Diacerhein and rhein reduce the ICE-induced IL-1beta and IL-18 activation in human osteoarthritic cartilage

Management of Skin Lesions in Patients with Epidermolysis Bullosa by Topical Treatment: Systematic Review and Meta-Analysis

Epidermolysis bullosa (EB) is the overarching term for a set of rare inherited skin fragility disorders that result from mutations in at least 20 different genes. Currently, there is no cure for any of the EB subtypes associated with various mutations. Existing therapies primarily focus on alleviating pain and promoting early wound healing to prevent potential complications. Consequently, there is an urgent need for innovative therapeutic approaches. The objective of this research was to assess the efficacy of various topical treatments in patients with EB with the goal of achieving wound healing. A secondary objective was to analyse the efficacy of topical treatments for symptom reduction. A literature search was conducted using scientific databases, including The Cochrane Library, Medline (Pubmed), Web of Science, CINHAL, Embase, and Scopus. The protocol review was registered in PROSPERO (ID: 418790), and inclusion and exclusion criteria were applied, resulting in the selection of 23 articles. Enhanced healing times were observed compared with the control group. No conclusive data have been observed on pain management, infection, pruritus episodes, and cure rates over time. Additionally, evidence indicates significant progress in gene therapies (B-VEC), as well as cell and protein therapies. The dressing group, Oleogel S-10, allantoin and diacerein 1%, were the most represented, followed by fibroblast utilisation. In addition, emerging treatments that improve the patient's innate immunity, such as calcipotriol, are gaining attention. However, more trials are needed to reduce the prevalence of blistering and improve the quality of life of individuals with epidermolysis bullosa.

Efficacy of Interleukin-1β Inhibitor on Dry Eye Disease in Patients with Degenerative Arthritis

Purpose

To evaluate diacerein (interleukin-1β inhibitor) efficacy on ocular surface disease (OSD).

Patients and Methods

This prospective observational study included patients who received diacerein for osteoarthritis and had dry eye (DE). The primary outcome was corneal staining score. Secondary outcomes were ocular surface disease index (OSDI) score, tear breakup time (TBUT), tear osmolarity (Osm), Schirmer's test results, interleukin-1α (IL-1α), interleukin-1β (IL-1β), and interleukin-1 receptor antagonist (IL-1Ra) levels in tears. All measurements were done at baseline and 2-month follow-up visits. Linear mixed models were used to examine the effect of all parameters, and log-transformed models were used for IL-1α, IL-1β, and IL-1Ra analyses.

Results

Thirty-four patients (31 females and 3 males) were enrolled. The corneal staining score improved by 1.29 points (P=0.022, 95% confidence interval [95% CI] 0.19 to 2.40) after 2 months, and the OSDI score improved by 17.2 points (P<0.001, 95% CI 10.82 to 23.58) but TUBT decreased by 0.66 seconds (P=0.021, 95% CI 0.10 to 1.22). No significant differences were observed in the tear Osm and Schirmer's test. IL-1Ra demonstrated no statistical difference, IL-1α was significantly increased by 80% (P=0.260), and IL-1β was significantly decreased by 99.21% (P<0.001).

Conclusion

Diacerein can improve corneal staining and decrease IL-1β levels in tears, which reflects better DE symptoms. Diacerein may be a promising alternative treatment for patients with OSD and osteoarthritis.

The Effects of the Combination of Rhein and Platelet-Rich Plasma on Human Articular Chondrocytes

BACKGROUND

The presence of side effects and low bioavailability of rhein has limited its use in the treatment of osteoarthritis. We aimed to evaluate the in vitro response of human articular chondrocytes to the presence of the combination of platelet-rich plasma (PRP) and rhein.

METHODS

Solutions of rhein were prepared to assess solubility and select a working concentration. A stimulus with interleukin-1β (IL-β, 10 ng/mL) was induced for 24 h on human chondrocytes. Five treatment groups were established: control, IL-β control, PRP, rhein, and PRP + rhein. Cell viability, cell migration, nitric oxide (NO) production, tumor necrosis factor-α (TNF-α), and gene expression analyses were carried out.

RESULTS

A concentration of 50 mg/L was selected after a dose-response curve assay. Both NO and tumor TNF-α production significantly decreased after PRP and PRP + rhein treatments at 24 and 48 h. The wound healing assay revealed a significant stimulation of migration after 72 h with the PRP and PRP + rhein treatments. Expression of IL-1β, IL-6, MMP-13, and ADAMTS-5 was significantly downregulated, particularly after treatment with the combination of PRP + rhein.

CONCLUSIONS

Much of the determinations denoted a better performance of the combination of PRP and rhein in decreasing the levels of the different targets evaluated; however, this was not great enough to detect a significant difference in comparison with the PRP treatment alone.

Diacerein versus non-steroidal anti-inflammatory drugs in the treatment of knee osteoarthritis: a meta-analysis

BACKGROUND

Knee osteoarthritis (KOA) is a common musculoskeletal condition affecting millions of people worldwide and posing a significant challenge to clinicians and researchers. Emerging evidence suggests that the multifaceted symptomatology of KOA may be alleviated by diacerein. With this in mind, we conducted a systematic review and meta-analysis to evaluate the efficacy and safety of diacerein in patients with KOA.

METHODS

We systematically searched Embase, PubMed, Cochrane Library, Web of Science, Chinese Biomedical Literature Database (CBM), Wanfang Database (WanFang), China National Knowledge Infrastructure (CNKI), and China Science and Technology Journal Database (VIP) from their inception to August 2022 for randomized controlled trials (RCTs) of diacerein intervention on patients with KOA. Two reviewers independently performed the selection of eligible studies and the extraction of relevant data. The meta-analysis was performed using RevMan 5.4 and R 4.1.3 software tools. Depending on the type of outcome indicator selected, summary measures were expressed as mean differences (MD), standardized mean differences (SMD), or odds ratio (OR) with 95% confidence intervals (CI).

RESULTS

Twelve RCTs with 1732 patients were included. The results revealed that diacerein had comparable efficacy to non-steroidal anti-inflammatory drugs (NSAIDs) in reducing pain indicators such as Western Ontario and McMaster Universities Osteoarthritis Index (WOMAC) (SMD = 0.09, 95% CI [-0.10, 0.28], P = 0.34) and visual analogue scale (VAS) (SMD = -0.19, 95% CI [-0.65, 0.27], P = 0.42). However, diacerein outperformed NSAIDs in terms of global efficacy assessment by both patients and investigators (patients: 1.97, 95% CI [1.18, 3.29], P = 0.01; investigator: 2.18, 95% CI [0.99, 4.81], P = 0.05) at the end of treatment and sustained effectiveness in reducing WOMAC score and VAS score at four weeks after treatment. Moreover, there was no significant difference in adverse events incidence between the diacerein and NSAID groups. However, the GRADE evaluation indicated that the majority of the evidence quality was low.

