Keratinocyte superoxide generation

Evaluation of Lactocare® Synbiotic Administration on the Serum Electrolytes and Trace Elements Levels in Psoriasis Patients: a Randomized, Double-Blind, Placebo-Controlled Clinical Trial Study

BACKGROUND

Despite the exact etiopathogenesis of psoriasis remains unknown, the increasing or decreasing of some trace elements and oxidative stress status are considered to play a role. In this study, the effect of Lactocare® synbiotic on the serum levels of trace elements including Zn, Cu, Mg, Na, Fe, P, Ca, and K in the patients with mild to moderate psoriasis was investigated.

METHODS

Sixty-four patients with mild to moderate psoriasis were included. Patients were randomly divided into treatment (n═32) and control (n═32) groups. The treatment group received Lactocare® and the control group received a placebo (two times daily for 12 weeks). Eight patients from the intervention group and 18 patients from the control group discontinued the study because of the recent COVID-19 condition. For routine trace element analysis, the blood samples were collected from all patients at the baseline as well as week 12 post-treatment. The serum was then isolated and the serum levels of trace elements including Fe, K, Ca, Mg, P, Zn, Na, and Cu were measured using an automatic electrolyte analyzer. For confirmation of the effect of Lactocare® on the alteration of serum levels of trace elements, intra-group analysis was performed at two interval times: baseline and week 12 post-treatment.

RESULTS

The serum levels of K, P, and Ca in the placebo group were significantly higher than that of the treatment group at baseline. Serum levels of Zn and Ca were significantly higher in the treatment group compared to the placebo group at week 12 post-treatment. Moreover, a significantly lower serum level of K, P, and Ca in the treatment group at the baseline compared to the placebo group was compensated on week 12 post-treatment. Intra-group analysis in the treatment group showed that the serum levels of Fe, Ca, Mg, P, Zn, and Na was significantly increased at week 12 post-treatment compared to baseline levels. Whereas, intra-group analysis in the control group showed only Ca has a significant difference between baseline and week 12 post-treatment.

CONCLUSION

The serum levels of Fe, Zn, P, Mg, Ca, and Na are increased significantly 12 weeks after oral administration of Lactocare® in psoriatic patients. The serum level of Fe and Cu is affected by sex at pre- and post-treatment. This study supports the concept that Lactocare® exerts beneficial effects in the gastrointestinal tract to improve mineral absorption in psoriatic patients.

On the Anti-Cancer Effect of Cold Atmospheric Plasma and the Possible Role of Catalase-Dependent Apoptotic Pathways

Cold atmospheric plasma (CAP) is a promising new agent for (selective) cancer treatment, but the underlying cause of the anti-cancer effect of CAP is not well understood yet. Among different theories and observations, one theory in particular has been postulated in great detail and consists of a very complex network of reactions that are claimed to account for the anti-cancer effect of CAP. Here, the key concept is a reactivation of two specific apoptotic cell signaling pathways through catalase inactivation caused by CAP. Thus, it is postulated that the anti-cancer effect of CAP is due to its ability to inactivate catalase, either directly or indirectly. A theoretical investigation of the proposed theory, especially the role of catalase inactivation, can contribute to the understanding of the underlying cause of the anti-cancer effect of CAP. In the present study, we develop a mathematical model to analyze the proposed catalase-dependent anti-cancer effect of CAP. Our results show that a catalase-dependent reactivation of the two apoptotic pathways of interest is unlikely to contribute to the observed anti-cancer effect of CAP. Thus, we believe that other theories of the underlying cause should be considered and evaluated to gain knowledge about the principles of CAP-induced cancer cell death.

The role of glutathione and glutathione peroxidase in regulating cellular level of reactive oxygen and nitrogen species

Glutathione (GSH) and GSH/glutathione peroxidase (GPX) enzyme system is essential for normal intracellular homeostasis and gets disturbed under pathophysiologic conditions including endothelial dysfunction. Overproduction of reactive oxidative species (ROS) and reactive nitrogen species (RNS) including superoxide (O₂^•-), and the loss of nitric oxide (NO) bioavailability is a characteristic of endothelial dysfunction. The GSH/GPX system play an important role in eliminating ROS/RNS. Studies have provided important information regarding the interactions of ROS/RNS with the GSH/GPX in biological systems; however, it is not clear how this cross talk affect these reactive species and GSH/GPX enzyme system, under physiologic and oxidative/nitrosative stress conditions. In the present study, we developed a detailed endothelial cell kinetic model to understand the relationship amongst the key enzyme systems including GSH, GPX, peroxiredoxin (Prx) and reactive species, such as hydrogen peroxide (H₂O₂), peroxynitrite (ONOO^-), and dinitrogen trioxide (N₂O₃). Our simulation results showed that the alterations in the generation rates of O₂^•- and NO led to the formation of a wide range of ROS and RNS. Simulations performed by varying the ratio of O₂^•- to NO generation rates as well as GSH and GPX concentrations showed that the GPX reducing capacity was dependent on GSH availability, level of oxidative/nitrosative stress, and can be attributed to N₂O₃ levels, but not to H₂O₂ and ONOO^-. Our results showed that N₂O₃ mediated switch-like depletion in GSH and the incorporation of Prx had no considerable effect on the ROS/RNS species other than ONOO^- and H₂O₂. The analysis presented in this study will improve our understanding of vascular diseases in which the levels and oxidation states of GSH, GPX and/or Prx are significantly altered and pharmacological interventions show limited benefits.

Thiol/disulphide balance in patients with psoriasis

Introduction

Psoriasis is a common chronic inflammatory skin disease with unknown etiopathogenesis.

