Human adipocyte extracellular vesicles in reciprocal signaling between adipocytes and macrophages

Secretion of miRNA-326-3p by senescent adipose exacerbates myocardial metabolism in diabetic mice

BACKGROUND

Adipose tissue homeostasis is at the heart of many metabolic syndromes such as diabetes. Previously it has been demonstrated that adipose tissues from diabetic patients are senescent but whether this contributes to diabetic cardiomyopathy (DCM) remains to be elucidated.

METHODS

The streptozotocin (STZ) type 1 diabetic mice were established as animal model, and adult mouse ventricular myocytes (AMVMs) isolated by langendorff perfusion as well as neonatal mouse ventricular myocytes (NMVMs) were used as cell models. Senescent associated β galactosidase (SA-β-gal) staining and RT-qPCR were used to identify the presence of adipose senescence in diabetic adipose tissue. Senescent adipose were removed either by surgery or by senolytic treatment. Large extracellular vesicles (LEVs) derived from adipose tissue and circulation were separated by ultracentrifugation. Cardiac systolic and diastolic function was evaluated through cardiac ultrasound. Cardiomyocytes contraction function was evaluated by the Ionoptix HTS system and live cell imaging, mitochondrial morphology and functions were evaluated by transmission electron microscope, live cell fluorescent probe and seahorse analysis. RNA-seq for AMVMs and miRNA-seq for LEVs were performed, and bioinformatic analysis combined with RT-qPCR and Western blot were used to elucidate underlying mechanism that senescent adipose derives LEVs exacerbates myocardial metabolism.

RESULTS

SA-β-gal staining and RT-qPCR identified the presence of adipose tissue senescence in STZ mice. Through surgical as well as pharmacological means we show that senescent adipose tissue participates in the pathogenesis of DCM in STZ mice by exacerbates myocardial metabolism through secretion of LEVs. Specifically, expression of miRNA-326-3p was up-regulated in LEVs isolated from senescent adipose tissue, circulation, and cardiomyocytes of STZ mice. Up-regulation of miRNA-326-3p coincided with myocardial transcriptomic changes in metabolism. Functionally, we demonstrate that miRNA-326-3p inhibited the expression of Rictor and resulted in impaired mitochondrial and contractile function in cardiomyocytes.

CONCLUSION

We demonstrate for the first time that senescent adipose derived LEVs exacerbates myocardial metabolism through up-regulated miRNA-326-3p which inhibits Rictor in cardiomyocytes. Furthermore, reducing senescence burden in adipose tissue is capable of relieving myocardial metabolism disorder in diabetes mellitus.

The challenges of interrogating adipose tissue extracellular vesicle functions in physiology

Recent developments in adipose tissue-derived extracellular vesicle (EV) research is highlighted, assessing current adipose tissue EV research strategies and obstacles the field faces.

Extracellular Vesicles from Adipose Tissue Could Promote Metabolic Adaptation through PI3K/Akt/mTOR

Extracellular vesicles (EVs) are nanoparticles secreted by cells under physiological and pathological conditions, such as metabolic diseases. In this context, EVs are considered potential key mediators in the physiopathology of obesity. It has been reported that EVs derived from adipose tissue (ADEVs) contribute to the development of a local inflammatory response that leads to adipose tissue dysfunction. In addition, it has been proposed that EVs are associated with the onset and progression of several obesity-related metabolic diseases such as insulin resistance. In particular, characterizing the molecular fingerprint of obesity-related ADEVs can provide a bigger picture that better reflects metabolic adaptation though PI3K/Akt/mTOR. Hence, in this review we describe the possible crosstalk communication of ADEVs with metabolically active organs and the intracellular response in the insulin signaling pathway.

Extracellular Vesicles and Their Emerging Roles as Cellular Messengers in Endocrinology: An Endocrine Society Scientific Statement

During the last decade, there has been great interest in elucidating the biological role of extracellular vesicles (EVs), particularly, their hormone-like role in cell-to-cell communication. The field of endocrinology is uniquely placed to provide insight into the functions of EVs, which are secreted from all cells into biological fluids and carry endocrine signals to engage in paracellular and distal interactions. EVs are a heterogeneous population of membrane-bound vesicles of varying size, content, and bioactivity. EVs are specifically packaged with signaling molecules, including lipids, proteins, and nucleic acids, and are released via exocytosis into biofluid compartments. EVs regulate the activity of both proximal and distal target cells, including translational activity, metabolism, growth, and development. As such, EVs signaling represents an integral pathway mediating intercellular communication. Moreover, as the content of EVs is cell-type specific, it is a "fingerprint" of the releasing cell and its metabolic status. Recently, changes in the profile of EV and bioactivity have been described in several endocrine-related conditions including diabetes, obesity, cardiovascular diseases, and cancer. The goal of this statement is to highlight relevant aspects of EV research and their potential role in the field of endocrinology.

A New Protocol to Treat Abdominal Subcutaneous Fat Combining Microwaves and Flat magnetic stimulation

Background: A healthy lifestyle is not always able to improve the abdomen’s appearance, especially in those patients who have undergone sudden weight changes. Objective: We aimed at evaluating the efficacy of combined microwaves and flat magnetic stimulation (FMS) to treat abdominal localized adiposity and laxity. Methods: Twenty-five patients were subjected to two treatment sessions per month on the abdominal area with microwaves. FMS was also performed twice per week, with a minimum of two days between each session for two months. The technology uses three types of different protocols: massage, muscle definition (shaping), and muscular strengthening. Measurements, including body mass index (BMI) and waist, and abdominal ultrasound were performed at baseline and three months after the last treatment session. Blood examinations were performed, and a 5-Likert scale questionnaire was used to assess patient satisfaction. Results: At follow-up, three months after the last treatment, the mean waist circumference (WC) was significantly reduced, and skin laxity improved in all patients (p < 0.001). A significant improvement in abdominal muscle tissue thickness was also shown in all abdominal areas, and the thickness of the adipose tissue evaluated by ultrasound was reduced. Conclusions: This study proves that the combination of microwaves and FMS treatment is secure and efficient for treating abdominal subcutaneous fat and skin laxity.

Adipose-Derived Extracellular Vesicles: Systemic Messengers and Metabolic Regulators in Health and Disease

Adipose tissue is comprised of a heterogeneous population of cells that co-operate to perform diverse physiological roles including endocrine-related functions. The endocrine role of adipose tissue enables it to communicate nutritional and health cues to other organs, such as the liver, muscle, and brain, in order to regulate appetite and whole body metabolism. Adipose tissue dysfunction, which is often observed in obesity, is associated with changes in the adipose secretome, which can subsequently contribute to disease pathology. Indeed, secreted bioactive factors released from adipose tissue contribute to metabolic homeostasis and likely play a causal role in disease; however, what constitutes the entirety of the adipose tissue secretome is still poorly understood. Recent advances in nanotechnology have advanced this field substantially and have led to the identification of small, secreted particles known as extracellular vesicles (EVs). These small nano-sized lipid envelopes are released by most cell types and are capable of systemically delivering bioactive molecules, such as nucleic acids, proteins, and lipids. EVs interact with target cells to deliver specific cargo that can then elicit effects in various tissues throughout the body. Adipose tissue has recently been shown to secrete EVs that can communicate with the periphery to maintain metabolic homeostasis, or under certain pathological conditions, drive disease. In this review, we discuss the current landscape of adipose tissue-derived EVs, with a focus on their role in the regulation of metabolic homeostasis and disease pathology.

The microenvironment‐ a general hypothesis on the homeostatic function of extracellular vesicles

Extracellular vesicles (EVs), exosomes and microvesicles, is a burgeoning field of biological and biomedical research that may change our understanding of cell communication in plants and animals while holding great promise for the diagnosis of disease and the development of therapeutics. However, the challenge remains to develop a general hypothesis about the role of EVs in physiological homeostasis and pathobiology across kingdoms. While they can act systemically, EVs are often seen to operate locally within a microenvironment. This microenvironment is built as a collection of microunits comprised of cells that interact with each other via EV exchange, EV signaling, EV seeding, and EV disposal. We propose that microunits are part of a larger matrix at the tissue level that collectively communicates with the surrounding environment, including other end‐organ systems. Herein, we offer a working model that encompasses the various facets of EV function in the context of the cell biology and physiology of multicellular organisms.

