Oxidative stress and the cholinergic system in non-segmental vitiligo: Effect of narrow band ultraviolet b.

BACKGROUND Despite exhaustive research, melanocyte disappearance and the evolution of vitiligo remain enigmatic, and although multi-factorial, oxidative stress appears as a major player. The role of cutaneous cholinergic system in vitiligo pathogenesis has also been reported in some studies. OBJECTIVE To evaluate and correlate the influence of phototherapy on cutaneous cholinergic system and oxidative stress in vitiligo. METHODS Acetyl choline (ACh), its receptors; nicotinic (nAChR) and muscarinic (mAChR); acetylcholine esterase (AChE) and H2 O2 levels were estimated in de-pigmented and re-pigmented lesions of 30 vitiligo patients before and after NB-UVB phototherapy and in 30 controls. ACh and H2 O2 levels were measured by colorimetry. AChE and acetylcholine receptors expression were measured by quantitative real-time PCR. RESULTS Mean ACh and H2 O2 levels were significantly higher in vitiligo lesions before NB-UVB (P < .001) whereas AChE enzyme level was significantly lower (P < .001) compared to both re-pigmented and control skin. Additionally, mean mAChR was significantly higher and mean nAChR was significantly lower in vitiligo lesions before NB-UVB versus controls and re-pigmented skin (P < .001). Also, H2 O2 and AChE showed negative correlation whereas ACh and mAChR showed significant positive correlation. Although all the studied parameters showed significant changes after treatment and subsequent re-pigmentation, a significant difference continued to exist between all vitiligo skin and controls. CONCLUSION Cholinergic system is strongly involved in vitiligo pathogenesis through H2 O2 inhibition of AChE which could be reversed by NB-UVB. Moreover, the strong activation of mAChRs may reflect genetic and/or acquired errors, direct up-regulation by ACh and H2 O2 or both.