Cytokine-induced release of ceramide-enriched exosomes as a mediator of cell death signaling in an oligodendroglioma cell line

Starting points for the development of new targeted therapies for glioblastoma multiforme

Glioblastoma multiforme (GBM) is one of the most aggressive and lethal brain tumors, characterized by rapid growth, invasiveness, and resistance to standard therapies, including surgery, chemotherapy, and radiotherapy. Despite advances in treatment, GBM remains highly resistant due to its complex molecular mechanisms, including angiogenesis, invasion, immune modulation, and lipid metabolism dysregulation. This review explores recent breakthroughs in targeted therapies, focusing on innovative drug carriers such as nanoparticles and liposomes, and their potential to overcome GBM's chemo- and radioresistant phenotypes. We also discuss the molecular pathways involved in GBM progression and the latest therapeutic strategies, including immunotherapy and precision medicine approaches, which hold promise for improving clinical outcomes. The review highlights the importance of understanding GBM's genetic and molecular heterogeneity to develop more effective, personalized treatment protocols aimed at increasing survival rates and enhancing the quality of life for GBM patients.

Variant rs4149584 (R92Q) of the TNFRSF1A gene in patients with familial multiple sclerosis

INTRODUCTION

Genomic studies have identified numerous genetic variants associated with susceptibility to multiple sclerosis (MS); however, each one explains only a small percentage of the risk of developing the disease. These variants are located in genes involved in specific pathways, which supports the hypothesis that the risk of developing MS may be linked to alterations in these pathways, rather than in specific genes. We analyzed the role of the TNFRSF1A gene, which encodes one of the TNF-α receptors involved in a signaling pathway previously linked to autoimmune disease.

METHODS

We included 138 individuals from 23 families including at least 2 members with MS, and analyzed the presence of exonic variants of TNFRSF1A through whole-exome sequencing. We also conducted a functional study to analyze the pathogenic mechanism of variant rs4149584 (-g.6442643C > G, NM_001065.4:c.362 G > A, R92Q) by plasmid transfection into human oligodendroglioma (HOG) cells, which behave like oligodendrocyte lineage cells; protein labeling was used to locate the protein within cells. We also analyzed the ability of transfected HOG cells to proliferate and differentiate into oligodendrocytes.

RESULTS

Variant rs4149584 was found in 2 patients with MS (3.85%), one patient with another autoimmune disease (7.6%), and in 5 unaffected individuals (7.46%). The 2 patients with MS and variant rs4149584 were homozygous carriers and belonged to the same family, whereas the remaining individuals presented the variant in heterozygosis. The study of HOG cells transfected with the mutation showed that the protein does not reach the cell membrane, but rather accumulates in the cytoplasm, particularly in the endoplasmic reticulum and near the nucleus; this suggests that, in the cells presenting the mutation, TNFRSF1 does not act as a transmembrane protein, which may alter its signaling pathway. The study of cell proliferation and differentiation found that transfected cells continue to be able to differentiate into oligodendrocytes and are probably still capable of producing myelin, although they present a lower rate of proliferation than wild-type cells.

CONCLUSIONS

Variant rs4149584 is associated with risk of developing MS. We analyzed its functional role in oligodendrocyte lineage cells and found an association with MS in homozygous carriers. However, the associated molecular alterations do not influence the differentiation into oligodendrocytes; we were therefore unable to confirm whether this variant alone is pathogenic in MS, at least in heterozygosis.

Should We Consider Neurodegeneration by Itself or in a Triangulation with Neuroinflammation and Demyelination? The Example of Multiple Sclerosis and Beyond

Neurodegeneration is preeminent in many neurological diseases, and still a major burden we fail to manage in patient's care. Its pathogenesis is complicated, intricate, and far from being completely understood. Taking multiple sclerosis as an example, we propose that neurodegeneration is neither a cause nor a consequence by itself. Mitochondrial dysfunction, leading to energy deficiency and ion imbalance, plays a key role in neurodegeneration, and is partly caused by the oxidative stress generated by microglia and astrocytes. Nodal and paranodal disruption, with or without myelin alteration, is further involved. Myelin loss exposes the axons directly to the inflammatory and oxidative environment. Moreover, oligodendrocytes provide a singular metabolic and trophic support to axons, but do not emerge unscathed from the pathological events, by primary myelin defects and cell apoptosis or secondary to neuroinflammation or axonal damage. Hereby, trophic failure might be an overlooked contributor to neurodegeneration. Thus, a complex interplay between neuroinflammation, demyelination, and neurodegeneration, wherein each is primarily and secondarily involved, might offer a more comprehensive understanding of the pathogenesis and help establishing novel therapeutic strategies for many neurological diseases and beyond.

The Yin and Yang of Microglia-Derived Extracellular Vesicles in CNS Injury and Diseases

Microglia, the resident immune cells of the central nervous system (CNS), play a crucial role in maintaining neural homeostasis but can also contribute to disease and injury when this state is disrupted or conversely play a pivotal role in neurorepair. One way that microglia exert their effects is through the secretion of small vesicles, microglia-derived exosomes (MGEVs). Exosomes facilitate intercellular communication through transported cargoes of proteins, lipids, RNA, and other bioactive molecules that can alter the behavior of the cells that internalize them. Under normal physiological conditions, MGEVs are essential to homeostasis, whereas the dysregulation of their production and/or alterations in their cargoes have been implicated in the pathogenesis of numerous neurodegenerative diseases, including Alzheimer's disease (AD), Parkinson's disease (PD), multiple sclerosis (MS), spinal cord injury (SCI), and traumatic brain injury (TBI). In contrast, MGEVs may also offer therapeutic potential by reversing inflammation or being amenable to engineering for the delivery of beneficial biologics or drugs. The effects of MGEVs are determined by the phenotypic state of the parent microglia. Exosomes from anti-inflammatory or pro-regenerative microglia support neurorepair and cell survival by delivering neurotrophic factors, anti-inflammatory mediators, and molecular chaperones. Further, MGEVs can also deliver components like mitochondrial DNA (mtDNA) and proteins to damaged neurons to enhance cellular metabolism and resilience. MGEVs derived from pro-inflammatory microglia can have detrimental effects on neural health. Their cargo often contains pro-inflammatory cytokines, molecules involved in oxidative stress, and neurotoxic proteins, which can exacerbate neuroinflammation, contribute to neuronal damage, and impair synaptic function, hindering neurorepair processes. The role of MGEVs in neurodegeneration and injury-whether beneficial or harmful-largely depends on how they modulate inflammation through the pro- and anti-inflammatory factors in their cargo, including cytokines and microRNAs. In addition, through the propagation of pathological proteins, such as amyloid-beta and alpha-synuclein, MGEVs can also contribute to disease progression in disorders such as AD and PD, or by the transfer of apoptotic or necrotic factors, they can induce neuron toxicity or trigger glial scarring during neurological injury. In this review, we have provided a comprehensive and up-to-date understanding of the molecular mechanisms underlying the multifaceted role of MGEVs in neurological injury and disease. In particular, the role that specific exosome cargoes play in various pathological conditions, either in disease progression or recovery, will be discussed. The therapeutic potential of MGEVs has been highlighted including potential engineering methodologies that have been employed to alter their cargoes or cell-selective targeting. Understanding the factors that influence the balance between beneficial and detrimental exosome signaling in the CNS is crucial for developing new therapeutic strategies for neurodegenerative diseases and neurotrauma.

Exosome Content-Mediated Signaling Pathways in Multiple Sclerosis

Exosomes are small extracellular vesicles with a complex lipid-bilayer surface and 30-150 nm diameter. These vesicles play a critical role in intercellular signaling networks during physiopathological processes through data trafficking and cell reprogramming. It has been demonstrated that exosomes are involved in a variety of central nervous system (CNS) disorders such as multiple sclerosis (MS). Exosome mediators' cell-to-cell communication is possibly by delivering their contents such as proteins, RNAs (coding and non-coding), DNAs (mitochondrial and genomic), and transposable elements to the target cells. Exosomal microRNAs (miRNAs) differ in their expression patterns in MS disease, thereby providing novel diagnostic and prognostic biomarkers and therapeutic options for better treatment of MS disease. Furthermore, these microvesicles are non-immunogenic and non-toxic therapeutic tools for transferring miRNAs across the blood-brain barrier (BBB). Collectively, exosomes could be used as novel drug delivery devices for the treatment of MS patients. This review summarized research regarding the exosomes from serum, plasma, PBMC, and other cells in MS patients and experimental models. We also provide a critical view of exosome content-mediated signaling pathways in MS, including TNF-α, TGF-β, NF-κB, and Wnt pathways. The use of exosomes as a therapeutic potential in MS has also been discussed.

