In vitro neuronal network activity as a new functional diagnostic system to detect effects of Cerebrospinal fluid from autoimmune encephalitis patients

Henner Koch,Christian Elger,Christian G Bien,Michael Malter,Stephan Theiss,Peter Körtvelyessy,Cristina E Niturad,Marcel Dihné,Klaus-Peter Wandinger,Angela Vincent,Holger Lerche

doi:10.1038/s41598-019-41849-z

Abstract

The intent of this study was to investigate if cerebrospinal fluid (CSF) from autoimmune encephalitis (AE) patients regulates in vitro neuronal network activity differentially to healthy human control CSF (hCSF). To this end, electrophysiological effects of CSF from AE patients or hCSF were measured by in vitro neuronal network activity (ivNNA) recorded with microelectrode arrays (MEA). CSF from patients with either N-methyl-D-aspartate-receptor-antibody (pCSFNMDAR, n = 7) or Leucine-rich-glioma-inactivated-1-Ab (pCSFLGI1, n = 6) associated AE suppressed global spiking activity of neuronal networks by a factor of 2.17 (p < 0.05) or 2.42 (p < 0.05) compared to hCSF. The former also suppressed synchronous network bursting by a factor of 1.93 (p < 0.05) in comparison to hCSF (n = 13). As a functional diagnostic test, this parameter reached a sensitivity of 86% for NMDAR-Ab- and 100% for LGI1-Ab-associated AE vs. hCSF at a specificity of 85%. To explore if modulation at the NMDAR influences effects of hCSF or pathological CSF, we applied the NMDAR-antagonist 2-Amino-5-phosphono-pentanoic acid (AP5). In CSF from NMDAR-Ab-associated AE patients, spike rate reduction by AP5 was more than 2-fold larger than in hCSF (p < 0.05), and network burst rate reduction more than 18-fold (p < 0.01). Recording ivNNA might help discriminating between functional effects of CSF from AE patients and hCSF, and thus could be used as a functional diagnostic test in AE. The pronounced suppression of ivNNA by CSF from NMDAR-Ab-associated AE patients and simultaneous antagonism at the NMDAR by AP5, particularly in burst activity, compared to hCSF plus AP5, confirms that the former contains additional ivNNA-suppressing factors.

Highlights

We investigated, if in vitro neuronal network activity (ivNNA) is able to discriminate between cerebrospinal fluid (CSF) from patients with autoimmune encephalitis (AE) associated with LGI1-Abs (n = 6) and human control CSF (hCSF) (n = 13) and consolidate the data concerning AE associated with NMDAR-Abs (n = 7)
We show that ivNNA of primary neuronal mouse cultures measured by microelectrode arrays (MEA) is suppressed by pCSFNMDAR and pCSFLGI1 in comparison to hCSF
PCSFNMDAR did not significantly change ivNNA compared to artificial CSF (aCSF), suppressed electrophysiological parameters compared to hCSF

Summary

Introduction

Pathological results from MRI, electroencephalography and CSF are not AE specific, and autoimmune-Abs are sometimes clinically irrelevant, for instance in patients with small lung cancer and Hu-Abs without neurological disease[4]. We could show that ivNNA measured by the MEA system (multiple extracellular electrodes that detect neuronal spiking activity, Fig. 1) is able to discriminate between hCSF or CSF from different central nervous system diseases[8,9], including one case with NMDAR-Ab-associated encephalitis[10]. We investigated, if ivNNA is able to discriminate between CSF from patients with AE associated with LGI1-Abs (n = 6) and hCSF (n = 13) and consolidate the data concerning AE associated with NMDAR-Abs (n = 7). We investigated effects on ivNNA by a CASPR2-Ab CSF sample

Methods

Results

Conclusion