Egr2 deletion induced phenotypical and functional changes in CD4-CD8- double negative T cells in B6/lpr mice 2589

Abstract Description A key phenomenon in lupus is the expansion of pathogenic CD4-CD8- double negative T (DNT) cells. We recently reported that conditional deleting Egr2, a transcription factor gene, in B6/lpr mice significantly reduced total IgG/IgM and anti-dsDNA autoantibodies, accompanied by a striking reduction of CD3+DNT cells. DNT cells demonstrate phenotypical and functional heterogeneity in different disease settings. Compared to normal B6 mice, autoimmune-prone B6/lpr mice showed a significant expansion of TCRβ+NK1.1- DNT cells, which are usually pathogenic. This led to a dramatic increase in the ratio of TCRβ+DNT to TCRγδ+DNT, as well as the TCRβ+NK1.1- to TCRβ+NK1.1+ DNT cells. Egr2 deletion significantly reduced TCRβ+NK1.1- DNT cells to correct the imbalance of DNT sub-populations in B6/lpr mice. Egr2 deletion increased IFNγ and IL-10 expression in the gated TCRβ+DNT cells of B6/lpr mice. However, there as a very low IL-17 expression in TCRβ+DNT of B6/lpr mice. The IL-17-expressing cells in the gated CD3+DNT were majority TCRγδ+DNT cells. By performing single-cell RNAseq, we identified a total of ten (0-9) cell clusters from the sorted CD3+DNT cells from Egr2-/-B6/lpr and control Egr2fl/fl mice. Strikingly, clusters 0, 1, 3, and 6 were largely absent in the sorted DNT cells from Egr2-/-B6/lpr mice. Our ongoing study will characterize the function of different DNT clusters. Our data shall provide a new insight into the autoimmune regulatory role of EGR2. Funding Sources Supported by VCOM-VMCVM Center for One-health Research Seed grant program and VMCVM Internal Research Competition (IRC) program. Topic Categories Basic Autoimmunity (BA)