Anti-inflammatory effects of recombinant human manganese superoxide dismutase on adjuvant arthritis in rats

Insights into Manganese Superoxide Dismutase and Human Diseases

Redox equilibria and the modulation of redox signalling play crucial roles in physiological processes. Overproduction of reactive oxygen species (ROS) disrupts the body's antioxidant defence, compromising redox homeostasis and increasing oxidative stress, leading to the development of several diseases. Manganese superoxide dismutase (MnSOD) is a principal antioxidant enzyme that protects cells from oxidative damage by converting superoxide anion radicals to hydrogen peroxide and oxygen in mitochondria. Systematic studies have demonstrated that MnSOD plays an indispensable role in multiple diseases. This review focuses on preclinical evidence that describes the mechanisms of MnSOD in diseases accompanied with an imbalanced redox status, including fibrotic diseases, inflammation, diabetes, vascular diseases, neurodegenerative diseases, and cancer. The potential therapeutic effects of MnSOD activators and MnSOD mimetics are also discussed. Targeting this specific superoxide anion radical scavenger may be a clinically beneficial strategy, and understanding the therapeutic role of MnSOD may provide a positive insight into preventing and treating related diseases.

Micronutrients and superoxide dismutase in postmenopausal women with chronic periodontitis: a pilot interventional study

Purpose

The study was aimed at investigating changes in periodontal parameters and superoxide dismutase activity triggered by root surface debridement with and without micronutrient supplementation in postmenopausal women.

Methods

Forty-three postmenopausal chronic periodontitis patients were divided into two groups: group 1 (n=22) were provided periodontal treatment in the form of scaling and root planing (SRP) and group 2 (n=21) patients received SRP along with systemic administration of micronutrient antioxidants. Patients in both groups were subjected to root surface debridement. Group 2 patients also received adjunctive micronutrient antioxidant supplementation. Serum and salivary superoxide dismutase (SOD) activity along with periodontal parameters were recorded at baseline and 3 months after therapy.

Results

Salivary and serum SOD values significantly (P<0.05) improved with periodontal treatment. Improvement in systemic enzymatic antioxidant status along with reduction in gingival inflammation and bleeding on probing (%) sites was significantly greater in group 2 as compared to group 1.

Conclusions

Adjunctive micronutrient supplements reduce periodontal inflammation and improve the status of systemic enzymatic antioxidants in postmenopausal women.

Graphical Abstract

Anti-inflammatory and antihyperalgesic effects of the combination of ibuprofen and hemin in adjuvant-induced arthritis in the Wistar rat

AIM

Although, pharmacological activation of heme oxygenase (HO)-1 has shown to produce ameliorative effects in various experimental models of inflammation, but such beneficial effects have not been observed in adjuvant-induced arthritis. Further, the upregulated activity of HO-1 has been implicated in the pathogenesis of adjuvant arthritis. The present study was designed to investigate the anti-inflammatory and antihyperalgesic effects of the prophylactic use of hemin alone and/or in combination with ibuprofen using adjuvant-induced arthritis in Wistar rat.

METHODS

Arthritis was induced by an intradermal injection of complete Freund's adjuvant (CFA) into left hind paw. Paw volume, thermal hyperalgesia, mechanical allodynia, joint stiffness and mobility behaviors (score) were measured.

RESULTS

Administration of ibuprofen (8.75, 17.5, 35 mg/kg/day, p.o.) and hemin (1, 5, 10 mg/kg/day, i.p.) were significantly effective in suppressing CFA-induced paw oedema, thermal and mechanical hyperalgesia, joint stiffness and mobility. The combination of low doses of ibuprofen (8.75 mg/kg, p.o.) and hemin (1 mg/kg, i.p.) significantly reduced paw volume, thermal and mechanical hyperalgesia, as compared to the individual dose of the ibuprofen and hemin alone.

CONCLUSIONS

Hence, it may be concluded that the prophylactic administration of either hemin produced significantly enhanced anti-inflammatory and analgesic effects. Further, concurrent low dose administration of hemin and ibuprofen produced significantly enhanced anti-inflammatory and analgesic effects, as compared to the either treatment alone, in CFA-induced arthritis in Wistar rats.

