A comparative study of oxidant–antioxidant status in stable and active vitiligo patients

The pathogenetic mechanisms in vitiligo have not been completely clarified. One of the major hypotheses in the pathogenesis of vitiligo is the oxidative stress hypothesis. The active or stable phase of vitiligo is defined on the basis of the progression or appearance of new lesions in the last 3 months and the absence of new lesions or their progression in the last 6 months, respectively. Eighteen patients with active vitiligo, 18 patients with stable vitiligo, and 40 controls were included in this study. We examined serum levels of malondialdehyde, selenium, vitamin E and A, and the erythrocyte activities of glutathione peroxidase, superoxide dismutase, and catalase. Our results revealed a significantly higher level of serum malondialdehyde, selenium in patients with active disease compared with the controls. Significant higher increase in erythrocytes superoxide dismutase activities was observed in active vitiligo group, erythrocyte glutathione peroxidase activity was decreased significantly in active disease, whereas erythrocyte catalase activity and plasma vitamin E and A levels were not different in vitiligo patients as compared with controls. Our study shows that oxidative stress is involved in the pathophysiology of both active and stable vitiligo but increased imbalance of antioxidants was observed in the blood of active vitiligo patients.I dedicate this article to our dear director (Mme Hentati Basma) who dead in 06/06/06. We will never forget you and you are always in our heart.     

The role of oxidants and antioxidants in generalized vitiligo

Oxidative stress may be induced by increasing the generation of reactive oxygen species (ROS) and other free radicals. The generation of ROS is known to be associated with a decrease in antioxidant levels. In the present study, the role of oxidative stress was assessed in the pathogenesis of generalized vitiligo. Superoxide dismutase (SOD), glutathione peroxidase (GSH-Px), and glutathione (GSH) levels in erythrocytes and serum malondialdehyde (MDA) and nitric oxide (NO) levels were investigated in 24 patients with generalized vitiligo and 20 healthy controls. Our results indicated that significantly increased levels of erythrocyte SOD, serum MDA, and NO were associated with a marked reduction of erythrocyte GSH-Px and GSH activities in patients with generalized vitiligo (p<0.05). Our observations suggest that the presence of an imbalance in the oxidant-antioxidant system might play a role in the pathogenesis of vitiligo. Our results further support the concept that free radical-mediated damage may be the initial pathogenic event in melanocyte degeneration in generalized vitiligo.     

白癜风患者血清及皮损中某些酶及微量元素改变研究

本研究检测白癜风患者血清中超氧化物岐化酶(SOD)、谷胱甘肽过氧化物酶(GSH-Px)、黄嘌呤氧化酶(XOD)活性,丙二醛(MDA)水平及血清、皮肤中锌(Zn)、铜(Cu)、硒(Se)、铁(Fe)含量。结果表明:患者血清中GSH-Px、SOD活性及Cu含量低于对照组(P<0.01),MDA、Fe含量高于对照组(P<0.01).皮损处Zn、Cu、Se或Fe含量分别低于或高于周围外观正常皮肤,治疗后血清SOD、GSH-Px活性增高、Cu、Fe含量显著降低(P<0.01)。提示:白癜风患者自由基防御系统中部分酶活性降低,Zn、Cu、Se缺乏。     

白癜风患者皮肤组织液氧化-抗氧化物水平比较分析

目的探讨体内氧化-抗氧化状态与白癜风发病的关系。方法采用化学比色法,对24例白癜风患者白斑和非白斑(正常部位皮肤)以及10例健康者组织液进行过氧化氢(H2O2)、过氧化氢酶(CAT)和谷胱甘肽过氧化物酶(GSH-PX)检测。结果白癜风患者白斑H2O2水平(53.97±19.03)mmol/L明显高于健康组(28.98±22.81)mmol/L,进展期患者白斑H2O2水平(56.64±19.91)mmol/L明显高于非白斑(34.71±22.23)mmol/L,差异均有统计学意义(P均﹤0.01);白癜风白斑CAT水平(17.34±11.05)U/mL明显低于健康组(41.29±16.57)U/mL,差异有统计学意义(P﹤0.01),进展期白斑CAT水平(13.63±8.32)U/mL低于非白斑(35.72±16.14)U/mL,差异有统计学意义(P﹤0.05);进展期患者的白斑与非白斑处GSH-PX均高于健康组,差异有统计学意义(P均﹤0.05)。结论白癜风发病可能与H2O2增高、CAT降低等氧化-抗氧化失衡有关。     

