Contemporary imaging of rheumatoid arthritis: Clinical role of ultrasound and MRI

Magnetic resonance imaging (MRI) and musculoskeletal ultrasound (MSUS) are sensitive imaging modalities used by clinicians to assist in decision-making in the management of rheumatoid arthritis (RA). This review will examine the utility of MRI and MSUS in diagnosing RA, predicting RA flares, tapering therapy, assessing remission, and examining difficult periarticular features. We will also outline the strengths and weaknesses of utilizing MRI and MSUS as outcome measures in the management of RA.

Changes in clinical disease activity are weakly linked to changes in MRI inflammation on treat-to-target escalation of therapy in rheumatoid arthritis

Background

Rheumatoid arthritis (RA) treat-to-target (T2T) regimens often use the disease activity score (28 joints) incorporating C-reactive protein (DAS28_CRP) as an outcome measure. We compared changes in the DAS28_CRP with changes in magnetic resonance imaging (MRI) inflammation on treatment escalation.

Methods

Eighty seropositive RA patients with active disease were enrolled. Group A (N = 57) escalated to another conventional disease-modifying therapy (cDMARD) combination, and Group B (N = 23) to anti-TNF therapy/cDMARDs. Contrast-enhanced 3T-MRI wrist scans were obtained before and 4 months after regimen change. Scan pairs were scored for inflammation (MRI(i)) and damage. Disease activity was assessed using the DAS28_CRP.

Results

Eighty patients were enrolled and 66 MRI scan pairs were available for analysis. Intra-reader reliability was high: intraclass correlation coefficient (average) 0.89 (0.56–0.97). ΔDAS28_CRP did not differ between groups: Group A, −0.94 (−3.30, 1.61); Group B, −1.53 (−3.59, 0.56) (p = 0.45). ΔMRI(i) also did not differ: Group A, 0 (−25, 10); Group B, −1 (−15, 28) (p = 0.12). Combining groups, ΔMRI(i) correlated weakly with ΔDAS28_CRP (Spearman’s 0.36, p = 0.003). Using multiple linear regression analysis adjusting for confounders, ΔDAS28_CRP was associated with ΔMRI(i) (p = 0.056). Of the individual MRI measures, only Δtenosynovitis correlated with ΔDAS28_CRP (Spearman’s 0.33, p = 0.007). ΔMRI(i) was negatively associated with the MRI erosion score at entry (p = 0.0052).

Conclusions

We report the first study investigating the link between changes in clinical and imaging inflammation in a real-world RA cohort escalating to conventional and biologic DMARDs. The association was significant but relatively weak, suggesting that MRI targets cannot yet be advocated as outcomes for T2T escalation.

Trial registration

ANZCTR 12614000895684. Registered 22 August 2014.

Qualitative study: the experience and impact of living with Behcet's syndrome

AIM

Behcet's syndrome is a rare chronic multisystemic vasculitis of unknown aetiology, is unpredictable and can cause life-threatening complications. This qualitative study aims to explore the experiences of patients living with Behcet's syndrome in New Zealand.

METHODS

Eight English-speaking patients participated in in-depth semi-structured interviews about their experiences of living with Behcet's syndrome. Interviews were recorded and transcribed. Data were analysed using a general inductive thematic approach.

RESULTS

Five themes related to the experience of Behcet's syndrome emerged from the interviews: diagnosis (diagnostic challenge and closure), impact of disease (pain, fatigue, reduced vision, fear and uncertainty), loneliness and isolation (lack of support and information, invisible illness), acquiring resilience (coping, gaining sense of control, support group) and ongoing interactions with health system (specialist care, primary care, need for multidisciplinary care, doctor-patient relationship).

CONCLUSIONS

Behcet's syndrome patients experience difficulties in obtaining a timely and correct diagnosis and contend numerous physical and emotional challenges, often experiencing loneliness and isolation. Establishing trusting doctor-patient relationships, allowing timely access to specialist care and recruiting psychosocial supports will help patients better cope with their illness. Diagnosis and management of Behcet's syndrome requires close collaboration and communication among specialists and general practitioners and improved education on Behcet's syndrome.

Path Analysis Identifies Receptor Activator of Nuclear Factor-κB Ligand, Osteoprotegerin, and Sclerostin as Potential Mediators of the Tophus-bone Erosion Relationship in Gout

OBJECTIVE

To determine the relationship between tophus, erosion and bone remodeling factors in gout.

METHODS

Computed tomography bone erosion and circulating bone factors were measured in adults with tophaceous gout. Multiple regression modeling and path analysis were used to determine predictors of erosion.

RESULTS

Tophus number, Māori or Pacific ethnicity, creatinine, receptor activator of nuclear factor-κB ligand (RANKL), osteoprotegerin (OPG), and sclerostin were independently associated with erosion. Path analysis showed a direct effect of tophus number on erosion, partially mediated through OPG, RANKL, and sclerostin.

CONCLUSION

Tophus number is strongly associated with bone erosion in gout. Circulating RANKL, OPG, and sclerostin are potential mediators of tophus-related erosion.

A comparative MRI study of cartilage damage in gout versus rheumatoid arthritis

INTRODUCTION

Magnetic resonance imaging (MRI) is useful for detecting joint inflammation and damage in the inflammatory arthropathies. This study aimed to investigate MRI cartilage damage and its associations with joint inflammation in patients with gout compared with a group with rheumatoid arthritis (RA).

METHODS

Forty patients with gout and 38 with seropositive RA underwent 3T-MRI of the wrist with assessment of cartilage damage at six carpal sites, using established scoring systems. Synovitis and bone oedema (BME) were graded according to Rheumatoid Arthritis MRI Scoring System criteria. Cartilage damage was compared between the groups adjusting for synovitis and disease duration using logistic regression analysis.

RESULTS

Compared with RA, there were fewer sites of cartilage damage and lower total damage scores in the gout group (P = 0.02 and 0.003), adjusting for their longer disease duration and lesser degree of synovitis. Cartilage damage was strongly associated with synovitis in both conditions (R = 0.59, P < 0.0001 and R = 0.52, P = 0.0045 respectively) and highly correlated with BME in RA (R = 0.69, P < 0.0001) but not in gout (R = 0.095, P = 0.56).

CONCLUSIONS

Cartilage damage is less severe in gout than in RA, with fewer sites affected and lower overall scores. It is associated with synovitis in both diseases, likely indicating an effect of pro-inflammatory cytokine production on cartilage integrity. However, the strong association between cartilage damage and BME observed in RA was not identified in gout. This emphasizes differences in the underlying pathophysiology of joint damage in these two conditions.

Urate crystal deposition in asymptomatic hyperuricaemia and symptomatic gout: a dual energy CT study

BACKGROUND

The aim of this study was to compare the frequency and volume of dual energy CT (DECT) urate deposits in people with asymptomatic hyperuricaemia and symptomatic gout.

METHODS

We analysed DECT scans of the feet from asymptomatic individuals with serum urate ≥540 µmol/L (n=25) and those with crystal proven gout without clinically apparent tophi (n=33).

RESULTS

DECT urate deposits were observed in 6/25 (24%) participants with asymptomatic hyperuricaemia, 11/14 (79%) with early gout (predefined as disease duration ≤3 years) and 16/19 (84%) with late gout (p<0.001). DECT urate deposition was observed in both joints and tendons in the asymptomatic hyperuricaemia group, but significantly less frequently than in those with gout (p≤0.001 for both joint and tendon sites). The volume of urate deposition was also significantly lower in those with asymptomatic hyperuricaemia, compared with the early and the late gout groups (p<0.01 for both comparisons). Similar urate volumes were observed in the early and late gout groups.

CONCLUSIONS

Although subclinical urate deposition can occur in people with asymptomatic hyperuricaemia, these deposits occur more frequently and at higher volumes in those with symptomatic gout. These data suggest that a threshold of urate crystal volume may be required before symptomatic disease occurs.

