[Mechanism of Huangqin Qingre Chubi Capsules in improving rheumatoid arthritis based on METTL3-SFRP4/Wnt/ß-catenin pathway].

The effect and mechanism of Huangqin Qingre Chubi Capsules(HQC) on rheumatoid arthritis(RA) were studied.Seventy male SPF rats were randomly divided into normal group, model group, low-(0. 18 g·kg~(-1)), middle-(0. 36 g·kg~(-1)), and high-(0. 72 g·kg~(-1)) dose groups of HQC, methotrexate group(MTX, 0. 75 mg·kg~(-1)), and negative control group(NC group, model +saline). Adjuvant arthritis fibroblast-like synoviocytes(AA-FLS) were divided into normal group, model group, low-, middle-, and high-dose groups of HQC, and negative control group. RT-qPCR and Western blot were used to detect the m RNA and protein expressions of METTL3, SFRP4, ß-catenin, CCND1, c-Myc, MMP3, and fibronectin. The protein expression of MMP3 and ß-catenin was detected by immunofluorescence. The gene expression level of METTL3 on AA-FLS was knocked down to further examine the expression of each gene. ELISA measured the levels of IL-1ß, IL-6, and IL-8. The results showed that compared with the normal group, rats in the model group found redness and swelling in their limbs and significantly increased joint swelling. Compared with the model group, the joint swelling degree of each treatment group significantly decreased(P<0. 05). The paw retraction threshold and body weight mass index both significantly increased(P<0. 05). METTL3 was highly expressed on AA and negatively correlated with the expression of SFRP4. After treatment, the m RNA and protein expression of METTL3, ß-catenin, CCND1, c-Myc, fibronectin, and MMP3 were significantly decreased on AA-FLS(P< 0. 05). Compared with the model group, knocking down METTL3 resulted in reduced m RNA and protein expression of ß-catenin, CCND1, c-Myc, fibronectin, and MMP3(P< 0. 05). At the same time, the m RNA and protein expressions of ß-catenin, CCND1, c-Myc, fibronectin, and MMP3 in the HQC+METTL3 knockdown group were significantly lower than those in the METTL3 knockdown group(P<0. 05). HQC could reduce the levels of IL-1ß, IL-6, and IL-8 to varying degrees(P<0. 05). The results indicate that HQC has a significant improvement effect on arthritis in AA rats. The expression of METTL3 is significantly increased in synovial tissue and AA-FLS of AA rats, which may be a potential target for the diagnosis and treatment of RA. HQC improves RA through the METTL3-SFRP4/Wnt/ß-catenin signaling pathway and has significant antiinflammatory and anti-rheumatic effects.

[Effect of Flavonoids from Wang Zaizi on Adjuvant Arthritis in Rats and Its Mechanism].

OBJECTIVE: The therapeutic effect and mechanism of total flavonoids in Isodon amethystoides (Ben-th) Cy Wu et Hsuan (TFIA) on adjuvant arthritis (AA) were investigated. METHODS: AA model rats were set and complete Freund's adjuvant injection,randomly divided into 4 groups: AA group,AA+TFIA 50 mg/kg group,AA+TFIA 100 mg/kg group,AA+TFIA 150 mg/kg group,and each group has 10 rats. Blank control group was set without modeling (n=10). Four days post-modeling rats in each TFIA groups were treated once a day with TFIA at 50 mg/kg,100 mg/kg and 150 mg/kg for 24 d,and rats in blank control and AA groups were given saline as control. At the 12th day,16th day,20th day and 24th day of treatment,the effect of TFIA on AA rats was evaluated by rat arthritis score. Then the rats were sacrificed on the 24th day of treatment,and the synovial tissue of rats was isolated and the fibroblast-like synoviocytes (FLS) were primary cultured. The expressions of IL-1 in FLS was detected by ELISA,the FLS proliferation activity was detected by MTT assay,and the expression of miR-152,ß-catenin and cyclin D1 gene (ccnd1) were detected by real time qPCR. MiR-152 mimics and NC mimics (control) were transfected into FLS in AA rats,and miR-152 inhibitors and NC inhibitors (control) were transfected into FLS in AA+TFIA 100 mg/kg group rats. The expressions of miR-152,ß-catenin, ccnd1, IL-1 and FLS proliferation were detected 36 h post-transfection. RESULTS: TFIA significantly inhibited the arthritis socre of rats and the expressions of ß-catenin, ccnd1, IL-1 and the proliferation of FLS in AA rats (P<0.05). There was no significant difference between the dose groups,all of which were significant when compared with the blank control group (P<0.05). Compared with the control group,the expression of miR-152 in AA group was significantly decreased (P<0.05). After transfection of miR-152 mimics into AA FLS,overexpression of miR-152 significantly inhibited the expressions of ß-catenin, ccnd1, IL-1 and the proliferation of FLS (P<0.05). After transfection of miR-152 inhibitors into FLS from AA+TFIA 100 mg/kg group,inhibition of miR-152 significantly promoted the expressions of ß-catenin, ccnd1, IL-1 and the proliferation of FLS. CONCLUSION: TFIA has a certain therapeutic effect on AA rats via the up-regulation of miR-152 expression,possibly affecting the classical Wnt signaling pathway.

