Project description:The present study had the purpose to analyze the transcriptional state of oligodendrocytes in an animal model of multiple scleroris resembling autoimmune neuroinflammation and compared with control mice treated with ovalbumin. The results revealed that oligodendrocytes from the EAE (experimental autoimmune encephalomyelitis) model upregulate genes that are involved in immune processes providing evidence that oligodendrocytes can develop an immune phenotype in particular neuroinflammatory conditions.
Project description:Autoimmune diseases such as multiple sclerosis (MS) develop because of failed peripheral immune tolerance for a specific self-antigen (Ag). Numerous approaches for Ag-specific suppression of autoimmune neuroinflammation have been proven in experimental autoimmune encephalomyelitis (EAE), an animal model of MS. One such approach is intravenous (i.v.) tolerance induction by injecting a myelin Ag used for EAE induction. However, the translation of this and similar experimental strategies into therapy for MS has been hampered by uncertainty regarding relevant myelin Ags in MS patients. To address this issue, we developed a therapeutic strategy that relies on oligodendrocyte (Ol)-derived extracellular vesicles (Ol-EVs), which naturally contain multiple myelin Ags. Ol-EVs injected i.v. suppressed disease in a myelin Ag-dependent manner, both prophylactically and therapeutically, in several EAE models. The treatment was safe and restored immune tolerance by inducing immunosuppressive monocytes and apoptosis of autoreactive encephalitogenic CD4+ T cells. Finally, we show that human Ols also release EVs containing most relevant myelin Ags, providing a basis for their use in MS therapy. These findings introduce an approach for suppressing central nervous system autoimmunity in a myelin Ag-specific manner.
Project description:Microglial activation during neuroinflammation is crucial for coordinating the immune response against neuronal tissue and the initial response of microglia determines the severity of neuroinflammatory diseases. CD83 has been associated with early activation of microglia in various disease settings albeit its functional relevance for microglial biology was still elusive. Thus, we conducted a thorough assessment of CD83 regulation in microglia as well as its impact on microglial mediated neuroinflammation. Here, we describe for the first time that CD83 expression in microglia is not only associated with cellular activation but also with pro-resolving functions. Conditional deletion of CD83 causes malfunctioning responses to myelin debris, which results in an over-activated state during autoimmune neuroinflammation. Subsequently, CD83-deficient microglia recruit more pathogenic immune cells to the central nervous system and deteriorate resolving mechanism, which exacerbates the disease. Thus, CD83 in microglia orchestrates cellular activation and consequently, also resolution of neuroinflammation.
Project description:STAT5 plays a critical role in mediating cellular responses following cytokine stimulation. The activated STAT5 proteins can form dimers and tetramers with distinct biological functions. The role of STAT5 tetramerization in autoimmune-mediated neuroinflammation has not been investigated. Using the STAT5 tetramer-deficient Stat5a-Stat5b N-domain double knock-in (DKI) mouse strain, we report here that STAT5 tetramers promote the pathogenesis of experimental autoimmune encephalomyelitis (EAE). The mild EAE phenotype observed in DKI mice correlates with the impaired extravasation of pathogenic Th17 cells and interactions between Th17 cells and monocyte-derived cells (MDCs) in the meninges. We further demonstrated that STAT5 tetramerization regulates the GM-CSF-dependent production of CCL17 by MDCs. Importantly, DKI Th17 cells expanded with CCL17 exhibit more severe EAE. Mechanistically, the effect of CCL17 is dependent on the activity of the integrin VLA-4. Thus, our study uncovered a novel GM-CSF-STAT5 tetramer-CCL17 pathway that promotes autoimmune neuroinflammation via the regulation of Th17 cell migration.
Project description:Tetramerization of Transcription Factor STAT5 in Monocytes Promotes Autoimmune-mediated Neuroinflammation via the Regulation of CCL17
Project description:A20 is a ubiquitin-modifying protein that negatively regulates canonical NF-κB signaling and mutations in A20/TNFAIP3 have been associated with a variety of autoimmune diseases, including multiple sclerosis (MS). We found that deletion of A20 in central nervous system (CNS) endothelial cells (BEC) enhances experimental autoimmune encephalomyelitis (EAE), a mouse model of MS. These mice showed increased numbers of CNS-infiltrating immune cells during neuroinflammation and in the steady state. While the integrity of the barrier was not impaired, we observed a strong activation of the endothelium in A20ΔBEC mice, with dramatically increased levels of the adhesion molecules ICAM-1 and VCAM-1. We furthermore discovered ICOSL as novel adhesion molecule expressed by A20-deficient BECs. Silencing of ICOSL in BECs ameliorated the severity of an active EAE disease in wildtype mice and significantly delayed the onset of symptom development. Furthermore, blocking of ICOSL on primary CNS-derived endothelial cells impaired the adhesion of different T cell populations to the monolayer. Taken together, we here report a novel function of A20-regulated ICOSL expressed on CNS endothelial cells during inflammation. We propose that BEC-ICOSL contributes to the firm adhesion of T cells to the barrier, promoting T cell transmigration into the CNS and eventually driving autoimmune neuroinflammation.
Project description:Genes and pathways in which inactivation dampens tissue inflammation present new opportunities for understanding the pathogenesis of common human inflammatory diseases, including inflammatory bowel disease, rheumatoid arthritis and multiple sclerosis. We identified a mutation in the gene encoding the deubiquitination enzyme USP15 (Usp15L749R) that protected mice against both experimental cerebral malaria (ECM) induced by Plasmodium berghei and experimental autoimmune encephalomyelitis (EAE). Combining immunophenotyping and RNA sequencing in brain (ECM) and spinal cord (EAE) revealed that Usp15L749R-associated resistance to neuroinflammation was linked to dampened type I interferon responses in situ. In hematopoietic cells and in resident brain cells, USP15 was coexpressed with, and functionally acted together with the E3 ubiquitin ligase TRIM25 to positively regulate type I interferon responses and to promote pathogenesis during neuroinflammation. The USP15-TRIM25 dyad might be a potential target for intervention in acute or chronic states of neuroinflammation.
Project description:Experimental autoimmune encephalomyelitis (EAE)-susceptible DA and EAE-resistant congenic R23 rats were immunized with myelin oligodendrocyte glycoprotein (MOG) to induce an autoimmune response.<br><br>Seven days later draining inguinal lymph nodes were removed. 2 conditions were examined: 'ex vivo' and 'MOG restimulated', which involved 24hrs of incubation with an encephalogenic MOG 91-108 peptide.<br><br>
Project description:Experimental autoimmune encephalomyelitis (EAE)-susceptible DA and EAE-resistant PVG rats were immunized with myelin oligodendrocyte glycoprotein (MOG) to induce an autoimmune response.<br>Seven days later draining inguinal lymph nodes were removed. 2 conditions were examined: 'ex vivo' and 'MOG restimulated', which involved 24hrs of incubation with an encephalogenic MOG 91-108 peptide.