Diabetic Nephropathy Mice Research Articles

Cell Division Cycle 42 Improves Renal Functions, Fibrosis, Th1/Th17 Infiltration and Inflammation to Some Degree in Diabetic Nephropathy.

Our two previous studies observed that cell division cycle 42 (CDC42) was lower and correlated with improved renal function and inflammation in diabetic nephropathy (DN) patients, and CDC42 inhibited renal tubular epithelial cell fibrosis and inflammation under high glucose condition. Sequentially, this current study aimed to investigate the effect of CDC42 on improving renal function, fibrosis, and inflammation in DN mice, and its interaction with T cell receptor (TCR) related pathways. Mice were treated by streptozotocin to construct early-stage DN model, then transfected with CDC42 overexpression adenovirus, followed by simultaneous treatment of LY294002 (PI3K/AKT inhibitor) and CI-1040 (ERK inhibitor), respectively. CDC42 reduced blood glucose, creatinine, and 24h urine protein in DN mice, but only showed a tendency to decrease blood urea nitrogen without statistical significance. Hematoxylin&eosin staining revealed that CDC42 descended the glomerular volume, basement membrane thickness, and inflammatory cell infiltration in kidney. Meanwhile, CDC42 lowered fibronectin, TGF-β1, and Collagen I expressions in kidney, but not decreased α-SMA significantly. Besides, CDC42 decreased T-helper (Th) 1 and Th17 cells in kidney, and reduced serum IFN-γ, IL-1β, IL-17A, and TNF-α but not IL-6. Regarding TCR-related pathways, CDC42 activated AKT and ERK pathways but not JNK pathway. However, the treatment of LY294002 and CI-1040 had limited effect on attenuating CDC42's functions on renal function and fibrotic markers. CDC42 improves renal functions, fibrosis, Th1/Th17 infiltration and inflammation to some degree in DN mice, these functions may be independent to AKT and ERK pathways.

Protective Effect of Mesenchymal Stromal Cells in Diabetic Nephropathy: The In vitro and In vivo Role of the M-Sec-Tunneling Nanotubes.

 Mitochondrial dysfunction plays an important role in the development of podocyte injury in diabetic nephropathy (DN). Tunnelling nanotubes (TNTs) are long channels that connect cells and allow organelle exchange. Mesenchymal stromal cells (MSCs) can transfer mitochondria to other cells through the M-Sec-TNTs system. However, it remains unexplored whether MSCs can form heterotypic TNTs with podocytes, thereby enabling the replacement of diabetes-damaged mitochondria. In this study, we analysed TNT formation, mitochondrial transfer, and markers of cell injury in podocytes that were pre-exposed to diabetes-related insults and then co-cultured with diabetic or non-diabetic MSCs. Furthermore, to assess the in vivo relevance, we treated DN mice with exogenous MSCs, either expressing or lacking M-Sec, carrying fluorescent-tagged mitochondria. MSCs formed heterotypic TNTs with podocytes, allowing mitochondrial transfer, via a M-Sec-dependent mechanism. This ameliorated mitochondrial function, nephrin expression, and reduced apoptosis in recipient podocytes. However, MSCs isolated from diabetic mice failed to confer cytoprotection due to Miro-1 downregulation. In experimental DN, treatment with exogenous MSCs significantly improved DN, but no benefit was observed in mice treated with MSCs lacking M-Sec. Mitochondrial transfer from exogenous MSCs to podocytes occurred in vivo in a M-Sec-dependent manner. These findings demonstrate that the M-Sec-TNT-mediated transfer of mitochondria from healthy MSCs to diabetes-injured podocytes can ameliorate podocyte damage. Moreover, M-Sec expression in exogenous MSCs is essential for providing renoprotection in vivo in experimental DN.

CD3D silencing alleviates diabetic nephropathy via inhibition of JAK/STAT pathway.

Diabetic nephropathy (DN) is a severe microvascular complication of diabetes that poses a significant burden to global health. This investigation aims to illustrate the functional role of CD3D and its relevant mechanisms in DN progression. The pivotal genes between the GSE47183 and GSE30528 datasets were identified using bioinformatics methods. The effects of CD3D silencing on renal damage, inflammatory response, and lipid metabolism were validated in DN mice. Furthermore, the impacts of CD3D knockdown on cell viability, apoptotic rate, inflammation, and lipid levels were investigated in HK-2 cells under high glucose (HG) conditions. Additionally, RO8191 was employed to investigate the role of CD3D in the JAK/STAT pathway in HG-treated cells. A total of 5 focal genes were identified through bioinformatics and were found to be upregulated in renal tissues from DN mice. CD3D silencing mitigated pathological damage to kidneys, reduced inflammatory response, and decreased lipid accumulation in DN mice. HG stimulation restrained viability, increased apoptosis, promoted the release of inflammatory cytokines, and affected expressions of hallmarks related to lipid metabolism in HG-treated cells; these changes were partially abolished by CD3D knockdown. Mechanistically, CD3D downregulation ameliorated HG-induced injury in HK-2 cells by blocking the JAK/STAT pathway. This study underscores that CD3D silencing has significant potential as a promising candidate in the treatment of DN.

