Modeling multiple sclerosis in laboratory animals

Inflammatory demyelinating disease of the central nervous system is one of the most frequent causes of neurological disability in young adults. While in situ analysis and in vitro models do shed some light onto the processes of tissue damage and cellular interactions, the development of neuroinflammation and demyelination is a far too complex process to be adequately modeled by simple test tube systems. Thus, animal models using primarily genetically modified mice have been proven to be of paramount importance. In this chapter, we discuss recent advances in modeling brain diseases focusing on murine models and report on new tools to study the pathogenesis of complex diseases such as multiple sclerosi

Antigen presentation in autoimmunity and CNS inflammation: how T lymphocytes recognize the brain

The central nervous system (CNS) is traditionally viewed as an immune privileged site in which overzealous immune cells are prevented from doing irreparable damage. It was believed that immune responses occurring within the CNS could potentially do more damage than the initial pathogenic insult itself. However, virtually every aspect of CNS tissue damage, including degeneration, tumors, infection, and of course autoimmunity, involves a significant cellular inflammatory component. While the blood-brain barrier (BBB) inhibits diffusion of hydrophilic (immune) molecules across brain capillaries, activated lymphocytes readily pass the endothelial layer of postcapillary venules without difficulty. In classic neuro-immune diseases such as multiple sclerosis or acute disseminated encephalomyelitis, it is thought that neuroantigen-reactive lymphocytes, which have escaped immune tolerance, now invade the CNS and are responsible for tissue damage, demyelination, and axonal degeneration. The developed animal model for these disorders, experimental autoimmune encephalomyelitis (EAE), reflects many aspects of the human conditions. Studies in EAE proved that auto-reactive encephalitogenic T helper (Th) cells are responsible for the onset of the disease. Th cells recognize their cognate antigen (Ag) only when presented by professional Ag-presenting cells in the context of major histocompatibility complex class II molecules. The apparent target structures of EAE immunity are myelinating oligodendrocytes, which are not capable of presenting Ag to invading encephalitogenic T cells. A compulsory third party is thus required to mediate between the attacking T cells and the myelin-expressing target. This review will discuss the recent advances in this field of research and we will discuss the journey of an auto-reactive T cell from its site of activation into perivascular spaces and further into the target tissu

Experimental Autoimmune Encephalitis and Inflammation in the Absence of Interleukin-12

IL-12 is considered a critical proinflammatory cytokine for autoimmune diseases such as multiple sclerosis and its animal model, experimental autoimmune encephalomyelitis (EAE). IL-12 is a heterodimer composed of a p35 subunit and a common p40 subunit shared by other cytokines. Both IL-12 p40–/– and p35–/– mice fail to produce IL-12 p70 heterodimer. However, in contrast to p40–/– mice, p35–/– mice are highly susceptible to the induction of EAE, establishing that IL-12 p70 is not essential for the development of EAE. When compared with wild-type mice, both p40–/– and p35–/– mice show deficiencies in primary IFN-γ responses by lymph node cells. Expression profiling of the inflamed CNS revealed that Th2 cytokines such as IL-4 and IL-10 are upregulated in p35–/– mice, whereas LT-α and TNF-α levels are reduced. These studies show that a molecule other than IL-12 p70, which uses the p40 subunit, fulfills the functions previously attributed to IL-12 with regard to the development and pathogenesis of this autoimmune disease

LifeTime and improving European healthcare through cell-based interceptive medicine

Here we describe the LifeTime Initiative, which aims to track, understand and target human cells during the onset and progression of complex diseases, and to analyse their response to therapy at single-cell resolution. This mission will be implemented through the development, integration and application of single-cell multi-omics and imaging, artificial intelligence and patient-derived experimental disease models during the progression from health to disease. The analysis of large molecular and clinical datasets will identify molecular mechanisms, create predictive computational models of disease progression, and reveal new drug targets and therapies. The timely detection and interception of disease embedded in an ethical and patient-centred vision will be achieved through interactions across academia, hospitals, patient associations, health data management systems and industry. The application of this strategy to key medical challenges in cancer, neurological and neuropsychiatric disorders, and infectious, chronic inflammatory and cardiovascular diseases at the single-cell level will usher in cell-based interceptive medicine in Europe over the next decade

