Macrophages and the development and progression of non-alcoholic fatty liver disease

Macrophage inhibition in the alleviation of nonalcoholic steatohepatitis caused by bariatric surgery

The incidence of nonalcoholic steatohepatitis (NASH) is increasing worldwide, and effective treatment is urgently needed. To understand the molecular mechanisms behind the effectiveness of bariatric surgery in treating NASH, we integrated single-cell and bulk RNA sequencing data to identify the role of liver macrophage polarization in alleviating NASH and screen possible drugs for treatment. Analysis revealed that bariatric surgery alleviates NASH by inhibiting liver M1 macrophage polarization with 12 differentially expressed M1 macrophage-related genes. Additionally, 56 potentially effective drugs were predicted for NASH treatment. These findings shed light on the effectiveness of bariatric surgery in treating NASH and offer potential drug candidates for further exploration.

Knowledge landscape of macrophage research in liver fibrosis: a bibliometric review of the literature from WoSCC

Recent insights into the immune response in fibrosis have provided valuable perspectives for the treatment of liver fibrosis. Macrophages, as the most abundant immune cells in the liver, are key drivers of liver fibrosis. They are extensively involved in tissue damage, chronic inflammation, and the progression and regression of liver fibrosis. This study aims to conduct a bibliometric analysis and literature review on the mechanisms by which macrophages contribute to liver fibrosis. Specifically, we analyzed a bibliometric dataset comprising 1,312 papers from 59 countries, 1,872 institutions, and 9,784 authors. Keyword co-occurrence analysis identified key research hotspots, including the role of macrophage subtypes in obesity-related metabolic disorders, the crosstalk between macrophages and hepatic stellate cells through mechanoimmunology, emerging strategies for immune modulation targeting macrophages to promote fibrosis regression and liver regeneration, and new discoveries regarding macrophage crosstalk with other immune cells. In conclusion, this study provides a visual analysis of the current research landscape, hotspots, and trends in the field of macrophages and liver fibrosis, and discusses future directions for further exploration in this area.

Targeting regulation of lipid metabolism with polysaccharide of traditional Chinese medicine for the treatment of non-alcoholic fatty liver disease: A review

Non-alcoholic fatty liver disease (NAFLD) has become one of the most common chronic diseases in the world, and the effective treatment of NAFLD has been listed as a key problem to be solved urgently in contemporary medicine. Polysaccharides in traditional Chinese medicine (TCM) have a wide range of pharmacological activities. A large number of preclinical studies have confirmed that TCM polysaccharides can interfere with the occurrence and development of NAFLD at multiple interrelated levels, such as improving lipid metabolism and insulin resistance, regulating oxidative stress, alleviating immune inflammatory response, and regulating intestinal microbiota, thus showing great potential as a new anti-NAFLD drug. This paper summarizes the prevention and treatment effect and mechanism of TCM polysaccharides on NAFLD, which provides a basis for the application of TCM polysaccharides in plant medicine and modern medicines, and provides a reference for promoting the development and utilization of TCM polysaccharide resources and the research and development of new drugs for NAFLD.

The role of hepatic sinusoidal microenvironment in NASH: pathogenesis, animal models, and therapeutic prospects

The incidence of nonalcoholic steatohepatitis (NASH) is increasing annually, posing a significant threat to human health. NASH is typified by hepatic steatosis, inflammation, and hepatocellular injury, frequently culminating in fibrosis and cirrhosis. Yet, the precise pathogenesis of NASH remains to be fully elucidated. The hepatic sinusoid, which serves as the fundamental structural and functional unit of the liver, is intricately composed of endothelial cells, Kupffer cells, and hepatic stellate cells. Consequently, the homeostasis of the hepatic sinusoidal microenvironment may exert a pivotal influence on the progression and prognosis of NASH. However, the limitations of current NASH animal models have significantly impeded advancements in understanding the disease's pathogenesis and the development of effective therapeutic interventions. In light of these challenges, this review endeavors to delve deeper into the critical role of hepatic sinusoidal microenvironment homeostasis in the pathogenesis of NASH, critically analyze the commonly employed animal models, and comprehensively summarize the most recent and promising developments in drug research and development. It is anticipated that these efforts will collectively expedite the advancement of the field of NASH research and therapeutic innovation.

Ablation of Hepatic Asah1 Gene Disrupts Hepatic Lipid Homeostasis and Promotes Fibrotic Nonalcoholic Steatohepatitis in Mice

