Chrysophanol ameliorates renal interstitial fibrosis by inhibiting the TGF-β/Smad signaling pathway

Sodium arsenite induces hepatic stellate cells activation by m6A modification of TGF-β1 during liver fibrosis

The compound known as Sodium arsenite (NaAsO2), which is a prevalent type of inorganic arsenic found in the environment, has been strongly associated with liver fibrosis (LF), a key characteristic of nonalcoholic fatty liver disease (NAFLD), which has been demonstrated in our previous study. Our previous research has shown that exposure to NaAsO2 triggers the activation of hepatic stellate cells (HSCs), a crucial event in the development of LF. However, the molecular mechanism is still unknown. N6-methyladenosine (m6A) modification is the most crucial post-transcriptional modification in liver disease. Nevertheless, the precise function of m6A alteration in triggering HSCs and initiating LF caused by NaAsO2 remains unknown. Here, we found that NaAsO2 induced LF and HSCs activation through TGF-β/Smad signaling, which could be reversed by TGF-β1 knockdown. Furthermore, NaAsO2 treatment enhanced the m6A modification level both in vivo and in vitro. Significantly, NaAsO2 promoted the specific interaction of METTL14 and IGF2BP2 with TGF-β1 and enhanced the TGF-β1 mRNA stability. Notably, NaAsO2-induced TGF-β/Smad pathway and HSC-t6 cells activation might be avoided by limiting METTL14/IGF2BP2-mediated m6A modification. Our findings showed that the NaAsO2-induced activation of HSCs and LF is made possible by the METTL14/IGF2BP2-mediated m6A methylation of TGF-β1, which may open up new therapeutic options for LF brought on by environmental hazards.

N-acetylcysteine regulates oxalate induced injury of renal tubular epithelial cells through CDKN2B/TGF-β/SMAD axis

This study was aimed to investigate the preventive effects of N-acetyl-L-cysteine (NAC) against renal tubular cell injury induced by oxalate and stone formation and further explore the related mechanism. Transcriptome sequencing combined with bioinformatics analysis were performed to identify differentially expressed gene (DEG) and related pathways. HK-2 cells were pretreated with or without antioxidant NAC/with or silencing DEG before exposed to sodium oxalate. Then, the cell viability, oxidative biomarkers of superoxidase dismutase (SOD) and malondialdehyde (MDA), apoptosis and cell cycle were measured through CCK8, ELISA and flow cytometry assay, respectively. Male SD rats were separated into control group, hyperoxaluria (HOx) group, NAC intervention group, and TGF-β/SMAD pathway inhibitor group. After treatment, the structure changes and oxidative stress and CaOx crystals deposition were evaluated in renal tissues by H&E staining, immunohistochemical and Pizzolato method. The expression of TGF-β/SMAD pathway related proteins (TGF-β1, SMAD3 and SMAD7) were determined by Western blot in vivo and in vitro. CDKN2B is a DEG screened by transcriptome sequencing combined with bioinformatics analysis, and verified by qRT-PCR. Sodium oxalate induced declined HK-2 cell viability, in parallel with inhibited cellular oxidative stress and apoptosis. The changes induced by oxalate in HK-2 cells were significantly reversed by NAC treatment or the silencing of CDKN2B. The cell structure damage and CaOx crystals deposition were observed in kidney tissues of HOx group. Meanwhile, the expression levels of SOD and 8-OHdG were detected in kidney tissues of HOx group. The changes induced by oxalate in kidney tissues were significantly reversed by NAC treatment. Besides, expression of SMAD7 was significantly down-regulated, while TGF-β1 and SMAD3 were accumulated induced by oxalate in vitro and in vivo. The expression levels of TGF-β/SMAD pathway related proteins induced by oxalate were reversed by NAC. In conclusion, we found that NAC could play an anti-calculus role by mediating CDKN2B/TGF-β/SMAD axis.

Rehmannia glutinosa Libosch and Cornus officinalis Sieb herb couple ameliorates renal interstitial fibrosis in CKD rats by inhibiting the TGF-β1/MAPK signaling pathway

ETHNOPHARMACOLOGICAL RELEVANCE

Herb couple Rehmannia glutinosa Libosch and Cornus officinalis Sieb (RC), originated from "Liuwei Dihuang Pill" which recorded in Key to Therapeutics of Children's Diseases. Traditionally, they have been used widely for their ability to nourish yin and energize the kidneys. Our previous study indicated that the RC could protect against adenine induced Chronic kidney disease (CKD) rats. Nevertheless, there is still no clear explanation of the mechanisms by which RC affects renal interstitial fibrosis in CKD rats.

AIM OF THE STUDY

Current Work aims to explore the amelioration and potential mechanism of RC on renal interstitial fibrosis in CKD rats.

MATERIALS AND METHODS

CKD rats were induced by adenine. Two weeks after administration, blood, urine, and kidney tissue were collected for biochemical analysis. Observing the physiological state of rats through the changes of rat body weight and renal index. The pro-inflammatory cytokines were measured by enzyme linked immunosorbent assay (ELISA), while renal tissue damage and fibrosis were assessed with Hematoxylin-eosin staining (H&E) and Masson's trichrome staining. In order to determine the levels of indicators and proteins associated with fibrosis signaling pathways, real time PCR (Rt-PCR), Western blot (WB), and immunofluorescence were employed.