Role of nitroso radicals as drug targets in circulatory shock

A vast amount of circumstantial evidence implicates oxygen-derived free radicals (especially, superoxide and hydroxyl radical) and high-energy oxidants [such as peroxynitrite (OONO(-))] as mediators of shock and ischaemia/reperfusion injury. Reactive oxygen species can initiate a wide range of toxic oxidative reactions. These include initiation of lipid peroxidation, direct inhibition of mitochondrial respiratory chain enzymes, inactivation of glyceraldehyde-3 phosphate dehydrogenase, inhibition of membrane sodium/potassium adenosine 5'-triphosphate-ase activity, inactivation of membrane sodium channels and other oxidative modifications of proteins. All these toxicities are likely to play a role in the pathophysiology of shock and ischaemia and reperfusion. Moreover, various studies have clearly shown that treatment with either OONO(-) decomposition catalysts, which selectively inhibit OONO(-), or with superoxide dismutase (SOD) mimetics, which selectively mimic the catalytic activity of the human SOD enzymes, have been shown to prevent in vivo the delayed vascular decompensation and the cellular energetic failure associated with shock and ischaemia/reperfusion injury.

Enhanced intraarticular free radical reactions in adjuvant arthritis rats

One of the reasons of rheumatoid arthritis (RA) development is widely recognized the relation of free radical reactions in tissue injuries. The aim of this study was to evaluate the location where in vivo free radical reactions was enhanced in adjuvant arthritis (AA) model rats using in vivo electron spin resonance (ESR)/nitroxyl spin probe technique. The signal decay after intravenous injection of spin probe was enhanced in AA than that in control and suppressed by the pre-treatment of dexamethasone (DXT). Interestingly, the decay in joint cavity occurred prior to paw swelling of AA and suppressed by a simultaneous injection of free radical scavengers, indicating that the enhancement of free radical reactions in joint cavity of AA rats. This technique would be useful tool to determine the location of the enhanced free radical reactions and evaluate the activity of antioxidant medicine with non-invasive real-time measurement.

Manganese supplementation improves mineral density of the spine and femur and serum osteocalcin in rats

The effect of manganese (Mn) supplementation on bone mineral density (BMD) and bone metabolism parameters was determined in ovariectomized Sprague-Dawley rats. Rats were divided into four groups (OVX, OVX+Mn, sham, sham+Mn) and fed with different intake levels of manganese (adequate 0.001% Mn, supplementation 0.01% Mn) for 12 weeks. BMD of the lumbar vertebrae, femur, and tibia were significantly lowered in ovariectomized rats compared to the sham group. In addition, BMD of the lumbar vertebrae was significantly increased by Mn supplementation in the sham groups. Serum C-telopeptide cross-links of type I collagen (CTx), bone resorption biomarker, alkaline phosphatase (ALP), and bone formation biomarkers were not significantly different among the four groups. However, serum osteocalcin, a more sensitive bone formation biomarker, was significantly increased by Mn supplementation. To summarize, Mn supplementation resulted in increased BMD and bone formation. Based on our findings, more research is needed to better understand the effects of manganese supplementation on bone formation and resorption.

NADPH oxidase is required for neutrophil-dependent autoantibody-induced tissue damage

The contribution of phagocyte-derived reactive oxygen species to tissue injury in autoimmune inflammatory diseases is unclear. Here we report that granulocyte nicotinamide adenine dinucleotide phosphate (NADPH) oxidase crucially contributes to tissue injury in experimental models of the antibody-mediated autoimmune disease epidermolysis bullosa acquisita. Neutrophil cytosolic factor 1-deficient mice lacking functional NADPH oxidase were resistant to skin blistering by the passive transfer of antibodies against type VII collagen. Pharmacological inhibition or deficiency of human NADPH oxidase abolished dermal-epidermal separation caused by autoantibodies and granulocytes ex vivo. In addition, recruitment of granulocytes into the skin was required for tissue injury, as demonstrated by the resistance to experimental blistering of wild-type mice depleted of neutrophils and of CD18-deficient mice. Transfer of neutrophil cytosolic factor 1-sufficient granulocytes into neutrophil cytosolic factor 1-deficient mice demonstrated that granulocytes provide the NADPH oxidase required for tissue damage. Our findings identify granulocyte-derived NADPH oxidase as a key molecular effector engaged by pathogenic autoantibodies and provide relevant targets for prevention of tissue damage in granulocyte-mediated autoimmune diseases.

