Resveratrol inhibits renal interstitial fibrosis in diabetic nephropathy by regulating AMPK/NOX4/ROS pathway

Circadian clock regulation of myofibroblast fate

Fibrosis-related disorders represent an increasing medical and economic burden on a worldwide scale, accounting for one-third of all disease-related deaths with limited therapeutic options. As central mediators in fibrosis development, myofibroblasts have been gaining increasing attention in the last 20 years as potential targets for fibrosis attenuation and reversal. While various aspects of myofibroblast physiology have been proposed as treatment targets, many of these approaches have shown limited long-term efficacy so far. However, ongoing research is uncovering new potential strategies for targeting myofibroblast activity, offering hope for more effective treatments in the future. The circadian molecular clock is a feature of almost every cell in the human body that dictates the rhythmic nature of various aspects of human physiology and behavior in response to changes in the surrounding environment. The dysregulation of these rhythms with aging is considered to be one of the underlying reasons behind the development of multiple aging-related chronic disorders, with fibrotic tissue scarring being a common pathological complication among the majority of them. Myofibroblast dysregulation due to skewed circadian clockwork might significantly contribute to fibrotic scar persistence. In the current review, we highlight the role of the circadian clock in the context of myofibroblast activation and deactivation and examine its dysregulation as a driver of fibrogenesis.

Verbascoside as a potential SGLT2 inhibitor in diabetic nephropathy: Targeting AMPK activation to suppress NOX4/NF-κB signaling and attenuate inflammation and fibrosis

Verbascoside, a caffeoyl phenylethanoid glycoside is known to regulate diabetic conditions and its related complications as well as function as an anti-infective, immunosuppressive, and antioxidant agent. It is also an under investigational molecule for patients of IgA Nephropathy. However, its functions in diabetic nephropathy (DN) and underlying mechanisms remain unclear. The study aimed to evaluate the therapeutic effects and mechanisms of verbascoside through the inhibition of sodium glucose transporter 2 (SGLT2) mediated glucose uptake in high glucose (HG) treated proximal tubular cells, HK-2 cells, and in silico studies. In HK-2 cells, verbascoside decreased glucose uptake analog, 6-NBDG through inhibition of SGLT2. The study demonstrated that HG could increase glucose uptake and induce renal inflammation and fibrosis by a significant increase in the intracellular levels of reactive oxygen species (ROS) derived from nicotinamide adenine dinucleotide phosphate oxidase-4 (NOX-4) in HK-2 cells. Nuclear factor kappa B (NF-κB) phosphorylation was also found to play a crucial role in HG-induced inflammation and fibrosis. Verbascoside exerted renoprotective effects by activating AMP-activated protein kinase (AMPK) and ameliorated renal dysfunction by suppressing pro-inflammatory factors, interleukin-6 (IL-6), and tumor necrosis factor-α (TNF-α), and expression of the extracellular matrix proteins, fibronectin (FN) and collagen-IV (COLIV) in HG-treated HK-2 cells. Molecular docking studies also revealed the SGLT2 inhibition properties of verbascoside. In summary, the study revealed that HG can directly promote glucose uptake through SGLT2 and renal complications and verbascoside is a potential therapeutic agent for ameliorating diabetic nephropathy via regulation of AMPK/NOX4/NF-κB signaling cascade.

Natural products in traditional Chinese medicine for renal fibrosis: a comprehensive review

Renal fibrosis represents the terminal pathological manifestation of most chronic kidney diseases, driving progressive loss of renal function. Natural products have emerged as promising therapeutic agents for preventing and ameliorating renal fibrosis due to their multi-target efficacy and favorable safety profiles. In this review, we conducted a comprehensive literature search on PubMed using the keywords "natural product" and "renal fibrosis" from 2004 to 2025, identifying 704 relevant articles. We systematically categorize and discuss the biological effects of key natural products and formulations with antifibrotic potential, focusing on five major classes: glycosides, flavonoids, phenolic compounds, anthraquinones, and terpenoids. Representative compounds from each category are highlighted for their mechanisms of action, including modulation of oxidative stress, inflammation, autophagy, and fibrosis signaling pathways. This review aims to provide a theoretical foundation for the development of natural product-based therapies to combat renal fibrosis, offering insights into their therapeutic potential and future research directions.

ERK1/2 gene expression and hypomethylation of Alu and LINE1 elements in patients with type 2 diabetes with and without cataract: Impact of hyperglycemia-induced oxidative stress

AIMS

This study aimed to delineate the effect of hyperglycemia on the Alu/LINE-1 hypomethylation and in ERK1/2 genes expression in type 2 diabetes with and without cataract.

METHODS

This study included 58 diabetic patients without cataracts, 50 diabetic patients with cataracts, and 36 healthy controls. After DNA extraction and bisulfite treatment, LINE-1 and Alu methylation levels were assessed using Real-time MSP. ERK1/2 gene expression was analyzed through real-time PCR. Total antioxidant capacity (TAC), and fasting plasma glucose (FPG) were measured using colorimetric methods. Statistical analysis was performed with SPSS23, setting the significance level at P < 0.05.

RESULTS

The TAC levels were significantly lower for cataract and diabetic groups than controls (259.31 ± 122.99, 312.43 ± 145.46, 372.58 ± 132.95 nanomole of Trolox equivalent) with a significant correlation between FPG and TAC levels in both the cataract and diabetic groups (P < 0.05). Alu and LINE-1 sequences were found to be statistically hypomethylated in diabetic and cataract patients compared to controls. In these groups, TAC levels were directly correlated with Alu methylation (P < 0.05) but not LINE-1. ERK1/2 gene expression was significantly higher in diabetic and cataract patients, showing increases of 2.41-fold and 1.43-fold for ERK1, and 1.27-fold and 1.5 for ERK2, respectively. ERK1 expression correlated significantly with FPG levels. A reverse correlation was observed between TAC levels and ERK1/2 expression.

CONCLUSIONS

Our findings indicate that hyperglycemia-induced oxidative stress may alter ERK1/2 gene expression patterns and induce aberrant hypomethylation in Alu and LINE-1 sequences. These aberrant changes may play a contributing role in diabetic complications such as cataracts.

Energy metabolism: An emerging therapeutic frontier in liver fibrosis

Liver fibrosis is a progressive response to chronic liver diseases characterized by a wound-healing process that leads to the accumulation of fibrillary extracellular matrix (ECM) proteins in and around the liver tissue. If left untreated, liver fibrosis can advance to cirrhosis and ultimately result in liver failure. Although there have been significant advancements in understanding the molecular mechanisms involved in liver fibrosis, effective therapeutic strategies to reverse or halt the condition remain limited. Recent research has underscored the critical role of energy metabolism in the initiation and progression of liver fibrosis. In response to liver injury, hepatic cells undergo metabolic reprogramming to meet the energy demands of myofibroblasts. This reprogramming involves various metabolic changes, including mitochondrial dysfunction, alterations in cellular bioenergetics, shifts in glycolysis and oxidative phosphorylation, as well as changes in lipid metabolism. These modifications can disrupt cellular energy homeostasis and increase energy release, activating hepatic cells, primarily hepatic stellate cells (HSCs). Activated HSCs then stimulate fibrogenic pathways, leading to the accumulation of ECM proteins in the liver, which exacerbates the progression of fibrosis. This review aims to explore the emerging connection between energy metabolism and liver fibrosis, focusing on the metabolic alterations and molecular mechanisms that drive this condition. We also examine the therapeutic implications of modulating energy metabolism to reduce energy release and mitigate liver fibrosis. Altering energy metabolism to decrease energy release may represent a promising approach for treating liver fibrosis and chronic liver diseases.

Therapeutic Effects of Liposomal Resveratrol in the Mitigation of Diabetic Nephropathy via Modulating Inflammatory Response, Oxidative Stress, and Apoptosis

An important factor in the development of diabetes and its associated consequences is prolonged chronic hyperglycemia, which weakens the antioxidant defense system and produces reactive oxygen species. Phytochemicals have been found to scavenge free radicals and exhibit antioxidant effects necessary to increase insulin sensitivity and reduce the development of diabetes-related complications. Current treatments for managing diabetes and diabetic nephropathy are often not very effective and come with several limitations and side effects. Resveratrol, for example, has shown therapeutic potential in mitigating kidney damage induced by high glucose levels, but its short bioavailability is a significant limitation. This accentuates the need for alternatives that not only improve the disease but also reduce the side effects associated with treatment. To enhance the therapeutic efficacy of resveratrol, we investigated the protective effects of liposomal resveratrol (LR) in a streptozotocin-induced diabetic rat model at doses of 20 and 40 mg/kg. We compared the impact of LR to that of resveratrol alone (at a dose of 40 mg/kg) on various parameters, including serum levels of biochemical markers, tissue levels of pro-inflammatory cytokines, nuclear transcription factor, oxidative stress indices, and apoptotic markers. LR, as a highly absorbable and metabolized form of resveratrol, has demonstrated beneficial effects in diabetic rats. Administered at both 20 mg/kg and 40 mg/kg dosages over a 5-week period, it demonstrated notable efficacy in alleviating inflammation. This was accomplished by diminishing the levels of pro-inflammatory mediators, TNF-α and IL-6, through the inhibition of NF-κB translocation. Additionally, LR influenced apoptotic markers, specifically caspase, BCL-2, and BAX. Furthermore, it enhanced the expression of key antioxidant enzymes such as catalase and glutathione peroxidase while significantly lowering malondialdehyde levels. These significant biochemical and immunological protective effects correlated with improved histological integrity and overall kidney architecture. Notably, resveratrol alone was not as effective as LR in restoring kidney function, highlighting its potential as a therapeutic candidate for the treatment of diabetic nephropathy. However, more in-depth studies are needed to explore its mechanism of action and improved bioavailability.

