Irisin ameliorates UUO-induced renal interstitial fibrosis through TGF-ß1/periostin/MMP-2 signaling pathway.

Renal fibrosis is the most common pathway in progressive kidney diseases. The unilateral ureteral obstruction (UUO) model is used to induce progressive renal fibrosis. We evaluated the effects of irisin on renal interstitial fibrosis in UUO mice. The GSE121190, GSE36496, GSE42303, and GSE96101 datasets were downloaded from the Gene Expression Omnibus (GEO) database. In total, 656 differentially expressed genes (DEGs) were identified in normal and UUO mouse renal samples. Periostin and matrix metalloproteinase-2 (MMP-2) were selected to evaluate the effect of irisin on renal fibrosis in UUO mice. In UUO mice, irisin ameliorated renal function, decreased the expression of periostin and MMP-2, and attenuated epithelial-mesenchymal transition and extracellular matrix deposition in renal tissues. In HK-2 cells, irisin treatment markedly attenuated TGF-ß1-induced expression of periostin and MMP-2. Irisin treatment also inhibited TGF-ß1-induced epithelial-mesenchymal transition, extracellular matrix formation, and inflammatory responses. These protective effects of irisin were abolished by the overexpression of periostin and MMP-2. In summary, irisin treatment can improve UUO-induced renal interstitial fibrosis through the TGF-ß1/periostin/MMP-2 signaling pathway, suggesting that irisin may be used for the treatment of renal interstitial fibrosis.

Shenqi Pill Mitigates Renal Interstitial Fibrosis Through Weakening Notch1/Jag1 Pathway.

INTRODUCTION: Shenqi pill (SQP) can be used to treat various kidney related diseases, but its exact mechanism of action remains unclear. We intended to analyze the role and mechanism of SQP on renal interstitial fibrosis (RIF). METHODS: After performing unilateral ureteral obstruction (UUO) surgery following the Institutional Animal Care and Use Committee guidelines, all rats were assigned into the sham group, UUO group, UUO + SQP 1.5 g/kg, UUO + SQP 3 g/kg, and UUO + SQP 6 g/kg groups. After treatment with SQP for 4 weeks, the appearance of kidney, serum creatinine (SCr), and blood urea nitrogen (BUN) levels were monitored in each group. The pathological injury, extracellular matrix (ECM), and Notch1 pathway-related protein levels were measured using H&E staining, Masson staining, immunohistochemistry, and Western blot, respectively. RESULTS: SQP could obviously ameliorate the appearance of the kidney as well as the levels of SCr and BUN in UUO rats (SCr: 67.6 ± 4.64 µM, 59.66 ± 4.96 µM, 48.76 ± 4.44 µM, 40.43 ± 3.02 µM for UUO, low, medium, and high SQP treatment groups; BUN: 9.09 ± 0.97 mM, 7.72 ± 0.61 mM, 5.42 ± 0.42 mM, 4.24 ± 0.34 mM for UUO, low, medium, and high SQP treatment groups; P < .05). SQP also effectively mitigated renal tissue injury in UUO rats (P < .05). Moreover, we uncovered that SQP significantly inhibited Collagen I, α-SMA, Collagen IV, TGF-B1, Notch1, and Jag1 protein expressions in UUO rats kidney (P < .05). CONCLUSION: Our data elucidated that SQP can alleviate RIF, and the mechanism may be related to the Notch1/Jag1 pathway. DOI: 10.52547/ijkd.7703.

Eplerenone reduces lymphangiogenesis in the contralateral kidneys of UUO rats.

