Use of immunohistologic and in situ hybridization techniques in the examination of sacroiliac joint biopsy specimens from patients with ankylosing spondylitis

Mechanisms of ossification of the entheses in spondyloarthritis physiopathogenic aspects and possible therapeutic implication

This review examines the molecular mechanisms driving structural damage in Spondyloarthritis (SpA), a chronic inflammatory condition characterized by new bone formation that can lead to partial or complete spinal ankylosis. We explore the complex interplay between inflammation, mechanical stress, and bone metabolism in SpA, focusing on key signaling pathways and cytokines that contribute to disease progression. The review analyzes both structural and inflammatory aspects, particularly the role of enthesis biology and the impact of mechanical factors. Additionally, we assess how current therapeutic approaches, including biologic treatments targeting specific inflammatory pathways such as tumor necrosis factor inhibitors, affect disease progression. While these treatments can reduce inflammation and manage clinical symptoms, their limited ability to completely prevent new bone formation highlights the complexity of the underlying pathological processes. We also evaluate emerging therapeutic strategies targeting specific molecular pathways involved in bone formation. Understanding these intricate molecular mechanisms and their interactions is crucial for developing more effective targeted therapies that could potentially not only manage symptoms but also prevent or reverse structural damage in SpA patients.

The history of ankylosing spondylitis/axial spondyloarthritis - what is the driving force of new knowledge?

The history of (axial) spondyloarthritis has started several centuries ago. Since the end of the 19th century major achievements have been made. This historical review tries to show how closely the advances in clinical medicine in rheumatology have been related to advances made in basic sciences.

HLA-B27 and spondyloarthritis: at the crossroads of innate and adaptive immunity

HLA-B*27 confers a strong risk of developing spondyloarthritis (SpA), which includes axial SpA with or without peripheral arthritis, enthesitis, acute anterior uveitis and gastrointestinal inflammation. Although no definitive mechanism has been established to explain the role of this HLA class I protein in the pathogenesis of SpA, three main hypotheses have emerged. First is the idea that self-peptides displayed by HLA-B27 resemble microorganism-derived peptides, leading to the expansion of autoreactive CD8+ T cells that trigger disease. The second and third hypotheses focus on aberrant properties of HLA-B27, including its tendency to form cell-surface dimers that can activate innate killer immunoglobulin-like receptors on CD4+ T helper 17 cells, triggering the production of pathogenic cytokines. HLA-B27 also misfolds in the endoplasmic reticulum, which can activate the unfolded protein response, increasing IL-23 expression and thereby promoting the production of type 17 cytokines. HLA-B27 misfolding in mesenchymal stem cells has also been linked to enhanced bone formation by mesenchymal stem cell-derived osteoblasts, which could contribute to structural damage in axial SpA. In this Review we summarize prevailing ideas about the role of HLA-B27 in SpA, discuss the latest developments as well as the gaps in current knowledge, and provide recommendations for future research to address these unmet needs.

Exploring the molecular mechanism of Epimedium for the treatment of ankylosing spondylitis based on network pharmacology, molecular docking, and molecular dynamics simulations

Ankylosing spondylitis (AS) is a rheumatic disease that causes inflammation and bone formation in the spine. Despite significant advances in treatment, adverse side effects have triggered research into natural compounds. Epimedium (EP) is a traditional Chinese herb with a variety of pharmacological activities, including antirheumatic, anti-inflammatory, and immunomodulatory activities; however, its direct effects on AS treatment and the underlying molecular mechanisms have not been systematically studied. Thus, here, we used network pharmacology, molecular docking, and molecular dynamics simulations to explore the targets of EP for treating AS. We constructed an interaction network to elucidate the complex relationship between EP and AS. Sixteen active ingredients in EP were screened; 80 potential targets were identified. In particular, 8-(3-methylbut-2-enyl)-2-phenylchromone, anhydroicaritin, and luteolin were the core components and TNF, IL-6, IL-1β, MMP9, and PTGS2 were the core targets. The GO and KEGG analyses indicated that EP may modulate multiple biological processes and pathways, including the AGE-RAGE, TNF, NF-κB/MAPK, and TLR signaling pathways, for AS treatment. Molecular docking and molecular dynamics simulations showed good affinity between the active components and core targets of EP, with stable binding within 100 nanoseconds. In particular, 8-(3-methylbut-2-enyl)-2-phenylchromone possessed the highest free energy of binding to PTGS2 and TNF (-115.575 and - 87.676 kcal/mol, respectively). Thus, EP may affect AS through multiple pathways, including the alleviation of inflammation, oxidative stress, and immune responses. In summary, we identified the active components and potential targets of EP, highlighting new strategies for the further experimental validation and exploration of lead compounds for treating AS.

Fast, Present and Future of the Concept of Spondyloarthritis

PURPOSE OF REVIEW

Axial spondyloarthritis (axSpA) is a rather prevalent chronic inflammatory rheumatic disease that affects already relatively young patients. It has been known better since the end of the nineteenth century but quite a lot has been learned since the early 60ies when the first classification (diagnostic) criteria for ankylosing spondylitis (AS) were agreed on. I have been part of many developments in the last 30 years, and I'm happy to have been able to contribute to the scientific progress in terms of diagnosis, imaging, pathophysiology and therapy. When I was asked to write a manuscript about the SpA concept I felt honored. Thus, the purpose of this extensive review was, on the one hand, to describe the history of AS and axSpA, and on the other hand, to reason about the concept and the gestalt of axSpA, and finally to deliver some ideas what future researchers could possibly do to further study the disease.

RECENT FINDINGS

The last 3 decades were full of innovations for both, classification and treatment of axSpA which also helped us to learn about the pathophysiology. Thus, TNFa, IL-17, IL-23 and Janus kinase are established targets to reduce inflammation. IL-17 and IL-23 are very special in that regard because they both work for psoriasis but only anti-IL-17 agents which don't work in IBD are approved for axSpA, while IL 23 inhibitors are approved for both, psoriasis and IBD, but they don't work in axSpA. New imaging techniques such as low dose CT and synthetic MRI are likely to improve the detection of both active and structural lesions of axSpA. This manuscript tries to describe the most important findings about axSpA. The main aim of research remains to discover the pathophysiology and to further improve treatment options in order to reduce and abolish inflammation and prevent new bone formation to increase the quality of life of our patients. The differences between male and female disease and the role of the immune system in axSpA are now the main challenges, and the role of special T-cell receptors seem to deserve special interest.

Crosstalk Between Cytokines and IgG N-Glycosylation: Bidirectional Effects and Relevance to Clinical Innovation for Inflammatory Diseases

The crosstalk between cytokines and immunoglobulin G (IgG) N-glycosylation forms a bidirectional regulatory network that significantly impacts inflammation and immune function. This review examines how various cytokines, both pro- and anti-inflammatory, modulate IgG N-glycosylation, shaping antibody activity and influencing inflammatory responses. In addition, we explore how altered IgG N-glycosylation patterns affect cytokine production and immune signaling, either promoting or reducing inflammation. Through a comprehensive analysis of current studies, this review underscores the dynamic relationship between cytokines and IgG N-glycosylation. These insights enhance our understanding of the mechanisms underlying inflammatory diseases and contribute to improved strategies for disease prevention, diagnosis, monitoring, prognosis, and the exploration of novel treatment options. By focusing on this crosstalk, we identify new avenues for developing innovative diagnostic tools and therapies to improve patient outcomes in inflammatory diseases.

An Actual Insight into the Pathogenic Pathways of Ankylosing Spondylitis

Spondyloarthritis refers to a broad group of conditions that include ankylosing spondylitis, psoriatic arthritis, reactive arthritis, and enteropathic arthritis associated with Crohn's disease or ulcerative colitis. They have been classified by the ASAS group (ASsessment in Ankylosing Spondylitis) into axial spondyloarthritis and peripheral spondyloarthritis. Common features include the absence of autoantibodies, genetic predisposition, and clinical aspects such as axial joint involvement, peripheral manifestations, and extra-articular involvement. However, the pathogenic mechanisms remain complex and incompletely elucidated, despite the fact that the specialized literature has described several pathways that act in synergy: genetic predisposition, environmental factors (infections and mechanical stress), or innate and acquired immune mechanisms. Finally, an inflammatory response is triggered by the recruitment of a large number of inflammatory cells and the release of innate cytokines in the affected areas: joints or periarticular or extraarticular tissues. The current article aims to update and systematize the knowledge accumulated so far on this topic, focusing on the mechanisms that have been involved in the onset, progression, and severity of ankylosing spondylitis.

