M1-derived extracellular vesicles polarize recipient macrophages into M2-like macrophages and alter skeletal muscle homeostasis in a hyper-glucose environment.

BACKGROUND: Macrophages release not only cytokines but also extracellular vesicles (EVs). which are small membrane-derived nanovesicles with virus-like properties transferring cellular material between cells. Until now, the consequences of macrophage plasticity on the release and the composition of EVs have been poorly explored. In this study, we determined the impact of high-glucose (HG) concentrations on macrophage metabolism, and characterized their derived-EV subpopulations. Finally, we determined whether HG-treated macrophage-derived EVs participate in immune responses and in metabolic alterations of skeletal muscle cells. METHODS: THP1-macrophages were treated with 15mM (MG15) or 30mM (MG30) glucose. Then, M1/M2 canonical markers, pro- and anti-inflammatory cytokines, activities of proteins involved in glycolysis or oxidative phosphorylation were evaluated. Macrophage-derived EVs were characterized by TEM, NTA, MRSP, and 1H-Nuclear magnetic resonance spectroscopy for lipid composition. Macrophages or C2C12 muscle cells were used as recipients of MG15 and MG30-derived EVs. The lipid profiles of recipient cells were determined, as well as proteins and mRNA levels of relevant genes for macrophage polarization or muscle metabolism. RESULTS: Untreated macrophages released small and large EVs (sEVs, lEVs) with different lipid distributions. Proportionally to the glucose concentration, glycolysis was induced in macrophages, associated to mitochondrial dysfunction, triacylglycerol and cholesterol accumulation. In addition, MG15 and MG30 macrophages had increased level of CD86 and increase release of pro-inflammatory cytokines. HG also affected macrophage sphingolipid and phospholipid compositions. The differences in the lipid profiles between sEVs and lEVs were abolished and reflected the lipid alterations in MG15 and MG30 macrophages. Interestingly, MG15 and MG30 macrophages EVs induced the expression of CD163, Il-10 and increased the contents of triacylglycerol and cholesterol in recipient macrophages. MG15 lEVs and sEVs induced insulin-induced AKT hyper-phosphorylation and accumulation of triacylglycerol in myotubes, a state observed in pre-diabetes. Conversely, MG30 lEVs and sEVs induced insulin-resistance in myotubes. CONCLUSIONS: As inflammation involves first M1 macrophages, then the activation of M2 macrophages to resolve inflammation, this study demonstrates that the dialog between macrophages through the EV route is an intrinsic part of the inflammatory response. In a hyperglycemic context, EV macrophages could participate in the development of muscle insulin-resistance and chronic inflammation.

Muscle and Adipose Tissue Communicate with Extracellular Vesicles.

In numerous body locations, muscle and adipose tissue are in close contact. Both tissues are endocrine organs that release cytokines, playing a crutial role in the control of tissue homeostasis in health and diseases. Within this context, the identification of the signals involved in muscle-fat crosstalk has been a hot topic over the last 15 years. Recently, it has been discovered that adipose tissue and muscles can release information embedded in lipid-derived nanovesicles called 'extracellular vesicles' (EVs), which can modulate the phenotype and the homeostasis of neighboring recipient cells. This article reviews knowledge on EVs and their involvement in the communication between adipose tissue and muscle in several body locations. Even if the works are scarce, they have revolutionized our vision in the field of metabolic and cardiovascular diseases.

Adipocyte-Derived Extracellular Vesicles: State of the Art.

