cytochrome-c-t and Arthritis--Rheumatoid

We postulate that 10-formyl-7,8-dihydrofolate (10-HCO-H(2)folate), not 10-formyl-5,6,7,8-tetrahydrofolate (10-HCO-H(4)folate), is the predominant in vivo substrate for mammalian aminoimidazolecarboxamide ribotide (AICAR) transformylase, an enzyme in purine nucleotide biosynthesis de novo, which introduces carbon 2 (C(2)) into the purine ring. 10-HCO-H(2)folate exists in vivo as labeled 10-formyl-folic acid (10-HCO-folic acid: an oxidation product of 10-HCO-H(4)folate and 10-HCO-H(2)folate) and is found after doses of labeled folic acid in humans or laboratory animals. The bioactivity of the unnatural isomer, [6R]-5-formyltetrahydrofolate, in humans is explained by its in vivo conversion to 10-HCO-H(2)folate. The structure and active site of AICAR transformylase are not consistent with other enzymes that utilize 10-HCO-H(4)folate. Because 10-HCO-H(4)folate is rapidly oxidized in vitro to 10-HCO-H(2)folate by cytochrome C alone and in mitochondria, it is hypothesized that this process takes place in vivo. In vitro data indicate that 10-HCO-H(2)folate is kinetically preferred over 10-HCO-H(4)folate by AICAR transformylase and that this enzyme may not have access to sufficient supplies of 10-HCO-H(4)folate. Methotrexate blockage of the AICAR transformylase process in patients with rheumatoid arthritis suggests that dihydrofolate (H(2)folate) reductase is involved and is consistent with H(2)folate and 10-HCO-H(2)folate being the product and substrate for AICAR transformylase. The labeling of purine C(2) by an oral dose of [6RS]-5-H[(13)C]O-H(4)folate in a human subject is consistent with 10-H[(13)C]O-H(2)folate formation from unnatural isomer, [6R]-5-H[(13)C]O-H(4)folate, and it being a substrate for AICAR transformylase. In vitro exchange reactions of purine C(2) using H(4)folate coenzymes are not duplicated in vivo and is consistent with H(2)folate coenzymes being used in vivo by AICAR transformylase.

Topics: Administration, Oral; Animals; Arthritis, Rheumatoid; Carbon; Cytochromes c; Folic Acid; Humans; Kinetics; Methotrexate; Mitochondria; Phosphoribosylaminoimidazolecarboxamide Formyltransferase; Purines; Recombinant Proteins; Substrate Specificity

α-Mangostin (α-M) is a commonly used traditional medicine with various biological and pharmacological activities. Our study aimed to explore the effects and mechanism of α-M in regulating apoptosis of rheumatoid arthritis fibroblast-like synoviocytes (RA-FLS). α-M of 10 to 100 μM was used to treat RA-FLS for 24 hours, followed by measuring cell viability and apoptosis. The involvement of reactive oxygen species (ROS) and mitogen-activated protein kinases was detected. Treatment of α-M promoted apoptosis and reduced viability of RA-FLS in a dose-dependent manner. The mitochondrial membrane potential in RA-FLS was remarkably reduced by α-M treatment, accompanied by the cytochrome c accumulation in the cytosol and increased activities of caspase-3 and caspase-9. Moreover, we found that α-M treatment promoted ROS production and extracellular signal-regulated kinase 1/2 (ERK1/2) phosphorylation. The proapoptotic activity of α-M in RA-FLS was markedly reversed by the co-induction with the ERK1/2 inhibitor LY3214996 or ROS scavenger N-acetyl-l-cysteine. In conclusion, our studies found that α-M had remarkable proapoptotic activities in RA-FLS, which is regulated by the induction of ROS accumulation and ERK1/2 phosphorylation. α-M may thus have potential therapeutic effects for rheumatoid arthritis.

