Dietary tryptophan alleviates intestinal inflammation caused by long photoperiod via gut microbiota derived tryptophan metabolites-NLRP3 pathway in broiler chickens

Light pollution is a potential risk factor for intestinal health. Tryptophan plays an important role in the inhibition of intestinal inflammation. However, the mechanism of tryptophan in alleviating intestinal inflammation caused by long photoperiod is still unclear. This study investigated the anti-inflammatory effect of dietary trypto-phan on intestinal inflammatory damage induced by long photoperiod and its potential mechanism in broiler chickens. We found that dietary tryptophan mitigated long photoperiod-induced intestinal tissue inflammatory damage and inhibited the activation of Nucleotide-Binding Oligomerization Domain, Leucine-Rich Repeat and Pyrin Domain-Containing 3 inflammasome. Moreover, dietary tryptophan significantly increased the relative abundance ofFaecalibac-terium,Enterococcus,andLachnospira-ceae_NC2004_groupwere significantly decreased the relative abundance ofRuminococcus_torques_groupandnorank_f_UCG-010under the condition of long photo period (P<0.05). The results of tryptophan targeted metabolomics show that tryptophan significantly increased indole-3-acetic acid (IAA) and indole-3 lac-tic acid (ILA), and significantly decreased xanthurenic acid (XA) under long photoperiod (P<0.05). Inconclusion, the results indicated that dietary trypto-phan alleviates intestinal inflammatory damage caused by long photoperiod via the inhibition of Nucleotide-Binding Oligomerization Domain, Leucine-Rich Repeat and Pyrin Domain-Containing 3 inflammasome activation, which was mediated by trypto-phanmetabolites. Therefore, tryptophan supplementation could be a promising way to protect the intestine health under the condition of long photoperiod.