Vascular adhesion protein-1 is elevated in primary sclerosing cholangitis, is predictive of clinical outcome and facilitates recruitment of gut-tropic lymphocytes to liver in a substrate-dependent manner.

OBJECTIVE: Primary sclerosing cholangitis (PSC) is the classical hepatobiliary manifestation of IBD. This clinical association is linked pathologically to the recruitment of mucosal T cells to the liver, via vascular adhesion protein (VAP)-1-dependent enzyme activity. Our aim was to examine the expression, function and enzymatic activation of the ectoenzyme VAP-1 in patients with PSC. DESIGN: We examined VAP-1 expression in patients with PSC, correlated levels with clinical characteristics and determined the functional consequences of enzyme activation by specific enzyme substrates on hepatic endothelium. RESULTS: The intrahepatic enzyme activity of VAP-1 was elevated in PSC versus immune-mediated disease controls and non-diseased liver (p<0.001). The adhesion of gut-tropic α4ß7+lymphocytes to hepatic endothelial cells in vitro under flow was attenuated by 50% following administration of the VAP-1 inhibitor semicarbazide (p<0.01). Of a number of natural VAP-1 substrates tested, cysteamine-which can be secreted by inflamed colonic epithelium and gut bacteria-was the most efficient (yielded the highest enzymatic rate) and efficacious in its ability to induce expression of functional mucosal addressin cell adhesion molecule-1 on hepatic endothelium. In a prospectively evaluated patient cohort with PSC, elevated serum soluble (s)VAP-1 levels predicted poorer transplant-free survival for patients, independently (HR: 3.85, p=0.003) and additively (HR: 2.02, p=0.012) of the presence of liver cirrhosis. CONCLUSIONS: VAP-1 expression is increased in PSC, facilitates adhesion of gut-tropic lymphocytes to liver endothelium in a substrate-dependent manner, and elevated levels of its circulating form predict clinical outcome in patients.

Serum vascular adhesion protein-1 is higher in subjects with early stages of chronic kidney disease.

OBJECTIVES: An increased level of serum vascular adhesion protein-1 (VAP-1) has been found in patients with diabetes mellitus and vascular disorders. This study examined whether serum VAP-1 levels are associated with chronic kidney disease (CKD). DESIGN AND METHODS: We included 262 subjects aged 30 and above with fasting plasma glucose level <7 mmol/L checked within 1 year. First morning urine specimens were collected. Microalbuminuria was defined if urinary albumin-to-creatinine ratio > or =30 microg/mg creatinine. The glomerular filtration rate (GFR) was estimated. CKD stages were defined according to the suggestions of the National Kidney Foundation. Serum VAP-1 levels were analyzed by immunofluorometric assay. RESULTS: Serum VAP-1 levels were positively associated with the urinary albumin-to-creatinine ratio (r=0.29, p<0.0001) and negatively associated with estimated GFR (r=-0.24, p=0.0001). Subjects with CKD stage 2 (N=51) and stage 3 (N=91) had significantly higher levels of serum VAP-1 than those without CKD (p=0.0003 and p=0.035, adjusted for age and gender, respectively). A high serum VAP-1 level was associated with the presence of CKD (OR 1.63 for 1 SD increase of VAP-1, p=0.018), adjusting for age, sex, and smoking. Ordered logit models revealed that high serum VAP-1 levels correlated with advanced stages of CKD. CONCLUSIONS: Serum levels of VAP-1 are associated with the severity of kidney damage or stages of kidney disease. The true mechanism which links the serum VAP-1 and CKD remains to be elucidated in further studies.