Triptolide Inhibits Expression of Inflammatory Cytokines and Proliferation of Fibroblast-like Synoviocytes Induced by IL-6/sIL-6R-Mediated JAK2/STAT3 Signaling Pathway

Triptolide,a component of the Chinese herb Tripterygium wilfordii Hook F,has been proved to be effective in the treatment of rheumatoid arthritis(RA).However,its underlying mechanisms on RA have not yet been well established.We observed the inhibitory effect of triptolide on the expression of inflammatory cytokines and proliferation of fibroblast-like synoviocytes(FLS)induced by the complex of interleukin-6(IL-6)and the soluble form of the IL-6 receptor(sIL-6R).Furthermore,to clarify the underlying mechanisms,we treated FLS with the Janus-activated kinase 2(JAK2)inhibitor/signal transducer and activator of transcription 3(STAT3)activation blocker AZD1480.In this study,immunohistochemical staining was used to identify vimentin(+)and CD68(−)in FLS.The FLS proliferation was measured by cell proliferation assay,and the cell cycles were analyzed by flow cytometry.Furthermore,ELISA was used to detect the expression of the inflammatory factors in culture solution.The expression levels of p-JAK2,JAK2,p-STAT3 and STAT3 were investigated through Western blotting analysis.The results showed that IL-6/sIL-6R significantly increased the cell proliferation and expression of inflammatory cytokines,including IL-6,interleukin-1β(IL-1β)and vascular endothelial growth factor(VEGF).Triptolide or AZD1480 inhibited the cell proliferation and inflammatory cytokine expression in IL-6/sIL-6R-stimulated FLS by suppressing JAK2/STAT3.The study suggested that the physiological effects of triptolide on RA were due to its contribution to the inhibition of the inflammatory cytokine expression and FLS proliferation by suppressing the JAK2/STAT3 signaling pathway.It may provide an innovative insight into the effect of triptolide in preventing RA pathogenesis.

Characterization of smooth muscle, enteric nerve, interstitial cells of Cajal, and fibroblast-like cells in the gastric musculature of patients with diabetes mellitus

AIM To investigate histologic abnormalities in the gastric smooth muscle of patients with diabetes mellitus(DM).METHODS Full-thickness gastric specimens were obtained from patients undergoing surgery for gastric cancer. H&E stain and Masson's Trichrome stain were performed to assess the degree of fibrosis. Immunohistochemical staining using various antibodies was also performed [antibodies against protein gene product 9.5(PGP9.5), neuronal nitric oxide synthase(n NOS), vasoactive intestinal peptide(VIP), neurokinin-1(NK1) receptor, c-Kit, and platelet-derived growth factor receptor-alpha,(PDGFRα)]. Immunofluorescent staining and evaluation with confocal microscopy were also conducted.RESULTS Twenty-six controls and 35 diabetic patients(21 shortduration patients and 14 long-duration patients) were included. There were no significant differences in basic demographics between the two groups except in mean body mass index(BMI)(higher in the DM group). Proportions of moderate-to-severe intercellular fibrosis in the muscle layer were significantly higher in the DM group than in the control group(P < 0.01). On immunohistochemical staining, c-Kit- and PDGFRα-positive immunoreactivity were significantly decreased in the DM group compared with the control group(P < 0.05). There were no statistically significant differences in PGP9.5, n NOS, VIP, and neurokinin 1 expression. On immunofluorescent staining, cellularity of interstitial cells of Cajal(ICC) was observed to decrease with increasing duration of DM.CONCLUSION Our study suggests that increased intercellular fibrosis, loss of ICC, and loss of fibroblast-like cells are found in the smooth muscle of DM patients. These abnormalities may contribute to changes in gastric motor activity in patients with DM.

