The Smad3-dependent microRNA let-7i-5p promoted renal fibrosis in mice with unilateral ureteral obstruction

Root of Prunus persica (taoshugen) ameliorated renal fibrosis by inhibiting TGF-β signaling via upregulating Pmepa1 in mice with unilateral ureter obstruction

ETHNOPHARMACOLOGICAL RELEVANCE

Various parts of Prunus persica (L.) Batsch (peach) exhibit medicinal properties and are utilized in traditional Chinese medicine (TCM) for therapeutic purposes. Notably, the root of P. persica, referred to as "taoshugen" in Chinese, is utilized by experienced TCM practitioners for the treatment of liver cirrhosis, suggesting its potential efficacy in mitigating organ fibrosis.

AIM OF THE STUDY

The study aimed to investigate the potential protective role of the water extract of taoshugen (WE-TSG) against chronic kidney disease-associated renal fibrosis and the underlying mechanisms.

MATERIALS AND METHODS

The chemical composition of WE-TSG was characterized using liquid chromatography-tandem mass spectrometry (LC-MS/MS). The anti-renal fibrosis efficacy of WE-TSG was evaluated in vitro using TGF-β1-stimulated renal tubular TCMK1 cells and in vivo using a murine model of unilateral ureter obstruction (UUO). The underlying mechanisms were elucidated using RNA-seq and CRISPR/Cas9-mediated loss of function of candidate genes. The activity of TGF-β signaling and the extent of fibrosis were determined by luciferase reporter assays, histology, immunohistochemistry, RT-PCR, and Western blot.

RESULTS

LC-MS/MS analysis identified 14 major compounds in WE-TSG, primarily flavonoids and organooxygen compounds. In TCMK1 cells, WE-TSG significantly inhibited the activity of TGF-β-responsive luciferase reporters, CAGA-luc and CTGF-luc, and dose-dependently (3.125, 6.25, and 12.5 μg/mL) suppressed TGF-β1-induced Smad2/3 phosphorylation (p-Smad2/3) and fibrotic gene (fibronectin, Col1a1, and Ctgf) expression, without affecting total Smad2/3 protein levels. In vivo, oral administration of WE-TSG (1.4 and 2.8 g/kg) attenuated structural abnormalities, collagen deposition, and fibrotic gene (fibronectin, Col1a1, and α-SMA) expression, alongside reduced TGF-β signaling activity (TGF-β1 and p-Smad2/3) in the kidney tissues of UUO mice. RNA-seq in TCMK1 cells identified that Pmepa1, a negative-feedback regulator of TGF-β signaling, was significantly upregulated upon WE-TSG pretreatment. Importantly, knockout of Pmepa1 abolished the anti-TGF-β signaling and anti-fibrosis effects of WE-TSG in TGF-β1-stimulated TCMK1 cells. Moreover, kidney-targeted Pmepa1 knockdown also abrogated the anti-renal fibrosis role of WE-TSG in UUO mice.

CONCLUSIONS

Our findings demonstrate that WE-TSG inhibits TGF-β signaling and attenuates UUO-induced renal fibrosis by promoting Pmepa1 expression, highlighting the potential of herbal medicine taoshugen in the clinical treatment of CKD.

Biochanin A suppresses Klf6-mediated Smad3 transcription to attenuate renal fibrosis in UUO mice

BACKGROUND

Renal fibrosis is a hallmark of chronic kidney disease (CKD). Smad3 serves as the principal transcription factor mediating the pro-fibrosis effects of TGF-β signaling in renal fibrosis. Biochanin A (BCA), a natural isoflavone, has been shown to attenuate renal fibrosis by inhibiting TGF-β signaling but the detailed mechanisms remain unresolved. This study aimed to elucidate the specific mechanisms by which BCA modulates TGF-β signaling.

