Purpose: Polyamines are ubiquitous polycationic molecules found in all mammalian cells. They are involved in the regulation of cellular proliferation and levels are elevated in tissues undergoing more rapid proliferation, such as in cancer cells. In early osteoarthritis (OA) there is increased proliferation as a response to damage repair. Therefore polyamines could be a useful marker of this increased proliferation and OA progression. The purpose of this study was to determine whether there were differences in polyamine concentrations in a cohort of volunteers with various radiographic grades of hip or knee OA. Methods: Polyamine concentrations were determined by LC-MS/MS using a benzoyl chloride derivatisation method from plasma samples (n=57 knee & n=30 hip). Kellgren-Lawrence grade (KLG) was assessed from radiographs by a single clinician. OA severity groups were determined by KLG groupings (KLG=0, both knees/hips or KLG=1 in one knee/hip & KLG=0 for contralateral knee/hip; no OA; KLG=1 in both knees/hips, mild OA; KLG=2, moderate OA; KLG=3-4 severe OA). Radiographic OA (ROA) was defined as KLG ≥2. Plasma concentrations of plasma analytes were tested using one-way ANCOVA, weighted for OA severity with polynomial contrasts and adjusted for age & BMI. Analysis of ROA v no ROA was analysed using independent sample t-tests. All tests were performed using SPSS v22.0. Results: Our data show that the determination of plasma polyamine concentrations is reliable with intra-assay variation % RSD calculated to be 9.6 (Putrescine; PUT), 7.2 (Spermidine; SPD), 8.4 (Spermine; SPM) and the inter-assay variation was 8.7 (PUT), 7.9 (SPD) & 9.6 (SPM). Analysis of the polyamines in plasma by two way ANCOVA for joint affected and OA severity filtered to exclude the no OA group, showed that there was a statistically significant interaction for PUT concentrations between severity and the joint affected (P=0.015 unadjusted P=0.018 adjusted; Fig 1 a & b). No interactions were determined for SPD, SPM or the total polyamine concentration. There was no difference observed between ROA and no ROA for any of the polyamines or the total polyamine concentration (PUT P=0.801, SPD P=0.838, SPM P= 0.853, total polyamine concentration P=0.795). Conclusions: This pilot study indicated that measurement of polyamine concentrations in plasma of volunteers with osteoarthritis is reproducible. Few studies investigating polyamine concentrations in OA have been performed previously and ours is the first study to utilise plasma samples to determine systemic plasma concentrations in OA. Our data suggest that there are a number of different OA phenotypes, particularly highlighted by the differences between hip and knee OA. Further study of polyamine concentrations in OA needs to be carried out with larger numbers of patients.
|Number of pages||2|
|Journal||Osteoarthritis and Cartilage|
|Issue number||Supplement 2|
|Publication status||Published - Apr 2015|
|Event||World Congress of the Osteoarthritis-Research-Society-International (OARSI) on Osteoarthritis 2015 - Seattle, Seattle, United States|
Duration: 30 Apr 2015 → 3 May 2015