Aim

To examine the thiol/disulfide balance in psoriasis patients and to compare the results with a healthy control group.

Material and methods

Eighty patients with psoriasis and 80 healthy individuals who were age- and gender-matched with these patients were included in this study. Serum native thiol, disulfide and total thiol levels were measured by a new automated method developed by Erel and Neselioglu. Disulphide/total thiol, disulphide/native thiol and native thiol/total thiol were calculated.

Results

While there was no statistically significant difference in terms of disulphide levels (SS) between the patient and control groups (p > 0.05), there were significant differences in terms of total thiol and native thiol (SH) levels, SS/SH, SS/total thiol and SH/total thiol ratios between the patient and control groups (p < 0.05). There was a statistically significant relationship between duration of the disease and the disulfide/native thiol ratio (p > 0.05).

Conclusions

In recent years, there have been few studies on the role of oxidative stress in the etiopathogenesis of psoriasis. In this study, we investigated in psoriasis patients, thiol/disulfide balance as a new oxidative stress marker. The results were compared with a healthy control group. Our results showed that thiol/disulphide balance shifted towards disulphide in psoriasis patients. This is important as a finding that supports the role of oxidative stress in the pathogenesis of psoriasis.

Urinary Biopyrrins: A New Marker of Oxidative Stress in Psoriasis

Background:

Psoriasis is a common chronic, relapsing, immune-mediated disease involving skin and joints of genetically predisposed individuals. Oxidative stress has been found to play many important roles in cellular damage and loss of function in a number of tissues and organs and is believed to contribute to the pathogenesis of a variety of diseases. Urinary biopyrrin levels have gained attention as an indicator of oxidative stress.

Aim and Objective:

To measure urinary biopyrrins excretion as a marker of oxidative stress in psoriasis.

Patients and Methods:

This case–control study was carried out on 85 subjects; 55 cases with chronic plaque psoriasis and 30 age, gender and body mass index-matched normal subjects as a control group. Urinary biopyrrin levels were measured using enzyme immunoassay.

Results:

There was a highly significant difference between cases and controls regarding urinary biopyrrins level (P < 0.001). There was significant positive correlation between biopyrrins level and both the age of cases (r = 0.28, P = 0.01) and psoriasis area and severity index score (r = 0.99, P < 0.001).

Conclusion:

Urinary biopyrrins are increased in patients with psoriasis, and the level is correlated with disease severity. Further large-scale studies involving different ages and different clinical varieties of the disease are needed to expand and validate current findings. The clinical usefulness of antioxidants in psoriasis treatment needs to be evaluated in future research. Furthermore, the value of biopyrrins as biomarkers for monitoring response to therapy needs to be evaluated.

Comparison of levels of serum copper, zinc, albumin, globulin and alkaline phosphatase in psoriatic patients and controls: A hospital based casecontrol study

BACKGROUND

Psoriasis is a chronic, immune-mediated skin disease with unknown etiology, with an epidermal turnover time of <10 days compared to a normal turnover time of 4-8 weeks. This epidermal hyperproliferation accounts for many of the metabolic abnormalities including alteration in the serum levels of proteins and some trace elements.

AIM

The aim was to detect any statistically significant difference in the serum levels of zinc, copper, albumin, globulin and alkaline phosphatase between psoriasis patients and healthy controls.

MATERIALS AND METHODS

Hundred cases of psoriasis and 100 age and sex matched controls were enrolled in a hospital based case-control study. The serum levels of zinc, copper, albumin, globulin and alkaline phosphatase were calculated and compared among the cases and controls and evaluated statistically.

RESULTS

Serum zinc levels were significantly low in the psoriasis group as compared with controls (mean 80.028 μg/dl vs. 109.179 μg/dl, P < 0.0001). Serum copper levels were significantly raised among cases as compared with controls (mean 167.317 μg/dl vs. 133.884 μg/dl P < 0.0001). Serum albumin levels were significantly decreased (3.762 g/dl vs. 4.103 g/dl, P < 0.001), whereas serum globulin levels were raised (3.296 g/dl vs. 2.596 g/dl, P = 0.0014) among cases as compared with controls, respectively. Serum alkaline phosphatase levels were comparable between the two groups.

CONCLUSION

The results of this study show significant alterations in the serum levels of copper, zinc, albumin, and globulin in psoriatic patients. This paper aims at highlighting the possible role of trace metals copper and zinc in the aetiopathogenesis of psoriasis and also provides a proposed interplay of factors involved in the pathogenesis of psoriasis.

Reactive oxygen species in psoriasis and psoriasis arthritis: relevance to human disease

Psoriasis (Ps) is a chronic, immune-mediated, skin inflammatory disease affecting up to 3% of the population worldwide. Different environmental triggers initiate this complex multifactorial syndrome. Many individuals affected by Ps (6-26%) develop inflammatory disease in other organs, often in the joints as in psoriasis arthritis (PsA). Animal models that reflect the typical Ps syndrome, including both skin and joint pathology as in Ps and PsA, are valuable tools for dissecting disease pathways leading to clinical manifestations. In this context, we developed a new acute Ps and PsA-like disease model that appears after exposure to Saccharomyces cerevisiae mannan in certain mouse strains. The disease was found to be triggered by mannan-activated macrophages, leading to the activation of a pathogenic interleukin-17 pathway involving innate lymphocytes. Interestingly, the production of reactive oxygen species protected the mice from the triggering of this pathway and ameliorated Ps and PsA development.

