Exosomal miR-146a Research Articles

Exosomes derived from oxLDL-stimulated macrophages induce neutrophil extracellular traps to drive atherosclerosis

ABSTRACT This study aimed to investigate the role and underlying mechanism of exosomes secreted by oxidized low-density lipoprotein (oxLDL)-stimulated macrophages in the progression of atherosclerosis (AS). Exosomes from peripheral blood of AS patients or oxLDL-treated macrophages were co-cultured with human neutrophils. Neutrophil extracellular traps (NETs) were detected by immunofluorescence staining. The levels of inflammatory cytokines were quantified by enzyme-linked immunosorbent assay (ELISA). The expression levels of miR-146a and superoxide dismutase 2 (SOD2) were determined by quantitative real-time PCR (qRT-PCR) and western blot. The generation of intracellular reactive oxygen species (ROS) was observed by using dichlorofluorescin diacetate (DCFH-DA). ApoE-deficient mice were fed with high-fat diet (HFD) to induce AS. Atherosclerotic plaques were evaluated by Oil red O (ORO) and hematoxylin-eosin (HE) staining. Our results showed that miRNA-146a was enriched in serum-derived exosomes of AS patients and oxLDL-treated macrophage THP-1-derived exosomes. Importantly, exosomal miR-146a secreted by oxLDL-treated macrophages promoted ROS and NETs release via targeting SOD2. In addition, intravenous administration of oxLDL-treated THP-1 cells-derived exosomes into AS mice significantly deteriorated AS in vivo. Our findings indicate that exosomal miR-146a derived from oxLDL-treated macrophages promotes NETs formation via inducing oxidative stress, which might provide a novel scientific basis for the understanding of AS progression.

MiR-146a is a negative regulator of IL-33-stimulated mouse mast cells

Abstract Interleukin-33 (IL-33) is an inflammatory cytokine that promotes allergic disease by activating ILC2, Th2, and mast cells. IL-33 is increased in asthmatics, and its blockade suppresses asthma-like inflammation in mouse models. The IL-33 receptor, ST2, shares signaling cascades with the TLR family, but homeostatic control of ST2 function is poorly understood. MicroRNA-146a (miR-146a) is induced by LPS and suppresses TLR4 signaling in macrophages. Therefore, we explored whether miR-146a has a role in IL-33 signaling. IL-33 induced cellular and exosomal miR-146a expression in mouse bone marrow derived mast cells (BMMC). Induction required MyD88, Akt, and NFkB, since antagonizing these pathways decreased miR-146 expression. BMMC transfected with a miR-146a antagomir or derived from miR-146a KO mice showed enhanced cytokine expression in response to IL-33, suggesting that miR-146a is a negative regulator of IL-33-ST2 signaling. Our data further suggest that miR-146a may act by targeting IRAK proteins, because mir-146a KO BMMC have increased TRAF6, IRAK1, and IRAK4 expression. In vivo, miR-146a expression in plasma exosomes was elevated after intraperitoneal injection of IL-33. Also mast cell deficient c-Kitw-sh mice acutely reconstituted with miR-146a KO BMMC intraperitoneally had elevated plasma IL-6 levels in comparison to their WT counterparts after IL-33 challenge. These results support the hypothesis that miR-146a is a feedback regulator of IL-33-mediated mast cell functions associated with allergic disease.

RAB27B-activated secretion of stem-like tumor exosomes delivers the biomarker microRNA-146a-5p, which promotes tumorigenesis and associates with an immunosuppressive tumor microenvironment in colorectal cancer.

The dynamic cell-cell communication is essential for tissue homeostasis in normal physiological circumstances and contributes to a diversified tumor microenvironment. Although exosomes are extracellular vesicles that actively participate in cell-cell interaction by shutting cellular components, impacts of tumor exosomes in the context of cancer stemness remain elusive. Here, we expand colorectal cancer stem cells (CRCSCs) as cancer spheroids and demonstrate that the β-catenin/Tcf-4-activated RAB27B expression is required for the secretion of CRCSC exosomes. In an exosomal RNA sequencing analysis, a switch of exosomal RNA species from retrotransposons to microRNAs (miRNAs) is identified upon expanding CRCSCs. miRNA-146a-5p (miR-146a) is the major miRNA in CRCSC exosomes and exosomal miR-146a promotes stem-like properties and tumorigenicity by targeting Numb in recipient CRC cells. Among 53 CRC patients, those with abundant exosomal miR-146a expression in serum exhibits higher miR-146aHigh /NumbLow CRCSC traits, an increased number of tumor-filtrating CD66(+) neutrophils and a decreased number of tumor-infiltrating CD8(+) T cells. Our study elucidates a unique mechanism of tumor exosome-mediated stemness expansion.

