Circulating Fibroblast Growth Factor 21 Is A Sensitive Biomarker for Severe Ischemia/reperfusion Injury in Patients with Liver Transplantation

Abstract

Hepatic ischemia/reperfusion (I/R) injury is a major cause of morbidity and mortality after liver surgery. Therefore, it is important to identity reliable biomarkers to assist early diagnosis of hepatic I/R injury. This study aimed to investigate the potential of serum levels of fibroblast growth factor 21 (FGF21) as a biomarker for hepatic I/R injury in patients with liver transplantation. Two independent cohorts of liver transplantation patients were recruited for determination of serum levels of FGF21, ALT, and AST. The results demonstrated that serum FGF21 at 2 hours post-reperfusion in cohort-1 exhibited an approximately 20-fold elevation relative to those in healthy subjects. In blood samples dynamically collected in cohort-2, a dramatic increase in serum FGF21 levels (~25-fold) was observed at two hours after surgery, whereas the peak levels of serum ALT and AST were detected only after 24 hours. Temporal correlation analysis demonstrated a significant association of peak serum levels of FGF21 at 2 hours with the magnitude of the increase in both serum ALT and AST levels at 24 hours post transplantation. In conclusion, serum FGF21 may represent a sensitive and specific prognostic biomarker for early detection of I/R injury in patients with liver transplantation.

Figure 1. Circulating levels and hepatic expression of FGF21 were markedly increased in patients with liver transplantation.

(A) Serum FGF21 levels in 38 patients receiving liver transplantation (LTx) and age-and sex-matched healthy subjects. Blood samples from LTx patients were collected at 2 hours after hepatic artery declamping. (B) Representative receiver operator characteristic (ROC) curve for serum FGF21 determined at 2 hours post reperfusion for the prediction of severe hepatic I/R injury (defined by serum levels of AST at day 1 post liver transplantation >240 U/L). (C) Representative micrographs of hamotoxylin & Eosin-stained liver sections from the same donor liver before and after LTx (Original magnification: 100x upper; 400x, lower). (D) Hepatic FGF21 levels determined by immunohistochemistry in the same liver sections as stated in panel B (Original magnification: 100x upper; 400x, lower). (E) Semi-quantification of FGF21-positive area in micrographs shown in panel C. (F) Co-immunofluorescence staining of FGF21 with Kupffer cell marker CD68 (upper), hepatic stellate cell marker α-smooth muscle action (α-SMA, middle), and cholangiocyte marker cytokeratin 19 (lower) in liver sections collected at 2 hours post-liver transplantation (Original magnification: 1000x). Quantitative data are expressed as mean ± S.D. ^**P < 0.01.

Figure 2. Temporal changes in serum levels of ALT, AST, and FGF21 during the first 72 hours after liver transplantation (LTx).

Serum levels of ALT (A), AST (B), and FGF21 (C) were determined in blood samples collected at seven different time points (10 min, 30 min, 1 hr, 2 hr, 24 hr, 48 hr and 72 hr) after reperfusion in 13 patients with LTx. (D) Fold changes in serum ALT, AST, and FGF21 levels relative to their respective concentrations at 10 min n = 13. Data are expressed as mean ± S.D. ^**P < 0.01 vs. 10 min.

Figure 3. Association between changes in serum FGF21 levels and serum ALT and AST Levels in patients receiving liver transplantation.

Serum levels of FGF21, ALT and AST were measured at different time points in 13 patients who received liver transplants as in Fig. 2. (A,B) Correlation between the peak serum FGF21 levels at 2 hours and the peak values in serum ALT (ΔALT) and logarithmically transformed data of AST (ΔAST) expressed as net increases from 10 min to 24 hours after liver transplantation (C,D) Correlation between the increase in serum FGF21 (ΔFGF21) from 10 min to 2 hours and the increase in serum ALT (ΔALT) and logarithmically transformed data of the increase in AST (ΔAST) from 10 min to 24 hours after LTx. n = 13.