Epidemiology of nonalcoholic steatohepatitis and hepatocellular carcinoma

NAFLD-Related HCC: Focus on the Latest Relevant Preclinical Models

Hepatocellular carcinoma (HCC) is the most common type of primary liver cancer and one of the deadliest cancers worldwide. Despite extensive research, the biological mechanisms underlying HCC's development and progression remain only partially understood. Chronic overeating and/or sedentary-lifestyle-associated obesity, which promote Non-Alcoholic Fatty Liver Disease (NAFLD), have recently emerged as worrying risk factors for HCC. NAFLD is characterized by excessive hepatocellular lipid accumulation (steatosis) and affects one quarter of the world's population. Steatosis progresses in the more severe inflammatory form, Non-Alcoholic Steatohepatitis (NASH), potentially leading to HCC. The incidence of NASH is expected to increase by up to 56% over the next 10 years. Better diagnoses and the establishment of effective treatments for NAFLD and HCC will require improvements in our understanding of the fundamental mechanisms of the disease's development. This review describes the pathogenesis of NAFLD and the mechanisms underlying the transition from NAFL/NASH to HCC. We also discuss a selection of appropriate preclinical models of NAFLD for research, from cellular models such as liver-on-a-chip models to in vivo models, focusing particularly on mouse models of dietary NAFLD-HCC.

MKK4 Inhibitors-Recent Development Status and Therapeutic Potential

MKK4 (mitogen-activated protein kinase kinase 4; also referred to as MEK4) is a dual-specificity protein kinase that phosphorylates and regulates both JNK (c-Jun N-terminal kinase) and p38 MAPK (p38 mitogen-activated protein kinase) signaling pathways and therefore has a great impact on cell proliferation, differentiation and apoptosis. Overexpression of MKK4 has been associated with aggressive cancer types, including metastatic prostate and ovarian cancer and triple-negative breast cancer. In addition, MKK4 has been identified as a key regulator in liver regeneration. Therefore, MKK4 is a promising target both for cancer therapeutics and for the treatment of liver-associated diseases, offering an alternative to liver transplantation. The recent reports on new inhibitors, as well as the formation of a startup company investigating an inhibitor in clinical trials, show the importance and interest of MKK4 in drug discovery. In this review, we highlight the significance of MKK4 in cancer development and other diseases, as well as its unique role in liver regeneration. Furthermore, we present the most recent progress in MKK4 drug discovery and future challenges in the development of MKK4-targeting drugs.

Chemerin and Chemokine-like Receptor 1 Expression Are Associated with Hepatocellular Carcinoma Progression in European Patients

The chemoattractant protein chemerin is protective in experimental hepatocellular carcinoma (HCC), and high expression in HCC tissues of Asian patients was related to a favorable prognosis. Studies from Asia found reduced expression of chemerin in HCC compared to para-tumor tissues while our previous analysis observed the opposite. Aim of this study was to correlate chemerin expression in HCC tissues with disease severity of European patients Hepatocyte chemerin protein expression was assessed by immunohistochemistry in HCC tissue of 383 patients, and was low in 24%, moderate in 49% and high in 27%. High chemerin protein in the HCC tissues was related to the T stage, vessel invasion, histologic grade, Union for International Cancer Control (UICC) stage and tumor size. Chemokine-like receptor 1 (CMKLR1) is a functional chemerin receptor. CMKLR1 protein in hepatocytes was low expressed in HCC tissues of 36%, moderate in tissues of 32% and high in 32% of the HCCs. Tumor CMKLR1 was associated with the T stage, vessel invasion, histologic grade and UICC stage. Notably, sex-specific analysis revealed that associations of chemerin and CMKLR1 expression with HCC progression were significant in males but not in females. The tumor chemerin and CMKLR1 protein expression were not related to steatosis, inflammation and fibrosis grades. In summary, chemerin as well as CMKLR1 protein were related to disease severity of European HCC patients, and this was significant in males. This observation is in contrast to Asian patients where higher chemerin in the tumors was protective. Current analysis provides evidence for ethnicity and sex-related differences of tumor expressed chemerin and HCC severity.