[Experimental Study on Paeoniflorin Inhibiting mTOR Signaling Pathway in Adjuvant Arthritis Rats].

OBJECTIVE: To study the effect of paeoniflorin (PF) on mTOR signal in synovial fibroblast-like synoviocytes (FLS) in rats with adjuvant arthritis. METHODS: AA model rats were prepared by complete Freun's adjuvant injection in foot-plantar, the PF was injected to rats in AA + PF 100 µg / mL group, AA + PF 200 µg / mL group and AA + PF 400 µg / mL group by the tail vein injection at the dose of 0.1 mL/200 g body mass, and the effects of three doses of PF on arthritis scores in AA rats were studied. The modeling rats and control rats were sacrificed at 28 d after modeling, then the synovium was separeated from rat articular, the FLS were cultured. The effect of PF on the expression of mTOR and MMP3 in AA FLS was detected by the real time qPCR. The effect on the cytokine IL-1, IL-6 was detected by ELISA, and the Western blot was used to investigate the role of PF in the mTOR phosphorylation. Furthermore, FLS were transfected with mTOR vectors, and the effect of mTOR overexpression on the PF roles was detected by real time qPCR and ELISA. RESULTS: The tail vein injection of PF can significantly reduce the AA rat arthritis score. Compared with AA group, the expression of mTOR in AA+PF 1 µg/mL, AA+PF 2 µg/mL, AA+PF 4 µg/mL was significantly decreased at 48 h after dosing. Compared with AA group, the relative expression of p-mTOR protein in PF 2 µg/mL group was also decreased. Compared with AA group at 48 h after dosing, the levels of IL-1, IL-6 and MMP3 in AA+PF 1 µg/mL, AA+PF 2 µg/mL, AA+PF 4 µg/ mL were significantly decreased, respectively. Compared with PF 2 µg/mL group, the relative expression of IL-1, IL-6 and MMP3 in PF 2 µg/mL+mTOR vectors was increased. CONCLUSION: PF can significantly inhibit the pathology of AA rats, and its mechanism may be related to the inhibition of mTOR signal in FLS of AA rats.

[Molecular mechanism of total flavonoids in Isodon amethystoides on adjuvant arthritis in rats].

Our preliminary study showed that the total flavonoids in Isodon amethystoides(TFIA), a local medicinal herb in Suzhou, had a certain therapeutic effect on adjuvant arthritis, and this therapeutic effect may be achieved through the up-regulation of miR-152 expression. In this paper, the molecular mechanism of TFIA on the pathogenesis of adjuvant arthritis(AA) rats was further studied. AA rats were prepared with complete Freund's adjuvant, and then treated with TFIA by intragastric administration. Real-time qPCR was used to detect the effects of TFIA on the negative regulatory loop of miR-152, methylase DNMT1 and methyl-CpG binding protein MeCP2 in fibroblast like synoviocytes(FLS) of AA rats, as well as the effects of TFIA on the classic Wnt signaling pathway and the expression of fibronectin gene in AA rats. Intragastric administration of TFIA significantly inhibited the expression of DNMT1 and reversed the negative regulatory loop composed of miR-152, DNMT1 and MeCP2 in the pathology of AA rats. After transfection of miR-152 inhibitors into the FLS in treatment group, DNMT1 expression was significantly restored. TFIA significantly up-regulated the expression of SFRP4 and inhibited the expression of ß-catenin, C-myc and ccnd1, the key genes of canonical Wnt signaling pathway. TFIA also significantly inhibited the expression of fibronectin, an AA gene. The effect of TFIA on the expression of SFRP4, ß-catenin, C-myc, ccnd1 and fibronectin was reversed after transfection with miR-152 inhibitors in the treatment group FLS. TFIA may inhibit the DNMT1 expression, up-regulate the SFRP4 expression, inhibit the expression of classical Wnt signaling genes ß-catenin, C-myc, and ccnd1 as well as the RA gene fibronectin expression through the up-regulation of miR-152 expression.