Intercellular and interorgan crosstalk through adipocyte extracellular vesicles

Functional adipose tissue is essential for homeostatic maintenance of systemic metabolism. As such, adipose tissue dysfunction, like that seen in the obese state, directly contributes to system-wide pathological metabolism, leading to the development of type 2 diabetes and other obesity-associated comorbidities. In addition to the storage function of adipocytes, they also secrete numerous factors that robustly regulate metabolism-related pathways throughout the body. Many of these factors, in addition to other signaling proteins, RNA species and lipids, are found in extracellular vesicles (EVs) released from adipocytes. EVs are vesicles with a lipid bilayer, known to carry signaling proteins and lipids, mRNAs and miRNAs. Because of this diverse cargo, EVs can have robust and pleotropic signaling effects depending on the receiving target cells. We are only now starting to understand how adipocyte EVs can modulate metabolism within adipose tissue and beyond. Here, we highlight the current literature that demonstrates EV-mediated crosstalk between adipocytes and other tissues or distal cells. We become increasingly aware of the importance of these adipocyte-derived EV signals that establish a so far underappreciated endocrine system. Adipocyte EVs offer a new avenue for pharmacological manipulation of metabolism to treat obesity-related disease.

Noncoding RNAs from tissue-derived small extracellular vesicles: Roles in diabetes and diabetic complications

Diabetes is a systemic disease, and its progression involves multiple organ dysfunction. However, the exact mechanisms underlying pathological progression remain unclear. Small extracellular vesicles (sEVs) mediate physiological and pathological signaling communication between organs and have been shown to have important regulatory roles in diabetes and its complications in recent years. In particular, the majority of studies in the diabetes-related research field have focused on the noncoding RNAs carried by sEVs. Researchers found that noncoding RNA sorting into sEVs is not random but selective. Both tissue origin differences and environmental variations affect the cargo of sEVs. In addition, the function of sEVs differs according to the tissue they derive from; for example, sEVs derived from adipose tissue regulate insulin sensitivity in the periphery, while sEVs derived from bone marrow promote β-cell regeneration. Therefore, understanding the roles of sEVs from different tissues is important for elucidating their molecular mechanisms and is necessary for the application of sEVs as therapeutic agents for diabetes treatment in the future. In this review, we summarized current studies on the mechanisms of noncoding RNA sorting into sEVs, as well as the research progress on the effects of sEVs from different tissue origins and noncoding RNAs in diabetes and diabetic complications. The knowledge of noncoding RNAs in sEVs will help us better understand the role of sEVs in the diabetes progression.

Differential expression of aerobic oxidative metabolism-related proteins in diabetic urinary exosomes

BACKGROUND

As a metabolic disease, any abnormality in the aerobic oxidation pathway of glucose may lead to the occurrence of diabetes. This study aimed to investigate the changes in proteins related to aerobic oxidative metabolism in urinary exosomes of diabetic patients and normal controls of different ages, and to further verify their correlation with the pathogenesis of diabetes.

METHODS

Samples were collected, and proteomic information of urinary exosomes was collected by LC-MS/MS. ELISA was used to further detect the expression of aerobic and oxidative metabolism-related proteins in urinary exosomes of diabetic patients and normal controls of different ages, and to draw receiver operating characteristic (ROC) curve to evaluate its value in diabetes monitoring.

RESULTS

A total of 17 proteins involved in aerobic oxidative metabolism of glucose were identified in urinary exosome proteins. Compared with normal control, the expressions of PFKM, GAPDH, ACO2 and MDH2 in diabetic patients were decreased, and the expression of IDH3G was increased. The concentrations of PFKM, GAPDH and ACO2 in urinary exosomes were linearly correlated with the expression of MDH2 (P<0.05). These four proteins vary with age, with the maximum concentration in the 45-59 age group. PFKM, GAPDH, ACO2, and MDH2 in urinary exosomes have certain monitoring value. When used in combination, the AUC was 0.840 (95% CI 0.764-0.915).

CONCLUSIONS

In diabetic patients, aerobic oxidative metabolism is reduced, and the expression of aerobic oxidative metabolism-related proteins PFKM, GAPDH, ACO2, and MDH2 in urinary exosomes is reduced, which may become potential biomarkers for monitoring changes in diabetes.

Human obese white adipose tissue sheds depot-specific extracellular vesicles and reveals candidate biomarkers for monitoring obesity and its comorbidities

Extracellular vesicles (EVs) have been recently postulated as key players in metabolic disorders emerging as an alternative way of paracrine/endocrine communication. However, the nature of EVs shed by adipose tissue (AT) and their role in obesity is still very limited. Here, we isolated human morbid obese visceral (VAT) and subcutaneous (SAT) whole AT shed EVs from donors submitted to bariatric surgery to characterize their protein cargo by qualitative and quantitative/SWATH mass spectrometry analysis. We identified 574 different proteins shed by morbid obese VAT and 401 proteins in those from SAT, establishing the first obese AT EV proteome reference map. Only 50% of identified proteins in VAT vesicles were common to those in SAT; additionally, EVs shed by obese VAT showed more AT and obesity-related adipokines than SAT. Functional classification shows that obese VAT vesicles exhibit an enrichment of proteins implicated in AT inflammation and insulin resistance such as TGFBI, CAVN1, CD14, mimecan, thrombospondin-1, FABP-4 or AHNAK. Selected candidate biomarkers from the quantitative-SWATH analysis were validated in EVs from independent morbid obese and from moderate obese to lean individuals showing that morbid obese VAT vesicles are characterized by a diminution of syntenin 1 and the elevation of TGFBI and mimecan. Interestingly, TGFBI and mimecan containing vesicles could be detected and quantified at circulating level in plasma. Thus, a significant elevation of -TGFBI-EVs was detected on those obese patients with a history of T2D compared to nondiabetic, and an augmentation of mimecan-EVs in obese plasma compared to those in healthy lean individuals. Thus, we conclude that obese AT release functional EVs carrying AT and obesity candidate biomarkers which vary regarding the AT of origin. Our findings suggest that circulating EV-TGFBI may facilitate monitoring T2D status in obese patients, and EV-mimecan may be useful to track adiposity, and more precisely, visceral obesity.

Extracellular vesicles in obesity and its associated inflammation

Obesity is characterized by low-grade, chronic inflammation, which promotes insulin resistance and diabetes. Obesity can lead to the development and progression of many autoimmune diseases, including inflammatory bowel disease, psoriasis, psoriatic arthritis, rheumatoid arthritis, thyroid autoimmunity, and type 1 diabetes mellitus (T1DM). These diseases result from an alteration of self-tolerance by promoting pro-inflammatory immune response by lowering numbers of regulatory T cells (T_regs), increasing Th1 and Th17 immune responses, and inflammatory cytokine production. Therefore, understanding the immunological changes that lead to this low-grade inflammatory milieu becomes crucial for the development of therapies that suppress the risk of autoimmune diseases and other immunological conditions. Cells generate extracellular vesicles (EVs) to eliminate cellular waste as well as communicating the adjacent and distant cells through exchanging the components (genetic material [DNA or RNA], lipids, and proteins) between them. Immune cells and adipocytes from individuals with obesity and a high basal metabolic index (BMI) produce also release exosomes (EXOs) and microvesicles (MVs), which are collectively called EVs. These EVs play a crucial role in the development of autoimmune diseases. The current review discusses the immunological dysregulation that leads to inflammation, inflammatory diseases associated with obesity, and the role played by EXOs and MVs in the induction and progression of this devastating conditi8on.

