Psoriasis: current concepts and new approaches to therapy

Therapeutic evaluation of HIV transduction basic domain-conjugated superoxide dismutase solution on suppressive effects of the formation of peroxynitrite and expression of COX-2 in murine skin

Background

Homeostasis of reactive oxygen species (ROS) in the skin is regulated by antioxidant defenses. The inflammatory states of skin diseases which range from acute rashes to chronic conditions are related to the level of ROS. The involvement of superoxide dismutase (SOD) in restoring the antioxidant capacity can then neutralize the inflammatory response.

Results

We found that denatured Tat-SOD formulated in an aqueous medium could be delivered into mouse skin and the penetration signals of Tat-SOD were detected in the epidermis and dermis. According to immunohistochemical staining, Tat-SOD successfully suppressed inflammation induced by 12-O-tetradecanoylphorbol-13-acetate (TPA), the expression of sodium nitroferricyanide (SNP)-induced cyclooxygenase-2 (COX-2), and the production of nitrotyrosine proteins. In nerve growth factor (NGF) induced differentiated PC12 pheochromocytoma cells, we demonstrated that the denatured Tat-SOD regained its antioxidant activity and effectively protected PC12 cells from DNA fragmentation induced by paraquat. Using a luciferase reporter assay, the data was shown Tat-SOD protected PC12 cells from ROS damage, through suppression of COX-2 or nuclear factor-κB (NF-κB) activity occurred at the transcriptional level.

Conclusion

We showed that Tat-SOD inhibited SNP-induced COX-2 expression similarly to celecoxib and prevented the formation of peroxynitrite as 2-phenyl-4,4,5,5-tetramethylimidazoline-1-oxyl-3-oxide. The results suggest that denatured Tat-SOD solution may perform potential protein therapy for patients suffering from disorders related to ROS.

Zinc and copper levels in Iranian patients with psoriasis: a case control study

Zinc and copper are important cofactors and modulators of many critical biological functions in many dermatological diseases including psoriasis. Studies must be performed in different societies to organize a governmental health organization nutritional program. Due to the lack of information related to these trace elements in Iranian psoriasis patients, the aim of this observational case-control study was to compare the serum zinc and copper levels and the zinc/copper ratio in psoriatic patients and healthy volunteers in Northern Iran. Zinc and copper serum concentrations were assayed in 25 selected psoriasis patients and compared with sex- and age-matched healthy volunteers. The mean copper level in psoriatic patients was significantly higher than in healthy volunteers (p = 0.003), but no significant difference was observed in the zinc concentration between the two groups (p = 0.57). This study was the first one among Iranian society, and no information have been published in the field yet. The results bring some new information related to Iranian psoriatic patients in contrast to some other studies in different region so that preventive programs could be made in this regard particularly for Iranian population. With respect to the high copper concentration in the Iranian psoriatic population, using copper-chelating agents, such as penicillamine may be suggested for Iranian patients following further comprehensive investigations.

The combined effect of topical CX-659S, a novel diaminouracil derivative, with topical corticosteroid on the three types of allergic responses in mice or guinea pigs

CX-659S ((S)-6-amino-5-(6-hydroxy-2,5,7,8-tetramethylchroman-2-carboxamido)-3-methyl-1-phenyl-2,4(1H,3H)-pyrimidinedione), a newly discovered anti-inflammatory compound, exerts inhibitory effects against picryl chloride-, oxazolone-, and dinitrochlorobenzene-induced acute contact hypersensitivity responses (CHRs) characterized by Th1-type reactions. Furthermore, this compound suppressed chronic CHRs characterized by Th2-type reactions, which is well known to mimic many, if not all, events occurring within the lesional skin of patients with atopic dermatitis (AD). The present study was conducted to determine the combined effect of topical CX-659S with topical corticosteroid on immediate type (ITR), late type (LTR), and delayed type hypersensitivity (DTHR) allergic reactions that are involved in AD. An ineffective dose of CX-659S (0.03 mg/ear) combined with betamethasone valerate (BV) significantly potentiated inhibitory activity of BV alone (0.1 micro g/ear and 0.3Shizuokag/ear) on both the ITR and the LTR in mice with the ovalbumin (OVA)-induced biphasic cutaneous reaction. Furthermore, the combined effect of CX-659S with BV was also observed on dinitrochlorobenzene (DNCB)-induced DTHR in guinea pigs. These results indicate that CX-659S has a combined effect with corticosteroids on every ITR, LTR, and DTHR. Proper treatment with corticosteroids for a safe and effective treatment of AD is needed. Thus, the combination therapy of topical CX-659S with topical corticosteroid would be one of the potential approaches for devising a proper treatment with corticosteroids.

Oxidative stress and its role in skin disease

Skin is a major target of oxidative stress due to reactive oxygen species (ROS) that originate in the environment and in the skin itself. ROS are generated during normal metabolism, are an integral part of normal cellular function, and are usually of little harm because of intracellular mechanisms that reduce their damaging effects. Antioxidants attenuate the damaging effects of ROS and can impair and/or reverse many of the events that contribute to epidermal toxicity and disease. However, increased or prolonged free radical action can overwhelm ROS defense mechanisms, contributing to the development of cutaneous diseases and disorders. Although ROS play a role in diseases such as skin cancer, their biological targets and pathogenic mode of action are still not fully understood. In addition, strategies useful in the therapeutic management of ROS action in human skin are still lacking. This review is intended to give investigators an introduction to ROS, antioxidants, two skin disorders influenced by ROS action (skin cancer and psoriasis), and relevant model systems used to study ROS action.

