Our finding demonstrated that LED photomodulation with 585nm wavelength suppressed melanin content in HEMs, and the effect was caused by its dose-dependent inhibition on melanogenesis and the induction of HEMs autophagy. This may provide new insights into the efficacy of LED photomodulation in the treatment of hyperpigmentation disorders.

Autophagy is a process involving the self-digestion of components that participates in anti-oxidative stress responses and protects cells against oxidative damage. However, the role of autophagy in the anti-oxidative stress responses of melanocytes remains unclear. To investigate the role of autophagy in human epidermal melanocytes, we knocked down and overexpressed ATG7, the critical gene of autophagy, in normal human epidermal melanocytes. We demonstrated that ATG7-dependent autophagy could affect melanin content of melanocytes by regulating melanogenesis. Moreover, suppression of ATG7-dependent autophagy inhibits proliferation and promotes oxidative stress-induced apoptosis of melanocytes, whereas enhancement of ATG7-dependent autophagy protects melanocytes from oxidative stress-induced apoptosis. Meanwhile, deficiency of ATG7-dependent autophagy results in premature senescence of melanocytes under oxidative stress. Notably, we verified that ATG7-dependent autophagy could alter oxidative stress homeostasis by regulating reactive oxygen species (ROS) production, nuclear factor erythroid 2-related factor 2 (Nrf2) antioxidant pathway, and the activity of several antioxidant enzymes in melanocytes. In conclusion, our study suggested that ATG7-dependent autophagy is indispensable for redox homeostasis and the biological functions of melanocytes, such as melanogenesis, proliferation, apoptosis, and senescence, especially under oxidative stress.

Summary Background Up till now, there is no standardized and satisfactory treatment strategy for Riehl’s melanosis. Objective In this pilot study, we evaluated the efficacy and safety of a novel combination therapy with oral administration of tranexamic acid (TA) and Glycyrrhizin compound for recalcitrant Riehl’s melanosis. Methods Ten patients with Riehl’s melanosis were recruited in this study. After elimination of potential contraindication, all patients were treated with 500 mg TA together with 150 mg Glycyrrhizin compound per day orally for 3 months, followed by 500 mg TA per day orally alone for another 3 months. Lesions were imaged by reflectance confocal microscopy (RCM), dermatoscopy, and VISIA® Complexion Analysis System monthly. Mexameter was adopted to evaluate Melanin Index (MI) and Erythema Index (EI). Clinical outcome scores were given by both physicians and patients. Results Seven out of ten patients received “marked improvement”, while two received “moderate improvement” and one “minimal improvement” at the final visit. Both mean MI and EI were significantly decreased compared with baselines. Furthermore, RCM and dermatoscopy analyses confirmed the improvement of pigmentation and erythema with decreased pigment granules and telangiectatic vessels. Conclusion Oral administration of TA in combination with Glycyrrhizin compound may be an effective therapy for Asian patients with recalcitrant Riehl’s melanosis.