High glucose evokes an intrinsic proapoptotic signaling pathway in mesangial cells

The Effects of Apigenin in the Treatment of Diabetic Nephropathy: A Systematic Review of Non-clinical Studies

PURPOSE

Diabetes is one of the important and growing diseases in the world. Among the most common diabetic complications are renal adverse effects. The use of apigenin may prevent the development and progression of diabetes-related injuries. The current study aims to review the effects of apigenin in the treatment of diabetic nephropathy.

METHODS

In this review, a systematic search was performed based on PRISMA guidelines for obtaining all relevant studies on "the effects of apigenin against diabetic nephropathy" in various electronic databases up to September 2022. Ninety-one articles were obtained and screened in accordance with the predefined inclusion and exclusion criteria. Seven eligible articles were finally included in this review.

RESULTS

The experimental findings revealed that hyperglycemia led to the decreased cell viability of kidney cells and body weight loss and an increased kidney weight of rats; however, apigenin administration had a reverse effect on these evaluated parameters. It was also found that hyperglycemia could induce alterations in the biochemical and renal function-related parameters as well as histopathological injuries in kidney cells or tissue; in contrast, the apigenin administration could ameliorate the hyperglycemia-induced renal adverse effects.

CONCLUSION

The results indicated that the use of apigenin could mitigate diabetes-induced renal adverse effects, mainly through its antioxidant, anti-apoptotic, and anti-inflammatory activities. Since the findings of this study are based on experimental studies, suggesting the use of apigenin (as a nephroprotective agent) against diabetic nephropathy requires further clinical studies.

Pericyte Loss in Diseases

Pericytes are specialized cells located in close proximity to endothelial cells within the microvasculature. They play a crucial role in regulating blood flow, stabilizing vessel walls, and maintaining the integrity of the blood-brain barrier. The loss of pericytes has been associated with the development and progression of various diseases, such as diabetes, Alzheimer's disease, sepsis, stroke, and traumatic brain injury. This review examines the detection of pericyte loss in different diseases, explores the methods employed to assess pericyte coverage, and elucidates the potential mechanisms contributing to pericyte loss in these pathological conditions. Additionally, current therapeutic strategies targeting pericytes are discussed, along with potential future interventions aimed at preserving pericyte function and promoting disease mitigation.

The role of Chinese herbal medicine in the treatment of diabetic nephropathy by regulating endoplasmic reticulum stress

Diabetic nephropathy (DN), a prevalent microvascular complication of diabetes mellitus, is the primary contributor to end-stage renal disease in developed countries. Existing clinical interventions for DN encompass lifestyle modifications, blood glucose regulation, blood pressure reduction, lipid management, and avoidance of nephrotoxic medications. Despite these measures, a significant number of patients progress to end-stage renal disease, underscoring the need for additional therapeutic strategies. The endoplasmic reticulum (ER) stress response, a cellular defense mechanism in eukaryotic cells, has been implicated in DN pathogenesis. Moderate ER stress can enhance cell survival, whereas severe or prolonged ER stress may trigger apoptosis. As such, the role of ER stress in DN presents a potential avenue for therapeutic modulation. Chinese herbal medicine, a staple in Chinese healthcare, has emerged as a promising intervention for DN. Existing research suggests that some herbal remedies may confer renoprotective benefits through the modulation of ER stress. This review explores the involvement of ER stress in the pathogenesis of DN and the advancements in Chinese herbal medicine for ER stress regulation, aiming to inspire new clinical strategies for the prevention and management of DN.

The Mechanism of Hyperglycemia-Induced Renal Cell Injury in Diabetic Nephropathy Disease: An Update

Diabetic Nephropathy (DN) is a serious complication of type I and II diabetes. It develops from the initial microproteinuria to end-stage renal failure. The main initiator for DN is chronic hyperglycemia. Hyperglycemia (HG) can stimulate the resident and non-resident renal cells to produce humoral mediators and cytokines that can lead to functional and phenotypic changes in renal cells and tissues, interference with cell growth, interacting proteins, advanced glycation end products (AGEs), etc., ultimately resulting in glomerular and tubular damage and the onset of kidney disease. Therefore, poor blood glucose control is a particularly important risk factor for the development of DN. In this paper, the types and mechanisms of DN cell damage are classified and summarized by reviewing the related literature concerning the effect of hyperglycemia on the development of DN. At the cellular level, we summarize the mechanisms and effects of renal damage by hyperglycemia. This is expected to provide therapeutic ideas and inspiration for further studies on the treatment of patients with DN.

Calcium dobesilate efficiency in the treatment of diabetic kidney disease through suppressing MAPK and chemokine signaling pathways based on clinical evaluation and network pharmacology

Aims: To evaluate the effectiveness and potential mechanism of calcium dobesilate (CaD) in diabetic kidney disease (DKD) patients.

Methods: We searched for available randomized controlled studies on DKD patients’ treatment with CaD through open databases. Continuous variables were expressed as standardized mean difference (SMD) with a 95% confidence interval (CI). The putative targets and possible pathways of CaD on DKD were analyzed by network pharmacology. Molecular docking was employed to verify the match between CaD and the target genes.

Results: In the meta-analysis, 42 trials were included, involving 3,671 DKD patients, of which 1,839 received CaD treatment in addition to conventional treatment, while 1,832 received conventional treatment. Compared with routine therapy, the levels of serum creatinine (Scr) and blood urea nitrogen (BUN) significantly decreased in the CaD treatment (early stage of DKD, Scr: p < 0.00001; BUN: p < 0.0001; clinical stage of DKD, Scr: p < 0.00001; BUN: p < 0.00001; kidney failure stage, Scr: p = 0.001; BUN: p = 0.004). The levels of serum cystatin C (Cys-C), urine levels of molecules reflecting kidney function (urinary albumin excretion rate (UAER) and micro glycoprotein), and inflammatory factors [hypersensitive c-reactive protein (hs-CRP)] were reduced compared with control groups, while glomerular filtration rate (GFR) was increased in patients treated with CaD for 12 weeks. CaD also showed a better effect on improving endothelial function. Network pharmacology results showed that the interaction pathway between CaD and DKD was mainly enriched in MAPK and chemokine signaling pathways. AKT1, CASP3, IGF1, MAPK8, and CCL5 might be the key targets for CaD in treating DKD.

Conclusion: Combination with CaD is effective and safe in patients with DKD. Inhibition of MAPK and chemokine signaling pathways might be vital in treating CaD in DKD patients.

Thalidomide Mitigates Apoptosis via Endoplasmic Reticulum Stress in Diabetic Nephropathy

BACKGROUND

Previous studies have shown that endoplasmic reticulum (ER) stress is related to the apoptosis in the development of diabetic nephropathy (DN) and thalidomide (Thd) has renal-protective effects by suppressing inflammation and proliferation of MCs in DN. However, the effect of Thd on the apoptosis of MCs in DN remains largely unclear. The present research is designed to explore the effect of Thd on apoptosis in DN and the related mechanisms.

OBJECTIVE

The study is designed to examine the effect and mechanism of Thd on apoptosis in type 2 diabetic mice and high glucose (HG)-induced MCs.

METHOD

We first evaluated the ER stress markers and apoptosis-related proteins with the treatment of Thd in type 2 diabetic mice and MCs in vitro under HG conditions. MTT assay was used to assess cell viability. Additionally, we evaluated the effect of Thd treatment upon MC apoptosis through flow cytometry. Real-time polymerase chain reaction (RT-PCR) and Western blot were performed to evaluate genes and protein expression related to ER stress and apoptosis.

RESULTS

The levels of blood urea BUN, CREA, Urine albumin, and UACR in diabetic mice were significantly reduced after 8 weeks of intervention with Thd. And also, there were upregulated glucose-regulated protein 78 (GRP78), Caspase-12, and downregulated B-cell lymphoma 2 (Bcl-2) in glomeruli of DN mice. In vitro, compared with the HG group, MC apoptosis reduced dramatically with Thd treatment along with upregulation of Bcl-2 and downregulation of Bax. At the same time, ER stress markers GRP78, C/EBP homologous protein (CHOP), and Caspase-12 were also mitigated following the Thd treatment.

CONCLUSION

The present study indicates that Thd might reduce the ER stress in DN via downregulating of GRP78, CHOP, and Caspase12 expression, ultimately mitigating MCs apoptosis.

ChREBP deficiency alleviates apoptosis by inhibiting TXNIP/oxidative stress in diabetic nephropathy

AIMS

In the present study, we investigated the effect of carbohydrate responsive element binding protein (ChREBP) on the TXNIP/oxidative stress and apoptosis in diabetic nephropathy.

METHODS

ChREBP^-/- mice (8-week old) were produced using the CRISPR/Cas9 gene editing approach. Diabetes was induced in C57BL/6 mice with streptozotocin. HK-2 cells was transfected with plasmid containing either ChREBP shRNA or TXNIP siRNA.

