The brain is capable of plasticity, so that the structural and functional loss that are caused by cortical injury may recover. Neuroinflammatory response can greatly influence post-injury recovery by modulating synaptic plasticity. In our previous work, mesenchymal derived exosomes were found to promote functional recovery by converting microglia from a pro-inflammatory state to an anti-inflammatory state in aged rhesus monkeys after cortical injury in the primary motor cortex. In the present project, we demonstrated the effects of exosomes on synaptic changes and synapse-microglia interactions after lesion in the same monkeys. To further investigate the effects of modulating neuroinflammation on synaptic changes after injury, we also investigated dietary curcumin, an anti-inflammatory substance, in a separate group of monkeys. Both treatments showed an effect as neuroinflammatory modulators that reduced the density of microglial markers, Iba- 1/P2RY12. However, the cortical injury induced synaptic loss was reversed by the exosome treatment, whereas the other anti-inflammatory treatment, curcumin, did not show the same effect. Our results are consistent with previous study that cortical injury induced synaptic loss and microglia activation. Exosomes can both reduce inflammation and synapse loss after injury, but curcumin only showed anti-inflammatory effects. Overall, these data suggested that exosomes and curcumin had different mechanisms of how to modulate inflammation and synaptic properties to promote recovery after cortical injury.

No description available.

abstract: Extracellular Vesicles (EVs), particularly exosomes, are of considerable interest as tumor biomarkers since tumor-derived EVs contain a broad array of information about tumor pathophysiology including its metabolic and metastatic status. However, current EV based assays cannot distinguish between EV biomarker changes by altered secretion of EVs during diseased conditions like cancer, inflammation, etc. that express a constant level of a given biomarker, stable secretion of EVs with altered biomarker expression, or a combination of these two factors. This issue was addressed by developing a nanoparticle and dye-based fluorescent immunoassay that can distinguish among these possibilities by normalizing EV biomarker level(s) to EV abundance, revealing average expression levels of EV biomarker under observation. In this approach, EVs are captured from complex samples (e.g. serum), stained with a lipophilic dye and hybridized with antibody-conjugated quantum dot probes for specific EV surface biomarkers. EV dye signal is used to quantify EV abundance and normalize EV surface biomarker expression levels. EVs from malignant (PANC-1) and nonmalignant pancreatic cell lines (HPNE) exhibited similar staining, and probe-to-dye ratios did not change with EV abundance, allowing direct analysis of normalized EV biomarker expression without a separate EV quantification step. This EV biomarker normalization approach markedly improved the ability of serum levels of two pancreatic cancer biomarkers, EV EpCAM, and EV EphA2, to discriminate pancreatic cancer patients from nonmalignant control subjects. The streamlined workflow and robust results of this assay are suitable for rapid translation to clinical applications and its flexible design permits it to be rapidly adapted to quantitate other EV biomarkers by the simple swapping of the antibody-conjugated quantum dot probes for those that recognize a different disease-specific EV biomarker utilizing a workflow that is suitable for rapid clinical translation. / Dissertation/Thesis / Doctoral Dissertation Biomedical Engineering 2019

