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Immunopathological features of myopathy associated with small-to-medium-sized vessel vasculitis and differences from autoimmune myositis
S. Nomura1, Y. Shimojima2, T. Ichikawa3, D. Miyazaki4, A. Uruha5, D. Kishida6, Y. Sekijima7
- Department of Medicine (Neurology and Rheumatology), Shinshu University School of Medicine, Matsumoto, Japan.
- Department of Medicine (Neurology and Rheumatology), Shinshu University School of Medicine, Matsumoto, Japan. yshimoji@shinshu-u.ac.jp
- Department of Medicine (Neurology and Rheumatology), Shinshu University School of Medicine, Matsumoto, Japan.
- Department of Medicine (Neurology and Rheumatology), Shinshu University School of Medicine, Matsumoto, Japan.
- Department of Neurology, Tokyo Metropolitan Neurological Hospital, Tokyo, Japan.
- Department of Medicine (Neurology and Rheumatology), Shinshu University School of Medicine, Matsumoto, Japan.
- Department of Medicine (Neurology and Rheumatology), Shinshu University School of Medicine, Matsumoto, Japan.
CER16743
2024 Vol.42, N°4
PI 0786, PF 0794
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PMID: 37706291 [PubMed]
Received: 09/04/2023
Accepted : 19/06/2023
In Press: 14/09/2023
Published: 29/04/2024
Abstract
OBJECTIVES:
Patients with systemic vasculitis may develop myalgia as an initial symptom. However, the immunopathology of vasculitic myopathy remains unclear. We investigated the immunopathological features of skeletal muscle in small-to-medium-sized vessel vasculitis.
METHODS:
We analysed muscle tissue biopsies from 15 patients with vasculitis, including antineutrophil cytoplasmic antibodyassociated vasculitis and polyarteritis nodosa, and 15 patients with autoimmune myositis (AIM), including polymyositis and immune-mediated necrotising myopathy, as comparison disease controls. Immunohistochemical staining for CD56/neural cell adhesion molecule (NCAM), major histocompatibility complex class I, C5b-9/membrane attack complex (MAC), and CD31 was performed. The vascularity score was defined as the total number of CD31-expressing blood vessels. The association between CD56/NCAM-expressing myofibers and clinical findings was evaluated in patients with vasculitis.
RESULTS:
Patients with vasculitis had a significantly lower frequency of CD56/NCAM-expressing myofibers than those with AIM and a positive correlation between the frequency of CD56/NCAM-expressing myofibers and serum aldolase levels. Patients with vasculitis had significantly fewer major histocompatibility complex class I-expressing myofibers and C5b-9/MAC deposits on the sarcolemma than those with AIM. C5b-9/MAC deposits in blood vessels were observed in >70% of patients with vasculitis. Patients with vasculitis had significantly higher vascularity scores in the endomysium than those with AIM.
CONCLUSIONS:
Patients with vasculitis demonstrated mild myofiber damage based on the lower involvement of CD56/NCAM-expressing myofibers compared to those with AIM. Complement component deposits on the vessel walls and hypervascularity in the endomysium areas may be immunopathological features of vasculitic myopathy.