Altered Expression of miR-326 in T Cell-derived Exosomes of Patients with Relapsing-remitting Multiple Sclerosis

Invasion of auto-reactive CD4+ T cells especially Th17 into central nervous system (CNS) is an underlying pathogenic mechanism in multiple sclerosis (MS). CD4+ T cells release exosomes which are enriched in microRNAs, reflective of cell's physiological or pathological condition. Thus exosomes could be potent agents to provide quantitative and qualitative information about involved cells in MS. We investigated the expression of pathogenic microRNAs in T cells-derived exosomes of MS patients or healthy controls. Conventional T cells (Tconv) derived from relapsing-remitting (RR) MS patients (n=10) and healthy controls (n=10) were purified and cultured for 3 days by soluble anti-CD3/CD28. Exosomes were purified from cultured-T cells supernatants. The expression levels of exosomal miR-146a, miR-29a, miR-155, and miR-326 were quantified by real-time PCR. A statistically significant increased expression of miR-326 in Tconv-derived exosomes was observed in RRMS patients as compared with controls (7.5±1.88vs 2.51±0.9 p=0.03), On the contrary, no differences were found in the expression levels of miR-155, miR-146a, and miR-29a, in Tconv-derived exosomes of patients as compared with controls (p>0.05).Our results point to altered expression in exosome-derived microRNAs. MiR-326 was previously shown to play a role in the immunopathogenesis of MS by inducing TH17 differentiation and maturation. Therefore, miR-326 containing exosomes might also be a potential clinical target in course of MS. Moreover, the deregulation of this miRNA in exosomes may serve as a diagnostic and prognostic biomarker.

The expression level of hsa-miR-146a-5p in plasma-derived exosomes of patients with diffuse large B-cell lymphoma.

Background:The standard treatment for patients with diffuse large B-cell lymphoma (DLBCL) had been rituximab-based immunochemotherapy. However, the biological and clinical heterogeneity within DLBCL seems to affect treatment outcome. Therefore, the evaluation of miRNA levels might be useful in predicting treatment response and relapse risk. miR-146a is a modulator of innate and acquired immunity and may play an important role in predicting treatment response. The aim of the present study was to compare the expression level of miR-146a in plasma-derived exosomes of responsive DLBCL patients (response to R-CHOP (Rituximab, and Cyclophosphamide, Hydroxydaunorubicin, Oncovine and Prednisone)), refractory DLBCL patients (resistant to R-CHOP), patients receiving R-CHOP, and healthy donors.Materials and Methods:After the preparation of plasma and isolation of exosomes, the presence of plasma-derived exosome was confirmed by Zetaseizer, electron microscope, and Western blot. The patients’ medical records were collected and analyzed. The expression level of exosomal miR-146a was evaluated in DLBCL patients and healthy donors using real-time polymerase chain reaction (PCR). The −ΔCt values of miR-146a were compared among responsive patients (n = 17), refractory patients (n = 16), patients receiving R-CHOP therapy (n = 15), and healthy donors (n = 6).Results:The presence and size of plasma-derived exosomes were confirmed. Our findings did not show any significant difference in the expression level of exosomal miR-146a between DLBCL patients and healthy donors (P = 0.48). As well, the clinical and histopathological parameters were not correlated with the expression level of exosomal miR-146a or plasma miR-146a. The expression level of plasma miR-146 was lower than the expression level of exosomal miR-146 (P = 0.01).Conclusion:Exosomal miR-146a might be useful as a promising “liquid biopsy” biomarker in predicting treatment response and relapse risk; however, we could not find significant differences due to small sample size.

An enriched environment prevents diabetes-induced cognitive impairment in rats by enhancing exosomal miR-146a secretion from endogenous bone marrow-derived mesenchymal stem cells.

