Proof of concept: enthesitis and new bone formation in spondyloarthritis are driven by mechanical strain and stromal cells

Global research trends in biological therapy for ankylosing spondylitis: A comprehensive visualization and bibliometric study (2004-2023)

Ankylosing spondylitis (AS) is a chronic inflammatory disease primarily affecting the spine and pelvic bones. Recently, many researchers have confirmed that biological therapy is effective for AS patients, which provides a new perspective for the treatment of AS. This study aimed to evaluate the characteristics of scientific research on AS and biological therapy worldwide and investigate research hotspots and the direction of future trends. Global literature on AS and biological therapy published from 2004 to 2023 was searched in the Web of Science, Scopus, and PubMed databases. Visualization and bibliometric analysis were carried out using the VOSviewer and CiteSpace software with the retrieved data regarding countries, institutions, journals, authors, and keywords. A total of 2,243 related articles were included, showing that the number of articles in this field has increased annually. The highest number of articles were from the USA (24.39%), followed by Italy (14.36%), England (12.19%), Germany (10.66%), and Spain (7.86%). Braun J was the most prolific author, with a h-index of 16. The institution with the most articles was Charite Universitatsmedizin Berlin, and the Rheumatology journal had the highest number of publications. "janus kinase inhibitor" and "secukinumab" displayed a notable citation burst in recent years, indicating IL-17i and JAKi are research hotspots. More and more attention has been paid to the association between AS and biological therapy in the past two decades. The USA plays a leading role, and China has made remarkable progress. This study has provided a valuable reference for future research in this field.

Development of a Mouse Model of Enthesis-Specific NF-κB Activation

Enthesitis, or inflammation specific to sites in the body where tendon inserts into bone, can arise in isolated joints from overuse or in multiple joints as a complication of an autoimmune condition such as psoriatic arthritis or spondyloarthritis. However, the pathogenesis of enthesitis is not well understood, so treatment strategies are limited. A clinically relevant animal model of enthesitis would allow investigators to determine mechanisms driving the disease and evaluate novel therapies. Therefore, we developed a murine model of inducible enthesis-specific inflammation by constitutively activating the NF-κB pathway in Gli1+ cells. Gli1CreERT mice were crossed with IKKβ-overexpression mice and given tamoxifen injections 5 days postnatally to induce enthesitis. Sixteen weeks of IKKβ overexpression in enthesis cells led to impaired mechanical properties, subtle histologic changes, and changes to expression of extracellular matrix- and inflammation-related genes. Increased loading from treadmill overuse activity did not exacerbate this phenotype. Clinical significance: The new murine model may have utility for studying the pathogenesis of enthesitis and approaches to treat the condition.

The association between physical trauma and autoimmune articular and dermatological disorders

OBJECTIVE

This review investigates the association between physical trauma and the onset and progression of various inflammatory diseases, including psoriatic arthritis (PsA), rheumatoid arthritis (RA), spondyloarthropathies (SpA), and Familial Mediterranean Fever (FMF). In addition, we will refer to the linkage between physical injury and skin manifestations in patients with psoriasis, sarcoidosis and systemic sclerosis. The aim is to summarize the current evidence and explore the potential mechanisms through which trauma may affect these conditions.

METHODS

A detailed literature review was conducted, focusing on studies linking physical trauma with the development of psoriasis, SpA, PsA, RA, FMF, systemic sclerosis and sarcoidosis. The review includes observational data, case reports, and experimental studies that highlight the impact of trauma on disease initiation and exacerbation.

RESULTS

Physical trauma is implicated in the pathogenesis of several dermatological and rheumatological conditions. Biomechanical stress and microdamage at entheses contribute to the development of SpA. In PsA, trauma is associated with the onset of enthesitis and arthritis, supported by increased prevalence in affected patients and is often regarded as "deep Koebner phenomenon". The Koebner phenomenon links skin trauma with psoriasis, where new lesions appear at injury sites. RA shows a notable association with physical trauma, with retrospective studies suggesting that trauma can trigger disease onset, although the exact mechanisms remain unclear. The concept of the synovio-entheseal complex is discussed in order to elucidate how mechanical stress and immune responses interplay in SpA. Physical exertion or injury might precipitate FMF attacks, though existing data remain limited. Sarcoidosis has been linked to tattoo-related trauma, suggesting a potential role of localized injury in sarcoid-like reactions. Several case reports describe the occurrence of dermatologic manifestations of scleroderma, including morphea in patients with localized disease and perifollicular hypopigmentation in patients with systemic sclerosis.

CONCLUSION

This review consolidates current evidence on the relationship between physical trauma and various inflammatory conditions, emphasizing the need for further research to fully understand these connections. These findings highlight the importance of considering trauma in the clinical management of these diseases and suggest avenues for future investigation.

Enthesitis on Chip - A Model for Studying Acute and Chronic Inflammation of the Enthesis and its Pharmacological Treatment

Enthesitis, the inflammation of the enthesis, which is the point of attachment of tendons and ligaments to bones, is a common musculoskeletal disease. The inflammation often originates from the fibrocartilage region of the enthesis as a consequence of mechanical overuse or -load and consequently tissue damage. During enthesitis, waves of inflammatory cytokines propagate in(to) the fibrocartilage, resulting in detrimental, heterotopic bone formation. Understanding of human enthesitis and its treatment options is limited, also because of lacking in vitro model systems that can closely mimic the pathophysiology of the enthesis and can be used to develop therapies. In this study, an enthes(it)is-on-chip model is developed. On opposite sides of a porous culture membrane separating the chip's two microfluidic compartments, human mesenchymal stromal cells are selectively differentiated into tenocytes and fibrochondrocytes. By introducing an inflammatory cytokine cocktail into the fibrochondrocyte compartment, key aspects of acute and chronic enthesitis, measured as increased expression of inflammatory markers, can be recapitulated. Upon inducing chronic inflammatory conditions, hydroxyapatite deposition, enhanced osteogenic marker expression and reduced secretion of tissue-related extracellular matrix components are observed. Adding the anti-inflammatory drug celecoxib to the fibrochondrocyte compartment mitigates the inflammatory state, demonstrating the potential of the enthesitis-on-chip model for drug testing.

Sonoanatomy of the Finger Synovio-Entheseal Complexes

OBJECTIVES

The objectives of this ultrasound and anatomical study were: (1) To evaluate the reliability of ultrasound identification of the enthesis of the central slip of the extensor digitorum tendon (CSET) using cadaver specimens; (2) To assess the concordance of the measurement of the CSET thickness by ultrasound and gross anatomy; (3) To evaluate the variation in ultrasound identification of the CSET enthesis in a cadaveric experimental model of PIP synovitis.

METHODS

Four rheumatologist ultrasonographers blindly and independently measured by ultrasound the CSET enthesis thickness in the second to fifth fingers of 8 hands from fresh-frozen human cadavers in two rounds. These fingers were dissected and the thickness of the CSET measured by the anatomist. In addition, an artificial synovitis was created in the proximal interphalangeal (PIP) joints of a different cadaveric hand. The ultrasonographic CSET enthesis thickness was measured by the four investigators before and after intra-articular ultrasound guided injection of material.

RESULTS

Intra- and inter-observer reliability of CSET enthesis thickness measurement were good to excellent (ICC 0.93 for intra-observer agreement and 0.89-0.92 for inter-observer agreement). Ultrasound measurements were consistent and only slightly smaller than the anatomical ones (µ = -0.039 mm). The differences between the measurements of CSET enthesis thickness before and after the synovitis model were not statistically significant.

CONCLUSION

Ultrasound demonstrated high multiobserver reliability and agreement with gross anatomy in identifying the CSET enthesis and discriminated it from the capsular tissue of the PIP. Furthermore, an experimental model of PIP synovitis did not interfere with its identification.

Voluntary exercise in mice triggers an anti-osteogenic and pro-tenogenic response in the ankle joint without affecting long bones

Biomechanical stimulation is proposed to occupy a central place in joint homeostasis, but the precise contribution of exercise remains elusive. We aimed to characterize in vivo the impact of mechanical stimulation on the cell-controlled regulation of ossification within the ankles of healthy mice undergoing mild physical activity. DBA/1 male mice were subjected to voluntary running exercise for two weeks, and compared to mice housed in standard conditions (n = 20 per group). Free access to activity wheels resulted in a running exercise of 5.5 ± 0.8 km/day at 14.5 ± 0.5 m/min. Serum levels of alkaline phosphatase, IL-6, IL-8/Kc, IL-17a, and TNF-α were measured. No change in systemic inflammation was detected. The bone architecture of the femur and the calcaneus was unchanged, as revealed by μCT and histology of the enthesis of the Achilles tendon. mRNAs were extracted from femurs, tibias, and ankle joints before RT-qPCR analysis. The expression of the mechanosensitive genes Sclerostin (Sost) and Periostin (Postn) was not impacted by the exercise in long bones. Oppositely, Sost and Postn levels were modulated by exercise in joints, and osteogenic markers (Col10a1, Runx2, Osx, and Dmp1) were downregulated in the exercise group. In addition, the tenogenic markers Scx, Mkx, and Tnmd were upregulated by exercise. Thus, voluntary exercise affected the phenotype of joint cells without impacting long bones. As gene expression of Bmp2, Bmp4, and Id1 was also reduced in these cells, an off-regulation of BMP signaling could be partly responsible for their mechanosensitive response. Running exercise seemed to preserve the tendon from its progressive ossification, as seen in numerous enthesopathies. This study paves the way to future experiments for investigating the effects of mechanical stimulation in various mouse models.