Non-Parenchymal Cells and the Extracellular Matrix in Hepatocellular Carcinoma in Non-Alcoholic Fatty Liver Disease

Hepatocellular carcinoma (HCC) in the setting of non-alcoholic fatty liver disease (NAFLD)-related cirrhosis and even in the pre-cirrhotic state is increasing in incidence. NAFLD-related HCC has a poor clinical outcome as it is often advanced at diagnosis due to late diagnosis and systemic treatment response is poor due to reduced immune surveillance. Much of the focus of molecular research has been on the pathological changes in hepatocytes; however, immune cells, hepatic stellate cells, liver sinusoidal endothelial cells and the extracellular matrix may play important roles in the pathogenesis of NAFLD-related HCC as well. Here, we review the role of non-parenchymal cells in the liver in the pathogenesis of HCC in the context of NAFLD-NASH, with a particular focus on the innate and the adaptive immune system, fibrogenesis and angiogenesis. We review the key roles of macrophages, hepatic stellate cells (HSCs), T cells, natural killer (NK) cells, NKT cells and liver sinusoidal endothelial cells (LSECs) and the role of the extracellular matrix in hepatocarcinogenesis within the steatotic milieu.

Replication stress triggered by nucleotide pool imbalance drives DNA damage and cGAS-STING pathway activation in NAFLD

Non-alcoholic steatotic liver disease (NAFLD) is the most common cause of chronic liver disease worldwide. NAFLD has a major effect on the intrinsic proliferative properties of hepatocytes. Here, we investigated the mechanisms underlying the activation of DNA damage response during NAFLD. Proliferating mouse NAFLD hepatocytes harbor replication stress (RS) with an alteration of the replication fork's speed and activation of ATR pathway, which is sufficient to cause DNA breaks. Nucleotide pool imbalance occurring during NAFLD is the key driver of RS. Remarkably, DNA lesions drive cGAS/STING pathway activation, a major component of cells' intrinsic immune response. The translational significance of this study was reiterated by showing that lipid overload in proliferating HepaRG was sufficient to induce RS and nucleotide pool imbalance. Moreover, livers from NAFLD patients displayed nucleotide pathway deregulation and cGAS/STING gene alteration. Altogether, our findings shed light on the mechanisms by which damaged NAFLD hepatocytes might promote disease progression.

Differential progression of unhealthy diet-induced hepatocellular carcinoma in obese and non-obese mice

BACKGROUND

Non-alcoholic fatty liver disease (NAFLD) ranks first among liver diseases in Western countries. NAFLD is typically associated with obesity and diabetes, however it also develops in lean individuals without metabolic syndrome. The prevalence of lean NAFLD is 7 percent in the U.S. and 25-30 percent in some Asian countries. NAFLD starts with excess liver fat accumulation (NAFL), progresses to nonalcoholic steatohepatitis (NASH), cirrhosis and hepatocellular carcinoma (HCC). The pathogenesis of lean NASH-HCC and how it differs from obese NASH-HCC is not well understood.

METHODS

In this work, we generated a mouse model of lean and obese NASH-HCC using a choline deficient/high trans-fat/fructose/cholesterol diet and a choline supplemented/high trans-fat/fructose/cholesterol diet, respectively, to compare progression to NASH-HCC in lean versus obese mice. Comparisons were made at the organismal, histological, and molecular level by investigating fatty acid metabolism in the plasma of these mice.

RESULTS

Obese mice showed more pronounced glucose intolerance and insulin resistance, higher levels of plasma cholesterol and triglycerides, and higher penetrance of NASH compared to lean mice. Despite the abnormal metabolic profile of obese mice, male obese and lean mice developed HCC with similar penetrance (53.3% and 53.8%, respectively), albeit lean mice showed faster tumor progression as evidenced by the larger tumor size and lower HCC-free survival. None of the female lean mice developed HCC, while 50% of female obese mice developed HCC. Both groups of mice showed a reduction in plasma polyunsaturated fatty acids (PUFAs), however, the levels were higher towards the endpoint in obese mice compared to lean mice.

CONCLUSIONS

Unhealthy diet composition appears to drive progression to NASH-HCC rather than the organismal effects of obesity. PUFA levels may increase due to systemic inflammation in obese mice and act as suppressors of tumor progression, thus delaying HCC progression in obese mice compared to lean mice. These models could be used to further dissect the molecular pathogenesis of lean and obese NASH-HCC and address the mechanisms whereby PUFAs may be implicated in hepatocarcinogenesis.

