Reactive nitrogen intermediates, antinuclear antibodies and copper-thionein in serum of patients with rheumatic diseases

Elevated production of interleukin-18 is associated with renal disease in patients with systemic lupus erythematosus

To investigate the production mechanism and proinflammatory role of the cytokine interleukin (IL-18) in lupus nephritis, we investigated the plasma concentrations of IL-18 and nitric oxide (NO) and the release of IL-18 and NO from mitogen-activated peripheral blood monomuclear cells (PBMC), in 35 SLE patients with renal disease (RSLE), 37 patients without renal disease (SLE) and 28 sex- and age-matched healthy control subjects (NC). IL-18 and NO concentrations were measured by ELISA and colourimetric non-enzymatic assay, respectively. Gene expressions of IL-18 and IL-18 receptor were analysed by RT-PCR. Plasma IL-18 and NO concentrations were significantly higher in RSLE than NC (both P < 0.01). Elevation of plasma IL-18 in RSLE correlated positively and significantly with SLE -disease activity index and plasma NO concentration (r = 0.623, P < 0.0001 and r = 0.455, P = 0.017, respectively), and the latter also showed a positive and significant correlation with plasma creatinine (r = 0.410, P = 0.034) and urea (r = 0.685, P < 0.0001). There was no significant difference in gene expressions of IL-18 and IL-18 receptor in PBMC among RSLE, SLE and NC. Percentage increase in culture supernatant IL-18 concentration was significantly higher in RSLE than SLE and NC (both P < 0.05). The basal NO release was significantly higher in RSLE than that in SLE and NC (both P < 0.005). IL-18 is therefore suggested to play a crucial role in the inflammatory processes of renal disease in SLE.

A new diagnostic method for chronic hepatitis, liver cirrhosis, and hepatocellular carcinoma based on serum metallothionein, copper, and zinc levels

Serum metal levels and their ratios are frequently reported to be good signals for diagnosing various diseases. These parameters are not always specific to the disease, however, it is necessary to use other serum parameters for an exact diagnosis. We examined whether the monitoring of these serum parameters such as metallothionein, copper, and zinc levels are useful in diagnosing hepatic disorders. Metallothionein levels of patients with liver cirrhosis and hepatocellular carcinoma were found to be significantly lower than those of patients with chronic hepatitis and those of controls. In contrast, copper levels of the patients with liver cirrhosis and hepatocellular carcinoma were significantly higher than those with chronic hepatitis and controls. Zinc levels of the patients with chronic hepatitis and hepatocellular carcinoma were lower than those of controls. Using these three parameters, we are introducing a new parameter, (Cu/Zn)/MT, by which we can discriminate between patients in the [control+miscellaneous diseases+chronic hepatitis] group and those in the [liver cirrhosis+hepatocellular carcinomal group. The new parameter does not, however, allow us to clearly distinguish between the liver cirrhosis and hepatocellular carcinoma groups. Multivariate discriminant analysis was found to be very useful, with combinations of two discriminant functions having been designed to discriminate both between chronic hepatitis and liver cirrhosis and between liver cirrhosis and hepatocellular carcinoma. This method recognizes the differences between hepatic disorder, including chronic hepatitis, liver cirrhosis, and hepatocellular carcinoma groups. On the basis of these results, we propose here that the diagnosis of hepatic disorders should be made based on a combination of three serum levels such as those of metallothionein, copper, and zinc.

