Development Of Nonalcoholic Steatohepatitis Research Articles

275-LB: Mitochondrial Fission Factor Can Be a Key Factor in the Regulation of Hepatic Lipid Metabolism

Nonalcoholic fatty liver disease (NAFLD) develops into nonalcoholic steatohepatitis (NASH) when fat accumulates in the liver, leading to hepatocyte apoptosis, inflammation and fibrosis. No effective treatments for NASH have been established. Mitochondria are important organelles that play a central role in de novo lipogenesis and fatty acid β-oxidation. We have shown that mitochondrial fission is enhanced by short-term high-fat diet (HFD) loading, but is impaired by long-term. We speculated that mitochondrial fission inhibition is associated with the development of NASH and generated mice deletion of hepatocyte-specific mitochondrial fission factor (KO) mice. Conditioning HFD, KO mice showed inhibition of hepatocyte mitochondrial fission, increased ER stress and decreased triglyceride secretion from the liver. The hepatic triglyceride contents had significantly increased in KO mice compared to control (CONT), and histological analysis showed a marked increase in large lipid droplets (LDs). In addition to marked fat accumulation, hepatic apoptosis, inflammation and fibrosis were increased in the livers of KO mice, indicating the development of NASH. We noted that large LDs were increased in KO mice and added an additional analysis to determine how mitochondrial fission inhibition is involved in LDs formation in the liver. Oleic acid is a representative monounsaturated fatty acid that promotes LDs deposition in hepatocytes and is mildly cytotoxic by inducing ER stress and apoptosis. Loading primary cultured hepatocytes (PH) with oleic acid increased the number of smaller LDs in PH of CONT mice, whereas LDs in cells of KO mice became larger. Gene expression of Cidec, which acts on the fusion of LDs, was increased in the liver of KO mice, suggesting that inhibition of mitochondrial fission may induce the fusion of LDs and the enlargement of intracellular LDs in the liver. Further analysis is planned, as inhibition of mitochondrial fission may be involved in changes of LDs morphology. Disclosure Y. Takeichi: None. T. Miyazawa: None. Y. Ogawa: None.

1602-P: Galectin-3 Inhibition Protects ApoE Knockout Mice against Western Diet–Induced Nonalcoholic Steatohepatitis and Glucose Intolerance

Nonalcoholic Fatty Liver Disease represents a broad spectrum of histological abnormalities ranging from simple steatosis to nonalcoholic steatohepatitis (NASH), which may progress to cirrhosis or hepatocellular carcinoma. NASH is characterized by steatosis, hepatic inflammation, hepatocellular ballooning, and fibrosis. Therefore, the aim of this work was to evaluate the effect of modified citrus pectin (MCP), inhibitor of galectin-3, in ApoE KO mice fed a western diet (WD). ApoE KO mice were divided into 3 groups: standard diet-fed (SD) group, WD-fed group, and WD-fed + MCP-treated group (WD+MCP). WD-fed mice displayed increased hepatic triacylglycerides (TAG-290%), and plasma ALT (115%) and AST (130%) compared with SD group. MCP treatment decreased hepatic TAG (30%) in WD-fed mice, plasma ALT and AST were reverted. WD-fed mice also displayed increased hepatic collagen deposition (18%), and MCP treatment inhibited this increase. These results were similar with hydroxyproline concentration in liver. WD-fed mice showed an impaired glucose tolerance compared with SD-fed mice, while MCP treatment improved glucose tolerance in WD-fed mice. Also, WD-fed mice presented increased fasting insulin (140%) compared with SD-fed mice, and MCP treatment reverted this increase by 100%. Gene expression of F4/80 was increased by 76% in the WD group compared with SD group, however had not significant difference between WD+MCP and SD group. Gene expression of matrix metalloproteinase 2 was increased by 5-fold in WD group compared with SD group, while this increase was inhibited with MCP treatment. Also, it was observed an increase in JNK phosphorylation by 3-fold in WD group, and MCP treatment inhibited this increase. Taken together, we confirm WD-fed ApoE KO mice as a suitable experimental model of NASH, and the inhibition of galectin-3 by the treatment with MCP protects ApoE KO mice against the development of NASH and glucose intolerance. Disclosure L. Araujo: None. F. Sucupira: None. C.C.B. Dias: None. A. Amaral: None. J. Camporez: None. Funding São Paulo Research Foundation (FAPESP)

Through regulation of the SIRT1 pathway plant sterol ester of α-linolenic acid inhibits pyroptosis thereby attenuating the development of NASH in mice