Potential therapeutic and diagnostic approaches of exosomes in multiple sclerosis pathophysiology

Exosomes are bilayer lipid vesicles that are released by cells and contain proteins, nucleic acids, and lipids. They can be internalized by other cells, inducing inflammatory responses and instigating toxicities in the recipient cells. Exosomes can also serve as therapeutic vehicles by transporting protective cargo to maintain homeostasis. Multiple studies have shown that exosomes can initiate and participate in the regulation of neuroinflammation, improve neurogenesis, and are closely related to the pathogenesis of central nervous system (CNS) diseases, including multiple sclerosis (MS). Exosomes can be secreted by both neurons and glial cells in the CNS, and their contents change with disease occurrence. Due to their ability to penetrate the blood-brain barrier and their stability in peripheral fluids, exosomes are attractive biomarkers of CNS diseases. In recent years, exosomes have emerged as potential therapeutic agents for CNS diseases, including MS. However, the molecular pathways in the pathogenesis of MS are still unknown, and further research is needed to fully understand the role of exosomes in the occurrence or improvement of MS disease. Thereby, in this review, we intend to provide a more complete understanding of the pathways in which exosomes are involved and affect the occurrence or improvement of MS disease.

Sphingolipid-Induced Bone Regulation and Its Emerging Role in Dysfunction Due to Disease and Infection

The human skeleton is a metabolically active system that is constantly regenerating via the tightly regulated and highly coordinated processes of bone resorption and formation. Emerging evidence reveals fascinating new insights into the role of sphingolipids, including sphingomyelin, sphingosine, ceramide, and sphingosine-1-phosphate, in bone homeostasis. Sphingolipids are a major class of highly bioactive lipids able to activate distinct protein targets including, lipases, phosphatases, and kinases, thereby conferring distinct cellular functions beyond energy metabolism. Lipids are known to contribute to the progression of chronic inflammation, and notably, an increase in bone marrow adiposity parallel to elevated bone loss is observed in most pathological bone conditions, including aging, rheumatoid arthritis, osteoarthritis, and osteomyelitis. Of the numerous classes of lipids that form, sphingolipids are considered among the most deleterious. This review highlights the important primary role of sphingolipids in bone homeostasis and how dysregulation of these bioactive metabolites appears central to many chronic bone-related diseases. Further, their contribution to the invasion, virulence, and colonization of both viral and bacterial host cell infections is also discussed. Many unmet clinical needs remain, and data to date suggest the future use of sphingolipid-targeted therapy to regulate bone dysfunction due to a variety of diseases or infection are highly promising. However, deciphering the biochemical and molecular mechanisms of this diverse and extremely complex sphingolipidome, both in terms of bone health and disease, is considered the next frontier in the field.

Diagnostic and therapeutic value of EVs in lungs diseases and inflammation

Extracellular vesicles (EVs) are membrane-derived messengers which have been playing an important role in the inflammation and pathogenesis of lung diseases. EVs contain varieties of DNA, RNA, and membrane receptors through which they work as a delivery system for bioactive molecules as well as intracellular communicators. EV signaling mediates tumor progression and metastasis. EVs are linked with many diseases and perform a diagnostic role in lung injury and inflammation so are used to diagnose the severity of diseases. EVs containing a variety of biomolecules communicate with the recipient cells during pathophysiological mechanisms thereby acquiring the attention of clinicians toward the diagnostic and therapeutic potential of EVs in different lung diseases. In this review, we summarize the role of EVs in inflammation with an emphasis on their potential as a novel candidate in the diagnostics and therapeutics of chronic obstructive pulmonary disease, asthma, and sarcoidosis.

Lipid oxidation dysregulation: an emerging player in the pathophysiology of sepsis

Sepsis is a life-threatening organ dysfunction caused by abnormal host response to infection. Millions of people are affected annually worldwide. Derangement of the inflammatory response is crucial in sepsis pathogenesis. However, metabolic, coagulation, and thermoregulatory alterations also occur in patients with sepsis. Fatty acid mobilization and oxidation changes may assume the role of a protagonist in sepsis pathogenesis. Lipid oxidation and free fatty acids (FFAs) are potentially valuable markers for sepsis diagnosis and prognosis. Herein, we discuss inflammatory and metabolic dysfunction during sepsis, focusing on fatty acid oxidation (FAO) alterations in the liver and muscle (skeletal and cardiac) and their implications in sepsis development.

Plasma metabolomics of oral squamous cell carcinomas based on NMR and MS approaches provides biomarker identification and survival prediction

Metabolomics has proven to be an important omics approach to understand the molecular pathways underlying the tumour phenotype and to identify new clinically useful markers. The literature on cancer has illustrated the potential of this approach as a diagnostic and prognostic tool. The present study aimed to analyse the plasma metabolic profile of patients with oral squamous cell carcinoma (OSCC) and controls and to compare patients with metastatic and primary tumours at different stages and subsites using nuclear magnetic resonance and mass spectrometry. To our knowledge, this is the only report that compared patients at different stages and subsites and replicates collected in diverse institutions at different times using these methodologies. Our results showed a plasma metabolic OSCC profile suggestive of abnormal ketogenesis, lipogenesis and energy metabolism, which is already present in early phases but is more evident in advanced stages of the disease. Reduced levels of several metabolites were also associated with an unfavorable prognosis. The observed metabolomic alterations may contribute to inflammation, immune response inhibition and tumour growth, and may be explained by four nonexclusive views-differential synthesis, uptake, release, and degradation of metabolites. The interpretation that assimilates these views is the cross talk between neoplastic and normal cells in the tumour microenvironment or in more distant anatomical sites, connected by biofluids, signalling molecules and vesicles. Additional population samples to evaluate the details of these molecular processes may lead to the discovery of new biomarkers and novel strategies for OSCC prevention and treatment.

Neuronal Prosurvival Role of Ceramide Synthase 2 by Olidogendrocyte-to-Neuron Extracellular Vesicle Transfer

Ageing is associated with notorious alterations in neurons, i.e., in gene expression, mitochondrial function, membrane degradation or intercellular communication. However, neurons live for the entire lifespan of the individual. One of the reasons why neurons remain functional in elderly people is survival mechanisms prevail over death mechanisms. While many signals are either pro-survival or pro-death, others can play both roles. Extracellular vesicles (EVs) can signal both pro-toxicity and survival. We used young and old animals, primary neuronal and oligodendrocyte cultures and neuroblastoma and oligodendrocytic lines. We analysed our samples using a combination of proteomics and artificial neural networks, biochemistry and immunofluorescence approaches. We found an age-dependent increase in ceramide synthase 2 (CerS2) in cortical EVs, expressed by oligodendrocytes. In addition, we show that CerS2 is present in neurons via the uptake of oligodendrocyte-derived EVs. Finally, we show that age-associated inflammation and metabolic stress favour CerS2 expression and that oligodendrocyte-derived EVs loaded with CerS2 lead to the expression of the antiapoptotic factor Bcl2 in inflammatory conditions. Our study shows that intercellular communication is altered in the ageing brain, which favours neuronal survival through the transfer of oligodendrocyte-derived EVs containing CerS2.

Ceramide is implicated in humoral peripheral and intrathecal autoimmune response in MS patients

BACKGROUND

The disturbed metabolism of ceramide (Cer) is supposed to evoke the autoimmune response, contributing to MS pathology.

OBJECTIVES

To determine levels of anti-Cer immunoglobulins G (IgGs) in the CSF and serum of subjects with various phenotypes of MS, and to investigate relationships between levels of anti-Cer antibodies and MS-related variables.

METHODS

IgGs isolated from serum and the CSF of 68 MS patients and appropriate controls were examined for their reactivity to Cer subspecies. Their levels were compared between the studied groups and compartments, and analyzed with regard to clinical variables.

RESULTS

Increased levels of anti-C16:0-, C18:0-, C18:1-, C24:0- and C24:1-Cer IgGs were detected in the CSF and serum of MS patients in comparison with controls. For IgGs against particular Cer subspecies, correlations were found between their CSF and serum level, as well as with the Link index. Serum and the CSF anti-Cer IgGs differed between patients with clinically isolated syndrome (CIS) and relapsing-remitting MS from those with progressive MS. No correlations were found between anti-Cer IgGs and other MS-related clinical variables.

CONCLUSION

Patients with MS have shown altered panels of anti-Cer IgGs in the CSF and serum, which might suggest a relevant, though limited role of Cer as a target for autoimmune humoral response. Utility of antibodies against Cer subspecies as potential markers for MS activity and progression deserves further investigations.

