The interrelation of glutathione reductase, catalase, glutathione peroxidase, superoxide dismutase, and glucose-6-phosphate in the pathogenesis of rheumatoid arthritis

Rheumatoid arthritis (RA) is the most common form of inflammatory arthritis, a systemic autoimmune disease characterized by chronic inflammation of the synovial joints, ultimately leading to joint destruction and permanent disability, affecting 1% of the world population. Oxidative stress in rheumatoid inflammation, due to the fact that antioxidant systems are impaired in RA and caused by fee radicals, might have an essential role in etiology of RA. This review includes the interrelation of antioxidants against free radicals in RA patients. There is much evidence that antioxidant team that covers glutathione reductase, catalase, glutathione peroxidase, superoxide dismutase, and glucose-6-phopshate destroy reactive oxygen species and other free radicals through enzymatic as well as nonenzymatic means. The change in relative levels of antioxidants vis-à-vis free radical formation and level could be used as indicators for effective and earlier diagnosis of RA.

Differential effects of the tryptophan metabolite 3-hydroxyanthranilic acid on the proliferation of human CD8+ T cells induced by TCR triggering or homeostatic cytokines

Production of indoleamine 2,3-dioxygenase (IDO) by tumor cells, leading to tryptophan depletion and production of immunosuppressive metabolites, may facilitate immune tolerance of cancer. IDO gene is also expressed in dendritic cells (DC) upon maturation induced by lipopolysaccarides or IFN. We investigated IDO gene expression in melanoma cell lines and clinical specimens as compared to mature DC (mDC). Furthermore, we explored effects of L-kynurenine (L-kyn) and 3-hydroxyanthranilic acid (3-HAA) on survival and antigen-dependent and independent proliferation of CD8(+) cells. We observed that IDO gene expression in cultured tumor cells and freshly excised samples is orders of magnitude lower than in mDC, providing highly efficient antigen presentation to CD8(+) T cells. Non toxic concentrations of L-kyn or 3-HAA did not significantly inhibit antigen-specific CTL responses. However, 3-HAA, but not L-kyn markedly inhibited antigen-independent proliferation of CD8(+) T cells induced by common receptor gamma-chain cytokines IL-2, -7 and -15. Our data suggest that CD8(+) T cell activation induced by antigenic stimulation, a function exquisitely fulfilled by mDC, is unaffected by tryptophan metabolites. Instead, in the absence of effective T cell receptor triggering, 3-HAA profoundly affects homeostatic proliferation of CD8(+) T cells.

Costly carotenoids: a trade-off between predation and infection risk?

Carotenoid reserves in copepods seem costly in terms of predation risk because they make individuals conspicuous. However, carotenoids also seem to play an important role in immune defence as free radical scavengers. To test whether predation risk influences carotenoid levels and whether changes in carotenoid levels are related to changes in immune defence, I examined individual changes in large carotenoid and other lipid droplets upon exposure to predation risk and subsequent exposure to parasites in the copepod Macrocyclops albidus. Copepods reduced carotenoid reserves upon exposure to predators, through which they potentially avoided the costs of being conspicuous under predation risk. Thus, the size of carotenoid reserves is a plastic trait. Such a decrease in carotenoid reserves may also have a negative impact on the copepods' immune system as individuals that decreased their reserves suffered higher parasite prevalence upon exposure to the cestode Schistocephalus solidus. These results suggest that carotenoid reserves may be individually optimized to trade-off each individual's unique costs (predation risk) and benefits (immune defence) of having these reserves.

