Preventive effects and mechanisms of rhein on renal interstitial fibrosis in obstructive nephropathy

Rhein: An Updated Review Concerning Its Biological Activity, Pharmacokinetics, Structure Optimization, and Future Pharmaceutical Applications

Rhein is a natural active ingredient in traditional Chinese medicine that has attracted much attention due to its wide range of pharmacological activities. However, its clinical application is limited by low water solubility, poor oral absorption, and potential toxicity to the liver and kidneys. Recently, advanced extraction and synthesis techniques have made it possible to develop derivatives of rhein, which have better pharmacological properties and lower toxicity. This article comprehensively summarizes the biological activity and action mechanism of rhein. Notably, we found that TGF-β1 is the target of rhein improving tissue fibrosis, while NF-κB is the main target of its anti-inflammatory effect. Additionally, we reviewed the current research status of the pharmacokinetics, toxicology, structural optimization, and potential drug applications of rhein and found that the coupling and combination therapy of rhein and other active ingredients exhibit a synergistic effect, significantly enhancing therapeutic efficacy. Finally, we emphasize the necessity of further studying rhein's pharmacological mechanisms, toxicology, and development of analogs, aiming to lay the foundation for its widespread clinical application as a natural product and elucidate its prospects in modern medicine.

Recent Advances in Biologically Active Ingredients from Natural Drugs for Sepsis Treatment

Sepsis refers to the dysregulated host response to infection; its incidence and mortality rates are high. It is a worldwide medical problem but there is no specific drug for it. In recent years, clinical and experimental studies have found that many monomer components of traditional Chinese medicine have certain effects on the treatment of sepsis. This paper reviews the advances in research on the active ingredients of traditional Chinese medicine involved in the treatment of sepsis in recent years according to their chemical structure; it could provide ideas and references for further research and development in Chinese materia medica for the treatment of sepsis.

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.

Comparative pharmacokinetics of six bioactive components of Shen-Wu-Yi-Shen tablets in normal and chronic renal failure rats based on UPLC-TSQ-MS/MS

ETHNOPHARMACOLOGICAL RELEVANCE

Shen-Wu-Yi-Shen tablets (SWYST), a Chinese patent medicine consisting of 12 herbal medicines, was formulated by a famous TCM nephrologist, Zou Yunxiang. It is clinically used to improve the symptoms of nausea, vomiting, poor appetite, dry mouth and throat, and dry stool in patients with chronic renal failure (CRF) accompanied by qi and yin deficiency, dampness, and turbidity. SWYST can reduce urea nitrogen, blood creatinine, and urinary protein loss, and increase the endogenous creatinine clearance rate. However, little is known about its pharmacokinetics.

AIM OF STUDY

To compare the pharmacokinetics of six bioactive components after oral administration of SWYST in normal and adenine-induced CRF rats.

MATERIALS AND METHODS

A method based on ultra-performance liquid chromatography coupled with a triple-stage quadrupole mass spectrometer (UPLC-TSQ-MS/MS) was developed and validated to determine the six bioactive compounds (albiflorin, paeoniflorin, plantagoguanidinic acid, rhein, aloe-emodin, and emodin) in rat plasma. Rat plasma samples were prepared using protein precipitation. Chromatography was performed on an Agilent Eclipse Plus C18 column (3.0 × 50 mm, 1.8 μm) using gradient elution with a mobile phase composed of acetonitrile and water containing 0.1% (v/v) formic acid, while detection was achieved by electrospray ionization MS under the multiple selective reaction monitoring modes. After SWYST administration, rat plasma was collected at different time points, and the pharmacokinetic parameters of six analytes were calculated and analyzed based on the measured plasma concentrations.

RESULTS

The UPLC-TSQ-MS/MS method was fully validated for its satisfactory linearity (r ≥ 0.9913), good precisions (RSD <11.5%), and accuracy (RE: -13.4∼13.1%), as well as acceptable limits in the extraction recoveries, matrix effects, and stability (RSD <15%). In normal rats, the six analytes were rapidly absorbed (Tmax ≤ 2 h), and approximately 80% of their total exposure was eliminated within 10 h. Moreover, in normal rats, the AUC0-t and Cmax of albiflorin, plantagoguanidinic acid, and rhein exhibited linear pharmacokinetics within the dose ranges, while that of paeoniflorin is non-linear. However, in CRF rats, the six analytes exhibited reduced elimination and significantly different AUC or Cmax values. These changes may reflect a decreased renal clearance rate or inhibition of drug-metabolizing enzymes and transporters in the liver and gastrointestinal tract caused by CRF.

CONCLUSIONS

A sensitive UPLC-TSQ-MS/MS method was validated and used to investigate the pharmacokinetics of SWYST in normal and CRF rats. This is the first study to investigate the pharmacokinetics of SWYST, and our findings elucidate the causes of their different pharmacokinetic behaviors in CRF rats. Furthermore, the results provide useful information to guide further research on the pharmacokinetic-pharmacodynamic correlation and clinical application of SWYST.

Research Progress on the Positive and Negative Regulatory Effects of Rhein on the Kidney: A Review of Its Molecular Targets

Currently, both acute kidney injury (AKI) and chronic kidney disease (CKD) are considered to be the leading public health problems with gradually increasing incidence rates around the world. Rhein is a monomeric component of anthraquinone isolated from rhubarb, a traditional Chinese medicine. It has anti-inflammation, anti-oxidation, anti-apoptosis, anti-bacterial and other pharmacological activities, as well as a renal protective effects. Rhein exerts its nephroprotective effects mainly through decreasing hypoglycemic and hypolipidemic, playing anti-inflammatory, antioxidant and anti-fibrotic effects and regulating drug-transporters. However, the latest studies show that rhein also has potential kidney toxicity in case of large dosages and long use times. The present review highlights rhein's molecular targets and its different effects on the kidney based on the available literature and clarifies that rhein regulates the function of the kidney in a positive and negative way. It will be helpful to conduct further studies on how to make full use of rhein in the kidney and to avoid kidney damage so as to make it an effective kidney protection drug.

The progress and prospect of natural components in rhubarb (Rheum ribes L.) in the treatment of renal fibrosis

Background: Renal fibrosis is a key pathological change that occurs in the progression of almost all chronic kidney diseases . CKD has the characteristics of high morbidity and mortality. Its prevalence is increasing each year on a global scale, which seriously affects people’s health and quality of life. Natural products have been used for new drug development and disease treatment for many years. The abundant natural products in R. ribes L. can intervene in the process of renal fibrosis in different ways and have considerable therapeutic prospects.

Purpose: The etiology and pathology of renal fibrosis were analyzed, and the different ways in which the natural components of R. ribes L. can intervene and provide curative effects on the process of renal fibrosis were summarized. Methods: Electronic databases, such as PubMed, Life Science, MEDLINE, and Web of Science, were searched using the keywords ‘R. ribes L.’, ‘kidney fibrosis’, ‘emodin’ and ‘rhein’, and the various ways in which the natural ingredients protect against renal fibrosis were collected and sorted out.

Results: We analyzed several factors that play a leading role in the pathogenesis of renal fibrosis, such as the mechanism of the TGF-β/Smad and Wnt/β-catenin signaling pathways. Additionally, we reviewed the progress of the treatment of renal fibrosis with natural components in R. ribes L. and the intervention mechanism of the crucial therapeutic targets.

Conclusion: The natural components of R. ribes L. have a wide range of intervention effects on renal fibrosis targets, which provides new ideas for the development of new anti-kidney fibrosis drugs.