Ethyl ferulate, a component with anti-inflammatory properties for emulsion-based creams

Ethyl ferulate (FAEE) has been widely studied due to its beneficial heath properties and, when incorporated in creams, shows a high sun protection capacity. Here we aimed to compare FAEE and its precursor, ferulic acid (FA), as free radical scavengers, inhibitors of oxidants produced by leukocytes and the alterations in rheological properties when incorporated in emulsion based creams. The cell-free antiradical capacity of FAEE was decreased compared to FA. However, FAEE was more effective regarding the scavenging of reactive oxygen species produced by activated leukocytes. Stress and frequency sweep tests showed that the formulations are more elastic than viscous. The viscoelastic features of the formulations were confirmed in the creep and recovery assay and showed that the FAEE formulation was less susceptive to deformation. Liberation experiments showed that the rate of FAEE release from the emulsion was slower compared to FA. In conclusion, FAEE is more effective than FA as a potential inhibitor of oxidative damage produced by oxidants generated by leukocytes. The rheological alterations caused by the addition of FAEE are indicative of lower spreadability, which could be useful for formulations used in restricted areas of the skin.

Redefining the major contributors to superoxide production in contracting skeletal muscle. The role of NAD(P)H oxidases

The production of reactive oxygen and nitrogen species (RONS) by skeletal muscle is important as it (i) underlies oxidative damage in many degenerative muscle pathologies and (ii) plays multiple regulatory roles by fulfilling important cellular functions. Superoxide and nitric oxide (NO) are the primary radical species produced by skeletal muscle and studies in the early 1980s demonstrated that their generation is augmented during contractile activity. Over the past 30 years considerable research has been undertaken to identify the major sites that contribute to the increased rate of RONS generation in response to contractions. It is widely accepted that NO is regulated by the nitric oxide synthases, however the sites that modulate changes in superoxide during exercise remain unclear. Despite the initial indications that the mitochondrial electron transport chain was the predominant source of superoxide during activity, with the development of analytical methods a number of alternative potential sites have been identified including the NAD(P)H oxidases, xanthine oxidase, cyclooxygenases, and lipoxygenases linked to the activity of the phospholipase A2 enzymes. In the present review we outline the subcellular sites that modulate intracellular changes in superoxide in skeletal muscle and based on the available experimental evidence in the literature we conclude that the NAD(P)H oxidases are likely to be the major superoxide generating sources in contracting skeletal muscle.

Transfer of a two-tiered keratinocyte assay: IL-18 production by NCTC2544 to determine the skin sensitizing capacity and epidermal equivalent assay to determine sensitizer potency

At present, the identification of potentially sensitizing chemicals is carried out using animal models. However, it is very important from ethical, safety and economic point of view to have biological markers to discriminate allergy and irritation events, and to be able to classify sensitizers according to their potency, without the use of animals. Within the Sens-it-iv EU Frame Programme 6 funded Integrated Project (LSHB-CT-2005-018681), a number of in vitro, human cell based assays were developed which, when optimized and used in an integrated testing strategy, may be able to distinguish sensitizers from non-sensitizers. This study describes two of these assays, which when used in a tiered strategy, may be able to identify contact sensitizers and also to quantify sensitizer potency. Tier 1 is the human keratinocyte NCTC2544 IL-18 assay and tier 2 is the Epidermal Equivalent potency assay. The aim of this study is to show the transferability of the two-tiered approach with training chemicals: 3 sensitizers (DNCB, resorcinol, pPD) and 1 non sensitizer (lactic acid) in tier 1 and 2 sensitizers with different potency in tier 2 (DNCB; extreme and resorcinol; moderate). The chemicals were tested in a non-coded fashion. Here we describe the transferability to naïve laboratories, the establishment of the standard operating procedure, critical points, acceptance criteria and project management. Both assays were successfully transferred to laboratories that had not performed the assays previously. The two tiered approach may offer an unique opportunity to provide an alternative method to the Local Lymph Node Assay (LLNA). These assays are both based on the use of human keratinocytes, which have been shown over the last two decades, to play a key role in all phases of skin sensitization.

Role of cellular oxidative stress and cytochrome c in the pathogenesis of psoriasis

Oxidative-free radicals and apoptosis have linked to chronic skin diseases. Higher levels of oxidative radicals and the release of mitochondrial cytochrome c may have a role in the pathogenesis of psoriasis. We investigated the possible role of cellular oxidative stress and release of cytochrome c of mitochondria in the pathogenesis of psoriasis. Disease severity was assessed by psoriasis area severity index score (PASI) of 55 psoriasis patients, they grouped as mild (11), moderate (20) and severe (24), also 20 healthy individuals used as controls. All groups were subjected for serum malondialdehyde (MDA), nitric oxide (NO·), superoxide dismutase (SOD), catalase (CAT), total antioxidant status (TAS) and serum cytochrome c concentrations. We found that, (1) Severity wise increase in MDA and NO·, and decrease in SOD, CAT and TAS levels in all patients with different degrees of psoriasis; (2) PASI showed positive correlation with the increase in MDA and NO·, and negatively with decreased SOD, CAT and TAS levels; (3) significant increase in cytochrome c level was observed among psoriasis patients which showed negative correlation to MDA and NO· levels in mild and positively with moderate and severe groups. The release of mitochondrial cytochrome c indicates the induction of apoptosis mediated via oxidative stress which ultimately plays role in the pathogenesis of psoriasis.