RESULTS

The renal interstitial fibrosis led to impaired cellular functions with increased the levels of Blood Urea Nitrogen (BUN), Urine protein (UP), Interleukin-1β (IL-1β), Interleukin-6 (IL-6), and Tumor Necrosis Factor alpha (TNF-α). and simultaneous up-regulated collagenⅠ(COL-1), fibronection (FN), α-smooth muscle actin (a-SMA), transforming growth factor-β1 (TGF-β1), c-Jun N-terminal kinase (JNK), p38 and extracellular regulated protein kinases (ERK), down-regulated the expression of the E-cadherin proteins. RC notably improved renal dysfunction in CKD rats as indicated by decreases in BUN, UP, and renal index. In addition, consistent with the morphological changes of renal tissue, renal interstitial fibrosis in CKD rats after RC intervention was significantly improved, mainly manifested by a decrease in the positive expression of COL-1, FN, and a-SMA, and increased levels of E-cadherin protein. Meanwhile, RC reduced the classical pro-inflammatory cytokines IL-1β, IL-6, and TNF-α in adenine-induced CKD rats. Additionally, RC administration also down-regulated TGF-β1, JNK, p38 and ERK.

CONCLUSION

In conclusion, RC may reduce inflammation in adenine induced CKD rats, improve extracellular matrix (ECM) components deposition, and diminish epithelial-mesenchymal transition (EMT) marker protein levels. Furthermore, RC intervention significantly reduces the release of inflammatory cytokines and inhibits the TGF-β1/MAPK signaling pathway. Based on the results, RC might be useful in the treatment of adenine induced renal fibrosis.

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.

Antioxidant therapy against TGF-β/SMAD pathway involved in organ fibrosis

Fibrosis refers to excessive build-up of scar tissue and extracellular matrix components in different organs. In recent years, it has been revealed that different cytokines and chemokines, especially Transforming growth factor beta (TGF-β) is involved in the pathogenesis of fibrosis. It has been shown that TGF-β is upregulated in fibrotic tissues, and contributes to fibrosis by mediating pathways that are related to matrix preservation and fibroblasts differentiation. There is no doubt that antioxidants protect against different inflammatory conditions by reversing the effects of nitrogen, oxygen and sulfur-based reactive elements. Oxidative stress has a direct impact on chronic inflammation, and as results, prolonged inflammation ultimately results in fibrosis. Different types of antioxidants, in the forms of vitamins, natural compounds or synthetic ones, have been proven to be beneficial in the protection against fibrotic conditions both in vitro and in vivo. In this study, we reviewed the role of different compounds with antioxidant activity in induction or inhibition of TGF-β/SMAD signalling pathway, with regard to different fibrotic conditions such as gastro-intestinal fibrosis, cardiac fibrosis, pulmonary fibrosis, skin fibrosis, renal fibrosis and also some rare cases of fibrosis, both in animal models and cell lines.

Silymarin ameliorates peritoneal fibrosis by inhibiting the TGF-β/Smad signaling pathway

Peritoneal dialysis (PD) is the mainstay of treatment for renal failure replacement therapy. Although PD has greatly improved the quality of life of end-stage renal disease (ESRD) patients, long-term PD can lead to ultrafiltration failure, which in turn causes peritoneal fibrosis (PF). Silymarin (SM) is a polyphenolic flavonoid isolated from the milk thistle (Silybum marianum) species that has a variety of pharmacological actions, including antioxidant, anti-inflammatory, antiviral, and anti-fibrotic pharmacological activities. However, the effect of SM on PF and its potential mechanisms have not been clarified. The aim of this study was to investigate the preventive effect of SM on PF in vitro and in vivo as well as elucidate the underlying mechanisms. We established PF mouse models and human pleural mesothelial cell fibrosis in vitro by intraperitoneal injection of high-glucose peritoneal dialysis solution (PDS) or transforming growth factor-β1 (TGF-β1), and evaluated the effect of SM on peritoneal fibrosis in vivo and in vitro. We found that SM alleviated peritoneal dysfunction. Meanwhile, SM inhibited the expression of fibrotic markers (TGF-β1, collagen I, fibronectin) and restored the expression of E-cadherin, BMP-7 in PF mice and TGF-β1-treated Met-5A cells. Furthermore, SM markedly down-regulated the expression of TGF-β1, p-Smad2, and p-Smad3 and up-regulated the expression of smad7. In conclusion, these findings suggested that SM may be an efficient and novel therapy for the prevention of PF through inhibition of TGF-β/Smad signaling.

Simultaneous determination of multiple constituents, serum composition, and tissue distribution of Qingshen granule using ultra-high performance liquid chromatography-quadrupole-orbitrap high-resolution mass spectrometry

Qingshen granule, composed of 14 herbal drugs, is primarily used as the assistant therapy for chronic kidney disease. Qingshen granule chemical composition was complex, but its chemical constituents and the pharmacodynamic material basis remain unreported. Ultra-high-performance liquid chromatography (UHPLC)-quadrupole-orbitrap high-resolution mass spectrometry was applied to recognize the chemical constituents of Qingshen granule. The analysis was performed using the ACQUITY UHPLC BEH C18 column (2.1 × 50 mm, 1.7 μm) with acetonitrile-0.1% formic acid as the mobile phase for gradient elution. The data were collected using heated electrospray ionization in positive and negative ion modes. This study successfully applied the UPHLC-quadrupole-orbitrap high-resolution mass spectrometry technique with the Compound Discoverer 3.3 platform to analyze Qingshen granule chemical composition. A total of 127 and 42 chemical components were identified in Qingshen granule in vitro and in vivo, respectively. In the tissue distribution of Qingshen granule, 9, 10, 11, 10, and 18 prototype components were detected in the heart, liver, spleen, lungs, and kidneys, respectively. Qingshen granule chemical constituents were characterized rapidly for the first time in this study, laying a foundation for further research on the substance basis and quality control of Qingshen granule in treating chronic kidney disease.

