Advances in Spondyloarthritis: Glimpse in the Future

Atul A. Deodhar

Disclosures

Curr Opin Rheumatol. 2018;30(4):301-302. 

Research in the field of spondyloarthritis (SpA) races along all fronts – from investigating the complex role of gut microbiome in the pathogenesis, to new modalities of imaging and finding novel therapies. For a busy rheumatologist, it truly is difficult to stay up-to-date, considering the breathtaking speed of new discoveries in SpA. In this issue of the Current Opinion in Rheumatology, the reader will get a good glimpse of where we stand today, and where the field of spondyloarthritis is headed.

In a provocatively titled essay 'Fecal Transplants in Spondyloarthritis and Uveitis: Ready for a Clinical Trial?' James Rosenbaum and colleagues discuss the role of gut microbiome and its interaction with human genome in the pathogenesis of SpA and uveitis.[1] With burgeoning experimental evidence, they argue that SpA is a microbiome-driven disease, and discuss different treatment paradigms targeting the intestinal microbiome in SpA patients. In a somewhat related review article, Deodhar and Danve discuss the scientific basis of 'complementary and alternative medicine' (CAM) including microbiome alteration, in the treatment of axial SpA.[2] They point out that the principles of modern 'mainstream' medicine are based on scientific discovery, and the mainstream medicine does not differentiate between 'old and new,' 'herbal versus chemical,' and so forth. They argue that if the CAM had a solid scientific footing, it would not be called 'alternative,' and would be accepted as 'mainstream.' They present the available literature and the evidence behind the commonly used complementary medical practices in SpA patients.

The HLA-B27 and ankylosing spondylitis association was originally described in 1973, and since then more than 100 genes that confer susceptibility to ankylosing spondylitis have been described. Wordsworth and colleagues discuss the role of genes in the diagnosis of ankylosing spondylitis, as well as determining the outcome of the disease and response to treatment.[3] Their essay also reviews the progress made over the past decade in understanding the genetic contribution to ankylosing spondylitis and how that may be used to inform the development of new treatments.

In this issue of the Current Opinion in Rheumatology, we have included two timely articles on new modalities of imaging in the diagnosis, and assessment of progression of axial SpA (axSpA). The first article by Weber and Kröber covers when and how to use the MRI of the sacroiliac joints and spine in patients with axSpA.[4] The poor agreement between readers of sacroiliac joint X-rays has led to MRI of the sacroiliac joints and spine emerging as a viable modality for diagnosis and for assessing progression of axSpA. However, the low specificity of the current definition of 'positive MRI'– which is predominantly based on bone marrow edema on the fluid-sensitive sequences – for the diagnosis of axSpA is a concern. Weber and Kröber discuss the progress done on improving the specificity by incorporating the structural changes seen on the T1-weighted images in the decision-making process. The second article on imaging by Ward and Tan describes the use of low-dose computerized tomography (CT) scans in the diagnosis and progression of axSpA.[5] Although CT has been known to be a better modality than the MRI for assessing bony changes in the sacroiliac joints, the radiation dose has been the limiting factor in its routine use in clinical practice. Low-dose CT may change this. CT scan studies in axSpA have shown that the thoracic spine is the most commonly involved part of the axial skeleton with syndesmophytes, and that the syndesmophytes have preferred locations around the vertebral rim rather than being randomly distributed. Low-dose CT of the spine is more sensitive than plain radiographs, and hence this modality is likely to play very important role in future longitudinal studies on novel agents investigating structural damage.

Lastly, in a special article, van Vollenhoven and van de Sande compare and contrast the clinical trials in the field of rheumatoid arthritis (RA) versus SpA.[6] They discuss what lessons can be learned from the RA clinical trials – which are probably a decade ahead of the SpA trials whenever one considers the different trials designs used in these two conditions.

We hope this issue of the Current Opinion on 'Spondyloarthritis' gives the readers a sneak peek in this exciting field, and may encourage them to read more.

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