The influence of age, biological sex, anthropometrics, and neck characteristics on external occipital protuberance size

BACKGROUND

40-45 % of the population presents with enlarged external occipital protuberances (EEOPs), which can lead to pain. EEOP occurrence is higher in younger males; however, the reason is debated. We used plane lateral radiographs to investigate how anthropometrics, age, biological sex, head and neck kinematics, and neck strength differ between those with and without an EEOP.

METHODS

Data was compiled across four study samples, which included lateral radiographs taken in a neutral neck posture (n = 102, 50% females). An enlarged EOP was defined as being longer than 10 mm, and this threshold was used to classify participants as having a presence or absence of an EEOP. Statistical analyses were used to compare outcome measures between those with and without an EEOP presence for age, biological sex, skull angle, intervertebral joint angle (C1-C2 through C6-C7), and neck strength (flexion and extension).

RESULTS

Twenty-four percent of participants (19 males and five females, p = 00.002 for biological sex differences) presented with an EEOP; only one was over 30 years old. There were no significant main effects on the skull and intervertebral joint angles, participant anthropometrics, or neck strength.

CONCLUSIONS

This study confirmed that enlarged EOPs are more prevalent in males; however, neck posture and other anthropometrics do not differ with the presence or absence of an EEOP.

Pelvic parameters as prognostic factors of radiographic progression in classical Ankylosing Spondylitis: A prospective follow-up data

Radiographic progression in Ankylosing spondylitis (AS) is driven by mechanical strain. A well-balanced spine provides a favorable weight distribution across the entheses. Pelvic parameters are useful in assessing the shape of the spine. The present study aimed to prospectively investigate the predictive value of pelvic parameters for radiographic progression in AS. This non-interventional, observational, and prospective study enrolled AS patients fulfilling the modified New York criteria (mNY) currently under follow-up in the MARS (MARmara Spondyloarthritis) outpatient clinics. The primary objective was to investigate the relationship between the baseline pelvic parameters and radiographic progression in the spine. Two trained radiologists (EB, OB) independently assessed the modified Stoke Ankylosing Spondylitis Spine Score (mSASSS). An orthopedic surgeon (AHA) and a radiologist (EB) derived the pelvic parameters. Patients with no bridging or bamboo spine were included in the final analysis. Risk assessment for radiographic progression, defined as a two-unit increase in mSASSS or developing a new syndesmophyte every two years, was done using uni- and multivariate logistic regression analyses. Radiographs of 69 AS patients were analyzed. The median (IQR 25-75) prospective follow-up was 47.7 (34.6-52.8) months. Only 33.3% (23/69) had radiographic progression. The pelvic tilt (PT) was lower in patients with radiographic progression (p = 0.037) and each degree of decrease in PT provided a 9% increase in risk for radiographic progression. Male patients were 7.5 times more likely to progress. Pelvic parameters provide a prognostic insight into the radiographic progression in AS. Our observations may aid in selecting patient-specific interventions in addition to anti-inflammatory treatments.

Impact of blue-collar vs. white-collar occupations on disease burden in psoriatic arthritis patients: A Swiss clinical quality management in rheumatic diseases cohort study

Biomechanical stress may exacerbate inflammation in psoriatic arthritis (PsA). This study aimed to investigate disease activity, work disability, and drug response/retention rates in PsA patients among two different occupation's types: blue-collar workers (BCol) with manual labor versus white-collar workers (WCol) with sedentary occupations. PsA patients registered in the Swiss cohort (SCQM) were classified as BCol or WCol workers and assessed at the initiation of a biologic or targeted synthetic disease-modifying anti-rheumatic drug (b-/tsDMARD). We compared the baseline characteristics at treatment start and the DAS28-CRP for the 1-year remission. Treatment retention was investigated using Kaplan-Meier curves and Cox regression analysis. Multivariable models were adjusted for potential confounders. Of 564 patients, 29% were BCol, and 71% were WCol workers. Baseline disease activity was comparable between both groups. BCol workers were predominantly male (79.8%) and more work disabled at baseline (84.0% vs. 27.9%; p < 0.01). One hundred seventy-four treatment courses (TCs) of 165 PsA patients were included for longitudinal analysis. Occupation did not significantly influence the achievement of DAS28-CRP remission at 1 year. Kaplan-Meier analysis (n = 671) indicated longer retention for BCol workers (mean retention duration: 3.15 years vs. 2.15 years, (p = 0.006). However, adjusted Cox regression analysis did not corroborate these findings. This study indicates that physically demanding occupations correlate with increased rates of work disability among PsA patients, while treatment response seems to be unaffected by the patients' occupation type. Additional research is required to thoroughly comprehend the relationship between physical workload, disease activity, and treatment outcomes. Key Points • This study indicates that physically demanding occupations correlate with increased rates of work disability among PsA patients. • The treatment response among of PsA patients seems unaffected by the patients' occupation type.

GRAPPA 2023 Debate: Is Psoriatic Disease Really a Primary Enthesitis That Drives Joint Synovitis? The Enthesitis Hypothesis 25 Years On

The enthesitis hypothesis posits that enthesitis is a primary lesion and that inflammation at the enthesis initiates the musculoskeletal symptoms of psoriatic arthritis (PsA) and spondyloarthropathies (SpA). The hypothesis suggested that inflamed entheseal tissue near the synovium could trigger cytokine-mediated synovitis, that enthesis bone anchorage could explain osteitis, and that the location of entheses at the soft tissue interface could explain dactylitis. Advances in imaging techniques that allow better visualization of enthesitis lesions and the development of animal models have allowed evolution of the concept of enthesitis as a central mechanistic driver of musculoskeletal symptoms in PsA and SpA. A debate between Drs. Dennis McGonagle and Bruce Kirkham at the Group for Research on Psoriasis and Psoriatic Arthritis (GRAPPA) 2023 annual meeting discussed the data supporting and refuting this hypothesis in PsA and SpA, respectively. The major points of this debate are summarized in this article.

The Challenge of IBD-Related Arthritis Screening Questionnaires in Early and Predominantly Entheseal Phenotypes

INTRODUCTION

Inflammatory bowel disease (IBD)-related arthritis is recognized as the most prevalent extraintestinal manifestation (EIM) of IBD. The objective of this study was to determine the prevalence and characteristics of undiagnosed IBD-related arthritis and to compare two screening questionnaires, DETection of Arthritis in Inflammatory boweL diseases (DETAIL) and IBd Identification of Spondyloarthritis Questionnaire (IBIS-q), for early disease detection.

METHODS

Between April and October 2023, both the DETAIL and IBIS-q questionnaires were administered to consecutive IBD outpatients visiting the University Hospital of Udine, Italy. During routine gastroenterology evaluations, patients aged > 18 years with Crohn's disease (CD) or ulcerative colitis (UC) were requested to complete both questionnaires. Subsequently, all patients who completed the questionnaires underwent a blinded rheumatological evaluation within 2 weeks. Patients with a previous diagnosis of IBD-related SpA were then excluded.

RESULTS

Overall, 203 patients were enrolled, of whom 26 were excluded because of a prior diagnosis of inflammatory arthritis. Among the remaining 177 patients, 10/177 (5.6%) received a new diagnosis of IBD-related arthritis. The median duration of symptoms before diagnosis was 4 (IQR 1.8-10.5) months. Imaging-confirmed enthesitis was the predominant pattern in 8 out 10 cases (80%, with 8 out 8 lacking concomitant peripheral arthritis), axial involvement in 1 out 10 cases (10%), and peripheral arthritis in 1 out 10 cases (10%). The DETAIL questionnaire exhibited higher specificity, but lower sensitivity compared to the IBIS-q, with a sensitivity of 40.0% (12.2-73.8) and specificity of 84.4% (78.0-89.6) versus a sensitivity of 70.0% (34.8-93.3) and specificity of 74.3% (66.9-80.7). Both questionnaires performed less effectively than in other studies.

CONCLUSION

This study highlights a significant proportion of undiagnosed IBD-related arthritis (5.6%). Enthesitis emerged as the predominant pattern of newly diagnosed arthritis in our cohort, likely due to the recent onset of symptoms. Our study underscores the importance of entheseal involvement in early IBD-related arthritis and the importance of incorporating entheseal involvement into screening questionnaires.

A higher body mass index and increased syndesmophytes volume are associated with facet joints ankylosis on thoracic spine in patients with ankylosing spondylitis: a retrospective cohort study

OBJECTIVE

To investigate the association between syndesmophytes and facet joint (FJ) lesions in patients with ankylosing spondylitis (AS), and to identify clinical factors associated with FJ ankylosis (FJA) in thoracic segment.