Ferroptosis: A new mechanism of traditional Chinese medicine compounds for treating acute kidney injury

Acute kidney injury (AKI) is a major health concern owing to its high morbidity and mortality rates, to which there are no drugs or treatment methods, except for renal replacement therapy. Therefore, identifying novel therapeutic targets and drugs for treating AKI is urgent. Ferroptosis is an iron-dependent and lipid-peroxidation-driven regulatory form of cell death and is closely associated with the occurrence and development of AKI. Traditional Chinese medicine (TCM) has unique advantages in treating AKI due to its natural origin and efficacy. In this review, we summarize the mechanisms underlying ferroptosis and its role in AKI, and TCM compounds that play essential roles in the prevention and treatment of AKI by inhibiting ferroptosis. This review suggests ferroptosis as a potential therapeutic target for AKI, and that TCM compounds show broad prospects in the treatment of AKI by targeting ferroptosis.

Nephroprotective and nephrotoxic effects of Rhubarb and their molecular mechanisms

Rhubarb, in the form of a traditional Chinese medicine, is used in the treatment of chronic kidney disease (CKD). Previous studies have demonstrated that Rhubarb possesses a good nephroprotective effect, which primarily protects the kidneys from fibrosis, oxidation, inflammation, autophagy, and apoptosis. However, studies have shown that the long-term inappropriate use of Rhubarb may cause damage to renal function. Therefore, how to correctly understand and scientifically evaluate the pharmacodynamics and toxicity of Rhubarb with regard to CKD is a scientific question that urgently needs to be answered. In this review, we explain and illustrate how Rhubarb exerts its nephroprotective effect against CKD. We also describe the mechanisms of action that may cause its nephrotoxicity. Valuable and practical clinical guidance is proposed with regard to methods for mitigating the nephrotoxicity of Rhubarb.

Rheum officinale and Salvia miltiorrhiza inhibit renal fibrosis via miR-21/PTEN/Akt signaling pathway in vitro and in vivo

ETHNOPHARMACOLOGICAL RELEVANCE

As one of the main components of many famous Chinese herbal formulas, Rheum palmatum L. and Salvia miltiorhiza Bunge (RS) are extensively used to treat chronic kidney disease (CKD). RS has been proved to improve renal function and relieve renal fibrosis (RF), but the potential mechanism remains a mystery.

AIM OF THE STUDY

The purpose of this study is to determine whether microRNA-21 (miR-21) is associated with RF progression, as well as whether RS protects against RF through miR-21/PTEN/AKT signaling.

MATERIALS AND METHODS

(1) The rat model of RF was established using unilateral ureteral obstruction (UUO). After UUO surgery, miR-21 levels in plasma were detected by RT-PCR and RF scores were assessed by Masson's trichrome stain at days 3, 7, 14 and 21. The correlation analysis of the above two indexes was carried out by Spearman correlation analysis. (2) Human proximal tubular epithelial cells (HK-2) was transfected with miR-21 mimic and inhibitor, and then the levels of phosphatase and tensin homolog (PTEN) protein and mRNA were measured with Western blotting and RT-PCR, respectively. (3) TGF-β (10 ng/mL) was added into HK-2 cells to induce fibrosis, followed by the intervention of RS-containing rat serum. PTEN and protein kinase-B (Akt) phosphorylation, as well as the expression of PTEN protein in HK-2 cells, were assessed by RT-PCR, Western blotting and immunofluorescence. (4) The rat models of RF were prepared by UUO and treated with RS. Serum creatinine and urea nitrogen levels were measured. RF score was determined by Masson's trichrome stain. RT-PCR was used to determine the expression of miR-21, PTEN, and Akt mRNA. Western blotting was used to determine the expression of PTEN and Akt proteins.

RESULTS

A positive correlation was found between plasma miR-21 levels and RF scores of rats after UUO surgery at Days 3, 7, 14 and 21. It was confirmed that miR-21 targeted PTEN. RS drug-containing serum could rise the expression of PTEN and reduce Akt phosphorylation of HK-2 cells induced by TGF-β. Moreover, RS drug-containing serum could increase PTEN expression and reduce Akt phosphorylation induced by miR-21 mimic in HK-2 cells. The rats treated with RS had significantly decreased serum creatinine and urea nitrogen levels and a lower RF score. RS also decreased miR-21 and Akt expressions, increased PTEN expression of UUO rats.

CONCLUSION

There was a positive correlation between plasma miR-21 levels and RF scores. The inhibitory effect of RS on RF might be mediated by miR-21/PTEN/AKT signaling.

