Curcumin ameliorates diabetic nephropathy by inhibiting the activation of the SphK1-S1P signaling pathway

Cellular and Molecular Mechanisms of Phytochemicals Against Inflammation-Associated Diseases and Viral Infection

Inflammation-associated diseases have become widespread and pose a significant threat to human health, and the therapeutic methods for diverse diseases are inadequate due to the undesirable effects of synthetic ingredients. Recently, more and more evidence indicated that phytochemicals, plant secondary metabolites, have numerous therapeutic functions against human diseases via affecting a variety of mechanisms with their distinct advantages of high efficiency and low toxicity. Here, we highlight the mechanisms of phytochemicals to hinder inflammation-associated diseases (including Inflammatory diseases, cardiovascular diseases, metabolic syndrome, neurological disorders, skin diseases, respiratory diseases, kidney diseases, gastrointestinal diseases, retinal diseases, viral infections) by regulating the crosstalk among various signal cascades (including MicroRNAs, SIRT1, DNMTs, NF-κB, NLRP3, TGF-β, the Gasdermin-mediated pyroptosis pathway), which can be considered as a novel and potential therapeutic strategy. Furthermore, phytochemicals could prevent virus infection by disturbing different targets in the virus replication cycle. However, natural plants have shown limited bioavailability due to their low water solubility, the use of adjuvants such as liposomal phytochemicals, phytochemical nanoparticles and phytochemicals-phospholipid complex promote their bioavailability to exhibit beneficial effects against various diseases. The purpose of this review is to explore the molecular mechanisms and promising applications of phytochemicals in the fields of inflammation-associated diseases and virus infection to provide some direction.

Potential Role of Indian Spices in the Management of Diabetic Complication: A Pre-Clinical and Clinical Review

Diabetic is a metabolic disorder that is concerning for people worldwide, caused by a lack of insulin or ineffective production of insulin in the pancreas. Diabetic retinopathy, nephropathy, and neuropathy are significant microvascular complications of diabetes mellitus, contributing to substantial morbidity and mortality worldwide. Several synthetic medications have been developed. However, none of the compounds provides complete recovery. Long-term use of some synthetic medications might have serious negative effects, thus, there is a need for safe, affordable, and effective medications. Throughout human history, traditional ailments have been much respected as a source of treatment. Their widespread usage across the globe suggests that herbs/ spices are becoming an increasingly important component of cutting-edge, contemporary medications. Therefore, the objective of this review is mainly based on the beneficial effect of Indian spices in managing diabetes. We review the current primary and clinical evidence about the potential of Indian spices, including curcumin, ginger, coriander, cumin seed, garlic, clove, cinnamon, curry leaves, and fenugreek seed with mainly their hypoglycemic and antioxidant properties, for treating diabetes mellitus, also managing diabetic-associated complications, such as neuropathy, retinopathy, and nephropathy. Here, we present the pre-clinical and clinical studies demonstrating how these spices can improve glucose metabolism, enhance insulin secretion, and mitigate oxidative stress, potentially alleviating diabetic complications.

Natural Compounds in Kidney Disease: Therapeutic Potential and Drug Development

Diabetic kidney disease (DKD) poses a major global health challenge, affecting millions of individuals and contributing to substantial morbidity and mortality. Traditional treatments have focused primarily on managing symptoms and slowing disease progression rather than reversing or halting kidney damage. However, recent advancements in natural compound research have unveiled promising new avenues for therapeutic development. Extensive research has been conducted to showcase the antioxidant advantages for kidney health, supporting the potential effectiveness of natural and synthetic products in clinical and experimental research. Bioactive substances found in large quantities in food, such as polyphenols, have emerged as adjuvants. This review manuscript aims to provide a comprehensive overview of natural compounds and their potential efficacy, mechanisms of action, and clinical applications in the prevention and treatment of various kidney diseases. This review emphasizes the connection between oxidative stress and inflammation in diabetic nephropathy (DN), which leads to harmful effects on kidney cells due to pathological damage. A lower incidence of DM2-related problems and a slower progression of end-stage renal disease have been associated with the consumption of these compounds.

A Narrative Review of Signaling Pathway and Treatment Options for Diabetic Nephropathy

BACKGROUND

Diabetic nephropathy is a progressive kidney disease that frequently results in end-stage renal disorders and is characterized by proteinuria, albuminuria, decreased filtration, and renal fibrosis. Despite the fact that there are a number of therapeutic alternatives available, DN continues to be the main contributor to end-stage renal disease. Therefore, significant innovation is required to enhance outcomes in DN patients.

METHODS

Information was collected from online search engines like, Google Scholar, Web of Science, PubMed, Scopus, and Sci-Hub databases using keywords like diabetes, nephropathy, kidney disease, autophagy, etc. Results: Natural compounds have anti-inflammatory and antioxidant properties and impact various signaling pathways. They ameliorate kidney damage by decreasing oxidative stress, inflammatory process, and fibrosis and enhance the antioxidant system, most likely by activating and deactivating several signaling pathways. This review focuses on the role of metabolic memory and various signaling pathways involved in the pathogenesis of DN and therapeutic approaches available for the management of DN. Special attention is given to the various pathways modulated by the phytoconstituents.

Repurposing Nano Curcumin: Unveiling its Therapeutic Potential in Diabetic Nephropathy

Currently, Diabetic Nephropathy (DN) stands as the predominant global cause of endstage renal disease. Many scientists believe that diabetes will eventually spread to pandemic levels due to the rising prevalence of the disease. While the primary factor leading to diabetic nephropathy is vascular dysfunction induced by hyperglycemia, several other pathological elements, such as fibrosis, inflammation, and oxidative stress, also contribute to the progression of the disease. The primary targets of current DN therapy approaches are the underlying abnormalities of hypertension and glucose. With several targets and fewer side effects, curcumin is a commonly utilized antioxidant in DN. The present study emphasizes the critical role of oxidative stress and inflammation in the development of diabetic nephropathy. It reveals how these factors induce damage in key kidney cell types, highlighting their potential as therapeutic targets for this disease. In addition, by concentrating on Nrf2, SIRT1, HMGB1, NF-κB, and NLRP3 of curcumin, has strong anti- inflammatory and antioxidant characteristics. This review describes the role of curcumin in the therapeutic application of diabetic nephropathy. In this attempt, we tried to elaborate on the bench-to-bedside aspects of curcumin in DN, including clinical and preclinical investigations. The rationales of curcumin's mechanisms in alleviating symptoms of the DN were discussed. Curcumin could serve as the potential therapeutic agent for the patient seeking to recover from DN.

