Tenosynovitis and osteoclast formation as the initial preclinical changes in a murine model of inflammatory arthritis

Work-related physical strain and development of joint inflammation in the trajectory of emerging inflammatory and rheumatoid arthritis: a prospective cohort study

OBJECTIVES

Rheumatoid arthritis (RA) mainly affects small joints. Despite the mechanical function of joints, the role of mechanical stress in the development of arthritis is insufficiently understood. We hypothesised that mechanical stress/physical strain is a risk factor for joint inflammation in RA. Therefore, we studied work-related physical strain in subjects with clinically suspected arthralgia (CSA) as a risk factor for the presence of imaging-detected subclinical joint inflammation and the development of clinical arthritis/RA.

METHODS

In 501 CSA patients and 155 symptom-free persons' occupation-related physical strain was quantified using the International Standard Classification of Occupations. Contrast-enhanced hand-MRIs were made and evaluated for joint inflammation (sum of synovitis/tenosynovitis/osteitis). CSA patients were followed on RA development. Age relationship was studied using an interaction term of physical strain with age.

RESULTS

The degree of physical strain in CSA is associated with the severity of joint inflammation, independent of educational-level/BMI/smoking (interaction physical strain-age p=0.007; indicating a stronger association with increasing age). Physical strain is associated with higher tenosynovitis scores, in particular. In symptom-free persons, physical strain was not associated with imaging-detected joint inflammation. Higher degrees of physical strain also associated with higher risks for RA development in an age-dependent manner (HR=1.20 (1.06-1.37)/10-year increase in age), independent of educational-level/BMI/smoking. This association was partly mediated by an effect via subclinical joint inflammation.

CONCLUSIONS

Work-related physical strain increases the risk of subclinical joint inflammation and of developing RA. The age relationship suggests an effect of long-term stress or that tenosynovium is more sensitive to stress at older age. Together, the data indicate that mechanical stress contributes to the development of arthritis in RA.

Tenosynovitis of hand: Causes and complications

Tenosynovitis represents a common clinical condition characterized by inflammation of the synovium that encases the tendon sheath. Although tenosynovities may be noted in any tendon in the body, extremities such as hand, and foot remain the sites of high predilection to acquire this condition. The predominant cause of this predilection rests in the intricate tendon arrangements in these extremities that permit fine motor actions. This editorial explores the common causes and the complications associated with this condition to improve the understanding of the readers of this common condition encountered in our everyday clinical practice.

The Natural Sequence in Which Subclinical Inflamed Joint Tissues Subside or Progress to Rheumatoid Arthritis: A Study of Serial MRIs in the TREAT EARLIER Trial

OBJECTIVE

The natural trajectory of clinical arthritis progression at the tissue level remains elusive. We hypothesized that subclinical inflammation in different joint tissues (synovitis, tenosynovitis, osteitis) increases in a distinct temporal order in patients with clinically suspect arthralgia (CSA) who develop rheumatoid arthritis (RA) and subsides in a different sequence when CSA spontaneously resolves.

METHODS

We studied 185 serial magnetic resonance images (MRIs) from CSA patients with subclinical joint inflammation from the placebo arm of the TREAT EARLIER trial: 52 MRIs from 21 RA progressors (MRIs conducted at 1 year before, at 4 months before, and upon RA development), and 133 MRIs from 35 patients with spontaneous resolution of pain (MRIs conducted at baseline and at 4, 12, and 24 months). MRIs were scored for osteitis, synovitis, and tenosynovitis. We used cross-lagged models to evaluate 2 types of time patterns between pairs of inflamed tissues: a simultaneous pattern (coinciding changes) and a subsequent pattern (inflammatory changes in 1 tissue preceding changes in another tissue).

RESULTS

In patients who developed RA, synovitis, tenosynovitis, and osteitis increased simultaneously. Increasing osteitis occurred in the final 4 months before RA diagnosis, following incremental tenosynovitis and synovitis changes during the 1 year to 4 months before diagnosis (P < 0.01). In anti-citrullinated protein antibody (ACPA)-positive and ACPA-negative patients who progressed to RA, osteitis increased just before RA development. In patients with pain resolution, simultaneous decreases in synovitis, tenosynovitis, and osteitis occurred, with tenosynovitis decreasing in the first 4 months after CSA onset preceding decreasing synovitis and osteitis during 4-12 months (P = 0.02 and P < 0.01).

CONCLUSION

We identified natural sequences of subclinical inflammation in different joint tissues, which deepens our understanding of clinical arthritis and RA development. During RA progression, increasing osteitis followed previous increases in tenosynovitis and synovitis. During pain resolution, tenosynovitis decreased first, followed by decreasing synovitis and osteitis.

Importance of tenosynovitis in preventing the progression through rheumatoid arthritis continuum

Rheumatoid arthritis (RA) has long been characterized by synovitis and bone erosions typically developing symmetrically in small joints. However, recent advances in imaging modalities have indicated frequent association of tenosynovitis with RA, and some consider tenosynovitis to be not just a complication but a major trait of RA. Furthermore, as there are cases with tenosynovitis preceding the clinical detection of inflammatory arthritis in predisposed individuals, tenosynovitis may constitute an important biomarker in defining the pre-RA phase of disease development. Tenosynovitis itself must be treated as it causes functional impairment and physical as well as socioeconomic burden, and its treatment may result in effective prevention of RA development at a pre-arthritic stage. Thus, further efforts need to be taken in detecting and treating tenosynovitis in the pre-RA stage, which can be facilitated by ultrasonography and magnetic resonance imaging.

The Role of Viral Infections in the Onset of Autoimmune Diseases

Autoimmune diseases (AIDs) are the consequence of a breach in immune tolerance, leading to the inability to sufficiently differentiate between self and non-self. Immune reactions that are targeted towards self-antigens can ultimately lead to the destruction of the host's cells and the development of autoimmune diseases. Although autoimmune disorders are comparatively rare, the worldwide incidence and prevalence is increasing, and they have major adverse implications for mortality and morbidity. Genetic and environmental factors are thought to be the major factors contributing to the development of autoimmunity. Viral infections are one of the environmental triggers that can lead to autoimmunity. Current research suggests that several mechanisms, such as molecular mimicry, epitope spreading, and bystander activation, can cause viral-induced autoimmunity. Here we describe the latest insights into the pathomechanisms of viral-induced autoimmune diseases and discuss recent findings on COVID-19 infections and the development of AIDs.

Eccentric Versus Concentric Exercises in Patients With Rheumatoid Arthritis and Rotator Cuff Tendinopathy: A Randomized Comparative Study

OBJECTIVE

To determine the efficacy of concentric vs. eccentric exercise in improving shoulder function, pain, and tendon characteristics for patients with rheumatoid arthritis and rotator cuff tendinopathy.

METHODS

Forty patients with rheumatoid arthritis and rotator cuff tendinopathy were divided into either concentric or eccentric exercise groups, with 20 patients in each group. Patients received 12 sessions at a pace of 3 sessions per week. Shoulder Pain and Disability Index (SPADI), the visual analogue scale (VAS), supraspinatus and subscapularis thickness, echo pixels, and the Disease Activity Score-28-erythrocyte sedimentation rate (DAS-28-ESR) were assessed at baseline and post-treatment.

RESULTS

There was a significant difference between the concentric and eccentric groups regarding SPADI and VAS scores in favor of the eccentric group. However, there was no significant difference between the two groups regarding tendon thickness, echo pixels, or DAS-28-ESR.

CONCLUSION

Eccentric exercises were more effective than concentric exercises in improving shoulder function and pain intensity. However, neither of the two types of exercises was superior in improving tendon characteristics or disease activity.

Calcium-Permeable Channels Cooperation for Rheumatoid Arthritis: Therapeutic Opportunities

Rheumatoid arthritis is a common autoimmune disease that results from the deposition of antibodies–autoantigens in the joints, leading to long-lasting inflammation. The main features of RA include cartilage damage, synovial invasion and flare-ups of intra-articular inflammation, and these pathological processes significantly reduce patients’ quality of life. To date, there is still no drug target that can act in rheumatoid arthritis. Therefore, the search for novel drug targets has become urgent. Due to their unique physicochemical properties, calcium ions play an important role in all cellular activities and the body has evolved a rigorous calcium signaling system. Calcium-permeable channels, as the main operators of calcium signaling, are widely distributed in cell membranes, endoplasmic reticulum membranes and mitochondrial membranes, and mediate the efflux and entry of Ca2+. Over the last century, more and more calcium-permeable channels have been identified in human cells, and the role of this large family of calcium-permeable channels in rheumatoid arthritis has gradually become clear. In this review, we briefly introduce the major calcium-permeable channels involved in the pathogenesis of RA (e.g., acid-sensitive ion channel (ASIC), transient receptor potential (TRP) channel and P2X receptor) and explain the specific roles and mechanisms of these calcium-permeable channels in the pathogenesis of RA, providing more comprehensive ideas and targets for the treatment of RA.

