双歧杆菌对烫伤大鼠肠道黏膜机械及生物屏障的改善作用

Improvement of bifidobacterial supplement on the barrier function of intestinal mucosa and microbe flora induced by thermal injury in rats

目的 :探讨严重烫伤后补充外源性双歧杆菌对肠黏膜机械及生物屏障的保护作用及其对肠道细菌或内毒素移位的影响。方法 :70只 Wistar大鼠按随机数字表法分为烫伤对照组 ( BC)、烫伤治疗组 ( BT)和假伤对照组 ( NC)。BT组伤后灌饲双歧杆菌悬液 ( 5× 10 1 2 CFU/ L) 1.5 ml,2次 / d。观察细菌或内毒素移位、肠黏膜菌群和肠黏膜损伤情况等。结果 :1伤后 3 d,BC、BT组细菌移位率分别为 42 %和 16 % ( P=0 .0 0 40 ) ,5 d分别为30 %和 6 % ( P=0 .0 0 2 0 ) ;伤后 1d,BC组内毒素水平显著高于 BT组。 2 BC组回盲部黏膜菌群中双歧杆菌量仅为 NC组的 1/ 10～ 1/ 6 0 ,BT组双歧杆菌量明显增多 ;BC组大肠杆菌量在 1、3 d增加约 2 0～ 30倍 ,但 3 d后BT组大肠杆菌量显著减少并接近正常水平。 3回肠黏膜损伤以 1、3d最为明显 ,BC组伤后 5 d损伤评分仍明显高于 NC组 ( P<0 .0 5 ) ;BT组 3d时已明显修复 ,5 d已与 NC组无明显差异。结论 :补充外源性双歧杆菌能促进烫伤后受损肠黏膜屏障和生物屏障修复 ,有效防治肠道细菌或内毒素移位。

Objective:To investigate the potential effect of bifidobacterial supplement on intestinal mucosal and biological barrier following severe burns.Methods:Seventy Wistar rats were randomly divided into burn control group (BC,n=30),burn + treatment group (BT,n=30),and shamburn group (NC,n=10). Animals in BT group were fed bifidobacterial preparation (5×10 12 CFU/L) after 30% total body surface area(TBSA) fullthickness thermal injury,1 5 ml,twice daily.Samples were taken on postburn days 1,3,and 5 The incidence of bacteria/endotoxin translocation and the counts of bifidobacteria,E.coli,and fungi in ileocecum mucosa were determined with standard methods.Ileum mucosal injuries were evaluated light and electron microscopically by blinded examiners.Results:①The incidence of bacterial translocation were 42% and 16% in BC and BT groups on postburn day 3(P=0 004 0),30% and 6% on day 5 (P=0 002 0), respectively.Plasma endotoxin levels were markedly higher in BC and BT groups than that in NC group at the early stage postburn,while there was a significant decrease in BT group compared with BC group on postburn day 1 (P=0 04).②The bifidobacteria counts in ileocecum mucosa were reduced by 10 to 60fold after thermal injury,while there was a remarkable increase in animals fed with bifidobacteria.The E.coli counts in ileocecum mucosa were increased by 20 to 30fold on postburn days 1 and 3,whereas those markedly reduced after 3day bifidobacteriasupplemented formula,tending to normal range.③There were obviously ileum mucosal lesions on postburn days 1 and 3,the ileum lesion scores remained significant higher in BC group than that in NC group on postburn 5 day (P<0 05).However,the damaged ileum mucosa was markedly repaired after 3day bifidobacteriasupplemented formula,and almost restored 5 days later.Conclusion:The intestinal mucosal and biological barrier appear to be markedly damaged after severe burns.The supplement of exogenous bifidobacteria can facilitate the improvement of mucosal as well as biological barrier function, thereby reducing the incidence of bacteria/endotoxin translocation secondary to major burns.