key: cord-1016139-xib4udiw
authors: Donoso‐Quezada, Javier; Ayala‐Mar, Sergio; González‐Valdez, José
title: The role of lipids in exosome biology and intercellular communication: Function, analytics and applications
date: 2021-06-11
journal: Traffic
DOI: 10.1111/tra.12803
sha: aad4af594c887b3fcc162309e65571fd7eca6d39
doc_id: 1016139
cord_uid: xib4udiw

Exosomes are extracellular vesicles that in recent years have received special attention for their regulatory functions in numerous biological processes. Recent evidence suggests a correlation between the composition of exosomes in body fluids and the progression of some disorders, such as cancer, diabetes and neurodegenerative diseases. In consequence, numerous studies have been performed to evaluate the composition of these vesicles, aiming to develop new biomarkers for diagnosis and to find novel therapeutic targets. On their part, lipids represent one of the most important components of exosomes, with important structural and regulatory functions during exosome biogenesis, release, targeting and cellular uptake. Therefore, exosome lipidomics has emerged as an innovative discipline for the discovery of novel lipid species with biomedical applications. This review summarizes the current knowledge about exosome lipids and their roles in exosome biology and intercellular communication. Furthermore, it presents the state‐of‐the‐art analytical procedures used in exosome lipidomics while emphasizing how this emerging discipline is providing new insights for future applications of exosome lipids in biomedicine.

The MVBs either fuse with the lysosome for the degradation of the ILVs or reach the cell membrane to release the ILVs as exosomes. 3 Exosomes, like other EVs, are limited by a lipidic membrane, which encapsulates the cargo molecules in an inner aqueous core. In the particular case of exosomes, these cargo molecules are mainly peptides, small proteins and nucleic acids, such as mRNA or miRNA, all of them used by the cell to transmit signals to other cell populations, coordinate biological functions and maintain homeostasis. 4 Despite its wide use in EVs reports, the application of the above-mentioned terminology is misleading in the practice due to the current limitations to isolate a particular type of EVs in a pure form. Therefore, the International Society for Extracellular vesicles on the Minimal Information for Studies of Extracellular Vesicles 2018 (MISEV 2018) suggest the use of alternative terms such as "small EVs" (<200 nm) or "large EVs" (>200 nm). 5 Lately, exosomal proteins and nucleic acids have received particular attention in several studies exploring the biological processes in which they are involved with therapeutic purposes. [6] [7] [8] However, exosomal lipids represent other less-explored bioactive molecules abundantly present in exosomes, not only as part of their structure but also exerting regulatory functions in receptor cells. 9 Figure 1 shows [9] [10] [11] [12] [13] In this sense, recent lipidomic studies over exosomes derived from different cell types describe the lipidic composition of these EVs and propose alterations under pathological conditions to contribute to the current knowledge about the physiology of exosomal lipids. [14] [15] [16] In this context and considering the increased interest in exosomal lipids as regulatory molecules and biomarkers observed during the last years, this review describes the most recent advances in exosome lipidomics and their applications, emphasizing the biological importance of exosomal lipids in producer cells and their regulatory function in receptor cells. We also analyze some critical challenges regarding the currently available methods for exosome lipidomic analysis, and some opportunities and future perspectives about the applications of this promising technology. It is important to note that according to the MISEV 2018, 5 the term "extracellular vesicles" is preferred over exosomes since it is difficult to ensure that a particular subtype of EVs (i.e., exosomes) is present in a sample without contamination with other EVs populations. Therefore, in this review, the term exosome is used only to refer to small EVs (50-150 nm) isolated by the commonly accepted methods (e.g., ultracentrifugation, ultrafiltration, precipitation, etc.), expressing cytosolic or transmembrane proteins specific for EVs (e.g., ALIX, syntenin, CD63, etc.), and reported as exosomes by the authors of the works cited in this review. Otherwise, the term EVs is used instead of exosomes.

