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

脂联素（APN）是一种主要由脂肪细胞产生的细胞因子，但也在心脏中表达，并大量存在于人血浆中。该项目在CRC Transregio 19的第二个资助期启动，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，具有高APN水平的DCMi患者在随访时表现出显著减少的炎症和更好的结果。与这些发现一致，APN基因转移在患有自身免疫性心肌炎的小鼠中减少了限制心脏炎症的趋化因子和促炎细胞因子的表达。在心肌细胞和成纤维细胞中，APN抑制TLR 4依赖性炎症表型的表达。在T细胞中，APN被表征为抗原特异性细胞因子应答和增殖的负调节剂。以类似的方式，已经确定了APN在体外和体内对NK细胞功能的抑制。总之，我们的数据表明APN作为先天性和适应性免疫的负调节剂发挥作用，并抑制DCM i/心肌炎的炎症过程，从而改善预后。此外，在体外小鼠和人类的数据提供的证据APN通过调节MMP-9的表达直接参与心脏重塑。这些数据表明，APN上调是一种有前途的治疗方法，以改善心血管炎症。重要的是，我们可以确定叉头转录因子FOXO 3a作为APN表达的主要调节因子。到目前为止，人们对FOXO 3a功能在心血管系统中的调节作用知之甚少。我们以前已经表明，Foxo 3a抑制心肌细胞的肥大反应，初步数据表明Foxo 3a参与心脏重塑和氧化还原解毒。此外，Foxo 3a目前正在研究其在先天性和适应性免疫应答中的调节作用。FOXO 3a在心血管炎症以及心脏重塑过程中的功能表征是本提案的目标（最初提交给CRC/TR 19的第3个资助期）。将在体外和几种心脏炎症和损伤的体内小鼠模型中分析FOXO 3a调节的作用。在心肌病患者中，急性MI和心脏同种异体移植物排斥FOXO 3a表达/激活状态以及FOXO 3a多态性将与免疫和结果参数相关。最后，将在鼠动物模型中研究FOXO 3a的治疗性调节对免疫应答以及心脏重塑的影响。由于脂联素靶向治疗目前尚不可行，但FOXO 3a功能的调节剂目前正在肿瘤学中开发，因此这种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.