Altered amino acid concentrations in NAFLD: Impact of obesity and insulin resistance

Alterations in hepatic amino acid metabolism related to MASLD in individuals with obesity

Deregulation of amino acid (AA) metabolism has been reported in several pathological conditions, including metabolic diseases (e.g., obesity and diabetes), cardiovascular diseases, and cancer. However, the role of alterations in AA levels in chronic liver disorders such as metabolic dysfunction-associated steatotic liver disease (MASLD) remains largely unexplored. In this study we aimed to evaluate the hepatic AA composition in patients with different stages of MASLD, and their relationship with MASLD-related risk factors. A case-control study was conducted in 40 patients with obesity undergoing bariatric surgery at Virgen de la Arrixaca University Hospital (Murcia, Spain), where MASLD diagnosis was confirmed by histological analysis of liver biopsies, and hepatic AA levels were measured using ultra-performance liquid chromatography high-resolution time-of-flight mass spectrometry. Our results revealed that the hepatic AA profile was significantly altered in patients with MASLD. More specifically, comparison between MASLD patients revealed a significant increase in hepatic levels of arginine, glycine and cystine in MASH samples compared to steatotic livers. In addition, hepatic concentrations of arginine, lysine and cystine positively correlated with histopathological diagnosis and other MASLD-related parameters, including transaminases and CK-18 levels. These findings suggest that alterations in certain hepatic AA levels such as arginine, lysine, glycine and cystine in MASLD patients could have translational relevance in understanding the onset of this disease.

A metabolome-derived score predicts metabolic dysfunction-associated steatohepatitis and mortality from liver disease

BACKGROUND & AIMS

Metabolic dysfunction-associated steatohepatitis (MASH) is associated with a >10-fold increase in liver-related mortality. However, biomarkers predicting both MASH and mortality in patients with metabolic dysfunction-associated steatotic liver disease (MASLD) are missing. We developed a metabolome-derived prediction score for MASH and examined whether it predicts mortality in Chinese and European cohorts.

METHODS

The MASH prediction score was developed using a multi-step machine learning strategy, based on 44 clinical parameters and 250 serum metabolites measured by proton nuclear magnetic resonance in 311 Chinese adults undergoing a liver biopsy. External validation was conducted in a Finnish liver biopsy cohort (n = 305). We investigated associations of the score with all-cause and cause-specific mortality in the population-based Shanghai Changfeng study (n = 5,893) and the UK biobank (n = 111,673).

RESULTS

A total of 24 clinical parameters and 194 serum metabolites were significantly associated with MASH in the Chinese liver biopsy cohort. The final MASH score included BMI, aspartate aminotransferase, tyrosine, and the phospholipid-to-total lipid ratio in VLDL. The score identified patients with MASH with AUROCs of 0.87 (95% CI 0.83-0.91) and 0.81 (95% CI 0.75-0.88) in the Chinese and Finnish cohorts, with high negative predictive values. Participants with a high or intermediate risk of MASH based on the score had a markedly higher risk of MASLD-related mortality than those with a low risk in Chinese (hazard ratio 23.19; 95% CI 4.80-111.97) and European (hazard ratio 20.15; 95% CI 10.95-37.11) individuals after 7.2 and 12.6 years of follow-up, respectively. The MASH prediction score was superior to the Fibrosis-4 index and the NAFLD fibrosis score in predicting MASLD-related mortality.

CONCLUSION

The metabolome-derived MASH prediction score accurately predicts risk of MASH and MASLD-related mortality in both Chinese and European individuals.

IMPACT AND IMPLICATIONS

Metabolic dysfunction-associated steatohepatitis (MASH) is associated with more than a 10-fold increase in liver-related death. However, biomarkers predicting not only MASH, but also death due to liver disease, are missing. We established a MASH prediction score based on 44 clinical parameters and 250 serum metabolites using a machine learning strategy. This metabolome-derived MASH prediction score could accurately identify patients with MASH among both Chinese and Finnish individuals, and it was superior to the Fibrosis-4 index and the NAFLD fibrosis score in predicting MASLD-related death in the general population. Thus, the new MASH prediction score is a useful tool for identifying individuals with a markedly increased risk of serious liver-related outcomes among at-risk and general populations.

Mechanistic Study of the Deuterium Effect in Chromatographic Separation for Chemical-Tagging Metabolomics and Its Application to Biomarker Discovery in Metabolic Dysfunction-Associated Steatohepatitis

Over the past decade, numerous metabolomics techniques have been developed using liquid chromatography-mass spectrometry (LC-MS). These methodologies have yielded significant findings and facilitated the identification of biomarkers. Among these, chemical-tagging methodologies combined with isotope surrogate tags have garnered considerable attention as a leading approach. Chemical-tagging reduces labor and costs by eliminating the need for internal standard preparation. However, the chromatographic deuterium effect (CDE) has persisted as a significant challenge. CDE poses a risk of data misinterpretation in metabolomics due to potential differences in matrix effects. Although the CDE mechanism has been partially elucidated, it has primarily been attributed to differences in hydrophobicity. A detailed understanding of CDE mechanisms would be valuable for designing chemical tags and optimizing liquid chromatography (LC) conditions. Moreover, emphasizing the CDE could aid in the separation and purification of deuterated compounds. In this study, we investigated the mechanistic basis of the CDE. Initially, four chromatography columns with different separation modes─octadecyl, octadecyl with a positively charged surface, biphenyl, and pentafluorophenyl (PFP) groups─were evaluated based on retention differences between 1H- and 2H6-labeled chemically tagged metabolites. Among these, the PFP column demonstrated the most effective reduction of the CDE, suggesting that electronic interactions with fluorine stabilized 2H-labeled metabolites. Further optimization using the PFP column showed its efficacy in reducing the level of CDE in human serum samples. Finally, the optimized approach was successfully applied to global metabolomics analysis of serum from a mouse model of metabolic dysfunction-associated steatohepatitis.

Endogenous Metabolites in Metabolic Diseases: Pathophysiologic Roles and Therapeutic Implications

Breakthroughs in metabolomics technology have revealed the direct regulatory role of metabolites in physiology and disease. Recent data have highlighted the bioactive metabolites involved in the etiology and prevention and treatment of metabolic diseases such as obesity, nonalcoholic fatty liver disease, type 2 diabetes mellitus, and atherosclerosis. Numerous studies reveal that endogenous metabolites biosynthesized by host organisms or gut microflora regulate metabolic responses and disorders. Lipids, amino acids, and bile acids, as endogenous metabolic modulators, regulate energy metabolism, insulin sensitivity, and immune response through multiple pathways, such as insulin signaling cascade, chemical modifications, and metabolite-macromolecule interactions. Furthermore, the gut microbial metabolites short-chain fatty acids, as signaling regulators have a variety of beneficial impacts in regulating energy metabolic homeostasis. In this review, we will summarize information about the roles of bioactive metabolites in the pathogenesis of many metabolic diseases. Furthermore, we discuss the potential value of metabolites in the promising preventive and therapeutic perspectives of human metabolic diseases.

Metabolome profiling across liver lobes and metabolic shifts of the MASLD mice

BACKGROUND

The mammalian liver executes its vital functions through intricate hepatic biochemistry. However, the complexity of the liver metabolome and its dynamic alterations during metabolic dysfunction-associated steatotic liver disease (MASLD) remain poorly understood.

METHODS

We established progressive MASLD mouse models through high-fat diet (HFD) and high-fat/high-cholesterol (HFHC) dietary-feeding across multiple time points. Utilizing liquid chromatography-mass spectrometry (LC-MS)-based metabolomics and lipidomics, we systematically mapped the metabolome atlas of the mouse liver across five anatomical segments during the progression of MASLD.

RESULTS

By integration of data from two assays, we structurally annotated 426 lipids and 118 polar metabolites. The temporal progression of HFD feeding (0, 8, and 16 weeks) resulted in gradual metabolic deterioration across various liver segments. In HFHC-fed mice, metabolic alterations surged sharply from 0 to 8 weeks, followed by moderate progression until 16 weeks in different liver segments. Elevated levels of glycerolipids and cholesteryl esters, along with fluctuating acylcarnitine and fatty acid levels across various liver segments, suggested impaired energy metabolism and disrupted fatty acid oxidation. As MASLD progresses, a shift in sphingolipid metabolism, linked to inflammation, was observed, accompanied by significant alterations in phospholipid turnover patterns. Additionally, amino acid profiles in the livers of HFD-fed and HFHC-fed mice were altered, potentially influencing the regulation of energy metabolism, inflammation, and oxidative stress. These metabolic changes in lipids and amino acids displayed segment-specific patterns, indicating varying sensitivities to inflammation and mitochondrial β-oxidation across different liver lobes. Notably, the left lateral lobe showed heightened sensitivity to metabolic disturbances during MASLD progression.

CONCLUSION

Our findings provided in-depth understanding in hepatic metabolites of MASLD, offering a comprehensive resource for further investigation.

RAP1A suppresses hepatic steatosis by regulating amino acid-mediated mTORC1 activation

Background & Aims

Metabolic dysfunction-associated steatotic liver disease (MASLD) is characterized by triglyceride (TG) build-up in hepatocytes; however, our understanding of the underlying molecular mechanisms is limited. Here, we investigated the role of hepatic GTPase RAP1A in MASLD and its more progressive form, metabolic dysfunction-associated steatohepatitis (MASH).

Methods

RAP1A was silenced or activated by AAV8-TBG-mediated gene expression or treating mice with a small molecule RAP1 activator (n = 4-12 per group). Primary hepatocytes were used to further probe the newly elucidated pathway. Liver samples from patients with MASH and control livers were analyzed for active RAP1A levels (n = 4 per group).

Results

Activation of hepatic RAP1A is suppressed in obese mice with MASLD and restoring its activity decreases liver steatosis. RAP1A activation lowers hepatic TG accumulation through decreasing sterol regulatory element-binding protein 1 (SREBP1) cleavage by inhibiting the mechanistic target of rapamycin complex 1 (mTORC1). The mechanism linking RAP1A activation to suppression of mTORC1 involves the lowering of membrane-bound amino acid transporters, which leads to reduced hepatocyte amino acid uptake, decreased intracellular amino acid levels, and inhibition of amino acid-mediated mTORC1 activation. Furthermore, we observed that active-RAP1A levels were decreased in mice fed a MASH-provoking diet (98% lower, p <0.01) and liver extracts from patients with MASH (86% lower, p <0.05). Accordingly, restoration of RAP1A activity in mice liver lowered liver fibrotic gene expression and prevented fibrosis formation, whereas RAP1A silencing promoted the progression of MASH.

