Neuroprotective Effects of Euonymus alatus Extract on Scopolamine-Induced Memory Deficits in Mice.

Euonymus alatus is considered to elicit various beneficial effects against cancer, hyperglycemia, menstrual discomfort, diabetic complications, and detoxification. The young leaves of this plant are exploited as food and also utilized for traditional medicine in East Asian countries, including Korea and China. Our preliminary study demonstrated that ethanolic extract from the Euonymus alatus leaf (EAE) exhibited the strongest antioxidant enzyme-inducing activity among more than 100 kinds of edible tree leaf extracts. This study investigated whether EAE could attenuate the cognitive deficits caused by oxidative stress in mice. Oral intubation of EAE at 100 mg/kg bw or higher resulted in significant improvements to the memory and behavioral impairment induced via i.p. injection of scopolamine. Furthermore, EAE enhanced the expression levels of hippocampal neurotrophic factors such as brain-derived neurotrophic factor (BDNF) and glial cell-derived neurotrophic factor in mice, activated the Nrf2, and the downstream heme oxygenase-1 (HO-1) a quintessential antioxidant enzyme. As rutin (quercetin-3-O-rutinose) was abundantly present in EAE and free quercetin was able to induce defensive antioxidant enzymes in an Nrf2-dependent manner, our findings suggested that quercetin derived from rutin via the intestinal microflora played a significant role in the protection of the mouse hippocampus from scopolamine-induced damage through BDNF-mediated Nrf2 activation, thereby dampening cognitive decline.

DC-Based Immunotherapy Combined with Low-Dose Methotrexate Effective in the Treatment of Advanced CIA in Mice.

We have previously demonstrated that semimature dendritic cell- (smDC-) based immunotherapy is effective for the treatment of collagen-induced arthritis (CIA) prior to disease onset. In the present study, we examined the efficacy of combination therapy with smDCs and methotrexate (MTX) in advanced CIA with a score of 2-3. Combination therapy with low-dose MTX and type II collagen- (CII-) pulsed smDCs (CII-smDCs) was more effective in inhibiting disease progression than high or low-dose MTX alone or a combination of high dose MTX and CII-smDCs. The effect of CII-smDCs alone was also comparable to the combination therapy. CD4(+)Foxp3(+) Treg populations and IL-10 secretion markedly increased, and CII-specific autoreactive T cells decreased in mice treated with CII-smDCs alone or in combination with MTX. Combination therapy reduced the secretion of interferon-γ (IFN-γ) and IL-17 with little influence on the IL-4 secretion in the mixed leukocyte reaction. These results imply that the combination therapy with low-dose MTX and smDCs is effective in controlling advanced CIA by enhancing Treg population and suppresses antigen-specific Th1/Th17 immunity, rather than initiating Th1 to Th2 immune deviation. Our findings provide a better understanding of the DC therapy in combination with MTX for the treatment of patients with rheumatoid arthritis (RA).

Interleukin-17 increases the expression of Toll-like receptor 3 via the STAT3 pathway in rheumatoid arthritis fibroblast-like synoviocytes.

We examined the effect of interleukin-17 (IL-17) on the expression of Toll-like receptors (TLRs) in fibroblast-like synoviocytes (FLS) from patients with rheumatoid arthritis (RA) and osteoarthritis (OA). We investigated the region downstream of IL-17 for TLR expression. We also investigated the downstream signals responsible for the effect of IL-17 in TLR expression. Levels of IL-17 protein in the serum and synovial fluid of RA and OA patients were measured by ELISA. The IL-17 mRNA expression in peripheral blood mononuclear cells and synovial fluid mononuclear cells was measured by RT-PCR. RA and OA FLS were incubated with IL-17 and/or IL-23 for 24 hr. To block the signal transducer and activator of transcription 3 (STAT3) pathway, FLS were treated with S3I-201 before incubation with IL-17 and IL-23. Synovial tissue samples from RA and OA patients were stained with antibodies to IL-17, TLR2, TLR3, TLR4, STAT3 and phospho-STAT3. Levels of IL-17 protein were higher in the serum and synovial fluid from RA patients compared with those from OA patients. The IL-17 mRNA expression in synovial fluid monocytes was also higher in RA than in OA patients. Immunohistochemical staining showed greater expression of IL-17, TLR2, TLR3 and TLR4 in synovial samples from RA compared with OA patients. Interleukin-17 increased the expression of TLR2, TLR3 and TLR4 in RA FLS; IL-23 augmented the IL-17-induced expression of TLR2, TLR3 and TLR4 in RA FLS. Blocking STAT3 with S3I-201 reduced IL-17-induced TLR3 expression in RA FLS. Our results suggest that IL-17 is a major cytokine in pathogenesis on RA. The IL-17 influences the innate immune system by increasing the synovial expression of TLR2, TLR3 and TLR4. We may control TLR3 expression via the STAT3 pathway in RA FLS.

