Apoptosis Of Synovial Fibroblasts Research Articles

ATF3 Modulates the Proliferation, Migration, and Apoptosis of Synovial Fibroblasts after Arthroscopy by Promoting RGS1 Transcription.

Osteoarthritis (OA) is a degenerative joint disease involving both cartilage and synovium. Activating transcription factor 3 (ATF3) and regulator of G protein signaling 1 (RGS1) have been reported to be up-regulated in OA. However, little is known regarding the relationship between these two genes and the mechanism of this relationship in OA development. Therefore, the present study explores the mechanism of ATF3-mediated RGS1 in the proliferation, migration, and apoptosis of synovial fibroblasts. After the OA cell model was constructed with TGF-β1 induction, human fibroblast-like synoviocytes (HFLSs) were transfected with ATF3 shRNA or RGS1 shRNA alone or co-transfected with ATF3 shRNA and pcDNA3.1-RGS1. Then, proliferation, migration, apoptosis, and the expression of ATF3, RGS1, α-SMA, BCL-2, caspase3, and cleaved-caspase3 were measured. Meanwhile, the potential relationship between ATF3 and RGS1 was predicted and validated. Analysis of the GSE185059 dataset suggested that RGS1 was up-regulated in OA synovial fluid exosomes. Moreover, ATF3 and RGS1 were both highly expressed in TGF-β1-induced HFLSs. Transfection of ATF3 shRNA or RGS1 shRNA significantly reduced proliferation and migration and promoted apoptosis of TGF- β1-induced HFLSs. Mechanistically, ATF3 bound to the RGS1 promoter and elevated RGS1 expression. Silencing ATF3 repressed proliferation and migration and enhanced apoptosis of TGF-β1-induced HFLSs by down-regulating RGS1. ATF3 binds to the RGS1 promoter and enhances RGS1 expression to accelerate cell proliferation and block cell apoptosis in TGF-β1-induced synovial fibroblasts.

Qinteng Tongbi Decoction Medicated Serum Exerts Regulates the Proliferation, Migration, and Apoptosis of Synovial Fibroblasts in Adjuvant-Induced Arthritis Rats Model via Phosphatidylinositol 3-Kinase/Protein Kinase B Signaling Pathway

Background Qinteng Tongbi decoction (QTTBD) was an empirical prescription that could effectively prevent and treat rheumatoid arthritis (RA), but there was no report of pharmacological studies on this prescription. The purpose of this paper was to report the effects of QTTBD on the proliferation, migration, and apoptosis of synovial fibroblasts in adjuvant arthritis model rats, and to reveal its anti-RA regulatory mechanism. Methods To divide the fibroblast-like synovial (FLS) cells of experimental rats into 6 groups (blank control group, model control group, positive drug group, QTTBD high, medium, and low dose groups) and cultured with serum-containing drugs. And using Cell Counting Kit-8 to detect the proliferation rate of FLS cells, flow cytometry to detect the apoptosis of FLS cells, the enzyme-linked immunosorbent assay method to detect the levels of interleukin (IL)-6, IL-1β, and tumor necrosis factor-α (TNF-α), Western Blot to detect phosphatidylinositol 3-kinase (PI3K), AKT1, p-AKT1, Bax and Bcl-2 gene and protein expression. Results Experimental results showed that QTTBD-containing serum could effectively inhibit the proliferation of FLS cells ( p <0 .05), induce the apoptosis of FLS cells, reduce the expression levels of inflammatory factors such as IL-6, IL-1β, and TNF-α ( p <0 .05), reduce expression of PI3K, AKT1, p-AKT1, and Bax ( p <0 .05), while the Bcl-2 expression increased ( p <0 .05). Conclusion QTTBD could effectively regulate the proliferation, migration, and apoptosis of FLS cells in adjuvant-induced arthritis (AIA) rats, and its mechanism might be related to regulating the level of inflammatory factors and intervening in the PI3K/protein kinase B (AKT) signaling pathway.

Comprehensive evaluation and anti-inflammatory activity of “Zhi” polygonatum cyrtonema produced by the classical steaming approach

