Induction of local angiotensin II-producing systems in stenotic aortic valves.
OBJECTIVE
The purpose of this study was to investigate the expression of angiotensin II (Ang II)-producing enzyme systems in normal and stenotic aortic valves.


BACKGROUND
Chronic inflammation and fibrosis are involved in the pathogenesis of aortic stenosis (AS), but the detailed molecular mechanisms of this atherosclerosis-like process remain obscure. Angiotensin II, a powerful mediator of inflammation and fibrosis, may participate in AS progression.


METHODS
Stenotic aortic valves (n = 86) were obtained from patients undergoing valve replacement surgery, and control valves (n = 11) were obtained from patients undergoing cardiac transplantation. Angiotensin-converting enzyme (ACE) and mast cell (MC)-derived chymase were quantified by reverse-transcription polymerase chain reaction, autoradiography, and immunostaining. The MCs, macrophages, and T lymphocytes were detected by immunohistochemistry, and angiotensin II type 1 receptor (AT-1R) by autoradiography.


RESULTS
Compared with control valves, stenotic aortic valves showed a significant increase in both messenger ribonucleic acid (mRNA) (p = 0.001) and protein (p < 0.001) expression of ACE, which colocalized with macrophages. Similarly, the expression of AT-1R protein and chymase mRNA and protein was upregulated (p < 0.001), and the number of MCs was six-fold higher in stenotic than in normal valves. The MCs were associated with the calcified areas, and-in contrast to control valves-showed an increased degree of degranulation, a prerequisite for chymase secretion and action.


CONCLUSIONS
Angiotensin-converting enzyme and chymase, two Ang II-forming enzymes, are locally expressed in aortic valves, and owing to infiltration of macrophages and MCs, are further upregulated in stenotic valves. These novel findings, implicating chronic inflammation and an increased expression of local Ang II-forming systems, suggest that therapeutic interventions aiming at inhibiting these processes may slow AS progression.
Helske
Satu
S
Wihuri Research Institute, Helsinki, Finland.
Lindstedt
Ken A
KA
Laine
Mika
M
Mäyränpää
Mikko
M
Werkkala
Kalervo
K
Lommi
Jyri
J
Turto
Heikki
H
Kupari
Markku
M
Kovanen
Petri T
PT
D000328:Adult; D000368:Aged; D000369:Aged, 80 and over; D000804:Angiotensin II / Q000096:biosynthesis*; D000806:Angiotensin-Converting Enzyme Inhibitors / Q000627:therapeutic use; D001021:Aortic Valve / Q000000981:diagnostic imaging / Q000378:metabolism*; D001024:Aortic Valve Stenosis / Q000378:metabolism* / Q000628:therapy; D053818:Chymases; D019918:Heart Valve Prosthesis Implantation; D006801:Humans; D007150:Immunohistochemistry; D008264:Macrophages / Q000378:metabolism; D008875:Middle Aged; D007703:Peptidyl-Dipeptidase A / Q000378:metabolism; D012333:RNA, Messenger / Q000378:metabolism; D011859:Radiography; D044140:Receptor, Angiotensin, Type 1 / Q000378:metabolism; D044139:Receptor, Angiotensin, Type 2 / Q000378:metabolism; D020133:Reverse Transcriptase Polymerase Chain Reaction; D012261:Ribonucleoproteins / Q000378:metabolism; D012697:Serine Endopeptidases / Q000378:metabolism; D013223:Statistics as Topic; D013601:T-Lymphocytes / Q000378:metabolism; D016896:Treatment Outcome; D053802:Tryptases
D000806:Angiotensin-Converting Enzyme Inhibitors; D012333:RNA, Messenger; D044140:Receptor, Angiotensin, Type 1; D044139:Receptor, Angiotensin, Type 2; D012261:Ribonucleoproteins; C026452:messenger ribonucleoprotein; D000804:Angiotensin II; D007703:Peptidyl-Dipeptidase A; D012697:Serine Endopeptidases; D053818:Chymases; D053802:Tryptases