Role of chemokine ligand 22 in narrow-band ultraviolet B-induced pigmentation in vitiligo: an immunohistochemical study

Abstract

Background Chemokine ligand 22 (CCL22) is a heparin-binding immunomodulator protein that plays an important role in a variety of autoimmune diseases. Narrow-band ultraviolet B (NB-UVB) therapy was considered a cornerstone in the treatment of vitiligo. However, the mechanism of action of NB-UVB in vitiligo has not been completely elucidated. Objective To study the hypothesized role of CCL22 in vitiligo etiopathogenesis and to detect its possible role in NB-UVB-induced pigmentation in vitiligo through its lesional immunohistochemical evaluation in patients with vitiligo before and after ultraviolet B phototherapy. Patients and methods A total of 33 patients with vitiligo versus 20 patients of age-matched, sex-matched, and skin phototype-matched healthy controls were enrolled in this case–control study. Patients were treated with NB-UVB three sessions weekly for 12 weeks. Vitiligo Area Scoring Index score was evaluated before and after NB-UVB sessions. For patients with vitiligo, baseline CCL22 immunohistochemical staining was estimated, and compared with that of controls and with its posttreatment data in those patients. Results Baseline CCL22 immunohistochemical studied parameters were insignificantly lower in patients with vitiligo than controls except its cellular localization (P<0.001). After 12 weeks of NB-UVB, these CCL22 immunohistochemical parameters were significantly up-regulated (P<0.001). Although there was a negative correlation between the improvement in Vitiligo Area Scoring Index score and CCL22 H score, this correlation could not reach level of significance (r=0.086, P=0.653). Conclusion Although we could not confirm that CCL22 protein has an active role in the pathogenesis and development of vitiligo, we concluded that CCL22 chemokine may take part in photo-induced melanogenesis. Yet, the mechanism of NB-UVB-induced pigmentation is still far from being clarified, and further studies are needed.