Linking Insulin Signaling to Antimicrobial Peptide Production and the Kidney's Antibacterial Defenses

摘要 糖尿病是一种增加感染易感性的全身性疾病。最常见的感染部位是 尿路。尿路感染(UTI)在以下人群中更常见、更严重、预后更差 糖尿病。到目前为止，糖尿病患者易患尿路感染的机制尚未阐明。这个项目将 评估胰岛素如何调节肾脏嵌入细胞中的先天免疫机制。超越……的证据 我们的研究小组和其他人认为，间质细胞(IC)在抗菌防御中发挥着关键作用 尿路致病性大肠杆菌(UPEC)。我们的研究表明，胰岛素抵抗和2型糖尿病会增加尿路感染的风险。 当胰岛素受体在小鼠ICs中选择性缺失时，UPEC在体内的易感性显著增加。另外， 我们已经证明胰岛素诱导原代人肾上皮细胞表达抗菌肽(AMP)。 通过磷脂酰肌醇3-激酶(PI3K/AKT)信号通路。具体地说，我们的数据显示，胰岛素能诱导 产生核糖核酸酶7(RNase7)，人类尿路中最有效的AMP，保护尿路上皮免受 UPEC。总之，这些数据为我们的假设提供了强有力的支持，即胰岛素信号在 通过调节PI3K/AKT的活性和下游AMP的产生来实现天然的IC防御。建立在这些以前的基础上 研究中，我们建议对胰岛素调节IC防御机制的能力进行全面分析。目标1将评估 胰岛素抵抗和2型糖尿病如何影响IC的抗菌防御。目标2将确定IC胰岛素是如何 受体缺失影响AMP转录，以及靶向PI3K/AKT激活是否诱导AMP表达。目标3 将使用一种新的转基因人源化小鼠模型来评估胰岛素抵抗和胰岛素治疗如何影响 核糖核酸酶7的生产及其体内抗菌活性。这个项目的长期目标是改善护理 通过确定新的治疗方案来评估糖尿病患者的尿路感染。通过评估胰岛素信号在宿主中的作用 防御，这些目标的完成可以对糖尿病患者的健康产生深远的影响，因为他们可能会发展 胰岛素信号靶点，如PI3K/AKT和RNase7，作为预防尿路感染的新疗法，延长尿路感染的治疗 抗生素范围之外的选择。

ABSTRACT Diabetes mellitus is a systemic disorder that increases infection susceptibility. The most common site of infection is the urinary tract. Urinary tract infection (UTI) is more common, more severe, and has worse outcomes in people with diabetes. To date, the mechanisms that predispose people with diabetes to UTI have not been elucidated. This project will evaluate how insulin regulates innate immune mechanisms in the kidney’s intercalated cells. Surmounting evidence from our research group and others suggests that intercalated cells (IC) play a critical role in antibacterial defenses against uropathogenic E. coli (UPEC). Our research shows that insulin resistance and Type 2 diabetes mellitus increases UTI risk. When the insulin receptor is selectively deleted in murine ICs, UPEC susceptibility significantly increases in vivo. Also, we have demonstrated that insulin induces antimicrobial peptide (AMP) expression in primary human renal epithelial cells via the phosphatidylinositide 3-kinase (PI3K/AKT) signaling pathway. Specifically, our data show that insulin induces Ribonuclease 7 (RNase 7) production, the most potent AMP in the human urinary tract, to shield the urothelium from UPEC. Together, these data provide strong support for our hypothesis that insulin signaling plays an essential role in innate IC defenses by regulating PI3K/AKT activity and downstream AMP production. Building on these previous studies, we propose a comprehensive analysis of insulin’s ability to regulate IC defense mechanisms. Aim 1 will evaluate how insulin resistance and Type 2 diabetes mellitus affects IC antibacterial defenses. Aim 2 will identify how IC insulin receptor deletion impacts AMP transcription and whether targeted PI3K/AKT activation induces AMP expression. Aim 3 will use a novel transgenic humanized mouse model to assess how insulin resistance and insulin therapy impacts the production of RNase 7 and its antimicrobial activity in vivo. The long-term objective of this project is to improve the care of diabetic patients with UTI by identifying novel therapeutic options. By evaluating the role of insulin signaling in host defense, completion of these Aims can have profound influence on the health of people with diabetes as they may develop insulin-signaling targets, like PI3K/AKT and RNase 7, as new therapeutics that prevent UTI, extending UTI treatment options beyond the scope of antibiotics.