Forkhead box versus NF-κB hippocampal snRNA-seq profiles distinguish anti-Drebrin- and anti-GAD65-positive encephalitis.

Abstract

Background and objectives: Autoantibodies (ABs) against intracellular proteins, including glutamate-decarboxylase 65 (anti-GAD65), are increasingly recognized in autoimmune and limbic encephalitis (AE/LE). Anti-GAD65 LE frequently progresses to severe temporal lobe epilepsy (TLE), neuropathologically characterized by hippocampal sclerosis (HS) and variable infiltration of cytotoxic T lymphocytes (CTLs). Recently, we have identified Drebrin (DBN) as a new intracellular target protein of ABs in index patients with suspected AE. Here, we aim to characterize key molecular and cellular signatures of hippocampal tissue from anti-GAD65- (GAD65-TLE) versus anti-DBN-positive TLE (DBN-TLE) patients correlated to clinical parameters.

Methods: We examined hippocampal neuropathology and performed exploratory single-nucleus RNA sequencing (snRNA-seq) of hippocampal tissue from DBN- and GAD65-TLE patients, integrated with key clinical data from a large patient cohort.

Results: Although the hippocampi of the two patient groups were neuropathologically virtually indistinguishable, exploratory snRNA-seq revealed distinct transcriptional programs. DBN-TLE patients (n = 2) showed transcriptional signatures enriched for forkhead box (Fox) transcription factor family, whereas GAD65-TLE patients (n = 2) displayed transcriptional signatures enriched for transcripts related to NF-κB- signaling. In a larger cohort, DBN-TLE patients (n = 22) showed significantly more favorable pharmacological responsiveness than GAD65-TLE patients (n = 35), who were largely pharmacoresistant. Notably, in a T cell-mediated mouse model for LE, similar inflammatory programs were dynamically regulated.

Conclusion: These findings provide a discovery-based transcriptomic signatures of rare autoimmune hippocampal tissue, revealing distinct immune-associated transcriptional states in anti-DBN- versus anti-GAD65-positive AE/TLE patients despite virtually indistinguishable hippocampal pathology in both groups and support further investigations of disease-specific therapeutic strategies.