Rotation or change of biotherapy after TNF blocker treatment failure for axial spondyloarthritis: the ROC-SpA study, a randomised controlled study protocol

INTRODUCTION

Axial spondyloarthritis (axSpA) is a chronic inflammatory disease characterised by inflammatory low back pain. Non-steroidal anti-inflammatory drugs (NSAIDs) are recommended as a first treatment in axSpA. In case of inadequate response to NSAIDs, biological disease-modifying antirheumatic drugs (bDMARDs) should be introduced according to the recommendations of the European League Against Rheumatism (EULAR) and the American College of Rheumatology. Until 2015, only bDMARD was recommended for axSpA in case of failure to anti-tumour necrosis factor (TNF). The 2022 Assessment of SpondyloArthritis International Society (ASAS)-EULAR recommendation proposed to start an alternative bDMARD but without advocating a switch in mode of action as proposed in rheumatoid arthritis. Since 2015, the inhibition of interleukin (IL)-17 has demonstrated efficacy in axSpA. Then, we designed a randomised multicentre clinical trial to identify the more effective treatment after a first anti-TNF failure in axSpA, comparing an anti-IL-17 to a second anti-TNF.

METHODS AND ANALYSIS

The ROC-SpA (Rotation Or Change of biotherapy after first anti-TNF treatment failure in axSpA patients) study is a prospective, randomised, multicentre, superiority open-label phase IV trial comparing an anti-IL-17 strategy (secukinumab or ixekizumab) to a second TNF blocker in a 1:1 ratio. Patients with an active axSpA (Bath Ankylosing Spondylitis Disease Activity Index >4 or ankylosing spondylitis disease activity score (ASDAS) >3.5) with inadequate 3 months response to a first anti-TNF and with a stable dose of conventional synthetic DMARDs, oral corticosteroids and/or NSAIDs for at least 1 month are included in 31 hospital centres in France and Monaco. The primary outcome is the ASAS40 response at week 24. The secondary outcomes are ASAS40 at weeks 12 and 52, other clinical scores (ASAS20, partial remission rate, ASDAS major improvement rate) at weeks 12, 24 and 52 with the drugs and anti-drugs concentrations at baseline, weeks 12, 24 and 52. The primary analysis is performed at the end of the study according to the intent-to-treat principle.

ETHICS AND DISSEMINATION

Ethics approval was obtained from the committee for the protection of persons (Comité de protection des personnes Ouest IV #12/18_1, 6 February 2018) and registered in ClinicalTrials.gov and in EudraCT. Results of this study, whether positive or negative, will be presented at national and international congresses, to national axSpA patient associations and published in a peer-reviewed journal. It could also impact the international recommendation to manage patients with axSpA.

TRIAL REGISTRATION NUMBER

NCT03445845 and EudraCT2017-004700-22.

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.

Axial Spondyloarthritis: an overview of the disease

Axial Spondyloarthritis (axSpA) is a chronic, inflammatory, immune-mediated rheumatic disease that comprises two subsets, non-radiographic and radiographic axSpA, and belongs to a heterogeneous group of spondyloarthritides (SpA). Over the years, the concept of SpA has evolved significantly, as reflected in the existing classification criteria. Considerable progress has been made in understanding the genetic and immunological basis of axSpA, in studying the processes of chronic inflammation and pathological new bone formation, which are pathognomonic for the disease. As a result, new medication therapies were developed, which bring more effective ways for disease control. This review presents a brief overview of the literature related to these aspects of disease after summarising the available information on the topic that we considered relevant. Specifically, it delves into recent research illuminating the primary pathological processes of enthesitis and associated osteitis in the context of inflammation in axSpA. The exploration extends to discussion of inflammatory pathways, with a particular focus on Th1/Th17-mediated immunity and molecular signaling pathways of syndesmophyte formation. Additionally, the review sheds light on the pivotal role of cytokine dysregulation, highlighting the significance of the IL-23/17 axis and TNF-α in this intricate network of immune responses which is decisive for therapeutic approaches in the disease.

Identification of key genes with abnormal RNA methylation modification and selected m6A regulators in ankylosing spondylitis

BACKGROUND

N6-methyladenosine (m6A) has been identified as the most abundant modification of RNA molecules and the aberrant m6A modifications have been associated with the development of autoimmune diseases. However, the role of m6A modification in ankylosing spondylitis (AS) has not been adequately investigated. Therefore, we aimed to explore the significance of m6A regulator-mediated RNA methylation in AS.

METHODS

The methylated RNA immunoprecipitation sequencing (meRIP-seq) and digital RNA sequencing (Digital RNA-seq) were conducted using the peripheral blood mononuclear cells from three AS cases and three healthy controls, to identify genes affected by abnormal RNA methylation. The genes associated with different peaks were cross-referenced with AS-related genes obtained from the GeneCards Suite. Subsequently, the expression levels of shared differentially expressed genes (DEGs) and key m6A regulators in AS were evaluated using data from 68 AS cases and 36 healthy controls from two data sets (GSE25101 and GSE73754). In addition, the results were validated through quantitative polymerase chain reaction (qPCR).

RESULTS

The meRIP-seq and Digital RNA-seq analyses identified 28 genes with upregulated m6A peaks but with downregulated expression, and 52 genes with downregulated m6A peaks but with upregulated expression. By intersecting the genes associated with different peaks with 2184 AS-related genes from the GeneCards Suite, we identified a total of five shared DEGs: BCL11B, KAT6B, IL1R1, TRIB1, and ALDH2. Through analysis of the data sets and qPCR, we found that BCL11B and IL1R1 were differentially expressed in AS. Moreover, two key m6A regulators, WTAP and heterogeneous nuclear ribonucleoprotein C, were identified.

CONCLUSIONS

In conclusion, the current study revealed that m6A modification plays a crucial role in AS and might hence provide a new treatment strategy for AS disease.

Sacroiliitis in inflammatory bowel disease

PURPOSE OF REVIEW

This review summarizes the recent evidence regarding the epidemiology of inflammatory bowel disease (IBD) associated sacroiliitis, including the prevalence, pathogenesis, role of imaging, and therapeutic challenges.

RECENT FINDINGS

Sacroiliitis is an underappreciated musculoskeletal manifestation of IBD, a chronic inflammatory condition of the gut affecting the younger population. Untreated sacroiliitis can lead to joint destruction and chronic pain, further adding to morbidity in IBD patients. Recent publications suggest sacroiliitis can be detected on abdominal imaging obtained in IBD patients to study bowel disease, but only a small fraction of these patients were seen by rheumatologists. Early detection of IBD-associated sacroiliitis could be achieved by utilization of clinical screening tools in IBD clinics, careful examination of existing computed tomography and MRI studies, and timely referral to rheumatologist for further evaluation and treatment. Current treatment approaches for IBD and sacroiliitis include several targeted biologic therapies, but IBD-associated sacroiliitis has limited options, as these therapies may not overlap in both conditions.

SUMMARY

With the advances in imaging, sacroiliitis is an increasingly recognized comorbidity in IBD patients. Future studies focusing on this unique patient population will expand our understanding of complex pathophysiology of IBD-associated sacroiliitis and lead to identification of novel targeted therapies for this condition.

An update in the pharmacological management of axial spondyloarthritis

INTRODUCTION

Significant progress has been made in the diagnosis and management of axial spondyloarthritis (AxSpA) over recent decades. A greater understanding of the immunopathogenesis of the disease has paved the way for the development of targeted treatments. Their efficacy has been demonstrated in randomized controlled trials, meta-analyses and one head-to-head study of biologic DMARDs. Treatment decisions in AxSpA are currently influenced by patient choice, co-morbidity, clinician familiarity and cost.

AREAS COVERED

We review the clinical trials that underpin the evidence base for treatments in AxSpA. We also cover the meta-analyses and head-to-head data that seek to support clinicians in personalizing treatment decisions. Further, we discuss the recent international guidelines that provide clinicians with treatment pathways and guidance.