Antioxidant potential of propylthiouracil in patients with psoriasis

OBJECTIVE

There is growing evidence supporting the reactive oxygen species (ROS) in the pathogenesis of psoriasis. Propylthiouracil(PTU), an antithyroid drug, has been shown to have beneficial effects on psoriasis. The aim of this study was to investigate both disturbances in oxidant/antioxidant system in psoriasis and whether PTU, shown to have immunomodulatory effects and antioxidant potential, has effects on oxidant/antioxidant system and clinical improvement in psoriatics.

DESIGN AND METHODS

Malondialdehyde (MDA), end product of lipid peroxidation, superoxide dismutase (SOD) and glutathione peroxidase (GSH-Px), and antioxidant enzymes were measured in plasma, erythrocytes and skin biopsies of psoriatics who were resistant to conventional therapy before and after 8 weeks of oral treatment with PTU (300 mg/day) or PTU/thyroxine (25 microg/day- to prevent possible hypothyroidism). The same parameters were also studied in healthy controls. Psoriasis Area and Severity Index (PASI) scores were used to evaluate the severity of the disease, and routine analyses and thyroid function tests were measured during the study.

RESULTS

Increased baseline MDA in all samples were found to be lower. In addition baseline SOD and GSH-Px in skin and erythrocytes were also lower. The increased plasma SOD levels in skin and erythrocytes of the study groups was found to be higher and lower,respectively in all patients after the treatment. No tissue parameters or erythrocyte GSH-Px were different from control levels at the end of the study. Significant clinical improvement and decreased PASI scores were observed in all patients. Post treatment TSH levels were higher in all patients, but these levels were within the reference range and none had clinical hypothyroidism.

CONCLUSION

These findings may provide some evidence for a potential role of increased lipid peroxidation and decreased antioxidant activity in psoriasis. PTU may be considered as treatment model in psoriasis, in particular for resistant cases, because of its antioxidant potential, and also antiproliferative and immunomodulatory effects.

CX-659S: a novel diaminouracil derivative that has antioxidative and acute anti-inflammatory activities

We investigated the antioxidative activities and the effects on acute inflammation in mice of a novel diaminouracil derivative, CX-659S ((S)-6-amino-5-(6-hydroxy-2,5,7,8-tetramethylchroman-2-carboxamido)-3-methyl-1-phenyl-2,4(1H,3H)-pyrimidinedione). CX-659S showed potent scavenging activities against the hydroxyl radical and peroxynitrite and inhibited lipid peroxidation in rat brain homogenates in vitro. Topically applied CX-659S dose-dependently inhibited arachidonic acid- and 12-O-tetradecanoylphorbol 13-acetate (TPA)-induced ear edema in mice. Consistent with its antioxidative properties in vitro, CX-659S dramatically attenuated the accumulation of lipid peroxides in the mouse ear elicited by repeated application of TPA. Previously, we reported the effectiveness of CX-659S against contact hypersensitivity reactions in both mouse and guinea pig models. These present results further suggest the therapeutic potential of CX-659S for acute skin inflammation that may involve oxidative tissue damage.

Oxyradical-mediated clastogenic plasma factors in psoriasis: increase in clastogenic activity after PUVA

Psoriasis is a common skin disorder characterized by hyperproliferation and incomplete differentiation of epidermal keratinocytes. Psoralen plus UVA (PUVA) is one of the treatments proposed for this disease. We had reported previously that exposure of regular blood cultures from healthy donors to PUVA leads to chromosomal breakage via the formation of transferable clastogenic materials, a phenomenon inhibitable by superoxide dismutase. In the present paper we show that these clastogenic factors (CF) are also formed in vivo. The CF were found in about 50% of the psoriasis patients studied (14 out of 31). In PUVA-treated psoriasis patients, the clastogenic activity of the plasma increased significantly between the first and the last (16th) exposure to PUVA. We hypothesize that CF formation in psoriasis is similar to that in other diseases accompanied by oxidative stress, in particular chronic inflammatory diseases with autoimmune reactions such as lupus erythematosus, progressive systemic sclerosis, rheumatoid arthritis and others. Increased superoxide production by phagocytes, formation of lipid peroxidation products and release of cytokines are considered to be responsible for the superoxide-stimulating and chromosome-damaging properties of patients' plasma. During PUVA therapy, superoxide generated via the interaction of psoralen with UVA may contribute to CF formation in addition to superoxide from inflammatory cells. An increased risk of cancer and leukemia is observed in diseases accompanied by CF formation. Therefore CF may contribute to the well-known risk of photocarcinogenesis by PUVA therapy. This additional risk may be preventable by antioxidants and superoxide scavengers.

Eicosanoids, fatty acids and neutrophils: their relevance to the pathophysiology of disease

PUFA and their eicosanoid metabolites are potent biological modifiers. They have beneficial effects in a number of diseases, which may result in part from their direct actions on neutrophils as well as from their ability to modulate eicosanoid biosynthesis. A consideration of their interactions with other cell types, e.g. lymphocytes and macrophages, is beyond the scope of this review. Small alterations in structure can result in large changes in the neutrophil response. This will have important implications for the further development and use of fatty acids for therapeutic purposes.