Diacerhein downregulate proinflammatory cytokines expression and decrease the autoimmune diabetes frequency in nonobese diabetic (NOD) mice

Microalgae-Based Hydrogel for Inflammatory Bowel Disease and Its Associated Anxiety and Depression

Patients diagnosed with inflammatory bowel disease (IBD) exhibit a notable prevalence of psychiatric disorders, such as anxiety and depression. Nevertheless, the etiology of psychiatric disorders associated with IBD remains uncertain, and an efficacious treatment approach has yet to be established. Herein, an oral hydrogel strategy (SP@Rh-gel) is proposed for co-delivery of Spirulina platensis and rhein to treat IBD and IBD-associated anxiety and depression by modulating the microbiota-gut-brain axis. SP@Rh-gel improves the solubility, release characteristics and intestinal retention capacity of the drug, leading to a significant improvement in the oral therapeutic efficacy. Oral administration of SP@Rh-gel can reduce intestinal inflammation and rebalance the disrupted intestinal microbial community. Furthermore, SP@Rh-gel maintains intestinal barrier integrity and reduces the release of pro-inflammatory factors and their entry into the hippocampus through the blood-brain barrier, thereby inhibiting neuroinflammation and maintaining neuroplasticity. SP@Rh-gel significantly alleviates the colitis symptoms, as well as anxiety- and depression-like behaviors, in a chronic colitis mouse model. This study demonstrates the significant involvement of the microbiota-gut-brain axis in the development of IBD with psychiatric disorders and proposes a safe, simple, and highly efficient therapeutic approach for managing IBD and comorbid psychiatric disorders.

Rhein alleviates advanced glycation end products (AGEs)-induced inflammatory injury of diabetic cardiomyopathy in vitro and in vivo models

In diabetic patients, diabetic cardiomyopathy (DCM) is one of the most common causes of death. The inflammatory response is essential in the pathogenesis of DCM. Rhein, an anthraquinone compound, is extracted from the herb rhubarb, demonstrating various biological activities. However, it is unclear whether rhein has an anti-inflammatory effect in treating DCM. In our research, we investigated the anti-inflammatory properties as well as its possible mechanism. According to the findings in vitro, rhein could to exert an anti-inflammatory effect by reducing the production of NO, TNF-α, PGE2, iNOS, and COX-2 in RAW264.7 cells that had been stimulated with advanced glycosylation end products (AGEs). In addition, rhein alleviated H9C2 cells inflammation injury stimulated by AGEs/macrophage conditioned medium (CM). In vivo have depicted that continuous gavage of rhein could improve cardiac function and pathological changes. Moreover, it could inhibit the accumulation of AGEs and infiltration of inflammatory factors inside the heart of rats having DCM. Mechanism study showed rhein could suppress IKKβ and IκB phosphorylation via down-regulating TRAF6 expression to inhibit NF-κB pathway in AGEs/CM-induced H9C2 cells. Moreover, the anti-inflammation effect of rhein was realized through down-regulation phosphorylation of JNK MAPK. Furthermore, we found JNK MAPK could crosstalk with NF-κB pathway by regulating IκB phosphorylation without affecting IKKβ activity. And hence, the protective mechanism of rhein may involve the inhibiting of the TRAF6-NF/κB pathway, the JNK MAPK pathway, and the crosstalk between the two pathways. These results suggested that rhein may be a promising drug candidate in anti-inflammation and inflammation-related DCM therapy.

Attenuation of diethylnitrosamine-induced hepatocellular carcinoma in a rat model by combination therapy of diacerein and gold nanoparticles: a histopathological and immunohistochemical study

The purpose of this study was to investigate the effect of combined therapy of diacerein and gold nanoparticles (AuNP) on diethylnitrosamine (DEN) induced hepatocellular carcinoma (HCC) in a rat model. Normal healthy and DEN-induced (HCC) rats were divided into five groups. Group I healthy rats served as normal control, Group II untreated HCC rats, Group III HCC rats administered diacerein, Group IV HCC rats administered AuNP, and Group V HCC rats administered diacerein and AuNP. All treatments were given once daily for 4 weeks. Liver morphology and necroinflammation in all groups were evaluated using hematoxylin and eosin (H&E), Masson's trichrome for fibrosis, and immunohistochemistry assays for expression of TNF-α, IL-6, β-catenin, and caspase-3. Liver sections from Group II HCC rats showed loss of lobular architecture, thick fibrous tissue deposition, leukocyte infiltration, degenerated hepatocytes and HCC neoplastic nodules surrounded by extensive fibrosis. Group II had high expression of TNF-α, IL-6, and β-catenin, and low caspase-3 expression as compared to Group I. HCC rats treated with the combined therapy of diacerein and AuNP (Group V) showed markedly decreased HCC lesions, significant necroinflammation reduction (p ˂ 0.05) and 90% reduction in fibrosis as compared to Group II HCC + diacerein. This combined therapy also reduced (p ˂ 0.05) TNF-α, IL-6, β-catenin expression and increased caspase-3 expression. In conclusion, diacerein combined with AuNP synergistically attenuated the severity of HCC lesions by reducing necroinflammation and fibrosis, decreased TNF-α, IL-6, β-catenin expression, and increased caspase-3 expression for apoptosis.

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.

Overview of the Biological Activity of Anthraquinons and Flavanoids of the Plant Rumex Species

Rumex confertus belongs to the genus Rumex and is classified as an invasive parasitic plant in agriculture. Despite other Rumex species being widely used in herbal medicine due to their antimicrobial, antioxidant, antitumor, and anti-inflammatory effects, there are almost no information about the potential of Rumex confertus for the treatment of various diseases. In this review we analyzed scientific articles revealing properties of Rumex plant’s substances against cancer, diabetes, pathogenic bacterial invasions, viruses, inflammation, and oxidative stress for the past 20 years. Compounds dominating in each composition of solvents for extraction were discussed, and common thin layer chromatography(TLC) and high performance liquid chromatography(HPLC) methods for efficient separation of the plant’s extract are included. Physico-chemical properties such as solubility, hydrophobicity (Log P), pKa of flavonoids, anthraquinones, and other derivatives are very important for modeling of pharmacokinetic and pharmacodynamics. An overview of clinical studies for abounded selected substances of Rumex species is presented.