Circulatory levels of antioxidants and lipid peroxidation in Indian patients with generalized and localized vitiligo

Vitiligo is an acquired skin disease, characterized by white areas on the skin due to loss of functional melanocytes. The pathogenesis of the disease is still unclear. Published data show the involvement of oxidative stress in the pathophysiology of vitiligo. A total of 30 vitiligo patients and 30 healthy controls were included in this study. We estimated serum levels of malondialdehyde (MDA), vitamins E and C, total antioxidant activity and whole blood levels of superoxide dismutase (SOD) and glutathione peroxidase (GPx) in vitiligo patients and controls. We found significantly higher levels of MDA and significantly lower levels of SOD, GPx, vitamins C and E and total antioxidant activity in vitiligo patients compared with controls. This study is a maiden attempt to report on antioxidant parameters of both generalized/localized-type Indian vitiligo patients. Our results confirmed that oxidative stress may play an important role in the pathogenesis of vitiligo and cause melanocyte damage in vitiligo.     

Perturbed 6-tetrahydrobiopterin recycling via decreased dihydropteridine reductase in vitiligo: more evidence for H2O2 stress

To date there is ample evidence that patients with vitiligo accumulate millimolar concentrations of hydrogen peroxide (H2O2) in their epidermis as well as in their blood lymphocytes/monocytes. Several enzymes are affected by this H2O2 including catalase, glutathione peroxidase, and 4 alpha-carbinolamine dehydratase. The latter enzyme disrupts the recycling of the essential cofactor (6R)-L-erythro-5,6,7,8-tetrahydrobiopterin (6BH4) for the aromatic amino acid hydroxylases as well as the nitric oxide synthases. In this report we have elucidated the influence of H2O2 on dihydropteridine reductase (DHPR), the last enzyme in the 6BH4-recycling process. Here we show for the first time that concentrations of less than 30 microM H2O2 increase DHPR activities, whereas levels greater than 30 microM H2O2 deactivate the enzyme based on the oxidation of Met146 and Met151 in the sequence, consequently leading to disruption of the NADH-dependent enzyme active site. This oxidation was confirmed by Fourier transform-Raman spectroscopy yielding the expected SO band at 1025 cm-1 characteristic of methionine sulfoxide. Hence these results unmasked a novel regulatory mechanism for DHPR enzyme activity. Moreover, we also demonstrated that DHPR activities in whole blood of patients with vitiligo are significantly decreased in untreated patients, whereas activities are normalized after removal of epidermal H2O2 with a topical pseudocatalase (PC-KUS). Taken together, these new data add more evidence to a systemic involvement of H2O2 in the pathomechanism of vitiligo.     

Antioxidant enzymes and lipid peroxidation at the tissue level in patients with stable and active vitiligo

Background  The pathogenetic mechanisms in vitiligo have not been clarified completely. One of the major hypotheses in the pathogenesis of vitiligo is the oxidative stress hypothesis. The active and stable phases of vitiligo are defined as the progression or appearance of new lesions in the last 3 months and the absence of new lesions or progression in the last 6 months, respectively.
Methods  We examined the levels of malondialdehyde, catalase, glutathione peroxidase, and superoxide dismutase in the tissues of 10 patients with active vitiligo, 10 patients with stable vitiligo, and 20 matched healthy controls.
Results  The results revealed that the levels of superoxide dismutase, glutathione peroxidase, and malondialdehyde in tissues were increased significantly in patients with active vitiligo relative to those in patients with stable vitiligo and matched controls; however, the levels of catalase in tissues were decreased significantly in patients with active vitiligo relative to those in patients with stable vitiligo and matched controls.
Conclusions  Our study shows that oxidative stress is involved in the pathophysiology of both active and stable vitiligo, but an increased imbalance of antioxidants is observed in the tissues of patients with active vitiligo.     

