髓系细胞触发受体-1在脐带血白细胞中的表达及其意义

Significance of triggering receptor expressed on myeloid cells-1 of cord blood leukocytes in neonates

目的观察髓系细胞触发受体-1（triggering receptor expressed on myeloidcells-1，TREM-1）在脐带血白细胞膜表达和mRNA转录水平，并分析其促进炎症细胞因子分泌的功能。方法2013年9月至2014年3月，分别收集20例健康足月新生儿出生时的脐带血和20例健康成年人的外周血，采用流式细胞术检测中性粒细胞和单核细胞TREM一1平均荧光强度和TREM一1阳性比例，实时荧光定量逆转录-聚合酶链反应技术检测白细胞TREM-1 mRNA。分别用脂多糖或LP17＋脂多糖刺激脐带血白细胞，用酶联免疫吸附法检测上清液中可溶性TREM-1、肿瘤坏死因子-α（tumornecrosisfactord，TNF-α）、白细胞介素（interleukin，IL）-6、IL-8浓度，并与未经刺激者（空白对照）作比较。采用成组t检验、方差分析、q检验和Pearson相关分析进行统计学分析。结果新生儿脐带血白细胞TREM-1的平均荧光强度与成年人比较，差异无统计学意义（P〉0．05）。新生儿中性粒细胞TREM-1阳性百分率为（82．3±7．1）％，低于成年人的（98．6±4．8）％，差异有统计学意义（t=8．512，P〈0．01）。新生儿TREM-1mRNA水平为1．16±0．13，低于成年人的1．63±0．24，差异有统计学意义（t=7．714，P〈0．01）。新生儿脐带血未经脂多糖刺激，24h后上清液sTREM-1浓度为（34．6±6．1）pg／ml；经脂多糖刺激24h后，上清液sTREM—1浓度上升至（156．7±36．3）pg／ml，差异有统计学意义（f=13．623，P〈0．01）。LP17联合脂多糖处理后的脐带血IL-6、TNF-α、IL-8浓度明显低于仅经脂多糖处理的脐带血（P值均〈0．05）。新生儿脐带血经脂多糖刺激24h后，上清液中sTREM-1浓度与TNF-α、IL-6、IL-8浓度呈正相关（r值分别0．519、0．507和0．538，P值分别为0．019、0．022和0．014）。结论新生儿脐带血单核细胞TREM-1发育情况与成年人一致，中性粒细胞TREM-1阳性比例低于成年人。阻断脐带血白细胞TREM-1可部分减少闩细胞炎症细胞因子的分泌。

Objective To investigate the triggering receptor expressed on myeloid cells-1（TREM-1） of cord blood leukocytes in neonates and the transcription level of mRNA, and analyze its promoting function of inflammatory cytokine secretion. Methods During the period from September 2013 to March 2014, cord blood was collected from 20 term neonates at the time of birth, and peripheral blood was collected from 20 healthy adults. The expression of TREM-1 and TREM-1 mRNA on leukocytes was observed using flow cytometry and real-time reverse transeription-polymerase chain reaction, respectively. After the whole cord blood was stimulated by lipopolysaccharide （LPS） or LP 17 plus LPS, the contents of interleukin （IL）-6, tumor necrosis factor-ct （TNF-α）, IL-8 and soluble TREM-1 （sTREM-1） in the supernatant were analyzed by enzyme linked immunosorbent assay. The statistical significance was determined using the one way ANOVA test, t test, q test and Pearson correlation coefficient. Results The mean fluorescence intensity of TREM-1 on leukocytes of newborns was not different compared with healthy adults （P〉0.05）, while the percentage of TREM- 1 positive on polymorphonuclear cells was lower than that of healthy adults [（82.3 ±7.1）% vs （98.6±4.8）%, P〈0.05]. The level of TREM-1 mRNA in newborns was lower than in healthy adults （1.16 ± 0.13 vs 1.63 ± 0.24, t=-7.714, P〈0.01）. The LPS treatment significantly increased sTREM-1 in newborn whole blood compared with the control treatment [（156.7±36.3） vs （34.6±6.1） pg/ml, t=-13.623, P〈0.01]. The concentration of IL 6, TNF- a and IL-8 decreased significantly when TREM-1 was blocked by LP17. In addition, the concentration of sTREM-1 showed a positive correlation with the levels of TNF- α （r=-0.519, P〈0.05）, IL-6 （r=0.507, P〈0.05） and IL-8 （1=0.538, P〈0.05）. Conclusions Healthy newborns exhibit expression of TREM-1 on monocytes similar to healthy adults, and most PMNs express TREM-I at the newborn stage. Blocking the TREM-1 signal transduction pathway may reduce inflammatory responses of neonate leukocytes.