NAFLD: The evolving landscape

Early-life antibiotic exposure aggravate the metabolic dysfunction-associated steatotic liver disease associated hepatocellular carcinoma

BACKGROUND

Metabolic dysfunction-associated steatotic liver disease (MASLD) asscociated hepatocellular carcinoma (HCC) is becoming a growing concern in global healthcare. The early-life gut microbiota plays a crucial role in maintaining healthy. However, the impact of early-life gut microbiota dysbiosis on the advancement of MASLD-HCC remains inadequately understood.

METHODS

In the present study, we investigated the role of early-life gut microbiota in the development of MASLD-HCC in streptozotocin and high-fat diet (STZ-HFD) induced mouse model. We recorded the body weight and lifespan, and dynamically monitored the level of alanine aminotransferase (ALT), aspartate aminotransferase (AST), triglyceride (TG), total cholesterol (T-CHO) and blood glucose in the serum monthly. In addition, we examined various immune cells present in the liver, such as T cells, B cells, NK cells, NKT cells, αβT cells, γδT cells, macrophage and MDSC cells by flow cytometry and conducted liquid chromatography mass spectrometry (LC-MS) based analysis on liver tissue from control and early-life antibiotic exposure mice (early-Abx) MASLD-HCC mice.

RESULTS

We found that early-Abx mice suffered from more severe tumor burden and further confirmed that hepatocytes and immune cells were all disturbed. Importantly, early-life antibiotic exposure alters the liver metabolic profiling especially glycerophospholipids and lipid accumulation. Furthermore, mice exposed to antibiotics in early-life showed disturbances in glucose metabolism and developed insulin resistance.

CONCLUSIONS

Collectively, our findings revealed that early-life antibiotic exposure accelerated the progression of MASLD-HCC by impairing the hepatocytes, immune homeostasis and metabolites persistently, highlighting the importance of the early-life microbiota in the development of MASLD-HCC.

Natural compounds proposed for the management of non-alcoholic fatty liver disease

Although non-alcoholic fatty liver disease (NAFLD) presents as an intricate condition characterized by a growing prevalence, the often-recommended lifestyle interventions mostly lack high-level evidence of efficacy and there are currently no effective drugs proposed for this indication. The present review delves into NAFLD pathology, its diverse underlying physiopathological mechanisms and the available in vitro, in vivo, and clinical evidence regarding the use of natural compounds for its management, through three pivotal targets (oxidative stress, cellular inflammation, and insulin resistance). The promising perspectives that natural compounds offer for NAFLD management underscore the need for additional clinical and lifestyle intervention trials. Encouraging further research will contribute to establishing more robust evidence and practical recommendations tailored to patients with varying NAFLD grades.

Faeces-derived extracellular vesicles participate in the onset of barrier dysfunction leading to liver diseases

The role of extracellular vesicles (EVs) from faeces (fEVs) and small circulating EVs (cEVs) in liver diseases such as non-alcoholic fatty diseases (NAFLD) and non-alcoholic steatohepatitis (NASH) has not been demonstrated. fEVs and cEVs of healthy donors, NAFLD and NASH patients were isolated and characterized. The effects of EVs were evaluated in intestinal, endothelial, Kupffer and stellate cells. Non-muscular myosin light chain kinase (nmMLCK) deficient mice were used in vivo. Bacterial origins of fEVs were analysed by 16s rDNA gene sequencing. fEVs and small cEVs were composed of prokaryotic and eukaryotic origins. Only NASH-fEVs exerted deleterious effects. NASH-fEVs increased intestinal permeability and reduced expression of tight junction proteins that were prevented by nmMLCK inhibition, increased endothelial cell permeability and inflammatory cytokines and chemokines requiring TLR4/lipopolysaccharide pathway. NASH-fEVs and NASH-cEVs activated profibrotic and proinflammatory proteins of hepatic stellate cells. Treatment with NASH-fEVs evoked an increase in intestinal permeability in wild type but not in nmMLCK deficient mice. Bacterial origins of fEVs were different between NAFLD and NASH patients and 16 amplicon sequence variants were differentially abundant. We demonstrate that fEVs actively participate in barrier dysfunctions leading to liver injuries underscoring the role of nmMLCK and lipopolysaccharide carried by fEVs.

Serum concentration of fatty acids in children with obesity and nonalcoholic fatty liver disease

OBJECTIVES

It has been suggested that circulating fatty acids (FAs) take part in the pathogenesis of nonalcoholic fatty liver disease (NAFLD) in children with obesity. The aims of this study were to evaluate the serum FA concentration in this pediatric population.