METHODS

Renal fibrosis models were established both in vitro, using TGF-β1-stimulated mouse renal tubular TCMK1 cells, and in vivo, employing mice with unilateral ureter obstruction (UUO). RNA-seq was conducted to identify BCA-regulated genes. The AnimalTFDB4.0 database was utilized to predict transcription factors with potential binding to Smad3 promoter. The activities of TGF-β signaling and the cloned mouse Smad3 promoter were assessed using luciferase reporter assays. Plasmid transfection was performed using polyethylenimine in TCMK1 cells or ultrasound microbubbles in UUO kidneys. Gene expression was analyzed by RT-PCR, western blot, and immunohistochemistry assays.

RESULTS

BCA significantly inhibited TGF-β signaling activity and suppressed TGF-β1-induced fibrotic gene expression in TCMK1 cells. RNA-seq and in silico analyses identified Smad3 as the key gene downregulated by BCA, while leaving Smad2 unaffected. This selective transcriptional suppression of Smad3 by BCA was validated by luciferase reporter assays using the cloned Smad3 promoter. Furthermore, transcription factor binding prediction identified that Klf6, a transcription factor downregulated by BCA, has binding potential to the Smad3 promoter and promotes Smad3 transcription. Klf6 expression was induced in TGF-β1-stimulated TCMK1 cells and UUO kidneys, but this induction was abolished upon BCA treatment. Importantly, Klf6 overexpression restored Smad3 expression and counteracted the anti-fibrosis effects of BCA in both TGF-β1-stimulated TCMK1 cells and UUO kidneys.

CONCLUSION

TGF-β-responsive Klf6 transcriptionally transactivates Smad3 expression. BCA exerts anti-renal fibrosis effects by inhibiting the Klf6-Smad3 signaling axis, underscoring its therapeutic potential in the treatment of CKD.

RfxCas13d-mediated inhibition of Circ1647 alleviates renal fibrosis via PI3K/AKT signaling pathway

BACKGROUND

Circular RNAs (CircRNAs) have been shown to be involved in the development of chronic kidney disease (CKD). This study aimed to investigate the role of Circ1647 in renal fibrosis, which is a hallmark of CKD.

METHODS

In this study, we established a unilateral ureteral obstruction (UUO) model and delivered Circ1647 RfxCas13d knockdown plasmid into renal parenchymal cells via retrograde injection through the ureter followed by electroporation. After that, the pathological changes were determined by Hematoxylin and Eosin. Meanwhile, Immunohistochemistry, qRT-PCR and Western blot were conducted to assess the degree of fibrosis. In addition, overexpressing of Circ1647 in renal tubular epithelial cells (TCMK1) was performed to investigate the underlying mechanisms of Circ1647.

RESULTS

Our results displayed that electroporation-mediated knockdown of Circ1647 by RfxCas13d knockdown plasmid significantly inhibited renal fibrosis in UUO mice as evidenced by reduced expression of fibronectin and α-SMA (alpha-smooth muscle actin). Conversely, overexpression of Circ1647 in TCMK1 cells promoted the fibrosis. In terms of mechanism, Circ1647 may mediate the PI3K/AKT Signaling Pathway as demonstrated by the balance of the phosphorylation of PI3K and AKT in vivo and the aggravated phosphorylation of PI3K and AKT in vitro. These observations were corroborated by the effects of the PI3K inhibitor LY294002, which mitigated fibrosis post Circ1647 overexpression.

CONCLUSION

Our study suggests that Circ1647 plays a significant role in renal fibrosis by mediating the PI3K/AKT signaling pathway. RfxCas13d-mediated inhibition of Circ1647 may serve as a therapeutic target for renal fibrosis in CKD.

LncRNA H19 accelerates renal fibrosis by negatively regulating the let-7b-5p/TGF-βR1/COL1A1 axis

BACKGROUND

Transforming growth factor-beta1 (TGF-β1)-mediated renal fibrosis is a critical pathological process of chronic kidney disease worsening to end-stage renal disease. Recent studies have shown that long noncoding RNA H19 (lncRNA H19) is widely involved in the formation and progression of fibrosis in multiple organs. However, its molecular events in renal fibrosis remain to be elucidated.

