Pathogenesis of chronic renal injury and hypertension in HIV-infected children

 描述（由申请人提供）：目前全世界感染HIV-1的350万儿童中，许多人预计将进入成年并发展为慢性肾脏疾病（CKD）。关于HIV-1如何在这些儿童中引起慢性肾损伤知之甚少，我们的儿科HIV项目目前处于解决这一问题的独特地位。最近，我们发现TNF-α通过不依赖于CD4的跨膜TNF-α包膜介导的机制促进培养足细胞和人肾小球内皮细胞（HGEc）的低水平生产性感染的建立，并与非洲血统人群中与CKD和高血压（HTN）相关的ApoL-1风险等位基因的上调表达相关。此外，我们发现：（i）当暴露于成纤维细胞生长因子-2（FGF-2）时，由HIV-1和肿瘤坏死因子-α（TNF-α）"引发"的足细胞和HGEc经历反常的凋亡或细胞死亡;（ii）表达HIV-1基因的足细胞和Nef单独分泌损害HGEc血管生成行为和存活的分子;（iii）从患有HIV-肾病（HIV-RD）的儿童分离的肾小管上皮细胞和巨噬细胞分泌FGF结合蛋白（FGF-BP-1），其增强血管紧张素II（Ang II）的血管活性并在小鼠中引起HTN;和（iv）单独或与FGF-2组合的HIV-Tat在HIV-Tg26小鼠中促进CKD和肾小管盐消耗病症的发展。基于这些发现，我们假设HIV-1和TNF-α在暴露于FGF-2时损害肾上皮细胞和HGEc存活或再生的能力，影响肾小球毛细血管的再生，并促进CKD和HTN的发展。在目标1中，我们将确定当暴露于FGF-2时，HIV-1和TNF-α是否"引发"成熟足细胞和HGEc发生凋亡或细胞死亡，并确定足细胞前体是否对HIV感染更具抵抗力，对TNF-α + FGF-2介导的细胞死亡较不敏感。在目标2中，我们将定义表达HIV基因的足细胞分泌的因子或单独的Nef如何影响HGEc的血管生成行为，并确定参与该过程的最相关的信号通路和可溶性因子。在目标3中，我们将检验HIV-1可通过血管平滑肌细胞中慢性内皮损伤和收缩性变化的诱导，经由涉及FGF-BP-1、FGF-2和Rho-A活化的Ang II介导的机制，引起HTN的假设。在这里，我们将使用Tat诱导的HIV-Tg26来确定HIV-1基因是否损害肾小管中Ang II受体的表达，并诱导盐消耗障碍，从而延迟HIVAN患者HTN的发作。这项研究将填补我们对儿童HIV-RD知识的一个独特空白，并确定HIV-1如何影响足细胞和HGEc之间的双向串扰，从而促进CKD和HTN的发展。

 DESCRIPTION (provided by applicant): Many of the 3.5 million children currently infected with HIV-1 worldwide are expected to reach adulthood and develop chronic kidney disease (CKD). Very little is known about how HIV-1 induces chronic renal injury in these children, and our pediatric HIV-program is currently in a unique position to address this problem. Recently we found that TNF-α facilitates the establishment of a low level productive infection of cultured podocytes and human glomerular endothelial cells (HGEc) through a trans-membrane TNF-α-envelope- mediated mechanism that is independent of CD4, and is associated with an up-regulated expression of the ApoL-1 risk alleles that are associated with CKD and hypertension (HTN) in people of African ancestry. Furthermore, we found that (i) podocytes and HGEc that are "primed" by HIV-1 and Tumor Necrosis Factor -α (TNF-α) undergo paradoxical apoptosis or cell death when exposed to Fibroblast Growth Factor-2 (FGF-2); (ii) podocytes expressing HIV-1 genes, and Nef alone, secrete molecules that impair the angiogenic behavior and survival of HGEc; (iii) Renal tubular epithelial cells and macrophages isolated from children with HIV- renal diseases (HIV-RD) secrete an FGF binding protein (FGF-BP-1) that enhances the vascular activity of Angiotensin II (Ang II) and causes HTN in mice; and (iv) HIV-Tat, alone or in combination with FGF-2, precipitates the development of CKD and tubular salt wasting disorders in HIV-Tg26 mice. Based on these findings, we hypothesize that HIV-1 and TNF-α impair the ability of renal epithelial cells and HGEc to survive or regenerate when exposed to FGF-2, affecting the regeneration of glomerular capillaries, and precipitating the development of CKD and HTN. In aim 1, we will define whether HIV-1 and TNF-α "prime" mature podocytes and HGEc to undergo apoptosis or cell death when exposed to FGF-2, and define whether podocyte precursors are more resistant to HIV-infection and less susceptible to TNF-α + FGF-2 mediated cell death. In aim 2 we will define how factors secreted by podocytes expressing HIV-genes, or Nef alone, affect the angiogenic behavior of HGEc, and identify the most relevant signaling pathways and soluble factors involved in this process. In aim 3 we will test the hypothesis that HIV-1 can cause HTN through the induction of chronic endothelial injury and contractility changes in vascular smooth muscle cells, via an Ang II- mediated mechanism that involves FGF-BP-1, FGF-2 and Rho-A activation. Here, we will use Tat-inducible HIV-Tg26 to determine whether HIV-1 genes impair the expression of Ang II receptors in renal tubules and induce a salt wasting disorder that delays the onset of HTN in patients with HIVAN. This study will fill a unique gap in our knowledge of childhood HIV-RD, and define how HIV-1 affects the bidirectional crosstalk between podocytes and HGEc precipitating the development of CKD and HTN.