Department of Medicine, University of California San Diego, La Jolla, California, USA.
Department of Neurological Surgery, University of Chicago, Chicago, Illinois, USA.
FASEB J. 2022 Dec;36(12):e22629. doi: 10.1096/fj.202200907RR.
β1 integrins are important in blood vessel formation and function, finely tuning the adhesion of endothelial cells to each other and to the extracellular matrix. The role of integrins in the vascular disease, cerebral cavernous malformation (CCM) has yet to be explored in vivo. Endothelial loss of the gene KRIT1 leads to brain microvascular defects, resulting in debilitating and often fatal consequences. We tested administration of a monoclonal antibody that enforces the active β1 integrin conformation, (clone 9EG7), on a murine neonatal CCM mouse model, Krit1 ;Pdgfb-iCreERT2 (Krit1 ), and on KRIT1-silenced human umbilical vein endothelial cells (HUVECs). In addition, endothelial deletion of the master regulator of integrin activation, Talin 1 (Tln1), in Krit1 mice was performed to assess the effect of completely blocking endothelial integrin activation on CCM. Treatment with 9EG7 reduced lesion burden in the Krit1 model and was accompanied by a strong reduction in the phosphorylation of the ROCK substrate, myosin light chain (pMLC), in both retina and brain endothelial cells. Treatment of KRIT1-silenced HUVECs with 9EG7 in vitro stabilized cell-cell junctions. Overnight treatment of HUVECs with 9EG7 resulted in significantly reduced total surface expression of β1 integrin, which was associated with reduced pMLC levels, supporting our in vivo findings. Genetic blockade of integrin activation by Tln1 enhanced bleeding and did not reduce CCM lesion burden in Krit1 mice. In sum, targeting β1 integrin with an activated-specific antibody reduces acute murine CCM lesion development, which we found to be associated with suppression of endothelial ROCK activity.
β1 整合素在血管形成和功能中起着重要作用，精细调节内皮细胞彼此以及与细胞外基质的黏附。整合素在血管疾病、脑海绵状血管畸形（CCM）中的作用尚未在体内进行探索。内皮细胞 KRIT1 基因的缺失导致脑微血管缺陷，导致衰弱甚至常常致命的后果。我们在 Krit1 ;Pdgfb-iCreERT2（Krit1）新生鼠 CCM 模型和 KRIT1 沉默的人脐静脉内皮细胞（HUVEC）上测试了一种单克隆抗体（克隆 9EG7）的给药，该抗体强制激活β1 整合素构象。此外，还在 Krit1 小鼠中进行了内皮细胞整联蛋白激活的主调控因子 Talin 1（Tln1）的缺失，以评估完全阻断内皮整联蛋白激活对 CCM 的影响。9EG7 治疗可降低 Krit1 模型中的病变负担，并伴有视网膜和脑内皮细胞中 ROCK 底物肌球蛋白轻链（pMLC）的磷酸化强烈减少。9EG7 在体外处理 KRIT1 沉默的 HUVECs 可稳定细胞-细胞连接。HUVECs overnight 用 9EG7 处理可导致β1 整联蛋白总表面表达显著减少，这与 pMLC 水平降低相关，支持我们的体内发现。Tln1 对整合素激活的遗传阻断增强了出血，并且没有减少 Krit1 小鼠中的 CCM 病变负担。总之，用激活特异性抗体靶向β1 整合素可减少急性小鼠 CCM 病变的发展，我们发现这与抑制内皮 ROCK 活性有关。