CONCLUSIONS

The results of this study suggest that diacerein could potentially be considered as a pharmacological agent with significant efficacy for the treatment of patients suffering from KOA, offering a potential alternative treatment strategy for those patients contraindicated to NSAIDs. However, further high-quality studies with longer follow-up are needed to make more informed decisions about its efficacy in the treatment of KOA.

Evaluation of the Effects of Gamma Radiation Sterilization on Rhein-Loaded Biodegradable Microparticles for the Treatment of Osteoarthritis

In previous work, we reported on the design of biodegradable rhein-loaded PLGA microparticles for the treatment of osteoarthritis. Considering that a formulation designed for intra-articular administration must meet sterility requirements to guarantee its safety, in this study the effect of gamma radiation sterilization on these microparticles was evaluated. The size, morphology, and surface characteristics of the microparticles and the encapsulation efficiency of rhein were not affected by the sterilization process. Although DSC and PXRD analyses suggested otherwise, rhein release profiles were not altered by gamma radiation. The release of rhein from the microparticles was fitted to a Gompertz model. In conclusion, the results of this study suggest that gamma radiation is a suitable method for the sterilization of rhein-loaded PLGA microparticles to enable their intra-articular administration in order to provide a therapeutic solution to patients suffering from chronic joint diseases.

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

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

Rhein induces changes in the lysosomal compartment of HeLa cells

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

Diacerein ameliorates acetaminophen hepatotoxicity in rats via inhibiting HMGB1/TLR4/NF-κB and upregulating PPAR-γ signal

BACKGROUND

Acetaminophen (APAP) is a worldwide antipyretic as well as an analgesic medication. It has been extensively utilized during the outbreak of coronavirus 2019 (COVID-19). APAP misuse would lead to liver injury. Diacerein (DIA), an anthraquinone derivative, has antioxidant and inflammatory properties. Hence, this study attempted to evaluate the impact of DIA treatment on liver injury induced by APAP and its influence on nuclear factor-κB (NF-κB) /toll-like receptor 4 (TLR4)/high mobility group box-1(HMGB-1) signaling as well as the expression of peroxisome proliferator-activated receptor-gamma (PPAR-γ) expression.

METHODS

Male albino rats received 25 as well as 50 mg/kg/day DIA orally for seven days. One hour after the last administration, rats received APAP (1gm/kg, orally). For histopathological analysis, liver tissues and blood were collected, immunohistochemical (IHC) assay, biochemical assay, as well as quantitative real-time polymerase chain reaction (qRT-PCR).

RESULTS

DIA markedly reduced liver injury markers and ameliorated histopathological changes. Moreover, DIA dose-dependently alleviated oxidative stress status caused by APAP administration along with inflammatory markers, including the level of interleukin-1 beta (IL-1β), myeloperoxidase (MPO), tumor necrosis factor-alpha (TNF-α), and interleukin 6 (IL-6). Furthermore, DIA downregulated protein levels as well as mRNA of HMGB-1, TLR4, NF-κB p65 expression, and enhanced PPAR-γ expression. Moreover, DIA ameliorated apoptotic (Bax) and caspase-3 expressions and increased the anti-apoptotic (Bcl2) expression.

CONCLUSIONS

This study demonstrated that DIA exerts anti-apoptotic, anti-inflammatory, and antioxidant properties against liver injury induced by APAP that is attributed to inhibition of the HMGB1/TLR4/NF-κB pathway, besides upregulation of the expression of PPAR-γ.

Reversal of Epigenetic Peroxisome Proliferator-Activated Receptor-γ Suppression by Diacerein Alleviates Oxidative Stress and Osteoarthritis in Mice

Aims: The pathogenesis of osteoarthritis (OA) is characterized by oxidative stress (OS) and sustained inflammation that are substantially associated with epigenetic DNA methylation alterations of osteogenic gene expression. Diacerein as an anthraquinone anti-OA drug exhibits multiple chondroprotective properties, but less clarified pharmacological actions. Since anthraquinone contain an epigenetic modulating property, in this study we investigate whether the anti-OA functions of diacerein involve DNA methylation modulation and antioxidant signaling. Results: The OA mice incurred by destabilization of medial meniscus exhibited marked suppression of peroxisome proliferator-activated receptor-gamma (PPARγ), a chondroprotective transcription factor with anti-inflammation and OS-balancing properties, aberrant upregulations of DNA methyltransferase (DNMT)1/3a, and PPARγ promoter hypermethylation in knee joint cartilage. Diacerein treatment mitigated the cartilage damage and significantly inhibited the DNMT1/3a upregulation, the PPARγ promoter hypermethylation, and the PPARγ loss, and it effectively corrected the adverse expression of antioxidant enzymes and inflammatory cytokines. In cultured chondrocytes, diacerein reduced the interleukin-1β-induced PPARγ suppression and the abnormal expression of its downstream antioxidant enzymes in a gain of DNMT and PPARγ inhibition-sensitive manner, and in PPARγ knockout mice, the anti-OA effects of diacerein were significantly reduced. Innovation: Our work reveals a novel anti-OA pharmacological property of diacerein and identifies the aberrant DNMT elevation and the resultant PPARγ suppression as an important epigenetic pathway that mediates diacerein's anti-OA activities. Conclusion: DNA methylation aberration and the resultant PPARγ suppression contribute significantly to epigenetic OA pathogenesis, and targeting PPARγ suppression via DNA demethylation is an important component of diacerein's anti-OA functions. Antioxid. Redox Signal. 37, 40-53.

Rhubarb free anthraquinones improved mice nonalcoholic fatty liver disease by inhibiting NLRP3 inflammasome

Background

Nonalcoholic fatty liver disease (NAFLD) is one of the most common chronic liver diseases and has become a huge public health issue worldwide. Inhibition of nucleotide oligomerization domain-like receptors containing pyrin domain 3 (NLRP3) inflammasome is a potential therapeutic strategy for NAFLD. Currently, there are no drugs targeting NLRP3 inflammasome for clinical treatment of NAFLD. In this study, we explored the efficacy and mechanism of rhubarb free anthraquinones (RFAs) in treating NAFLD by inhibiting NLRP3 inflammasome.

Methods

First, NLRP3 inflammasome was established in mouse bone marrow-derived macrophages (BMDMs), Kuffer cells and primary hepatocytes stimulated by lipopolysaccharide (LPS) and inflammasome inducers to evaluate the effect of RFAs on inhibiting NLRP3 inflammasome and explore the possible mechanism. Further, Mice NAFLD were established by methionine and choline deficiency diet (MCD) to verify the effect of RFAs on ameliorating NAFLD by inhibiting NLRP3 inflammasome.

