Lychee (Litchi chinensis Sonn.) Pulp Phenolics Activate the Short-Chain Fatty Acid-Free Fatty Acid Receptor Anti-inflammatory Pathway by Regulating Microbiota and Mitigate Intestinal Barrier Damage in Dextran Sulfate Sodium-Induced Colitis in Mice

Abstract

The preventive effect of lychee pulp phenolics (LPP) on dextran sulfate sodium (DSS)-induced colitis of mice and its underlying mechanisms were investigated in this research. LPP supplementation mitigated DSS-induced breakage of the gut barrier as evidenced by the increased tight junction proteins and the enhanced integrity of epithelial cells. Both LPP and 5-ASA treatments could downregulate the expressions of toll-like receptor 4 (TLR-4), NOD protein-like receptor 3 (NLRP3), and proinflammatory cytokines to normal levels. Notably, treatment with LPP at a dosage of 500 mg/kg/day effectively upregulated FFAR2 and FFAR3 expression and contents of short-chain fatty acids (SCFAs), suggesting the activation of the SCFA-FFAR (free fatty acid receptor) pathway. Consistently, the abundances of probiotic taxa and microbiota (Akkermansia, Lactobacillus, Coprococcus, and Bacteroides uniformis) associated with SCFA synthesis were elevated, whereas harmful bacteria (Enterococcus and Aggregatibacter) were suppressed. These data indicate that LPP ameliorates gut barrier damage, activates the microbiota-SCFA-FFAR signaling cascade, and suppresses the TLR4/NLRP3-NF-κB pathway, and therefore, LPP supplementation could be a promising way to protect the intestinal tract.

Green Pea (Pisum sativum L.) Hull Polyphenol Extracts Ameliorate DSS-Induced Colitis through Keap1/Nrf2 Pathway and Gut Microbiota Modulation

“…Gut microbiota plays an important role in maintaining the intestinal barrier function, and its imbalance is considered a key factor in the onset of IBD [34,37]. DSS can change the composition of the gut microbiota to aggravate colitis, which is manifested by inhibiting the abundance of probiotics and promoting the growth of harmful bacteria.…”

“…Enterotoxigenic Bacteroides fragilis, which secretes 20 KDa pro-inflammatory zinc-dependent metalloproteinase toxin, is not only related to blood infections and intra-abdominal abscesses, but also a potential instigator of colitis [18,38]. As a probiotic, Lactobacillaceae can not only secrete SCFAs, but also activate T-helper to resist foreign pathogens and regulate the secretion of cytokines [31,37]. Lachnospiraceae also belongs to SCFA-producing bacteria [21].…”

Novel Catabolic Pathway of Quercetin-3-O-Rutinose-7-O-α-L-Rhamnoside by Lactobacillus plantarum GDMCC 1.140: The Direct Fission of C-Ring

“…Therefore, it was considered that the rhamnosidase from B. thetaiotaomicron displayed high specificity. A significant increment in B. thetaiotaomicron abundance was observed in mice after the treatment with LPP ( 13 ). The difference between in-vitro and in-vivo proliferative effect of LPP on B. thetaiotaomicron suggested the symbiotic relationship among various bacterial species in the colonic environment.…”

“…Based on retention times measured for the authentic standards, the identification of peaks detected at 280 nm was confirmed. Compounds were quantified with the standard curves established by the corresponding phenolic substances, according to our previous work ( 13 ). Results were expressed as mg per gram dry weight (DW) of LPP.…”

“…It was also inferred that the microbial units that were enriched by phenolics supplementation participated in the phenolic metabolism. High-throughput sequencing data showed that the abundances of Bacteroides (especially for B. uniformis and B. thetaiotaomicron ) and Lactobacillus in mice were effectively upregulated after LPP supplementation for 2 weeks ( 13 ). Therefore, it was reasonable to infer that the metabolism of LPP might be related to some microbial species referring to Bacteroides or Lactobacillus .…”