Suppression of ferroptosis through the SLC7A11/glutathione/glutathione peroxidase 4 axis contributes to the therapeutic action of the Tangshenning formula on diabetic renal tubular injury

BackgroundTangshenning (TSN) is a safe and effective formula to treat diabetic nephropathy (DN), and clinical studies have demonstrated that its therapeutic effects are related to oxidative stress improvements in patients. Herein, this study aims to explore the potential mechanism of how TSN alleviates diabetic renal tubular injury.MethodsThe ultrahigh pressure liquid chromatography-quadrupole-time of flight mass spectrometry (UPLC-QTOF/MS) was used to identify the chemical composition and serum components of TSN. KK-Ay mice served to investigate the protective effects and regulatory mechanisms of TSN on tubular damage in DN. Furthermore, inhibitors and inducers of ferroptosis were employed in high glucose-cultured tubular epithelial cells (TECs) to verify the potential mechanisms of TSN. The expressions of proteins related to renal tubular injury, ferroptosis and solute carrier family 7, member 11 (SLC7A11)/glutathione (GSH)/glutathione peroxidase 4 (GPX4) axis were analyzed by western blot and immunofluorescence. Mitochondrial ultrastructure was observed in kidney tissues and TECs by a transmission electron microscope. Pathological changes in the renal tissues were observed by HE, PAS, and Prussian blue staining. Ferroptosis-related reactive oxygen species (ROS), malondialdehyde (MDA), ferrous ion, the intake of cystine, GSH, and oxidized glutathione (GSSG) were evaluated and contrasted in vivo or in vitro.Results51 compounds of TSN powder and 11 components in TSN-containing serum were identified by UPLC-QTOF/MS method. Administration of TSN ameliorated the elevated levels of proteinuria, serum creatinine, blood urea nitrogen, abnormal expression of renal tubular injury markers, and pathological damage to the renal tubules in DN mice model. Intriguingly, a strong inhibition of ferroptosis after TSN treatment occurred in both DN mice model and high glucose-cultured TECs. Notably, induction of ferroptosis by erastin attenuated the protective effect of TSN in high glucose-cultured TECs, while the ferroptosis inhibition by ferrostatin-1 treatment protected renal tubular, which was similar to TSN, suggesting the contribution of TSN-mediated by the inhibition of ferroptosis in DN progression. Mechanistically, TSN upregulated the SLC7A11/GSH/GPX4 axis to inhibit ferroptosis.ConclusionTSN may delay the DN progression and attenuate the renal tubular injury by inhibiting the ferroptosis regulated by the SLC7A11/GSH/GPX4 axis.

Strobilanthes sarcorrhiza root phenolic extract prevent diabetic nephropathy in mice by regulating NF-κB/IL-1β signaling and glycerophospholipid metabolism

Strobilanthes sarcorrhiza, a folk medicine from China, is known to treat kidney deficiency and lumbago. However, its protective effects and mechanisms against diabetic nephropathy (DN) remain unclear. This study aimed to investigate the effects and mechanisms of Strobilanthes sarcorrhiza root phenolic extract (CTS) on streptozotocin (STZ)-induced DN in mice. Firstly, the constituents in CTS were characterized by UPLC-QTOF-MS. Thirty-three constituents were identified, including 12 phenylethanoid glycosides and their derivatives, 14 phenylpropanoid glycosides derivatives, 6 polyphenols derivatives, and 1 other constituent. Then, utilizing the identified constituents of CTS, network pharmacology was used to anticipate potential pathways against DN. Thirty-two out of thirty-three constituents showed anti-DN activity; their mechanism of action was significantly linked to tumor-, glycosylation-, metabolism-related pathways, etc. Furthermore, the effectiveness of CTS against DN and its in vivo mechanism was assessed by combining immunohistochemistry, untargeted metabolomics, biochemical evaluation, and histopathological examination. The findings showed that CTS improved blood glucose and lipid levels in diabetic mice, reduced serum levels of ALT, CREA, UREA, IL-1β, and IL-17, decreased pathological damage and fibrosis in kidney tissue, and lowered the protein expression of VEGF, Laminin, TNF-α, and NF-κB in kidney tissue. Metabolomics results indicated that CTS alleviated DN mainly by regulating glycerophospholipid metabolism. To the best of our knowledge, this study is the first to report that Strobilanthes sarcorrhiza attenuates DN, potentially through the inhibition of the NF-κB pathway, leading to a reduction in the inflammatory response and fibrosis of renal tissue. These findings suggest that Strobilanthes sarcorrhiza could be a promising therapeutic agent for DN.