Role of curcumin on beta-amyloid protein, tau protein, and biochemical and oxidative changes in streptozotocin-induced diabetic rats

Diabetes is one of the most common endocrine metabolic diseases and is associated with the accumulation of beta-amyloid plaques in the brain. Amyloid beta (Aβ) and abnormal tau proteins are effective in the development of Alzheimer's disease. The aim of this study is to investigate the therapeutic and protective effects of curcumin on beta-amyloid (Aβ) accumulation and tau protein expression levels, as well as biochemical and oxidative changes in streptozotocin-induced diabetes in rats. The study comprised five groups, each consisting of eight rats: control, diabetic, curcumin, curcumin during diabetic induction, and curcumin post-diabetic induction. Groups 2 and 4 were administered a single dose of 45 mg/kg streptozotocin on day 1, while group 5 received it on day 28. Curcumin was orally administered via gavage at a dose of 100 mg/kg/day for 35 days to the third, fourth, and fifth groups. At the end of the trial (day 35), blood sugar levels and insulin resistance were similar between the control and curcumin-treated groups but significantly higher in the diabetic groups (P < 0.05). The protective effect of curcumin is tested during induction and active diabetes. The results indicated that diabetic rats displayed increased levels of Aβ, tau protein, and total oxidant capacity (TOS) compared to the curcumin-treated groups. Additionally, the total antioxidant capacity (TAS) levels were lower in the diabetic rats (P < 0.05). Aβ protein levels are lower in both the serum and brain of rats with active diabetes and treated with curcumin compared to control rats (P > 0.05). In addition, serum TAS levels were higher in rats treated with curcumin following the induction of diabetes than pre-induction of diabetes (P > 0.05). The TOS levels in the serum were higher in the rats treated with curcumin during active diabetes compared to the rats treated prior to the induction of diabetes (P < 0.05). However, no significant difference was observed in the brain. The above results show that curcumin has an effect on reducing oxidative stress caused by diabetes and increasing antioxidant activity.

Pleiotropic functions and clinical importance of circulating HDL-PON1 complex

High density lipoprotein (HDL) functions are mostly mediated through a complex proteome, particularly its enzymes. HDL can provide a scaffold for the assembly of several proteins that affect each other's function. HDL particles, particularly small, dense HDL3, are rich in paraoxonase 1 (PON1), which is an important enzyme in the functionality of HDL, so the antioxidant and antiatherogenic properties of HDL are largely attributed to this enzyme. There is an increasing need to represent a valid, reproducible, and reliable method to assay HDL function in routine clinical laboratories. In this context, HDL-associated proteins may be key players; notably PON1 activity (its arylesterase activity) may be a proper candidate because its decreased activity can be considered an important risk factor for HDL dysfunctionality. Of note, automated methods have been developed for the measurement of serum PON1 activity that facilitates its assay in large sample numbers. Arylesterase activity is proposed as a preferred activity among the different activities of PON1 for its assay in epidemiological studies. The binding of PON1 to HDL is critical for the maintenance of its activity and it appears apolipoprotein A-I plays an important role in HDL-PON1 interaction as well as in the biochemical and enzymatic properties of PON1. The interrelationships between HDL, PON1, and HDL's other components are complex and incompletely understood. The purpose of this review is to discuss biochemical and clinical evidence considering the interactions of PON1 with HDL and the role of this enzyme as an appropriate biomarker for HDL function as well as a potential therapeutic target.

To Explore the Putative Molecular Targets of Diabetic Nephropathy and their Inhibition Utilizing Potential Phytocompounds

BACKGROUND

This review critically addresses the putative molecular targets of Diabetic Nephropathy (DN) and screens effective phytocompounds that can be therapeutically beneficial, and highlights their mechanistic modalities of action.

INTRODUCTION

DN has become one of the most prevalent complications of clinical hyperglycemia, with individual-specific variations in the disease spectrum that leads to fatal consequences. Diverse etiologies involving oxidative and nitrosative stress, activation of polyol pathway, inflammasome formation, Extracellular Matrix (ECM) modifications, fibrosis, and change in dynamics of podocyte functional and mesangial cell proliferation adds up to the clinical complexity of DN. Current synthetic therapeutics lacks target-specific approach, and is associated with the development of inevitable residual toxicity and drug resistance. Phytocompounds provides a vast diversity of novel compounds that can become an alternative therapeutic approach to combat the DN.

METHODS

Relevant publications were searched and screened from research databases like GOOGLE SCHOLAR, PUBMED and SCISEARCH. Out of 4895 publications, the most relevant publications were selected and included in this article.

RESULT

This study critically reviews over 60 most promising phytochemical and provides with their molecular targets, that can be of pharmacological significance in context to current treatment and concomitant research in DN.

CONCLUSION

This review highlights those most promising phytocompounds that have the potential of becoming new safer naturally-sourced therapeutic candidates and demands further attention at clinical level.

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.

Clinical Use and Treatment Mechanism of Molecular Hydrogen in the Treatment of Various Kidney Diseases including Diabetic Kidney Disease

As diabetes rates surge globally, there is a corresponding rise in the number of patients suffering from diabetic kidney disease (DKD), a common complication of diabetes. DKD is a significant contributor to chronic kidney disease, often leading to end-stage renal failure. However, the effectiveness of current medical treatments for DKD leaves much to be desired. Molecular hydrogen (H2) is an antioxidant that selectively reduces hydroxyl radicals, a reactive oxygen species with a very potent oxidative capacity. Recent studies have demonstrated that H2 not only possesses antioxidant properties but also exhibits anti-inflammatory effects, regulates cell lethality, and modulates signal transduction. Consequently, it is now being utilized in clinical applications. Many factors contribute to the onset and progression of DKD, with mitochondrial dysfunction, oxidative stress, and inflammation being strongly implicated. Recent preclinical and clinical trials reported that substances with antioxidant properties may slow the progression of DKD. Hence, we undertook a comprehensive review of the literature focusing on animal models and human clinical trials where H2 demonstrated effectiveness against a variety of renal diseases. The collective evidence from this literature review, along with our previous findings, suggests that H2 may have therapeutic benefits for patients with DKD by enhancing mitochondrial function. To substantiate these findings, future large-scale clinical studies are needed.

Curcumin-Loaded Bamboo Shoot Cellulose Nanofibers: Characterization and In Vitro Studies

Given its high biological and pharmacological activities, curcumin (CUR) offers promising applications in functional foods. However, its low stability and bioavailability have greatly hindered its application in the food industry. The present study prepared cellulose nanofiber (CNF) from bamboo shoot processing byproducts and investigated its potential as a low-cost carrier. Our results showed that CUR was immobilized on CNF surfaces mainly through hydrogen bonding and eventually encapsulated in CNF matrices, forming a CNF-CUR complex with an encapsulation efficiency of 88.34% and a loading capacity of 67.95%. The CUR encapsulated in the complex showed improved stability after thermal and UV light treatments. Moreover, a slow and extended release pattern of CUR in a simulated gastrointestinal tract was observed, which could be appropriately described using the Korsmeyer-Peppas model. These results revealed that CNF is a promising protective carrier for the slow release of CUR, making it a better candidate for functional foods.

Activating Protein-1 (AP-1): A Promising Target for the Treatment of Fibrotic Diseases

The fibrosis of tissues and organs occurs via an aberrant tissue remodeling process characterized by an excessive deposition of extracellular matrix, which can lead to organ dysfunction, organ failure, and death. Because the pathogenesis of fibrosis remains unclear and elusive, there is currently no medication to reverse it; hence, this process deserves further study. Activating protein-1 (AP-1)-comprising Jun (c-Jun, JunB, JunD), Fos (c-fos, FosB, Fra1, and Fra2), and activating transcription factor-is a versatile dimeric transcription factor. Numerous studies have demonstrated that AP-1 plays a crucial role in advancing tissue and organ fibrosis via induction of the expression of fibrotic molecules and activating fibroblasts. This review focuses on the role of AP-1 in a range of fibrotic disorders as well as on the antifibrotic effects of AP-1 inhibitors. It also discusses the potential of AP-1 as a new therapeutic target in conditions involving tissue and organ fibrosis.

