Hyperlipidemia May Synergize with Hypomethylation in Establishing Trained Immunity and Promoting Inflammation in NASH and NAFLD

We performed a panoramic analysis on both human nonalcoholic steatohepatitis (NASH) microarray data and microarray/RNA-seq data from various mouse models of nonalcoholic fatty liver disease NASH/NAFLD with total 4249 genes examined and made the following findings: (i) human NASH and NAFLD mouse models upregulate both cytokines and chemokines; (ii) pathway analysis indicated that human NASH can be classified into metabolic and immune NASH; methionine- and choline-deficient (MCD)+high-fat diet (HFD), glycine N-methyltransferase deficient (GNMT-KO), methionine adenosyltransferase 1A deficient (MAT1A-KO), and HFCD (high-fat-cholesterol diet) can be classified into inflammatory, SAM accumulation, cholesterol/mevalonate, and LXR/RXR-fatty acid β-oxidation NAFLD, respectively; (iii) canonical and noncanonical inflammasomes play differential roles in the pathogenesis of NASH/NAFLD; (iv) trained immunity (TI) enzymes are significantly upregulated in NASH/NAFLD; HFCD upregulates TI enzymes more than cytokines, chemokines, and inflammasome regulators; (v) the MCD+HFD is a model with the upregulation of proinflammatory cytokines and canonical and noncanonical inflammasomes; however, the HFCD is a model with upregulation of TI enzymes and lipid peroxidation enzymes; and (vi) caspase-11 and caspase-1 act as upstream master regulators, which partially upregulate the expressions of cytokines, chemokines, canonical and noncanonical inflammasome pathway regulators, TI enzymes, and lipid peroxidation enzymes. Our findings provide novel insights on the synergies between hyperlipidemia and hypomethylation in establishing TI and promoting inflammation in NASH and NAFLD progression and novel targets for future therapeutic interventions for NASH and NAFLD, metabolic diseases, transplantation, and cancers.

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Adipocyte, Immune Cells, and miRNA Crosstalk: A Novel Regulator of Metabolic Dysfunction and Obesity

Cells ◽

10.3390/cells10051004 ◽

2021 ◽

Vol 10 (5) ◽

pp. 1004

Author(s):

Sonia Kiran ◽

Vijay Kumar ◽

Santosh Kumar ◽

Robert L Price ◽

Udai P. Singh

Keyword(s):

Insulin Resistance ◽

Immune Response ◽

T Cells ◽

Immune Cells ◽

Metabolic Diseases ◽

Liver Disorder ◽

Low Grade ◽

Peripheral Tissues ◽

Nonalcoholic Fatty Liver ◽

Cytokines And Chemokines

Obesity is characterized as a complex and multifactorial excess accretion of adipose tissue (AT) accompanied with alterations in the immune response that affects virtually all age and socioeconomic groups around the globe. The abnormal accumulation of AT leads to several metabolic diseases, including nonalcoholic fatty liver disorder (NAFLD), low-grade inflammation, type 2 diabetes mellitus (T2DM), cardiovascular disorders (CVDs), and cancer. AT is an endocrine organ composed of adipocytes and immune cells, including B-Cells, T-cells and macrophages. These immune cells secrete various cytokines and chemokines and crosstalk with adipokines to maintain metabolic homeostasis and low-grade chronic inflammation. A novel form of adipokines, microRNA (miRs), is expressed in many developing peripheral tissues, including ATs, T-cells, and macrophages, and modulates the immune response. miRs are essential for insulin resistance, maintaining the tumor microenvironment, and obesity-associated inflammation (OAI). The abnormal regulation of AT, T-cells, and macrophage miRs may change the function of different organs including the pancreas, heart, liver, and skeletal muscle. Since obesity and inflammation are closely associated, the dysregulated expression of miRs in inflammatory adipocytes, T-cells, and macrophages suggest the importance of miRs in OAI. Therefore, in this review article, we have elaborated the role of miRs as epigenetic regulators affecting adipocyte differentiation, immune response, AT browning, adipogenesis, lipid metabolism, insulin resistance (IR), glucose homeostasis, obesity, and metabolic disorders. Further, we will discuss a set of altered miRs as novel biomarkers for metabolic disease progression and therapeutic targets for obesity.

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Lipid droplets are both highly oxidized and Plin2-covered in hepatocytes of diet-induced obese mice

Applied Physiology Nutrition and Metabolism ◽

10.1139/apnm-2019-0966 ◽

2020 ◽

Vol 45 (12) ◽

pp. 1368-1376

Author(s):

Diego Nocetti ◽

Alejandra Espinosa ◽

Francisco Pino-De la Fuente ◽

Camila Sacristán ◽

José Luis Bucarey ◽

...