RESULTS

Renal expression of ChREBP and thioredoxin-interacting protein (TXNIP) was increased in patients with type 2 diabetes mellitus (T2DM) and diabetic mice. ChREBP deficiency improved renal function, apoptosis as well as endoplasmic reticulum (ER) stress in diabetic mice. In addition, ChREBP deficiency prevented expression levels of TXNIP and NADPH oxidase 4 (Nox4), 8-hydroxydeoxyguanosine (8-OHdG) and heme oxygenase-1 (HO-1) in diabetic kidneys. The increased urinary 8-OHdG level induced by diabetes was also attenuated in ChREBP deficiency mice. Similarly, HG was shown to induce ChREBP expression and nuclear translocation in HK-2 cells. HG-induced apoptosis was inhibited by transfection of ChREBP shRNA plasmid. Moreover, we found that knockdown of ChREBP suppressed HG-induced TXNIP and Nox4 expression, reactive oxygen species (ROS) generation and ER stress in HK-2 cells. Furthermore, TXNIP knockdown effectively abrogated HG-induced apoptosis in HK-2 cells.

CONCLUSIONS

These results suggest that ChREBP deficiency prevents diabetes-induced apoptosis via inhibiting oxidative stress and ER stress, highlighting ChREBP as a potential therapy target for diabetic nephropathy.

Circ_0000491 Promotes Apoptosis, Inflammation, Oxidative Stress, and Fibrosis in High Glucose-Induced Mesangial Cells by Regulating miR-455-3p/Hmgb1 Axis

BACKGROUND

Diabetic nephropathy (DN) is a severe microvascular complication of diabetes. Recently, many circular RNAs can exert crucial roles in DN progression. This study intended to explore the role and mechanism of circ_0000491 in DN.

METHODS

The DN mouse model was constructed by streptozotocin injection, and the DN cell model was established using high glucose (HG) treatment in mouse mesangial cells (SV40-MES13). The expression of circ_0000491 and microRNA-455-3p (miR-455-3p) was detected by quantitative real-time polymerase chain reaction. Cell apoptosis was evaluated by flow cytometry. The expression levels of high-mobility group box 1 (Hmgb1) protein, apoptosis-related proteins, and fibrosis-related proteins were examined by the Western blot assay. The release of inflammatory cytokines was assessed by enzyme-linked immunosorbent assay. The oxidative stress factors were analyzed by corresponding kits. The predicted interaction between miR-455-3p and circ_0000491 or Hmgb1 was verified by dual-luciferase reporter assay and RNA immunoprecipitation assay.

RESULTS

Circ_0000491 was overexpressed in the DN mouse model and HG-induced SV40-MES13 cells. Knockdown of circ_0000491 weakened HG-induced apoptosis, inflammation, oxidative stress, and fibrosis in SV40-MES13 cells. miR-455-3p was a direct target of circ_0000491, and miR-455-3p inhibition could reverse the role of circ_0000491 silencing in HG-induced SV40-MES13 cells. Moreover, Hmgb1 was a target gene of miR-455-3p, and miR-455-3p played a protective role against HG-induced cell injury by targeting Hmgb1. In addition, circ_0000491 regulated Hmgb1 expression by sponging miR-455-3p.

CONCLUSION

Circ_0000491 knockdown inhibited HG-induced apoptosis, inflammation, oxidative stress, and fibrosis in SV40-MES13 cells by regulating miR-455-3p/Hmgb1 axis.

MiR-17-5p downregulation alleviates apoptosis and fibrosis in high glucose-induced human mesangial cells through inactivation of Wnt/β-catenin signaling by targeting KIF23

Diabetic nephropathy (DN) remains the major cause of end-stage renal disease. MicroRNAs (miRNAs) have been reported to perform biological functions in many diseases. This investigation elucidated the biological role of miR-17-5p in DN. In this study, high glucose-cultured human mesangial cells (HMCs) were used as a cell model of DN. The miR-17-5p and KIF23 expression was measured by RT-qPCR. Cell apoptosis was detected by flow cytometry. The protein levels of apoptosis markers, fibrosis markers, and Wnt/β-catenin signaling-related genes were assessed using western blotting. The interaction of miR-17-5p with KIF23 was tested by a luciferase reporter assay. We found that miR-17-5p was upregulated in both DN patients and high glucose-treated HMCs. Silencing miR-17-5p attenuated the apoptosis and fibrosis in high glucose-treated HMCs. MiR-17-5p binds to KIF23 3'UTR and negatively regulates KIF23 expression. KIF23 knockdown could suppress the role of miR-17-5p inhibition in high glucose-treated HMCs. Additionally, inhibition of miR-17-5p activated Wnt/β-catenin signaling in HMCs through upregulating KIF23 expression. Suppression of Wnt/β-catenin signaling antagonized the effect of miR-17-5p in HMCs. In conclusion, miR-17-5p inhibition alleviates the apoptosis and fibrosis in high glucose-treated HMCs by targeting KIF23 activating Wnt/β-catenin signaling.

NADH/NAD+ Redox Imbalance and Diabetic Kidney Disease

Diabetic kidney disease (DKD) is a common and severe complication of diabetes mellitus. If left untreated, DKD can advance to end stage renal disease that requires either dialysis or kidney replacement. While numerous mechanisms underlie the pathogenesis of DKD, oxidative stress driven by NADH/NAD⁺ redox imbalance and mitochondrial dysfunction have been thought to be the major pathophysiological mechanism of DKD. In this review, the pathways that increase NADH generation and those that decrease NAD⁺ levels are overviewed. This is followed by discussion of the consequences of NADH/NAD⁺ redox imbalance including disruption of mitochondrial homeostasis and function. Approaches that can be applied to counteract DKD are then discussed, which include mitochondria-targeted antioxidants and mimetics of superoxide dismutase, caloric restriction, plant/herbal extracts or their isolated compounds. Finally, the review ends by pointing out that future studies are needed to dissect the role of each pathway involved in NADH-NAD⁺ metabolism so that novel strategies to restore NADH/NAD⁺ redox balance in the diabetic kidney could be designed to combat DKD.

Piperazine ferulate attenuates high glucose‑induced mesangial cell injury via the regulation of p66Shc

Diabetic nephropathy (DN) is a severe microvascular complication of diabetes. Hyperglycemia-induced glomerular mesangial cells injury is associated with microvascular damage, which is an important step in the development of DN. Piperazine ferulate (PF) has been reported to exert protective effects against the progression of DN. However, whether PF prevents high glucose (HG)-induced mesangial cell injury remains unknown. The aim of the present study was to investigate the effects of PF on HG-induced mesangial cell injury and to elucidate the underlying mechanisms. Protein and mRNA expression levels were determined via western blot analysis and reverse transcription-quantitative PCR, respectively. IL-6 and TNF-α levels were measured using ELISA. Reactive oxygen species levels and NF-κB p65 nuclear translation were determined via immunofluorescence analysis. Apoptosis was assessed by measuring lactate dehydrogenase (LDH) release, as well as using MTT and flow cytometric assays. The mitochondrial membrane potential of mesangial cells was determined using the JC-1 kit. The results revealed that LDH release were increased; however, cell viability and mitochondrial membrane potential were decreased in the HG group compared with the control group. These changes were inhibited after the mesangial cells were treated with PF. Moreover, PF significantly inhibited the HG-induced production of inflammatory cytokines and the activation of NF-κB in mesangial cells. PF also attenuated the HG-induced upregulation of the expression levels of fibronectin and collagen 4A1. Furthermore, the overexpression of p66^{Src homology/collagen (Shc)} abolished the protective effect of PF on HG-induced mesangial cell injury. In vivo experiments revealed that PF inhibited the activation of inflammatory signaling pathways, glomerular cell apoptosis and mesangial matrix expansion in diabetic mice. Collectively, the present findings demonstrated that PF attenuated HG-induced mesangial cells injury by inhibiting p66^Shc.

YAP mediates the interaction between the Hippo and PI3K/Akt pathways in mesangial cell proliferation in diabetic nephropathy

AIMS

Glomerular mesangial cell (MC) proliferation is one of the main pathological changes in diabetic nephropathy (DN), but its mechanism needs further elaboration. The Hippo and PI3K/Akt signalling pathways are involved in the regulation of MC proliferation, but their relationship in hyperglycaemia-induced MC proliferation has not been reported.

METHODS

We used db/db mice and high-glucose-cultured mesangial cells to generate a diabetic nephropathy model. An MST1-knockdown plasmid was used to identify whether the PI3K/Akt pathway is linked to the Hippo pathway through MST1. LY294002 and SC79 were used to verify the role of the PI3K/Akt signalling pathway in MC cells. RNA silencing and overexpression were performed by using YAP and PTEN-expression/knockdown plasmids to investigate the function of YAP and PTEN, respectively, in the Hippo and PI3K/Akt signalling pathways.

