Impact of monocyte chemoattractant protein-1 deficiency on cerebral aneurysm formation.
OBJECTIVE
Recent studies have suggested that chronic inflammation actively participates in cerebral aneurysm (CA) formation. Macrophages accumulate in CA walls and express proinflammatory genes promoting CA progression, but the molecular mechanisms of monocyte/macrophage recruitment into CA walls remain to be elucidated.


METHODS
Monocyte chemoattractant protein-1 (MCP-1) expression in experimentally induced CAs was assessed by immunohistochemistry and Western blotting. The role of MCP-1 in CA formation was examined by MCP-1(-/-) mice and a plasmid DNA encoding a dominant negative mutant of MCP-1 (7ND). MCP-1 expression in human CAs was examined by immunohistochemistry.


RESULTS
MCP-1 expression was upregulated in aneurysmal walls at the early stage of CA formation. MCP-1(-/-) mice exhibited a significant decrease of CA formation and macrophage accumulation with decreased expression of matrix metalloproteinase-2, -9, and inducible nitric oxide synthase. Immunohistochemistry for the DNA binding form of nuclear factor-kappa B showed nuclear factor-kappa B activation in MCP-1-expressing cells. Blockade of MCP-1 activity by 7ND resulted in the inhibition of CA progression in rats. In human CAs, MCP-1 was also expressed in CA walls.


CONCLUSIONS
These data suggest that MCP-1 plays a crucial role in CA formation as a major chemoattractant for monocyte/macrophage. MCP-1 expression in CA walls is induced through nuclear factor-kappa B activation. MCP-1 may be a novel therapeutic target of medical treatment preventing CA progression.
Aoki
Tomohiro
T
Department of Neurosurgery, Kyoto University Graduate School of Medicine, Kyoto, Japan.
Kataoka
Hiroharu
H
Ishibashi
Ryota
R
Nozaki
Kazuhiko
K
Egashira
Kensuke
K
Hashimoto
Nobuo
N
D000818:Animals; D001158:Arteries / Q000473:pathology; D001794:Blood Pressure / Q000235:genetics / Q000502:physiology; D015153:Blotting, Western; D002452:Cell Count; D018932:Chemokine CCL2 / Q000172:deficiency*; D006801:Humans; D007150:Immunohistochemistry; D002532:Intracranial Aneurysm / Q000235:genetics* / Q000473:pathology*; D008264:Macrophages / Q000502:physiology; D020778:Matrix Metalloproteinase 2 / Q000378:metabolism; D020780:Matrix Metalloproteinase 9 / Q000378:metabolism; D051379:Mice; D008810:Mice, Inbred C57BL; D018345:Mice, Knockout; D009154:Mutation / Q000502:physiology; D016328:NF-kappa B / Q000235:genetics / Q000502:physiology; D051381:Rats; D051996:Transcription Factor RelA / Q000235:genetics / Q000378:metabolism
D018932:Chemokine CCL2; D016328:NF-kappa B; D051996:Transcription Factor RelA; D020778:Matrix Metalloproteinase 2; D020780:Matrix Metalloproteinase 9