Re-appraisal of Keratinocytes' Role in Vitiligo Pathogenesis

BACKGROUND: Vitiligo is a common pigmentary disorder. Studies on its pathogenesis extensively investigated melanocytes' abnormalities and few studies searched for keratinocytes' role in disease development. Liver X receptor-α (LXR-α) is a member of nuclear hormone receptors that acts as a transcription factor. Its target genes are the main regulators of melanocyte functions. AIM: The aim of this study is to investigate keratinocytes' role in vitiligo pathogenesis through immunohistochemical expression of LXR-α in lesional, perilesional, and distant nonlesional vitiligo skin. MATERIALS AND METHODS: This case–control study was carried out on 44 participants. These included 24 patients with vitiligo and 20 age- and sex-matched normal individuals as a control group. Biopsies, from cases, were taken from lesional, perilesional, and distant nonlesional areas. Evaluation was done using immunohistochemical technique. RESULTS: Keratinocyte LXR-α expression was upregulated in the lesional and perilesional skin (follicular and interfollicular epidermis) compared with control skin (P <0.001 for all). There was significant association between higher histoscore (H-score) in lesional epidermis (P <0.001) and in hair follicle (P =0.001) and the presence of angiogenesis. There was significant association between higher H-score in lesional epidermis and suprabasal vacuolization (P =0.02). No significant association was found between H-score or expression percentage and clinical data of selected cases. CONCLUSION: LXR-α upregulation is associated with keratinocyte damage in vitiligo lesional skin that leads to decreased keratinocyte-derived mediators and growth factors supporting the growth and/or melanization of surrounding melanocytes. Therefore, melanocyte function and survival are affected.