Celastrus aculeatus Merr. suppresses the induction and progression of autoimmune arthritis by modulating immune response to heat-shock protein 65

Natural Product-Derived Phytochemicals for Influenza A Virus (H1N1) Prevention and Treatment

Influenza A (H1N1) viruses are prone to antigenic mutations and are more variable than other influenza viruses. Therefore, they have caused continuous harm to human public health since the pandemic in 2009 and in recent times. Influenza A (H1N1) can be prevented and treated in various ways, such as direct inhibition of the virus and regulation of human immunity. Among antiviral drugs, the use of natural products in treating influenza has a long history, and natural medicine has been widely considered the focus of development programs for new, safe anti-influenza drugs. In this paper, we focus on influenza A (H1N1) and summarize the natural product-derived phytochemicals for influenza A virus (H1N1) prevention and treatment, including marine natural products, flavonoids, alkaloids, terpenoids and their derivatives, phenols and their derivatives, polysaccharides, and derivatives of natural products for prevention and treatment of influenza A (H1N1) virus. We further discuss the toxicity and antiviral mechanism against influenza A (H1N1) as well as the druggability of natural products. We hope that this review will facilitate the study of the role of natural products against influenza A (H1N1) activity and provide a promising alternative for further anti-influenza A drug development.

Toxic metabolites and metabolic soft spots of celastrol based on glutathione metabolic capture and high-resolution mass spectrometry

BACKGROUND

Celastrol is known as one of the most medicinally valuable compounds. However, the pharmaceutical application of celastrol is significantly limited due to high toxicity, while there are few reports on the mechanism of toxicity.

METHODS

This study searched for possible toxic metabolites through phase I in vitro metabolism and glutathione capture experiments. Then in vivo metabolism experiments in mice and rats were conducted to look for metabolites in vivo. Finally, mice in vivo toxicity experiment was conducted to verify the toxicity of different doses of celastrol to mice.

RESULTS

In the in vivo and in vitro metabolism experiments, we found 7 phase I metabolites in vitro, 9 glutathione conjugation metabolites in vitro, and 20 metabolites in vivo. The metabolic soft points of celastrol could be the quinone methyl structure at C3-OH and C6. In vivo toxicity experiments show that celastrol causes weight loss, diarrhea, gastrointestinal tract and liver inflammation in mice.

CONCLUSIONS

This study analyzed the metabolites and possible metabolic soft spots of celastrol, and its hepatotoxicity and gastrointestinal toxicity were demonstrated through in vivo studies for the first time. The results might provide an important basis for potential structural modification to increase the druggability of celastrol.

Prevention and Treatment of Osteoporosis Using Chinese Medicinal Plants: Special Emphasis on Mechanisms of Immune Modulation

Numerous studies have examined the pathogenesis of osteoporosis. The causes of osteoporosis include endocrine factors, nutritional status, genetic factors, physical factors, and immune factors. Recent osteoimmunology studies demonstrated that the immune system and immune factors play important regulatory roles in the occurrence of osteoporosis, and people should pay more attention to the relationship between immunity and osteoporosis. Immune and bone cells are located in the bone marrow and share numerous regulatory molecules, signaling molecules, and transcription factors. Abnormal activation of the immune system alters the balance between osteoblasts and osteoclasts, which results in an imbalance of bone remodeling and osteoporosis. The incidence of osteoporosis is also increasing with the aging of China's population, and traditional Chinese medicine has played a vital role in the prevention and treatment of osteoporosis for centuries. Chinese medicinal plants possess unique advantages in the regulation of the immune system and the relationships between osteoporosis and the immune system. In this review, we provide a general overview of Chinese medicinal plants in the prevention and treatment of osteoporosis, focusing on immunological aspects.

Celastrol and Its Role in Controlling Chronic Diseases

Celastrol, a triterpenoid derived from traditional Chinese medicinal plants, has anti-inflammatory, antioxidant, and anticancer activities. Celastrol has shown preventive/therapeutic effects in experimental models of several chronic diseases. These include, chronic inflammatory and autoimmune diseases (e.g., rheumatoid arthritis, multiple sclerosis, systemic lupus erythematosus, inflammatory bowel disease, and psoriasis), neurodegenerative disorders (e.g., Alzheimer's disease, Parkinson's disease, and Amyotrophic lateral sclerosis), atherosclerosis, obesity, Type 2 diabetes, and cancer. Celastrol modulates intricate cellular pathways and networks associated with disease pathology, and it interrupts or redirects the aberrant cellular and molecular events so as to limit disease progression and facilitate recovery, where feasible. The major cell signaling pathways modulated by celastrol include the NF-kB pathway, MAPK pathway, JAK/STAT pathway, PI3K/Akt/mTOR pathway, and antioxidant defense mechanisms. Furthermore, celastrol modulates cell proliferation, apoptosis, proteasome activity, heat-shock protein response, innate and adaptive immune responses, angiogenesis, and bone remodeling. Current understanding of the mechanisms of action of celastrol and information about its disease-modulating activities in experimental models have set the stage for testing celastrol in clinical studies as a therapeutic agent for several chronic human diseases.