Beneficial effects of resveratrol on diabetes mellitus and its complications: focus on mechanisms of action

Diabetes mellitus (DM) is a significant global health issue, associated with various microvascular and macrovascular complications that significantly impair patients' quality of life as well as healthspan and lifespan. Despite the availability of several anti-diabetic medications with different mechanisms of action, there remains no definite curative treatment. Hence, discovering new efficient complementary therapies is essential. Natural products have received significant attention due to their advantages in various pathological conditions. Resveratrol is a natural polyphenol that possesses antioxidant and anti-inflammatory properties, and its efficacy has been previously investigated in several diseases, including DM. Herein, we aimed to provide a holistic view of the signaling pathways and mechanisms of action through which resveratrol exerts its effects against DM and its complications.

The protection of bisphenol A-modulated miRNAs and targets by natural products

Bisphenol A (BPA) is a ubiquitous environmental pollutant with endocrine-disrupting functions. Identifying protective drugs and exploring the mechanisms against BPA are crucial in healthcare. Natural products exhibiting antioxidant properties are considered to be able to protect against BPA toxicity. Although BPA-modulated targets and miRNAs have been individually reported, their connections to natural products were rarely organized. With the help of a protein-protein interaction database (STRING), the relationship between individual BPA-modulated targets was interconnected to provide a systemic view. In this review, BPA-downregulated and -upregulated targets are classified, and their interactive network was innovatively analyzed using the bioinformatic database (STRING). BPA-modulated miRNAs were also retrieved and ingeniously connected to BPA-modulated targets. Moreover, a novel connection between BPA-countering natural products was integrated into BPA-modulated miRNAs and targets. All these targets-associated natural products and/or miRNAs were incorporated into the STRING network, providing systemic relationships. Overall, the BPA-modulated target-miRNA-protecting natural product axis was innovatively constructed, providing a straightforward direction for exploring the integrated BPA-countering effects and mechanisms of natural products.

Hyaluronic acid-coated zein nanoparticle-mediated resveratrol therapy for the reduction of cisplatin-associated nephrotoxicity

Cisplatin (CDDP) is commonly used as an anticancer drug in clinical practice, but severe nephrotoxicity restricts it from exerting anticancer effects. Natural drugs, such as resveratrol, can alleviate the side effects of cisplatin, but their low solubility and gastrointestinal effects prevent them from working. Herein, we developed nanoparticles for kidney injury consisting of a biocompatible material, zein, as a carrier. HA-Zein/Res NPs were fabricated using low-molecular-weight hyaluronic acid coatings. This preparation is non-cytotoxic to renal tubular epithelial cells and can be used with confidence. Low-molecular-weight hyaluronic acid has inflammation-targeting properties and CDDP damage causes renal inflammation. Owing to this property of the low-molecular-weight hyaluronic acid coating, in vivo imaging experiments in mice demonstrated that the HA-Zein/Res NPs enabled more nanoparticles to accumulate in the renal sites affected by inflammation. Efficient resveratrol delivery alleviated kidney injury, and experiments demonstrated that HA-Zein/Res NPs could treat kidney injury while reducing the serum creatinine and urea nitrogen levels in mice. Collectively, these results indicated that this nanomaterial is a promising agent for reducing the clinical nephrotoxicity of cisplatin.

Role of oxidative stress in diabetes-induced complications and their management with antioxidants

Diabetes mellitus (DM) is a huge global health issue and one of the most studied diseases, with a large global prevalence. Oxidative stress is a cytotoxic consequence of the excessive development of ROS and suppression of the antioxidant defense system for ROS elimination, which accelerates the progression of diabetes complications such as diabetic neuropathy, retinopathy, and nephropathy. Hyperglycaemia induced oxidative stress causes the activation of seven major pathways implicated in the pathogenesis of diabetic complications. These pathways increase the production of ROS and RNS, which contributes to dysregulated autophagy, gene expression changes, and the development of numerous pro-inflammatory mediators which may eventually lead to diabetic complications. This review will illustrate that oxidative stress plays a vital role in the pathogenesis of diabetic complications, and the use of antioxidants will help to reduce oxidative stress and thus may alleviate diabetic complications.

The pivotal role of glucose transporter 1 in diabetic kidney disease

Diabetes mellitus (DM) is a significant public health problem. Diabetic kidney disease (DKD) is the most common complication of DM, and its incidence has been increasing with the increasing prevalence of DM. Given the association between DKD and mortality in patients with DM, DKD is a significant burden on public health resources. Despite its significance in DM progression, the pathogenesis of DKD remains unclear. Aberrant glucose uptake by cells is an important pathophysiological mechanism underlying DKD renal injury. Glucose is transported across the bilayer cell membrane by a glucose transporter (GLUT) located on the cell membrane. Multiple GLUT proteins have been identified in the kidney, and GLUT1 is one of the most abundantly expressed isoforms. GLUT1 is a crucial regulator of intracellular glucose metabolism and plays a key pathological role in the phenotypic changes in DKD mesangial cells. In an attempt to understand the pathogenesis of DKD better, we here present a review of studies on the role of GLUT1 in the development and progression of DKD.

Resveratrol delays the progression of diabetic nephropathy through multiple pathways: A dose-response meta-analysis based on animal models

OBJECTIVE

Accumulating experimental evidence has shown that resveratrol supplementation is effective for treating diabetic nephropathy (DN) in animal models. In this systematic review and meta-analysis, we assessed the effects and multiple mechanisms of resveratrol in animal models of DN.

METHODS

Before September 2023, preclinical literature was systematically searched and screened across PubMed, Web of Science, EMBASE, and the Cochrane Library. Forty-two studies were included, and the risk of bias tool from SYRCLE was used to assess the methodological quality. Pooled overall effect sizes of the results were generated by STATA 16.0.

RESULTS

The overall results provide preliminary evidence that the consumption of resveratrol can significantly reduce the mesangial index, glomerular basement membrane thickness, glomerular hypertrophy, serum creatinine, blood urea nitrogen, 24-h urinary protein, blood glucose, kidney index, total cholesterol, triglyceride, and low-density lipoprotein cholesterol levels. In contrast, the levels of albumin and high-density lipoprotein cholesterol are significantly increased. However, resveratrol did not significantly reduce creatinine clearance or glycated hemoglobin levels. Dose-response analysis revealed that resveratrol was most effective at improving kidney function and reducing DN when administered at lower doses of ≤15 mg/kg/day or higher doses of 100-200 mg/kg/day, with significant improvements in biochemical kidney injury markers and a better effect on dysglycemia.

CONCLUSIONS

The benefits of resveratrol in DN are likely due to its anti-inflammatory, antioxidant, metabolic regulatory, and autophagy-promoting effects. To confirm these findings for clinical use, further large-scale, long-term, high-quality preclinical trials are warranted to accurately assess the anti-DN effects and safety of resveratrol.

Taraxerone exerts antipulmonary fibrosis effect through Smad signaling pathway and antioxidant stress response in a Sirtuin1-dependent manner

Idiopathic pulmonary fibrosis treatments are limited, often with severe side effects, highlighting the need for novel options. Taraxerone has diverse biomedical properties, but its mechanism remains unclear. This study investigates taraxerone's impact and the mechanisms involved in bleomycin-induced pulmonary fibrosis in mice. After establishing a pulmonary fibrosis mouse model, taraxerone was intraperitoneally injected continuously for 14-28 days. The in vivo antifibrotic and antioxidative stress effects of taraxerone were assessed. In vitro, the influence of taraxerone on transforming growth factor-β1-induced myofibroblast transformation and oxidative stress was investigated. Subsequently, quantitative polymerase chain reaction screened the histone deacetylase and Sirtuin family, and taraxerone's effects on SIRT1 were assessed. After SIRT1 siRNA treatment, changes in myofibroblast transformation and antioxidant capacity in response to taraxerone were observed. Acetylation and phosphorylation levels of Smad3 were evaluated. We also examined the binding levels of SIRT1 with Pho-Smad3 and Smad3, as well as the nuclear localization of Smad2/3. EX527 confirmed SIRT1's in vivo action in response to taraxerone. In vitro experiments suggested that taraxerone inhibited myofibroblast differentiation by activating SIRT1 and reducing oxidative stress. We also observed a new interaction between SIRT1 and the Smad complex. Taraxerone activates SIRT1, enabling it to bind directly to Smad3. This leads to reduced Smad complex phosphorylation and limited nuclear translocation. As a result, the transcription of fibrotic factors is reduced. In vivo validation confirms taraxerone's SIRT1-mediated antifibrotic effectiveness. This suggests that targeting SIRT1-mediated inhibition of myofibroblast differentiation could be a key strategy in taraxerone-based therapy for pulmonary fibrosis.