Rhein for treating diabetes mellitus: A pharmacological and mechanistic overview

With the extension of life expectancy and changes in lifestyle, the prevalence of diabetes mellitus is increasing worldwide. Rheum palmatum L. a natural botanical medicine, has been used for thousands of years to prevent and treat diabetes mellitus in Eastern countries. Rhein, the main active component of rhubarb, is a 1, 8-dihydroxy anthraquinone derivative. Previous studies have extensively explored the clinical application of rhein. However, a comprehensive review of the antidiabetic effects of rhein has not been conducted. This review summarizes studies published over the past decade on the antidiabetic effects of rhein, covering the biological characteristics of Rheum palmatum L. and the pharmacological effects and pharmacokinetic characteristics of rhein. The review demonstrates that rhein can prevent and treat diabetes mellitus by ameliorating insulin resistance, possess anti-inflammatory and anti-oxidative stress properties, and protect islet cells, thus providing a theoretical basis for the application of rhein as an antidiabetic agent.

Integration of Chinese Herbal Medicine into Routine Care Was Related to Lower Risk of Chronic Kidney Disease in Patients with Rheumatoid Arthritis: A Population-Based Nested Case-Control Study in Taiwan

Objective

Non-steroidal anti-inflammatory drugs (NSAIDs) are frequently used as the first-line agents for the symptomatic relief of rheumatoid arthritis (RA), but it may insidiously provoke the onset of renal diseases, especially chronic kidney disease (CKD). While Chinese herbal medicine (CHM) has become an increasingly popular adjunctive therapy among RA groups, there are currently no available data on the effect of CHM use towards risk of CKD. This study aimed to explore on a population-level whether CHM use decreases sequent CKD risk among them.

Methods

In this nested case-control study retrieved from the nationwide insurance database of Taiwan from 2000 to 2012, we looked at the association between CHM use and the likelihood of developing CKD, with a focus on usage intensity. Cases with CKD claims were defined and matched to one randomly selected control case. Conditional logistic regression was then applied to estimate odds ratio (OR) of CKD from CHM treatment measured before the index date. For each OR, we calculated a 95% confidence interval for CHM use relative to the matched control.

Results

This nested case-control study included 5464 patients with RA, where after matching comprised 2712 cases and 2712 controls. Among them, there were 706 and 1199 cases that ever received CHM treatment, respectively. After the adjustment, CHM use in RA individuals was related to a lower likelihood of CKD, with an adjusted OR of 0.49 (95% CI: 0.44-0.56). Additionally, a dose-dependent, reverse association was found between the cumulative duration of CHM use and risk of CKD.

Conclusion

Integrating CHM into conventional therapy may reduce the likelihood of developing CKD, which could be a reference in instituting novel preventive strategies to improve treatment outcomes and reduce related fatalities for RA subjects.

Intervention Mechanism of Niao Du Kang Mixture on the EMT Process of Peritoneal Fibrosis Based on the Wnt/β-Catenin Signaling Pathway

Methods

Quantification of 24-hour urine protein (24 h-Upro) and serum creatinine (Scr) levels was performed. The protein and mRNA expression levels of E-cadherin, α-SMA, collagen I, β-catenin, Wnt-1, and LEF-1 in peritoneal tissue were measured. In addition, the pathological morphology and ultrastructure of peritoneum were observed.

Results

After 5/6 nephrectomy + high glucose peritoneal dialysate + lipopolysaccharide (LPS) treatment, the Scr and 24 h-Upro of rats increased compared with normal rats, and the peritoneal tissue was damaged and thickened, showing fibrotic changes. Compared with the model group, the Scr and 24 h-Upro levels and the levels of E-cadherin, α-SMA, Wnt-1, collagen I, and LEF-1 protein expression in each Niao Du Kang mixture dosage group decreased. The protein expression of β-catenin and the mRNA expression of E-cadherin, α-SMA, Wnt-1, collagen I, β-catenin, and LEF-1 decreased in the high and medium Niao Du Kang mixture dose groups. Hematoxylin and eosin staining showed that the peritoneum of the rats was not only thicker in the model group than in the sham operation group (P < 0.01) but also accompanied by apparent inflammatory cell infiltration, tissue edema, and fibrosis. Compared with the model group, all the Niao Du Kang mixture groups demonstrated various degrees of mitigation in peritoneal thickness and fibrosis (P < 0.01). The strongest effect was observed in the medium-dose group. Transmission electron microscopy showed that the degree of injury of the peritoneal mesothelial cells was ranked as follows: model group > positive drug group > Niao Du Kang mixture high-dose group.

Conclusions

The Niao Du Kang mixture may effectively decrease the peritoneal thickness and fibrosis degree through its effect on the Wnt/β-catenin signaling pathway involved in EMT. The present study provides data that assist in elucidating the potential function of the Niao Du Kang mixture in treating or preventing PF.

Chrysophanol, a main anthraquinone from Rheum palmatum L. (rhubarb), protects against renal fibrosis by suppressing NKD2/NF-κB pathway

PURPOSE

Chronic kidney disease (CKD), characterized as renal dysfunction and multi-system damage, has become a serious public health problem with high prevalence and mortality. Rheum palmatum L. (rhubarb) is one of the most widely used Chinese herb with renal protective activity. However, the active components and underlying mechanisms of rhubarb remain unknown. In this work, we tried to explore the pharmacological mechanism of chrysophanol, a main anthraquinone from rhubarb, against CKD by in vivo and in vitro models.

STUDY DESIGN

The therapeutic effect of chrysophanol and its underlying mechanism were investigated using CKD mouse model induced by unilateral ureteral occlusion (UUO), and human kidney 2 (HK-2) cells stimulated by TGF-β1 in vivo.

