Immunomodulatory role of microRNAs transferred by extracellular vesicles

Regulation of immune responses to infection through interaction between stem cell-derived exosomes and toll-like receptors mediated by microRNA cargoes

Infectious diseases are among the factors that account for a significant proportion of disease-related deaths worldwide. The primary treatment approach to combat microbial infections is the use of antibiotics. However, the widespread use of these drugs over the past two decades has led to the emergence of resistant microbial species, making the control of microbial infections a serious challenge. One of the most important solutions in the field of combating infectious diseases is the regulation of the host's defense system. Toll-like receptors (TLRs) play a crucial role in the first primary defense against pathogens by identifying harmful endogenous molecules released from dying cells and damaged tissues as well as invading microbial agents. Therefore, they play an important role in communicating and regulating innate and adaptive immunity. Of course, excessive activation of TLRs can lead to disruption of immune homeostasis and increase the risk of inflammatory reactions. Targeting TLR signaling pathways has emerged as a new therapeutic approach for infectious diseases based on host-directed therapy (HDT). In recent years, stem cell-derived exosomes have received significant attention as factors regulating the immune system. The regulation effects of exosomes on the immune system are based on the HDT strategy, which is due to their cargoes. In general, the mechanism of action of stem cell-derived exosomes in HDT is by regulating and modulating immunity, promoting tissue regeneration, and reducing host toxicity. One of their most important cargoes is microRNAs, which have been shown to play a significant role in regulating immunity through TLRs. This review investigates the therapeutic properties of stem cell-derived exosomes in combating infections through the interaction between exosomal microRNAs and Toll-like receptors.

Circulating microRNA-155-3p levels predicts response to first line immunotherapy in patients with metastatic renal cell carcinoma

Predictive biomarkers of response to immune checkpoint-based therapies (ICI) remain a critically unmet need in the management of advanced renal cell carcinoma (RCC). The complex interplay of the tumour microenvironment (TME) and the circulating immune response has proven to be challenging to decipher. MicroRNAs have gained increasing attention for their role in post-transcriptional gene expression regulation, particularly because they can have immunomodulatory properties. We evaluated the presence of immune-specific extracellular vesicle (EV) microRNAs in the plasma of patients with metastatic RCC (mRCC) prior to initiation of ICI. We found significantly lower levels of microRNA155-3p (miR155) in responders to ICI, when compared to non-responders. This microRNA has unique immunomodulatory properties, thus providing potential biological rationale for our findings. Our results support further work in exploring microRNAs as potential biomarkers of response to immunotherapy.

Extracellular vesicles-coupled miRNAs from oviduct and uterus modulate signaling pathways related to lipid metabolism and bovine early embryo development

BACKGROUND

Extracellular vesicles (EVs) present in oviductal (OF) and uterine fluid (UF) have been shown to enhance bovine embryo quality during in vitro culture by reducing lipid contents and modulating lipid metabolism-related genes (LMGs), while also influencing cell proliferation, suggesting their involvement on the regulation of different biological pathways. The regulation of signaling pathways related to cell differentiation, proliferation, and metabolism is crucial for early embryo development and can determine the success or failure of the pregnancy. Bioactive molecules within EVs in maternal reproductive fluids, such as microRNAs (miRNAs), may contribute to this regulatory process as they modulate gene expression through post-transcriptional mechanisms.

RESULTS

From the 20 differentially expressed miRNAs, 19 up-regulated in UF-EVs (bta-miR-134, bta-miR-151-3p, bta-miR-155, bta-miR-188, bta-miR-181b, bta-miR-181d, bta-miR-224, bta-miR-23b-3p, bta-miR-24-3p, bta-miR-27a-3p, bta-miR-29a, bta-miR-324, bta-miR-326, bta-miR-345-3p, bta-miR-410, bta-miR-652, bta-miR-677, bta-miR-873 and bta-miR-708) and one (bta-miR-148b) in OF-EVs. These miRNAs were predicted to modulate several pathways such as Wnt, Hippo, MAPK, and lipid metabolism and degradation. Differences in miRNAs found in OF-EVs from the early luteal phase and UF-EVs from mid-luteal phase may reflect different environments to meet the changing needs of the embryo. Additionally, miRNAs may be involved, particularly in the uterus, in the regulation of embryo lipid metabolism, immune system, and implantation. This study evaluated miRNA cargo in OF-EVs from the early luteal phase and UF-EVs from the mid-luteal phase, coinciding with embryo transit within oviduct and uterus in vivo, and its possible influence on LMGs and signaling pathways crucial for early embryo development. A total of 333 miRNAs were detected, with 11 exclusive to OF, 59 to UF, and 263 were common between both groups.

CONCLUSIONS

Our study suggests that miRNAs within OF- and UF-EVs could modulate bovine embryo development and quality, providing insights into the intricate maternal-embryonic communication that might be involved in modulating lipid metabolism, immune response, and implantation during early pregnancy.

A Group of Highly Secretory miRNAs Correlates with Lymph Node Metastasis and Poor Prognosis in Oral Squamous Cell Carcinoma

MicroRNAs (miRNAs) in oral squamous cell carcinoma (OSCC)-derived small extracellular vesicles (sEVs) play a pivotal role in modulating intercellular communications between tumor cells and other cells in the microenvironment, thereby influencing tumor progression and the efficacy of therapeutic interventions. However, a comprehensive inventory of these secretory miRNAs in sEVs and their biological and clinical implications remains elusive. This study aims to profile the miRNA content of OSCC cell line sEVs and computationally elucidate their biological and clinical relevance. We conducted miRNA sequencing to compare the miRNA profiles of OSCC cells and their corresponding sEVs. Our motif enrichment analysis identified specific sorting motifs that are implicated in either cellular retention or preferential sEV secretion. Target cell analysis suggested that the sEV miRNAs potentially interact with various immune cell types, including natural killer cells and dendritic cells. Additionally, we explored the clinical relevance of these miRNAs by correlating their expression levels with TNM stages and patient survival outcomes. Intriguingly, our findings revealed that a distinct sEV miRNA signature is associated with lymph node metastasis and poorer survival in patients in TCGA-HNSC dataset. Collectively, this research furthers our understanding of the miRNA sorting mechanisms in OSCC and underscores their clinical implications.

Mesenchymal stromal cell derived extracellular vesicles as a therapeutic tool: immune regulation, MSC priming, and applications to SLE

Systemic lupus erythematosus (SLE) is a chronic autoimmune disease characterized by a dysfunction of the immune system. Mesenchymal stromal cell (MSCs) derived extracellular vesicles (EVs) are nanometer-sized particles carrying a diverse range of bioactive molecules, such as proteins, miRNAs, and lipids. Despite the methodological disparities, recent works on MSC-EVs have highlighted their broad immunosuppressive effect, thus driving forwards the potential of MSC-EVs in the treatment of chronic diseases. Nonetheless, their mechanism of action is still unclear, and better understanding is needed for clinical application. Therefore, we describe in this review the diverse range of bioactive molecules mediating their immunomodulatory effect, the techniques and possibilities for enhancing their immune activity, and finally the potential application to SLE.

BeWo exomeres are enriched for bioactive extracellular placenta-specific C19MC miRNAs

Extracellular vesicles (EVs), including exosomes, are carriers of extracellular microRNAs (miRNAs). Exomeres, non-vesicular extracellular nanoparticles (NVEPs), are novel extracellular cargo carriers. However, little is known of the characteristics of placental trophoblast-derived exomeres. In this study, we characterized trophoblast-derived exomeres and investigated the cell-cell communication of placenta-specific miRNAs carried by those exomeres using an in vitro model system (BeWo trophoblasts and Jurkat T cells). BeWo exomeres (∼ 40 nm diameter) had pilling-like nanoparticle structures, which were distinct from cup-shaped exosomes (∼ 90-110 nm diameter). BeWo cells secreted more exomeres than exosomes. Exomeres were positive for AGO2 but negative for exosome markers (CD63, CD9, CD81, FLOT1, and TSG101). The levels of placenta-specific miRNAs in exomeres were significantly higher than in exosomes. In a cell-cell communication analysis using a placenta-specific miRNA, BeWo exomeres delivered significantly more miR-517a-3p to recipient Jurkat cells compared with exosomes. Moreover, exomere-miR-517a-3p significantly reduced the expression of PRKG1 in miR-517a-3p-inhibitor (-) Jurkat cells compared with miR-517a-3p-inhibitor (+) cells, suggesting that miR-517a-3p inhibition reversed the exomere-miR-517a-3p-mediated repression of PRKG1 expression in recipient cells. Therefore, BeWo trophoblast exomeres are enriched with bioactive extracellular placenta-specific miRNAs, which were formerly considered to be carried by exosomes. Our findings provide insight into trophoblast-derived NVEPs.

