Study of total antioxidant status and glutathione peroxidase activity in Tunisian vitiligo patients

The effect of antioxidant dietary supplements and diet-derived circulating antioxidants on vitiligo outcome: evidence from genetic association and comprehensive Mendelian randomization

Background

Previous studies have indicated that antioxidant diets may have a positive impact on vitiligo by interfering with oxidative stress mechanisms. However, there has been a lack of research utilizing the Mendelian randomization (MR) method to analyze the relationship between antioxidant diet intake and vitiligo.

Methods

In this study, we employed both univariate Mendelian randomization (UVMR) and multivariate Mendelian randomization (MVMR) approaches. The specific antioxidant dietary supplements (such as coffee intake, green tea intake, herbal tea intake, standard tea intake, and average weekly red wine intake) as well as diet-derived circulating antioxidants, including Vit. C (ascorbate), Vit. E (α-tocopherol), Vit. E (γ-tocopherol), Carotene, Vit. A (retinol), Zinc, and Selenium (N = 2,603-428,860) were significantly associated with independent single-nucleotide polymorphisms (SNPs). We obtained pooled statistics on vitiligo from a meta-analysis of three genome-wide association studies (GWASs) of European ancestry, including 4,680 cases and 39,586 controls. Inverse variance weighted (IVW) was employed as the primary analytical method, and sensitivity analysis was conducted to assess the robustness of the main findings.

Results

Genetically, coffee intake [odds ratio (OR) = 0.17, 95% confidence interval (CI) 0.07-0.37, p = 1.57 × 10-5], average weekly red wine intake (OR = 0.28, 95% CI 0.08-1.00, p = 0.049), and standard tea intake (OR = 0.99, 95% CI 0.98-0.99, p = 5.66 × 10-7) were identified as protective factors against vitiligo. However, no causal effect between the intake of other antioxidant diets and vitiligo was found. Moreover, no instances of pleiotropy or heterogeneity were observed in this study.

Conclusion

Our study indicates that coffee, standard tea, and red wine consumption can potentially reduce the risk of vitiligo. However, there is insufficient evidence to support that other antioxidant diets have a significant effect on vitiligo.

Assessment of Oxidative/Nitrosative Stress and Raftlin in Vitiligo

Background

Vitiligo is a chronic skin disease characterized by white macules on the skin due to loss of melanocytes. Although there are many theories about the etiopathogenesis of the disease, oxidative stress is identified as an important determinant in the etiology of vitiligo. In recent years, Raftlin has been shown to play a role in many inflammatory diseases.

Aims

The aim of this study was to compare the patients with vitiligo and the control group to determine both oxidative/nitrosative stress markers and Raftlin levels.

Materials and Methods

This study was designed prospectively between September 2017 and April 2018. Twenty-two patients diagnosed with vitiligo and 15 healthy people as the control group were included in the study. Blood samples collected to determine oxidative/nitrosative stress, the antioxidant enzyme, and Raftlin levels were sent to the biochemistry laboratory.

Results

In patients with vitiligo, the activities of catalase, superoxide dismutase, glutathione peroxidase, and glutathione S transferase were significantly lower than in the control group (P < 0.0001). In vitiligo patients, the levels of malondialdehyde, nitric oxide, nitrotyrosine (3-NTx), and Raftlin were significantly higher than in the control group (P < 0.0001).

Conclusions

The results of the study support that oxidative stress and nitrosative stress may play a role in the pathogenesis of vitiligo. In addition, the Raftlin level, a new biomarker of inflammatory diseases, was found high in patients with vitiligo.

Tissue expression of glutathione S transferase isoenzymes in vitiligo

The association of glutathione S-transferase (GST) enzymes with vitiligo is inconclusive. To evaluate tissue expressions of GST isoenzymes in vitiligo patients and to compare these expressions with healthy controls, we used 26 active depigmented patches on the trunk of vitiligo patients and 20 healthy sex and age matched controls. Punch biopsies were taken from the lesioned or normal skin. Tissue expression of GST isoenzymes were analyzed immunohistochemically. Tissue expression of GSTT1, GSTA1 and GSTP1 was significantly higher in the patient group than controls. Tissue expression of GSTM1 was not significantly different between the two groups. The increased tissue expression of GSTT1, GSTA1 and GSTP1 may represent a response to excess free radical formation in vitiligo and may support the role of oxidative stress in the pathogenesis of vitiligo.

