Decreased Portal Circulation Augments Fibrosis and Ductular Reaction in Nonalcoholic Fatty Liver Disease in Mice

Effects of the subtypes of apolipoprotein E on immune inhibition and prognosis in patients with Hepatocellular Carcinoma

PURPOSE

To investigate whether prognosis of patients with hepatocellular carcinoma (HCC) is affected by the abundance and subgroups of myeloid-derived suppressor cells (MDSCs) as well as subtypes and expression of apolipoprotein E (apoE).

METHODS

31 HCC patients were divided into three groups according to blood total apoE level for detecting the abundance of immunoregulatory cells by flow cytometry. Tumour tissue microarrays from 360 HCC patients were evaluated about the abundance and subgroups of MDSCs and the expression of apoE2, apoE3, apoE4 by immunofluorescence staining and immunohistochemistry staining. Survival analysis by means of univariate, multivariate COX regression and Kaplan-Meier methods of the 360 patients was performed based on clinical and pathological examinations along with 10 years' follow-up data.

RESULTS

The lower apoE group presented higher abundance of MDSCs in the peripheral blood of HCC patients than higher apoE group. The abundance of monocyte-like MDSCs (M-MDSCs) was higher in the apoE low level group than high level group (p = 0.0399). Lower H-score of apoE2 (HR = 6.140, p = 0.00005) and higher H-score of apoE4 (HR = 7.001, p = 0.009) in tumour tissue were significantly associated with shorter overall survival (OS). The higher infiltration of polymorphonuclear granulocyte-like MDSCs (PMN-MDSCs, HR = 3.762, p = 0.000009) and smaller proportion of M-MDSCs of total cells (HR = 0.454, p = 0.006) in tumour tissue were independent risk factors for shorter recurrence-free survival (RFS).

CONCLUSION

The abundance of MDSCs in HCC patients' plasma negatively correlates with the level of apoE. The expression of apoE4 in HCC tissue indicated a poor prognosis while apoE2 might be a potential protective factor.

Aberrant differentiation and proliferation of hepatocytes in chronic liver injury and liver tumors

Chronic liver injury induces liver cirrhosis and facilitates hepatocarcinogenesis. However, the effects of this condition on hepatocyte proliferation and differentiation are unclear. We showed that rodent hepatocytes display a ductular phenotype when they are cultured within a collagenous matrix. This process involves transdifferentiation without the emergence of hepatoblastic features and is at least partially reversible. During the ductular reaction in chronic liver diseases with progressive fibrosis, some hepatocytes, especially those adjacent to ectopic ductules, demonstrate ductular transdifferentiation, but the majority of increased ductules originate from the existing bile ductular system that undergoes extensive remodeling. In chronic injury, hepatocyte proliferation is weak but sustained, and most regenerative nodules in liver cirrhosis are composed of clonally proliferating hepatocytes, suggesting that a small fraction of hepatocytes maintain their proliferative capacity in chronic injury. In mouse hepatocarcinogenesis models, hepatocytes activate the expression of various fetal/neonatal genes, indicating that these cells undergo dedifferentiation. Hepatocyte-specific somatic integration of various oncogenes in mice demonstrated that hepatocytes may be the cells of origin for a broad spectrum of liver tumors through transdifferentiation and dedifferentiation. In conclusion, the phenotypic plasticity and heterogeneity of mature hepatocytes are important for understanding the pathogenesis of chronic liver diseases and liver tumors.

Metabolic dysfunction-associated steatohepatitis treated by poly(ethylene glycol)-block-poly(cysteine) block copolymer-based self-assembling antioxidant nanoparticles