Extracellular vesicles in bacterial and fungal diseases - Pathogenesis to diagnostic biomarkers

Intercellular communication among microbes plays an important role in disease exacerbation. Recent advances have described small vesicles, termed as "extracellular vesicles" (EVs), previously disregarded as "cellular dust" to be vital in the intracellular and intercellular communication in host-microbe interactions. These signals have been known to initiate host damage and transfer of a variety of cargo including proteins, lipid particles, DNA, mRNA, and miRNAs. Microbial EVs, referred to generally as "membrane vesicles" (MVs), play a key role in disease exacerbation suggesting their importance in pathogenicity. Host EVs help coordinate antimicrobial responses and prime the immune cells for pathogen attack. Hence EVs with their central role in microbe-host communication, may serve as important diagnostic biomarkers of microbial pathogenesis. In this review, we summarize current research regarding the roles of EVs as markers of microbial pathogenesis with specific focus on their interaction with host immune defence and their potential as diagnostic biomarkers in disease conditions.

Bone marrow mesenchymal stem cells to ameliorate experimental autoimmune encephalomyelitis via modifying expression patterns of miRNAs

INTRODUCTION

Clinical and experimental studies highlighted the significant therapeutic role of Mesenchymal stem cells (MSCs) in neurodegenerative diseases. MSCs possess potent immunomodulatory properties by releasing exosomes, which generate a suitable microenvironment. microRNAs (miRNAs), as one of several effective bioactive molecules of exosomes, influence cellular communication and activities in recipient cells. Recent studies revealed that miRNAs could control the progression of multiple sclerosis (MS) via differentiation and function of T helper cells (Th).

METHODS

Here, we investigated the therapeutic effects of syngeneic-derived BM-MSC in experimental autoimmune encephalomyelitis (EAE) mouse model of MS by evaluating expression profile of miRNAs, pro- and anti-inflammatory in serum and brain tissues. Three-time scheme groups (6th day, 6th & 12th days, and 12th day, of post-EAE induction) were applied to determine the therapeutic effects of intraperitoneally received 1*106 of BM-MSCs.

RESULTS

The expression levels of mature isoforms of miR-193, miR-146a, miR-155, miR-21, and miR-326 showed that BM-MSCs treatment attenuated the EAE clinical score and reduced clinical inflammation as well as demyelination. The improved neurological functional outcome associated with enhanced expression of miR-193 and miR-146a, but decreased expression levels of miR-155, miR-21, and miR-326 were followed by suppressing effects on Th1/Th17 immune responses (reduced levels of IFN-γand IL-17 cytokine expression) and induction of Treg cells, immunoregulatory responses (increase of IL-10, TGF-β, and IL-4) in treatment groups.

CONCLUSION

Our findings suggest that BM-MSCs administration might change expression patterns of miRNAs and downstream interactions followed by immune system modulation. However, there is a need to carry out future human clinical trials and complementary experiments.

Doxorubicin–Mediated miR–433 Expression on Exosomes Promotes Bystander Senescence in Multiple Myeloma Cells in a DDR–Independent Manner

The success of senescence-based anticancer therapies relies on their anti-proliferative power and on their ability to trigger anti-tumor immune responses. Indeed, genotoxic drug-induced senescence increases the expression of NK cell-activating ligands on multiple myeloma (MM) cells, boosting NK cell recognition and effector functions. Senescent cells undergo morphological change and context-dependent functional diversification, acquiring the ability to secrete a vast pool of molecules termed the senescence-associated secretory phenotype (SASP), which affects neighboring cells. Recently, exosomes have been recognized as SASP factors, contributing to modulating a variety of cell functions. In particular, evidence suggests a key role for exosomal microRNAs in influencing many hallmarks of cancer. Herein, we demonstrate that doxorubicin treatment of MM cells leads to the enrichment of miR-433 into exosomes, which in turn induces bystander senescence. Our analysis reveals that the establishment of the senescent phenotype on neighboring MM cells is p53- and p21-independent and is related to CDK-6 down-regulation. Notably, miR-433-dependent senescence does not induce the up-regulation of activating ligands on MM cells. Altogether, our findings highlight the possibility of miR-433-enriched exosomes to reinforce doxorubicin-mediated cellular senescence.

Potential Regulation of miRNA-29 and miRNA-9 by Estrogens in Neurodegenerative Disorders: An Insightful Perspective

Finding a link between a hormone and microRNAs (miRNAs) is of great importance since it enables the adjustment of genetic composition or cellular functions without needing gene-level interventions. The dicer-mediated cleavage of precursor miRNAs is an interface link between miRNA and its regulators; any disruption in this process can affect neurogenesis. Besides, the hormonal regulation of miRNAs can occur at the molecular and cellular levels, both directly, through binding to the promoter elements of miRNAs, and indirectly, via regulation of the signaling effects of the post-transcriptional processing proteins. Estrogenic hormones have many roles in regulating miRNAs in the brain. This review discusses miRNAs, their detailed biogenesis, activities, and both the general and estrogen-dependent regulations. Additionally, we highlight the relationship between miR-29, miR-9, and estrogens in the nervous system. Such a relationship could be a possible etiological route for developing various neurodegenerative disorders.

miR-150-5p in neutrophil-derived extracellular vesicles associated with sepsis-induced cardiomyopathy in septic patients

INTRODUCTION

Early diagnosis and potential therapeutic targets of sepsis-induced cardiomyopathy (SIC) remain challenges clinically. Circulating extracellular vesicles from immune cells carrying crucial injurious mediators, including miRNAs in sepsis. However, the impacts of neutrophil-derived extracellular vesicles and their miRNAs in the SIC development are unknown.

OBJECTIVES

The present study focused on the in-depth miRNA expression profiles of neutrophil-derived extracellular vesicles and explored the potential molecular biomarkers during the process of SIC.

METHODS

Neutrophil-derived extracellular vesicles were isolated from the blood samples in three sepsis patients with or without cardiomyopathy on day 1 and day 3 after ICU admission in comparison with three healthy controls. miRNAs were determined by RNA sequencing. The closely related differentially expressed miRNAs with SIC were further validated through qRT-PCR in the other cohorts of sepsis patients with (30 patients) or without cardiomyopathy (20 patients) and the association between miRNAs and the occurrence or disease severity of septic cardiomyopathy were stratified with logistic regression analysis.

RESULTS

Sixty-eight miRNAs from neutrophil-derived extracellular vesicles were changed significantly between healthy controls and without septic cardiomyopathy patients (61 miRNAs upregulated and seven downregulated). Thirty-eight miRNAs were differentially expressed in the septic cardiomyopathy patients. 27 common differentially expressed miRNAs were found in both groups with similar kinetics (23 miRNAs upregulated and four downregulated). The enriched cellular signaling pathway mediated by miRNAs from sepsis to septic cardiomyopathy was the HIF-1 signaling system modulated septic inflammation. Using multivariate logistic regression analysis, miR-150-5p coupled with NT-pro BNP, LVEF, and SOFA score (AUC = 0.941) were found to be the independent predictors of septic cardiomyopathy.

CONCLUSION

miRNAs derived from neutrophil-derived extracellular vesicles play an important role in septic disease severity development towards cardiomyopathy. miR-150-5p may be a predictor of sepsis severity development but warrants further study.

Metabolites as extracellular vesicle cargo in health, cancer, pleural effusion, and cardiovascular diseases: An emerging field of study to diagnostic and therapeutic purposes

Extracellular vesicles (EVs) are highly diverse nanoscale membrane-bound structures released from different cell types into the extracellular environment. They play essential functions in cell signaling by transporting their cargo, such as proteins, RNA, DNA, lipids, metabolites, and small molecules, to recipient cells. It has recently been shown that EVs might modulate carcinogenesis by delivering cargo to recipient cells. Furthermore, recent discoveries revealed that changes in plasma-derived EV levels and cargo in subjects with metabolic diseases were documented by many researchers, suggesting that EVs might be a promising source of disease biomarkers. One of the cargos of EVs that has recently attracted the most attention is metabolites. The metabolome of these vesicles introduces a plethora of disease indicators; hence, examining the metabolomics of EVs detected in human biofluids would be an effective approach. On the other hand, metabolites have various roles in biological systems, including the production of energies, synthesizing macromolecules, and serving as signaling molecules and hormones. Metabolome rewiring in cancer and stromal cells is a characteristic of malignancy, but the current understanding of how this affects the metabolite composition and activity of tumor-derived EVs remains in its infancy. Since new findings and studies in the field of exosome biology and metabolism are constantly being published, it is likely that diagnostic and treatment techniques, including the use of exosome metabolites, will be launched in the coming years. Recent years have seen increased interest in the EV metabolome as a possible source for biomarker development. However, our understanding of the role of these molecules in health and disease is still immature. In this work, we have provided the latest findings regarding the role of metabolites as EV cargoes in the pathophysiology of diseases, including cancer, pleural effusion (PE), and cardiovascular disease (CVD). We also discussed the significance of metabolites as EV cargoes of microbiota and their role in host-microbe interaction. In addition, the latest findings on metabolites in the form of EV cargoes as biomarkers for disease diagnosis and treatment are presented in this study.