IntroductionPolygonati Rhizoma, known as “Huangjing”, was first documented in the well-known book Mingyi Bielu, written in the Chinese Han Dynasty. A "Nine-Steam-Nine-Bask" method is the best way to increase their tonic function by steaming and drying the raw rhizomes. This study was conducted with the primary objective of assessing "Zhi" P. cyrtonema qualitatively and quantitatively. Additionally, in vitro studies of the anti-inflammatory activity of "Zhi" P. cyrtonema revealed its pharmacodynamic effects and possible mechanisms of action. MethodsP. cyrtonema was steamed and dried nine times and subsequently subjected to hot water extraction and ethanol precipitation to obtain the desired P. cyrtonema polysaccharides (PCPs). Several approaches, including HPGPC-RID, NMR, and GC-MS, were used to evaluate the molecular weight, composition changes, and monosaccharide composition of PCPs during steaming. Multivariate data analysis, including PCA and HCA, was applied for the divergence analysis of "Zhi" P. cyrtonema. The anti-inflammatory effect of 4-Z PCPs on MH7A cells was evaluated using a cell viability assay. ELISA assays, DAPI staining, cell cycle assay, and scratching experiments revealed the potential mechanism. ResultsWith increasing steaming time, the color of the herb gradually changes from yellow to black and finally to dark black. In processed roots, the levels of polysaccharides decreased, while monosaccharides, such as galactose and glucose, increased. The high-molecular-weight polysaccharide was partially hydrolyzed, forming smaller polysaccharides, monosaccharides, and trace oligosaccharides. In the HPGPC profile, peak 1, with a retention time of 5.20 min and a molecular mass of 1140.51 kDa, can transform into peak 2 (6.10 min, 374.00 kDa) and peak 3 (9.71 min, 9.73 kDa). Using NMR analysis, it has been shown that 5-hydroxymethylfurfural (5-HMF), a toxic substance formed by the thermal degradation of saccharides, is present from the start of the fifth processed herb but is rare before 5-Z P. cyrtonema. The GC-MS analysis also revealed the presence of various monosaccharides, including mannose, galactose, glucose, fructose, rhamnose, arabinose, and galacturonic acid in "Zhi" P. cyrtonema. Using saccharides as variables, we were able to classify "Zhi" P. cyrtonema into four groups: fresh and 1-Z PCPs in groups A, 2-Z, 3-Z, 4-Z, 5-Z, 6-Z, 7-Z and 8-Z PCPs in group C, and 9-Z PCPs in group D. Results of the MH7A cell experiment indicate that 4-Z PCPs are more efficient than 0-Z and 9-Z PCP. After the fourth processing cycle, the differences between metabolic profiles became smaller. ConclusionsA combination of UV–Vis spectra, HPGPC-RID analysis, and NMR techniques were used in this study to achieve qualitative and quantitative analyses of "Zhi" PCPs, and we were able to make a comprehensive evaluation of "Zhi" P. cyrtonema. Meanwhile, using saccharides as variables by the HCA and PCA method, we were able to divide "Zhi" P. cyrtonema into four groups, namely fresh and 1-Z PCPs as group A, and 2-Z, 3-Z and 4-Z PCPs as group B, as well as 5-Z, 6-Z, 7-Z, 8-Z as group C, and 9-Z PCPs as group D. The anti-inflammatory activity studies indicated that the 4-Z PCPs better inhibited the growth of MH7A cells and induced apoptosis of synovial fibroblasts, suggesting that the 4-Z PCPs could be used as an anti-inflammatory reagent.

Wenhua Juanbi Recipe Attenuates Rheumatoid Arthritis via Inhibiting miRNA-146a-Mediated Autophagy.

Wenhua Juanbi Recipe (WJR) is widely used for the treatment of rheumatoid arthritis (RA) in China. However, its mechanism of action remains unclear. This study was designed to investigate the potential therapeutic effects of WJR on the proliferation and apoptosis of synovial fibroblasts in RA and its efficacy in inhibiting miRNA-146a-mediated cellular autophagy. A collagen-induced arthritis (CIA) Wistar rat model was established. The model rats were administered WJR or methotrexate (MTX) to assess the therapeutic effect of the drugs. The chemical components of WJR were analyzed using UPLC-Q/TOF-MS. Histological changes; miRNA-146a, ATG5, ATG7, ATG12, Beclin1, LC3II, Bax, and Bcl2 expression; synovial apoptosis; and cellular proliferation were assessed. Primary synovial fibroblasts (FLS) were cultured in vitro using tissue block and transfected with miRNA-146a; an autophagy inducer was added to FLS, inhibiting the PI3K/AKT/mTOR pathway. FLS were cocultured with WJR-containing serum to observe the effects of miRNA-146a-mediated autophagy via the PI3K/AKT/mTOR pathway on CIA-affected rats. Forty and thirty-one compounds were identified in WJR in the positive and negative ion modes, respectively. WJR significantly reduced toe swelling, arthritis scores, and expression of miRNA-146a and autophagy genes (ATG5, ATG7, ATG12, Beclin1, LC32, and Bcl2). Moreover, Bax expression, apoptosis, and attenuated proliferation were observed in rats. WJR could, therefore, regulate autophagy by influencing the miRNA-146a-mediated PI3K/AKT/mTOR pathway, which induces apoptosis and proliferation of FLS. WJR can inhibit autophagy, apoptosis, and proliferation in a CIA rat model by inhibiting the miRNA-146a-mediated PI3K/AKT/mTOR pathway.

