Decreased plasminogen activator inhibitor and tissue metalloproteinase inhibitor expression may promote increased metalloproteinase activity with increasing duration of human atrial fibrillation.
BACKGROUND
Atrial fibrosis has been shown to concur with the persistence of atrial fibrillation (AF) and is only incompletely reversible, thus counteracting attempts to restore and maintain sinus rhythm (SR). Besides the angiotensin system, the matrix metalloproteinases (MMP) play a major role in the pathogenesis of fibrosis. Thus, the present study investigated changes of the MMP system during the development of human AF.


RESULTS
Right atrial appendages of 146 patients were excised during heart surgery and grouped according to rhythm (SR vs AF) and AF duration. Hydroxyproline as a surrogate for collagen content and morphometrically determined collagen content increased significantly from SR (14.3 +/- 7.7%) to chronic permanent AF (CAF) of 6-24 months (21.2 +/- 9.2%, P = 0.02), and CAF of > 60 months (25.3 +/- 4.7%, P < 0.01). From SR to paroxysmal and chronic persistent AF (CPAF) and to CAF MMP-2 and MMP-9 activity rose, while their mRNA and protein levels were not altered significantly. Plasminogen activator inhibitor (PAI), an inhibitor of a potent activator of many MMPs, was significantly decreased with increasing duration of AF. In parallel, the mRNA levels of the tissue inhibitors of MMPs TIMP-1 and -2 decreased significantly.


CONCLUSIONS
Human atrial fibrogenesis is enhanced with increasing duration of AF: a longer AF duration is associated with elevated atrial interstitial MMP activity, but decreased PAI and TIMP expression.
Gramley
Felix
F
Department of Cardiology, Technical University Aachen, Aachen, Germany.
Lorenzen
Johann
J
Plisiene
Jurgita
J
Rakauskas
Mindaugas
M
Benetis
Rimantas
R
Schmid
Michael
M
Autschbach
Rüdiger
R
Knackstedt
Christian
C
Schimpf
Thomas
T
Mischke
Karl
K
Gressner
Axel
A
Hanrath
Peter
P
Kelm
Malte
M
Schauerte
Patrick
P
D000368:Aged; D001281:Atrial Fibrillation / Q000378:metabolism* / Q000473:pathology; D004789:Enzyme Activation / Q000502:physiology; D005260:Female; D005786:Gene Expression Regulation / Q000502:physiology; D006801:Humans; D008297:Male; D020782:Matrix Metalloproteinases / Q000096:biosynthesis* / Q000235:genetics; D008875:Middle Aged; D015849:Plasminogen Inactivators / Q000096:biosynthesis* / Q000235:genetics / Q000502:physiology; D013997:Time Factors; D019714:Tissue Inhibitor of Metalloproteinases / Q000096:biosynthesis* / Q000235:genetics
D015849:Plasminogen Inactivators; D019714:Tissue Inhibitor of Metalloproteinases; D020782:Matrix Metalloproteinases