High Urinary Phosphate Induces TLR4-mediated Inflammation and Cystogenesis in Polycystic Kidney Disease

项目摘要/摘要 常染色体显性遗传多囊肾病(ADPKD)是一种遗传性疾病，其特征是 大量充满液体的囊肿、间质炎症和纤维化导致肾脏进行性衰退 功能。新的证据表明，尿磷(PI)促进了膀胱的发生并激活了先天的 免疫反应。在以前的研究中，高等电点饮食被证明增加了肾脏Capi纳米晶的沉积。 并在ADPKD的非同源啮齿动物模型中加速了包囊的生长；而限制猪的饮食 延缓疾病的发展。ADPKD的持续囊性生长导致功能性肾单位的丧失和 未受影响肾单位代偿性超滤增加单个肾单位PI排泄量以保存猪 平衡。过饱和的肾小管内PI水平可导致CaPI纳米晶体的形成，从而导致肾小管 损伤和炎症反应。近年来，天然免疫的关键成分--Toll样受体4(Toll-like Receptor 4，TLR4)被认为是天然免疫的重要组成部分，Toll样受体4是天然免疫的重要组成部分。 已被认为介导高尿PI诱导的NF-κB激活和肾小管损伤；然而，其作用 TLR4在高PI诱导的PKD加速中起主要中介作用的研究尚未见报道。决心，一个家庭 内源性脂衍生物通过抑制核因子-κB抑制损伤后的先天免疫反应并降低 巨噬细胞吞噬功能增强所致的肾脏矿物晶体沉积。目前，其治疗效果 还没有在PKD中进行评估。在初步研究中，人类ADPKD肾脏已经升高 与正常人肾脏相比，囊性衬里细胞中晶体沉积和TLR4表达增加。 人ADPKD细胞与CAPI纳米晶孵育后肿瘤坏死因子-α基因表达增加提示CAPI纳米晶存在 激活TLR4/NF-κB信号通路。用一种同源ADPKD模型攻击Pkd1RC/RC小鼠 高PI饮食加速了囊泡生长，增加了损伤、炎症和纤维化标记物。我们还发现， 短期给药可降低肾组织炎症标志物的表达，包括肿瘤坏死因子-α， Pkd1RC/RC小鼠IL-1β和单核细胞趋化蛋白1。因此，我们假设高尿PI导致TLR4/NF-κB- ADPKD依赖的先天免疫反应，以及用溶血素抑制NF-κB可减轻疾病 进步。拟议的实验将确定：(1)TLR4在调节高饮食效应中的作用 PI在膀胱发生中的作用，以及(2)如果使用溶血素抑制先天免疫反应可以防止PKD的进展。 国际和平研究所将与负责研究的副总统办公室密切合作，并与战略协调。 由负责多样性和包容性的副总裁领导，以制定和实施一项强有力的招聘计划 不同的本科生。PI有极大的热情和成功的培训经验 本科生和研究生。这一建议将：(1)为本科生提供更多的机会 密歇根理工大学的学生将参与生物医学研究，(2)为 国际和平研究所未来对PKD领域的贡献，以及(3)通过引入 先天免疫和PKD。

PROJECT SUMMARY/ABSTRACT Autosomal dominant polycystic kidney disease (ADPKD) is a genetic disorder characterized by the presence of numerous fluid-filled cysts, interstitial inflammation, and fibrosis leading to a progressive decline in kidney function. Emerging evidence suggests that urinary phosphate (Pi) promotes cystogenesis and activates innate immune responses. In previous studies, a high Pi diet was shown to increase renal CaPi nanocrystal deposition and accelerated cyst growth in a non-orthologous rodent model of ADPKD; whereas the restriction of dietary Pi attenuated disease progression. Relentless cyst growth in ADPKD leads to the loss of functional nephrons and compensatory hyperfiltration of unaffected nephrons increases single nephron Pi excretion to preserve Pi balance. Supersaturated intratubular Pi levels can lead to the formation of CaPi nanocrystals that cause tubule damage and inflammatory responses. Recently, toll-like receptor 4 (TLR4), a key component of innate immunity, has been suggested to mediate high urinary Pi-induced NF-κB activation and tubule damage; however, the role of TLR4 as the primary mediator in high Pi-induced PKD acceleration has not been studied. Resolvins, a family of endogenous lipid derivatives, cease innate immune responses after injury through inhibiting NF-κB and reduce renal mineral crystal deposition by increasing phagocytosis of macrophages. Currently, the therapeutic effects of resolvins have not been evaluated in PKD. In preliminary studies, human ADPKD kidneys have elevated crystal deposition and higher TLR4 expression in cystic lining cells compared with normal human kidneys. Incubation of human ADPKD cells with CaPi nanocrystals increased TNF-α mRNA suggesting CaPi nanocrystals stimulate TLR4/NF-κB signaling pathway. Challenging Pkd1RC/RC mice, an orthologous ADPKD model, with a high Pi diet accelerated cyst growth and increased injury, inflammation, and fibrosis markers. We also found that short-term administration of resolvin D1 reduced the renal expression of inflammation markers including TNF-α, IL-1β, and MCP-1, in Pkd1RC/RC mice. Thus, we hypothesized that high urinary Pi leads to TLR4/NF-κB- dependent innate immune responses in ADPKD, and that inhibition of NF-κB using resolvins attenuates disease progression. The proposed experiments will determine: (1) the role of TLR4 in mediating the effect of high dietary Pi on cystogenesis, and (2) if inhibiting innate immune response using resolvins can prevent PKD progression. The PI will work closely with the Office of the Vice President for Research and in coordination with the strategies led by the Vice President for Diversity and Inclusion to develop and implement a robust recruitment plan for diverse undergraduate students. The PI has tremendous enthusiasm and successful experience in training undergraduate and graduate students. This proposal will: (1) provide more opportunities for undergraduate students at Michigan Technological University to participate in Biomedical Research, (2) lay the groundwork for the PI’s future contributions to the fields of PKD, and (3) diversify university research infrastructure by introducing innate immunity and PKD.