Flaxseed Powder Attenuates Non-Alcoholic Steatohepatitis via Modulation of Gut Microbiota and Bile Acid Metabolism through Gut-Liver Axis

Lactate transporter MCT4 regulates the hub genes for lipid metabolism and inflammation to attenuate intracellular lipid accumulation in non-alcoholic fatty liver disease

Non-alcoholic fatty liver disease (NAFLD) patients have multiple metabolic disturbances, with markedly elevated levels of lactate. Lactate accumulations play pleiotropic roles in disease progression through metabolic rearrangements and epigenetic modifications. Monocarboxylate transporter 4 (MCT4) is highly expressed in hepatocytes and responsible for transporting intracellular lactate out of the cell. To explore whether elevated MCT4 levels played any role in NAFLD development, we overexpressed and silenced MCT4 in hepatocytes and performed a comprehensive in vitro and in vivo analysis. Our results revealed that MCT4 overexpression down-regulated the genes for lipid synthesis while up-regulating the genes involved in lipid catabolism. Conversely, silencing MCT4 expression or inhibiting MCT4 expression led to the accumulation of intracellular lipid and glucose metabolites, resulting in hepatic steatosis. In a mouse model of NAFLD, we found that exogenous MCT4 overexpression significantly reduced lipid metabolism and alleviated hepatocellular steatosis. Mechanistically, MCT4 alleviated hepatic steatosis by regulating a group of hub genes such as Arg2, Olr1, Cd74, Mmp8, Irf7, Spp1, and Apoe, which in turn impacted multiple pathways involved in lipid metabolism and inflammatory response, such as PPAR, HIF-1, TNF, IL-17, PI3K-AKT, Wnt, and JAK-STAT. Collectively, our results strongly suggest that MCT4 may play an important role in regulating lipid metabolism and inflammation and thus serve as a potential therapeutic target for NAFLD.

TGR5 Activation by Dietary Bioactives and Related Improvement in Mitochondrial Function for Alleviating Diabetes and Associated Complications

Takeda G protein-coupled receptor 5 (TGR5), also known as G protein-coupled bile acid receptor 1 (GPBAR1), is a cell surface receptor involved in key physiological processes, including glucose homeostasis and energy metabolism. Recent research has focused on the role of TGR5 activation in preventing or treating diabetes while also highlighting its potential impact on the progression of diabetic complications. Functional foods and edible plants have emerged as valuable sources of natural compounds that can activate TGR5, offering potential therapeutic benefits for diabetes management. Despite growing interest, studies on the activation of TGR5 by dietary bioactive compounds remain scattered. This Review aims to provide a comprehensive analysis of how dietary bioactives act as potential agents for TGR5 activation in managing diabetes and its complications. It explores the mechanisms of TGR5 activation through both direct agonistic effects and indirect pathways via modulation of the gut microbiota and bile acid metabolism.

Ursodeoxycholic Acid Exhibits Greater Inhibitory Effects on Cancerous HCT116 Colon Cells than on Noncancerous NCM460 Colon Cells

Background/Objectives: Ursodeoxycholic acid (UDCA), a hydrophilic bile acid, exhibits anti-inflammatory effects and attenuates the process of colon carcinogenesis. Certain healthy diets increase colonic UDCA concentrations, but its anticancer mechanistic actions remain largely unknown. We hypothesize that UDCA preferentially inhibits cancerous colon cell proliferation with a minimal effect on noncancerous colon cells. Methods: With human noncancerous NCM460 colon cell and cancerous HCT116 colon cell culture models, we performed biochemical, western blotting, PCR array, cell cycle, apoptosis, and immunofluorescent assays to determine the effects of UDCA treatment on colon cell proliferation and the underlying molecular mechanisms. Results: The inhibitory potential of UDCA against cell proliferation (via cell cycle arrest and apoptosis) was 90% greater in cancerous HCT116 cells than noncancerous NCM460 cells when treated with UDCA (0 to 0.4 mM) for 48 h. In UDCA-treated HCT116 cells, we identified 18 genes with ≥80% change (compared to untreated cells) in mRNA levels out of 93 apoptotic genes which were involved in caspase, death receptor, and NFκB pathways. At the molecular level, 0.4 mM UDCA reduced the protein level of the proto-oncogenic c-Myc gene but increased the putative tumor suppressor p21 gene (≥100%) via the ERK1/2/c-Myc/p21 pathway, which regulates cell cycle and apoptosis. These data are consistent with lower c-Myc but higher p21 expression in normal colon tissues compared to cancerous colon tissues. Conclusions: Collectively, UDCA inhibits cancerous HCT116 colon cells to a higher degree than in noncancerous NCM460 colon cells through cell cycle and apoptosis involving ERK1/2/c-Myc/p21 signaling.

