Calprotectin in bile: a disease severity marker in patients with primary sclerosing cholangitis.

GOALS: Our aim was to evaluate the diagnostic potential of calprotectin in serum and bile of patients with primary sclerosing cholangitis (PSC).
BACKGROUND: PSC is a chronic cholestatic liver disease of unknown etiology. It is characterized by progressive inflammation and fibrosis of the bile ducts leading to biliary cirrhosis and eventually liver failure. Reliable markers for disease activity and severity are still lacking. Subunits of calprotectin, a fecal marker of inflammation in inflammatory bowel disease, have been recently identified in bile. STUDY: Calprotectin was measured in patients with PSC (n=56), cholangiocarcinoma (CC) complicating PSC (CC/PSC) (n=13), CC (n=30), and bile duct stones in bile (n=38) and serum (n=73) by enzyme-linked immunosorbent assay in a cross-sectional study. PSC patients were categorized by the Mayo risk score (MRS) to characterize the disease severity.
RESULTS: Calprotectin is present in bile, and the median concentration was significantly higher in PSC patients (P<0.05). Stratification of PSC patients by MRS showed significantly elevated calprotectin levels in bile in the MRS-high group (P<0.05). Calprotectin and MRS correlated significantly (P<0.05). The presence or absence of inflammatory bowel disease in PSC patients did not alter calprotectin levels in bile. Serum AP and calprotectin in bile correlated significantly (P=0.013). No significant correlation was found for other liver-related parameters. In contrast, serum calprotectin levels were significantly higher in patients with CC, but there was no association with PSC or disease activity/severity.
CONCLUSIONS: Calprotectin in bile is a promising disease marker in patients with PSC with a potential prognostic value.