An Update of Anthraquinone Derivatives Emodin, Diacerein, and Catenarin in Diabetes

Diabetes is part of metabolic diseases and is characterized by high blood sugar levels over a prolonged period as result of an insulin-deficient production or an inappropriate response to insulin by our cells. This chronic disease was the direct cause of 1.6 million deaths in 2016 as reported by the World Health Organization. Emodin is a natural product and active ingredient of various Chinese herbs with the chemical formula 1,3,8-trihydroxy-6-methylanthraquinone. Diacerein is another naturally occurring anthraquinone (1,8-diacetoxy-3-carboxyanthraquinone) commonly used as commercial drug to treat osteoarthritis. These two anthraquinone derivatives have been shown to exert antidiabetic activities. Emodin seems to enhance the glucose tolerance and insulin sensibility via activation of PPARγ and modulation of metabolic-related genes. Diacerein seems to decrease inflammatory cytokines and increase insulin secretion enhancing insulin sensibility and therefore improving glucose control. Other naturally occurring anthraquinone derivatives, such as catenarin (1,4,6,8-tetrahydroxy-3-methylanthraquinone), have been shown to have antidiabetic activities although few studies have been performed. The synthesis of new emodin derivatives is increasing, but these new molecules have not been tested for diabetes treatment. In the current work, available literature on anthraquinone derivatives' effects in diabetes disease is reviewed. Moreover, we discuss the chemistry, food sources, bioavailability, and toxicity of the naturally occurring anthraquinone with antidiabetic effects.

Diacerein: A potential multi-target therapeutic drug for COVID-19

Severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2), which causes coronavirus disease 19 (COVID-19), was declared pandemic by the World Health Organization in March 2020. SARS-CoV-2 binds its host cell receptor, angiotensin-converting enzyme 2 (ACE2), through the viral spike (S) protein. The mortality related to severe acute respiratory distress syndrome (ARDS) and multi-organ failure in COVID-19 patients has been suggested to be connected with cytokine storm syndrome (CSS), an excessive immune response that severely damages healthy lung tissue. In addition, cardiac symptoms, including fulminant myocarditis, are frequent in patients in a severe state of illness. Diacerein (DAR) is an anthraquinone derivative drug whose active metabolite is rhein. Different studies have shown that this compound inhibits the IL-1, IL-2, IL-6, IL-8, IL-12, IL-18, TNF-α, NF-κB and NALP3 inflammasome pathways. The antiviral activity of rhein has also been documented. This metabolite prevents hepatitis B virus (HBV) replication and influenza A virus (IAV) adsorption and replication through mechanisms involving regulation of oxidative stress and alterations of the TLR4, Akt, MAPK, and NF-κB signalling pathways. Importantly, rhein inhibits the interaction between the SARS-CoV S protein and ACE2 in a dose-dependent manner, suggesting rhein as a potential therapeutic agent for the treatment of SARS-CoV infection. Based on these findings, we hypothesize that DAR is a multi-target drug useful for COVID-19 treatment. This anthraquinone may control hyperinflammatory conditions by multi-faceted cytokine inhibition and by reducing viral infection.

Diacerein treatment prevents colitis-associated cancer in mice

BACKGROUND

Inflammation is a well-established enabling factor for cancer development and provides a framework for the high prevalence of colon cancer in inflammatory bowel disease. In accordance, chronic inflammation has recently been implicated in the development of cancer stem cells (CSCs). However, the mechanism whereby anti-inflammatory drugs act in the prevention of colitis-associated cancer (CAC) is only partially understood.

AIM

To evaluate the role of diacerein (DAR), an anti-inflammatory drug that mainly acts through the inhibition of interleukin (IL)-1β expression in the development of CSCs and CAC.

METHODS

The effects of DAR on colon inflammation in mice with CAC were evaluated by inflammatory index, reverse real-time transcription polymerase chain reaction and western blot. Cytokine levels were measured by enzyme-linked immunosorbent assay. Cells assays evaluated the effects of DAR on CSCs. Immunohistochemistry and apoptosis assays were also used to evaluate the effects of DAR on tumorigenesis associated with inflammation.

RESULTS

DAR treatment reduced colon inflammation as well as the number and size of tumors in azoxymethane plus dextran sulphate sodium-treated animals. Accordingly, DAR treatment was associated with reduced intracellular signals of inflammation (inhibitor of nuclear factor kappa B kinase and c-Jun N-terminal kinase phosphorylation) in the colon. In addition, DAR treatment was associated with a decrease in colon CSC formation, suggesting that besides reducing colonic inflammation, DAR has a direct effect on the inhibition of colon carcinogenesis.

CONCLUSION

Together, these data indicate that DAR-mediated IL-1β suppression attenuates inflammation-induced colon cancer and CSC formation, highlighting DAR as a potential candidate for the chemoprevention of CAC.

Diacerein: Recent insight into pharmacological activities and molecular pathways

Diacerein is a symptomatic slow-acting drug in osteoarthritis (SYSADOA) and the active metabolite is rhein. It is a non-steroidal anti-inflammatory drug with unique pharmacological properties as anti-oxidant and anti-apoptosis. Diacerein has recently shown to have a potential role by mediating anti-inflammatory as well as anti-oxidant and anti-apoptosis in kidney injury, diabetes mullites, and a beneficial effect on pain relief. It may have a therapeutic role in cancer, ulcerative colitis, testicular injury and cervical hyperkeratosis. Furthermore, diacerein has a valuable addition in combination therapy as a synergetic agent. This review, the first of its kind, highlights the proposed roles of diacerein in osteoarthritis and discusses recent results supporting its emerging roles with a particular focus on how these new insights may facilitate the rational development of diacerein for targeted therapies in the future.