Increasing evidence suggests that an enriched environment (EE) ameliorates cognitive impairment by promoting repair of brain damage. However, the mechanisms by which this occurs have not been determined. To address this issue, we investigated whether an EE enhanced the capability of endogenous bone marrow-derived mesenchymal stem/stromal cells (BM-MSCs) to prevent hippocampal damage due to diabetes by focusing on miRNA carried in BM-MSC-derived exosomes. In diabetic streptozotocin (STZ) rats housed in an EE (STZ/EE), cognitive impairment was significantly reduced, and both neuronal and astroglial damage in the hippocampus was alleviated compared with STZ rats housed in conventional cages (STZ/CC). BM-MSCs isolated from STZ/CC rats had functional and morphological abnormalities that were not detected in STZ/EE BM-MSCs. The miR-146a levels in exosomes in conditioned medium of cultured BM-MSCs and serum from STZ/CC rats were decreased compared with non-diabetic rats, and the level was restored in STZ/EE rats. Thus, the data suggest that increased levels of miR-146a in sera were derived from endogenous BM-MSCs in STZ/EE rats. To examine the possibility that increased miR-146a in serum may exert anti-inflammatory effects on astrocytes in diabetic rats, astrocytes transfected with miR-146a were stimulated with advanced glycation end products (AGEs) to mimic diabetic conditions. The expression of IRAK1, NF-κB, and tumor necrosis factor-α was significantly higher in AGE-stimulated astrocytes, and these factors were decreased in miR-146a-transfected astrocytes. These results suggested that EEs stimulate up-regulation of exosomal miR-146a secretion by endogenous BM-MSCs, which exerts anti-inflammatory effects on damaged astrocytes and prevents diabetes-induced cognitive impairment.

MicroRNA-146a is a negative regulator of IL-33 stimulated mouse mast cells.

Abstract Interleukin 33 (IL-33) is an inflammatory cytokine that promotes allergic disease by activating ILC2, Th2 cells, and mast cells. IL-33 is increased in asthmatics, and its blockade suppresses asthma-like inflammation in mouse models. The IL-33 receptor, ST2, shares signaling cascades with the TLR family, but homeostatic control of ST2 function is poorly understood. MicroRNA-146a (miR-146a) is induced by LPS and suppresses TLR4 signaling in macrophages. Therefore, we explored whether miR-146a has a role in IL-33 signaling. IL-33 induced cellular and exosomal miR-146a expression in mouse bone marrow derived mast cells (BMMC). Induction required MyD88, Akt, and NFκB, since antagonizing these pathways decreased miR-146 expression. BMMC transfected with a miR-146a antagomir or derived from miR-146a KO mice showed enhanced cytokine expression in response to IL-33, suggesting that mir46a is a negative regulator of IL-33-ST2 signaling. Our data further suggest that miR-146a may act by targeting IRAK proteins, because mir146a KO BMMC have increased IRAK1 and IRAK4 expression. These results support the hypothesis that miR-146a is a feedback regulator of IL-33-mediated mast cell functions associated with allergic disease.