Calcium fructoborate--potential anti-inflammatory agent

Calcium fructoborate is a boron-based nutritional supplement. Its chemical structure is similar to one of the natural forms of boron such as bis-manitol, bis-sorbitol, bis-fructose, and bis-sucrose borate complexes found in edible plants. In vitro studies revealed that calcium fructoborate is a superoxide ion scavenger and anti-inflammatory agent. It may influence macrophage production of inflammatory mediators, can be beneficial for the suppression of cytokine production, and inhibits progression of endotoxin-associated diseases, as well as the boric acid and other boron sources. The mechanisms by which calcium fructoborate exerts its beneficial anti-inflammatory effects are not entirely clear, but some of its molecular biological in vitro activities are understood: inhibition of the superoxide within the cell; inhibition of the interleukin-1β, interleukin-6, and nitric oxide release in the culture media; and increase of the tumor necrosis factor-α production. Also, calcium fructoborate has no effects on lipopolysaccharide-induced cyclooxygenase-2 protein express. The studies on animals and humans with a dose range of 1-7 mg calcium fructoborate (0.025-0.175 mg elemental boron)/kg body weight/day exhibited a good anti-inflammatory activity, and it also seemed to have negligible adverse effect on humans.

Nitric oxide and malondialdehyde levels in plasma and tissue of psoriasis patients

BACKGROUND

The pathogenesis of psoriasis has not been known exactly yet. Recently, it has been suggested that increased reactive oxygen species (ROS) such as nitric oxide (NO) and malondialdehyde (MDA) may play a part in the pathogenesis of various skin diseases, including psoriasis.

OBJECTIVES

In this study, we aimed to investigate the role of ROS in the pathogenesis of psoriasis.

METHODS

A convenience sample of 23 patients with psoriasis and 23 healthy subjects consented to participate in the study. Plasma NO and MDA levels were measured in all participants. Psoriasis area and severity index (PASI) and tissue levels of MDA on lesional and non-lesional skin regions of psoriasis patients were measured. In addition, the correlation between age, gender with plasma NO, plasma MDA and tissue MDA was assessed.

RESULTS

Plasma levels of NO and MDA in psoriasis patients (135.8 μmol/L, 4.33 μmol/L, respectively) were statistically significantly higher than those in controls (33.6 μmol/L, 2.03 μmol/L, respectively). Tissue levels of MDA in lesional tissues (49.18 nmol/gr) were significantly higher than those in non-lesional tissues (28.41 nmol/gr). A significant correlation was not found between the PASI and levels of NO and MDA. In addition, a significant negative correlation was found between the plasma NO levels and age.

CONCLUSION

NO and MDA levels are elevated in psoriasis patients, which may indicate that oxidative stress plays an important role in the aetiopathogenesis of psoriasis.

Role of oxidative stress in various stages of psoriasis

Psoriasis is a chronic inflammatory, proliferative skin disease characterized by pathological skin lesions due to various exogenous and endogenous factors. It is associated with a number of biochemical and immunological disturbances. Recently, it has been suggested that increased reactive oxygen species (ROS) production and compromised function of antioxidant system may be involved in the pathogenesis of this disease. In the present study, 90 psoriasis patients were selected. Disease severity was assessed by psoriasis area severity index score and grouped as mild, moderate and severe (each group consists of 30 subjects) and compared with 30 healthy controls. Serum levels of malondialdehyde, nitric oxide end products and the activities of antioxidant enzymes such as erythrocyte-superoxide dismutase, catalase and total antioxidant status were investigated in these groups/subjects. As compared to controls, we found severitywise significantly increased serum malondialdehyde, nitric oxide end products with decrease in erythrocyte-superoxide dismutase activity, catalase activity and total antioxidant status in patients with psoriasis suggesting worsening of the disease. It seems to be linked with the enhancement of Reactive Oxygen Species production and decreased antioxidant potential in psoriasis.

Extremely low frequency electromagnetic fields modulate expression of inducible nitric oxide synthase, endothelial nitric oxide synthase and cyclooxygenase-2 in the human keratinocyte cell line HaCat: potential therapeutic effects in wound healing

BACKGROUND

Extremely low frequency (ELF) electromagnetic fields (EMF) are known to produce a variety of biological effects. Clinical studies are ongoing using EMF in healing of bone fractures and skin wounds. However, little is known about the mechanisms of action of ELF-EMF. Several studies have demonstrated that expression and regulation of nitric oxide synthase (NOS) and cyclooxygenase-2 (COX-2) are vital for wound healing; however, no reports have demonstrated a direct action of ELF-EMF in the modulation of these inflammatory molecules in human keratinocytes.

OBJECTIVES

The present study analysed the effect of ELF-EMF on the human keratinocyte cell line HaCaT in order to assess the mechanisms of action of ELF-EMF and to provide further support for their therapeutic use in wound healing.

METHODS

Exposed HaCaT cells were compared with unexposed control cells. At different exposure times, expression of inducible NOS (iNOS), endothelial NOS (eNOS) and COX-2 was evaluated by Western blot analysis. Modulation of iNOS and eNOS was monitored by evaluation of NOS activities, production of nitric oxide (NO) and O(2)(-) and expression of activator protein 1 (AP-1). In addition, catalase activity and prostaglandin (PG) E(2) production were determined. Effects of ELF-EMF on cell growth and viability were monitored.

RESULTS

The exposure of HaCaT cells to ELF-EMF increased iNOS and eNOS expression levels. These ELF-EMF-dependent increased expression levels were paralled by increased NOS activities, and increased NO production. In addition, higher levels of AP-1 expression as well as a higher cell proliferation rate were associated with ELF-EMF exposure. In contrast, ELF-EMF decreased COX-2 expression, PGE(2) production, catalase activity and O(2)(-) production.

CONCLUSIONS

Mediators of inflammation, such as reactive nitrogen and PGE(2), and keratinocyte proliferation are critical for the tissue regenerative processes. The ability of ELF-EMF to upmodulate NOS activities, thus nitrogen intermediates, as well as cell proliferation, and to downregulate COX-2 expression and the downstream intermediate PGE(2), highlights the potential therapeutic role of ELF-EMF in wound healing processes.