METHODS

The impact of chrysophanol on renal function, inflammation, fibrosis of CKD mice were evaluated. Then, the protein expressions of FN1, collagen ɑI, α-SMA, NF-κB and naked keratinocyte homolog 2 (NKD2) were investigated. In vitro studies, the inhibition on inflammation and fibrogenesis by chrysophanol was further validated in TGF-β1-stimulated HK2 cells, and the regulation of chrysophanol on NKD2/NF-κB pathway was analyzed. Moreover, NKD2 was overexpressed in HK-2 cells to confirm the role of NKD2/NF-κB pathway in chrysophanol-mediated efficacy. Finally, the binding mode of chrysophanol with NKD2 was studied using in silico molecular docking and microscale thermophoresis (MST) assay.

RESULTS

Chrysophanol could significantly improve the kidney dysfunction, alleviate renal pathology, and reverse the elevated levels of renal fibrosis markers such as FN1, collagen ɑI and α-SMA. Furthermore, chrysophanol effectively inhibited TNF-α, IL-6, and IL-1β production, and suppressed NF-κB activation and NKD2 expression. The findings of in vitro study were consistent with those of animal expriment. Using NKD2-overexpressing HK-2 cells, we also demonstrated that overexpression of NKD2 significantly compromised the anti-fibrotic effects of chrysophanol. In addition, molecular docking and MST analysis revealed that NKD2 was a direct target of chrysophanol.

CONCLUSION

Together, our work demonstrated for the first time that chrysophanol could effectively ameliorate renal fibrosis by inhibiting NKD2/NF-κB pathway. Chrysophanol can potentially prevent CKD by suppressing renal NKD2 expression directly.

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.

The Protective Effect of Ursolic Acid on Unilateral Ureteral Obstruction in Rats by Activating the Nrf2/HO-1 Antioxidant Signaling Pathway

Renal interstitial fibrosis is a common pathological feature of a variety of kidney diseases that progress to end-stage renal disease. The excessive deposition of extracellular matrix (ECM) is a typical pathological change of renal interstitial fibrosis. The production of reactive oxygen species in renal tubules is an important factor leading to the development of renal interstitial fibrosis. Ursolic acid (UA) is a natural pentacyclic triterpene carboxylic acid compound widely found in plants. It has anti-inflammatory, antioxidant, and antitumor cell proliferation effects. It can reduce the development of fibrosis by inhibiting the oxidative stress response of the liver; there is currently no relevant research on whether UA can protect the renal interstitial fibrosis by resisting oxidative stress in the kidneys. In this study, our purpose is to investigate the effect of ursolic acid on renal interstitial fibrosis after unilateral ureteral obstruction (UUO) in rats and its related mechanisms. We established a UUO model by surgically ligating the right ureter of the rat and instilling UA preparation (40 mg/kg/d) through the stomach after the operation, once a day for 7 days. We found that UUO caused impaired renal function, increased pathological damage, increased renal interstitial fibrosis, increased apoptosis, increased oxidative stress damage, and decreased antioxidants. However, after UA preparations were given, the abovementioned damage was significantly improved. At the same time, we also found that UA preparations can significantly increase the relative expression of Nrf2/HO-1 signaling pathway in kidney tissue after UUO. In order to further verify whether the Nrf2/HO-1 signaling pathway is involved in the development of renal interstitial fibrosis, we injected zinc protoporphyrin (ZnPP, 45 umol/kg), a specific blocker of the Nrf2/HO-1 signaling pathway, into the intraperitoneal cavity after UUO in rats and before the gastric perfusion of ursolic acid preparations. Subsequently, we observed that the protective effect of UA on renal interstitial fibrosis after UUO in rats was reversed. Combining all the research results, we proved that UA has a protective effect on renal interstitial fibrosis after UUO in rats, which may be achieved by activating the Nrf2/HO-1 signaling pathway.

Natural products: potential drugs for the treatment of renal fibrosis

With the increasing prevalence and mortality, chronic kidney disease (CKD) has become a world public health problem. As the primary pathological manifestation in CKD, renal fibrosis is often used as a critical target for the treatment of CKD and inhibits the progression of CKD to end-stage renal disease (ESRD). As a potential drug, natural products have been confirmed to have the potential as a routine or supplementary therapy for chronic kidney disease, which may target renal fibrosis and act through various pharmacological activities such as anti-inflammatory and anti-oxidation of natural products. This article briefly introduces the pathological mechanism of renal fibrosis and systematically summarizes the latest research on the treatment of renal fibrosis with natural products of Chinese herbal medicines.

TGF-β/Smad Signaling Pathway in Tubulointerstitial Fibrosis

Chronic kidney disease (CKD) was a major public health problem worldwide. Renal fibrosis, especially tubulointerstitial fibrosis, is final manifestation of CKD. Many studies have demonstrated that TGF-β/Smad signaling pathway plays a crucial role in renal fibrosis. Therefore, targeted inhibition of TGF-β/Smad signaling pathway can be used as a potential therapeutic measure for tubulointerstitial fibrosis. At present, a variety of targeting TGF-β1 and its downstream Smad proteins have attracted attention. Natural products used as potential therapeutic strategies for tubulointerstitial fibrosis have the characteristics of acting on multiple targets by multiple components and few side effects. With the continuous research and technique development, more and more molecular mechanisms of natural products have been revealed, and there are many natural products that inhibited tubulointerstitial fibrosis via TGF-β/Smad signaling pathway. This review summarized the role of TGF-β/Smad signaling pathway in tubulointerstitial fibrosis and natural products against tubulointerstitial fibrosis by targeting TGF-β/Smad signaling pathway. Additionally, many challenges and opportunities are presented for inhibiting renal fibrosis in the future.