Insights into rheumatoid arthritis from use of MRI

Magnetic resonance imaging (MRI) is ideal for imaging the joints of rheumatoid arthritis (RA) patients. It produces anatomically detailed images of bone, cartilage, tendons and synovial membrane. It can reveal structural damage, in the form of bone erosion, cartilage thinning and/or tendon rupture, and regions of inflammation, using sequences that reveal water content and vascularity. MRI synovitis, tenosynovitis and bone oedema/osteitis all have prognostic significance, and MRI studies of RA have helped elucidate the mechanisms whereby bone and synovial inflammation lead to joint damage. Bone oedema/osteitis has become an important imaging biomarker, and can be used to help predict progression from undifferentiated arthritis to definite RA. Recent MRI studies have confirmed that subclinical inflammation is often present in patients in clinical remission, and these data may affect disease management. Finally, recent clinical trials are reviewed, in which MRI outcome measures are being established as sensitive response markers.

Interactions between tenocytes and monosodium urate monohydrate crystals: implications for tendon involvement in gout

OBJECTIVES

Advanced imaging studies have demonstrated that urate deposition in periarticular structures, such as tendons, is common in gout. The aim of this study was to investigate the effects of monosodium urate monohydrate (MSU) crystals on tenocyte viability and function.

METHODS

The histological appearance of tendons in joints affected by advanced gout was examined using light microscopy. In vitro, colorimetric assays and flow cytometry were used to assess cell viability in primary rat and primary human tenocytes cultured with MSU crystals. Real-time PCR was used to determine changes in the relative mRNA expression levels of tendon-related genes, and Sirius red staining was used to measure changes in collagen deposition in primary rat tenocytes.

RESULTS

In joint samples from patients with gout, MSU crystals were identified within the tendon, adjacent to and invading into tendon, and at the enthesis. MSU crystals reduced tenocyte viability in a dose-dependent manner. MSU crystals decreased the mRNA expression of tendon collagens, matrix proteins and degradative enzymes and reduced collagen protein deposition by tenocytes.

CONCLUSIONS

These data indicate that MSU crystals directly interact with tenocytes to reduce cell viability and function. These interactions may contribute to tendon damage in people with advanced gout.

MRI in rheumatoid arthritis: a useful tool for the clinician?

Over the last two decades, MRI has emerged as an important clinical tool to assist in the diagnosis and management of rheumatic disease. In rheumatoid arthritis (RA), MRI has improved our understanding of the pathological basis of disease and has provided new information about imaging features that reflect joint inflammation and damage. Using MRI, we can now directly observe inflammation involving the synovial membrane and tenosynovium, plus joint damage including bone erosion and cartilage thinning. Inflammation of bone beneath the joint (osteitis) appears as bone oedema which is a feature unique to MRI and yields important diagnostic and prognostic information in patients with inflammatory arthritis. With the introduction of biologics to rheumatology clinical practice, sensitive tools are required to monitor disease activity and progression, so that the disease suppressing effect of these new agents can be measured. MRI fits the bill for this role as it can inform the clinician about the development of bone erosions well before plain radiography, and its ability to reveal cartilage damage is emerging. The use of MRI as a marker of outcome in clinical trials is being paralleled by its increasing role in the clinic. Both extremity and high field MRI have clinical applications in RA and need to be considered along with other advanced imaging techniques as useful tools to add to the clinician's armamentarium. This review will summarise recent advances in this field and will apply current knowledge to specific clinical scenarios relevant to modern rheumatology practice.

Exploratory study of radiographic change in patients with tophaceous gout treated with intensive urate-lowering therapy

OBJECTIVE

Tophi are strongly associated with structural damage in gout, and urate-lowering therapy reduces tophus size. Pegloticase leads to dramatic reductions in serum urate and subcutaneous tophi in treatment responders. The aim of this analysis was to examine whether profound urate lowering can alter radiographic findings in gout.

METHODS

Serial plain radiographs of the hands and feet were obtained from 8 patients with tophaceous gout treated with pegloticase. Radiographs were scored for erosion and joint space narrowing (JSN) according to the gout-modified Sharp/van der Heijde method. Scorers were blinded to each other's scores and to the clinical characteristics of the patients (including the clinical response to pegloticase). A detailed qualitative site-by-site analysis was undertaken to define additional changes observed from baseline.

RESULTS

All patients experienced a profound urate-lowering response (serum urate level <1 mg/dl) during pegloticase treatment. For the entire group, the median total radiographic scores reduced from 69.25 (range 1.5-138) at baseline to 57.25 (range 1.5-110) at 12 months (P = 0.02). Median erosion scores reduced over 1 year (P = 0.008), but JSN scores did not change (P = 0.50). Further reductions were observed in total scores and erosion scores in 5 patients with 24-month followup films (one-way analysis of variance P = 0.009 for total score, 0.02 for erosion, and 0.95 for JSN). Qualitative site-by-site analysis identified regression of soft tissue masses, increased sclerosis, and filling in of erosions in the followup films.

CONCLUSION

This exploratory study suggests that profound urate lowering can lead to improvement in structural damage, particularly bone erosion, in patients with tophaceous gout.

Outcome measures in acute gout: a systematic literature review

OBJECTIVE

Five core domains have been endorsed by Outcome Measures in Rheumatology (OMERACT) for acute gout: pain, joint swelling, joint tenderness, patient global assessment, and activity limitation. We evaluated instruments for these domains according to the OMERACT filter: truth, feasibility, and discrimination.

METHODS

A systematic search strategy for instruments used to measure the acute gout core domains was formulated. For each method, articles were assessed by 2 reviewers to summarize information according to the specific components of the OMERACT filter.

RESULTS

Seventy-seven articles and abstracts met the inclusion criteria. Pain was most frequently reported (76 studies, 20 instruments). The pain instruments used most often were 100 mm visual analog scale (VAS) and 5-point Likert scale. Both methods have high feasibility, face and content validity, and within- and between-group discrimination. Four-point Likert scales assessing index joint swelling and tenderness have been used in numerous acute gout studies; these instruments are feasible, with high face and content validity, and show within- and between-group discrimination. Five-point Patient Global Assessment of Response to Treatment (PGART) scales are feasible and valid, and show within- and between-group discrimination. Measures of activity limitations were infrequently reported, and insufficient data were available to make definite assessments of the instruments for this domain.

CONCLUSION

Many different instruments have been used to assess the acute gout core domains. Pain VAS and 5-point Likert scales, 4-point Likert scales of index joint swelling and tenderness and 5-point PGART instruments meet the criteria for the OMERACT filter.

Relationship between structural joint damage and urate deposition in gout: a plain radiography and dual-energy CT study

Objectives

The aim of this work was to examine the relationship between joint damage and monosodium urate (MSU) crystal deposition in gout.

Methods

Plain radiographs and dual-energy CT (DECT) scans of the feet were prospectively obtained from 92 people with tophaceous gout. Subcutaneous tophus count was recorded. The ten metatarsophalangeal joints were scored on plain radiography for Sharp–van der Heijde erosion and joint space narrowing (JSN) scores, and presence of spur, osteophyte, periosteal new bone and sclerosis (920 total joints). DECT scans were analysed for the presence of MSU crystal deposition at the same joints.

Results

DECT MSU crystal deposition was more frequently observed in joints with erosion (OR (95% CI) 8.5 (5.5 to 13.1)), JSN (4.2 (2.7 to 6.7%)), spur (7.9 (4.9 to 12.8)), osteophyte (3.9 (2.5 to 6.0)), periosteal new bone (7.0 (4.0 to 12.2)) and sclerosis (6.9 (4.6 to 10.2)), p<0.0001 for all. A strong linear relationship was observed in the frequency of joints affected by MSU crystals with radiographic erosion score (p<0.0001). The number of joints at each site with MSU crystal deposition correlated with all features of radiographic joint damage (r>0.88, p<0.05 for all). In linear regression models, the relationship between MSU crystal deposition and all radiographic changes except JSN and osteophytes persisted after adjusting for subcutaneous tophus count, serum urate concentration and disease duration.

