Dysregulated T cells are a major contributor to SLE pathogenesis, and their targeting is an important focus for therapeutic intervention. In the NZM2410 mouse model of lupus, we have determined that the Sle1 locus drives the production of anti-nuclear autoantibodies (ANA). Within Sle1, we have identified two loci, Sle1a1 and Sle1c2, which independently induce the production of activated chromatin-specific CD4+ T cells that provide help to ANA secreting B cells. Importantly, we have demonstrated that Sle1a1 and Sle1c2 each significantly enhance ANA production and immune activation either in in vivo models of lupus pathogenesis. During the last cycle of funding, we have functionally characterized these two loci and we have identified by genetic mapping and candidate gene analysis Pbx1 and Esrrg as the respective genes responsible for Sle1a1 and Sle1c2 phenotypes. The NZM2410 allele of Pbx1 is a novel splice isoform, Pbx1-d, which is expressed at a higher frequency in the CD4+ T cells from SLE patients than healthy controls (HC). Pbx1-d functions as a dominant negative and impairs CD4+ T cell responses to TGF? and all-trans retinoic acid (ATRA), processes recently recognized to play a pivotal role in T cell effector functions. Esrrg regulates oxidative metabolism and its expression is significantly reduced in NZM2410 CD4+ T cells. Metabolic substrate utilization has been identified very recently as another defining mechanism of T cell functions. We hypothesize that Pbx1 and Esrrg contributes to lupus by each regulating CD4+ T cell effector functions through novel mechanisms. The goal of this proposal is to test this hypothesis in the mouse and assess our findings in lupus patients. To achieve this goal, we propose three specific aims, the first two in the mouse, and the third with lupus patients.
Aim 1. To determine the mechanisms by Pbx1-d induce autoreactive CD4+ T cells. We will A) identify the genes differentially targeted by Pbx1 and Pbx1-d by ChIP-Seq analysis in Jurkat T cells with ChIP-PCR validation in primary CD4+ T cells;B) determine how Pbx1-d affects chromatin structure, TGF? and ATRA responses in vitro;and C) validate that Pbx1-d affects CD4 T cell effector function in vivo.
Aim 2. To determine the mechanisms by which Esrrg regulates CD4+ T cells and contributes to lupus. We will A) assess the effect of Esrrg deficiency on T cell functions and lupus;B) characterize the mechanisms by which Esrrg regulates T cell metabolism by combining techniques to analyze metabolism parameters, mitochondrial function, and gene expression;and C) test the hypothesis that Esrrg regulates T cell functions through metabolism. .
Aim 3. To determine how PBX1-d or ESRRG expression affect CD4+ T cell functions in SLE patients. A) We will determine the mechanisms by which PBX1-d expression affect CD4+ T cells by comparing immune gene expression in sorted na?ve, memory, CD25+ Tregs and CD25- Tregs obtained from SLE patients and healthy controls (HC) partitioned on Pbx1-d expression. Functional validation will be conducted T cells in basal conditions as well as after activation or polarization with TGF? and ATRA;B). We will compare metabolic substrate utilization between SLE and HCs CD4+ T cells and determine whether it correlate with Esrrg expression level, effector functions and gene expression. We expect these results to delineate two novel regulatory pathways of T cell effector functions, to provide novel biomarkers for autoreactive T cells as well as identify lupus therapeutic targets.
Systemic lupus erythematosus is an autoimmune disease with no known cure and in need of better treatments to curb morbidity. Murine models of lupus are crucial to understand the pathophysiology of this complex disease based on genetic susceptibility. This project proposes to characterize the mechanisms by which two murine genes, Pbx1 and Esrrg, that we have identified during the previous cycle of funding contribute to lupus pathogenesis and to assess the results we have obtained in the mouse in lupus patients. Each of these genes regulates the function of T cells, which represent key players in the disease process, through novel mechanisms that have been recently identified in these immune cells, but not in lupus.
|Dozmorov, Igor M; Jarvis, James; Saban, Ricardo et al. (2011) Internal standard-based analysis of microarray data2--analysis of functional associations between HVE-genes. Nucleic Acids Res 39:7881-99|
|Sobel, Eric S; Brusko, Todd M; Butfiloski, Ed J et al. (2011) Defective response of CD4(+) T cells to retinoic acid and TGF? in systemic lupus erythematosus. Arthritis Res Ther 13:R106|
|Stohl, William; Jacob, Noam; Guo, Shunhua et al. (2010) Constitutive overexpression of BAFF in autoimmune-resistant mice drives only some aspects of systemic lupus erythematosus-like autoimmunity. Arthritis Rheum 62:2432-42|
|Tchepeleva, Svetlana N; Thurman, Joshua M; Ruff, Katherine et al. (2010) An allelic variant of Crry in the murine Sle1c lupus susceptibility interval is not impaired in its ability to regulate complement activation. J Immunol 185:2331-9|
|Dozmorov, Mikhail G; Guthridge, Joel M; Hurst, Robert E et al. (2010) A comprehensive and universal method for assessing the performance of differential gene expression analyses. PLoS One 5:|
|Cuda, C M; Zeumer, L; Sobel, E S et al. (2010) Murine lupus susceptibility locus Sle1a requires the expression of two sub-loci to induce inflammatory T cells. Genes Immun 11:542-53|
|Te, Jeannie L; Dozmorov, Igor M; Guthridge, Joel M et al. (2010) Identification of unique microRNA signature associated with lupus nephritis. PLoS One 5:e10344|
|Dozmorov, Igor; Lefkovits, Ivan (2009) Internal standard-based analysis of microarray data. Part 1: analysis of differential gene expressions. Nucleic Acids Res 37:6323-39|
|Wan, Suigui; Zhou, Zhenhai; Duan, Biyan et al. (2008) Direct B cell stimulation by dendritic cells in a mouse model of lupus. Arthritis Rheum 58:1741-50|
|Cuda, Carla M; Wan, Suigui; Sobel, Eric S et al. (2007) Murine lupus susceptibility locus Sle1a controls regulatory T cell number and function through multiple mechanisms. J Immunol 179:7439-47|
Showing the most recent 10 out of 14 publications