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ORIGINAL ARTICLE
Year : 2020  |  Volume : 33  |  Issue : 3  |  Page : 1021-1025

Role of β-catenin in vitiligo: a clinical and immunohistochemical study


1 Department of Dermatology, Andrology and STDs, Faculty of Medicine, Menoufia University, Al Minufya, Egypt
2 Department of Pathology, Faculty of Medicine, Menoufia University, Al Minufya, Egypt

Date of Submission14-Jan-2019
Date of Decision03-Mar-2019
Date of Acceptance05-Mar-2019
Date of Web Publication30-Sep-2020

Correspondence Address:
Heba N. N. Shehata
Batanoon, Al Minufya
Egypt
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Source of Support: None, Conflict of Interest: None


DOI: 10.4103/mmj.mmj_13_19

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  Abstract 


Objective
This study aimed at evaluating the immunohistochemical expression of β-catenin in the involved skin in vitiligo patients and to correlate its evaluated expression with the available clinicopathological parameters in those patients.
Background
Vitiligo is an autoimmune skin disorder in which the loss of melanocytes is mainly attributed to defective autoimmune mechanisms, cytotoxic mechanisms, an intrinsic defect of melanocytes, oxidant–antioxidant mechanisms, and neural mechanisms. The assessment of maintenance of vitiligo could be related to β-catenin expression. The treatment of vitiligo remains a challenge.
Patients and methods
Thirty-five patients with different degrees of vitiligo severity versus 20 patients of age-matched and sex-matched healthy controls were enrolled in this study. Biopsies were taken from vitiliginous lesion of patients and from healthy skin of controls.
Results
The relative expression of β-catenin protein in vitiligo patients showed nonsignificant differences between vitiligo cases and their matched controls regarding all studied parameters (P > 0.05) except for cellular localization, which was mainly cytoplasmic in vitiligo cases (25, 80.6%) versus 50% in the control group (P = 0.001).
Conclusion
β-Catenin may have an active role in the pathogenesis of vitiligo.

Keywords: β-catenin, immunohistochemical, vitiligo


How to cite this article:
Shoeib MA, Farag AG, Al-Sharaky DR, Hassan RA, El-Shafey EN, Shehata HN. Role of β-catenin in vitiligo: a clinical and immunohistochemical study. Menoufia Med J 2020;33:1021-5

How to cite this URL:
Shoeib MA, Farag AG, Al-Sharaky DR, Hassan RA, El-Shafey EN, Shehata HN. Role of β-catenin in vitiligo: a clinical and immunohistochemical study. Menoufia Med J [serial online] 2020 [cited 2020 Oct 22];33:1021-5. Available from: http://www.mmj.eg.net/text.asp?2020/33/3/1021/296647




  Introduction Top


Vitiligo is a common, noncontagious disorder, characterized by progressive patchy loss of skin pigmentation. It affects 0.1–2% of the world population with no sexual or racial preference and appear at any age, but has been most frequently observed in the first two decades, with significant decrease in the quality of life of affected cases [1].

Vitiligo is a multifactorial polygenic disorder with a complex pathogenesis. Several theories have been proposed about the pathogenesis of vitiligo including autoimmune mechanisms [2]. However, the precise cause behind melanocytes destruction remains unknown [3].

β-Catenin is an integral structural component of cadherin-based adherens junctions, and the key nuclear effector of canonical Wnt signaling in the nucleus [4].

The Wnt proteins have fundamental roles in controlling proliferation, cell-fate determination, and differentiation of a variety of cells, including melanocytes [5].

A canonical Wnt signaling pathway through the activation of Frizzled receptor induces accumulation of β-catenin in the cytosol, leading to the regulation of the transcription of the melanogenesis-associated transcription factor gene following its translocation to the nucleus. Melanogenesis-associated transcription factor, which acts as a master regulator of melanogenesis and melanocyte survival, can be affected by several signaling pathways, including the Wnt pathway [6]. It was reported that the mRNA expression of β-catenin in the depigmented epidermis were significantly lower compared with the normally pigmented epidermis [7]. Moreover, it was found that low expressions of β-catenin were observed in vitiligo lesions compared with nonlesional skin [8].

