Douillet C D, Velarde V, Christopher J T, Mayfield R K, Trojanowska M E, Jaffa A A
Department of Medicine, Medical University of South Carolina, Charleston, USA.
Am J Physiol Heart Circ Physiol. 2000 Dec;279(6):H2829-37. doi: 10.1152/ajpheart.2000.279.6.H2829.
Accumulation of extracellular matrix (ECM) is a hallmark feature of vascular disease. We have previously shown that hyperglycemia induces the expression of B(2)-kinin receptors in vascular smooth muscle cells (VSMC) and that bradykinin (BK) and hyperglycemia synergize to stimulate ECM production. The present study examined the cellular mechanisms through which BK contributes to VSMC fibrosis. VSMC treated with BK (10(-8) M) for 24 h significantly increased alpha(2)(I) collagen mRNA levels. In addition, BK produced a two- to threefold increase in alpha(2)(I) collagen promoter activity in VSMC transfected with a plasmid containing the alpha(2)(I) collagen promoter. Furthermore, treatment of VSMC with BK for 24 h produced a two- to threefold increase in the secretion rate of tissue inhibitor of metalloproteinase 1 (TIMP-1). The increase in alpha(2)(I) collagen mRNA levels and alpha(2)(I) collagen promoter activity, as well as TIMP-1 secretion, in response to BK were blocked by anti-transforming growth factor-beta (anti-TGF-beta) neutralizing antibodies. BK (10(-8) M) increased the endogenous production of TGF-beta1 mRNA and protein levels. Inhibition of the mitogen-activated protein kinase (MAPK) pathway by PD-98059 inhibited the increase of alpha(2)(I) collagen promoter activity, TIMP-1 production, and TGF-beta1 protein levels observed in response to BK. These findings provide the first evidence that BK induces collagen type I and TIMP-1 production via autocrine activation of TGF-beta1 and implicate MAPK pathway as a key player in VSMC fibrosis in response of BK.
细胞外基质（ECM）的积累是血管疾病的一个标志性特征。我们之前已经表明，高血糖会诱导血管平滑肌细胞（VSMC）中B（2）-激肽受体的表达，并且缓激肽（BK）和高血糖协同刺激ECM的产生。本研究探讨了BK促进VSMC纤维化的细胞机制。用BK（10^(-8) M）处理VSMC 24小时可显著增加α2（I）型胶原mRNA水平。此外，BK使转染了含有α2（I）型胶原启动子质粒的VSMC中的α2（I）型胶原启动子活性增加了两到三倍。此外，用BK处理VSMC 24小时使金属蛋白酶组织抑制剂1（TIMP-1）的分泌率增加了两到三倍。抗转化生长因子-β（抗-TGF-β）中和抗体可阻断BK诱导的α2（I）型胶原mRNA水平、α2（I）型胶原启动子活性以及TIMP-1分泌的增加。BK（10^(-8) M）增加了TGF-β1 mRNA的内源性产生和蛋白质水平。用PD-98059抑制丝裂原活化蛋白激酶（MAPK）途径可抑制BK诱导的α2（I）型胶原启动子活性、TIMP-1产生和TGF-β1蛋白质水平的增加。这些发现首次证明BK通过TGF-β1的自分泌激活诱导I型胶原和TIMP-1的产生，并表明MAPK途径是BK诱导VSMC纤维化的关键因素。