Nanocurcumin combined with insulin alleviates diabetic kidney disease through P38/P53 signaling axis

Treatments for diabetic kidney disease (DKD) mainly focus on managing hyperglycemia and hypertension, but emerging evidence suggests that inflammation also plays a role in the pathogenesis of DKD. This 10-week study evaluated the efficacy of daily oral nanoparticulate-curcumin (nCUR) together with long-acting insulin (INS) to treat DKD in a rodent model. Diabetic rats were dosed with unformulated CUR alone, nCUR alone or together with INS, or INS alone. The progression of diabetes was reflected by increases in plasma fructosamine, blood urea nitrogen, creatinine, bilirubin, ALP, and decrease in albumin and globulins. These aberrancies were remedied by nCUR+INS or INS but not by CUR or nCUR. Kidney histopathological results revealed additional abnormalities characteristic of DKD, such as basement membrane thickening, tubular atrophy, and podocyte cytoskeletal impairment. nCUR and nCUR+INS mitigated these lesions, while CUR and INS alone were far less effective, if not ineffective. To elucidate how our treatments modulated inflammatory signaling in the liver and kidney, we identified hyperactivation of P38 (MAPK) and P53 with INS and CUR, whereas nCUR and nCUR+INS deactivated both targets. Similarly, the latter interventions led to significant downregulation of renal NLRP3, IL-1β, NF-ĸB, Casp3, and MAPK8 mRNA, indicating a normalization of inflammasome and apoptotic pathways. Thus, we show therapies that reduce both hyperglycemia and inflammation may offer better management of diabetes and its complications.

Oxidative Stress and NRF2/KEAP1/ARE Pathway in Diabetic Kidney Disease (DKD): New Perspectives

Diabetes mellitus (DM) is one of the most debilitating chronic diseases worldwide, with increased prevalence and incidence. In addition to its macrovascular damage, through its microvascular complications, such as Diabetic Kidney Disease (DKD), DM further compounds the quality of life of these patients. Considering DKD is the main cause of end-stage renal disease (ESRD) in developed countries, extensive research is currently investigating the matrix of DKD pathophysiology. Hyperglycemia, inflammation and oxidative stress (OS) are the main mechanisms behind this disease. By generating pro-inflammatory factors (e.g., IL-1,6,18, TNF-α, TGF-β, NF-κB, MCP-1, VCAM-1, ICAM-1) and the activation of diverse pathways (e.g., PKC, ROCK, AGE/RAGE, JAK-STAT), they promote a pro-oxidant state with impairment of the antioxidant system (NRF2/KEAP1/ARE pathway) and, finally, alterations in the renal filtration unit. Hitherto, a wide spectrum of pre-clinical and clinical studies shows the beneficial use of NRF2-inducing strategies, such as NRF2 activators (e.g., Bardoxolone methyl, Curcumin, Sulforaphane and their analogues), and other natural compounds with antioxidant properties in DKD treatment. However, limitations regarding the lack of larger clinical trials, solubility or delivery hamper their implementation for clinical use. Therefore, in this review, we will discuss DKD mechanisms, especially oxidative stress (OS) and NRF2/KEAP1/ARE involvement, while highlighting the potential of therapeutic approaches that target DKD via OS.

An update on molecular mechanisms of curcumin effect on diabetes

Owing to its prevalent nature, diabetes mellitus has become one of the most serious endocrine illnesses affecting a patient's quality of life due to the manifestation of side effects such as cardiovascular diseases, retinopathy, neuropathy, and nephropathy. Curcumin ((1E, 6E) 21, 7-bis (4-hydroxy-3-methoxyphenyl)-1,6-heptadiene-3,5-dione), a major compound of turmeric, has been used in conventional medicine because of its safe nature and cost-effectiveness to meliorate diabetes and its comorbidities. These effects have also been observed in rodent models of diabetes resulting in a reduction of glycemia and blood lipids. Both the preventive and therapeutic activities of this compound are due to its antioxidant and anti-inflammatory characteristics. Furthermore, preclinical outcomes and clinical investigation demonstrate that the use of curcumin neutralizes insulin resistance, obesity, and hyperglycemia. Despite the many benefits of curcumin, its two limiting factors, solubility and bioavailability, remain a challenge for researchers; therefore, several methods such as drug formulation, nano-drug delivery, and the use of curcumin analogs have been developed to deliver curcumin and increase its bioavailability. PRACTICAL APPLICATIONS: The rise of people with type 2 diabetes has become a major concern at the global healthcare level. The best diabetes treatments today are anti-diabetic drug administration, lifestyle-related interventions (such as healthy eating and daily physical activity), arterial pressure detection, and fat control. The polyphenol curcumin, found in turmeric, can promote health by acting on a variety of cellular signaling pathways. This review article discusses curcumin and its role in the treatment of diabetes.

A Novel Identified Circular RNA, mmu_mmu_circRNA_0000309, Involves in Germacrone-Mediated Improvement of Diabetic Nephropathy Through Regulating Ferroptosis by Targeting miR-188-3p/GPX4 Signaling Axis

Aims: Diabetic nephropathy (DN) is characterized by microalbuminuria, mainly associated with pathological and morphological alterations of podocyte. New drug targeting podocyte injury is a promising approach for treating DN. The present study is aimed at developing new drug targeting podocyte injury for treating DN. Results: In this study, germacrone ameliorated kidney damage and inhibited podocyte apoptosis in a DN mouse model. Based on RNA-seq, mmu_mmu_circRNA_0000309, located in host gene vascular endothelial zinc finger 1 (Vezf1), showed a sharp decline in DN mice and a remarkable recovery in germacrone-challenged DN mice. mmu_circRNA_0000309 silence or miR-188-3p mimics abrogated the antiapoptosis and anti-injury effects of germacrone through aggravating mitochondria damage, and elevating reactive oxygen species and ferroptosis-related protein levels. Mechanistically, mmu_circRNA_0000309 competitively sponged miR-188-3p, and subsequently promoted glutathione peroxidase 4 (GPX4) expression, thereby inactivating ferroptosis-dependent mitochondrial damage and podocyte apoptosis. In addition, GPX4 overexpression neutralized mmu_circRNA_0000309 silence-mediated mitochondria damage and ferroptosis in germacrone-exposed MPC5 cells. Innovation: We describe the novel effect and mechanism of germacrone on treating DN, which is linked to ferroptosis for the first time. Conclusion: mmu_circRNA_0000309 silence mediates drug resistance to germacrone in DN mice. mmu_circRNA_0000309 sponges miR-188-3p, and subsequently upregulates GPX4 expression, inactivating ferroptosis-dependent mitochondrial function and podocyte apoptosis. Possibly germacrone-based treatment for DN can be further motivated by regulating mmu_circRNA_0000309/miR-188-3p/GPX4 signaling axis. Antioxid. Redox Signal. 36, 740-759.

