Mutation of RPA2 May Be Connected to Systemic Lupus Erythematosus

Abstract

Systemic Lupus Erythematosus (SLE) is an autoimmune disease that affects multiple organ systems and is characterized by the production of autoantibodies (Kumar, Abbas et al. 2023). Disease injury is caused by antigen-antibody complex deposition and antibodies binding to various tissues. SLE is quite common with 20 to 150 cases per 100,000 in the united states; it primarily affects women with a ratio of 9:1 females to males (Kumar, Abbas et al. 2023, Schur and Hahn 2023). Many genetic associations have been made to SLE such as mutatedRPA2 which is single nucleotide polymorphisms that is enriched in SLE patients. Replication protein A (RPA) is a heterotrimer that binds ssDNA. RPA is involved with multiple pathways in the cell such as DNA repair and DNA replication (Byrne and Oakley 2019). The aim of this thesis was the characterization of the RPA genetic variant with the goal of determining if it was sufficient to induce a for SLE phenotype. The hypothesis of this project: the RPA2 (RPA32) genetic variant plays a functional role in the etiology of SLE. RPA2 genetic variant was created using CRISPR. The characterization of RPA was done through a series of experiment: anti-nuclear antibody staining, cytokine profiling, kidney histology, glomerular deposition, ELISA for total IgG and IgM, ELISA for ssDNA and dsDNA, and germinal centers in a mouse model. There was a significant difference found in the anti-nuclear antibody staining and the cytokine profiling comparing mice with wild type RPA2 versus a mutant allele. The anti-nuclear antibody staining showed significantly higher levels in the 6-month group of RPA2 mutant mice compared to wild type mice. In addition, significantly higher levels of ANA were observed in the RPA2 G15R/ R homozygous versus wild-type mice at 12-months of age. IL-6, IL-10, and IL-15 had the most change in cytokine levels between wild type and mutant mice. Data suggest there could be an association between RPA2 and the development of SLE. However further studies are warranted. In the future it will be important to look at other phenotypes related to SLE, such as in the skin and GI tract. It would also be good to try stressing the mice with different stressors such as UV light and viruses to see if that would give a stronger immunological response consistent with SLE.