The molecular mechanism of rhein in diabetic nephropathy

PS-MPs promotes the progression of inflammation and fibrosis in diabetic nephropathy through NLRP3/Caspase-1 and TGF-β1/Smad2/3 signaling pathways

BACKGROUND

Diabetic nephropathy (DN) is a prevalent chronic microvascular complication of diabetes and the leading cause of end-stage renal disease (ESRD). Understanding the progressive etiology of DN is critical for the development of effective health policies and interventions. Recent research indicated that polystyrene microplastics (PS-MPs) contaminate our diets and accumulate in various organs, including the liver, kidneys, and muscles.

METHODS

In this study, ten-week-old db/db mice and db/m mice were fed. Besides, db/db mice were divided into two groups: PS-MPs group (oral administration of 0.5 µm PS-MPs) and an H2O group, and they were fed for three months. A type II diabetes model was established using db/db mice to investigate the effects of PS-MPs on body weight, blood glucose level, renal function, and renal fibrosis.

RESULTS

The results demonstrated that PS-MPs significantly exacerbated various biochemical indicators of renal tissue damage, including fasting blood glucose, serum creatinine, blood urea nitrogen, and blood uric acid. Additionally, PS-MPs worsened the pathological alterations and degree of fibrosis in renal tissue. An increased oxidative stress state and elevated levels of inflammatory cytokines, such as tumor necrosis factor-α (TNF-α), interleukin-1β (IL-1β), and monocyte chemoattractant protein-1 (MCP-1) were identified. Furthermore, PS-MPs significantly enhanced renal fibrosis by inhibiting the transition from epithelial cells to mesenchymal cells, specifically through the inhibition of the TGF-β/Smad signaling pathway. The expression levels of NOD-like receptor protein 3 (NLRP3), apoptosis-associated speck-like protein containing a CARD (ASC), Caspase-1, and cleaved Caspase-1, which are inflammasome proteins, were significantly elevated in the PS-MPs group.

CONCLUSION

The findings suggested that PS-MPs could aggravate kidney injury and renal fibrosis in db/db mice by promoting NLRP3/Caspase-1 and TGF-β1/Smads signaling pathways. These findings had implications for elucidating the role of PS-MPs in DN progression, underscoring the necessity for additional research and public health interventions.

Comparative pharmacokinetic analysis of six major bioactive constituents using UPLC-MS/MS in samples isolated from normal and diabetic nephropathy rats after oral administration of Gushen Jiedu capsule

Berberine, palmatine, physcion, rhein, calycosin-7-O-glucoside, and ferulic acid are six major active consituents that are present in Gushen Jiedu capsule (GSJD) extracts. The aim of this study was to determine the pharmacokinetics of the six active consituents in vivo by a rapid, sensitive, and precise UPLC-MS/MS method, which were compared between normal and diabetic nephropathy (DN) rats. Good separation of the target analytes and internal standards (ketoprofen and puerarin) was obtained on a Waters BEH C18 UPLC column with a mobile phase of 0.1 % formic acid acetonitrile-0.1 % formic acid water. All the calibration curves showed good linearity with a regression coefficient (r2) of ≥ 0.9908. The lower limits of quantification (LLOQ) for berberine, palmatine, physcion, rhein, calycosin-7-O-glucoside, and ferulic acid were 20, 2.5, 20, 20, 2.5, and 2.5 ng/mL, respectively. The relative standard deviations (RSDs) of intra-day and inter-day precision were all within 12.66 %, and the relative errors of intra-day and inter-day accuracy ranged from - 15.00 to 14.93 %. Good extraction recovery and matrix effects were obtained. The stability study confirmed the stability of the six analytes (RSD < 15 %). Finally, the data showed that the pharmacokinetic parameters (especially CLz/F, AUC and Tmax) of the six target analytes in DN rats were significantly different from those in normal rats. PK studies under pathological conditions could provide new thoughts to elucidate the underlying mechanism of GSJD and promote the clinical development of GSJD to treat DN.