RESULTS

By examining a potential feedback loop, we found decreased phosphorylation of MST1 and Lats1 and increased PI3K/Akt activation in db/db mice and high glucose-treated MCs, along with increased MC proliferation. The results of our gene silencing experiment proved PI3K/Akt-mediated intervention in the Hippo pathway and the regulatory effect of YAP on PI3K/Akt through PTEN.

CONCLUSIONS

The Hippo pathway is inhibited under diabetic conditions, leading to YAP activation and promoting MC proliferation. The PI3K/Akt pathway is activated through the inhibitory effect of YAP on its repressor, PTEN. Finally, activation of the PI3K/Akt pathway inhibits the Hippo pathway, resulting in nuclear YAP accumulation and accelerating MC proliferation and DN formation.

Mitochondria-Associated Endoplasmic Reticulum Membranes (MAMs) and Their Prospective Roles in Kidney Disease

Mitochondria-associated endoplasmic reticulum (ER) membranes (MAMs) serve as essential hubs for interorganelle communication in eukaryotic cells and play multifunctional roles in various biological pathways. A defect in ER-mitochondria signaling or MAMs dysfunction has pleiotropic effects on a variety of intracellular events, which results in disturbances of the mitochondrial quality control system, Ca2+ dyshomeostasis, apoptosis, ER stress, and inflammasome activation, which all contribute to the onset and progression of kidney disease. Here, we review the structure and molecular compositions of MAMs as well as the experimental methods used to study these interorganellar contact sites. We will specifically summarize the downstream signaling pathways regulated by MAMs, mainly focusing on mitochondrial quality control, oxidative stress, ER-mitochondria Ca2+ crosstalk, apoptosis, inflammasome activation, and ER stress. Finally, we will discuss how alterations in MAMs integrity contribute to the pathogenesis of kidney disease and offer directions for future research.

Triphala Ameliorates Nephropathy via Inhibition of TGF-β1 and Oxidative Stress in Diabetic Rats

INTRODUCTION

Advanced glycation end products, oxidative stress, and TGF-β expression play a crucial role in pathophysiology of diabetic nephropathy. Inhibition of oxidative stress and TGF-β expression by natural traditional medicines may give an economic and safe alternative treatment option. Triphala churna, a traditional medicine, has been proved to have potent antioxidant activity, and individual components of it have shown significant antidiabetic activity. Hence, the present study was designed to study the effect of Triphala churna in diabetic nephropathy in rats.

METHODS

Diabetes was induced in rats by administration of streptozotocin (55 mg/kg i.p.). Four weeks after induction of diabetes, the animals were treated with Triphala churna at the doses of 250, 500, and 1,000 mg/kg for next 4 weeks. Various biochemical and urine parameters such as glucose, creatinine, blood urea nitrogen (BUN), total protein, and albumin were assessed at the end of study. Creatinine clearance, BUN clearance, and glomerular filtration rate were determined. Oxidative stress parameters such as malondialdehyde, catalase, reduced glutathione, and superoxide dismutase were determined in kidney tissues. TGF-β1 expression was measured with ELISA, immunohistochemistry, and western blot techniques. Histopathology study was carried out with haemotoxylin and eosin, periodic acid-Schiff, and Masson's trichrome staining to determine histological changes.

RESULTS

Treatment with Triphala churna significantly improved urine parameters. Triphala churna treatment also improved plasma proteins, albumin, creatinine, and BUN levels. The oxidative stress was reduced in the kidney with the treatment of Triphala churna. Histopathological studies revealed that Triphala churna reduced kidney damage. Immunohistochemistry, ELISA, and western blotting study revealed that treatment with Triphala decreased the expression of TGF-β in kidney tissues.

CONCLUSION

From the results, it can be concluded that Triphala churna has a significant nephroprotective effect because of its capability of inhibiting oxidative stress and TGF-β in diabetes.

Identification of key genes and pathways in syphilis combined with diabetes: a bioinformatics study

We noticed that syphilis patients seem to be more susceptible to diabetes and the lesions often involve the kidneys, but the pathogenesis is not yet completely understood. In this study, microarray analysis was performed to investigate the dysregulated expressed genes (DEGs) in rabbit model of syphilis combined with diabetes. A total of 1045 genes were identified to be significantly differentially expressed, among which 571 were up-regulated and 474 were down-regulated (≥ 2.0fold, p < 0.05). Using the database visualization and integration discovery for the Kyoto Encyclopedia of Gene and Genome (KEGG) pathway enrichment analysis. The downregulated DEGs were significantly enriched for biosynthesis of antibiotics, carbon metabolism and protein digestion, while the upregulated DEGs were mainly enriched for cancer and PI3K-Akt signaling pathway. Molecular Complex Detection (MCODE) plugins were used to visualize protein–protein interaction (PPI) network of DEGs and Screening for hub genes and gene modules. ALB, FN1, CASP3, MMP9, IL8, CTGF, STAT3, IGF1, VCAM-1 and HGF were filtrated as the hub genes according to the degree of connectivity from the PPI network. To the best of our knowledge, this study is the first to comprehensively identify the expression patterns of dysregulated genes in syphilis combined with diabetes, providing a basis for revealing the underlying pathogenesis of syphilis combined with diabetes and exploring the goals of therapeutic intervention.

High Glucose Induces Mesangial Cell Apoptosis through miR-15b-5p and Promotes Diabetic Nephropathy by Extracellular Vesicle Delivery

Diabetic nephropathy (DN) is an increasing threat to human health and is regarded as an important public issue. The pathophysiologic mechanisms of DN are complicated. The initiating molecular events triggering the loss function in mesangial cells (MCs) in DN are not well known. In this cross-disciplinary study, transcriptome analysis of high glucose (HG)-treated mouse MCs (MMCs) using next-generation sequencing and systematic bioinformatics analyses indicated that miR-15b-5p and its downstream target B cell lymphoma 2 (BCL-2) contribute to HG-induced apoptosis in MMCs. HG elevated miR-15b-5p expression, which in turn decreased the translation of BCL-2, leading to MMC apoptosis under HG. Apoptosis of MCs was enhanced in the presence of extracellular vesicles isolated from the urine of type 2 diabetic patients with high levels of miR-15b-5p. Furthermore, increased levels of urinary miR-15b-5p were found in db/db mice and type 2 diabetic patients, and such levels correlated with low baseline kidney function and rapid decline in kidney function during a mean of follow-up period of 2.4 ± 0.1 years. Therefore, miR-15b-5p induced mesangial cells apoptosis by targeting BCL-2 under HG. miR-15b-5p has the potential to predict kidney injury in DN. Blocking the miR-15b-5p epigenetic regulatory network could be a potential therapeutic strategy to prevent mesangial apoptosis in DN.

Novel biphenyl diester derivative AB-38b inhibits NLRP3 inflammasome through Nrf2 activation in diabetic nephropathy

Inflammation reaction mediated by NLRP3 inflammasome and Nrf2-related oxidative stress are vital participants in the development of diabetic nephropathy (DN) and closely associated to kidney fibrosis. Nrf2, a known antioxidative transcription factor, has been reported to activate NLRP3 inflammasome through its downstream factors (HO-1, NQO1, etc.) recently. AB38b is a newly synthesized biphenyl diester derivative with a Nrf2 activation property. This research aims to evaluate the renal protective effects of AB-38b and to elucidate the anti-inflammation mechanisms involved. Type 2 diabetic mice induced by high fat diet with streptozocin (STZ) and high glucose-cultured mouse glomerular mesangial cells (GMCs) were used in current study. Results showed that administration of AB-38b improved the kidney function while attenuated renal fibrosis progression in diabetic mice together with reducing the extracellular matrix (ECM) accumulation of GMCs cultured in high glucose. Mechanistically, treatment with AB-38b significantly decreased the high level of NLRP3 inflammasome in diabetic condition by inhibiting the ROS/TXNIP/NLRP3 signaling pathway. And meanwhile, AB-38b treatment effectively improved Nrf2 signaling during diabetic condition. Furthermore, knocking down the gene expression of Nrf2 by siRNA in GMCs abolished the inhibition effect of AB-38b on NLRP3 inflammasome activation and ECM accumulation. Taken together, our data suggest that AB-38b was able to improve the renal function of diabetic mice, and the NLRP3 inflammasome inhibition effect of AB-38b was responsible for the renal protective effect. Further exploration indicate that Nrf2 plays pivotal role in AB-38b's attenuation of DN progression through inhibiting NLRP3 inflammasome activation.