Xeno-free culture of human spermatogonial stem cells supported by human embryonic stem cell-derived fibroblast-like cells

Spermatogonial stem cells （SSCs） divide continuously to support spermatogenesis throughout postnatal life and transmit genetic information to the next generation. Here, we report the successful establishment of the method for the isolation and identification of human SSCs from testicular tissue, and to determine the culture conditions required to expand SSCs on human embryonic stem cell-derived fibroblast-like cells （hdFs）. Large-scale cultures of SSCs were maintained on hdF feeder layers and expanded in the presence of a combination of cytokines and glial cell line-derived neurotrophic factor for at least 2 months. Cell surface marker analysis showed that SSCs retained high levels of alkaline phosphatase activity and stained strongly for anti-stage-specific embryonic antigen （SSEA）-1, OCT4 and CD49f. They also expressed the genes OCT4, SOX3 and STRA8 as detected by reverse transcription polymerase chain reaction （RT-PCR） analysis. These data clearly illustrate a novel approach for the growth of human SSCs using hdFs as feeder cells, potentially eliminating xenogeneic contaminants. This system provides a new opportunity for the study of the regulatory mechanism of the ‘niche＇ that governs SSC self-renewal, and will be a valuable source of SSCs for potential clinical applications.

Establishment and characterization of a fibroblast-like cell line from Anabarilius grahami （Cypriniformes： Cyprinidae）

Though Yurman province contains some 562 known species of fish, no cell lines from any of these have been made available to date. To protect germplasm resources and provide an effective tool in solving problems at cellular level of Anabarilius grahami, a fish endemic to Fuxian Lake, Yunnan, China, we established and characterized the major features of a continuous cell line （AGF II） from the caudal fin tissue of A. grahami. This AGF II cell line consists of fibroblast-like cells and has been subeultured more than 60 times over the course of a year. The cell line was maintained in DMEM/F12 supplemented with 10% FBS, with a cellular doubling time of 51.1 h. We continued with more experiments to optimize the culture and storage conditions, and found a variety of interesting results： cells could grow at temperature between 24 ~C and 28 ~C, with the optimal temperature of 28 ~C. Likewise, the growth rate ofA. grahami fin cells increased when the FBS proportion increased from 5% to 20%, with the optimal growth at the concentrations of 20% FBS, cells were able to grow in L-15 and DMEM/FI2 with optimal growth at L-15; DMSO is a better eryoprotectant than Glycerol, EG and MeOH for AGFII cells with optimal concentration of 5% DMSO. Chromosome analysis also showed that the distribution of chromosome number varies from 38 to 52, with a modal peak at 48 chromosomes, accounting for 39.8% of all cells. Using the same primer pairs specific to mtDNA, the AGF II cell sequences obtained by PCR were identical to those from muscle tissues ofA. grahami. Both chromosome analysis and PCR amplification confirmed the AGF II cells were from A. grahami, also indicating that that current long-term artificial propagation ofA. grahami has been successful. Finally, we noted that when cells were transfected with pEYFP-N1 and pECFP-N1 plasmid, bright fluorescent signals were observed, suggesting that this cell line may be suitable for use in transfection and future gene expression studies.

Establishment and characterization of a fibroblast-like cell line from Anabarilius grahami(Cypriniformes:Cyprinidae)