Conclusions

Activation of hepatic RAP1A lowers MASLD and MASH formation by suppressing amino acid-mediated mTORC1 activation and decreasing cleaved SREBP1. These data provide mechanistic insight into amino acid-mediated mTORC1 regulation and raise the possibility that hepatic RAP1A may serve as a mechanistic node linking obesity with MASLD and MASH.

Impact and implications

Metabolic dysfunction-associated liver pathologies are inadequately treated with currently available therapy. Here we demonstrate that the small GTPase RAS-associated protein 1A (RAP1A) protects against liver steatosis and fibrosis development by decreasing hepatocyte amino acid levels, which results in lower mTORC1 activity and SREBP1 cleavage. The results may present new targets against metabolic dysfunction related liver diseases.

Investigation of pH-dependent 1H NMR urine metabolite profiles for diagnosis of obesity-related disordering

BACKGROUND

Human urine is highly favorable for 1H NMR metabolomics analyses of obesity-related diseases, such as non-alcoholic fatty liver, type 2 diabetes, and hyperlipidemia (HL), due to its non-invasiveness and ease of large-scale collection. However, the wide range of intrinsic urine pH (5.5-8.5) results in inevitably chemical shift and signal intensity modulations in the 1H NMR spectra. For patients where acidic urine pH is closely linked to obesity-related disease phenotypes, the pH-dependent modulations complicate the spectral analysis and deteriorate quantifications of urine metabolites.

METHODS

We characterized human urine metabolites by NMR at intrinsic urine pH, across urine pH 4.5 to 9.5, to account for pH-dependent modulations. A pH-dependent chemical shift database for quantifiable urine metabolites was generated and integrated into a "pH intelligence" program developed for quantifications of pH-dependent modulations at various pH. The 1H NMR spectra of urines collected from patients with Ob-HL and healthy controls were compared to uncover potential metabolic biomarkers of Ob-HL disease.

RESULTS

Three urine metabolites were unveiled by pH-dependent NMR approach, i.e., TMAO, glycine, and pyruvic acid, with VIP score >1.0 and significant q-value < 0.05, that represent as potential biomarkers for discriminating Ob-HL from healthy controls. Further ROC-AUC analyses revealed that TMAO alone achieved the highest diagnostic accuracy (AUC 0.902), surpassed to that obtained by neutralizing pH approach (AUC 0.549) and enabled better recovering potential urine metabolites from the Ob-HL disease phenotypes.

CONCLUSIONS

We concluded that 1H NMR-derived urine metabolite profile represents a snapshot that can reveal the physiological condition of humans in either a healthy or diseased state under intrinsic urine pH. We demonstrated a systematic analysis of pH-dependent modulations on the human urine metabolite signals and further developed software for quantification of urine metabolite profiles with high accuracy, enabling the uncovering of potential metabolite biomarkers in clinical diagnosis applications.

The causal impact of body mass index on metabolic biomarkers and nonalcoholic fatty liver disease risk

BACKGROUND

Nonalcoholic fatty liver disease (NAFLD) is a growing global health concern linked to obesity.

METHODS

This study employed a Mendelian randomization approach to explore the causal influence of BMI on metabolic biomarkers and the subsequent risk of NAFLD. We analyzed data from multiple sources, including 249 metabolic traits, to establish direct and mediating relationships among BMI, metabolic factors, and NAFLD risk.

RESULTS

Our findings revealed a significant positive correlation between BMI and NAFLD across various datasets. We identified 176 metabolites associated with BMI, of which 106 were also linked to NAFLD. Importantly, 86 metabolites were found to mediate the relationship between BMI and NAFLD risk. Specifically, elevated levels of branched-chain amino acids, triglycerides, and certain cholesterol esters were notably associated with increased NAFLD risk, whereas changes in free cholesterol and phospholipid levels also played critical roles.

CONCLUSION

This study highlights the complex interactions between BMI, metabolic biomarkers, and NAFLD risk. By elucidating these relationships, we highlight potential targets for interventions aimed at reducing NAFLD incidence in populations with elevated BMI, ultimately contributing to improved metabolic health.

Metabolomic profiling reveals early biomarkers of gestational diabetes mellitus and associated hepatic steatosis

BACKGROUND

This study aims to identify early metabolomic biomarkers of gestational diabetes mellitus (GDM) and evaluate their association with hepatic steatosis.

METHODS

We compared maternal serum metabolomic profiles between women who developed GDM (n = 118) and matched controls (n = 118) during the first (10-14 gestational weeks) and second (24-28 gestational weeks) trimesters using ultra-performance liquid chromatography coupled with mass spectrometry. Mediation analysis was performed to evaluate the mediating role of metabolic dysfunction-associated steatotic liver disease (MASLD) in the relationship between metabolites and subsequent development of GDM. A refined prediction model was developed to predict GDM using established clinical factors and selected metabolites.

RESULTS

Significant alterations in circulating metabolites, including amino acids, bile acids, and phospholipids, were observed in the GDM group compared to controls during early pregnancy. Mediation analysis revealed that several metabolites, including glycocholic acid (proportion mediated (PM) = 31.9%), butanoyl carnitine (PM = 25.7%), and uric acid (PM = 22.4%), had significant indirect effects on GDM incidence mediated by hepatic steatosis. The refined prediction model composed of clinical factors and selected metabolites in the first trimester demonstrated higher performance in predicting GDM development than the established prediction model composed solely of clinical factors (AUC, 0.85 vs. 0.63, p < 0.001).

CONCLUSIONS

Women who developed GDM exhibited altered metabolomic profiles from early pregnancy, which showed a significant correlation with GDM, with MASLD as a mediator. Selected metabolomic biomarkers may serve as predictive markers and potential targets for early risk assessment and intervention in GDM.

RESEARCH INSIGHTS

WHAT IS CURRENTLY KNOWN ABOUT THIS TOPIC?: Gestational diabetes mellitus (GDM) is a common pregnancy complication with significant health risks. Early identification of women at high risk for GDM is crucial for timely intervention and improved outcomes. WHAT IS THE KEY RESEARCH QUESTION?: What alterations in circulating metabolites during early pregnancy are associated with subsequent GDM development? Does metabolic dysfunction-associated steatotic liver disease (MASLD) mediate the association between specific metabolites and GDM risk? WHAT IS NEW?: Significant alterations in bile acids, amino acids, phosphatidylethanolamines, and phosphatidylinositols were observed in early pregnancy sera of women who later developed GDM. MASLD significantly mediated the effects of several metabolites on GDM risk, with mediation proportions ranging from 9.7 to 31.9%. A refined prediction model composed of clinical factors and metabolites significantly improved the performance in predicting GDM development. HOW MIGHT THIS STUDY INFLUENCE CLINICAL PRACTICE?: These results provide new insights into early metabolic alterations associated with GDM development and highlight the potential mediating role of MASLD. This comprehensive metabolomic approach may contribute to the development of improved risk prediction models and targeted interventions for GDM prevention.

Amino Acid Hepatotoxicity Biomarkers in Human Hepatic Organoids: Promising Standardization of Drug Toxicity Evaluation

Human hepatic organoids (hHOs) are regarded as physiologically relevant in vitro platforms to evaluate hepatotoxicity, a critical step in drug development, but their applications are currently limited by the lack of qualified and standardized evaluation markers. In this study, by leveraging the established reference measurement system of amino acids (AAs), we propose 12 new biomarkers for drug-induced hepatotoxicity evaluation in human induced pluripotent stem cell-derived hHOs. Two orthogonal analytical methods for AAs were developed and validated based on isotope dilution mass spectrometry. Four AAs (aspartic acid, arginine, glutamine, and phenylalanine) and eight ratios of two designated AAs in the media of hHOs showed reliable alteration by drug treatment, which was confirmed by differentiating between hepatotoxic and nonhepatotoxic drugs. The superiorities of AA-based toxicity evaluation using the media of hHOs are as follows: (i) ability to use media only, without direct damage to or consumption of the organoids, (ii) ability to measure and compare quantities of AAs through a standardized reference measurement system rather than nonstandardized cell viability indicators, and (iii) no requirement for further data normalization in the case of the AA ratios. The AA analysis-based results demonstrate the reliability and potential of the proposed biomarkers as not only straightforward indicators of drug-induced hepatotoxicity but also absolutely comparable measures as a step toward standardization based on the AA reference measurement system.

Aqueous extract of Cornus officinalis alleviate NAFLD via protecting hepatocytes proliferation through regulation of the tricarboxylic acid cycle

ETHNOPHARMACOLOGICAL RELEVANCE

Cornus officinalis (CO) has been widely used as Chinese herbal medicine and has a good clinical efficacy in liver disease. In particular, it has a significant therapeutic effect on metabolic liver disease. However, systematic pharmacological studies on its hepatoprotective effect on non-alcoholic fatty liver disease (NAFLD) are lacking.

AIM OF THE STUDY

We investigated the impact of Cornus officinalis extract (COE) on two mouse models of NAFLD, screened the potential mechanisms of action by using metabolomics assays, and explored the protective effects on hepatocyte proliferation by regulating glutamate metabolism and tricarboxylic acid (TCA) cycle.

METHODS

The main components of COE were identified by high performance liquid chromatograph (HPLC). Male C57BL/6J mice were subjected to construct carbon tetrachloride (CCl4) or methionine choline deficient (MCD) induced NAFLD mice. Liver function and lipid biochemical indicators were detected using commercial assay kits. Masson staining, Western blot, and immunohistochemistry analyses were used for assessing hepatic injury and fibrosis. LC-MS non-targeted analysis was performed using the 1290 Ultra-High Performance Liquid Chromatograph System and the 6540 Q-TOF Mass Spectrometry. Palmitic acid (PA) induced L-02 cell model was established. The mediators in glutamate metabolism and TCA cycle were assessed by assay kits.

RESULTS

In vivo experiments validated that COE significantly improved liver function in NAFLD mice, reduced lipid accumulation, and alleviated pathological damage and liver fibrosis. The non-targeted metabolomics analysis combined with Ingenuity Pathway Analysis (IPA) located glutamate metabolism and the downstream TCA cycle as potential mechanisms of COE, which was further confirmed in NAFLD model mice and PA-induced L-02 cells. Finally, we confirmed that COE could promote mitochondrial energy supply by remodeling the homeostasis of the TCA cycle, thereby enhancing hepatocyte proliferation.

