Effect of stimulated neutrophils from the synovial fluid of patients with rheumatoid arthritis on lymphocytes--a possible role of increased oxygen radicals generated by the neutrophils

Hyaluronan and synovial joint: function, distribution and healing

Synovial fluid is a viscous solution found in the cavities of synovial joints. The principal role of synovial fluid is to reduce friction between the articular cartilages of synovial joints during movement. The presence of high molar mass hyaluronan (HA) in this fluid gives it the required viscosity for its function as lubricant solution. Inflammation oxidation stress enhances normal degradation of hyaluronan causing several diseases related to joints. This review describes hyaluronan properties and distribution, applications and its function in synovial joints, with short review for using thiol compounds as antioxidants preventing HA degradations under inflammation conditions.

Potential antioxidant mechanism of action for metronidazole: implications for rosacea management

Chronic inflammation is believed to account for some symptoms of rosacea. The efficacy of topical metronidazole in the treatment of rosacea may be due to its antimicrobial as well as anti-inflammatory activity. Neutrophils release potent inflammatory mediators, including reactive oxygen species (ROS), and intrafollicular neutrophils have been observed in stage II disease. ROS and other free radicals may contribute to intrinsic and extrinsic aging, both of which accentuate clinical manifestations of rosacea. If, as in vitro data suggest, metronidazole has antioxidant activity, it may help subdue the oxidative tissue damage of intrinsic and extrinsic aging as well as prevent and treat rosacea symptoms.

Inhibitory effect of local anaesthetics on reactive oxygen species production by human neutrophils

BACKGROUND

Reactive oxygen species (ROS) generated from neutrophils accumulated in various major organs are thought to play a pivotal role in the pathogenesis of host auto-injury. Lidocaine has been shown to reduce the injury. We investigated the effect of local anaesthetics (lidocaine, mepivacaine and bupivacaine) on ROS production by neutrophils using an in vitro system.

METHODS

We measured the production of superoxide (ferricytochrome c method), hydrogen peroxide (H2O2: scopoletin fluorescence technique), and hydroxyl radical (OH.: ethylene gas method) by neutrophils isolated from human adult volunteers in the absence and presence of lidocaine (2-200 micrograms/mL), mepivacaine (3-300 micrograms/mL), and bupivacaine (3-300 micrograms/mL). We also measured the ROS generation in a cell-free (xanthine-xanthine oxidase) system.

RESULTS

Lidocaine and mepivacaine at higher levels significantly decreased the production of ROS by neutrophils. However, these local anaesthetics at clinically relevant blood concentrations had no effect on the levels of ROS. Furthermore, lidocaine and mepivacaine failed to reduce ROS generated by the cell-free system. Bupivacaine did not decrease ROS generation by either generating system.

CONCLUSION

In conclusion, in the present in vitro system, only concentrations of lidocaine and mepivacaine 100-fold higher than clinically feasible ones reduced ROS production by human neutrophils. However, the local anaesthetics at clinically relevant blood concentrations had no suppressive effect. Further studies using in vivo systems are required to elucidate the inhibitory effects of local anaesthetics on ROS generation in clinical settings.

Polymorphonuclear neutrophils enhance suppressive activities of anti-CD3-induced CD4+ suppressor T cells

We investigated the effects of polymorphonuclear neutrophils (PMN) on the suppressive activities of CD4+ suppressor T cells induced by immobilized mAb to the CD3 molecular complex in order to explore the role of PMN in the regulation of humoral immune responses. CD4+ T cells that had been treated with mitomycin C induced the IgM production from highly purified B cells in cultures stimulated with immobilized anti-CD3. Addition of CD4+ T cells that had not been treated with mitomycin C (control T4 cells) suppressed the IgM production induced by immobilized anti-CD3-stimulated T4 mito. PMN enhanced the degree of suppression of the IgM production by anti-CD3-stimulated control T4 cells. The capacity of PMN to enhance the suppressive activity of anti-CD3-stimulated control T4 cells was restored when PMN were fixed with paraformaldehyde (PFA), suggesting that direct interactions between PMN and CD4+ T cells, but not soluble factors secreted by PMN, were involved in the enhancement of suppression. Fresh PMN as well as PFA-fixed PMN enhanced the endogenous IL-2 production by immobilized anti-CD3-stimulated CD4+ T cells. Moreover, neither fresh PMN nor PFA-fixed PMN significantly augmented the suppressive activity of anti-CD3-stimulated control T4 cells in the presence of exogenous IL-2. These results indicate that PMN enhance the suppressive activity of anti-CD3-stimulated control T4 cells through direct interactions between PMN and CD4+ T cells. The enhancement of the suppressive activity of CD4+ suppressor T cells by PMN is accounted for by the enhancement of the endogenous IL-2 production by anti-CD3-stimulated CD4+ T cells. Thus, the data demonstrate that PMN influence the magnitude of humoral immune responses by regulating the production of IL-2 through direct interactions with T cells.

Oxygen free radicals and human disease

Oxygen free radicals are very reactive molecules which can react with every cellular component. They are normally produced in organisms being involved in various biologic reactions. However, too high levels of these partially-reduced O2 species can give rise to functional and morphologic disturbances in cells. There is evidence to implicate oxygen free radicals as important pathologic mediators in many human disease processes.