EXPERT OPINION

We conclude that treatment decisions in managing both radiographic and non-radiographic AxSpA should be based on shared decision-making with patients, the clinical effectiveness of drug class, co-morbidity and cost. At present, we have limited head-to-head data to prioritize one drug class over another for first-line treatment but can recommend tumor necrosis factor (TNF), interleukin 17 (IL17) and JAK inhibition as being comparable in terms of clinical, structural and patient-reported outcome measures. Further real-world data may guide treatment decision-making in individual patients.

A review of long non-coding RNAs in ankylosing spondylitis: pathogenesis, clinical assessment, and therapeutic targets

Ankylosing spondylitis (AS) is a chronic immune-mediated type of inflammatory arthritis characterized by inflammation, bone erosion, and stiffness of the spine and sacroiliac joints. Despite great efforts put into the investigation of the disease, the pathogenesis of AS remains unclear, posing challenges in identifying ideal targets for diagnosis and treatment. To enhance our understanding of AS, an increasing number of studies have been conducted. Some of these studies reveal that long non-coding RNAs (lncRNAs) play crucial roles in the etiology of AS. Some certain lncRNAs influence the development of AS by regulating inflammatory responses, autophagy, apoptosis, and adipogenesis, as well as the proliferation and differentiation of cells. Additionally, some lncRNAs demonstrate potential as biomarkers, aiding in monitoring disease progression and predicting prognosis. In this review, we summarize recent studies concerning lncRNAs in AS to elucidate the underlying mechanisms in which lncRNAs are involved and their potential values as biomarkers for disease assessment and druggable targets for therapy.

Efficacy of TNF-α Inhibitors in the Treatment of nr-axSpA: A Systematic Review and Meta-Analysis Based on Randomized Controlled Trials

INTRODUCTION

A growing number of randomized controlled trials (RCTs) have demonstrated the effectiveness of tumor necrosis factor-α (TNF-α) inhibitors in treating non-radiographic axial spondyloarthritis (nr-axSpA). This study aimed to evaluate the efficacy of TNF-α inhibitors in the treatment of nr-axSpA.

METHODS

PubMed, EMBASE, Web of Science, and the Cochrane Library databases were systematically searched for relevant RCTs using specific keywords up to June 2023. The primary outcome was the proportion of patients who achieved Assessment in SpondyloArthritis international Society 40% (ASAS40). Secondary outcomes included ASAS20, Bath Ankylosing Spondylitis Disease Activity Index 50% (BASDAI50), ASAS partial remission, and ASAS5/6.

RESULTS

A total of eight RCTs involving 1,376 patients were included. Patients receiving anti-TNF therapy exhibited a higher rate of ASAS40 (pooled RR = 2.36; 95% CI: 1.63-3.42; p < 0.001). In addition, the TNF-α inhibitor group showed higher BASDAI50 rates (pooled RR = 2.06; 95% CI: 1.48-2.89), ASAS20 rates (pooled RR = 1.48; 95% CI: 1.31-1.67), ASAS partial remission rates (pooled RR = 2.33; 95% CI: 1.58-3.43), and ASAS5/6 rates (RR = 3.46; 95% CI: 2.05-5.83) than the placebo group.

CONCLUSION

The TNF-α inhibitors were effective in treating nr-axSpA.

Clinically relevant differences in spinal mobility related to daytime performance in patients with axial spondyloarthritis

OBJECTIVE

Patients with axial spondyloarthritis (axSpA) suffer from clinical symptoms like morning stiffness and back pain. Mobility of patients with axSpA is often impaired. The aim of this study is to compare the performance of patients with axSpA regarding mobility measures including performance-based tests and objective electronic assessments with the Epionics SPINE device (ES) at different times of the day compared with healthy controls (HC).

METHODS

Observational trial, consecutive inpatients with axSpA (n=100) and 20 HCs were examined in the morning (V1: before 10:00 am) and in the afternoon (V2: after 02:00 pm) by the Bath Ankylosing Spondylitis Metrology Index (BASMI), the AS physical performance index (ASPI), the Short Physical Performance Battery (SPPB) and ES measurements, including range of motion (RoM) and range of kinematics (RoK).

RESULTS

The assessments of patients with axSpA performed in the morning clearly differed from those in the afternoon, especially regarding performance-based tests. Significant improvements were seen for BASMI (4.0±3.8 to 3.8±1.9; p<0.001), ASPI (36.2±18.3 to 28.8±11.9 s; p<0.001), SPPB (10.1±1.5 to 10.7±1.4 points; p<0.001) and for ES measures of speed (RoK; p<0.018) but not for RoM, except for lateral flexion (13.3±7.4 to 14.7±8.2°; p=0.002). This time of assessment-related variability was not observed in HC.

CONCLUSION

The spinal mobility of patients with axSpA was worse in the morning but significantly improved in the afternoon. This was captured best by performance-based measures and was not seen in HC. The diurnal variation of mobility has implications for clinical studies, suggesting that the time of assessments needs to be standardised.

Tetrahedral Framework Nuclear Acids Can Regulate Interleukin-17 Pathway to Alleviate Inflammation and Inhibit Heterotopic Ossification in Ankylosing Spondylitis

Ankylosing spondylitis (AS) is a chronic systemic inflammatory disease that leads to serious spinal deformity and ankylosis. Persistent inflammation and progressive ankylosis lead to loss of spinal flexibility in patients with AS. Tetrahedral framework nucleic acids (tFNAs) have emerged as a one kind of nanomaterial composed of four specially designed complementary DNA single strands with outstanding biological properties. Results from in vivo experiments demonstrated that tFNAs treatment could inhibit inflammatory responses and heterotopic ossification to halt disease progression. In vitro, tFNAs were proved to influence the biological behavior of AS primary chondrocytes and inhibit the secretion of pro-inflammatory cytokines through interleukin-17 pathway. The osteogenic process of chondrocytes was as well inhibited at the transcriptional level to regulate the expression of related proteins. Therefore, we believe tFNAs had a strong therapeutic effect and could serve as a nonsurgical remedy in the future to help patients suffering from AS.

Down-regulation of long noncoding RNA HULC inhibits the inflammatory response in ankylosing spondylitis by reducing miR-556-5p-mediated YAP1 expression

OBJECTIVE

Ankylosing spondylitis (AS) is a progressive systemic disease characterized by a chronic inflammatory response in the sacroiliac joints and spine. Long noncoding RNAs suggest significant actions in the progression of AS. Therefore, a specific lncRNA, highly upregulated in liver cancer (HULC), was studied here regarding its functions and related mechanisms in AS.

METHODS

Measurements of miR-556-5p, HULC, and YAP1 expression were performed on AS cartilage tissues and chondrocytes. The interaction between miR-556-5p and HULC or YAP1 was verified. CCK-8, flow cytometry and enzyme-linked immunosorbent assay were used to evaluate the effects of HULC, miR-556-5p, and YAP1 on the proliferation, apoptosis, and inflammatory response of AS chondrocytes. Furthermore, the action of HULC/miR-556-5p/YAP1 was experimentally observed in AS mice.

RESULTS

HULC and YAP1 levels were augmented, while miR-556-5p levels were suppressed in AS cartilage tissues and chondrocytes. Downregulating HULC or upregulating miR-556-5p stimulated chondrocyte proliferation and inhibited apoptosis and inflammation in AS. miR-556-5p was a downstream factor of HULC, and YAP1 was a potential target of miR-556-5p. The improvement effect of downregulated HULC on AS chondrocytes was saved when YAP1 expression was forced. In addition, silence of HULC improved the pathological injury of spinal cartilage in AS mice by enhancing miR-556-5p-related regulation of YAP1.

CONCLUSION

HULC inhibition relieves the inflammatory response in AS by reducing miR-556-5p-mediated YAP1 expression.

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.

Novel insights into the anatomy and histopathology of the sacroiliac joint and correlations with imaging signs of sacroiliitis in case of axial spondyloarthritis

For a better understanding of the pathophysiology of spondyloarthropathy (SpA), a detailed anatomical description of the sacroiliac joint is required because sacroiliitis is the earliest and most common sign of SpA and an essential feature for the diagnosis of ankylosing spondylitis. Beyond the anatomy, the histopathology of sacroiliac entheses and immunological mechanisms involved in sacroiliitis are crucial for a better understanding of disease causation. In this narrative review, we discuss the core anatomical, histological, and immunohistological observations involved in the development of sacroiliitis, focusing particularly on imaging-based information associated with sacroiliitis. Finally, we try to answer the question of whether at the sacroiliac joint, enthesitis precedes synovitis and subchondral bone changes in SpA.