CONCLUSIONS

This study demonstrated that COE could significantly improve CCl4 or MCD-induced NAFLD by promoting hepatocyte proliferation. These results highlighted the potential of COE as leads for the development of innovative treatments for NAFLD.

Branched chain amino acid metabolism and microbiome in adolescents with obesity during weight loss therapy

BACKGROUND

Towards improving outcomes for adolescents with obesity, we aimed to define metabolic and microbiome phenotypes at baseline and post-weight loss intervention.

METHODS

The Pediatric Obesity Microbiome and Metabolism Study enrolled 220 adolescents aged 10-18 with severe obesity (OB) and 67 healthy weight controls (HWC). Blood, stool, and clinical measures were collected at baseline and after a 6-month intervention for the OB group. Serum metabolomic and fecal microbiome data were analyzed for associations with BMI, insulin resistance, and inflammation. Fecal microbiome transplants were performed on germ-free mice using samples from both groups to assess weight gain and metabolomic changes.

RESULTS

Adolescents with OB exhibited elevated serum branched-chain amino acids (BCAA) but reduced ketoacid metabolites (BCKA) compared to HWC. This pattern was sex- and age-dependent, unlike adults with OB, who showed elevated levels of both. The fecal microbiomes of adolescents with OB and HWC had similar diversity but differed in membership and functional potential. FMT from OB and HWC donors had similar effects on mouse body weight, with specific taxa linked to weight gain in FMT recipients. Longitudinal analysis identified metabolic and microbial features correlated with changes in health measures during the intervention.

CONCLUSION

Adolescents with OB have unique metabolomic adaptations and microbiome signatures compared to their HWC counterparts and adults with OB.

TRIAL REGISTRATION

ClinicalTrials.gov Identifier: NCT03139877 (Observational Study) and NCT02959034 (Repository).

FUNDING SOURCES

American Heart Association Grants: 17SFRN33670990, 20PRE35180195National Institute of Diabetes and Digestive and Kidney Diseases Grant: R24-DK110492.

Branched-chain amino acid metabolism: Pathophysiological mechanism and therapeutic intervention in metabolic diseases

Branched-chain amino acids (BCAAs), including leucine, isoleucine, and valine, are essential for maintaining physiological functions and metabolic homeostasis. However, chronic elevation of BCAAs causes metabolic diseases such as obesity, type 2 diabetes (T2D), and metabolic-associated fatty liver disease (MAFLD). Adipose tissue, skeletal muscle, and the liver are the three major metabolic tissues not only responsible for controlling glucose, lipid, and energy balance but also for maintaining BCAA homeostasis. Under obese and diabetic conditions, different pathogenic factors like pro-inflammatory cytokines, lipotoxicity, and reduction of adiponectin and peroxisome proliferator-activated receptors γ (PPARγ) disrupt BCAA metabolism, leading to excessive accumulation of BCAAs and their downstream metabolites in metabolic tissues and circulation. Mechanistically, BCAAs and/or their downstream metabolites, such as branched-chain ketoacids (BCKAs) and 3-hydroxyisobutyrate (3-HIB), impair insulin signaling, inhibit adipogenesis, induce inflammatory responses, and cause lipotoxicity in the metabolic tissues, resulting in multiple metabolic disorders. In this review, we summarize the latest studies on the metabolic regulation of BCAA homeostasis by the three major metabolic tissues-adipose tissue, skeletal muscle, and liver-and how dysregulated BCAA metabolism affects glucose, lipid, and energy balance in these active metabolic tissues. We also summarize therapeutic approaches to restore normal BCAA metabolism as a treatment for metabolic diseases.

Navigating liver health with metabolomics: A comprehensive review

Non-alcoholic fatty liver disease (NAFLD) is the main cause of chronic liver disease worldwide, affecting one-fourth of the world's population. With more than half of the world's population, the Asia-Pacific region contributed 62.6 % of liver-related fatal incidents in 2015. Currently, liver imaging techniques such as computed tomography (CT), nuclear magnetic resonance (NMR) spectroscopy, and ultrasound are non-invasive imaging methods to diagnose the disease. A liver biopsy is the gold standard test for establishing the definite diagnosis of non-alcoholic steatohepatitis (NASH). However, there are still significant problems with sample variability and the procedure's invasiveness. Numerous studies have indicated various non-invasive biomarkers for both fibrosis and steatosis to counter the invasiveness of diagnostic procedures. Metabolomics could be a promising method for detecting early liver diseases, investigating pathophysiology, and developing drugs. Metabolomics, when utilized with other omics technologies, can result in a deeper understanding of biological systems. Metabolomics has emerged as a prominent research topic, offering extensive opportunities to investigate biomarkers for liver diseases that are both sensitive and specific. In this review, we have described the recent studies involving the use of a metabolomics approach in the diagnosis of liver diseases, which would be beneficial for the early detection and treatment of liver diseases.

Metabolic Derangement in Non-Alcoholic Fatty Liver Disease: Opportunities for Early Diagnostic and Prognostic Markers

Non-alcoholic fatty liver disease is a globally prevalent disorder that can rapidly progress if not detected early. Currently, no accepted markers exist for early diagnosis and prognosis of NAFLD. This review describes derangement in major metabolic pathways of lipid, carbohydrate, and amino acids in NAFLD. It suggests that measuring levels of thrombospondin, TyG index, asymmetric dimethylarginine, LAL-A, GLP-1, FGF-21, and GSG index are potential markers for early diagnosis of NAFLD. A single marker may not indicate early NAFLD, and further large-scale studies on correlating levels of Thrombospondin-2, triglyceride-glucose index, and FGF-21 with NAFLD are warranted.

The Potential of Metabolomics as a Tool for Identifying Biomarkers Associated with Obesity and Its Complications: A Scoping Review

Obesity and its related diseases, such as type 2 diabetes (T2DM), cardiovascular disease (CVD), and metabolic fatty liver disease (MAFLD), require new diagnostic markers for earlier detection and intervention. The aim of this study is to demonstrate the potential of metabolomics as a tool for identifying biomarkers associated with obesity and its comorbidities in every age group. The presented systematic review makes an important contribution to the understanding of the potential of metabolomics in identifying biomarkers of obesity and its complications, especially considering the influence of branched-chain amino acids (BCAAs), amino acids (AAs) and adipokines on the development of T2DM, MAFLD, and CVD. The unique element of this study is the combination of research results from the last decade in different age groups and a wide demographic range. The review was based on the PubMed and Science Direct databases, and the inclusion criterion was English-language original studies conducted in humans between 2014 and 2024 and focusing on the influence of BCAAs, AAs or adipokines on the above-mentioned obesity complications. Based on the PRISMA protocol, a total of 21 papers were qualified for the review and then assigned to a specific disease entity. The collected data reveal that elevated levels of BCAAs and some AAs strongly correlate with insulin resistance, leading to T2DM, MAFLD, and CVD and often preceding conventional clinical markers. Valine and tyrosine emerge as potential markers of MAFLD progression, while BCAAs are primarily associated with insulin resistance in various demographic groups. Adipokines, although less studied, offer hope for elucidating the metabolic consequences of obesity. The review showed that in the case of CVDs, there is still a lack of studies in children and adolescents, who are increasingly affected by these diseases. Moreover, despite the knowledge that adipokines play an important role in the pathogenesis of obesity, there are no precise findings regarding the correlation between individual adipokines and T2DM, MAFLD, or CVD. In order to be able to introduce metabolites into the basic diagnostics of obesity-related diseases, it is necessary to develop panels of biochemical tests that will combine them with classical markers of selected diseases.

Comprehensive analysis of peripheral blood free amino acids in MASLD: the impact of glycine-serine-threonine metabolism

Little is known about how blood free amino acids (FAAs) change in metabolic dysfunction-associated steatotic liver disease (MASLD). This study aims to identify the imbalance of FAAs in MASLD and explore its correction as a potential therapeutic target. We analyzed plasma FAAs data from 23,036 individuals with steatosis information from a biobank in Japan, and 310 patients with MASLD were enrolled. According to diagnostic criteria for steatotic liver disease (SLD) or cardiometabolic criteria (CC), we divided the subjects into five groups: MASLD, metabolic dysfunction and alcohol-associated liver disease (MetALD), CC-SLD-, CC + SLD-, and CC-SLD + . Twenty FAAs were compared among these groups and among MASLD patients with pathological information. Among the 20 FAAs, the levels of 16 FAAs increased in CC + SLD- according to the number of matches with CC items associated with insulin resistance (IR). Steatosis enhanced most of these changes but serine (Ser) and threonine (Thr) were unaffected. Glycine (Gly), Ser and Thr were significantly decreased in patients according to steatosis grade. We investigated the association between these FAAs imbalances and pathogenesis using MASLD mouse models. In mice fed a high-fat, fructose, and cholesterol (FFC) diet, metabolomics and RNA sequencing analyses indicated that abnormality in Gly, Ser, and Thr metabolism in the liver was associated with mitochondrial dysfunction and enhanced glycolysis via pyruvate. High-Gly, Ser, and Thr diet ameliorated pathogenesis of MASLD in leptin-deficient mice. Most FAAs increase due to cardiometabolic abnormalities, particularly IR. However, interventions targeting the metabolism of Gly, Ser, and Thr have the potential to improve MASLD.

Metabolomics at the cutting edge of risk prediction of MASLD

Metabolic dysfunction-associated steatotic liver disease (MASLD) is a major public health threat globally. Management of patients afflicted with MASLD and research in this domain are limited by the lack of robust well-established non-invasive biomarkers for diagnosis, prognostication, and monitoring. The circulating metabolome reflects both the systemic metabo-inflammatory milieu and changes in the liver in affected individuals. In this review we summarize the available literature on changes in the different components of the metabolome in MASLD with a focus on changes that are linked to the presence of underlying steatohepatitis, severity of disease activity, and fibrosis stage. We further summarize the existing literature around biomarker panels that are derived from interrogation of the metabolome. Their relevance to disease biology and utility in practice are also discussed. We further highlight potential direction for future studies particularly to ensure they are fit for purpose and suitable for widespread use.