[Treatment of rheumatoid arthritis with flavonoids of Echinps latifolius Tausch in rat model].

OBJECTIVE: To investigate the effect of Flavonoids extracted from Echinps latifolius Tausch(FELT) on rheumatoid arthritis (RA) in rat model. METHOD: Fifty SD rats were randomly divided into model group, control group, and low, medium, and high-dose FELT groups (n=10 in each group). Complete Freund's adjuvant (0.1 mL) was used to induce RA in rats. FELT in doses of 50 mg/kg, 100 mg/kg, 150 mg/kg was given to rats in low, medium and high-dose FELT groups by gavage, and same volume of PBS was given to rats in control group. The arthritis score and the paw swelling score were measured to evaluate the therapeutic effect of FELT. Real time qPCR was used to detect the mRNA expression of fibronectin and MMP3 in synovial tissue and the mRNA expression of caspase 3, Bcl-2 and Bcl-2 associated X protein (Bax) in fibroblast-like synoviocytes (FLS). RESULTS: The arthritis score and the paw swelling score were significantly decreased in three FELT groups compared to RA model rats (P <0.05). The relative expression levels of FN and MMP3 mRNA in synovium of three FELT-treatment groups were significantly lower than those in model group (1.80, 1.76 and 1.67 vs 2.53; 1.69, 1.46 and 1.45 vs 2.67, respectively, all P <0.05). The relative expression levels of Bax and caspase 3 mRNA in FLSs of three FELT groups were higher than those in model group (0.56, 0.58 and 0.60 vs 0.30; 0.54, 0.56 and 0.59 vs 0.29, respectively, all P <0.05); while the relative expression levels of Bcl-2 mRNA in FELT groups were lower than that in model group (2.20, 2.08 and 2.08 vs 4.04, respectively, P <0.05). CONCLUSION: FELT may inhibit the synovium proliferation in RA model rats through promoting the FLS apoptosis.

[Effect of Phellinus Polysaccharide on Canonical Wnt Signaling in Synovium in Rats with Rheumatoid Arthritis].

OBJECTIVE: To investigate the role of Phellinus Polysaccharide (FPS) in activating canonical Wnt signaling in rats with rheumatoid arthritis (RA). METHODS: Male SD rats were randomly divided into three groups (normal group, RA model group and PPS treated RA group), each with 10 rats. The RA model rats were prepared through intradermal injection of 0. 1 mL complete Freund's adjuvant into the right rear toes of the rats. The PPS treated RA rats were given 50 mg/kg PPS by gavage eight days after the introduction of RA. All rats were evaluated with arthritis score and paw swelling score at day 16, 20, 24, 28, 32. At day 28, the expressions of fibronectin gene, Wnt signal pathway negative regulation gene SFRP1,2 and Wnt key gene ß-catenin, C-myc, and ccndl were detected by real time qPCR. RESULTS: PPS significantly reduced the arthritis score and paw swelling score of RA model rats. Lower levels of expression of SFRP1, 2 and higher levels of expression of ß-catenin, C-myc, ccndl and fibronectin were found in the RA model rats compared with the normal controls. PPS increased the expression of SFRP1, 2 and decreased the expression of ß-catenin, C-myc, ccndl and fibronectin in the RA rats. CONCLUSION: PPS has significant therapeutic effect on RA model rats through inhibiting canonical Wnt signaling.

[Effect of pulchinenoside on FZD8 expression of adjuvant arthritis rats].

To study the effect of pulchinenoside (PULC) on the Frizzled (FZD) expression of adjuvant arthritis ( AA) rats. AA rats were prepared through the toe injection with complete Freund's adjuvant to culture fibroblast-like synoviocytes (FLS). The effect of the oral administration with PULC on the FZD8 expression was detected by the real time qPCR. The effect of FZD8 knockout on the expressions of IL-1, IL-6, IL-8 were detected by MTT and ELISA. The role of miR-375 in the abnomal expression of FZD8 was detected by the real time qPCR. The results showed signfiicant decrease in the FZD8 expression among AA rats, FLS proliferation ater FZD8 knockout and IL-1, IL-6, IL-8 expressions and notable increase in miR-375 expression after the oral administration with PULC. The up-regulated miR-375 expression can inhibit the FZD8 expression. PULC may inhibit the FZD8 expression by up-regulating the miR-375 expression.