METHODS

Ninety-seven patients with AS who underwent thoracic spine computed tomography (CT) or chest CT and without completely thoracic spine fusion were included. FJ lesions were analyzed for the numbers and distribution of normal, ankylosis, erosions, joint-space narrowing, osteophytes, and subchondral sclerosis. The volume of vertebral syndesmophtes unit (VSU) and total thoracic syndesmophtes volume were separately calculated by Mimics software. Clinical factors associated with FJA were investigated using generalized estimation equation (GEE). The association between syndesmophtes volume and numbers of FJ structural lesions was analyzed using generalized additive mixed model (GAMM).

RESULTS

2328 FJ and 1164 VSUs in thoracic spine were assessed. The majority FJ structural lesions were ankylosis (32.39%). FJA was more frequently seen in vertebrae with syndesmophytes formation (p < 0.001). GEE showed that patients with normal BMI (18.5-24.9 kg/m2) and high BMI (> 24.9 kg/m2) were more likely to have FJA in thoracic spine (odds rations [95% confidence interval]: 0.27(0.12-0.59), 1.45(1.03-8.57), respectively). GAMM showed that syndesmophytes volume increase the numbers of FJA (standard β = 0.009, p < 0.05) and decreased the numbers of normal FJ (standard β = -0.07, p < 0.01).

CONCLUSION

FJA was the most common FJ structural lesion in thoracic spine, and it increases linearly with syndesmophytes before the bridging syndesmophytes formed. A higher BMI (especially > 24.9 kg/m2) and increased syndesmophytes volume are associated with FJA in thoracic spine.

Unveiling Metabolic Similarities of Entheses in Patients with Psoriasis and Psoriatic Arthritis Using Noninvasive In Vivo Molecular Imaging: Results From a Cross-sectional Exploratory Study

OBJECTIVE

We assessed and compared molecular tissue changes at the entheses in patients with psoriasis (PsO) and psoriatic arthritis (PsA) and in healthy controls (HCs) in vivo using multispectral optoacoustic tomography (MSOT) and described their relationship with clinical and ultrasound findings of enthesitis.

METHODS

A cross-sectional study (MSOT and Arthrosonography in PsA) in biologic disease-modifying antirheumatic drug-naïve patients with PsA and PsO and HCs was performed. Participants underwent clinical, ultrasonographic, and MSOT examination of six entheses (lateral humeral epicondyle, distal patellar tendon attachment, and Achilles tendon attachment). MSOT-measured hemoglobin (Hb), oxygen saturation (SO2), collagen, and lipid levels were quantified, and mean differences between groups were calculated using linear mixed effects models. MSOT-measured analytes were compared between entheses with and without clinical and ultrasound anomalies.

RESULTS

Ninety participants were included (30 PsO, 30 PsA, and 30 HCs), 540 entheses were clinically assessed, and 540 ultrasound and 830 MSOT scans were obtained. Patients with PsA and PsO showed increased oxygenated Hb (PsA: P = 0.003; PsO: P = 0.054) and SO2 (PsA: P < 0.001; PsO: P = 0.001) levels and decreased collagen signals (PsA: P < 0.001; PsO: P < 0.001) compared with HCs, with more pronounced changes in PsA. Significantly lower collagen levels (P = 0.01) and increased lipids (P = 0.03) were recorded in tender entheses compared with nontender ones. Erosions and enthesophytes on ultrasound were associated with significant differences in SO2 (P = 0.014) and lipid signals (P = 0.020), respectively.

CONCLUSION

Patients with PsA and PsO exhibit an analogous metabolic pattern at the entheses that is exacerbated in the presence of inflammation. These findings support the notion of a psoriatic disease spectrum characterized by common immunometabolic tissue changes.

Looking back on 51 years of the Carol Nachman Prize in Rheumatology-significance for the field of spondyloarthritis research

The city and casino of Wiesbaden, capital of the German state Hessen, have endowed the Carol Nachman Prize to promote research work in the field of rheumatology since 1972. The prize, endowed with 37,500 €, is the second highest medical award in Germany and serves to promote clinical, therapeutic, and experimental research work in the field of rheumatology. In June 2022, the 50-year anniversary was celebrated. In the symposium preceding the award ceremony, an overview was given on the significance of spondyloarthritis for the work of the awardees in the past 30 years. This overview has now been put together to inform the interested community of the work performed, including the opinion of the awardees regarding what they consider to be their most important contribution.

Swimming exercise alleviates pathological bone features in curdlan-injected SKG mice by inducing irisin expression

This study assessed the therapeutic potential of swimming exercise in the curdlan-injected SKG mouse model and investigated the modulatory effects of irisin on inflammation. Curdlan-injected SKG were randomly assigned to either a home-cage group or a swimming group for 6 weeks. Changes in clinical arthritis scores and ankle thickness were measured weekly. Post-swimming program, mice were anesthetized for collection of vastus lateralis muscle and blood, which was followed by histological analysis, micro-CT imaging of the ankle joints, and the measurement of pro-inflammatory cytokines and irisin levels. Additionally, curdlan-injected SKG mice were intravenously injected with recombinant irisin protein and observed. Finally, serum levels of irisin in healthy control and ankylosing spondylitis (AS) patient groups were measured by ELISA. The swimming group of curdlan-injected SKG mice exhibited significant improvements in arthritis and enthesitis compared to the home-cage group. In particular, micro-CT and histological analyses revealed a notable reduction in pathological bone features in the swimming group compared to the home-cage group. Muscle endurance was also enhanced in the swimming group compared to the home-cage group, as determined by the wire-hanging test. Intriguingly, irisin levels not only were statistically increased in the swimming group but, also, TNF-α, IL-1β, and IL-6 levels were decreased. Additionally, injection of irisin protein slightly attenuated both arthritis and enthesitis in curdlan-injected SKG mice. Meanwhile, irisin serum levels were declined in AS patients. Overall, we found that swimming exercise attenuated pathological bone features in an AS animal model, potentially mediated by increased irisin serum levels with associated anti-inflammatory effects.

Dysregulated Non-Coding RNA Expression in T Cells from Patients with Ankylosing Spondylitis Contributes to Its Immunopathogenesis

Ankylosing spondylitis (AS) is a chronic inflammatory disorder characterized by inflammatory back pain and bony fusion of vertebral joints. Genetic associations and environmental factors have been proposed to explain the immunopathogenesis of AS. In the past few years, there have been major advances in understanding T cell dysfunction in AS. Clinically, targeting interleukin-17A, a major cytokine secreted by T helper 17 cells, has been approved for treating patients with active AS. Non-coding RNAs (ncRNAs) are RNA transcripts that do not translate into proteins. The ncRNAs regulate both innate and adaptive immunity and participate in the pathogenesis of autoimmune diseases, including AS. The main purpose of this article is to review the up-to-date studies investigating the aberrant expression of ncRNAs in T cells from patients with AS and to summarize their roles in its pathogenesis. After searching PubMed for studies published between January 2013 and June 2024, nine studies investigating the expression of ncRNAs in AS T cells were included. We found that aberrantly expressed ncRNAs in AS T cells could cause abnormal cytokine release, cell signaling abnormalities, and dysregulated cell proliferation and death, which contribute to the immunopathogenesis of AS. We discussed some limitations of these studies and suggested several research fields for further investigation.

50 years of spondyloarthritis: a look back and a look ahead

PURPOSE OF REVIEW

It is now 50 years since the concept of spondyloarthritis was introduced by Moll, Wright and co-authors from Leeds, UK. This review will review the original concept and mark significant milestones over the last 50 years while looking ahead to developments in the future.

RECENT FINDINGS

While the diseases included under this rubric in the original description may have changed the core conditions remain and are still characterized by axial inflammation as a common feature. Imaging, animal models, genetics and immunology have contributed to our knowledge of the pathogenesis and classification of these diseases and have led to the development of more effective treatments.

SUMMARY

Future developments, facilitated by large research consortia, will help build on our current knowledge and will help clarify disease heterogeneity and provide insights into new therapeutic pathways.

Sacroiliac radiographic progression over 10 years in axSpA: data from the DESIR inception cohort

OBJECTIVES

To evaluate sacroiliac radiographic progression over a 10-year follow-up and determine the baseline factors associated with such progression in patients with recent-onset axial spondyloarthritis (axSpA, <3 years).

METHODS

This analysis was performed in the DESIR cohort (NCT01648907). The radiographic status of the patients (radiographic axSpA (r-axSpA) vs non-radiographic axSpA (nr-axSpA)) was based on the modified New York (mNY) criteria. Information on mNY criteria on the pelvic radiographs was obtained in four reading waves over a 10-year period. Images were blinded and centrally read by 3 trained readers. The % of mNY net progressors (ie, number of 'progressors' minus number of 'regressors' divided by the total number of patients) was assessed in completers (ie, pelvic radiographs at baseline and 10 years). The yearly likelihood of mNY+ was estimated using an integrated analysis (ie, including all patients with at least one available mNY score ('intention-to-follow' population) using a generalised estimating equations model and time-varying tumour necrosis factor (TNF) use as a confounder. Baseline predictors of mNY+ during 10 years were evaluated.

