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Enhanced microbial bile acid deconjugation and impaired ileal uptake in pregnancy repress intestinal regulation of bile acid synthesis

Authors
  • Ovadia, C
  • Perdones-Montero, A
  • Spagou, K
  • Smith, A
  • Sarafian, MH
  • Gomez Romero, M
  • Bellafante, E
  • Clarke, LC
  • Sadiq, F
  • Nikolova, V
  • Mitchell, A
  • Dixon, PH
  • Santa-Pinter, N
  • Wahlström, A
  • Abu-Hayyeh, S
  • Walters, J
  • Marschall, H-U
  • Holmes, E
  • Marchesi, JR
  • Williamson, C
Publication Date
Feb 28, 2019
Source
Spiral - Imperial College Digital Repository
Keywords
Language
English
License
Unknown

Abstract

Pregnancy is associated with progressive hypercholanemia, hypercholesterolemia and hypertriglyceridemia, which can result in metabolic disease in susceptible women. Gut signals modify hepatic homeostatic pathways, linking intestinal content to metabolic activity. We sought to identify whether enteric endocrine signals contribute to raised serum bile acids observed in human and murine pregnancies, by measuring fibroblast growth factor (FGF)19/15 protein and mRNA levels, and 7α-hydroxy-4-cholesten-3-one. Terminal ileal farnesoid X receptor(FXR)-mediated gene expression and apical sodium bile acid transporter (ASBT) protein concentration were measured by qPCR and western blotting. Shotgun whole genome sequencing and UPLC-MS were used to determine the cecal microbiome and metabonome. Targeted and untargeted pathway analyses were performed to predict the systemic effects of the altered metagenome and metabolite profiles. Dietary cholic acid supplementation was used to determine whether the observed alterations could be overcome by intestinal bile acids functioning as FXR agonists. Human and murine pregnancy were associated with reduced intestinal FXR signaling, with lower FGF19/15 and resultant increased hepatic bile acid synthesis. Terminal ileal ASBT protein was reduced in murine pregnancy. Cecal bile acid conjugation was reduced in pregnancy due to elevated bile salt hydrolase-producing Bacteroidetes. Cholic acid supplementation induced intestinal FXR signaling, which was not abrogated by pregnancy, with strikingly similar changes to the microbiota and metabonome as identified in pregnancy. CONCLUSION: the altered intestinal microbiota of pregnancy enhance bile acid deconjugation, reducing ileal bile acid uptake and lowering FXR induction in enterocytes. This exacerbates the effects mediated by reduced bile acid uptake transporters in pregnancy. Thus, in pregnant women and mice, there is reduced FGF19/15-mediated hepatic repression of hepatic bile acid synthesis, resulting in hypercholanemia.

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