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 3

Passive transfer of anti-Nfasc155 IgG4 affects the formation of paranodal axoglial unit during development.

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Passive transfer of anti-Nfasc155 IgG4 affects the formation of paranoda...
(A–D) Newborn rat pups received an i.p. injection of 250 μg of control IgG4 (A) or anti-Nfasc155 IgG4 from patient CIDP1 (B) on the day of birth (n = 4 animals for each condition and age). Sciatic nerve fibers were fixed and immunolabeled for voltage-gated sodium channels (Nav; green) and CASPR1 (red) at postnatal days 0 (P0), 2, 4, and 6. The percentages of Nav clusters with 1 or 2 flanking CASPR1-positive paranodes (double arrowheads) or without CASPR1-positive paranodes (arrowheads) were quantified at each age (C), as well as the paranodal length (D) (n = 200–300 nodes or paranodes for each condition and age). Injection of anti-Nfasc155 IgG4 importantly delayed the formation of CASPR1-positive paranodes, and a significantly higher percentage of heminodes without flanking paranodes was observed at P2 (**P < 0.005 by 1-way ANOVA followed by Bonferroni’s post hoc tests). Paranodal length was also significantly shorter 2 and 4 days after injection of anti-Nfasc155 IgG4 (*P < 0.05 by 1-way ANOVA followed by Bonferroni’s post hoc tests). Scale bar: 10 μm. (E and F) Sciatic nerve and spinal cord proteins (100 μg) from P2 animals injected with control IgG4 (n = 4) or anti-Nfasc155 IgG4 (n = 4) at P0 were immunoblotted with antibodies recognizing all neurofascin isoforms (Pan-neurofascin) or specifically Nfasc155. The level of Nfasc155 was quantified relatively to that of Nfasc186 in both sciatic nerve and spinal cord (F). Nfasc155 level was significantly decreased in sciatic nerves of animals treated with anti-Nfasc155 IgG4, but not in spinal cord (**P < 0.005 by unpaired 2-tailed Student’s t tests for 2 samples of equal variance). Molecular weight markers are shown on the right (in kilodaltons). Bars represent mean and SEM.