Regulation of serotonin production by specific microbes from piglet gut

Tryptophan metabolism and piglet diarrhea: Where we stand and the challenges ahead

The intestinal architecture of piglets is vulnerable to disruption during weaning transition and leads to diarrhea, frequently accompanied by inflammation and metabolic disturbances (including amino acid metabolism). Tryptophan (Trp) plays an essential role in orchestrating intestinal immune tolerance through its metabolism via the kynurenine, 5-hydroxytryptamine, or indole pathways, which could be dictated by the gut microbiota either directly or indirectly. Emerging evidence suggests a strong association between piglet diarrhea and Trp metabolism. Here we aim to summarize the intricate balance of microbiota-host crosstalk by analyzing alterations in both the host and microbial pathways of Trp and discuss how Trp metabolism may affect piglet diarrhea. Overall, this review could provide valuable insights to explore effective strategies for managing piglet diarrhea and the related challenges.

Free fatty acid 3 receptor agonist AR420626 reduces allergic responses in asthma and eczema in mice

Free fatty acid 3 receptor (FFA3; previously GPR41) is a G protein-coupled receptor that senses short-chain fatty acids and dietary metabolites produced by the gut microbiota. FFA3 deficiency reportedly exacerbates inflammatory events in asthma. Herein, we aimed to determine the therapeutic potential of FFA3 agonists in treating inflammatory diseases. We investigated the effects of N-(2,5-dichlorophenyl)-4-(furan-2-yl)-2-methyl-5-oxo-1,4,5,6,7,8-hexahydroquinoline-3-carboxamide (AR420626), an FFA3 agonist, in in vivo models of chemically induced allergic asthma and eczema in BALB/c mice. Administration of AR420626 decreased the number of immune cells in the bronchoalveolar lavage fluid and skin. AR420626 suppressed inflammatory cytokine expression in the lung and skin tissues. Histological examination revealed that AR420626 suppressed inflammation in the lungs and skin. Treatment with AR420626 significantly suppressed the enhanced lymph node size and inflammatory cytokine levels. Overall, FFA3 agonist AR420626 could suppress allergic asthma and eczema, implying that activation of FFA3 might be a therapeutic target for allergic diseases.