Extracellular Vesicles in Musculoskeletal Regeneration: Modulating the Therapy of the Future

Tissue regeneration is a hot topic in health sciences, particularly because effective therapies promoting the healing of several cell types are lacking, specifically those of the musculoskeletal system. Mesenchymal Stem/Stromal Cells (MSCs) have been identified as crucial players in bone homeostasis, and are considered a promising therapy for diseases such as osteoarthritis (OA) and Rheumatoid Arthritis (RA). However, some known drawbacks limit their use, particularly ethical issues and immunological rejections. Thus, MSCs byproducts, namely Extracellular Vesicles (EVs), are emerging as potential solutions to overcome some of the issues of the original cells. EVs can be modulated by either cellular preconditioning or vesicle engineering, and thus represent a plastic tool to be implemented in regenerative medicine. Further, the use of biomaterials is important to improve EV delivery and indirectly to modulate their content and secretion. This review aims to connect the dots among MSCs, EVs, and biomaterials, in the context of musculoskeletal diseases.

[Extracellular vesicles and metabolic diseases: Dangerous liaisons]

Extracellular vesicles (EVs) correspond to a heterogeneous set of membrane nanovesicles secreted in the extracellular medium and circulating in the various fluids of the body. These EVs convey biological material (proteins, lipids, nucleic acids) that they can transfer to target cells/tissues thus modulating their response and/or phenotype. The metabolic dysfunctions characterizing metabolic diseases associated with obesity are associated with changes in circulating EV concentrations as well as alterations in their content. The growing interest in EVs as new vectors of intercellular communication has led to question about their role in the development of metabolic complications. In this review, we will discuss the literature on circulating EVs as potential markers of metabolic diseases and then detail inter-organ dialogue based on this EV trafficking underlying the development of related obesity. Finally, we will discuss future avenues of research that will help to better understand the link between EVs and metabolic diseases.

An Exploration of Non-Coding RNAs in Extracellular Vesicles Delivered by Swine Anterior Pituitary

Extracellular vesicles are lipid bilayer-delimited particles carrying proteins, lipids, and small RNAs. Previous studies have demonstrated that they had regulatory functions both physiologically and pathologically. However, information remains inadequate on extracellular vesicles from the anterior pituitary, a key endocrine organ in animals and humans. In this study, we separated and identified extracellular vesicles from the anterior pituitary of the Duroc swine model. Total RNA was extracted and RNA-seq was performed, followed by a comprehensive analysis of miRNAs, lncRNAs, and circRNAs. Resultantly, we obtained 416 miRNAs, 16,232 lncRNAs, and 495 circRNAs. Furthermore, GO and KEGG enrichment analysis showed that the ncRNAs in extracellular vesicles may participate in regulating intracellular signal transduction, cellular component organization or biogenesis, small molecule binding, and transferase activity. The cross-talk between them also suggested that they may play an important role in the signaling process and biological regulation. This is the first report of ncRNA data in the anterior pituitary extracellular vesicles from the duroc swine breed, which is a fundamental resource for exploring detailed functions of extracellular vesicles from the anterior pituitary.

A validated analysis pipeline for mass spectrometry-based vitreous proteomics: new insights into proliferative diabetic retinopathy

Background

Vitreous is an accessible, information-rich biofluid that has recently been studied as a source of retinal disease-related proteins and pathways. However, the number of samples required to confidently identify perturbed pathways remains unknown. In order to confidently identify these pathways, power analysis must be performed to determine the number of samples required, and sample preparation and analysis must be rigorously defined.

Methods

Control (n = 27) and proliferative diabetic retinopathy (n = 23) vitreous samples were treated as biologically distinct individuals or pooled together and aliquoted into technical replicates. Quantitative mass spectrometry with tandem mass tag labeling was used to identify proteins in individual or pooled control samples to determine technical and biological variability. To determine effect size and perform power analysis, control and proliferative diabetic retinopathy samples were analyzed across four 10-plexes. Pooled samples were used to normalize the data across plexes and generate a single data matrix for downstream analysis.

Results

The total number of unique proteins identified was 1152 in experiment 1, 989 of which were measured in all samples. In experiment 2, 1191 proteins were identified, 727 of which were measured across all samples in all plexes. Data are available via ProteomeXchange with identifier PXD025986. Spearman correlations of protein abundance estimations revealed minimal technical (0.99–1.00) and biological (0.94–0.98) variability. Each plex contained two unique pooled samples: one for normalizing across each 10-plex, and one to internally validate the normalization algorithm. Spearman correlation of the validation pool following normalization was 0.86–0.90. Principal component analysis revealed stratification of samples by disease and not by plex. Subsequent differential expression and pathway analyses demonstrated significant activation of metabolic pathways and inhibition of neuroprotective pathways in proliferative diabetic retinopathy samples relative to controls.

Conclusions

This study demonstrates a feasible, rigorous, and scalable method that can be applied to future proteomic studies of vitreous and identifies previously unrecognized metabolic pathways that advance understanding of diabetic retinopathy.

Supplementary Information

The online version contains supplementary material available at 10.1186/s12014-021-09328-8.

Roles and mechanisms of exosomal non-coding RNAs in human health and diseases

Exosomes play a role as mediators of cell-to-cell communication, thus exhibiting pleiotropic activities to homeostasis regulation. Exosomal non-coding RNAs (ncRNAs), mainly microRNAs (miRNAs), long non-coding RNAs (lncRNAs), and circular RNAs (circRNAs), are closely related to a variety of biological and functional aspects of human health. When the exosomal ncRNAs undergo tissue-specific changes due to diverse internal or external disorders, they can cause tissue dysfunction, aging, and diseases. In this review, we comprehensively discuss the underlying regulatory mechanisms of exosomes in human diseases. In addition, we explore the current knowledge on the roles of exosomal miRNAs, lncRNAs, and circRNAs in human health and diseases, including cancers, metabolic diseases, neurodegenerative diseases, cardiovascular diseases, autoimmune diseases, and infectious diseases, to determine their potential implication in biomarker identification and therapeutic exploration.

Diagnostic and Therapeutic Potential of Extracellular Vesicles

Extracellular vesicles (EVs) are naturally phospholipid enclosed nanovesicles released by many cells in the body. They are stable in circulation, have low immunogenicity, and act as carriers for functionally active biological molecules. They interact with target organs and bind to the receptors. Their target specificity is important to use EVs as noninvasive diagnostic and prognostic tools. EVs play a vital role in normal physiology and cellular communication. They are known to protect their cargo from degradation, which makes them important drug carriers for targeted drug delivery. Using EVs with markers and tracking their path in systemic circulation can be revolutionary in using them as diagnostic tools. We will discuss the scope of this in this paper. Although there are limitations in EVs isolation and storage, their high biocompatibility will fuel more innovations to overcome these challenges.

Exosomes Derived From Human Adipose-Derived Stem Cells Inhibit Lipogenesis Involving Hedgehog Signaling Pathway

Since obesity impairs wound closure and adipose-derived exosomes (ADEs) regulate wound healing in clinical applications, we hypothesized that ADEs may inhibit adipogenesis of adipose-derived stem cells (ADSCs) to reduce the adverse effects of obesity on wound healing. Hedgehog (Hh) signaling has been previously shown to inhibit adipogenesis in ADSCs. The present study aimed to determine the role of ADEs in the adipogenesis of ADSCs and the Hh signaling pathway. ADSCs collected from human adipose tissues were co-cultured with ADEs and treated with an adipogenic inducer. qRT-PCR showed that ADEs could inhibit adipogenic differentiation of ADSCs and activate Hh signaling. The differences in the mRNA expression profiles of genes related to Hh signaling between the groups that were exposed to either high fat or low fat indicated that increased Hh signaling activation is necessary but not sufficient to inhibit adipogenic differentiation in the ADSC differentiation process. The Hh signaling pathway can be activated effectively by ADEs, especially during high-fat exposure after treatment with ADEs. Oil Red O staining of adipocytes suggested that ADEs inhibited not only adipogenic differentiation, but also lipogenesis in ADSCs. Overall, targeted activation of Hh signaling by ADEs reduced lipid accumulation in ADSCs and may be explored for clinical applications.