METHODS

The prospective study included 80 children with obesity and suspected liver disease. Patients with viral hepatitis, autoimmune, toxic, and selected metabolic liver diseases were excluded. Criteria for NAFLD diagnosis included liver steatosis in ultrasound as well as elevated alanine transaminase (ALT) serum activity. The total intrahepatic lipid content (TILC) was assessed by magnetic resonance proton spectroscopy (1H-MRS). Fasting serum FA concentrations were measured in all children using gas-liquid chromatography.

RESULTS

NAFLD was diagnosed in 31 children. Total FA concentration was significantly higher (P < 0.01) in all obese children as well as in obese children with NAFLD compared with controls. In children with NAFLD, a significant, positive correlation was found between total FA concentration and cholesterol (R = 0.47, P < 0.01), triacylglycerols (R = 0.78, P < 0.001), and insulin (R = 0.45, P < 0.011). In a group of children with obesity, TILC correlated positively with saturated FA concentration (R = 0.23, P < 0.05).

CONCLUSION

Data from the present study do support the hypothesis that FAs are potentially involved in the pathogenesis of NAFLD in children with obesity.

Label-free quantitative proteomic analysis of serum extracellular vesicles differentiating patients of alcoholic and nonalcoholic fatty liver diseases

Alcoholic liver disease (ALD) and nonalcoholic fatty liver disease (NAFLD) are typically asymptomatic and slow-progressing but potentially fatal diseases that are common causes of liver cirrhosis and related complications. Exosomes are nano-sized extracellular vesicles that have been linked to various intercellular communication processes and can carry biological materials reflecting the state and severity of disease. In this study, shotgun proteomic analysis of the protein expression profiles of extracellular vesicles, including exosomes and microvesicles, enriched from human serum samples of 24 patients diagnosed with various fatty liver diseases was performed using liquid chromatography tandem mass spectrometry (LC-MS/MS) followed by protein identification and label-free quantification using the MaxQuant platform. A total of 329 proteins, including 190 previously reported exosome-specific proteins, were identified from four types of liver disease, where significant differences in protein expression were found in apolipoproteins, immunoglobulins, and other previously reported markers of liver disease. Principal component analysis of 61 proteins identified from MaxQuant analysis of the LC-MS/MS data provided a confident differentiation between ALD and NAFLD. SIGNIFICANCE: The current investigation revealed the difference among various types of liver disease using LC-MS/MS of exosomes enriched from human serum samples of 24 patients where the most significantly up-regulation proteins were alpha-2-macroglobulin for alcoholic hepatitis and apolipoprotein C3 for nonalcoholic fatty liver disease.

Diversity in NAFLD: A Review of Manifestations of Nonalcoholic Fatty Liver Disease in Different Ethnicities Globally

Globally, the rise in prevalence of obesity and metabolic syndrome as a whole has been linked to increased access to processed foods, such as refined sugars and saturated fats. Consequently, nonalcoholic fatty liver disease (NAFLD) is on the rise in both developed and developing nations. However, much is still unknown on the NAFLD phenotype with regards to the effect of ethnic diversity. Despite similarities in dietary habits, it appears that certain ethnicities are more protected against NAFLD than others. However, manifestations of the same genetic polymorphisms in different groups of people increase those individuals' predisposition to NAFLD. Diets from different regions have been associated with a lower prevalence of NAFLD and have even been linked to regression of hepatic steatosis. Socioeconomic variations amongst different regions of the world also contribute to NAFLD prevalence and associated complications. Thus, a thorough understanding of ethnic variability in NAFLD is essential to tailoring treatment recommendations to patients of different backgrounds.

Gut microbiota impact on the peripheral immune response in non-alcoholic fatty liver disease related hepatocellular carcinoma

The gut microbiota is reported to modulate the immune response in hepatocellular carcinoma (HCC). Here, we employ metagenomic and metabolomic studies to characterise gut microbiota in patients with non-alcoholic fatty liver disease (NAFLD) related cirrhosis, with or without HCC, and evaluate its effect on the peripheral immune response in an ex vivo model. We find that dysbiosis characterises the microbiota of patients with NAFLD-cirrhosis, with compositional and functional shifts occurring with HCC development. Gene function of the microbiota in NAFLD-HCC supports short chain fatty acid production, and this is confirmed by metabolomic studies. Ex vivo studies show that bacterial extracts from the NAFLD-HCC microbiota, but not from the control groups, elicit a T cell immunosuppressive phenotype, characterised by expansion of regulatory T cells and attenuation of CD8 + T cells. Our study suggest that the gut microbiota in NAFLD-HCC is characterised by a distinctive microbiome/metabolomic profile, and can modulate the peripheral immune response.