Though Yunnan province contains some 562 known species of fish,no cell lines from any of these have been made available to date.To protect germplasm resources and provide an effective tool in solving problems at cellular level of Anabarilius grahami,a fish endemic to Fuxian Lake,Yunnan,China,we established and characterized the major features of a continuous cell line(AGF II)from the caudal fin tissue of A.grahami.This AGF II cell line consists of fibroblast-like cells and has been subcultured more than 60 times over the course of a year.The cell line was maintained in DMEM/F12 supplemented with 10%FBS,with a cellular doubling time of 51.1 h.We continued with more experiments to optimize the culture and storage conditions,and found a variety of interesting results:cells could grow at temperature between 24℃and 28℃,with the optimal temperature of 28℃.Likewise,the growth rate of A.grahami fin cells increased when the FBS proportion increased from 5%to 20%,with the optimal growth at the concentrations of 20%FBS;cells were able to grow in L-15 and DMEM/F12 with optimal growth at L-15;DMSO is a better cryoprotectant than Glycerol,EG and MeOH for AGFII cells with optimal concentration of 5%DMSO.Chromosome analysis also showed that the distribution of chromosome number varies from 38 to 52,with a modal peak at 48 chromosomes,accounting for 39.8%of all cells.Using the same primer pairs specific to mtDNA,the AGF II cell sequences obtained by PCR were identical to those from muscle tissues of A.grahami.Both chromosome analysis and PCR amplification confirmed the AGF II cells were from A.grahami,also indicating that that current long-term artificial propagation of A.grahami has been successful.Finally,we noted that when cells were transfected with pEYFP-N1 and pECFP-N1 plasmid,bright fluorescent signals were observed,suggesting that this cell line may be suitable for use in transfection and future gene expression studies。

Protective effects of Dioscin on TNF-α-induced collagen-induced arthritis rat fibroblast-like synoviocytes involves in regulating the LTB4/BLT pathway

Background and Objective:LTB4 has been shown to be involved in rheumatoid arthritis(RA)pathogenesis.The effect of Dioscin(Dio)on the LTB4 pathway of RA have not been reported yet.This study aimed at further exploring whether Dioscin’s effects on TNF-αinduced collagen-induced arthritis(CIA)rat fibroblast-like synoviocytes(FLS)connected with the LTB4 and its receptor pathway.Materials&Methods:In this experiment,control group,TNF-αgroup,and different concentrations of Dioscin groups were established.Cell viability was evaluated using MTT assay.The levels of LTB4 in the samples of above groups were measured using ELISA.The mRNA expression levels of LTA4H,BLT1,and BLT2 were detected by quantitative real time PCR,while the expression level of LTA4H proteins were detected using western blot.The distribution of LTA4H was assessed by immunofluorescence assay.Results:the LTB4 level of TNF-αgroup in sample supernatant was higher than both control group and Dioscin groups with decreased LTB4 levels(p<0.05).Compared with the control group,the expression of LTA4H was significantly increased in TNF-αgroup(p<0.05),whereas LTA4H expressions were significantly decreased in all Dioscin groups when compared to TNF-αgroup(p<0.05).The mRNA expressions of BLT1 and BLT2 were markedly higher in TNF-αgroup than those in control group while Dioscin treatment significantly inhibited the increased expressions of BLT1 and BLT2 induced by TNF-α(p<0.05).Conclusions:These results firstly demonstrate that the protective effect of Dioscin on TNF-αinduced FLS may involve in its reducing LTB4 production by down-regulating LTA4H expression,and may inhibit its downstream pathway by decreasing LTB4 receptors levels.This findings suggest that dioscin produces a potential therapeutic effects for RA via its influencing LTA4H/LTB4/BLT pathway.

Cell Proliferation Ability of Mouse Fibroblast-Like Cells and Osteoblast-Like Cells on a Ti-6Al-4V Alloy Film Produced by Selective Laser Melting

Successful regeneration of tissues and organs relies on the application of suitable substrates or scaffolds in scaffold-based regenerative medicine. In this study, Ti-6Al-4V alloy films (Ti alloy film) were produced using a three-dimensional printing technique called Selective Laser Melting (SLM), which is one of the metal additive manufacturing techniques. The thickness of produced Ti alloy film was approximately 250 μm. The laser-irradiated surface of Ti alloy film had a relatively smooth yet porous surface. The non-irradiated surface was also porous but also retained a lot of partially melted Ti-6Al-4V powder. Cell proliferation ability of mouse fibroblast-like cells (L929 cells) and mouse osteoblast-like cells (MC3T3-E1 cells) on both the surfaces of Ti alloy film was examined using WST assay. Both L929 and MC3T3-E1 cells underwent cell proliferation during the culture period. These results indicate that selective laser melting is suitable for producing a cell-compatible Ti-6Al-4V alloy film for biomaterials applications.