Tumor promoter TPA stimulates MMP-9 secretion from human keratinocytes by activation of superoxide-producing NADPH oxidase

Matrix metalloproteinase-9 (MMP-9) is involved in physiological tissue remodelling processes as well as in tumor invasion and metastasis. The tumor promoter 12-O-tetradecanoylphorbol-13-acetate (TPA) increases MMP-9 secretion from normal human epidermal keratinocytes (NHEK) in vivo and in vitro. Here we show that the flavoprotein inhibitor diphenyleneiodinium (DPI) and the NADPH oxidase inhibitor apocynin block TPA-induced MMP-9 secretion of NHEK in vitro. Furthermore, N-acetyl-L-cysteine and L-cysteine lowered TPA-induced MMP-9 secretion, suggesting an involvement of reactive oxygen species(ROS). TPA exerts its effect on MMP-9 gene expression and secretion via the superoxide-producing enzyme NADPH oxidase: TPA rapidly stimulates generation of superoxide anion as well as gene expression of two cytosolic NADPH oxidase subunits (p47-phox and p67-phox) after 2 h, which is followed by induction of MMP-9 gene expression after 4 h. Taken together, the novel finding herein is the TPA-induced MMP-9 secretion from normal human epidermal keratinocytes through a NADPH oxidase dependent pathway.

Review

Production of superoxide anion O2*- by the membrane-bound enzyme NADPH oxidase of phagocytes is a long-known phenomenon; it is generally assumed that O2*-helps phagocytes kill bacterial intruders. The details and the chemistry of the killing process have, however, remained a mystery. Isoforms of NADPH oxidase exist in membranes of nearly every cell, suggesting that reactive oxygen species (ROS) participate in intra- and intercellular signaling processes. What the nature of the signal is exactly, how it is transmitted, and what structural characteristics a receptor of a "radical message" must have, have not been addressed convincingly. This review discusses how the action of messengers is in agreement with radical-specific behavior. In search for the smallest common denominator of cellular free radical activity we hypothesize that O2*- and its conjugate acid, HO2*, may have evolved under primordial conditions as regulators of membrane mechanics and that isoprostanes, widely used markers of "oxidative stress", may be an adventitious correlate of this biologic activity of O2*-/HO2*. An overall picture is presented that suggests that O2*-/HO2* radicals, by modifying cell membranes, help other agents gain access to the hydrophobic region of phospholipid bilayers and hence contribute to lipid-dependent signaling cascades. With this, O2*-/HO2* are proposed as indispensable adjuvants for the generation of cellular signals, for membrane transport, channel gating and hence, in a global sense, for cell viability and growth. We also suggest that many of the allegedly O2*- dependent bacterial pathologies and carcinogenic derailments are due to membrane-modifying activity rather than other chemical reactions of O2*-/HO2*. A consequence of this picture is the potential evolution of the "radical theory of ageing" to a "lipid theory of aging".

Fibroblast dysfunction is a key factor in the non-healing of chronic venous leg ulcers

Chronic age-related degenerative disorders, including the formation of chronic leg wounds, may occur due to aging of the stromal tissues and ensuing dysfunctional cellular responses. This study investigated the impact of environmental-driven cellular aging on wound healing by conducting a comprehensive analysis of chronic wound fibroblast (CWF) behavior in comparison with patient-matched healthy skin normal fibroblasts (NF). The dysfunctional wound healing abilities of CWF correlated with a significantly reduced proliferative life span and early onset of senescence compared with NF. However, pair-wise comparisons of telomere dynamics between NF and CWF indicated that the induction of senescence in CWF was telomere-independent. Microarray and functional analysis suggested that CWFs have a decreased ability to withstand oxidative stress, which may explain why these cells prematurely senescence. Microarray analysis revealed lower expression levels of several CXC chemokine genes (CXCL-1, -2, -3, -5, -6, -12) in CWF compared with NF (confirmed by ELISA). Functionally, this was related to impaired neutrophil chemotaxis in response to CWF-conditioned medium. Although the persistence of non-healing wounds is, in part, due to prolonged chronic inflammation and bacterial infection, our investigations show that premature fibroblast aging and an inability to correctly express a stromal address code are also implicated in the disease chronicity.

Kinetic Modeling of Nitric-Oxide-Associated Reaction Network

PURPOSE

Nitric oxide and superoxide are the two important free radicals in the biological system. The coexistence of both free radicals in the physiological milieu gives rise to intricate oxidative and nitrosative reactions, which have been implicated in many physiological and/or pathophysiological conditions, such as vasodilatation and inflammation. It is difficult, if not impossible, to study the complexity of the nitric oxide/superoxide system using current experimental approaches. Computational modeling thus offers an alternative way for studying the problem.

METHODS

In this present study, key reaction pathways related to the generation, reaction and scavenging of both nitric oxide and superoxide were integrated into a reaction network. The network dynamics was investigated by numerical simulations to a set of coupled differential equations and by dynamical analysis. Two specific questions pertaining to the reaction kinetics of the reactive chemical species in the nitric oxide/superoxide system were studied: (1) how does the system respond dynamically when the generation rate of nitric oxide and superoxide varies? (2) how would antioxidants such as glutathione modulate the system dynamics?

RESULTS

While changing basal GSH levels does not alter the kinetics of nitric oxide, superoxide, and peroxynitrite, the kinetic profiles of N203, GSNO and GSH are sensitive to the variation of basal GSH levels. The kinetics of the potential nitrosative species, N203, is switch like, which is dependent on the level of GSH.