RESULTS

Completers included 294 patients, while intention-to-follow included 659 participants. In the completers, the net % progression (from nr-axSpA to r-axSpA) was 5.8%. In the intention-to-follow population, the probability of being mNY+ was estimated to increase 0.87% (95% CI 0.56 to 1.19) per year (ie, 8.7% after 10 years) while when introducing TNF inhibitors (TNFi) as a time-varying covariate, the probability was 0.45% (95% CI 0.09 to 0.81) (ie, 4.5% after 10 years). Baseline bone marrow oedema (BME) on MRI of the sacroiliac joints (SIJ) was associated with being mNY+ over time OR 6.2 (95% CI 5.3 to 7.2) and OR 3.1 (95% CI 2.4 to 3.9) in HLA-B27+ and HLA-B27-, respectively). Male sex, symptom duration >1.5 years, Axial Spondyloarthritis Disease Activity Score ≥2.1 and smoking (only in HLA-B27 positives) were also associated with being mNY+ over 10 years. BME was not found to be a mediator of the HLA-B27 effect on mNY+ at 10 years.

CONCLUSIONS

The yearly likelihood of switching from nr-axSpA to r-axSpA in patients after 10 years of follow-up was low, and even lower when considering TNFi use.

New Bone Formation in Axial Spondyloarthritis: A Review

Background

Axial spondyloarthritis (axSpA) is a chronic inflammatory disease primarily affecting the sacroiliac joints (SIJs) and the spine. Imaging plays a crucial role in the diagnosis of axSpA, with magnetic resonance imaging (MRI) and radiography being the primary modalities used in clinical practice. New bone formation occurs in both the spine (non-bridging and bridging syndesmophytes, transdiscal ankylosis, and ankylosis of small joints and posterior elements) and the SIJs (backfill and ankylosis). New bone formation indicates advanced axSpA.

Method

This review explores the role of imaging in the diagnosis and monitoring of axSpA, focusing on the significance of new bone formation, and provides an overview of the characteristic imaging findings of new bone formation in axSpA in each imaging modality.

Conclusion

Imaging methods, such as X-ray, MRI, and CT, have different diagnostic accuracies for detecting structural lesions and new bone formation. Each modality has its strengths and weaknesses, and the choice depends on the specific clinical context. Imaging is crucial for the diagnosis and monitoring of axSpA, particularly for the detection of new bone formation. Different imaging techniques provide valuable information about disease progression and treatment response. Understanding the significance of new bone formation and its detection using imaging modalities is essential for the accurate diagnosis and effective management of patients with axSpA.

Key Points

Citation Format

Sequence of Events in the Pathogenesis of Axial Spondyloarthritis: A Current Review-2023 SPARTAN Meeting Proceedings

PURPOSE OF REVIEW

Over the past two decades, significant progress has been made to untangle the etiology of inflammation and new bone formation (NBF) associated with axial spondyloarthritis (axSpA). However, exact mechanisms as to how the disease initiates and develops remain elusive.

RECENT FINDINGS

Type 3 immunity, centered around the IL-23/IL-17 axis, has been recognized as a key player in the pathogenesis of axSpA. Multiple hypotheses associated with HLA-B*27 have been proposed to account for disease onset and progression of axSpA, potentially by driving downstream T cell responses. However, HLA-B*27 alone is not sufficient to fully explain the development of axSpA. Genome-wide association studies (GWAS) identified several genes that are potentially relevant to disease pathogenesis leading to a better understanding of the immune activation seen in axSpA. Furthermore, gut microbiome studies suggest an altered microbiome in axSpA, and animal studies suggest a pathogenic role for immune cells migrating from the gut to the joint. Recent studies focusing on the pathogenesis of new bone formation (NBF) have highlighted the importance of endochondral ossification, mechanical stress, pre-existing inflammation, and activated anabolic signaling pathways during the development of NBF. Despite the complex etiology of axSpA, recent studies have shed light on pivotal pieces that could lead to a better understanding of the pathogenic events in axSpA.

Association of anatomical variants of the sacroiliac joint with bone marrow edema in patients with axial spondyloarthritis

OBJECTIVE

To determine the prevalence of sacroiliac joint variants in patients with axial spondyloarthritis (axSpA) using MRI-based synthetic CT images and to evaluate their relationships with the presence of bone marrow edema, as this may potentially complicate diagnosing active sacroiliitis on MRI in patients with suspected axSpA.

METHODS

172 patients were retrospectively included. All patients underwent MRI because of clinical suspicion of sacroiliitis. The diagnosis of axSpA was made by a tertiary hospital rheumatologist. Two readers independently determined the presence of bone marrow edema and the presence of one or more of the nine known sacroiliac joint (SIJ) variants.

RESULTS

SIJ variants were common in axSpA patients (82.9%) and the non-SpA group (85.4%); there were no significant differences in prevalence. Bone marrow edema was frequently found in axSpA (86.8%) and non-SpA patients (34%). AxSpA patients with SIJ variants (except for accessory joint) demonstrated 4 to 10 times higher odds for bone marrow edema, however not statistically significant. The more variants were present in this group, the higher the chance of bone marrow edema. However, some multicollinearity cannot be excluded, since bone marrow edema is very frequent in the axSpA group by definition.

CONCLUSION

SIJ variants are common in axSpA and non-SpA patients. SIJ variants were associated with higher prevalence of bone marrow edema in axSpA patients, potentially due to altered biomechanics, except for accessory joint which may act as a stabilizer.

Enthesopathies - Mechanical, inflammatory or both?

Entheses have the challenging task of transferring biomechanical forces between tendon and bone, two tissues that differ greatly in composition and mechanical properties. Consequently, entheses are adapted to withstand these forces through continuous repair mechanisms. Locally specialized cells (mechanosensitive tenocytes) are crucial in the repair, physiologically triggering biochemical processes to maintain hemostasis. When repetitive forces cause "material fatigue," or trauma exceeds the entheses' repair capacity, structural changes occur, and patients become symptomatic. Clinical assessment of enthesopathies mainly depends on subjective reports by the patient and lacks specificity, especially in patients with central sensitization syndromes. Ultrasonography has been increasingly used to improve the diagnosis of enthesopathies. In this article, the literature on how biomechanical forces lead to entheseal inflammation, including factors contributing to differentiation into a "clinical enthesitis" state and the value of ultrasound to diagnose enthesopathies will be reviewed, as well as providing clues to overcome the pitfalls of imaging.

Patients with ankylosing spondylitis present a distinct CD8 T cell subset with osteogenic and cytotoxic potential

OBJECTIVES

Ankylosing spondylitis (AS) is a chronic inflammatory rheumatic disease affecting mainly the axial skeleton. Peripheral involvement (arthritis, enthesitis and dactylitis) and extra-musculoskeletal manifestations, including uveitis, psoriasis and bowel inflammation, occur in a relevant proportion of patients. AS is responsible for chronic and severe back pain caused by local inflammation that can lead to osteoproliferation and ultimately spinal fusion. The association of AS with the human leucocyte antigen-B27 gene, together with elevated levels of chemokines, CCL17 and CCL22, in the sera of patients with AS, led us to study the role of CCR4+ T cells in the disease pathogenesis.

METHODS

CD8+CCR4+ T cells isolated from the blood of patients with AS (n=76) or healthy donors were analysed by multiparameter flow cytometry, and gene expression was evaluated by RNA sequencing. Patients with AS were stratified according to the therapeutic regimen and current disease score.

RESULTS

CD8+CCR4+ T cells display a distinct effector phenotype and upregulate the inflammatory chemokine receptors CCR1, CCR5, CX3CR1 and L-selectin CD62L, indicating an altered migration ability. CD8+CCR4+ T cells expressing CX3CR1 present an enhanced cytotoxic profile, expressing both perforin and granzyme B. RNA-sequencing pathway analysis revealed that CD8+CCR4+ T cells from patients with active disease significantly upregulate genes promoting osteogenesis, a core process in AS pathogenesis.

CONCLUSIONS

Our results shed light on a new molecular mechanism by which T cells may selectively migrate to inflammatory loci, promote new bone formation and contribute to the pathological ossification process observed in AS.

An update of murine models and their methodologies in immune-mediated joint damage and pain research

Murine models have played an indispensable role in the understanding of rheumatic and musculoskeletal disorders (RMD), elucidating the genetic, endocrine and biomechanical pathways involved in joint pathology and associated pain. To date, the available models in RMD can be classified as induced or spontaneous, both incorporating transgenic alternatives that improve specific insights. It is worth noting that the selection of the most appropriate model together with the evaluation of their specific characteristics and technical capabilities are crucial when designing the experiments. Furthermore, it is also imperative to consistently adhere to the ethical standards concerning animal experimentation. Recognizing the inherent limitation that any model can entirely encapsulates the complexity of the pathophysiology of these conditions, the aim of this review is to provide an updated overview on the methodology of current murine models in major arthropathies and their immune-mediated pathways, addressing to basic, translational and pharmacological research in joint damage and pain.