Efficacy of diacerein in reducing liver steatosis and fibrosis in patients with type 2 diabetes and non-alcoholic fatty liver disease: A randomized, placebo-controlled trial

The aim was to assess, in a randomized, double-blinded, placebo-controlled trial, the efficacy of diacerein, an anti-inflammatory drug, in improving liver fibrosis and steatosis in patients with type 2 diabetes and non-alcoholic fatty liver disease (NAFLD). Sixty-nine diabetic patients with NAFLD were randomized to 24-month treatment with placebo (35 patients) or diacerein 100 mg/day (34 patients). Liver stiffness and steatosis were assessed by transient elastography (Fibroscan®) at baseline, and 12 and 24 months of follow-up. The primary outcome was the difference in mean liver stiffness and steatosis changes during treatment. Adjusted differences in mean changes on intention-to-treat analyses were estimated by generalized repeated-measures mixed-effects regressions. Diacerein significantly reduced liver stiffness in contrast to placebo by 1.6 kPa (95% CI: -2.6 to -0.5 kPa; p = 0.003), whereas no significant difference in mean changes in liver steatosis was observed. The reduction in liver stiffness was already evident at the 12-month examination, and accentuated at the 24-month examination. Eight patients reduced liver fibrosis stage during treatment, seven of whom were in the diacerein group (p = 0.020). In conclusion, a 2-year treatment with diacerein significantly reduced liver fibrosis in diabetic patients with NAFLD.

Diacerein alleviates kidney injury through attenuating inflammation and oxidative stress in obese insulin-resistant rats

A link between inflammation with obesity and metabolic syndrome has been found in patients with chronic kidney disease (CKD). Diacerein is an anthraquinone used to treat osteoarthritis that exerts anti-inflammatory action by inhibiting the synthesis and activity of proinflammatory cytokines. This study aimed to investigate the protective effect of diacerein on renal function and renal organic anion transporter 3 (Oat3) function in obese insulin-resistant condition. Obese insulin-resistant rats were induced by feeding a high-fat diet in male Wistar rats for 16 weeks. Diacerein or metformin (positive control) (30mg/kg/day) was administered orally for 4 weeks after insulin resistance had been confirmed. Obese insulin-resistant rats showed an impaired renal function as indicated by the increased serum creatinine and microalbuminuria along with the decreased renal Oat3 function and expression. Importantly, diacerein treatment not only improved insulin resistance but also restored renal function. The decreased renal malondialdehyde level, expressions of PKCα, angiotensin 1 receptor (AT1R), Nrf2, and HO-1, and increased expression of SOD2 were observed in diacerein treatment group, indicating the attenuation of renal oxidative stress condition. Moreover, renal inflammation and renal damage were also alleviated in diacerein-treated rats. Our results demonstrated for the first time that diacerein was effective to improve renal function and renal Oat3 function in obese insulin-resistance condition mediated by suppressing renal oxidative stress and inflammation. These findings suggest that anti-inflammatory agents can be used therapeutically to improve metabolic disorder and prevent organ dysfunctions in pre-diabetic condition.

Effect of Diacerein on Metabolic Control and Inflammatory Markers in Patients with Type 2 Diabetes Using Antidiabetic Agents: A Randomized Controlled Trial

INTRODUCTION

Studies have shown that T2DM is an inflammatory disease. Thus, the present study was aimed at evaluating whether diacerein could improve the metabolic and inflammatory profile among patients with T2DM under long-term treatment with glucose-lowering agents.

METHODS

This is a double-blind, parallel, placebo-controlled trial with 72 participants randomly assigned to diacerein 50 mg or placebo for 12 weeks. The primary endpoint was the between-group difference in change in HbA1c. Secondary endpoints included the proportion of patients achieving metabolic control [HbA1c ≤ 7.0% (53 mmol/mol)] and change in inflammatory mediators.

RESULTS

Participants in the diacerein group had greater reductions in mean HbA1c level in comparison to placebo (-0.98; 95% CI: -2.02 to 0.05, P = 0.06), independently of confounding factors. The difference in HbA1c level was -1.3 (95% CI: -2.3 to -0.4) in favor of diacerein (P = 0.007) in those with <14 years of diabetes duration versus 0.05 (-0.7 to 0.8; P = 0.9) in those with longer duration. The diacerein group had a 50% increase in the number of participants at the lowest TNF-α level (≤1.46 pg/mL).

CONCLUSIONS

In patients with long-established T2DM under long-term treatment with glucose-lowering agents, diacerein improves metabolic control as measured by HbA1c level and has a favorable impact on inflammatory profile.

CLINICAL TRIAL REGISTRY

This trial is registered with Brazilian Clinical Trials Registry (ReBEC) number RBR-29j956.

Effect of diacerein on renal function and inflammatory cytokines in participants with type 2 diabetes mellitus and chronic kidney disease: A randomized controlled trial

Diacerein seems to improve metabolic control and reduce inflammatory marker levels in individuals with type 2 diabetes mellitus (Type 2 DM), but for participants with chronic kidney disease (CKD) its effect is unknown. This study aimed to evaluate the effect of diacerein vs. placebo on urinary albumin/creatinine ratio (ACR), glomerular filtration rate (GFR), and inflammatory cytokines in type 2 DM participants with CKD. Blood pressure (BP) and metabolic control were secondary outcomes. This randomized, placebo-controlled, parallel trial of adjuvant treatment of type 2 DM with diacerein enrolled seventy-two participants with CKD, aged 30–80 years, with glycated hemoglobin levels from 53–97 mmol/mol (7.0–11.0%), receiving angiotensin-converting enzyme inhibitors or angiotensin receptor blockers and antidiabetic agents. Participants randomized to diacerein or placebo were followed-up up to 90 days. Both groups had a marked reduction in ACR, but there was no effect on glomerular filtration rate. While the diacerein group had reduced TNF-α levels at the 75th percentile with a borderline significance (P = 0.05), there were no changes in the IL levels at the 75^th percentile.