Increase in total blood antioxidant status and selenium levels in black patients with active vitiligo

BACKGROUND: Oxidative stress could be an important phenomenon leading to melanocyte death in vitiligo. The accumulation of hydrogen peroxide (H2O2) and low catalase levels have recently been demonstrated in the epidermis of vitiligo patients. Few abnormalities of antioxidants have been found in the blood of patients with vitiligo, except for an elevation of selenium. No studies on oxidative stress have been performed so far on patients with skin phototype VI (Fitzpatrick classification). AIM: To study the blood antioxidant status of black patients with active generalized vitiligo. METHODS: Randox total antioxidant status, selenium, ferritin, transferrin, ceruloplasmin, tocopherol, and retinol levels were evaluated in blood samples obtained from 11 dark-skinned patients from the French West Indies (Isle of Martinique) with recent active lesions of vitiligo and from 11 age- and sex-matched healthy volunteers. RESULTS: Total blood antioxidant status and selenium levels were significantly increased in vitiligo patients, compared to those in sex- and age-matched controls (P < 0.01 and P < 0.02, respectively). Blood levels of ferritin, transferrin, ceruloplasmin, retinol, and tocopherol were not significantly modified. CONCLUSIONS: This is the first report on the global blood antioxidant status in vitiligo. The increase in total blood antioxidant status observed in black patients was an unexpected result that needs to be confirmed and explained by further studies. The spontaneous increase in selenium levels could be of interest, as it has been recommended in the treatment of vitiligo.     

白癜风患者血清过氧化氢、过氧化氢酶和谷胱甘肽过氧化物酶的检测

目的探讨体内氧化物和抗氧化物与白癜风发病的关系。方法分别检测40例白癜风患者和10例健康对照者的血清过氧化氢(H2O2)、过氧化氢酶(CAT)和谷胱甘肽过氧化物酶(GSH-PX)。结果白癜风患者CAT浓度(9.31±6.52)U/mL明显低于对照组(33.05±9.47)U/mL,其进展期CAT浓度(7.3±6.01)U/mL明显低于稳定期(13.05±6.11)U/mL,差异均有统计学意义(P均<0.01);而白癜风患者H2O2和GSH-PX水平与对照组比较,差异无统计学意义(P>0.05)。结论白癜风的发生可能与血清氧化物—抗氧化物水平的变化有一定的相关性。     

COMPARISON OF PLASMA MALONDIALDEHYDE, GLUTATHIONE, GLUTATHIONE PEROXIDASE, HYDROXYPROLINE AND SELENIUM LEVELS IN PATIENTS WITH VITILIGO AND HEALTHY CONTROLS

Background:

The etiology and pathophysiologic mechanism of vitiligo are still unclear. The relationship between increased oxidative stress due to the accumulation of radicals and reactive oxygen species and the associated changes in blood and epidermal component of vitiliginous skin have been reported many times. We investigated the possible changes of plasma malondialdehyde, glutathione, selenium, hydroxyproline and glutathione peroxidase activity levels in patients with vitiligo in order to evaluate the relationship between oxidative stress and etiopathogenesis of vitiligo.

Materials and Methods:

Plasma malondialdehyde, glutathione, hydroxyproline and glutathione peroxidase activity levels were measured by spectrophotometric methods, and HPLC was used for measurement of selenium concentrations.

Results:

Our results showed increased malondialdehyde, hydroxyproline and glutathione peroxidase activity levels in plasma of vitiligo group (P < 0.05).

Conclusion:

Support of antioxidant system via nonenzymatic antioxidant compounds and antioxidant enzymes may be useful to prevent of melanocyte degeneration which occur due to oxidative damage in vitiligo.     

The role of oxidants and antioxidants in generalized vitiligo at tissue level

BACKGROUND: The role of oxidative stress has not been fully understood in the aetiopathogenesis of vitiligo in different studies. AIM: We aimed to investigate the role of the oxidative stress in the pathogenesis of vitiligo. METHODS: In this study, we examined levels of superoxide dismutase, glutathione peroxidase, malondialdehyde and nitric oxide in tissue of 25 patients with generalized vitiligo and 25 healthy controls. RESULTS: Our results revealed that levels of superoxide dismutase, glutathione peroxidase and malondialdehyde in tissue were significantly increased in patients with generalized vitiligo (P < 0.05). However, there was no statistically significantly difference between two groups at tissue level of nitric oxide (P > 0.05). CONCLUSION: Our results demonstrate the presence of an imbalance in the oxidant-antioxidant system in vitiligo at tissue level and provide further support for a free radical-mediated damage as an initial pathogenic event in melanocyte degeneration in vitiligo.     

