Increased hepatic and circulating chemokine and osteopontin expression occurs early in human NAFLD development

Role of Cardiac Biomarkers in Hepatic Disorders: A Literature Review

Various studies have reported the association between cardiac markers and hepatic disorders. The main objective of this review article was to elucidate the significance of important cardiac indicators such as ischemia-modified albumin, cardiac troponin, cardiac natriuretic peptides, creatine kinase, creatine kinase-MB, lactate dehydrogenase, heart-type fatty acid-binding protein, osteopontin, soluble suppression of tumorigenicity 2, C-reactive protein, and lipoprotein(a) in the development of hepatic disorders. In addition, it highlighted recent notable discoveries and accomplishments in this field and identified areas requiring further investigation, ongoing discussions, and potential avenues for future research. Early identification and control of these cardiac markers might be helpful to control the prevalence of hepatic disorders associated with cardiovascular diseases.

GW9662 ameliorates nonalcoholic steatohepatitis by inhibiting the PPARγ/CD36 pathway and altering the gut microbiota

BACKGROUND & AIMS

Peroxisome proliferator-activated receptors (PPARs) are currently among the most focused-on therapeutic targets for non-alcoholic steatohepatitis (NASH), although no clinical transformation has been achieved to date. In this study, we aimed to evaluate the effects of GW9662 on choline-deficient, L-amino acid-defined high-fat diet (CDAA-HFD)-induced NASH mice and reveal the mechanism underlying this effect.

METHODS

GW9662 (1 mg/kg) was administered in CDAA-HFD mouse model of NASH. The effect of GW9662 on hepatic lipid metabolism was investigated using liver RNA-seq and HepG2 cells induced by oleic acid and palmitic acid. In addition, 16S rRNA gene sequencing was performed to analyze the effects of GW9662 on the composition and function of the fecal microbiota.

RESULTS

GW9662 improved the CDAA-HFD caused elevation in the levels of ALT, AST, hepatic free fatty acids and triglycerides. The liver pathological analysis indicated that GW9662 alleviated the hepatic steatosis and fibrosis. The NAFLD activity score and RNA-Seq revealed that GW9662 mainly regulated the fatty acids transport and lipid synthesis by inhibiting PPARγ, CD36, FABP1, FASN, and SCD1, and through the up-regulation of PPARα. Moreover, GW9662 reduced the epididymal fat weight. GW9662 reversed the gut microbiota disorder by increasing the abundance of the beneficial bacteria Dubosiella and Lactobacillus and decreasing the abundance of harmful bacteria Lachnospiraceae_NK4A136_group, Helicobacteraceae, Desulfovibriaceae, and Rickenaceae.

CONCLUSIONS

GW9662 ameliorated lipid metabolism by inhibiting the PPARγ/CD36 pathway and altering the composition of the gut microbiota in NASH mice. Therefore, the PPARγ antagonist GW9662 deserves more attention as a potential therapeutic agent for NASH.

Overview of hepatocellular carcinoma: from molecular aspects to future therapeutic options

Hepatocellular carcinoma (HCC) is the seventh most highly prevalent malignant tumor globally and the second most common cause of mortality. HCC develops with complex pathways that occur through multistage biological processes. Non-alcoholic fatty liver disease, metabolic-associated fatty liver disease, alcoholic liver disease, autoimmune hepatitis, hepatitis B, and hepatitis C are the causative etiologies of HCC. HCC develops as a result of epigenetic changes, protein-coding gene mutations, and altered signaling pathways. Biomarkers and potential therapeutic targets for HCC open up new possibilities for treating the disease. Immune checkpoint inhibitors are included in the treatment options in combination with molecular targeted therapy.

Macrophage-associated markers of metaflammation are linked to metabolic dysfunction in pediatric obesity

BACKGPOUND

Metabolically driven chronic low-grade adipose tissue inflammation, so-called metaflammation, is a central feature in obesity. This inflammatory tone is largely driven by adipose tissue macrophages (ATM), which express pro- and anti-inflammatory markers and cytokines such as, e.g., IL-1 receptor antagonist (IL-1RA), CD163 and osteopontin (OPN). Metaflammation ultimately leads to the development of cardiometabolic diseases. This study aimed to evaluate the association between selected adipose tissue macrophage-associated markers and metabolic comorbidities in pediatric obesity.

METHODS

From a pediatric cohort with obesity (n = 108), clinically thoroughly characterized including diverse routine blood parameters, oral glucose tolerance test and liver MRI, plasma IL-1RA, soluble (s)CD163 and OPN were measured by ELISA.