White adipose tissue (WAT) is involved in long-term energy storage and represents 10-15% of total body weight in healthy humans. WAT secretes many peptides (adipokines), hormones and steroids involved in its homeostatic role, especially in carbohydrate-lipid metabolism regulation. Recently, adipocyte-derived extracellular vesicles (AdEVs) have been highlighted as important actors of intercellular communication that participate in metabolic responses to control energy flux and immune response. In this review, we focus on the role of AdEVs in the cross-talks between the different cellular types composing WAT with regard to their contribution to WAT homeostasis and metabolic complications development. We also discuss the AdEV cargoes (proteins, lipids, RNAs) which may explain AdEV's biological effects and demonstrate that, in terms of proteins, AdEV has a very specific signature. Finally, we list and suggest potential therapeutic strategies to modulate AdEV release and composition in order to reduce their deleterious effects during the development of metabolic complications associated with obesity.

An APOA5 3' UTR variant associated with plasma triglycerides triggers APOA5 downregulation by creating a functional miR-485-5p binding site.

APOA5 c.*158C>T (rs2266788), located in the 3' UTR, belongs to APOA5 haplotype 2 (APOA5*2), which is strongly associated with plasma triglyceride levels and modulates the occurrence of both moderate and severe hypertriglyceridemia. Individuals with APOA5*2 display reduced APOA5 expression at the posttranscriptional level. However, the functionality of this haplotype remains unclear. We hypothesized that the hypertriglyceridemic effects of APOA5*2 could involve miRNA regulation in the APOA5 3' UTR. Bioinformatic studies have identified the creation of a potential miRNA binding site for liver-expressed miR-485-5p (MIRN485-5p) in the mutant APOA5 3' UTR with the c.*158C allele. In human embryonic kidney 293T (HEK293T) cells cotransfected with an APOA5 3' UTR luciferase reporter vector and a miR485-5p precursor, c.*158C allele expression was significantly decreased. Moreover, in HuH-7 cells endogenously expressing miR-485-5p, we observed that luciferase activity was significantly lower in the presence of the c.*158C allele than in the presence of the c.*158T allele, which was completely reversed by a miR-485-5p inhibitor. We demonstrated that the rare c.*158C APOA5 allele creates a functional target site for liver-expressed miR-485-5p. Therefore, we propose that the well-documented hypertriglyceridemic effect of APOA5*2 involves an APOA5 posttranscriptional downregulation mediated by miR-485-5p.

Exosome-like vesicles released from lipid-induced insulin-resistant muscles modulate gene expression and proliferation of beta recipient cells in mice.

AIMS/HYPOTHESIS: The crosstalk between skeletal muscle (SkM) and beta cells plays a role in diabetes aetiology. In this study, we have investigated whether SkM-released exosome-like vesicles (ELVs) can be taken up by pancreatic beta cells and can deliver functional cargoes. METHODS: Mice were fed for 16 weeks with standard chow diet (SCD) or with standard diet enriched with 20% palmitate (HPD) and ELVs were purified from quadriceps muscle. Fluorescent ELVs from HPD or SCD quadriceps were injected i.v. or intramuscularly (i.m.) into mice to determine their biodistributions. Micro (mi)RNA quantification in ELVs was determined using quantitative real-time RT-PCR (qRT-PCR)-based TaqMan low-density arrays. Microarray analyses were performed to determine whether standard diet ELVs (SD-ELVs) and high palmitate diet ELVs (HPD-ELVs) induced specific transcriptional signatures in MIN6B1 cells. RESULTS: In vivo, muscle ELVs were taken up by pancreas, 24 h post-injection. In vitro, both SD-ELVs and HPD-ELVs transferred proteins and miRNAs to MIN6B1 cells and modulated gene expressions whereas only HPD-ELVs induced proliferation of MIN6B1 cells and isolated islets. Bioinformatic analyses suggested that transferred HPD-ELV miRNAs may participate in these effects. To validate this, we demonstrated that miR-16, which is overexpressed in HPD-ELVs, was transferred to MIN6B1 cells and regulated Ptch1, involved in pancreas development. In vivo, islets from HPD mice showed increased size and altered expression of genes involved in development, including Ptch1, suggesting that the effect of palm oil on islet size in vivo was reproduced in vitro by treating beta cells with HPD-ELVs. CONCLUSIONS/INTERPRETATION: Our data suggest that muscle ELVs might have an endocrine effect and could participate in adaptations in beta cell mass during insulin resistance.