[Flavonoids of Echinps latifolius suppress Wnt signaling in adjuvant arthritis rats].

The role of flavonoids of Echinps latifolius (FELT) in Wnt signaling was investigated in adjuvant arthritis (AA) rats. The therapeutic effects of FELT on AA rats were detected by rat arthritis score and MTT. The effect of FELT gavage treatment on the Wnt signaling key gene ß-catenin, C-myc and cyclin D1 in synovium from AA rats was detected by Real-time qPCR, and the effects of FELT gavage treatment on the upstream negative regulation gene SFRP 1,2,4,5 in synovium from AA rats were detected by Real-time qPCR. The results showed that FELT gavage treatment significantly inhibited arthritis score and MTT values in AA rats, significantly inhibited the expression of the Wnt signaling gene ß-catenin, C-myc and cyclin D1, significantly up-regulated the expression of the up- stream negative regulation gene SFRP 1,2,4. FELT has a better therapeutic effect for AA rats.

[Pulchinenoside control MeCP2 expression in FLS from RA model rats].

The role of pulchinenoside (PULC) in the regulation of MeCP2 expression was investigated in RA model rats. Adjuvant arthritis rats were used as RA model rats, and fibroblast-like synoviocytes (FLS) from the RA model rats were cultured. The effect of 100 mg x kg(-1) PULC gavage treatment on the MeCP2 expression and the effect of MeCP2 siRNA on the expression of SFRP2 and ß-catenin were detected by real time qPCR and Western blotting. The role of PULC in the FLS proliferation was detected by MTT. The results showed that the MeCP2 expression was down-regulated, the SFRP2 expression was up-regulated and the FLS proliferation was inhibited in FLS after therapy. MeCP2 siRNA significantly inhibited the MeCP2 expression, up-regulated the SFRP2 expression and inhibited the ß-catenin expression in FLS from RA model rats. PULC may increase the SFRP2 expression, inhibit the Wnt signaling and inhibit the FLS proliferation in FLS from the RA model rats by inhibiting the MeCP2 expression.

[Effect of pulchinenoside in regulating FLS SFRP2 expression of RA model rats].

OBJECTIVE: To study the effect of pulchinenoside (PULC) in modulating SFRP2 expression in fibroblast-like synoviocytes (FLS) of rheumatoid arthritis (RA) model rats. METHOD: The effect of PULC in treating RA rats was evaluated by rat arthritis score and paw swelling score. The inhibitory effect of PULC on FLS proliferation was detected by MTT reagent. The effects of PULC gavage treatment in modulating gene expression of FLS SFRP2, critical gene beta-catenin of Wnt pathway and downstream effector genes C-myc of of Wnt pathway were detected by RT-PCR and Western blotting. RESULT: PULC had a significant effect in treating RA rats and that SFRP2 expression was down-regulated in FLS. After PULC gavage treatment, FLS SFRP2 expression was obviously up-regulated, whereas beta-catenin and C-myc gene expressions were significantly down-regulated. CONCLUSION: PULC can inhibit abnormal proliferation of synovial membrane by modulating Wnt pathway of RA rats.

In Silico System Pharmacology for the Potential Bioactive Ingredients Contained in Xingnaojing Injection () and Its Material Basis for Sepsis Treatment.