Nuciferine alleviates collagen-induced arthritic in rats by inhibiting the proliferation and invasion of human arthritis-derived fibroblast-like synoviocytes and rectifying Th17/Treg imbalance

Rheumatoid arthritis(RA)is a chronic autoimmune disorder marked by persistent synovial inflammation and joint degradation,posing challenges in the development of effective treatments.Nuciferine,an alkaloid found in lotus leaf,has shown promising anti-inflammatory and anti-tumor effects,yet its efficacy in RA treatment remains unexplored.This study investigated the antiproliferative effects of nuciferine on the MH7A cell line,a human RA-derived fibroblast-like synoviocyte,revealing its ability to inhibit cell proliferation,promote apoptosis,induce apoptosis,and cause G1/S phase arrest.Additionally,nuciferine significantly reduced the migration and invasion capabilities of MH7A cells.The therapeutic potential of nuciferine was further evaluated in a collagen-induced arthritis(CIA)rat model,where it markedly alleviated joint swelling,synovial hyperplasia,cartilage injury,and inflammatory infiltration.Nuciferine also improved collagen-induced bone erosion,decreased pro-inflammatory cytokines and serum immunoglobulins(IgG,IgG1,IgG2a),and restored the balance between T helper(Th)17 and regulatory T cells in the spleen of CIA rats.These results indicate that nuciferine may offer therapeutic advantages for RA by decreasing the proliferation and invasiveness of FLS cells and correcting the Th17/Treg cell imbalance in CIA rats.

GRK2 mediated degradation of SAV1 initiates hyperplasia of fibroblast-like synoviocytes in rheumatoid arthritis

Hyperplasia and migration of fibroblast-like synoviocytes(FLSs)are the key drivers in the pathogenesis of rheumatoid arthritis(RA)and joint destruction.Abundant Yes-associated protein(YAP),which is a powerful transcription co-activator for proliferative genes,was observed in the nucleus of inflammatory FLSs with unknown upstream mechanisms.Using Gene Expression Omnibus database analysis,it was found that Salvador homolog-1(SAV1),the pivotal negative regulator of the Hippo-YAP pathway,was slightly downregulated in RA synovium.However,SAV1 protein expression is extremely reduced.Subsequently,it was revealed that SAV1 is phosphorylated,ubiquitinated,and degraded by interacting with an important serine-threonine kinase,G protein-coupled receptor(GPCR)kinase 2(GRK2),which was predominately upregulated by GPCR activation induced by ligands such as prostaglandin E2(PGE2)in RA.This process further contributes to the decreased phosphorylation,nuclear translocation,and transcriptional potency of YAP,and leads to aberrant FLSs proliferation.Genetic depletion of GRK2 or inhibition of GRK2 by paroxetine rescued SAV1 expression and restored YAP phosphorylation and finally inhibited RA FLSs proliferation and migration.Similarly,paroxetine treatment effectively reduced the abnormal proliferation of FLSs in a rat model of collagen-induced arthritis which was accompanied by a significant improvement in clinical manifestations.Collectively,these results elucidate the significance of GRK2 regulation of Hippo-YAP signaling in FLSs proliferation and migration and the potential application of GRK2 inhibition in the treatment of FLSs-driven joint destruction in RA.

