The value of contrast-enhanced color Doppler ultrasound in the detection of vascularization of finger joints in patients with rheumatoid arthritis

OBJECTIVE: A prospective study was performed to assess the usefulness of contrast-enhanced color Doppler ultrasound (CDUS) in the evaluation of intraarticular vascularization of finger joints in patients with rheumatoid arthritis (RA). METHODS: We investigated 198 finger joints in 46 patients with RA, and 80 finger joints in 10 healthy volunteers. Joints with varying levels of clinical activity of inflammation were classified as being active, moderately active, or inactive. CDUS was performed with a high-frequency multi-D linear array transducer. A microbubble-based ultrasound (US) contrast agent (Levovist; Schering, Berlin, Germany) was intravenously infused. Doppler findings were rated on the basis of both unenhanced and contrast-enhanced CDUS images. RESULTS: Healthy joints showed no intraarticular vascularization on either unenhanced or contrast-enhanced CDUS. Unenhanced CDUS detected intraarticular vascularization in 7 (8%) of 83 inactive joints, in 31 (52%) of 60 moderately active joints, and in 32 (58%) of 55 active joints. Contrast-enhanced CDUS detected intraarticular vascularization in 41 (49%) of 83 joints with inactive RA, in 59 (98%) of 60 joints with moderately active RA, and in all 55 joints with active RA. Detection of intraarticular vascularization was improved by administration of the microbubble-based US contrast agent (P < 0.001). Contrast-enhanced CDUS demonstrated differences in intraarticular vascularization between joints with inactive RA and those with active RA (P < 0.001), between joints with inactive RA and those with moderately active RA (P < 0.001), and between joints with moderately active RA and those with active RA (P < 0.001). CONCLUSION: The use of a microbubble-based US contrast agent significantly improved the detection of intraarticular vascularization in the finger joints of patients with RA. This technique seems to be a useful adjunct in the assessment of disease activity.     

Inflammatory low back pain: High negative predictive value of contrast‐enhanced color Doppler ultrasound in the detection of inflamed sacroiliac joints

Objective

To determine the value of microbubble contrast agents for color Doppler ultrasound (CDUS) compared with magnetic resonance imaging (MRI) in the detection of active sacroiliitis.

Methods

An observational case‐control study of 103 consecutive patients (206 sacroiliac [SI] joints) with inflammatory low back pain according to the Calin criteria and 30 controls (60 SI joints) without low back pain was conducted at the University Hospital of Innsbruck. All patients and controls underwent unenhanced and contrast‐enhanced CDUS and MRI of the SI joints. Sensitivity, specificity, positive predictive value (PPV), and negative predictive value (NPV) of unenhanced and contrast‐enhanced CDUS were evaluated.

Results

Forty‐three patients (41%) with 70 of 206 SI joints (34%) and none of the controls nor the 60 control SI joints demonstrated active sacroiliitis on MRI. Unenhanced CDUS showed a sensitivity of 17%, a specificity of 96%, a PPV of 65%, and an NPV of 72%; contrast‐enhanced CDUS showed a sensitivity of 94%, a specificity of 86%, a PPV of 78%, and an NPV of 97%. Detection of vascularity in the SI joint was increased by contrast administration (P < 0.0001). Clustered receiver operating curve analysis demonstrated that enhanced CDUS (A_z = 0.89) was significantly better than unenhanced CDUS (A_z = 0.61) for the diagnosis of active sacroiliitis verified by MRI (P < 0.0001; 2‐sided test).

Conclusion

Microbubble contrast‐enhanced CDUS is a sensitive technique with a high NPV for detection of active sacroiliitis compared with MRI.

     

Microbubble‐enhanced ultrasound exposure promotes uptake of methotrexate into synovial cells and enhanced antiinflammatory effects in the knees of rabbits with antigen‐induced arthritis

Objective

To evaluate whether microbubble‐enhanced ultrasound (US) treatment promotes the delivery of methotrexate (MTX) into synovial cells and the enhanced antiinflammatory effects of intraarticular MTX therapy in a rabbit arthritis model.

