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

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