Critical appraisal of the oxidative stress pathway in vitiligo : a systematic review and meta-analysis

Background: The pathogenesis of vitiligo remains a topic of extensive debate. This is partly due to the moderate efficacy of current treatments. The role of the oxidative stress pathway in vitiligo is a popular although controversial research topic. Objective: To clarify the role of the oxidative stress pathway in vitiligo compared to other inflammatory skin disorders and to assess the therapeutic role of antioxidants. Methods: We conducted a systematic search of the existing literature on the aberrancies of the oxidative stress pathway in vitiligo. Subsequently, the efficacy of both topical and oral antioxidants in clinical trials was investigated. Results: A deregulated oxidative pathway is clearly evident with elevated superoxide dismutase, decreased catalase and increased lipid peroxidation. However, similar results have been obtained in other inflammatory skin diseases such as psoriasis, atopic dermatitis, lichen planus and urticaria. This questions the unique role of oxidative stress in the development of vitiligo. Some isolated successes have been reported with oral ginkgo biloba, polypodium leucotomos and vitamin C and E preparations, while other clinical trials have failed to show reproducible results. The use of topical antioxidants delivers in general no beneficial results. Conclusion: The oxidative pathway is affected in vitiligo, but its unique initiating or contributory role in the pathogenesis is less evident. Interesting data support the added value of oral antioxidants in vitiligo although confirmatory studies are missing