F I G U R E 1 The number of publications between 2000 and 2019 in PubMed related to exosome genomics, proteomics, or lipidomics. The search terms were "exosome" and "proteomic", "proteomics" or "proteome" (green); "exosome" and "genomics", "genomic" or "genome" (red); "exosome" and "lipidomics", "lipidomic" or "lipidome" (blue) 2 | EXOSOME LIPID COMPOSITION Lipids are essential elements found in all cell types and abundantly distributed in EVs. Sphingomyelin, phospholipids, ganglioside GM3 and cholesterol are lipid classes commonly found in cell membranes and consequently in exosomes. 14 However, the relative abundance of these lipids in exosomal membranes may vary depending on the producer cell type, 17 the physiological stage of the producer cell, 16 and the fate and function of the exosome. 18 In this regard, several studies revealed that exosomes produced under different conditions modify their lipid and metabolite composition to modulate their biological function. For example, in vitro studies revealed that PC3 cells co-cultured with the ether lipid precursor hexadecylglycerol secret exosomes enriched in ether lipids and with different protein composition, demonstrating the impact of external stimuli to modify the lipidic and nonlipidic exosome composition. 19 Similar results were obtained with Huh7 cells co-cultured with palmitate and LPC, which resulted in an enhanced release of EVs with pro-inflammatory activity. 20 Furthermore, it has also been found that exosomes derived from mesenchymal stem cells (MSC) cultured under priming conditions are packaged with lipids and other metabolites associated with the immunomodulatory properties of MSC, including macrophage polarization. 21 The lipidic composition of exosomes derived from different sources and the enrichment of some lipid classes concerning producer cells has been extensively reported in several works. 17, 22, 23 In this sense, B-lymphocyte-derived exosomes are enriched in cholesterol (CHOL) up to 3 times more when compared to the cell membrane. 24 Apparently, CHOL starts to be accumulated in MVBs and this process appears to be essential for the formation of intraluminal vesicles, the precursors of exosomes. 22 Similarly, sphingomyelin (SM) enrichment in exosome membranes has caused these EVs to be considered as a new type of SM domain. This enrichment could originate from plasma membrane lipid rafts, and also at the expense of phosphatidylcholine (PC) through the activity of the sphingomyelin synthase. 22 Moreover, lipidomic studies in PC3 cells-derived exosomes confirmed that the exosomal membrane is a highly ordered structure enriched in glycosphingolipids, which confers the exosomes the demonstrated stability they present in extracellular environments. 17 This ordered distribution of lipids in the exosomal membrane could be responsible for several interactions during exosome formation, release and delivery to receptor cells, as discussed in the following subsections. It is important to note that the lipid distribution into exosomes and other EVs is a dynamic process that responds to several factors. For instance, significant variations in the lipidic composition of reticulocyte-derived exosomes were found in response to the physiological changes in the cell during the maturation to erythrocytes, demonstrating that the sorting of lipids for exosome biogenesis adapts to the cell requirements. 16 The distribution of lipids in the two leaflets of the lipid bilayer appears to be asymmetrical in the exosome membrane, with SM typically found in the outer leaflet and phosphatidylserine (PS) species in the inner leaflet. 25 However, it has been reported that PS is externalized in apoptotic and malignant cells, acting as an "eat me" signal for macrophages in the immune system. 26 Thus, exosomes and other EVs secreted by malignant cells also expose PS at the outer leaflet, opening novel perspectives for their potential use as exosomal biomarkers for cancer diagnosis. 27 In this context, a PS-targeted microfluidic device has been developed to isolate cancer-derived exosomes from plasma, achieving 90% capture efficiency for cancer cell exosomes, and resulting in a promising tool to explore the role of exosomes and exosomal lipids in cancer progression. 28 Conversely, other studies affirm that microvesicles and exosomes lack the membrane asymmetry found in producer cells because of the presence of a phospholipid scramblase in the exosome membrane, evidenced by the presence of PS and phosphatidylethanolamine (PE) in the outer leaflet. 29 Besides, recent lipidomic studies revealed that some lipids are exclusively or preferentially distributed to certain types of EVs, suggesting the existence of various highly controlled processes involved in the biogenesis of EVs and cargo packaging in which lipids play an indispensable role. 30 Some relevant studies regarding this differential distribution of lipids in EV subpopulations are presented in Table 1 . It is also important to mention as well that the advances in purification methods have allowed the isolation of a novel and smaller vesicle that has been named "exomeres" ($35 nm). 15 Despite structural similarities with exosomes, exomeres seem to differ in lipidic composition, presenting higher content of triglyceride (TG), ceramide (Cer) and lysophosphatidylglycerol (LPG) when compared to exosomes, as shown in Table 1 . Hence, this differential lipidic composition of EVs allows lipids to be considered important markers to assess the purity of exosome preparations. 31 Furthermore, recent studies reported that the lipid alterations in EVs isolated from pleural effusion of patients with pulmonary tuberculosis and lung cancer were different in small EVs regarding large EVs. 32 These findings suggest that the differential distribution of lipids in EVs subpopulations could be used to identify more sensitive biomarkers contained in a particular type of EVs.