Xinfeng Capsules promotes apoptosis of synovial fibroblasts and attenuates inflammation in rheumatoid arthritis by regulating lncRNA MAPKAPK5-AS1

To explore the regulatory effects of Xinfeng Capsules(XFC) on the apoptosis of synovial fibroblasts(FLS) and inflammation in rheumatoid arthritis(RA) via lncRNA MAPKAPK5-AS1(MK5-AS1). Thirty healthy people and 30 patients with RA due to spleen deficiency and dampness exuberance were collected for extracting the peripheral blood mononuclear cells(PBMCs) before and after XFC treatment, which were used to observe the correlation between MK5-AS1 and clinical indicators as well as MK5-AS1 expression before and after XFC treatment. Following the establishment of RA-FLS cell line and the preparation of XFC-containing serum, MK5-AS1-overexpression plasmid was constructed and transfected into RA-FLS for investigating the efficacy of XFC-containing serum in regulating inflammation and apoptosis of RA-FLS via MK5-AS1. The expression of MK5-AS1 in PBMCs of patients with RA due to spleen deficiency and dampness exuberance was decreased(P<0.001). The ROC curve analysis revealed the AUC of 83.9%. Correlation analysis showed that MK5-AS1 was negatively correlated with ESR, CRP, RF, CCP, and spleen deficiency and dampness exuberance syndrome score. The expression of MK5-AS1 increased significantly after XFC treatment(P<0.001). As demonstrated by association analysis, XFC decreased MK5-AS1, ESR, CRP, RF, and spleen deficiency and dampness exuberance syndrome score, with the degree of support all greater than 83%, confidence greater than 80%, and lift greater than 1. The results of RT-qPCR showed that the MK5-AS1 RNA expression significantly decreased after TNF-α stimulation(P<0.01), which, however, increased significantly after the intervention with XFC-containing serum(P<0.05). Such expression rose again after the transfection of pcDNA3.1-MK5-AS1(P<0.01). ELISA results showed that TNF-α stimulation elevated the expression of pro-inflammatory factor IL-17 but lowered the expression of anti-inflammatory factor IL-4(P<0.01). After intervention with XFC-containing serum, the expression of IL-17 decreased while that of IL-4 increased(P<0.01). The transfection of pcDNA3.1-MK5-AS1 contributed to the reduction in IL-17 expression but the elevation in IL-4 expression(P<0.01). The immunofluorescence(IF) findings demonstrated that the expression of pro-apoptotic protein Bax was down-regulated, whereas that of the anti-apoptotic protein Bcl-2 was up-regulated after TNF-α stimulation(P<0.01). After the intervention with XFC-containing serum, the Bax expression was increased, while Bcl-2 expression was decreased(P<0.01), which were remarkably collaborated by the transfection of pcDNA3.1-MK5-AS1(P<0.05). The expression of MK5-AS1 is significantly decreased in both RA-PBMCs and RA-FLS, implying that XFC inhibits inflammatory reaction and promotes the apoptosis in RA by regulating the expression of MK5-AS1.

MicroRNA-449 targets histone deacetylase 1 to regulate the proliferation, invasion, and apoptosis of synovial fibroblasts in rheumatoid arthritis.

Rheumatoid arthritis (RA) is a chronic joint disease. The study aimed to explore the effects of microRNA (miR)-449 and histone deacetylase 1 (HDAC1) on the proliferation, invasion, and apoptosis of synovial fibroblasts in rheumatoid arthritis. Synovial tissue was collected from 20 patients with RA and 20 patients with osteoarthritis (OA) who underwent joint replacement surgery. RA synovial fibroblasts (RASFs) and OA synovial fibroblasts (OASFs) were isolated and cultured. Real-time quantitative PCR was used to detect the expression levels of miR-449 and HDAC1 in synovial tissues and cells. Western blot was performed to detect the cellular expression levels of HDAC1 protein, and apoptosis and invasion-related proteins. The proliferation, invasion, and apoptosis of RASFs were detected by MTT assay, Transwell assay, and flow cytometry. The dual-luciferase reporter gene was used to test the targeting relationship between inflammatory miR-449 and HDAC1. Compared with normal synovial tissue and OASFs, the levels of HDAC1 messenger RNA in RA synovial tissue and RASF cells were significantly increased (P<0.01), while the expression levels of miR-449 were significantly decreased (P<0.01). The dual-luciferase reporter gene experiment confirmed that miR-449 could specifically bind to the 3' untranslated region of HDAC1 to inhibit its luciferase activity (P<0.05). HDAC1 inhibition or miR-449 overexpression significantly inhibited the proliferation and invasion of RASFs (P<0.001), while inducing their apoptosis (P<0.001). HDAC1 overexpression reversed the biological effects of miR-449 on RASFs (P<0.001). miR-449 inhibits the proliferation and invasion of RASFs and induces their apoptosis by targeting HDAC1, thereby exerting a protective effect against RA.