Extracellular vesicle-based interorgan transport of mitochondria from energetically stressed adipocytes

Adipocytes undergo intense energetic stress in obesity resulting in loss of mitochondrial mass and function. We have found that adipocytes respond to mitochondrial stress by rapidly and robustly releasing small extracellular vesicles (sEVs). These sEVs contain respiration-competent, but oxidatively damaged mitochondrial particles, which enter circulation and are taken up by cardiomyocytes, where they trigger a burst of ROS. The result is compensatory antioxidant signaling in the heart that protects cardiomyocytes from acute oxidative stress, consistent with a preconditioning paradigm. As such, a single injection of sEVs from energetically stressed adipocytes limits cardiac ischemia/reperfusion injury in mice. This study provides the first description of functional mitochondrial transfer between tissues and the first vertebrate example of "inter-organ mitohormesis." Thus, these seemingly toxic adipocyte sEVs may provide a physiological avenue of potent cardio-protection against the inevitable lipotoxic or ischemic stresses elicited by obesity.

Role of adipocyte-derived extracellular vesicles in vascular inflammation

Extracellular vesicles (EVs) are nanometre-sized vesicles released from most cells, including adipocytes. Relatively little is known about adipocyte-derived EVs (ADEVs) in comparison to other EV subtypes, though interest in ADEVs as potential paracrine and endocrine communicators of adipose tissue in obesity is building. Current evidence indicates that ADEVs contribute to the development of adipose tissue dysfunction; a key feature of obese adipose tissue that it is associated with obesity-related comorbidities including cardiovascular disease (CVD). This review summarises our current knowledge of ADEVs in the development of adipose tissue dysfunction and the potential of ADEVs to disrupt redox signalling and exert vascular effects that may exacerbate CVD in obesity.

Contribution of the Microbiota and their Secretory Products to Inflammation and Colorectal Cancer Pathogenesis: The Role of Toll-like Receptors

Alterations in diversity and function of the gut microbiome are associated with concomitant changes in immune response, including chronic inflammation. Chronic inflammation is a major risk factor for colorectal cancer (CRC). An important component of the inflammatory response system are the toll-like receptors (TLRs). TLRs are capable of sensing microbial components, including nucleic acids, lipopolysaccharides, and peptidoglycans, as well as bacterial outer membrane vesicles (OMV). OMVs can be decorated with or carry as cargo these TLR activating factors. These microbial factors can either promote tolerance or activate signaling pathways leading to chronic inflammation. Herein we discuss the role of the microbiome and the OMVs that originate from intestinal bacteria in promoting chronic inflammation and the development of colitis-associated CRC. We also discuss the contribution of TLRs in mediating the microbiome-inflammation axis and subsequent cancer development. Understanding the role of the microbiome and its secretory factors in TLR response may lead to the development of better cancer therapeutics.

Extracellular vesicle activities regulating macrophage- and tissue-mediated injury and repair responses

Macrophages are typically identified as classically activated (M1) macrophages and alternatively activated (M2) macrophages, which respectively exhibit pro- and anti-inflammatory phenotypes, and the balance between these two subtypes plays a critical role in the regulation of tissue inflammation, injury, and repair processes. Recent studies indicate that tissue cells and macrophages interact via the release of small extracellular vesicles (EVs) in processes where EVs released by stressed tissue cells can promote the activation and polarization of adjacent macrophages which can in turn release EVs and factors that can promote cell stress and tissue inflammation and injury, and vice versa. This review discusses the roles of such EVs in regulating such interactions to influence tissue inflammation and injury in a number of acute and chronic inflammatory disease conditions, and the potential applications, advantage and concerns for using EV-based therapeutic approaches to treat such conditions, including their potential role of drug carriers for the treatment of infectious diseases.

Cell-Selective Altered Cargo Properties of Extracellular Vesicles Following In Vitro Exposures to Intermittent Hypoxia

Intermittent hypoxia (IH), a hallmark of obstructive sleep apnea (OSA), is associated with cardiovascular and metabolic dysfunction. However, the mechanisms underlying these morbidities remain poorly delineated. Extracellular vesicles (EVs) mediate intercellular communications, play pivotal roles in a multitude of physiological and pathological processes, and could mediate IH-induced cellular effects. Here, the effects of IH on human primary cells and the release of EVs were examined. Microvascular endothelial cells (HMVEC-d), THP1 monocytes, THP1 macrophages M0, THP1 macrophages M1, THP1 macrophages M2, pre-adipocytes, and differentiated adipocytes (HAd) were exposed to either room air (RA) or IH for 24 h. Secreted EVs were isolated and characterized using transmission electron microscopy, nanoparticle tracking analysis, and Western blotting. The effects of each of the cell-derived EVs on endothelial cell (EC) monolayer barrier integrity, on naïve THP1 macrophage polarity, and on adipocyte insulin sensitivity were also evaluated. IH did not alter EVs cell quantal release, but IH-EVs derived from HMVEC-d (p < 0.01), THP1 M0 (p < 0.01) and HAd (p < 0.05) significantly disrupted HMVEC-d monolayer integrity, particularly after H₂O₂ pre-conditioning. IH-EVs from HMVEC-d and THP1 M0 elicited M2-polarity changes did not alter insulin sensitivity responses. IH induces cell-selective changes in EVs cargo, which primarily seem to target the emergence of endothelial dysfunction. Thus, changes in EVs cargo from selected cell sources in vivo may play causal roles in some of the adverse outcomes associated with OSA.

Adipose Extracellular Vesicles: Messengers From and to Macrophages in Regulating Immunometabolic Homeostasis or Disorders

Adipose tissue is comprised of heterogenous cell populations that regulate both energy metabolism and immune reactions. Macrophages play critical roles in regulating immunometabolic homeostasis or disorders through cooperation with adipocytes, adipose tissue-derived stem cells (ADSCs) or other cells in adipose tissue. Extracellular vesicles (EVs) are recently recognized as efficient messengers for intercellular communication. Emerging evidences have demonstrated that adipose EVs are actively involved in the mutual interactions of macrophages, adipocytes and ADSCs, which produce considerable influences on immunometabolism under healthy or obese conditions. Here, we will elaborate the production and the characteristics of adipose EVs that are related to macrophages under different metabolic demands or stresses, whilst discuss the roles of these EVs in regulating local or systemic immunometabolic homeostasis or disorders in the context of adipocyte-macrophage dialogue and ADSC-macrophage interaction. Particularly, we provide a profile of dynamic adipose microenvironments based on macrophages. Adipose EVs act as the messengers between ADSCs and macrophages to maintain the balance of metabolism and immunity, while drive a vicious cycle between hypertrophic adipocytes and inflammatory macrophages to cause immunometabolic imbalance. This review may provide valuable information about the physio- or pathological roles of adipose EVs and the application of adipose EVs in the diagnosis and treatment of metabolic diseases.

Beyond the Extracellular Vesicles: Technical Hurdles, Achieved Goals and Current Challenges When Working on Adipose Cells

Adipose tissue and its crosstalk with other organs plays an essential role in the metabolic homeostasis of the entire body. Alteration of this communication (i.e., due to obesity) is related to the development of several comorbidities including type 2 diabetes, cardiovascular diseases, or cancer. Within the adipose depot, adipocytes are the main cell type and thus the main source of secreted molecules, which exert modulating effects not only at a local but also at a systemic level. Extracellular vesicles (EVs) have recently emerged as important mediators in cell–cell communication and account for part of the cellular secretome. In recent years, there has been a growing body of research on adipocyte-derived extracellular vesicles (Ad-EVs). However, there is still a lack of standardized methodological approaches, especially regarding primary adipocytes. In this review, we will provide an outline of crucial aspects when working on adipose-derived material, with a special focus on primary adipocytes. In parallel, we will point out current methodological challenges in the EV field and how they impact the transcriptomic, proteomic and functional evaluations of Ad-EVs.

