Anti-inflammatory Effects of Achillea millefolium on Atopic Dermatitis-Like Skin Lesions in NC/Nga Mice

Achillea millefolium L. (AM) is an aromatic herb with a variety of pharmacological properties, such as anti-inflammatory and anti-allergic activities. However, AM's effects on atopic dermatitis (AD) have not been investigated. This study evaluates the anti-AD activity of 50% ethanol-extracted AM in murine macrophage Raw 264.7 cells, in tumor necrosis factor-alpha/interferon-gamma (TNF-alpha/IFN-gamma)-stimulated human immortal keratinocyte HaCaT cells in vitro, and in Biostir-AD-treated NC/Nga mice in vivo. The results showed that AM significantly downregulated expression of pro-inflammatory cytokines, such as INOS, COX-2, and interleukin (IL)-6 in lipopolysaccharide (LPS)-treated Raw 264.7 cells. The mRNA expressions of INOS, COX-2, and IL-6 decreased by 76.1%, 69.3%, and 31.8%, respectively. Overexpression of chemokines, such as activation-regulated chemokine and macrophage-derived chemokine, regulated on activation of normal T-cell expressed and secreted, and IL-8 was inhibited by 70.01%, 52.91%, 73.53%, and 18.93%, respectively, in TNF-alpha/IFN-gamma-stimulated HaCaT cells by downregulating the mitogen-activated protein kinase, I kappa B alpha, and the signal transducer and activator of transcription 1 signaling pathways. AD-like symptoms, such as elevated serum immunoglobin E levels, epidermal thickening, high dermatitis severity score, transepidermal water loss, and reduced skin hydration, were relieved by the dietary administration of AM in Biostir-AD-treated NC/Nga mice. In addition, filaggrin expression increased significantly in AM-treated groups. These results suggest that AM could be a useful candidate for AD treatment.