Bisacurone attenuates diabetic nephropathy by ameliorating oxidative stress, inflammation and apoptosis in rats

BACKGROUND

Diabetes nephropathy (DN) is a serious diabetic problem that may progress to renal failure. The root of Curcuma longa L., often known as turmeric, provides various health benefits. Bisacurone is a bioactive terpenoid found in small amounts in turmeric that possesses anti-inflammatory and antioxidant properties. The present study focuses on the potential protective effects of bisacurone against DN via reducing renal inflammation, oxidative stress, and apoptosis.

METHODS

Type 2 diabetes was created in rats by feeding them a high-fat/high-sugar diet for 8 weeks, followed by a low dose of streptozotocin and Bisacurone (50 and 100 μg/kg bisacurone) given for 4 weeks.

RESULTS

In diabetic rats, bisacurone reduced hyperglycemia, protected against body weight (BW) loss, lowered renal markers, reduced lipid profile alterations and avoided histological abnormalities. Bisacurone treatment reduced oxidative stress by decreasing malondialdehyde (MDA) levels while enhancing antioxidant defenses through superoxide dismutase (SOD), catalase (CAT), and glutathione peroxidase (GPx) levels. Furthermore, bisacurone treatment activated the renal Nrf2/Keap1 signaling pathway but attenuated the high levels of NFκB p65, TNF-α, IL-1β, IL-6, Cox2, and iNOS. Bisacurone also reduced Bax, caspase-3, caspase-9 and cytochrome c but increased Bcl-2 in the kidneys of diabetic rats.

CONCLUSION

In the present study, bisacurone reduces DN by reducing hyperglycemia, oxidative stress, inflammation, and apoptosis, while also increasing Nrf2/HO-1 signaling.

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.

Overview of key molecular and pharmacological targets for diabetes and associated diseases

Diabetes epidemiological quantities are demonstrating one of the most important communities' health worries. The essential diabetic difficulties are including cardiomyopathy, nephropathy, inflammation, and retinopathy. Despite developments in glucose decreasing treatments and drugs, these diabetic complications are still ineffectively reversed or prohibited. Several signaling and molecular pathways are vital targets in the new therapies of diabetes. This review assesses the newest researches about the key molecules and signaling pathways as targets of molecular pharmacology in diabetes and diseases related to it for better treatment based on molecular sciences. The disease is not cured by current pharmacological strategies for type 2 diabetes. While several drug combinations are accessible that can efficiently modulate glycemia and mitigate long-term complications, these agents do not reverse pathogenesis, and in practice, they are not established to modify the patient's specific molecular profiling. Therapeutic companies have benefited from human genetics. Genome exploration, which is agnostic to the information that exists, has revealed tens of loci that impact glycemic modulation. The physiological report has begun to examine subtypes of diseases, illustrate heterogeneity and propose biochemical therapeutic pathways.

Tumor necrosis factor superfamily 14 is critical for the development of renal fibrosis

Objective: Tumor necrosis factor superfamily protein 14 (TNFSF14) was recently identified as a risk factor in some fibrosis diseases. However, the role of TNFSF14 in renal fibrosis pathogenesis remains unknown.

Results: It was found that TNFSF14 levels were significantly increased both in UUO-induced renal fibrotic mice and in patients with fibrotic nephropathy, compared with those in controls. Accordingly, Tnfsf14 deficiency led to a marked reduction in renal fibrosis lesions and inflammatory cytokines expression in the UUO mice. Furthermore, the levels of Sphk1, a critical molecule that causes fibrotic nephropathy, were remarkably reduced in Tnfsf14 KO mice with UUO surgery. In vitro recombinant TNFSF14 administration markedly up-regulated the expression of Sphk1 of primary mouse renal tubular epithelial cells (mTECs).

Conclusion: TNFSF14 is a novel pro-fibrotic factor of renal fibrosis, for which TNFSF14 up-regulates Sphk1 expression, which may be the underlying mechanism of TNFSF14-mediated renal fibrosis.

Methods: We investigated the effect of TNFSF14 on renal fibrosis and the relationship between TNFSF14 and pro-fibrotic factor sphingosine kinase 1 (Sphk1) by using the unilateral urethral obstruction (UUO)-induced mice renal fibrosis as a model and the specimen of patients with fibrosis nephropathy, by Masson trichrome staining, immunohistochemistry, qRT-PCR, and western blot analysis.

Therapeutic application of nutraceuticals in diabetic nephropathy: Current evidence and future implications

Diabetes mellitus (DM) is a common metabolic disease which may cause several complications, such as diabetic nephropathy (DN). The routine medical treatments used for DM are not effective enough and have many undesirable side effects. Moreover, the global increased prevalence of DM makes researchers try to explore potential complementary or alternative treatments. Nutraceuticals, as natural products with pharmaceutical agents, have a wide range of therapeutic properties in various pathologic conditions such as DN. However, the exact underlying mechanisms have not been fully understood. The purpose of this review is to summarize recent findings on the effect of nutraceuticals on DN.

Investigation on the Metabolism of Curcumin and Baicalein in Zebrafish by Liquid Chromatography-tandem Mass Spectrometry Analysis

Background:

Curcumin (CUR) and baicalein (BAI) are the main active ingredients in Curcuma longa and Scutellaria baicalensis, which are used together in Jiang-Qin-Si-Wu decoction to treat gynecological diseases. On the other hand, zebrafish, as a metabolic model has become more popular, therefore, the metabolism of CUR and BAI in zebrafish is investigated in the present study.

Methods:

Zebrafish embryos after hatching 48 hours were divided into four experimental groups. The blank group was exposed to 1 mL of ultra-pure water. Three drug-treated groups were exposed to CUR (8 μM, 1 mL), BAI (8 μM, 1 mL), CUR and BAI (8 μM, 2 mL), respectively. After homogenization, they were analyzed by liquid chromatography-tandem mass spectrometry (LCMS/ MS). The structure of the metabolites was determined by comparing their corresponding mass spectra with those of relevant literature. According to the change of metabolite content, the metabolic effect of curcumin and baicalein was explored.

Results:

Five and six metabolites of CUR and BAI in zebrafish were identified by LC-MS/MS, respectively. Their metabolic pathways in zebrafish were glucuronidation and sulfation. Reduction and methylation reactions also occurred for CUR and BAI, respectively. In addition, after combined exposure of both the drugs, CUR reduced the BAI glucuronide metabolites and inhibited the metabolism of BAI in zebrafish, which is consistent with the mammalian metabolism.

Conclusion:

Using LC-MS/MS analysis, zebrafish is a feasible model for drug metabolism study. The results of metabolic study indicated that CUR might affect the therapeutic effect of BAI.

Erythrocyte Metabolic Reprogramming by Sphingosine 1-Phosphate in Chronic Kidney Disease and Therapies

RATIONALE

Hypoxia promotes renal damage and progression of chronic kidney disease (CKD). The erythrocyte is the only cell type for oxygen (O₂) delivery. Sphingosine 1-phosphate (S1P)-a highly enriched biolipid in erythrocytes-is recently reported to be induced under high altitude in normal humans to enhance O₂ delivery. However, nothing is known about erythrocyte S1P in CKD.

OBJECTIVE

To investigate the function and metabolic basis of erythrocyte S1P in CKD with a goal to explore potential therapeutics.

