Circulating miRNAs in hand osteoarthritis.

OBJECTIVE: Hand osteoarthritis (OA) is a frequent musculoskeletal disorder with an increasing prevalence during ageing. This study aimed to evaluate circulating microRNAs (miRNAs) in the plasma of patients with hand OA compared with age- and sex-matched healthy control subjects. METHODS: In total, 238 participants (96 with erosive and 73 with non-erosive hand OA patients and 69 healthy control subjects) were included in this study. All patients underwent clinical examinations, including self-reported measures (AUSCAN and Algofunctional index). Radiographs of both hands were scored with the Kallman scale. The profile of miRNAs in plasma was screened using TaqMan™ Low-Density Array, and candidate miRNAs were validated on two quantitative real-time PCR (qRT-PCR) systems (QuantStudio and SmartChip). RESULTS: Of all the 754 miRNAs, 40 miRNAs were different between hand OA patients and healthy control subjects in the screening cohort. Following the two-phase validation process, three miRNAs (miR-23a-3p, miR-146a-5p, and miR-652-3p) were increased in patients with hand OA compared with healthy control subjects and were associated with the AUSCAN sum score and AUSCAN pain. Furthermore, an inverse correlation of miR-222-3p with the Kallman radiographic score was found. The expression of miRNAs did not differ between erosive and non-erosive hand OA. CONCLUSION: The profile of circulating miRNAs could unveil candidate biomarkers associated with hand OA symptoms. Longitudinal studies are required to determine the role of miRNAs in hand OA.

Circulating miR-145 as a marker of therapeutic response to anti-TNF therapy in patients with ankylosing spondylitis.

Circulating miRNAs appear promising therapeutic and prognostic biomarkers. We aimed to investigate the predictive value of circulating miRNAs on the disease outcome following anti-TNF therapy in patients with ankylosing spondylitis (AS). Our study included 19 AS patients assessed at baseline (M0), after three (M3) and twelve months (M12) of therapy. Total RNA was isolated from plasma. A comprehensive analysis of 380 miRNAs using TaqMan Low Density Array (TLDA) was followed by a single assay validation of selected miRNAs. All AS patients had high baseline disease activity and an excellent response to anti-TNF therapy at M3 and M12. TLDA analysis revealed the dysregulation of 17 circulating miRNAs, including miR-145. Single assay validation confirmed that miR-145 is significantly downregulated at M3 compared to baseline. The decrease in the levels of miR-145 from M0 to M3 negatively correlated with the change in BASDAI from M0 to M3; and positively correlated with disease activity improvement from M3 to M12 as per BASDAI and ASDAS. The predictive value of the early change in miR-145 and levels of miR-145 at M3 were further validated by Receiver operating curves analysis. We show thatthe early change in circulating miR-145 may be a predictor for the future outcome ofAS patients treated with TNF inhibitors. Patients with a more significant decrease in miR-145 levels may show further significant improvement of disease activity after 12 months. Monitoring the expression of miR-145 in plasma in AS patients may, therefore, influence our therapeutic decision-making.

Altered dynamics of lipid metabolism in muscle cells from patients with idiopathic inflammatory myopathy is ameliorated by 6 months of training.