The Role of Early Treatment in the Management of Axial Spondyloarthritis: Challenges and Opportunities

Axial spondyloarthritis (axSpA) is a chronic, inflammatory rheumatic disease that primarily affects the axial skeleton, often inflicting severe pain, diminished mobility, and a compromised quality of life. The advent of Assessment of SpondyloArthritis international Society (ASAS) classification criteria for spondyloarthritis (SpA) have enabled the classification of patients with axSpA in the non-radiographic stage but poorly perform if mistakenly used for diagnostic purposes. Despite notable progress in early diagnosis facilitated by referral strategies and extensive magnetic resonance imaging (MRI) utilization, diagnostic delays persist as a concerning issue. This underscores the urgency to narrow the diagnostic gap and highlights the critical role of early diagnosis in mitigating the long-term structural damage associated with this condition. Research into the impact of non-steroidal anti-inflammatory drugs (NSAIDs) and biologic disease-modifying antirheumatic drugs (bDMARDs) on inflammatory symptoms and radiographic progression has been extensive. A compelling body of evidence suggests that early intervention leads to superior disease outcomes. However, most of these studies have centered on patients with established diseases rather than those in the early stages. Consequently, findings from studies on early pharmacological intervention remain inconclusive, and the potential for modifying the disease trajectory is still debatable. Without precise data from clinical trials, insights from basic science regarding the pathogenic mechanisms might point toward potential targets that warrant early intervention in the disease process. This review underscores the urgency of early diagnosis and intervention in axSpA, highlighting ongoing research gaps and the need for further exploration to improve patient outcomes.

The association between sonographic enthesitis with sonographic synovitis and tenosynovitis in psoriatic arthritis patients

OBJECTIVES

To examine the association between sonographic enthesitis with sonographic synovitis and tenosynovitis in PsA patients, and the association between sonographic enthesitis and clinical characteristics.

METHODS

Consecutive PsA patients that fulfilled the ClASsification criteria for Psoriatic ARthritis (CASPAR) were prospectively recruited. Each patient was evaluated by comprehensive clinical and sonographic assessment (greyscale and Doppler), the latter including 52 joints, 40 tendons and 14 entheses [according to MAdrid Sonography Enthesitis Index (MASEI) plus lateral epicondyles] performed by an experienced sonographer blinded to the clinical data. The US enthesitis score was further categorized to inflammatory (hypoechogenicity, thickening, bursitis and Doppler) and structural (enthesophytes/calcifications and erosions) subcategories. Multivariate linear regression models assessed the association between enthesitis and the selected variables.

RESULTS

A total of 158 PsA patients [mean (s.d.) age 52.3 (13) years, 88 (55.7%) females] were analysed. Multivariate linear regression analyses showed a significant association between sonographic enthesitis and sonographic synovitis (β = 0.18, P = 0.008) and between sonographic enthesitis and sonographic tenosynovitis (β = 0.06, P = 0.02). These associations were derived from the enthesitis inflammatory subcategory of the MASEI (P < 0.05). Associations between enthesitis and synovitis were also demonstrated on the level of the elbow, knee and ankle joints (P < 0.05). In addition, sonographic enthesitis was significantly associated with older age, male sex, swollen joint count, CRP level and physical occupation.

CONCLUSIONS

Sonographic enthesitis is associated with sonographic synovitis and tenosynovitis. The severity of sonographic enthesitis may represent a marker for inflammatory activity in other musculoskeletal domains.

Disease characteristics, pathogenesis, and treatment controversies of axial psoriatic arthritis

Axial psoriatic arthritis (axPsA) has considerable overlap with axial spondyloarthritis (axSpA) but has some unique features that sometimes preclude classification into axSpA. It has some clinical and radiographic differences compared to axSpA. Imaging typically shows asymmetric syndesmophytes, mainly in the cervical spine, with less frequent sacroiliitis. It more commonly presents later in life and is associated with less severe inflammatory back pain than axSpA. The interleukin (IL) IL-23/IL-17 axis is central to the pathogenesis of both diseases. However, the response to therapies targeting these cytokines has been different. IL-23 inhibitors are ineffective in axSpA but may be effective in psoriatic arthritis (PsA). Recent post hoc analyses of clinical trial data with IL-23 inhibitors in PsA have raised the possibility of their efficacy in axPsA and need evaluation in future clinical trials. Moreover, there is a need for classification criteria for axPsA and better tools to assess therapeutic response.

Looking through the window of opportunity in axial spondyloarthritis?

Axial spondyloarthritis (axSpA) is a chronic inflammatory disease that affects the spine and sacroiliac joints, that can lead to irreversible structural damage. Early detection and timely intervention are crucial for preventing long-term structural damage, improving quality of life, and reducing the burden of the disease. The concept of a window of opportunity suggests that an early intervention in the reversible stage of the disease can lead to improved long-term outcomes. However, it is unclear whether this concept applies in axSpA. Recent advances in axSpA management, including the use of diagnostic techniques such as magnetic resonance imaging as well as the use of advanced therapies, have shown promise in improving outcomes. However, studies investigating the potential window of opportunity in axSpA by assessing the impact of an early treatment on clinical outcomes have yielded inconclusive results. One of the reasons behind this is the lack of a standardized definition of early axSpA. The Assessment of Spondyloarthritis International Society (ASAS)-SPEAR (SPondyloarthritis EARly) project has set the ground for it by working on a consensus definition of early axSpA. Randomized controlled trials specifically focused on the comparison between treating axSpA in the early and late stages of the disease and using the standardised definition of early axSpA are essential to understand better the potential benefits of an early treatment on clinical outcomes. Additionally, it would be relevant to assess the long-term outcomes of early axSpA treatment, especially regarding structural damage, to better grasp the concept of the window of opportunity in axSpA.

Tolerability of low to moderate biomechanical stress during leisure sport activity in patients with psoriasis and psoriatic arthritis

OBJECTIVES

To assess the impact of low to moderate biomechanical stress on entheses in patients with psoriasis and psoriatic arthritis (PsA).

METHODS

We conducted a prospective interventional study on a cohort of psoriasis and PsA patients who underwent a 60 min badminton training session. Pain assessment by Visual Analogue Scale (VAS), physical examination of 29 entheses (SPARCC, LEI, MASES) and bilateral ultrasound at the lateral humeral epicondyle, inferior patellar pole and Achilles tendon were performed before and after training. Ultrasound changes were assessed using the OMERACT scoring system. A follow-up assessment of pain and adverse events was performed at 1 week.

RESULTS

Sixteen patients were included (n=7 PsA; n=9 psoriasis) and 196 entheseal ultrasound scans were acquired. At baseline, median VAS pain (IQR) was 0.5 cm (0-2.3) and the total number of tender entheses was 12/464. Mean (min; max) Disease Activity Index for Psoriatic Arthritis was 6.1 (0.8; 19) and 5/7 PsA patients had an Minimal Disease Activity status. After training, no significant change in VAS pain (0.0 cm (0.0-2.0)) nor in tender entheses (13/464) emerged. Four patients (n=2 PsA, n=2 psoriasis) developed a grade-1 power Doppler-signal at six entheses, which, however, remained non-tender. At 1 week, median VAS pain remained stable (0.0 cm (0.0-3.0); p>0.05) and only one participant with active PsA at baseline reported increased arthralgias in three joints.

CONCLUSIONS

Low to moderate physical strain, as in the context of leisure sport activity, seems well tolerated in psoriatic patients without increases in tenderness, pain and ultrasound-proven inflammation. Evidence-based recommendations for physical activity in PsA are direly needed and larger controlled studies should be conducted to define safe exercise thresholds.

Development of Spinal Enthesopathies in Adults With X-linked Hypophosphatemia

CONTEXT

Musculoskeletal complications are the main manifestations in adults with X-linked hypophosphatemia (XLH). Enthesopathy significantly impairs quality of life.

OBJECTIVE

To identify the risk factors associated with the development and progression of spinal enthesopathies in adults with XLH.

DESIGN AND SETTING

We conducted a retrospective study in the French Reference Center for Rare Diseases of the Calcium and Phosphate Metabolism.

PATIENTS

Adults XLH patients with 2 EOS® imaging performed at least 2 years apart at the same center between June 2011 and March 2022. The progression of enthesopathies was defined as a new enthesopathy at least 1 intervertebral level in patients with or without presence of enthesopathy at baseline.

MAIN OUTCOME MEASURES

Demographic, treatment, PHEX mutation with the progression of enthesopathies.

RESULTS

Fifty-one patients (66.7% of women, mean age 42.1 ± 13.4 years) underwent 2 EOS imaging with an average interval of 5.7 (± 2.31) years.Progression of spinal enthesopathies was observed in 27 (52.9%) patients. In univariate analysis, patients with a progression of spinal enthesopathies were significantly older (P < .0005), were significantly older at treatment initiation (P = .02), presented with dental complications (P = .03), received less frequently treatment during childhood with phosphate and/or vitamin D analogs (P = .06), and presented more frequently with hip osteoarthritis (P = .002) at baseline. In multivariate analysis, none of these factors was associated with a progression of spinal enthesopathies.

