Inhibitory effect of the antimalarial agent artesunate on collagen-induced arthritis in rats through nuclear factor kappa B and mitogen-activated protein kinase signaling pathway

Dihydroartemisinin inhibits catabolism in rat chondrocytes by activating autophagy via inhibition of the NF-κB pathway

Osteoarthritis is a disease with inflammatory and catabolic imbalance in cartilage. Dihydroartemisinin (DHA), a natural and safe anti-malarial agent, has been reported to inhibit inflammation, but its effects on chondrocytes have yet to be elucidated. We investigated the effects of DHA on catabolism in chondrocytes. Viability of SD rats chondrocytes was analyzed. Autophagy levels were determined via expression of autophagic markers LC3 and ATG5, GFP-LC3 analysis, acridine orange staining, and electron microscopy. ATG5 siRNA induced autophagic inhibition. Catabolic gene and chemokine expression was evaluated using qPCR. The NF-κB inhibitor SM7368 and p65 over-expression were used to analyze the role of NF-κB pathway in autophagic activation. A concentration of 1 μM DHA without cytotoxicity increased LC3-II and ATG5 levels as well as autophagosomal numbers in chondrocytes. DHA inhibited TNF-α-induced expression of MMP-3 and -9, ADAMTS5, CCL-2 and -5, and CXCL1, which was reversed by autophagic inhibition. TNF-α-stimulated nuclear translocation and degradation of the p65 and IκBα proteins, respectively, were attenuated in DHA-treated chondrocytes. NF-κB inhibition activated autophagy in TNF-α-treated chondrocytes, but p65 over-expression reduced the autophagic response to DHA. These results indicate that DHA might suppress the levels of catabolic and inflammatory factors in chondrocytes by promoting autophagy via NF-κB pathway inhibition.

Discovery of novel small molecule inhibitors of cardiac hypertrophy using high throughput, high content imaging

Chronic cardiac hypertrophy is maladaptive and contributes to the pathogenesis of heart failure. The objective of this study was to identify small molecule inhibitors of pathological cardiomyocyte hypertrophy. High content screening was performed with primary neonatal rat ventricular myocytes (NRVMs) cultured on 96-well plates and treated with a library of 3241 distinct small molecules. Non-toxic hit compounds that blocked hypertrophy in response to phenylephrine (PE) and phorbol myristate acetate (PMA) were identified based on their ability to reduce cell size and inhibit expression of atrial natriuretic factor (ANF), which is a biomarker of pathological cardiac hypertrophy. Many of the hit compounds are existing drugs that have not previously been evaluated for benefit in the setting of cardiovascular disease. One such compound, the anti-malarial drug artesunate, blocked left ventricular hypertrophy (LVH) and improved cardiac function in adult mice subjected to transverse aortic constriction (TAC). These findings demonstrate that phenotypic screening with primary cardiomyocytes can be used to discover anti-hypertrophic lead compounds for heart failure drug discovery. Using annotated libraries of compounds with known selectivity profiles, this screening methodology also facilitates chemical biological dissection of signaling networks that control pathological growth of the heart.

Immune suppressive properties of artemisinin family drugs

Artemisinin and its derivatives are the first-line antimalarial drugs, and have saved millions of lives across the globe, especially in developing world. The discovery of artemisinin by Youyou Tu was awarded the 2015 Nobel Prize in Physiology or Medicine. In addition to treating malaria, accumulating evidences suggest that artemisinin and its derivatives also possess potent anti-inflammatory and immunoregulatory properties. We recently showed that artesunate, an artemisinin analog, dramatically ameliorated autoimmune arthritis by selectively diminishing germinal center B cells. Herein, we review the immunosuppressive properties of artemisinin family drugs and the potential underlying mechanisms.

Artesunate interfere in modulation of Foxp3 expression in synovial cells in collagen-induced arthritis rats

OBJECTIVE

To investigate the expression and significance of forkhead/winged helix (Foxp3) in rat synovial cells in collagen-induced arthritis rats after artesunate interventions.

