Differential effects of Rho-kinase inhibition on artery wall mass and remodeling.
OBJECTIVE
Constrictive remodeling and new artery wall mass contribute to lumen narrowing in atherosclerosis and following injury. Rho-kinase, an important regulator of myosin phosphorylation and cytoskeletal reorganization, is critical to smooth muscle cell (SMC) growth and vasoconstriction, but its role in artery wall remodeling is poorly defined. We hypothesized that constrictive artery wall remodeling is dependent on Rho signaling so that blocking Rho-kinase would promote outward artery wall remodeling in response to intimal hyperplasia and thus limit lumen narrowing.


METHODS
To test this hypothesis, we first studied the effects of the Rho-kinase inhibitor fasudil on SMC remodeling of collagen matrix in vitro. Mouse aortic SMCs were seeded into three-dimensional collagen gels with and without fasudil, and extent of contraction was measured at 24 hours. We then used the mouse carotid ligation model to study the effects of Rho-kinase inhibition on remodeling and intimal hyperplasia in vivo. C57B6/J mice were randomly assigned to fasudil (100 mg/kg per day) or vehicle and underwent unilateral carotid artery ligation or sham ligation. Remodeling and wall mass were measured after 28 days.


RESULTS
Fasudil blocked SMC contraction of collagen gels in a dose-dependent manner. Complete inhibition of collagen gel remodeling was achieved between 10 and 30 micromol/L fasudil. In control mice, carotid ligation caused significant thickening of the adventitia, media, and intima (P <.01) and outward remodeling of the carotid wall. The external elastic lamina (EEL) area increased by 14% versus sham (P <.05), but this increase was insufficient to prevent lumen narrowing (-42% vs sham, P <.05). Fasudil treatment had favorable effects on wall mass, inhibiting neointimal (P =.04), medial (P =.03), and adventitial thickening (P =.07) versus controls. Opposite our hypothesis, however, fasudil did not enhance outward artery wall remodeling or improve lumen caliber. Rather, inhibiting Rho-kinase blocked outward remodeling in response to ligation. EEL area was significantly smaller in treated versus control animals (P =.04) and slightly smaller versus shams (P = NS). These data suggest that Rho activation contributes significantly to both hyperplasia and outward remodeling of the injured artery wall. Rho-kinase may prove an important target to limit intimal hyperplasia and prevent restenosis when remodeling is improved by other means (eg, stents).
Pearce
Jeffrey D
JD
Division of Surgical Sciences, Wake Forest University School of Medicine, Medical Center Boulevard, Winston-Salem, NC 27157, USA.
Li
Jing
J
Edwards
Matthew S
MS
English
William P
WP
Geary
Randolph L
RL
D019307:1-(5-Isoquinolinesulfonyl)-2-Methylpiperazine / Q000031:analogs & derivatives* / Q000494:pharmacology; D000818:Animals; D001011:Aorta; D002339:Carotid Arteries; D002478:Cells, Cultured; D003094:Collagen; D004305:Dose-Response Relationship, Drug; D004791:Enzyme Inhibitors / Q000494:pharmacology; D005782:Gels; D006965:Hyperplasia; D047908:Intracellular Signaling Peptides and Proteins; D008297:Male; D051379:Mice; D008810:Mice, Inbred C57BL; D009131:Muscle, Smooth, Vascular / Q000166:cytology / Q000502:physiology*; D017346:Protein Serine-Threonine Kinases / Q000037:antagonists & inhibitors* / Q000502:physiology; D017539:Tunica Intima / Q000166:cytology / Q000187:drug effects; D054460:rho-Associated Kinases
D004791:Enzyme Inhibitors; D005782:Gels; D047908:Intracellular Signaling Peptides and Proteins; D019307:1-(5-Isoquinolinesulfonyl)-2-Methylpiperazine; D003094:Collagen; D017346:Protein Serine-Threonine Kinases; D054460:rho-Associated Kinases; C049347:fasudil