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Biophysical Journal Oct 2023Lysolipids such as lauroyl, myristoyl, and palmitoyl lysophosphatidylcholine (LPC) insert into the outer leaflet of liposomes but do not flip to the inner leaflet over...
Lysolipids such as lauroyl, myristoyl, and palmitoyl lysophosphatidylcholine (LPC) insert into the outer leaflet of liposomes but do not flip to the inner leaflet over many hours. This way, they create asymmetry stress between the intrinsic areas of the two leaflets. We have studied how this stress is relaxed with particular emphasis on the budding and fission of small (diameter 20-30 nm) daughter vesicles (DVs). Asymmetric flow field-flow fractionation was utilized to quantify the extent of budding from large unilamellar vesicles after exposure to LPC. Budding starts at a low threshold of the order of 2 mol% LPC in the outer (and ≈0 mol% LPC in the inner) leaflet. We see reason to assume that the fractional fluorescence intensity from DVs is a good approximation for the fraction of membrane lipid, POPC, transferred into DVs. Accordingly, budding starts with a "budding power" of ≈6 POPC molecules budding off per LPC added, corresponding to a more than 10-fold accumulation of LPC in the outer leaflet of DVs to ≈24 mol%. As long as budding is possible, little strain is built up in the membranes, a claim supported by the lack of changes in limiting fluorescence anisotropy, rotational correlation time, and fluorescence lifetime of symmetrically and asymmetrically inserted TMA-DPH. At physiological osmolarity, budding is typically limited to 20-30% of budded fraction with some batch-to-batch variation, but independent of the LPC species. We hypothesize that the budding limit is determined by the excess area of the liposomes upon preparation, which is then used up upon budding given the larger area-to-volume ratio of smaller liposomes. As the mother vesicles approach ideal spheres, budding must stop. This is qualitatively supported by increased and decreased budding limits of osmotically predeflated and preinflated vesicles, respectively.
Topics: Liposomes; Unilamellar Liposomes; Membrane Lipids; Fluorescence Polarization; Phosphatidylcholines; Lipid Bilayers
PubMed: 37649254
DOI: 10.1016/j.bpj.2023.08.023 -
Arthritis Research & Therapy Dec 2023Currently, it is not possible to predict whether patients with hyperuricemia (HUA) will develop gout and how this progression may be affected by urate-lowering treatment...
BACKGROUND
Currently, it is not possible to predict whether patients with hyperuricemia (HUA) will develop gout and how this progression may be affected by urate-lowering treatment (ULT). Our study aimed to evaluate differences in plasma lipidome between patients with asymptomatic HUA detected ≤ 40 years (HUA ≤ 40) and > 40 years, gout patients with disease onset ≤ 40 years (Gout ≤ 40) and > 40 years, and normouricemic healthy controls (HC).
METHODS
Plasma samples were collected from 94 asymptomatic HUA (77% HUA ≤ 40) subjects, 196 gout patients (59% Gout ≤ 40), and 53 HC. A comprehensive targeted lipidomic analysis was performed to semi-quantify 608 lipids in plasma. Univariate and multivariate statistics and advanced visualizations were applied.
RESULTS
Both HUA and gout patients showed alterations in lipid profiles with the most significant upregulation of phosphatidylethanolamines and downregulation of lysophosphatidylcholine plasmalogens/plasmanyls. More profound changes were observed in HUA ≤ 40 and Gout ≤ 40 without ULT. Multivariate statistics differentiated HUA ≤ 40 and Gout ≤ 40 groups from HC with an overall accuracy of > 95%.
CONCLUSION
Alterations in the lipidome of HUA and Gout patients show a significant impact on lipid metabolism. The most significant glycerophospholipid dysregulation was found in HUA ≤ 40 and Gout ≤ 40 patients, together with a correction of this imbalance with ULT.
Topics: Humans; Hyperuricemia; Uric Acid; Lipidomics; Gout; Gout Suppressants
PubMed: 38042879
DOI: 10.1186/s13075-023-03204-6 -
Frontiers in Immunology 2023With the extensive use of immunosuppressants, immunosuppression-associated pneumonitis including (PCP) has received increasing attention. Though aberrant adaptive...