Results

Our results demonstrated that RFAs including rhein/diacerein, emodin, aloe emodin and 1,8-dihydroxyanthraquinone inhibited interleukin-1 beta (IL-1β) but had no effect on tumor necrosis factor-alpha (TNF-α). Similar results were also showed in mouse primary hepatocytes and Kuffer cells. RFAs inhibited cleavage of caspase-1, formation of apoptosis-associated speck-like protein containing a CARD (ASC) speck, and the combination between NLRP3 and ASC. Moreover, RFAs improved liver function, serum inflammation, histopathological inflammation score and liver fibrosis.

Conclusions

RFAs including rhein/diacerein, emodin, aloe emodin and 1,8-dihydroxyanthraquinone ameliorated NAFLD by inhibiting NLRP3 inflammasome. RFAs might be a potential therapeutic agent for NAFLD.

Graphical Abstract

Supplementary Information

The online version contains supplementary material available at 10.1186/s12967-022-03495-4.

Diacerein/rhein as NLRP3 blockers used in treating osteoarthritis clinically.

RFAs including rhein/diacerein are main components of Rhubarb contained in yinchenhao decoction.

RFAs inhibited the transcription and assembly of NLRP3 inflammasome.

RFAs, Rhubarb and yinchenhao decoction improved NAFLD probably by inhibiting NLRP3 inflammasome.

RFAs are the potential NLRP3 inflammasome blockers for treating NAFLD clinically.

Chondroitin sulfate-functionalized lipid nanoreservoirs: a novel cartilage-targeting approach for intra-articular delivery of cassic acid for osteoarthritis treatment

Novel intra-articular nanoreservoirs were implemented employing different cartilage targeting approaches to improve cartilage bioavailability of a chondroprotective drug, cassic acid (CA), for effective amelioration of cartilage deterioration off-targeting CA gastrointestinal disorders. Herein, we compared active cartilage-targeting approach via chondroitin sulfate (CHS) functionalization versus passive targeting using positively charged nanoparticles to target negatively charged cartilage matrix. Firstly, CA integrated nanoreservoirs (CA-NRs) were fabricated based on ionic conjugation between CA and cationic hydrophobic surface modifier octadecylamine (ODA) and were further functionalized with CHS to develop CHS-CA-NRs. Confocal laser microscope was used to visualize the accumulation of nanoparticles into the cartilage tissue. Both targeting approaches promoted CA local cartilage availability and prolonged its residence time. Compared to passive targeted CA-NRs, active targeted CHS-CA-NRs showed higher fluorescence signals in proximity to and inside chondrocytes which lasted for up to 21 days. In MIA-osteoarthritic rats, CHS-CA-NRs showed superior antiosteoarthritic activity, exhibiting highest cartilage repair compared to CA-NRs. Additionally, CHS-CA-NRs significantly inhibited OA inflammatory cytokine, degradation enzyme and oxidative stress and improved cartilage matrix biosynthesis. Conclusively, CHS-CA-NRs improved OA repair showing a superior efficacy for articular cartilage targeting with CHS which could be a potential advance for OA therapy.

Therapeutic Potential of Diacerein in Management of Pain

Diacerein (DCN), an analogue of rhein (a glycosidal compound of natural origin), is currently used in the treatment of osteoarthritis and is given a fast-track designation for development to treat epidermolysis bullosa (EB). It is a nonsteroidal anti-inflammatory drug having disease-modifying properties in osteoarthritis and anti-inflammatory effects for the treatment of EB. Diacerein has a beneficial effect on pain relief and demonstrated antioxidant and anti-apoptotic effects, which are useful in renal disease, diabetes, and other disorders. This review discusses the possible mechanism of diacerein in the management of pain. The potential role of rhein and diacerein in the treatment of neuropathic, inflammatory and nociceptive pain is also reviewed. The effect of diacerein and rhein on mediators of pain, such as transient receptor potential cation channel subfamily V (TRPV1), Substance P, glutamate, inflammatory cytokines, nitric oxide, matrix metalloproteinases, histamine, palmitoylethanolamide, nuclear factor-kappa B (NFkB), and prostaglandin, has also been discussed. The data highlights the role of diacerein in neuropathic, nociceptive and inflammatory pain. Clinical trials and mechanism of action studies are needed to ascertain the role of diacerein, rhein or their analogues in the management of pain, alone or in combination with other approved therapies.

Cationic nanocarrier of rhein based on hydrophobic ion pairing approach as intra-articular targeted regenerative therapy for osteoarthritis

Cartilage deterioration is the hallmark of osteoarthritis (OA). Rapid clearance of intra-articularly injected drugs and inherent cartilage barrier properties represent enormous challenges facing the effective local OA therapy. Rhein (RH), a dihydroxy-anthraquinone acid molecule, possess a potential chondroprotective effect. However, RH suffers from poor oral bioavailability besides its gastrointestinal side effects. Herein, for the first time, we exploited cationic carriers to target anionic cartilage matrix to create a RH-reservoir within the cartilage matrix, improving RH therapeutic efficacy with reduced side effects. Firstly, we improved RH lipophilic characteristics employing hydrophobic ion pairing (HIP) to be efficiently loaded within lipid nanoparticles with slow-release properties. RH-HIP integrated solid lipid nanoparticles (RH-SLNs) rapidly penetrated through cartilage tissue and lasted for 3 weeks into healthy and arthritic rat joints. Furthermore, RH-SLNs significantly inhibited inflammatory response, oxidative stress and cartilage deterioration in MIA-arthritic rats. In conclusion, intra-articular cationic RH-SLNs represented a meaningful step towards OA therapy.

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.

Impaired macrophages and failure of steroidogenesis and spermatogenesis in rat testes with cytokines deficiency induced by diacerein

The role of cytokines in testicular function under normal conditions has not been completely understood. Here, we evaluated testicular macrophages (TM), steroidogenesis by Leydig cells (LC) and seminiferous tubules integrity in cytokines-deficient rat testes induced by diacerein, an anti-inflammatory drug that inhibits interleukin-1 (IL-1) and tumor necrosis factor-alpha (TNF-α). Male rats received daily 100 mg/kg of diacerein (DIAG; n = 8) or saline (CG; n = 8) for 30 days. Serum testosterone (T) levels were measured and the seminiferous tubule (ST) area, epithelial area (EA), frequency of damaged ST and number of Sertoli cells (SC) were evaluated. TUNEL method and immunoreactions for detection of pro-IL-1β, TNF-α, steroidogenic acute regulatory protein (StAR), 17β-hydroxysteroid dehydrogenase (17β-HSD), androgen receptor (AR) and scavenger receptor for hemoglobin-haptoglobin complexes (CD163), a TM marker, were performed. Testicular AR, 17β-HSD and IL-1β levels were detected by Western blot. Data were submitted to Student t test (p ≤ 0.05). In DIAG, T and testicular AR, 17β-HSD and IL-1β levels decreased significantly (p < 0.05). The number of TUNEL-positive interstitial cells increased and LC showed weak StAR, 17β-HSD and AR immunoexpression in association with reduced IL-1β immunoexpression and number of CD163-positive TM in the interstitial tissue from diacerein-treated rats. Numerous damaged ST were found in DIAG, and reduction in the EA were associated with germ cells death. Moreover, the number of SC reduced and weak AR and TNF-α immunoexpression was observed in SC and germ cells, respectively. The cytokines deficiency induced by diacerein impairs TM, LC and spermatogenesis, and points to a role of IL-1β in steroidogenesis under normal conditions. In the ST, the weak AR and TNF-α immunoexpression in SC and germ cells, respectively, reinforces the idea that TNF-α plays a role in the SC androgenic control.