KEY POINTS: Regular exercise improves muscle functional capacity and clinical state of patients with idiopathic inflammatory myopathy (IIM). In our study, we used an in vitro model of human primary muscle cell cultures, derived from IIM patients before and after a 6-month intensive supervised training intervention to assess the impact of disease and exercise on lipid metabolism dynamics. We provide evidence that muscle cells from IIM patients display altered dynamics of lipid metabolism and impaired adaptive response to saturated fatty acid load compared to healthy controls. A 6-month intensive supervised exercise training intervention in patients with IIM mitigated disease effects in their cultured muscle cells, improving or normalizing their capacity to handle lipids. These findings highlight the putative role of intrinsic metabolic defects of skeletal muscle in the pathogenesis of IIM and the positive impact of exercise, maintained in vitro by yet unknown epigenetic mechanisms. ABSTRACT: Exercise improves skeletal muscle function, clinical state and quality of life in patients with idiopathic inflammatory myopathy (IIM). Our aim was to identify disease-related metabolic perturbations and the impact of exercise in skeletal muscle cells of IIM patients. Patients underwent a 6-month intensive supervised training intervention. Muscle function, anthropometric and metabolic parameters were examined and muscle cell cultures were established (m. vastus lateralis; Bergström needle biopsy) before and after training from patients and sedentary age/sex/body mass index-matched controls. [14 C]Palmitate was used to determine fat oxidation and lipid synthesis (thin layer chromatography). Cells were exposed to a chronic (3 days) and acute (3 h) metabolic challenge (the saturated fatty acid palmitate, 100 µm). Reduced oxidative (intermediate metabolites, -49%, P = 0.034) and non-oxidative (diglycerides, -38%, P = 0.013) lipid metabolism was identified in palmitate-treated muscle cells from IIM patients compared to controls. Three days of palmitate exposure elicited distinct regulation of oxidative phosphorylation (OxPHOS) complex IV and complex V/ATP synthase (P = 0.012/0.005) and adipose triglyceride lipase in patients compared to controls (P = 0.045) (immunoblotting). Importantly, 6 months of training in IIM patients improved lipid metabolism (CO2 , P = 0.010; intermediate metabolites, P = 0.041) and activation of AMP kinase (P = 0.007), and nearly normalized palmitate-induced changes in OxPHOS proteins in myotubes from IIM patients, in parallel with improvements of patients' clinical state. Myotubes from IIM patients displayed altered dynamics of lipid metabolism and impaired response to metabolic challenge with saturated fatty acid. Our observations suggest that metabolic defects intrinsic to skeletal muscle could represent non-immune pathomechanisms, which can contribute to muscle weakness in IIM. A 6-month training intervention mitigated disease effects in muscle cells in vitro, indicating the existence of epigenetic regulatory mechanisms.

Elevated Tenascin-C Serum Levels in Patients With Axial Spondyloarthritis.

This study aimed to examine serum tenascin C (TNC) in different subsets of axial spondyloarthritis (axSpA) patients. Sixty-one patients fulfilling the Assessment of SpondyloArthritis international Society classification criteria for axSpA and 20 healthy subjects (HS) were included in study. Based on imaging, patients were classified as non-radiographic (n=16) and radiographic (n=45) axSpA. TNC serum levels were determined by ELISA. Disease-related factors including the Bath Ankylosing Spondylitis Disease Activity Index (BASDAI) and C-reactive protein (CRP) levels, were determined. TNC levels were elevated in axSpA patients [535.3 (457.7-677.2) ng/ml] compared to HS [432.1 (329.1-565.9) ng/ml, p=0.007]. Dividing axSpA into radiographic and non-radiographic subsets, the difference in TNC was observed between the radiographic subset and HS [535.3 (434.5-677.2) vs. 432.1 (329.1-565.9) ng/ml, p=0.022]. TNC levels did not correlate with disease activity measures (serum CRP or BASDAI). Nevertheless, the weak correlation of TNC levels with different disease stages (r=0.25, p=0.025) was found, with the highest levels in patients with syndesmophytes. TNC levels are elevated across various subsets of axSpA, and although not related to systemic disease activity, TNC levels might reflect chronic structural spinal changes in axSpA patients. However, its specific role in bone metabolism should be elucidated in further studies.

Impact of immunogenicity on efficacy and tolerability of tumour necrosis factor inhibitors: pooled analysis of biosimilar studies in rheumatoid arthritis.

Objective: SB4, SB2, and SB5 are biosimilars of etanercept (ETN), infliximab (INF), and adalimumab (ADA), respectively. This pooled analysis evaluated the immunogenicity of these treatments across three phase III randomized controlled trials of patients with rheumatoid arthritis (RA). Methods: Patients had to have at least one anti-drug antibody (ADAb) assessment up to the time of the primary endpoint from each study (week 24 in SB4 and SB5 studies; week 30 in SB2 study). The effect of ADAbs on American College of Rheumatology 20% (ACR20) response and the incidences of injection-site reactions (ISRs)/infusion-related reactions (IRRs) were evaluated. Results: The study included 1709 patients. The cumulative incidences of ADAbs were 30.3% in the all-treatments-combined group, 29.1% in the biosimilars combined group, and 31.5% in the reference products combined group. ACR20 response rates were significantly lower in ADAb-positive patients in the all-treatments-combined [odds ratio (95% confidence interval) 1.77 (1.37, 2.27), p < 0.0001], biosimilars combined [2.24 (1.53, 3.30), p < 0.0001], and reference products combined [1.49 (1.06, 2.09), p = 0.0225] groups. ADAb-positive patients also had a higher likelihood of developing ISRs/IRRs in the all-treatments-combined group [0.56 (0.31, 1.01), p = 0.0550], predominantly due to the results observed with SB2 + INF combined rather than with SB4 + ETN or SB5 + ADA combined. Conclusion: In this pooled analysis, ADAbs were associated with reduced efficacy in patients with RA treated with biosimilars (SB4, SB2, and SB5) or their reference products (ETN, INF, and ADA). ADAbs were associated with an increased incidence of ISRs/IRRs in those treated with SB2 + INF. Clinical trial registration numbers: NCT01936181 (SB2 study), NCT01895309 (SB4 study), and NCT02167139 (SB5 study).

