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

脂联素(APN)是一种细胞因子，主要由脂肪细胞产生，但也在心脏表达，并在人体血浆中大量存在。这个项目是在CRC TransRegio 19的第二个资助期启动的，目的是研究APN在体外、在病毒性心肌炎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，APN水平高的DCMI患者在随访时炎症显著减轻，结果更好。与这些发现一致的是，自身免疫性心肌炎小鼠的APN基因转移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抑制依赖TLR4的炎症表型的表达。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。以同样的方式，测定了APN在体外和体内对NK细胞功能的抑制作用。综上所述，我们的数据暗示APN作为先天免疫和获得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，在体外，小鼠和人类的数据提供了APN通过调节基质金属蛋白酶-9的表达直接参与心脏重塑的证据。这些数据表明，上调APN是一种有前景的改善心血管炎症的治疗方法。重要的是，我们可以确定Forkhead转录因子FOXO3a是APN表达的主要调节因子。到目前为止，对FOXO3a功能调节在心血管系统中的影响知之甚少。我们先前已经证明Foxo3a抑制心肌细胞的肥大反应，初步数据表明Foxo3a参与心脏重构和氧化还原解毒。此外，Foxo3a目前因其在先天性和获得性免疫反应中的调节作用而被研究。FOXO3a在心血管炎症和心脏重塑过程中的功能特征是这项提案的目标(最初是在CRC/TR19中的第三个资助期提交的)。FOXO3a的调节作用将在体外和几种心脏炎症和损伤的体内小鼠模型中进行分析。在心肌病患者中，急性心肌梗死和心脏移植排斥反应FOXO3a表达/激活状态以及FOXO3a基因多态性将与免疫和预后参数相关。最后，将在小鼠动物模型中研究FOXO3a的治疗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功能的调节剂目前正在肿瘤学中开发，该方法具有很高的临床翻译潜力。

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.