Pathways Implicated in Tadalafil Amelioration of Duchenne Muscular Dystrophy.

Numerous therapeutic approaches for Duchenne and Becker Muscular Dystrophy (DMD and BMD), the most common X-linked muscle degenerative disease, have been proposed. So far, the only one showing a clear beneficial effect is the use of corticosteroids. Recent evidence indicates an improvement of dystrophic cardiac and skeletal muscles in the presence of sustained cGMP levels secondary to a blocking of their degradation by phosphodiesterase five (PDE5). Due to these data, we performed a study to investigate the effect of the specific PDE5 inhibitor, tadalafil, on dystrophic skeletal muscle function. Chronic pharmacological treatment with tadalafil has been carried out in mdx mice. Behavioral and physiological tests, as well as histological and biochemical analyses, confirmed the efficacy of the therapy. We then performed a microarray-based genomic analysis to assess the pattern of gene expression in muscle samples obtained from the different cohorts of animals treated with tadalafil. This scrutiny allowed us to identify several classes of modulated genes. Our results show that PDE5 inhibition can ameliorate dystrophy by acting at different levels. Tadalafil can lead to (1) increased lipid metabolism; (2) a switch towards slow oxidative fibers driven by the up-regulation of PGC-1α; (3) an increased protein synthesis efficiency; (4) a better actin network organization at Z-disk.

Depleting extracellular vesicles from fetal bovine serum alters proliferation and differentiation of skeletal muscle cells in vitro.

BACKGROUND: Fetal bovine serum (FBS) contains a wide range of growth factors, hormones, vitamins, amino acids, fatty acids and trace elements required for cell growth. It was shown that animal sera contain also extracellular vesicles (EVs) with important biological properties; thus we wondered whether EVs present in FBS would influence muscle cell phenotype. EVs were removed from sera by ultracentrifugation (18 h). C2C12, L6 and human primary myoblasts, were grown either in classical media (CM) or in EVs-depleted media. Differentiation was induced by replacing the culture medium either with CM or EV-depleted media. qRT-PCR of relevant genes and miRNA involved in proliferation, differentiation, energy metabolism and EVs formation and secretion were performed. RESULTS: Growth of myoblasts in EV-free media during proliferation produces the most unfavorable situation for proper myotube formation, when considering C212 and human myoblasts. Removing EVs from serum committed myoblasts to differentiate precociously (induction of myogenin and decreased expression of myomiR involved in myogenesis). C2C12 and human myoblasts, grown constantly in EV-depleted media during proliferation and differentiation, formed less myotubes than in CM. They had a reduced level of myogenin and a strong increase in myostatin expression, a negative regulator of muscle cell differentiation that affects myotube size. This situation was not reversed when confluent myoblasts were switched to CM for differentiation. Like C2C12 and human cells, L6 formed less myotubes in EVs-depleted media. However, as they do not express myostatin, L6 myotubes were larger and expressed higher level of CKTM2 compared to myotubes grown in CM suggesting that they had reached a higher level of differentiation. CONCLUSIONS: Researchers studying the role of muscle EVs in culture conditions should consider that depleting EVs from serum alters the phenotype of muscle cells. Interestingly, the cross-talk between myoblasts and myotubes during myogenesis (Forterre 2014, PLoS One. 2014 Jan 2;9(1):e84153) can be recapitulate by using FBS-EVs as well. This implies that EVs can transfer specific signals to cells from unrelated species and that part of serum EV composition is evolutionarily conserved (e.g.; myomiR are detected in FBS-EVs). EVs in body fluids could have an unsuspected function during embryogenesis and in regulation of cellular processes such as hypertrophy and hyperplasia.

Horizontal transfer of exosomal microRNAs transduce apoptotic signals between pancreatic beta-cells.

