Shear stress as an inhibitor of vascular smooth muscle cell proliferation. Role of transforming growth factor-beta 1 and tissue-type plasminogen activator.
We examined whether shear stress can inhibit vascular smooth muscle cell (VSMC) proliferation in vitro directly. Human VSMCs were exposed to fluid flow for 24 hours using a cone-plate apparatus, and their proliferation was inhibited significantly by shear stresses of 1.4 and 2.8 Pa (14 and 28 dyne/cm2), according to the magnitude. Next, we investigated whether transforming growth factor-beta 1 (TGF beta 1), which is known to be an important cytokine that suppresses VSMC proliferation, is the predominant mediator of shear-induced inhibition of VSMC growth. After exposure of VSMCs to shear stress (2.8 Pa) for 24 hours, gene expression of TGF beta 1 and, interestingly, tissue-type plasminogen activator, which converts plasminogen to plasmin, an activator of TGF beta 1, increased twofold and fivefold, respectively. The levels of both latent and active forms of TGF beta 1 in conditioned media of VSMCs exposed to fluid flow increased significantly. An anti-TGF beta 1 antibody reversed shear-induced inhibition of VSMC growth significantly. We concluded that shear stress inhibited VSMC proliferation in vitro and this inhibition was mediated predominantly by TGF beta 1 in an autocrine manner. These data suggest that shear stress plays an important role as an inhibitor of atherogenesis in endothelium-desquamated lesions.
Ueba
H
H
Department of Internal Medicine, Omiya Medical Center, Jichi Medical School, Japan.
Kawakami
M
M
Yaginuma
T
T
D000906:Antibodies / Q000494:pharmacology; D002455:Cell Division / Q000187:drug effects / Q000276:immunology / Q000502:physiology; D017077:Culture Media, Conditioned / Q000737:chemistry; D016895:Culture Media, Serum-Free / Q000737:chemistry; D006801:Humans; D007074:Immunoglobulin G / Q000494:pharmacology; D024510:Muscle Development; D009131:Muscle, Smooth, Vascular / Q000166:cytology* / Q000254:growth & development; D012333:RNA, Messenger / Q000378:metabolism; D013314:Stress, Mechanical; D010959:Tissue Plasminogen Activator / Q000235:genetics / Q000502:physiology; D016212:Transforming Growth Factor beta / Q000235:genetics / Q000276:immunology / Q000502:physiology
D000906:Antibodies; D017077:Culture Media, Conditioned; D016895:Culture Media, Serum-Free; D007074:Immunoglobulin G; D012333:RNA, Messenger; D016212:Transforming Growth Factor beta; D010959:Tissue Plasminogen Activator