CYP7B expression and activity in fibroblast-like synoviocytes from patients with rheumatoid arthritis: regulation by proinflammatory cytokines

OBJECTIVE: The cytochrome P450 enzyme CYP7B catalyzes the conversion of dehydroepiandrosterone (DHEA) into 7alpha-hydroxy-DHEA (7alpha-OH-DHEA). This metabolite can stimulate the immune response. We previously reported that the severity of murine collagen-induced arthritis is correlated with CYP7B messenger RNA (mRNA) expression and activity in the arthritic joint. The purpose of this study was to investigate the presence of 7alpha-OH-DHEA in synovial samples and the cytokine regulation of CYP7B activity in fibroblast-like synoviocytes (FLS) from patients with rheumatoid arthritis (RA). METHODS: The presence of 7alpha-OH-DHEA was examined in synovial biopsy tissues, synovial fluid, and serum by radioimmunoassay. The effect of cytokines on CYP7B mRNA expression and CYP7B activity in FLS was examined by determining the formation of the CYP7B enzyme product 7alpha-OH-DHEA with the use of high-performance liquid chromatography. RESULTS: The CYP7B enzyme product 7alpha-OH-DHEA was found in synovial biopsy tissues, synovial fluid, and serum from RA patients. The proinflammatory cytokines tumor necrosis factor alpha (TNFalpha), interleukin-1alpha (IL-1alpha), IL-1beta, and IL-17 up-regulated CYP7B activity in an FLS cell line 2-10-fold. Enhanced CYP7B activity was correlated with an increase in CYP7B mRNA. The cytokine transforming growth factor beta inhibited CYP7B activity. Moreover, CYP7B activity was detected in 10 of 13 unstimulated synovial fibroblast cell lines. Stimulation with TNFalpha increased CYP7B activity in all cell lines tested. CONCLUSION: Exposure to the proinflammatory cytokines TNFalpha, IL-1alpha, IL-1beta, and IL-17 increases CYP7B activity in synovial tissue. Increased CYP7B activity leads to higher levels of the DHEA metabolite 7alpha-OH-DHEA in synovial fluid, which may contribute to the maintenance of the chronic inflammation observed in RA patients.     

High concentration simvastatin induces apoptosis in fibroblast-like synoviocytes from patients with rheumatoid arthritis

OBJECTIVE: We previously reported that 10 mg/day of simvastatin significantly reduced clinical scores of rheumatoid arthritis (RA) in patients with active RA with hypercholesterolemia. We have also reported that a certain pharmacological concentration of simvastatin, i.e., 0.05-0.1 microM, inhibits the production of interleukin 6 (IL-6) and IL-8 and the cell proliferation induced by tumor necrosis factor-alpha (TNF-alpha) in fibroblast-like synoviocytes (FLS) derived from patients with RA in vitro. We investigated other effects of simvastatin on FLS from the standpoint of cell viability and apoptosis. METHODS: RA FLS were cultured with or without 0.05-50 microM simvastatin for 48 h. Cell viability was determined using 3-(4,5-dimethylthiazol-2-yl)-2,5-diphenyltetrazolium bromide (MTT) assay. Apoptosis was measured by flow cytometric analysis using propidium iodide and annexin-V. Caspase-3 and -9 activities were analyzed by colorimetric assays. RESULTS: High concentrations of simvastatin, i.e., 1.0-50 microM, reduced cell viability and induced prominent apoptosis in FLS in a dose-dependent manner. The apoptosis induced by simvastatin was caspase-3- and caspase-9-dependent. These effects were completely reversed in the presence of mevalonic acid or geranylgeranyl-pyrophosphate, but not in the presence of farnesyl-pyrophosphate. Further, a geranylgeranyl transferase inhibitor and a RhoA kinase inhibitor mimicked the effect of simvastatin. CONCLUSION: These data, together with our previous report, suggest that low (pharmacological range) and high concentrations of simvastatin affect FLS differently: (1) at a low concentration, it inhibits IL-6 and IL-8 production and the cell proliferation of FLS induced by TNF-alpha (2) at high concentrations, it induces apoptosis in FLS. Understanding this dose-dependent biphasic effect of simvastatin may prove important for its clinical applications in the treatment of RA.     

