Interleukin (IL)-27 is a novel cytokine of the IL-6/IL-12 family that has been reported to be involved in the pathogenesis of autoimmune diseases and has a pivotal role as both a pro- and anti-inflammatory cytokine. We investigated the in vivo effects of IL-27 on arthritis severity in a murine collagen-induced arthritis (CIA) model and its mechanism of action regarding control of regulatory T (Tregs) and IL-17-producing T helper 17 (Th17) cells. IL-27-Fc-treated CIA mice showed a lower severity of arthritis. IL-17 expression in the spleens was significantly decreased in IL-27-Fc-treated CIA mice compared with that in the CIA model. The Th17 population was decreased in the spleens of IL-27-Fc-treated CIA mice, whereas the CD4+CD25+Foxp3+ Treg population increased. In vitro studies revealed that IL-27 inhibited IL-17 production in murine CD4+ T cells, and the effect was associated with retinoic acid-related orphan receptor γT and signal transducer and activator of transcription 3 inhibition. In contrast, fluorescein isothiocyanate-labeled forkhead box P3 (Foxp3) and IL-10 were profoundly augmented by IL-27 treatment. Regarding the suppressive capacity of Treg cells, the proportions of CTLA-4+ (cytotoxic T-lymphocyte antigen 4), PD-1+ (programmed cell death protein 1) and GITR+ (glucocorticoid-induced tumor necrosis factor receptor) Tregs increased in the spleens of IL-27-Fc-treated CIA mice. Furthermore, in vitro differentiated Treg cells with IL-27 exerted a more suppressive capacity on T-cell proliferation. We found that IL-27 acts as a reciprocal regulator of the Th17 and Treg populations in CD4+ cells isolated from healthy human peripheral blood mononuclear cells (PBMCs), as well as from humans with rheumatoid arthritis (RA) PBMCs. Our study suggests that IL-27 has the potential to ameliorate overwhelming inflammation in patients with RA through a reciprocal regulation of Th17 and Treg cells.
collagen-induced arthritis; interleukin-27; interleukin-17-producing T cells; regulatory T cells; rheumatoid arthritis
In this study we examined the in vivo and in vitro effects and mechanisms of action of curcumin on the development of acute graft-versus-host disease (GVHD) using a murine model.
Mixed lymphocyte reactions were used to determine the in vitro effects of curcumin. Treatment with curcumin attenuated alloreactive T cell proliferation and inhibited the production of interferon (IFN)-γ and interleukin (IL)-17. In a murine acute GVHD model, transplantation of curcumin-treated allogeneic splenocytes into irradiated recipient mice significantly reduced the clinical severity scores of acute GVHD manifested in the liver, skin, colon and lung as compared with animals receiving vehicle-treated splenocytes. c-Fos and c-Jun expression levels in the skin and intestine, which are major target organs, were analyzed using immunohistochemical staining. Expression of both proteins was reduced in epithelial tissues of skin and intestine from curcumin-treated GVHD animals. The IFN-γ-expressing CD4+ splenocytes and IFN-γ-expressing lymph node cells were dramatically decreased in curcumin-treated mice. In contrast, CD4+Foxp3+ splenocytes were increased in the curcumin-treated acute GVHD animals. Flow cytometric analysis revealed that animals transplanted with curcumin-treated allogeneic splenocytes showed increased populations of CD4+ regulatory T cells (Tregs) as well as CD8+ Treg cells, compared to animals administered vehicle-treated splenocytes. Curcumin-treated acute GVHD animals could have a change in B cell subpopulations.
In the present study, we investigated the efficacy and mechanism of action of curcumin treatment against acute GVHD. The acute GVHD mice administered with curcumin-treated splenocytes showed significantly reduced severity of acute GVHD. Curcumin exerted in vivo preventive effects on acute GVHD by reciprocal regulation of T helper 1 (Th1) and Treg (both CD4+ and CD8+ Treg) cell lineages as well as B cell homeostasis.
