Farnesoid X receptor agonists attenuate colonic epithelial secretory function and prevent experimental diarrhoea in vivo
- Magdalena S Mroz1,
- Niamh Keating1,
- Joseph B Ward1,
- Rafiquel Sarker2,
- Silvie Amu3,
- Gabriella Aviello3,
- Mark Donowitz2,
- Padraic G Fallon3,
- Stephen J Keely1
- 1Department of Molecular Medicine, RCSI Education and Research Centre, Beaumont Hospital, Dublin, Ireland
- 2Division of Gastroenterology, Department of Medicine, The Johns Hopkins University School of Medicine, Baltimore, Maryland, USA
- 3School of Medicine, Trinity Biomedical Sciences Institute, Trinity College Dublin, Dublin 2, Ireland
- Correspondence to Stephen J Keely, Molecular Medicine Laboratories, RCSI Education and Research Centre, Smurfit Building, Beaumont Hospital, Dublin 9, Ireland;
- Received 12 April 2013
- Revised 3 July 2013
- Accepted 9 July 2013
- Published Online First 5 August 2013
Objective Bile acids are important regulators of intestinal physiology, and the nuclear bile acid receptor, farnesoid X receptor (FXR), is emerging as a promising therapeutic target for several intestinal disorders. Here, we investigated a role for FXR in regulating intestinal fluid and electrolyte transport and the potential for FXR agonists in treating diarrhoeal diseases.
Design Electrogenic ion transport was measured as changes in short-circuit current across voltage-clamped T84 cell monolayers or mouse tissues in Ussing chambers. NHE3 activity was measured as BCECF fluorescence in Caco-2 cells. Protein expression was measured by immunoblotting and cell surface biotinylation. Antidiarrhoeal efficacy of GW4064 was assessed using two in vivo mouse models: the ovalbumin-induced diarrhoea model and cholera toxin (CTX)-induced intestinal fluid accumulation.
Results GW4064 (5 μmol/L; 24 h), a specific FXR agonist, induced nuclear translocation of the receptor in T84 cells and attenuated Cl− secretory responses to both Ca2+ and cAMP-dependent agonists. GW4064 also prevented agonist-induced inhibition of NHE3 in Caco-2 cells. In mice, intraperitoneal administration of GW4064 (50 mg/mL) also inhibited Ca2+ and cAMP-dependent secretory responses across ex vivo colonic tissues and prevented ovalbumin-induced diarrhoea and CTX-induced intestinal fluid accumulation in vivo. At the molecular level, FXR activation attenuated apical Cl− currents by inhibiting expression of cystic fibrosis transmembrane conductance regulator channels and inhibited basolateral Na+/K+-ATPase activity without altering expression of the protein.
Conclusions These data reveal a novel antisecretory role for the FXR in colonic epithelial cells and suggest that FXR agonists have excellent potential for development as a new class of antidiarrheal drugs.