Topics: Acetylcysteine; Aged; Apoptosis; Arthritis, Rheumatoid; Benzamides; Caspase 3; Caspase 9; Cell Survival; Cytochromes c; Female; Humans; MAP Kinase Signaling System; Membrane Potential, Mitochondrial; Middle Aged; Mitogen-Activated Protein Kinase 1; Mitogen-Activated Protein Kinase 3; Protein Kinase Inhibitors; Reactive Oxygen Species; Sulfonamides; Synoviocytes; Xanthones

T cells play an essential role in the pathogenesis of both human rheumatoid arthritis (RA) and its murine models. A key molecule in T cell activation is ZAP-70, therefore we aimed to investigate the effects of partial ZAP-70 deficiency on the pathogenesis of recombinant human G1(rhG1)-induced arthritis (GIA), a well-established mouse model of RA. Arthritis was induced in BALB/c and ZAP-70

Topics: Adaptor Proteins, Signal Transducing; Aggrecans; Animals; Apoptosis; Arthritis, Rheumatoid; Autoantibodies; Autoimmunity; Bcl-2-Like Protein 11; Caspase 3; Cells, Cultured; Cytochromes c; Cytokines; Disease Models, Animal; Disease Progression; Female; Gene Knockout Techniques; Humans; Immunoglobulin Fc Fragments; Immunoglobulin G; Lymphocyte Activation; Mice; Mice, Inbred BALB C; Mice, Knockout; Proto-Oncogene Proteins c-bcl-2; Proto-Oncogene Proteins c-cbl; Spleen; T-Lymphocytes; ZAP-70 Protein-Tyrosine Kinase

Oridonin, an active diterpenoid compound from Rabdosia rubescens, has anti-tumor effects. Rheumatoid arthritis fibroblast-like synoviocytes (RAFLS), a pathological hallmark of RA, exhibits "tumor-like" phenotype. Here, we investigated the effects of oridonin on the proliferation and apoptosis of RAFLS. Cell viability was measured by the 3-(4,5-dimethylthiazol-2-yl)-2,5-diphenyl-tetrazolium bromide (MTT) assay. Apoptosis and mitochondrial membrane potential were detected by flow cytometry. Western blot analysis was performed to examine the phosphorylation of extra-cellular regulated kinases (ERK1/2), C-Jun N-Terminal Kinase (JNK), and p38 mitogen-activated protein kinases and the expression of apoptosis-related proteins. Oridonin inhibited cell proliferation and induced cell apoptosis in interleukin-1β (IL-1β)-treated FLS. z-VAD-fmk, a pan-caspase inhibitor, significantly (P < 0.05) attenuated oridonin-induced apoptosis of FLS. Oridonin suppressed IL-1β-mediated phosphorylation of ERK1/2 and JNK in a dose-dependent manner. Meanwhile, oridonin alone dose-dependently suppressed FLS proliferation, triggered cell apoptosis, and reduced mitochondrial membrane potential (ΔΨm) through activating caspase-3, caspase-9, and PARP, leading to translocation of cytochrome c into cytoplasm. z-VAD-fmk significantly (P < 0.05) inhibited oridonin-induced apoptosis. The accumulation of cellular reactive oxygen species (ROS) was about sevenfold increase in oridonin-treated cells. Pretreatment of N-acetylcysteine (NAC), an inhibitor of ROS, significantly attenuated oridonin-triggered apoptosis, indicating the involvement of ROS production in oridonin-induced mitochondrial apoptosis. Oridonin inhibits cell proliferation, induces cell apoptosis, and decreases the phosphorylation of ERK1/2 and JNK in IL-1β-exposed RAFLS. Oridonin induces mitochondrial apoptosis by enhancing the production of ROS in FLS.