Conclusions

MSU crystals are frequently present in joints affected by radiographic damage in gout. These findings support the concept that MSU crystals interact with articular tissues to influence the development of structural joint damage in this disease.

MRI osteitis predicts cartilage damage at the wrist in RA: a three-year prospective 3T MRI study examining cartilage damage

Introduction

Cartilage damage impacts on patient disability in rheumatoid arthritis (RA). The aims of this magnetic resonance imaging (MRI) study were to investigate cartilage damage over three years and determine predictive factors.

Methods

A total of 38 RA patients and 22 controls were enrolled at t = 0 (2009). After 3 years, clinical and MRI data were available in 28 patients and 15 controls. 3T MRI scans were scored for cartilage damage, bone erosion, synovitis and osteitis. A model was developed to predict cartilage damage from baseline parameters.

Results

Inter-reader reliability for the Auckland MRI cartilage score (AMRICS) was high for status scores; intraclass correlation coefficient (ICC), 0.90 (0.81 to 0.95) and moderate for change scores (ICC 0.58 (0.24 to 0.77)). AMRICS scores correlated with the Outcome MEasures in Rheumatoid Arthritis Clinical Trials (OMERACT) MRI joint space narrowing (jsn) and X-Ray (XR) jsn scores (r =0.96, P < 0.0001 and 0.80, P < 0.0001, respectively). AMRICS change scores were greater for RA patients than controls (P = 0.06 and P = 0.04 for the two readers). Using linear regression, baseline MRI cartilage, synovitis and osteitis scores predicted the three-year AMRICS (R² = 0.67, 0.37 and 0.39, respectively). A multiple linear regression model predicted the three-year AMRICS (R² = 0.78). Baseline radial osteitis predicted increased cartilage scores at the radiolunate and radioscaphoid joints, P = 0.0001 and 0.0012, respectively and synovitis at radioulnar, radiocarpal and intercarpal-carpometacarpal joints also influenced three-year cartilage scores (P-values of 0.001, 0.04 and 0.01, respectively).

Conclusions

MRI cartilage damage progression is preceded by osteitis and synovitis but is most influenced by pre-existing cartilage damage suggesting primacy of the cartilage damage pathway in certain patients.

Is rheumatoid arthritis a B-cell haematological disease with a predilection for the joints? Following the B cell thread to its logical conclusion

B-cell depleting therapy (BCDT) is effective in suppressing synovitis and erosions in rheumatoid arthritis suggesting that a cell of the B-lymphocyte lineage is critical in the pathogenesis of this disease. Non-Hodgkins lymphoma (NHL) also responds to BCDT but multiple myeloma (MM), does not as cells have differentiated beyond the CD20-bearing stage. However, there are similarities between B-NHL, MM and RA that suggest all 3 conditions could be initiated and perpetuated by the same cellular players. Numerous plasma cells and B cells are present within rheumatoid synovial membrane, and subarticular bone where they contribute to osteitis. On MRI scans this appears as bone oedema, which has been demonstrated to precede the development of bone erosions. Plasma cell clonality has been detected within RA synovial membrane and bone marrow. It is proposed that RA could represent a "forme fruste" of a B cell neoplastic condition, with production of autoantibodies that target a self-antigen within the joint. The activation of rheumatoid bone osteoclasts by anticitrullinated protein antibodies supports this theory. The erosions of RA would have parallels with the lytic lesions of MM but autoantigen targeting dictates that erosions occur at joint margins. This theory is discussed from rheumatologic and haematologic perspectives.

Determining a Magnetic Resonance Imaging Inflammatory Activity Acceptable State Without Subsequent Radiographic Progression in Rheumatoid Arthritis: Results from a Followup MRI Study of 254 Patients in Clinical Remission or Low Disease Activity

Objective.

To assess the predictive value of magnetic resonance imaging (MRI)-detected subclinical inflammation for subsequent radiographic progression in a longitudinal study of patients with rheumatoid arthritis (RA) in clinical remission or low disease activity (LDA), and to determine cutoffs for an MRI inflammatory activity acceptable state in RA in which radiographic progression rarely occurs.

Methods.

Patients with RA in clinical remission [28-joint Disease Activity Score-C-reactive protein (DAS28-CRP) < 2.6, n = 185] or LDA state (2.6 ≤ DAS28-CRP < 3.2, n = 69) with longitudinal MRI and radiographic data were included from 5 cohorts (4 international centers). MRI were assessed according to the Outcome Measures in Rheumatology (OMERACT) RA MRI scoring system (RAMRIS). Statistical analyses included an underlying conditional logistic regression model stratified per cohort, with radiographic progression as dependent variable.

Results.

A total of 254 patients were included in the multivariate analyses. At baseline, synovitis was observed in 95% and osteitis in 49% of patients. Radiographic progression was observed in 60 patients (24%). RAMRIS synovitis was the only independent predictive factor in multivariate analysis. ROC analysis identified a cutoff value for baseline RAMRIS synovitis score of 5 (maximum possible score 21). Rheumatoid factor (RF) status yielded a significant interaction with synovitis (p value = 0.044). RF-positive patients with a RAMRIS synovitis score of > 5 vs ≤ 5, had an OR of 4.4 (95% CI 1.72–11.4) for radiographic progression.

Conclusion.

High MRI synovitis score predicts radiographic progression in patients in clinical remission/LDA. A cutoff point for determining an MRI inflammatory activity acceptable state based on the RAMRIS synovitis score was established. Incorporating MRI in future remission criteria should be considered.

Update on the OMERACT Magnetic Resonance Imaging Task Force: Research and Future Directions

Magnetic resonance imaging (MRI) provides an important biomarker across a range of rheumatological diseases. At the Outcome Measures in Rheumatology (OMERACT) 11 meeting, the MRI task force continued its work of developing and improving the use of MRI outcomes for use in clinical trials. The breadth of pathology in the Rheumatoid Arthritis MRI Score has been strengthened with further work on the development of a joint space narrowing score, and a series of exercises presented at OMERACT 11 demonstrated good reliability and construct validity for this assessment. Understanding the importance of residual inflammation after RA treatment remains a major focus of the group’s work. Analyses were presented on defining the level of synovitis (using MRI scores of a single hand) that would predict absence of erosion progression. The development of the OMERACT Hand Osteoarthritis MRI score has continued with substantial work presented on its iterative development, including pathology definition, scaling, and subsequent reliability of the score. Optimizing the role of MRI as a robust biomarker and surrogate outcome remains a priority for this group.

Iterative Development and Reliability of the OMERACT Hand Osteoarthritis MRI Scoring System

Objective.

To develop and test the interreader reliability of the OMERACT Hand Osteoarthritis Magnetic Resonance Scoring System (HOAMRIS) for assessment of structural and inflammatory hand OA features in the interphalangeal joints.

Methods.

The HOAMRIS was developed through an iterative process. Selection of features and their scaling was agreed upon through consensus by members of the OMERACT Magnetic Resonance Imaging (MRI) Task Force, using the Oslo Hand Osteoarthritis (OA) MRI Score system as a template. Two reliability exercises were performed, in which 6 and 4 readers participated, respectively. After the first exercise, an atlas was developed and used in the second exercise to facilitate reading. In each exercise, readers independently scored 8 MRI scans from the Oslo Hand OA cohort (coronal/axial short-tau inversion recovery and coronal/axial/sagittal T1-weighted fat-suppressed pre-/post-Gadolinium images). Interreader reliability was assessed by intraclass correlation coefficients (ICC), percentage exact and close agreement (PEA/PCA).

Results.