Mechanism of the cardioprotective effect of empagliflozin on diabetic nephropathy mice based on the basis of proteomics

Diabetic nephropathy affects a significant proportion of individuals with diabetes, and its progression often leads to cardiovascular disease and infections before the need for renal replacement therapy arises. Empagliflozin has been shown to have various protective effects in cardiovascular disease studies, such as improving diabetic myocardial structure and function, and reducing myocardial oxidative stress. However, the impact of empagliflozin on cardiac protein expression and signaling pathways has not been comprehensively analyzed. To address this gap, we conducted proteome analysis to identify specific protein markers in cardiac tissue from the diabetes model group, including Myh7, Wdr37, Eif3k, Acot1, Acot2, Cat, and Scp2, in cardiac tissue from the diabetes model group. In our drug model, empagliflozin primarily modulates the fat-related metabolic signaling pathway within the heart. Empagliflozin downregulated the protein expression levels of ACOX1, ACADVL and CPT1A in the model group. Overall, our findings demonstrate that empagliflozin provides cardiac protection by targeting metabolic signaling pathways, particularly those related to fat metabolism. Moreover, the identification of cardiac biomarkers in a mouse model of diabetic nephropathy lays the foundation for further exploration of disease biomarkers in cardiac tissue.

NSUN2 knockdown inhibits macrophage infiltration in diabetic nephropathy via reducing N5-methylcytosine methylation of SOCS1.

N5-methylcytosine (m5C) methylation is involved in various disease progression; however, its role in diabetic nephropathy (DN) has not been studied. The aim of this study was to investigate the role of NSUN2 in DN and the underlying mechanism. Streptozotocin-induced experimental mouse model was generated to analyze the role of NSUN2 in vivo, and high glucose (HG)-treated Raw264.7 cells were used to assess the effect of NSUN2 on macrophage infiltration in vitro. The regulation of NSUN2 on SOCS1 m5C methylation was evaluated using m5C methylated RNA immunoprecipitation, luciferase reporter analysis, and RNA stability determination assay. The results indicated that NSUN2 was highly expressed in the blood and kidney of DN mice. Knockdown of NSUN2 alleviated kidney damage, reduced blood glucose and urine albumin, and suppressed macrophage infiltration in DN mice. Moreover, NSUN2 interacted with SOCS1, and silenced NSUN2 inhibited m5C levels of SOCS1 to reduce SOCS1 mRNA stability. Additionally, interference with NSUN2 suppressed macrophage migration, invasion, and infiltration by positively regulating SOCS1 expression under HG conditions. In conclusion, silencing of NSUN2 inhibits macrophage infiltration by reducing m5C modification of SOCS1, and thereby attenuates renal injury. The findings suggest a novel regulatory mechanism between NSUN2-mediated m5C modification and DN.

Crocin Inhibited Epithelial-Mesenchymal Transition in Renal Tubular Epithelial Cells to Treat Diabetic Nephropathy Through Improving AMPK/mTOR-Mediated Autophagy

Objectives Diabetic nephropathy (DN), a severe microvascular complication of diabetes mellitus, is a leading cause of end-stage renal disease. Crocin (CRO), an active ingredient extracted from Crocus sativus and Gardenia jasminoides, has multiple bioactivities such as anti-oxidative, anti-inflammatory, anti-tumor, and anti-depressive activities. However, the potential effects and mechanisms of CRO in the treatment of DN are still unclear. Methods In this study, we aimed to assess the efficacy of CRO in treating DN using in vivo and in vitro experiments, and intensively investigate the potential therapeutic mechanisms of CRO against DN based on the inhibition of epithelial-mesenchymal transition (EMT) by inducing adenosine monophosphate-activated protein kinase (AMPK)/mammalian target of rapamycin (mTOR)-mediated autophagy. Results The results showed that CRO had a therapeutic effect and anti-EMT effect in kidney of DN mice. CRO also moderated AMPK/mTOR pathway and improved autophagy in kidney of DN mice. In high glucose (HG)-induced tubular epithelial cell EMT model, CRO inhibited EMT, moderated AMPK/mTOR pathway and improved autophagy. AMPK inhibitor abolished the above effects of CRO on tubular epithelial cells. Conclusion CRO exhibited considerably therapeutic and anti-EMT effects on DN both in vivo and in vitro, these may be associated with restoring autophagy through regulating AMPK/mTOR pathway.

