Extracellular Vesicles and Immune System in Ageing and Immune Diseases

Immune system is essential for host homeostasis. Immune cells communicate with each other by binding to receptors or by releasing vesicles including chemokines and cytokines. Under healthy circumstances, immune cell-derived factors are critical for cellular growth, division and function, whereas under conditions such as ageing and inflammatory states, they can aggravate pathologies and cause disease. Cell-derived membranous extracellular vesicles mediate cell-to-cell communication and are implicated in various physiological and pathological processes involving ageing and age-related diseases. Extracellular vesicles are responsible for spreading detrimental factors to the surroundings and the propagation phase of inflammatory diseases. The regulation of extracellular vesicles is a putative target for treatment of inflammatory diseases. Moreover, their features are ideal for developing biomarkers and drug delivery systems modulated by bioengineering in inflammatory diseases. The present review summarizes the current understanding of extracellular vesicles in ageing and inflammatory diseases.ope

Extracellular Vesicles and Damage-Associated Molecular Patterns: A Pandora\u2019s Box in Health and Disease

Sterile inflammation develops as part of an innate immunity response to molecules released upon tissue injury and collectively indicated as damage-associated molecular patterns (DAMPs). While coordinating the clearance of potential harmful stimuli, promotion of tissue repair, and restoration of tissue homeostasis, a hyper-activation of such an inflammatory response may be detrimental. The complex regulatory pathways modulating DAMPs generation and trafficking are actively investigated for their potential to provide relevant insights into physiological and pathological conditions. Abnormal circulating extracellular vesicles (EVs) stemming from altered endosomal-lysosomal system have also been reported in several age-related conditions, including cancer and neurodegeneration, and indicated as a promising route for therapeutic purposes. Along this pathway, mitochondria may dispose altered components to preserve organelle homeostasis. However, whether a common thread exists between DAMPs and EVs generation is yet to be clarified. A deeper understanding of the highly complex, dynamic, and variable intracellular and extracellular trafficking of DAMPs and EVs, including those of mitochondrial origin, is needed to unveil relevant pathogenic pathways and novel targets for drug development. Herein, we describe the mechanisms of generation of EVs and mitochondrial-derived vesicles along the endocytic pathway and discuss the involvement of the endosomal-lysosomal in cancer and neurodegeneration (i.e., Alzheimer\u2019s and Parkinson\u2019s disease)

Cell clearing systems as targets of polyphenols in viral infections: Potential implications for COVID-19 pathogenesis

The novel coronavirus named severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) has generated the ongoing coronavirus disease-2019 (COVID-19) pandemic, still with an uncertain outcome. Besides pneumonia and acute lung injury (ALI) or acute respiratory distress syndrome (ARDS), other features became evident in the context of COVID-19. These includes endothelial and coagulation dysfunction with disseminated intravascular coagulation (DIC), and multiple organ dysfunction syndrome (MODS), along with the occurrence of neurological alterations. The multi-system nature of such viral infection is a witness to the exploitation and impairment of ubiquitous subcellular and metabolic pathways for the sake of its life-cycle, ranging from host cell invasion, replication, transmission, up to a cytopathic effect and overt systemic inflammation. In this frame, alterations in cell-clearing systems of the host are emerging as a hallmark in the pathogenesis of various respiratory viruses, including SARS-CoV-2. Indeed, exploitation of the autophagy and proteasome pathways might contribute not only to the replication of the virus at the site of infection but also to the spreading of either mature virions or inflammatory mediators at both cellular and multisystem levels. In this frame, besides a pharmacological therapy, many researchers are wondering if some non-pharmacological substances might counteract or positively modulate the course of the infection. The pharmacological properties of natural compounds have gained increasing attention in the field of alternative and adjunct therapeutic approaches to several diseases. In particular, several naturally-occurring herbal compounds (mostly polyphenols) are reported to produce widespread antiviral, anti-inflammatory, and anti-oxidant effects while acting as autophagy and (immuno)-proteasome modulators. This article attempts to bridge the perturbation of autophagy and proteasome pathways with the potentially beneficial effects of specific phytochemicals and flavonoids in viral infections, with a focus on the multisystem SARS-CoV-2 infection

Spliceosome SNRNP200 promotes viral RNA sensing and IRF3 activation of antiviral response

