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Frontiers in Immunology 2024Mycobacterium tuberculosis (Mtb) is an intracellular pathogen capable of adapting and surviving within macrophages, utilizing host nutrients for its growth and... (Review)
Review
Mycobacterium tuberculosis (Mtb) is an intracellular pathogen capable of adapting and surviving within macrophages, utilizing host nutrients for its growth and replication. Cholesterol is the main carbon source during the infection process of Mtb. Cholesterol metabolism in macrophages is tightly associated with cell functions such as phagocytosis of pathogens, antigen presentation, inflammatory responses, and tissue repair. Research has shown that Mtb infection increases the uptake of low-density lipoprotein (LDL) and cholesterol by macrophages, and enhances cholesterol synthesis in macrophages. Excessive cholesterol is converted into cholesterol esters, while the degradation of cholesterol esters in macrophages is inhibited by Mtb. Furthermore, Mtb infection suppresses the expression of ATP-binding cassette (ABC) transporters in macrophages, impeding cholesterol efflux. These alterations result in the massive accumulation of cholesterol in macrophages, promoting the formation of lipid droplets and foam cells, which ultimately facilitates the persistent survival of Mtb and the progression of tuberculosis (TB), including granuloma formation, tissue cavitation, and systemic dissemination. Mtb infection may also promote the conversion of cholesterol into oxidized cholesterol within macrophages, with the oxidized cholesterol exhibiting anti-Mtb activity. Recent drug development has discovered that reducing cholesterol levels in macrophages can inhibit the invasion of Mtb into macrophages and increase the permeability of anti-tuberculosis drugs. The development of drugs targeting cholesterol metabolic pathways in macrophages, as well as the modification of existing drugs, holds promise for the development of more efficient anti-tuberculosis medications.
Topics: Mycobacterium tuberculosis; Cholesterol; Humans; Macrophages; Tuberculosis; Animals; Host-Pathogen Interactions; Antitubercular Agents; Lipid Metabolism
PubMed: 38873598
DOI: 10.3389/fimmu.2024.1402024 -
Frontiers in Cell and Developmental... 2024Lipid droplets (LDs) serve as intracellular compartments primarily dedicated to the storage of metabolic energy in the form of neutral lipids. The processes that... (Review)
Review
Lipid droplets (LDs) serve as intracellular compartments primarily dedicated to the storage of metabolic energy in the form of neutral lipids. The processes that regulate and control LD biogenesis are being studied extensively and are gaining significance due to their implications in major metabolic disorders, including type 2 diabetes and obesity. A protein of particular interest is Fat storage-Inducing Transmembrane 2 (FIT2), which affects the emergence step of LD biogenesis. Instead of properly emerging towards the cytosol, LDs in FIT2-deficient cells remain embedded within the membrane of the endoplasmic reticulum (ER). studies revealed the ability of FIT2 to bind both di- and triacylglycerol (DAG/TAG), key players in lipid storage, and its activity to cleave acyl-CoA. However, the translation of these functions to the observed embedding of LDs in FIT2 deficient cells remains to be established. To understand the role of FIT2 , we discuss the parameters that affect LD emergence. Our focus centers on the role that membrane curvature and surface tension play in LD emergence, as well as the impact that the lipid composition exerts on these key parameters. In addition, we discuss hypotheses on how FIT2 could function locally to modulate lipids at sites of LD emergence.
PubMed: 38872930
DOI: 10.3389/fcell.2024.1422032 -
Food Chemistry Jun 2024This study explored how co-oleogelator type, concentration, and water addition affect lipid digestion and β-carotene (βC) bioaccessibility in corn oil oleogels....
This study explored how co-oleogelator type, concentration, and water addition affect lipid digestion and β-carotene (βC) bioaccessibility in corn oil oleogels. Oleogels containing 0.1% βC, 20% glyceryl stearate (GS), with lecithin (L) or hydrogenated lecithin (HL) (at 0, 0.5, or 2.5%) and their water-filled counterparts (1% water) were examined. In vitro intestinal digestion revealed HL-oleogels experienced higher lipolysis due to their smaller crystal size enhancing surface area for lipase action, whereas L-oleogels presented lower digestibility, attributed to larger oil droplets and a minimized surface area. Water addition didn't significantly change lipid digestibility. βC bioaccessibility was inversely related to co-oleogelator concentration, with L-oleogels demonstrating the largest decrease, likely due to less free fatty acids released for micelle formation. However, water-filled oleogels enhanced βC bioaccessibility. These findings highlight that tailored microstructure in oleogels can control lipid digestion and βC bioaccessibility, paving the way for designing efficient delivery systems for targeted nutrient delivery.
