Astragaloside IV represses high glucose-induced mesangial cells activation by enhancing autophagy via SIRT1 deacetylation of NF-κB p65 subunit

Roles of Sirt1 and its modulators in diabetic microangiopathy: A review

Diabetic vascular complications include diabetic macroangiopathy and diabetic microangiopathy. Diabetic microangiopathy is characterised by impaired microvascular endothelial function, basement membrane thickening, and microthrombosis, which may promote renal, ocular, cardiac, and peripheral system damage in diabetic patients. Therefore, new preventive and therapeutic strategies are urgently required. Sirt1, a member of the nicotinamide adenine dinucleotide-dependent histone deacetylase class III family, regulates different organ growth and development, oxidative stress, mitochondrial function, metabolism, inflammation, and aging. Sirt1 is downregulated in vascular injury and microangiopathy. Moreover, its expression and distribution in different organs correlate with age and play critical regulatory roles in oxidative stress and inflammation. This review introduces the background of diabetic microangiopathy and the main functions of Sirt1. Then, the relationship between Sirt1 and different diabetic microangiopathies and the regulatory roles mediated by different cells are described. Finally, we summarize the modulators that target Sirt1 to ameliorate diabetic microangiopathy as an essential preventive and therapeutic measure for diabetic microangiopathy. In conclusion, targeting Sirt1 may be a new therapeutic strategy for diabetic microangiopathy.

A systematic review of astragaloside IV effects on animal models of diabetes mellitus and its complications

Context

Diabetes mellitus (DM) is one of the fastest-growing diseases worldwide; however, its pathogenesis remains unclear. Complications seriously affect the quality of life of patients in the later stages of diabetes, ultimately leading to suffering. Natural small molecules are an important source of antidiabetic agents.

Objective

Astragaloside IV (AS-IV) is an active ingredient of Astragalus mongholicus (Fisch.) Bunge. We reviewed the efficacy and mechanism of action of AS-IV in animal and cellular models of diabetes and the mechanism of action of AS-IV on diabetic complications in animal and cellular models. We also summarized the safety of AS-IV and provided ideas and rationales for its future clinical application.

Methods

Articles on the intervention in DM and its complications using AS-IV, such as those published in SCIENCE, PubMed, Springer, ACS, SCOPUS, and CNKI from the establishment of the database to February 2022, were reviewed. The following points were systematically summarized: dose/concentration, route of administration, potential mechanisms, and efficacy of AS-IV in animal models of DM and its complications.

Results

AS-IV has shown therapeutic effects in animal models of DM, such as alleviating gestational diabetes, delaying diabetic nephropathy, preventing myocardial cell apoptosis, and inhibiting vascular endothelial dysfunction; however, the potential effects of AS-IV on DM should be investigated.

Conclusion

AS-IV is a potential drug for the treatment of diabetes and its complications, including diabetic vascular disease, cardiomyopathy, retinopathy, peripheral neuropathy, and nephropathy. In addition, preclinical toxicity studies indicate that it appears to be safe, but the safe human dose limit is yet to be determined, and formal assessments of adverse drug reactions among humans need to be further investigated. However, additional formulations or structural modifications are required to improve the pharmacokinetic parameters and facilitate the clinical use of AS-IV.

Autophagy, Pyroptosis and Ferroptosis are Rising Stars in the Pathogenesis of Diabetic Nephropathy

Diabetic nephropathy (DN) is one of the most common microvascular complications in diabetes and can potentially develop into end-stage renal disease. Its pathogenesis is complex and not fully understood. Podocytes, glomerular endothelial cells (GECs), glomerular mesangial cells (GMCs) and renal tubular epithelial cells (TECs) play important roles in the normal function of glomerulus and renal tubules, and their injury is involved in the progression of DN. Although our understanding of the mechanisms leading to DN has substantially improved, we still need to find more effective therapeutic targets. Autophagy, pyroptosis and ferroptosis are programmed cell death processes that are associated with inflammation and are closely related to a variety of diseases. Recently, a growing number of studies have reported that autophagy, pyroptosis and ferroptosis regulate the function of podocytes, GECs, GMCs and TECs. This review highlights the contributions of autophagy, pyroptosis, and ferroptosis to DN injury in these cells, offering potential therapeutic targets for DN treatment.

Advances in oxidative stress in pathogenesis of diabetic kidney disease and efficacy of TCM intervention

Diabetic kidney disease (DKD) is a common complication of diabetes and has become the leading cause of end-stage kidney disease. The pathogenesis of DKD is complicated, and oxidative stress is considered as a core of DKD onset. High glucose can lead to increased production of reactive oxygen species (ROS) via the polyol, PKC, AGE/RAGE and hexosamine pathways, resulting in enhanced oxidative stress response. In this way, pathways such as PI3K/Akt, TGF-β1/p38-MAPK and NF-κB are activated, inducing endothelial cell apoptosis, inflammation, autophagy and fibrosis that cause histologic and functional abnormalities of the kidney and finally result in kidney injury. Presently, the treatment for DKD remains an unresolved issue. Traditional Chinese medicine (TCM) has unique advantages for DKD prevention and treatment attributed to its multi-target, multi-component, and multi-pathway characteristics. Numerous studies have proved that Chinese herbs (e.g., Golden Thread, Kudzuvine Root, Tripterygium glycosides, and Ginseng) and patent medicines (e.g., Shenshuaining Tablet, Compound Rhizoma Coptidis Capsule, and Zishen Tongluo Granule) are effective for DKD treatment. The present review described the role of oxidative stress in DKD pathogenesis and the effect of TCM intervention for DKD prevention and treatment, in an attempt to provide evidence for clinical practice.

Therapeutic application of traditional Chinese medicine in kidney disease: Sirtuins as potential targets

Sirtuins are a family of NAD+ III-dependent histone deacetylases that consists of seven family members, Sirt1-Sirt7, which regulate various signalling pathways and are involved in many critical biological processes of kidney diseases. Traditional Chinese medicine (TCM), as an essential part of the global healthcare system, has multi-component and multi-pathway therapeutic characteristics and plays a role in preventing and controlling various diseases. Through ongoing collaboration with modern medicine, TCM has recently achieved many remarkable advancements in theoretical investigation, mechanistic research, and clinical applications related to kidney diseases. Therefore, a comprehensive and systematic summary of TCM that focuses on sirtuins as the intervention target for kidney diseases is necessary. This review introduces the relationship between abnormal sirtuins levels and common kidney diseases, such as diabetic kidney disease and acute kidney injury. Based on the standard biological processes, such as inflammation, oxidative stress, autophagy, mitochondrial homeostasis, and fibrosis, which are underlying kidney diseases, comprehensively describes the roles and regulatory effects of TCM targeting the sirtuins family in various kidney diseases.

The role of autophagy in the treatment of type II diabetes and its complications: a review

Type II diabetes mellitus (T2DM) is a chronic metabolic disease characterized by prolonged hyperglycemia and insulin resistance (IR). Its incidence is increasing annually, posing a significant threat to human life and health. Consequently, there is an urgent requirement to discover effective drugs and investigate the pathogenesis of T2DM. Autophagy plays a crucial role in maintaining normal islet structure. However, in a state of high glucose, autophagy is inhibited, resulting in impaired islet function, insulin resistance, and complications. Studies have shown that modulating autophagy through activation or inhibition can have a positive impact on the treatment of T2DM and its complications. However, it is important to note that the specific regulatory mechanisms vary depending on the target organ. This review explores the role of autophagy in the pathogenesis of T2DM, taking into account both genetic and external factors. It also provides a summary of reported chemical drugs and traditional Chinese medicine that target the autophagic pathway for the treatment of T2DM and its complications.