Assessment of two novel renal tubular proteins in type 2 diabetic patients with nephropathy

Nephropathy is a common health issue associated with type 2 diabetes mellitus (T2DM). Treatment of diabetic nephropathy (DN) in an early stage can effectively inhibit its progression. Albuminuria is the currently accepted marker for detection of DN.This study aims to evaluate the urinary level of two novel renal tubular proteins (cyclophilin A and periostin) in patients with T2DM and among different nephropathy stages and also to validate the diagnostic accuracy of both cyclophilin A and periostin as potential markers for early prediction of DN relative to albuminuria.This cross-sectional study recruited 137 patients with T2DM, and they were divided based on their urinary albumin:creatinine ratio into T2DM with normoalbuminuria (group II), incipient T2DN with microalbuminuria (group III) and overt T2DN with macroalbuminuria (group IV) beside 41 healthy subjects as group I Cyclophilin A and periostin were measured in the urine using ELISA. Diagnostic accuracy of both markers was determined for prediction of DN via receiver operating characteristic curve analyses.Urinary cyclophilin A and periostin levels were significantly higher in DN groups when compared with T2DM with normoalbuminuria group. For prediction of incipient and overt DN, areas under the curve (AUCs) of periostin were 0.954, 0.997 and cyclophilin A were 0.914, 0.937, respectively. AUCs of periostin were higher than that for cyclophilin A with a significant AUC difference (p=0.022) in overt DN stage.Periostin and cyclophilin A could be regarded as a potential urinary biomarker for early prediction of DN. Periostin exhibits a higher diagnostic accuracy than urinary cyclophilin A specifically in overt DN stage.

Immune-associated renal disease found in caspase 3-deficient mice

Caspase (CASP) 3 is known as a representative effector CASP of apoptosis and recently as a mediator in inflammatory cell death called pyroptosis. Interestingly, homozygotes of Casp3 knockout (KO) mice with 129-background show complete embryonic lethality; however, some of those with C57BL/6 (B6)-background (B6.129S1-Casp3^tm1Flv/J) survived at a lower rate (KO, 11%; WT, 22%), developing immune abnormality-associated renal phenotypes. Homozygotes of Casp3 KO mice with B6-background that survived for 8-12 months showed abnormality in the kidney and spleen but not in other organs. Briefly, these Casp3 KO kidneys showed proliferative glomerular lesions characterized by increased cells, matrices, immune complex depositions containing IgA and complement 3 in the mesangial area, podocyte injuries and inflammatory cell infiltrations in the tubulointerstitium. However, severe membranous lesion or renal dysfunction was not observed. Increased expression of inflammation-associated gene sets and inflammatory Casps, including Casp12, was observed in these Casp3 KO kidneys. Moreover, these Casp3 KO mice showed mild splenomegaly compared with WT mice. Thus, the long-surviving Casp3 KO mice with B6-background developed renal lesions with altered immune conditions. CASP3 deficiency and aging factors could affect this phenotype by altering the function and/or development of each cell in the kidney and immune organs.

Vindoline-A Natural Product from Catharanthus Roseus Reduces Hyperlipidemia and Renal Pathophysiology in Experimental Type 2 Diabetes

Cardiovascular diseases (CVDs) and kidney diseases in diabetes are linked to increased mortality and morbidity. The aim of this study was to evaluate the effect of vindoline derived from Catharanthus roseus in diabetes-induced CVDs and kidney disease through assessing inflammation, oxidative stress, hyperlipidaemia and kidney function parameters. Type 2 diabetes was induced in male Wistar rats by 10% fructose water intake for two weeks, followed by a single intraperitoneal injection of 40mg/kg body weight of streptozotocin (STZ). Six groups (n = 8) of randomly divided rats received vindoline (20mg/kg) or glibenclamide (5mg/kg) daily for 6 weeks via oral gavage. Lipid profile markers and markers of atherogenic index were decreased in diabetic rats after treatment with vindoline and glibenclamide. The levels of urea were significantly increased in the diabetic control group (13.66 ± 0.9) compared to the diabetic groups treated with vindoline and glibenclamide (10.62 ± 0.6 and 10.82 ± 0.8), respectively. Vindoline did not significantly alter the levels of inflammatory cytokines; however glibenclamide lowered the levels of TNF-α in kidney and heart tissues. Vindoline improved the ferric reducing antioxidant power in diabetic hearts, while superoxide dismutase (SOD) oxygen radical absorbance capacity was increased in the kidneys. Lipid peroxidation was reduced when compared to the diabetic controls. Vindoline restored the structure of the renal parenchyma and was accompanied by significant decrease in the expression of caspase 9 in diabetic rats when compared to the diabetic controls.

Renal effects of a sodium-glucose cotransporter 2 inhibitor, tofogliflozin, in relation to sodium intake and glycaemic status

AIMS

Little is known about whether sodium intake is associated with the clinical effects of SGLT2 inhibitors (SGLT2is); however, SGLT2is may increase urinary sodium excretion. Thus, we investigated the impact of daily sodium intake on the estimated glomerular filtration rate (eGFR) via an SGLT2i, tofogliflozin (TOFO), in patients with type 2 diabetes (T2D).

METHODS

Individual-level data on 775 T2D patients in TOFO Phase 3 trials were analysed. Adjusted changes in variables during 52 weeks of TOFO therapy were compared according to basal daily salt intake (DSI), which was measured based on estimated daily urinary sodium excretion using the Tanaka formula. Multivariable analysis was used to investigate the impact of basal DSI on changes in eGFR at Weeks 4 and 52.

RESULTS

Sixty-six percent of participants were men; mean age, HbA1c, body mass index, eGFR_MDRD and median DSI were 58.5 years, 8.0%, 25.6 kg/m² , 83.9 mL/min/1.73 m² and 9.3 g/d, respectively. In all participants, eGFR_MDRD sharply dipped during Week 4, and gradually increased by Week 52, showing a significant increase overall from baseline to Week 52. Multivariable analysis showed that basal DSI and HbA1c levels were independently correlated with eGFR_MDRD changes at Weeks 4 and 52. Additionally, lower baseline HbA1c and DSI levels were significantly correlated with a greater increase in eGFR_MDRD at Week 52.

CONCLUSIONS

Dietary salt intake, in addition to glycaemic control, correlates with changed eGFR_MDRD via TOFO. Thus, an appropriate dietary approach to therapy should be considered before treatment of T2D patients with an SGLT2i.

Glucose fluctuation increased mesangial cell apoptosis related to AKT signal pathway

INTRODUCTION

Blood glucose fluctuation is an important factor for the development of diabetic complications. Glucose fluctuation aggravated the renal injury in diabetic nephropathy. In the present study, our aim was to investigate the effects of blood glucose fluctuation on the glomerular mesangal cells and its related mechanism.

MATERIAL AND METHODS

Mesangial cells were divided into four groups: the normal glucose group (NG) cells were incubated in normal glucose conditions (5.6 mmol/l); the high glucose group (HG) cells were treated with 25 mmol/l; the glucose fluctuation (FG) group received 5.6 mmol/l and 25 mmol/l glucose repeated 3 times; the mannitol group (MG) received 5.6 mmol/l glucose plus 24.4 mmol/l mannitol as a control. Cell viability and apoptosis were detected, reactive oxygen species (ROS) level, superoxide dismutase (SOD) activity and malonaldehyde (MDA) levels were measured. Phosphorylated ser/thr protein kinase (P-AKT, phosphor-Ser473), phosphorylated glycogen synthase kinase-3β (P-GSK-3β, phosphor-Ser9) and cleaved cysteinyl aspartate-specific proteinase-3 (cleaved caspase-3) levels were assessed using western blot.

RESULTS

Data suggested that mesangial cells in the FG group show higher cell viability in 12 h, and lower cell viability from 48 h. The FG group showed cell apoptosis accompanied by a significant MDA level increase and SOD activity decrease in 48 h. More importantly, glucose fluctuation could aggravate oxidative stress in glomerular mesangial cells. Furthermore, the P-AKT level was lower, and increased P-GSK-3β and cleaved caspase-3 levels were higher in the FG group than in the HG group.

CONCLUSIONS

Glucose fluctuation aggravates mesangial cell apoptosis, which may be partly induced by activating oxidative stress and inhibiting the AKT signaling pathway.

Heterogeneous Nuclear Ribonucleoprotein F Mediates Insulin Inhibition of Bcl2-Modifying Factor Expression and Tubulopathy in Diabetic Kidney

We investigated the molecular mechanism(s) by which insulin prevents Bcl2-modifying factor (Bmf)-induced renal proximal tubular cell (RPTC) apoptosis and loss in diabetic mice. Transgenic mice (Tg) mice specifically overexpressing human BMF in RPTCs and non-Tg littermates were studied at 10 to 20 weeks of age. Non-diabetic littermates, diabetic Akita mice +/− insulin implant, Akita Tg mice specifically overexpressing heterogeneous nuclear ribonucleoprotein F (hnRNP F) in their RPTCs and immortalized rat renal proximal tubular cells (IRPTCs) were also studied. BMF-Tg mice exhibited higher systolic blood pressure, urinary albumin/creatinine ratio, RPTC apoptosis and urinary RPTCs than non-Tg mice. Insulin treatment in Akita mice and Akita mice overexpressing hnRNP F suppressed Bmf expression and RPTC apoptosis. In hyperinsulinemic-euglycemic wild type mice, renal Bmf expression was down-regulated with up-regulation of hnRNP F. In vitro, insulin inhibited high glucose-stimulation of Bmf expression, predominantly via p44/42 mitogen-activated protein kinase (MAPK) signaling. Transfection of p44/42 MAPK or hnRNP F small interfering RNA (siRNA) prevented insulin inhibition of Bmf expression. HnRNP F inhibited Bmf transcription via hnRNP F-responsive element in the Bmf promoter. Our results demonstrate that hnRNP F suppression of Bmf transcription is an important mechanism by which insulin protects RPTCs from apoptosis in diabetes.