METHODS AND RESULTS

Using erythrocyte-specific SphK1 (sphingosine kinase 1; the only enzyme to produce S1P in erythrocytes) knockout mice (eSphK1^-/-) in an experimental model of hypertensive CKD with Ang II (angiotensin II) infusion, we found severe renal hypoxia, hypertension, proteinuria, and fibrosis in Ang II-infused eSphk1^-/- mice compared with controls. Untargeted metabolomics profiling and in vivo U-¹³C₆ isotopically labeled glucose flux analysis revealed that SphK1 is required for channeling glucose metabolism toward glycolysis versus pentose phosphate pathway, resulting in enhanced erythroid-specific Rapoport-Luebering shunt in Ang II-infused mice. Mechanistically, increased erythrocyte S1P functioning intracellularly activates AMPK (AMP-activated protein kinase) 1α and BPGM (bisphosphoglycerate mutase) by reducing ceramide/S1P ratio and inhibiting PP2A (protein phosphatase 2A), leading to increased 2,3-bisphosphoglycerate (an erythrocyte-specific metabolite negatively regulating Hb [hemoglobin]-O₂-binding affinity) production and thus more O₂ delivery to counteract kidney hypoxia and progression to CKD. Preclinical studies revealed that an AMPK agonist or a PP2A inhibitor rescued the severe CKD phenotype in Ang II-infused eSphK1^-/- mice and prevented development of CKD in the control mice by inducing 2,3-bisphosphoglycerate production and thus enhancing renal oxygenation. Translational research validated mouse findings in erythrocytes of hypertensive CKD patients and cultured human erythrocytes.

CONCLUSIONS

Our study elucidates the beneficial role of eSphk1-S1P in hypertensive CKD by channeling glucose metabolism toward Rapoport-Luebering shunt and inducing 2,3-bisphosphoglycerate production and O₂ delivery via a PP2A-AMPK1α signaling pathway. These findings reveal the metabolic and molecular basis of erythrocyte S1P in CKD and new therapeutic avenues.

Bioactive compounds from the seeds of Amomum tsaoko Crevost et Lemaire, a Chinese spice as inhibitors of sphingosine kinases, SPHK1/2

Amomum tsaoko Crevost et Lemaire (Zingiberaceae), a traditional Chinese spice also known as “Caoguo” or “tsao-ko,” has been considered to have many health benefits. As part of our continuous efforts to screen natural resources exhibiting potential bioactivity, we examined the seeds of A. tsaoko and found that its EtOH extract inhibited sphingosine kinases 1 and 2 (SPHK1/2). Bioactivity-based analysis and chemical investigation of the EtOH extract led to the isolation and identification of four aliphatic alcohols (1–4), five fatty acids (5–9), 12 phenolics (10–21), and four terpenoids (22–25), including four new compounds, an acetylated aliphatic alcohol (2), a fatty acid (5), and two phenolics (10–11). In addition, compound 1 was isolated for the first time from natural sources in this study. The structures of all compounds were elucidated based on spectroscopic analysis, including 1D and/or 2D NMR and HR-ESIMS as well as LC/MS analysis. A recently developed method using competing enantioselective acylation (CEA) coupled with LC/MS analysis was applied for the assignment of absolute configuration of compound 5. The absolute configurations of compounds 10 and 11 were determined using ECD calculations. All of the compounds (1–25) isolated from the active fraction were evaluated for their SPHK1/2 inhibitory effects at the concentration of 10 μM. Aliphatic alcohols 2–4, fatty acids 7 and 9, and phenolic compounds 13–15 and 21 showed inhibition against the activity of SPHK1 up to 20% and aliphatic alcohols 2 and 4, fatty acid 8, and phenolic compounds 10, 11, 18, and 22 showed inhibition against the activity of SPHK2 up to 40% compared with the control. Compound 2 showed the highest potency to inhibit SPHK1 enzymatic activity, by 59.75%, and compound 22 showed the highest potency in inhibiting the activity of SPHK2, by 22.75%, in comparison with the control, where both exhibited higher inhibition compared to those of positive controls. Docking modeling studies were conducted to suggest the binding mode of 2 and 22 in the substrate-binding pocket of SPHK1 and SPHK2, respectively.

New bioactive compounds were identified from the seeds of Amomum tsaoko Crevost et Lemaire, a Chinese spice as inhibitors of sphingosine kinases, SPHK1/2.

Amelioration of diabetic nephropathy in db/db mice treated with tibetan medicine formula Siwei Jianghuang Decoction Powder extract

Siwei Jianghuang Decoction Powder (SWJH) documented originally in the Four Medical Tantras-Blue Glaze exhibited beneficial effects on diabetic nephropathy (DN) via combined synergistically action of multiple formula components including Curcumae longae Rhizoma, Berberidis dictyophyllae Cortex, Phyllanthi Fructus and Tribuli Fructus. This study investigated the effects of SWJH on DN in db/db mice and possible underlying mechanisms. The ten weeks old db/db mice treated with SWJH by intra-gastric administration once a day for 8 weeks. After 8 weeks, body weight, water and food intake of mice were recorded. The level of fasting blood glucose (FBG) was measured. Serum creatinine (Scr), blood urea nitrogen (BUN), urine microalbumin (UMAlb), serum uric acid (UA) and urinary albumin excretion (UAE) were detected. An enzyme-linked immunosorbent assay was performed to test serum vascular endothelial growth factor (VEGF) and transforming growth factor-β1 (TGF-β1). Real-time PCR and Western blot analysis were used to test mRNA and protein expression of hypoxia inducible factor-1α (HIF-1α), VEGF and TGF-β1 in kidney tissue. SWJH treatment significantly reduced the levels of FBG, Scr, BUN, UMAlb, UA and UAE and retarded renal fibrosis. SWJH treatment further significantly reduced serum TGF-β1 level and downregulated the expression of HIF-1α, VEGF and TGF-β1 at both mRNA and protein levels. Principal component analysis and partial least squares regression and hierarchical cluster analysis demonstrated that SWJH treatment significantly ameliorated renal damage in DN mice. These consequences suggested that SWJH formulations were effective in the treatment of DN through regulating the HIF-1α, VEGF and TGF-β1 overexpression.

Activation of Nrf2 signaling by natural products-can it alleviate diabetes?

Type 2 diabetes mellitus (DM) has reached pandemic proportions and effective prevention strategies are wanted. Its onset is accompanied by cellular distress, the nuclear factor erythroid 2-related factor 2 (Nrf2) is a transcription factor boosting cytoprotective responses, and many phytochemicals activate Nrf2 signaling. Thus, Nrf2 activation by natural products could presumably alleviate DM. We summarize function, regulation and exogenous activation of Nrf2, as well as diabetes-linked and Nrf2-susceptible forms of cellular stress. The reported amelioration of insulin resistance, β-cell dysfunction and diabetic complications by activated Nrf2 as well as the status quo of Nrf2 in precision medicine for DM are reviewed.

Lentivirus-mediated siRNA knockdown of SPHK1 inhibits proliferation and tumorigenesis of neuroblastoma

BACKGROUND

The overexpression of sphingosine kinase 1 (SPHK1) is responsible for the progress of many cancers. However, the role of SPHK1 in the development and progression of neuroblastoma (NB) remain largely unknown. Here in this study, we explored whether silencing SPHK1 by lentivirus-mediated siRNA could be employed as a potential therapeutic target for NB.

