Why did IL-23p19 inhibition fail in AS: a tale of tissues, trials or translation?

Smoking in spondyloarthritis: unravelling the complexities

Tobacco smoking is a major threat to health. There is no doubt about the need to promote and support cessation at every opportunity. Smoking has a clear role in RA, but what evidence is there that the same relationship exists in SpA? In this review, we examine (the less cited) paradoxes and contradictions in the existing axial SpA (axSpA) and PsA literature; for example, smoking appears to be 'protective' for some axSpA manifestations. We also highlight findings from higher quality evidence: smoking is associated with increased risk of PsA and the risk of psoriasis in axSpA. The relationship between smoking and SpA is far from simple. Our aim is to highlight the harms of smoking in SpA and bring attention to inconsistencies in the literature to inform further research.

BSR Spondyloarthritis Course, 27 February 2020. Spondyloarthritis: pathogenesis, diagnosis and management

High-quality continuous medical education is essential to maintain excellence in health-care delivery, upskilling professionals and improving patient outcomes. This is particularly relevant when addressing rare disease groups, such as the spondyloarthritides, a group of heterogeneous inflammatory conditions that affect joints and other organs, such as the skin, bowel and eye. Professional bodies, such as the British Society for Rheumatology (BSR), are well placed to deliver this type of education. In 2020, the BSR ran a dedicated SpA course aimed at rheumatology health-care professionals wishing to update their basic knowledge of SpA with a review of the latest advances in the field. Here, we summarize the proceedings of the meeting and discuss the value of such an initiative.

New developments in our understanding of ankylosing spondylitis pathogenesis

Ankylosing spondylitis (AS) is a common immune‐mediated inflammatory arthritis with a strong genetic predisposition. We review recent data from genetic and animal studies highlighting the importance of Type 17 immune responses. Furthermore, the efficacy (or lack thereof) of different anti‐cytokine monoclonal antibodies has highlighted the diversity of Type 17 immune cells and cytokines critical to AS and related spondyloarthritis pathogenesis. Recent studies have strongly implicated the gut microbiome in AS. Finally, we propose that the local metabolic environment of the joint may have a key role in driving AS, and present a novel model of AS pathogenesis.

Tackling the autoimmune side in Spondyloarthritis: A systematic review

Spondyloarthritis (SpA) are a heterogeneous group of inflammatory chronic diseases characterized by sharing common pathogenic, clinical and radiologic features. The aim of this review is to support clinicians in understanding and managing this complex disease, from pathogenesis to therapeutic targets, through a systematic review of the current literature in accordance with PRISMA guidelines and checklist. HLA-B27 has been found to be associated with axial involvement either in SA and in PsA patients: it might be involved through presentation of an "arthritogenic peptide" to autoreactive CD8+ T cells or might accumulate in misfolded form and induce production pro-inflammatory cytokines by binding to several innate immune receptors. This genetic background in combination with mechanical stress leads to the activation of both innate and acquired immune responses as well as a possible role of autoimmunity in SpA pathogenesis. The release of IL-23 and IL-17 is relevant for their systemic and local effect on bone, inducing the activation of osteoclasts. Thus, the regulatory role of IL-17 on fibroblasts, osteoblasts and chondrocytes has an impact in both synovial inflammation and joint destruction. Innovative therapies targeting IL-12/23 and IL-17 and the use of small targeted synthetic molecules, as JAK-inhibitors, proved to be effective in SpA patients representing an alternative strategy to TNF-inhibitors.

Revisiting the gut-joint axis: links between gut inflammation and spondyloarthritis

Gut inflammation is strongly associated with spondyloarthritis (SpA), as exemplified by the high prevalence of inflammatory bowel disease (IBD) and the even higher occurrence of subclinical gut inflammation in patients with SpA. The gut-joint axis of inflammation in SpA is further reinforced by similarities in immunopathogenesis at both anatomical sites and by the clinical success of therapies blocking TNF and IL-23 in IBD and in some forms of SpA. Many genetic risk factors are shared between SpA and IBD, and changes in the composition of gut microbiota are seen in both diseases. Current dogma is that inflammation in SpA initiates in the gut and leads to joint inflammation; however, although conceptually attractive, some research does not support this causal relationship. For example, therapies targeting IL-17A are efficacious in the joint but not the gut, and interfering with gut trafficking by targeting molecules such as α4β7 in IBD can lead to onset or flares of SpA. Several important knowledge gaps remain that must be addressed in future studies. Determining the true nature of the gut-joint axis has real-world implications for the treatment of patients with co-incident IBD and SpA and for the repurposing of therapeutics from one disease to the other.

