The role of bifidobacteria in gut barrier function after thermal injury in rats.
BACKGROUND
Early multiple organ dysfunction syndrome appears to be facilitated with bacterial translocation in severe burn injury, yet the mechanisms of bacterial translocation remain in dispute. The aim of this study was to characterize the potential role of intestinal bifidobacteria in the pathogenesis of gut-derived bacterial translocation after burns and to analyze the effects of bifidobacterial supplement on gut barrier function.


METHODS
Wistar rats were randomly divided into burn group (Burn, n = 60), sham burn group (SB, n = 10) in experiment 1, and burn + saline group (BS, n = 30), burn + bifidobacteria group (BB, n = 30), and sham-burn + saline group (SS, n = 30) in experiment 2. Animals in BB group were fed bifidobacterial preparation (5 x 10(9) CFU/mL) after burns, 1.5 mL, twice daily. Animals in BS and SS were fed saline. Samples were taken on postburn days 1, 3, and 5. The incidence of bacterial translocation and counts of Bifidobacterium, fungi and Escherichia coli in gut mucosa, as well as the sIgA levels in mucus of the small intestine were determined. The positive sIgA expression in lamina propria and ileum mucosal injury were evaluated light microscopically by blinded examiners.


RESULTS
The incidence of bacterial translocation was increased after burns, which was accompanied by significant decrease in number of bifidobacteria but significant increase in E. coli and fungi in gut mucosa, and elevation of levels of plasma endotoxin and IL-6 (p < 0.001). The incidence of bacterial translocation was markedly reduced after 3- and 5-day supplementation of bifidobacteria compared with control group (p < 0.05). The counts of mucosal bifidobacteria were increased by 4- to 40-fold, whereas E. coli and fungi were decreased by 2- to 30-fold and 10- to 150-fold, respectively, after bifidobacterial supplementation. The damage of mucosa tended to be less pronounced after 3-day bifidobacteria-supplemented formula compared with control group (grade 2 [0-6] versus grade 4 [3-6], p < 0.05). Moreover, the expression and release of sIgA was markedly augmented after 3-days of bifidobacteria-supplementation formula and it returned to normal range on postburn day 5.


CONCLUSIONS
The decrease in counts and proportion of bifidobacteria to other flora in gut may play an important role in the development of bacterial translocation after thermal injury. Supplementation of exogenous bifidobacteria could improve gut barrier function, and attenuate bacterial/endotoxin translocation secondary to major burns.
Wang
Zhongtang
Z
Center of Plastic Surgery, Xijing Hospital, Fourth Military Medical University, Xi'an, China. wangkingking@hotmail.com
Xiao
Guangxia
G
Yao
Yongming
Y
Guo
Shuzhong
S
Lu
Kaihua
K
Sheng
Zhiyong
Z
D000821:Animal Feed / Q000382:microbiology; D000818:Animals; D018988:Bacterial Translocation / Q000502:physiology*; D001644:Bifidobacterium / Q000302:isolation & purification / Q000502:physiology*; D002056:Burns / Q000097:blood / Q000382:microbiology* / Q000503:physiopathology; D015169:Colony Count, Microbial; D004731:Endotoxins / Q000097:blood; D004926:Escherichia coli / Q000302:isolation & purification; D005260:Female; D005658:Fungi / Q000302:isolation & purification; D007082:Ileum / Q000382:microbiology* / Q000503:physiopathology; D007071:Immunoglobulin A, Secretory / Q000378:metabolism; D015850:Interleukin-6 / Q000097:blood; D007413:Intestinal Mucosa / Q000382:microbiology* / Q000503:physiopathology; D008297:Male; D051381:Rats; D017208:Rats, Wistar
D004731:Endotoxins; D007071:Immunoglobulin A, Secretory; D015850:Interleukin-6