Exosome biogenesis is a high-regulated process in which the endosomal sorting complex required for the transport (ESCRT) plays an essential role, recruiting exosomal cargo components and inducing the formation of ILVs from the endosomal membrane. 30 However, more recently, novel ESCRT-independent mechanisms have received attention due to their capacity to induce EV formation in the absence of ESCRT machinery, one of them is the denominated lipid-driven mechanism. 38 Moreover, the enrichment of several lipid classes in exosomes and the differential lipidic composition of these EVs under different physiological conditions raises one question: what is the role of these lipids in the biology of exosomes? To answer this interrogation, this section focuses on the most relevant processes involved in exosome biogenesis in which lipids seem to play regulatory functions. Some important findings in this field are presented in Table 2 . Moreover, we present a discussion about some possible future applications of this biogenic role of lipids in exosome-related technologies.

The ESCRT machinery plays a fundamental role in the formation of MVBs and the packaging of cargo components into exosomes. 30 In vitro studies revealed that the ESCRT machinery induces the formation of ordered membrane microdomains in a CHOL-dependent manner, suggesting that CHOL content within endosomal membranes may provide adequate conditions for exosome formation, as shown in monocytes. 40 In this sense, the use of statins was reported to reduce the exosome release in BEAS-2B and THP-1 cells owing to its cholesterol-lowering effect, 41 opening novel perspectives regarding the use of statins as therapeutic agents to control exosome production in target cells.

Ceramide is one of the most important lipids in exosome biogenesis because of its apparent capacity to trigger ESCRT-independent processes and induce spontaneous membrane invagination ( Figure 2 ). 42 Ceramide is synthesized from SM after removal of a phosphocholine moiety by sphingomyelinases, and the spontaneous budding of ceramide-containing membranes is attributed to its cone-shaped structure, which facilitates the negative curvature of the membrane. 38 In vitro experiments revealed the capacity of sphingomyelinases by themselves to induce membrane budding and vesicle formation in synthetic membranes containing SM after ceramide synthesis. 43 Therefore, the use of exogenous sphingomyelinases may represent an alternative to enhance the in vitro production of exosomes from cell lines of interest for scientific or therapeutic purposes.

Similarly, ESCRT-independent cargo sorting in exosomes occurs in the cells through the constitutive activation of inhibitory G proteincoupled sphingosine 1-phosphate (S1P) receptors by a constant supply of S1P, representing another lipid-regulated mechanism for the maturation of exosomal MVBs. 44 T A B L E 2 Role of some relevant lipids during exosome biogenesis

Cholesterol EVs formation, transport and release.

• Provide adequate membrane conditions for budding by maintaining the equilibrium between liquid-ordered and disordered domains. • Interact with ORP1L and control the movement of endosomes along microtubules. • Induce the fusion of MVBs with the cell membrane. 39, 51 Ceramide

EVs formation • Induce the negative curvature of the membrane. 38 Diacylglycerol EVs formation • Recruit soluble proteins in the cell membrane.

• Interact with cytoskeletal proteins. 52 Ether lipids EVs release • The fusion of MVBs with the cell membrane to release exosomes. 19 Phosphatidic acid EVs formation • Responsible for several protein-lipid interactions.

• Interaction with syntenin to recruit syndecan, CD63, and ALIX in the budding site. • Induce membrane negative curvature. 45, 46 Phosphatidylinositol 3-phosphate EVs formation and cargo sorting.

• Binding with ESCRT-0 to recruit ESCRT-I, -II and -III machinery in the membrane. • Interaction with Hrs protein to begin the cargo sorting into endosomes. 53, 54 Bis(monoacyl-glycero) phosphate EVs formation and release.

• Interaction with ALIX and HSP-70.

• Fusogenic properties. 55, 56 Cardiolipin EVs stabilization • Induce negative membrane curvature.

• Stabilize the small structure of the exosomes. 37 Phosphatidylinositol-3,5-biphosphate

EVs release • Regulation of lysosomal degradation of MVBs by fusion with lysosomes. 57 Sphingosine 1-phosphate Cargo sorting • Interaction with inhibitory G protein-coupled S1P receptors in MVB membrane. 44 

Like ceramide, the phosphatidic acid (PA) is the simplest phospholipid with a small headgroup and cone-shaped structure that confers PA the capacity to induce spontaneous negative curvature in lipidic membranes ( Figure 2 ). 45, 46 Moreover, the physicochemical properties of PA are given in part by its headgroup, allowing protein-lipid interactions between PA and the lysine and arginine residues of proteins. 47 Hence, PA is reported to interact with syntenin triggering the recruitment of syndecan, CD63 and ALIX in the membrane, stimulating the budding process of nascent ILVs. 48 Furthermore, it is proposed that sphingomyelinases interact with PA to enhance ceramide production and promote the ILVs budding in an ESCRT-independent way. 49 The synthesis of PA in the cells is regulated by the activity of phospholipases, 50 therefore the use of exogenous phospholipases could be explored to increase the production of exosomes in vitro and to support the development of exosome-related technologies. Other phospholipids that appear to play important regulatory functions during exosome biogenesis include phosphatidylinositol 3-phosphate and phosphatidylinositol 3,5-biphosphate, which seem to regulate the EVs formation, release and cargo sorting, as shown in Table 2 .

