Project description:Intestinal lipid absorption, the entry point for fats into the body, requires the coordinated actions of bile acids and lipases. Here, we uncover distinct yet cooperative roles of bile acids in driving the differential uptake of dietary fatty acids. We first decreased the bile acid pool size by disrupting the rate-limiting enzyme in bile acid synthesis, Cyp7a1, using liver-directed gene editing in mice. Compared with lipase inhibition, reduced bile acids prevented diet-induced obesity, increased anorectic hormones, suppressed excessive eating, and improved systemic lipid metabolism. Remarkably, decreasing bile acids selectively reduced the absorption of saturated fatty acids but preserved polyunsaturated fatty acids. By targeting additional bile acid enzymes, we identified specific functions of individual bile acid species. Mechanistically, we show that cholic acid preferentially solubilizes polyunsaturated fatty acids into mixed micelles for intestinal uptake. Our studies demonstrate that bile acids can selectively control fatty acid uptake, revealing insights for future interventions in metabolic diseases.
Project description:Intrahepatic cholestasis of pregnancy (ICP) is estimated to impact between 0.4% and 5% of pregnancies worldwide. This disease is associated with elevated maternal bile acids and frequently untoward neonatal outcomes such as respiratory distress and asphyxia. Multiple candidate genes have been implicated, but none have provided insight into the mechanisms of neonatal respiratory distress and death. Herein our studies demonstrate that maternal cholestasis (due to Abcb11 deficiency) produces 100% neonatal death within 24h due to atelectasis producing pulmonary hypoxia, which recapitulates the respiratory distress and asphyxia of human ICP. We show that these neonates have elevated pulmonary bile acids that are associated with disrupted structure of pulmonary surfactant. Maternal absence of Nr1i2 superimposed upon Abcb11 deficiency strongly increased neonatal survival and is directly related to reduced maternal bile acid concentrations. The mechanism accounting for reduced serum bile acids in the mothers deficient in both Nr1i2 and Abcb11 appears related to disrupted reabsorption of intestinal bile acids due to changes in transporter expression. These findings provide novel insights into pulmonary failure by revealing bile acids capability to disrupt the structure of surfactant producing collapsed alveoli, pulmonary failure and ultimately death. These findings have important implications for neonatal health especially when maternal bile acids are elevated during pregnancy and highlight a potential pathway and targets amenable to therapeutic intervention to ameliorate this condition.
Project description:Intrahepatic cholestasis of pregnancy (ICP) is estimated to impact between 0.4% and 5% of pregnancies worldwide. This disease is associated with elevated maternal bile acids and frequently untoward neonatal outcomes such as respiratory distress and asphyxia. Multiple candidate genes have been implicated, but none have provided insight into the mechanisms of neonatal respiratory distress and death. Herein our studies demonstrate that maternal cholestasis (due to Abcb11 deficiency) produces 100% neonatal death within 24h due to atelectasis producing pulmonary hypoxia, which recapitulates the respiratory distress and asphyxia of human ICP. We show that these neonates have elevated pulmonary bile acids that are associated with disrupted structure of pulmonary surfactant. Maternal absence of Nr1i2 superimposed upon Abcb11 deficiency strongly increased neonatal survival and is directly related to reduced maternal bile acid concentrations. The mechanism accounting for reduced serum bile acids in the mothers deficient in both Nr1i2 and Abcb11 appears related to disrupted reabsorption of intestinal bile acids due to changes in transporter expression. These findings provide novel insights into pulmonary failure by revealing bile acids capability to disrupt the structure of surfactant producing collapsed alveoli, pulmonary failure and ultimately death. These findings have important implications for neonatal health especially when maternal bile acids are elevated during pregnancy and highlight a potential pathway and targets amenable to therapeutic intervention to ameliorate this condition. We used microarrays to measure changes in gene expression profiles in lung tissues from Abcb11+/- lungs after interbreeding C57BL/6 wild-type female or C57BL/6 Abcb11-/- female mice against either C57BL/6 wild-type male mice or C57BL/6 Abcb11-/- male mice to create only heterozygote offspring. We also measured profiles in liver tissues from age-matched C57BL/6 wild-type and C57BL/6 Abcb11-/- mice. Lung tissues were collected from day E17.5, E18.5 and neonatal (N0) mice. Liver tissues were collected from 1.5-month-old C57BL/6 wildtype and Abcb11-/- mice.
Project description:Liver sinusoidal endothelial cells (LSEC) are unique endothelial cell typelining the sinusoids of the liver and we have shown that these cells respond in a unique matter when exposed to saturated and unsaturated free fatty acids (FFA) and bile acids. We used microarray to analyze the transcriptional differences between the LSEC exposed to free fatty acids and bile acid receptor agonists to further shed light on their role in non-alcoholic fatty liver disease. The Murine Liver Sinusoidal Endothelial Cell Line (TSEC) was treated with palmitic and oleic acid or the bile acid receptor agonist INT-767 for 8 hours. Total RNA was then harvested to determine transcriptional differences.
Project description:Tumor organoids of a patient with microsatellite stable (MSS) colorectal cancer were co-incubated with primary bile acids (CA, GCA, TCA; 100 µM) to analyze the effect of bile acids on tumorigenesis of colorectal cancer.
Project description:To further investigate the potential functions of Streptomyces in the gut, the bile acid-induction experiment was conducted utilizing mass spectrometry for identification. Bile acids (BAs), crucial primary metabolites of cholesterol metabolism, play a vital role in lipid digestion and absorption, enterohepatic circulation, and metabolic regulation. Notably, elevated intestinal bile acid levels are observed during high-fat diet consumption. In the present study, Streptomyces microflavus was stimulated with four distinct bile acids: CA, DCA, CDCA, and UDCA. Subsequently, bacterial cells were harvested, proteins extracted, and data-independent acquisition (DIA)-based proteomic identification performed.
Project description:Liver sinusoidal endothelial cells (LSEC) are unique endothelial cell typelining the sinusoids of the liver and we have shown that these cells respond in a unique matter when exposed to saturated and unsaturated free fatty acids (FFA) and bile acids. We used microarray to analyze the transcriptional differences between the LSEC exposed to free fatty acids and bile acid receptor agonists to further shed light on their role in non-alcoholic fatty liver disease.
Project description:Transcriptional profiling of probiotic Lactobacillus rhamnosus strain GG mid-exponential pH-controlled bioreactor cultures before and after exposure to bovine bile (0.2% ox gall). Keywords: bile, stress response
Project description:Initial single 2fold probe was designed at the Landegren lab in Uppsala University, and the following experiments were performed at the Broad Institute at the Mikkelsen lab.