Increasing evidence demonstrated that pyroptosis and subsequent inflammation played an important role in the pathological process of non-alcoholic steatohepatitis (NASH). Plant sterol ester of α-linolenic acid (PS-ALA) was beneficial for non-alcoholic fatty liver disease, but the underlying mechanisms are still not fully understood. This study aims to investigate whether PS-ALA can protect against proptosis via regulating SIRT1. Thirty male C57BL/6J mice were fed a normal diet, a high-fat and high-cholesterol diet (HFCD), or a HFCD supplemented with either 1.3%ALA, 2%PS, or 3.3% PS-ALA for 24 weeks. Hepatocytes were treated with oleic acid and cholesterol (OA/Cho) with or without PS-ALA. We found that PS-ALA ameliorated NASH in HFCD-fed mice. In addition, PS-ALA decreased the expression of NLRP3 and ASC and reduced the co-localization of NLRP3 and cleave-Caspase-1. Also, PS-ALA protected against pyroptosis as evidenced by decreased co-localization of GSDMD and propidium iodide (PI) positive cells. Mechanistically, we revealed that the inhibitory action of PS-ALA on the pyroptosis was mediated by SIRT1. This was demonstrated by the fact that silencing SIRT1 with small interfering RNA or inhibition of SIRT1 with its inhibitor abolished the inhibition effect of PS-ALA on the expression of NLRP3 and GSDMD cleavage. Collectively, the data from the present study reveals a novel mechanism that PS-ALA inhibits pyroptosis and it triggered inflammation via stimulating SIRT1, which provides new insights into the beneficial effect of PS-ALA on NASH.

Farnesyl diphosphate synthase exacerbates nonalcoholic steatohepatitis via the activation of AHR-CD36 axis.

Nonalcoholic steatohepatitis (NASH) has become a major concern that threatens human health worldwide. The underlying pathogenesis was crucial but remained poorly understood. Here, we found that the expression of hepatic farnesyl diphosphate synthase (FDPS) was increased in mice and patients with NASH. Elevated FDPS levels were positively correlated with NASH severity. Overexpression of FDPS in mice provoked increased lipid accumulation, inflammation, and fibrosis, while hepatic FDPS deficiency protected mice from NASH progression. Importantly, pharmacological inhibition of FDPS with clinically used alendronate remarkably attenuated NASH-associated phenotypes in mice. Mechanistically, we demonstrated that FDPS increased its downstream product farnesyl pyrophosphate levels, which could function as an aryl hydrocarbon receptor (AHR) agonist to upregulate the expression of fatty acid translocase CD36, to accelerate the development of NASH. Collectively, these findings suggest that FDPS exacerbates NASH via AHR-CD36 axis and identify FDPS as a promising target for NASH therapy.

Pharmacology of a Potent and Novel Inhibitor of the NOD-Like Receptor Pyrin Domain-Containing Protein 3 (NLRP3) Inflammasome that Attenuates Development of Nonalcoholic Steatohepatitis and Liver Fibrosis.

The NOD-like receptor pyrin domain-containing protein 3 (NLRP3) inflammasome is a multiprotein complex and component of the innate immune system that is activated by exogenous and endogenous danger signals to promote activation of caspase-1 and the maturation and release of the proinflammatory cytokines interleukin (IL)-1β and IL-18. Inappropriate activation of NLRP3 has been implicated in the pathophysiology of multiple inflammatory and autoimmune diseases, including cardiovascular disease, neurodegenerative diseases, and nonalcoholic steatohepatitis (NASH), thus increasing the clinical interest of this target. We describe in this study the preclinical pharmacologic, pharmacokinetic, and pharmacodynamic properties of a novel and highly specific NLRP3 inhibitor, JT001 (6,7-dihydro-5H-pyrazolo[5,1-b][1,3]oxazine-3-sulfonylurea). In cell-based assays, JT001 potently and selectively inhibited NLRP3 inflammasome assembly, resulting in the inhibition of cytokine release and the prevention of pyroptosis, a form of inflammatory cell death triggered by active caspase-1. Oral administration of JT001 to mice inhibited IL-1β production in peritoneal lavage fluid at plasma concentrations that correlated with mouse in vitro whole blood potency. Orally administered JT001 was effective in reducing hepatic inflammation in three different murine models, including the Nlrp3A350V /+CreT model of Muckle-Wells syndrome (MWS), a diet-induced obesity NASH model, and a choline-deficient diet-induced NASH model. Significant reductions in hepatic fibrosis and cell damage were also observed in the MWS and choline-deficient models. Our findings demonstrate that blockade of NLRP3 attenuates hepatic inflammation and fibrosis and support the use of JT001 to investigate the role of NLRP3 in other inflammatory disease models. SIGNIFICANCE STATEMENT: Persistent inflammasome activation is the consequence of inherited mutations of NLRP3 and results in the development of cryopyrin-associated periodic syndromes associated with severe systemic inflammation. NLRP3 is also upregulated in nonalcoholic steatohepatitis, a metabolic chronic liver disease currently missing a cure. Selective and potent inhibitors of NLRP3 hold great promise and have the potential to overcome an urgent unmet need.