Glutathione Peroxidase Level in Patients with Vitiligo: A Meta-Analysis

Abnormality of glutathione peroxidase (GPx) is involved in the etiology and pathogenesis of vitiligo. However, the results were controversial. Aim. The purpose of this meta-analysis is to compare the levels of GPx between vitiligo patients and healthy controls. Methods. Relevant published articles were searched according to eligibility criteria. A meta-analysis was conducted to pool estimates of the standardized mean difference (SMD) with 95% confidence interval (CI). Results. Twenty-three studies with a total of 1076 vitiligo patients and 770 healthy controls were included. The pooled meta-analysis showed that patients with vitiligo had equivalent levels of GPx with the healthy controls (SMD = −0.47, 95% CI: −1.03 to 0.08, and p = 0.095). Further subgroup analysis showed that the GPx levels of Asian patients or segmental vitiligo patients were, respectively, lower than those of healthy controls (Asian: SMD = −0.47, 95% CI: −1.08 to 0.14, and p = 0.001; segmental: SMD = −3.59, 95% CI: −6.38 to −0.80, and p = 0.012). Furthermore, the GPx levels in serum/plasma were significantly decreased in either stable or active vitiligo patients, comparing to healthy controls (stable: SMD = −2.01, 95% CI: −3.52 to −0.49, and p = 0.009; active: SMD = −2.34, 95% CI: −4.07 to −0.61, and p = 0.008). Conclusion. This meta-analysis showed a significant association between low GPx level and vitiligo.

Serum Homocysteine and Total Antioxidant Status in Vitiligo: A Case Control Study in Indian Population

BACKGROUND

Oxidative stress is considered as an initial pathogenic event in melanocyte destruction. These free radicals are scavenged by antioxidants, whose sum of activity in serum is measured by total antioxidant status (TAS). In addition, homocysteine (Hcy) may mediate melanocyte destruction via increased oxidative damage. However, previous studies investigating these parameters in vitiligo provide equivocal results.

AIMS

To study and compare serum Hcy and TAS levels in vitiligo patients with controls and also to correlate these parameters with the various disease characteristics. The present study further looked into any correlation between serum Hcy and TAS in vitiligo.

MATERIALS AND METHODS

A case control study was conducted on 82 vitiligo patients and 83 controls aged 18-45 years after excluding factors which could potentially alter serum Hcy or TAS levels. Disease characteristics were studied and blood samples were obtained for measuring serum Hcy and TAS levels.

RESULTS

TAS levels were lower in vitiligo patients than controls (1.79 ± 0.51 vs. 2.16 ± 0.63 mmol/L; P < 0.001) and had a negative correlation with disease activity (r = -0.410, P < 0.001). However, serum Hcy levels were comparable between vitiligo patients (18.68 ± 9.90 μmol/L) and controls (20.21 ± 13.39 μmol/L) (P = 0.406). No significant correlation was found between serum Hcy and serum TAS levels.

CONCLUSIONS

Serum TAS may be further investigated to establish its role as biomarker for vitiligo since its levels also correlate with disease activity. However, serum Hcy may not be a reliable marker in Indian population probably because of differences in dietary habits.

Evaluation of the Efficacy of Topical Ethyl Vanillate in Enhancing the Effect of Narrow Band Ultraviolet B against Vitiligo: A Double Blind Randomized, Placebo-Controlled Clinical Trial

BACKGROUND

Vitiligo is an acquired disease of skin that presents with depigmented patches due to lack of melanocytes in the epidermis. Accumulation of toxic free radicals like hydrogen peroxide in the epidermis may be responsible for melanocytes death. Since ethyl vanillate (vanillic acid ethyl ester) is a strong hydrogen peroxide scavenger, it may be effective against vitiligo. This study was carried out to evaluate the effect of ethyl vanillate cream on vitiligo patients receiving phototherapy.

METHODS

A double-blind placebo-controlled clinical trial using ethyl vanillate cream 20% was performed on 30 cases of generalized stable vitiligo (randomly selected) who were receiving phototherapy in the outpatient clinic of Faghihi Hospital (Shiraz, Iran). The patients randomly applied ethyl vanillate on an assigned lesion (left or right side of the body) and placebo on the opposite side lesion (almost the same size and location) twice a day for 3 months, while receiving a narrow band ultraviolet B (NB-UVB) 2-3 times weekly. Photos were taken at the beginning of the trial and at the end of 4(th), 8(th), and 12(th) weeks. Then, images were compared with the photos from the beginning of the trial based on VASI score.