Rhein induces changes in the lysosomal compartment of HeLa cells

Rhein is an anthraquinone found in Rheum palmatum, used in Chinese medicine. Due to potential anticancer properties, the study assessed its effect on the lysosomal compartment, which indirectly influences cell death. The experiment was performed on HeLa cells by treating them with rhein at concentrations of 100-300 µM. LC3-II protein and caspase 3/7 activity, level of apoptosis, the concentration of reactive oxide species (ROS), and mitochondrial potential (Δψm) were evaluated by the cytometric method. To evaluate the permeability of the lysosomal membrane (LMP), staining with acridine orange and the assessment of activity of cathepsin D and L in the lysosomal and extralysosomal fractions were used. Cell viability was assessed by -(3-(4,5-Dimethylthiazol-2-yl)-2,5-Diphenyltetrazolium Bromide) (MTT) and neutral red (NR) assays. Changes in cells were also demonstrated at the level of electron, optical, confocal, and fluorescence microscopy. Inhibition of autophagy was done using chloroquine. Rhein-induced degradation processes were confirmed by an increase in the number of primary lysosomes, autophagosomes, and autolysosomes. At high concentrations, rhein caused the generation of ROS, which induced LMP expressed by quenching of acridine orange fluorescence. These results correlated with a reduction of lysosomes, as visualized in graphical modeling, with the decreased uptake of NR by lysosomes, and increased activity of cathepsin D and L in the extralysosomal fraction. The studies also showed an increase in the activity of caspase 3/7 and a decrease in the expression of Bcl-2 protein, indicative of rhein-stimulated apoptosis. At the same time, we demonstrated that preincubation of cells with chloroquine inhibited rhein-induced autophagy and contributed to increased cytotoxicity to HeLa cells. Rhein also induced DNA damage and led to cycle arrest in the S phase. Our results indicate that rhein, by inducing changes in the lysosomal compartment, indirectly affects apoptosis of HeLa cells and in combination with autophagy inhibitors may be an effective form of anticancer therapy.

Protective effect of Rhein against vancomycin-induced nephrotoxicity through regulating renal transporters and Nrf2 pathway

Vancomycin (VCM)'s nephrotoxicity limits its application and therapeutic efficiency. The aim of this study was to determine the protective effect of rhein against VCM-induced nephrotoxicity (VIN). VIN models were established in rats and NRK-52E cells. Rhein up-regulated the expressions of renal organic anion transporter (Oat) 1, Oat3, organic cation transporter 2 (Oct2), multidrug resistance-associated protein 2 (Mrp2), mammal multidrug and toxin extrusion proteins 1 (Mate 1) and P-glycoprotein (P-gp) to facilitate the efflux of plasma creatinine, blood urea nitrogen (BUN), and plasma indoxyl sulfate. Rhein increased the expression of nuclear factor erythroid 2-related factor 2 (Nrf2) to regulate the expression of Mrp2, P-gp, and Mate 1. The increased level of superoxide dismutase (SOD), decreased level of malondialdehyde (MDA) and reduced number of apoptosis cells were observed after treatment of rhein. Rhein decreased the number of apoptosis cells as well as increased the expression of B-cell lymphoma-2 (Bcl-2) and decreased expressions of Bcl-2-like protein 4 (Bax). ML385, as a typical inhibitor of Nrf2, reversed the protective effects of rhein in cells. Rhein oriented itself in the site of Keap1, inhibiting the Keap1-Nrf2 interaction. Rhein ameliorated VIN mainly through regulating the expressions of renal transporters and acting on Nrf2 pathway.

Rhein Inhibits NF-κB Signaling Pathway to Alleviate Inflammatory Response and Oxidative Stress of Rats with Chronic Glomerulonephritis

Objective

To explore the effect and mechanism of rhein on chronic glomerulonephritis (CGN).

Method

Twenty-four eight-week-old male SD rats were randomly divided into following 4 groups (6 rats in each group): control group, CGN group, rhein group, and benazepril (Ben) group. And 5 mg/mL of cationization-bovine serum albumin (C-BSA) was mixed with an equal volume of Freund's incomplete adjuvant for the preparation of 2.5 mg/mL of C-BSA solution. The rat model of CGN was established by injection of C-BSA for six weeks. Calculation of the renal index in rats was conducted. Biochemical detection was performed to measure the level of 24 h urinary protein, blood urea nitrogen (BUN), serum creatinine (SCr), and serum albumin (ALB) of the rats, as well as the level of malondiadehyde (MDA), superoxide (SOD), and glutathione peroxidase (GSH-Px) in the kidney tissue. Hematoxylin and eosin (H&E) staining was utilized to measure histological changes in the kidney of the rats. The level of TNF-α, IL-1β, IL-6, and ICAM-1 in rat kidney tissues was determined by enzyme-linked immunosorbent assay (ELISA). Western blot was applied to check the expression of NF-κB in the nucleus and cytoplasm as well as the expression of IκBα and p-IκBα in rat kidney tissues.

Results

Rhein could decline urinary protein, restore blood biochemical parameters, and protect renal tissue in rats with CGN. Besides, rhein could inhibit the activity of the NF-κB signaling pathway in rats with CGN and could alleviate the inflammatory response and oxidative stress level at the same time.

Conclusion

Rhein alleviates inflammatory responses and oxidative stress in rats with CGN. It also provides a theoretical basis and data support for the therapeutic drugs for CGN.

Rhein Improves Renal Fibrosis by Restoring Cpt1a-Mediated Fatty Acid Oxidation through SirT1/STAT3/twist1 Pathway

The latest progress in the field of renal fibrosis mainly focuses on the new concept of “partial epithelial-mesenchymal transition (pEMT)” to explain the contribution of renal tubular epithelial (RTE) cells to renal fibrosis and the crucial role of fatty acid oxidation (FAO) dysfunction in RTE cells for the development of renal fibrosis. FAO depression is considered to be secondary or occur simultaneously with pEMT. We explored the relationship between pEMT and FAO and the effect of rhein on them. Intragastric administration of rhein significantly improved the levels of BUN, Scr, α-SMA, collagen 1A and histopathological changes in UUO-rats. Transcriptomic and metabolomic analyses revealed that abnormal signaling pathways were involved in EMT and FAO disorders. RTE cell experiments showed that TGF-β could inhibit the activity of Cpt1a, resulting in ATP depletion and lipid deposition. Cpt1a inhibitor induced EMT, while Cpt1 substrate or rhein inhibited EMT, indicating that Cpt1a-mediated FAO dysfunction is essential for RTE cells EMT. Further studies showed that Cpt1a activity were regulated by SirT1/STAT3/Twist1 pathway. Rhein inhibits RTE cell EMT by promoting Cpt1a-mediated FAO through the SirT1/STAT3/Twist1 pathway. Surprisingly and importantly, our experiments showed that FAO depression occurs before EMT, and EMT is one of the results of FAO depression.

Therapeutic and delivery strategies of phytoconstituents for renal fibrosis

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

Update on Pharmacological Activities, Security, and Pharmacokinetics of Rhein

Rhein, belonging to anthraquinone compounds, is one of the main active components of rhubarb and Polygonum multiflorum. Rhein has a variety of pharmacological effects, such as cardiocerebral protective effect, hepatoprotective effect, nephroprotective effect, anti-inflammation effect, antitumor effect, antidiabetic effect, and others. The mechanism is interrelated and complex, referring to NF-κB, PI3K/Akt/MAPK, p53, mitochondrial-mediated signaling pathway, oxidative stress signaling pathway, and so on. However, to some extent, its clinical application is limited by its poor water solubility and low bioavailability. Even more, rhein has potential liver and kidney toxicity. Therefore, in this paper, the pharmacological effects of rhein and its mechanism, pharmacokinetics, and safety studies were reviewed, in order to provide reference for the development and application of rhein.

Natural product therapies in chronic kidney diseases: An update

Chronic kidney disease is one of the major worldwide public health problems. Traditional Chinese medications have been widely used for chronic kidney disease treatment. As the development of modern phytochemistry technology, natural products have been isolated from traditional Chinese medications, which provide a more precise method for the investigation of traditional Chinese medications. In this article, we selected eight natural products from traditional Chinese medications for chronic kidney disease therapy to summarize the recent advances for the development of new medications.

Deoxycholic acid-functionalised nanoparticles for oral delivery of rhein

Rhein (RH) is a candidate for the treatment of kidney diseases. However, clinical application of RH is impeded by low aqueous solubility and oral bioavailability. Deoxycholic acid-conjugated nanoparticles (DNPs) were prepared by ionic interaction for enhancing intestinal absorption by targeting the apical sodium-dependent bile acid transporter in the small intestine. Resultant DNPs showed relatively high entrapment efficiency (90.7 ± 0.73)% and drug-loading efficiency (6.5 ± 0.29)% with a particle size of approximately 190 nm and good overall dispersibility. In vitro release of RH from DNPs exhibited sustained and pH-dependent profiles. Cellular uptake and apparent permeability coefficient (P_app) of the DNPs were 3.25- and 5.05-fold higher than that of RH suspensions, respectively. An in vivo pharmacokinetic study demonstrated significantly enhanced oral bioavailability of RH when encapsulated in DNPs, with 2.40- and 3.33-fold higher C_max and AUC_0-inf compared to RH suspensions, respectively. DNPs are promising delivery platforms for poorly absorbed drugs by oral administration.