INTRODUCTION
With the extensive use of immunosuppressants, immunosuppression-associated pneumonitis including (PCP) has received increasing attention. Though aberrant adaptive immunity has been considered as a key reason for opportunistic infections, the characteristics of innate immunity in these immunocompromised hosts remain unclear.
METHODS
In this study, wild type C57BL/6 mice or dexamethasone-treated mice were injected with or without . Bronchoalveolar lavage fluids (BALFs) were harvested for the multiplex cytokine and metabolomics analysis. The single-cell RNA sequencing (scRNA-seq) of indicated lung tissues or BALFs was performed to decipher the macrophages heterogeneity. Mice lung tissues were further analyzed via quantitative polymerase chain reaction (qPCR) or immunohistochemical staining.
RESULTS
We found that the secretion of both pro-inflammatory cytokines and metabolites in the -infected mice are impaired by glucocorticoids. By scRNA-seq, we identified seven subpopulations of macrophages in mice lung tissues. Among them, a group of Mmp12 macrophages is enriched in the immunocompetent mice with infection. Pseudotime trajectory showed that these Mmp12 macrophages are differentiated from Ly6c classical monocytes, and highly express pro-inflammatory cytokines elevated in BALFs of -infected mice. , we confirmed that dexamethasone impairs the expression of , , and , as well as the fungal killing capacity of alveolar macrophage (AM)-like cells. Moreover, in patients with PCP, we found a group of macrophages resembled the aforementioned Mmp12 macrophages, and these macrophages are inhibited in the patient receiving glucocorticoid treatment. Additionally, dexamethasone simultaneously impaired the functional integrity of resident AMs and downregulated the level of lysophosphatidylcholine, leading to the suppressed antifungal capacities.
CONCLUSION
We reported a group of Mmp12 macrophages conferring protection during infection, which can be dampened by glucocorticoids. This study provides multiple resources for understanding the heterogeneity and metabolic changes of innate immunity in immunocompromised hosts, and also suggests that the loss of Mmp12 macrophages population contributes to the pathogenesis of immunosuppression-associated pneumonitis.
Topics: Mice; Animals; Macrophages, Alveolar; Pneumonia, Pneumocystis; Transcriptome; Glucocorticoids; Matrix Metalloproteinase 12; Multiomics; Mice, Inbred C57BL; Pneumocystis; Cytokines; Immunocompromised Host; Dexamethasone
PubMed: 37359523
DOI: 10.3389/fimmu.2023.1179094 -
The Journal of Clinical Investigation Jun 2023Patients with autosomal recessive microcephaly 15 caused by deficiency in the sodium-dependent lysophosphatidylcholine (LPC) transporter major facilitator superfamily...
Patients with autosomal recessive microcephaly 15 caused by deficiency in the sodium-dependent lysophosphatidylcholine (LPC) transporter major facilitator superfamily domain-containing 2a (Mfsd2a) present with both microcephaly and hypomyelination, suggesting an important role for LPC uptake by oligodendrocytes in the process of myelination. Here we demonstrate that Mfsd2a is specifically expressed in oligodendrocyte precursor cells (OPCs) and is critical for oligodendrocyte development. Single-cell sequencing of the oligodendrocyte lineage revealed that OPCs from OPC-specific Mfsd2a-KO mice (2aOKO mice) underwent precocious differentiation into immature oligodendrocytes and impaired maturation into myelinating oligodendrocytes, correlating with postnatal brain hypomyelination. 2aOKO mice did not exhibit microcephaly, a finding consistent with the notion that microcephaly is the consequence of an absence of LPC uptake at the blood-brain barrier rather than a deficiency in OPCs. Lipidomic analysis showed that OPCs and iOLs from 2aOKO mice had significantly decreased levels of phospholipids containing omega-3 fatty acids, with a corresponding increase in unsaturated fatty acids, the latter being products of de novo synthesis governed by Srebp-1. RNA-Seq indicated activation of the Srebp-1 pathway and defective expression of regulators of oligodendrocyte development. Taken together, these findings indicate that the transport of LPCs by Mfsd2a in OPCs is important for maintaining OPC state to regulate postnatal brain myelination.