改良组织块法分离培养佐剂性关节炎兔成纤维样滑膜细胞

目的 通过改良组织块细胞培养法,建立一种简单、可行的佐剂性关节炎兔成纤维样滑膜细胞（FLS）体外培养方法并观察细胞生物学特性.方法 通过注射弗氏完全佐剂建立关节炎模型,无菌条件下取佐剂性关节炎兔膝关节滑膜组织,剔净后剪成碎块,用灭菌滤纸吸掉组织上附着的水分,碎片接种于培养皿,观察细胞生长状况及形态特征.取第3代对数期细胞,用噻唑蓝（MTT）法绘制其生长曲线,并用免疫荧光法检测波形蛋白的表达情况.结果 体外培养的佐剂性关节炎兔FLS形态为长梭形纤维样,符合FLS的生长特征,免疫荧光检测显强表达波形蛋白.结论 改良组织块法可以分离培养出兔佐剂性关节炎成纤样维滑膜细胞,方法简便,成功率高,满足实验要求.

通过MC-Tryptase-PAR-2-FLS途径探讨资木瓜总苷对K/B×N小鼠血清转移性关节炎的治疗作用

目的:研究资木瓜总苷(TSCS)通过MC-Tryptase-PAR-2-FLS途径对K/B×N小鼠血清转移性关节炎的治疗作用。方法:小鼠随机分为6组:C57BL/6小鼠分别注射C57BL/6小鼠血清、K/B×N小鼠血清作为正常对照组和模型组,KitW-4Bao小鼠注射K/B×N小鼠血清作为阴性对照组,移植肥大细胞(MC)的KitW-4Bao小鼠随机分为3组:阳性药物(色甘酸钠)组、TSCS低、高剂量组,均注射K/B×N小鼠血清。游标卡尺测量小鼠关节肿胀度,HE染色观察关节形态学变化,甲苯胺蓝染色观察MC脱颗粒变化,免疫组化和qRT-PCR检测关节组织中类胰蛋白酶(Tryptase)、蛋白酶激活受体2(PAR-2)表达情况,ELISA检测血清IgG及关节中炎症因子含量变化。结果:KitW-4Bao小鼠对血清转移性关节炎抵抗,移植MC后,对K/B×N小鼠血清恢复敏感,引发关节炎。与模型组相比,TSCS高剂量组小鼠关节肿胀度、关节炎评分、病理学评分、MC脱颗粒率、Tryptase和PAR-2表达、血清IgG和炎症因子水平显著降低。结论:MC在K/B×N小鼠血清转移性关节炎模型中发挥重要作用;TSCS通过抑制MC脱颗粒释放类胰蛋白酶,影响MC-Tryptase-PAR-2-FLS通路,治疗K/B×N小鼠血清转移性关节炎。

Therapeutic effect of neohesperidin on TNF-α-stimulated human rheumatoid arthritis fibroblast-like synoviocytes

During the pathogensis of rheumatoid arthritis(RA),activated RA fibroblast-like synoviocytes(RA-FLSs)combines similar proliferative features as tumor and inflammatory features as osteoarthritis,which eventually leads to joint erosion.Therefore,it is imperative to research and develop new compounds,which can effectively inhibit abnormal activation of RA-FLSs and retard RA progression.Neohesperidin(Neo)is a major active component of flavonoid compounds with anti-inflammation and anti-oxidant properties.In this study,the anti-inflammation,anti-migration,anti-invasion,anti-oxidant and apoptosis-induced effects of Neo on RAFLSs were explored to investigate the underlying mechanism.The results suggested that Neo decreased the levels of interleukin IL-1β,IL-6,IL-8,TNF-α,MMP-3,MMP-9 and MMP-13 in FLSs.Moreover,Neo blocked the activation of the MAPK signaling pathway.Furthermore,treatment with Neo induced the apoptosis of FLSs,and inhibited the migration of FLSs.It was also found that Neo reduced the accumulation of reactive oxygen species(ROS)induced by TNF-α.Taken together,our results highlighted that Neo may act as a potential and promising therapeutic drug for the management of RA.