Renal Damaging Effect Elicited by Bicalutamide Therapy Uncovered Multiple Action Mechanisms As Evidenced by the Cell Model

Bicalutamide (Bic) is frequently used in androgen deprivation therapy (ADT) for treating prostate cancer. ADT-induced hypogonadism was reported to have the potential to lead to acute kidney injury (AKI). ADT was also shown to induce bladder fibrosis via induction of the transforming growth factor (TGF)-β level. We hypothesized that Bic can likely induce renal fibrosis. To understand this, a cell model was used to explore expressions of relevant profibrotic proteins. Results indicated that Bic initiated multiple apoptotic and fibrotic pathways, including androgen deprivation, downregulation of the androgen receptor → phosphatidylinositol-3-kinase → Akt pathway, upregulation of the extrinsic apoptotic pathway- tumor necrosis factor α →  nuclear factor κB → caspase-3, increased expressions of fibrosis-related proteins including platelet-derived growth factor β, fibronectin and collagen IV, and enhanced cell migration. The endoplasmic reticular stress pathway and smooth muscle actin were unaffected by Bic. Co-treatment with testosterone was shown to have an anti-apoptotic effect against Bic, suggesting a better outcome of Bic therapy if administered with an appropriate testosterone intervention. However, since Bic was found to inhibit the membrane transport and consumption rates of testosterone, a slightly larger dose of testosterone is recommended. In conclusion, these pathways can be considered to be pharmaceutically relevant targets for drug development in treating the adverse effects of Bic.

Gigantol has Protective Effects against High Glucose-Evoked Nephrotoxicity in Mouse Glomerulus Mesangial Cells by Suppressing ROS/MAPK/NF-κB Signaling Pathways

Gigantol is a bibenzyl compound derived from several medicinal orchids. This biologically active compound has shown promising therapeutic potential against diabetic cataracts, but whether this compound exerts beneficial effects on the other diabetic microvascular complications remains unclear. This study was carried out to examine effects of gigantol on high glucose-induced renal cell injury in cultured mouse kidney mesangial cells (MES-13). MES-13 cells were pretreated with gigantol (1, 5, 10 or 20 μmol/L) for 1 h followed by further exposure to high (33.3 mmol/L) glucose for 48 h. Gigantol concentration dependently enhanced cell viability followed by high glucose treatment in MES-13 cells. High glucose induced reactive oxygen species (ROS) generation, malondialdehyde production and glutathione deficiency were recoved in MES-13 cells pretreated with gigantol. High glucose triggered cell apoptosis via the the loss of mitochondrial membrane potential, depletion of adenosine triphosphate, upregulation of caspases 9 and 3, enhancement of cytochrome c release, and subsequent interruption of the Bax/Bcl-2 balance. These detrimental effects were ameliorated by gigantol. High glucose also induced activation of JNK, p38 mitogen-activated protein kinase (MAPK) and nuclear factor-κB (NF-κB) in MES-13 cells, which were blocked by gigantol. The results suggest that treatment MES-13 cells with gigantol halts high glucose-induced renal dysfunction through the suppression of the ROS/MAPK/NF-κB signaling pathways. Our data are of value to the understanding the mechanism for gigantol, and would benefit the study of drug development or food supplement for diabetes and nephropathy.

A Network Pharmacology Approach to Uncover the Mechanisms of Shen-Qi-Di-Huang Decoction against Diabetic Nephropathy

Shen-Qi-Di-Huang decoction (SQDHD), a well-known herbal formula from China, has been widely used in the treatment of diabetic nephropathy (DN). However, the pharmacological mechanisms of SQDHD have not been entirely elucidated. At first, we conducted a comprehensive literature search to identify the active constituents of SQDHD, determined their corresponding targets, and obtained known DN targets from several databases. A protein-protein interaction network was then built to explore the complex relations between SQDHD targets and those known to treat DN. Following the topological feature screening of each node in the network, 400 major targets of SQDHD were obtained. The pathway enrichment analysis results acquired from DAVID showed that the significant bioprocesses and pathways include oxidative stress, response to glucose, regulation of blood pressure, regulation of cell proliferation, cytokine-mediated signaling pathway, and the apoptotic signaling pathway. More interestingly, five key targets of SQDHD, named AKT1, AR, CTNNB1, EGFR, and ESR1, were significant in the regulation of the above bioprocesses and pathways. This study partially verified and predicted the pharmacological and molecular mechanisms of SQDHD on DN from a holistic perspective. This has laid the foundation for further experimental research and has expanded the rational application of SQDHD in clinical practice.

Angpt2 Induces Mesangial Cell Apoptosis through the MicroRNA-33-5p-SOCS5 Loop in Diabetic Nephropathy

Diabetic nephropathy (DN) is the leading cause of end-stage renal disease. Mesangial cell (MC) loss is correlated with worsening renal function in DN. Disturbance of angiopoietin (Angpt)/Tie ligand-receptor system causes inflammation and abnormal angiogenesis. This association between elevated circulating Angpt2 and poor renal outcome has been in DN patients. However, the pathogenic role of Angpt2 in the MCs remains unknown. We found serum Angpt2 levels were elevated in type 2 diabetes mellitus (DM) patients and db/db mice, which correlated with albuminuria. Angpt2 synergistically induced MC apoptosis under high glucose (HG), and miR-33-5p regulated Angpt2-inducing MC apoptosis treated with HG. Loss of miR-33-5p increased suppressor of cytokine signaling 5 (SOCS5), leading to the inhibition of Janus kinase 1 and signal transducer and activator of transcription 3 signaling transduction. Elevated expression of SOCS5 was found in the MCs in kidney sections of both db/db mice and type 2 DM patients. Decreased miR-33-5p levels were found in the urine of db/db mice and type 2 DM patients, and miR-33-55p levels negatively correlated with albuminuria. Angpt2 leads to MC apoptosis via the miR-33-5p-SOCS5 loop in DN. miR-33-5p is predictive of kidney injury in DN. These findings may provide future applications in predicting renal dysfunction and the therapeutic potential of DN.

Deletion of ApoM gene induces apoptosis in mouse kidney via mitochondrial and endoplasmic reticulum stress pathways

Apolipoprotein M (ApoM) is involved in lipid metabolism, and especially is involved in reverse cholesterol transport. However, the relationship between ApoM and apoptosis has been rarely reported. This study aimed to investigate the effect of ApoM on apoptosis using an ApoM gene-deficient mice (ApoM^-/-) model and a mouse mesangial cell model with suppressed ApoM gene expression. First, we observed by transmission electron microscopy that mitochondrial damage and endoplasmic reticulum stress were abnormally altered in the kidneys of ApoM^-/- mice compared with wild-type mice, showing mitochondrial swelling, vacuolization, myeloid changes, and expansion of the rough endoplasmic reticulum. At the molecular level, the expression of pro-apoptotic related proteins such as AIF, Bax, chop, clever-caspase 3, clever-caspase 7, clever-caspase 9, and clever-caspase 12 increased, and the expression of anti-apoptotic protein Bcl-2 decreased. Secondly, by interfering with the expression of the ApoM gene in mouse mesangial cells, we found that, compared with the control group (NC-si), the cells of the experimental group (siApoM) showed decreased cell viability, nuclear chromatin condensation, nuclear lysis, and an increased proportion of early apoptotic cells. The results in cells at the molecular level were consistent with those at the tissue level. These data indicated that the deletion of the ApoM gene led to upregulation of apoptosis in mouse kidney tissues and mesangial cells through the mitochondrial and endoplasmic reticulum pathways.