Topics: Animals; Mice; Microcephaly; Sterol Regulatory Element Binding Protein 1; Cell Lineage; Symporters; Mice, Knockout; Membrane Transport Proteins; Fatty Acids, Omega-3; Oligodendroglia; Cell Differentiation
PubMed: 37104036
DOI: 10.1172/JCI164118 -
Critical Care (London, England) Jul 2023Prognostication is very important to clinicians and families during the early management of severe traumatic brain injury (sTBI), however, there are no gold standard...
BACKGROUND
Prognostication is very important to clinicians and families during the early management of severe traumatic brain injury (sTBI), however, there are no gold standard biomarkers to determine prognosis in sTBI. As has been demonstrated in several diseases, early measurement of serum metabolomic profiles can be used as sensitive and specific biomarkers to predict outcomes.
METHODS
We prospectively enrolled 59 adults with sTBI (Glasgow coma scale, GCS ≤ 8) in a multicenter Canadian TBI (CanTBI) study. Serum samples were drawn for metabolomic profiling on the 1st and 4th days following injury. The Glasgow outcome scale extended (GOSE) was collected at 3- and 12-months post-injury. Targeted direct infusion liquid chromatography-tandem mass spectrometry (DI/LC-MS/MS) and untargeted proton nuclear magnetic resonance spectroscopy (H-NMR) were used to profile serum metabolites. Multivariate analysis was used to determine the association between serum metabolomics and GOSE, dichotomized into favorable (GOSE 5-8) and unfavorable (GOSE 1-4), outcomes.
RESULTS
Serum metabolic profiles on days 1 and 4 post-injury were highly predictive (Q > 0.4-0.5) and highly accurate (AUC > 0.99) to predict GOSE outcome at 3- and 12-months post-injury and mortality at 3 months. The metabolic profiles on day 4 were more predictive (Q > 0.55) than those measured on day 1 post-injury. Unfavorable outcomes were associated with considerable metabolite changes from day 1 to day 4 compared to favorable outcomes. Increased lysophosphatidylcholines, acylcarnitines, energy-related metabolites (glucose, lactate), aromatic amino acids, and glutamate were associated with poor outcomes and mortality.
DISCUSSION
Metabolomic profiles were strongly associated with the prognosis of GOSE outcome at 3 and 12 months and mortality following sTBI in adults. The metabolic phenotypes on day 4 post-injury were more predictive and significant for predicting the sTBI outcome compared to the day 1 sample. This may reflect the larger contribution of secondary brain injury (day 4) to sTBI outcome. Patients with unfavorable outcomes demonstrated more metabolite changes from day 1 to day 4 post-injury. These findings highlighted increased concentration of neurobiomarkers such as N-acetylaspartate (NAA) and tyrosine, decreased concentrations of ketone bodies, and decreased urea cycle metabolites on day 4 presenting potential metabolites to predict the outcome. The current findings strongly support the use of serum metabolomics, that are shown to be better than clinical data, in determining prognosis in adults with sTBI in the early days post-injury. Our findings, however, require validation in a larger cohort of adults with sTBI to be used for clinical practice.
Topics: Humans; Glasgow Outcome Scale; Chromatography, Liquid; Canada; Tandem Mass Spectrometry; Brain Injuries, Traumatic; Metabolomics; Lactic Acid
PubMed: 37481590
DOI: 10.1186/s13054-023-04573-9 -
EBioMedicine Dec 2023Maternal lipidomic profiling offers promise for characterizing lipid metabolites during pregnancy, but longitudinal data are limited. This study aimed to examine...
BACKGROUND
Maternal lipidomic profiling offers promise for characterizing lipid metabolites during pregnancy, but longitudinal data are limited. This study aimed to examine associations of longitudinal lipidomic profiles during pregnancy with multiple neonatal anthropometry using data from a multiracial cohort.
METHODS
We measured untargeted plasma lipidome profiles among 321 pregnant women from the NICHD Fetal Growth Study-Singletons using plasma samples collected longitudinally during four study visits at gestational weeks (GW) 10-14, 15-26, 23-31, and 33-39, respectively. We evaluated individual lipidomic metabolites at each study visit in association with neonatal anthropometry. We also evaluated the associations longitudinally by constructing lipid networks using weighted correlation network analysis and common networks using consensus network analysis across four visits using linear mixed-effects models with the adjustment of false discover rate.