A comparative study of superoxide dismutase, catalase, and glutathione peroxidase activities and nitrate levels in vitiligo patients

BACKGROUND: Several groups have shown the involvement of oxidative stress in the pathophysiology of vitiligo. METHODS: In this study, we examined the erythrocyte and plasma activities of glutathione peroxidase and Cu/Zn superoxide dismutase, plasma nitrite/nitrate levels, and erythrocyte catalase activity in 23 vitiligo patients and 25 controls. RESULTS: The results show that erythrocyte superoxide dismutase activity and plasma nitrite/nitrate levels are high in vitiligo patients. CONCLUSIONS: Our study confirms that oxidative stress is involved in the pathophysiology of vitiligo, as indicated by the high levels of erythrocyte superoxide dismutase activity and plasma nitrite/nitrate.     

白癜风患者血浆中氧化与抗氧化相关指标的检测

目的通过对白癜风患者及健康对照者血浆中氧化与抗氧化相关指标——超氧化物歧化酶(SOD)、过氧化氢酶(CAT)、谷胱甘肽过氧化物酶(GSH-Px)、丙二醛(MDA)、维生素E(VitE)及一氧化氮(NO)表达水平的测定,探讨氧化应激在白癜风发病机制及疾病发展中的作用和意义。方法选择60例白癜风患者(患者组)和40名健康志愿者(健康对照组)为研究对象,化学法检测血浆中SOD,CAT,GSH-Px的活性及MDA,VE和NO的含量。结果患者组血浆中MDA含量及SOD活性明显高于健康对照组(P<0.01),而GSH-Px活性明显低于健康对照组(P<0.01);进展期白癜风患者血浆中MDA的含量及SOD的活性明显高于稳定期白癜风组(P<0.01),而GSH-Px活性明显低于稳定期白癜风患者(P<0.01);随MDA含量增加,GSH-Px活性逐渐降低,呈显著负相关关系(r=-0.337,P<0.01),而SOD活性逐渐升高,呈显著正相关关系(r=0.347,P<0.01);而在进展期和稳定期白癜风患者血浆中CAT,VE和NO的含量与健康对照组相比差异无统计学意义(P>0.05)。结论白癜风患者血浆中存在氧化-抗氧化失衡,白癜风的发病及病情活动与氧化应激可能相关。     

Oxidant-antioxidant enzymes and lipid peroxidation in generalized vitiligo

Vitiligo is a common pigmentary disorder of the skin with selective destruction of melanocytes. The pathogenetic mechanisms in vitiligo have not been completely clarified. The aim of our investigation was to evaluate the oxidative stress in the pathogenesis of generalized vitiligo. Twenty-seven patients with generalized vitiligo and 24 phototype-, age-, and sex-matched healthy controls were included in this study. We analysed serum levels of malondialdehyde (MDA), nitric oxide (NO), and serum activities of superoxide dismutase (SOD) and xanthine oxidase (XO) in the patients with vitiligo and in the controls. We found significantly higher levels of MDA and XO activity (P < 0.001 and P < 0.05, respectively), and a significantly lower level of serum SOD activity (P < 0.05) in patients with vitiligo compared with the controls. However, the increase in the level of serum NO was insignificant (P > 0.05). These results suggest that lipid peroxidation of cellular membrane of melanocytes by free radicals may have a significant role in the pathogenesis of generalized vitiligo.     

Uric Acid: a new antioxidant in patients with pemphigus vulgaris

Background:

Increased reactive oxygen species (ROS) and lipid peroxidation are seen in many dermatologic disorders, for example, atopic dermatitis, psoriasis, vitiligo, acne vulgaris, pemphigus vulgaris (PV), lichen planus, and alopecia areata. ROS has an important role in the inflammation process. In PV, increased production of ROS leads to decline of antioxidants in plasma and red blood cells which results in oxidative stress. We aimed to evaluate the level of these antioxidants in PV patients and compare it to the controls.

