The clock gene Bmal1 controls inflammatory mediators in rheumatoid arthritis fibroblast-like synoviocytes.

OBJECT: To clarify the involvement of clock genes in the production of inflammatory mediators from RA-FLS, we examined the role of Bmal1, one of the master clock genes. METHODS: RA-FLSs were stimulated with IL-1ß (0, 20 ng/mL), IL-6 (0, 20 ng/mL), IL-17 (0, 20 ng/mL), TNF-α (0, 20 ng/mL) or IFN-γ (0, 20 ng/mL) to examine the expression of Bmal1, MMP-3, CCL2, IL-6, IL-7 and IL-15 by qPCR and immunofluorescence staining. After silencing Bmal1, RA-FLSs were stimulated with IL-1ß (0, 20 ng/mL), TNF-α (0, 20 ng/mL) or IFN-γ (0, 20 ng/mL) to examine the expressions of inflammatory mediators; MMP-3, CCL2, IL-6 and IL-15 by qPCR, ELISA and immunofluorescence staining. RESULTS: Bmal1 expressions were increased by IL-1ß, TNF-α and IFN-γ stimulations. Under stimulations with TNF-α, IL-1ß, and IFN-γ, mRNA and protein expressions of MMP-3, CCL2 and IL-6 were suppressed by siBmal1. CONCLUSION: Results indicate that Bmal1 contributes the production of MMP-3, CCL2, and IL-6 from RA-FLS, implying Bmal1 is involved in the pathogenesis of RA by regulating the inflammation.

Tocilizumab suppresses NF-kappa B activation via toll-like receptor 9 signaling by reducing cell-free DNA in rheumatoid arthritis.

Endogenous DNA is released into the bloodstream as cell-free DNA (cfDNA) following cell death and is associated with various pathological conditions. However, their association with therapeutic drugs against rheumatoid arthritis (RA) remains unknown. Therefore, we investigated the significance of cfDNA in RA treated with tocilizumab and tumour necrosis factor inhibitor (TNF-I). Biological DMARDs (bDMARDs), including tocilizumab and TNF-I, were administered to 77 and 59 RA patients, respectively. Plasma cfDNA levels were measured at weeks 0, 4, and 12 by quantitative polymerase chain reaction. Disease activity was evaluated at the same time point using DAS28ESR. cfDNA levels from RA synovial cells treated with tocilizumab or etanercept for 24 h were measured. Human toll-like receptor 9 (hTLR9)-expressing HEK293 cells, which release secreted embryonic alkaline phosphatase (SEAP) upon NF-κB activation, were stimulated by cfDNA from RA patients, and subsequently, SEAP levels were determined. NF-κB translocation was evaluated by immunofluorescence staining with or without tocilizumab. The DAS28ESR significantly improved in both bDMARD groups at week 12. However, plasma cfDNA levels significantly decreased in the tocilizumab group at week 12 compared to that in week 0. cfDNA levels correlated with DAS28ESR in biological treatment-naïve patients administered tocilizumab. cfDNA levels in synovial cells were significantly suppressed by tocilizumab treatment and unaltered with etanercept. HEK293 cells released SEAP upon cfDNA stimulation, and the observed NF-κB nuclear translocation was suppressed by tocilizumab. Tocilizumab suppressed inflammation via the TLR9 pathway by decreasing cfDNA levels. Regulation of cfDNA may be a therapeutic target for RA.

Expressions of circadian clock genes represent disease activities of RA patients treated with biological DMARDs.

Objectives: Rheumatoid Arthritis (RA) is the autoimmune disease representing the circadian variations of symptoms such as morning stiffness of joints or increased production of cytokines around midnight. Clock genes have been reported to affect on the pathogenesis of RA, however, the detailed relation between clock genes and disease activities of RA has remained unclear.Methods: In this study, 15 RA patients treated with biological disease modifying anti-rheumatic drugs (bDMARDs) were enrolled (TNF inhibitor, 5; IL-6 inhibitor, 5; CTLA4-IgG, 5). Blood samples were collected from RA patients before treatment and at the study end-point fulfilling DAS28-ESR < 3.2. Total RNA was extracted from leukocytes to examine the expressions of the clock genes. We then evaluated the correlation of the clock gene expression with disease activity and the diagnostic values of the clock genes.Results: The expressions of the clock genes were significantly modulated by bDMARDs treatments. Disease activities were significantly correlated with the clock genes expressions, and disease remission/low disease activity could be distinguished from moderate/high disease activity due to the sensitivities, the specificities and the areas under the curves of that.Conclusion: The expressions of the clock genes in leukocytes could be useful as novel biomarkers predicting disease activities and therapeutic efficacies for bDMARDs in RA treatments.

