Circulating fatty acids from high-throughput metabolomics platforms as potential biomarkers of dietary fatty acids

Dietary polyunsaturated fatty acid and risk of gout: a cohort study integrating genetic predisposition and metabolomics

OBJECTIVES

Gout is the most common inflammatory arthritis and affects quality of life. Dietary polyunsaturated fatty acids (PUFAs) have protective effects against various diseases, but its role in gout remains uncertain. Our study aims to assess the association between PUFAs intake and gout risk, the role of genetic factors, and the possible impact of metabolites.

METHODS

This study included 198,033 participants who were free of gout at baseline and completed at least one reliable dietary assessment in the UK Biobank. Cox proportional hazard models were used to estimate the associations between PUFAs intake and gout risk, and the modified effects of genetic predisposition. Mediation analysis also explored the mediating role of metabolic signature in associations between specific PUFAs intake and gout.

RESULTS

Over a median follow-up of 9.47 years, 1,708 incident cases of gout were recorded. Gout risk was significantly associated with the second quartile of linoleic acid (LA) (0.86 [0.75, 1.00]) intake and the highest quartiles of alpha-linolenic acid (ALA) (0.72 [0.62, 0.84]), total PUFA (HR: 0.84 [95% CI:0.71, 0.99]), n-6 PUFA (0.84 [0.71, 0.99]), n-3 PUFA (0.83 [0.71, 0.98]), and eicosapentaenoic acid (EPA) (0.79 [0.68, 0.91]), compared to the lowest quartiles. We observed joint effects of PUFAs intake and genetic susceptibility on gout risk. Mediation analysis showed that high-density lipoprotein (HDL) and triglycerides mediated the associations of ALA and LA with gout risk.

CONCLUSION

Our findings suggested the potential benefits of PUFAs in reducing gout risk, particularly vegetable sources, with HDL and triglycerides as key mediators.

New insights on mesenchymal stem cells therapy from the perspective of the pathogenesis of nonalcoholic fatty liver disease

Nonalcoholic fatty liver disease (NAFLD) manifests as chronic hepatic steatosis, occurring variably across people due to racial and genetic diversity. It represents a stage in the development of chronic liver disease, marked by fat accumulation, inflammatory responses, oxidative stress in the endoplasmic reticulum, and fibrosis as primary concerns. Understanding its underlying mechanisms remains a challenging and pivotal area of study. In the past, acute liver injury-related diseases were commonly treated with methods such as liver transplantation. However, the emergence of artificial liver has shifted focus to stem cell therapies. Unlike conventional drugs, stem cell therapies are continuously evolving. Despite being classified as drugs, stem cells demonstrated significant efficacy after multiple injections. Mesenchymal stem cells, unlike other types of stem cells, do not have the risk of tumor formation and low immunogenicity, reducing the hypersensitivity reactions associated with liver transplantation. Increasingly, studies suggest that mesenchymal stem cells hold promise in the treatment of chronic liver injury diseases. This review focuses on investigating the role of mesenchymal stem cells in chronic metabolic liver diseases, such as non-alcoholic fatty liver disease, and delves into their specific functions.

Application of attenuated total reflection-Fourier transform infrared spectroscopy in semi-quantification of blood lipids and characterization of the metabolic syndrome

BACKGROUND/PURPOSE

Dyslipidemia, a hallmark of metabolic syndrome (MetS), contributes to atherosclerotic and cardiometabolic disorders. Due to days-long analysis, current clinical procedures for cardiotoxic blood lipid monitoring are unmet. This study used AI-assisted attenuated total reflectance Fourier transform infrared (ATR-FTIR) spectroscopy to identify MetS and precisely quantify multiple blood lipid levels with a blood sample of 0.5 µl and the assaying time is approximately 10 minutes.

METHODS

ATR-FTIR spectroscopy with 1738 data points in the spectral range of 4000-650 cm-1 was used to analyze the blood samples. An adaptive synthetic technique was used to establish a prevalence-balanced dataset. LDL-C, HDL-C, TG, VLDL-C, and cholesterol levels were defined as the predicted targets of lipid absorption profiles. Linear regression (LR), gradient boosting regression tree (GBT), and histogram-based gradient boosting regression tree (HGBTR) were used to train the models. Lipid profile value prediction was evaluated using R2 and MAE, whereas MetS prediction was evaluated using area under the ROC curve.