Materials and Methods:

Among patients attending the dermatology clinics, 30 patients with PV, who had never been on treatment, were enrolled to the study. The control group consisted of 30 age- and sex-matched healthy non-smoker individuals. Venous blood was collected from the subjects for the evaluation of plasma levels of glutathione peroxidase, vitamin C, selenium, bilirubin, and uric acid.

Results:

Age mean and standard deviation of the patients (40.83, 12.74) was comparable to the controls (41.96, 13.08). Mean level of uric acid was significantly lower in PV patients compared to the controls (P = 0.006). Other antioxidants were not different between the two groups. Uric acid of the patients with mucosal involvement was significantly lower than patients with mucocutaneous involvement (P = 0.049).

Limitations:

The blood level of other antioxidants (e.g. malondialdehyde) was not evaluated.

Conclusions:

Uric acid as an antioxidant in our study had similar changes to previous studies in the field of other diseases but selenium, bilirubin, and glutathione peroxidase did not differ between patients and controls.     

Relationship between Levels of Soluble Interleukin-2 Receptors and the Types and Activity of Vitiligo

Levels of serum-soluble interleukin-2 receptors (serum sIL-2R) are thought to indicate the activation of immunocompetent cells, mainly lymphocytes. Elevated levels of serum sIL-2R have been observed in various infectious and autoimmune diseases and also after organ transplantation. It has been hypothesized that autoimmune mechanisms are involved in the pathogenesis of vitiligo. Therefore, we studied serum sIL-2R levels in relation to disease types and activity of vitiligo. We used sera separated from venous blood samples from 12 patients with dermatomally distributed type B vitiligo, 17 patients with non-dermatomally distributed type A vitiligo during the active stage, 9 patients with type A vitiligo during the inactive stage, and 12 normal control subjects. Serum sIL-2R levels were similar in type B vitiligo patients and the controls but were significantly elevated in patients with active type A vitiligo compared with controls and inactive type A vitiligo patients. It is suggested that the immune system is activated in patients with type A vitiligo during the active stage and that autoimmune mechanisms may play a role only in type A vitiligo.     

STUDY OF TOTAL ANTIOXIDANT STATUS AND GLUTATHIONE PEROXIDASE ACTIVITY IN TUNISIAN VITILIGO PATIENTS

Background:

Vitiligo affects one to two percent of the word population. Its pathogenesis has not been clarified yet. Multiple mechanisms such as autoimmune, neuronal, endocrine and oxidative stress resulting from unbalanced antioxidant defense system have been proposed.

Aims:

Our purpose was to study the total antioxidant status and glutathione peroxidase activity in Tunisian vitiligo patients with or without diabetes or dysthyroidism.

Materials and Methods:

We studied 60 vitiligo patients and 62 healthy controls. The sex ratio male/female in vitiligo patients was (27/33 = 0.81). Patients with vitiligo were divided into three groups, according to the association with diabetes or dysthyroidism. The total antioxidant status (TAS), glutathione peroxidase activity (GPX activity) was evaluated by adaptable methods using Kits.

Results and Conclusion:

The generalized vitiligo was the most frequent type (35 patients versus 25 of focal ones). All patients having vitiligo showed low levels of TAS: 0.85 ± 0.7 and low GPX activity: 45 ± 0.6, as compared to the control group: 1.40 ± 0.12 mmol/L; 49 ± 1.8 U/L, (p < 0.01), for TAS and GPX, respectively. The association of low TAS and GPX activities was more pronounced in diabetic vitiligo patients than in dysthyroid vitiligo patients. This study demonstrated that antioxidant processes depletion (low TAS and low GPX activity) is clearly involved with vitiligo in Tunisian patients, regardless of the association of the disease with diabetes or dysthyroidism.     