WED-428 - In vitro investigation of the role of adipocyte-derived exosomes in the development of non-alcoholic steatohepatitis

WED-428 - In vitro investigation of the role of adipocyte-derived exosomes in the development of non-alcoholic steatohepatitis

Inhibition of microRNA-33b in humanized mice ameliorates nonalcoholic steatohepatitis.

Nonalcoholic steatohepatitis (NASH) can lead to cirrhosis and hepatocellular carcinoma in their advanced stages; however, there are currently no approved therapies. Here, we show that microRNA (miR)-33b in hepatocytes is critical for the development of NASH. miR-33b is located in the intron of sterol regulatory element-binding transcription factor 1 and is abundantly expressed in humans, but absent in rodents. miR-33b knock-in (KI) mice, which have a miR-33b sequence in the same intron of sterol regulatory element-binding transcription factor 1 as humans and express miR-33b similar to humans, exhibit NASH under high-fat diet feeding. This condition is ameliorated by hepatocyte-specific miR-33b deficiency but unaffected by macrophage-specific miR-33b deficiency. Anti-miR-33b oligonucleotide improves the phenotype of NASH in miR-33b KI mice fed a Gubra Amylin NASH diet, which induces miR-33b and worsens NASH more than a high-fat diet. Anti-miR-33b treatment reduces hepatic free cholesterol and triglyceride accumulation through up-regulation of the lipid metabolism-related target genes. Furthermore, it decreases the expression of fibrosis marker genes in cultured hepatic stellate cells. Thus, inhibition of miR-33b using nucleic acid medicine is a promising treatment for NASH.

Identification of ferroptosis-related genes in the progress of NASH.

Non-alcoholic steatohepatitis (NASH) is becoming more widespread, and some similarities exist between its etiology and ferroptosis. However, there are limited investigations on which ferroptosis-related genes (FRGs) are regulated in NASH and how to regulate them. We screened and validated the pivotal genes linked to ferroptosis in NASH to comprehend the function of ferroptosis in the development of NASH. Two mRNA expression data were obtained from the Gene Expression Omnibus (GEO) as the training set and validation set respectively. FRGs were downloaded from FerrDb. The candidate genes were obtained from the intersection between differentially expressed genes (DEGs) and FRGs, and further analyzed using the Gene Ontology (GO) and Kyoto Encyclopedia of Genes and Genomes (KEGG). The hub genes were identified by the protein-protein interaction (PPI) network and Cytoscape. Then, FRGs closely related to the severity of NASH were identified and further confirmed using the validation set and mouse models. Ultimately, based on these genes, a diagnostic model was established to differentiate NASH from normal tissues using another data set from GEO. A total of 327 FRGs in NASH were acquired and subjected to GSEA. And 42 candidate genes were attained by overlapping the 585 FRGs with 2823 DEGs, and enrichment analysis revealed that these genes were primarily engaged in the fatty acid metabolic, inflammatory response, and oxidative stress. A total of 10 hub genes (PTGS2、IL1B、IL6、NQO1、ZFP36、SIRT1、ATF3、CDKN1A、EGR1、NOX4) were then screened by PPI network. The association between the expression of 10 hub genes and the progress of NASH was subsequently evaluated by a training set and verified by a validation set and mouse models. CDKN1A was up-regulated along with the development of NASH while SIRT1 was negatively correlated with the course of the disease. And the diagnostic model based on CDKN1A and SIRT1 successfully distinguished NASH from normal samples. In summary, our findings provide a new approach for the diagnosis, prognosis, and treatment of NASH based on FRGs, while advancing our understanding of ferroptosis in NASH.

Dietary Long-Chain Fatty Acids Accelerate Metabolic Dysfunction in Guinea Pigs with Non-Alcoholic Steatohepatitis.