Astragalus-Saffron-Rhubarb Mixture Delays the Progress of Diabetic Nephropathy in db/db Mice

OBJECTIVE

This study aimed to investigate the protective effect of astragalus-saffron-rhubarb mixture (Bao'shen recipe, BSR) on diabetic nephropathy (DN) in db/db mice and preliminarily explore the possible underlying mechanism.

METHODS

A total of 125 8-week-old male db/db mice with DN were randomly divided into five groups: model group, irbesartan group and high-, medium- and low doses of BSR group, while 25 male db/m mice were used as a blank control. At 8, 12, 16, 20, and 24 weeks of feeding, the animals were sacrificed and blood as well as urine samples were collected for blood glucose, urea nitrogen, creatinine and urinary albumin excretion rate (UAER) measurement via blood glucose meter or corresponding detection kits, respectively. The renal tissues of each mouse underwent hematoxylin and eosin (H&E), Masson, periodic acid Schiff (PAS) staining. Renal homogenate was used to detect IL-6, TNF-α, TNF-1R and TNF-2R by enzyme-linked immunosorbent assay. Additionally, the data obtained was statistically analyzed via one-way analysis of variance.

RESULTS

BSR could effectively reduce the body weight, blood glucose, UAER, blood urea nitrogen and creatinine levels, relieve the proliferation of mesangial tissue, and lower the levels of IL-6, TNF-α, TNF-1R, and TNF-2R in renal tissue of db/db mice with DN. Of note, the high-dose BSR treatment group has advantages over irbesartan treatment group in improving above-mentioned aspects.

CONCLUSION

BSR could effectively delay the progress of DN, partly related to its anti-inflammation effect.

Pharmacokinetics and Pharmacodynamics of the Combination of Rhein and Curcumin in the Treatment of Chronic Kidney Disease in Rats

Objectives: The interaction between the components of traditional Chinese medicine (TCM) is an important basis for their synergy. Rhein and curcumin exert various pharmacological activities, including anti-tumour, anti-inflammatory, antioxidant, anti-fibrosis and renoprotective effects. However, no investigation has reported the synergistic anti-fibrosis effect yet. This study aims at determine the pharmacokinetics and pharmacodynamics of the combination of rhein and curcumin in the treatment for chronic kidney disease in rats.

Design: Fifty two male Sprague-Dawley (SD) rats were randomly divided into rhein group, curcumin group and their combination group for pharmacodynamics studies. HE and Masson staining was conducted to observe the changes of renal morphology. Kits were used to detect the level of urea nitrogen (BUN) and creatinine (Scr). For pharmacokinetic study, 36 SD rats were randomly divided into rhein group, curcumin group and a combination group, the content of rhein and curcumin in plasma and renal tissue was determined by ultra-performance liquid chromatography-tandem mass spectrometry (UPLC-MS/MS). In additon, molecular docking method and cell experiments was used to disclose the interaction mechanism between curcumin and rhein.

Results: The pharmacodynamic results showed that the degree of renal fibrosis was improved obviously by co-administration rhein and curcumin. Meanwhile, compared to single administration, the Cmax and AUC of rhein and curcumin in plasma and renal tissue were enhanced significantly after co-administration. Moreover, the result of molecular docking and cell experiments showed that both two compounds could interact with P-gp, CYP2C9 and CYP2C19.

Conclusion: Together, these findings demonstrated that rhein and curcumin had a synergistic effect in ameliorateing chonic kidney disease, providing an important explanation on the synergistic mechanism of curcumin and rhein from a pharmacokinetic viewpoint.

Effects of Rhein on Bile Acid Homeostasis in Rats

Rhein, the active ingredient of rhubarb, a medicinal and edible plant, is widely used in clinical practice. However, the effects of repeated intake of rhein on liver function and bile acid metabolism are rarely reported. In this work, we investigated the alterations of 14 bile acids and hepatic transporters after rats were administered with rhein for 5 weeks. There was no obvious injury to the liver and kidney, and there were no significant changes in biochemical indicators. However, 1,000 mg/kg rhein increased the liver total bile acid (TBA) levels, especially taurine-conjugated bile acids (t-CBAs), inhibited the expression of farnesoid X receptor (FXR), small heterodimer partner (SHP), and bile salt export pump (BSEP) mRNA, and upregulated the expression of (cholesterol 7α-hydroxylase) CYP7A1 mRNA. Rhein close to the clinical dose (10 mg/kg and 30 mg/kg) reduced the amounts of TBAs, especially unconjugated bile acids (UCBAs), and elevated the expression of FXR and multidrug resistance-associated protein 3 (Mrp3) mRNA. These results denote that rhein is relatively safe to use at a reasonable dose and timing. 30 mg/kg rhein may promote bile acid transport and reduce bile acid accumulation by upregulating the expression of FXR mRNA and Mrp3 mRNA, potentially resulting in the decrease in serum UBCAs.

Quantitative and network pharmacology: A case study of rhein alleviating pathological progress of renal interstitial fibrosis

ETHNOPHARMACOLOGICAL RELEVANCE

The current network pharmacology model focuses mainly on static and qualitative characterisation between drugs and targets or molecular pathway networks, but it does not reflect the multi-scale, dynamic and quantitative process of drug action.

AIM OF THE STUDY

In this study, we developed a new model known as quantitative and network pharmacology (QNP) to characterise the dynamic and quantitative interventions of drugs within a multi-scale biological network.

MATERIALS AND METHODS

Firstly, we used a systems biology method to construct a molecule-cell dynamic network model to simulate the pathological processes of diseases. Secondly, according to the principles of enzymatic kinetics, we generated a multi-scale drug intervention model to simulate the intervention of drugs in multi-scale networks at different concentrations and pathological stages. Finally, we took rhein treatment of renal interstitial fibrosis (RIF) as an example to illustrate the QNP model.

RESULTS

We successfully constructed the a QNP model that includes both a multi-scale dynamic network disease model and drug intervention model. The QNP model accurately simulated the pathological process of RIF, and the simulation results were validated by a series of cell and animal experiments. Meanwhile, the QNP model demonstrated that rhein can delay the pathological process at the studied concentrations of 5 nM, 10 nM, and 20 nM, and can also exert a better therapeutic effect on fibrosis before the proliferation stage of RIF. Furthermore, through uncertainty and sensitivity analysis, we identified that FAK and Smad3 may be potential targets for RIF.

CONCLUSION

Our QNP model provides a molecular-cellular understanding of the pathological mechanisms of RIF, serving as a new approach and strategy for the construction of dynamic multi-scale network model of diseases and drug intervention.

Functional Metabolomics Analysis Elucidating the Metabolic Biomarker and Key Pathway Change Associated With the Chronic Glomerulonephritis and Revealing Action Mechanism of Rhein

Chronic glomerulonephritis (CGN) as the culprit of kidney failure can increase the mortality of critically ill patients and seriously threatens people’s health all over the world. This study using metabolomics strategy is to reveal the potential therapeutic mechanism-related targets to evaluate the effects of rhein (RH) on CGN rats. Changes of serum metabolites and pathways were analyzed by non-targeted metabolomic method based on liquid chromatography-mass spectrometry (LC-MS) combined with ingenuity pathway analysis. In addition, the levels of biochemical indicators were also detected. A total of 25 potential biomarkers were identified to express serum metabolic turbulence in CGN animal model, and then 16 biomarkers were regulated by RH trending to the normal states. From metabolite enrichment and pathway analysis, pharmacological activity of RH on CGN were mainly involved in six vital metabolic pathways including phenylalanine, tyrosine and tryptophan biosynthesis, phenylalanine metabolism, arachidonic acid metabolism, tricarboxylic acid cycle (TCA cycle), alanine, aspartate, and glutamate metabolism, arginine and proline metabolism. It suggested CGN treatment with RH, which may be mediated via interference with metabolic pathway such as amino acid metabolism, arachidonic acid metabolism, and TCA cycle to regulating inflammation, oxidation response and immune regulation against CGN. It showed that metabolomics method offer deeply insight into the therapeutic mechanisms of natural product.