The influence of age and sex on phagocyte chemiluminescence

The process of ageing is associated with increased susceptibility to infection. Phagocytes form the primary defence mechanism against infecting microorganisms, but the influence of ageing on phagocyte function remains controversial. In this study we have applied a microtitre plate phagocyte chemiluminescence (CL) assay suitable for clinical use to compare phagocyte oxidative metabolism in younger healthy subjects (age 20-60 years) and healthy older (60-70 years) subjects. Polymorphonuclear leukocytes (PMNL) and monocytes were stimulated using phorbol myristate acetate (PMA), serum opsonized zymosan (SOZ), and non-opsonized zymosan (ZYM) in the presence of both lucigenin and luminol. Monocytes showed a higher luminol-enhanced CL response to PMA in males compared with females in the younger age group. No PMNL differences were observed between the sexes. Although no differences were found in relation to age when cells were stimulated with PMA and SOZ, significantly lower background (unstimulated) CL was obtained from PMNL with luminol. PMNL luminol-enhanced CL responses were also lower in response to ZYM. The findings suggest a reduced response of PMNL from older subjects to minimal stimulation. This could be related to abnormalities in the triggering of the respiratory burst or myeloperoxidase release due to ageing. The influence of age and sex should be taken into account in clinical studies of phagocyte CL.

Inhibitory effect of prostaglandin E1 on human neutrophil function

Neutrophils accumulated in the lung are thought to play a pivotal role in the pathogenesis of host auto-injury such as adult respiratory distress syndrome (ARDS). We investigated the effect of prostaglandin E1 (PGE1) on several aspects of human neutrophil function. PGE1 significantly decreased reactive oxygen species (ROS), (O2-, H2O2, OH.) generation by neutrophils as well as neutrophil phagocytosis and chemotaxis. In contrast, the drug did not affect the levels of ROS generated by a cell-free ROS generating system. In addition, intracellular calcium concentrations ([Ca2+]i) in neutrophils stimulated by f-Met-Leu-Phe were decreased in the presence of PGE1. These data suggest that the reduction in ROS production and neutrophil phagocytosis and chemotaxis by PGE1 may contribute to the effectiveness of the drug in host auto-injury including ARDS. The suppression of the increase in [Ca2+]i may at least be responsible for inhibition of these neutrophil functions by PGE1.

Inhibitory effect of gabexate mesilate on human neutrophil function

Neutrophils accumulated in the lung are thought to play a key role in the pathogenesis of adult respiratory distress syndrome and interstitial pneumonia following bone-marrow transplantation. The effects of gabexate mesilate on several aspects of human neutrophil function have been investigated. Gabexate mesilate significantly decreased both the generation of reactive oxygen species (O2-, H2O2, OH.) by neutrophils and neutrophil chemotaxis. In contrast, the drug did not affect the levels of reactive oxygen species generated by a cell-free reactive-oxygen-species generating system. Intracellular calcium concentrations in neutrophils stimulated by f-Met-Leu-Phe were decreased in the presence of gabexate mesilate. These data suggest that the reduction in reactive-oxygen-species production and neutrophil chemotaxis by gabexate mesilate may contribute to the effectiveness of the drug in adult respiratory distress syndrome and interstitial pneumonia after bone-marrow transplantation. The suppression of the increase in intracellular calcium concentration may at least be responsible for the inhibition of these neutrophil functions by gabexate mesilate.

Changes in lipid peroxide levels and activity of reactive oxygen scavenging enzymes in skin, serum and liver following UVB irradiation in mice

The effect of acute UVB on the generation of reactive oxygen species (ROS) in the skin and the induction of ROS scavenging enzymes in situ was examined. Lipid peroxide levels and the activities of superoxide dismutase (SOD), catalase, glutathione peroxidase (GSH-Px) and D-glucose-6-phosphate dehydrogenase (G-6-P-D) were determined in the skin, serum, and liver of ICR mice subjected to 1400 mJ/cm2 of acute UVB irradiation. In irradiated skin, lipid peroxides were increased at 3 and 24 hr after irradiation, whereas the four ROS scavenging enzymes were generally decreased during the first 48 hr after irradiation. In the serum, lipid peroxides showed an increase at 3 hr, but enzyme activities remained negligible. In the liver, lipid peroxides showed similar behaviour to that in skin. GSH-Px activity in the liver was decreased during the first 24 hr, whereas G-6-P-D showed substantial fluctuation and SOD and catalase activities showed no change. These data are consistent with a model in which lipid peroxides generated in the UVB-irradiated lesions are transported to the liver and there metabolized by the scavenging enzymes induced in situ.

Effects of cepharanthin on neutrophil chemotaxis, phagocytosis, and reactive oxygen species generation

The effects of cepharanthin on inflammatory parameters such as neutrophil chemotaxis, phagocytosis and reactive oxygen species (ROS) generation, were examined. Cepharanthin significantly decreased the levels of O2-, H2O2, and OH. generated by neutrophils. H2O2 and OH. generated in a cell-free, xanthine-xanthine oxidase system were also reduced in the presence of cepharanthin. However, the drug did not affect neutrophil chemotaxis or phagocytosis. The present study indicates that cepharanthin is an effective ROS scavenger, exerting its anti-inflammatory action by reducing the potent ROS species excessively generated in tissues and organs, especially at the sites of inflammation.

