Yasunori Tsubouchi

15-deoxy-delta(12,14)-PGJ(2) induces synoviocyte apoptosis and suppresses adjuvant-induced arthritis in rats.

Peroxisome proliferator–activated receptors (PPARs) are members of the nuclear hormone receptor superfamily and have a dominant regulatory role in adipocyte and monocyte differentiation. PPAR-γ agonists are also negative regulators of macrophage activation and have modulatory effects on tumorigenesis. In this study we demonstrate that synovial tissue localized expression of PPAR-γ in patients with rheumatoid arthritis (RA). We detected markedly enhanced expression of PPAR-γ in macrophages, as well as modestly enhanced expression in the synovial lining layer, fibroblasts, and endothelial cells. Activation of the PPAR-γ by 15-deoxy-Δ12,14-prostaglandin J2 (15d-PGJ2) and the synthetic PPAR-γ ligand (troglitazone) induced RA synoviocyte apoptosis in vitro. Moreover, intraperitoneal administration of these PPAR-γ ligands ameliorated adjuvant-induced arthritis with suppression of pannus formation and mononuclear cell infiltration in female Lewis rats. Anti-inflammatory effects of 15d-PGJ2 were more potent than troglitazone. These findings suggest that PPAR-γ may be an important immunoinflammatory mediator and its ligands, especially 15d-PGJ2, may be useful in the treatment of RA.

A Critical Role for Allograft Inflammatory Factor-1 in the Pathogenesis of Rheumatoid Arthritis

Rheumatoid arthritis (RA) is characterized by massive synovial proliferation, angiogenesis, subintimal infiltration of inflammatory cells and the production of cytokines such as TNF-α and IL-6. Allograft inflammatory factor-1 (AIF-1) has been identified in chronic rejection of rat cardiac allografts as well as tissue inflammation in various autoimmune diseases. AIF-1 is thought to play an important role in chronic immune inflammatory processes, especially those involving macrophages. In the current work, we examined the expression of AIF-1 in synovial tissues and measured AIF-1 in synovial fluid (SF) derived from patients with either RA or osteoarthritis (OA). We also examined the proliferation of synovial cells and induction of IL-6 following AIF-1 stimulation. Immunohistochemical staining showed that AIF-1 was strongly expressed in infiltrating mononuclear cells and synovial fibroblasts in RA compared with OA. Western blot analysis and semiquantitative RT-PCR analysis demonstrated that synovial expression of AIF-1 in RA was significantly greater than the expression in OA. AIF-1 induced the proliferation of cultured synovial cells in a dose-dependent manner and increased the IL-6 production of synovial fibroblasts and PBMC. The levels of AIF-1 protein were higher in synovial fluid from patients with RA compared with patients with OA (p < 0.05). Furthermore, the concentration of AIF-1 significantly correlated with the IL-6 concentration (r = 0.618, p < 0.01). These findings suggest that AIF-1 is closely associated with the pathogenesis of RA and is a novel member of the cytokine network involved in the immunological processes underlying RA.

Mycoplasma fermentans glycolipid-antigen as a pathogen of rheumatoid arthritis.

Mycoplasma fermentans has been suspected as one of the causative pathogenic microorganisms of rheumatoid arthritis (RA) however, the pathogenic mechanism is still unclear. We, previously, reported that glycolipid-antigens (GGPL-I and III) are the major antigens of M. fermentans. Monoclonal antibody against the GGPL-III could detect the existence of the GGPL-III antigens in synovial tissues from RA patients. GGPL-III antigens were detected in 38.1% (32/84) of RA patients tissues, but not in osteoarthritis (OA) and normal synovial tissues. Immunoelectron microscopy revealed that a part of GGPL-III antigens are located at endoplasmic reticulum. GGPL-III significantly induced TNF-alpha and IL-6 production from peripheral blood mononulear cells, and also proliferation of synovial fibroblasts. Further study is necessary to prove that M. fermentans is a causative microorganism of RA; however, the new mechanisms of disease pathogenesis provides hope for the development of effective and safe immunotherapeutic strategies based on the lipid-antigen, GGPL-III, in the near future.