Rhein protects retinal Müller cells from high glucose-induced injury via activating the AMPK/Sirt1/PGC-1α pathway

Oxidative stress, inflammation and apoptosis are important pathogenic factors of diabetic retinopathy (DR). In the current study, we aimed to evaluate the potential role of Rhein, a natural anthraquinone compound found in rhubarb, in high glucose (HG)-induced Müller cells (MIO-M1). Cell Counting Kit‑8 assay, TUNEL assay, Western blot analysis, Reverse transcription quantitative polymerase chain reaction (RT-qPCR), and ELISA were conducted to assess the effects of Rhein on Müller cells. Additionally, the EX-527, an Sirt1 inhibitor, was used to study whether the effects of Rhein, on HG-induced Müller cells were mediated by activation of the Sirt1 signaling pathway. Our data showed that Rhein improved cell viability of HG-induced Müller cells. Rhein reduced the ROS and MDA production and increased the activities of SOD and CAT in Müller cells in response to HG stimulation. Rhein decreased the production of VEGF, IL-1β, IL-6 and TNF-α. Moreover, Rhein attenuated HG-induced apoptosis, evidenced by increase in Bcl-2 level and decreases in the Bax, caspase-3 expression. It was also found that EX-527 counteracted Rhein-mediated anti-inflammatory, antioxidant and anti-apoptosis effects on Müller cells. The protein levels of p-AMPK and PGC-1α were also upregulated by Rhein. In conclusion, these findings support that Rhein may ameliorate HG-induced inflammation, oxidative stress, apoptosis and protect against mitochondrial dysfunction by the activation of the AMPK/Sirt1/PGC-1α signaling pathway.

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.

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.

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.

Emerging Mechanisms and Targeted Therapy of Pyroptosis in Central Nervous System Trauma

Cell death can occur in different modes, ferroptosis, pyroptosis, apoptosis, and necroptosis. Recent studies have shown that pyroptosis can be effectively regulated and that like necroptosis, pyroptosis has been regarded as a type of programmed cell death. The mechanism of its occurrence can be divided into canonical inflammasome-induced pyroptosis and noncanonical inflammasome-induced pyroptosis. In the past research, pyroptosis has been shown to be closely related to various diseases, such as tumors, neurodegenerative diseases, and central nervous system trauma, and studies have pointed out that in central nervous system trauma, pyroptosis is activated. Furthermore, these studies have shown that the inhibition of pyroptosis can play a role in protecting nerve function. In this review, we summarized the mechanisms of pyroptosis, introduce treatment strategies for targeted pyroptosis in central nervous system trauma, and proposed some issues of targeted pyroptosis in the treatment of central nervous system injury.

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.

Color-reflected chemical regulations of the scorched rhubarb (Rhei Radix et Rhizoma) revealed by the integration analysis of visible spectrophotometry, Fourier transform infrared spectroscopy and high performance liquid chromatography

Rhubarb has been used as herbal purgative with a worldwide long history. In traditional Chinese medicine, rhubarb can be stir-baked to scorch to eliminate the purgative function when it is a side effect. Under-scorched rhubarb still has the side effect of purgative, while over-scorched rhubarb can lose all bioactivities. Empirically, the degree of scorching is determined by manual observation of the rhubarb color. In order to find the reasonable and objective scorching endpoint criteria, visible spectrophotometry, FTIR spectroscopy and HPLC were used to reveal the color-reflected chemical changes. It was found that the blackening of rhubarb corresponded to the elimination of combined anthraquinones and the rise-fall inflection of free anthraquinones. The scorching endpoint criteria should include the upper limit for combined anthraquinones to avoid under-scorch and the lower limit for free anthraquinones to avoid over-scorch. Visible and FTIR spectroscopy can be process analytical techniques for the rhubarb scorching.

Rhein Derivatives, A Promising Pivot?

Rhein, an anthraquinone derivative, has been employed widely, especially for the treatment of intractable diseases like diabetic nephropathy, arthritis, and cancer in a unique action mechanism. In the last decades, considerable efforts have been made in structural modification of rhein. This paper reviewed patents on pharmacological activity and therapeutic application of rhein and its derivatives from 1978 to 2018. Particularly, an analysis of patents was made, with the top 10 most valuable patents presented, and the interpretation of the legal status of patents was given. Given the properties of superior pharmacological activity, rich resources, cheap price, low toxicity, and mature extraction process, it is believed that an in-depth investigation on rhein and its derivatives is worth trying.

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.

Rhein protects 5/6 nephrectomized rat against renal injury by reducing inflammation via NF-κB signaling

BACKGROUND/AIMS

Inflammation is well known to play a pivotal role in renal injury. Rhein is a major component of the medicinal Rhubarb. The aim of this study was to investigate whether Rhein protects against renal injury and explore its underlying mechanism.