Profiling non-coding RNA expression in cerebrospinal fluid of amyotrophic lateral sclerosis patients

INTRODUCTION

Objective biomarkers for the fatal neurodegenerative disease amyotrophic lateral sclerosis or motor neuron disease (ALS/MND) are critical for diagnosis, drug development, clinical trials, and insight into disease pathology. Key candidates for biomarkers present in biofluids include non-coding RNA (ncRNA) transcripts including microRNA, piwi-interacting RNA and transfer RNA. To determine if the central nervous system was the source of the dysregulated ncRNA biomarkers we previously observed in serum, we sought to identify dysregulated ncRNA candidates in cerebrospinal fluid (CSF) which may provide new insight into the disease pathology.

METHODS AND MATERIALS

Small RNA sequencing (RNA-seq) was undertaken on CSF samples from healthy controls (n = 18), disease mimics (n = 8), and ALS patients (n = 40) in our Oxford Study for Biomarkers of ALS cohort, with RT-qPCR used to confirm their dysregulation.

RESULTS

We found a range of ncRNA that were dysregulated in the RNA-seq screen, but these failed to be validated or detected in some cases using reverse transcription-quantitative polymerase chain reaction (RT-qPCR). Additionally, our previously identified serum ncRNA biomarker showed no change in CSF or correlation to serum.

CONCLUSIONS

This study suggests the CSF may not be the source of dysregulated ncRNA in the serum and highlights the difficulty in identifying ncRNA in CSF as biomarkers for ALS.KEY MESSAGESIn this current study, we investigated the expression of non-coding RNA transcripts in the cerebrospinal fluid of ALS patients compared to healthy controls.RNA-seq identified dysregulated non-coding RNA transcripts, but these were not validated with RT-qPCR.We conclude that cerebrospinal fluid is not a suitable source of diagnostic biomarkers.

Platelet-derived extracellular vesicles encapsulate microRNA-34c-5p to ameliorate inflammatory response of coronary artery endothelial cells via PODXL-mediated P38 MAPK signaling pathway

BACKGROUND AND AIMS

Low-grade chronic inflammation was reported to serve as a distinctive pathophysiologic feature of coronary artery disease (CAD), the leading cause of death around the world. Herein, the current study aimed to explore whether and how microRNA-34c-5p (miR-34c-5p), a miRNA enriched in extracellular vesicles (EVs) originated from the activated platelet (PLT-EVs), affects the inflammation of human coronary artery endothelial cells (HCAECs).

METHODS AND RESULTS

HCAECs were established as an in vitro cell model using oxidized low-density lipoprotein (ox-LDL). miR-34c-5p, an abundant miRNA in PLT-EVs, can be transferred to HCAECs and target PODXL by binding to its 3'UTR. Gain- and loss-of-function experiments of miR-34c-5p and podocalyxin (PODXL) were performed in ox-LDL-induced HCAECs. Subsequently, HCAECs were subjected to co-culture with PLT-EVs, followed by detection of the expression patterns of key pro-inflammatory factors. Either miR-34c-5p mimic or PLT-EVs harboring miR-34c-5p attenuated the ox-LDL-evoked inflammation in HCAECs by suppressing interleukin-1β (IL-1β), IL-6 and tumor necrosis factor-α (TNF-α). By blocking the P38 MAPK signaling pathway, miR-34c-5p-mediated depletion of PODXL contributed to protection against ox-LDL-induced inflammation. In vitro findings were further validated by findings observed in ApoE knock-out mice. Additionally, miR-34c-5p in PLT-EVs showed an athero-protective role in the murine model.

CONCLUSION

Altogether, our findings highlighted that miR-34c-5p in PLT-EVs could alleviate inflammation response in HCAECs by targeting PODXL and inactivation of the P38 MAPK signaling pathway.

Effect of Crohn's disease mesenteric mesenchymal stem cells and their extracellular vesicles on T-cell immunosuppressive capacity

Crohn's disease (CD) is a chronic inflammatory disease of the gastrointestinal intestinal tract and has characteristic hypertrophic adipose changes observed in the mesentery. To better understand the role of the mesentery in the pathophysiology of Crohn's disease (CD), we evaluated the immunomodulatory potential of mesenchymal stem cells (MSCs) and their secreted extracellular vesicles (EVs) derived from Crohn's patients. MSCs and EVs were isolated from the mesentery and subcutaneous tissues of CD patients and healthy individuals subcutaneous tissues, and were analysed for differentiation, cytokine expression, self‐renewal and proliferation. The varying capacity of these tissue‐derived MSCs and EVs to attenuate T‐cell activation was measured in in vitro and an in vivo murine model. RNA sequencing of inflamed Crohn's disease mesentery tissue revealed an enrichment of T‐cell activation compared to non‐inflamed subcutaneous tissue. MSCs and MSC‐derived EVs isolated from Crohn's mesentery lose their ability to attenuate DSS‐induced colitis compared to subcutaneous tissue‐derived cell or EV therapy. We found that treatment with subcutaneous isolated MSCs and their EV product compared to Crohn's mesentery MSCs or EVs, the inhibition of T‐cell proliferation and IFN‐γ, IL‐17a production increased, suggesting a non‐inflamed microenvironment allows for T‐cell inhibition by MSCs/EVs. Our results demonstrate that Crohn's patient‐derived diseased mesentery tissue MSCs lose their immunosuppressive capacity in the treatment of colitis by distinct regulation of pathogenic T‐cell responses and/or T‐cell infiltration into the colon.

Natural killer (NK) cell-derived extracellular-vesicle shuttled microRNAs control T cell responses

Natural killer (NK) cells recognise and kill target cells undergoing different types of stress. NK cells are also capable of modulating immune responses. In particular, they regulate T cell functions. Small RNA next-generation sequencing of resting and activated human NK cells and their secreted EVs led to the identification of a specific repertoire of NK-EV-associated microRNAs and their post-transcriptional modifications signature. Several microRNAs of NK-EVs, namely miR-10b-5p, miR-92a-3p and miR-155-5p, specifically target molecules involved in Th1 responses. NK-EVs promote the downregulation of GATA3 mRNA in CD4⁺ T cells and subsequent TBX21 de-repression that leads to Th1 polarization and IFN-γ and IL-2 production. NK-EVs also have an effect on monocyte and moDCs function, driving their activation and increased presentation and co-stimulatory functions. Nanoparticle-delivered NK-EV microRNAs partially recapitulate NK-EV effects in mice. Our results provide new insights on the immunomodulatory roles of NK-EVs that may help to improve their use as immunotherapeutic tools.

Differential Expression of Serum Exosomal Hsa-miR-487b-3p in Progressive Vitiligo Before and After Systemic Corticosteroid Treatment

Background

Vitiligo is an acquired skin depigmentation disease. It can be misdiagnosed at an early stage and tend to relapse. Serum markers are essential to monitoring the progression of vitiligo. Exosomal miRNAs act as the communication mediator between melanocytes and immune cells. Our study aimed to use serum exosomal miRNAs as a reference for evaluating vitiligo progression.

Methods

The miRNAs were extracted from the serum exosomes of ten progressive vitiligo patients (before and after treatment) and ten healthy individuals. We profiled miRNAs expression by RNA sequencing and screened out potential miRNAs and plotted their receiver operating characteristic (ROC) curves to explore their sensitivity and specificity as prognostic biomarkers in vitiligo progression. We examined the correlation between miRNA expression and the lesion area. Different databases were used to predict gene targets of miRNAs, which were analyzed by gene ontology and Kyoto encyclopedia of genes and genomes (KEGG).

Results

Our results showed that 141 miRNAs were differentially expressed in serum exosomes of progressive vitiligo patients, and 365 miRNAs were differentially expressed in these patients after treatment compared to healthy individuals. The expression of hsa-miR-487b-3p was significantly lower in these patients compared to healthy individuals. Still, there was no difference in its levels in patients after corticosteroid treatment compared to healthy controls. ROC curve analysis (area under curve = 0.840) indicated that hsa-miR-487b-3p could serve as a biomarker for the prognosis of vitiligo progression. Its expression positively correlated with the lesion area. A total of 41 target genes of hsa-miR-487b-3p were predicted via different databases. KEGG pathways were enriched in phenylalanine metabolism, glycan degradation, and protein export.

Conclusion

Serum exosomal hsa-miR-487b-3p can be a biomarker to detect vitiligo progression. The predicted target genes of hsa-miR-487b-3p were enriched in catabolism. Thus, its in progressive vitiligo may accelerate catabolism in melanocytes and cause its impairment.