Green tea peptides ameliorate diabetic nephropathy by inhibiting the TGF-β/Smad signaling pathway in mice

Diabetic nephropathy (DN) is the most important cause of middle and late-stage chronic kidney disease. Green tea polypeptides are extracted from tea pomace, and exhibit various pharmacological effects. In this study, we analyzed the reno-protective effects of green tea peptides in diabetic db/db mice, and explored the underlying mechanisms. Peptide treatment for 5 weeks significantly reduced the blood glucose levels and other indices of diabetes, and alleviated renal injury measured in terms of blood creatinine, urea nitrogen and urinary albumin/urinary creatinine levels. Mechanistically, the green tea peptides downregulated p-Smad2/3, α-SMA, ZO-1 and vimentin proteins in the kidney tissues, and elevated Smad7. Thus, green tea peptides inhibited the deposition of ECM proteins by suppressing excessive activation of the TGF-β/Smad signaling pathway and reducing fibronectin levels. On the other hand, tea peptides ameliorated renal injury by inhibiting the production of inflammatory factors (iNOS and TNF-α) by suppressing the NF-κB signaling pathway. In addition, we confirmed the inhibitory effect of green tea peptides on the TGF-β/Smad signaling pathway in TGF-β1-stimulated HK-2 cells. Therefore, tea peptides can be considered as an effective candidate for alleviating DN.

Nur77 ameliorates age-related renal tubulointerstitial fibrosis by suppressing the TGF-β/Smads signaling pathway

Nerve growth factor-induced gene B (Nur77) has been shown to ameliorate several biological processes in chronic diseases, including inflammatory response, cellular proliferation, and metabolism. Chronic kidney disease (CKD) is characterized by tubulointerstitial fibrosis for which no targeted therapies are available as yet. In this study, we performed in vivo and in vitro experiments to demonstrate that Nur77 targets fibrosis signals and attenuates renal tubulointerstitial fibrosis during the aging process. We observed that the TGF-β/Smads signal pathway was significantly suppressed by Nur77, suggesting that Nur77 controlled the activation of key steps in TGF-β/Smads signaling. We further showed that Nur77 interacted with Smad7, the main repressor of nuclear translocation of Smad2/3, and stabilized Smad7 protein homeostasis. Nur77 deficiency resulted in Smad7 degradation, aggravating Smad2/3 phosphorylation, and promoting transcription of its downstream target genes, ACTA2 and collagen I. Our findings demonstrate that Nur77 is a potential therapeutic target for age-related kidney diseases including CKD. Maintenance of Nur77 may be an effective strategy for blocking renal tubulointerstitial fibrosis and improving renal function in the elderly.

Shenkang Injection and Its Three Anthraquinones Ameliorates Renal Fibrosis by Simultaneous Targeting IƙB/NF-ƙB and Keap1/Nrf2 Signaling Pathways

Oxidative stress and inflammation are important and critical mediators in the development and progression of chronic kidney disease (CKD) and its complications. Shenkang injection (SKI) has been widely used to treat patients with CKD. Although the anti-oxidative and anti-inflammatory activity was involved in SKI against CKD, its bioactive components and underlying mechanism remain enigmatic. A rat model of adenine-induced chronic renal failure (CRF) is associated with, and largely driven by, oxidative stress and inflammation. Hence, we identified the anti-oxidative and anti-inflammatory components of SKI and further revealed their underlying mechanism in the adenine-induced CRF rats. Compared with control rats, the levels of creatinine, urea, uric acid, total cholesterol, triglyceride, and low-density lipoprotein cholesterol in serum were significantly increased in the adenine-induced CRF rats. However, treatment with SKI and its three anthraquinones including chrysophanol, emodin, and rhein could reverse these aberrant changes. They could significantly inhibit pro-fibrotic protein expressions including collagen I, α-SMA, fibronectin, and vimentin in the kidney tissues of the adenine-induced CRF rats. Of note, SKI and rhein showed the stronger inhibitory effect on these pro-fibrotic protein expressions than chrysophanol and emodin. Furthermore, they could improve dysregulation of IƙB/NF-ƙB and Keap1/Nrf2 signaling pathways. Chrysophanol and emodin showed the stronger inhibitory effect on the NF-κB p65 protein expression than SKI and rhein. Rhein showed the strongest inhibitory effect on p65 downstream target gene products including NAD(P)H oxidase subunits (p47phox, p67phox, and gp91phox) and COX-2, MCP-1, iNOS, and 12-LO in the kidney tissues. However, SKI and rhein showed the stronger inhibitory effect on the significantly downregulated anti-inflammatory and anti-oxidative protein expression nuclear Nrf2 and its target gene products including HO-1, catalase, GCLC, and NQO1 in the Keap1/Nrf2 signaling pathway than chrysophanol and emodin. This study first demonstrated that SKI and its major components protected against renal fibrosis by inhibiting oxidative stress and inflammation via simultaneous targeting IƙB/NF-ƙB and Keap1/Nrf2 signaling pathways, which illuminated the potential molecular mechanism of anti-oxidative and anti-inflammatory effects of SKI.