Inflammation and fibrosis often occur in the kidney after acute injury, resulting in chronic kidney disease and consequent renal failure. Recent studies have indicated that lymphangiogenesis can drive renal inflammation and fibrosis in injured kidneys. However, whether and how this pathogenesis affects the contralateral kidney remain largely unknown. In our study, we uncovered a mechanism by which the contralateral kidney responded to injury. We found that the activation of mineralocorticoid receptors and the increase in vascular endothelial growth factor C in the contralateral kidney after unilateral ureteral obstruction could promote lymphangiogenesis. Furthermore, mineralocorticoid receptor activation in lymphatic endothelial cells resulted in the secretion of myofibroblast markers, thereby contributing to renal fibrosis. We observed that this process could be attenuated by administering the mineralocorticoid receptor blocker eplerenone, which, prevented the development of fibrotic injury in the contralateral kidneys of rats with unilateral ureteral obstruction. These findings offer valuable insights into the intricate mechanisms underlying kidney injury and may have implications for the development of therapeutic strategies to mitigate renal fibrosis in the context of kidney disease.

Renoprotective effect of rosmarinic acid by inhibition of indoxyl sulfate-induced renal interstitial fibrosis via the NLRP3 inflammasome signaling.

We previously reported that rosmarinic acid (RA) ameliorated renal fibrosis in a unilateral ureteral obstruction (UUO) murine model of chronic kidney disease. This study aimed to determine whether RA attenuates indoxyl sulfate (IS)-induced renal fibrosis by regulating the activation of the NLRP3 inflammasome/IL-1ß/Smad circuit. We discovered the NLRP3 inflammasome was activated in the IS treatment group and downregulated in the RA-treated group in a dose-dependent manner. Additionally, the downstream effectors of the NLRP3 inflammasome, cleaved-caspase-1 and cleaved-IL-1ß showed similar trends in different groups. Moreover, RA administration significantly decreased the ROS levels of reactive oxygen species in IS-treated cells. Our data showed that RA treatment significantly inhibited Smad-2/3 phosphorylation. Notably, the effects of RA on NLRP3 inflammasome/IL-1ß/Smad and fibrosis signaling were reversed by the siRNA-mediated knockdown of NLRP3 or caspase-1 in NRK-52E cells. In vivo, we demonstrated that expression levels of NLRP3, c-caspase-1, c-IL-1ß, collagen I, fibronectin and α-SMA, and TGF- ß 1 were downregulated after treatment of UUO mice with RA or RA + MCC950. Our findings suggested RA and MCC950 synergistically inhibited UUO-induced NLRP3 signaling activation, revealing their renoprotective properties and the potential for combinatory treatment of renal fibrosis and chronic kidney inflammation.

Huoxue Jiedu Huayu recipe inhibits macrophage-secreted vascular endothelial growth factor-a on angiogenesis and alleviates renal fibrosis in the contralateral kidneys of unilateral ureteral obstruction rats.

OBJECTIVE：To elucidate the mechanism by which Huoxue Jiedu Huayu recipe (, HJHR) regulates angiogenesis in the contralateral kidney of unilateral ureteral obstruction (UUO) rats and the mechanism by which it reduces of renal fibrosis. METHODS: Male Wistar rats were randomly divided into 4 groups: the sham group, UUO group (180 d of left ureter ligation), UUO plus eplerenone (EPL) group, and UUO plus HJHR group. After 180 d of oral drug administration, blood and contralateral kidneys were collected for analysis. Angiogenesis- and fibrosis-related indexes were detected. RESULTS: HJHR and EPL improved structural damage and renal interstitial fibrosis in the contralateral kidney and reduced the protein expression levels of α-smooth muscle actin (α-SMA), vimentin and collagen I. Moreover, these treatments could reduce the expression of vascular endothelial growth factor-A (VEGFA) by inhibiting the infiltration of macrophages. Furthermore, HJHR and EPL significantly reduced the expression of CD34 and CD105 by downregulating VEGFA production, which inhibited angiogenesis. Finally, the coexpressions of CD34, CD105 and α-SMA were decreased in the HJHR and EPL groups, indicating that endothelial-to-mesenchymal transition was inhibited. CONCLUSIONS: These findings confirm that HJHR alleviates contralateral renal fibrosis by inhibiting VEGFA-induced angiogenesis, encourage the use of HJHR against renal interstitial fibrosis and provide a theoretical basis for the clinical management of patients with CKD.