Could Cyclosiversioside F Serve as a Dietary Supplement to Prevent Obesity and Relevant Disorders?

Obesity is the basis of numerous metabolic diseases and has become a major public health issue due to its rapidly increasing prevalence. Nevertheless, current obesity therapeutic strategies are not sufficiently effective, so there is an urgent need to develop novel anti-obesity agents. Naturally occurring saponins with outstanding bio-activities have been considered promising drug leads and templates for human diseases. Cyclosiversioside F (CSF) is a paramount multi-functional saponin separated from the roots of the food-medicinal herb Astragali Radix, which possesses a broad spectrum of bioactivities, including lowering blood lipid and glucose, alleviating insulin resistance, relieving adipocytes inflammation, and anti-apoptosis. Recently, the therapeutic potential of CSF in obesity and relevant disorders has been gradually explored and has become a hot research topic. This review highlights the role of CSF in treating obesity and obesity-induced complications, such as diabetes mellitus, diabetic nephropathy, cardiovascular and cerebrovascular diseases, and non-alcoholic fatty liver disease. Remarkably, the underlying molecular mechanisms associated with CSF in disease therapy have been partially elucidated, especially PI3K/Akt, NF-κB, MAPK, apoptotic pathway, TGF-β, NLRP3, Nrf-2, and AMPK, with the aim of promoting the development of CSF as a functional food and providing references for its clinical application in obesity-related disorders therapy.

Astragaloside IV attenuates high glucose-induced NF-κB-mediated inflammation through activation of PI3K/AKT-ERK-dependent Nrf2/ARE signaling pathway in glomerular mesangial cells

Inflammation is a key contributor to diabetic kidney disease pathogenesis, including reactive oxidation stress (ROS)-mediated nuclear factor-κB (NF-κB) signaling pathway. In this study, we examined the effect of Astragaloside IV (AS-IV) on anti-inflammatory and anti-oxidative properties under high glucose (HG) condition and the potential mechanism in glomerular mesangial cells (GMCs). We showed that AS-IV concentration-dependently reduced GMCs proliferation, restrained ROS release and hydrogen peroxide content, and suppressed pro-inflammatory cytokines as well as pro-fibrotic factors expression, which were associated with the inhibition of NF-κB and nuclear factor-erythroid 2-related factor 2 (Nrf2) signaling activation. Accordingly, both NF-κB overexpression by using RNA plasmid and Nrf2 gene silencing by using RNA interference weakened the ability of AS-IV to ameliorate HG-induced oxidative stress, inflammation, and cell proliferation. Furthermore, phosphatidylinositide 3-kinases (PI3K)/serine/threonine protein kinase (Akt) and extracellular regulated protein kinases (ERK) signaling pathway regulated the process of AS-IV-induced Nrf2 activation and antioxidant capacity, which evidenced by using PI3K inhibitor LY294002 or ERK inhibitor PD98059 that largely abolished the AS-IV efficacy. Taken together, these results indicated that AS-IV protected against HG-induced GMCs damage by inhibiting ROS/NF-kB-induced increases of inflammatory cytokines, fibrosis biomarkers, and cell proliferation via up-regulation of Nrf2-dependent antioxidant enzyme expression, which were mediated by PI3K/Akt and ERK signaling pathway activation.

Pharmacological Effects of Astragaloside IV: A Review

Astragaloside IV (AS-IV) is one of the main active components extracted from the Chinese medicinal herb Astragali and serves as a marker for assessing the herb's quality. AS-IV is a tetracyclic triterpenoid saponin in the form of lanolin ester alcohol and exhibits various biological activities. This review article summarizes the chemical structure of AS-IV, its pharmacological effects, mechanism of action, applications, future prospects, potential weaknesses, and other unexplored biological activities, aiming at an overall analysis. Papers were retrieved from online electronic databases, such as PubMed, Web of Science, and CNKI, and data from studies conducted over the last 10 years on the pharmacological effects of AS-IV as well as its impact were collated. This review focuses on the pharmacological action of AS-IV, such as its anti-inflammatory effect, including suppressing inflammatory factors, increasing T and B lymphocyte proliferation, and inhibiting neutrophil adhesion-associated molecules; antioxidative stress, including scavenging reactive oxygen species, cellular scorching, and regulating mitochondrial gene mutations; neuroprotective effects, antifibrotic effects, and antitumor effects.

From Xiaoke to diabetes mellitus: a review of the research progress in traditional Chinese medicine for diabetes mellitus treatment

Diabetes mellitus (DM) is a chronic metabolic disorder characterized by hyperglycemia resulting from insulin secretion defects or insulin resistance. The global incidence of DM has been gradually increasing due to improvements in living standards and changes in dietary habits, making it a major non-communicable disease that poses a significant threat to human health and life. The pathogenesis of DM remains incompletely understood till now, and current pharmacotherapeutic interventions are largely inadequate, resulting in relapses and severe adverse reactions. Although DM is not explicitly mentioned in traditional Chinese medicine (TCM) theory and clinical practice, it is often classified as "Xiaoke" due to similarities in etiology, pathogenesis, and symptoms. With its overall regulation, multiple targets, and personalized medication approach, TCM treatment can effectively alleviate the clinical manifestations of DM and prevent or treat its complications. Furthermore, TCM exhibits desirable therapeutic effects with minimal side effects and a favorable safety profile. This paper provides a comprehensive comparison and contrast of Xiaoke and DM by examining the involvement of TCM in their etiology, pathogenesis, treatment guidelines, and other relevant aspects based on classical literature and research reports. The current TCM experimental research on the treatment of DM by lowering blood glucose levels also be generalized. This innovative focus not only illuminates the role of TCM in DM treatment, but also underscores the potential of TCM in DM management.

The beneficial effects of astragaloside IV on ameliorating diabetic kidney disease

Diabetic kidney disease (DKD) has become the major cause of chronic kidney disease or end-stage renal disease. There is still a need for innovative treatment strategies for preventing, arresting, treating, and reversing DKD, and a plethora of scientific evidence has revealed that Chinese herbal monomers can attenuate DKD in multiple ways. Astragaloside IV (AS-IV) is one of the active ingredients of Astragalus membranaceus and was selected as a chemical marker in the Chinese Pharmacopeia for quality control purposes. An increasing amount of studies indicate that AS-IV is a promising novel drug for the treatment of DKD. AS-IV has been shown to improve DKD by combating oxidative stress, attenuating endoplasmic reticulum stress, regulating calcium homeostasis, alleviating inflammation, improving vascular function, improving epithelial to mesenchymal transition and so on. This review briefly summarizes the pathogenesis of DKD, systematically reviews the mechanisms by which AS-IV improves DKD, and aims to facilitate related pharmacological research and development to promote the utilization of Chinese herbal monomers in DKD.

Autophagy and its therapeutic potential in diabetic nephropathy

Diabetic nephropathy (DN), the leading cause of end-stage renal disease, is the most significant microvascular complication of diabetes and poses a severe public health concern due to a lack of effective clinical treatments. Autophagy is a lysosomal process that degrades damaged proteins and organelles to preserve cellular homeostasis. Emerging studies have shown that disorder in autophagy results in the accumulation of damaged proteins and organelles in diabetic renal cells and promotes the development of DN. Autophagy is regulated by nutrient-sensing pathways including AMPK, mTOR, and Sirt1, and several intracellular stress signaling pathways such as oxidative stress and endoplasmic reticulum stress. An abnormal nutritional status and excess cellular stresses caused by diabetes-related metabolic disorders disturb the autophagic flux, leading to cellular dysfunction and DN. Here, we summarized the role of autophagy in DN focusing on signaling pathways to modulate autophagy and therapeutic interferences of autophagy in DN.

