Abstract: Objective: To determine the effects of exosomes in peripheral blood of patients with atopic dermatitis (AD) on the activation and inflammation of keratinocytes. Methods: The peripheral blood samples of 30 AD patients and 30 healthy volunteers were collected and exosomes were isolated from plasma. The normal human exosomes of protein concentration 0 g/L, 20 g/L, 40 g/L and 80 g/L were respectively co-cultured with normal keratinocytes cell line HaCaT. The proliferation of cells in each group was detected by CCK-8, and the apoptosis of cells was detected by Annexin V-FITC/PI double staining method to ensure the optimum concentration of exosomes. The exosomes with optimum concentration was co-cultured with keratinocytes cell line HaCaT of the AD patients. The markers of activation (K16), differentiation (K10, IVL) and inflammation (TSLP, IL-25, IL-33, CXCL1, CXCL2) in the AD exosomes group, normal human exosomes group and blank control group were detected by fluorescence quantitative-PCR. Results: Compared with other concentrations of exosome, the proliferation rate of HaCaT cells in 40 g/L gruop was the lowest and the apoptotic rate was highest. The optimum concentration of exosomes was 40 g/L. The expression levels of K16，K10，IVL，TSLP， IL-25，IL-33， CXCL2 in the AD exosomes group were higher than those in the blank control group and normal human exosomes group (P<0.05). However, there was no statistical significance in the expression levels of CXCL1 between the three groups (P＞0.05). Conclusion: Exosomes in peripheral blood of the patients with AD may play an role in the development of AD through promoting the activation, differentiation and inflammation of keratinocyte.

Key words: atopic dermatitis, exosomes, keratinocytes