Analysis of combined deficiency of interleukin-1 and -6 versus single deficiencies in TNF-mediated arthritis and systemic bone loss

Aims

Insufficient treatment response in rheumatoid arthritis (RA) patients requires novel treatment strategies to halt disease progression. The potential benefit of combination of cytokine-inhibitors in RA is still unclear and needs further investigation. To explore the impact of combined deficiency of two major cytokines, namely interleukin (IL)-1 and IL-6, in this study double deficient mice for IL-1αβ and IL-6 were investigated in different tumour necrosis factor (TNF)-driven inflammatory bone disorders, namely peripheral arthritis and sacroiliitis, as well as systemic bone loss.

Methods

Disease course, histopathological features of arthritis, and micro-CT (µCT) bone analysis of local and systemic bone loss were assessed in 15-week-old IL1^-/-IL6^-/-hTNFtg in comparison to IL1^-/-hTNFtg, IL6^-/-hTNFtg, and hTNFtg mice. µCT bone analysis of single deficient and wild-type mice was also performed.

Results

Combined deficiency of IL-1/IL-6 markedly ameliorated TNF-mediated arthritis and bilateral sacroiliitis, but without additive benefits compared to single IL-1 deficiency. This finding confirms the important role of IL-1 and the marginal role of IL-6 in TNF-driven pathways of local joint damage, but questions the efficacy of potential combinatorial therapies of IL-1 and IL-6 in treatment of RA. In contrast, combined deficiency of IL-1/IL-6 led to an additive protective effect on TNF-driven systemic bone loss compared to single IL-1 and IL-6 deficiency. This finding clearly indicates a common contribution of both IL-1 and IL-6 in TNF-driven systemic bone loss, and points to a discrepancy of cytokine dependency in local and systemic TNF-driven mechanisms of inflammatory arthritis.

Conclusion

Combinatorial treatments in RA might provide different benefits to inflammatory local arthritis and systemic comorbidities.

Cite this article: Bone Joint Res 2022;11(7):484–493.

During development of rheumatoid arthritis, intermetatarsal bursitis may occur before clinical joint swelling: a large imaging study in patients with clinically suspect arthralgia

Objectives

Intermetatarsal bursitis (IMB) represents juxta-articular synovial inflammation of the intermetatarsal bursae. Recent MRI studies identified IMB as feature of early RA, but whether IMB already occurs in the pre-arthritic phase is unknown. We performed a large MRI study in clinically suspect arthralgia (CSA) to assess the occurrence and prognostic value of IMB.

Methods

A total of 577 consecutive CSA patients underwent contrast-enhanced MRI of the forefoot, metacarpophalangeal joints and wrist. MRIs were evaluated for subclinical synovitis/tenosynovitis/osteitis in line with the RA MRI scoring system (summed as RAMRIS inflammation) and for IMB. IMB was considered present if uncommon in the general population at the same location (i.e. size scored above the 95th percentile in age-matched symptom-free controls). The relation of IMB with other MRI-detected subclinical inflammation (synovitis/tenosynovitis/osteitis) was studied. Cox-regression assessed the association with clinical arthritis development during median 25 months follow-up. ACPA stratification was performed.

Results

At presentation with CSA, 23% had IMB. IMB was more frequent in ACPA-positive than ACPA-negative CSA (47% vs 19%, P < 0.001). Patients with IMB were more likely to also have subclinical synovitis [OR 3.4 (95% CI 1.8, 6.5)] and tenosynovitis [5.9(2.8, 12.6)]. IMB conferred higher risk of developing arthritis [HR 1.6(1.0–2.7) adjusted for other subclinical inflammation]. IMB-presence predicted arthritis development in ACPA-positive CSA [adjusted HR 2.2(1.0–4.7)], but not in ACPA-negative CSA-patients [0.8(0.4–1.7)].

Conclusion

Approximately a quarter of CSA patients have IMB, which is frequently accompanied by subclinical synovitis and tenosynovitis. IMB precedes development of clinical arthritis, particularly in ACPA-positive CSA. These results reinforce the notion that juxta-articular synovial inflammation is involved in the earliest phases of RA development.

Differing time-orders of inflammation decrease between ACPA subsets in RA patients suggest differences in underlying inflammatory pathways

OBJECTIVES

Advanced imaging modalities have shown that not only joints but also bones and tendon sheaths can be inflamed at diagnosis of RA. We aimed to better understand the time-order in which the inflamed tissues respond to DMARD treatment. Also, because ACPA status may reflect a different pathophysiology, differences in time-order of inflammation decrease were hypothesized between these disease types.

METHODS

A total of 216 consecutive patients presenting with RA (n = 176) or undifferentiated arthritis (n = 40), who all started with conventional synthetic DMARD treatment, were studied. 1.5T contrast-enhanced hand and foot MRIs were performed before treatment and after 4, 12 and 24 months. Cross-lagged models evaluated the influence of two time patterns: a simultaneous pattern ('change in one inflammatory feature associated with change in another feature') and a subsequent pattern ('change in one inflammatory feature preceded change in another feature'). ACPA stratification was performed.

RESULTS

The median symptom duration at presentation was 13 weeks. Forty-four percent of patients was ACPA-positive. All pairs of inflammatory features decreased simultaneously in all time intervals (0-4/4-12/12-24 months; P < 0.05). Moreover, time-orders were identified: synovitis decrease preceded tenosynovitis decrease (0-4 to >4-12 months; P = 0.02 and 4-12 to >12-24 months; P = 0.03). Largely similar results were obtained in both ACPA subgroups. Additionally, in ACPA-positive but not ACPA-negative patients, synovitis decrease preceded osteitis decrease (4-12 to >12-24 moths; P = 0.002).

CONCLUSION

This study increased the understanding of the response to treatment on the tissue level. In addition to simultaneous decrease of inflammation, synovitis decrease preceded tenosynovitis decrease. Differences in time-order of inflammation decrease between ACPA subgroups suggest differences in underlying inflammatory pathways.

Psoriatic Dactylitis: Current Perspectives and New Insights in Ultrasonography and Magnetic Resonance Imaging

Dactylitis, one of the most typical features of psoriatic arthritis (PsA), is the diffuse swelling of the digits and is determined by the involvement of different anatomic structures, including: the subcutaneous fibrous tissue “accessory pulley” system; flexor tendons, with their related structures; the articular synovium; the small enthesis of the hands. Dactylitis is currently considered both a marker of disease activity and severe prognosis and its importance in PsA is emphasized by the inclusion in the classification criteria of PsA. This review focuses on the role of imaging in the management of PsA patients with dactylitis in clinical practice and in a research setting. Furthermore, imaging could be a valuable tool to assist in unravelling some of the underlying mechanisms of the onset and chronicization of dactylitis in PsA patients.

'SMASH' recommendations for standardised microscopic arthritis scoring of histological sections from inflammatory arthritis animal models

Animal models for inflammatory arthritides such as rheumatoid arthritis (RA) and psoriatic arthritis are widely accepted and frequently used to identify pathological mechanisms and validate novel therapeutic strategies. Unfortunately, many publications reporting on these animal studies lack detailed description and appropriate assessment of the distinct histopathological features of arthritis: joint inflammation, cartilage damage and bone erosion. Therefore, the European consortium BeTheCure, consisting of 38 academic and industrial partners from 15 countries, set as goal to standardise the histological evaluation of joint sections from animal models of inflammatory arthritis. The consensual approach of a task force including 16 academic and industrial scientists as well as laboratory technicians has resulted in the development of the Standardised Microscopic Arthritis Scoring of Histological sections (‘SMASH’) recommendations for a standardised processing and microscopic scoring of the characteristic histopathological features of arthritis, exemplified by four different rodent models for arthritis: murine collagen-induced arthritis, collagen–antibody-induced arthritis, human tumour necrosis factor transgenic Tg197 mice and rat pristane-induced arthritis, applicable to any other inflammatory arthritis model. Through standardisation, the SMASH recommendations are designed to improve and maximise the information derived from in vivo arthritis experiments and to promote reproducibility and transparent reporting on such studies. In this manuscript, we will discuss and provide recommendations for analysis of histological joint sections: identification of the regions of interest, sample preparation, staining procedures and quantitative scoring methods. In conclusion, awareness of the different features of the arthritis pathology in animal models of inflammatory arthritis is of utmost importance for reliable research outcome, and the standardised histological processing and scoring methods in these SMASH recommendations will help increase uniformity and reproducibility in preclinical research on inflammatory arthritis.