Rebamipide suppresses collagen-induced arthritis through reciprocal regulation of th17/treg cell differentiation and heme oxygenase 1 induction.

OBJECTIVE: Rebamipide, a gastroprotective agent, has the ability to scavenge reactive oxygen radicals. Increased oxidative stress is implicated in the pathogenesis of rheumatoid arthritis (RA). We undertook this study to investigate the impact of rebamipide on the development of arthritis and the pathophysiologic mechanisms by which rebamipide attenuates arthritis severity in a murine model of RA. METHODS: Collagen-induced arthritis (CIA) was induced in DBA/1J mice. Anti-type II collagen antibody titers and interleukin-17 (IL-17) levels were determined using enzyme-linked immunosorbent assay. The expression of transcription factors was analyzed by immunostaining and Western blotting. Frequencies of IL-17-producing CD4+ T cells (Th17 cells) and CD4+CD25+FoxP3+ Treg cells were analyzed by flow cytometry. RESULTS: Rebamipide reduced the clinical arthritis score and severity of histologic inflammation and cartilage destruction in a dose-dependent manner. The joints isolated from rebamipide-treated mice with CIA showed decreased expression of nitrotyrosine, an oxidative stress marker. Rebamipide-treated mice showed lower circulating levels of type II collagen-specific IgG, IgG1, and IgG2a. Whereas the number of Th17 cells in spleens was decreased in rebamipide-treated mice with CIA, a significant increase in the number of Treg cells in spleens was observed. In vitro, rebamipide inhibited Th17 cell differentiation through STAT-3/retinoic acid receptor-related orphan nuclear receptor γt and reciprocally induced Treg cell differentiation through FoxP3. Rebamipide increased Nrf2 nuclear activities in murine CD4+ T cells and LBRM-33 murine T lymphoma cells. Heme oxygenase 1 (HO-1) expression in the spleens was markedly increased in rebamipide-treated mice. CONCLUSION: The inhibitory effects of rebamipide on joint inflammation are associated with recovery from an imbalance between Th17 cells and Treg cells and with activation of an Nrf2/HO-1 antioxidant pathway.

Grape-seed proanthocyanidin extract as suppressors of bone destruction in inflammatory autoimmune arthritis.

Chronic autoimmune inflammation, which is commonly observed in rheumatoid arthritis (RA), disrupts the delicate balance between bone resorption and formation causing thedestruction of the bone and joints. We undertook this study to verify the effects of natural grape-seed proanthocyanidin extract (GSPE), an antioxidant, on chronic inflammation and bone destruction. GSPE administration ameliorated the arthritic symptoms of collagen-induced arthritis (CIA), which are representative of cartilage and bone destruction. GSPE treatment reduced the formation of tartrate-resistant acid phosphatase (TRAP)-positive multinucleated cells and osteoclast activity and increased differentiation of mature osteoblasts. Receptor activator of NFκB ligand expression in fibroblasts from RA patients was abrogated with GSPE treatment. GSPE blocked human peripheral blood mononuclear cell-derived osteoclastogenesis and acted as an antioxidant. GSPE improved the arthritic manifestations of CIA mice by simultaneously suppressing osteoclast differentiation and promoting osteoblast differentiation. Our results suggest that GSPE may be beneficial for the treatment of inflammation-associated bone destruction.

IL-32 and IL-17 interact and have the potential to aggravate osteoclastogenesis in rheumatoid arthritis.

INTRODUCTION: Interleukin (IL)-32 and IL-17 play critical roles in pro-inflammatory responses and are highly expressed in the synovium of patients with rheumatoid arthritis (RA). We investigated the relations between these two cytokines (IL-17 and IL-32) for their ability to induce each other and to stimulate osteoclasts in RA fibroblast-like synoviocytes (FLSs) and T cells. METHODS: FLSs were isolated through surgical synovectomy obtained from patients with RA or osteoarthritis (OA). Real-time PCR were performed to evaluate the expression of IL-32, IL-17 and osteoclast-related genes. Immunohistochemical staining and tartrate-resistant acid phosphatase (TRAP) staining were performed to determine the distribution of inflammatory cytokines and the presence of osteoclastogenesis. RESULTS: IL-17 induced the expression of IL-32 in the FLSs from RA patients, as assessed by microarray. IL-32 production was increased by IL-17. IL-32 in the FLSs from RA patients induced the production of IL-17 in CD4+ T cells. IL-32 and IL-17 were colocalized near TRAP-positive areas in joint specimens. IL-17 and IL-32 synergistically induced the differentiation of osteoclasts, as demonstrated by the expression of osteoclast-related genes. IL-32 and IL-17 also could induce resorption by osteoclasts in a RANKL-dependent manner. CONCLUSIONS: IL-17 affected the expression of IL-32 in FLSs of RA patients and IL-32 induced the production of IL-17 in CD4+ T cells. Both IL-17 and IL-32 cytokines can reciprocally influence each other's production and amplify the function of osteoclastogenesis in the in RA synovium. Separately, IL-17 and IL-32 each stimulated osteoclastogenesis without RANKL. Together, the two cytokines synergistically amplified the differentiation of osteoclasts, independent of RANKL stimulation.

