Contribution of LTi and TH17 cells to B cell aggregate formation in the central nervous system in a mouse model of multiple sclerosis

• Published in: Journal of neuroinflammation 2019-05, Vol.16 (1), p.111-111, Article 111
• Main Authors: Schropp, Verena, Rohde, Jörn, Rovituso, Damiano M., Jabari, Samir, Bharti, Richa, Kuerten, Stefanie
• Format: Article
• Language: English
• Subjects: Animal models; Arthritis; B cells; CD3 antigen; CD4 antigen; CD5 antigen; Central nervous system; Cerebellum; Chemokines; Cortex; Cytokines; Development and progression; Diagnosis; Disease; EAE; Experimental allergic encephalomyelitis; Flow cytometry; Gene expression; Growth; Helper cells; Inflammation; Intestine; LTi cells; Lymph nodes; Lymphocytes; Lymphocytes B; Lymphocytes T; Lymphoid cells; Lymphoid tissue; Meninges; MP4; Multiple sclerosis; Myelin; Nervous system; Neurodegenerative diseases; Oligodendrocyte-myelin glycoprotein; Physiological aspects; Proteins; Ribonucleic acid; RNA; Spleen; T cells; TH17 cells
• ISSN: 1742-2094; 1742-2094
• DOI: 10.1186/s12974-019-1500-x

Background In a subgroup of patients suffering from progressive multiple sclerosis (MS), which is an inflammation-mediated neurodegenerative disease of the central nervous system (CNS), B cell aggregates were discovered within the meninges. Occurrence of these structures was associated with a more severe disease course and cortical histopathology. We have developed the B cell-dependent MP4-induced experimental autoimmune encephalomyelitis (EAE) as a mouse model to mimic this trait of the human disease. The aim of this study was to determine a potential role of lymphoid tissue inducer (LTi) and T.sub.H17 cells in the process of B cell aggregate formation in the MP4 model. Methods We performed flow cytometry of cerebellar and splenic tissue of MP4-immunized mice in the acute and chronic stage of the disease to analyze the presence of CD3.sup.-CD5.sup.-CD4.sup.+ROR[gamma]t.sup.+ LTi and CD3.sup.+CD5.sup.+CD4.sup.+ROR[gamma]t.sup.+ T.sub.H17 cells. Myelin oligodendrocyte glycoprotein (MOG):35-55-induced EAE was used as B cell-independent control model. We further determined the gene expression profile of B cell aggregates using laser capture microdissection, followed by RNA sequencing. Results While we were able to detect LTi cells in the embryonic spleen and adult intestine, which served as positive controls, there was no evidence for the existence of such a population in acute or chronic EAE in neither of the two models. Yet, we detected CD3.sup.-CD5.sup.-CD4.sup.-ROR[gamma]t.sup.+ innate lymphoid cells (ILCs) and T.sub.H17 cells in the CNS, the latter especially in the chronic stage of MP4-induced EAE. Moreover, we observed a unique gene signature in CNS B cell aggregates compared to draining lymph nodes of MP4-immunized mice and to cerebellum as well as draining lymph nodes of mice with MOG:35-55-induced EAE. Conclusion The absence of LTi cells in the cerebellum suggests that other cells might take over the function as an initiator of lymphoid tissue formation in the CNS. Overall, the development of ectopic lymphoid organs is a complex process based on an interplay between several molecules and signals. Here, we propose some potential candidates, which might be involved in the formation of B cell aggregates in the CNS of MP4-immunized mice. Keywords: EAE, LTi cells, MP4, MS, T.sub.H17 cells