Le système immunitaire innée est la première ligne de défense de l’organisme contre une multitude d’agents pathogènes tel que les bactéries, les virus, les parasites et les champignons. Afin d’identifier de nouveau régulateur de l’immunité antivirale innée, nous avons complété le premier criblage pangénomique par ARN interférent (RNAi) s’intéressant à la réponse transcriptionnelle de l’interféron-β (IFNB1) suite à une infection par le virus Sendai (SeV). De façon surprenante, une analyse d’enrichissement génomique (GESA) nous a permis d’identifier 114 gènes régulateurs dont plusieurs facteurs du splicéosome. Par eux, nous avons priorisé la caractérisation de SRNNP200, une protéine clé de la machinerie d’épissage des introns et une hélicase de la famille Ski2, sur la base de similitudes entre sa structure et celle d’autres hélicases antivirales tel que RIG-I et MDA5. Dans cette thèse, nous montrons, pour la première fois, un rôle distinct, pour SNRNP200, de sa fonction canonique dans l’épissage des pré-ARNs. En effet, le silençage de l’expression de SNRNP200 dans des lignées de cellules humaines primaires entraîne une réduction de l’immunité antivirale et une augmentation de la susceptibilité à une infection virale. Plus spécifiquement, nous montrons que SNRNP200 est un régulateur positif de l’activation de IRF3 via une interaction protéine-protéine avec la sérine/thréonine-kinase TBK1. Additionnement, nous avons montré que, lors d’une infection, SNRNP200 est capable de lier l’ARN viral cytoplasmique et qu’il relocalise, du noyau au cytoplasme, avec TBK1 dans des structures périnucléaires distinctes et spécifiques. En lien avec la clinique, nous avons observé une réponse antivirale réduite dans les cellules mononucléées du sang périphérique (PBMC) de patients atteints de rétinite pigmentaire de type 33 (RP33) causée par des mutations dans le gène SNRNP200. De plus, nous avons démontré qu’un mutant de SNRNP200 associé à RP33 n’était plus en mesure de lier l’ARN viral cytoplasmique ou de rétablir l’immunité antivirale de cellules ciblée par un RNAi lors d’une expérience de sauvetage. Ainsi, cette thèse présente les premiers travaux portant sur la fonction immunomodulatrice de SNRNP200 et de son rôle comme senseur d’ARN viral et de protéines adaptatrice de TBK1 et d’IRF3.The innate immune system is the first line of defense against invading pathogens of many kind such as bacteria, viruses, parasites and fungi. Its role is straightforward: it acts within minutes of a pathogenic engagement to control and restrict the microscopic invasion using non-specific mechanisms while the host mounts an induced, and specific, innate and adaptive response. To identify new regulators of antiviral innate immunity, we have completed the first genome-wide gene RNAi screen assessing the transcriptional response at the interferon-β (IFNB1) promoter following Sendai virus (SeV) infection. Interestingly, a Gene Set Enrichment Analysis (GSEA) of the 114 gene hits revealed that many of these proteins were spliceosome-associated. Among them, we further prioritized the characterization of SNRNP200, a core and unique spliceosomal member of the Ski2-like RNA helicase family based on its structural similarities to other antiviral RNA helicase like RIG-I and MDA5. In this thesis, we provide evidence for a role of the spliceosomal SNRNP200 that is clearly distinguishable of the one in pre-mRNA splicing. Indeed, the depletion of SNRNP200 in human cells resulted in a reduced antiviral response and increased susceptibility to viral infection. We specifically showed that SNRNP200 positively regulates activation of the key antiviral transcriptional factor IRF3 via a protein-protein interaction with the serine/threonine-protein kinase TBK1. Additionally, we showed that upon infection, SNRNP200 binds viral RNA and relocalizes into TBK1-containing cytoplasmic structures to promote innate signaling. Of clinical relevance, we observed a significantly hindered antiviral response of PBMCs from patients carrying a dominant SNRNP200 mutation associated to the retina pigmentosa type 33 (RP33), an inherited degenerative eye disease. We showed that expression of the RP33-associated mutant has lost the ability to bind RNA and to rescue antiviral response in SNRNP200 silenced cells. Thus, this thesis provides new insights into an immunoregulatory role of spliceosome SNRNP200 acting as an RNA sensor and adaptor of TBK1 to promote IRF3 signaling in antiviral response

Role of microRNAs in Alcohol-Induced Multi-Organ Injury

Alcohol consumption and its abuse is a major health problem resulting in significant healthcare cost in the United States. Chronic alcoholism results in damage to most of the vital organs in the human body. Among the alcohol-induced injuries, alcoholic liver disease is one of the most prevalent in the United States. Remarkably, ethanol alters expression of a wide variety of microRNAs that can regulate alcohol-induced complications or dysfunctions. In this review, we will discuss the role of microRNAs in alcoholic pancreatitis, alcohol-induced liver damage, intestinal epithelial barrier dysfunction, and brain damage including altered hippocampus structure and function, and neuronal loss, alcoholic cardiomyopathy, and muscle damage. Further, we have reviewed the role of altered microRNAs in the circulation, teratogenic effects of alcohol, and during maternal or paternal alcohol consumption

