Roos Carolyn M, Zhang Bin, Hagler Michael A, Verzosa Grace C, Huang Runqing, Oehler Elise A, Arghami Arman, Miller Jordan D
Department of Surgery, Mayo Clinic, Rochester, MN, United States.
Department of Physiology and Biomedical Engineering, Mayo Clinic, Rochester, MN, United States.
Front Cardiovasc Med. 2021 Jun 24;8:694881. doi: 10.3389/fcvm.2021.694881. eCollection 2021.
While a small number of studies suggest that oxidative stress has an influential role in fibrocalcific aortic valve disease (FCAVD), the roles of specific antioxidant enzymes in progression of this disease remain poorly understood. Here, we focused on selectively altering mitochondrial-derived oxidative stress-which has been shown to alter progression of a myriad of age-associated diseases-on the progression of molecular and phenotypic drivers of FCAVD. We generated low-density lipoprotein receptor-deficient, Apolipoprotein B100-only mice (LA) that were either haploinsufficient for MnSOD ( ) or genetically overexpressing MnSOD ( ). After 6 months of Western diet feeding, mice underwent echocardiography to assess valvular and cardiac function and tissues were harvested. Quantitative-RT PCR, immunohistochemistry, and histopathology were used to measure changes in molecular pathways related to oxidative stress, calcification, and fibrosis. While reductions in MnSOD increased oxidative stress, there was not an overt phenotypic effect of MnSOD deficiency on valvular and cardiac function in mice. While markers of canonical bone morphogenetic protein signaling tended to increase in valve tissue from (e.g., p-SMAD1/5/8 and osterix), we did not observe statistically significant increases in osteogenic signaling. We did, however, observe highly significant reductions in expression of osteopontin, which were associated with significant increases in calcium burden in mice. Reciprocally, genetically increasing MnSOD did not preserve valve function in , but we did observe slight reductions in p-SMAD1/5/8 levels compared to their -transgenic littermates. Interestingly, overexpression of MnSOD dramatically increased expression of osteopontin in valve tissue from mice, but was not sufficient to attenuate calcium burden when compared to their littermates. Collectively, this study demonstrates that maintenance of mitochondrial antioxidant capacity is important in preventing accelerated disease progression in a mouse model of FCAVD, but that effectively altering mitochondrial antioxidant capacity as a monotherapeutic approach to slow key histopathological and molecular drivers of FCAVD remains biologically and therapeutically challenging.
虽然少数研究表明氧化应激在纤维钙化性主动脉瓣疾病（FCAVD）中起重要作用，但特定抗氧化酶在该疾病进展中的作用仍知之甚少。在此，我们聚焦于选择性改变线粒体衍生的氧化应激（已证明其可改变多种与年龄相关疾病的进展）对FCAVD分子和表型驱动因素进展的影响。我们构建了低密度脂蛋白受体缺陷、仅载脂蛋白B100的小鼠（LA），这些小鼠要么锰超氧化物歧化酶（MnSOD）单倍不足（ ），要么基因过度表达MnSOD（ ）。在给予西方饮食6个月后，对小鼠进行超声心动图检查以评估瓣膜和心脏功能，并采集组织。采用定量逆转录聚合酶链反应、免疫组织化学和组织病理学方法来测量与氧化应激、钙化和纤维化相关分子途径的变化。虽然MnSOD的减少会增加氧化应激，但MnSOD缺乏对 小鼠的瓣膜和心脏功能并没有明显的表型影响。虽然在 小鼠的瓣膜组织中，经典骨形态发生蛋白信号通路的标志物往往会增加（例如磷酸化SMAD1/5/8和osterix），但我们并未观察到成骨信号有统计学意义的增加。然而，我们确实观察到骨桥蛋白的表达显著降低，这与 小鼠钙负荷的显著增加有关。相反，基因增加MnSOD并不能在 小鼠中维持瓣膜功能，但与它们的 转基因同窝小鼠相比，我们确实观察到磷酸化SMAD1/5/8水平略有降低。有趣的是，MnSOD的过度表达显著增加了 小鼠瓣膜组织中骨桥蛋白的表达，但与它们的 同窝小鼠相比，并不足以减轻钙负荷。总的来说，这项研究表明，维持线粒体抗氧化能力对于预防FCAVD小鼠模型中疾病的加速进展很重要，但作为一种单一治疗方法有效改变线粒体抗氧化能力以减缓FCAVD的关键组织病理学和分子驱动因素在生物学和治疗学上仍然具有挑战性。