BACKGROUND: Diabetes mellitus is a common metabolic disorder characterized by dysfunction of insulin-secreting pancreatic beta-cells. MicroRNAs are important regulators of beta-cell activities. These non-coding RNAs have recently been discovered to exert their effects not only inside the cell producing them but, upon exosome-mediated transfer, also in other recipient cells. This novel communication mode remains unexplored in pancreatic beta-cells. In the present study, the microRNA content of exosomes released by beta-cells in physiological and physiopathological conditions was analyzed and the biological impact of their transfer to recipient cells investigated. RESULTS: Exosomes were isolated from the culture media of MIN6B1 and INS-1 derived 832/13 beta-cell lines and from mice, rat or human islets. Global profiling revealed that the microRNAs released in MIN6B1 exosomes do not simply reflect the content of the cells of origin. Indeed, while a subset of microRNAs was preferentially released in exosomes others were selectively retained in the cells. Moreover, exposure of MIN6B1 cells to inflammatory cytokines changed the release of several microRNAs. The dynamics of microRNA secretion and their potential transfer to recipient cells were next investigated. As a proof-of-concept, we demonstrate that if cel-miR-238, a C. Elegans microRNA not present in mammalian cells, is expressed in MIN6B1 cells a fraction of it is released in exosomes and is transferred to recipient beta-cells. Furthermore, incubation of untreated MIN6B1 or mice islet cells in the presence of microRNA-containing exosomes isolated from the culture media of cytokine-treated MIN6B1 cells triggers apoptosis of recipient cells. In contrast, exosomes originating from cells not exposed to cytokines have no impact on cell survival. Apoptosis induced by exosomes produced by cytokine-treated cells was prevented by down-regulation of the microRNA-mediating silencing protein Ago2 in recipient cells, suggesting that the effect is mediated by the non-coding RNAs. CONCLUSIONS: Taken together, our results suggest that beta-cells secrete microRNAs that can be transferred to neighboring beta-cells. Exposure of donor cells to pathophysiological conditions commonly associated with diabetes modifies the release of microRNAs and affects survival of recipient beta-cells. Our results support the concept that exosomal microRNAs transfer constitutes a novel cell-to-cell communication mechanism regulating the activity of pancreatic beta-cells.

Long-standing arterial hypertension is associated with Pitx2 down-regulation in a rat model of spontaneous atrial tachyarrhythmias.

AIMS: The timecourse of left atrial Pitx2 down-regulation in the setting of atrial tachyarrhythmias remains unknown. Accordingly, we aimed to assess the age dependency of left atrial Pitx2 expression in an experimental model of spontaneous atrial tachyarrhythmias in rats. METHODS AND RESULTS: Atrial sampling was performed in three groups (n = 4 each) of young (14-week-old), adult (24-week-old), and ageing (48-week-old) spontaneously hypertensive rats (SHRs), in which we previously demonstrated the age dependency of spontaneous atrial tachyarrhythmias, and three groups (n = 4 each) of age-matched normotensive Wistar-Kyoto (WKY) rats. mRNA expression of Pitx2 was studied using real-time polymerase chain reaction. Ageing SHRs presented significantly lower left atrial Pitx2 expressions compared with age-matched WKY rats (P = 0.02), while no significant difference was observed between young or adult SHRs and age-matched WKY rats (both P > 0.05). Among SHRs, Pitx2 expressions showed a progressive, age-dependent decrease (34.9 ± 6.7 in young SHRs, 17.1 ± 3.6 in adult SHRs, and 10.7 ± 1.7 in ageing SHRs, P = 0.04) and were significantly negatively correlated with both age (Spearman r = -0.86, P < 0.01) and heart weight (Spearman r = -0.76, P < 0.01). CONCLUSION: The present study suggests the presence of age-dependent left atrial Pitx2 down-regulation in SHRs. The strong negative correlation between left atrial Pitx2 expression and heart weight among SHRs may indicate a link between long-standing arterial hypertension and Pitx2-related atrial arrhythmogenicity.