The Metabolism and Pharmacokinetics of Rhein and Aurantio-Obtusin

BACKGROUND

Anthraquinones, rhein and aurantio-obtusin were isolated from the herb Duhaldea nervosa for the first time by our group, which were also found in plants that belong to the plant family Compositae. Anthraquinone compounds have a range of pharmacological activities such as anti-inflammatory, anti-cancer, antioxidation, anti-diabetes, etc. and can be used as a laxative, for liver protection, treatment of chronic renal failure, etc. However, in recent years, anthraquinones have been reported to be cytotoxic to the liver and kidneys. Therefore, it is very important to study the pharmacokinetics and metabolism of rhein and aurantio-obtusin, which are common ingredients in many traditional Chinese medicines (TCM). According to our research, the pharmacokinetics and metabolism of rhein and aurantio-obtusin are comprehensively summarized in the paper for the first time.

OBJECTIVE

The study provides comprehensive information on pharmacokinetics and metabolism of rhein and aurantio- obtusin in different Species; meanwhile, the aim of this review is also to provide a reference for a reasonable application of TCM enriched with these two ingredients.

METHODS

The metabolism and pharmacokinetics of rhein and aurantio-obtusin were searched by the Web of Science, PubMed, Google scholar and some Chinese literature databases.

RESULTS

Rhein and aurantio-obtusin exist mainly in the form of metabolites in the body. Rhein and aurantio-obtusin and its metabolites might be responsible for pharmacological effects in the body. Therefore, the significance of studying the in vivo metabolites of rhein and aurantio-obtusin is not only essential to clarify their pharmacological mechanism, but also to find new active compound ingredients. The metabolism of rhein is different in different species, so the toxicity effects of rhein may also be different after oral administration in different species; however, the metabolic profiles of aurantio-obtusin in the liver microsomes of different species are similar.

CONCLUSION

This paper not only provides detail regarding the pharmacokinetics of rhein and aurantio-obtusin, but it is anticipated that it will also facilitate further study on the metabolism of rhein and aurantio-obtusin.

Anti-inflammatory Effects and Mechanisms of Rhein, an Anthraquinone Compound, and Its Applications in Treating Arthritis: A Review

Inflammation is a defensive response of living tissues to damaging agents, which exists in two forms, acute inflammation and chronic inflammation, and chronic inflammation is closely related to arthritis. Currently, the commonly prescribed anti-inflammatory medications are greatly limited by high incidence of gastrointestinal erosions in the clinical applications. Rhein, a bioactive constituent of anthraquinone, exhibits excellent anti-inflammatory activities and therapeutic effects on arthritis with less gastrointestinal damages. Although there are numbers of studies on anti-inflammatory effects and mechanisms of rhein in the last few decades, to the best of our knowledge, only a few review articles pay attention to the interactive relationships of rhein on multiple inflammatory signaling pathways and cellular processes from a comprehensive perspective. Herein, we summarized anti-inflammatory effects and mechanisms of rhein and its practical applications in the treatment of arthritis, thereby providing a reference for its basic researches and clinical applications.

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.

Complexes of oxoplatin with rhein and ferulic acid ligands as platinum(iv) prodrugs with high anti-tumor activity

We herein designed two new Pt^IV prodrugs of oxoplatin (cis,cis,cis-[PtCl₂(NH₃)₂(OH)₂]), [Pt^IVCl₂(NH₃)₂(O₂C-FA)₂] (Pt-2) and [Pt^IVCl₂(NH₃)₂(O₂C-RH)₂] (Pt-3), by conjugating with ferulic acid (FA-COOH) and rhein (RH-COOH) which have well-known biological activities. Three other Pt(iv) complexes of [Pt^IVCl₂(NH₃)₂(O₂C-BA)₂] (Pt-1), [Pt^IVCl₂(NH₃)₂(O₂C-CA)₂] (Pt-4) and [Pt^IVCl₂(NH₃)₂(O₂C-TCA)₂] (Pt-5) (where BA-COOH = benzoic acid, CA-COOH = crotonic acid and TCA-COOH = trans-cinnamic acid) were also prepared for the comparative study. Like most Pt^IV prodrug complexes, the cytotoxicity of Pt-3 containing the biologically active rhein (RH-COOH) ligand against lung carcinoma (A549 and A549/DDP) cells was higher than those of Pt-1, Pt-2, Pt-4, cisplatin and Pt-5. Moreover, the cytotoxicity of Pt-3 in HL-7702 normal cells was lower than those of Pt^IV derivatives bearing BA-COOH, FA-COOH, TCA-COOH and CA-COOH ligands. The highly efficacious Pt-2 and Pt-3 were found to accumulate strongly in the A549/DDP cells, with the prodrug Pt-3 showing highest levels of penetration into the mitochondria. The prodrug Pt-3 effectively entered the A549/DDP cells and caused mitochondrial damage, significantly greater than Pt-2. In addition, the prodrug Pt-3 exhibited higher antitumor efficacy (inhibition rates (IR) = 67.45%) than Pt-2 (28.12%) and cisplatin (33.05%) in the A549/DDP xenograft mouse model. Thus, the prodrug Pt-3 containing the rhein (RH-COOH) ligand is a promising candidate drug targeting the mitochondria.

Proinflammatory cytokines and lipopolysaccharides up regulate MMP-3 and MMP-13 production in Asian elephant (Elephas maximus) chondrocytes: attenuation by anti-arthritic agents

Background

Osteoarthritis (OA), the most common form of arthritic disease, results from destruction of joint cartilage and underlying bone. It affects animals, including Asian elephants (Elephas maximus) in captivity, leading to joint pain and lameness. However, publications regarding OA pathogenesis in this animal are still limited. Therefore, this study aimed to investigate the effect of proinflammatory cytokines, including interleukin-1 beta (IL-1β), IL-17A, tumor necrosis factor-alpha (TNF-α), and oncostatin M (OSM), known mediators of OA pathogenesis, and lipopolysaccharides on the expression of cartilaginous degrading enzymes, matrix metalloproteinase (MMP)-3 and MMP-13, in elephant articular chondrocytes (ELACs) cultures. Anti-arthritic drugs and the active compounds of herbal plants were tested for their potential attenuation against overproduction of these enzymes.