Review of the pharmacological effects of astragaloside IV and its autophagic mechanism in association with inflammation

Astragalus membranaceus Bunge, known as Huangqi, has been used to treat various diseases for a long time. Astragaloside IV (AS-IV) is one of the primary active ingredients of the aqueous Huangqi extract. Many experimental models have shown that AS-IV exerts broad beneficial effects on cardiovascular disease, nervous system diseases, lung disease, diabetes, organ injury, kidney disease, and gynaecological diseases. This review demonstrates and summarizes the structure, solubility, pharmacokinetics, toxicity, pharmacological effects, and autophagic mechanism of AS-IV. The autophagic effects are associated with multiple signalling pathways in experimental models, including the PI3KI/Akt/mTOR, PI3K III/Beclin-1/Bcl-2, PI3K/Akt, AMPK/mTOR, PI3K/Akt/mTOR, SIRT1–NF-κB, PI3K/AKT/AS160, and TGF-β/Smad signalling pathways. Based on this evidence, AS-IV could be used as a replacement therapy for treating the multiple diseases referenced above.

Heidihuangwan alleviates renal fibrosis in rats with 5/6 nephrectomy by inhibiting autophagy

Renal fibrosis is a common pathway for the progression of various chronic kidney diseases (CKD), and the formation and deterioration will eventually lead to end-stage renal failure, which brings a heavy medical burden to the world. HeidihuangWan (HDHW) is a herbal formulation with stable and reliable clinical efficacy in the treatment of renal fibrosis. However, the mechanism of HDHW in treating renal fibrosis is not clear. In this study, we aimed to investigate the mechanism of HDHW to improve renal fibrosis. Wistar rats were randomly divided into the normal control group, 5/6 Nephrectomy group, astragaloside IV (AS-IV) group, HDHW group, and HDHW + IGF-1R inhibitor (JB1) group. Except for the normal control group, the rat renal fibrosis model was established by 5/6 nephrectomy and intervened with drugs for 8 weeks. Blood samples were collected to evaluate renal function. Hematoxylin-Eosin (HE), Periodic Acid-Schiff (PAS), Modified Masson’s Trichrome (Masson) staining were used to evaluate the pathological renal injury, and immunohistochemistry and Western blotting were used to detect the protein expression of renal tissue. The results showed that HDHW was effective in improving renal function and reducing renal pathological damage. HDHW down-regulated the levels of fibrosis marker proteins, including α-smooth muscle actin (α-SMA), vimentin, and transforming growth factors–β(TGF-β), which in turn reduced renal fibrosis. Further studies showed that HDHW down-regulated the expression of autophagy-related proteins Beclin1 and LC3II, indicating that HDHW inhibited autophagy. In addition, we examined the activity of the class I phosphatidylinositol-3 kinase (PI3K)/serine-threonine kinase (Akt)/mTOR pathway, an important signaling pathway regulating autophagy, and the level of insulin-like growth factor 1 (IGF-1), an upstream activator of PI3K/Akt/mTOR. HDHW upregulated the expression of IGF-1 and activated the PI3K/Akt/mTOR pathway, which may be a vital pathway for its inhibition of autophagy. Application of insulin-like growth factor 1 receptor (IGF-1R) inhibitor further confirmed that the regulation of autophagy and renal fibrosis by HDHW was associated with IGF-1-mediated activation of the PI3K/Akt/mTOR pathway. In conclusion, our study showed that HDHW inhibited autophagy by upregulating IGF-1 expression, promoting the binding of IGF-1 to IGF-1R, and activating the PI3K/Akt/mTOR signaling pathway, thereby reducing renal fibrosis and protecting renal function. This study provides support for the application and further study of HDHW.

Astragalus Mongholicus: A review of its anti-fibrosis properties

Background: Fibrosis-related diseases (FRD) include cerebral fibrosis, pulmonary fibrosis, cardiac fibrosis, liver fibrosis, renal fibrosis, peritoneal fibrosis, etc. The effects of fibrosis can be severe, resulting in organ dysfunction, functional decline, and even organ failure, which can cause serious health problems.

Aim: Currently, there is no effective modern medicine for anti-fibrosis in the clinics; however, Chinese medicine has a certain beneficial effect on treating such diseases. Astragalus Mongholicus (AM) has rich medicinal value, and its anti-fibrosis effect has been recently investigated. In recent years, more and more experimental studies have been conducted on the intervention of astragaloside IV (AS-IV), astragalus polysaccharide (APS), astragalus flavone, cycloastragalus alcohol, astragalus water extract and other pharmacological components in fibrosis-related diseases, attracting the interest of researchers. We aim to provide ideas for future research by summarizing recent research advances of AM in treating fibrosis-related diseases.

Methods: A literature search was conducted from the core collections of electronic databases such as Baidu Literature, Sciencen.com, Google Scholar, PubMed, and Science Direct using the above keywords and the pharmacological and phytochemical details of the plant.

Results: AM can be used to intervene in fibrosis-disease progression by regulating inflammation, oxidative stress, the immune system, and metabolism.

Conclusion: AS-IV, APS, and astragalus flavone were studied and discussed in detail. These components have high potential anti-fibrosis activity. Overall, this review aims to gain insight into the AM’s role in treating fibro-related diseases.

The critical role of dysregulated autophagy in the progression of diabetic kidney disease

Diabetic kidney disease (DKD) is one of the major public health problems in society today. It is a renal complication caused by diabetes mellitus with predominantly microangiopathy and is a major cause of end-stage renal disease (ESRD). Autophagy is a metabolic pathway for the intracellular degradation of cytoplasmic products and damaged organelles and plays a vital role in maintaining homeostasis and function of the renal cells. The dysregulation of autophagy in the hyperglycaemic state of diabetes mellitus can lead to the progression of DKD, and the activation or restoration of autophagy through drugs is beneficial to the recovery of renal function. This review summarizes the physiological process of autophagy, illustrates the close link between DKD and autophagy, and discusses the effects of drugs on autophagy and the signaling pathways involved from the perspective of podocytes, renal tubular epithelial cells, and mesangial cells, in the hope that this will be useful for clinical treatment.

FGF21 improves LPS-induced pulmonary microvascular endothelial cell dysfunction and inflammatory response through SIRT1-mediated NF-κB deacetylation

Pneumonia is a common infectious disease of the respiratory system in children. It often leads to death in children by causing acute lung injury. Fibroblast growth factor 21 (FGF21) is a peptide hormone that plays important role in the regulation of energy homeostasis. This study aimed to investigate the role of FGF21 in alleviating the lipopolysaccharide (LPS)-induced human pulmonary microvascular endothelial cell (HPMEC) injury, as well as the underlying mechanism. The expression of SIRT1, NF-κB p65, Ac-NF-κB p65, apoptosis-related proteins, tight junction proteins and adhesion molecules in HPMECs. The viability and apoptosis of HPMECs was detected by CCK-8 and Tunel assays. LDH level and levels of inflammatory factors were respectively determined by assay kits. The mRNA expression of adhesion molecules in HPMECs was analyzed by RT-qPCR. As a result, SIRT1 expression was decreased and expression of NF-κB p65 and Ac-NF-κB p65 was increased in LPS-induced HPMECs, which were reversed by rFGF21. rFGF21 increased the viability and inhibited the apoptosis, inflammatory response, permeability and release of cell adhesion molecules of LPS-induced HPMECs. In addition, EX527 as SIRT1 inhibitor, could reversed the effect of rFGF21 on LPS-induced HPMECs. In conclusion, FGF21 improved LPS-induced HPMECs dysfunction and inflammatory response through SIRT1-mediated NF-κB deacetylation.