This study aimed at evaluating the immunohistochemical expression of β-catenin in the involved skin in vitiligo patients and to correlate its evaluated expression with the available clinicopathological parameters in those patients.


  Patients and Methods Top


This prospective case–control study was carried out on 35 patients with variable degrees of vitiligo severity. They were recruited from the Dermatology Outpatient Clinic, Faculty of Medicine, Menoufia University Hospital from May 2016 to March 2017 (group 1). Additionally, 20 persons of age, sex, Fitzpatrick skin phototype, and occupation-matched healthy patients attending the Plastic Surgery Department were included as controls (group 2). A written consent form approved by the Committee of Human Rights in Research in Menoufia University was obtained from every patient before the study initiation.

Inclusion and exclusion criteria

Vitiligo patients from both sex without treatment of their vitiligo in the last 1 month were included. However, those who are under treatment were excluded from the study.

Each of the vitiligo patients was subjected to: full history taking and clinical examination to identify any excluding factor. Dermatological examination was performed including vitiligo area severity index score to assess severity of vitiligo [9].

Skin biopsies

Punch skin biopsies from the involved skin of vitiligo patients and normal healthy skin of controls were taken under local anesthesia. Each specimen was submitted to routine tissue processing to be embedded in paraffin blocks. For each specimen, two sections of 4 μm thickness were cut.

Histopathological evaluation

One section was cut for hematoxylin and eosin staining to be examined by a light microscope and assess the pathological changes.

Immunohistochemical staining

Other sections were cut on poly l lysine coated slides for IHC staining using purified rabbit polyclonal antibody (cat. # GTX101435) raised against β-catenin which was received in a concentrated form of 0.1 ml from Abcam company (http://www.abcam.com). The procedure of IHC staining was done according to the received datasheet of the used antibodies.

Immunohistochemically, β-catenin expression is confirmed by cytoplasmic, nuclear, and/or membranous staining according to the supplier's datasheet and was evaluated in both the epidermis and the dermis. In case of positively expressed cells, the percentage of the positive cell was assessed at ×200 magnification field [10]. Intensity of the stain was graded as mild, moderate, or strong. Histoscore (H-score) was calculated (H-score = 1 × percent of mildly stained cells + 2 × percent moderately stained cells + 3 × percent of strongly stained cells) (Smyth et al., 2004). β-Catenin stain distribution patterns were categorized as either patchy or diffuse and its cellular localizations were assigned as either cytoplasmic, nuclear, and/or membranous.

Ethical consideration

The study was approved by the Ethics Committee of Menoufia Faculty of Medicine and an informed consent was obtained from all participants before the study was started.

Statistical analysis of data

Data were collected, tabulated, and statistically analyzed using a personal computer with the statistical package for the social sciences (SPSS), version 20 (IBM, Armonk, New York, USA).

Descriptive statistics were expressed as percentage, mean and SD. Analytical statistics included χ2-test to compare between qualitative data, Fisher's exact test was used in the analysis of 2 × 2 contingency tables when at least 25% of cells has an expected number of less than 5; t-test was used in comparison between two normally distributed groups. Mann–Whitney (U-test) was used in comparison between two groups that are not normally distributed. The Wilcoxon signed-rank test was used when comparing two related samples, matched samples, or repeated measurements on a single sample to assess whether their population mean ranks differ. McNemar's test of significance was used on paired (e.g., pre and post) qualitative data. Marginal homogeneity test of significance was used on paired (e.g., pre and post) qualitative data when a category of the sample is more than two. Kruskal–Wallis test (K) was used for comparison between more than two groups not normally distributed. Spearman's correlation (r); was used to measure the association between two not normally distributed quantitative variables or one quantitative and one qualitative ordinal variable. A P value of less than 0.05 was considered statistically significant.


