Higher intakes of lysine, threonine and valine are inversely associated with non-alcoholic fatty liver disease risk: a community-based case-control study in the Chinese elderly

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.

Gut Microbiota Predicts Treatment Response to Empagliflozin Among MASLD Patients Without Diabetes Mellitus

BACKGROUND AND AIM

We aimed to investigate whether gut microbiota could predict the treatment response to pharmacological agents among metabolic dysfunction-associated steatotic liver disease (MASLD) patients without diabetes mellitus (DM), as data are lacking.

METHODS

We prospectively followed up non-diabetic MASLD patients who used empagliflozin. Clinical, anthropometric, laboratory assessments and magnetic resonance imaging-proton density fat fraction (MRI-PDFF) were performed from baseline to week 52 (EOT). Baseline stool samples were collected, and shotgun DNA metagenomic sequencing was performed to profile microbiome. The primary outcome was treatment response to empagliflozin at EOT, defined as MRI-PDFF decline ≥ 30% at EOT from baseline. Linear discriminant analysis [LDA] effect size was used to identify putative bacterial species. Multivariable logistic regression was used to derive adjusted odds ratio (aOR) of outcome with bacterial species by adjusting for clinical factors.

RESULTS

Twenty-two (48.9%) of 45 patients (median age: 56.9 years [IQR: 51.0-63.2]; male: 23 [51.1%]) achieved treatment response at EOT. There was difference in alpha diversity (Shannon index: p < 0.001; Simpson index: p = 0.001) and beta diversity (p = 0.048) in baseline microbiome between treatment response and non-response groups. Faecalibacterium prausnitzii (log10LDAscore = 4.27), Lachnospira pectinoschiza (log10LDAscore = 3.99), Anaerostipes hadrus (log10LDAscore = 3.98), Roseburia faecis (log10LDAscore = 3.97), Roseburia inulinivorans (log10LDAscore = 3.58) and Agathobaculum butyriciproducens (log10LDAscore = 2.77) were enriched in the treatment response group. L. pectinoschiza (aOR: 34.1; p = 0.015), A. hadrus (aOR:35.0; p = 0.032) and A. butyriciproducens (aOR:22.3; p = 0.023) independently predicted treatment response but not clinical factors. These three species collectively predicted treatment response with AUROC of 0.89 (95% CI: 0.80-0.99).

CONCLUSIONS

Certain gut bacterial species, particularly the combination of A. hadrus, L. pectinoschiza and A. butyriciproducens, may predict treatment response to empagliflozin in MAFLD patients without DM.

A novel rhodamine B fluorescence probe for rapid identification of different amino acids by high efficiency fluorescence spectrum-mass spectrometry

Introduction

Rapid detection of amino acids plays an important role in the field of medical diagnosis. By combining Rhodamine B with triphenylamine, a novel double-response fluorescence probe (E)-4-((4-(((3',6'-bis(diethylamino)-3-oxospiro[isoindoline-1,9'-xanthen]-2-yl)imino)methyl)phenyl)(phenyl)amino)benzaldehyde (RBTPA) was prepared for rapid identification of different amino acids.

Methods

Under daylight and 365 nm irradiation, it was found that the color change was most bright at pH = 3, and changed to dim at pH = 4. When pH = 3 and pH = 4, the photophysical properties of the two strong acids are very different. The maximum redshift of UV absorption light is 110 nm, and the maximum fluorescence emission intensity is 4 times different.

Results and Discussion

In order to further observe their binding structure analysis with different amino acids, qualitative analysis of each response structure was determined by mass spectrometry according to different molecular weights. The fluorescence probe RBTPA has two different isomers for recognition response in aldehyde group and imine group, respectively.

Improved Risk Prediction of Acute Myocardial Infarction in Patients With Stable Coronary Artery Disease Using an Amino Acid-Assisted Model

