Cervical lymph nodes and ovarian teratomas as germinal centres in NMDA receptor-antibody encephalitis

Abstract

Autoantibodies against the extracellular domain of the N-methyl-d-aspartate receptor (NMDAR) NR1 subunit cause a severe and common form of encephalitis. To better understand their generation, we aimed to characterize and identify human germinal centres actively participating in NMDAR-specific autoimmunization by sampling patient blood, CSF, ovarian teratoma tissue and, directly from the putative site of human CNS lymphatic drainage, cervical lymph nodes. From serum, both NR1-IgA and NR1-IgM were detected more frequently in NMDAR-antibody encephalitis patients versus controls (both P < 0.0001). Within patients, ovarian teratoma status was associated with a higher frequency of NR1-IgA positivity in serum (OR = 3.1; P < 0.0001) and CSF (OR = 3.8, P = 0.047), particularly early in disease and before ovarian teratoma resection. Consistent with this immunoglobulin class bias, ovarian teratoma samples showed intratumoral production of both NR1-IgG and NR1-IgA and, by single cell RNA sequencing, contained expanded highly-mutated IgA clones with an ovarian teratoma-restricted B cell population. Multiplex histology suggested tertiary lymphoid architectures in ovarian teratomas with dense B cell foci expressing the germinal centre marker BCL6, CD21+ follicular dendritic cells, and the NR1 subunit, alongside lymphatic vessels and high endothelial vasculature. Cultured teratoma explants and dissociated intratumoral B cells secreted NR1-IgGs in culture. Hence, ovarian teratomas showed structural and functional evidence of NR1-specific germinal centres. On exploring classical secondary lymphoid organs, B cells cultured from cervical lymph nodes of patients with NMDAR-antibody encephalitis produced NR1-IgG in 3/7 cultures, from patients with the highest serum NR1-IgG levels (P < 0.05). By contrast, NR1-IgG secretion was observed neither from cervical lymph nodes in disease controls nor in patients with adequately resected ovarian teratomas. Our multimodal evaluations provide convergent anatomical and functional evidence of NMDAR-autoantibody production from active germinal centres within both intratumoral tertiary lymphoid structures and traditional secondary lymphoid organs, the cervical lymph nodes. Furthermore, we develop a cervical lymph node sampling protocol that can be used to directly explore immune activity in health and disease at this emerging neuroimmune interface.

Rituximab abrogates aquaporin-4–specific germinal center activity in patients with neuromyelitis optica spectrum disorders

“…Written informed consent was obtained from all participants, including 14 disease controls (with autoimmune encephalitis, n = 11, or migraine, n = 3; select controls also in ref. 47 ). For patients and controls, demographics, past and current immunotherapies, and sampling times are detailed in SI Appendix , Tables 1 and 2 .…”

Antibodies Against Glutamic Acid Decarboxylase 65 Are Locally Produced in the CSF and Arise During Affinity Maturation

“… 26 In NMDAR encephalitis, tertiary lymphoid architectures in ovarian teratomas were suggested, and a production of NMDAR autoantibodies was detected from cultured teratoma explants and dissociated intratumoral B cells and from 3/7 cultures of cervical lymph nodes. 27 Our data point to a relevance of germinal center reactions also in GAD65-Ab SD.…”

Cytokine/chemokine levels in the CSF and serum of anti-NMDAR encephalitis: A systematic review and meta-analysis

“…Additionally, because T cells are predominantly found in the cerebrospinal fluid (CSF) of affected people while B cells are scarce ( 17 ), some prior studies have suggested that NMDAR-E onset could be potentially triggered by the activation of T cells in the periphery and CNS ( 13 ). Indeed, current pathological examination and postmortem reports further support the observation that the different effector T helper (Th) cells, such as Th1 and Th17 cells, could extensively be infiltrated in the tissues ( 11 , 13 , 14 , 18 ). In particular, previous studies have demonstrated that Th cells can significantly enhance antibody-secreting cell (ASC)-mediated antibody responses, as mice were actively immunized with conformationally stabilized NMDAR protein and both ASCs and CD4+ T cells demonstrated extensive infiltration into the hippocampus ( 19 ).…”

“…Furthermore, prior studies in mouse models have revealed that autoimmune antibodies can activate both astrocytes and microglia, and then these cells can release cytokines such as IL-1β and IL-12 to promote the epileptic occurrence and enhance the immune effects of Th1 cells ( 77 , 78 ). In addition, activated follicular helper T cells and follicular dendritic cells can release CXCL13 to promote the immune response ( 18 ). These immune cells can facilitate inflammation, especially in the early stages of autoimmune encephalitis ( 30 , 31 ).…”