Topics: Acetylcysteine; Amino Acid Chloromethyl Ketones; Apoptosis; Arthritis, Rheumatoid; Caspase 3; Caspase 9; Cell Line; Cell Proliferation; Cell Survival; Cytochromes c; Diterpenes, Kaurane; Extracellular Signal-Regulated MAP Kinases; Fibroblasts; Humans; Interleukin-1beta; JNK Mitogen-Activated Protein Kinases; Membrane Potential, Mitochondrial; Mitochondria; p38 Mitogen-Activated Protein Kinases; Phosphorylation; Poly(ADP-ribose) Polymerases; Reactive Oxygen Species; Synoviocytes

Tanshinone IIA (Tan IIA), a phytochemical derived from the roots of Salvia miltiorrhiza BUNGE, has been documented with anti-tumor, pro-apoptotic, and anti-inflammatory activities. Salvia miltiorrhiza has long been used to treat rheumatoid arthritis (RA). Apoptosis induction of RA-fibroblast-like synoviocytes (FLS) was suggested to be a potential therapeutic approach for RA. The aim of this study was to investigate whether Tan IIA promotes apoptosis in RA-affected FLS. In this study, the viability of an immortalized FLS cell line derived from RA patients was assessed by 3-(4,5-dimethylthiazol-2-yl)-5,3-carboxymethoxyphenyl-2,4-sulfophenyl-2H-tetrazolium (MTS) assay after Tan IIA treatment. Apoptosis was measured by terminal deoxyuridine triphosphate (dUTP) nick-end labeling (TUNEL) assay and flow cytometry. Cell cycle was evaluated by flow cytometry. The expressions of mitochondrial apoptosis-related molecules, including Bcl-2, Bax, mitochondrial cytochrome c (Cyt-c), cytosolic Cyt-c, apoptotic protease activating factor 1 (Apaf-1), procaspase-9, procaspase-3, caspase-9, and caspase-3 were determined by Western blotting. Our data demonstrate that Tan IIA induced apoptosis of RA-FLS, blocked the cell cycle in the G2/M phase, and regulated the protein expression of Bcl-2, Bax, and Apaf-1, the release of mitochondrial Cyt-c, and the activation of caspase-9 and caspase-3. The results support the conclusion Tan IIA treatment likely induces apoptosis of RA-FLS through blockade of the cell cycle in the G2/M phase and a mitochondrial pathway. These data suggest that Tan IIA may have therapeutic potential for RA.

Topics: Abietanes; Apoptosis; Apoptotic Protease-Activating Factor 1; Arthritis, Rheumatoid; bcl-2-Associated X Protein; Caspase 3; Caspase 9; Cell Cycle; Cell Line; Cytochromes c; Fibroblasts; Humans; Mitochondria; Proto-Oncogene Proteins c-bcl-2

In the present study, we sought to explore the mechanism of quercetin-induced apoptosis in rheumatoid arthritis fibroblast-like synoviocytes (RAFLSs). DNA fragmentation assay was used to detect quercetin-induced apoptosis in RAFLSs. The cleavages of caspase-3 and caspase-9 and the accumulation of cytosolic cytochrome C were measured by western blot in quercetin-treated RAFLSs. Mitochondrial membrane potential was tested by flow cytometry. Small interfering RNAs were used to knock down the expression of protein 53 (p53) and analyze the role of p53 in quercetin-induced apoptosis in RAFLSs. DNA fragmentation assay showed that quercetin dose-dependently elevated the apoptosis of RAFLSs, accompanying with enhanced caspase-3 and caspase-9 cleavages. Moreover, quercetin caused a concentration-dependent loss of mitochondrial membrane potential and cytochrome c release to cytosol and also decreased Bcl-2/Bax ratio, indicating that quercetin-induced apoptosis is through mitochondrial pathway. Quercetin also elevated p53 phosphorylation at ser15. Pretreatment with pifithrin-α, a p53 inhibitor, significantly diminished p53 phosphorylation at the concentration of 30 μM and abrogated quercetin-induced apoptosis in a dose-dependent manner. Quercetin-induced apoptosis was also significantly blocked by p53 silencing, further suggesting the involvement of p53 in quercetin-induced apoptosis in RAFLSs. Our study indicated that quercetin-induced apoptosis of RAFLSs is through mitochondrial pathway, in which p53 plays an important role.