Pristimerin inhibits angiogenesis in adjuvant-induced arthritic rats by suppressing VEGFR2 signaling pathways

Rheumatoid arthritis (RA) is a progressive, inflammatory autoimmune disease. As RA progresses, the hyperplastic synovial pannus creates a hypoxic, inflammatory environment that induces angiogenesis. Further vascularization of the synovial tissue promotes pannus growth and continued infiltration of inflammatory leukocytes, thus perpetuating the disease. Pristimerin inhibits inflammation and tumor angiogenesis. The present study focused on the inhibition of angiogenesis by Pristimerin in adjuvant-induced arthritic rats and the underlying molecular mechanisms. Our results clearly demonstrate for the first time that Pristimerin significantly reduces vessel density in synovial membrane tissues of inflamed joints and reduces the expression of pro-angiogenic factors in sera, including TNF-α, Ang-1, and MMP-9. Pristimerin also decreased the expression of VEGF and p-VEGFR2 in the synovial membrane, whereas the total amount of VEGFR2 remained unchanged. Pristimerin suppressed the sprouting vessels of the aortic ring and inhibited VEGF-induced HFLS-RA migration in vitro. Pristimerin also inhibited VEGF-induced proliferation, migration and tube formation by HUVECs, blocked the autophosphorylation of VEGF-induced VEGFR2 and consequently downregulated the signaling pathways of activated PI3K, AKT, mTOR, ERK1/2, JNK, and p38 in VEGF-induced HUVECs. Our results indicate that Pristimerin suppressed synovial angiogenesis in our rat model and in vitro by interrupting the targeting of VEGFR2 activation. Therefore, Pristimerin has potential as an angiogenesis inhibitor in the treatment of rheumatoid arthritis.

Celastrol, a Chinese herbal compound, controls autoimmune inflammation by altering the balance of pathogenic and regulatory T cells in the target organ

Inflammation is an integral component of autoimmune arthritis. The balance of pathogenic T helper 17 (Th17) and protective T regulatory (Treg) cells can influence disease severity, and its resetting offers an attractive approach to control autoimmunity. We determined the frequency of Th17 and Treg in the joints of rats with adjuvant arthritis (AA), a model of rheumatoid arthritis (RA). We also investigated the impact of Celastrol, a bioactive compound from the traditional Chinese medicine Celastrus that can suppress AA, on Th17/Treg balance in the joints. Celastrol treatment reduced Th17 cells but increased Treg in the joints, and it inhibited Th17 differentiation but promoted Treg differentiation in vitro by blocking the activation of pSTAT3. Furthermore, Celastrol limited the production of Th17-differentiating cytokines and chemokines (CCL3, CCL5). Thus, Celastrol suppressed arthritis in part by altering Th17/Treg ratio in inflamed joints, and it should be tested as a potential adjunct/alternative for RA therapy.

Ethyl Acetate Extract from Celastrus aculeatus Merr. Suppresses Synovial Inflammation in Adjuvant Arthritis Rats through Apoptosis Induction of CD4(+)CD25(+)FOXP3(+) T Cells

Celastrus aculeatus Merr. has been widely used in traditional Chinese medicine to treat rheumatoid arthritis (RA) in clinic. However, the main active fraction of this plant is still unclear. In this study, we attempted to evaluate the suppressive effect of ethyl acetate extract (EAE) from Celastrus aculeatus Merr. on synovial inflammation in adjuvant arthritis (AA) rats induced by Mycobacterium tuberculosis H37Ra (Mtb) and to explore the underlying mechanisms. SD rats immunized with heat-killed Mtb were fed with EAE and observed for erythema, swelling, and induration of each paw. The pathologic changes in joint synovium were tested by hematoxylin-eosin staining. Apoptosis induction of synoviocytes was tested immunohistochemically. Apoptosis of peripheral lymphocytes and the level of regulatory T cells were analyzed by flow cytometry. After treatment with EAE, the joint inflammation in rats with AA was alleviated. Both apoptotic ratios of synoviocytes and peripheral lymphocytes and the ratio of CD4⁺CD25⁺FOXP3⁺ to CD4 regulatory T cells were significantly increased. In summary, we first demonstrated that EAE of Celastrus aculeatus Merr. can inhibit synovial inflammation in AA rats through apoptosis induction of CD4⁺CD25⁺FOXP3⁺ T cells. Our study provides a rationale for the application of Celastrus aculeatus Merr. to treat RA.