PubMed: 38870810
DOI: 10.1016/j.foodchem.2024.139978 -
Adipocyte Dec 2024Adipose tissue plays a crucial role in metabolic syndrome, autoimmune diseases, and many cancers. Because of adipose's role in so many aspects of human health, there is...
Adipose tissue plays a crucial role in metabolic syndrome, autoimmune diseases, and many cancers. Because of adipose's role in so many aspects of human health, there is a critical need for in vitro models that replicate adipose architecture and function. Traditional monolayer models, despite their convenience, are limited, showing heterogeneity and functional differences compared to 3D models. While monolayer cultures struggle with detachment and inefficient differentiation, healthy adipocytes in 3D culture accumulate large lipid droplets, secrete adiponectin, and produce low levels of inflammatory cytokines. The shift from monolayer models to more complex 3D models aims to better replicate the physiology of healthy adipose tissue in culture. This study introduces a simple and accessible protocol for generating adipose organoids using a scaffold-free spheroid model. The method, utilizing either 96-well spheroid plates or agarose micromolds, demonstrates increased throughput, uniformity, and ease of handling compared to previous techniques. This protocol allows for diverse applications, including drug testing, toxin screening, tissue engineering, and co-culturing. The choice between the two methods depends on the experimental goals, with the 96-well plate providing individualized control and the micromold offering scale advantages. The outlined protocol covers isolation, expansion, and characterization of stromal vascular fraction cells, followed by detailed steps for spheroid formation and optional downstream analyses.
Topics: Spheroids, Cellular; Adipose Tissue; Humans; Adipocytes; Cell Culture Techniques; Animals; Tissue Engineering; Cells, Cultured; Cell Differentiation; Mice
PubMed: 38864486
DOI: 10.1080/21623945.2024.2347215 -
Nature Communications Jun 2024Assessing the impact of SARS-CoV-2 on organelle dynamics allows a better understanding of the mechanisms of viral replication. We combine label-free holotomographic...
Assessing the impact of SARS-CoV-2 on organelle dynamics allows a better understanding of the mechanisms of viral replication. We combine label-free holotomographic microscopy with Artificial Intelligence to visualize and quantify the subcellular changes triggered by SARS-CoV-2 infection. We study the dynamics of shape, position and dry mass of nucleoli, nuclei, lipid droplets and mitochondria within hundreds of single cells from early infection to syncytia formation and death. SARS-CoV-2 infection enlarges nucleoli, perturbs lipid droplets, changes mitochondrial shape and dry mass, and separates lipid droplets from mitochondria. We then used Bayesian network modeling on organelle dry mass states to define organelle cross-regulation networks and report modifications of organelle cross-regulation that are triggered by infection and syncytia formation. Our work highlights the subcellular remodeling induced by SARS-CoV-2 infection and provides an Artificial Intelligence-enhanced, label-free methodology to study in real-time the dynamics of cell populations and their content.
Topics: SARS-CoV-2; Humans; COVID-19; Mitochondria; Bayes Theorem; Lipid Droplets; Artificial Intelligence; Cell Nucleolus; Virus Replication; Cell Nucleus; Animals; Chlorocebus aethiops; Vero Cells
PubMed: 38862527
DOI: 10.1038/s41467-024-49260-7 -
European Heart Journal Open May 2024Chronic neurohormonal activation and haemodynamic load cause derangement in the utilization of the myocardial substrate. In this study, we test the hypothesis that the...
AIMS
Chronic neurohormonal activation and haemodynamic load cause derangement in the utilization of the myocardial substrate. In this study, we test the hypothesis that the primary mitral regurgitation (PMR) heart shows an altered metabolic gene profile and cardiac ultra-structure consistent with decreased fatty acid and glucose metabolism despite a left ventricular ejection fraction (LVEF) > 60%.
