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Objective. IgG aPL against domain I of β2-glycoprotein I (β2GPI) [anti-DI (aDI)] is associated with the pathogenesis of APS, an autoimmune disease defined by thrombosis and pregnancy morbidity. To date, however, no study has demonstrated direct pathogenicity of IgG aDI in vivo. In this proof-of-concept study, we designed a novel system to affinity purify polyclonal aDI aPL in order to assess its prothrombotic ability in a well-characterized mouse microcirculation model for APS. Methods. Two polyclonal IgG fractions were isolated from serum of a patient with APS, both with high aPL activity but differing in aDI activity (aDI-rich and aDI-poor). These IgG fractions were tested for their pathogenic ability in an in vivo mouse model of thrombosis. Male CD1 mice were injected intraperitoneally with either aDIrich or aDI-poor IgG; as a control, IgG isolated from healthy serum was used. A pinch injury was applied to the right femoral vein and thrombus dynamics and tissue factor activity in isolated tissue were evaluated. Results. Both aDI-rich and aDI-poor IgG retained aCL and anti-β2GPI activity, while only aDI-rich IgG displayed high aDI activity, as defined by our in-house cut-offs for positivity in each assay. aDI-rich IgG induced significantly larger thrombi in vivo compared with aDI-poor IgG (P<0.0001). Similarly, aDI-rich IgG significantly enhanced the procoagulant activity of carotid artery endothelium and peritoneal macrophages isolated from experimental animals (P<0.01). Conclusion. These data directly demonstrate that the ability to cause thrombosis in vivo is concentrated in the aDI fraction of aPL. [ABSTRACT FROM AUTHOR]

Objectives. Spleen tyrosine kinase (SYK) is a core signalling protein that drives inflammatory responses and is fundamental to the propagation of signals via numerous immune receptors, including the B cell receptor and Fc receptors (FcRs). Fostamatinib, a small molecule SYK inhibitor, has shown evidence of ameliorating inflammation in RA patients. We sought to understand how the active metabolite of fostamatinib, R406, affects the inflammatory response at the cellular level.Methods. Antigen-specific in vivo systems and in vitro fluorescence microscopy were combined to investigate the effects of fostamatinib on antigen-specific interactions between dendritic cells (DCs) and CD4+ T cells.Results. Although it has previously been shown that R406 reduces the response of DCs to immune complexes (ICs), we found that fostamatinib failed to reduce specific CD4+ T cell proliferation in mice after immunization with ICs. However, we observed in vitro that R406 reduces both the area and duration of cellular interactions between IC-activated DCs and specific CD4+ T cells during the initial phase of cellular crosstalk. This led to diminished proliferation of antigen-specific CD4+ T cells after R406 treatment compared with vehicle controls. This decreased proliferative capacity of CD4+ T cells was accompanied by reduced expression of the co-stimulatory molecules, inducible T cell co-stimulator (ICOS) and PD-1, and abrogation of the production of inflammatory cytokines such as IFN-γ and IL-17.Conclusion. Our findings indicate a potential mechanism by which this compound may be effective in inhibiting FcR-driven CD4+ T cell responses. [ABSTRACT FROM PUBLISHER]

Objective. Granulomatosis with polyangiitis (GPA) is a rare and sometimes fatal systemic autoimmune disease. ANCAs specific for PR3 are associated with GPA. Remission in GPA can be achieved through B cell depletion (BCD) therapy. Our aim was to understand whether the frequencies of T cell subsets are influenced by BCD.Methods. The frequencies of circulating T follicular helper cells (cTFHs) and regulatory T cells (Tregs) from 36 GPA patients including 11 rituximab-treated patients and 10 healthy controls were studied by flow cytometry. The functional capacity of Tregs was assessed by in vitro co-culture assays.Results. We observed an increased frequency of cTFHs and a reduced frequency of antigen-experienced Tregs in peripheral blood from GPA patients on conventional therapies but not in those treated with rituximab compared with healthy controls. Furthermore, the ratio of cTFHs to Tregs was significantly higher in GPA patients on conventional therapies than in GPA patients treated with rituximab who were clinically improved or controls. Whereas Tregs were numerically reduced in GPA patients on conventional therapy, the suppressive capacity of Tregs on a per cell basis was not significantly altered in these individuals.Conclusion. Our study illustrated increased cTFHs with decreased antigen-experienced Tregs in GPA patients on conventional therapies, but in B cell-depleted patients the levels of cTFHs and Tregs were similar to healthy controls. The negative correlation between cTFHs and Tregs implies the balance between T cell subsets and its B cell dependence impact on disease activity in GPA. [ABSTRACT FROM PUBLISHER]