Tetrandrine inhibits migration and invasion of rheumatoid arthritis fibroblast-like synoviocytes through down-regulating the expressions of Rac1, Cdc42, and Rho A GTPases and activation of the PI3K/Akt and JNK signaling pathways

Tetrandrine （Tet）, the main active constituent of Stephania tetrandra root, has been demonstrated to alleviate adjuvant-induced arthritis in rats. The present study was designed to investigate the effects of Tet on the migration and invasion of rheumatoid arthritis fibroblast-like synovioeytes （RA-FLS） and explore the underlying mechanisms. By using cultures of primary FLS isolated from synoviums of RA patients and cell line MH7A, Tet （0.3, 1 μmol L-1） was proven to significantly impede migration and invasion of RA-FLS, but not cell proliferation. Tet also greatly reduced the activation and expressions of matrix degrading enzymes MMP-2/9, the expression of F-actin and the activation of FAK, which controlled the morphologic changes in migration process of FLS. To identify the key signaling pathways by which Tet exerts anti-migration effect, the specific inhibitors of multiple signaling pathways LY294002, Triciribine, SP600125, U0126, SB203580, and PDTC （against PI3K, Akt, JNK, ERK, p38 MAPK and NF-kB-p65, respectively） were used. Among them, LY294002, Triciribine, and SP600125 were shown to obviously inhibit the migration of MH7A cells. Consistently, Tet was able to down-regulate the activation of Akt and JNK as demonstrated by Western blotting assay. Moreover, Tet could reduce the expressions of migration-related proteins Rho GTPases Rac 1, Cdc42, and RhoA in MH7A cells. In conclusion, Tet can impede the migration and invasion of RA-FLS, which provides a plausible explanation for its protective effect on RA. The underlying mechanisms involve the reduction of the expressions of Racl, Cdc42, and RhoA, inhibition of the activation of Akt and JNK, and subsequent down-regulation of activation and/or expressions of MMP-2/9, F-actin, and FAK.

uPAR promotes tumor-like biologic behaviors of fibroblast-like synoviocytes through PI3K/Akt signaling pathway in patients with rheumatoid arthritis

Urokinase-type plasminogen activator receptor(uPAR),is a multifunctional receptor on cell surface,widely present in endothelial cells,fibroblasts,and a variety of malignant cells.Current studies have suggested that uPAR overexpressed on synovial tissues or in synovial fluid or plasma in patients with rheumatoid arthritis(RA).However,there are limited researches regarding the role of uPAR on fibroblast-like synoviocytes of rheumatoid arthritis(RA-FLSs)and its underlying mechanisms.Here,our studies show that the expression of uPAR protein was significantly higher in fibroblast-like synoviocytes(FLSs)from RA than those from osteoarthritis or traumatic injury patients.uPAR gene silencing significantly inhibited RA-FLSs cell proliferation,restrained cell transformation from the G0/G1 phase to S phase,aggravated cell apoptosis,interfered with RA-FLSs cell migration and invasion,and reduced activation of the PI3K/Akt signaling pathway,which may be associated withβ1-integrin.Cell supernatants from uPAR gene-silenced RA-FLSs markedly inhibited the migration and tubule formation ability of the HUVECs(a human endothelial cell line).Therefore,we demonstrate that uPAR changes the biological characteristics of RA-FLSs,and affects neoangiogenesis of synovial tissues in patients with RA.All of these may be associated with theβ1-integrin/PI3K/Akt signaling pathway.These results imply that targeting uPAR and its downstream signal pathway may provide therapeutic effects in RA.

Madecassoside impedes invasion of rheumatoid fibroblast-like synoviocyte from adjuvant arthritis rats via inhibition of NF-κB-mediated matrix metalloproteinase-13 expression