METHODS AND RESULTS
Metabolic gene expression in right atrial (RA), left atrial (LA), and left ventricular (LV) biopsies from donor hearts ( = 10) and from patients with moderate-to-severe PMR ( = 11) at surgery showed decreased mRNA glucose transporter type 4 (GLUT4), GLUT1, and insulin receptor substrate 2 and increased mRNA hexokinase 2, O-linked -acetylglucosamine transferase, and O-linked -acetylglucosaminyl transferase, rate-limiting steps in the hexosamine biosynthetic pathway. Pericardial fluid levels of neuropeptide Y were four-fold higher than simultaneous plasma, indicative of increased sympathetic drive. Quantitative transmission electron microscopy showed glycogen accumulation, glycophagy, increased lipid droplets (LDs), and mitochondrial cristae lysis. These findings are associated with increased mRNA for glycogen synthase kinase 3β, decreased carnitine palmitoyl transferase 2, and fatty acid synthase in PMR vs. normals. Cardiac magnetic resonance and positron emission tomography for 2-deoxy-2-[F]fluoro-D-glucose ([F]FDG) uptake showed decreased LV [F]FDG uptake and increased plasma haemoglobin A1C, free fatty acids, and mitochondrial damage-associated molecular patterns in a separate cohort of patients with stable moderate PMR with an LVEF > 60% ( = 8) vs. normal controls ( = 8).
CONCLUSION
The PMR heart has a global ultra-structural and metabolic gene expression pattern of decreased glucose uptake along with increased glycogen and LDs. Further studies must determine whether this presentation is an adaptation or maladaptation in the PMR heart in the clinical evaluation of PMR.
PubMed: 38854954
DOI: 10.1093/ehjopen/oeae034 -
PeerJ 2024Cisplatin is a commonly used nephrotoxic drug and can cause acute kidney injury (AKI). In the present study, isobaric tags for relative and absolute quantification...
BACKGROUND
Cisplatin is a commonly used nephrotoxic drug and can cause acute kidney injury (AKI). In the present study, isobaric tags for relative and absolute quantification (iTRAQ) and parallel reaction monitoring (PRM)-based comparative proteomics were used to analyze differentially expressed proteins (DEPs) to determine the key molecular mechanism in mice with cisplatin-induced AKI in the presence or absence of SIS3, a specific p-smad3 inhibitor, intervention.
METHODS
The cisplatin-induced AKI mouse model was established and treated with SIS3. We used iTRAQ to search for DEPs, PRM to verify key DEPs and combined Gene Ontology (GO) and Kyoto Encyclopedia of Genes and Genomes (KEGG) for bioinformatics analysis. We then assessed lipid deposition, malondialdehyde (MDA) and reactive oxygen species (ROS) and detected the expression of SREBF1, SCD1, CPT1A, PPARα and NDRG1 in vitro.
RESULTS
Proteomic analysis showed that the identified DEPs were mainly enriched in energy metabolism pathways, especially in lipid metabolism. When SIS3 was applied to inhibit the phosphorylation of Smad3, the expression of NDRG1 and fatty acid oxidation key proteins CPT1A and PPARα increased, the expression of lipid synthesis related proteins SREBF1 and SCD1 decreased and the production of lipid droplets, MDA and ROS decreased.
CONCLUSION
SIS3 alleviates oxidative stress, reduces lipid accumulation and promotes fatty acid oxidation through NDRG1 in cisplatin-induced AKI. Our study provides a new candidate protein for elucidating the molecular mechanisms of fatty acid metabolism disorders in cisplatin-induced acute kidney injury.
Topics: Cisplatin; Animals; Acute Kidney Injury; Proteomics; Mice; Disease Models, Animal; Male; Smad3 Protein; Lipid Metabolism; Oxidative Stress; Reactive Oxygen Species; Antineoplastic Agents
PubMed: 38854800
DOI: 10.7717/peerj.17485 -
Journal of Dairy Science Jun 2024Hepatocellular lipid accumulation characterizes fatty liver in dairy cows. Lipid droplets (LD), specialized organelles that store lipids and maintain cellular lipid...
