Abstract
The gut microflora dysbiosis has been closely related with the inflammatory bowel disease (IBD). In this study, the effect of polysaccharides from Chrysanthemum morifolium Ramat on the gut microbiota was evaluated by ulcerative colitis (UC) rat model. Physiological and pathological analyses suggested that Chrysanthemum polysaccharides possessed notably protective effects on UC in vivo. Based on the Illumina MiSeq platform, 16S rRNA sequencing of the rat colonic contents indicated that the intestinal flora structure remarkably changed in the model rats and the tendency was alleviated to a certain degree by treatment with different dosages of Chrysanthemum polysaccharides. In normal groups, there were more Firmicutes than Bacteroidetes, but this change lost at the pathological state. Following Chrysanthemum polysaccharides, rising Firmicutes/Bacteroidetes ratio was validated. Besides the microbial diversity and the community richness of the UC rats were improved by Chrysanthemum polysaccharides, the composition of intestinal microflora in the model group were also restored after oral administration of Chrysanthemum polysaccharides. The abundance of opportunistic pathogens was decreased (Escherichia, Enterococcus and Prevotella), while the levels of protective bacteria such as Butyricicoccus and Clostridium (butyrate-producing bacteria), Lactobacillus and Bifidobacterium (probiotics), Lachnospiraceae and Rikenellaceae elevated in various degrees. Correlation analysis between intestinal flora and biochemical factors suggested that the relative abundance of protective bacteria was positively correlated with the levels of anti-inflammatory cytokines such as IL-4, IL-10 and IL-11, while aggressive bacteria were positively correlated with proinflammatory cytokine such as IL-23、IL-6、 IF-17、TNF-α、IL-1β and IFN-γ. The above results showed that the intestinal flora were closely related to the secretion and expression of cytokines in the body, and they interacted with each other to regulate immune function. Thus, Chrysanthemum polysaccharides could ameliorate ulcerative colitis by fostering beneficial intestinal flora growth, modulating the balance of intestinal microecology and restoring the immune system.
Highlights
Inflammatory bowel disease (IBD) encompasses two clinical forms such as ulcerative colitis (UC) and Crohn’s disease (CD), which possesses some symptoms such as weight loss, severe diarrhea and abdominal pain, seriously impairing the quality of life [1, 2]
Compared to the normal group (Figure 1A), trinitrobenzene sulfonic acid (TNBS)-induced colitis rats (M) remarkably lost weight throughout the trial period (p < 0.01), which was rescued by the Chrysanthemum polysaccharides treatment (HP 200 mg/kg, TNBS/ethanol + middle dose treatment group (MP) 100 mg/kg, TNBS/ethanol + low dose treatment group (LP) 50 mg/kg)
The results indicated that severe pathological changes such as mucosal lesion, necrosis and infiltration of inflammatory cells including monocytes and neutrophils occurred in the colonic tissues of model rats, which were alleviated by Chrysanthemum polysaccharides treatment, especially the MP (100 mg/kg) and LP (50 mg/kg) (p < 0.01) (Figure 1D)
Summary
Inflammatory bowel disease (IBD) encompasses two clinical forms such as ulcerative colitis (UC) and Crohn’s disease (CD), which possesses some symptoms such as weight loss, severe diarrhea and abdominal pain, seriously impairing the quality of life [1, 2]. The pathogenesis of IBD remains unclear, though several factors have been associated with disease development including immune dysregulation, genetics, risk alleles, barrier dysfunction, environmental exposures and, more recently, compositional changes in the communities of bacteria that inhabit the gut [3,4,5]. The intestinal microflora dysbiosis is closely related to the gastrointestinal disease IBD [6]. The intestinal microflora, approximately 100 trillion microorganisms, is a large bacterial community that colonizes in the intestine, with powerfully metabolic activities for various enzymes and other functions such as intestinal epithelial cell proliferation/differentiation, intestinal development and barrier function that affect the physiology and pathology of the host’s mucosal immune system [7,8,9]. Many researches have overwhelmingly verified the roles of bacteria in IBD. Chronic intestinal inflammation in transgenic and gene knock-out rats occurs under standard laboratory conditions, but not in a germ-free environment [10, 11]
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