Search Results (98)

Background: The kidney is an organ rich in peroxisomes, which play a pivotal role in fatty acid oxidation and ROS decomposition. Importantly, peroxisomal dysfunction contributes to the development and progression of various renal diseases. Therefore, we aimed to elucidate whether peroxisomes affect renal damage and fibrosis over time using a unilateral ureteral obstruction (UUO) mouse model. Methods: Expression levels of peroxisome-related factors and ROS- and hypoxia-related genes in UUO mice were measured in a time-dependent manner. Results: UUO led to renal damage and fibrosis progression over time; it significantly increased the protein expression levels of ATG5 and ATG7, while it decreased PMP70 and PEX14 protein expression. In particular, UUO increased the protein expression level of pexophagy receptor NBR1. Although the number of peroxisomes decreased, the protein expression levels of peroxisomal biogenesis-related proteins such as PEX11b, PEX16, and PEX19 remained constant. Decreased lipid metabolism due to reductions in ACOX1, DBP, and catalase caused by UUO and increased ROS production through peroxisomal degradation and mitochondrial antioxidant enzyme dysfunction were observed. Additionally, HIF-1α protein levels gradually increased in the UUO mice, whereas those of HIF-2α initially increased and then decreased. Conclusions: UUO is characterized by a progressive, chronological reduction in peroxisomal markers. Our findings indicate that peroxisomal degradation and associated metabolic dysfunction are tightly correlated with the progression of kidney injury and fibrosis, suggesting a potential involvement of compromised peroxisomal homeostasis in renal pathogenesis rather than proving a direct causal mechanism. Maintaining peroxisomal quality control may nevertheless represent a potential therapeutic avenue for chronic kidney disease. Full article

Discoidin domain receptor 1 (DDR1) has been implicated in fibrotic progression in multiple organs, including the kidney. However, its role in regulating cytoskeletal organization and matrix remodeling in renal fibroblasts remains unclear. Here, we investigated how DDR1 expression is regulated by profibrotic stimulation and extracellular matrix stiffness, and how DDR1 influences cytoskeletal organization and collagen remodeling. Single-cell RNA sequencing of murine kidneys subjected to unilateral ureteral obstruction (UUO) revealed enrichment of Ddr1 expression in transitional fibroblast populations during early activation. In vitro, transforming growth factor-β1 (TGF-β1) increased DDR1 expression, but DDR1 depletion did not affect canonical myofibroblast marker expression. Instead, DDR1 depletion suppressed stress fiber assembly while promoting actin-rich podosome formation associated with matrix degradation. Functionally, DDR1-deficient cells exhibited impaired focal adhesion maturation, enhanced collagen degradation, reduced gel contraction, and decreased collagen matrix stiffness as measured by atomic force microscopy. Furthermore, extracellular matrix stiffness dynamically regulated DDR1 expression, suggesting a bidirectional relationship between DDR1 expression and matrix mechanics. Together, these findings identify DDR1 as a modulator of cytoskeletal remodeling that governs the balance between matrix-degradation and contractile remodeling programs in renal fibroblasts. Full article

Chronic kidney disease (CKD) represents a considerable health burden for both humans and veterinary patients globally. Renal fibrosis is the final common pathway for the progression of CKD to end-stage renal disease, which can eventually lead to renal failure. Thymoquinone (TQ), the primary bioactive constituent of Nigella sativa, has demonstrated significant antifibrotic potential; however, the specific molecular mechanisms underlying its renoprotective effects remain incompletely elucidated. This study aimed to investigate how TQ alleviates renal fibrosis to support its potential as a therapeutic agent. TQ’s renoprotective effects were evaluated in a murine unilateral ureteral obstruction (UUO) model using histopathology, Western blotting, immunofluorescence, and RT-qPCR. Network pharmacology and untargeted metabolomics were integrated to identify key pathways, which were further assessed through in vivo and in vitro experiments. TQ treatment attenuated UUO-induced renal interstitial injury. TQ treatment downregulated α-smooth muscle actin (α-SMA) and fibronectin, thereby suppressing myofibroblast activation and extracellular matrix (ECM) accumulation. Integrated multi-omics analyses indicated that the antifibrotic activity of TQ is associated with modulation of the PI3K/AKT signaling axis. Subsequent in vivo and in vitro studies suggested that TQ protects against renal injury by inhibiting aberrant PI3K/AKT signaling. This study found that TQ ameliorates renal interstitial fibrosis in UUO mice. The underlying mechanism appears to involve suppression of myofibroblast activation and ECM accumulation via inhibition of PI3K/AKT signaling. These findings highlight the therapeutic potential of TQ for renal fibrosis. Full article

