Apelin Association with Hepatic Fibrosis and Esophageal Varices in Patients with Chronic Hepatitis C Virus

Abstract

Portal hypertension and esophageal varices complicating hepatitis C virus (HCV)-related chronic liver diseases are some of the most devastating sequelae. Angiogenesis is the hallmark of their pathogenesis. Apelin is one of the recently identified angiogenic and fibrogenic peptides. We studied apelin gene expression, apelin (rs3761581) single-nucleotide polymorphism (SNP), and serum apelin level in patients with chronic HCV, and their association with liver fibrosis and esophageal varices in 112 patients with HCV-related chronic liver disease (40 with liver cirrhosis [LC]/low-grade varices, 33 with LC/high-grade varices, and 39 with fibrotic non-cirrhotic liver/no varices) and 80 healthy control subjects. Real-time polymerase chain reaction was used for apelin gene expression assay and apelin rs3761581 SNP analysis in peripheral blood samples. The serum apelin level was measured by ELISA. Apelin gene expression was undetectable in the studied samples. The SNP analysis revealed a greater frequency of the C (mutant) allele among patients compared with control subjects (P = 0.012; odds ratio, 3.67). The serum apelin level was significantly greater in patients with LC/varices (median, 31.6 ng/L) compared with patients without LC/varices (median, 2.9 ng/L; P < 0.001). A serum apelin level cutoff value of 16.55 ng/L predicted the presence of varices, with an area under the receiver operating characteristic curve value of 0.786. A positive correlation was found between serum apelin level and grade of liver fibrosis (r = 0.346, P < 0.001) and portal hypertension (r = 0.438, P < 0.001). In conclusion, the apelin rs3761581-C allele may be associated with the progression of HCV-related chronic liver disease and varices formation, and can be considered a potential therapeutic target to control fibrosis progression. The serum apelin level provided an accurate prediction of the presence of esophageal varices.

Figure 1.

Receiver operating characteristic (ROC) curve using the serum apelin level cutoff to predict the presence of esophageal varices. A serum apelin level at cutoff value of 16.55 ng/L predicts the presence of esophageal varices (area under the ROC curve, 0.786; sensitivity, 61.6%; specificity, 97.4%; P < 0.001; 95% CI, 0.702–0.870). Diagonal segments are produced by ties.