Results

Among the used cytokines, OSM showed the highest activation of MMP3 and MMP13 expression, especially when combined with IL-1β. The combination of IL-1β and OSM was found to activate phosphorylation of the mitogen-activated protein kinase (MAPK) pathway in ELACs. Lipopolysaccharides or cytokine-induced expressions were suppressed by pharmacologic agents used to treat OA, including dexamethasone, indomethacin, etoricoxib, and diacerein, and by three natural compounds, sesamin, andrographolide, and vanillylacetone.

Conclusions

Our results revealed the cellular mechanisms underlying OA in elephant chondrocytes, which is triggered by proinflammatory cytokines or lipopolysaccharides and suppressed by common pharmacological or natural medications used to treat human OA. These results provide a more basic understanding of the pathogenesis of elephant OA, which could be useful for adequate medical treatment of OA in this animal.

IL-1 in osteoarthritis: time for a critical review of the literature

The concept of interleukin-1 (IL-1) as a target in osteoarthritis (OA) has been an attractive one for many years. It is a highly potent inducer of cartilage degradation, causing the induction of mRNA and controlling the bioavailability of disease-relevant proteases such as ADAMTS5 and MMP13. It drives synovitis and can induce other disease-relevant genes such as nerve growth factor, a key pain sensitiser in OA. However, the quality of evidence for its involvement in disease is modest. Descriptive studies have demonstrated expression of IL-1α and β in OA cartilage and elevated levels in the synovial fluid of some patients. Agnostic transcriptomic and genomic analyses do not identify IL-1 as a key pathway. In vivo models show a conflicting role for this molecule; early studies using therapeutic approaches in large animal models show a benefit, but most murine studies fail to demonstrate protection where the ligands (IL-1α/β), the cytokine activator (IL-1–converting enzyme), or the receptor (IL-1R) have been knocked out. Recently, a number of large double-blind randomised controlled clinical studies targeting IL-1 have failed. Enthusiasm for IL-1 as a target in OA is rapidly dwindling.

Trans-Cinnamaldehyde Inhibits IL-1β-Stimulated Inflammation in Chondrocytes by Suppressing NF-κB and p38-JNK Pathways and Exerts Chondrocyte Protective Effects in a Rat Model of Osteoarthritis

Objective

Trans-cinnamaldehyde (TCA), a compound from Cinnamomum cassia Presl, has been reported to have anti-inflammatory effect. However, its effect on cartilage degradation in osteoarthritis is unclear. This study is designed to examine the effects of TCA on cartilage in vitro and in vivo.

Material and Methods

SW1353 cells and human primary chondrocytes were treated with varying concentrations of TCA (2-20 μg/ml) for 2 h followed by IL-1β stimulation. Cell viability was examined by the MTT assay. Expression of MMP-1, MMP-3, MMP-13, ADAMTS-4, and ADAMTS-5 was examined by Western blot and RT-qPCR. Monosodium iodoacetate (MIA)-induced OA was established in rats to assess the chondrocyte protective effects of intraperitoneal injection of TCA (50 mg/kg).

Results

TCA at a concentration of 10 μg/ml had no significant effect on cell viability. MMP-1, MMP-3, MMP-13, ADAMTS-4, and ADAMTS-5 were decreased by TCA 2-10 μg/ml in a dose-dependent manner (all P<0.05). Pretreatment with TCA decreased the degradation of IκBα and increased the expression of p-IκBα, indicating that NF-κB inactivation was induced by TCA in IL-1β-stimulated SW1353 cells. Pretreatment with TCA decreased the levels of p-p38 and p-JNK, while the levels of p-ERK were not significantly affected. TCA 10 μg/ml significantly decreased expression levels of MMP-1, MMP-3, MMP-13, ADAMTS-4, and ADAMTS-5. In vivo results showed that TCA alleviated cartilage destruction and the OARSI scores.

Conclusion

TCA possesses anti-inflammatory effect in vitro and exerts chondrocyte protective effects in vivo, in which NF-κB and p38-JNK were involved.

Targeting of chondrocyte plasticity via connexin43 modulation attenuates cellular senescence and fosters a pro-regenerative environment in osteoarthritis

Osteoarthritis (OA), a chronic disease characterized by articular cartilage degeneration, is a leading cause of disability and pain worldwide. In OA, chondrocytes in cartilage undergo phenotypic changes and senescence, restricting cartilage regeneration and favouring disease progression. Similar to other wound-healing disorders, chondrocytes from OA patients show a chronic increase in the gap junction channel protein connexin43 (Cx43), which regulates signal transduction through the exchange of elements or recruitment/release of signalling factors. Although immature or stem-like cells are present in cartilage from OA patients, their origin and role in disease progression are unknown. In this study, we found that Cx43 acts as a positive regulator of chondrocyte-mesenchymal transition. Overactive Cx43 largely maintains the immature phenotype by increasing nuclear translocation of Twist-1 and tissue remodelling and proinflammatory agents, such as MMPs and IL-1β, which in turn cause cellular senescence through upregulation of p53, p16^INK4a and NF-κB, contributing to the senescence-associated secretory phenotype (SASP). Downregulation of either Cx43 by CRISPR/Cas9 or Cx43-mediated gap junctional intercellular communication (GJIC) by carbenoxolone treatment triggered rediferentiation of osteoarthritic chondrocytes into a more differentiated state, associated with decreased synthesis of MMPs and proinflammatory factors, and reduced senescence. We have identified causal Cx43-sensitive circuit in chondrocytes that regulates dedifferentiation, redifferentiation and senescence. We propose that chondrocytes undergo chondrocyte-mesenchymal transition where increased Cx43-mediated GJIC during OA facilitates Twist-1 nuclear translocation as a novel mechanism involved in OA progression. These findings support the use of Cx43 as an appropriate therapeutic target to halt OA progression and to promote cartilage regeneration.

Sheng-Di-Da-Huang Decoction Inhibited Inflammation Expressed in Microglia after Intracerebral Hemorrhage in Rats

Objects

Sheng-Di-Da-Huang Decoction was used as an effective hemostatic agent in ancient China. However, its therapeutic mechanism is still not clear. Inflammatory injury plays a critical role in ICH-induced secondary brain injury. After hemolysis, hematoma components are released, inducing microglial activation via TLR4, which initiates the activation of transcription factors (such as NF-κB) to regulate expression of proinflammatory cytokine genes. This study aimed to verify the anti-inflammatory effects of Sheng-Di-Da-Huang Decoction on ICH rats.

Materials and Methods

Intracerebral hemorrhage was induced by injection of bacterial collagenase (0.2 U) in rats. Neurological deficits, brain water content, Evans blue extravasation, expression of TLR4, NF-κB, Iba-1 positive cells (activated microglia), tumor necrosis factor-α (TNF-α), and interleukin-1β (IL-1β) were examined 1, 3, 7, and 14 days after collagenase injection. MR images were also studied.