The mTOR promotes oxidative stress-induced apoptosis of mesangial cells in diabetic nephropathy

Glomerular mesangial cell (MC) apoptosis is one of the important mechanisms of glomerulosclerosis, which induces an increased severity of albuminuria and promotes the development of diabetic nephropathy (DN). However, the mechanism by which high glucose (HG) induces MCs apoptosis is not fully understood. In the present study, we investigated the effects of mTOR signalling on apoptosis in cultured MCs exposed to HG and in type I diabetes, and tried to clarify the specific mechanisms underlying these effects. In vitro, exposure of MCs to HG stimulated ROS production, decreased the antioxidant enzyme superoxide dismutase (SOD) activity and glutathione (GSH) level, increased nicotinamide adenine dinucleotide phosphate (NADPH) oxidase activity, upregulated P53 expression and Bax/Bcl-2 ratio and enhanced cleavage of caspase 3, resulting in an increase in programmed cell death. Pretreatment of the cells with rapamycin ameliorated oxidative stress, reduced the number of apoptotic cells induced by HG and caused the downstream effects of mTOR activation. In vivo, compared with control rats, diabetic rats had more apoptotic cells in glomeruli. Induction of diabetes increased the level of MDA and NADPH oxidase activity, decreased the SOD activity and GSH level, elevated the Bax/Bcl ratio and P53 expression and activated caspase 3. mTOR inhibitor rapamycin treatment prevented these changes further alleviated albuminuria and improved renal function. Taken together, our data suggest that mTOR plays a key role in mediating ROS-induced MC apoptosis in diabetic nephropathy, and these effects have been associated with the promotion of ROS production by upregulating the antioxidant enzyme and downregulating the NADPH oxidase activity.

Renal inhibition of miR-181a ameliorates 5-fluorouracil-induced mesangial cell apoptosis and nephrotoxicity

The development of nephrotoxicity largely limits the clinical use of chemotherapy. MiRNAs are able to target various genes and involved in the regulation of diverse cellular processes, including cell apoptosis and death. Our study showed that miR-181a expression was significantly increased after 5-fluorouracil (5-FU) treatment in renal mesangial cells and kidney tissue, which was associated with decreased baculoviral inhibition of apoptosis protein repeat-containing 6 (BIRC6) expression and increased apoptotic rate. Enforced miR-181a expression enhanced 5-FU-induced p53-dependent mitochondrial apoptosis, including declined Bcl-2/Bax ratio, loss of mitochondrial membrane potential, cytochrome c release, and caspase-9 and caspase-3 activation. However, inhibition of miR-181a was associated with reduced p53-mediated mitochondrial apoptosis induced by 5-FU. Moreover, miR-181a increased BIRC6 downstream gene p53 protein expression and transcriptional activity by reducing ubiquitin-mediated protein degradation. We found that miR-181a directly targeted 3'-UTR of BIRC6 mRNA and negatively regulated BIRC6 expression. In vivo study, knockdown of miR-181a with adeno-associated virus harboring miR-181a-tough decoy attenuated 5-FU-induced renal cell apoptosis, inflammation and kidney injury. In conclusion, these results demonstrate that miR-181a increases p53 protein expression and transcriptional activity by targeting BIRC6 and promotes 5-FU-induced apoptosis in mesangial cells. Inhibition of miR-181a ameliorates 5-FU-induced nephrotoxicity, suggesting that miR-181a may be a novel therapeutic target for nephrotoxicity treatment during chemotherapy.

RAGE Deletion Confers Renoprotection by Reducing Responsiveness to Transforming Growth Factor-β and Increasing Resistance to Apoptosis

Signaling via the receptor of advanced glycation end products (RAGE)-though complex and not fully elucidated in the setting of diabetes-is considered a key injurious pathway in the development of diabetic nephropathy (DN). We report here that RAGE deletion resulted in increased expression of fibrotic markers (collagen I and IV, fibronectin) and the inflammatory marker MCP-1 in primary mouse mesangial cells (MCs) and in kidney cortex. RNA sequencing analysis in MCs from RAGE^-/- and wild-type mice confirmed these observations. Nevertheless, despite these gene expression changes, decreased responsiveness to transforming growth factor-β was identified in RAGE^-/- mice. Furthermore, RAGE deletion conferred a more proliferative phenotype in MCs and reduced susceptibility to staurosporine-induced apoptosis. RAGE restoration experiments in RAGE^-/- MCs largely reversed these gene expression changes, resulting in reduced expression of fibrotic and inflammatory markers. This study highlights that protection against DN in RAGE knockout mice is likely to be due in part to the decreased responsiveness to growth factor stimulation and an antiapoptotic phenotype in MCs. Furthermore, it extends our understanding of the role of RAGE in the progression of DN, as RAGE seems to play a key role in modulating the sensitivity of the kidney to injurious stimuli such as prosclerotic cytokines.

Lycium chinense leaves extract ameliorates diabetic nephropathy by suppressing hyperglycemia mediated renal oxidative stress and inflammation

Diabetic nephropathy is one of the most serious and most frequently encountered diabetic complication, accounting for the highest cause of end-stage renal disease. This present study was aimed at exploring the protective/attenuative effect of Lycium chinense leaf extract (MELC) on streptozotocin induced diabetic nephropathy in experimental Sprague Dawley rats. The oral administration of diabetic rats with MELC markedly ameliorated renal dysfunction as observed in the significant reduction in the serum levels of creatinine, blood urea nitrogen (BUN), albumin and TGF-β1 as compared to the untreated diabetic control rats. In addition, the elevated levels of renal oxidative stress markers and pro-inflammatory parameters (GSH, SOD, CAT, MDA, TNF-α, IL-6 and IL-1β) were significantly reduced in MELC treated diabetic rats. The results obtained in this study suggests that L. chinense leaf might have the potential as possible pharmacological agent against diabetic nephropathy by suppressing renal oxidative stress and inflammation.

Anthocyanins inhibit high glucose-induced renal tubular cell apoptosis caused by oxidative stress in db/db mice

Oxidative stress is an important contributory factor resulting the development of kidney injury in patients with diabetes. Numerous in vitro and in vivo studies have suggested that anthocyanins, natural phenols commonly existing in numerous fruits and vegetables, exhibit important antioxidative, anti‑inflammatory and antihyperlipidemic effects; however, their effects and underlying mechanisms on diabetic nephropathy (DN) have not yet been fully determined. In the present study, the regulation of apoptosis metabolism and antioxidative effects exhibited by anthocyanins [grape seed procyanidin (GSPE) and cyanidin‑3‑O‑β‑glucoside chloride (C3G)] were investigated, and the molecular mechanism underlying this process was investigated in vivo and in vitro. GSPE administration was revealed to suppress renal cell apoptosis, as well as suppress the expression of Bcl‑2 in diabetic mouse kidneys. Furthermore, GSPE administration was demonstrated to suppress the expression of thioredoxin interacting protein (TXNIP), in addition to enhancing p38 mitogen‑activation protein kinase (MAPK) and extracellular signal‑regulated kinase 1/2 (ERK1/2) oxidase activity in diabetic mouse kidneys. In vitro experiments using HK‑2 cells revealed that C3G suppressed the generation of HG‑mediated reactive oxygen species, cellular apoptosis, the expression of cleaved caspase‑3 and the Bax/Bcl‑2 ratio; and enhanced the expression of cytochrome c released from mitochondria. Furthermore, treatment with C3G was revealed to suppress the expression of TXNIP, in addition to the phosphorylation of p38 MAPK and ERK1/2 oxidase activity in HK‑2 cells under HG conditions. In addition, treatment with C3G was revealed to attenuate the HG‑induced suppression of the biological activity of thioredoxin, and to enhance the expression of thioredoxin 2 in HK‑2 cells under HG conditions. In conclusion, the present study demonstrated that anthocyanins may exhibit protective effects against HG‑induced renal injury in DN via antioxidant activity.

P66Shc expression in diabetic rat retina

Background

P66Shc is partially localised within the mitochondrial fraction. It is primarily related to the generation of mitochondrial reactive oxygen species and apoptosis. Based on previous studies, we hypothesize that in the retina, p66Shc may exist and affect the development of diabetic retinopathy. The purpose of this study was to investigate p66Shc expression in retinal in streptozotocin-induced diabetic (SD) rats, which may provide a pathway to study the pathogenesis of diabetic retinopathy.

Methods

Reverse transcription-polymerase chain reaction (RT-PCR) and western blot were used to detect retinal p66Shc mRNA and protein expression in SD rats, respectively. Immunohistochemical staining was applied to detect the location of rat retinal p66Shc expression. TUNEL assay was applied to detect the number of apoptotic cells.

Results

P66Shc expression was found in the retina of normal and diabetic rats, and the level of mRNA and protein expression increased with the progression of diabetes mellitus (DM). P66Shc expression was mainly located in the retinal ganglion cell layer and inner nuclear layer. Compared with the normal group, retinal cell tissue apoptosis rate in the D12w group was significantly increased.

Conclusion

Rat retinal p66Shc expression was mainly in the ganglion cell layer and inner nuclear layer. As the degree of DM progressed, p66Shc expression gradually increased, and the number of apoptotic cells also increased.