Diacerein prevented the increase in blood glucose to the level observed in the placebo group (P = 0.04), improving metabolic control by 74%, reducing 24-hour diastolic BP, nighttime systolic and diastolic BP compared to the placebo group. In conclusion, among patients with type 2 DM and CKD, diacerein does not have an effect on ACR or GFR, but slows metabolic control deterioration and is associated with lower nighttime systolic and diastolic blood pressure.

Trial registration: Brazilian Clinical Trials Registry (Registro Brasileiro de Ensaios Clinicos; ReBeC) U1111-1156-0255

Efficacy and Safety of Diacerein in Patients With Inadequately Controlled Type 2 Diabetes: A Randomized Controlled Trial

OBJECTIVE

To assess, in a randomized, double-blind, and placebo-controlled trial, the efficacy and safety of diacerein, an immune modulator anti-inflammatory drug, in improving glycemic control of patients with type 2 diabetes.

RESEARCH DESIGN AND METHODS

Eighty-four patients with HbA_1c between 7.5 and 9.5% (58-80 mmol/mol) were randomized to 48-week treatment with placebo (n = 41) or diacerein 100 mg/day (n = 43). The primary outcome was the difference in mean HbA_1c changes during treatment. Secondary outcomes were other efficacy and safety measurements. A general linear regression with repeated measures, adjusted for age, sex, diabetes duration, and each baseline value, was used to estimate differences in mean changes. Both intention-to-treat (ITT) analysis and per-protocol analysis (excluding 10 patients who interrupted treatment) were performed.

RESULTS

Diacerein reduced HbA_1c compared with placebo by 0.35% (3.8 mmol/mol; P = 0.038) in the ITT analysis and by 0.41% (4.5 mmol/mol; P = 0.023) in the per-protocol analysis. The peak of effect occurred at the 24th week of treatment (-0.61% [6.7 mmol/mol; P = 0.014] and -0.78% [8.5 mmol/mol; P = 0.005], respectively), but it attenuated toward nonsignificant differences at the 48th week. No significant effect of diacerein was observed in other efficacy and safety measures. Diarrhea occurred in 65% of patients receiving diacerein and caused treatment interruption in 16%. Seven patients in the diacerein group reduced insulin dosage, whereas 10 in the placebo group increased it; however, mild hypoglycemic events were equally observed.

CONCLUSIONS

Diacerein reduced mean HbA_1c levels, with peak of effect at the 24th week of treatment. The drug was well tolerated and may be indicated as adjunct treatment in patients with type 2 diabetes, particularly in those with osteoarthritis.

Dystrophic phenotype improvement in the diaphragm muscle of mdx mice by diacerhein

Chronic inflammation and oxidative stress are striking features of Duchenne muscular dystrophy disease. Diacerhein is an anthraquinone, which exhibits anti-inflammatory and antioxidant properties. Based on their actions, the present study evaluated the effects of diacerhein against myonecrosis, oxidative stress and inflammatory response in the diaphragm muscle of mdx mice and compared these results to current treatment widely used in DMD patients, with a main focus on the impact of prednisone. The results demonstrated that diacerhein treatment prevented muscle damage indicated by a decrease in the IgG uptake by muscle fibers, lower CK levels in serum, reduction of fibers with central nuclei with a concomitant increase in fibers with peripheral nuclei. It also had an effect on the inflammatory process, decreasing the inflammatory area, macrophage staining and TNF-α and IL-1β content. Regarding oxidative stress, diacerhein treatment was effective in reducing the ROS and lipid peroxidation in the diaphragm muscle from mdx mice. Compared to prednisone treatment, our findings demonstrated that diacerhein treatment improved the dystrophic phenotype in the diaphragm muscle of mdx mice similar to that of glucocorticoid therapy. In this respect, this work suggests that diacerhein has a potential use as an alternative drug in dystrophinopathy treatment and recommends that its anti-inflammatory and antioxidants properties in the dystrophic muscle should be better understood.

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

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

Effect of diacerein as an add-on to metformin in patients with type 2 diabetes mellitus and inadequate glycemic control

OBJECTIVE

To evaluate the effect of diacerein as an add-on to metformin in patients with type 2 diabetes mellitus (T2DM) and inadequate glycemic control.

MATERIALS AND METHODS

A randomized, double-blind, placebo-controlled clinical trial was carried out on 12 patients with T2DM and inadequate glycemic control [glycated hemoglobin A1c (A1C) ≥ 7%] with metformin as monotherapy (≥ 1500 mg per day) for at least the previous 90 days. Fasting and postprandial glucose were measured before and after the pharmacological intervention. A1C, lipid profile, creatinine and uric acid were also evaluated. After randomization, all patients continued with their dose of metformin. Six subjects received placebo and the other six volunteers took diacerein. Data were tested using the Wilcoxon signed-rank, Mann-Whitney U and chi-square tests. The Institutional Ethics Committee approved the study protocol.

RESULTS

After 90 days of diacerein as an add-on to metformin, there was a significant decrease in fasting glucose (196 ± 79 vs. 149 ± 70 mg/dL, p < 0.05), postprandial glucose (262 ± 99 vs. 187 ± 70 mg/dlL, p < 0.05) and A1C (8.4 ± 2.0 vs. 6.7 ± 1.7 %, p < 0.05).

CONCLUSIONS

Diacerein as an add-on to metformin in patients with T2DM improved their glycemic control.

