Abstract: Objective　We established a deep second-degree scald injury model and model with probiotics and Pseudomonas aeruginosa infection with germ-free rats. Then we compared the differences between the four groups in terms of healing process, inflammatory response, and pathological changes and studied the effect of probiotics on scald healing and burn infection in germ-free rats.Methods　Fifty-six germ-free male Wistar rats weighing 180-200 g were enrolled.The experiment was divided into four groups: sterile group (Group A), probiotic-colonized group (Group B), Pseudomonas aeruginosa-colonized group (Group C), and Pseudomonas aeruginosa plus probiotic co-colonized group (Group D).A 5-cm-diameter deep second degree scald wound was created on the dorsal skin of rats.The scab dislocation time and healing time of the rats were observed, and serum samples were taken to detect the changes of inflammatory cytokines such as GM-CSF and TNF-α. The skin and cecum were fixed in 4% formaldehyde solution and used for histopathology at 14 days after scald.Results　Compared with probiotic-colonized , the aseptic scald rats had a longer period of healing time with significant differences (P<0.05); compared with probiotics stained only rats, the aseptic scald rats have higher serum level of TNF-α and lower serum level of GM-CSF after 24 hours,72 hours, 7 days,14 days, 21 days and 28 days of scalding. And there was a significant difference (P<0.05). Compared with pseudomonas aeruginosa stained only rats, the pseudomonas aeruginosa and probiotic-colonized rats have lower serum level of TNF-α and higher serum level of GM-CSF until 28 days of scalding. After 14 days of scalding, the scalding skin from probiotics stained only rats have mild inflammatory cell infiltration, the scalding skin from the aseptic scald rats and pseudomonas aeruginosa stained only rats had severe inflammatory cell infiltration and the scalding skin from the pseudomonas aeruginosa and probiotics stained rats had moderate inflammatory cell infiltration. After 14 days of scalding, the cecum from probiotics stained only rats had no obvious abnormalities. the cecum from the aseptic scald rats had mild ulcer and mild inflammatory cell infiltration, the cecum from pseudomonas aeruginosa and probiotic-colonized rats had severe ulcer and severe inflammatory cell infiltration, the cecum from pseudomonas aeruginosa and probiatics stained only rats had mild ulcer and moderate inflammatory cell infiltration. Conclusions　Probiotics can enhance body’s immunity after scalding and reduce inflammatory response. Probiotics are beneficial for the repair of intestinal mucosa and burn wounds.

Key words: probiotics, germ-free rat, burn, Pseudomonas aeruginosa, GM-CSF, TNF-α

摘要： 目的　采用无菌大鼠建立深二度烧伤模型并分别定植益生菌和绿脓假单胞菌,观察大鼠在愈合过程、炎性反 应及病理变化等方面的差异,探讨益生菌对无菌大鼠烧伤及烧伤感染后愈合作用的影响。方法　选用无菌Wistar 大鼠56只,体质量180~200 g,雄性,实验分为4组:无菌组(A组)、定植益生菌组(B组)、定植绿脓假单胞菌组(C 组)和定植绿脓假单胞菌和益生菌组(D组)。建立背部直径5 cm的圆形深二度烧伤模型,分时段取材,比较4组 大鼠血清TNF-α、GM-CSF水平的差异,HE染色盲肠及伤口处皮肤组织,观察伤口愈合情况。结果　定植益生菌组 伤口愈合时间显著少于无菌组(P<0.05),血清TNF-α水平在烧伤24 h、72 h、7 d、14 d、28 d时,显著低于无菌烧伤 组,血清GM-CSF水平显著高于无菌烧伤组(P<0.05);定植益生菌绿脓假单胞菌组在烧伤后至28 d,血清TNF-α水 平显著低于定植绿脓假单胞菌组(P<0.05),血清GM-CSF水平显著高于定植绿脓假单胞菌组(P<0.05)。烧伤 14 d,烧伤处皮肤组织HE显示,定植益生菌组轻度炎性细胞浸润;无菌组和定植绿脓假单胞菌组重度炎性细胞浸 润;定植益生菌和绿脓假单胞菌组中度炎性细胞浸润。烧伤后14 d,盲肠组织HE染色显示,定植益生菌组未见明 显异常;无菌组轻度溃疡,轻度炎性细胞浸润;定植绿脓假单胞菌组重度溃疡,重度炎性细胞浸润;定植益生菌和绿 脓假单胞菌组大鼠轻度溃疡,中度炎性细胞浸润。结论　益生菌能够提高烧伤后机体的自身免疫力,降低炎性反 应,有利于肠道黏膜和创面的修复。

关键词: 益生菌, 无菌大鼠, 烧伤, 绿脓假单胞菌, GM-CSF, TNF-α