We aimed to quantify periarticular osteoporosis and investigate its significance in 45 patients with rheumatoid arthritis (RA) and 106 controls. Dual-energy X-ray absorptiometry (DXA) was used to determine the ratio of shaft to periarticular bone mineral density (BMD) as an index of periarticular demineralization. Periarticular osteoporosis was measured by conventional radiography. The BMDs of shaft and periarticular regions in eight designated areas on proximal phalanges were quantified. Clinical variables were examined to identify risk factors for periarticular osteoporosis. The assessment of periarticular osteoporosis on X-ray images reached a moderate degree of interobserver agreement among four physicians (ĸ = 0.47). For BMD quantification, we designed three types of mathematical formulae: the ratio of shaft to periarticular BMD, the mean of the ratios, and the ratio of the sums. These ratios were significantly higher in the patients with early RA (disease duration ≤ 3 yr) than in controls (P < 0.01). The findings were not as distinctive in patients with established RA. Body mass index, cumulative dose of corticosteroid, and C-terminal telopeptide were correlated with BMD ratios. Conclusively, DXA-assisted localized quantification and BMD ratio calculations are feasible for assessing periarticular demineralization. Periarticular osteoporosis is a relatively distinctive feature of early RA.
Bone Density; Arthrits; Rheumatoid; Periarticular Osteopenia
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.
White fat cells secrete adipokines that induce inflammation and obesity has been reported to be characterized by high serum levels of inflammatory cytokines such as IL-6 and TNF-α. Rheumatoid arthritis (RA) is a prototype of inflammatory arthritis, but the relationship between RA and obesity is controversial. We made an obese inflammatory arthritis model: obese collagen-induced arthritis (CIA). C57BL/6 mice were fed a 60-kcal high fat diet (HFD) from the age of 4 weeks and they were immunized twice with type II collagen (CII). After immunization, the obese CIA mice showed higher arthritis index scores and histology scores and a more increased incidence of developing arthritis than did the lean CIA mice. After treatment with CII, mixed lymphocyte reaction also showed CII-specific response more intensely in the obese CIA mice than lean CIA. The anti-CII IgG and anti-CII IgG2a levels in the sera of the obese CIA mice were higher than those of the lean CIA mice. The number of Th17 cells was higher and the IL-17 mRNA expression of the splenocytes in the obese CIA mice was higher than that of the lean CIA mice. Obese CIA mice also showed high IL-17 expression on synovium in immunohistochemistry. Although obesity may not play a pathogenic role in initiating arthritis, it could play an important role in amplifying the inflammation of arthritis through the Th1/Th17 response. The obese CIA murine model will be an important tool when we investigate the effect of several therapeutic target molecules to treat RA.
arthritis, experimental; inflammation; mice; obesity; Th17 cells
The interleukin-33 (IL-33)/ST2 pathway has emerged as an intercellular signaling system that participates in antigen-allergen response, autoimmunity and fibrosis. It has been suggested that IL-33/ST2 signaling has been involved in the pathogenesis of rheumatoid arthritis (RA), because IL-33 and its receptor have been specifically mapped to RA synovium. The aim of this study was to determine the levels of IL-33 and sST2 in sera and synovial fluids in patients with RA. The serum level of IL-33 was significantly higher in patients with RA (294.9 ± 464.0 pg/mL) than in healthy controls (96.0 ± 236.9 pg/mL, P = 0.002). The synovial fluid level of IL-33 was significantly higher in RA patients than in osteoarthritis patients. The level of serum sST2 was higher in RA patients than in healthy controls (P = 0.042). A significant relationship was found between the levels of IL-33 and IL-1β (r = 0.311, P = 0.005), and IL-33 and IL-6 (r = 0.264, P = 0.017) in 81 RA patients. The levels of IL-33, sST2 and C-reactive protein decreased after conventional disease-modifying antirheumatic drugs treatment in 10 patients with treatment-naïve RA. Conclusively, IL-33 is involved in the pathogenesis of RA and may reflect the degree of inflammation in patients with RA.
Interleukin-33; sST2, ST2L; Arthritis, Rheumatoid
B cells play an important role in the pathogenesis of rheumatoid arthritis (RA). High levels of B cell activating factor (BAFF) are detected in autoimmune diseases. BAFF and BAFF receptor (BAFF-R) are expressed in B and T cells of RA synovium. The study was undertaken to identify the NF-κB signal pathway involved in the induction of BAFF-R in human B cells. Immunohistochemical staining of NF-κB p65, NF-κB p50, BAFF, and BAFF-R was performed on sections of synovium from severe and mild RA and osteoarthritis (OA) patients. Peripheral blood mononuclear cells (PBMCs) were isolated from control and RA patients and B cells were isolated from controls. BAFF-R was analyzed by flow cytometry, realtime PCR and confocal staining after treatment with NF-κB inhibitors. NF-κB p65, NF-κB p50, BAFF, and BAFF-R were highly expressed in severe RA synovium relative to mild RA synovium or OA synovium. BAFF-R expression was reduced by NF-κB inhibitors in PBMCs and B cells from normal controls. We also showed reduction in expression of BAFF-R via inhibition of the NF-κB pathway in PBMCs of RA patients. BAFF/BAFF-R signaling is an important mechanism of pathogenesis in RA and that BAFF-R reduction by NF-κB blocking therapy is another choice for controlling B cells in autoimmune diseases such as RA.