MP58-08 CANCER-ASSOCIATED FIBROBLASTS SECRETED EXOSOMAL MIR-146A PROMOTES BLADDER CANCER CHEMORESISTANCE

You have accessJournal of UrologyBladder Cancer: Basic Research & Pathophysiology II1 Apr 2018MP58-08 CANCER-ASSOCIATED FIBROBLASTS SECRETED EXOSOMAL MIR-146A PROMOTES BLADDER CANCER CHEMORESISTANCE Junlong Zhuang, Lan Shen, Jun Yan, and Hongqian Guo Junlong ZhuangJunlong Zhuang More articles by this author , Lan ShenLan Shen More articles by this author , Jun YanJun Yan More articles by this author , and Hongqian GuoHongqian Guo More articles by this author View All Author Informationhttps://doi.org/10.1016/j.juro.2018.02.1840AboutPDF ToolsAdd to favoritesDownload CitationsTrack CitationsPermissionsReprints ShareFacebookTwitterLinked InEmail INTRODUCTION AND OBJECTIVES Urinary bladder cancer (UBC) patients at muscle invasive stage have poor clinical outcome, due to high propensity for chemoresistance. Cancer-associated fibroblasts (CAFs), one of the principal constituents of the tumor stroma, play an important role in tumor development. Exosomal microRNAs (miRNAs) are emerging mediators of cancer-host crosstalk with other cells around. However, it is unclear whether CAFs from UBC promote cancer chemoresistance through exosomal miRNAs. METHODS We obtained human bladder cancer specimens and adjacent normal tissues from Nanjing Drum Tower Hospital. The bladder cancer specimen used for isolation of stromal fibroblasts was diagnosed as muscle invasive bladder cancer with histological grade II. Bladder cancer cells (T24 and 5637) were treated with the conditional medium (CM) or exosomes from normal fibroblasts (NFs) and CAFs, as well as an equal volume of complete culture medium. Exosomes were isolated from NF-CM or CAF-CM using ultracentrifugation or Total Exosome Isolation kit. T24 cells and NFs or CAFs in 0.1 ml 50% Matrigel were injected subcutaneously into the right flank of male athymic nude mice. Gemcitabine (40 mg/kg body weight) and cisplatin (6 mg/kg body weight) were respectively given on day 1, 5, 8 ,11 and day 2 via intraperitoneal injection. Tumor diameters were measured with calipers every 3 days and tumor volumes were calculated. The log-rank t-test was used for survival analysis. P value less than 0.05 was considered statistically significant. RESULTS We found that co-culture with UBC CAFs promoted T24 xenograft tumor stemness in vivo. Compared to NFs, CAF cells promotes bladder cancer cell stemness via secreted exosomes in vitro. We conducted microarray assay to identify exosomal miRNAs potentially secreted by UBC CAFs and found that miR-146a was the most highly expressed and secreted. Mimic miR-146a also enhanced the stemness of UBC cells. To further confirm the effect of miR-146a on crosstalk between CAFs and UBC in vivo, we stably overexpressed miR-146a or control vector in NFs (NF/miR-146a and NF/vec) and co-cultured with T24 cells, respectively. CAF or NF/miR-146a significantly enhanced T24 xenograft tumor stemness and chemoresistance. Bioinformatic analyses found that AMPKα contain potential miR-146a binding sites in its 3′-UTRs. We further comfirmed that exosomal miR-146a repress AMPKα to induce mTOR signal pathway. Consistently, serum exosomal miR-146a expression is positively correlated with recurrence, and patients with high miR-146a had a poor prognosis. CONCLUSIONS CAF cells promotes bladder cancer cell stemness via secreted exosomes. CAFs-secreted exosomal miR-146a promotes bladder cancer chemoresistance through the AMPK/mTOR pathway. Exosomal miR-146a may serve as a predictor and a potential therapeutic target for bladder cancer recurrence. © 2018FiguresReferencesRelatedDetails Volume 199Issue 4SApril 2018Page: e775-e776 Advertisement Copyright & Permissions© 2018MetricsAuthor Information Junlong Zhuang More articles by this author Lan Shen More articles by this author Jun Yan More articles by this author Hongqian Guo More articles by this author Expand All Advertisement Advertisement PDF downloadLoading ...

Exosome-mediated miR-146a transfer suppresses type I interferon response and facilitates EV71 infection.

Exosomes can transfer genetic materials between cells. Their roles in viral infections are beginning to be appreciated. Researches have shown that exosomes released from virus-infected cells contain a variety of viral and host cellular factors that are able to modulate recipient’s cellular response and result in productive infection of the recipient host. Here, we showed that EV71 infection resulted in upregulated exosome secretion and differential packaging of the viral genomic RNA and miR-146a into exosomes. We provided evidence showing that miR-146a was preferentially enriched in exosomes while the viral RNA was not in infected cells. Moreover, the exosomes contained replication-competent EV71 RNA in complex with miR-146a, Ago2, and GW182 and could mediate EV71 transmission independent of virus-specific receptor. The exosomal viral RNA could be transferred to and replicate in a new target cell while the exosomal miR-146a suppressed type I interferon response in the target cell, thus facilitating the viral replication. Additionally, we found that the IFN-stimulated gene factors (ISGs), BST-2/tetherin, were involved in regulating EV71-induced upregulation of exosome secretion. Importantly, in vivo study showed that exosomal viral RNA exhibited differential tissue accumulation as compared to the free virus particles. Together, our findings provide evidence that exosomes secreted by EV71-infected cells selectively packaged high level miR-146a that can be functionally transferred to and facilitate exosomal EV71 RNA to replicate in the recipient cells by suppressing type I interferon response.