The composition of dietary fatty acids may be important for the development and progression of metabolic syndrome and non-alcoholic steatohepatitis (NASH). This study investigated the effect of two high-fat diets based on coconut oil, containing predominantly medium-chain fatty acids (MCFA), or cocoa butter, containing mainly long-chain fatty acids (LCFA), on glucose homeostasis and NASH in guinea pigs following 16 and 32 weeks of diet. At week 16, glucose intolerance was increased in the LCFA animals compared to the MCFA animals (p < 0.001), with both groups differing from the controls by week 32 (p < 0.0001), supported by increased hemoglobin A1c (p < 0.05). NASH was present in both high-fat groups from week 16, with advancing fibrosis appearing more progressive in the LCFA animals at week 16. In agreement, gene expression showed overall increased expression of NASH target genes in the LCFA animals compared to the MCFA animals at weeks 16 and 32 (p < 0.05 and p < 0.0001, respectively). The LCFA animals also displayed increased plasma uric acid at both time points (p < 0.05), a phenomenon linked to NASH in humans. In conclusion, this study reports that a diet high in LCFA promotes metabolic imbalance and may accelerate NASH-associated hepatic fibrosis. This highlights the importance of a critical evaluation of fatty acid composition when investigating NASH-associated endpoints.

Intestinal B cells license metabolic T-cell activation in NASH microbiota/antigen-independently and contribute to fibrosis by IgA-FcR signalling

The progression of non-alcoholic steatohepatitis (NASH) to fibrosis and hepatocellular carcinoma (HCC) is aggravated by auto-aggressive T cells. The gut-liver axis contributes to NASH, but the mechanisms involved and the consequences for NASH-induced fibrosis and liver cancer remain unknown. We investigated the role of gastrointestinal B cells in the development of NASH, fibrosis and NASH-induced HCC. C57BL/6J wild-type (WT), B cell-deficient and different immunoglobulin-deficient or transgenic mice were fed distinct NASH-inducing diets or standard chow for 6 or 12 months, whereafter NASH, fibrosis, and NASH-induced HCC were assessed and analysed. Specific pathogen-free/germ-free WT and μMT mice (containing B cells only in the gastrointestinal tract) were fed a choline-deficient high-fat diet, and treated with an anti-CD20 antibody, whereafter NASH and fibrosis were assessed. Tissue biopsy samples from patients with simple steatosis, NASH and cirrhosis were analysed to correlate the secretion of immunoglobulins to clinicopathological features. Flow cytometry, immunohistochemistry and single-cell RNA-sequencing analysis were performed in liver and gastrointestinal tissue to characterise immune cells in mice and humans. Activated intestinal B cells were increased in mouse and human NASH samples and licensed metabolic T-cell activation to induce NASH independently of antigen specificity and gut microbiota. Genetic or therapeutic depletion of systemic or gastrointestinal B cells prevented or reverted NASH and liver fibrosis. IgA secretion was necessary for fibrosis induction by activating CD11b+CCR2+F4/80+CD11c-FCGR1+ hepatic myeloid cells through an IgA-FcR signalling axis. Similarly, patients with NASH had increased numbers of activated intestinal B cells; additionally, we observed a positive correlation between IgA levels and activated FcRg+ hepatic myeloid cells, as well the extent of liver fibrosis. Intestinal B cells and the IgA-FcR signalling axis represent potential therapeutic targets for the treatment of NASH. There is currently no effective treatment for non-alcoholic steatohepatitis (NASH), which is associated with a substantial healthcare burden and is a growing risk factor for hepatocellular carcinoma (HCC). We have previously shown that NASH is an auto-aggressive condition aggravated, amongst others, by T cells. Therefore, we hypothesized that B cells might have a role in disease induction and progression. Our present work highlights that B cells have a dual role in NASH pathogenesis, being implicated in the activation of auto-aggressive T cells and the development of fibrosis via activation of monocyte-derived macrophages by secreted immunoglobulins (e.g., IgA). Furthermore, we show that the absence of B cells prevented HCC development. B cell-intrinsic signalling pathways, secreted immunoglobulins, and interactions of B cells with other immune cells are potential targets for combinatorial NASH therapies against inflammation and fibrosis.