Methods

Arthritis was induced in both knees of 53 rabbits by immunization with ovalbumin. MTX including a microbubble agent was then injected into the left and right knee joints, and the right knees were exposed to US (MTX+/US+ group), while the left knees were not (MTX+/US− group). The knee joints were evaluated histologically in 7 rabbits at 5 time points up to day 56. Quantitative gene expression of interleukin‐1β (IL‐1β) in synovial tissue was measured on days 7 and 28. Eight rabbits were used for the measurement of MTX concentration in synovial tissue 12 hours after treatment. To evaluate the effect of microbubble‐enhanced US treatment in the absence of MTX, only the microbubble agent was injected into the left and right knee joints of 10 rabbits with or without US exposure, and these animals were evaluated histologically on days 7 and 28.

Results

The MTX concentration in synovial tissue was significantly higher in the MTX+/US+ group than in the MTX+/US− group. Synovial inflammation was less prominent in the MTX+/US+ group compared with the MTX+/US− group, judging from the results of the histologic evaluation and the gene expression levels of IL‐1β in synovial tissue. It also appeared that microbubble‐enhanced US exposure itself did not affect inflammation.

Conclusion

Microbubble‐enhanced US exposure promoted the uptake of MTX into synovial cells, which resulted in enhancement of the antiinflammatory effects of the intraarticular MTX injection. These results suggest that application of this technique may have clinical benefit.

     

Diagnostic value of high‐resolution B‐mode and doppler sonography for imaging of hand and finger joints in rheumatoid arthritis

Objective

High‐resolution sonography enables a detailed assessment of intraarticular and extraarticular soft tissue abnormalities of joints affected by rheumatoid arthritis (RA). This study was undertaken to evaluate the diagnostic value of B‐mode sonography and power Doppler compared with that of clinical examinations and conventional radiography.

Methods

The study group comprised 47 patients (14 men, 33 women) with different grades of RA; 31 patients were rheumatoid factor (RF) positive, and 16 were RF negative. The wrists, first through fifth metacarpophalangeal joints, and second through fifth proximal interphalangeal joints of these patients were scored with ultrasound in B‐mode and power Doppler application, using a standardized technique. Involvement and severity of inflammation, as well as vascularization, were scored according to a new 3‐point scale. The results were correlated with benchmarks of the clinical and radiologic investigations. Clinical status and conventional radiologic status were determined according to the Disease Activity Score and the Larsen score.

Results

After preliminary studies in 15 patients, 39% of 704 joints were found to be abnormal by clinical investigation. Erosions were detected by radiography and sonography in 23% and 43% of joints, respectively. Hypervascularization was observed in 34% of 704 joints by power Doppler application. There was a significant correlation (P < 0.001) between the different methods for the detection of the severity of lesions. Use of a modern, state‐of‐the‐art power Doppler program was necessary for semiquantification, and a standardized investigation technique and scoring system provided sufficient quality measures.

Conclusion

Sonography detects 20% more abnormalities than does radiography, and sonography has the potential to provide simple grading of disease activity. The rate of detection of abnormalities was slightly higher with clinical examination compared with sonography.

     

Ablation of the Ccr2 gene exacerbates polyarthritis in interleukin‐1 receptor antagonist–deficient mice

Objective

The pathogenesis of rheumatoid arthritis (RA) involves cytokines and chemokines. Given the role of intraarticular macrophage infiltration in RA, this study was undertaken to address the pathogenic role of CCR2, a chemokine receptor that is abundantly expressed by macrophages, in Il1rn‐deficient mice, a mouse model of RA.

Methods

Il1rn‐deficient and Il1rn and Ccr2–double‐deficient mice were subjected to clinical assessment of arthritis and histologic examination. Bone mineral density was measured with computed tomography. The types of cells infiltrating joints were determined by immunohistochemical analysis and flow cytometric analysis. Osteoclasts in joints were quantified after tartrate‐resistant acid phosphatase staining. Cytokine and chemokine levels were measured by enzyme‐linked immunosorbent assay and multiplex suspension array assay. The expression patterns of chemokines and osteoclastogenic factors were determined by double‐color immunofluorescence analysis. Anti‐mouse CXCR2 antibody was injected into Il1rn and Ccr2–double‐deficient mice for blocking experiments.

