Paediatric non-alcoholic fatty liver disease: an approach to pathological evaluation

M6A methyltransferase METTL3 promotes glucose metabolism hub gene expression and induces metabolic dysfunction-associated steatotic liver disease (MASLD)

BACKGROUND

N6-methyladenosine (m6A) RNA modification plays a crucial role in various biological events and is implicated in various metabolic-related diseases. However, its role in MASLD remains unclear. This study aims to investigate the impact of METTL3 on MASLD through multi-omics analysis, with a focus on exploring its potential mechanisms of action.

METHODS

An MASLD mouse model was established by feeding C57BL/6J mice a high-fat diet for 12 weeks. A METTL3 stable overexpression AML12 cell model was also constructed via lentiviral transfection. Subsequent transcriptomic and proteomic analyses, as well as integrated analysis between different omics datasets, were conducted.

RESULTS

METTL3 expression was significantly increased in the MASLD mouse model. Through our transcriptomic and proteomic analyses, we identified 848 genes with significant inconsistencies between the transcriptomic and proteomic datasets. GO/ KEGG enrichment analyses identified terms that may be involved in post-transcriptional modifications, particularly METTL3-mediated m6A modification. Subsequently, through integrated proteomic analysis of the METTL3-overexpressed AML12 cell model and the MASLD mouse model, we selected the top 20 co-upregulated and co-downregulated GO/ KEGG terms as the main biological processes influenced by METTL3 during MASLD. By intersecting with pathways obtained from previous integrated analyses, we identified GO/ KEGG terms affected by METTL3-induced m6A modification. Protein-protein interaction analysis of proteins involved in these pathways highlighted GAPDH and TPI1 as two key hub genes.

CONCLUSIONS

During MASLD, METTL3 regulates the glycolytic pathway through m6A modification, influencing the occurrence and development of the disease via the key hub genes GAPDH and TPI1. These findings expand our understanding of MASLD and provide strong evidence for potential therapeutic targets and drug development.

The effect of orlistat in the treatment of non-alcoholic fatty liver in adolescents with overweight and obese

Nonalcoholic fatty liver disease (NAFLD), which can manifest as nonalcoholic steatohepatitis (NASH) or severe fibrosis, is the most prevalent chronic liver disease in children and adolescents. However, there is no proven cure for it so far. This study was conducted to determine whether adolescents with NAFLD would improve with treatment intervention with orlistat. This study is a randomized controlled trial (RCT). Fifty-three adolescents with overweight/obese as well as with NAFLD randomly allocated to receive orlistat (n = 27) or placebo as control (n = 26) for 12 weeks. In addition, NAFLD activity score, anthropometric factors, biochemical parameters including serum levels of lipid profiles, liver enzyme, and glucose metabolism taken from subjects at baseline and end of the study were investigated. The findings of our article indicated that orlistat improves liver enzymes (alanine transaminase and aspartate transaminase) (P =  < 0.001), steatosis score (P = 0.001), NAFLD activity score (P =  < 0.001), weight (P =  < 0.001), body mass index (BMI) (P =  < 0.001), waist circumferences (WC) (P =  < 0.001), BMI-Z score (P =  < 0.001), glucose metabolism (P = 0.001), total cholesterol (TC) (P = 0.009), low density lipoprotein-cholesterol (LDL) (P =  < 0.001), and high density lipoprotein-cholesterol HDL levels (P = 0.014) compared to the control group after adjusting for possible confounders for 12 weeks. However, no significant changes were observed on triglyceride (TG) following intake of orlistat compared to placebo after adjusting for confounders.

CONCLUSION

The findings of our study reported that orlistat improved NAFLD-related factors and metabolic syndrome-related factors compared to placebo for 12 weeks.

TRIAL REGISTRATION

(Clinical trial registry number: IRCT20220409054467N2, with a registration date of 2022-05-13).

WHAT IS KNOWN

• Among the interventions of interest for the management of pediatric NAFLD, we can mention lifestyle and pharmaceutical measures.

WHAT IS NEW

• This study was conducted to determine whether adolescents with NAFLD would improve with treatment intervention with orlistat. • The findings of our study reported that orlistat improved NAFLD-related factors and metabolic syndrome-related factors compared to placebo for 12 weeks.

Liver Biopsy Handling of Metabolic-Associated Fatty Liver Disease (MAFLD): the Children's Hospital of Eastern Ontario grossing protocol

Metabolic-(non-alcoholic) associated fatty liver disease (MAFLD/NAFLD) has increasingly become a worldwide epidemic. It has been suggested that renaming NAFLD to MAFLD is critical in identifying patients with advanced fibrosis and poor cardiovascular outcomes. There are concerns that the progression to non-alcoholic steatohepatitis (NASH) may become a constant drive in the future healthcare of children and adolescents. There is a necessity to tackle the emerging risk factors for NASH-associated hepatocellular carcinoma (HCC). In this narrative review, we present the current protocol of liver biopsy separated between pre-analytical, analytical, and post-analytical handling. Genetic association investigations have identified single nucleotide polymorphisms implicated in the progression of MAFLD-HCC, many of which seem to belong to the lipid metabolism pathways. PNPLA3 rs738409 variant, TM6SF2 rs58542926 variant, MBOAT7 rs641738 variant, and GCKR variants seem to be significantly associated with NAFLD disease susceptibility. In disclosing the current comprehensive protocol performed at the Children's Hospital of Eastern Ontario, Ottawa, ON, Canada, we support the most recent Kulkarni-Sarin's pledge to rename NAFLD to MAFLD. Grossing of the liver biopsy is key to identifying histologic, immunophenotypical, and ultrastructure data and properly preserving tissue for molecular genomics data.

The bidirectional immune crosstalk in metabolic dysfunction-associated steatotic liver disease

Metabolic dysfunction-associated steatotic liver disease (MASLD) is an unabated risk factor for end-stage liver diseases with no available therapies. Dysregulated immune responses are critical culprits of MASLD pathogenesis. Independent contributions from either the innate or adaptive arms of the immune system or their unidirectional interplay are commonly studied in MASLD. However, the bidirectional communication between innate and adaptive immune systems and its impact on MASLD remain insufficiently understood. Given that both innate and adaptive immune cells are indispensable for the development and progression of inflammation in MASLD, elucidating pathogenic contributions stemming from the bidirectional interplay between these two arms holds potential for development of novel therapeutics for MASLD. Here, we review the immune cell types and bidirectional pathways that influence the pathogenesis of MASLD and highlight potential pharmacologic approaches to combat MASLD based on current knowledge of this bidirectional crosstalk.

Special Population: Pediatric Nonalcoholic Fatty Liver Disease

Pediatric nonalcoholic fatty liver disease represents the most common liver disease in children and has been shown to carry significant morbidity. Widespread heterogeneity of disease, as well as the limitation of indirect screening modalities, has made true prevalence of disease difficult to estimate as well as hindered ability to identify optimal prognostic factors in the pediatric population. Current therapeutic options are limited in pediatric patients with current mainstay of therapy, lifestyle modifications, has proven to have a limited efficacy in current clinical application. Current research remains needed in improved screening modalities, prognosticating techniques, and therapeutic options in the pediatric population.