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 泌尿系统泌尿道感染（UTI）在患有尿路感染的人中更常见，更严重，结局更差。 糖尿病迄今为止，糖尿病患者易患UTI的机制尚未阐明。该项目将 评估胰岛素如何调节肾脏闰细胞的先天免疫机制。超越证据 我们的研究小组和其他人认为，嵌入细胞（IC）在抗菌防御中起着关键作用， 肾盂肾炎大肠大肠杆菌（UPEC）。我们的研究表明，胰岛素抵抗和2型糖尿病会增加UTI的风险。 当胰岛素受体在小鼠IC中选择性缺失时，体内UPEC易感性显著增加。还有， 我们已经证明胰岛素诱导人原代肾上皮细胞抗菌肽（AMP）表达 通过磷脂酰肌醇3-激酶（PI 3 K/AKT）信号通路。具体来说，我们的数据表明，胰岛素诱导 核糖核酸酶7（RNase 7）的产生，是人类泌尿道中最有效的AMP，可以保护泌尿系统免受 UPEC。总之，这些数据为我们的假设提供了强有力的支持，即胰岛素信号传导在胰岛素抵抗中起着重要作用。 通过调节PI 3 K/AKT活性和下游AMP产生的先天IC防御。在这些以前的基础上 研究，我们提出了一个全面的分析胰岛素的能力，调节IC防御机制。目标1将评估 胰岛素抵抗和2型糖尿病如何影响IC抗菌防御。目标2将确定如何IC胰岛素 受体缺失影响AMP转录以及靶向的PI 3 K/AKT活化是否诱导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 RNA酶7的产生及其体内抗微生物活性。该项目的长期目标是改善护理 糖尿病患者的UTI通过确定新的治疗选择。通过评估胰岛素信号在宿主中的作用， 防御，完成这些目标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 胰岛素信号传导靶点，如PI 3 K/AKT和RNase 7，作为预防UTI的新疗法， 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.