Development, characterization and in vitro evaluation of biodegradable rhein-loaded microparticles for treatment of osteoarthritis

Rhein is an active metabolite of the drug diacerein, whose anti-inflammatory properties have been demonstrated in both in vitro and in vivo models. However, the low oral bioavailability of rhein has limited its utility as a potential treatment of osteoarthritis (OA), a chronic inflammatory disease. In order to overcome this limitation, the aim of this work was the development of a drug delivery system intended for intra-articular administration of rhein, based on polymeric biodegradable PLGA microparticles (MPs) loaded with the drug. The MPs, prepared by the emulsion-solvent evaporation technique were characterized in terms of several parameters including morphology, encapsulation efficiency, molecular interactions between components of the formulation and in vitro release profiling. Furthermore, cell-based in vitro studies were performed to evaluate the cytotoxicity of the formulations and their effect on the release of inflammatory markers including pro-inflammatory cytokines and reactive oxygen species (ROS). Scanning electron microscopy demonstrated that the prepared MPs exhibited an almost spherical shape with smooth surface. The size distribution of the prepared MPs ranged between 1.9 and 7.9μm, with mean diameter of 4.23±0.87μm. The optimal encapsulation efficiency of rhein was 63.8±3.0%. The results of powder X-ray diffraction and differential scanning calorimetry studies demonstrated that the active ingredient is partially the crystalline state, dispersed in the polymer matrix. This outcome is somewhat reflected in the release kinetics of rhein from the MPs. The cytotoxicity evaluation, carried out in macrophages derived from THP-1 cells, showed that both rhein-loaded MPs and unloaded MPs did not significantly affect the cell viability at MP concentrations up to 13.8μM. In lipopolysaccharide-activated macrophages, the rhein-loaded MPs significantly decreased the production of interleukin-1β (IL-1β) and (ROS), when compared to the unloaded MPs. In conclusion, the results of this preliminary study suggest that an MP-based formulation of rhein could be tested in animal models of inflammation, aiming for an injectable commercial product capable of providing a therapeutic solution to patients suffering from chronic joint diseases.

Chronic rhein treatment improves recognition memory in high-fat diet-induced obese male mice

High-fat (HF) diet modulates gut microbiota and increases plasma concentration of lipopolysaccharide (LPS) which is associated with obesity and its related low-grade inflammation and cognitive decline. Rhein is the main ingredient of the rhubarb plant which has been used as an anti-inflammatory agent for several millennia. However, the potential effects of rhein against HF diet-induced obesity and its associated alteration of gut microbiota, inflammation and cognitive decline have not been studied. In this study, C57BL/6J male mice were fed an HF diet for 8 weeks to induce obesity, and then treated with oral rhein (120 mg/kg body weight/day in HF diet) for a further 6 weeks. Chronic rhein treatment prevented the HF diet-induced recognition memory impairment assessed by the novel object recognition test, neuroinflammation and brain-derived neurotrophic factor (BDNF) deficits in the perirhinal cortex. Furthermore, rhein inhibited the HF diet-induced increased plasma LPS level and the proinflammatory macrophage accumulation in the colon and alteration of microbiota, including decreasing Bacteroides-Prevotella spp. and Desulfovibrios spp. DNA and increasing Bifidobacterium spp. and Lactobacillus spp. DNA. Moreover, rhein also reduced body weight and improved glucose tolerance in HF diet-induced obese mice. In conclusion, rhein improved recognition memory and prevented obesity in mice on a chronic HF diet. These beneficial effects occur via the modulation of microbiota, hypoendotoxinemia, inhibition of macrophage accumulation, anti-neuroinflammation and the improvement of BDNF expression. Therefore, supplementation with rhein-enriched food or herbal medicine could be beneficial as a preventive strategy for chronic HF diet-induced cognitive decline, microbiota alteration and neuroinflammation.

Effects of rhein lysinate on D-galactose-induced aging mice

The aim of the present study was to investigate the anti-aging effects of rhein lysinate (RHL), and to explore its mechanism of action in a D-galactose-induced aging mouse model. Aging was induced by D-galactose (100 mg/kg/day) that was subcutaneously injected to animals for 8 weeks. RHL was simultaneously administered once a day by intragastric gavage. The appetite, mental condition, body weight and organ index of the mice were monitored. Superoxide dismutase (SOD) and glutathione peroxidase (GSH-Px) activities were determined, and the levels of malondialdehyde (MDA) in the liver, kidney and serum were measured by appropriate assay kits. Western blot analysis was used to detect proteins associated with age. The results indicated that RHL may improve the appetite, mental state and organ conditions of the model mice, improve the activities of SOD and GSH-Px, reduce MDA levels and modulate the expression of age-associated proteins (Sirtuin 1, p21 and p16) in D-galactose-induced mice. Therefore, RHL may be effective at suppressing the aging process through a combination of enhancing antioxidant activity, scavenging free radicals and modulating aging-associated gene expression.

Rhein antagonizes P2X7 receptor in rat peritoneal macrophages

P2X7 receptor plays important roles in inflammation and immunity, and thereby it serves as a potential therapeutic target for inflammatory diseases. Rhein, an anthraquinone derivative, exhibits significant anti-inflammatory and immunosuppressive activities in therapy. However, the underlying mechanisms are largely unclear. Here, we aimed to investigate the effects of rhein on P2X7 receptor-mediated responses in vitro. In HEK293 cells expressing rat P2X7 receptor, we first found that rhein concentration-dependently blocked ATP-induced cytosolic calcium concentration ([Ca(2+)]c) elevation and pore formation of the plasma membrane, two hallmarks of the P2X7 receptor activation. These two inhibitory effects of rhein were also observed in rat peritoneal macrophages. Furthermore, rhein counteracted macrophage phagocytosis attenuation and suppressed reactive oxygen species (ROS) production triggered by ATP/BzATP. Meanwhile, rhein reduced ATP/BzATP-induced IL-1β release in lipopolysaccharide-activated macrophages. Prolonged application of ATP caused macrophage apoptosis, while the presence of rhein suppressed this cell cytotoxicity. Such ATP/BzATP-induced cellular reactions were also inhibited by a well-known rat P2X7 receptor antagonist, brilliant blue G, in a similar way to rhein. Together, our results demonstrate that rhein inhibit ATP/BzATP-induced [Ca(2+)]c increase, pore formation, ROS production, phagocytosis attenuation, IL-1β release and cell apoptosis by antagonizing the P2X7 receptor in rat peritoneal macrophages.

