3-carboxy-4-methyl-5-propyl-2-furanpropanoic acid (CMPF) prevents high fat diet-induced insulin resistance via maintenance of hepatic lipid homeostasis

Investigating the impact of human blood metabolites on the Sepsis development and progression: a study utilizing two-sample Mendelian randomization

Background

Existing data suggests a potential link between human blood metabolites and sepsis, yet the precise cause-and-effect relationship remains elusive. By using a two-sample Mendelian randomization (MR) analysis, this study aims to establish a causal link between human blood metabolites and sepsis.

Methods

A two-sample MR analysis was employed to investigate the relationship between blood metabolites and sepsis. To assess the causal connection between sepsis and human blood metabolites, five different MR methods were employed, A variety of sensitivity analyses were conducted, including Cochrane's Q test, MR-Egger intercept test, MR-PRESSO and leave-one-out (LOO) analysis. In order to ensure the robustness of the causal association between exposure and outcome, the Bonferroni adjustment was employed. Additionally, we conducted analyses of the metabolic pathways of the identified metabolites using the Kyoto Encyclopedia of Genes and Genomes (KEGG) and the Small Molecule Pathway Database (SMPDB) database.

Results

The MR analysis revealed a total of 27 metabolites (16 known and 11 unknown) causally linked to the development and progression of sepsis. After applying the Bonferroni correction, 3-carboxy-4-methyl-5-propyl-2-furanpropanoate (CMPF) remained significant in relation to 28-day all-cause mortality in sepsis. By pathway enrichment analysis, we identified four significant metabolic pathways. Notably, the Alpha Linolenic Acid and Linoleic Acid metabolism pathway emerged as a pivotal contributor to the occurrence and progression of sepsis.

Conclusion

This study provides preliminary evidence of causal associations between human blood metabolites and sepsis, as ascertained by MR analysis. The findings offer valuable insights into the pathogenesis of sepsis and may provide insight into preventive and therapeutic approaches.

Furan fatty acid extracted from Hevea brasiliensis latex increases muscle mass in mice

Skeletal muscle is essential for locomotion and plays a crucial role in energy homeostasis. It is regulated by nutrition, genetic factors, physical activity and hormones. Furan fatty acids (FuFAs) are minor fatty acids present in small quantities in food from plants and animals origin. Recently, we showed that a preventive nutritional supplementation with furan fatty acid in a DIO mouse model reduces metabolic disorders. The present study was designed to determine the influence of FuFA-F2 extracted from Hevea brasiliensis latex on skeletal muscle phenotype. In C2C12 myotubes we found that FuFA-F2 whatever the concentration used increased protein content. We revealed that in C2C12 myotubes FuFA-F2 (10 µM) increases protein synthesis as shown by the stimulation of mTOR phosphorylation. Next, to confirm in vivo our results C57Bl6 mice were supplemented by oral gavage with vehicle or FuFA-F2 (20 mg/kg) for 3 and a half weeks. We found that mice supplemented with FuFA-F2 had a greater lean mass than the control mice. In line with this observation, we revealed that FuFA-F2 increased muscle mass and promoted more oxidative muscle metabolism in mice as attested by cytochrome c oxidase activity. In conclusion, we demonstrated that FuFA-F2 stimulates muscle anabolism in mice in vitro and in vivo, mimicking in part physical activity. This study highlights that in vivo FuFA-F2 may have health benefits by increasing muscle mass and oxidative metabolism.

Association of Plasma Selenium and Its Untargeted Metabolomic Profiling with Cervical Cancer Prognosis

Selenium is an essential trace element that shows beneficial or adverse health effects depending on the dose. However, its role in the prognosis of cervical cancer (CC) has been less reported. We aimed to explore the association between selenium status and prognosis in CC patients with different prognoses and to elucidate the underlying mechanism of selenium in CC prognosis. This cross-sectional observational study had a case-control design at the Harbin Medical University Cancer Hospital and was conducted using 29 CC cases with poor prognosis and 29 CC cases with good prognosis. Plasma selenium levels were measured using an atomic fluorescence spectrometer. Untargeted metabolomics was used to identify metabolites. Plasma selenium levels of the poor prognosis group (49.90 ± 13.81 µg/L) were lower than that of the good prognosis group (59.38 ± 13.00 µg/L, t = 2.69, P = 0.009). In the logistic regression analysis, plasma selenium levels were associated with lower poor prognosis risk [odds ratio (OR) = 0.952, 95% CI: 0.909-0.998]. Receiver operating characteristic curve analysis revealed an optimal cut-off point of plasma selenium levels ≤ 47.68 µg/L for poor prognosis of CC. Based on the cut-off selenium levels, patients with different prognoses were divided into high and low selenium groups. Metabolomic analysis revealed six differential metabolites among different prognoses with low and high selenium levels, and the glycerophospholipid (GPL) metabolism was enriched. Plasma selenium levels were positively correlated with metabolite levels. Our findings provided evidence that low plasma selenium levels may associate with a poor prognosis of CC. Low plasma selenium levels might suppress GPL metabolism and influence the prognosis of CC. This finding requires confirmation in future prospective cohort studies.

