER) stress play a critical role in renal fibrosis. Carnosol (CS) is a bioactive diterpene compound present in rosemary plants and has potent antioxidant and anti-inflammatory properties. In this study, we investigated the potential effects of CS on renal injury and fibrosis in a murine model of unilateral ureteral obstruction (UUO). Male C57BL/6J mice underwent sham or UUO surgery and received intraperitoneal injections of CS (50 mg/kg) daily for 8 consecutive days. CS improved renal function and ameliorated renal tubular injury and interstitial fibrosis in UUO mice. It suppressed oxidative injury by inhibiting pro-oxidant enzymes and activating antioxidant enzymes. Activation of ER stress was also attenuated by CS. In addition, CS inhibited apoptotic and necroptotic cell death in kidneys of UUO mice. Furthermore, cytokine production and immune cell infiltration were alleviated by CS. Taken together, these findings indicate that CS can attenuate renal injury and fibrosis in the UUO model.

Chitosan oligosaccharide alleviates renal fibrosis through reducing oxidative stress damage and regulating TGF-β1/Smads pathway

Renal fibrosis (RF) is the common pathway for a variety of chronic kidney diseases that progress to end-stage renal disease. Chitosan oligosaccharide (COS) has been identified as possessing many health functions. However, it is not clear whether COS can prevent RF. The purpose of this paper was to explore the action and mechanism of COS in alleviating RF. First, an acute unilateral ureteral obstruction operation (UUO) in male BALB/c mice was performed to induce RF, and COS or fosinopril (positive control drug) were administered for 7 consecutive days. Data from our experiments indicated that COS treatment can significantly alleviate kidney injury and decrease the levels of blood urea nitrogen (BUN) and serum creatinine (SCr) in the UUO mouse model. More importantly, our results show that COS can reduce collagen deposition and decrease the expression of fibrosis proteins, such as collagen IV, fibronectin, collagen I, α-smooth muscle actin (α-SMA) and E-cadherin, ameliorating experimental renal fibrosis in vivo. In addition, we also found that COS suppressed oxidative stress and inflammation in RF model mice. Further studies indicated that the mechanism by which COS alleviates renal fibrosis is closely related to the regulation of the TGF-β1/Smad pathway. COS has a therapeutic effect on ameliorating renal fibrosis similar to that of the positive control drug fosinopril. Taken together, COS can alleviate renal fibrosis induced by UUO by reducing oxidative stress damage and regulating the TGF-β1/Smad pathway.