Pristimerin, a naturally occurring triterpenoid, protects against autoimmune arthritis by modulating the cellular and soluble immune mediators of inflammation and tissue damage

Rheumatoid arthritis (RA) is a chronic autoimmune disorder affecting the synovial joints. The currently available drugs for RA are effective only in a proportion of patients and their prolonged use is associated with severe adverse effects. Thus, new anti-arthritic agents are being sought. We tested Pristimerin, a naturally occurring triterpenoid, for its therapeutic activity against rat adjuvant arthritis. Pristimerin effectively inhibited both arthritic inflammation and cartilage and bone damage in the joints. Pristimerin-treated rats exhibited a reduction in the pro-inflammatory cytokines (IL-6, IL-17, IL-18, and IL-23) and the IL-6/IL-17-associated transcription factors (pSTAT3 and ROR-γt), coupled with an increase in the immunomodulatory cytokine IL-10. Also increased was IFN-γ, which can inhibit IL-17 response. In addition, the Th17/Treg ratio was altered in favor of immune suppression and the RANKL/OPG ratio was skewed towards anti-osteoclastogenesis. This is the first report on testing Pristimerin in arthritis. We suggest further evaluation of Pristimerin in RA patients.

Anti-invasive effects of Celastrus Orbiculatus extract on interleukin-1 beta and tumour necrosis factor-alpha combination-stimulated fibroblast-like synoviocytes

Background

Invasion of fibroblast-like synoviocytes (FLSs) is critical in the pathogenesis of rheumatoid arthritis (RA). The metalloproteinases (MMPs) and activator of nuclear factor-kappa B (NF-κB) pathway play a critical role in RA-FLS invasion induced by interleukin-1 beta (IL-1β) and tumour necrosis factor-alpha (TNF-α). The present study aimed to explore the anti-invasive activity and mechanism of Celastrus orbiculatus extract (COE) on IL-1β and TNF-α combination-stimulated human RA-FLSs.

Methods

We investigated the effect of COE on IL-1β and TNF-α combination-induced FLS invasion as well as MMP expression and explored upstream signal transduction.

Results

COE suppressed IL-1β and TNF-α combination-stimulated FLSs invasion by inhibiting MMP-9 expression and activity. Furthermore, our results revealed that COE inhibited the transcriptional activity of MMP-9 by suppression of the binding activity of NF-κB in the MMP-9 promoter, and inhibited IκBα phosphorylation and nuclear translocation of NF-κB.

Conclusions

COE inhibits IL-1β and TNF-α combination-induced FLSs invasion by suppressing NF-κB-mediated MMP-9 expression.

Temporal cytokine expression and the target organ attributes unravel novel aspects of autoimmune arthritis

Susceptibility to autoimmunity is determined by multiple factors. Defining the contribution of the quantitative versus qualitative aspects of antigen-directed immune responses as well as the factors influencing target organ susceptibility is vital to advancing the understanding of the pathogenesis of autoimmunity. In a series of studies, we have addressed these issues using the adjuvant-induced arthritis (AA) model of human rheumatoid arthritis (RA). Lewis rats are susceptible to AA following immunization with heat-killed Mycobacterium tuberculosis H37Ra, whereas Wistar-Kyoto (WKY) rats of the same MHC (major histocompatibility complex) haplotype are resistant. Comparative studies on these and other susceptible/resistant rodent strains have offered interesting insights into differential cytokine responses in the face of comparable T cell proliferative response to the disease relevant antigens. Study of the cytokine kinetics have also permitted validation of the disease-protective versus disease-aggravating effects of specific cytokines by treatment of rats/mice with those cytokines at different phases of the disease. In regard to the target organ attributes, the migration of arthritogenic leukocytes into the joints; the expression of mediators of inflammation, angiogenesis, and tissue damage; the role of vascular permeability; and the characteristics of vascular endothelial cells have been examined. Further, various inhibitors of angiogenesis are effective in suppressing arthritis. Taken together, the differential cytokine responses and unique attributes of the target organ have revealed novel aspects of disease susceptibility and joint damage in AA. The translation of this basic research in animal models to RA patients would not only advance our understanding of the disease process, but also offer novel avenues for immunomodulation of this disease.

Anti-invasive effects of celastrol in hypoxia-induced fibroblast-like synoviocyte through suppressing of HIF-1α/CXCR4 signaling pathway

Rheumatoid arthritis (RA) joints are in a hypoxic condition. Hypoxia-induced migration and invasion of fibroblast-like synoviocytes (FLSs) are considered to play a critical role in the pathogenesis of RA. Among the key genes upregulated by hypoxia-inducible factor-1α (HIF-1α), CXC chemokine receptor 4 (CXCR4) plays an important role in FLS migration and invasion. Our previous studies have shown that celastrol exerts anti-arthritic effects by inhibiting FLS migration and invasion under normoxic conditions. However, the effect and molecular mechanisms underlying the effect of celastrol on hypoxia-induced FLS migration and invasion are poorly understood. In the present study, we assessed the effect of celastrol on hypoxia-induced FLS migration and invasion. Results showed that celastrol suppressed hypoxia-induced FLS migration and invasion. In addition, we also found that celastrol inhibited hypoxia-induced CXCR4 expression at both the mRNA and the protein levels in RA-FLSs. Meanwhile, it is revealed that celastrol inhibited the transcriptional activity of CXCR4 under hypoxic conditions by suppressing the binding activity of HIF-1α in the CXCR4 promoter, and blocked hypoxia-induced accumulation of nuclear HIF-1α. Furthermore, treatment with HIF-1α inhibitor reduced the hypoxia-induced expression and transcriptional activity of CXCR4. In conclusion, our results indicate that celastrol inhibits hypoxia-induced migration and invasion via suppression of HIF-1α mediated CXCR4 expression in FLSs under hypoxic conditions. These results provide a strong rationale for further testing and validation of the use of celastrol as a new alternative for using in the treatment of RA.