Fibroblast-like synoviocytes from patients with rheumatoid arthritis are more sensitive to apoptosis induced by the viral protein, apoptin, than fibroblast-like synoviocytes from trauma patients

OBJECTIVE: Fibroblast-like synoviocytes (FLS) from patients with rheumatoid arthritis (RA) show characteristics of transformation. Because the chicken anemia virus protein, apoptin, induces apoptosis solely in transformed cells, it was investigated whether FLS from patients were more sensitive to apoptin-induced apoptosis than FLS from normal joints obtained from trauma patients. METHODS: FLS were transduced with maltose-binding protein (MBP)-apoptin recombinant protein or MBP as a control protein by microinjection. After 24 hours, cells were fixed and stained with immunofluorescence to detect apoptin or MBP and the number of dead cells was assessed. Furthermore, phosphorylation of apoptin was analysed in FLS from patients with RA and from trauma patients by in vitro kinase assay. RESULTS: FLS from patients with RA were significantly more sensitive to apoptin-induced apoptosis than FLS from trauma patients (p = 0.0263). Furthermore, MBP-apoptin induced more apoptosis than MBP in RA FLS (p = 0.004). No phosphorylation of apoptin was observed in FLS from patients with RA. DISCUSSION: FLS from patients with RA are more sensitive to apoptin-induced apoptosis than normal FLS, which is consistent with a transformed phenotype of these cells. However, given the lack of phosphorylation of apoptin in RA FLS the mechanism of action of apoptin seems to differ between tumour cells and RA FLS.This study indicates that apoptin may help to identify a new therapeutic pathway against hyperplasia of the synovium and joint destruction in RA.     

Effects of estrogen on interleukin-6 production in rheumatoid fibroblast-like synoviocytes

OBJECTIVE: In view of the importance of estrogen and IL-6 in the pathogenesis of rheumatoid arthritis (RA), the effects of 17 beta-estradiol (E2) on interleukin (IL)-6 production in cultured rheumatoid fibroblast-like synoviocytes were investigated. METHODS: Cultured fibroblast-like synoviocytes obtained from RA joints were treated with the vehicle (control), as well as 10(-8) and 10(-6) M of E2, with or without IL-1 beta stimulation. After 72 hours of culture, the levels of IL-6 in supernatants were measured by ELISA. RESULTS: Treatment with 10(-8) and 10(-6) M of E2 had no effect on the constitutive production of IL-6 in cultured fibroblast-like synoviocytes. However, E2 increased IL-1 beta-induced IL-6 production in a dose-dependent manner, with a mean 12.5% increase with 10(-8) M of E2 (p = 0.048) and 33.4% with 10(-6) M (p < 0.0001) versus the control. CONCLUSION: Estrogen up-regulates IL-1 beta-induced IL-6 production in cultured fibroblast-like synoviocytes, possibly contributing to the enhancement of rheumatoid inflammation in synovial tissues.     

Taurine chloramine inhibition of cell proliferation and cytokine production by rheumatoid arthritis fibroblast-like synoviocytes

OBJECTIVE: To examine whether taurine (Tau) or its physiologic chlorinated derivative, taurine chloramine (Tau-CI), affects proliferation of, and proinflammatory cytokine (interleukin-6 [IL-6] and IL-8) production by, fibroblast-like synoviocytes (FLS) isolated from rheumatoid arthritis (RA) patients. METHODS: FLS, isolated from the synovial tissue of 19 RA patients and cultured in vitro for 3-6 passages, were stimulated with the recombinant human cytokines IL-1beta (1 ng/ml), tumor necrosis factor alpha (TNFalpha; 10 ng/ml), or IL-17 (10 ng/ml) in the presence of either Tau or Tau-Cl, which were added at concentrations of 50-500 microM. Tau and Tau-Cl were added simultaneously with, 2 hours before, or 24 hours after the stimuli. The concentrations of IL-6 and IL-8 were determined in culture supernatants using specific enzyme-linked immunosorbent assays. Proliferation of FLS was estimated on the basis of 3H-thymidine incorporation into the cells, which were cultured for 72 hours in the presence of recombinant human basic fibroblast growth factor (bFGF) (1 ng/ml) and Tau or Tau-Cl, which were added simultaneously at the beginning of the culture. RESULTS: Cultured in vitro, RA FLS spontaneously secreted low levels of IL-6 and IL-8, but when RA FLS were stimulated with IL-1beta, TNFalpha, or IL-17, significantly higher amounts of IL-6 and IL-8 were produced. Tau-Cl, but not Tau, inhibited cytokine-triggered synthesis of IL-6 (50% inhibitory concentration [IC50] approximately 225 microM) and IL-8 (IC50 approximately 450 microM) when added simultaneously with the stimuli. However, IL-17-induced production of IL-8 was not affected by Tau-Cl. In the cells prestimulated with IL-1beta for 24 hours, Tau-Cl still inhibited synthesis of IL-6, but did not affect IL-8 production. Moreover, Tau-Cl inhibited spontaneous and bFGF-triggered proliferation of FLS in a dose-dependent manner. Neither Tau nor Tau-Cl affected cell viability. CONCLUSION: The results of these studies demonstrate that Tau-Cl inhibits production of proinflammatory cytokines by RA FLS, as well as proliferation of these cells. Thus, Tau-Cl may act as a physiologic modulator of FLS functions related to their pathogenic role in RA.     

