Objective: To evaluate autophagy of melanocytes and its mechanism in patients with vitiligo and to analyze its correlation with clinical types of vitiligo.
Methods: Nine cases of segmental vitiligo (SV) and 11 cases of generalized vitiligo (GV) were recruited in Hangzhou Third Hospital between May 2014 and June 2015. Six people with healthy skin were recruited as controls. Epidermal melanocytes were obtained from the normal colour skin around the white spot area in SV and GV patients and from foreskin in controls for culture in vitro. Cultures for each group contained negative control and rapamycin (30 nmol/L) sub-groups. The autophagy was observed using transmission electron microscopy (TEM) and immunofluorescence laser scanning confocal microscope (LSCFM). Protein expressions of microtube-associated protein light chain 3 (LC3Ⅱ) and microphthalmia-associated transcription factor (MITF), tyrosinase (TYR), tyrosinase related protein (TYRP)1, and TYRP2 were detected by Western blot.
Results: (1)Autophagy of melanocytes was observed under TEM and LSCFM in both SV and control groups before rapamycin treatment, but not in GV patients. The expressions of autophagosome and LC3Ⅱ protein were increased in melanocytes in SV, GV and control groups after autophagy induction(SV group 0.58±0.10 vs 0.37±0.06; GV group 0.57±0.16 vs 0.22±0.08; control group 0.67±0.09 vs 0.46±0.12), and the autophagy intensity was higher in the GV group compared to the SV group and the control group. (2)Before autophagy induction, the expressions of MITF, TYR, TYRP1, and TYRP2 protein were lower in the GV and SV patients compared with the control group; after autophagy induction, the expressions of MITF, TYR, and TYRP1 statistically significantly increased in melanocytes in all the three groups(all P<0.05), while TYRP2 protein expression was not significantly changed (all P>0.05).
Conclusions: Autophagy of melanocytes may be present in vitiligo and affect the expression of functional molecules, and is related with clinical type of vitiligo.