  Results Top


Personal and clinical data of the studied groups: the personal data of the studied subjects are illustrated in [Table 1].
Table 1: Comparison between the studied groups regarding personal data

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β-Catenin immunohistochemical staining in the studied group: the investigated baseline β-catenin immunohistochemical staining in vitiligo patients showed that β-catenin expression was positive in 31 (88.6%) patients, in which cytoplasmic localization was observed in 25 (80.6%) cases; nuclear localization in five (16.1%) cases and only one (3.2%) case was membranocytoplasmic. The intensity of β-catenin immunoreactivity was mild in 15 (48.4%) cases, moderate in 11 (35.5%) cases, and strong in five (16.1%) cases. It was of patchy distribution in 19 (61.3%) cases and of diffuse pattern in 12 (38.7%) cases. The percent of β-catenin immunoreactivity ranged from 5 to 90 with a mean ± SD of 44.5 ± 27.3 and a median value of 45. H-score ranged from 5 to 270 with a mean ± SD of 89.3 ± 80.01 and a median value of 70 [Figure 1].
Figure 1: β-Catenin immunostaining in vitiliginous skin showed mild to moderate diffuse cytoplasmic expression of β-catenin in the epidermis, mainly confined to the stratum basalis (red arrow) (immunoperoxidase ×400).

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β-Catenin immunohistochemical profile in the control group: however, in the normal skin of controls showed positive β-catenin expression in 18 (90%) sections, where half of them nine (50%) were of cytoplasmic localization. Regarding β-catenin intensity, four (22.2%) sections were mild, 11 (61.1%) sections were moderate, and three (16.7%) sections were strong. It was of patchy distribution in most of the examined sections (77.8%). The percent of β-catenin immunoreactivity ranged from 10 to 90 with a mean of 32.78 ± 28.2 and a median value of 25. H-score ranged from 10 to 270 with a mean of 75.5 ± 82.83 and a median value of 50 [Figure 2].
Figure 2: β-Catenin immunostaining in normal skin showed moderate cytoplasmic expression of β-catenin, mainly confined to the stratum basalis (red arrow) (immunoperoxidase ×400).

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Comparison between β-catenin immunohistochemical staining in the studied cases and controls: the investigated β-catenin immunohistochemical staining showed nonsignificant differences between vitiligo cases and their matched controls regarding all studied parameters (P > 0.05) except for cellular localization, which was mainly cytoplasmic in vitiligo cases (25, 80.6%) versus 50% in the control group (P = 0.001) [Table 2].
Table 2: Comparison between β-catenin immunohistochemical staining in studied cases and controls

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  Discussion Top


Fiedler et al. [11] reported that β-catenin was found in all sections from normal human tissues including the skin. β-Catenin is part of a protein complex that form the so-called adherens junctions.Consistent with our findings, Metcalfe and Bienz [12] found that these cell–cell adhesion complexes are necessary for the creation and maintenance of epithelial cell layers and barriers. As a component of the complex, β-catenin can regulate cell growth and adhesion between cells. It may also be responsible for transmitting the contact inhibition signal that causes the cells to stop dividing once the epithelial sheet is complete.

Confirming these findings, this study demonstrated that β-catenin immunoreactivity was observed in 90% of examined sections of the control group and half of them were of cytoplasmic localization.

Herein, we observed nonsignificant differences between vitiligo patients and the control group regarding β-catenin immunoreactivity except for its cellular localization that was of significant cytoplasmic localization in vitiliginous skin (P = 0.001). Moreover, Kim and Lee [8] showed lower expressions of β-catenin in vitiligo lesions compared with nonvitiligo skin. Furthermore, Oh et al. [7] reported that the mRNA expression of β-catenin in the depigmented epidermis was significantly lower compared with the normally pigmented epidermis of vitiligo patients. This difference could be attributed to the small sample size in this study.

