Introduction Directory UMM :Data Elmu:jurnal:A:Atherosclerosis:Vol152.Issue1.Sep2000:

Atherosclerosis 152 2000 97 – 105 Expression of parathyroid hormone-related protein in human and experimental atherosclerotic lesions: functional role in arterial intimal thickening Michiro Ishikawa a,b , Masahiro Akishita a , Koichi Kozaki a , Kenji Toba a , Atsushi Namiki b , Tetsu Yamaguchi b , Hajime Orimo a , Yasuyoshi Ouchi a, a Department of Geriatric Medicine, Graduate School of Medicine, The Uni6ersity of Tokyo, 7 - 3 - 1 Hongo, Bunkyo-ku, Tokyo 113 - 8655 , Japan b Third Department of Internal Medicine, Toho Uni6ersity School of Medicine, Ohashi Hospital, 2 - 17 - 6 Ohashi, Meguro-ku, Tokyo 153 , Japan Received 16 February 1999; received in revised form 14 September 1999; accepted 3 November 1999 Abstract We investigated the expression of parathyroid hormone-related protein PTHrP in atherosclerotic lesions and the role of PTHrP in the development of arterial neointima formation. Immunohistochemical staining of PTHrP in the neointima of rat aorta produced by balloon injury and of rat femoral artery produced by non-obstructive polyethylene cuff placement, and in the atherosclerotic lesion of human coronary artery was performed using anti-human PTHrP-1-34 antibody. Anti-muscle actin antibody, HHF-35, and anti-macrophage antibody, HAM-56, were used to identify smooth muscle cells and macrophages, respectively. Immunoreactivity of PTHrP was detected in the thickened intima of rat and human lesions where the predominant cell types were smooth muscle cells or macrophages dependently on the lesion type. In the next series of experiments, we examined the effect of PTHrP on the development of cuff-induced intimal thickening of rat femoral artery. Either PTHrP-1-34 or PTHrP-7-34, a PTHPTHrP receptor antagonist, suspended in pluronic F-127 gel was locally applied around the rat femoral artery. Intimal thickening induced by cuff placement was evaluated 2 weeks later. PTHrP-1-34 dose-dependently inhibited intimal thickening determined as intimamedia ratio and stenosis whereas PTHrP-7-34 dose-dependently enhanced that. These results suggest that PTHrP, which is expressed in atherosclerotic lesions, inhibits the development of neointimal formation. © 2000 Elsevier Science Ireland Ltd. All rights reserved. Keywords : Parathyroid hormone-related protein; Vascular smooth muscle cell; Immunohistochemistry; Atherosclerosis; Neointima www.elsevier.comlocateatherosclerosis

1. Introduction

Atherosclerosis is characterized by arterial luminal narrowing associated with thickening of the arterial intima. Similar pathological changes have been demon- strated at the restenotic site of coronary arteries after angioplasty or atherectomy [1,2]. A large number of biologically active substances such as growth factors, cytokines and vasoactive peptides have been considered to play an important role in the atherogenic and restenotic processes [3,4]. Since the discovery of platelet-derived growth factor [5], various substances with atherogenic properties have been identified and their relation with the development of atherosclerosis or restenosis has been extensively investigated. However, the information concerning the role of vasoactive sub- stances with anti-atherogenic property in this process is scanty. Parathyroid hormone-related protein PTHrP was originally identified in human tumor tissues as a causative factor of the syndrome of humoral hypercal- cemia of malignancy [6 – 11]. The presence of PTHrP has been demonstrated not only in tumor tissues but also in a variety of tissues [12 – 14]. Some recent reports have shown that PTHrP is expressed in vascular smooth muscle cells VSMCs [15] and vascular en- Corresponding author. Tel.: + 81-3-5800-8830; fax: + 81-3-5800- 6529. E-mail address : youchi-tkyumin.ac.jp Y. Ouchi. 0021-915000 - see front matter © 2000 Elsevier Science Ireland Ltd. All rights reserved. PII: S 0 0 2 1 - 9 1 5 0 9 9 0 0 4 5 5 - 4 dothelial cells [16,17], and a common receptor for parathyroid hormone PTH and PTHrP exists in vas- cular smooth muscle [18]. However, there have been few reports demonstrating the expression of PTHrP in the thickened intima of atherosclerotic and restenotic lesions [19,20]. Moreover, the pathophysiological role of PTHrP in the vascular wall, either in the normal or diseased state, has not been elucidated. PTHrP has a potent vasodilator action [21 – 24] which is associated with increased production of cyclic AMP and decreased intracellular free calcium concentration in vascular smooth muscle [24]. Also, PTHrP exhibits an inhibitory effect on VSMC migration and prolifera- tion [25]. These actions of PTHrP and its expression in a variety of tissues have led us to examine the expres- sion of PTHrP and its pathophysiological role in atherosclerotic lesions. Here we report that PTHrP is expressed in human atherosclerotic lesions as well as experimentally produced neointimal lesions. Further- more, we demonstrate that locally administered PTHrP inhibits and PTHrP antagonist enhances intimal thick- ening induced by non-obstructive polyethylene cuff in rats.

2. Materials and methods