The role of lysyl oxidase like-2 in chronic kidney disease

慢性肾脏病（CKD）是一个世界性的问题，其原因是肾脏结构的损害 进展至肾功能完全丧失，也称为终末期肾病（ESRD）。 据估计，美国超过15%的成年人患有CKD。ESRD无法治愈， 目前的治疗包括血液透析和肾移植，它们昂贵， 生活质量的负担。纤维化是与进展相关的病理表现的中心 从CKD到ESRD由于不溶性胶原蛋白的积累，肾功能逐渐下降 以及肾实质中的其他ECM蛋白。肾素-血管紧张素系统的药理学阻断 减缓肾功能下降，但不一定能阻止纤维化进展， 需要新的抗纤维化疗法。赖氨酰氧化酶样-2（LOXL 2）已成为一种有吸引力的药物 靶向肾纤维化，因为它是一种ECM重塑酶， 沉积和降解。然而，L0 XL 2促进L0 XL 2的细胞和分子机制是不确定的。 肾纤维化和CKD进展还不是很清楚。 在这个建议中，我们表明LOXL 2在人肾活检和实验小鼠中上调， 肾脏疾病的模型。我们的初步研究表明，抑制LOXL 2显著改善肾脏 糖尿病小鼠肾功能下降和肾纤维化。探索LOXL 2分子机制的体外研究 表达提示促纤维化转化生长因子β（TGF-β）和缺氧是肝纤维化的关键调节因子。 肾小球和肾小管。此外，我们表明细胞外LOXL 2直接 激活肾皮质成纤维细胞，表明LOXL 2的一种新的致病功能， 肾纤维化基于这些发现，我们推测LOXL 2参与了CKD的发病机制 通过促进胶原交联和激活肾成纤维细胞。我们将通过以下方式来检验这一假设：1） 使用遗传学和药理学方法结合CKD的损伤小鼠模型，2）探索 体外系统中的细胞和分子机制，以及3）使用最新技术水平的质谱法 技术来阐明肾纤维化中胶原的生化变化。因此，在本项目中，我们建议3 具体目的：确定LOXL 2催化的胶原交联的生化机制（目的1）; 确定LOXL 2在肾小球硬化（Aim 2）和肾小管间质纤维化（Aim 3）中的致病作用。 从这些研究中获得的知识不仅将作为更好地理解 LOXL 2在肾纤维化中的作用，也有助于开发新的、有效的治疗方法， CKD的进展。

Chronic kidney disease (CKD) is a world-wide problem that results from the damage of renal structures progressing to the complete loss of kidney function also known as end-stage renal disease (ESRD). Estimations indicate that more than 15% of adults in United States have CKD. There is no cure for ESRD and current therapies include hemodialysis and kidney transplant which are expensive and place a significant burden on the quality of life. Fibrosis is central to the pathologic manifestations associated with the progression of CKD to ESRD. Kidney function declines progressively as results from the accumulation of insoluble collagen and other ECM proteins in the renal parenchyma. Pharmacological blockade of the renin-angiotensin system slows down renal function decline, but it does not necessarily stop fibrosis progression, manifesting the urgent need for new antifibrotic therapies. Lysyl oxidase like-2 (LOXL2) has emerged as an attractive pharmaceutical target in renal fibrosis because it is an ECM-remodeling enzyme that crosslinks collagen regulating its deposition and degradation. However, the cellular and molecular mechanism by which LOXL2 contributes to kidney fibrosis and CKD progression are not well understood. In this proposal, we show that LOXL2 is upregulated in human kidney biopsies and experimental mouse models of kidney disease. Our pilot studies showed that inhibition of LOXL2 significantly ameliorated kidney function decline and renal fibrosis in diabetic mice. In vitro studies exploring molecular mechanism of LOXL2 expression suggest that profibrotic transforming growth factor beta (TGF-) and hypoxia are key regulators in the glomerulus and tubulointerstitium, respectively. Moreover, we show that extracellular LOXL2 directly activates renal cortical fibroblasts, suggesting a novel pathogenic function of LOXL2 that may further contribute to renal fibrosis. Based on these findings, we hypothesize that LOXL2 contributes to the pathogenesis of CKD both by promoting collagen crosslinking and by activating renal fibroblasts. We will test this hypothesis by 1) using genetic and pharmacological approaches combined with injury mouse models of CKD, 2) exploring cellular and molecular mechanism in in vitro systems, and 3) using state of the art mass spectrometry technologies to elucidate biochemical changes of collagen in renal fibrosis. Thus, in this project we propose 3 specific aims: to determine the biochemical mechanism of LOXL2-catalyzed collagen crosslinking (Aim 1); to determine the pathogenic role of LOXL2 in glomerulosclerosis (Aim 2) and tubulointerstitial fibrosis (Aim 3). The knowledge gained from these studies will not only serve as a foundation to better understand the role of LOXL2 in renal fibrosis, but also contribute to the development of novel, effective therapies to stop the progression of CKD.