Exosomes act as nanocarriers of bioactive lipids between cells to regulate specific biological processes. However, their activity is not limited to transport lipids from one cell to another, but also to produce bioactive lipids from other lipidic molecules through the activity of exosomal enzymes packaged into these EVs during their biogenesis. 58 In this sense, this section focuses both on the role of exosomes as lipidic particles as well as functional units for lipid transformation.

Exosomes contain all three A2 phospholipases classes (PLA2); the calcium-dependent PLA2 (cPLA2), the calcium-independent PLA2 (iPLA2), and the secreted PLA2 (sPLA2). These enzymes hydrolyze glycerophospholipids to produce arachidonic acid (AA) and other free fatty acids. 59 AA can be further processed by the 5-lipoxygenase to release a set of oxidized eicosanoids named leukotrienes such as LTB4, involved in the inflammation process, and the F I G U R E 2 Lipids in exosome biogenesis. Membrane domains enriched in cholesterol appear to provide adequate conditions for the recruitment of ESCRT machinery in MVBs. Ceramide and phosphatidic acid are cone-shaped lipids that seem to induce spontaneous curvature of the MVBs membrane in an ESCRT-independent manner. Ceramide is produced from sphingomyelin through the activity of the sphingomyelinases (SMase). On their part, phosphatidic acid is produced from phosphatidylcholine and diacylglycerol through the activity of the phospholipases (PLase) and diacylglycerol kinases (DGK), respectively. Furthermore, phosphatidic acid seems to interact with syndecan to enhance the recruitment of syntenin (Syn), ALIX and the ESCRT machinery angiogenesis-promoting LTC4 and LTD4. 60 Furthermore, the myoblast cells C2C12 exposed to palmitate produced palmitate-enriched exosomes with the capability to induce myoblast proliferation and to alter the expression of genes involved in cell cycle and muscle differentiation. Besides, these exosomes were able to be incorporated in various tissues in vivo, including the pancreas and liver, transferring by this way the deleterious effect of palm oil between muscle cells and other tissues. 68 In the brain, as an organ with one of the highest lipid concentrations, 69 

Advances in mass spectrometry (MS) have made this method the dominating platform in the lipidomic analysis. 83 On its part, nuclear magnetic resonance (NMR) has become a less-used system limited by its lower sensitivity, the presence of overlapping signals, and the low natural abundance of 13 C for 13 CNMR. 84 

The growing interest in lipidomics as a tool for the evaluation of cell homeostasis demands the development of bioinformatic workflows to identify, quantify and study the influence of lipids on metabolism.

However, despite the existence of bioinformatic mechanisms for these purposes, some of them lack simplicity and interconnectivity and are not user-friendly. 103 Thus, the "Lipidomics Informatics for Life-Science" platform has recently provided its lipidomics software tools with integrative and user-friendly web interfaces. These tools include "LipidXplorer" for shotgun lipidomics, 104 "Skyline for Lipidomics" to assemble targeted mass spectrometry methods for complex lipids, 105 "LUX Score" for the quantification of systematic differences in the lipid composition of a lipidome, 106 and "LipidHome", to bridge the gap between theoretically identified lipid molecules and metadata. 107 All these tools have been recently used to identify exosome lipidic biomarkers in pancreatic cancer. 11 A similar bioinformatic platform extensively used to analyze 93% sensitivity and 100% specificity. 10 Similar research in the area includes the use of serum and blood plasma exosome lipids in pancreatic 11 and non-small cell lung cancer diagnosis, 13 as described in detail in Table 3 . 93% sensitivity and 100% specificity by using the combination of the three lipids. 10 Non-small cell lung cancer [121] [122] [123] Since this method for the fractionation of EVs is based on their lipidic composition, future research in this field should focus on the enhancement of the diagnosis properties of exosome lipids after a CTB, AV and STB fractionation (see Table 3 ).

Given the previously mentioned role of exosomes in the pathogenesis of some diseases, several strategies have been proposed to highlight their potential as novel therapeutic targets by inhibiting key aspects in their biology, such as biogenesis, release and cell uptake. 124 These novel methods could be applied in disorders in which exosomes induce a pathological effect (Figure 4 ). For example, in cancer, it has been demonstrated that the amount of circulating EVs is correlated with cancer progression, and with the survival of patients with melanoma. 125 In this case, a therapeutic intervention could be aimed at reducing the load of exosomes in blood by inhibiting their biogenesis or release.

