Evidence of regulatory myeloid dendritic cells and circulating inflammatory epidermal dendritic cells-like modulated by Toll-like receptors 2 and 7/8 in adults with atopic dermatitis

Abstract Backgroud Atopic dermatitis ( AD ) is a chronic, inflammatory skin disease characterized by intense pruritus and xerosis. Dendritic cells ( DC ) play an essential role in tissue inflammation in atopic dermatitis ( AD ) skin, especially the inflammatory epidermal dendritic cells ( IDEC ), a particular subset of myeloid dendritic cells ( mDC ). The aim of the present study was to assess the phenotype and function of mDC and circulating IDEC ‐like in peripheral blood mononuclear cells ( PBMC ) of adults with AD. Methods We selected 21 AD patients and 21 non‐ AD controls, age and gender matched. Expressions of Fc ε RI , CD 36, TNF , IFN ‐ γ , and IL ‐10 in mDC were analyzed by flow cytometry under various stimuli, such as staphylococcal enterotoxin B ( SEB ), TLR 2 (Pam3 CSK 4), TLR 4 ( LPS ), and TLR 7/8 ( CL 097) agonists. Results The most prominent findings in AD patients were: (i) enhanced frequency of IL ‐10 under TLR 4 ( LPS ), and decreased frequency of IFN ‐ γ and TNF under TLR 2 (Pam3 CSK 4) and 7/8 ( CL 097) stimulation in classic mDC ; (ii) elevation of circulating IDEC ‐like frequency with TLR 2 (Pam3 CSK 4) stimuli, augmented frequency of IFN ‐ γ in nonstimulated condition , and of IL ‐10 under TLR 7/8 ( CL 097) stimuli in IDEC ‐like population. Conclusions In AD individuals, classic mDC showed an immunomodulatory profile, favoring tolerance in a combined action with IDEC ‐like, and inducing Th1 polarization. Our findings indicate a potential role of IDEC ‐like in the maintenance of inflammation in atopic dermatitis patients; moreover, IDEC ‐like may exert a regulatory impact on T cells of AD individuals through IL ‐10, often induced by agonist mimicking single stranded RNA virus.