The preliminary OMERACT HOAMRIS included assessment of synovitis, erosive damage, cysts, osteophytes, cartilage space loss, malalignment, and bone marrow lesions (BML), of which all were scored on a 0–3 scale for normal, mild, moderate, and severe (increments of 0.5 for synovitis, erosive damage, and BML). In the first exercise, most features showed good to very good ICC values (0.64–0.94), except synovitis (0.34). In the second exercise using the atlas, the ICC values were > 0.74 for all MRI features, and the PEA/PCA values were higher than in the first exercise.

Conclusion.

A preliminary HOAMRIS with good to very good interreader reliability was developed. Longitudinal studies are needed to assess its sensitivity to change.

The OMERACT-RAMRIS Rheumatoid Arthritis Magnetic Resonance Imaging Joint Space Narrowing Score: Intrareader and Interreader Reliability and Agreement with Computed Tomography and Conventional Radiography

Objective.

To test the intrareader and interreader reliability of assessment of joint space narrowing (JSN) in rheumatoid arthritis (RA) wrist and metacarpophalangeal (MCP) joints on magnetic resonance imaging (MRI) and computed tomography (CT) using the newly proposed OMERACT-RAMRIS JSN scoring method, and to compare JSN assessment on MRI, CT, and radiography.

Methods.

After calibration of readers, MRI and CT images of the wrist and second to fifth MCP joints from 14 patients with RA and 1 healthy control were assessed twice for JSN by 3 readers, blinded to clinical and imaging data. Radiographs were scored by the Sharp/van der Heijde method. Intraclass correlation coefficients (ICC) and smallest detectable differences (SDD) were calculated, and the performance of various simplified scores was investigated.

Results.

Both MRI and CT showed high intrareader (ICC ≥ 0.95) and interreader (ICC ≥ 0.94) reliability for total (wrist + MCP) assessment of JSN. Agreement was generally lower for MCP joints than for wrist joints, particularly for CT. Intrareader SDD for MCP/wrist/MCP + wrist were 1.2/6.1/6.4 JSN units for MRI, while 2.7/8.3/9.9 JSN units for CT. JSN on MRI and CT correlated moderately well with corresponding radiographic JSN scores (MCP 2–5: 0.49 and 0.56; wrist areas assessed by Sharp/van der Heijde: 0.80 and 0.95), and high ICC between scores on MRI and CT were demonstrated (MCP: 0.94; wrist: 0.92; MCP + wrist: 0.92).

Conclusion.

The OMERACT-RAMRIS MRI JSN scoring system showed high intrareader and interreader reliability, and high correlation with CT scores of JSN. The suggested JSN score may, after further validation in longitudinal studies, become a useful tool in RA clinical trials.

Gout in 2013. Imaging, genetics and therapy: gout research continues apace

In 2013, much progress has occurred in gout research. Imaging continues to help elucidate aspects of pathophysiology and now suggests that healing of erosions could occur when urate levels are reduced dramatically. New genetic loci associated with hyperuricaemia have been identified and management strategies for prophylaxis of gout flares continue to evolve.

The Effects of Monosodium Urate Monohydrate Crystals on Chondrocyte Viability and Function: Implications for Development of Cartilage Damage in Gout

Objective.

Cartilage damage is frequently observed in advanced destructive gout. The aim of our study was to investigate the effects of monosodium urate monohydrate (MSU) crystals on chondrocyte viability and function.

Methods.

The alamarBlue assay and flow cytometry were used to assess the viability of primary human chondrocytes and cartilage explants following culture with MSU crystals. The number of dead chondrocytes in cartilage explants cultured with MSU crystals was quantified. Real-time PCR was used to determine changes in the relative mRNA expression levels of chondrocytic genes. The histological appearance of cartilage in joints affected by gout was also examined.

Results.

MSU crystals rapidly reduced primary human chondrocyte and cartilage explant viability in a dose-dependent manner (p < 0.01 for both). Cartilage explants cultured with MSU crystals had a greater percentage of dead chondrocytes at the articular surface compared to untreated cartilage (p = 0.004). Relative mRNA expression of type II collagen and the cartilage matrix proteins aggrecan and versican was decreased in chondrocytes following culture with MSU crystals (p < 0.05 for all). However, expression of the degradative enzymes ADAMTS4 and ADAMTS5 was increased (p < 0.05 for both). In joints affected by gout, normal cartilage architecture was lost, with empty chondrocyte lacunae observed.

Conclusion.

MSU crystals have profound inhibitory effects on chondrocyte viability and function. Interactions between MSU crystals and chondrocytes may contribute to cartilage damage in gout through reduction of chondrocyte viability and promotion of a catabolic state.

Lack of change in urate deposition by dual-energy computed tomography among clinically stable patients with long-standing tophaceous gout: a prospective longitudinal study

Introduction

Dual-energy computed tomography (DECT) has potential for monitoring urate deposition in patients with gout. The aim of this prospective longitudinal study was to analyse measurement error of DECT urate volume measurement in clinically stable patients with tophaceous gout.

Methods

Seventy-three patients with tophaceous gout on stable therapy attended study visits at baseline and twelve months. All patients had a comprehensive clinical assessment including serum urate testing and DECT scanning of both feet. Two readers analysed the DECT scans for the total urate volume in both feet. Analysis included inter-reader intraclass correlation coefficients (ICCs) and limits of agreement, and calculation of the smallest detectable change.

Results

Mean (standard deviation) serum urate concentration over the study period was 0.38 (0.09) mmol/L. Urate-lowering therapy was prescribed in 70 (96%) patients. The median (interquartile range) baseline DECT urate volume was 0.49 (0.16, 2.18) cm³, and change in DECT urate volume was -0.01 (-0.40, 0.28) cm³. Inter-reader ICCs were 1.00 for baseline DECT volumes and 0.93 for change values. Inter-reader bias (standard deviation) for baseline volumes was -0.18 (0.63) cm³ and for change was -0.10 (0.93) cm³. The smallest detectable change was 0.91 cm³. There were 47 (64%) patients with baseline DECT urate volumes <0.91 cm³. Higher serum urate concentrations were observed in patients with increased DECT urate volumes above the smallest detectable change (P = 0.006). However, a relationship between changes in DECT urate volumes and serum urate concentrations was not observed in the entire group.

Conclusions

In patients with tophaceous gout on stable conventional urate-lowering therapy the measurement error for DECT urate volume assessment is substantially greater than the median baseline DECT volume. Analysis of patients commencing or intensifying urate-lowering therapy should clarify the optimal use of DECT as a potential outcome measure in studies of chronic gout.

Tendon involvement in the feet of patients with gout: a dual-energy CT study

OBJECTIVES

To examine the frequency and patterns of monosodium urate (MSU) crystal deposition in tendons and ligaments in patients with gout using dual-energy CT (DECT).

METHODS

Ninety-two patients with tophaceous gout had DECT scanning of both feet. Two readers scored the DECT scans for MSU crystal deposition at 20 tendon/ligament sites and 42 bone sites (total 1840 tendon/ligament sites and 3864 bone sites).

RESULTS

MSU crystal deposition was observed by both readers in 199/1840 (10.8%) tendon/ligament sites and in 399/3864 (10.3%) bone sites (p=0.60). The Achilles tendon was the most commonly involved tendon/ligament site (39.1% of all Achilles tendons), followed by the peroneal tendons (18.1%). Tibialis anterior and the extensor tendons were involved less commonly (7.6-10.3%), and the other flexor tendons, plantar fascia and deltoid ligaments were rarely involved (<5%) (p<0.0001 between sites). Involvement of the enthesis alone was more common in the Achilles tendon (OR (95% CI) 74.5 (4.4 to 1264), p<0.0001), as was any involvement of the enthesis (OR (95% CI) 6.8 (3.6 to 13.0), p<0.0001).