CONCLUSION

This study confirms the high proportion of patients with a progression of spinal enthesopathies. Age seems to be the main factor associated with progression.

Biomechanics in the onset and severity of spondyloarthritis: a force to be reckoned with

Increasing evidence suggests that there is a pivotal role for physical force (mechanotransduction) in the initiation and/or the perpetuation of spondyloarthritis; the review contained herein examines that evidence. Furthermore, we know that damage and inflammation can limit spinal mobility, but is there a cycle created by altered spinal mobility leading to additional damage and inflammation?Over the past several years, mechanotransduction, the mechanism by which mechanical perturbation influences gene expression and cellular behaviour, has recently gained popularity because of emerging data from both animal models and human studies of the pathogenesis of ankylosing spondylitis (AS). In this review, we provide evidence towards an appreciation of the unsolved paradigm of how biomechanical forces may play a role in the initiation and propagation of AS.

Body Mass Index and the Risk of Rheumatic Disease: Linear and Nonlinear Mendelian Randomization Analyses

OBJECTIVE

Although the association between obesity and risk of rheumatic disease is well established, the precise causal relation has not been conclusively proven. Here, we estimate the causal effect of body mass index (BMI) on the risk of developing 5 different rheumatic diseases.

METHODS

Linear and nonlinear mendelian randomization (MR) were used to estimate the effect of BMI on risk of rheumatic disease, and sex-specific effects were identified. Analyses were performed in 361,952 participants from the UK Biobank cohort for 5 rheumatic diseases: rheumatoid arthritis (n = 8,381 cases), osteoarthritis (n = 87,430), psoriatic arthropathy (n = 933), gout (n = 13,638), and inflammatory spondylitis (n = 4,328).

RESULTS

Using linear MR, we found that 1 SD increase in BMI increases the incidence rate for rheumatoid arthritis (incidence rate ratio [IRR] 1.52 [95% confidence interval (95% CI) 1.36-1.69]), osteoarthritis (IRR 1.49 [95% CI 1.43-1.55]), psoriatic arthropathy (IRR 1.80 [95% CI 1.31-2.48]), gout (IRR 1.73 [95% CI 1.56-1.92]), and inflammatory spondylitis (IRR 1.34 [95% CI 1.14-1.57]) in all individuals. BMI was found to be a stronger risk factor in women compared to men for psoriatic arthropathy (P for sex interaction = 3.3 × 10-4 ) and gout (P for sex interaction = 4.3 × 10-3 ), and the effect on osteoarthritis was stronger in premenopausal compared to postmenopausal women (P = 1.8 × 10-3 ). Nonlinear effects of BMI were identified for osteoarthritis and gout in men, and for gout in women. The nonlinearity for gout was also more extreme in men compared to women (P = 0.03).

CONCLUSION

Higher BMI causes an increased risk for rheumatic disease, an effect that is more pronounced in women for both gout and psoriatic arthropathy. The novel sex- and BMI-specific causal effects identified here provide further insight into rheumatic disease etiology and mark an important step toward personalized medicine.

Sterile triggers drive joint inflammation in TNF- and IL-1β-dependent mouse arthritis models

Arthritis is the most common extra-intestinal complication in inflammatory bowel disease (IBD). Conversely, arthritis patients are at risk for developing IBD and often display subclinical gut inflammation. These observations suggest a shared disease etiology, commonly termed "the gut-joint-axis." The clinical association between gut and joint inflammation is further supported by the success of common therapeutic strategies and microbiota dysbiosis in both conditions. Most data, however, support a correlative relationship between gut and joint inflammation, while causative evidence is lacking. Using two independent transgenic mouse arthritis models, either TNF- or IL-1β dependent, we demonstrate that arthritis develops independently of the microbiota and intestinal inflammation, since both lines develop full-blown articular inflammation under germ-free conditions. In contrast, TNF-driven gut inflammation is fully rescued in germ-free conditions, indicating that the microbiota is driving TNF-induced gut inflammation. Together, our study demonstrates that although common inflammatory pathways may drive both gut and joint inflammation, the molecular triggers initiating such pathways are distinct in these tissues.

Bone Involvement in Rheumatoid Arthritis and Spondyloartritis: An Updated Review

Several rheumatologic diseases are primarily distinguished by their involvement of bone tissue, which not only serves as a mere target of the condition but often plays a pivotal role in its pathogenesis. This scenario is particularly prominent in chronic inflammatory arthritis such as rheumatoid arthritis (RA) and spondyloarthritis (SpA). Given the immunological and systemic nature of these diseases, in this review, we report an overview of the pathogenic mechanisms underlying specific bone involvement, focusing on the complex interactions that occur between bone tissue's own cells and the molecular and cellular actors of the immune system, a recent and fascinating field of interest defined as osteoimmunology. Specifically, we comprehensively elaborate on the distinct pathogenic mechanisms of bone erosion seen in both rheumatoid arthritis and spondyloarthritis, as well as the characteristic process of aberrant bone formation observed in spondyloarthritis. Lastly, chronic inflammatory arthritis leads to systemic bone involvement, resulting in systemic bone loss and consequent osteoporosis, along with increased skeletal fragility.

Immune-mediated inflammatory diseases: Common and different pathogenic and clinical features

The term "immune-mediated inflammatory diseases (IMIDs)" refers to several inflammatory pathologies of multifactorial etiology and involving either simultaneously or sequentially more organs. IMIDs share some common pathogenic mechanisms, which account for some similarities in the clinical course and the impact that these diseases may have on other organs and systems of the body. However, there are some differences in the IMID-associated pathological process, including the synthesis and function of multiple inflammatory cytokines, which are supposed to perpetuate the tissue-damaging inflammation. This justifies the different indications and responsiveness to corticosteroids, immunosuppressors, small molecules, and biologics. Many individuals with IMIDs are, however, intolerant, or unresponsive to the current drugs, thus suggesting the necessity of novel therapeutic approaches, such as the combination of compounds that either inhibit more immuno-inflammatory networks selectively or simultaneously suppress inflammatory signals and activate counter-regulatory pathways. In this article, we highlight the most relevant features of IMIDs and discuss how clinicians can combat the detrimental immune response in such disorders.

The Role of Sclerostin in Rheumatic Diseases: A Review

Systemic connective tissue disorders constitute a heterogenous group of autoimmune diseases with the potential to affect a range of organs. Rheumatoid arthritis (RA) is a chronic, progressive, autoimmune inflammatory disease affecting the joints. Systemic lupus erythematosus (SLE) may manifest with multiple system involvement as a result of inflammatory response to autoantibodies. Spondyloarthropathies (SpAs) such as ankylosing spondylitis (AS) or psoriatic arthritis (PsA) are diseases characterised by the inflammation of spinal joints, paraspinal tissues, peripheral joints and enthesitis as well as inflammatory changes in many other systems and organs. Physiologically, sclerostin helps to maintain balance in bone tissue metabolism through the Wnt/β-catenin pathway, which represents a major intracellular signalling pathway. This review article aims to present the current knowledge on the role of sclerostin in the Wnt/β-catenin pathway and its correlation with clinical data from RA, SLE, AS and PsA patients.

Changes of inflammation in patients with psoriatic arthritis after high intensity interval training assessed by ultrasound and MRI, a randomized controlled trial

BACKGROUND

In psoriatic arthritis (PsA) there is a theoretical risk of increased disease activity related to strenuous physical activity, including exercise. We evaluated the effect of high intensity interval training (HIIT) on objective measures of inflammation in PsA assessed by ultrasound (US) of peripheral joints and entheses, and by bone marrow edema (BME) on MRI of the sacroiliac joints (SIJ) and spine.

METHODS

We randomly assigned 67 PsA patients to an intervention group that performed structured HIIT for 11 weeks, or to a control group instructed not to change their physical exercise habits. Outcome measures included US evaluation of the total cohort and MRI in a subgroup of 41; both assessed at 3 months. We calculated the proportions with an increased US B-mode and power-doppler (PD) signal of joints and entheses and Spondyloarthritis-Research-Consortium-of-Canada (SPARCC)-BME score of the SIJ and spine for both groups.

RESULTS

Proportions with an increased US B-mode score of the joints were 32% and 28% in HIIT and control groups, respectively. Corresponding proportions of PD scores of the joints were 7% and 10% and PD scores of entheses were 32% and 31%. The proportions with increased MRI BME of the SIJ were 6% in the HIIT group and 10% in the control group. Corresponding proportions were 6% and 5% for the MRI BME of the spine.

CONCLUSION

In PsA patients with a low to moderate disease activity, there was no clear evidence of objectively measured increased inflammation after HIIT, as evaluated by US and MRI.

TRIAL REGISTRATION

ClinicalTrials.gov NCT02995460 (16/12/2016).