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

AIMS/HYPOTHESIS: Exosomes released from cells can transfer both functional proteins and RNAs between cells. In this study we tested the hypothesis that muscle cells might transmit specific signals during lipid-induced insulin resistance through the exosomal route. METHODS: Exosomes were collected from quadriceps muscles of C57Bl/6 mice fed for 16 weeks with either a standard chow diet (SD) or an SD enriched with 20% palm oil (HP) and from C2C12 cells exposed to 0.5 mmol/l palmitate (EXO-Post Palm), oleate (EXO-Post Oleate) or BSA (EXO-Post BSA). RESULTS: HP-fed mice were obese and insulin resistant and had altered insulin-induced Akt phosphorylation in skeletal muscle (SkM). They also had reduced expression of Myod1 and Myog and increased levels of Ccnd1 mRNA, indicating that palm oil had a deep impact on SkM homeostasis in addition to insulin resistance. HP-fed mouse SkM secreted more exosomes than SD-fed mouse SkM. This was reproduced in-vitro using C2C12 cells pre-treated with palmitate, the most abundant saturated fatty acid of palm oil. Exosomes from HP-fed mice, EXO-Post Palm and EXO-Post Oleate induced myoblast proliferation and modified the expressions of genes involved in the cell cycle and muscle differentiation but did not alter insulin-induced Akt phosphorylation. Lipidomic analyses showed that exosomes from palmitate-treated cells were enriched in palmitate, indicating that exosomes likely transfer the deleterious effect of palm oil between muscle cells by transferring lipids. Muscle exosomes were incorporated into various tissues in vivo, including the pancreas and liver, suggesting that SkM could transfer specific signals through the exosomal route to key metabolic tissues. CONCLUSIONS/INTERPRETATION: Exosomes act as 'paracrine-like' signals and modify muscle homeostasis during high-fat diets.

High-fat diets: You are what you eat .your extracellular vesicles too!

Recent works indicate that the lipid composition of extracellular vesicles (EVs) can modify their biological functions and their incorporation into recipient cells. In particular high-fat diets affect EV biogenesis, EV lipid composition, EV targeting and consequently the cross-talk between tissues. This review connects different research topics to show that a vicious circle is established during the development of high-fat diet-induced obesity, connecting the alteration of lipid metabolism, the composition of extracellular vesicles and the spread of deleterious lipids between tissues, which participates in NAFLD/NASH and diabetes development. According to the studies described in this review, it is urgent to take an interest in this question as the modulation of EV lipid composition could be an important factor to take into account during the therapeutic management of patients suffering from metabolic syndrome and related pathologies such as obesity and diabetes. Furthermore, as lipid modification of EVs is a strategy currently being tested to enable better integration into their target tissue or cell, it is important to consider the impact of these lipid modifications on the homeostasis of these targets.

αv integrin processing interferes with the cross-talk between αvß5/ß6 and α2ß1 integrins.

BACKGROUND INFORMATION: Previous studies have reported that cross-talk between integrins may be an important regulator of integrin-ligand binding and subsequent signalling events that control a variety of cell functions in many tissues. We previously demonstrated that αvß5/ß6 integrin represses α2ß1-dependent cell migration. The αv subunits undergo an endoproteolytic cleavage by protein convertases, whose role in tumoral invasion has remained controversial. RESULTS: Inhibition of convertases by the convertase inhibitor α1-PDX (α1-antitrypsin Portland variant), leading to the cell-surface expression of an uncleaved form of the αv integrin, stimulated cell migration toward type I collagen. Under convertase inhibition, α2ß1 engagement led to enhanced phosphorylation of both FAK (focal adhesion kinase) and MAPK (mitogen-activated protein kinase). This outside-in signalling stimulation was associated with increased levels of activated ß1 integrin located in larger than usual focal-adhesion structures and a cell migration that was independent of the PI3K (phosphoinositide 3-kinase)/Akt (also called protein kinase B) pathway. CONCLUSIONS: The increase in cell migration observed upon convertases inhibition appears to be due to the up-regulation of ß1 integrins and to their location in larger focal-adhesion structures. The endoproteolytic cleavage of αv subunits is necessary for αvß5/ß6 integrin to control α2ß1 function and could thus play an essential role in colon cancer cell migration.