Essentiality of SLC7A11-mediated nonessential amino acids in MASLD

Metabolic dysfunction-associated steatotic liver disease (MASLD) remains a rapidly growing global health burden. Here, we report that the nonessential amino acid (NEAA) transporter SLC7A11 plays a key role in MASLD. In patients with MASLD, we found high expression levels of SLC7A11 that were correlated directly with clinical grade. Using both loss-of-function and gain-of-function genetic models, we found that Slc7a11 deficiency accelerated MASLD progression via classic cystine/cysteine deficiency-induced ferroptosis, while serine deficiency and a resulting impairment in de novo cysteine production were attributed to ferroptosis-induced MASLD progression in mice overexpressing hepatic Slc7a11. Consistent with these findings, we found that both serine supplementation and blocking ferroptosis significantly alleviated MASLD, and the serum serine/glutamate ratio was significantly lower in these preclinical disease models, suggesting that it might serve as a prognostic biomarker for MASLD in patients. These findings indicate that defects in NEAA metabolism are involved in the progression of MASLD and that serine deficiency-triggered ferroptosis may provide a therapeutic target for its treatment.

Interleukin 6 blockage alters the plasma metabolome in out-of-hospital cardiac arrest

BACKGROUND

Comatose patients resuscitated from out-of-hospital cardiac arrest (OHCA) exhibit a systemic inflammatory response, as indicated by elevated interleukin-6 (IL-6) levels, which is associated with increased mortality. Tocilizumab, an IL-6 receptor antagonist that reduced C-reactive protein response and markers of myocardial injury in a phase II OHCA trial.

AIM

To describe the early effects of tocilizumab on circulating levels of metabolites in comatose patients resuscitated from OHCA.

METHOD

Patients from the phase-II double-blinded randomized trial (NCT: 03863015) were included in this substudy. A total of 85 comatose patients resuscitated from OHCA were randomized at the time of arrival to the hospital to either tocilizumab 8 mg/kg or placebo, of which 80 received the intervention and did not later withdraw from the study. Plasma samples before randomization and 48 h later were analyzed by a targeted metabolomics approach quantifying 60 circulating metabolites.

RESULTS

Of 80 enrolled patients (median age 62 years (IQR: 54-72), men 66 (83 %)), 39 were randomized to tocilizumab group and 41 to placebo. Comorbidities and cardiac arrest characteristics were overall well-balanced. At hospital arrival, levels of metabolites from the tricarboxylic acid (TCA) cycle were associated with time to return of spontaneous circulation and independently with early levels of IL-6 (all p < 0.05). The early levels of medium-chain acylcarnitines were associated with age, NT-proBNP, estimated glomerular filtration rate, and marker of neurological injury (neurofilament light chain) (all p < 0.01). At 48 h, tocilizumab increased the levels of plasma amino acids, especially threonine, glycine, and serine, by more than a factor of 1.5 (p < 0.01). Two eicosanoids 15(S)-HETE and 12(S)-HETE were 1.9 times higher (p < 0.01).

CONCLUSION

Blocking the IL-6 receptor with tocilizumab early after OHCA impacts circulating metabolites, particularly those within the glycine, serine, and threonine pathways, highlighting the connection between acute systemic inflammation and metabolism. Further, early levels of TCA metabolites are independently associated with early inflammatory response and early medium-chain acylcarnitine with later markers of neurological injury.

Reductive stress-a common metabolic feature of obesity and cancer

Reductive stress, characterized by rising level of NADH (nicotinamide adenine dinucleotide) for a status of NADH/NAD+ ratio elevation, has been reported in obesity and cancer. However, the mechanism and significance of reductive stress remain to be established in obesity. This perspective is prepared to address the issue with new insights published recently. NADH is used in production of NADPH, glutathione, ATP and heat in the classical biochemistry. In obesity, elevation of NADH/NAD+ ratio, likely from overproduction due to substrate overloading, has been found in the liver for insulin resistance and gluconeogenesis. New evidence demonstrates that the elevation may induce lipogenesis, purine biosynthesis and gluconeogenesis through activation of transcription factors of ChREBP and NRF2. In cancer cells, NADH/NAD+ elevation under the Warburg effect is primarily derived from decreased NADH consumption in the mitochondrial respiration. Alternatively, NRF2 overactivation from gene mutation represents another mechanism of NADH/NAD+ elevation from NADH production in the cancer cells. The elevation is required for quick proliferation of cancer cells through induction of biosynthesis of the essential molecules. It appears that the causes of reductive stress are different between obesity and cancer, while its impact in anabolism is similar in the two conditions.

Distinct changes in serum metabolites and lipid species in the onset and progression of NAFLD in Obese Chinese

INTRODUCTION

Metabolic disturbances are major contributors to the onset and progression of non-alcoholic fatty liver disease (NAFLD), which includes a histological spectrum ranging from single steatosis (SS) to non-alcoholic steatohepatitis (NASH). This study aimed to identify serum metabolites and lipids enriched in different histological stages of NAFLD and to explore metabolites/lipids as non-invasive biomarkers in risk prediction of NAFLD and NASH in obese Chinese.

METHODS

Serum samples and liver biopsies were obtained from 250 NAFLD subjects. Untargeted metabolomic and lipidomic profiling were performed using Liquid Chromatography-Mass Spectrometry. Significantly altered metabolites and lipids were identified by MaAsLin2. Pathway enrichment was conducted with MetaboAnalyst and LIPEA. WGCNA was implemented to construct the co-expression network. Logistic regression models were developed to classify different histological stages of NAFLD.

RESULTS

A total of 263 metabolites and 550 lipid species were detected in serum samples. Differential analysis and pathway enrichment analysis revealed the progressive patterns in metabolic mechanisms during the transition from normal liver to SS and to NASH, including N-palmitoyltaurine, tridecylic acid, and branched-chain amino acid signaling pathways. The co-expression network showed a distinct correlation between different triglyceride and phosphatidylcholine species with disease severity. Multiple models classifying NAFLD versus normal liver and NASH versus SS identified important metabolic features associated with significant improvement in disease prediction compared to conventional clinical parameters.

CONCLUSION

Different histological stages of NAFLD are enriched with distinct sets of metabolites, lipids, and metabolic pathways. Integrated algorithms highlight the important metabolic and lipidomic features for diagnosis and staging of NAFLD in obese individuals.

Metabolic signatures of metabolic dysfunction-associated steatotic liver disease in severely obese patients

BACKROUND

Metabolic dysfunction-associated steatotic liver disease (MASLD) can lead to liver fibrosis, cirrhosis, and hepatocellular carcinoma. Still, most patients with MASLD die from cardiovascular diseases indicating metabolic alterations related to both liver and cardiovascular pathology.

AIMS AND METHODS

The aim of this study was to assess biologic pathways behind MASLD progression from steatosis to metabolic dysfunction-associated steatohepatitis (MASH) using non-targeted liquid chromatography-mass spectrometry analysis in 106 severely obese individuals (78 women, mean age 47.7 7 ± 9.2 years, body mass index 41.8 ± 4.3 kg/m²) undergoing laparoscopic Roux-en-Y gastric bypass.

RESULTS

We identified several metabolites that are associated with MASLD progression. Most importantly, we observed a decrease of lysophosphatidylcholines LPC(18:2), LPC(18:3), and LPC(20:3) and increase of xanthine when comparing those with steatosis to those with MASH. We found that indole propionic acid and threonine were negatively correlated to fibrosis, but not with the metabolic disturbances associated with cardiovascular risk. Xanthine, ketoleucine, and tryptophan were positively correlated to lobular inflammation and ballooning but also with insulin resistance, and dyslipidemia, respectively. The results did not change when taking into account the most important genetic risk factors of MASLD.

CONCLUSIONS

Our findings suggest that there are several separate biological pathways, some of them independent of insulin resistance and dyslipidemia, associating with MASLD.

Comparable glucagon-stimulated amino acid suppression in individuals with and without hepatic steatosis or steatohepatitis

Hepatic amino acid (AA) metabolism and glucagon secretion are linked in a feedback cycle in which circulating AAs stimulate glucagon secretion and alpha-cell proliferation, whereas glucagon stimulates hepatic AA catabolism. It has been proposed that metabolic dysfunction-associated steatotic liver disease (MASLD) leads to hepatic glucagon resistance, which may result in hyperaminoacidemia and hyperglucagonemia. We tested the glucagon effect on AA metabolism in subjects with obesity; 11 with steatohepatitis (MASH), 10 with steatosis (MAS), and 7 subjects [control (CON)] without steatosis. We performed a somatostatin clamp with infusions of insulin and low dose followed by high-dose glucagon. We measured plasma levels of 17 AAs and assessed hepatic fat content (FF%) and body fat distribution (visceral and subcutaneous adipose tissue mass) by MRI. HighGlucagon suppressed plasma total AA equally in all groups; MASH 13% (SD 9%), MAS 14% (7%), and CON 11% (5%), respectively. In univariate regression analyses, visceral adipose tissue mass (β = 0.471, P = 0.011) and AA concentration at LowGlucagon (β = -0.524, P = 0.004), but not FF% (β = -0.243, P = 0.213), were significant predictors of AA reduction. Using a stepwise backward multiple regression approach revealed similar results. Total and specific AA levels (glutamic acid and tyrosine) were higher in both MASLD groups during the study, and FF% was positively correlated to a number of individual AAs. Although finding elevated AA concentrations in subjects with MASLD, we conclude that in patients with MASLD that do not have elevated glucagon at baseline, glucagon suppresses circulating AA levels equally in subjects with and without MASLD. ClinicalTrials.gov: NCT04042142.NEW & NOTEWORTHY The purpose of the study was to investigate the concept of "glucagon resistance" in metabolic dysfunction-associated steatotic liver disease (MASLD) pathogenesis. We asked if a disruption of the glucagon-mediated suppression of hepatic amino acid (AA) catabolism is present in individuals with MASLD compared with individuals with obesity but no MASLD. Contrary to expectations, we found no disruption of the glucagon-stimulated suppression of plasma AA concentration, which disputes the hypothesis that MASLD causes resistance to glucagon.

Coriandrum sativum L. Leaf Extract Ameliorates Metabolic Dysfunction-Associated Steatotic Liver Disease by Modulating the AMPK Pathway in High Fat-Fed C57BL/6 Mice

BACKGROUND

Nonalcoholic fatty liver disease (NAFLD) is the most common chronic liver disease. In recent times, the term NAFLD has been modified to metabolic dysfunction-associated steatotic liver disease (MASLD), reflecting its comprehensive scope encompassing a range of metabolic abnormalities. Coriandrum sativum L. (CS) is a traditional medicine, although the preventive mechanism of CS extracts remains unclear.

OBJECTIVE

This study evaluated the preventive effects of CS in high-fat diet (HFD)-induced MASLD mice by oral administration of 100 or 200 mg/kg/day of CS extracts for 12 weeks.

