Endothelia mechanisms of leukocyte accumulation in glomerulonephritis

描述（由申请人提供）：白细胞积聚是炎症性肾脏疾病的标志。TNF是一种调节白细胞运输的有效细胞因子，在动物模型中对肾小球肾炎（GN）的发展至关重要。TNF的生物活性由两种功能不同的TNFR1和TNFR2介导。我们已经证明TNFR2对GN至关重要。TNFR2缺陷小鼠完全免受抗体介导的肾毒性肾炎的影响，肾毒性肾炎与肾白细胞积聚和肾小球补体沉积减少有关。此外，内在实质细胞上的TNFR2对GN是必需的，而不是循环白细胞。值得注意的是，TNFR2在肾病肾的肾小球内皮被诱导。相反，TNFR1的缺乏导致免疫反应增强和肾T细胞积聚导致GN。因此，tnfr在GN中起着不同的作用。本研究的主要目的是确定TNFR2依赖性白细胞积累和肾小球损伤的内在细胞类型和机制。目的1将阐述内皮细胞上的TNFR2参与诱导白细胞募集和随后的肾小球损伤所需的转录程序的假设。白细胞迁移所需的内皮粘附受体依赖的信号机制仍然是谜。我们的初步数据表明，tnf诱导的白细胞转运依赖于DOCK4， DOCK4是最近发现的COM家族的一员，是小gtpase的鸟嘌呤交换因子，我们发现它在培养的内皮细胞和肾小球内皮上高度表达。Aim II将验证内皮粘附受体向DOCK4信号传导调节白细胞迁移和肾小球损伤的假设。这些目标将利用a)建立抗体诱导GN的小鼠模型，以及抗体和tnf诱导的白细胞募集，这些模型适用于活体显微镜；b)肾脏的转录谱分析和生理流动条件下的体外白细胞迁移试验；c)仅在内皮中诱导表达TNFR2的转基因小鼠，以及内皮系中特异性缺乏DOCK4的小鼠。这些目标的完成将增加我们对炎症介导的肾小球损伤的内皮依赖机制的理解，这可能有助于开发治疗GN的新治疗策略。

DESCRIPTION (provided by applicant): Leukocyte accumulation is the hallmark of inflammatory renal diseases. TNF, a potent cytokine that regulates leukocyte trafficking, is essential for the development of glomerulonephritis (GN) in animal models. The biological activities of TNF are mediated by two functionally distinct TNFRs, TNFR1 and TNFR2. We have shown that TNFR2 is critical for GN. TNFR2 deficient mice were completely protected from antibody- mediated nephrotoxic nephritis that was associated with decreased renal leukocyte accumulation and glomerular complement deposition. Furthermore, TNFR2 on intrinsic parenchymal cells but not circulating leukocytes was essential for GN. Notably, TNFR2 was induced on glomerular endothelium of nephritic kidneys. In contrast, a deficiency in TNFR1 resulted in an enhanced immune response and renal T cell accumulation resulting in GN. Thus TNFRs play differential roles in GN. The major objective of this proposal is to identify the intrinsic cell type and mechanisms responsible for TNFR2 dependent leukocyte accumulation and glomerular damage. Aim I will address the hypothesis that TNFR2 engagement on endothelial cells induces a transcriptional program required for leukocyte recruitment and subsequent glomerular injury. The endothelial adhesion receptor dependent signaling mechanisms required for leukocyte transmigration remain enigmatic. Our preliminary data demonstrates that TNF-induced leukocyte transmigration is dependent on DOCK4, a recently identified member of the COM family of guanine exchange factors for small GTPases that we show is highly expressed on cultured endothelial cells and glomerular endothelium. Aim II will test the hypothesis that endothelial adhesion receptor signaling to DOCK4 modulates leukocyte transmigration and glomerular damage. These aims will exploit a) established mouse models of antibody induced GN, and antibody and TNF-induced leukocyte recruitment that are amenable to intravital microscopy, b) transcriptional profiling of nephritic kidneys and in vitro leukocyte transmigration assays under physiological flow conditions, c) transgenic mice with inducible expression of TNFR2 only in the endothelium, and mice lacking DOCK4 specifically in the endothelial lineage. Completion of the aims will increase our understanding of endothelial dependent mechanisms of inflammation mediated glomerular injury that could aid in the development of new therapeutic strategies for the treatment of GN.