Kojic acid scavenges free radicals while potentiating leukocyte functions including free radical generation

The effects of kojic acid, a compound that suppresses melanogenesis and is widely consumed in the Japanese diet with the belief that it is beneficial to health, were investigated on several aspects of leukocyte function. Kojic acid significantly decreased the levels of reactive oxygen species (ROS) (O2-, H2O2, OH.) generated by neutrophil and by a cell-free ROS-generating system. In contrast, it significantly enhanced neutrophil phagocytosis and ROS generation, and lymphocyte proliferation stimulated by phytohemagglutinin. In addition, calcium concentration, [Ca2+]i in human neutrophils was increased in the presence of kojic acid. These results suggest that kojic acid is a favorable agent in terms of host defense in that it enhances a number of activities of leukocytes, but scavenges ROS excessively released from cells or generated in the tissues or blood vessels that are potentially injurious to host tissues.

Inhibitory effect of azelaic acid on neutrophil functions: a possible cause for its efficacy in treating pathogenetically unrelated diseases

It has been shown that acne, hyperpigmentation and lentigo malignant are more or less related pathogenetically to reactive oxygen species (ROS). It has recently been reported that azelaic acid is effective in treating these conditions and that it possesses anti-enzymatic and antimitochondrial activity, including cytochrome-P450 reductase and 5 alpha-reductase in microsomal preparations with nicotinamide adenine dinucleotide phosphate (NADPH). We therefore investigated the effects of azelaic acid on human neutrophil functions, such as chemotaxis, phagocytosis and ROS generation. ROS generation in a cell-free system was also assessed. The results revealed that neutrophil chemotaxis and phagocytosis as well as ROS generated in a xanthine-xanthine-oxidase system were not significantly changed in the presence of azelaic acid. However, azelaic acid markedly decreased O2- and OH. generated by neutrophils. It may be concluded that the reported clinical effectiveness of azelaic acid is partly due to its inhibitory action on neutrophil-generated ROS, leading to a reduction both in oxidative tissue injury at sites of inflammation and in melanin formation.

Oxygen radicals, inflammation, and arthritis: pathophysiological considerations and implications for treatment

A vast amount of circumstantial evidence implicates oxygen-derived free radicals, especially superoxide and hydroxyl radical (and to lesser extent, hydrogen peroxide), as mediators of inflammation and/or tissue destruction in inflammatory and arthritic disorders. The substrates for radical generation, namely properly stimulated phagocytic cells, transition metal catalysts, and (to a limited extent) ischemia, are all amply present, although there is no particular rheumatic disease in which a consistent abnormality of radical generation has been identified. These radical species can clearly degrade hyaluronic acid, modify collagen and perhaps proteoglycan structure and/or synthesis, alter and interact with immunoglobulins, activate enzymes and inactivate their inhibitors, and possibly participate in chemotaxis. In most situations, however, there is ample scavenging ability to detoxify these radicals before they hit their target, and many rheumatic disease drugs can decrease their production and/or effects. Despite the apparent sufficiency of natural scavengers and the lack of direct evidence that oxygen radicals are pathogenetically important, substantial pharmaceutical effort is still being made to develop free radical scavengers as therapeutic agents. Although individual free radicals die out quickly, rheumatologic interest in them has been sustained for nearly two decades.

Free radical scavenging action of Bio-catalyzer alpha.rho No.11 (Bio-normalyzer) and its by-product

Bio-catalyzer alpha.rho No.11 (Bio-normalyzer) and its by-product are natural health products made by yeast fermentation of glucose, Carica papaya Linn., Pennisetum pupureum Schum., and Sechium edule Swartz. Their effects on free radicals were examined by electron spin resonance spectrometry using spin trapping agent 5,5-dimethyl-1-pyrroline-1-oxide (DMPO). It was observed that both Bio-catalyzer and its by-product scavenged 95% of DMPO-OH spin adducts (89 x 10(15) spins/ml) generated by FeSO4-H2O2-diethylene triamine pentaacetic acid system at 45.45 mg/ml each. Five percent of DMPO-O2- spin adducts (27 x 10(15) spins/ml) generated by hypoxanthine-xanthine oxidase system and 11% of 1,1-diphenyl-2-picrylhydrazyl radicals (7 x 10(15) spins/ml) were quenched using 25 mg/ml of Bio-catalyzer while 5% of superoxide and nil DPPH radicals were scavenged by its by-product. Vivo tests showed that oral administration of 1-g/kg body weight of Bio-catalyzer significantly inhibited thiobarbituric acid reactive substances formation, which is an index of lipid peroxidation, in the FeCl3-induced epileptic focus of rats. These findings suggest that Bio-catalyzer or its by-product may be useful health foods against neural lipid peroxidation, traumatic epilepsy and aging.

