Long-term effects of abatacept on atherosclerosis and arthritis in older vs. younger patients with rheumatoid arthritis: 3-year results of a prospective, multicenter, observational study

BACKGROUND

We aimed to reveal the effect of abatacept (ABT) on atherosclerosis in rheumatoid arthritis (RA) patients, 3-year efficacy for arthritis, and safety in a population of older vs. younger patients.

METHODS

In this open-label, prospective, observational study, patients were stratified into four groups: younger (20-64 years old) and older (≥ 65 years) patients taking ABT (AY and AO) and conventional synthetic disease-modifying antirheumatic drugs (csDMARDs) (CY and CO). Primary endpoints were change from baseline in mean intima-media thickness (IMT) of the common carotid artery, IMT max (bulbus, bifurcation, and internal and common carotid artery), and plaque score at Week 156. Disease activity, retention rate, and adverse effects were also evaluated.

RESULTS

The ABT group (AY + AO) tended to have smaller increases in mean IMT, max IMT, and plaque score than the csDMARD group (CY + CO) at Week 156, although the differences between groups were not statistically significant. Multivariate analysis showed significantly lower increases in plaque score with ABT than with csDMARDs, only when considering disease activity at 156 weeks (p = 0.0303). Proportions of patients with good or good/moderate European League Against Rheumatism response were higher in the ABT group, without significant difference between older and younger patients. No significant differences were observed in ABT retention rates between older and younger patients. Serious adverse effects, especially infection, tended to be more frequent with ABT than with csDMARDs, although no significant differences were found.

CONCLUSIONS

ABT may decelerate atherosclerosis progression and may be useful for patients with high risk of cardiovascular disease, such as older patients.

TRIAL REGISTRATION NUMBER

UMIN000014913.

Relationship Between the Lipidome Profile and Disease Activity in Patients with Rheumatoid Arthritis

Lipid mediators have been suggested to play important roles in the pathogenesis of rheumatoid arthritis (RA). Lipidomics has recently allowed for the comprehensive analysis of lipids and has revealed the potential of lipids as biomarkers for the early diagnosis of RA and prediction of therapeutic responses. However, the relationship between disease activity and the lipid profile in RA remains unclear. In the present study, we performed a plasma lipidomic analysis of 278 patients with RA during treatment and examined relationships with disease activity using the Disease Activity Score in 28 joints (DAS28)-erythrocyte sedimentation rate (ESR). In all patients, five lipids positively correlated and seven lipids negatively correlated with DAS28-ESR. Stearic acid [FA(18:0)] (r = -0.45) and palmitic acid [FA(16:0)] (r = -0.38) showed strong negative correlations. After adjustments for age, body mass index (BMI), and medications, stearic acid, palmitic acid, bilirubin, and lysophosphatidylcholines negatively correlated with disease activity. Stearic acid inhibited osteoclast differentiation from peripheral blood monocytes in in vitro experiments, suggesting its contribution to RA disease activity by affecting bone metabolism. These results indicate that the lipid profile correlates with the disease activity of RA and also that some lipids may be involved in the pathogenesis of RA.

Activation of cytotoxic lymphocytes through CD6 enhances killing of cancer cells

Immune checkpoint inhibitors (ICIs) have demonstrated efficacy and improved survival in a growing number of cancers. Despite their success, ICIs are associated with immune-related adverse events that can interfere with their use. Therefore, safer approaches are needed. CD6, expressed by T-lymphocytes and human NK cells, engages in cell-cell interactions by binding to its ligands CD166 (ALCAM) and CD318 (CDCP1). CD6 is a target protein for regulating immune responses and is required for the development of several mouse models of autoimmunity. Interestingly, CD6 is exclusively expressed on immune cells while CD318 is strongly expressed on most cancers. Here we demonstrate that disrupting the CD6-CD318 axis with UMCD6, an anti-CD6 monoclonal antibody, prolongs survival of mice in xenograft mouse models of human breast and prostate cancer, treated with infusions of human lymphocytes. Analysis of tumor-infiltrating immune cells showed that augmentation of lymphocyte cytotoxicity by UMCD6 is due to effects of this antibody on NK, NKT and CD8 + T cells. In particular, tumor-infiltrating cytotoxic lymphocytes from UMCD6-treated mice expressed higher levels of perforin and were found in higher proportions than those from IgG-treated mice. Moreover, RNA-seq analysis of human NK-92 cells treated with UMCD6 revealed that UMCD6 up-regulates the NKG2D-DAP10 receptor complex, important in NK cell activation, as well as its downstream target PI3K. Our results now describe the phenotypic changes that occur on immune cells upon treatment with UMCD6 and further confirm that the CD6-CD318 axis can regulate the activation state of cytotoxic lymphocytes and their positioning within the tumor microenvironment.

Activation of Cytotoxic Lymphocytes Through CD6 Enhances Killing of Cancer Cells

Immune checkpoint inhibitors (ICIs) have demonstrated efficacy and improved survival in a growing number of cancers. Despite their success, ICIs are associated with immune-related adverse events that can interfere with their use. Therefore, safer approaches are needed. CD6, expressed by T-lymphocytes and human NK cells, engages in cell-cell interactions by binding to its ligands CD166 (ALCAM) and CD318 (CDCP1). CD6 is a target protein for regulating immune responses and is required for the development of several mouse models of autoimmunity. Interestingly, CD6 is exclusively expressed on immune cells while CD318 is strongly expressed on most cancers. Here we demonstrate that disrupting the CD6-CD318 axis with UMCD6, an anti-CD6 monoclonal antibody, prolongs survival of mice in xenograft models of human breast and prostate cancer, treated with infusions of human lymphocytes. Analysis of tumor-infiltrating immune cells showed that augmentation of lymphocyte cytotoxicity by UMCD6 is due to effects of this antibody on NK, NKT and CD8+ T cells. Tumor-infiltrating cytotoxic lymphocytes were found in higher proportions and were activated in UMCD6-treated mice compared to controls. Similar changes in gene expression were observed by RNA-seq analysis of NK cells treated with UMCD6. Particularly, UMCD6 up-regulated the NKG2D-DAP10 complex and activated PI3K. Thus, the CD6-CD318 axis can regulate the activation state of cytotoxic lymphocytes and their positioning within the tumor microenvironment.

Clinical characteristics of COVID-19 patients with underlying rheumatic diseases in Japan: data from a multicenter observational study using the COVID-19 Global Rheumatology Alliance physician-reported registry

INTRODUCTION

To describe clinical characteristics of patients in Japan with coronavirus disease 19 (COVID-19) and pre-existing rheumatic disease and examine the possible risk factors associated with severe COVID-19.