OBJECTIVE: To elucidate the action mechanism of Xingnaojing Injection (, XNJI) for sepsis, and to target screen the potential bioactive ingredients. METHODS: An integrated protocol that combines in silico target screen (molecular docking) and database mapping was employed to find the potential inhibitors from XNJI for the sepsis-related targets and to establish the compound-target (C-T) interaction network. The XNJI's bioactive components database was investigated and the sepsis-associated targets were comprehensively constructed; the 3D structure of adenosine receptor A2a and 5-lipoxygenase proteins were established and evaluated with homology modeling method; system network pharmacology for sepsis treatment was studied between the bioactive ingredients and the sepsis targets using computational biology methods to distinguish inhibitors from non inhibitors for the selected sepsis-related targets and C-T network construction. RESULTS: Multiple bioactive compounds in the XNJI were found to interact with multiple sepsis targets. The 32 bioactive ingredients were generated from XNJI in pharmacological system, and 21 potential targets were predicted to the sepsis disease; the biological activities for some potential inhibitors had been experimentally confirmed, highlighting the reliability of in silico target screen. Further integrated C-T network showed that these bioactive components together probably display synergistic action for sepsis treatment. CONCLUSIONS: The uncovered mechanism may offer a superior insight for understanding the theory of the Chinese herbal medicine for combating sepsis. Moreover, the potential inhibitors for the sepsis-related targets may provide a good source to find new lead compounds against sepsis disease.

miR-375 regulates the canonical Wnt pathway through FZD8 silencing in arthritis synovial fibroblasts.

Whether the rheumatoid arthritis (RA) pathogenesis is regulated by microRNA (miRNA) is not entirely clear. In this study, we found that miR-375 was down-regulated significantly in fibroblast-like synoviocytes (FLS) in adjuvant-induced arthritis (AIA) rat model compared with control. Because the web-based software TargetScan and PicTar predict Frizzled 8 (FZD8) as the target of miR-375, we investigated whether up-regulated miR-375 plays a role in the activation of the canonical Wnt signaling by targeting the FZD8. Furthermore, the purpose of the present experiments was also to determine the role of miR-375 in the pathogenesis of AIA rat model and to ascertain the effects of FZD8 in this process. Real time qPCR, Western blotting, ELISA and ChIP assay were used to assess the inhibited role of miR-375 in the pathogenesis of AIA rat model and the canonical Wnt signaling. RNA interference was also used to detect the role of knockdown of dephosphorylated ß-catenin. Luciferase reporter gene and related methods were performed to determine the FZD8 as the target of miR-375. The increased miR-375 inhibited the pathogenesis of AIA rat model as indicated by decreases in the several disease markers, such as MMP3 and fibronectin. Interestingly, miR-375 also inhibited the canonical Wnt signaling, and the stabilized form of ß-catenin blocked the miR-375 effects. FZD8 was identified as the target of miR-375 in AIA rat model by the firefly luciferase reporter gene. In summary, our results demonstrate that miR-375 regulates the pathogenesis of AIA rat model through the canonical Wnt signaling pathway. This discovery may provide new targets for therapeutic intervention to benefit RA patients.

In silico target fishing for the potential bioactive components contained in Huanglian Jiedu Tang (HLJDD) and elucidating molecular mechanisms for the treatment of sepsis.

The present study was designed to target fish for potential bioactive components contained in a Huang Lian Jie Du decoction (HLJDD) and identify the underlying mechanisms of action for the treatment of sepsis at the molecular level. he bioactive components database of HLJDD was constructed and the sepsis-associated targets were comprehensively investigated. The 3D structures of the PAFR and TXA2R proteins were established using the homology modelling (HM) method, and the molecular effects for sepsis treatment were analysed by comparing the bioactive components database and the sepsis targets using computational biology methods. The results of the screening were validated with biological testing against the human oral epidermal carcinoma cell line KB in vitro. We found that multiple bioactive compounds contained in the HLJDD interacted with multiple targets. We also predicted the promising compound leads for sepsis treatment, and the first 28 compounds were characterized. Several compounds, such as berberine, berberrubine and epiberberine, dose-dependently inhibited PGE2 production in human KB cells, and the effects were similar in the presence or absence of TPA. This study demonstrates a novel approach to identifying natural chemical compounds as new leads for the treatment of sepsis.

Critical roles of microRNAs in the pathogenesis of systemic sclerosis: New advances, challenges and potential directions.

