Increased metabolite levels of glycolysis and pentose phosphate pathway in rabbit atherosclerotic arteries and hypoxic macrophage.
OBJECTIVE
Inflammation and possibly hypoxia largely affect glucose utilization in atherosclerotic arteries, which could alter many metabolic systems. However, metabolic changes in atherosclerotic plaques remain unknown. The present study aims to identify changes in metabolic systems relative to glucose uptake and hypoxia in rabbit atherosclerotic arteries and cultured macrophages.


METHODS
Macrophage-rich or smooth muscle cell (SMC)-rich neointima was created by balloon injury in the iliac-femoral arteries of rabbits fed with a 0.5% cholesterol diet or a conventional diet. THP-1 macrophages stimulated with lipopolysaccharides (LPS) and interferon-γ (INFγ) were cultured under normoxic and hypoxic conditions. We evaluated comprehensive arterial and macrophage metabolism by performing metabolomic analyses using capillary electrophoresis-time of flight mass spectrometry. We evaluated glucose uptake and its relationship to vascular hypoxia using (18)F-fluorodeoxyglucose ((18)F-FDG) and pimonidazole, a marker of hypoxia.


RESULTS
The levels of many metabolites increased in the iliac-femoral arteries with macrophage-rich neointima, compared with those that were not injured and those with SMC-rich neointima (glycolysis, 4 of 9; pentose phosphate pathway, 4 of 6; tricarboxylic acid cycle, 4 of 6; nucleotides, 10 of 20). The uptake of (18)F-FDG in arterial walls measured by autoradiography positively correlated with macrophage- and pimonidazole-immunopositive areas (r = 0.76, and r = 0.59 respectively; n = 69 for both; p<0.0001). Pimonidazole immunoreactivity was closely localized with the nuclear translocation of hypoxia inducible factor-1α and hexokinase II expression in macrophage-rich neointima. The levels of glycolytic (8 of 8) and pentose phosphate pathway (4 of 6) metabolites increased in LPS and INFγ stimulated macrophages under hypoxic but not normoxic condition. Plasminogen activator inhibitor-1 protein levels in the supernatant were closely associated with metabolic pathways in the macrophages.


CONCLUSIONS
Infiltrative macrophages in atherosclerotic arteries might affect metabolic systems, and hypoxia but not classical activation might augment glycolytic and pentose phosphate pathways in macrophages.
Department of Pathology, University of Miyazaki, Miyazaki, Japan.
Atsushi
A
Yamashita
Department of Tracer Kinetics & Bioanalysis, Hokkaido University, Sapporo, Japan.
Yan
Y
Zhao
Department of Pathology, University of Miyazaki, Miyazaki, Japan ; Department of Internal Medicine, Faculty of Medicine, University of Miyazaki, Miyazaki, Japan.
Yunosuke
Y
Matsuura
Department of Tracer Kinetics & Bioanalysis, Hokkaido University, Sapporo, Japan.
Kazuaki
K
Yamasaki
Department of Pathology, University of Miyazaki, Miyazaki, Japan.
Sayaka
S
Moriguchi-Goto
Department of Pathology, University of Miyazaki, Miyazaki, Japan.
Chihiro
C
Sugita
Department of Pathology, University of Miyazaki, Miyazaki, Japan ; Department of Internal Medicine, Faculty of Medicine, University of Miyazaki, Miyazaki, Japan.
Takashi
T
Iwakiri
Department of Pathology, University of Miyazaki, Miyazaki, Japan.
Nozomi
N
Okuyama
Frontier Science Research Center, University of Miyazaki, Miyazaki, Japan.
Chihiro
C
Koshimoto
Faculty of Health Sciences, Institute of Medical, Pharmaceutical and Health Sciences, Kanazawa University, Ishikawa, Japan ; Biomedical Imaging Research Center, University of Fukui, Fukui, Japan.
Keiichi
K
Kawai
Department of Nuclear Medicine, Graduate School of Medicine, Hokkaido University, Sapporo, Japan.
Nagara
N
Tamaki
Department of Tracer Kinetics & Bioanalysis, Hokkaido University, Sapporo, Japan.
Songji
S
Zhao
Central Institute of Isotope Science, Hokkaido University, Sapporo, Japan.
Yuji
Y
Kuge
Department of Pathology, University of Miyazaki, Miyazaki, Japan.
Yujiro
Y
Asada
D021581:Active Transport, Cell Nucleus; D000818:Animals; D050197:Atherosclerosis / Q000000981:diagnostic imaging / Q000378:metabolism*; D015687:Cell Hypoxia; D002460:Cell Line; D005263:Femoral Artery / Q000000981:diagnostic imaging / Q000378:metabolism* / Q000473:pathology; D019788:Fluorodeoxyglucose F18 / Q000493:pharmacokinetics; D006019:Glycolysis; D006801:Humans; D051795:Hypoxia-Inducible Factor 1, alpha Subunit / Q000378:metabolism; D008264:Macrophages / Q000378:metabolism*; D008297:Male; D055442:Metabolome; D010427:Pentose Phosphate Pathway; D011817:Rabbits; D011877:Radionuclide Imaging; D019275:Radiopharmaceuticals / Q000493:pharmacokinetics; D013925:Thromboplastin / Q000378:metabolism; D014018:Tissue Distribution
D051795:Hypoxia-Inducible Factor 1, alpha Subunit; D019275:Radiopharmaceuticals; D019788:Fluorodeoxyglucose F18; D013925:Thromboplastin