Fig. 1

Axial disease progression and treatment regimen. Archetypical features of PGISp axial disease. a A representative image of an inflamed intervertebral disc (IVD) in which inflammatory cells (black arrow head) accumulate around the vertebral joint and invade the IVD space. Part of IVD has been destroyed, but there is still residual IVD tissue evident (asterisk). b H&E and c toluidine blue stained sections showing a representative example of a severely affected vertebral joint in which the IVD is destroyed with clear evidence of cartilage end plate (black arrows) and bone destruction (yellow arrow heads) plus evidence of osteoproliferation (red arrow heads). Scale bars: 200 μm. d Schematic representation of PGISp induction and anti-inflammatory treatment regimen. PGISp mice were treated with vehicle or ETN + PRD started 3 days after the third PG injection (“week 6.5”) and continued either until the end of week 8 (short-term) or week 12 (long-term) post-priming. Tissues were harvested at the end of each treatment period. Blue arrows indicate the initiation of treatment. Red arrows indicate tissue harvests. Open arrows indicate the treatment period