LAUSR

We read with interest the recently published paper from Qaiyum et al 1 demonstrating a novel integrin-expressing mature Crohn's disease (CD)8+ T cell population defined as CD49a+CD103+β7+CD29+ cells in the synovial fluids of ankylosing spondylitis (AS) patients. Although the authors did not analyse gut samples from AS patients, they speculate that these cells might be gut-derived cells. Interestingly, as stated by authors, the transcriptional and phenotypic signature of these cells is reminiscent of human tissue-resident memory T cells (TRM). TRM are a subset of cells important as the first line of defence from infection in mucosal tissues, never studied in spondyloarthritis (SpA).2 For clarifying whether these cells could be of intestinal original, we set up additional analyses, wondering if we could see similar results in paired samples of patients with SpA. Paired gut and synovial samples and fluids and peripheral blood samples (PCMCs) were obtained from patients with SpA (HLA-B27 positive; n=6), …