This study was conducted to monitor the macrophage infiltration of atopic dermatitis (AD)-like skin lesions and to evaluate the effects of anti-AD therapeutic agents in immunocompetent mice via optical reporter-gene-based molecular imaging. The enhanced firefly luciferase (effluc)-expressing macrophage cell line (Raw264.7/effluc) was intravenously introduced into mice with 2,4-dinitrochlorobenzene (DNCB)-induced AD, followed by bioluminescent imaging (BLI). After in vivo imaging, AD-like skin lesions were excised, and ex vivo imaging and Western blotting were conducted to determine the presence of infused macrophages. Finally, the therapeutic effect of dexamethasone (DEX), an AD-modulating agent, was evaluated via macrophage tracking. In vivo imaging with BLI revealed the migration of the reporter macrophages to DNCB-induced AD-like skin lesions on day 1 post-transfer. The greatest recruitment was observed on day 3, and a decline in BLI signal was observed on day 14. Notably, in vivo BLI clearly showed the inhibition of the reporter macrophage infiltration of DNCB-induced AD-like skin lesions by DEX, which was consistent with the reduced AD symptoms observed in DEX-treated mice. We successfully visualized the macrophage migration to DNCB-induced AD-like skin lesions, proving the feasibility of macrophage imaging for evaluating AD-regulating drugs in living organisms.
Keywords: atopic dermatitis; bioluminescence imaging (BLI); cell tracking; enhanced firefly luciferase gene (effluc); reporter macrophages.