N-glycosylation of CREBH improves lipid metabolism and attenuates lipotoxicity in NAFLD by modulating PPARα and SCD-1

INTRODUCTION

Cyclic adenosine monophosphate (AMP)-responsive element-binding protein H (CREBH), an endoplasmic reticulum-anchored transcription factor essential for lipid metabolism and inflammation in nonalcoholic fatty liver disease (NAFLD), is covalently modified by N-acetylglucosamine. Glycosylation is a ubiquitous type of protein involved in posttranslational modifications, and plays a critical role in various biological processes. However, the mechanism of glycosylated CREBH remains poorly understood in NAFLD.

METHODS

CREBH glycosylation mutants were obtained by site-mutation methods. After transfection with plasmids, AML-12, LO2, or HepG2 cells were treated with palmitic acid (PA) proteolysis, tunicamycin (Tm), or their combination. Glycosyltransferase V (GnT-V) was used induce hyperglycosylation to further understand the effect of CREBH. In addition, glycosylation mutant mice and hyperglycosylated mice were generated by lentivirus injection to construct two kinds of NAFLD animal models. The expression of NAFLD-related factors was detected to further verify the role of N-linked glycosylation of CREBH in lipid and sterol metabolism, inflammation, and lipotoxicity.

RESULTS

N-glycosylation enhanced the ability of CREBH to activate transcription and modulated the production of peroxisome proliferator-activated receptor alpha (PPARα) and stearoyl-CoA desaturase-1 (SCD-1) activity by affecting their promoter-driven transcription activity and protein interactions, leading to reduce lipid deposition and attenuate lipotoxicity. Deglycosylation of CREBH induced by Tm could inhibit the proteolysis of CREBH induced by PA. The addition of unglycosylated CREBH to cells upregulates gene and protein expression of lipogenesis, lipotoxicity, and inflammation, and aggravates liver damage by preventing glycosylation in cells, as well as in mouse models of NAFLD. Furthermore, increased N-glycosylation of CREBH, as achieved by overexpressing GnT-V could significantly improve liver lesion caused by unglycosylation of CREBH.

CONCLUSION

These findings have important implications for the role of CREBH N-glycosylation in proteolytic activation, and they provide the first link between N-glycosylation of CREBH, lipid metabolism, and lipotoxicity processes in the liver by modulating PPARα and SCD-1. These results provide novel insights into the N-glycosylation of CREBH as a therapeutic target for NAFLD.

Health-related Quality of Life in Nonalcoholic Fatty Liver Disease Associates With Hepatic Inflammation

BACKGROUND & AIMS

Chronic liver disease has negative effects on health-related quality of life (HRQL). We analyzed data from the European non-alcoholic fatty liver disease (NAFLD) registry to assess the effects of NAFLD on HRQL.

METHODS

We collected data from 304 patients (mean age, 52.3 ± 12.9 years) with histologically defined NAFLD enrolled prospectively into the European NAFLD Registry in Germany, the United Kingdom, and Spain. The chronic liver disease questionnaire (CLDQ) was completed within 6 months of liver biopsy collection.

RESULTS

The mean CLDQ overall score was 5.0 ± 1.2, with the lowest score in the category fatigue (4.3 ± 1.6) and the highest scores for activity (5.4 ± 1.4). Women had significantly lower CLDQ scores than men (4.6 ± 1.3 vs 5.3 ± 1.1; P < .001). We found negative correlations between CLDQ scores and presence of obesity (P < .001), type 2 diabetes (P < .001), and dyslipidaemia (P < .01). There was a negative correlation between level of aspartate aminotransferase, but not alanine aminotransferase, and HRQL. Higher histological score of steatosis (1 vs 3) resulted in lower mean CLDQ score (5.3 ± 1.1 vs 4.5 ± 1.4; P < .01); higher level of lobular inflammation (0 vs 3) also resulted in lower mean CLDQ score (5.3 ± 1.2 vs 3.9 ± 1.8; P <. 001). In contrast, advanced fibrosis (F3-4) compared to early or intermediate fibrosis (F0-2) had no significant effect on mean CLDQ score (4.9 ± 1.2 vs 5.1 ± 1.3; P = .072). In multivariate analysis, patients sex, age, presence of type 2 diabetes, and inflammation were independently associated with low HRQL.

CONCLUSION

In an analysis of data from the European NAFLD registry, we observed a substantial burden of symptoms in patients. In addition to age, sex, and the presence of diabetes, detection of lobular inflammation in biopsies correlated with lower HRQL.