MATERIALS AND METHODS

Lentivirus was adopted to load SPHK1 siRNA. The results were obtained using RT-qPCR, Western blot, cell proliferation assay, transwell cell migration/invasion assays as well as in vivo xenograft tumor models in nude mice.

RESULTS

Our results demonstrated that SPHK1 mRNA was upregulated in SH-SY5Y and SK-N-SH cells as well as in human NB tissues. SPHK1 knockdown by siRNA resulted in impaired proliferation, increased apoptosis, as well as impaired migration and invasion of SH-SY5Y and SK-N-SH cells. In addition, the in vivo study suggested that SPHK1 knockdown significantly reduced the tumorigenesis of SH-SY5Y xenograft model. Furthermore, intratumorally administered lentivirus-SPHK1 siRNA could significantly inhibit tumor growth in an SH-SY5Y xenograft mice model. Intensive investigations on mechanism revealed that these effects were achieved through the deactivation of STAT3 pathways.

CONCLUSION

These data suggest that SPHK1 inhibition via downregulation of STAT3 pathways by lentivirus-mediated siRNA knockdown can significantly suppress NB progression, which could be a promising target for future gene therapy of NB.

Spice-Derived Bioactive Ingredients: Potential Agents or Food Adjuvant in the Management of Diabetes Mellitus

Spices possess tremendous therapeutic potential including hypoglycemic action, attributed to their bioactive ingredients. However, there is no study that critically reviewed the hypoglycemic potency, safety and the bioavailability of the spice-derived bioactive ingredients (SDBI). Therefore, the aim of the study was to comprehensively review all published studies regarding the hypoglycemic action of SDBI with the purpose to assess whether the ingredients are potential hypoglycemic agents or adjuvant. Factors considered were concentration/dosages used, the extent of blood glucose reduction, the IC50 values, and the safety concern of the SDBI. From the results, cinnamaldehyde, curcumin, diosgenin, thymoquinone (TQ), and trigonelline were showed the most promising effects and hold future potential as hypoglycemic agents. Conclusively, future studies should focus on improving the tissue and cellular bioavailability of the promising SDBI to achieve greater potency. Additionally, clinical trials and toxicity studies are with these SDBI are warranted.

Sphingolipid signaling in renal fibrosis

Over the last decade, various sphingolipid subspecies have gained increasing attention as important signaling molecules that regulate a multitude of physiological and pathophysiological processes including inflammation and tissue remodeling. These mediators include ceramide, sphingosine 1-phosphate (S1P), the cerebroside glucosylceramide, lactosylceramide, and the gangliosides GM3 and Gb3. These lipids have been shown to accumulate in various chronic kidney diseases that typically end in renal fibrosis and ultimately renal failure. This review will summarize the effects and contributions of those enzymes that regulate the generation and interconversion of these lipids, notably the acid sphingomyelinase, the acid sphingomyelinase-like protein SMPDL3B, the sphingosine kinases, the S1P lyase, the glucosylceramide synthase, the GM3 synthase, and the α-galactosidase A, to renal fibrotic diseases. Strategies of manipulating these enzymes for therapeutic purposes and the impact of existing drugs on renal pathologies will be discussed.

Sphingosine 1-Phosphate Signaling as a Target in Hepatic Fibrosis Therapy

Liver fibrosis is an excess production of extracellular matrix proteins as a result of chronic liver disease which leads to cell death and organ dysfunction. The key cells involved in fibrogenesis are resident hepatic stellate cells (HSCs) which are termed myofibroblasts after activation, acquiring contractile, proliferative, migratory and secretory capability. Sphingosine 1-phosphate (S1P) is a bioactive sphingolipid with well-established effects on angiogenesis, carcinogenesis and immunity. Accumulating evidence demonstrates that this metabolite is involved in the profibrotic inflammatory process through the regulation of pleiotropic cell responses, such as vascular permeability, leukocyte infiltration, cell survival, migration, proliferation and HSCs differentiation to myofibroblasts. S1P is synthesized by sphingosine kinases (SphKs) and many of its actions are mediated by S1P specific cell surface receptors (S1P_1-5), although different intracellular targets of S1P have been identified. Modulation of SphKs/S1P/S1P receptors signaling is known to result in beneficial effects on various in vivo and in vitro models of liver fibrosis. Thus, a better knowledge of the molecular mechanisms involved in the modulation of the S1P pathway could help to improve liver fibrosis therapy. In this review, we analyze the effects of the S1P axis on the fibrogenic process, and the involvement of a range of inhibitors or approaches targeting enzymes related to S1P in the abrogation of pathological fibrogenesis. All in all, targeting this pathway offers therapeutic potential in the treatment of hepatic fibrosis.

Recent Advances of Curcumin in the Prevention and Treatment of Renal Fibrosis

Curcumin, a polyphenol derived from the turmeric, has received attention as a potential treatment for renal fibrosis primarily because it is a relatively safe and inexpensive compound that contributes to kidney health. Here, we review the literatures on the applications of curcumin in resolving renal fibrosis in animal models and summarize the mechanisms of curcumin and its analogs (C66 and (1E,4E)-1,5-bis(2-bromophenyl) penta-1,4-dien-3-one(B06)) in preventing inflammatory molecules release and reducing the deposition of extracellular matrix at the priming and activation stage of renal fibrosis in animal models by consulting PubMed and Cnki databases over the past 15 years. Curcumin exerts antifibrotic effect through reducing inflammation related factors (MCP-1, NF-κB, TNF-α, IL-1β, COX-2, and cav-1) and inducing the expression of anti-inflammation factors (HO-1, M6PRBP1, and NEDD4) as well as targeting TGF-β/Smads, MAPK/ERK, and PPAR-γ pathways in animal models. As a food derived compound, curcumin is becoming a promising drug candidate for improving renal health.

Inhibition of the SphK1/S1P signaling pathway by melatonin in mice with liver fibrosis and human hepatic stellate cells

The sphingosine kinase 1/sphingosine 1-phosphate (SphK1/S1P) system is involved in different pathological processes, including fibrogenesis. Melatonin abrogates activation of hepatic stellate cells (HSCs) and attenuates different profibrogenic pathways in animal models of fibrosis, but it is unknown if protection associates with its inhibitory effect on the SphK1/S1P axis. Mice in treatment groups received carbon tetrachloride (CCl4 ) 5 μL g-1 body wt i.p. twice a week for 4 or 6 weeks. Melatonin was given at 5 or 10 mg kg-1  day-1 i.p, beginning 2 weeks after the start of CCl4 administration. At both 4 and 6 weeks following CCl4 treatment, liver mRNA levels, protein concentration and immunohistochemical labelling for SphK1 increased significantly. S1P production, and expression of S1P receptor (S1PR)1, S1PR3 and acid sphingomyelinase (ASMase) were significantly elevated. However, there was a decreased expression of S1PR2 and S1P lyase (S1PL). Melatonin attenuated liver fibrosis, as shown by a significant inhibition of the expression of α-smooth muscle actin (α-SMA), transforming growth factor (TGF)-β and collagen (Col) Ι. Furthermore, melatonin inhibited S1P production, lowered expression of SphK1, S1PR1, SP1R3, and ASMase, and increased expression of S1PL. Melatonin induced a reversal of activated human HSCs cell line LX2, as evidenced by a reduction in α-SMA, TGF-β, and Col I expression. Melatonin-treated cells also exhibited an inhibition of the SphK1/S1P axis. Antifibrogenic effect of SphK1 inhibition was confirmed by treatment of LX2 cells with PF543. Abrogation of the lipid signaling pathway by the indole reveals novel molecular pathways that may account for the protective effect of melatonin in liver fibrogenesis. © 2016 BioFactors, 43(2):272-282, 2017.