METHODS

5/6 nephrectomization (5/6 Nx) was operated on Sprague-Dawley rats. Human kidney tubular epithelial (HK-2) cells were treated with lipopolysaccharide (LPS). The level of blood urea nitrogen (BUN) and serum creatinine (SCr) was examined. Kidney tissues were stained with hematoxylin and eosin to check the morphology. The cell viability was examined. The levels of cytokines and chemokines were measured by ELISA kit. The protein expression was determined by western blot.

RESULTS

Rhein significantly decreased SCr and BUN levels in 5/6 Nx rat. The morphologic findings indicated noteworthy amelioration of the damaged renal tissue in Rhein-treated rats. Rhein significantly protects HK-2 cells from LPS-mediated apoptosis. The productions of inflammatory signaling molecules (TNF-α, IL-6 and MCP-1) were inhibited by Rhein. LPS-induced NF-κB activation was also attenuated by Rhein via blocking its nuclear translocation by inhibiting phosphorylation of IκBα.

CONCLUSION

These findings provide evidence that Rhein protect against renal injury, and NF-κB signaling pathway is involved in this protective effect.

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.

Rhein Protects Against Neurological Deficits After Traumatic Brain Injury in Mice via Inhibiting Neuronal Pyroptosis

Neurological dysfunction provoked by traumatic brain injury (TBI) makes a huge impact on individual learning ability, memory level, social participation, and quality of life. Pyroptosis, the caspase-1-dependent cell death, which is associated with the release of numerous pro-inflammatory factors, plays a major role in the pathological process after TBI. Inhibition of pyroptosis has been shown to be an attractive strategy for the treatment of various neurological disorders. Here, we found that Rhein, an anthraquinone derived from the medicinal plant rhubarb, attenuated TBI-induced upregulation of pro-inflammatory cytokines, blood lactate dehydrogenase (LDH), and pyroptosis-related proteins, as well as reduced neurological dysfunction in a mouse TBI model. Consistently, Rhein inhibitd equiaxial stretch-induced neuron pyroptosis, LDH release, and upregulation of pro-inflammatory factors in vitro. Thus, our study suggested that Rhein protected against neurological deficits after TBI via inhibiting neuronal pyroptosis.

Renoprotective effects of Gushen Jiedu capsule on diabetic nephropathy in rats

Gushen Jiedu capsule (GSJD) is a formula that has been widely used in traditional Chinese medicine for the prevention and treatment of diabetic nephropathy (DN). However, the mechanism underlying the protective effects of GSJD on DN is still unclear. This study was performed to clarify the therapeutic effects of GSJD on DN and its underlying mechanisms. High-fat diet- and streptozotocin-induced DN rats were treated with or without GSJD suspension by gavage for 8 weeks, and biochemical changes in blood and urine were analysed. Kidneys were isolated for histological, TUNEL and Western blot analysis. Compared to the DN group, the GSJD-treated groups exhibited decreased urinary albumin, ameliorated renal dysfunction, including serum creatinine and blood urea nitrogen, and attenuated total cholesterol, triglyceride and total protein levels. However, there were no significant effects of GSJD on body weight, fasting blood glucose or albuminuria. Histology showed that GSJD could retard the progression of DN and decrease the apoptosis rate from 52% to less than 20%. Western blot analysis showed that GSJD could regulate the mitochondrial apoptotic pathway by downregulating the expression of Bax and upregulating the expression of BCL-2 in the kidneys of DN rats. Moreover, the Akt pathway, an upstream signalling pathway of the BCL-2 family, was also ameliorated by GSJD. Further, the podocyte foot process markers podocin and nephrin were upregulated by GSJD in DN rats. This study demonstrated that GSJD might play a renoprotective role by inhibiting apoptosis and regulating the mitochondrial apoptotic and Akt pathways during pathological changes in DN.

Luo Tong formula attenuates retinal inflammation in diabetic rats via inhibition of the p38MAPK/NF-κB pathway

Background

Diabetic retinopathy (DR) is a serious microvascular complication of diabetes and remains the leading cause of blindness in adults. Retinal inflammation is playing a crucial role in the development of DR, and targeting inflammatory mediators is a promising strategy for controlling DR. Here, we investigated compound Chinese medicine Luo Tong formula (LTF) alleviated retinal inflammatory responses in a STZ-induced diabetic rat model.