Frequency, mutual exclusivity and clinical associations of myositis autoantibodies in a combined European cohort of idiopathic inflammatory myopathy patients.

OBJECTIVES: To determine prevalence and co-existence of myositis specific autoantibodies (MSAs) and myositis associated autoantibodies (MAAs) and associated clinical characteristics in a large cohort of idiopathic inflammatory myopathy (IIM) patients. METHODS: Adult patients with confirmed IIM recruited to the EuroMyositis registry (n = 1637) from four centres were investigated for the presence of MSAs/MAAs by radiolabelled-immunoprecipitation, with confirmation of anti-MDA5 and anti-NXP2 by ELISA. Clinical associations for each autoantibody were calculated for 1483 patients with a single or no known autoantibody by global linear regression modelling. RESULTS: MSAs/MAAs were found in 61.5% of patients, with 84.7% of autoantibody positive patients having a sole specificity, and only three cases (0.2%) having more than one MSA. The most frequently detected autoantibody was anti-Jo-1 (18.7%), with a further 21 specificities each found in 0.2-7.9% of patients. Autoantibodies to Mi-2, SAE, TIF1, NXP2, MDA5, PMScl and the non-Jo-1 tRNA-synthetases were strongly associated (p < 0.001) with cutaneous involvement. Anti-TIF1 and anti-Mi-2 positive patients had an increased risk of malignancy (OR 4.67 and 2.50 respectively), and anti-SRP patients had a greater likelihood of cardiac involvement (OR 4.15). Interstitial lung disease was strongly associated with the anti-tRNA synthetases, anti-MDA5, and anti-U1RNP/Sm. Overlap disease was strongly associated with anti-PMScl, anti-Ku, anti-U1RNP/Sm and anti-Ro60. Absence of MSA/MAA was negatively associated with extra-muscular manifestations. CONCLUSIONS: Myositis autoantibodies are present in the majority of patients with IIM and identify distinct clinical subsets. Furthermore, MSAs are nearly always mutually exclusive endorsing their credentials as valuable disease biomarkers.

Autoantibody Specificities and Type I Interferon Pathway Activation in Idiopathic Inflammatory Myopathies.

Myositis is a heterogeneous group of autoimmune diseases, with different pathogenic mechanisms contributing to the different subsets of disease. The aim of this study was to test whether the autoantibody profile in patients with myositis is associated with a type I interferon (IFN) signature, as in patients with systemic lupus erythematous (SLE). Patients with myositis were prospectively enrolled in the study and compared to healthy controls and to patients with SLE. Autoantibody status was analysed using an immunoassay system and immunoprecipitation. Type I IFN activity in whole blood was determined using direct gene expression analysis. Serum IFN-inducing activity was tested using peripheral blood cells from healthy donors. Blocking experiments were performed by neutralizing anti-IFNAR or anti-IFN-α antibodies. Patients were categorized into IFN high and IFN low based on an IFN score. Patients with autoantibodies against RNA-binding proteins had a higher IFN score compared to patients without these antibodies, and the IFN score was related to autoantibody multispecificity. Patients with dermatomyositis (DM) and inclusion body myositis (IBM) had a higher IFN score compared to the other subgroups. Serum type I IFN bioactivity was blocked by neutralizing anti-IFNAR or anti-IFN-α antibodies. To conclude, a high IFN score was not only associated with DM, as previously reported, and IBM, but also with autoantibody monospecificity against several RNA-binding proteins and with autoantibody multispecificity. These studies identify IFN-α in sera as a trigger for activation of the type I IFN pathway in peripheral blood and support IFN-α as a possible target for therapy in these patients.