Superoxide dismutases in the lung and human lung diseases

The lungs are directly exposed to higher oxygen concentrations than most other tissues. Increased oxidative stress is a significant part of the pathogenesis of obstructive lung diseases such as asthma and chronic obstructive pulmonary disease, parenchymal lung diseases (e.g., idiopathic pulmonary fibrosis and lung granulomatous diseases), and lung malignancies. Lung tissue is protected against these oxidants by a variety of antioxidant mechanisms among which the superoxide dismutases (SODs) are the only ones converting superoxide radicals to hydrogen peroxide. There are three SODs: cytosolic copper-zinc, mitochondrial manganese, and extracellular SODs. These enzymes have specific distributions and functions. Their importance in protecting lung tissue has been confirmed in transgenic and knockout animal studies. Relatively few studies have been conducted on these enzymes in the normal human lung or in human lung diseases. Most human studies suggest that there is induction of manganese SOD and, possibly, extracellular SOD during inflammatory, but not fibrotic, phases of parenchymal lung diseases and that both copper-zinc SOD and manganese SOD may be downregulated in asthmatic airways. Many previous antioxidant therapies have been disappointing, but newly characterized SOD mimetics are being shown to protect against oxidant-related lung disorders in animal models.

Cytotoxicity in glioma cells due to interleukin-12 and interleukin-18-stimulated macrophages mediated by interferon-gamma-regulated nitric oxide

OBJECT

Interleukin (IL)-12 and IL-18 synergistically mediate antitumor responses through the production of interferon-gamma (IFNgamma) by T and natural killer (NK) cells. Recently, it has been reported that macrophages stimulated with these cytokines also produce IFNgamma, which led the authors to investigate the antiglioma activity of macrophages stimulated by the combination of these cytokines in vitro.

METHODS

Dish-adherent peritoneal exudate cells, which had been elicited in thioglycollate broth as a source of macrophages, were used in the experiment. The murine glioma cell lines VM-glioma and 203G were labeled with [3H]thymidine for a cytotoxicity assay of macrophages. In response to the combined stimulation by IL-12 and IL-18, macrophages expressed potent cytotoxic activity against glioma cells in association with increasing production of IFNgamma and nitric oxide (NO). Inhibitors of NO abrogated the cytotoxic activity of the macrophages, which had been induced by IL-12 and IL-18, despite the increase in IFNgamma production. Neutralization of IFNgamma or use of macrophages obtained from IFNgamma gene-knockout mice markedly reduced not only cytotoxic activity, but also NO production. Depletion of T and NK cells from the macrophage population, which was achieved using antibody plus complement treatment, slightly reduced macrophage activities, suggesting that these are the main effector cells, although T and NK cells may partially participate in this cytotoxicity.

CONCLUSIONS

Macrophages stimulated with IL-12 and IL-18 produced IFNgamma and NO, which in turn mediated the antiglioma response. Therefore, macrophages as well as T and NK cells play an important role in antitumor responses stimulated by IL-12 and IL-18.

Antioxidant agents have a different expression pattern in muscle fibers of patients with mitochondrial diseases

Respiratory chain dysfunction leads to reactive oxygen species (ROS) generation with following oxidative stress and cellular damage. A histochemical and immunohistochemical study was performed on muscle biopsies from 17 patients with mitochondrial disease [chronic progressive external ophthalmoplegia (CPEO), mitochondrial encephalomyopathy with lactic acidosis and stroke-like episodes (MELAS), myoclonic epilepsy with ragged red fibers (MERRF)] to evaluate the expression pattern and location of manganese superoxide dismutase (MnSOD), copper-zinc superoxide dismutase (CuZnSOD) and reduced glutathione (GSH) in skeletal muscle fibers. Our data showed that: (1) MnSOD, CuZnSOD and GSH are expressed in fibers with respiratory chain deficiency; (2) the antioxidant induction is correlated with the degree of mitochondrial proliferation, but not with clinical phenotype, patients' age, duration of disease, biochemical defects or mitochondrial DNA abnormalities. In addition, we suggest that expression of MnSOD and GSH may be considered an initial, indirect sign of respiratory chain dysfunction because it is observed in the early stages of the disease.

Prime solutions for cardiopulmonary bypass in neonates: antioxidant capacity of prime based on albumin or fresh frozen plasma

OBJECTIVE

Oxidative damage and inflammation are believed to play an important role in postoperative complications after cardiopulmonary bypass. During bypass, a prime solution with a high antioxidant capacity may reduce the oxidative damage and inflammation. We investigated total antioxidant capacity and individual scavengers during the preparation of 2 different prime solutions.