Do magnetic resonance imaging-detected erosions predict progression to rheumatoid arthritis in patients presenting with clinically suspect arthralgia? A longitudinal study

Objective: Radiographic joint erosions are a hallmark of rheumatoid arthritis (RA). Magnetic resonance imaging (MRI) is more sensitive than radiographs in detecting erosions. It is unknown whether MRI-detected erosions are predictive for RA development in patients with clinically suspect arthralgia (CSA). Therefore, we investigated the prognostic value of MRI-detected erosions, defined as any MRI erosion, or MRI erosion characteristics that were recently identified as specific for RA in patients with evident arthritis. Method: Patients presenting with CSA (n = 490) underwent contrast-enhanced 1.5 T MRI of the wrist, metacarpophalangeal (MCP) and metatarsophalangeal (MTP) joints. MRIs were scored according to the Rheumatoid Arthritis Magnetic Resonance Imaging Scoring system (RAMRIS). Presence of any MRI erosion (present in < 5% of symptom-free controls) and RA-specific erosion characteristics as identified previously (grade ≥ 2 erosions, erosions in MTP5, erosions in MTP1 if aged < 40 years) were studied with clinically apparent inflammatory arthritis development as outcome. Analyses were corrected for age and MRI-detected subclinical inflammation. Results: Erosions were present in 20%. Presence of any MRI erosion was not associated with arthritis development [multivariable analysis hazard ratio (HR) 0.97 (95% confidence interval 0.59-1.59)]. The different RA-specific erosion characteristics were not predictive [grade ≥ 2 HR 1.05 (0.33-3.34), erosions in MTP5 HR 1.08 (0.47-2.48), and MTP1 if aged < 40 years HR 1.11 (0.26-4.70)]. Erosion scores were higher in anti-citrullinated protein antibody (ACPA)-positive than in ACPA-negative patients (median 2.0 vs 1.0, p = 0.002), and related to more subclinical inflammation. Within both subgroups, MRI erosions were not predictive. Conclusions: MRI-detected erosions in hands and feet were not predictive for inflammatory arthritis development. Therefore, evaluating MRI for erosions in addition to subclinical inflammation does not provide added clinical value in CSA.

Insights into the treatment of rheumatoid arthritis: A paradigm in medicine

Insights into rheumatoid arthritis (RA) have slowly evolved over the last century, but with breathtaking speed over the last 2 decades. While only aspirin and parenteral gold were available in early 20th century, the efficacy of sulfasalazine, glucocorticoids and methotrexate was established around its middle. Identification of pathogenetic pathways was slow, and until today the role of T-cells is enigmatic, while it is clear that genetics via the shared epitope and other genes as well as environmental factors including the metagenome play major roles. More clarity evolved on importance of proinflammatory cytokines, especially TNF and IL-6. The activation of osteoclasts, the culprits of bony joint damage, is amplified by the proinflammatory cytokines. The realization of TNF's central role led to the successful introduction of TNF-inhibitors and subsequently also inhibitors of other cytokines and cells as well as signal transduction. In parallel, the evolution of outcomes research has contributed importantly to RA management. At the turn to the 21st century, improvement criteria and continuous indices were created, allowing reliable therapeutic response determination, including definition of endpoints like remission. Also our understanding of the role of disease activity relative to disease pathology has increased, ultimately fostering the treat-to-target concept and recommendations and, thus, optimal outcomes for RA patients as never been seen before. Similar developments are now ultimately being introduced in the field of psoriatic arthritis. Here many of these aspects are reviewed from a very personal perspective of the author in the hopes of further helping parients with chronic forms of arthritis.

The etiology of rheumatoid arthritis

Rheumatoid arthritis is a heterogeneous disease, which can be, based on data combining genetic risk factors and autoantibodies, sub-classified into ACPA-positive and -negative RA. Presence of ACPA and RF as well as rising CRP-levels in some patients years before onset of clinical symptoms indicate that relevant immune responses for RA development are initiated very early. ACPA are highly specific for RA, whereas RF can also be found among healthy (elderly) individuals and patients with other autoimmune diseases or infection. The most important genetic risk factor for RA development, the shared epitope alleles, resides in the MHC class II region. Shared epitope alleles, however, only predispose to the development of ACPA-positive RA. Smoking is thus far the most important environmental risk factor associated with the development of RA. Studies on synovitis have shown the importance not only of adaptive but also of innate immune responses. In summary of the various results from immunological changes in blood and synovial tissue, the extension of the immune response from a diffuse myeloid to a lympho-myeloid inflammation appears to be associated with a more successful therapeutic response to biologics. With respect to advances in synovitis research, new targets for treatment against pathological subsets of immune cells or fibroblasts are already on the horizon. However, alternative strategies involving the microbiome may play an important role as well and research in this field is growing rapidly.

Multimodal [18 F]FDG PET/CT Is a Direct Readout for Inflammatory Bone Repair: A Longitudinal Study in TNFα Transgenic Mice

In rheumatoid arthritis (RA), chronic joint inflammation leading to bone and cartilage damage is the major cause of functional impairment. Whereas reduction of synovitis and blockade of joint damage can be successfully achieved by disease modifying antirheumatic therapies, bone repair upon therapeutic interventions has only been rarely reported. The aim of this study was to use fluorodeoxyglucose ([¹⁸ F]FDG) and [¹⁸ F]fluoride µPET/CT imaging to monitor systemic inflammatory and destructive bone remodeling processes as well as potential bone repair in an established mouse model of chronic inflammatory, erosive polyarthritis. Therefore, human tumor necrosis factor transgenic (hTNFtg) mice were treated with infliximab, an anti-TNF antibody, for 4 weeks. Before and after treatment period, mice received either [¹⁸ F]FDG, for detecting inflammatory processes, or [¹⁸ F]fluoride, for monitoring bone remodeling processes, for PET scans followed by CT scans. Standardized uptake values (SUV_mean ) were analyzed in various joints and histopathological signs of arthritis, joint damage, and repair were assessed. Longitudinal PET/CT scans revealed a significant decrease in [¹⁸ F]FDG SUVs in affected joints demonstrating complete remission of inflammatory processes due to TNF blockade. In contrast, [¹⁸ F]fluoride SUVs could not discriminate between different severities of bone damage in hTNFtg mice. Repeated in vivo CT images proved a structural reversal of preexisting bone erosions after anti-TNF therapy. Accordingly, histological analysis showed complete resolution of synovial inflammation and healing of bone at sites of former bone erosion. We conclude that in vivo multimodal [¹⁸ F]FDG µPET/CT imaging allows to quantify and monitor inflammation-mediated bone damage and reveals not only reversal of synovitis but also bone repair upon TNF blockade in experimental arthritis. © 2019 The Authors. Journal of Bone and Mineral Research Published by Wiley Periodicals, Inc.

Magnetic resonance imaging-assessed synovial and bone changes in hand and wrist joints of rheumatoid arthritis patients

BACKGROUND/AIMS

Magnetic resonance imaging (MRI) is a sensitive and useful method for the detection of synovitis and joint destruction in rheumatoid arthritis (RA) patients. However, the patterns of MRI-detected bone erosion, bone marrow edema (BME), synovitis, and tenosynovitis have received insufficient attention. Therefore, this study evaluated the patterns of bone erosion, BME, synovitis, and tenosynovitis, and calculated the RA-MRI score (RAMRIS) of patients with RA at the carpal and metacarpophalangeal (MCP) joints using MRI.

