Alteration of the cytokine signature by various TLR ligands in different T cell populations in MOG37–50 and MOG35–55-induced EAE in C57BL/6 mice

Specific and Polyfunctional T Cell Response Against N-Methyl-d-aspartate Receptor in an Autoantibody-Mediated Encephalitis Model

BACKGROUND

Anti-N-Methyl-d-aspartate receptor (NMDAR) autoimmune encephalitis (NMDAR AE) is an autoimmune disease characterized by severe psychiatric and neurological symptoms. While the pathogenic role of antibodies (Abs) directed against the GluN1 subunit of NMDAR is well described in this disease, the immune mechanisms involved in the generation of the autoimmune B cell response, especially the role of T helper cells, are poorly understood. Previously, we developed a B-cell-mediated mouse model of NMDAR AE by immunization with a GluN1359-378 peptide that drives a series of symptoms that recapitulate AE such as anxiety behaviour and spatial memory impairment.

RESULTS

In this mouse model, we identified anti-GluN1-specific CD4+ but also CD8+ T cells in both spleen and meninges. T helper cells have a polyfunctional profile, arguing for a T and B cell crosstalk to generate anti-GluN1 pathogenic Abs. Interestingly, proteomic analysis of AE meninges showed enrichment of differentially expressed proteins in biological processes associated with B cell activation and cytokine signalling pathways.

CONCLUSIONS

This study identified, for the first time, a potential contribution of T helper cells in the pathology of NMDAR AE and paved the way for the development of future tolerogenic approaches to treat relapses.

Delimiting MOGAD as a disease entity using translational imaging

The first formal consensus diagnostic criteria for myelin oligodendrocyte glycoprotein antibody-associated disease (MOGAD) were recently proposed. Yet, the distinction of MOGAD-defining characteristics from characteristics of its important differential diagnoses such as multiple sclerosis (MS) and aquaporin-4 antibody seropositive neuromyelitis optica spectrum disorder (NMOSD) is still obstructed. In preclinical research, MOG antibody-based animal models were used for decades to derive knowledge about MS. In clinical research, people with MOGAD have been combined into cohorts with other diagnoses. Thus, it remains unclear to which extent the generated knowledge is specifically applicable to MOGAD. Translational research can contribute to identifying MOGAD characteristic features by establishing imaging methods and outcome parameters on proven pathophysiological grounds. This article reviews suitable animal models for translational MOGAD research and the current state and prospect of translational imaging in MOGAD.

Inflammatory Role of TLR-MyD88 Signaling in Multiple Sclerosis

Multiple sclerosis (MS) is a neuro-autoimmune and neurodegenerative disorder leading to chronic inflammation, demyelination, axonal, and neuronal loss in the central nervous system (CNS). Despite intense research efforts, the pathogenesis of MS still remains unclear. Toll-like receptors (TLRs) are a family of type I transmembrane receptors that play a crucial role in the innate immune response. Myeloid differentiation factor 88 (MyD88) is the adaptor of major TLRs. It has been widely considered that the TLR-MyD88 signaling pathway plays an important role in the occurrence and development of autoimmune disease. Data have revealed that the TLR-MyD88 signaling may be involved in the pathogenesis of MS and experimental autoimmune encephalomyelitis (EAE), an animal model for MS, by regulating the antigen presentation of dendritic cells, the integrity of blood-brain barrier (BBB), and the activation of T cells and B cells. Here, we summarize the role of TLRs and MyD88 in MS and discuss the possible therapies that are based on these molecules.

CCR7 on CD4+ T Cells Plays a Crucial Role in the Induction of Experimental Autoimmune Encephalomyelitis

Multiple sclerosis (MS) is the most common chronic inflammatory demyelinating disease of the CNS. Myelin-specific CD4⁺ Th lymphocytes are known to play a major role in both MS and its animal model experimental autoimmune encephalomyelitis (EAE). CCR7 is a critical element for immune cell trafficking and recirculation, that is, lymph node homing, under homeostatic conditions; blocking CCR7⁺ central memory cells from egress of lymph nodes is a therapeutic approach in MS. To define the effect of CD4⁺ T cell-specific constitutive deletion of CCR7 in the priming and effector phase in EAE, we used an active EAE approach in T cell reconstituted Rag1^-/- mice, as well as adoptive transfer EAE, in which mice received in vitro-primed CCR7^-/- or CCR7^+/+ myelin Ag TCR-transgenic 2d2 Th17 cells. Two-photon laser scanning microscopy was applied in living anesthetized mice to monitor the trafficking of CCR7-deficient and wild-type CD4⁺ T cells in inflammatory lesions within the CNS. We demonstrate that CD4⁺ T cell-specific constitutive deletion of CCR7 led to impaired induction of active EAE. In adoptive transfer EAE, mice receiving in vitro-primed CCR7^-/- 2d2 Th17 cells showed similar disease onset as mice adoptively transferred with CCR7^+/+ 2d2 Th17 cells. Using two-photon laser scanning microscopy CCR7^-/- and CCR7^+/+ CD4⁺ T cells did not reveal differences in motility in either animal model of MS. These findings indicate a crucial role of CCR7 in neuroinflammation during the priming of autoimmune CD4⁺ T cells but not in the CNS.