A cross-sectional study on the prevalence rate and influencing factors of non-alcoholic fatty liver disease in overweight/obese children

To investigate the prevalence rate of non-alcoholic fatty liver disease (NAFLD) in overweight/obese children who visit a hospital, and to explore the influencing factors of NAFLD, in order to provide a basis for the prevention of NAFLD in overweight/obese children. Overweight/obese children who visited Hunan Children's Hospital from June 2019 to September 2021 were recruited. The prevalence rate of NAFLD was examined. Logistic regression analysis was used to explore the factors influencing the development of NAFLD [non-alcoholic fatty liver (NAFL) and non-alcoholic steatohepatitis (NASH)]. Receiver operating characteristic curve analysis was used to evaluate the predictive value of the influencing factors for NAFL and NASH. A total of 844 overweight/obese children aged 6-17 years were enrolled. The prevalence rate of NAFLD in overweight/obese children was 38.2% (322/844), among which the prevalence rates of NAFL and NASH were 28.8% (243/844) and 9.4% (79/844), respectively. Multivariate logistic regression analysis showed that the increase of waist-to-hip ratio (WHR) and low high-density lipoprotein cholesterol (HDL-C) were associated with the development of NAFL and NASH (P<0.05). The receiver operating characteristic curve analysis showed that the combined measurement of WHR and HDL-C had a predictive value for NAFL (area under the curve: 0.653, 95%CI: 0.613-0.694), and for NASH (area under the curve: 0.771, 95%CI: 0.723-0.819). The prevalence rate of NAFLD in overweight/obese children who visit a hospital is high. WHR and HDL-C are associated with the development of NAFLD and the combined measurement of WHR and HDL-C has a certain value for predicating the development of NAFLD.

The Role of Fucoxanthin in Non-Alcoholic Fatty Liver Disease.

Chronic liver disease (CLD) has emerged as a leading cause of human deaths. It caused 1.32 million deaths in 2017, which affected men more than women by a two-to-one ratio. There are various causes of CLD, including obesity, excessive alcohol consumption, and viral infection. Among them, non-alcoholic fatty liver disease (NAFLD), one of obesity-induced liver diseases, is the major cause, representing the cause of more than 50% of cases. Fucoxanthin, a carotenoid mainly found in brown seaweed, exhibits various biological activities against NAFLD. Its role in NAFLD appears in several mechanisms, such as inducing thermogenesis in mitochondrial homeostasis, altering lipid metabolism, and promoting anti-inflammatory and anti-oxidant activities. The corresponding altered signaling pathways are the β3-adorenarine receptor (β3Ad), proliferator-activated receptor gamma coactivator (PGC-1), adenosine monophosphate-activated protein kinase (AMPK), peroxisome proliferator-activated receptor (PPAR), sterol regulatory element binding protein (SREBP), nuclear factor kappa B (NF-κB), mitogen-activated protein kinase (MAPK), protein kinase B (AKT), SMAD2/3, and P13K/Akt pathways. Fucoxanthin also exhibits anti-fibrogenic activity that prevents non-alcoholic steatohepatitis (NASH) development.

Lipid-associated macrophages infiltration is associated with cardiac remodeling in a NASH

Non-alcoholic steatohepatitis (NASH) refers to a fatty liver with lobular inflammation that can progress to liver fibrosis. Although a statistical association between NASH and cardiovascular disease has been demonstrated in epidemiological studies, the nature of the links between liver disease and cardiac remodeling remains to be established. We hypothesize that alterations in circulating and tissue-resident immune cells contribute to inappropriate cardiac remodeling during the development of NASH. We explore a cohort of patients candidates for cardiac surgery (POMI-AF – NCT03376165) comparing liver status and myocardial immune profile. We characterized the structural remodeling and contractile dysfunction using transthoracic echocardiogram (TTE) and histology in a diet-induced mouse model of NASH. Leukocyte infiltration in the mice heart is explored using flow cytometry and single cell RNA sequencing (scRNAseq) analysis. The specific role of the liver is studied using hepatocyte-PPARα KO mice under NASH-diet. In human myocardium, patients with high risk of NASH with fibrosis had an increased number of M2-like macrophages compared to control patients. In our NASH-diet mice, we showed left ventricular hypertrophy, dilated left ventricle and an impaired diastolic function. We also found more ventricular fibrosis and increased cardiomyocyte area. Using scRNAseq, we identified an increased expression of the pro-fibrotic marker Galectin-3 by pro-inflammatory macrophages, and finally we identified an enriched “lipid-associated Ly6C- TREML4+ myeloid cells” cluster within the heart of NASH mice. This subpopulation was also enriched in the blood of hepatocyte-PPARα KO mice after 24 weeks of NASH diet. Using a translational approach, we here describe an association between NASH and altered cardiac macrophages. Although fibrosis can be partially explained by the expression of Galectin-3 by macrophages, the potential involvement of lipid-associated myeloid cells in cardiac hypertrophy remains to be established. As macrophages are implicated in several cardiac remodeling etiologies, our new results could explain the adverse remodeling observed in NASH.

