Increased synovial galectin-3 induce inflammatory fibroblast activation and osteoclastogenesis in patients with rheumatoid arthritis.

OBJECTIVE: Galectin-3 (Gal-3) has been suggested as a proinflammatory mediator in rheumatoid arthritis (RA). We aimed to study clinical and pathogenic aspects of Gal-3 in RA. METHOD: Plasma samples from healthy controls (n = 48) and patients with newly diagnosed, early RA were assayed for soluble Gal-3. In patients with chronic RA (n = 18), Gal-3 was measured in both plasma and synovial fluid. Synovial fluid mononuclear cells were used to purify fibroblast-like synoviocytes (FLSs) and osteoclasts. Monocultures of FLSs and autologous co-cultures of FLSs and peripheral blood mononuclear cells were established and co-incubated with a Gal-3 inhibitor. RESULTS: Patients with early and chronic RA had persistently increased plasma levels of Gal-3 compared with controls. However, changes in plasma Gal-3 at the level of individuals were associated with long-term disease activity. In seropositive early RA patients, all patients with decreasing plasma Gal-3 from 0 to 3 months had low disease activity after 2 years (p < 0.05). Gal-3 levels in synovial fluid were markedly elevated. In vitro, co-incubation with a Gal-3 inhibitor (GB1107, 10 µM) led to a significant reduction in both interleukin-1ß and tumour necrosis factor-α secretion from FLS monocultures (both p < 0.05) and decreased monocyte-derived osteoclastogenesis compared with controls (both p < 0.05). CONCLUSIONS: Our findings underscore the role of Gal-3 regarding disease activity and tissue destruction in RA. An initial decrease in plasma Gal-3 levels predicted decreased long-term disease activity. Correspondingly, a Gal-3 inhibitor decreased the activity of inflammatory FLSs and osteoclastogenesis in patients with RA.

Baseline serum levels of IgA anti-cyclic citrullinated protein antibodies in early rheumatoid arthritis predict radiographic progression after 11 years of treatment: a secondary analysis of the CIMESTRA study.

OBJECTIVE: Smoking and periodontitis are risk factors for developing rheumatoid arthritis (RA), suggesting a break of tolerance on mucosal surfaces. Immunoglobulin A (IgA) antibodies are part of the mucosal immune system. The dominant autoantibodies in RA are anti-cyclic citrullinated protein antibodies (ACPAs), and IgG and IgA subclasses exist simultaneously. This study aimed to investigate the association of ACPA IgA subtypes with disease activity and long-term radiographic outcomes in RA, compared with ACPA IgG. METHOD: Total ACPA IgG, IgA, IgA1, and IgA2 were quantified in serum from patients with early RA (n = 97). Patient characteristics, IgM rheumatoid factor (IgM-RF) status, clinical and biochemical disease activity scores, and radiographic status evaluated by total Sharp score (TSS), were assessed at baseline and after 2 and 11 years of treatment. RESULTS: All patients with ACPA IgA also had ACPA IgG. ACPA IgA positivity was associated with IgM-RF and male gender. Both ACPA IgA and IgG levels at baseline were weakly associated with disease activity markers. Baseline ACPA IgA and IgG did not show a linear correlation with radiographic status after 10 years, but could predict radiographic progression (ΔTSS ≥ 5 from 0 to 11 years), with positive likelihood ratios of 3.7 and 4.0, respectively. CONCLUSION: ACPA IgA and IgG were weakly associated with disease activity in early RA. RA patients with a ΔTSS ≥ 5 after 11 years of treatment had higher ACPA IgG and ACPA IgA levels at baseline; however, none of the ACPA subtypes was superior in predicting long-term radiographic progression.

Reduced prescription of TNF-inhibitors in chronic arthritis based on therapeutic drug monitoring: A randomized controlled trial.