Emerging Role of Edible Exosomes-Like Nanoparticles (ELNs) as Hepatoprotective Agents

Liver diseases are responsible for over 2 million deaths each year and the number is rapidly increasing. There is a strong link between edibles, gut microbiota, liver fat and the liver damage. There are very limited therapeutic options for treatment specifically for Alcoholic liver disease (ALD) and Non-Alcoholic liver disease (NAFLD). Recently, identified Edible Exosomes-like nanoparticles (ELNs) are plant derived membrane bound particles, released by microvesicular bodies for cellular communication and regulate immune responses against many pathogens. Many studies have identified their role as hepatoprotective agent as they carry bioactive material as cargoes which are transferred to recipient cells and affect various biological functions in liver. They are also known to carry specific miRNA, which increases the copy number of beneficial bacteria and the production of lactic acid metabolites in gut and hence restrains from liver injury through portal vein. Few in-vitro studies also have been reported about the anti-inflammatory, anti-oxidant and detoxification properties of ELNs which again protects the liver. The properties such as small size, biocompatibility, stability, low toxicity and non-immunogenicity make ELNs as a better therapeutic option. But, till now, studies on the effect of ELNs as therapeutics are still at its infancy yet promising. Here we discuss about the isolation, characterization, their role in maintaining the gut microbiome and liver homeostasis. Also, we give an outline about the latest advances in ELNs modifications, its biological effects, limitations and we propose the future prospective of ELNs as therapeutics.

Circulating microRNA biomarkers in melanoma and non-melanoma skin cancer

INTRODUCTION

Skin cancer is the most common type of cancer and is classified in melanoma and non-melanoma cancers, which include basal cell, squamous cell and Merkel cell carcinoma. Specific microRNAs are dysregulated in each skin cancer type. MicroRNAs act as oncogene or tumor suppressor gene regulators and are actively released from tumor cells in the circulation. Cell-free microRNAs serve many, and possibly yet unexplored, functional roles, but their presence and abundance in the blood has been investigated as disease biomarker. Indeed, specific microRNAs can be isolated and quantified in the blood, usually in serum or plasma fractions, where they are uncommonly stable. MicroRNA levels reflect underlying conditions and have been associated with skin cancer presence, stage, evolution, or therapy efficacy.

AREAS COVERED

In this review, we summarize the state of the art on circulating microRNAs detectable in skin cancer patients including all the studies that performed microRNA identification and quantification in the circulation using appropriate sample size and statistics and providing detailed methodology, with a specific focus on diagnostic and prognostic biomarkers.

EXPERT OPINION

Circulating microRNAs display a relevant biomarker potential. We expect the development of methodological guidelines and standardized protocols for circulating miRNA quantification in clinical settings.

Leishmania survives by exporting miR-146a from infected to resident cells to subjugate inflammation

Leishmania donovani, the causative agent of visceral leishmaniasis, infects and resides within tissue macrophage cells. It is not clear how the parasite infected cells crosstalk with the noninfected cells to regulate the infection process. During infection, Leishmania adopts a dual strategy for its survival by regulating the intercellular transport of host miRNAs to restrict inflammation. The parasite, by preventing mitochondrial function of host cells, restricts the entry of liver cell derived miR-122-containing extracellular vesicles in infected macrophages to curtail the inflammatory response associated with miR-122 entry. On contrary, the parasite up-regulates the export of miR-146a from the infected macrophages. The miR-146a, associated with the extracellular vesicles released by infected cells, restricts miR-122 production in hepatocytes while polarizing neighbouring naïve macrophages to the M2 state by affecting the cytokine expression. On entering the recipient macrophages, miR-146a dominates the miRNA antagonist RNA-binding protein HuR to inhibit the expression of proinflammatory cytokine mRNAs having HuR-interacting AU-rich elements whereas up-regulates anti-inflammatory IL-10 by exporting the miR-21 to polarize the recipient cells to M2 stage.

Host miRNA and immune cell interactions: relevance in nano-therapeutics for human health

Around 2200 miRNA (microRNA) genes were found in the human genome. miRNAs are arranged in clusters within the genome and share the same transcriptional regulatory units. It has been revealed that approximately 50% of miRNAs elucidated in the genome are transcribed from non-protein-coding genes, and the leftover miRNAs are present in the introns of coding sequences. We are now approaching a stage in which miRNA diagnostics and therapies can be established confidently, and several commercial efforts are underway to carry these innovations from the bench to the clinic. MiRNAs control many of the significant cellular activities such as production, differentiation, growth, and metabolism. Particularly in the immune system, miRNAs have emerged as a crucial biological component during diseased state and homeostasis. miRNAs have been found to regulate inflammatory responses and autoimmune disorders. Moreover, each miRNA targets multiple genes simultaneously, making miRNAs promising tools as diagnostic biomarkers and as remedial targets. Still, one of the major obstacles in miRNA-based approaches is the achievement of specific and efficient systemic delivery of miRNAs. To overcome these challenges, nanoformulations have been synthesized to protect miRNAs from degradation and enhance cellular uptake. The current review deals with the miRNA-mediated regulation of the recruitment and activation of immune cells, especially in the tumor microenvironment, viral infection, inflammation, and autoimmunity. The nano-based miRNA delivery modes are also discussed here, especially in the context of immune modulation.

Extracellular vesicles cargo from head and neck cancer cell lines disrupt dendritic cells function and match plasma microRNAs

Extracellular vesicles (EVs) are mediators of the immune system response. Encapsulated in EVs, microRNAs can be transferred between cancer and immune cells. To define the potential effects of EVs originated from squamous cell carcinoma cells on immune system response, we performed microRNA profiling of EVs released from two distinct cell lines and treated dendritic cells derived from circulating monocytes (mono-DCs) with these EVs. We confirmed the internalization of EVs by mono-DCs and the down-regulation of microRNA mRNA targets in treated mono-DCs. Differences in surface markers of dendritic cells cultivated in the presence of EVs indicated that their content disrupts the maturation process. Additionally, microRNAs known to interfere with dendritic cell function, and detected in EVs, matched microRNAs from squamous cell carcinoma patients' plasma: miR-17-5p in oropharyngeal squamous cell carcinoma, miR-21 in oral squamous cell carcinoma, miR-16, miR-24, and miR-181a circulating in both oral and oropharyngeal squamous cell carcinoma, and miR-23b, which has not been previously described in plasma of head and neck squamous cell carcinoma, was found in plasma from patients with these cancer subtypes. This study contributes with insights on EVs in signaling between cancer and immune cells in squamous cell carcinoma of the head and neck.

Extracellular vesicles in anti-tumor immunity

To what extent extracellular vesicles (EVs) can impact anti-tumor immune responses has only started to get unraveled. Their nanometer dimensions, their growing number of subtypes together with the difficulties in defining their origin hamper their investigation. The existence of tumor cell lines facilitated advance in cancer EV understanding, while capturing information about phenotypes and functions of immune cell EVs in this context is more complex. The advent of immunotherapy with immune checkpoint inhibitors has further deepened the need to dissect the impact of EVs during immune activation and response, not least to contribute unraveling and preventing the generation of resistance occurring in the majority of patients. Here we discuss the factors that influence anddrive the immune response in cancer patients in the context of cancer therapeutics and the roles or possible functions that EVs can have in this scenario. With immune cell-derived EVs as leitmotiv, we will journey from EV discovery and subtypes through physiological and pathological functions, from similarities with tumor EVs to measures to revert detrimental consequences on immune responses to cancer.

MicroRNA-223 inhibits neutrophil extracellular traps formation through regulating calcium influx and small extracellular vesicles transmission

Modulation of miRNAs and neutrophil extracellular traps (NETs) formation are both implicated in inflammatory disorders. Adult-onset Still's disease (AOSD) is a systemic autoinflammatory disease with neutrophilic leukocytosis and unknown etiology. Although the NETs formation is elevated in AOSD patients, the regulatory roles of miRNAs in NETs formation in AOSD remains unclear. We revealed that the circulating levels of IL-18, NETs, and miR-223 were significantly higher in active AOSD patients, compared with inactive AOSD patients or healthy controls (P < 0.005). Moreover, IL-18 increased calcium influx into neutrophils, which led to mitochondrial ROS (mROS) production and NETs formation. Elevated levels of NETs-DNA could induce miR-223 expression in neutrophils through activating Toll-like receptor 9. The upregulated miR-223 expression in neutrophils suppressed mROS production by blocking calcium influx, and subsequently inhibited IL-18-mediated NETs formation. Besides, the increased neutrophil-derived exosomal miR-223 levels were observed in active AOSD patients compared with healthy controls (P < 0.005). Our in vitro assays demonstrated that the neutrophil-derived small extracellular vesicles carried miR-223, which could repress IL-18 production in macrophages. Together, these results suggest a fine-tuned mechanism between inflammatory (IL-18 induced NETs) and anti-inflammatory (miR-223) factors in AOSD. MiR-223, mROS inhibitors, and calcium channel blockers are the potential therapeutics for autoinflammatory diseases such as AOSD.