Uncovering the Underworld of Axial Spondyloarthritis

Axial spondyloarthritis (axial-SpA) is a multifactorial disease characterized by inflammation in sacroiliac joints and spine, bone reabsorption, and aberrant bone deposition, which may lead to ankylosis. Disease pathogenesis depends on genetic, immunological, mechanical, and bioenvironmental factors. HLA-B27 represents the most important genetic factor, although the disease may also develop in its absence. This MHC class I molecule has been deeply studied from a molecular point of view. Different theories, including the arthritogenic peptide, the unfolded protein response, and HLA-B27 homodimers formation, have been proposed to explain its role. From an immunological point of view, a complex interplay between the innate and adaptive immune system is involved in disease onset. Unlike other systemic autoimmune diseases, the innate immune system in axial-SpA has a crucial role marked by abnormal activity of innate immune cells, including γδ T cells, type 3 innate lymphoid cells, neutrophils, and mucosal-associated invariant T cells, at tissue-specific sites prone to the disease. On the other hand, a T cell adaptive response would seem involved in axial-SpA pathogenesis as emphasized by several studies focusing on TCR low clonal heterogeneity and clonal expansions as well as an interindividual sharing of CD4/8 T cell receptors. As a result of this immune dysregulation, several proinflammatory molecules are produced following the activation of tangled intracellular pathways involved in pathomechanisms of axial-SpA. This review aims to expand the current understanding of axial-SpA pathogenesis, pointing out novel molecular mechanisms leading to disease development and to further investigate potential therapeutic targets.

Emerging therapies for the treatment of spondyloarthritides with focus on axial spondyloarthritis

INTRODUCTION

Spondyloarthritides (SpA) such as axial spondyloarthritis (axSpA) including ankylosing spondylitis (AS) and psoriatic arthritis (PsA) including psoriasis are chronic immune-mediated disorders with involvement of tumor necrosis factor (TNF), interleukin (IL)-17 cytokines, and janus kinases (JAK) in their pathogenesis, with IL-23 clearly also playing a role in psoriasis, PsA, and chronic inflammatory bowel diseases.

AREAS COVERED

In this narrative review, we focus on a biologic disease modifying anti-rheumatic drug (bDMARD), the bispecific IL-17A and IL-17 F inhibitor bimekizumab, and a targeted synthetic (ts) DMARD, the JAK inhibitor (i) filgotinib - emerging agents for the treatment of axSpA. Upadacitinib, another JAKi that has recently been reviewed intensively by us is already approved for axSpA and PsA in Europe.

EXPERT OPINION

In contrast to inhibition of IL-17, JAKi also work in rheumatoid arthritis (RA), while agents inhibiting IL-17 are not, even though some effect may be there. Indeed, 4 JAKi including filgotinib are approved for RA. There are several head-to-head trials with bimekizumab in plaque psoriasis. The last one showed that the bispecific inhibition of IL-17A and IL-17 F with bimekizumab may indeed be superior to inhibition of IL-17A alone with 300 mg secukinumab (usual dosage). Whether this is also the case for treatment of axSpA and PsA remains to be shown.

Are There Signs of Enthesitis in Nail Psoriasis? An Immunohistological Study of Nail Psoriasis With and Without Psoriatic Arthritis

ABSTRACT

The concept of nail psoriasis as an entheseal-driven disease has essentially been formulated on the basis of radiological findings because it is usually not possible to obtain the tissue directly from the joints. The aim of this retrospective study was to evaluate the histological features of isolated nail psoriasis with and without distal interphalangeal psoriatic arthritis (PsA), focusing on the question as to whether the fascia and adipose tissue surrounding the apex of the nail unit genuinely show an inflammatory infiltrate. In support of the nail-enthesitis theory, an ongoing inflammatory infiltrate could be expected. An immunohistochemical study was performed to evaluate the distribution and phenotype of the inflammatory infiltrate in nail psoriasis with and without PsA. This study did not show an inflammatory infiltrate in the fascia connecting the nail to the extensor tendon. CD8 and CD4 subsets were present in equal number in the nail dermis of nail psoriasis with or without PsA, which is a similar distribution to that seen in psoriatic synovium while skin psoriasis is characterized by a dermal predominance of CD4 T lymphocytes. Because of this study and recent microanatomic studies of the normal nail unit, it is possible to move away from a purely anatomic explanation of the strong association between nail psoriasis and PsA and to propose immunological factors as contributory. This study provides support for the hypothesis that CD8+ T cells play a crucial role in the pathogenesis of nail psoriasis through a pathogenic pathway similar to that of PsA and contrasting with that of the skin.

How Has Molecular Biology Enhanced Our Undertaking of axSpA and Its Management

PURPOSE

This review aims at investigating pathophysiological mechanisms in spondyloarthritis (SpA). Analysis of genetic factors, immunological pathways, and abnormalities of bone metabolism lay the foundations for a better understanding of development of the axial clinical manifestations in patients, allowing physician to choose the most appropriate therapeutic strategy in a more targeted manner.

RECENT FINDINGS

In addition to the contribution of MHC system, findings emerged about the role of non-HLA genes (as ERAP1 and 2, whose inhibition could represent a new therapeutic approach) and of epigenetic mechanisms that regulate the expression of genes involved in SpA pathogenesis. Increasing evidence of bone metabolism abnormalities secondary to the activation of immunological pathways suggests the development of various bone anomalies that are present in axSpA patients. SpA are a group of inflammatory diseases with a multifactorial origin, whose pathogenesis is linked to the genetic predisposition, the action of environmental risk factors, and the activation of immune response. It is now well known how bone metabolism leads to long-term structural damage via increased bone turnover, bone loss and osteoporosis, osteitis, erosions, osteosclerosis, and osteoproliferation. These effects can exist in the same patient over time or even simultaneously. Evidence suggests a cross relationship among innate immunity, autoimmunity, and bone remodeling in SpA, making treatment approach a challenge for rheumatologists. Specifically, treatment targets are consistently increasing as new drugs are upcoming. Both biological and targeted synthetic drugs are promising in terms of their efficacy and safety profile in patients affected by SpA.

Immune mechanism of low bone mineral density caused by ankylosing spondylitis based on bioinformatics and machine learning

Background and Objective: This study aims to find the key immune genes and mechanisms of low bone mineral density (LBMD) in ankylosing spondylitis (AS) patients. Methods: AS and LBMD datasets were downloaded from the GEO database, and differential expression gene analysis was performed to obtain DEGs. Immune-related genes (IRGs) were obtained from ImmPort. Overlapping DEGs and IRGs got I-DEGs. Pearson coefficients were used to calculate DEGs and IRGs correlations in the AS and LBMD datasets. Louvain community discovery was used to cluster the co-expression network to get gene modules. The module most related to the immune module was defined as the key module. Metascape was used for enrichment analysis of key modules. Further, I-DEGs with the same trend in AS and LBMD were considered key I-DEGs. Multiple machine learning methods were used to construct diagnostic models based on key I-DEGs. IID database was used to find the context of I-DEGs, especially in the skeletal system. Gene-biological process and gene-pathway networks were constructed based on key I-DEGs. In addition, immune infiltration was analyzed on the AS dataset using the CIBERSORT algorithm. Results: A total of 19 genes were identified I-DEGs, of which IFNAR1, PIK3CG, PTGER2, TNF, and CCL3 were considered the key I-DEGs. These key I-DEGs had a good relationship with the hub genes of key modules. Multiple machine learning showed that key I-DEGs, as a signature, had an excellent diagnostic performance in both AS and LBMD, and the SVM model had the highest AUC value. Key I-DEGs were closely linked through bridge genes, especially in the skeletal system. Pathway analysis showed that PIK3CG, IFNAR1, CCL3, and TNF participated in NETs formation through pathways such as the MAPK signaling pathway. Immune infiltration analysis showed neutrophils had the most significant differences between case and control groups and a good correlation with key I-DEG. Conclusion: The key I-DEGs, TNF, CCL3, PIK3CG, PTGER2, and IFNAR1, can be utilized as biomarkers to determine the risk of LBMD in AS patients. They may affect neutrophil infiltration and NETs formation to influence the bone remodeling process in AS.

