Instigation of Glomerular Injury by Inflammasomes in Obesity: Beyond Inflammation

 描述(由申请人提供)：据报道，肥胖与肾小球损伤和终末期肾脏疾病(ESRD)有关。尽管肥胖合并高血压或糖尿病可能参与终末期肾病的发生发展，但肥胖所致肾损害的分子机制，尤其是高血压和糖尿病之前肾小球损伤的早期机制尚不清楚。在这项拨款提案中，我们试图阐明一个早期的细胞内分子机制，即NALP3炎症小体激活，它可能通过其炎症或非炎症途径启动肾小球损伤，导致肾小球功能障碍，并最终在肥胖时导致硬化。有趣的是，我们的初步研究表明，肥胖诱导的NALP3炎性小体激活，并独立于动脉血压升高而促进肾小球损伤，并且还表明，除了炎症之外，激活的炎性小体对足细胞有直接作用。这可能代表了炎症以外的炎性小体激活的一种新的致病机制。基于这些观察，我们假设肥胖增加内脂素的产生，从而激活足细胞中的NALP3炎性小体，产生IL-1，刺激肾小球的炎症反应，启动直接的足细胞损伤，最终导致肾小球损伤和硬化。为了验证这一假设，我们将首先确定肥胖诱导的NALP3炎症体的形成和激活是否有助于实验性高脂饮食(HFD)诱导的肥胖之前的肾小球损伤，使用带有或不带有ASC基因的ASC-/-小鼠以及具有和不具有局部沉默ASC基因的野生型小鼠。然后，我们将研究NALP3炎症体是如何在足细胞中被激活的，重点是脂肪因子内脂素在培养的足细胞和小鼠体内的作用，并阐明其在炎症体激活中的功能意义。最后，我们将通过研究炎症小体产物如IL-1？、IL-18、炎性小体下垂和湿气在培养的足细胞和HFD诱导的肥胖小鼠中的作用，来探讨激活的NALP3炎性小体导致足细胞损伤和肾小球功能障碍或硬化的机制。这项拟议研究的结果将为针对炎性小体开发新的治疗策略提供新的机制见解，以治疗和预防肥胖症患者的终末期肾病。

 DESCRIPTION (provided by applicant): Obesity has been reported to be associated with glomerular injury and ultimate end-stage renal disease (ESRD). Although hypertension or diabetes mellitus in obesity may contribute to the development of ESRD, the molecular mechanisms of obesity-induced renal injury, in particular, the early mechanisms mediating glomerular injury that occur prior to hypertension and diabetes are still poorly understood. In thi grant proposal, we attempt to elucidate an early intracellular molecular mechanism, namely, the Nalp3 inflammasome activation, which may switch on glomerular injury through its inflammatory or non-inflammatory pathway leading to glomerular dysfunction and ultimately sclerosis during obesity. Interestingly, our preliminary studies demonstrated that obesity-induces the Nalp3 inflammasome activation and contributes to the glomerular injury independent of elevated arterial blood pressure and have also shown that beyond inflammation, the activated inflammasomes have direct actions on the podocytes. This may represent a novel pathogenic mechanism of inflammasome activation beyond inflammation. Based on these observations, we hypothesize that obesity increases visfatin production and thereby activates Nalp3 inflammasomes in podocytes to produce IL-1ß stimulating inflammatory response in glomeruli and initiating direct podocyte damage, ultimately resulting in glomerular injury and sclerosis. To test this hypothesis, we will first determine whether obesity-induced Nalp3 inflammasome formation and activation contribute to glomerular injury in vivo prior to hypertension in experimental high fat diet (HFD)-induced obesity using Asc-/- mice with or without rescuing Asc gene and wild type mice with and without locally silencing Asc gene. We will then examine how Nalp3 inflammasomes are activated in podocytes with a focus on the role of adipokine visfatin in cultured podocytes and in vivo in mice and to elucidate its functional significance in inflammasome activation. Finally, we will explore the mechanisms by which activated Nalp3 inflammasomes lead to podocyte injury and glomerular dysfunction or sclerosis by studying the actions of inflammasome products such as IL-1ß, IL-18, pyroptosis and DAMPs in cultured podocytes and in mice with obesity induced by HFD. The findings from the proposed studies will provide new mechanistic insights for targeting inflammasomes to develop novel therapeutic strategies for treatment and prevention of ESRD in obese patients.