Autoimmunity to DNA and Nucleosomes in Binary Tetracycline-Regulated Polyomavirus T-Ag Transgenic Mice

Abstract

The mechanism(s) responsible for autoimmunity to DNA and nucleosomes in SLE is largely unknown. We have demonstrated that nucleosome-polyomavirus T-Ag complexes, formed in context of productive polyomavirus infection, activate dsDNA-specific B cells and nucleosome-specific CD4+ T cells. To investigate whether de novo expressed T-Ag is able to terminate nucleosome-specific T cell tolerance and to maintain anti-dsDNA Ab production in nonautoimmune mice, we developed two binary transgenic mouse variants in which expression of SV40 large T-Ag is controlled by tetracycline, MUP tTA/T-Ag (tet-off), and CMV rtTA/T-Ag (tet-on) mice. Data demonstrate that MUP tTA/T-Ag mice, but not CMV rtTA/T-Ag mice, are tightly controlling T-Ag expression. In MUP tTA/T-Ag transgenic mice, postnatal T-Ag expression activated CD8+ T cells but not DNA-specific B cells, while immunization with T-Ag and nucleosome-T-Ag-complexes before T-Ag expression resulted in elevated and remarkably stable titers of anti-T-Ag and anti-dsDNA Abs and activation of T-Ag-specific CD4+ T cells. Immunization of nonexpressing MUP tTA/T-Ag mice resulted in transient anti-T-Ag and anti-dsDNA Abs. This system reveals that a de novo expressed DNA-binding quasi-autoantigen maintain anti-dsDNA Abs and CD4+ T cell activation once initiated by immunization, demonstrating direct impact of a single in vivo expressed molecule on sustained autoimmunity to DNA and nucleosomes.

Nucleosomes possess a high affinity for glomerular laminin and collagen IV and bind nephritogenic antibodies in murine lupus-like nephritis

“…Kidneys from BALB/c and B/W mice (Harlan, Bicester, UK) were fixed in 8% depolymerised paraformaldehyde and epoxy-embedded (for TEM), or frozen in nitrogen (for IEM and TUNEL-IEM) as described previously 14 19. Sera were stored at −20°C until use.…”

Critical comparative analyses of anti–α‐actinin and glomerulus‐bound antibodies in human and murine lupus nephritis

“…For IEM, ultrathin cryosections of kidneys from BALB/c or nephritic B/W mice or murine skeletal muscle were prepared as previously described (34). In vivo-bound glomerular autoantibodies were detected by incubating the sections with rabbit anti-mouse IgG antibodies (ICN/Chappel, Aurora, OH) followed by protein A-5-nm gold (University of Utrecht, The Netherlands).…”

Increased prevalence of polyomavirus BK viruria that correlates with thrombocytopenia in patients with systemic lupus erythematosus on intensive immunosuppressive therapy

“…After inoculation with BKV, autoantibodies against DNA and histones were detected in the rabbit's sera [12,13]. It is believed that the human polyomavirus large T antigen may render DNA immunogenic upon binding to nucleosomes [8,14,15].…”