RESULTS

A total of 150 blood samples from 25 individuals without MetS and 25 with MetS yielded 491 spectral measurements. In the regression models, HGBT best predicted the targets of TG, CHOL, HDL-C, LDL-C, and VLDL-C with R2 values of 0.854 (0.12), 0.684 (0.08), 0.758 (0.10), and 0.419 (0.11), respectively. The classification model with the greatest AUC was RF (0.978), followed by HGBT (0.972) and GBT (0.967).

CONCLUSION

The results of this study revealed that predicting MetS and determining blood lipid levels with high R2 values and limited errors are feasible for monitoring during therapy and intervention.

Non-targeted metabolomics and explainable artificial intelligence: Effects of processing and color on coniferyl aldehyde levels in Eucommiae cortex

Eucommia ulmoides, a plant native to China, is valued for its medicinal properties and has applications in food, health products, and traditional Chinese medicine. Processed Eucommiae Cortex (EC) has historically been a highly valued medicine. Ancient doctors had ample experience processing EC, especially with ginger juice, as documented in traditional Chinese medical texts. The combination of EC and ginger juice helps release and transform the active ingredients, strengthening the medicine's effectiveness and improving its taste and shelf life. However, the lack of quality control standards for Ginger-Eucommiae Cortex (G-EC), processed from EC and ginger, presents challenges for its industrial and clinical use. This study optimized G-EC processing using the CRITIC and Box-Behnken methods. Metabolomics showed 517 chemical changes between raw and processed G-EC, particularly an increase in coniferyl aldehyde (CFA). Explainable artificial intelligence techniques revealed the feasibility of using color to CFA content, providing insights into quality indicators.

Circulating fatty acids and risk of severe non-alcoholic fatty liver disease in the UK biobank: a prospective cohort of 116 223 individuals

Fatty acid (FA) metabolism plays an important role in the development of nonalcoholic fatty liver disease (NAFLD). However, data on the relationship between circulating FAs and NAFLD risk are limited. This study aims to assess the associations between specific circulating FAs and severe NAFLD risk among the general population. Overall 116 223 participants without NAFLD and other liver diseases from the UK Biobank were enrolled between 2006 and 2010 and were followed up until the end of 2021. Plasma concentrations of saturated fatty acids (SFAs), monounsaturated fatty acids (MUFAs), and polyunsaturated fatty acids (PUFAs) were analyzed using an NMR-based biomarker profiling platform. Hazard ratios (HRs) and 95% confidence intervals (CIs) of NAFLD risk were estimated using Cox proportional-hazard models adjusted for other potential confounders. During a mean follow-up of 12.3 years, we documented 1394 cases of severe NAFLD. After multivariate adjustment, plasma SFAs and MUFAs were associated with a higher risk of severe NAFLD, whereas plasma n-3 PUFAs, n-6 PUFAs, and linoleic acid (LA) were associated with a lower risk. As compared with the lowest quartile, HRs (95% CIs) of severe NAFLD risk in the highest quartiles were 1.85 (1.45-2.36) for SFAs, 1.74 (1.23-2.44) for MUFAs, 0.79 (0.65-0.97) for n-3 PUFAs, 0.68 (0.48-0.96) for n-6 PUFAs, and 0.73 (0.54-0.99) for LA. The significant relationships were mainly mediated by serum TG for SFAs, HDL-C for MUFAs and n-6 PUFAs, and C-reactive protein for n-3 PUFAs. Plasma SFAs were associated with a more pronounced increase in the risk of severe NAFLD among participants with fewer SFA-associated alleles (P interaction = 0.032). Dietary recommendations for reducing plasma SFAs and MUFAs while increasing n-3 and n-6 PUFAs may be protective for severe NAFLD, which could be mediated by lipid metabolism and inflammation.