Role of Ceramides and Lysosomes in Extracellular Vesicle Biogenesis, Cargo Sorting and Release

Cells have the ability to communicate with their immediate and distant neighbors through the release of extracellular vesicles (EVs). EVs facilitate intercellular signaling through the packaging of specific cargo in all type of cells, and perturbations of EV biogenesis, sorting, release and uptake is the basis of a number of disorders. In this review, we summarize recent advances of the complex roles of the sphingolipid ceramide and lysosomes in the journey of EV biogenesis to uptake.

Extracellular vesicles in β cell biology: Role of lipids in vesicle biogenesis, cargo, and intercellular signaling

BACKGROUND

Type 1 diabetes (T1D) is a complex autoimmune disorder whose pathogenesis involves an intricate interplay between β cells of the pancreatic islet, other islet cells, and cells of the immune system. Direct intercellular communication within the islet occurs via cell surface proteins and indirect intercellular communication has traditionally been seen as occurring via secreted proteins (e.g., endocrine hormones and cytokines). However, recent literature suggests that extracellular vesicles (EVs) secreted by β cells constitute an additional and biologically important mechanism for transmitting signals to within the islet.

SCOPE OF REVIEW

This review summarizes the general mechanisms of EV formation, with a particular focus on how lipids and lipid signaling pathways influence their formation and cargo. We review the implications of EV release from β cells for T1D pathogenesis, how EVs and their cargo might be leveraged as biomarkers of this process, and how EVs might be engineered as a therapeutic candidate to counter T1D outcomes.

MAJOR CONCLUSIONS

Islet β cells have been viewed as initiators and propagators of the cellular circuit giving rise to autoimmunity in T1D. In this context, emerging literature suggests that EVs may represent a conduit for communication that holds more comprehensive messaging about the β cells from which they arise. As the field of EV biology advances, it opens the possibility that intervening with EV formation and cargo loading could be a novel disease-modifying approach in T1D.

The Role of Exosomes as Mediators of Neuroinflammation in the Pathogenesis and Treatment of Alzheimer’s Disease

Alzheimer’s disease (AD) is a common neurodegenerative disease characterized by progressive dementia. Accumulation of β–amyloid peptide 1–42 and phosphorylation of tau protein in the brain are the two main pathological features of AD. However, comprehensive studies have shown that neuroinflammation also plays a crucial role in the pathogenesis of AD. Neuroinflammation is associated with neuronal death and abnormal protein aggregation and promotes the pathological process of β-amyloid peptide 1–42 and tau protein. The inflammatory components associated with AD include glial cells, complement system, cytokines and chemokines. In recent years, some researchers have focused on exosomes, a type of membrane nano vesicles. Exosomes can transport proteins, lipids, microRNAs and other signaling molecules to participate in a variety of signaling pathways for signal transmission or immune response, affecting the activity of target cells and participating in important pathophysiological processes. Therefore, exosomes play an essential role in intercellular communication and may mediate neuroinflammation to promote the development of AD. This paper reviews the occurrence and development of neuroinflammation and exosomes in AD, providing a deeper understanding of the pathogenesis of AD. Furthermore, the role of exosomes in the pathogenesis and treatment of AD is further described, demonstrating their potential as therapeutic targets for neuroinflammation and AD in the future.

Sphingolipid Players in Multiple Sclerosis: Their Influence on the Initiation and Course of the Disease

Sphingolipids (SLs) play a significant role in the nervous system, as major components of the myelin sheath, contributors to lipid raft formation that organize intracellular processes, as well as active mediators of transport, signaling and the survival of neurons and glial cells. Alterations in SL metabolism and content are observed in the course of central nervous system diseases, including multiple sclerosis (MS). In this review, we summarize the current evidence from studies on SLs (particularly gangliosides), which may shed new light upon processes underlying the MS background. The relevant aspects of these studies include alterations of the SL profile in MS, the role of antibodies against SLs and complexes of SL-ligand-invariant NKT cells in the autoimmune response as the core pathomechanism in MS. The contribution of lipid-raft-associated SLs and SL-laden extracellular vesicles to the disease etiology is also discussed. These findings may have diagnostic implications, with SLs and anti-SL antibodies as potential markers of MS activity and progression. Intriguing prospects of novel therapeutic options in MS are associated with SL potential for myelin repair and neuroprotective effects, which have not been yet addressed by the available treatment strategies. Overall, all these concepts are promising and encourage the further development of SL-based studies in the field of MS.

Ceramide Composition in Exosomes for Characterization of Glioblastoma Stem-Like Cell Phenotypes

Glioblastoma (GBM) is one of the most malignant central nervous system tumor types. Comparative analysis of GBM tissues has rendered four major molecular subtypes. From them, two molecular subtypes are mainly found in their glioblastoma cancer stem-like cells (GSCs) derived in vitro: proneural (PN) and mesenchymal (MES) with nodular (MES-N) and semi-nodular (MES-SN) disseminations, which exhibit different metabolic, growth, and malignancy properties. Many studies suggest that cancer cells communicate between them, and the surrounding microenvironment, via exosomes. Identifying molecular markers that allow the specific isolation of GSC-derived exosomes is key in the development of new therapies. However, the differential exosome composition produced by main GSCs remains unknown. The aim of this study was to determine ceramide (Cer) composition, one of the critical lipids in both cells and their cell-derived exosomes, from the main three GSC phenotypes using mass spectrometry-based lipidomics. GSCs from human tissue samples and their cell-derived exosomes were measured using ultra-high-performance liquid chromatography-quadrupole time-of-flight mass spectrometry (UHPLC/Q-TOF-MS) in an untargeted analysis. Complete characterization of the ceramide profile, in both cells and cell-derived exosomes from GSC phenotypes, showed differential distributions among them. Results indicate that such differences of ceramide are chain-length dependent. Significant changes for the C16 Cer and C24:1 Cer and their ratio were observed among GSC phenotypes, being different for cells and their cell-derived exosomes.

Activation of neutral sphingomyelinase 2 through hyperglycemia contributes to endothelial apoptosis via vesicle-bound intercellular transfer of ceramides

Background

Pro-apoptotic and pro-inflammatory ceramides are crucially involved in atherosclerotic plaque development. Local cellular ceramide accumulation mediates endothelial apoptosis, especially in type 2 diabetes mellitus, which is a major cardiovascular risk factor. In recent years, large extracellular vesicles (lEVs) have been identified as an important means of intercellular communication and as regulators of cardiovascular health and disease. A potential role for lEVs as vehicles for ceramide transfer and inductors of diabetes-associated endothelial apoptosis has never been investigated.

Methods and Results

A mass-spectrometric analysis of human coronary artery endothelial cells (HCAECs) and their lEVs revealed C16 ceramide (d18:1–16:0) to be the most abundant ceramide in lEVs and to be significantly increased in lEVs after hyperglycemic injury to HCAECs. The increased packaging of ceramide into lEVs after hyperglycemic injury was shown to be dependent on neutral sphingomyelinase 2 (nSMase2), which was upregulated in glucose-treated HCAECs. lEVs from hyperglycemic HCAECs induced apoptosis in the recipient HCAECs compared to native lEVs from untreated HCAECs. Similarly, lEVs from hyperglycemic mice after streptozotocin injection induced higher rates of apoptosis in murine endothelial cells compared to lEVs from normoglycemic mice. To generate lEVs with high levels of C16 ceramide, ceramide was applied exogenously and shown to be effectively packaged into the lEVs, which then induced apoptosis in lEV-recipient HCAECs via activation of caspase 3. Intercellular transfer of ceramide through lEVs was confirmed by use of a fluorescently labeled ceramide analogue. Treatment of HCAECs with a pharmacological inhibitor of nSMases (GW4869) or siRNA-mediated downregulation of nSMase2 abrogated the glucose-mediated effect on apoptosis in lEV-recipient cells. In contrast, for small EVs (sEVs), hyperglycemic injury or GW4869 treatment had no effect on apoptosis induction in sEV-recipient cells.

Conclusion

lEVs mediate the induction of apoptosis in endothelial cells in response to hyperglycemic injury through intercellular transfer of ceramides.

Graphical abstract

Supplementary Information

The online version contains supplementary material available at 10.1007/s00018-021-04049-5.

