Haiyue Niu

Scope: Lactobacillus rhamnosus MN‐431 tryptophan broth culture (MN‐431 TBC) can prevent complementary food‐induced diarrhea (CFID). However, it is not clear whether this effect is related to indole derivatives.Methods and results: In this study, the anti‐CFID effects of different components in MN‐431 TBC including MN‐431 cells, unfermented tryptophan broth, and supernatant of MN‐431 TBC (MN‐431 TBS) are investigated. Only MN‐431 TBS can significantly prevent CFID, indicating that indole derivatives produced by MN‐431 can exert antidiarrheal effects. Intestinal morphological analysis reveals that MN‐431 TBS can increase the number of goblet cells, height of ileal villi, and length of rectal glands while also increasing the expression of ZO‐1 in colon. Furthermore, HPLC analysis reveals the indole derivatives in MN‐431 TBS are IAld and skatole. Cell experiments demonstrate that MN‐431 TBS promotes the transcription of aryl hydrocarbon receptor (AHR) and pregnane X receptor (PXR), comparable to the synergistic effect of IAld and skatole. MN‐431 TBS can activate AHR and reduces the concentrations of Th17 cell‐inflammatory factors IL‐17A and IL‐21 in intestine and IL‐17F, IL‐21, and IL‐22 in serum. MN‐431 TBS can also activate PXR and reduces the concentrations of TNF‐α and IL‐6 in intestine and serum.Conclusion: MN‐431 TBS, containing IAld and skatole, can exert anti‐CFID effects through the AHR–Th17 and PXR–NF‐κB pathways.

Aim: The intestinal microbiota contributes to infant's intestine homeostasis. This study aimed to analyse how probiotics derived from breast milk promote infant intestinal development in rat pups. Methods and results: The effect of potential probiotics derived from breast milk on development of intrauterine growth retardation (IUGR) newborn rats' intestine was investigated. Limosilactobacillus oris ML-329 and Lacticaseibacillus paracasei ML-446 exhibited good hydrophobicity percentages (p < 0.05). ML-446 showed a significant effect on intestinal length and weight (p < 0.05). Meanwhile, the villus height of the IUGR newborn rats fed with ML-329 was significantly higher compared with those fed with Lacticaseibacillus rhamnosus GG (p < 0.05). Moreover, ML-329 and ML-446 both significantly stimulated the proliferation and differentiation of intestinal epithelial cells by increasing the number of ki67-positive cells, goblet cells, and lysozyme-positive Paneth cells (p < 0.05) through Wnt and Notch pathway. Conclusions: The proliferation and differentiation stimulating effects of ML-329 and ML-446 on IECs in the jejunum, ileum, and colon were mediated by activating the Wnt pathway with increased expression of wnt, lrp5, and β-catenin genes and accumulation of β-catenin, and by downregulating the Notch signalling pathway with decreased expression of the activated notch protein. Significance and Impact of the Study: Lactobacillus could facilitate IUGR rat pups' intestinal development and enhance the proliferation of Paneth cells and goblet cells. These findings provide further insights into promotion of the intestinal development by breast milk-derived beneficial microbes in early life of the IUGR newborn rats.

Scope: Many infants suffer from complementary feeding‐induced diarrhea (CFID). Studies have shown that intestinal microbes can enhance the intestinal barrier and prevent diarrhea by producing indole derivatives that promote pregnane X receptor (PXR) expression.Methods and Results: In this study, the indole test and determination of the PXR concentration are performed on tryptophan broth cultures of 320‐suspected Lactobacillus and Enterococcus strains. Four strains that produce indole derivatives that promote the expression of PXR are screened as potential functional probiotics. Both Lactobacillus rhamnosus MN‐431 (L. rhamnosus MN‐431) and Lactobacillus oris FN‐448 (L. oris FN‐448) can colonize the intestine of rat pups, and L. rhamnosus MN‐431 can significantly decrease the incidence of diarrhea and intestinal permeability in rat pups. Using real‐time qPCR and the analysis of the intestinal morphology using immunohistochemistry, it is observed that the metabolized tryptophan from L. rhamnosus MN‐431 can reduce small intestinal mucosal damage by stimulating PXR/NF‐κB signaling and activating PXR and aryl hydrocarbon receptor. The intestinal barrier is also enhanced by promoting the expression of tight junction proteins such as Occludin and zonula occludens‐1 in baby rats.Conclusion: The results demonstrate that L. rhamnosus MN‐431 can metabolize tryptophan to prevent infantile CFID by promoting the expression of PXR.

Summary: Infants often experience complementary food‐induced diarrhoea (CFID), which occurs when infants switch from breast milk to solid foods. The relative abundances of Prevotella and Rothia were higher in stools of infants with CFID, while the relative abundances of Enterococcus and Escherichia were higher in healthy infants. The abundance of Lactobacillus spp . normally found in breast milk fed to infants with CFID was significantly reduced, and Enterococcus spp. were less abundant when diarrhoea occurred. Furthermore, Lactobacillus and Enterococcus were present as shared bacteria in both mother and infant, and they were considered potential anti‐CFID probiotics as their relative abundances in breast milk were negatively correlated to infant CFID. Kyoto encyclopedia of genes and genomes (KEGG) functional analysis showed that the function of amino acid metabolism differed between infants with CFID and healthy infants. Therefore, CFID might be related to the decomposition of proteins in food supplements. The screening revealed seven hydrolytic casein and five hydrolytic casein and rice protein isolates from 320 suspected Lactobacillus and Enterococcus isolates. The animal experiments demonstrated that a mixture of five isolates effectively hydrolysed the casein and rice protein and prevented diarrhoea in young rats. Thus, the occurrence of CFID was found to be closely related to the intestinal and breast milk microbiota, and bacteria that could assist in the digestion of cereal proteins were involved in CFID.