Network Pharmacology Studies on the Bioactive Compounds and Action Mechanisms of Natural Products for the Treatment of Diabetes Mellitus: A Review

Diabetes mellitus (DM) is a kind of chronic and metabolic disease, which can cause a number of diseases and severe complications. Network pharmacology approach is introduced to study DM, which can combine the drugs, target proteins and disease and form drug-target-disease networks. Network pharmacology has been widely used in the studies of the bioactive compounds and action mechanisms of natural products for the treatment of DM due to the multi-components, multi-targets, and lower side effects. This review provides a balanced and comprehensive summary on network pharmacology from current studies, highlighting different bioactive constituents, related databases and applications in the investigations on the treatment of DM especially type 2. The mechanisms related to type 2 DM, including α-amylase and α-glucosidase inhibitory, targeting β cell dysfunction, AMPK signal pathway and PI3K/Akt signal pathway are summarized and critiqued. It suggests that the network pharmacology approach cannot only provide a new research paradigm for natural products, but also improve the current antidiabetic drug discovery strategies. Furthermore, we put forward the perspectives on the reasonable applications of network pharmacology for the therapy of DM and related drug discovery.

Effects of curcumin in experimental diabetic nephropathy

Diabetic nephropathy (DN) is currently well established as the most common cause of end-stage renal disease in most parts of the world. Notwithstanding the expanding basic and clinical research in this field, the pathogenesis remains far from clear and hence the treatment of DN remains suboptimal. There is a critical need for the development of newer therapeutic strategies including alternative and complementary therapies. One of the natural products that was extensively studied in cancer and other chronic disease states such as diabetes is curcumin, an active ingredient in turmeric, a spice extensively used in India. In this manuscript, we present a critical review of the experimental and clinical evidence that supports the use of curcumin and its analogs in DN as well as the various proposed mechanisms for its biological actions in health and disease states.

C66 ameliorates diabetic nephropathy in mice by both upregulating NRF2 function via increase in miR-200a and inhibiting miR-21

AIMS/HYPOTHESIS

Diabetic nephropathy is the leading cause of end-stage renal disease. Previously we reported that C66, a novel analogue of curcumin with a very high bioavailability, ameliorated diabetic nephropathy in mice, with little known about the mechanism. The present study aimed to define the mechanism by which C66 ameliorates diabetic nephropathy.

METHODS

Our aim was to discover whether C66 acts through the activation of nuclear factor (erythroid-derived 2)-like 2 (NFE2L2 or NRF2), which governs the antioxidant response. Streptozotocin-induced Nrf2 (also known as Nfe2l2)-knockout and wild-type (WT) diabetic mice were treated with C66. To determine whether the actions of C66 on NRF2 are mediated by microRNA (miR)-200a, WT diabetic mice were treated with C66 in the presence or absence of an in vivo miR-200a inhibitor (locked nucleic acid-modified anti-miR-200a [LNA-200a]) for 6 months. To determine whether miR-21 downregulation provided an NRF2-independent basis for C66 protection, Nrf2-knockout diabetic mice were treated with either C66 or an inhibitor of miR-21 (locked nucleic acid-modified anti-miR-21 [LNA-21]).

RESULTS

Deletion of Nrf2 partially abolished diabetic nephropathy protection by C66, confirming the requirement of NRF2 for this protection. Diabetic mice, but not C66-treated diabetic mice, developed significant albuminuria, renal oxidative damage and fibrosis. C66 upregulated renal miR-200a, inhibited kelch-like ECH-associated protein 1 and induced NRF2 function, effects that were prevented by LNA-200a. However, LNA-200a only partially reduced the protection afforded by C66, suggesting the existence of miR-200a/NRF2-independent mechanisms for C66 protection. C66 was also found to inhibit diabetes induction of miR-21. Both C66 and LNA-21 produced similar reductions in miR-21, albuminuria and renal fibrosis.

CONCLUSIONS/INTERPRETATION

The present study indicates that in addition to upregulating NRF2 by increasing miR-200a, C66 also protects against diabetic nephropathy by inhibiting miR-21.

Polydatin attenuates AGEs-induced upregulation of fibronectin and ICAM-1 in rat glomerular mesangial cells and db/db diabetic mice kidneys by inhibiting the activation of the SphK1-S1P signaling pathway

We previously demonstrated that activation of sphingosine kinase 1 (SphK1)- sphingosine 1- phosphate (S1P) signaling pathway by high glucose (HG) plays a pivotal role in increasing the expression of fibronectin (FN), an important fibrotic component, by promoting the DNA-binding activity of transcription factor activator protein 1 (AP-1) in glomerular mesangial cells (GMCs) under diabetic conditions. As a multi-target anti-oxidative drug, polydatin (PD) has been shown to have renoprotective effects on experimental diabetes. However, whether PD could resist diabetic nephropathy (DN) by regulating SphK1-S1P signaling pathway needs further investigation. Here, we found that PD significantly reversed the upregulated FN and ICAM-1 expression in GMCs exposed to AGEs. Simultaneously, PD dose-dependently inhibited SphK1 levels at the protein expression and kinase activity and attenuated S1P production under AGEs treatment conditions. In addition, PD reduced SphK activity in GMCs transfected with wild-type SphK(WT) plasmid and significantly suppressed SphK1-mediated increase of FN and ICAM-1 levels under normal conditions. Furthermore, we found that the AGEs-induced upregulation of phosphorylation of c-Jun at Ser63 and Ser73 and c-Fos at Ser32, DNA-binding activity and transcriptional activity of AP-1 were blocked by PD. In comparison with db/db model group, PD treatment suppressed SphK1 levels (mRNA, protein expression, and activity) and S1P production, reversed the upregulation of FN, ICAM-1, c-Jun, and c-Fos in the kidney tissues of diabetic mice, and finally ameliorated renal injury in db/db mice. These findings suggested that the downregulation of SphK1-S1P signaling pathway is probably a novel mechanism by which PD suppressed AGEs-induced FN and ICAM-1 expression and improved renal dysfunction of diabetic models.

Protective Effects of Curcumin on Renal Oxidative Stress and Lipid Metabolism in a Rat Model of Type 2 Diabetic Nephropathy

PURPOSE

Diabetic nephropathy is a serious complication of type 2 diabetes mellitus, and delaying the development of diabetic nephropathy in patients with diabetes mellitus is very important. In this study, we investigated inflammation, oxidative stress, and lipid metabolism to assess whether curcumin ameliorates diabetic nephropathy.