Dihydroceramide desaturase promotes the formation of intraluminal vesicles and inhibits autophagy to increase exosome production

Exosomes are important for cell-cell communication. Deficiencies in the human dihydroceramide desaturase gene, DEGS1, increase the dihydroceramide-to-ceramide ratio and cause hypomyelinating leukodystrophy. However, the disease mechanism remains unknown. Here, we developed an in vivo assay with spatially controlled expression of exosome markers in Drosophila eye imaginal discs and showed that the level and activity of the DEGS1 ortholog, Ifc, correlated with exosome production. Knocking out ifc decreased the density of the exosome precursor intraluminal vesicles (ILVs) in the multivesicular endosomes (MVEs) and reduced the number of exosomes released. While ifc overexpression and autophagy inhibition both enhanced exosome production, combining the two had no additive effect. Moreover, DEGS1 activity was sufficient to drive ILV formation in vitro. Together, DEGS1/Ifc controls the dihydroceramide-to-ceramide ratio and enhances exosome secretion by promoting ILV formation and preventing the autophagic degradation of MVEs. These findings provide a potential cause for the neuropathy associated with DEGS1-deficient mutations.

Inhibition of neutral sphingomyelinase 2 reduces extracellular vesicle release from neurons, oligodendrocytes, and activated microglial cells following acute brain injury

Extracellular Vesicles (EVs) are implicated in the spread of pathogenic proteinsin a growing number of neurological diseases. Given this, there is rising interest in developing inhibitors of Neutral Sphingomyelinase 2 (nSMase2), an enzyme critical in EV biogenesis. Our group recently discovered phenyl(R)-(1-(3-(3,4-dimethoxyphenyl)-2,6-dimethylimidazo[1,2-b]pyridazin-8-yl)pyrrolidin-3-yl)carbamate (PDDC), the first potent, selective, orally-available, and brain-penetrable nSMase2 inhibitor, capable of dose-dependently reducing EVs release in vitro and in vivo. Herein, using multiplexed Surface Plasmon Resonance imaging (SPRi), we evaluated which brain cell-derived EVs were affected by PDDC following acute brain injury. Mice were fed PDDC-containing chow at doses which gave steady PDDC brain exposures exceeding its nSMase2 IC₅₀. Mice were then administered an intra-striatal IL-1β injection and two hours later plasma and brain were collected. IL-1β injection significantly increased striatal nSMase2 activity which was completely normalized by PDDC. Using SPRi, we found that IL-1β-induced injury selectively increased plasma levels of CD171 + and PLP1 + EVs; this EV increase was normalized by PDDC. In contrast, GLAST1 + EVs were unchanged by IL-1β or PDDC. IL-1β injection selectively increased EVs released from activated versus non-activated microglia, indicated by the CD11b+/IB4 + ratio. The increase in EVs from CD11b + microglia was dramatically attenuated with PDDC. Taken together, our data demonstrate that following acute injury, brain nSMase2 activity is elevated. EVs released from neurons, oligodendrocytes, and activated microglial are increased in plasma and inhibition of nSMase2 with PDDC reduced these IL-1β-induced changes implicating nSMase2 inhibition as a therapeutic target for acute brain injury.

Intranasal Administration of Undifferentiated Oligodendrocyte Lineage Cells as a Potential Approach to Deliver Oligodendrocyte Precursor Cells into Brain

Oligodendrocyte precursor cell (OPC) migration is a mechanism involved in remyelination; these cells migrate from niches in the adult CNS. However, age and disease reduce the pool of OPCs; as a result, the remyelination capacity of the CNS decreases over time. Several experimental studies have introduced OPCs to the brain via direct injection or intrathecal administration. In this study, we used the nose-to brain pathway to deliver oligodendrocyte lineage cells (human oligodendroglioma (HOG) cells), which behave similarly to OPCs in vitro. To this end, we administered GFP-labelled HOG cells intranasally to experimental animals, which were subsequently euthanised at 30 or 60 days. Our results show that the intranasal route is a viable route to the CNS and that HOG cells administered intranasally migrate preferentially to niches of OPCs (clusters created during embryonic development and adult life). Our study provides evidence, albeit limited, that HOG cells either form clusters or adhere to clusters of OPCs in the brains of experimental animals.

The role of exosomes from BALF in lung disease

Exosomes are released from a variety of immune cells and nonimmune cells, the phospholipid vesicle bilayer membrane structure actively secreted into tissues. Recently, exosomes were demonstrated to be effectively delivered proteins, cholesterol, lipids, and amounts of DNA, mRNA, and noncoding RNAs to a target cell or tissue from a host cell. These can be detected in blood, urine, exhaled breath condensates, bronchoalveolar lavage fluid (BALF), ascites, and cerebrospinal fluid. BALF is a clinical examination method for obtaining alveolar cells and biochemical components, reflecting changes in the lungs, so it is also called liquid biopsy. Exosomes from BALF become a new method for intercellular communication and well‐documented in various pulmonary diseases. In chronic obstructive pulmonary disease (COPD), BALF exosomes can predict the degree of COPD damage and serve as an effective monitoring indicator for airflow limitation and airway remodeling. It also mediates antigen presentation in the airways to the adaptive immune system as well as costimulatory effects. Furthermore, BALF exosomes from acute lung injury and infective diseases are closely related to various infections and lack of oxygen status. BALF exosomes play an important role in the diagnosis and prognosis of lung cancer. The effect of immunomodulatory role for BALF exosomes in adaptive and innate immune responses has been studied in sarcoidosis. The intercellular communication in the microenvironment of BALF exosomes in pulmonary fibrosis and lung remodeling have been studied. In this review, we summarize the novel findings of exosomes in BALF, executed function by protein, miRNA, DNA cytokine, and so on in several pulmonary diseases.

Cocaine Induces Sex-Associated Changes in Lipid Profiles of Brain Extracellular Vesicles

Cocaine is a highly addictive stimulant with diverse effects on physiology. Recent studies indicate the involvement of extracellular vesicles (EVs) secreted by neural cells in the cocaine addiction process. It is hypothesized that cocaine affects secretion levels of EVs and their cargos, resulting in modulation of synaptic transmission and plasticity related to addiction physiology and pathology. Lipids present in EVs are important for EV formation and for intercellular lipid exchange that may trigger physiological and pathological responses, including neuroplasticity, neurotoxicity, and neuroinflammation. Specific lipids are highly enriched in EVs compared to parent cells, and recent studies suggest the involvement of various lipids in drug-induced synaptic plasticity during the development and maintenance of addiction processes. Therefore, we examined interstitial small EVs isolated from the brain of mice treated with either saline or cocaine, focusing on the effects of cocaine on the lipid composition of EVs. We demonstrate that 12 days of noncontingent repeated cocaine (10 mg/kg) injections to mice, which induce locomotor sensitization, cause lipid composition changes in brain EVs of male mice as compared with saline-injected controls. The most prominent change is the elevation of GD1a ganglioside in brain EVs of males. However, cocaine does not affect the EV lipid profiles of the brain in female mice. Understanding the relationship between lipid composition in EVs and vulnerability to cocaine addiction may provide insight into novel targets for therapies for addiction.

New Insights into Multiple Sclerosis Mechanisms: Lipids on the Track to Control Inflammation and Neurodegeneration

Multiple sclerosis (MS) is a central nervous system disease with complex pathogenesis, including two main processes: immune-mediated inflammatory demyelination and progressive degeneration with axonal loss. Despite recent progress in our understanding and management of MS, availability of sensitive and specific biomarkers for these both processes, as well as neuroprotective therapeutic options targeted at progressive phase of disease, are still being sought. Given their abundance in the myelin sheath, lipids are believed to play a central role in underlying immunopathogenesis in MS and seem to be a promising subject of investigation in this field. On the basis of our previous research and a review of the literature, we discuss the current understanding of lipid-related mechanisms involved in active relapse, remission, and progression of MS. These insights highlight potential usefulness of lipid markers in prediction or monitoring the course of MS, particularly in its progressive stage, still insufficiently addressed. Furthermore, they raise hope for new, effective, and stage-specific treatment options, involving lipids as targets or carriers of therapeutic agents.