RESULTS

There was a significant change in pigmentation after applying ethyl vanillate compared with baseline in medication side (P=0.002), but no significant change in placebo side (P=0.066). Additionally, there was a significant difference between medication and placebo sides in pigmentation (P=0.005).

CONCLUSION

Ethyl vanillate may serve as an adjunct therapy for the treatment of vitiligo, although changes in pigmentation are mild clinically.

Prolidase activity in chronic plaque psoriasis patients

INTRODUCTION

Psoriasis is a chronic, inflammatory, T-cell-mediated and hyperproliferative skin disease characterized by erythematous, squamous, sharply circumscribed and infiltrated plaques. The metabolisms of the collagen proteins undergo considerable changes due to the acceleration of their turnovers as a result of increased prolidase activity in psoriasis patients.

AIM

To determine the level of prolidase activity in psoriasis patients and evaluate its relationship with the oxidative system.

MATERIAL AND METHODS

The serum prolidase enzyme activity, total antioxidant levels and total oxidant levels of 40 psoriasis patients and a control group including 47 healthy individuals were analyzed by using their serum samples, and their oxidative stress indices were calculated.

RESULTS

The prolidase levels (p < 0.01), total oxidant levels (p < 0.01) and oxidative stress index levels (p < 0.001) of the patient group were higher than the corresponding parameters in the control group. The total antioxidant level was low (p < 0.01). Although a positive correlation was found between the prolidase and total antioxidant levels and the total oxidant level, no correlation was found between prolidase and the oxidative stress index.

CONCLUSIONS

It has been determined that the activity of the prolidase enzyme increases due to the increased collage turnover in psoriasis patients. Increased serum oxidant levels and oxidative stress indices values may play a role in the pathogenesis of psoriasis.

Low Glutathione Peroxidase Activity Levels in Patients with Vitiligo

Background

Vitiligo is an idiopathic skin disease characterized by white areas on the skin due to loss of the functional melanocytes, with possible involvement of oxidative stress. Glutathione peroxidase (GPx) is an antioxidant enzyme that protects cells against oxidative damage.

Aim

To examine serum GPx levels in patients with vitiligo and to relate the findings to the clinical features.

Patients and Methods

The study group included 60 patients with vitiligo and 30 matching healthy controls. GPx activity was evaluated using enzyme-linked immunosorbent assay.

Results

We found a significant decrease in serum GPx activity level in the patients with vitiligo compared to the healthy controls (0.29 ± 0.14 versus 0.47 ± 0.13, p < .001). The levels were significantly low in skin phenotypes III and IV ( p < .001). Higher levels were also observed with increasing age (≥ 14 years), prolonged disease duration (≥ 3 years), and generalized and extensive vitiligo (<50%). However, these variations were statistically insignificant.

Conclusions

Low levels of serum GPx activity, indicative of a disturbed oxidant-antioxidant system, may contribute to the development of vitiligo.

Can systemically generated reactive oxygen species help to monitor disease activity in generalized vitiligo? A pilot study

Background:

Generalized vitiligo is a disease with unpredictable bursts of activity, goal of treatment during the active phase being to stabilize the lesions. This emphasizes the need for a prospective marker for monitoring disease activity to help decide the duration of therapy.

Aims and Objectives:

In the present study, we examined whether reactive oxygen species (ROS) generated in erythrocytes can be translated into a marker of activity in vitiligo.

Materials and Methods:

Level of intracellular ROS was measured flow cytometrically in erythrocytes from venous blood of 21 patients with generalized vitiligo and 21 healthy volunteers using the probe dichlorodihydrofluorescein diacetate.

Results:

The levels of ROS differed significantly between patients and healthy controls, as well as between active versus stable disease groups. In the active disease group, ROS levels were significantly lower in those being treated with systemic steroids than those that were not. ROS levels poorly correlated with disease duration or body surface area involved.

Conclusion:

A long-term study based on these findings can be conducted to further validate the potential role of ROS in monitoring disease activity vitiligo.