The pathogenic, therapeutic and diagnostic role of exosomal microRNA in the autoimmune diseases

Exosomes are a nano-vesicle surrounded by a bilipid layer that can release from almost all cells and could be detected in tissues and biological liquids. These vesicles contain lipids, proteins, and nucleic acids (including DNA, mRNA, and miRNA) inside and on the exosomes' surface constitute their content. Exosomes can transfer their cargo into the recipient cell, which can modify recipient cells' biological activities. Recently it has been deciphering that the miRNA pattern of exosomes reveals the cellular pathophysiological situation and modifies various biological processes. Increasing data regarding exosomes highlights that the exosomes and their cargo, especially miRNAs, are implicated in the pathophysiology of various disorders, such as autoimmune disease. The current evidence on the deciphering of mechanisms in which exosomal miRNAs contributed to autoimmunity was indicated that exosomal miRNA might hold information that can reprogram the function of many of the immune cells involved in autoimmune diseases' pathogenesis. In the present study, we summarized the pathogenic role of exosomal miRNAs in several autoimmune diseases, including myasthenia gravis (MG), psoriasis, inflammatory bowel disease (IBD), type 1 diabetes (T1D), multiple sclerosis (MS), systemic lupus erythematosus (SLE), rheumatoid arthritis (RA), Sjogren's Syndrome (SS), systemic sclerosis (SSc), vitiligo, and autoimmune thyroid diseases (AITD). Moreover, in this work, we present evidence of the potential role of exosomal miRNAs as therapeutic and diagnostic agents in autoimmune diseases.

Exosomes Derived From Heat Stroke Cases Carry miRNAs Associated With Inflammation and Coagulation Cascade

The pathological mechanism underlying heat stroke (HS) is associated with the dysbalanced inflammation and coagulation cascade. Cell-derived circulating extracellular vesicles (EVs), as a novel pathway mediating intercellular communication, are associated with the immune response and inflammation in critical inflammatory syndromes, such as sepsis. Although these vesicles contain genetic material correlated with their biological function, their molecular cargo during HS remains unknown. In this study, we evaluate the presence of microRNAs (miRNAs) and messenger RNAs (mRNAs) associated with inflammatory responses and coagulation cascade in exosomes of patients with HS. Blood samples were collected from three patients with HS at the time of admission to the intensive care unit; three healthy volunteers were selected as control. Exosomes were isolated using ultracentrifugation, and their miRNA content was profiled using next-generation sequencing; mRNA content was evaluated using qPCR array. Compared with those from healthy volunteers, exosomes from patients with HS showed substantial changes in the expression of 202 exosomal miRNAs (154 upregulated and 48 downregulated miRNAs). The most upregulated miRNAs included miR-511-3p, miR-122-5p, miR-155-3p, miR-1290, and let7-5p, whereas the most downregulated ones included miR-150-3p, 146a-5p, and 151a-3p. Gene ontology enrichment of the miRNAs of patients with HS compared with control subjects were associated mostly with inflammatory response, including T cell activation, B cell receptor signaling, dendritic cell chemotaxis and leukocyte migration, and platelet activation and blood coagulation. The identified miRNAs were primarily enriched to the signal transduction pathways namely, T cell receptor signaling, Ras signaling, chemokine signaling, platelet activation, and leukocyte transendothelial migration, all of which are associated with inflammation and hemostasis. Multiple targeted mRNAs associated with the inflammatory response, blood coagulation, and platelet activation were further verified in serum exosomes. Exosomes from patients with HS convey miRNAs and mRNAs associated with pathogenic pathways, including inflammatory response and coagulation cascade. Exosomes may represent a novel mechanism for intercellular communication during HS.

Critical Review of the Evolution of Extracellular Vesicles' Knowledge: From 1946 to Today

Extracellular vesicles (EVs) are a family of particles/vesicles present in blood and body fluids, composed of phospholipid bilayers that carry a variety of molecules that can mediate cell communication, modulating crucial cell processes such as homeostasis, induction/dampening of inflammation, and promotion of repair. Their existence, initially suspected in 1946 and confirmed in 1967, spurred a sharp increase in the number of scientific publications. Paradoxically, the increasing interest for EV content and function progressively reduced the relevance for a precise nomenclature in classifying EVs, therefore leading to a confusing scientific production. The aim of this review was to analyze the evolution of the progress in the knowledge and definition of EVs over the years, with an overview of the methodologies used for the identification of the vesicles, their cell of origin, and the detection of their cargo. The MISEV 2018 guidelines for the proper recognition nomenclature and ways to study EVs are summarized. The review finishes with a “more questions than answers” chapter, in which some of the problems we still face to fully understand the EV function and potential as a diagnostic and therapeutic tool are analyzed.

Lipopolysaccharide-Induced Exosomal miR-146a Is Involved in Altered Expression of Alzheimer's Risk Genes Via Suppression of TLR4 Signaling

Repeated exposure to toll-like receptor 4 (TLR4) ligands, such as lipopolysaccharide (LPS), reduces responses of monocytes/macrophages to LPS (LPS/endotoxin tolerance). Microglial exposure to Aβ deposits, a TLR4 ligand, may cause "Aβ/LPS tolerance," leading to decreased Aβ clearance. We demonstrated that microglial activation by LPS is diminished in Aβ deposit-bearing 12-month-old model mice of Alzheimer's disease (AD), compared with non-AD mice and Aβ deposit-free 2-month-old AD mice. Because miR-146a plays a predominant role in inducing TLR tolerance in macrophages and because miR-146a in extracellular vesicles (EVs) shed by inflammatory macrophages increases in circulation, we investigated potential roles of miR-146a and inflammatory EVs in inducing TLR tolerance in microglia and in altering expression of inflammatory AD risk genes. We found that miR-146a upregulation induces TLR tolerance and alters expression of inflammatory AD risk genes in response to LPS treatment in BV2 microglia. LPS brain injection altered expression of the AD risk genes in 12-month-old AD mice but not in non-AD littermates. EVs from inflammatory macrophages polarize BV2 microglia to M1 phenotype and induce TLR tolerance. Microglia exposed to Aβ in the brain show reduced cytokine responses to systemic inflammation due to peripheral LPS injection, indicating TLR/Aβ tolerance in microglia. Our results suggest that increased miR-146a induces microglial Aβ/LPS tolerance and that circulating EVs shed by inflammatory macrophages contribute to microglial Aβ/LPS tolerance, leading to reduced Aβ clearance. Our study also suggests that altered expression of inflammatory AD risk genes may contribute to AD development via the same molecular mechanism underlying LPS tolerance.

Extracellular Vesicles: An Emerging Mechanism Governing the Secretion and Biological Roles of Tenascin-C

ECM composition and architecture are tightly regulated for tissue homeostasis. Different disorders have been associated to alterations in the levels of proteins such as collagens, fibronectin (FN) or tenascin-C (TnC). TnC emerges as a key regulator of multiple inflammatory processes, both during physiological tissue repair as well as pathological conditions ranging from tumor progression to cardiovascular disease. Importantly, our current understanding as to how TnC and other non-collagen ECM components are secreted has remained elusive. Extracellular vesicles (EVs) are small membrane-bound particles released to the extracellular space by most cell types, playing a key role in cell-cell communication. A broad range of cellular components can be transported by EVs (e.g. nucleic acids, lipids, signalling molecules and proteins). These cargoes can be transferred to target cells, potentially modulating their function. Recently, several extracellular matrix (ECM) proteins have been characterized as bona fide EV cargoes, exosomal secretion being particularly critical for TnC. EV-dependent ECM secretion might underpin diseases where ECM integrity is altered, establishing novel concepts in the field such as ECM nucleation over long distances, and highlighting novel opportunities for diagnostics and therapeutic intervention. Here, we review recent findings and standing questions on the molecular mechanisms governing EV–dependent ECM secretion and its potential relevance for disease, with a focus on TnC.

The Anticancer Effects of Flavonoids through miRNAs Modulations in Triple-Negative Breast Cancer

Triple- negative breast cancer (TNBC) incidence rate has regularly risen over the last decades and is expected to increase in the future. Finding novel treatment options with minimum or no toxicity is of great importance in treating or preventing TNBC. Flavonoids are new attractive molecules that might fulfill this promising therapeutic option. Flavonoids have shown many biological activities, including antioxidant, anti-inflammatory, and anticancer effects. In addition to their anticancer effects by arresting the cell cycle, inducing apoptosis, and suppressing cancer cell proliferation, flavonoids can modulate non-coding microRNAs (miRNAs) function. Several preclinical and epidemiological studies indicate the possible therapeutic potential of these compounds. Flavonoids display a unique ability to change miRNAs' levels via different mechanisms, either by suppressing oncogenic miRNAs or activating oncosuppressor miRNAs or affecting transcriptional, epigenetic miRNA processing in TNBC. Flavonoids are not only involved in the regulation of miRNA-mediated cancer initiation, growth, proliferation, differentiation, invasion, metastasis, and epithelial-to-mesenchymal transition (EMT), but also control miRNAs-mediated biological processes that significantly impact TNBC, such as cell cycle, immune system, mitochondrial dysregulation, modulating signaling pathways, inflammation, and angiogenesis. In this review, we highlighted the role of miRNAs in TNBC cancer progression and the effect of flavonoids on miRNA regulation, emphasizing their anticipated role in the prevention and treatment of TNBC.

