ELABELA-derived peptide ELA13 attenuates kidney fibrosis by inhibiting the Smad and ERK signaling pathways. / ELABELA衍生肽ELA13通过抑制Smad和ERK信号通路减轻肾纤维化.

Kidney fibrosis is an inevitable result of various chronic kidney diseases (CKDs) and significantly contributes to end-stage renal failure. Currently, there is no specific treatment available for renal fibrosis. ELA13 (amino acid sequence: RRCMPLHSRVPFP) is a conserved region of ELABELA in all vertebrates; however, its biological activity has been very little studied. In the present study, we evaluated the therapeutic effect of ELA13 on transforming growth factor-ß1 (TGF-ß1)-treated NRK-52E cells and unilateral ureteral occlusion (UUO) mice. Our results demonstrated that ELA13 could improve renal function by reducing creatinine and urea nitrogen content in serum, and reduce the expression of fibrosis biomarkers confirmed by Masson staining, immunohistochemistry, real-time polymerase chain reaction (RT-PCR), and western blot. Inflammation biomarkers were increased after UUO and decreased by administration of ELA13. Furthermore, we found that the levels of essential molecules in the mothers against decapentaplegic (Smad) and extracellular signal-regulated kinase (ERK) pathways were reduced by ELA13 treatment in vivo and in vitro. In conclusion, ELA13 protected against kidney fibrosis through inhibiting the Smad and ERK signaling pathways and could thus be a promising candidate for anti-renal fibrosis treatment.

Attenuating Renal Interstitial Fibrosis by Shenqi Pill via Reducing Inflammation Response Regulated by NF-κB Pathway In Vitro and In Vivo.

INTRODUCTION: One of the most significant clinical features of chronic  kidney disease is renal interstitial fibrosis (RIF). This study aimed  to investigate the role and mechanism of Shenqi Pill (SQP) on RIF. METHODS: RIF model was established by conducting unilateral  ureteral obstruction (UUO) surgery on rat or stimulating human  kidney-2 (HK-2) cell with transforming growth factor ß1 (TGFß1).  After modeling, the rats in the SQP low dose group (SQP-L), SQP  middle dose group (SQP-M) and SQP high dose group (SQP-H)  were treated with SQP at 1.5, 3 or 6 g/kg/d, and the cells in the  TGFß1+SQP-L/M/H were treated with 2.5%, 5%, 10% SQP-containing  serum. In in vivo assays, serum creatinine (SCr) and blood urea  nitrogen (BUN) content were measured, kidney histopathology  was evaluated., and α-smooth muscle actin (α-SMA) expression  was detected by immunohistochemistry. Interleukin-1ß (IL-1ß),  interleukin-6 (IL-6) and tumor necrosis factor-α (TNF-α) content,  inhibitor of kappa B alpha (IKBα) and P65 phosphorylation were  assessed. Meanwhile, cell viability, inflammatory cytokines content,  α-SMA expression, IKBα and P65 phosphorylation were detected  in vitro experiment.  Results. SQP exhibited reno-protective effect by decreasing SCr  and BUN content, improving renal interstitial damage, blunting  fibronectin (FN) and α-SMA expression in RIF rats. Similarly, after  the treatment with SQP-containing serum, viability and α-SMA  expression were remarkably decreased in TGFß1-stimulated HK-2  cell. Furthermore, SQP markedly down-regulated IL-1ß, IL-6, and  TNF-α content, IKBα and RelA (P65) phosphorylation both in vivo and in vitro.  Conclusion. SQP has a reno-protective effect against RIF in vivo and in vitro, and the effect is partly linked to nuclear factor-kappa  B (NF-κB) pathway related inflammatory response, which indicates  that SQP may be a candidate drug for RIF. DOI: 10.52547/ijkd.7546.

Beclin-1-Derived Peptide MP1 Attenuates Renal Fibrosis by Inhibiting the Wnt/ß-Catenin Pathway.

