Analysis of the Mechanisms of Anti-DNA Antibody Binding to DNA

Loading...
Thumbnail Image

Date

2020-05-08

Journal Title

Journal ISSN

Volume Title

Repository Usage Stats

669
views
443
downloads

Abstract

Antibodies to DNA (anti-DNA) are a canonical marker for systemic lupus erythematosus (SLE), a prototypic autoimmune disease that is most common in young women and has highly variable immunological and clinical manifestations. Anti-DNA antibodies play a key role in the pathogenesis of lupus as they can form pathogenic immune complexes that can ultimately lead to organ damage. Prior studies showed that the antibody’s charge may influence the formation of immune complexes; DNA is negatively charged because of the phosphodiester backbone and anti-DNA antibodies are rich in positively charged amino acids. To elucidate the mechanisms of anti-DNA antibodies, we wanted to further explore how charge affects antibody binding using as a model a monoclonal antibody. In this study, we tested whether the binding properties of Val-1205, an E310 monoclonal antibody (MAb), are mediated by electrostatic interactions, similar to those identified for serum as well as monoclonal anti-DNA antibodies. For this purpose, we took advantage of this monoclonal antibody that has been re-engineered to express more charge and higher binding avidity to determine how charge affects the association and dissociation of ICs. Enzyme-linked immunosorbent assays (ELISAs) were performed under distinct experimental environments to identify possible changes in antigen-antibody (Ag-Ab) interactions. We found that Val-1205 binds well to DNA in ELISAs and that changing buffer composition without altering pH did not significantly change binding activity. In addition, Val-1205 binding was unchanged by the number of times the antibody had been thawed. However, Val-1205’s binding activity was influenced by salt concentration. When compared to antibodies from SLE patient serum, the Val-1205 antibody had comparable dependence on ionic strength. These results are important since they demonstrate the exquisite dependence on the ionic strength of anti-DNA, reflecting the role of electrostatic interactions. Results presented herein provide new understandings of the mechanism of anti-DNA–DNA interaction and indicate that Val-1205 may be especially dependent on charge-charge interaction. These results also provide an important insight that Val-1205, despite its strong binding affinity, may represent anti-DNA antibodies that are primarily dependent on charge. The dependence on ionic interactions in Val-1205 may be utilized as steppingstones to better understand the immunopathogenesis of lupus.

Department

Description

Provenance

Citation

Citation

Garza Reyna, Angel (2020). Analysis of the Mechanisms of Anti-DNA Antibody Binding to DNA. Retrieved from https://hdl.handle.net/10161/20622.

Scholars@Duke

Pisetsky

David Stephen Pisetsky

Professor of Medicine

Studies in my laboratory concern the immunological properties of DNA as related to two main topics: 1) the induction of anti-DNA responses in systemic lupus erythematosus; and 2) the stimulation of innate immunity by bacterial DNA. These topics are closely linked since we have established novel disease models in which lupus-like illness can be induced in normal mice by bacterial DNA under conditions in which mammalian DNA is inactive. This model has been useful in elucidating mechanisms of DNA antigen drive in autoimmunity.

To pursue these studies, our laboratory conducts investigations in the following areas: 1) specificity of anti-DNA for epitopes on mammalian and bacterial DNA; 2) molecular analysis of murine monoclonal anti-DNA antibodies; 3) histopathological analyses of DNA-immunized mice; 4) in vitro analysis of proliferation, antibody production and cytokine expression in human and murine immune cells; and 5) analysis of DNA binding to cell surface molecules on B cells, T cells and macrophages. Results of these studies have allowed identification of at least two structural motifs that are immunoactive. We are also exploring the impact of chemical modifications of the DNA backbone.

In addition to work on the immunology of DNA, I am also involved in clinical trials related to new immunomodulatory agents in the treatment of rheumatoid arthritis as well as serological markers of disease activity.

The areas of research for which I am known nationally are anti-DNA antibodies, systemic lupus erythematosus and immunological properties of DNA. I have written textbook chapters and reviews on all these subjects.


Material is made available in this collection at the direction of authors according to their understanding of their rights in that material. You may download and use these materials in any manner not prohibited by copyright or other applicable law.