TLR2 inhibition ameliorates the amplification effect of LPS on lipid accumulation and lipotoxicity in hepatic cells

Metabolic-Dysfunction-Associated Steatotic Liver Disease: Molecular Mechanisms, Clinical Implications, and Emerging Therapeutic Strategies

Metabolic-dysfunction-associated steatotic liver disease (MASLD), previously known as non-alcoholic fatty liver disease (NAFLD), is a highly prevalent metabolic disorder characterized by hepatic steatosis in conjunction with at least one cardiometabolic risk factor, such as obesity, type 2 diabetes, hypertension, or dyslipidemia. As global rates of obesity and metabolic syndrome continue to rise, MASLD is becoming a major public health concern, with projections indicating a substantial increase in prevalence over the coming decades. The disease spectrum ranges from simple steatosis to metabolic-dysfunction-associated steatohepatitis (MASH), fibrosis, cirrhosis, and hepatocellular carcinoma, contributing to significant morbidity and mortality worldwide. This review delves into the molecular mechanisms driving MASLD pathogenesis, including dysregulation of lipid metabolism, chronic inflammation, oxidative stress, mitochondrial dysfunction, and gut microbiota alterations. Recent advances in research have highlighted the role of genetic and epigenetic factors in disease progression, as well as novel therapeutic targets such as peroxisome proliferator-activated receptors (PPARs), fibroblast growth factors, and thyroid hormone receptor beta agonists. Given the multifaceted nature of MASLD, a multidisciplinary approach integrating early diagnosis, molecular insights, lifestyle interventions, and personalized therapies is critical. This review underscores the urgent need for continued research into innovative treatment strategies and precision medicine approaches to halt MASLD progression and improve patient outcomes.

Reducing microglial lipid load enhances β amyloid phagocytosis in an Alzheimer's disease mouse model

Macrophages accumulate lipid droplets (LDs) under stress and inflammatory conditions. Despite the presence of LD-loaded macrophages in many tissues, including the brain, their contribution to neurodegenerative disorders remains elusive. This study investigated the role of lipid metabolism in Alzheimer's disease (AD) by assessing the contribution of LD-loaded brain macrophages, including microglia and border-associated macrophages (BAMs), in an AD mouse model. Particularly, BAMs and activated CD11c+ microglia localized near β amyloid (Aβ) plaques exhibited a pronounced lipid-associated gene signature and a high LD load. Having observed that elevated intracellular LD content correlated inversely with microglial phagocytic activities, we subsequently inhibited LD formation specifically in CX3CR1+ brain macrophages using an inducible APP-KI/Fit2iΔMφ transgenic mouse model. We demonstrated that reducing LD content in microglia and CX3CR1+ BAMs remarkably improved their phagocytic ability. Furthermore, lowering microglial LDs consistently enhanced their efferocytosis capacities and notably reduced Aβ deposition in the brain parenchyma. Therefore, mitigating LD accumulation in brain macrophages provides perspectives for AD treatment.

Rifaximin prophylaxis in MASLD‑hepatocellular carcinoma: Lessons from a negative animal model

The incidence of hepatocellular carcinoma (HCC) has been rising, particularly among individuals diagnosed with metabolic dysfunction-associated steatotic liver disease. In the present study, the prophylactic effects of rifaximin (RIF) on HCC, inflammatory markers and cardiovascular risk (CVR) were investigated in an animal model. Adult Sprague-Dawley rats were randomly allocated into three groups (n=10, each): Control [standard diet/water plus gavage with vehicle (Veh)], HCC [high-fat choline deficient diet (HFCD)/diethylnitrosamine (DEN) in drinking water/Veh gavage] and RIF [HFCD/DEN/RIF (50 mg/kg/day) gavage] groups. After euthanasia at week 16, biochemical/inflammatory markers and the liver histology were assessed. The results demonstrated that the HCC and RIF animals had a significant increase in fresh liver weight, liver weight/body weight ratio, serum total cholesterol (TC), high-density lipoprotein-cholesterol, triglycerides, hepatic lipid accumulation and hepatic concentration of triglycerides and TC, relative to the controls (P<0.001, for all). Additionally, the HCC and RIF animals had higher plasminogen activator inhibitor, intercellular adhesion molecule-1, E-selectin and CVR scores than the controls (P<0.001, for all). The HCC animals had higher interleukin (IL)-1β (P=0.011), IL-10 (P<0.001), toll-like receptor-2 (P=0.012), lipopolysaccharide-binding protein (P=0.018) and metalloproteinase-2 (P=0.003) levels than the RIF animals. Furthermore, liver steatosis, inflammation and fibrosis, along with increased collagen fiber deposition occurred in the HCC and RIF groups. However, HCC occurred only in 2 RIF rats. In conclusion, although most animals did not develop HCC in the present study, RIF positively affected liver inflammation markers involved in steatohepatitis pathogenesis.