OBJECTIVE: Dosing of tumour necrosis factor-α inhibitors (TNFis) is not personalized causing interindividual variation in serum drug levels; however, dose optimization is not widely implemented. We hypothesized that some patients are overdosed; thus, drug prescription could be reduced by therapeutic drug monitoring (TDM). METHOD: Independent of disease activity, 239 adults treated for rheumatoid arthritis (n = 99), psoriatic arthritis 15 (n = 48), or spondyloarthritis (n = 92) were recruited for a 48-week prospective, randomized open-label trial. Standard care alone or plus TDM was applied in chronic arthritis patients treated with infliximab (IFX), (n = 81), etanercept (ETN) (n = 79), or adalimumab (ADA) (n = 79). Serum TNFi trough levels assessed at inclusion and every 4 months determined patients within/outside predefined therapeutic intervals, supporting change in prescription or drug switch. The primary endpoint was reduced drug prescription. RESULTS: Compared to standard care, TDM reduced prescribed IFX [-12% (95% confidence interval -20, -3); p = 0.001] and ETN (-15% (-29, 1); p = 0.01], and prolonged the interdosing intervals of ETN [+235% (38, 432); p = 0.02] and ADA [+28% (6, 51); p = 0.04]. Time to drug switch was accelerated (χ2 = 6.03, p = 0.01). No group differences in adverse events, disease activity, or self-reported outcomes were shown, indicating equally sustained remission. CONCLUSIONS: TDM reduced prescription of IFX, ETN, and ADA and identified patients benefiting from accelerated drug switch, thereby minimizing treatment failure, risk of toxicity, and unnecessary adverse events.

Vagal Nerve Stimulation-Modulation of the Anti-Inflammatory Response and Clinical Outcome in Psoriatic Arthritis or Ankylosing Spondylitis.

OBJECTIVES: The vagal nerve exerts an essential pathway in controlling the cholinergic anti-inflammatory reflex. Thus, the study is aimed at investigating the acute effect of a noninvasive transcutaneous vagus nerve stimulation on clinical disease activity and systemic levels of inflammation in patients with psoriatic arthritis or ankylosing spondylitis. METHODS: Twenty patients with psoriatic arthritis (PsA) and 20 patients with ankylosing spondylitis (AS) were included and stimulated bilaterally with a handheld vagal nerve stimulator for 120 seconds 3 times a day for 5 consecutive days. All patients were in remission. Cardiac vagal tone, clinical scores, CRP, and cytokine levels were assessed. RESULTS: In PsA and AS, decreased heart rate was observed, confirming compliance. Furthermore, in PsA, a clear reduction of clinical disease activity associated with a 20% reduction in CRP was shown. In AS, a reduction in interferon-γ, interleukin- (IL-) 8, and 10 was shown. No side effects were described. CONCLUSION: This open-label study provides support for an anti-inflammatory effect of transcutaneous vagus nerve stimulation in patients with psoriatic arthritis and ankylosing spondylitis. The modulated immune response and reduced disease activity and CRP-levels raise the fascinating possibility of using neuromodulation as an add-on to existing pharmacological treatments.

Maternal rheumatoid arthritis during pregnancy and neurodevelopmental disorders in offspring: a systematic review.

Objective: To summarize the available literature on in utero exposure to maternal rheumatoid arthritis (RA) and its influence on the risk of neurodevelopmental disorders (NDDs) in offspring.Method: We conducted a systematic literature review and assessed the internal validity of studies with the Newcastle Ottawa Scale tool.Results: Six studies were included. Three reported on autism spectrum disorders; one cohort study indicated a slightly elevated risk, and two case-control studies reported too few cases for risk assessment. Two large cohort studies reported elevated hazard ratios for epilepsy in offspring, in overlapping populations. One study on attention deficit hyperactivity disorder (ADHD) reported higher odds for maternal RA during pregnancy, among children with ADHD.Conclusion:Few studies were found specifically studying maternal RA during pregnancy and NDDs in offspring. The studies pointed towards a moderately higher risk of these outcomes; however, reporting bias appears to be a problem. Additional studies of appropriate design and power are needed.

Short-term transcutaneous non-invasive vagus nerve stimulation may reduce disease activity and pro-inflammatory cytokines in rheumatoid arthritis: results of a pilot study.

