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Cardiovascular Research 2003 59(1):200-211; doi:10.1016/S0008-6363(03)00356-0
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Copyright © 2003, European Society of Cardiology

Angiotensin II type 1 receptor participates in extracellular matrix production in the late stage of remodeling after vascular injury

Hideyuki Eto, Sadatoshi Biro*, Masaaki Miyata, Hiroshi Kaieda, Hachiro Obata, Takashi Kihara, Koji Orihara and Chuwa Tei

The First Department of Internal Medicine, Faculty of Medicine, Kagoshima University, 8-35-1 Sakuragaoka, Kagoshima 890-8520, Japan

* Corresponding author. Tel.: +81-99-275-5318; fax: +81-99-275-5322. biro{at}m2.kufm.kagoshima-u.ac.jp

Received 22 November 2002; accepted 26 March 2003


   Abstract
Top
 Abstract
1. Introduction
 2. Methods
 3. Results
 4. Discussion
 5. Conclusions
 References
 
Objective: Extracellular matrix (ECM) accumulation is important in restenosis after angioplasty. Underlying molecular mechanisms remain to be elucidated, especially in vivo. We investigated expression of angiotensin II type 1 receptor (ATR1) in a rat model for up to 24 weeks after vascular injury, and also the effect of an ATR1 antagonist on neointimal thickening and ECM production. Methods and Results: Carotid arteries of rats were injured with a balloon catheter and then removed at 2, 5, and 7 days and 2, 4, 8, 16, and 24 weeks after injury. Although ATR1 immunoreactivity was slightly detectable in smooth muscle cells (SMC) in the media of uninjured arteries, reactivity was strong in neointimal SMC even 24 weeks after injury. Western blotting demonstrated similar results. ATR1 mRNA also was upregulated in neointimal SMC even 24 weeks after injury, as indicated by RT-PCR and by in situ hybridization. Candesartan, an ATR1 antagonist, significantly inhibited histologically evident neointimal thickening and collagen and elastin accumulation at 8 weeks after injury whether given beginning 1 day before injury, 4 days after injury, or 7 days after injury. Conclusion: ATR1 is upregulated in the late stage of remodeling after vascular injury and is important in ECM production.

KEYWORDS Angiotensin; Extracellular matrix; Receptors; Remodeling; Smooth muscle


   1. Introduction
Top
 Abstract
 1. Introduction
2. Methods
 3. Results
 4. Discussion
 5. Conclusions
 References
 
Percutaneous coronary intervention (PCI) is an important treatment for coronary artery disease. However, restenosis is a major problem, occurring within 6 months in about 30% of successful stent implantation [1]. Although a recent study showed that Sirolimus-eluting stents reduced restenosis rate to almost 0% [2], large-scale and long-term trial will be needed. One impediment to progress may be incomplete understanding of the mechanisms underlying restenosis. Restenosis is believed to result from a remodeling response to vascular injury.

Early events in vascular remodeling after injury include migration and proliferation of vascular smooth muscle cells (SMC); deposition of extracellular matrix (ECM) is a later occurrence [3–5]. Although extensive studies have focused on regulation of SMC proliferation [6–8], little is known about accumulation of ECM. SMC have been reported to produce ECM components in vitro [9,10] and in vivo [5], including collagen, elastin, and proteoglycans; thus, SMC are responsible for production of the ECM that contributes to intimal thickening after vascular injury [5]. Angiotensin II (A-II) is a well-known stimulus for production of the ECM components by SMC in vitro [11]. This stimulatory effect of A-II is mediated by angiotensin II type 1 receptor (ATR1) [12]. However, the level of receptor expression has not been elucidated in vascular remodeling after injury, especially in late stages. We investigated expression of A-II, ATR1, and angiotensin II type 2 receptor (ATR2), which is suggested to have the opposite of the function of ATR1, in rats and rabbits with balloon-induced injury to the carotid artery. Also, after observing that ATR1 was upregulated in intimal SMC even in the late stage after vascular injury, we used an ATR1 antagonist (ATR1A) to determine whether the additional ATR1 continues to function in inducing ECM production.


   2. Methods
Top
 Abstract
 1. Introduction
 2. Methods
3. Results
 4. Discussion
 5. Conclusions
 References
 
2.1 Animal models and study protocol
In the first experiment, 90 male Sprague–Dawley rats (300–400 g, 12 weeks old) were used. After rats were anesthetized by intraperitoneal injection of pentobarbital sodium (40 mg/kg), left common carotid arteries were injured by a 2Fr Fogarty catheter (Baxter Healthcare, Irvine, CA). At various time points (2, 5, and 7 days, and 2, 4, 8, 16, and 24 weeks after balloon injury) left common carotid arteries were carefully removed and fixed. Common carotid arterial lesions, representing areas not reendothelialized, were cut into three cross-sectional tissue blocks, and embedded in paraffin.