Research progress of SIRTs activator resveratrol and its derivatives in autoimmune diseases

Autoimmune diseases (AID) have emerged as prominent contributors to disability and mortality worldwide, characterized by intricate pathogenic mechanisms involving genetic, environmental, and autoimmune factors. In response to this challenge, a growing body of research in recent years has delved into genetic modifications, yielding valuable insights into AID prevention and treatment. Sirtuins (SIRTs) constitute a class of NAD-dependent histone deacetylases that orchestrate deacetylation processes, wielding significant regulatory influence over cellular metabolism, oxidative stress, immune response, apoptosis, and aging through epigenetic modifications. Resveratrol, the pioneering activator of the SIRTs family, and its derivatives have captured global scholarly interest. In the context of AID, these compounds hold promise for therapeutic intervention by modulating the SIRTs pathway, impacting immune cell functionality, suppressing the release of inflammatory mediators, and mitigating tissue damage. This review endeavors to explore the potential of resveratrol and its derivatives in AID treatment, elucidating their mechanisms of action and providing a comprehensive analysis of current research advancements and obstacles. Through a thorough examination of existing literature, our objective is to advocate for the utilization of resveratrol and its derivatives in AID treatment while offering crucial insights for the formulation of innovative therapeutic approaches.

Nutritional Strategies against Diabetic Nephropathy: Insights from Animal Studies and Human Trials

Diabetic nephropathy (DN), defined as continuously elevated urinary albumin and a diminished estimated glomerular filtration rate, is a serious complication of both type 1 diabetes and type 2 diabetes and is the main cause of end-stage kidney disease. Patients with end-stage renal disease require chronic kidney dialysis and/or a kidney transplantation. Research highlights the role of diet in modulating specific signaling pathways that are instrumental in the progression of DN. Nutrient-sensitive pathways, affected by nutritional compounds and dietary components, offer a novel perspective on the management of DN by influencing inflammation, oxidative stress, and nutrient metabolism. Animal models have identified signaling pathways related to glucose metabolism, inflammation responses, autophagy, and lipid metabolism, while human population studies have contributed to the clinical significance of designing medical and nutritional therapies to attenuate DN progression. Here, we will update recent progress in research into the renoprotective or therapeutic effects of nutritional compounds, and potential nutrition-modulated pathways.

Using the concept of food as medicine to mitigate inflammation in patients undergoing peritoneal dialysis

The most common kidney replacement therapy (KRT) worldwide is hemodialysis (HD), and only 5%-10% of patients are prescribed peritoneal dialysis (PD) as KRT. Despite PD being a different method, these patients also present particular complications, such as oxidative stress, gut dysbiosis, premature aging, and mitochondrial dysfunction, leading to an inflammation process and high cardiovascular mortality risk. Although recent studies have reported nutritional strategies in patients undergoing HD with attempts to mitigate these complications, more information must be needed for PD patients. Therefore, this review provides a comprehensive analysis of recent studies of nutritional intervention to mitigate inflammation in PD patients.

The role of mitochondrial dysfunction in kidney injury and disease

Mitochondria are the main sites of aerobic respiration in the cell and mainly provide energy for the organism, and play key roles in adenosine triphosphate (ATP) synthesis, metabolic regulation, and cell differentiation and death. Mitochondrial dysfunction has been identified as a contributing factor to a variety of diseases. The kidney is rich in mitochondria to meet energy needs, and stable mitochondrial structure and function are essential for normal kidney function. Recently, many studies have shown a link between mitochondrial dysfunction and kidney disease, maintaining mitochondrial homeostasis has become an important target for kidney therapy. In this review, we integrate the role of mitochondrial dysfunction in different kidney diseases, and specifically elaborate the mechanism of mitochondrial reactive oxygen species (mtROS), autophagy and ferroptosis involved in the occurrence and development of kidney diseases, providing insights for improved treatment of kidney diseases.

Potential role of resveratrol in prevention and therapy of diabetic complications: a critical review

BACKGROUND

Diabetes mellitus (DM) is a category of metabolic conditions affecting about 5% of people worldwide. High mortality associated with DM is mostly due to its severe clinical complications, including diabetic nephropathy, retinopathy, neuropathy, and cardiomyopathy. Resveratrol (RSV) is a natural, biologically active polyphenol known to have various health-promoting effects in animal models and humans.

OBJECTIVE

In this review, we have reviewed the preventive and therapeutic role of RSV on diabetes complications with emphasis on its molecular mechanisms of action.

METHODS

To prepare this review, all the basic and clinical available literatures regarding this topic were gathered through electronic databases, including PubMed, Web of Science, Scopus, and Google Scholar. Therefore, we summarized previous studies that have evaluated the effects of RSV on diabetic complications and their mechanisms. Only English language studies published up to January 2023 were included in this review.

RESULTS

RSV improves glucose homeostasis, decreases insulin resistance, induces autophagy, regulates lipid metabolism, protects pancreatic β-cells, ameliorates metabolic disorders, and increases the GLUT4 expression. These effects induced by RSV are strongly associated with ability of this polyphenol agent to elevation expression/activity of AMP-activated protein kinase and Sirtuin 1 in various organs of diabetic subjects, which leads to prevention and therapy of diabetic complications. In addition, antioxidant and anti-inflammatory properties of RSV were reported to be involved in its action in diabetic complications, such as retinopathy and nephropathy.

CONCLUSION

RSV is a promising compound for improving diabetic complications. However, the exact antidiabetic mechanisms of RSV need to be further investigated.

Natural products in traditional Chinese medicine: molecular mechanisms and therapeutic targets of renal fibrosis and state-of-the-art drug delivery systems

Renal fibrosis (RF) is the end stage of several chronic kidney diseases. Its series of changes include excessive accumulation of extracellular matrix, epithelial-mesenchymal transition (EMT) of renal tubular cells, fibroblast activation, immune cell infiltration, and renal cell apoptosis. RF can eventually lead to renal dysfunction or even renal failure. A large body of evidence suggests that natural products in traditional Chinese medicine (TCM) have great potential for treating RF. In this article, we first describe the recent advances in RF treatment by several natural products and clarify their mechanisms of action. They can ameliorate the RF disease phenotype, which includes apoptosis, endoplasmic reticulum stress, and EMT, by affecting relevant signaling pathways and molecular targets, thereby delaying or reversing fibrosis. We also present the roles of nanodrug delivery systems, which have been explored to address the drawback of low oral bioavailability of natural products. This may provide new ideas for using natural products for RF treatment. Finally, we provide new insights into the clinical prospects of herbal natural products.

Oxidative stress and inflammation in diabetic nephropathy: role of polyphenols

Diabetic nephropathy (DN) often leads to end-stage renal disease. Oxidative stress demonstrates a crucial act in the onset and progression of DN, which triggers various pathological processes while promoting the activation of inflammation and forming a vicious oxidative stress-inflammation cycle that induces podocyte injury, extracellular matrix accumulation, glomerulosclerosis, epithelial-mesenchymal transition, renal tubular atrophy, and proteinuria. Conventional treatments for DN have limited efficacy. Polyphenols, as antioxidants, are widely used in DN with multiple targets and fewer adverse effects. This review reveals the oxidative stress and oxidative stress-associated inflammation in DN that led to pathological damage to renal cells, including podocytes, endothelial cells, mesangial cells, and renal tubular epithelial cells. It demonstrates the potent antioxidant and anti-inflammatory properties by targeting Nrf2, SIRT1, HMGB1, NF-κB, and NLRP3 of polyphenols, including quercetin, resveratrol, curcumin, and phenolic acid. However, there remains a long way to a comprehensive understanding of molecular mechanisms and applications for the clinical therapy of polyphenols.

