Hispidin Ameliorates Acute Ultraviolet B-Induced Skin Inflammation by Targeting Reactive Oxygen Species-Dependent Neutrophil Extracellular Trap Formation.

Excessive neutrophil extracellular trap (NET) formation (NETosis), frequently associated with reactive oxygen species (ROS), exacerbates cutaneous inflammation induced by acute ultraviolet B (UVB) exposure. Although hispidin has potent antioxidant activity, its protective effects against acute UVB-induced skin inflammation and its relationship with NET-associated responses remain unclear. We investigated the effects of topical hispidin on acute UVB-induced skin injury in mice and examined its effects on ROS-associated NET-related responses in differentiated HL-60 cells. In a mouse model, topical hispidin (0.1% and 0.5%) ameliorated UVB-induced skin damage in a dose-dependent manner, as evidenced by improved clinical and histological findings. Hispidin treatment was associated with reduced systemic oxidative stress and decreased cutaneous expression of CXCL2, C5a, IL-1β, NLRP3, Ly6G, PAD4, and citrullinated histone H3. In differentiated HL-60 cells, hispidin reduced ROS-associated signals and suppressed PMA-triggered extracellular DNA release, but did not suppress A23187-triggered extracellular DNA release under experimental conditions. Cell viability analysis showed that hispidin did not significantly affect differentiated HL-60 cell viability at tested concentrations under the present experimental conditions. Topical hispidin alleviates acute UVB-induced skin inflammation by suppressing neutrophil infiltration and NET-related inflammatory responses. Hispidin may therefore represent a promising candidate as a topical modulator of oxidative stress- and NET-associated skin inflammation.