Anti-Inflammatory Effects of Plasma Circulating Exosomes Obtained from Normal-Weight and Obese Subjects on Hepatocytes

INTRODUCTION

Obesity is a disorder with low-grade chronic inflammation that plays a key role in hepatic inflammation and steatosis. Moreover, there are studies to support the role of exosomes in cellular communications, the regulation of metabolic homeostasis and immunomodulatory activity. Accordingly, we aimed to evaluate the influence of plasma circulating exosomes derived from females with normal-weight and obesity on the secretion of inflammatory cytokines in human liver cells.

METHODS

Plasma circulating exosomes were isolated from four normal (N-Exo) and four obese (OExo) women. The exosomes were characterized and approved for CD63 expression (common exosomal protein marker) and morphology/size using the western blot and TEM methods, respectively. The exosomes were used for the stimulation of HepG2 cells in vitro. After 24 h of incubation, the protein levels of TNF-α, IL-6, and IL-1β were measured in the culture supernatant of HepG2 cells using the ELISA kit.

RESULTS

The protein levels of IL-6 and TNF-α in the cells treated with O-Exo and N-Exo reduced significantly in comparison with the control group (P=0.039 and P<0.001 respectively), while significant differences were not found between normal and obese groups (P=0.808, and P=0.978 respectively). However, no significant differences were found among the three groups in terms of IL-1β levels (P=0.069). Based on the correlation analysis, the protein levels of IL-6 were positively correlated with TNF-α (r 0.978, P<0.001).

CONCLUSION

These findings suggest that plasma circulating exosomes have probably antiinflammatory properties independent of body mass index and may decrease the secretion of inflammatory cytokines in the liver. However, further in vitro and in vivo investigations are needed to address the anti-inflammatory function of N-Exo and O-Exo in human liver cells and/or other cells.

Adipocyte-derived extracellular vesicles regulate survival and function of pancreatic β cells

Extracellular vesicles (EVs) are implicated in the crosstalk between adipocytes and other metabolic organs, and an altered biological cargo has been observed in EVs from human obese adipose tissue (AT). Yet, the role of adipocyte-derived EVs in pancreatic β cells remains to be determined. Here, we explored the effects of EVs released from adipocytes isolated from both rodents and humans and human AT explants on survival and function of pancreatic β cells and human pancreatic islets. EVs from healthy 3T3-L1 adipocytes increased survival and proliferation and promoted insulin secretion in INS-1E β cells and human pancreatic islets, both those untreated or exposed to cytokines or glucolipotoxicity, whereas EVs from inflamed adipocytes caused β cell death and dysfunction. Human lean adipocyte-derived EVs produced similar beneficial effects, whereas EVs from obese AT explants were harmful for human EndoC-βH3 β cells. We observed differential expression of miRNAs in EVs from healthy and inflamed adipocytes, as well as alteration in signaling pathways and expression of β cell genes, adipokines, and cytokines in recipient β cells. These in vitro results suggest that, depending on the physiopathological state of AT, adipocyte-derived EVs may influence β cell fate and function.

The Potential Role of Exosomes in Child and Adolescent Obesity

Child and adolescent obesity constitute one of the greatest contemporary public health menaces. The enduring disproportion between calorie intake and energy consumption, determined by a complex interaction of genetic, epigenetic, and environmental factors, finally leads to the development of overweight and obesity. Child and adolescent overweight/obesity promotes smoldering systemic inflammation (“para-inflammation”) and increases the likelihood of later metabolic and cardiovascular complications, including metabolic syndrome and its components, which progressively deteriorate during adulthood. Exosomes are endosome-derived extracellular vesicles that are secreted by a variety of cells, are naturally taken-up by target cells, and may be involved in many physiological and pathological processes. Over the last decade, intensive research has been conducted regarding the special role of exosomes and the non-coding (nc) RNAs they contain (primarily micro (mi) RNAs, long (l) non-coding RNAs, messenger (m) RNAs and other molecules) in inter-cellular communications. Through their action as communication mediators, exosomes may contribute to the pathogenesis of obesity and associated disorders. There is increasing evidence that exosomal miRNAs and lncRNAs are involved in pivotal processes of adipocyte biology and that, possibly, play important roles in gene regulation linked to human obesity. This review aims to improve our understanding of the roles of exosomes and their cargo in the development of obesity and related metabolic and inflammatory disorders. We examined their potential roles in adipose tissue physiology and reviewed the scarce data regarding the altered patterns of circulating miRNAs and lncRNAs observed in obese children and adolescents, compared them to the equivalent, more abundant existing findings of adult studies, and speculated on their proposed mechanisms of action. Exosomal miRNAs and lncRNAs could be applied as cardiometabolic risk biomarkers, useful in the early diagnosis and prevention of obesity. Furthermore, the targeting of crucial circulating exosomal cargo to tissues involved in the pathogenesis and maintenance of obesity could provide a novel therapeutic approach to this devastating and management-resistant pandemic.

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.

Adipose Extracellular Vesicles in Intercellular and Inter-Organ Crosstalk in Metabolic Health and Diseases

Adipose tissue (AT) is a highly heterogeneous and dynamic organ that plays important roles in regulating energy metabolism and insulin sensitivity. In addition to its classical roles in nutrient sensing and energy storage/dissipation, AT secretes a large number of bioactive molecules (termed adipokines) participating in immune responses and metabolic regulation through their paracrine and/or endocrine actions. Adipose-derived extracellular vesicles (ADEVs), including exosomes, microvesicles (MVs), and apoptotic bodies, have recently emerged as a novel class of signal messengers, mediating intercellular communications and inter-organ crosstalk. In AT, ADEVs derived from adipocytes, immune cells, mesenchymal stem cells, endothelial cells are actively involved in modulation of immune microenvironment, adipogenesis, browing of white adipose tissue, adipokine release and tissue remodeling. Furthermore, ADEVs exert their metabolic actions in distal organs (such as liver, skeletal muscle, pancreas and brain) by sending genetic information (mainly in the form of microRNAs) to their target cells for regulation of gene expression. Here, we provide an updated summary on the nature and composition of ADEVs, and their pathophysiological functions in regulating immune responses, whole-body insulin sensitivity and metabolism. Furthermore, we highlight the latest clinical evidence supporting aberrant production and/or function of ADEVs as a contributor to obesity-related chronic inflammation and metabolic complications and discuss the opportunities and challenges in developing novel therapies by targeting ADEVs.

Dark-Side of Exosomes

Exosomes are nanoscale extracellular vesicles that can transport cargos of proteins, lipids, DNA, various RNA species and microRNAs (miRNAs). Exosomes can enter cells and deliver their contents to recipient cell. Owing to their cargo exosomes can transfer different molecules to the target cells and change the phenotype of these cells. The fate of the contents of an exosome depends on its target destination. Various mechanisms for exosome uptake by target cells have been proposed, but the mechanisms responsible for exosomes internalization into cells are still debated. Exosomes exposed cells produce labeled protein kinases, which are expressed by other cells. This means that these kinases are internalized by exosomes, and transported into the cytoplasm of recipient cells. Many studies have confirmed that exosomes are not only secreted by living cells, but also internalized or accumulated by the other cells. The "next cell hypothesis" supports the notion that exosomes constitute communication vehicles between neighboring cells. By this mechanism, exosomes participate in the development of diabetes and its associated complications, critically contribute to the spreading of neuronal damage in Alzheimer's disease, and non-proteolysed form of Fas ligand (mFasL)-bearing exosomes trigger the apoptosis of T lymphocytes. Furthermore, exosomes derived from human B lymphocytes induce antigen-specific major histocompatibility complex (MHC) class II-restricted T cell responses. Interestingly, exosomes secreted by cancer cells have been demonstrated to express tumor antigens, as well as immune suppressive molecules. This process is defined as "exosome-immune suppression" concept. The interplay via the exchange of exosomes between cancer cells and between cancer cells and the tumor stroma promote the transfer of oncogenes and onco-miRNAs from one cell to other. Circulating exosomes that are released from hypertrophic adipocytes are effective in obesity-related complications. On the other hand, the "inflammasome-induced" exosomes can activate inflammatory responses in recipient cells. In this chapter protein kinases-related checkpoints are emphasized considering the regulation of exosome biogenesis, secretory traffic, and their impacts on cell death, tumor growth, immune system, and obesity.

