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

Phenotypic and metabolomic characteristics of mouse models of metabolic associated steatohepatitis

BACKGROUND

Metabolic associated steatohepatitis (MASH) is metabolic disease that may progress to cirrhosis and hepatocellular carcinoma. Mouse models of diet-induced MASH, which is characterized by the high levels of fats, sugars, and cholesterol in diets, are commonly used in research. However, mouse models accurately reflecting the progression of MASH in humans remain to be established. Studies have explored the potential use of serological metabolites as biomarkers of MASH severity in relation to human MASH.

METHODS

We performed a comparative analysis of three mouse models of diet-induced MASH in terms of phenotypic and metabolomic characteristics; MASH was induced using different diets: a high-fat diet; a Western diet; and a high-fat, high-cholesterol diet. Liver cirrhosis was diagnosed using standard clinical approaches (e.g., METAVIR score, hyaluronan level, and collagen deposition level). Mouse serum samples were subjected to nuclear magnetic resonance spectroscopy-based metabolomic profiling followed by bioinformatic analyses. Metabolomic analysis of a retrospective cohort of patients with hepatocellular carcinoma was performed; the corresponding cirrhosis scores were also evaluated.

RESULTS

Using clinically relevant quantitative diagnostic methods, the severity of MASH was evaluated. Regarding metabolomics, the number of lipoprotein metabolites increased with both diet and MASH progression. Notably, the levels of very low-density lipoprotein (VLDL) and low-density lipoprotein (LDL) significantly increased with fibrosis progression. During the development of diet-induced MASH in mice, the strongest upregulation of expression was noted for VLDL receptor. Metabolomic analysis of a retrospective cohort of patients with cirrhosis indicated lipoproteins (e.g., VLDL and LDL) as predominant biomarkers of cirrhosis.

CONCLUSIONS

Our findings provide insight into the pathophysiology and metabolomics of experimental MASH and its relevance to human MASH. The observed upregulation of lipoprotein expression reveals a feedforward mechanism for MASH development that may be targeted for the development of noninvasive diagnosis.

Zinc-glutathione in Chinese Baijiu prevents alcohol-associated liver injury

Zinc depletion is associated with alcohol-associated liver injury. We tested the hypothesis that increasing zinc availability along with alcohol consumption prevents alcohol-associated liver injury. Zinc-glutathione (ZnGSH) was synthesized and directly added to Chinese Baijiu. Mice were administered a single gastric dose of 6 g/kg ethanol in Chinese Baijiu with or without ZnGSH. ZnGSH in Chinese Baijiu did not change the likeness of the drinkers but significantly reduced the recovery time from drunkenness along with elimination of high-dose mortality. ZnGSH in Chinese Baijiu decreased serum AST and ALT, suppressed steatosis and necrosis, and increased zinc and GSH concentrations in the liver. It also increased alcohol dehydrogenase and aldehyde dehydrogenase in the liver, stomach, and intestine and reduced acetaldehyde in the liver. Thus, ZnGSH in Chinese Baijiu prevents alcohol-associated liver injury by increasing alcohol metabolism timely with alcohol consumption, providing an alternative approach to the management of alcohol-associated drinking.

Selective suppression of M1 macrophages is involved in zinc inhibition of liver fibrosis in mice

Zinc deficiency is common in the liver of patients with chronic liver disease. Zinc supplementation suppresses the progression of liver fibrosis induced by bile duct ligation (BDL) in mice. The present study was undertaken to specifically investigate a possible mechanism by which zinc plays this role in the liver. Kunming mice were subjected to BDL for 4 weeks to induce liver fibrosis, and concomitantly treated with zinc sulfite or saline as control by gavage once a day. The results showed that zinc supplementation significantly suppressed liver fibrosis and inflammation along with inhibition of hepatic stellate cells activation induced by BDL. These inhibitory effects were accompanied by the reduction of collagen deposition and a significant reduction of macrophage infiltration affected livers. Importantly, zinc selectively inhibited M1 macrophage polarization and M1-related inflammatory cytokines. This inhibitory effect was further confirmed by the reduction of relevant biomarkers of M1 macrophages including inducible NO synthase (iNOS), monocyte chemotactic protein-1 (MCP-1/CCL2), and tumor necrosis factor-α in the zinc supplemented BDL livers. In addition, zinc inhibition of M1 macrophages was associated with a decrease of Notch1 expression. Taken together, these data indicated that zinc supplementation inhibited liver inflammation and fibrosis in BDL mice through selective suppression of M1 macrophages, which is associated with inhibition of Notch1 pathway in M1 macrophage polarization.