Astragaloside-IV alleviates high glucose-induced ferroptosis in retinal pigment epithelial cells by disrupting the expression of miR-138-5p/Sirt1/Nrf2

Astragaloside-IV (AS-IV) (C₄₁H₆₈O₁₄) is a high-purity natural product extracted from Astragalus, which has demonstrated biological activities. However, the effect of AS-IV on retinal pigment epithelial (RPE) cells in diabetic retinopathy (DR) remains unclear. In this study, high glucose (HG) was shown to promote ARPE-19 RPE cell death, increase the contents of reactive oxygen species (ROS) and oxidized glutathione (GSSG), and enhance lipid peroxidation density of mitochondrial membrane. In contrast, AS-IV decreased glutathione (GSH) content, mitochondria size and ridge. Addition of iron death inhibitor Ferrostatin-1 (Fer-1) to RPE cells decreased cell dead rate, thus indicating that HG-induced mitochondrial damage occurred due to ferroptosis. AS-IV alleviated HG-induced RPE cell damage. Furthermore, HG decreased levels of silent information regulator 1 (Sirt1) and nuclear factor (erythroid-derived 2)-like 2 (Nrf2) in the nucleus of RPE cells; AS-IV could alleviate these effects and increased expression of glutathione peroxidase 4 (GPX4), glutamate cysteine ligase (GCLM) and glutamate cysteine ligase catalytic subunit (GCLC), which are Nrf2 downstream genes. Mechanistically, AS-IV was shown to alleviate the effects of HG by increasing mir-138-5p expression in RPE cells and promoting expression of Sirt1 and Nrf2 in the nucleus. Transfection of mir-138-5p agonist inhibited the regulatory effects of AS-IV on Sirt1 and Nrf2, accompanied by decreased GPX4, GCLM and GCLC levels, and restoration of ferroptosis-related changes. Collectively, HG increased ferroptosis rate in RPE cells. In addition, AS-IV inhibited miR-138-5p expression, subsequently increasing Sirt1/Nrf2 activity and cellular antioxidant capacity to alleviate ferroptosis, resulting decreased cell death, which potentially inhibits the DR pathological process.

Potential of Polyphenols to Restore SIRT1 and NAD+ Metabolism in Renal Disease

SIRT1 is an NAD⁺-dependent class III histone deacetylase that is abundantly expressed in the kidney, where it modulates gene expression, apoptosis, energy homeostasis, autophagy, acute stress responses, and mitochondrial biogenesis. Alterations in SIRT1 activity and NAD⁺ metabolism are frequently observed in acute and chronic kidney diseases of diverse origins, including obesity and diabetes. Nevertheless, in vitro and in vivo studies and clinical trials with humans show that the SIRT1-activating compounds derived from natural sources, such as polyphenols found in fruits, vegetables, and plants, including resveratrol, quercetin, and isoflavones, can prevent disease and be part of treatments for a wide variety of diseases. Here, we summarize the roles of SIRT1 and NAD⁺ metabolism in renal pathophysiology and provide an overview of polyphenols that have the potential to restore SIRT1 and NAD⁺ metabolism in renal diseases.

SIRT1-SIRT7 in Diabetic Kidney Disease: Biological Functions and Molecular Mechanisms

Diabetic kidney disease (DKD) is a severe microvascular complication in patients with diabetes and is one of the main causes of renal failure. The current clinical treatment methods for DKD are not completely effective, and further exploration of the molecular mechanisms underlying the pathology of DKD is necessary to improve and promote the treatment strategy. Sirtuins are class III histone deacetylases, which play an important role in many biological functions, including DNA repair, apoptosis, cell cycle, oxidative stress, mitochondrial function, energy metabolism, lifespan, and aging. In the last decade, research on sirtuins and DKD has gained increasing attention, and it is important to summarize the relationship between DKD and sirtuins to increase the awareness of DKD and improve the cure rates. We have found that miRNAs, lncRNAs, compounds, or drugs that up-regulate the activity and expression of sirtuins play protective roles in renal function. Therefore, in this review, we summarize the biological functions, molecular targets, mechanisms, and signaling pathways of SIRT1-SIRT7 in DKD models. Existing research has shown that sirtuins have the potential as effective targets for the clinical treatment of DKD. This review aims to lay a solid foundation for clinical research and provide a theoretical basis to slow the development of DKD in patients.

GSDMD-mediated pyroptosis: a critical mechanism of diabetic nephropathy

Pyroptosis is a recently identified mechanism of programmed cell death related to Caspase-1 that triggers a series of inflammatory reactions by releasing several proinflammatory factors such as IL-1β and IL-18. The process is characterised by the rupture of cell membranes and the release of cell contents through the mediation of gasdermin (GSDM) proteins. GSDMD is an important member of the GSDM family and plays a critical role in the two pathways of pyroptosis. Diabetic nephropathy (DN) is a microvascular complication of diabetes and a major cause of end-stage renal disease. Recently, it was revealed that GSDMD-mediated pyroptosis plays an important role in the occurrence and development of DN. In this review, we focus on two types of kidney cells, tubular epithelial cells and renal podocytes, to illustrate the mechanism of pyroptosis in DN and provide new ideas for the prevention, early diagnosis and molecular therapy of DN.

Hypoglycemic effect of astragaloside IV via modulating gut microbiota and regulating AMPK/SIRT1 and PI3K/AKT pathway

ETHNOPHARMACOLOGICAL RELEVANCE

Radix Astragali, the dried root of Astragalus mongholicus Bunge, has long been used in traditional Chinese Medicine to treat diabetes. Astragaloside IV (AS-IV), one of the most active ingredients in the root, has been shown to have anti-diabetes ability; however, its underlying mechanism is still unclear.

MATERIALS AND METHODS

In this study, we evaluated the hypoglycemic effect and possible mechanisms of AS-IV in diabetic mice and insulin resistance-HepG2 cells. The components of the intestinal microflora in mice with type 2 diabetes mellitus (T2DM) were determined using high-throughput 16S rRNA gene sequencing. Moreover, the molecular mechanisms of specific members of insulin signaling pathways were analyzed.

RESULTS

AS-IV significantly reversed the abnormalities in blood lipids, glucose, insulin resistance, as well as oxidative stress levels in T2DM mice. Histological finding showed that AS-IV could protect the cellular architecture of the liver and pancreas. AS-IV also regulated the abundance and diversity of intestinal flora of T2DM mice in a positive direction and increased butyric acid levels. The active role of AS-IV as an anti-diabetic compound by regulating the AMPK/SIRT1 and PI3K/AKT signaling pathways was revealed using a T2DM model and verified through the intervention of inhibitors using insulin-resistance HepG2 cells.

CONCLUSION

Our results suggested that AS-IV may be used as an anti-diabetic drug candidate owing to its effects of regulating gut microbiota and AMPK/SIRT1 and PI3K/AKT signaling pathways.