Flaxseed powder supplementation in non-alcoholic fatty liver disease: a randomized controlled clinical trial

Background: Non-alcoholic fatty liver disease (NAFLD) has become a growing public health problem worldwide, and dietary interventions have important potential in the prevention and treatment of NAFLD. Moreover, previous animal studies have shown that flaxseed has a good improvement effect in animal NAFLD models. Objectives: Assess whether flaxseed powder could improve the liver lipid content in patients with NAFLD. Methods: In this 12-week randomized controlled clinical trial, 50 patients were randomly assigned to the flaxseed group (n = 25) and the control group (n = 25). The flaxseed group received 30 g d-1 flaxseed powder orally before lunch or dinner along with health education, while the control group received only health education. The primary outcome was the intrahepatic lipid content assessed by the proton density fat fraction estimated by magnetic resonance imaging, and secondary outcomes were body composition measurements, liver function, and glucolipid metabolism. Results: Patients in the flaxseed group showed significantly lower liver fat content, body fat percentage, obesity index, visceral fat area, serum total bilirubin (TBIL), direct bilirubin (DBIL), indirect bilirubin (IBIL), aspartate aminotransferase (AST), total cholesterol (TC), and triglyceride (TG) levels after a 12-week intervention compared to pre-intervention levels, while serum apolipoprotein A1 (Apo A1) and high-density lipoprotein cholesterol (HDL-C) levels were significantly increased, with all differences being statistically significant (P < 0.05). Analysis of the gut microbiota showed that, at the phylum level, flaxseed intervention significantly increased the abundance of Bacteroides and Actinobacteria, while decreasing the ratio of Firmicutes to Bacteroidetes. At the genus level, the relative abundance of Clostridium_sensu_stricto_1, Parasutterella, Lachnospiraceae_NK4A136_group, Eubacterium_xylanophilum_group, and Bifidobacterium in the gut microbiota of the flaxseed group was significantly higher than that of the control group (P < 0.05), whereas the relative abundance of Coriobacteriaceae_UCG-002 was significantly lower than that of the control group (P < 0.05). Conclusions: Flaxseed powder intervention for 12 weeks had the effect of improving liver lipid deposition, liver function, body composition indicators, and lipid metabolism in patients with NAFLD. It also regulated the gut microbiota in NAFLD patients, increasing the abundance of beneficial bacteria while reducing harmful bacteria. This suggested that flaxseed is one of the natural and effective foods for improving NAFLD.

Bile acid and nonalcoholic steatohepatitis: Molecular insights and therapeutic targets

BACKGROUND

Nonalcoholic steatohepatitis (NASH) has been the second most common cause of liver transplantation in the United States. To date, NASH pathogenesis has not been fully elucidated but is multifactorial, involving insulin resistance, obesity, metabolic disorders, diet, dysbiosis, and gene polymorphism. An effective and approved therapy for NASH has also not been established. Bile acid is long known to have physiological detergent function in emulsifying and absorbing lipids and lipid-soluble molecules within the intestinal lumen. With more and more in-depth understandings of bile acid, it has been deemed to be a pivotal signaling molecule, which is capable of regulating lipid and glucose metabolism, liver inflammation, and fibrosis. In recent years, a plethora of studies have delineated that disrupted bile acid homeostasis is intimately correlated with NASH disease severity.

AIMS

The review aims to clarify the role of bile acid in hepatic lipid and glucose metabolism, liver inflammation, as well as liver fibrosis, and discusses the safety and efficacy of some pharmacological agents targeting bile acid and its associated pathways for NASH.

KEY SCIENTIFIC CONCEPTS OF REVIEW

Bile acid has a salutary effect on hepatic metabolic disorders, which can ameliorate liver fat accumulation and insulin resistance mainly through activating Takeda G-protein coupled receptor 5 and farnesoid X receptor. Moreover, bile acid also exerts anti-inflammation and anti-fibrosis properties. Furthermore, bile acid has great potential in nonalcoholic liver disease stratification and treatment of NASH.