Association of anti-TNF-α treatment with gut microbiota of patients with ankylosing spondylitis

OBJECTIVE

Gut dysbiosis contributes to multiple autoimmune diseases, including ankylosing spondylitis, which is commonly treated with tumor necrosis factor (TNF)-α inhibitors (TNFis). Because host TNF-α levels are considered to interact with gut microbiota, we aimed to systematically investigate the microbiota profile of ankylosing spondylitis patients with anti-TNF-α-based treatment and identify potential key bacteria.

METHODS

Fecal samples were collected from 11 healthy controls and 24 ankylosing spondylitis patients before/after anti-TNF-α treatment, the microbiota profiles of which were evaluated by 16S ribosomal DNA amplicon sequencing and subsequent bioinformatic analysis.

RESULTS

Significantly different microbial compositions were observed in samples from ankylosing spondylitis patients compared with healthy controls, characterized by a lower abundance of short-chain fatty acid (SCFA)-producing bacteria. All patients exhibited a positive response after anti-TNF-α treatment, accompanied by a trend of restoration in the microbiota compositions and functional profile of ankylosing spondylitis patients to healthy controls. In particular, the abundance of SCFA-producing bacteria (e.g. Megamonsa and Lachnoclostridium ) was not only significantly lower in ankylosing spondylitis patients than in healthy controls and restored after anti-TNF-α treatment but also negatively correlated with disease severity (e.g. cor  = -0.52, P  = 8 × 10 -5 for Megamonsa ). In contrast, Bacilli and Haemophilus may contribute to ankylosing spondylitis onset and severity.

CONCLUSIONS

Microbiota dysbiosis in ankylosing spondylitis patients can be restored after anti-TNF-α treatment, possibly by impacting SCFA-producing bacteria.

Concise report: a minimal-invasive method to retrieve and identify entheseal tissue from psoriatic arthritis patients

OBJECTIVES

To establish a minimally invasive biopsy technique for the analysis of entheseal tissue in patients with psoriatic arthritis (PsA).

METHODS

Human cadavers were used for establishing the technique to retrieve tissue from the lateral humeral epicondyle enthesis (cadaveric biopsies). After biopsy, the entire enthesis was surgically resected (cadaveric resections). Biopsies and resections were assessed by label-free second harmonic generation (SHG) microscopy. The same technique was then applied in patients with PsA with definition of entheseal tissue by SHG, staining of CD45+immune cells and RNA extraction.

RESULTS

Entheseal biopsies from five cadavers allowed the retrieval of entheseal tissue as validated by the analysis of resection material. Microscopy of biopsy and resection sections allowed differentiation of entheseal, tendon and muscle tissue by SHG and definition of specific intensity thresholds for entheseal tissue. In subsequent entheseal biopsies of 10 PsA patients: the fraction of entheseal tissue was high (65%) and comparable to cadaveric biopsies (68%) as assessed by SHG microscopy. Furthermore, PsA biopsies showed immune cell infiltration and sufficient retrieval of RNA for further molecular analysis.

CONCLUSION

Entheseal biopsy of the lateral epicondyle is feasible in patients with PsA allowing reliable retrieval of entheseal tissue and its identification by SHG microscopy.

Spondyloarthropathy in Inflammatory Bowel Disease: From Pathophysiology to Pharmacological Targets

Spondyloarthritis (SpA) represents one of the most frequent extraintestinal manifestations of inflammatory bowel disease (IBD). Evidence of shared genetic and molecular pathways underlying both diseases is emerging, which has led to rational approaches when treating patients with concomitant diseases. Clinical efficacy of tumor necrosis factor (TNF) antagonists has been ascertained over the years, and they currently represent the cornerstone of treatment in patients with IBD and SpA, but the therapeutic armamentarium in these cases has been recently expanded. Evidence for vedolizumab is controversial, as it was associated both with improvement and development of arthralgias, while ustekinumab, the first anti-interleukin 12/23 (IL-12/23) approved for IBD, has demonstrated good efficacy, especially in peripheral arthritis, and more IL-23 inhibitors are being developed in IBD. Tofacitinib was the first Janus kinase (JAK) inhibitor to be approved in IBD, and as it demonstrated efficacy in treating ankylosing spondylitis, it may represent a good choice in axial arthritis, while more selective JAK inhibitors are yet to be approved. Unexpectedly, the first anti-IL17 that was studied in IBD (secukinumab) has shown not to be effective in treating IBD, and the role of anti-IL17 drugs in these diseases needs further investigation. Therefore, as availability of biologics and small molecules is increasing, their positioning in clinical practice is becoming more and more challenging, and multidisciplinary management needs to be implemented in both research and clinical settings in order to enhance early recognition of SpA in IBD patients, optimize treatment and ultimately improve the patients' quality of life.

Investigating the Molecular Mechanism of Qianghuo Shengshi Decoction in the Treatment of Ankylosing Spondylitis Based on Network Pharmacology and Molecular Docking Analysis

Background: Qianghuo Shengshi decoction (QHSSD), a traditional Chinese medicine formula, is used to treat ankylosing spondylitis (AS) in China. The pharmacological mechanism of QHSSD for AS remains to be clarified. In this study, we investigated the molecular mechanisms of QHSSD in the treatment of AS using network pharmacology and molecular docking. Methods: To obtain the chemical components and potential targets of QHSSD, we used the Traditional Chinese Medicine Systematic Pharmacology Database and Analysis Platform (TCMSP) and SwissTargetPrediction. AS potential targets were found in the GeneCards, OMIM, and DisGenets databases. A Venn diagram was used to screen QHSSD and AS common potential targets. The STRING website and Cytoscape software were used to create and analyze protein–protein interactions and component–target networks. The DAVID database was used for the gene ontology (GO) function and Kyoto Encyclopedia of Genes and Genomes (KEGG) pathway enrichment analysis. Molecular docking was used to visualize drug–target interactions. Results: The component–target network consisted of 119 chemical components and 193 potential targets. QHSSD was implicated in various biological processes, such as inflammation and angiogenesis, and mediated multiple signaling pathways, such as the MAPK signaling pathway. Molecular docking revealed good binding ability between medicarpin, notoptol, vitetrifolin E, and cnidilin and EGFR, TNF-α, ALB, and VEGFA. Conclusions: The chemical compositions, potential targets, and pathways involved in the QHSSD treatment of AS were successfully predicted in this study. This study provides a solid foundation for the selection of drugs to treat AS.

Effectiveness of thalidomide for ankylosing spondylitis: a meta-analysis of randomized controlled trials in China

Several studies have demonstrated the benefits of thalidomide as a treatment for patients with ankylosing spondylitis (AS); however, published literature reported controversial results. We conducted a meta-analysis to systematically evaluate the efficacy of thalidomide in AS patients. PubMed, Embase, Cochrane Library, Web of Science, Wanfang Data, and China National Knowledge Infrastructure (CNKI) were searched for relevant studies. The Q test and I² statistic were used to examine between-study heterogeneity. Fixed- or random-effects models were selected based on study heterogeneity. The risk difference (RD), absolute risk reduction (ARR), and weighted mean difference (WMD) with 95% confidence intervals (CI) were pooled for dichotomous or continuous data, as appropriate. Sensitivity analyses, funnel plots, and the Begg's tests were also performed. Overall, 19 trials with 1471 patients were included. The effectiveness of thalidomide alone and combined with other drugs was significantly higher than the control group, and the pooled RDs were 0.15 (95% CI: 0.10-0.20, I² = 0%) and 0.20 (95% CI: 0.14-0.25, I² = 13.4%), respectively. Thalidomide treatment yielded significant improvements in secondary outcomes for patients with AS. The adverse reaction rate for thalidomide alone was low than that for the control group (ARR = 0.08, 95% CI: 0.01-0.15, I² = 0.0%), while there was no significant difference in the safety between the group in which thalidomide was combined with other drugs and the control (ARR = 0.03, 95% CI: - 0.04-0.10, I² = 41.1%). The findings suggest that thalidomide improves the effectiveness of AS treatment, which should be considered by physicians. However, owing to the inclusion of several low-quality and Chinese studies, additional rigorous randomized controlled trials (RCTs) are needed in the future to confirm the results of this meta‑analysis.