The Use of Superb Microvascular Imaging in Evaluating Rheumatic Diseases: A Systematic Review

Background and Objectives: Superb microvascular imaging is an advanced Doppler algorithm that seems to be useful in detecting low-velocity blood flow without using a contrast agent. Increasing evidence suggests that SMI is a more sensitive tool than conventional Doppler techniques for evaluating rheumatic diseases, especially inflammatory arthritis. We aimed to assess the use of SMI in evaluating joints and extraarticular structures. Materials and Methods: Two reviewers independently reviewed the literature to provide a global overview of the possibilities of SMI in rheumatology. Original English-language articles published between February 2014 and November 2022 were identified through database (PubMed, Medline, Ebsco, the Cochrane Library, and ScienceDirect) searching, and analysed to summarise existing evidence according to PRISMA methodology. Inclusion criteria covered original research articles reporting applications of SMI on rheumatic diseases and musculoskeletal disorders secondary to rheumatic conditions. Qualitative data synthesis was performed. Results: A total of 18 articles were included. No systematic reviews fulfilled our inclusion criteria. Most studies focused on characterising the synovial vascularity of rheumatoid arthritis. There have been several attempts to demonstrate SMI's value for evaluating extra-articular soft tissues (fat pads or salivary glands) and large-diameter vessels. The quantitative importance of SMI vascular indices could become a useful non-invasive diagnostic marker. Studies on therapeutic applications are still scarce, and the majority of studies have gaps in reporting the methodology (ultrasound performance technique and settings) of the research. Conclusions: SMI has proved to be useful in characterising low-flow vascularity, and growing evidence indicates that SMI is a non-invasive and lower-cost tool for prognostic assessment, especially in inflammatory arthritis. Preliminary findings also suggest potential interest in evaluating the effect of treatment.

Association of childhood infections and perinatal factors with ankylosing spondylitis: a Swedish nationwide case-control and sibling study

OBJECTIVES

To identify perinatal and early-life risk factors for ankylosing spondylitis (AS), controlling for family-shared confounding with a sibling comparison design.

METHODS

In this nationwide, register-based case-control study, we identified 5612 AS cases from the Swedish National Patient Register, and matched them with 22 042 individuals without inflammatory arthritis from the general population. Conditional logistic regression was used to estimate odds ratios (ORs) and 95% confidence intervals (CIs) of AS in relation to childhood infections and a broad range of perinatal factors including fetal growth. Significant associations were further tested in a sibling comparison analysis, including 3965 patients with AS and their 6070 siblings without a diagnosis of spondyloarthritis.

RESULTS

We found no statistically significant associations between any studied fetal growth-related factor or other perinatal factors and the risk of developing AS. In contrast, having older siblings (adjusted OR 1.12; 95% CI 1.04 to 1.22 for one vs no older sibling) and history of a childhood tonsillectomy (adjusted OR 1.30; 95% CI 1.13 to 1.49) were associated with AS in the case-control analysis, results that also held in the sibling comparison. Serious childhood infection and multiple birth were significantly associated with AS in the case-control sample, but estimates were attenuated in the sibling comparison.

CONCLUSIONS

Having older siblings and a history of tonsillectomy in childhood were independently associated with development of AS, even after adjustment for family-shared factors in a sibling comparison analysis. This strengthens the hypothesis that childhood infections play a role in the aetiology of AS.

Advances in pharmacotherapies for axial spondyloarthritis

INTRODUCTION

Axial spondyloarthritis (axSpA) refers to an inflammatory rheumatic disease that mainly affects the axial skeleton and leads to progressive radiographic changes of the sacroiliac joints and spine. axSpA is currently subdivided into the radiographic (r-axSpA) and non-radiographic (nr-axSpA) form. Both forms are associated with musculoskeletal pain, restriction of spinal mobility, specific extra-musculoskeletal manifestations, and overall, altered quality of life. The therapeutic management of axSpA is currently well standardized.

AREAS COVERED

We reviewed available literature (by using PubMed search) on non-pharmacological and pharmacological treatment options that may be used in axSpA, including r-axSpA and nr-axSpA, as well as the role of non-steroidal anti-inflammatory drugs (NSAIDs), biological agents including TNFalpha (TNFi) and IL-17 (IL-17i) inhibitors. New treatment options such as Janus kinase inhibitors are also reviewed.

EXPERT OPINION

NSAIDs remain the mainstay of initial therapy, and subsequently, biological agents (TNFi and IL-17i) may be envisaged. Four TNFi are licensed for the treatment of both r-axSpA and nr-axSpA, while IL-17i are approved in each indication. The choice between a TNFi and an IL-17i is mainly guided by the presence of extra-articular manifestations. JAKi were more recently introduced for the treatment of r-axSpA, but their use is restricted to specific patients with a safe cardiovascular profile.

Pathophysiology and immunolgical basis of axial spondyloarthritis

Over the recent years the wider availability and application of state-of-the-art immunological technologies greatly advanced the insight into the mechanisms that play an important role in axial spondyloarthritis (axSpA) pathophysiology. This increased understanding has facilitated the development of novel treatments that target disease relevant pathways, hereby improving outcome for axSpA patients. In axSpA pathophysiology genetic and environmental factors as well as immune activation by mechanical or bacterial stress resulting in a chronic inflammatory response have a central role. The TNF and IL-23/IL-17 immune pathways play a pivotal role in these disease mechanisms. This review provides an outline of the immunological basis of axSpA with a focus on key genetic risk factors and their link to activation of the pathological immune response, as well as on the role of the gut and entheses in the initiation of inflammation with subsequent new bone formation in axSpA.

The Conundrum of Psoriatic Arthritis: a Pathogenetic and Clinical Pattern at the Midpoint of Autoinflammation and Autoimmunity

Psoriatic arthritis (PsA) is a chronic inflammatory condition characterized by psoriasis, synovitis, enthesitis, spondylitis, and the possible association with other extra-articular manifestations and comorbidities. It is a multifaceted and systemic disorder sustained by complex pathogenesis, combining aspects of autoinflammation and autoimmunity. Features of PsA autoinflammation include the role of biomechanical stress in the onset and/or exacerbation of the disease; the evidence of involvement of the innate immune response mediators in the skin, peripheral blood and synovial tissue; an equal gender distribution; the clinical course which may encounter periods of prolonged remission and overlapping features with autoinflammatory syndromes. Conversely, the role of autoimmunity is evoked by the association with class I major histocompatibility complex alleles, the polyarticular pattern of the disease which sometimes resembles rheumatoid arthritis and the presence of serum autoantibodies. Genetics also provide important insights into the pathogenesis of PsA, particularly related to class I HLA being associated with psoriasis and PsA. In this review, we provide a comprehensive review of the pathogenesis, genetics and clinical features of PsA that endorse the mixed nature of a disorder at the crossroads of autoinflammation and autoimmunity.

The bone marrow side of axial spondyloarthritis

Spondyloarthritis (SpA) is characterized by the infiltration of innate and adaptive immune cells into entheses and bone marrow. Molecular, cellular and imaging evidence demonstrates the presence of bone marrow inflammation, a hallmark of SpA. In the spine and the peripheral joints, bone marrow is critically involved in the pathogenesis of SpA. Evidence suggests that bone marrow inflammation is associated with enthesitis and that there are roles for mechano-inflammation and intestinal inflammation in bone marrow involvement in SpA. Specific cell types (including mesenchymal stem cells, innate lymphoid cells and γδ T cells) and mediators (Toll-like receptors and cytokines such as TNF, IL-17A, IL-22, IL-23, GM-CSF and TGFβ) are involved in these processes. Using this evidence to demonstrate a bone marrow rather than an entheseal origin for SpA could change our understanding of the disease pathogenesis and the relevant therapeutic approach.

Spondyloarthritis with inflammatory bowel disease: the latest on biologic and targeted therapies

Spondyloarthritis (SpA) encompasses a heterogeneous group of chronic inflammatory diseases that can affect both axial and peripheral joints, tendons and entheses. Among the extra-articular manifestations, inflammatory bowel disease (IBD) is associated with considerable morbidity and effects on quality of life. In everyday clinical practice, treatment of these conditions requires a close collaboration between gastroenterologists and rheumatologists to enable early detection of joint and intestinal manifestations during follow-up and to choose the most effective therapeutic regimen, implementing precision medicine for each patient's subtype of SpA and IBD. The biggest issue in this field is the dearth of drugs that are approved for both diseases, as only TNF inhibitors are currently approved for the treatment of full-spectrum SpA-IBD. Janus tyrosine kinase inhibitors are among the most promising drugs for the treatment of peripheral and axial SpA, as well as for intestinal manifestations. Other therapies such as inhibitors of IL-23 and IL-17, phosphodiesterase 4 inhibitor, α4β7 integrin blockers and faecal microbiota transplantation seem to only be able to control some disease domains, or require further studies. Given the growing interest in the development of novel drugs to treat both conditions, it is important to understand the current state of the art and the unmet needs in the management of SpA-IBD.

Enthesitis in patients with psoriatic arthritis: A nationwide data from the Chinese Registry of Psoriatic Arthritis (CREPAR)

BACKGROUND

The clinical features of enthesitis in patients with psoriatic arthritis (PsA) have been reported in some Western countries, but data in China are very limited. This study aimed to describe the characteristics of enthesitis in Chinese patients with PsA and compared them with those in other cohorts.