CONCLUSIONS

The model predicts that concurrent high nitric oxide and superoxide generation--such as in the inflammatory conditions--may result in nonlinear system dynamics, and glutathione may serve as a dynamic switch of N203 mediated nitrosation reaction.

Reactive oxygen species scavenging activity during periodontal mucoperiosteal healing: An experimental study in dogs

Excessive release of reactive oxygen species (ROS) in wounded tissue due to inflammation and ischaemia is a deleterious and destructive phenomenon for the healing process. Hence, scavenging of ROS is one of the essential steps in normal wound repair. In this study, we presented a profile of free radical scavenging enzyme (FRSE) activity of periodontal mucoperiosteal wounds in order to investigate ROS activity during periodontal wound healing. Mucoperiosteal periodontal flaps were elevated in the mandibular buccal region of seven dogs between the first premolar and first molar teeth, creating acute incisional wounds in the inner side of the flaps and they were replaced 30 min after elevation. Gingival samples taken from certain biopsy regions at baseline (before flap elevation), day 3, 12, 21 and 30 were processed for detection of active amounts of superoxide dismutase (SOD), catalase (CAT) and glutathione peroxidase (GPX). All enzyme activities had increased by more than 100% of their baseline levels by day 3. SOD activity decreased gradually from days 3 to 30 and reached a level lower than the baseline value. The increase in CAT activity continued until day 21, and decreased to a level higher than the baseline value by day 30. GPX also decreased from day 3, and reached a level less than its baseline value by day 30. Our results suggest that FRSEs may contribute to the detoxification of ROS during periodontal mucoperiosteal healing. This relationship may be utilized to facilitate soft tissue and/or flap management in periodontal or intra-oral treatments.

Cytolysin-dependent evasion of lysosomal killing

Local host defenses limit proliferation and systemic spread of pathogenic bacteria from sites of mucosal colonization. For pathogens such as streptococci that fail to grow intracellularly, internalization and killing by epithelial cells contribute to the control of bacterial growth and dissemination. Here, we show that group A Streptococcus (GAS), the agent of streptococcal sore throat and invasive soft tissue infections, evades internalization and intracellular killing by pharyngeal epithelial cells. Production of the cholesterol-binding cytotoxin streptolysin O (SLO) prevented internalization of GAS into lysosomes. In striking contrast, GAS rendered defective in production of SLO were internalized directly or rapidly transported into lysosomes, where they were killed by a pH-dependent mechanism. Because SLO is the prototype of cholesterol-dependent cytolysins produced by many Gram-positive bacteria, cytolysin-mediated evasion of lysosomal killing may be a general mechanism to protect such pathogens from clearance by host epithelial cells.

Lipoxygenase-dependent superoxide release in skeletal muscle

Superoxide anion radical (O2•−) is released from skeletal muscle at rest and is particularly elevated during conditions of heat stress (42°C). Previous studies have shown that in isolated rat diaphragm O2•−release is not dependent on mitochondrial electron transport, reduced NADP oxidase activity, or the integrity of membrane anion channels. This study hypothesized that O2•−release, as measured by cytochrome c reduction, is linked to metabolism of arachidonic acid. Phospholipase A2inhibition with manoalide significantly decreased O2•−release. In downstream pathways, neither the blockage of cyclooxygenase with indomethacin nor the inhibition of cytochrome P-450-dependent monooxygenase with SKF-525A decreased O2•−release. However, lipoxygenase (LOX) inhibition with general LOX blockers 5,8,11,14-eicosatetraynoic acid and cinnamyl-3,4-dihydroxy-α-cyanocinnamate greatly attenuated the signal. Furthermore, the specific 5-LOX inhibitor diethylcarbamazine also significantly decreased O2•−release. Immunohistochemistry localized 5- and 12-LOX to the cytosol and sarcolemma of muscle cells. Confocal studies, using the O2•−-sensitive fluorescent indicator hydroethidine, demonstrated that LOX inhibition had no significant influence on intracellular O2•−formation. When compared with the cytochrome c results, this indicates that intra- and extracellular O2•−must arise from different sources. These data show for the first time that arachidonic acid metabolism through LOX activity, is a major source of extracellular O2•−release in skeletal muscle.

A constitutive NADPH oxidase-like system containing gp91phox homologs in human keratinocytes

In non-phagocytic cells, superoxide has been implicated in physiological and pathological cellular functions in the skin and mucosa, such as, host defense, mitogenic responses, and malignant conversion. Here, we identify a constitutively expressed heme-flavoprotein NADPH oxidase (Nox) system as a source of superoxide in human skin (HaCaT) and gingival mucosal (GM16) keratinocyte cell lines. Western blot analysis showed that both cell lines expressed the phagocyte oxidase (phox) cytosolic proteins Rac1, p40phox, and p67phox. With respect to the catalytic flavoheme protein subunit, HaCaT membranes, which expressed p22phox, showed an absorbance peak at 558 nm indicative of a b-type cytochrome. At mRNA levels, both GM16 and HaCaT cells expressed gp91phox homologs Nox1, Nox2, and Nox4, however, HaCaT cells expressed very low levels of Nox1 mRNA. At protein levels, Nox1 was readily detected in HaCaT but was nearly undetectable in GM16 cells. Consistently, Nox activity of HaCaT membranes was demonstrated by electron paramagnetic resonance spin-trapping and cytochrome c reduction, and the activity was sensitive to the flavoprotein inhibitor diphenylene iodonium. V(max) values were 20-fold lower than those reported for phagocytic oxidase. In conclusion, keratinocytes expressed a Nox distinct from the phox isoform of phagocytes providing molecular evidence for a source of superoxide that may regulate cell proliferation and host defense in skin and oral mucosa.