Renal fibrosis is distinguished by the abnormal deposition of extracellular matrix and progressive loss of nephron function, with a lack of effective treatment options in clinical practice. In this study, we discovered that the Beclin-1-derived peptide MP1 significantly inhibits the abnormal expression of fibrosis and epithelial-mesenchymal transition-related markers, including α-smooth muscle actin, fibronectin, collagen I, matrix metallopeptidase 2, Snail1, and vimentin both in vitro and in vivo. H&E staining was employed to evaluate renal function, while serum creatinine (Scr) and blood urea nitrogen (BUN) were used as main indices to assess pathologic changes in the obstructed kidney. The results demonstrated that daily treatment with MP1 during the 14-day experiment significantly alleviated renal dysfunction and changes in Scr and BUN in mice with unilateral ureteral obstruction. Mechanistic research revealed that MP1 was found to have a significant inhibitory effect on the expression of crucial components involved in both the Wnt/ß-catenin and transforming growth factor (TGF)-ß/Smad pathways, including ß-catenin, C-Myc, cyclin D1, TGF-ß1, and p-Smad/Smad. However, MP1 exhibited no significant impact on either the LC3II/LC3I ratio or P62 levels. These findings indicate that MP1 improves renal physiologic function and mitigates the fibrosis progression by inhibiting the Wnt/ß-catenin pathway. Our study suggests that MP1 represents a promising and novel candidate drug precursor for the treatment of renal fibrosis. SIGNIFICANCE STATEMENT: This study indicated that the Beclin-1-derived peptide MP1 effectively mitigated renal fibrosis induced by unilateral ureteral obstruction through inhibiting the Wnt/ß-catenin pathway and transforming growth factor-ß/Smad pathway, thereby improving renal physiological function. Importantly, unlike other Beclin-1-derived peptides, MP1 exhibited no significant impact on autophagy in normal cells. MP1 represents a promising and novel candidate drug precursor for the treatment of renal fibrosis focusing on Beclin-1 derivatives and Wnt/ß-catenin pathway.

Forsythiaside A suppresses renal fibrosis and partial epithelial-mesenchymal transition by targeting THBS1 through the PI3K/AKT signaling pathway.

Renal fibrosis is a key feature of chronic kidney disease (CKD) progression, whereas no proven effective anti-fibrotic treatments. Forsythiaside A (FTA), derived from Forsythia suspense, has been found to possess nephroprotective properties. However, there is limited research on its anti-fibrotic effects, and its mechanism of action remains unknown. This study aimed to investigate the suppressive effects of FTA on renal fibrosis and explore the underlying mechanisms. In vitro, we established a HK2 cell model induced by transforming growth factor ß1 (TGF-ß1), and in vivo, we used a mice model induced by unilateral ureteral obstruction (UUO). CCK-8 assay, qRT-PCR, Western blotting, immunofluorescence, flow cytometry, histological staining, immunohistochemistry, TUNEL assay, RNA transcriptome sequencing, and molecular docking were performed. The results showed that FTA (40 µM or 80 µM) treatment improved cell viability and suppressed TGF-ß1-induced fibrotic changes and partial epithelial-mesenchymal transition (EMT). Furthermore, FTA treatment reversed the activation of the PI3K/AKT signaling pathway, and THBS1 was identified as the target gene. We found that THBS1 knockdown suppressed the activation of the PI3K/AKT signaling pathway and reduced the fibrosis and partial EMT-related protein level. Conversely, THBS1 overexpression activated the PI3K/AKT signaling pathway and exacerbated renal fibrosis and partial EMT. In vivo, mice were administered FTA (30 or 60 mg/kg) for 2 weeks, and the results demonstrated that FTA administration significantly mitigated tubular injury, tubulointerstitial fibrosis, partial EMT, and apoptosis. In conclusion, FTA inhibited renal fibrosis and partial EMT by targeting THBS1 and inhibiting activation of the PI3K/AKT pathway.

Vildagliptin Treatment Ameliorates Renal Interstitial Fibrosis in a Murine Model of Unilateral Ureteral Obstruction.

Renal interstitial fibrosis in mice can be modeled using unilateral ureteral obstruction (UUO). Here, we investigated the anti-fibrotic effects of the dipeptidyl peptidase-4 inhibitor vildagliptin in this model. We found that vildagliptin given in the drinking water at 10.6 ± 1.5 mg/kg/d prevented fibrosis. Mechanistically, UUO was associated with extracellular signal-regulated kinase (ERK) phosphorylation and with the accumulation of the toxic lipid peroxidation product expression of 4-hydroxy-2-nonenal (4-HNE). Both were significantly inhibited by vildagliptin. Similarly, UUO caused reductions in heme oxygenase-1 (HO-1) mRNA in the kidney, whereas interleukin-6 (IL-6) and cyclooxygenase-1 (COX-1) mRNA were increased; these effects were also prevented by vildagliptin. Taking these data together, we propose that vildagliptin reduces renal interstitial fibrosis resulting from UUO by means of its effects on ERK phosphorylation and the amounts of 4-HNE, HO-1, IL-6 and COX-1 in the kidney.