Recent advances in managing axial spondyloarthritis

Axial spondyloarthritis (axSpA) is a chronic inflammatory rheumatic disease that predominantly affects the axial skeleton. The advent of biologic drugs has transformed the management of patients with axSpA. However, non-steroidal anti-inflammatory drugs remain the first-line drug treatment for axSpA. The optimal management of patients with axSpA requires a combination of pharmacological and non-pharmacological treatment modalities, namely exercise and physical therapy. This review looks at novel therapeutic options in patients with axSpA. It also summarises current evidence regarding radiographic progression and treat-to-target in axSpA.

EULAR recommendations for the management of psoriatic arthritis with pharmacological therapies: 2019 update

OBJECTIVE

To update the European League Against Rheumatism (EULAR) recommendations for the pharmacological treatment of psoriatic arthritis (PsA).

METHODS

According to the EULAR standardised operating procedures, a systematic literature review was followed by a consensus meeting to develop this update involving 28 international taskforce members in May 2019. Levels of evidence and strengths of recommendations were determined.

RESULTS

The updated recommendations comprise 6 overarching principles and 12 recommendations. The overarching principles address the nature of PsA and diversity of both musculoskeletal and non-musculoskeletal manifestations; the need for collaborative management and shared decision-making is highlighted. The recommendations provide a treatment strategy for pharmacological therapies. Non-steroidal anti-inflammatory drugs and local glucocorticoid injections are proposed as initial therapy; for patients with arthritis and poor prognostic factors, such as polyarthritis or monoarthritis/oligoarthritis accompanied by factors such as dactylitis or joint damage, rapid initiation of conventional synthetic disease-modifying antirheumatic drugs is recommended. If the treatment target is not achieved with this strategy, a biological disease-modifying antirheumatic drugs (bDMARDs) targeting tumour necrosis factor (TNF), interleukin (IL)-17A or IL-12/23 should be initiated, taking into account skin involvement if relevant. If axial disease predominates, a TNF inhibitor or IL-17A inhibitor should be started as first-line disease-modifying antirheumatic drug. Use of Janus kinase inhibitors is addressed primarily after bDMARD failure. Phosphodiesterase-4 inhibition is proposed for patients in whom these other drugs are inappropriate, generally in the context of mild disease. Drug switches and tapering in sustained remission are addressed.

CONCLUSION

These recommendations provide stakeholders with an updated consensus on the pharmacological management of PsA, based on a combination of evidence and expert opinion.

Normal human enthesis harbours conventional CD4+ and CD8+ T cells with regulatory features and inducible IL-17A and TNF expression

Background

The human enthesis conventional T cells are poorly characterised.

Objectives

To study the biology of the conventional T cells in human enthesis.

Methods

CD4+ and CD8+ T cells were investigated in 25 enthesis samples using immunofluorescence, cytometrically, bulk RNAseq and quantitative real-time PCR following anti-CD3/CD28 bead stimulation to determine interleukin (IL)-17A and tumour necrosis factor (TNF) levels. T-cell receptor (TCR) repertoires were characterised and a search for putative T-cell reactivity was carried out using TCR3 database. The impact of pharmacological antagonism with retinoic acid receptor-related orphan nuclear receptor gamma t inhibitor (RORγti), methotrexate and phosphodiesterase type 4 inhibitor (PDE4i) was investigated.

Results

Immunofluorescence and cytometry suggested entheseal resident CD4+ and CD8+ T cells with a resident memory phenotype (CD69+/CD45RA-) and tissue residency gene transcripts (higher NR4A1/AhR and lower KLF2/T-bet transcripts). Both CD4+ and CD8+ T cells showed increased expression of immunomodulatory genes including IL-10 and TGF-β compared with peripheral blood T cells with entheseal CD8+ T cells having higher CD103, CD49a and lower SIPR1 transcript that matched CD4+ T cells. Following stimulation, CD4+ T cells produced more TNF than CD8+ T cells and IL-17A was produced exclusively by CD4+ T cells. RNAseq suggested both Cytomegalovirus and influenza A virus entheseal resident T-cell clonotype reactivity. TNF and IL-17A production from CD4+ T cells was effectively inhibited by PDE4i, while RORγti only reduced IL-17A secretion.

