Human translatability of the GAN diet-induced obese mouse model of non-alcoholic steatohepatitis

Abstract

Background: Animal models of non-alcoholic steatohepatitis (NASH) are important tools in preclinical research and drug discovery. Gubra-Amylin NASH (GAN) diet-induced obese (DIO) mice represent a model of fibrosing NASH. The present study directly assessed the clinical translatability of the model by head-to-head comparison of liver biopsy histological and transcriptome changes in GAN DIO-NASH mouse and human NASH patients.

Methods: C57Bl/6 J mice were fed chow or the GAN diet rich in saturated fat (40%), fructose (22%) and cholesterol (2%) for ≥38 weeks. Metabolic parameters as well as plasma and liver biomarkers were assessed. Liver biopsy histology and transcriptome signatures were compared to samples from human lean individuals and patients diagnosed with NASH.

Results: Liver lesions in GAN DIO-NASH mice showed similar morphological characteristics compared to the NASH patient validation set, including macrosteatosis, lobular inflammation, hepatocyte ballooning degeneration and periportal/perisinusoidal fibrosis. Histomorphometric analysis indicated comparable increases in markers of hepatic lipid accumulation, inflammation and collagen deposition in GAN DIO-NASH mice and NASH patient samples. Liver biopsies from GAN DIO-NASH mice and NASH patients showed comparable dynamics in several gene expression pathways involved in NASH pathogenesis. Consistent with the clinical features of NASH, GAN DIO-NASH mice demonstrated key components of the metabolic syndrome, including obesity and impaired glucose tolerance.

Conclusions: The GAN DIO-NASH mouse model demonstrates good clinical translatability with respect to the histopathological, transcriptional and metabolic aspects of the human disease, highlighting the suitability of the GAN DIO-NASH mouse model for identifying therapeutic targets and characterizing novel drug therapies for NASH.

Keywords: Diet-induced obesity; Glucose tolerance; Histomorphometry; Histopathology; Liver transcriptome; Mouse model; Non-alcoholic steatohepatitis; Translatability.

Fig. 1

Similar liver histopathological hallmarks in human NASH patients and GAN DIO-NASH mice. Upper panels: Representative photomicrographs of liver sections from human healthy normal-weight individual (a), NASH patient (b-e), chow-fed mouse (f) and GAN DIO-NASH mouse (g-j) stained with hematoxylin-eosin (HE, for evaluation of steatosis, inflammation and hepatocyte ballooning; a-d, f-i) or picro-Sirius Red (PSR, for evaluation of fibrosis; e, j). Arrows indicate inflammatory foci and ballooning hepatocytes, respectively. Lower panels: Histomorphometric quantitative assessment of liver lipid accumulation (HE staining), inflammation (galectin-3 immunostaining) and fibrosis (PSR staining) in human and mouse liver biopsy sections. *p < 0.05, **p < 0.01, ***p < 0.001 vs. corresponding control group, unpaired t-test

Fig. 2

Liver transcriptome changes in human NASH patients and GAN DIO-NASH mice. a Principal component analysis (PCA) of samples based on top 500 most variable gene expression levels. b Venn diagram depicting shared and separate differentially expressed genes (DEGs; false discovery rate < 0.05) in NASH patients and GAN DIO-NASH mice. c Comparison of significantly regulated disease-associated Reactome signalling pathways in NASH patients (n = 16) and GAN-DIO NASH mice (n = 25). Reactome signalling pathways are grouped according to biological pathway. Color gradients indicate significantly upregulated (red color) and downregulated (blue color) pathways compared to corresponding control group (chow-fed mice, n = 10; healthy normal-weight human individuals, n = 14)

Fig. 3

Regulation of disease-associated candidate genes in NASH patients and GAN DIO-NASH mice. a Disease-associated hepatic candidate genes, b Selected hepatic genes representing various drug targets for NASH. Color gradients indicate significantly upregulated (red color) and downregulated (blue color) gene expression in NASH patients (n = 16) and GAN DIO-NASH mice (n = 25) compared to corresponding control group (healthy normal-weight human individuals, n = 14; chow-fed mice, n = 10). Candidate genes are listed in Table S1

Fig. 4

GAN DIO-NASH mice develop characteristics of the metabolic syndrome. Terminal body weight (a), whole-body fat mass (b), whole-body lean mass (c), liver weight (d). **p < 0.01, ***p < 0.01 (unpaired t-test; chow-fed mice, n = 6–10; GAN DIO-NASH mice, n = 14–16). An intraperitoneal glucose tolerance test (ipGTT) was performed one week before termination. (e) Glucose excursion curves (− 60 to 180 min). ***p < 0.001 (repeated-measure two-way ANOVA; chow-fed mice, n = 10; GAN DIO-NASH mice, n = 15). Insert, AUC-glucose levels (0–180 min). **p < 0.01 (unpaired t-test). Terminal plasma insulin (f) and HOMA-IR (g). ***p < 0.01 (unpaired t-test; chow-fed mice, n = 10; GAN DIO-NASH mice, n = 15). Terminal plasma leptin (h), total cholesterol (i), triglycerides (j) and free fatty acids (k). **p < 0.01, ***p < 0.01 (unpaired t-test; chow-fed mice, n = 5–10; GAN DIO-NASH mice, n = 8–15)