The Mystery of Red Blood Cells Extracellular Vesicles in Sleep Apnea with Metabolic Dysfunction

Sleep is very important for overall health and quality of life, while sleep disorder has been associated with several human diseases, namely cardiovascular, metabolic, cognitive, and cancer-related alterations. Obstructive sleep apnea (OSA) is the most common respiratory sleep-disordered breathing, which is caused by the recurrent collapse of the upper airway during sleep. OSA has emerged as a major public health problem and increasing evidence suggests that untreated OSA can lead to the development of various diseases including neurodegenerative diseases. In addition, OSA may lead to decreased blood oxygenation and fragmentation of the sleep cycle. The formation of free radicals or reactive oxygen species (ROS) can emerge and react with nitric oxide (NO) to produce peroxynitrite, thereby diminishing the bioavailability of NO. Hypoxia, the hallmark of OSA, refers to a decline of tissue oxygen saturation and affects several types of cells, playing cell-to-cell communication a vital role in the outcome of this interplay. Red blood cells (RBCs) are considered transporters of oxygen and nutrients to the tissues, and these RBCs are important interorgan communication systems with additional functions, including participation in the control of systemic NO metabolism, redox regulation, blood rheology, and viscosity. RBCs have been shown to induce endothelial dysfunction and increase cardiac injury. The mechanistic links between changes of RBC functional properties and cardiovascular are largely unknown. Extracellular vesicles (EVs) are secreted by most cell types and released in biological fluids both under physiological and pathological conditions. EVs are involved in intercellular communication by transferring complex cargoes including proteins, lipids, and nucleic acids from donor cells to recipient cells. Advancing our knowledge about mechanisms of RBC-EVs formation and their pathophysiological relevance may help to shed light on circulating EVs and to translate their application to clinical practice. We will focus on the potential use of RBC-EVs as valuable diagnostic and prognostic biomarkers and state-specific cargoes, and possibilities as therapeutic vehicles for drug and gene delivery. The use of RBC-EVs as a precision medicine for the diagnosis and treatment of the patient with sleep disorder will improve the prognosis and the quality of life in patients with cardiovascular disease (CVD).

Asthmatic condition induced the activity of exosome secretory pathway in rat pulmonary tissues

BACKGROUND

The recent studies highlighted the critical role of exosomes in the regulation of inflammation. Here, we investigated the dynamic biogenesis of the exosomes in the rat model of asthma.

RESULTS

Our finding showed an increase in the expression of IL-4 and the suppression of IL-10 in asthmatic lung tissues compared to the control samples (p < 0.05). Along with the promotion of IL-4, the protein level of TNF-α was induced, showing an active inflammatory status in OVA-sensitized rats. According to our data, the promotion of asthmatic responses increased exosome biogenesis indicated by increased CD63 levels and acetylcholine esterase activity compared to the normal condition (p < 0.05).

CONCLUSION

Data suggest that the stimulation of inflammatory response in asthmatic rats could simultaneously increase the paracrine activity of pulmonary cells via the exosome biogenesis. Exosome biogenesis may correlate with the inflammatory response.

Lysosomal TRPML1 Channel: Implications in Cardiovascular and Kidney Diseases

Lysosomal ion channels mediate ion flux from lysosomes and regulate membrane potential across the lysosomal membrane, which are essential for lysosome biogenesis, nutrient sensing, lysosome trafficking, lysosome enzyme activity, and cell membrane repair. As a cation channel, the transient receptor potential mucolipin 1 (TRPML1) channel is mainly expressed on lysosomes and late endosomes. Recently, the normal function of TRPML1 channels has been demonstrated to be important for the maintenance of cardiovascular and renal glomerular homeostasis and thereby involved in the pathogenesis of some cardiovascular and kidney diseases. In arterial myocytes, it has been found that Nicotinic Acid Adenine Dinucleotide Phosphate (NAADP), an intracellular second messenger, can induce Ca²⁺ release through the lysosomal TRPML1 channel, leading to a global Ca²⁺ release response from the sarcoplasmic reticulum (SR). In podocytes, it has been demonstrated that lysosomal TRPML1 channels control lysosome trafficking and exosome release, which contribute to the maintenance of podocyte functional integrity. The defect or functional deficiency of lysosomal TRPML1 channels has been shown to critically contribute to the initiation and development of some chronic degeneration or diseases in the cardiovascular system or kidneys. Here we briefly summarize the current evidence demonstrating the regulation of lysosomal TRPML1 channel activity and related signaling mechanisms. We also provide some insights into the canonical and noncanonical roles of TRPML1 channel dysfunction as a potential pathogenic mechanism for certain cardiovascular and kidney diseases and associated therapeutic strategies.

Autophagy-dependent ferroptosis drives tumor-associated macrophage polarization via release and uptake of oncogenic KRAS protein

KRAS is the most frequently mutated oncogene in human neoplasia. Despite a large investment to understand the effects of KRAS mutation in cancer cells, the direct effects of the oncogenetic KRAS activation on immune cells remain elusive. Here, we report that extracellular KRASG12D is essential for pancreatic tumor-associated macrophage polarization. Oxidative stress induces KRASG12D protein release from cancer cells succumbing to autophagy-dependent ferroptosis. Extracellular KRASG12D packaged into exosomes then is taken up by macrophages through an AGER-dependent mechanism. KRASG12D causes macrophages to switch to an M2-like pro-tumor phenotype via STAT3-dependent fatty acid oxidation. Consequently, the disruption of KRASG12D release and uptake can abolish the macrophage-mediated stimulation of pancreatic adenocarcinomas in mouse models. Importantly, the level of KRASG12D expression in macrophages correlates with poor survival in pancreatic cancer patients. These findings not only identify extracellular KRASG12D as a key mediator of cancer cell-macrophage communication, but also provide a novel KRAS-targeted anticancer strategy. Abbreviations: DAMP, damage-associated molecular pattern; PBMCMs, peripheral blood mononuclear cell-derived macrophages; PDAC, pancreatic ductal adenocarcinoma; s.c., subcutaneously; TAMs, tumor-associated macrophages; TME, tumor microenvironment.

The role of exosome lipids in central nervous system diseases

Central nervous system (CNS) diseases are common diseases that threaten human health. The CNS is highly enriched in lipids, which play important roles in maintaining normal physiological functions of the nervous system. Moreover, many CNS diseases are closely associated with abnormal lipid metabolism. Exosomes are a subtype of extracellular vesicles (EVs) secreted from multivesicular bodies (MVBs) . Through novel forms of intercellular communication, exosomes secreted by brain cells can mediate inter-neuronal signaling and play important roles in the pathogenesis of CNS diseases. Lipids are essential components of exosomes, with cholesterol and sphingolipid as representative constituents of its bilayer membrane. In the CNS, lipids are closely related to the formation and function of exosomes. Their dysregulation causes abnormalities in exosomes, which may, in turn, lead to dysfunctions in inter-neuronal communication and promote diseases. Therefore, the role of lipids in the treatment of neurological diseases through exosomes has received increasing attention. The aim of this review is to discuss the relationship between lipids and exosomes and their roles in CNS diseases.

Distinctive sphingolipid patterns in chronic multiple sclerosis lesions

Multiple sclerosis (MS) is a CNS disease characterized by immune-mediated demyelination and progressive axonal loss. MS-related CNS damage and its clinical course have two main phases: active and inactive/progressive. Reliable biomarkers are being sought to allow identification of MS pathomechanisms and prediction of its course. The purpose of this study was to identify sphingolipid (SL) species as candidate biomarkers of inflammatory and neurodegenerative processes underlying MS pathology. We performed sphingolipidomic analysis by HPLC-tandem mass spectrometry to determine the lipid profiles in post mortem specimens from the normal-appearing white matter (NAWM) of the normal CNS (nCNS) from subjects with chronic MS (active and inactive lesions) as well as from patients with other neurological diseases. Distinctive SL modification patterns occurred in specimens from MS patients with chronic inactive plaques with respect to NAWM from the nCNS and active MS (Ac-MS) lesions. Chronic inactive MS (In-MS) lesions were characterized by decreased levels of dihydroceramide (dhCer), ceramide (Cer), and SM subspecies, whereas levels of hexosylceramide and Cer 1-phosphate (C1P) subspecies were significantly increased in comparison to NAWM of the nCNS as well as Ac-MS plaques. In contrast, Ac-MS lesions were characterized by a significant increase of major dhCer subspecies in comparison to NAWM of the nCNS. These results suggest the existence of different SL metabolic pathways in the active versus inactive phase within progressive stages of MS. Moreover, they suggest that C1P could be a new biomarker of the In-MS progressive phase, and its detection may help to develop future prognostic and therapeutic strategies for the disease.

