Role Of TLR9 In UVB Induced HaCaT Cell Photoaging Model

Objective:To explore the molecular mechanism of Toll-like receptor(TLR9)in UVB-induced photoaging model of HaCaT cell.Methods: To This experiment contains three groups: control group,model group,A151 group.The control group was given sham irradiation.The model group was established by the dose of 30 m J/cm2 UVB irradiation.The A151 group was given the dose of 30 mJ/cm2 UVB irradiation and treated with TLR9 inhibitor.The cell senescence was evaluated by aging related beta-galactosidase cytochemistry staining.The cell proliferation rate was measured by CCK-8 assay.The contents of TLR9 and phosphorylation nuclear factor-κB(pNF-κB)were detected by Western blot.The m RNA expression of tumor necrosis factor-α(TNF-α)and interleukin-6(IL-6)were detected by RT-PCR.Results: The protein expressions of TLR9 and pNF-κB were higher in model group than control group(P=0.000,P=0.000),which were attenuated by the A151 treatment(P=0.010,P=0.000).The mRNA levels of TNF-α 、 IL-6 increased in model group compared to control group(P=0.000,P=0.000),which were ameliorated by the A151 treatment(P=0.000,P=0.030).The number of positive cells in aging related beta galactosidase staining was increased in model group compared to control group(P=0.000),while the number of positive cells was decreased in A151 group compared to model group(P=0.000).The cell proliferation rate of model group decreased markedly as compared to control group(P=0.010),while the cell proliferation rate increased in A151 group as compared to model group(P=0.045).Conclusion:The decrease of UVB-induced HaCaT cell proliferation rate and senescence are mediated by phosphorylated NF-κB and elevated mRNA of TNF-α and IL-6 via activation of the TLR9.