Alantolactone Attenuates Renal Fibrosis via Inhibition of Transforming Growth Factor ß/Smad3 Signaling Pathway.

BACKGRUOUND: Renal fibrosis is characterized by the accumulation of extracellular matrix proteins and interstitial fibrosis. Alantolactone is known to exert anticancer, anti-inflammatory, antimicrobial and antifungal effects; however, its effects on renal fibrosis remains unknown. Here, we investigated whether alantolactone attenuates renal fibrosis in mice unilateral ureteral obstruction (UUO) and evaluated the effect of alantolactone on transforming growth factor (TGF) signaling pathway in renal cells. METHODS: To evaluate the therapeutic effect of alantolactone, cell counting kit-8 (CCK-8) assay, histological staining, Western blot analysis, and real-time quantitative polymerase chain reaction were performed in UUO kidneys in vivo and in TGF-ß-treated renal cells in vitro. RESULTS: Alantolactone (0.25 to 4 µM) did not affect the viability of renal cells. Mice orally administered 5 mg/kg of alantolactone daily for 15 days did not show mortality or liver toxicity. Alantolactone decreased UUO-induced blood urea nitrogen and serum creatinine levels. In addition, it significantly alleviated renal tubulointerstitial damage and fibrosis and decreased collagen type I, fibronectin, and α-smooth muscle actin (α-SMA) expression in UUO kidneys. In NRK-49F cells, alantolactone inhibited TGF-ßstimulated expression of fibronectin, collagen type I, plasminogen activator inhibitor-1 (PAI-1), and α-SMA. In HK-2 cells, alantolactone inhibited TGF-ß-stimulated expression of collagen type I and PAI-1. Alantolactone inhibited UUO-induced phosphorylation of Smad3 in UUO kidneys. In addition, it not only decreased TGF-ß secretion but also Smad3 phosphorylation and translocation to nucleus in both kidney cell lines. CONCLUSION: Alantolactone improves renal fibrosis by inhibiting the TGF-ß/Smad3 signaling pathway in obstructive nephropathy. Thus, alantolactone is a potential therapeutic agent for chronic kidney disease.

Reno-protective effect of protocatechuic acid is independent of sex-related differences in murine model of UUO-induced kidney injury.

BACKGROUND: Obstructive nephropathy is a condition often caused by urinary tract obstruction either anatomical (e.g., tumors), mechanical (e.g., urolithiasis), or compression (e.g., pregnancy) and can progress to chronic kidney disease (CKD). Studies have shown sexual dimorphism in CKD, where males were found to have a more rapid decline in kidney function following kidney injury compared to age-matched females. Protocatechuic acid (PCA), an anti-oxidant and anti-inflammatory polyphenolic compound, has demonstrated promising effects in mitigating drug-induced kidney injuries. The current study aims to explore sexual dimorphism in kidney injury after unilateral ureteral obstruction (UUO) and assess whether PCA treatment can mitigate kidney injury in both sexes. METHODS: UUO was induced in 10-12 weeks old male and female C57BL/6J mice. Mice were categorized into four groups (n = 6-8/group); Sham, Sham plus PCA (100 mg/kg, I.P daily), UUO, and UUO plus PCA. RESULTS: After 2 weeks of induction of UUO, markers of kidney oxidative stress (TBARs), inflammation (IL-1α and IL-6), tubular injury (neutrophil gelatinase-associated lipocalin, NGAL and urinary kidney injury molecule-1, KIM-1), fibrosis (Masson's trichrome staining, collagen IV expression, MMP-2 and MMP-9) and apoptosis (TUNEL+ cells, active caspase-1 and caspase-3) were significantly elevated in both males and females relative to their sham counterparts. Males exhibited significantly greater kidney oxidative stress, inflammation, fibrosis, and apoptosis after induction of UUO when compared to females. PCA treatment significantly attenuated UUO-induced kidney injury, inflammation, fibrosis, and apoptosis in both sexes. CONCLUSION: Our findings suggest a differential gender response to UUO-induced kidney injury with males being more sensitive to UUO-induced kidney inflammation, fibrosis, and apoptosis than age-matched females. Importantly, PCA treatment reduced UUO-induced kidney injury in a sex-independent manner which might be attributed to its anti-oxidant, anti-inflammatory, anti-fibrotic, and anti-apoptotic properties.