The incidence of tuberculosis in patients treated with certolizumab pegol across indications: impact of baseline skin test results, more stringent screening criteria and geographic region.

OBJECTIVES: We report the incidence of tuberculosis (TB) across certolizumab pegol (CZP) clinical trials in rheumatoid arthritis (RA), psoriasis, psoriatic arthritis (PsA) and axial spondyloarthritis (axSpA), before and after the introduction of stricter TB screening. METHODS: TB incidence rates (IRs) were assessed and stratified according to screening guidelines used at the time of CZP trials. Before 2007 (original trials), purified protein derivative (PPD) tuberculin skin test positivity varied according to local standards (induration ≥5 up to ≥20 mm). Since 2007, all CZP trial protocols have been amended, including trials spanning (intermediate) and initiated after 2007 (current), mandating that any patient with PPD≥5 mm receives treatment for latent TB infection (LTBI). All cases of suspected TB or PPD≥5 mm, in pooled data from 5402 CZP patients across all CZP trials up to 2012, underwent blinded central review by independent experts. RESULTS: 44 TB cases were confirmed in pooled CZP RA trials (IR 0.47/100PY, patient-years) with no cases in Japanese RA trials (J-RAPID, HIKARI). Single TB cases were confirmed in psoriasis and axSpA trials (RAPID-axSpA), and no cases in the PsA trial (RAPID-PsA). IR of TB was 0.51/100PY across original or intermediate RA trials and 0.18/100PY in current trials. The majority of TB cases in RA occurred in Eastern (IR 1.02/100PY) and Central Europe (IR 0.58/100PY). Of 242/370 PPD≥5 mm patients who received 9 months isoniazid (INH) treatment for latent TB infection (LTBI), none developed TB, versus 7.8% of 128 untreated PPD≥5 mm patients. CONCLUSIONS: Implementation of more stringent LTBI screening, plus treatment for LTBI, reduced the IR of TB, even when INH was administered after starting CZP therapy.

Genome-wide association study identifies HLA 8.1 ancestral haplotype alleles as major genetic risk factors for myositis phenotypes.

Autoimmune muscle diseases (myositis) comprise a group of complex phenotypes influenced by genetic and environmental factors. To identify genetic risk factors in patients of European ancestry, we conducted a genome-wide association study (GWAS) of the major myositis phenotypes in a total of 1710 cases, which included 705 adult dermatomyositis, 473 juvenile dermatomyositis, 532 polymyositis and 202 adult dermatomyositis, juvenile dermatomyositis or polymyositis patients with anti-histidyl-tRNA synthetase (anti-Jo-1) autoantibodies, and compared them with 4724 controls. Single-nucleotide polymorphisms showing strong associations (P<5×10(-8)) in GWAS were identified in the major histocompatibility complex (MHC) region for all myositis phenotypes together, as well as for the four clinical and autoantibody phenotypes studied separately. Imputation and regression analyses found that alleles comprising the human leukocyte antigen (HLA) 8.1 ancestral haplotype (AH8.1) defined essentially all the genetic risk in the phenotypes studied. Although the HLA DRB1*03:01 allele showed slightly stronger associations with adult and juvenile dermatomyositis, and HLA B*08:01 with polymyositis and anti-Jo-1 autoantibody-positive myositis, multiple alleles of AH8.1 were required for the full risk effects. Our findings establish that alleles of the AH8.1 comprise the primary genetic risk factors associated with the major myositis phenotypes in geographically diverse Caucasian populations.

Decrease in serum interleukin-21 levels is associated with disease activity improvement in patients with recent-onset rheumatoid arthritis.