ISL2 modulates angiogenesis through transcriptional regulation of ANGPT2 to promote cell proliferation and malignant transformation in oligodendroglioma

Oligodendroglioma is an important type of lower-grade glioma (LGG), which is a slowly progressing brain tumor. Many LGGs eventually transform into a more aggressive or malignant type. Enhanced angiogenesis is a characteristic of malignantly transformed oligodendroglioma (m-oligodendroglioma). However, the pathogenesis and signaling pathways associated with angiogenesis and proliferation in m-oligodendroglioma are not well understood. In this study, we identified that Insulin Gene Enhancer Protein (ISL2) and its angiogenic capacity were inversely related to survival according to LGG patient data from an online database, and this was further confirmed with pathological LGG patient samples, including malignantly transformed samples, by detecting the expression of ISL2, the angiogenic markers vascular endothelial growth factor (VEGFA) and CD31 and the proliferation marker Ki-67. We then established novel oligodendroglioma patient tumor-derived orthotopic xenograft mouse models and cell lines to verify the role of ISL2 in regulating angiogenesis to promote oligodendroglioma growth and malignant transformation. Furthermore, ISL2 regulated ANGPT2 transcription by binding to the ANGPT2 promoter. Then, ANGPT2, a downstream gene, activated angiogenesis through VEGFA to promote oligodendroglioma malignant transformation. Finally, combining AAV-ISL2-shRNA with temozolomide suppressed oligodendroglioma progression more effectively than either monotherapy in vivo and in vitro. Thus, hypoxia-induced ISL2 regulated ANGPT2, which subsequently induced angiogenesis to promote oligodendroglioma growth and malignant transformation. Malignancy was accompanied by worsened hypoxia inside the tumor mass, creating a positive feedback loop. In conclusion, this study suggests that ISL2 is a biomarker for oligodendroglioma progression and that anti-ISL2 therapy may offer a potential clinical strategy for treating m-oligodendroglioma.

The Emerging Role of Extracellular Vesicles in the Glioma Microenvironment: Biogenesis and Clinical Relevance

Gliomas are a diverse group of brain tumors comprised of malignant cells ('tumor' cells) and non-malignant 'normal' cells, including neural (neurons, glia), inflammatory (microglia, macrophage) and vascular cells. Tumor heterogeneity arises in part because, within the glioma mass, both 'tumor' and 'normal' cells secrete factors that form a unique microenvironment to influence tumor progression. Extracellular vesicles (EVs) are critical mediators of intercellular communication between immediate cellular neighbors and distantly located cells in healthy tissues/organs and in tumors, including gliomas. EVs mediate cell-cell signaling as carriers of nucleic acid, lipid and protein cargo, and their content is unique to cell types and physiological states. EVs secreted by non-malignant neural cells have important physiological roles in the healthy brain, which can be altered or co-opted to promote tumor progression and metastasis, acting in combination with glioma-secreted EVs. The cell-type specificity of EV content means that 'vesiculome' data can potentially be used to trace the cell of origin. EVs may also serve as biomarkers to be exploited for disease diagnosis and to assess therapeutic progress. In this review, we discuss how EVs mediate intercellular communication in glioma, and their potential role as biomarkers and readouts of a therapeutic response.

Hsv-1 Endocytic Entry into a Human Oligodendrocytic Cell Line is Mediated by Clathrin and Dynamin but Not Caveolin

Endocytosis is a pathway used by viruses to enter cells that can be classified based on the proteins involved, such as dynamin, clathrin or caveolin. Although the entry of herpes simplex type 1 (HSV-1) by endocytosis has been documented in different cell types, its dependence on clathrin has not been described whereas its dependence on dynamin has been shown according to the cell line used. The present work shows how clathrin-mediated endocytosis (CME) is one way that HSV-1 infects the human oligodendroglial (HOG) cell line. Partial dynamin inhibition using dynasore revealed a relationship between decrease of infection and dynamin inhibition, measured by viral titration and immunoblot. Co-localization between dynamin and HSV-1 was verified by immunofluorescence at the moment of viral entry into the cell. Inhibition by chlorpromazine revealed that viral progeny also decreased when clathrin was partially inhibited in our cell line. RT-qPCR of immediately early viral genes, specific entry assays and electron microscopy all confirmed clathrin's participation in HSV-1 entry into HOG cells. In contrast, caveolin entry assays showed no effect on the entry of this virus. Therefore, our results suggest the participation of dynamin and clathrin during endocytosis of HSV-1 in HOG cells.

Podocyte Lysosome Dysfunction in Chronic Glomerular Diseases

Podocytes are visceral epithelial cells covering the outer surface of glomerular capillaries in the kidney. Blood is filtered through the slit diaphragm of podocytes to form urine. The functional and structural integrity of podocytes is essential for the normal function of the kidney. As a membrane-bound organelle, lysosomes are responsible for the degradation of molecules via hydrolytic enzymes. In addition to its degradative properties, recent studies have revealed that lysosomes may serve as a platform mediating cellular signaling in different types of cells. In the last decade, increasing evidence has revealed that the normal function of the lysosome is important for the maintenance of podocyte homeostasis. Podocytes have no ability to proliferate under most pathological conditions; therefore, lysosome-dependent autophagic flux is critical for podocyte survival. In addition, new insights into the pathogenic role of lysosome and associated signaling in podocyte injury and chronic kidney disease have recently emerged. Targeting lysosomal functions or signaling pathways are considered potential therapeutic strategies for some chronic glomerular diseases. This review briefly summarizes current evidence demonstrating the regulation of lysosomal function and signaling mechanisms as well as the canonical and noncanonical roles of podocyte lysosome dysfunction in the development of chronic glomerular diseases and associated therapeutic strategies.

Lipidomic Analysis of Cells and Extracellular Vesicles from High- and Low-Metastatic Triple-Negative Breast Cancer

Extracellular vesicles (EVs) are lipid bilayer nanovesicles secreted from almost all cells including cancer. Cancer-derived EVs contribute to cancer progression and malignancy via educating the surrounding normal cells. In breast cancer, epidemiological and experimental observations indicated that lipids are associated with cancer malignancy. However, lipid compositions of breast cancer EVs and their contributions to cancer progression are unexplored. In this study, we performed a widely targeted quantitative lipidomic analysis in cells and EVs derived from high- and low-metastatic triple-negative breast cancer cell lines, using supercritical fluid chromatography fast-scanning triple-quadrupole mass spectrometry. We demonstrated the differential lipid compositions between EVs and cells of their origin, and between high- and low-metastatic cell lines. Further, we demonstrated EVs from highly metastatic breast cancer accumulated unsaturated diacylglycerols (DGs) compared with EVs from lower-metastatic cells, without increasing the amount in cells. The EVs enriched with DGs could activate the protein kinase D signaling pathway in endothelial cells, which can lead to stimulated angiogenesis. Our results indicate that lipids are selectively loaded into breast cancer EVs to support tumor progression.

SNHG9, delivered by adipocyte-derived exosomes, alleviates inflammation and apoptosis of endothelial cells through suppressing TRADD expression

Exosomes are membrane-derived vesicles and play a critical role in cell signaling by transferring RNAs and proteins to target cells through fusion with the cell membrane. Long non-coding RNA-small nucleolar RNA host gene 9 (lncRNA-SNHG9) was proven to be an important element in lncRNA-mRNA interaction networks during adipocyte differentiation, suggesting its potential involvement in the development of obesity, an important risk factor of cardiovascular and cerebrovascular endothelial dysfunction. However, the role of lncRNA-SNHG9 within the exosome in endothelial dysfunction of obese patients is largely unknown. In this study, we proved that adipocytes-derived exosomal SNHG9 were downregulated in obese persons and further decreased in obese individuals with endothelial dysfunction. Functional experimentations demonstrated that adipocytes-derived exosomal SNHG9 alleviated inflammation and apoptosis in endothelial cells. Bioinformatic analysis revealed that there was a potential interaction between SNHG9 and the TNF receptor type 1-associated death domain protein (TRADD) mRNA. Then, RNA-binding protein immunoprecipitation assay based on Ago2 antibody and ribonuclease protection assay demonstrated that exosomal SNHG9 directly bound to a specific region in TRADD mRNA sequence and formed an RNA dimeric inducible silencing complex. Moreover, knockdown of TRADD markedly inhibited inflammation and apoptosis in human umbilical vein endothelial cells (HUVECs), whereas overexpression of TRADD dramatically neutralized the protective effect of exosomal SNHG9 on epithelial dysfunction. Therefore, SNHG9 could prevent endothelial dysfunction in obese patients by suppressing inflammation and apoptosis, indicating that SNHG9 may be a potential therapeutic target for obese patients with endothelial dysfunction.

Microbiome and motor neuron diseases

The microbiome is the ecological community of commensal, symbiotic, and pathogenic microorganisms that share our body space (Medical and Health Genomics, 2016, page 15-28). The human gut is the location where the maximum number of microorganisms can be found. Among the different microorganisms they can be broadly classified into two groups: the beneficial and harmful. In the human gut there is always a balance between the beneficial and the opportunistic microorganism which maintains human health. However, if the balance is not maintained and homeostasis is disturbed, with an increase in opportunistic microorganisms, it may result in various diseases like inflammatory bowel disease, irritable bowel disease, ulcerative colitis, Crohn's disease, colorectal cancer, metabolic disorders and neurodegenerative diseases including motor neuron diseases. In the present chapter we discuss the role of gut bacteria in motor neuron diseases like multiple sclerosis, Parkinson's disease and amyotrophic lateral sclerosis.