METHODS

Adults with rheumatic disease and a COVID-19 diagnosis who were registered in the COVID-19 Global Rheumatology Alliance (C19-GRA) physician-reported registry from Japan between 15 May 2020 and 12 May 2021 were included. Multivariable logistic regression models were used to assess factors associated with severe COVID-19 progression, defined as death or requiring oxygen inhalation.

RESULTS

In total, 222 patients were included in the study. Rheumatoid arthritis (48.2%), gout (14.4%), and systemic lupus erythematosus (8.1%) were the most common types of rheumatic disease, 55.1% of patients were in remission and 66.2% had comorbid disease. Most patients were hospitalised (86.9%) for COVID-19, 43.3% received oxygen, and 9.0% died. Older age (≥ 65 years), corticosteroid use, comorbid diabetes, and lung diseases are associated with higher risk for severe COVID-19 progression (odds ratio (OR) 3.52 [95% confidence interval (CI) 1.69-7.33], OR 2.68 [95% CI 1.23-5.83], OR 3.56 [95% CI 1.42-8.88], and OR 2.59 [95% CI 1.10-6.09], respectively).

CONCLUSIONS

This study described clinical characteristics of COVID-19 patients with rheumatic diseases in Japan. Several possible risk factors for severe COVID-19 progression were suggested. Key points • Clinical characteristics of 222 adult patients in Japan with coronavirus disease 19 (COVID-19) and pre-existing rheumatic diseases were described. • Most patients were hospitalised (86.9%) for COVID-19 in Japan, 43.3% received oxygen, and 9.0% died. • The COVID-19 characteristics of patients with rheumatic diseases did not show any obvious different pattern from those of the general population in Japan. • In this study, older age (≥ 65 years), corticosteroid use, comorbid diabetes, and lung diseases are associated with higher risk for severe COVID-19 progression.

Soluble CD13 induces inflammatory arthritis by activating the bradykinin receptor B1

CD13, an ectoenzyme on myeloid and stromal cells, also circulates as a shed, soluble protein (sCD13) with powerful chemoattractant, angiogenic, and arthritogenic properties, which require engagement of a G protein-coupled receptor (GPCR). Here we identify the GPCR that mediates sCD13 arthritogenic actions as the bradykinin receptor B1 (B1R). Immunofluorescence and immunoblotting verified high expression of B1R in rheumatoid arthritis (RA) synovial tissue and fibroblast-like synoviocytes (FLSs), and demonstrated binding of sCD13 to B1R. Chemotaxis, and phosphorylation of Erk1/2, induced by sCD13, were inhibited by B1R antagonists. In ex vivo RA synovial tissue organ cultures, a B1R antagonist reduced secretion of inflammatory cytokines. Several mouse arthritis models, including serum transfer, antigen-induced, and local innate immune stimulation arthritis models, were attenuated in Cd13-/- and B1R-/- mice and were alleviated by B1R antagonism. These results establish a CD13/B1R axis in the pathogenesis of inflammatory arthritis and identify B1R as a compelling therapeutic target in RA and potentially other inflammatory diseases.

Inhibition of histone readers bromodomain extra-terminal proteins alleviates skin fibrosis in experimental models of scleroderma

Binding of the bromodomain and extraterminal domain proteins (BETs) to acetylated histone residues is critical for gene transcription. We sought to determine the antifibrotic efficacy and potential mechanisms of BET inhibition in systemic sclerosis (SSc). Blockade of BETs was done using a pan-BET inhibitor, JQ1; BRD2 inhibitor, BIC1; or BRD4 inhibitors AZD5153 or ARV825. BET inhibition, specifically BRD4 blockade, showed antifibrotic effects in an animal model of SSc and in patient-derived diffuse cutaneous SSc (dcSSc) fibroblasts. Transcriptome analysis of JQ1-treated dcSSc fibroblasts revealed differentially expressed genes related to extracellular matrix, cell cycle, and calcium (Ca²⁺) signaling. The antifibrotic effect of BRD4 inhibition was mediated at least in part by downregulation of Ca²⁺/calmodulin–dependent protein kinase II α and reduction of intracellular Ca²⁺ concentrations. On the basis of these results, we propose targeting Ca²⁺ pathways or BRD4 as potentially novel therapeutic approaches for progressive tissue fibrosis.

CX3CL1/fractalkine regulates the differentiation of human peripheral blood monocytes and monocyte-derived dendritic cells into osteoclasts

Osteoclast differentiation is promoted under inflammatory conditions and osteoclasts play a major role in bone destruction in rheumatoid arthritis (RA). Chemokine (C-X3-C motif) ligand 1 (CX3CL1), also known as fractalkine, functions as a chemoattractant and adhesion molecule, and is involved in the pathogenesis of RA. The blockade of CX3CL1 inhibits the migration of macrophages and osteoclast precursor cells into the inflamed synovium. In the present study, we investigated the direct stimulatory effects of CX3CL1 on osteoclast differentiation from human peripheral blood monocytes and monocyte-derived dendritic cells. A stimulation with CX3CL1 significantly promoted osteoclast differentiation from CD16^- monocytes and also monocyte-derived dendritic cells induced by macrophage colony-stimulating factor (M-CSF) and receptor activator of NF-κB ligand (RANKL). On the other hand, CD16⁺ monocytes treated with M-CSF and RANKL did not differentiate into osteoclasts, even with CX3CL1. Calcium resorption was significantly increased by monocyte-derived osteoclasts, but not by dendritic cell-derived osteoclasts, following the addition of CX3CL1. The present results suggest that CX3CL1 directly regulates osteoclast differentiation. CX3CL1 may play important roles in the pathogenesis of RA, not only through the accumulation of inflammatory cells, but also through osteoclastogenesis.

Treatment with an Anti-CX3CL1 Antibody Suppresses M1 Macrophage Infiltration in Interstitial Lung Disease in SKG Mice

CX3C Motif Chemokine Ligand 1 (CX3CL1; fractalkine) has been implicated in the pathogenesis of rheumatoid arthritis (RA) and its inhibition was found to attenuate arthritis in mice as well as in a clinical trial. Therefore, we investigated the effects of an anti-CX3CL1 monoclonal antibody (mAb) on immune-mediated interstitial lung disease (ILD) in SKG mice, which exhibit similar pathological and clinical features to human RA-ILD. CX3CL1 and CX3C chemokine receptor 1 (CX3CR1), the receptor for CX3CL1, were both expressed in the fibroblastic foci of lung tissue and the number of bronchoalveolar fluid (BALF) cells was elevated in ILD in SKG mice. No significant changes were observed in lung fibrosis or the number of BALF cells by the treatment with anti-CX3CL1 mAb. However, significantly greater reductions were observed in the number of M1 macrophages than in M2 macrophages in the BALF of treated mice. Furthermore, CX3CR1 expression levels were significantly higher in M1 macrophages than in M2 macrophages. These results suggest the stronger inhibitory effects of the anti-CX3CL1 mAb treatment against the alveolar infiltration of M1 macrophages than M2 macrophages in ILD in SKG mice. Thus, the CX3CL1-CX3CR1 axis may be involved in the infiltration of inflammatory M1 macrophages in RA-ILD.

