This study evaluates the intestinal microbiome and disease activity in patients with spondyloarthropathies receiving immunosuppressive therapy.

Patients will be analysed at two time points in reference to two predefined primary endpoints:

• Changes in intestinal microbiome
• Response to therapy

The investigators want to evaluate if successful treatment of spondylarthropathy coincide with specific changes in the gut flora.

Tumor necrosis factor (TNF)-inhibition is an efficient medication for the treatment of spondyloarthropathy. In a substantial number of cases however, these medications remain ineffective. At present, the scientific community has limited understanding of why some patients are resistant to this medication. The purpose of this study is to understand if the gut flora may associate with treatment response.

Spondyloarthropathies are associated with inflammatory bowel diseases in terms of epidemiology and molecular pathogenesis. Recent studies have also associated spondyloarthropathies with intestinal dysbiosis.

This study is of observational character and integrated in the routine clinical care of patients with spondyloarthropathies at the Rheumatology Clinic, Skane University Hospital, Lund, Sweden. Study participants are asked to deliver blood and fecal sampling at two time-points together with clinical evaluation of disease activity. With an estimated inclusion of 50 patients, at least 20 responders and 20 non-responders are expected to be included and to be compared to each other.

Our primary goal is to investigate the association between change in intestinal microbiome and clinical response to therapy.

In our secondary analyses we will investigate if intestinal microbiome and intestinal inflammation at baseline may predict response to, and adherence to, therapy in these patients.

If successful treatment response of spondyloarthropathy is associated with specific alterations of the gut flora, these results may guide future studies on the impact of dysbiosis and probiotics on this disease.

Inclusion Criteria:

• Fulfilling the Assessment of SpondyloArthritis International Society classification criteria for spondyloarthropathy.
• About to commence treatment with TNF-inhibition

Exclusion Criteria:

• Failure to understand protocol
• A history of alcohol abuse
• Any history of diverticulitis
• A history of failure to comply with prescribed medication
• Ongoing biological therapy

This study encompasses consecutive patients with spondyloarthropathy who by their physician at the Rheumatology Clinic, Skåne University Hospital, have been prescribed a TNF-inhibitor.

Patients who are willing to comply with the study protocoll are included. The study population is consequently not a sample, but encompasses a majority of spondyloarthropathy patients being prescribed this medication at our University clinic.