Nox4 as a novel therapeutic target for diabetic vascular complications

Diabetic vascular complications can affect both microvascular and macrovascular. Diabetic microvascular complications, such as diabetic nephropathy, diabetic retinopathy, diabetic neuropathy, and diabetic cardiomyopathy, are believed to be caused by oxidative stress. The Nox family of NADPH oxidases is a significant source of reactive oxygen species and plays a crucial role in regulating redox signaling, particularly in response to high glucose and diabetes mellitus. This review aims to provide an overview of the current knowledge about the role of Nox4 and its regulatory mechanisms in diabetic microangiopathies. Especially, the latest novel advances in the upregulation of Nox4 that aggravate various cell types within diabetic kidney disease will be highlighted. Interestingly, this review also presents the mechanisms by which Nox4 regulates diabetic microangiopathy from novel perspectives such as epigenetics. Besides, we emphasize Nox4 as a therapeutic target for treating microvascular complications of diabetes and summarize drugs, inhibitors, and dietary components targeting Nox4 as important therapeutic measures in preventing and treating diabetic microangiopathy. Additionally, this review also sums up the evidence related to Nox4 and diabetic macroangiopathy.

ROS promote hyper-methylation of NDRG2 promoters in a DNMTS-dependent manner: Contributes to the progression of renal fibrosis

Renal fibrosis is the common histopathological feature of chronic kidney diseases (CKD), and there is increasing evidence that epigenetic regulation is involved in the occurrence and progression of renal fibrosis. N-myc downstream-regulated gene 2 (NDRG2) is significantly down-regulated in renal fibrosis, the mechanism of which remains unclear. Previous studies have confirmed that the inhibition of NDRG2 expression in tumor cells is related to hyper-methylation, mainly regulated by DNA methyltransferases (DNMTS). Herein, we explored the expression of NDRG2 and its epigenetic regulatory mechanism in renal fibrosis. The results showed that the expression of NDRG2 was significantly inhibited in vivo and in vitro, while the overexpression of NDRG2 effectively alleviated renal fibrosis. Meanwhile, we found that the expression of DNMT1/3A/3B was significantly increased in hypoxia-induced HK2 cells and Unilateral Ureteral Obstruction (UUO) mice accompanied by hyper-methylation of the NDGR2 promoter. Methyltransferase inhibitor (5-AZA-dC) corrected the abnormal expression of DNMT1/3A/3B, reduced the methylation level of NDRG2 promoter and restored the expression of NDRG2. The upstream events that mediate changes in NDRG2 methylation were further explored. Reactive oxygen species (ROS) are important epigenetic regulators and have been shown to play a key role in renal injury due to various causes. Accordingly, we further explored whether ROS could induce DNA-epigenetic changes of the expression of NDRG2 and then participated in the development of renal fibrosis. Our results showed that mitochondria-targeted antioxidants (Mito-TEMPO) could reverse the epigenetic inhibition of NDRG2 in a DNMT-sensitive manner, showing strong ability of DNA demethylation, exhibiting epigenetic regulation and anti-fibrosis effects similar to 5-AZA-dC. More importantly, the anti-fibrotic effects of 5-AZA-dC and Mito-TEMPO were eliminated in HK2 cells with NDRG2 knockdown. These findings highlight that targeting ROS-mediated hyper-methylation of NDRG2 promoter is a potentially effective therapeutic strategy for renal fibrosis, which will provide new insights into the treatment of CKD.

Diosgenin Inhibits ROS Generation by Modulating NOX4 and Mitochondrial Respiratory Chain and Suppresses Apoptosis in Diabetic Nephropathy

Diosgenin (DIO) is a dietary steroid sapogenin possessing multiple biological functions, such as the amelioration of diabetes. However, the remission effect of DIO on diabetic nephropathy (DN) underlying oxidative stress and cell apoptosis remains unclear. Here, the effect of DIO on ROS generation and its induced cell apoptosis was studied in vitro and in vivo. Renal proximal tubular epithelial (HK-2) cells were treated with DIO (1, 2, 4 µM) under high glucose (HG, 30 mM) conditions. DN rats were induced by a high-fat diet combined with streptozotocin, followed by administration of DIO for 8 weeks. Our data suggested that DIO relieved the decline of HK-2 cell viability and renal pathological damage in DN rats. DIO also relieved ROS (O2- and H2O2) production. Mechanistically, DIO inhibited the expression of NOX4 and restored mitochondrial respiratory chain (MRC) complex I-V expressions. Further, DIO inhibited mitochondrial apoptosis by ameliorating mitochondrial membrane potential (MtMP) and down-regulating the expressions of CytC, Apaf-1, caspase 3, and caspase 9, while up-regulating Bcl2 expression. Moreover, the ER stress and its associated cell apoptosis were inhibited through decreasing PERK, p-PERK, ATF4, IRE1, p-CHOP, and caspase 12 expressions. Collectively, DIO inhibited ROS production by modulating NOX4 and MRC complexes, which then suppressed apoptosis regulated by mitochondria and ER stress, thereby attenuating DN.

Single Nucleotide Polymorphisms of the RAC1 Gene as Novel Susceptibility Markers for Neuropathy and Microvascular Complications in Type 2 Diabetes

Single nucleotide polymorphisms (SNP) in the RAC1 (Rac family small GTPase 1) gene have recently been linked to type 2 diabetes (T2D) and hyperglycemia due to their contribution to impaired redox homeostasis. The present study was designed to determine whether the common SNPs of the RAC1 gene are associated with diabetic complications such as neuropathy (DN), retinopathy (DR), nephropathy, angiopathy of the lower extremities (DA), and diabetic foot syndrome. A total of 1470 DNA samples from T2D patients were genotyped for six common SNPs by the MassArray Analyzer-4 system. The genotype rs7784465-T/C of RAC1 was associated with an increased risk of DR (p = 0.016) and DA (p = 0.03) in males, as well as with DR in females (p = 0.01). Furthermore, the SNP rs836478 showed an association with DR (p = 0.005) and DN (p = 0.025) in males, whereas the SNP rs10238136 was associated with DA in females (p = 0.002). In total, three RAC1 haplotypes showed significant associations (FDR < 0.05) with T2D complications in a sex-specific manner. The study's findings demonstrate, for the first time, that the RAC1 gene's polymorphisms represent novel and sex-specific markers of neuropathy and microvascular complications in type 2 diabetes, and that the gene could be a new target for the pharmacological inhibition of oxidative stress as a means of preventing diabetic complications.

Application and Study of ROCK Inhibitors in Pulmonary Fibrosis: Recent Developments and Future Perspectives

Rho-associated coiled-coil-containing kinases (ROCKs), serine/threonine protein kinases, were initially identified as downstream targets of the small GTP-binding protein Rho. Pulmonary fibrosis (PF) is a lethal disease with limited therapeutic options and a particularly poor prognosis. Interestingly, ROCK activation has been demonstrated in PF patients and in animal PF models, making it a promising target for PF treatment. Many ROCK inhibitors have been discovered, and four of these have been approved for clinical use; however, no ROCK inhibitors are approved for the treatment of PF patients. In this article, we describe ROCK signaling pathways and the structure-activity relationship, potency, selectivity, binding modes, pharmacokinetics (PKs), biological functions, and recently reported inhibitors of ROCKs in the context of PF. We will also focus our attention on the challenges to be addressed when targeting ROCKs and discuss the strategy of ROCK inhibitor use in the treatment of PF.

Imidazo[1,2-a]pyridine Derivatives as AMPK Activators: Synthesis, Structure-Activity Relationships, and Regulation of Reactive Oxygen Species in Renal Fibroblasts

Adenosine 5'-monophosphate activated protein kinase (AMPK) has emerged as a promising target for the discovery of drugs to treat diabetic nephropathy (DN). Herein, a series of imidazo[1,2-a]pyridines were designed and synthesized. Among them, the active compound (EC₅₀ =11.0 nM) showed good enzyme activation and molecular docking results showed hydrogen bonding interactions with the key amino acids Asn111 and Lys29 in the active site. Meanwhile, further cellular level experiments revealed that it could reduce reactive oxygen species (ROS) levels in NRK-49F cells induced by high glucose, and Western Blot experiments also demonstrate that it can increase the levels of p-AMPK and p-ACC and decrease the levels of TGF-β1. The results of this study extend the structural types of AMPK activators and provide novel lead compounds for the subsequent development.