Thioredoxin 1 is associated with the proliferation and apoptosis of rheumatoid arthritis fibroblast-like synoviocytes

We aimed to investigate the possible effects of thioredoxin 1 (Trx1) on the proliferation and apoptosis of rheumatoid arthritis fibroblast-like synoviocytes (RA-FLSs) and elucidate the possible mechanisms involved. We investigated the distribution and expression of Trx1 in synovial tissues from RA and osteoarthritis (OA) patients by immunohistochemistry and real-time polymerase chain reaction (RT-PCR) analyses. RA-FLSs were isolated and cultured under normoxic (21% oxygen) or hypoxic (3% oxygen) concentrations. Transfection of Trx1-siRNAs and a Trx1 overexpression construct was conducted to manipulate the expression of Trx1. Protein expression was detected by Western blot. Doxorubicin (Adriamycin, ADR) was used to induce apoptosis. LY-294002 was used for the inhibition of PI3K-Akt. Cell proliferation and apoptosis were determined by MTS (3-[4,5-dimethylthiazol-2-yl]-5-[3-carboxymethoxyphenyl]-2-[4-sulfophenyl]-2H-tetrazolium, inner salt) assay and flow cytometry, respectively. The mRNA and protein expression of Trx1 in RA tissues was higher than that in OA tissues. The expression levels of Trx1 and cell proliferation in RA-FLSs were increased under hypoxia in comparison to those under normoxia. In hypoxia, downregulation of Trx1 significantly suppressed FLS proliferation, and the expression of PI3Kp85, phospho-Akt, and Bcl-2, while notably increased FLS apoptosis and the expression of active Caspase3 and Bax. In normoxia, Trx1 overexpression promoted the FLS proliferation and the expression of PI3Kp85, phospho-Akt, and Bcl-2, but inhibited FLS apoptosis and the expression of active Caspase3 and Bax in FLSs. Such effects were partially repressed by LY-294002 treatment. Trx1 may play an important role in regulating the proliferation and apoptosis of RA-FLSs by modulating PI3K-Akt activation.     

Production of interleukin-6 and interleukin-8 by nurse-like cells from rheumatoid arthritis patients after stimulation with monocytes

It has been reported that nurse-like cells (NLCs) play a critical role in the pathogenesis of rheumatoid arthritis (RA). The interaction between NLCs established from RA patients (RA-NLCs), and freshly isolated blood monocytes was analyzed to further elucidate the pathogenesis of RA. RA-NLC lines were established from the synovium of RA patients. The RA-NLCs were cultured with monocytes freshly isolated from peripheral blood of healthy donors, and induction of interleukin (IL)-6 and IL-8 as well as the mRNA expression of these cytokines was examined. The levels of IL-6 were over 400 times higher in the supernatant from coculture of RA-NLCs and monocytes than in those from cultures of RA-NLCs alone. Anti-tumor necrosis factor (TNF)-α monoclonal antibody inhibited the induction of both cytokine in a dose-dependent fashion, although there was no detectable level of TNF-α in the supernatant from coculture. In addition, coculture of RA-NLCs and monocytes without direct cell contact did not induce cytokine production. To determine IL-6 producing cells, RA-NLCs and monocytes were separated into each fraction after coculture for 24 h. Cocultured RA-NLCs contained approximately 80 times higher IL-6 mRNA than the RA-NLCs cultured alone. The levels of IL-8 were also much higher (about 900 times) in the supernatant from coculture than in those from cultures of RA-NLCs alone. Cocultured RA-NLCs expressed IL-8 mRNA about 620 times higher than those cultured alone. These results indicate that NLCs produce high levels of IL-6 and IL-8 after cell–cell interaction with monocytes/macrophages via membrane-bound TNF-α, and that activation of NLCs by monocytes/macrophages may be involved in the pathogenesis of RA through maintenance of synovial inflammation.     