A review on the efficacy and mechanism of action of Shenkang injection against chronic kidney disease

Chronic kidney disease (CKD) is one of the most common conditions which significantly increases the risk for serious health outcomes. Epidemiological investigations have shown that CKD has become a serious global health problem. At present, there are no treatments for CKD, thus the need for an effective and safe treatment for this condition. Shenkang Injection (SKI), which is an herbal medication in Chinese Medicine, has been used in the management and treatment of CKD and has achieved favorable therapeutic effects. The purpose of this paper is to review the clinical efficacy, mechanism of action, and safety profile of SKI when used in CKD, and to provide comprehensive potential evidence for its clinical application.

Renal protection of rhein against 5/6 nephrectomied-induced chronic kidney disease: role of SIRT3-FOXO3α signalling pathway

OBJECTIVES

The purpose of this study is to investigate the antifibrosis and anti-oxidation of rhein in vivo and in vitro, and to evaluate potential mechanisms involved in the treatment of chronic kidney disease (CKD).

METHODS

In experimental animal studies, CKD was established by 5/6 nephrectomy (5/6Nx). Serum creatinine (Scr) and blood urea nitrogen (BUN) were determined. Histopathologic tests were performed by HE and Masson trichrome stained. The level of ROS was investigated by fluorescence microplate with the probe 2', 7'-dichlorofluorescein diacetate (DCFH-DA). The protein expressions of p47phox and gp91phox were measured in 5/6Nx rats. In HK-2 cells, the expression of SIRT3 and Foxo3α was measured in SIRT3 knockdown conditions. The indicators of oxidation and fibrosisi were measured in SIRT3 knockdown conditions.

KEY FINDINGS

The results showed that, in addition to reducing renal interstitial pathologic injury and collagen fibrils, rhein administration improved renal function. The protective mechanisms were attributed to active SIRT3/FOXO3α signalling pathway and then play the anti-oxidative capacity of rhein, as well as to subsequent antifibrotic effect.

CONCLUSION

Taken together, rhein protected kidney through SIRT3/FOXO3a involvement. The anti-oxidative capacity of rhein contributed to the protective effects including the subsequent antifibrotic responses.

Rhein, a novel Histone Deacetylase (HDAC) inhibitor with antifibrotic potency in human myocardial fibrosis

Although fibrosis depicts a reparative mechanism, maladaptation of the heart due to excessive production of extracellular matrix accelerates cardiac dysfunction. The anthraquinone Rhein was examined for its anti-fibrotic potency to mitigate cardiac fibroblast-to-myofibroblast transition (FMT). Primary human ventricular cardiac fibroblasts were subjected to hypoxia and characterized with proteomics, transcriptomics and cell functional techniques. Knowledge based analyses of the omics data revealed a modulation of fibrosis-associated pathways and cell cycle due to Rhein administration during hypoxia, whereas p53 and p21 were identified as upstream regulators involved in the manifestation of cardiac fibroblast phenotypes. Mechanistically, Rhein acts inhibitory on HDAC classes I/II as enzymatic inhibitor. Rhein-mediated cellular effects were linked to the histone deacetylase (HDAC)-dependent protein stabilization of p53 under normoxic but not hypoxic conditions. Functionally, Rhein inhibited collagen contraction, indicating anti-fibrotic property in cardiac remodeling. This was accompanied by increased abundance of SMAD7, but not SMAD2/3, and consistently SMAD-specific E3 ubiquitin ligase SMURF2. In conclusion, this study identifies Rhein as a novel potent direct HDAC inhibitor that may contribute to the treatment of cardiac fibrosis as anti-fibrotic agent. As readily available drug with approved safety, Rhein constitutes a promising potential therapeutic approach in the supplemental and protective intervention of cardiac fibrosis.

Anthraquinones and autophagy - Three rings to rule them all?

In order to overcome therapy resistance in cancer, scientists search in nature for novel lead structures for the development of improved chemotherapeutics. Anthraquinones belong to a class of tricyclic organic natural compounds with promising anti-cancer effects. Anthraquinone derivatives are rich in structural diversity, and exhibit pleiotropic properties, among which the modulation of autophagy seems promising in the context of overcoming cancer-therapy resistance. Among the most promising derivatives in this regard are emodin, aloe emodin, rhein, physcion, chrysophanol and altersolanol A. On the molecular level, these compounds target autophagy via different upstream pathways including the AKT/mTOR-axis and transcription of autophagy-related proteins. The role of autophagy is pro-survival as well as cell death-promoting, depending on derivatives and their cell type specificity. This review summarizes observed effects of anthraquinone derivatives on autophagy and discusses targeted pathways and crosstalks. A cumulative knowledge about this topic paves the way for further research on modes of action, and aids to find a therapeutic window of anthraquinones in cancer-therapy.

Boldine Improves Kidney Damage in the Goldblatt 2K1C Model Avoiding the Increase in TGF-β

Boldine, a major aporphine alkaloid found in the Chilean boldo tree, is a potent antioxidant. Oxidative stress plays a detrimental role in the pathogenesis of kidney damage in renovascular hypertension (RVH). The activation of the renin-angiotensin system (RAS) is crucial to the development and progression of hypertensive renal damage and TGF-β is closely associated with the activation of RAS. In the present study, we assessed the effect of boldine on the progression of kidney disease using the 2K1C hypertension model and identifying mediators in the RAS, such as TGF-β, that could be modulated by this alkaloid. Toward this hypothesis, rats (n = 5/group) were treated with boldine (50 mg/kg/day, gavage) for six weeks after 2K1C surgery (pressure ≥ 180 mmHg). Kidney function was evaluated by measuring of proteinuria/creatininuria ratio (U prot/U Crea), oxidative stress (OS) by measuring thiobarbituric acid reactive substances (TBARS). The evolution of systolic blood pressure (SBP) was followed weekly. Alpha-smooth muscle actin (α-SMA) and Col III were used as markers of kidney damage; ED-1 and osteopontin (OPN) were used as markers of inflammation. We also explored the effect in RAS mediators, such as ACE-1 and TGF-β. Boldine treatment reduced the UProt/UCrea ratio, plasma TBARS, and slightly reduced SBP in 2K1C hypertensive rats, producing no effect in control animals. In 2K1C rats treated with boldine the levels of α-SMA, Col III, ED-1, and OPN were lower when compared to 2K1C rats. Boldine prevented the increase in ACE-1 and TGF-β in 2K1C rats, suggesting that boldine reduces kidney damage. These results suggest that boldine could potentially be used as a nutraceutic.

Kidney-targeted drug delivery via rhein-loaded polyethyleneglycol-co-polycaprolactone-co-polyethylenimine nanoparticles for diabetic nephropathy therapy

Introduction

Diabetic nephropathy (DN) is the primary root of morbidity and mortality in diabetic patients. Unfortunately, currently, no effective therapeutic strategies are available to ameliorate and reverse the progression of DN. Rhein (RH) is an anthraquinone derivative extracted from herbal medicines with various pharmacological effects on DN. However, its clinical administration is limited by its poor solubility, low bioavailability, reduced distribution into the kidney and adverse effects.

Methods and results

To improve the delivery of RH into kidney and the therapeutic effect on DN, we synthesized and utilized polyethyleneglycol-co-polycaprolactone-co-polyethylenimine triblock amphiphilic polymers to prepare RH-loaded polyethyleneglycol-co-polycaprolactone-co-polyethylenimine nanoparticles (PPP-RH-NPs). PPP-RH-NP size was optimized to 75 ± 25 nm for kidney-targeted drug delivery; the positive zeta potential allowed an effective cellular uptake and the polyethylenimine amine groups facilitate the endosomal escape quickly. The distribution and pharmacodynamics of PPP-RH-NPs were studied in a streptozocin-induced DN model, which explicitly demonstrated kidney-targeted distribution and improved the therapeutic effects of RH on DN by ameliorating several pathological indicators.

