Membrane States of Saturated Glycerophospholipids: A Thermodynamic Study of Bilayer Phase Transitions

LPCAT1-mediated membrane phospholipid remodelling promotes ferroptosis evasion and tumour growth

The mechanisms underlying the dynamic remodelling of cellular membrane phospholipids to prevent phospholipid peroxidation-induced membrane damage and evade ferroptosis, a non-apoptotic form of cell death driven by iron-dependent lipid peroxidation, remain poorly understood. Here we show that lysophosphatidylcholine acyltransferase 1 (LPCAT1) plays a critical role in ferroptosis resistance by increasing membrane phospholipid saturation via the Lands cycle, thereby reducing membrane levels of polyunsaturated fatty acids, protecting cells from phospholipid peroxidation-induced membrane damage and inhibiting ferroptosis. Furthermore, the enhanced in vivo tumour-forming capability of tumour cells is closely associated with the upregulation of LPCAT1 and emergence of a ferroptosis-resistant state. Combining LPCAT1 inhibition with a ferroptosis inducer synergistically triggers ferroptosis and suppresses tumour growth. Therefore, our results unveil a plausible role for LPCAT1 in evading ferroptosis and suggest it as a promising target for clinical intervention in human cancer.

Inhibitory Properties of Cinnamon Bark Oil against Postharvest Pathogen Penicillium digitatum In Vitro

Penicillium digitatum is a major postharvest pathogen that threatens the global citrus fruit industry and causes great economic losses annually. In the present study, inhibitory properties of cinnamon bark oil (CBO) against P. digitatum in vitro were investigated. Results indicated that 0.03% CBO could efficiently inhibit the spore germination, germ tube elongation, mycelial growth, colonial expansion and conidial accumulation of P. digitatum. The results of fluorescein diacetate (FDA) and MitoTraker Orange (MTO) staining also proved the suppression effects of CBO against P. digitatum. Meanwhile, CBO could inhibit green mold rots induced by P. digitatum in citrus fruit when the working concentration of CBO exceeded 0.06%. In addition, the expressions of 12 genes critical for the growth and virulence of P. digitatum were also significantly regulated under CBO stress. Through a transcriptomic analysis, a total of 1802 common differentially expressed genes (DEGs) were detected in P. digitatum after 4 h and 8 h of CBO treatment. Most of the DEG products were associated with carbohydrate, amino acid and lipid metabolism. They directly or indirectly led to the disturbance of the membrane and the generation of reactive oxygen species (ROS). Our results may deepen the understanding of antifungal properties of CBO against P. digitatum and provide the theoretical foundation to uncover the antifungal mechanism of CBO at the molecular level.

Metabolomic Profiling of Plasma Reveals Differential Disease Severity Markers in COVID-19 Patients

The severity, disabilities, and lethality caused by the coronavirus 2019 (COVID-19) disease have dumbfounded the entire world on an unprecedented scale. The multifactorial aspect of the infection has generated interest in understanding the clinical history of COVID-19, particularly the classification of severity and early prediction on prognosis. Metabolomics is a powerful tool for identifying metabolite signatures when profiling parasitic, metabolic, and microbial diseases. This study undertook a metabolomic approach to identify potential metabolic signatures to discriminate severe COVID-19 from non-severe COVID-19. The secondary aim was to determine whether the clinical and laboratory data from the severe and non-severe COVID-19 patients were compatible with the metabolomic findings. Metabolomic analysis of samples revealed that 43 metabolites from 9 classes indicated COVID-19 severity: 29 metabolites for non-severe and 14 metabolites for severe disease. The metabolites from porphyrin and purine pathways were significantly elevated in the severe disease group, suggesting that they could be potential prognostic biomarkers. Elevated levels of the cholesteryl ester CE (18:3) in non-severe patients matched the significantly different blood cholesterol components (total cholesterol and HDL, both p < 0.001) that were detected. Pathway analysis identified 8 metabolomic pathways associated with the 43 discriminating metabolites. Metabolomic pathway analysis revealed that COVID-19 affected glycerophospholipid and porphyrin metabolism but significantly affected the glycerophospholipid and linoleic acid metabolism pathways (p = 0.025 and p = 0.035, respectively). Our results indicate that these metabolomics-based markers could have prognostic and diagnostic potential when managing and understanding the evolution of COVID-19.

