Longitudinal analysis of autoantibody response to topoisomerase I in systemic sclerosis

Abstract

Objective. To examine serial changes in serum anti-topoisomerase I (anti-topo I) antibody levels in patients with systemic sclerosis (SSc), as well as associations with clinical features and the in vivo activation status of circulating topo I-reactive T and B cells. Methods. Serum anti-topo I antibody levels were serially measured at different time points in 28 SSc patients who were positive for anti-topo I antibody at their first visit (range of followup 6-29 years). The patients were subgrouped according to the disappearance (group 1) or persistence (group 2) of anti-topo I antibody. Clinical findings as well as T and B cell responses to topo I were compared between these 2 groups. Results. Serum anti-topo I antibody disappeared during the period of followup in 6 patients (group 1), but persisted in 22 patients (group 2). Loss of anti-topo I antibody occurred within 10 years after the first visit and independently of treatment. Group 1 patients had less extensive skin and lung involvement and better survival rates than did group 2 patients. Complete loss of anti-topo I antibody followed a reduction in isotype expression and epitope reactivities. The kinetics of in vitro T cell proliferation induced by topo I were delayed and circulating topo I-reactive T cells were less frequently detected in group 1 versus group 2 patients, suggesting that the disappearance of anti-topo I anti-body was due to loss of activation of topo I-reactive T cells. In vitro production of anti-topo I antibody in peripheral blood mononuclear cell cultures in response to antigenic stimulation in both group 1 and group 2 patients indicated persistence of anti-topo I antibody-producing "memory" B cells even after the loss of serum anti-topo I antibody. Conclusion. Our results indicate that there is a distinct subset of anti-topo I-positive SSc patients who lose anti-topo I antibody during the disease course and have a favorable outcome. In vivo production of anti-topo I autoantibody may require antigenic stimulation that activates topo I-reactive T and B cells.

Analysis of Soluble and Cell Surface Factors Regulating Anti-DNA Topoisomerase I Autoantibody Production Demonstrates Synergy Between Th1 and Th2 Autoreactive T Cells

“…As shown in Fig. 2, anti-topo I Ab production was also blocked by addition of anti-HLA-DR or anti-CD40L mAb, but not by anti-HLA-DQ mAb, confirming our previous observations regarding the MHC class II restriction of this response using bulk PBMC cultures (13). Similar results were obtained when topo Ispecific T cell clones T2-5, T2-7, and D3-5 were used or when B cells from an another anti-topo I-positive SSc subject T1 were used (data not shown).…”

“…We have detected topo Ispecific T cell proliferative responses in individuals with certain HLA-DR types, including DR15, DR11, and DR7 (12). Furthermore, B cells from anti-topo I-positive SSc subjects did not spontaneously produce anti-topo I Ab in vitro, but did produce this autoantibody in an Ag-dependent manner when cultured with topo I-specific T cells (13).…”

“…Unless indicated otherwise, SD are Ͻ15% of the mean value or Ͻ0.010 (OD 405 ). The presence of anti-topo I Ab in culture supernatants was assessed by immunoprecipitation using 35 S-labeled HeLa cell extracts (13,21). In some samples the specificity of anti-topo I reactivity in the ELISA was confirmed by ELISA inhibition assay, in which topo I and MBP (100 g/ml) were used as competitors (7).…”

“…To identify the cell surface and soluble factors involved in autoantibody production in SSc, we have developed a culture system capable of reconstituting the components necessary for the synthesis of anti-topo I Ab in vitro (13). Using bulk PBMC in this system, we found that the production of anti-topo I Ab is dependent on cognate and HLA-DR-restricted T-B cell interaction.…”

Effector CD8+ T cells in systemic sclerosis patients produce abnormally high levels of interleukin‐13 associated with increased skin fibrosis

“…T cells have been found to be necessary for the production of antitopoisomerase I antibodies in SSc (8). Autoantibodies against a variety of nuclear proteins are a nearly uniform feature of patients with SSc (9).…”