Results

Ablation of the Ccr2 gene actually exacerbated arthritis and intraarticular osteoclastogenesis, while it enhanced intraarticular neutrophil but not macrophage accumulation in Il1rn‐deficient mice. Infiltrated neutrophils expressed the osteoclastogenic factors RANKL and ADAM‐8, thereby augmenting intraarticular osteoclastogenesis in Il1rn and Ccr2–double‐deficient mice. Moreover, the double‐deficient mice exhibited enhanced expression of the neutrophilic chemokines keratinocyte chemoattractant and macrophage inflammatory protein 2 (MIP‐2), compared with Il1rn‐deficient mice. Finally, neutralizing antibodies to CXCR2, the receptor for keratinocyte chemoattractant and MIP‐2, dramatically attenuated arthritis in Il1rn and Ccr2–double‐deficient mice.

Conclusion

Our findings indicate that CCR2‐mediated signals can modulate arthritis in Il1rn‐deficient mice by negatively regulating neutrophil infiltration.

     

Dynamic gadolinium‐enhanced magnetic resonance imaging of the wrist in patients with rheumatoid arthritis can discriminate active from inactive disease

Objective

To determine the efficacy of dynamic gadolinium‐enhanced magnetic resonance imaging (MRI) of the wrist in the evaluation of disease activity in patients with rheumatoid arthritis (RA).

Methods

Thirty‐six patients with RA (with different degrees of disease activity) and 5 healthy controls were studied. MRI was performed with a low‐field (0.2T), extremity‐dedicated machine. After an intravenous bolus injection of gadolinium–diethylenetriamine pentaacetic acid, 20 consecutive fast spin‐echo images of 3 slices of the wrist were obtained every 18 seconds.

Results

The curves of synovial membrane enhancement identified the following 2 groups: controls and RA patients in remission, and RA patients with active or intermediately active disease. Both the rate of early enhancement (REE) and relative enhancement (RE) were significantly higher in patients with active RA than in those with inactive RA and controls. The REE and RE were significantly correlated with the number of swollen joints (P < 0.00001 and P = 0.003, respectively), the number of tender joints (P < 0.00001 and P = 0.004, respectively), the Ritchie index (P = 0.0002 for both REE and RE), the Disease Activity Score (P = 0.0004 and P = 0.0008, respectively), the Health Assessment Questionnaire (HAQ) (P = 0.0002 and P = 0.0007, respectively), early morning stiffness (P = 0.001 and P = 0.009, respectively), the C‐reactive protein level (P = 0.015 and P = 0.03, respectively), the erythrocyte sedimentation rate (P = 0.03, RE only), and α2 globulins (P = 0.036 and P = 0.028, respectively).

Conclusion

Our data support use of dynamic MRI for discriminating active from inactive RA. Enhancement curves are associated not only with laboratory and clinical indicators of inflammation, but also with the HAQ, a relevant predictor of RA functional outcome. This technique can be repeated frequently and is an excellent candidate for the ideal method for the followup of patients with RA.

     

Amelioration of collagen‐induced arthritis in rats by nanogold

Objective

Angiogenesis plays a part in the pathogenesis of rheumatoid arthritis (RA), and nanogold inhibits the activity of an angiogenic factor, vascular endothelial growth factor (VEGF). We therefore investigated whether intraarticular delivery of nanogold ameliorates collagen‐induced arthritis (CIA) in rats.

Methods

Binding of 13‐nm nanogold to VEGF in human RA synovial fluid (SF) and its effects on RA SF–induced endothelial cell proliferation and migration were assessed. Nanogold was administered intraarticularly to rats with CIA before the onset of arthritis. Progression of CIA was monitored by measures of clinical, radiologic, and histologic changes. In addition, the microvessel density and extent of infiltrating macrophages as well as levels of tumor necrosis factor α (TNFα) and interleukin‐1β (IL‐1β) in the ankle joints were determined.