Background/Objectives: Phillygenin (PHI), a natural lignan derived from Forsythia suspensa, has garnered attention for its potential to alleviate chronic diseases, including chronic colitis, pulmonary fibrosis, and diabetes. Chronic kidney disease (CKD) poses a global health challenge, characterized by high morbidity and mortality rates and associated with a spectrum of secondary complications. In this study, we aim to investigate the therapeutic effectiveness of PHI on CKD and also identify molecular signals by using a unilateral ureteral obstruction (UUO) mouse model and in vitro experiments. Methods: C57BL/6 mice were administered PHI at 50 mg/kg/day to assess its therapeutic effectiveness. In vitro, lipopolysaccharide (LPS) and adenosine triphosphate (ATP) were used to induce pyroptosis, also known as pyroptosis, in renal proximal tubular cells (NRK52E). Results: After PHI treatment for 14 consecutive days, the collagen deposition and extracellular matrix (ECM) accumulation, the expression of oxidative stress response proteins (catalase, superoxide dismutase 2, NADPH oxidase 4, and thioredoxin reductase 1), pro-inflammatory markers (TNF-α and Cyclooxygenase-2(COX-2), and infiltration of neutrophils and macrophages were significantly ameliorated in the UUO mice. Interestingly, the pyroptosis-related proteins (NLRP3/Caspase-1/GSDMD/IL-1β) and cell apoptotic death were also conspicuously relieved after treatment with PHI. Furthermore, PHI administration significantly attenuated the ATP/LPS-induced NF-κB/NLRP3/Caspase-1/GSDMD pyroptosis signal pathway in NRK52E cells. Conclusions: These results demonstrate, for the first time, that PHI treatment ameliorates inflammation and the related pyroptosis via inhibitory regulation of the NF-κB/NLRP3/Caspase-1/GSDMD axis, leading to attenuated renal fibrosis and progressive CKD in UUO mice and in vitro. Our findings suggest that PHI could be a nutraceutical candidate for attenuating CKD progression. Full article

Kidney disease, be it acute or chronic, has a complex pathology and is a significant human health problem. Increasing interest has been focused on exploring therapeutic targets that can be used to safeguard kidney function under a variety of detrimental conditions. In this article, we review the protective effects of 5-methoxytryptophan (5-MTP), a tryptophan metabolite, on kidney injury. Published studies indicate that serum 5-MTP level is decreased in patients with chronic kidney disease (CKD), suggesting that 5-MTP is a biomarker for CKD and has therapeutic values. Indeed, rodent models of kidney injury induced by folic acid, lipopolysaccharide (LPS), unilateral ureteral obstruction (UUO), and ischemia/reperfusion all demonstrate that exogenous 5-MTP exhibits nephroprotective effects. The underlying mechanisms involve antioxidative damage via activating antioxidant systems such as heme oxygenase-1, anti-inflammation, anti-fibrosis, and enhanced mitophagy. To further explore the underlying mechanisms and the potential of 5-MTP as a kidney therapeutic compound, future studies need to include more rodent models of kidney injury induced by a variety of insults. Moreover, how to boost endogenous 5-MTP content and its potential synergistic effects with other therapeutic approaches aiming to combat kidney diseases also remain to be explored. Full article

Background/Objectives: To explore the protective effects of 7-Ketolithocholic acid (7-KLCA) against renal fibrosis and its mechanism, focusing on its interaction with farnesoid X receptor (FXR). Methods: In vitro, TGF-β-induced fibrosis in HK-2/NRK-49F cells and LPS-induced inflammation in HK-2 cells were detected by CCK-8, Western blot, and qPCR. In vivo, unilateral ureteral obstruction (UUO) and adenine (Ade)-induced mouse models were treated with a low/high-dose 7-KLCA or losartan. Renal injury was evaluated via H&E/Masson staining, serum creatinine (SCR), and blood urea nitrogen (BUN) levels. The 7-KLCA-FXR interaction was verified by molecular docking, CETSA, and DARTS. FXR downstream genes and related proteins were measured by WB and qPCR. Results: 7-KLCA inhibited the expression of fibrotic proteins (fibronectin, collagen-I) and reduced the LPS-induced release of inflammatory factors (IL-1β, IL-6). In mice, it alleviated renal swelling, collagen deposition, and tubular damage, while lowering serum SCR and BUN levels. Mechanistically, 7-KLCA stably bound to the FXR ligand-binding domain, enhanced its thermal stability and degradation resistance. It upregulated FXR and its downstream genes SHP and FGF15, thereby inhibiting the activation of TGF-β/Smad and Wnt/β-catenin pathways. Conclusions: This is the first study to clarify the molecular mechanism through which 7-KLCA targets FXR and dually suppresses the key pro-fibrotic pathways TGF-β/Smad and Wnt/β-catenin, thereby exerting anti-renal fibrosis effects. Full article