Role of microRNAs in Alcohol-Induced Multi-Organ Injury

Alcohol consumption and its abuse is a major health problem resulting in significant healthcare cost in the United States. Chronic alcoholism results in damage to most of the vital organs in the human body. Among the alcohol-induced injuries, alcoholic liver disease is one of the most prevalent in the United States. Remarkably, ethanol alters expression of a wide variety of microRNAs that can regulate alcohol-induced complications or dysfunctions. In this review, we will discuss the role of microRNAs in alcoholic pancreatitis, alcohol-induced liver damage, intestinal epithelial barrier dysfunction, and brain damage including altered hippocampus structure and function, and neuronal loss, alcoholic cardiomyopathy, and muscle damage. Further, we have reviewed the role of altered microRNAs in the circulation, teratogenic effects of alcohol, and during maternal or paternal alcohol consumption

Extracellular Vesicles in Physiology, Pathology, and Therapy of the Immune and Central Nervous System, with Focus on Extracellular Vesicles Derived from Mesenchymal Stem Cells as Therapeutic Tools

Extracellular vesicles (EVs) are membrane-surrounded structures released by most cell types. They are characterized by a specific set of proteins, lipids and nucleic acids. EVs have been recognized as potent vehicles of intercellular communication to transmit biological signals between cells. In addition, pathophysiological roles of EVs in conditions like cancer, infectious diseases and neurodegenerative disorders are well established. In recent years focus has been shifted on therapeutic use of stem cell derived-EVs. Use of stem cell derived-EVs present distinct advantage over the whole stem cells as EVs do not replicate and after intravenous administration, they are less likely to trap inside the lungs. From the therapeutic perspective, the most promising cellular sources of EVs are mesenchymal stem cells (MSCs), which are easy to obtain and maintain. Therapeutic activity of MSCs has been shown in numerous animal models and the beneficial paracrine effect of MSCs may be mediated by EVs. The various components of MSC derived-EVs such as proteins, lipids and RNA might play a specific therapeutic role. In this review, we characterize the role of EVs in immune and central nervous system (CNS); present evidences for defective signalling of these vesicles in neurodegeneration and therapeutic role of EVs in CNS

Exosomes from lung and breast milk – regulators of immune responses

Exosomes are key mediators of intercellular communication with the capacity to regulate immune responses, locally and distally. Most knowledge on exosomal function has been gained from exosomes generated from in vitro cell cultures, which has helped define the role of exosomes from specific cell types. However, studying ex-vivo isolated exosomes from body fluids are more likely to yield clues about their in vivo role. This thesis aimed to gain knowledge regarding the role of human- derived exosomes from two important organs with a well-equipped immune system, namely the lung and the mammary gland. In study I we studied exosomes from bronchoalveolar lavage fluid (BALF) of patients with pulmonary sarcoidosis and healthy individuals. We detected elevated levels of exosomes with an altered exosome protein profile in BALF from patients compared to exosomes from healthy controls. Exosomes isolated from patients exhibited pro- inflammatory functions seen by their ability to induce inflammatory cytokine release (IFNγ and IL-13) in autologous peripheral blood mononuclear cells (PBMCs) and (IL- 8) in the bronchial epithelial cell line (BECs) 16HB14. These data suggest that exosomes may contribute to the inflammatory state of sarcoidosis. In order to investigate the specificity of the findings in study I relative to other inflammatory settings, we performed analysis of BALF exosomes from asthmatics. In study II we found that several surface proteins (CD36, CD63 and CD81) were upregulated on BALF exosomes from asthmatics during steady state and after allergen challenge compared to healthy controls. In addition, BALF-derived exosomes from asthmatics at steady state and after allergen challenge could stimulate secretion of leukotrienes (LTs) and IL-8 in BECs, suggesting a pro- inflammatory function of BALF exosomes in asthmatic inflammation. Breastfeeding is associated with health benefits for the child with possible effects on allergy development. Variations in immune-composition in breast milk between mothers could potentially result in differences in allergic outcome. Therefore, in study III we sought to determine whether maternal sensitization and lifestyle could affect exosome composition in breast milk. Accordingly, we found that both maternal immune status and environmental factors have a differential impact on subpopulations of exosomes in breast milk with potential effects on allergic outcome of the child as a consequence. In study IV we aimed to study the effect of breast milk-exosomes on HIV infection based on findings suggesting a protective role of breastfeeding on HIV infection from mother-to-child. We report a protective role of human breast milk exosomes on HIV infection of dendritic cells and subsequent transfer and infectivity of T cells. Thus, we suggest that breast milk-exosomes might constitute one protective factor in milk against HIV infection in the child. In conclusion, this thesis provides important insights into the composition and function of exosomes from human BALF and breast milk. Furthermore, it sheds light on how different immunological conditions can perturb the function and phenotype of exosomes in vivo. In the future, this could have important implications for the development of novel treatments against inflammatory diseases using exosomes as targets or therapeutic vehicles