Risk factors of development of gut-derived bacterial translocation in thermally injured rats

AIM: Studies have demonstrated that gut-derived bacterial translocation (BT) might play a role in the occurrence of sepsis and multiple organ dysfunction syndrome (MODS). Yet, no convincing overall analysis of risk factors for BT has been reported. The purpose of this study was to evaluate the related factors for the development of BT in burned rats. METHODS: Wistar rats were subjected to 30% third-degree burns. Then samples were taken on postburn d 1, 3, and 5. Incidence of BT and counts of mucosal bifidobacteria, fungi and E.coli mucus sIgA, degree of injury to ileal mucosa, and plasma interleukin-6 were observed. Univariate analysis and multivariate logistic regression analysis were performed. RESULTS: The overall BT rate was 53.9% (69 in 128). The result of univariate analysis showed that the levels of plasma endotoxin and interleukin-6, the counts of mucosal fungi and E. coli and the scores of ileum lesion were markedly increased in animals with BT compared with those without (P=0.000-0.005), while the levels of mucus sIgA and the counts of mucosal bifidobacteria were significantly reduced in animals with translocation compared with those without (P=0.000). There was a significant positive correlation between mucus sIgA and the counts of mucosal bifidobacteda (r=0.74, P=0.001). Moreover, there were strong negative correlations between scores of ileum-lesion and counts of bifidobacteria (r=-0.67, P=-0.001). Multivariate logistic regression revealed that ileum lesion score (odds ratio [OR] 45.52, 95% confidence interval [CI] 5.25-394.80), and counts of mucosal bifidobacteria (OR 0.039, 95% CI 0.0032-0.48) were independent predictors of BT secondary to severe burns. CONCLUSION: Ileal lesion score and counts of mucosal bifidobacteria can be chosen as independent prognosis factors of the development of BT. Specific interventions targeting these high-risk factors might be implemented to attenuate BT, including strategies for repair of damaged intestinal mucosae and restoration of the balance of gastrointestinal flora.

Relationship between lymphocyte apoptosis and endotoxin translocation after thermal injury in rats

AIM：To investigate the relationship between lymphocyte papotosis in peripheral blood,spleen and mesenteric lymph nodes(MLN)and endotoxin translocation after thermal injury in rats.METHODS:In a wistar rat model infilicted with 30% TBSA Ⅲdegree scalding,serum LPS levels in portal vein and vena cava were quantified by tachypleus amebocyte lysate(TAL) technique.The analysis of peripheral bolld lymphocyte was employed in in situ Cell Death Detection Kit and evaluated by flow cytometry.Apoptotic lymphocytes in paraffinembedded spleen and MLN sections were examined by histologic analysis,in situ deoxynucleotidyl transferase dUTP nick-end labeling (TUNEL)and peroxidase(POD) staining.The imagines were taken by Cooldccd camera system,and the count and optical density value (transmission light) of apoptotic lymphocytes were analyzed with software Spot and lmagine proplus 4.10a(IPP4.10a).RESULTS:In the Period of 3 to 48 postburn hours(PBHs) serum LPS level(×10%3EU.L^-1)in portal vein(2.11±0.02,5.66±0.20,3.70±0.22,2.56±0.28,0.90±0.11)was higher than that in vena cava(0.63±0.01,.1.53±0.18,0.83±0.32,0.52±0.12,0.23±0.02,P<0.01),but both increased sharply in postburn rats(P<0.01)and reached a peak at 6 PBH.Analysius of apoptotic lymphocytes showed that the proportion(%) of postburn apoptotic cells was much higher than that in healthy rats(8.34±1.53,8.13±1.81,20.77±3.94,23.90±3.92,11.23±1.35and 13.26±2.09at3,6,12,24,48and 72 PBH,respectively,vs 3.99±1.72,P<0.01)especially after 6 PBH.The concentrations of lymphocytic apoptosis at 12 and 24 PBH were markedly higher than that at other time points.Meantime,few apoptotic lymphocytes were found in normal MLN,but increased postburn obviously(3±1vs 546±83,285±39,149±30,58±10,36±11and 33±9in turn,P<0.01),especially at 3 PBH,whereas apoptotic lymphocytes were concentrated in splenic cortex before the burn and decreased obviously during 72PBHs(499±186vs12±8，19±15,12±7,100±15,123±25and 226±26in turn,P<0.01) though a slight rise was found in the medulla after 24 PHB Optical density of apoptotic lymplhocytes was significantly reduced in spleen in the 24 PBHs and raised in MLN during 48 PBHs than that prior to the burn,respectively.CONCLUSION:Gut-origin LPS is a major cause of endotoxemia taken place early in rate following severe thermal injury and could induce extensive lymphocyts apoptosis in blood and MLN,which suggests an immunosuppression state could follow the initial injury and favores a septic state based on apoptotic mechanism.

Dynamic changes of interleukin-1, interleukin-6 and tumor necrosis factor in intermingled skin graft in burned rats

To compare the dynamic changes of interleukin 1 (IL 1), interleukin 6 (IL 6), and tumor necrosis factor (TNF) in intermingled skin graft with those in other types of skin grafts in rats. Methods: A 10% 15% third degree burn was created in 180 Spregue Dawley (SD) rats. After removing the scar, skin grafts were performed on the open wounds immediately with autoskin (aus, n=54), alloskin (als, n=54) and intermingled skin (n=36). That is to say, in the intermingled skin graft, a big piece of alloskin (mals) was grafted first, and 3 days later, small pieces of autoskin (maus) were embedded in the alloskin. The rest 36 rats were taken as the controls. And the biological activities of IL 1, IL 6 and TNF in graft sheets in each group were detected after skin graft. Results: The levels of IL 1, IL 6 and TNF in the aus group decreased steadily after their initial elevations, whereas in the als group they increased significantly and kept on the peak level in the later phases. In the intermingled group, there appeared a lowest IL 1 level in the mals and a highest one in the maus simultaneously at 7 (4) days (The number out of parenthesis is the days after transplanting with alloskin sheets, and the number in parenthesis is the days after embedding autoskin sheets in the intermingled skin graft. Similarly hereinafter.) after skin graft (P< 0.01 ), and the high level in the maus abruptly decreased at 14 (11) days after skin graft. At exactly the same phase on day 7 (4), a prominent peaked IL 6 in the mals occurred. In the later phases, the levels of TNF remained relatively low both in the mals and in the maus. From day 7 (4) on, each cytokine fluctuation in the mals synchronized with that in the maus. The longer the post transplantation period lasted, the more the positive cytokine correlated between the mals and the maus. Conclusions: The low levels of IL 1 and TNF may be important factors to lighten the intensity of local rejection in the intermingled skin graft. The temporarily peaked IL 6 is both an inducer which induces the production of local IL 1 receptor antagonists and soluble TNF receptors and a signal which indicates a local enhancement of Th 2 cells. The mild rejection process and the synchronized cytokine level during the later phases suggest a possible chimerism between the mals and the maus.