The development of atopic dermatitis (AD) involves multiple factors. Three such factors are particularly important in AD onset: immune abnormalities, skin barrier dysfunction, and itching. Many studies report that an imbalance between helper T (Th)1 and Th2 cells causes AD. Apple pectin, a prebiotic, has preventative effects in other allergic diseases (e.g., bronchial asthma and AD), but its potential benefits in AD are unclear. In this study, we investigated the effect of oral apple pectin administration on skin inflammation in an AD mouse model and examined changes in T cells involved in AD. To induce AD, a picryl chloride solution was applied to the shaved back skin of male NC/Nga mice. AD mice then received an oral apple pectin solution (0.4% or 4%) for 35 d. Compared with untreated AD mice, mice in both apple pectin-treated groups showed improvement in AD-induced inflammation and skin symptoms. Histological evaluation showed that apple pectin treatment attenuated epidermal thickening and decreased the number of mast cells and CD4+ cells in AD-induced mice. Apple pectin treatment also reduced serum IgE concentration, as well as expression of the inflammation indicator cyclooxygenase-2 and the Th2-related factors thymic stromal lymphopoietin, interleukin-4, and GATA3. Additionally, increased mRNA expression of the genes that encode interferon-γ and T-bet, which are Th1-related factors, and forkhead box protein P3, were observed in the apple pectin-treated groups. Our findings suggest that apple pectin treatment ameliorates AD by increasing regulatory T cells and improving the Th1/Th2 balance in the skin of AD model mice.
Keywords: Foxp3; Th1/Th2 balance; apple pectin; atopic dermatitis; prebiotics.