Background: G2/M cell cycle arrest of proximal tubular epithelial cells following acute kidney injury results in maladaptive repair and promotes chronic kidney disease. We investigated whether erythropoiesis-stimulating agents (ESA) regulate G2/M arrest and mitigate kidney fibrosis. Methods: Human kidney 2 (HK-2) cells were stimulated with TGF-β or paclitaxel, treated with darbepoetin alfa (DARB) at 0.5 ug/mL or 5 ug/mL, and cell cycles were analyzed using flow cytometry. In vivo experiments involved intraperitoneal administration of DARB (0.5 or 5 ug/kg) to the unilateral ureteral obstruction (UUO) mouse model on post-operative days three and seven. Kidney fibrosis and cell cycle regulatory proteins were analyzed using immunohistochemistry, RT-PCR, and immunoblotting. The effect of DARB on kidney fibrosis was compared with that of a p53 inhibitor. Results: In HK-2 cells treated with TGF-β or paclitaxel, G2/M cell cycle regulatory proteins were upregulated; however, this effect was reversed by DARB treatment. Immunostaining for p53 and Ki-67 indicated that the proliferative and fibrotic activities observed in TGF-β-treated HK-2 cells were mitigated by DARB treatment. Histological analysis of UUO mice using F4/80 staining and TUNEL assay showed that DARB treatment reduced inflammatory cell infiltration and apoptotic cell accumulation. Additionally, fibrotic changes assessed by Masson’s trichrome, Sirius red, and PAS staining confirmed the antifibrotic effects of DARB treatment in UUO mice, independent of changes in hemoglobin levels, suggesting a mechanism distinct from its hematopoietic effects. DARB reduced fibrosis-related markers by suppressing G2/M cell cycle regulatory markers and inhibited the JNK and p38-MAPK signaling pathways, which play key roles in kidney fibrosis in TGF-β-treated HK-2 cells and UUO mice. Finally, DARB treatment demonstrated an anti-fibrotic effect in HK-2 cells stimulated with TGF-β or paclitaxel, comparable to that of a p53 inhibitor. Conclusions: DARB treatment decreased G2/M cell phase arrest and attenuated kidney fibrosis, suggesting a new renoprotective mechanism for ESA. Full article

Obstructive nephropathy is a common clinical condition caused by urinary retention. After urine flow is restored, kidney function is recovered. However, the effectiveness of this process can be influenced by many factors, including the age of the patient. In this study, we analyzed the following parameters in young and old rats subjected to a 3-day reversible unilateral ureteral obstruction (R-UUO): AKI severity, renal tissue proliferation and histology, inflammatory and fibrosis marker expression, as well as autophagosomal-lysosomal and mitochondrial function. Compared to old rats, young animals exhibited more pronounced renal tissue proliferation and higher expression of profibrotic markers (Col1a1, Fn1, Tgfb1, MMP2), but diminished expression of pro-inflammatory markers (Il1b, Tnfa, Cd32) in response to R-UUO. Additionally, young rats showed more pronounced activity of autophagy, as indicated by increased beclin-1 levels. R-UUO induced severe damage to the mitochondrial respiratory chain in old animals, as indicated by reduced complex I, IV, cytochrome c, VDAC protein levels, and impaired mitochondrial biogenesis (associated with decreased Pgc1a mRNA expression). Thus, we demonstrated that despite restored urine outflow, kidneys exhibited autophagy activation, inflammatory response, and mitochondrial dysfunction after R-UUO. Negative alterations in the kidney were age-dependent indicating necessity for therapeutic strategies optimization for patients of different ages. Full article