CONCLUSIONS

Tendons are commonly affected by MSU crystal deposition in patients with tophaceous gout. The patterns of MSU crystal deposition suggest that biomechanical strain or other local factors may contribute to deposition of MSU crystals.

Bone marrow edema and osteitis in rheumatoid arthritis: the imaging perspective

Magnetic resonance imaging bone marrow edema is an imaging feature that has been described in many conditions, including osteomyelitis, overuse syndromes, avascular necrosis, trauma, and inflammatory arthritides. In rheumatoid arthritis (RA), bone edema has special significance as it has been shown to be a common and widespread lesion that is often apparent at the hands and wrists but has also been described elsewhere, including the feet. It may occur in early or late disease and has been shown in several large cohort studies to have major negative implications for prognosis. It is the strongest predictor of erosive progression yet to be identified and characteristically occurs in those patients with the most aggressive and potentially disabling disease. In patients with undifferentiated arthritis, bone edema also predicts progression to criteria-positive RA, both independently and to a greater extent when combined with anti-cyclic citrullinated peptide status or rheumatoid factor positivity. Its histological correlate in the late stages of RA has been shown to be osteitis, in which the bone marrow beneath the joint is invaded by an inflammatory and vascular lymphoplasmacytic infiltrate. This lies adjacent to trabecular bone, where increased numbers of osteoclasts have been observed within resorption lacunae, suggesting a mechanistic link between inflammation and erosive bone damage. This could lead to erosion both of the overlying cortex, leading to classic radiographic rheumatoid erosions, and of local trabecular bone, possibly contributing to periarticular osteopenia and cyst formation. In addition to synovitis, osteitis is now regarded as a major rheumatoid lesion that is responsive to therapeutic intervention.

Prescription and dosing of urate-lowering therapy, rather than patient behaviours, are the key modifiable factors associated with targeting serum urate in gout

Background

Long term serum urate (SU) lowering to a target of <0.36 mmol/l (6 mg/dl) is recommended for effective gout management. However, many studies have reported low achievement of SU targets. The aim of this cross-sectional study was to examine the clinical and psychological factors associated with SU targets in patients with gout.

Methods

Patients with gout for <10 years were recruited from primary and secondary care settings. SU target was defined as SU concentration <0.36 mmol/L at the time of the study visit. Both clinical and psychological factors associated with SU target were analysed. The relationship between SU target and measures of gout activity such as flare frequency, tophi, work absences, and Health Assessment Questionnaire-II was also analysed.

Results

Of the 273 patients enrolled into the study, 89 (32.6%) had SU concentration <0.36 mmol/L. Urate-lowering therapy (ULT) use was strongly associated with SU target (p < 0.001). In those patients prescribed ULT (n = 181), allopurinol dose, patient confidence to keep SU under control, female sex, and ethnicity were independently associated with SU target. Other patient psychological measures and health-related behaviours, including adherence scores, were not independently associated with SU target in those taking ULT. Creatinine clearance, diuretic use, age, and body mass index were not associated with SU target. Patients at SU target reported lower gout flare frequency, compared with those not at target (p = 0.03).

Conclusions

ULT prescription and dosing are key modifiable factors associated with achieving SU target. These data support interventions focusing on improved use of ULT to optimise outcomes in patients with gout.

Characterization of new bone formation in gout: a quantitative site-by-site analysis using plain radiography and computed tomography

INTRODUCTION

Radiographic descriptions of gout have noted the tendency to hypertrophic bone changes. The aim of this study was to characterize the features of new bone formation (NBF) in gout, and to determine the relationship between NBF and other radiographic features of disease, particularly erosion and tophus.

METHODS

Paired plain radiographs (XR) and computed tomography (CT) scans of 798 individual hand and wrist joints from 20 patients with gout were analyzed. Following a structured review of a separate set of images, films were scored for the presence of the following features of NBF: spur, osteophyte, periosteal NBF, ankylosis and sclerosis. The relationship between NBF and other radiographic features was analyzed.

RESULTS

The most frequent forms of NBF were bone sclerosis and osteophyte. Spur and periosteal NBF were less common, and ankylosis was rare. On both XR and CT, joints with bone erosion were more likely to have NBF; for CT, if erosion was present, the odds ratios (OR) was 45.1 for spur, 3.3 for osteophyte, 16.6 for periosteal NBF, 26.6 for ankylosis and 32.3 for sclerosis, P for all < 0.01. Similarly, on CT, joints with intraosseous tophus were more likely to have NBF; if tophus was present, the OR was 48.4 for spur, 3.3 for osteophyte, 14.5 for periosteal NBF, 35.1 for ankylosis and 39.1 for sclerosis; P for all < 0.001.

CONCLUSIONS

This detailed quantitative analysis has demonstrated that NBF occurs more frequently in joints affected by other features of gout. This work suggests a connection between bone loss, tophus, and formation of new bone during the process of joint remodelling in gout.

Update on research and future directions of the OMERACT MRI inflammatory arthritis group

The OMERACT Magnetic Resonance Imaging (MRI) Task Force has developed and evolved the psoriatic arthritis MRI score (PsAMRIS) over the last few years, and at OMERACT 10, presented longitudinal evaluation by multiple readers, using PsA datasets obtained from extremity MRI magnets. Further evaluation of this score will require more PsA imaging datasets. As well, due to improved image resolution since the development of the original rheumatoid arthritis MRI scoring system (RAMRIS), the Task Force has worked on semiquantitative assessment of joint space narrowing, and developed a reliable method as a potential RAMRIS addendum, although responsiveness will need to be evaluated. One of the strengths of MRI is the ability to detect subclinical synovitis, so the group worked on obtaining low disease activity/clinical remission datasets from a number of international centers and presented cross-sectional findings. Subsequent longitudinal evaluation of this unique resource will be a major continuing focus for the group.

Effects of skim milk powder enriched with glycomacropeptide and G600 milk fat extract on frequency of gout flares: a proof-of-concept randomised controlled trial

OBJECTIVES

Previous laboratory studies have identified two dairy fractions, glycomacropeptide (GMP) and G600 milk fat extract (G600), with anti-inflammatory effects in models of acute gout. The aim of this proof-of-concept clinical trial was to test the hypothesis that daily intake of skim milk powder (SMP) enriched with GMP and G600 can prevent gout flares.

METHODS

This was a 3-month randomised double-blind controlled trial of milk products for prevention of gout flares. One hundred and twenty patients with recurrent gout flares were randomised to one of three arms: lactose powder control, SMP control and SMP enriched with GMP and G600 (SMP/GMP/G600). The primary end point was change in the frequency of gout flares using a daily flare diary measured monthly for 3 months.

RESULTS

The frequency of gout flares reduced in all three groups over the 3-month study period compared with baseline. Over the 3-month study period there was a significantly greater reduction in gout flares in the SMP/GMP/G600 group (analysis of covariance p(group)=0.031, Tukey post hoc test compared with lactose control, p=0.044). Following treatment with SMP/GMP/G600 over the 3-month period, greater improvements were also observed in pain and fractional excretion of uric acid, with trends to greater improvement in tender joint count. Similar adverse event rates and discontinuation rates were observed between the three groups.

CONCLUSIONS

This is the first reported controlled trial of dietary intervention in patients with gout, and suggests that SMP enriched with GMP and G600 may reduce the frequency of gout flares.

Serum urate in chronic gout--will it be the first validated soluble biomarker in rheumatology?

OBJECTIVE

To summarize evidence for and endorsement of serum urate (SU) as having fulfilled the OMERACT filter as a soluble biomarker in chronic gout at the 2010 Outcome Measures in Rheumatology Meeting (OMERACT 10).

METHODS

Data were presented to support the use of SU as a soluble biomarker in chronic gout and specifically the ability to utilize it to predict future patient-reported outcomes.

