Effects of azelaic acid and salicylic acid on the level of inflammatory factors and TLR4 protein induced by Propionibacterium acnes
Objective To investigate the effects of azelaic acid and salicylic acid on the expression of inflammatory factors and Toll-like receptor4(TLR4)induced by Propionibacterium acnes.Methods The effect of drugs on cell proliferation was detected by CCK-8 method.The concentrations of interleukin(IL)-8,IL-1β and tumor necrosis factor-α(TNF-α)in the supernatant of cell culture were detected by enzyme linked immunosorbent assay(ELISA).The molecular interaction of azelaic acid,salicylic acid and TLR4 protein receptor was analyzed by molecular docking.The expression of TLR4 protein on the surface of HaCaT cells was verified by cellular immunofluorescence and fluorescence intensity analysis.Results After treated with azelaic acid or salicylic acid for 48 h,the safe concentrations of azelaic acid and salicylic acid in HaCaT cells were 62.50 μg/mL and 31.25 μg/mL,respectively.The maximum experimental mass concentration of azelaic acid and salicylic acid in THP-1 cells were 1 000.00 μg/mL and 500.00 μg/mL,respectively.Azelaic acid and salicylic acid inhibited IL-8 production in HaCaT cells induced by P.acnes cell wall component peptidoglycan(PGN)+ lipoteichoic acid(LTA)or heat inactivated P.acnes.Furthermore,azelaic acid and salicylic acid could also inhibit IL-1β and TNF-α production in THP-1 cells induced by phorbol ester(PMA)+ lipopolysaccharide(LPS)or heat inactivated P.acnes in a dose-dependent manner.Molecular docking showed that azelaic acid and salicylic acid could bind to TLR4 protein receptor effectively.Compared with the control group,the fluorescence intensity of TLR4 on the surface of HaCaT cells stimulated by PGN + LTA or heat inactivated P.acnes was significantly increased(P<0.01).After treated with 62.50 μg/mL azelaic acid,the expression of TLR4 protein on the surface of HaCaT cells was significantly decreased(P<0.01).Meanwhile,pretreatment with 31.25 μg/mL salicylic acid could significantly reduce the expression of TLR4 protein on the surface of HaCaT cells induced by heat inactivated P.acnes(P<0.05).Conclusion Azelaic acid and salicylic acid can inhibit the production of pro-inflammatory factors in keratinocytes and mononuclear macrophages induced by P.acnes,and also reduce the expression of TLR4 protein on the surface of keratinocytes.Thus,azelaic acid and salicylic acid all play an important role in the treatment of acne.
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