肠型脂肪酸结合蛋白在严重烧伤小鼠早期肠屏障功能损害评估中的意义

Significance of intestinal fatty acid binding protein in evaluation of intestinal barrier dysfunction of mice at early stage of severe burn injury

目的探讨肠型脂肪酸结合蛋白(IFABP)在严重烧伤小鼠早期肠屏障功能损害评估中的意义。方法取36只雄性8周龄C57BL/6小鼠,按随机数字表法分为正常对照组6只及烫伤组30只。将烫伤组小鼠背部置于90℃热水中10s造成30%体表总面积Ⅲ度烫伤(以下称烧伤),正常对照组小鼠不致伤。取正常对照组6只小鼠并于伤后1、2、6、12、24h分别取6只烫伤组小鼠,取门静脉血,分离血浆,用异硫氰酸荧光素-葡聚糖荧光探针示踪法检测肠道通透性,酶联免疫吸附测定法检测血浆IFABP含量。取正常对照组和烫伤组小鼠伤后各时间点回肠末段组织,苏木精-伊红染色后观察肠黏膜组织形态。对数据行单因素方差分析、SNK检验,采用Pearson相关性检验分析烧伤小鼠肠道通透性与血浆IFABP含量之间的相关性。结果(1)伤后1、2、6、12、24h,烫伤组小鼠肠道通透性分别为2.7±0.8、5.4±2.5、7.3±4.2、12.4±6.1、1.4±0.7,明显高于正常对照组的1.0±0.4(P<0.05或P<0.01)。烫伤组小鼠伤后肠道通透性呈升高趋势,并于伤后12h达高峰,而伤后24h快速回落。(2)伤后1、2、6、12、24h,烫伤组小鼠血浆IFABP的含量分别为(64±11)、(59±12)、(76±18)、(111±22)、(66±10)ng/mL,明显高于正常对照组的(35±8)ng/mL,P<0.05或P<0.01。烫伤组小鼠伤后血浆IFABP的含量呈升高趋势,并于伤后12h达高峰,而伤后24h快速下降。(3)正常对照组小鼠回肠黏膜厚度均匀,上皮层完整,绒毛排列规则,无炎性细胞浸润。烫伤组小鼠伤后1、2h回肠黏膜绒毛不同程度变短,固有层水肿,有中性粒细胞浸润;伤后6、12h回肠黏膜损伤明显,黏膜部分脱落,绒毛排列紊乱、有断裂,上皮细胞有变性、坏死,中央乳糜管扩张,淋巴细胞及中性粒细胞浸润;伤后24h回肠黏膜损伤有所减轻,上皮基本完整,可见中央乳糜管扩张,仍有炎性细胞浸润。(4)烧伤小鼠肠道通透性与血浆IFABP含量呈显著正相关(r=0.841,P<0.05)。结论血浆IFABP可作为评估严重烧伤小鼠早期肠屏障功能损害的较佳生物学指标。

Objective To investigate the significance of intestinal fatty acid binding protein(IFABP)in the evaluation of intestinal barrier dysfunction of mice at the early stage of severe burn injury.Methods Thirty-six 8-week-old C57BL/6 male mice were collected and divided into normal control group(n=6)and scald group(n=30)according to random number table.Back of each mouse in scald group was placed into hot water of 90℃for 10 s,causing full-thickness scald(hereinafter refer to as burn)of 30%total body surface area,while mice in normal control group were not inflicted with burns.Six mice in normal control group were taken,and 6 mice in scald group at 1,2,6,12,and 24 h post injury were taken respectively.The portal vein blood of each mouse was extracted and the plasma was separated to measure intestinal permeability with fluorescin isothiocyanate-dextran fluorescence probe tracing method and plasma IFABP content by enzyme-linked immunosorbent assay.The distal ileum tissue of mice in normal control group and scald group at each time point post injury was collected to observe the morphology of the intestinal mucosa tissue by hematoxylin-eosin staining.Data were processed with one-way analysis of variance and Student-Newman-Keuls test,and pearson correlation test was used to analyze the correlation between intestinal permeability and plasma IFABP content of burned mice.Results(1)At 1,2,6,12,and 24 h post injury,the intestinal permeability of mice in scald group was 2.7±0.8,5.4±2.5,7.3±4.2,12.4±6.1,1.4±0.7,respectively,obviously higher than 1.0±0.4 of normal control group(P<0.05 or P<0.01).The intestinal permeability of mice in scald group showed an increasing trend post injury,reaching the peak at 12 h post injury,and rapidly falling back at 24 h post injury.(2)At 1,2,6,12,and 24 h post injury,the plasma IFABP content of mice in scald group was(64±11),(59±12),(76±18),(111±22),and(66±10)ng/mL,obviously higher than(35±8)ng/mL in normal control group(P<0.05 or P<0.01).The plasma IFABP content of mice in scald group showed an increasing trend post injury,reaching the peak at 12 h post injury,and rapidly decreasing at 24 h post injury.(3)Uniform thickness of mucosa,intact epithelia,regularly arranged villi,and no inflammatory cell infiltration were observed in ileum of mice in normal control group.In ileum of mice in scald group,shortened villi of mucosa with different degrees,edema of lamina propria,and infiltration of neutrophils were observed at 1 and 2 h post injury;obviously damaged and partially exfoliated ileal mucosa,disorderly arranged and broken villi,degenerated and necrotic epithelial cells,dilated central lacteal,and infiltration of lymphocytes and neutrophils were observed at 6 and 12 h post injury;the damage of ileal mucosa was alleviated,and basically intact epithelia,dilated central lacteal,and infiltration of inflammatory cells were observed at 24 h post injury.(4)There was a significantly positive correlation between the intestinal permeability and the plasma IFABP content of burned mice(r=0.841,P<0.05).Conclusions The plasma IFABP can be used as a good biological indicator for the evaluation of intestinal barrier dysfunction of mice at the early stage of severe burn injury.