TCR repertoire profiling revealed antigen-driven CD8+ T cell clonal groups shared in synovial fluid of patients with spondyloarthritis.

Spondyloarthritis (SpA) comprises a number of inflammatory rheumatic diseases with overlapping clinical manifestations. Strong association with several HLA-I alleles and T cell infiltration into an inflamed joint suggest involvement of T cells in SpA pathogenesis. In this study, we performed high-throughput T cell repertoire profiling of synovial fluid (SF) and peripheral blood (PB) samples collected from a large cohort of SpA patients. We showed that synovial fluid is enriched with expanded T cell clones that are shared between patients with similar HLA genotypes and persist during recurrent synovitis. Using an algorithm for identification of TCRs involved in immune response we discovered several antigen-driven CD8+ clonal groups associated with risk HLA-B*27 or HLA-B*38 alleles. We further show that these clonal groups were enriched in SF and had higher frequency in PB of SpA patients vs healthy donors, implying their relevance to SpA pathogenesis. Several of the groups were shared among patients with different SpAs that suggests a common immunopathological mechanism of the diseases. In summary, our results provide evidence for the role of specific CD8+ T cell clones in pathogenesis of SpA.

The Phenotype of Axial Spondyloarthritis: Is It Dependent on HLA-B27 Status?

OBJECTIVE: To describe the radiographic phenotype of axial spondyloarthritis (SpA) according to the presence of HLA-B27. METHODS: An international collaboration compared the radiographic phenotype of axial SpA according to HLA-B27 status. Patients with ankylosing spondylitis (AS) and axial psoriatic arthritis (PsA) were collected. Radiographs were read centrally, blinded to clinical details. The symmetry of the sacroiliac joints and lumbar syndesmophytes and the morphology of syndesmophytes (typical marginal versus atypical chunky), together with the modified Stoke Ankylosing Spondylitis Spine Score and the Psoriatic Arthritis Spondylitis Radiographic Index, were recorded. RESULTS: A total of 244 patients with PsA and 198 patients with AS were included. In PsA, 60 patients (25%) were HLA-B27 positive while in AS, 148 patients (75%) were HLA-B27 positive. Patients with HLA-B27 were younger and more often male and had a longer duration of disease. In multivariable logistic regression, HLA-B27 was significantly associated with syndesmophyte symmetry (odds ratio [OR] 3.02 [95% confidence interval (95% CI) 1.38, 6.61]) and marginal syndesmophytes (OR 1.97 [95% CI 1.16, 3.36]) but not with sacroiliac symmetry. Mean radiographic scores were higher for patients with HLA-B27. CONCLUSION: Patients with axial SpA who are positive for HLA-B27 have more severe radiographic damage, more marginal syndesmophytes, and more frequent syndesmophyte symmetry compared to patients who are negative for HLA-B27.

Electron-induced oxygen desorption from the TiO2(011)-2x1 surface leads to self-organized vacancies.

When low-energy electrons strike a titanium dioxide surface, they may cause the desorption of surface oxygen. Oxygen vacancies that result from irradiating a TiO2(011)-2x1 surface with electrons with an energy of 300 electron volts were analyzed by scanning tunneling microscopy. The cross section for desorbing oxygen from the pristine surface was found to be 9 (+/-6) x 10(-17) square centimeters, which means that the initial electronic excitation was converted into atomic motion with a probability near unity. Once an O vacancy had formed, the desorption cross sections for its nearest and next-nearest oxygen neighbors were reduced by factors of 100 and 10, respectively. This site-specific desorption probability resulted in one-dimensional arrays of oxygen vacancies.