Patients with stable coronary artery disease (CAD) are at an increased risk of acute myocardial infarction (AMI), particularly among older individuals. Developing a reliable model to predict AMI occurrence in these patients holds the potential to expedite early diagnosis and intervention. This study is aimed at establishing a circulating amino acid-assisted model, incorporating amino acid profiles alongside clinical variables, to predict AMI risk. A cohort of 874 CAD patients from two independent centers was analyzed. Plasma amino acid levels were quantified using liquid chromatography tandem mass spectrometry (LC-MS/MS) employing a targeted metabolomics approach. This methodology incorporated 13C isotope-labeled internal standards for precise quantification of 27 amino acids. Univariate logistic regression was applied to identify differentially expressed amino acids that distinguished between stable CAD and AMI patients. To assess prediction performance, receiver operating characteristic (ROC) curve and nomogram analyses were utilized. Five amino acids-lysine, methionine, tryptophan, tyrosine, and N6-trimethyllysine-emerged as potential biomarkers (p < 0.05), exhibiting significant differences in their expression levels across the two centers when comparing stable CAD with AMI patients. For AMI risk prediction, the base model, utilizing 12 clinical variables, achieved areas under the curve (AUC) of 0.7387 in the discovery phase (n = 623) and 0.8205 in the external validation set (n = 251). Notably, the integration of these five amino acids into the prediction model significantly enhanced its performance, increasing the AUC to 0.7651 in the discovery phase (Delong's test, p = 1.43e-02) and to 0.8958 in the validation set (Delong's test, p = 8.91e-03). In conclusion, the circulating amino acid-assisted model effectively enhances the prediction of AMI risk among CAD patients, indicating its potential clinical utility in facilitating early detection and intervention.

Aminophenylboronic acid-modified nitrogen-doped graphene quantum dots and their applications in lysine sensing based on interplaying fluorescent mechanisms

Using nitrogen-doped graphene quantum dots (N-GQDs) and 3-aminophenylboronic acid (APBA), a novel fluorescence nanosensor was developed. This nanosensor exhibits high selectivity and sensitivity for lysine detection. Its sensing mechanism involves the suppression of electron transfer from APBA to the N-GQDs unit, thereby inhibiting photoinduced electron transfer and initiating internal charge transfer. At an optimal pH of 7, the protonated α-amine and ε-amine groups of lysine interact with the amide and boronic acid moieties, respectively. This interaction results in a redshift of fluorescence, substantially enhancing the response signal. A linear response was observed within a concentration range 0.40-3.01 μM, with the detection limit being 0.005 μM. A similar linear range was also achieved for the determination of lysine in human serum. Density functional theory calculations correlating molecular orbits and geometries support UV-vis and fluorescence findings. Additionally, the nanosensor was successfully applied to detect lysine in living cells and real samples, including milk and honey. For practical application, we construct a lysine-specific sensing platform using a commercial chip (TCS34725) that collects red, blue, and green signals, thereby facilitating the convenient use of the nanosensor. Overall, this study offers new perspectives on the development and application of fluorescent nanosensors for detecting individual amino acids.

Management of Metabolic-Associated Fatty Liver Disease/Metabolic Dysfunction-Associated Steatotic Liver Disease: From Medication Therapy to Nutritional Interventions

Non-alcoholic fatty liver disease (NAFLD) is a common long-lasting liver disease that affects millions of people around the world. It is best identified with a hepatic fat build-up that ultimately leads to inflammation and damage. The classification and nomenclature of NAFLD have long been a controversial topic, until 2020 when a group of international experts recommended substituting NAFLD with MAFLD (metabolic dysfunction-associated FLD). MAFLD was then terminologically complemented in 2023 by altering it to MASLD, i.e., metabolic dysfunction-associated steatotic liver disease (MASLD). Both the MAFLD and the MASLD terminologies comprise the metabolic element of the disorder, as they offer diagnostic benchmarks that are embedded in the metabolic risk factors that underlie the disease. MASLD (as a multisystemic disease) provides a comprehensive definition that includes a larger population of patients who are at risk of liver morbidity and mortality, as well as adverse cardiovascular and diabetes outcomes. MASLD highlights metabolic risks in lean or normal weight individuals, a factor that has not been accentuated or discussed in previous guidelines. Novel antihyperglycemic agents, anti-hyperlipidemic drugs, lifestyle modifications, nutritional interventions, and exercise therapies have not been extensively studied in MAFLD and MASLD. Nutrition plays a vital role in managing both conditions, where centralizing on a diet rich in whole vegetables, fruits, foods, healthy fats, lean proteins, and specific nutrients (e.g., omega-3 fatty acids and fibers) can improve insulin resistance and reduce inflammation. Thus, it is essential to understand the role of nutrition in managing these conditions and to work with patients to develop an individualized plan for optimal health. This review discusses prevention strategies for NAFLD/MAFLD/MASLD management, with particular attention to nutrition and lifestyle correction.

