Portulaca oleracea polysaccharide alleviates UVB-induced solar dermatitis in association with macrophage...

Ultraviolet B (UVB) radiation contributes to solar dermatitis by inducing oxidative stress, inflammation, and skin barrier disruption. Portulaca oleracea polysaccharide (POP) possesses documented immunomodulatory properties, but its role in UVB-induced solar dermatitis remains unclear. In this study, we evaluated the photoprotective effects of POP using macrophage-based assays, keratinocyte co-culture systems, and a mouse model of UVB-induced solar dermatitis. POP skewed macrophages toward an M2-like phenotype and modulated their inflammatory responses. Furthermore, POP-conditioned macrophages attenuated oxidative stress in UVB-injured keratinocytes and enhanced their proliferation and migration. In vivo, topical application of POP ameliorated UVB-induced skin damage and barrier dysfunction; these protective effects were markedly attenuated following macrophage depletion. Collectively, our findings suggest that POP alleviates UVB-induced solar dermatitis, at least in part, through macrophage-mediated immunomodulation, supporting its further exploration as a natural candidate for photoprotective intervention.