Therapeutic effect and mechanism of combined use of FGF21 and insulin on diabetic nephropathy

Although FGF21 ameliorates diabetic nephropathy (DN), the efficacy is not satisfactory. Studies demonstrate that FGF21 combined with Insulin exhibits reciprocal sensitization on glucose and lipid metabolism in mice with type 2 diabetes. However, therapeutic effect of combined use of FGF21 and Insulin on DN has not been reported. Therefore, this study explored therapeutic effect and mechanism of combined use of FGF21 and Insulin on DN. Our results showed that compared with Insulin or FGF21 alone, FGF21 combined with Insulin further ameliorated blood glucose, HbAlc, OGTT, renal function, liver function, blood lipid, histopathological changes, oxidative stress and AGEs in the mice of DN (BKS-Lepr^em2Cd479/Gpt). Moreover, FGF21 combined with Insulin further reduced expressions of IL-1β, IL-6, TNF-α via promoting M1 type macrophage into M2 type macrophage. Results of real-time PCR and Western blot showed that FGF21 combined with Insulin upregulated the expressions of autophagy related genes LC3-Ⅱ and BCL-1. Mesangial cells play an important role in the pathological changes of DN mice. However, the effect of FGF21 on mesangial cells has not been reported. In this study, d-glucose was used in high glucose (HG) model in mesangial cells. The results showed that FGF21 significantly reduced the levels of OS, AGEs and cell overproliferation. Meanwhile, FGF21 significantly ameliorated autophagy level via upregulating the phosphorylation of AMPK and downregulating phosphorylation of mTOR. These effects were reversed in siRNA-β-klotho transfected mesangial cells. In conclusion, our results demonstrate that combination FGF21 with Insulin exhibits a better therapeutic effect on DN compared with FGF21 or Insulin alone. This study provides a theoretical basis for combined used of FGF21 and Insulin as a new treatment for DN and further provides theoretical support for application of FGF21 in treatment of DN.

Quercetin-mediated SIRT1 activation attenuates collagen-induced mice arthritis

ETHNOPHARMACOLOGICAL RELEVANCE

Herba taxilli (HT, Sangjisheng in Chinese), which is composed of the dried stems and leaves of Taxillus chinensis (DC.) Danser, has been commonly used to treat inflammation and arthritis in traditional Chinese medicine (TCM). Quercetin (Que) is a major active flavonoid component isolated from HT and is one of the quality control indexes of HT. In the clinical practice of TCM, formulas containing HT are commonly used to treat rheumatoid arthritis (RA). Recent studies have shown that Que exerts antiarthritic effects. However, the mechanism by which Que treatment affects RA is not fully understood.

AIM OF THE STUDY

This study aimed to explore the antiarthritic activity of Que in a collagen-induced arthritis (CIA) mouse model and investigate the underlying mechanisms.

MATERIALS AND METHODS

The antiarthritic activity of Que was evaluated in a CIA mouse model by determining the paw clinical arthritis scores and left ankle thicknesses and by conducting micro-PET imaging and histopathological analysis of ankle joint tissues. The proinflammatory cytokine (IL-6, TNF-α, IL-1β, IL-8, IL-13, IL-17) levels in the serum and ankle joint tissues were measured by ELISA. Mitochondrial oxidative stress was assessed by biochemical methods. Mitochondrial biogenesis was analysed by RT-qPCR. The protein levels of silent information regulator 1 (SIRT1), peroxisome proliferator-activated receptor γ coactivator-1α (PGC-1α), nuclear respiratory factor 1 (NRF1), mitochondrial transcription factor A (TFAM), high-mobility group box 1 (HMGB1), Toll-like receptor 4 (TLR4), p38, phospho-p38, extracellular signal-regulated kinases (ERK)-1/2, phospho-ERK1/2, p65, and phospho-p65 in ankle joint tissues were detected by Western blot analysis. A total of 30 RA patients were recruited to investigate the relationship between the disease activity score (DAS28) and the SIRT1, PGC-1α, NRF1, and HMGB1 plasma levels.

RESULTS

Que treatment decreased the clinical score and left ankle thickness of CIA mice, attenuated the synovial inflammation and hyperplasia and bone/cartilage destruction in ankle joints, and decreased the secretion of IL-6, TNF-α, IL-1β, IL-8, IL-13, and IL-17. Mechanistically, Que treatment improved impaired mitochondrial biogenesis and mitochondrial function by regulating the SIRT1/PGC-1α/NRF1/TFAM pathway and inhibited inflammation via the HMGB1/TLR4/p38/ERK1/2/NF-κB p65 pathway. Notably, epidemiological data revealed correlations between abnormal circulating levels of SIRT1, PGC-1α, NRF1, HMGB1 and RA disease activity in patients.

CONCLUSIONS

Our data suggested a potential role of Que as a dietary therapeutic drug for RA treatment that may act through SIRT1 to target mitochondrial biogenesis. Additionally, the role of impaired mitochondrial biogenesis in RA was evaluated.

Dapagliflozin ameliorates pancreatic injury and activates kidney autophagy by modulating the AMPK/mTOR signaling pathway in obese rats

Chronic consumption of a high-fat diet induces obesity and impairs the ultra-structure of organs and tissues. We examined the effect of sodium-glucose cotransporter 2 (SGLT2) inhibitor-dapagliflozin on renal and pancreatic injuries in obese condition. Rats were fed a high-fat diet for 16 weeks to induce obesity. After that, dapagliflozin or vildagliptin, 1.0 or 3.0 mg/kg/day, respectively, was administered by oral gavage for 4 weeks. The effects of dapagliflozin on insulin resistance, kidney autophagy, pancreatic oxidative stress, endoplasmic reticulum (ER) stress, inflammation, and apoptosis in high-fat diet-induced obese rats were elucidated. High-fat-diet fed rats demonstrated metabolic abnormalities including increased body weight, visceral fat weight, plasma insulin, plasma cholesterol, homeostasis model assessment (HOMA) index, and TAUCg, indicating the obese-insulin resistant and glucose intolerance conditions. Also, high-fat-diet fed rats exhibited significant pancreatic injury accompanied by decreased kidney autophagy. Dapagliflozin or vildagliptin treatment for 4 weeks ameliorated pancreatic oxidative stress, ER stress, inflammation, and apoptosis and restored kidney autophagy in obese rats. Moreover, the morphology changes of the pancreas and kidney were improved in the treated groups. Interestingly, dapagliflozin showed higher efficacy than vildagliptin in improving body weight, visceral fat weight, plasma cholesterol level, and pancreatic oxidative stress in our model. Taken together, the present study demonstrated that the therapeutic effects of dapagliflozin attenuated pancreatic injury, pancreatic oxidative stress, ER stress, inflammation, apoptosis, and exerted renoprotective effects by restoring autophagic signaling in obese rats.

Astragaloside IV attenuates IL-1β secretion by enhancing autophagy in H1N1 infection

Excessive secretion of inflammatory factors (cytokine storm) plays a significant role in H1N1-induced acute pneumonia, and autophagy acts as a cell-intrinsic mechanism to regulate inflammation. Astragaloside IV (AS-IV), originating from the astragalus root, possesses multiple pharmacological activities, such as anti-inflammation. However, the influences of AS-IV on H1N1-induced autophagy and inflammation have remained elusive. It has been reported that H1N1 infection leads to the accumulation of autophagosomes but obstructs autophagosomes incorporating into lysosomes, whereas the present study showed that AS-IV enhanced autophagy activation in H1N1 infection. Furthermore, we found that AS-IV promoted H1N1-triggered formation of autophagosomes and autolysosomes. Additionally, it was noted that AS-IV did not affect viral replication, mRNA level of interleukin-1 beta (IL-1β) and pro-IL-1β protein level, but significantly decreased secretion of IL-1β, and chloroquine (CQ, as an inhibitor of autophagy) increased secretion of IL-1β in H1N1 infection. In conclusion, AS-IV stimulates the formation of autophagosomes and the fusion of autophagosomes and lysosomes in H1N1 infection and may lead to decreased IL-1β secretion.