Disentangling the Progression of Non-alcoholic Fatty Liver Disease in the Human Gut Microbiota

Gut microbiome dysbiosis has been known to be associated with all stages of non-alcoholic fatty liver disease (NAFLD), but questions remain about microbial profiles in progression and homogeneity across NAFLD stages. We performed a meta-analysis of three publicly shotgun datasets and built predictive models to determine diagnostic capacity. Here, we found consistently microbiome shifts across NAFLD stages, of which co-occurrence patterns and core sets of new biomarkers significantly correlated with NAFLD progression were identified. Machine learning models that are able to distinguish patients with any NAFLD stage from healthy controls remained predictive when applied to patients with other NAFLD stages, suggesting the homogeneity across stages once again. Focusing on species and metabolic pathways specifically associated with progressive stages, we found that increased toxic metabolites and decreased protection of butyrate and choline contributed to advanced NAFLD. We further built models discriminating one stage from the others with an average of 0.86 of area under the curve. In conclusion, this meta-analysis firmly establishes generalizable microbiome dysbiosis and predictive taxonomic and functional signatures as a basis for future diagnostics across NAFLD stages.

Chemerin Is Induced in Non-Alcoholic Fatty Liver Disease and Hepatitis B-Related Hepatocellular Carcinoma

Chemerin is protective in experimental models of hepatocellular carcinoma (HCC). Noteworthy, chemerin mRNA and protein were reduced in HCC tissues of Asian patients with mostly hepatitis B disease etiology. The current study nevertheless showed that chemerin protein was induced in tumor tissues of European HCC patients with non-alcoholic fatty liver disease (NAFLD) and patients with unclear disease etiology. A similar regulation was observed in hepatitis B virus (HBV), but not in hepatitis C virus (HCV), related HCC. The apparent discrepancy between the regulation of chemerin in HBV-HCC obtained from our study and recent reports led us to use the chemerin antibodies applied in the previous assays. These antibodies could not equally detect different chemerin isoforms, which were overexpressed in HepG2 cells. Higher chemerin protein in HCC was nevertheless confirmed by the use of all antibodies. Chemerin protein was low in Huh7 and PLC/PRF/5 cells whereas HepG2 and Hep3B cells had chemerin protein similar as primary human hepatocytes. Besides, the anti-tumor effects of retinoids in hepatocyte cell lines did not enclose upregulation of chemerin, which was initially discovered as a tazarotene induced protein in the skin. Finally, protein levels of the chemerin receptor, chemokine-like receptor 1 (CMKLR1), declined in non-viral, and tended to be lower in HBV-HCC tissues suggesting reduced chemerin activity in the tumors. To sum up, our work showed an opposite regulation of chemerin and CMKLR1 in NAFLD and HBV associated HCC. In HCV-HCC neither chemerin nor its receptor were changed in the tumor tissues. Current findings do not support a critical role of total chemerin protein levels in HCC of non-viral and viral etiology. Accordingly, tumor-localized chemerin protein was not associated with tumor-node-metastasis classification.

The Profile and Role of Tumor-infiltrating Lymphocytes in Hepatocellular Carcinoma: An Immunohistochemical Study

Hepatocellular carcinoma (HCC) is the most common primary malignant tumor of the liver. Tumor-infiltrating lymphocytes (TILs) are a class of cells that form the tumor microenvironment and thus have an effect on carcinogenesis. The aim of this study was to investigate the immunohistochemical expression of CD8, CD4, cytotoxic T lymphocyte-associated protein-4 (CTLA-4), and granzyme B in HCC and their correlation with clinicopathologic parameters and prognosis. This study was carried out on 112 cases of HCC. High percentage of CD8+ TILs was associated with large tumors and adjacent noncirrhotic liver. High percentage of CD4+ TILs and high CD4 to CD8 ratio were associated with nonviral etiology, low alpha fetoprotein, and direct acting antiviral treatment. High percentage of CTLA-4-positive TILs tended to be associated with high-grade HCC, while a high percentage of CTLA-4 in tumor cells was associated with multiple lesions and low tumor grade. High percentage of granzyme B+ TILs was associated with low grade, early stage, and absence of tumor recurrence. High CD4 percentage and high CD4/CD8 ratio affected patients' overall survival. There is a dynamic interaction between the different subsets of lymphocytes in the environment of HCC manifested by coparallel expression of CD4 and CD8 augmenting the expression of CTLA-4, and only CD8 augments the expression of granzyme B. This opens the gate for the beneficial role of immunotherapy in the management of HCC, reducing recurrence and improving survival.