In vivo manipulation of endogenous metallothionein with a monoclonal antibody enhances a T-dependent humoral immune response

Metallothionein (MT) is a small stress response protein that can be induced by exposure to heavy metal cations, oxidative stressors, and acute phase cytokines that mediate inflammation. In previous experiments, we have shown that exogenous MT can affect cell proliferation, macrophage and cytotoxic T lymphocyte function, and humoral immunity to T-dependent antigens. In the studies described here, we have explored the effect of a monoclonal anti-MT antibody (clone UC1MT) on the role that endogenous MT plays in the humoral immune response. In vivo injection of UC1MT significantly increased the humoral response to simultaneous challenge with ovalbumin (OVA). In contrast, mice immunized with OVA in the presence of an isotype-matched antibody control (MOPC 21) showed no change in the anti-OVA humoral response. The predominant anti-OVA response that was enhanced by UC1MT treatment was the IgG(1) response; the IgG(2a) anti-OVA response was not altered by UC1MT treatment. UC1MT treatment increased the numbers of IgG anti-OVA secreting cells as measured by ELISPOT assay, suggesting that blocking the effects of MT synthesized during the immune response augments the differentiation of antigen-specific plasma cells. The percentages of T and B cells in the spleens of animals from each treatment group were not significantly different, suggesting that this regimen of UC1MT treatment does not significantly affect hematopoiesis, but rather alters antigen-induced differentiation of lymphocytes. These observations are compatible with previous results from our laboratory that suggest that endogenous MT synthesized during the normal immune response or as a consequence of toxicant exposure suppresses in vivo immune function. In light of the fact that significant amounts of MT can be synthesized during toxicant exposure, manipulation of MT levels with an anti-MT antibody may ultimately represent an important therapeutic approach to the treatment of immune dysfunctions that result from toxicant exposure.

Effect of late modulation of nitric oxide production on murine lupus

MRL/MpJ-Faslpr (MRL-lpr) and New Zealand Black/ White (NZB/W) mice develop spontaneous autoimmune disease characterized by autoantibody production and glomerulonephritis that progresses in parallel with increasing systemic nitric oxide (NO) production. A previously published study from our laboratory indicated that oral administration of the nitric oxide synthase inhibitor NG-monomethyl-L-arginine (NMMA) before the onset of clinical disease significantly decreased renal and joint pathology in MRL-lpr mice. To characterize the effect of late modulation of NO production in murine SLE, we administered oral NMMA and/or restricted dietary arginine after disease onset in two murine models of SLE. When receiving combined NMMA and arginine restriction, MRL-lpr mice had reduced joint pathology scores and NZB/W mice had lower renal pathology scores than control mice. These results indicate that modulating NO production after the onset of disease diminishes disease severity in two models of SLE, although not as effectively as treating before disease onset.

Priming of NADPH oxidase by tumor necrosis factor alpha in patients with inflammatory and autoimmune rheumatic diseases

Oxidative damage caused by oxygen free radicals from activated phagocytes contributes to the pathology of arthritis. The present study evaluates the activity of NADPH oxidase of neutrophils and monocytes from patients suffering from various inflammatory and autoimmune rheumatic disease. Production rates of reactive oxygen species [ROS] of neutrophils and monocytes from rheumatic patients are compared to those of healthy controls and non rheumatic disease controls and correlated with the plasma levels of tumor necrosis factor alpha, C-reactive protein and the sedimentation rates of erythrocytes. There was a two- to eightfold increase in phagocytic superoxide production in rheumatic patients, when compared to healthy subjects or patients with non-rheumatic internal diseases [p < 0.005]. The enhanced NADPH oxidase-dependent superoxide generation correlated well with elevated levels of tumor necrosis factor alpha [TNF-alpha] in plasma [p = 0.005], suggesting a causal relation. There was no correlation with the plasma levels of C-reactive protein and a weak though significant correlation with the sedimentation rates of erythrocytes [p = 0.043]. Removal of circulating TNF-alpha by dialysis of patients blood and inhibition of NADPH oxidase by prednisolone treatment normalized elevated ROS production to the levels of healthy controls and correlated with the clinical improvements. Our data support the hypothesis of a central role for TNF-alpha during the development of arthritis. The chemiluminescence assay described here may be useful as a convenient screen and as a potential follow up procedure for individual patients with rheumatic diseases.