Results

Sheng-Di-Da-Huang Decoction remarkably improved neurological function, reduced brain water content as well as Evans blue extravasation, downregulated expression of TLR4, NF-κB, TNF-α, and IL-1β, and inhibited microglial activation.

Conclusions

Sheng-Di-Da-Huang Decoction reduced inflammation reaction after ICH through inhibited inflammation expressed in microglia.

Critical role of IL-1α in IL-1β-induced inflammatory responses: cooperation with NF-κBp65 in transcriptional regulation

The IL-1 cytokines are considered among the first family of cytokines that orchestrate acute and chronic inflammatory diseases. Both IL-1β and IL-1α are members of the IL-1 family; however, their distinct roles in the inflammatory processes remain poorly understood. We explored the role of IL-1α in IL-1β-activated signaling pathways causing synovial inflammation in rheumatoid arthritis (RA). Using synovial fibroblasts isolated from RA joints, we found that IL-1β significantly stimulated IL-1α expression, which was selectively inhibited by blocking the NF-κB pathway. Knockdown of IL-1α using small interfering RNA abolished IL-1β-induced pro-IL-1α and pro-IL-1β expression and suppressed inflammation. Native and chromatin immunoprecipitation studies showed that IL-1α cooperates in NF-κBp65 binding to the distal region of IL-1α promoter and to the proximal region of IL-1β promoter upstream of the transcription start site to stabilize their gene transcription. Molecular dynamics simulation of IL-1α or IL-1β binding to IL-1 receptor showed distinct interaction sites that corroborate with the ability of IL-1α to differentially activate phosphorylation of signaling proteins compared with IL-1β. Our study highlights the importance of IL-1α in mediating IL-1β-induced inflammation in addition to maintaining its expression and providing a rationale for targeting IL-1α to minimize the role of IL-1β in inflammatory diseases like RA.-Singh, A. K., Fechtner, S., Chourasia, M., Sicalo, J., Ahmed, S. Critical role of IL-1α in IL-1β-induced inflammatory responses: cooperation with NF-κBp65 in transcriptional regulation.

Optimization of rhein-loaded polymeric nanoparticles using a factorial design and evaluation of the cytotoxic and anti-inflammatory effects

The aim of the work was to develop rhein loaded polymeric nanoparticles (R-PNPs). Nanoparticles were prepared by three methods, solvent emulsion-evaporation, double emulsion, and nanoprecipitation, by means of experimental design. Additionally, the effects of the best formulation on in vitro cytotoxicity and inflammation were evaluated. The solvent emulsion-evaporation method presented the highest encapsulation efficiency of the three techniques (38.41%), as well as had a mean diameter of 189.33 nm and a polydispersity index of less than 0.1. Despite efforts to optimize the encapsulation of rhein, the drug release from nanoparticles was close to 50% during the first 5 min, followed by a continuous release within 60 min. It was observed that macrophages exposed to the highest concentration of R-PNPs showed cell viability about 80% and at the lowest nanoparticle concentrations was closed to 100%. IL-1β in cell culture supernatants was decreased in the presence of R-PNPs and TNFα concentrations were lower than the sensitivity of the assay. ROS production was only inhibited with R-PNPs at concentrations of 2.5 and 5 μM. In conclusion, the solvent emulsion-evaporation was the best method evaluated to obtain nanoparticles with the desired specifications. It was possible to assess R-PNPs with low cytotoxicity and anti-inflammatory properties showed by the inhibition of IL-1β production and a low decrease in ROS production.

Developing anti-inflammatory therapeutics for patients with osteoarthritis

OA is the most common joint disorder in the world, but there are no approved therapeutics to prevent disease progression. Historically, OA has been considered a wear-and-tear joint disease, and efforts to identify and develop disease-modifying therapeutics have predominantly focused on direct inhibition of cartilage degeneration. However, there is now increasing evidence that inflammation is a key mediator of OA joint pathology, and also that the link between obesity and OA is not solely due to excessive load-bearing, suggesting therefore that targeting inflammation in OA could be a rewarding therapeutic strategy. In this review we therefore re-evaluate historical clinical trial data on anti-inflammatory therapeutics in OA patients, highlight some of the more promising emerging therapeutic targets and discuss the implications for future clinical trial design.

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.

Anthraquinones As Pharmacological Tools and Drugs

Anthraquinones (9,10-dioxoanthracenes) constitute an important class of natural and synthetic compounds with a wide range of applications. Besides their utilization as colorants, anthraquinone derivatives have been used since centuries for medical applications, for example, as laxatives and antimicrobial and antiinflammatory agents. Current therapeutic indications include constipation, arthritis, multiple sclerosis, and cancer. Moreover, biologically active anthraquinones derived from Reactive Blue 2 have been utilized as valuable tool compounds for biochemical and pharmacological studies. They may serve as lead structures for the development of future drugs. However, the presence of the quinone moiety in the structure of anthraquinones raises safety concerns, and anthraquinone laxatives have therefore been under critical reassessment. This review article provides an overview of the chemistry, biology, and toxicology of anthraquinones focusing on their application as drugs.

Diacerein: Benefits, Risks and Place in the Management of Osteoarthritis. An Opinion-Based Report from the ESCEO

Diacerein is a symptomatic slow-acting drug in osteoarthritis (SYSADOA) with anti-inflammatory, anti-catabolic and pro-anabolic properties on cartilage and synovial membrane. It has also recently been shown to have protective effects against subchondral bone remodelling. Following the end of the revision procedure by the Pharmacovigilance Risk Assessment Committee of the European Medicines Agency, the European Society for Clinical and Economic Aspects of Osteoporosis and Osteoarthritis (ESCEO) constituted a panel of 11 experts to better define the real place of diacerein in the armamentarium for treating OA. Based on a literature review of clinical trials and meta-analyses, the ESCEO confirms that the efficacy of diacerein is similar to that of non-steroidal anti-inflammatory drugs (NSAIDs) after the first month of treatment, and superior to that of paracetamol. Additionally, diacerein has shown a prolonged effect on symptoms of several months once treatment was stopped. The use of diacerein is associated with common gastrointestinal disorders such as soft stools and diarrhoea, common mild skin reactions, and, uncommonly, hepatobiliary disorders. However, NSAIDs and paracetamol are known to cause potentially severe hepatic, gastrointestinal, renal, cutaneous and cardiovascular reactions. Therefore, the ESCEO concludes that the benefit-risk balance of diacerein remains positive in the symptomatic treatment of hip and knee osteoarthritis. Furthermore, similarly to other SYSADOAs, the ESCEO positions diacerein as a first-line pharmacological background treatment of osteoarthritis, particularly for patients in whom NSAIDs or paracetamol are contraindicated.