Correction: Blood-derived miRNA levels are not correlated with metabolic or anthropometric parameters in obese pre-diabetic subjects but with systemic inflammation.

[This corrects the article DOI: 10.1371/journal.pone.0263479.].

Blood-derived miRNA levels are not correlated with metabolic or anthropometric parameters in obese pre-diabetic subjects but with systemic inflammation.

As blood-derived miRNAs (c-miRNAs) are modulated by exercise and nutrition, we postulated that they might be used to monitor the effects of a lifestyle intervention (LI) to prevent diabetes development. To challenge this hypothesis, obese Asian Indian pre-diabetic patients were submitted to diet modifications and physical activity for 4 months (LI group) and compared to a control group which was given recommendations only. We have considered 2 periods of time to analyze the data, i.e.; a first one to study the response to the intervention (4 months), and a second one post-intervention (8 months). At basal, 4 months and 8 months post-intervention the levels of 17 c-miRNAs were quantified, selected either for their relevance to the pathology or because they are known to be modulated by physical activity or diet. Their variations were correlated with variations of 25 metabolic and anthropometric parameters and cytokines. As expected, fasting-glycaemia, insulin-sensitivity, levels of exercise- and obesity-induced cytokines were ameliorated after 4 months. In addition, the levels of 4 miRNAs (i.e.; miR-128-3p, miR-374a-5p, miR-221-3p, and miR-133a-3p) were changed only in the LI group and were correlated with metabolic improvement (insulin sensitivity, cytokine levels, waist circumference and systolic blood pressure). However, 8 months post-intervention almost all ameliorated metabolic parameters declined indicating that the volunteers did not continue the protocol on their own. Surprisingly, the LI positive effects on c-miRNA levels were still detected, and were even more pronounced 8 months post-intervention. In parallel, MCP-1, involved in tissue infiltration by immune cells, and Il-6, adiponectin and irisin, which have anti-inflammatory effects, continued to be significantly and positively modified, 8 months post-intervention. These data demonstrated for the first time, that c-miRNA correlations with metabolic parameters and insulin sensitivity are in fact only indirect and likely associated with the level systemic inflammation. More generally speaking, this important result explains the high variability between the previous studies designed to identify specific c-miRNAs associated with the severity of insulin-resistance. The results of all these studies should take into account the level of inflammation of the patients. In addition, this finding could also explain why, whatever the pathology considered (i.e.; cancers, diabetes, neurodegenerative disorders, inflammatory diseases) the same subset of miRNAs is always found altered in the blood of patients vs healthy subjects, as these pathologies are all associated with the development of inflammation.

Adipocyte-derived extracellular vesicles in health and diseases: Nano-packages with vast biological properties.

As the largest human energy reservoir, adipocytes drive an intense dialog with other cells/organs throughout the body to regulate the size of adipose tissue and to communicate with other metabolic tissues and the brain to regulate energy supply. Adipokines have long been described as mediators of this crosstalk, participating in obesity-associated complications. Recently, adipocyte-derived extracellular vesicles (Ad-EVs) have emerged as new key actors in this communication due to their powerful capacity to convey complex messages between cells. Ad-EVs convey specific subpopulations of RNA, proteins, and lipids from their parental cells, and can transfer these cargoes into various recipient cells, modulating their metabolism and cell cycle. In healthy individuals, Ad-EVs actively participate in adipose tissue remodeling to compensate energy supply variations by exchanging information between adipocytes or stroma-vascular cells, including immune cells. Besides this, recent evidence points out that Ad-EV secretion and composition from dysfunctional adipocytes are strongly impacted within adipose tissue where they modulate local intercellular communication, contributing to inflammation, fibrosis, abnormal angiogenesis, and at distance with other cells/tissues intrinsically linked to fat (muscle, hepatocytes and even cancer cells). Additionally, some data even suggests that Ad-EVs might have a systemic action. In this review, we will describe the particular properties of Ad-EVs and their involvement in health and diseases, with a particular focus on metabolic and cardiovascular diseases as well as cancer.

