The Role Of Intestinal Microecology In Severe Acute Pancreatitis Complicated With Intestinal Dysfunction

The incidence of AP is increasing with the improvement of people’s living standard and changes for living habits.Although people have made significant progress in the diagnosis and treatment for AP in the last few decades,the mortality of patients with SAP is abOTU 20-30% [46].Besides,SAP is characterised by complicated pathogenesis and multiple organs involved which makes it more difficult to treat and research.According to a large number of studies,SAP often hanppens with acute gastrointestinal injury,resulting in intestinal barrier dysfunction.The intestinal barrier is mainly composed of mechanical barrier,chemical barrier,microbiological barrier and immune barrier.Under normal circumstances,it can play an important role in preventing gut microbiota and its harmful products from entering the blood stream and abdominal organs.The gut microbiota will pass through the intestinal barrier into the circulatory system and abdominal organs due to the impaired intestinal barrier and increased intestinal permeability,resulting in intestinal infection,which is the main cause of death for patients with SAP.There are many explanations ab OTU the mechanism of acute gastrointestinal injury in AP,but it is not clear yet.Animal experiments such as Van et al.[47] also found that in the presence of SAP,the gram positive cocci,gram negative bacilli and anaerobic bacteria in the intestine were overgrowth.These results suggest that SAP may cause gut microbiota disorder,destroy the original structure of microbial barrier,and affect the intestinal barrier function.If the bacteria products such as endotoxin translocates to the blood,which will stimulate inflammatory cytokines,aggravate the systemic inflammatory response,and cause a second attack to the pancreas,even cause or aggravate multiple organ failure syndrome,leading to increased risk of death in patients with SAP [48].In summary,we hypothesize that changes in gut microbiota may be involved in acute gastrointestinal injury and inflammatory response in acute pancreatitis,and may have an impact on the secondary infection in patients with AP.In order to verify the above hypothesis,we carried OTU the following experiments.1.ObjectiveTo investigate the changes of gut microbiota in patients with AP,the effect of gut microbiota on acute gastrointestinal injury and inflammatory response in acutepancreatitis,and the effect of gut microbiota on the prognosis of AP.2.MethodPatients with AP were divided into severe acute pancreatitis group(SAP group,n=25)and mild acute pancreatitis group(MAP group,n=37).The severe acute pancreatitis group was subdivided into severe acute pancreatitis group(TSAP group,n=6)and moderate severe acute pancreatitis group(MSAP group,n=19).Stool and serum specimens were collected in above patients and healthy people(the H group,n=31).The bacterial 16 S rDNA V3-V4 region of fecal specimens was detected by high throughput sequencing technique to detect the diversity and abundance of gut microbiota.The serum levels of CRP,PCT and IL-6 were detected by ELISA.In addition,we also collected the clinical data of patients with acute pancreatitis and to evaluate the conditions,including APACHE II scores and AGI grades,and follow-up of patients with or withOTU secondary infection.Compared the detection results of different groups and studyed the influence of gut microbiota on inflammatory indexes and AGI grades,and its effect on the prognosis of gut microbiota.Using the SPSS 18.0 version software system to analyse the datas.Specifically speaking,measurement datas were described with mean and standard deviation(?x ± SD),and the difference between groups was compared by t test,one-way ANOVA or nonparametric test,and the correlation was analysed by simple linear correlation analysis.Categorical datas were described with number and percentage,and the difference between groups was compared by Fishier exact test or chi square test.As for the multivariate analysis,logistic regression analysis was used.3.Result(1)Comparion of CRP,PCT,IL-6 level and AGI grades between different groups(a)Comparion of CRP,PCT,IL-6 level between different groups:The mean CRP level was 203.77 ± 112.71 mg/L,the median and quartile of PCT were 1.23(0.63,3.29)pm/mL,the mean level of IL-6 was 74.25 ± 78.04 pg/ml in SAP group.While the mean CRP level was 103.50 ± 62.14 mg/L,the PCT level was 0.62(0.45,1.10)pm/mL,the mean level of IL-6 was 32.15 ± 27.88 pg/ml in MAPgroup,and the mean level of CRP was 5.88 ± 3.86 mg/L,the PCT level was 0.16(0.08,0.32)pm/m L,the mean level of IL-6 was 4.89 ± 3.52 pg/ml in H group.According to the results of single factor analysis and t test,compared with H group,the levels of CRP,PCT and IL-6 in SAP group and MAP group were significantly higher,and the levels of CRP,PCT and IL-6 in SAP group were significantly higher than those in group MAP(P < 0.05).The mean CRP was 217.67 ± 67.37 mg/L,the mean PCT level was 8.05 ± 9.87pm/mL,the mean level of IL-6 was 63.90 ± 23.88 pg/ml in TSAP group.The mean CRP was 199.38 ± 124.87 mg/L,the mean PCT level was 1.31 ± 1.25 pm/m L,the mean level of IL-6 was 77.52 ± 88.96 pg/ml in MSAP group.According to the t test results,the CRP and IL-6 were close between TSAP and MSAP group,the difference was not statistically significant(P=0.737 and P=0.718).But the PCT increased significantly in TSAP group,the difference was statistically significant(P < 0.001).