Additionally, our results showed that β-catenin was mainly cytoplasmic and only 3.2% of the examined sections had membranocytoplasmic localization with absence of the nucleocytoplasmic localization of β-catenin in vitiligo cases. Likewise, Wagner et al. [13] found that β-catenin was the major cytoplasmic partner of E-cadherin at the plasma membrane, and was discontinuously distributed in, or absent from, melanocyte membranes in vitiligo patients.


  Conclusion Top


β-Catenin may play a role in the development or maintenance of vitiligo.

Financial support and sponsorship

Nil.

Conflicts of interest

There are no conflicts of interest.



 
  References Top

1.
Kumar CM, Sathisha UV, Dharmesh S, Rao AG, Singh SA. Interaction of sesamol (3,4-ethylenedioxyphenol) with tyrosinase and its effect on melanin synthesis. Biochimie 2011; 93:562–569.  Back to cited text no. 1
    
2.
Farag AG, Haggag MM, Muharram NM, Mahfouz R, Elnaidany NF, Abd El Ghany HM. Is vitamin D a participant in narrow-band ultraviolet B-induced pigmentation in patients with vitiligo?. J Egypt Womens Dermatol Soc 2018; 15:30–34.  Back to cited text no. 2
    
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Gauthier Y, Cario Andre M, Taïeb A. A critical appraisal of vitiligo etiologic theories. Is melanocyte loss a melanocytorrhagy? Pigment Cell Res 2003; 16:322–332.  Back to cited text no. 3
    
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Valenta T, Hausmann G, Basler K. The many faces and functions of β-catenin. EMBO J 2012; 31:2714–2736.  Back to cited text no. 4
    
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Oh SH, Kim JY, Kim MR, Do JE, Shin JY, Hann SK. DKK1 is highly expressed in the dermis of vitiligo lesion: is there association between DKK1 and vitiligo. J Dermatol Sci 2012; 66:163–165.  Back to cited text no. 7
    
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Kim NH, Lee AY. Reduced aquaporin3 expression and survival of keratinocytes in the depigmented epidermis of vitiligo. J Invest Dermatol 2010; 130:2231–2239.-  Back to cited text no. 8
    
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Hamzavi H, Jain D, McLean J, Shapiro H, Zeng, Lui H. Parametric modeling of narrowband UV-B phototherapy for vitiligo, using a novel quantitative tool: the vitiligo area scoring index. Arch Dermatol 2004; 140:677–683.  Back to cited text no. 9
    
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Bahnassy AA, Zekri AR, El-Houssini S, El-Shehaby AM, Mahmoud MR, Abdallah S, et al. Cyclin A and cyclin D1 as significant prognostic markers in colorectal cancer patients. BMC Gastroenterol 2004; 23:4–22.  Back to cited text no. 10
    
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Fiedler M, Mendoza-Topaz C, Rutherford TJ, Mieszczanek J, Bienz M. Dishevelled interacts with the DIX domain polymerization interface of Axin to interfere with its function in down-regulating β-catenin. Proc Natl Acad Sci USA 2011; 108:1937–1942.  Back to cited text no. 11
    
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Metcalfe C, Bienz M. Inhibition of GSK3 by Wnt signalling – two contrasting models. J Cell Sci 2011; 124(Pt 21):3537–3544.  Back to cited text no. 12
    
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Wagner RY, Luciani F, Cario-André M, Rubod A, Petit V, Benzekri L, et al. Altered E-cadherin levels and distribution in melanocytes precede clinical manifestations of vitiligo. J Invest Dermatol 2015; 135:1810–1819.  Back to cited text no. 13
    


    Figures

  [Figure 1], [Figure 2]
 
 
    Tables

  [Table 1], [Table 2]



 

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