Hepatocellular lipid accumulation characterizes fatty liver in dairy cows. Lipid droplets (LD), specialized organelles that store lipids and maintain cellular lipid homeostasis, are responsible for the ectopic storage of lipids associated with several metabolic disorders. In recent years, non-ruminant studies have reported that LD-mitochondria interactions play an important role in lipid metabolism. Due to the role of diacylglycerol acyltransferase isoforms (DGAT1 and DGAT2) in LD synthesis, we explored mechanisms of mitochondrial fatty acid transport in ketotic cows using liver biopsies and isolated primary hepatocytes. Compared with healthy cows, cows with fatty liver had massive accumulation of LD and high protein expression of the triglyceride (TAG) synthesis-related enzymes DGAT1 and DGAT2, LD synthesis-related proteins perilipin 2 (PLIN2) and perilipin 5 (PLIN5), and the mitochondrial fragmentation-related proteins dynamin-related protein 1 (DRP1) and fission 1 (FIS1). In contrast, factors associated with fatty acid oxidation, mitochondrial fusion and mitochondrial electron transport chain complex were lower compared with those in the healthy cows. In addition, transmission electron microscopy revealed significant contacts between LD-mitochondria in liver tissue from cows with fatty liver. Compared with isolated cytoplasmic mitochondria, expression of carnitine palmitoyl transferase 1A (CPT1A) and DRP1 was lower, but mitofusin 2 (MFN2) and mitochondrial electron transport chain complex was greater in isolated peridroplet mitochondria from hepatic tissue of cows with fatty liver. In vitro data indicated that exogenous free fatty acids (FFA) induced hepatocyte LD synthesis and mitochondrial dynamics consistent with in vivo results. Furthermore, DGAT2 inhibitor treatment attenuated the FFA-induced upregulation of PLIN2 and PLIN5 and rescued the impairment of mitochondrial dynamics. Inhibition of DGAT2 also restored mitochondrial membrane potential and reduced hepatocyte reactive oxygen species production. The present in vivo and in vitro results indicated there are functional differences among different types of mitochondria in the liver tissue of dairy cows with ketosis. Activity of DGAT2 may play a key role in maintaining liver mitochondrial function and lipid homeostasis in dairy cows during the transition period.
PubMed: 38851581
DOI: 10.3168/jds.2024-24738 -
AMB Express Jun 2024Aromatic compounds are known anti-amyloid aggregates. Their effect on amorphous aggregates of proteins is, however, less studied. We chose aromatic amino acids Trp, Tyr,...
Aromatic compounds are known anti-amyloid aggregates. Their effect on amorphous aggregates of proteins is, however, less studied. We chose aromatic amino acids Trp, Tyr, and Phe, as well as another known stabilizer (i.e. Arg), as potential compatible solvents to be tested on Bacillus amyloliquefaciens alpha-amylase (BAA). Among these additives, Phe was the only one to be effective on the thermal inactivation and amorphous aggregation of BAA, while preserving its intrinsic activity. A concentration of 50 mM Phe was used to test its potential in counteracting the deleterious effect of BAA amorphous aggregates in vivo. After 21 days of daily subcutaneous injections of the native enzyme to mice, amorphous aggregates of BAA, as well as aggregates produced in presence of 50 mM Phe, the tissues located at the site of injection were studied histologically. Amorphous aggregates caused an increase in macrophages and lipid droplets. Serum levels of IL6 and TNF-α were also accordingly elevated and indicative of an inflammation state. Aggregates also resulted into increased levels of glucose, triglycerides and cholesterol, as well as liver enzymes SGOT and SGPT. On the other hand, the presence of Phe prevented this exacerbated inflammatory state and the subsequent impairment of biochemical parameters. In conclusion, Phe is an interesting compound for both stabilizing proteins and counteracting the pathological effect of amorphous aggregates.
PubMed: 38850460
DOI: 10.1186/s13568-024-01712-5 -
STAR Protocols Jun 2024Chicken cone cells are an excellent model for studying the regulation of lipid droplet dynamics. Here, we present a protocol for studying cone cell lipid droplets from...
Chicken cone cells are an excellent model for studying the regulation of lipid droplet dynamics. Here, we present a protocol for studying cone cell lipid droplets from in vivo and ex vitro cultured retinas of chicken embryos. We describe steps for dissecting chicken retinas, electroporating retinas, culturing retinas ex vivo and in vitro, and staining lipid droplets with neutral lipid dye. This protocol is also applicable to investigating other organelles in retinas. For complete details on the use and execution of this protocol, please refer to Pan et al..
Topics: Animals; Lipid Droplets; Chick Embryo; Chickens; Retinal Cone Photoreceptor Cells; Retina
PubMed: 38843400
DOI: 10.1016/j.xpro.2024.103113