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.

Exosomes from adipose-derived stem cells and application to skin wound healing

Skin wound healing is an intractable problem that represents an urgent clinical need. To solve this problem, a large number of studies have focused on the use of exosomes (EXOs) derived from adipose‐derived stem cells (ADSCs). This review describes the mechanisms whereby ADSCs‐EXOs regulate wound healing and their clinical application. In the wound, ADSCs‐EXOs modulate immune responses and inflammation. They also promote angiogenesis, accelerate proliferation and re‐epithelization of skin cells, and regulate collagen remodelling which inhibits scar hyperplasia. Compared with ADSCs therapeutics, ADSCs‐EXOs have highly stability and are easily stored. Additionally, they are not rejected by the immune system and have a homing effect and their dosage can be easily controlled. ADSCs‐EXOs can improve fat grafting and promote wound healing in patients with diabetes mellitus. They can also act as a carrier and combined scaffold for treatment, leading to scarless cutaneous repair. Overall, ADSCs‐EXOs have the potential to be used in the clinic to promote wound healing.

Extracellular Vesicles in Comorbidities Associated with Ischaemic Heart Disease: Focus on Sex, an Overlooked Factor

Extracellular vesicles (EV) are emerging early markers of myocardial damage and key mediators of cardioprotection. Therefore, EV are becoming fascinating tools to prevent cardiovascular disease and feasible weapons to limit ischaemia/reperfusion injury. It is well known that metabolic syndrome negatively affects vascular and endothelial function, thus creating predisposition to ischemic diseases. Additionally, sex is known to significantly impact myocardial injury and cardioprotection. Therefore, actions able to reduce risk factors related to comorbidities in ischaemic diseases are required to prevent maladaptive ventricular remodelling, preserve cardiac function, and prevent the onset of heart failure. This implies that early diagnosis and personalised medicine, also related to sex differences, are mandatory for primary or secondary prevention. Here, we report the contribution of EV as biomarkers and/or therapeutic tools in comorbidities predisposing to cardiac ischaemic disease. Whenever possible, attention is dedicated to data linking EV to sex differences.

Extracellular Vesicles in Metabolism and Metabolic Diseases

As living organisms constantly need energy to maintain and perform cellular functions, metabolism plays a vital role in producing the required energy to execute these processes. Hence, various metabolic pathways are highly regulated and disruption in critical pathways can result in the onset of multiple disorders such as hypertension, diabetes, obesity, and dyslipidaemia. Extracellular vesicles (EVs) are membrane-bound nanosized vesicles that are known to be secreted by various cell types into their respective extracellular environment. EVs have been implicated in cell-to-cell communication via mediating cellular signaling and can functionally impact recipient cells with the transport of bioactive proteins, nucleic acids, lipids and cellular metabolites. Recently, several studies have highlighted the role of EVs in metabolism. Alterations in the plasma derived EV concentration and their cargo in patients with metabolic disorders have been reported by multiple studies, further proposing EVs as a potential source of disease biomarkers. The following chapter will discuss the functional significance of EVs in metabolic diseases and the processes by which EVs act as cellular messengers to reprogram the metabolic machinery in recipient cells.

The Role of Mesenchymal Stromal Cells-Derived Small Extracellular Vesicles in Diabetes and Its Chronic Complications

Mesenchymal stromal cells (MSCs) are applied in regenerative medicine of several tissues and organs nowadays by virtue of their self-renewal capabilities, multiple differentiation capacity, potent immunomodulatory properties, and their ability to be favourably cultured and manipulated. With the continuous development of "cell-free therapy" research, MSC-derived small extracellular vesicles (MSC-sEVs) have increasingly become a research hotspot in the treatment of various diseases. Small extracellular vesicles (SEVs) are membrane vesicles with diameters of 30 to 150 nm that mediate signal transduction between adjacent or distal cells or organs by delivering non-coding RNA, protein, and DNA. The contents and effects of sEVs vary depending on the properties of the originating cell. In recent years, MSC-sEVs have been found to play an important role in the occurrence and development of diabetes mellitus as a new way of communication between cells. Diabetes mellitus is a common metabolic disease in clinic. Its complications of the heart, brain, kidney, eyes, and peripheral nerves are a serious threat to human health and has been a hot issue for clinicians. MSC-sEVs could be applied to repair or prevent damage from the complications of diabetes mellitus through anti-inflammatory effects, reduction of endoplasmic reticulum-related protein stress, polarization of M2 macrophages, and increasing autophagy. Therefore, we highly recommend that MSC-sEVs-based therapies to treat diabetes mellitus and its chronic complication be further explored. The analysis of the role and molecular mechanisms of MSC-sEVs in diabetes and its related complications will provide new idea and insights for the prevention and treatment of diabetes.

Extracellular Vesicles from Adipose Tissue Stem Cells in Diabetes and Associated Cardiovascular Disease; Pathobiological Impact and Therapeutic Potential

Adipose tissue-derived stem cells (ADSCs) are pluripotent mesenchymal stem cells found in relatively high percentages in the adipose tissue and able to self-renew and differentiate into many different types of cells. “Extracellular vesicles (EVs), small membrane vesicular structures released during cell activation, senescence, or apoptosis, act as mediators for long distance communication between cells, transferring their specific bioactive molecules into host target cells”. There is a general consensus on how to define and isolate ADSCs, however, multiple separation and characterization protocols are being used in the present which complicate the results’ integration in a single theory on ADSCs’ and their derived factors’ way of action. Metabolic syndrome and type 2 diabetes mellitus (T2DM) are mainly caused by abnormal adipose tissue size, distribution and metabolism and so ADSCs and their secretory factors such as EVs are currently investigated as therapeutics in these diseases. Moreover, due to their relatively easy isolation and propagation in culture and their differentiation ability, ADSCs are being employed in preclinical studies of implantable devices or prosthetics. This review aims to provide a comprehensive summary of the current knowledge on EVs secreted from ADSCs both as diagnostic biomarkers and therapeutics in diabetes and associated cardiovascular disease, the molecular mechanisms involved, as well as on the use of ADSC differentiation potential in cardiovascular tissue repair and prostheses.

Deciphering Adipose Tissue Extracellular Vesicles Protein Cargo and Its Role in Obesity

The extracellular vesicles (EVs) have emerged as key players in metabolic disorders rising as an alternative way of paracrine/endocrine communication. In particular, in relation to adipose tissue (AT) secreted EVs, the current knowledge about its composition and function is still very limited. Nevertheless, those vesicles have been lately suggested as key players in AT communication at local level, and also with other metabolic peripheral and central organs participating in physiological homoeostasis, and also contributing to the metabolic deregulation related to obesity, diabetes, and associated comorbidities. The aim of this review is to summarize the most relevant data around the EVs secreted by adipose tissue, and especially in the context of obesity, focusing in its protein cargo. The description of the most frequent proteins identified in EVs shed by AT and its components, including their changes under pathological status, will give the reader a whole picture about the membrane/antigens, and intracellular proteins known so far, in an attempt to elucidate functional roles, and also suggesting biomarkers and new paths of therapeutic action.

Extracellular vesicles in diabetes mellitus induce alterations in endothelial cell morphology and migration

Background

Inflammation-related atherosclerotic peripheral vascular disease is a major end organ complication of diabetes mellitus that results in devastating morbidity and mortality. Extracellular vesicles (EVs) are nano-sized particles that contain molecular cargo and circulate in the blood. Here, we examined EV protein cargo from diabetic individuals and whether these EVs cause functional changes in endothelial cells.

