Synergistic topical application of salt-processed Phellodendron amurense and Sanguisorba officinalis Linne alleviates atopic dermatitis symptoms by reducing levels of immunoglobulin E and pro-inflammatory cytokines in NC/Nga mice.

Atopic dermatitis is a chronic inflammatory skin disease, and salt-processed Phellodendron amurense (CPE) and Sanguisorba officinalis Linne (SOE) are widely used as anti-inflammatory agents in Asia. Therefore, the present study investigated the efficacy of CPE, SOE, and CPE+SOE in the treatment of atopic dermatitis-like symptoms in mice. Following topical application of 1,3‑butylen glycol (control), 30% CPE, 30% SOE, 15% CPE+15% SOE or 0.1% hydrocortisone (HC) on the atopic dermatitis‑like skin lesions of 2,4-dinitrochlorobenzene‑treated NC/Nga mice for 5 weeks, the severity of clinical atopic dermatitis, mast cell infiltration, serum expression levels of immunoglobulin (Ig)E, IgG1, interleukin (IL)-4 and interferon (IFN)-γ, and cytokine expression in the dorsal skin were measured. Compared with the control group, treatment with CPE alleviated the clinical severity of the AD symptoms, with decreased numbers of mast cells, decreased expression levels of serum tumor necrosis factor (TNF)‑α, IL‑4 and IFN‑γ, and decreased expression levels of inflammatory cytokines in the dorsal lesions. Treatment with SOE did not reduce these expression levels, however, the serum expression levels of IgE and IgG1 were suppressed to similar levels as those in the CPE group. Furthermore, synergistic treatment with CPE and SOE relieved the clinical severity of atopic dermatitis, reduced the serum expression levels of IgE, IgG1, TNF‑α, IL‑4 and IFN‑γ, and suppressed the mRNA expression levels of TNF‑α, IL‑4, IL‑13, and IFN‑γ in the dorsal skin lesions. Treatment with CPE+SOE was superior to treatment with HC alone for reducing dermal thickness and suppressing the production of several cytokines. Therefore, combined treatment with CPE and SOE may be an effective alternative intervention for the management of atopic dermatitis.