Table 3 Biomarkers at the bone cartilage interface in RA

Bone turnover

 CTX-I

Conflicting

Correlated with joint damage, radiographic progression and response to treatment

[143,144,145,146]

 ICTP

Increased

Correlated with joint damage

[145, 146]

 C1M

Increased

Correlate with joint damage (JSN, mtss) and radiographic progression

[147] [85]

 Osteocalcin

Reduced (in naïve comparedto healthy controls)

Predictive of treatment response to anti-IL-6R therapy in combination withbiomarkers CTX-I and C2M

[144, 148, 149]

Cartilage Turnover

 CTX-II

Increased

Associated with radiographic progression

[150]

 C2M

–

Low levels associated with anti-Il-6R treatment response by swollen andtender joint count in composite with CTX-I and osteocalcin

[144]

–

 –

 PIIANP

decreased

 –

[151]

Synovium turnover

 C4M

Increased

Associated with anti-IL-6R treatment efficacy. Baseline levels associated withstructural progression by JSN and Sharp score

[152]