Myocardial infarction (MI) frequently occurs in patients with diabetes resulting in higher mortality and morbidity than non-diabetic patients. We and others have shown that bone marrow-derived endothelial progenitor cells (BM-EPCs) promote cardiac neovascularization and attenuate ischemic injury in animal models. Lately, emerging evidence supports that exosomes (Exo), a family of extracellular vesicles, mediate stem cell therapy by carrying cell-specific biological cargo and by inducing signaling via transferring of bioactive molecules to target cells. Despite promising results of stem cells/Exo in preclinical studies, autologous cell-based therapies yielded modest clinical results, suggesting cellular/Exo reparative function may be compromised by the presence of comorbid diseases including complications associated with diabetes. Recent studies suggest that epigenetic mechanisms, such as histone and DNA modifications for gene silencing, promote diabetes-induced vascular complication. Therefore, we hypothesized that diabetic EPCs produce exosomes of altered and dysfunctional content that compromise their reparative function in ischemic heart disease via epigenetic alterations. We collected EPC-Exo from non-diabetic (db/+) and diabetic (db/db) mice and examined their reparative effect in vitro and on permanent left anterior descending (LAD) coronary artery ligation and ischemia/reperfusion (I/R) myocardial ischemic injuries in vivo. Our data demonstrated that compared to non-diabetic EPC-Exo, diabetic EPC-Exo promoted neonatal rat cardiomyocyte cell apoptosis under hypoxic stress and repressed endothelial tube formation and cell survival. In vivo studies revealed that non-diabetic EPC-Exo treatments improved cardiac function and remodeling while diabetic EPC-Exo significantly depressed cardiac function, reduced capillary density, increased fibrosis in the permanent LAD ligation MI injury. Moreover, in the I/R MI model, we found that non-diabetic EPC-Exo mediated cardio-protection was lost compared with diabetic-EPC-Exo, and diabetic-EPC-Exo increased immune cell infiltration, infarcted area, and plasma cardiac troponin-I. Mechanistically, histone 3 lysine 9 acetylation (H3K9Ac), a gene activating histone modification, expression was decreased in mouse cardiac endothelial cells (MCECs) treated with db/db EPC-Exo compared with db/+ EPC-Exo, suggesting diabetic EPC-Exo inhibits endothelial cell gene expression. The H3K9Ac chromatin immunoprecipitation sequencing (ChIP-Seq) results further revealed that diabetic EPC-Exo reduced H3K9Ac level on angiogenic, cell survival, and proliferative genes in MCECs. Moreover, we found that a small molecular inhibitor of HDACs, valproic acid (VPA), effectively prevented diabetic EPC-Exo-medicated H3K9Ac reduction, indicating VPA may rescue the beneficial gene expression and cell function. Taken together, our results provide evidence that diabetic EPC-Exo reparative function is impaired in the ischemic heart and this may be through HDACs-mediated H3K9Ac downregulation leading to inhibition of beneficial genes in recipient cardiac endothelial cells. Reversing diabetic EPC-Exo function by treating with HDAC inhibitors may provide a new path for autologous exosome therapy for myocardial repair in diabetic patients. However, questions still remain on what the content change of stem cell-derived exosome under diabetic condition is.Emerging evidence support a key role of variety of stem /progenitor cell-secreted Exo as a pivotal paracrine entity to mitigate cardiovascular injury. Beside EPC-, cortical bone stem cell (CBSC)-, and cardiac stem/progenitor cell (CPC)- derived Exo are adequate to enhance cardiac repair and regeneration after injury. As widely acknowledged, the comorbidities such as hyperglycemia is a characteristic of diabetes and a major driving factor in CVD. The functional role of stem/progenitor cell- derived Exo and molecular signature of their secreted Exo cargo under hyperglycemic conditions remain elusive. Therefore, we hypothesize that hyperglycemic stress causes transcriptome changes in stem/progenitor cell- derived Exo that may compromise their reparative function. To identify the content change in Exo under hyperglycemia, we performed an unbiased Exo transcriptome signatures from 3 different aforementioned stem/progenitor cells by next generation exosome RNA sequencing (RNA-seq). The results indicated that the size and number of Exo were not changed from 3 stem/progenitor cells between normal and high glucose groups. Furthermore, analysis revealed differential expression of variety of RNA species in Exo and the portions of different RNA were change under hyperglycemia. Specifically, we identified 241 common-dysregulated mRNAs, 21 ncRNAs and 16 miRNAs in three stem cell-derived Exo. Based on mRNA data, Gene Ontology (GO) revealed that potential function of common mRNAs mostly involved in metabolism and transcriptional regulation. We also provided the detail information of these non-annotated ncRNAs and the potential mRNA targets by miRNA-mRNA prediction. This study not only provides potential candidates for individual stem cell types but also identifies common genes in response to hyperglycemia. These reference data are critical for future biological studies and application of stem/progenitor cell-derived Exo in ischemic heart or other diseases to prevent the adverse effects of hyperglycemia-induced stem/progenitor cell- derived Exo dysfunction. / Biomedical Sciences / Accompanied by five Microsoft Excel files: 1) Supplementary Table 1 2) Supplementary Table 2 3) Supplementary Table 3 4) Supplementary Table 4 5) Supplementary Table 5