In the second experiment, 32 rats were divided into four groups. Group A (n = 8) underwent only vascular injury as described. Group B (n = 8) was treated with candesartan cilexetil (candesartan, an ATR1A; 10 mg/kg per day) for 8 weeks beginning 1 day before injury. Group C (n = 8) was treated with candesartan for 53 days beginning 4 days after injury. Group D (n = 8) was given with candesartan for 7 weeks beginning 7 days after injury, a delay intended to allow SMC to migrate and proliferate into the neointima. Just before sacrificed, the right carotid artery was cannulated with polyethylene tube and connected to polygraph system for measurement of the arterial blood pressure and heart rates. They were measured in all rats at 8 weeks after injury, and left common carotid arteries were carefully removed after sacrificed. Azan staining for collagen and Victoria blue staining for elastin were carried out to assess matrix production.

In both experiments, animals were treated in accordance with the Guide for Animal Experimentation of the Faculty of Medicine at Kagoshima University.

2.2 Morphometric histology
For measuring area of neointima, the circumferences of the lumen–intimal boundary (L) and the internal elastic lamina (I) were measured. The area of neointima was calculated as described previously [13].

2.3 Immunohistochemistry
Immunohistochemical staining of sections from tissues was performed as described previously [14]. Primary polyclonal antibodies used were anti-A-II (IgG, Nashville, TN), anti-ATR1, and anti-ATR2 (Santa Cruz Biotechnology, Santa Cruz, CA). The degree of ATR1 and ATR2 immunoreactivity was determined as a ratio of the number of positive staining cells to all cells in the area assessed (ratio/cm2). We defined a stained cell as one with reaction product occupying more than 50% of the area of the cytoplasm.

2.4 Western blotting
For Western blotting and reverse transcription-polymerase chain reaction (RT-PCR) of ATR1, eight male Japanese white rabbits weighing 3 to 3.5 kg were used. They were anesthetized and their aortas were injured by a 4Fr Fogarty catheter (Baxter Healthcare) as described above. Western blotting for determinant of ATR1 protein has been performed using anti-ATR1 (Santa Cruz Biotechnology) with actin as an internal control (anti-Actin, H-196, Santa Cruz Biotechnology) as described previously [14]. Densitometric analysis was performed to quantitate ATR1 protein and actin protein using NIH image software. Actin protein was used as a reference for quantitation of ATR1 protein.

2.5 RT-PCR
Total RNA at each time point was isolated by a guanidium thiocyanate method.

For synthesis of cDNA, 1 µg of total RNA was reverse-transcribed with random hexamer using Super Script II (Gibco-BRL, Life Technologies, Rockville, MD). The transcribed cDNA was amplified by PCR with specific primers for rabbit ATR1 and glyceraldehyde-3-phosphate dehydrogenase (GAPDH). Two specific primer pairs corresponding to published sequences were used [15]. Densitometric analysis was performed to quantitate PCR product using NIH image software. GAPDH expression was used as a reference for quantitation of ATR1 mRNA.

2.6 In situ hybridization
In situ hybridization was carried out with thymine–thymine (T–T) dimerized synthetic oligonucleotides complementary to a rat ATR1 mRNA as probes as reported previously [14].

A 45-base sequence (italic type) complementary to rat ATR1 mRNA (945–989) was chosen. A computer-assisted search (Genbank) of antisense sequences, as well as the sense sequences, revealed no significant homology with any known sequences other than that of ATR1. For haptenization of oligo-DNAs with T–T dimers, 2 or 3 TTA repeats were added to the 5'- and 3'- ends of the native sequences: antisense, 5'-TTATTAGTAATAGGCACTGACACTTTAACGACTGTAACACCTGTGGCGATAATTATTATT-3'; sense, 5'-TTATTACATTATCCGTGACTGTGAAATTGCTGACATTGTGGACACCGCTATATTATTATT-3'.

2.7 Statistical analysis
All calculated data were presented as the mean±S.D. and analyzed by ANOVA with repeated-measures. A value of P<0.05 was considered to indicate statistical significance.