Methionine sulfoxide reductases A and B are deactivated by hydrogen peroxide (H2O2) in the epidermis of patients with vitiligo

Patients with the depigmentation disorder vitiligo have low catalase expression/activities and constantly accumulate 10(-3) M hydrogen peroxide (H(2)O(2)) in their skin. Such high concentrations of H(2)O(2) oxidize L-methionine residues in proteins and peptides to (R and S)-methionine sulfoxide diasteriomers. In vivo FT-Raman Spectroscopy revealed the presence of methionine sulfoxide in the depigmented skin of patients with active vitiligo. In normal healthy human skin, methionine sulfoxide reductases A and B specifically reduce methionine sulfoxides (S) and (R), respectively, back to L-methionine consequently repairing oxidatively damaged proteins and peptides. In this report, we show that the expression/activities of MSRA and MSRB are significantly decreased in the epidermis of patients with vitiligo compared to healthy controls. Also, we used recombinant human MSRA and MSRB1 to show that both enzymes are deactivated by 10(-3) M H(2)O(2) by 85 and 40%, respectively. Structural modelling based on the crystal structure of human MSRA revealed that the active site of this enzyme is significantly altered after H(2)O(2)-mediated oxidation of L-methionine, L-tryptophan, and L-cysteine residues in its active site. Taken together, our results confirm that very important anti-oxidant enzymes are seriously affected in acute vitiligo.     

白癜风患者血清和皮肤组织液IL-18及IFN-γ水平变化的研究

目的　探讨IL 18和IFN γ在不同类型、不同时期白癜风患者血清及皮肤组织液中水平的变化 ,并分析它们的相关性。方法　采用双抗体夹心ELISA法测定 5 7例不同类型、不同时期白癜风患者血清中IL 18和IFN γ的水平 ,并与 2 0例正常对照组比较 ;对其中 45例患者白斑区、非白斑区及 10例正常对照组皮肤组织液同样进行上述细胞因子检测。结果　寻常型白癜风患者血清IL 18和IFN γ(10 0 .41± 40 .0 6pg/ml ,5 5 .0 2± 6.2 8pg/ml)水平均明显高于 (P均 <0 .0 1)正常对照组 (69.15± 18.68pg/ml ,5 1.19± 6.3 5 pg/ml )。寻常型白癜风患者血清IL 18和IFN γ水平进展期高于稳定期 ,二者呈正相关性 ;散发型白癜风白斑区皮肤组织液IL 18(114 .5 4± 2 8.77pg/ml)水平明显高于 (P <0 .0 1)正常对照组 (65 .0 2± 16.3 5 pg/ml)。节段型白癜风患者血清及皮肤组织液中两种细胞因子水平和对照组差异无显著性 (P>0 .0 5 )。结论　寻常型白癜风患者血清或皮肤组织液中两种细胞因子有异常表达 ;血清中IL 18与IFN γ存在高度相关性 ,表明IL -18及IFN -γ可能参与寻常型白癜风的发病。     

Estrogens can contribute to hydrogen peroxide generation and quinone-mediated DNA damage in peripheral blood lymphocytes from patients with vitiligo

To date there is ample in vivo and in vitro evidence for increased epidermal and systemic hydrogen peroxide (H(2)O(2)) levels in vitiligo, which can be reduced with a topical application of a pseudocatalase-K.U. Schallreuter (PC-KUS) leading to the recovery of epidermal catalase levels as well as other enzymes in peripheral blood cells. Recently, the generation of H(2)O(2) by oxidative metabolism of estrogens and other aromatic steroids was documented. Therefore, it was tempting to follow estrogen-generated H(2)O(2) and its possible effect on DNA damage in peripheral blood lymphocytes from patients with vitiligo before and after the reduction of epidermal H(2)O(2) with pseudocatalase PC-KUS compared to controls. For this purpose, 20 Caucasian patients were grouped in treated responders (group A, n=11) and untreated active/acute disease (group B, n=9) and compared to Caucasian healthy controls (group C, n=7). Consequently, epidermal catalase protein expression in full skin biopsies was assessed using immunofluorescence labelling together with determination of basal H(2)O(2) levels in peripheral blood lymphocytes. To test the influence of estrogen on H(2)O(2) generation and DNA damage, freshly prepared peripheral blood lymphocytes from all three groups were used for the alkaline comet assay in the presence and absence of catalase. The results of this study demonstrated that reduction of epidermal H(2)O(2) leads to both increased epidermal catalase protein expression as well as decreased H(2)O(2) concentrations in lymphocytes. Moreover, a direct estrogen-mediated DNA damage was identified in both patient groups, which was absent in healthy controls. This effect was not abolished by catalase pointing to direct quinone-mediated DNA damage by estrogens in peripheral blood lymphocytes in vitiligo.