Objective. To describe the effect of customized foot orthoses (FOs) on the kinematic, kinetic and EMG features in patients with RA, tibialis posterior (TP) tenosynovitis and associated pes plano valgus.Methods. Patients with RA and US-confirmed tenosynovitis of TP underwent gait analysis, including three-dimensional (3D) kinematics, kinetics, intramuscular EMG of TP and surface EMG of tibialis anterior, peroneus longus, soleus and medial gastrocnemius. Findings were compared between barefoot and shod with customized FO conditions.Results. Ten patients with RA with a median (range) disease duration of 3 (1–18) years were recruited. Moderate levels of foot pain and foot-related impairment and disability were present with moderately active disease states. Altered timing of the soleus (P = 0.05) and medial gastrocnemius (P = 0.02) and increased magnitude of tibialis anterior (P = 0.03) were noted when barefoot was compared with shod with FO. Trends were noted for reduced TP activity in the contact period (P = 0.09), but this did not achieve statistical significance. Differences in foot motion characteristics were recorded for peak rearfoot eversion (P = 0.01), peak rearfoot plantarflexion (P < 0.001) and peak forefoot abduction (P = 0.02) in the shod with FOs compared with barefoot conditions. No differences in kinetic variables were recorded.Conclusion. This study has demonstrated, for the first time, alterations in muscle activation profiles and foot motion characteristics in patients with RA, pes plano valgus and US-confirmed TP tenosynovitis in response to customized FOs. Complex adaptations were evident in this cohort and further work is required to determine whether these functional alterations lead to improvements in patient symptoms. [ABSTRACT FROM PUBLISHER]

Objectives. HLA-B*27:05 is associated with AS whereas HLA-B*27:09 is not associated. We hypothesized that different interactions with KIR immune receptors could contribute to the difference in disease association between HLA-B*27:05 and HLAB*27:09. Thus, the objective of this study was to compare the formation of β2m-free heavy chain (FHC) including B27 dimers (B272) by HLA-B*27:05 and HLA-B*27:09 and their binding to KIR immunoreceptors.Methods. We studied the formation of HLA-B*27:05 and HLA-B*27:09 heterotrimers and FHC forms including dimers in vitro and in transfected cells. We investigated HLA-B*27:05 and HLA-B*27:09 binding to KIR3DL1, KIR3DL2 and LILRB2 by FACS staining with class I tetramers and by quantifying interactions with KIR3DL2CD3ɛ-reporter cells and KIR3DL2-expressing NK cells. We also measured KIR expression on peripheral blood NK and CD4 T cells from 18 HLA-B*27:05 AS patients, 8 HLA-B27 negative and 12 HLA-B*27:05+ and HLA-B*27:09+ healthy controls by FACS staining.Results. HLA-B*27:09 formed less B272 and FHC than HLA-B*27:05. HLA-B*27:05-expressing cells stimulated KIR3DL2CD3ɛ-reporter T cells more effectively. Cells expressing HLA-B*27:05 promoted KIR3DL2+ NK cell survival more strongly than HLA-B*27:09. HLA-B*27:05 and HLA-B*27:09 dimer tetramers stained KIR3DL1, KIR3DL2 and LILRB2 equivalently. Increased proportions of NK and CD4 T cells expressed KIR3DL2 in HLA-B*27:05+ AS patients compared with HLA-B*27:05+, HLA-B*27:09+ and HLA-B27− healthy controls.Conclusion. Differences in the formation of FHC ligands for KIR3DL2 by HLA-B*27:05 and HLA-B*27:09 could contribute to the differential association of these alleles with AS. [ABSTRACT FROM PUBLISHER]