RESULTS

SU was accepted as having fulfilled the OMERACT filter by 78% of voters. However, consensus was not obtained regarding its use as a soluble biomarker in chronic gout. Although the majority of the criteria for a soluble biomarker were fulfilled, the key criterion of association of the biomarker with outcomes was not agreed upon. It was agreed that the appropriate choice of endpoint must be linked to its clinical importance to the individual with the disorder and its temporal relationship to the intervention. Appropriate outcomes in chronic gout may therefore include gout flares, reduction in tophi, and patient-reported outcomes.

CONCLUSION

SU is a critical outcome measure. It has the potential to fulfil criteria for a soluble biomarker. Further analyses of existing data from randomized controlled trials will be required to determine whether SU can predict future important outcomes, in particular disability.

Tophus measurement as an outcome measure for clinical trials of chronic gout: progress and research priorities

Despite the recognition that tophus regression is an important outcome measure in clinical trials of chronic gout, there is no agreed upon method of tophus measurement. A number of methods have been used in clinical trials of chronic gout, from simple physical measurement techniques to more complex advanced imaging methods. This article summarizes methods of tophus measurement and discusses their properties. Physical measurement using Vernier calipers meets most aspects of the Outcome Measures in Rheumatology (OMERACT) filter. Rigorous testing of the complex methods, particularly with respect to reliability and sensitivity to change, is needed to determine the appropriate use of these methods. Further information is also required regarding which method of physical measurement is best for use in future clinical trials. The need to develop and test a patient-reported outcome measure of tophus burden is also highlighted.

Imaging in gout--what can we learn from MRI, CT, DECT and US?

There are many exciting new applications for advanced imaging in gout. These modalities employ multiplanar imaging and allow computerized three-dimensional rendering of bone and joints (including tophi) and have the advantage of electronic data storage for later retrieval. High-resolution computed tomography has been particularly helpful in exploring the pathology of gout by investigating the relationship between bone erosions and tophi. Magnetic resonance imaging and ultrasonography can image the inflammatory nature of gouty arthropathy, revealing synovial and soft tissue inflammation, and can provide information about the composition and vascularity of tophi. Dual-energy computerized tomography is a new modality that is able to identify tophi by their chemical composition and reveal even small occult tophaceous deposits. All modalities are being investigated for their potential roles in diagnosis and could have important clinical applications in the patient for whom aspiration of monosodium urate crystals from the joint is not possible. Imaging can also provide outcome measures, such as change in tophus volume, for monitoring the response to urate-lowering therapy and this is an important application in the clinical trial setting.

Development and preliminary validation of a magnetic resonance imaging joint space narrowing score for use in rheumatoid arthritis: potential adjunct to the OMERACT RA MRI scoring system

OBJECTIVE

To develop and validate a magnetic resonance imaging (MRI) method of assessment of joint space narrowing (JSN) in rheumatoid arthritis (RA).

METHODS

Phase A: JSN was scored 0-4 on MR images of 5 RA patients and 3 controls at 15 wrist sites and 2nd-5th metacarpophalangeal (MCP) joints by 8 readers (7 once, one twice), using a preliminary scoring system. Phase B: Image review, discussion, and consensus on JSN definition, and revised scoring system. Phase C: MR images of 15 RA patients and 4 controls were scored using revised system by 5 readers (4 once, one twice), and results compared with radiographs [Sharp-van der Heijde (SvdH) method].

RESULTS

Phase A: Intraobserver agreement: intraclass correlation coefficient (ICC) = 0.99; smallest detectable difference (SDD, for mean of readings) = 2.8 JSN units (4.9% of observed maximal score). Interobserver agreement: ICC = 0.93; SDD = 6.4 JSN units (9.9%). Phase B: Agreement was reached on JSN definition (reduced joint space width compared to normal, as assessed in a slice perpendicular to the joint surface), and revised scoring system (0-4 at 17 wrist sites and 2nd-5th MCP; 0: none; 1: 1-33%; 2: 34-66%; 3: 67-99%; 4: ankylosis). Phase C: Intraobserver agreement: ICC = 0.90; SDD = 6.8 JSN units (11.0%). Interobserver agreement: ICC = 0.92 and SDD = 6.2 JSN units (8.7%). The correlation (ICC) with the SvdH radiographic JSN score of the wrist/hand was 0.77. Simplified approaches evaluating fewer joint spaces demonstrated similar reliability and correlation with radiographic scores.

CONCLUSION

An MRI scoring system of JSN in RA wrist and MCP joints was developed and showed construct validity and good intra- and interreader agreements. The system may, after further validation in longitudinal data sets, be useful as an outcome measure in RA.

Patient-reported outcomes in chronic gout: a report from OMERACT 10

OBJECTIVE

To summarize the endorsement of measures of patient-reported outcome (PRO) domains in chronic gout at the 2010 Outcome Measures in Rheumatology Meeting (OMERACT 10).

METHODS

During the OMERACT 10 gout workshop, validation data were presented for key PRO domains including pain [pain by visual analog scale (VAS)], patient global (patient global VAS), activity limitation [Health Assessment Questionnaire-Disability Index (HAQ-DI)], and a disease-specific measure, the Gout Assessment Questionnaire version 2.0 (GAQ v2.0). Data were presented on all 3 aspects of the OMERACT filters of truth, discrimination, and feasibility. One PRO, health-related quality of life measurement with the Medical Outcomes Study Short-form 36 (SF-36), was previously endorsed at OMERACT 9.

RESULTS

One measure for each of the 3 PRO of pain, patient global, and activity limitation was endorsed by > 70% of the OMERACT delegates to have appropriate validation data. Specifically, pain measurement by VAS was endorsed by 85%, patient global assessment by VAS by 73%, and activity limitation by HAQ-DI by 71%. GAQ v2.0 received 30% vote and was not endorsed due to several concerns including low internal consistency and lack of familiarity with the measure. More validation studies are needed for this measure.

CONCLUSION

With the endorsement of one measure each for pain, patient global, SF-36, and activity limitation, all 4 PRO for chronic gout have been endorsed. Future validation studies are needed for the disease-specific measure, GAQ v2.0. Validation for PRO for acute gout will be the focus of the next validation exercise for the OMERACT gout group.

Monosodium urate monohydrate crystals inhibit osteoblast viability and function: implications for development of bone erosion in gout

BACKGROUND

Bone erosion is a common manifestation of chronic tophaceous gout.

OBJECTIVES

To investigate the effects of monosodium urate monohydrate (MSU) crystals on osteoblast viability and function.

METHODS

The MTT assay and flow cytometry were used to assess osteoblast cell viability in the MC3T3-E1 and ST2 osteoblast-like cell lines, and primary rat and primary human osteoblasts cultured with MSU crystals. Quantitative real-time PCR and von Kossa stained mineralised bone formation assays were used to assess the effects of MSU crystals on osteoblast differentiation using MC3T3-E1 cells. The numbers of osteoblasts and bone lining cells were quantified in bone samples from patients with gout.

RESULTS

MSU crystals rapidly reduced viability in all cell types in a dose-dependent manner. The inhibitory effect on cell viability was independent of crystal phagocytosis and was not influenced by differing crystal length or addition of serum. Long-term culture of MC3T3-E1 cells with MSU crystals showed a reduction in mineralisation and decreased mRNA expression of genes related to osteoblast differentiation such as Runx2, Sp7 (osterix), Ibsp (bone sialoprotein), and Bglap (osteocalcin). Fewer osteoblast and lining cells were present on bone directly adjacent to gouty tophus than bone unaffected by tophus in patients with gout.

CONCLUSIONS

MSU crystals have profound inhibitory effects on osteoblast viability and differentiation. These data suggest that bone erosion in gout occurs at the tophus-bone interface through alteration of physiological bone turnover, with both excessive osteoclast formation, and reduced osteoblast differentiation from mesenchymal stem cells.