Magnesium Isoglycyrrhizinate Reduces Hepatic Lipotoxicity through Regulating Metabolic Abnormalities

The excessive accumulation of lipids in hepatocytes induces a type of cytotoxicity called hepatic lipotoxicity, which is a fundamental contributor to liver metabolic diseases (such as NAFLD). Magnesium isoglycyrrhizinate (MGIG), a magnesium salt of the stereoisomer of natural glycyrrhizic acid, is widely used as a safe and effective liver protectant. However, the mechanism by which MGIG protects against NAFLD remains unknown. Based on the significant correlation between NAFLD and the reprogramming of liver metabolism, we aimed to explore the beneficial effects of MGIG from a metabolic viewpoint in this paper. We treated HepaRG cells with palmitic acid (PA, a saturated fatty acid of C16:0) to induce lipotoxicity and then evaluated the antagonistic effect of MGIG on lipotoxicity by investigating the cell survival rate, DNA proliferation rate, organelle damage, and endoplasmic reticulum stress (ERS). Metabolomics, lipidomics, and isotope tracing were used to investigate changes in the metabolite profile, lipid profile, and lipid flux in HepaRG cells under different intervention conditions. The results showed that MGIG can indeed protect hepatocytes against PA-induced cytotoxicity and ERS. In response to the metabolic abnormality of lipotoxicity, MGIG curtailed the metabolic activation of lipids induced by PA. The content of total lipids and saturated lipids containing C16:0 chains increased significantly after PA stimulation and then decreased significantly or even returned to normal levels after MGIG intervention. Lipidomic data show that glycerides and glycerophospholipids were the two most affected lipids. For excessive lipid accumulation in hepatocytes, MGIG can downregulate the expression of the metabolic enzymes (GPATs and DAGTs) involved in triglyceride biosynthesis. In conclusion, MGIG has a positive regulatory effect on the metabolic disorders that occur in hepatocytes under lipotoxicity, and the main mechanisms of this effect are in lipid metabolism, including reducing the total lipid content, reducing lipid saturation, inhibiting glyceride and glycerophospholipid metabolism, and downregulating the expression of metabolic enzymes in lipid synthesis.

Fluoride exposure altered metabolomic profile in rat serum

It is well known that serum is an ideal and potential choice to reflect the toxicity of fluoride. However, the effects of fluoride on serum metabolome have not been reported until now. In this study, the models of 3-week-old rats exposed fluoride by breast milk and 11-week-old rats exposed fluoride via breast milk and drinking water containing sodium fluoride (100 mg/L) were established. Using Ultra Performance Liquid Chromatography-Mass Spectrometry/Mass Spectrometry (UPLC-MS/MS), as compared with control group, 28 negative (NEG) and 52 positive (POS) metabolites were significantly up-regulated, meanwhile 30 NEG and 21 POS significantly down-regulated metabolites were found in serum of 3-week-old rats exposed to fluoride. For 11-week-old fluorosis rats, there were 119 NEG and 65 POS metabolites significantly increased, and 7 NEG, 5 POS metabolites were obviously decreased. Importantly, nicotinamide, adenosine, 1-Oleoyl-sn-glycero-3-phosphocholine (OGPC), and 1-Stearoyl-sn-glycerol 3-phosphocholine (SGPC) were shared by two models. The metabolites of urea cycle, such as urea and N2-Acetyl-l-ornithine, betaine as a methyl donor, were regarded to reflect the fluorosis degree. These metabolites could be the potential markers of fluorosis, contributing to the prevention and treatment of fluorosis.