Objective. We previously reported the coexistence, within cultured mesenchymal stem cells (MSCs) from human synovial membrane, of single-cell-derived clonal cell populations with distinct differentiation potency. The aim of this study was to investigate marker sets for prospective purification of functionally distinct MSC subsets.Methods. Cells were enzymatically released from human synovium and culture expanded. Phenotype analysis was performed by flow cytometry using combinations of MSC markers. Sorting was carried out using the FACS DiVA cell sorter. Sorted cell populations were assessed for clonogenicity, kinetics of growth, cell senescence and chondro-osteogenic potency.Results. During culture expansion, the co-localization of CD39 within the CD73+ cell population identified a small cell subset that was maintained from passage 1 (P1) up to at least P12 in all donors tested. The CD73+CD39+ cell subset displayed higher expression levels of Sox9 and Runx2 and a significantly greater chondro-osteogenic potency than the CD73+CD39− cell subset. In contrast, it was less clonogenic and proliferative. There was no difference in cell senescence between the sorted MSC subsets and the parental MSCs. Notably, there were no detectable differences in chondro-osteogenic potency between the CD73+CD39− and CD73+CD39+ cell subsets purified from fresh synovial cell populations.Conclusion. Our findings indicate that the combination of CD73 and CD39 allows the prospective purification from culture-expanded heterogeneous synovial MSC populations of a distinct MSC subset with greater chondro-osteogenic potency. We anticipate that such an approach will enhance the consistency of cell-based therapeutic protocols for the repair of osteochondral defects. [ABSTRACT FROM AUTHOR]

Objective. Previously, active shape modelling (ASM) of the proximal femur was shown to identify those individuals at highest risk of developing radiographic OA. Here we determine whether ASM predicts the need for total hip replacement (THR) independent of Kellgren–Lawrence grade (KLG) and other known risk factors.Methods. A retrospective cohort study of 141 subjects consulting primary care with new hip pain was conducted. Pelvic radiographs taken on recruitment were assessed for KLG, centre-edge angle, acetabular depth and femoral head migration. Clinical factors (duration of pain, use of a stick and physical function) were collected by self-completed questionnaires. ASM differences between shape mode scores at baseline for individuals who underwent THR during the 5-year follow-up (n = 27) and those whose OA did not progress radiographically (n = 75) were compared.Results. A 1 s.d. reduction in baseline ASM mode 2 score was associated with an 81% reduction in odds of THR (OR = 0.19, 95% CI 0.52, 0.70) after adjustment for KLG, radiographic and clinical factors. A similar reduction in odds of THR was associated with a 1 s.d. reduction in mode 3 (OR = 0.45, 95% CI 0.28, 0.71) and a 1 s.d. increase in mode 4 score (OR = 2.8, 95% CI 1.7, 4.7), although these associations were no longer significant after adjustment for KLG and clinical factors.Conclusion. ASM of the hip joint is a reliable early biomarker of radiographic OA severity, which can improve the ability to identify patients at higher risk of rapid progression and poor outcome even when KLG and clinical risk factors are taken into account. [ABSTRACT FROM PUBLISHER]

Objectives. Behçet’s disease (BD) is more severe among young males and disease severity decreases with age. Therefore, the effect of disease activity, gender and age on platelet and neutrophil activation in whole blood taken from patients with BD was investigated.Methods. Using an anti-coagulant Tripotassium ethylenediaminetetra acetic acid (K3EDTA) plus citrate-theophylline-adenosine-dipyridamole (CTAD) (K3EDTA/CTAD) that preserves the degree of platelet activation that exists in vivo, we assessed neutrophil and platelet activation, microparticles, and monocyte and neutrophil–platelet aggregate formation in 43 BD patients using flow cytometry. This is the first description of platelet activation and microparticles in BD patients using this methodology.Results. Inactive [2.78 (0.56)%, P = 0.0009; 3.11 (0.78)%, P < 0.0001] and active [2.28 (0.84)%, P < 0.0001; 3.071 (0.67)%, P = 0.0031] BD patients had significantly higher percentages of CD62P-expressing platelets and CD62P+ platelet microparticles as compared with healthy controls (HCs) [0.84 (0.1)% and 1.23 (0.14)%], respectively. The percentages of CD62P+ platelets and CD62P+ platelet microparticles in female and male BD patients were also significantly higher than those expressed by female and male HCs. The percentages of CD62P+ microparticles were significantly increased in the 20–30-(P = 0.0301) and 31–50-(P < 0.0162) year age ranges, but not in the >50-year age group of BD patients.Conclusion. BD is a rare, chronic multi-systemic vasculitis and interaction of activated platelets with leucocytes has been linked to pathological disorders associated with vascular inflammation. Importantly, this study demonstrates that platelet microparticle activation is increased in BD. Also, this is the first report in which changes in platelet activation in BD are concordant with the observations that BD disease activity diminishes with age. [ABSTRACT FROM PUBLISHER]

