Abstract: Wang Yuanyuan, Hu Mingjie, Zhang Jing, Huang Yinjiu, Tang Bikui, Chen Changjie, Wu Shouwei. Department of Biological Sciences, Bengbu Medical College, Bengbu 233030, Anhui, China Corresponding author: Wu Shouwei, Email: nlicau@126.com 【Abstract】 Objective To investigate the effect of lidocaine on Staphylococcus aureus exotoxin-stimulated peripheral blood mononuclear cells （PBMCs） from patients with atopic dermatitis （AD）. Methods Peripheral blood samples were collected from 6 patients with AD, and PBMCs were isolated by a routine method. Then, the PBMCs were stimulated by the Staphylococcus aureus exotoxin toxic shock syndrome toxin-1 （TSST-1） in the absence or presence of lidocaine at varying concentrations. The 3H-TdR incorporation method was performed to detect the proliferation of monocytes, and enzyme-linked immunosorbent assay （ELISA） to quantify the levels of T helper type 1 （Th1） and Th2 cytokines released by PBMCs. Human HaCaT keratinocytes were co-cultured with lidocaine- and TSST-1-stimulated PBMCs from patients with AD for 72 hours, then, Western blot was conducted to examine the expression of filaggrin protein in HaCaT cells. Results TSST-1 （100 μg/L） significantly enhanced the proliferation of PBMCs from patients with AD （stimulation index = 75 ± 2.12, P < 0.05）, as well as the release of tumor necrosis factor-α （TNF-α）, interferon （IFN）-γ, interleukin （IL）-2, IL-12, IL-4, IL-5 and IL-13 by the PBMCs （all P < 0.05）. Compared with the blank control group, 100 μmol/L lidocaine significantly inhibited the TSST-1-stimulated proliferation of PBMCs from patients with AD （stimulation index = 58 ± 3.14, P < 0.05）, as well as the release of IL-4, IL-5, IL-13, TNF-α and IFN-γ by the stimulated PBMCs （all P < 0.05）. Western blot showed that 100 μmol/L lidocaine significantly blocked the down-regulation of filaggrin expression in HaCaT cells （P < 0.01）. Conclusion Lidocaine has a significant inhibitory effect on the activation of TSST-1-stimulated PBMCs from patients with AD.

Key words: Atopic dermatitis, Staphylococcus aureus, Exotoxins, Lidocaine, Monocytes