无菌大鼠深二度烫伤感染模型机体炎性反应的研究

为探究无菌大鼠深二度烫伤感染模型机体炎性反应，试验利用无菌大鼠分别建立深二度烫伤损伤模型和烫伤后绿脓杆菌感染模型，比较这两种模型和SPF级大鼠深二度烫伤模型在愈合过程、炎性反应及病理变化等方面的异同。20只6周龄雌性Wistar无菌大鼠，在超净工作台内采用恒温恒压烫伤仪94℃作用8 s造成大鼠深二度烫伤，随机分为2组，一组伤口感染浓度为1×10⁵ CFU/mL绿脓杆菌菌液0.5 mL，一组不做处理，创面保持无菌状态，SPF级Wistar大鼠在同样条件下烫伤，创面不做处理。分别观察3组大鼠的伤口结痂时间、脱痂时间和愈合时间，并在烫伤前（0 h），烫伤后24 h、3 d和7 d时，取血清，检测炎性因子肿瘤坏死因子-α（TNF-α）、白细胞介素1α（IL-1α）、粒细胞-巨噬细胞刺激因子（GM-CSF）的变化。结果显示，感染绿脓杆菌大鼠组开始结痂所需时间显著长于SPF级大鼠组和无菌大鼠组（P<0.05）；而脱痂及愈合所需时间显著变短（P<0.05）；感染绿脓杆菌组大鼠烫伤24 h时，皮下组织中可见淋巴细胞，有慢性炎性反应；3 d时，真皮深层有化脓性感染，横纹肌周围可见大量炎细胞，烫伤7 d时，皮下组织中有轻微血管扩张充血，化脓性感染减轻，无菌烫伤大鼠与SPF级烫伤大鼠皮肤在烫伤后一周内有轻度炎性反应。3组大鼠烫伤后，血清GM-CSF、IL-1α及TNF-α水平均较烫伤前显著升高（P<0.05）；烫伤24 h时，感染绿脓杆菌大鼠组和无菌大鼠组血清IL-1α水平显著高于SPF级大鼠组（P<0.05）；无菌大鼠组血清GM-CSF水平显著高于SPF级大鼠组和感染绿脓杆菌大鼠组（P<0.05）；烫伤3 d时，染绿脓杆菌大鼠组和无菌大鼠组血清IL-1α水平显著高于SPF大鼠组（P<0.05），无菌大鼠组血清GM-CSF水平显著高于染绿脓杆菌大鼠组（P<0.05）。综上所述，无菌大鼠对烫伤刺激反应迅速强烈，血清中炎性因子迅速升高，SPF级大鼠深二度烫伤后炎性反应缓慢；无菌大鼠深二度烫伤伤口感染1×10⁵ CFU/mL绿脓杆菌，脱痂时间和愈合时间反而缩短。

Study on Inflammatory Response of Germ-free Rats with Second Degree Scald

To study the inflammatory response of germ-free rats with deep second-degree scald injury,a deep second-degree scald injury model of germ-free rats which were infected with Pseudomonas aeruginosa and a deep second-degree scald injury model of SPF rats were established,then the similarities and differences between the three groups in terms of healing process,inflammatory response,and pathological changes were compared,and the effect of inflammatory reaction of deep second-degree scald injury sterile rats were explored.Deep second degree scald wound was performed in 20 6-week-old female germ-free rats at the temperature of 94℃,8 s in a clean bench.And then the scald germ-free rats were randomly divided into two groups,one group was infected with Pseudomonas aeruginosa with a concentration of 1×10⁵ CFU/mL in the wound,the other group was not infected and the wound kept clean.SPF scald Wistar rats were set up as control group under the same conditions.The scab escharosis time,dislocation time and healing time of the three groups were observed,and serum samples were taken to detect the changes of inflammatory cytokines such as TNF-α,IL-1α and GM-CSF before burned (0 h) and 24 h,3 d and 7 d after burned.The results showed that the Pseudomonas aeruginosa infection rats had a long period of scab escharosis time (P<0.05) and the decrustation and healing time was significantly short compared with SPF rat and germ-free rats (P<0.05).When the burned rats were infected with Pseudomonas aeruginosa for 24 h,lymphocytes were observed in the subcutaneous tissues and there were chronic inflammatory reactions.At the 3rd day,there was a purulent infection in the deep dermis,and a large number of inflammatory cells were seen around the striated muscle.On the 7th day,there was slight blood vessel dilatation and congestion,and purulent infection was relieved.The skin of germ-free scald rats and SPF burned rats had mild inflammatory reactions within one week after scald.The serum level of TNF-α,GM-CSF and IL-1α in three groups of rats were significantly increased after burned (P<0.05);At 24 h,the level of IL-1α in the germ-free scald rats and the scald rats infected with Pseudomonas aeruginosa were significantly higher than the SPF rats (P<0.05),while the GM-CSF content in germ-free scald rats was significantly higher than that in the scald rats infected with Pseudomonas aeruginosa and SPF rats (P<0.05).At the 3rd day,the IL-1α content in germ-free scald rats and the scald rats infected with Pseudomonas aeruginosa were significantly higher than the SPF rats (P<0.05),and the GM-CSF content in germ-free scald rats was significantly higher than that in the scald rats infected with Pseudomonas aeruginosa (P<0.05).In conclusion,germ-free scald rats reacted fiercely,and serum inflammatory factors increased rapidly,while the inflammatory response of SPF rats was slower to the deep second degree scald.Pseudomonas aeruginosa infected deep second-degree scald sterile rats had a shorter decrustation time and healing time.