B-cell activation factor receptor; B-cell activating factor; B-lymphocytes; NF-κB; rheumatoid arthritis
The purpose of this study was to investigate the expression of IL-16 in the rheumatoid synovium and the role of inflammatory cytokines and Toll-like receptor (TLR) ligands in IL-16 production by fibroblastlike synoviocytes (FLS) of rheumatoid arthritis (RA) patients. Immunohistochemical staining was performed with a monoclonal antibody to IL-16 in synovial tissues from patients with RA and likewise in patients with osteoarthritis (OA). FLS were isolated from RA synovial tissues and stimulated with IL-15, IL-1β, IFN-γ, and IL-17. The IL-16 mRNA level was assessed by semiquantitative RT-PCR and real time (RT) PCR and a comparison was made between IL-16 mRNA levels produced by RA-FLS and OA-FLS. Production of IL-16 was identified by a western blot assay, and IL-16 production after stimulation by specific ligands of TLR2 and TLR4 was assessed by RT-PCR. While immunohistochemical staining demonstrated strong expression of IL-16 mRNA in synovial tissues from patients with RA, similar findings were not present in the OA group. Moreover, mRNA expression of IL-16 by RA-FLS increased after treatment with IL-17 but not with IL-15, IL-1β, and IFN-γ. Specifically, IL-17 increased IL-16 mRNA level by RA-FLS and peripheral blood mononuclear cells in a dose-dependent manner. However, IL-17 did not stimulate IL-16 production in OA-FLS. Peptidoglycan, a selective TLR2 ligand, also increased production of IL-16 by RA-FLS dosedependently, whereas LPS, a selective TLR4 ligand, had no such stimulatory effect. The results from our data demonstrate that IL-17 and TLR2 ligands stimulate the production of IL-16 by RA-FLS.
interleukin-16; interleukin-17; rheumatoid arthritis; synovial membrane; Toll-like receptors
The present study was devised to understand the role of systemic indoleamine 2,3-dioxygenase (IDO) in the tolerance induction for orally tolerized mice in collagen-induced arthritis (CIA). We examined whether IDO-expressing dendritic cells (DCs) are involved in the generation of CD4+CD25+ regulatory T cells during the induction of oral tolerance in a murine CIA model.
Type II collagen was fed six times to DBA/1 mice beginning 2 weeks before immunization, and the effect on arthritis was assessed. To examine the IDO expression, the DCs of messenger RNA and protein were analyzed by RT-PCR and Flow cytometry. In addition, a proliferative response assay was also carried out to determine the suppressive effects of DCs through IDO. The ability of DCs expressing IDO to induce CD4+CD25+ T regulatory cells was examined.
CD11c+ DCs in Peyer's patches from orally tolerized mice expressed a higher level of IDO than DCs from nontolerized CIA mice. IDO-expressing CD11c+ DCs were involved in the suppression of type II collagen-specific T-cell proliferation and in the downregulation of proinflammatory T helper 1 cytokine production. The suppressive effect of IDO-expressing CD11c+ DCs was mediated by Foxp3+CD4+CD25+ regulatory T cells.
Our data suggest that tolerogenic CD11c+ DCs are closely linked with the induction of oral tolerance through an IDO-dependent mechanism and that this pathway may provide a new therapeutic modality to treat autoimmune arthritis.
Polychondritis is an inflammatory disorder that affects various catilagenous structures, and the clinical features include auricular, nasal and respiratory tract chondritis. It also involves the eyes, audiovestibular apparatus, joints and vascular structures. Polychondritis can be associated with several rheumatologic diseases such as systemic lupus erythematosus, rheumatoid arthritis and systemic vasculitis. However, polychondritis is a rare complication of Behçet's disease (BD) and only ten cases with combined BD and polychondritis have been reported on around the world. In this report, we describe a 40-year-old Korean man with BD who suffered from polychondritis that manifested as bilateral auricular chondritis, conjunctivitis and arthritis.
Polychondritis; Behçet's disease