ABSTRACT
Background and objectives: B cell depleting anti-CD20 monoclonal antibodies (aCD20 mAbs) are highly effective in treatment of multiple sclerosis (MS) but fail to halt the formation of meningeal ectopic lymphoid tissue (mELT) in the murine model experimental autoimmune encephalomyelitis (EAE). While mELT can be examined in EAE, it is not accessible in vivo in MS patients. Our key objectives were to compare the immune cells in cerebrospinal fluid (CSF), which is accessible in patients, with those in mELT, and to study the effects of aCD20 mAbs on CSF and mELT in EAE. Methods: Applying single cell RNA sequencing, we compared gene expression profiles in immune cells from (1) CSF with mELT and (2) aCD20 mAbs treated with control treated mice in a spontaneous 2D2xTh EAE model. Results: The immune cell composition in CSF and mELT was very similar. Gene expression profiles and pathway enrichment analysis revealed no striking differences between the two compartments. aCD20 mAbs led not only to a virtually complete depletion of B cells in the CSF but also to a reduction of naïve CD4+ T cells and marked increase of macrophages. No remarkable differences in regulated genes or pathways were observed. Discussion: Our results suggest that immune cells in the CSF may serve as a surrogate for mELT in EAE. Future studies are required to confirm this in MS patients. The observed increase of macrophages in B cell depleted CSF is a novel finding and requires verification in CSF of aCD20 mAbs treated MS patients. Due to unresolved technical challenges, we were unable to study the effects of aCD20 mAbs on mELT. This should be addressed in future studies.
Subject(s)
B-Lymphocytes , Encephalomyelitis, Autoimmune, Experimental , Meninges , Single-Cell Analysis , Animals , Encephalomyelitis, Autoimmune, Experimental/immunology , Encephalomyelitis, Autoimmune, Experimental/cerebrospinal fluid , Mice , Meninges/immunology , Meninges/pathology , B-Lymphocytes/immunology , Female , Tertiary Lymphoid Structures/immunology , Mice, Inbred C57BL , Antibodies, Monoclonal/immunology , Transcriptome , Gene Expression Profiling , Antigens, CD20/immunology , Cerebrospinal Fluid/immunology , Disease Models, Animal , Multiple Sclerosis/immunology , Multiple Sclerosis/cerebrospinal fluidABSTRACT
BACKGROUND AND OBJECTIVES: To investigate whether the formation or retention of meningeal ectopic lymphoid tissue (mELT) can be inhibited by the sphingosine 1-phosphate receptor 1,5 modulator siponimod (BAF312) in a murine model of multiple sclerosis (MS). METHODS: A murine spontaneous chronic experimental autoimmune encephalomyelitis (EAE) model, featuring meningeal inflammatory infiltrates resembling those in MS, was used. To prevent or treat EAE, siponimod was administered daily starting either before EAE onset or at peak of disease. The extent and cellular composition of mELT, the spinal cord parenchyma, and the spleen was assessed by histology and immunohistochemistry. RESULTS: Siponimod, when applied before disease onset, ameliorated EAE. This effect was also present, although less prominent, when treatment started at peak of disease. Treatment with siponimod resulted in a strong reduction of the extent of mELT in both treatment paradigms. Both B and T cells were diminished in the meningeal compartment. DISCUSSION: Beneficial effects on the disease course correlated with a reduction in mELT, suggesting that inhibition of mELT may be an additional mechanism of action of siponimod in the treatment of EAE. Further studies are needed to establish causality and confirm this observation in MS.
Subject(s)
Azetidines/pharmacology , Benzyl Compounds/pharmacology , Encephalomyelitis, Autoimmune, Experimental , Meninges/drug effects , Multiple Sclerosis , Sphingosine 1 Phosphate Receptor Modulators/pharmacology , Tertiary Lymphoid Structures , Animals , Disease Models, Animal , Encephalomyelitis, Autoimmune, Experimental/complications , Encephalomyelitis, Autoimmune, Experimental/drug therapy , Encephalomyelitis, Autoimmune, Experimental/prevention & control , Humans , Meninges/immunology , Mice , Multiple Sclerosis/complications , Multiple Sclerosis/drug therapy , Multiple Sclerosis/prevention & control , Tertiary Lymphoid Structures/drug therapy , Tertiary Lymphoid Structures/etiology , Tertiary Lymphoid Structures/prevention & controlABSTRACT
OBJECTIVE: To investigate whether anti-CD20 B-cell-depleting monoclonal antibodies (ÉCD20 mAbs) inhibit the formation or retention of meningeal ectopic lymphoid tissue (mELT) in a murine model of multiple sclerosis (MS). METHODS: We used a spontaneous chronic experimental autoimmune encephalomyelitis (EAE) model of mice with mutant T-cell and B-cell receptors specific for myelin oligodendrocyte glycoprotein (MOG), which develop meningeal inflammatory infiltrates resembling those described in MS. ÉCD20 mAbs were administered in either a preventive or a treatment regimen. The extent and cellular composition of mELT was assessed by histology and immunohistochemistry. RESULTS: ÉCD20 mAb, applied in a paradigm to either prevent or treat EAE, did not alter the disease course in either condition. However, ÉCD20 mAb depleted virtually all B cells from the meningeal compartment but failed to prevent the formation of mELT altogether. Because of the absence of B cells, mELT was less densely populated with immune cells and the cellular composition was changed, with increased neutrophil granulocytes. CONCLUSIONS: These results demonstrate that, in CNS autoimmune disease, meningeal inflammatory infiltrates may form and persist in the absence of B cells. Together with the finding that ÉCD20 mAb does not ameliorate spontaneous chronic EAE with mELT, our data suggest that mELT may have yet unknown capacities that are independent of B cells and contribute to CNS autoimmunity.