New Assay System Elecsys Anti-p53 to Detect Serum Anti-p53 Antibodies in Esophageal Cancer Patients and Colorectal Cancer Patients: Multi-institutional Study

BACKGROUND

Several recent studies suggest that serum anti-p53 antibodies (s-p53-Abs) may be combined with other markers to detect esophageal and colorectal cancer. In this study, we assessed the sensitivity and specificity of s-p53-Abs detection of a new electrochemiluminescence immunoassay (ECLIA; Elecsys anti-p53).

METHODS

Elecsys anti-p53 assay was used to analyze the level of s-p53-Abs in blood sera from patients with esophageal or colorectal cancer taken before treatment. Control blood sera from healthy volunteers, patients with benign diseases, and patients with autoimmune diseases served as a reference. In addition, squamous cell carcinoma antigen (SCC-Ag) and cytokeratin 19 fragments (CYFRA21-1) were assessed in patients with esophageal cancer, and carcinoembryonic antigen (CEA) and carbohydrate antigen (CA) 19-9 were assessed in patients with colorectal cancer.

RESULTS

Samples from 281 patients with esophageal cancer, 232 patients with colorectal cancer, and 532 controls were included in the study. The median value of s-p53-Abs in control samples was < 0.02 μg/mL (range < 0.02-29.2 μg/mL). Assuming 98% specificity, the cut-off value was determined as 0.05 μg/mL. s-p53-Abs were detected in 20% (57/281) of patients with esophageal cancer and 18% (42/232) of patients with colorectal cancer. In combination with SCC-Ag and CEA, respectively, s-p53-Abs detected 51% (144/281) of patients with esophageal and 53% (124/232) of patients with colorectal cancer.

CONCLUSIONS

The new s-p53-Abs assay Elecsys anti-p53 was useful in detecting esophageal and colorectal cancers with high specificity. Adding s-p53-Abs to conventional markers significantly improved the overall detection rates.

SAT0116 COMPARISON OF THE EFFICACY OF ABATACEPT ON ELDERLY AND YOUNG PATIENTS WITH RHEUMATOID ARTHRITIS

Background:

The widespread use of biologic agents has greatly improved the prognosis of rheumatoid arthritis (RA). On the other hand, elderly patients with RA are relatively increasing. Although achieving low disease activity is a goal for those elderly patients as well as young patients, the efficacy of tumor necrosis factor inhibitors were reported to be equally or slightly less effective in elderly patients than in young patients. There is a lack of evidence for the efficacy of abatacept (ABT) in elderly patients.

Objectives:

In this study, we aimed to clarify the efficacy of ABT in elderly and young patients with RA compared to csDMARDs.

Methods:

This is a multicenter, open-label, prospective, observational study. All patients with RA enrolled this study are refractory to csDMARDs and have not received any biologics. Either ABT or csDMARDs was administered at the discretion of physicians to elderly (65 years and older) and young (20-64 years) patients (ABT-elderly, ABT-young, control (CTL)-elderly, and CTL-young groups). Comparison was made between 4 groups of patients. The primary study endpoint was a good response by EULAR response criteria at week 24 after administration. The research procedure has been approved by the ethics committee of Toho University School of Medicine (Approval number: A17112).

Results:

A total of 219 patients, 127 in the ABT group and 92 in the CTL group, were enrolled in this study. The majority of patients were women (82.7%) with a mean age (±SD) of 64.9±13.6 years (74.5±5.9 years in the elderly group and 52.4±10.1 years in the young group). The ABT group had higher disease activity, higher HAQ, and higher steroid use rates and dosage than the CTL group. These were also observed in the elderly group. In the young group, although the ABT group had higher disease activity and higher HAQ than the CTL group, no difference was observed in steroid use rates and dosage. The ABT group more frequently achieved a good response by EULAR response criteria compared to the CTL group at week 24 (58.8% and 27.2%, respectively, p<0.0001). The ABT group also showed higher efficacy than the CTL group in the elderly and young groups with a good response. Regarding the improvement in DAS28-ESR and DAS28-CRP, the ABT group was also superior to the CTL group. There was no difference on efficacy between elderly and young patients from the ABT groups.

Based on propensity score matching for disease activity at baseline, 61 matched pairs of patients treated with ABT or csDMARDs were statistically extracted. Although there was no significant difference in the rate of patients with a good response by EULAR response criteria between the ABT and the CTL groups, the ABT group showed significantly better response than the CTL group in the elderly. Furthermore, the ABT group was superior to the CTL group in improvement in both DAS28-ESR and DAS28-CRP, and similar results were obtained in the elderly. However, there was no significant difference between the ABT group and the CTL group in the young. In addition, elderly patients had significant improvement in DAS28-ESR compared with young patients in the ABT group.

Conclusion:

Treatment with ABT showed higher efficacy compared with CTL, particularly in elderly patients with RA.

References:

[1]Harigai M, et al. Mod Rheumatol. 2019;29:747.

[2]Sugihara T, Harigai M. Drugs Aging. 2016;33:97.

Disclosure of Interests:

Sei Muraoka Consultant of: Asahikasei Pharma Corp., Speakers bureau: Ono Pharmaceutical Co., Ltd., Eisai Co., Ltd., Asahikasei Pharma Corp., and Astellas Pharma Inc., Zento Yamada: None declared, Wataru Hirose: None declared, Hajime Kono: None declared, Shinsuke Yasuda Speakers bureau: Bristol Myers Squibb, Chugai Pharmaceutical Co., Tanabe Mitsubishi Parma Co., and GlaxoSmith Kline, Toshihiro Nanki Grant/research support from: Chugai Pharmaceutical Co., Eisai Co., Ltd., Teijin Pharma Ltd., Eli Lilly Japan K.K., Bristol-Myers K.K., Ono Pharmaceutical Co., Ltd., Novartis Pharma K.K., Asahikasei Pharma Corp., Mitsubishi-Tanabe Pharma Co., Astellas Pharma Inc., Ayumi Pharmaceutical Co., Pfizer Japan Inc., Daiichi Sankyo Co., Ltd., Shionogi & Co., Ltd., Sanofi K.K., Nippon Kayaku Co., Ltd., Yutoku Pharmaceutical Ind. Co., Ltd., UCB Japan Co. Ltd., Nihon Pharmaceutical Co., Ltd., and Bayer Yakuhin, Ltd., Consultant of: UCB Japan Co., Ltd., Eisai Co., Ltd., and Chugai Pharmaceutical Co., Speakers bureau: Mitsubishi-Tanabe Pharma Co., Chugai Pharmaceutical Co., Eisai Co., Ltd., Astellas Pharma Inc., Janssen Pharmaceutical K.K., Ayumi Pharmaceutical Co., Pfizer Japan Inc., Asahikasei Pharma Corp., Sanofi K.K., Novartis Pharma K.K., Eli Lilly Japan K.K., Nippon Kayaku Co., Ltd., Teijin Pharma Ltd., Takeda Pharmaceutical Co., Nippon Boehringer Ingelheim Co., Ltd., and AbbVie GK.