Multiple Sclerosis: Melatonin, Orexin, and Ceramide Interact with Platelet Activation Coagulation Factors and Gut-Microbiome-Derived Butyrate in the Circadian Dysregulation of Mitochondria in Glia and Immune Cells

Recent data highlight the important roles of the gut microbiome, gut permeability, and alterations in mitochondria functioning in the pathophysiology of multiple sclerosis (MS). This article reviews such data, indicating two important aspects of alterations in the gut in the modulation of mitochondria: (1) Gut permeability increases toll-like receptor (TLR) activators, viz circulating lipopolysaccharide (LPS), and exosomal high-mobility group box (HMGB)1. LPS and HMGB1 increase inducible nitric oxide synthase and superoxide, leading to peroxynitrite-driven acidic sphingomyelinase and ceramide. Ceramide is a major driver of MS pathophysiology via its impacts on glia mitochondria functioning; (2) Gut dysbiosis lowers production of the short-chain fatty acid, butyrate. Butyrate is a significant positive regulator of mitochondrial function, as well as suppressing the levels and effects of ceramide. Ceramide acts to suppress the circadian optimizers of mitochondria functioning, viz daytime orexin and night-time melatonin. Orexin, melatonin, and butyrate increase mitochondria oxidative phosphorylation partly via the disinhibition of the pyruvate dehydrogenase complex, leading to an increase in acetyl-coenzyme A (CoA). Acetyl-CoA is a necessary co-substrate for activation of the mitochondria melatonergic pathway, allowing melatonin to optimize mitochondrial function. Data would indicate that gut-driven alterations in ceramide and mitochondrial function, particularly in glia and immune cells, underpin MS pathophysiology. Aryl hydrocarbon receptor (AhR) activators, such as stress-induced kynurenine and air pollutants, may interact with the mitochondrial melatonergic pathway via AhR-induced cytochrome P450 (CYP)1b1, which backward converts melatonin to N-acetylserotonin (NAS). The loss of mitochnodria melatonin coupled with increased NAS has implications for altered mitochondrial function in many cell types that are relevant to MS pathophysiology. NAS is increased in secondary progressive MS, indicating a role for changes in the mitochondria melatonergic pathway in the progression of MS symptomatology. This provides a framework for the integration of diverse bodies of data on MS pathophysiology, with a number of readily applicable treatment interventions, including the utilization of sodium butyrate.

Glia-derived exosomes: Promising therapeutic targets

Glia is an important component of the nervous system that is involved in neurotransmitter uptake, signal transduction, myelin synthesis, neurodevelopment, and immune response. Exosomes are extracellular vesicles that are secreted from certain types of cells, and are known to mediate glia function. Glia-derived exosomes (GDEs) can transport proteins, nucleotides and cellular waste, and exert both protective and toxic effects on the nervous system. GDEs promote glia-neuron communication, anti-stress responses, anti-inflammation and neurite outgrowth, and may also be involved in neurological disease such as glioma, glioblastoma, Alzheimer's disease, Parkinson disease and neuronal HIV infections. This review summarizes the current research on GDEs and their functions, with emphasis on their therapeutic potential.

Inflammatory role of extracellular sphingolipids in Cystic Fibrosis

Ceramide is emerging as one of the players of inflammation in lung diseases. However, data on its inflammatory role in Cystic Fibrosis (CF) as part of the extracellular machinery driven by lung mesenchymal stem cells (MSCs)-derived extracellular vesicles (EVs) are missing. We obtained an in vitro model of CF-MSC by treating control human lung MSCs with a specific CFTR inhibitor. We characterized EVs populations derived from MSCs (ctr EVs) and CF-MSCs (CF-EVs) and analyzed their sphingolipid profile by LC-MS/MS. To evaluate their immunomodulatory function, we treated an in vitro human model of CF, with both EVs populations. Our data show that the two EVs populations differ for the average size, amount, and rate of uptake. CF-EVs display higher ceramide and dihydroceramide accumulation as compared to control EVs, suggesting the involvement of the de novo biosynthesis pathway in the parental CF-MSCs. Higher sphingomyelinase activity in CF-MSCs, driven by inflammation-induced ceramide accumulation, sustains the exocytosis of vesicles that export new formed pro-inflammatory ceramide. Our results suggest that CFTR dysfunction associates with an enhanced sphingolipid metabolism leading to the release of EVs that export the excess of pro-inflammatory Cer to the recipient cells, thus contributing to maintain the unresolved inflammatory status of CF.

Reappraisal of Human HOG and MO3.13 Cell Lines as a Model to Study Oligodendrocyte Functioning

Myelination of neuronal axons is essential for proper brain functioning and requires mature myelinating oligodendrocytes (myOLs). The human OL cell lines HOG and MO3.13 have been widely used as in vitro models to study OL (dys) functioning. Here we applied a number of protocols aimed at differentiating HOG and MO3.13 cells into myOLs. However, none of the differentiation protocols led to increased expression of terminal OL differentiation or myelin-sheath formation markers. Surprisingly, the applied protocols did cause changes in the expression of markers for early OLs, neurons, astrocytes and Schwann cells. Furthermore, we noticed that mRNA expression levels in HOG and MO3.13 cells may be affected by the density of the cultured cells. Finally, HOG and MO3.13 co-cultured with human neuronal SH-SY5Y cells did not show myelin formation under several pro-OL-differentiation and pro-myelinating conditions. Together, our results illustrate the difficulty of inducing maturation of HOG and MO3.13 cells into myOLs, implying that these oligodendrocytic cell lines may not represent an appropriate model to study the (dys)functioning of human (my)OLs and OL-linked disease mechanisms.

A challenging case of concurrent multiple sclerosis and anaplastic astrocytoma

Background:

Cases of gliomas coexisting with multiple sclerosis (MS) have been described over the past few decades. However, due to the complex clinical and radiological traits inherent to both entities, this concurrent phenomenon remains difficult to diagnose. Much has been debated about whether this coexistence is incidental or mirrors a poorly understood neoplastic phenomenon engaging glial cells in the regions of demyelination.

Case Description:

We present the case of a 41-year-old patient diagnosed with a left-sided frontal contrast enhancing lesion initially assessed as a tumefactive MS. Despite systemic treatment, the patient gradually developed signs of mass effect, which led to decompressive surgery. The initial microscopic evaluation demonstrated the presence of MS and oligodendroglioma; the postoperative evolution proved complex due to a series of MS-relapses and tumor recurrence. An ulterior revaluation of the samples for the purpose of this report showed an MS-concurrent anaplastic astrocytoma. We describe all relevant clinical aspects of this case and review the medical literature for possible causal mechanisms.

Conclusion:

Although cases of concurrent glioma and MS remain rare, we present a case illustrating this phenomenon and explore a number of theories behind a potential causal relationship.

Crucial Role of Extracellular Vesicles in Bronchial Asthma

Extracellular vesicles (EVs) are circulating vesicles secreted by various cell types. EVs are classified into three groups according to size, structural components, and generation process of vesicles: exosomes, microvesicles, and apoptotic bodies. Recently, EVs have been considered to be crucial for cell-to-cell communications and homeostasis because they contain intracellular proteins and nucleic acids. Epithelial cells from mice suffering from bronchial asthma (BA) secrete more EVs and suppress inflammation-induced EV production. Moreover, microarray analyses of bronchoalveolar lavage fluid have revealed that several microRNAs are useful novel biomarkers of BA. Mesenchymal stromal cell-derived EVs are possible candidates of novel BA therapy. In this review, we highlight the biologic roles of EVs in BA and review novel EV-targeted therapy to help understanding by clinicians and biologists.

Adipose Tissue Exosomal Proteomic Profile Reveals a Role on Placenta Glucose Metabolism in Gestational Diabetes Mellitus

CONTEXT

Molecules produced by adipose tissue (AT) function as an endocrine link between maternal AT and fetal growth by regulating placental function in normal women and women with gestational diabetes mellitus (GDM).

OBJECTIVE

We hypothesized that AT-derived exosomes (exo-AT) from women with GDM would carry a specific set of proteins that influences glucose metabolism in the placenta.