Interleukin-21 (IL-21) plays an important role in the pathogenesis of rheumatoid arthritis (RA). The aim of our study was to assess serum levels of IL-21 in patients with recent-onset RA in relation to disease activity and response to treatment. We analyzed serum levels of IL-21 in 51 RA patients, both before and 12 weeks after the initiation of treatment and in 36 healthy individuals. Disease activity was assessed at baseline and at weeks 12 and 24 using the Disease Activity Score for 28 joints, serum levels of C-reactive protein, and the total swollen joint count. We found that IL-21 levels were not increased in patients with recent-onset RA compared with healthy controls, but they had significantly decreased from baseline to week 12 during treatment. Baseline levels of IL-21 significantly correlated with measures of disease activity (p<0.02 for all). Although IL-21 levels did not predict achievement of remission, decrease in IL-21 levels correlated with improvement in disease activity after 12 weeks (p<0.02) and also after 24 weeks (p<0.04) of treatment. Our data suggest that circulating IL-21 levels may serve as a biomarker of disease activity and better outcome in early phase of RA.

Validation of RNA extraction procedures focused on micro RNA expression analysis.

The sampling procedure is a crucial step in every kind of experiment. This is also true in gene expression profiling experiments, where high quality and sufficient quantity of extracted RNA plays a significant role in the experimental outcome. We have compared five different RNA extraction protocols from peripheral blood/PBMCs with the aim to define the most suitable method for the miRNA expression profiling experiments. Convincing results in terms of highest quantity and quality were obtained by the TRIzol-chloroform extraction method. The total RNA obtained using this method contained the highest portion of good-quality miRNA molecules, which was also confirmed by gene-specific real-time PCR experiments.

Seroprevalence and specificity of NMO-IgG (anti-aquaporin 4 antibodies) in patients with neuropsychiatric systemic lupus erythematosus.

Neuropsychiatric manifestations are present in 30-40% of patients with systemic lupus erythematosus (SLE). Recently, antibodies to aquaporin-4 (termed AQP4-Ab, or NMO-IgG), a water channel protein, were reported to be present in a subset of patients with SLE and neurological involvement. To evaluate the syndrome specificity and prevalence of serum NMO-IgG/anti-AQP4 antibodies in patients with neuropsychiatric systemic lupus erythematosus (NPSLE). Sera of 76 patients with SLE and neurological symptoms, 50 of whom met the ACR case definitions of NPSLE, were tested for AQP4-Ab in an indirect immunofluorescence assay employing HEK293 cells transfected with recombinant human AQP4. Only one of the examined sera was positive for NMO-IgG/AQP4-Ab. This patient suffered from TM, ranging over two vertebral segments on spinal MRI. None of the 75 NPSLE without TM was found to be seropositive for NMO-IgG/AQP4-Ab. NMO-IgG/AQP4-Ab in NPSLE were present only in a patient with TM and were not detectable in NPSLE patients with other neurological manifestations. Testing for NMO-IgG/AQP4-Ab positivity should be considered in patients presenting with SLE and TM. Non-longitudinally extensive lesions do no not exclude NMO-IgG/AQP4-Ab in patients presenting with SLE and TM.

Novel adipokine fibroblast growth factor 21 is increased in rheumatoid arthritis.

Fibroblast growth factor-21 (FGF-21) has been recently characterized as a new adipokine. The aim of this study was to assess FGF-21 levels in patients with rheumatoid arthritis (RA) and osteoarthritis (OA) and to study the relationship between FGF-21, disease activity and metabolic status. The levels of FGF-21 in serum and synovial fluid samples from 38 patients with RA and 42 control individuals with OA were determined by ELISA. Patients were assessed for disease activity using the disease activity score (DAS28), a serum glucose and lipid profile. Age, sex and BMI-adjusted FGF-21 levels in the serum (p=0.024) and synovial fluid (p=0.010) samples were significantly higher in patients with RA when compared with OA. The levels of FGF-21 in the serum significantly correlated with the levels in the synovial fluid. Serum and synovial fluid FGF-21 levels adjusted for confounders correlated positively with C-reactive protein. The levels of FGF-21 were positively correlated with BMI in patients with RA; however, the levels were not associated with disease activity or lipid profiles. Furthermore, serum FGF-21 levels were significantly higher in seropositive compared with seronegative RA patients. This work shows that patients with seropositive RA have increased levels of FGF-21. The results suggest that FGF-21 is related to BMI but not disease activity or lipid profiles in patients with RA.

Interaction of HLA-DRB1*03 and smoking for the development of anti-Jo-1 antibodies in adult idiopathic inflammatory myopathies: a European-wide case study.