Conclusion

Therefore, this study not only stimulates further clinical research on RH but also, more importantly, proposes a promising DN therapy consisting of an effective kidney-targeted drug delivery.

Rhein and polydimethylsiloxane functionalized carbon/carbon composites as prosthetic implants for bone repair applications

A major issue in bone tissue engineering is the selection of biocompatible materials for implants, to reduce unwanted inflammatory reactions and promote cell adhesion. Bone tissue growth on suitable biomedical implants can shorten recovery and hospitalization after surgery. Therefore, a method to improve tissue-implant integration and healing would be of scientific and clinical interest. In this work, we permeated polydimethylsiloxane (PDMS) into carbon/carbon (C/C) composites (PDMS-C/C) and then coated it with 4,5-dihydroxyanthraquinone-2-carboxylic acid (rhein) to create rhein-PDMS-C/C to increase its biocompatibility and reduce the occurrence of inflammatory reactions. We measured in vitro adhesion and proliferation of MC3T3-E1 cells and bacteria to evaluate the biocompatibility and antimicrobial properties of C/C, PDMS-C/C, and rhein-PDMS-C/C. In vivo, x-ray and micro-CT evaluation three, six and nine weeks after surgery revealed that rhein-PDMS-C/C was more effective than PDMS-C/C and C/C composite in terms of antibacterial activity, cell adhesion and tissue growth. Compared with C/C and PDMS-C/C, rhein-PDMS-C/C could be suitable for clinical applications for bone tissue engineering.

Rhein Inhibits Autophagy in Rat Renal Tubular Cells by Regulation of AMPK/mTOR Signaling

Rhubarb and its bioactive component rhein are frequently used for the treatment of chronic kidney diseases (CKD) in eastern Asia countries. However, the potential therapeutic mechanism remains unclear. Autophagy plays an important role in CKD. However, there were some important related issues that remained unresolved in the role of autophagy in CKD and treatment by rhubarb and rhein. We designed a number of experiments to examine whether rhubarb may reduce renal fibrosis and autophagy in rats with adenine (Ade)-induced renal tubular injury, and whether rhein could affect autophagic pathways in rat renal tubular cells. We found that, autophagic activation accompanied with renal fibrosis in rats with Ade-induced renal tubular injury, and both autophagy and renal fibrosis were attenuated by rhubarb. In addition, we observed that rhein could inhibit autophagy through regulating the key molecules in the AMPK-dependent mTOR signaling pathways, as well as the Erk and p38 MAPKs signaling pathways. These findings may partly explain the therapeutic mechanisms of rhubarb and rhein in treating CKD patients in clinic, and further suggest that targeting autophagy and related signaling pathways may provide new strategies for the treatment of renal fibrosis in CKD.

Organic anion transporters 1 (OAT1) and OAT3 meditated the protective effect of rhein on methotrexate-induced nephrotoxicity

Rhein protects methotrexate induced kidney damage mediated by OAT1 and OAT3.

Pharmacokinetics and pharmacodynamics study of rhein treating renal fibrosis based on metabonomics approach

BACKGROUND

The selection of effect indicators in the pharmacokinetic/ pharmacodynamic study of complex diseases to describe the relationship between plasma concentration and effect indicators is difficult.

PURPOSE

Three effect indicators of renal fibrosis were successfully determined. The relationship between pharmacokinetics and pharmacodynamics of rhein in rhubarb was elucidated.

STUDY DESIGN

The study was a metabolomics analysis of rat plasma and pharmacokinetics/ pharmacodynamics of rhein.

METHODS

A sensitive and simple ultra performance liquid chromatography-tandem triple quadrupole mass spectrometry (UPLC-MS/MS) method was applied to determine the rhein plasma concentration in the rat model of renal fibrosis and rat sham-operated group after the administration of rhubarb decoction. Then, the ultra performance liquid chromatography-Micromass quadrupole-time of flight mass spectrometry (UPLC-QTOF/MS) metabolomics method was used to screen biomarkers of renal fibrosis in rat plasma. Furthermore, the relationship between the plasma concentration of rhein and the concentration of three biomarkers directly related to renal fibrosis were analyzed.

RESULTS

The three screened biomarkers could represent the effect of rhein treatment on renal fibrosis. Increasing the plasma concentration of rhein tended to restore the concentration of the three biomarkers in the model group compared with that in the sham-operated group. Evident differences in the area under the plasma concentration-time curve (AUC) of rhein were also observed under different pathological states. The results provide valuable information for the clinical application of rhubarb.

CONCLUSION

Rhein intervention could recover the physiological balance in living organisms from the pharmacokinetic/pharmacodynamic levels. New information on the pharmacokinetic/pharmacodynamic study of complex diseases is provided.

Rhein reversal of DNA hypermethylation-associated Klotho suppression ameliorates renal fibrosis in mice

Renal fibrosis is the hallmark of chronic kidney diseases (CKD) and its development and progression are significantly affected by epigenetic modifications. Rhein, a plant-derived anthraquinone, displays strong anti-fibrosis properties, but its protective mode of action remains incompletely understood. Here we explore the mechanism of Rhein anti-renal fibrosis by investigating its regulation of Klotho, a known renal anti-fibrotic protein whose suppression after renal injury reportedly involves aberrant DNA methylation. We report that Rhein is an impressive up-regulator of Klotho and it markedly reversed Klotho down-regulation in unilateral ureteral occlusion-induced fibrotic kidney. Further examinations revealed that Klotho loss in fibrotic kidney is associated with Klotho promoter hypermethylation due to aberrant methyltransferase 1 and 3a expressions. However, Rhein significantly corrected all these epigenetic alterations and subsequently alleviated pro-fibrotic protein expression and renal fibrosis, whereas Klotho knockdown via RNA interferences largely abrogated the anti-renal fibrotic effects of Rhein, suggesting that Rhein epigenetic reversal of Klotho loss represents a critical mode of action that confers Rhein’s anti- renal fibrotic functions. Altogether our studies uncover a novel hypomethylating character of Rhein in preventing Klotho loss and renal fibrosis, and demonstrate the efficacy of Klotho-targeted epigenetic intervention in potential treatment of renal fibrosis-associated kidney diseases.

A Comprehensive and System Review for the Pharmacological Mechanism of Action of Rhein, an Active Anthraquinone Ingredient

Rhein is a major medicinal ingredient isolated from several traditional Chinese medicines, including Rheum palmatum L., Aloe barbadensis Miller, Cassia angustifolia Vahl., and Polygonum multiflorum Thunb. Rhein has various pharmacological activities, such as anti-inflammatory, antitumor, antioxidant, antifibrosis, hepatoprotective, and nephroprotective activities. Although more than 100 articles in PubMed are involved in the pharmacological mechanism of action of rhein, only a few focus on the relationship of crosstalk among multiple pharmacological mechanisms. The mechanism of rhein involves multiple pathways which contain close interactions. From the overall perspective, the pathways which are related to the targets of rhein, are initiated by the membrane receptor. Then, MAPK and PI3K-AKT parallel signaling pathways are activated, and several downstream pathways are affected, thereby eventually regulating cell cycle and apoptosis. The therapeutic effect of rhein, as a multitarget molecule, is the synergistic and comprehensive result of the involvement of multiple pathways rather than the blocking or activation of a single signaling pathway. We review the pharmacological mechanisms of action of rhein by consulting literature published in the last 100 years in PubMed. We then summarize these pharmacological mechanisms from a comprehensive, interactive, and crosstalk perspective. In general, the molecular mechanism of action of drug must be understood from a systematic and holistic perspective, which can provide a theoretical basis for precise treatment and rational drug use.

Toll-like receptor 4 is involved in a protective effect of rhein on immunoglobulin A nephropathy

OBJECTIVES

The objective was to investigate the protective effects of rhein on renal histology change and the effects of rhein on renal tissue toll-like receptor (TLR) 4, TLR9, transforming growth factor-β1 (TGF-β1) expression in immunoglobulin A nephropathy (IgAN) rats.

