Interferon-c Induces Senescence in Normal Human

Background: Interferon-c (IFN-c) plays an important role in the proceedings of vitiligo through recruiting lymphocytes to the lesional skin. However, the potential effects of IFN-c on skin melanocytes and the subsequent contribution to the vitiligo pathogenesis are still unclear. Objective: To investigate the effects of IFN-c on viability and cellular functions of melanocytes. Methods: Primary human melanocytes were treated with IFN-c. Cell viability, apoptosis, cell cycle melanin content and intracellular reactive oxygen species (ROS) level were measured. mRNA expression was examined by real-time PCR. The release of interleukin 6 (IL-6) and heat shock protein 70 (HSP-70) was monitored by ELISA. b-galactosidase staining was utilized to evaluate melanocyte senescence. Results: Persistent IFN-c treatment induced viability loss, apoptosis, cell cycle arrest and senescence in melanocytes. Melanocyte senescence was characterized as the changes in pigmentation and morphology, as well as the increase of b-galactosidase activity. Increase of p21Cip1/Waf1 protein was evident in melanocytes after IFN-c treatment. IFN-c induction of senescence was attenuated by siRNAs against p21, Janus kinase 2 (JAK2) or signal transducer and activator of transcription 1 (STAT1), but not by JAK1 siRNA nor by p53 inhibitor pifithrin-a. IFN-c treatment increased the accumulation of intracellular ROS in melanocytes, while ROS scavenger N-acetyl cysteine (NAC) effectively inhibited IFN-c induced p21 expression an