Comparison of serological assessments in the diagnosis of liver fibrosis in bile duct ligation mice

Abstract

Liver fibrosis assessment is essential to make a prognosis and to determine the appropriate anti-fibrosis treatment. Non-invasive serum markers are widely studied in patients to assess liver fibrosis due to the limitations of liver biopsy. When using animal models to study the mechanism and intervention of hepatic fibrosis, serum markers might be useful for the continuous assessment of liver fibrosis in individual animals, which could avoid the influence of biological differences between individuals. However, it is unclear whether serum markers can assess hepatic fibrosis in the animal model. In the present study, we evaluated and compared the ability of four serum markers to assess liver fibrosis in bile duct ligation mice. According to the stages of liver fibrosis assessed by pathological changes, mice in this study were divided into five groups (F0, F1, F2, F3, and F4). Subsequently, four serum markers, aspartate aminotransferase-to-alanine aminotransferase ratio (AAR), aspartate aminotransferase-to-platelet ratio index (APRI), fibrosis index based on the 4 factors (FIB-4), and Forns Index, were calculated for each group. Furthermore, the correlations between serum markers and pathological stages and the ability of serological markers to evaluate liver fibrosis were analyzed. AAR, APRI, FIB-4, and Forns Index could significantly distinguish F0-2 from F3-4 mice. APRI, FIB-4, and Forns Index could detect F0-3 from F4 mice. Among these four markers, FIB-4 was the best able to distinguish ≥F2 and ≥F3, with area under the curve values of 0.882 and 0.92, respectively. Forns Index was best for diagnosing F4 with area under the curve value of 0.879. These results demonstrated that serum markers could be used for assessing liver fibrosis in bile duct ligation mice, and therefore, these markers might lead to more accurate diagnostic and therapeutic studies through continuous monitoring in individual animals. Impact statement The assessment of liver fibrosis is essential for making a prognosis and determining the appropriate anti-fibrosis treatment. In studies focusing on the mechanism and treatment of liver fibrosis using animal models, it would be more accurate to continuously evaluate liver fibrosis in a single animal to avoid individual biological differences. Unfortunately, it is difficult to perform continuous assessment through liver biopsy in the most commonly used rodent models. It is unclear whether serum markers, which have been used in hepatic fibrosis patients, could be used in animal models. Our results demonstrate that serum markers could be used for assessing liver fibrosis in bile duct ligation mice. This study might contribute to more accurate diagnostic and therapeutic studies through continuous monitoring in individual animals.

Keywords: Liver fibrosis; bile duct ligation; mice; serum markers.

Figure 1

The representative graphs of liver fibrosis in different stages. Histological staining of a mouse, according to the Metavir system (a) Hematoxylin-eosin (HE) and Sirius red staining, section slides obtained from each mouse and the images of three to five randomized and non-overlapping areas at 100×. (b) The mean liver collagen volume fraction calculated according to Sirius red staining. (c) Liver hydroxyproline content were detected in the left lobe of each mouse. (d) Body weight determined at the day when mice were sacrificed. *p < 0.05, **p < 0.01, ***p < 0.001 vs. F0 group; ^#p < 0.05, ^##p < 0.01, ^###p < 0.001 vs. F1 group; ^Δp < 0.05, ^ΔΔp < 0.01, ^ΔΔΔp < 0.001 vs. F2 group; ^⋆p < 0.05 vs. F3 group. (A color version of this figure is available in the online journal)

Figure 2

Boxplots of (a) AAR, (b) APRI, (c) FIB-4, and (d) Forns Index performed in controls and fibrotic mice by Metavir stages. *p < 0.05, **p < 0.01, ***p < 0.001 vs. F0 group; ^#p < 0.05, ^##p < 0.01, ^###p < 0.001 vs. F1 group; ^Δp < 0.05, ^ΔΔΔp < 0.001 vs. F2 group

Figure 3

Receiver operator characteristic (ROC) curves from four non-invasive markers with (a) threshold F0-1 vs. F2-4, (b) F0-2 vs. F3-4, and (c) F0-3 vs. F4. Diagonal segments are produced by ties. AAR: aspartate aminotransferase-to-alanine aminotransferase ratio; APRI: aspartate aminotransferase-to-platelet ratio index; FIB-4: fibrosis index based on the 4 factors.