Results

Nanogold bound to VEGF in RA SF, resulting in inhibition of RA SF–induced endothelial cell proliferation and migration. Significant reductions in ankle circumference, articular index scores, and radiographic scores were observed in the nanogold‐treated rats with CIA compared with their control counterparts. In addition, the histologic score (of synovial hyperplasia, cartilage erosion, and leukocyte infiltration), microvessel density, macrophage infiltration, and levels of TNFα and IL‐1β were also significantly reduced in the ankle joints of nanogold‐treated rats.

Conclusion

Our results are the first to demonstrate that intraarticular administration of nanogold ameliorates the clinical course of CIA in rats. Nanogold exerted antiangiogenic activities and subsequently reduced macrophage infiltration and inflammation, which resulted in attenuation of arthritis. These results demonstrate proof of principle for the use of nanogold as a novel therapeutic agent for the treatment of RA.

     

Complement activation in patients with rheumatoid arthritis mediated in part by C‐reactive protein

Objective

Complement activation in patients with rheumatoid arthritis (RA) is considered to be triggered by immune complexes. Recently, it was shown that C‐reactive protein (CRP) can activate the complement system in vivo. We therefore hypothesized that part of the complement activation in RA is due to CRP. The aim of this study was to investigate CRP‐mediated complement activation in RA, and to assess its correlation with disease activity.

Methods

Complexes between CRP and the activated complement components C3d (C3d–CRP) and C4d (C4d–CRP), which reflect CRP‐mediated complement activation, as well as the overall levels of activated C3 and C4 were measured in the plasma of 107 patients with active RA and 177 patients with inactive RA. Inactive RA was defined according to the American College of Rheumatology criteria for clinical remission. Disease activity was assessed by the modified Disease Activity Score (DAS28).

Results

Plasma levels of C3d–CRP and C4d–CRP were increased in the majority of the patients, and were significantly higher in patients with active disease versus those with inactive RA (P < 0.001). In patients with active RA, the plasma concentrations of C3d–CRP and C4d–CRP correlated significantly with the DAS28 (Spearman's rho 0.61 and 0.55, respectively; P < 0.001), whereas these correlations were less pronounced in patients with inactive RA (Spearman's rho 0.28 [P < 0.001] and 0.25 [P = 0.001], respectively). Levels of activated C3 and C4 were also increased in the majority of the patients, particularly in patients with active RA.

Conclusion

Part of the activation of complement in RA is mediated by CRP and is correlated with disease activity. We suggest that this activation is involved in the pathogenesis of RA.

     

Molecular imaging of cartilage damage of finger joints in early rheumatoid arthritis with delayed gadolinium‐enhanced magnetic resonance imaging

Objective

To assess cartilage glycosaminoglycan content and cartilage thickness in the metacarpophalangeal (MCP) joints of patients with early rheumatoid arthritis (RA) and healthy volunteers.

Methods

After review board approval and informed consent were obtained, 22 subjects were prospectively enrolled (9 patients with early RA [7 women and 2 men with a mean ± SD age of 49 ± 13 years; range 25–68 years] and 13 healthy volunteers [10 women and 3 men with a mean ± SD age of 51 ± 12 years; range 25–66 years). In a total of 44 MCP joints of the index and middle fingers, measurements of cartilage thickness and delayed gadolinium‐enhanced magnetic resonance imaging (MRI) of cartilage (dGEMRIC) index (T1 [msec]) were obtained using the variable flip‐angle method and a 3T MR scanner. MRIs were evaluated for bone edema, erosions, and synovitis (using the RA MRI Scoring criteria). Student's t‐test was used to test the significance of differences between groups.

