Bialkowska Katarzyna, Szpak Dorota, Verbovetskiy Dmitriy, Qin Jun, Cherepanova Olga A, Plow Edward F, Pluskota Elzbieta
Department of Cardiovascular and Metabolic Sciences, Lerner Research Institute, Cleveland Clinic, Cleveland, Ohio, USA.
FASEB J. 2025 Jul 31;39(14):e70823. doi: 10.1096/fj.202402977R.
Crucial to homeostasis, vascular barrier function depends upon coordinated interplay between endothelial (ECs) and mural cells, including vascular smooth muscle cells (vSMCs) and pericytes, that stabilize the vasculature. Kindlin-2 (K2) is an integrin co-activator regulating various cellular responses, but its role in mural cell-dependent vascular stabilization is unknown. The role of K2 in mural cell-mediated regulation of vascular barrier function was investigated. Vascular permeability was assessed in SMC/pericyte-specific tamoxifen-inducible K2 knockout (Fermt2 Myh11-CreERT2 ROSA26-floxed STOP eYFP), lineage tracing mice (K2) and their K2 wild-type littermates (K2). In Miles assays, K2 mice showed increased basal by (20%-75%) and vEGF, PAF, or mustard oil-induced vascular permeability of Evans blue into the skin (by 2- to 3-fold) compared to K2 mice. In LPS-induced sepsis, vascular leakage into the lungs and liver was 50% higher in K2 mice than in K2 littermates. The enhanced vascular leakiness in K2 mice was due to aberrant vasculature characterized by decreased coverage with vSMCs. In ex vivo experiments, K2 aortic vSMCs and brain pericytes had severely reduced β1 and β3 integrin activation, leading to attenuated adhesion to integrin ligands (by ~60%-80%) compared to the K2 cells. K2 vSMCs showed diminished interactions with ECs during endothelial tube formation, dedifferentiation, and enhanced apoptosis. The same effect was observed in human aortic vSMCs upon 50% K2 downregulation with K2-specific shRNA. In contrast to K2, the K2 pericytes failed to support barrier formation by brain microvascular ECs in the ex vivo blood-brain barrier model. Together, K2 as an integrin coactivator sustains mural cell functions, contributing to vascular stabilization.
血管屏障功能对于体内平衡至关重要，它依赖于内皮细胞（ECs）与壁细胞（包括血管平滑肌细胞（vSMCs）和周细胞）之间的协调相互作用，这些细胞可稳定脉管系统。Kindlin-2（K2）是一种整合素共激活因子，可调节各种细胞反应，但其在壁细胞依赖性血管稳定中的作用尚不清楚。本研究调查了K2在壁细胞介导的血管屏障功能调节中的作用。在平滑肌细胞/周细胞特异性他莫昔芬诱导的K2基因敲除小鼠（Fermt2 Myh11-CreERT2 ROSA26- floxed STOP eYFP）、谱系追踪小鼠（K2）及其K2野生型同窝小鼠（K2）中评估血管通透性。在迈尔斯试验中，与K2小鼠相比，K2小鼠的基础血管通透性增加了（20%-75%），并且血管内皮生长因子（VEGF）、血小板活化因子（PAF）或芥子油诱导的伊文思蓝进入皮肤的血管通透性增加了（2至3倍）。在脂多糖（LPS）诱导的脓毒症中，K2小鼠肺部和肝脏的血管渗漏比K2同窝小鼠高50%。K2小鼠血管渗漏增强是由于血管异常，其特征是vSMCs覆盖减少。在体外实验中，与K2细胞相比，K2主动脉vSMCs和脑周细胞的β1和β3整合素激活严重降低，导致与整合素配体的粘附减弱（约60%-80%）。K2 vSMCs在内皮管形成、去分化过程中与ECs的相互作用减少，且细胞凋亡增加。用K2特异性短发夹RNA将人主动脉vSMCs中的K2下调50%后，也观察到了相同的效果。与K2相反，在体外血脑屏障模型中，K2周细胞未能支持脑微血管ECs形成屏障。总之，K2作为一种整合素共激活因子维持壁细胞功能，有助于血管稳定。
