Astragaloside IV suppresses the proliferation and inflammatory response of human epidermal keratinocytes and ameliorates imiquimod-induced psoriasis-like skin damage in mice

The primary pathological features of psoriasis include excessive epidermal keratinocytes and infiltration of inflammatory cells, which are pivotal targets for psoriasis therapy. Astragaloside IV (AS-IV), the principal active compound of astragalus, exhibits anti-inflammatory, antioxidant, and immune-modulatory properties. This study aims to investigate AS-IV's anti--psoriatic effects and underlying mechanisms. Normal human epidermal keratinocytes (NHEKs) were stimulated with a combination of TNF-α, IL-17A, IL-1α, IL-22, and oncostatin M (M5) to replicate psoriatic keratinocyte pathology <i>in vitro</i>. Cell proliferation was assessed using CCK8 and EDU staining. Pro-inflammatory cytokine levels were measured via qRT-PCR. In addition, an imiquimod (IMQ)-induced psoriasis mouse model was utilized. Skin histology changes were evaluated with HE staining, while IL-6 and TNF-α levels in mouse serum were quantified using ELISA. NF-κB pathway protein expression was analyzed by western blotting. The results demonstrated that AS-IV inhibited M5-induced proliferation of NHEKs. AS-IV reduced M5-stimulated IL-1β, IL-6, IL-8, TNF-α, IL-23, and MCP-1 expression in NHEKs. Moreover, M5-induced phosphorylation of IκBα and p65 was significantly attenuated by AS-IV. Furthermore, AS-IV application ameliorated erythema, scale formation, and epidermal thickening in IMQ-induced psoriasis-like mouse models. AS-IV also decreased IL-6 and TNF-α levels in mouse serum and inhibited IκBα and p65 phosphorylation in skin tissues. However, prostratin treatment reversed these effects. These findings underscore AS-IV's capacity to mitigate M5-induced NHEK proliferation and inflammation. AS-IV shows promise in alleviating IMQ-induced psoriasis-like skin lesions and inflammation by suppressing the NF-κB pathway.