Anti–neurofascin-155 IgG4 antibodies prevent paranodal complex formation in vivo
Constance Manso, … , Isabel Illa, Jérôme J. Devaux
Constance Manso, … , Isabel Illa, Jérôme J. Devaux
Published March 14, 2019
Citation Information: J Clin Invest. 2019;129(6):2222-2236. https://doi.org/10.1172/JCI124694.
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Research Article Autoimmunity Neuroscience

Anti–neurofascin-155 IgG4 antibodies prevent paranodal complex formation in vivo

Abstract

Neurofascin-155 (Nfasc155) is an essential glial cell adhesion molecule expressed in paranodal septate-like junctions of peripheral and central myelinated axons. The genetic deletion of Nfasc155 results in the loss of septate-like junctions and in conduction slowing. In humans, IgG4 antibodies against Nfasc155 are implicated in the pathogenesis of chronic inflammatory demyelinating polyneuropathy (CIDP). These antibodies are associated with an aggressive onset, a refractoriness to intravenous immunoglobulin, and tremor of possible cerebellar origin. Here, we examined the pathogenic effects of patient-derived anti-Nfasc155 IgG4. These antibodies did not inhibit the ability of Nfasc155 to complex with its axonal partners contactin-1 and CASPR1 or induce target internalization. Passive transfer experiments revealed that IgG4 antibodies targeted Nfasc155 on Schwann cell surfaces, and diminished Nfasc155 protein levels and prevented paranodal complex formation in neonatal animals. In adult animals, chronic intrathecal infusions of antibodies also induced the loss of Nfasc155 and of paranodal specialization and resulted in conduction alterations in motor nerves. These results indicate that anti-Nfasc155 IgG4 antibodies perturb conduction in the absence of demyelination, validating the existence of paranodopathy. These results also shed light on the mechanisms regulating protein insertion at paranodes.

Authors

Constance Manso, Luis Querol, Cinta Lleixà, Mallory Poncelet, Mourad Mekaouche, Jean-Michel Vallat, Isabel Illa, Jérôme J. Devaux

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Figure 1

Antibodies to Nfasc155 do not alter the interaction between Nfasc155 and its axonal partners CNTN1 and CASPR1.

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Antibodies to Nfasc155 do not alter the interaction between Nfasc155 and...
(A–C) For aggregation assays, HEK293 cells were cotransfected with mCherry-tagged Nfasc155 or with GFP-tagged CASPR1 and CNTN1. Cells were then incubated under gentle agitation for 2 hours in the presence of 10 μg of control IgG4, anti-CNTN1 IgG4, or anti-Nfasc155 IgG4 from 3 patients (CIDP1–3). As negative controls, Nfasc155-expressing HEK293 cells were incubated with cells expressing GFP alone (top left panel). Cells were examined with a fluorescence microscope at ×10 objective. Representative fields are shown in A (n = 3–4 experiments for each condition). Dashed circles highlight cell aggregates with contacts between red and green cells. The percentage of cell clusters with contacts between green and red cells was quantified (B), as well as the relative frequency of green cells per aggregate (C) (n = 3–4 experiments for each condition). CASPR1/CNTN1– and Nfasc155-expressing cells form clusters. Anti-CNTN1 IgG4 significantly prevented the formation of cell aggregates (**P < 0.005 by unpaired 2-tailed Student’s t tests for 2 samples of equal variance and by 1-way ANOVA followed by Bonferroni’s post hoc tests). By contrast, anti-Nfasc155 IgG4 did not affect the interaction between Nfasc155 and CASPR1/CNTN1. Bars represent mean and SEM. Scale bar: 50 μm.