The Mechanism And Treatment Of Intestinal Mucosa Barrier Damage Post Severe Burn

Background:Intestinal mucosa barrier consists of machinery, immune and biological barriers, Mechanical barrier is formed by intestinal mucosa epithelial cells which are closely connected, it can prevent the invasion of the bacteria and endotoxin;Immune barrier is formed by intestinal mucosal lymphoid tissues, by the cellular immunity and humoral immunity function to prevent the pathogenic antigen damage;Biological barriers is formed by intestinal flora and intestinal mucosa which is closely combine, it can prevent the intestinal pathogens engraftment and intrusion. Under normal circumstances, gastrointestinal mucous barriers can protect the body from bacteria and endotoxin attacking. However, under the condition of acute stress reaction after severe burns, caused the redistribution of blood, intestinal mucosa ischemia hypoxia extremely easily. And the acute gastrointestinal mucosa ischemia hypoxia leads to intestinal mucosal barrier is damaged, causing bacteria and endotoxin translocation, which can lead to intestinal bacterial translocation to the blood circulation, where the enterogenic infection is occurred.This is the important factor cause of SIRS and MODS occurred after burns. Therefore, the prevention and treatment of intestinal mucosa barrier damage after severe burns has been extensively investigated, but the composition of biological barriers of intestinal mucosa barrier is still not clear. Thus, this study explores what changes have taken place in the intestinal flora after burns, to understand the damage of the intestinal mucosa biological barrier, and can put forward corresponding prevention and treatment strategy; According to the mechanisms of intestinal mucosal three barriers dysfunction, we taken the mixed early enteral feeding as a prevention strategy, early feeding mixed enteral feeding on severe burn patients were confirmed that nutrients can help to protect the integrity of the intestinal mucosa barrier.Objective1. By sequencing testing the feces 16 S rRNA macros genome of rat after severe burns, to explore the intestinal biological barrier variation after severe burns.2. To explore early feeding mixed enteral nutrition agent for severe burned patients protection and restoration of intestinal mucosal barrier functions.Methods10 SD rats weight(200 ~ 220) g were obtained from the third military medical university animal center, Before burns, 10 rats were given normal feeding(water and food), Without any processing. Respectively in the first three days before burns and after burns, sterile forceps were collected in fresh with a sterile container and marked as before burns and scalds, respectively. then extraction of the fecal DNA, PCR amplification of 16 S rRNA(V3, V4) area, using high-throughput of Miseq sequencing platform for gene sequencing. The detailed content of sequencing is as follows : ①The rat intestinal flora quantity OTU(Operational Taxonomic Unit) clustering : According to 97% of the similarity between sequences as a threshold divided into OTU to analyze the diversity of microorganisms. ②species taxonomy: Use RDP classifier for each sequence on the phylum, class, order, family and genus level are Species classified, coverage( The higher its value, the sample of the lower the probability of the sequence was not detected)80percent as a threshold for each sample and each species classification unit sequence abundance calculation sequence to build samples and species taxa abundance matrix. ③ The analysis of Alpha diversity :To calculate the species diversity of each sample Within the group(Richness index、Shannon index、ACE index、Chao1 index), to measure sample diversity of species. ④The analysis of Beta diversity: Used to compare the differences between two groups of samples,The representative sequence comparison reference core 16 S r RNA sequence, According to the multiple queues build representative sequences for the evolution of the node tree, Using Unifrac metric weighted weight(Calculation not only assess the species differences between samples, and joined the species abundance as weights) Algorithm to calculate sample distance, sample clustering, sample PCA. Statistics using SPSS16.0 to rows of data Paired t test.2. 24 cases of burn patients were selected from the southwest hospital, third military medical university institute of burn from August 2013 to September 2014.Which were analyzed and included in the standard. Patients were randomly divided into conventional treatment group and early enteral feeding group, 12 cases in each group. Conventional treatment group patients within 24 h after injury were treated with conventional treatment; early enteral feeding group in phase points on the basis of conventional were treated with oral glutamine, probiotics and prebiotics enteral nutrition agent 100 m L, feeding 7 days. Respectively on admission and feed after 1 day, 3 days, 7 days, 14 days, 21 days testing the the level of serum diamine oxidase(DAO),serum calcitonin(PCT),plasma endotoxin(LPS) and wound secretion and blood microbiological cultivation, observe injury within 21 days with MODS. Statistics using SPSS16.0 to data line Fisher’s exact probability method, LSD-t test, repeated measurement and analysis of variance and rank test.Results1. The Change of intestinal biological barrier in rats after severe burns experiment.① The analysis of OTU(Operational Taxonomic Unit) clustering:The rat intestinal bacteria before and after burn OTU results is close(p>0.05). Indicating that the rat bacterial flora species composition before and after burn no change. ②species taxonomy: The rat bacterial flora species composition before and after burn no change, but the number of each component have obvious difference.Which the number of beneficial bacterium Firmicutes compare to before burn obviously decreased, pathogenic bacterium Proteobacteria number compare to before burn evident increase(P<0.05).③The analysis of the Alpha diversity : Before burns and after burns compared two groups of samples within the group had no difference(p>0.05);Indicating that the two group samples has good diversity, also proved the reliability of the experimental data. ④The analysis of the Beta diversity: between two groups before and after burns, the sample group respective form a cluster, have their own characteristics;Indicating that the intestinal flora diversity had changed on species abundance.2. Evaluation of the effect of early enteral nutrition on protecting intestinal mucosa barrier of patients with severe burn① Early enteral feeding group within 7, 14 and 21 days after the injury,the serum DAO levels were significantly lower than the conventional treatment group(P<0.05); There has no significant differences between the rest time phase point(P>0.05). ② Early enteral feeding group within 7 and 14 days after injury serum PCT levels were significantly lower than the conventional treatment group(P<0.05, or P< 0.01); There has no significant differences between the rest time phase point(P>0.05).③ Early enteral feeding group patients plasma LPS level within 7 days after the injury significantly lower th an the conventional treatment group(P<0.05); There has no significant differences between the rest time phase point(P>0.05). ④The bacteria culture of blood has 2 cases positive in conventional treatment group, significantly more than that in early enteral feeding group 0 cases(P<0.05). The two groups bacteria culture of wound results is close(P>0.05). ⑤ In the conventional treatment group has observated 1 cases MODS, and no MODS occurs in early enteral feeding group(P>0.05).Conclusions1. After severe burns the composition of the rat intestinal flora had no change, But, the abundance of beneficial bacterium Firmicutes compare to before burn obviously decreased, pathogenic bacterium Proteobacteria number compare to before burn evidently increase. Indicating that the rat intestinal flora has disturbance after severe burn, the intestinal mucosa biological barrier had damaged. 2. Mixed early enteral feeding agent in severe burn patients can promoting the protection and restoration of intestinal mucous membrane barrier function, reduce inflammation, reducing the occurrence of enterogenic infection and improve the prognosis of patients.