Anti-inflammatory effect of astaxanthin in phthalic anhydride-induced atopic dermatitis animal model

In this study, we investigated anti-dermatitic effects of astaxanthin (AST) in phthalic anhydride (PA)-induced atopic dermatitis (AD) animal model as well as in vitro model. AD-like lesion was induced by the topical application of 5% PA to the dorsal skin or ear of Hos:HR-1 mouse. After AD induction, 100 μL of 1 mg/mL and 2 mg/mL of AST (10 μg or 20 μg/cm² ) was spread on the dorsum of ear or back skin three times a week for four weeks. We evaluated dermatitis severity, histopathological changes and changes in protein expression by Western blotting for inducible nitric oxide synthase (iNOS), cyclooxygenase-2 (COX-2) and nuclear factor-κB (NF-κB) activity. We also measured tumor necrosis factor-α (TNF-α), interleukin-1β (IL-1β), interleukin-6 (IL-6) and immunoglobulin E (IgE) concentration in the blood of AD mice by enzyme-linked immunosorbent assay (ELISA). AST treatment attenuated the development of PA-induced AD. Histological analysis showed that AST inhibited hyperkeratosis, mast cells and infiltration of inflammatory cells. AST treatment inhibited expression of iNOS and COX-2, and NF-κB activity as well as release of TNF-α, IL-1β, IL-6 and IgE. In addition, AST (5, 10 and 20 μM) potently inhibited lipopolysaccharide (LPS) (1 μg/mL)-induced nitric oxide (NO) production, expression of iNOS and COX-2 and NF-κB DNA binding activities in RAW 264.7 macrophage cells. Our data demonstrated that AST could be a promising agent for AD by inhibition of NF-κB signalling.