The inhibition of free radical generation by human neutrophils through the synergistic effects of metronidazole with palmitoleic acid: a possible mechanism of action of metronidazole in rosacea and acne

Metronidazole is clinically effective in treating not only rosacea but also acne inflammation. Yet it is generally considered not to be very effective in inhibiting the growth of anaerobic Propionibacterium acnes. We report here our investigation into the synergistic effects of metronidazole and palmitoleic acid on the anaerobic growth of P. acnes as well as on human neutrophil functions, including the generation of reactive oxygen species (ROS). Both metronidazole and palmitoleic acid, when used alone, only slightly inhibited the growth of P. acnes, and no significant decrease in human neutrophil functions, including the generation of ROS, was observed. But metronidazole used in the presence of palmitoleic acid markedly inhibited the anaerobic growth of P. acnes and decreased ROS generation by neutrophils. However, ROS generated in the xanthine-xanthine oxidase system were not affected. Metronidazole was shown to be clinically effective by decreasing neutrophil-generated ROS at the sites of inflammation with the aid of palmitoleic acid, which is generally present in human skin. By inhibiting oxidative tissue injury under in vivo conditions, treatment with metronidazole results in remarkable improvement of rosacea and acne.

Suppressive effects of linoleic acid on neutrophil oxygen metabolism and phagocytosis

On the basis of recent reports that the proportion of linoleic acid (C18:2Cis 9,12), a free fatty acid, is markedly decreased in acne comedones and that tetracycline is effective against acne comedones by acting directly as an antioxidant on infiltrating neutrophils, we investigated the effect of linoleic acid on several inflammatory parameters of neutrophils, including neutrophil chemotaxis, phagocytosis, and generation of reactive oxygen species (ROS). Linoleic acid significantly decreased phagocytosis and the generation of O2-, H2O2, and OH.by neutrophils, whereas it did not significantly inhibit neutrophil chemotaxis or decrease the ROS levels generated in a cell-free, xanthine-xanthine oxidase system. The present study seems to suggest that decreased levels of linoleic acid in acne comedones contribute, in part, to the worsening of acne inflammation by the failure of low levels of linoleic acid to suppress neutrophil phagocytosis and ROS generation.

Neutrophil-potentiating factors released from stimulated lymphocytes; special reference to the increase in neutrophil-potentiating factors from streptococcus-stimulated lymphocytes of patients with Behçet's disease

The potentiating effect of the soluble factors released from normal or diseased lymphocytes on neutrophil functions were investigated in the presence or absence of mitogens and wall preparations of Streptococcus pyogenes. When normal T lymphocyte populations were stimulated with T cell mitogens or with streptococcal preparations, the supernatants from these cultures potentiated neutrophil chemotaxis, phagocytosis and O2- generation. Upon gel-filtration of these stimulated lymphocyte supernatants, the neutrophil-potentiating activity was inactivated by trypsin or by a 30-min incubation at 130 degrees C, but was not affected by acid treatment at pH 2 or heat treatment at 56 degrees C for 60 min. Its activity was almost not affected by antisera against human interleukin-1, interleukin-2, interferon-gamma or tumour necrosis factor. With the stimulation of T cell mitogens, the supernatants released from the lymphocytes of not only the patients with Behçet's disease but also healthy and diseased controls enhanced neutrophil functions. However, supernatants from streptococcal preparation-stimulated lymphocytes from patients with Behçet's disease had a higher potentiating effect on neutrophil functions. Our study suggests that the enhanced neutrophil functions in patients with Behçet's disease may be related to an abnormally high level of circulating activated T cells in these patients.

Diminished superoxide production of synovial fluid neutrophils in patients with rheumatoid arthritis following piroxicam treatment

Superoxide production by polymorphonuclear leukocytes (PMNs) and macrophages was inhibited by piroxicam and other non-steroidal anti-inflammatory drugs both in vitro and in vivo. Hitherto, data have only been available on blood PMNs and macrophages. In order to investigate the situation in the joint, PMNs were isolated from synovial fluid before and after 24 h of piroxicam treatment in patients with rheumatoid arthritis. Isolated PMNs were stimulated with PMA and serum-treated zymosan. The capacity of synovial fluid PMNs to produce superoxide decreased by 30% after piroxicam treatment. A similar decrease was found for blood PMNs. No difference in superoxide production was found between blood PMNs and synovial fluid PMNs which were obtained simultaneously. From the fact that the piroxicam concentration in synovial fluid was 40% of the serum value, it can be concluded that piroxicam probably became bound to PMNs before they entered the joint cavity. These results indicate that at the site of the inflammation the superoxide production by PMNs is inhibited by piroxicam treatment. The inhibition of superoxide production is probably important in the effect of piroxicam and other non-steroidal anti-inflammatory drugs in rheumatoid arthritis.

