Effects Of Gut Flora Dysfunction Induced By Polymyxin E On Gut Barrier Function And Bacterial Trans Location

In normal condition, the microorganism of intestinal tract maintains the state of equilibrium, and each kind of bacterium forms the commensal microflora according to certain quantity and proportion, building biology barrier to prevent intestinal bacteria trans location. Gut flora dysfunction refers to a state that the sensitive intestinal bacteria is suppressed, while the opportunistic pathogen increased, thus causing the quantity and the proportion of intestinal bacteria changed exceptionally. The damage of intestinal barrier usually occurs as one of the severe complications after serious wound, major surgery of abdomen, radiotherapy chemotherapy and so on, provoking gut flora disturbance, bacteriemia and the malnutrition. The intestinal mucous membrane barrier inflammation and perish weakly will cause the intestinal mucous membrane barrier break, triggering the intestinal bacteria trans location, bacteria and toxins in the intestinal tract enter blood circulation through the permeable intestinal mucosa, and trigger SIRS and MODS. Thus bacterial translocation will be the result of the damage of mechanical and biological barrier.Polymyxin E (colistin) is a group of positive ion multi-peptide antibiotics isolated from colistin from Bacillus colistinus, Colistin binds to the gram-negative bacterial cell membrane phospholipids, producing a disruptive physiochemical effect, which leads to cell membrane permeability changes and ultimately cell death. Most gram-negative microorganisms are susceptible to colistin, including multidrug-resistant Acinetobacter baumannii, Pseudomonas aeruginosa strains and Proteus species. Therefore, we proposed to induce mouse model of gut flora dysfunction by reducing the amount of Enterobacteria via intragastric administration of polymyxin E, and study the effects of gut flora dysfunction on gut barrier function and bacterial trans location.Part1Effect of gut flora dysfunction induced by polymyxin E on gut barrier function and bacterial translocation in normal miceObjective:to explore the effect of gut flora dysfunction induced by ploymyxin E on gut barrier function and bacterial translocation in mice.Methods:Twenty adult male BALB/c mice were randomly assigned to two groups, each group has10mice. Experimental mice received intragastric ploymyxin E (0.2g/kg in0.2ml Normal Saline, q.d) for seven days. Control mice were administered the same amount of saline. Pathomorphological change of intestinal mucosa, gut flora, protein expression of tight junction, the rate of bacterial translocation were observed. Results:Administration of ploymyxin E (experimental group) was associated with a significant decrease (vs Control) of cecum luminal and mucosal surface enterobacteria. Experimental mice showed an obvious injury (vs Control) under an optical microscope, such as prominent hyperemia of intestinal mucosa, sparse intestinal villi, and a small amount of necrosis and shedding in villus tip. Under an electron microscope, decrease of electron dense material in the tight junction of intestinal epithelium was also found in the experimental mice. Protein expression of Claudin-1, Occludin and ZO-1of intestinal mucosa was also decreased, and significant increase (vs Control) of bacterial translocation could be found in the experimental group.Conclusions:intragastric administration of Polymyxin E can induce gut flora dysfunction, destory gut barrier function and lead to bacterial translocation. Part2The influence of Polymyxin E on the gut barrier and bacterial translocation of mice with gut flora disorders induced by intragastric administration of non-pathogenic E.coliObjective:In order to study the short-term and long-term effect of polymyxin E on the intestinal barrier and bacterial translocation, we use polymyxin E to gavage the mice with gut flora disorder induced by intragastric administration of non-pathogenic E.coli.Method:thirty two male BAL B/C mice were randomly divided in to four groups, each group contained8mice, sham group (group A) mice received intragastric normal saline; Control group (group B) mice received intragastric normal saline after drinking bacteria-containing water (non-pathogenic E.coli108/ml) freely for8weeks; experimental group intragastric administration control group of polymyxin E (0.2g/kg in0.2ml normal saline) for4days (group C) and10days (group D). Intestinal bacteria colony, mucosal histopathology, ultrastructure of tight junction (TJ), the expression and immunofluorescence of TJ proteins, and distant organs (liver, spleen, kidney and lymph node) bacterial translocation were determined and observed.Results:Administration of polymyxin E for4days (group C) improved gut flora, reduced histopathological and TJ injury, increased the expression of TJ proteins and reduced bacterial translocation to distant organs. Using polymyxin E for10days (group D) aggravated gut dysbiosis, histopathological injury and TJ, reduced the expression of TJ proteins and increased bacterial translocation to remote organs.Conclusion:Properly use of antibiotics can ameliorate intestinal dysbiosis, protect intestinal barrier function, and reduce the bacterial translocation. Antibiotics abuse not only disturb intestinal flora, but also aggravate intestinal mucosa damage and increase the rate of bacterial translocation.