Objective: Rheumatoid arthritis (RA) is a chronic, autoimmune, inflammatory disease. Studies suggest that pro-inflammatory cytokines may be attenuated by the vagus nerve through the cholinergic anti-inflammatory pathway. We aimed to evaluate the anti-inflammatory effects of short-term transcutaneous non-invasive vagus nerve stimulation (n-VNS) applied to the cervical vagus nerve in patients with RA. Method: We conducted a single-centre, open-label, preliminary proof-of-concept study of n-VNS in two cohorts of participants with RA: one with high disease activity (n = 16) and one with low disease activity (n = 20). Disease Activity Score based on 28-joint count-C-reactive protein (DAS28-CRP), cardiac vagal tone, and pro-inflammatory cytokines were measured at baseline and after 1 and 4 days of n-VNS. Results: In the high disease activity group, n-VNS resulted in reductions in DAS28-CRP (4.1 to 3.8, p = 0.02), CRP (8.2 to 6 mg/mL, p = 0.01), and interferon-γ (29.8 to 22.5 pg/mL, p = 0.02). In the low disease activity group, there was no effect on DAS28-CRP, and n-VNS was associated with a decrease in cardiac vagal tone (p = 0.03) and a reduction in interleukin-10 (0.8 to 0.6 pg/mL, p = 0.02). Participants with high disease activity had lower baseline cardiac vagal tone than those with low disease activity (3.6 ± 2 vs 4.9 ± 3 linear vagal scale, p = 0.03). Cardiac vagal tone was negatively associated with DAS28-CRP (r = -0.37, p = 0.03). Overall, n-VNS was well tolerated. Conclusion: This study provides preliminary support for an anti-inflammatory effect of n-VNS in patients with RA. These findings warrant further investigation in larger placebo-controlled trials.

Pamidronate in chronic non-bacterial osteomyelitis: a randomized, double-blinded, placebo-controlled pilot trial.

OBJECTIVE: This is the first randomized double-blinded, placebo-controlled pilot trial to investigate the efficacy of pamidronate in reducing radiological and clinical disease activity in chronic non-bacterial osteomyelitis (CNO). METHOD: Patients received pamidronate or placebo at baseline and weeks 12 and 24. Whole-body magnetic resonance imaging was performed at baseline and weeks 12 and 36, and computed tomography of the anterior chest wall (ACW) at baseline and week 36. Radiological disease activity was systematically scored in the ACW and spine. Patient-reported outcomes [visual analogue scale (VAS) pain, VAS global health, Health Assessment Questionnaire (HAQ), EuroQol-5 Dimensions (EQ-5D), and 36-item Short-Form Health Survey (SF-36)] and biomarkers of bone turnover and inflammation were assessed at baseline and weeks 1, 4, 12, 24, and 36. Data are expressed as median [interquartile range]. RESULTS: Fourteen patients were randomized and 12 were analysed. From baseline to week 36, the radiological disease activity score in the ACW decreased from 5 [4-7] to 2.5 [1-3] in the pamidronate group, but did not change in the placebo group (p = 0.04). From baseline to week 36, VAS pain and VAS global health tended to decrease more in the pamidronate than in the placebo group (p = 0.11, p = 0.08). Physical functioning (HAQ) and health-related quality of life (EQ-5D, SF-36) did not change. Biomarkers of bone turnover decreased only in the pamidronate group (p ≤ 0.02). CONCLUSION: Pamidronate may improve radiological and clinical disease activity in CNO. Methods to score radiological disease activity in adult CNO were suggested. Clinical Trials: NCT02594878.

Vagal influences in rheumatoid arthritis.

Rheumatoid arthritis (RA) is a chronic immune-mediated inflammatory disease with a prevalence of 0.5-1% in Western populations. Conventionally, it is treated with therapeutic interventions that include corticosteroids, disease-modifying anti-rheumatic drugs, and biological agents. RA exerts a significant socio-economic burden and despite the use of existing treatments some patients end up with disabling symptoms. The autonomic nervous system (ANS) is a brain-body interface that serves to regulate homeostasis by integrating the external environment with the internal milieu. The main neural substrate of the parasympathetic branch of the ANS is the vagus nerve (VN). The discovery of the role of the ANS and the VN in mediating and dampening the inflammatory response has led to the proposal that modulation of neural circuits may serve as a valuable therapeutic tool. Recent studies have explored the role of the VN in this inflammatory reflex and have provided evidence that stimulation may represent a novel new therapeutic intervention. Accumulating evidence suggests that modulation of the parasympathetic tone results in a broad physiological multi-level response, including decreased pro-inflammatory cytokine response in terms of tumour necrosis factor-α, interleukin-1 (IL-1), and IL-6, and may result in an enhanced macrophage switch from M1 to M2 cells and potentially an increased level of the anti-inflammatory cytokine IL-10. Therefore, therapeutic electrical modulation of the VN may serve as an alternative, non-pharmacological, neuroimmunomodulatory intervention in RA in the future. This review gives a focused introduction to the mechanistic link between the ANS and the immune system.