A Novel Bifidobacterium longum ssp. longum Strain with Pleiotropic Effects

Postbiotics are gaining increasing interest among the scientific community as well as at the level of food processing enterprises. The aim of this preliminary study was to characterise the metabolic diversity of a novel Bifidobacterium longum strain, BIOCC 1719, of human origin. The change after 24 h cultivation in three media was assessed using a metabolomic approach. Milk-based substrates favoured the activity of the strain, promoting the production of B vitamins, essential amino acids, bile acids, and fatty acids. Vitamins B1, B2, B6, B7, and B12 (with an average increase of 20-30%) were produced in both whole milk and whey; the increased production in the latter was as high as 100% for B7 and 744% for B12. The essential amino acids methionine and threonine were produced (>38%) in both milk and whey, and there was an increased production of leucine (>50%) in milk and lysine (126%) in whey. Increases in the content of docosahexaenoic acid (DHA) by 20%, deoxycholic acid in milk and whey (141% and 122%, respectively), and cholic acid (52%) in milk were recorded. During the preliminary characterisation of the metabolic diversity of the novel B. longum strain, BIOCC 1719, we identified the bioactive compounds produced by the strain during fermentation. This suggests its potential use as a postbiotic ingredient to enrich the human diet.

Serum metabolomic profiling unveils distinct sex-related metabolic patterns in NAFLD

Objective

Obesity poses an increased risk for the onset of Nonalcoholic fatty liver disease (NAFLD). The influence of other factors, such as sex in the incidence and severity of this liver disease has not yet been fully elucidated. Thus, we aimed to identify the NAFLD serum metabolic signatures associated with sex in normal, overweight and obese patients and to associate the metabolite fluctuations across the increasing liver steatosis stages.

Methods and results

Using nuclear magnetic resonance (NMR) serum samples of 210 NAFLD cases and control individuals diagnosed with liver U/S, our untargeted metabolomics enquiry provided a sex distinct metabolic bouquet. Increased levels of alanine, histidine and tyrosine are associated with severity of NAFLD in both men and women. Moreover, higher serum concentrations of valine, aspartic acid and mannose were positively associated with the progression of NAFLD among the male subjects, while a negative association was observed with the levels of creatine, phosphorylcholine and acetic acid. On the other hand, glucose was positively associated with the progression of NAFLD among the female subjects, while levels of threonine were negatively related. Fluctuations in ketone bodies acetoacetate and acetone were also observed among the female subjects probing a significant reduction in the circulatory levels of the former in NAFLD cases. A complex glycine response to hepatic steatosis of the female subjects deserves further investigation.

Conclusion

Results of this study aspire to address the paucity of data on sex differences regarding NAFLD pathogenesis. Targeted circulatory metabolome measurements could be used as diagnostic markers for the distinct stages of NAFLD in each sex and eventually aid in the development of novel sex-related therapeutic options.

Plasma Amino Acids in NAFLD Patients with Obesity Are Associated with Steatosis and Fibrosis: Results from the MAST4HEALTH Study

Non-alcoholic fatty liver disease (NAFLD) and non-alcoholic steatohepatitis (NASH) have been linked to changes in amino acid (AA) levels. The objective of the current study was to examine the relationship between MRI parameters that reflect inflammation and fibrosis and plasma AA concentrations in NAFLD patients. Plasma AA levels of 97 NAFLD patients from the MAST4HEALTH study were quantified with liquid chromatography. Medical, anthropometric and lifestyle characteristics were collected and biochemical parameters, as well as inflammatory and oxidative stress biomarkers, were measured. In total, subjects with a higher MRI-proton density fat fraction (MRI-PDFF) exhibited higher plasma AA levels compared to subjects with lower PDFF. The concentrations of BCAAs (p-Value: 0.03), AAAs (p-Value: 0.039), L-valine (p-Value: 0.029), L-tyrosine (p-Value: 0.039) and L-isoleucine (p-Value: 0.032) were found to be significantly higher in the higher PDFF group compared to lower group. Plasma AA levels varied according to MRI-PDFF. Significant associations were also demonstrated between AAs and MRI-PDFF and MRI-cT1, showing the potential utility of circulating AAs as diagnostic markers of NAFLD.