Role of the Interleukin12/STAT4 Pathway in Insulin Resistance and Atherosclerosis

描述（由申请方提供）：有证据表明，在内脏脂肪组织（AT）增加相关状态下，免疫细胞活化与胰岛素抵抗（IR）之间存在重要联系。细胞因子的白细胞介素-12（IL-12）家族鉴于其在细胞介导的免疫应答和下游炎性基因诱导中的重要性而特别相关。IL-12已被证明直接参与动脉粥样硬化的进展。信号转导子和转录激活子4（STAT 4）由IL-12激活，诱导与动脉粥样硬化和代谢综合征中的炎症相关的几个主要基因的表达。中心假设是IL-12/Stat-4通路在内脏和主动脉周围脂肪组织中诱导IR中起关键作用，这将影响动脉粥样硬化中的免疫应答并进一步加速动脉粥样硬化。解决这一问题的目标包括：目标1。确定造血细胞和非造血细胞中IL-12/STAT 4缺陷对肥胖诱导的胰岛素抵抗和脂肪组织炎症的保护作用机制。我们的假设是，STAT 4缺乏通过改变脂肪组织中T细胞丰度和表型以及巨噬细胞极化，以及通过减少内脏脂肪细胞中的炎症和改善胰岛素敏感性来预防饮食诱导的肥胖中的IR。目标1.1：确定IL-12或STAT 4缺陷在造血（T细胞，NK细胞）相对于非造血区室（脂肪细胞）中对IR和肥胖症的发展的体内影响。目标1.2：确定IL-12/STAT 4缺乏对脂肪组织中的体内和体外T细胞迁移、T细胞和巨噬细胞表型以及促炎细胞因子的极化和产生的作用。目标1.3：机制研究IL-12/STAT 4缺陷在脂肪细胞中对葡萄糖摄取和胰岛素信号传导的功能作用，以响应高脂饮食和细胞因子刺激。目标2.确定IL-12/Stat-4通路抑制对AT炎症相关动脉粥样硬化的影响。主动脉周围和内脏AT在脂肪组织相关动脉粥样硬化中的具体作用是什么？目标2.1：在喂食致糖尿病饮食（DD）以诱导IR和喂食含额外胆固醇的DD（DDC）以诱导动脉粥样硬化和AT炎症的Stat-4-/- Ldlr-/-小鼠中，检查Stat-4缺乏对伴和不伴AT炎症的动脉粥样硬化的影响。目的2.2：测试AT炎症、Stat-4缺乏对白细胞募集到主动脉周围、内脏AT和动脉瘤中的影响。目标2.3：确定AT炎症、Stat-4缺陷以及AT炎症相关动脉粥样硬化形成的条件对主动脉周围、内脏AT和动脉粥样硬化局部免疫反应的影响。目标2.4：研究IL-12抑制对喂食DDC饮食的小鼠中AT-炎症加速动脉粥样硬化的Stat-4+/+和Stat-4缺陷模型的作用和特异性。已完成的项目应确定一个创新的治疗目标，可能导致新的治疗，以减少与中心性肥胖，胰岛素抵抗和糖尿病相关的动脉粥样硬化。

DESCRIPTION (provided by applicant): Evidence suggests an important link between immune cell activation and insulin resistance (IR) in states associated with increases in visceral adipose tissue (AT). The interleukin-12 (IL-12) family of cytokines is particularly relevant given their importance in cell-mediated immune responses and downstream inflammatory gene induction. IL-12 has been shown to be directly involved in the progression of atherosclerosis. Signal transducer and activator of transcription 4 (STAT4), which is activated by IL-12, induces the expression of several major genes linked to inflammation in atherosclerosis and the metabolic syndrome. The central hypothesis is that IL-12/Stat-4 pathway plays a critical role in the induction of IR in visceral and peri-aortic adipose tissue and this will affect the immune response in aortas and further accelerate atherosclerosis. Aims to address this include: Aim 1. Determine mechanisms related to IL-12/STAT4 deficiency in hematopoetic and non-hematopoetic cells on protection against obesity induced insulin resistance, and adipose tissue inflammation. Our hypothesis is that STAT4 deficiency prevents IR in diet-induced obesity by changes in T cell abundance and phenotype and macrophage polarization in adipose tissue and by reducing inflammation and improving insulin sensitivity in visceral adipocytes. Aim 1.1: Determine the in vivo effect of IL-12 or STAT4 deficiency in the hematopoietic (T cells, NK cells) vs. non-hematopoetic compartment (adipocyte) for the development of IR and obesity. Aim 1.2: Determine role of IL-12/STAT4 deficiency on in vivo and in vitro T cell migration in adipose tissue, T cell and macrophage phenotype and polarization and production of pro-inflammatory cytokines. Aim 1.3: Mechanistically investigate functional roles of IL-12/STAT4 deficiency in adipocytes on glucose uptake and insulin signaling in response to high fat diet and cytokine stimulation. Aim 2. Determine effects of IL-12/Stat-4 pathway inhibition on AT inflammation-associated atherosclerosis. What is the specific role of peri-aortic and visceral AT in adipose tissue-related atherosclerosis? Aim 2.1: Examine effects of Stat-4 deficiency on atherosclerosis with and without AT inflammation in Stat -4-/- Ldlr-/- mice fed a diabetogenic diet (DD) to induce IR and DD with additional cholesterol (DDC) to induce atherosclerosis and AT inflammation. Aim 2.2: Test the effects of AT inflammation, Stat-4 deficiency on leukocyte recruitment into peri-aortic, visceral AT and aortas. Aim 2.3: Determine the involvement of AT inflammation, Stat-4 deficiency and the conditions of AT inflammation-related atherogenesis on local immune response in peri-aortic, visceral AT and aortas. Aim 2.4: Investigate effects and specificity of IL-12 inhibition on Stat-4+/+ and Stat-4 deficient model of AT- inflammation accelerated atherosclerosis in mice fed DDC diet. The completed project should identify an innovative therapeutic target that could lead to new treatment to reduce atherosclerosis associated with central obesity insulin resistance and diabetes.