Role of endothelial PDGFB in arterio-venous malformations pathogenesis

Inhibition of Angiopoietin-2 rescues sporadic brain arteriovenous malformations by reducing pericyte loss

Brain arteriovenous malformations (bAVMs) are a major cause of hemorrhagic stroke in children and young adults. These lesions are thought to result from somatic KRAS/BRAF mutations in brain endothelial cells (bECs). In this study, we introduce a new bAVM model by inducing a brain endothelial-specific BrafV600E mutation using the Slc1o1c1(BAC)-CreER driver line. The pathological characteristics of this model resemble human bAVMs, including dilated and hyperpermeable vessels, as well as parenchymal hemorrhage. We observed that these lesions showed a typical reduction in pericyte coverage and disruption of the pericyte-endothelial cell connection. Additionally, we found that ANGPT2 levels were significantly increased in the endothelium of bAVM lesions, which may be a critical factor in the pericyte deficits of the malformed vessels. Treatment with an ANGPT2 neutralizing antibody confirmed that blocking ANGPT2 can restore pericyte density in bAVM lesions, improve pericyte coverage around microvessels, enhance tight junction protein coverage related to endothelial cells, and normalize endothelial barrier function. In summary, our findings suggest that increased ANGPT2 expression in endothelial cells with the BrafV600E mutation is a key factor in pericyte deficiencies in bAVMs, highlighting the potential effectiveness of anti-ANGPT2 therapy in treating bAVMs.

Cerebral vascular malformations: pathogenesis and therapy

Cerebral vascular malformations (CVMs), particularly cerebral cavernous malformations and cerebral arteriovenous malformations, pose significant neurological challenges due to their complex etiologies and clinical implications. Traditionally viewed as congenital conditions with structural abnormalities, CVMs have been treated primarily through resection, embolization, and stereotactic radiosurgery. While these approaches offer some efficacy, they often pose risks to neurological integrity due to their invasive nature. Advances in next-generation sequencing, particularly high-depth whole-exome sequencing and bioinformatics, have facilitated the identification of gene variants from neurosurgically resected CVMs samples. These advancements have deepened our understanding of CVM pathogenesis. Somatic mutations in key mechanistic pathways have been identified as causative factors, leading to a paradigm shift in CVM treatment. Additionally, recent progress in noninvasive and minimally invasive techniques, including gene imaging genomics, liquid biopsy, or endovascular biopsies (endovascular sampling of blood vessel lumens), has enabled the identification of gene variants associated with CVMs. These methods, in conjunction with clinical data, offer potential for early detection, dynamic monitoring, and targeted therapies that could be used as monotherapy or adjuncts to surgery. This review highlights advancements in CVM pathogenesis and precision therapies, outlining the future potential of precision medicine in CVM management.