Deranged hepatocyte intracellular Ca2+ homeostasis and the progression of non-alcoholic fatty liver disease to hepatocellular carcinoma

Hepatocellular carcinoma (HCC) is the second leading cause of cancer-related deaths in men, and the sixth in women. Non-alcoholic fatty liver disease (NAFLD) is now one of the major risk factors for HCC. NAFLD, which involves the accumulation of excess lipid in cytoplasmic lipid droplets in hepatocytes, can progress to non-alcoholic steatosis, fibrosis, and HCC. Changes in intracellular Ca²⁺ constitute important signaling pathways for the regulation of lipid and carbohydrate metabolism in normal hepatocytes. Recent studies of steatotic hepatocytes have identified lipid-induced changes in intracellular Ca²⁺, and have provided evidence that altered Ca²⁺ signaling exacerbates lipid accumulation and may promote HCC. The aims of this review are to summarise current knowledge of the lipid-induced changes in hepatocyte Ca²⁺ homeostasis, to comment on the mechanisms involved, and discuss the pathways leading from altered Ca²⁺ homeostasis to enhanced lipid accumulation and the potential promotion of HCC. In steatotic hepatocytes, lipid inhibits store-operated Ca²⁺ entry and SERCA2b, and activates Ca²⁺ efflux from the endoplasmic reticulum (ER) and its transfer to mitochondria. These changes are associated with changes in Ca²⁺ concentrations in the ER (decreased), cytoplasmic space (increased) and mitochondria (likely increased). They lead to: inhibition of lipolysis, lipid autophagy, lipid oxidation, and lipid secretion; activation of lipogenesis; increased lipid; ER stress, generation of reactive oxygen species (ROS), activation of Ca²⁺/calmodulin-dependent kinases and activation of transcription factor Nrf2. These all can potentially mediate the transition of NAFLD to HCC. It is concluded that lipid-induced changes in hepatocyte Ca²⁺ homeostasis are important in the initiation and progression of HCC. Further research is desirable to better understand the cause and effect relationships, the time courses and mechanisms involved, and the potential of Ca²⁺ transporters, channels, and binding proteins as targets for pharmacological intervention.

Increased serum concentration of ceramides in obese children with nonalcoholic fatty liver disease

Background

Hepatic lipid accumulation is closely related to the development of insulin resistance, which is regarded as one of the most significant risk factors of nonalcoholic fatty liver disease (NAFLD). Although the exact molecular pathway leading to impaired insulin signaling has not been definitively established, ceramides are suspected mediators of lipid induced hepatic insulin resistance. Therefore, the aim of the study was to evaluate the serum ceramides concentration in obese children with NAFLD.

Methods

The prospective study included 80 obese children (aged 7–17 years, median 12 years) admitted to our Department to diagnose initially suspected liver disease. Patients with viral hepatitis (HCV, HBV, CMV), autoimmune (AIH), toxic and metabolic (Wilson’s disease, alfa-1–antitrypsin deficiency) liver diseases and celiac disease were excluded. NAFLD was diagnosed based on pediatric diagnostic criteria in obese children with liver steatosis in ultrasound (US) as well as elevated alanine transaminase (ALT) serum activity after exclusion of other major liver diseases listed before. Ultrasonography was used as a screening method and for qualitative assessment of the steatosis degree (graded according to Saverymuttu scale). Advanced steatosis was defined as a score > 1. The total intrahepatic lipid content (TILC) was assessed by magnetic resonance proton spectroscopy (¹HMRS) which is the most accurate technique for assessment of ectopic fat accumulation. Fasting serum concentration of ceramides was measured in 62 children.

Results

NAFLD was diagnosed in 31 children. Significant, positive correlation was found between total serum concentration of ceramides and insulin (r = 0.3, p = 0.02) and HOMA-IR (r = 0.28, p = 0.03). Total ceramide concentration as well as specific fatty acid-ceramides (FA-ceramides) concentrations, namely: myristic, palmitic, palmitoleic, stearic, oleic, behenic and lignoceric were significantly higher (p = 0.004, p = 0.003, p = 0.007, p < 0.001, p = 0.035, p = 0.008, p = 0.003, p = 0.006, respectively) in children with NAFLD compared to controls (n = 14). Moreover, children with NAFLD had significantly higher activity of ALT (p < 0.001) and GGT (p < 0.001), HOMA-IR (p = 0.04), BMI (p = 0.046), waist circumference (p = 0.01) steatosis grade in ultrasound (p < 0.001) and TILC in ¹HMRS (p < 0.001) compared to children without NAFLD. We did not find significant differences in total and FA-ceramide species concentrations between children with mild (grade 1) and advanced liver steatosis in ultrasonography (grade 2–3).

Conclusion

Elevated ceramide concentrations in obese patients together with their significant correlation with insulin resistance parameters suggest their association with molecular pathways involved in insulin signaling impairment known to be strongly linked to pathogenesis of non-alcoholic fatty liver disease.