Alpha-lipoic acid suppresses the development of collagen-induced arthritis and protects against bone destruction in mice

OBJECTIVE

To test the ability of alpha-lipoic acid (LA) to attenuate the development of collagen-induced arthritis (CIA) in mice.

METHODS

Mice were divided into three groups and treated with intraperitoneal administration of LA (10 or 100 mg/kg) or placebo. Clinical, histologic, and biochemical parameters were assessed. Human synovial fibroblasts and peripheral blood mononuclear cells were cocultured in various concentrations of LA to evaluate the effects on osteoclastogenesis.

RESULTS

LA was associated with a dose-dependent reduction of CIA, as well as preventing bone erosion and destructive changes. Intracellular reactive oxygen species in lymphocytes obtained from inguinal lymph nodes, which was significantly higher in CIA than control mice, was significantly reduced in CIA by LA. The concentrations of TNF-alpha, IL-1beta, and IL-6 in the paws, and synovial NF-kappaB binding, all of which were markedly higher in CIA than control mice, were reduced by treatment with LA. In addition, LA inhibited the formation of human osteoclasts in vitro.

CONCLUSION

Amelioration of joint disease by LA was associated with reduction in oxidative stress, as well as inhibition of inflammatory cytokine activation and NF-kappaB DNA binding activity. Moreover, LA inhibited bone destruction in vivo and osteoclastogenesis in vitro. Collectively, these results indicate that LA may be a new adjunctive therapy for rheumatoid arthritis.

On the selectivity of superoxide dismutase mimetics and its importance in pharmacological studies

The list of pathophysiological conditions associated with the overproduction of superoxide expands every day. Much of the knowledge compiled on the role of this radical in disease has been gathered using the native superoxide dismutase enzyme and, more recently, by the use of superoxide dismutase knockout models or transgenic models that overexpress the various isoforms of the enzyme. Although the native enzyme has shown promising anti-inflammatory properties in both preclinical and clinical studies, there were drawbacks and issues associated with its use as a therapeutic agent and pharmacological tool. Based on the concept that removal of superoxide modulates the course of inflammation, synthetic, low-molecular-weight mimetics of the superoxide dismutase enzymes that could overcome some of the limitations associated with the use of the native enzyme have been designed. In this review, we will discuss the advances made using various superoxide dismutase mimetics that led to the proposal that superoxide (and/or the product of its interaction with nitric oxide, peroxynitrite) is an important mediator of inflammation, and to the conclusion that superoxide dismutase mimetics can be utilized as therapeutic agents in diseases of various etiologies. The importance of the selectivity of such compounds in pharmacological studies will be discussed.

Deficiency of NADPH oxidase components p47phox and gp91phox caused granulomatous synovitis and increased connective tissue destruction in experimental arthritis models

Recent studies indicated that the nicotinamide dinucleotide phosphate oxidase (NADPH) oxidase-derived oxygen radicals plays a deleterious role in arthritis. To study this in more detail, gonarthritis was induced in NADPH oxidase-deficient mice. Mice received an intraarticular injection of either zymosan, to elicit an irritant-induced inflammation, or poly-L-lysine coupled lysozyme, to evoke an immune-complex mediated inflammation in passively immunized mice. In contrast to wild-type mice, arthritis elicited in both p47phox(-/-) and gp91(-/-) mice showed more severe joint inflammation, which developed into a granulomatous synovitis. Treatment with either Zileuton or cobra venom factor showed that the chemokines LTB4 and complement C3 were not the driving force behind the aggravated inflammation in these mice. Arthritic NADPH oxidase-deficient mice showed irreversible cartilage damage as judged by the enhanced aggrecan VDIPEN expression, and chondrocyte death. Furthermore, only in the absence of NADPH oxidase-derived oxygen radicals, the arthritic joints showed osteoclast-like cells, tartrate-resistant acid phosphatase (TRAP)-positive/multinucleated cells, extensive bone erosion, and osteolysis. The enhanced synovial gene expression of tumor necrosis factor-alpha, interleukin-1alpha, matrix metalloproteinase (MMP)-3, MMP-9 and receptor activator of NF-kappaB ligand (RANKL) might contribute to the aggravated arthritis in the NADPH oxidase-deficient mice. This showed that the involvement of NADPH oxidase in arthritis is probably far more complex and that oxygen radicals might also be important in controlling disease severity, and reducing joint inflammation and connective tissue damage.