RESULTS

We observed significantly higher IL-1RA, sCD163, and OPN levels in the plasma of children with metabolic-dysfunction associated fatty liver disease (MAFLD) and metabolic syndrome. Moreover, IL-1RA and sCD163 correlated with hepatic disease and apoptosis markers alanine aminotransferase and CK-18. IL-1RA concentrations additionally correlated with insulin resistance, while children with disturbed glucose metabolism had significantly higher levels of sCD163.

CONCLUSION

MAFLD and other metabolic disorders in pediatric patients with obesity are associated with an elevation of adipose tissue macrophage-related inflammation markers.

Sex-Dependent Hepatoprotective Role of IL-22 Receptor Signaling in Non-Alcoholic Fatty Liver Disease-Related Fibrosis

BACKGROUND & AIMS

Nonalcoholic fatty liver disease (NAFLD) is a major health problem with complex pathogenesis. Although sex differences in NAFLD pathogenesis have been reported, the mechanisms underlying such differences remain understudied. Interleukin (IL)22 is a pleiotropic cytokine with both protective and/or pathogenic effects during liver injury. IL22 was shown to be hepatoprotective in NAFLD-related liver injury. However, these studies relied primarily on exogenous administration of IL22 and did not examine the sex-dependent effect of IL22. Here, we sought to characterize the role of endogenous IL22-receptor signaling during NAFLD-induced liver injury in males and females.

METHODS

We used immunofluorescence, flow cytometry, histopathologic assessment, and gene expression analysis to examine IL22 production and characterize the intrahepatic immune landscape in human subjects with NAFLD (n = 20; 11 men and 9 women) and in an in vivo Western high-fat diet-induced NAFLD model in IL22RA knock out mice and their wild-type littermates.

RESULTS

Examination of publicly available data sets from 2 cohorts with NAFLD showed increased hepatic IL22 gene expression in females compared with males. Furthermore, our immunofluorescence analysis of liver sections from NAFLD subjects (n = 20) showed increased infiltration of IL22-producing cells in females. Similarly, IL22-producing cells were increased in wild-type female mice with NAFLD and the hepatic IL22/IL22 binding protein messenger RNA ratio correlated with expression of anti-apoptosis genes. The lack of endogenous IL22-receptor signaling (IL22RA knockout) led to exacerbated liver damage, inflammation, apoptosis, and liver fibrosis in female, but not male, mice with NAFLD.

CONCLUSIONS

Our data suggest a sex-dependent hepatoprotective antiapoptotic effect of IL22-receptor signaling during NAFLD-related liver injury in females.

Identification of the Non-Alcoholic Fatty Liver Disease Molecular Subtypes Associated With Clinical and Immunological Features via Bioinformatics Methods

Background

Non-alcoholic fatty liver disease (NAFLD) is a manifestation of metabolic syndrome in the liver with varying severity. Heterogeneity in terms of molecules and immune cell infiltration drives NAFLD from one stage to the next. However, a precise molecular classification of NAFLD is still lacking, and the effects of complex clinical phenotypes on the efficacy of drugs are usually ignored.

Methods

We introduced multiple omics data to differentiate NAFLD subtypes via consensus clustering, and a weighted gene co-expression network analysis was used to identify eight co-expression modules. Further, eigengenes of eight modules were analyzed with regard to Gene Ontology enrichment and Kyoto Encyclopedia of Genes and Genomes pathways. Furthermore, the infiltration rates of 22 immune cell types were calculated with CIBERSORT and the ESTIMATE algorithm.

Results

In total, 111 NAFLD patients from three independent GEO datasets were divided into four molecular subtypes, and the corresponding clinical features and immune cell infiltration traits were determined. Based on high gene expression correlations, four molecular subtypes were further divided into eight co-expression modules. We also demonstrated a significant correlation between gene modules and clinical phenotypes. Moreover, we integrated phenotypic, immunologic, and genetic data to assess the potential for progression of different molecular subtypes. Furthermore, the efficacy of drugs against various NAFLD molecular subtypes was discussed to aid in individualized therapy.

Conclusion

Overall, this study could provide new insights into the underlying pathogenesis of and drug targets for NAFLD.

MD2 deficiency prevents high-fat diet-induced AMPK suppression and lipid accumulation through regulating TBK1 in non-alcoholic fatty liver disease

BACKGROUND

Non-alcoholic fatty liver disease (NAFLD) is the most predominant form of liver diseases worldwide. Recent evidence shows that myeloid differentiation factor 2 (MD2), a protein in innate immunity and inflammation, regulates liver injury in models of NAFLD. Here, we investigated a new mechanism by which MD2 participates in the pathogenesis of experimental NAFLD.

METHODS

Wild-type, Md2-/- and bone marrow reconstitution mice fed with high-fat diet (HFD) were used to identify the role of hepatocyte MD2 in NAFLD. Transcriptomic RNA-seq and pathway enrich analysis were performed to explore the potential mechanisms of MD2. In vitro, primary hepatocytes and macrophages were cultured for mechanistic studies.