Fibroblast-like synoviocytes(FLS) play a pivotal role in Rheumatoid arthritis(RA) pathogenesis through aggressive migration and invasion. Madecassoside(Madec), a triterpenoid saponin present in Centella asiatica herbs, has a potent anti-inflammatory effect. In the present study, Madec exerted an obvious therapeutic effect in reversing the histological lesions in adjuvant-induced arthritis(AIA) rats. To recognize the anti-rheumatoid potentials of Madec, we further investigated whether Madec interfered with FLS invasion and metalloproteinase(MMP) expression. In cultures of primary FLS isolated from the AIA rats, Madec(10 and 30 μmol·L–1) was proven to considerably inhibit migration and invasion of FLS induced by interleukin 1β(IL-1β), but exhibiting no obvious effect on cell proliferation. Madec repressed IL-1β-triggered FLS invasion by prohibiting the expression of MMP-13. Additionally, Madec suppressed MMP-13 transcription via inhibiting the MMP-13 promoter-binding activity of NF-κB. Our results further showed that Madec down-regulated the translocation and phosphorylation of NF-κB as demonstrated by Western blotting and immunofluorescence assays. In conclusion, our results suggest that Madec exerts anti-RA activity via inhibiting the NF-κB/MMP-13 pathway.

Activation of human fibroblast-like synoviocytes by uric acid crystals in rheumatoid arthritis

Hyperuricemia-mediated uric acid crystal formation may cause joint inflammation and provoke the destruction of joints through the activation of inflammasome-mediated innate immune responses.However,the immunopathological effects and underlying intracellular regulatory mechanisms of uric acid crystal-mediated activation of fibroblast-like synoviocytes(FLS)in rheumatoid arthritis(RA)have not been elucidated.Therefore,we investigated the in vitro effects of monosodium urate crystals,alone or in combination with the inflammatory cytokines tumor-necrosis factor(TNF)-a or interleukin(IL)-1b,on the activation of human FLS from RA patients and normal control subjects and the underlying intracellular signaling mechanisms of treatment with these crystals.Monosodium urate crystals were able to significantly increase the release of the inflammatory cytokine IL-6,the chemokine CXCL8 and the matrix metalloproteinase(MMP)-1 from both normal and RA-FLS(all P,0.05).Moreover,the additive or synergistic effect on the release of IL-6,CXCL8 and MMP-1 from both normal and RA-FLS was observed following the combined treatment with monosodium urate crystals and TNF-a or IL-1b.Further experiments showed that the release of the measured inflammatory cytokine,chemokine and MMP-1 stimulated by monosodium urate crystals were differentially regulated by the intracellular activation of extracellular signal-regulated kinase and c-Jun N-terminal kinase pathways but not the p38 mitogen-activated protein kinase pathway.Our results therefore provide a new insight into the uric acid crystal-activated immunopathological mechanisms mediated by distinct intracellular signal transduction pathways leading to joint inflammation in RA.

Activity of fibroblast-like synoviocytes in rheumatoid arthritis was impaired by dickkopf-1 targeting siRNA

Background:Fibroblast-like synoviocytes(FLSs),resident mesenchymal cells of synovial joints,play an important role in the pathogenesis of rheumatoid arthritis(RA).Dickkopf-1(DKK-1)has been proposed to be a master regulator of bone remodeling in inflammatory arthritis.Here,potential impairation on the activity of FLSs derived from RA to small interfering RNAs(siRNAs)targeting DKK-1 was investigated.Methods:siRNAs targeting DKK-1 were transfected into FLSs of patients with RA.Interleukin(IL)-1β,IL-6,IL-8,matrix metalloproteinase(MMP)2,MMP3,MMP9,transforming growth factor(TGF)-pi,TGF-β2 and monocyte chemoattractant protein(MCP)-1 levels in the cell culture supernatant were detected by enzyme-linked immunosorbent assay(ELISA).Invasion assay and 3H incorporation assay were utilized to investigate the effects of siRNAs targeting DKK-1 on FLSs invasion and cell proliferation,respectively.Western blotting was performed to analyze the expression of nuclear factor(NF)-kB,interleukin-1 receptor-associared kinase(IRAK)1,extracellular regulated protein kinases(ERK)1,Jun N-terminal kinase(JNK)and p-catenin in FLSs.Results:DKK-1 targeting siRNAs inhibited the expression of DKK-1 in FLSs(P<0.01).siRNAs induced a significant reduction of the levels of IL-6,IL-8,MMP2,MMP3 and MMP9 in FLSs compared to the control group(P<0.05).DKK-1 targeting siRNAs inhibited the proliferation and invasion of FLSs(P<0.05).Important molecules of pro-inflammatory signaling in FLSs,including IRAKI and ERK1,were decreased by the inhibition of DKK-1 in FLSs.In contrast,β-catenin,a pivotal downstream molecule of the Wnt signaling pathway was increased.Conclusions:By inhibiting DKK-1,we were able to inhibit the proliferation,invasion and pro-inflammatory cytokine secretion of FLSs derived from RA,which was mediated by the ERK or the IRAK-1 signaling pathway.These data indicate the application of DKK-1 silencing could be a potential therapeutic approach to RA.