The Associations of rs1799724 and rs361525 With the Risk of Ankylosing Spondylitis Are Dependent on HLA-B27 Status in a Chinese Han Population

Objectives

Human leucocyte antigen B27 (HLA-B27) is an important biomarker for ankylosing spondylitis (AS). However, delay in the diagnosis of AS is still common in clinical practice. Several single nucleotide polymorphisms (SNPs) in the coding gene of tumor necrosis factor alpha (TNFα) have been reported to be AS susceptibility loci. Our aim was to explore whether SNPs in TNFα could be used to improve the performance of HLA-B27 for predicting AS.

Methods

Five SNPs (rs1799964, rs1800630, rs1799724, rs1800629, and rs361525) spanning TNFα were genotyped by qPCR-Invader assay in 93 AS patients and 107 healthy controls for association analysis and linkage disequilibrium (LD) analysis. Random forest algorithm was utilized to construct the predictive classifiers for AS. HLA-B was genotyped by PCR-sequence-based typing in a subset of the HLA-B27-positive subjects (38 AS patients and 5 healthy controls).

Results

The T allele of rs1799724 was verified to significantly increase the risk of AS (OR = 4.583, p < 0.0001), while the A allele of rs361525 showed an association with the reduced AS risk (OR = 0.168, p = 0.009). In addition, the rs1799964^T-rs1800630^C-rs1799724^T-rs1800629^G-rs361525^G haplotype was significantly associated with a higher risk of AS (p < 0.0001). The optimal set of variables for classifiers to predict AS only consisted of HLA-B27. Strong associations with HLA-B27 status were found in both rs1799724 (p < 0.0001) and rs361525 (p = 0.001), and all the analyzed HLA-B27-positive subjects carried HLA-B*27:04 or HLA-B*27:05.

Conclusion

In the Chinese Han population, the minor allele T of rs1799724 could increase the risk of AS, while the minor allele A of rs361525 protects individuals from AS. However, the contributions of rs1799724 and rs361525 to AS risk were dependent on HLA-B27 status, suggesting the importance of taking the independence and specificity into consideration in AS susceptibility loci studies.

Treatment of axial spondyloarthritis: an update

Diagnosis and management of axial spondyloarthritis (axSpA) has vastly improved over the past two decades. With advances in the discernment of immunopathogenesis of this disease, new therapies have become available, which are associated with substantial improvement in symptoms, signs and quality of life. The four broad categories of approved treatment options are physical therapy and exercise (which have been known to be beneficial for millennia), NSAIDs (since the 1950s), TNF inhibitors (first FDA approval in 2003) and IL-17 inhibitors (first FDA approval in 2016). In addition, there have been a host of new developments in the axSpA field, including new treatment guidelines, the FDA approval of three biologic DMARDs to treat non-radiographic axSpA, the FDA and EMA approval of Janus kinase (JAK) inhibitors for ankylosing spondylitis, new data on the effect of biologic DMARDs on structural progression in ankylosing spondylitis, strategy trials on tapering or stopping TNF inhibitors in patients in remission, trials of treat-to-target strategy in axSpA, and several new molecules in phase III studies. This Review explores the developments in the management of axSpA.

[Answering epidemiologic rheumatologic questions by cooperation with the large population-based SHIP cohort-findings with relevance for the diagnosis of axial spondyloarthritis (axSpA)]

This article presents how, based on the availability of new imaging methods and medications, objectives regarding the rheumatic disease axial spondyloarthritis (axSpA) have developed over the course of more than two decades into a rheumatologic research group. During recent years, cooperation with the Study of Health in Pomerania (SHIP) cohort has given rise to new fundamental aspects. This involved intensive cooperation between the Ruhr University Bochum (Rheumazentrum Ruhrgebiet) and the Greifswald University Hospital (Community Medicine research collective). The design of the SHIP cohort was published 10 years ago and the cohort approach presented in the Bundesgesundheitsblatt, which also described central methodologic questions in detail. In 2014, a cooperation project between the Ruhr Rheumatology Center/Ruhr University Bochum and the SHIP Department of Clinical and Epidemiologic Research (Klinisch-Epidemiologische Forschung, KEF; SHIP-KEF) was established, which has already resulted in publication of interesting results in high-ranking journals. In order to stress the potential of such corporations, important contents thereof are presented herein, with a focus on MRI and consideration of historical aspects.

[Hyperactivation of PI3K/AKT/mTOR signal pathway impairs TNF-α-induced autophagy in mesenchymal stem cells from patients with ankylosing spondylitis]

OBJECTIVE

To investigate the changes in autophagy of mesenchymal stem cells (MSCs) from patients with ankylosing spondylitis and explore the mechanism for decreased autophagy in ASMSCs.

METHODS

MSCs collected from 14 patients with AS (ASMSCs) and from 15 healthy donors (HDMSCs) were cultured in the absence or presence of 25 ng/mL TNF-α for 6 h. Autophagy of the cells was determined by immunofluorescence staining of GFP-LC3B, and the results were confirmed by detecting the protein expressions of autophagy markers LC3 II/LC3 I and P62. The mRNA expressions of the related genes were detected using qRT-PCR, and the protein expressions of the autophagy markers and signaling pathway-related molecules were determined with Western blotting. TG100713 was used to block the PI3K/AKT/mTOR signal pathway, and its effect on autophagy of ASMSCs was evaluated.

RESULTS

ASMSCs showed significantly weaker GFP-LC3B puncta staining and lower protein expression levels of LC3 II/LC3 I but higher levels of P62 protein (P < 0.05), indicating a decreased autophagy capacity as compared with HDMSCs. TNF-α-induced ASMSCs showed significantly higher protein expressions of p-PI3K/ PI3K, p-AKT/AKT and p-mTOR/mTOR than HDMSCs (P < 0.05), suggesting hyperactivation of the PI3K/AKT/mTOR signaling pathway in ASMSCs. Blocking PI3K/AKT/mTOR signaling with TG100713 eliminated the difference in TNF-α-induced autophagy between HDMSCs and ASMSCs.

CONCLUSION

In patients with AS, hyperactivation of the PI3K/AKT/mTOR signaling pathway results in decreased autophagy of the MSCs and potentially contributes to chronic inflammation.

New developments in ankylosing spondylitis-status in 2021

Axial SpA (axSpA) is a common rheumatic disease characterized by inflammation leading to bone formation and functional impairment. TNF-α and IL-17 represent established targets in axSpA. TNF-α and IL-17 inhibitors have demonstrated efficacy in clinical trials and are currently approved biologic DMARDs for all subsets of the disease. Several lines of evidence implicate a role of an IL-23–IL-17 axis in the disease pathogenesis. In this light, and given the success of IL-17 blockade in axSpA, a similar good response to IL-23 was anticipated. Nevertheless, two clinical trials of anti-IL-23 monoclonal antibodies in axSpA have clearly exhibited negative results. This failure has raised theories for a degree of IL-23 independent pathway. The Janus kinase (JAK) pathway is also a potential therapeutic target, since several cytokines, including those involved in the IL-23–IL-17 axis, signal through the JAK family of tyrosine kinases. Further studies and more extended evaluation of response to cytokine inhibition across different tissues will be required to improve our understanding of SpA pathogenesis and determine its optimal management.