METHODS

Patients with PsA enrolled in the Chinese Registry of Psoriatic Arthritis (CREPAR) (December 2018 to June 2021) were included. Data including demographics, clinical characteristics, disease activity measures, and treatment were collected at enrollment. Enthesitis was assessed by the Spondyloarthritis Research Consortium of Canada (SPARCC), Maastricht ankylosing spondylitis enthesitis score (MASES), and Leeds enthesitis index (LEI) indices. A multivariable logistic model was used to identify factors related to enthesitis. We also compared our results with those of other cohorts.

RESULTS

In total, 1074 PsA patients were included, 308 (28.7%) of whom had enthesitis. The average number of enthesitis was 3.3 ± 2.8 (range: 1.0-18.0). More than half of the patients (165, 53.6%) had one or two tender entheseal sites. Patients with enthesitis had an earlier age of onset for both psoriasis and arthritis, reported a higher proportion of PsA duration over 5 years, and had a higher percentage of axial involvement and greater disease activity. Multivariable logistic regression showed that axial involvement (odds ratio [OR] 2.21, 95% confidence interval [CI], 1.59-3.08; P <0.001), psoriasis area and severity index (PASI) (OR: 1.03, 95% CI: 1.01-1.04; P = 0.002), and disease activity score 28-C reactive protein (DAS28-CRP) (OR: 1.25, 95% CI: 1.01-1.55; P = 0.037) were associated with enthesitis. Compared with the results of other studies, Chinese patients with enthesitis had a younger age, lower body mass index (BMI), a higher rate of positive human leukocyte antigen (HLA)-B27, more frequent dactylitis, and a higher proportion of conventional synthetic disease-modifying antirheumatic drugs' (csDMARDs) use.

CONCLUSIONS

Enthesitis is a common condition among Chinese patients with PsA. It is important to evaluate entheses in both peripheral and axial sites.

Biology and therapeutic potential of mesenchymal stem cell extracellular vesicles in axial spondyloarthritis

Axial spondyloarthritis (AxSpA) is a chronic, inflammatory, autoimmune disease that predominantly affects the joints of the spine, causes chronic pain, and, in advanced stages, may result in spinal fusion. Recent developments in understanding the immunomodulatory and tissue-differentiating properties of mesenchymal stem cell (MSC) therapy have raised the possibility of applying such treatment to AxSpA. The therapeutic effectiveness of MSCs has been shown in numerous studies spanning a range of diseases. Several studies have been conducted examining acellular therapy based on MSC secretome. Extracellular vesicles (EVs) generated by MSCs have been proven to reproduce the impact of MSCs on target cells. These EVs are associated with immunological regulation, tissue remodeling, and cellular homeostasis. EVs' biological effects rely on their cargo, with microRNAs (miRNAs) integrated into EVs playing a particularly important role in gene expression regulation. In this article, we will discuss the impact of MSCs and EVs generated by MSCs on target cells and how these may be used as unique treatment strategies for AxSpA.

Piezo1-mediated mechanotransduction promotes entheseal pathological new bone formation in ankylosing spondylitis

OBJECTIVE

The aim of this study was to identify the role of Piezo1-mediated mechanotransduction in entheseal pathological new bone formation and to explore the underlying molecular mechanism.

METHODS

Spinal ligament tissues were collected from 14 patients with ankylosing spondylitis (AS) and 14 non-AS controls and bulk RNA sequencing was conducted. Collagen antibody-induced arthritis models were established to observe pathological new bone formation. Pharmacological inhibition and genetic ablation of Piezo1 was performed in animal models to identify the essential role of Piezo1. Entheseal osteo-chondral lineage cells were collected and in vitro cell culture system was established to study the role and underlying mechanism of Piezo1 in regulation of chondrogenesis, osteogenesis and its own expression.

RESULTS

Piezo1 was aberrantly upregulated in ligaments and entheseal tissues from patients with AS and animal models. Pharmaceutical and genetic inhibition of Piezo1 attenuated while activation of Piezo1 promoted pathological new bone formation. Mechanistically, activation of CaMKII (Calcium/calmodulin dependent protein kinase II) signalling was found essential for Piezo1-mediated mechanotransduction. In addition, Piezo1 was upregulated by AS-associated inflammatory cytokines.

CONCLUSION

Piezo1-mediated mechanotransduction promotes entheseal pathological new bone formation through CaMKII signalling in AS.

Site-specific assessment of spinal radiographic progression improves detection of TNF blocker-associated disease modification in axial spondyloarthritis: longitudinal observational data from the Swiss Clinical Quality Management Registry

OBJECTIVES

To analyse whether time-varying treatment with tumour necrosis factor inhibitors (TNFi) in radiographic axial spondyloarthritis (r-axSpA) has a differential impact on structural damage progression on different spinal segments (cervical versus lumbar spine).

METHODS

Patients with r-axSpA in the Swiss Clinical Quality Management cohort were included if cervical and lumbar radiographs were available at intervals of 2 years for a maximum of 10 years. Paired radiographs were scored by two calibrated readers according to the modified Stoke Ankylosing Spondylitis Spine Score (mSASSS). The relationship between TNFi use and progression in the cervical and the lumbar spine was analysed using generalised estimating equation models and adjustment for potential confounding. Radiographic progression per spinal segment was defined as an increase of ≥ 1 mSASSS unit or by the formation of ≥ 1 new syndesmophyte over 2 years.

RESULTS

Mean ± SD symptom duration was 13.8 ± 9.8 years. Mean ± SD mSASSS progression per radiographic interval was 0.41 ± 1.69 units in the cervical spine and 0.45 ± 1.45 units in the lumbar spine (p = 0.66). Prior use of TNFi significantly reduced the odds of progression in the cervical spine by 68% (OR 0.32, 95% CI 0.14-0.72), but not in the lumbar spine (OR 0.99, 95% CI 0.52-1.88). A more restricted inhibition of progression in the lumbar spine was confirmed after multiple imputation of missing covariate data (OR 0.43, 95% CI 0.24-0.77 and 0.85, 95% CI 0.51-1.41, for the cervical and lumbar spine, respectively). It was also confirmed with progression defined as formation of ≥ 1 syndesmophyte (OR 0.31, 95% CI 0.12-0.80 versus OR 0.56, 95% CI 0.26-1.24 for the cervical and lumbar spine, respectively).

CONCLUSION

Disease modification by treatment with TNFi seems to more profoundly affect the cervical spine in this r-axSpA population with longstanding disease. Site-specific analysis of spinal progression might, therefore, improve detection of disease modification in clinical trials in axSpA.

Anatomical variation of the sacroiliac joint carries an increased risk for erosion and bone marrow oedema in axial spondyloarthritis

OBJECTIVES

To assess the impact of joint shape variations on inflammatory lesions on SI joint MRIs in patients with axial spondyloarthritis (axSpA).

METHODS

A total of 1194 patients from four different prospective cohorts were evaluated, with 684 (57.3%) having sufficient imaging data for inclusion (379 axSpA, 305 controls). All images were evaluated for joint form, erosion, sclerosis, fat metaplasia and bone marrow oedema (BMO) by two independent readers. Logistic regression analyses were used to assess the association of joint form and lesions on imaging for axSpA patients and controls.

RESULTS

Atypical joint forms were common in both axSpA (43.5% [154/354]) and control patients (44.2% [134/303]); both intra-articular variants and a crescent joint shape were significantly more common in axSpA patients (18.4% vs 11.6% and 11.0% vs 5.3.%, respectively; P < 0.001). The axSpA patients with intra-articular joint form variants had 2-fold higher odds of exhibiting erosions [odds ratio (OR) 2.09 (95% CI 1.18, 3.69)] and BMO [OR 1.79 (95% CI 1.13, 2.82)]; this association was not observed in controls. Accessory joints increased the odds for sclerosis in axSpA patients [OR 2.54 (95% CI 1.10, 5.84)] and for sclerosis [OR 17.91 (95% CI 6.92, 46.37)] and BMO [OR 2.05 (95% CI 1.03, 4.07)] in controls.

CONCLUSIONS

Joint form variations are associated with the presence of inflammatory lesions on SI joint MRIs of axSpA patients. This should be taken into consideration in future research on the interplay of mechanical strain and inflammation in axSpA.

Sex Disparities of the Sacroiliac Joint: Focus on Joint Anatomy and Imaging Appearance

The sacroiliac joint (SIJ) is an anatomically complex joint which, as a functional unit with the pelvis and spine, is of decisive biomechanical importance for the human body. It is also a commonly overlooked source of lower back pain. Like the entire bony pelvis, the SIJ exhibits major sexual dimorphisms; thus, the sex-dependent evaluation of this joint is becoming increasingly important in clinical practice, both anatomically with joint shape variations and biomechanical differences as well as in terms of image appearance. The influence of the SIJ shape, which differs in women and men, is crucial for the different biomechanical joint properties. These differences are important in the development of joint diseases at the SIJ, which shows a specific difference between the sexes. This article aims to provide an overview of sex disparities of the SIJ regarding different anatomical and imaging appearances to further understand the insights into the interplay of sex differences and SIJ disease.