Vertebral erosions associated with spinal inflammation in patients with ankylosing spondylitis identified by magnetic resonance imaging: changes after 2 years of tumor necrosis factor inhibitor therapy

Significance of structural changes in the axial skeleton in patients with axial spondyloarthritis: how important are lesions in the sacroiliac joint?

Inflammatory back pain (IBP) is a characteristic clinical symptom of patients with axial spondyloarthritis (axSpA) that is caused by inflammation in the axial skeleton. In early disease stages the sacroiliac joints (SIJ) are most often affected, the spine usually at later stages. In many but clearly not all cases of axSpA new bone formation in form of syndesmophytes and ankylosis occur in the further course of the disease. Function and mobility may be impaired by both, inflammation and structural changes. In clinical trials outcome parameters most often used refer to pain, disease activity, function, mobility and global health but many researchers are also interested in radiographic progression in the axial skeleton of patients with axSpA. This viewpoint discusses the relevance of structural changes in the SIJ in comparison to the spine and in relation to functional outcomes and mobility.

[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.

The value of MRI compared to conventional radiography in analysing morphologic changes in the spine in axial spondyloarthritis

Background

Imaging of morphologic changes in the vertebral spine in axial spondyloarthritis (SpA) is routinely performed with conventional radiography limited by superposition in the thoracic segments and radiation exposure. The objective was to assess the reliability of MRI compared to conventional radiography in depicting morphologic vertebral lesions in patients with axial SpA. Forty patients diagnosed with axial SpA were included in this cross-sectional study. Patients underwent MRI of the whole spine with T1-weighted and TIRM sequences in the sagittal plane and conventional radiography of the cervical and lumbar spine in lateral projections. Morphologic changes (syndesmophytes and erosions) in the anterior vertebral endplates on MRI and conventional radiography were independently evaluated by two radiologists. Inter-modality and interobserver agreement were calculated using Cohen’s Kappa.

Results

Inter-modality agreement was low for cervical and lumbar syndesmophytes and erosions (κ ≤ 0.2 ± 0.07–0.1). Interobserver agreement on conventional radiography was highest for cervical and lumbar anterior syndesmophytes/bridging (κ = 0.92 ± 0.02–0.03). Syndesmophytes in thoracic anterior vertebral units were the most frequent MRI finding with a high interobserver agreement (κ = 0.83 ± 0.05).

Conclusions

In imaging morphologic changes in the spine in patients with axial SpA, MRI was shown to be not an equivalent substitute but a complementary imaging modality to conventional radiography. Conventional radiography seems superior to depict morphologic cervical and lumbar vertebral changes compared to MRI, whereas MRI may visualise morphologic lesions in the thoracic spine.

Significance of structural changes in the sacroiliac joints of patients with axial spondyloarthritis detected by MRI related to patients symptoms and functioning

Axial spondyloarthritis (axSpA) is a chronic inflammatory rheumatic disease that manifests primarily in the axial skeleton, initially mostly in the sacroiliac joints (SIJ), usually later spreading to the spine. The disease is characterised by inflammation and new bone formation which are mainly assessed by conventional radiography (CR) and magnetic resonance imaging (MRI). Tumour necrosis factor inhibitors (TNFi) and interleukin-17 antagonists have been shown to be efficacious and efficient in patients with axSpA. This treatment seems to also inhibit structural damage, for example, retard radiographic progression. Indeed, a reduction of new bone formation in the spine, as assessed by CR, has been reported to occur after at least 2 years of therapy with TNFi. Recently, a reduction of erosions and ankylosis in the SIJ has also been observed in axSpA patients treated with etanercept and filgotinib. In this narrative review, we discuss the limited significance of such findings.

Imaging Scoring Methods in Axial Spondyloarthritis

Inflammatory and chronic structural changes are objective signs of axial spondyloarthritis. In the sacroiliac joints (SIJs), inflammation (sacroiliitis) can be visualized as bone marrow edema, whereas chronic structural changes are visualized as fat metaplasia, erosions, sclerosis, or ankylosis in the area of the SIJ. In the spine, bone marrow edema in the vertebral bodies represents spondylitis but can also affect the facet and the costovertebral and costotransverse joints (arthritis), whereas structural changes are visualized as fat metaplasia, sclerosis or syndesmophytes and ankylosis at the vertebral edges.

[Inflammatory spinal diseases: axial spondyloarthritis : Central importance of imaging]

The diagnosis of axial spondyloarthritis (axSpA) includes classical ankylosing spondylitis (AS) as well as earlier stages and abortive courses of the disease, in which structural alterations have not yet occurred. These are classified as non-radiographic axSpA (nr-axSpa). Inflammatory changes in the entire axial skeleton are characteristic for axSpA and can be visualized by magnetic resonance imaging (MRI), while in most patients structural alterations, such as new bone formation with syndesmophytes and ankylosis develop in the later course of the disease. These bony alterations can best be visualized by conventional radiography and by computed tomography. Certain MRI sequences are nowadays considered as the standard method for depiction of inflammatory changes in axSpA. The introduction of MRI has led to a paradigm shift for this disease because the inflammatory lesions characteristic for the disease can be visualized at an early stage using appropriate MRI sequences.

