Vitiligo (vit-ill-eye-go) is a disease where the pigment cells of the skin called melanocytes are destroyed in certain areas. It is a common condition that affecting about 1% of all racial groups worldwide. It results in de-pigmented or white skin patches in any location on the body. Figure 1 shows an example of vitiligo at patient’s neck area. This disease can be focal and localized to one area or may affect several different areas on the body. It can also affect the mucous membranes such as the tissue inside mouth and nose and the eye. Vitiligo does not have significant health consequences and is not painful but it can have emotional and psychological consequences.
The current treatment options for vitiligo patients such as medical and surgical are aimed at restoring color to the white patches of skin. Example of medical treatments including medicines like creams, oral drug, combined medication and light therapy like ultraviolet A (UVA) or UVB light, and by removing the color from other areas so they match the white patches. On the other hand, surgical treatments include skin grafts from patient’s own tissues or tattooing small areas of the skin.
Corticosteroids, calcineurin inhibitors and vitamin D derivatives are among the widely used cure for vitiligo. Conversely, these current treatments are largely unsatisfactory (Whitton, Ashcroft & Gonzalez, 2008). For example, corticosteroid which will be applied topically is considered as a first-line treatment of vitiligo as it is low-cost and easy to be administered. Nevertheless, studies showed that the use of high-power topical corticosteroids should be used within 2 to 4 months only in order to decrease adverse effects risk.
Immunosuppressant called calcineurin inhibitor is another alternative for vitiligo treatment. Calcineurin acts to activate T cells of the immune system. Initially, it has been used in transplant patients topically. Compared to corticosteroids that cause inhibition of collagen synthesis which lead to an increased skin atrophy risk, especially during prolonged use, calcineurin inhibitors cause no risk of atrophy as the neocollagenesis does not depend from calcineurin. An example of calcineurin inhibitors is tacrolimus that can controls the activity of T lymphocytes through the inhibition of pro-inflammatory cytokines, blocking the transcription of the IL-2 genes which are important for the proliferation of cytotoxic T lymphocytes, and also inhibiting the transcription and production of IL-4, IL5, IL-10, IFN-γ and TNF-α (Kostovic & Pasic, 2005).
Figure 3. Calcineurin (Source: Wikipedia)
According to experts, vitiligo is believed to be an autoimmune disease which the immune system of one’s body mistakenly attacks and destroys the melanocytes cell in skin. In addition, some researches stated that the melanocytes destroy themselves and it is also sometimes associated with other medical conditions such as hyperthyroidism. However, until today, no exact cause of this disease is found, but there was an opinion mentioned that it involves both genetic and environmental factors.
Figure 2. Melanocytes (Source: ouhsc.edu)
Vitiligo tends to run in families and in accordance to a study, 20% of the relatives of vitiligo patients also have vitiligo, with the highest risks for children and siblings of patients. Therefore, it can be said that born with genes that make them more susceptible to developing vitiligo. These susceptibility genes may be important for the normal function of the pigment-producing cells in the skin (melanocytes) and/or in cells of the immune system (lymphocytes).
Generally, the cause of vitiligo can be investigated by identifying those disease susceptibility genes. New treatments are designed based on comprehension of those genes by depending on which genes are involved, what their normal functions are, and what genetic changes are found in vitiligo patients.
In recent years, a better understanding of vitiligo is gained through gene research. According to Al-Shobaili (2011), “there has been considerable progress in identifying susceptibility genes for vitiligo, some of which are shared with other autoimmune diseases and some of which are specific to vitiligo. The linkage and association studies also provide a strong evidence for the presence of multiple vitiligo susceptibility genes on different chromosomes. These genes may thus provide novel therapeutic and even prophylactic targets for new interventional approaches to treat and prevent vitiligo and other autoimmune diseases.” (pg. 173).
Genomic-wide scans have provided a strong support for vitiligo susceptibility genes on chromosomes 4q13-q21, 1p31, 7q22, 8p12 and 17p13, while loci of interest at 6p, 6q, 14q, 9q, 13q, 19p and 22q required further follow-up. While, functional candidate gene association analyses some candidate genes which are associated with vitiligo, such as human leukocyte antigen (HLA), vitiligo-associated protein 1 (VIT1), catalase (CAT), angiotensin-converting enzyme (ACE).
Bagherani, Yaghoobi and Omidian (2011) mentioned that zinc is a potential trace element in treatment of vitiligo as it plays an important role in the process of melanogenesis. It may be effective in prevention and treatment of vitiligo through some mechanism. A study showed that the combination of zinc and topical steroid is more effective than the topical steroid alone (Wolff et al., 2007). Zinc has the ability to prevent apoptosis of melanocytes that may control vitiligo. Therefore, it is a potential antiapoptosis factor. On the other hand, another study conducted by Mosenson et al. (2013) reported that the modified inducible heat shock protein 70 (HSP70i) prevents T cell–mediated depigmentation. As the result, 76% recovery of pigmentation was recorded and the treatment prevented relevant T cells from populating the skin.
As a conclusion, there are many potential vitiligo treatments that can be discovered specifically gene targeted therapy. The progress in this area are going to be exciting and will influence the therapeutic approaches for the suppression of vitiligo. In future, an advance in gene therapy might also possible to help susceptible or affected persons.