TNF-α induces expression of the circadian clock gene Bmal1 via dual calcium-dependent pathways in rheumatoid synovial cells.

Tumor necrosis factor (TNF)-α is responsible for expressions of several clock genes and affects joint symptoms of rheumatoid arthritis (RA) with diurnal fluctuation. We tried to determine the mechanism involved in over-expression of Bmal1, induced by TNF-α, in primary cultured rheumatoid synovial cells. Cells were incubated with intra-cellular Ca2+ chelator BAPTA-AM, calcineurin inhibitor FK506 and p300/CBP (CREB binding protein) inhibitor C646, respectively, or transfected with p300 and CBP small interfering RNA (siRNA) before stimulation with TNF-α. Oscillation phase and amplitude of Bmal1, transcriptional activator Rorα, transcriptional repressor Rev-erbα, and histone acetyltransferases (p300 and Cbp) were evaluated by quantitative real-time PCR. As results, TNF-α did not influence the oscillation phase of Rev-erbα, while enhanced those of Rorα, resulting in over-expression of Bmal1. When Ca2+ influx was inhibited by BAPTA-AM, TNF-α-mediated up-regulation of Rorα was cancelled, however, that of Bmal1 was still apparent. When we further explored another pathway between TNF-α and Bmal1, TNF-α suppressed the expression of Rev-erbα in the absence of Ca2+ influx, as well as those of p300 and Cbp genes. Finally, actions of TNF-α, in increasing Bmal1/Rorα and decreasing Rev-erbα, were cancelled by C646 treatment or silencing of both p300 and Cbp. In conclusion, we determined a novel role of TNF-α in inducing Bmal1 via dual calcium dependent pathways; Rorα was up-regulated in the presence of Ca2+ influx and Rev-erbα was down-regulated in the absence of that. Results proposed that inhibition of p300/CBP could be new therapeutic targets for RA.

Chronotherapy targeting cytokine secretion attenuates collagen-induced arthritis in mice.

OBJECTIVE: Diurnal variation of symptoms are observed in rheumatoid arthritis, especially in productions of cytokines that show peak concentrations during mid night. In contrast, cytokines of collagen-induced arthritis (CIA) mice increase in daytimes under Mid-light condition. By using chronotherapy, differences in drug efficacies according to administration time of Baricitinib, a wide ranged cytokine blocker, were examined in CIA mice. METHODS: CIA mice were administered a dose of 3 mg/kg of Baricitinib once a day at zeitgeber time (ZT) 0 or ZT12 for 21 days. Arthritis scores, histopathology and factors related to joint destruction in sera were examined. Phosphorylation of STAT3 in liver, expressions of cytokines in spleen, and Interleukin (IL)-6 and tumor necrosis factor (TNF)-α in sera were measured. RESULTS: In CIA mice, diurnal variations were observed both in expressions of cytokines and phosphorylation of STAT3. Arthritis scores of ZT0/12 group decreased from day3 as compared to untreated mice, and those of ZT0 group significantly decreased as compared to ZT12 group from day12. Pathological findings, immunohistochemistry of cytokines and Receptor activator of nuclear factor kappa-Β ligand (RANKL)/osteoprotegerin ratio in sera well reflected results of arthritis scores. Diurnal variation of STAT3 phosphorylation was suppressed in ZT0 group. At ZT2, expressions of IL-6/Interferon-γ/TNF/granulocyte-macrophage colony-stimulating factor in ZT0 group were significantly decreased as compared to untreated mice, though not in ZT12 group. In ZT0 group, IL-6 and TNF-α in sera were decreased for longer time than that in ZT12 group. CONCLUSION: Chronotherapy using Baricitinib targeting cytokine secretions is effective in CIA mice. Clinical applications of chronotherapy can be expected to enhance the drug efficacy.