Dang-Gui-Bu-Xue decoction against diabetic nephropathy via modulating the carbonyl compounds metabolic profile and AGEs/RAGE pathway

BackgroundDang-Gui-Bu-Xue decoction (DBD) is a traditional Chinese medicine prescription clinically employed for diabetic nephropathy (DN). However, the components and pharmacological mechanisms of DBD against DN remain incompletely understood. PurposeTo clarify the beneficial effect of DBD on DN and to explore its nephroprotective effect's probable mechanism and the main components. MethodsA diabetic mice model was established by feeding a high-fat diet (HFD) and intraperitoneal injections of streptozotocin (STZ, 40 mg‧kg-1). Subsequently, the mice were maintained on a HFD and administered with DBD. The benefits of DBD against DN were comprehensively assessed by monitoring energy and water intake, blood glucose and lipids, renal functions and pathological status. The UPLC-MS/MS was measured to detect chemical constituents in DBD and absorbed components in DBD-treated plasma under physiological and pathological states. Network pharmacology was employed to forecast the probable pathways of DBD intervention in DN, with subsequent validation of these predictions through testing biochemical parameters, anti-glycation and ELISA assays, immunofluorescence, immunohistochemistry, and western blotting. Then, a chemical derivatization method paired with UPLC-MS/MS analysis was performed to detect the carbonyl compounds in renal tissue. Finally, the main components of DBD against DN were screened by anti-glycation and MTT assays. ResultsDBD regulated energy and water intakes, glucose and lipid metabolism disorders, renal dysfunction, glomerular filtration rate, renal interstitial glycogen accumulation and fibrosis in HFD/STZ-induced DN mice. A total of 129 distinct chemical constituents in DBD were characterized, of which 28 were detected in the DBD-treated plasma under a pathological state. The network pharmacological results suggested AGEs/RAGE and its downstream pathway may be a potential pathway for DBD intervention in DN. Further experiments confirmed that DBD reduced renal oxidative stress by modulating the AGEs/RAGE pathway. Moreover, 21 differential carbonyl compounds were detected between normal and DN mice, and DBD significantly modulated 16. Ultimately, seven components were screened out in DBD, which may be the main components of DBD regulating carbonyl compounds metabolic profile and AGEs/RAGE pathway. ConclusionOur findings suggested for the first time that DBD could regulate the carbonyl compounds metabolic profile and AGEs/RAGE signaling pathway to ameliorate DN.

Corilagin alleviates podocyte injury in diabetic nephropathy by regulating autophagy via the SIRT1-AMPK pathway.

Diabetic nephropathy (DN) is the most frequent chronic microvascular consequence of diabetes, and podocyte injury and malfunction are closely related to the development of DN. Studies have shown that corilagin (Cor) has hepatoprotective, anti-inflammatory, antibacterial, antioxidant, anti-hypertensive, anti-diabetic, and anti-tumor activities. To explore the protective effect of Cor against podocyte injury in DN mice and the underlying mechanisms. Streptozotocin and a high-fat diet were combined to generate DN mice models, which were then divided into either a Cor group or a DN group (n = 8 in each group). Mice in the Cor group were intraperitoneally injected with Cor (30 mg/kg/d) for 12 wk, and mice in the DN group were treated with saline. Biochemical analysis was used to measure the blood lipid profiles. Hematoxylin and eosin staining was used to detect pathological changes in kidney tissue. Immunohistochemistry and Western blotting were used to assess the protein expression of nephrin and podocin. Mouse podocyte cells (MPC5) were cultured and treated with glucose (5 mmol/L), Cor (50 μM), high glucose (HG) (30 mmol/L), and HG (30 mmol/L) plus Cor (50 μM). Real-time quantitative PCR and Western blotting were performed to examine the effects of Cor on podocyte autophagy. Compared with the control group, the DN mice models had increased fasting blood glucose, glycosylated hemoglobin, triglycerides, and total cholesterol, decreased nephrin and podocin expression, increased apoptosis rate, elevated inflammatory cytokines, and enhanced oxidative stress. All of the conditions mentioned above were alleviated after intervention with Cor. In addition, Cor therapy improved SIRT1 and AMPK expression (P < 0.001), inhibited reactive oxygen species and oxidative stress, and elevated autophagy in HG-induced podocytes (P < 0.01). Cor alleviates podocyte injury by regulating autophagy via the SIRT1-AMPK pathway, thereby exerting its protective impact on renal function in DN mice.