Rationale for and clinical development of anti-fractalkine antibody in rheumatic diseases

Introduction: Rheumatic diseases are inflammatory diseases that damage target organs via multiple subsets of immune cells. Fractalkine (FKN) acts as chemoattractant as well as adhesion molecule. It contributes to the pathogenesis of rheumatoid arthritis (RA) and other rheumatic diseases through multiple mechanisms: the migration of monocytes and cytotoxic effector T cells, the proliferation and activation of fibroblast-like synoviocytes, angiogenesis, and osteoclastogenesis. FKN has potential as a new therapeutic target, and clinical trials on anti-FKN monoclonal antibodies for RA are ongoing. FKN-targeted therapy has been developed and a humanized anti-FKN monoclonal antibody is currently being tested in phase 2 clinical trials. Areas covered: This review summarizes accumulated evidence on the involvement of FKN in RA and other rheumatic diseases, including systemic lupus erythematosus (SLE), systemic sclerosis, inflammatory myositis, Sjögren's syndrome (SS), osteoarthritis, and systemic vasculitis. Expert opinion: A phase 1/2a clinical trial on anti-FKN demonstrated its safety, tolerability, and clinical efficacy. Anti-FKN therapy has potential in the treatment of atherosclerosis and interstitial lung diseases associated with RA. Based on recent findings, other rheumatic diseases, including SLE, polymyositis/dermatomyositis, and SS, may also be treated using anti-FKN therapy.

Successful Treatment of IgA Vasculitis Complicated with Bowel Perforation and Crescentic Glomerulonephritis by Combination Therapy of Glucocorticoid, Cyclosporine and Factor XIII Replacement

We report the findings of an 18-year-old boy with immunoglobulin A vasculitis (IgAV) complicated with bowel perforation and nephritis. He presented with abdominal pain, arthralgia and palpable purpura. Massive proteinuria developed during his clinical course. The patient was treated successfully using combination therapy of glucocorticoid (GC), cyclosporine (CYA) and factor XIII (F XIII) replacement. A standard treatment strategy for severe IgAV patients has not been established due to its rarity. Combination therapy using GC, CYA and F XIII replacement should be considered for severe IgAV patients.

Resistin upregulates chemokine production by fibroblast-like synoviocytes from patients with rheumatoid arthritis

Background

Adipokines are bioactive hormones secreted by adipose tissues. Resistin, an adipokine, plays important roles in the regulation of insulin resistance and inflammation. Resistin levels are known to be increased in the serum and synovial fluid of rheumatoid arthritis (RA) patients. However, the pathogenic role of resistin in RA has not yet been elucidated.

Methods

The expression of resistin and adenylate cyclase-associated protein 1 (CAP1), a receptor for resistin, was examined immunohistochemically in synovial tissue. CAP1 expression in in vitro cultured fibroblast-like synoviocytes (FLSs) was assessed with a reverse transcription-polymerase chain reaction (PCR) and western blotting. The gene expression of resistin-stimulated FLSs was evaluated by RNA sequencing (RNA-Seq) and quantitative real-time PCR. Concentrations of chemokine (C-X-C motif) ligand (CXCL) 8, chemokine (C-C motif) ligand (CCL) 2, interleukin (IL)-1β, IL-6 and IL-32 in culture supernatants were measured by enzyme-linked immunosorbent assay. Small interfering RNA (siRNA) for CAP1 was transfected into FLSs in order to examine inhibitory effects.

Results

The expression of resistin and CAP1 in synovial tissue was stronger in RA than in osteoarthritis (OA). Resistin was expressed by macrophages in the RA synovium, while CAP1 was expressed by macrophages, FLSs and endothelial cells. In vitro cultured RA FLSs also expressed CAP1. RNA-Seq revealed that the expression levels of 18 molecules were more than twofold higher in resistin-stimulated FLSs than in unstimulated FLSs. Seven chemokines, CXCL1, CXCL2, CXCL3, CXCL5, CXCL6, CXCL8, and CCL2, were included among the 18 molecules. Increases induced in the expression of CXCL1, CXCL8, and CCL2 by the resistin stimulation were confirmed by real-time PCR. The stimulation with resistin increased the protein levels of CXCL8 and CCL2 produced by RA FLSs, and the upregulated expression of CXCL8 was inhibited by the abrogation of CAP1 by siRNA for CAP1. Production of IL-6 by FLSs was also increased by resistin. Expression of IL-1β and IL-32 was not detected by ELISA.

Conclusions

Resistin contributes to the pathogenesis of RA by increasing chemokine production by FLSs via CAP1 in synovial tissue.

Leptin stimulates interleukin-6 production via janus kinase 2/signal transducer and activator of transcription 3 in rheumatoid synovial fibroblasts

OBJECTIVES

The aim of this study was to determine the influence of leptin on the production of proinflammatory cytokines by rheumatoid synovial fibroblasts (RSFs).

METHODS

Synovial tissue was obtained from patients with rheumatoid arthritis (RA). Leptin receptor mRNAs were detected by reverse transcription-polymerase chain reaction (RT-PCR). Productions of mRNA and protein of interleukin (IL)-1β, tumour necrosis factor-α (TNF-α), and IL-6 in the culture medium were detected by real-time PCR and ELISA kit, respectively. Small interfering RNA (siRNA) was transfected into RSF to down-regulate the expression of leptin receptor. Effects of inhibitors of janus kinase 2 (JAK2), phosphatidylinositol 3-kinase (PI3K), and mitogen-activated protein kinase (MAPK) on IL-6 production were evaluated. Phosphorylation of signal transducer and activator of transcription 3 (STAT3) in RSF were determined by Western blot analysis.

RESULTS

We detected leptin receptor mRNAs in RSFs. Expression of IL-1β and IL-6 mRNA was enhanced in a concentration-dependent manner by addition of leptin to RSFs. IL-6 secretion by RSFs showed an increase after leptin stimulation. Leptin-induced production of IL-6 by RSFs was decreased after exposure to siRNA targeting leptin receptor (Ob-Rb). A JAK2 inhibitor, but not PI3K and MAPK inhibitors, decreased leptin-induced IL-6 production. Enhanced phosphorylation of STAT3 was observed in RSFs after stimulation by leptin.

