The Diversity And Composition Of Digestive Tract Microflora In Patients With Radiation Esophagitis

Research Background:Radiation esophagitis is a common complication after the radiotherapy of thoracic tumors.The main pathology change is local congestion and edema of esophageal mucosa,and further manifestation of local stenosis and scar-like changes.The main clinical symptoms of patients are eating discomfort,burning sensation,pain.The diagnosis of radiation esophagitis according to the symptoms lack of specific diagnostic criteria.The incidence and progression of radiation esophagitis are positively related to the radiation dose.The emergence of radiation esophagitis not only directly affect the life quality of patients,and even affect the long-term treatment of patients.The research has been widely carried out study the relationship of the change of human bacterial microbiota and the occurrence of diseases using the High-throughput sequencing technology combined with metagenomics.Most of the studies pay attention to the intestinal microbial using the fecal specimens as medium,care about the relation of intestinal microbiology and metabolic diseases and digestive tract diseases.Esophageal as an important part of the digestive tract,has been shows that there are abundant bacterial colony structure of the esophagus.The transform of bacterial flora directly related to the occurring of fungal esophagitis,reflux esophagitis and other diseases.Radiation esophagitis as a common complication in the radiotherapy of thoracic tumors,the changes in the structure of the flora during radiotherapy is not clear.The study of the diversity characteristics of flora in radiation esophagitis patients through high-throughput sequencing technology hasn't see in the report.Objective:To explore the diversity of intestinal bacterial flora by using the high-throughput sequencing technique combined with metagenomics.Evaluated the effect of radiotherapy to esophagitis bacterial flora to find the specific strains related to the occurrence of radiation esophagitis.Provided theoretical guidance to explore the new way of prevention and treatment of radioactive esophagitis.Materials and Methods:In this study,using the fecal flora as the representative of the intestinal flora,Collected the samples in three time periods:one for patients without any treatment;two for patients with radiation esophagitis clinical symptoms but before corresponding treatment;three for patients had finished the radiotherapy treatment.And we collected saliva samples from healthy people as contrast.In this study,we collected samples from 32 patients and 41 healthy people.The main experimental steps are as follows:1.Gene fragment acquisition:The bacterial DNA in the sample was extracted by physical crushing combined with chemical cleavage,and the 16S rDNA fragment of the bacteria was extracted by the restriction endonuclease.2.Propagation of gene fragments:design the amplification primers,propagate the hypervariable region of 16s rDNA by using polymerase chain reaction(PCR).3.Gene sequencing:use the 454-pyrophosphate high-throughput sequencing technology sequence the Amplicons of 16S rDNA gene to obtain the original data.4.Species annotation:analysis of the original data,identification of bacterial operational taxonomic unit(OTU,equivalent to the level of species),according to the similarity of OTU classification of bacteria distribution,and identify the species of bacteria by compare the bacterial gene library.5.Statistical analysis:Intraplate complexity analysis(a diversity)was performed by dilution curve,Chaol curve and Shannon index using bioinformatics techniques.Compare the microflora structure of patients with radiation esophagitis and healthy people by main coordinate analysis(PCoA)and UPGMA cluster analysis(? diversity),to find disease-related bacteria.Results:1.After pretreatment of the data,the data of samples were satisfied with the follow-up analysis requirements.Through the analysis of a diversity,it was confirmed that the samples were sufficient to cover the bacterial species in the samples.The abundance and uniformity of the samples were good.2.Species after high-throughput sequencing showed that the diversity of the flora in patients with radiation esophagitis was significantly different from that in the healthy people.The flora had changed a lot after the radiotherapy.3.The main bacterial components of the digestive tract with radiation esophagitis patients are firmicutes,bacteroidetes,proteobacteria,fusobacteria,actinobacteria,cyanobacteria,tenericutes.The species composition is similar like that of healthy people,and the abundance of bacteria is obviously different.4.Different primary disease of radiation esophagitis patients have no significant difference in intestinal flora composition.Conclusions:1.Based on high-throughput sequencing technology combined with bioinformatics to confirm the existence of a large number of human digestive tract bacterial community,the composition of the flora has variety and characteristic.2.There were significant differences in the composition of digestive tract flora between patients with radiation esophagitis and healthy people,and the dominant species were similar,and the abundance of the bacteria was changed obviously.3.The changes of intestinal flora structure in patients with radiation esophagitis were significantly different from those before treatment,and the change process and the effect of radiation on the abundance of bacteria need to be further studied.4.Different primary disease of radiation esophagitis patients have no significant difference in intestinal flora composition.