Non-alcoholic steatohepatitis (NASH), now known as metabolic dysfunction-associated steatohepatitis (MASH), involves oxidative stress caused by the overproduction of reactive oxygen species (ROS). Small-molecule antioxidants have not been approved for antioxidant chemotherapy because of severe adverse effects that collapse redox homeostasis, even in healthy tissues. To overcome these disadvantages, we have been developing poly(ethylene glycol)-block-poly(cysteine) (PEG-block-PCys)-based self-assembling polymer nanoparticles (NanoCyses), releasing Cys after in vivo degradation by endogenous enzymes, to obtain antioxidant effects without adverse effects. However, a comprehensive investigation of the effects of polymer design on therapeutic outcomes has not yet been conducted to develop our NanoCys system for antioxidant chemotherapy. In this study, we synthesized different poly(L-cysteine) (PCys) chains whose sulfanyl groups were protected by tert-butyl thiol (StBu) and butyryl (Bu) groups to change the reactivity of the side chains, affording NanoCys(SS) and NanoCys(Bu), respectively. To elucidate the importance of the polymer design, these NanoCyses were orally administered to MASH model mice as a model of oxidative stress-related diseases. Consequently, the acyl-protective NanoCys(Bu) significantly suppressed hepatic lipid accumulation and oxidative stress compared to NanoCys(SS). Furthermore, we substantiated that shorter PCys were much better than longer PCys for therapeutic outcomes and the effects related to the liberation properties of Cys from these nanoparticles. Owing to its antioxidant functions, NanoCyses also significantly attenuated hepatic inflammation and fibrosis in the MASH mouse model.

Portosystemic shunting prevents hepatocellular carcinoma in non-alcoholic fatty liver disease mouse models

BACKGROUND AND AIMS

Non-alcoholic fatty liver disease (NAFLD) is one of the leading cause of hepatocellular carcinoma (HCC). This association is supported by the translocation of bacteria products into the portal system, which acts on the liver through the gut-liver axis. We hypothesize that portosystemic shunting can disrupt this relationship, and prevent NAFLD-associated HCC.

METHODS

HCC carcinogenesis was tested in C57BL/6 mice fed a high-fat high-sucrose diet (HFD) and injected with diethylnitrosamine (DEN) at two weeks of age, and in double transgenic LAP-tTA and TRE-MYC (LAP-Myc) mice fed a methionine-choline-deficient diet. Portosystemic shunts were established by transposing the spleen to the sub-cutaneous tissue at eight weeks of age.

RESULTS

Spleen transposition led to a consistent deviation of part of the portal flow and a significant decrease in portal pressure. It was associated with a decrease in the number of HCC in both models. This effect was supported by the presence of less severe liver steatosis after 40 weeks, and lower expression levels of liver fatty acid synthase. Also, shunted mice exhibited lower liver oxygen levels, a key factor in preventing HCC as confirmed by the development of less HCCs in mice with hepatic artery ligation.

CONCLUSIONS

The present data show that portosystemic shunting prevents NAFLD-associated HCC, utilizing two independent mouse models. This effect is supported by the development of less steatosis, and a restored liver oxygen level. Portal pressure modulation and shunting deserve further exploration as potential prevention/treatment options for NAFLD and HCC.

Urine-based Detection of Congenital Portosystemic Shunt in C57BL/6 Mice

Sporadic occurrence of congenital portosystemic shunt (PSS) at a rate of ∼1 out of 10 among C57BL/6 J mice, which are widely used in biomedical research, results in aberrancies in serologic, metabolic, and physiologic parameters. Therefore, mice with PSS should be identified as outliers in research. Accordingly, we sought methods to, reliably and efficiently, identify PSS mice. Serum total bile acids ≥ 40 µm is a bona fide biomarker of PSS in mice but utility of this biomarker is limited by its cost and invasiveness, particularly if large numbers of mice are to be screened. This led us to investigate if assay of urine might serve as a simple, inexpensive, noninvasive means of PSS diagnosis. Metabolome profiling uncovered that Krebs cycle intermediates, that is, citrate, α-ketoglutarate, and fumarate, were strikingly and distinctly elevated in the urine of PSS mice. We leveraged the iron-chelating and pH-lowering properties of such metabolites as the basis for 3 urine-based PSS screening tests: urinary iron-chelation assay, pH strip test, and phenol red assay. Our findings demonstrate the feasibility of using these colorimetric assays, whereby their readout can be assessed by direct observation, to diagnose PSS in an inexpensive, rapid, and noninvasive manner. Application of our urinary PSS screening protocols can aid biomedical research by enabling stratification of PSS mice, which, at present, likely confound numerous ongoing studies.