Sestrin2 Signaling Pathway Regulates Podocyte Biology and Protects against Diabetic Nephropathy

Sestrin2 regulates cell homeostasis and is an upstream signaling molecule for several signaling pathways. Sestrin2 leads to AMP-activated protein kinase- (AMPK-) and GTPase-activating protein activity toward Rags (GATOR) 1-mediated inhibition of mammalian target of rapamycin complex 1 (mTORC1), thereby enhancing autophagy. Sestrin2 also improves mitochondrial biogenesis via AMPK/Sirt1/peroxisome proliferator-activated receptor-gamma coactivator 1 alpha (PGC-1α) signaling pathway. Blockade of ribosomal protein synthesis and augmentation of autophagy by Sestrin2 can prevent misfolded protein accumulation and attenuate endoplasmic reticulum (ER) stress. In addition, Sestrin2 enhances P62-mediated autophagic degradation of Keap1 to release nuclear factor erythroid 2-related factor 2 (Nrf2). Nrf2 release by Sestrin2 vigorously potentiates antioxidant defense in diabetic nephropathy. Impaired autophagy and mitochondrial biogenesis, severe oxidative stress, and ER stress are all deeply involved in the development and progression of diabetic nephropathy. It has been shown that Sestrin2 expression is lower in the kidney of animals and patients with diabetic nephropathy. Sestrin2 knockdown aggravated diabetic nephropathy in animal models. In contrast, upregulation of Sestrin2 enhanced autophagy, mitophagy, and mitochondrial biogenesis and suppressed oxidative stress, ER stress, and apoptosis in diabetic nephropathy. Consistently, overexpression of Sestrin2 ameliorated podocyte injury, mesangial proliferation, proteinuria, and renal fibrosis in animal models of diabetic nephropathy. By suppressing transforming growth factor beta (TGF-β)/Smad and Yes-associated protein (YAP)/transcription enhancer factor 1 (TEF1) signaling pathways in experimental models, Sestrin2 hindered epithelial-mesenchymal transition and extracellular matrix accumulation in diabetic kidneys. Moreover, modulation of the downstream molecules of Sestrin2, for instance, augmentation of AMPK or Nrf2 signaling and inhibition of mTORC1, has been protective in diabetic nephropathy. Regarding the beneficial effects of Sestrin2 on diabetic nephropathy and its interaction with several signaling molecules, it is worth targeting Sestrin2 in diabetic nephropathy.

Obligatory Role of AMPK Activation and Antioxidant Defense Pathway in the Regulatory Effects of Metformin on Cellular Protection and Prevention of Lens Opacity

Increasing levels of oxidative-stress due to deterioration of the Nrf2 (NFE2-related factor)/ARE (antioxidant response element) pathway is found to be a primary cause of aging pathobiology. Metformin having anti-aging effects can delay/halt aging-related diseases. Herein, using lens epithelial cell lines (LECs) of human (h) or mouse (m) and aging h/m primary LECs along with lenses as model systems, we demonstrated that Metformin could correct deteriorated Bmal1/Nrf2/ARE pathway by reviving AMPK-activation, and transcriptional activities of Bmal1/Nrf2, resulting in increased antioxidants enzymatic activity and expression of Phase II enzymes. This ensued reactive oxygen species (ROS) mitigation with cytoprotection and prevention of lens opacity in response to aging/oxidative stress. It was intriguing to observe that Metformin internalized lens/LECs and upregulated OCTs (Organic Cation Transporters). Mechanistically, we found that Metformin evoked AMPK activation-dependent increase of Bmal1, Nrf2, and antioxidants transcription by promoting direct E-Box and ARE binding of Bmal1 and Nrf2 to the promoters. Loss-of-function and disruption of E-Box/ARE identified that Metformin acted by increasing Bmal1/Nrf2-mediated antioxidant expression. Data showed that AMPK-activation was a requisite for Bmal1/Nrf2-antioxidants-mediated defense, as pharmacologically inactivating AMPK impeded the Metformin's effect. Collectively, the results for the first-time shed light on the hitherto incompletely uncovered crosstalk between the AMPK and Bmal1/Nrf2/antioxidants mediated by Metformin for blunting oxidative/aging-linked pathobiology.

The interaction between cellular senescence and chronic kidney disease as a therapeutic opportunity

Chronic kidney disease (CKD) is an increasingly serious public health problem in the world, but the effective therapeutic approach is quite limited at present. Cellular senescence is characterized by the irreversible cell cycle arrest, senescence-associated secretory phenotype (SASP) and senescent cell anti-apoptotic pathways (SCAPs). Renal senescence shares many similarities with CKD, including etiology, mechanism, pathological change, phenotype and outcome, however, it is difficult to judge whether renal senescence is a trigger or a consequence of CKD, since there is a complex correlation between them. A variety of cellular signaling mechanisms are involved in their interactive association, which provides new potential targets for the intervention of CKD, and then extends the researches on senotherapy. Our review summarizes the common features of renal senescence and CKD, the interaction between them, the strategies of senotherapy, and the open questions for future research.

Astragaloside IV Alleviates Renal Tubular Epithelial-Mesenchymal Transition via CX3CL1-RAF/MEK/ERK Signaling Pathway in Diabetic Kidney Disease

Background

Epithelial–mesenchymal transition (EMT) plays an important role in interstitial matrix deposition and renal fibrosis in diabetic kidney disease (DKD). It has been verified that Astragaloside IV (AS-IV) is beneficial for ameliorating DKD. However, the underlying mechanisms of AS-IV on regulating EMT in DKD are yet to be established. Accumulated evidence has suggested that C-X3-C motif ligand 1 (CX3CL1) plays a significant role in the progression of EMT.

Purpose

We aimed to investigate whether AS-IV could alleviate EMT by regulating CX3CL1 in DKD and reveal its underlying mechanisms.

Methods

For the in vivo study, mice were divided into the following five groups (n=10): db/m+vehicle, db/db+vehicle, db/db+AS-IV-L (10mg/kg/d), db/db+AS-IV-M (20mg/kg/d), db/db+AS-IV-H (40mg/kg/d). After 12 weeks of treatment, the renal injuries were assessed based on the related parameters of urine, blood and histopathological examination. Immunohistochemistry and Western blotting were used to detect relative proteins levels. Then in HK-2 cells, the molecular mechanism of AS-IV attenuating the EMT in mice with DKD through the CX3CL1-RAF/MEK/ERK pathway was studied.

Results

In the present study, we found that AS-IV reduced urinary protein levels and improved renal pathological damage in DKD mice. Moreover, AS-IV ameliorated the renal tubular EMT induced by hyperglycemia or high glucose (HG), and decreased the expression of CX3CL1 and inhibited the activation of the RAF/MEK/ERK pathway in vivo and in vitro. In HK-2 cells, downregulation of CX3CL1 suppressed the stimulation of the RAF/MEK/ERK pathway and EMT induced by HG. However, CX3CL1 overexpression eliminated the benefits of AS-IV on the RAF/MEK/ERK pathway and EMT.

Conclusion

In summary, we indicated that AS-IV alleviates renal tubular EMT through the CX3CL1-RAF/MEK/ERK signaling pathway, indicating that CX3CL1 could be a potential therapeutic target of AS-IV in DKD.

Impact of klotho on the expression of SRGAP2a in podocytes in diabetic nephropathy

Background

Diabetic nephropathy (DN) is the major cause of kidney failure, and glomerular podocytes play critical roles in the pathogenesis of DN by maintaining the glomerular structure and filtration barrier. Klotho and Slit-Robo GTP activating protein 2a (SRGAP2a) have been indicated to play protective roles in reducing kidney injury, but whether there is an internal relationship between these two factors is unclear.

Methods

In this study, we cultured differentiated rat podocytes in vitro and measured the SRGAP2a expressions by immunofluorescence staining, quantitative real-time PCR (qRT-PCR) and western blotting, after siRNA-mediated transforming growth factor β1 (TGF-β1) silencing, TGF-β1 overexpression and in the presence of a reactive oxygen species (ROS) inhibitor. And we detected the expressions of SRGAP2a, small mother against decapentaplegic (Smad)2/3, phosphorylated-Smad2/3 (p-Smad2/3), Smad7, and NAD(P)H oxidase 4 (NOX4), ROS levels and podocyte cytoskeletal remodelling under high glucose (HG) and exogenous klotho conditions. In addition, we performed haematoxylin–eosin (HE) staining and immunohistochemistry with diabetic rat models to confirm the in vitro results.

Results

The results indicated that SRGAP2a expression was significantly upregulated under siRNA-mediated TGF-β1 silencing conditions or after adding a ROS inhibitor, but significantly downregulated with TGF-β1 overexpression, in the presence of HG. The supplementation of exogenous klotho under HG conditions significantly increased the SRGAP2a expression, remodelled the actin cytoskeleton and altered the expressions of Smad2/3, p-Smad2/3, Smad7 and NOX4 and reduced the ROS generation in podocytes. Moreover, klotho administration protected kidney injury in DN rats.

Conclusions

This study indicated that klotho may modulate the expression of SRGAP2a by regulating the ROS and TGF-β1 signalling pathways and provided theoretical support for klotho protein as a novel therapeutic strategy for treating DN patients.

Supplementary Information

The online version contains supplementary material available at 10.1186/s12882-022-02765-z.

