Novel serum and bile protein markers predict primary sclerosing cholangitis disease severity and prognosis.

BACKGROUND & AIMS: Prognostic biomarkers are lacking in primary sclerosing cholangitis, hampering patient care and the development of therapy. We aimed to identify novel protein biomarkers of disease severity and prognosis in primary sclerosing cholangitis (PSC). METHODS: Using a bead-based array targeting 63 proteins, we profiled a derivation panel of Norwegian endoscopic retrograde cholangiography bile samples (55 PSC, 20 disease controls) and a Finnish validation panel (34 PSC, 10 disease controls). Selected identified proteins were measured in serum from two Norwegian PSC cohorts (n=167 [1992-2006] and n=138 [2008-2012]), inflammatory bowel disease (n=96) and healthy controls (n=100). RESULTS: In the bile derivation panel, the levels of 14 proteins were different between PSC patients and controls (p<0.05); all were confirmed in the validation panel. Twenty-four proteins in the bile derivation panel were significantly (p<0.05) different between PSC patients with mild compared to severe cholangiographic changes (modified Amsterdam criteria); this was replicated for 18 proteins in the validation panel. Interleukin (IL)-8, matrix metallopeptidase (MMP)9/lipocalin (LCN)2-complex, S100A8/9, S100A12 and tryptophan hydroxylase (TPH)2 in the bile were associated with both a PSC diagnosis and grade of cholangiographic changes. Stratifying PSC patients according to tertiles of serum IL-8, but not MMP9/LCN2 and S100A12, provided excellent discrimination for transplant-free survival both in the serum derivation and validation cohort. Furthermore, IL-8 was associated with transplant-free survival in multivariable analyses in both serum panels independently of age and disease duration, indicating an independent influence on PSC progression. However, the Enhanced Liver Fibrosis (ELF®) test and Mayo risk score proved to be stronger predictors of transplant-free survival. CONCLUSIONS: Based on assaying of biliary proteins, we have identified novel biliary and serum biomarkers as indicators of severity and prognosis in PSC. LAY SUMMARY: Prognostic biomarkers are lacking in primary sclerosing cholangitis, hampering patient care and the development of therapy. We have identified inflammatory proteins including calprotectin and IL-8 as important indicators of disease severity and prognosis in bile and serum from patients with primary sclerosing cholangitis.

The human gallbladder secretes fibroblast growth factor 19 into bile: towards defining the role of fibroblast growth factor 19 in the enterobiliary tract.

UNLABELLED: Fibroblast growth factor 19 (FGF19) plays a crucial role in the negative feedback regulation of bile salt synthesis. In the postprandial state, activation of ileal farnesoid X receptor (FXR) by bile salts results in transcriptional induction of FGF19 and elevation of circulating FGF19 levels. An intestinal-liver axis of FGF19 signaling results in down-regulation of bile salt synthesis. The aim of this study was to explore a broader signaling activity of FGF19 in organs engaged in the enterohepatic circulation of bile salts. For this aim, FGF19 expression and aspects of FGF19 signaling were studied in surgical specimens and in cell lines of hepatobiliary and intestinal origin. FGF19 messenger RNA was found to be abundantly expressed in the human gallbladder and in the common bile duct, with only minor expression observed in the ileum. Interestingly, human gallbladder bile contains high levels of FGF19 (21.9 ± 13.3 versus 0.22 ± 0.14 ng/mL in the systemic circulation). Gallbladder explants secrete 500 times more FGF19 than FXR agonist-stimulated ileal explants. Factors required for FGF19 signaling (i.e., FGFR4 and ßKlotho) are expressed in mucosal epithelial cells of the gallbladder and small intestine. FGF19 was found to activate signaling pathways in cell lines of cholangiocytic, enteroendocrine, and enterocytic origin. CONCLUSION: The combined findings raise the intriguing possibility that biliary FGF19 has a signaling function in the biliary tract that differs from its established signaling function in the portal circulation. Delineation of the target cells in bile-exposed tissues and the affected cellular pathways, as well as a possible involvement in biliary tract disorders, require further studies.