Sinomenine suppresses osteoclast formation and Mycobacterium tuberculosis H37Ra-induced bone loss by modulating RANKL signaling pathways

Receptor activator of NF-κB ligand (RANKL) is essential for osteoclastogenesis. Targeting RANKL signaling pathways has been an encouraging strategy for treating lytic bone diseases such as osteoporosis and rheumatoid arthritis (RA). Sinomenine (SIN), derived from Chinese medicinal plant Sinomenioumacutum, is an active compound to treat RA, but its effect on osteoclasts has been hitherto unknown. In the present study, SIN was found to ameliorate M. tuberculosis H37Ra (Mt)-induced bone loss in rats with a decreased serum level of TRACP5b and RANKL, and an increased level of osteoprotegerin (OPG). In vitro study also showed that SIN could inhibit RANKL-induced osteoclast formation and bone resorption. The osteoclastic specific marker genes induced by RANKL including c-Src, MMP-9, TRACP were inhibited by SIN in a dose dependent manner. Signal transduction studies showed that SIN could obviously reduce the expression of RANK adaptor molecule TRAF6 and down-regulate RANKL-induced NF-κB activation. It decreased the RANKL-induced p38, JNK posphorylation but not ERK1/2 posphorylation. SIN could also reduce RANKL-mediated calcium influx which is associated with TRAF6/c-Src complex. Finally, SIN suppressed RANKL induced AP-1 and NFAT transcription, as well as the gene expression of NFATc1 and AP-1 components (Fra-1, Fra-2, c-Fos). The protein expression of c-Fos and TRAF6 were also inhibited by SIN after RANKL stimulation. Taken together, SIN could attenuate osteoclast formation and Mt-induced bone loss by mediating RANKL signaling pathways.

Promising effects on ameliorating mitochondrial function and enhancing Akt signaling in SH-SY5Y cells by (M)-bicelaphanol A, a novel dimeric podocarpane type trinorditerpene isolated from Celastrus orbiculatus

Oxidative stress plays an important role in the pathological processes of various neurodegenerative diseases. In this study, we investigated the neuroprotective effects of (M)-bicelaphanol A, which has been the first dimeric podocarpane type trinorditerpene isolated from Celastrus orbiculatus, against hydrogen peroxide (H2O2)-induced injury in human SH-SY5Y neuroblastoma cells. Our study showed that cells pretreated with (M)-bicelaphanol A significantly attenuated H2O2-induced cell viability reduction and cell apoptosis. These neuroprotective effects of (M)-bicelaphanol A were associated with a reduction of reactive oxygen species and an increase in the level of adenosine triphosphate. In addition, (M)-bicelaphanol A pretreatment markedly increased the phosphorylation level of Akt in SH-SY5Y cells. In conclusion, our results for the first time demonstrate that the protection of (M)-bicelaphanol A on SH-SY5Y cells against H2O2-induced oxidative stress may attribute, at least partially, to its attenuation of mitochondrial dysfunction and activation of Akt signaling pathway. Above results shed more light on the molecular mechanisms involved in the neuroprotective effects of (M)-bicelaphanol A, which could be a potential drug candidate for the treatment of oxidative stress-associated neurodegenerative diseases.

Celastrol inhibits lipopolysaccharide-stimulated rheumatoid fibroblast-like synoviocyte invasion through suppression of TLR4/NF-κB-mediated matrix metalloproteinase-9 expression

Invasion of fibroblast-like synoviocytes (FLSs) is critical in the pathogenesis of rheumatoid arthritis (RA). The metalloproteinases (MMPs) and activator of Toll-like receptor 4 (TLR4)/nuclear factor-κB (NF-κB) pathway play a critical role in RA-FLS invasion induced by lipopolysaccharide (LPS). The present study aimed to explore the anti-invasive activity of celastrol on LPS-stimulated human RA-FLSs, and to elucidate the mechanism involved. We investigated the effect of celastrol on LPS-induced FLS migration and invasion as well as MMP expression and explored the upstream signal transduction. Results showed that celastrol suppressed LPS-stimulated FLS migration and invasion by inhibiting MMP-9 expression and activity. Furthermore, our results revealed that celastrol inhibited the transcriptional activity of MMP-9 by suppressing the binding activity of NF-κB in the MMP-9 promoter, and suppressed the TLR4/MyD88/NF-κB pathway. Administration of celastrol (0.5 mg/kg and 1 mg/kg, intraperitoneally) daily for 3 weeks in a collagen-induced arthritis rat model markedly alleviated the clinical signs, synovial hyperplasia and inflammatory cell infiltration of joints. In conclusion, celastrol might inhibit FLS migration and invasion induced by LPS by suppressing TLR4/NF-κB-mediated MMP-9 expression, providing a theoretical foundation for the clinical treatment of RA with celastrol.

