Semaglutide Improves Liver Steatosis and De Novo Lipogenesis Markers in Obese and Type-2-Diabetic Mice with Metabolic-Dysfunction-Associated Steatotic Liver Disease

Abstract

Metabolic-dysfunction-associated steatotic liver disease (MASLD) is a prevalent clinical condition associated with elevated morbidity and mortality rates. Patients with MASLD treated with semaglutide, a glucagon-like peptide-1 receptor agonist, demonstrate improvement in terms of liver damage. However, the mechanisms underlaying this beneficial effect are not yet fully elucidated. We investigated the efficacy of semaglutide in halting MASLD progression using a genetic mouse model of diabesity. Leptin-receptor-deficient mice with obesity and diabetes (BKS db/db) were either untreated or administered with semaglutide for 11 weeks. Changes in food and water intake, body weight and glycemia were monitored throughout the study. Body fat composition was assessed by dual-energy X-ray absorptiometry. Upon sacrifice, serum biochemical parameters, liver morphology, lipidomic profile and liver-lipid-related pathways were evaluated. The semaglutide-treated mice exhibited lower levels of glycemia, body weight, serum markers of liver dysfunction and total and percentage of fat mass compared to untreated db/db mice without a significant reduction in food intake. Histologically, semaglutide reduced hepatic steatosis, hepatocellular ballooning and intrahepatic triglycerides. Furthermore, the treatment ameliorated the hepatic expression of de novo lipogenesis markers and modified lipid composition by increasing the amount of polyunsaturated fatty acids. The administration of semaglutide to leptin-receptor-deficient, hyperphagic and diabetic mice resulted in the amelioration of MASLD, likely independently of daily caloric intake, suggesting a direct effect of semaglutide on the liver through modulation of the lipid profile.

Keywords: GLP1 receptor agonists; diabetes; insulin resistance; obesity; semaglutide; steatosis.

Figure 1

Food and water intake consumption, glycemia and body weight and body composition monitoring. Food (A) and water intake (B) between 12–23 weeks, non-fasting glycemia (C) and body weight (D) between 16–23 weeks in BKS WT (Blue), BKS db/db untreated (Red) and treated-with-semaglutide (Black)(25 μg/kg/week for 2 weeks followed by 100 μg/kg/week for 9 weeks) groups. The number under the semaglutide measurement indicates the percentage body weight reduction vs. BKS db/db. Analysis of lean mass (E), fat mass (F), total tissue (G), % fat (H) and representative images of DXA scanning (I) in the experimental model. Data are shown as scatter dot plots and mean ± SEM of each group (n = 6–8 mice/group); * p < 0.05, ** p < 0.01 and *** p < 0.0001 vs. BKS db/db.

Figure 2

Liver histopathological changes in the experimental model. Representative images (100× magnification) of hematoxylin–eosin staining (A) and oil red O staining (B) in liver samples from BKS WT, untreated BKS db/db and semaglutide-treated BKS db/db mice (BKS db/db + semaglutide, treated with an induction dose of 25 μg/kg/week for 2 weeks followed by 100 μg/kg/week for 9 weeks). (C) Quantification of NAFLD activity score (total NAS) and its histopathological characteristics: steatosis (D), hepatocellular ballooning (E) and lobular inflammation (F). (G) Quantification of positive oil red O staining. (H) Quantification of liver TGs by colorimetric kit. Data are shown as scatter dot plots and mean ± SEM of each group (n = 6–8 mice/group); * p < 0.05, ** p < 0.01 and *** p < 0.001 vs. BKS db/db.

Figure 3

Lipid composition in liver at 23 weeks. Analysis of fatty acids in liver TG fractions by gas chromatography/electron ionization mass spectrometry (GC-MS). Concentrations of de novo lipogenesis markers (A) and omega-3 polyunsaturated fatty acids (PUFAs) (B). (C) Hierarchical clustering based on liver lipid composition showing the upregulated (dark brown) and downregulated (dark blue) lipids in each experimental group. The semaglutide group was treated with an induction dose of 25 μg/kg/week for 2 weeks followed by 100 μg/kg/week for 9 weeks. Data are shown as box plots and mean ± SEM of each group (n = 5–8 mice/group); ** p < 0.01 and *** p < 0.001 vs. BKS db/db. Abbreviations: DNL: de novo lipogenesis.

Figure 4

Gene and protein expression of markers related to hepatic lipid metabolism. RNA expression analysis of genes involved in fatty acid uptake (CD36, Slc27a2) (A), de novo lipogenesis (Acaca, Fasn, Scd1) (B), fatty acid efflux (Abca1, Abcg1) (C) and transcription factors (Srebf1, Pparg) (D). The qPCR values were normalized by 18S rRNA and expressed as fold increases compared to BKS WT group. (E) Protein expression of lipogenic enzymes was evaluated by Western blot. Fold-change levels of proteins normalized by β-Actin and images of their respective Western blot. The semaglutide group was treated with an induction dose of 25 μg/kg/week for 2 weeks followed by 100 μg/kg/week for 9 weeks. Data are shown as box plots and mean ± SEM of each group (n = 6–10 mice/group); * p < 0.05 and *** p < 0.01 vs. BKS db/db. Abbreviations: FA: fatty acids; DNL: de novo lipogenesis.