LIPOXYGENASE PRODUCTS IN GLOMERULAR IMMUNE INJURY

在以前的研究中，我们描述了花生四烯酸5-， 15-脂氧合酶（LO）产物（白三烯（LT和脂氧素（LX） 大鼠肾单位。 随后，我们和其他人提供了证据， LT在促进白细胞浸润/活化，蛋白尿， 实验性肾小球系膜增生和功能恶化 大鼠肾小球肾炎。 肾小球中LT和LXx的形成 炎症由中性粒细胞/巨噬细胞内的总合成引起，或 通过白细胞产生的中间体的跨细胞代谢， LTA 4通过内皮细胞和系膜细胞以及浸润的血小板， 产量LT C4、D4、B4和IXA 4。LT生物合成受到严格调控; 主要增加发生在受伤的前48小时，其次是 抑制至损伤前水平，表明内源性 抗炎途径。 我们发现了15-LO 产物LXA 4和15-（S）-羟基二十碳四烯酸[15-（S）-HETE}， 在中性粒细胞和巨噬细胞- 肾小球免疫损伤的介导阶段。 其中包括直接 抑制LT的合成和作用。 值得注意的是， 15-LO产物超出LT拮抗作用，延伸至普遍下调 中性粒细胞趋化性，粘附和激活，以及显着 抑制巨噬细胞活化。 在这里，我们建议审查 生物合成和病理生理调节的潜在机制 这些白细胞活化的内源性途径的意义， 在肾小球炎症期间失活。 具体来说，我们将使用 人血单核细胞（PEM）和系膜细胞（MC）来检验这一假设 从巨噬细胞和淋巴细胞释放的特定细胞因子发挥了 在影响净平衡从赞成到反对的转变中起着至关重要的作用。 随着肾小球炎症进展，炎症脂质介质释放 从急性期到亚急性期。 我们的研究结果表明， 5-LO、15-LO、LTA 4-水解酶和5-LO的mRNA编码水平的变化 脂氧合酶激活蛋白（FLAP），通过白细胞介素1b（IL-1b）、IL-4、IL- 13和g-干扰素，从而提供了一种机制， 调节白细胞中类花生酸的合成，以及通过 跨细胞途径。 我们将这些研究与体内模型相结合， 肾小球肾炎在大鼠和小鼠中的病理生理相关性 这些相互作用进行了测试。 我们将评估肾小球功能， 5-和15-LO基因缺失大鼠肾小球损伤的组织学变化 小鼠和肾小球肾炎大鼠，其中肾类花生酸酶或 通过体内转染来操纵细胞因子基因表达 技术. 对内源性亲核平衡调节的认识 肾小球肾炎期间的炎症影响可能提供 设计干预战略的机会 免疫复合物引发的疾病通过抗- 炎症介质。

In previous studies, we characterized the actions of arachidonate 5-, and 15- lipoxygenase (LO) products {leukotrienes (LTs and lipoxins (LXs)] in the rat nephron. Subsequently, we and others provided evidence supporting a role for LTs in promoting leukocyte infiltration/activation, proteinuria, mesangial proliferation and functional deterioration during experimental glomerulonephritis in the rat. Formation of LTs and LXx in glomerular inflammation arises from total synthesis within neutrophils/macrophages, or through transcellular metabolism of the leukocyte-generated intermediate, LTA4, by endothelial and mesangial cells and infiltrating platelets, to yield LTs C4, D4, B4, and lXA4.LT biosynthesis is regulated tightly; a major increase occuring in the first 48 hrs of injury, followed by suppression to pre-injury levels, suggesting the activation of endogenous counter-inflammatory pathways. We have discovered evidence that the 15-LO products, LXA4 and 15-(S)-hydroxyeicosatetraenoic acid [15-(S)-HETE}, exert potent anti-inflammatory actions during the neutrophil and macrophage- mediated phases of glomerular immune injury. These include direct inhibition of LT synthesis and actions. Significantly, the activities of 15-LO products extend beyond LT antagonism to a generalized down-regulation of neutrophil chemotaxis, adhesion, and activation, as well as marked suppression of macrophage activation. Here, we propose to examine the mechanisms underlying the regulation of biosynthesis and pathophysiologic significance of these endogenous pathways of leukocyte activation and inactivation during glomerular inflammation. Specifically, we will use human blood monocytes (PEM) and mesangial cells (MC) to test the hypothesis that specific cytokines released from macrophages and lymphocytes play a crucial role in effecting the switch in the net balance from pro- to anti- inflammatory lipid mediator release, as glomerular inflammation progress from acute to subacute phases. Our findings demonstrate direct regulation of the levels of mRNA encoding for 5-LO, 15-LO, LTA4-hydrolase and five- lipoxygenase activating protein (FLAP), by interleukin 1b(IL-1b), IL-4, IL- 13, and g-interferon in PBM and MC, thereby providing a mechanism for the regulation of eicosanoid synthesis in leukocytes, as well as via transcellular routes. We will couple these studies with in vivo models of glomerulonephritis in rats and mice in which the pathophysiologic relevance of these interactions is tested. We will assess glomerular functions and histologic changes during glomerular injury in 5- and 15-LO gene-deleted mice, and in glomerulonephritis rats in which renal eicosanoid enzyme or cytokine gene expression are manipulated by in vivo transfection techniques. Insight into the regulation of the endogenous balance of pro- and inflammatory influences during glomerulonephritis may provide an opportunity for the design of interventional strategies aimed at arresting immune complex-initiated diseases through preferential expression of anti- inflammatory mediators.