Shikonin attenuates kidney tubular epithelial cells apoptosis, oxidative stress, and inflammatory response through nicotinamide adenine dinucleotide phosphate oxidase 4/PTEN pathway in acute kidney injury of sepsis model

Natural compounds were used in the treatment of acute kidney injury (AKI) caused by sepsis. This study investigated the function of shikonin from the roots of Arnebia purpurea in sepsis-induced AKI model. The target genes of shikonin were predicted by traditional Chinese medicine integrative database (TCMID). The markers of kidney injury, oxidative stress, and inflammatory factors were measured by enzyme-linked immunosorbent assay (ELISA). The pathological changes of kidney tubules were assessed by Hematoxylin and Eosin staining. Apoptosis of kidney tubular epithelial cells (KTECs) was detected by the terminal deoxynucleotidyl transferase-mediated dUTP nick end labeling. Protein expression was measured by western blot. Shikonin significantly improved kidney injury induced by cecal ligation and perforation (CLP). Besides, shikonin reduced KTECs apoptosis, malondialdehyde (MDA), reactive oxygen species (ROS), interleukin-1β (IL-1β), IL-6, and tumor necrosis factor-α (TNF-α) levels, while augmented SOD and IL-10 levels. Nicotinamide adenine dinucleotide phosphate (NADPH) oxidase4 (NOX4) was predicted a target gene of shikonin. The expression of NOX4 was significantly inhibited in shikonin-treated group and the levels of phosphatidylinositol 3,4,5-trisphosphate 3-phosphate and dual specificity protein phosphate (PTEN) and p-p65 were decreased, while level of p-Akt was elevated. In vitro experiments, shikonin inhibited cell apoptosis, inflammatory, and ROS in human HK-2 cells and rat TECs. Shikonin downregulated expression of NOX4, PTEN and p-p65, and upregulated p-AKT and Bcl-2 expression in HK2 cells treated with lipopolysaccharide (LPS). Moreover, overexpression of NOX4 enhanced the effect of LPS on the expression level of PTEN, p-p65, p-AKT, and Bcl-2, which was reversed by the addition of shikonin. Taken together, shikonin could improve sepsis-induced AKI in rats, and attenuate the LPS induced KTECs apoptosis, oxidative stress, and inflammatory reaction via modulating NOX4/PTEN/AKT pathway.

Antioxidant and Anti-inflammatory Properties of Resveratrol in Diabetic Nephropathy: A Systematic Review and Meta-analysis of Animal Studies

Background: Accumulated experimental evidence suggests that resveratrol may have an effect on diabetic nephropathy by inhibiting inflammation and decreasing oxidative stress. However, the credibility of the evidence for this practice is unclear. Thus, we aimed to perform a systematic review and meta-analysis of animal studies to evaluate the antioxidant and anti-inflammatory properties of resveratrol when used in the treatment of diabetic nephropathy.

Methods: Electronic bibliographic databases including PubMed, EMBASE, and Web of Science were searched for relevant studies. The methodological quality of animal studies was assessed based on the SYstematic Review Center for Laboratory animal Experimentation Risk of Bias (SYRCLE’s RoB) tool. A meta-analysis was performed based on the Cochrane Handbook for Systematic Reviews of Interventions by using RevMan 5.4 software. This study was registered within International Prospective Register of Systematic Reviews (PROSPERO) as number CRD42021293784.

Results: Thirty-six qualified studies involving 726 animals were included. There was a significant association of resveratrol with the levels of blood glucose (BG), serum creatinine (Scr), blood urea nitrogen (BUN), catalase (CAT), superoxide dismutase (SOD), malondialdehyde (MDA), glutathione (GSH), glutathione peroxidase (GPx), and interleukin-1β (IL-1β). Nevertheless, resveratrol treatment did not effectively decrease the levels of tumor necrosis factor-α (TNF-α) and interleukin-6 (IL-6). In addition, more remarkable antioxidant and hypoglycemic effects were observed in type 2 diabetic nephropathy rather than in type 1 diabetic nephropathy based on subgroup analysis.

Conclusion: In this meta-analysis, resveratrol can exert its antioxidant activities by reducing the levels of MDA and recovering the activities of SOD, CAT, GSH, and GPx. With regard to pro-inflammatory cytokines, resveratrol had a positive effect on the reduction of IL-1β. However, the analysis indicated that resveratrol had no effect on IL-6 and TNF-α levels, probably because of the methodological quality of the studies and their heterogeneity. Current evidence supports the antioxidant and anti-inflammatory properties of resveratrol, but its relationship with the levels of some inflammatory cytokines such as IL-6 and TNF-α in animals with diabetic nephropathy needs further elucidation.

EW-7197 Attenuates the Progression of Diabetic Nephropathy in db/db Mice through Suppression of Fibrogenesis and Inflammation

BACKGROUND

Diabetic nephropathy (DN) is characterized by albuminuria and accumulation of extracellular matrix (ECM) in kidney. Transforming growth factor-β (TGF-β) plays a central role in promoting ECM accumulation. We aimed to examine the effects of EW-7197, an inhibitor of TGF-β type 1 receptor kinase (ALK5), in retarding the progression of DN, both in vivo, using a diabetic mouse model (db/db mice), and in vitro, in podocytes and mesangial cells.

METHODS

In vivo study: 8-week-old db/db mice were orally administered EW-7197 at a dose of 5 or 20 mg/kg/day for 10 weeks. Metabolic parameters and renal function were monitored. Glomerular histomorphology and renal protein expression were evaluated by histochemical staining and Western blot analyses, respectively. In vitro study: DN was induced by high glucose (30 mM) in podocytes and TGF-β (2 ng/mL) in mesangial cells. Cells were treated with EW-7197 (500 nM) for 24 hours and the mechanism associated with the attenuation of DN was investigated.

RESULTS

Enhanced albuminuria and glomerular morphohistological changes were observed in db/db compared to that of the nondiabetic (db/m) mice. These alterations were associated with the activation of the TGF-β signaling pathway. Treatment with EW-7197 significantly inhibited TGF-β signaling, inflammation, apoptosis, reactive oxygen species, and endoplasmic reticulum stress in diabetic mice and renal cells.

CONCLUSION

EW-7197 exhibits renoprotective effect in DN. EW-7197 alleviates renal fibrosis and inflammation in diabetes by inhibiting downstream TGF-β signaling, thereby retarding the progression of DN. Our study supports EW-7197 as a therapeutically beneficial compound to treat DN.

AMPK signaling in diabetes mellitus, insulin resistance and diabetic complications: A pre-clinical and clinical investigation

Diabetes mellitus (DM) is considered as a main challenge in both developing and developed countries, as lifestyle has changed and its management seems to be vital. Type I and type II diabetes are the main kinds and they result in hyperglycemia in patients and related complications. The gene expression alteration can lead to development of DM and related complications. The AMP-activated protein kinase (AMPK) is an energy sensor with aberrant expression in various diseases including cancer, cardiovascular diseases and DM. The present review focuses on understanding AMPK role in DM. Inducing AMPK signaling promotes glucose in DM that is of importance for ameliorating hyperglycemia. Further investigation reveals the role of AMPK signaling in enhancing insulin sensitivity for treatment of diabetic patients. Furthermore, AMPK upregulation inhibits stress and cell death in β cells that is of importance for preventing type I diabetes development. The clinical studies on diabetic patients have shown the role of AMPK signaling in improving diabetic complications such as brain disorders. Furthermore, AMPK can improve neuropathy, nephropathy, liver diseases and reproductive alterations occurring during DM. For exerting such protective impacts, AMPK signaling interacts with other molecular pathways such as PGC-1α, PI3K/Akt, NOX4 and NF-κB among others. Therefore, providing therapeutics based on AMPK targeting can be beneficial for amelioration of DM.

Histone lysine-specific demethylase 1 induced renal fibrosis via decreasing sirtuin 3 expression and activating TGF-β1/Smad3 pathway in diabetic nephropathy

OBJECTIVE

Diabetic nephropathy (DN) is the leading cause of end-stage renal disease. Histone lysine-specific demethylase 1 (LSD1) is a flavin-containing amino oxidase that can repress or activate transcription. The aim of this study is to explore the mechanism of LSD1 aggravating DN-induced renal fibrosis.

METHODS

The STZ-induced DN rat model was established for in vivo study. The rats were divided into four groups: Sham, STZ, STZ + Ad-shNC and Ad-shLSD1. The Hematoxylin-eosin (HE) staining was used to evaluate the renal injury. The Immunofluorescence assay was used to determine the LSD1, Fibronectin and α-SMA expression. The related protein expression was detected by western blot.