MiR-140-3p inhibits the cell viability and promotes apoptosis of synovial fibroblasts in rheumatoid arthritis through targeting sirtuin 3

BackgroundSynovial fibroblasts (SFs) with the abnormal expressions of miRNAs are the key regulator in rheumatoid arthritis (RA). Low-expressed miR-140-3p was found in RA tissues. Therefore, we attempted to investigate the effect of miR-140-3p on SFs of RA.MethodsRA and normal synovial fibrous tissue were gathered. The targets of miR-140-3p were found by bioinformatics and luciferase analysis. Correlation between the expressions of miR-140-3p with sirtuin 3 (SIRT3) was analyzed by Pearson correlation analysis. After transfection, cell viability and apoptosis were detected by cell counting kit-8 and flow cytometry. The expressions of miR-140-3p, SIRT3, Ki67, Bcl-2, Bax, and cleaved Caspase-3 were detected by RT-qPCR or western blot.ResultsLow expression of miR-140-3p and high expression of SIRT3 were found in RA synovial fibrous tissues. SIRT3 was a target of miR-140-3p. SIRT3 expression was negatively correlated to the expression of miR-140-3p. MiR-140-3p mimic inhibited the MH7A cell viability and the expressions of SIRT3, Ki67, and Bcl-2 and promoted the cell apoptosis and the expressions of Bax and cleaved Caspase-3; miR-140-3p inhibitor showed an opposite effect to miR-140-3p mimic on MH7A cells. SIRT3 overexpression not only promoted the cell viability and inhibited cell apoptosis of MH7A cells but also reversed the effect of miR-140-3p mimic had on MH7A cells.ConclusionsThe results in this study revealed that miR-140-3p could inhibit cell viability and promote apoptosis of SFs in RA through targeting SIRT3.

Chemical variability of Rhododendron tomentosum (Ledum palustre) essential oils and their pro-apoptotic effect on lymphocytes and rheumatoid arthritis synoviocytes

Rhododendron tomentosum (Ledum palustre) is an aromatic plant traditionally used for alleviating rheumatic complaints which makes it a potential candidate for a natural drug in rheumatoid arthritis (RA) treatment. However, the effects of plants’ volatiles on apoptosis of synovial fibroblasts and infiltrating leucocytes of RA synovia, have not been reported. Volatile fraction of R. tomentosum is chemically variable and chemotypes of the plants need to be defined if the oil is to be used for therapeutic purposes. In the presented work, cluster analysis of literature data enabled to define 10 chemotypes of the plant. The volatile fractions of known composition were then tested for bioactivity using a RA-specific in vitro models. Essential oils of two wild types (γ-terpineol and palustrol/ledol type) and one in vitro chemotype (ledene oxide type) were obtained by hydrodistillation and their bioactivity was tested in two in vitro models: I - peripheral blood lymphocytes of healthy volunteers and II - synoviocytes and immune cells isolated from synovia of RA patients. The influence of oils on blood lymphocytes’ proliferation and apoptosis rates of synovia-derived cells was determined by flow cytometry. Dose-dependent inhibitory effect of the serial dilutions of R. tomentosum oils on proliferation rates of blood lymphocytes was found. At 1:400 dilutions, all the tested oils increased the number of necrotic cells in synovial fibroblasts from RA synovia. Additionally, increased proportions of late apoptotic cells were observed in leucocyte populations subjected to oils at 1:400 dilution.

MicroRNA-mediated GAS1 downregulation promotes the proliferation of synovial fibroblasts by PI3K-Akt signaling in osteoarthritis.

Hyperplastic synovial fibroblasts (SFs) serve a critical role in the pathogenesis of knee osteoarthritis (OA); however, the molecular mechanism involved in OA during synovial tissue hyperproliferation remains unclear. Growth arrest-specific gene 1 (GAS1), a cell growth repressor gene, was found to be downregulated in OASFs according to previous preliminary experiments. It was therefore hypothesized that reduced GAS1 expression may participate in the hyperproliferation of SFs in OA development, downstream of possible microRNA (miR) regulation, in hyperplastic OASFs. In the present study, GAS1 expression was indeed decreased in OASFs and interleukin-1β-induced SFs by reverse transcription-quantitative PCR and western blot analysis. Further cell viability assays, cell cycle and apoptosis analyses revealed that the overexpression of GAS1 can inhibited proliferation, induced cell cycle arrest and promoted apoptosis in SFs. In contrast, GAS1 knockdown in SFs accelerated cell proliferation, enhanced cell cycle progression and suppressed apoptosis. Notably, the suppressive effects of GAS1 were mediated through the inactivation of the PI3K-Akt pathway. Finally, miR-34a-5p and miR-181a-5p were predicted and subsequently verified to directly target the 3′-untranslated region of the GAS1 gene, downregulating GAS1 levels in OASFs and IL-1β-induced SFs. In conclusion, the present study demonstrated that downregulation of GAS1 can lead to the hyperproliferation of SFs in OA pathogenesis through the PI3K-Akt pathway, and miR-34a-5p and miR-181a-5p are potential regulators of GAS1 expression in OA. Therefore, it may be promising to investigate the potential of GAS1 as a novel therapeutic target for preventing SF hyperplasia in OA.

