Lactobacillus rhamnosus MN-431 metabolic tryptophan alleviates complementary food-induced diarrhea through PXR-NF-κB pathway and AHR-Th17 cell response pathways.

SCOPE: Lactobacillus rhamnosus MN-431 tryptophan broth culture (MN-431TBC) could prevent CFID. However, it was not clear whether this effect was 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) were investigated. Only MN-431 TBS could significantly prevent CFID, indicating that indole derivatives produced by MN-431 could exert antidiarrheal effects. Intestinal morphological analysis revealed that MN-431 TBS could 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 revealed the indole derivatives in MN-431 TBS were IAld and skatole. Cell experiments demonstrated that MN-431 TBS promoted the transcription of AHR and PXR, comparable to the synergistic effect of IAld and skatole. MN-431 TBS could activate AHR and reduce 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 could also activate PXR and reduce the concentrations of TNF-α and IL-6 in intestine and serum.

CONCLUSION: MN-431 TBS, containing IAld and skatole, could exert anti-CFID effects through the AHR-Th17 and PXR-NF-κB pathways. This article is protected by copyright. All rights reserved.