METHODS

Rats were treated with adenine intragastrically and HK-2 cells were induced by TGF-β1 to construct renal fibrosis models in vivo and in vitro, respectively. Renal histopathological examination was performed using HE and Masson staining. Gene expression levels of interleukin-1beta (IL-1β), tumor necrosis factor-alpha (TNF-α), TGF-β1, fibronectin (Fn), alpha-smooth muscle actin (α-SMA), H19, let-7b-5p, TGF-β receptor 1 (TGF-βR1), and type I collagen (COL1A1) were detected by qRT-PCR. Immunohistochemistry, immunofluorescence, and western blot analysis were used to evaluate the expression of renal fibrosis biomarkers. Dual-luciferase reporter assay was used to verify the presence of binding sites between H19 and let-7b-5p, and between let-7b-5p and TGF-βR1 and COL1A1.

RESULTS

H19 was overexpressed in both in vivo and in vitro renal fibrosis models. H19 knockdown significantly reversed TGF-β1-induced upregulation of fibronectin, COL1A1, and α-SMA and downregulation of E-cadherin in HK-2 cells, accompanied by an increase in let-7b-5p. Let-7b-5p was bound to H19 in HK-2 cells, and its overexpression inhibited TGF-β1-induced HK-2 cell fibrosis. Further experiments determined that let-7b-5p directly targets TGF-βR1 and COL1A1 in HK-2 cells. In addition, inhibition of let-7b-5p reversed the reduction in HK-2 cell fibrosis induced by H19 knockdown. Finally, knockdown of H19 alleviated renal fibrosis in vivo and was associated with regulation of the let-7b-5p/TGF-βR1/COL1A1 axis.

CONCLUSION

Our results indicate that knockdown of H19 inhibits renal tubular epithelial fibrosis by negatively regulating the let-7b-5p/TGF-βR1/COL1A1 axis, which may provide new mechanistic insights into CRF progression.

Mechanism of Chaihuang-Yishen formula to attenuate renal fibrosis in the treatment of chronic kidney disease: Insights from network pharmacology and experimental validation

Renal fibrosis represents a pivotal characteristic of chronic kidney disease (CKD), for which effective interventions are currently lacking. The Src kinase activates the phosphatidylinositol-3 kinases (PI3K)/Akt1 pathway to promote renal fibrosis, casting a promising target for anti-fibrosis treatment. Chaihuang-Yishen formula (CHYS), a traditional Chinese medicinal prescription, has a validated efficacy in the treatment of CKD, however, with the underlying mechanism unresolved. This study aimed to uncover the pharmacological mechanisms mediating the effect of CHYS in treating renal fibrosis using network pharmacology followed by experimental validation. The chemical compounds of CHYS were retrieved from the Traditional Chinese Medicine Systems Pharmacology (TCMSP) database or published literature, followed by the prediction of their targets using SwissTargetPrediction software. Disease (CKD/renal fibrosis)-related targets were retrieved from the Genecards database. Protein-protein interaction (PPI) network was generated using the drug-disease common targets and visualized in Cytoscape software. The drug-disease targets were further subjected to Gene Ontology (GO) and Kyoto Encyclopedia of Genes and Genomes (KEGG) enrichment analyses by Metascape software. Additionally, the compound-target-pathway network was established in Cytosape to identify key compounds, targets, and pathways. Network pharmacology analysis screened out 96 active compounds and 837 potential targets within the 7 herbal/animal medicines of CHYS, among which 237 drug-disease common targets were identified. GO and KEGG analysis revealed the enrichment of fibrosis-related biological processes and pathways among the 237 common targets. Compound-target-pathway network analysis highlighted protein kinases Src and Akt1 as the top two targets associated with the anti-renal fibrosis effects of CHYS. In UUO mice, treatment with CHYS attenuates renal fibrosis, accompanied by suppressed expression and phosphorylation activation of Src. Unlike Src, CHYS reduced Akt1 phosphorylation without affecting its expression. In summary, network pharmacology and in vivo evidence suggest that CHYS exerts its anti-renal fibrosis effects, at least in part, by inhibiting the Src/Akt1 signaling axis.