Almost half of patients recovering from open chest surgery experience atrial fibrillation (AF) that results principally from inflammation in the pericardial space surrounding the heart. Given that post-operative AF is associated with increased mortality, effective measures to prevent AF after open-chest surgery are highly desirable. In this study, we tested the concept that extracellular vesicles (EVs) isolated from human atrial explant-derived cells can prevent post-operative AF. Middle-aged female and male rats were randomized to undergo sham operation or induction of sterile pericarditis followed by trans-epicardial injection of human EVs or vehicle into the atrial tissue. Pericarditis increased the probability of inducing AF while EV treatment abrogated this effect in a sex independent manner. EV treatment reduced infiltration of inflammatory cells and production of pro-inflammatory cytokines. Atrial fibrosis and hypertrophy seen after pericarditis was markedly attenuated by EV pre-treatment; an effect attributable to suppression of fibroblast proliferation by EVs. Our study demonstrates that injection of extracellular vesicles at the time of open-chest surgery shows prominent anti-inflammatory effects and prevents AF due to sterile pericarditis. Translation of this finding to patients might provide an effective new strategy to prevent post-operative AF by reducing atrial inflammation and fibrosis.

Plusieurs aspects de la réponse immunitaire sont dérégulés de manière irréversible au cours de la phase aiguë de l'infection par le virus de l’immunodéficience de type 1 (VIH-1) menant à une activation immunitaire élevée et une inflammation généralisée impliquées dans l’épuisement du système immunitaire et la progression de la maladie. Nos travaux précédents ont mis en évidence une production plus élevée de vésicules extracellulaires (VE) appelées exosomes par les cellules dendritiques (CD) exposées au VIH-1. Ces exosomes ayant un effet pro-apoptotique sur les lymphocytes T CD4 (LT CD4), ils peuvent ainsi accentuer la déplétion de ces cellules, déjà initiée par l’infection elle-même. Produites par une grande variété de cellules et libérées dans de nombreux fluides corporels, les VE sont le reflet de leur cellule d’origine et peuvent transporter des protéines mais aussi du matériel génétique (ARN, microARN) aux cellules voisines faisant d’elles des messagers essentiels à la communication intercellulaire. De par leur contenu, les VE sont impliquées dans différents processus biologiques dont la modulation de la réponse immunitaire. En s’appuyant sur ces données et sur l’implication des microARN dans la modulation des réponses immunitaires, l’hypothèse du rôle des VE dans la mise en place et l’entretien des perturbations immunitaires associée à la pathogenèse au VIH-1, notamment via leur contenu en microARN, a émergé. Mes travaux de doctorat ont montré un profil en VE plasmatiques spécifique associé au statut clinique des sujets infectés par le VIH-1. La quantité et la taille des VE retrouvées dans le plasma de sujets infectés non traités sont plus élevées que chez les individus contrôles et corrèlent avec la déplétion en LT CD4 ou la baisse du ratio CD4/CD8, considérés comme des marqueurs de l’évolution de la maladie, soulignant le potentiel biomarqueur des VE dans la progression de l’infection. De plus, ces données révèlent un enrichissement des VE en microARN, dont le miR-155, auparavant décrit dans la modulation de différentes réponses immunitaires. L’inoculation subséquente d’une production virale enrichie en VE miR-155-positives dans un modèle de souris humanisées a mis en évidence la contribution du miR-155 vésiculaire dans le développement des perturbations immunitaires et la progression de la pathogenèse associée à l’infection par le VIH-1. Ainsi, une meilleure compréhension des mécanismes participant à l’enrichissement du miR-155 dans les VE permettrait éventuellement un contrôle de l’épuisement immunitaire caractéristique de l’infection par le VIH-1 et, à plus long terme, ouvrirait de nouvelles perspectives pour le développement de thérapies. / Several aspects of the immune response are irreversibly dysregulated during the acute phase of HIV-1 infection leading to a generalized immune activation and inflammation which are involved in immune cells depletion and disease progression. Our previous work revealed a higher production of extracellular vesicles (EVs) called exosomes by HIV-1 pulsed dendritic cells (DCs). These exosomes displayed pro-apoptotic effect on CD4 T lymphocytes (CD4 TL), and thus increase the depletion of these cells, already initiated by the infection itself. Produced by a wide variety of cells and released into body fluids, EVs, which reflect cellular origin, are believed to function as messengers in intercellular communication delivering proteins and genetic material (RNA, microRNA) to neighboring cells. By their content, EVs are involved in various biological processes including the modulation of immune responses. Based on these data and the involvement of microRNAs in immune response modulation, the hypothesis assuming the role of EVs in the establishment and maintenance of immune disruptions during HIV-1 pathogenesis, notably through their microRNA content, has emerged. My doctoral research showed a specific profile of plasma EVs associated with clinical status of HIV-1 infected patients. The amount and size of EVs present in the plasma of HIV-1- infected patients’ naïve for treatment were higher than those from healthy individuals and correlate with CD4 TL depletion or CD4/CD8 ratio decrease, which are considered markers of disease progression. These data highlight the biomarker potential of EVs. Furthermore, microRNAs are enriched in EVs, including miR-155, previously described in different immune responses. Subsequent inoculation of EV-borne miR-155-enriched-virus in a humanized mouse model revealed that vesicular miR-155 can contribute to the development of immune disruptions and the progression of HIV-1-associated pathogenesis. To conclude, a greater understanding of the mechanisms involved in miR-155 enrichment in EVs would help to control the immune exhaustion characteristic of HIV-1 infection and, on long-term, would open new perspectives for therapies.

