Abstract:

[Objective] This study was conducted to characterize the changes in intestinal microbiota composition and serum inflammatory factors as well as their correlation in rats with diarrhea-predominant irritable bowel syndrome （IBS-D）. [Method] A total of 12 male SD rats were divided into a normal group and a model group according to the random number table, with 6 rats in each group. The IBS-D rat models were established using acetic acid colon perfusion combined with restraint stimulation method. Normal and model rats were given 10 mL/（kg·BW） of distilled water by gavage once per day. Samples were collected after 8 consecutive days of intervention. ELISA assay was used to measure the serum levels of IL-10, IL-6 and TNF-α. The species composition of intestinal microbiota, single factor network, and correlation of intestinal microbiota with serum inflammatory factors in the two groups of rats were examined using the 16S rDNA sequencing data. [Result] In comparison with the normal group, the serum level of IL-10 in the model group decreased （P<0.01）, while the serum levels of IL-6 and TNF-α increased （P<0.01）. The comparison of species composition showed that there were differences in intestinal microbiota at the phylum and genus levels between the two groups. Compared with the normal group, at the phylum level, the relative abundance of Bacteroidota in the model group increased, while that of Firmicutes and other bacteria decreased （P<0.05 or P<0.01）; at the genus level, the relative abundance of Alloprevotella in the model group elevated, while that of Lachnospiraceae_NK4A136_group and other bacteria reduced （P<0.05）. Analysis of indicator species of intestinal microbiota showed that Candidatus_Stoquefichus, Candidatus_Arthromitus and other bacteria in the model group had significant （P<0.05） affects. The results of single factor network analysis showed that in the model group, the differential microbiota Alloprevotella was negatively correlated with Roseburia, Romboutsia and Lachnospiraceae_NK4A136_group, while Lachnospiraceae_NK4A136_group was positively correlated with Romboutsia, UCG-003, Oscillibacter and Roseburia. The results of correlation analysis showed that at the phylum level, Fusobacteriota, Myxococcota, Proteobacteria and Halanaerobiaeota were positively correlated with serum level of IL-10; Bacteroidota was negatively correlated with serum level of IL-10, and positively correlated with serum level of IL-6; Campilobacterota and Halanaerobiaeota were negatively correlated with serum level of IL-6; Desulfobacterota, Campilobacterota and Halanaerobiaeota were negatively correlated with serum level of TNF-α. At the genus level, Alloprevotella, Prevotellaceae_UCG-001 and Prevotella were positively correlated with serum level of IL-10, while Alloprevotella and Prevotellaceae_UCG-001 were negatively correlated with serum levels of IL-6 and TNF-α; Lachnospiraceae_NK4A136_group, UCG-003 and Oscillibacter were negatively correlated with serum level of IL-10, and positively correlated with serum levels of IL-6 and TNF-α. The differences in the above results were statistically significant （P<0.05 or P<0.01 or P<0.001）. [Conclusion] Compared with healthy rats, IBS-D rats have different intestinal microbiota composition and serum levels of inflammatory factors, and there is correlation between intestinal microbiota and serum inflammatory factors. The results obtained in this study provide a useful reference for clinical detection of inflammatory factors to guide the selection of probiotics or antibiotics.

Key words: diarrhea-predominant irritable bowel syndrome, intestinal microbiota, serum inflammatory factor, correlation