METHODS

MRI datasets from 43 RA patients were analyzed. All patients had undergone MRI of one wrist. In addition, 36 patients had MCP joint images taken, and three had also received MRI of the contralateral wrist and MCP joints. The MR images were evaluated for bone erosion, BME, and synovitis in consensus by two blinded readers according to the Outcome Measures in Rheumatology Clinical Trials (OMERACT) RAMRIS. The MRI-detected tenosynovitis was evaluated based on Haavardsholm's tenosynovitis score.

RESULTS

The capitate, lunate, triquetrum, and hamate bones were the most common sites of erosion and BME and showed the highest RAMRIS erosion and BME scores. Moreover, MRI-detected tenosynovitis was present in 78.3% of all patients with RA, and the extensor compartment 4 and flexor digitorum profundus and superficialis were frequently affected.

CONCLUSION

This study identified the distribution and prevalence of MRI-detected bone erosion, BME, synovitis, and tenosynovitis of the wrist and MCP joints in RA patients. The patterns of the MRI-detected abnormalities may help to select sites for the application of MRI protocols in clinical trials and practice.

Patients with Rheumatoid Arthritis Were Associated with a Risk of Rotator Cuff Diseases

Rheumatoid arthritis (RA) commonly causes inflammation in the joints and periarticular structures. The association between RA and rotator cuff (RC) has been reported; however, epidemiological studies on RA and RC tendons are scant. Therefore, we investigated RC disease (RCD) risk and analyzed the effects of RA medication, steroids, and methotrexate, on the risk of RCD for patients with RA. We conducted a retrospective cohort study with a 6-year longitudinal follow-up in Taiwan. Patients who received RA diagnoses between 2004 and 2008 were enrolled in the study cohort. The non-RA control cohort comprised age- and sex-matched controls. Propensity score matching was used for other comorbidities and treatments. The hazard ratios (HRs) and adjusted HRs (aHRs) were estimated after confounders were adjusted for. Effects of steroid and methotrexate use on RCD risk were also analyzed. We enrolled 4521 RA patients (study cohort) and 22,605 matched controls. RCD incidence was 145 and 91 per 100,000 person-years in the RA and control cohorts, respectively. In the RA cohort, the crude HR for RCD was 1.62 (95% confidence interval (CI), 1.41–1.86, p < 0.001), and the aHR was 1.56 (95% CI, 1.36–1.79, p < 0.001). The methotrexate nonusers exhibited an aHR (vs. controls) of 1.61 (95% CI, 1.40–1.85, p < 0.001), but the methotrexate users did not have a significantly higher aHR than the controls. The steroid nonusers had an aHR (vs. controls) of 1.69 (95% CI, 1.46–1.96, p < 0.001), but the aHR of the steroid users was not significantly higher than the control aHR. Patients with RA had a higher risk for RCD compared with the non-RA control cohort. Steroids or methotrexate use significantly reduces the risk of RCD occurrence in patients with RA. Treatment for RCD symptoms and controlling inflammatory process are important to ensure high-quality care for patients with RA.

Transgenic mice overexpressing human TNF-α experience early onset spontaneous intervertebral disc herniation in the absence of overt degeneration

There is a well-established link between cytokine expression and the progression of intervertebral disc degeneration. Among these cytokines, interleukin-1β (IL-1β) and tumor necrosis factor-α (TNF-α) are the most commonly studied. To investigate whether systemic hTNF-α overexpression affects intervertebral disc health, we studied the spine phenotype of Tg197 mice, a widely used hTNF-α transgenic line. These mice were studied at 12–16 weeks of age using comprehensive histochemical and immunohistological analysis of the spinal motion segment. Micro-CT analysis was performed to quantify vertebral trabecular bone architecture. The Tg197 mice evidenced spontaneous annular tears and herniation with increased vascularity in subchondral bone and significant immune cell infiltration. The full-thickness annular tear without nucleus pulposus (NP) extrusion resulted in neutrophil, macrophage, and mast cell infiltration into the disc, whereas the disc with full-thickness tear and pronounced NP herniation showed additional presence of CD4+ and CD8+ T cells. While the observed defects involved failure of the annular, endplate, and vertebral junction, there were no obvious alterations in the collagen or aggrecan content in the NP and annulus fibrosus or the maturity of collagen fibers in Tg197 mice. Despite elevated systemic inflammation and pronounced loss of trabecular bone in the vertebrae, intact Tg197 discs were healthy and showed an increase in NP cell number. The NP cells in intact discs preserved expression of phenotypic markers: CAIII, Glut1, and Krt19. In conclusion, elevated systemic TNF-α increases the susceptibility of mice to spontaneous disc herniation and possibly radiculopathy, without adversely affecting intact intervertebral disc health.

Sequence of joint tissue inflammation during rheumatoid arthritis development

Objective

Subclinical joint inflammation in patients with arthralgia is predictive for progression to rheumatoid arthritis (RA). However, the time course of progression for bone marrow edema (osteitis), synovitis, and/or tenosynovitis is unsettled. This longitudinal study assessed the course of magnetic resonance imaging (MRI)-detected subclinical joint inflammation during progression to RA.

Methods

Patients that progressed from clinically suspect arthralgia (CSA) to RA underwent 1.5-T MRI of the metacarpophalangeal (MCP), wrist, and metatarsophalangeal (MTP) joints at presentation with arthralgia and at first identification of synovitis assessed through physical examination (n = 31). MRIs were evaluated for osteitis, synovitis, tenosynovitis, and erosions by two readers, blinded for clinical data and order in time. To estimate changes in MRI scores between the asymptomatic state and CSA onset, scores of MRI features at CSA baseline were compared with scores from age-matched symptom-free persons.

Results

At presentation with CSA, synovitis and tenosynovitis scores were higher than scores from age-matched symptom-free persons (p = 0.004 and p = 0.001, respectively). Anti-citrullinated protein antibody (ACPA)-positive arthralgia patients also had increased osteitis scores (p = 0.04). Median duration between presentation with arthralgia and RA development was 17 weeks. During progression to RA, synovitis and osteitis increased significantly (p = 0.001 and p = 0.036, respectively) in contrast to tenosynovitis and erosion scores. This pattern was similar in both ACPA subsets, although statistical significance was reached for synovitis and osteitis in ACPA-negative but not ACPA-positive RA.

Conclusion

Increased tenosynovitis and synovitis scores at CSA onset and the increase in synovitis and osteitis during progression to RA suggest an ‘outside-in’ temporal relationship of arthritis development, in particular for ACPA-negative RA. For ACPA-positive RA, further studies are needed.

Electronic supplementary material

The online version of this article (10.1186/s13075-018-1756-z) contains supplementary material, which is available to authorized users.

Development of clinically apparent synovitis: a longitudinal study at the joint level during progression to inflammatory arthritis

Introduction

Subclinical inflammation, detected by MRI, in patients with arthralgia is predictive for development of inflammatory arthritis (IA). However, within patients that develop IA, the course of inflammation at the joint level during this transition is unknown. This longitudinal study assessed progression of inflammation at the joint level.

Methods

350 joints (unilateral metacarpophalangeals (MCPs), wrist, metatarsophalangeal (MTP) joints) of 35 patients presenting with clinically suspect arthralgia (CSA) that progressed to IA were studied at presentation with CSA and subsequently when clinical synovitis was first identified at joint examination (median time interval 17 weeks). At both time points, subclinical inflammation (bone marrow oedema, synovitis, tenosynovitis) was evaluated with MRI and joint examination was performed.

Results

At presentation with CSA, 71 joints showed subclinical inflammation. During progression to IA, 20% of these joints had resolution of inflammation, 60% had persistent inflammation and 20% progressed to clinical synovitis. Of all joints that had developed clinical synovitis (n = 45), no prior subclinical inflammation was detected in 69%. Similar results were observed for anticitrullinated protein antibodies (ACPA)-positive and ACPA-negative patients.

Conclusions

This longitudinal study demonstrated moderate correlations between joints with subclinical inflammation and joints that developed clinical synovitis. These data imply that IA development is a more systemic rather than a locally outgrowing process.