Experimental osteoarthritis model by means of medial meniscectomy in rats and effects of diacerein administration and hyaluronic acid injection

CONTEXT AND OBJECTIVE

The development of a slow and progressive mechanical model for osteoarthritis is important for correlation with clinical practice, and for evaluating the effects of disease-modifying medications. A mechanical osteoarthritis model was developed to evaluate the effects of intra-articular hyaluronic acid (HA) injection and oral diacerein administration.

DESIGN AND SETTING

Experimental study at the Department of Orthopedics and Traumatology, Universidade de São Paulo.

METHOD

Total medial meniscectomy was performed on seven groups of ten Wistar rats each, comprising four control groups (C) and three study groups (S). C.I: operated, non-medicated; C.II: operated, injections of HA vehicle; C.III: non-operated, non-medicated; C.IV: operated, non-medicated, sacrificed three months post-meniscectomy; S.I: operated, receiving intra-articular HA injections; S.II: operated, oral diacerein from the third to the seventh postoperative month; S.III: operated, received both medications. All the animals (except C.IV) were sacrificed seven months post-meniscectomy. All femurs and tibias were assessed histologically.

RESULTS

The most severe degenerative histological changes were in the tibias of the operated knees. On the contralateral side, all groups had mild changes on the tibial surface. The femoral surface had slight changes. C.I showed severe changes. S.II results matched those of C.IV. HA protected the tibial surface. S.II and S.III had similar results.

CONCLUSIONS

1) The experimental model produced mild arthritis after three months and severe arthritis after seven months; 2) diacerein reduced the degenerative changes in both knees; 3) HA protected the joint cartilage; 4) Combining the two drugs did not improve the results.

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

AIM

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

MATERIALS AND METHODS

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

RESULTS

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

CONCLUSION

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

Antioxidant and anti-diabetic potential of Passiflora alata Curtis aqueous leaves extract in type 1 diabetes mellitus (NOD-mice)

Leaves of Passiflora alata Curtis were characterized for their antioxidant capacity. Antioxidant analyses of DPPH, FRAP, ABTS, ORAC and phenolic compounds were made in three different extracts: aqueous, methanol/acetone and ethanol. Aqueous extract was found to be the best solvent for recovery of phenolic compounds and antioxidant activity, when compared with methanol/acetone and ethanol. To study the anti-inflammatory properties of this extract in experimental type 1 diabetes, NOD mice were divided into two groups: the P. alata group, treated with aqueous extract of P. alata Curtis, and a non-treated control group, followed by diabetes expression analysis. The consumption of aqueous extract and water ad libitum lasted 28 weeks. The treated-group presented a decrease in diabetes incidence, a low quantity of infiltrative cells in pancreatic islets and increased glutathione in the kidney and liver (p<0.05), when compared with the diabetic and non-diabetic control-groups. In conclusion, our results suggest that the consumption of aqueous extract of P. alata may be considered a good source of natural antioxidants and compounds found in its composition can act as anti-inflammatory agents, helping in the control of diabetes.

Hypoxia alters pharmacokinetics of argirein because of mitochondrial dysfunction that is alleviated by apocynin

OBJECTIVES

Pharmacokinetics (PK) of argirein might be changed in response to mitochondrial (MITO) dysfunction and activated nicotinamide adenine dinucleotide phosphate oxidase (NOX) on hypoxia. We hypothesized that hypoxic changes in MITO and NOX could alter PK and tissue distribution of argirein. We tested if these changes in PK of argirein by hypoxia could be relieved by apocynin (APO), a blocker of NOX, through normalizing MITO and NOX.

METHODS

Male Sprague-Dawley rats were exposed to hypoxia (O2 10% ± 5% 8 h per day) for 7 days and treated with APO (80 mg/kg, i.g.) in the last 4 days. The PK and tissue distribution of argirein were monitored by measuring its main metabolite rhein using HPLC analysis. Manganese superoxide dismutase (MnSOD) and NOX were assayed.

KEY FINDINGS

The PK parameters and concentrations of rhein in the kidney, liver, heart and testes were significantly altered under hypoxia, accompanied with a reduced MnSOD and upregulated NOX compared with the normal. Altered argirein PK and distribution in these organs were relieved following APO administration.

CONCLUSION

Abnormal PK and distribution of argirein by assaying its metabolite rhein are significant, consequent to hypoxic injury that is significantly ameliorated by APO through normalizing MITO and NOX.

Rhein lysinate decreases the generation of β-amyloid in the brain tissues of Alzheimer's disease model mice by inhibiting inflammatory response and oxidative stress

The protective effect of rhein lysinate (RHL) on Alzheimer's disease (AD) was explored in senescence-accelerated mouse prone-8 (SAMP8) mice. SAMP8 mice without treatment were used as the AD-positive control, and senescence-accelerated-resistant mice were used as the AD-negative control. In this study, 4-month-old male SAMP8 mice were orally administered 25 and 50 mg/kg RHL in drinking water for 6 months. The results of brain tissue enzyme-linked immunosorbent assay (ELISA), immunohistochemistry, and Western blot were demonstrated that compared with SAMP8 group, β-amyloid1-40 and β-amyloid1-42 were reduced; the levels of tumor necrosis factor-α and interleukin 6 of brain tissues were also significantly decreased; however, the level of sirtuin 1 (SIRT1) was increased in the RHL-treated group. Compared with SAMP8 group, the ROS levels and malondialdehyde levels were decreased; however, superoxide dismutase and glutathione peroxidase levels were increased in the brain tissues of SAMP8 25 and 50 mg/kg RHL-treated groups. In conclusion, the reduction of Aβ induced by RHL was related to the increase of SIRT1 and the inhibition of the inflammatory response and oxidative stress in SAMP8 mice. It might be a promising biological therapeutic drug for AD.