Sulforaphane protects from kidney damage during the release of unilateral ureteral obstruction (RUUO) by activating nuclear factor erythroid 2-related factor 2 (Nrf2): Role of antioxidant, anti-inflammatory, and antiapoptotic mechanisms.

Releasing unilateral ureteral obstruction (RUUO) is the gold standard for decreasing renal damage induced during unilateral ureteral obstruction (UUO); however, the complete recovery after RUUO depends on factors such as the time and severity of obstruction and kidney contralateral compensatory mechanisms. Interestingly, previous studies have shown that kidney damage markers such as oxidative stress, inflammation, and apoptosis are present and even increase after removal obstruction. To date, previous therapeutic strategies have been used to potentiate the recovery of renal function after RUUO; however, the mechanisms involving renal damage reduction are poorly described and sometimes focus on the recovery of renal functionality. Furthermore, using natural antioxidants has not been completely studied in the RUUO model. In this study, we selected sulforaphane (SFN) because it activates the nuclear factor erythroid 2-related factor 2 (Nrf2), a transcription factor that induces an antioxidant response, decreasing oxidative stress and inflammation, preventing apoptosis. Thus, we pre-administrated SFN on the second day after UUO until day five, where we released the obstruction on the three days after UUO. Then, we assessed oxidative stress, inflammation, and apoptosis markers. Interestingly, we found that SFN administration in the RUUO model activated Nrf2, inducing its translocation to the nucleus to activate its target proteins. Thus, the Nrf2 activation upregulated glutathione (GSH) content and the antioxidant enzymes catalase, glutathione peroxidase (GPx), and glutathione reductase (GR), which reduced the oxidative stress markers. Moreover, the improvement of antioxidant response by SFN restored S-glutathionylation in the mitochondrial fraction. Activated Nrf2 also reduced inflammation by lessening the nucleotide-binding domain-like receptor family pyrin domain containing 3 and interleukin 1ß (IL-1ß) production. Reducing oxidative stress and inflammation prevented apoptosis by avoiding caspase 3 cleavage and increasing B-cell lymphoma 2 (Bcl2) levels. Taken together, the obtained results in our study showed that the upregulation of Nrf2 by SFN decreases oxidative stress, preventing inflammation and apoptosis cell death during the release of UUO.

Asperulosidic Acid Ameliorates Renal Interstitial Fibrosis via Removing Indoxyl Sulfate by Up-Regulating Organic Anion Transporters in a Unilateral Ureteral Obstruction Mice Model.

Asperulosidic acid is a bioactive iridoid isolated from Hedyotis diffusa Willd. with anti-inflammatory and renal protective effects. However, its mechanism on renal interstitial fibrosis has not been elucidated yet. The present study aims to explore whether asperulosidic acid could retard renal fibrosis by reducing the circulating indoxyl sulfate (IS), which is a uremic toxin and accelerates chronic kidney disease progression by inducing renal fibrosis. In this paper, a unilateral ureteral obstruction (UUO) model of Balb/C mice was established. After the mice were orally administered with asperulosidic acid (14 and 28 mg/kg) for two weeks, blood, liver and kidney were collected for biochemical, histological, qPCR and Western blot analyses. Asperulosidic acid administration markedly reduced the serum IS level and significantly alleviated the histological changes in glomerular sclerosis and renal interstitial fibrosis. It is noteworthy that the mRNA and protein levels of the organic anion transporter 1 (OAT1), OAT3 and hepatocyte nuclear factor 1α (HNF1α) in the kidney were significantly increased, while the mRNA expressions of cytochrome P450 2e1 (Cyp2e1) and sulfotransferase 1a1 (Sult1a1) in the liver were not altered after asperulosidic acid administration. These results reveal that asperulosidic acid could accelerate the renal excretion of IS by up-regulating OATs via HNF1α in UUO mice, thereby alleviating renal fibrosis, but did not significantly affect its production in the liver, which might provide important information for the development of asperulosidic acid.

