Recent studies have shown that early growth response 2 (EGR2) is highly induced in activated T cells and regulates T cell functions. In normal C57BL/6 (B6) mice, deletion of EGR2 in lymphocytes results in the development of lupus-like systemic autoimmune disease, which implies indirectly an autoimmune protective role of EGR2. Conversely, increased EGR2 gene expression is suggested to link with high risk of human lupus. In the present studies we sought to clarify the expression and inflammation regulatory role of EGR2 in murine lupus T cells directly. We performed RT-qPCR analysis and found a significant increase of EGR2 mRNA expression in human lupus PBMCs and in CD4+ T cells from three different murine lupus models including MRL-lpr, B6-lpr, and B6.sle123 mice at diseased stage when compared to age-matched control MRL or B6 mice. By performing intracellular flow cytometry analysis, we found that EGR2 protein expression was significantly increased in resting lupus (either MRL-lpr or B6.sle123) CD4+ T cells when compared to CD4+ T cells from their respective non-autoimmune controls. However, there was no difference of EGR2 protein expression in anti-CD3 and anti-CD28 stimulated control and lupus CD4+ T cells since there was a stronger induction of EGR2 in activated control CD4+ T cells. EGR2 expression was significantly increased in MRL-lpr mice at an age when lupus is manifested. To understand further the function of elevated EGR2 in lupus CD4+ T cells, we inhibited EGR2 with a specific siRNA in vitro in splenocytes from MRL-lpr and control MRL mice at 15 weeks-of-age. We found that EGR2 inhibition significantly reduced IFNγ production in PMA and ionomycin activated MRL-lpr lupus CD4+ T cells, but not control MRL CD4+ T cells. We also found that inhibition of EGR2 in vitro suppressed the Th1 differentiation in both MRL and MRL-lpr naïve CD4+ T cells. EGR2 is highly upregulated in human and murine lupus cells. Our in vitro data suggest a positive role of EGR2 in the regulation of Th1 differentiation and IFNγ production in lupus effector CD4+ T cells.

中文翻译：

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EGR2 升高并正调节狼疮 CD4+ T 细胞中炎性 IFNγ 的产生。

最近的研究表明，早期生长反应 2 (EGR2) 在活化的 T 细胞中被高度诱导并调节 T 细胞功能。在正常 C57BL/6 (B6) 小鼠中，淋巴细胞中 EGR2 的缺失导致狼疮样全身性自身免疫病的发展，这间接暗示了 EGR2 的自身免疫保护作用。相反，EGR2 基因表达增加被认为与人类狼疮的高风险有关。在目前的研究中，我们试图直接阐明 EGR2 在鼠狼疮 T 细胞中的表达和炎症调节作用。我们进行了 RT-qPCR 分析，发现与 MRL-lpr、B6-lpr 和 B6.sle123 小鼠在患病阶段相比，人类狼疮 PBMC 和 CD4+T 细胞中 EGR2 mRNA 的表达显着增加。年龄匹配的对照 MRL 或 B6 小鼠。通过进行细胞内流式细胞术分析，我们发现与来自各自非自身免疫对照的 CD4+ T 细胞相比，静息狼疮（MRL-lpr 或 B6.sle123）CD4+ T 细胞中的 EGR2 蛋白表达显着增加。然而，在抗 CD3 和抗 CD28 刺激的对照和狼疮 CD4+ T 细胞中 EGR2 蛋白表达没有差异，因为在激活的对照 CD4+ T 细胞中 EGR2 的诱导更强。EGR2 表达在 MRL-lpr 小鼠中在狼疮出现的年龄显着增加。为了进一步了解升高的 EGR2 在狼疮 CD4+ T 细胞中的功能，我们在来自 15 周龄的 MRL-lpr 和对照 MRL 小鼠的脾细胞中用特定的 siRNA 在体外抑制了 EGR2。我们发现 EGR2 抑制显着降低了 PMA 和离子霉素激活的 MRL-lpr 狼疮 CD4+ T 细胞中 IFNγ 的产生，但不影响对照 MRL CD4+ T 细胞。我们还发现体外抑制 EGR2 抑制了 MRL 和 MRL-lpr 幼稚 CD4+ T 细胞中的 Th1 分化。EGR2 在人和鼠狼疮细胞中高度上调。我们的体外数据表明 EGR2 在调节狼疮效应 CD4+ T 细胞中 Th1 分化和 IFNγ 产生中发挥积极作用。