Diacerein: A potential therapeutic drug for the management of experimental periodontitis in rats

Introduction:

Knowledge about the pathogenic process in the progression of periodontal disease indicates that the central cause of periodontal disease is the loss of a healthy balance between microbial virulence factors and the host’s inflammatory response. The aim of this study was to evaluate the potential effectiveness of diacerein as an anti-inflammatory drug in the management of experimental periodontitis in rats.

Methods:

The study included 60 albino rats that were divided into two groups. Periodontitis was induced in both groups. The drug group received systemic administration of diacerein, and the control group received a placebo. IL-1ß was measured two weeks after the induction of periodontitis and before the administration of the drug (baseline measurement), and it was measured again at the end of two and end of four weeks after scaling and root planning and diacerein administration.

Results:

The results indicated that there was a significant decrease in IL-1ß level in both groups. For the control group, there were significant decreases of the IL-1ß values from the baseline to two weeks and also from the baseline to four weeks, with p-values of 0.0001 for both comparisons. The same results were obtained for the drug group.

Conclusion:

It was concluded that it is likely that diacerein may play a therapeutic role as a potent anti-inflammatory drug in the management of periodontitis.

A Novel Synthesized Sulfonamido-Based Gallate-JEZ-C as Potential Therapeutic Agents for Osteoarthritis

Gallic acid (GA) and its derivatives are anti-inflammatory agents reported to have an effect on osteoarthritis (OA). However, GA has much weaker anti-oxidant effects and inferior bioactivity compared with its derivatives. We modified GA with the introduction of sulfonamide to synthesize a novel compound named JEZ-C and analyzed its anti-arthritis and chondro-protective effects. Comparison of JEZ-C with its sources i.e. GA and Sulfamethoxazole (SMZ) was also performed. Results showed that JEZ-C could effectively inhibit the IL-1-mediated induction of MMP-1 and MMP-13 and could induce the expression of TIMP-1, which demonstrated its ability to reduce the progression of OA. JEZ-C can also exert chondro-protective effects by promoting cell proliferation and maintaining the phenotype of articular chondrocytes, as evidenced by improved cell growth, enhanced synthesis of cartilage specific markers such as aggrecan, collagen II and Sox9. Meanwhile, expression of the collagen I gene was effectively downregulated, revealing the inhibition of chondrocytes dedifferentiation by JEZ-C. Hypertrophy that may lead to chondrocyte ossification was also undetectable in JEZ-C groups. The recommended dose of JEZ-C ranges from 6.25×10^-7 μg/ml to 6.25×10^-5 μg/ml, among which the most profound response was observed with 6.25×10^-6 μg/ml. In contrast, its source products of GA and SMZ have a weak effect not only in the inhibition of OA but also in the bioactivity of chondrocytes, which indicated the significance of this modification. This study revealed JEZ-C as a promising novel agent in the treatment of chondral and osteochondral lesions.

Rhein: A Review of Pharmacological Activities

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

Combination of diacerhein and antiepileptic drugs after local peripheral, and oral administration in the rat formalin test

Preclinical Research The present study was designed to evaluate the possible antinociceptive interaction between diacerhein and some antiepileptic drugs (carbamazepine, topiramate and gabapentin) on formalin-induced nociception. Diacerhein, each of the antiepileptics or a fixed dose-ratio combination of these drugs was assessed after local peripheral and oral administration in rats. lsobolographic analyses were used to define the interaction between drugs. Diacerhein, antiepileptic drugs (carbamazepine, topiramate and gabapentin) or their combinations yielded a dose-dependent antinociceptive effect when administered by both routes. Theoretical ED30 values for the combination estimated from the isobolograms were obtained as follows: diacerhein-carbamazepine (85.99 ± 7.07 μg/paw; 56.53 ± 4.56 mg/kg po), diacerhein-topiramate (197.97 ± 22.90 μg/paw; 13.06 ± 2.44 mg/kg po) and diacerhein-gabapentin (96.87 ± 17.73 μg/paw; 17.90 ± 4.70 mg/kg p.o.) for the local peripheral and oral administration routes, respectively. These values were significantly higher than the experimentally obtained ED30 values: diacerhein-carbamazepine (49.33 ± 3.37 μg/paw; 35.49 ± 7.91 mg/kg po), diacerhein-topiramate (133.00 ± 39.10 μg/paw; 8.87 ± 1.46 mg/kg po) and diacerhein-gabapentin (70.98 ± 14.73 μg/paw; 10.95 ± 3.23 mg/kg po). The combinations produced their antinociceptive effects without motor impairment in the rotarod test indicating synergistic interactions with a good side effect profile.

Chondroprotective Activity of Murraya exotica through Inhibiting β -Catenin Signaling Pathway

Osteoarthritis (OA) is a degenerative joint disease that affects millions of people. Currently, there is no effective drug treatment for it. The purpose of this study is to investigate the chondroprotective effects of Murraya exotica (L.) on OA. The rat OA models were duplicated to prepare for separating OA chondrocytes, synovial fluid (SF), and serum containing M. exotica (50 mg/kg, 100 mg/kg, and 200 mg/kg), M. exotica showed the activity of decreasing the contents of TNF-α and IL-1β in SF and the chondrocyte apoptosis in a dose-dependent manner. To investigate the probable mechanism, quantitative real-time polymerase chain reaction (qRT-PCR) and western blotting were used to determine gene expression and protein profiles, respectively. The results reveal that M. exotica can downregulate mRNA and protein expressions of β-catenin and COX-2 and reporter activity significantly. Conclusively, M. exotica exhibits antiapoptotic chondroprotective activity probably through inhibiting β-catenin signaling.

Topical diacerein for epidermolysis bullosa: a randomized controlled pilot study

Blistering in epidermolysis bullosa simplex type Dowling-Meara (EBS-DM) is associated with an inflammatory phenotype, which can be disrupted by diacerein in vitro. In this pilot study we hypothesized, that a topical formulation of diacerein 1% reduces blistering. Five patients initially applied diacerein underneath both armpits. Then, each participant received 1% diacerein-cream for one armpit, and placebo for the other (randomized withdrawal). The number of blisters was reduced significantly (left: -78%; right: -66% of baseline) within two weeks and remained significantly below the initial level even during withdrawal in four patients. These findings point to a relevant effect of diacerein and provide important information for a confirmative study.

Tetrandrine Inhibits the Wnt/ β -Catenin Signalling Pathway and Alleviates Osteoarthritis: An In Vitro and In Vivo Study

There is currently no effective drug treatment for the early phase of osteoarthritis (OA), one of the most common senile diseases. The goal of this study was to investigate the protective effect of the tetrandrine (Tet) on OA, in vitro and in vivo. In an in vitro experiment, quantitative real-time polymerase chain reaction (qRT-PCR) was used to investigate changes in gene expression upon the addition of Tet in chondrocytes processed with IL-1β; changes in protein profiles were assessed by Western blotting. In vivo, to determine whether Tet has the protective effects on articular cartilage, a rabbit anterior cruciate ligament transaction model of OA was established. Expression of matrix metalloproteinase and β-catenin genes increased significantly, while that of tissue inhibitor of metalloproteinase-1 decreased significantly in the OA group both in vivo and in chondrocytes. However, the changes of expression were reversed by Tet, and there was less cartilage degradation in vivo compared with the OA group, as assessed by histological and macroscopic observations. Thus, Tet may play a useful role in the treatment of OA through the Wnt/β-catenin signalling pathway and has potential for the treatment of OA.