3-Carboxy-4-methyl-5-propyl-2-furanpropanoic acid (CMPF) induces cell death through ferroptosis and acts as a trigger of apoptosis in kidney cells

Ferroptosis is a cell death mechanism characterized by intracellular iron accumulation and lipid peroxidation. Effects of uremic toxins on ferroptosis in the kidney are not well understood. We investigated whether protein-bound uremic toxins induce ferroptosis, resulting in cell death, using the bilateral ureteral obstruction (BUO) mouse model and kidney cells. In BUO mice, we observed elevated lipid peroxidation, increased iron concentration, and decreased glutathione peroxidase 4 (GPX4) expression. Levels of transferrin receptor 1 and system Xc-, which are involved in iron transport and storage, were also elevated, while those of ferritin heavy and light chains (FHC and FLC) were reduced. Treatment of HK-2 and NRK49F kidney cells with CMPF decreased GSH levels and the expression of GPX4, FHC, and FLC, and increased levels of ROS, lipid peroxidation, and intracellular iron concentration. CMPF-induced and erastin-induced decreases in GPX4 levels and increases in Bax and cytochrome C levels were counteracted by ferrostatin-1 pretreatment. However, GPX4 mRNA levels, protein abundance, or promoter activity were not restored by Z-VAD-FMK, a multi-caspase inhibitor. These results suggest that ferroptosis induced by CMPF treatment induces apoptosis, and inhibition of ferroptosis reduces apoptosis, suggesting that ferroptosis plays a role in triggering cell death by apoptosis.

Adaptive Changes in Glucose Homeostasis and Islet Function During Pregnancy: A Targeted Metabolomics Study in Mice

OBJECTIVE

Pregnancy is a dynamic state involving multiple metabolic adaptions in various tissues including the endocrine pancreas. However, a detailed characterization of the maternal islet metabolome in relation to islet function and the ambient circulating metabolome during pregnancy has not been established.

METHODS

A timed-pregnancy mouse model was studied, and age-matched non-pregnant mice were used as controls. Targeted metabolomics was applied to fasting plasma and purified islets during each trimester of pregnancy. Glucose homeostasis and islet function was assessed. Bioinformatic analyses were performed to reveal the metabolic adaptive changes in plasma and islets, and to identify key metabolic pathways associated with pregnancy.

RESULTS

Fasting glucose and insulin were found to be significantly lower in pregnant mice compared to non-pregnant controls, throughout the gestational period. Additionally, pregnant mice had superior glucose excursions and greater insulin response to an oral glucose tolerance test. Interestingly, both alpha and beta cell proliferation were significantly enhanced in early to mid-pregnancy, leading to significantly increased islet size seen in mid to late gestation. When comparing the plasma metabolome of pregnant and non-pregnant mice, phospholipid and fatty acid metabolism pathways were found to be upregulated throughout pregnancy, whereas amino acid metabolism initially decreased in early through mid pregnancy, but then increased in late pregnancy. Conversely, in islets, amino acid metabolism was consistently enriched throughout pregnancy, with glycerophospholid and fatty acid metabolism was only upregulated in late pregnancy. Specific amino acids (glutamate, valine) and lipids (acyl-alkyl-PC, diacyl-PC, and sphingomyelin) were found to be significantly differentially expressed in islets of the pregnant mice compared to controls, which was possibly linked to enhanced insulin secretion and islet proliferation.

CONCLUSION

Beta cell proliferation and function are elevated during pregnancy, and this is coupled to the enrichment of islet metabolites and metabolic pathways primarily associated with amino acid and glycerophospholipid metabolism. This study provides insight into metabolic adaptive changes in glucose homeostasis and islet function seen during pregnancy, which will provide a molecular rationale to further explore the regulation of maternal metabolism to avoid the onset of pregnancy disorders, including gestational diabetes.

Vascepa protects against high-fat diet-induced glucose intolerance, insulin resistance, and impaired β-cell function

Omega-3 fatty acid prescription drugs, Vascepa (≥96% eicosapentaenoic acid [EPA] ethyl ester) and Lovaza (46.5% EPA and 37.5% docosahexaenoic acid ethyl ester) are known therapeutic regimens to treat hypertriglyceridemia. However, their impact on glucose homeostasis, progression to type 2 diabetes, and pancreatic beta cell function are not well understood. In the present study, mice were treated with Vascepa or Lovaza for one week prior to six weeks of high-fat diet feeding. Vascepa but not Lovaza led to reduced insulin resistance, reduced fasting insulin and glucose, and improved glucose intolerance. Vascepa improved beta cell function, reduced liver triglycerides with enhanced expression of hepatic fatty acid oxidation genes, and altered microbiota composition. Vascepa has protective effects on diet-induced insulin resistance and glucose intolerance in mice.