Methotrexate upregulates circadian transcriptional factors PAR bZIP to induce apoptosis on rheumatoid arthritis synovial fibroblasts.

BACKGROUND: Effects of methotrexate (MTX) on the proliferation of rheumatoid arthritis (RA) synovial fibroblasts are incompletely understood. We explored actions of MTX in view of circadian transcriptions of synovial fibroblasts. METHODS: Under treatment with MTX, expression of core circadian clock genes, circadian transcriptional factor proline and acidic amino acid-rich basic leucine zipper (PAR bZIP), and proapoptotic molecule Bcl-2 interacting killer (Bik) was examined by real-time polymerase chain reaction. Protein expression of circadian clock gene PERIOD2 (PER2) and CYTOCHROME C was also examined by western blotting and ELISA. Promoter activities of Per2 and Bik were measured by Luciferase assay. Expression of PER2, BIK, and CYTOCHROME C and morphological changes of the nucleus were observed by fluorescent immunostaining. Synovial fibroblasts were transfected with Per2/Bik small interfering RNA, and successively treated with MTX to determine cell viabilities. Finally, synovial fibroblasts were treated with MTX according to the oscillation of Per2/Bik expression. RESULTS: MTX (10 nM) significantly decreased cell viabilities, but increased messenger RNA expression of Per2, Bik, and PAR ZIP including D site of the albumin promoter binding protein (Dbp), hepatic leukemia factor (Hlf), and thyrotroph embryonic factor (Tef). MTX also increased protein expression of PER2 and CYTOCHROME C, and promoter activities of Per2 and Bik via D-box. Under fluorescent observations, expression of PER2, BIK, and CYTOCHROME C was increased in apoptotic cells. Cytotoxicity of MTX was attenuated by silencing of Per2 and/or Bik, and revealed that MTX was significantly effective in situations where Per2/Bik expression was high. CONCLUSIONS: We present here novel unique action of MTX on synovial fibroblasts that upregulates PAR bZIP to transcribe Per2 and Bik, resulting in apoptosis induction. MTX is important in modulating circadian environments to understand a new aspect of pathogenesis of RA.

Circulating cell free DNA: a marker to predict the therapeutic response for biological DMARDs in rheumatoid arthritis.

AIM: To evaluate the correlation between circulating cell-free DNA (ccfDNA) in plasma and clinical disease activities in patients with rheumatoid arthritis (RA). METHOD: The study group included 30 patients with RA who started biological disease-modifying anti-rheumatic drugs (DMARDs) therapy. The concentration of ccfDNA in plasma was measured by quantitative real-time polymerase chain reaction at baseline to 24 weeks in every 4-week period from 30 patients and 21 healthy individuals. We also evaluated the correlation between ccfDNA and the clinical activity or the therapeutic response for biological DMARDs, using the simplified disease activity index (SDAI), Disease Activity Score of 28 joints (erythrocyte sedimentation rate) and the European League Against Rheumatism (EULAR) response criteria. Synovial fluid samples of knee joints were collected from 13 patients with RA and 12 with osteoarthritis (OA) to measure ccfDNA. RESULT: The concentration of ccfDNA in RA patients at baseline was higher than healthy controls (P = 0.016). After introducing biological DMARDs, ccfDNA was increased until 8 weeks from the baseline, and decreased after 12 weeks. The average of SDAI was improved in all patients enrolled. At 12 weeks after treatment, 15 patients were good responders to the EULAR response criteria, nine showed moderate response and six showed no response. ccfDNA in good responders was increased until 8 weeks, while those of moderate or no response were not (P = 0.042). In joint fluid of RA patients, ccfDNA was remarkably increased as compared to those from OA (P = 0.00011). CONCLUSION: After introducing biological DMARDs, increase of ccfDNA at 8 weeks was associated with improvement of disease activities. Compared with biomarkers reported, ccfDNA is able to predict the early therapeutic effects of biological DMARDs in RA patients.