Guizhi-Shaoyao-Zhimu decoction possesses anti-arthritic effects on type II collagen-induced arthritis in rats via suppression of inflammatory reactions, inhibition of invasion & migration and induction of apoptosis in synovial fibroblasts

BackgroundRheumatoid arthritis (RA) is a known intractable chronic inflammatory disease of synovial joints characterized by hyperplasia and consecutive inflammation with a high prevalence.Guizhi-Shaoyao-Zhimu (GSZD) is the first choice for clinical treatment of RA in Chinese traditional medicine. This study is aimed to explore the possible pharmacological mechanisms of anti-arthritic effect of GSZD. MethodsType II collagen-induced arthritis (CIA) rat model was used to study the anti-arthritic activity of GSZDin vivo, and toe swelling & arthritis score, serum levels of cytokines, and pathological examinations were carried out. In vitro, TNF-α induced MH7A cells were used to study the possible mechanisms of GSZD. The anti-proliferative effects of GSZD were determined by MMT assay, and pro-apoptotic activity of GSZD in MH7A cells was determined by flow cytometry analysis & DAPI staining. Furthermore, the adhesive and invasive abilities of MH7A cells were determined using cell adhesion and transwell assays. MMPs levels were determined by ELISA assays, and mRNA expressions of Caspase-3, -9, Bax, SOCS1, Bcl-2, JAK2, STAT-3 and -5 were determined using qRT-PCR analysis. Besides, the major chemical components in GSZD were analyzed by HPLC-QqQ-MS analysis. ResultsOur results showed GSZD reduced the toe swelling & arthritis score, and serum levels of TNF-α, IL-1β, IL-6 & IL-17a in CIA rats; pathological examination results indicated GSZD improved ankle joint injury in CIA rats.In vitro, GSZD showed significant anti-proliferative and pro-apoptotic effects on TNF-α stimulated MH7A cells. After GSZD treatment, the adhesive and invasive abilities of MH7A cells were reduced, and secretions of MMPs, IL-6 and IL-8 were also reduced. GSZD decreased the releases of TNF-α and IL-1β in LPS stimulated RAW 264.7 cells. Further studies showed GSZD up-regulated mRNA expressions of Caspase-3, -9, Bax, and SOCS1, whereas down-regulated mRNA expressions of Bcl-2, JAK2, STAT3 and STAT5. Besides, 13 major chemical components were identified in GSZD extracts through HPLC-QqQ-MS analysis. ConclusionOur results suggested GSZD possesses an anti-rheumatic effect on CIA rats, and the possible mechanism is related to inhibiting inflammatory response, inhibiting invasion and migration of synovial fibroblasts, and inducing apoptosis in synovial fibroblasts.

Expression and function of miR-155 in rat synovial fibroblast model of rheumatoid arthritis.

Rheumatoid arthritis (RA) is a common autoimmune disease characterized by joint synovial inflammation and is a challenge for researchers and clinicians. MicroRNAs (miRNAs/miRs) represent a group of small non-coding RNA molecules that post-transcriptionally regulate mRNA expression and are involved in various diseases, including cancer, autoimmune and metabolic diseases, as well as neurological disorders. In the present study, various experiments were performed to investigate the effects and underlying mechanism of miR-155 in RA using rat synoviocytes induced by lipopolysaccharide (LPS) to model rheumatoid arthritis. It was revealed that synovial fibroblasts exhibited significantly higher miR-155 mRNA levels than the control group. Compared with the RA group, the viability of synovial fibroblasts was significantly decreased in the miR-155 mimics + RA group, but markedly increased in the miR-155 inhibitor + RA group. Compared with that in the RA + NC mimic or RA + NC inhibitor groups, the apoptosis of synovial fibroblasts increased significantly in the miR-155 mimics + RA group, but was significantly decreased in the miR-155 inhibitor + RA group. The miR-155 mimics + RA group exhibited higher expression levels of β-catenin, matrix metalloproteinase 7 and cyclin D1 compared with the miR-155 inhibitor + RA group, and the glycogen synthase kinase protein levels was lower compared with the miR-155 inhibitor + RA group. In brief, it was inferred that the Wnt signaling pathway is involved in the miR-155-associated inhibition of RA synovial fibroblast viability and induction of cell apoptosis. Inhibition of miR-155 may be an effective treatment for RA through regulation of the Wnt signaling pathway to reduce cell apoptosis and enhance cell viability.