Systemic sclerosis (SSc) is an autoimmune disease characterized by immune disorders, vascular obliteration, excessive extracellular matrix deposition, skin fibrosis, and further pathological change of internal organs. To date, the exact etiology of this complicated disease remains unknown. Over the past few years, the roles of epigenetic modifications caused by environmental factors have been intensively studied in relation to the disease pathogenesis, and important advances have been made. This review focuses on the new advances of microRNAs (miRNAs) in the field of SSc research, including the upstream regulatory factors of miRNAs, the downstream targets, and the feedback mechanisms between miRNAs and their targets. We also discussed the correlation of miRNAs and DNA methylation, the miRNAs and the gene polymorphism. Overall, the findings presented in this review illustrated how miRNAs play important roles in the pathogenesis of SSc. However, several unanswered questions continue to impede our understanding of this complex disease. Future research should focus on the identification of new biomarkers for early diagnosis and prognosis, which will help us improve the clinical treatment of patients with SSc. In addition, we discussed the challenges of miRNA study in SSc in the future. Since the miRNA injection may be a promising therapeutic approach for SSc treatment, one of the challenges in the future is to evaluate the therapeutic effects of miRNA and anti-miRNAs using SSc model animals. In light of the fact that one miRNA can target many mRNAs, and one mRNA is targeted by many miRNAs, the effect of miRNA changes on other gene expression should be investigated to evaluate the treatment safety of miRNA injection in vivo.

MicroRNA-663 activates the canonical Wnt signaling through the adenomatous polyposis coli suppression.

Rheumatoid arthritis (RA) is a symmetrical polyarticular autoimmune disease of unknown etiology. In this present study, we observed that the adenomatous polyposis coli (APC) expression is down-regulated and the expression of microRNA (miR)-663 increased significantly in synovium from RA patients compared with control. Target gene prediction for miR-663 revealed that the mRNA of APC gene, which is a member of the canonical Wnt signaling pathway, has a miR-663 binding site in its 3'-untranslated region (3'UTR). The result showed that increased miR-663 suppressed the APC expression significantly, and this down-regulation of APC expression triggered the activation of canonical Wnt signaling through accumulation of ß-catenin in fibroblast-like synoviocytes (FLS). In addition, increased miR-663 induced the FLS proliferation and the expression MMP3 and fibronectin during disease development. Therefore, miR-663 can be considered as a critical regulator of RA pathogenesis and can be utilized for developing miRNA-based therapeutic agents for RA patients.

DNMT1 activates the canonical Wnt signaling in rheumatoid arthritis model rats via a crucial functional crosstalk between miR-152 and the DNMT1, MeCP2.

In previous study, we identified that microRNA (miR)-152 expression was down-regulated in RA model rats, and overexpression of miR-152 inhibited the canonical Wnt signaling through the DNA methyltransferase (DNMT1) inhibition. However, the exact molecular mechanisms of DNMT1 were unclear. In this work, we investigate whether DNMT1 affects the pathogenesis of RA model rats and targets the miR-152 promoter. The effects of DNMT1 on the canonical Wnt signaling, the pathogenesis of RA model rats and the SFRP1 expression were detected by the real time qPCR, Western blotting, ELISA, MTT and viable cell number assay. The interaction between miR-152 and DNMT1, methyl CpG binding protein 2 (MeCP2) was investigated by real time qPCR and chromatin immunoprecipitation (ChIP). Our results revealed that increased DNMT1 activated the canonical Wnt signaling could not only by targeting SFRP4 may also by SFRP1 in RA model rats. Furthermore, treatment of DNMT1 inhibitor, 5-aza-2'-deoxycytidine (5-azadC), or knockdown of DNMT1, or knockdown of MeCP2 led to increased miR-152 expression by reversion of its promoter hypermethylation, DNMT1 and MeCP2 binding to the CpG islands of miR-152 promoter. Interestingly, it is proved a synergistic inhibition effect of DNMT1 and MeCP2 in this process. Moreover, overexpression of miR-152 could inhibit DNMT1 expression and result in a decrease of DNMT1 and MeCP2 binding to miR-152 promoter, and inhibition of miR-152 expression would reverse it. These observations demonstrate a crucial functional crosstalk between miR-152 and the DNMT1, MeCP2 by a double-negative circuit involved in the pathogenesis of RA model rats.

MicroRNA-152 modulates the canonical Wnt pathway activation by targeting DNA methyltransferase 1 in arthritic rat model.

