MicroRNAs (miRNAs) are small non-coding RNAs that post-transcriptionally regulate gene expression via inhibiting mRNA translation or degrading mRNA. Since the discovery of miRNAs, dysregulated miRNAs have been identified in human patients with various diseases. Moreover, the role of miRNAs in biological processes, including immune homeostasis and autoimmunity pathogenesis, has been widely investigated. Systemic lupus erythematosus (SLE) is a chronic inflammatory autoimmune disease that causes systemic damage to multiple organs and is characterized by the production of pathogenic autoimmune antibodies. In previous work in my lab, a set of commonly upregulated miRNAs in splenic lymphocytes of three lupus-prone mouse models was identified, including the miR-183-96-182 cluster (miR-183C) and miRNAs located at DLK1-DIO3 region.
The work presented in this dissertation focuses on comparing the dysregulation pattern of miRNAs from different cell sources of lupus-prone mice and investigating the potential role of miR-183C in the pathogenesis of SLE and inflammation. The first goal was to test whether dysregulated miRNAs initially identified in the spleen of MRL/lpr mice, a standard model for SLE, is also reflected in the peripheral blood mononuclear cells (PBMCs) as PBMC is the primary source of lymphocytes in human patients. In MRL/lpr mice, we found that dysregulated miRNAs in PBMCs were overall comparable to those identified in the splenic lymphocytes. Further, comparing dysregulated miRNAs between mice and humans showed a similarity in the dysregulation of miRNAs in PBMCs of murine and human lupus. Among the upregulated miRNAs, the expression of three miRNAs of miR-183C was found to be commonly upregulated. To investigate the role of miR-183C, we developed miR-183C in CD2+ cells of C57BL/6 Faslpr/lpr (miR-183C-/-B6/lpr) mice. In miR-183C-/-B6/lpr mice, we observed a significantly reduced level of anti-dsDNA in the serum and IgG immunocomplex deposition in the kidney. Importantly, in vitro inhibition of miR-183C in activated splenic lymphocytes led to reduced production of the proinflammatory cytokine, IFN, and Foxo1, a transcription factor that is a target of miR-183C miRNAs.
I also tested for miRNA changes in C57BL/6 Faslpr/lpr mice with conditional deletion of Early Growth Response-2 (EGR2) (Egr2-/- B6/lpr), another knockout mouse developed in our laboratory. Egr2 has recently been shown to regulate immunity and autoimmunity and play a role in lupus. An unexpected observation is that Egr2-/-B6/lpr mice had significantly reduced expression of a group of lupus-related miRNAs that are located at the genomic imprinted DLK1-DIO3 locus. Given that the upregulation of DLK1-DIO3 miRNAs in lupus is subjected to DNA methylation regulation and that the epigenetic regulatory role of EGR2 is emerging in recent studies, reduced representative bisulfite sequencing (RRBS) was performed to evaluate the methylation changes induced by Egr2 deletion. Global DNA hypomethylation and methylation changes at specific sites at DLK1-DIO3 region were noticed in CD4+ T cells of Egr2-/-B6/lpr mice.
Overall, our research suggested a therapeutic effect of inhibiting the miR-183C expression on SLE. The interplay between epigenetic factors could help expand the possibility of controlling epigenetic regulators in autoimmune disease treatment. / Doctor of Philosophy / Systemic lupus erythematosus (SLE) is an autoimmune disease that causes damage to multiple organs. Same with other autoimmune diseases, the exacerbated immune reaction to self-antigen and auto-reactive adaptive immune cells were described in SLE. Currently, the treatment of lupus mainly uses immunosuppressive drugs to inhibit the global immune reaction. Thus, the innovative drug is desperately needed for SLE patients. MicroRNAs (miRNAs) are small RNAs that inhibit the expression of genes by binding to mRNAs in a complimentary manner. Since the discovery of the first microRNA, the pivotal role of microRNAs in immunity and autoimmunity was vigorously investigated. Our lab was the first to describe a set of miRNAs that are commonly upregulated in three murine lupus models. Among these miRNAs, miR-183, miR-96, and miR-182 belong to the miR-183-96-182 cluster (miR-183C).
The aim of the study in this dissertation focused on illuminating the dysregulation pattern of miRNAs in different cell sources in the murine lupus model and the role of miR-183C in the pathogenesis of SLE. We found that miRNAs are similarly dysregulated in peripheral blood mononuclear cells and splenic lymphocytes of MRL/lpr mice. Then we conditionally knocked out the miR-183C in B6/lpr mice and investigated the effect of miR-183C loss on the pathogenesis of autoimmunity. Importantly, we found that the deletion of miR-183C led to a reduced production level of autoantibodies and ameliorated the deposition of immune complexes in the kidney. Moreover, the production of proinflammatory cytokines of splenic lymphocytes was regulated by miR-183C as well. Besides miR-183C, I also investigated the effect of early growth response 2 (EGR2), a transcription factor, on the expression of a set of lupus-related miRNAs and the methylation change at the genome location of these miRNAs.
In summary, miR-183C can be a potential therapeutic target for lupus treatment while clinical human studies are needed to better clarify the effectiveness and efficiency.
| Identifer | oai:union.ndltd.org:VTETD/oai:vtechworks.lib.vt.edu:10919/115426 |
| Date | 14 June 2023 |
| Creators | Wang, Zhuang |
| Contributors | Biomedical and Veterinary Sciences, Ahmed, S. A., Dai, Rujuan, Reilly, Christopher Michael, Luo, Xin |
| Publisher | Virginia Tech |
| Source Sets | Virginia Tech Theses and Dissertation |
| Language | English |
| Detected Language | English |
| Type | Dissertation |
| Format | ETD, application/pdf, application/pdf |
| Rights | In Copyright, http://rightsstatements.org/vocab/InC/1.0/ |
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