METHODS

The prime solutions were prepared with either pasteurized human albumin or fresh frozen plasma. The total antioxidant capacity was measured with the total radical antioxidant parameter assay and with the ferric-reducing ability of plasma assay. The individual scavengers vitamin C, sulfhydryl groups, uric acid, and total protein were measured before, during, and after the prime preparation. Malondialdehyde was measured as a parameter for lipid peroxidation.

RESULTS

Neither prime solution showed a total radical antioxidant parameter value. The ferric-reducing ability of plasma value of prime solutions was lower than that of undiluted human albumin or fresh frozen plasma. Addition of mannitol did not increase the ferric-reducing ability of plasma value. Vitamin C was only found in the fresh frozen plasma prime. Both prime solutions contained sulfhydryl groups and uric acid in low concentrations. During ultrafiltration, low-molecular-weight antioxidants were lost into the ultrafiltrate.

CONCLUSIONS

We showed that prime solutions based on either albumin or fresh frozen plasma had very low antioxidant capacity and that ultrafiltration of the prime solution further lowers this capacity. A prime solution with a low antioxidant capacity may increase oxidative stress in neonates undergoing cardiopulmonary bypass.

Effects of a hydroxyl radical scavenger, EPC-K1, and neutrophil depletion on reperfusion injury in rat skeletal muscle

Oxygen free radicals (OFR) and neutrophils are potent sources of reperfusion injury. We compared the effect of EPC-K1, a new OFR scavenger, and neutrophil depletion on the reperfusion injury in skeletal muscle, using an ischemic revascularized hindlimb model in rats. Warm ischemia, produced by vascular pedicle clamping, was sustained for 4 h. After 24 h of reperfusion, muscle function and damage were evaluated in 4 groups: a sham operation group, a control study group, a group treated by EPC-K1 (EPC group), and a group that received nitrogen mustard to induce neutropenia (NM group). Both the EPC and NM groups had limited muscle damage compared to the control group. The EPC group preserved muscle function significantly better than the control group and the mean isometric tetanic tension in the EPC group appeared to be higher than that in the NM group. Furthermore, levels of lipid peroxides in muscle and serum, and muscle edema in the EPC group, were significantly lower than in the NM group. Histological examinations supported these results. These findings suggest that limiting OFR generation by EPC-K1 in the early phase of reoxygenation is more potent than depletion of neutrophils in reducing reperfusion injury.

Experimental stress suppresses recruitment of macrophages but enhanced their P. gingivalis LPS-stimulated secretion of nitric oxide

BACKGROUND

Epidemiological studies have suggested that stress can alter the onset and progression of periodontal disease. However, the mechanisms involved are not clear. The present study was designed to examine whether the functional response of mouse macrophages stimulated by Porphyromonas gingivalis lipopolysaccharide (LPS) is affected by experimental stress, and to investigate the role of corticosterone (CS) in the stress-related effects.

METHODS

Two models of stress were used: emotional (isolation) and physical (cold). We measured thioglycollate-induced macrophage recruitment in vivo, and LPS-induced nitric oxide (NO) secretion by the macrophages in vitro. Two groups of mice were exposed to the stress conditions: isolation or cold. A third group was injected daily with CS, and a fourth group was used as a control (no stress). After 3 days of stress conditions, thioglycollate was injected into the peritoneal cavity. Four days later, peritoneal macrophages were isolated, counted, and cultured. The secretion of NO by the cultured cells was evaluated with and without P. gingivalis LPS stimulation.

RESULTS

The number of cells in the peritoneal lavage of stressed mice was significantly reduced in comparison to macrophages isolated from non-stressed animals. The number of macrophages from CS-treated mice did not differ from controls. NO secretion from unstimulated macrophages did not differ between the stressed and control groups. Stimulation of the macrophages with P. gingivalis LPS significantly enhanced NO secretion by macrophages from the control and stressed animals, but not by the CS-treated group. NO levels secreted by P. gingivalis-stimulated cells from the two stressed groups were significantly higher than the levels secreted by controls, and the isolation group released significantly higher levels than the cold group. Stimulation of the macrophages with P. gingivalis LPS and interferon (IFN)-gamma resulted in enhanced NO secretion in the 4 groups compared to LPS alone, with no significant differences between the groups.