Nonalcoholic fatty liver disease (NAFLD) encompasses a spectrum of chronic liver conditions, ranging from simple steatosis to nonalcoholic steatohepatitis, which may progress to fibrosis/cirrhosis. Here, the GSE163211 data set was analyzed, and Asah1 (encoding acid ceramidase) was identified as a crucial lysosomal gene that positively correlated with NAFLD stages in obese patients. To evaluate the role of Asah1 in the progression of NAFLD, Asah1fl/fl/Albcre mice (hepatocyte-specific deletion of Asah1) and Asah1 floxed (Asah1fl/fl/wild-type) mice were fed with either a normal diet or a high-fat, high-cholesterol paigen diet (PD) for 20 weeks. Hepatocyte-specific Asah1 ablation markedly aggravated PD-induced hepatic steatosis, hepatitis, and apoptosis, and resulted in marked fibrotic changes. In addition, Asah1 gene ablation exacerbated PD-induced portal venous hemodynamic abnormality. In cultured hepatocytes, Asah1 gene knockdown resulted in increased ceramide and cholesterol levels but did not affect triglyceride level. Knocking down Asah1 gene also exhibited broad impacts on lipid homeostasis pathways, including lipogenesis, fatty acid uptake, fatty acid oxidation, and lipid transport. Furthermore, Asah1 knockdown resulted in increased endoplasmic reticulum stress and lipid droplet biogenesis. Finally, Asah1 gene knockdown impaired chaperone-mediated autophagy. These results suggest that Asah1 functions as an important regulator of hepatic lipid homeostasis, and its deficiency exacerbates hepatocyte lipotoxicity and injury, and promotes the development of fibrotic nonalcoholic steatohepatitis.

Role of the FOXM1/CMA/ER stress axis in regulating the progression of nonalcoholic steatohepatitis

BACKGROUND/AIMS

The molecular mechanisms driving nonalcoholic steatohepatitis (NASH) progression are poorly understood. This research examines the involvement of chaperone-mediated autophagy (CMA) in NASH progression.

METHODS

Hepatic CMA activity was analysed in NASH mice and patients. Lysosome-associated membrane protein 2A (LAMP2A) was knocked down or overexpressed to assess the effects of hepatocyte-specific CMA on NASH progression. Mice received a high-fat diet or a methionine and choline-deficient diet to induce NASH. Palmitic acid was employed to mimic lipotoxicity-induced hepatocyte damage in vitro. The promoter activity of FOXM1 was evaluated via ChIP and dual-luciferase reporter assays.

RESULTS

Hepatic CMA activity was substantially low in NASH mice and patients. LAMP2A knockdown resulted in hepatocyte-specific CMA deficiency, which promoted fibrosis and hepatic inflammation in NASH mice. Both in vitro and in vivo, CMA deficiency also exacerbated hepatocyte damage and endoplasmic reticulum (ER) stress. Mechanistically, CMA deficiency in hepatocytes increased cholesterol accumulation by blocking the degradation of 3-hydroxy-3-methylglutaryl coenzyme A (HMGCR), a key cholesterol synthesis-related enzyme, and the accumulated cholesterol subsequently induced ER stress and hepatocyte damage. The restoration of hepatocyte-specific CMA activity effectively ameliorated diet-induced NASH and ER stress in vivo and in vitro. FOXM1 directly bound to LAMP2A promoter and negatively regulated its transcription. The upregulation of FOXM1 expression impaired CMA and enhanced ER stress, which in turn increased FOXM1 expression, resulting in a vicious cycle and promoting NASH development.

CONCLUSIONS

This study highlights the significance of the FOXM1/CMA/ER stress axis in NASH progression and proposes novel therapeutic targets for NASH.

KEY POINTS

Chaperone-mediated autophagy (CMA) deficiency in hepatocytes promotes hepatic inflammation and fibrosis in mice with nonalcoholic steatohepatitis (NASH) by inducing cholesterol accumulation and endoplasmic reticulum (ER) stress. Upregulated FOXM1 impairs CMA by suppressing the transcription of lysosome-associated membrane protein 2A (LAMP2A), a rate-limiting component of CMA. ER stress increases FOXM1 expression and cholesterol accumulation. FOXM1/CMA/ER stress axis forms a vicious circle and promotes the development of NASH.

Identification of conserved and tissue-restricted transcriptional profiles for lipid associated macrophages (LAMs)

Macrophages are essential immune cells present in all tissues, and are vital for maintaining tissue homeostasis, immune surveillance, and immune responses. Considerable efforts have identified shared and tissue-specific gene programs for macrophages across organs during homeostasis. This information has dramatically enhanced our understanding of tissue-restricted macrophage programming and function. However, few studies have addressed the overlapping and tissue-specific responses of macrophage subsets following inflammatory responses. One subset of macrophages that has been observed across several studies, lipid-associated macrophages (LAMs), have gained interest due to their unique role in lipid metabolism and potential as a therapeutic target. LAMs have been associated with regulating disease outcomes in metabolically related disorders including atherosclerosis, obesity, and nonalcoholic fatty liver disease (NAFLD). In this study, we utilized single-cell RNA sequencing (scRNAseq) data to profile LAMs across multiple tissues and sterile inflammatory conditions in mice and humans. Integration of data from various disease models revealed that LAMs share a set of conserved transcriptional profiles, including Trem2 and Lpl, but also identified key sets of tissue-specific LAM gene programs. Importantly, the shared LAM markers were highly conserved with human LAM populations that also emerge in chronic inflammatory settings. Overall, this analysis provides a detailed transcriptional landscape of tissue-restricted and shared LAM gene programs and offers insights into their roles in metabolic and chronic inflammatory diseases. These data may help instruct appropriate targets for broad or tissue-restricted therapeutic interventions to modulate LAM populations in disease.

