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THU0391 Axial Disease in Psoriatic Arthritis () Study: Serum-Soluble Bone-Turnover Biomarkers of Psoriatic Arthritis Phenotypes
  1. D. Jadon1,2,
  2. R. Sengupta1,
  3. A. Nightingale3,
  4. M. Lindsay3,
  5. H. Lu3,
  6. A. Jobling3,
  7. J. Dunphy1,
  8. E. Korendowych1,
  9. J.T. Elder4,
  10. R.P. Nair4,
  11. G. Shaddick3,
  12. N.J. McHugh1
  1. 1Rheumatology, Royal National Hospital for Rheumatic Diseases, Bath
  2. 2Rheumatology, Addenbrooke's Hospital, Cambridge
  3. 3Pharmacy and Pharmacology, University of Bath, Bath, United Kingdom
  4. 4Medicine, University of Michigan, Ann Arbor, United States

Abstract

Background Psoriatic spondyloarthritis (PsSpA), peripheral-only psoriatic arthritis (pPsA) and ankylosing spondylitis (AS) are characterised by differing patterns of osteoproliferation and bone resorption, which may be reflected by levels of serum-soluble bone-turnover biomarkers.

Objectives To investigate four such potential biomarkers (Dkk-1, M-CSF, MMP-3 and OPG) as predictors of: (i) PsSpA occurrence; (ii) axial radiographic severity; (iii) psoriatic arthritis mutilans (PAM) occurrence.

Methods A prospective single-centre cross-sectional study (ADIPSA) recruited pPsA (n=127; fulfilling CASPAR criteria), PsSpA (n=118; psoriasis with radiographic sacroiliitis and/or spondylitis) and AS (n=157; fulfilling modified New York criteria) cases, and assessed them clinically, radiographically, and in terms of serum biomarkers. Serum was obtained from two other centres of clinically characterised psoriasis-only (PsC; n=200) cases, and sex/age-matched healthy controls (HC; n=50). ELISA was used to measure serum Dkk-1, M-CSF, MMP-3 and OPG concentrations. Multivariable regression analyses compared serum concentrations across disease groups.

Results OPG is a biomarker of axial disease in spondyloarthritis (SpA) cases; concentrations were significantly lower in SpA cases with axial disease (RAD) than in those without (non-RAD) (adjusted odds ratio, ORadj 0.20 per ng/ml increase in concentration; 95%CI 0.05, 0.80; p=0.02), independently of having psoriasis.

Dkk-1 is a biomarker of axial disease in SpA cases, with a pattern for increasing concentration along a spectrum of increasing axial involvement. Dkk-1 concentrations were significantly higher in SpA cases with axial disease than in those without (ORadj 1.22; 95%CI 1.05, 1.42; p=0.01), independently of having psoriasis, and significantly lower in PsSpA than AS cases (ORadj 0.85; 95%CI 0.74, 0.98; p=0.02).

M-CSF is a biomarker of arthritis. Compared with HC, M-CSF concentrations were significantly lower in pPsA (ORadj 0.14; 95%CI 0.06, 0.32; p<1x10–5), PsSpA (ORadj 0.07; 95%CI 0.03, 0.17; p<1x10–8), and AS (ORadj 0.37; 95%CI 0.16, 0.85; p<1x10–7). Similarly, M-CSF concentrations were significantly lower in PsA than PsC cases (ORadj 0.44; 95%CI 0.24, 0.82; p=0.01).

MMP-3 is a biomarker of arthritis. Compared with HC, MMP-3 concentrations were significantly higher in pPsA (ORadj 1.06; 95%CI 1.01, 1.10; p=0.02), PsSpA (ORadj 1.06; 95%CI 1.01, 1.11; p=0.02), and AS (ORadj 1.06; 95%CI 1.01, 1.11; p=0.01). Similarly, MMP-3 concentrations were significantly higher in PsA than PsC cases (ORadj 1.02; 95%CI 1.01, 1.03; p=0.0004).

There were no significant associations between biomarkers and either morphology or radiographic severity (mSASSS or PASRI).

Biomarker levels were no different in PsA cases with/without PAM.

Conclusions OPG and Dkk-1 appear to be biomarkers of axial disease in SpA patients (pPsA, PsSpA, AS), independently of cutaneous psoriasis status. M-CSF and MMP-3 appear to be biomarkers of arthritis, but don't differentiate SpA phenotypes. No biomarkers for PAM occurrence in PsA were found. The high concentration of Dkk-1 in AS and PsSpA, supports previous evidence that Dkk-1 is dysfunctional in axial SpA.

Disclosure of Interest None declared

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