FINDINGS
Multiple triglycerides (TG) were positively associated with birth weight (BW), BW Z-score, length and head circumference, while some cholesteryl ester (CE), phosphatidylcholine (PC), sphingomyelines (SM), phosphatidylethanolamines (PE), and lysophosphatidylcholines (LPC 20:3) families were inversely associated with BW, length, abdominal and head circumference at different GWs. Longitudinal trajectories of TG, PC, and glucosylcermides (GlcCer) were associated with BW, and CE (18:2) with BW z-score, length, and sum of skinfolds (SS), while some PC and PE were significantly associated with abdominal and head circumference. Modules of TG at GW 10-14 and 15-26 mainly were associated with BW. At GW 33-39, two networks of LPC (20:3) and of PC, TG, and CE, showed inverse associations with abdominal circumference. Distinct trajectories within two consensus modules with changes in TG, CE, PC, and LPC showed significant differences in BW and length.
INTERPRETATION
The results demonstrated that longitudinal changes of TGs during early- and mid-pregnancy and changes of PC, LPC, and CE during late-pregnancy were significantly associated with neonatal anthropometry.
FUNDING
National Institute of Child Health and Human Development intramural funding.
Topics: Infant, Newborn; Child; Pregnancy; Humans; Female; Lipidomics; Anthropometry; Fetal Development; Birth Weight; Lipids
PubMed: 38006745
DOI: 10.1016/j.ebiom.2023.104881 -
The Journal of Neuroscience : the... Jun 2023Although NG2 is known to be selectively expressed in oligodendrocyte precursor cells (OPCs) for many years, its expressional regulation and functional involvement in...
Although NG2 is known to be selectively expressed in oligodendrocyte precursor cells (OPCs) for many years, its expressional regulation and functional involvement in oligodendrocyte differentiation have remained elusive. Here, we report that the surface-bound NG2 proteoglycan can physically bind to PDGF-AA and enhances PDGF receptor alpha (α) activation of downstream signaling. During differentiation stage, NG2 protein is cleaved by A disintegrin and metalloproteinase with thrombospondin motifs type 4 (), which is highly upregulated in differentiating OPCs but gradually downregulated in mature myelinating oligodendrocytes. Genetic ablation of gene impedes NG2 proteolysis, leading to elevated PDGFRα signaling but impaired oligodendrocyte differentiation and axonal myelination in both sexes of mice. Moreover, deficiency also lessens myelin repair in adult brain tissue following Lysophosphatidylcholine-induced demyelination. Thus, could be a potential therapeutic target for enhancing oligodendrocyte differentiation and axonal remyelination in demyelinating diseases. NG2 is selectively expressed in OPCs and downregulated during differentiation stage. To date, the molecular mechanism underlying the progressive removal of NG2 surface proteoglycan in differentiating OPCs has been unknown. In this study, we demonstrate that ADAMTS4 released by differentiating OPCs cleaves surface NG2 proteoglycan, attenuates PDGFRα signaling, and accelerates oligodendrocyte differentiation. In addition, our study also suggests ADAMTS4 as a potential therapeutic target for promoting myelin recovery in demyelinating diseases.
Topics: Male; Female; Mice; Animals; Remyelination; Receptor, Platelet-Derived Growth Factor alpha; Myelin Sheath; Proteoglycans; Oligodendroglia; Cell Differentiation; Demyelinating Diseases
PubMed: 37188512
DOI: 10.1523/JNEUROSCI.2146-22.2023 -
Cellular and Molecular Life Sciences :... Aug 2023Both adipose tissue and skeletal muscle are highly dynamic tissues and interact at the metabolic and hormonal levels in response to internal and external stress, and...