Focal Synovial Inflammation Versus Enthesitis Theory in Distal Psoriatic Arthritis: A Pioneer Histopathologic Study

ABSTRACT

The aim of this analysis was to re-examine the classical concept of distal interphalangeal joint (DIP) psoriatic arthritis (PsA) as an entheseal-driven disease. Two cadaveric fingers with severe psoriatic arthritis were analyzed. Our results demonstrate that inflammation of DIP PsA is multifocal without interconnection between entheses and articular cartilage of the DIP. We found a clear association between synovitis and focal loss of articular cartilage at the head of the intermediate phalanx. By contrast, the articular cartilage adjacent to the zone of severe enthesitis did not show notable damage. Fibrocartilaginous destructions of enthesis were characterized by either a multifocal lymphocytic inflammation, accompanied by osteoclastic resorption, beginning on the interface between the uncalcified and calcified fibrocartilage and then extending into the bone or a subchondral bone inflammation which insidiously destroyed first the bone and then the fibrocartilage. Some sections well showed an inflammation either mild or prominent starting at the level of vascular foramina of flexor enthesis, with secondary invading into the interface between bone and enthesis. The different anatomic sites examined showed a slight predominance of CD8+ T cells over CD4+ T cells: 52% up to 63% for CD8+ T cells vs. to 36% up to 48% for CD4+ T cells. Sparse interspersed CD1a+cells and PS100+cells were also seen with a predominance of PS100+ cells on CD1a+ cells. CD20+ B cells, plasmocytes, neutrophils, and mastocytes were absent or rare. CD123 positive cells were not observed. In DIP PsA, 3 findings predominate: (1) cartilage invasion by the thin pannus offers a more rational explanation for the focal joint destruction than does inflammation of the enthesis which is independent from articular cartilage, (2) the thick ventral plate and to a lesser extend the thin dorsal plate constitute a barrier between the inflamed entheses and the articular cartilage, and (3) an unusual form of minute vascular foramen contributes to the early stage of enthesitis. This small study suggests that DIP PsA is a complex disease. It affects anatomical micro sites which, although close, are in fact relatively independent of each other. Further studies are needed to test this hypothesis.

Disease modification in ankylosing spondylitis with TNF inhibitors: spotlight on early phase clinical trials

INTRODUCTION

Ankylosing spondylitis (AS) is a chronic inflammatory disease whose main hallmark is involvement of the axial skeleton. Non-steroidal anti-inflammatory drugs (NSAIDs) are the first line treatment; however, their use is limited because of side effects. Tumor necrosis factor inhibitors (TNFi) are a safe and effective therapy, and they have been approved for the management of AS.

AREAS COVERED

This is a review of the efficacy of TNFi in disease modification in AS. It is focused on results from early-phase clinical trials; however, it also discusses the most relevant findings in order to optimize anti-TNF treatment. A literature search was done using PubMed, Medline, Embase, Google Scholar, and Cochrane library, looking for scientific publications from inception to August 2021. Further information was retrieved from ClinicalTrial.gov and Clinicaltrialsregister.eu.

EXPERT OPINION

TNFi have demonstrated short- and long-term improvements in all aspects of disease activity, as well as physical function in patients with AS. They have drastically revolutionized the management of the disease; and even though new drugs have become available in the market, TNFi has not been displaced for the treatment of AS, and still constitute the best alternative when NSAIDs are no-longer an option.

Recent Updates in Juvenile Spondyloarthritis

Spondyloarthritis represents a group of disorders characterized by enthesitis and axial skeletal involvement. Juvenile spondyloarthritis begins before age 16. Joint involvement is usually asymmetric. Bone marrow edema on noncontrast MRI of the sacroiliac joints can facilitate diagnosis. The most significant risk factor for axial disease is HLA-B27. Most patients have active disease into adulthood. Enthesitis and sacroiliitis correlate with greater pain intensity and poor quality-of-life measures. Tumor necrosis factor inhibitors are the mainstay of biologic therapy. Although other biologics such as IL-17 blockers have shown benefit in adult spondyloarthritis, none are approved by the US Food and Drug Administration.

The TNF-NF-kB-DKK1 Axis Promoted Bone Formation in the Enthesis of Ankylosing Spondylitis

Objective

This study aimed to determine the serum Dickkopf 1 (DKK1) levels in ankylosing spondylitis (AS) patients and decipher the mechanism of tumor necrosis factor (TNF)-mediated DKK1 regulation in human AS enthesis cells.

Methods

The sera were obtained from 103 patients with AS and 30 healthy controls (HCs) The enthesis of facet joints were obtained from 4 AS patients and 5 controls The serum levels of DKK1 were measured using ELISA and compared between AS and HCs The impact of TNF on DKK1 expression in human primary spinal enthesis cells was evaluated using various molecular biology techniques and bone formation indicators.

Results

AS patients showed higher serum DKK1 levels than HCs after adjusting for age (9174 [6153∼1,3100] pg/mL vs 8262 [6703∼9278] pg/mL, p=0043) TNF treatment promoted bone formation and DKK1 expression in both control enthesis cells and those of AS This enhanced bone formation by TNF was pronounced in AS-enthesis than those of controls Mechanically, TNF induced NF-kB activation upregulates the DKK1 transcript level While, NF-kB inhibitor led to downregulate DKK1 expression in the enthesis Besides, DKK1 overexpression promoted bone formation in enthesis.

Conclusion

TNF induced DKK1 expression in the enthesis through NF-kB activation TNF-induced DKK1 expression may play a bone formation in the radiologic progression of ankylosing spondylitis.

The synergistic role of TNFA - 308G/A and IL10 - 1082A/G polymorphisms in ankylosing spondylitis

OBJECTIVE

Genetic polymorphisms of the cytokine genes could alter their protein expression, thus creating a genetic basis of dysregulated cytokine production and function, which render them as excellent candidates predisposing to autoimmune diseases. We investigated single nucleotide polymorphisms (SNPs) at TNFA - 308G/A and IL10 - 1082A/G locus to identify their involvement, separately or in combination, in determining susceptibility to ankylosing spondylitis (AS), as well as their functional connections with relevant serum cytokines and associations with disease characteristics.

METHODS

Eighty-one AS patients and 215 healthy controls were genotyped by polymerase chain reaction-based method; 76 patients and sex-matched controls were also subjected to analysis of serum TNF-α and IL-10 levels by enzyme-linked immunosorbent assay.

RESULTS

We identified the homozygous genotype GG of the TNFA-308 significantly more common in patients than controls; whereas the - 308 minor A-allele predicts a threefold decreased risk against developing AS and shows associations with milder radiographic spinal impairments and functional limitations. This protective effect was multiplied by fivefold in synergistic interaction with the homozygous - 1082AA genotype of the IL10 which acts as a modifying factor, since IL10 - 1082A/G SNPs by itself did not have a significant impact on AS genetic susceptibility. In comparison with controls, AS patients had significantly elevated mean serum TNF-α levels and decreased mean IL-10 concentrations not restricted to any particular genotype.

CONCLUSION

TNFA - 308 A-allele is essential for reducing susceptibility to AS, with a considerable synergistic protective effect of the combined TNF-α - 308 (GA/AA)/IL-10 - 1082AA genotypes. In addition, the presence of this variant allele is associated with more benign clinical phenotype of the disease. No conclusive statements on the functional relevance of both gene variants on cytokines production should be made.

Complexity of enthesitis and new bone formation in ankylosing spondylitis: current understanding of the immunopathology and therapeutic approaches

Despite increasing availability of treatments for spondyloarthritis (SpA) including tumour necrosis factor (TNF) and interleukin-17 (IL-17) inhibitors, there is no established treatment that abates new bone formation (NBF) in ankylosing spondylitis (AS), a subset of SpA. Recent research on TNF has revealed the increased level of transmembrane TNF in the joint tissue of SpA patients compared to that of rheumatoid arthritis patients, which appears to facilitate TNF-driven osteo-proliferative changes in AS. In addition, there is considerable interest in the central role of IL-23/IL-17 axis in type 3 immunity and the therapeutic potential of blocking this axis to ameliorate enthesitis and NBF in AS. AS immunopathology involves a variety of immune cells, including both innate and adoptive immune cells, to orchestrate the immune response driving type 3 immunity. In response to external stimuli of inflammatory cytokines, local osteo-chondral progenitor cells activate intra-cellular anabolic molecules and signals involving hedgehog, bone morphogenetic proteins, receptor activator of nuclear factor kappa-B ligand, and Wnt pathways to promote NBF in AS. Here, we provide an overview of the current immunopathology and future directions for the treatment of enthesitis and NBF associated with AS.

Ankylosing spondylitis: an autoimmune or autoinflammatory disease?

Ankylosing spondylitis (AS) is a chronic inflammatory disorder of unknown aetiology. Unlike other systemic autoimmune diseases, in AS, the innate immune system has a dominant role characterized by aberrant activity of innate and innate-like immune cells, including γδ T cells, group 3 innate lymphoid cells, neutrophils, mucosal-associated invariant T cells and mast cells, at sites predisposed to the disease. The intestine is involved in disease manifestations, as it is at the forefront of the interaction between the mucosal-associated immune cells and the intestinal microbiota. Similarly, biomechanical factors, such as entheseal micro-trauma, might also be involved in the pathogenesis of the articular manifestation of AS, and sentinel immune cells located in the entheses could provide links between local damage, genetic predisposition and the development of chronic inflammation. Although these elements might support the autoinflammatory nature of AS, studies demonstrating the presence of autoantibodies (such as anti-CD74, anti-sclerostin and anti-noggin antibodies) and evidence of activation and clonal expansion of T cell populations support an autoimmune component to the disease. This Review presents the evidence for autoinflammation and the evidence for autoimmunity in AS and, by discussing the pathophysiological factors associated with each, aims to reconcile the two hypotheses.