CONCLUSIONS

Leptin may be one of the proinflammatory cytokines that up-regulates IL-6 production in RSFs via activation of JAK2/STAT3. Leptin and JAK/STAT pathway may represent a new alternative therapeutic target in the treatment of RA.

Microstructure of Simulated High-Level Waste Glass Doped with Short-Lived Actinides, 238Pu and 244Cm

The microstructural changes of a simulated waste glass irradiated with doping of 238pu and 244Cm were observed by use of a preshadowed carbon replica technique in combination with scanning electron microscopy (SEM). The irradiated glass was annealed and its microstructural changes after annealing were observed by use of the sametechnique.

In the glass irradiated at a dose of 2.75x1025 α-decays/m3, bubbles with a radius from 0.15μrm to 0.35μm were observed. The average bubble radius and the bubble density were 0.23μm and 1x1017 bubbles/m3, respectively. Using these observed values, the volume change of the glass resulting from the bubble formation was estimated to be + 0.51 %. This valuoof + 0.51 % was close to the volume change of the irradiated glass measured in our previous study, which suggests a large portion of the volume change by α-irradiation results from bubble formation. In the glass annealed after irradiation the average bubbleradius was observed to decrease with annealing time. The bubble radius as a function of annealing time was analyzed on the basis of the helium diffusion model with two chemicalprocesses, i.e. trapping at bubbles and re-solution from bubbles into glass matrix. The values of the diffusion coefficient of helium, the trapping parameter and the re-solution parameter, which had been obtained experimentally in our previous study on the helium release, were applied to the calculation. The calculated curve was in good agreement with the observed data.

Systemic lupus erythematosus complicated by recurrent pneumothorax: Case report and literature review

Pneumothorax is a rare pleuropulmonary manifestation of systemic lupus erythematosus. We encountered a 37-year-old Japanese woman who had systemic lupus erythematosus complicated by recurrent pneumothorax during treatment for recurrent serositis with glucocorticoid therapy. She was admitted for the third episode of lupus peritonitis in December 2005. Intravenous cyclophoshamide and increased dose of oral prednisolone were administered. In early January 2006, hemoptysis was observed and bronchofiberscopy revealed hemorrhage from the left lower lobe. After intravenous methylprednisolone pulse therapy and oral cyclosporine therapy were added, pleurisy and pulmonary hemorrhage improved. On February 22nd, she suddenly developed pneumothorax on the right side, followed by pneumothorax on the left side after 2 days. This pneumothorax on the left side did not improve despite chest tube drainage for over one month. She underwent thoracoscopic partial lobectomy of lower lobe of the left lung, and her symptoms improved. Review of the literature identified 10 case reports of systemic lupus erythematosus complicated by pneumothorax. All of the patients including our case had underlying pulmonary lesions, and 9/11 patients had pleurisy. Besides 10/11 patients received glucocorticoid therapy before the occurrence of pneumothorax. Tissue fragility caused by these factors might contribute to the complication of pneumothorax in patients with systemic lupus erythematosus.

Pharmacokinetic study and Fcgamma receptor gene analysis in two patients with rheumatoid arthritis controlled by low-dose infliximab

The main aim of this study is to investigate the pharmacokinetics of infliximab and Fcgamma receptor (FcgammaR) polymorphism in two patients with rheumatoid arthritis (RA) who were well controlled by low-dose infliximab. A 57-year-old woman (Patient 1) and a 67-year-old woman (Patient 2) had active RA despite methotrexate and prednisolone treatments. They improved after the addition of infliximab (3 mg/kg), but developed pneumonia and sepsis, respectively. Although the infliximab doses were reduced to 1.5 mg/kg and 1 mg/kg, respectively, clinical improvements were maintained. Blood samples were obtained at 1 h after infliximab administration and at eight weeks (just before the next dose). The elimination half-life was determined by the serum concentration of infliximab. We also analyzed the polymorphisms of FcgammaRIIA, FcgammaRIIIA, and FcgammaRIIIB for the genomic DNA samples from the two patients and three controls. Amplification of the FcgammaR-genomic regions in allotype-specific polymerase chain reactions was used to distinguish the genotypes. Decresed clearance of infliximab was proven by a pharmacokinetic study of these patients under low-dose infliximab therapy. 131H/H (FcgammaRIIA) and 176F/F (FcgammaRIIIA) were detected in both patients. NA1/NA2 and NA2/NA2 (FcgammaRIIIB) were detected in Patients 1 and 2, respectively. These patients were well controlled over the long term by low-dose infliximab. The mechanism of the reduced clearance of infliximab might possibly be explained in part by the FcgammaR polymorphisms.

[Case of pulmonary aspergillosis associated with inappropriate antidiuretic hormone syndrome caused by voriconazole therapy]

A 75-year-old man presented with hemoptysis. Consolidation was identified in the left lower lobe around multiple bullae. He was found to have chronic necrotizing pulmonary aspergillosis based on a high titer of aspergillus antigen and positive antibody. He was treated with 400 mg/day voriconazole. However, liver dysfunction and hyponatremia developed at 21 days after beginning administration of voriconazole. Serum sodium levels were 122 mEq/l. but urinary sodium showed a high level of 135 mEq/l. The serum sodium level improved 10 days after voriconazole was discontinued. Serum levels of voriconazole on day 15 were high at 18 microg/ml (safe effective serum level: 1.5 to 4.5 microg/ml). An analysis of genetic polymorphism showed a mutation of cytochrome P450 (CYP2C19*2 G681A). We report the first case of a voriconazole-induced syndrome of inappropriate antidiuretic hormone caused by a polymorphism mutation of cytochrome P450.

Inactivation of creatine kinase induced by quercetin with horseradish peroxidase and hydrogen peroxide. pro-oxidative and anti-oxidative actions of quercetin

Pro-oxidative and anti-oxidative actions of quercetin were examined through inactivation of CK and inhibition of lipid peroxidation. Quercetin induced inactivation of creatine kinase (CK) during the interaction with horseradish peroxidase and hydrogen peroxide (HRP-H(2)O(2)). CK activity in heart homogenate was also reduced by quercetin with HRP-H(2)O(2). Flavonoids that have a catechol structure in the B ring, such as taxifolin, catechin and luteolin, also induced CK inactivation. These flavonoids strongly inhibited NADPH and ADP-Fe(3+)-dependent microsomal lipid peroxidation. These results suggest a close relationship between pro-oxidative and anti-oxidative actions of quercetin. Electron spin resonance (ESR) signals of the quercetin radical was emitted during the interaction of quercetin with HRP-H(2)O(2) in the presence of Zn(2+) as a stabilizer. Adding CK diminished the ESR signals of quercetin radicals, suggesting CK efficiently scavenged quercetin radicals. Sulfhydryl groups and tryptophan residues in CK decreased during the interaction of quercetin with HRP-H(2)O(2). The kinetic parameters of K(m) and V(max) for ADP and creatine phosphate changed rapidly, suggesting that the inactivation of CK was induced through conformational change of the enzyme. Glyceraldehyde-3-phosphate dehydrogenase had a higher sensitivity to quercetin with HRP-H(2)O(2) than CK. Quercetin radicals may mediate between pro-oxidative and anti-oxidative action.

