The Role of Hypobromous Acid in Renal Disease

过多地产生活性氧物种(ROS)是导致适应不良的重要原因 肾脏炎症和纤维化。虽然大多数人的注意力都集中在超氧化物上，但氢 过氧化氢(H_2O_2)等ROS，我们最近的工作重点是次溴酸(HOBr)作为一种重要的 罗斯。动物的血红素过氧化物酶利用过氧化氢和溴-作为底物来产生高溴。HOBR，化学上的表亲 漂白剂(HOCl)是一种能够破坏蛋白质、脂质和核酸的强氧化剂，通常 促进组织损伤。 我们最近发现一种细胞外基质(ECM)蛋白，即过氧化物酶(Pxdn)也 生成HOBR。以HOBr为反应中间体，合成了新型磺胺(S=N)交联剂--磺胺-2-甲基-2-苯基-2-苯基-2，5-二甲基苯并二异氰酸酯. IV型胶原是基底膜(BM)的重要组成部分，如肾小球基底膜(GBM)。在……里面 我们发现Pxdn和磺胺交联物的缺失损害了基底膜和 组织完整性导致幼虫致死。然而，Pxdn基因敲除(KO)小鼠是可行的，但证明了 降低磺胺交联度和BM强度。根据这一表型，我们预计单侧输尿管 梗阻(UUO)和肾小管内压力增加将导致更大的肾小管BM拉伸和 机械应力对肾小球肾炎小鼠肾小管细胞的影响因此，Pxdn KO小鼠将表现出增加的 肾脏炎症和纤维化。矛盾的是，PxdNKO小鼠的肾脏炎症和 HOBR介导的氧化损伤减少的纤维化。根据这些数据，我们假设Pxdn 通常使用HOBR来交联IV型胶原并支持组织完整性，但当调节失调时，Pxdn 产生过量的HOBR，导致氧化损伤和组织损伤。 为了验证这一假设，在目标1中，我们将确定PxdN功能丧失是否对肾脏具有保护作用 炎症程度和部位不同的损伤，与肾小球和肾小管间质病变不同。 目标2将研究HOBR如何改变肾细胞行为以促进肾小管间质纤维化和炎症， 包括使用质谱学来鉴定HOBr介导的蛋白质氧化修饰。在《目标3》中， 我们将从机制上解决PxdN如何使用HOBR使IV型胶原蛋白交联，同时避免附带损害 其他生物分子。综上所述，这项提议旨在定义HOBR在肾脏炎症中的新角色 和纤维化症。这些研究希望使针对HOBR治疗慢性肾脏疾病的策略合理化。

The excessive generation of reactive oxygen species (ROS) significantly contributes to maladaptive renal inflammation and fibrosis. While most attention has been directed towards superoxide, hydrogen peroxide (H2O2), and other ROS, our recent work has focused on hypobromous acid (HOBr) as an important ROS. Animal heme peroxidases produce HOBr using H2O2 and Br- as substrates. HOBr, a chemical cousin of bleach (HOCl), is a powerful oxidant capable of damaging proteins, lipids, and nucleic acids and typically promotes tissue injury. We recently discovered that an extracellular matrix (ECM) protein known as peroxidasin (Pxdn) also generates HOBr. Pxdn uses HOBr as an anabolic, reactive intermediate to form novel sulfilimine (S=N) cross- links in collagen IV, a prominent constituent of basement membranes (BM), such as glomerular BM (GBM). In Drosophila, we found that loss of Pxdn and sulfilimine cross-links compromised basement membrane and tissue integrity leading to larval lethality. However, Pxdn knock-out (KO) mice are viable but demonstrate reduced sulfilimine cross-links and BM strength. Based on this phenotype, we expected that unilateral ureteral obstruction (UUO) and increased intratubular pressures would lead to greater tubular BM stretch and mechanical stress on tubular cells in Pxdn KO mice. Consequently, Pxdn KO mice would exhibit increased renal inflammation and fibrosis. Paradoxically, Pxdn KO mice demonstrated less renal inflammation and fibrosis with diminished HOBr mediated oxidative damage. Based on these data, we hypothesize that Pxdn normally uses HOBr to cross-link collagen IV and support tissue integrity, but when dysregulated, Pxdn generates excessive HOBr leading to oxidative damage and tissue injury. To test this hypothesis, in Aim 1, we will determine whether Pxdn loss of function protects against renal injury that varies in extent of inflammation and localization contrasting glomerular and tubulointerstitial disease. Aim 2 will examine how HOBr alters renal cell behavior to promote tubulointerstitial fibrosis and inflammation, including the use of mass spectrometry to identify HOBr mediated oxidative modifications of proteins. In Aim 3, we will mechanistically address how Pxdn uses HOBr to cross-link collagen IV yet avoid collateral damage to other biomolecules. Taken together, this proposal aims to define a novel role for HOBr in renal inflammation and fibrosis. These studies hope to rationalize a strategy to target HOBr to treat chronic kidney disease.