Biliary phosphatidylcholine and lysophosphatidylcholine profiles in sclerosing cholangitis

Abstract

Aim: To analyze phospholipid profiles in intrahepatic bile from patients with primary sclerosing cholangitis (PSC) and secondary sclerosing cholangitis (SSC).

Methods: Intrahepatic bile specimens collected via endoscopic retrograde cholangiography from 41 patients were analyzed. Fourteen of these patients were diagnosed with PSC, 10 with SSC, 11 with choledocholithiasis or no identifiable biliary disease, and 6 with cholangiocellular carcinoma (CCC). Bile acid, cholesterol, protein, and bilirubin contents as well as pancreas lipase activity in bile were determined by biochemical methods. Phosphatidylcholine (PC) and lysophosphatidylcholine (LPC) species were quantified using nano-electrospray ionization tandem mass spectrometry.

Results: Bile from all the examined patient groups showed a remarkably similar PC and LPC species composition, with only minor statistical differences. Total biliary PC concentrations were highest in controls (8030 ± 1843 μmol/L) and lowest in patients with CCC (1969 ± 981 μmol/L) (P = 0.005, controls vs SSC and CCC, respectively, P < 0.05). LPC contents in bile were overall low (4.2% ± 1.8%). Biliary LPC/PC ratios and ratios of biliary PC to bilirubin, PC to cholesterol, PC to protein, and PC to bile acids showed no intergroup differences.

Conclusion: PC and LPC profiles being similar in patients with or without sclerosing cholangitis, these phospholipids are likely not of major pathogenetic importance in this disease group.

Keywords: Bile; Cholangiocellular carcinoma; Lysophosphatidylcholine; Mass spectrometry; Phosphatidylcholine; Primary sclerosing cholangitis; Secondary sclerosing cholangitis.

Figure 1

Electrospray mass spectrum of the total lipid extract from human bile of a patient with primary sclerosing cholangitis. For explanation of standards view Table 2.