One of the strategies proposed with this aim is the reduction of the endosomal sorting and exosome biogenesis through the inhibition of the sphingomyelinase, the enzyme that synthesizes ceramide from SM. This inhibition can be achieved with the blood-pressure-lowering drug amiloride, which has demonstrated an efficient in vivo reduction of the circulating tumor-derived EVs with the subsequent reduction in tumor growth. 38, 126 Similarly, the biosynthesis of ceramide has also been inhibited using GW4869 and some specific small interfering RNA, reducing exosome release. 127, 128 However, a study in PC3 cells revealed that this interference in exosome biogenesis attained by inhibiting the synthesis of ceramide could be cell-type specific, with lower or no effect in certain cell types. 129 Similar lipid-related molecules acting as therapeutic targets in exosomes include the diacylglycerol kinase α (DAGK α) and PS. In this sense, the inhibition of the DAGKα by the DAGK inhibitor II resulted in a decreased secretion of exosomes in J-HM1-2.2 cells. 130 On their part, PS is a lipid molecule exposed on exosome surface important for cell adhesion. 131 The evidence suggests that blocking PS with diannexin reduces the cellular uptake of exosomes, resulting also in a decreased growth of tumor xenografts in mice. 132, 133 Furthermore, to prevent the exosome-mediated cholesterol accumulation in atheroma-associated cells, anti-PS receptor antibodies were evaluated, resulting in a diminished internalization of exosomes in cells with favorable outcomes. 9 However, therapeutic strategies based on blocking PS should be carefully designed to avoid interference with other physiological functions regulated by PS, such as the clearing of apoptotic cells. 124 In brain astrocytes, it has been found that the amyloid-β (Aβ) peptide stimulates the secretion of exosomes enriched in both ceramide and the ceramide-sensitizer protein PAR-4, with apoptotic effects.

This deleterious effect was suppressed by inhibiting the activity of sphingomyelinase 2. 134 Furthermore, exosomes can also act as Aβ scavengers by sequestering Aβ through the glycosphingolipids on the exosome surface. 135 The inhibition of the sphingomyelinase 2 activity to avoid exosome-induced apoptosis in astrocytes and the Aβ clearance effect of exogenous exosomes in the brain provides novel insights for therapeutic intervention in Alzheimer's disease. [136] [137] [138] The cellular internalization of exosomes derived from glioblastoma cells involves the non-classical, lipid raft-dependent endocytosis negatively regulated by the lipid raft-associated protein caveolin-1 (CAV-1). 139 This study revealed that exosome internalization depends First, standardized methods for sample preparation and storage need to be developed, especially considering the instability of lipids under certain temperatures, 141 pH, 142 or freezing conditions. 143 Besides, conventional exosome isolation methods such as ultracentrifugation, polymer-based precipitation, size exclusion, density gradient centrifugation and immunoaffinity capture, may induce loss of exosome integrity and co-isolation of other non-exosome EVs, disturbing the results of lipidomic analysis. 81 Therefore, the optimization of these traditional methods for lipidomic studies or new exosome isolation systems is required. As an alternative, flow field-flow fractionation has been proposed as a new size-based isolation method with favorable outcomes in exosome lipidomics that needs to be further studied. 144 Improvements in analytical methods to achieve full coverage of lipidomes are also required. Many isomeric/isobaric lipid species precludes the use of the shotgun approach in future lipidomic research.

Therefore, innovative chromatographic separations need to be developed, like those previously proposed using mobile-phase modifier systems. 101 Similarly, migration from HPLC to 2.1 mm UHPLC or microflow LC systems may improve the sample throughput and the quality of the results. 83 The absolute quantification of all lipid species in a lipidome remains a major challenge due to the limited number of commercially available lipid standards. Consequently, it is also necessary to establish a consensus in the field of lipidomics about how much accuracy is required to quantitate individual molecular lipid species. Moreover, structural validation of lipids is essential, especially in those proposed as biomarkers.