Rhein protects against obesity and related metabolic disorders through liver X receptor-mediated uncoupling protein 1 upregulation in brown adipose tissue

Liver X receptors (LXRs) play important roles in regulating cholesterol homeostasis, and lipid and energy metabolism. Therefore, LXR ligands could be used for the management of metabolic disorders. We evaluated rhein, a natural compound from Rheum palmatum L., as an antagonist for LXRs and investigated its anti-obesity mechanism in high-fat diet-fed mice. Surface plasmon resonance assays were performed to examine the direct binding of rhein to LXRs. LXR target gene expression was assessed in 3T3-L1 adipocytes and HepG2 hepatic cells in vitro. C57BL/6J mice fed a high-fat diet were orally administered with rhein for 4 weeks, and then the expression levels of LXR-related genes were analyzed. Rhein bound directly to LXRs. The expression levels of LXR target genes were suppressed by rhein in 3T3-L1 and HepG2 cells. In white adipose tissue, muscle and liver, rhein reprogrammed the expression of LXR target genes related to adipogenesis and cholesterol metabolism. Rhein activated uncoupling protein 1 (UCP1) expression in brown adipose tissue (BAT) in wild-type mice, but did not affect UCP1 expression in LXR knockout mice. In HIB-1B brown adipocytes, rhein activated the UCP1 gene by antagonizing the repressive effect of LXR on UCP1 expression. This study suggests that rhein may protect against obesity and related metabolic disorders through LXR antagonism and regulation of UCP1 expression in BAT.

Genetic variation of IL-12B (+1188 region) is associated with its decreased circulating levels and susceptibility to Type 2 diabetes

BACKGROUND

Type 2 diabetes mellitus is one of the most common types of endocrine disease and the immune system plays a predominant role in its pathogenesis.

AIMS

The present study aimed to examine known gene polymorphisms within IL-12B (+1188) region and its circulating serum levels in Type 2 diabetic patients from the southeastern region of Iran and compare them with unrelated controls.

MATERIALS & METHODS

In this clinical study, peripheral blood was collected from 114 Type 2 diabetic patients and 100 healthy controls. Serum levels of IL-12B were measured by ELISA. Genomic DNA was extracted from peripheral blood samples and polymorphisms at the +1188 position of the IL-12B gene were assessed using PCR restriction fragment-length polymorphism.

RESULTS

Our findings demonstrated that the AA genotype and the A allele of IL-12B were increased significantly in Type 2 diabetic patients when compared with controls. Our results also showed that the circulating levels of IL-12B were significantly decreased in Type 2 diabetic patients when compared with controls.

CONCLUSION

According to the findings of the current study, we concluded that IL-12B and its +1188 polymorphism may play a prominent role in the pathogenesis of Type 2 diabetes. Further replicative investigations using a larger sample size are essential to identify additional IL-12B genetic variants associated with a risk of Type 2 diabetes.

Catenarin Prevents Type 1 Diabetes in Nonobese Diabetic Mice via Inhibition of Leukocyte Migration Involving the MEK6/p38 and MEK7/JNK Pathways

Inflammation contributes to leukocyte migration, termed insulitis, and β-cell loss in type 1 diabetes (T1D). Naturally occurring anthraquinones are claimed as anti-inflammatory compounds; however, their actions are not clear. This study aimed to investigate the effect and mechanism of catenarin on the inflammatory disease, T1D. Catenarin and/or its anthraquinone analogs dose-dependently suppressed C-X-C chemokine receptor type 4 (CXCR4)- and C-C chemokine receptor type 5 (CCR5)-implicated chemotaxis in leukocytes. Catenarin, the most potent anthraquinone tested in the study, prevented T1D in nonobese diabetic mice. Mechanistic study showed that catenarin did not act on the expression of CCR5 and CXCR4. On the contrary, catenarin inhibited CCR5- and CXCR4-mediated chemotaxis via the reduction of the phosphorylation of mitogen-activated protein kinases (p38 and JNK) and their upstream kinases (MKK6 and MKK7), and calcium mobilization. Overall, the data demonstrate the preventive effect and molecular mechanism of action of catenarin on T1D, suggesting its novel use as a prophylactic agent in T1D.

Diacerhein improves glucose tolerance and insulin sensitivity in mice on a high-fat diet

Obesity and type 2 diabetes are characterized by insulin resistance, and the common basis of these events is a chronic and systemic inflammatory process marked by the activation of the c-Jun N-terminal kinase (JNK) and inhibitor-κB kinase (IKKβ)/nuclear factor-κB (NFκB) pathways, up-regulated cytokine synthesis, and endoplasmic reticulum dysfunction. The aim of this study was to evaluate the effects of diacerhein administration, an antiinflammatory drug that reduces the levels of inflammatory cytokines, on insulin sensitivity and signaling in diet-induced obese (DIO) mice. Swiss mice were fed with conventional chow (control group) or a high-fat diet (DIO group). Later, DIO mice were randomly subdivided into a new subgroup (DAR) that received 20 mg/kg diacerhein for 10 d. Western blotting was used to quantify the expression and phosphorylation of insulin receptor, insulin receptor substrate 1, and Akt and of inflammatory mediators that modulate insulin signaling in a negative manner (IKKβ, JNK, and inducible nitric oxide synthase). We show here, for the first time, that the administration of diacerhein in DIO mice improved endoplasmic reticulum stress, reduced JNK and IKKβ phosphorylation, and resulted in a marked improvement in fasting glucose, a decrease in macrophage infiltration in adipose tissue, and a reduced expression and activity of proinflammatory mediators accompanied by an improvement in the insulin signaling mainly in the liver and adipose tissue. Taken together, these results indicate that diacerhein treatment improves insulin sensitivity in obesity, mediated by the reversal of subclinical inflammation, and that this drug may be an alternative therapy for insulin resistance.

