The Role of Hypobromous Acid in Renal Disease

活性氧（ROS）的过度产生显着有助于适应不良 肾脏炎症和纤维化。虽然大多数注意力都集中在超氧化物上， 过氧化氢（H2 O2）和其他活性氧，我们最近的工作集中在次溴酸（HOBr）作为重要的 罗斯动物血红素过氧化物酶以H2 O2和Br-为底物产生HOBr。HOBr，一种化学表亲， 漂白剂（HOCl）是能够破坏蛋白质、脂质和核酸的强氧化剂，并且通常 促进组织损伤。 我们最近发现，细胞外基质（ECM）蛋白称为过氧化物酶（Pxdn）也 生成HOBr。Pxdn使用HOBr作为合成代谢的反应性中间体，以形成新型硫亚胺（S=N）交叉， IV型胶原是基底膜（BM）的主要成分，如肾小球BM（GBM）。在 在果蝇中，我们发现Pxdn和硫亚胺交联的缺失损害了基底膜， 组织完整性导致幼虫死亡。然而，Pxdn敲除（KO）小鼠是可行的，但证明了 降低硫亚胺交联和BM强度。基于这种表型，我们预期单侧输尿管 梗阻（UUO）和小管内压力增加将导致更大的管状BM拉伸， 在Pxdn KO小鼠中对肾小管细胞的机械应力。因此，Pxdn KO小鼠将表现出增加的 肾脏炎症和纤维化。巧合的是，Pxdn KO小鼠表现出较少的肾脏炎症， 纤维化与HOBr介导的氧化损伤减少。基于这些数据，我们假设Pxdn 通常使用HOBr交联胶原IV并支持组织完整性，但当失调时，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功能丧失是否能保护肾功能， 与肾小球和肾小管间质疾病相比，炎症程度和位置不同的损伤。 目的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， 包括使用质谱鉴定HOBr介导的蛋白质氧化修饰。在目标3中， 我们将机械地解决Pxdn如何使用HOBr交联胶原IV，但避免附带损害， 其他生物分子综上所述，该建议旨在确定HOBr在肾脏炎症中的新作用 和纤维化。这些研究希望合理的策略，目标HOBr治疗慢性肾脏疾病。

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.