Plasma metabolites of a healthy lifestyle in relation to mortality and longevity: Four prospective US cohort studies

BACKGROUND

A healthy lifestyle is associated with a lower premature mortality risk and with longer life expectancy. However, the metabolic pathways of a healthy lifestyle and how they relate to mortality and longevity are unclear. We aimed to identify and replicate a healthy lifestyle metabolomic signature and examine how it is related to total and cause-specific mortality risk and longevity.

METHODS

In four large cohorts with 13,056 individuals and 28-year follow-up, we assessed five healthy lifestyle factors, used liquid chromatography mass spectrometry to profile plasma metabolites, and ascertained deaths with death certificates. The unique healthy lifestyle metabolomic signature was identified using an elastic regression. Multivariable Cox regressions were used to assess associations of the signature with mortality and longevity.

FINDINGS

The identified healthy lifestyle metabolomic signature was reflective of lipid metabolism pathways. Shorter and more saturated triacylglycerol and diacylglycerol metabolite sets were inversely associated with the healthy lifestyle score, whereas cholesteryl ester and phosphatidylcholine plasmalogen sets were positively associated. Participants with a higher healthy lifestyle metabolomic signature had a 17% lower risk of all-cause mortality, 19% for cardiovascular disease mortality, and 17% for cancer mortality and were 25% more likely to reach longevity. The healthy lifestyle metabolomic signature explained 38% of the association between the self-reported healthy lifestyle score and total mortality risk and 49% of the association with longevity.

CONCLUSIONS

This study identifies a metabolomic signature that measures adherence to a healthy lifestyle and shows prediction of total and cause-specific mortality and longevity.

FUNDING

This work was funded by the NIH, CIHR, AHA, Novo Nordisk Foundation, and SciLifeLab.

Diet composition, nutrient substitutions and circulating fatty acids in relation to ectopic and visceral fat depots

BACKGROUND & AIMS

Short-term randomized trials have demonstrated that replacing saturated fat (SFA) with polyunsaturated fat (PUFA) causes a reduction or prevention of liver fat accumulation, but population-based studies on diet and body fat distribution are limited. We investigated cross-sectional associations between diet, circulating fatty acids and liver fat, visceral adipose tissue (VAT), intermuscular adipose tissue (IMAT) and other fat depots using different energy-adjustment models.

METHODS

Sex-stratified analyses of n = 9119 (for serum fatty acids) to 13 849 (for nutrients) participants in UK Biobank were conducted. Fat depots were assessed by MRI, circulating fatty acids by NMR spectroscopy and diet by repeated 24-h recalls. Liver fat, VAT and IMAT were primary outcomes; total adipose tissue (TAT) and abdominal subcutaneous adipose tissue (ASAT) were secondary outcomes. Three a priori defined models were constructed: the all-components model, standard model and leave-one-out model (main model including specified nutrient substitutions). Imiomics (MRI-derived) was used to confirm and visualize associations.

RESULTS

In women, substituting carbohydrates and free sugars with saturated fat (SFA) was positively associated with liver fat (β (95% CI) = 0.19 (0.02, 0.36) and β (95% CI) = 0.20 (0.05-0.35), respectively) and IMAT (β (95% CI) = 0.07 (0.00, 0.14) and β (95% CI) = 0.08 (0.02, 0.13), respectively), whereas substituting animal fat with plant fat was inversely associated with IMAT, ASAT and TAT. In the all-components and standard models, SFA and animal fat were positively associated with liver fat, IMAT and VAT whereas plant fat was inversely associated with IMAT in women. Few associations were observed in men. Circulating polyunsaturated fatty acids (PUFA) were inversely associated with liver fat, IMAT and VAT in both men and women, whereas SFA and monounsaturated fatty acids were positively associated.

CONCLUSIONS

Type of dietary fat may be an important determinant of ectopic fat in humans consuming their habitual diet. Plant fat and PUFA should be preferred over animal fat and SFA. This is corroborated by circulating fatty acids and overall consistent through different energy adjustment models.

TWITTER SUMMARY

In UK Biobank, intake of saturated- and animal fat were positively whereas biomarkers of polyunsaturated fat were inversely associated with liver-, visceral- and intermuscular fat. Type of dietary fat may be a determinant of ectopic fat, a risk factor for cardiometabolic disease.