OBJECTIVES: HLA-DRB1*03 is strongly associated with anti-Jo-1-positive idiopathic inflammatory myopathies (IIM) and there is now increasing evidence that Jo-1 antigen is preferentially expressed in lung tissue. This study examined whether smoking was associated with the development of anti-Jo-1 antibodies in HLA-DRB1*03-positive IIM. METHODS: IIM cases were selected with concurrent information regarding HLA-DRB1 status, smoking history and anti-Jo-1 antibody status. DNA was genotyped at DRB1 using a commercial sequence-specific oligonucleotide kit. Anti-Jo-1 antibody status was established using a line blot assay or immunoprecipitation. RESULTS: 557 Caucasian IIM patients were recruited from Hungary (181), UK (99), Sweden (94) and Czech Republic (183). Smoking frequency was increased in anti-Jo-1-positive IIM cases, and reached statistical significance in Hungarian IIM (45% Jo-1-positive vs 17% Jo-1-negative, OR 3.94, 95% CI 1.53 to 9.89, p<0.0001). A strong association between HLA-DRB1*03 and anti-Jo-1 status was observed across all four cohorts (DRB1*03 frequency: 74% Jo-1-positive vs 35% Jo-1-negative, OR 5.55, 95% CI 3.42 to 9.14, p<0.0001). The frequency of HLA-DRB1*03 was increased in smokers. The frequency of anti-Jo-1 was increased in DRB1*03-positive smokers vs DRB1*03-negative non-smokers (42% vs 8%, OR 7.75, 95% CI 4.21 to 14.28, p<0.0001) and DRB1*03-positive non-smokers (42% vs 31%, p=0.08). In DRB1*03-negative patients, anti-Jo-1 status between smokers and non-smokers was not significantly different. No significant interaction was noted between smoking and DRB1*03 status using anti-Jo-1 as the outcome measure. CONCLUSION: Smoking appears to be associated with an increased risk of possession of anti-Jo-1 in HLA-DRB1*03-positive IIM cases. The authors hypothesise that an interaction between HLA-DRB1*03 and smoking may prime the development of anti-Jo-1 antibodies.

Low circulating Dickkopf-1 and its link with severity of spinal involvement in diffuse idiopathic skeletal hyperostosis.

OBJECTIVE: Dickkopf-1 (DKK-1) is an inhibitor of osteoblastogenesis, and its lower levels are linked to new bone formation. The aim of this study was therefore to explore serum levels of DKK-1 and to evaluate DKK-1's association with the severity of spinal involvement in diffuse idiopathic skeletal hyperostosis (DISH). METHODS: Serum levels of total and functional DKK-1 and C-reactive protein (CRP) were measured in 37 patients with DISH and 22 healthy age and sex-matched controls. Plain radiographs of the cervical and thoracic spine were performed, and the diagnosis of DISH was defined using the Resnick criteria. Patients were divided into three groups based on spinal involvement. Bone mineral density (BMD) and bone turnover markers were evaluated in patients with DISH. RESULTS: The levels of total serum DKK-1 were significantly lower in patients with DISH than in healthy controls (p<0.0001). Importantly, low serum levels of DKK-1 were associated with more severe spinal involvement in DISH, independent of age, sex, disease duration, CRP, bone turnover markers or BMD. However, these findings were less significant for functional DKK-1. CONCLUSION: These observations indicate that DKK-1 may play a significant role in bone formation during DISH.

European League Against Rheumatism recommendations for the management of psoriatic arthritis with pharmacological therapies.

BACKGROUND: Psoriatic arthritis (PsA) is a clinically heterogeneous disease. Clear consensual treatment guidance focused on the musculoskeletal manifestations of PsA would be advantageous. The authors present European League Against Rheumatism (EULAR) recommendations for the treatment of PsA with systemic or local (non-topical) symptomatic and disease-modifying antirheumatic drugs (DMARD). METHODS: The recommendations are based on evidence from systematic literature reviews performed for non-steroidal anti-inflammatory drugs (NSAID), glucocorticoids, synthetic DMARD and biological DMARD. This evidence was discussed, summarised and recommendations were formulated by a task force comprising 35 representatives, and providing levels of evidence, strength of recommendations and levels of agreement. RESULTS: Ten recommendations were developed for treatment from NSAID through synthetic DMARD to biological agents, accounting for articular and extra-articular manifestations of PsA. Five overarching principles and a research agenda were defined. CONCLUSION: These recommendations are intended to provide rheumatologists, patients and other stakeholders with a consensus on the pharmacological treatment of PsA and strategies to reach optimal outcomes, based on combining evidence and expert opinion. The research agenda informs directions within EULAR and other communities interested in PsA.

