LL-37 inhibited secretion of inflammatory cytokines in mycobacterium tuber-culosis infected macrophages / 中国免疫学杂志

ABSTRACT

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,Mφ). 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 groupTHP-1+normal saline (NS);② Mtb groupTHP-1+Mtb;③Mtb+LL-37 5 μg/ml groupTHP-1+Mtb+5 μg/ml LL-37;④Mtb+LL-37 10 μg/ml groupTHP-1+Mtb+10 μg/ml LL-37;⑤Mtb+LL-37 20 μg/ml groupTHP-1+Mtb+20 μg/ml LL-37. (3) The mRNA expression levels of IL-12p40,TNF-α,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-α,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-α,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-α 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 tu-berculosis 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.