Methods

Sprague–Dawley rats were divided into four groups: control, streptozotocin-induced diabetic, LTF-treated diabetic, and calcium dobesilate (CaD)-treated diabetic rats. Blood samples were collected for blood glucose examination. Hematoxylin–eosin and periodic acid-Schiff staining were conducted for light microscopy observations. Retinal cell apoptosis was detected using the TUNEL assay. Proteins expression was quantified by Western blotting and/or immunohistochemistry, and gene expression was assessed by real-time PCR.

Results

Diabetic rats showed significant increases in the expression of tumor necrosis factor α (TNF-α), interleukin-1β (IL-1β), monocyte chemotactic protein-1 (MCP-1), intercellular adhesion molecule-1 (ICAM-1), nuclear factor-κB (NF-κB), and the phospho-p38 mitogen-activated protein kinase (p-p38-MAPK)/p38 MAPK ratio compared to control rats. LTF treatment significantly improved both retinal and pancreatic pathological injury, LTF treatment also inhibited inducible the p-p38 MAPK/p38 MAPK ratio and NF-κB activation and decreased the subsequent induction of the retinal expression of proinflammatory mediators TNF-α, IL-1β, MCP-1 and ICAM-1 compared to diabetic rats. LTF also exhibited a protective effect on islet function.

Conclusions

LTF before the onset of DR can alleviate retinal pathological injury, LTF may play an anti-inflammatory role by inhibiting p38-MAPK and then inhibiting NF-κB pathway. But further studies are needed to confirm this conclusion.

Trial registration This is an animal experiment, trial registration is not necessary.

A Significant Association Between Rhein and Diabetic Nephropathy in Animals: A Systematic Review and Meta-Analysis

Background: Rhein is considered to have beneficial influence on diabetic nephropathy. Animal experiments suggested that the mechanisms of rhein against diabetic nephropathy may involve many processes, but the credibility of the evidence is unclear. Therefore, we conducted systematic review and meta-analysis of pre-clinical animal data to assess the current evidence for rhein effects and mechanisms in treating diabetic nephropathy.

Methods: The databases of PubMed, EMBASE, Web of Science, China National Knowledge Infrastructure, VIP information database, Wanfang Data Information Site, and Chinese Biomedical Literature were searched for this review. SYRCLE’s risk of bias tool for animal studies was applied to assess the methodological quality of studies. A meta-analysis was performed according to the Cochrane Handbook for Systematic Reviews of Interventions by using RevMan 5.3 and STATA/SE 12.0 software. This study was registered with PROSPERO, number CRD42018105220.

Results: Twenty-five studies involving 537 animals were included. There was significant association of rhein with levels of blood glucose (P < 0.05), serum creatinine (Scr) (P < 0.05), urine protein (P < 0.05), kidney tubules injury index (P < 0.05), relative area of kidney collagen (P < 0.05), transforming growth factor-β₁ (P < 0.05), malondialdehyde (P < 0.05), and superoxide dismutase (P < 0.05) compared with that in the control group. No significant association between rhein and endothelin (P > 0.05) was found. Subgroup analysis showed that the hypoglycemic effect of rhein on type 2 diabetic nephropathy was better than on type 1 diabetic nephropathy (P < 0.05).

Conclusions: These findings suggested that rhein has beneficial effects on animal models of diabetic nephropathy, and that the mechanisms are mostly involved with ameliorating levels of TGF-β₁, renal fibrosis, metabolism, and oxidative stress status. However, some factors such as possible publication bias, methodological quality, and sample size may affect the accuracy of positive findings. These limitations suggested that a cautious interpretation of the positive results of this systematic review and meta-analysis is necessary. Therefore, high methodological quality and well-reported animal experiments are needed in future research.

