Department of Neurosurgery, Beijing Tiantan Hospital, Capital Medical University, Beijing, 100070, China.
China National Clinical Research Center for Neurological Diseases, Beijing, 100070, China.
J Biomed Sci. 2024 May 13;31(1):51. doi: 10.1186/s12929-024-01040-7.
The fusiform aneurysm is a nonsaccular dilatation affecting the entire vessel wall over a short distance. Although PDGFRB somatic variants have been identified in fusiform intracranial aneurysms, the molecular and cellular mechanisms driving fusiform intracranial aneurysms due to PDGFRB somatic variants remain poorly understood.
In this study, single-cell sequencing and immunofluorescence were employed to investigate the phenotypic changes in smooth muscle cells within fusiform intracranial aneurysms. Whole-exome sequencing revealed the presence of PDGFRB gene mutations in fusiform intracranial aneurysms. Subsequent immunoprecipitation experiments further explored the functional alterations of these mutated PDGFRB proteins. For the common c.1684 mutation site of PDGFRβ, we established mutant smooth muscle cell lines and zebrafish models. These models allowed us to simulate the effects of PDGFRB mutations. We explored the major downstream cellular pathways affected by PDGFRB mutations and evaluated the potential therapeutic effects of Ruxolitinib.
Single-cell sequencing of two fusiform intracranial aneurysms sample revealed downregulated smooth muscle cell markers and overexpression of inflammation-related markers in vascular smooth muscle cells, which was validated by immunofluorescence staining, indicating smooth muscle cell phenotype modulation is involved in fusiform aneurysm. Whole-exome sequencing was performed on seven intracranial aneurysms (six fusiform and one saccular) and PDGFRB somatic mutations were detected in four fusiform aneurysms. Laser microdissection and Sanger sequencing results indicated that the PDGFRB mutations were present in smooth muscle layer. For the c.1684 (chr5: 149505131) site mutation reported many times, further cell experiments showed that PDGFRB mutations promoted inflammatory-related vascular smooth muscle cell phenotype and JAK-STAT pathway played a crucial role in the process. Notably, transfection of PDGFRB in zebrafish embryos resulted in cerebral vascular anomalies. Ruxolitinib, the JAK inhibitor, could reversed the smooth muscle cells phenotype modulation in vitro and inhibit the vascular anomalies in zebrafish induced by PDGFRB mutation.
Our findings suggested that PDGFRB somatic variants played a role in regulating smooth muscle cells phenotype modulation in fusiform aneurysms and offered a potential therapeutic option for fusiform aneurysms.
梭形动脉瘤是一种非囊状扩张，影响短距离内的整个血管壁。虽然 PDGFRB 体细胞变异已在梭形颅内动脉瘤中被发现，但导致 PDGFRB 体细胞变异的梭形颅内动脉瘤的分子和细胞机制仍知之甚少。
在这项研究中，采用单细胞测序和免疫荧光技术研究了梭形颅内动脉瘤中平滑肌细胞的表型变化。全外显子组测序显示梭形颅内动脉瘤中存在 PDGFRB 基因突变。随后的免疫沉淀实验进一步探讨了这些突变 PDGFRB 蛋白的功能改变。对于 PDGFRβ 的常见 c.1684 突变位点，我们建立了突变平滑肌细胞系和斑马鱼模型。这些模型允许我们模拟 PDGFRB 突变的影响。我们探讨了 PDGFRB 突变影响的主要下游细胞途径，并评估了 Ruxolitinib 的潜在治疗效果。
对两个梭形颅内动脉瘤样本进行单细胞测序，发现血管平滑肌细胞中平滑肌细胞标志物下调和炎症相关标志物过表达，免疫荧光染色验证了这一点，表明平滑肌细胞表型调节参与了梭形动脉瘤的形成。对 7 个颅内动脉瘤（6 个梭形和 1 个囊状）进行全外显子组测序，在 4 个梭形动脉瘤中检测到 PDGFRB 体细胞突变。激光显微切割和 Sanger 测序结果表明，PDGFRB 突变存在于平滑肌层中。对于多次报道的 c.1684(chr5:149505131) 位点突变，进一步的细胞实验表明，PDGFRB 突变促进了炎症相关的血管平滑肌细胞表型，JAK-STAT 途径在该过程中发挥了关键作用。值得注意的是，PDGFRB 转染斑马鱼胚胎导致脑血管异常。JAK 抑制剂 Ruxolitinib 可在体外逆转 PDGFRB 突变诱导的平滑肌细胞表型改变，并抑制斑马鱼血管异常。
我们的研究结果表明，PDGFRB 体细胞变异在调节梭形动脉瘤中平滑肌细胞表型改变中发挥作用，并为梭形动脉瘤提供了一种潜在的治疗选择。