Results

The mean ± SD dGEMRIC index was 497 ± 86 msec in healthy volunteers and was significantly lower in the early RA group (421 ± 76 msec) (P = 0.042). There was no joint space narrowing seen on standard radiographs. No significant difference was found between cartilage thickness in patients with early RA and that in controls (index finger mean ± SD 1.27 ± 0.23 mm in RA patients versus 1.46 ± 0.34 mm in controls [P = 0.16] and middle finger 1.26 ± 0.23 mm in RA patients versus 0.97 ± 0.47 mm in controls [P = 0.10]). No significant correlation was noted between cartilage thickness and dGEMRIC index (R = 0.36, P = 0.88 in RA patients; R = 0.156, P = 0.445 in controls).

Conclusion

Our findings indicate that cartilage damage is present in the MCP joints of patients with early RA despite the absence of joint space narrowing on standard radiographs and MRI. Cartilage damage in RA can be imaged with dGEMRIC.

     

Role of Crk‐associated substrate lymphocyte type in the pathophysiology of rheumatoid arthritis in tax transgenic mice and in humans

Objective

To investigate the role of Crk‐associated substrate lymphocyte type (Cas‐L), a downstream signaling molecule of β1 integrins, in the pathophysiology of rheumatoid arthritis (RA).

Methods

We analyzed human T lymphotropic virus type I (HTLV‐I) tax transgenic mice as well as samples from human RA patients. Splenocytes from tax transgenic mice were cultured on mouse endothelial cell–covered Transwell inserts, and cells migrating through the endothelial monolayer were counted. Biochemical studies were performed to analyze the protein expression and tyrosine phosphorylation of Cas‐L. Immunohistochemical analysis was performed to detect Cas‐L–positive cells that had infiltrated into the joints.

Results

Migratory activity of splenocytes from tax transgenic mice with arthritis (ATg) was much higher than that of tax transgenic mice without arthritis (NTg) and littermate control mice. The expression of Cas‐L protein and its tyrosine phosphorylation were increased in ATg mice compared with NTg and control mice, and this was accompanied by enhanced autophosphorylation of Fyn and Lck. Immunohistochemical analysis demonstrated a large number of Cas‐L–positive lymphocytes migrating into the affected joints. Furthermore, in human RA, Cas‐L–positive lymphocytes were shown to infiltrate to the inflammatory lesions.

Conclusion

These results strongly suggest that Cas‐L plays an important role in the pathophysiology of RA.

     

Combination treatment with methotrexate,cyclosporine, and intraarticular betamethasone compared with methotrexate and intraarticular betamethasone in early active rheumatoid arthritis: An investigator‐initiated,multicenter, randomized,double‐blind,parallel‐group,placebo‐controlled study

Objective

To investigate whether disease control can be achieved in early active rheumatoid arthritis (RA) by treatment with methotrexate and intraarticular betamethasone, and whether the addition of cyclosporine to the regimen has any additional effect.

Methods

Patients (n = 160) were randomized to receive methotrexate 7.5 mg/week plus cyclosporine 2.5 mg/kg of body weight/day (combination therapy) or methotrexate plus placebo‐cyclosporine (monotherapy). At weeks 0, 2, 4, 6, and 8 and every 4 weeks thereafter, betamethasone was injected into swollen joints (maximum 4 joints or 4 ml per visit). Beginning at week 8, if synovitis was present, the methotrexate dosage was increased stepwise up to 20 mg/week, with a subsequent stepwise increase in the cyclosporine or placebo‐cyclosporine dosage up to 4 mg/kg.

Results

At 52 weeks, 20% improvement according to the American College of Rheumatology criteria (ACR20) was achieved in 85% of the combination therapy group versus 68% of the monotherapy group (P = 0.02). The median individual overall ACR response (ACR‐N) in the 2 groups was 80.0% (interquartile range 40.1–91.8%) and 54.5% (interquartile range 2.4–87.8%), respectively (P = 0.025). At 48 and 52 weeks, ACR remission criteria were met in 35% of the combination therapy group and 28% of the monotherapy group. Progression in the Larsen score at 52 weeks was –0.2 ± 6.5 and 0.4 ± 6.9 (mean ± SD) in the combination therapy and monotherapy groups, respectively. Serum creatinine levels increased by 7%, and hypertrichosis was more prevalent, in the combination therapy group.

