Jackie Weiss1, Ramona Miske2, Madeleine Scharf2, Kathrin Borowski3, Ina Specht4, Merle Corty3, Monika-Johanna Loritz5, Frederik Rombach5, Guy Laureys6, Nadine Rochow2, Christiane Radzimski2, Linda Schnitter2, Dominica Ratuszny8, Thomas Skripuletz8, Mike P. Wattjes9, Stefanie Hahn2, Yvonne Denno2, Khadija Guerti10, Mattijs Oyaert7, Farid Benkhadra11, Corinna Bien12, Sophie Nitsch13, Klaus-Peter Wandinger14, Vincent van Pesch15, Christian Probst2, Bianca Teegen3, Lars Komorowski2, Kurt-Wolfram Sühs8
1EUROIMMUN US, 2Institute for Experimental Immunology, affiliated to EUROIMMUN Medizinische Labordiagnostika AG, 3Clinical Immunological Laboratory Prof. Dr. Med. Winfried Stöcker, 4Agaplesion Diakonieklinikum Rotenburg, 5Städtisches Klinikum Karlsruhe, 6Department of Neurology, 7Department of Laboratory Medicine, Ghent University Hospital, 8Department of Neurology, 9Department of Neuroradiology, Hannover Medical School, 10Department of Clinical Chemistry, Antwerp University Hospital, 11Department of Clinical Biology, Centre Hospitalier de Luxembourg, 12Laboratory Krone, 13Division of Neuropathology and Neurochemistry, Department of Neurology, Medical University of Vienna, 14Institute of Clinical Chemistry, University Hospital Schleswig-Holstein, 15Department of Neurology, Cliniques Universitaires Saint-Luc, Université Catholique de Louvain (UCLouvain)
Objective:
We report the identification of diacylglycerol lipase α (DAGLA) as target autoantigen in severe cerebellitis.
Design/Methods:
Serum and cerebrospinal fluid samples from four index patients were subjected to comprehensive autoantibody screening by indirect immunofluorescence assay (IFA), showing an unclassified pattern on tissue substrates. Immunoprecipitation followed by mass spectrometry was used to identify the autoantibody target, which was verified by recombinant protein assays. Sera from patients with various neurological symptoms showing a similar tissue IFA pattern as the index patient samples, and healthy control sera were analyzed in recombinant cell-based IFA using HEK293 cells expressing the identified protein. Epitope characterization was performed using different immunoassays.
Results:
All four index patients suffered from rapidly progressive midline-accentuated cerebellar syndrome. Severe cerebellar atrophy developed in 3/4 patients within six months. In IFA on cerebellar tissue sections, all patient samples revealed a consistent IgG reactivity with the molecular layer. DAGLA was identified as the target antigen and confirmed by competitive inhibition experiments and RC-IFA with recombinant DAGLA. Among disease and healthy control sera, additional anti-DAGLA positive samples were detected by RC-IFA, including patients with different clinical phenotypes compared to the index patients, but only one with tissue IFA-positive CSF. In ELISA using six DAGLA fragments, none of the cerebellitis patient samples displayed a positive reaction, while 16/17 DC sera and the anti-DAGLA-positive HC serum reacted with the C-terminal, intracellular DAGLA aa 583–1042 fragment. In immunoprecipitations or RC-IFA with C-terminally truncated DAGLA variants lacking the C-terminal intracellular domain, only the sera or CSF of the cerebellitis patients reacted positively.
Conclusions:
Our data indicate the existence of at least two subtypes of anti-DAGLA autoantibodies targeting different epitopes and having distinguishable clinical associations. We propose that anti-DAGLA autoantibodies detected in CSF showing a characteristic tissue IFA pattern, represent novel biomarkers for a severe form of autoimmune cerebellitis.
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