Characterization of Cardioprotection and Immunmodulation by FOXO3a as a Master Regulator of Adiponectin

脂联素（Adiponectin， APN）是一种主要由脂肪细胞产生的细胞因子，在心脏中也有表达，并大量存在于人血浆中。本项目启动于CRC Transregio 19第二期资助期，旨在研究APN在体外、病毒性和自身免疫性心肌炎小鼠模型以及DCMi患者中的心脏保护和免疫调节作用。DCMi患者心脏和全身APN表达升高。值得注意的是，高APN水平的DCMi患者在随访中表现出明显减少的炎症和更好的预后。与这些发现一致，APN基因在自身免疫性心肌炎小鼠中的转移减少了趋化因子和促炎细胞因子的表达，限制了心脏炎症。在心肌细胞和成纤维细胞中，APN抑制TLR4依赖性炎症表型的表达。在T细胞中，APN被认为是抗原特异性细胞因子反应和增殖的负调节因子。以类似的方式，在体外和体内已经确定了APN对NK细胞功能的抑制作用。总之，我们的数据表明APN作为先天免疫和适应性免疫的负调节因子，抑制DCMi/心肌炎的炎症过程，从而改善预后。此外，体外小鼠和人体数据提供了APN通过调节MMP-9表达直接参与心脏重塑的证据。这些数据表明，APN上调是一种有希望改善心血管炎症的治疗方法。重要的是，我们可以确定叉头转录因子FOXO3a是APN表达的主要调控因子。到目前为止，人们对FOXO3a功能调节在心血管系统中的作用知之甚少。我们之前已经证明Foxo3a抑制心肌细胞的肥厚反应，初步数据表明Foxo3a参与心脏重塑和氧化还原解毒。此外，Foxo3a在先天和适应性免疫反应中的调节作用目前正在研究中。FOXO3a在心血管炎症和心脏重塑过程中的功能表征是本提案的目标（最初提交于CRC/TR19的第三个资助期）。FOXO3a调节的作用将在体外和几种体内小鼠心脏炎症和损伤模型中进行分析。在心肌病患者中，急性心肌梗死和心脏异体移植排斥反应FOXO3a的表达/激活状态以及FOXO3a多态性将与免疫和预后参数相关。最后，我们将在小鼠动物模型中研究FOXO3a治疗性调节对免疫反应和心脏重构的影响。由于脂联素靶向治疗目前尚不可行，但FOXO3a功能调节剂目前正在肿瘤学中开发，因此该方法具有很高的临床转化潜力。

Adiponectin (APN) is a cytokine mainly produced by adipocytes but also expressed in the heart and abundantly present in human plasma. This project has been initiated during the 2nd funding period of the CRC Transregio 19 to study cardioprotective and immunmodulatory effects of APN in vitro, in viral and autoimmune myocarditis mouse models as well as in DCMi patients. DCMi patients showed elevated cardiac and systemic APN expression. Remarkably, DCMi patients with high APN levels exhibited significantly decreased inflammation and better outcome at follow-up. In line with these findings, APN gene transfer in mice with autoimmune myocarditis diminished the expression of chemokines and pro-inflammatory cytokines confining cardiac inflammation. In cardiac myocytes and fibroblasts APN inhibited the expression of a TLR4 dependent inflammatory phenotype. In T cells, APN was characterized as a negative regulator of antigen-specific cytokine response and proliferation. In a similar manner, inhibition of NK cell function by APN in vitro and in vivo has been determined. In conclusion our data implicate that APN functions as a negative regulator of innate and adaptive immunity and inhibits the inflammatory process in DCMi/myocarditis resulting in improved outcome. Furthermore, in vitro murine and human data provide evidence of APN being directly involved in cardiac remodeling by regulating MMP-9 expression. These data suggest that APN up-regulation is a promising therapeutic approach to ameliorate cardiovascular inflammation. Importantly, we could identify the Forkhead transcription factor FOXO3a as a master regulator of APN expression. Little is known so far about the effects of modulation of FOXO3a function in the cardiovascular system. We have previously shown that Foxo3a inhibits the hypertrophic response in cardiac myocytes and preliminary data suggest involvement of Foxo3a in cardiac remodeling and Redox-detoxification. Moreover, Foxo3a is currently studied for its regulatory role in innate and adaptive immune responses. The characterization of FOXO3a function in cardiovascular inflammatory as well as cardiac remodeling processes is the objective of this proposal (originally submitted for the 3rd funding period within the CRC/TR19). Effects of FOXO3a modulation will be analyzed in vitro and in several in vivo mouse models of cardiac inflammation and injury. In patients with cardiomyopathy, acute MI and cardiac allograft rejection FOXO3a expression/activation status as well as FOXO3a polymorphisms will be correlated with immune and outcome parameters. Finally, the impact of therapeutic modulation of FOXO3a on the immune response as well as cardiac remodeling will be studied in murine animal models. Since adiponectin targeting therapies are presently not feasible but modulators of FOXO3a function are currently being developed in oncology, this approach has a high potential for clinical translation.