Berberine Inhibits KLF4 Promoter Methylation and Ferroptosis to Ameliorate Diabetic Nephropathy in Mice.

Inflammation, oxidative stress, fibrosis, and ferroptosis play important roles in diabetic nephropathy development. Krüppel-like factor 4 (KLF4) is a transcriptional factor, which regulates multiple cell processes and is involved in diabetic nephropathy. Berberine has various biological activities, including anti-inflammation, antioxidative stress, and antiferroptosis. Berberine has been shown to inhibit diabetic nephropathy, but whether it involves KLF4 and ferroptosis remains unknown. We established a diabetic nephropathy mice model and administered berberine to the mice. The kidney function, renal structure and fibrosis, expression of KLF4 and DNA methylation enzymes, DNA methylation of the KLF4 promoter, mitochondria structure, and expression of oxidative stress and ferroptosis markers were analyzed. Berberine rescued kidney function and renal structure and prevented renal fibrosis in diabetic nephropathy mice. Berberine suppressed the expression of DNMT1 and DNMT2 and upregulated KLF4 expression by preventing KLF4 promoter methylation. Berberine inhibited the expression of oxidative stress and ferroptosis markers, maintained mitochondria structure, and prevented ferroptosis. Berberine ameliorates diabetic nephropathy by inhibiting Klf4 promoter methylation and ferroptosis.

DMDD, isolated from Averrhoa carambola L., ameliorates diabetic nephropathy by regulating endoplasmic reticulum stress-autophagy crosstalk

BackgroundStudies have shown that Averrhoa carambola L. possesses therapeutic potential for diabetes and related complications. However, the specific beneficial effects and molecular mechanisms of 2-dodecyl-6-meth-oxycyclohexa-2,5-diene-1,4-dione (DMDD) isolated from Averrhoa carambola L. on diabetic nephropathy (DN) require further investigation.Methods80 C57BL/6 J male mice were subjected to a 1-week adaptive feeding, followed by a high-fat diet and intraperitoneal injection of 100 mg/kg streptozotocin (STZ) to construct an in vivo DN model. Additionally, human renal proximal tubular epithelial cells (HK-2) induced by high glucose (HG) were used as an in vitro DN model. The expression levels of epithelial-mesenchymal transition (EMT), endoplasmic reticulum stress (ERS), and autophagy-related proteins in renal tubular cells were detected by Western Blot, flow cytometry, immunofluorescence, and enzyme-linked immunosorbent assay (ELISA) staining. Transcriptome analysis revealed was conducted to elucidate the specific mechanism of by which DMDD mitigates DN by inhibiting ERS and autophagy. HK-2 cells were transfected with IRE1α overexpression lentivirus to reveal the role of IRE1α overexpression in HG-induced HK-2.ResultsThe experimental data showed that DMDD significantly reduced blood glucose levels and improved renal pathological alterations in DN mice. Additionally, DMDD inhibited the calcium (Ca2+) pathway, manifested by decreased autophagosome formation and downregulation of LC3II/I, Beclin-1, and ATG5 expression. Moreover, in HG-induced HK-2 cells, DMDD suppressed the overexpression of GRP78, CHOP, LC3II/I, Beclin1, and ATG5. Notably, IRE1α overexpression significantly increased autophagy incidence; however, DMDD treatment subsequently reduced the expression of LC3II/I, Beclin1, and ATG5.ConclusionDMDD effectively inhibits excessive ERS and autophagy, thereby reducing renal cell apoptosis through the IRE1α pathway and Ca 2+ pathway.

Shionone Inhibits Glomerular Fibirosis by Suppressing NLRP3 Related Inflammasome though SESN2-NRF2/ HO-1 Pathway.