Conclusions

Healthy human entheseal CD4+ and CD8+ T cells exhibit regulatory characteristics and are predicted to exhibit antiviral reactivity with CD8+ T cells expressing higher levels of transcripts suggestive of tissue residency. Inducible IL-17A and TNF production can be robustly inhibited in vitro.

Interleukin-23 pathway at the enthesis: The emerging story of enthesitis in spondyloarthropathy

The inflammatory disorders collectively termed the seronegative spondyloarthropathies (SpA) include ankylosing spondylitis (AS), psoriatic arthritis (PsA), reactive arthritis, the arthritis associated with inflammatory bowel disease including Crohn's disease and ulcerative colitis, the arthritis related to anterior uveitis, and finally, somewhat controversially Behcet's disease. All of these diseases are associated with SNPs in the IL-23R or the interleukin-23 (IL-23) cytokine itself and related downstream signaling JAK pathway genes and the interleukin-17 (IL-17) pathway. In rheumatoid arthritis, the target of the immune response is the synovium but the SpA disorders target the tendon, ligament, and joint capsule skeletal anchorage points that are termed entheses. The discovery that IL-23R-expressing cells were ensconced in healthy murine enthesis, and other extraskeletal anchorage points including the aortic root and the ciliary body of the eye and that systemic overexpression of IL-23 resulted in a severe experimental SpA, confirmed a fundamentally different immunobiology to rheumatoid arthritis. Recently, IL-23R-expressing myeloid cells and various innate and adaptive T cells that produce IL-17 family cytokines have also been described in the human enthesis. Blockade of IL-23 pathway with either anti-p40 or anti-p19 subunits has resulted in some spectacular therapeutic successes in psoriasis and PsA including improvement in enthesitis in the peripheral skeleton but has failed to demonstrate efficacy in AS that is largely a spinal polyenthesitis. Herein, we discuss the known biology of IL-23 at the human enthesis and highlight the remarkable emerging story of this unique skeletal tissue.

Molecular control of pathogenic Th17 cells in autoimmune diseases

IL-17A-producing CD4⁺ T helper cells (Th17) are crucial for the development of inflammatory and autoimmune diseases and thus are exploited for clinical immunotherapies. Emerging evidence suggests Th17 cells are heterogeneous and able to adopt both pathogenic and non-pathogenic phenotypes which are shaped by environmental and genetic factors. On one hand, IL-6 in concert with TGFβ1 can induce non-pathogenic Th17 cells (non-pTh17), which are not effective in inducing tissue inflammation. On the other hand, IL-6, IL-1β with IL-23 induce pathogenic Th17 cells (pTh17) to induce immune pathologies in various tissues. Th17 cells could be both pathogenic and non-pathogenic in a content-dependent manner in vivo. Understanding how the generation and pathogenicity of pTh17 cells are regulated will aid us to devise more effective immunotherapy. In this review, we summarize recent advances in the differentiation and regulation of Th17 cells especially pTh17 cells in vitro and in vivo. The emerging results revealing the specific molecular control of pTh17 cells are highlighted.

Unmet need in rheumatology: reports from the Targeted Therapies meeting 2019

Objectives

To detail the greatest areas of unmet scientific and clinical needs in rheumatology.

Methods

The 21st annual international Advances in Targeted Therapies meeting brought together more than 100 leading basic scientists and clinical researchers in rheumatology, immunology, epidemiology, molecular biology and other specialties. During the meeting, breakout sessions were convened, consisting of 5 disease-specific groups with 20–30 experts assigned to each group based on expertise. Specific groups included: rheumatoid arthritis, psoriatic arthritis, axial spondyloarthritis, systemic lupus erythematosus and other systemic autoimmune rheumatic diseases. In each group, experts were asked to identify unmet clinical and translational research needs in general and then to prioritise and detail the most important specific needs within each disease area.