Vitexin attenuates chronic kidney disease by inhibiting renal tubular epithelial cell ferroptosis via NRF2 activation.

BACKGROUND: Chronic kidney disease (CKD) involves a variety of pathological processes, and ferroptosis plays a vital role in CKD progression. Targeting ferroptosis is a promising strategy for the treatment of CKD. However, inhibitors of ferroptosis have not been used in the clinical treatment of CKD. Vitexin is a natural flavonoid with many biological activities and protective effects against various diseases. However, whether vitexin can prevent the progression of CKD is not known. METHODS: In vivo, the effect of vitexin on CKD was evaluated by using mouse models of unilateral ureteral obstruction (UUO) and unilateral ischemia-reperfusion (UIR). Western blotting, Sirius red staining and transmission electron microscopy were used to analyze renal tubular injury, interstitial fibrosis, and inflammation in the kidneys of UUO and UIR mice. In vitro, CCK8 assays and lipid peroxidation assays were performed to analyze cell viability and lipid peroxidation in human renal tubular epithelial cells (HK2 cells) induced by erastin. The activation of renal fibroblasts (NRK-49 F cells) was also analyzed. Additionally, an in-silico protein-drug docking model and coimmunoprecipitation were performed to determine the direct substrate of vitexin. RESULTS: In vivo, vitexin treatment significantly ameliorated renal tubular injury, interstitial fibrosis, and inflammation in the kidneys of UUO and UIR mice. Additionally, our results showed that vitexin significantly attenuated UUO- and UIR-induced ferroptosis in renal tubular epithelial cells by upregulating glutathione peroxidase 4 (GPX4) protein levels and inhibiting lipid peroxidation in mouse kidneys. In vitro, treatment with vitexin inhibited erastin-induced ferroptosis in HK2 cells. Moreover, vitexin inhibited the expression of collagen I and α-SMA (alpha-smooth muscle actin) in NRK-49 F cells induced by the supernatant of erastin-treated HK2 cells. Mechanistically, our results suggested that vitexin could activate the NRF2/heme oxygenase-1 (HO-1) pathway by inhibiting the KEAP1- and ubiquitination-mediated degradation of NRF2, thereby increasing the expression of GPX4, and further inhibiting lipid peroxidation and ferroptosis. Additionally, knockout of NRF2 greatly inhibited the antiferroptotic effects of vitexin. CONCLUSIONS: Taken together, our results indicate that vitexin can protect against renal tubular epithelial cell ferroptosis in CKD by activating the KEAP1/NRF2/HO-1 pathway and is a promising drug to treat CKD.

Losartan alleviates renal fibrosis by inhibiting the biomechanical stress-induced epithelial-mesenchymal transition of renal epithelial cells.

Angiotensin receptor blockers (ARBs) have been reported to be beneficial of renal fibrosis, but the molecular and cellular mechanisms are still unclear. In this study, we investigated the effectiveness and relevant mechanism of ARBs in alleviating renal fibrosis, especially by focusing on biomechanical stress-induced epithelial to mesenchymal transition (EMT) of renal epithelial cells. Unilateral ureteral obstruction (UUO) renal fibrosis model was established in mice by ligating the left ureter, and then randomly received losartan at a low dose (1 mg/kg) or a regular dose (3 mg/kg) for 2 weeks. Compared to the control, histological analysis showed that losartan treatment at either a low dose or a regular dose effectively attenuated renal fibrosis in the UUO model. To further understand the mechanism, we ex vivo loaded primary human renal epithelial cells to 50 mmHg hydrostatic pressure. Western blot and immunostaining analyses indicated that the loading to 50 mmHg hydrostatic pressure for 24 h significantly upregulated vimentin, ß-catenin and α-SMA, but downregulated E-cadherin in renal epithelial cells, suggesting the EMT. The addition of 10 or 100 nM losartan in medium effectively attenuated the EMT of renal epithelial cells induced by 50 mmHg hydrostatic pressure loading. Our in vivo and ex vivo experimental data suggest that losartan treatment, even at a low dose can effectively alleviate renal fibrosis in mouse UUO model, at least partly by inhibiting the biomechanical stress-induced EMT of renal epithelial cells. A low dose of ARBs may repurpose for renal fibrosis treatment.