Conclusion

Combined treatment with methotrexate and intraarticular glucocorticoid showed excellent disease control and stopped the progression of erosions in patients with early active RA, who had a poor prognosis. Addition of cyclosporine improved the ACR20 and ACR‐N responses, whereas the ACR50 and ACR70 responses, remission rates, and radiographic changes did not differ between the 2 study groups.

     

Comparative study of the detection of joint injury in early-stage rheumatoid arthritis by magnetic resonance imaging of the wrist and finger joints and physical examination

Objective

To verify whether magnetic resonance imaging (MRI)–proven joint injury is sensitive as compared with joint injury determined by physical examination.

Methods

MRI of the wrist and finger joints of both hands was examined in 51 early‐stage rheumatoid arthritis (RA) patients by both plain and gadolinium diethylenetriaminepentaacetic acid–enhanced MRI. Synovitis, bone edema, and bone erosion (the latter two included as bone lesions at the wrist joints); metacarpophalangeal joints; and proximal interphalangeal joints were considered as MRI‐proven joint injury. Japan College of Rheumatology–certified rheumatologists had given a physical examination just before the MRI study. The presence of tender and/or swollen joints in the same fields as MRI was considered as joint injury on physical examination. The association of MRI‐proven joint injury with physical examination–proven joint injury was examined.

Results

A total of 1,110 sites were available to be examined. MRI‐proven joint injury was found in 521 sites, whereas the other 589 sites were normal. Physical examination–proven joint injury was found in 305 sites, which was significantly low as compared with MRI‐proven joint injury (P = 1.1 × 10^?12 versus MRI). Joint injury on physical examination was not found in 81.5% of the sites where MRI findings were normal. Furthermore, an association of the severity of MRI‐proven joint injury with that of joint injury on physical examination was clearly demonstrated (P = 1.6 × 10^?15, r_s = 0.469).

Conclusion

Our present data suggest that MRI is not only sensitive but accurately reflects the joint injury in patients with early‐stage RA.

     

Brief Report: Inhibition of interleukin‐6 function corrects Th17/Treg cell imbalance in patients with rheumatoid arthritis

Objective

From an immunologic standpoint, the mechanisms by which treatment with tocilizumab (TCZ), a humanized anti–interleukin‐6 (anti–IL‐6) receptor antibody, results in improvement in rheumatoid arthritis (RA) patients are still not fully understood. In vitro studies and studies in mouse models have demonstrated the critical role of IL‐6 in Th17 cell differentiation. Th17 lymphocytes have been shown to be strongly involved in RA pathogenesis, and the purpose of this study was to investigate the effect of IL‐6 blockade on the balance between Th17 cells and Treg cells in patients with active RA.

Methods

Patients with active RA for whom TCZ had been prescribed by a rheumatologist were enrolled in this study. Phenotypic analyses of T cell populations were performed, and the Disease Activity Score in 28 joints (DAS28) was assessed. Serum cytokine levels and other parameters of inflammation were measured before the first infusion and after the third infusion of TCZ (8 mg/kg).

Results

Compared to controls, levels of Th17 cells (CD4+IL‐17+) were increased and Treg cells (CD4+CD25^highFoxP3+) were decreased in the peripheral blood of patients with active RA. The suppressive function of circulating Treg cells was not impaired in patients with active RA. TCZ treatment induced a significant decrease in the DAS28 associated with a significant decrease in the percentage of Th17 cells (from a median of 0.9% to 0.45%; P = 0.009) and an increase in the percentage of Treg cells (from a median of 3.05% to 3.94%; P = 0.0039) in all patients.

Conclusion

This study demonstrates for the first time that inhibition of IL‐6 function by TCZ corrects the imbalance between Th17 cells and Treg cells in patients with RA.