RESULTS

The major CS extract compounds were chlorogenic acid, caffeic acid, rutin, and isoquercetin. The administration of CS extract suppressed HFD-induced weight gain, liver weight, and the liver/body weight ratio. It improved the mice's serum biological profiles and suppressed HFD-induced lipid droplet and lipid accumulation by inhibiting lipid accumulation-related gene expression in the liver. It modulated HFD-induced Ampk-Srebp1c pathways and suppressed HFD-induced NF-κB pathway activation in the liver. It regulated inflammation and the AMPK alpha signaling pathway in HFD-fed mice by reducing the accumulation of specific amino acids, leading to the amelioration of fatty liver.

CONCLUSIONS

The CS extract prevents HFD-induced MASLD and may help prevent or treat MASLD.

Even moderate liver fat accumulation below conventional fatty liver cutoffs is linked to multiple metabolomic alterations and gestational dysglycemia in Asian women of reproductive age

BACKGROUND

It is not clear if conventional liver fat cutoff of 5.56% weight which has been used for identifying fatty liver in western populations is also applicable for Asians. In Asian women of reproductive age, we evaluate the optimum metabolic syndrome (MetS)-linked liver fat cutoff, the specific metabolomic alterations apparent at this cutoff, as well as prospective associations of preconception liver fat levels with gestational dysglycemia.

METHODS

Liver fat (measured by magnetic resonance spectroscopy), MetS, and nuclear magnetic resonance (NMR)-based plasma metabolomic profiles were assessed in 382 Asian women, who were planning to conceive. Ninety-eight women went on to become pregnant and received an oral glucose tolerance test at week 26 of gestation.

RESULTS

The optimum liver fat cutoff for diagnosing MetS was 2.07%weight. Preconception liver fat was categorized into Low (liver fat < 2.07%), Moderate (2.07% ≤ liver fat < 5.56%), and High (liver fat ≥ 5.56%) groups. Individual MetS traits showed worsening trends, going from Low to Moderate to High groups. Multiple plasma metabolomic alterations, previously linked to incident type 2 diabetes (T2D), were already evident in the Moderate group (adjusted for ethnicity, age, parity, educational attainment, and BMI). Both a cross-sectional multi-metabolite score for incident T2D and mid-gestational glucose area under the curve showed increasing trends, going from Low to Moderate to High groups (p < 0.001 for both). Gestational diabetes incidence was 2-fold (p = 0.23) and 7-fold (p < 0.001) higher in the Moderate and High groups relative to the Low group.

CONCLUSIONS

In Asian women of reproductive age, moderate liver fat accumulation below the conventional fatty liver cutoff was not metabolically benign and was linked to gestational dysglycemia. The newly derived cutoff can aid in screening individuals before adverse metabolic phenotypes have consolidated, which provides a longer window for preventive strategies.

TAT as a new marker and its use for noninvasive chemical biopsy in NASH diagnosis

BACKGROUND

Early diagnosis of Nonalcoholic steatohepatitis (NASH) is crucial to prevent its progression to hepatocellular carcinoma, but its gold standard diagnosis still requires invasive biopsy. Here, a new marker-based noninvasive chemical biopsy approach is introduced that uses urine-secreted tyrosine metabolites.

METHODS

We first identified NASH-specific decrease in TAT expression, the first enzyme in the tyrosine degradation pathway (TDP), by employing exometabolome-transcriptome correlations, single-cell RNA -seq, and tissue staining on human NASH patient samples. A selective extrahepatic monitoring of the TAT activity was established by the chemical biopsy exploiting the enzyme's metabolic conversion of D2-tyrosine into D2-4HPP. The approach was applied to a NASH mouse model using the methionine-choline deficient diet, where urine D2-4HPP level was measured with a specific LC-MS detection, following oral administration of D2-tyrosine.

RESULTS

The noninvasive urine chemical biopsy approach could effectively differentiate NASH from normal mice (normal = 14, NASH = 15, p = 0.0054), correlated with the NASH pathology and TAT level decrease observed with immunostaining on the liver tissue. In addition, we showed that the diagnostic differentiation could be enhanced by measuring the downstream metabolites of TDP. The specificity of the TAT and the related TDP enzymes in NASH were also addressed in other settings employing high fat high fructose mouse NASH model and human obesity vs. NASH cohort.

CONCLUSIONS

Overall, we propose TAT and TDP as pathology-relevant markers for NASH and present the urine chemical biopsy as a noninvasive modality to evaluate the NASH-specific changes in urine that may help the NASH diagnosis.

Altered amino acid levels in young hypopituitarism: impact of NAFLD and insulin resistance

Elevated concentrations of amino acids (AAs) are commonly observed in patients with nonalcoholic fatty liver disease (NAFLD). Individuals with hypopituitarism (HP) are at a heightened risk of developing NAFLD due to factors such as visceral obesity, increased insulin resistance (IR), and disturbances in lipid metabolism. However, the changes in AAs concentrations associated with HP remain poorly understood. Therefore, our study aimed to investigate whether individuals with HP, who were not receiving growth hormone replacement therapy (GHRT), exhibited altered AAs compared to controls (CTs), and whether these AAs were associated with IR, the presence of NAFLD, and the Metabolic Syndrome (MetS) score. The AAs profiles of 133 young males with HP (age: 24.5 ± 5.9; 57 with NAFLD and 76 without NAFLD) and 90 age and BMI-matched CTs were analyzed using untargeted metabolomics. The results revealed that most AAs were found to be elevated in subjects with HPs compared to CTs. Glutamate, glutamine, norleucine, and branched-chain amino acids (BCAAs) (leucine and valine) were correlated with the homeostasis model assessment of insulin resistance (HOMA-IR), with glutamate and norleucine showing independent linkage. Glutamate and proline levels were specifically associated with MetS score, while alanine and proline linked to NAFLD. Given that elevated glutamate and BCAAs levels have higher prevalence of NAFLD, we hypothesized that the changes in AAs observed in HPs may be attributed to the impact of NAFLD and IR.

Oxyntomodulin physiology and its therapeutic development in obesity and associated complications

Incretins, such as glucagon-like peptide-1 (GLP1) and glucose-dependent insulinotropic polypeptide (GIP), have advanced the treatment landscape of obesity to a new pinnacle. As opposed to singular incretin effects, oxyntomodulin (OXM) activates glucagon receptors (GCGR) and glucagon-like peptide-1 receptors (GLP1R), demonstrating a more dynamic range of effects that are more likely to align with evolving 'health gains' goals in obesity care. Here, we will review the molecular insights from their inception to recent developments and challenges. This review will discuss the physiological actions of OXM, primarily appetite regulation, energy expenditure, and glucose homeostasis. Finally, we will shed light on the development of OXM-based therapies for obesity and associated complications, and outline important considerations for more translational efforts.

Branched-chain amino acids alleviate NAFLD via inhibiting de novo lipogenesis and activating fatty acid β-oxidation in laying hens

The adverse metabolic impacts of branched-chain amino acids (BCAA) have been elucidated are mediated by isoleucine and valine. Dietary restriction of isoleucine promotes metabolic health and increases lifespan. However, a high protein diet enriched in BCAA is presently the most useful therapeutic strategy for nonalcoholic fatty liver disease (NAFLD), yet, its underlying mechanism remains largely unknown. Fatty liver hemorrhagic syndrome (FLHS), a specialized laying hen NAFLD model, can spontaneously develop fatty liver and hepatic steatosis under a high-energy and high-protein dietary background that the pathogenesis of FLHS is similar to human NAFLD. The mechanism underlying dietary BCAA control of NAFLD development in laying hens remains unclear. Herein, we demonstrate that dietary supplementation with 67 % High BCAA has unique mitigative impacts on NAFLD in laying hens. A High BCAA diet alleviates NAFLD, by inhibiting the tryptophan-ILA-AHR axis and MAPK9-mediated de novo lipogenesis (DNL), promoting ketogenesis and energy metabolism, and activating PPAR-RXR and pexophagy to promote fatty acid β-oxidation. Furthermore, we uncover that High BCAA strongly activates ubiquitin-proteasome autophagy via downregulating UFMylation to trigger MAPK9-mediated DNL, fatty acid elongation and lipid droplet formation-related proteins ubiquitination degradation, activating PPAR-RXR and pexophagy mediated fatty acid β-oxidation and lipolysis. Together, our data highlight moderating intake of high BCAA by inhibiting the AHR/MAPK9 are promising new strategies in NAFLD and FLHS treatment.

Mechanistic role of long non-coding RNAs in the pathogenesis of metabolic dysfunction-associated steatotic liver disease and fibrosis

Metabolic dysfunction-associated steatotic liver disease (MASLD), previously referred to as non-alcoholic fatty liver disease, encompasses a broad range of hepatic metabolic disorders primarily characterised by the disruption of hepatic lipid metabolism, hepatic lipid accumulation and steatosis. Severe cases of MASLD might progress to metabolic dysfunction-associated steatohepatitis, characterised by hepatic inflammation, hepatocyte ballooning degeneration, activation of hepatic stellate cells (HSCs) and fibrogenesis. It may further progress to hepatocellular carcinoma. In the liver, long non-coding RNAs (lncRNAs) target multiple metabolic pathways in hepatocytes, HSCs, and Kupffer cells at different stages of MASLD and liver fibrosis. In this study, we overview recent findings on the potential role of lncRNAs in the pathogenesis of MASLD and liver fibrosis via modulation of de novo lipid synthesis, fatty acid β-oxidation, lipotoxicity, oxidative stress, metabolic inflammation, mammalian target of rapamycin signalling, apoptosis, ubiquitination and fibrogenesis. We critically assess the literature reports that investigate the complex interplay between lncRNA, microRNA and key mediators in liver injury, in both human participants and animal models of MASLD and liver fibrosis. We also highlight the therapeutic potential of lncRNAs in chronic liver diseases.

The influence of glutamate receptors on insulin release and diabetic neuropathy

Diabetes causes macrovascular and microvascular complications such as peripheral neuropathy. Glutamate regulates insulin secretion in pancreatic β-cells, and its increased activity in the central nervous system is associated with peripheral neuropathy in animal models of diabetes. One strategy to modulate glutamatergic activity consists in the pharmacological manipulation of metabotropic glutamate receptors (mGluRs), which, compared to the ionotropic receptors, allow for a fine-tuning of neurotransmission that is compatible with therapeutic interventions. mGluRs are a family of eight G-protein coupled receptors classified into three groups (I-III) based on sequence homology, transduction mechanisms, and pharmacology. Activation of group II and III or inhibition of group I represents a strategy to counteract the glutamatergic hyperactivity associated with diabetic neuropathy. In this review article, we will discuss the role of glutamate receptors in the release of insulin and the development/treatment of diabetic neuropathy, with particular emphasis on their manipulation to prevent the glutamatergic hyperactivity associated with diabetic neuropathy.