Calcium oxalate (CaOx) stones account for 90% of uroliths in cats and contribute to ureteral inflammation and fibrosis, although the underlying mechanism remains unclear. Apoptosis inhibitor of macrophage (AIM) is known to play a protective role against tubular injury in feline kidney disease. This study investigated whether AIM contributes to ureteral fibrosis by using AIM-felinized mice subjected to CaOx bead-induced ureteral injury. Male C57BL/6 mice (n = 54), including wild-type mice (mA), AIM-knockout (koA) mice, and AIM-felinized mice (fA), were assigned to either a unilateral ureteral obstruction (UUO; U) group or a UUO plus CaOx implantation (C) group. Ureters were collected 14 days after the procedure for histopathological analysis. The severity of ureteral injury followed the order of koA-C ≥ fA-C > mA-C, indicating AIM’s involvement in the injury process. Furthermore, fA exhibited more severe fibrosis than mA mice (p < 0.05), suggesting that mouse AIM may have stronger anti-fibrotic effects than feline AIM. These results suggest that AIM-felinized mice could serve as a useful model for investigating feline-specific ureteral pathology. To our knowledge, this is the first experimental study to explore the role of feline AIM in ureteral injury and fibrosis. Further studies are warranted to validate the utility of this model. Full article

Renocardiac syndrome type 4 (RCS4) is a common comorbid pathology, but the mechanisms of kidney dysfunction-induced cardiac remodeling and the involvement of cardiac progenitor cells (CPCs) in this process remain unclear. The aim of this study was to investigate the structural and functional changes in the cardiac muscle in RCS4 induced by unilateral ureteral obstruction (UUO) and the role of nestin⁺ CPCs in these. Heart function and localization of nestin⁺ cells in the myocardium were assessed using nestin-GFP transgenic mice subjected to UUO for 14 and 28 days. UUO resulted in cardiac hypertrophy, accompanied by an elongation of the QRS wave on the ECG, decreased expression of Cxcl1, Cxcl9, and Il1b, reduced the number of CD11b⁺ cells, and increased in titin isoform parameters, such as T1/MHC and TT/MHC ratios, without changes in fibrosis markers. The number of nestin⁺ cells increased in the myocardium with increased duration of UUO and displayed an SCA-1⁺TBX5⁺ phenotype, consistent with CPCs. Thus, cardiac pathology in RCS4 was manifested by cardiomyocyte hypertrophy with changes in the electrophysiological phenotype of the heart, not accompanied by fibrosis or inflammation. Nestin⁺ cardiac cells retained the CPC phenotype during UUO, and their number increased, which suggests their participation in regenerative processes in the heart. Full article

Background: Chronic kidney disease (CKD) is a global health problem marked by a persistent deterioration in the function of the nephrons and kidneys. To identify novel therapies for CKD, we investigated the molecular targets associated with the initiation and progression of the disease. Methods: The transcriptional profile dataset of GSE42303 was downloaded from GEO (The Gene Expression Omnibus). Utilizing the R package limma, the differentially expressed genes (DEGs) were identified between control (Con) and unilateral ureteral obstruction (UUO) mice. Then, functional enrichment, protein–protein interactions (PPI) and subsequent hub genes were identified by multiple bioinformatics approaches. Further validations of these hub genes were confirmed through the GSE118339 dataset and in vivo experiments. Results: We found 381 DEGs between Con and UUO mice (308 up-regulated genes and 73 down-regulated genes). GO functions and pathway analysis indicated that DEGs were mainly enriched in activities associated with inflammation and fibrosis. The mRNA expressions of nine hub genes were identified and confirmed by dataset GSE118339 and in vivo experiments. Conclusions: The hub genes Fgg, Penk, Ckap4, and Gpc3 may be new prospective targets for the treatment of the initiation and progression of CKD. Full article

In chronic kidney disease (CKD) research, animal models such as the unilateral ureteral obstruction (UUO) rodent model are crucial to understanding disease progression, particularly renal fibrosis. Despite its widespread use, the molecular mechanisms driving CKD remain incompletely understood. Given the interplay between metabolism and fibrosis, a comprehensive metabolomic analysis of UUO renal tissue is necessary. This study involved untargeted multiplatform analysis using liquid chromatography (LC), gas chromatography (GC), and capillary electrophoresis (CE) coupled with mass spectrometry (MS) to examine murine kidney tissue from the UUO model. The results highlight metabolic changes associated with tubulointerstitial fibrosis, which affect pathways such as the tricarboxylic acid (TCA) cycle, the urea cycle, and lipid metabolism. In particular, fibrosis impacts the lipidomic profile, with decreases in most lipid classes and increases in specific glycerophospholipids, hexosylceramides, and cholesterol esters. These findings demonstrate the value of a multiplatform approach in elucidating metabolic alterations in CKD, providing information on the underlying molecular mechanisms and paving the way for further research. Full article

