Different patterns of extracellular matrix protein expression in the convexity and the concavity of the dilated aorta with bicuspid aortic valve: preliminary results.
OBJECTIVE
This study aimed to assess extracellular matrix protein expression patterns at the convexity (right anterolateral wall) and the concavity of the dilated ascending aorta in patients with bicuspid aortic valve disease.


METHODS
Aortic wall specimens were retrieved from the convexity and the concavity in 27 bicuspid aortic valve patients (12 with stenosis and 15 with regurgitation) and 6 heart donors (controls). Morphometry, immunohistochemistry, Western blot, and polymerase chain reaction were performed, focusing on matrix proteins involved in vascular remodeling.


RESULTS
Type I and III collagens were significantly decreased in bicuspid-associated dilated aortas versus controls (P < .001), particularly at the convexity (P < .05 vs concavity). Expression of messenger RNA for collagens was lower than normal only in the regurgitant subgroup. At immunohistochemistry, proteins whose overproduction has been demonstrated in response to abnormal wall stress, such as tenascin and fibronectin, were more expressed in the convexity than in the concavity, especially in the stenosis subgroup. Tenascin, which is produced by smooth muscle cells in the synthetic phenotype, was nearly undetectable in controls. Fewer smooth muscle cells (stenosis, P = .017; regurgitation, P = .008) and more severe elastic fiber fragmentation (P = .029 and P < .001) were observed in the convexity versus the concavity.


CONCLUSIONS
In bicuspid-associated aortic dilations, an asymmetric pattern of matrix protein expression was found that was consistent with the asymmetry in wall-stress distribution reported previously. Differences exist between patients with stenosis and those with regurgitation in terms of protein expression and content in the aortic wall. Further studies could clarify the relations between these findings and the pathogenesis of aortic dilatation in bicuspid aortic valve patients.
Cotrufo
Maurizio
M
Department of Cardiothoracic and Respiratory Sciences, Second University of Naples, Italy.
Della Corte
Alessandro
A
De Santo
Luca S
LS
Quarto
Cesare
C
De Feo
Marisa
M
Romano
Gianpaolo
G
Amarelli
Cristiano
C
Scardone
Michelangelo
M
Di Meglio
Franca
F
Guerra
Germano
G
Scarano
Maria
M
Vitale
Serena
S
Castaldo
Clotilde
C
Montagnani
Stefania
S
D000368:Aged; D001011:Aorta / Q000378:metabolism / Q000473:pathology; D001018:Aortic Diseases / Q000378:metabolism*; D001021:Aortic Valve / Q000473:pathology; D001022:Aortic Valve Insufficiency / Q000151:congenital / Q000378:metabolism*; D001024:Aortic Valve Stenosis / Q000151:congenital / Q000378:metabolism*; D024042:Collagen Type I / Q000096:biosynthesis; D024061:Collagen Type III / Q000096:biosynthesis; D004108:Dilatation, Pathologic; D016326:Extracellular Matrix Proteins / Q000096:biosynthesis*; D006801:Humans; D008875:Middle Aged
D024042:Collagen Type I; D024061:Collagen Type III; D016326:Extracellular Matrix Proteins