Diabetic nephropathy (DN) is the most common and serious complication of diabetes mellitus. Shionone (SH), an important triterpenoid compound in the root extract of Aster, might exert a protective effect in DN mice and high glucose cultivated glomerular podocytes. The current study aimed to unravel the underlying mechanism by which SH mitigates DN. We postulate that SH stimulates the expression of sestrin-2 (SESN2), a pivotal stress-inducible protein in the anti-inflammasome machinery. We utilized high-fat diet combined with streptozotocin (55 mg/kg intraperitoneal) for DN mice model, and high glucose (30 mM, 48 hours) cultured glomerular podocytes for DN cell model to evaluate the effect of SH. We also preformed experimentation on SESN2 deficiency models (SESN2 knockout mice and SESN2 siRNA in cells) to further prove our hypothesis. The results demonstrated that SH effectively suppressed glomerular fibrosis, induced adenosine monophosphate-activated protein kinase (AMPK) phosphorylation, and inhibited NLR family pyrin domain containing 3 (NLRP3) activation. Furthermore, our findings revealed that SH exerted its anti-inflammatory effect through Sesn2-dependent nuclear factor erythroid 2-related factor 2 (Nrf2) nuclear translocation and subsequent activation of its downstream target heme oxygenase-1 (HO-1). In summary, our findings suggest that SH serves as a promising therapeutic agent for the treatment of DN-related glomerular fibrosis. SH enhances the expression of SESN2, attenuates α-smooth muscle actin accumulation, and suppresses NLRP3-related inflammation through the Nrf2/HO-1 signaling pathway.

WTAP and METTL14 regulate the m6A modification of DKK3 in renal tubular epithelial cells of diabetic nephropathy

Diabetic nephropathy (DN) is an important cause of death in diabetes patients, which is mainly due to its complex pathogenesis. Here, we explored the role of N6-methyladenosine (m6A) RNA methylation in DN development. Renal tubular epithelial cells from DN patients and experimental DN mice treated with streptozotocin (STZ) exhibited a considerable increase in METTL14 and WTAP expression as well as overall m6A methylation. Knocking down the expression of METTL14 and WTAP inhibited the migration and proliferation of tubular epithelial cells. MeRIP-seq analysis of the renal tissues of DN patients revealed that the genes with elevated m6A methylation were concentrated in the Wnt/β-Catenin signaling pathway. Dickkopf homolog 3 (DKK3) was screened out as the gene with the most significant increase in m6A methylation. In addition, the expression change pattern of DKK3 under DN circumstances is in line with those of METTL14 and WTAP. DKK3's m6A methylation sites were confirmed to be located in the 3′UTR region, which is how METTL14 and WTAP improved DKK3's mRNA stability. Finally, YTHDF1, a m6A reader, was demonstrated to recognize m6A-methylated DKK3 and promote DKK3 expression.

CD38 deficiency prevents diabetic nephropathy by inhibiting lipid accumulation and oxidative stress through activation of the SIRT3 pathway.

Diabetic nephropathy (DN) is one of the most common complications of diabetes. Our previous study showed that CD38 knockout (CD38KO) mice had protective effects on many diseases. However, the roles and mechanisms of CD38 in DN remain unknown. Here, DN mice were generated by HFD feeding plus streptozotocin (STZ) injection in male CD38KO and CD38flox mice. Mesangial cells (SV40 MES 13 cells) were used to mimic the injury of DN with palmitic acid (PA) treatment in vitro. Our results showed that CD38 expression was significantly increased in kidney of diabetic CD38flox mice and SV40 MES 13 cells treated with PA. CD38KO mice were significantly resistant to diabetes-induced renal injury. Moreover, CD38 deficiency markedly decreased HFD/STZ-induced lipid accumulation, fibrosis and oxidative stress in kidney tissue. In contrast, overexpression of CD38 aggravated PA-induced lipid accumulation and oxidative stress. CD38 deficiency increased expression of SIRT3, while overexpression of CD38 decreased its expression. More importantly, 3-TYP, an inhibitor of SIRT3, significantly enhanced PA-induced lipid accumulation and oxidative stress in CD38 overexpressing cell lines. In conclusion, our results demonstrated that CD38 deficiency prevented DN by inhibiting lipid accumulation and oxidative stress through activation of the SIRT3 pathway.

Neuregulin 4 Attenuates Podocyte Injury and Proteinuria in Part by Activating AMPK/mTOR-Mediated Autophagy in Mice.

