BACKGROUND:The precise origin of newly formed ACTA2+ (alpha smooth muscle actin-positive) cells appearing in nonmuscularized vessels in the context of pulmonary hypertension is still debatable although it is believed that they predominantly derive from preexisting vascular smooth muscle cells (VSMCs).METHODS:Gli1^Cre-ERT2; tdTomato^flox mice were used to lineage trace GLI1+ (glioma-associated oncogene homolog 1-positive) cells in the context of pulmonary hypertension using 2 independent models of vascular remodeling and reverse remodeling: hypoxia and cigarette smoke exposure. Hemodynamic measurements, right ventricular hypertrophy assessment, flow cytometry, and histological analysis of thick lung sections followed by state-of-the-art 3-dimensional reconstruction and quantification using Imaris software were used to investigate the contribution of GLI1+ cells to neomuscularization of the pulmonary vasculature.RESULTS:The data show that GLI1+ cells are abundant around distal, nonmuscularized vessels during steady state, and this lineage contributes to around 50% of newly formed ACTA2+ cells around these normally nonmuscularized vessels. During reverse remodeling, cells derived from the GLI1+ lineage are largely cleared in parallel to the reversal of muscularization. Partial ablation of GLI1+ cells greatly prevented vascular remodeling in response to hypoxia and attenuated the increase in right ventricular systolic pressure and right heart hypertrophy. Single-cell RNA sequencing on sorted lineage-labeled GLI1+ cells revealed an Acta2^high fraction of cells with pathways in cancer and MAPK signaling as potential players in reprogramming these cells during vascular remodeling. Analysis of human lung-derived material suggests that GLI1 signaling is overactivated in both group 1 and group 3 pulmonary hypertension and can promote proliferation and myogenic differentiation.CONCLUSIONS:Our data highlight GLI1+ cells as an alternative cellular source of VSMCs in pulmonary hypertension and suggest that these cells and the associated signaling pathways represent an important therapeutic target for further studies.

中文翻译：

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GLI1+ 细胞有助于肺动脉高压的血管重塑

背景：在肺动脉高压的情况下，出现在非肌肉化血管中的新形成的 ACTA2+（α 平滑肌肌动蛋白阳性）细胞的确切起源仍然存在争议，尽管人们相信它们主要源自先前存在的血管平滑肌细胞 (VSMC)。 : Gli1 ^Cre-ERT2 ; tdTomato ^flox小鼠被用来在肺动脉高压的情况下追踪 GLI1+（神经胶质瘤相关癌基因同源物 1 阳性）细胞的谱系，使用 2 个独立的血管重塑和逆重塑模型：缺氧和香烟烟雾暴露。使用血流动力学测量、右心室肥厚评估、流式细胞术和厚肺切片的组织学分析，然后使用 Imaris 软件进行最先进的 3 维重建和量化，以研究 GLI1+ 细胞对肺新肌肉化的贡献结果：数据显示，在稳定状态下，GLI1+ 细胞在远端非肌肉化血管周围大量存在，并且这种谱系促成了这些正常非肌肉化血管周围新形成的 ACTA2+ 细胞的 50% 左右。在逆重塑过程中，源自 GLI1+ 谱系的细胞在肌肉化逆转的同时大部分被清除。 GLI1+细胞的部分消融极大地阻止了缺氧引起的血管重塑，并减弱了右心室收缩压和右心肥厚的增加。对分选的谱系标记的 GLI1+ 细胞进行单细胞 RNA 测序显示，Acta2^高比例的细胞具有癌症通路和 MAPK 信号传导，是血管重塑过程中重新编程这些细胞的潜在参与者。对人肺源性材料的分析表明，GLI1 信号传导在第 1 组和第 3 组肺动脉高压中过度激活，并且可以促进增殖和肌源性分化。结论：我们的数据强调 GLI1+ 细胞是肺动脉高压中 VSMC 的替代细胞来源，并表明这些细胞和相关的信号通路代表了进一步研究的重要治疗靶点。