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- Zhang, Xiangnan, et al.
(författare)
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Gut Bacterial Indole-3-acetic Acid Induced Immune Promotion Mediates Preventive Effects of Fu Brick Tea Polyphenols on Experimental Colitis
- 2023
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Ingår i: Journal of Agricultural and Food Chemistry. - : American Chemical Society (ACS). - 0021-8561 .- 1520-5118. ; 71:2, s. 1201-1213
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Tidskriftsartikel (refereegranskat)abstract
- Ulcerative colitis has been consistently associated with gut microbiota imbalance and disturbed immune system. Emerging research suggests a protective function of polyphenols on prevention and treatment of ulcerative colitis, yet underlying mechanisms remain unclear. Fu brick tea, a postfermented tea, contains abundant polyphenols with anti-inflammatory and antioxidant properties. In the present study, we found that prophylactic supplementation of polyphenols extracted from Fu brick tea (FBTP) dose-dependently alleviated colitis symptoms, immune cells infiltration, and pro-inflammatory cytokines secretion in mice suffering dextran sulfate sodium induced murine colitis. FBTP substantially reshaped gut microbiota and promoted microbial transformation of tryptophan into indole-3-acetic acid (I3A), thereafter leading to aryl hydrocarbon receptor (AHR)-mediated protection from colitis through enhanced expressions of IL-22 and tight junction proteins (i.e., ZO-1, occluding and claudin-1) in colon. Multiomics integration analyses revealed strong connections between I3A, tryptophan-metabolizing bacteria, AHR activity, and pathological phenotypes of colitis. Notably, FBTP failed to significantly alleviate colitis symptoms in the absence of gut microbiota, while intragastric administration of I3A could imitate benefits of FBTP on colitis alleviation and intestinal epithelial homeostasis through a direct enhancement in AHR activity in microbiota-depleted mice. These findings further determine the key role of gut microbiota controlled I3A-AHR signaling in mediating the FBTP on colitis alleviation. This study provides the first data proposing the FBTP as a natural prebiotic for colitis alleviation through the gut microbiota-dependent modulation of the AHR pathway. Most importantly, we also identified I3A as a key microbial metabolite targeted by FBTP for exhibiting health-promoting effects.
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- Yan, Tao, et al.
(författare)
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Diet-rich in wheat bran modulates tryptophan metabolism and AhR/IL-22 signalling mediated metabolic health and gut dysbacteriosis: A novel prebiotic-like activity of wheat bran
- 2023
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Ingår i: Food Research International. - : Elsevier BV. - 0963-9969 .- 1873-7145. ; 163
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Tidskriftsartikel (refereegranskat)abstract
- Tryptophan metabolism has shown to involve in pathogenesis of various metabolic diseases. Gut microbiota-orientated diets hold great potentials to improve metabolic health via regulating tryptophan metabolism. The present study showed that the 6-week high fat diet (HFD) disturbed tryptophan metabolism accompanied with gut dysbacteriosis, also influenced the dietary tryptophan induced changes in cecum microbiome and serum metabolome in mice. The colonic expressions of aryl hydrocarbon receptor (AhR) and interleukin-22 (IL-22) were significantly reduced in mice fed on HFD. Notably, a diet- rich in wheat bran effectively inhibited transformation of tryptophan to kynurenine-pathway metabolites, while increased melatonin and microbial catabolites, i.e. indole-3-propionic acid, indole-3-acetaldehyde and 5-hydroxy-indole-3-acetic acid. Such regulatory effects were accompanied with reduced fasting glucose and total triglycerides, and promoted AhR and IL-22 levels in HFD mice. Wheat bran increased the abundance of health promoting bacteria (e.g., Akkermansia and Lactobacillus), which were significantly correlated with tryptophan derived indolic metabolites. Additionally, beneficial modulatory effects of wheat bran on indolic metabolites in associations with gut dysbacteriosis from type 2 diabetes patients were confirmed in vitro fecal fermentation experiment. Our study proves the detrimental effects of HFD induced gut dysbacteriosis on tryptophan metabolism that may influence immune modulation, and provides novel insights in the mechanisms by which wheat bran could induce health benefits.
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