MATERIALS AND METHODS

Animals were divided into three groups: Long-Evans-Tokushima-Otsuka rats for normal controls, Otsuka-Long-Evans-Tokushima Fatty (OLETF) rats for the diabetic group, and curcumin-treated (100 mg/kg/day) OLETF rats. We measured body and epididymal fat weights, and examined plasma glucose, adiponectin, and lipid profiles at 45 weeks. To confirm renal damage, we measured albumin-creatinine ratio, superoxide dismutase (SOD), and malondialdehyde (MDA) in urine samples. Glomerular basement membrane thickness and slit pore density were evaluated in the renal cortex tissue of rats. Furthermore, we conducted adenosine monophosphate-activated protein kinase (AMPK) signaling and oxidative stress-related nuclear factor (erythroid-derived 2)-like 2 (Nrf2) signaling to investigate mechanisms of lipotoxicity in kidneys.

RESULTS

Curcumin ameliorated albuminuria, pathophysiologic changes on the glomerulus, urinary MDA, and urinary SOD related with elevated Nrf2 signaling, as well as serum lipid-related index and ectopic lipid accumulation through activation of AMPK signaling.

CONCLUSION

Collectively, these findings indicate that curcumin exerts renoprotective effects by inhibiting renal lipid accumulation and oxidative stress through AMPK and Nrf2 signaling pathway.

Essential Roles of RNA-binding Protein HuR in Activation of Hepatic Stellate Cells Induced by Transforming Growth Factor-β1

RNA-binding protein HuR mediates transforming growth factor (TGF)-β1-induced profibrogenic actions. Up-regulation of Sphingosine kinase 1 (SphK1) is involved in TGF-β1-induced activation of hepatic stellate cells (HSCs) in liver fibrogenesis. However, the molecular mechanism of TGF-β1 regulates SphK1 remains unclear. This study was designed to investigate the role of HuR in TGF-β1-induced SphK1 expression and identify a new molecular mechanism in liver fibrogenensis. In vivo, HuR expression was increased, translocated to cytoplasm, and bound to SphK1 mRNA in carbon tetrachloride- and bile duct ligation-induced mouse fibrotic liver. HuR mRNA expression had a positive correlation with mRNA expressions of SphK1 and fibrotic markers, α-smooth muscle actin (α-SMA) and Collagen α1(I), respectively. In vitro, up-regulation of SphK1 and activation of HSCs stimulated by TGF-β1 depended on HuR cytoplasmic accumulation. The effects of TGF-β1 were diminished when HuR was silenced or HuR cytoplasmic translocation was blocked. Meanwhile, overexpression of HuR mimicked the effects of TGF-β1. Furthermore, TGF-β1 prolonged half-life of SphK1 mRNA by promoting its binding to HuR. Pharmacological or siRNA-induced SphK1 inhibition abrogated HuR-mediated HSC activation. In conclusion, our data suggested that HuR bound to SphK1 mRNA and played a crucial role in TGF-β1-induced HSC activation.

Curcumin Suppresses Phthalate-Induced Metastasis and the Proportion of Cancer Stem Cell (CSC)-like Cells via the Inhibition of AhR/ERK/SK1 Signaling in Hepatocellular Carcinoma

Recent evidence indicating that phthalates promote cancer development, including cell proliferation, migration, and invasion, has raised public health concerns. Here, we show that bis(2-ethylhexyl) phthalate promotes the migration, invasion, and epithelial-mesenchymal transition of hepatocellular carcinoma cells. In addition, bis(2-ethylhexyl) phthalate increased the proportion of cancer stem cell (CSC)-like cells and stemness maintenance in vitro as well as tumor growth and metastasis in vivo. The various activities of curcumin, including anticancer, anti-inflammation, antioxidation, and immunomodulation, have been investigated extensively. Curcumin suppressed phthalate-induced cell migration, invasion, and epithelial-mesenchymal transition, decreased the proportion of CSC-like cells in hepatocellular carcinoma cell lines in vitro, and inhibited tumor growth and metastasis in vivo. We also reveal that curcumin suppressed phthalate-induced migration, invasion, and CSC-like cell maintenance through inhibition of the aryl hydrocarbon receptor/ERK/SK1/S1P3 signaling pathway. Our results suggest that curcumin may be a potential antidote for phthalate-induced cancer progression.

Effects of curcumin and captopril on the functions of kidney and nerve in streptozotocin-induced diabetic rats: role of angiotensin converting enzyme 1

Oxidative stress and inflammation are involved in the development and progression of diabetes and its complications. The renin-angiotensin system also plays an important role in the pathogenesis of diabetes and its complications. We hypothesized that curcumin and captopril would restore the kidney and nerve functions of diabetic rats through their angiotensin converting enzyme 1 (ACE1) inhibiting activity as well as their antioxidant and anti-inflammatory effects. Diabetes was induced by a single intraperitoneal injection of streptozotocin (100 mg·kg(-1) body weight). One week after induction of diabetes, rats were treated with 100 mg·kg(-1)·day(-1) curcumin or 50 mg·kg(-1)·day(-1) captopril orally for 6 weeks. Compared with diabetic control rats, curcumin- or captopril-treated diabetic rats had significantly improved blood glucose, lipid profile, kidney/body weight ratio, serum creatinine, blood urea nitrogen (BUN), and pain thresholds assessed by Von Frey filaments, hot plate test, and tail-flick test. Diabetic control rats showed increased levels of total peroxide, renal and neural tumor necrosis factor-α and interleukin-10, and renal ACE1 compared with nondiabetic rats. Although treatment with either curcumin or captopril restored the altered variables, captopril was more effective in reducing these variables. ACE1 was positively correlated with BUN and creatinine and negatively correlated with paw withdrawal threshold, hot plate reaction time, and tail-flick latency, suggesting a possible causal relationship. We conclude that curcumin and captopril protect against diabetic nephropathy and neuropathy by inhibiting ACE1 as well as oxidation and inflammation. These findings suggest that curcumin and captopril may have a role in the treatment of diabetic nephropathy and neuropathy.

Diabetic nephropathy research in China: Data analysis and review from the National Natural Science Foundation of China

As the largest funding agency of natural science of China, the National Natural Science Foundation of China (NSFC) has made great efforts in promoting the development of diabetic nephropathy (DN) research in recent years. The aim of the current study is to summarize the diabetic nephropathy research in China by analyzing NSFC-funded projects. Data on all projects in the DN field funded by NSFC from 1986 to 2013 were collected. The funding tendency, funding areas, and hotspots in the DN field, and major research institutions, were analyzed. As one output of this support, outstanding research groups in China, and their representative studies, are also highlighted. From 1986 to 2013, the NSFC has funded a total of 248 projects in the DN field, with a total funding amount of 91.5 million RMB (US$14.9 million). A rapid increase could be seen in the past 5 years, with an average annual 30% increase in projects numbers and a 52% increase in funding amount. All fields in DN research have been covered by the NSFC, including etiology, pathophysiology, diagnostics, and therapeutics. Along with increased funding of the DN research, there has been a growth in the papers published in Science Citation Index journals by Chinese scholars. In the past decade, the funding scale and funding budget have increased dramatically. Benefiting from this, DN research in China has also made considerable progression.