This Article Full Text Full Text (PDF) Submit a response Alert me when this article is cited Alert me when eLetters are posted Alert me if a correction is posted Citation Map Services Email this article to a friend Similar articles in this journal Similar articles in PubMed Alert me to new issues of the journal Download to citation manager Request Permissions Citing Articles Citing Articles via HighWire Citing Articles via Google Scholar Google Scholar Articles by Hayakawa, Y. Articles by Fujiwara, H. Search for Related Content PubMed PubMed Citation Articles by Hayakawa, Y. Articles by Fujiwara, H. Related Collections Apoptosis Other arteriosclerosis Smooth muscle proliferation and differentiation

(Arteriosclerosis, Thrombosis, and Vascular Biology. 1999;19:2066-2077.)
© 1999 American Heart Association, Inc.

Vascular Biology

Apoptosis and Overexpression of Bax Protein and bax mRNA in Smooth Muscle Cells Within Intimal Hyperplasia of Human Radial Arteries

Analysis With Arteriovenous Fistulas Used for Hemodialysis

Yukihiro Hayakawa; Genzou Takemura; Jun Misao; Motoo Kanoh; Michiya Ohno; Hiroshige Ohashi; Hisato Takatsu; Hiroyasu Ito; Kazunori Fukuda; Takako Fujiwara; Shinya Minatoguchi; Hisayoshi Fujiwara
Abstract—There is a type of arteriosclerosis with remodeling of middle-size arteries in which intimal hyperplasia of smooth muscle cells (SMCs) plays the main role, and there are few macrophages, T lymphocytes, and foam cells. It is unknown whether apoptosis and the expression of Bax, an inducer of apoptosis, are increased according to the progression of this type of human arteriosclerosis, which is different from so-called atherosclerosis. Bax heterodimerizes with Bcl-2, an inhibitor of apoptosis, and the ratio of Bax to Bcl-2 determines cellular apoptosis or survival. Thus, we investigated apoptosis and the expressions of Bax, bax mRNA, and Bcl-2 in human arteriovenous (AV) fistulas used for hemodialysis, a representative of arteriosclerosis of the aforementioned type. The material was 20 radial arteries obtained from 20 patients with chronic renal failure undergoing AV shunt surgery. SMCs, macrophages, and T lymphocytes were immunohistochemically identified at the light microscopic (LM) level. Apoptosis was detected by in situ terminal deoxynucleotidyl transferase (TdT)–mediated digoxigenin-dUTP nick end labeling (TUNEL) at both the LM and electron microscopic (EM) level. Cell proliferating activity was estimated by proliferating cell nuclear antigen (PCNA). Bax and Bcl-2 were detected by immunohistochemistry and Western blot analysis. Expression of bax mRNA was detected by in situ hybridization. LM TUNEL-positive cells in both the intima and media were significantly increased according to the percent stenosis of the vessels. EM analysis revealed that ultrastructures of apoptotic SMCs were seen in both synthetic and contractile phenotypes. Their frequency of occurrence in the intima and media were greater in those vessels with >50% stenosis than in those with <50% stenosis (5.2±0.7% versus 1.0±0.3% in the intima and 2.1±0.5% versus 0.2±0.1% in the media). The proportion of apoptotic SMCs with ruptured plasma membranes was greater than that of apoptotic SMCs with intact membranes in the intima of the former (4.1±0.6% versus 1.1±0.1%). Only those SMCs with apoptotic ultrastructures had TUNEL-positive nuclei with moderate or marked accumulation of immunogold particles at the EM level. However, ultrastructures of oncosis (primary necrosis) were not observed. Immunohistochemical analyses showed significant positive correlations between percent stenosis of vessels and the percentage of either PCNA-positive intimal cells or Bax-positive areas in the intima and media. Bcl-2–positive cells were not observed in the intima but mainly in the outer media. The percentage of Bcl-2–positive medial cells was definitely decreased at an early stage after formation of the AV fistula but did not change according to the duration of hemodialysis or the progression of arteriosclerosis. Western blot analysis of Bax or Bcl-2 and in situ hybridization of bax mRNA confirmed the immunohistochemical data. Thus, regulation of cellularity in intimal hyperplasia of SMCs in human arteriosclerosis with remodeling is mediated by proliferation and apoptosis but not oncosis. The apoptosis is probably induced by an increase in the Bax to Bcl-2 ratio.

Key Words: apoptosis • arteriosclerosis • smooth muscle cells • Bax

This article has been cited by other articles:

				A. Orlandi, A. Francesconi, M. Marcellini, A. Di Lascio, and L. G. Spagnoli Propionyl-L-carnitine Reduces Proliferation and Potentiates Bax-related Apoptosis of Aortic Intimal Smooth Muscle Cells by Modulating Nuclear Factor-{kappa}B Activity J. Biol. Chem., February 16, 2007; 282(7): 4932 - 4942. [Abstract] [Full Text] [PDF]

				Y.-J. Geng and P. Libby Progression of Atheroma: A Struggle Between Death and Procreation Arterioscler Thromb Vasc Biol, September 1, 2002; 22(9): 1370 - 1380. [Abstract] [Full Text] [PDF]

				A. Orlandi, A. Francesconi, D. Cocchia, A. Corsini, and L. G. Spagnoli Phenotypic Heterogeneity Influences Apoptotic Susceptibility to Retinoic Acid and cis-Platinum of Rat Arterial Smooth Muscle Cells In Vitro : Implications for the Evolution of Experimental Intimal Thickening Arterioscler Thromb Vasc Biol, July 1, 2001; 21(7): 1118 - 1123. [Abstract] [Full Text] [PDF]