Reduced serum paraoxonase-1 levels in vitiligo: further evidence of oxidative stress

Vitiligo is a common disorder that results in depigmented areas of the skin. The pathogenesis of the disease remains unclear, but oxidative stress is one suggested cause. Oxidative stress may be induced by increasing the generation of reactive oxygen species and other free radicals. The generation of reactive oxygen species is known to be associated with a decrease in antioxidant levels. This study examined oxidative stress index in active lesions of generalized vitiligo patients. We analysed serum levels of paraoxonase 1, arylesterase, catalase, ceruloplasmin, total antioxidant capacity, and oxidative stress index in patients with active lesions of generalized vitiligo, as well as in matched, healthy controls. Serum oxidants and oxidative stress indexes were higher, and serum antioxidants were lower, in vitiligo patients compared with healthy controls. Our findings suggest that oxidative stress may play an important role in the pathogenesis of vitiligo. Paraoxonase 1 can be used as an indicator in determining oxidative stress existent in the pathogenesis of vitiligo diseases.

Impact of depressive symptoms on oxidative stress in patients with psoriasis

BACKGROUND

Depression and anxiety disorders often accompany psoriasis. Increased reactive oxygen radicals and impaired antioxidant systems are considered to play a role both in psoriasis and depression and anxiety disorders. Accordingly, in this study, we aimed to investigate the effects of depressive and anxiety symptoms on oxidative stress in patients with psoriasis.

MATERIALS AND METHODS

Hospital Anxiety and Depression Scale (HADS) forms were completed by 39 psoriasis patients and 25 volunteer controls. Serum total antioxidant capacity (TAC) and total oxidant capacity (TOC) parameters were analysed in serum samples, after which oxidative stress index (OSI) was calculated in whole study population. Laboratory data were analysed with a Kruskal-Wallis test to determine the severity of HADS and the presence of psoriasis among four groups.

RESULTS

The psoriasis patients had higher HADS scores, higher OSI and TOC levels, and lower TAC levels compared with the control group. Comparison among four groups with/without psoriasis and higher/lower HADS scores revealed statistically significant differences with regard to TAC (Kruskal-Wallis P = 0.0047) and TOC (Kruskal-Wallis P < 0.001) levels and OSI (Kruskal-Wallis P < 0.001); the difference was mainly based on the difference between cases with and without psoriasis and on HADS scores in control subjects (P < 0.05 for post hoc comparisons). TAC, TOC, and OSI levels did not differ significantly in psoriasis patients with regard to higher or lower HADS scores.

CONCLUSION

Based on the findings of this study, the presence of either psoriasis or higher HADS scores in the control subjects was associated with increased oxidative stress, whereas presence of higher HADS scores did not lead to further increase in oxidative stress in psoriatic patients.

Down-regulation of Prdx6 contributes to DNA vaccine induced vitiligo in mice

DNA vaccines are widely used against infectious agents for their ability to induce both humoral and cellular immune responses. However, safety concerns regarding autoimmune responses to DNA vaccines, particularly to certain plasmids, should not be neglected. In this study, we serendipitously found that mice inoculated with pcDNA3-ANXB1 (pcDNA3-b1) developed autoimmunity, which did not happen in pVAX-ANXB1 (pVAX-b1) inoculated mice. We also employed proteomics approaches to investigate the distinction between the two groups of DNA vaccine immunized mice. Five different proteins with three-fold or greater changes were separated and identified by two-dimensional electrophoresis. Our study verified the safety of the DNA vaccine and unveiled the underlying potential molecular mechanism of DNA vaccine delivery.

Update on childhood vitiligo

PURPOSE OF REVIEW

This review addresses recent changes in the understanding and the treatment of vitiligo vulgaris.

RECENT FINDINGS

Two target genes for vitiligo have been identified, NACHT-leucine-rich-repeat protein-1 (NALP1), part of the inflammasome cascade, and tyrosinase, the enzyme that produces melanin. Identification of reactive oxidation species has furthered the understanding of melanocyte destruction. Comorbid autoimmune disease, including thyroid autoimmunity seen in 25%, is genetically linked to generalized vitiligo and is noted in both childhood vitiligo patients and their families. Screening for vitamin deficiencies and concurrent autoimmunity can be beneficial to the overall health of the child with vitiligo. About half of all vitiligo vulgaris patients have onset of their illness during childhood, causing increased psychological stress during the formative years. Fortunately, therapy has improved as well, with the development of newer topical agents for vitiligo, including topical calcineurin inhibitors; new topical combinations such as topical corticosteroids and calcipotriene; and new technological advances including narrowband ultraviolet B and excimer laser.

SUMMARY

A cyclic approach to therapy should be used wherein topical agents are altered every 6-8 months and technology is used as an alternative after achievement of maximal topical response. With cyclic therapy and early disease intervention, good cosmetic outcomes may be achievable, particularly in localized cases.