Analysis Of Intestinal Microbiota And Function In Ulcerative Colitis Based On Species Co-occurrence Network

Objective:To reveal the formation mechanism of intestinal microbiota in Ulcerative Colitis(UC),clarify the changes in ecological functions,and excavate the core microbiota related to the incidence of UC,so as to provide scientific basis for the targeted diagnosis and treatment of UC based on intestinal microbiota.Methods:The intestinal mucosa of UC and its healthy spouse was collected and the V3-V4 hypervariable region of 16S rRNA was sequenced.The differences of a and β diversity between the UC group and the UC healthy partner group were analyzed at the three levels of the whole community,the phylum and the core/peripheral network,respectively.The Species co-occurrence network(SCN)of intestinal microbiota was established to compare the differences in the topology of the co-occurrence network.The positive and negative ratios of the bacterial community network were calculated by functional gene annotation and biological information labeling algorithm.To elucidate the interaction mode among its microbiota and find the key microbiota related to the incidence of UC.Results:1.At the whole community level,there was no difference in the Hill number of mucosal microbiota between the healthy spouse group and the UC group(P<0.05).At the main phylum level,the Hill number of Firmicutes and Bacteroidetes in UC group decreased compared with those in healthy mate group(P<0.05).At the core/peripheral species level,the Hill number of core species in UC group was significantly higher than that in healthy people(P<0.05),and the difference was more obvious with the increase of q.2.The level of the entire mucosal community and the Operational taxunits(OTUs)of Firmicutes are not less than the number of the total OTUs expected at random.The actual total OTUs number of Bacteroidetes and Proteobacteria was significantly lower than the expected total OTUs number(P<0.05).At the core/peripheral species level,the actual common OTUs numbers of both core and peripheral species were lower than the random expected common OTUs numbers(P<0.05).3.At the overall community level,the positive and negative connection ratio(P/N)of nodes in UC-SCN was 4 times higher than that in healthy SCN.At UC-SCN level,the number of negative connections in Firmicutes and between Firmicutes and Proteobacteria was mainly reduced to less than half of that in healthy SCNs.The number of negative connections decreased in both core species and peripheral species,and the decline was obvious in the core species.4.Clostridium tertium,Odoribacter splanchnicus,Ruminococcus gnavus,Flavonifractor plautii showed a significant difference in abundance between the UC group and the healthy group,with P/N ratio<0.5 in SCN of the healthy group,while P/N ratio increased significantly in UC-SCN.Conclusions:1,The results of changes in intestinal microbiota diversity of UC were related to the scale selected in the study.At the whole community level,the diversity of UC mucosa microbiome changed.At the philum level,the mucosal microbiota of UC group changed significantly.In addition,the changes in the diversity of the core/periphery network can be used as a new scale to reveal the changing pattern of UC microbiota diversity.2.The increase of P/N at UC-SCN indicates that UC is less able to inhibit potential opportunistic "pathogenic bacteria" than healthy people.3.Found 4 opportunistic "pathogenic bacteria" that have potential significance for the diagnosis and treatment of UC:Clostridium tertium,Odoribacter splanchnicus,Ruminococcus gnavus,Flavonifractor plautii.They were suppressed in healthy individuals,but were significantly enriched in UC.