Losartan ameliorates renal fibrosis by inhibiting tumor necrosis factor signal pathway.

Losartan is widely used in the treatment of chronic kidney disease (CKD) and has achieved good clinical efficacy, but its exact mechanism is not clear. We performed high-throughput sequencing (HTS) technology to screen the potential target of losartan in treating CKD. According to the HTS results, we found that the tumor necrosis factor (TNF) signal pathway was enriched. Therefore, we conducted in vivo and in vitro experiments to verify it. We found that TNF signal pathway was activated in both unilateral ureteral obstruction (UUO) rats and human proximal renal tubular epithelial cells (HK-2) treated with transforming growth factor-ß1 (TGF-ß1), while losartan can significantly inhibit TNF signal pathway as well as the expression of fibrosis related genes (such as COL-1, α-SMA and Vimentin). These data suggest that losartan may ameliorate renal fibrosis through modulating the TNF pathway.

Emodin improves renal fibrosis in chronic kidney disease by regulating mitochondrial homeostasis through the mediation of peroxisome proliferator-activated receptor-gamma coactivator-1 alpha (PGC-1α).

Chronic kidney disease (CKD) is a leading public health issue associated with high morbidity worldwide. However, there are only a few effective therapeutic strategies for CKD. Emodin, an anthraquinone compound from rhubarb, can inhibit fibrosis in tissues and cells. Our study aims to investigate the antifibrotic effect of emodin and the underlying molecular mechanism. A unilateral ureteral obstruction (UUO)-induced rat model was established to evaluate the effect of emodin on renal fibrosis development. Hematoxylin and eosin staining, Masson's trichrome staining, and immunohistochemistry staining were performed to analyze histopathological changes and fibrotic features after emodin treatment. Subsequently, a transforming growth factor-beta 1 (TGF-ß1)-induced cell model was used to assess the inhibition of emodin on cell fibrosis in vitro. Furthermore, Western blot analysis and real-time quantitative reverse transcription-polymerase chain reaction were performed to validate the regulatory mechanism of emodin on renal fibrosis progression. As a result, emodin significantly improved histopathological abnormalities in rats with UUO. The expression of fibrosis biomarkers and mitochondrial biogenesis-related proteins also decreased after emodin treatment. Moreover, emodin blocked TGF-ß1-induced fibrotic phenotype, lipid accumulation, and mitochondrial homeostasis in NRK-52E cells. Conversely, peroxisome proliferator-activated receptor-gamma coactivator-1 alpha (PGC-1α) silencing significantly reversed these features in emodin-treated cells. Collectively, emodin plays an important role in regulating PGC-1α-mediated mitochondria function and energy homeostasis. This indicates that emodin exhibits great inhibition against renal fibrosis and acts as a promising inhibitor of CKD.

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.

Integrative informatics analysis identifies that ginsenoside Re improves renal fibrosis through regulation of autophagy.

We previously demonstrated that ginsenoside Re (G-Re) has protective effects on acute kidney injury. However, the underlying mechanism is still unclear. In this study, we conducted a meta-analysis and pathway enrichment analysis of all published transcriptome data to identify differentially expressed genes (DEGs) and pathways of G-Re treatment. We then performed in vitro studies to measure the identified autophagy and fibrosis markers in HK2 cells. In vivo studies were conducted using ureteric obstruction (UUO) and aristolochic acid nephropathy (AAN) models to evaluate the effects of G-Re on autophagy and kidney fibrosis. Our informatics analysis identified autophagy-related pathways enriched for G-Re treatment. Treatment with G-Re in HK2 cells reduced autophagy and mRNA levels of profibrosis markers with TGF-ß stimulation. In addition, induction of autophagy with PP242 neutralized the anti-fibrotic effects of G-Re. In murine models with UUO and AAN, treatment with G-Re significantly improved renal function and reduced the upregulation of autophagy and profibrotic markers. A combination of informatics analysis and biological experiments confirmed that ginsenoside Re could improve renal fibrosis and kidney function through the regulation of autophagy. These findings provide important insights into the mechanisms of G-Re's protective effects in kidney injuries.