Hepatoprotective reactivity of a copper-di-Schiffbase active centre analogue of Cu2Zn2 superoxide dismutase

1. The anti-inflammatory and hepatoprotective efficacy of CuPu(Py)2 ((N,N'-bis(2-pyridyl-methylene)-1,4-butanediamine) (N,N',N",N")-Cu2+), a serum-stable, copper-di-Schiffbase active centre analogue of Cu2Zn2 superoxide dismutase was tested in male NMNR mice suffering from endotoxin/galactosamine-induced hepatitis. 2. Parameters including the activities of serum transaminases and sorbitol-dehydrogenase as well as the levels of reactive oxygen and nitrogen intermediates which were used to quantify the disease activity. 3. A dose-dependent inhibition of hepatic enzyme release was noted in the presence of 0.1-10 mg/kg of CuPu(Py)2. 4. The release of transaminases from damaged liver cells was reduced by 68% and paralleled the reduction of serum levels of nitric oxides. 5. Elevated levels of reactive oxygen species were normalized to those healthy controls. 6. The copper-free apochelate Pu(Py)2, which is unable to dismutate superoxide, did not display any anti-inflammatory reactivity.

Modulation of inflammatory arthritis by inhibition of poly(ADP ribose) polymerase

Poly(ADPR) polymerase (PARP; EC 2.4.2.30) is a nuclear enzyme, which, when activated by oxygen- and nitrogen-radical-induced DNA strand breaks, transfers ADP ribose units to nuclear proteins and initiates apoptosis by depletion of cellular NAD and ATP pools. The present study investigates whether the oxidative stress-dependent activation of PARP plays a role in the etiopathogenesis of arthritis. The antiarthritic reactivity of the biogenic PARP inhibitor nicotinamide was tested in DBA/1 x B10A(4R) mice suffering from potassium peroxochromate-induced arthritis. Daily doses of 4 mmol/kg of NA suppressed the arthritis by 35% and inhibited the phagocytic generation of reactive oxygen species, which increases sixfold during the development of arthritis. The onset, progression, and remission of arthritis correlated positively to the phorbolester-activated respiratory burst of neutrophils and monocytes, and a dose-dependent inhibition of NADPH oxidase activity was determined with human phagocytes. Our data support the hypothesis that oxidative stress-induced alterations in cellular signal transduction pathways play a pivotal role in the development of arthritis, which can be suppressed by the simultaneous inhibition of poly(ADPR) polymerase and NADPH oxidase.

Antiinflammatory effects of NADPH oxidase inhibitors

Proinflammatory cytokines prime the membrane-bound NADPH oxidase of neutrophils and monocytes of mice suffering from experimental arthritis so as to attain an activated state, which, upon a second stimulus, releases 6-fold increased levels of reactive oxygen species (ROS) than do unprimed phagocytes. Enhanced NADPH oxidase activity deregulates ROS-dependent signal transduction pathways of inflammation, which play a crucial role in the pathogenesis of arthritis. The antiarthritic reactivity of two inhibitors of NADPH oxidase, diphenylene iodoniumchloride (DPI) and staurosporine, was tested in male DBA/1 x B10A(4R) hybrid mice suffering from potassium peroxochromate arthritis. Daily doses of 2.8 mumol/kg of DPI or 30 nmol/kg of staurosporine sufficed to inhibit the arthritis by 50%. A complete inhibition was obtained with 10 mumol/kg of DPI, and 100 nmol/kg of staurosporine suppressed the arthritis by 85%. The onset, progression, and remission of arthritis correlated to both the activity of phagocytic NADPH oxidase (r = 0.750) and to overt disease symptoms as judged by the arthritis index. Our data support the hypothesis that oxidative stress plays a pivotal role in the pathology of arthritis, which can be therapeutically targeted by NADPH oxidase inhibitors.

