Hypoxia, hypoxia-inducible transcription factor, and macrophages in human atherosclerotic plaques are correlated with intraplaque angiogenesis.
OBJECTIVE
We sought to examine the presence of hypoxia in human carotid atherosclerosis and its association with hypoxia-inducible transcription factor (HIF) and intraplaque angiogenesis.


BACKGROUND
Atherosclerotic plaques develop intraplaque angiogenesis, which is a typical feature of hypoxic tissue and expression of HIF.


METHODS
To examine the presence of hypoxia in atherosclerotic plaques, the hypoxia marker pimonidazole was infused before carotid endarterectomy in 7 symptomatic patients. Also, the messenger ribonucleic acid (mRNA) and protein expression of HIF1 alpha, HIF2 alpha, HIF-responsive genes (vascular endothelial growth factor [VEGF], glucose transporter [GLUT]1, GLUT3, hexokinase [HK]1, and HK2), and microvessel density were determined in a larger series of nondiseased and atherosclerotic carotid arteries with microarray, quantitative reverse transcription polymerase chain reaction, in situ hybridization, and immunohistochemistry.


RESULTS
Pimonidazole immunohistochemistry demonstrated the presence of hypoxia, especially within the macrophage-rich center of the lesions. Hypoxia correlated with the presence of a thrombus, angiogenesis, and expression of CD68, HIF, and VEGF. The mRNA and protein expression of HIF, its target genes, and microvessel density increased from early to stable lesions, but no changes were observed between stable and ruptured lesions.


CONCLUSIONS
This is the first study directly demonstrating hypoxia in advanced human atherosclerosis and its correlation with the presence of macrophages and the expression of HIF and VEGF. Also, the HIF pathway was associated with lesion progression and angiogenesis, suggesting its involvement in the response to hypoxia and the regulation of human intraplaque angiogenesis.
Sluimer
Judith C
JC
Department of Pathology, Cardiovascular Research Institute Maastricht (CARIM), University of Maastricht, Maastricht, The Netherlands.
Gasc
Jean-Marie
JM
van Wanroij
Job L
JL
Kisters
Natasja
N
Groeneweg
Mathijs
M
Sollewijn Gelpke
Maarten D
MD
Cleutjens
Jack P
JP
van den Akker
Luc H
LH
Corvol
Pierre
P
Wouters
Bradly G
BG
Daemen
Mat J
MJ
Bijnens
Ann-Pascale J
AP
D000368:Aged; D015703:Antigens, CD / Q000378:metabolism; D015214:Antigens, Differentiation, Myelomonocytic / Q000378:metabolism; D015415:Biomarkers; D016893:Carotid Stenosis / Q000503:physiopathology*; D003430:Cross-Sectional Studies; D018450:Disease Progression; D016894:Endarterectomy, Carotid; D005260:Female; D006801:Humans; D000860:Hypoxia / Q000503:physiopathology*; D051793:Hypoxia-Inducible Factor 1 / Q000378:metabolism*; D007150:Immunohistochemistry; D008264:Macrophages; D008297:Male; D008875:Middle Aged; D009389:Neovascularization, Pathologic; D009593:Nitroimidazoles; D018384:Oxidative Stress; D012333:RNA, Messenger; D042461:Vascular Endothelial Growth Factor A / Q000378:metabolism; D000097382:CD68 Molecule
D015703:Antigens, CD; D015214:Antigens, Differentiation, Myelomonocytic; D015415:Biomarkers; D051793:Hypoxia-Inducible Factor 1; D009593:Nitroimidazoles; D012333:RNA, Messenger; D042461:Vascular Endothelial Growth Factor A; C067980:CD68 antigen, human; D000097382:CD68 Molecule; C033815:pimonidazole