Optimized rAAV8 targeting acinar KLF4 ameliorates fibrosis in chronic pancreatitis via exosomes-enriched let-7s suppressing pancreatic stellate cells activation

Chronic pancreatitis (CP) is marked by progressive fibrosis and the activation of pancreatic stellate cells (PSCs), accompanied by the destruction of pancreatic parenchyma, leading to the loss of acinar cells (ACs). Few research studies have explored the mechanism by which damaged ACs (DACs) contribute to PSCs activation and pancreatic fibrosis. Currently, there are no effective drugs for curing CP or limiting the progression of pancreatic fibrosis. In this research, co-culture with intact acinar cells (IACs) suppressed PSC activation, while co-culture with DACs did the opposite. Krüppel-like factor 4 (KLF4) was significantly upregulated in DACs and was established as the key molecule that switches ACs from PSCs-suppressor to PSCs-activator. We revealed the exosomes of IACs contributed to the anti-activated function of IACs-CS on PSCs. MiRNome profiling showed that let-7 family is significantly enriched in IAC-derived exosomes (>30% miRNome), which partially mediates IACs' suppressive impacts on PSCs. Furthermore, it has been observed that the enrichment of let-7 in exosomes was influenced by the expression level of KLF4. Mechanistic studies demonstrated that KLF4 in ACs upregulated Lin28A, thereby decreasing let-7 levels in AC-derived exosomes, and thus promoting PSCs activation. We utilized an adeno-associated virus specifically targeting KLF4 in ACs (shKLF4-pAAV) to suppress PSCs activation in CP, resulting in reduced pancreatic fibrosis. IAC-derived exosomes hold potential as potent weapons against PSCs activation via let-7s, while activated KLF4/Lin28A signaling in DACs diminished such functions. ShKLF4-pAAV holds promise as a novel therapeutic approach for CP.

Plasma and Myocardial miRNomes Similarities and Differences during Cardiac Remodelling and Reverse Remodelling in a Murine Model of Heart Failure with Preserved Ejection Fraction

Heart failure with preserved ejection fraction (HFpEF) is a heterogeneous syndrome characterised by multiple risk factors touching various organs outside the heart. Using a murine HFpEF model, we studied cardiac reverse remodelling (RR) after stopping the causing metabolic-hypertensive stress (MHS; Angiotensin II [AngII] and a high-fat diet [HFD]) after 28 days and introducing voluntary exercise (VE) for four more weeks. We measured the effects of MHS and RR on the plasma and myocardial microRNA (miR) profile (miRNome) to characterise better cardiac and non-cardiac responses to HFpEF-inducing risk factors and their reversibility. AngII alone, the HFD or the MHS caused cardiac hypertrophy (CH), left ventricular (LV) concentric remodelling and left atrial enlargement in females. Only AngII and the MHS, but not HFD, did in males. After RR, CH, LV concentric remodelling and atrial enlargement were normalised. Among the 25 most abundant circulating miRs, 10 were modulated by MHS. Plasma miRNomes from AngII, HFD or MHS mice shared 31 common significantly modulated miRs (24 upregulated and 7 downregulated), suggesting that the response of organs producing the bulk of those circulating miRs was similar even for seemingly different stress. In the LV, 19 out of 25 most expressed miRs were modulated. RR restored normality for the plasma miRNome but not for the LV miRNome, which remained mostly unchanged. Our results suggest that abnormalities persist in the myocardium of the HFpEF mice and that the normalisation of circulatory markers may be falsely reassuring after recovery.

