Objective To study the effect of selective COX-2 inhibitor NS398 on IL-10 and IFN-γexpression in human keratinocytes induced by UVA,and further to explore the effect on anti human skin photoaging.Methods HaCaT cells were divided into three groups:simple UV exposure group,NS398-intervene group and blank group.For UV radiation,simple UV exposure group and NS398-intervene group were irradiated with UVA at a dose of 30 J/cm2.In order to assess the effect of NS398,HaCat cells were treated with NS398 at the dose of 0,20,40,80μmol/L respectively and then incubated without irradiation for 2h,substrate changed and cultured for 24h,and then the expression of IL-10 and IFN-γ mRNA was detected via RT-PCR.Results Simple UV exposure group had obviously higher expression of IL-10 mRNA and lower expression of IFN-γ mRNA than that of control group,while NS398-intervened group had significantly lower expression of IL-10 mRNA and higher expression of IFN-γ mRNA than that of simple UV exposure group,and dose-dependency existed.Conclusions NS398 may delay photo-damage of human skin via inhibiting the expression of IL-10 mRNA and up-regulating the expression of IFN-γ mRNA in human keractinocytes.