Results

Overarching themes across all disease states included the need to innovate clinical trial design with emphasis on studying patients with refractory disease, the development of trials that take into account disease endotypes and patients with overlapping inflammatory diseases, the need to better understand the prevalence and incidence of inflammatory diseases in developing regions of the world and ultimately to develop therapies that can cure inflammatory autoimmune diseases.

Conclusions

Unmet needs for new therapies and trial designs, particularly for those with treatment refractory disease, remain a top priority in rheumatology.

The IL-23-IL-17 pathway as a therapeutic target in axial spondyloarthritis

The cytokines IL-23 and IL-17 have an important role in the pathogenesis of, and as a therapeutic target in, both animal models of chronic inflammation and some human chronic inflammatory diseases. The traditional view is that a main source of IL-17 is T cells and that IL-17 production is under the control of IL-23. IL-17 inhibition has shown good efficacy in clinical trials for ankylosing spondylitis (AS), a subtype of axial spondyloarthritis (axSpA) characterized by radiographic evidence of sacroiliitis. On the basis of data from animal models, genetic studies and the investigation of tissue and blood samples from patients with AS, IL-23 had also been predicted to be important in the pathogenesis of this disease and was therefore considered a potential therapeutic target for axSpA. However, two placebo-controlled, double-blind clinical trials in axSpA of monoclonal antibodies directed against either the p40 protein or the p19 protein of the IL-23 molecule had clear negative results. These findings indicate that IL-23 and IL-17 are at least partly uncoupled in axSpA. Reasons as to why, when and how such an uncoupling might occur are discussed in this Review, with special reference to the unique microenvironment of the subchondral bone marrow in axSpA.

Precision medicine in psoriatic arthritis: how should we select targeted therapies?

Psoriatic arthritis (PsA) is a heterogeneous inflammatory arthritis associated with psoriasis. Patients manifest variable presentations with potential involvement of peripheral joints, spine, tendons, skin, and nails. There has been a rapid expansion in targeted treatment options for patients with PsA, but typically less than half of those who receive therapy achieve optimal treatment targets. Many patients respond to second-line or third-line biological therapies, but little evidence exists to guide the choice of therapeutics for each individual. At present, choice of therapy is driven by active clinical disease domains, clinician familiarity with existing treatments, and cost. Here, we review recent data that highlight the potential for personalised, or precision, medicine in PsA and other forms of inflammatory arthritis, noting that this research is still at a preliminary stage. In the future, a combination of detailed immunophenotyping and sophisticated statistical analyses should help to facilitate a personalised medicine approach in PsA, following examples from other clinical areas, such as oncology. This change in approach to the treatment of PsA has the potential to maximise outcomes for patients and to provide optimal therapies without delay.

Ankylosing spondylitis: etiology, pathogenesis, and treatments

Ankylosing spondylitis (AS), a common type of spondyloarthropathy, is a chronic inflammatory autoimmune disease that mainly affects spine joints, causing severe, chronic pain; additionally, in more advanced cases, it can cause spine fusion. Significant progress in its pathophysiology and treatment has been achieved in the last decade. Immune cells and innate cytokines have been suggested to be crucial in the pathogenesis of AS, especially human leukocyte antigen (HLA)‑B27 and the interleukin‑23/17 axis. However, the pathogenesis of AS remains unclear. The current study reviewed the etiology and pathogenesis of AS, including genome-wide association studies and cytokine pathways. This study also summarized the current pharmaceutical and surgical treatment with a discussion of future potential therapies.

