Altered bile acid and coproporphyrin-I disposition in patients with autosomal dominant polycystic kidney disease

Aims: Serum, liver and urinary bile acids are increased, and hepatic transport protein levels are decreased in a non-clinical model of polycystic kidney disease. Similar changes in patients with autosomal dominant polycystic kidney disease (ADPKD) may predispose them to drug-induced liver injury (DILI) and hepatic drug-drug interactions (DDIs). Systemic coproporphyrin-I (CP-I), an endogenous biomarker for hepatic OATP1B function and MRP2 substrate, is used to evaluate OATP1B-mediated DDI risk in humans. In this clinical observational cohort-comparison study, bile acid profiles and CP-I concentrations in healthy volunteers and patients with ADPKD were compared.

Methods: Serum and urine samples from healthy volunteers (n = 16) and patients with ADPKD (n = 8) were collected. Serum bile acids, and serum and urine CP-I concentrations, were quantified by ultra-performance liquid chromatography tandem mass spectrometry (UPLC-MS/MS).

Results: Patients with ADPKD exhibited increased serum concentrations of total (1.3-fold) and taurine-conjugated (2.8-fold) bile acids compared to healthy volunteers. Specifically, serum concentrations of six bile acids known to be more hydrophobic/hepatotoxic (glycochenodeoxycholate, taurochenodeoxycholate, taurodeoxycholate, lithocholate, glycolithocholate and taurolithocholate) were increased (1.5-, 2.9-, 2.8-, 1.6-, 1.7- and 2.7-fold, respectively) in patients with ADPKD. Furthermore, serum CP-I concentrations were elevated and the renal clearance of CP-I was reduced in patients with ADPKD compared to healthy volunteers.

Conclusions: Increased exposure to bile acids may increase susceptibility to DILI in some patients with ADPKD. Furthermore, the observed increase in serum CP-I concentrations could be attributed, in part, to impaired OATP1B function in patients with ADPKD, which could increase the risk of DDIs involving OATP1B substrates compared to healthy volunteers.