Neutrophil chemotaxis, phagocytosis and parameters of reactive oxygen species in human aging: cross-sectional and longitudinal studies

To assess the effect of aging on neutrophil (PMN) functions and the parameters related to reactive oxygen species (ROS), we measured the following in blood samples from 166 asymptomatic aged individuals: PMN activities including chemotaxis, phagocytosis and generation of ROS; the activity of superoxide dismutase (SOD) of blood cell; and serum lipid peroxide levels. Compared with non-aged adults, the older individuals showed markedly attenuated PMN chemotaxis, and slightly elevated serum lipid peroxide levels. Other parameters were not significantly different between the two aged groups. In contrast both to the elderly group as a whole and to the subgroup 65 to 79 years old, the subjects over greater than or equal to 80 years old showed normal PMN chemotaxis and serum lipid peroxide levels, as defined by the young adult control group. Thirty-two subjects who entered the study at ages 69 to 72 years were followed with serial assays for seven years; twenty-one of these subjects died during this observation period. There was a striking and significant difference between the survivors and nonsurvivors with regard to PMN chemotaxis and serum lipid peroxide levels; even when asymptomatic upon initial examination, the nonsurvivors showed diminished PMN chemotaxis and elevated lipid peroxide levels. It seems from both the cross-sectional and longitudinal parts of our study that PMN chemotaxis and serum lipid peroxide levels correlate with survival to advanced age.

Free radicals in medicine. II. Involvement in human disease

This review explores evidence that free radicals might be involved in various human disease processes. Such involvement is difficult to prove because direct evidence is often lacking and is based on animal models of the disease process. Evidence for free radical involvement includes demonstrating abnormal free radical production in the disease, finding that deliberately applying free radical-producing systems into the cellular locus responsible for the disease reproduces its manifestations, and showing that free radical scavengers control facets of the disease process. Confirmation of free radical involvement in a particular disease may have clinical relevance, inasmuch as clinically applicable techniques are currently being developed to remove free radicals from cellular sites where they are injurious and, in other situations such as chemotherapy, techniques or drugs that produce free radicals are available to destroy harmful cells.

Some characteristics of neutrophils from diabetic patients and their relation to the levels of circulating immune complexes

In the present work we studied different characteristics of neutrophils from diabetic patients and their relation to the levels of circulating immune complexes (CIC). Twenty-five insulin-dependent (IDD) and 25 non-insulin-dependent diabetic (NIDD) patients were evaluated. Each group was then subdivided according to the presence or absence of microvascular complications (MC). We found that the chemiluminescence (CL) emitted by opsonized zymosan (Zop) stimulated neutrophils in IDD and NIDD patients was significantly increased when compared to healthy subjects (p less than 0.01 and p less than 0.02, respectively). The CL values were correlated to CIC levels and both parameters were related to the presence of MC. On the other hand, the percentage of neutrophils capable of reducing nitroblue tetrazolium was diminished in the two groups of diabetic patients (p less than 0.05 for IDD and p less than 0.01 for NIDD). The percentage of neutrophils with functional C3b receptors was normal in diabetic patients; however, the proportion of phagocytic cells through Fc receptors was significantly decreased in both types of patients (p less than 0.05 and p less than 0.01 for IDD and NIDD, respectively). Furthermore, the number of granulocytes with immune complexes (IC) bound to their cell surface was increased in diabetics. We suggest that the increase of CIC level may produce an increase in IC binding to the neutrophil membrane. These IC could block the Fc receptors, diminish phagocytic capacity and, simultaneously, stimulate the release of toxic oxygen products, thus contributing to produce tissue damage.

Follow-up study of lipid peroxides, superoxide dismutase and glutathione peroxidase in the synovial membrane, serum and liver of young and old mice with collagen-induced arthritis

Because reactive oxygen species (ROS) are generally believed to play an important role in tissue injury in rheumatoid arthritis, we examined the levels of lipid peroxides, superoxide dismutase (SOD), and glutathione peroxidase (GSH-Px) in the synovial membrane, serum and liver of young (8 wk) and old (12 mo) mice with collagen-induced arthritis. In the synovial membrane, serum and liver, lipid peroxide levels of both young and old mice were increased beginning on the 3rd day after the onset of arthritis. SOD activity, which scavenges O2- and inhibits lipid peroxidation, rose markedly in the synovial membrane of young mice in parallel with the increase in lipid peroxide levels, but not so markedly in old mice. Liver GSH-Px activity, which metabolizes already formed lipid peroxides, also rose in young arthritic mice to a greater degree than in old mice. This study suggests that in inflammatory synovial lesions, lipid peroxides are generated due to an increase in ROS concentration, with resultant cytotoxicity, and that younger animals or humans can prevent this unfavorable reaction more effectively than aged ones by enzyme induction. The hypothesis that lipid peroxides formed in the oxidative lesions of the primary organ are released into the serum, trapped by the liver and metabolized there is further supported by the present study.

Antioxidant activity of synovial fluid, hyaluronic acid, and two subcomponents of hyaluronic acid. Synovial fluid scavenging effect is enhanced in rheumatoid arthritis patients

To test the scavenging of reactive oxygen species (ROS), we added synovial fluids from patients with rheumatoid arthritis (RA) and osteoarthritis, as well as hyaluronic acid (HA) and its 2 subcomponents, D-glucuronic acid and N-acetyl-D-glucosamine, to 2 ROS-generating systems, activated neutrophils and xanthine-xanthine oxidase. Synovial fluid from RA patients, HA, and D-glucuronic acid markedly decreased the O2-, H2O2, OH., and chemiluminescence measured in both systems. HA and synovial fluid, which are known to be susceptible to degradation by excessive ROS in RA patients, also seem to play an active role in protecting articular tissues from oxidative damage.