RESULTS

Transcriptome analysis and bone marrow reconstitution studies showed that hepatocyte MD2 may participate in regulating lipid metabolism in models with NAFLD. We then discovered that Md2 deficiency in mice prevents HFD-mediated suppression of AMP-activated protein kinase (AMPK). This preservation of AMPK in Md2-deficient mice was associated with normalized sterol regulatory element binding protein 1 (SREBP1) transcriptional program and a lack of lipid accumulation in both hepatocytes and liver. We then showed that hepatocyte MD2 links HFD to AMPK/SREBP1 through TANK binding kinase 1 (TBK1). In addition, MD2-increased inflammatory factor from macrophages induces hepatic TBK1 activation and AMPK suppression.

CONCLUSION

Hepatocyte MD2 plays a pathogenic role in NAFLD through TBK1-AMPK/SREBP1 and lipid metabolism pathway. These studies provide new insight into a non-inflammatory function of MD2 and evidence for the important role of MD2 in NALFD.

Machine Learning-Based Identification of Potentially Novel Non-Alcoholic Fatty Liver Disease Biomarkers

Non-alcoholic fatty liver disease (NAFLD) is a chronic liver disease that presents a great challenge for treatment and prevention.. This study aims to implement a machine learning approach that employs such datasets to identify potential biomarker targets. We developed a pipeline to identify potential biomarkers for NAFLD that includes five major processes, namely, a pre-processing step, a feature selection and a generation of a random forest model and, finally, a downstream feature analysis and a provision of a potential biological interpretation. The pre-processing step includes data normalising and variable extraction accompanied by appropriate annotations. A feature selection based on a differential gene expression analysis is then conducted to identify significant features and then employ them to generate a random forest model whose performance is assessed based on a receiver operating characteristic curve. Next, the features are subjected to a downstream analysis, such as univariate analysis, a pathway enrichment analysis, a network analysis and a generation of correlation plots, boxplots and heatmaps. Once the results are obtained, the biological interpretation and the literature validation is conducted over the identified features and results. We applied this pipeline to transcriptomics and lipidomic datasets and concluded that the C4BPA gene could play a role in the development of NAFLD. The activation of the complement pathway, due to the downregulation of the C4BPA gene, leads to an increase in triglyceride content, which might further render the lipid metabolism. This approach identified the C4BPA gene, an inhibitor of the complement pathway, as a potential biomarker for the development of NAFLD.

Construction and analysis of protein-protein interaction network of non-alcoholic fatty liver disease

Non-alcoholic fatty liver disease (NAFLD) is a disease with multidimensional complexities. Many attempts have been made over the years to treat this disease but its incidence is rising. For this reason, the need to identify and study new candidate proteins that may be associated with NAFLD is of utmost importance. Systems-based approaches such as the analysis of protein-protein interaction (PPI) network could lead to the discovery of new proteins associated with a disease that can then be translated into clinical practice. The aim of this study is to analyze the interaction network of human proteins associated with NAFLD as well as their experimentally verified interactors and to identify novel associations with other human proteins that may be involved in this disease. Computational analysis made it feasible to detect 77 candidate proteins associated with NAFLD, having high network scores. Furthermore, clustering analysis was performed to identify densely connected regions with biological significance in this network. Additionally, gene expression analysis was conducted to validate part of the findings of this research work. We believe that our research will be helpful in extending experimental efforts to address the pathogenesis and progression of NAFLD.

Genomics of Human Fibrotic Diseases: Disordered Wound Healing Response

Fibrotic disease, which is implicated in almost half of all deaths worldwide, is the result of an uncontrolled wound healing response to injury in which tissue is replaced by deposition of excess extracellular matrix, leading to fibrosis and loss of organ function. A plethora of genome-wide association studies, microarrays, exome sequencing studies, DNA methylation arrays, next-generation sequencing, and profiling of noncoding RNAs have been performed in patient-derived fibrotic tissue, with the shared goal of utilizing genomics to identify the transcriptional networks and biological pathways underlying the development of fibrotic diseases. In this review, we discuss fibrosing disorders of the skin, liver, kidney, lung, and heart, systematically (1) characterizing the initial acute injury that drives unresolved inflammation, (2) identifying genomic studies that have defined the pathologic gene changes leading to excess matrix deposition and fibrogenesis, and (3) summarizing therapies targeting pro-fibrotic genes and networks identified in the genomic studies. Ultimately, successful bench-to-bedside translation of observations from genomic studies will result in the development of novel anti-fibrotic therapeutics that improve functional quality of life for patients and decrease mortality from fibrotic diseases.