Dissecting aortic aneurysm in Marfan syndrome is associated with losartan-sensitive transcriptomic modulation of aortic cells

To improve our limited understanding of the pathogenesis of thoracic aortic aneurysm (TAA) leading to acute aortic dissection, we used single-cell RNA sequencing to profile disease-relevant transcriptomic changes of aortic cell populations in a well-characterized mouse model of the most commonly diagnosed form of Marfan syndrome (MFS). As result,MFSmod were identified only in the aorta of Fbn1mgR/mgR mice. In situ hybridizations of diagnostic transcripts located MFSmod cells to the intima of Fbn1mgR/mgR aortas. Consistent with angiotensin II type I receptor (At1r) contribution to TAA development, MFSmod cells were absent in the aorta of Fbn1mgR/mgR mice treated with the At1r antagonist losartan. Altogether, our findings indicate that a discrete dynamic alteration of aortic cell identity is associated with dissecting TAA in MFS mice and increased risk of aortic dissection in MFS patients. Overall design: Hypomorphic Fbn1mgR/mgR mice were routinely backcrossed for 10 generation on the C57BL/6J background. Mutant mice and WT littermates were euthanized to harvest aortic specimens spanning from immediately above the aortic root to immediately before the brachiocephalic artery.Aortic tissues of each genotype and treatment were pooled together, cleaned, minced and digested to make single-cell suspensions, then immediately processed according to manufacturer's instructions.

为弥补我们对引发急性主动脉夹层的胸主动脉瘤（thoracic aortic aneurysm, TAA）发病机制的认知不足，本研究依托经充分表征的最常见临床确诊型马凡综合征（Marfan syndrome, MFS）小鼠模型，采用单细胞RNA测序（single-cell RNA sequencing）技术分析主动脉细胞群的疾病相关性转录组变化。
研究结果显示，马凡综合征特征性细胞亚群（MFSmod）仅在Fbn1^mgR/mgR小鼠的主动脉中被检出。通过对标志性转录本的原位杂交实验，可将MFSmod细胞定位于Fbn1^mgR/mgR小鼠主动脉的内膜层。鉴于血管紧张素II 1型受体（angiotensin II type I receptor, AT1R）在胸主动脉瘤发病中的作用，给予AT1R拮抗剂氯沙坦的Fbn1^mgR/mgR小鼠主动脉中未检出MFSmod细胞。
综上，本研究结果表明，主动脉细胞身份的离散动态改变与马凡综合征小鼠的夹层型胸主动脉瘤相关，同时也与马凡综合征患者的主动脉夹层发病风险升高有关。
实验设计：将低功能型Fbn1^mgR/mgR小鼠在C57BL/6J遗传背景上连续回交10代以构建稳定模型。对突变型小鼠及其野生型（wild type, WT）同窝仔鼠实施安乐死，采集从主动脉根部上方至头臂动脉起始处之前的主动脉标本。将不同基因型及处理组的主动脉组织混合后，经清洗、剪碎、酶消化制备单细胞悬液，随后严格按照试剂盒说明书立即开展后续实验操作。