Gut microbiota, dietary taurine, and fiber shift taurine homeostasis in adipose tissue of calorie-restricted mice to impact fat loss

Previously, we demonstrated that caloric restriction (CR) stimulates the synthesis, conjugation, secretion, and deconjugation of taurine and bile acids in the intestine, as well as their reuptake. Given taurine's potent antiobesogenic properties, this study aimed to assess whether the CR-induced shift in taurine homeostasis contributes to adipose tissue loss. To verify that, male C57Bl/6 mice were subjected to 20% CR or ad libitum feeding, with variations in cage bedding and gut microbiota conditions. Additional groups received taurine supplementation or were fed a low-taurine diet (LTD). The results showed that in CR animals, taurine derived from the intestine was preferentially trafficked to epididymal white adipose tissue (eWAT) over other tested organs. Besides increased levels of taurine transporter TauT, gene expression of Cysteine dioxygenase (Cdo) involved in taurine synthesis was upregulated in CR eWAT. Taurine concentration in adipocytes was inversely correlated with fat pad weight of CR mice. Different types of cage bedding did not impact eWAT taurine levels; however, the lack of bedding and consumption of a diet high in soluble fiber did. Depleting gut microbiota with antibiotics or inhibiting bile salt hydrolase (BSH) activity reduced WAT taurine concentration in CR mice. Taurine supplementation increased taurine levels in WAT and brown adipose tissue (BAT), promoting fat loss in CR animals. LTD consumption blunted WAT loss in CR animals, with negligible impact on BAT. This study provides multiple insights into taurine's role in CR-triggered fat loss and describes a novel communication path between the liver, gut, microbiota, and WAT, with taurine acting as a messenger.