Berberine Protects against High-Energy and Low-Protein Diet-Induced Hepatic Steatosis: Modulation of Gut Microbiota and Bile Acid Metabolism in Laying Hens

Berberine (BBR) is a natural alkaloid with multiple biotical effects that has potential as a treatment for fatty liver hemorrhagic syndrome (FLHS). However, the mechanism underlying the protective effect of BBR against FLHS remains unclear. The present study aimed to investigate the effect of BBR on FLHS induced by a high-energy, low-protein (HELP) diet and explore the involvement of the gut microbiota and bile acid metabolism in the protective effects. A total of 90 healthy 140-day-old Hy-line laying hens were randomly divided into three groups, including a control group (fed a basic diet), a HELP group (fed a HELP diet), and a HELP+BBR group (high-energy, high-protein diet supplemented with BBR instead of maize). Our results show that BBR supplementation alleviated liver injury and hepatic steatosis in laying hens. Moreover, BBR supplementation could significantly regulate the gut's microbial composition, increasing the abundance of Actinobacteria and Romboutsia. In addition, the BBR supplement altered the profile of bile acid. Furthermore, the gut microbiota participates in bile acid metabolism, especially taurochenodeoxycholic acid and α-muricholic acid. BBR supplementation could regulate the expression of genes and proteins related to glucose metabolism, lipid synthesis (FAS, SREBP-1c), and bile acid synthesis (FXR, CYP27a1). Collectively, our findings demonstrate that BBR might be a potential feed additive for preventing FLHS by regulating the gut microbiota and bile acid metabolism.

Human Placental Mesenchymal Stem Cells Relieve Primary Sclerosing Cholangitis via Upregulation of TGR5 in Mdr2-/- Mice and Human Intrahepatic Cholangiocyte Organoid Models

Primary sclerosing cholangitis (PSC) is a biliary disease accompanied by chronic inflammation of the liver and biliary stricture. Mesenchymal stem cells (MSCs) are used to treat liver diseases because of their immune regulation and regeneration-promoting functions. This study was performed to explore the therapeutic potential of human placental MSCs (hP-MSCs) in PSC through the Takeda G protein-coupled receptor 5 (TGR5) receptor pathway. Liver tissues were collected from patients with PSC and healthy donors (n = 4) for RNA sequencing and intrahepatic cholangiocyte organoid construction. hP-MSCs were injected via the tail vein into Mdr2-/-, bile duct ligation (BDL), and 3,5-diethoxycarbonyl-1,4-dihydrocollidine (DDC) mouse models or co-cultured with organoids to confirm their therapeutic effect on biliary cholangitis. Changes in bile acid metabolic profile were analyzed by liquid chromatography/tandem mass spectrometry (LC-MS/MS). Compared with healthy controls, liver tissues and intrahepatic cholangiocyte organoids from PSC patients were characterized by inflammation and cholestasis, and marked downregulation of bile acid receptor TGR5 expression. hP-MSC treatment apparently reduced the inflammation, cholestasis, and fibrosis in Mdr2-/-, BDL, and DDC model mice. By activating the phosphatidylinositol 3 kinase/extracellular signal-regulated protein kinase pathway, hP-MSC treatment promoted the proliferation of cholangiocytes, and affected the transcription of downstream nuclear factor κB through regulation of the binding of TGR5 and Pellino3, thereby affecting the cholangiocyte inflammatory phenotype.

Research Progress of Takeda G Protein-Coupled Receptor 5 in Metabolic Syndrome

Bile acids are acknowledged as signaling molecules involved in metabolic syndrome. The Takeda G protein-coupled receptor 5 (TGR5) functions as a significant bile acid receptor. The accumulated evidence suggests that TGR5 involves lipid homeostasis, glucose metabolism, and inflammation regulation. In line with this, recent preclinical studies also demonstrate that TGR5 plays a significant role in the generation and progression of metabolic syndrome, encompassing type 2 diabetes mellitus, obesity, atherosclerosis, and non-alcoholic fatty liver disease (NAFLD). In this review, we discuss the role of TGR5 in metabolic syndrome, illustrating the underlying mechanisms and therapeutic targets.