DESIGN

Exosomes were isolated from omental AT-conditioned media from normal glucose tolerant (NGT) pregnant women (n = 65) and pregnant women with GDM (n = 82). Sequential window acquisition of all theoretical fragment ion spectra mass spectrometry was used to construct a small ion library from AT and exosomal proteins, followed by ingenuity pathway analysis to determine the canonical pathways and biofunctions. The effect of exosomes on human placental cells was determined using a Human Glucose Metabolism RT2 Profiler PCR array.

RESULTS

The number of exosomes (vesicles/μg of tissue/24 hours) was substantially (1.7-fold) greater in GDM than in NGT, and the number of exosomes correlated positively with the birthweight Z score. Ingenuity pathway analysis of the exosomal proteins revealed differential expression of the proteins targeting the sirtuin signaling pathway, oxidative phosphorylation, and mechanistic target of rapamycin signaling pathway in GDM compared with NGT. GDM exo-AT increased the expression of genes associated with glycolysis and gluconeogenesis in placental cells compared with the effect of NGT exo-AT.

CONCLUSIONS

Our findings are consistent with the possibility that AT exosomes play an important role in mediating the changes in placental function in GDM and might be responsible for some of the adverse consequences in this pregnancy complication, such as fetal overgrowth.

Roles of Extracellular Vesicles in High-Grade Gliomas: Tiny Particles with Outsized Influence

High-grade gliomas, particularly glioblastomas (grade IV), are devastating diseases with dismal prognoses; afflicted patients seldom live longer than 15 months, and their quality of life suffers immensely. Our current standard-of-care therapy has remained essentially unchanged for almost 15 years, with little new therapeutic progress. We desperately need a better biologic understanding of these complicated tumors in a complicated organ. One area of rejuvenated study relates to extracellular vesicles (EVs)-membrane-enclosed nano- or microsized particles that originate from the endosomal system or are shed from the plasma membrane. EVs contribute to tumor heterogeneity (including the maintenance of glioma stem cells or their differentiation), the impacts of hypoxia (angiogenesis and coagulopathies), interactions amid the tumor microenvironment (concerning the survival of astrocytes, neurons, endothelial cells, blood vessels, the blood-brain barrier, and the ensuing inflammation), and influences on the immune system (both stimulatory and suppressive). This article reviews glioma EVs and the ways that EVs manifest themselves as autocrine, paracrine, and endocrine factors in proximal and distal intra- and intercellular communications. The reader should note that there is much controversy, and indeed confusion, in the field over the exact roles for EVs in many biological processes, and we will engage some of these difficulties herein.

Exosomes in Allergic Airway Diseases

PURPOSE OF REVIEW

This review will cover what is known regarding exosomes and allergy, and furthermore discuss novel mechanism of exosome-mediated immune modulation and metabolic regulation via the transfer of mitochondria.

RECENT FINDINGS

Exosomes are nano-sized extracellular vesicles (EVs) derived from the endosome that play a direct role in governing physiological and pathological conditions by transferring bioactive cargo such as proteins, enzymes, nucleic acids (miRNA, mRNA, DNA), and metabolites. Recent evidence suggest that exosomes may signal in autocrine but, most importantly, in paracrine and endocrine manner, being taken up by neighboring cells or carried to distant sites. Exosomes also mediate immunogenic responses, such as antigen presentation and inflammation. In asthma and allergy, exosomes facilitate cross-talk between immune and epithelial cells, and drive site-specific inflammation through the generation of pro-inflammatory mediators like leukotrienes. Recent studies suggest that myeloid cell-generated exosomes transfer mitochondria to lymphocytes. Exosomes are nano-sized mediators of the immune system which can modulate responses through antigen presentation, and the transfer of pro- and anti-inflammatory mediators. In addition to conventional mechanisms of immune modulation, exosomes may act as a novel courier of functional mitochondria that is capable of modulating the recipient cells bioenergetics, resulting in altered cellular responses. The transfer of mitochondria and modulation of bioenergetics may result in immune activation or dampening depending on the context.

Very Long-Chain C24:1 Ceramide Is Increased in Serum Extracellular Vesicles with Aging and Can Induce Senescence in Bone-Derived Mesenchymal Stem Cells

Extracellular vesicles (EVs), including exosomes and microvesicles, function in cell-to-cell communication through delivery of proteins, lipids and microRNAs to target cells via endocytosis and membrane fusion. These vesicles are enriched in ceramide, a sphingolipid associated with the promotion of cell senescence and apoptosis. We investigated the ceramide profile of serum exosomes from young (24⁻40 yrs.) and older (75⁻90 yrs.) women and young (6⁻10 yrs.) and older (25⁻30 yrs.) rhesus macaques to define the role of circulating ceramides in the aging process. EVs were isolated using size-exclusion chromatography. Proteomic analysis was used to validate known exosome markers from Exocarta and nanoparticle tracking analysis used to characterize particle size and concentration. Specific ceramide species were identified with lipidomic analysis. Results show a significant increase in the average amount of C24:1 ceramide in EVs from older women (15.4 pmol/sample) compared to those from younger women (3.8 pmol/sample). Results were similar in non-human primate serum samples with increased amounts of C24:1 ceramide (9.3 pmol/sample) in older monkeys compared to the younger monkeys (1.8 pmol/sample). In vitro studies showed that primary bone-derived mesenchymal stem cells (BMSCs) readily endocytose serum EVs, and serum EVs loaded with C24:1 ceramide can induce BMSC senescence. Elevated ceramide levels have been associated with poor cardiovascular health and memory impairment in older adults. Our data suggest that circulating EVs carrying C24:1 ceramide may contribute directly to cell non-autonomous aging.

Machine-learning based lipid mediator serum concentration patterns allow identification of multiple sclerosis patients with high accuracy

Based on increasing evidence suggesting that MS pathology involves alterations in bioactive lipid metabolism, the present analysis was aimed at generating a complex serum lipid-biomarker. Using unsupervised machine-learning, implemented as emergent self-organizing maps of neuronal networks, swarm intelligence and Minimum Curvilinear Embedding, a cluster structure was found in the input data space comprising serum concentrations of d = 43 different lipid-markers of various classes. The structure coincided largely with the clinical diagnosis, indicating that the data provide a basis for the creation of a biomarker (classifier). This was subsequently assessed using supervised machine-learning, implemented as random forests and computed ABC analysis-based feature selection. Bayesian statistics-based biomarker creation was used to map the diagnostic classes of either MS patients (n = 102) or healthy subjects (n = 301). Eight lipid-markers passed the feature selection and comprised GluCerC16, LPA20:4, HETE15S, LacCerC24:1, C16Sphinganine, biopterin and the endocannabinoids PEA and OEA. A complex classifier or biomarker was developed that predicted MS at a sensitivity, specificity and accuracy of approximately 95% in training and test data sets, respectively. The present successful application of serum lipid marker concentrations to MS data is encouraging for further efforts to establish an MS biomarker based on serum lipidomics.

The relevance of ceramides and their synthesizing enzymes for multiple sclerosis

Ceramide synthases (CerS) synthesize chain length specific ceramides (Cer), which mediate cellular processes in a chain length-dependent manner. In experimental autoimmune encephalomyelitis (EAE), an animal model of multiple sclerosis (MS), we observed that the genetic deletion of CerS2 suppresses EAE pathology by interaction with granulocyte-colony stimulating factor (G-CSF) signaling and CXC motif chemokine receptor 2 (CXCR2) expression, leading to impaired neutrophil migration. In the present study, we investigated the importance of Cers and their synthesizing/metabolizing enzymes in MS. For this purpose, a longitudinal study with 72 MS patients and 25 healthy volunteers was performed. Blood samples were collected from healthy controls and MS patients over 1- or 3-year periods, respectively. Immune cells were counted using flow cytometry, ceramide levels were determined using liquid chromatography-tandem mass spectrometry, and mRNA expression was analyzed using quantitative PCR. In white blood cells, C16-LacCer and C24-Cer were down-regulated in MS patients in comparison with healthy controls. In plasma, C16-Cer, C24:1-Cer, C16-GluCer, and C24:1-GluCer were up-regulated and C16-LacCer was down-regulated in MS patients in comparison with healthy controls. Blood samples from MS patients were characterized by an increased B-cell number. However, there was no correlation between B-cell number and Cer levels. mRNA expression of Cer metabolizing enzymes and G-CSF signaling enzymes was significantly increased in MS patients. Interestingly, G-CSF receptor (G-CSFR) and CXCR2 mRNA expression correlated with CerS2 and UDP-glucose Cer glucosyltransferase (UGCG) mRNA expression. In conclusion, our results indicate that Cer metabolism is linked to G-CSF signaling in MS.