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.

Kaempferitrin attenuates unilateral ureteral obstruction-induced renal inflammation and fibrosis in mice by inhibiting NOX4-mediated tubular ferroptosis.

Tubular ferroptosis significantly contributes to renal inflammation and fibrosis, critical factors in chronic kidney disease (CKD). This study aims to investigate Kaempferitrin, a potent flavonoid glycoside from Bauhinia forficata leaves, renowned for its anti-inflammatory and antitumor effects, and to elucidate its potential mechanisms in mitigating inflammation and fibrosis induced by tubular ferroptosis. The study investigated Kaempferitrin's impact on tubular ferroptosis using a unilateral ureteral obstruction (UUO) model-induced renal inflammation and fibrosis. In vitro, erastin-induced ferroptosis in primary tubular epithelial cells (TECs) was utilized to further explore Kaempferitrin's effects. Additionally, NADPH oxidase 4 (NOX4) transfection in TECs and cellular thermal shift assay (CETSA) were conducted to identify Kaempferitrin's target protein. Kaempferitrin effectively improved renal function, indicated by reduced serum creatinine and blood urea nitrogen levels. In the UUO model, it significantly reduced tubular necrosis, inflammation, and fibrosis. Its renoprotective effects were linked to ferroptosis inhibition, evidenced by decreased iron, 4-hydroxynonenal (4-HNE), and malondialdehyde (MDA) levels, and increased glutathione (GSH). Kaempferitrin also normalized glutathione peroxidase 4 (GPX4) and Solute Carrier Family 7 Member 11(SLC7A11) expression, critical ferroptosis mediators. In vitro, it protected TECs from ferroptosis and consistently suppressed NOX4 expression. NOX4 transfection negated Kaempferitrin's antiferroptosis effects, while CETSA confirmed Kaempferitrin-NOX4 interaction. Kaempferitrin shows promise as a nephroprotective agent by inhibiting NOX4-mediated ferroptosis in tubular cells, offering potential therapeutic value for CKD.

Delayed treatment with erythropoietin attenuates renal fibrosis in mouse model of unilateral ureteral obstruction.

OBJECTIVES: Erythropoietin (EPO) exerts tissue-protective effects on various organs including the kidney. However, the effects of EPO on established renal fibrosis remain unclear. In this study, we aimed to examine the therapeutic potential of EPO against established renal fibrosis. METHODS: Renal fibrosis was induced in mice by unilateral ureteral obstruction (UUO) and the mice were treated with recombinant human EPO (rhEPO) daily during 7 and 13 days after UUO. The degrees of renal fibrosis, myofibroblast accumulation, and macrophage infiltration; the mRNA expression levels of transforming growth factor (TGF)-ß1 and α1(I) collagen; and the protein levels of Kelch-like ECH-associated protein 1 (Keap1) and nuclear NF-E2-related factor 2 (Nrf2) in the kidneys were assessed on day 14 after UUO. RESULTS: Treatment with rhEPO significantly decreased fibrosis, myofibroblast accumulation, and α1(I) collagen mRNA expression, but it did not significantly affect TGF-ß1 mRNA expression. Although treatment with rhEPO did not significantly affect the total number of interstitial macrophages, it significantly decreased the number of CD86-positive cells (M1 macrophages), while significantly increased the number of CD206-positive cells (M2 macrophages) in the interstitium. Treatment with rhEPO did not affect the Keap1/Nrf2 protein level or the peripheral blood hematocrit value. CONCLUSIONS: These results indicate for the first time that EPO exerts antifibrotic effects against the evolution of established renal fibrosis, possibly by influencing the polarization of infiltrating macrophages.

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.

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.

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.

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.

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.