Multi-omics reveals that green pea (Pisum sativum L.) hull supplementation ameliorates non-alcoholic fatty liver disease via the SHMT2/glycine/mTOR/PPAR-γ signaling pathway

Diets rich in various active ingredients may be an effective intervention strategy for non-alcoholic fatty liver disease (NAFLD). The green pea hull (GPH) is a processing by-product of green peas rich in dietary fiber and polyphenols. Here, a mouse model of NAFLD induced by DSS + high-fat diet (HFD) was established to explore the intervention effect of the GPH. The results showed that dietary supplements with the GPH can inhibit obesity and reduce lipid accumulation in the mouse liver to prevent liver fibrosis. GPH intervention can improve liver antioxidant capacity, reduce blood lipid deposition and maintain glucose homeostasis. DSS-induced disruption of the intestinal barrier aggravates NAFLD, which may be caused by the influx of large amounts of LPS. A multi-omics approach combining metabolomics and transcriptomic analysis indicated that glycine was the key target and its content was decreased in the liver after GPH intervention, and that dietary supplements with the GPH can relieve NAFLD via the SHMT2/glycine/mTOR/PPAR-γ signaling pathway, which was further supported by liver-associated protein expression. In conclusion, our study demonstrated that dietary GPH can significantly ameliorate NAFLD, and the future development of related food products can enhance the economic value of the GPH.

Physiological and Pathological Considerations for the Use of Flaxseed as a Therapeutic Dietary Strategy

The inclusion of flaxseed in the diet may have a great number of potential benefits for the well-being of both healthy individuals and those challenged by disease conditions as well. With an increase in the number and quality of studies focused on the physiological and pathophysiological effects of dietary flaxseed, our knowledge concerning the rationale for the inclusion of flaxseed in our diet has become more convincing and stronger. The purpose of this review is threefold. First, the review will comprehensively document the evidence supporting the value of dietary flaxseed to improve bodily health in both normal and disease conditions. Second, this review will identify the mechanisms of action responsible for these effects. Finally, this article will review practical aspects relevant to the inclusion of flaxseed in the diet. Briefly, supplementing the diet with flaxseed has beneficial effects on the treatment and/or prevention of different kinds of cardiovascular disease (hypertension, ischemic heart disease, myocardial infarcts, atherosclerosis), non-alcoholic fatty liver disease, breast cancer, bone strength, menopause, diabetes, and wound healing. Although some controversy exists on the component within flaxseed that provides these beneficial actions, it is likely that the rich content of the omega-3 fatty acid, alpha linolenic acid, is primarily responsible for the majority of these biological effects. It is concluded that the constantly expanding evidence in support of the inclusion of flaxseed in our daily diet to provide significant health benefits strongly encourages the initiation of additional work on dietary flaxseed in order to both confirm past findings as well as to further advance our knowledge regarding the important biological actions of dietary flaxseed.

Effect of flaxseed supplementation on blood pressure: a systematic review, and dose-response meta-analysis of randomized clinical trials

Many clinical trials have revealed that flaxseed supplementation might exert a potent antihypertensive influence, but the findings are inconsistent. In this regard, a meta-analysis was carried out to provide a more accurate estimate of the impact of flaxseed supplementation on blood pressure. We searched international databases including PubMed, Cochrane Library, Web of Science, Scopus, Embase, and Google Scholar till July 2022. A random-effects model was used to calculate weighted mean differences (WMDs). Non-linear dose-response analysis and meta-regression were performed. Meta-analysis of 33 trials (comprising 43 treatment arms) with 2427 participants revealed significant reductions in both systolic (WMD: -3.19 mmHg; 95% CI: -4.15 to -2.24, p < 0.001; I² = 92.5%, p < 0.001) and diastolic blood pressure (WMD = -2.61 mmHg; 95% CI: -3.27, -1.94, p < 0.001; I² = 94.1%, p < 0.001) following flaxseed supplementation. Greater effects on SBP and DBP were found in trials with an intervention duration of >20 weeks, ≥30 g day^-1 of flaxseed, subjects with BMI 25-30 kg m^-2, and in patients with hypertension. Supplementation with various flaxseed products significantly reduced SBP and DBP levels, confirming the hypothesis that flaxseed could be used as an effective supplement for blood pressure management, alongside routine medications.

The role of bile acid metabolism in the occurrence and development of NAFLD

Non-alcoholic fatty liver disease (NAFLD) has become one of the important causes of cirrhosis and liver cancer, resulting in a huge medical burden worldwide. Currently, effective non-invasive diagnostic indicators and drugs for NAFLD are still lacking. With the development of metabolomics technology, the changes in metabolites during the development of NAFLD have been gradually revealed. Bile acid (BA) is the main endpoint of cholesterol metabolism in the body. In addition, it also acts as a signaling factor to regulate metabolism and inflammation in the body through the farnesyl X receptor and G protein-coupled BA receptor. Studies have shown that BA metabolism is associated with the development of NAFLD, but a large number of animal and clinical studies are still needed. BA homeostasis is maintained through multiple negative feedback loops and the enterohepatic circulation of BA. Recently, treatment of NAFLD by interfering with BA synthesis and metabolism has become a new research direction. Here, we review the changes in BA metabolism and its regulatory mechanisms during the development of NAFLD and describe the potential of studies exploring novel non-invasive diagnostic indicators and therapeutic targets for NAFLD based on BA metabolism.