Microarray-based gene expression profiling reveals the mediators and pathways involved in the anti-arthritic activity of Celastrus-derived Celastrol

Rheumatoid arthritis (RA) is an autoimmune disease characterized by chronic inflammation of the joints. The prolonged use of non-steroidal anti-inflammatory drugs and other newer drugs is associated with severe adverse reactions. Therefore, there is a need for newer anti-arthritic agents. Celastrol, a bioactive component of the Chinese herb Celastrus, possesses anti-arthritic activity as tested in the adjuvant arthritis (AA) model of rheumatoid arthritis (RA). However, the mechanism of action of Celastrol has not been fully defined. We reasoned that microarray analysis of the lymphoid cells of Celastrol-treated arthritic animals might provide vital clues in this regard. We isolated total RNA of the draining lymph node cells (LNCs) of Celastrol-treated (Tc) and vehicle-treated (Tp) arthritic Lewis rats that were restimulated in vitro with the disease-related antigen, mycobacterial heat-shock protein 65 (Bhsp65), and tested it using microarray gene chips. Also tested was RNA from LNCs of control arthritic rats just before any treatment (T₀). Seventy six genes involved in various biological functions were differentially regulated by Bhsp65 in LNCs of Tp group, and 19 genes among them were shared by the Tc group. Furthermore, a group of 14 genes was unique to Tc. When Tc and Tp were compared, many of the Bhsp65-induced genes were related to the immune cells, cellular proliferation and inflammatory responses. Our results revealed 10 differentially expressed genes and 14 pathways that constituted the "Celastrol Signature". Our results would help identify novel targets for RA therapy.

Celastrus treatment modulates antigen-induced gene expression in lymphoid cells of arthritic rats

Rheumatoid arthritis (RA) is a debilitating autoimmune disease of global prevalence and the disease process primarily targets the synovial joints. Despite improvements in the treatment of RA over the past decade, there still is a need for new therapeutic agents that are efficacious, less expensive, and free of severe adverse reactions. Celastrus has been used in China for centuries for the treatment of rheumatic diseases. Furthermore, we previously reported that ethanol extract of Celastrus aculeatus Merr. (Celastrus) attenuates adjuvant-induced arthritis (AA) in rats. However, the mechanisms underlying the anti-arthritic activity of Celastrus have not yet been fully defined. We reasoned that microarray analysis might offer useful insights into the pathways and molecules targeted by Celastrus. We compared the gene expression profiles of the draining lymph node cells (LNC) of Celastrus-treated (Tc) versus water-treated (Tw) rats, and each group with untreated arthritic rats (T(0)). LNC were restimulated with mycobacterial heat shock protein-65 (Bhsp65). We identified 104 differentially expressed genes (DEG) (8 upregulated, 96 downregulated) when comparing Tc with T(0) rats, in contrast to 28 (12 upregulated, 16 downregulated) when comparing Tw and T(0) rats. Further, 20 genes (6 upregulated, 14 downregulated) were shared by both Tw and Tc groups. Thus, Celastrus treatment (Tc) significantly downregulated a large proportion of genes compared to controls (Tw). The DEG were mainly associated with the processes of immune response, cell proliferation and apoptosis, and cell signaling. These results provide novel insights into the mechanism of Celastrus anti-arthritic activity, and unravel potential therapeutic targets for arthritis.

Suppression of autoimmune arthritis by Celastrus-derived Celastrol through modulation of pro-inflammatory chemokines

Rheumatoid arthritis (RA) is an autoimmune disease characterized by chronic inflammation of the synovial joints, deformities, and disability. The prolonged use of conventional anti-inflammatory drugs is associated with severe adverse effects. Therefore, there is an urgent need for safer and less expensive therapeutic products. Celastrol is a bioactive component of Celastrus, a traditional Chinese medicine, and it possesses anti-arthritic activity. However, the mechanism of action of Celastrol remains to be fully defined. In this study based on the rat adjuvant-induced arthritis (AA) model of RA, we examined the effect of Celastrol on two of the key mediators of arthritic inflammation, namely chemokines and their receptors, and related pro-inflammatory cytokines. We treated arthritic Lewis rats with Celastrol (200μg/rat) or its vehicle by daily intraperitoneal (ip) injection beginning at the onset of AA. At the peak phase of AA, the sera, the draining lymph node cells, spleen adherent cells, and synovial-infiltrating cells of these rats were harvested and tested. Celastrol-treated rats showed a significant reduction in the levels of chemokines (RANTES, MCP-1, MIP-1α, and GRO/KC) as well as cytokines (TNF-α and IL-1β) that induce them, compared to the vehicle-treated rats. However, Celastrol did not have much effect on cellular expression of chemokine receptors except for an increase in CCR1. Further, Celastrol inhibited the migration of spleen adherent cells in vitro. Thus, Celastrol-induced suppression of various chemokines that mediate cellular infiltration into the joints might contribute to its anti-arthritic activity. Our results suggest that Celastrol might offer a promising alternative/adjunct treatment for RA.

