Amygdalin Regulates FOXO3a Signaling to Inhibit Oxidative Stress and Improve Alopecia Areata in Mice

This paper aims to explore the mechanism of amygdalin's (AMG) therapeutic effect on alopecia areata (AA). Hematoxylin-eosin staining was used to probe AMG's hepatorenal toxicity. After establishing the AA model of C3H/HeJ mice and H2O2-damaged human primary epidermal melanocytes (HPEMs), and following AMG intervention, the reactive oxygen species (ROS) content and the levels of forkhead box O3A (FOXO3a) protein and gene were monitored. Biochemical kits or ‌enzyme-linked immunosorbent assay‌ were used to detect the contents of superoxide dismutase (SOD), catalase (CAT), glutathione peroxidase 4 (GPX-4), malondialdehyde (MDA), interleukin-15 (IL-15), interferon-gamma (IFN-γ), and interleukin-6‌ (IL-6). A Western blot was performed to assess the levels of MHC I, IL-15, FOXO3a, SOD, CAT, GPX-4, IFN-γ, IL-6, and IL-15. ChIP-PCR was performed to assess the enrichment of AMG at the promoters of SOD, CAT, and GPX-4 in FOXO3a. Meanwhile, ROS, apoptosis, and the protein and gene levels of FOXO3a, SOD, CAT, and GPX-4 in HPEMs with low FOXO3a expression were investigated. AMG has no potential liver or kidney toxicity and can reduce the expression of MHC I and IL-15 proteins in skin, as well as the serum IL-15. AMG can enhance the expression of the FOXO3a protein and gene in the skin, as well as the levels of SOD, CAT, and GPX-4, while reducing ROS and MDA levels. AMG can inhibit MHC I, IFN-γ, IL-6, and IL-15, MDA, apoptosis, and ROS production in HPEMs, and increase SOD, CAT, and GPX-4 contents. Importantly, AMG can upregulate the expression of the FOXO3a, SOD, CAT, and GPX-4 genes and proteins, and enrich FOXO3a at the promoters of SOD, CAT, and GPX-4. These data suggest that AMG can promote FOXO3a expression and inhibit oxidative stress and inflammatory responses, thereby improving AA in C3H/HeJ mice.