METHODS

A male Wistar rat model of type II collagen-induced arthritis (CIA) was established. The synovia was removed, and synovial cells were cultured for 5-7 generations. The cells were divided into a normal control group, a CIA model group, artesunate groups at different concentrations (5, 10, and 20 ng/mL), and a hydroxychloroquine group. The expressions of the Foxp3 gene in the groups were detected by reverse transcription polymerase chain reaction, and their protein expressions were detected by western blotting.

RESULTS

In the drug intervention and CIA model groups, Foxp3 gene and protein expressions increased. The Foxp3 gene and protein expressions in the drug intervention groups were higher than those in the CIA model group, and fiber-like synovial cells numbers decreased. Foxp3 in the artesunate group was expressed at a greater level than the levels expressed in the control groups (P<0.05). Significantly increased of expression was observed in the 20 ng/mL artesunate group compared with the model group (P<0.05).

CONCLUSIONS

Artesunate could increase the expression of Foxp3 in a dose-dependent manner, and thus reduce pannus formation and erosion of cartilage and bone to prevent lesions from rheumatoid arthritis.

Artesunate inhibits type I interferon-induced production of macrophage migration inhibitory factor in patients with systemic lupus erythematosus

OBJECTIVE

Macrophage migration inhibitory factor (MIF) is a key regulator of both atherosclerosis and systemic lupus erythematosus (SLE), yet factors leading to its overproduction remain unclear. To explore regulation of MIF in SLE, we studied effects and potential mechanisms of type I interferon (IFN) and artesunate (ART), an antimalarial agent extracted from Chinese herbs, on levels of MIF.

METHODS

Serum and peripheral blood cells from SLE patients and healthy controls were measured for MIF levels by ELISA and type I IFN-inducible gene expressions by real-time PCR, respectively, and assessed for associations by Spearman correlation. ART was added to human umbilical vein endothelial cell (HUVEC) cultures with or without prior IFNα-1b stimulation and to SLE peripheral blood mononuclear cell (PBMC) cultures. Protein levels of STATs and phosphorylated (p-) STATs in HUVECs were determined by Western blotting.

RESULTS

Serum MIF levels were elevated in SLE patients and positively associated with disease activity (r = 0.86, p < 0.0001), accumulated damage (r = 0.34, p < 0.05), and IFN scores in SLE PBMCs (r = 0.74, p = 0.0002). The addition of IFNα-1b promoted MIF production in a time- and dose-dependent manner in HUVEC cultures. ART could inhibit expressions of IFN-inducible genes (LY6E and ISG15) in both HUVEC and SLE PBMC cultures, and suppress MIF production and over-expression of p-STAT1, but not p-STAT3 or STAT5, induced by IFNα-1b stimulation. IFNγ-induced expression of p-STAT1 in HUVECs was not inhibited by ART.

CONCLUSION

MIF could be regulated by type I IFN in SLE patients. ART counteracts the effect of IFNα to inhibit MIF production by blocking STAT1 phosphorylation and thus may have therapeutic potential for SLE-associated atherosclerosis.

Efficacy of Mitochondrial Antioxidant Plastoquinonyl-decyl-triphenylphosphonium Bromide (SkQ1) in the Rat Model of Autoimmune Arthritis