Reduction of Polyunsaturated Fatty Acids with Tumor Progression in a Lean Non-Alcoholic Steatohepatitis-Associated Hepatocellular Carcinoma Mouse Model

Background and Aim: Non-alcoholic fatty liver disease (NAFLD) is the most common liver disease in Western countries. While obesity and diabetes are the hallmarks of NAFLD, it also develops in lean individuals in the absence of metabolic syndrome, with a prevalence of 7 percent in the U.S. and 25-30 percent in some Asian countries. NAFLD represents the spectrum of liver disease, starting with excess liver fat accumulation (NAFL) that can progress to nonalcoholic steatohepatitis (NASH), cirrhosis and ultimately hepatocellular carcinoma (HCC). To date, the pathogenesis of lean NASH-HCC is poorly understood and a mouse model is lacking. We aimed to develop a mouse model of lean NASH-HCC using a choline deficient and high trans-fat/sucrose/cholesterol diet to enable better understanding of its molecular pathogenesis. Methods: C57BL/6N mice were fed this diet starting at 4 weeks of age for 52 weeks and were compared to mice fed an isocaloric low fat control diet for the same duration. C57BL/6N mice were chosen instead of the C57BL/6J mice due to the high susceptibility of C57BL/6J mice to diet-induced obesity. The plasma and tumor fatty acid profile of these mice was also investigated. Results: Nearly 61% of the mice developed lean NASH-HCC. These mice showed reduction of plasma polyunsaturated fatty acids (PUFAs) (linolenic acids (α and γ, ω-3 and ω-6, respectively), eicosapentanoic acid (ω-3), docosahexanoic acid (ω-3), and linoleic acid (ω-6)) and increasing levels over time in mice with pre-malignant lesions. Conclusions: We developed a novel high penetrance diet-induced lean NASH-HCC mouse model. Plasma PUFA levels were reduced with tumor progression in parallel with reduced expression of genes controlling desaturase expression suggesting their potential use as biomarkers for lean NASH-HCC progression as well as chemopreventive molecules.

Gut microbiota and human NAFLD: disentangling microbial signatures from metabolic disorders

Gut microbiota dysbiosis has been repeatedly observed in obesity and type 2 diabetes mellitus, two metabolic diseases strongly intertwined with non-alcoholic fatty liver disease (NAFLD). Animal studies have demonstrated a potential causal role of gut microbiota in NAFLD. Human studies have started to describe microbiota alterations in NAFLD and have found a few consistent microbiome signatures discriminating healthy individuals from those with NAFLD, non-alcoholic steatohepatitis or cirrhosis. However, patients with NAFLD often present with obesity and/or insulin resistance and type 2 diabetes mellitus, and these metabolic confounding factors for dysbiosis have not always been considered. Patients with different NAFLD severity stages often present with heterogeneous lesions and variable demographic characteristics (including age, sex and ethnicity), which are known to affect the gut microbiome and have been overlooked in most studies. Finally, multiple gut microbiome sequencing tools and NAFLD diagnostic methods have been used across studies that could account for discrepant microbiome signatures. This Review provides a broad insight into microbiome signatures for human NAFLD and explores issues with disentangling these signatures from underlying metabolic disorders. More advanced metagenomics and multi-omics studies using system biology approaches are needed to improve microbiome biomarkers.

A Sweet Connection? Fructose's Role in Hepatocellular Carcinoma

Hepatocellular carcinoma is one of few cancer types that continues to grow in incidence and mortality worldwide. With the alarming increase in diabetes and obesity rates, the higher rates of hepatocellular carcinoma are a result of underlying non-alcoholic fatty liver disease. Many have attributed disease progression to an excess consumption of fructose sugar. Fructose has known toxic effects on the liver, including increased fatty acid production, increased oxidative stress, and insulin resistance. These effects have been linked to non-alcoholic fatty liver (NAFLD) disease and a progression to non-alcoholic steatohepatitis (NASH). While the literature suggests fructose may enhance liver cancer progression, the precise mechanisms in which fructose induces tumor formation remains largely unclear. In this review, we summarize the current understanding of fructose metabolism in liver disease and liver tumor development. Furthermore, we consider the latest knowledge of cancer cell metabolism and speculate on additional mechanisms of fructose metabolism in hepatocellular carcinoma.