Keyword(s):

Lipid Peroxidation ◽

High Fat Diet ◽

Lipid Droplets ◽

Control Diet ◽

Isolated Hepatocytes ◽

High Fat ◽

Nonalcoholic Fatty Liver ◽

Adult Mice ◽

Obesity Status ◽

Intrahepatic Lipid

Chronic high-fat diet feeding is associated with obesity and accumulation of fat in the liver, leading to the development of insulin resistance and nonalcoholic fatty liver disease. This condition is characterized by the presence of a high number of intrahepatic lipid droplets (LDs), with changes in the perilipin pattern covering them. This work aimed to describe the distribution of perilipin (Plin) 2, an LD-associated protein involved in neutral lipid storage, and Plin5, which favors lipid oxidation in LD, and to evaluate lipid peroxidation through live-cell visualization using the lipophilic fluorescent probe C11-BODIPY581/591 in fresh hepatocytes isolated from mice fed a high-fat diet (HFD). Male C57BL/6J adult mice were divided into control and HFD groups and fed with a control diet (10% fat, 20% protein, and 70% carbohydrates) or an HFD (60% fat, 20% protein, and 20% carbohydrates) for 8 weeks. The animals fed the HFD showed a significant increase of Plin2 in LD of hepatocytes. LD from HFD-fed mice have a stronger lipid peroxidation level than control hepatocytes. These data provide evidence that obesity status is accompanied by a higher degree of lipid peroxidation in hepatocytes, both in the cytoplasm and in the fats stored inside the LD. Novelty Our study shows that lipid droplets from isolated hepatocytes in HFD-fed mice have a stronger lipid peroxidation level than control hepatocytes. C11-BODIPY581/591 is a useful tool to measure the initial level of intracellular lipid peroxidation in single isolated hepatocytes. Perilipins pattern changes with HFD feeding, showing an increase of Plin2 covering lipid droplets.

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Why Hepatic CYP2E1-Elevation by Itself Is Insufficient for Inciting NAFLD/NASH: Inferences from Two Genetic Knockout Mouse Models

Biology ◽

10.3390/biology9120419 ◽

2020 ◽

Vol 9 (12) ◽

pp. 419

Author(s):

Maria Almira Correia ◽

Doyoung Kwon

Keyword(s):

Liver Disease ◽

Mouse Models ◽

Ubiquitin Ligase ◽

Metabolic Diseases ◽

E3 Ubiquitin Ligase ◽

Metabolic Activation ◽

Chow Diet ◽

Hepatic Lipogenesis ◽

Nonalcoholic Fatty Liver ◽

Genetic Ablation

Hepatic cytochrome P450 CYP2E1 is an enzyme engaged in the metabolic biotransformation of various xenobiotics and endobiotics, resulting in both detoxification and/or metabolic activation of its substrates to more therapeutic or toxic products. Elevated hepatic CYP2E1 content is implicated in various metabolic diseases including alcoholic liver disease, nonalcoholic fatty liver disease (NAFLD)/nonalcoholic steatohepatitis (NASH), diabetes and obesity. While hepatic CYP2E1 elevation is considered essential to the pathogenesis of these liver diseases, our findings in two mouse models of E3 ubiquitin ligase genetic ablation fed a regular lab chow diet, argue that it is not sufficient for triggering NAFLD/NASH. Thus, albeit comparable hepatic CYP2E1 elevation and functional stabilization in these two models upon E3 ubiquitin ligase genetic ablation and consequent disruption of its ubiquitin-dependent proteasomal degradation, NAFLD/NASH was only observed in the mouse livers that exhibited concurrent SREBP1c-transcriptional upregulation of hepatic lipogenesis. These findings reinforce the critical complicity of an associated prolipogenic scenario induced by either an inherently upregulated hepatic lipogenesis or a high fat/high carbohydrate diet in CYP2E1-mediated NAFLD/NASH.

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A dietary ketone ester mitigates histological outcomes of NAFLD and markers of fibrosis in high-fat diet fed mice

AJP Gastrointestinal and Liver Physiology ◽

10.1152/ajpgi.00259.2020 ◽

2021 ◽

Author(s):

Mary P Moore ◽

Rory P Cunningham ◽

Rachel A. H. Davis ◽

Sarah E. Deemer ◽

Brandon M. Roberts ◽

...