Drug-containing serum of rhubarb-astragalus capsule inhibits the epithelial-mesenchymal transformation of HK-2 by downregulating TGF-β1/p38MAPK/Smad2/3 pathway

ETHNOPHARMACOLOGICAL RELEVANCE

Rheum palmatum L; Astragalus membranaceus (Fisch.), is referred to as 'Dahuang, Huangqi' in China. As an important medicinal plant, the rhizome of rhubarb and astragalus is traditionally used in the treatment of kidney diseases associated with renal failure, inflammation and tumors.

AIM OF THE STUDY

This study aimed to investigate the effect of a drug-containing serum of rhubarb-astragalus capsules (composed of rhubarb and astragalus) and to elucidate its mechanism in the epithelial-mesenchymal transformation of renal tubular epithelial cells.

MATERIALS AND METHODS

Epithelial-mesenchymal transformation (EMT) of HK-2 cells was induced by TGF-β1, and rhubarb-astragalus and losartan drug-containing serum from rats, as well as SB203580 (a specific inhibitor of p38 MAPK), were used. High-performance liquid chromatography analysis was performed to determine the main components of the drug-containing serum of rhubarb-astragalus from rats. Western blotting and immunofluorescence analysis were used to determine the levels of protein expression, and real-time quantitative PCR analysis was used to detect the levels of gene expression.

RESULTS

The drug-containing serum of rhubarb-astragalus contained emodin (0.36 μg/ml) and danthraquinone (0.96 μg/ml). Rhubarb-astragalus significantly decreased the protein expression levels of α-SMA, FN, vimentin and N-cadherin in HK-2 cells that were increased by TGF-β1, while it significantly increased the E-cadherin protein expression level that was decreased by TGF-β1. Rhubarb-astragalus also significantly decreased the protein expression levels of TGF-β1 and p38 MAPK and the mRNA expression levels of α-SMA, vimentin, TGF-β1, p38 MAPK, Smad2 and Smad3 in HK-2 cells that were increased by TGF-β1. It is worth noting that SB203580 (a p38 MAPK inhibitor) had similar effects as rhubarb-astragalus in this study.

CONCLUSION

The drug-containing serum of rhubarb-astragalus can inhibit EMT in HK-2 cells by downregulating the TGF-β1/p38 MAPK/Smad2/3 pathway.

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.

Transforming Growth Factor-β1/Smad Signaling in Glomerulonephritis and Its Association with Progression to Chronic Kidney Disease

INTRODUCTION

Transforming growth factor-β1 (TGF-β1) is a multifunctional cytokine, with diverse roles in fibrosis and inflammation, which acts through Smad signaling in renal pathology. We intended to investigate the expression of TGF-β/Smad signaling in glomerulonephritis (GN) and to assess its role as risk factor for progression to chronic kidney disease (CKD).

METHODS

We evaluated the immunohistochemical expression of TGF-β1, phosphorylated Smad3 (pSmad3), and Smad7 semiquantitatively and quantitatively using computerized image analysis program in different compartments of 50 renal biopsies with GN, and the results were statistically analyzed with clinicopathological parameters. We also examined the associations among their expressions, the impact of their co-expression, and their role in progression to CKD.

RESULTS

TGF-β1 expression correlated positively with segmental glomerulosclerosis (p= 0.025) and creatinine level at diagnosis (p = 0.002), while pSmad3 expression with interstitial inflammation (p = 0.024). In glomerulus, concomitant expressions of high Smad7 and medium pSmad3 were observed to be correlated with renal inflammation, such as cellular crescent (p = 0.011), intense interstitial inflammation (p = 0.029), and lower serum complement (C) 3 (p = 0.028) and C4 (p = 0.029). We also reported a significant association between pSmad3 expression in glomerular endothelial cells of proliferative GN (p = 0.045) and in podocytes of nonproliferative GN (p = 0.005). Finally, on multivariate Cox-regression analysis, TGF-β1 expression (hazard ratio = 6.078; 95% confidence interval: 1.168-31.627; p = 0.032) was emerged as independent predictor for CKD.

DISCUSSION/CONCLUSION

TGF-β1/Smad signaling is upregulated with specific characteristics in different forms of GN. TGF-β1 expression is indicated as independent risk factor for progression to CKD, while specific co-expression pattern of pSmad3 and Smad7 in glomerulus is correlated with renal inflammation.

The Health Benefits of Emodin, a Natural Anthraquinone Derived from Rhubarb-A Summary Update

Emodin (6-methyl-1,3,8-trihydroxyanthraquinone) is a naturally occurring anthraquinone derivative found in roots and leaves of various plants, fungi and lichens. For a long time it has been used in traditional Chinese medicine as an active ingredient in herbs. Among other sources, it is isolated from the rhubarb Rheum palmatum or tuber fleece-flower Polygonam multiflorum. Emodin has a wide range of biological activities, including diuretic, antibacterial, antiulcer, anti-inflammatory, anticancer and antinociceptive. According to the most recent studies, emodin acts as an antimalarial and antiallergic agent, and can also reverse resistance to chemotherapy. In the present work the potential therapeutic role of emodin in treatment of inflammatory diseases, cancers and microbial infections is analysed.