Measuring bone erosion and edema in rheumatoid arthritis: a comparison of manual segmentation and RAMRIS methods

PURPOSE

To investigate the reliability, feasibility, and validity of a computer-assisted manual segmentation (outlining) technique for measuring magnetic resonance imaging (MRI) bone erosion and edema at the wrist in rheumatoid arthritis (RA).

MATERIALS AND METHODS

The 3T MRI scans were obtained in 22 RA patients (<2 years). Bone erosion and edema volumes were scored by two readers using outlining and were compared with RAMRIS scores.

RESULTS

Using outlining, intraobserver reliability for erosions and edema was high: intraclass correlation coefficients (ICCs) = 0.994 (0.991, 0.997) and 0.996 (0.994, 0.998), respectively (Reader 1). Interobserver reliability was high for bone erosion (ICC [90% confidence interval, CI] = 0.80 [0.64, 0.92]) and comparable to RAMRIS scoring (ICC 0.78 [0.64, 0.92]), but was only moderate for bone edema (0.46 [0.00, 0.96]), compared with RAMRIS (ICC = 0.84 [0.73, 0.94]). The methods were highly correlated for erosion scores, r = 0.90, 0.82 (Readers 1 and 2) and moderately correlated for edema, r = 0.57, 0.87.

CONCLUSION

Segmentation (outlining) can be used to measure the volume of MRI bone erosion and edema at the wrist in RA patients. When compared with RAMRIS scoring, outlining had similar reliability for quantifying erosions but reliability was lower for bone edema, possibly reflecting difficulty delineating the borders of affected bone.

Methods of tophus assessment in clinical trials of chronic gout: a systematic literature review and pictorial reference guide

Objective

To identify methods of tophus measurement for gout studies, summarise the properties of these methods and compile a detailed pictorial reference guide to demonstrate the methods.

Methods

A systematic search strategy for methods of tophus measurement was formulated. For each method, papers were assessed by two reviewers to summarise information according to the specific components of the Outcomes Measures in Rheumatology (OMERACT) filter: feasibility, truth and discrimination. Detailed images were obtained to construct the reference guide.

Results

Eight methods of tophus measurement were identified: counting the total number of tophi, physical measurement using tape measure, physical measurement using Vernier callipers, digital photography, ultrasonography (US), MRI, CT and dual energy CT. Feasibility aspects of the methods are well documented. Physical measurement techniques are more feasible than advanced imaging methods, but do not allow for assessment of intra-articular tophi or for data storage and central reading. The truth aspect of the filter has been documented for many methods, particularly Vernier callipers, US, MRI and CT. Reliability of most methods has been reported as very good or excellent. Sensitivity to change has been reported for all methods except MRI and CT.

Conclusion

A variety of methods of tophus assessment have been described for use in clinical trials of chronic gout. Physical measurement techniques (particularly the Vernier calliper method) and US measurement of tophus size appear to meet most aspects of the OMERACT filter.

Functional and biomechanical characteristics of foot disease in chronic gout: A case-control study

OBJECTIVES

despite the predilection of gout to the feet, the impact of gout on foot function and biomechanics is currently unknown. The aim of this study was to describe the effects of chronic gout upon function and selected biomechanical parameters associated with gait.

METHODS

twenty-five patients with a history of gout were compared with 25 age and gender matched control participants with no history of gout or other forms of arthritis. General function, foot specific disease activity and lower limb activities were determined using the Health Assessment Questionnaire, Foot Function Index (pain domain), and Leeds Foot Impact Scale respectively. Each patient also underwent a gait assessment that included plantar pressure measurements and an evaluation of temporal-spatial gait parameters.

FINDINGS

patients with chronic gout had higher levels of general and foot-specific disability, pain and impairment (P ≤0.001). Significantly lower peak plantar pressures were observed in the hallux of patients with chronic gout (P ≤0.05). Significantly higher pressure-time integrals were observed in the cases at the midfoot (P ≤0.05), but lower values were observed at the hallux (P ≤0.05). Patients with chronic gout walked slower, with longer step and stride lengths compared to the controls.

INTERPRETATION

patients with chronic gout experience pain and disability associated with their feet. Different toe-off strategies may account for functional changes and pain associated with foot problems in chronic gout.

Circulating mediators of bone remodeling in psoriatic arthritis: implications for disordered osteoclastogenesis and bone erosion

Introduction

Diverse bone pathologies are observed in patients with psoriatic arthritis (PsA). Uncoupling of bone remodeling with disordered osteoclastogenesis has been implicated in the pathogenesis of PsA. The aim of this study was to examine the role of soluble mediators of bone remodeling within the circulation of patients with PsA.

Methods

Patients with PsA (n = 38), with psoriasis (n = 10), and healthy controls (n = 12) were studied. Serum was obtained for testing of Dikkopf-1 (Dkk-1), macrophage-colony stimulating factor (M-CSF), osteoprotegerin (OPG), and receptor activator of nuclear factor-κB ligand (RANKL) with ELISA. Patients with PsA also had bone densitometry, plain radiographs of the hands and feet, and assessment of peripheral blood osteoclast precursors. Radiographs were scored for erosion, joint-space narrowing, osteolysis, and new bone formation.

Results

Compared with those with psoriasis and healthy controls, patients with PsA had higher circulating concentrations of Dkk-1 and M-CSF. In patients with PsA, M-CSF and RANKL, but not Dkk-1, concentrations positively correlated with radiographic erosion, joint-space narrowing, and osteolysis scores. Mediators of bone remodeling did not correlate with the number of joints with new bone formation or with total hip-bone mineral density. Peripheral blood CD14⁺/CD11b⁺ cells, and the number of osteoclast-like cells and resorptive pits after culture with RANKL and M-CSF also correlated with radiographic damage scores. Circulating M-CSF concentrations correlated with the percentage of peripheral blood CD14⁺/CD11b⁺ cells.

Conclusions

Systemic expression of soluble factors that promote osteoclastogenesis is disordered in patients with PsA and may contribute to periarticular bone loss in this disease.

Cellular characterization of the gouty tophus: a quantitative analysis

OBJECTIVE

To characterize the cellular architecture of the tophus and to determine the presence of cytokines implicated in the initiation and resolution of gouty inflammation.

METHODS

Sixteen fixed, paraffin-embedded, uninfected tophus samples were surgically obtained from 12 patients with microscopically proven gout and were analyzed by quantitative immunohistochemistry. The number of cells present in the corona and fibrovascular zones of the tophus was analyzed by Genmod mixed models analysis.

RESULTS

Numerous CD68+ mononucleated and multinucleated cells were present within the corona zone. Mast cells were identified in all tophus samples and at similar densities throughout the corona and fibrovascular zones. In contrast, neutrophils were rarely observed. Plasma cells were present in very high numbers within the corona zone. The overall number of CD20+ B cells was much lower. However, in 6 of 12 patients (50%), at least 1 B cell aggregate was present in the fibrovascular zone. Large numbers of cells expressing interleukin-1beta (IL-1beta) were observed in the corona zone. Transforming growth factor beta1 (TGFbeta1)-expressing mononucleated cells were also identified. The number of CD68+ cells correlated with the number of cells expressing IL-1beta (r = 0.691, P = 0.009) and the number expressing TGFbeta1 (r = 0.518, P = 0.04).

CONCLUSION

The tophus represents a complex and organized chronic inflammatory tissue response to monosodium urate monohydrate crystals involving both innate and adaptive immune cells. The coexpression of IL-1beta and TGFbeta1 suggests that both proinflammatory and antiinflammatory factors present within the tophus contribute to a cycle of chronic inflammation, attempted resolution, and tissue remodeling.

Acute effect of milk on serum urate concentrations: a randomised controlled crossover trial

OBJECTIVES

Recent observational studies have highlighted the beneficial role of dairy ingestion in gout prevention. The aims of this study were to determine the acute effects of milk ingestion on serum urate concentrations and examine the mechanisms of these effects.