     

Evaluation of classical complement pathway activation in rheumatoid arthritis: Measurement of C1q–C4 complexes as novel activation products

Objective

Novel activation products that are stable and minimally susceptible to in vitro artefacts have recently been described in the classical complement pathway. The present study assessed circulating levels of these products, i.e., covalent complexes between the recognition molecule of the classical pathway (C1q) and activated C4, in plasma samples from patients with rheumatoid arthritis (RA) to establish the relationship between these levels and the clinical and immunologic parameters in these patients.

Methods

C1q–C4 levels were measured in plasma samples from 41 patients with active RA and 43 patients with inactive RA. These levels were related to other complement activation products and to disease activity according to the Disease Activity Score in 28 joints (DAS28), using Spearman's rank correlations.

Results

C1q–C4 plasma levels were significantly higher in patients with active RA as compared with patients with RA in clinical remission (median 3.3 arbitrary units [AU], range 0.4–13.4 versus 1.7 AU, range 0.2–5.5; P = 0.0001), suggesting that activation of the classical complement pathway reflects disease activity. This was supported by a significant correlation between C1q–C4 levels and the DAS28 (r = 0.398, P = 0.0002). Levels of other complement activation products, such as activated C4 (C4b/c), were also significantly elevated in patients with active disease compared with patients with inactive disease (P = 0.03), and were correlated with C1q–C4 levels (r = 0.329, P = 0.002). Levels of C1q–C4 complexes were higher in synovial fluid samples than in plasma samples from the 4 patients tested.

Conclusion

Systemic complement activation via the classical pathway in patients with RA correlates with disease activity. These results indicate that C1q–C4 complexes may be used as a biomarker for RA.

     

Abnormal function of high‐density lipoprotein is associated with poor disease control and an altered protein cargo in rheumatoid arthritis

Objective

To characterize the antiinflammatory function of high‐density lipoprotein (HDL) in patients with rheumatoid arthritis (RA) and to identify specific differences in HDL‐associated proteins and enzymes that distinguish proinflammatory HDL from normal, antiinflammatory HDL.

Methods

We studied 132 RA patients. The antiinflammatory function of HDL was assessed by a cell‐free assay, and proinflammatory HDL was defined by an HDL inflammatory index ≥1. Plasma and HDL‐associated protein levels of apolipoprotein A‐I (Apo A‐I), haptoglobin, hemopexin, hemoglobin, and myeloperoxidase (MPO) were measured by direct and sandwich enzyme‐linked immunosorbent assays, respectively. Lecithin:cholesterol acyltransferase (LCAT) activity was measured by a commercially available assay.

Results

Age, disease activity, the presence of erosive disease, non‐Caucasian race, and smoking were significantly associated with proinflammatory HDL on multivariate analysis. Patients with proinflammatory HDL had higher measures of systemic inflammation, and a significant correlation was observed between RA disease activity (using the Disease Activity Score in 28 joints) and the HDL inflammatory index (r = 0.54, P < 0.0001). Compared with patients with antiinflammatory HDL, patients with proinflammatory HDL had significantly higher levels of haptoglobin, hemoglobin, Apo A‐I, and MPO associated with HDL (P < 0.05 for all comparisons except MPO, which was P = 0.05). LCAT activity was lowest in patients with proinflammatory HDL, but was also significantly reduced in RA patients with antiinflammatory HDL as compared with healthy controls (P = 0.001).

Conclusion

Proinflammatory HDL in this RA patient cohort was associated with active disease and an altered protein cargo as compared with antiinflammatory HDL in RA patients and in healthy controls. The antiinflammatory function of HDL was inversely correlated with systemic inflammation in RA patients and may warrant further investigation as a mechanism by which active RA increases cardiovascular morbidity and mortality.

     

Increased intraarticular interleukin‐7 in rheumatoid arthritis patients stimulates cell contact–dependent activation of CD4+ T cells and macrophages

Objective

To determine the level of intraarticular expression of interleukin‐7 (IL‐7) in patients with rheumatoid arthritis (RA) and to investigate the mechanisms by which IL‐7 facilitates activation of CD4+ T cells and monocyte/macrophages in RA.