A developmentally regulated and psychostimulant-inducible novel rat gene mrt1 encoding PDZ-PX proteins isolated in the neocortex

Single or repeated exposure to psychostimulants such as amphetamines and cocaine after postnatal week 3 leads to an enduring enhancement in the psychotomimetic responses elicited by a subsequent challenge of a stimulant in rodents. This behavioral sensitization phenomenon has been considered to be the neural consequences of stimulant-induced alterations in gene expression in the brain after a critical period of postnatal development. Using a differential cloning technique, RNA arbitrarily primed PCR, we have now identified from the rat neocortex a novel and developmentally regulated methamphetamine (MAP)-inducible gene mrt1 (MAP responsive transcript 1). mrt1 encodes two major types of PDZ- and PX-domains containing proteins of approximately 62 kDa in size with different carboxy termini, Mrt1a and Mrt1b. The mrt1 mRNAs for Mrt1a, mrt1a, and for Mrt1b, mrt1b, are predominantly expressed in various brain regions and the testes, respectively. Acute MAP injection upregulated mrt1b expression in the neocortex after postnatal week 3 in a D1 receptor antagonist-sensitive manner without affecting mrt1a expression. This upregulation was mimicked by another stimulant, cocaine, whereas pentobarbital and D1 antagonist failed to change the mrt1b transcript levels. Moreover, repeated daily treatment of MAP, but not MAP plus D1 antagonist, for 5 days caused an augmentation of the basal expression of mrt1b 2 and 3 weeks after the drug discontinuation. These late-developing, cocaine-crossreactive, D1 antagonist-sensitive and long-term regulations of mrt1b by MAP are similar to the pharmacological profiles of stimulant-induced behavioral sensitization, and therefore may be associated with the initiation and/or maintenance of the long-term neuronal adaptation.

Pseudoankylosis of the mandible as a result of methyl methacrylate-induced inflammatory cicatricial contracture of the temporal muscle after cranioplasty

Pseudoankylosis of the mandible after intracranial surgical procedure has been widely reported, and is usually caused by fibrosis of the temporal muscle as a result of injury during the operation. We present an unusual case of mandibular pseudoankylosis as a result of methyl methacrylate-induced aseptic inflammatory cicatricial contracture of the temporal muscle after cranioplasty.

Amatoxin poisoning from ingestion of Japanese Galerina mushrooms

BACKGROUND

Although some Japanese Galerina species poisonings manifest as gastrointestinal symptoms followed by late-onset hepatorenal failure (phalloides syndrome), the toxin responsible for this has not been determined.

CASE REPORT

We report a 6-year-old boy who developed characteristic cholera-like diarrhea and late-onset severe hepatic deterioration after eating mushrooms, later identified as a Galerina species, most likely Galerina fasciculata. A residual mushroom revealed alpha-amanitin. This account is the first known reported case of poisoning by Japanese Galerina species where an amatoxin was demonstrated to be responsible for the toxicity.

Immunostimulatory effects of the muramyl dipeptide analogue LK415 in chickens immunized with a vaccine strain of infectious bursal disease virus

The effects of muramyl dipeptide (MDP) synthetic analogue LK415 on the immune response of chickens immunized with a live vaccine against infectious bursal disease (IBD) were studied in two independent trials, using levamisole hydrochloride as comparative immunostimulant. Groups of five-week-old commercial chickens (Isa Brown) were immunized orally with 10 doses of the vaccine strain of IBDV (Winterfield strain). The chickens were then given four injections of the MDP analogue LK415 in a dosage of either 0.25 mg/kg body weight (b.w.) or 2.5 mg/kg b.w. or levamisole at a daily dose of 15 mg/kg b.w. for four consecutive days, starting from the day of immunization. Histological examinations of bursal tissue collected on days 2, 4 and 7 postimmunization (p.i.) showed a lower degree of destruction of bursal follicles and earlier renewal of bursal tissue in LK415-treated chickens compared to levamisole-treated and untreated immunized groups. Compared to the other groups, the LK415-treated chickens showed a significantly higher antibody response to IBDV on days 14 and 28 p.i. (P < 0.01) as measured by commercial ELISA. The present study indicates some potent immunostimulatory effects of the MDP analogue LK415 on the chicken immune system.

Forced swimming stimulates the expression of vasopressin and oxytocin in magnocellular neurons of the rat hypothalamic paraventricular nucleus

Previous studies have shown that a 10-min forced swimming session triggers the release of both vasopressin and oxytocin into the extracellular fluid of the hypothalamic paraventricular (PVN) and supraoptic nuclei (SON) in rats. At the same time oxytocin, but not vasopressin, was released from the axon terminals into the blood. Here we combined forced swimming with in situ hybridization to investigate whether (i) the stressor-induced release of vasopressin and oxytocin within the PVN originates from parvo- or magnocellular neurons of the nucleus, and (ii) central release with or without concomitant peripheral secretion is followed by changes in the synthesis of vasopressin and/or oxytocin. Adult male Wistar rats were killed 2, 4 or 8 h after a 10-min forced swimming session and their brains processed for in situ hybridization using 35S-labelled oligonucleotide probes. As measured on photo-emulsion-coated slides, cellular vasopressin mRNA concentration increased in magnocellular PVN neurons 2 and 4 h after swimming (P < 0.05). Similarly, oxytocin mRNA concentration was significantly increased in magnocellular neurons of the PVN at 2 and 8 h (P < 0.05). We failed to observe significant effects on vasopressin and oxytocin mRNA levels in the parvocellular PVN and in the SON. Taken together with results from previous studies, our data suggest that magnocellular neurons are the predominant source of vasopressin and oxytocin released within PVN in response to forced swimming. Furthermore, in the case of vasopressin, central release in the absence of peripheral secretion is followed by increased mRNA levels, implying a refill of depleted somato-dendritic vasopressin stores. Within the SON, however, mRNA levels are poor indicators of the secretory activity of magnocellular neurons during stress.