Rheumatoid arthritis is one of the most common autoimmune diseases. Many antioxidants have been tested in arthritis, but their efficacy was, at best, marginal. In this study, a novel mitochondria-targeted antioxidant, plastoquinonyl-decyl-triphenylphosphonium bromide (SkQ1), was tested in vivo to prevent and cure experimental autoimmune arthritis. In conventional Wistar rats, SkQ1 completely prevented the development of clinical signs of arthritis if administered with food before induction. Further, SkQ1 significantly reduced the fraction of animals that developed clinical signs of arthritis and severity of pathological lesions if administration began immediately after induction of arthritis or at the onset of first symptoms (day 14 after induction). In specific pathogen-free Wistar rats, SkQ1 administered via gavage after induction of arthritis did not reduce the fraction of animals with arthritis but decreased the severity of lesions upon pathology examination in a dose-dependent manner. Efficacious doses of SkQ1 were in the range of 0.25-1.25 nmol/kg/day (0.13-0.7 μg/kg/day), which is much lower than doses commonly used for conventional antioxidants. SkQ1 promoted apoptosis of neutrophils in vitro, which may be one of the mechanisms underlying its pharmacological activity. Considering its low toxicity and the wide therapeutic window, SkQ1 may be a valuable additional therapy for rheumatoid arthritis.

Artesunate Ameliorates Experimental Autoimmune Encephalomyelitis by Inhibiting Leukocyte Migration to the Central Nervous System

BACKGROUND AND AIMS

Experimental autoimmune encephalomyelitis (EAE) is T-cell-dependent disease of the central nervous system (CNS) of mice. This model resembles multiple sclerosis (MS) in many aspects. Therapies that focus in the modulation of the immune response and cellular infiltration in the CNS present best effects in the clinics. Artesunate (Art) is a semi-synthetic sesquiterpene derivative from artemisinin and has been shown to reduce the clinical signs of autoimmune disease models through mechanisms not yet understood. In this study, we aimed to evaluate whether administration of Art would ameliorate EAE.

METHODS AND RESULTS

C57BL6 mice were immunized with MOG35-55 peptide to induce EAE. At the same time, Art treatment started (3 mg/kg/day via i.p.) for five consecutive days. We found that Art treatment reduced the clinical signs of EAE and that correlated with a reduced infiltration of cells in the CNS. Disease amelioration did not correlate with immunomodulation as recall responses, leukocyte subpopulations, and gene expression analysis were similar among treated and untreated mice. Ultimately, further analysis provided data indicating that a possible mechanism of action for Art is dependent on the cellular migration to the CNS.

CONCLUSIONS

Artesunate reduces the severity of EAE by inhibiting migration of pathogenic T cells to the CNS.

The treatment of rheumatoid arthritis using Chinese medicinal plants: From pharmacology to potential molecular mechanisms

ETHNOPHARMACOLOGICAL RELEVANCE

Rheumatoid arthritis (RA) is a common worldwide public health problem. Traditional Chinese Medicine (TCM) achieved some results to some extent in the treatment of rheumatoid arthritis (RA). Especially in China, TCM formulas are used in the clinic because of their advantages. Some of these TCM formulas have been used for thousands of years in ancient China, they pays much attention to strengthening healthy qi, cleaning heat, and wet, activating blood, etc. So TCM in anti-RA drug is considered as a simple and effective method. In addition, TCM are also traditionally used as extracts and many Chinese herbs which are considered to be effective for RA. With the advancement of technologies and research methods, researchers have devoted themselves to exploring new therapeutic materials from troves of TCM. The components of TCM are identified and purified, which include alkaloids, coumarins, flavonoids, saponins and so on. However, little or no review works are found in the research literature on the anti-RA drugs from TCM. The present review aims to provide systematically reorganized information on the ethnopharmacology, phytochemistry and pharmacology of TCM used traditionally against RA. The information recorded in this review will provide new directions for researchers in the future.

MATERIALS AND METHODS

Relevant scientific literatures were collected from Chinese traditional books and Chinese Pharmacopoeia. Several important pharmacology data, clinical observations, animal experiments on effects of anti-RA drugs from TCM and their mechanisms were extracted from a library and electric search (Pubmed, PubChem Compound, Science Direct, Spring Link, Elsevier, Web of Science, CNKI, Wan Fang, Bai du, The Plant List, etc.). We collected information published between 2002 and 2015 on Chinese medicine in the treatment of RA. Information was also acquired from local classic herbal literature, conference papers, government reports, and PhD and MSc dissertations.