Developing Phytocompounds from Medicinal Plants as Immunomodulators

Imbalance or malfunction of the immune systems is associated with a range of chronic diseases including autoimmune diseases, allergies, cancers and others. Various innate and adaptive immune cells that are integrated in this complex networking system may represent promising targets for developing immunotherapeutics for treating specific immune diseases. A spectrum of phytochemicals have been isolated, characterized and modified for development and use as prevention or treatment of human diseases. Many cytotoxic drugs and antibiotics have been developed from phytocompounds, but the application of traditional or new medicinal plants for use as immunomodulators in treating immune diseases is still relatively limited. In this review, a selected group of medicinal herbs, their derived crude or fractionated phytoextracts and the specific phytochemicals/phytocompounds isolated from them, as well as categorized phytocompound groups with specific chemical structures are discussed in terms of their immunomodulatory bioactivities. We also assess their potential for future development as immunomodulatory or inflammation-regulatory therapeutics or agents. New experimental approaches for evaluating the immunomodulatory activities of candidate phytomedicines are also discussed.

Celastrus and its bioactive celastrol protect against bone damage in autoimmune arthritis by modulating osteoimmune cross-talk

Rheumatoid arthritis (RA) is a chronic inflammatory disease characterized by bone erosion and cartilage destruction in the joints. Many of the conventional antiarthritic drugs are effective in suppressing inflammation, but they do not offer protection against bone damage. Furthermore, the prolonged use of these drugs is associated with severe adverse reactions. Thus, new therapeutic agents that can control both inflammation and bone damage but with minimal side effects are sought. Celastrus is a Chinese herb that has been used for centuries in folk medicine for the treatment of various inflammatory diseases. However, its utility for protection against inflammation-induced bone damage in arthritis and the mechanisms involved therein have not been examined. We tested celastrus and its bioactive component celastrol for this attribute in the adjuvant-induced arthritis model of RA. The treatment of arthritic rats with celastrus/celastrol suppressed inflammatory arthritis and reduced bone and cartilage damage in the joints as demonstrated by histology and bone histomorphometry. The protective effects against bone damage are mediated primarily via the inhibition of defined mediators of osteoclastic bone remodeling (e.g. receptor activator of nuclear factor-κB ligand (RANKL)), the deviation of RANKL/osteoprotegerin ratio in favor of antiosteoclastic activity, and the reduction in osteoclast numbers. Furthermore, both the upstream inducers (proinflammatory cytokines) and the downstream effectors (MMP-9) of the osteoclastogenic mediators were altered. Thus, celastrus and celastrol controlled inflammation-induced bone damage by modulating the osteoimmune cross-talk. These natural products deserve further consideration and evaluation as adjuncts to conventional therapy for RA.

Nicotine-induced differential modulation of autoimmune arthritis in the Lewis rat involves changes in interleukin-17 and anti-cyclic citrullinated peptide antibodies

OBJECTIVE

Rheumatoid arthritis (RA) is a debilitating autoimmune disease, and smoking is an important environmental factor in a subset of RA patients. A role of the cholinergic antiinflammatory pathway in autoimmune inflammation is increasingly being realized. Nicotine is a major component of cigarette smoke, and it stimulates the α7 nicotinic acetylcholine receptors. Therefore, defining the mechanisms underlying the immunomodulatory effects of nicotine on arthritis is of high relevance. The purpose of this study was to address this issue using the rat adjuvant-induced arthritis (AIA) model of human RA.

METHODS

Lewis rats were immunized subcutaneously with heat-killed Mycobacterium tuberculosis H37Ra for disease induction. Rats were treated with nicotine intraperitoneally either before (pretreatment) or after (posttreatment) the onset of AIA. Control rats received the vehicle (buffer) in place of nicotine. The severity of arthritis was assessed and graded. The draining lymph node cells were tested for T cell proliferative and cytokine responses against the disease-related antigen mycobacterial heat-shock protein 65. The sera were tested for anti-cyclic citrullinated peptide (anti-CCP) antibodies and anti-mycobacterial Hsp65 antibodies.

RESULTS

Nicotine pretreatment aggravated the arthritis, whereas nicotine posttreatment suppressed the disease. This altered severity of AIA directly correlated with the levels of the anti-CCP antibodies, of the Th1/Th17 cytokines, and of the corresponding dendritic cell-derived cytokines. The majority of these effects on cellular responses could be replicated in vitro.

CONCLUSION

Nicotine-induced modulation of AIA involves specific alterations in the disease-related cellular and humoral immune responses in AIA. These results are of significance in advancing our understanding of the pathogenesis of RA.

