Caplice N M, Mueske C S, Kleppe L S, Peterson T E, Broze G J, Simari R D
Divisions of Cardiovascular Diseases and Biochemistry and Molecular Biology, Molecular Medicine Program, Mayo Clinic and Foundation, Rochester, MN, USA.
Circ Res. 1998;83(12):1264-70. doi: 10.1161/01.res.83.12.1264.
Tissue factor pathway inhibitor (TFPI) in vivo is thought to be synthesized mainly by endothelial cells. To date, no significant regulator of TFPI synthesis has been described. Vascular smooth muscle cells (VSMC) express tissue factor in vitro and in vivo, which may contribute to vascular thrombosis. We hypothesized that VSMC might also express TFPI. To determine this, we examined growth-arrested coronary VSMC in culture and found that VSMC secreted an amount of TFPI similar to that seen in endothelial cells. Immunohistochemistry of normal human coronary arteries showed TFPI staining throughout the media and intima of the vessel with localization to VSMC and endothelial cells. To determine regulation of TFPI expression in VSMC, we examined the effects of serum stimulation on TFPI secretion and found that FBS induced a 5-fold increase in TFPI antigen and activity levels in conditioned medium at 48 hours (P<0.001) when compared with serum-free conditions. A similar stimulatory effect was seen with 10% pooled human serum. Moreover, epidermal growth factor and platelet-derived growth factor-B increased TFPI secretion by 4- to 5-fold and 2- to 3-fold, respectively (P<0.05), and these growth factors accounted for approximately 50% of the TFPI secretion effects of human serum. The serum effect was associated with a 3-fold increase in TFPI mRNA 24 hours after release from growth arrest and a 50% decrease in TFPI secretion after treatment with actinomycin D. Taken together, this study suggests that there is significant TFPI expression in VSMC in culture and in VSMC within the intima and media of the normal coronary artery wall. We present the first evidence for TFPI regulation by serum in VSMC and more specifically by its constituent growth factors, epidermal growth factor and platelet-derived growth factor-B.
组织因子途径抑制物（TFPI）在体内被认为主要由内皮细胞合成。迄今为止，尚未发现TFPI合成的重要调节因子。血管平滑肌细胞（VSMC）在体外和体内均表达组织因子，这可能导致血管血栓形成。我们推测VSMC也可能表达TFPI。为了确定这一点，我们检测了培养中生长停滞的冠状动脉VSMC，发现VSMC分泌的TFPI量与内皮细胞相似。正常人冠状动脉的免疫组织化学显示，TFPI染色遍布血管的中膜和内膜，定位于VSMC和内皮细胞。为了确定VSMC中TFPI表达的调节机制，我们检测了血清刺激对TFPI分泌的影响，发现与无血清条件相比，胎牛血清（FBS）在48小时时使条件培养基中的TFPI抗原和活性水平增加了5倍（P<0.001）。10%的混合人血清也有类似的刺激作用。此外，表皮生长因子和血小板衍生生长因子-B分别使TFPI分泌增加了4至5倍和2至3倍（P<0.05），这些生长因子约占人血清TFPI分泌作用的50%。血清作用与生长停滞解除24小时后TFPI mRNA增加3倍以及放线菌素D处理后TFPI分泌减少50%有关。综上所述，本研究表明培养中的VSMC以及正常冠状动脉壁内膜和中膜中的VSMC存在显著的TFPI表达。我们首次提供了血清对VSMC中TFPI调节的证据，更具体地说是其组成生长因子表皮生长因子和血小板衍生生长因子-B对TFPI的调节证据。