Obstructive nephropathy (ON), characterized by urine flow disruption, can induce chronic kidney disease (CKD). Although the release of the obstruction is performed as the primary intervention, renal pathology often persists and progresses. Accordingly, the murine model of releasing unilateral ureteral obstruction (RUUO) is valuable for investigating the molecular events underlying renal damage after obstruction release. Remarkably, after RUUO, disturbances such as oxidative stress, inflammation, lipid accumulation, and fibrosis continue to increase. Mitochondrial dysfunction contributes to fibrosis in the UUO model, but its role in RUUO remains unclear. Additionally, the impact of using antioxidants to restore mitochondrial function and prevent renal fibrosis in RUUO has not been determined. This study aimed to determine the therapeutic effect of pre-administering the antioxidant sulforaphane (SFN) in the RUUO model. SFN was administered 1 day before RUUO to evaluate mitochondrial biogenesis, fatty acids (FA) metabolism, bioenergetics, dynamics, and mitophagy/autophagy mechanisms in the kidney. Our data demonstrated that SFN enhanced mitochondrial biogenesis and reestablished mitochondrial oxygen consumption and β-oxidation. These effects collectively reduced lipid accumulation and normalized mitochondrial dynamics, mitophagy, and autophagy, thereby mitigating fibrosis after obstruction. Our findings suggest that SFN holds promise as a potential therapeutic agent in ON-induced CKD progression in RUUO and opens new avenues in studying antioxidant molecules to treat this disease. Full article

Chronic kidney disease (CKD) progresses through mechanisms involving inflammation, fibrosis, and oxidative stress, leading to the gradual structural and functional deterioration of the kidneys. Tormentic acid (TA), a triterpenoid compound with known anti-inflammatory and antioxidant properties, shows significant potential in counteracting these pathological processes. This study explored the protective role of TA in a unilateral ureteral obstruction (UUO)-induced CKD model. Mice received TA through intraperitoneal injections at a dosage of 5 mg/kg per day for 8 consecutive days, commencing a day before the UUO procedure. The TA treatment significantly improved both structural and functional kidney injury. It suppressed cytokine expression and reduced immune cell infiltration, inhibited the activation of the mitogen-activated protein kinase cascade, and alleviated endoplasmic reticulum stress. Moreover, TA displayed potent anti-fibrotic effects by reversing epithelial-to-mesenchymal transition and inhibiting Smad2/3 activation, reducing extracellular matrix deposition. TA also mitigated oxidative stress by attenuating lipid peroxidation and boosting antioxidant defenses. Additionally, it inhibited apoptosis and ferroptosis by reducing oxidative stress and modulating key cell death markers. Collectively, these findings indicate that TA provides comprehensive renoprotection in the UUO model by effectively targeting inflammation, fibrosis, oxidative stress, and tubular cell death in CKD progression. Full article

Kidney fibrosis is the common pathological pathway in progressive chronic kidney disease (CKD), and current treatments are largely ineffective. The C-X-C chemokine receptor 4 (CXCR4) is crucial to fibrosis development. By using neural cell adhesion molecules as scaffolds with binding loops that mimic the shape of shark antibodies, fully humanized single-domain i-bodies have been developed. The first-generation i-body, AD-114, demonstrated antifibrotic effects in a mouse model of folic acid (FA)-induced renal fibrosis. The second-generation i-body, AD-214, is an Fc-fusion protein with an extended half-life, enhanced activity, and a mutated Fc domain to prevent immune activation. To investigate the renoprotective mechanisms of AD-214, RPTEC/TERT1 cells (a human proximal tubular cell line) were incubated with TGF-b1 with/without AD-214 and the supernatant was collected to measure collagen levels by Western blot. Mice with unilateral ureteral obstruction (UUO) received AD-214 intraperitoneally (i.p.) every two days for 14 days. Kidney fibrosis markers and kidney function were then analyzed. AD-214 suppressed TGF-b1-induced collagen overexpression in RPTEC/TERT1 cells. In UUO mice, AD-214 reduced extracellular matrix (ECM) deposition, restored kidney function, and limited leukocyte infiltration. In a scratch assay, AD-214 also inhibited macrophage migration. To conclude, i-body AD-214 attenuates UUO-induced kidney fibrosis by inhibiting leukocyte infiltration and macrophage migration. Full article