Vascular Endothelial Growth Factor Biology and Its Potential as a Therapeutic Target in Rheumatic Diseases

Rheumatic diseases constitute a diversified group of diseases distinguished by arthritis and often involve other organs. The affected individual has low quality of life, productivity even life-threatening in some severe conditions. Moreover, they impose significant economic and social burdens. In recent years, the patient outcome has been improved significantly due to clearer comprehension of the pathology of rheumatic diseases and the effectiveness of "treat to target" therapies. However, the high cost and the adverse effects are the concerns and full remissions are not often observed. One of the main processes that contributes to the pathogenesis of rheumatic diseases is angiogenesis. Vascular endothelial growth factor (VEGF), a central mediator that regulates angiogenesis, has different isoforms and functions in various physiological processes. Increasing evidence suggests an association between the VEGF system and rheumatic diseases. Anti-VEGF and VEGF receptor (VEGFR) therapies have been used to treat several cancers and eye diseases. This review summarizes the current understanding of VEGF biology and its role in the context of rheumatic diseases, the contribution of VEGF bioavailability in the pathogenesis of rheumatic diseases, and the potential implications of therapeutic approaches targeting VEGF for these diseases.

Direct anti-proliferative effect of adipose-derived mesenchymal stem cells of ankylosing spondylitis patients on allogenic CD4+ cells

Objectives

T-cell-mediated adaptive immunity contributes to the development and persistence of ankylosing spondylitis (AS). Mesenchymal stromal/stem cells (MSCs) have immunomodulatory potential and are able to inhibit T-cell proliferation, but their functionality in AS patients is relatively unknown. The aim of the study was to assess the direct anti-proliferative effects of MSCs isolated from subcutaneous abdominal adipose tissue of AS patients (AS/ASCs) on allogeneic T lymphocytes, using commercially available ASC lines from healthy donors (HD/ASCs) as a control.

Material and methods

CD3+CD4+ T-cells were isolated from peripheral blood of healthy blood donors, activated with anti-CD3/CD28 beads, and co-cultured for 5 days with untreated and TNF+IFN-γ pre-stimulated HD/ASCs (5 cell lines) and AS/ASCs, obtained from 11 patients (6F/5M). The proliferative response of T-cells was analysed by flow cytometry, while the concentrations of kynurenines, prostaglandin E2 (PGE-2), interleukin 10 (IL-10), and interleukin 1 receptor antagonist (IL-1Ra) were measured spectrophotometrically or using a specific enzyme-linked immunosorbent assay (ELISA).

Results

HD/ASCs and AS/ASCs similarly reduced the T-cell proliferation response, i.e. the percentage of proliferating cells, the proliferation, and replication indices, and these effects were dependent mostly on soluble factors. In the co-cultures of activated CD4+ T-cells with HD/ASCs and AS/ASCs significant increases of kynurenines, PGE-2, and IL-1Ra, but not IL-10, production were observed. The release of these factors was dependent either on cell-to-cell contact (IL-10, IL-1Ra) or soluble factors (kynurenines, PGE-2). There was a moderate to strong negative correlation between T-cell proliferative response, and the concentrations of kynurenines, PGE-2, and IL-10, but not IL-1Ra. This association was more evident in the case of TI-treated AS/ASCs than HD/ASCs.

Conclusions

AS/ASCs, similar to HD/ASCs, exert a direct effective anti-proliferative impact on CD4+ T cells, acting via soluble factors that are released in cell contact-dependent (IL-10) and independent (kynurenines, PGE-2) pathways. Thus, our results suggest that AS/ASCs are potentially useful for therapeutic application.

Inhibition of Allogeneic and Autologous T Cell Proliferation by Adipose-Derived Mesenchymal Stem Cells of Ankylosing Spondylitis Patients

Background

In ankylosing spondylitis (AS), accompanied by chronic inflammation, T cell expansion plays a pathogenic role; the immunoregulatory properties of bone marrow-derived mesenchymal stem cells (BM-MSCs) are impaired, while functional characteristics of their adipose tissue-derived counterparts are (ASCs) unknown.

Methods

We evaluated the antiproliferative activity of AS/ASCs, obtained from 20 patients, towards allogeneic and autologous T lymphocytes, using ASCs from healthy donors (HD/ASCs) as the reference cell lines. The PHA-activated peripheral blood mononuclear cells (PBMCs) were cocultured in cell-cell contact and transwell conditions with untreated or TNF + IFNγ- (TI-) licensed ASCs, then analyzed by flow cytometry to identify proliferating and nonproliferating CD4⁺ and CD8⁺ T cells. The concentrations of kynurenines, prostaglandin E₂ (PGE₂), and IL-10 were measured in culture supernatants.

Results

In an allogeneic system, HD/ASCs and AS/ASCs similarly decreased the proliferation of CD4⁺ and CD8⁺ T cells and acted mainly via soluble factors. The concentrations of kynurenines and PGE₂ inversely correlated with T cell proliferation, and selective inhibitors of these factors synthesis significantly restored T cell response. AS/ASCs exerted a similar antiproliferative impact also on autologous T cells.

Conclusion

We report for the first time that despite chronic in vivo exposure to inflammatory conditions, AS/ASCs retain the normal capability to restrain expansion of allogeneic and autologous CD4⁺ and CD8⁺ T cells, act primarily via kynurenines and PGE₂, and thus may have potential therapeutic value. Some distinctions between the antiproliferative effects of AS/ASCs and HD/ASCs suggest in vivo licensing of AS/ASCs.

Safety and Efficacy of Prefilled Liquid Etanercept-Biosimilar Yisaipu for Active Ankylosing Spondylitis: A Multi-Center Phase III Trial

Introduction

The aim of this work is to examine the efficacy and safety of prefilled liquid etanercept-biosimilar Yisaipu versus lyophilized Yisaipu in active ankylosing spondylitis (AS) patients.

Methods

This double-blind, phase III trial with non-inferiority design randomized adult patients with active AS in a 3:1:1 ratio to receive twice-weekly 25-mg prefilled liquid Yisaipu for a total of 48 injections (group I, n = 330), once-weekly 50-mg prefilled liquid Yisaipu for 24 injections (group II, n = 110), or twice-weekly 25-mg lyophilized Yisaipu for 48 injections (group III, n = 110). Both physicians and patients who received 25-mg twice-weekly lyophilized or liquid Yisaipu were blinded to treatment assignment while patients who received 50-mg once-weekly liquid Yisaipu received treatment in an open-label design. In addition, 90 patients in the PK/PD study were randomized in a 1:1:1 ratio to each group. The primary outcome was the proportion of patients who achieved ASAS20 at week 24.

Results

A total of 640 subjects were enrolled. The proportion of patients who attained ASAS20 at week 24 was 85.56% in group I, 85.71% in group II, and 83.45% in group III (group I vs. III, P = 0.545; group II vs. III, P = 0.605). The difference between group I and III was 2.10% (95% CI − 5.06%, 9.27%) and 2.26% (95% CI − 6.21%, 10.73%) between group II and III, meeting the non-inferiority threshold (Δ = − 15%) (P < 0.001). Except for a statistical difference between group I (75.83%) and group III at week 8 (64.75%, P = 0.011), there was no statistical difference in the ASAS20 attainment rate among the three groups at other time points. The incidence of serious adverse events was comparable among the three groups (group I, 2.50%, II, 2.86% and III, 1.43%; P > 0.05). No deaths were reported.

Conclusions

Once-weekly 50-mg or twice-weekly 25-mg prefilled liquid Yisaipu is safe and non-inferior to twice-weekly 25-mg lyophilized Yisaipu.

Trial Registration

CTR20130124 and NCT04345458.

Supplementary Information

The online version contains supplementary material available at 10.1007/s40744-021-00276-1.