Hepatoprotective effect of linagliptin against liver fibrosis induced by carbon tetrachloride in mice

The current study aimed to investigate linagliptin for its potential role in the prevention of liver fibrosis progression. Balb-C mice were randomly allocated into five groups (10 each): (i) control; (ii) mice were injected intraperitoneally with 50 μL carbon tetrachloride (CCl₄) in corn oil in a dose of 0.6 μL/g three times per week for four weeks; (iii) linagliptin was administered orally in a daily dose of 10 mg/kg simultaneously with CCl₄; (iv) silymarin was administered orally in a daily dose of 200 mg/kg concomitantly with CCl₄; and (v) only linagliptin was administered. Hepatic injury was manifested in the CCl₄ group by elevation of biochemical parameters (alanine aminotransferase (ALT), aspartate aminotransferase (AST), alkaline phosphatase (ALP)), and hepatic fibrosis was evident histopathologically by increased METAVIR score and immunostaining expression of alpha-smooth muscle actin (α-SMA), as well as increased liver tissue oxidative stress parameters, transforming growth factor-β1 (TGF-β1), and mammalian target of rapamycin (mTOR). Linagliptin was able to stop the progression of liver fibrosis, evident histopathologically with reduced METAVIR score and α-SMA expression. The possible mechanism may be via suppression of oxidative stress, TGF-β1, and mTOR, which was associated with improvement of serum biochemical parameters ALT and AST. In conclusion, linagliptin might help to protect the liver against persistent injury-related consequences.

Common Bile Duct Ligation as Model for Secondary Biliary Cirrhosis

Cholestatic liver disease covers a range of biliary disorders marked by an impaired bile duct flow. Various conditions can result in bile obstruction including choledocholithiasis, surgical trauma, and autoimmune disorders. Cholestatic liver disease can be mild but generally progresses to more severe conditions with increased hepatobiliary injury, cholangitis, and ultimately liver fibrosis and cirrhosis. An extensively used experimental model to investigate the pathophysiology of biliary cirrhosis and potential novel therapies is the common bile duct ligation in mice and rats. Common bile duct ligation induces the different stages of cholestatic-induced liver disease being cholestasis, subsequently accompanied by inflammation and finally liver fibrosis and cirrhosis. In this protocol, an outline of the surgical procedures to conduct common bile duct ligation in mice is provided. The major steps include the isolation of the common bile duct, followed by ligation and dissection.

Application of a Simple Quantitative Assessment of Atherosclerotic Lesions in Freshly Isolated Aortas from Rabbits

Rabbits are widely used for the study of atherosclerosis; however, the lack of a unified and quantitative analysis of atheroma limits data interpretation and comparisons between laboratories. In this study, we applied a simple quantitative method, referred to as the oil red O (ORO) dye-eluting method, for analysis of atherosclerotic plaques in freshly isolated aortas. It employs ORO staining of the plaques followed by elution of the dye that is subjected to quantitative measurement. Atherosclerosis was induced in rabbits by feeding a 1% (w/w) high cholesterol diet for 4 or 12 weeks. Thoracic aortas were isolated and sufficiently stained by ORO. These dyes were easily and completely extracted by 100% ethanol and quantified by spectrophotometric measurement at 510 nm. A series of cross-sectional slices at 100-µm intervals were counterstained by elastic van Gieson. It was found that there was a highly positive correlation between the dye concentration and the amount of plaque tissue, determined as volume of plaques (regression coefficient r²: 0.8792, p < 0.001). The color equivalence of the dye content was expressed as µg/mm² of intimal aorta area to allow direct comparisons among aortas. The color equivalences of ORO content in rabbits fed 12 weeks were almost 5.0 times higher than those fed 4 weeks. Thus, this ORO dye-eluting method is useful for quantification of atherosclerotic plaques in aortas in rabbits, as well as other animal models.