Inflammation and biomaterials: role of the immune response in bone regeneration by inorganic scaffolds

The regulatory role of the immune system in maintaining bone homeostasis and restoring its functionality, when disturbed due to trauma or injury, has become evident in recent years. The polarization of macrophages, one of the main constituents of the immune system, into the pro-inflammatory or anti-inflammatory phenotype has great repercussions for cellular crosstalk and the subsequent processes needed for proper bone regeneration such as angiogenesis and osteogenesis. In certain scenarios, the damaged osseous tissue requires the placement of synthetic bone grafts to facilitate the healing process. Inorganic biomaterials such as bioceramics or bioactive glasses are the most widely used due to their resemblance to the mineral phase of bone and superior osteogenic properties. The immune response of the host to the inorganic biomaterial, which is of an exogenous nature, might determine its fate, leading either to active bone regeneration or its failure. Therefore, various strategies have been employed, like the modification of structural/chemical features or the incorporation of bioactive molecules, to tune the interplay with the immune cells. Understanding how these particular modifications impact the polarization of macrophages and further osteogenic and osteoclastogenic events is of great interest in view of designing a new generation of osteoimmunomodulatory materials that support the regeneration of osseous tissue during all stages of bone healing.

Clinical Translational Potentials of Stem Cell-Derived Extracellular Vesicles in Type 1 Diabetes

Type 1 diabetes (T1D) is an organ-specific disease characterized by the deficiency of insulin caused by the autoimmune destruction of pancreatic islet β cells. Stem cell-based therapies play essential roles in immunomodulation and tissue regeneration, both of which hold great promise for treating many autoimmune dysfunctions. However, their clinical translational potential has been limited by ethical issues and cell transplant rejections. Exosomes are small extracellular vesicles (EVs) released by almost all types of cells, performing a variety of cell functions through the delivery of their molecular contents such as proteins, DNAs, and RNAs. Increasing evidence suggests that stem cell-derived EVs exhibit similar functions as their parent cells, which may represent novel therapeutic agents for the treatment of autoimmune diseases including T1D. In this review, we summarize the current research progresses of stem cell-derived EVs for the treatment of T1D.

The Functional Heterogeneity of Neutrophil-Derived Extracellular Vesicles Reflects the Status of the Parent Cell

Similar to other cell types, neutrophilic granulocytes also release extracellular vesicles (EVs), mainly medium-sized microvesicles/microparticles. According to published data, authors have reached a consensus on the physical parameters (size, density) and chemical composition (surface proteins, proteomics) of neutrophil-derived EVs. In contrast, there is large diversity and even controversy in the reported functional properties. Part of the discrepancy may be ascribed to differences in the viability of the starting cells, in eliciting factors, in separation techniques and in storage conditions. However, the most recent data from our laboratory prove that the same population of neutrophils is able to generate EVs with different functional properties, transmitting pro-inflammatory or anti-inflammatory effects on neighboring cells. Previously we have shown that Mac-1 integrin is a key factor that switches anti-inflammatory EV generation into pro-inflammatory and antibacterial EV production. This paper reviews current knowledge on the functional alterations initiated by neutrophil-derived EVs, listing their effects according to the triggering agents and target cells. We summarize the presence of neutrophil-derived EVs in pathological processes and their perspectives in diagnostics and therapy. Finally, the functional heterogeneity of differently triggered EVs indicates that neutrophils are capable of producing a broad spectrum of EVs, depending on the environmental conditions prevailing at the time of EV genesis.

Extracellular Vesicles in HTLV-1 Communication: The Story of an Invisible Messenger

Human T-cell lymphotropic virus type 1 (HTLV-1) infects 5-10 million people worldwide and is the causative agent of adult T-cell leukemia/lymphoma (ATLL) and HTLV-1-associated myelopathy/tropical spastic paraparesis (HAM/TSP) as well as other inflammatory diseases. A major concern is that the most majority of individuals with HTLV-1 are asymptomatic carriers and that there is limited global attention by health care officials, setting up potential conditions for increased viral spread. HTLV-1 transmission occurs primarily through sexual intercourse, blood transfusion, intravenous drug usage, and breast feeding. Currently, there is no cure for HTLV-1 infection and only limited treatment options exist, such as class I interferons (IFN) and Zidovudine (AZT), with poor prognosis. Recently, small membrane-bound structures, known as extracellular vesicles (EVs), have received increased attention due to their potential to carry viral cargo (RNA and proteins) in multiple pathogenic infections (i.e., human immunodeficiency virus type I (HIV-1), Zika virus, and HTLV-1). In the case of HTLV-1, EVs isolated from the peripheral blood and cerebral spinal fluid (CSF) of HAM/TSP patients contained the viral transactivator protein Tax. Additionally, EVs derived from HTLV-1-infected cells (HTLV-1 EVs) promote functional effects such as cell aggregation which enhance viral spread. In this review, we present current knowledge surrounding EVs and their potential role as immune-modulating agents in cancer and other infectious diseases such as HTLV-1 and HIV-1. We discuss various features of EVs that make them prime targets for possible vehicles of future diagnostics and therapies.

Extracellular Vesicles Orchestrate Immune and Tumor Interaction Networks

Simple Summary

Significant strides have been made to describe the pervasive role of extracellular vesicles (EVs) in health and disease. This work provides an insightful and unifying mechanistic understanding of EVs in immunity and tumorigenesis. This is achieved by dissecting the role of EVs within the continuum of immune cell physiology, immune–infection responses, and the immune–tumor microenvironment. Our work synthesizes important topical findings on immune EV signaling in mediating immune–tumor interaction networks.

Abstract

Extracellular vesicles (EVs) are emerging as potent and intricate intercellular communication networks. From their first discovery almost forty years ago, several studies have bolstered our understanding of these nano-vesicular structures. EV subpopulations are now characterized by differences in size, surface markers, cargo, and biological effects. Studies have highlighted the importance of EVs in biology and intercellular communication, particularly during immune and tumor interactions. These responses can be equally mediated at the proteomic and epigenomic levels through surface markers or nucleic acid cargo signaling, respectively. Following the exponential growth of EV studies in recent years, we herein synthesize new aspects of the emerging immune–tumor EV-based intercellular communications. We also discuss the potential role of EVs in fundamental immunological processes under physiological conditions, viral infections, and tumorigenic conditions. Finally, we provide insights on the future prospects of immune–tumor EVs and suggest potential avenues for the use of EVs in diagnostics and therapeutics.

Mesenchymal stem cells and acellular products attenuate murine induced colitis

Background

Mesenchymal stem cells (MSCs) are a well-established immunomodulatory agent which can also promote tissue repair and regeneration. Recent studies have demonstrated MSCs as a novel therapeutic for inflammatory bowel disease (IBD), a chronic idiopathic inflammatory disorder of the gastrointestinal tract. However, the precise role of MSCs in regulating immune responses is controversial, and its significance in the pathogenesis remains IBD undefined. In addition, MSCs’ acellular product, extracellular vesicles (EVs), may also play an important role in the armamentarium of therapeutics, but how EVs compare to MSCs remains unknown due to the lack of side-by-side comparative investigation. We herein compared MSCs and MSC-derived EVs for the treatment of IBD using a DSS-induced colitis model.

Methods

A DSS-induced colitis model was used. At day 4, mice received adipose-derived MSCs, MSC-derived EVs, or placebo. Weight loss, stool consistency, and hematochezia was charted. At day 8, murine colons were harvested, histologic analysis performed, and serum/tissue cytokine analysis conducted.

Results

MSCs and EVs demonstrated equivalent immunosuppressive function in DSS-treated mice through decreased colonic lymphocyte infiltration and attenuated disease severity after both MSC and EV treatment. Furthermore, both MSCs and EVs have an equivalent ability to inhibit inflammation in the DSS colitis model by inhibiting JAK, JNK 1/2, and STAT3 signaling.

Conclusions

These results suggest that (i) both MSCs and EVs are effective therapeutic candidates for a DSS-induced mouse colitis model, (ii) MSCs and EVs have similar immunosuppressive and anti-inflammatory functions, and (iii) EVs may present a novel future therapeutic for the treatment of IBD.

Immune Regulation by Dendritic Cell Extracellular Vesicles in Cancer Immunotherapy and Vaccines

Extracellular vesicles (EVs) play a crucial role in intercellular communication as vehicles for the transport of membrane and cytosolic proteins, lipids, and nucleic acids including different RNAs. Dendritic cells (DCs)-derived EVs (DEVs), albeit variably, express major histocompatibility complex (MHC)-peptide complexes and co-stimulatory molecules on their surface that enable the interaction with other immune cells such as CD8⁺ T cells, and other ligands that stimulate natural killer (NK) cells, thereby instructing tumor rejection, and counteracting immune-suppressive tumor microenvironment. Malignant cells oppose this effect by secreting EVs bearing a variety of molecules that block DCs function. For instance, tumor-derived EVs (TDEVs) can impair myeloid cell differentiation resulting in myeloid-derived suppressor cells (MDSCs) generation. Hence, the unique composition of EVs makes them suitable candidates for the development of new cancer treatment approaches including prophylactic vaccine targeting oncogenic pathogens, cancer vaccines, and cancer immunotherapeutics. We offer a perspective from both cell sides, DCs, and tumor cells, on how EVs regulate the antitumor immune response, and how this translates into promising therapeutic options by reviewing the latest advancement in DEV-based cancer therapeutics.