Objective. Echocardiography is widely used in the investigation of patients with suspected SSc-associated pulmonary arterial hypertension (SSc-PAH). We investigated whether CT pulmonary angiography (CTPA) provides additive diagnostic value.Methods. Data for 89 consecutive patients with suspected SSc-PAH undergoing echocardiography, CTPA and right heart catheterization were reviewed. Pulmonary artery diameter (dPA) and ascending aorta diameter (dAA), right and left ventricular diameter (dRV and dLV) and grade of tricuspid regurgitation (TRCT) measured at CTPA and tricuspid gradient (TGECHO) at echocardiography were retrieved. A predictive equation for mean pulmonary arterial pressure (mPAP) was derived using multivariate linear regression. Multivariate Cox regression analysis was then used to assess the prognostic strength of CTPA parameters and TGECHO.Results. Absolute measures of dPA and dRV correlated weakly with mPAP. However, dPA : dAA and dRV : dLV showed stronger correlations with mPAP (dPA : dAA r = 0.42, P < 0.001; dRV : dLV r = 0.51, P < 0.001). dRV : dLV correlated more strongly with pulmonary vascular resistance than did dPA : dAA (r = 0.63 vs 0.39, P both <0.001). dPA : dAA and TGECHO were independent predictors of mPAP. A derived CT/echo composite index had a higher predictive accuracy (area under the curve = 0.95) than dPA : dAA or TGECHO although negative predictive value (NPV) was only 77%. Combining the CT/echo composite index with presence or absence of TRCT increased NPV to 100% although this observation requires further validation. dRV : dLV was the strongest prognostic factor.Conclusion. In suspected SSc-PAH, cardiac chamber and great vessel measurements at CTPA correlate with pulmonary haemodynamics and predict survival. In combination with echocardiography CTPA increases diagnostic accuracy and may identify other potential causes of breathlessness. [ABSTRACT FROM PUBLISHER]

Objective. Since 2000, we have given B-cell depletion therapy (BCDT) with rituximab to 76 patients with active SLE refractory to standard immunosuppression. Twenty-four of these patients have now received repeated cycles of BCDT. The aims of the study were to: (i) assess the efficacy and safety of repeated cycles of BCDT in treating refractory SLE; and (ii) assess whether retreatment produced a more sustained clinical response.Methods. BCDT was administered using CYC 750 mg, methylprednisolone 125–250 mg and rituximab 1 g given intravenously on two occasions, 2 weeks apart. Patients were reviewed at 1–2 monthly intervals and disease activity assessed using the BILAG activity index and serological markers. Clinical response was categorized as complete or partial remission, or no response, based on the change in BILAG scores.Results. Eighteen patients had sufficient data for detailed analysis. All were female; mean age 29.9 years; mean duration of follow-up 58.7 months. Two patients died during follow-up and there were two infusion reactions. Disease activity was significantly reduced after both cycles of BCDT at 6 months. More patients achieved disease remission after the second cycle (82 vs 61% first cycle), which was maintained in 65% at 12 months (vs 39% first cycle). The time to disease flare was significantly longer after the second cycle (P < 0.001) and 33% of our patients have still not flared to date following retreatment (mean follow-up 24.5 months).Conclusion. Repeated cycles of BCDT with rituximab are effective in treating refractory SLE and has a favourable safety profile. Retreatment may produce a more sustained clinical response. [ABSTRACT FROM PUBLISHER]