Differential immediate-early gene responses to elevated pressure in porcine aortic valve interstitial cells.
OBJECTIVE
Cardiovascular risk factors are believed to play a role in the pathogenesis of aortic valve disease. In the present study the hypothesis was proposed that elevated pressure would cause a change in the expression of prototypical pro-inflammatory genes. Hence, the expression of MCP-1, osteopontin (OPN), VCAM-1, GM-CSF and PAI-1 was examined using semi-quantitative real-time RT-PCR.


METHODS
Porcine aortic valve interstitial cells at passage 1 were exposed to constant pressures of 100, 140, or 170 mmHg or cyclic pressures of 80-120, 120-160, or 150-190 mmHg for 2 h. Static cultures at atmospheric pressure served as controls. Total RNA from pooled experiments was isolated for analysis of gene expression. Single tube primer-mediated RT-PCR was performed directly on the RNA.


RESULTS
Cells responded differently to constant and cyclic pressure. The most notable response was the expression of OPN, which was significantly up-regulated under steady conditions but down-regulated under cyclic conditions. The opposite was true in VCAM-1 expression, which was significantly down-regulated at 170 mmHg static pressure, but up-regulated at 140 and 170 mmHg mean cyclic pressure. There was no clear proportional correlation between pressure magnitude and expression of MCP-1, GM-CSF, or PAI-1. However, elevated cyclic pressure caused a proportional increase in VCAM-1 expression and a proportional decrease in OPN expression.


CONCLUSIONS
Elevated cyclic pressure is a potent stimulus for the up-regulation of VCAM-1 expression and the down-regulation of OPN expression. This demonstrates an association between hypertension and aortic valve stenosis and calcification. The regulation of the chemotactic genes MCP-1 and GM-CSF is not correlated to a change in compressive forces.
Warnock
James N
JN
Agricultural and Biological Engineering, Mississippi State University, Box 9632, Mississippi State, MS 39762-9632, USA. jwarnock@abe.msstate.edu
Burgess
Shane C
SC
Shack
Allen
A
Yoganathan
Ajit P
AP
D000818:Animals; D001021:Aortic Valve / Q000166:cytology / Q000378:metabolism*; D001024:Aortic Valve Stenosis / Q000378:metabolism; D001794:Blood Pressure; D018932:Chemokine CCL2 / Q000378:metabolism; D003199:Computer Systems; D004195:Disease Models, Animal; D015536:Down-Regulation; D005786:Gene Expression Regulation; D017781:Genes, Immediate-Early; D016178:Granulocyte-Macrophage Colony-Stimulating Factor / Q000378:metabolism; D006973:Hypertension / Q000378:metabolism; D053495:Osteopontin; D017395:Plasminogen Activator Inhibitor 1 / Q000378:metabolism; D012333:RNA, Messenger / Q000378:metabolism; D020133:Reverse Transcriptase Polymerase Chain Reaction; D012795:Sialoglycoproteins / Q000378:metabolism; D013552:Swine; D015854:Up-Regulation; D019010:Vascular Cell Adhesion Molecule-1 / Q000378:metabolism
D018932:Chemokine CCL2; D017395:Plasminogen Activator Inhibitor 1; D012333:RNA, Messenger; D012795:Sialoglycoproteins; D019010:Vascular Cell Adhesion Molecule-1; D053495:Osteopontin; D016178:Granulocyte-Macrophage Colony-Stimulating Factor