Objective To investigate the morphological features of chronic inflammatory demyelinating polyneuropathy (CIDP) with autoantibodies directed against paranodal junctional molecules, particularly focusing on the fine structures of the paranodes.
Methods We assessed sural nerve biopsy specimens obtained from 9 patients with CIDP with anti-neurofascin-155 antibodies and 1 patient with anti-contactin-1 antibodies. 13 patients with CIDP without these antibodies were also examined to compare pathological findings.
Results Characteristic light and electron microscopy findings in transverse sections from patients with anti-neurofascin-155 and anti-contactin-1 antibodies indicated a slight reduction in myelinated fibre density, with scattered myelin ovoids, and the absence of macrophage-mediated demyelination or onion bulbs. Teased-fibre preparations revealed that segmental demyelination tended to be found in patients with relatively higher frequencies of axonal degeneration and was tandemly found at consecutive nodes of Ranvier in a single fibre. Assessment of longitudinal sections by electron microscopy revealed that detachment of terminal myelin loops from the axolemma was frequently found at the paranode in patients with anti-neurofascin-155 and anti-contactin-1 antibody-positive CIDP compared with patients with antibody-negative CIDP. Patients with anti-neurofascin-155 antibodies showed a positive correlation between the frequencies of axo–glial detachment at the paranode and axonal degeneration, as assessed by teased-fibre preparations (p<0.05).
Conclusions Paranodal dissection without classical macrophage-mediated demyelination is the characteristic feature of patients with CIDP with autoantibodies to paranodal axo–glial junctional molecules.
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Correction notice Since this paper was first published online the terms anticontactin and antineurofascin now read anti-contactin and anti-neurofascin.
Contributors HK and GS developed the hypotheses and conceived the study. HK, SI, YK, MI, DK, NM, MK and GS compiled and analysed the clinical data. MK and KK determined anti-neurofascin-155 and anti-contactin-1 antibodies; HO, RY and JK verified the results. HK, SI, YK, MI and GS performed the pathological analysis. GS supervised the study. HK wrote the first draft and all authors critically evaluated the manuscript.
Funding This work was supported by grants from the Ministry of Health, Labour and Welfare (Research on rare and intractable diseases, H26-057) and the Ministry of Education, Culture, Sports, Science and Technology (25461276) of Japan.
Competing interests None declared.
Patient consent Obtained.
Ethics approval Ethics Committees of Nagoya University Graduate School of Medicine, National Defense Medical College and Kyushu University.
Provenance and peer review Not commissioned; externally peer reviewed.