Background & Aims

Chronic neuropathic pain (NeP) is a debilitating condition that reduces quality of life 1-4. Underlying mechanisms are not well understood, but astrocytes and microglia are known to play central roles 5,6. When activated, they undergo not only morphological-, but also transcriptional changes 7-10. This may promote a shift in functions that can have both protective and detrimental effects on the surrounding neuroparenchyma 9. Like humans, dogs of the Cavalier King Charles Spaniel (CKCS) breed suffer from syringomyelia (SM) with NeP 11-12. We study pain pathophysiology in spinal cords from CKCS with SM and NeP that are euthanized due to unacceptable quality of life. We have previously reported degenerative changes affecting spinal cord nociceptive pathways 13,14. By examining transcriptomic changes in astrocytes and microglia in spinal cord tissue of affected CKCSs, we aim to identify cellular and molecular mechanisms that contribute to the development and maintenance of NeP.

Methods

Spinal cord tissue from 18 privately owned CKCSs with and without SM: 13 cases from the neurology clinic at Copenhagen University Hospital for Companion Animals, Denmark and five from University of Surrey and University of Cambridge, United Kingdom. Dogs were euthanized due to uncontrollable SM-related pain or non-neurological disease and donated by their owners for postmortem research. NanoString’s Geomx technology and their canine-specific panel were used to explore gene regulations in astrocytes and microglia and to investigate the genes’ potential roles in NeP. To identify astrocytes and microglia, all samples were preliminarily stained with rabbit Alexa Fluor 594-conjugate anti–glial fibrillary acidic protein (GFAP) monoclonal antibody, unconjugated rabbit anti-ionized calcium-binding adaptor molecule 1 (IBA1) polyclonal antibody, Alexa Flour 647-conjugate goat anti-rabbit and polyclonal anti-rabbit immunoglobulin G.

Results

Dogs were classified as: symptomatic and asymptomatic presyrinx (n=1+1), symptomatic and asymptomatic SM (n=11+2) and controls (n=3). The most predominant clinical signs of NeP were vocalization, hypersensitivity to touch, scratching of the neck and shoulder, aggravation of scratching by emotional arousal, and neck pain. Presyrinx was defined as a central canal <2 mm and dorsal horn gray matter edema. SM was defined as a central canal >2 mm with edema and loss of structure to the dorsal horn.
Preliminary results from immunofluorescence staining with GFAP (astrocytic marker) showed increased intensity in the majority of dogs with symptomatic syringomyelia and symptomatic presyrinx, compared to controls.

Conclusions

The final results of the spatial transcriptomic analysis as well as conclusions will be presented at the poster session.

References

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Presenting Author

Tenna Pedersen

Poster Authors

Tenna Pedersen

DVM

Department of Veterinary Clinical Sciences, University of Copenhagen

Lead Author

E-mail

Jørgen Steen Agerholm

DVM

Department of Veterinary Clinical Sciences, University of Copenhagen

Lead Author

E-mail

Clare Rusbridge

BVMS

Department of Clinical Sciences, School of Veterinary Medicine, University of Surrey,

Lead Author

E-mail

Fernando Constantino Casas

MVZ

Department of Veterinary Medicine, University of Cambridge

Lead Author

E-mail

Nanna Finnerup

The Danish Pain Research Center - Department of Clinical Medicine, Aarhus University

Lead Author

E-mail

Mette Berendt

DVM

Department of Veterinary Clinical Sciences, University of Copenhagen

Lead Author

E-mail

Jens Randel Nyengaard

MD

Department of Clinical Medicine - Core Centre for Molecular Morphology, Aarhus University

Lead Author

E-mail

Topics

  • Pain in Special Populations: Non-verbal