520 - Cancer-associated fibroblasts secreted exosomal miR-146a promotes bladder cancer progression

520 - Cancer-associated fibroblasts secreted exosomal miR-146a promotes bladder cancer progression

Exosomal miR-146a Contributes to the Enhanced Therapeutic Efficacy of Interleukin-1β-Primed Mesenchymal Stem Cells Against Sepsis.

Improving the immunomodulatory efficacy of mesenchymal stem cells (MSCs) through pretreatment with pro-inflammatory cytokines is an evolving field of investigation. However, the underlying mechanisms have not been fully clarified. Here, we pretreated human umbilical cord-derived MSCs with interleukin-1β (IL-1β) and evaluated their therapeutic effects in a cecal ligation and puncture-induced sepsis model. We found that systemic administration of IL-1β-pretreated MSCs (βMSCs) ameliorated the symptoms of murine sepsis more effectively and increased the survival rate compared with naïve MSCs. Furthermore, βMSCs could more effectively induce macrophage polarization toward an anti-inflammatory M2 phenotype through the paracrine activity. Mechanistically, we demonstrated that βMSC-derived exosomes contributed to the enhanced immunomodulatory properties of βMSCs both in vitro and in vivo. Importantly, we found that miR-146a, a well-known anti-inflammatory microRNA, was strongly upregulated by IL-1β stimulation and selectively packaged into exosomes. This exosomal miR-146a was transferred to macrophages, resulted in M2 polarization, and finally led to increased survival in septic mice. In contrast, inhibition of miR-146a through transfection with miR-146a inhibitors partially negated the immunomodulatory properties of βMSC-derived exosomes. Taken together, IL-1β pretreatment effectively enhanced the immunomodulatory properties of MSCs partially through exosome-mediated transfer of miR-146a. Therefore, we believe that IL-1β pretreatment may provide a new modality for better therapeutic application of MSCs in inflammatory disorders. Stem Cells 2017;35:1208-1221.

Exosome-delivered microRNAs modulate the inflammatory response to endotoxin.

MicroRNAs regulate gene expression posttranscriptionally and function within the cells in which they are transcribed. However, recent evidence suggests that microRNAs can be transferred between cells and mediate target gene repression. We find that endogenous miR-155 and miR-146a, two critical microRNAs that regulate inflammation, are released from dendritic cells within exosomes and are subsequently taken up by recipient dendritic cells. Following uptake, exogenous microRNAs mediate target gene repression and can reprogramme the cellular response to endotoxin, where exosome-delivered miR-155 enhances while miR-146a reduces inflammatory gene expression. We also find that miR-155 and miR-146a are present in exosomes and pass between immune cells in vivo, as well as demonstrate that exosomal miR-146a inhibits while miR-155 promotes endotoxin-induced inflammation in mice. Together, our findings provide strong evidence that endogenous microRNAs undergo a functional transfer between immune cells and constitute a mechanism of regulating the inflammatory response.

Secretory Mechanisms and Intercellular Transfer of MicroRNAs in Living Cells

The existence of circulating microRNAs (miRNAs) in the blood of cancer patients has raised the possibility that miRNAs may serve as a novel diagnostic marker. However, the secretory mechanism and biological function of extracellular miRNAs remain unclear. Here, we show that miRNAs are released through a ceramide-dependent secretory machinery and that the secretory miRNAs are transferable and functional in the recipient cells. Ceramide, whose biosynthesis is regulated by neutral sphingomyelinase 2 (nSMase2), triggers secretion of small membrane vesicles called exosomes. The decreased activity of nSMase2 with a chemical inhibitor, GW4869, and a specific small interfering RNA resulted in the reduced secretion of miRNAs. Complementarily, overexpression of nSMase2 increased extracellular amounts of miRNAs. We also revealed that the endosomal sorting complex required for transport system is unnecessary for the release of miRNAs. Furthermore, a tumor-suppressive miRNA secreted via this pathway was transported between cells and exerted gene silencing in the recipient cells, thereby leading to cell growth inhibition. Our findings shed a ray of light on the physiological relevance of secretory miRNAs.