Interleukin-22 promotes osteoclastogenesis in rheumatoid arthritis through induction of RANKL in human synovial fibroblasts.

OBJECTIVE: To examine the regulatory role of interleukin-22 (IL-22) in the expression of RANKL and induction of osteoclastogenesis in rheumatoid arthritis (RA). METHODS: Concentrations of IL-22 and RANKL in the serum and synovial fluid of RA patients were measured using enzyme-linked immunosorbent assay. RA synovial fibroblasts were treated with recombinant human IL-22 (rhIL-22), and the expression of RANKL messenger RNA (mRNA) and protein was measured using real-time polymerase chain reaction, Western blotting, and intracellular immunostaining. Human monocytes were cocultured with IL-22-prestimulated RA synovial fibroblasts and macrophage colony-stimulating factor, and osteoclastogenesis was assessed by counting the multinucleated cells (those staining positive for tartrate-resistant acid phosphatase). RESULTS: The IL-22 concentration in the synovial fluid was higher in RA patients than in patients with osteoarthritis (OA). The serum IL-22 concentration was also higher in RA patients than in OA patients and healthy volunteers, and this correlated with serum titers of rheumatoid factor and anti-cyclic citrullinated peptide antibodies. In RA synovial fibroblasts treated with rhIL-22, the expression of RANKL mRNA and protein was increased in a dose-dependent manner. IL-22-induced RANKL expression was down-regulated significantly by the inhibition of p38 MAPK/NF-κB or JAK-2/STAT-3 signaling. In human monocytes cocultured with IL-22-prestimulated RA synovial fibroblasts in the absence of exogenous RANKL, the monocytes differentiated into osteoclasts, but this osteoclastogenesis decreased after p38 MAPK/NF-κB or JAK-2/STAT-3 signaling was inhibited. CONCLUSION: These results show that IL-22 up-regulates RANKL expression in RA synovial fibroblasts and induces osteoclastogenesis. These effects are mediated by the p38 MAPK/NF-κB and JAK-2/STAT-3 signaling pathways.

IL-17 increases cadherin-11 expression in a model of autoimmune experimental arthritis and in rheumatoid arthritis.

IL-17 plays important roles in synovial inflammation and bone destruction in the mouse model of autoimmune arthritis and in rheumatoid arthritis (RA). Cadherin-11 determines the behavior of synovial cells in their proinflammatory and destructive tissue response in inflammatory arthritis, and promotes the invasive behavior of fibroblast-like synoviocytes (FLS). The purpose of this study was to examine the effect of IL-17 on the expression of cadherin-11 in autoimmune experimental arthritis and in RA synovium. The severity of synovial inflammation and bone destruction were examined in IL-17-injected knee joints of mice with collagen-induced arthritis (CIA). Cadherin-11 expression was examined in the synovium of mice with CIA, of IL-1 receptor antagonist (IL-1Ra)-deficient mice and of patients with RA and osteoarthritis (OA). Cadherin-11 expression was also examined in the synovium of IL-17 injected knee joints from CIA mice and in IL-17-stimulated FLS of CIA mice and RA patients. IL-17 aggravated synovial inflammation and bone destruction in CIA. By immunohistochemistry, cadherin-11 expression was increased in the synovium of mice with CIA and IL-1Ra-deficient mice and in patients with RA. Synovial cadherin-11 expression in IL-17-injected knee joints, measured by real-time RT-PCR, Western blot and immunohistochemistry, was increased in CIA. Cadherin-11 expression was significantly increased by IL-17 in cultured FLS of CIA mice and RA patients, and these increases were blocked by NF-κB inhibitors. IL-17 increased the expression of cadherin-11 in vivo and in vitro, which implies that an IL-17-induced increase of cadherin-11 is involved in IL-17-induced aggravation of joint destruction and inflammation.

Grape seed proanthocyanidin extract (GSPE) differentially regulates Foxp3(+) regulatory and IL-17(+) pathogenic T cell in autoimmune arthritis.