Faecal calprotectin detects subclinical bowel inflammation and may predict treatment response in spondyloarthritis.

OBJECTIVE: Intestinal inflammation is frequent in patients with spondyloarthritis (SpA). Here, we test the validity of faecal calprotectin as a marker of intestinal inflammation in SpA patients and evaluate the response of adalimumab in patients with and without intestinal lesions. METHOD: Patients were included on the basis of active SpA with a Bath Ankylosing Spondylitis Disease Activity Index ≥ 4. After a 4 week non-steroidal anti-inflammatory drug washout period, patients were divided into two groups based on faecal calprotectin level (> 100 mg/kg, n = 15, and < 50 mg/kg, n = 15). Adalimumab 40 mg every other week was initiated. Patients with calprotectin >100 mg/kg received an additional 40 mg of adalimumab at baseline. Patients were followed with clinical examination at weeks 12, 20, and 52; magnetic resonance imaging (MRI) at weeks 0, 20, and 52; and endoscopy at weeks 0 and 20. RESULTS: The groups were similar with regard to clinical disease activity measures at baseline. Faecal calprotectin above 100 mg/kg accurately identified patients with intestinal inflammation. Twelve of the 15 patients with elevated calprotectin had bowel lesions, compared to only one patient in the control group. On MRI, the group with elevated calprotectin had more inflammation in the sacroiliac joints. Finally, the group with intestinal inflammation had a better clinical response to adalimumab, as evaluated by the Ankylosing Spondylitis Disease Activity Score. CONCLUSION: Elevated faecal calprotectin accurately identified SpA patients with bowel inflammation and more inflammation on MRI. Elevated faecal calprotectin at baseline may predict a better treatment response.

Hepcidin plasma levels are not associated with changes in haemoglobin in early rheumatoid arthritis patients.

OBJECTIVE: A reduction in haemoglobin level is a frequent complication among rheumatoid arthritis (RA) patients. Hepcidin has been linked to disturbed erythropoiesis. The objective of this study was to investigate the longitudinal changes in hepcidin in patients with early RA. METHOD: Hepcidin plasma concentrations were measured by enzyme-linked immunosorbent assay in patients with early RA (n = 80) and healthy volunteers (HV, n = 40). Haemoglobin and other iron-related proteins were also measured. At baseline, all patients had active disease and were treatment naïve. Patients were treated with disease-modifying anti-rheumatic drugs (DMARDs) and with additional adalimumab (ADA, n = 42) or placebo (PLA, n = 38) during 52 weeks, using a treat-to-target strategy, aiming for a 28-joint Disease Activity Score (DAS28) < 3.2. RESULTS: At baseline, hepcidin levels [median (interquartile range)] were 9.7 ng/mL (5.2-19.4 ng/mL) in DMARD + ADA and 11.3 ng/mL (5.9-19.1 ng/mL) in DMARD + PLA. Both were significantly higher than seen in HV (6.0 ng/mL (3.3-9.3 ng/mL) (p < 0.001). After 12 months, both treatment regimens resulted in normalization of hepcidin. DAS28 correlated with hepcidin at baseline (r = 0.48, p < 0.001). No correlation was observed between levels of haemoglobin and hepcidin at baseline or during the 52 week follow-up. No change in haemoglobin levels was seen as a function of hepcidin changes. In a mixed statistical model, no single factor was connected with the regulation of haemoglobin in early RA. CONCLUSION: The changes in hepcidin were not associated with changes in haemoglobin levels. Thus, hepcidin could not be used as a prognostic marker in patients with early RA.

Increased interleukin (IL)-20 and IL-24 target osteoblasts and synovial monocytes in spondyloarthritis.