Dynamic Changes of Secondary Metabolites and Antioxidant Activity of Ligustrum lucidum During Fruit Growth

There are a number of secondary metabolites having medicinal values in Ligustri Lucidi Fructus. In this study, the target analytes salidroside, ligustroflavone, specnuezhenide, oleuropein, oleanolic acid and ursolic acid were chosen, aiming to establish a method to investigate the content of six compounds during eight growth stages of Ligustri Lucidi Fructus. Even though the results indicated that the contents of six compounds in different growth periods reached their maximum value, they displayed a downward trend. The antioxidant activity of the analyzed samples also decreased along with the growth period. The relationship between the content of six secondary metabolites and the activity has been elucidated. Hence, this research provides a theoretical basis for guiding efficient use of Ligustri Lucidi Fructus.

Tear Levels of Insulin-Like Growth Factor Binding Protein 3 Correlate With Subbasal Nerve Plexus Changes in Patients With Type 2 Diabetes Mellitus

Purpose

This study investigated the expression of insulin-like growth factor binding protein-3 (IGFBP-3) in basal tears of patients with type 2 diabetes mellitus compared to nondiabetic controls; and correlated tear levels of IGFBP-3 with morphologic changes in the subbasal nerve plexus and density of basal corneal epithelial cells.

Methods

This was a single visit, cross-sectional study. Diabetic and control subjects were matched for age, sex, smoking status, and body mass index. Tear levels of IGFBP-3 were measured using ELISA. Corneal nerve and basal epithelial cell changes were measured using in vivo confocal microscopy.

Results

Tear levels of IGFBP-3 were 3.5-fold higher in those with diabetes. Patients with diabetes also showed a reduction in nerve fiber layer, nerve branch density, and corneal basal epithelial cell density. There was no significant difference in corneal sensitivity. IGFBP-3 levels were highly correlated with nerve fiber length and branch density; while hemoglobin (Hb)A1c was only moderately correlated. There were no significant differences in the clinical or subjective signs of dry eye between groups, indicating that tear levels of IGFBP-3 and corneal nerve changes were not due to the presence of mild dry eye.

Conclusions

These findings indicate that tear levels of IGFBP-3 are more tightly correlated to nerve fiber changes in diabetes than HbA1c. Future studies that stratify the severity of diabetic disease with tear levels of IGFBP-3 are needed to validate this finding.

Sitagliptin ameliorates high glucose-induced cell proliferation and expression of the extracellular matrix in glomerular mesangial cells

Diabetic nephropathy (DN) is one of the most important causes that leads to end-stage renal disease and the efficacy of strategies currently available for the prevention of DN remains unsatisfactory. Sitagliptin (SIT), which is a dipeptidyl peptidase-4 inhibitor, exhibited a modest beneficial effect on glycated hemoglobin levels and is capable of ameliorating renal ischemia reperfusion injury. By determining the expression of transforming growth factor-β1 (TGF-β1), connective tissue growth factor (CTGF), collagen type IV (ColIV) and fibronectin (FN) levels in high glucose-cultured glomerular mesangial cells (MCs), the present study aimed to assess the anti-proliferative and anti-fibrotic effects of SIT on the therapeutic potential for the prevention of DN and its mechanism. Specifically, cell proliferation was determined via cell counting kit-8 assay, and the expression levels of TGF-β1 and CTGF mRNA were detected by reverse transcription polymerase chain reaction analysis. Furthermore, the secretion of TGF-β1, CTGF, ColIV and FN proteins was measured via enzyme-linked immunosorbent assays. The results demonstrated that high glucose induced the proliferation of MCs and enhanced the expression of TGF-β1, CTGF, ColIV and FN. Furthermore, treatment with SIT inhibited cell proliferation and the expression of TGF-β1, CTGF, ColIV and FN induced by high glucose. In conclusion, SIT inhibits cell proliferation and the expression of the major extracellular matrix proteins induced by high glucose, indicating its value for treating or relieving DN.

Sodium-Glucose Cotransporter 2 Inhibitors with Renoprotective Effects

BACKGROUND

Diabetes is the leading cause of end-stage renal disease (ESRD) and accounts for 40-50% of patients requiring renal replacement therapy. The main pathophysiology of diabetic nephropathy comprises glucose-dependent pathways, hemodynamic pathways, and genetic factors.

SUMMARY

Glucose-dependent pathways, known as advanced glycation, polyols, and protein kinase C activation have been implicated in the pathogenesis of diabetic nephropathy. Current studies have indicated that intensified glycemic control retards the rate of development of albuminuria and impairs renal function in both patients with type 1 and 2 diabetes. However, therapeutic options have substantially increased over the last decade, but have not yet been translated to remarkably reduce the incidence of ESRD from diabetic nephropathy. Sodium-glucose cotransporter 2 (SGLT2) inhibitors are a novel class of glucose-lowering agents with potential renoprotective effects.

KEY MESSAGE

SGLT2 inhibitors represent a promising therapeutic approach to prevent and improve nephropathy among patients with type 2 diabetes. The current data strongly support that SGLT2 inhibitors have renoprotective properties not only by improving glycemic control but also through hemodynamic and nonhemodynamic renal effects. This review focuses on the latest published data dealing with hypoglycemic agents and SGLT2 inhibitors regarding the progression of kidney disease.

LY333531, a PKCβ inhibitor, attenuates glomerular endothelial cell apoptosis in the early stage of mouse diabetic nephropathy via down-regulating swiprosin-1

Glomerular endothelial cell (GEC) injury plays an important role in the early stage of diabetic nephropathy (DN). Previous studies show that a PKCβ inhibitor is effective for treating DN. In the current study we further explored the effects and molecular mechanisms of PKCβ inhibitors on GEC apoptosis in DN in streptozotocin-induced diabetic mice in vivo and high glucose- or PMA-treated human renal glomerular endothelial cells (HRGECs) in vitro. In the diabetic mice, hyperglycemia caused aggravated nephropathy and GEC apoptosis accompanied by significantly increased expression of swiprosin-1, a potentally pro-apoptotic protein. Administration of LY333531 (1 mg·kg^-1·d^-1 for 8 weeks) significantly attenuated both GEC apoptosis and swiprosin-1 upregulation in the diabetic mice. Similar results were observed in high glucose- or PMA-treated HRGECs in vitro. The pro-apoptotic role of swiprosin-1 was further examined using HRGECs treated with lentivirus mediating RNA interference or over-expression and swiprosin-1-knockout mice. Over-expression of swiprosin-1 in HRGECs resulted in increases in apoptosis and in caspase-9, caspase-3 and Bax expression. In contrast, knockdown of swiprosin-1 attenuated high glucose- or PMA-induced HRGECs apoptosis. Furthermore, over-expression of swiprosin-1 promoted interaction between swiprosin-1 and caspase-9 and increased the formation of apoptosomes. In diabetic swiprosin-1^-/- mice, the kidney/body weight, urinary albumin, glomerular hypertrophy, mitochondrial apoptotic-associated proteins and GEC apoptosis were significantly attenuated as compared with those in diabetic swiprosin-1^+/+ mice. These results demonstrate that swiprosin-1 is up-regulated by PKCβ in the early stage of DN, and that PKCβ facilitates GEC apoptosis through the mitochondrial-dependent pathway.

Attenuation of renal damage in type I diabetic rats by umbelliferone - a coumarin derivative

BACKGROUND

It is well known that diabetes is one of the non-communicable disease affecting a large population worldwide. When diabetes remains untreated or uncontrolled, it leads to further serious complications, affecting vital organs like eyes, kidney, heart, etc. The present study was designed to evaluate effects of umbelliferone, a phytochemical, in treatment of diabetic nephropathy.

METHODS

Experimental model used was streptozotocin (55mg/kg, ip) induced diabetic nephropathy in male Sprague Dawley rats. After 28days of streptozotocin administration, diabetic animals were treated with umbelliferone at two dose levels, 20 and 40mg/kg for next 28days.

RESULTS

The results of the study showed that umbelliferone treatment significantly decreased the elevated plasma creatinine and blood urea nitrogen level while significantly increased the total protein and albumin level in diabetic animals. Creatinine clearance was improved in umbelliferone treated animals. Renal oxidative stress was decreased in umbelliferone treated animals significantly. Histopathological study of the kidney was carried out by specific stains like Hematoxylin-Eosin, Periodic Acid Schiff and Masson Trichrome stain. The sections of the kidney showed that umbelliferone treatment decreased the glomerular damage, mesangial matrix expansion as well as the renal fibrosis. Determination of renal transforming growth factor beta one (TGF-β1) expression by immunohistochemical analysis, western blotting and circulating TGF-β1 by ELISA assay showed that umbelliferone decreased the renal tissue and circulating TGF-β1 level.

CONCLUSION

Umbelliferone treatment can significantly reduce the diabetes induced renal damage and can improve the pathological conditions related to the diabetic nephropathy by down regulation of TGF-β.