Topics: Antioxidants; Apoptosis; Arthritis, Rheumatoid; bcl-2-Associated X Protein; Benzothiazoles; Caspase 3; Caspase 9; Cells, Cultured; Cytochromes c; DNA Fragmentation; Enzyme Activation; Fibroblasts; Humans; Membrane Potential, Mitochondrial; Phosphorylation; Proto-Oncogene Proteins c-bcl-2; Quercetin; RNA Interference; RNA, Small Interfering; Synovial Membrane; Toluene; Tumor Suppressor Protein p53

Resveratrol, a phytoalexin, reduced the viability of MH7A cells, a human rheumatoid arthritis synovial cell line. In the apoptosis assay, resveratrol increased TUNEL-positive cells and stimulated H2A.X phosphorylation. Resveratrol disrupted mitochondrial membrane potentials in MH7A cells and stimulated cytochrome c release from the mitochondria to the cytosol. Resveratrol activated caspase-3 and caspase-9 but not caspase-8 in MH7A cells. Resveratrol upregulated the expression of the NAD-dependent deacetylase sirtuin 1 mRNA and downregulated the expression of the Bcl-X(L) mRNA, and resveratrol-induced MH7A cell death, mitochondrial damage, and caspase-3/-9 activation were prevented by sirtinol, an inhibitor of sirtuin 1. The results of the present study show that resveratrol induces MH7A cell apoptosis by activating caspase-9 and the effector caspase-3 along mitochondrial disruption as a result of reduced Bcl-X(L) expression, allowing cytochrome c release from the mitochondria into the cytosol, in a sirtuin 1-dependent manner. This suggests that resveratrol could suppress hyperplasia of synovial cells, a critical factor of rheumatoid arthritis.

Topics: Anti-Inflammatory Agents, Non-Steroidal; Apoptosis; Arthritis, Rheumatoid; bcl-X Protein; Benzamides; Caspase 3; Caspase 9; Cell Line; Cytochromes c; Humans; Mitochondria; Naphthols; Resveratrol; Sirtuin 1; Stilbenes; Synovial Membrane; Up-Regulation

The pseudo-tumoral expansion of fibroblast-like synoviocytes is a hallmark of rheumatoid arthritis (RA), and targeting rheumatoid arthritis fibroblast-like synoviocytes (RAFLSs) may have therapeutic potentials in this disease. Andrographolide, a diterpenoid compound isolated from the herb Andrographis paniculata, has been reported to have potent anti-inflammatory activity. In the present study, we aimed to investigate the effects of andrographolide on human RAFLSs and the underlying molecular mechanism(s). RAFLSs were isolated from patients with RA and treated with or without various concentrations (i.e., 10, 20, and 30 μM) of andrographolide for 48 h. 3-[4,5-Dimethyl-2-yl]-2,5-diphenyl tetrazolium bromide assay revealed that andrographolide treatment decreased the proliferation of RAFLSs in a dose-dependent manner. Cell cycle analysis using propidium iodide (PI) staining showed a G0/G1 cell cycle arrest in andrographolide-treated RAFLSs. Immunoblotting analysis of key cell cycle regulators demonstrated that andrographolide treatment caused a dose-dependent increase in the expression of cell-cycle inhibitors p21 and p27 and a concomitant reduction of cyclin-dependent kinase 4. Exposure to andrographolide-induced apoptosis of RAFLSs measured by annexin V/PI double staining, which was coupled with promotion of cytochrome C release from mitochondria and activation of caspase-3. Moreover, andrographolide-treated RAFLSs displayed a significant decrease in the Bcl-2/Bax ratio compared to untreated cells. In conclusion, our data demonstrate that andrographolide exerts anti-growth and pro-apoptotic effects on RAFLSs, thus may have therapeutic potential for the treatment of RA.