In this study, we investigate the effect of neuregulin 4 (NRG4) on podocyte damage in a mouse model of diabetic nephropathy (DN) and we elucidate the underlying molecular mechanisms. In vivo experiments were conducted using a C57BL/6 mouse model of DN to determine the effect of NRG4 on proteinuria and podocyte injury, and in vitro experiments were performed with conditionally immortalized mouse podocytes treated with high glucose and NRG4 to assess the protective effects of NRG4 on podocyte injury. Autophagy-related protein levels and related signaling pathways were evaluated both in vivo and in vitro. The involvement of the adenosine monophosphate-activated protein kinase (AMPK)/mammalian target of rapamycin (mTOR) pathway was detected using chloroquine or AMPK inhibitors. The results showed that the AMPK/mTOR pathway was involved in the protective roles of NRG4 against high glucose-mediated podocyte injury. Also, NRG4 significantly decreased albuminuria in DN mice. PAS staining indicated that NRG4 mitigated glomerular volume and mesangium expansion in DN mice. Consistently, western blot and RT-PCR analyses confirmed that NRG4 decreased the expression of pro-fibrotic molecules in the glomeruli of DN mice. The immunofluorescence results showed that NRG4 retained expression of podocin and nephrin, whereas transmission electron microscopy revealed that NRG4 alleviated podocyte injury. In DN mice, NRG4 decreased podocyte apoptosis and increased expression of nephrin and podocin, while decreasing the expression of desmin and HIF1α. Overall, NRG4 improved albuminuria, glomerulosclerosis, glomerulomegaly, and hypoxia in DN mice. The in vitro experiments showed that NRG4 inhibited HG-induced podocyte injury and apoptosis. Furthermore, autophagy of the glomeruli decreased in DN mice, but reactivated following NRG4 intervention. NRG4 intervention was found to partially activate autophagy via the AMPK/mTOR signaling pathway. Consequently, when the AMPK/mTOR pathway was suppressed or autophagy was inhibited, the beneficial effects of NRG4 intervention on podocyte injury were diminished. These results indicate that NRG4 intervention attenuates podocyte injury and apoptosis by promoting autophagy in the kidneys of DN mice, in part, by activating the AMPK/mTOR signaling pathway.

Vaccarin suppresses diabetic nephropathy through inhibiting the EGFR/ERK1/2 signaling pathway.

Diabetic nephropathy (DN) is recognized as one of the primary causes of chronic kidney disease and end-stage renal disease. Vaccarin (VAC) confers favorable effects on cardiovascular and metabolic diseases, including type 2 diabetes mellitus (T2DM). Nonetheless, the potential role and mechanism of VAC in the etiology of DN have yet to be completely elucidated. In this study, a classical mouse model of T2DM is experimentally induced via a high-fat diet (HFD)/streptozocin (STZ) regimen. Renal histological changes are assessed via H&E staining. Masson staining and immunohistochemistry (IHC) are employed to assess renal fibrosis. RT-PCR is utilized to quantify the mRNA levels of renal fibrosis, oxidative stress and inflammation markers. The levels of malondialdehyde (MDA) and reactive oxygen species (ROS), as well as the content of glutathione peroxidase (GSH-Px), are measured. The protein expressions of collagen I, TGF-β1, α-SMA, E-cadherin, Nrf2, catalase, SOD3, SOD2, SOD1, p-ERK, p-EGFR (Y845), p-EGFR (Y1173), p-NFκB P65, t-ERK, t-EGFR and t-NFκB P65 are detected by western blot analysis. Our results reveal that VAC has a beneficial effect on DN mice by improving renal function and mitigating histological damage. This is achieved through its inhibition of renal fibrosis, inflammatory cytokine overproduction, and ROS generation. Moreover, VAC treatment effectively suppresses the process of epithelial-mesenchymal transition (EMT), a crucial characteristic of renal fibrosis, in high glucose (HG)-induced HK-2 cells. Network pharmacology analysis and molecular docking identify epidermal growth factor receptor (EGFR) as a potential target for VAC. Amino acid site mutations reveal that Lys-879, Ile-918, and Ala-920 of EGFR may mediate the direct binding of VAC to EGFR. In support of these findings, VAC reduces the phosphorylation levels of both EGFR and its downstream mediator, extracellular signal-regulated kinase 1/2 (ERK1/2), in diabetic kidneys and HG-treated HK-2 cells. Notably, blocking either EGFR or ERK1/2 yields renal benefits similar to those observed with VAC treatment. Therefore, this study reveals that VAC attenuates renal damage via inactivation of the EGFR/ERK1/2 signaling axis in T2DM patients.

