The role of inflammatory release from human eosinophils-induced by the antimicrobial peptide LL-37 in the pathogenesis of asthma / 医学研究生学报

ABSTRACT

Objective The antimicrobial peptide LL-37 ( LL-37) is the mature form of Human Cationic Antimicrobial Pep-tide of 18kD (hCAP18) and play a certain regulation role in the pathogenesis of asthma .However, the mechanism is unclear.The aim of this study was to investigate the role of inflammatory release from human eosinophils induced by the antimicrobial peptide LL -37 in the pathogenesis of asthma and the underlying mechanisms . Methods Sixteen mild or medium allergic asthma patients from January 2015 to January 2016 in Panzhihua college affiliated hospital were enrolled .Another 16 healthy volunteers were enrolled as control .Pri-mary eosinophils were isolated from peripheral blood .The cells were divided into two groupsasthma group and healthy control group . Cells were divided into blank , PAF, LL37, single cytokine ( IL-5, GM-CSF) and cytokines combined with LL-37 group based on in-tervention (cell treating factors) difference;Cells were divided into PTx, WRW4, suramin, and LL-37 combined with inhibitors group based on inhibitors difference;Cells were grouped into LTD 4 and LTB4 treatment based on leukotrienen difference;ELISA was applied to analyze cysteinyl leukotrienes ( cys-LTs) level in various treatment groups;Western blot was used to detect change of cPLA 2, p-cP-LA2, ERK1/2, p-ERK1/2 in the cells from the control group after PTx and WRW 4 treatment and the level of hCAP 18 after leukot-riene treatment. Results Compared with the control 15 μg/mL LL-37 sub group, the expression of Cys-LTs was increased in the control 30μg/mL LL-37 sub group 15 and 30 minutes after the LL-37 treatment [(54.02±7.15) pg/105 vs (37.86±6.33) pg/105, (53.30±6.99) pg/105 vs (36.27±6.46) pg/105, P<0.05].Compared with the control IL-5 sub group (26.18±4.86) pg/105, the ex-pression of Cys-LTs was increased in the control IL-5+15 μg/mL LL-37 sub group (59.97±6.83) pg/105 and the control IL-5+30μg/mL LL-37 sub group (81.44±13.70) pg/105(P<0.05).Compared with the control sub group , the expression of Cys-LTs was in-creased in the asthma 15 μg/mL LL-37 sub group and the asthma 30μg/mL LL-37 sub group ( P<0.05) .Compared with the control LL-37 sub group, the expression of Cys-LTs was decreased in the control PTx sub group , control WRW4 sub group, control suramin sub group, control PTx +LL-37 sub group, and control WRW4+LL-37 sub group (P<0.05).Western blot results indicated that LL-37 treatment induced the activation and phosphorylation of ERK 1/2 in eosinophil, and PTx and WRW4 blocked the upregulation of pERK1/2 induced by LL-37.Treatment with PD inhibited the phosphorylation of cPLA 2 and the release of Cys-LTs induced by LL-37. hCAP18 was higher in the asthma groups than the healthy control . Conclusion LL-37 was identified as an eosinophil-activating pep-tide that could trigger the release of inflammatory mediators , which might be involved in occurrence and development of asthma through regulating ERK1/2 phosphorylation, inducing cPLA2 phosphorylation and finally initiate synthesis of cys-LTs.This suggests that LL-37/hCAP18 and its signaling pathway might be potential therapeutic targets for asthma .