Ecliptasaponin A attenuates renal fibrosis by regulating the extracellular matrix of renal tubular cells.

Renal fibrosis is the most common manifestation of end-stage renal disease (ESRD), including diabetic kidney disease (DKD), but there is no effective treatment in renal fibrosis. Natural products are a rich source of clinical drug research and have been used in the clinical research of various diseases. In this study, we searched for traditional Chinese medicine monomers that attenuate fibrosis and assessed their effect on the fibrosis marker connective tissue growth factor (CTGF) in cells which we found ecliptasaponin A. Subsequently, we evaluated the effect of ecliptasaponin A on renal fibrosis in the classic renal fibrosis unilateral ureteral obstruction (UUO) mouse model and found that ecliptasaponin A could reduce the renal collagen fiber deposition and renal extracellular matrix (ECM) protein expression in UUO mice. In vitro, ecliptasaponin A can inhibit ECM protein expression in human kidney-2 (HK-2) cells induced by transforming growth factor-beta1 (TGFß1). To further clarify the mechanism of ecliptasaponin A in attenuating renal fibrosis, we performed transcriptome sequencing of HK-2 cells treated with TGFß1 and ecliptasaponin A. The functions and pathways were mainly enriched in the extracellular matrix and TGFß signalling pathway. Matrix metalloproteinase 10 (MMP10) and matrix metalloproteinase 13 (MMP13) are the main differentially expressed genes in extracellular matrix regulation. Then, we measured MMP10 and MMP13 in the cells and found that ecliptasaponin A had a significant inhibitory effect on MMP13 expression but not on MMP10 expression. Furthermore, we overexpressed MMP13 in HK-2 cells treated with TGFß1 and found that MMP13 promoted HK-2 cell injury. Our findings suggest that ecliptasaponin A can attenuate renal fibrosis, which may provide a new method for treating renal fibrosis clinically.

Berberine ameliorates renal interstitial inflammation and fibrosis in mice with unilateral ureteral obstruction.

Berberine acts via multiple pathways to alleviate fibrosis in various tissues and shows renoprotective effects. However, its role and underlying mechanisms in renal fibrosis remain unclear. Herein, we aimed to investigate the protective effects and molecular mechanisms of berberine against unilateral ureteric obstruction-induced renal fibrosis. The results indicated that berberine treatment (50 mg/kg/day) markedly alleviated histopathological alterations, collagen deposition and inflammatory cell infiltration in kidney tissue and restored mouse renal function. Mechanistically, berberine intervention inhibited NOD-like receptor family pyrin domain-containing 3 (NLRP3) inflammasome activation and the levels of the inflammatory cytokine IL-1ß in the kidneys of unilateral ureteric obstruction mice. In addition, berberine relieved unilateral ureteric obstruction-induced renal injury by activating adenosine monophosphate-activated protein kinase (AMPK) signalling and promoting fatty acid ß-oxidation. In vitro models showed that berberine treatment prevented the TGF-ß1-induced profibrotic phenotype of hexokinase 2 (HK-2) cells, characterized by loss of an epithelial phenotype (alpha smooth muscle actin [α-SMA]) and acquisition of mesenchymal marker expression (E-cadherin), by restoring abnormal fatty acid ß-oxidation and upregulating the expression of the fatty acid ß-oxidation related-key enzymes or regulators (phosphorylated-AMPK, peroxisome proliferator activated receptor alpha [PPARα] and carnitine palmitoyltransferase 1A [CPT1A]). Collectively, berberine alleviated renal fibrosis by inhibiting NLRP3 inflammasome activation and protected tubular epithelial cells by reversing defective fatty acid ß-oxidation. Our findings might be exploited clinically to provide a potential novel therapeutic strategy for renal fibrosis.

Renal Fibrosis Is Alleviated through Targeted Inhibition of IL-11-Induced Renal Tubular Epithelial-to-Mesenchymal Transition.

