Human brain arteriovenous malformations express lymphatic‐associated genes

Abstract

ObjectiveBrain arteriovenous malformations (AVMs) are devastating, hemorrhage-prone, cerebrovascular lesions characterized by well-defined feeding arteries, draining vein(s) and the absence of a capillary bed. The endothelial cells (ECs) that comprise AVMs exhibit a loss of arterial and venous specification. Given the role of the transcription factor COUP-TFII in vascular development, EC specification, and pathological angiogenesis, we examined human AVM tissue to determine if COUP-FTII may have a role in AVM disease biology.MethodsWe examined 40 human brain AVMs by immunohistochemistry (IHC) and qRT-PCR for the expression of COUP-TFII as well as other genes involved in venous and lymphatic development, maintenance, and signaling. We also examined proliferation and EC tube formation with human umbilical ECs (HUVEC) following COUP-TFII overexpression.ResultsWe report that AVMs expressed COUP-TFII, SOX18, PROX1, NFATC1, FOXC2, TBX1, LYVE1, Podoplanin, and vascular endothelial growth factor (VEGF)-C, contained Ki67-positive cells and heterogeneously expressed genes involved in Hedgehog, Notch, Wnt, and VEGF signaling pathways. Overexpression of COUP-TFII alone in vitro resulted in increased EC proliferation and dilated tubes in an EC tube formation assay in HUVEC.InterpretationThis suggests AVM ECs are further losing their arterial/venous specificity and acquiring a partial lymphatic molecular phenotype. There was significant correlation of gene expression with presence of clinical edema and acute hemorrhage. While the precise role of these genes in the formation, stabilization, growth and risk of hemorrhage of AVMs remains unclear, these findings have potentially important implications for patient management and treatment choice, and opens new avenues for future work on AVM disease mechanisms.

Notch signaling pathway is a potential therapeutic target for extracranial vascular malformations

“…Patients with Alagille syndrome, a pleiotropic developmental disorder involving multiple organs, have demonstrated mutations in the Notch ligand Jag1 32 . Our results support and extend several studies which have identified NOTCH1, 3 and 4 overexpression in AVMs of the central nervous system (CNS) in humans 10,21,33 . Possible tissue-, species-, and developmental stage-specific differences in the role of Notch signaling underline the need to study both inhibition and up-regulation in human vascular malformations.…”

Notch signaling pathway is a potential therapeutic target for extracranial vascular malformations

“…Patients with Alagille syndrome, a pleiotropic developmental disorder involving multiple organs, have demonstrated mutations in the Notch ligand Jag1 32 . Our results support and extend several studies which have identified NOTCH1, 3 and 4 overexpression in AVMs of the central nervous system (CNS) in humans 10,21,33 . Possible tissue-, species-, and developmental stage-specific differences in the role of Notch signaling underline the need to study both inhibition and up-regulation in human vascular malformations.…”

Sonic hedgehog is expressed in human brain arteriovenous malformations and induces arteriovenous malformations in vivo

“…This is consistent with the recent demonstration that ECs of human brain AVMs co-express both arterial and venous markers, as they consist of not terminally differentiated vessels. 2 While the presence of COUP-TFII in human brain AVMs has been shown previously, 2,27 ours is the first demonstration that Shh and Gli1 are aberrantly expressed in the endothelial layer of human brain AVMs. Indeed, there is only one report that has analyzed the expression levels of various components of the Hh pathways in brain AVMs, finding heterogeneous expression of various Hh ligands and the Hh receptor Patched-1 across the AVMs that were analyzed, without conclusive results.…”

Germline Mutation Enrichment in Pathways Controlling Endothelial Cell Homeostasis in Patients with Brain Arteriovenous Malformation: Implication for Molecular Diagnosis

“…MAP2K3 is also involved [ 23 ] in the same pathway and, in particular, a physical interaction between TAK1 and MAP2K3 has been reported [ 24 ]. Involvement of inflammatory response in bAVM is, to date, well accepted [ 25 , 26 ] and in this context, we detected a nonsense mutation, the c.699G>A (p.Trp233Ter) in GIMAP1 gene. Together with the TGFβR2 signaling, Notch transduction pathways were also reported as promoting AVM development [ 27 ].…”