Kidney-targeted rhein-loaded liponanoparticles for diabetic nephropathy therapy via size control and enhancement of renal cellular uptake

The optimization of nanoparticle size for passing through glomerular filtration membrane, inefficient renal cellular uptake and rapid urinary excretion of nanoparticles are the major obstacles for renal disease treatment via a nanoparticle delivery system. Herein, we propose a concept of a two-step nanoparticular cascade of size control and enhancement of renal cellular uptake to overcome the renal delivery obstacles. Methods: We prepared kidney-targeted rhein (RH)-loaded liponanoparticles (KLPPR) with a yolk-shell structure composed by polycaprolactone-polyethyleneimine (PCL-PEI)-based cores and kidney targeting peptide (KTP)-modified lipid layers. The KLPPR size within the range of 30 ~ 80 nm allowed KLPPR distribute into kidney by passing through the glomerular filtration membrane and the KTP (sequence: CSAVPLC) decoration promoted the renal cellular uptake and endocytosis via a non-lysosomal pathway. Results: The KLPPR had an average size of 59.5±6.2 nm and exhibited high RH loading, sustained release, good stability and biocompatibility, rapid cellular uptake in HK-2 cells. In addition, intravenous administration of KLPPR resulted in excellent kidney-targeted distribution and low urinary excretion in mice with streptozocin-induced diabetic nephropathy (DN), lowered the parameters of urea nitrogen, serum creatinine and kidney index, as well as facilitated the recovery of renal physiological function in improving the levels of urinary creatinine and the creatinine clearance rate by suppressing secretion and accumulation of fibronectin and TGF-β1. Conclusion: Definitely, KLPPR were able to target the diseased kidney and improve the therapeutic effect of RH on DN by exploiting the two-step nanoparticular cascade of size control and enhancement of cellular uptake. This study offers a promising strategy for renal diseases treatment using liponanoparticle delivery system.

Pharmacological properties of Rheum turkestanicum Janisch

Medicinal herbs have been increasingly used worldwide for diseases prevention and treatment. Rheum turkestanicum Janisch. is a perennial shrub of the Polygonaceae family. Genus Rheum includes more than 60 species growing around the world which are used in foods and traditional medicines. R. turkestanicum is believed to be able to improve different kinds of disorders including diabetes, hypertension, jaundice and cancer. In recent years, this medicinal plant has been a subject of many experimental studies to document its health-beneficial properties. These studies have revealed antidiabetic, anticancer, nephroprotective, cardioprotective, and hepatoprotective properties of R. turkestanicum. The presence of flavonoids (e.g. epicatechin and quercetin) and anthraquinones (e.g. chrysophanol, physcion, and emodin) in R. turkestanicum justifies its health-beneficial effects. Nevertheless, possible therapeutic applications and safety of this plant still need to be elucidated in further clinical studies.

Chinese herbal medicine for diabetic kidney disease: a systematic review and meta-analysis of randomised placebo-controlled trials

OBJECTIVES

To provide a broad evaluation of the efficacy and safety of oral Chinese herbal medicine (CHM) as an adjunctive treatment for diabetic kidney disease (DKD), including mortality, progression to end-stage kidney disease (ESKD), albuminuria, proteinuria and kidney function.

DESIGN

A systematic review and meta-analysis.

METHODS

Randomised controlled trials (RCTs) comparing oral CHM with placebo as an additional intervention to conventional treatments were retrieved from five English (Cochrane Central Register of Controlled Trials, MEDLINE, Embase, Allied and Complementary Medicine Database and Cumulative Index of Nursing and Allied Health Literature) and four Chinese databases (China BioMedical Literature, China National Knowledge Infrastructure, Chonqing VIP and Wanfang) from inception to May 2018. RCTs recruiting adult DKD patients induced by primary diabetes were considered eligible, regardless of the form and ingredients of oral CHM. Mean difference (MD) or standardised mean difference (SMD) was used to analyse continuous variables and RR for dichotomous data.

RESULTS

From 7255 reports retrieved, 20 eligible studies involving 2719 DKD patients were included. CHM was associated with greater reduction of albuminuria than placebo, regardless of whether renin-angiotensin system (RAS) inhibitors were concurrently administered (SMD -0.56, 95% CI [-1.04 to -0.08], I²=64%, p=0.002) or not (SMD -0.92, 95% CI [-1.35 to -0.51], I²=87%, p<0.0001). When CHM was used as an adjunct to RAS inhibitors, estimated glomerular filtration rate was higher in the CHM than placebo group (MD 6.28 mL/min; 95% CI [2.42 to 10.14], I²=0%, p=0.001). The effects of CHM on progression to ESKD and mortality were uncertain due to low event rates. The reported adverse events in CHM group included digestive disorders, elevated liver enzyme level, infection, anaemia, hypertension and subarachnoid haemorrhage, but the report rates were low and similar to control groups. The favourable results of CHM should be balanced with the limitations of the included studies such as high heterogeneity, short follow-up periods, small numbers of clinical events and older patients with less advanced disease.