The role of imaging in early diagnosis and prevention of joint damage in inflammatory arthritis

INTRODUCTION

Inflammatory arthritis is characterized by chronic inflammation in the synovium, associated with degradation of cartilage and erosion of juxta-articular bone. The bone loss and joint destruction mediated by aberrant immunological responses resulting in proinflammatory cytokine release and various immune cell activation are known as osteoimmunology. Areas covered: A structured literature search including Medline and PubMed, Cochrane meta-analyses and abstracts of international congresses was performed to review joint damage in inflammatory arthritis in terms of pathogenesis, novel imaging assessment, and prevention. Expert commentary: Deeper understanding of the integration of the skeletal and immune as well as inflammatory system is paving the way to prevent bone loss and bone destruction in inflammatory arthritis. With the availability of various imaging modalities such as ultrasound, magnetic resonance imaging (MRI) and high-resolution peripheral quantitative computed tomography (HR-pQCT), we are now able to detect early joint damage, early diagnosis of inflammatory arthritis, monitor the progression or even ascertain whether the inflammatory process is effectively suppressed to allow repair of joint damage by novel therapeutic agents.

Fabrication of a triptolide-loaded and poly-γ-glutamic acid-based amphiphilic nanoparticle for the treatment of rheumatoid arthritis

Triptolide (TP) exhibits immunosuppressive, cartilage-protective and anti-inflammatory effects in rheumatoid arthritis. However, the toxicity of TP limits its widespread use. To decrease the toxic effects, we developed a novel nano-drug carrier system containing TP using poly-γ-glutamic acid-grafted di-tert-butyl L-aspartate hydrochloride (PAT). PAT had an average diameter of 79±18 nm, a narrow polydispersity index (0.18), a strong zeta potential (−32 mV) and a high drug encapsulation efficiency (EE₁=48.6%) and loading capacity (EE₂=19.2%), and exhibited controlled release (t_1/2=29 h). The MTT assay and flow cytometry results indicated that PAT could decrease toxicity and apoptosis induced by free TP on RAW264.7 cells. PAT decreased lipopolysaccharides/interferon γ-induced cytokines expression of macrophage (P<0.05). In vivo, PAT accumulated at inflammatory joints, improved the survival rate and had fewer side effects on tumor necrosis factor α transgenic mice, compared to TP. The blood biochemical indexes revealed that PAT did not cause much damage to the kidney (urea nitrogen and creatinine) and liver (alanine aminotransferase and aspartate aminotransferase). In addition, PAT reduced inflammatory synovial tissue area (P<0.05), cartilage loss (P<0.05), tartrate-resistant acid phosphatase-positive osteoclast area (P<0.05) and bone erosion (P<0.05) in both knee and ankle joints, and showed similar beneficial effect as free TP. In summary, our newly formed nanoparticle, PAT, can reduce the toxicity and guarantee the efficacy of TP, which represents an effective drug candidate for RA with low adverse side effect.

Rheumatoid arthritis

Rheumatoid arthritis (RA) is a chronic, inflammatory, autoimmune disease that primarily affects the joints and is associated with autoantibodies that target various molecules including modified self-epitopes. The identification of novel autoantibodies has improved diagnostic accuracy, and newly developed classification criteria facilitate the recognition and study of the disease early in its course. New clinical assessment tools are able to better characterize disease activity states, which are correlated with progression of damage and disability, and permit improved follow-up. In addition, better understanding of the pathogenesis of RA through recognition of key cells and cytokines has led to the development of targeted disease-modifying antirheumatic drugs. Altogether, the improved understanding of the pathogenetic processes involved, rational use of established drugs and development of new drugs and reliable assessment tools have drastically altered the lives of individuals with RA over the past 2 decades. Current strategies strive for early referral, early diagnosis and early start of effective therapy aimed at remission or, at the least, low disease activity, with rapid adaptation of treatment if this target is not reached. This treat-to-target approach prevents progression of joint damage and optimizes physical functioning, work and social participation. In this Primer, we discuss the epidemiology, pathophysiology, diagnosis and management of RA.

Evaluation of the diagnostic accuracy of hand and foot MRI for early Rheumatoid Arthritis

Objectives

To assess the diagnostic value of MRI for early RA. In some RA patients, a classifiable diagnosis cannot be made at first presentation; these patients present with unclassified arthritis (UA). The use of MRI for early diagnosis of RA is recommended, yet the evidence for its reliability is limited.

Methods

MRI of hand and foot was performed in 589 early arthritis patients included in the Leiden Early Arthritis Clinic (229 presented with RA, 159 with other arthritides and 201 with UA). Symptom-free controls provided a reference for defining an abnormal MRI. In preliminary investigations, MRI of patients who presented with RA was compared with MRI of symptom-free controls and of patients with other arthritides. Thereafter, the value of MRI in early RA diagnosis was determined in UA patients using the 1-year follow-up on fulfilling the 1987 RA criteria and start of disease-modifying drugs as outcomes.

Results

Preliminary investigations were promising. Of the UA patients, 14% developed RA and 37% started disease-modifying treatment. MRI-detected tenosynovitis was associated with RA development independent of other types of MRI-detected inflammation [odds ratio (OR) = 7.5, 95% CI: 2.4, 23] and also independent of age and other inflammatory measures (swollen joints, CRP) (OR = 4.2, 95% CI: 1.4, 12.9). Within UA patients, the negative predictive value of abnormal tenosynovitis was 95% (95% CI: 89%, 98%) and the positive predictive value 25% (95% CI: 17%, 35%). The performance was best in the subgroup of UA patients presenting with oligoarthritis (18% developed RA): the positive predictive value was 36% (95% CI: 23%, 52%), the negative predictive value was 98% (95% CI: 88%, 100%), the sensitivity was 93% (95% CI: 70%, 99%) and the specificity was 63% (95% CI: 51%, 74%).

Conclusion

MRI contributes to the identification of UA patients who will develop RA, mostly in UA patients presenting with oligoarthritis.

Tumor Necrosis Factor Alpha Overexpression Induces Mainly Osteoclastogenesis at the Vertebral Site

Syndesmophyte occurrence and axial bone loss were investigated in the heterozygous Tg187 tumor necrosis factor (TNF) transgenic mouse model (Tg-huTNF) of arthritis. Female and male Tg-huTNF mice were compared to wild-type mice (WT) at 2, 4, 6, 8, and 10 weeks. Syndesmophytes, intervertebral disc space, osteoclasts, osteoid surface, and vertebra microarchitecture were assessed by histomorphometry and microcomputed tomography. No spontaneous syndesmophyte formation was detected in Tg-huTNF compared to WT mice. However, increased porosity was observed mainly in peridiscal lumbar vertebra. Accordingly, bone microarchitecture parameters were altered in Tg-huTNF mice, with decrease in bone volume fraction, and trabecular number and thickness after 6 weeks compared to WT (p < 0.05). Osteoclast count and surface were increased (p < 0.01). Moreover, the non-mineralized (osteoid) surface was also increased in Tg-huTNF after 6 weeks (p < 0.01). Despite increased osteoclast and osteoid surfaces, an imbalance between both was observed in favour of osteoid surface at the early phase and then to osteoclast surface. These results demonstrated an axial bone loss in the Tg-huTNF model, additional to the common limb arthritis, related to overexpression of TNF. However, the absence of syndesmophyte and the increase of osteoid surface suggested that chronic inflammation might block bone mineralisation. Finally, the relative increased osteoid surface was not enough to compensate the high osteoclast activity.

Sonographic Characteristics of Extensor Tendon Abnormalities and Relationship With Joint Disease Activity in Rheumatoid Arthritis: A Pilot Study

OBJECTIVES

To characterize abnormalities in the dorsal extensor tendons of the hand and determine the importance of these findings in rheumatoid arthritis.

METHODS

A retrospective cross-sectional study was done on 26 patients with rheumatoid arthritis who had sonography of their hands. B-mode and power Doppler joint activity were scored, and the extensor tendons were examined for B-mode changes and power Doppler signals. B-mode changes included anechoic fluid around tendons, hypoechoic tissue around tendons, paratendon tissue and tendon thickening, as well as vascularity around the tendon, for which peritendon power Doppler signals were recorded.

RESULTS

Forty-one hands and 205 joints were reviewed. Anechoic fluid around the tendons and peritendon power Doppler signals were observed in 41% and 39%, respectively; 44% and 28% of patients had B-mode and power Doppler scores in the upper tertile, respectively. For both B-mode and power Doppler scores, 3 categories or tertiles were created, 0 to 0.9, 1 to 1.9, and 2 to 3. We reported the percentage of patients with power Doppler and B-mode scores in this category. The severity of synovitis was associated with anechoic fluid around the tendons and peritendon power Doppler signals according to the Cochran-Mantel-Haenszel test. The common odds ratio was 3.52 (95% confidence interval, 1.45- 8.53) for anechoic fluid around the tendons and severe synovitis. The common odds ratio was 2.52 (95% confidence interval, 1.13-5.63) for peritendon power Doppler signals and severe synovitis.