Superoxide dependent iron release from ferritin in inflammatory diseases

Convincing evidence is presented that oxygen free radicals are involved in the pathogenesis of rheumatoid arthritis (RA). Superoxide is produced by polymorphonuclear leucocytes (PMN) in synovial fluid and by macrophages in the synovial membrane. Tissue damage typical for free radical attack is detected in RA. No absolute deficiency of protective factors is found in RA compared to controls, but the available protection is insufficient to cope with all radicals formed. The toxicity of superoxide is increased by iron. It is doubtful whether a low molecular weight iron pool is present. Superoxide is able to release iron from ferritin, providing a suitable source of iron, for the formation of hydroxyl radicals. This new pathogenetic mechanism stimulates to the application of iron chelators in the treatment of RA. Preliminary results with desferrioxamine were disappointing because of serious side-effects. Hopefully in the future intra-articular injection of iron chelators with better pharmacodynamics will be possible. The interaction of free radicals and ferritin is probably also involved in the pathogenesis of other inflammatory diseases such as systemic lupus erythematosus, hepatitis, and haemochromatosus.

Reactive oxygen species selectively deplete normal T lymphocytes via a hydroxyl radical dependent mechanism

Chronic inflammatory synovitis is characterized by both lymphocytic infiltrates and persistent polymorph exudates. Activated polymorphs release reactive oxygen species (ROS) during inflammation, but the contribution that these make to the lymphocyte abnormalities associated with RA has been little studied. We therefore investigated the cytotoxic effects of the reactive oxygen species on human peripheral blood mononuclear cells (PBMC). PBMC were exposed to RPMI 1640 medium previously irradiated for up to 60 min. Consistent dose-dependent killing was observed at 24 h. Antioxidant studies indicated that H2O2 was the effective species. Catalase, which specifically degrades H2O2, gave almost total protection against cell death, while superoxide dismutase (SOD), thiourea, and mannitol were largely ineffective. Addition of exogenous H2O2 caused an identical pattern of cell death to that observed with irradiated medium. PBMC cultures supplemented with desferrioxamine (a ferric iron chelator) also gave significant protection, suggesting that H2O2 mediated its effects via OH radicals. Analysis of lymphocyte subpopulations showed that ROS caused a selective depletion, depending on the level of H2O2 present. Low levels induced a specific loss of CD8+ cells, while higher concentrations caused significant loss of CD4+ T cells as well. sIg+ B cells were unaffected at either concentration. This selective lymphotoxic effect of ROS may be of considerable importance in the pathogenesis of autoimmune inflammatory disease.

The ratio of lipidperoxides to superoxide dismutase activity in the skin lesions of patients with severe skin diseases: an accurate prognostic indicator

We studied 35 patients with active inflammatory skin diseases, measuring the levels of lipidperoxides and of the oxygen radical scavenging enzyme superoxide dismutase (SOD) in biopsy specimens of skin lesions. Lipidperoxide levels were markedly elevated in all patients. In fifteen patients with disease that was severe and highly resistant to therapy, SOD activity was only slightly increased, in comparison with normal controls. In contrast, in the twenty patients with mild disease that responded well to therapy, SOD activity was markedly elevated. The ratio of lipidperoxide levels to SOD activity was thus an accurate prognostic indicator, being elevated only in the group not responding to treatment. These findings suggest that the severity of allergic inflammatory skin disease and/or the response to treatment may in part be governed by the degree to which the patient's SOD activity is up-regulated in response to the generation of tissue-damaging substances such as lipidperoxides. Interestingly, our studies revealed the SOD activities of both normal and inflamed skin to be unexpectedly high; our data suggest that SOD plays a critical role in protecting the skin from the effects of oxygen radicals and ultraviolet light.

Evaluation of neutrophil acetyltransferase activity in patients with inflammatory disorders

The acetyltransferase activity of neutrophils from patients with inflammatory disorders was assayed using the homogenate preparation of neutrophils. The enzyme activity was evaluated on both non-stimulated and stimulated neutrophils. The enzyme activity of neutrophils from 21 patients with rheumatoid arthritis and 10 patients with Behcet's disease was not significantly different from that of the control group. In contrast, it was significantly elevated in patients with bacterial infection, especially that of non-stimulated cells. The increase in the enzyme activity best correlated with the degree of fever. The elevated enzyme activity tended to normalize during convalescence.

Effects of dietary fish oil supplementation on polymorphonuclear leukocyte inflammatory potential

Polymorphonuclear leukocytes (PMNLs) are an important contributor to inflammation and are thus a part of the pathophysiology of many human diseases. We assessed the effect of fish oil on PMNL inflammatory potential by measuring chemiluminescence and superoxide production before and after six weeks of daily cod liver oil ingestion by healthy volunteers. Phagocytosing PMNLs demonstrated a 27% decrease in chemiluminescence (P less than 0.05) and a 64% decrease in superoxide production (P less than 0.01), following the cod liver oil supplementation. Analysis of PMNL and platelet fatty acids revealed the appearance of eicosapentaenoic acid and a significant decrease in arachidonic acid in both types of cells.