RESULTS

This review mainly introduces the current research on anti-RA TCM formulas, extracts and compounds from TCM, pharmacological data and potential mechanisms (inhibit osteoclast proliferation, suppress fibroblast-like synoviocytes (FLSs) growth, decrease the expression of inflammatory cytokines, blocking signal pathways, etc.).

CONCLUSIONS

TCM, as a multi-component and multi-target approach, which is a perfect match with the holistic concept of systems biology, is applicable in the treatment of RA. The synergistic connections of Chinese herbs and mechanisms of related active compounds on RA increase the trust for TCM. TCM as alternative remedies for RA not only has an important position in the world market, but also has an irreplaceable role in the treatment of RA in future.

Untargeted Proteomics and Systems-Based Mechanistic Investigation of Artesunate in Human Bronchial Epithelial Cells

The antimalarial drug artesunate is a semisynthetic derivative of artemisinin, the principal active component of a medicinal plant Artemisia annua. It is hypothesized to attenuate allergic asthma via inhibition of multiple signaling pathways. We used a comprehensive approach to elucidate the mechanism of action of artesunate by designing a novel biotinylated dihydroartemisinin (BDHA) to identify cellular protein targets of this anti-inflammatory drug. By adopting an untargeted proteomics approach, we demonstrated that artesunate may exert its protective anti-inflammatory effects via direct interaction with multiple proteins, most importantly with a number of mitochondrial enzymes related to glucose and energy metabolism, along with mRNA and gene expression, ribosomal regulation, stress responses, and structural proteins. In addition, the modulatory effects of artesunate on various cellular transcription factors were investigated using a transcription factor array, which revealed that artesunate can simultaneously modulate multiple nuclear transcription factors related to several major pro- and anti-inflammatory signaling cascades in human bronchial epithelial cells. Artesunate significantly enhanced nuclear levels of nuclear factor erythroid-2-related factor 2 (Nrf2), a key promoter of antioxidant mechanisms, which is inhibited by the Kelch-like ECH-associated protein 1 (Keap1). Our results demonstrate that, like other electrophilic Nrf2 regulators, artesunate activates this system via direct molecular interaction/modification of Keap1, freeing Nrf2 for transcriptional activity. Altogether, the molecular interactions and modulation of nuclear transcription factors provide invaluable insights into the broad pharmacological actions of artesunate in inflammatory lung diseases and related inflammatory disorders.

Deficiency of sorting nexin 10 prevents bone erosion in collagen-induced mouse arthritis through promoting NFATc1 degradation

Objective

Periarticular and subchondral bone erosion in rheumatoid arthritis caused by osteoclast differentiation and activation is a critical index for diagnosis, therapy and monitoring of the disease. Sorting nexin (SNX) 10, a member of the SNX family which functions in regulation of endosomal sorting, has been implicated to play an important clinical role in malignant osteopetrosis. Here we studied the roles and precise mechanisms of SNX10 in the bone destruction of collagen-induced arthritis (CIA) mice.

Methods

The role of SNX10 in bone destruction was evaluated by a CIA mice model which was induced in male SNX10−/− mice and wild type littermates. The mechanism was explored in osteoclasts induced by receptor activator of nuclear factor κB ligand from bone marrow mononuclear cells of wild type and SNX10−/− mice.

Results

SNX10 knockout prevented bone loss and joint destruction in CIA mice with reduced serum levels of TNF-α, interleukin 1β and anticollagen IgG 2α antibody. SNX10 deficiency did not block osteoclastogenesis, but significantly impaired osteoclast maturation and bone-resorption function by disturbing the formation of actin belt. The production of TRAP, CtsK and MMP9 in SNX10−/− osteoclasts was significantly inhibited, and partially restored by SNX10 overexpression. We further demonstrated that the degradation of NFATc1 was accelerated in SNX10−/− osteoclasts causing an inhibition of integrin β3-Src-PYK2 signalling.