Production of interleukin-6 and interleukin-8 by nurse-like cells from rheumatoid arthritis patients after stimulation with monocytes

Abstract

It has been reported that nurse-like cells (NLCs) play a critical role in the pathogenesis of rheumatoid arthritis (RA). The interaction between NLCs established from RA patients (RA-NLCs), and freshly isolated blood monocytes was analyzed to further elucidate the pathogenesis of RA. RA-NLC lines were established from the synovium of RA patients. The RA-NLCs were cultured with monocytes freshly isolated from peripheral blood of healthy donors, and induction of interleukin (IL)-6 and IL-8 as well as the mRNA expression of these cytokines was examined. The levels of IL-6 were over 400 times higher in the supernatant from coculture of RA-NLCs and monocytes than in those from cultures of RA-NLCs alone. Anti-tumor necrosis factor (TNF)-α monoclonal antibody inhibited the induction of both cytokine in a dose-dependent fashion, although there was no detectable level of TNF-α in the supernatant from coculture. In addition, coculture of RA-NLCs and monocytes without direct cell contact did not induce cytokine production. To determine IL-6 producing cells, RA-NLCs and monocytes were separated into each fraction after coculture for 24?h. Cocultured RA-NLCs contained approximately 80 times higher IL-6 mRNA than the RA-NLCs cultured alone. The levels of IL-8 were also much higher (about 900 times) in the supernatant from coculture than in those from cultures of RA-NLCs alone. Cocultured RA-NLCs expressed IL-8 mRNA about 620 times higher than those cultured alone. These results indicate that NLCs produce high levels of IL-6 and IL-8 after cell–cell interaction with monocytes/macrophages via membrane-bound TNF-α, and that activation of NLCs by monocytes/macrophages may be involved in the pathogenesis of RA through maintenance of synovial inflammation.     

脐带间充质干细胞对类风湿关节炎滑膜成纤维细胞基质金属蛋白酶的影响

目的探讨脐带间充质干细胞（UCMSCs）对 RA 滑膜成纤维细胞（FLSs）分泌 MMPs 的影响。方法 Wistar 大鼠制作胶原诱导关节炎（CIA）模型，第17天尾静脉输注1×106 UCMSCs，第42天处死大鼠后收集滑膜组织提取 RNA，实时荧光定量 PCR 检测滑膜组织 MMP-1、MMP-3、MMP-13的表达水平。取行膝关节置换术的 RA 和 OA 患者滑膜组织，分离培养 FLSs，比较 RA 与 OA FLSs 的 MMP-1、MMP-3和 MMP-13的表达水平。将 RA FLSs 与 UCMSCs 用 Transwell 小室共培养72 h，配对 t 检验比较共培养前后 FLSs 的 MMPs 表达水平变化及上清中 MMPs 含量，并检测 UCMSCs 在共培养过程中分泌的可溶性细胞因子水平。向培养体系中加入可溶性细胞因子的抑制剂后观察 FLSs 表达 MMPs 水平变化。2组间比较采用 t 检验，而3组及以上之间比较采用单因素方差分析。结果 CIA 大鼠滑膜组织较正常鼠高表达 MMP-1（6.9±5.4，1.3±1.4，P<0.05）、MMP-3（6.0±6.5，1.4±1.0，P<0.05）和 MMP-13（21.8±20.8，1.5±1.6， P<0.05），UCMSCs 治疗后与未治疗组及成纤维细胞治疗组比较，滑膜组织 MMP-1（1.3±1.4，6.9±5.4，8.7±6.8，P<0.05）、MMP-3（1.4±1.5，6.0±6.5，6.0±5.7，P<0.05）和 MMP-13（3.0±3.2，22±21，22±26，P<0.05）均表达下调。 RA 患者 FLSs MMP-1（1.8±0.9，0.9±0.7，t=2.44，P<0.05）、MMP-3（2.6±1.7，1.1±1.0，t=2.25，P<0.05）和MMP-13（2.4±2.3，0.6±0.7，t=2.37，P<0.05）水平明显高于 OA 患者。经 UCMSCs 体外共培养后，MMP-13（1.3±1.2，0.9±1.2，t=3.63，P<0.05）水平下调，而 MMP-1（1.5±1.4，6.6±6.0，t=3.90，P<0.05）、MMP-3（7±17，22±35，t=2.86，P<0.05）上调。共培养后 UCMSCs 表达 IDO、肝细胞生长因子（HGF）和 IL-10等可溶性细胞因子水平明显增多。加入 IL-10抗体后 UCMSCs 抑制 MMP-13的能力减弱。结论 UCMSCs 通过分泌可溶性细胞因子 IL-10抑制 RA 滑膜组织 MMPs 分泌，从而改善关节炎病情。     