Lipidomics Analysis of Human HMC3 Microglial Cells in an In Vitro Model of Metabolic Syndrome

Metabolic endotoxemia (ME) is associated with bacterial lipopolysaccharide (LPS, endotoxin) and increased levels of saturated fatty acids (SFAs) in the bloodstream, causing systemic inflammation. ME usually accompanies obesity and a diet rich in fats, especially SFAs. Numerous studies confirm the effect of ME-related endotoxin on microglial activation. Our study aimed to assess lipid metabolism and immune response in microglia pre-stimulated with TNFα (Tumor Necrosis Factor α) and then with endotoxin and palmitic acid (PA). Using ELISA, we determined cytokines IL-1β, IL-10, IL-13 (interleukin-1β, -10, -13, and TGFβ (Transforming Growth Factor β) in the culture medium from microglial cells stimulated for 24 h with TNFα and then treated with LPS (10 ng/mL) and PA (200 µM) for 24 h. HMC3 (Human Microglial Cells clone 3) cells produced negligible amounts of IL-1β, IL-10, and IL-13 after stimulation but secreted moderate levels of TGFβ. Changes in lipid metabolism accompanied changes in TREM2 (Triggering Receptor Expressed on Myeloid Cells 2) expression. HMC3 stimulation with endotoxin increased TREM2 expression, while PA treatment decreased it. Endotoxin increased ceramide levels, while PA increased triglyceride levels. These results indicated that pre-stimulation of microglia with TNFα significantly affects its interactions with LPS and PA and modulates lipid metabolism, which may lead to microglial activation silencing and neurodegeneration.

Fanlian Huazhuo Formula alleviates high-fat diet-induced non-alcoholic fatty liver disease by modulating autophagy and lipid synthesis signaling pathway

BACKGROUND

Fanlian Huazhuo Formula (FLHZF) has the functions of invigorating spleen and resolving phlegm, clearing heat and purging turbidity. It has been identified to have therapeutic effects on type 2 diabetes mellitus (T2DM) in clinical application. Non-alcoholic fatty liver disease (NAFLD) is frequently diagnosed in patients with T2DM. However, the therapeutic potential of FLHZF on NAFLD and the underlying mechanisms need further investigation.

AIM

To elucidate the effects of FLHZF on NAFLD and explore the underlying hepatoprotective mechanisms in vivo and in vitro.

METHODS

HepG2 cells were treated with free fatty acid for 24 hours to induce lipid accumulation cell model. Subsequently, experiments were conducted with the different concentrations of freeze-dried powder of FLHZF for 24 hours. C57BL/6 mice were fed a high-fat diet for 8-week to establish a mouse model of NAFLD, and then treated with the different concentrations of FLHZF for 10 weeks.

RESULTS

FLHZF had therapeutic potential against lipid accumulation and abnormal changes in biochemical indicators in vivo and in vitro. Further experiments verified that FLHZF alleviated abnormal lipid metabolism might by reducing oxidative stress, regulating the AMPKα/SREBP-1C signaling pathway, activating autophagy, and inhibiting hepatocyte apoptosis.

CONCLUSION

FLHZF alleviates abnormal lipid metabolism in NAFLD models by regulating reactive oxygen species, autophagy, apoptosis, and lipid synthesis signaling pathways, indicating its potential for clinical application in NAFLD.

Role of pattern recognition receptors in the development of MASLD and potential therapeutic applications

Metabolic dysfunction-associated steatotic liver disease (MASLD) has become one of the most prevalent liver diseases worldwide, and its occurrence is strongly associated with obesity, insulin resistance (IR), genetics, and metabolic stress. Ranging from simple fatty liver to metabolic dysfunction-associated steatohepatitis (MASH), even to severe complications such as liver fibrosis and advanced cirrhosis or hepatocellular carcinoma, the underlying mechanisms of MASLD progression are complex and involve multiple cellular mediators and related signaling pathways. Pattern recognition receptors (PRRs) from the innate immune system, including Toll-like receptors (TLRs), C-type lectin receptors (CLRs), NOD-like receptors (NLRs), RIG-like receptors (RLRs), and DNA receptors, have been demonstrated to potentially contribute to the pathogenesis for MASLD. Their signaling pathways can induce inflammation, mediate oxidative stress, and affect the gut microbiota balance, ultimately resulting in hepatic steatosis, inflammatory injury and fibrosis. Here we review the available literature regarding the involvement of PRR-associated signals in the pathogenic and clinical features of MASLD, in vitro and in animal models of MASLD. We also discuss the emerging targets from PRRs for drug developments that involved agent therapies intended to arrest or reverse disease progression, thus enabling the refinement of therapeutic targets that can accelerate drug development.