Hepatic regulatory T-cells promote colorectal liver metastasis in NASH

Abstract Background: Non-alcoholic steatohepatitis (NASH), a progressive inflammatory form of NAFLD, underlies an extremely versatile and dynamic inflammatory microenvironment along with aberrant metabolism and ongoing liver regeneration. Regulatory T cells (Tregs), as essential immune regulatory cells, are critical for the inhibition of tumor-promoting inflammation and cancer cell escape. Our recent study found that Tregs were selectively increased in both mouse models and patients with NAFLD, which promotes us to study the role of Tregs in NASH-HCC. However, the role of Tregs in the development of hepatic metastasis in NASH liver remains unknown. Methods: A Western diet mouse model and the STAM mouse model were utilized for NASH development. MC38 murine colorectal tumor cells were injected via portal vein at 12 weeks of feeding or orthotopically injected into cecum subserosa. Tumor development will be determined 3 or 4 weeks after injection. Depletion of Tregs by FoxP3-DTR mice or CD25 antibody treatment. Transcriptomic profiling of leucocytes in hepatic immune microenvironment was determined by scRNA-seq. Results: There is a positive correlation between increased Tregs and hepatic tumor growth in NASH liver. Depleting Tregs inhibits the development of hepatic metastasis in NASH liver compared with control liver. NASH development led to a significant transcriptomic shift in hepatic immune cells, such as Kupffer cells, Tregs and MDSCs. Blocking the interaction of Tregs and PMN-MDSCs in the TME prevents tumor growth in the NASH liver. Conclusions: Tregs can suppress immunosurveillance in the premalignant stages of NASH. Therapies targeting Tregs could offer a potential strategy for preventing hepatic metastasis in patients with NASH. RO1GM137203

Elevated Serum Alpha-fetoprotein Levels in Non-alcoholic Steatohepatitis: Possible Molecular Mechanisms and Potential Clinical Significance

With the improvement of living standards in recent years, up to 90% of obese patients have nonalcoholic fatty liver disease (NAFLD). The number of nonalcoholic steatohepatitis (NASH)-related deaths will gradually increase, and NASH is expected to be the most common cause of liver-related deaths in the future. Therefore, there is an urgent need to find effective and reliable serum biomarkers to distinguish simple hepatic steatosis (SS) from NASH. Liver cell regeneration, oxidative stress-induced DNA methylation, and biliary epithelial cell proliferation were reported to increase serum alpha-fetoprotein (AFP) levels. AFP has long been used as a tool to monitor liver cancer. However, the function of AFP in NAFLD, especially NASH, has not been clarified. Moreover, whether an elevated AFP level indicates the occurrence of NASH or serves as a serum biomarker remains to be elucidated. The miRNA-122 pathway, DNA methylation and DNA damage, and activation of resident stem cells and/or progenitor cells in the liver, as well as necrosis, regeneration, and repair of liver cells, may contribute to slight increases in AFP levels in the development of NASH in patients with NAFLD. Furthermore, mildly elevated AFP levels may indicate the development of NASH. This review explores the role of elevated AFP levels in the development of NASH, with a specific focus on the underlying molecular mechanisms and the clinical significance.

Low-Dose Acetylsalicylic Acid and Mitochondria-Targeted Antioxidant Mitoquinone Attenuate Non-Alcoholic Steatohepatitis in Mice.

Non-alcoholic fatty liver disease (NAFLD) is the most common chronic liver disease. NAFLD can evolve from simple fatty liver to non-alcoholic steatohepatitis (NASH), and ultimately, to cirrhosis. Inflammation and oxidative stress, promoted by mitochondrial dysfunction, play a crucial role in the onset and development of NASH. To date, no therapy has been approved for NAFLD and NASH. The aim of this study is to evaluate if the anti-inflammatory activity of acetylsalicylic acid (ASA) and the mitochondria-targeted antioxidant effect of mitoquinone could hinder the progression of non-alcoholic steatohepatitis. In mice, fatty liver was induced through the administration of a deficient in methionine and choline and rich in fat diet. Two experimental groups were treated orally with ASA or mitoquinone. Histopathologic evaluation of steatosis and inflammation was performed; the hepatic expression of genes associated with inflammation, oxidative stress, and fibrosis was evaluated; the protein expression of IL-10, cyclooxygenase 2, superoxide dismutase 1, and glutathione peroxidase 1 in the liver was analyzed; a quantitative analysis of 15-epi-lipoxin A4 in liver homogenates was performed. Mitoquinone and ASA significantly reduced liver steatosis and inflammation by decreasing the expression of TNFα, IL-6, Serpinb3, and cyclooxygenase 1 and 2 and restoring the anti-inflammatory IL-10. Treatment with mitoquinone and ASA increased the gene and protein expression of antioxidants, i.e., catalase, superoxide dismutase 1, and glutathione peroxidase 1, and decreased the expression of profibrogenic genes. ASA normalized the levels of 15-epi-Lipoxin A4. In mice fed with a deficient in methionine and choline and rich in fat diet, mitoquinone and ASA reduce steatosis and necroinflammation and may represent two effective novel strategies for the treatment of non-alcoholic steatohepatitis.

