Synergistic effects of glucocorticoid and N2-gas cold atmospheric plasma in a mouse model of atopic dermatitis.

Atopic dermatitis (AD) is characterized by impaired skin barrier function, chronic inflammation, and increased susceptibility to infection. Although topical glucocorticoids are effective, long-term use is limited by adverse effects, highlighting the need for steroid-sparing strategies. This study investigated the immunomodulatory and therapeutic effects of nitrogen-based cold atmospheric plasma (N₂-CAP), alone and in combination with topical clobetasol propionate, in murine models of burn injury and AD. Burn wounds in mice were treated daily with N₂-CAP for 15 or 60 s. A human epidermal keratinocyte cell line (HaCaT) was used to assess proliferation, scratch closure, and cytokine release following TNFα/IFNγ or Dermatophagoides farinae stimulation. Preventive and therapeutic AD models were treated daily with N₂-CAP, 0.05% clobetasol propionate (CP), or combination therapy (N₂-CAP plus reduced CP). Clinical severity, transepidermal water loss (TEWL), skin thickness, histology, immune cell infiltration, cytokine production, serum IgE, and RNA sequencing were evaluated. Daily 60 s N₂-CAP accelerated burn wound closure, enhanced keratinocyte proliferation, and reduced pro-inflammatory cytokine production in vitro. In AD models, N₂-CAP significantly reduced clinical scores, TEWL, skin thickening, and Th2 cytokines, showing efficacy comparable to that of CP. Combination therapy yielded additive therapeutic effects. Transcriptomic analysis revealed that N₂-CAP predominantly downregulated inflammatory pathways, whereas CP enhanced barrier-related gene expression; combination therapy additively modulated both processes. These findings indicate that N₂-CAP exerts significant immunomodulatory effects in experimental AD and may serve as a complementary, steroid-sparing therapeutic strategy. N₂-CAP represents a promising non-pharmacological approach for managing inflammatory skin disease.