CONCLUSIONS

Based on moderate to low quality evidence, CHM may have beneficial effects on renal function and albuminuria beyond that afforded by conventional treatment in adults with DKD. Further well-conducted, adequately powered trials with representative DKD populations are warranted to confirm the long-term effect of CHM, particularly on clinically relevant outcomes.

PROSPERO REGISTRATION NUMBER

CRD42015029293.

Improvement of vascular dysfunction by argirein through inhibiting endothelial cell apoptosis associated with ET-1/Nox4 signal pathway in diabetic rats

Endothelial cell apoptosis plays an important role in the pathophysiological mechanism of vascular complications in type 2 diabetes mellitus (T2DM). Argirein, a new synthetic compound was demonstrated to inactivate NADPH oxidase to alleviate cardiac dysfunction in T2DM. Here, we investigated whether argirein medication attenuated the vascular dysfunction in T2DM by inhibiting endothelial cell apoptosis which was associated with NADPH oxidase. The rat aortic endothelial cells (RAECs) were incubated with glucose (30 mM) for 48 hour in vitro. It was shown that high glucose significantly increased the protein expression of BAX (Bcl-2 Associated X protein) and Caspase-3 and decreased Bcl2 (B-Cell Leukemia/Lymphoma 2) protein level in RAECs, which was normalized by argirein medication. The annexin V-FITC bound cell percentage and DNA fragments in agarose electrophoresis were markedly suppressed by argirein to confirm the anti-apoptotic property of argirein in RAECs. Furthermore, we found that argirein blocked the endothelin (ET)-1/Nox4 signal-dependent superoxide (O₂^−.) generation, which regulated endothelial cell apoptosis in RAECs. In vivo, argirein intervention relieved the vasodilatory response to acetylcholine and restored the expressions of Nox4 and BAX in the aorta endothelium of high-fat diet (HFD)-fed rats following streptozocin (STZ) injection. For the first time, we demonstrated that argirein could inhibit vascular endothelial cell apoptosis, which was attributed to blocking ET-1/Nox4 signal-dependent O₂⁻ generation in RAECs. This current study revealed the therapeutic effects of argirein to prevent the vascular complication in T2DM through inhibiting endothelial cell apoptosis which was associated with the anti-oxidative property of argirein.

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.

Klotho preservation by Rhein promotes toll-like receptor 4 proteolysis and attenuates lipopolysaccharide-induced acute kidney injury

Renal anti-aging protein Klotho exhibits impressive properties of anti-inflammation and renal protection, however is suppressed early after renal injury, making Klotho restoration an attractive strategy of treating renal inflammatory disorders. Here, we reported that Klotho is enriched in macrophages and Klotho preservation by Rhein, an anthraquinone derived from medicinal plant rhubarb, attenuates lipopolysaccharide (LPS)-induced acute inflammation essentially via promoting toll-like receptor 4 (TLR4) degradation. LPS-induced pro-inflammatory NF-κB signaling and cytokine expressions coincided with Klotho repression and toll-like receptor 4 (TLR4) elevation in macrophages, renal epithelial cells, and acutely- inflamed kidney. Intriguingly, Rhein treatment effectively corrected the inverted alterations of Klotho and TLR4 and mitigated the TLR4 downstream inflammatory response in a Klotho restoration and TLR4 repression-dependent manner. Klotho inducibly associated with TLR4 after LPS stimulation and suppressed TLR4 protein abundance mainly via a proteolytic process sensitive to the inhibition of Klotho's putative β-glucuronidase activity. Consistently, Klotho knockdown by RNA interferences largely diminished the anti-inflammatory and renal protective effects of Rhein in a mouse model of acute kidney injury incurred by LPS. Thus, Klotho suppression of TLR4 via deglycosylation negatively controls TLR-associated inflammatory signaling and the endogenous Klotho preservation by Rhein or possibly other natural or synthetic compounds possesses promising potentials in the clinical treatment of renal inflammatory disorders.

