The pregnane X receptor and its microbiota-derived ligand indole 3-propionic acid regulate endothelium-dependent vasodilation

Vivek Krishna Pulakazhi Venu, Mahmoud Saifeddine, Koichiro Mihara, Yi Cheng Tsai, Kristoff Nieves, Laurie Alston, Sridhar Mani, Kathy D. McCoy, Morley D. Hollenberg, Simon A. Hirota

Research output: Contribution to journalArticlepeer-review

35 Scopus citations


We proposed that circulating metabolites generated by the intestinal microbiota can affect vascular function. One such metabolite, indole 3-propionic acid (IPA), can activate the pregnane X receptor(PXR), a xenobiotic-activated nuclear receptor present in many tissues, including the vascular endothelium. We hypothesized that IPA could regulate vascular function by modulating PXR activity. To test this, Pxr+/+ mice were administered broad-spectrum antibiotics for 2 wk with IPA supple-mentation. Vascular function was evaluated by bioassay using aorta and pulmonary artery ring tissue from antibiotic-treated Pxr+/+ and Pxr-/-mice, supplemented with IPA, and using aorta tissue maintained in organ culture for 24 h in the presence of IPA. Endothelium-dependent, nitric oxide(NO)-mediated muscarinic and proteinase-activated receptor 2(PAR2)-stimulated vasodilation was assessed. Endothelial nitric oxide synthase (eNOS) abundance was evaluated in intact tissue or in aorta-derived endothelial cell cultures from Pxr+/+ and Pxr-/- mice, and vascular Pxr levels were assessed in tissues obtained from Pxr+/+ mice treated with antibiotics and supplemented with IPA. Antibiotic-treated Pxr+/+ mice exhibited enhanced agonist-induced endothelium-dependent vasodilation, which was phenocopied by tissues from either Pxr-/- or germ-free mice. IPA exposure reduced the vasodilatory responses in isolated and cultured vessels. No effects of IPA were observed for tissues obtained from Pxr-/- mice. Serum nitrate levels were increased in antibiotic-treated Pxr+/+and Pxr-/- mice. eNOS abundance was increased in aorta tissues and cultured endothelium from Pxr-/- mice. PXR stimulation reduced eNOS expression in cultured endothelial cells from Pxr+/+ but not Pxr-/- mice. The microbial metabolite IPA, via the PXR, plays a key role in regulating endothelial function. Furthermore, antibiotic treatment changes PXR-mediated vascular endothelial responsiveness by upregulating eNOS.

Original languageEnglish (US)
Pages (from-to)E350-E361
JournalAmerican Journal of Physiology - Endocrinology and Metabolism
Issue number2
StatePublished - Aug 2019


  • Endothelium
  • Metabolites
  • Microbiota
  • Pregnane X receptor
  • Vasore-laxation

ASJC Scopus subject areas

  • Endocrinology, Diabetes and Metabolism
  • Physiology
  • Physiology (medical)


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