Renal fibrosis is a pathologic process that leads to irreversible renal failure without effective treatment. Epithelial-to-mesenchymal transition (EMT) plays a key role in this process. The current study found that aberrant expression of IL-11 is critically involved in tubular EMT. IL-11 and its receptor subunit alpha-1 (IL-11Rα1) were significantly induced in renal tubular epithelial cells (RTECs) in unilateral ureteral obstruction (UUO) kidneys, co-localized with transforming growth factor-ß1. IL-11 knockdown ameliorated UUO-induced renal fibrosis in vivo and transforming growth factor-ß1-induced EMT in vitro. IL-11 intervention directly induced the transdifferentiation of RTECs to the mesenchymal phenotype and increased the synthesis of profibrotic mediators. The EMT response induced by IL-11 was dependent on the sequential activation of STAT3 and extracellular signal-regulated kinase 1/2 signaling pathways and the up-regulation of metadherin in RTECs. Micheliolide (MCL) competitively inhibited the binding of IL-11 with IL-11Rα1, suppressing the activation of STAT3 and extracellular signal-regulated kinase 1/2-metadherin pathways, ultimately inhibiting renal tubular EMT and interstitial fibrosis induced by IL-11. In addition, treatment with dimethylaminomicheliolide, a pro-drug of MCL for in vivo use, significantly ameliorated renal fibrosis exacerbated by IL-11 in the UUO model. These findings suggest that IL-11 is a promising target in renal fibrosis and that MCL/dimethylaminomicheliolide exerts its antifibrotic effect by suppressing IL-11/IL-11Rα1 interaction and blocking its downstream effects.

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.

Psoralen Alleviates Renal Fibrosis by Attenuating Inflammasome-Dependent NLRP3 Activation and Epithelial-Mesenchymal Transition in a Mouse Unilateral Ureteral Obstruction Model.

The role of psoralen (PS), a major active component extracted from Psoralea corylifolia L. seed, in renal fibrosis is still unclear. Thus, the objective of this study was to evaluate the effects of PS on the development and progression of renal fibrosis induced by unilateral ureteral obstruction (UUO) in a mouse model. Mice were divided into four groups: PS (20 mg/kg, i.g., n = 5), PS + sham (n = 5), UUO (n = 10), and PS + UUO (n = 10). PS was intragastrically administered 24 h before UUO and continued afterwards for 7 days. All mice were killed 7 days post UUO. Severe tubular atrophy, tubular injury, and tubulointerstitial fibrosis (TIF) were significantly developed in UUO mice. A higher expression of transforming growth factor-ß1 (TGF-ß1) was accompanied by elevated levels of α-smooth muscle actin (α-SMA) and phosphorylated Smad2/3 (pSmad2/3) at 7 days post UUO. However, PS treatment reduced tubular injury, interstitial fibrosis, and the expression levels of TGF-ß1, α-SMA, and pSmad2/3. Furthermore, the levels of macrophages (represented by F4/80 positive cells) and the inflammasome, reflected by inflammasome markers such as nucleotide-binding and oligomerization domain-like receptors protein 3 (NLRP3) and cleaved caspase1 (cCASP-1), were significantly decreased by PS treatment. These results suggest that PS merits further exploration as a therapeutic agent in the management of chronic kidney disease (CKD).

Fluorofenidone Attenuates Renal Interstitial Fibrosis by Enhancing Autophagy and Retaining Mitochondrial Function.

BACKGROUND: Fluorofenidone (AKF-PD) is a novel pyridone agent and has potent anti-NLRP3 inflammasome and anti-fibrotic activities. However, the mechanisms underlying its pharmacological actions are not fully understood. METHODS: A renal fibrosis rat model was established by the unilateral ureteral obstruction (UUO) procedure and the rats were randomized and treated with, or without, AKF-PD for 3 and 7 days. The levels of renal fibrosis, NLRP3 inflammasome activation, mitochondrial function, and autophagy were tested in rat kidney tissues. Macrophages following lipopolysaccharides (LPS) and adenosine 5'-triphosphate (ATP) stimulation were examined by Western blot, spectrophotometry, and TEM. RESULTS: Compared with the untreated UUO rats, AKF-PD treatment significantly mitigated the UUO procedure-induced renal fibrosis in rats. AKF-PD treatment decreased mitochondrial dysfunction and IL-Iß and caspase-1 expression in rat kidney tissues and reduced mitochondrial reactive oxygen species production in activated macrophages. Mechanistically, AKF-PD treatment significantly attenuated the PI3K/AKT/mTOR signaling, increased Beclin-1 and LC3 II expression and autophagosome formation, and ameliorated the mitochondrial damage in renal tissues and activated macrophages. CONCLUSION: The results indicated that AKF-PD treatment inhibited renal interstitial fibrosis by regulating the autophagy-mitochondria-NLRP3 inflammasome pathway.