Therapeutic potential for renal fibrosis by targeting Smad3-dependent noncoding RNAs

Renal fibrosis is a characteristic hallmark of chronic kidney disease (CKD) that ultimately results in renal failure, leaving patients with few therapeutic options. TGF-β is a master regulator of renal fibrosis and mediates progressive renal fibrosis via both canonical and noncanonical signaling pathways. In the canonical Smad signaling, Smad3 is a key mediator in tissue fibrosis and mediates renal fibrosis via a number of noncoding RNAs (ncRNAs). In this regard, targeting Smad3-dependent ncRNAs may offer a specific therapy for renal fibrosis. This review highlights the significance and innovation of TGF-β/Smad3-associated ncRNAs as biomarkers and therapeutic targets in renal fibrogenesis. In addition, the underlying mechanisms of these ncRNAs and their future perspectives in the treatment of renal fibrosis are discussed.

Puerarin alleviates chronic renal failure-induced pyroptosis in renal tubular epithelial cells by targeting miR-342-3p/TGF-β/SMAD axis

BACKGROUND

Chronic renal failure (CRF) is the result of kidney damage. Puerarin is a flavonoid with specific nephroprotective effect, but its effect on CRF needs further research. This study explored the effect of puerarin on CRF and the potential molecular mechanism.

METHODS

Adenine was used to establish an in vivo CRF model in rats, and rats were intragastrically administered with puerarin at a dose of 400 mg/kg body weight once a day from day 1 to day 28. Hematoxylin and eosin (HE) and Masson staining were used to observe the morphology and fibrosis of kidney tissue. Lipopolysaccharide (LPS) (400 ng/mL)/H2O2 (200 µM) was applied to human kidney 2 (HK-2) cells to construct an in vitro CRF model. Enzyme-linked immunosorbent assay (ELISA) was performed to validate interleukin (IL)-1β and IL-18 levels. Quantitative reverse transcription polymerase chain reaction (RT-qPCR) was performed to detect microRNA (miR)-342-3p levels. Transforming growth factor beta (TGF-β)1, SMAD2, SMAD3, and pyroptosis marker proteins were detected by Western blot. The interaction between miR-342-3p and TGF-β/SMAD was determined by a dual-luciferase reporter gene assay. Cell Counting Kit-8 (CCK-8) assay was utilized to determine cell viability.

RESULTS

In the CRF model, puerarin alleviated renal injury and fibrosis and reduced creatinine (Cr) and blood urea nitrogen (BUN) levels. At the same time, miR-342-3p was downregulated, while the TGF-β/SMAD axis was activated and levels of IL-1β and IL-18 were increased. After treatment of CRF rats with puerarin, the expression level of miR-342-3p was increased, the TGF-β/SMAD axis was inhibited, and the secretion of IL-1β and IL-18 was decreased. MiR-342-3p directly bound to and negatively regulated the expression of TGF-β1, SMAD2, and SMAD3. In the in vitro CRF model, miR-342-3p inhibited HK-2 cell pyroptosis by inhibiting the TGF-β/SMAD axis.

CONCLUSION

Puerarin reduced renal injury and pyroptosis in CRF rats by targeting the miR-342-3p/TGF-β/SMAD axis.

Btg2 Promotes Focal Segmental Glomerulosclerosis via Smad3-Dependent Podocyte-Mesenchymal Transition

Podocyte injury plays a critical role in the progression of focal segmental glomerulosclerosis (FSGS). Here, it is reported that B-cell translocation gene 2 (Btg2) promotes Adriamycin (ADR)-induced FSGS via Smad3-dependent podocyte-mesenchymal transition. It is found that in FSGS patients and animal models, Btg2 is markedly upregulated by podocytes and correlated with progressive renal injury. Podocyte-specific deletion of Btg2 protected against the onset of proteinuria and glomerulosclerosis in ADR-treated mice along with inhibition of EMT markers such as α-SMA and vimentin while restoring epithelial marker E-cadherin. In cultured MPC5 podocytes, overexpression of Btg2 largely promoted ADR and TGF-β1-induced EMT and fibrosis, which is further enhanced by overexpressing Btg2 but blocked by disrupting Btg2. Mechanistically, Btg2 is rapidly induced by TGF-β1 and then bound Smad3 but not Smad2 to promote Smad3 signaling and podocyte EMT, which is again exacerbated by overexpressing Btg2 but blocked by deleting Btg2 in MPC5 podocytes. Interestingly, blockade of Smad3 signaling with a Smad3 inhibitor SIS3 is also capable of inhibiting Btg2 expression and Btg2-mediated podocyte EMT, revealing a TGF-β/Smad3-Btg2 circuit mechanism in Btg2-mediated podocyte injury in FSGS. In conclusion, Btg2 is pathogenic in FSGS and promotes podocyte injury via a Smad3-dependent EMT pathway.