Oxygen radical production by neutrophils from patients with bacterial infection and rheumatoid arthritis. Measurement of hydrogen peroxide may most accurately represent enhancement of oxygen radical production during infection

The production of three kinds of oxygen radicals (superoxide, hydrogen peroxide, and hydroxyl radicals) by neutrophils from patients with bacterial infection or rheumatoid arthritis was measured. The stimulators used in this study were opsonized zymosan (1 mg/ml), phorbol myristate acetate (20 ng/ml), A23187 (1 microM), and platelet activating factor (1 microM). Oxygen radical production by neutrophils from patients with rheumatoid arthritis was not significantly different from that of the control group. Hydrogen peroxide production by the neutrophils from patients with bacterial infection was significantly enhanced by only opsonized zymosan, but the production of the other kinds of oxygen radicals was not. Cytochalasin B reduced the production of hydrogen peroxide induced by opsonized zymosan more markedly than that of any other kind of oxygen radical. The measurement of hydrogen peroxide is suggested to be the most accurate indicator of the enhancement of intracellular production of oxygen radicals by neutrophils during infection.

Antioxidant action of natural health products and Chinese herbs

The scavenging effects of reactive oxygen species (ROS) by two natural health products, antioxidant analogs (AOA), and green magma (GM), and 16 medical Chinese herbs were investigated in two in vitro ROS-generating systems, activated neutrophils and xanthine-xanthine oxidase. Native, unheated AOA and GM products significantly reduced ROS levels, while unheated Chinese herbs had a negligible effect on ROS levels. In contrast, heat-extracted Chinese herbs and AOA markedly, and GM mildly, suppressed the levels of ROS in both systems. The ROS scavenging activity of these native, unheated products was unaffected by dialysis, but that of heated products was markedly diminished by dialysis. Further, the incubation of these products with gastric juice obtained by a gastric tube from healthy volunteers revealed results comparable to those induced by heat treatment with or without dialysis. Although the antioxidant activity of these natural products appears to be partly due to enzymes such as superoxide dismutase (SOD), the predominant factor seems to be low-molecular-weight ROS scavengers that are liberated or activated by gastric juice digestion as observed after heat treatment.

Antioxidant action of antimalarials

The effects of antimalarials, chloroquine and quinacrine, on the generation of reactive oxygen species were examined both in polymorphonuclear leucocytes and in the xanthine-xanthine oxidase system. Antimalarials showed inhibitory effects on the production of reactive oxygen species probably by affecting cell functions, such as membrane phospholipid methylation. It is suggested that antimalarial agents can work as antioxidants at the site of inflammation protecting against auto-oxidative tissue damage with resultant anti-inflammatory effects.

Role of stimulated neutrophils from patients with systemic lupus erythematosus in tissue injury, with special reference to serum factors and increased active oxygen species generated by neutrophils

To examine the possible correlation between tissue injury and neutrophil-produced active oxygen (AO) species in patients with systemic lupus erythematosus (SLE), we studied the capacity of the serum from six patients with untreated, active SLE to generate AO and release lysosomal enzymes by normal neutrophils. Cultured endothelial cells from human umbilical cord vein were incubated with serum-stimulated neutrophils to assess AO-induced tissue injury. Serum from patients with bacterial infections and healthy individuals served as controls. AO production was highest in the neutrophils stimulated with SLE patient-derived serum, while lysosomal enzyme release was only slightly increased. SLE neutrophils with or without stimulation and SLE serum-stimulated normal neutrophils produced significantly high levels of cytotoxicity upon coincubation with 51Cr-labeled human endothelial cells. These excessive cytotoxicities were reversed by the presence of superoxide dismutase and catalase, indicating the specificity of the AO effect on endothelial cell damage. These findings suggest that tissue damage in SLE may be partially due to excessive production of AO and that both neutrophils themselves and a serum factor which activates neutrophils are involved in the mechanism for vascular injury.

Methyltransferase and phospholipase A2 activity in membranes of neutrophils and lymphocytes from patients with bacterial and viral infections

Phospholipid methylation and phospholipase A2 activation in the cell membrane are necessary for the induction of cell function in neutrophils and lymphocytes. We assessed the activity of membrane-associated methyltransferase and phospholipase A2 in neutrophils and lymphocytes from patients with acute and severe bacterial and viral infections. In bacterial patients, methyltransferase and phospholipase A2 activities of neutrophils were significantly enhanced, and [3H]methyl incorporation of lymphocytes was slightly increased. In viral infections, only phospholipase A2 activity of the lymphocytes was increased. These enhanced enzyme activities paralleled disease activity of the two disorders. The methylated products detected by two-dimensional thin-layer chromatogram were confined to methylated phospholipids, indicating that our assay system measures specifically the activity of methyltransferase which mediates the translocation of membrane phosphatidylethanolamine (PE) to phosphatidylcholine (PC) and lyso-PC(LPC). The two enzymatic activities of both neutrophils and lymphocytes in bacterial infections and phospholipase A2 of lymphocytes may, in part, have some correlation to the defense mechanism in these two disorders.