The role of oxidants and antioxidants in psoriasis

BACKGROUND

Psoriasis vulgaris is a chronic inflammatory skin disease characterized by well-demarcated erythema and scaly plaques. The pathogenesis of psoriasis still remains unclear. An increased reactive oxygen species (ROS) and insufficient antioxidant activity have been determined in psoriatic lesions.

AIM OF THE STUDY

To evaluate and compare superoxide dismutase (SOD) and glutathione peroxidase (GP) activity in erythrocytes, catalase (CAT) activityand malondialdehyde (MDA) levels in serum of subjects with psoriasis and controls as well as MDA levels in skin biopsies from both groups.

STUDY POPULATION

Twenty-two psoriatic patients (12 women and ten men) and 22 (12 women and ten men) healthy controls were involved in this study.

FINDINGS

Statistically significant decreased levels of erythrocyte SOD and GP activities were noted in psoriatic subjects. Furthermore, a statistically significant increased serum CAT activity was found in the psoriasis group. No statistically significant difference was found in the serum MDA levels in the two groups, however, statistically significant increased tissue levels of MDA were noted in the psoriasis group.

CONCLUSIONS

Our results support the hypothesis of an imbalance in the oxidant-antioxidant system in psoriasis.

Lactoperoxidase and hydrogen peroxide metabolism in the airway

Hydrogen peroxide (H2O2) is known to play an important role in airway homeostasis. For this reason its levels and thus its synthesis and consumption are important mechanisms for controlling airway functions. We have identified the major macromolecular consumer of H2O2 in sheep airway secretions to be lactoperoxidase (LPO), a heme peroxidase previously studied in milk and saliva. This enzyme uses H2O2 to oxidize the anion thiocyanate to an antibiotic compound that prevents growth of bacteria, fungi, and viruses. LPO was isolated from sheep airways and proved to be a major constituent comprising about 1% of the soluble protein in airway secretions. The isolated airway LPO was catalytically active and displayed the enzymatic characteristics previously described for the enzyme isolated from bovine milk. Airway LPO activity was shown to increase the rate of bacterial clearance from sheep airways. The role of this enzyme in the airway host defense strongly suggests that an active H2O2 production system exists to supply appropriate substrate for the enzyme. The identity of this H2O2 synthesis system is an important, yet unknown feature of airway oxygen radical metabolism.

Aberrant redox regulation in human metastatic melanoma cells compared to normal melanocytes

Melanocytes and melanoma cells contain melanin, a complex polymer that modulates redox changes in these cells. Relative intracellular hydrogen peroxide levels measured by dichlorodihydrofluorescein are similar in the two cell types, but the levels of superoxide anion measured by dihydroethidium were markedly increased in melanoma cells. Chelator-induced oxidative stress is efficiently suppressed by melanocytes without substantial recruitment of the transcription factors NF-kappaB and AP-1 as measured by electrophoretic mobility shift assay and quantitated by densitometry or by a change in frequency of apoptosis as determined by annexin V binding. In contrast, NF-kappaB in melanoma cells is strongly recruited by changes in redox status and exhibits a correlative relationship to intracellular hydrogen peroxide (but not superoxide anion). However, the response of the NF-kappaB pathway to intracellular hydrogen peroxide is anomalous, including downregulation of p65 and IkappaBalpha RNA expression (Northern blot). Additionally, recruitment of AP-1 binding in melanoma cells was directly correlated with intracellular levels of superoxide anion (but not hydrogen peroxide). Neither the degree of NF-kappaB nor AP-1 binding in melanoma cells was related to the frequency of apoptosis. The responsiveness of NF-kappaB and AP-1 recruitment to intracellular levels of hydrogen peroxide and superoxide anion without concomitant control of apoptosis provides a general mechanism by which these cells can escape noxious injury (e.g., chemotherapy). The marked enhancement of apoptosis in melanoma cells by chelators indicates, however, that this alteration can be circumvented and offers a unique therapeutic window to explore.

Resveratrol inhibits the proliferation of normal human keratinocytes in vitro

Resveratrol, a phytoalexin found in grapes and other plants, is a potent antioxidant, anti-inflammatory, and antiproliferative agent that is thought to have chemopreventive properties with respect to carcinogenesis. However, the antiproliferative effects of resveratrol have been described primarily for cultured tumor cells and its effects on the proliferation of normal cells are not clear. We evaluated the viability and proliferation of cultured normal human keratinocytes (KCs) exposed to resveratrol (0.25-100 microM) for different lengths of time (5-72 h) by means of (3)H-thymidine incorporation, direct cell counts, and a tetrazolium-based formazan reaction. The first two methods indicated that resveratrol, even at low concentrations, induced a time-and concentration-dependent inhibition of KC proliferation. However, formazan production was actually increased at moderate resveratrol concentrations (10 microM) and diminished only at higher concentrations. Even brief exposure (5 h) of KCs to resveratrol resulted in a concentration-dependent elevation in formazan production. This was blocked by ionomycin but was not dependent on Ca(2+). We conclude that resveratrol, even at submicromolar concentrations, inhibits the proliferation of normal human KCs in vitro and, at higher concentrations (40-100 microM), is cytotoxic to these cells. J. Cell. Biochem. Suppl. 36: 55-62, 2001.

