Relationship of Circulating Fatty Acid Profile to Metabolic Disorders Associated with Insulin Resistance

Smith AA, Giles C, Huynh K, Cinel M, Mellett NA, Cadby G, Hung J, Hui J, Beilby J, Watts GF, Shaw JS, Moses EK, Magliano DJ, Meikle PJ. High-coverage plasma lipidomics reveals novel sex-specific lipidomic fingerprints of age and BMI: Evidence from two large population cohort studies

Obesity and related metabolic diseases show clear sex-related differences. The growing burden of these diseases calls for better understanding of the age- and sex-related metabolic consequences. High-throughput lipidomic analyses of population-based cohorts offer an opportunity to identify disease-risk-associated biomarkers and to improve our understanding of lipid metabolism and biology at a population level. Here, we comprehensively examined the relationship between lipid classes/subclasses and molecular species with age, sex, and body mass index (BMI). Furthermore, we evaluated sex specificity in the association of the plasma lipidome with age and BMI. Some 747 targeted lipid measures, representing 706 molecular lipid species across 36 classes/subclasses, were measured using a high-performance liquid chromatography coupled mass spectrometer on a total of 10,339 participants from the Australian Diabetes, Obesity and Lifestyle Study (AusDiab), with 563 lipid species being validated externally on 4,207 participants of the Busselton Health Study (BHS). Heat maps were constructed to visualise the relative differences in lipidomic profile between men and women. Multivariable linear regression analyses, including sex-interaction terms, were performed to assess the associations of lipid species with cardiometabolic phenotypes. Associations with age and sex were found for 472 (66.9%) and 583 (82.6%) lipid species, respectively. We further demonstrated that age-associated lipidomic fingerprints differed by sex. Specific classes of ether-phospholipids and lysophospholipids (calculated as the sum composition of the species within the class) were inversely associated with age in men only. In analyses with women alone, higher triacylglycerol and lower lysoalkylphosphatidylcholine species were observed among postmenopausal women compared with premenopausal women. We also identified sex-specific associations of lipid species with obesity. Lysophospholipids were negatively associated with BMI in both sexes (with a larger effect size in men), whilst acylcarnitine species showed opposing associations based on sex (positive association in women and negative association in men). Finally, by utilising specific lipid ratios as a proxy for enzymatic activity, we identified stearoyl CoA desaturase (SCD-1), fatty acid desaturase 3 (FADS3), and plasmanylethanolamine Δ1-desaturase activities, as well as the sphingolipid metabolic pathway, as constituent perturbations of cardiometabolic phenotypes. Our analyses elucidate the effect of age and sex on lipid metabolism by offering a comprehensive view of the lipidomic profiles associated with common cardiometabolic risk factors. These findings have implications for age- and sex-dependent lipid metabolism in health and disease and suggest the need for sex stratification during lipid biomarker discovery, establishing biological reference intervals for assessment of disease risk.

Chemical Analysis of Astragali Complanati Semen and Its Hypocholesterolemic Effect Using Serum Metabolomics Based on Gas Chromatography-Mass Spectrometry

The hypocholesterolemic protective effect of the dried seed of Astragalus complanatus (ACS) was investigated in rats fed with normal diet, high cholesterol diet (HCD), and HCD plus 70% ethanol extract of ACS (600 mg/kg/day) by oral gavage for four weeks. ACS extract was tested to be rich in antioxidants, which may be contributed to its high content of phenolic compounds. Consumption of ACS remarkably suppressed the elevated total cholesterol (p < 0.01) and LDL-C (p < 0.001) induced by HCD. Chemical constituents of ACS extract were analyzed by ultra-performance liquid chromatography coupled with electrospray ionization orbitrap mass spectrometry and the results showed that the ACS extract mainly consisted of phenolic compounds including flavonoids and flavonoid glycosides. In addition, based on the serum fatty acid profiles, elucidated using gas chromatography-mass spectrometry, free and esterified fatty acids including docosapentaenoic acid, adrenic acid, dihomo-γ-linolenic acid and arachidonic acid were regulated in ACS treatment group. Western blot results further indicated the protein expression of peroxisome proliferator-activated receptor alpha (PPARα) (p < 0.05) in liver was upregulated in ACS treatment group. To conclude, our results clearly demonstrated that ACS provides beneficial effect on lowering HCD associated detrimental change.

A lipidomic study on the regulation of inflammation and oxidative stress targeted by marine ω-3 PUFA and polyphenols in high-fat high-sucrose diets

The ability of polyphenols to ameliorate potential oxidative damage of ω-3 PUFAs when they are consumed together and then, to enhance their potentially individual effects on metabolic health is discussed through the modulation of fatty acids profiling and the production of lipid mediators. For that, the effects of the combined consumption of fish oils and grape seed procyanidins on the inflammatory response and redox unbalance triggered by high-fat high-sucrose (HFHS) diets were studied in an animal model of Wistar rats. A standard diet was used as control. Results suggested that fish oils produced a replacement of ω-6 by ω-3 PUFAs in membranes and tissues, and consequently they improved inflammatory and oxidative stress parameters: favored the activity of 12/15-lipoxygenases on ω-3 PUFAs, enhanced glutathione peroxidases activity, modulated proinflammatory lipid mediators synthesis through the cyclooxygenase (COX) pathways and down-regulated the synthesis de novo of ARA leaded by Δ5 desaturase. Although polyphenols exerted an antioxidative and antiinflammatory effect in the standard diet, they were less effective to reduce inflammation in the HFHS dietary model. Contrary to the effect observed in the standard diet, polyphenols up-regulated COX pathways toward ω-6 proinflammatory eicosanoids as PGE₂ and 11-HETE and decreased the detoxification of ω-3 hydroperoxides in the HFHS diet. As a result, additive effects between fish oils and polyphenols were found in the standard diet in terms of reducing inflammation and oxidative stress. However, in the HFHS diets, fish oils seem to be the one responsible for the positive effects found in the combined group.