The pathogenesis of spondyloarthritis (SpA) involves activation of the innate immune system, inflammation and new bone formation. The two cytokines interleukin (IL)-20 and IL-24 have been shown to link innate immune activation and tissue homeostasis. We hypothesized that these two cytokines are secreted as part of activation of the innate immune system and affect bone homeostasis in SpA. IL-20 and IL-24 were measured in plasma from axial SpA patients (n = 83). Peripheral SpA patients (n = 16) were included for in-vitro cell culture studies. The plasma IL-20 and IL-24 levels were increased in SpA patients compared with healthy controls (HCs) by 57 and 83%, respectively (both P < 0·0001). The Toll-like receptor 4-induced secretion of the two cytokines was greater in SpA peripheral blood mononuclear cells (PBMCs) compared with HC PBMCs. IL-20 and IL-24 increased the production of monocyte chemoattractant protein-1 by activated SpA synovial fluid monocytes, decreased the production of Dickkopf-1 by SpA fibroblast-like synovial cells and induced mineralization in human osteoblasts. Taken together, our findings indicate disease-aggravating functions of IL-20 and IL-24 in SpA.

Collectin liver 1 and collectin kidney 1 and other complement-associated pattern recognition molecules in systemic lupus erythematosus.

The objective of this study was to explore the involvement of collectin liver 1 (CL-L1) and collectin kidney 1 (CL-K1) and other pattern recognition molecules (PRMs) of the lectin pathway of the complement system in a cross-sectional cohort of systemic lupus erythematosus (SLE) patients. Concentrations in plasma of CL-L1, CL-K1, mannan-binding lectin (MBL), M-ficolin, H-ficolin and L-ficolin were determined in 58 patients with SLE and 65 healthy controls using time-resolved immunoflourometric assays. The SLE patients' demographic, diagnostic, clinical and biochemical data and collection of plasma samples were performed prospectively during 4 months. CL-L1, CL-K1 and M-ficolin plasma concentrations were lower in SLE patients than healthy controls (P-values < 0.001, 0.033 and < 0.001, respectively). H-ficolin concentration was higher in SLE patients (P < 0.0001). CL-L1 and CL-K1 plasma concentrations in the individuals correlated in both patients and controls. Patients with low complement component 3 (C3) demonstrated a negative correlation between C3 and CL-L1 and CL-K1 (P = 0.022 and 0.031, respectively). Patients positive for anti-dsDNA antibodies had lower levels of MBL in plasma than patients negative for anti-dsDNA antibodies (P = 0.02). In a cross-sectional cohort of SLE patients, we found differences in the plasma concentrations of CL-L1, CL-K1, M-ficolin and H-ficolin compared to a group of healthy controls. Alterations in plasma concentrations of the PRMs of the lectin pathway in SLE patients and associations to key elements of the disease support the hypothesis that the lectin pathway plays a role in the pathogenesis of SLE.

Interleukin-23 in early disease development in rheumatoid arthritis.

OBJECTIVES: To investigate the levels of interleukin (IL)-23 in patients with early rheumatoid arthritis (eRA) and the effect of anti-tumour necrosis factor (anti-TNF)-α treatment on IL-23 levels. METHOD: Treatment-naïve eRA patients from the OPERA cohort were included (n = 151). Patients were randomized to methotrexate (MTX) plus adalimumab (ADA; n = 75) or MTX plus placebo-ADA (PLA; n = 76). Plasma samples were obtained at baseline and at months 3, 6, and 12 together with values for C-reactive protein (CRP), the 28-joint Disease Activity Score based on CRP (DAS28CRP), scores on the Clinical Disease Activity Index (CDAI) and the Simplified Disease Activity Index (SDAI), visual analogue scale (VAS) for pain/fatigue/physician global and total Sharp/van der Heijde score (TSS). IL-23 was measured at each time point. RESULTS: IL-23 levels decreased significantly in the ADA group from 20.6 pg/mL (IQR 13.1-32.7 pg/mL) at baseline to 18 pg/mL (IQR 7.2-25.0 pg/mL) at 12 months (p < 0.01). No significant decrease in IL-23 level was observed in the PLA group. No associations between baseline IL-23 levels and measures of disease activity (DAS28CRP, CRP, CDAI, or SDAI) at 12 or 24 months were present in the treatment groups. Baseline IL-23 correlated inversely with changes in TSS and symptom duration before diagnosis. CONCLUSIONS: Our data show increased baseline levels and a significant decrease in IL-23 levels in eRA patients treated with anti-TNF-α. The inverse correlation with duration of symptoms before diagnosis supports the importance of IL-23 in the preclinical disease development of RA.

Toll-like receptor 2 and 4 induced interleukin-19 dampens immune reactions and associates inversely with spondyloarthritis disease activity.