Effects of GPR18 Ligands on Body Weight and Metabolic Parameters in a Female Rat Model of Excessive Eating

GPR18 has been proposed to play a role in the progression of metabolic disease and obesity. Therefore, the aim of this study was to determine the effects of selective GRP18 ligands (the antagonists PSB-CB5 and PSB-CB27 and the agonist PSB-KK1415) on body mass and the development of metabolic disorders commonly accompanying obesity. Experiments were carried out on female Wistar rats. In order to determine the anorectic activity of the investigated ligands, their effect on food and water intake in a model of excessive eating was assessed. Lipid profile, glucose and insulin levels as well as alanine aminotransferase, aspartate aminotransferase, and γ-glutamyl transpeptidase activity in plasma were also evaluated. Potential side effects were examined in rat models of pica behavior and conditioned taste aversion. Animals treated with different ligands gained significantly less weight than rats from the obese control group. Effects of GPR18 antagonists on food intake and body weight were specific and unrelated to visceral illness, stress or changes in spontaneous activity. However, the GPR18 agonist is likely to affect body weight by inducing gastrointestinal disorders such as nausea. The presented preliminary data support the idea that the search for selective GPR18 antagonists for the treatment of obesity might be promising.

Development of a sensitive and quantitative method for the identification of two major furan fatty acids in human plasma

This article focuses on the establishment of an accurate and sensitive quantitation method for the analysis of furan fatty acids. In particular, the sensitivity of GC/MS and UPLC/ESI/MS/MS was compared for the identification and quantification of furan fatty acids. Different methylation methods were tested with respect to GC/MS analysis. Special attention needs to be paid to the methylation of furan fatty acids, as acidic catalysts might lead to the degradation of the furan ring. GC/MS analysis in full-scan mode demonstrated that the limit of quantitation was 10 μM. UPLC/ESI/MS/MS in multiple reaction monitoring mode displayed a higher detection sensitivity than GC/MS. Moreover, the identification of furan fatty acids with charge-reversal derivatization was tested in the positive mode with two widely used pyridinium salts. Significant oxidation was unexpectedly observed using N-(4-aminomethylphenyl) pyridinium as a derivatization agent. The formed 3-acyl-oxymethyl-1-methylpyridinium iodide derivatized by 2-bromo-1-methylpyridinium iodide and 3-carbinol-1-methylpyridinium iodide improved the sensitivity more than 2,000-fold compared with nonderivatization in the negative mode by UPLC/ESI/MS/MS. This charge-reversal derivatization enabled the targeted quantitation of furan fatty acids in human plasma. Thus, it is anticipated that this protocol could greatly contribute to the clarification of pathological mechanisms related to furan fatty acids and their metabolites.

Pure omega 3 polyunsaturated fatty acids (EPA, DPA or DHA) are associated with increased plasma levels of 3-carboxy-4-methyl-5-propyl-2-furanpropanoic acid (CMPF) in a short-term study in women

3-Carboxy-4-methyl-5-propyl-2-furanpropanoic acid (CMPF) is a metabolite of furan fatty acids found in plasma and urine. Our data show that purified EPA, DPA and DHA may also be precursors of CMPF; however the metabolic pathway(s) remain unclear.

Serum 3-carboxy-4-methyl-5-propyl-2-furanpropanoic acid is associated with lipid profiles and might protect against non-alcoholic fatty liver disease in Chinese individuals

AIMS/INTRODUCTION

High plasma 3-carboxy-4-methyl-5-propyl-2-furanpropanoic acid (CMPF) levels are significantly associated with type 2 diabetes mellitus, which is usually accompanied by metabolic syndrome and non-alcoholic fatty liver disease (NAFLD) with increased triglyceride levels. Thus, we hypothesized that elevated CMPF levels might be related to lipid metabolism and NAFLD risk.

MATERIALS AND METHODS

Serum CMPF levels were determined using an enzyme-linked immunosorbent assay in a total of 466 individuals, including 116 controls with no NAFLD or type 2 diabetes mellitus, 53 individuals with NAFLD but no type 2 diabetes mellitus, 151 individuals with type 2 diabetes mellitus but no NAFLD, and 146 individuals with both NAFLD and type 2 diabetes mellitus. The associations with age, blood pressure, lipid profiles, body mass index and liver injury marker levels were examined, and a meta-analysis of non-diabetic and diabetic groups was carried out to detect the combined effects.

RESULTS

The CMPF concentration in NAFLD patients was significantly lower than individuals without NAFLD in both the non-diabetic group (P < 0.05) and diabetic group (P < 0.01), and correlated negatively with several parameters of liver function and the adiposity index. Meta-analysis showed that serum CMPF levels was associated with decreased risk of NAFLD after combining the results (odds ratio 0.677, 95% confidence interval 0.552-0.831, P < 0.001). Additionally, the CMPF concentration was independently negatively associated with triglycerides and high-density lipoprotein cholesterol in the meta-analysis. Multiple stepwise regression analysis showed that body mass index, high-density lipoprotein cholesterol, triglyceride level, age, sex and fasting plasma glucose were independently associated with CMPF (all P < 0.05).

CONCLUSIONS

The results suggest that serum CMPF levels are negatively related to lipid metabolism and could be used to predict NAFLD development.