Decreased oxygen radical generation by neutrophils from patients with measles presumably owing to activation of suppressor T lymphocytes

The capacity for the generation of oxygen radicals by polymorphonuclear leukocytes (PMNs) was assessed in 29 patients with measles and in control groups. Patients with secondary bacterial infections showed a significantly decreased generation of oxygen radicals; this abnormality did not persist for more than 2 months after disease onset. Normal PMNs incubated with T lymphocytes from these measles patients generated significantly fewer oxygen radicals than those incubated with T cells from either control group. However, normal PMNs incubated with non-T lymphocytes from these measles patients produced normal oxygen radical levels. In addition, irradiation above 1,500 rads of T lymphocytes abrogated the suppressive effect of T cells on PMNs. On the other hand, these abnormal findings were not observed in patients with measles but without secondary bacterial infections. The secondary bacterial infections sometimes seen in measles patients may result from a decrease in oxygen radical generation, presumably induced by the suppressive activity of the T lymphocytes of the patients.

Effect of liposomal-encapsulated superoxide dismutase on active oxygen-related human disorders. A preliminary study

Liposomal-encapsulated superoxide dismutase was clinically applied to patient showing an increase in neutrophil active oxygen generation, and those with diseases such as severe rheumatoid arthritis (RA), Crohn's disease and progressive systemic sclerosis (PSS) in which presence of a plasmatic clastogenic factor has been demonstrated. Liposomal SOD injection (2.5 mg twice a week) resulted in marked remission in 12 out of 16 patients with active Behcet's disease. The drug was impressively effective on patients with intestinal Behcet. Remission rates in the other diseases was 7 out of 8 mucocutaneous lymphnode syndrome (MCLS, Kawasaki disease) 3 out of 5 dermatitis herpetiformis, IgA linear bullous dermatosis or severe cement dermatitis, 4 out of 9 active and severe RA, 3 out of 3 PSS, 4 out of 4 Crohn's disease, 3 out of 4 colitis ulcerosa, and 2 out of 2 unresponsive (hemolytic) anemia. To be emphasized was that three severe active RA patients and two terminal-stage PSS patients with dyspnea due to lung fibrosis showed dramatic improvement after administration of liposomal SOD. In addition, in 13 out of 15 malignant neo plastic patients including cancer, malignant lymphoma and leucemia who were receiving radiotherapy (total dose, more than 4000 rads) and chemotherapy including anthracycline analogs (total over 450 mg/m2) and bleomycin, the drug also prevented the appearance of myocardiac injury and fibrosis, sometimes seen as a consequence of chemotherapy. Liposomal SOD, which shows no toxicity, has various advantages compared to free SOD preparations, and is highly and broadly applicable to various clinical disorders.

Oxygen metabolism in phagocytes of leprotic patients: enhanced endogenous superoxide dismutase activity and hydroxyl radical generation by clofazimine

We examined the generation of active oxygens (O2-, H2O2, and OH X ) and the superoxide dismutase (SOD) activity of polymorphonuclear leukocytes (PMNs) and monocytes from 14 leprotic patients manifesting a bacillary index above 2.2. Patients with disease of more than 4 years in duration showed significantly enhanced SOD activity and a decrease in O2- and OH X production. The antileprotic agent, clofazimine, significantly increased the generation of OH X in a dose-dependent manner, with a subsequent decrease in H2O2, but had no effect on the SOD activity of the PMNs and monocytes. In medium containing FeSO4 or Fe2+-EDTA, the drug elevated OH X production markedly further. Phagocytic SOD in PMNs and monocytes of leprotic patients was both host and bacillus derived, because the presence of cyanide, to which human-derived cuprozinc SOD is susceptible, did not completely abrogate SOD activity. The difficulty in treating leprosy may be partly ascribable to decreased phagocytic OH X generation, which in leprosy patients is apparently due to the uptake of Hansen bacillus-derived SOD. Clofazimine may be effective in leprosy by chelating Fe2+, with the resultant potentiation of the catalyzing activity of Fe2+ in the Haber-Weiss reaction increasing OH X formation from H2O2.

Enhanced neutrophilic functions in mucocutaneous lymph node syndrome, with special reference to the possible role of increased oxygen intermediate generation in the pathogenesis of coronary thromboarteritis

To examine the possible correlation between mucocutaneous lymph node syndrome and thromboarteritis, we studied the capacity of polymorphonuclear leukocytes from 30 pediatric patients with mucocutaneous lymph node syndrome to generate oxygen intermediates and to release lysosomal enzymes. Cultured endothelial cells from human umbilical cord vein were also incubated with PMNs to assess oxygen intermediate-induced tissue injury. Within five days of MLNS onset, oxygen intermediate production, except for chemiluminescence generation, was markedly increased and the 51Cr release from labeled endothelial cells was significantly elevated. The lysosomal enzyme release was slightly, but significantly, higher. In the presence of superoxide dismutase and catalase, the 51Cr release was reduced to the control level, indicating the specificity of the effect of oxygen intermediate endothelial cell damage. At more than six to seven days after MLNS onset, the PMN functions were normal or decreased and the 51Cr release was reduced. In view of reports that coronary occlusion may appear one week after MLNS onset, we suggest that in the early stage of MLNS, a marked increase in oxygen intermediate generation induced by activated PMNs gives rise to coronary vascular injury, possibly leading to thromboarteritis and aneurysm formation.