Spondyloarthritis (SpA) is a group of immune mediated inflammatory diseases affecting joints, gut, skin and entheses. The inflammatory process involves activation of Toll-like receptor (TLR)-2 and TLR-4 and production of cytokines and chemokines such as monocyte chemoattractant protein 1 (CCL2/MCP-1). This proinflammatory chemokine recruits monocytes to sites of inflammation and is central in the development of several immune-mediated inflammatory diseases. Interleukin (IL)-19 is a member of the IL-10 family of cytokines. IL-19-deficient mice are more susceptible to innate-mediated colitis and develop more severe inflammation in response to injury. In this work, we studied inducers of IL-19 production and effect of IL-19 on the production of CCL2/MCP-1 and proinflammatory cytokines in peripheral blood mononuclear cells (PBMCs) from healthy controls (HCs) and in PBMCs and synovial fluid mononuclear cells (SFMCs) from SpA patients. Further, we measured IL-19 in plasma from HCs and in plasma and synovial fluid from SpA patients. Constitutive IL-19 expression was present in both PBMCs and SFMCs and the secretion of IL-19 was increased by TLR-2 and TLR-4 ligands. Neutralizing IL-19 in HC PBMCs and SpA SFMCs resulted in increased production of CCL-2/MCP-1. IL-19 concentrations were decreased in synovial fluid compared with plasma and associated inversely with disease activity in SpA. SpA SFMCs produced less IL-19 in response to LPS compared with HC PBMCs. These findings indicate that IL-19 production is diminished in SpA. Taken together, impaired IL-19 control of the innate immune system might be involved in the pathogenesis of SpA.

Flow cytometry detection of vitamin D receptor changes during vitamin D treatment in Crohn's disease.

Crohn's disease (CD) is a chronic inflammatory disease associated with a dysregulated T cell response towards intestinal microflora. Vitamin D has immune modulatory effects on T cells through the nuclear vitamin D receptor (VDR) in vitro. It is unclear how oral vitamin D treatment affects VDR expression. The aim of this study was to establish a flow cytometry protocol, including nuclear and cytoplasmic VDR expression, and to investigate the effects of vitamin D treatment on T cell VDR expression in CD patients. The flow cytometry protocol for VDR staining was developed using the human acute monocytic leukaemia cell line (THP-1). The protocol was evaluated in anti-CD3/CD28-stimulated peripheral blood mononuclear cells (PBMCs) from vitamin D3- (n = 9) and placebo-treated (n = 9) CD patients. Anti-VDR-stained PBMCs were examined by flow cytometry, and their cytokine production was determined by cytokine bead array. VDR, CYP27B1 and RXRα mRNA expression levels in CD4(+) T cells were measured by quantitative reverse transcriptase polymerase chain reaction. The flow cytometry protocol enabled detection of cytoplasmic and nuclear VDR expression. The results were confirmed by confocal microscopy and supported by correlation with VDR mRNA expression. VDR expression in CD4(+) T cells increased following stimulation. This VDR up-regulation was inhibited with 30% by vitamin D treatment compared to placebo in CD patients (P = 0027). VDR expression was correlated with in-vitro interferon-γ production in stimulated PBMCs (P = 0.01). Flow cytometry is a useful method with which to measure intracellular VDR expression. Vitamin D treatment in CD patients reduces T cell receptor-mediated VDR up-regulation.

Increased soluble programmed death-1 (sPD-1) is associated with disease activity and radiographic progression in early rheumatoid arthritis.

