LL-37 Inhibited The Secretion Of Inflammatory Cytokines In Mycobacterium Tuberculosis Infected Macrophages

Objective:To research the anti-inflammatory effect of LL-37 in mycobacterium tuberculosis(Mtb)infected-macrophages,as well as its influence on the secretion of inflammatory cytokines.Methods:(1)THP-1 cells were cultured and incubated with phorbol 12-myristate 13-acetate(PMA)to transform into an adherent macrophage-like state(macrophage,M?).Then the THP-1 cell derived macrophages were infected with mycobacterium tuberculosis,and then stimulated with different concentrations of LL-37.(2)The experiment was divided into following groups:(1)Control group: THP-1+normal saline(NS);(2)Mtb group: THP-1+Mtb;(3)Mtb+5 ?g/ml LL-37 group: THP-1+Mtb+5 ?g/ml LL-37;(4)Mtb+10 ?g/ml LL-37 group: THP-1+Mtb+10 ?g/ml LL-37;(5)Mtb+20 ?g/ml LL-37 group: THP-1+Mtb+20 ?g/ml LL-37.(3)The mRNA expression levels of IL-12p40,TNF-?,IL-4,and IL-10 will be determined by Real-time PCR respectively at 6,12,24,and 48 hours.The secreted levels of IL-12p40,TNF-?,IL-4,and IL-10 will be determined by ELISA analysis respectively at 6,12,24,and 48 hours.Results:The mRNA expression levels and secreted levels of IL-12p40,TNF-?,IL-4,and IL-10 were increased in Mtb group than those in control group.The mRNA expression levels and secreted levels of pro-inflammatory cytokines IL-12p40 and TNF-? were decreased in the LL-37 groups than those in Mtb group.However,anti-inflammatory cytokines IL-4 and IL-10 mRNA expression levels and secreted levels were increased in the LL-37 groups than those in Mtb group.Conclusion:Exogenous LL-37 inhibited the secretion of inflammatory cytokines in macrophages during mycobacterium tuberculosis infection.The effect is related to the concentrations of LL-37 and the stimulated time of macrophages which were infected with mycobacterium tuberculosis.The results will provide new insights into the treatment of Mtb infection.