MATERIALS AND METHODS

Bovine serum albumin-lipopolysaccharide-carbon tetrachloride 4 method was used to establish IgAN model. Thirty-two male sprague dawley rats were randomly divided into the control group, IgAN model group, rhein-prevented group, and rhein-treated group. 24-h urinary protein (UP), creatinine, urea, alanine aminotransferase (ALT), total protein (TP) contents in the serum of rats were detected with automatic biochemical analyzer and renal pathological changes were observed by the hematoxylin and eosin and periodic acid-Schiff staining. The glomerular deposition of IgA was measured by immunofluorescence staining. Real-time polymerase chain reaction and immunohistochemistry were used to detect renal tissue contents of TLR4, TLR9, TGF-β1 messenger ribonucleic acid and protein expression.

RESULTS

The biochemical parameters results of IgAN model rats showed that the 24-h UP excretion and ALT concentration were much higher, and TP concentration was much lower than those of the control group (P < 0.05). Granule-like or mass-like IgA depositions in the mesangial area, glomerular hypercellularity, hyperplasia of mesangial matrix, and tubulointerstitial fibrosis were found in IgAN group. Rhein-prevented and rhein-treated both improved the biochemical parameters and relieved renal pathological injury. The expressions of renal tissue TLR4, TGF-β1, but not TLR9 were significantly elevated in IgAN model rats (P < 0.05). Rhein-prevented and rhein-treated both inhibited TLR4 and TGF-β1 expressions.

CONCLUSION

Rhein significantly improved the serum and urine biochemical parameters, and attenuated the glomerular pathological changes and tubulointerstitial fibrosis in IgAN rats. The mechanism may involve inhibition of renal TLR4 and TGF-β1 secretion.

Effects and Mechanism of Combination of Rhein and Danshensu in the Treatment of Chronic Kidney Disease

Traditional Chinese medicine (TCM) plays a systemic role in disease treatment, targeting multiple etiological factors simultaneously. Based on clinical experience, rhubarb and Salvia miltiorrhiza are commonly prescribed together for the treatment of chronic kidney disease (CKD) and have been proven to be very effective. However, the rationale of the combination remains unclear. The major active ingredients of these two herbs are rhein (RH) and danshensu (DSS), respectively. The aim of this paper is to investigate the renoprotective effects of RH and DSS in vitro and in vivo, and the underlying mechanism. A total of 5/6 nephrectomy rats and HK-2 cells were subjected to chronic renal injury. The combination of RH and DSS conferred a protective effect, as shown by a significant improvement in the renal function, blood supply, and fibrotic degree. Proinflammatory cytokines and adhesion molecules were suppressed by RH and DSS through NK-κB signaling. The combination also inhibited apoptosis by up-regulating Bcl-2 and down-regulating Bax. Inhibiting the TGF-β/Smad3 pathway was at least in part involved in the antifibrotic mechanism of the combination treatment of RH and DSS. This study demonstrates for the first time the renoprotective effect and the mechanism of RH and DSS combination on chronic renal injury. It could provide experimental evidence to support the rationality of the combinatorial use of TCM in clinical practices.

Rhein prevents endotoxin-induced acute kidney injury by inhibiting NF-κB activities

This study aimed to explore the effect and mechanisms of rhein on sepsis-induced acute kidney injury by injecting lipopolysaccharide (LPS) and cecal ligation and puncture (CLP) in vivo, and on LPS-induced HK-2 cells in vitro. For histopathological analysis, rhein effectively attenuated the severity of renal injury. Rhein could significantly decrease concentration of BUN and SCr and level of TNF-α and IL-1β in two different mouse models of experimental sepsis. Moreover, rhein could markedly attenuate circulating leukocyte infiltration and enhance phagocytic activity of macrophages partly impaired at 12 h after CLP. Rhein could enhance cell viability and suppresse the release of MCP-1 and IL-8 in LPS-stimulated HK-2 cells Furthermore, rhein down regulated the expression of phosphorylated NF-κB p65, IκBα and IKKβ stimulated by LPS both in vivo and in vitro. All these results suggest that rhein has protective effects on endotoxin-induced kidney injury. The underlying mechanism of rhein on anti-endotoxin kidney injury may be closely related with its anti-inflammatory and immunomodulatory properties by decreasing NF-κB activation through restraining the expression and phosphorylation of the relevant proteins in NF-κB signal pathway, hindering transcription of NF-κB p65.These evidence suggest that rhein has a potential application to treat endotoxemia-associated acute kidney injury.

Rhein: A Review of Pharmacological Activities

Rhein (4, 5-dihydroxyanthraquinone-2-carboxylic acid) is a lipophilic anthraquinone extensively found in medicinal herbs, such as Rheum palmatum L., Cassia tora L., Polygonum multiflorum Thunb., and Aloe barbadensis Miller, which have been used medicinally in China for more than 1,000 years. Its biological activities related to human health are being explored actively. Emerging evidence suggests that rhein has many pharmacological effects, including hepatoprotective, nephroprotective, anti-inflammatory, antioxidant, anticancer, and antimicrobial activities. The present review provides a comprehensive summary and analysis of the pharmacological properties of rhein, supporting the potential uses of rhein as a medicinal agent.

Protective effect of Huang Gan formula in 5/6 nephrectomized rats by depressing the Wnt/β-catenin signaling pathway

Huang Gan formula (HGF) is a new traditional Chinese herbal medicine created according to the basic theory of traditional Chinese medicine. The aim of this study is to evaluate the effects of HGF on chronic kidney disease and determine the mechanisms of action. The extract of HGF was prepared, and qualitative and quantitative determination of phytochemical was performed with quadrupole time-of-flight mass spectrometer and high-performance liquid chromatography. Sprague-Dawley rats (n=72) were submitted to 5/6 nephrectomy (Nx), and then respectively treated with uremic clearance granule, losartan, HGF low dose, HGF middle dose, and HGF high dose once per day for 12 weeks. The sham group of operated rats (n=22) was treated with normal saline or HGF middle dose as a background control group. Blood and urine biochemical parameters, renal tissue morphology, and mRNA and proteins of Wnt/β-catenin signaling pathways were investigated. The results showed that the quality of the extraction process could be controlled, and a total of eight major compounds were identified and quantified. HGF could decrease the level of serum creatinine, blood urea nitrogen, and urine protein and increase the renal index and creatinine clearance rate in a dose-dependent manner. HGF also remarkably reduced the glomerulosclerosis and tubulointerstitial fibrosis by blocking the Wnt/β-catenin signaling pathway through inhibiting the Wnt1, β-catenin, transcription factor 4, and fibronectin 1 expressions, simultaneously measured through mRNA and protein levels in the remnant kidney. These results suggest that extraction of HGF could improve remnant renal function and possibly ameliorate glomerulosclerosis and tubulointerstitial fibrosis by depressing the Wnt/β-catenin signaling pathway.

KS370G, a caffeamide derivative, attenuates unilateral ureteral obstruction-induced renal fibrosis by the reduction of inflammation and oxidative stress in mice

Unilateral ureteral obstruction (UUO) is an established animal model used to study renal nephropathy. Caffeic acid phenethyl ester, a natural phenolic compound, possesses antifibrotic, anti-inflammation and anti-oxidative stress effects; however, rapid decomposition by esterases substantially decreases its bioavailability. The goal of this study was to investigate the beneficial effects of KS370G, a synthetic caffeamide derivative, on UUO-induced renal injury. Following the UUO, KS370G (10mg/kg) was administered by oral gavage once a day. Renal injury was analyzed at 14 days post-operation. Our results show that KS370G significantly attenuated collagen deposition in the obstructed kidney and inhibited UUO-induced renal fibrosis markers expression, including fibronectin, type I collagen, vimentin, and α-smooth muscle actin (α-SMA). KS370G significantly lowered the expression of renal inflammatory chemokines/adhesion molecules and monocyte cells marker (MCP-1, VCAM-1, ICAM-1 and CD11b). KS370G also reduced renal malondialdehyde levels and reversed the expression of renal antioxidant enzymes (SOD and catalase) after UUO. Furthermore, KS370G significantly inhibited UUO-induced elevated plasma AngII and TGF-β1 levels, TGF-β1 protein expression and Smad3 phosphorylation. These findings demonstrate that KS370G reduces renal obstructive nephropathy by possibly inhibiting AngII, TGF-β and Smad3 signaling pathways.