CONCLUSIONS

Findings at the dorsal extensor tendons were anechoic fluid around tendons, hypoechoic tissue around tendons, peritendon power Doppler signals, and tendon thickening. Patients with anechoic fluid and power Doppler signals were found to have more severe disease activity at the joints based on B-mode and power Doppler scores.

Brief Report: Treatment of Tumor Necrosis Factor-Transgenic Mice With Anti-Tumor Necrosis Factor Restores Lymphatic Contractions, Repairs Lymphatic Vessels, and May Increase Monocyte/Macrophage Egress

OBJECTIVE

Recent studies have demonstrated that there is an inverse relationship between lymphatic egress and inflammatory arthritis in affected joints. As a model, tumor necrosis factor (TNF)-transgenic mice develop advanced arthritis following draining lymph node (LN) collapse, and loss of lymphatic contractions downstream of inflamed joints. It is unknown if these lymphatic deficits are reversible. This study was undertaken to test the hypothesis that anti-TNF therapy reduces advanced erosive inflammatory arthritis, associated with restoration of lymphatic contractions, repair of damaged lymphatic vessels, and evidence of increased monocyte egress.

METHODS

TNF-transgenic mice with advanced arthritis and collapsed popliteal LNs were treated with anti-TNF monoclonal antibody (10 mg/kg weekly) or placebo for 6 weeks, and effects on knee synovitis, lymphatic vessel ultrastructure and function, and popliteal LN cellularity were assessed by ultrasound, histology, transmission electron microscopy (TEM), near-infrared indocyanine green imaging, and flow cytometry.

RESULTS

Anti-TNF therapy significantly decreased synovitis (∼5-fold; P < 0.05 versus placebo), restored lymphatic contractions, and significantly increased the number of popliteal LN monocyte/macrophages (∼2-fold; P < 0.05 versus placebo). TEM demonstrated large activated macrophages attached to damaged lymphatic endothelium in mice with early arthritis, extensively damaged lymphatic vessels in placebo-treated mice with advanced arthritis, and rolling leukocytes in repaired lymphatic vessels in mice responsive to anti-TNF therapy.

CONCLUSION

These findings support the concept that anti-TNF therapy ameliorates erosive inflammatory arthritis, in part via restoration of lymphatic vessel contractions and potential enhancement of inflammatory cell egress.

Rheumatoid arthritis

Rheumatoid arthritis is a chronic inflammatory joint disease, which can cause cartilage and bone damage as well as disability. Early diagnosis is key to optimal therapeutic success, particularly in patients with well-characterised risk factors for poor outcomes such as high disease activity, presence of autoantibodies, and early joint damage. Treatment algorithms involve measuring disease activity with composite indices, applying a treatment-to-target strategy, and use of conventional, biological, and newz non-biological disease-modifying antirheumatic drugs. After the treatment target of stringent remission (or at least low disease activity) is maintained, dose reduction should be attempted. Although the prospects for most patients are now favourable, many still do not respond to current therapies. Accordingly, new therapies are urgently required. In this Seminar, we describe current insights into genetics and aetiology, pathophysiology, epidemiology, assessment, therapeutic agents, and treatment strategies together with unmet needs of patients with rheumatoid arthritis.

Cartilage damage and bone erosion are more prominent determinants of functional impairment in longstanding experimental arthritis than synovial inflammation

Chronic inflammation of articular joints causing bone and cartilage destruction consequently leads to functional impairment or loss of mobility in affected joints from individuals affected by rheumatoid arthritis (RA). Even successful treatment with complete resolution of synovial inflammatory processes does not lead to full reversal of joint functionality, pointing to the crucial contribution of irreversibly damaged structural components, such as bone and cartilage, to restricted joint mobility. In this context, we investigated the impact of the distinct components, including synovial inflammation, bone erosion or cartilage damage, as well as the effect of blocking tumor necrosis factor (TNF) on functional impairment in human-TNF transgenic (hTNFtg) mice, a chronic inflammatory erosive animal model of RA. We determined CatWalk-assisted gait profiles as objective quantitative measurements of functional impairment. We first determined body-weight-independent gait parameters, including maximum intensity, print length, print width and print area in wild-type mice. We observed early changes in those gait parameters in hTNFtg mice at week 5 – the first clinical signs of arthritis. Moreover, we found further gait changes during chronic disease development, indicating progressive functional impairment in hTNFtg mice. By investigating the association of gait parameters with inflammation-mediated joint pathologies at different time points of the disease course, we found a relationship between gait parameters and the extent of cartilage damage and bone erosions, but not with the extent of synovitis in this chronic model. Next, we observed a significant improvement of functional impairment upon blocking TNF, even at progressed stages of disease. However, blocking TNF did not restore full functionality owing to remaining subclinical inflammation and structural microdamage. In conclusion, CatWalk gait analysis provides a useful tool for quantitative assessment of functional impairment in inflammatory destructive arthritis. Our findings indicate that cartilage damage and bone erosion, but not synovial inflammation, are the most important determinants for progressive functional impairment in this chronic erosive arthritis model.

Summary: Gait-profile assessment is an objective quantitative measurement to monitor functional impairment in arthritis models. Longstanding functional impairment correlates with inflammation-driven structural damage.

Effect of denosumab on Japanese patients with rheumatoid arthritis: a dose-response study of AMG 162 (Denosumab) in patients with RheumatoId arthritis on methotrexate to Validate inhibitory effect on bone Erosion (DRIVE)-a 12-month, multicentre, randomised, double-blind, placebo-controlled, phase II clinical trial

Objectives

To evaluate efficacy and safety of three different regimens of denosumab, a fully human monoclonal antibody to receptor activator of nuclear factor kappa B (RANK) ligand (RANKL), for Japanese patients with rheumatoid arthritis (RA).

Methods

In this multicentre, randomised, placebo-controlled phase II study, 350 Japanese patients with RA between 6 months and <5 years, stratified by glucocorticoid use and rheumatoid factor status, were randomly assigned to subcutaneous injections of placebo or denosumab 60 mg every 6 months (Q6M), every 3 months (Q3M) or every 2 months (Q2M). All patients basically continued methotrexate treatment and had a supplement of calcium and vitamin D throughout the study. The primary endpoint was change in the modified Sharp erosion score from baseline to 12 months.

Results

Denosumab significantly inhibited the progression of bone erosion at 12 months compared with the placebo, and the mean changes of the modified Sharp erosion score at 12 months from baseline were 0.99, 0.27 (compared with placebo, p=0.0082), 0.14 (p=0.0036) and 0.09 (p<0.0001) in the placebo, Q6M, Q3M and Q2M, respectively. Secondary endpoint analysis revealed that denosumab also significantly inhibited the increase of the modified total Sharp score compared with the placebo, with no obvious evidence of an effect on joint space narrowing for denosumab. As shown in previous studies, denosumab increased bone mineral density. No apparent difference was observed in the safety profiles of denosumab and placebo.

Conclusions

Addition of denosumab to methotrexate has potential as a new therapeutic option for patients with RA with risk factors of joint destruction.

Trial registration number

JapicCTI-101263.

Effects of low-intensity non-coherent light therapy on the inflammatory process in the calcaneal tendon of ovariectomized rats

The aim of this experimental study was to investigate the effects of low-intensity light-emitting diode (LED) phototherapy on the inflammatory process in the calcaneal tendon of ovariectomized rats (OVX) through the involvement of the inflammatory mediators interleukin (IL)-6, IL-10, and tumor necrosis factor-alpha (TNF-α). Thirty-five female Wistar rats were divided into 4 groups: 3 groups of OVX rats totaling 30 rats (untreated OVX rats [OVX injury group], treated OVX rats [OVX LED group], and control OVX rats; subgroups existed based on the sampling times, which were 3, 7, and 14 days) and 1 group of non-OVX rats (not OVX; n = 5). Tendon injury was induced by trauma using a 208-g mass placed at 20 cm from the right tendon of each animal with energy of 0.70 J. The animals were treated 12 h after tendonitis with LED therapy and every 48 h thereafter until euthanasia (at 3, 7, or 14 days). The tendons were dissected and stored in liquid nitrogen at -196 °C, thawed only at the time of immunoenzymatic testing (ELISA). Groups treated with LED showed a decrease in the number of pro-inflammatory cells, IL-6, and TNF-α (p <0.05), and an increase in IL-10 (p < 0.05) when compared to the not OVX group (p < 0.05). It was concluded that low-intensity LED treatment using the parameters and wavelength of 945 nm in the time periods studied reduced the release of IL-6 and TNF-α and increased the release of IL-10, thereby improving the inflammatory response in OVX rats.