A TNFα/Miz1-positive feedback loop inhibits mitophagy in hepatocytes and propagates non-alcoholic steatohepatitis

Non-alcoholic steatohepatitis (NASH) is a chronic inflammatory disease that can further progress to cirrhosis and hepatocellular carcinoma. However, the key molecular mechanisms behind this process have not been clarified. We analyzed human NASH and normal liver tissue samples by RNA-sequencing and liquid chromatography-mass spectrometry, identifying hepatocyte cytosolic protein Myc-interacting zinc-finger protein 1 (Miz1) as a potential target in NASH progression. We established a Western diet+fructose-induced NASH model in hepatocyte-specific Miz1 knockout and adeno-associated virus type 8-overexpressing mice. Human NASH liver organoids were used to confirm the mechanism, and immunoprecipitation and mass spectrometry were used to detect proteins that could interact with Miz1. We demonstrate that Miz1 is reduced in hepatocytes in human NASH. Miz1 is shown to bind to peroxiredoxin 6 (PRDX6), retaining it in the cytosol, blocking its interaction with mitochondrial Parkin at Cys431, and inhibiting Parkin-mediated mitophagy. In NASH livers, loss of hepatocyte Miz1 results in PRDX6-mediated inhibition of mitophagy, increased dysfunctional mitochondria in hepatocytes, and production of proinflammatory cytokines, including TNFα, by hepatic macrophages. Crucially, the increased production of TNFα results in a further reduction in hepatocyte Miz1 by E3-ubiquitination. This produces a positive feedback loop of TNFα-mediated hepatocyte Miz1 degradation, resulting in PRDX6-mediated inhibition of hepatocyte mitophagy, with the accumulation of dysfunctional mitochondria in hepatocytes and increased macrophage TNFα production. Our study identified hepatocyte Miz1 as a suppressor of NASH progression via its role in mitophagy; we also identified a positive feedback loop by which TNFα production induces degradation of cytosolic Miz1, which inhibits mitophagy and thus leads to increased macrophage TNFα production. Interruption of this positive feedback loop could be a strategy to inhibit the progression of NASH. Non-alcoholic steatohepatitis (NASH) is a chronic inflammatory disease that can further develop into cirrhosis and hepatocellular carcinoma. However, the key molecular mechanism of this process has not been fully clarified. Herein, we identified a positive feedback loop of macrophage TNFα-mediated hepatocyte Miz1 degradation, resulting in PRDX6-mediated inhibition of hepatocyte mitophagy, aggravation of mitochondrial damage and increased macrophage TNFα production. Our findings not only provide mechanistic insight into NASH progression but also provide potential therapeutic targets for patients with NASH. Our human NASH liver organoid culture is therefore a useful platform for exploring treatment strategies for NASH development.

Dietary cholesterol drives the development of nonalcoholic steatohepatitis by altering gut microbiota mediated bile acid metabolism in high-fat diet fed mice

Nonalcoholic fatty liver disease (NAFLD) is the most widespread chronic liver disorder globally. Unraveling the pathogenesis of simple fatty liver to nonalcoholic steatohepatitis (NASH) has important clinical significance for improving the prognosis of NAFLD. Here, we explored the role of a high-fat diet alone or combined with high cholesterol in causing NASH progression. Our results demonstrated that high dietary cholesterol intakes accelerate the progression of spontaneous NAFLD and induces liver inflammation in mice. An elevation of hydrophobic unconjugated bile acids cholic acid (CA), deoxycholic acid (DCA), muricholic acid and chenodeoxycholic acid, was observed in high-fat and high-cholesterol diet fed mice. Full-length sequencing of the 16S rDNA gene of gut microbiota revealed a significant increase in the abundance of Bacteroides, Clostridium, and Lactobacillus that possess bile salt hydrolase activity. Furthermore, the relative abundance of these bacterial species was positively correlated with content of unconjugated bile acids in liver. Moreover, the expression of genes related to bile acid reabsorption (organic anion-transporting polypeptides, Na+-taurocholic acid cotransporting polypeptide, apical sodium dependent bile acid transporter and organic solute transporter β) was found to be increased in mice with a high-cholesterol diet. Lastly, we observed that hydrophobic bile acids CA and DCA induce an inflammatory response in free fatty acids-induced steatotic HepG2 cells. In conclusion, high dietary cholesterol promotes the development of NASH by altering gut microbiota composition and abundance and thereby influencing with bile acid metabolism.