IL-35 ameliorates collagen-induced arthritis by promoting TNF-α-induced apoptosis of synovial fibroblasts and stimulating M2 macrophages polarization.

Synovitis, the chronic inflammation of the synovial membranes, is a hallmark of rheumatoid arthritis, a chronic disease with profound impact on human health. Recently, interleukin-35 (IL-35), a new member of the IL-12 family, was identified as an anti-inflammatory and immunosuppressive cytokine and was shown to ameliorate collagen-induced arthritis (CIA) in mice. However, the mechanism by which IL-35 alleviates CIA remains unknown. In this study, we investigated the effect of IL-35 on the CIA microenvironment and, specifically, the tumor necrosis factor alpha (TNF-α)-induced macrophage inflammatory response and apoptosis of fibroblast-like synoviocytes (FLSs). Firstly, using RT-PCR, western blot, and flow cytometry, we found that IL-35 suppressed TNF-α-induced inflammatory responses by down-regulating iNOS and COX-2 in peripheral blood monocyte-derived macrophages. IL-35 also activated alternative M2 macrophage polarization, as determined by evaluation of CCR7 and CD206 expression. Moreover, we showed that IL-35 enhanced TNF-α-induced FLS apoptosis. Using a panel of immunohistochemical and immunofluorescence analyses in a CIA model established in 18 DBA/1J mice, we demonstrated that IL-35 promotes synoviocyte apoptosis and alternative activation of macrophages to alleviate arthritis in vivo. Taken together, our results show that IL-35 promotes TNF-α-induced FLS apoptosis and modulates M2 macrophage polarization to ameliorate CIA inflammation both in vitro and in vivo.

Circadian rhythms and rheumatoid arthritis.

Circadian rhythms (Nobel prize for Medicine 2017) regulate, under action of biological clocks located both at the level of central nervous system and inside peripheral cells, several daily activities, embracing sleep, feeding times, energy metabolism, endocrine and immune functions with related pathological conditions, including rheumatoid arthritis (RA). In RA the circadian rhythms impact on cellular functions, involving night synthesis and release of pro-inflammatory cytokines and chemokines, cell migration to inflamed tissues, phagocytosis, proliferative cell response and all are peaking at late night. In chronic inflammatory conditions such as RA, the amplitude of the circadian rhythm of the anti-inflammatory endogenous cortisol availability is not increased as expected and requested, which indicate a reduced night cortisol secretion under the adrenal chronic stress induced by the disease. Therefore, the prevention/treatment of the immune cell night hyperactivity, with related flare of cytokine synthesis and morning RA clinical symptoms, has been shown more effective when the availability of the exogenous glucocorticoids is obtained in the middle of the night (night release). The impressive positive results observed in RA patients treated with modified-night release prednisone with a low-dose chronotherapy, seem applicable even for other agents such as conventional NSAIDs and DMARDs, including the positive experimental and clinical results obtained by the night time daily administration of methotrexate. Interestingly, a very recent study showed that methotrexate upregulates important cell circadian genes, resulting in induction of apoptosis in synovial fibroblasts. The link between the circadian rhythms of the disease and the chronotherapy of RA is promising.

Endogenous Galectin-9 Suppresses Apoptosis in Human Rheumatoid Arthritis Synovial Fibroblasts

Galectin-9 (Gal9) has been postulated to have anti-inflammatory properties based on the ability of exogenous Gal9 to induce apoptosis in synovial fibroblasts in animal models of rheumatoid arthritis (RA). Here we aimed to assess the potential role of endogenous Galectins, including Gal9, in the inflammatory pathology of the RA synovium in humans. Firstly expression of Galectins 1–9 was determined in synovial fibroblasts (RASF) and dermal fibroblasts (DF) isolated from RA patients, the latter representing a non-inflamed site. We then further challenged the cells with pro-inflammatory TLR agonists and cytokines and assessed Galectin expression. Gal9 was found to be differentially and abundantly expressed in RASF compared to DF. Agonists of TLR3 and TLR4, along with IFNgamma were also found to induce Gal9 expression in RASF. siRNA was then used to knock-down Gal9 expression in RASF and the effects of this on apoptosis and cell viability were assessed. Increased apoptosis was observed in RASF following Gal9 knock-down. We conclude that, unlike exogenous Gal9, endogenous Gal9 is protective against apoptosis and enhances synovial fibroblast viability suggesting that its role in RA is both pathogenic and pro-inflammatory.

