Cutibacterium Acnes Cause Intervertebral Disc Degeneration, However It Is Reversible – a Rabbit in vivo Animal Model

Introduction: Presence of Cutibacterium acnes (C. acnes) and formation of biofilms have been linked to endplate changes and disc degeneration. The aim of the current project was to establish a minimally invasive model of disc degeneration caused by C. acnes and to assess if the treatment with an antibacterial solution (BDS) leads to decreased pro-inflammatory and increased anti-inflammatory cytokine expression as well as restoration of disc degeneration.

Methods: Twelve New Zealand white rabbits were used. Under c-arm guidance, an 18-gauge driver needle was first positioned laterally, and a 29-gauge Hamilton needle was then inserted through the driver needle into the nucleus. 18 µL of 1x108 CFU C. acnes solution was injected. After 8- or 12-weeks animals were imaged again and injected with BDS1, BDS2, or saline. A final MRI was taken on the day of endpoint immediately before euthanasia.

Results: From 36 C. acnes injected levels, 14 levels were degenerated and injected with BDS1 (n=6), BDS2 (n=5), or saline (n=3).
Average disc height decreased over time in all treatment groups and average Pfirrmann grade increased over time in all treatment groups. RT-PCR wound healing array showed following trends: Saline vs. Control – two fold upregulation of pro-inflammatory cytokines and enzymes and downregulation of matrix proteins; BDS1 vs control - two to twelve fold upregulation of pro- and anti-inflammatory cytokines, matrix proteins and enzymes; BDS2 vs control 2.2-fold upregulation of ITGB6 and down-regulation of matrix proteins.

Conclusion : The current pilot study agrees with previously published research that biofilms can initiate disc degeneration and that anti-bacterial biologics have a potential in reducing degenerative cascades. A follow-up study with a larger sample size is planned to determine the extent of BDS1 in disc regeneration.