Epigenetics in atrial fibrillation: A reappraisal.

Atrial fibrillation (AF) is the most common cardiac arrhythmia and an important cause of morbidity and mortality globally. Atrial remodeling includes changes in ion channel expression and function, structural alterations, and neural remodeling, which create an arrhythmogenic milieu resulting in AF initiation and maintenance. Current therapeutic strategies for AF involving ablation and antiarrhythmic drugs are associated with relatively high recurrence and proarrhythmic side effects, respectively. Over the last 2 decades, in an effort to overcome these issues, research has sought to identify the genetic basis for AF thereby gaining insight into the regulatory mechanisms governing its pathophysiology. Despite identification of multiple gene loci associated with AF, thus far none has led to a therapy, indicating additional contributors to pathology. Recently, in the context of expanding knowledge of the epigenome (DNA methylation, histone modifications, and noncoding RNAs), its potential involvement in the onset and progression of AF pathophysiology has started to emerge. Probing the role of various epigenetic mechanisms that contribute to AF may improve our knowledge of this complex disease, identify potential therapeutic targets, and facilitate targeted therapies. Here, we provide a comprehensive review of growing epigenetic features involved in AF pathogenesis and summarize the emerging epigenomic targets for therapy that have been explored in preclinical models of AF.

Genetic Exchange of Lung-Derived Exosome to Brain Causing Neuronal Changes on COVID-19 Infection.

The pandemic of novel coronavirus 2 (SARS-CoV-2) has made global chaos for normal human living. Despite common COVID-19 symptoms, variability in clinical phenotypes was reported worldwide. Reports on SARS-CoV-2 suggest causing neurological manifestation. In addition, the susceptibility of SARS-CoV-2 in patients with neurodegenerative diseases and its complexity are largely unclear. Here, we aimed to demonstrate the possible transport of exosome from SARS-CoV-2-infected lungs to the brain regions associated with neurodegenerative diseases using multiple transcriptome datasets of SARS-CoV-2-infected lungs, RNA profiles from lung exosome, and gene expression profiles of the human brain. Upon transport, the transcription factors localized in the exosome regulate genes at lateral substantia nigra, medial substantia nigra, and superior frontal gyrus regions of Parkinson's disease (PD) and frontal cortex, hippocampus, and temporal cortex of Alzheimer's disease (AD). On SARS-CoV-2 infection, BCL3, JUND, MXD1, IRF2, IRF9, and STAT1 transcription factors in the exosomes influence the neuronal gene regulatory network and accelerate neurodegeneration. STAT1 transcription factor regulates 64 PD genes at lateral substantia nigra, 65 at superior frontal gyrus, and 19 at medial substantia nigra. Similarly, in AD, STAT1 regulates 74 AD genes at the temporal cortex, 40 genes at the hippocampus, and 16 genes at the frontal cortex. We further demonstrate that dysregulated neuronal genes showed involvement in immune response, signal transduction, apoptosis, and stress response process. In conclusion, SARS-CoV-2 may dysregulate neuronal gene regulatory network through exosomes that attenuate disease severity of neurodegeneration.

Profiling of ob/ob mice skeletal muscle exosome-like vesicles demonstrates combined action of miRNAs, proteins and lipids to modulate lipid homeostasis in recipient cells.