Apigenin ameliorates streptozotocin-induced diabetic nephropathy in rats via MAPK-NF-κB-TNF-α and TGF-β1-MAPK-fibronectin pathways

Diabetic nephropathy (DN), a microvascular complication of diabetes, has emerged as an important health problem worldwide. There is strong evidence to suggest that oxidative stress, inflammation, and fibrosis play a pivotal role in the progression of DN. Apigenin has been shown to possess antioxidant, anti-inflammatory, antiapoptotic, antifibrotic, as well as antidiabetic properties. Hence, we evaluated whether apigenin halts the development and progression of DN in streptozotocin (STZ)-induced diabetic rats. Male albino Wistar rats were divided into control, diabetic control, and apigenin treatment groups (5-20 mg/kg po, respectively), apigenin per se (20 mg/kg po), and ramipril treatment group (2 mg/kg po). A single injection of STZ (55 mg/kg ip) was administered to all of the groups except control and per se groups to induce type 1 diabetes mellitus. Rats with fasting blood glucose >250 mg/dl were included in the study and randomized to different groups. Thereafter, the protocol was continued for 8 mo in all of the groups. Apigenin (20 mg/kg) treatment attenuated renal dysfunction, oxidative stress, and fibrosis (decreased transforming growth factor-β1, fibronectin, and type IV collagen) in the diabetic rats. It also significantly prevented MAPK activation, which inhibited inflammation (reduced TNF-α, IL-6, and NF-κB expression) and apoptosis (increased expression of Bcl-2 and decreased Bax and caspase-3). Furthermore, histopathological examination demonstrated reduced inflammation, collagen deposition, and glomerulosclerosis in the renal tissue. In addition, all of these changes were comparable with those produced by ramipril. Hence, apigenin ameliorated renal damage due to DN by suppressing oxidative stress and fibrosis and by inhibiting MAPK pathway.

Zeaxanthin ameliorates high glucose-induced mesangial cell apoptosis through inhibiting oxidative stress via activating AKT signalling-pathway

Oxidative stress is a critical factor in the pathophysiology of diabetic kidney disease. Previous study shows that hyperglycaemia aggravates renal injury through oxidative stress in diabetic model, and antioxidants have beneficial effect on diabetic kidney disease. However, the role of antioxidants in the progression of diabetic kidney disease is poorly understood. The aim of this study was to clarify whether zeaxanthin, an antioxidant, could ameliorate mesangial cell injury and if so, identify the related mechanism underlying this protective effect. To that end, superoxide dismutase (SOD) activity and methane dicarboxylic aldehyde (MDA) levels were measured by an assay kit, and mesangial cell apoptosis and ROS levels were assessed using flow cytometry analysis. Furthermore, The levels of a phosphorylated ser/thr protein kinase (p-AKT), phosphorylated glycogen synthase kinase-3 beta (p-GSK-3β), Bcl-2 associated X protein (Bax) and cleaved cysteinyl aspartate-specific proteinase-3 (caspase-3) were detected by western blot. We found that zeaxanthin decreases MDA levels and increased SOD activity, as well as inhibits apoptosis and decreases ROS levels in mesangial cells in a high sugar environment. Furthermore, zeaxanthin increased p-AKT levels while decreased the levels of p-GSK-3β, Bax and cleaved-caspase-3. In addition, LY294002 reversed the protective effect of zeaxanthin on mesangial cells. In conclusion, zeaxanthin ameliorated mesangial cell apoptosis may be involved in inhibiting oxidative stress through activating of the AKT signalling pathway.

Novel insights into the pathophysiology and clinical aspects of diabetic nephropathy

Diabetic nephropathy (DN) is a well-described complication of diabetes mellitus and the leading cause of end stage renal disease (ESRD). Although increased albuminuria has been the gold standard for screening, data suggests that renal damage starts long before the onset of clinically apparent increases in macro and even micro-albuminuria. Clinical practice guidelines for the prevention of DN have been traditionally focused on the control of serum glucose, blood pressure and dyslipidemia, with some focus on the renin-angiotensin-aldosterone system (RAAS) as a main target for successful therapy. Recent evidence has led to a better understanding of the underlying mechanisms of the pathophysiology of this disease and suggests that various novels pathways can be targeted to delay and even prevent the progression of DN. Hence a more comprehensive therapeutic approach to therapy is on the horizon, carrying the promise for a more successful and impactful management. This review will highlight new insights into the pathophysiology, clinical aspects and future diagnostic and therapeutic modalities for DN.

Minocycline Attenuates Kidney Injury in a Rat Model of Streptozotocin-Induced Diabetic Nephropathy

The effects of minocycline on the development of diabetic nephropathy (DN) in streptozotocin (STZ) induced diabetic rats were evaluated in this study. The diabetes rats with DN were induced by STZ (55 mg/kg) injection. The experiment included 5 groups 1) normal, 2) normal plus minocycline for 16 weeks, 3) DN plus vehicle, 4) DN plus minocycline 16 weeks and 5) DN plus minocycline for 8 weeks. The pathological changes were analyzed by hematoxylin and eosin (H&E) staining and the apoptotic cells were stained by terminal deoxynucleotidyl transferase-mediated deoxyuridine triphosphate nick-end labeling (TUNEL) staining. The mRNA expression of caspase-3, Bax and Bcl-2 in the kidney tissues was detected by quantitative RT-PCR. The biochemical parameters of blood and urine were determined by biochemical analyzer. Treatment with minocycline reduced the urine volume, 24-h urine protein, serum creatinine (Scr), blood urea nitrogen (BUN) but not blood alanine aminotransferase (ALT) in the DN rats. Furthermore, treatment with minocycline improved the pathological score of STZ-injured kidney and reduced the numbers of apoptotic cells in the kidney of DN rats. Moreover, minocycline mitigated the expression of caspase-3 and Bax mRNA, but increased Bcl-2 expression in the kidney of DN rats. These data indicated that minocycline improved the STZ-induced kidney damages, at least partially by protection form long-term hyperglycemia-induced kidney cell apoptosis.

Protective mechanisms of melatonin against hydrogen-peroxide-induced toxicity in human bone-marrow-derived mesenchymal stem cells

Many obstacles compromise the efficacy of bone marrow mesenchymal stem cells (BM-MSCs) by inducing apoptosis in the grafted BM-MSCs. The current study investigates the effect of melatonin on important mediators involved in survival of BM-MSCs in hydrogen peroxide (H₂O₂) apoptosis model. In brief, BM-MSCs were isolated, treated with melatonin, and then exposed to H₂O₂. Their viability was assessed by MTT assay and apoptotic fractions were evaluated through Annexin V, Hoechst staining, and ADP/ATP ratio. Oxidative stress biomarkers including ROS, total antioxidant power (TAP), superoxide dismutase (SOD) and catalase (CAT) activity, glutathione (GSH), thiol molecules, and lipid peroxidation (LPO) levels were determined. Secretion of inflammatory cytokines (TNF-α and IL-6) were measured by ELISA assay. The protein expression of caspase-3, Bax, and Bcl-2, was also evaluated by Western blotting. Melatonin pretreatment significantly increased viability and decreased apoptotic fraction of H₂O₂-exposed BM-MSCs. Melatonin also decreased ROS generation, as well as increasing the activity of SOD and CAT enzymes and GSH content. Secretion of inflammatory cytokines in H₂O₂-exposed cells was also reduced by melatonin. Expression of caspase-3 and Bax proteins in H₂O₂-exposed cells was diminished by melatonin pretreatment. The findings suggest that melatonin may be an effective protective agent against H₂O₂-induced oxidative stress and apoptosis in MSC.

Inhibition of autophagy increased AGE/ROS-mediated apoptosis in mesangial cells

The aim of our study was to investigate the role of autophagy, a homeostatic process involved in the lysosomal degradation of damaged cell organelles and proteins, in regulating the survival of mesangial cells treated with advanced glycation end products (AGEs). In the present study, AGEs induced mitochondrial depolarization and led to mitochondrial-dependent apoptosis in mesangial cells, as shown by the loss of the mitochondrial membrane potential; increased Bax processing; increased Caspase-9, Caspase-3 and PARP cleavage; and decreased Bcl-2 expression. Meanwhile, AGEs also triggered autophagy flux in mesangial cells, as confirmed by the presence of autophagic vesicles, the conversion of LC3II/LC3I and the increase/decrease in Beclin-1/p62 expression. Interestingly, this study reported apparent apoptosis and autophagy that were dependent on reactive oxygen species (ROS) production. Scavenging ROS with N-acetyl-l-cysteine could prevent the appearance of the autophagic features and reverse AGE-induced apoptosis. Moreover, AGE-triggered mitophagy, which was confirmed by the colocalization of autophagosomes and mitochondria and Parkin translocation to mitochondria, played a potential role in reducing ROS production in mesangial cells. Additionally, inhibition of autophagy significantly enhanced AGE-induced cell apoptosis. Taken together, our data suggest that ROS were the mediators of AGE-induced mesangial cell apoptosis and that autophagy was likely to be the mechanism that was triggered to repair the ROS-induced damage in the AGE-treated cells and thereby promote cell survival. This study provides new insights into the molecular mechanism of autophagy involved in AGE-induced apoptosis in mesangial cells.