Proteinuria is an independent risk factor for the progression of diabetic nephropathy (DN) and an imbalance in podocyte function aggravates proteinuria. Celastrol is the primary active ingredient of T. wilfordii, effective in treating DN renal injury; however, the mechanisms underlying its effect are unclear. We explored how celastrol prevents DN podocyte damage using in vivo and in vitro experiments. We randomly divided 24 male C57BLKS/J mice into three groups: db/m (n = 8), db/db (n = 8), and celastrol groups (db/db + celastrol, 1 mg/kg/d, gavage administration, n = 8). In vivo experiments lasted 12 weeks and intervention lasted ten weeks. Serum samples and kidney tissues were collected for biochemical tests, pathological staining, transmission electron microscopy, fluorescencequantitation polymerase chain reaction, and western blotting analysis. In vitro experiments to elaborate the mechanism of celastrol protection were performed on high glucose (HG)-induced podocyte injury. Celastrol reduced blood glucose levels and renal function index in db/db mice, attenuated renal histomorphological injury and glomerular podocyte foot injuries, and induced significant anti-inflammatory effects. Celastrol upregulated silent information regulator 2 related enzyme 1(SIRT1) expression and downregulated enhancer of zeste homolog (EZH2), inhibiting the wnt/β-catenin pathway-related molecules, such as wnt1, wnt7a, and β-catenin. SIRT1 repressed the promoter activity of EZH2, and was co-immunoprecipitated with EZH2 in mouse podocyte cells (MPC5). SIRT1 knockdown aggravated the protective effects of celastrol on MPC5 cells. Celastrol protected podocyte injury via SIRT1/EZH2, which participates in the wnt/β-catenin pathway. Overall, celastrol-mediated SIRT1 upregulation inhibited the EZH2-related wnt/β-catenin signaling pathway to attenuate DN and podocyte injury, providing a theoretical basis for celastrol clinical application.

Aim: The aim of this study was to investigate the renoprotective effects of exosomes derived from rat bone marrow mesenchymal stem cells (rBMSCs) in a rat model of 5/6 nephrectomy (Nx)-induced chronic kidney disease (CKD). Methods: A rat model of 5/6 Nx-induced CKD was established using conventional method. rBMSC-derived exosomes were isolated using ultracentrifugation and characterized. The exosomes were injected into 5/6 Nx rats through the caudal vein. After 12 weeks, 24 h proteinuria, serum creatinine (SCr), and blood urea nitrogen (BUN) levels were evaluated, and renal pathology was analyzed by H&E and Masson staining, and transmission electron microscopy. The expression of klotho was analyzed and the activity of the klotho promoter was evaluated using a luciferase reporter assay. Results: The isolated exosomes showed typical morphological features. Exosomes transplantation reduced 24 h urinary protein excretion, and SCr and BUN levels in 5/6 Nx-induced CKD rats. Furthermore, renal pathology was improved in the exosome-treated 5/6 Nx rats. Mechanistically, the exosomes significantly upregulated the activity of klotho promoter and its expression. Conclusions: Transplantation of rBMSC-derived exosomes may protect against kidney injury, probably by regulating klotho activity and expression. Our results provide a theoretical basis for the application of rBMSC-derived exosomes in CKD therapy.