MASLD in persons with HIV is associated with high cardiometabolic risk as evidenced by altered advanced lipoprotein profiles and targeted metabolomics

BACKGROUND

Metabolic dysfunction associated steatotic liver disease (MASLD) is associated with increased cardiovascular disease (CVD) risk in persons with HIV (PWH). The lipidomic and metabolomic alterations contributing to this risk are poorly understood. We aimed to characterize the advanced lipoprotein and targeted metabolomic profiles in PWH and assess if the presence and severity of MASLD influence these profiles.

METHODS

This is a cross-sectional analysis of a prospectively enrolled multicenter cohort. PWH without alcohol abuse or known liver disease underwent vibration-controlled transient elastography for controlled attenuation parameter (CAP) and liver stiffness measurement (LSM). Lipidomic and metabolomic profiling was undertaken with nuclear magnetic resonance (NMR) spectroscopy. Hepatic steatosis was defined as CAP ≥ 263 dB/m and clinically significant fibrosis (CSF) as LSM ≥ 8 kPa. Logistic regression models assessed associations between MASLD, CSF and lipidomic and metabolic parameters.

RESULTS

Of 190 participants (71% cisgender male, 96% on antiretroviral therapy), 58% had MASLD and 12% CSF. Mean (SD) age was 48.9 (12.1) years and body mass index (BMI) 29.9 (6.4) kg/m2. Compared to PWH without MASLD (controls), PWH with MASLD had lower HDL-C but higher total triglyceride, VLDL-C, branched-chain amino acids, GlycA, trimethylamine N-oxide levels, Lipoprotein-Insulin Resistance and Diabetes Risk Indices. There were no significant differences in these parameters between participants with MASLD with or without CSF. In a multivariable regression analysis, MASLD was independently associated with changes in most of these parameters after adjustment for age, gender, race/ethnicity, type 2 diabetes mellitus, BMI, and lipid lowering medications use.

CONCLUSIONS

MASLD in PWH is independently associated with altered advanced lipoprotein and targeted metabolic profiles, indicating a higher CVD risk in this population.

Glucagon, Metabolic Dysfunction-Associated Steatotic Liver Disease and Amino Acids in Humans and Animals without Diabetes Mellitus-An Evidence Map

INTRODUCTION

Health systems are confronted with not only the growing worldwide childhood obesity epidemic but also associated comorbidities. These subsequently cause variations in distinct metabolic pathways, leading to metabolic dysfunction-associated steatotic liver disease (MASLD). The aim of this evidence map is to systematically evaluate the evidence and to identify research gaps on glucagon-induced amino acid (AA) turnover and its metabolic interaction with MASLD.

METHODOLOGY

A systematic literature search was conducted up to April 2023 in three electronic databases. Studies were required to include at least two of the main research areas, glucagon, AA metabolism and MASLD. Two independent reviewers screened titles and abstracts according to prespecified eligibility criteria, as well as full-text articles. Results are summarized in tables stratified by human and animal studies and study population age.

RESULTS

Thirty-four references were ultimately included. The publication years dated back to 1965 showed a great increase from 2012 to 2023. In total, there were 19 animal studies and 15 human studies. Among the human studies, except for two studies in adolescents, all the studies were conducted in adults. In human studies, the methods used to evaluate metabolic changes differed among hyperinsulinemic-euglycemic clamp and oral glucose tolerance tests. Thirteen studies focused on the metabolic effects of MASLD, while only two studies explored the interaction between MASLD, glucagon and AA metabolism in humans. The other 19 studies focused on metabolomics, beta cell function or just one topic of a research area and not on interactions between one another.

CONCLUSION

Research on the interaction between MASLD, glucagon and AA metabolism in humans is sparse and complete lacking in pediatrics. Furthermore, longitudinal studies with a focus on hyperglucagonemia independent of diabetes but related to MASLD present an unambiguous research gap.

Propylthiouracil Induced Rat Model Reflects Heterogeneity Observed in Clinically Non-Obese Subjects with Nonalcoholic Fatty Liver Disease

The prevalence of nonalcoholic fatty liver disease (NAFLD) is increasing, affecting up to 30% of the population, with approximately 20% of cases occurring in non-obese individuals. The recent shift to the term metabolic dysfunction-associated steatosis liver disease (MASLD) highlights the disease's heterogeneity. However, there are no well-established animal models replicating non-obese NAFLD (NO-NAFLD). This study aimed to evaluate the relevance of the high-fat diet (HFD) combined with the propylthiouracil (PTU)-induced rat model in mimicking the histopathology and pathophysiology of NO-NAFLD. We first analyzed metabolic and clinical parameters between NO-NAFLD patients (Average BMI = 21.96 kg/m2) and obese NAFLD patients (Average BMI = 29.7 kg/m2). NO-NAFLD patients exhibited significantly higher levels of carnitines, phospholipids, and triglycerides. In the animal model, we examined serum lipid profiles, liver inflammation, histology, and transcriptomics. Hepatic steatosis in the HFD+PTU model at week 4 was comparable to that of the HFD model at week 8. The HFD+PTU model showed higher levels of carnitines, phospholipids, and triglycerides, supporting its relevance for NO-NAFLD. Additionally, the downregulation of lipid synthesis-related genes indicated differences in lipid accumulation between the two models. Overall, the HFD+PTU-induced rat model is a promising tool for studying the molecular mechanisms of NO-NAFLD.

Inhibition of hepatic oxalate overproduction ameliorates metabolic dysfunction-associated steatohepatitis

The incidence of metabolic dysfunction-associated steatohepatitis (MASH) is on the rise, and with limited pharmacological therapy available, identification of new metabolic targets is urgently needed. Oxalate is a terminal metabolite produced from glyoxylate by hepatic lactate dehydrogenase (LDHA). The liver-specific alanine-glyoxylate aminotransferase (AGXT) detoxifies glyoxylate, preventing oxalate accumulation. Here we show that AGXT is suppressed and LDHA is activated in livers from patients and mice with MASH, leading to oxalate overproduction. In turn, oxalate promotes steatosis in hepatocytes by inhibiting peroxisome proliferator-activated receptor-α (PPARα) transcription and fatty acid β-oxidation and induces monocyte chemotaxis via C-C motif chemokine ligand 2. In male mice with diet-induced MASH, targeting oxalate overproduction through hepatocyte-specific AGXT overexpression or pharmacological inhibition of LDHA potently lowers steatohepatitis and fibrosis by inducing PPARα-driven fatty acid β-oxidation and suppressing monocyte chemotaxis, nuclear factor-κB and transforming growth factor-β targets. These findings highlight hepatic oxalate overproduction as a target for the treatment of MASH.

Altered biliary microbial and metabolic profile reveals the crosstalk between NAFLD and cholelithiasis

BACKGROUND

The relationship between non-alcoholic fatty liver disease (NAFLD) and cholelithiasis is intricate, with alterations in the microenvironment potentially mediating this interplay. Thus, this study aimed to explore the biliary microbiota and metabolites of patients with cholelithiasis and detect changes induced by comorbid NAFLD.

METHODS

In this study, 16S rRNA gene sequencing and metabolome analysis were performed on biliary samples collected from 35 subjects. Then, patients were stratified into two groups: the comorbidity group (n = 18), consisting of cholelithiasis patients with NAFLD, and the non-comorbidity group (n = 17), comprising cholelithiasis patients without NAFLD.

RESULTS

Comorbid NAFLD did not significantly increase α-diversity but affected β-diversity. A statistically significant difference was observed in the abundance of biliary metabolites between the two groups. Specifically, differences in the abundance of 4 phyla, 19 genera, and 28 metabolites were significant between the two groups. Correlation analysis demonstrated positive associations among 12α-hydroxylated bile acid levels, Pyramidobacter and Fusobacterium abundance, AST levels, and the fibrosis-4 index (p < 0.05, r > 0.3), all of which were increased in patients with cholelithiasis and comorbid NAFLD.

CONCLUSIONS

The relationship between cholelithiasis and NAFLD influences the biliary microbial and metabolic profile, creating a detrimental microenvironment that promotes the disease progression.

Hepatic estrogen receptor alpha drives masculinization in post-menopausal women with metabolic dysfunction-associated steatotic liver disease

Background & Aims

The loss of ovarian functions defining menopause leads to profound metabolic changes and heightens the risk of developing metabolic dysfunction-associated steatotic liver disease (MASLD). Although estrogens primarily act on the female liver through estrogen receptor alpha (ERα), the specific contribution of impaired ERα signaling in triggering MASLD after menopause remains unclear.

Methods

To address this gap in knowledge, we compared the liver transcriptomes of sham-operated (SHAM) and ovariectomized (OVX) control and liver ERα knockout (LERKO) female mice by performing RNA-Seq analysis.

Results

OVX led to 1426 differentially expressed genes (DEGs) in the liver of control mice compared to 245 DEGs in LERKO mice. Gene ontology analysis revealed a distinct ovariectomy-induced modulation of the liver transcriptome in LERKO compared with controls, indicating that hepatic ERα is functional and necessary for the complete reprogramming of liver metabolism in response to estrogen depletion. Additionally, we observed an ovariectomy-dependent induction of male-biased genes, especially in the liver of control females, pointing to hepatic ERα involvement in the masculinization of the liver after estrogen loss. To investigate the translational relevance of such findings, we assessed liver samples from a cohort of 60 severely obese individuals (51 women; 9 men). Notably, a shift of the liver transcriptome toward a male-like profile was also observed only in obese women with MASLD (n = 43), especially in women ≥51 years old (15/15), suggesting that masculinization of the female liver contributes to MASLD development in obese women.

Conclusions

These results highlight the role of hepatic ERα in driving masculinization of the liver transcriptome following menopause, pointing to this receptor as a potential pharmacological target for preventing MASLD in post-menopausal women.

Impact and implications

Despite the increased risk of developing MASLD after menopause, the specific contribution of impaired hepatic estrogen signaling in driving MASLD in females has not been a major research focus, and, thus, has limited the development of tailored strategies that address the specific mechanisms underlying MASLD in post-menopausal women. This study reveals the functional role of hepatic ERα in mediating liver metabolic changes in response to estrogens loss, leading to a shift in the liver transcriptome towards a male-like profile. In women with obesity, this shift is associated with the development of MASLD. These findings underscore the potential of targeting hepatic ERα as a promising approach for developing effective, sex-specific treatments to preserve liver health and prevent or limit the development and progression of MASLD in post-menopausal women.