KEY MESSAGES

• Klotho is highly expressed in macrophages and repressed by LPS in vitro and in vivo. • Klotho inhibits LPS-induced TLR4 accumulation and the downstream signaling. • Klotho decreases TLR4 via a deglycosylation-associated proteolytic process. • Rhein effectively prevents acute inflammation-incurred Klotho suppression. • Rhein reversal of Klotho attenuates LPS-induced acute inflammation and kidney injury.

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.

Rhein reverses Klotho repression via promoter demethylation and protects against kidney and bone injuries in mice with chronic kidney disease

Rhein is an anthraquinone compound isolated from the medicinal plant rhubarb and mainly used in the clinical treatment of diabetic nephropathy. Rhein exhibits various renoprotective functions, but the underlying mechanisms are not fully determined. However, its renoprotective properties recapitulate the role of Klotho, a renal-specific antiaging protein critical for maintaining kidney homeostasis. Here we explored the connections between rhein renoprotection and Klotho in a mouse model of adenine-induced chronic kidney disease. In addition to being an impressive Klotho upregulator, rhein remarkably reversed renal Klotho deficiency in adenine-treated mice. This effect was associated with significant improvement in disturbed serum biochemistry, profibrogenic protein expression, and kidney and bone damage. Further investigation of the molecular basis of Klotho loss revealed that these kidneys displayed marked inductions of DNA methyltransferase DNMT1/DNMT3a and Klotho promoter hypermethylation, whereas rhein treatment effectively corrected these alterations. The renal protective effects of rhein were largely abolished when Klotho was knocked-down by RNA interferences, suggesting that rhein reversal of Klotho deficiency is essential for its renoprotective actions. Thus, our study clarifies how rhein regulation of Klotho expression contributes to its renoprotection and brings new insights into Klotho-targeted strategy for the treatment of kidney diseases of various etiologies.

Genomic expression profiling and bioinformatics analysis on diabetic nephrology with ginsenoside Rg3

Diabetic nephropathy (DN), a common diabetes-related complication, is the leading cause of progressive chronic kidney disease (CKD) and end‑stage renal disease. Despite the rapid development in the treatment of DN, currently available therapies used in early DN cannot prevent progressive CKD. The exact pathogenic mechanisms and the molecular events underlying DN development remain unclear. Ginsenoside Rg3 is a herbal medicine with numerous pharmacological effects. To gain a greater understanding of the molecular mechanism and signaling pathway underlying the effect of ginsenoside Rg3 in DN therapy, an RNA sequencing approach was performed to screen differential gene expression in a rat model of DN treated with ginsenoside Rg3. A combined bioinformatics analysis was then conducted to obtain insights into the underlying molecular mechanisms of the disease development, in order to identify potential novel targets for the treatment of DN. Six Sprague‑Dawley male rats were randomly divided into 3 groups: Normal control group, DN group and ginsenoside‑Rg3 treatment group, with two rats in each group. RNA sequencing was adopted for transcriptome profiling of cells from the renal cortex of DN rat model. Differentially expressed genes were screened out. Cluster analysis, Gene Ontology (GO) and Kyoto Encyclopedia of Genes and Genomes (KEGG) enrichment analysis were used to analyze the differentially expressed genes. In total, 78 differentially expressed genes in the DN control group were identified when compared with the normal control group, of which 52 genes were upregulated and 26 genes were downregulated. Differential expression of 43 genes was observed in the ginsenoside‑Rg3 treatment group when compared with the DN control group, consisting of 10 upregulated genes and 33 downregulated genes. Notably, 21 that were downregulated in the DN control group compared with the control were then shown to be upregulated in the ginsenoside‑Rg3 treatment group compared with the DN control group. In addition, 7 upregulated genes in the DN control group compared with the control were then shown to be downregulated in the ginsenoside‑Rg3 treatment group compared with the DN control group. Cluster analysis based on differentially expressed genes indicated that the transcriptomes are quite different among the samples. Distinct GO terms associated with these groups of genes were shown to be enriched. KEGG pathway analysis demonstrated that differentially expressed genes were predominantly involved in the fatty acid metabolism pathway and peroxisome proliferator‑activated receptor (PPAR) signaling pathway. To the best of our knowledge, this study was the first to present whole genome expression profiling in DN with ginsenoside‑Rg3 treatment by RNA‑Seq. A set of differentially expressed genes and pathways were identified. These data provided an insight into understanding the molecular mechanisms underlying the effect of ginsenoside‑Rg3 treatment of DN.