We have determined the lipid, protein and miRNA composition of skeletal muscle (SkM)-released extracellular vesicles (ELVs) from Ob/ob (OB) vs wild-type (WT) mice. The results showed that atrophic insulin-resistant OB-SkM released less ELVs than WT-SkM, highlighted by a RAB35 decrease and an increase in intramuscular cholesterol content. Proteomic analyses of OB-ELVs revealed a group of 37 proteins functionally connected, involved in lipid oxidation and with catalytic activities. OB-ELVs had modified contents for phosphatidylcholine (PC 34-4, PC 40-3 and PC 34-0), sphingomyelin (Sm d18:1/18:1) and ceramides (Cer d18:1/18:0) and were enriched in cholesterol, likely to alleviated intracellular accumulation. Surprisingly many ELV miRNAs had a nuclear addressing sequence, and targeted genes encoding proteins with nuclear activities. Interestingly, SkM-ELV miRNA did not target mitochondria. The most significant function targeted by the 7 miRNAs altered in OB-ELVs was lipid metabolism. In agreement, OB-ELVs induced lipid storage in recipient adipocytes and increased lipid up-take and fatty acid oxidation in recipient muscle cells. In addition, OB-ELVs altered insulin-sensitivity and induced atrophy in muscle cells, reproducing the phenotype of the releasing OB muscles. These data suggest for the first time, a cross-talk between muscle cells and adipocytes, through the SkM-ELV route, in favor of adipose tissue expansion.

Updating MISEV: Evolving the minimal requirements for studies of extracellular vesicles.

The minimal information for studies of extracellular vesicles (EVs, MISEV) is a field-consensus rigour initiative of the International Society for Extracellular Vesicles (ISEV). The last update to MISEV, MISEV2018, was informed by input from more than 400 scientists and made recommendations in the six broad topics of EV nomenclature, sample collection and pre-processing, EV separation and concentration, characterization, functional studies, and reporting requirements/exceptions. To gather opinions on MISEV and ideas for new updates, the ISEV Board of Directors canvassed previous MISEV authors and society members. Here, we share conclusions that are relevant to the ongoing evolution of the MISEV initiative and other ISEV rigour and standardization efforts.

Analysis of lifestyle and metabolic predictors of visceral obesity with Bayesian Networks.

BACKGROUND: The aim of this study was to provide a framework for the analysis of visceral obesity and its determinants in women, where complex inter-relationships are observed among lifestyle, nutritional and metabolic predictors. Thirty-four predictors related to lifestyle, adiposity, body fat distribution, blood lipids and adipocyte sizes have been considered as potential correlates of visceral obesity in women. To properly address the difficulties in managing such interactions given our limited sample of 150 women, bootstrapped Bayesian networks were constructed based on novel constraint-based learning methods that appeared recently in the statistical learning community. Statistical significance of edge strengths was evaluated and the less reliable edges were pruned to increase the network robustness. To allow accessible interpretation and integrate biological knowledge into the final network, several undirected edges were afterwards directed with physiological expertise according to relevant literature. RESULTS: Extensive experiments on synthetic data sampled from a known Bayesian network show that the algorithm, called Recursive Hybrid Parents and Children (RHPC), outperforms state-of-the-art algorithms that appeared in the recent literature. Regarding biological plausibility, we found that the inference results obtained with the proposed method were in excellent agreement with biological knowledge. For example, these analyses indicated that visceral adipose tissue accumulation is strongly related to blood lipid alterations independent of overall obesity level. CONCLUSIONS: Bayesian Networks are a useful tool for investigating and summarizing evidence when complex relationships exist among predictors, in particular, as in the case of multifactorial conditions like visceral obesity, when there is a concurrent incidence for several variables, interacting in a complex manner. The source code and the data sets used for the empirical tests are available at http://www710.univ-lyon1.fr/~aaussem/Software.html.