PARP-1 and SIRT-1 are Interacted in Diabetic Nephropathy by Activating AMPK/PGC-1α Signaling Pathway

INTRODUCTION

Diabetic nephropathy (DN) is a metabolic disorder characterized by the accumulation of extracellular matrix (ECM). This study aims to investigate whether exists an interplay between poly (ADP-ribose) polymerase 1 (PARP-1) and sirtuin 1 (SIRT-1) in DN via AMP-activated protein kinase (AMPK)/peroxisome proliferator-activated receptor gamma coactivator 1-α (PGC-1α) signaling pathway.

METHODS

Eight-week-old male obese leptin-resistant (db/db) mice and nondiabetic control male C57BLKs/J (db/m) mice were used in this study. Body weight and blood glucose were evaluated after 6 h of fasting, which continues for 4 weeks. The kidney tissues were dissected for Western blot, immunofluorescence (IF) assay. Besides, PARP activity assay, MTT assay, NAD⁺ qualification, Western blot and IF were also performed to detect the level and relation of PARP-1 and SIRT-1 in mouse mesangial cells (MCs) with or without high glucose followed by inhibiting or elevating PARP-1 and SIRT-1, respectively.

RESULTS

Western blotting shows PARP-1 and ECM marker fibronectin (FN) are upregulated while SIRT-1 is downregulated in db/db mice (p<0.05) or in mouse MCs with high glucose (p<0.05), which are significantly restored by PARP-1 inhibitor (PJ34) (p<0.05) and SIRT-1 lentiviral transfected treatment (p<0.05), or worsened by SIRT-1 inhibitor EX527 (p<0.05). PJ34 treatment (p < 0.05) or SIRT-1 overexpression (p < 0.05) could increase PGC-1α and p-AMPK levels, concomitant with down expression of FN, however, were reversed in the presence of EX527 (p<0.05).

DISCUSSION

Our results suggest an important relationship between PARP-1 and SIRT-1 through AMPK-PGC-1α pathway, indicating a potential therapeutic method for DN.

Ginsenoside Rg1 Alleviates Podocyte Injury Induced by Hyperlipidemia via Targeting the mTOR/NF-κB/NLRP3 Axis

Background

Podocyte injury plays an important role in diabetic nephropathy (DN). The aim of this study was to determine the potential therapeutic effects of the ginsenoside Rg1 on hyperlipidemia-stressed podocytes and elucidate the underlying mechanisms.

Methods

In vitro and in vivo models of DN were established as previously described, and the expression levels of relevant markers were analyzed by Western blotting, real-time Polymerase Chain Reaction (PCR), immunofluorescence, and immunohistochemistry.

Results

Ginsenoside Rg1 alleviated pyroptosis in podocytes cultured under hyperlipidemic conditions, as well as in the renal tissues of diabetic rats, and downregulated the mammalian target of rapamycin (mTOR)/NF-κB pathway. In addition, Rg1 also inhibited hyperlipidemia-induced NLRP3 inflammasome in the podocytes, which was abrogated by the mTOR activator L-leucine (LEU). The antipyroptotic effects of Rg1 manifested as improved renal function in the DN rats.

Conclusion

Ginsenoside Rg1 protects podocytes from hyperlipidemia-induced damage by inhibiting pyroptosis through the mTOR/NF-κB/NLRP3 axis, indicating a potential therapeutic function in DN.

In Silico Prediction of Molecular Targets of Astragaloside IV for Alleviation of COVID-19 Hyperinflammation by Systems Network Pharmacology and Bioinformatic Gene Expression Analysis

Introduction

The overproduction of cytokines and chemokines caused by excessive and uncontrolled inflammation contributes to the development of COVID-19. Astragaloside IV is considered as an anti-inflammatory and antioxidant agent. This study aimed at undertaking a network pharmacology approach and bioinformatics analysis to uncover the pharmacological mechanisms of Astragaloside IV on COVID-19.

Methods

Potential targets of Astragaloside IV were screened from public databases. Differentially expressed genes (DEGs) in SARS-CoV-2 were screened using bioinformatics analysis on the Gene Expression Omnibus (GEO) datasets GSE147507. Gene ontology (GO) and Kyoto Encyclopedia of Genes and Genomes (KEGG) pathway enrichment analyses were subsequently performed. The overlapping genes, GO terms and KEGG pathways between Astragaloside IV targets and SARS-CoV-2 DEGs were confirmed, and the location of overlapping targets in the key pathways was queried using KEGG Mapper.

Results

A total of 425 potential targets of Astragaloside IV were screened. Besides, a total of 546 DEGs were identified between SARS-CoV-2 infected samples and control samples, including 380 up-regulated and 166 down-regulated genes. There was a significant overlap in GO terms and KEGG pathways between Astragaloside IV targets and SARS-CoV-2 DEGs. The shared genes included MMP13, NLRP3, TRIM21, GBP1, ADORA2A, PTAFR, TNF, MLNR, IL1B, NFKBIA, ADRB2, and IL6.

Conclusions

This study is the first to propose Astragaloside IV as a new drug candidate for alleviating hyper-inflammation in COVID-19 patients. Besides, the key targets and pathways may reveal the main pharmacological mechanism of Astragaloside IV in the treatment of COVID-19.

Renal protective effects of astragaloside IV, in diabetes mellitus kidney damage animal models: A systematic review, meta-analysis

Astragaloside IV (ASIV) is the essential active component of astragalus that has diverse biological activities. Previous research has suggested its potentially beneficial effects on diabetic nephropathies. However, its effects and protective mechanism remain unclear. In this study, we conducted a preclinical systematic review to evaluate the efficacy and potential mechanisms of ASIV in reducing kidney damage in diabetes mellitus (DM) models. Studies were searched from nine databases until January 2020. A random-effects model was used to calculate combined standardised mean difference estimates and 95 % confidence intervals. Risk of bias of studies was assessed using the Systematic Review Center for Laboratory Animal Experimentation risk of bias tool 10-item checklist. RevMan 5.3 software was used for statistical analysis. Twenty-three studies involving 562 animals were included in the meta-analysis. Studies quality scores ranged from 2 to 5. The ASIV group induced a marked decrease in serum creatinine (P < 0.00001), blood urea nitrogen (P < 0.00001), 24-h urine protein (P < 0.00001) and pathological score (P < 0.001) compared with the control group. The determined potential mechanisms of ASIV action were relieving oxidative stress, delaying renal fibrosis, anti-apoptosis and anti-inflammatory action. We conclude that ASIV exerts renal protective effects in animals with DM through multiple signalling pathways.

Autophagy in kidney homeostasis and disease

Autophagy is a conserved lysosomal pathway for the degradation of cytoplasmic components. Basal autophagy in kidney cells is essential for the maintenance of kidney homeostasis, structure and function. Under stress conditions, autophagy is altered as part of the adaptive response of kidney cells, in a process that is tightly regulated by signalling pathways that can modulate the cellular autophagic flux - mammalian target of rapamycin, AMP-activated protein kinase and sirtuins are key regulators of autophagy. Dysregulated autophagy contributes to the pathogenesis of acute kidney injury, to incomplete kidney repair after acute kidney injury and to chronic kidney disease of varied aetiologies, including diabetic kidney disease, focal segmental glomerulosclerosis and polycystic kidney disease. Autophagy also has a role in kidney ageing. However, questions remain about whether autophagy has a protective or a pathological role in kidney fibrosis, and about the precise mechanisms and signalling pathways underlying the autophagy response in different types of kidney cells and across the spectrum of kidney diseases. Further research is needed to gain insights into the regulation of autophagy in the kidneys and to enable the discovery of pathway-specific and kidney-selective therapies for kidney diseases and anti-ageing strategies.