Hepatocyte apoptosis is tumor promoting in murine nonalcoholic steatohepatitis

Nonalcoholic fatty liver disease is the most common chronic liver disease and may progress to nonalcoholic steatohepatitis (NASH) and hepatocellular carcinoma (HCC). The molecular determinants of this pathogenic progression, however, remain largely undefined. Since liver tumorigenesis is driven by apoptosis, we examined the effect of overt hepatocyte apoptosis in a mouse model of NASH using mice lacking myeloid cell leukemia 1 (Mcl1), a pro-survival member of the BCL-2 protein family. Hepatocyte-specific Mcl1 knockout (Mcl1^∆hep) mice and control littermates were fed chow or FFC (high saturated fat, fructose, and cholesterol) diet, which induces NASH, for 4 and 10 months. Thereafter, liver injury, inflammation, fibrosis, and tumor development were evaluated biochemically and histologically. Mcl1^∆hep mice fed with the FFC diet for 4 months displayed a marked increase in liver injury, hepatocyte apoptosis, hepatocyte proliferation, macrophage-associated liver inflammation, and pericellular fibrosis in contrast to chow-fed Mcl1^∆hep and FFC diet-fed Mcl1-expressing littermates. After 10 months of feeding, 78% of FFC diet-fed Mcl1^∆hep mice developed liver tumors compared to 38% of chow-fed mice of the same genotype. Tumors in FFC diet-fed Mcl1^∆hep mice were characterized by cytologic atypia, altered liver architecture, immunopositivity for glutamine synthetase, and histologically qualified as HCC. In conclusion, this study provides evidence that excessive hepatocyte apoptosis exacerbates the NASH phenotype with enhancement of tumorigenesis in mice.

Volumetric multicomponent T1ρ relaxation mapping of the human liver under free breathing at 3T

PURPOSE

To develop a 3D sequence for T_1ρ relaxation mapping using radial volumetric encoding (3D-T_1ρ -RAVE) and to evaluate the multi relaxation components in the liver of healthy controls and chronic liver disease (CLD) patients.

METHODS

Fat saturation and T_1ρ preparation modules were followed by a train of gradient-echo acquisitions and T₁ restoration delay. The series of T_1ρ -weighted images were fitted using mono-exponential, bi-exponential, and stretched-exponential models. The repeatability and reproducibility of the proposed technique were evaluated on National Institute of Standards and Technology phantom by calculating the coefficient of variation between test-retest scans on the same scanner and between two different 3T scanners, respectively. Mann-Whitney U-test was performed to assess differences in T_1ρ components among patients (n = 3) and a control group (n = 10).

RESULTS

The phantom study showed an error of 8.9% and 11.5% in mono T₂ relaxation time measurement relative to the reference on 2 different scanners. The coefficient of variation for test-retest scans performed on the same scanner was 5.7% and 2.4% for scans performed on 2 scanners. The comparison between healthy controls and CLD patients showed a significant difference (P < .05) in mono relaxation time (P = .002), stretched-exponential relaxation parameter (P = .04). The Akaike information criteria C criterion showed 2.53 ± 0.9% (2.3 ± 0.3% for CLD) of the voxels are bi-exponential while in 65.3 ± 5.8% (81.2 ± 0.06% for CLD) of the liver voxels, the stretched-exponential model was preferred.

CONCLUSION

The 3D-T_1ρ -RAVE sequence allows volumetric, multicomponent T_1ρ assessment of the liver during free breathing and can distinguish between healthy volunteers and CLD patients.

β-ionone inhibits nonalcoholic fatty liver disease and its association with hepatocarcinogenesis in male Wistar rats

Among the primary neoplasias that affect the liver, hepatocellular carcinoma (HCC) is the most frequent and the third leading cause of death related to cancer. Several risk factors predispose individuals to HCC such as nonalcoholic fatty liver disease (NAFLD), whose incidence has significantly increased worldwide. β-ionone (βI) isoprenoid is a known chemopreventive of hepatocarcinogenesis. However, the effects of this compound on NAFLD isolated or in association with hepatocarcinogenesis have not yet been evaluated. A high-fat emulsion administered for 6 weeks resulted in NAFLD in male rats, and oral treatment with βI during this period significantly attenuated its development. Moreover, the presence of NAFLD potentiated hepatocarcinogenesis induced by the resistant hepatocyte (RH) model in these animals by increasing the number and percentage of the liver section area occupied by placental glutathione S-transferase (GST-P)-positive persistent preneoplastic lesions (pPNLs), that are thought to evolve into HCC. This indicates that this NAFLD/RH protocol is suitable for studies of the influence of NAFLD on the HCC development. Therefore, here we also investigated the chemopreventive effect of βI under these two associated conditions. In this context, βI reduced the number and percentage of the liver section area occupied by pPNLs, as well as cell proliferation and the number of oval cells, which are considered potential targets for the development of HCC. Thus, βI presents not only a promising inhibitory effect on NAFLD isolated but also chemopreventive activity when it is associated with hepatocarcinogenesis.