Research progress on the mechanism of renal interstitial fibrosis in obstructive nephropathy

Renal fibrosis is a common result for various chronic kidney diseases developing to the end stage. It is a pathological process characterized by the destruction of normal kidney structure and the subsequent replacement with fibrous tissue, which primarily involves fibroblast proliferation and extracellular matrix deposition. Obstruction is a common cause of renal fibrosis, and obstructive renal fibrosis is a common disease in urology. Obstructive renal fibrosis, characterized by its insidious onset, is the result of a complex interplay of multiple factors. These factors encompass renal tubular epithelial cell injury, the presence of a hypoxic microenvironment in affected kidney tissue, inflammatory cell infiltration, release of inflammatory mediators, and the release of renal fibrosis growth factors, among others. This paper reviews the research progress on the mechanism and treatment of renal interstitial fibrosis.

Synergism of calycosin and bone marrow-derived mesenchymal stem cells to combat podocyte apoptosis to alleviate adriamycin-induced focal segmental glomerulosclerosis

BACKGROUND

Bone marrow-derived mesenchymal stem cells (MSCs) show podocyte-protective effects in chronic kidney disease. Calycosin (CA), a phytoestrogen, is isolated from Astragalus membranaceus with a kidney-tonifying effect. CA preconditioning enhances the protective effect of MSCs against renal fibrosis in mice with unilateral ureteral occlusion. However, the protective effect and underlying mechanism of CA-pretreated MSCs (MSCsCA) on podocytes in adriamycin (ADR)-induced focal segmental glomerulosclerosis (FSGS) mice remain unclear.

AIM

To investigate whether CA enhances the role of MSCs in protecting against podocyte injury induced by ADR and the possible mechanism involved.

METHODS

ADR was used to induce FSGS in mice, and MSCs, CA, or MSCsCA were administered to mice. Their protective effect and possible mechanism of action on podocytes were observed by Western blot, immunohistochemistry, immunofluorescence, and real-time polymerase chain reaction. In vitro, ADR was used to stimulate mouse podocytes (MPC5) to induce injury, and the supernatants from MSC-, CA-, or MSCsCA-treated cells were collected to observe their protective effects on podocytes. Subsequently, the apoptosis of podocytes was detected in vivo and in vitro by Western blot, TUNEL assay, and immunofluorescence. Overexpression of Smad3, which is involved in apoptosis, was then induced to evaluate whether the MSCsCA-mediated podocyte protective effect is associated with Smad3 inhibition in MPC5 cells.

RESULTS

CA-pretreated MSCs enhanced the protective effect of MSCs against podocyte injury and the ability to inhibit podocyte apoptosis in ADR-induced FSGS mice and MPC5 cells. Expression of p-Smad3 was upregulated in mice with ADR-induced FSGS and MPC5 cells, which was reversed by MSCCA treatment more significantly than by MSCs or CA alone. When Smad3 was overexpressed in MPC5 cells, MSCsCA could not fulfill their potential to inhibit podocyte apoptosis.

CONCLUSION

MSCsCA enhance the protection of MSCs against ADR-induced podocyte apoptosis. The underlying mechanism may be related to MSCsCA-targeted inhibition of p-Smad3 in podocytes.