Superoxide dismutase mimetics

In this review we describe the potential role(s) of superoxide in inflammatory disorders.

Therapeutic potential of superoxide dismutase mimetics as therapeutic agents in critical care medicine

Oxidative stress results from an oxidant/antioxidant imbalance, an excess of oxidants, or a depletion of antioxidants. A considerable body of recent evidence suggests that oxidative stress and exaggerated production of reactive oxygen species play a major role in several aspects of septic shock and ischemia and reperfusion. Initiation of lipid peroxidation, direct inhibition of mitochondrial respiratory chain enzymes, inactivation of glyceraldehyde-3-phosphate dehydrogenase, inhibition of membrane Na /K adenosine triphosphatase activity, inactivation of membrane sodium channels, and other oxidative protein modifications contribute to the cytotoxic effect of reactive oxygen species. In addition, reactive oxygen species are potent triggers of DNA strand breakage, with subsequent activation of the nuclear enzyme poly-adenosine 5'-diphosphate ribosyl synthetase, and eventual severe energy depletion of the cells. Pharmacologic evidence suggests that the peroxynitrite-poly-adenosine 5'-diphosphate ribosyl polymerase pathway contributes to the cellular injury in shock and endothelial injury. Treatment with superoxide dismutase mimetics, which selectively mimic the catalytic activity of the human superoxide dismutase enzymes, has been shown to prevent the cellular energetic failure associated with shock and ischemia-reperfusion and to prevent tissue damage associated with these conditions. In this article, we will briefly review the role of superoxide in septic shock and ischemia-reperfusion injury. We hope to present evidence to support the potential development of superoxide dismutase mimetics as novel and effective agents in the area of critical care medicine.

SOD mimetics are coming of age

The list of pathophysiological conditions that are associated with the overproduction of superoxide anions expands every day. The most exciting realization is that there seems to be a similarity between the tissue injury that is observed in various disease states, as superoxide anions produce tissue injury and associated inflammation in all tissues in similar ways. Tissue injury and inflammation form the basis of many disease pathologies, including ischaemia and reperfusion injuries, radiation injury, hyperoxic lung damage and atherosclerosis. This commonality provides a unique opportunity to manipulate numerous disease states with an agent that removes superoxide anions.

Treatment of murine collagen-induced arthritis by ex vivo extracellular superoxide dismutase gene transfer

OBJECTIVE; Superoxide dismutase (SOD) is a potent antiinflammatory enzyme that has received growing attention for its therapeutic potential. This study was undertaken to examine the efficacy of extracellular SOD (EC-SOD) gene therapy in murine collagen-induced arthritis.

METHODS

Embryonic DBA/1 mouse fibroblasts were infected with a recombinant retrovirus expressing human EC-SOD. DBA/1 mice that had been treated with type II collagen were administered subcutaneous injections of 2 x 10(7) EC-SOD-expressing fibroblasts on day 29, when symptoms of arthritis were already present. The severity of arthritis in individual mice was evaluated in a double-blind manner; each paw was assigned a separate clinical score, and hind paw thickness was measured with a caliper. Mice were killed on day 50 for histologic examination of the joints.

RESULTS

High serum concentrations of EC-SOD were maintained for at least 7 days. Mice treated with the transgene exhibited significant suppression of clinical symptoms such as disabling joint swelling, deformity, and hind paw thickness, compared with the untreated group (mean +/- SD maximum clinical score in the untreated and the transgene-treated groups 2.71 +/- 1.08 and 1.35 +/- 1.22, respectively; P < 0.01, and hind paw thickness 3.04 +/- 0.18 mm and 2.56 +/- 0.12 mm, respectively; P < 0.05). Histologic abnormalities, including destruction of cartilage and bone, infiltration of mononuclear cells, and proliferation of synovial cells, were also markedly improved in the EC-SOD-treated mice compared with the control group (histopathologic score 7.50 +/- 1.13 and 4.13 +/- 1.88 in the untreated and transgene-treated groups, respectively; P < 0.05).

CONCLUSION

These results indicate that EC-SOD gene transfer may be an effective form of therapy for rheumatoid arthritis.