Transcriptomic Analysis Reveals the Protection of Astragaloside IV against Diabetic Nephropathy by Modulating Inflammation

Background

Diabetic nephropathy (DN) is one of the leading causes of end-stage kidney disease. Recently, there is no specific drug available to block the kidney damage. Astragaloside IV (AS-IV) is a major active component of Astragalus membranaceus (Fisch) Bge and has been demonstrated to benefit the kidney functions. This study explores the potential pharmacological action of AS-IV in DN of rats.

Methods

Male Sprague-Dawley rats were fed with high-fat diet and injected with streptozotocin to induce diabetes. The diabetic rats were randomized and treated with vehicle or AS-IV (80 mg/kg) daily by gavage for 12 weeks as the DN or AS-IV group, respectively. The normal control rats were fed with normal chow and injected with vehicles (n = 8 per group). These rats were monitored for diabetes- and kidney function-related measures. The expression profiles of gene mRNA transcripts in the kidney tissues were analyzed by RNA-seq and quantitative RT-PCR. The levels of advanced glycation end products (AGEs), IL-1β, and IL-18 in the serum samples and kidney tissues were quantified by ELISA. The levels of collagen IV (COL-4) and fibronectin (FN) expression in kidney tissues were examined by immunohistochemistry and Western blot.

Results

In comparison with the DN group, AS-IV treatment significantly reduced blood glucose levels, food and water consumption, 24 h urine, renal index values, 24 h urine total proteins, blood urea nitrogen (BUN) levels, and creatinine clearance rates (CCR), accompanied by minimizing the DN-induced early kidney damages, fibrosis, and microstructural changes. Furthermore, AS-IV treatment significantly modulated the DN-altered gene transcription profiles in the kidney of rats, particularly for inflammation-related genes, including the nucleotide-binding oligomerization domain-like receptor signaling, which was validated by quantitative RT-PCR. AS-IV treatment significantly decreased the levels of serum and kidney AGEs, IL-1β, and IL-18 expression and fibrosis indexes in the kidney of rats.

Conclusion

AS-IV treatment ameliorated the severity of DN by inhibiting inflammation-related gene expression in the kidney of rats.

Accelerated Kidney Aging in Diabetes Mellitus

With aging, the kidney undergoes inexorable and progressive changes in structural and functional performance. These aging-related alterations are more obvious and serious in diabetes mellitus (DM). Renal accelerated aging under DM conditions is associated with multiple stresses such as accumulation of advanced glycation end products (AGEs), hypertension, oxidative stress, and inflammation. The main hallmarks of cellular senescence in diabetic kidneys include cyclin-dependent kinase inhibitors, telomere shortening, and diabetic nephropathy-associated secretory phenotype. Lysosome-dependent autophagy and antiaging proteins Klotho and Sirt1 play a fundamental role in the accelerated aging of kidneys in DM, among which the autophagy-lysosome system is the convergent mechanism of the multiple antiaging pathways involved in renal aging under DM conditions. Metformin and the inhibitor of sodium-glucose cotransporter 2 are recommended due to their antiaging effects independent of antihyperglycemia, besides angiotensin-converting enzyme inhibitors/angiotensin receptor blockers. Additionally, diet intervention including low protein and low AGEs with antioxidants are suggested for patients with diabetic nephropathy (DN). However, their long-term benefits still need further study. Exploring the interactive relationships among antiaging protein Klotho, Sirt1, and autophagy-lysosome system may provide insight into better satisfying the urgent medical needs of elderly patients with aging-related DN.

Epigenetic Regulation Associated With Sirtuin 1 in Complications of Diabetes Mellitus

Diabetes mellitus (DM) has been one of the largest health concerns of the 21st century due to the serious complications associated with the disease. Therefore, it is essential to investigate the pathogenesis of DM and develop novel strategies to reduce the burden of diabetic complications. Sirtuin 1 (SIRT1), a nicotinamide adenosine dinucleotide (NAD⁺)-dependent deacetylase, has been reported to not only deacetylate histones to modulate chromatin function but also deacetylate numerous transcription factors to regulate the expression of target genes, both positively and negatively. SIRT1 also plays a crucial role in regulating histone and DNA methylation through the recruitment of other nuclear enzymes to the chromatin. Furthermore, SIRT1 has been verified as a direct target of many microRNAs (miRNAs). Recently, numerous studies have explored the key roles of SIRT1 and other related epigenetic mechanisms in diabetic complications. Thus, this review aims to present a summary of the rapidly growing field of epigenetic regulatory mechanisms, as well as the epigenetic influence of SIRT1 on the development and progression of diabetic complications, including cardiomyopathy, nephropathy, and retinopathy.

Mechanisms of Herbal Nephroprotection in diabetes mellitus

Diabetic nephropathy (DN) is a leading cause of kidney morbidity. Despite the multilayered complexity of the mechanisms involved in the pathogenesis of DN, the conventional treatment is limited to just a few drug classes fraught with the risk of adverse events, including the progression of renal dysfunction. Phytoceuticals offer a promising alternative as they act on the many-sidedness of DN pathophysiology, multitargeting its intricacies. This paper offers a review of the mechanisms underlying the protective action of these phytoagents, including boosting the antioxidant capabilities, suppression of inflammation, averting the proliferative and sclerosing/fibrosing events. The pathogenesis of DN is viewed as a continuum going from the original offense, high glucose, through the noxious products it generates (advanced glycation end-products, products of oxidative and nitrosative stress) and the signaling chains consequently brought into action, to the harmful mediators of inflammation, sclerosis, and proliferation that eventually lead to DN, despite the countervailing attempts of the protective mechanisms. Special attention was given to the various pathways involved, pointing out the ability of the phytoagents to hinder the deleterious ones (especially those leading to, driven by, or associated with TGF-β activation, SREBP, Smad, MAPK, PKC, NF-κB, NLRP3 inflammasome, and caspase), to promote the protective ones (PPAR-α, PPAR-γ, EP4/Gs/AC/cAMP, Nrf2, AMPK, and SIRT1), and to favorably modulate those with potentially dual effect (PI3K/Akt). Many phytomedicines have emerged as potentially useful out of in vitro and in vivo studies, but the scarcity of human trials seriously undermines their usage in the current clinical practice-an issue that stringently needs to be addressed.

Irisin alleviates pulmonary epithelial barrier dysfunction in sepsis-induced acute lung injury via activation of AMPK/SIRT1 pathways

OBJECTIVE

Alveolar epithelial barrier dysfunction in response to inflammatory reaction contributes to pulmonary edema in acute lung injury(ALI).Irisin,a newly-found myokine,exerts the anti-inflammatory effects. This study aims to investigate the protective effects of irisin on lipopolysaccharide (LPS)-induced ALIin vivo and in vitro, and to explore its underlying mechanism.