Both adipose tissue and skeletal muscle are highly dynamic tissues and interact at the metabolic and hormonal levels in response to internal and external stress, and they coordinate in maintaining whole-body metabolic homeostasis. In our previous study, we revealed that adipocyte-specific Rnf20 knockout mice (ASKO mice) exhibited lower fat mass but higher lean mass, providing a good model for investigating the adipose-muscle crosstalk and exploring the effect of the adipocyte Rnf20 gene on the physiology and metabolism of skeletal muscle. Here, we confirmed that ASKO mice exhibited the significantly increased body weight and gastrocnemius muscle weight. Fiber-type switching in the soleus muscle of ASKO mice was observed, as evidenced by the increased number of fast-twitch fibers and decreased number of slow-twitch fibers. Serum metabolites with significant alteration in abundance were identified by metabolomic analysis and the elevated lysophosphatidylcholine 16:0 [LysoPC (16:0)] was observed in ASKO mice. In addition, lipidome analysis of gonadal white adipose tissue revealed a significant increase in LysoPCs and LysoPC (16:0) in ASKO mice. Furthermore, knockdown of Rnf20 gene in 3T3-L1 cells significantly increased the secretion of LysoPC, suggesting that LysoPC might be a critical metabolite in the adipose-muscle crosstalk of ASKO mice. Furthermore, in vitro study demonstrated that LysoPC (16:0) could induce the expression of fast-twitch muscle fibers related genes in differentiated C2C12 cells, indicating its potential role in adipose-muscle crosstalk. Taken together, these findings not only expand our understanding of the biological functions of Rnf20 gene in systemic lipid metabolism, but also provide insight into adipose tissue dysfunction-induced physiological alterations in skeletal muscle.
Topics: Animals; Mice; Adipocytes; Adipose Tissue; Lysophosphatidylcholines; Muscle Fibers, Skeletal; Muscle, Skeletal; Muscular Diseases; Obesity; Ubiquitin-Protein Ligases
PubMed: 37555936
DOI: 10.1007/s00018-023-04896-4 -
The Journal of Biological Chemistry Apr 2024Lipids have been previously implicated in the lifecycle of neuroinvasive viruses. However, the role of lipids in programmed cell death and the relationship between...
Lipids have been previously implicated in the lifecycle of neuroinvasive viruses. However, the role of lipids in programmed cell death and the relationship between programmed cell death and lipid droplets (LDs) in neuroinvasive virus infection remains unclear. Here, we found that the infection of neuroinvasive virus, such as rabies virus and encephalomyocarditis virus could enhance the LD formation in N2a cells, and decreasing LDs production by targeting diacylglycerol acyltransferase could suppress viral replication. The lipidomics analysis revealed that arachidonic acid (AA) was significantly increased after reducing LD formation by restricting diacylglycerol acyltransferase, and AA was further demonstrated to induce ferroptosis to inhibit neuroinvasive virus replication. Moreover, lipid peroxidation and viral replication inhibition could be significantly alleviated by a ferroptosis inhibitor, ferrostatin-1, indicating that AA affected neuroinvasive virus replication mainly through inducing ferroptosis. Furthermore, AA was demonstrated to activate the acyl-CoA synthetase long-chain family member 4-lysophosphatidylcholine acyltransferase 3-cytochrome P450 oxidoreductase axis to induce ferroptosis. Our findings highlight novel cross-talks among viral infection, LDs, and ferroptosis for the first time, providing a potential target for antiviral drug development.
Topics: Ferroptosis; Lipid Droplets; Animals; Virus Replication; Mice; Arachidonic Acid; Encephalomyocarditis virus; Diacylglycerol O-Acyltransferase; Lipid Peroxidation; Coenzyme A Ligases; Cell Line, Tumor; Humans
PubMed: 38490434
DOI: 10.1016/j.jbc.2024.107168 -
Protein & Cell Mar 2024Ferroptosis has been recognized as a unique cell death modality driven by excessive lipid peroxidation and unbalanced cellular metabolism. In this study, we established...
Ferroptosis has been recognized as a unique cell death modality driven by excessive lipid peroxidation and unbalanced cellular metabolism. In this study, we established a protein interaction landscape for ferroptosis pathways through proteomic analyses, and identified choline/ethanolamine phosphotransferase 1 (CEPT1) as a lysophosphatidylcholine acyltransferase 3 (LPCAT3)-interacting protein that regulates LPCAT3 protein stability. In contrast to its known role in promoting phospholipid synthesis, we showed that CEPT1 suppresses ferroptosis potentially by interacting with phospholipases and breaking down certain pro-ferroptotic polyunsaturated fatty acid (PUFA)-containing phospholipids. Together, our study reveals a previously unrecognized role of CEPT1 in suppressing ferroptosis.
PubMed: 38430542
DOI: 10.1093/procel/pwae004