Methods

IL‐7 levels were measured in synovial fluid obtained from patients with RA and patients with osteoarthritis (OA). Immunohistologic analysis was used to assess the expression of IL‐7 in synovial tissue from patients with RA. Proliferation and activation markers were determined in order to measure the effect of IL‐7 on mononuclear cells, isolated CD4+ T cells, and monocyte/macrophages from the peripheral blood and synovial fluid. Cocultures of CD4+ T cells and monocytic cells in the absence or presence of a semipermeable membrane were performed to assess the extent to which IL‐7 induces its effects, either contact dependently or via soluble mediators.

Results

IL‐7 levels were increased in synovial fluid from patients with RA compared with the levels in synovial fluid from patients with OA. Macrophages, fibroblasts, and endothelial cells in the joint lining tissue expressed abundant IL‐7. In vitro, synovial fluid CD4+ T cells and macrophages were hyperresponsive to IL‐7 when compared with peripheral blood cells. Furthermore, IL‐7 enhanced cell contact–dependent activation of CD4+ T cells and monocyte/macrophages.

Conclusion

The abundant intraarticular expression of IL‐7 and the stimulation by IL‐7 of contact‐dependent activation of CD4+ T cells and monocytic cells indicate that this cytokine plays an important proinflammatory role in RA synovitis. Further identification of IL‐7–induced pathways may improve understanding of the important interactive role of CD4+ T cells and monocytic cells in RA.

     

Periarticular bone structure in rheumatoid arthritis patients and healthy individuals assessed by high‐resolution computed tomography

Objective

To define the nature of structural bone changes in patients with rheumatoid arthritis (RA) compared with those in healthy individuals by using the novel technique of high‐resolution microfocal computed tomography (micro‐CT).

Methods

Fifty‐eight RA patients and 30 healthy individuals underwent a micro‐CT scan of the proximal wrist and metacarpophalangeal joints. Bone lesions such as cortical breaks, osteophytes, and surface changes were quantified on 2‐dimensional (2‐D) slices as well as by using 3‐D reconstruction images, and exact localization of lesions was recorded.

Results

Micro‐CT scans could detect bone lesions <0.5 mm in width or depth. Small erosions could be observed in healthy individuals and RA patients, whereas lesions >1.9 mm in diameter were highly specific for RA. Cortical breaks were mostly found along the radial sites of the metacarpal heads. No significant difference in the presence of osteophytes between healthy individuals and RA patients was found. Cortical surface changes, presumably cortical thinning and fenestration, became evident from 3‐D reconstructions and were more pronounced in RA patients.

Conclusion

Micro‐CT allows exact detection of morphologic changes of juxtaarticular bone in healthy individuals and RA patients. Even healthy individuals occasionally show bone changes, but the severity of these lesions, with the exception of osteophytes, is greater in RA patients. Thus, micro‐CT allows accurate differentiation among physiologic bone changes in joints and among types of pathologic bone damage resulting from RA.

     

Expression of hypoxia‐inducible factor 1α by macrophages in the rheumatoid synovium: Implications for targeting of therapeutic genes to the inflamed joint

Objective

To determine if the rheumatoid synovium is a suitable target for hypoxia‐regulated gene therapy.

Methods

Sequential sections of wax‐embedded synovial membrane samples were obtained from 10 patients with rheumatoid arthritis (RA), 10 with primary osteoarthritis (OA), and from 6 healthy controls. Membrane sections from each patient were immunostained for hypoxia‐inducible factor 1α (HIF‐1α) and CD68 (a pan–macrophage marker).

Results

HIF‐1α was expressed abundantly by macrophages in most rheumatoid synovia, predominantly close to the intimal layer but also in the subintimal zone. There was markedly lower expression of HIF‐1α in OA synovia, and it was absent from all of the healthy synovia.

Conclusion

These observations indicate that macrophages transduced with a therapeutic gene under the control of a hypoxia‐inducible promoter could be administered to RA patients systemically. Migration of these cells to synovial tissue would result in the transgene being switched on in diseased joints but not in healthy tissues.