RESULTS

Knockdown of LSD1 alleviated STZ-induced renal injury. Moreover, knockdown of LSD1 decreased the expression of serum biochemical markers, containing urine output (24 h), urinary protein (24 h), serum creatinine, BUN and UACR. Furthermore, we proved that knockdown of LSD1 alleviated renal fibrosis in STZ-induced DN rats. In vitro, knockdown of LSD1 suppressed NRK-49F cells activation and overexpression of LSD1 induced renal fibrosis. In addition, knockdown of LSD1 could deactivate TGF-β1/Smad3 pathway and promote sirtuin 3 (SIRT3) expression in vivo and in vitro. The rescue experiments confirmed that LSD1 induced renal fibrosis via decreasing SIRT3 expression and activating TGF-β1/Smad3 pathway.

CONCLUSION

LSD1 deficiency leads to alleviate STZ-induced renal injury and overexpression of LSD1 induces renal fibrosis via decreasing SIRT3 expression and activating TGF-β1/Smad3 pathway, which provides a reasonable strategy for developing novel drugs targeting LDS1 to block renal fibrosis.

Animal study of a newly designed metal airway brachytherapy stent loaded with radioactive 125I seeds

AIM

To evaluate dynamic tissue changes after airway stenting (AS) with a newly designed metal brachytherapy stent (BS) loaded with radioactive ¹²⁵I seeds in normal rabbits.

METHODS

Forty-five normal New Zealand white rabbits were divided into 3 groups (group A: stent without seeds; group B: stent with 0.4 mCi active seeds; group C: stent with 0.8 mCi active seeds) and underwent AS under C-arm guidance. Then, five rabbits were killed from each group at 2, 4, and 8 weeks for further examination. Laboratory tests (including routine blood tests, liver function, kidney function, and electrolytes), gross observations, and tissue changes of Masson/hematoxylin-eosin staining, plus immunohistochemistry of α-SMA, NOX4, and TGF-β were performed at each time point.

RESULTS

All animals underwent AS successfully without procedure-related death, but one animal died at 6 weeks due to severe pulmonary infection in group C. Apart from a transient increase in white blood cells (P < 0.05) and a gradual increase in ROS levels (P < 0.05), other blood test items showed no significant changes (P > 0.05). The brachytherapy injury score increased with irradiation dose accumulation (P < 0.05), but tissue hyperplasia at the stent end in group C was less severe than that in groups A and B (P < 0.05). Airway lateral fibrosis was observed in all groups by histopathologic analysis; however, fibrosis in group C was more severe than that in groups A and B (P < 0.05).

CONCLUSION

The brachytherapy injury score increased with irradiation dose accumulation, while granulation tissue hyperplasia at the stent end was inhibited by ¹²⁵I brachytherapy within 8 weeks.

Therapeutic potential of resveratrol in diabetic nephropathy according to molecular signaling

BACKGROUND

Diabetic nephropathy (DN) as a severe complication of diabetes mellitus (DM), is a crucial menace for human health and survival and remarkably elevates the healthcare systems' costs. Therefore, it is worth noting to identify novel preventive and therapeutic strategies to alleviate the disease conditions. Resveratrol, as a well-defined anti-diabetic/ antioxidant agent has capabilities to counteract diabetic complications. It has been predicted that resveratrol will be a fantastic natural polyphenol for diabetes therapy in the next few years.

OBJECTIVE

Accordingly, the current review aims to depict the role of resveratrol in the regulation of different signaling pathways that are involved in the reactive oxygen species (ROS) production, inflammatory processes, autophagy, and mitochondrial dysfunction, as critical contributors to DN pathophysiology.

RESULTS

The pathogenesis of DN can be multifactorial; hyperglycemia is one of the prominent risk factors of DN development that is closely related to oxidative stress. Resveratrol, as a well-defined polyphenol, has various biological and medicinal properties, including anti-diabetic, anti-inflammatory, and anti-oxidative effects.

CONCLUSION

Resveratrol prevents kidney damages that are caused by oxidative stress, enhances antioxidant capacity, and attenuates the inflammatory and fibrotic responses. For this reason, resveratrol is considered an interesting target in DN research due to its therapeutic possibilities during diabetic disorders and renal protection.

Jujuboside A ameliorates high fat diet and streptozotocin induced diabetic nephropathy via suppressing oxidative stress, apoptosis, and enhancing autophagy

Jujuboside A (JuA) is a triterpenoid saponins isolated from the seed of jujube (semen Ziziphi spinosae) with anti-oxidant, anti-inflammation and anti-apoptosis properties. The present study aimed to investigate the reno-protective effects of JuA on type II diabetes. JuA (20 mg/kg) and Metformin (Met, 300 mg/kg) were administrated to diabetic Sprague Dawley rat for 8 weeks daily. Our results showed that JuA reduced blood glucose and kidney function markers including 24 h urinary protein, urinary β-NAG/urinary creatinine, serum urea nitrogen, serum uric acid and serum creatinine, and relieved renal pathological changes. In addition, JuA decreased O₂^- and H₂O₂ level, enhanced SOD, CAT and GPx activities, decreased NOX4 expression and improved mitochondrial respiratory chain function through regulating respiratory chain complex expression. Moreover, JuA downregulated the expressions of mitochondrial apoptosis proteins: Bax, CytC, Apaf-1 and caspase 9. Apoptosis mediated by ER stress also been inhibited by JuA via downregulating p-PERK, p-IRE1, XBP1s, ATF4, p-CHOP and caspase 12 expressions. JuA also enhanced autophagy and mitophagy via regulating CaMKK2-AMPK-p-mTOR and PINK1/Parkin pathways. Collectively, these results indicated that JuA protected against type II diabetic nephropathy through inhibiting oxidative stress and apoptosis mediated by mitochondria and ER stress. In addition, autophagy and mitophagy was enhanced by JuA.

Role of Polyphenol in Regulating Oxidative Stress, Inflammation, Fibrosis, and Apoptosis in Diabetic Nephropathy

Diabetic nephropathy (DN) is known as one of the driving sources of end-stage renal disease (ESRD). DN prevalence continues to increase in every corner of the world andthat has been a major concern to healthcare professionals as DN is the key driver of diabetes mellitus (DM) morbidity and mortality. Hyperglycaemia is closely connected with the production of reactive oxygen species (ROS) that cause oxidative stress response as well as numerous cellular and molecular modifications. Oxidative stress is a significant causative factor to renal damage, as it can activate other immunological pathways, such as inflammatory, fibrosis, and apoptosis pathways. These pathways can lead to cellular impairment and death as well as cellular senescence. Natural substances containing bioactive compounds, such as polyphenols, have been reported to exert valuable effects on various pathological conditions, including DM. The role of polyphenols in alleviating DN conditions has been documented in many studies. In this review, the potential of polyphenols in ameliorating the progression of DN via modulation of oxidative stress, inflammation, fibrosis, and apoptosis, as well as cellular senescence, has been addressed. This information may be used as the strategies for the management of DN and development as nutraceutical products to overcome DN development.

Resveratrol against Cardiac Fibrosis: Research Progress in Experimental Animal Models

Cardiac fibrosis is a heterogeneous disease, which is characterized by abundant proliferation of interstitial collagen, disordered arrangement, collagen network reconstruction, increased cardiac stiffness, and decreased systolic and diastolic functions, consequently developing into cardiac insufficiency. With several factors participating in and regulating the occurrence and development of cardiac fibrosis, a complex molecular mechanism underlies the disease. Moreover, cardiac fibrosis is closely related to hypertension, myocardial infarction, viral myocarditis, atherosclerosis, and diabetes, which can lead to serious complications such as heart failure, arrhythmia, and sudden cardiac death, thus seriously threatening human life and health. Resveratrol, with the chemical name 3,5,4'-trihydroxy-trans-stilbene, is a polyphenol abundantly present in grapes and red wine. It is known to prevent the occurrence and development of cardiovascular diseases. In addition, it may resist cardiac fibrosis through a variety of growth factors, cytokines, and several cell signaling pathways, thus exerting a protective effect on the heart.