Auranofin inhibits interleukin-1β-induced transcript of cyclooxygenase-2 on cultured human synoviocytes

The aim of this study was to characterize the effects of auranofin (2,3,4,6-tetra-O-acetyl-l-thio-beta-D-gluco-pyranosato-S) on cyclooxygenase expression and prostaglandin E(2) synthesis on cultured human synovial fibroblast-like cells (synoviocytes). Synoviocytes were treated with auranofin in the presence or absence of interleukin-1beta. Cultured supernatants were harvested for prostaglandin E(2) synthesis. Cyclooxygenase-1 and -2 expression was analyzed with Western and Northern blotting. Translocation of nuclear factor-kappa B p65 was determined by immunostaining. Cytotoxicity was measured with 51Cr release assay. Auranofin attenuated interleukin-1beta-induced prostaglandin E(2) production of the cells in a dose-dependent fashion. Auranofin selectively suppressed interleukin-1beta-induced cyclooxygenase-2 mRNA and protein expression of the cells without alteration of cyclooxygenase-1 expression. Also, auranofin interfered with interleukin-1beta-induced translocation of nuclear factor-kappa B. These inhibitory effects did not originate in the cytotoxicity of the agent. Our data indicate that auranofin inhibits interleukin-1beta-induced prostaglandin E(2) synthesis and cyclooxygenase-2 expression via suppression of nuclear factor-kappa B activation on synoviocytes.

Preferential inhibition of cyclooxygenase-2 by meloxicam in human rheumatoid synoviocytes

The aim of this study was to evaluate the anti-inflammatory effect of 4-hydroxy-2-methyl-N-[5-methyl-2-thiazolyl]-2H-1, 2-benzothiazine-3-carboxamide-1,1-dioxide (meloxicam) using cultured rheumatoid synovial fibroblast-like cells (synoviocytes). Synoviocytes were treated with meloxicam in the presence or absence of interleukin-1beta. Meloxicam had no effect on both cyclooxygenase-1 and -2 expression as determined by Western blot analysis, immunohistochemical staining, and reverse transcription polymerase chain reaction (RT-PCR). Even the lower doses of meloxicam inhibited cyclooxygenase-2 activity, but only the higher doses of meloxicam inhibited cyclooxygenase-1 activity as determined by prostaglandin E(2) synthesis assay. So meloxicam had a preferential inhibitory effect of cyclooxygenase-2 relative to cyclooxygenase-1 on cultured rheumatoid synoviocytes without affecting cyclooxygenase expression. On the other hand, indomethacin had no selectivity and dexamethasone inhibited the expression of cyclooxygenase-2. Our data indicate that clinical efficacy and safety of meloxicam for rheumatoid arthritis may result from its preferential inhibition of cyclooxygenase-2 activity relative to cyclooxygenase-1 on rheumatoid synoviocytes.

Contribution of rheumatoid arthritis disease activity and disability to rheumatoid cachexia

This cross-sectional study was done to show how nutritional indices influence each other and the contributions made by inflammation to the development of rheumatoid cachexia. We studied 295 female patients with rheumatoid arthritis (RA). We chose five nutritional indices: body mass index (BMI), arm muscle area (AMA), triceps skinfold thickness (TSF), which were obtained via anthropometric measurements, and serum albumin and cholesterol. Clinical indicators of RA included disease duration, C-reactive protein (CRP) and Disease Activity Score 28 (DAS28). We performed a bivariate correlation test between the nutritional indices and multiple regression analysis for each nutritional index. Mean AMA was low, 87.3% of the normal value, whereas TSF was not different. Muscle protein expressed by AMA decreased according to RA duration, whereas visceral protein indicated by serum albumin decreased with an increase in RA activity. The continuation of inflammation appears to be essential for a decrease in muscle protein in rheumatoid cachexia. DAS28 showed a positive contribution to BMI in the regression model, and the increase in RA disease activity causes an increase in BMI via an accumulation of tissue fat.

Pneumatosis intestinalis and hepatic portal venous gas caused by gastrointestinal perforation with amyloidosis.

To the Editor: Hepatic portal venous gas (HPVG) is a rare sign to demonstrate the existence of intraportal gas with severe disorders such as bowel necrosis. Pneumatosis intestinalis (PI) is the pathology in which a lot of pneumatic cysts exist in a gut wall, and this is the indication associated with the bowel damage like necrosis. We experienced the rare case with both HPVG and PI caused by secondary amyloidosis with rheumatoid arthritisis, who recovered by conservative treatment. A 63-year-old woman with rheumatoid arthritis (RA) for about 10 years has been followed up by no treatment. Oral administration of bucillamine for RA was started in 1999. A steroid intra-articular injection, treatment by methotrexate oral administration were performed afterward, too, but had difficulty with control. In March 2005, she canceled treatment of then herself, and chose treatment by Chinese medicine, but after all, she came to show diarrhea, a vomiting symptom from July, and she was hospitalized because of her symptom aggravation in October. It led to diagnosis of secondary amyloidosis associated with RA by endoscopic examination of the colon when she was hospitalized with the symptom again in January 2006. During hospitalization, she showed fresh blood bloody excrement and we performed abdominal computed tomography. It showed pneumatic presence in liver, pancreas, a gut wall, and free air intraperitoneally, and so we diagnosed it as HPVG and PI caused by lower digestive tract perforation (Figs. 1, 2). The gas disappeared by conservative treatment after half day. In many cases with conservative treatment, disappearance of HPVG and PI are found in an early stage (24 to 48h). In this case, the possible pathologic mechanism is as follows: when bowel pressure kept in a high state and gastrointestinal perforation occurred, air entered at the failed blood vessel and moved to the portal venous system. A lot of air was diffusely found in liver and pancreas in this image, but we did not recognize exacerbation of liver function and suggestive data of pancreatitis in blood examination, and those of peritonitis with intestinal perforation, so she recovered with only conservative treatment in an early stage of PI. PI is associated with various diseases: ileus, osmotic pressure enhancement, obstructive pulmonary disease, necrotizing enterocolitis, etc. HPVG is caused by mucosal damage, bowel distension, sepsis, and so on. However, amyloidosis is also one of the causes of HPVG and PI, there were extremely few reports of HPVG FIGURE 1. Pneumatic presence was in pancreas and a gut wall. Arrows indicate free air intraperitoneally.

