BackgroundThe efficacy of corticosteroids in patients with psoriatic arthritis (PsA) and inflammatory back pain has not been studied to date. In this controlled trial, we aimed to investigate the comparative performance of corticosteroids in patients with active axial-PsA (AxPsA) versus those with active ankylosing spondylitis (AS).MethodsPatients with AxPsA and AS (naïve to biologic therapies), who not only had clinically active disease, but also had bone marrow oedema on magnetic resonance imaging of the sacroiliac joints, were recruited. Clinically active disease was defined as inflammatory back pain (fulfilling Assessment of Spondyloarthritis International Society (ASAS) expert criteria), with spinal pain score (numerical rating scale 0–10) ≥4 and Bath AS Disease Activity Index (BASDAI) score ≥4 despite taking nonsteroidal anti-inflammatory drugs. Moreover, we recruited a control group of patients with non-inflammatory lower back pain. All patients received a single, intra-muscular dose of depot corticosteroid injection (triamcinolone acetonide 80 mg) at baseline. The intra-muscular corticosteroid option was used to overcome any drug compliance issues. Clinical outcome assessments were made at the following time points: baseline, week 2, and week 4. The primary efficacy end point was mean change in Ankylosing Spondylitis Disease Activity Score (ASDAS) at week 2. Key secondary outcomes were mean change in the BASDAI, Bath Ankylosing Spondylitis Functional Index (BASFI) and Ankylosing Spondylitis Quality of Life (ASQoL) at weeks 2 and 4.ResultsIn total, 40 patients were recruited (15 with AxPsA, 15 with AS, and 10 controls). At week 2 following corticosteroid treatment, patients with AxPsA had significantly greater improvement in the mean ASDAS compared to patients with AS (1.43 ± 0.39 vs. 1.03 ± 0.30, p = 0.004), and also when compared to controls (p < 0.001). At week-4, similar significant trend of ASDAS improvement was seen among AxPsA patients compared to AS patients (1.09 ± 0.32 vs. 0.77 ± 0.27, p = 0.007) and controls (p < 0.001). Similarly, the mean BASDAI, visual analogue scale spinal pain score, ASQoL and BASFI improved significantly among patients with AxPsA compared to patients with AS and controls at week 2 (p < 0.05), with this trend also largely maintained at week 4.ConclusionsAxial inflammation in patients with PsA responds significantly better to corticosteroids than in patients with AS. This furthers the argument and adds to the growing evidence that AxPsA and AS are distinct entities.

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Microparticles are sub-micron, membrane-bound particles released from virtually all cells and which are present in the circulation. In several autoimmune disorders their amount and composition in the circulation is altered. Microparticle surface protein expression has been explored as a differentiating tool in autoimmune disorders where the clinical pictures can overlap. Here, we examine the utility of a novel lipid-based marker—microparticle cholesterol, present in all microparticles regardless of cellular origin—to distinguish between rheumatoid arthritis (RA) and systemic lupus erythematosus (SLE). We first isolated a series of microparticle containing lipoprotein deficient fractions from patient and control plasma. There were no significant differences in the size, structure or protein content of microparticles isolated from each group. Compared to controls, both patient groups contained significantly greater amounts of platelet and endothelial cell-derived microparticles. The cholesterol content of microparticle fractions isolated from RA patients was significantly greater than those from either SLE patients or healthy controls. Our data indicate that circulating non-lipoprotein microparticle cholesterol, which may account for 1–2% of measured cholesterol in patient samples, may represent a novel differentiator of disease, which is independent of cellular origin.

BackgroundCRP and ESR are the most commonly and probably the most studied inflammatory markers among patients with inflammatory arthritis. In contrast to rheumatoid arthritis, however, these markers are raised in less than 50% of people with psoriatic arthritis (PsA). Little is known about the long term significance of elevated inflammatory markers during the course of PsA disease.ObjectivesIn a well characterised PsA cohort with a long term follow up, we examined the association of CRP and ESR over the disease course with demographics, clinical and radiographic features, patient reported outcome measures and the number of comorbid conditions.MethodsA cohort of 283 PsA patients all meeting CASPAR criteria and attending rheumatology clinics were evaluated. All underwent detailed skin and rheumatologic assessments, along with cardiovascular risk factor evaluation. Moreover, we documented the presence/absence of comorbidities using the Charlson Comorbidity Index (CCI). All of these patients had CRP and ESR laboratory values assessed along with the other routine laboratory parameters during the disease course. For each patient, we documented CRP and ESR values at 3 different time points: firstly, at the time of the initial diagnosis; secondly, the highest value of CRP and ESR recorded during the disease course; and thirdly at the time of full assessment for this study. Cumulative inflammation over time was represented by the cumulative averages of CRP (ca-CRP) and ESR (ca-ESR) which were calculated from the AUC (Area Under the Curve) of the 3 documented measurements divided by the total number of months of follow-up. Variables significantly associated at a Bonferroni-corrected p-value were included in the multiple linear regression modelling CRP and ESR.ResultsA total of 283 PsA patients [mean age 54.6±12 years; 52% female; mean PsA duration of 19±9 years; 25% with sacroiliitis; 44.5% with peripheral joint erosions; 60% of patients requiring TNFi for PsA] attended for detailed assessments. The median (IQR) and mean (SD) Ca-CRP was 8.8 (4.6–14.8) and 11.72 (10.52), respectively. The median (IQR) and mean (SD) Ca-ESR was 13.8 (7.8–20.1) and 15.78 (10.46). The variables were also checked for multicollinearity. On multiple linear regression, erosions, sacroileitis, and the CCI were most significantly associated with Ca-CRP (unstandardised coefficient B=6.4, 2.9, 1.05, respectively, p<0.01), when controlled for all other variables in the model [(F=77.6, p<0.001), 72% (R-square)]. There was borderline significant association with the higher number of DMARDs and TNFi used (p=0.09, 0.08, respectively). Moreover, on multiple linear regression analysis, the erosions, extent of joint involvement (oligoarthritis/polyarthritis), number of TNFi used and the CCI were most significantly associated with Ca-ESR (unstandarised coefficient B=3.8, 1.8, 1.8, 0.76, respectively) when controlled for all other variables in the model [(F=130, p<0.001), 77% (R-square)].ConclusionsPsA is a heterogeneous disease with <50% of patients developing r...