Inflammatory infiltrates and neovessels are relevant sources of MMPs in abdominal aortic aneurysm wall.
OBJECTIVE
Abdominal aortic aneurysm (AAA) wall is characterized by degradation of extracellular matrix through matrix metalloproteinases (MMPs), chronic inflammatory cell infiltration and extensive neovascularization. So far, MMP expression within AAA wall in association with infiltrates and neovascularization has not yet been studied.


METHODS
Vessel walls of 15 AAA patients and 8 organ donors were analyzed by immunohistochemistry for expression of various MMPs (MMP-1, -2, -3, -7, -8, -9, -12 and -13) in all cells located within the AAAs and correlated with infiltrates and neovascularization.


RESULTS
Luminal endothelial cells (ECs) were positive for MMP-1, -3 and -9, ECs of mature neovessels were furthermore positive for MMP-2. Immature neovessels expressed all MMPs tested except for MMP-13. Aortic medial smooth muscle cells (SMCs) expressed MMP-1, -2, -3 and -9, SMCs of mature neovessels, only MMP-1, -3 and -9. Inflammatory infiltrates expressed all MMPs tested except for MMP-2, macrophages expressed all MMPs. Infiltrates were composed mainly of B cells (58.5 +/- 10.9%) and T lymphocytes (26.3 +/- 9.5%). Furthermore, significant inverse correlations were found between the amounts of inflammatory cells, neovessels and collagen/elastin content of the aortic vessel wall (r = +0.806/p < 0.001, r = -0.650/p = 0.012, r = -0.63/p < 0.015; respectively).


CONCLUSIONS
Inflammatory infiltrates and invading neovessels are relevant sources of MMPs in the AAA wall and may substantially contribute to aneurysm wall instability.
Reeps
Christian
C
Department of Vascular Surgery, Klinikum rechts der Isar der Technischen Universitat Munchen, Munich, Germany.
Pelisek
Jaroslav
J
Seidl
Stefan
S
Schuster
Tibor
T
Zimmermann
Alexander
A
Kuehnl
Andreas
A
Eckstein
Hans-Henning
HH
D000368:Aged; D000369:Aged, 80 and over; D017544:Aortic Aneurysm, Abdominal / Q000201:enzymology* / Q000276:immunology / Q000473:pathology; D003094:Collagen / Q000378:metabolism; D004549:Elastin / Q000378:metabolism; D042783:Endothelial Cells / Q000201:enzymology; D005260:Female; D006801:Humans; D007150:Immunohistochemistry; D007249:Inflammation / Q000201:enzymology* / Q000276:immunology / Q000473:pathology; D008297:Male; D020782:Matrix Metalloproteinases / Q000096:biosynthesis*; D008875:Middle Aged; D032389:Myocytes, Smooth Muscle / Q000201:enzymology; D009389:Neovascularization, Pathologic / Q000201:enzymology* / Q000378:metabolism / Q000473:pathology
D003094:Collagen; D004549:Elastin; D020782:Matrix Metalloproteinases