Effects of diacerein at the molecular level in the osteoarthritis disease process

In osteoarthritis (OA), the alterations in joint tissues are numerous and involve morphological, biochemical and metabolic changes and an upregulation of the inflammatory pathways. The focus of this article is a brief narrative review of the effects of diacerein, an antirheumatic drug from the anthraquinone chemical class, and its active metabolite, rhein, on the factors that participate in the complex interaction between OA tissues and cells leading to the progression of joint structural changes.

Diacerein decreases visceral pain through inhibition of glutamatergic neurotransmission and cytokine signaling in mice

The present study evaluated the antinociceptive effect of the pro-inflammatory cytokines inhibitor diacerein in mice and its possible mechanism of action. The antinociception produced by diacerein was tested at different sites of action, moreover selective antagonists or agonists were used to identify the mechanism that may be involved in its antinociceptive action against acetic acid-induced visceral pain. Diacerein administered systemically (intraperitoneal [i.p.] or intra-gastric [i.g.] routes), supra-spinally (i.c.v.), spinally (i.t.) or peripherally (in association with the irritant agent) inhibited the visceral nociception induced by acetic acid in mice. Interestingly, diacerein treatment (25 mg/kg, i.p. or 50 mg/kg, i.g.) produced long-lasting (for up to 4 h) inhibition of acetic acid-induced nociception. Intraperitoneal treatment of mice with diacerein (25.0 mg/kg) inhibited somatic nociception induced by i.t. injection of glutamate, NMDA, kainate, and trans-ACPD but not that caused by AMPA. Diacerein (5.0-25.0 mg/kg) also produced dose related inhibition of interleukin-1β (IL-1β) and tumor necrosis factor alpha (TNF-α) induced nociception. These results indicate that diacerein produces antinociception by inhibiting glutamatergic transmission through both ionotropic and metabotropic receptors as well as activity of pro-inflammatory cytokines.

Diacerein: a potential therapeutic drug for periodontal disease

Periodontal diseases are chronic inflammatory diseases characterized by the destruction of the tooth-supporting structures. They are the most prevalent form of bone pathology in humans and act as a modifying factor of the systemic health of patients. Accumulating evidence has provided insight into mechanisms of periodontal inflammation revealing that oral pathogens induce inflammatory cascades, including a variety of cytokines produced by different cell types, which promotes host-mediated tissue destruction. Cytokine networks established in diseased periodontal tissues are extremely complex, and substances regulating immuno-inflammatory reactions and signaling pathways, in addition to traditional periodontal treatment, could potentially be targeted as an approach for prevention and treatment of periodontal diseases. Diacerein, a purified anthraquinone derivative, was derived originally from plants with profound anti-inflammatory and analgesic activities. Its wide range of biological activities have been applied and discussed for several decades; however, studies of diacerein have mainly concentrated on effects on joint-derived tissues/cells, which suggest a beneficial role in osteoarthritis treatment. Diacerein reduces association of the IL-1 receptor to form heterodimer complexes, repressing IL-1 and its related downstream events and impairing active IL-1 release due to the inhibition of the IL-1-converting enzyme (ICE). To date, there are no reports describing the therapeutic effect of diacerein for treatment of periodontitis. Given the involvement of inflammation and occurrence of tissue destruction in periodontal disease, we propose that diacerein might be a promising biological drug for periodontal disease due to its therapeutic advantages. In addition, we hypothesize that the underlying mechanisms might involve the capacity of diacerein to selectively inhibit signal transduction to affect the cytokine profiles and, consequently, produce the outcome of ameliorating disease breakdown.

Combined effect of subchondral drilling and hyaluronic acid with/without diacerein in full-thickness articular cartilage lesion in rabbits

The osteochondral healing potential of hyaluronic acid (HA) plus diacerein was evaluated in subchondral-drilling- (SCD-) induced fibrocartilage generation in rabbits. A full-thickness chondral defect was created along the patellar groove of both knees and then SCD was subsequently performed only in the left knee. A week later, the rabbits were allocated into 3 groups to receive weekly intra-articular (IA) injection for 5 weeks with normal saline solution (NSS) (group 1) or with HA (group 2 and group 3). Starting at the first IA injection, rabbits were also gavaged daily for 9 weeks with NSS (group 1 and group 2) or with diacerein (group 3). The animals were then sacrificed for evaluation. The newly formed tissue in SCD lesions showed significantly better histological grading scale and had higher content of type II collagen in HA-treated group compared to NSS control. In addition, adding oral diacerein to HA injection enhanced healing potential of HA.

Developmental mechanisms in articular cartilage degradation in osteoarthritis

Osteoarthritis is the most common arthritic condition, which involves progressive degeneration of articular cartilage. The most recent accomplishments have significantly advanced our understanding on the mechanisms of the disease development and progression. The most intriguing is the growing evidence indicating that extracellular matrix destruction in osteoarthritic articular cartilage resembles that in the hypertrophic zone of fetal growth plate during endochondral ossification. This suggests common regulatory mechanisms of matrix degradation in OA and in the development and can provide new approaches for the treatment of the disease by targeting reparation of chondrocyte phenotype.

Diacerein decreases TNF-alpha and IL-1beta levels in peritoneal fluid and prevents Baker's yeast-induced fever in young rats

OBJECTIVE

To investigate the effect of diacerein, an anti-inflammatory drug, on body temperature and protocols of fever induction in male Wistar rats.

METHODS

The effect of diacerein (5.0 mg/kg, s.c.) on rectal temperature (T (R)) changes induced by Baker's yeast (0.135 g/kg, i.p.) and PGE(2) (10 ng/animal, i.t.) was evaluated. T (R) changes were recorded over time. The leukocyte count and TNF-alpha and IL-1beta content were evaluated in the peritoneal fluid by means of optical microscopy and enzyme immunoassay (ELISA kits), respectively.

RESULTS

The administration of diacerein to febrile animals attenuated Baker's yeast-induced fever but did not alter prostaglandin E(2)-induced fever. Diacerein prevented the development of Baker's yeast-induced fever and significantly attenuated the increase in peritoneal leukocytes and decreased IL-1beta and TNF-alpha levels in peritoneal fluid.

CONCLUSIONS

These data suggest that diacerein partially protects against Baker's yeast-induced fever and peritoneal leukocyte migration, and indicate that this effect appears to be due to inhibition of release of cytokines (such as TNF-alpha and IL-1beta).