Rosacea is a facial chronic inflammatory skin disease with dysfunction of immune and vascular system. Artemisinin (ART), an anti-malaria drug, was reported to have several effects including anti-inflammation and anti-angiogenesis activities. However, the role of ART on rosacea remains unclear.

To investigate the effects and molecular mechanism of ART on rosacea.

In rosacea-like mouse model, the phenotype of rosacea lesions was evaluated by redness score, the inflammatory biomarkers were analyzed by qPCR, and the infiltration of inflammatory cells were assessed by IHC analysis and immunofluorescence. In vitro, LL37-induced expression of inflammatory factors in HaCaT cells was detected by qPCR, potential signaling pathways were detected by Western blotting or immunofluorescence. Migration ability of human umbilical vein endothelial cells (HUVECs) was evaluated by cell scratch and transwell assays.

The skin erythema and histopathological alteration, as well as the elevated pro-inflammatory factors (IL-1β, IL6, TNFα) and TLR2 were significantly ameliorated by ART treatment in LL37-induced rosacea-like mice. In addition, ART reduced the infiltration of CD4⁺ T cells, macrophages and neutrophils, and repressed the expression of immune cells related chemokines (CXCL10, CCL20, CCL2 and CXCL2) in mouse lesions. In HaCaT cells, ART significantly decreased the LL37-induced expression of inflammatory biomarkers. Moreover, we found that ART inhibited rosacea-like inflammation via NF-kB signaling pathways in HaCaT cells. Finally, for vascular dysregulation, ART repressed the angiogenesis in mouse model and inhibited the LL37-induced HUVECs migration in vitro.

ART ameliorated rosacea-like dermatitis by regulating immune response and angiogenesis, indicating that it could represent an effective therapeutic option for patients with rosacea.