CONCLUSIONS

The results suggest that experimental stress modulates the response of macrophages to inflammatory stimulants, and that CS is not the sole mediator involved. The presence of IFN-gamma in the culture may mask the functional differences induced by stress. The stress-induced upregulation of NO secretion might be involved in the accelerated periodontal destruction in stressed subjects.

Reduced antilisterial activity of TNF-deficient bone marrow-derived macrophages is due to impaired superoxide production

Mice deficient for TNF ligand and receptor type 1 have demonstrated the importance of TNF in the host defense against Listeria monocytogenes. To investigate the particular deficiency of macrophages derived from TNF/lymphotoxin (LT)-alpha(-/-) mice in antilisterial growth control, bone marrow-derived macrophages (BMDM) were used for in vitro infection experiments. After the combined treatment with IFN-gamma and lipopolysaccharide (LPS), production of NO by wild-type (wt) and TNF/LT-alpha(-/-) BMDM was induced to comparable levels, but only wt BMDM controlled L. monocytogenes growth efficiently. Nevertheless, inhibition of NO production led to a remarkable loss of antilisterial activity. This suggests that presence of NO is necessary but not sufficient for L. monocytogenes killing and that elimination of L. monocytogenes requires additional effector molecules. The LPS-inducible superoxide production of TNF/LT-alpha(-/-) BMDM was impaired. Accordingly both scavenging of superoxide and peroxynitrite led to reduced L. monocytogenes killing by wt BMDM. In addition, peroxynitrite was able to kill L. monocytogenes in vitro. Together these findings suggest that the defective host defense of TNF/LT-alpha-deficient mice against L. monocytogenes partially stems from reduced superoxide production of macrophages due to the absence of TNF and imply a function for peroxynitrite, the reaction product of NO and superoxide, in the intracellular killing of L. monocytogenes.

Protective effect of N-acetylcysteine on multiple organ failure induced by zymosan in the rat

BACKGROUND AND METHODS

In the present study, we evaluated the effect of N-acetylcysteine treatment in a nonseptic shock model induced by zymosan in the rat. Animals were randomly divided into eight groups (ten animals in each group). The first group was treated with ip administration of saline solution (0.90% NaCl) and served as the sham group. The second group was treated with ip administration of zymosan (500 mg/kg suspended in saline solution). In the third and fourth groups, rats received ip administration of N-acetylcysteine (40 mg/kg; 1 and 6 hrs after administration of zymosan or saline). In the fifth and sixth groups, rats received ip administration of N-acetylcysteine (20 mg/kg; 1 and 6 hrs after zymosan or saline administration). In the seventh and eighth groups, rats received ip administration of N-acetylcysteine (10 mg/kg; 1 and 6 hrs after zymosan or saline administration). After zymosan or saline injection, animals were monitored for the evaluation of systemic toxicity (conjunctivitis, ruffled fur, diarrhea, and lethargy), loss of body weight, and mortality for 72 hrs. Exudate formation, leukocyte infiltration, nitrate/nitrite production, lung and intestine myeloperoxidase activity and lipid peroxidation, and histologic examination were evaluated at 18 hrs after zymosan administration.

RESULTS

Administration of zymosan in the rat induced acute peritonitis, as assessed by a marked increase in the leukocyte count in the exudate, as well as by an increase in the exudate nitrate/nitrite concentration. Lung and intestine myeloperoxidase activity and lipid peroxidation was significantly increased in zymosan-treated rats. This inflammatory process coincided with the damage of lung and small intestine. Peritoneal administration of zymosan in the rat also induced a significant increase in the plasma levels of nitrite and nitrate and stable metabolites of nitric oxide and in levels of peroxynitrite, as measured by the oxidation of the fluorescent dihydrorhodamine 123 at 18 hrs after zymosan challenge. Immunohistochemical examination demonstrated a marked increase in the immunoreactivity to nitrotyrosine, a specific "footprint" of peroxynitrite, in the lung of zymosan-shocked rats. Pretreatment of zymosan-shocked rats with ip administration of N-acetylcysteine (40, 20, and 10 mg/kg, 1 and 6 hrs after zymosan) prevented the development of peritonitis and reduced peroxynitrite formation in a dose-dependent manner. In addition, ip administration of N-acetylcysteine (40 mg/kg, 1 and 6 hrs after zymosan) was effective in preventing the development of lung and intestine injury and neutrophil infiltration, as determined by myeloperoxidase evaluation.