Usefulness of circulating microRNAs miR-146a and miR-16-5p as prognostic biomarkers in community-acquired pneumonia

Introduction

Patients with community-acquired pneumonia (CAP) undergo a dysregulated host response that is related to mortality. MicroRNAs (miRNAs) participate in this response, but their expression pattern and their role as biomarkers in CAP have not been fully characterized.

Methods

A prospective observational study was performed in a cohort of 153 consecutive patients admitted to hospital with CAP. Clinical and analytical variables were collected, and the main outcome variable was 30-day mortality. Small RNA was purified from plasma of these patients obtained on the first day of admission, and miRNA expression was analyzed by RT-PCR. Univariate and multivariate analyses were carried out through the construction of a logistic regression model. The proposed model was compared with established prognostic clinical scales using ROC curve analysis.

Results

The mean age of the patients included was 74.7 years [SD 15.9]. Their mean PSI was 100.9 [SD 34.6] and the mean modified Charlson index was 2.9 [SD 3.0]. Both miR-146a and miR-16-5p showed statistically significant association with 30-day mortality after admission due to CAP (1.10 vs. 0.23 and 51.74 vs. 35.23, respectively), and this association remained for miR-16-5p in the multivariate analysis adjusted for age, gender and history of bronchoaspiration (OR 0.95, p = 0.021). The area-under-the-curve (AUC) of our adjusted multivariate model (AUC = 0.954 95%CI [0.91–0.99]), was better than those of prognostic scales such as PSI (AUC = 0.799 [0.69–0.91]) and CURB-65 (AUC = 0.722 [0.58–0.86]).

Conclusions

High levels of miR-146a-5p and miR-16-5p upon admission due to CAP are associated with lower mortality at 30 days of follow-up. Both miRNAs could be used as biomarkers of good prognosis in subjects hospitalized with CAP.

The Immunomodulatory Signature of Extracellular Vesicles From Cardiosphere-Derived Cells: A Proteomic and miRNA Profiling

Experimental data demonstrated that the regenerative potential and immunomodulatory capacity of cardiosphere-derived cells (CDCs) is mediated by paracrine mechanisms. In this process, extracellular vesicles derived from CDCs (EV-CDCs) are key mediators of their therapeutic effect. Considering the future applicability of these vesicles in human diseases, an accurate preclinical-to-clinical translation is needed, as well as an exhaustive molecular characterization of animal-derived therapeutic products. Based on that, the main goal of this study was to perform a comprehensive characterization of proteins and miRNAs in extracellular vesicles from porcine CDCs as a clinically relevant animal model. The analysis was performed by identification and quantification of proteins and miRNA expression profiles. Our results revealed the presence of clusters of immune-related and cardiac-related molecular biomarkers in EV-CDCs. Additionally, considering that priming stem cells with inflammatory stimuli may increase the therapeutic potential of released vesicles, here we studied the dynamic changes that occur in the extracellular vesicles from IFNγ-primed CDCs. These analyses detected statistically significant changes in several miRNAs and proteins. Notably, the increase in interleukin 6 (IL6) protein, as well as the increase in mir-125b (that targets IL6 receptor) was especially relevant. These results suggest a potential involvement of EV-CDCs in the regulation of the IL6/IL6R axis, with implications in inflammatory-mediated diseases.

A Circulating MicroRNA Profile in a Laser-Induced Mouse Model of Choroidal Neovascularization

Choroidal neovascularization (CNV) is a pathological process in which aberrant blood vessels invade the subretinal space of the mammalian eye. It is a characteristic feature of the prevalent neovascular age-related macular degeneration (nAMD). Circulating microRNAs (cmiRNAs) are regarded as potentially valuable biomarkers for various age-related diseases, including nAMD. Here, we investigated cmiRNA expression in an established laser-induced CNV mouse model. Upon CNV induction in C57Bl/6 mice, blood-derived cmiRNAs were initially determined globally by RNA next generation sequencing, and the most strongly dysregulated cmiRNAs were independently replicated by quantitative reverse transcription PCR (RT-qPCR) in blood, retinal, and retinal pigment epithelium (RPE)/choroidal tissue. Our findings suggest that two miRNAs, mmu-mir-486a-5p and mmur-mir-92a-3p, are consistently dysregulated during CNV formation. Furthermore, in functional in vitro assays, a significant impact of mmu-mir-486a-5p and mmu-mir-92a-3p on murine microglial cell viability was observed, while mmu-mir-92a-3p also showed an impact on microglial mobility. Taken together, we report a robust dysregulation of two miRNAs in blood and RPE/choroid after laser-induced initiation of CNV lesions in mice, highlighting their potential role in pathology and eventual therapy of CNV-associated complications.

Inducible Polarized Secretion of Exosomes in T and B Lymphocytes

Exosomes are extracellular vesicles (EV) of endosomal origin (multivesicular bodies, MVB) constitutively released by many different eukaryotic cells by fusion of MVB to the plasma membrane. However, inducible exosome secretion controlled by cell surface receptors is restricted to very few cell types and a limited number of cell surface receptors. Among these, exosome secretion is induced in T lymphocytes and B lymphocytes when stimulated at the immune synapse (IS) via T-cell receptors (TCR) and B-cell receptors (BCR), respectively. IS formation by T and B lymphocytes constitutes a crucial event involved in antigen-specific, cellular, and humoral immune responses. Upon IS formation by T and B lymphocytes with antigen-presenting cells (APC), the convergence of MVB towards the microtubule organization center (MTOC), and MTOC polarization to the IS, are involved in polarized exosome secretion at the synaptic cleft. This specialized mechanism provides the immune system with a finely-tuned strategy to increase the specificity and efficiency of crucial secretory effector functions of B and T lymphocytes. As inducible exosome secretion by antigen-receptors is a critical and unique feature of the immune system this review considers the study of the traffic events leading to polarized exosome secretion at the IS and some of their biological consequences.

Adenosine leakage from perforin-burst extracellular vesicles inhibits perforin secretion by cytotoxic T-lymphocytes

Extracellular vesicles (EVs) in the tumor microenvironment facilitate intercellular communication. Cancer cell-derived EVs act as an immunosuppressor by transporting cargos and presenting transmembrane proteins. By contrast, CD8+ cytotoxic T-lymphocytes (CTLs) exert anti-cancer cytotoxicity via the pore-forming protein perforin. Here, we hypothesize that although EVs are destroyed by perforin, cancer cell-derived EVs might possess mechanisms that enable them to avoid this destruction. We used a breast cancer cell line, MDA-MB-231-luc-D3H2LN (D3H2LN), to generate EVs. Destruction of the EVs by perforin was demonstrated visually using atomic force microscopy. To investigate immunosuppressive metabolites within cancer cell-derived EVs, we performed metabolomic profiling of EVs from D3H2LN cells cultured for 48 h with or without IFN-γ, which induces metabolic changes in the cells. We found that both types of EV from IFN-γ treated D3H2LN cells and non-treated D3H2LN cells contained adenosine, which has immunosuppressive effects. When we exposed cancer cell-derived EVs to CTLs, perforin secretion by CTLs fell significantly. In addition, the decreases in perforin secretion were ameliorated by treatment with adenosine deaminase, which degrades extracellular adenosine. Taken together, these results suggest that after perforin secreted by CTLs disrupts the membrane of EVs, adenosine released from the EVs acts as an immunosuppressive metabolite by binding to the adenosine receptor on the CTL membrane. This mechanism provides a novel survival strategy using cancer cell-derived EVs.

MicroRNA binding site polymorphism in inflammatory genes associated with colorectal cancer: literature review and bioinformatics analysis

Inflammation, among environmental risk factors, is one of the most important contributors to colorectal cancer (CRC) development. In this way, studies revealed that the incidence of CRC in inflammatory bowel disease patients is up to 60% higher than the general population. MicroRNAs (miRNAs), small noncoding RNA molecules, have attracted excessive attention due to their fundamental role in various aspects of cellular biology, such as inflammation by binding to the 3'-untranslated regions (3'-UTR) of pro and anti-inflammatory genes. Based on multiple previous studies, SNPs at 3'-UTR can affect miRNA recognition elements by changing the thermodynamic features and secondary structure. This effect can be categorized, based on the number of changes, into four groups, including break, decrease, create, and enhance. In this paper, we will focus on functional variants in miRNA binding sites in inflammatory genes, which can modulate the risk of CRC by both investigating previous studies, regarding miRSNPs in inflammatory genes associated with CRC and recruiting in silico prediction algorithms to report putative miRSNPs in 176 inflammatory genes. In our analysis, we achieved 110 miRSNPs in 3'-UTR of 67 genes that seem good targets for future researches.

