Autoantibodies Sensitize Aβ Mechanoreceptors in Fibromyalgia Sensory Disturbances

Overview

Recent research implicates autoantibodies targeting peripheral nerves in fibromyalgia, contributing to sensory abnormalities such as heightened touch and cold sensitivity. Patient IgG transferred to mice induces hypersensitivity in large-diameter Aβ mechanoreceptors, correlating with clinical symptoms including paraesthesia and dysaesthesia.

Background

Fibromyalgia is a complex syndrome characterized by widespread pain and sensory hypersensitivities, with both central and peripheral nervous system involvement. Approximately 40%–50% of patients exhibit small fibre pathology, and emerging evidence suggests immune mechanisms, particularly autoantibodies, play a role. These autoantibodies target dorsal root ganglia neurons and satellite glia, altering nociceptor excitability and contributing to symptom severity. Understanding these mechanisms is critical given the limited efficacy of current treatments.

Data Highlights

Key findings from patient cohorts and mouse models include:

Key Findings

• Autoantibodies from fibromyalgia patients induce mechanical and cold hypersensitivity when transferred to mice.
• Aβ mechanoreceptors, particularly rapidly adapting (RA) and slowly adapting (SA) fibres, show sensitization with reduced thresholds and increased firing rates.
• A subset of Aβ SA fibres acquire abnormal cold sensitivity post-IgG treatment, correlating with patient-reported paraesthesia.
• In vivo calcium imaging reveals increased cold responses in large-diameter DRG neurons in IgG-treated mice, indicating heterogeneity in IgG effects.
• Microneurography in patients confirms altered Aβ SA fibre responsiveness to cooling, supporting translational relevance.
• Patient symptom severity correlates with autoantibody binding intensity and sensory abnormalities, including temperature sensitivity and unpleasant sensations.

Clinical Implications

Recognition of autoantibody-mediated sensitization of large-diameter mechanoreceptors expands the understanding of fibromyalgia pathophysiology beyond central mechanisms. This insight highlights potential targets for immunomodulatory therapies, such as plasma exchange, which may alleviate sensory symptoms. Clinicians should consider peripheral immune contributions when evaluating and managing fibromyalgia patients with prominent sensory disturbances.

Conclusion

The involvement of autoantibodies in sensitizing Aβ mechanoreceptors provides a novel mechanistic link to sensory abnormalities in fibromyalgia. These findings pave the way for targeted interventions addressing peripheral immune-nervous system interactions in this challenging condition.

References

1. Israel et al. 2022 -- Aβ low threshold mechanoreceptors contribute to sensory abnormalities in fibromyalgia