OBJECTIVES: Programmed death-1 (PD-1) is an immunoregulatory molecule functioning by down-regulating immune responses. PD-1 is present on follicular helper T cells (TFH) and is important in the formation of plasma cells. PD-1 exists in a bioactive soluble form (sPD-1) and is thought to be implicated in disease activity in chronic rheumatoid arthritis (RA). METHOD: We measured sPD-1 at baseline and 9 months after treatment initiation in plasma from early RA patients (n = 34). We tested for correlations with the Disease Activity Score using 28 joint counts (DAS28), the Health Assessment Questionnaire (HAQ) score, immunoglobulin M rheumatoid factor (IgM-RF), anti-cyclic citrullinated peptide (anti-CCP) antibodies, C-reactive protein (CRP), interleukin-21 (IL-21), and total Sharp score (TSS). We also measured sPD-1 in plasma from healthy volunteers (HV) (n = 20) and in plasma and synovial fluid (SF) from patients with chronic RA (> 8 years of disease, n = 30). We further investigated the cellular expression of PD-1 and its ligand PD-L1. RESULTS: sPD-1 concentrations in early [median 0.421 ng/mL, interquartile range (IQR) 0.04-2.560 ng/mL] and chronic (median 0.239 ng/mL, IQR 0.184-0.584 ng/mL) RA were increased compared with HV (median 0.04 ng/mL, IQR 0.04-0.04 ng/mL) (all p < 0.005). In early RA the change in sPD-1 was associated with DAS28 (r = 0.363, p < 0.05) and HAQ score (r = 0.554, p < 0.05) and inversely with TSS at 3-5 years (r = -0.468, p < 0.05). sPD-1 concentration correlated with IgM-RF, anti-CCP antibodies, and IL-21 (all p < 0.05). PD-1 was primarily expressed by synovial memory T cells whereas PD-L1 was mainly expressed by synovial monocytes. CONCLUSIONS: The significantly elevated plasma levels of sPD-1 in early RA, the association with core disease parameters, and the inverse correlation with TSS suggest that sPD-1 is an important mediator in inflammatory and radiographic disease progression.

Levels of lectin pathway proteins in plasma and synovial fluid of rheumatoid arthritis and osteoarthritis.

The innate immune system contributes to the development of rheumatoid arthritis (RA). A potent contributor to such processes is the complement system. The complement system is known to be activated in the inflammatory phases of osteoarthritis (OA). The lectin pathway of the complement system is activated through the recognition of pathogens or altered self-structures by mannan-binding lectin (MBL) or one of the three ficolins in collaboration with MBL-associated serine proteases (MASPs). We assessed the lectin pathway in plasma and synovial fluid (SF) of 27 RA patients and 30 OA patients by measuring MBL, MASP-2, MASP-3, M-ficolin, and H-ficolin. The concentration for all 5 proteins was significantly higher in plasma than in SF (P < 0.001) and the concentration in paired plasma and SF samples correlated in both RA and OA (significance levels between <0.001 and 0.02). The ratio of SF/plasma concentration was for all proteins significantly elevated in RA compared with OA patients (all P < 0.001). The M-ficolin concentration correlated with the neutrophils in both plasma (P = 0.01) and SF (P < 0.001) of RA, and in plasma of 78 controls (P = 0.03). To our knowledge, this is the first report on these proteins in SF, except for MBL where our results are in contrast to the one previous publication. The results support an important physiological role of the neutrophils in determining the M-ficolin levels in both RA and healthy adults. We suggest that quantifications of white blood cells should be included in future clinical investigations of M-ficolin.

Soluble macrophage-derived CD163 is a marker of disease activity and progression in early rheumatoid arthritis.

OBJECTIVES: To investigate the expression of the soluble form of the resident macrophage marker CD163 (sCD163) and its association with core parameters for disease activity, including radiographic progression in early rheumatoid arthritis (RA). METHODS: In a longitudinal sample set from early RA patients (n=34) we measured plasma levels of sCD163 at initiation of treatment and after 9 months of treatment and correlated levels with disease activity in 28 joints (DAS28), C-reactive protein (CRP), erythrocyte sedimentation rate (ESR) and total Sharp score (TSS). We also measured plasma levels of sCD163 in 55 healthy volunteers (HV) and in a transverse sample set of chronic (>8 years of disease) RA patients (n=24) and OA patients (n=24) with paired plasma and joint fluid. RESULTS: Early RA patients had significantly higher plasma levels of sCD163 (1.69mg/l (1.42-2.10)) (median (IQR)) at baseline than after 9 months of treatment (1.28mg/l (0.963-1.66), p=0.001), but not significantly changed compared with HV (1.66mg/l (1.22-2.02)). In early RA patients, baseline levels of sCD163, correlated with DAS28, CRP and ESR. Interestingly, sCD163 at 9 months was associated with radiographic progression (TSS) between year 0 and 5 (r=0.468, p=0.02). Levels of sCD163 were higher in RA patients, than in OA patients and higher in SF than in plasma. CONCLUSIONS: Plasma levels of macrophage derived sCD163 are associated with disease activity and predict radiographic progression in early RA patients, supporting that sCD163 may have a role as a biomarker of disease activity and that resident macrophages are important for joint destruction.