Expansion of macrophage and liver sinusoidal endothelial cell subpopulations during non-alcoholic steatohepatitis progression

Liver non-parenchymal cells (NPCs) play a critical role in the progression of non-alcoholic steatohepatitis (NASH). We aimed to explore the heterogeneity of NPCs and identify NASH-specific subpopulations contributing to NASH progression. Through single-cell RNA sequencing, we uncovered a proinflammatory subpopulation of Itgadhi/Fcrl5hi macrophages with potential function of modulating macrophage accumulation and promoting NASH development. We also identified subpopulations of Egr1hi and Ly6ahi liver sinusoidal endothelial cells (LSECs), which might participate in pathological angiogenesis and inflammation regulation. The Itgadhi/Fcrl5hi macrophages, Egr1hi LSECs, and Ly6ahi LSECs emerged in the early stage and expanded significantly along with pathological progression of liver injury during NASH. Cell-cell interactions between hepatic stellate cells (HSCs) and Itgadhi/Fcrl5hi macrophages, Egr1hi LSECs or Ly6ahi LSECs were enhanced in NASH liver. Our results revealed that expansion of Itgadhi/Fcrl5hi macrophages, Egr1hi LSECs or Ly6ahi LSECs was strongly associated with NASH severity, suggesting these subpopulations might be involved in NASH progression.

Abstract 2869: The role of regulatory T cells in NASH-mediated HCC development

Abstract Objective Non-alcoholic fatty liver disease (NAFLD) is the most common liver disease, ranging from simple steatosis to an advanced form of non-alcoholic steatohepatitis (NASH) without effective treatment. NASH can progress to liver cirrhosis and hepatocellular carcinoma (HCC) in association with increased production of liver-resident regulatory T cells (Treg). This study aims to identify the role of Tregs in NASH-driven HCC development. Methods Wild-type C57BL/6 mice were fed with a choline-low high-fat high-sugar diet (CL-HFS), which recapitulates the Western-pattern diet, to induce NASH, then received transplantation of oncogenic hepatocytes by intrasplenic injection to induce an orthotopic HCC. Wild-type mice fed with a normal diet were used for control. Hepatic immune cell profiling was characterized by flow cytometry to identify the cellular basis mediating CL-HFS-induced NASH. The metagenomic assay was applied to identify NASH-relevant gut microbiota in the liver tissue. Results CL-HFS caused successful development of NASH and liver fibrosis in wild-type mice. Fast orthotopic tumor growth was detected in NASH-bearing mice compared to wild-type mice. Strongly positive staining of glypican 3 (GPC3), increased frequency of Tregs, and increased expression of Col1α1, Col4α1, and α-SMA were detected in livers and tumors from NASH-bearing mice compared to wild-type mice by IHC and flow cytometry. Metagenomic assay detected the lipid-producing bacterial genus Bacillus in NASH liver, which was demonstrated to increase the frequency of Tregs in healthy spleen cells. Conclusion CL-HFS-caused NASH promotes HCC growth likely by increasing liver-resident Tregs and liver-infiltrating Bacillus. Keywords: Non-alcoholic fatty liver disease (NAFLD), Non-alcoholic steatohepatitis (NASH), choline-low high-fat high-sugar diet (CL-HFS), regulatory T cells (Tregs), Bacillus, hepatocellular carcinoma (HCC). Citation Format: Ming Yang, Eric T. Kimchi, Kevin F. Staveley-O’Carroll, Guangfu Li. The role of regulatory T cells in NASH-mediated HCC development [abstract]. In: Proceedings of the American Association for Cancer Research Annual Meeting 2023; Part 1 (Regular and Invited Abstracts); 2023 Apr 14-19; Orlando, FL. Philadelphia (PA): AACR; Cancer Res 2023;83(7_Suppl):Abstract nr 2869.