Zonated quantification of immunohistochemistry in normal and steatotic livers

Immunohistochemical stains (IHC) reveal differences between liver lobule zones in health and disease, including nonalcoholic fatty liver disease (NAFLD). However, such differences are difficult to accurately quantify. In NAFLD, the presence of lipid vacuoles from macrovesicular steatosis further hampers interpretation by pathologists. To resolve this, we applied a zonal image analysis method to measure the distribution of hypoxia markers in the liver lobule of steatotic livers.The hypoxia marker pimonidazole was assessed with IHC in the livers of male C57BL/6 J mice on standard diet or choline-deficient L-amino acid-defined high-fat diet mimicking NAFLD. Another hypoxia marker, carbonic anhydrase IX, was evaluated by IHC in human liver tissue. Liver lobules were reconstructed in whole slide images, and staining positivity was quantified in different zones in hundreds of liver lobules. This method was able to quantify the physiological oxygen gradient along hepatic sinusoids in normal livers and panlobular spread of the hypoxia in NAFLD and to overcome the pronounced impact of macrovesicular steatosis on IHC. In a proof-of-concept study with an assessment of the parenchyma between centrilobular veins in human liver biopsies, carbonic anhydrase IX could be quantified correctly as well.The method of zonated quantification of IHC objectively quantifies the difference in zonal distribution of hypoxia markers (used as an example) between normal and NAFLD livers both in whole liver as well as in liver biopsy specimens. It constitutes a tool for liver pathologists to support visual interpretation and estimate the impact of steatosis on IHC results.

Enterohepatic Shunt-Driven Cholemia Predisposes to Liver Cancer

BACKGROUND & AIMS

Pathogenesis of hepatocellular carcinoma (HCC), which kills millions annually, is poorly understood. Identification of risk factors and modifiable determinants and mechanistic understanding of how they impact HCC are urgently needed.

METHODS

We sought early prognostic indicators of HCC in C57BL/6 mice, which we found were prone to developing this disease when fed a fermentable fiber-enriched diet. Such markers were used to phenotype and interrogate stages of HCC development. Their human relevance was tested using serum collected prospectively from an HCC/case-control cohort.

RESULTS

HCC proneness in mice was dictated by the presence of congenitally present portosystemic shunt (PSS), which resulted in markedly elevated serum bile acids (BAs). Approximately 10% of mice from various sources exhibited PSS/cholemia, but lacked an overt phenotype when fed standard chow. However, PSS/cholemic mice fed compositionally defined diets, developed BA- and cyclooxygenase-dependent liver injury, which was exacerbated and uniformly progressed to HCC when diets were enriched with the fermentable fiber inulin. Such progression to cholestatic HCC associated with exacerbated cholemia and an immunosuppressive milieu, both of which were required in that HCC was prevented by impeding BA biosynthesis or neutralizing interleukin-10 or programmed death protein 1. Analysis of human sera revealed that elevated BA was associated with future development of HCC.

CONCLUSIONS

PSS is relatively common in C57BL/6 mice and causes silent cholemia, which predisposes to liver injury and HCC, particularly when fed a fermentable fiber-enriched diet. Incidence of silent PSS/cholemia in humans awaits investigation. Regardless, measuring serum BA may aid HCC risk assessment, potentially alerting select individuals to consider dietary or BA interventions.

A maternal high-fat diet induces fetal origins of NASH-HCC in mice

Maternal overnutrition affects offspring susceptibility to nonalcoholic steatohepatitis (NASH). Male offspring from high-fat diet (HFD)-fed dams developed a severe form of NASH, leading to highly vascular tumor formation. The cancer/testis antigen HORMA domain containing protein 1 (HORMAD1), one of 146 upregulated differentially expressed genes in fetal livers from HFD-fed dams, was overexpressed with hypoxia-inducible factor 1 alpha (HIF-1alpha) in hepatoblasts and in NASH-based hepatocellular carcinoma (HCC) in offspring from HFD-fed dams at 15 weeks old. Hypoxia substantially increased Hormad1 expression in primary mouse hepatocytes. Despite the presence of three putative hypoxia response elements within the mouse Hormad1 gene, the Hif-1alpha siRNA only slightly decreased hypoxia-induced Hormad1 mRNA expression. In contrast, N-acetylcysteine, but not rotenone, inhibited hypoxia-induced Hormad1 expression, indicating its dependency on nonmitochondrial reactive oxygen species production. Synchrotron-based phase-contrast micro-CT of the fetuses from HFD-fed dams showed significant enlargement of the liver accompanied by a consistent size of the umbilical vein, which may cause hypoxia in the fetal liver. Based on these findings, a maternal HFD induces fetal origins of NASH/HCC via hypoxia, and HORMAD1 is a potential therapeutic target for NASH/HCC.