Osteoprotegerin and receptor activator of nuclear factor kappaB ligand expression in fibroblast-like synoviocytes from rheumatoid arthritis and osteoarthritis patients

SIR, We read with interest the article by Haynes et al. [1]reporting the expression of osteoprotegerin (OPG) and receptoractivator of nuclear factor B ligand (RANKL) in synovial tissuesfrom patients with arthritis, including rheumatoid arthritis(RA). They showed that OPG was expressed predominantly in macrophagesin the synovial lining layer and in endothelial cells, and expressionwas decreased in patients with active RA compared with thosewith osteoarthritis (OA), inactive RA and spondyloarthropathies.In contrast, RANKL expression was seen in active RA synovialtissues,     

Effect of nuclear factor-kappaB inhibition on rheumatoid fibroblast-like synoviocytes and collagen induced arthritis

OBJECTIVE: The nuclear factor-kB (NF-kB) signaling pathway has been implicated as a molecular target for the treatment of various inflammatory diseases, such as rheumatoid arthritis (RA). In particular, IkB kinase (IKK) is considered an important molecular target because the majority of inflammatory signaling pathways mediated by NF-kB involve IKK activation. We investigated the effect of NF-kB inhibition on rheumatoid fibroblast-like synoviocytes (FLS) and collagen induced arthritis. METHODS: We evaluated the effect of IMD-0560, an inhibitor of IKK, on rheumatoid FLS in vitro and on collagen type II induced arthritis in mice. RESULTS: IMD-0560 suppressed the nuclear translocation of NF-kB and phosphorylation of IkBa induced by tumor necrosis factor-a in FLS. In addition, this compound suppressed the production of inflammatory cytokines, including interleukin 6 (IL-6), IL-8, and monocyte chemoattractant protein-1. IMD-0560 also inhibited the proliferation of FLS without showing cellular toxicity. Finally, this compound was effective against collagen induced arthritis in mice. CONCLUSION: Based on these results, IMD-0560 could be a new therapeutic agent for RA.     

Geranylgeranylacetone, a non-toxic inducer of heat shock protein, induces cell death in fibroblast-like synoviocytes from patients with rheumatoid arthritis

Fluvastatin (Fluv) is reported to induce apoptosis in rheumatoid arthritis (RA) synoviocytes through the blocking of protein geranylgeranylation. We report here our investigation of whether geranylgeranylacetone (GGA) induces cell death in RA synoviocytes. Synovial tissues were obtained from patients with RA at the time of total knee arthroplasty. Fibroblast-like synoviocytes (FLS) cultured in three passages were used for the experiments. The FLS were then cultured for 48 h in 48-well flat-bottomed plates containing various concentrations of GGA (0.1–4.0 μg/ml) and either 0.1 or 0.5 μM Fluv. We also examined the effect of GGA and Fluv in human fibroblasts from normal skin (CCD-25SK) and FLS from patients with osteoarthritis (OA). Cells demonstrating cell death were counted following trypan blue staining. In the absence of GGA, there was no apparent cell death, as evidence by trypan blue staining. Concentrations of GGA between 0.1 and 4.0 μg/ml induced cell death in RA FLS, but not in skin fibroblasts (CCD-25SK) nor OA FLS. The number of synoviocytes demonstrating cell death induced by 0.1 or 0.5 μM Fluv was significantly higher than that by the medium alone. In summary, we found that GGA induced cell death in RA FLS, suggesting that GGA may be a potential new therapeutic agent for RA as well as osteoporosis.