Dahuang Fuzi Decoction ameliorates tubular epithelial apoptosis and renal damage via inhibiting TGF-β1-JNK signaling pathway activation in vivo

ETHNOPHARMACOLOGICAL RELEVANCE

Dahuang Fuzi Decoction (DFD) is a traditional well-prescribed formula for the treatment of chronic kidney disease (CKD) in China. This study was carried out to examine the effects of DFD in adenine-induced tubular epithelial apoptosis and renal damage, in comparison with allopurinol (AP), then to clarify the therapeutic mechanisms in vivo.

MATERIALS AND METHODS

A rat model of renal damage was created by adenine. Rats in Normal and Vehicle groups received distilled water, while rats in DFD and AP groups received DFD and AP, respectively. Proteinuria; urinary N-acetyl-β-D-glucosaminidase (NAG) levels; the blood biochemical parameters; renal histopathology damage; transferase-mediated dUTP nick-end labeling (TUNEL)-staining; the key molecular protein expressions in mitochondrial and transforming growth factor (TGF)-β1-c-JunNH2-terminal kinase (JNK) pathways were examined, respectively.

RESULTS

Adenine administration induced severe renal damages, as indicated by the mass proteinuria, the heavy urinary NAG, and the marked histopathological injury in tubules and interstitium. This was associated with the activation of TGF-β1-JNK signaling pathway and tubular epithelial apoptosis. DFD treatment, however, significantly prevented proteinuria and urinary NAG elevation, and attenuated tubular epithelial apoptosis. It suppressed the protein expressions of Bax and cleaved caspase-3, whereas it enhanced the protein expression of Bcl-2. Furthermore, it also suppressed the protein levels of TGF-β1 as well as phosphorylated-JNK (p-JNK).

CONCLUSION

DFD alleviated adenine-induced tubular epithelial apoptosis and renal damage in vivo, presumably through the suppression of TGF-β1-JNK pathway activation.

The potential signal pathway between PAX2 and CD2AP in the renal interstitial fibrosis disease

Paired box gene 2 (PAX2) can regulate tissue development and cellular differentiation, and it is associated with renal diseases. CD2-associated protein (CD2AP) is an adaptor protein involving in a variety of physiological and disease processes. Renal interstitial fibrosis (RIF) is a hallmark of common progressive chronic diseases which lead to renal failure. This study was performed to investigate whether there was a potential signal pathway between PAX2 and CD2AP in RIF rats induced by unilateral ureteral obstruction (UUO). Eighty Wistar male rats were divided into two groups randomly: sham operation group (SHO) and model group subjected to UUO (GU), n = 40. The model was established by left ureteral ligation. Renal tissues were collected at 14 d and 28 d after surgery. RIF index, cell apoptosis index, protein expression of PAX2, CD2AP, transforming growth factor-βl (TGF-β1), collagen-IV (Col-IV), fibronectin (FN) in renal interstitium and renal tissue, and mRNA expression of PAX2, CD2AP, and TGF-β1 in renal tissue were detected. Compared with that in the SHO group, the PAX2 and CD2AP expressions (mRNA and protein) were significantly increased (p < 0.01). Protein expressions of TGF-β1, Col-IV, and FN, and RIF index or cell apoptosis index in the GU group were markedly elevated than those in the SHO group (all p < 0.01). PAX2 or CD2AP was positively correlated with TGF-β1, Col-IV, and FN, and RIF index or cell apoptosis index (all p < 0.05). Furthermore, PAX2 was positively correlated with CD2AP (p < 0.05). In conclusion, the expression of PAX2 or CD2AP was increased in RIF rats, and PAX2 was positively correlated with CD2AP. There might be a potential signaling pathway between PAX2 and CD2AP in RIF disease. Further research is needed to determine the association in RIF disease.

Chronic allograft nephropathy in rats is improved by the intervention of rhein

AIM

In this study, we investigated the therapeutic efficacy and potential mechanisms of rhein to mitigate chronic allograft nephropathy (CAN) in rats.

MATERIALS AND METHODS

Fisher rat donors and Lewis rat recipients were used to establish the CAN model. Thirty rats with transplanted kidneys were randomly divided into two groups: 16 untreated and 14 rhein = treated rats. Five Lewis rat controls underwent removal of their right kidneys. The Intervention group was administered rhein oral solution (100 mg kg(-1) d(-1)) by gavage after transplantation. The untreated and control groups were given 0.5% sodium carboxymethyl cellulose. Blood and urine samples were collected at 4, 8, and 16 weeks to examine renal function and total urine protein. Half of the rats in each group were sacrifice at 8 or 16 weeks to examine renal pathology. Immunohistochemical examination and real-time polymerase chain reaction of renal tissues were performed to detect expressions of transforming growth-β1(TGF-β1), hepatic growth factor (HGF), bone morphogenetic protein 7 (BMP7), frobronectin, and collgen IV.

RESULTS

Rhein improved renal function and significantly reduced renal fibrosis and interstitial inflammation. The levels of BMP7 and HGF were significantly elevated in the renal tissues of the rhein intervention group. In the meantime, fibronectin and collagen IV were decreased in the extracellular matrix. The expression of TGF-β1 was similar between these two groups.

CONCLUSION

Rhein improved renal function and reduced renal fibrosis and interstitial inflammation by inducing production of HGF and BMP7.

Effects of an astragalus polysaccharide and rhein combination on apoptosis in rats with chronic renal failure

Objective. To investigate the effects and to analyze the mechanism of the combination of Astragalus polysaccharide (APS) and Rhein on apoptosis in rats with chronic renal failure (CRF). Methods. Thirty-seven male Wistar rats were randomly divided into a control group, a model group, a low-dose APS and Rhein combination group, and a high-dose APS and Rhein combination group. CRF was induced by orogastric gavage with adenine. Rats were observed for renal function, electrolyte, and pathological changes for 7 weeks after administration. Renal tubular cell apoptosis was assessed by TUNEL and protein expressions of IRE1 and CHOP were detected by Western-blotting. Results. The combination of APS and Rhein decreased the kidney weight and index, improved renal pathological injury, maintained the stability of serum electrolytes, and reduced SCr and BUN levels in rat models. Moreover, APS and Rhein combination could effectively inhibit the apoptosis and reduce the protein expressions of IRE1and CHOP of renal tubular cells. Conclusions. The combination of APS and Rhein could improve renal function and reduce renal cell apoptosis to protect against further progression of CRF, whose mechanism may be related to alleviate endoplasmic reticulum stress (ERS) in the renal cells.

A network pharmacology approach to understanding the mechanisms of action of traditional medicine: Bushenhuoxue formula for treatment of chronic kidney disease

Traditional Chinese medicine (TCM) has unique therapeutic effects for complex chronic diseases. However, for the lack of an effective systematic approach, the research progress on the effective substances and pharmacological mechanism of action has been very slow. In this paper, by incorporating network biology, bioinformatics and chemoinformatics methods, an integrated approach was proposed to systematically investigate and explain the pharmacological mechanism of action and effective substances of TCM. This approach includes the following main steps: First, based on the known drug targets, network biology was used to screen out putative drug targets; Second, the molecular docking method was used to calculate whether the molecules from TCM and drug targets related to chronic kidney diseases (CKD) interact or not; Third, according to the result of molecular docking, natural product-target network, main component-target network and compound-target network were constructed; Finally, through analysis of network characteristics and literature mining, potential effective multi-components and their synergistic mechanism were putatively identified and uncovered. Bu-shen-Huo-xue formula (BSHX) which was frequently used for treating CKD, was used as the case to demonstrate reliability of our proposed approach. The results show that BSHX has the therapeutic effect by using multi-channel network regulation, such as regulating the coagulation and fibrinolytic balance, and the expression of inflammatory factors, inhibiting abnormal ECM accumulation. Tanshinone IIA, rhein, curcumin, calycosin and quercetin may be potential effective ingredients of BSHX. This research shows that the integration approach can be an effective means for discovering active substances and revealing their pharmacological mechanisms of TCM.