Hepatic steatosis and not type 2 diabetes, body mass index, or hepatic fibrosis associates with hyperglucagonemia in individuals with steatotic liver disease

Increased plasma concentrations of glucagon (hyperglucagonemia) are reported in patients with type 2 diabetes (T2D) and are considered a diabetogenic risk factor. Emerging evidence suggests that hepatic steatosis in obesity is causing a condition of resistance toward glucagon's effects on amino acid metabolism, resulting in an amino acid-induced hyperglucagonemia. We investigated the presence of hyperglucagonemia in individuals with biopsy-verified metabolic dysfunction-associated steatotic liver disease (MASLD), and whether body mass index (BMI), T2D, hepatic steatosis, and/or fibrosis contribute to this relationship. To dissect potential mechanisms, we also determined hepatic gene expression related to amino acid transport and catabolism. Individuals with MASLD had hyperglucagonemia {controls (n = 74) vs. MASLD (n = 106); median [Q1, Q3]; 4 [3, 7] vs. 8 [6, 13] pM), P < 0.0001} and were glucagon resistant (assessed by the glucagon-alanine index) {1.3 [0.9, 2.1] vs. 3.3 [2.1, 5.3] pM·mM, P < 0.0001}. These changes were associated with hepatic steatosis (P < 0.001, R2 > 0.25) independently of BMI, sex, age, and T2D. Plasma levels of glucagon were similar in individuals with MASLD when stratified on T2D status {MASLD-T2D (n = 52) vs. MASLD + T2D (n = 54); 8 [6, 11] vs. 8 [6, 13] pM, P = 0.34} and hepatic fibrosis {MASLD + F0 (n = 25) vs. MASLD + F1-F3 (n = 67); 8.4 [7.0, 13.3] vs. 7.9 [5.2, 11.6] pM, P = 0.43}. Obesity (BMI = 30 kg/m2) did not alter glucagon levels (P = 0.65) within groups (control/MASLD). The mRNA expression of proteins involved in amino acid transport and catabolism was downregulated in MASLD. Thus, relative hyperglucagonemia is present in individuals with biopsy-verified MASLD, and hepatic steatosis partially drives hyperglucagonemia and glucagon resistance, irrespective of T2D, BMI, and hepatic fibrosis.NEW & NOTEWORTHY Individuals with metabolic dysfunction-associated steatotic liver disease (MASLD) present with increased plasma levels of glucagon (hyperglucagonemia), irrespective of body mass index (BMI) and type 2 diabetes. Therefore, MASLD and the resultant hyperglucagonemia may act as a diabetogenic risk factor. Notably, hepatic steatosis was a significant contributor to the hyperglucagonemia in MASLD, potentially unveiling a pathway for the hyperglucagonemia in some patients with type 2 diabetes.

Investigating the efficacy of acupuncture in treating patients with metabolic-associated fatty liver disease: a protocol for a randomised controlled clinical trial

INTRODUCTION

Acupuncture is widely used for metabolic-associated fatty liver disease (MAFLD) treatment; however, the clinical efficacy has not been confirmed due to the lack of high-level evidence-based clinical practice. The purpose of this study is to design a research protocol that will be used to determine the efficacy of acupuncture versus sham acupuncture (SHA) for MAFLD treatment.

METHODS AND ANALYSIS

This will be a multicentre, randomised and sham-controlled trial. Ninety-eight participants with MAFLD will be enrolled in this trial. Participants will be randomly assigned in a 1:1 ratio to receive acupuncture or SHA for 12 weeks. The primary outcome is the rate of patients with a 30% relative decline in liver fat after 12 weeks of treatment in MRI-proton density fat fraction (MRI-PDFF), which will be obtained by quantitative chemical shift imaging such as the multipoint Dixon method at 0, 12 and 24 weeks. Secondary outcomes include the changes in the relative liver fat content measured by MRI-PDFF, magnetic resonance elastography, liver function, lipid metabolism, homeostatic model assessment for insulin resistance (HOMA-IR) and serum high sensitivity C reactive protein, which will be obtained at 0, 6, 12 and 24 weeks. Body measurement indicators (body mass index, waist circumference, hip circumference and waist-to-hip ratio) will be obtained at 0, 3, 6, 9, 12 and 24 weeks. The alteration in the gut microbiota composition and its metabolism will be assessed by 16S ribosomal RNA sequencing and liquid chromatography-mass spectrometry at 0 and 12 weeks.

ETHICS AND DISSEMINATION

This study protocol has been approved by the ethics committee of Shuguang Hospital Affiliated to Shanghai University of Traditional Chinese Medicine (2023-1347-114-01). The results of this study will be published in a peer-reviewed journal and presented at academic conferences.

TRIAL REGISTRATION NUMBER

ChiCTR2300075701.

Plasma Circulating Metabolites Associated With Steatotic Liver Disease and Liver Enzymes: A Multiplatform Population-Based Study

Background and Aims

Steatotic liver disease (SLD) is the most common chronic liver disease strongly associated with metabolic dysfunction, but its pathogenesis remains incompletely understood. Exploring plasma circulating metabolites may help in elucidating underlying mechanisms and identifying new biomarkers for SLD.

Methods

We examined cross-sectionally the association between plasma metabolites and SLD as well as liver enzymes using data from 4 population-based cohort studies (Rotterdam study, Avon Longitudinal Study of Parents and Children, The Insulin Resistance Atherosclerosis Family Study, and Study of Latinos). Metabolites were assessed in the Nightingale platform (n = 225 metabolites) by nuclear magnetic resonance spectroscopy and in the Metabolon platform (n = 991 metabolites) by ultra-high-performance liquid chromatography-mass spectrometry. Serum levels of liver enzymes (alanine aminotransferase, aspartate aminotransferase, and gamma-glutamyl transpeptidase) were measured and SLD was diagnosed by ultrasound or computed tomography scan. Logistic and linear regression models were performed per cohort and meta-analyzed. A false discovery rate < 0.05 was considered as significant threshold.

Results

Several metabolites were significantly associated with SLD and liver enzymes, of which 21 metabolites were associated with both traits. The most significant associations were observed with phenylalanine, triglycerides in (high-density lipoprotein, intermediate-density lipoprotein, and small low-density lipoprotein), fatty acid (FA) ratios of (18:2 linoleic acid-to-total FA, omega 6 FA-to-total FA, and polyunsaturated FA-to-total FA) from the Nightingale and glutamate and sphingomyelin from the Metabolon platform. Other associated metabolites were mainly involved in lipid, amino acid, carbohydrates, and peptide metabolism.

Conclusion

Our study indicates a landscape of circulating metabolites associated with SLD. The identified metabolites may contribute to a better understanding of the metabolic pathways underlying SLD and hold promising for potential biomarkers in early diagnosis and monitoring of the disease.

Deciphering the Gut–Liver Axis: A Comprehensive Scientific Review of Non-Alcoholic Fatty Liver Disease

Non-alcoholic fatty liver disease (NAFLD) has emerged as a significant global health issue. The condition is closely linked to metabolic dysfunctions such as obesity and type 2 diabetes. The gut–liver axis, a bidirectional communication pathway between the liver and the gut, plays a crucial role in the pathogenesis of NAFLD. This review delves into the mechanisms underlying the gut–liver axis, exploring the influence of gut microbiota, intestinal permeability, and inflammatory pathways. This review also explores the potential therapeutic strategies centered on modulating gut microbiota such as fecal microbiota transplantation; phage therapy; and the use of specific probiotics, prebiotics, and postbiotics in managing NAFLD. By understanding these interactions, we can better comprehend the development and advancement of NAFLD and identify potential therapeutic targets.

Estrogen alleviates liver fibrosis and restores metabolic homeostasis in ovariectomy-induced liver injury and carbon tetrachloride (CCl4) exposure

AIM

Given estrogen's recognized regulatory influence on diverse metabolic and immune functions, this study sought to explore its potential impact on fibrosis and elucidate the underlying metabolic regulations.

METHODS

Female mice underwent ovary removal surgery, followed by carbon tetrachloride (CCl4) administration to induce liver injury. Biochemical index analysis and histopathological examination were then conducted. The expression levels of alpha-smooth muscle actin (α-SMA), transforming growth factor-β (TGF-β), and collagen type 1 alpha 1 chain (COL1A1) were assessed using western blotting to further elucidate the extent of liver injury. Finally, metabolite extraction and metabolomic analysis were performed to evaluate metabolic changes.

RESULTS

Ovary removal exacerbated CCl4-induced liver damage, while estrogen supplementation provided protection against hepatic changes resulting from OVX. Furthermore, estrogen mitigated liver injury induced by CCl4 treatment in vivo. Estrogen supplementation significantly restored liver damage induced by OVX and CCl4. Comparative analysis revealed significant alterations in pathways including aminoacyl-tRNA biosynthesis, glycine, serine, and threonine metabolism, lysine degradation, and taurine and hypotaurine metabolism in estrogen treatment.

CONCLUSION

Estrogen supplementation alleviates liver injury induced by OVX and CCl4, highlighting its protective effects against fibrosis and associated metabolic alterations.

GC-MS validation and analysis of targeted plasma metabolites related to carbonyl stress in type 2 diabetes mellitus patients with and without acute coronary syndrome

Methylglyoxal (MG) is responsible for advanced glycation end-product formation, the mechanisms leading to diabetes pathogenesis and complications like acute coronary syndrome (ACS). Sugar metabolites, amino acids and fatty acids are possible substrates for MG. The study aimed to measure plasma MG substrate levels using a validated gas chromatography-mass spectrometry (GC-MS) method and explore their association with ACS risk in type 2 diabetes mellitus (T2DM). The study included 150 T2DM patients with ACS as cases and 150 T2DM without ACS as controls for the analysis of glucose, fructose, ribulose, sorbitol, glycerol, pyruvate, lactate, glycine, serine, threonine, C16:0, C16:1, C18:0, C18:1, C18:2, C18:3, C20:0 and C22:6 by GC-MS. Validated GC-MS methods were accurate, precise and sensitive. Cases significantly differed in plasma MG and metabolite levels except for lactate, C16:0, C18:0, C18:2, and C18:3 levels compared with controls. On multivariable logistic regression, plasma C20:0, C18:1, glycine and glycerol levels had increased odds of ACS risk. On multivariate receiver operating characteristic analysis, a model containing plasma C20:0, C16:1, C18:1, C18:2, serine, glycerol, lactate and threonine levels had the highest area under the curve value (0.932) for ACS diagnosis. In conclusion, plasma C20:0, C16:1, C18:1, glycine, glycerol and sorbitol levels were associated with ACS risk in T2DM.