Ferulic Acid and P-Coumaric Acid Synergistically Attenuate Non-Alcoholic Fatty Liver Disease through HDAC1/PPARG-Mediated Free Fatty Acid Uptake

Non-alcoholic fatty liver disease (NAFLD) is the most common liver disease and has become a growing public health concern worldwide. Polyphenols may improve high-fat diet (HFD)-related NAFLD. Our previous study found that ferulic acid (FA) and p-coumaric acid (p-CA) were the polyphenols with the highest content in foxtail millet. In this study, we investigated the mechanism underlying the impact of ferulic acid and p-coumaric acid (FA/p-CA) on non-alcoholic fatty liver (NAFLD). The association of FA and p-CA with fatty liver was first analyzed by network pharmacology. Synergistic ameliorating of NAFLD by FA and p-CA was verified in oleic acid (OA) and palmitic acid (PA) (FFA)-treated hepatocytes. Meanwhile, FA/p-CA suppressed final body weight and TG content and improved liver dysfunction in HFD-induced NAFLD mice. Mechanistically, our data indicated that FA and p-CA bind to histone deacetylase 1 (HDAC1) to inhibit its expression. The results showed that peroxisome proliferator activated receptor gamma (PPARG), which is positively related to HDAC1, was inhibited by FA/p-CA, and further suppressed fatty acid binding protein (FABP) and fatty acid translocase (CD36). It suggests that FA/p-CA ameliorate NAFLD by inhibiting free fatty acid uptake via the HDAC1/PPARG axis, which may provide potential dietary supplements and drugs for prevention of NAFLD.

The Species of Gut Bacteria Associated with Antitumor Immunity in Cancer Therapy

Both preclinical and clinical studies have demonstrated that the modulation of gut microbiota could be a promising strategy for enhancing antitumor immune responses and reducing resistance to immunotherapy in cancer. Various mechanisms, including activation of pattern recognition receptors, gut commensals-produced metabolites and antigen mimicry, have been revealed. Different gut microbiota modulation strategies have been raised, such as fecal microbiota transplantation, probiotics, and dietary selection. However, the identification of gut bacteria species that are either favorable or unfavorable for cancer therapy remains a major challenge. Herein, we summarized the findings related to gut microbiota species observed in the modulation of antitumor immunity. We also discussed the different mechanisms underlying different gut bacteria's functions and the potential applications of these bacteria to cancer immunotherapy in the future.

Flaxseed Bioactive Compounds: Chemical Composition, Functional Properties, Food Applications and Health Benefits-Related Gut Microbes

Flaxseed (Linum usitatissimum L.) has gained worldwide recognition as a health food because of its abundance in diverse nutrients and bioactive compounds such as oil, fatty acids, proteins, peptides, fiber, lignans, carbohydrates, mucilage, and micronutrients. These constituents attribute a multitude of beneficial properties to flaxseed that makes its use possible in various applications, such as nutraceuticals, food products, cosmetics, and biomaterials. The importance of these flaxseed components has also increased in modern times because of the newer trend among consumers of greater reliance on a plant-based diet for fulfilling their nutritional requirements, which is perceived to be hypoallergenic, more environmentally friendly, sustainable, and humane. The role of flaxseed substances in the maintenance of a healthy composition of the gut microbiome, prevention, and management of multiple diseases has recently been elucidated in various studies, which have highlighted its importance further as a powerful nutritional remedy. Many articles previously reported the nutritive and health benefits of flaxseed, but no review paper has been published reporting the use of individual flaxseed components in a manner to improve the techno-functional properties of foods. This review summarizes almost all possible applications of flaxseed ingredients in food products from an extensive online literature survey; moreover, it also outlines the way forward to make this utilization even better.