Myricetin alleviates renal tubular epithelial-mesenchymal transition via NOX4/NF-κB/snail axis in diabetic nephropathy based on network pharmacology analysis

Diabetic nephropathy (DN), a leading cause of end-stage renal disease, remains a formidable challenge in diabetes management due to the complex nature of its pathogenesis, particularly the epithelial-mesenchymal transition (EMT) process. Our innovative study leverages network pharmacology to explore the therapeutic potentials of Myricetin, a natural flavonoid, focusing on its effects against NOX4, a critical mediator in DN progression. This investigation marks a pioneering approach by integrating network pharmacology to predict and elucidate the inhibitory relationship between Myricetin and NOX4. Utilizing a high-fat diet/streptozotocin (HFD/STZ) induced DN mouse model, we delved into the effects of Myricetin on renal EMT processes. Through network pharmacology analyses coupled with molecular docking studies, we identified and confirmed Myricetin's binding efficacy to NOX4. Extensive in vitro and in vivo experiments further established Myricetin's significant impact on mitigating EMT by modulating the NOX4-NF-κB-Snail signaling pathway. Results from our research demonstrated notable improvements in renal function and reductions in tissue fibrosis among treated HFD/STZ mice. By curtailing NOX4 expression, Myricetin effectively reduced reactive oxygen species (ROS) production, thereby inhibiting NF-κB activation and subsequent Snail expression, crucial steps in the EMT pathway. Supported by both theoretical predictions and empirical validations, this study unveils the mechanism underlying Myricetin's modulation of EMT in DN through disrupting the NOX4-NF-κB-Snail axis. These findings not only contribute a new therapeutic avenue for DN treatment but also underscore the utility of network pharmacology in advancing drug discovery processes.

Ramulus Mori (Sangzhi) Alkaloids Alleviate Diabetic Nephropathy through Improving Gut Microbiota Disorder.

Diabetic nephropathy (DN), one of the leading causes of end-stage kidney failure worldwide, is closely associated with high mortality in diabetic patients. However, therapeutic drugs for DN are still lacking. Ramulus Mori alkaloids (SZ-A), an effective component of alkaloids extracted from Ramulus Mori, have been found to improve glucose and lipid metabolism to mitigate diabetes and obesity; however, few studies have focused on their effects on DN progression. Thus, we investigated the protective role of SZ-A on DN through 16S rRNA sequencing, non-targeted metabolomics, and fecal microbiota transplantation (FMT) experiments. To address our hypothesis, we established the DN mouse model by combining a high-fat diet (HFD) with streptozotocin (STZ) injection. Herein, we demonstrated that SZ-A supplementation was recalcitrant to renal injury in DN mice, improving glomerular morphology, reversing the blood biochemistry parameters, and ameliorating podocyte injury. Importantly, the composition of the gut microbiota altered after SZ-A treatment, especially with the elevated abundance of Dubosiella and the increased level of serum pentadecanoic acid. FMT experiments further revealed that the gut microbiota exerted critical effects in mediating the beneficial roles of SZ-A. In vitro experiments proved that pentadecanoic acid administration improved podocyte apoptosis induced by AGEs. Taken together, SZ-A play a renoprotective role, possibly through regulating the gut microbiota and promoting pentadecanoic acid production. Our current study lends support to more extensive clinical applications of SZ-A.

Tirzepatide alleviates oxidative stress and inflammation in diabetic nephropathy via IL-17 signaling pathway.

Oxidative stress (OS) and inflammation play essential roles in the development of diabetic nephropathy (DN). Tirzepatide (TZP) has a protective effect in diabetes. However, its underlying mechanism in DN remains unclear. DN model mice were induced by intraperitoneal injection of streptozotocin (STZ; 60mg/kg), followed by administration of different doses of TZP (3 and 10nmol/kg) via intraperitoneal injection for 8weeks. The effects of TZP on DN were evaluated by detecting DN-related biochemical indicators, kidney histopathology, apoptosis, OS, and inflammation levels. Additionally, to further reveal the potential mechanism, we investigated the role of TZP in modulating the IL-17 pathway. TZP reduced serum creatinine (sCR), blood urea nitrogen (BUN), and advanced glycosylation end products (AGEs) levels, while simultaneously promoting insulin secretion in diabetic mice. Additionally, TZP attenuated tubular and glomerular injury and reduced renal apoptosis levels. Further studies found that TZP increased the levels of SOD and CAT, and decreased MDA. Meanwhile, TZP also reduced the expression of pro-inflammatory cytokines (TNF-α, IL-1β, and IL-6) in both mouse serum and kidney homogenates. TZP effectively inhibited the IL-17 pathway, and subsequent intervention with an IL-17 pathway agonist (IL-17A) reversed the suppressive effects of TZP on OS and inflammation. TZP can improve DN by inhibiting OS and inflammation through the suppression of the IL-17 pathway.