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. 2015 Mar 19:5:9259.
doi: 10.1038/srep09259.

Biomarkers of early stage osteoarthritis, rheumatoid arthritis and musculoskeletal health

Usman Ahmed  1 , Attia Anwar  1 , Richard S Savage  2 , Matthew L Costa  3 , Nicola Mackay  1 , Andrew Filer  4 , Karim Raza  4 , Richard A Watts  5 , Paul G Winyard  6 , Joanna Tarr  6 , Richard C Haigh  7 , Paul J Thornalley  2 , Naila Rabbani  2
Affiliations

Biomarkers of early stage osteoarthritis, rheumatoid arthritis and musculoskeletal health

Usman Ahmed et al. Sci Rep. .

Abstract

There is currently no biochemical test for detection of early-stage osteoarthritis (eOA). Tests for early-stage rheumatoid arthritis (eRA) such as rheumatoid factor (RF) and anti-cyclic citrullinated peptide (CCP) antibodies require refinement to improve clinical utility. We developed robust mass spectrometric methods to quantify citrullinated protein (CP) and free hydroxyproline in body fluids. We detected CP in the plasma of healthy subjects and surprisingly found that CP was increased in both patients with eOA and eRA whereas anti-CCP antibodies were predominantly present in eRA. A 4-class diagnostic algorithm combining plasma/serum CP, anti-CCP antibody and hydroxyproline applied to a cohort gave specific and sensitive detection and discrimination of eOA, eRA, other non-RA inflammatory joint diseases and good skeletal health. This provides a first-in-class plasma/serum-based biochemical assay for diagnosis and type discrimination of early-stage arthritis to facilitate improved treatment and patient outcomes, exploiting citrullinated protein and related differential autoimmunity.

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Conflict of interest statement

No authors have any competing interests apart from U.A., R.S., P.J.T. and N.R., they published a patent on this work (international publication number: WO2014016584).

Figures

Figure 1
Figure 1
(a) Formation of citrullinated protein. (b) Analysis of citrullinated protein. Detection and quantitation of citrulline by stable isotopic dilution analysis LC-MS/MS. Left-hand panel – MRM chromatogram of citrulline in plasma protein digest from patient with eOA, middle panel - MRM chromatogram of [5-13C-4,4,5,5-2H4]citrulline internal standard (5 pmol), right-hand panel – calibration curve of citrulline/[5-13C-4,4,5,5-2H4]citrulline MRM chromatographic peak area ratio against citrulline standard (pmol). (c) Citrullinated protein (CP) and (d) hydroxyproline (Hyp) in early-stage arthritis and healthy human subjects. Samples were plasma for Control (n = 16) and eOA (n = 16) and serum for eRA (n = 10) and non-RA (n = 10). Significance: *, ** and ***, P < 0.05, P < 0.01 and P < 0.001 with respect to control (healthy people). Data are median (lower – upper quartile). (e) Discrimination of study groups by discrete patterns of CP, Hyp and Anti-CCP antibody response. Each darkened shade presents approximately a 2-fold increase.
Figure 2
Figure 2. Training and validation of a multiclass algorithm for detection and discrimination of early stage osteoarthritis, rheumatoid arthritis, other inflammatory joint disease from healthy subjects.
(a) Training set and test set study groups. Receiver operating characteristic curves in the test set for detection of: (b) healthy controls (n = 37), (c) eOA (n = 30), (d) eRA (n = 35) and (e) non-RA (n = 32).
Figure 3
Figure 3. Citrullinated protein and hydroxyproline in plasma and synovial fluid compartments in early-stage and advanced arthritis.
CP: (a) osteoarthritis and (b) rheumatoid arthritis. Hyp: (c) osteoarthritis and (d) rheumatoid arthritis. Data are median (lower – upper quartile); for eOA, n = 16; aOA, n = 17, eRA, n = 10 and aRA, n = 22. Lines joint median estimates in plasma/serum to synovial fluid from the same subject groups.
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References

    1. Connelly L. B., Woolf A. & Brooks P. [Cost-effectiveness of interventions for musculoskeletal conditions]. Disease Control Priorities in Developing Countries [Jamieson, D. T. et al. (eds.)] [963–980] (World Bank, Washington DC, 2006). - PubMed
    1. Menashe L. et al. The diagnostic performance of MRI in osteoarthritis: a systematic review and meta-analysis. Osteoarthritis & Cartilage 20, 13–21 (2012). - PMC - PubMed
    1. Raza K. et al. Predictive value of antibodies to cyclic citrullinated peptide in patients with very early inflammatory arthritis. J. Rheumatol. 32, 231–238 (2005). - PMC - PubMed
    1. Van Venrooij W. J., Van Beers J. J. B. C. & Pruijn G. J. M. Anti-CCP antibody, a marker for the early detection of rheumatoid arthritis. Ann. N.Y. Acad. Sci. 1143, 268–285 (2008). - PubMed
    1. Van Venrooij W. J., van Beers J. J. B. C. & Pruijn G. J. M. Anti-CCP antibodies: the past, the present and the future. Nature Rev. Rheumatol. 7, 391–398 (2011). - PubMed

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