DataSheet_2_Over-Expression of Inhibitor of Differentiation 2 Attenuates Post-Infarct Cardiac Fibrosis Through Inhibition of TGF-β1/Smad3/HIF-1α/IL-11 Signaling Pathway.docx

Background: Cardiac fibrosis after myocardial infarction mainly causes cardiac diastolic and systolic dysfunction, which results in fatal arrhythmias or even sudden death. Id2, a transcriptional repressor, has been shown to play an important role in the development of fibrosis in various organs, but its effects on cardiac fibrosis remain unclear. This study aimed to explore the effects of Id2 on cardiac fibrosis after myocardial infarction and its possible mechanisms.Methods: This study was performed in four experimental groups: control group, treatment group (including TGF-β1, hypoxia or MI), treatment+GFP group and treatment+Id2 group. In vitro anoxic and fibrotic models were established by subjecting CFs or NRVMs to a three-gas incubator or TGF-β1, respectively. An animal myocardial infarction model was established by ligating of the left anterior descending coronary artery followed by directly injecting of Id2 adenovirus into the myocardial infarct’s marginal zone.Results: The results showed that Id2 significantly improved cardiac EF and attenuated cardiac hypertrophy. The mRNA and protein levels of α-SMA, Collagen I, Collagen III, MMP2 and TIMP1 were higher in treatment+Id2 group than those in treatment group as well as in treatment+GFP group both in vivo and in vitro. Immunofluorescence revealed that both α-SMA and vimentin were co-expressed in the treatment group and GFP group, but the co-expression were not detected in the control group and Id2 group. Additionally, our findings illustrated that Id2 had protective effects demonstrated by its ability to inhibit the TGF-β1/Smad3/HIF-1α/IL-11 signaling pathways. Besides, over-expression of Id2 reduced cardiomyocytes apoptosis.Conclusion: In conclusion, this study demonstrated that over-expression of Id2 preserved cardiac function and ameliorated adverse cardiac remodeling, which might be a promising treatment target for cardiac fibrosis and apoptosis.

背景：心肌梗死后发生的心脏纤维化主要导致心脏舒张和收缩功能障碍，进而引发致命性心律失常或甚至猝死。Id2转录抑制因子已被证实在对多种器官纤维化发展中扮演着至关重要的角色，但其对心脏纤维化的影响尚不明确。本研究旨在探讨Id2在心肌梗死后心脏纤维化中的作用及其可能的机制。方法：本研究分为四组实验组：对照组、治疗组（包括TGF-β1、缺氧或MI）、治疗+GFP组以及治疗+Id2组。通过将成纤维细胞或新生儿大鼠心肌细胞（NRVMs）置于三气培养箱或TGF-β1中，建立了体外缺氧和纤维化模型。通过结扎左前降支冠状动脉并直接将Id2腺病毒注入心肌梗死边缘区域，建立了动物心肌梗死模型。结果：结果表明，Id2显著提高了心脏射血分数（EF）并减轻了心脏肥大。在体内和体外，治疗+Id2组中α-SMA、胶原蛋白I、胶原蛋白III、MMP2和TIMP1的mRNA和蛋白水平均高于治疗组和治疗+GFP组。免疫荧光显示，治疗组和GFP组中α-SMA和波形蛋白共表达，而在对照组和Id2组中未检测到共表达。此外，我们的研究结果表明，Id2通过抑制TGF-β1/Smad3/HIF-1α/IL-11信号通路表现出保护作用。此外，Id2过表达减少了心肌细胞凋亡。结论：综上所述，本研究证实了Id2过表达可维持心脏功能并改善不良的心脏重构，这可能是治疗心脏纤维化和细胞凋亡的潜在治疗靶点。