Topics: Anti-Inflammatory Agents; Apoptosis; Arthritis, Rheumatoid; bcl-2-Associated X Protein; Caspase 3; Cell Cycle Checkpoints; Cell Survival; Cells, Cultured; Cyclin-Dependent Kinase 4; Cyclin-Dependent Kinase Inhibitor p21; Cyclin-Dependent Kinase Inhibitor p27; Cytochromes c; Diterpenes; Dose-Response Relationship, Drug; Fibroblasts; Humans; In Vitro Techniques; Proto-Oncogene Proteins c-bcl-2; Synovial Fluid

T cells play an important role in the initiation and the progression of rheumatoid arthritis (RA) and depletion of potentially pathogenic T cells was suggested as an important therapeutic protocol. We determined if rosmarinic acid (RosA), known as a secondary metabolite from herbal plants, had apoptotic activity toward T cells from RA patients and further verified target T-cell subsets. CD3(+)CD25(+) activated T-cell subsets from most of the RA patients displayed significantly higher apoptosis rates than did the PBMCs and total CD3(+) T cells. Furthermore, activated and effector CD4(+) T cells, including CD4(+)CD25(+) and CD4(+)CD45RO(+) T cells, had a tendency of being more susceptible to RosA-induced apoptosis than that of resting and naïve T-cell subsets. RosA induced the release of cytochrome c from mitochondria and the blockage of mitochondrial depolarization inhibited apoptosis. Taken together, these results suggest that RosA induces apoptosis of activated T-cell subsets from RA patients via a mitochondrial pathway.

Topics: Adult; Aged; Apoptosis; Arthritis, Rheumatoid; CD3 Complex; Cells, Cultured; Cinnamates; Cytochromes c; Depsides; Female; Humans; Interleukin-2 Receptor alpha Subunit; Intracellular Membranes; Lymphocyte Activation; Male; Membrane Potentials; Middle Aged; Mitochondria; Rosmarinic Acid; T-Lymphocyte Subsets; T-Lymphocytes, Regulatory

The aim of the study was to assess the role of extracellular cytochrome c as an inducer of joint inflammation and to examine its levels in sera and synovial fluids of rheumatoid arthritis (RA) patients.. Mice were injected intra-articularly with different doses of cytochrome c and joints were evaluated histopathologically and immunohistochemically 3 and 10 days later. In addition, mouse spleen cells were stimulated with different concentrations of cytochrome c, followed by assessment of NF-kappaB activation and cytokine production. Sera and synovial fluid from RA patients and sera from healthy individuals were assessed with respect to cytochrome c levels by an enzyme-linked immunoassay technique.. Histopathological signs of arthritis were evident in 75% of animals following intra-articular injection of cytochrome c. Synovitis was characterized by influx of Mac-1+ cells. In vivo depletion of neutrophils and monocytes led to abrogation of arthritis. Stimulation of mouse spleen cells in vitro with cytochrome c resulted in activation of NF-kappaB and release of proinflammatory cytokines and chemokines. Cytochrome c levels in RA patients' sera were significantly lower than in healthy controls. Further, cytochrome c levels in synovial fluid were significantly lower than in corresponding blood samples.. Our findings demonstrate that extracellular cytochrome c displays direct proinflammatory properties mediated by activation of NF-kappaB and causing neutrophil and monocyte triggered inflammation. We hypothesize that decreased levels of cytochrome c in RA patients reflect consumption of this molecule in the synovial tissue, decreasing apoptosis and shifting the balance towards inflammation.

Topics: Adult; Aged; Animals; Apoptosis; Arthritis, Experimental; Arthritis, Rheumatoid; Cells, Cultured; Chemokines; Cytochromes c; Electrophoretic Mobility Shift Assay; Extracellular Fluid; Female; Humans; Injections, Intra-Articular; Mice; Mice, Inbred BALB C; Middle Aged; Neutrophils; NF-kappa B; Spleen; Synovial Fluid