RANK-RANKL-OPG Axis in MASLD: Current Evidence Linking Bone and Liver Diseases and Future Perspectives

Metabolic dysfunction-associated steatotic liver disease (MASLD)-and its worse form, metabolic-associated steatohepatitis (MASH), characterised by inflammation and liver damage-corresponds to the liver's involvement in metabolic syndrome, which constitutes an economic burden for healthcare systems. However, the biomolecular pathways that contribute to steatotic liver disease are not completely clear. Abnormalities of bone metabolism are frequent in people affected by metabolic liver disease, with reduced bone density and an increased risk of fracture. Receptor activator of NF-κB (RANK), receptor activator of NF-κB ligand (RANKL), and osteoprotegerin(OPG) are critical regulators of bone metabolism, performing pleiotropic effects, and may have potential involvement in metabolic disorders like MASLD, resulting in a topic of great interest and intrigue. This narrative review aims to investigate this potential role and its implications in MASLD development and progression and in hepatocellular carcinoma, which represents its worst complication.

Reactive oxygen species regulation by NCF1 governs ferroptosis susceptibility of Kupffer cells to MASH

Impaired self-renewal of Kupffer cells (KCs) leads to inflammation in metabolic dysfunction-associated steatohepatitis (MASH). Here, we identify neutrophil cytosolic factor 1 (NCF1) as a critical regulator of iron homeostasis in KCs. NCF1 is upregulated in liver macrophages and dendritic cells in humans with metabolic dysfunction-associated steatotic liver disease and in MASH mice. Macrophage NCF1, but not dendritic cell NCF1, triggers KC iron overload, ferroptosis, and monocyte-derived macrophage infiltration, thus aggravating MASH progression. Mechanistically, elevated oxidized phospholipids induced by macrophage NCF1 promote Toll-like receptor (TLR4)-dependent hepatocyte hepcidin production, leading to increased KC iron deposition and subsequent KC ferroptosis. Importantly, the human low-functional polymorphic variant NCF190H alleviates KC ferroptosis and MASH in mice. In conclusion, macrophage NCF1 impairs iron homeostasis in KCs by oxidizing phospholipids, triggering hepatocyte hepcidin release and KC ferroptosis in MASH, highlighting NCF1 as a therapeutic target for improving KC fate and limiting MASH progression.

Extracellular Vesicles and Their Correlation with Inflammatory Factors in an Experimental Model of Steatotic Liver Disease Associated with Metabolic Dysfunction

Background/Aims: Extracellular vesicles (EVs) are promising as a biomarker of metabolic dysfunction associated steatotic liver disease (MASLD). The objective is to study EVs and their involvement in MASLD concerning the disease's pathogenesis and progression characteristics. Methods: Male adult Sprague Dawley rats were randomly assigned into two experimental models of MASLD: MASLD-16 and MASLD-28, animals received a choline-deficient high-fat diet (CHFD) and Control-16 and Control-28, animals received a standard diet (SD) for 16 and 28 weeks, respectively. Biological samples from these animal models were used, as well as previously registered variables. EVs from hepatic tissue were characterized using confocal microscopy. EVs were isolated through differential ultracentrifugation from serum and characterized using NanoSight. The data from the EVs were correlated with biochemical, molecular, and histopathological parameters. Results: Liver EVs were identified through the flotillin-1 protein. EVs were isolated from the serum of all groups. There was a decrease of EVs concentration in MASLD-28 in comparison with Control-28 (P < 0.001) and a significant increase in EVs concentration in Control-28 compared with Control-16 (P < 0.001). There was a strong correlation between serum EVs concentration with hepatic gene expression of interleukin (Il)6 (r2 = 0.685, P < 0.05), Il1b (r2 = 0.697, P < 0.05) and tumor necrosis factor-alpha (Tnfa; r2 = 0.636, P < 0.05) in MASLD-16. Moreover, there was a strong correlation between serum EVs size and Il10 in MASLD-28 (r2 = 0.762, P < 0.05). Conclusion: The concentration and size of EVs correlated with inflammatory markers, suggesting their involvement in the systemic circulation, cellular communication, and development and progression of MASLD, demonstrating that EVs have the potential to serve as noninvasive biomarkers for MASLD diagnosis and prognosis.

Recent Advances in Liver Tissue Engineering as an Alternative and Complementary Approach for Liver Transplantation

Acute and chronic liver diseases cause significant morbidity and mortality worldwide, affecting millions of people. Liver transplantation is the primary intervention method, replacing a non-functional liver with a functional one. However, the field of liver transplantation faces challenges such as donor shortage, postoperative complications, immune rejection, and ethical problems. Consequently, there is an urgent need for alternative therapies that can complement traditional transplantation or serve as an alternative method. In this review, we explore the potential of liver tissue engineering as a supplementary approach to liver transplantation, offering benefits to patients with severe liver dysfunctions.