Natural Killer (NK) cell based immunotherapies have demonstrated success against malignancies and hematological cancers. However, tumors have developed mechanisms to evade detection by and suppress the immune system, commonly through altering the expression of cell-surface proteins. Overexpression of human leukocyte antigen-E (HLA-E), which binds to the inhibitory NKG2A on NK cells, protects malignant cells from lysis. Downregulating the NKG2A receptor on NK cells should release NK cell inhibition, but proves challenging as NK cells are difficult to transfect and no good methods currently exist. This project is designed to investigate the use of exosomes – small vesicles and natural carriers of regulatory microRNAs (miRNAs) and proteins that are shed from cells – as delivery vehicles for small RNAs (sRNAs) to immune cells. Exosomes are biologically compatible, immunologically inert, and interact with target cells through receptor-ligand interactions, allowing for targeted delivery of cargo. Exosomes loaded with shRNA against NKG2A were cultured in vitro with NK cells. Delivery success was assessed by monitoring NKG2A receptor expression on NK cells through flow cytometry. This research will provide valuable information that will likely impact the delivery of RNA therapeutics and unlock the full cytotoxic potential of NK immunotherapy.

No description available.

No description available.

L’infection par le virus de l'immunodéficience humaine de type 1 (VIH-1) entraîne le dysfonctionnement du système immunitaire menant à la déplétion de lymphocytes TCD4 (LTCD4) dans les tissus lymphoïdes. Cette diminution cellulaire est causée par la lyse cellulaire virale, par la cytotoxicité dépendante des lymphocytes TCD8 (LTCD8), par l’apoptose des LTCD4 bystanders et par un effet cytopathique des facteurs solubles libérés pendant l’infection. Les exosomes, des vésicules (30-100 nm) d’origine endosomale, ont également été impliqués dans la déplétion des cellules bystanders. En effet, ils portent des molécules participant à la mort cellulaire (Nef, Apaf-1, Dap-3) dérivées de cellules infectées par le VIH-1. Les exosomes et les particules de VIH-1 ont plusieurs similitudes de forme, de composition protéique et lipidique, ainsi que de contenu en acide nucléique. La biogenèse des exosomes converge avec le bourgeonnement des particules virales dans les endosomes de cellules dendritiques (CDs). De même, ces vésicules sont libérées conjointement avec les particules virales vers les LTCD4. Le DCIR (dendritic cell immunoreceptor), une lectine membranaire de type C, agit comme un facteur d’attachement et d’internalisation du VIH-1. Le DCIR augmente donc la production virale sur les LTCD4 et les CDs. Nous avons montré précédemment que l’infection virale des CDs favorise la libération des exosomes dans le milieu extracellulaire. Par ce travail, nous avons montré que le DCIR et ses voies de signalisation étaient impliqués dans la libération ou l’accumulation des exosomes dans les milieux extracellulaires après le contact avec le VIH-1. Nous avons aussi observé que l’inhibition extracellulaire du DCIR sur les CDs a affecté la sécrétion des exosomes induite par le VIH-1. Enfin, nos résultats ont également affirmé que les exosomes dérivés de cellules infectées par le VIH-1 induisaient l’apoptose des LTCD4 Th17, alors qu’ils protègent les neutrophiles. L’ensemble des résultats nous permet d’améliorer la compréhension de la pathogenèse du VIH-1 en mettant en évidence le rôle que joue le DCIR dans la sécrétion des exosomes.