Keyword(s):

High Fat Diet ◽

Inflammatory Markers ◽

Metabolic Diseases ◽

Stellate Cell ◽

High Fat ◽

Nonalcoholic Fatty Liver ◽

Hepatic Markers ◽

Nafld Activity Score ◽

Ketone Ester

Nutritional ketosis as a therapeutic tool has extended to the treatment of metabolic diseases including - obesity, type 2 diabetes and nonalcoholic fatty liver disease. The purpose of this study was to determine whether dietary administration of the ketone ester (KE), R,S-1,3-butanediol diacetoacetate (BD-AcAc2), attenuates markers of hepatic stellate cell (HSC) activation and hepatic fibrosis in the context of high fat diet (HFD)-induced obesity. Six-week-old male C57BL/6J mice were placed on a 10-week ad libitum HFD (45% FAT, 32% CHO, 23% PRO). Mice were then randomized to 1 of 3 groups (n = 10 per group) for an additional 12 weeks: 1) control (CON), continuous HFD, 2) pair-fed (PF) to KE; and 3) KE (HFD+30% energy from BD-AcAc2, KE). KE feeding significantly reduced histological steatosis, inflammation and total NAFLD activity score vs CON, beyond improvements observed for calorie restriction alone (PF). Dietary KE supplementation also reduced the protein content and gene expression of pro-fibrotic markers (α-SMA, Col1a1, PDGF-β, MMP9) vs CON (p<0.05), beyond reductions observed for PF vs CON. Furthermore, KE feeding increased hepatic markers of anti-inflammatory M2 macrophages (CD163) and also reduced pro-inflammatory markers (TRAIL and CCN1) vs CON and PF (p ≤ 0.05), in the absence of changes in markers of total hepatic macrophage content (F4/80 and CD68; p > 0.05). These data highlight that the dietary ketone ester, BD-AcAc2, ameliorates histological NAFLD and inflammation and reduces pro-fibrotic and pro-inflammatory markers. Future studies to further explore potential mechanisms are warranted.

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Gegen Qinlian Decoction Attenuates High-Fat Diet-Induced Steatohepatitis in Rats via Gut Microbiota

Evidence-based Complementary and Alternative Medicine ◽

10.1155/2018/7370891 ◽

2018 ◽

Vol 2018 ◽

pp. 1-8 ◽

Cited By ~ 7

Author(s):

Yi Guo ◽

Pang-hua Ding ◽

Li-juan Liu ◽

Lei Shi ◽

Tang-you Mao ◽

...

Keyword(s):

Gut Microbiota ◽

Group Treatment ◽

High Fat Diet ◽

Metabolic Diseases ◽

Intestinal Flora ◽

Underlying Mechanism ◽

Control Group ◽

High Fat ◽

Nonalcoholic Fatty Liver ◽

Traditional Chinese Herbal Medicine

Gut microbiota play an important role in modulating energy contribution, metabolism, and inflammation, and disruption of the microbiome population is closely associated with chronic metabolic diseases, such as nonalcoholic fatty liver disease (NAFLD). Gegen Qinlian decoction (GGQLD), a well-known traditional Chinese herbal medicine (CHM), was previously found to regulate lipid metabolism and attenuate inflammation during NAFLD pathogenesis. However, the underlying mechanism of this process, as well as how the gut microbiome is involved, remains largely unknown. In this study, we investigated the effect of varying doses of GGQLD on the total amount and distribution of gut bacteria in rats fed a high-fat diet (HFD) for 8 weeks. Our analysis indicates that Oscillibacter and Ruminococcaceae_g_unclassified are the dominant families in the HFD group. Further, HFD-dependent differences at the phylum, class, and genus levels appear to lead to dysbiosis, characterized by an increase in the Firmicutes/Bacteroidetes ratio and a dramatic increase in the Oscillibacter genus compared to the control group. Treatment with GGQLD, especially the GGQLL dose, improved these HFD-induced changes in intestinal flora, leading to increased levels of Firmicutes, Clostridia, Lactobacillus, bacilli, and Erysipelotrichales that were similar to the controls. Taken together, our data highlight the efficacy of GGQLD in treating NAFLD and support its clinical use as a treatment for NAFLD/NASH patients.

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Establishment and Comparison of Juvenile Female Mouse Models of Nonalcoholic Fatty Liver Disease and Nonalcoholic Steatohepatitis

Gastroenterology Research and Practice ◽

10.1155/2018/8929620 ◽

2018 ◽

Vol 2018 ◽

pp. 1-14 ◽

Cited By ~ 3

Author(s):

Lishan Zhou ◽

Deliang Liu ◽

Zhiwei Wang ◽

Hui Dong ◽

Xiaohu Xu ◽

...

