Session Title: Systemic Lupus Erythematosus - Animal Models
Session Type: Abstract Submissions (ACR)
Background/Purpose: Immune dysregulation underlies the complex pathogenesis of SLE. Infection with Epstein Barr Virus (EBV) and expression of latent protein Epstein Barr Virus Nuclear Antigen-1 (EBNA-1, a humoral molecular mimic with SLE associated autoantigens) has been linked with SLE. Acting in an enhanced and sustained manner, the Latent Membrane Protein-1 (LMP1, another major EBV latent protein) cytoplasmic tail is necessary and sufficient as a functional mimic of the TNF Receptor, B cell stimulatory molecule CD40. Mice were created expressing a transgene (Tg) for the chimeric molecule mCD40-LMP1 (containing the cytoplasmic tail of LMP1) and bred onto a CD40-/- background to remove endogenous CD40. The mCD40-LMP1 Tg mice have normal T-dependent antibody responses, spontaneous germinal center formation, and autoantibodies by 2-3 months of age. However, no overt autoimmune disease or early death develops in this model. This study evaluates the nature of the immune response to EBNA-1 in mCD40-LMP1 Tg mice and whether the addition of a molecular mimic in this model could accelerate lupus pathogenesis.
Methods: mCD40-LMP1 Tg, full length mCD40 Tg (Tg strain control), and congenic C57Bl/6 (B6) mice (8-12 weeks of age) were immunized (in CFA) and boosted (in IFA) with EBNA-1 over an 8-week course. Saline/adjuvant and naïve control mice were also employed. Draining lymph node cells were cultured in antigen-recall assays stimulated with EBNA-1, the EBNA-1 antigenic epitope PPPGRRP (GRR), the cross-reactive autoantigen Sm, or the Sm antigenic epitope PPPGMRPP (GMR). Proliferation was measured by 3H-Thymidine incorporation and culture supernatant cytokines by xMAP multiplex assay. Serum antibodies to EBNA-1, autoantibodies, and BUN and creatinine levels were also assessed.
Results: Anti-EBNA-1 antibody levels are comparable in mCD40-LMP1 Tg, mCD40 Tg and B6 congenic mice. EBNA-1 specific proliferative and inflammatory cytokine responses, including IL-6, IL-17, IFN-γ, and TNF-α, are significantly enhanced (p < 0.0001) in mCD40-LMP1 Tg compared to mCD40 Tg, B6 mice, and adjuvant and naïve control mice. In addition, mCD40-LMP1 Tg mice immunized with EBNA-1 exhibit significantly enhanced cellular responses (p < 0.0001) to the EBNA-1 antigenic epitope GRR and cross-react to the autoantigen Sm, as well as its antigenic epitope GMR. The cross-reactive cellular response to GRR and Sm starts within 10 days post-immunization with EBNA-1 in mCD40-LMP1 Tg mice. Cross-reactivity to the Sm epitope GMR occurs within 4 weeks after initial immunization. Enhanced cellular immune dysregulation with EBNA-1 immunization in mCD40-LMP1 mice is accompanied by enhanced splenomegaly, increased serum BUN and creatinine levels, and elevated anti-dsDNA and ANA autoantibody levels (p <0.0001 compared to mCD40 Tg and B6 mice, p < 0.01 compared to adjuvant and naïve mCD40-LMP1 mice).
Conclusion: Mice Tg for mCD40-LMP1 exhibit enhanced cellular responses to EBNA-1. In the presence of LMP1, EBNA-1 induces cellular molecular mimicry to the SLE associated autoantigen Sm. These data suggest that expression of EBV latent proteins EBNA-1 and LMP1 may contribute to immune dysregulation that leads to pathogenic autoantigen-specific inflammation in lupus.
M. E. Munroe,
J. R. Anderson,
T. F. Gross,
L. L. Stunz,
G. A. Bishop,
J. A. James,
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ACR Meeting Abstracts - https://acrabstracts.org/abstract/epstein-barr-virus-cd40-functional-mimic-latent-membrane-protein-1-drives-cellular-molecular-mimicry-in-the-presence-of-epstein-barr-virus-nuclear-antigen-1-in-a-novel-murine-model-of-lupus-like-disea/