Targeted inhibition of GRK2 kinase domain by CP-25 to reverse fibroblast-like synoviocytes dysfunction and improve collagen-induced arthritis in rats

Rheumatoid arthritis(RA)is an autoimmune disease and is mainly characterized by abnormal proliferation of fibroblast-like synoviocytes(FLS).The up-regulated cellular membrane expression of G protein coupled receptor kinase 2(GRK2)of FLS plays a critical role in RA progression,the increase of GRK2 translocation activity promotes dysfunctional prostaglandin E4 receptor(EP4)signaling and FLS abnormal proliferation.Recently,although our group found that paeoniflorin-6’-O-benzene sulfonate(CP-25),a novel compound,could reverse FLS dysfunction via GRK2,little is known as to how GRK2 translocation activity is suppressed.Our findings revealed that GRK2 expression up-regulated and EP4 expression down-regulated in synovial tissues of RA patients and collagen-induced arthritis(CIA)rats,and prostaglandin E2(PGE2)level increased in arthritis.CP-25 could down-regulate GRK2 expression,up-regulate EP4 expression,and improve synovitis of CIA rats.CP-25 and GRK2 inhibitors(paroxetine or GSK180736 A)inhibited the abnormal proliferation of FLS in RA patients and CIA rats by down-regulating GRK2 translocation to EP4 receptor.The results of microscale thermophoresis(MST),cellular thermal shift assay,and inhibition of kinase activity assay indicated that CP-25 could directly target GRK2,increase the protein stability of GRK2 in cells,and inhibit GRK2 kinase activity.The docking of CP-25 and GRK2 suggested that the kinase domain of GRK2 might be an important active pocket for CP-25.G201,K220,K230,A321,and D335 in kinase domain of GRK2 might form hydrogen bonds with CP-25.Site-directed mutagenesis and co-immunoprecipitation assay further revealed that CP-25 down-regulated the interaction of GRK2 and EP4 via controlling the key amino acid residue of Ala321 of GRK2.Our data demonstrate that FLS proliferation is regulated by GRK2 translocation to EP4.Targeted inhibition of GRK2 kinase domain by CP-25 improves FLS function and represents an innovative drug for the treatment of RA by targeting GRK2.

Involvement of long non-coding RNAs in the pathogenesis of rheumatoid arthritis

Long non-coding RNA (lncRNA) plays a contributory role in rheumatoid arthritis (RA). In this review, we summarized the current findings of lncRNAs in RA, including cellular function and the potential mechanisms. Serum lncRNA levels are associated with serum proinflammatory cytokines and disease activity. LncRNAs regulate proliferation, migration, invasion and apoptosis of RA fibroblast-like synoviocytes (FLSs), modulate the differentiation of T lymphocytes and macrophages, and affect bone formationdestruction balance of chondrocytes. Besides, lncRNAs are involved in inflammation and cell motivation signaling pathways. Indepth research on lncRNAs may help elucidate the pathogenesis of RA and provides clues for novel treatment targets.