Suppression of arthritis by an active center analogue of Cu2Zn2-superoxide dismutase

The anti-arthritic and anti-inflammatory efficacy of CuPu(Py)2 ([N,N'-bis(2-pyridylmethylene)-1,4-butanediamine] (N,N',N",N"))-Cu(II), a serum-stable active center analogue of Cu2Zn2-superoxide dismutase (SOD; EC 1.15.1.1), was tested in male DBA/1 x B10A (4R) mice suffering from potassium-peroxochromate-induced (PIA) or collagen type II-induced arthritis (CIA). Parameters including the arthritis index, the plasma SOD activity, and the inhibition of phagocytic responses in unseparated blood were used for the assessment of disease activity. A dose-dependent suppression of arthritis was noted in both models. The ED50 was 2.5 +/- 0.4 mumol/kg/day of CuPu(Py)2 for PIA and 4.0 +/- 1.1 mumol/kg/day for CIA. The arthritis index correlated with both the levels of reactive oxygen species (ROS) generated by phorbol ester-activated neutrophils and monocytes in unseparated blood (r = 0.892) and the SOD-like activity in plasma (r = 0.857). CuPu(Py)2 inhibited also the lipoplysaccharide-induced release of tumor necrosis factor alpha from human monocytes and neutrophils in a dose-dependent manner. Unlike SOD, which exerts successful anti-rheumatic activity mainly upon intra-articular injection, the SOD-mimic CuPu(Py)2 can be applied systemically. Non-proteinaceous low molecular weight antioxidases may well be suited to control oxidative stress-derived damage in rheumatic diseases by modulation of ROS-dependent signal transduction pathways.

Reactivity of an active center analog of Cu2Zn2superoxide dismutase in murine model of acute and chronic inflammation

The antiinflammatory efficacy of CuPu(Py)2 ([[N,N'-bis(2-pyridylmethylene)-1,4-butanediamine] (N,N',N'',N''')]-Cu2+), a serum stable active center analog of Cu2Zn2superoxide dismutase (SOD), was tested in vitro and in vivo in male Wistar rats suffering from potassium peroxochromate-induced inflammation. Parameters including 99mTc gamma-scintigraphic imaging, the arthritis score, the plasma superoxide dismutase activity, the inhibition of plasma sulfhydryl depletion as well as mitogenic and phagocytic responses were used to quantify the disease activity. All parameters improved impressively during the treatment with CuPu(Py)2 and resembled those of healthy animals after 21 days. The arthritis score was inhibited by 80% (P > 0.001) and the plasma SOD activity enhanced by 380% (P > 0.001). The depletion of plasma sulfhydryls and the leukocytic responses to concanavalin A, tetradecanoylphorbolacetate, and lipopolysaccharide were significantly reduced (P > 0.001) and correlated well with the arthritis score. The collapse of antioxidant defenses in human plasma as well as the depolymerization of hyaluronic acid was mimicked in vitro and successfully inhibited by CuPu(Py)2. Oxidant-induced injury of plasma components during the aqueous decay of potassium peroxochromate were demonstrated to activate the oxidative burst of phagocytes in human blood. The role of impaired pro- and antioxidant balances in the etiology of inflammatory and autoimmune rheumatic diseases is discussed.

Elevated levels of xanthine oxidase in serum of patients with inflammatory and autoimmune rheumatic diseases

Sera of patients with various inflammatory and autoimmune rheumatic diseases were screened for the presence of xanthine oxidase (XOD) and compared to sera from healthy donors and patients with nonrheumatic diseases including AIDS, internal diseases, and different carcinomas. Up to 50-fold higher levels of XOD were detected in rheumatic sera (P < 0.001). In addition, serum sulfhydryls (SH) were determined as sensitive markers of oxidative stress. The SH status in rheumatic patients was diminished by 45-75% (P < 0.001) and inversely correlated to the concentration of serum XOD (R = 0.73), suggesting a causal interrelation. The depletion of serum sulfhydryls by the oxyradical-producing XOD/acetaldehyde system was mimicked successfully ex vivo in human serum from healthy donors. Cortisone treatment of patients suffering from systemic lupus erythematosus and rheumatoid arthritis impressively normalized elevated XOD concentrations in rheumatic sera to those of healthy controls. The participation of xanthine oxidase in the depletion of serum antioxidants in rheumatic patients is discussed in the light of substrate availability and Km values.