Pathomorphological sequence of nephron loss in diabetic nephropathy

Following our previous reports on mesangial sclerosis and vascular proliferation in diabetic nephropathy (DN) (Kriz W, Löwen J, Federico G, van den Born J, Gröne E, Gröne HJ. Am J Physiol Renal Physiol 312: F1101-F1111, 2017; Löwen J, Gröne E, Gröne HJ, Kriz W. Am J Physiol Renal Physiol 317: F399-F410, 2019), we now describe the advanced stages of DN terminating in glomerular obsolescence and tubulointerstitial fibrosis based on a total of 918 biopsies. The structural aberrations emerged from two defects: 1) increased synthesis of glomerular basement membrane (GBM) components by podocytes and endothelial cells leading to an accumulation of GBM material in the mesangium and 2) a defect of glomerular vessels consisting of increased leakiness and an increased propensity to proliferate. Both defects may lead to glomerular degeneration. The progressing compaction of accumulated worn-out GBM material together with the retraction of podocytes out of the tuft and the collapse and hyalinosis of capillaries results in a shrunken tuft that fuses with Bowman's capsule (BC) to glomerular sclerosis. The most frequent pathway to glomerular decay starts with local tuft expansions that result in contacts of structurally intact podocytes to the parietal epithelium initiating the formation of tuft adhesions, which include the penetration of glomerular capillaries into BC. Exudation of plasma from such capillaries into the space between the parietal epithelium and its basement membrane causes the formation of insudative fluid accumulations within BC spreading around the glomerular circumference and, via the glomerulotubular junction, onto the tubule. Degeneration of the corresponding tubule develops secondarily to the glomerular damage, either due to cessation of filtration in cases of global sclerosis or due to encroachment of the insudative spaces. The degenerating tubules induce the proliferation of myofibroblasts resulting in interstitial fibrosis.NEW & NOTEWORTHY Based on analysis of 918 human biopsies, essential derangement in diabetic nephropathy consists of accumulation of worn-out glomerular basement membrane in the mesangium that may advance to global sclerosis. The most frequent pathway to nephron dropout starts with the penetration of glomerular capillaries into Bowman's capsule (BC), delivering an exudate into BC that spreads around the entire glomerular circumference and via the glomerulotubular junction onto the tubule, resulting in glomerular sclerosis and chronic tubulointerstitial damage.

Therapeutic and delivery strategies of phytoconstituents for renal fibrosis

Chronic kidney disease (CKD) is one of the most common diseases endangering human health and life. By 2030, 14 per 100,000 people may die from CKD. Renal fibrosis (RF) is an important intermediate link and the final pathological change during CKD progression to the terminal stage. Therefore, identifying safe and effective treatment methods for RF has become an important goal. In 2018, the World Health Organization introduced traditional Chinese medicine into its effective global medical program. Various phytoconstituents that affect the RF process have been extracted from different plants. Here, we review the potential therapeutic capabilities of active phytoconstituents in RF treatment and discuss how phytoconstituents can be structurally modified or combined with other ingredients to enhance efficiency and reduce toxicity. We also summarize phytoconstituent delivery strategies to overcome renal barriers and improve bioavailability and targeting.

Backstage players of fibrosis: NOX4, mTOR, HDAC, and S1P; companions of TGF-β

The fibrotic process could be easily defined as a pathological excess of extracellular matrix deposition, leading to disruption of tissue architecture and eventually loss of function; however, this process involves a complex network of several signal transduction pathways. Virtually almost all organs could be affected by fibrosis, the most affected are the liver, lung, skin, kidney, heart, and eyes; in all of them, the transforming growth factor-beta (TGF-β) has a central role. The canonical and non-canonical signal pathways of TGF-β impact the fibrotic process at the cellular and molecular levels, inducing the epithelial-mesenchymal transition (EMT) and the induction of profibrotic gene expression with the consequent increase in proteins such as alpha-smooth actin (α-SMA), fibronectin, collagen, and other extracellular matrix proteins. Recently, it has been reported that some molecules that have not been typically associated with the fibrotic process, such as nicotinamide adenine dinucleotide phosphate (NADPH) oxidase 4 (NOX4), mammalian target of rapamycin (mTOR), histone deacetylases (HDAC), and sphingosine-1 phosphate (S1P); are critical in its development. In this review, we describe and discuss the role of these new players of fibrosis and the convergence with TGF-β signaling pathways, unveiling new insights into the panorama of fibrosis that could be useful for future therapeutic targets.

Prospective Pharmacological Potential of Resveratrol in Delaying Kidney Aging

Aging is an unavoidable part of life. The more aged we become, the more susceptible we become to various complications and damages to the vital organs, including the kidneys. The existing drugs for kidney diseases are mostly of synthetic origins; thus, natural compounds with minimal side-effects have attracted growing interest from the scientific community and pharmaceutical companies. A literature search was carried out to collect published research information on the effects of resveratrol on kidney aging. Recently, resveratrol has emerged as a potential anti-aging agent. This versatile polyphenol exerts its anti-aging effects by intervening in various pathologies and multi-signaling systems, including sirtuin type 1, AMP-activated protein kinase, and nuclear factor-κB. Researchers are trying to figure out the detailed mechanisms and possible resveratrol-mediated interventions in divergent pathways at the molecular level. This review highlights (i) the causative factors implicated in kidney aging and the therapeutic aspects of resveratrol, and (ii) the effectiveness of resveratrol in delaying the aging process of the kidney while minimizing all possible side effects.

Icariin Ameliorates Diabetic Renal Tubulointerstitial Fibrosis by Restoring Autophagy via Regulation of the miR-192-5p/GLP-1R Pathway

Tubulointerstitial fibrosis is one of the most common pathological features of diabetic nephropathy. Autophagy, an intracellular mechanism to remove damaged or dysfunctional cell parts and maintain metabolic homeostasis, is inhibited in diabetic neuropathy. Icariin is a traditional Chinese medicine extract known for nourishing the kidney and reinforcing Yang. In this study, we investigated the effects and mechanism of Icariin on renal function, autophagy, and fibrosis in type 2 diabetic nephropathic rats and in high-glucose-incubated human renal tubular epithelial cells and rat renal fibroblasts (in vitro). Icariin improved diabetes, renal function, restored autophagy, and alleviated fibrosis in type 2 diabetic neuropathic rats and in vitro. After we applied autophagy-related gene 5-small interfering RNA, we found that fibrosis improvement by Icariin was related to autophagy restoration. By detecting serum sex hormone levels, and using dihydrotestosterone, siRNA for androgen receptor, and the androgen receptor antagonist Apalutamide (ARN-509), we found that Icariin had an androgen-like effect and restored autophagy and reduced fibrosis by regulating the androgen receptor. In addition, miR-192-5p levels were increased under high glucose but reduced after dihydrotestosterone and Icariin treatment. Furthermore, dihydrotestosterone and Icariin inhibited miR-192-5p overexpression-induced fibrosis production and autophagy limitation. Glucagon-like peptide-1 receptor (GLP-1R) was downregulated by high glucose and overexpression of miR-192-5p and could be restored by dihydrotestosterone and Icariin. By using ARN-509, we found that Icariin increased GLP-1R expression by regulating the androgen receptor. GLP-1R-siRNA transfection weakened the effects of Icariin on autophagy and fibrosis. These findings indicate that Icariin alleviates tubulointerstitial fibrosis by restoring autophagy through the miR-192-5p/GLP-1R pathway and is a novel therapeutic option for diabetic fibrosis.

Fibrosis, the Bad Actor in Cardiorenal Syndromes: Mechanisms Involved

Cardiorenal syndrome is a term that defines the complex bidirectional nature of the interaction between cardiac and renal disease. It is well established that patients with kidney disease have higher incidence of cardiovascular comorbidities and that renal dysfunction is a significant threat to the prognosis of patients with cardiac disease. Fibrosis is a common characteristic of organ injury progression that has been proposed not only as a marker but also as an important driver of the pathophysiology of cardiorenal syndromes. Due to the relevance of fibrosis, its study might give insight into the mechanisms and targets that could potentially be modulated to prevent fibrosis development. The aim of this review was to summarize some of the pathophysiological pathways involved in the fibrotic damage seen in cardiorenal syndromes, such as inflammation, oxidative stress and endoplasmic reticulum stress, which are known to be triggers and mediators of fibrosis.

miR-451 on Myocardial Ischemia-Reperfusion in Rats by Regulating AMPK Signaling Pathway

Myocardial infarction is the main cause of death in patients with coronary heart disease. At present, the main method to treat cardiovascular disease is perfusion therapy. Myocardial ischemia-reperfusion will inevitably lead to reperfusion injury, which is also a major problem in the treatment of cardiovascular diseases. It has been reported that mir-451 in microRNA family participates in the protection of myocardial ischemia-reperfusion by regulating AMPK. The aim of this study was to investigate the effect of mir-451 on myocardial ischemia-reperfusion in rats by regulating AMPK signaling pathway. Sixty adult male rats were selected to establish myocardial ischemia-reperfusion animal model by ligating and loosening coronary artery. The expression level of mir-451 was regulated by injection of mir-451 virus vector and antibody, and the effect of increased or decreased mir-451 expression level on the activity of AMPK signaling pathway was detected. The myocardial infarct area and apoptosis rate of myocardial tissue were detected after 75 min ischemia-reperfusion. The results showed that when the expression level of mir-451 decreased by 15.7%, the activity index of AMPK signaling pathway was increased by 18.3%, the infarct area was reduced by 22.4%, and the apoptosis rate of myocardial cells was decreased by 25.2%. At the same time, the pathological structure of myocardial tissue was improved. Therefore, mir-451 is an inhibitor gene of AMPK signaling pathway. Reducing the expression of mir-451 can enhance the activity of AMPK signal pathway, and the increase of AMPK signal pathway activity is beneficial to reduce myocardial ischemia-reperfusion injury.