Protection of rhein on IgA nephropathy mediated by inhibition of fibronectin expression in rats

Objective:

To investigate the protective effects of rhein on IgA nephropathy (IgAN) in the rat model.

Materials and Methods:

Twenty-eight female sprague dawley rats were divided randomly into four groups, namely control, IgAN, rhein-prevented and rhein-treated. The pathologic changes on renal tissue were observed by the H and E, staining and the amount of urinary red blood cells and 24-h urinary protein excretion were measured. The glomerular deposition of immune globulin A (IgA) was measured by immunofluorescence staining. Fibronectin (FN) and α-smooth muscle actin (α-SMA) expression on renal tissue were measured via immunohistochemistry.

Results:

The model of IgAN was established according to Bovine serum albumin-Lipopolysaccharide-Carbon tetrachloride protocol, which was evidenced by histological structural lesions of glomeruli, IgA deposition and urinary measurement. Histological examination of kidney sections from both rhein-prevented group and rhein-treated group showed that glomerular hypertrophy, mesangial expansion, excessive extracellular matrix, and renal capsule dilation were markedly ameliorated compared with IgAN group. Moreover, rhein treatment significantly reduced IgA deposition in glomerulus, the volume of urinary red blood cells and 24-h urinary protein excretion. More importantly, increased FN expression in IgAN was back to normal level in rhein-prevented and rhein-treated group, which was along with the reduction of α-SMA expression in renal tissues.

Conclusions:

These findings indicate that rhein prevents the development of glomerulosclerosis and halts the progression of IgAN via inhibition of FN and α-SMA expression.

Rhein, a natural anthraquinone derivative, attenuates the activation of pancreatic stellate cells and ameliorates pancreatic fibrosis in mice with experimental chronic pancreatitis

Pancreatic fibrosis, a prominent histopathological feature of chronic pancreatitis (CP) and pancreatic ductal adenocarcinoma, is essentially a dynamic process that leads to irreversible scarring of parenchymal tissues of the pancreas. Though the exact mechanisms of its initiation and development are poorly understood, recent studies suggested that the activation of pancreatic stellate cells (PSCs) plays a critical role in eliciting such active course of fibrogenesis. Anthraquinone compounds possess anti-inflammatory bioactivities whereas its natural derivative rhein has been shown to effectively reduce tissue edema and free-radical production in rat models of inflammatory conditions. Apart from its anti-inflammatory properties, rhein actually exerts strong anti-fibrotic effects in our current in-vivo and in-vitro experiments. In the mouse model of cerulein-induced CP, prolonged administration of rhein at 50 mg/kg/day significantly decreased immunoreactivities of the principal fibrotic activators alpha-smooth muscle actin (α-SMA) and transforming growth factor-beta (TGF-β) on pancreatic sections implicating the activation of PSCs, which is the central tread to fibrogenesis, was attenuated. Consequently, the overwhelmed deposition of extracellular matrix proteins fibronectin 1 (FN1) and type I collagen (COL I-α1) in exocrine parenchyma was found accordingly reduced. In addition, the expression levels of sonic hedgehog (SHH), which plays important roles in molecular modulation of various fibrotic processes, and its immediate effector GLI1 in pancreatic tissues were positively correlated to the degree of cerulein-induced fibrosis. Such up-regulation of SHH signaling was restrained in rhein-treated CP mice. In cultured PSCs, we demonstrated that the expression levels of TGF-β-stimulated fibrogenic markers including α-SMA, FN1 and COL I-α1 as well as SHH were all notably suppressed by the application of rhein at 10 μM. The present study firstly reported that rhein attenuates PSC activation and suppresses SHH/GLI1 signaling in pancreatic fibrosis. With strong anti-fibrotic effects provided, rhein can be a potential remedy for fibrotic and/or PSC-related pathologies in the pancreas.

Prohibitin attenuates oxidative stress and extracellular matrix accumulation in renal interstitial fibrosis disease

Prohibitin is an evolutionary conserved and pleiotropic protein that has been implicated in various cellular functions, including proliferation, tumour suppression, apoptosis, transcription, and mitochondrial protein folding. Both prohibitin over- and under-expression have been implicated in various diseases and cell types. We recently demonstrated that prohibitin down-regulation results in increased renal interstitial fibrosis (RIF). Here we investigated the role of oxidative stress and prohibitin expression in RIF in unilateral ureteral obstructed rats. Lentivirus-based delivery vectors were used to knockdown or over-express prohibitin. Our results show that increased prohibitin expression was negatively correlated with the RIF index, reactive oxygen species, malon dialdehyde, transforming growth factor β1, collagen IV, fibronectin, and cell apoptosis index. In conclusion, we postulate that prohibitin acts as a positive regulator of mechanisms that counteract oxidative stress and extracellular matrix accumulation and therefore has an antioxidative effect.

Rhein lysinate increases the median survival time of SAMP10 mice: protective role in the kidney

AIM

To investigate the protective effects of rhein lysinate (RHL), a major bioactive constituent of the rhizome of rhubarb (Rheum palmatum Linn or Rheum tanguticum Maxim), against kidney impairment in senescence-prone inbred strain 10 (SAMP10) mice.

METHODS

SAMP10 mice were orally administered RHL (25 or 50 mg/kg) daily until 50% of the mice died. Senescence-resistant inbred strain 1 (SAMR1) mice administered no drug were taken as control. The kidneys were harvested after animal death, and examined morphologically and with immunochemical assays. The levels of MAD, SOD and GSH-px in the kidneys were measured with a photometric method. The expression of inflammatory factors and related proteins in the kidneys was analyzed using Western blotting.

RESULTS

Treatment of SAMP10 mice with RHL had no effect on the body weight or phenotype. However, RHL significantly prolonged the median survival time of SAMP10 mice by approximately 25%, as compared to untreated SAMP10 mice. Compared SAMR1 mice, SAMP10 mice had a significantly lower level of SOD in the kidneys, but had no significant difference in the MDA or GSH-px levels. Treatment of SAMP10 mice with RHL significantly reduced the MAD level, and increased the SOD and GSH-px levels in the kidneys. Glomerulonephritis was observed in SAMP10 mice but not in SAMR1 mice. RHL decreased the incidence of glomerulonephritis, and significantly decreased the levels of TNF-α, IL-6, NF-κB, collagen types I and III in the kidneys.

CONCLUSION

Accelerated senescence is associated with glomerulonephritis in SAMP10 mice, and RHL prolongs their median survival time by reducing the severity of glomerulonephritis.

Rhein inhibits integrin-linked kinase expression and regulates matrix metalloproteinase-9/tissue inhibitor of metalloproteinase-1 ratio in high glucose-induced epithelial-mesenchymal transition of renal tubular cell

Studies have found overexpressed integrin-linked kinase (ILK) and disturbed matrix metalloproteinase-9/tissue inhibitor of metalloproteinase-1 (MMP-9/TIMP-1) ratio in diabetic nephropathy epithelial-mesenchymal transition (EMT). However, the underlying mechanisms of EMT and the inhibiting effect of rhein need further understanding. The aim of this study was to investigate the possible regulating effects of ILK towards MMP-9/TIMP-1 ratio in EMT and the inhibiting effect of rhein. The characteristic epithelial marker and mesenchymal marker of EMT were examined by cytoimmunostaining, real-time reverse transcription polymerase chain reaction (real-time RT-PCR) and Western blot. To observe the EMT inhibiting effects of rhein, specific ILK-small interfering RNA (ILK-siRNA) was used as a positive control. The results showed that in high glucose conditions, overexpression of ILK and an abnormal changing of MMP-9/TIMP-1 ratio occurred; ILK inhibition by siRNA could adjust MMP-9/TIMP-1 ratio to near normal. Meanwhile, rhein inhibited the overexpressing ILK and inhibits high glucose-induced EMT; the effect was similar to that of ILK-siRNA. The decreased expression of ILK regulated by rhein contributed to the adjustment of the MMP-9/TIMP-1 ratio. Our data indicates that rhein inhibits high glucose-induced-EMT partially through the inhibition of ILK expression and regulates the MMP-9/TIMP-1 ratio in HK-2 cells. This mechanism may be associated with rhein's effect of ILK suppression.