Inactivation of creatine kinase during the interaction of indomethacin with horseradish peroxidase and hydrogen peroxide: involvement of indomethacin radicals

Creatine kinase (CK) was used as a marker molecule to examine the side effect of damage to tissues by indomethacin (IM), an effective drug to treat rheumatoid arthritis and gout, with horseradish peroxidase and hydrogen peroxide (HRP-H2O2). IM inactivated CK during its interaction with HRP-H2O2. Under aerobic conditions, inactivation of CK significantly decreased. CK in rat heart homogenate was also inactivated by IM with HRP-H2O2. When IM was incubated with HRP-H2O2, the maximum absorption of IM at 280 nm rapidly decreased and a new peak at 410 nm occurred with isosbestic points at 260 and 312 nm. In contrast, under anaerobic conditions, the spectral change of IM was almost absent, indicating IM was oxidized to the yellow substance by HRP-H2O2. Adding catalase strongly inhibited the production of yellow substance. Sodium azide also blocked the formation of yellow substance and the inactivation of CK. Electron spin resonance signals of IM carbon-centered radical were detected using 2-methyl-2-nitrosopropane during the interaction of IM with HRP-H2O2 under anaerobic conditions. Oxygen was consumed during the interaction of IM with HRP-H2O2. These results suggest that IM carbon-centered radicals may rapidly react with O2 to generate the peroxyl radicals. Sulfhydryl groups and tryptophane residues of CK decreased during the interaction of IM with HRP-H2O2. Other sulfhydryl enzymes, including alcohol dehydrogenase and glyceraldehyde-3-phosphate dehydrogenase, were also readily inactivated during the interaction with HRP-H2O2. Sulfhydryl enzymes seem to be very sensitive to IM activated by HRP-H2O2.

Incidence of deep fascial space infection after surgical removal of the mandibular third molars

Nine hundred and ninety-three patients who underwent surgical removal of the mandibular third molars with oral antibiotic prophylaxis were examined to determine the incidence of postoperative deep fascial space infection and its background factors. Postoperative deep fascial space infection was observed in 8 of the patients (0.8%; 4 males and 4 females), and submandibular spaces were involved in all infected patients. Only 1 of these 8 patients was an immune compromised host. Patients aged 30 years or more had a significantly higher incidence of deep fascial space infection than those aged under 30. Five patients had partial bony impactions and 3 had complete bony impactions. However, the incidence of infection according to the molar positions was not significantly different between partial bony impaction and complete bony impaction. The 8 patients had not had pericoronitis preoperatively. The clinical courses of all were favorable after antibiotics were administered intravenously. In conclusion, the incidence of deep fascial space infection after removal of the mandibular third molars was low, at 0.8%. However, it may be desirable to remove the molars, if applicable, at a younger age because of the higher incidence of infection in patients aged over 30. The results of this study also offer information that will be useful as a basis for obtaining informed consent from patients whose mandibular third molars are to be removed.

Phenylbutazone radicals inactivate creatine kinase

Creatine kinase (CK) was used as a marker molecule to examine the side effect of damage to tissues by phenylbutazone (PB), an effective drug to treat rheumatic and arthritic diseases, with horseradish peroxidase and hydrogen peroxide (HRP-H(2)O2). PB inactivated CK during its interaction with HRP-H(2) O(2), and inactivated CK in rat heart homogenate. PB carbon-centered radicals were formed during the interaction of PB with HRP-H(2)O2. The CK efficiently reduced electron spin resonance signals of the PB carbon-centered radicals. The spin trap agent 2-methyl-2-nitrosopropane strongly prevented CK inactivation. These results show that CK was inactivated through interaction with PB carbon-centered radicals. Sulfhydryl groups and tryptophan residues in CK were lost during the interaction of PB with HRP-H(2)O2, suggesting that cysteine and tryptophan residues are oxidized by PB carbon-centered radicals. Other enzymes, including alcohol dehydrogenase, glyceraldehyde-3-phosphate dehydrogenase, but not lactate dehydrogenase, were also inactivated. Sulfhydryl enzymes seem to be sensitive to attack by PB carbon-centered radicals. Inhibition of SH enzymes may explain some of the deleterious effects induced by PB.

Specific characteristics and management strategies of cerebral artery aneurysms: report of eleven cases

Owing to the deep location of the posterior cerebral artery (PCA) and its close relationship with the brainstem and surrounding vital structures, surgical treatment of aneurysms in this region is complex. This study was undertaken in an attempt to better delineate the surgical risks of PCA aneurysms. A retrospective analysis was undertaken in 11 patients with PCA aneurysm surgically treated between 1988 and 1996 at Shinshu University and its affiliated hospitals. Data regarding surgical strategy, surgical complications and outcomes were analysed. Seven aneurysms were saccular (including one mycotic) and the other four were fusiform, dissecting, thrombosed and an infundibular dilatation. The locations of the aneurysms were at the P1 segment in two patients, P1-P2 junction in two, P2 segment in six and P3 segment in one. Six saccular non-mycotic aneurysms were treated with neck clipping and the other five aneurysms were treated each with proximal occlusion of the parent artery, excision of the aneurysm or wrapping. All aneurysms were satisfactorily exposed except one large saccular aneurysm. Surgical outcomes were either good recovery or moderate disability in 10 patients, and severe disability in one patient with a large aneurysm due to temporal lobe contusion. In conclusion it is the responsibility of the surgeon dealing with rare PCA aneurysms to be aware of these specific characteristics and to appreciate which surgical technique is appropriate for each patient.

DNA strand break and 8-hydroxyguanine formation induced by 2-hydroxyestradiol dispersed in liposomes

DNA damage induced by estrogens dispersed in liposomes was investigated. 2-Hydroxyestradiol (2HOE(2)) and 4-hydroxyestradiol (4HOE(2)), but not estrone, estradiol-17beta or estriol, caused strand break of plasmid DNA damage in the presence of ADP-Fe(3+). The catechol structure may be necessary for DNA damage. When DNA was incubated with 2HOE(2) for a long time (24 h), DNA damage was induced even at very low concentrations. Adding hydrogen peroxide markedly enhanced the sensitivity of DNA to the attack by 2HOE(2). Hydroxyl radical (HO.) scavengers strongly inhibited the 2HOE(2)-induced DNA damage, and EDTA partially inhibited DNA damage. However, 2HOE(2) caused 8-hydroxyguanine formation from calf thymus DNA only in the presence of EDTA-Fe(3+), but not ADP-Fe(3+). In addition, deoxyribose, which is a detective molecule of HO(.), was not degraded by 2HOE(2) in the presence of ADP-Fe(3+). Upon adding EDTA 2HOE(2) rapidly degraded deoxyribose. These results suggest that DNA strand break caused by 2HOE(2) in the presence of ADP-Fe(3+) was due to ferryl ion rather than HO(.), whereas 8-hydroxyguanine (8HOG) induced by 2HOE(2) in the presence of EDTA-Fe(3+) was due to HO(.).