Regulatory T cell-deficient scurfy mice develop systemic autoimmune features resembling lupus-like disease

Introduction

Scurfy mice are deficient in regulatory T cells (Tregs), develop a severe, generalized autoimmune disorder that can affect almost every organ and die at an early age. Some of these manifestations resemble those found in systemic lupus erythematosus (SLE). In addition, active SLE is associated with low Treg numbers and reduced Treg function, but direct evidence for a central role of Treg malfunction in the pathophysiology of lupus-like manifestations is still missing. In the present study, we characterize the multiorgan pathology, autoantibody profile and blood count abnormalities in scurfy mice and show their close resemblances to lupus-like disease.

Methods

Scurfy mice have dysfunctional Tregs due to a genetic defect in the transcription factor Forkhead box protein 3 (Foxp3). We analyzed skin, joints, lung and kidneys of scurfy mice and wild-type (WT) controls by conventional histology and immunofluorescence (IF) performed hematological workups and tested for autoantibodies by IF, immunoblotting and enzyme-linked immunosorbent assay. We also analyzed the intestines, liver, spleen and heart, but did not analyze all organs known to be affected in scurfy mice (such as the testicle, the accessory reproductive structures, the pancreas or the eyes). We transferred CD4⁺ T cells of scurfy or WT mice into T cell-deficient B6/nude mice.

Results

We confirm previous reports that scurfy mice spontaneously develop severe pneumonitis and hematological abnormalities similar to those in SLE. We show that scurfy mice (but not controls) exhibited additional features of SLE: severe interface dermatitis, arthritis, mesangioproliferative glomerulonephritis and high titers of anti-nuclear antibodies, anti-double-stranded DNA antibodies, anti-histone antibodies and anti-Smith antibodies. Transfer of scurfy CD4⁺ T cells (but not of WT cells) induced autoantibodies and inflammation of lung, skin and kidneys in T cell-deficient B6/nude mice.

Conclusion

Our observations support the hypothesis that lupus-like autoimmune features develop in the absence of functional Tregs.

Rheumatoid arthritis therapy reappraisal: strategies, opportunities and challenges

Rheumatoid arthritis (RA) is considered a chronic disease that cannot be cured. Biologic agents have enabled good therapeutic successes; however, the response to biologic therapy depends on treatment history and, especially, disease duration. In general, the more drug-experienced the patients, the lower the response rates, although this limitation can be overcome by promptly adjusting or switching treatment in a treat-to-target approach. Another challenge is the question of how long therapy should be continued once the treatment target, which should be remission or at least a state of low disease activity, has been reached. The data available suggest that, in most patients with established disease, cessation of biologic therapy will be followed by disease flares, whereas a reduction of dose or an increase in the interval between doses enables maintenance of treatment success. Induction therapy very early in the disease course followed by withdrawal of the biologic agent might also be a feasible approach to attain sustained good outcomes, but currently available data are not strong enough to allow for such a conclusion to be reached. Taken together, this underscores the importance of research into the cause(s) of RA so that curative therapies can be developed.

The low level laser therapy (LLLT) operating in 660 nm reduce gene expression of inflammatory mediators in the experimental model of collagenase-induced rat tendinitis

Tendinopathy is a common disease with a variety of treatments and therapies. Laser therapy appears as an alternative treatment. Here, we investigate the effects of laser irradiation in an experimental model of tendinitis induced by collagenase injection on rats' Achilles tendon, verifying its action in important inflammatory markers. Male Wistar rats were used and divided into five groups: control saline (C), non-treated tendinitis (NT) and tendinitis treated with sodium diclofenac (D) or laser (1 J) and (3 J). The tendinitis was induced by collagenase (100 μg/tendon) on the Achilles tendon, which was removed for further analyses. The gene expression for COX-2; TNF-α; IL-6; and IL-10 (RT-PCR) was measured. The laser irradiation (660 nm, 100 mW, 3 J) used in the treatment of the tendinitis induced by collagenase in Achilles tendon in rats was effective in the reduction of important pro-inflammatory markers such as IL-6 and TNF-α, becoming a promising tool for the treatment of tendon diseases.

Human secreted stabilin-1-interacting chitinase-like protein aggravates the inflammation associated with rheumatoid arthritis and is a potential macrophage inflammatory regulator in rodents

OBJECTIVE

To study the relationship between the human secreted protein stabilin-1-interacting chitinase-like protein (SI-CLP) and rheumatoid arthritis (RA).

METHODS

The expression of SI-CLP in peripheral blood mononuclear cells (PBMCs) and synovial fluid from patients with RA and the effects of cytokines on SI-CLP expression were examined by Western blotting. Fluorescence-activated cell sorting analysis was performed to investigate the binding between SI-CLP and cells. Bone marrow-derived macrophages were isolated from wild-type and SI-CLP(-/-) mice, and real-time quantitative polymerase chain reaction was performed to detect the levels of messenger RNA for cytokines or SI-CLP in SI-CLP- or cytokine-treated macrophages. Histologic studies were conducted to evaluate inflammation and the expression of interleukin-12 (IL-12), IL-13, and SI-CLP in lesions. Enzyme-linked immunosorbent assays were used to detect the cytokine levels in bone marrow-derived macrophages. Rats or mice with collagen-induced arthritis (CIA) and SI-CLP(-/-) mice were used to study the function of SI-CLP in RA.

RESULTS

SI-CLP expression was increased in PBMCs and detectable in synovial fluid from patients with RA. Administration of SI-CLP to rats with CIA aggravated arthritis-associated inflammation. SI-CLP was specifically attached to the surface protein of macrophages, which elevated the expression of IL-1β, IL-6, IL-12, and IL-13 in macrophages and mouse bone marrow-derived macrophages, up-regulating ERK phosphorylation. Moreover, SI-CLP was up-regulated by both IL-12 and IL-13 through JNK and JAK/STAT signaling, respectively. Knockout of SI-CLP resulted in a decrease in the expression of IL-1β, IL-6, IL-12, and IL-13 and lower susceptibility to CIA compared with wild-type mice. SI-CLP treatment also aggravated arthritis-related inflammation in wild-type and SI-CLP(-/-) mice.

CONCLUSION

SI-CLP functions as a regulator of the inflammatory response by macrophages. The decrease in inflammation-associated cytokine levels resulting from SI-CLP knockout may explain the lower susceptibility to CIA in SI-CLP(-/-) mice.

Pristane-induced lupus as a model of human lupus arthritis: evolvement of autoantibodies, internal organ and joint inflammation

OBJECTIVE

Arthritis is frequently seen in human lupus, but rarely in lupus models. Pristane-induced lupus (PIL) can be induced in various mouse strains such as BALB/c and C57BL/6. We herein characterize clinical and histological features of arthritis in the context of systemic lupus and provide a prudent comparison with models of rheumatoid arthritis (RA).

METHODS

A total of 57 BALB/c mice received pristane (PIL group) and were analyzed for serum autoantibodies (anti-chromatin-, -histone, -Sm, -dsDNA), as well as for clinical features and histopathology of joints, lungs and kidneys. Joint pathology was quantified by image analysis and tissue cytometry. Ten C57BL/6 mice (Bl/6-PIL) and historical groups of two different RA models were analyzed accordingly.

RESULTS

In BALB/c PIL, clinical arthritis started at three months, occurred finally in 79% of PIL (but not in controls, p<0.001) and correlated with areas of inflammation, erosion, cartilage damage, osteoclast numbers and total severity score (for all: r>0.7, p<0.001). After eight months, 58% of PIL (but no controls, p<0.001) had mild-erosive arthritis. In contrast to RA, the most frequent inflammatory cell type of the pannus was granulocytes (17.7%), PIL had lower numbers of osteoclasts, erosions rarely affected both layers of the cortical bone and there was no progression to complete joint destruction (even after one year of observation). Serum autoantibodies (auto-abs) preceded arthritis and became significantly elevated in all PIL; affected joints showed increased deposits of IgG (and IgM) within the inflammatory tissue, indicative of an ab-mediated process. PIL mice with arthritis also showed signs of pulmonary (100%) and renal (46%) lupus. In contrast to BALB/c, Bl/6-PIL mice did not develop any signs of arthritis.