Topical dermal application of essential oils attenuates the severity of adjuvant arthritis in Lewis rats

This study was aimed at examining the effect of an ointment containing essential oils (EO) on the severity of adjuvant arthritis (AA), an experimental model of human rheumatoid arthritis (RA), in Lewis rats and to define the underlying mechanisms. At the onset of AA, the rats received topical application twice daily of an ointment containing 20% EO or placebo ointment. The synovial fluid (SF) and synovium-infiltrating cells (SIC) of rats were tested for pro-inflammatory cytokines TNF-α and IL-1β. The hind paws and skin were examined histologically. The activity/level of matrix metalloproteinases (MMPs) and anti-mycobacterial heat-shock protein 65 (Bhsp65) antibodies were tested. Arthritic rats treated with ointment containing EO developed less severe clinical arthritis compared with the controls, and this activity was attributable to EO and not to the carrier oil. The levels of TNF-α and IL-1β, and the activity of MMPs in SF and SIC-lysate were significantly reduced in EO-treated arthritic rats compared with the controls. However, the levels of anti-Bhsp65 antibodies were unaffected by treatment. Thus, topical dermal delivery of EO-containing ointment down-modulates the severity of AA in Lewis rats by inhibiting defined mediators of inflammation. Such ointments should be tested in patients with RA and other arthritic conditions.

Anti-inflammatory and anti-nociceptive effect of Betula platyphylla var. japonica in human interleukin-1β-stimulated fibroblast-like synoviocytes and in experimental animal models

ETHNOPHARMACOLOGICAL RELEVANCE

Traditional medicine has widely been used Betula platyphylla var. japonica to treat various inflammatory diseases including arthritis.

AIM OF THE STUDY

To determine the anti-inflammatory, anti-nociceptive, and anti-arthritic effects of Betula platyphylla in interleukin-1β (IL-1β)-stimulated fibroblast-like synoviocytes from human rheumatoid arthritis and in nociceptive and inflammatory animal model.

MATERIALS AND METHODS

The inflammatory mediators such as IL-6, tumor necrosis factor (TNF)-α matrix metalloproteinase (MMP)-1, MMP-13, inducible nitric oxide synthesis (iNOS), nitrites, prostaglandin E(2) (PGE(2)) and cyclo-oxygenase 2 (COX-2) activity of Betula platyphylla were tested in IL-1β-stimulated fibroblast-like synoviocytes. Tail withdrawal in response to thermal stimulation in tail flick test or paw flinching and shaking in response to sc hind paw formalin injection was measured 1h after oral administration of Betula platyphylla. The former was evaluated with a paw pressure test, and the latter was measured using the squeaking score, and paw volume in inflammatory arthritis tests.

RESULTS

Betula platyphylla significantly inhibited proliferation of IL-1β-induced synoviocytes. Betula platyphylla reduced the levels of inflammatory mediators, such as IL-6, TNF-α, MMP-1, MMP13, and PGE(2). In particular, Betula platyphylla significantly inhibited the releases of nitrites and iNOS, as well as release of NFκB, into the nucleus of IL-1β-treated synoviocytes, even at concentrations as low as 1μg/ml. Oral administrant of Betula platyphylla at 400mg/kg significantly decreased about 27.8% of tail flick withdrawal and inhibited about the number of paw flinches in both phases 1 and 2 of the formalin test. In the carrageenan-induced acute pain and arthritis model, Betula platyphylla dose dependently reduced the nociceptive threshold and the arthritic symptoms at day 8, respectively, and Betula platyphylla at 400mg/kg markedly reduced the inflammatory area about 48% in the ankle joints. This capacity of Betula platyphylla at 400mg/kg was similar to that of the celecoxib-2 inhibitor in carrageenan-induced nociceptive and inflammatory arthritis model.

CONCLUSIONS

These results suggest that Betula platyphylla has anti-nociceptive and anti-inflammatory effects in IL-1β-stimulated RA FLS and in an animal model of arthritis. Thus, the use of Betula platyphylla as a pharmaceutical candidate for the treatment of arthritis should be further studied.

Celastrus-derived celastrol suppresses autoimmune arthritis by modulating antigen-induced cellular and humoral effector responses

Rheumatoid arthritis (RA) is an autoimmune disease characterized by synovial inflammation and articular damage. Proinflammatory cytokines, antibodies, and matrix-degrading enzymes orchestrate the pathogenic events in autoimmune arthritis. Accordingly, these mediators of inflammation are the targets of several anti-arthritic drugs. However, the prolonged use of such drugs is associated with severe adverse reactions. This limitation has necessitated the search for less toxic natural plant products that possess anti-arthritic activity. Furthermore, it is imperative that the mechanism of action of such products be explored before they can be recommended for further preclinical testing. Using the rat adjuvant-induced arthritis model of human RA, we demonstrate that celastrol derived from Celastrus has potent anti-arthritic activity. This suppression of arthritis is mediated via modulation of the key proinflammatory cytokines (IL-17, IL-6, and IFN-γ) in response to the disease-related antigens, of the IL-6/IL-17-related transcription factor STAT3, of antibodies directed against cyclic citrullinated peptides and Bhsp65, and of the activity of matrix metalloproteinase-9 and phospho-ERK. Most of the clinical and mechanistic attributes of celastrol are similar to those of Celastrus extract. Several studies have addressed the antitumor activity of celastrol. Our study highlights the anti-arthritic activity of Celastrus-derived celastrol and the underlying mechanisms. These results provide a strong rationale for further testing and validation of the use of celastrol and the natural plant extract from Celastrus as an adjunct (with conventional drugs) or alternative modality for the treatment of RA.

