Optimization of cytokine milieu to reproduce atopic dermatitis-related gene expression in HaCaT keratinocyte cell line

Although atopic dermatitis (AD) is characterized by cytokine production predominantly mediated by T helper (Th) 2 cells, AD pathogenesis also involves innate immune and Th1 cells. To optimize the cytokine milieu required for accurate reproduction of AD-related gene expression profile in vitro, we evaluated the expression pattern of CCL22, CCL17, IL5, IL13, IL33, IL25, TSLP, FLG, and LOR in human lesional AD skin and cytokine-stimulated HaCaT cells. An increase in Th2 mediators (IL5, IL13, CCL22, CCL17, IL25, IL33, and TSLP) and a decrease in genes related to cornified cell envelope (filaggrin and loricrin) were observed in human AD lesions. Innate (tumor necrosis factor-α) and/or Th1/Th2 adaptive cytokines (interferon-γ/IL-4) were required for inducing these inflammatory changes in HaCaT cells, implying that a complex network of innate, Th1, and Th2 cytokines drives AD-like changes. Therefore, stimulation with various combinations of cytokines, beyond Th2 polarization, is necessary when HaCaT cell line is used to study genetic changes implicated in AD pathogenesis.