CONCLUSION

PIL in BALB/c mice is characterized by severe organ involvement, typical autoabs and by a mild-erosive arthritis with similarities to, but also with distinct differences from, RA. PIL may help to study arthritis along with other key features of systemic lupus erythematosus after therapeutic interventions or in knock-out models based on a BALB/c but not on a C57BL/6 background.

Efficacy of B cell depletion therapy for murine joint arthritis flare is associated with increased lymphatic flow

OBJECTIVE

B cell depletion therapy ameliorates rheumatoid arthritis by mechanisms that are incompletely understood. Arthritis flare in tumor necrosis factor (TNF)-transgenic mice is associated with efferent lymph node (LN) "collapse," triggered by B cell translocation into lymphatic spaces and decreased lymphatic drainage. The aim of this study was to examine whether the efficacy of B cell depletion therapy is associated with restoration of lymphatic drainage due to removal of obstructing nodal B cells.

METHODS

We used contrast-enhanced magnetic resonance imaging, indocyanine green near-infrared imaging, and intravital immunofluorescence imaging to longitudinally assess synovitis, lymphatic flow, and cell migration in lymphatic vessels in TNF-transgenic mice. We conducted tests to determine whether the efficacy of B cell depletion therapy is associated with restoration of lymphatic draining and cell egress from arthritic joints.

RESULTS

Unlike active lymphatics to normal and prearthritic knees, afferent lymphatic vessels to collapsed LNs in inflamed knees do not pulse. Intravital immunofluorescence imaging demonstrated that CD11b+ monocyte/macrophages in lymphatic vessels afferent to expanding LNs travel at high velocity (mean±SD 186±37 μm/second), while these cells are stationary in lymphatic vessels afferent to collapsed popliteal LNs. B cell depletion therapy for arthritis flares in TNF-transgenic mice significantly decreased knee synovium volume (by 50% from the baseline level) and significantly increased lymphatic clearance compared with placebo (P<0.05). This increased lymphatic drainage restored macrophage egress from inflamed joints without recovery of the lymphatic pulse.

CONCLUSION

These results support a novel mechanism in which B cell depletion therapy for joint arthritis flares lessens inflammation by increasing lymphatic drainage and subsequent migration of cells and cytokines from the synovial space.

Bone erosion in rheumatoid arthritis: mechanisms, diagnosis and treatment

Bone erosion is a central feature of rheumatoid arthritis and is associated with disease severity and poor functional outcome. Erosion of periarticular cortical bone, the typical feature observed on plain radiographs in patients with rheumatoid arthritis, results from excessive local bone resorption and inadequate bone formation. The main triggers of articular bone erosion are synovitis, including the production of proinflammatory cytokines and receptor activator of nuclear factor κB ligand (RANKL), as well as antibodies directed against citrullinated proteins. Indeed, both cytokines and autoantibodies stimulate the differentiation of bone-resorbing osteoclasts, thereby stimulating local bone resorption. Although current antirheumatic therapy inhibits both bone erosion and inflammation, repair of existing bone lesions, albeit physiologically feasible, occurs rarely. Lack of repair is due, at least in part, to active suppression of bone formation by proinflammatory cytokines. This Review summarizes the substantial progress that has been made in understanding the pathophysiology of bone erosions and discusses the improvements in the diagnosis, monitoring and treatment of such lesions.

A dynamic real time in vivo and static ex vivo analysis of granulomonocytic cell migration in the collagen-induced arthritis model

Neutrophilic granulocytes and monocytes (granulomonocytic cells; GMC) drive the inflammatory process at the earliest stages of rheumatoid arthritis (RA). The migratory behavior and functional properties of GMC within the synovial tissue are, however, only incompletely characterized. Here we have analyzed GMC in the murine collagen-induced arthritis (CIA) model of RA using multi-photon real time in vivo microscopy together with ex vivo analysis of GMC in tissue sections.GMC were abundant as soon as clinical arthritis was apparent. GMC were motile and migrated randomly through the synovial tissue. In addition, we observed the frequent formation of cell clusters consisting of both neutrophilic granulocytes and monocytes that actively contributed to the inflammatory process of arthritis. Treatment of animals with a single dose of prednisolone reduced the mean velocity of cell migration and diminished the overall immigration of GMC.In summary, our study shows that the combined application of real time in vivo microscopy together with elaborate static post-mortem analysis of GMC enables the description of dynamic migratory characteristics of GMC together with their precise location in a complex anatomical environment. Moreover, this approach is sensitive enough to detect subtle therapeutic effects within a very short period of time.

Joint appendages: the structures which have historically been overlooked in arthritis research and therapy development

Rheumatologists have largely conceptualised joint disease in inflammatory and degenerative arthritis in terms of bone, cartilage and the synovial lining, but have tended to overlook other integral components of the joints which are attached close to joint margins. We discuss these structures under the umbrella term of 'appendages'. These structures include ligaments, tendons, entheses or joint insertions, regional fibrocartilages, bursae and other peri-articular joint structures including fat pads and nails. In this review, we highlight how these structures play key pathophysiological roles in inflammatory arthritis and we emphasise how an understanding of these structures is collectively important for both clinical practice and future rheumatological research.

Vascular endothelial growth factor C attenuates joint damage in chronic inflammatory arthritis by accelerating local lymphatic drainage in mice

OBJECTIVE

To investigate whether the enhancement of joint lymphangiogenesis by injection of vascular endothelial growth factor C (VEGF-C) adeno-associated virus (AAV) into the affected joints has therapeutic efficacy in chronic inflammatory arthritis in mice.

METHODS

Tumor necrosis factor-transgenic (TNF-Tg) mice were used as a model of chronic inflammatory arthritis. Human VEGF-C was cloned into an AAV expression vector to generate AAV-VEGF-C. The joints of TNF-Tg mice were injected with AAV-VEGF-C or AAV-luciferase (AAV-Luc) as a control. During the 4 months following injection, magnetic resonance imaging of the joints and lymphatic imaging were performed to assess changes in synovial volume and lymph flow from the joint tissues to local draining lymph nodes. Joint inflammation, bone erosion, and cartilage loss were examined by histologic analyses. Lymphatic vessel formation was assessed using immunohistochemistry.

RESULTS

Intraarticular administration of AAV-VEGF-C virus significantly attenuated the increase in synovial volume and increased lymphatic vessel number in the joint sections, as compared with that in control AAV-Luc-injected joints, during the 4-month period. This was accompanied by a reduction in the area of inflammation, bone erosion, cartilage loss, and osteoclast numbers. Lymph flow from the joints to local draining lymph nodes was slower in TNF-Tg mice than in wild-type littermates, and was significantly improved with AAV-VEGF-C treatment.

CONCLUSION

Intraarticular injection of AAV-VEGF-C increased lymphangiogenesis and improved lymphatic drainage from the inflamed joints of mice, resulting in attenuation of joint tissue damage. Thus, improvement of joint lymphatic function by local administration of lymphatic growth factors represents a new therapeutic approach for chronic inflammatory arthritis.

Early treatment in early undifferentiated arthritis

The early diagnosis of new-onset rheumatoid arthritis (RA) has become a major objective for rheumatologists in order to identify a management strategy able to change the natural history of the disease and to prevent joint damage and functional impairment. Emergent evidence emphasizes the benefits of early aggressive therapy of RA. By the nineties, early arthritis cohorts have been collected throughout the world with the aim to increase the early referral of patients with early onset disease by the general practitioners and to collect data on the development of full-blown RA. The frequency of undifferentiated arthritis (UA) ranged from 23% to 81% in these early cohorts with most of them reporting a rate of 30%. The transition rate from UA to RA was between 13% and 54%. A percentage of 20-60% of patients with UA had a self-limiting disease. Our article deals with the controversy existing in the management of UA. Should every patient with UA be treated? Could patients with a favorable disease course be exposed to unnecessary risk with initiation of aggressive therapy with synthetic disease-modifying anti-rheumatic drugs (DMARDs) or biologic agents? The pros and cons of treating patients with UA are examined.