Herbal medicinal products target defined biochemical and molecular mediators of inflammatory autoimmune arthritis

Rheumatoid arthritis (RA) is a chronic debilitating disease characterized by synovial inflammation, damage to cartilage and bone, and deformities of the joints. Several drugs possessing anti-inflammatory and immunomodulatory properties are being used in the conventional (allopathic) system of medicine to treat RA. However, the long-term use of these drugs is associated with harmful side effects. Therefore, newer drugs with low or no toxicity for the treatment of RA are actively being sought. Interestingly, several herbs demonstrate anti-inflammatory and anti-arthritic activity. In this review, we describe the role of the major biochemical and molecular mediators in the pathogenesis of RA, and highlight the sites of action of herbal medicinal products that have anti-arthritic activity. With the rapidly increasing use of CAM products by patients with RA and other inflammation-related disorders, our review presents timely information validating the scientific rationale for the use of natural therapeutic products.

Immunomodulation of Autoimmune Arthritis by Herbal CAM

Rheumatoid arthritis (RA) is a debilitating autoimmune disease of global prevalence. The disease is characterized by synovial inflammation leading to cartilage and bone damage. Most of the conventional drugs used for the treatment of RA have severe adverse reactions and are quite expensive. Over the years, increasing proportion of patients with RA and other immune disorders are resorting to complementary and alternative medicine (CAM) for their health needs. Natural plant products comprise one of the most popular CAM for inflammatory and immune disorders. These herbal CAM belong to diverse traditional systems of medicine, including traditional Chinese medicine, Kampo, and Ayurvedic medicine. In this paper, we have outlined the major immunological pathways involved in the induction and regulation of autoimmune arthritis and described various herbal CAM that can effectively modulate these immune pathways. Most of the information about the mechanisms of action of herbal products in the experimental models of RA is relevant to arthritis patients as well. The study of immunological pathways coupled with the emerging application of genomics and proteomics in CAM research is likely to provide novel insights into the mechanisms of action of different CAM modalities.

Suppression of ongoing experimental arthritis by a chinese herbal formula (huo-luo-xiao-ling dan) involves changes in antigen-induced immunological and biochemical mediators of inflammation

Rheumatoid arthritis (RA) is one of the major autoimmune diseases of global prevalence. The use of the anti-inflammatory drugs for the treatment of RA is associated with severe adverse reactions and toxicity. This limitation has necessitated the search for novel therapeutic products. We report here a traditional Chinese medicine-based herbal formula, Huo luo xiao ling dan (HLXL), which has potent antiarthritic activity as validated in the rat adjuvant-induced arthritis (AA) model. HLXL (2.3 g/Kg) was fed to Lewis (RT.1(1)) rats daily by gavage beginning at the onset of arthritis and then continued through the observation period. HLXL inhibited the severity of ongoing AA. This suppression of arthritis was associated with significant alterations in the T cell proliferative and cytokine responses as well as the antibody response against the disease-related antigen, mycobacterial heat-shock protein 65 (Bhsp65). There was a reduction in the level of the proinflammatory cytokines IL-17 and IL-1β but enhancement of the anti-inflammatory cytokine IL-10 level. In addition, there was inhibition of both the anti-Bhsp65 antibody response and the serum level of nitric oxide. Thus, HLXL is a promising CAM modality for further testing in RA patients.

A Th2 immune shift to heat shock protein 65 fails to arrest atherosclerosis: Proatherogenic role of Th2-deviated autoantibodies

Many reports regarding the cytotoxicity of antibodies to heat shock protein (HSP) 65/60 have implied the potential disadvantage and risk of HSP65/60-specific Th2 shifting strategy in arresting atherosclerosis. In this study, experiments were specifically designed to investigate the effect of a HSP65-specifc Th1 to Th2 immune shift accompanied with high-titer antibodies on atherosclerosis and explore the proatherogenic cytotoxicity of Th2-deviated anti-HSP65 antibodies to endothelial cells. Rabbits were nasally immunized with a fusion protein HSP65-6 x P277 10 times every other day. Immunologic results, including the repressed T-cell proliferation, increased interleukin-10 production and IgG1-predominated isotype of antibodies, revealed a significant Th1 to Th2 shift of response to HSP65. However, rabbits showed no reduction in atherosclerotic lesions. As a control, HSP65 immunization, which induced no antibodies, obviously attenuated atherosclerosis. Further studies on endothelial cells showed that the Th2-deviated anti-HSP65 antibodies could cross-react with HSP60 highly expressed in stressed cells and mediate damage to cells in the presence of complement. In conclusion, the Th2-deviated antibodies to HSP65 that were induced by over-regulated Th2 shift are cytotoxic to endothelial cells. This proatherogenic effect, in contradiction to the positive impact of Th1 suppression, can eventually invalidate the efficacy of Th2 shift in arresting atherosclerosis.