In this sense, tandem MS analysis should be needed, as well as sample derivatization methods to validate functional groups. 145 In summary, despite the recent achievements in the field of exosome lipidomics, research in this field is still incipient. Therefore, future comprehensive studies are indispensable to increase the cur- 

Biogenesis of extracellular vesicles (EV): exosomes, microvesicles, retrovirus-like vesicles, and apoptotic bodies

Investigation of endocytic pathways for the internalization of exosome-associated oligomeric alpha-synuclein

Vesicle formation during reticulocyte maturation. Association of plasma membrane activities with released vesicles (exosomes)

Exosomes maintain cellular homeostasis by excreting harmful DNA from cells

Minimal information for studies of extracellular vesicles 2018 (MISEV2018): a position statement of the International Society for Extracellular Vesicles and update of the MISEV2014 guidelines

The potential of exosomes as theragnostics in various clinical situations

The function and therapeutic use of exosomes in bacterial infections

Exosome as a vehicle for delivery of membrane protein therapeutics, PH20, for enhanced tumor penetration and antitumor efficacy

T cell exosomes induce cholesterol accumulation in human monocytes via phosphatidylserine receptor

Molecular lipid species in urinary exosomes as potential prostate cancer biomarkers

Metabolomics identifies serum and exosomes metabolite markers of pancreatic cancer

Urinary exosomal lipidomics reveals markers for diabetic nephropathy

Exosomal lipids for classifying early and late stage non-small cell lung cancer

Proteomics, transcriptomics and lipidomics of exosomes and ectosomes

Identification of distinct nanoparticles and subsets of extracellular vesicles by asymmetric flow field-flow fractionation

Proteolipidic composition of exosomes changes during reticulocyte maturation

Molecular lipidomics of exosomes released by PC-3 prostate cancer cells

Exosomal lipids impact notch signaling and induce death of human pancreatic Tumoral SOJ-6 cells

The ether lipid precursor hexadecylglycerol stimulates the release and changes the composition of exosomes derived from PC-3 cells

Lipid-induced signaling causes release of inflammatory extracellular vesicles from hepatocytes

Primed mesenchymal stem cells package exosomes with metabolites associated with immunomodulation

Exosome lipidomics unravels lipid sorting at the level of multivesicular bodies. Biochimie

Lipidomic characterization of exosomes isolated from human plasma using various mass spectrometry techniques

Proteomic and biochemical analyses of human B cell-derived exosomes: potential implications for their function and multivesicular body formation

Caspase-mediated cleavage of phospholipid flippase for apoptotic phosphatidylserine exposure

Identification of Tim4 as a phosphatidylserine receptor

Detection of phosphatidylserine-positive exosomes as a diagnostic marker for ovarian malignancies: a proof of concept study

Isolation and profiling of circulating tumor-associated exosomes using extracellular vesicular lipid-protein binding affinity based microfluidic device

Mast cell-and dendritic cell-derived exosomes display a specific lipid composition and an unusual membrane organization

Analysis of ESCRT functions in exosome biogenesis, composition and secretion s the heterogeneity of extracellular vesicles

Exosomal lipid composition and the role of ether lipids and phosphoinositides in exosome biology

Metabolic characteristics of large and small extracellular vesicles from pleural effusion reveal biomarker candidates for the diagnosis of tuberculosis and malignancy

Characterization of exosome subpopulations from RBL-2H3 cells using fluorescent lipids

Discrimination of urinary exosomes from microvesicles by lipidomics using thin layer liquid chromatography (TLC) coupled with MALDI-TOF mass spectrometry

Membrane lipids define small extracellular vesicle subtypes secreted by mesenchymal stromal cells

Characterisation of adipocyte-derived extracellular vesicle subtypes identifies distinct protein and lipid signatures for large and small extracellular vesicles

High-resolution proteomic and lipidomic analysis of exosomes and microvesicles from different cell sources

Ceramide triggers budding of exosome vesicles into multivesicular endosomes

Endosomal sorting complex required for transport (ESCRT) complexes induce phase-separated microdomains in supported lipid bilayers

Cholesterol impairs hepatocyte lysosomal function causing M1 polarization of macrophages via exosomal miR-122-5p

Simvastatin mediates inhibition of exosome synthesis, localization and secretion via multicomponent interventions

Multivesicular endosome biogenesis in the absence of ESCRTs

Vectorial budding of vesicles by asymmetrical enzymatic formation of ceramide in giant liposomes

Ongoing activation of sphingosine 1-phosphate receptors mediates maturation of exosomal multivesicular endosomes

Spontaneous curvature of phosphatidic acid and lysophosphatidic acid

Modulation of membrane curvature by phosphatidic acid and lysophosphatidic acid

Protein-phospholipid interaction motifs: a focus on phosphatidic acid

Syntenin-ALIX exosome biogenesis and budding into multivesicular bodies are controlled by ARF6 and PLD2

Identification of novel anionic phospholipid binding domains in neutral sphingomyelinase 2 with selective binding preference

Phosphatidic acid and cardiolipin coordinate mitochondrial dynamics

Cholesterol sensor ORP1L contacts the ER protein VAP to control Rab7-RILP-p150Glued and late endosome positioning