Transfer of extracellular vesicle-microRNA controls germinal center reaction and antibody production

Intercellular communication orchestrates effective immune responses against disease‐causing agents. Extracellular vesicles (EVs) are potent mediators of cell–cell communication. EVs carry bioactive molecules, including microRNAs, which modulate gene expression and function in the recipient cell. Here, we show that formation of cognate primary T‐B lymphocyte immune contacts promotes transfer of a very restricted set of T‐cell EV‐microRNAs (mmu‐miR20‐a‐5p, mmu‐miR‐25‐3p, and mmu‐miR‐155‐3p) to the B cell. Transferred EV‐microRNAs target key genes that control B‐cell function, including pro‐apoptotic BIM and the cell cycle regulator PTEN. EV‐microRNAs transferred during T‐B cognate interactions also promote survival, proliferation, and antibody class switching. Using mouse chimeras with Rab27KO EV‐deficient T cells, we demonstrate that the transfer of small EVs is required for germinal center reaction and antibody production in vivo, revealing a mechanism that controls B‐cell responses via the transfer of EV‐microRNAs of T‐cell origin. These findings also provide mechanistic insight into the Griscelli syndrome, associated with a mutation in the Rab27a gene, and might explain antibody defects observed in this pathogenesis and other immune‐related and inflammatory disorders.

Targetting Exosomes as a New Biomarker and Therapeutic Approach for Alzheimer's Disease

Alzheimer’s disease (AD) is a neurodegenerative disease that mainly occurs in old age and involves progressive cognitive impairment. AD has become a major global issue for public health, with approximately 24 million people currently affected by the disease. Estimates indicted that this number will quadruple by 2050. Because of the high incidence of AD, there is an urgent need to develop new strategies to diagnose and treat AD. Many recent studies have indicated the multiple, yet somewhat controversial, roles of exosomes in AD. Although the underlying mechanisms by which exosomes play a role in AD are still unknown, current evidence suggests that exosomes can carry and spread toxic amyloid-beta, and hyperphosphorylated tau, between cells, and then induce apoptosis, thus contributing to the loss of neurons. In addition, exosomes appear to possess the ability to reduce brain amyloid-beta, and tau hyperphosphorylation, and transfer neuroprotective substances between neural cells. The accumulating data brings hope that the application of exosomes may be helpful for early diagnostics and the identification of new therapeutic targets for AD. Here, we summarized the various roles of exosomes, and how they might relate to the pathogenesis of AD. We also highlight the potential application of exosomes as a therapeutic option in AD therapy.

Exosomes in Cancer: Circulating Immune-Related Biomarkers

Exosomes, the smallest vesicles (30–100 nm) among multivesicular bodies, are released by all body cells including tumor cells. The cargo they transfer plays an important role in intercellular communication. Tumor-derived exosomes (TEXs) maintain interactions between cancer cells and the microenvironment. Emerging evidence suggests that tumor cells release a large number of exosomes, which may not only influence proximal tumor cells and stromal cells in the local microenvironment but can also exert systemic effects as they are circulating in the blood. TEXs have been shown to boost tumor growth promote progression and metastatic spread via suppression or modification of the immune response towards cancer cells, regulation of tumor neo-angiogenesis, pre-metastatic niche formation, and therapy resistance. In addition, recent studies in patients with cancer suggest that TEXs could serve as tumor biomarker reflecting partially the genetic and molecular content of the parent cancer cell (i.e., as a so-called “liquid biopsy”). Furthermore, recent studies have demonstrated that exosomes may have immunotherapeutic applications, or can act as a drug delivery system for targeted therapies with drugs and biomolecules.

Stem Cell Ophthalmology Treatment Study (SCOTS): bone marrow derived stem cells in the treatment of Dominant Optic Atrophy

Background

We report the results of 6 patients with Dominant Optic Atrophy (DOA) who met inclusion criteria and were treated in the Stem Cell Ophthalmology Treatment Study (SCOTS). SCOTS/SCOTS 2 is an Institutional Review Board approved and NIH registered (NCT03011541) clinical study that uses autologous bone marrow derived stem cells (BMSC) in the treatment of optic nerve and retinal disease.

Methods

This is an open label, non-randomized clinical study using natural history of the disease as the comparator. BMSC were separated from aspirated autologous bone marrow with minimal manipulation using an FDA cleared Class II medical device. Patients were treated with combinations of retrobulbar, subtenons, intravitreal or subretinal placement of BMSC followed by intravenous injection of BMSC depending on the arm of the study chosen. There were no surgical complications.

Results

Of the patients treated, 83.3% (5 of 6 patients) experienced visual improvements and in all of these cases both eyes improved. Ten eyes or 83.3% experienced gains in visual acuity with a median improvement of 2.125 Snellen lines, or approximately 10.63 letters. Two eyes were considered unchanged compared to longstanding measurements. Using LogMAR, the average improvement in vision for all eyes was 29.5%. The averagevisual acuity increasein eyes that improved was 33.3%. Findings were statistically significant with P<0.001.

Conclusions

Using autologous BMSC per protocols developed in the SCOTS/SCOTS 2 clinical studies resulted in statistically significant visual acuity improvements in patients with DOA or Kjers Optic Neuropathy. Improvements occurred in 83.3% of eyes and averaged 29.5%. Mitochondrial transfer and neuroprotective exosome secretions from the BMSC may have been key to the improvements observed in this mitochondrial disease.

Cancer-Derived Extracellular Vesicle-Associated MicroRNAs in Intercellular Communication: One Cell's Trash Is Another Cell's Treasure

Several non-protein-coding genomic regions, previously marked as "junk DNA", have been reported to be transcriptionally active, giving rise to non-coding RNA species implicated in fundamental biological and pathological processes. In particular, microRNAs (miRNAs), a class of small non-coding RNAs mediating post-transcriptional gene silencing, are causally involved in several human diseases, including various cancer types. Extracellular vesicles (EVs) are membranous structures physiologically released by most cell types. Initially, they were considered a "waste-removal" mechanism, through which cells could dispose unnecessary material and organelles. It is now widely demonstrated that EVs also play a critical role in intercellular communication, mediating the horizontal transfer of lipids, proteins, and genetic material. A paradigm shift in the biology of miRNAs was represented by the discovery that EVs, especially from cancer cells, contain miRs. EV-associated miRs act as autocrine, paracrine and endocrine factors, participating in cancer pathogenesis by modulating intercellular communication. Noteworthy, these formerly neglected molecules are now considered the next generation of cancer "theranostic" tools, with strong clinical relevance. In this review, we aim to summarize the most recent findings regarding EV-associated miRs in cancer pathogenesis and in the development of novel anti-neoplastic diagnostic and therapeutic approaches.

Conditioned Medium of Mesenchymal Stromal Cells: A New Class of Therapeutics

Mesenchymal stromal cell (MSCs) represent a class of biologics with the prospects for employment as immunomodulatory, tissue-protective, and regenerative therapeutics. In parallel with cellular therapy, cell-free therapy based on MSC-secreted bioactive factors is being actively developed. MSCs secrete a variety of protein, peptide, RNA, and lipid mediators which can be concentrated, frozen, or even lyophilized without loss of activity, which gives them a certain advantage over cellular products requiring liquid nitrogen storage and infrastructure to revive frozen cells. This review (i) describes currently conducted clinical trials of cell-free products containing MSC secretome; (ii) summarizes main approaches to the generation and characterization of conditioned media concentrates and extracellular vesicle isolates; (iii) analyzes a variety of preclinical studies where effectiveness of secretome products has been shown; and (iv) summarizes current knowledge about secretome bioactive components obtained by analysis of in vivo models testing the therapeutic potential of the MSC secretome.

Stem Cell Ophthalmology Treatment Study (SCOTS): bone marrow derived stem cells in the treatment of Usher syndrome

Background

Usher syndrome is the most common form of syndromic retinitis pigmentosa and includes types I, II, and III with varying degrees of hearing loss. We present results of 10 eyes with Usher syndrome treated with autologous bone marrow derived stem cells (BMSC) within the Stem Cell Ophthalmology Treatment Study (SCOTS).

Methods

Preoperative Snellen visual acuities ranged from 20/30-1 to 20/400 with the average pre-operative Snellen acuity approximately 20/85 and the average logarithm of the minimum angle of resolution (LogMAR) acuity 0.635. All eyes had significantly impaired visual fields and patients reported hearing loss as part of this syndromic retinitis pigmentosa. Treatment using the protocols of the SCOTS study using BMSC provided by retrobulbar, subtenons, intravitreal and intravenous injections.

Results

Following treatment, 80% of the Usher eyes showed an improvement in visual acuity. Of the eyes that improved the average increase in visual acuity was 36.4% on LogMAR with improvements ranging from 23% to 94%. The average post-operative change in all treated eyes was a gain of 0.18 LogMAR and an increase in visual acuity of 28.3% on LogMAR. The results showed high statistical significance with P<0.001. Visual fields generally improved. No patient experienced a loss of vision. One patient underwent preoperative and 4-month post-operative audiometry testing which demonstrated improvement. The procedures were performed safely and without complications.

Conclusions

Findings confirm meaningful improvement in visual acuity is possible in Usher syndrome using BMSC protocols developed in the SCOTS study. Statistical significance and safety were established.