Non-invasive imaging demonstrates clinical features of ankylosing spondylitis in a rat adjuvant model: a case study

Main features of ankylosing spondylitis like inflammatory erosive osteopenia and bony overgrowth are recapitulated in rats challenged with complete Freund’s adjuvant. In vivo changes induced in the rat spine were followed longitudinally by magnetic resonance imaging (MRI) and assessed terminally by micro-computerized tomography (micro-CT) and histology. Signals reflecting inflammation were detected by MRI at levels L5-L6 throughout the experiment, peaking at day 27 after adjuvant. Bone erosion and formation occurred from this time point onward, as confirmed by micro-CT. Histology confirmed the inflammation and bone remodeling. The present study demonstrates the potential of imaging for longitudinal assessments of spinal changes in this animal model and the excellent correlation between in vivo images and histology underlines its fundamental role in the validation of non-invasive imaging.

Assessment of spinal pain

Spinal pain or back pain is a very common symptom that can have many reasons. The most studied location is low back pain, and it is considered to be nonspecific in the majority of cases. Only a small proportion of patients have axial inflammation as the major cause of their back complaints with chronic inflammatory back pain (IBP) as the most prominent clinical feature of spondyloarthritis (SpA). The recognition of IBP and patients with axial spondyloarthritis (axSpA) is challenging in primary care, and it is important to further facilitate the early diagnosis of SpA. Proposals for improving the referral of patients with a possible diagnosis of axSpA include clinical parameters, human leukocyte antigen (HLA) B27, and imaging parameters. Imaging is crucial for the visualization, objective validation, and understanding of back pain. Numerous diseases such as degenerative disk disease, degenerative changes in the intervertebral (facet) joints and the associated ligaments, spinal instability, herniation of the intervertebral disk, and spinal stenosis have to be differentiated in interpreting imaging of the spine. The sacroiliac joints and the spine are of major importance for the diagnosis and classification of axSpA. Conventional radiographs and magnetic resonance imaging (MRI) are the most important imaging technologies for visualization of structural changes such as syndesmophytes and axial inflammation such as sacroiliitis and spondylitis. The pathogenesis of axSpA is largely genetically determined. HLA B27 has the strongest contribution to the total genetic burden, but other major contributors such as endoplasmic reticulum aminopeptidase (ERAP)-1 and interleukin (IL)-23R have also been identified.

Emerging drugs for the treatment of axial and peripheral spondyloarthritis

INTRODUCTION

The topic under discussion is of strong relevance to the field of spondyloarthritis (SpA) because, in addition to established biological, there are new promising compounds. The reason for the review is to put all available data together to allow for an overview on recent developments and to especially inform readers about emerging drugs, biologics and small molecules in the field of SpA.

AREAS COVERED

This review on new therapies in axial and peripheral SpA comprising psoriatic arthritis (PsA) shows, that, in addition to the established anti-TNF agents infliximab, etanercept, adalimumab, golimumab, certolizumab and the first biosimilar approved in the EU, there are at least two emerging biologics in the field of SpA: ustekinumab, a compound targeting IL12/IL-23 via the p40 subunit of both cytokines works for psoriasis and PsA and probably also for Crohn's disease, and the anti-IL-17 antibody secukinumab which has also been shown to work in psoriasis, both compounds seem to also work in ankylosing spondylitis. In addition, the potential of two small molecules, apremilast a phoshodiesterase4 inhibitor and tofacitinib, a januskinase inhibitor is discussed.

EXPERT OPINION

Since, in contrast to rheumatoid arthritis, the therapeutic array in SpA is currently limited to TNF-blockers, and since there is still an unmet need because some patients do not respond to anti-TNF therapy at all or they loose response, new agents with a different mechanism of action are eagerly awaited.

Can suppression of inflammation by anti-TNF prevent progression of subclinical atherosclerosis in inflammatory arthritis?

OBJECTIVE

It remains a matter of debate whether TNF-a antagonists have favourable effects on the cardiovascular (CV) system. This systematic review evaluates the effect of TNF-a blockers on the progression of subclinical atherosclerosis and arterial stiffness in patients with inflammatory arthritis.

METHODS

A search of the MEDLINE and Web of Knowledge databases was conducted to identify studies into the effect of TNF-a antagonists on subclinical atherosclerosis and arterial stiffness in patients with RA, AS and PsA. Carotid intimamedia thickness (cIMT) was used to assess subclinical atherosclerosis. Two methods were used to assess arterial stiffness: pulse wave velocity (PWV) and aortic augmentation index (AIx). Twenty-three studies matching the search criteria were included for analysis.

RESULTS

TNF-a blockers probably are effective in preventing (7/13 studies) or even reversing (5/13 studies) the progression of IMT in patients with RA, AS and PsA who are responding to treatment. With regard to arterial stiffness, PWV was either significantly reduced (7/13 studies) or remained unchanged (6/13 studies) following TNF-a antagonist treatment. Nonetheless, most studies in RA (7/10) reported significant improvement of PWV. AIx remained unchanged in 10 of 13 studies.

CONCLUSION

The balance of evidence suggests that TNF-a antagonists may have a beneficial effect on preventing the progression of subclinical atherosclerosis and arterial stiffness. It remains unknown whether this effect is specific to TNF-a antagonists or relates to better control of inflammation irrespective of the disease modification strategy by which this is achieved.