No abstract

We investigated the effect of a chymase inhibitor Suc-Val-Pro-Phe(P)(OPh)(2) on the proliferation of the grafted vein in dog. By 28 days after the operation, the mean intimal area of the grafted vein in the placebo group was 3.24+/-0.32 mm(2). The intimal area of the grafted vein in the chymase inhibitor-treated group was reduced to 63.9%. In the placebo group, the activities of chymase and angiotensin-converting enzyme in grafted vein were significantly increased 15- and 2-fold, respectively. In the chymase inhibitor-treated group, chymase activity in the grafted veins was decreased significantly. These findings suggest that inhibition of chymase appears useful for preventing vascular proliferation.

Background Vascular tissues of humans and dogs contain chymase as an angiotensin II–forming enzyme. In this study, we investigated whether chymase-dependent angiotensin II formation plays a crucial role in the development of vascular proliferation in dog grafted veins. Methods and Results The right external jugular vein of dogs was grafted to the ipsilateral carotid artery. As a control group, the right external jugular veins in dogs that had not received grafts were used. In the chymase inhibitor–treated group, the vein was infiltrated with 10 μmol/L Suc-Val-Pro-Phe P (OPh) 2 and was grafted to the carotid artery. In the placebo-treated group, ACE activity in the grafted veins was significantly lower than that in the control veins up to 7 days after the operation, whereas chymase activity was increased significantly. After 7 days, the mRNA levels of collagen I, collagen III, and fibronectin, all of which are induced by an increase of angiotensin II action, were significantly increased in the grafted veins, and the intima-media ratio of the grafted veins was also increased. In the chymase inhibitor–treated group, the chymase activity in the grafted veins 7 days after the operation was suppressed to 12.1%. The elevated mRNA levels of fibronectin, collagen I, and collagen III in the grafted veins were significantly suppressed by treatment with the chymase inhibitor, and the intima-media ratio was also decreased significantly. Conclusions We demonstrate for the first time that chymase-dependent angiotensin II formation plays an important role in the development of vascular proliferation in the grafted veins.

Wnt5a, a member of the noncanonical Wnt proteins, is known to play important roles in the development of various organs and in postnatal cell functions. However, little is known about the effects of Wnt5a on human periodontal ligament (PDL) cells. In this study, we examined the localization and potential function of Wnt5a in PDL tissue. Immunohistochemical analysis revealed that Wnt5a was expressed predominantly in rat PDL tissue. Semi-quantitative reverse-transcription polymerase chain reaction and Western blotting analysis demonstrated that human PDL cells (HPDLCs) expressed Wnt5a and its receptors (Ror2, Fzd2, Fzd4, and Fzd5). Removal of occlusal pressure by extraction of opposing teeth decreased Wnt5a expression in rat PDL tissue, and the expression of Wnt5a and its receptors in HPDLCs was upregulated by exposure to mechanical stress. Stimulation with Wnt5a significantly enhanced the proliferation and migration of HPDLCs. Furthermore, Wnt5a suppressed osteoblastic differentiation of HPDLCs cultivated in osteogenic induction medium, while it significantly enhanced the expression of PDL-related genes, such as periostin, type-I collagen, and fibrillin-1 genes, and the production of collagen in HPDLCs cultivated in normal medium. Both knockdown of periostin gene expression by siRNA and inhibition of TGFβ1 function by neutralizing antibody suppressed the Wnt5a-induced PDL-related gene expression and collagen production in HPDLCs. Interestingly, in HPDLCs cultured with Wnt5a, TGFβ1 neutralizing antibody significantly suppressed periostin expression, while periostin siRNA had no effect on TGFβ1 expression. These results suggest that Wnt5a expressed in PDL tissue plays specific roles in inducing collagen production by PDL cells through TGFβ1-mediated upregulation of periostin expression.