Network pharmacological analysis on the mechanism of Linggui Zhugan decoction for nonalcoholic fatty liver disease

Nonalcoholic fatty liver disease (NAFLD), represents a chronic progressive disease that imposes a significant burden on patients and the healthcare system. Linggui Zhugan decoction (LGZGD) plays a substantial role in treating NAFLD, but its exact molecular mechanism is unknown. Using network pharmacology, this study aimed to investigate the mechanism of action of LGZGD in treating NAFLD. Active ingredients and targets were identified through the integration of data from the TCMSP, GEO, GeneCards, and OMIM databases. Cytoscape 3.9.1 software, in conjunction with the STRING platform, was employed to construct network diagrams and screen core targets. The enrichment analysis of gene ontology and the Kyoto Encyclopedia of Genes and Genomes pathways were conducted by using the R. Molecular docking of the active ingredients and core targets was performed with AutoDock Vina software. We obtained 93 and 112 active ingredients and potential targets using the bioinformatic analysis of LGZGD in treating NAFLD. The primary ingredients of LGZGD included quercetin, kaempferol, and naringenin. The core targets were identified AKT1, MYC, HSP90AA1, HIF1A, ESR1, TP53, and STAT3. Gene ontology function enrichment analysis revealed associations with responses to nutrient and oxygen levels, nuclear receptor activity, and ligand-activated transcription factor activity. Kyoto Encyclopedia of Genes and Genomes signaling pathway analysis implicated the involvement of the PI3K-Akt, IL-17, TNF, Th17 cell differentiation, HIF-1, and TLR signaling pathways. Molecular docking studies indicated strong binding affinities between active ingredients and targets. LGZGD intervenes in NAFLD through a multi-ingredient, multi-target, and multi-pathway approach. Treatment with LGZGD can improve insulin resistance, oxidative stress, inflammation, and lipid metabolism associated with NAFLD.

Hepatocyte CYR61 polarizes profibrotic macrophages to orchestrate NASH fibrosis

Obesity is increasing worldwide and leads to a multitude of metabolic diseases, including cardiovascular disease, type 2 diabetes, nonalcoholic fatty liver disease, and nonalcoholic steatohepatitis (NASH). Cysteine-rich angiogenic inducer 61 (CYR61) is associated with the progression of NASH, but it has been described to have anti- and proinflammatory properties. We sought to examine the role of liver CYR61 in NASH progression. CYR61 liver-specific knockout mice on a NASH diet showed improved glucose tolerance, decreased liver inflammation, and reduced fibrosis. CYR61 polarized infiltrating monocytes promoting a proinflammatory/profibrotic phenotype through an IRAK4/SYK/NF-κB signaling cascade. In vitro, CYR61 activated a profibrotic program, including PDGFa/PDGFb expression in macrophages, in an IRAK4/SYK/NF-κB-dependent manner. Furthermore, targeted-antibody blockade reduced CYR61-driven signaling in macrophages in vitro and in vivo, reducing fibrotic development. This study demonstrates that CYR61 is a key driver of liver inflammation and fibrosis in NASH.

Type 2 Diabetes Mellitus and Liver Disease: Across the Gut-Liver Axis from Fibrosis to Cancer

Type 2 diabetes mellitus is a widespread disease worldwide, and is one of the cornerstones of metabolic syndrome. The existence of a strong relationship between diabetes and the progression of liver fibrosis has been demonstrated by several studies, using invasive and noninvasive techniques. Patients with type 2 diabetes mellitus (T2DM) and nonalcoholic fatty liver disease (NAFLD) show faster progression of fibrosis than patients without diabetes. Many confounding factors make it difficult to determine the exact mechanisms involved. What we know so far is that both liver fibrosis and T2DM are expressions of metabolic dysfunction, and we recognize similar risk factors. Interestingly, both are promoted by metabolic endotoxemia, a low-grade inflammatory condition caused by increased endotoxin levels and linked to intestinal dysbiosis and increased intestinal permeability. There is broad evidence on the role of the gut microbiota in the progression of liver disease, through both metabolic and inflammatory mechanisms. Therefore, dysbiosis that is associated with diabetes can act as a modifier of the natural evolution of NAFLD. In addition to diet, hypoglycemic drugs play an important role in this scenario, and their benefit is also the result of effects exerted in the gut. Here, we provide an overview of the mechanisms that explain why diabetic patients show a more rapid progression of liver disease up to hepatocellular carcinoma (HCC), focusing especially on those involving the gut-liver axis.