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

项目总结/摘要 常染色体显性遗传性多囊肾病（ADPKD）是一种遗传性疾病，其特征是存在 许多充满液体的囊肿，间质性炎症和纤维化导致肾脏功能进行性下降， 功能新出现的证据表明，尿磷酸盐（Pi）促进膀胱生成，激活先天性 免疫反应。在以前的研究中，高磷饮食显示出增加肾脏钙磷沉积， 在非正向啮齿类动物ADPKD模型中， 减缓疾病进展。ADPKD中持续的囊肿生长导致功能性肾单位的丧失， 未受影响的肾单位的代偿性超滤增加单个肾单位的Pi排泄以保护Pi 平衡小管内过饱和的Pi水平可导致CaPi纳米晶体的形成，其导致小管内的钙离子浓度升高。 损伤和炎症反应。最近，Toll样受体4（TLR 4），先天免疫的关键组成部分， 已被认为介导高尿Pi诱导的NF-κB活化和肾小管损伤;然而， TLR 4在高Pi诱导的PKD加速中作为主要介质的作用尚未研究。Resolvins，一个家庭 内源性脂质衍生物，通过抑制NF-κB和减少NF-κB的表达， 巨噬细胞吞噬作用增强导致肾矿物晶体沉积。目前，治疗效果 在PKD中尚未评价消退素的作用。在初步研究中，人类ADPKD肾脏 与正常人肾脏相比，囊性衬里细胞中存在晶体沉积和更高的TLR 4表达。 用CaPi纳米晶体孵育人ADPKD细胞增加TNF-α mRNA，表明CaPi纳米晶体 刺激TLR 4/NF-κB信号通路。将Pkd 1 RC/RC小鼠，一种正向ADPKD模型，用 高Pi饮食加速囊肿生长，并增加损伤、炎症和纤维化标志物。我们还发现 短期给予消退素D1减少了炎症标志物包括TNF-α的肾表达， IL-1β和MCP-1。因此，我们假设高尿Pi导致TLR 4/NF-κB- ADPKD中依赖性先天免疫应答和使用消退素抑制NF-κB减轻疾病 进展本实验将确定：（1）TLR 4在高膳食营养素影响中的作用 Pi对囊肿形成的影响，以及（2）使用消退素抑制先天免疫应答是否可以预防PKD进展。 PI将与研究副总裁办公室密切合作，并与战略协调， 由负责多元化和包容性的副总裁领导，制定并实施一项强有力的招聘计划， 多样化的本科生。PI在培训方面具有极大的热情和成功的经验 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参加生物医学研究，（2）奠定基础， PI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.