V-Ha-Ras overexpression induces superoxide production and alters levels of primary antioxidant enzymes

Reactive oxygen species have been shown to play important roles in v-Ha-Ras mitogenic signaling. We hypothesized that v-Ha-Ras overexpression would induce superoxide production, and therefore modify expression of the primary antioxidant enzyme system. We have demonstrated that immortal rat kidney epithelial cells stably transduced with constitutively active v-Ha-ras produced significantly larger amounts of superoxide radical than wild-type or vector-transfected control cells. The levels of the primary antioxidant enzymes copper- and zinc-containing superoxide dismutase, manganese-containing superoxide dismutase, catalase, and glutathione peroxidase were increased in the superoxide-overproducing cells. DNA-binding activities of the transcription factors activator protein-1, activator protein-2, and nuclear factor-kappaB were all enhanced in the superoxide-overproducing cells. These v-Ha-ras transduced cells also had a shortened cell doubling time and higher plating efficiency, and displayed greater constitutive levels of phosphorylated mitogen-activated protein kinases. These data demonstrate that v-Ha-Ras overexpression increases superoxide production and this apparently affects a wide variety of cell signaling and redox systems.

Hypothermia injury/cold-induced apoptosis--evidence of an increase in chelatable iron causing oxidative injury in spite of low O2-/H2O2 formation

When incubated at 4 degrees C, cultured rat hepatocytes or liver endothelial cells exhibit pronounced injury and, during earlier rewarming, marked apoptosis. Both processes are mediated by reactive oxygen species, and marked protective effects of iron chelators as well as the protection provided by various other antioxidants suggest that hydroxyl radicals, formed by classical Fenton chemistry, are involved. However, when we measured the Fenton chemistry educt hydrogen peroxide and its precursor, the superoxide anion radical, formation of both had markedly decreased and steady-state levels of hydrogen peroxide did not alter during cold incubation of either liver endothelial cells or hepatocytes. Similarly, there was no evidence of an increase in O2-/H2O2 release contributing to cold-induced apoptosis occurring on rewarming. In contrast to the release/level of O2- and H2O2, cellular homeostasis of the transition metal iron is likely to play a key role during cold incubation of cultured hepatocytes: the hepatocellular pool of chelatable iron, measured on a single-cell level using laser scanning microscopy and the fluorescent indicator phen green, increased from 3.1 +/- 2.3 microM (before cold incubation) to 7.7 +/- 2.4 microM within 90 min after initiation of cold incubation. This increase in the cellular chelatable iron pool was reversible on rewarming after short periods of cold incubation. The cold-induced increase in the hepatocellular chelatable iron pool was confirmed using the calcein method. These data suggest that free radical-mediated hypothermia injury/cold-induced apoptosis is primarily evoked by alterations in the cellular iron homeostasis/a rapid increase in the cellular chelatable iron pool and not by increased formation of O2-/H2O2.

Superoxide production from paraquat evoked by exogenous NADPH in pulmonary endothelial cells

Superoxide production from paraquat in a pulmonary microvascular endothelial cell (PMEC) suspension was demonstrated using 2-methyl-6-(p-methoxyphenyl)-3,7-dihydroimidazo[1,2-alpha]pyraz in-3-one (MCLA), a chemiluminescence probe, to detect superoxide anions. Increased rates of superoxide production from paraquat, which were sensitive to superoxide dismutase (SOD), required the presence of reduced nicotinamide adenine dinucleotide phosphate (NADPH) in the reaction medium, and occurred instantaneously after the addition of NADPH, which is impermeable to cell membranes. NADH as an electron donor was not as effective, and xanthine or succinate had no influence. Paraquat was anaerobically reduced in the presence of NADPH and PMECs to yield a one-electron reduced radical, and the reduction was inhibited by NADP+. Diphenyleneiodonium, an inhibitor of flavoprotein reductases, also markedly inhibited both paraquat reduction and superoxide production. These results indicate that NADPH-dependent superoxide production from paraquat probably occurs by a flavoprotein with NADPH-dependent reductase activity in cell membranes. NADPH-dependent superoxide production from paraquat was also reproduced using adherent PMECs on wells. Under these conditions, superoxide production was enhanced with agonists, including interleukin-1beta, A23187, and phorbol 12-myristate 13-acetate. The effect of the former two was blocked with staurosporine, while the latter's effect was suppressed with calyculin A.

Roles of reactive oxygen species: signaling and regulation of cellular functions

Reactive oxygen species (ROS) are the side products (H2O2, O2.-, and OH.) of general metabolism and are also produced specifically by the NADPH oxidase system in most cell types. Cells have a very efficient antioxidant defense to counteract the toxic effect of ROS. The physiological significance of ROS is that ROS at low concentrations are able to mediate cellular functions through the same steps of intracellular signaling, which are activated by natural stimuli. Moreover, a variety of natural stimuli act through the intracellular formation of ROS that change the intracellular redox state (oxidation-reduction). Thus, the redox state is a part of intracellular signaling. As such, ROS are now considered signal molecules at nontoxic concentrations. Progress has been achieved in studying the oxidative activation of gene transcription in animal cells and bacteria. Changes in the redox state of intracellular thiols are considered to be an important mechanism that regulates cell functions.

Superoxide radical production by sponges Sycon sp

Using the catechol Tiron as an O2-. scavenger, we showed that sea sponges (Sycon sp.) produce superoxide radicals in sea water at a high rate without any stimuli added. The rate of O2-. outflow from sponges to their water surroundings reaches a value of 0.5 nmol/min per sponge at pH 6.5. The generation of O2-. was inhibited by Cu,Zn-superoxide dismutase, and restored by the addition of KCN. We also confirmed the abiotic production of O2-. in sea water, detected earlier with a different method by Petasne and Zika [Nature 325 (1987) 516-518].