Conclusions

Our study discloses a crucial role and novel mechanism for SNX10 in osteoclast function, and provides evidence for SNX10 as a promising novel therapeutic target for suppression of immune inflammation and bone erosion in rheumatoid arthritis.

Therapeutic effect of Cryptotanshinone on collagen-induced arthritis in rats via inhibiting nuclear factor kappa B signaling pathway

The discovery of new therapeutic drugs with the ability of preventing inflammation and joint destruction with less adverse effects is extremely urgent for rheumatoid arthritis (RA). Cryptotanshinone (CTS), an active component isolated from the root of Salvia miltiorrhiza Bunge, has been reported to have antibacterial and antitumor effects. However, its effects on RA have not been clearly elucidated. Here, we investigated the therapeutic effect of CTS on type II collagen-induced arthritis (CIA) in rats and explored the underlying mechanisms. Our results revealed that CTS treatment efficaciously ameliorated inflammation and joint destruction of rats with CIA. Both in vivo and in vitro studies showed that CTS suppressed the production of proinflammatory cytokines including interleukin 1β, tumor necrosis factor alpha, and interleukin 17α production and downregulated the production and activity of matrix metalloproteinase 9. By receptor activator of nuclear factor kappa B (NF-κB) ligand-induced bone marrow macrophages, we observed that CTS could inhibit osteoclast differentiation, which is critic for joint destruction. Further studies on inflammatory signaling revealed that CTS could inhibit the degradation of inhibitor of NF-κB (IκB) α in vivo and in vitro, prevent the nuclear translocation of NF-κB p65 induced by lipopolysaccharide in a time- and dose-dependent manner. By electrophoretic mobility shift assay and luciferase reporter assay, we found that CTS distinctively inhibited the NF-κB DNA binding activity and NF-κB-dependent luciferase activity. These results indicate that the therapeutic effect of CTS on CIA is accomplished mainly through the inhibition of NF-κB signaling. Our findings provide the evidence to develop CTS as a potential therapeutic agent for patients with RA.

Artesunate abolishes germinal center B cells and inhibits autoimmune arthritis

The antimalarial drug artemisinin and its derivatives exhibit potent immunosuppressive activity in several autoimmune disease models, however the mechanisms are not well-understood. This study was designed to investigate the therapeutic effects and the underlying mechanisms of the artemisinin analog artesunate using the K/BxN mouse model of rheumatoid arthritis. The well-studied disease mechanisms of K/BxN model allowed us to pinpoint the effect of artesunate on disease. Artesunate treatment prevented arthritis development in young K/BxN mice by inhibiting germinal center (GC) formation and production of autoantibodies. In adult K/BxN mice with established arthritis, artesunate diminished GC B cells in a few days. However, artesunate did not affect the follicular helper T cells (Tfh). In contrast to the spontaneous K/BxN model, artesunate treatment exerted minor influence on K/BxN serum transfer induced arthritis suggesting that artesunate has minimal effect on inflammatory responses downstream of antibody production. Finally, we showed that artesunate preferentially inhibits proliferating GC B cells. These results identify GC B cells as a target of artesunate and provide a new rationale for using artemisinin analogues to treat autoimmune diseases mediated by autoantibodies.