METHODS

Male SD rats and A549 cells were divided into 4 groups: control group, LPS group, Irisin pretreated group, and Irisin/Compound C(a special inhibitor of AMPK)-treated group. The ALI model was established by intravenous injection of LPS in rats, and LPS challenge in A549 cells. Pulmonary specimens were harvested for microscopic examination of the pathological changes, and the expression of AMPK,SIRT1,NF-κB, p66Shc and caspase-3 in lung tissues. The pulmonary permeability were examined by wet/dry lung weight ratio(W/D) and lung permeability index(LPI). The apoptotic index, and the expression of tumor necrosis factor-α(TNF-α), interleukin-1β(IL-1β), monocyte chemoattractant activating protein-1 (MCP-1), tight junctions (occludin,ZO-1) were determined both in lung tissue and A549 cells.

RESULTS

Irisin alleviated lung histological changes and decreased pulmonary microvascular permeability in LPS-induced rats. Irisin up-regulated the expression of occludin, ZO-1,AMPK,SIRT1, down-regulated the expression of TNF-α,IL-1β,MCP-1,NF-κB, p66Shc caspase-3, and decreased the apoptotic index in LPS-induced rats and A549 cells. All these protective effects of irisin could be reversed by Compound C.

CONCLUSION

Irisin improved LPS-induced alveolar epithelial barrier dysfunction via suppressing inflammation and apoptosis, and this protective effect might be mediated by activating AMPK/SIRT1 pathways.

Silent mating-type information regulation 2 homolog 1 overexpression is an important strategy for the survival of adapted suspension tumor cells

Characterization of circulating tumor cells (CTC) is important to prevent death caused by the metastatic spread of cancer cells because CTC are associated with distal metastasis and poor prognosis of breast cancer. We have previously developed suspension cells (SC) using breast cancer cell lines and demonstrated their high metastatic potential. As survival of CTC is highly variable from a few hours to decades, herein we cultured SC for an extended time and named them adapted suspension cells (ASC). Silent mating‐type information regulation 2 homolog 1 (SIRT1) expression increased in ASC, which protected the cells from apoptosis. High SIRT1 expression was responsible for the suppression of nuclear factor kappa B (NF‐κB) activity and downregulation of reactive oxygen species (ROS) in ASC. As the inhibition of NF‐κB and ROS production in SIRT1‐depleted ASC contributed to the development of resistance to apoptotic cell death, maintenance of a low ROS level and NF‐κB activity in ASC is a crucial function of SIRT1. Thus, SIRT1 overexpression may play an important role in growth adaptation of SC because SIRT1 expression is increased in long‐term rather than in short‐term cultures.

Metformin inhibits high glucose-induced mesangial cell proliferation, inflammation and ECM expression through the SIRT1-FOXO1-autophagy axis

The aim of this study was to investigate the role of metformin in high glucose-induced mesangial cell proliferation, inflammation and extracellular matrix (ECM) accumulation and to elucidate the underlying mechanism of metformin function. An MTT assay was used to examine rat mesangial cell (RMC) proliferation. The levels of TNF-α, IL-6 and TGF-β in RMCs were determined by ELISA. The protein expression of fibronectin, collagen IV and autophagy-related proteins (Beclin-1, LC3-I and LC3-II) in RMCs was detected using western blot. Fluorescence microscopy analysis was carried out to evaluate RMC autophagy. Our results showed that high glucose-induced RMC proliferation, inflammation and ECM expression, but these effects were markedly reduced by metformin. We confirmed that metformin suppressed high glucose-induced RMC proliferation, inflammation and ECM expression via induction of autophagy. Mechanistic investigation demonstrated an axis of SIRT1-FOXO1 in RMC autophagy. Our data indicated that metformin inhibits high glucose-induced mesangial cell proliferation, inflammation and ECM expression through a SIRT1-FOXO1-autophagy axis.

The Role of Astragaloside IV against Cerebral Ischemia/Reperfusion Injury: Suppression of Apoptosis via Promotion of P62-LC3-Autophagy

Background: Ischemia/reperfusion (I/R) caused by ischemic stroke treatments leads to brain injury, and autophagy plays a role in the pathology. Astragaloside IV is a potential neuroprotectant, but its underlying mechanism on cerebral I/R injury needs to be explored. The objective of this study is to investigate the neuroprotective mechanism of Astragaloside IV against cerebral I/R injury. Methods: Middle cerebral artery occlusion method (MCAO) and oxygen and glucose deprivation/reoxygenation (OGD/R) method were used to simulate cerebral I/R injury in Sprague-Dawley (SD) rats and HT22 cells, respectively. The neurological score, 2,3,5-Triphe-nyltetrazolium chloride (TTC) staining, and transmission electron microscope were used to detect cerebral damage in SD rats. Cell viability and cytotoxicity assay were tested in vitro. Fluorescent staining and flow cytometry were applied to detect the level of apoptosis. Western blotting was conducted to examine the expression of proteins associated with autophagy. Results: This study found that Astragaloside IV could decrease the neurological score, reduce the infarct volume in the brain, and alleviate cerebral I/R injury in MCAO rats. Astragaloside IV promoted cell viability and balanced Bcl-2 and Bax expression in vitro, reduced the rate of apoptosis, decreased the expression of P62, and increased the expression of LC3II/LC3I in HT22 cells after OGD/R. Conclusions: These data suggested that Astragaloside IV plays a neuroprotective role by down-regulating apoptosis by promoting the degree of autophagy.

P-glycoprotein Inhibitor Tariquidar Potentiates Efficacy of Astragaloside IV in Experimental Autoimmune Encephalomyelitis Mice

ATP-binding cassette (ABC) transporters, such as P-glycoprotein (P-gp) and breast cancer resistance protein (BCRP), often reduce drug efficacy and are the major cause of drug resistance. Astragaloside IV (ASIV), one of the bioactive saponins isolated from Astragalus membranaceus, has been demonstrated to alleviate the progression of experimental autoimmune encephalomyelitis (EAE) in mice, an animal model for multiple sclerosis (MS). In the present study, we found for the first time that ASIV induced the upregulation of P-gp and BCRP in the central nervous system (CNS) microvascular endothelial cells of EAE mice. Further study disclosed that tariquidar, a P-gp inhibitor, could facilitate the penetration of ASIV into CNS. On bEnd.3 cells, a mouse brain microvascular endothelial cell line, tariquidar benefited the net uptake and transport of ASIV. Additional molecular docking experiment suggested that ASIV might be a potential substrate of P-gp. In EAE mice, tariquidar was demonstrated to enhance the efficacy of ASIV, as shown by attenuated clinical symptom and reduced incidence rate as well as mitigated inflammatory infiltration and decreased demyelination in the CNS. Collectively, our findings implicate that P-gp inhibitor can promote the therapeutic efficacy of ASIV on EAE mice, which may boost its clinical usage together with ASIV in the therapy of MS.

Chinese Herbal Medicine in Ameliorating Diabetic Kidney Disease via Activating Autophagy

Diabetic kidney disease (DKD), a leading cause of end-stage renal disease (ESRD), has become a serious public health problem worldwide and lacks effective therapies due to its complex pathogenesis. Recent studies suggested defective autophagy involved in the pathogenesis and progression of DKD. Chinese herbal medicine, as an emerging option for the treatment of DKD, could improve diabetic kidney injury by activating autophagy. In this review, we briefly summarize underlying mechanisms of autophagy dysregulation in DKD, including AMP-activated protein kinase (AMPK), the mechanistic target of rapamycin (mTOR), and the sirtuin (Sirt) pathways, and we particularly concentrate on the current status of Chinese herbal medicine treating DKD by regulating autophagy. The advances in our understanding regarding the treatment of DKD via regulating autophagy with Chinese herbal medicine will enhance the clinical application of Chinese medicine as well as discovery of novel therapeutic agents for diabetic patients.