Effect of diacerein on insulin secretion and metabolic control in drug-naive patients with type 2 diabetes: a randomized clinical trial

OBJECTIVE

To assess the effect of diacerein on insulin secretion and metabolic control in drug-naïve patients with type 2 diabetes.

RESEARCH DESIGN AND METHODS

A randomized, double-blind, placebo-controlled clinical trial was carried out in 40 drug-naïve adult patients with type 2 diabetes. A metabolic profile including interleukin (IL)-1β, tumor necrosis factor-α, IL-6, and fasting insulin levels was carried out before the intervention and 2 months afterward. A hyperglycemic-hyperinsulinemic clamp technique was performed to assess the phases of insulin secretion and insulin sensitivity. After randomization, 20 patients received diacerein (50 mg once daily) for the first 15 days and twice daily for 45 additional days. The remaining patients received placebo. Intra- and intergroup differences were calculated by Wilcoxon signed rank and Mann-Whitney U tests.

RESULTS

There were significant increases in first (102±63 vs. 130±75 pmol/L; P<0.01), late (219±111 vs. 280±135 pmol/L; P<0.01), and total insulin (178±91 vs. 216±99 pmol/L; P<0.01) secretions without changes in insulin sensitivity after diacerein administration. There were significant decreases in fasting glucose (7.9±1.4 vs. 6.8±1.0 mmol/L; P<0.01) and in A1C levels (8.3±1.0 vs. 7.0±0.8%; P<0.001) after diacerein administration. There were no significant changes after placebo administration in the above-mentioned evaluations.

CONCLUSIONS

Insulin secretion increased and metabolic control improved after diacerein administration in drug-naïve patients with type 2 diabetes.

Rhein ameliorates fatty liver disease through negative energy balance, hepatic lipogenic regulation, and immunomodulation in diet-induced obese mice

Nonalcoholic fatty liver disease (NAFLD) is associated with obesity, insulin resistance, and inflammatory disorders. In this study, we tested the effect of rhein, a lipophilic anthraquinone derived from a traditional Chinese herbal medicine Rheum palmatum L., on NAFLD-associated hepatic steatosis, insulin resistance, and the T helper (Th)1/Th2 cytokine imbalance in high-fat diet-induced obese (DIO) mice. We found that oral administration of rhein for 40 days significantly increased energy expenditure, reduced body weight, particularly body fat content, improved insulin resistance, and lowered circulating cholesterol levels in DIO mice without affecting food intake. Rhein treatment also reduced liver triglyceride levels, reversed hepatic steatosis, and normalized alanine aminotransferase (ALT) levels in these mice. Gene analysis and Western blot showed that rhein markedly suppressed the expression of the lipogenic enzyme sterol regulatory element-binding protein-1c (SREBP-1c) and its target genes in the liver. Luciferase reporter assay revealed that rhein suppressed the transcriptional activity of SREBP-1c through its upstream regulator, liver X receptor (LXR). This suggests that rhein exerts its effects by targeting LXR, which is also supported by its inability to reduce body weight in LXR knockout mice. Moreover, multiplex ELISA displayed a downregulated Th1 response after rhein treatment. Rhein shifted the Th1/Th2 responses by inhibiting T-box expressed in T-cells (T-bet) expression and enhancing GATA-binding protein-3 (GATA-3) expression through increased signal transducer and activator of transcription 6 (STAT6) phosphorylation. These data indicate that rhein ameliorated NAFLD and associated disorders through LXR-mediated negative energy balance, metabolic regulatory pathways, and immunomodulatory activities involved in hepatic steatosis. The combined effects of rhein to target hepatic metabolic and immune pathways may be beneficial for complex metabolic diseases such as NAFLD.

Isoproterenol-induced FKBP12.6/12 downregulation is modulated by ETA and ETB receptors and reversed by argirhein, a derivative of rhein

AIM

To investigate which endothelin receptors mediated isoproterenol (ISO)-induced downregulation of FKBP12.6/12 in cardiomyocytes and study whether argirhein, a novel compound containing rhein and L-arginine that has anti-inflammatory activity, could reverse the downregulation of FKBP12.6/12 induced by ISO.

METHODS

Neonatal rat cardiomyocytes were incubated with ISO to downregulate FKBP12.6/12. Then the cells were treated with a selective ET(A) blocker (PD156707) and a ET(B) blocker (IRL1038), a dual ET(A)/ET(B) antagonist (CPU0213), and argirhein, respectively. FKBP12.6/12 expression was assayed by RT-PCR, Western blot, and immunocytochemistry.

RESULTS

The expression of FKBP12.6 mRNA was reduced by 37.7% (P<0.01) and 28.9% (P<0.05) relative to the control by ISO 1 and 0.1 μmol/L, respectively, but no response to ISO 0.01 μmol/L was observed in vitro. FKBP12.6/12 protein expression was reduced by 47.2% (P<0.01) and 37.8% (P<0.05) by ISO 1 and 0.1 μmol/L, respectively. This decrease was reversed significantly by PD156707, or IRL1038, and CPU0213. CPU0213 was more potent than either PD156707 or IRL-1038. Argirhein 10 μmol/L blunted the downregulation of FKBP12.6/12 by ISO, as demonstrated by the rising mRNA and protein levels and by the fluorescent density of the ISO-incubated cardiomyocytes.

CONCLUSION

In cardiomyocytes, the ISO induced downregulation of FKBP12.6/12 is modulated by both ET(A) and ET(B). A new compound, argirein, reversed the down-regulation of FKBP12.6/12 expression in myocardial cells stimulated with ISO.