Superoxide regulation of endothelin-converting enzyme

Reactive oxygen species (ROS) act as signaling molecules in the cardiovascular system, regulating cellular proliferation and migration. However, an excess of ROS can damage cells and alter endothelial cell function. We hypothesized that endogenous mechanisms protect the vasculature from excess levels of ROS. We now show that superoxide can inhibit endothelin-converting enzyme activity (ECE) and decrease endothelin-1 synthesis. Superoxide inhibits ECE but hydrogen peroxide and nitric oxide do not. Superoxide inhibits ECE by ejecting zinc from the enzyme, and the addition of exogenous zinc restores enzymatic activity. Superoxide may inhibit other zinc metalloproteinases by a similar mechanism and may thus play an important role in regulating the biology of blood vessels.

Effects on bone loss of manganese alone or with copper supplement in ovariectomized rats. A morphometric and densitomeric study

OBJECTIVE

The aim of this study was to examine the effect of manganese (Mn) alone and with the addition of copper (Cu) in the inhibition of osteopenia induced by ovariectomy (OVX) in rats. STUDY CONDITIONS: Four lots of 100-day-old female Wistar rats were divided into experimental groups of 15 each. One group received a diet supplemented with 40 mg/kg of Mn per kilogram of feed (OVX+Mn). The second group received the same diet as the first, but with an additional 15 mg/kg of copper (OVX+Mn+Cu). The third group of 15 OVX and the fourth group of 15 Sham-OVX received no supplements. At the conclusion of the 30-day experiment, the rats were slaughtered and their femurs and fifth lumbar vertebrae were dissected. Femoral and vertebral length were measured with caliper and bones were weighed on a precision balance. The bone mineral content (BMC) and bone density (BMD) of the femur (F-BMC, mg and F-BMD, mg/cm(2)) and the fifth lumbar vertebra (V-BMC, mg and V-BMD, mg/cm(2)) were measured separately with dual energy X-ray absorptiometry.

RESULTS

The F-BMD, mg/cm(2) was lower in the OVX than in the Sham-OVX group (P<0.0001) and in the other two groups receiving mineral supplements (P<0.005 in both). F-BMC, mg was significantly lower in the OVX group than in the other three (P<0.0001 in all cases). Calculations for V-BMC, mg and V-BMD, mg/cm(2) are similar to findings in the femur.

CONCLUSIONS

These data show that a Mn supplement is an effective inhibitor of loss of bone mass after OVX, both on the axial and the peripheral levels, although this effect is not enhanced with the addition of Cu.

Anti-inflammatory activity of superoxide dismutase conjugated with sodium hyaluronate

Superoxide dismutase (SOD) from bovine erythrocytes was conjugated with sodium hyaluronate (HA) with a mean molecular weight of 10(6) to have greater anti-inflammatory activity in vivo. Amino groups of SOD were coupled with carboxyl groups in the hyaluronate molecule using 1-ethyl-3-(3-dimethylaminopropyl)carbodiimide. The HA-SOD conjugate was composed of 1.5 mol of SOD molecule per 1 mol of hyaluronate on the average, and retained 70% of the activity of unmodified SOD. The conjugate was essentially non-immunogenic in mice, and exhibited much higher anti-inflammatory activities than HA or SOD in models of inflammatory diseases such as ischemic oedema of the foot-pad in mice, carrageenin-induced pleurisy and adjuvant arthritis in rats.

Role of endotoxin-like contaminants in the apparent anti-inflammatory activity of bovine superoxide dismutase

Bovine CuZn superoxide dismutase (SOD: 1, 3 and 10 mg/kg) dose-dependently reduced carrageenan-induced paw edema in rats when administered intravenously 30 min before irritant injection. However, heat-treated SOD (10 mg/kg) was as effective as native SOD (10 mg/kg) although the enzymic activity was reduced to 9.7%. Examination of the contaminants of the native SOD revealed a fairly large amount of endotoxin-like activity, 47 ng as Escherichia coli endotoxin per mg, and 59.6% of this activity remained after heat treatment. Bovine CuZn SOD (1, 3 and 10 mg/kg), which contained negligible endotoxin-like materials and 1.5 times more enzyme units, had no effect on edema under the same conditions. Furthermore, Escherichia coli endotoxin (10, 100 and 1000 ng/kg) reduced edema dose-dependently. These results suggest that contamination by endotoxin-like materials is responsible for the anti-inflammatory action of the SOD preparation we observed. Hence, the anti-inflammatory action of contaminating endotoxin-like materials may lead to misinterpretation as a protective effect of SOD unless stringent precautions are taken against endotoxin-like contaminants in the SOD under examination.