Immunolocalization of protein-bound 3-nitrotyrosine in inflammatory myopathies.

3-nitrotyrosine (3NT) is regarded as a "footprint" of nitric oxide generation. The study aimed at documenting the presence and distribution of 3-nitrotyrosine (3NT) in muscle tissue samples from patients with idiopathic inflammatory myopathies (IIM) as well as from those with non-inflammatory myopathies to consider whether polymyositis (PM) and dermatomyositis (DM) could be distinguished based on 3NT immunohistochemistry in muscle biopsy. Cryosections prepared from muscle biopsies of 54 patients with either IIM, i.e., PM and DM, or various non-inflammatory myopathies were immunostained using monoclonal antibody against 3NT. The 3NT immunostaining was localized to endothelial cells and their close surroundings in muscle biopsies of DM and PM patients but only in those areas of tissue sections where inflammatory cell infiltrates were present. No 3NT positivity was found in tissue sections of IIM patients without inflammatory infiltrates in the studied sample as well as in muscle tissue sections of patients with non-inflammatory myopathies. However, the endothelial cells were also positive in cases of confirmed non-inflammatory myopathies with secondary lymphocytic infiltration (myodystrophies, myasthenia gravis). Despite the pathogenetic significance, the 3NT immunohistochemistry is of low diagnostic value for the differential diagnosis of IIM in muscle biopsy.

Elevated prolactin levels in patients with rheumatoid arthritis: association with disease activity and structural damage.

OBJECTIVES: Prolactin (PRL) is a hormone with cytokine-like activities that has been demonstrated to be involved in immune responses. However, there are inconsistent results related to the role of PRL in rheumatoid arthritis (RA). Therefore, the aim of this study was to evaluate the levels of PRL in serum and synovial fluid in patients with RA and osteoarthritis (OA) and examine whether PRL might be associated with laboratory and clinical disease activity of RA. METHODS: A total of 29 patients with RA and 26 patients with OA were included in the study. The concentration of PRL in the serum and synovial fluid was measured by immunoradiometric assays, and the levels of serum anti-citrullinated protein/peptide autoantibodies (ACPA) and IgM rheumatoid factor (IgM-RF) were analysed by ELISA. Disease activity score (DAS 28) and radiological (Larsen) score were assessed. RESULTS: The levels of PRL in serum (299.55±27.28 vs. 230.59±16.61 mIU/l, p=0.041) as well as in synovial fluid (338.85±33.49 vs. 245.97±21.88 mIU/l, p=0.024) were significantly higher in patients with RA than in patients with OA. A moderate correlation was found between disease activity of RA and levels of PRL in synovial fluid (r=0.485, p=0.010) and the serum PRL levels correlated significantly with the total Larsen score (r=0.484, p=0.014). CONCLUSIONS: The findings of increased prolactin levels in patients with RA lead to the assumption that prolactin may play a role in disease severity and the process of joint damage in RA.

CD161 receptor participates in both impairing NK cell cytotoxicity and the response to glycans and vimentin in patients with rheumatoid arthritis.

We investigated the role of natural killer (NK) cells and CD161, their primary C-type-lectin-like receptor in rheumatoid arthritis (RA). Samples were compared with healthy donors (HD), dermatomyositic (DM), polymyositic (PM), and osteoarthritic (OA) patients. RA, PM, and DM NK cell cytotoxicities significantly decreased relative to the HD and OA NK cells (p<0.0001). These results correlated with an increased expression of NK cell inhibitory receptor CD161, in active disease RA patients. We demonstrated that NK cells are able to respond to mutated citrullinated vimentin (MCV), an RA-specific autoantigen, leading to increases in both PAD4 enzyme and CD161 mRNA expression. MGAT5 glycosidase involvement was detected in GlcNAc metabolism within the synoviocytes of RA patients. Our findings reveal a functional relationship between CD161 expression and NK cell cytotoxicity as well as reactivity to glycans and MCV, thus providing new insight into the pathogenesis of RA and confirming the involvement of surface glycosylation.