Strategic embolisation for successful resection of a large cerebral arteriovenous malformation

The risks accompanied by the treatment of cerebral arteriovenous malformation (AVM) are still cumulative despite recent progress in available treatment options. Pre-operative embolisation is one such option, however, it seldom makes the surgical resection difficult. The excessive embolised nidus makes the surgical resection difficult because it cannot be compressed during the resection surgery and embolised nidus as a 'glue ball' with marginal hypervascular territory is most difficult to remove. The aim of pre-operative embolisation for successful surgical resection is to put glue into the marginal part of the nidus so as to make a cleavage between the surrounding normal tissues. Remaining feedings via the dilatated leptomeningeal anastomoses from surrounding normal cortical arteries do not interfere with the resection and can be eliminated easily by coagulating the pia matter around the nidus. Strategic planning with regard to the systemic course of treatment, including the manner of resection, is important for effective pre-operative embolisation.

Iron-deficiency anemia associated with Helicobacter pylori gastritis

BACKGROUND

Recent studies have suggested an association of Helicobacter pylori and iron-deficiency anemia (IDA). This is a report of six cases of IDA associated with H. pylori gastritis.

METHODS

Six patients with IDA were studied (5 boys and 1 girl; mean age 13.6 years; range 13-15 years). Five had a medical history of long-standing IDA and of oral iron supplementation at outpatient clinics. The anemia recurred after the iron therapy had been discontinued. The sixth patient was admitted to the hospital with severe IDA. An extensive work-up was ordered that included technetium-99m (99mTc) scans for Meckel's diverticulum, total colonoscopy, and gastrointestinal endoscopy. After biopsy-based H. pylori test results were confirmed to be positive, anti-H. pylori therapy consisting of lansoprazole, clarithromycin, and metronidazole was administered for 2 weeks with no iron supplementation. The hematologic profile and iron status were assessed periodically after the end of the eradication regimen.

RESULTS

Upper gastrointestinal endoscopy revealed a marked antral nodularity but no evidence of bleeding lesions in all the patients. Given the histology and the fact that rapid urease test results were positive, chronic active gastritis with H. pylori was diagnosed in all these cases. H. pylori was successfully eradicated in all the patients. There was no evidence of IDA in any of the follow-up examinations between 27 and 50 months after anti-H. pylori therapy.

CONCLUSIONS

H. pylori infection may be involved in cases of IDA of unknown origin, and the eradication of H. pylori can be associated with the resolution of anemia.

Inactivation of creatine kinase by Adriamycin during interaction with horseradish peroxidase

Oxidative damage of creatine kinase (CK) induced by Adriamycin((R)) (ADM) with peroxidase was investigated using horseradish peroxidase (HRP). ADM oxidatively inactivated CK during its interaction with HRP in the presence of H(2)O(2) (HRP-H(2)O(2)). The red color of ADM was lost during oxidation by HRP-H(2)O(2). Adding catalase stopped the color change of ADM induced by HRP-H(2)O(2), indicating that ADM was oxidized by HRP complex I or II. CK was inactivated readily, even when it was added to the reaction mixture containing colorless ADM. Some sulfhydryl groups of CK, which have an important role in its enzyme activity, were very sensitive to ADM activated by HRP-H(2)O(2), suggesting that inactivation of CK is due to oxidation of SH groups at the active center. Presumably, oxidative ADM quinone is involved dominantly in the inactivation of CK. Among the anthracycline drugs tested in this study, only ADM and epirubicin caused inactivation of CK and alcohol dehydrogenase and loss of the red color during oxidation by HRP-H(2)O(2).

Antioxidative and prooxidative action of stilbene derivatives

The effects of stilbene derivatives, including resveratrol, diethylstilboestrol and stilbene, as antioxidants or prooxidants were examined. Resveratrol and diethylstilboestrol, but not stilbene, strongly inhibited NADPH- and adenosine 5'-diphosphate (ADP)-Fe3+-dependent lipid peroxidation at the initial and propagation stages. In addition, phenolic stilbenes also inhibited ultraviolet light-induced lipid peroxidation. Resveratrol and diethylstilboestrol efficiently scavenged 2,2'-azobis-(2-amidinopropane)-dihydrochloride peroxyl radicals. However, 2,2'-diphenyl-p-picrylhydrazyl radicals were trapped only by resveratrol, but not by diethylstilboestrol. These results suggest that the inhibitory effect of phenolic stilbenes on lipid peroxidation was due to their scavenging ability of lipid peroxyl and/or carbon-cantered radicals. Resveratrol efficiently reduced ADP-Fe3+, but not EDTA-Fe3+. Stilbenes and diethylstilboestrol did not reduce either ADP-Fe3+ or EDTA-Fe3+. The strand breaks of DNA were stimulated during the interaction of resveratrol with ADP-Fe3+ in the presence of H2O2. These results suggest that phenolic stilbenes act as antioxidants of membrane lipids and that resveratrol has a prooxidative effect DNA damage during interaction with ADP-Fe3+ in the presence of H2O2.

DNA damage induced by catechol derivatives

We investigated the effect of catechol derivatives, including dopa, dopamine, adrenaline and noradrenaline, on DNA damage and the mechanisms of DNA strand breakage and formation of 8-hydroxyguanine (8HOG). The catechol derivatives caused strand breakage of plasmid DNA in the presence of ADP-Fe(3+). The DNA damage was prevented by catalase, mannitol and dimethylsulfoxide, suggesting hydroxyl radical (HO..)-like species are involved in the strand breakage of DNA. Iron chelators, such as desferrioxamine and bathophenanthroline, and reduced glutathione also inhibited the DNA damage. Deoxyribose, a molecule that is used to detect HO,, was not degraded by dopa in the presence of ADP-Fe(3+). By adding EDTA, however, dopa induced the marked deoxyribose degradation in the presence of ADP-Fe(3+), indicating that EDTA may extract iron from ADP-Fe(3+) to catalyze HO. formation by dopa. Thus, EDTA was a good catalyst for HO.-generation, whereas it did not promote the strand breakage of DNA. However, calf thymus DNA base damage, which was detected as 8-HOG formation, was caused by dopa in the presence of EDTA-Fe(3+), but not in the presence of ADP-Fe(3+). The 8HOG formation was also inhibited by catalase and HO. scavengers, indicating that HO&z.rad; was involved in the base damage. These results suggest that DNA strand breakage is due to ferryl species rather than HO., and that 8HOG formation is due to HO. rather than ferryl species.