Non-Radiographic Axial Spondyloarthritis (nr-axSpA): Advances in Classification, Imaging and Therapy

Non-radiographic axial spondyloarthritis (nr-axSpA) is a recently described form of axial inflammatory arthritis that has not caused substantial erosive damage to the sacroiliac joints. Nr-axSpA is associated with significant impairment in quality of life and, in a proportion of patients, it can evolve into ankylosing spondylitis (AS, also termed radiographic axSpA). The identification in the clinic of nr-axSpA has been made possible by advances in magnetic resonance imaging (MRI). Classification criteria for nr-axSpA have been proposed but there remains discussion in the international community regarding this. Studies are ongoing to further define the classification and diagnosis of nr-axSpA. There is much further research required regarding the optimal use of MRI in nr-axSpA, including distinguishing sacroiliac MRI changes in the normal population and the definition of a positive MRI in spinal disease. Non-steroidal anti-inflammatory drugs and physiotherapy are the core first-line therapy for nr-axSpA. Tumour necrosis factor inhibitors also play a very important role in treatment of patients with active nr-axSpA who do not respond to first-line therapy. Agents directed at interleukin-17, interleukin-23 and Janus kinase inhibitors are proving effective in AS with ongoing and planned studies in nr-axSpA. A great deal of active research is being undertaken in classification, imaging and therapy in nr-axSpA and so the future for improving the lives of patients with nr-axSpA is promising.

Inflammatory bowel diseases and spondyloarthropathies: From pathogenesis to treatment

Spondyloarthropathies (SpA) include many different forms of inflammatory arthritis and can affect the spine (axial SpA) and/or peripheral joints (peripheral SpA) with Ankylosing spondylitis (AS) being the prototype of the former. Extra-articular manifestations, like uveitis, psoriasis and inflammatory bowel disease (IBD) are frequently observed in the setting of SpA and are, in fact, part of the SpA classification criteria. Bowel involvement seems to be the most common of these manifestations. Clinically evident IBD is observed in 6%-14% of AS patients, which is significantly more frequent compared to the general population. Besides, it seems that silent microscopic gut inflammation, is evident in around 60% in AS patients. Interestingly, occurrence of IBD has been associated with AS disease activity. For peripheral SpA, two different forms have been proposed with diverse characteristics. Of note, SpA (axial or peripheral) is more commonly observed in Crohn's disease than in ulcerative colitis. The common pathogenetic mechanisms that explain the link between IBD and SpA are still ill-defined. The role of dysregulated microbiome along with migration of T lymphocytes and other cells from gut to the joint ("gut-joint" axis) has been recognized, in the context of a genetic background including associations with alleles inside or outside the human leukocyte antigen system. Various therapeutic modalities are available with monoclonal antibodies against tumour necrosis factor, interleukin-23 and interleukin-17, being the most effective. Both gastroenterologists and rheumatologists should be alert to identify the co-existence of these conditions and ideally follow-up these patients in combined clinics.

Identification of myeloid cells in the human enthesis as the main source of local IL-23 production

OBJECTIVE

We investigated whether the normal human spinal enthesis contained resident myeloid cell populations, capable of producing pivotal proinflammatory cytokines including tumour necrosis factor (TNF) and interleukin (IL)-23 and determined whether these could be modified by PDE4 inhibition.

METHODS

Normal human enthesis soft tissue (ST) and adjacent perientheseal bone (PEB) (n=15) were evaluated using immunohistochemistry (IHC), digested for myeloid cell phenotyping, sorted and stimulated with different adjuvants (lipopolysaccharide and mannan). Stimulated enthesis fractions were analysed for inducible production of spondyloarthropathy disease-relevant mediators (IL-23 full protein, TNF, IL-1β and CCL20). Myeloid populations were also compared with matched blood populations for further mRNA analysis and the effect of PDE4 inhibition was assessed.

RESULTS

A myeloid cell population (CD45+ HLADR+ CD14+ CD11c+) phenotype was isolated from both the ST and adjacent PEB and termed 'CD14+ myeloid cells' with tissue localisation confirmed by CD14+ IHC. The CD14- fraction contained a CD123+ HLADR+ CD11c- cell population (plasmacytoid dendritic cells). The CD14+ population was the dominant entheseal producer of IL-23, IL-1β, TNF and CCL20. IL-23 and TNF from the CD14+ population could be downregulated by a PDE4I and other agents (histamine and 8-Bromo-cAMP) which elevate cAMP. Entheseal CD14+ cells had a broadly similar gene expression profile to the corresponding CD14+ population from matched blood but showed significantly lower CCR2 gene expression.

CONCLUSIONS

The human enthesis contains a CD14+ myeloid population that produces most of the inducible IL-23, IL-1β, TNF and CCL20. This population has similar gene expression profile to the matched blood CD14+ population.