TLR3 Ligand Poly(I:C) Exerts Distinct Actions in Synovial Fibroblasts When Delivered by Extracellular Vesicles.

Extracellular vesicles (EV) can modulate the responses of cells to toll-like receptor (TLR) ligation; conversely, TLR ligands such as double-stranded RNA (dsRNA) can enhance the release of EV and influence of the composition and functions of EV cargos. Inflamed synovial joints in rheumatoid arthritis (RA) are rich in EV and extracellular RNA; besides, RNA released from necrotic synovial fluid cells can activate the TLR3 signaling in synovial fibroblasts (SFs) from patients with RA. Since EV occur prominently in synovial joints in RA and may contribute to the pathogenesis, we questioned whether EV can interact with dsRNA, a TLR3 ligand, and modify its actions in arthritis. We have used as model the effects on RA SFs, of EV released from monocyte U937 cells and peripheral blood mononuclear cells upon stimulation with Poly(I:C), a synthetic analog of dsRNA. We show that EV released from unstimulated cells and Poly(I:C)-stimulated U937 cells [Poly(I:C) EV] differ in size but bind similar amounts of Annexin V and express comparable levels of MAC-1, the receptor for dsRNA, on the vesicular membranes. Specifically, Poly(I:C) EV contain or associate with Poly(I:C) and at least partially protect Poly(I:C) from RNAse III degradation. Poly(I:C) EV shuttle Poly(I:C) to SFs and reproduce the proinflammatory and antiviral gene responses of SFs to direct stimulation with Poly(I:C). Poly(I:C) EV, however, halt the death receptor-induced apoptosis in SFs, thereby inverting the proapoptotic nature of Poly(I:C). These prosurvival effects sharply contrast with the high toxicity of cationic liposome-delivered Poly(I:C) and may reflect the route of Poly(I:C) delivery via EV or the fine-tuning of Poly(I:C) actions by molecular cargo in EV. The demonstration that EV may safeguard extracellular dsRNA and allow dsRNA to exert antiapoptotic effects on SFs highlights the potential of EV to amplify the pathogenicity of dsRNA in arthritis beyond inflammation (by concurrently enhancing the expansion of the invasive synovial stroma).

P53-derived hybrid peptides induce apoptosis of synovial fibroblasts in the rheumatoid joint.

Loss of p53-mediated suppression by its dominant-negative counterpart is commonly observed in human cancers, and activating p73 is a therapeutic strategy in p53-mutated oncological patients. In synovial fibroblasts (SFs) from rheumatoid arthritis (RA), mutant p53 can lead to the transformation-like features with resistance to the apoptosis induction. We examined whether intra-articular (i.a.) administration of p53-derived hybrid peptides to activate p73 can induce apoptosis of SFs by using adenoviral vectors encoding 37 amino acid (Ad37AA), a p53-derived hybrid peptide capable of activating p73, to transduce SFs in vitro and inject collagen-induced arthritis (CIA) joints in vivo. Increased p73 expression was found in synovial lining layers and SFs of RA patients and CIA rats. Higher expression of p53 up-regulated modulator of apoptosis (PUMA) and Bax with enhanced apoptosis were found in Ad37AA-transduced SFs, and silencing p73 abrogated the up-regulation of PUMA and Bax. Articular indexes and histologic scores were reduced in Ad37AA-injected joints with decreased SF densities, increased apoptotic cell numbers, and higher PUMA expression levels. We demonstrate that i.a. administration of p53-derived hybrid peptides can activate p73 to induce apoptosis of SFs and ameliorate the rheumatoid joint, implicating an enhancement of the p73-dependent apoptotic mechanism as a pharmacological strategy in the RA therapy.

Inhibitory effect of recombinant human endostatin on the proliferation of hypertrophic scar fibroblasts in a rabbit ear model