How proteins move lipids and lipids move proteins

Phosphatidylinositol-3-phosphate regulates sorting and processing of amyloid precursor protein through the endosomal system

Class III phosphatidylinositol 3-kinase and its catalytic product PtdIns3P in regulation of endocytic membrane traffic

Hsp70 stabilizes lysosomes and reverts Niemann-pick disease-associated lysosomal pathology

Role of LBPA and Alix in multivesicular liposome formation and endosome organization

PIKfyve inhibition increases exosome release and induces secretory autophagy

Lipids in exosome biology

Exosomes account for vesicle-mediated transcellular transport of activatable phospholipases and prostaglandins

Transcellular biosynthesis of cysteinyl leukotrienes in vivo during mouse peritoneal inflammation

Lipid sensing by mTOR complexes via de novo synthesis of phosphatidic acid

T cell chemotaxis to lysophosphatidylcholine through the G2A receptor

Secretory phospholipase A2 induces dendritic cell maturation

Phospholipase D activity facilitates Ca2 +-induced aggregation and fusion of complex liposomes

Separation and characterization of late endosomal membrane domains

Unique lipid signatures of extracellular vesicles from the airways of asthmatics

Exosomal transfer of mitochondria from airway myeloid-derived regulatory cells to T cells

Exosomes participate in the alteration of muscle homeostasis during lipid-induced insulin resistance in mice

Sphingolipids: membrane microdomains in brain development, function and neurological diseases

Enhanced release of acid sphingomyelinase-enriched exosomes generates a lipidomics signature in CSF of multiple sclerosis patients

Direct and potent regulation of γ-secretase by its lipid microenvironment

Exosomal lipids induce human pancreatic tumoral MiaPaCa-2 cells resistance through the CXCR4-SDF-1α signaling axis

An endothelial-to-adipocyte extracellular vesicle Axis governed by metabolic state

A lipase-independent pathway of lipid release and immune modulation by adipocytes

Lipotoxic stress alters the membrane lipid profile of extracellular vesicles released by Huh-7 hepatocarcinoma cells

Hepatocyte-derived Lipotoxic extracellular vesicle sphingosine 1-phosphate induces macrophage chemotaxis

Transcellular activation of platelets and endothelial cells by bioactive lipids in platelet microparticles

Induction of myeloid-derived suppressor cells by tumor exosomes

Enterobacteria-secreted particles induce production of exosome-like S1P-containing particles by intestinal epithelium to drive Th17-mediated tumorigenesis

Schistosoma mansoni-derived lipids in extracellular vesicles: potential agonists for eosinophillic tissue repair

Analytical challenges and recent advances in mass spectrometry based lipidomics

Comprehensive Mass Spectrometry of Lipids. Hoboken

Toward merging untargeted and targeted methods in mass spectrometry-based metabolomics and lipidomics

Metabonomic models of human pancreatic cancer using 1D proton NMR spectra of lipids in plasma

Analysis of in vitro oxidized human LDL phospholipids by solid-phase extraction and micellar electrokinetic capillary chromatography

Phospholipid composition of postmortem schizophrenic brain by 31 P NMR spectroscopy

Diagnosing inborn errors of lipid metabolism with proton nuclear magnetic resonance spectroscopy

Evaluation of established coronary heart disease on the basis of HDL and non-HDL NMR lipid profiling

Detection of adulteration in Iranian olive oils using instrumental (GC, NMR, DSC) methods

Using 1H and 13C NMR techniques and artificial neural networks to detect the adulteration of olive oil with hazelnut oil

A simple methodology for the determination of fatty acid composition in edible oils through 1H NMR spectroscopy

Complementary precursor ion and neutral loss scan mode tandem mass spectrometry for the analysis of glycerophosphatidylethanolamine lipids from whole rat retina

An introduction to quadrupole-time-of-flight mass spectrometry

Collision-induced dissociation pathways of yeast sphingolipids and their molecular profiling in total lipid extracts: a study by quadrupole TOF and linear ion trap-orbitrap mass spectrometry

Rapid and comprehensive 'shotgun' lipidome profiling of colorectal cancer cell derived exosomes

Lipidomics: prospects from a technological perspective

Recent developments in liquid chromatography-mass spectrometry and related techniques

Widely-targeted quantitative lipidomics method by supercritical fluid chromatography triple quadrupole mass spectrometry

A hyphenated microLC-Q-TOF-MS platform for exosomal lipidomics investigations: application to RCC urinary exosomes

Investigation of lipidomic perturbations in oxidatively stressed subcellular organelles and exosomes by asymmetrical flow field-flow fractionation and nanoflow ultrahigh performance liquid chromatography-tandem mass spectrometry

