Referenced in: none

Automatically associated channels: Kv1.4 , Kv3.1 , Kv4.2

Title: Anti-DPPX encephalitis: pathogenic effects of antibodies on gut and brain neurons.

Authors: Johannes Piepgras, Markus Höltje, Klaus Michel, Qin Li, Carolin Otto, Christoph Drenckhahn, Christian Probst, Michael Schemann, Sven Jarius, Winfried Stöcker, Bettina Balint, Hans-Michael Meinck, Ralph Buchert, Josep Dalmau, Gudrun Ahnert-Hilger, Klemens Ruprecht

Journal, date & volume: Neurology, 2015 Sep 8 , 85, 890-7

PubMed link: http://www.ncbi.nlm.nih.gov/pubmed/26291285

Abstract
To characterize pathogenic effects of antibodies to dipeptidyl-peptidase-like protein 6 (DPPX), a subunit of Kv4.2 potassium channels, on gut and brain neurons.We identified a new patient with anti-DPPX encephalitis and analyzed the effects of the patient's serum and purified immunoglobulin G (IgG), and of serum of a previous patient with anti-DPPX encephalitis, on the activity of enteric neurons by voltage-sensitive dye imaging in guinea pig myenteric and human submucous plexus preparations. We studied the subcellular localization of DPPX by immunocytochemistry in cultured murine hippocampal neurons using sera of 4 patients with anti-DPPX encephalitis. We investigated the influence of anti-DPPX-containing serum and purified IgG on neuronal surface expression of DPPX and Kv4.2 by immunoblots of purified murine hippocampal neuron membranes.The new patient with anti-DPPX encephalitis presented with a 2-month episode of diarrhea, which was followed by tremor, disorientation, and mild memory impairment. Anti-DPPX-IgG-containing sera and purified IgG increased the excitability and action potential frequency of guinea pig and human enteric nervous system neurons. Patient sera revealed a somatodendritic and perisynaptic neuronal surface staining that colocalized with the signal of commercial anti-DPPX and Kv4.2 antibodies. Incubation of hippocampal neurons with patient serum and purified IgG resulted in a decreased expression of DPPX and Kv4.2 in neuronal membranes.Hyperexcitability of enteric nervous system neurons and downregulation of DPPX and Kv4.2 from hippocampal neuron membranes mirror the clinical phenotype of patients with anti-DPPX encephalitis and support a pathogenic role of anti-DPPX antibodies in anti-DPPX encephalitis.