Mechanisms and Efficacy of Chinese Herbal Medicines in Chronic Kidney Disease

As the current treatment of chronic kidney disease (CKD) is limited, it is necessary to seek more effective and safer treatment methods, such as Chinese herbal medicines (CHMs). In order to clarify the modern theoretical basis and molecular mechanisms of CHMs, we reviewed the knowledge based on publications in peer-reviewed English-language journals, focusing on the anti-inflammatory, antioxidative, anti-apoptotic, autophagy-mediated and antifibrotic effects of CHMs commonly used in kidney disease. We also discussed recently published clinical trials and meta-analyses in this field. Based on recent studies regarding the mechanisms of kidney disease in vivo and in vitro, CHMs have anti-inflammatory, antioxidative, anti-apoptotic, autophagy-mediated, and antifibrotic effects. Several well-designed randomized controlled trials (RCTs) and meta-analyses demonstrated that the use of CHMs as an adjuvant to conventional medicines may benefit patients with CKD. Unknown active ingredients, low quality and small sample sizes of some clinical trials, and the safety of CHMs have restricted the development of CHMs. CHMs is a potential method in the treatment of CKD. Further study on the mechanism and well-conducted RCTs are urgently needed to evaluate the efficacy and safety of CHMs.

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.

Chrysophanol Relieves Cisplatin-Induced Nephrotoxicity via Concomitant Inhibition of Oxidative Stress, Apoptosis, and Inflammation

Cisplatin (CDDP) is one of the most frequently prescribed chemotherapy medications. However, its nephrotoxicity which often leads to acute kidney injury (AKI), greatly limits its clinical application. Chrysophanol (CHR), a mainly active anthraquinone ingredient, possesses various biological and pharmacological activities. In this study, we aimed to investigate the underlying protective mechanisms of CHR against CDDP-induced AKI (CDDP-AKI) using C57BL/6 mouse and human proximal tubule epithelial cells. In vivo, we found that pre-treatment with CHR greatly relieved CDDP-AKI and improved the kidney function and morphology. The mechanistic studies indicated that it might alleviate CDDP-AKI by inhibiting oxidative stress, apoptosis, and IKKβ/IκBα/p65/transcription factor nuclear kappa B (NF-κB) inflammation signaling pathway induced by CDDP. Moreover, we found that the cell viability of HK2 cells reduced by CDDP was partially rescued by CHR pre-incubation. Flow cytometry results further indicated that CHR pre-incubation suppressed CDDP induced cellular reactive oxygen species (ROS) generation and inhibited cell apoptosis in a dose-dependent manner. In summary, our results suggested that CHR might be a novel therapy for CDDP-induced AKI.

Chrysophanol Inhibits the Progression of Diabetic Nephropathy via Inactivation of TGF-β Pathway

Background

Diabetic nephropathy (DN) is a common form of diabetic complication which threatens the health of patients with diabetes. It has been reported that chrysophanol (CHR) can alleviate the progression of diabetes; however, the role of CHR in DN remains unclear.

Methods

To mimic DN in vitro, human podocytes (AB8/13 cells) were treated with high glucose (HG). Meanwhile, Western blot was performed to detect protein expressions. CCK-8 assay was used to test cell viability and cell proliferation was detected by Ki-67 staining. In addition, flow cytometry was performed to investigate cell apoptosis and cycle and cell migration was tested by transwell assay. Moreover, in vivo model of DN was established to detect the effect of CHR on DN in vivo.

Results

HG-induced AB8/13 cell growth inhibition was significantly rescued by CHR. In addition, HG notably promoted the migration of AB8/13 cells, while this phenomenon was obviously reversed by CHR. Moreover, CHR inhibited the progression of DN via inactivation of TGF-β/EMT axis. Furthermore, CHR alleviated the symptom of DN in vivo.

Conclusion

CHR significantly alleviated the progression of DN via inactivation of TGF-β/EMT signaling in vitro and in vivo. Our findings were helpful to uncover the mechanism by which CHR regulates DN, as well as inspire the development of novel therapy against DN.

Inhibition of proliferation-linked signaling cascades with atractylenolide I reduces myofibroblastic phenotype and renal fibrosis

Renal fibrosis is a frequent axis contributing to the occurrence of end-stage nephropathy. Previously, it has been reported that atractylenolide Ⅰ (ATL-1), a natural compound extracted from Atractylodes macrocephala, has anti-cancer and antioxidant effects. However, the renal anti-fibrotic effects of action remain unclear. In this study, the anti-fibrotic effects of ATL-1 were examined in fibroblasts, tubular epithelial cells (TECs) triggered by TGF-β1 in vitro, and using a unilateral ureteral obstruction (UUO) mouse model in vivo. We found that ATL-1 represses the myofibroblastic phenotype and fibrosis development in UUO kidneys by targeting the fibroblast-myofibroblast differentiation (FMD), as well as epithelial-mesenchymal transition (EMT). The anti-fibrotic effects of ATL-1 were associated with reduced cell growth in the interstitium and tubules, leading to suppression of the proliferation-linked cascades activity consisting of JAK2/STAT3, PI3K/Akt, p38 MAPK, and Wnt/β-catenin pathways. Besides, ATL-1 treatment repressed TGF-β1-triggered FMD and the myofibroblastic phenotype in fibroblasts by antagonizing the activation of proliferation-linked cascades. Likewise, TGF-β1-triggered excessive activation of the proliferation-linked signaling in TECs triggered EMT. The myofibroblastic phenotype was repressed by ATL-1. The anti-fibrotic and anti-proliferative effects of ATL-1 were linked to the inactivation of Smad2/3 signaling, partially reversing FMD, as well as EMT and the repression of the myofibroblastic phenotype. Thus, the inhibition of myofibroblastic phenotype and fibrosis development in vivo and in vitro through proliferation-linked cascades of ATL-1 makes it a prospective therapeutic bio-agent to prevent renal fibrosis.