Inhibitory effects of isoliquiritin on an atopic dermatitis model through the CD177/JAK2/STAT pathway in vitro and in vivo

BACKGROUND: Atopic dermatitis (AD) is a complex inflammatory skin condition characterized by the proliferation and activation of immune cells in skin. Isoliquiritin (ISO) is an active component purified from Glycyrrhiza glabra. This study aimed to test the therapeutic potential of ISO for AD and verify its potential molecular mechanism. METHODS: This study investigated the potential effects and possible underlying mechanisms of ISO against AD in vitro (HMC1.1 cells stimulated by phorbol-12-myristate-13-acetate and calcium ionophore A23187) and in vivo (AD-like mouse model induced by 1-chloro-2,4-dinitrochlorobenzene). RESULTS: ISO dose-dependently suppressed the viability of HMC1.1 cells. ISO inhibited the secretion of the proinflammatory factors IL-6 and IL-8 and induced the apoptosis of HMC1.1 cells. ISO suppressed the phosphorylation of CD177, JAK2, STAT1, STAT3, and STAT5, and upregulated the protein expression of BAX and cleaved caspase-3 in vitro. ISO administration markedly diminished the infiltration of immune cells (mast cells, eosinophils) in cutaneous lesions. Simultaneously, ISO treatment alleviated the formation of skin lesions and affected other AD symptoms (thickness of the epidermis and dermis, ear edema, lymph node weight, spleen index, dermatitis score) but increased the thymus index in vivo, and downregulated expression of IL-4, IL-6, IgE, and thymic stromal lymphopoietin (TSLP). CONCLUSIONS: Collectively, our findings showed that ISO administration decreased skin lesion formation by inhibiting inflammation and enhancing immunomodulation through the CD177/JAK2/STAT signaling pathway.