Atorvastatin reduces renal interstitial fibrosis caused by unilateral ureteral obstruction through inhibiting the transcriptional activity of YAP.

Renal interstitial fibrosis is the primary pathological basis for the progression and development of various chronic kidney diseases, ultimately leading to renal failure. Obstructive kidney disease caused by conditions such as kidney stones, is a common cause of renal fibrosis. The Hippo pathway is a crucial signaling pathway that senses mechanical forces and is involved in the pathophysiology of fibrosis. In this study, we established a mouse model of obstructive kidney disease induced by unilateral ureteral obstruction (UUO). The UUO procedure significantly upregulated YAP and fibrosis-related gene expression in a time-dependent manner. Morphologically, the renal fibrotic lesions associated with hydronephrosis progressively worsened over time in the UUO group. Atorvastatin, which is widely used to lower blood cholesterol levels, has recently been shown to inhibit Yes1 associated protein (YAP). We treated UUO mice with atorvastatin for 3 and 10 days and observed a decrease in the expression of YAP and fibrosis-related genes at the mRNA and protein levels, along with a reduction in the renal fibrosis analyzed by Masson's staining. These findings suggest that atorvastatin may serve as a preventive agent for fibrosis associated with obstructive kidney disease.

Decreased renal expression of PAQR5 is associated with the absence of a nephroprotective effect of progesterone in a rat UUO model.

Fibrosis is a severe complication of chronic kidney disease (CKD). Progesterone, like other sex hormones, plays an important role in renal physiology, but its role in CKD is poorly understood. We investigated progesterone effect on renal fibrosis progression in the rat model of unilateral ureteral obstruction (UUO). Female rats were exposed to UUO, ovariectomy and progesterone administration after UUO with ovariectomy. Expression of key fibrosis markers, proinflammatory cytokines, levels of membrane-bound (PAQR5) and nuclear (PGR) progesterone receptors, and matrix metalloproteinase (MMP) activity were analyzed in the obstructed and intact rat kidney. In all groups exposed to UUO, decreased PAQR5 expression was observed in the obstructed kidney while in the contralateral kidney, it remained unaffected. We found increased mRNA levels for profibrotic COL1A1, FN1, MMP2, TIMP1, TIMP2, proinflammatory IL1α, IL1ß, and IL18, as well as elevated α-SMA and MMP9 proteins, collagen deposition, and MMP2 activity in all UUO kidneys. Progesterone had slight or no effect on the change in these markers. Thus, we demonstrate for the first time diminished sensitivity of the kidney to progesterone associated with renal fibrosis due to a severe decrease in PAQR5 expression that was accompanied by the lack of nephroprotection in a rat UUO model.

Salvianolic Acid C Inhibits the Epithelial-Mesenchymal Transition and Ameliorates Renal Tubulointerstitial Fibrosis.

BACKGROUND: Salvianolic acid C (SAC) is a natural compound derived from Salvia miltiorrhiza that can protect against renal diseases. The aims of this work were to explore the effect of SAC on kidney tubulointerstitial fibrosis and study the associated mechanism. METHODS: Models for unilateral ureteral obstruction (UUO) and aristolochic acid I (AAI) were established in mice to study renal tubulointerstitial fibrosis. Rat kidney fibroblasts (NRK-49F) and human kidney epithelial cells (HK2) were used as cellular models to evaluate the effects of SAC on kidney fibrosis. RESULTS: Treatment with SAC for two weeks reduced the level of renal tubulointerstitial fibrosis in UUO- and AAI-induced fibrotic kidneys, as demonstrated by Masson's staining and Western blot. SAC inhibited extracellular matrix protein expression in NRK-49F cells and TGF-ß-stimulated HK2 cells in dose-dependent fashion. Moreover, SAC inhibited the expression of epithelial-mesenchymal transition (EMT) factors in animal and cellular models of kidney fibrosis, as well as the EMT-related transcription factor snail. Furthermore, SAC inhibited the fibrosis-related signaling pathway Smad3 in the fibrotic kidneys of two mouse models and in renal cells. CONCLUSIONS: We conclude that SAC inhibits EMT and ameliorates tubulointerstitial fibrosis through involvement of the signaling pathway for transforming growth factor-ß (TGF-ß)/Smad.