Epidemiology of massive hepatocellular carcinoma in dogs: A 4-year retrospective study

Hepatocellular carcinoma (HCC) is the most common primary liver tumour in dogs. However, the clinical features and risk factors of HCC have not been confirmed. The objective of this study was to investigate the clinical features and risk factors for canine HCC. Medical records of 44 dogs diagnosed with HCC at Hokkaido University Veterinary Teaching Hospital between 2013 and 2017 were retrospectively reviewed. All dogs evaluated at the teaching hospital during the study period were used as the reference population for breed, age, sex predispositions or possible related factors for HCC, including concurrent disorders. Clinical characteristics of HCC were determined using propensity score matching analysis. The prevalence of HCC diagnosis was 0.96%. Multivariate analysis revealed that dogs diagnosed with HCC were significantly older (odds ratio [OR], 1.20; 95% confidence intervals [CI], 1.07-1.33) than the reference population. Welsh Corgis (OR, 3.68; 95% CI, 1.56-8.67) and Beagles (OR, 4.33; 95% CI, 1.58-11.90) were significantly predisposed to HCC. Twenty-seven of 44 dogs with HCC had at least one concurrent disorder. The most common concurrent disorder was hyperadrenocorticism (n = 10), and the adjusted odds of hyperadrenocorticism in dogs with HCC were 4.13 higher than those of the reference population (95% CI, 1.95-8.76). Propensity score matching analysis revealed that thrombocytosis (n = 30/43), increased alanine aminotransferase (n = 41/44), increased alkaline phosphatase (n = 42/44), and hypercalcemia (n = 13/32) were significantly associated with HCC diagnosis. The results of this study suggest that Welsh Corgis and Beagles are breeds with a predisposition for HCC and that hyperadrenocorticism might be a potential risk factor.

Mismatched effects of receptor interacting protein kinase-3 on hepatic steatosis and inflammation in non-alcoholic fatty liver disease

AIM

To validate the effects of receptor interacting protein kinase-3 (RIP3) deletion in non-alcoholic fatty liver disease (NAFLD) and to clarify the mechanism of action.

METHODS

Wild-type (WT) and RIP3 knockout (KO) mice were fed normal chow and high fat (HF) diets for 12 wk. The body weight was assessed once weekly. After 12 wk, the liver and serum samples were extracted. The liver tissue expression levels of RIP3, microsomal triglyceride transfer protein, protein disulfide isomerase, apolipoprotein-B, X-box binding protein-1, sterol regulatory element-binding protein-1c, fatty acid synthase, cluster of differentiation-36, diglyceride acyltransferase, peroxisome proliferator-activated receptor alpha, tumor necrosis factor-alpha (TNF-α), and interleukin-6 were assessed. Oleic acid treated primary hepatocytes from WT and RIP3KO mice were stained with Nile red. The expression of inflammatory cytokines, including chemokine (C-X-C motif) ligand (CXCL) 1, CXCL2, and TNF-α, in monocytes was evaluated.

RESULTS

RIP3KO HF diet fed mice showed a significant gain in body weight, and liver weight, liver to body weight ratio, and liver triglycerides were increased in HF diet fed RIP3KO mice compared to HF diet fed WT mice. RIP3KO primary hepatocytes also had increased intracellular fat droplets compared to WT primary hepatocytes after oleic acid treatment. RIP3 overexpression decreased hepatic fat content. Quantitative real-time polymerase chain reaction analysis showed that the expression of very-low-density lipoproteins secretion markers (microsomal triglyceride transfer protein, protein disulfide isomerase, and apolipoprotein-B) was significantly suppressed in RIP3KO mice. The overall NAFLD Activity Score was the same between WT and RIP3KO mice; however, RIP3KO mice had increased fatty change and decreased lobular inflammation compared to WT mice. Inflammatory signals (CXCL1/2, TNF-α, and interleukin-6) increased after lipopolysaccharide and pan-caspase inhibitor (necroptotic condition) treatment in monocytes. Neutrophil chemokines (CXCL1, and CXCL2) were decreased, and TNF-α was increased after RIP3 inhibitor treatment in monocytes.

CONCLUSION

RIP3 deletion exacerbates steatosis, and partially inhibits inflammation in the HF diet induced NAFLD model.