Methods

We quantified inflammatory protein levels in plasma-derived EVs from a longitudinal cohort of euglycemic and diabetic individuals and used in vitro endothelial cell biological assays to assess the functional effects of these EVs with samples from a cross-sectional cohort.

Results

We found several significant associations between EV inflammatory protein levels and diabetes status. The angiogenic factor, vascular endothelial growth factor A (VEGF-A), was associated with diabetes status in our longitudinal cohort. Those with diabetes mellitus had higher EV VEGF-A levels compared to euglycemic individuals. Additionally, EV levels of VEGF-A were significantly associated with homeostatic model assessment of insulin resistance (HOMA-IR) and β-cell function (HOMA-B). To test whether EVs with different inflammatory cargo can demonstrate different effects on endothelial cells, we performed cell migration and immunofluorescence assays. We observed that EVs from diabetic individuals increased cell lamellipodia formation and migration when compared to EVs from euglycemic individuals.

Conclusions

Higher levels of inflammatory proteins were found in EVs from diabetic individuals. Our data implicate EVs as playing important roles in peripheral vascular disease that occur in individuals with diabetes mellitus and suggest that EVs may serve as an informative diagnostic tool for the disease.

Extracellular vesicles as signaling mediators in type 2 diabetes mellitus

Diabetes mellitus type 2, a chronic metabolic disease, has globally increased in incidence and prevalence throughout the lifespan due to the rise in obesity and sedentary lifestyle. The end-organ cardiovascular and cerebrovascular effects of diabetes mellitus result in significant morbidity and mortality that increases with age. Thus, it is crucial to fully understand how molecular mechanisms are influenced by diabetes mellitus and may influence the development of end-organ complications. Circulating factors are known to play important physiological and pathological roles in diabetes. Recent data have implicated extracellular vesicles (EVs) as being circulating mediators in type 2 diabetes. These small lipid-bound vesicles are released by cells into the circulation and can carry functional cargo, including lipids, proteins, and nucleic acids, to neighboring cells or between tissues. In this review, we will summarize the current evidence for EVs as promising diagnostic and prognostic factors in diabetes, the mechanisms that drive EV alterations with diabetes, and the role EVs play in the pathology associated with diabetes.

Vesicles Shed by Pathological Murine Adipocytes Spread Pathology: Characterization and Functional Role of Insulin Resistant/Hypertrophied Adiposomes

Extracellular vesicles (EVs) have recently emerged as a relevant way of cell to cell communication, and its analysis has become an indirect approach to assess the cell/tissue of origin status. However, the knowledge about their nature and role on metabolic diseases is still very scarce. We have established an insulin resistant (IR) and two lipid (palmitic/oleic) hypertrophied adipocyte cell models to isolate EVs to perform a protein cargo qualitative and quantitative Sequential Window Acquisition of All Theoretical Mass Spectra (SWATH) analysis by mass spectrometry. Our results show a high proportion of obesity and IR-related proteins in pathological EVs; thus, we propose a panel of potential obese adipose tissue EV-biomarkers. Among those, lipid hypertrophied vesicles are characterized by ceruloplasmin, mimecan, and perilipin 1 adipokines, and those from the IR by the striking presence of the adiposity and IR related transforming growth factor-beta-induced protein ig-h3 (TFGBI). Interestingly, functional assays show that IR and hypertrophied adipocytes induce differentiation/hypertrophy and IR in healthy adipocytes through secreted EVs. Finally, we demonstrate that lipid atrophied adipocytes shed EVs promote macrophage inflammation by stimulating IL-6 and TNFα expression. Thus, we conclude that pathological adipocytes release vesicles containing representative protein cargo of the cell of origin that are able to induce metabolic alterations on healthy cells probably exacerbating the disease once established.

Small Extracellular Microvesicles Mediated Pathological Communications Between Dysfunctional Adipocytes and Cardiomyocytes as a Novel Mechanism Exacerbating Ischemia/Reperfusion Injury in Diabetic Mice

BACKGROUND

Diabetes mellitus exacerbates myocardial ischemia/reperfusion (MI/R) injury by incompletely understood mechanisms. Adipocyte dysfunction contributes to remote organ injury. However, the molecular mechanisms linking dysfunctional adipocytes to increased MI/R injury remain unidentified. The current study attempted to clarify whether and how small extracellular vesicles (sEV) may mediate pathological communication between diabetic adipocytes and cardiomyocytes, exacerbating MI/R injury.

METHODS

Adult male mice were fed a normal or a high-fat diet for 12 weeks. sEV (from diabetic serum, diabetic adipocytes, or high glucose/high lipid-challenged nondiabetic adipocytes) were injected intramyocardially distal of coronary ligation. Animals were subjected to MI/R 48 hours after injection.

RESULTS

Intramyocardial injection of diabetic serum sEV in the nondiabetic heart significantly exacerbated MI/R injury, as evidenced by poorer cardiac function recovery, larger infarct size, and greater cardiomyocyte apoptosis. Similarly, intramyocardial or systemic administration of diabetic adipocyte sEV or high glucose/high lipid-challenged nondiabetic adipocyte sEV significantly exacerbated MI/R injury. Diabetic epididymal fat transplantation significantly increased MI/R injury in nondiabetic mice, whereas administration of a sEV biogenesis inhibitor significantly mitigated MI/R injury in diabetic mice. A mechanistic investigation identified that miR-130b-3p is a common molecule significantly increased in diabetic serum sEV, diabetic adipocyte sEV, and high glucose/high lipid-challenged nondiabetic adipocyte sEV. Mature (but not primary) miR-130b-3p was significantly increased in the diabetic and nondiabetic heart subjected to diabetic sEV injection. Whereas intramyocardial injection of a miR-130b-3p mimic significantly exacerbated MI/R injury in nondiabetic mice, miR-130b-3p inhibitors significantly attenuated MI/R injury in diabetic mice. Molecular studies identified AMPKα1/α2, Birc6, and Ucp3 as direct downstream targets of miR-130b-3p. Overexpression of these molecules (particularly AMPKα2) reversed miR-130b-3p induced proapoptotic/cardiac harmful effect. Finally, miR-130b-3p levels were significantly increased in plasma sEV from patients with type 2 diabetes mellitus. Incubation of cardiomyocytes with diabetic patient sEV significantly exacerbated ischemic injury, an effect blocked by miR-130b-3p inhibitor.

CONCLUSIONS

We demonstrate for the first time that miR-130b-3p enrichment in dysfunctional adipocyte-derived sEV, and its suppression of multiple antiapoptotic/cardioprotective molecules in cardiomyocytes, is a novel mechanism exacerbating MI/R injury in the diabetic heart. Targeting miR-130b-3p mediated pathological communication between dysfunctional adipocytes and cardiomyocytes may be a novel strategy attenuating diabetic exacerbation of MI/R injury.

Adipose Tumor Microenvironment

The term "adipose tissue" represents a multicellular and multifunctional organ involved in lipid storage, in hormone and temperature regulation, and in the protection of bones and vital organs from impact-based damage. Emerging evidence now suggests a more malignant role of adipose tissue in promoting cancer onset and progression via the release of secreted factors such as interleukin-6 (IL6) and extracellular vesicles (EVs). These adipose-source factors subsequently affect various aspects of tumorigenesis and/or cancer progression by either directly enhancing the tumor cell oncogenic phenotype or indirectly by the stimulating adjacent normal cells to adopt a more pro-cancer phenotype. Due to the recent growing interest in the role of IL6 and EVs released by adipose tissue in cancer promotion and progression, we are focusing on the protumorigenic impact of fat tissue via IL6 and EV secretion.

