These results provide new evidence for the effectiveness of EGCG in vitiligo treatment. - GreenMedInfo Summary
Epigallocatechin-3-gallate (EGCG) suppresses the trafficking of lymphocytes to epidermal melanocytes via inhibition of JAK2: Its implication for vitiligo treatment.
Biol Pharm Bull. 2015 Sep 4. Epub 2015 Sep 4. PMID: 26345342
Vitiligo is an inflammatory skin disorder in which activated T cells play an important role in its onset and progression. Epigallocatechin-3-gallate (EGCG), the major chemical constituent of green tea, exhibits remarkable anti-oxidative and anti-inflammatory properties. EGCG administration has been confirmed to decrease the risk of vitiligo; however, the underlying mechanism is undetermined. In this study, we proved that EGCG directly inhibited the kinase activity of Janus kinase 2 (JAK2). In primary cultured human melanocytes, EGCG pre-treatment attenuated IFN-γ-induced phosphorylation of JAK2 and its downstream STAT1 and STAT3 in a dose-dependent manner. We further examined the chemoattractant expression in melanocytes and demonstrated that EGCG significantly inhibited IFN-γ-induced expression of ICAM-1, CXCL10, and MCP-1 in human melanocytes. In addition, EGCG reduced the protein levels of the corresponding receptors including CD11a, CXCR3, and CCR2 in human T lymphocytes. As a consequence, adhesion of human T cells to melanocytes induced by IFN-γ was effectively suppressed by EGCG. Taken together, our results provided new evidence for the effectiveness of EGCG in vitiligo treatment and supported JAK2 as a molecular target for vitiligo medicine development.