Increasing lipidomic coverage by selecting optimal mobile-phase modifiers in LC-MS of blood plasma

Accelerating lipidomic method development through in silico simulation

Lipidomics informatics for life-science

Lipidxplorer: a software for consensual crossplatform lipidomics

Adaptation of skyline for targeted lipidomics

The LUX score: a metric for Lipidome homology

LipidHome: a database of theoretical lipids optimized for high throughput mass spectrometry lipidomics

LIPID MAPS online tools for lipid research

LipidFinder: a computational workflow for discovery of lipids identifies eicosanoid-phosphoinositides in platelets

LipidFinder on LIPID MAPS: peak filtering, MS searching and statistical analysis for lipidomics

Untargeted multi-omic analysis of colorectal cancer-specific exosomes reveals joint pathways of colorectal cancer in both clinical samples and cell culture

Membrane lipid binding molecules for the isolation of bona fide extracellular vesicle types and associated biomarkers in liquid biopsy

High-abundance polypeptides of the human plasma proteome comprising the top 4 logs of polypeptide abundance

Low-density lipoprotein mimics blood plasmaderived exosomes and microvesicles during isolation and detection

Analysis of the regenerative capacity of human serum exosomes after a simple multistep separation from lipoproteins

A novel method of high-purity extracellular vesicle enrichment from microliter-scale human serum for proteomic analysis. Electrophoresis

Lipidomic analysis of urinary exosomes from hereditary α-tryptasemia patients and healthy volunteers

Circulating exosomes are strongly involved in SARS-CoV-2 infection

Omics-driven systems interrogation of metabolic dysregulation in COVID-19 pathogenesis

MSC secretes at least 3 EV types each with a unique permutation of membrane lipid, protein and RNA

Plasma biomarker discovery in preeclampsia using a novel differential isolation technology for circulating extracellular vesicles

EV-associated MMP9 in highgrade serous ovarian cancer is preferentially localized to Annexin V-binding EVs

A preliminary investigation of circulating extracellular vesicles and biomarker discovery associated with treatment response in head and neck squamous cell carcinoma

Extracellular vesicles: biology and emerging therapeutic opportunities

High levels of exosomes expressing CD63 and caveolin-1 in plasma of melanoma patients

Acid sphingomyelinase activity triggers microparticle release from glial cells

Secretory mechanisms and intercellular transfer of microRNAs in living cells

Blockade of exosome generation with GW4869 dampens the sepsis-induced inflammation and cardiac dysfunction

Regulation of exosome release by glycosphingolipids and flotillins

Diacylglycerol kinase α regulates the formation and polarisation of mature multivesicular bodies involved in the secretion of Fas ligand-containing exosomes in T lymphocytes

Diversification of TAM receptor tyrosine kinase function

Endothelial expression of autocrine VEGF upon the uptake of tumor-derived microvesicles containing oncogenic EGFR

Tumor-derived microvesicles modulate the establishment of metastatic melanoma in a phosphatidylserine-dependent manner

Astrocytes secrete exosomes enriched with proapoptotic ceramide and prostate apoptosis response 4 (PAR-4): potential mechanism of apoptosis induction in Alzheimer disease (AD)

A potential function for neuronal exosomes: sequestering intracerebral amyloid-β peptide

ATP13A2/PARK9 regulates secretion of exosomes and -synuclein

Parkinson's disease-linked human PARK9/ATP13A2 maintains zinc homeostasis and promotes α-Synuclein externalization via exosomes

Exosomes of BV-2 cells induced by alpha-synuclein: important mediator of neurodegeneration in PD

Exosome uptake depends on ERK1/2-heat shock protein 27 signaling and lipid raftmediated endocytosis negatively regulated by caveolin-1

Curcumin stimulates exosome/microvesicle release in an in vitro model of intracellular lipid accumulation by increasing ceramide synthesis

High-throughput quantification of lysophosphatidylcholine by electrospray ionization tandem mass spectrometry

High-throughput analysis of sphingosine 1-phosphate, sphinganine 1-phosphate, and lysophosphatidic acid in plasma samples by liquid chromatography: tandem mass spectrometry

Comprehensive approach to the quantitative analysis of mitochondrial phospholipids by HPLC-MS

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The authors would like to thank the School of Engineering and Science 

The authors declare no conflict of interest.

The peer review history for this article is available at https://publons. com/publon/10.1111/tra.12803.

Javier Donoso-Quezada https://orcid.org/0000-0003-2225-3116José Gonz alez-Valdez https://orcid.org/0000-0001-6734-8245