Flaxseed Ethanol Extracts’ Antitumor, Antioxidant, and Anti-Inflammatory Potential

The antitumoral, antioxidant, and anti-inflammatory effects of flaxseed ethanol extract was screened. Phytochemical analysis was performed by measuring the total phenolic content and by HPLC-DAD-ESI MS. In vitro antiproliferative activity was appreciated by MMT test of four adenocarcinomas and two normal cell lines. In vitro, antioxidant activity was evaluated by DPPH, FRAP, H₂O₂, and NO scavenging tests. The in vivo growth inhibitory activity against Ehrlich ascites carcinoma (EAC) in female BALB/c mice was determined using the trypan blue test. In EAC mice serum and ascites total oxidative status, total antioxidant reactivity, oxidative stress index, malondialdehyde, total thiols, total nitrites, 3-nitrotyrosine, and NFkB were measured. The phytochemical analysis found an significant content of phenols, with lignans having the highest concentration. The extract had an significant in vitro antioxidant effect and different inhibitory effects on different cell lines. After treatment of EAC mice with flaxseeds extract, body weight, ascites volume and viable tumour cell count, serum and ascites oxidative stress, and inflammatory markers decreased significantly. The ethanol flaxseeds extract has potential antiproliferative activity against some ovary and endometrial malignant cells and EAC. This effect can be attributed to the phenols content, and its antioxidant and anti-inflammatory activity.

Revealing the Mechanism of Huazhi Rougan Granule in the Treatment of Nonalcoholic Fatty Liver Through Intestinal Flora Based on 16S rRNA, Metagenomic Sequencing and Network Pharmacology

Background: The incidence of Nonalcoholic Fatty Liver (NAFL) is increasing year by year, growing evidence suggests that the intestinal flora plays a causative role in NAFL. Huazhi Rougan Granule (HRG) is commonly used in the clinical treatment of NAFL. It is reported that it can reduce lipids and protect the liver, but no research has confirmed whether the drug's effect is related to the intestinal flora. Therefore, we investigated whether the effect of HRG is related to the regulation of intestinal flora to further explore the mechanism of HRG in the treatment of NAFL through intestinal flora. Methods: In this study, C57BL/6J mice were fed a high-fat diet for 8 weeks, and the high-fat diet plus HRG or polyene phosphatidylcholine capsules were each administered by gavage for 4 weeks. High-throughput sequencing, network pharmacology, and molecular docking were used to explore the mechanism of HRG in the treatment of NAFL through intestinal flora. Results: HRG treatment can reduce body weight gain, lipid accumulation in liver and lipogenesis and reduce serum biochemical indexes in high-fat-fed mice. Analysis of intestinal flora showed that HRG changed the composition of intestinal flora, which was characterized by a decrease in the Firmicutes/Bacteroidetes ratio. Moreover, the species distribution was significantly correlated with AKP, HDL-C, and TG. Metagenetic analysis showed that HRG altered the functional composition and functional diversity of microorganisms, which was mainly characterized by an increase in the abundance of metabolic pathways. The network pharmacology results show that the mechanism of HRG in the treatment of NAFL through intestinal flora is mainly reflected in the biological process of gene function and related to infectious diseases, immune systems, and signal transduction pathways, such as cytokine-cytokine receptor interaction, Chagas disease, IL-17 signaling pathway and other signaling pathways. Conclusion: These results strongly suggest that HRG may alleviate NAFL by preventing IFD.

Diet and Gut Microbiota Interaction-Derived Metabolites and Intrahepatic Immune Response in NAFLD Development and Treatment

Nonalcoholic fatty liver disease (NAFLD) with pathogenesis ranging from nonalcoholic fatty liver (NAFL) to the advanced form of nonalcoholic steatohepatitis (NASH) affects about 25% of the global population. NAFLD is a chronic liver disease associated with obesity, type 2 diabetes, and metabolic syndrome, which is the most increasing factor that causes hepatocellular carcinoma (HCC). Although advanced progress has been made in exploring the pathogenesis of NAFLD and penitential therapeutic targets, no therapeutic agent has been approved by Food and Drug Administration (FDA) in the United States. Gut microbiota-derived components and metabolites play pivotal roles in shaping intrahepatic immunity during the progression of NAFLD or NASH. With the advance of techniques, such as single-cell RNA sequencing (scRNA-seq), each subtype of immune cells in the liver has been studied to explore their roles in the pathogenesis of NAFLD. In addition, new molecules involved in gut microbiota-mediated effects on NAFLD are found. Based on these findings, we first summarized the interaction of diet-gut microbiota-derived metabolites and activation of intrahepatic immunity during NAFLD development and progression. Treatment options by targeting gut microbiota and important molecular signaling pathways are then discussed. Finally, undergoing clinical trials are selected to present the potential application of treatments against NAFLD or NASH.