Focal segmental glomerulosclerosis (FSGS) is the most common glomerular etiology of end-stage kidney disease (ESKD). Increasing evidence has indicated the reparative potential of mesenchymal stem cells (MSCs) in damaged diseased kidneys. However, the effect of bone marrow mesenchymal stem cells (BMSCs) on the FSGS progression remains unclear. This study aimed to investigate the protective effects of BMSCs on FSGS progression. A rat model of FSGS was generated via unilateral nephrectomy plus adriamycin injection. Rat BMSCs were isolated and characterized on the basis of their differentiative potential towards adipocytes and osteoblasts and via flow cytometry analysis. Thereafter, rat BMSCs were transplanted into FSGS recipients through the caudal vein. After 8 weeks, 24-h proteinuria, serum creatinine, and urea nitrogen levels were determined. Renal morphology was assessed using a light and transmission electron microscope. MMP9 and TIMP-1 positive cells were detected via immunohistochemical analysis. Expression levels of proinflammatory cytokines IL-6 and TNF-α were examined via RT-PCR. The isolated adherent cells from the bone marrow of rats were phenotypically and functionally equivalent to typical MSCs. Clinical examination revealed that BMSC transplantation reduced the 24-h urinary protein excretion, and serum creatinine and urea nitrogen levels. Renal morphology was ameliorated in BMSCs-transplanted rats. Mechanistically, BMSC transplantation significantly downregulated TIMP-1 and upregulated MMP9, thereby increasing the renal MMP9/TIMP-1 ratio. Moreover, BMSC transplantation also downregulated IL-6 and TNF-α. BMSC transplantation can attenuate FSGS progression in a rat model of FSGS, thereby providing a theoretical foundation for the application of autologous BMSCs in clinical FSGS therapy.

Renal injury is an important factor in the development of chronic kidney diseases that pathologically manifested as renal fibrosis and podocyte damage. In the disease state, renal fibroblasts lead to high expression levels of α-smooth muscle actin (α-SMA), while podocytes undergo epithelial–mesenchymal transition, leading to proteinuria. Celastrol, a bioactive compound in the medicinal plant Tripterygium wilfordii, was found to delay the progression of early diabetic nephropathy and attenuate renal fibrosis in mice with unilateral ureteral obstruction. However, its effect on the renal system in 5/6 nephrectomized (Nx) rats remains unknown. The aim of this study was to explore the protective effects of celastrol and its underlying mechanisms in 5/6 Nx rats. We found that 24 h proteinuria and levels of blood urea nitrogen, serum creatinine, triglycerides, serum P, renal index and cholesterol significantly increased ( P < 0.05), while that of serum albumin decreased significantly in 5/6 Nx rats. After intervention with celastrol, 24 h proteinuria and levels of blood urea nitrogen, serum creatinine, triglycerides, serum P, renal index, and cholesterol significantly decreased, while that of serum albumin significantly increased. Renal tissue pathological staining and transmission electron microscopy showed that celastrol ameliorated kidney injury and glomerular podocyte foot injury and induced significant anti-inflammatory effects. Quantitative polymerase chain reaction (PCR) and western blotting results revealed that nephrin and NEPH1 expression levels were upregulated, whereas α-SMA and Col4a1 expression levels were downregulated in the celastrol group. Celastrol inhibited the expression of transforming growth factor (TGF)-β1/Smad3 signaling pathway-related molecules such as TGF-β1 and P-Smad3. In summary, celastrol contributes to renal protection by inhibiting the epithelial–mesenchymal transdifferentiation and TGF-β1/Smad3 pathways.

Ischemic acute kidney injury (AKI) is a prevalent disorder among hospitalized patients worldwide. Astragaloside IV (AS-IV) has been shown to protect against ischemic AKI. However, the specific effects and mechanisms of AS-IV on alleviating kidney ischemia-reperfusion (I/R) injury remain unclear. The objective of this research was to elucidate the regulatory targets and mechanisms through which AS-IV protects kidney I/R injury. A combination of network pharmacology, molecular docking, molecular dynamics (MD) simulation, pharmacodynamic study and Western blot were employed to explore the underlying mechanisms. Network pharmacology revealed that ferroptosis was a potential mechanism of AS-IV against kidney I/R injury. Molecular docking and MD simulations demonstrated strong binding affinity between the GPX4/SLC7A11 and AS-IV. The experimental verification demonstrated that AS-IV improved cell proliferation, decreased the level of ROS and Fe²⁺, and increased the expressions of GPX4 and SLC7A11 as same as Ferrostatin-1 in OGD/R-injured HUVECs. In conclusion, AS-IV had a significant inhibition on ferroptosis in kidney I/R injury, providing a new perspective for drug development on kidney I/R injury. Definitely, further exploration in vivo is necessary to fully understand whether AS-IV alleviates kidney I/R injury through inhibiting endothelial ferroptosis.