Eicosapentaenoic Acid Suppresses the Proliferation of Synoviocytes from Rheumatoid Arthritis

Eicosapentaenoic acid (EPA) is essential for normal cell growth, and may play an important role in inflammatory and autoimmune disorders including rheumatoid arthritis. We investigate that EPA could suppress the proliferation of fibroblast like synoviocytes in vitro. We treated synoviocytes with 1 to 50 µM EPA and measured cell viabilities by the modified MTT assay. We sorted the number of them in sub G1 stage by fluorescence-activated cell sorting caliber. And we stained them by light green or Hoechst 33258, and investigate microscopic appearance. The cell viabilities were decreased at 30 µM, 40 µM, and 50 µM of EPA comparing to 0 µM of EPA. The half maximal concentration of synoviocytes inhibition was approximately 25 µM. At day 1 and day 3, cell number was also decreased at 50 µM EPA comparing to control. FACS caliber indicated the number of synoviocytes in sub G1 stage did not increase in each concentration of EPA. Hoechst staining indicated normal chromatin pattern and no change in a nuclear morphology both in EPA treated synoviocytes and in untreated synoviocytes. These findings suggest that EPA could suppress the proliferation of synoviocytes in vivo dose dependently and time dependently, however, the mechanism is not due to apoptosis.

Feedback Control of the Arachidonate Cascade in Osteoblastic Cells by 15-deoxy-Δ12,14-Prostaglandin J2

15-deoxy-Δ12,14-prostaglandin J2 (15d-PGJ2) and an anti-diabetic thiazolidinedione, troglitazone (TRO) are peroxisome proliferator-activated receptor (PPAR)-γ ligands, which regulate immuno-inflammatory reactions as well as adipocyte differentiation. We previously reported that 15d-PGJ2 can suppress interleukin (IL)-1β-induced prostaglandin E2 (PGE2) synthesis in synoviocytes of rheumatoid arthritis (RA). IL-1 also stimulates PGE2 synthesis in osteoblasts by regulation of cyclooxygenase (COX)-2 and regulates osteoclastic bone resorption in various diseases such as RA and osteoporosis. In this study, we investigated the feedback mechanism of the arachidonate cascade in mouse osteoblastic cells, MC3T3-E1 cells, which differentiate into mature osteoblasts. Treatment with 15d-PGJ2 led to a significant increase in IL-1α-induced COX-2 expression and PGE2 production in a dose dependent manner. The effect of 15d-PGJ2 was stronger than that of TRO. However, it did not affect the expression of COX-1. In addition, cell viability of MC3T3-E1 cells was not changed in the condition we established. This means that 15d-PGJ2 exerts a positive feedback regulation of the arachidonate cascade of PGE2 in osteoblastic cells. These results may provide important information about the pathogenesis and treatment of bone resorption in a variety of diseases such as RA and osteoporosis.

Combination therapy of prednisolone and mizoribine improves cryoglobulinemic vasculitis with purpura and skin ulcers.

Conventional treatment is not standardized for hepatitis C virus-negative cryoglobulinemia, but corticosteroids, immunosuppressive agents, and plasma exchange typically improved the symptoms. Mizoribine is an immunosuppressive agent that was developed in Japan and has been found to inhibit the proliferation of lymphocytes, especially B cells. We have encountered an elder patient who had hepatitis C virus-negative, type II cryoglobulinemic vasculitis with leg purpura and skin ulcers. Her symptoms improved and cryoglobulin disappeared by the combination therapy of prednisolone and mizoribine. We speculate the action mechanism of this therapy is due to immunosuppressive effects including up-regulation of the efficacy of prednisolone by mizoribine.