title: Accumulation of self-reactive naïve and memory B cell reveals sequential defects in B cell tolerance checkpoints in Sjögren's syndrome.
abstract: Sjögren's syndrome (SS) is an autoimmune disease characterised by breach of self-tolerance towards nuclear antigens resulting in high affinity circulating autoantibodies. Although peripheral B cell disturbances have been described in SS, with predominance of naïve and reduction of memory B cells, the stage at which errors in B cell tolerance checkpoints accumulate in SS is unknown. Here we determined the frequency of self- and poly-reactive B cells in the circulating naïve and memory compartment of SS patients. Single CD27-IgD+ naïve, CD27+IgD+ memory unswitched and CD27+IgD- memory switched B cells were sorted by FACS from the peripheral blood of 7 SS patients. To detect the frequency of polyreactive and autoreactive clones, paired Ig VH and VL genes were amplified, cloned and expressed as recombinant monoclonal antibodies (rmAbs) displaying identical specificity of the original B cells. IgVH and VL gene usage and immunoreactivity of SS rmAbs were compared with those obtained from healthy donors (HD). From a total of 353 VH and 293 VL individual sequences, we obtained 114 rmAbs from circulating naïve (n = 66) and memory (n = 48) B cells of SS patients. Analysis of the Ig V gene repertoire did not show significant differences in SS vs. HD B cells. In SS patients, circulating naïve B cells (with germline VH and VL genes) displayed a significant accumulation of clones autoreactive against Hep-2 cells compared to HD (43.1% vs. 25%). Moreover, we demonstrated a progressive increase in the frequency of circulating anti-nuclear naïve (9.3%), memory unswitched (22.2%) and memory switched (27.3%) B cells in SS patients. Overall, these data provide novel evidence supporting the existence of both early and late defects in B cell tolerance checkpoints in patients with SS resulting in the accumulation of autoreactive naïve and memory B cells.
authors.affiliation: Centre for Experimental Medicine & Rheumatology, William Harvey Research Institute, Barts and The London School of Medicine & Dentistry, Queen Mary University of London, John Vane Science Centre, Charterhouse Square, London EC1M 6BQ, United Kingdom.
authors.forename: Elisa
authors.initials: E
authors.lastname: Corsiero
authors.affiliation: Centre for Experimental Medicine & Rheumatology, William Harvey Research Institute, Barts and The London School of Medicine & Dentistry, Queen Mary University of London, John Vane Science Centre, Charterhouse Square, London EC1M 6BQ, United Kingdom.
authors.forename: Nurhan
authors.initials: N
authors.lastname: Sutcliffe
authors.affiliation: Centre for Experimental Medicine & Rheumatology, William Harvey Research Institute, Barts and The London School of Medicine & Dentistry, Queen Mary University of London, John Vane Science Centre, Charterhouse Square, London EC1M 6BQ, United Kingdom.
authors.forename: Costantino
authors.initials: C
authors.lastname: Pitzalis
authors.affiliation: Centre for Experimental Medicine & Rheumatology, William Harvey Research Institute, Barts and The London School of Medicine & Dentistry, Queen Mary University of London, John Vane Science Centre, Charterhouse Square, London EC1M 6BQ, United Kingdom.
authors.forename: Michele
authors.initials: M
authors.lastname: Bombardieri
mesh_terms: D000328:Adult; D000368:Aged; D000974:Antibodies, Antinuclear / Q000276:immunology; D001402:B-Lymphocytes / Q000276:immunology*; D002460:Cell Line; D002469:Cell Separation; D004252:DNA Mutational Analysis; D005260:Female; D006801:Humans; D007108:Immune Tolerance; D007143:Immunoglobulin Heavy Chains / Q000235:genetics; D007147:Immunoglobulin Light Chains / Q000235:genetics; D007135:Immunoglobulin Variable Region / Q000235:genetics; D007156:Immunologic Memory; D008297:Male; D008875:Middle Aged; D012859:Sjogren's Syndrome / Q000235:genetics / Q000276:immunology*; D014019:Tissue Donors
chemical_list: D000974:Antibodies, Antinuclear; D007143:Immunoglobulin Heavy Chains; D007147:Immunoglobulin Light Chains; D007135:Immunoglobulin Variable Region