Grape seed proanthocyanidin extract (GSPE), which is the antioxidant derived from grape seeds, has been reported to possess a variety of potent properties. We have previously shown that GSPE attenuates collagen-induced arthritis. However the mechanism by which GSPE regulates the immune response remains unclear, although it may involve effects on the regulation of pathogenic T cells in autoimmune arthritis. To clarify this issue, we have assessed the effects of GSPE on differential regulation of Th17 and regulatory T (Treg) cells subsets in vitro in mouse and human CD4(+) T cells. We observed that GSPE decreased the frequency of IL-17(+)CD4(+)Th17 cells and increased induction of CD4(+)CD25(+)forkhead box protein 3 (Foxp3)(+) Treg cells. In vivo, GSPE effectively attenuated clinical symptoms of established collagen-induced arthritis in mice with concomitant suppression of IL-17 production and enhancement of Foxp3 expression (type II collagen-reactive Treg cells) in CD4(+) T cells of joints and splenocytes. The presence of GSPE decreased the levels of IL-21, IL-22, IL-26 and IL-17 production by human CD4(+) T cells in a STAT3-dependent manner. In contrast, GSPE induces Foxp3(+) Treg cells in humans. Our results suggest that GSPE possesses a reciprocal control over IL-17 and Foxp3. By potently regulating inflammatory T cell differentiation, GSPE may serve as a possible novel therapeutic agent for inflammatory and autoimmune diseases, including rheumatoid arthritis.

NF-kappaB inhibition leads to increased synthesis and secretion of MIF in human CD4+ T cells.

To examine the effects of nuclear factor kappa B (NF-kappaB) inhibition on the secretion of macrophage migration inhibitory factor (MIF) in human CD4(+) T cells. Isolated human CD4(+) T cells were cultured for 24h with pharmacological inhibitors of NF-kappaB including parthenolide, pyrrolidine dithiocarbamate, BAY 11-7082, gliotoxin, oridonin, andrographolide, and NF-kappaB shRNA. MIF concentration was measured by intracellular flow cytometry, enzyme-linked immunosorbent assay, and real-time polymerase chain reaction. The intracellular concentrations O(2)(-), H(2)O(2), and glutathione were measured using the oxidation-sensitive fluorescent dyes dihydroethidium, dichlorodihydrofluorescein diacetate, and monochlorobimane, respectively. The amount of phosphorylated c-Jun was measured by Western blotting. Treatment of CD4(+) T cells with NF-kappaB inhibitors significantly increased MIF concentration in culture supernatants, MIF gene expression, and O(2)(-) production, and decreased the intracellular concentrations of MIF, H(2)O(2), and glutathione. Treatment with LY294002 (PI3K inhibitor) and SP600125 (JNK inhibitor) suppressed NF-kappaB inhibitor induced MIF mRNA expression and MIF secretion. LY294002 and SP600125 inhibited the parthenolide-induced phosphorylation of c-Jun. Treatment with H(2)O(2) decreased the amount of intracellular MIF protein and increased MIF concentration in the culture supernatant. N-acetylcysteine, an antioxidant precursor of glutathione, inhibited the parthenolide-induced and H(2)O(2)-induced secretion of MIF. These results indicate that pharmacological inhibition of NF-kappaB causes the release of MIF through de novo synthesis of MIF and the secretion of preformed MIF in CD4(+) T cells through the production of reactive oxygen species.

Grape seed proanthocyanidin extract (GSPE) attenuates collagen-induced arthritis.

To examine whether grape seed proanthocyanidin extract (GSPE) which is known to act as an antioxidant has therapeutic effect on collagen-induced arthritis (CIA) in mice, an animal model of rheumatoid arthritis. Mice were treated with an intraperitoneal injection of GSPE (10, 50, or 100 mg/kg) or saline. Clinical, histological, and biochemical parameters were assessed. The effects of GSPE on osteoclastogenesis were determined by tartrate-resistant acid phosphatase (TRAP) staining of the inflamed joints and bone-marrow cells cultured with the receptor activator of nuclear factor B ligand (RANKL) and macrophage colony-stimulating factor (M-CSF). Intracellular levels of hydrogen peroxide were determined using carboxy-dichlorodihydrofluorescein diacetate. GSPE treatment significantly attenuated the severity of CIA in a dose-dependent manner and reduced the histology scores for synovial inflammation, cartilage erosion, bone erosion, and the number of TRAP+ osteoclasts. GSPE treatment significantly reduced the numbers of tumor necrosis factor alpha (TNF-alpha)- or interleukin 17 (IL-17)-producing cells in the synovial tissue and the spontaneous production of TNF-alpha and IL-17 by splenocytes compared with those in the control mice. The serum levels of type-II-collagen-specific IgG2a and plasma levels of 8-isoprostane in the GSPE-treated mice were significantly lower than those in the control mice. GSPE dose-dependently suppressed osteoclastogenesis in vitro. GSPE significantly reduced hydrogen peroxide production by anti-CD3-monoclonal-antibody-stimulated CD4+ splenocytes. These results indicate that intraperitoneal injection of GSPE attenuated CIA in mice. GSPE may be useful in the treatment of rheumatoid arthritis.