补充双歧杆菌可促进烫伤大鼠肠道sIgA合成与分泌

Bifidobacterial supplement enhances the expression and excretion of intestinal sIgA in severely burned rats

目的:探讨严重烫伤后补充双歧杆菌与肠道 sIgA 合成、分泌的关系。方法:Wistar 大鼠70只随机分为烫伤对照组(BC,n=30)、烫伤治疗组(BT,n=30)、假伤组(NC,n=10)。BT 组伤后灌胃双歧杆菌悬液(5×10~9 cfu/ml),1.5ml,2/d。检测大鼠细菌及内毒素移位、膜菌群中双歧杆菌量、肠粘液 sIgA 浓度及肠道浆细胞sIgA 表达情况等。结果:(1)伤后3d,BC 组与 BT 组细菌移位率分别为42%和16%(P=0.004),伤后5d 分别为30%和8%(P=0.002)。(2)伤后大鼠盲肠膜菌群中双歧杆菌减少约10～60倍;灌胃双歧杆菌悬液后肠道双歧杆菌明显增多。(3)BC 组肠粘液 sIgA 平均减少约30%,伤后3d 达最低;BT 组3d 伤后基本恢复正常。伤后回肠粘膜下固有层浆细胞 sIgA 表达减弱,补充双歧杆菌后 sIgA 表达显著增强,5d 接近 NC 组。(4)膜菌群中双歧杆菌量与肠粘液 sIgA 浓度呈显著正相关。结论:严重烫伤后肠道 sIgA 产生明显受抑制,其改变与膜菌群中双歧杆菌减少有关,补充外源性双歧杆菌可促进肠道 sIgA 合成与分泌。

Objective;To investigate the potential effect of bifidobacterial supplement on intestinal mucosal im- munity associated with severe burns.Methods;Wistar rats were randomly divided into burn control group (BC,n =30),treatment group (BT,n=30),and sham-burn group (NC,n=10).Rats in BT group were fed bifidobac- terial preparation (5×10~9cfu/ml) after 30% total body surface area full-thickness burns,1.5ml,twice daily.Rats in BC and NC were fed normal saline,1.5ml,twice daily.Samples were taken on postburn days 1,3,and 5.The incidence of with standard methods.The sIgA levels in mucus of small intestine were measured by RIA.The posi- tive sIgA expression in lamina propria was detected by immunohistochemical staining.Results;(1) The incidence of bacterial translocation were 42% and 16% in BC group and BT on postburn day 3 (P=0.004),30% and 8% on day 5 (P=0.002),respectively.Plasma endotoxin levels were markedly higher in BC and BT groups than 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=0.0412).(2) The bifidobacteria counts in cecum mucosa were reduced by 10-to 60-fold after thermal injury,while there was a remarkable increase in bifidobacteria counts in animals fed with bifidobacte- ria.(3) The sIgA levels in intestinal mucus were significantly decreased in group BC,but they returned to normal range in BT group on postburn day 5.Similarly,sIgA expression in lamina propria was also weakened after burns,it had a tendency to recovery after 5-day bifidobacteria-supplemented formula.(4) There was a strong pos- itive correlation between the counts of bifidobaeteria in cecal mucosa and the levels of sIgA in intestinal mucus (r= 0.7534,P=0.0000).Conclusions;The expression and excretion of sIgA in intestine appears to be markedly in- hibited following a severe thermal injury.The supplement of exogenous bifidobacteria could improve sIgA forma- tion in small intestine,thereby reducing the incidence of bacterial/endotoxin translocation secondary to major burns.