The Interplay Between Tissue Niche and Macrophage Cellular Metabolism in Obesity

Obesity is associated with the development of metabolic diseases such as type 2 diabetes and non-alcoholic fatty liver disease. The presence of chronic, low-grade inflammation appears to be an important mechanistic link between excess nutrients and clinical disease. The onset of these metabolic disorders coincides with changes in the number and phenotype of macrophages in peripheral organs, particularly in the liver and adipose tissue. Macrophage accumulation in these tissues has been implicated in tissue inflammation and fibrosis, contributing to metabolic disease progression. Recently, the concept has emerged that changes in macrophage metabolism affects their functional phenotype, possibly triggered by distinct environmental metabolic cues. This may be of particular importance in the setting of obesity, where both liver and adipose tissue are faced with a high metabolic burden. In the first part of this review we will discuss current knowledge regarding macrophage dynamics in both adipose tissue and liver in obesity. Then in the second part, we will highlight data linking macrophage metabolism to functional phenotype with an emphasis on macrophage activation in metabolic disease. The importance of understanding how tissue niche influences macrophage function in obesity will be highlighted. In addition, we will identify important knowledge gaps and outstanding questions that are relevant for future research in this area and will facilitate the identification of novel targets for therapeutic intervention in associated metabolic diseases.

Microvesicles and exosomes in metabolic diseases and inflammation

Metabolic diseases are based on a dysregulated crosstalk between various cells such as adipocytes, hepatocytes and immune cells. Generally, hormones and metabolites mediate this crosstalk that becomes alterated in metabolic syndrome including obesity and diabetes. Recently, Extracellular Vesicles (EVs) are emerging as a novel way of cell-to-cell communication and represent an attractive strategy to transfer fundamental informations between the cells through the transport of proteins and nucleic acids. EVs, released in the extracellular space, circulate via the various body fluids and modulate the cellular responses following their interaction with the near and far target cells. Clinical and experimental data support their role as biomarkers and bioeffectors in several diseases includimg also the metabolic syndrome. Despite numerous studies on the role of macrophages in the development of metabolic diseases, to date, there are little informations about the influence of metabolic stress on the EVs produced by macrophages and about the role of the released vesicles in the organism. Here, we review current understanding about the role of EVs in metabolic diseases, mainly in inflammation status burst. This knowledge may play a relevant role in health monitoring, medical diagnosis and personalized medicine.

Mechanisms of Endothelial Dysfunction in Pre-eclampsia and Gestational Diabetes Mellitus: Windows Into Future Cardiometabolic Health?

Placental insufficiency and adipose tissue dysregulation are postulated to play key roles in the pathophysiology of both pre-eclampsia (PE) and gestational diabetes mellitus (GDM). A dysfunctional release of deleterious signaling motifs can offset an increase in circulating oxidative stressors, pro-inflammatory factors and various cytokines. It has been previously postulated that endothelial dysfunction, instigated by signaling from endocrine organs such as the placenta and adipose tissue, may be a key mediator of the vasculopathy that is evident in both adverse obstetric complications. These signaling pathways also have significant effects on long term maternal cardiometabolic health outcomes, specifically cardiovascular disease, hypertension, and type II diabetes. Recent studies have noted that both PE and GDM are strongly associated with lower maternal flow-mediated dilation, however the exact pathways which link endothelial dysfunction to clinical outcomes in these complications remains in question. The current diagnostic regimen for both PE and GDM lacks specificity and consistency in relation to clinical guidelines. Furthermore, current therapeutic options rely largely on clinical symptom control such as antihypertensives and insulin therapy, rather than that of early intervention or prophylaxis. A better understanding of the pathogenic origin of these obstetric complications will allow for more targeted therapeutic interventions. In this review we will explore the complex signaling relationship between the placenta and adipose tissue in PE and GDM and investigate how these intricate pathways affect maternal endothelial function and, hence, play a role in acute pathophysiology and the development of future chronic maternal health outcomes.

Effect of circulating exosomes derived from normal-weight and obese women on gluconeogenesis, glycogenesis, lipogenesis and secretion of FGF21 and fetuin A in HepG2 cells

BACKGROUND

It is generally accepted that obesity can lead to metabolic disorders such as NAFLD and insulin resistance. However, the underlying mechanism has been poorly understood. Moreover, there is evidence to support the possible role of exosomes in the metabolic homeostasis regulation. Accordingly, we aimed to determine the effect of plasma circulating exosomes derived from obese and normal-weight women on insulin signaling and the secretion of hepatokines in human liver cells.

METHODS

Plasma exosomes isolated from four obese (O-Exo) women and four normal-weight (N-Exo) female candidates were characterized for size, zeta potential, and CD63 protein expression and were used for stimulation of HepG2 cells. Then, cell viability, as well as levels of glycogen and triglyceride (TG), were evaluated. Levels of fetuin-A and FGF21 were measured using the ELISA kit. Expression of glucose 6-phosphatase (G6pase) and phosphoenolpyruvate carboxykinase (PEPCK) genes were determined using qRT-PCR. Western blot analysis was carried out to evaluating the phosphorylation of GSK3β.

RESULTS

The TG levels increased significantly in the cells treated with O-Exo than the control (vehicle) group (P = 0.005) and normal-weight group (P = 0.018). Levels of p-GSK3β and glycogen were significantly reduced by O-Exo in comparison with control (P = 0.002, P = 0.018, respectively). The mRNA expression of G6pase and PEPCK enzymes increased in the cells treated with O-Exo in comparison with the vehicle group (P = 0.017, P = 0.010, respectively). The levels of FGF21 in the supernatant of cells treated with O-Exo and N-Exo were significantly lower than the control group (P = 0.007).

CONCLUSION

It appears that obesity-related circulating exosomes can impair insulin signaling pathways and associated components, increase intracellular TG content, and decrease FGF21 secretion in the hepatocytes.

Marrow Fat-Secreted Factors as Biomarkers for Osteoporosis

PURPOSE OF REVIEW

The age-related accumulation of bone marrow adipose tissue (BMAT) negatively impacts bone metabolism and hematopoiesis. This review provides an overview about BMAT-secreted factors as biomarkers for BMAT accumulation and osteoporosis risk.

RECENT FINDINGS

The adipokines leptin and adiponectin are regulators of BMAT. It remains to be clarified if locally produced adipokines substantially contribute to their peripheral serum levels and if they influence bone metabolism beyond that of extraosseous adipokine production. Existing data also suggests that BMAT disturbs bone metabolism primarily through palmitate-mediated toxic effects on osteoblasts and osteocytes, including dysregulated autophagy and apoptosis. BMAT-secreted factors are important modulators of bone metabolism. However, the majority of our understanding about MAT-secreted factors and their paracrine and endocrine effects is derived from in vitro studies and animal experiments. Therefore, more research is needed before BMAT-secreted biomarkers can be applied in medical practice.

Contributions of innate type 2 inflammation to adipose function

A critical contributor to the health consequences of the obesity epidemic is dysregulated adipose tissue (AT) homeostasis. While white, brown, and beige AT function is altered in obesity-related disease, white AT is marked by progressive inflammation and adipocyte dysfunction and has been the focus of extensive "immunometabolism" research in the past decade. The exact triggering events initiating and sustaining AT inflammation are still under study, but it has been shown that reducing inflammation improves insulin action in AT. Scientific efforts seeking interventions to mitigate obesity-associated AT inflammation continue, and many groups are now determining how lean healthy AT homeostasis is maintained in order to leverage these mechanisms as therapeutic targets. Such studies have revealed that an elaborate network of immune cells, cytokines, and other cellular mediators coordinate AT function. Recent studies elucidated the involvement of the innate immune system in AT homeostasis (e.g., beiging and insulin sensitivity), including M2-like macrophages, eosinophils, innate lymphoid type 2 cells, and several others. In this review, we summarize the existing literature on innate type 2 inflammation in AT; additionally, we draw attention to areas of debate where seemingly conflicting data promises to yield more surprising and elegant biology as studies continue to dissect AT physiology.