(b)Comparion of AGI grades between different groups: All patients in the SAP group and MAP group happened with AGI,and the AGI grades were decided according to the highest grades during the first week of hospitalization.The highest AGI grade was grade IV while the lowest AGI grade was grade II in the SAP group,and there were4%(n=1)patients with grade IV,20%(n=5)with grade III and 76%(n=19)with grade II in the SAP group.The highest AGI grade was grade II while the lowest AGI grade was grade I in the MAP group,and there were 10.8%(n=4)patients with grade II and89.2%(n=33)with grade I in the MAP group.Because there were no acute grastrointestinal injury in the healthy people,so all people from the H group with grade0(n=31).According to the Fisher exact test,the difference between the three groups was statistically significant,and the AGI grade of the SAP group was significantly higher than that of the MAP group(P < 0.001).There were 16.7%(n=1)patients with grade IV of AGI and 16.7%(n=1)patients with grade III in the group TSAP,while all patients in the MSAP group were with grade III(n=19).According to the Fisher exact test,the TSAP group and MSAP group had statistically significant differences in AGI grade,and the AGI grade of TSAP group was higher than that of MSAP group(P < 0.001).(2)The changes of gut microbiota in patients with AP: According to the single factor analysis and t test results,the difference of intestinal bacterial content was not statistically significant(P > 0.05)between SAP group,MAP group and H group.When compared with gut microbiota in H group,the gut microbiota abundance changed significantly in SAP group and MAP group.Compared with gut microbiota in MSAP group,the abundance of some flora had change in TSAP group.(a)Comparion of the diversity of bacterial flora: According to the analysis of the Alpha diversity,there were significant difference(P > 0.05)between the diversity index in SAP group,MAP group and H group,including observed speciesindex,chao1 index,Shannon index,Simpson index and PD_whole_tree index.(b)Comparison of the bacterial abundance: According to the results of nonparametric test,the abundance of gut microbiota in patients with AP was significantly changed at different taxon.For the taxon of phylum,the abundance of Bacteroidetes decreased while the eveness of Proteobacteria increased;for the taxon of class,the abundance of Bacteroides decreased while the eveness of Gammaproteobacteria increased;for the taxon of order,the abundance of Bacteroidales decreased while the eveness of Enterobacteriales increased;for the taxon of falimy,the abundance of Bacteroidaceae and Lachnospiraceae decreased while the eveness of Enterobacteriaceae and Enterococcaceae increased;for the taxon of genus,the abundance of Bacteroides,Roseburia,Sutterella and Phascolarctobacterium decreased while the eveness of Escherichia/Shigella,Enterococcus and Lactobacillus increased.Compared with MSAP group,the abundance of Escherichia/Shigella and Sutterella decreased significantly in TSAP group.(3)The role of gut microbiota in the inflammatory response and intestinal dysfunction in AP:Simple linear correlation analysis was used to study the relationship between the abundance of dominant bacteria and the level of CRP,PCT and IL-6.The results showed that there was a significant correlation between the abundance of intestinal flora and the level of CRP,PCT and IL-6.Under the condition of AP,the increase and difference between groups of the level of CRP,PCT and IL-6 was related to the chages of gut microbiota,including the decreased abundance of Bacteroidetes,Lachnospiraceae,Roseburia,Sutterella and Phascolarctobacterium,and the increased eveness of Proteobacteria,Enterobacteriales and enterococcus,etc.Based on the above results,it is suggested that a variety of gut microbita may be involved in the inflammatory response in AP,and they may play an important role in inhibiting or promoting inflammation.According to the results of the simple linear correlation analysis,there was a correlation between the abundance of gut microbiota at different taxonomic levels and AGI grading.The Bacteroidetes,Lachnospiraceae,Roseburia,分类位置未定的毛螺菌属,Prevotella and Fusobacterium may have a protective effect on the gastrointestinal mucosa,while Proteobacteria,Enterobacteriales,Escherichia/Shigella and Pseudomonas may damage the gastrointestinal mucosa.These intestinal bacteria may play an important role in the begining and development of acute gastrointestinal injury in AP.(4)Related factors for secondary infection in patients with SAP: In SAP group,there were 6 cases of infective pancreatic necrosis,5 happened in the TSAP group while1 in the MSAP group.Do logistic regression analysis for those factors that were significantly different in above analysis,including CRP,PCT,IL-6,AGI grade and predominant gut microbiota.The results showed that only PCT and AGI grade has significant effects on the secondary infection in patients with SAP.And patients with SAP is inclined to be complicated by infection which with a higher level of PCT and AGI grade.However,CRP,PCT,IL-6 and gut microbiota has no significant effect on the secondary infection in patients with SAP.4.ConclusionThe changes of gut microbiota may be involved in the intestinal mucosal injury and inflammation during the course of AP and relative to the severity of the disease,but the abundance of dominant bacteria may have no significant relationship with the risk of secondary infection in patients with SAP.