Subchronic toxicological study of two artemisinin derivatives in dogs

The objective of our study was to profile and compare the systematic changes between orally administered artesunate and intramuscularly injected artemether at a low dose over a 3-month period (92 consecutive days) in dogs. Intramuscular administration of 6 mg kg-1 artemether induced a decreased red blood cell (RBC) count (anemia), concurrent extramedullary hematopoiesis in the spleen and inhibition of erythropoiesis in the bone marrow. We also observed a prolonged QT interval and neuropathic changes in the central nervous system, which demonstrated the cortex and motor neuron vulnerability, but no behavioral changes. Following treatment with artesunate, we observed a decreased heart rate, which was most likely due to cardiac conduction system damage, as well as a deceased RBC count, extramedullary hematopoiesis in the spleen and inhibition of erythropoiesis in the bone marrow. However, in contrast to treatment with artemether, neurotoxicity was not observed following treatment with artesunate. In addition, ultra-structural examination by transmission electron microscopy showed mitochondrial damage following treatment with artesunate. These findings demonstrated the spectrum of toxic changes that result upon treatment with artesunate and artemether and show that the prolonged administration of low doses of these derivatives result in diverse toxicity profiles.

Effects of artesunate and ursolic acid on hyperlipidemia and its complications in rabbit

OBJECTIVE

To find the novel hypolipidemic agents, the effects of ursolic acid and artesunate on hyperlipidemia and its complications were determined in rabbit fed with Western-type diet.

METHODS AND RESULTS

New Zealand rabbits fed a Western-type diet developed a hyperlipidemia. Rabbits received ursolic acid (25mg/kg) or artesunate (25mg/kg) alone, or in combination (12.5+12.5mg/kg), to prevent hyperlipidemia. Ursolic acid or artesunate alone significantly decreased the plasma cholesterol and triglyceride in rabbits. Furthermore, they both attenuated liver steatosis and reduced the area of aortic root lesions. The combination of ursolic acid and artesunate was more potent than either agent alone, which indicates a strong synergistic effect.

CONCLUSION

The hypolipidemic effect of artesunate is firstly reported. Its combination with ursolic acid might have the potential to further develop for the treatment of atherosclerosis.

Further evidence for an anti-inflammatory role of artesunate in experimental cerebral malaria

BACKGROUND

Cerebral malaria (CM) is a clinical syndrome resulting from Plasmodium falciparum infection. A wide range of clinical manifestations follow the disease including cognitive dysfunction, seizures and coma. CM pathogenesis remains incompletely understood and without treatment this condition is invariably fatal. Artesunate has been accepted as the most effective drug for treating severe malaria. Besides its antiparasitic activity, an anti-inflammatory property has also been reported. In the current study, the immunomodulatory role of artesunate was investigated using a Plasmodium berghei ANKA model of CM, trough evaluation of behavioural changes and cytokines expression in hippocampus and in frontal cortex.

METHODS

C57Bl/6 mice were infected with P. berghei by intraperitoneal route, using a standardized inoculation of 106 parasitized erythrocytes. Memory function was evaluated using the step-down inhibitory avoidance test. The mRNA expression of IFN-γ, IL-1β, IL-6 and TNF in the frontal cortex and hippocampus of control and infected mice on day 5 post-infection were estimated by quantitative real time PCR. Plasmodium berghei -infected mice also received intraperitoneally a single dose of artesunate (32 mg/kg) on day 4 post-infection, and 24 hours after treatment behavioural and immunological analysis were performed. The protein levels of cytokines IL-2, IL-6, IL-10, IL-17, IFN-γ, TNF in the serum, frontal cortex and hippocampus of controls and P. berghei -infected mice treated or not treated with artesunate were determined using a cytometric bead array (CBA) kit. The survival and neurological symptoms of CM were also registered.

RESULTS

CM mice presented a significant impairment of aversive memory compared to controls on day 5 post-infection. A higher mRNA expression of pro-inflammatory cytokines was found in the hippocampus and frontal cortex of infected mice. A single dose of artesunate was also able to decrease the expression of inflammatory cytokines in the hippocampus and frontal cortex of P. berghei-infected mice. In parallel, a significant improvement in neurological symptoms and survival were observed in artesunate treated mice.

CONCLUSIONS

In summary, the current study provided further evidence that CM affects key brain areas related to cognition process. In addition, different patterns of cytokine expression during the course of CM could be modulated by a single administration of the anti-malarial artesunate.