Mature oligodendrocytes actively increase in vivo cytoskeletal plasticity following CNS damage

Background: Oligodendrocytes are myelinating cells of the central nervous system which support functionally, structurally, and metabolically neurons. Mature oligodendrocytes are generally believed to be mere targets of destruction in the context of neuroinflammation and tissue damage, but their real degree of in vivo plasticity has become a matter of debate. We thus investigated the in vivo dynamic, actin-related response of these cells under different kinds of demyelinating stress. Methods: We used a novel mouse model (oLucR) expressing luciferase in myelin oligodendrocyte glycoproteinpositive oligodendrocytes under the control of a beta-actin promoter. Activity of this promoter served as surrogate for dynamics of the cytoskeleton gene transcription through recording of in vivo bioluminescence following diphtheria toxin-induced oligodendrocyte death and autoimmune demyelination. Cytoskeletal gene expression was quantified from mature oligodendrocytes directly isolated from transgenic animals through cell sorting. Results: Experimental demyelinating setups augmented oligodendrocyte-specific in vivo bioluminescence. These changes in luciferase signal were confirmed by further ex vivo analysis of the central nervous system tissue from oLucR mice. Increase in bioluminescence upon autoimmune inflammation was parallel to an oligodendrocytespecific increased transcription of beta-tubulin. Conclusions: Mature oligodendrocytes acutely increase their cytoskeletal plasticity in vivo during demyelination. They are therefore not passive players under demyelinating conditions but can rather react dynamically to external insults

Deletion of Jun Proteins in Adult Oligodendrocytes Does Not Perturb Cell Survival, or Myelin Maintenance In Vivo

Oligodendrocytes, the myelin-forming glial cells of the central nervous system (CNS),are fundamental players in rapid impulse conduction and normal axonal functions. JunB and c-Jun are DNA-binding components of the AP-1 transcription factor, which is known to regulate different processes such as proliferation, differentiation, stress responses and death in several cell types, including cultured oligodendrocyte/lineage cells. By selectively inactivating Jun B and c-Jun in myelinating oligodendrocytes in vivo, we generated mutant mice that developed normally, and within more than 12 months showed normal ageing and survival rates. In the adult CNS, absence of JunB and c-Jun from mature oligodendrocytes caused low-grade glial activation without overt signs of demyelination or secondary leukocyte infiltration into the brain. Even after exposure to toxic or autoimmune oligodendrocyte insults, signs of altered oligodendrocyte viability were mild and detectable only upon cuprizone treatment. We conclude that JunB and c-Jun expression in post-mitotic oligodendrocytes is mostly dispensable for the maintainance of white matter tracts throughout adult life, even under demyelinating conditions

IL-27, but not IL-35, inhibits neuroinflammation through modulating GM-CSF expression

IL-27 and IL-35 are heterodimeric cytokines, members of the IL-12 family and considered to have immunomodulatory properties. Their role during neuroinflammation had been investigated using mutant mice devoid of either one of their subunits or lacking components of their receptors, yielding conflicting results. We sought to understand the therapeutic potential of IL-27 and IL-35 delivered by gene therapy in neuroinflammation. We constructed lentiviral vectors expressing IL-27 and IL-35 from a single polypeptide chain, and we validated in vitro their biological activity. We injected IL-27 and IL-35-expressing lentiviral vectors into the cerebrospinal fluid (CSF) of mice affected by experimental neuroinflammation (EAE), and performed clinical, neuropathological and immunological analyses. Both cytokines interfere with neuroinflammation, but only IL-27 significantly modulates disease development, both clinically and neuropathologically. IL-27 protects from autoimmune inflammation by inhibiting granulocyte macrophages colony-stimulating factor (GM-CSF) expression in CD4+ T cells and by inducing program death-ligand 1 (PD-L1) expression in both CNS-resident and CNS-infiltrating myeloid cells. We demonstrate here that IL-27 holds therapeutic potential during neuroinflammation and that IL-27 inhibits GM-CSF and induces pd-l1 mRNA in vivo