OR22-01 Sex Differences In Enterohepatic Circulation Mediated By Hepatic FXR And SHP Depletions In Mice

Abstract

Abstract Disclosure: F. Reichardt: None. C. Galuke: None. S. Anakk: None. Bile acids are transported via the portal vein to the liver after their absorption through the distal intestine mucosa. In hepatocytes, they activate the nuclear receptors, Farnesoid-X-receptor (FXR) and Small Heterodimer Partner (SHP), which exert negative feedback on bile acids synthesis. The aim of this project is to decipher how hepatic FXR/SHP deletion impact BA composition, enterohepatic circulation, and its cross talk with the gut microbiota. Enterohepatic circulation was investigated by measuring total bile acids in intestinal, hepatic tissues and fecal tissues and in portal and systemic blood, using 3-5 months-old fed female and male wildtype (WT) and LDKO (liver specific FXR/SHP depletions) mice. We also examined if intestinal dysmotility mediated the alteration in bile acids absorption by following methylene blue dye progression in overnight fasted WT and LDKO mice. Portal and systemic total bile acids concentrations were higher in LDKO mice compared to WT, despite of no significant change in hepatic and intestinal levels. Sex differences were seen only in LDKO mice with higher systemic and portal concentrations in females compared to males. Intestinal transit time and fecal total bile acids were equivalent between all mice. Intriguingly, we observed that portal bile acids levels correlated to the liver weight to body weight ratio and to cecum weight to body weight ratio, suggesting that bile acids alterations within the enterohepatic loop could be associated to cecal dysbiosis. These preliminary findings highlight altered BA recirculation in LDKO mice compared to WT, but also between females and males LDKO. We hypothesize that these sex-specific modifications are associated with intestinal dysbiosis impacting bile acid compositions, and to test this we will be analyzing the influence of sex, and BA composition on the microbiome. Further investigations using fasted or HFD-fed LDKO and WT mice will help us to better understand the role of hepatic FXR and SHP in bile acids circulation between intestine and liver. Acknowledgement: University of Illinois Urbana-Champaign, American Cancer Society and Cancer Center at Illinois Seed grant Presentation: Saturday, June 17, 2023