Rheumatoid arthritis (RA) is an autoimmune and progressive systemic disease of unknown etiology. Research shows that fibroblast-like synoviocytes (FLS) participate in the cartilage erosion, synovial hyperplasia, inflammatory cytokine secretion and suggests that fibroblast-like synoviocytes (FLS) display a crucial role in RA pathogenesis. Recent studies have suggested the role of the Wnt signaling pathway in the pathogenesis of RA. In previous study, we identified that increased methyl-CpG-binding protein 2 (MeCP2) reduced the secreted frizzled-related protein 4 (SFRP4) expression in FLS in Arthritic rat model and the DNA methyltransferase (DNMT) inhibitor 5-Aza-2'-deoxycytidine (5-azadC) could induce the SFRP4 expression, indicating that DNMT has a key role in the differential expression of SFRP4. MicroRNAs (MiRNAs), which are small non-coding RNAs, are involved in diverse biological functions, regulation of gene expression, pathogenesis of autoimmune disease and carcinogenesis. In light of the directly down-regulation of miR-152 on DNMT1 expression by targeting the 3' untranslated regions of its transcript in nickel sulfide (NiS)-transformed human bronchial epithelial cells, we investigated whether miR-152 is aberrantly expressed and targets DNMT1 in FLS in Arthritic rat model. Our results demonstrated that the expression of miR-152 was specifically down-regulated in Arthritic rat model, whereas up-regulation of miR-152 in FLS resulted in a marked reduction of DNMT1 expression. Further experiments revealed that increased miR-152 indirectly up-regulated the SFRP4 expression, a negative regulator of WNT signaling pathway, by targeting the DNMT1. Moreover, activation of miR-152 expression in FLS could inhibit the canonical Wnt pathway activation and result in a significant decrease of FLS proliferation. MiR-152 and DNA methylation may provide molecular mechanisms for the activation of canonical Wnt pathway in RA. Combination of miR-152 and DNMT1 may be a promising treatment strategy for RA patients in which SFRP4 is inactivated.

New advances of DNA methylation and histone modifications in rheumatoid arthritis, with special emphasis on MeCP2.

Epigenetics is a steadily growing research area in many human diseases, especially in autoimmune diseases such as rheumatoid arthritis (RA). RA is an autoimmune disease with unclear etiology characterized by chronic inflammation and joint destruction and fibroblast-like synoviocytes (FLS) display a crucial role in the pathogenesis of RA. Even though the etiology is not yet fully understood, RA is generally considered to be caused by a combination of epigenetic modification, deregulated immunomodulation, and environmental factors. Epigenetic modifications, including DNA methylation and post-translational histone modifications, such as histone methylation and histone (de)acetylation are identified as regulatory mechanisms in controlling aggressive FLS activation in patients and animal models. In the last 3years, the field of epigenetics in RA has impressively increased. Methyl-CpG-binding protein 2 (MeCP2) is first identified as a transcriptional repressor that inhibits gene expression through the interpretation of two epigenetic markers, DNA methylation and histone modification. The cooperative action among MeCP2, DNA methylation and histone modifications indicates that MeCP2 should participate in the pathogenesis of RA through silence of certain gene transcription. In this review, we consider the role of DNA methylation and histone modifications in the development of RA, with a special focus on increased MeCP2 expression in RA animal models.

New advances of microRNAs in the pathogenesis of rheumatoid arthritis, with a focus on the crosstalk between DNA methylation and the microRNA machinery.

Rheumatoid arthritis (RA) is a symmetrical polyarticular disease of unknown aetiology that affects primarily the articular cartilage and bone. Characteristic features of RA pathogenesis are persistent inflammation, synovium hyperplasia and cartilage erosion accompanied by joint swelling and joint destruction. Several lines of evidence have showed a crucial role of activated fibroblast-like synoviocytes (FLS) in the pathogenesis of RA. MicroRNAs (miRNAs) are endogenous, single-stranded, non-coding RNAs with about 21 nucleotides in length and have been detected in a variety of sources, including tissues, serum, and other body fluids, such as saliva. In light of key roles of miRNAs in the regulation of gene expression, miRNAs influence a wide range of physiological and pathological processes. For example, miRNAs are evident in various malignant and nonmalignant diseases, and accumulating evidence also shows that miRNAs have important roles in the pathogenesis of RA. It has been demonstrated that miRNAs can be aberrantly expressed even in the different stages of RA progression, allowing miRNAs to help understand the pathogenesis of the disease, to act as important biomarkers, and to monitor the disease severity and the effects of drug treatment. In addition, miRNAs are emerging as potential targets for new therapeutic strategies of this kind of autoimmune disorders. The ultimate goal is the identification of miRNA targets that could be manipulated through specific therapies, aiming at activation or inhibition of specific miRNAs responsible for the RA development. In this review, the importance of miRNAs in the pathogenesis of RA is discussed systematically, with particular emphasis on the role of the crosstalk between DNA methylation and the microRNA machinery.