Relationship between hepatic CTGF expression and routine blood tests at the time of liver transplantation for biliary atresia: hope or hype for a biomarker of hepatic fibrosis

Abstract

Background: Progressive hepatic fibrosis (HF) is a prominent feature of biliary atresia (BA), the most common indication for liver transplantation (LT) in children. Despite its importance in BA, HF is not evaluated in routine patient care because the invasiveness of liver biopsy makes histologic monitoring of fibrosis unfeasible. Therefore, the identification of noninvasive markers to assess HF is desirable especially in children.

Purpose: The main goal of this pilot project was to establish an investigational framework correlating hepatic expression of fibrogenic markers with routine blood tests in BA.

Methods: Using liver explants from patients with BA (n = 26), immune-expression of connective tissue growth factor (CTGF), a key fibrogenic cytokine was determined using horseradish-labeled antibodies. Expression intensities of lobular (L-CTGF) and portal (P-CTGF) CTGF were determined by using ImageJ software. These CTGF intensities were correlated with blood tests performed at the time of LT. Correlation coefficients were determined for each blood test variable versus mean L-CTGF and P-CTGF expression intensities. A P-value of less than 0.05 was considered statistically significant.

Results: All patients had end-stage liver disease and persistent cholestasis at the time of LT. Kendall tau (τ) rank correlation coefficient for L-CTGF and white blood cell (WBC) was inversed (-0.52; P ≤ 0.02). Similar but statistically nonsignificant inverse relationships were noted between L-CTGF and prothrombin time (PT) (-0.15; P ≤ 0.4), international normalized ratio (INR) (-0.14; P ≤ 0.5), and platelet count (-0.36; P ≤ 0.09). Inversed (τ) rank correlation coefficients were also evident between P-CTGF expression and gamma-glutamyl transpeptidase (GGT), PT, INR, and platelet count. Pearson correlation coefficients for combinational analysis of standardized total bilirubin (TB), alkaline phosphatase, GGT, and platelet count with L-CTGF (0.33; P = 0.3) and P-CTGF (0.06; P = 0.8), were not significant. Similar analysis for alanine aminotransferase, TB, and GGT combination (L-CTGF, 0.16; P = 0.5; P-CTGF -0.3; P = 0.2) as well as WBC, platelet count, and TB (L-CTGF: -0.36; P = 0.09; P-CTGF -0.33; P = 0.13) also revealed nonsignificant results.

Conclusion: Hepatic expression of fibrogenic markers can be correlated with routinely performed blood tests in patients with BA. We document that although a trend of inverse relationship is noted, hepatic CTGF expression does not correlate well with routinely performed blood tests in advanced BA. Further work is required to determine more reliable ways of noninvasive diagnosis of HF.

Keywords: blood tests; connective tissue growth factor; fibrogenesis; liver fibrosis.