METHODS

This was a short-term randomised controlled crossover trial of milk in 16 healthy male volunteers. The following products were tested (each 80 g protein): soy control, early season skim milk, late season skim milk (containing high concentrations of orotic acid, a naturally occurring uricosuric agent) and ultrafiltrated MPC 85 skim milk. Each participant received a single dose of each product in random order. Serum and urine were obtained immediately before and then hourly over a 3 h period after ingestion of each study product.

RESULTS

Ingestion of the soy control led to an increase in serum urate concentrations by approximately 10%. In contrast, ingestion of all milks led to a decrease in serum urate concentrations by approximately 10% (p<0.0001). All products (including soy) rapidly increased the fractional excretion of uric acid (FEUA). Late season milk led to a greater increase in FEUA than MPC 85 (p=0.02) and early season milk (p=0.052). There were no differences over time in serum oxypurines or purine-containing nucleosides. However, all products increased the fractional excretion of xanthine.

CONCLUSIONS

Intact milk has an acute urate-lowering effect. These data provide further rationale for long-term intervention studies to determine whether such dietary interventions have an adjunctive role in the management of individuals with hyperuricaemia and gout.

Reducing invasiveness, duration, and cost of magnetic resonance imaging in rheumatoid arthritis by omitting intravenous contrast injection -- Does it change the assessment of inflammatory and destructive joint changes by the OMERACT RAMRIS?

OBJECTIVE

Gadolinium (Gd)-enhanced magnetic resonance imaging (MRI) provides highly sensitive assessment of inflammatory and destructive changes in rheumatoid arthritis (RA) joints, but intravenous (IV) Gd injection prolongs examination time and increases cost, invasiveness, and patient discomfort. We explored to what extent RA joint pathologies in wrists and metacarpophalangeal (MCP) joints can be reliably assessed by unenhanced MRI images compared with Gd-enhanced MRI as the reference method.

METHODS

MRI data sets from 2 RA substudies were scored according to preliminary OMERACT RA MRI scoring system (RAMRIS): Substudy A included 1.0 T/1.5 T MR images from 40 RA patients, which were scored twice by 2 experienced readers. Substudy B included 0.2 T dedicated extremity MRI (E-MRI) images from 55 patients, scored twice by one experienced reader. The first reading included only unenhanced images, whereas complete image sets were available for the second reading.

RESULTS

Gd contrast injection appeared unimportant to MRI scores of bone erosions and bone edema in RA wrist and MCP joints. However, when post-Gd MRI was considered the standard reference, MRI without Gd provided only moderate to high agreement concerning assessment of synovitis, and omitting the post-Gd acquisitions increased the interreader variation on synovitis scores. Low-field (0.2 T) E-MRI in these exercises provided a lower sensitivity of unenhanced imaging for synovitis than MRI using higher-field strengths.

CONCLUSION

Omitting IV contrast injection did not change scores of bone erosions and bone edema, but decreased the reliability of synovitis scores. However, this disadvantage may for some purposes be outweighed by the possibility to assess more joints and/or greater feasibility.

Predicting joint damage in rheumatoid arthritis using MRI scanning

Predicting prognosis in the patient with newly diagnosed rheumatoid arthritis is of key importance so that high-cost therapies can be tailored to the needs of the individual. In a recent issue of Arthritis Research and Therapy, the prognostic significance of MRI changes at the forefoot has been studied. While progression to radiographic erosion occurred rarely in this group of patients exposed to potent disease-suppressing therapies, including TNF inhibitors, MRI bone edema, representing osteitis, has been further implicated as a forerunner to bone erosion. Early MRI scans of the forefoot were helpful in defining those with the potential to progress as well as those in a good prognosis category.

Identification of dairy fractions with anti-inflammatory properties in models of acute gout

AIMS

Large epidemiological studies have shown that low-fat dairy intake reduces the risk of developing gout. It was hypothesised that factors within dairy fractions inhibit the inflammatory response to monosodium urate monohydrate (MSU) crystals.

METHODS

Dairy fractions were tested in MSU crystal-stimulated THP-1 cell assays. Fractions with inhibitory effects were then tested in the murine urate peritonitis model.

RESULTS

Two dairy fractions were found to have consistent inhibitory effects. Glycomacropeptide (GMP) and G600 milk fat extract both inhibited interleukin-1beta (IL1beta) gene and protein expression in the THP-1 cell assay. Conversely, standard milk fat increased IL8 protein expression in the THP-1 cell assay. Oral administration of GMP and G600 milk fat extract inhibited cellular influx in the urate peritonitis model.

CONCLUSIONS

Both protein and lipid fractions within dairy products are capable of modulating the inflammatory response to MSU crystals.

Will Jill come tumbling after? The case for a JAK2-type mutation as a prequel to the connective tissue disorders

The JAK2 [V617F] mutation has recently been recognised as critical to the pathogenesis of the myeloproliferative disorders (MPDs). Thus, a common mutation affecting a haematopoietic precursor stem cell is capable of giving rise to diverse clinical phenotypes. In this hypothesis paper, we propose that a similar mutation affecting a stem cell precursor, most likely of the B cell lineage, could underlie the development of the connective tissue disorders which could be regarded as "lymphoproliferative" disorders. Consistent with this hypothesis is the observation that there are similarities between the myeloproliferative disorders and the connective tissue disorders in terms of their biological behaviour. Diseases within each family can transform into each other and sometimes into haematological malignancies (most often B cell origin non-Hodgkins lymphoma for the connective tissue disorders and acute myeloid leukemia for the myeloproliferative disorders). The timecourse for development of the connective tissue disorders involves a long latent period when autoantibodies are present (anti-CCP and ANA) possibly reflecting production by a B cell clone. A similar time-dependent increase in clonal dominance has been described in erythroblastic clones taken from the bone marrow of polycythemia vera patients, long before the onset of clinical disease. Evidence of B cell clonality has been described in bone marrow samples from rheumatoid arthritis patients and from glandular biopsies from those with Sjogren's syndrome. Moreover, pseudofollicles containing activated B cells are features of rheumatoid synovial membrane and have also recently been described in subchondral bone where they are associated with macrophages, T cells and osteoclasts. The success of B cell depletion therapy in rheumatoid arthritis and systemic lupus erythematosus is also strong circumstantial evidence for this hypothesis.

The MRI view of synovitis and tenosynovitis in inflammatory arthritis: implications for diagnosis and management

MRI scanning is the current gold standard modality for imaging synovitis and tenosynovitis in patients with inflammatory arthritis. Inflamed synovial membrane within the joints and investing tendon sheaths appears thickened on T1-weighted sequences and enhances postcontrast. On T2-weighted sequences, synovitis and synovial effusions typically show a high signal. Studies have shown correlations between the degree of inflammation and vascularity of synovium obtained at biopsy and postcontrast enhancement on matching dynamic MRI scans. Scoring systems have been devised that are based on quantifying synovial membrane thickening and signal intensity on static postcontrast scans and have been validated in multireader settings. Moderate to high reliability has been demonstrated with trained readers and quantification of synovitis in this way is being used increasingly as an outcome measure in clinical trials to assess response to therapy. MRI-observed synovitis is almost invariable in those with active rheumatoid arthritis, but recent studies have also demonstrated its presence in patients in clinical remission, emphasizing the sensitivity of this technique and the importance of subclinical joint inflammation. MRI-observed synovitis has been validated against other imaging modalities, including power Doppler ultrasound, and has also been investigated in normal subjects (where mild enhancement can rarely occur). Studies over 1-2 years have suggested that MRI synovial membrane volume and postcontrast enhancement on dynamic imaging can predict the development of erosions. In the long term, an overall score of inflammation incorporating synovitis, tenosynovitis, and bone edema may be a more useful MRI predictor of aggressive erosive disease.