Keyword(s):

Liver Disease ◽

Mouse Models ◽

Female Mouse ◽

Fatty Liver Disease ◽

Female Offspring ◽

Fat Intake ◽

High Fat ◽

Nonalcoholic Fatty Liver ◽

Juvenile Female ◽

Successful Establishment

Experimental research has successfully established an adult offspring animal model of nonalcoholic fatty liver disease (NAFLD), but the female offspring model of NAFLD in young age has not been well characterized yet. The aim of this study was to present a direct comparison of the maternal versus postweaning female juvenile NAFLD and nonalcoholic steatohepatitis (NASH) animal models. Four different female mouse models were established and compared using different high-fat diet feeding (HF) strategies in maternal mice and their offspring. The models were non-HF maternal mice and HF offspring with high-high fat (C/HHF), non-HF maternal mice and HF offspring with low-high fat (C/LHF), HF maternal mice and offspring both with high-high fat (HHF/HHF), and HF maternal mice and offspring both with low-high fat (LHF/LHF). A female control group (C/C) was also established. The offspring mice were raised to the age of 8 weeks and then euthanized. Blood glucose levels, lipid profiles, liver function, and triglycerides/total cholesterol contents were examined. Hepatic morphology and superoxide anion levels were evaluated. The nicotinamide-adenine dinucleotide phosphate activity and related regulatory subunits protein expression in the liver tissue were also determined. Our data demonstrated that offspring fat intake contributed to the successful establishment of NAFLD and maternal-offspring fat intake contributed to the successful establishment of NASH in juvenile female mice. Offspring high-fat exposure might be associated with the development of NAFLD and maternal high-fat exposure might be associated with the development of NASH in juvenile female offspring. Higher calories from a fat diet program (both in maternal and offspring) are more prone to inducing liver injury in offspring. In addition, the combination of the aforementioned two factors could aggravate this process. Moreover, oxidative stress was prominent in the juvenile female mouse model of NAFLD/NASH, and the mechanism might be related to the activation of liver NADPH oxidase.

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Anethole dithiolethione improves liver fatty acid metabolism in hamster fed high-fat diets

10.1101/2020.02.18.954875 ◽

2020 ◽

Author(s):

Chengcheng Zhao ◽

Nannan Yu ◽

Wenqun Li ◽

Hualin Cai ◽

Mouze Liu ◽

...

Keyword(s):

Fatty Acids ◽

Metabolic Diseases ◽

Monounsaturated Fatty Acids ◽

Lipid Lowering ◽

High Fat ◽

Nonalcoholic Fatty Liver ◽

Syrian Golden Hamsters ◽

Liver Injuries ◽

Fat Diets ◽

Excessive Accumulation

Abstract“Lipotoxicity” induced by excessive accumulation of free fatty acids (FFAs) in the liver, especially saturated FAs and their toxic metabolites, is closely related to metabolic diseases such as nonalcoholic fatty liver disease (NAFLD). Hydrogen sulfide (H2S), a novel gaseous signaling molecule, has been reported to have lipid-lowering effects, but its effect on FAs metabolism remains unclear. The purpose of this study was to investigate the effect and mechanisms of anethole dithiolethione (ADT, a sustained-release H2S donor) on hepatic FAs metabolism. ADT was administered daily for 4 weeks in male Syrian golden hamsters fed a high fat diet (HFD), and FAs profiles of liver tissues were analyzed using GC-MS. The results showed that in HFD-fed hamsters, ADT treatment significantly reduced the accumulation of saturated and monounsaturated fatty acids (C16:0, C18:0, C16:1, and C18:1n9), while increased the content of n-6 and n-3 series polyunsaturated fatty acids (C20:3n6, C20:4n6, and C22:6n3). Mechanistically, ADT obviously inhibited the overexpression of ACC1, FAS and SCD1, and up-regulated the levels of FATPs, L-FABP, CPT1α, FADS1 and FADS2. Notably, ADT evidently induced Mitofusin1 to facilitate mitochondrial fusion and optimize β-oxidation. These findings suggest that ADT plays a beneficial role by regulating the synthesis, desaturation, β-oxidation, uptake, binding/isolation, and transport of FAs. In conclusion, ADT is effective in improving liver FAs metabolic disorders and liver injuries caused by HFD.

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