Notch signaling pathway is a potential therapeutic target for extracranial vascular malformations

“…Patients with Alagille syndrome, a pleiotropic developmental disorder involving multiple organs, have demonstrated mutations in the Notch ligand Jag1 32 . Our results support and extend several studies which have identified NOTCH1, 3 and 4 overexpression in AVMs of the central nervous system (CNS) in humans 10,21,33 . Possible tissue-, species-, and developmental stage-specific differences in the role of Notch signaling underline the need to study both inhibition and up-regulation in human vascular malformations.…”

Sonic hedgehog is expressed in human brain arteriovenous malformations and induces arteriovenous malformations in vivo

“…This is consistent with the recent demonstration that ECs of human brain AVMs co-express both arterial and venous markers, as they consist of not terminally differentiated vessels. 2 While the presence of COUP-TFII in human brain AVMs has been shown previously, 2,27 ours is the first demonstration that Shh and Gli1 are aberrantly expressed in the endothelial layer of human brain AVMs. Indeed, there is only one report that has analyzed the expression levels of various components of the Hh pathways in brain AVMs, finding heterogeneous expression of various Hh ligands and the Hh receptor Patched-1 across the AVMs that were analyzed, without conclusive results.…”

Germline Mutation Enrichment in Pathways Controlling Endothelial Cell Homeostasis in Patients with Brain Arteriovenous Malformation: Implication for Molecular Diagnosis

“…MAP2K3 is also involved [ 23 ] in the same pathway and, in particular, a physical interaction between TAK1 and MAP2K3 has been reported [ 24 ]. Involvement of inflammatory response in bAVM is, to date, well accepted [ 25 , 26 ] and in this context, we detected a nonsense mutation, the c.699G>A (p.Trp233Ter) in GIMAP1 gene. Together with the TGFβR2 signaling, Notch transduction pathways were also reported as promoting AVM development [ 27 ].…”

Notch signaling pathway is a potential therapeutic target for extracranial vascular malformations

“…Patients with Alagille syndrome, a pleiotropic developmental disorder involving multiple organs, have demonstrated mutations in the Notch ligand Jag1 32 . Our results support and extend several studies which have identified NOTCH1, 3 and 4 overexpression in AVMs of the central nervous system (CNS) in humans 10,21,33 . Possible tissue-, species-, and developmental stage-specific differences in the role of Notch signaling underline the need to study both inhibition and up-regulation in human vascular malformations.…”

Sonic hedgehog is expressed in human brain arteriovenous malformations and induces arteriovenous malformations in vivo

“…This is consistent with the recent demonstration that ECs of human brain AVMs co-express both arterial and venous markers, as they consist of not terminally differentiated vessels. 2 While the presence of COUP-TFII in human brain AVMs has been shown previously, 2,27 ours is the first demonstration that Shh and Gli1 are aberrantly expressed in the endothelial layer of human brain AVMs. Indeed, there is only one report that has analyzed the expression levels of various components of the Hh pathways in brain AVMs, finding heterogeneous expression of various Hh ligands and the Hh receptor Patched-1 across the AVMs that were analyzed, without conclusive results.…”

Germline Mutation Enrichment in Pathways Controlling Endothelial Cell Homeostasis in Patients with Brain Arteriovenous Malformation: Implication for Molecular Diagnosis

“…MAP2K3 is also involved [ 23 ] in the same pathway and, in particular, a physical interaction between TAK1 and MAP2K3 has been reported [ 24 ]. Involvement of inflammatory response in bAVM is, to date, well accepted [ 25 , 26 ] and in this context, we detected a nonsense mutation, the c.699G>A (p.Trp233Ter) in GIMAP1 gene. Together with the TGFβR2 signaling, Notch transduction pathways were also reported as promoting AVM development [ 27 ].…”