Hypertrophic scar (HS) is a pathological scar that particularly occurs after traumatic injuries, surgical procedures and burning. Abnormal activation of hypertrophic scar fibroblasts (HSFs) intensifies fibrosis during wound healing. Our previous studies demonstrated that recombinant human endostatin (rhEndostatin) prevented synovial thickening in adjuvant arthritis (AA) rats via inhibition of proliferation and enhancement of apoptosis in synovial fibroblasts. However, the effect of this protein on HSF proliferation is not known. This study investigated the inhibitory effect of rhEndostatin on the proliferation of cultured HSFs in a rabbit ear model. MTT assay and flow cytometric detection were performed to investigate HSF proliferation and cell cycle progression, respectively. The expression levels of p53, p21, cyclinD1, cyclin-dependent kinase 4 (CDK4) and proliferating cell nuclear antigen (PCNA) in HSFs were detected using real-time PCR and Western blotting. Our data revealed that HSFs treated with rhEndostatin were significantly inhibited in a concentration-dependent manner with an IC50 value of 100mg/L. Also, rhEndostatin (100mg/L) primarily induced G0/G1 and partially G2/M cell cycle arrest of HSFs. There were significant decreases in the expression levels of p53, p27, CDK4, cyclinD1 and PCNA in HSFs treated with rhEndostatin. In conclusion, rhEndostatin inhibited HSF proliferation via G0/G1 and/or G2/M phase arrest of the cell cycle, which was partially due to the down-regulation of cyclinD1, CDK4 and PCNA. These findings suggest that rhEndostatin may reduce scar hypertrophy in vivo via inhibition of HSF proliferation and may be a novel agent for HS treatment.

Endogenous myeloperoxidase is a mediator of joint inflammation and damage in experimental arthritis.

Myeloperoxidase (MPO) is implicated as a local mediator of tissue damage when released extracellularly in many chronic inflammatory diseases. The purpose of this study was to explore the role of endogenous MPO in experimental rheumatoid arthritis (RA). K/BxN serum-transfer arthritis was induced in C57BL/6 wild-type (WT) and MPO knockout (MPO(-/-) ) mice, and disease development was assessed. MPO activity was measured in joint tissues from mice with or without K/BxN arthritis. Collagen-induced arthritis (CIA) was induced in WT and MPO(-/-) mice, and disease development and immune responses were examined. MPO expression was assessed in synovial biopsy samples from patients with active RA, and the effect of MPO on synovial fibroblasts was tested in vitro. MPO was up-regulated in the joints of mice with K/BxN arthritis, and MPO deficiency attenuated the severity of the disease without affecting circulating cytokine levels. In CIA, MPO(-/-) mice had enhanced CD4+ T cell responses and reduced frequency of regulatory T cells in the lymph nodes and spleen, as well as augmented interleukin-17A and diminished interferon-γ secretion by collagen-stimulated splenocytes, without an effect on circulating anticollagen antibody levels. Despite enhanced adaptive immunity in secondary lymphoid organs, CIA development was attenuated in MPO(-/-) mice. Intracellular and extracellular MPO was detected in the synovium of patients with active RA, and human MPO enhanced the proliferation and decreased the apoptosis of synovial fibroblasts in vitro. MPO contributes to the development of arthritis despite suppressing adaptive immunity in secondary lymphoid organs. This suggests distinct effects of local MPO on arthritogenic effector responses.

Efficacy of concurrent administration of cilostazol and methotrexate in rheumatoid arthritis: Pharmacologic and clinical significance

AimsThis study aimed to assess the beneficial effects of the concurrent administration of cilostazol and methotrexate (MTX) on the synovial fibroblasts obtained from patients with rheumatoid arthritis (RA), and in a mouse model of collagen-induced arthritis (CIA). Main methodsProduction of TNF-α, IL-1β, IL-6 and MCP-1 on synovial fibroblasts from RA patients was determined by RT-PCR. Cell proliferation, viability and apoptosis were measured. Anti-arthritic effects were evaluated in CIA mice. Key findingConcurrent use of cilostazol and MTX effectively suppressed proliferation and cell viability associated with enhanced apoptosis of synovial fibroblasts and significantly suppressed cytokine production, including TNF-α, IL-1β, IL-6, and MCP-1 in an additive manner. In line with these findings, LPS-induced increased expression of NURR1 mRNA and protein were suppressed by cilostazol and MTX in accordance with suppression of NF-κB p65 activity. These suppressed effects were reversed by KT5720 (cAMP-protein kinase inhibitor) and ZM 241385 (A2A receptor antagonist), respectively. In CIA mice, treatment with cilostazol, MTX and their combination significantly decreased clinical signs with improvement of histopathological status in the paw of mice, accompanied by reduced serum cytokine levels. Likewise, following concurrent administration, CD68 (+)-cell recruitment, proteoglycan depletion and osteoclast formation were significantly suppressed in association with repressed RANKL expression in the joints of CIA mice. SignificanceIn conclusion, a combination of cilostazol and MTX may provide an effective therapeutic strategy for the suppression of inflammation and the prevention of joint damage in RA via activation of the cAMP-dependent protein kinase in the synovial fibroblasts.

Potential role of S100A4 in an immune response of rheumatoid arthritis

BackgroundRheumatoid arthritis (RA) is characterised by systemic and local inflammation caused by enhanced activity of immune cells producing several inflammatory mediators. S100A4 is a protein with metastasis-promoting functions that is...