CONCLUSIONS

Taken together, the present results demonstrate that N-acetylcysteine exerts potent anti-inflammatory effects.

Oh no, not nitric oxide!

Nitric oxide (NO) is a unique, endogenous regulatory molecule that is involved in a wide variety of physiological processes in multiple organ systems. This simple gas functions as a cellular messenger in a broad range of biological activities that include blood pressure regulation, immunomodulation and neurotransmission. It has also been implicated in a number of homeostatic functions in the cardiovascular system: it is a significant determinant of basal vascular tone and, in addition is thought to regulate myocardial contractility and platelet aggregation. Dysregulation of NO mediated effects have been implicated in the pathogenesis of essential hypertension, atherosclerosis, and the hypotension associated with septic shock. This review will focus on these multiple effects of NO in the cardiovascular system.

Effects of macrophage inhibitory factor-A3 (MIF-A3) on cytokine secretion and phagolysosome fusion in murine macrophages

Macrophage inhibitory factor-A3 (MIF-A3) is a fraction derived from Mycobacterium avium serovar 2 (Mav2) that consists of a small amine containing compound (peptide), trehalose and two or three short chain fatty acids. MIF-A3 has been shown to inhibit candidacidal activity of murine thioglycolate-elicited peritoneal-derived macrophages and bovine peripheral blood monocytes, and scavenge reactive oxygen intermediates. In this study, MIF-A3 was evaluated for its effect on secretion of IL-1beta, IL-6, IL-10, TNFalpha and GM-CSF in C57BL/6 murine thioglycolate-elicited peritoneal-derived macrophages, with and without pre-incubation with affinity purified goat anti-MIF-A3 IgG, using ELISA cytokine kit analysis. Results of this study suggest that anti-MIF-A3 IgG does not enhance clearance of Mav2, alter phagocytosis or alter phagosome-lysosome interactions as determined by electron microscopy in Mav2 infected macrophages. MIF-A3 does induce secretion of IL-6, but does not induce secretion of TNFalpha, IL-1beta, and GM-CSF. TNFalpha has been previously shown to reduce growth, while IL-6 has been shown to enhance growth of M. avium. Since IL-6 appears to enhance growth of M. avium and MIF-A3 induces IL-6 secretion, MIF-A3 may be responsible for enhanced intracellular growth in M. avium infections and be a factor in the pathogenesis of M. avium infections.

Immunocytochemical study of the distribution of the free radical scavenging enzymes Cu/Zn superoxide dismutase (SOD1); MN superoxide dismutase (MN SOD) and catalase in the normal human spinal cord and in motor neuron disease

Interest in free radical-mediated mechanisms of motor neuron injury has arisen following the discovery of point mutations in the Cu/Zn superoxide dismutase (SOD1) gene in a proportion of cases of familial motor neuron disease (MND). Evidence is emerging which indicates that oxidative stress may contribute to the pathophysiology of sporadic MND. Free radical scavenging enzymes form a major component of the anti-oxidant defense system. The aim of this study was to compare the distribution and density of immunoreactivity to Cu/Zn SOD. Mn SOD and catalase in the spinal cord of sporadic MND cases (n = 10) compared to normal controls (n = 8). There was abundant expression of Cu/Zn SOD, Mn SOD and catalase in spinal motor neurons, suggesting important roles for these enzymes in neuroprotective pathways in this cell group. In MND cases, there was no evidence in surviving motor neurons of a consistent alteration in the protein expression of any of these enzymes. There was evidence of increased expression of these enzymes in glial cells present in the ventral and intermediate grey matter and degenerating descending motor pathways of the spinal cord in MND cases. The changes observed were more marked in the cervical compared to lumbar spinal segments. Further investigation is required to determine whether these findings represent a compensatory response to a pathophysiological process involving oxidative stress.