Dalal Alex R, Pedroza Albert J, Kim Jennifer L, Gilles Casey, Gu Wenduo, Kusadokoro Sho, Shad Rohan, Mitchel Olivia, Jackson William, Hiesinger William, Berry Gerald J, MacFarlane Elena G, Quertermous Thomas, Cheng Paul, Fischbein Michael P
Department of Cardiothoracic Surgery (A.R.D., A.J.P., J.L.K., C.G., S.K., R.S., O.M., W.H., M.P.F.), Stanford University School of Medicine, CA.
Division of Cardiovascular Medicine (W.G., W.J., T.Q., P.C.), Stanford University School of Medicine, CA.
Arterioscler Thromb Vasc Biol. 2025 May;45(5):722-742. doi: 10.1161/ATVBAHA.124.322069. Epub 2025 Mar 20.
Loeys-Dietz syndrome (LDS), caused by mutations in the TGF-β (transforming growth factor-β) signaling cascade, leads to aggressive thoracic aneurysms. While vascular smooth muscle cell (SMC) phenotype modulation has been implicated in thoracic aneurysm formation, we sought to characterize the role of cell state transitions in LDS aneurysm pathogenesis.
We performed single-cell transcriptomic characterization of aortic root/ascending aorta from a murine LDS model ( versus littermate WT [wild-type] control) at 8 weeks, 24 weeks, and aortic root/ascending aortic samples from human LDS surgical specimens (n=5 LDS [] and n=2 donor control) to understand cell state transitions and transcriptomic alterations in LDS. Select cell markers were spatially localized with RNA in situ hybridization, immunofluorescence, and immunohistochemistry. Single-cell RNA sequencing of murine and human LDS samples (>30 000 cells) revealed unique SMC, fibroblast, and macrophage transcriptomic profiles in LDS.
Instead of SMC phenotypic modulation seen in Marfan syndrome, transcriptomic alterations observed in LDS are most prominent in the adventitial fibroblast in the mouse model. While a distinct modulated SMC cluster does not appear in , SMCs transcriptomically differ from WT counterparts. Adventitial fibroblasts were activated into a proinflammatory state associated with increased macrophage recruitment (, , , and ) and fibrotic response genes (, , and ), with a 6-fold increase in aortic wall macrophage content in compared with WT. Similar findings were also observed in human LDS aortic samples with increased proinflammatory adventitial fibroblast transcriptomic program in parallel with heightened macrophage recruitment.
Despite phenotypic similarities in aneurysm formation, the dominant cellular and molecular mechanism of Marfan syndrome and LDS aneurysms are distinct. LDS mouse and human adventitial fibroblasts transcriptomically modulate into a proinflammatory state. Adventitial fibroblasts, in addition to SMCs, are another important pathological cell population during LDS aneurysm formation to consider for targeted therapy to potentially impede LDS aneurysm formation.
由转化生长因子-β（TGF-β）信号级联突变引起的洛伊迪茨综合征（LDS）会导致侵袭性胸主动脉瘤。虽然血管平滑肌细胞（SMC）表型调节与胸主动脉瘤形成有关，但我们试图明确细胞状态转变在LDS动脉瘤发病机制中的作用。
我们对8周龄的小鼠LDS模型（与同窝野生型[WT]对照相比）的主动脉根部/升主动脉以及人类LDS手术标本（n = 5例LDS []和n = 2例供体对照）的主动脉根部/升主动脉样本进行了单细胞转录组学特征分析，以了解LDS中的细胞状态转变和转录组改变。通过RNA原位杂交、免疫荧光和免疫组织化学对选定的细胞标志物进行空间定位。对小鼠和人类LDS样本（>30000个细胞）进行的单细胞RNA测序揭示了LDS中独特的SMC、成纤维细胞和巨噬细胞转录组谱。
与马凡综合征中观察到的SMC表型调节不同，在小鼠模型中，LDS中观察到的转录组改变在外膜成纤维细胞中最为显著。虽然在 中未出现明显的调节性SMC簇，但SMC在转录组上与野生型对应物不同。外膜成纤维细胞被激活为促炎状态，这与巨噬细胞募集增加（ 、 、 和 ）以及纤维化反应基因（ 、 、 和 ）有关，与野生型相比， 中主动脉壁巨噬细胞含量增加了6倍。在人类LDS主动脉样本中也观察到了类似的发现，促炎外膜成纤维细胞转录组程序增加，同时巨噬细胞募集增强。
尽管在动脉瘤形成方面存在表型相似性，但马凡综合征和LDS动脉瘤的主要细胞和分子机制是不同的。LDS小鼠和人类外膜成纤维细胞在转录组上调节为促炎状态。外膜成纤维细胞以及SMC是LDS动脉瘤形成过程中另一个重要的病理细胞群体，在考虑靶向治疗以潜在阻碍LDS动脉瘤形成时应予以关注。