Dry blood spots as a sampling strategy to identify insulin resistance markers during a dietary challenge

This study aimed to identify markers of postprandial dysglycemia in the blood of self-described healthy individuals using dry blood spots (DBS) as a sampling strategy. A total of 54 volunteers, including 31 women, participated in a dietary challenge. They consumed a high-fat, high-sugar mixed meal and underwent multiple blood sampling over the course of 150 min to track their postprandial responses. Blood glucose levels were monitored with a portable glucometer and individuals were classified into two groups based on the glucose area under the curve (AUC): High-AUC (H-AUC) and Low-AUC (L-AUC). DBS sampling was performed at the same time points as the assessment of glycemia using Whatman 903 Protein Saver filter paper. A gas chromatography-mass spectrometry-based metabolite profiling was conducted in the DBS samples to assess postprandial changes in blood metabolome. Higher concentrations of metabolites associated with insulin resistance were observed in individuals from the H-AUC group, including sugars and sugar-derived products such as fructose and threonic acid, as well as organic acids and fatty acids such as succinate and stearic acid. Several metabolites detected in the GC-MS analysis remained unidentified, indicating that other markers of hyperglycemia remain to be discovered in DBS. Based on these observations, we demonstrated that the use of DBS as a non-invasive and inexpensive sampling tool allows the identification of metabolites markers of dysglycemia in the postprandial period.

Metabolomic profiling analysis reveals the benefits of ginseng berry intake on mitochondrial function and glucose metabolism in the liver of obese mice

INTRODUCTION

Ginseng berry (GB) has previously been demonstrated to improve systemic insulin resistance and regulate hepatic glucose metabolism and steatosis in mice with diet-induced obesity (DIO).

OBJECTIVES

In this study, the role of GB in metabolism was assessed using metabolomics analysis on the total liver metabolites of DIO mice.

METHODS

Metabolomic profiling was performed using capillary electrophoresis time-of-flight mass spectrometry (CE-TOF/MS) of liver tissue from mice on a 12-wk normal chow diet (NC), high-fat diet (HFD), and HFD supplemented with 0.1% GB (HFD + GB). The detected metabolites, its pathways, and functions were analyzed through partial least square discriminant analysis (PLS-DA), the small molecular pathway database (SMPDB), and MetaboAnalyst 5.0.

RESULTS

The liver metabolite profiles of NC, HFD, and GB-fed mice (HFD + GB) were highly compartmentalized. Metabolites involved in major liver functions, such as mitochondrial function, gluconeogenesis/glycolysis, fatty acid metabolism, and primary bile acid biosynthesis, showed differences after GB intake. The metabolites that showed significant correlations with fasting blood glucose (FBG), insulin, and homeostatic model assessment for insulin resistance (HOMA-IR) were highly associated with mitochondrial membrane function, energy homeostasis, and glucose metabolism. Ginseng berry intake increased the levels of metabolites involved in mitochondrial membrane function, decreased the levels of metabolites related to glucose metabolism, and was highly correlated with metabolic phenotypes.

CONCLUSION

This study demonstrated that long-term intake of GB changed the metabolite of hepatosteatotic livers in DIO mice, normalizing global liver metabolites involved in mitochondrial function and glucose metabolism and indicating the potential mechanism of GB in ameliorating hyperglycemia in DIO mice.

Opportunities and barriers in omics-based biomarker discovery for steatotic liver diseases

The rising prevalence of liver diseases related to obesity and excessive use of alcohol is fuelling an increasing demand for accurate biomarkers aimed at community screening, diagnosis of steatohepatitis and significant fibrosis, monitoring, prognostication and prediction of treatment efficacy. Breakthroughs in omics methodologies and the power of bioinformatics have created an excellent opportunity to apply technological advances to clinical needs, for instance in the development of precision biomarkers for personalised medicine. Via omics technologies, biological processes from the genes to circulating protein, as well as the microbiome - including bacteria, viruses and fungi, can be investigated on an axis. However, there are important barriers to omics-based biomarker discovery and validation, including the use of semi-quantitative measurements from untargeted platforms, which may exhibit high analytical, inter- and intra-individual variance. Standardising methods and the need to validate them across diverse populations presents a challenge, partly due to disease complexity and the dynamic nature of biomarker expression at different disease stages. Lack of validity causes lost opportunities when studies fail to provide the knowledge needed for regulatory approvals, all of which contributes to a delayed translation of these discoveries into clinical practice. While no omics-based biomarkers have matured to clinical implementation, the extent of data generated has enabled the hypothesis-free discovery of a plethora of candidate biomarkers that warrant further validation. To explore the many opportunities of omics technologies, hepatologists need detailed knowledge of commonalities and differences between the various omics layers, and both the barriers to and advantages of these approaches.

Dietary and circulating branched chain amino acids are unfavorably associated with body fat measures among Chinese adults

Animal studies showed a detrimental effect of dietary branched chain amino acids (BCAAs) on metabolic health, while epidemiological evidence on dietary BCAAs and obesity is limited and inconclusive. We hypothesized that high dietary and circulating BCAAs are unfavorably associated with obesity in community-dwelling adults. We evaluated the 1-year longitudinal associations of dietary BCAA intake and circulating BCAAs with body fat measures. Body weight, height, and circumferences of the waist (WC) and hip (HC) were measured at baseline and again after 1-year. Body composition and liver fat [indicated by controlled attenuation parameter (CAP)] were also assessed after 1-year. Serum BCAA concentrations at baseline were quantified by liquid chromatography mass spectrometry. Diet was collected using 4 quarterly 3-day recalls during the 1-year. The correlation coefficients between dietary and serum BCAAs were 0.12 (P = .035) for total dietary BCAAs, and ranged from -0.02 (soy foods, P = .749) to 0.18 (poultry, P = .001). Total dietary BCAA intake was associated with increase in body weight (β = 0.044, P = .022) and body mass index (BMI, β = 0.047, P = .043). BCAAs from animal foods were associated with increase in HC, while BCAAs from soy foods were associated with weight gain and higher CAP (all P < .05). Serum BCAAs were associated with higher WC, HC, BMI, body fat mass, visceral fat level, and CAP (all P < .05). These results support that dietary and circulating BCAAs are positively associated with the risk of obesity. More cohort studies with validated dietary assessment tools and long-term follow-up among diverse populations are needed to confirm our findings.

Multichannel Nanogenerator-Driven Collaborative Metabolic Fingerprint Diagnostic Strategy for Early Screening and Risk Evaluation of Nonalcoholic Fatty Liver Disease

Nonalcoholic fatty liver disease (NAFLD), along with its progressive forms nonalcoholic steatohepatitis (NASH) and NASH fibrosis, has emerged as a global health crisis. However, the absence of robust screening and risk evaluation tools contributes to the underdiagnosis of NAFLD. Herein, we reported a multichannel nanogenerator-assisted laser desorption/ionization mass spectrometry (LDI-MS) platform for early screening and risk evaluation of NAFLD. Specifically, titanium oxide nanosheets (TiNS) and covalent-organic framework nanosheets (COFNS) were employed as nanogenerators with excellent optical properties and exhibited efficient desorption/ionization during the LDI-MS process. Only ∼0.025 μL of serum without pretreatments and separation, serum metabolic fingerprints (SMFs) can be extracted within seconds. Notably, integrated SMFs from TiNS and COFNS significantly improved diagnostic performance and achieved the area under the curve (AUC) values of 1.000 with 100% sensitivity and 100% specificity for the validation sets of global diagnosis, early diagnosis, high-risk NASH, and NASH fibrosis evaluation. Additionally, four biomarker panels were identified, and their diagnostic AUC values were more than 0.944. Ultimately, key metabolic pathways indicating the change from simple NAFLD to high-risk NASH and NASH fibrosis were uncovered. This work provided a noninvasive and high-throughput screening and risk evaluation strategy for NAFLD healthcare management, thus contributing to the precise treatment of the NALFD.

Investigating the mechanism of cornel iridoid glycosides on type 2 diabetes mellitus using serum and urine metabolites in rats

ETHNOPHARMACOLOGICAL RELEVANCE

Cornel iridoid glycosides (CIG) are extracted from Corni fructus, a herbal medicine used in traditional Chinese medicine to treat diabetes. However, the antidiabetic effects of CIG and the underlying metabolic mechanisms require further exploration.

AIM OF THE STUDY

This study aimed to assess the antidiabetic effects and metabolic mechanism of CIG by performing metabolomic analyses of serum and urine samples of rats.

MATERIALS AND METHODS

A rat model of type 2 diabetes mellitus (T2DM) was established by administering a low dose of streptozotocin (30 mg/kg) intraperitoneally after 4 weeks of feeding a high-fat diet. The model was evaluated based on several parameters, including fasting blood glucose (FBG), random blood glucose (RBG), urine volume, liver index, body weight, histopathological sections, and serum biochemical parameters. Subsequently, serum and urine metabolomics were analyzed using ultra-high-pressure liquid chromatography coupled with linear ion trap-Orbitrap tandem mass spectrometry (UHPLC-LTQ-Orbitrap-MS). Data were analyzed using unsupervised principal component analysis (PCA) and supervised orthogonal partial least squares discriminant analysis (OPLS-DA). Differential metabolites were examined by the Kyoto Encyclopedia of Genes and Genomes (KEGG) metabolic pathways to explore the underlying mechanisms.

RESULTS

After 4 weeks of treatment with different doses of CIG, varying degrees of antidiabetic effects were observed, along with reduced liver and pancreatic injury, and improved oxidative stress levels. Compared with the T2DM group, 19 and 23 differential metabolites were detected in the serum and urine of the CIG treatment group, respectively. The key metabolites involved in pathway regulation include taurine, chenodeoxycholic acid, glycocholic acid, and L-tyrosine in the serum and glycine, hippuric acid, phenylacetylglycine, citric acid, and D-glucuronic acid in the urine, which are related to lipid, amino acid, energy, and carbohydrate metabolism.

CONCLUSIONS

This study confirmed the antidiabetic effects of CIG and revealed that CIG effectively controlled metabolic disorders in T2DM rats. This seems to be meaningful for the clinical application of CIG, and can benefit further studies on CIG mechanism.