   3. Results
Top
 Abstract
 1. Introduction
 2. Methods
 3. Results
4. Discussion
 5. Conclusions
 References
 
3.1 First experiment
3.1.1 Histology
Neointima appeared at 5 days after vascular injury, and the neointimal area increased until 8 weeks in rats (data not shown). Numbers of SMC (identified by immunohistochemical staining with anti-HHF-35 antibodies) increased from 5 to 7 days after vascular injury and then decreased as reported previously [13]. Almost all cells in the neointima were HHF-35 positive (data not shown). This time profile indicated that in the early phase, neointimal thickening was dependent on migration and proliferation of SMC, but became dependent on ECM production in the late phase.

3.1.2 Immunohistochemistry
Immunoreactivity for A-II was nearly undetectable in the media of uninjured vessels, but in the neointima reactivity appeared at 5 days, peaked at 7 days, gradually decreased after 2 weeks, and returned to baseline at 4 or 8 weeks in rats (Fig. 1). Immunoreactivity for ATR1 was slightly detectable in the media of uninjured vessels. Vascular injury induced much immunoreactivity in the neointima at 5 days with a peak between 1 and 4 weeks. ATR1 still stained strongly even at 16 and 24 weeks (Fig. 2). Interestingly, the time course of ATR2 immunoreactivity was almost similar to that of ATR1 (Fig. 3).


Figure 1
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  		Fig. 1 Immunohistochemical staining of angiotensin II (A-II) in the balloon-injured rat carotid artery. A-II were nearly undetectable in the media of uninjured vessels (a), but in the neointima A-II appeared at 5 days (c), peaked at 7 days (d), gradually decreased after 2 weeks (e), and returned to the baseline level at 4 (f) or 8 weeks (g). Other time points: (b) 2 days; (h) 16 weeks; and (i) 24 weeks after vascular injury. Arrows indicate internal elastic lamina.

 

Figure 2
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  		Fig. 2 Immunohistochemical staining of angiotensin II type 1 receptor (ATR1) in the balloon-injured rat carotid artery. (A) Immunoreactive ATR1 were slightly detectable in the media of an uninjured vessels (a). Vascular injury induced much immunoreactivity in the neointima beginning at 5 days (c), with a peak between 1 week (d) and 4 weeks (f). ATR1 were strongly stained even at 16 weeks (h) and 24 weeks (i). Other time points: (b) 2 days and (e) 2 weeks after vascular injury. Arrows indicate internal elastic lamina. (B) Ratio of cells staining for ATR1 to all cells per area (ratio/cm2, mean±S.D.). The ratio was significantly higher at 7 days to 24 weeks after vascular injury than at 5 days. Values are mean±S.D. *P<0.05 (compared to the ratio at 5 days).

 

Figure 3
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  		Fig. 3 Immunohistochemical staining of angiotensin II type 2 receptor (ATR2) in the balloon-injured rat carotid artery. (A) Immunoreactive ATR2 were undetectable in the media of an uninjured vessels (a). Vascular injury induced much immunoreactivity in the neointima beginning at 5 days (c), with a peak between 1 week (d) and 4 weeks (f). ATR2 were well stained even at 16 weeks (h) and 24 weeks (i). Other time points: (b) 2 days, (e) 2 weeks and (g) 8 weeks after vascular injury. Arrows indicate internal elastic lamina. (B) Ratio of cells staining for ATR2 to all cells per area (ratio/cm2, mean±S.D.). The ratio was significantly higher at 7 days to 24 weeks after vascular injury than at 5 days. Values are mean±S.D. *P<0.05 (compared to the ratio at 5 days).

 
3.1.3 Western blotting
Western analysis revealed that ATR1 protein was present in the media of uninjured arteries, was upregulated at 2 days after injury, and continued to gradually increase in the neointima and media up to 24 weeks after injury in rabbits (Fig. 4A,B).


Figure 4
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  		Fig. 4 Time course of induction of angiotensin II type 1 receptor (ATR1) protein and mRNA after balloon injury of the rabbit aortas. (A) Western blot showing a representative time-course assessment of ATR1 protein after vascular injury. Equal amounts of protein (20 µg) obtained from uninjured artery (cont) and balloon-injured artery at 2, 5, and 7 days (d), and at 2, 4, 8, 16, and 24 weeks (w) after balloon injury were electrophoresed on a gel. Actin served as an internal control. (B) Quantitation of ATR1 protein bands. Signal intensity of ATR1 protein was normalized to actin protein. Bar graph shows increases relative to uninjured aorta. (C) Reverse transcription-polymerase chain reaction (RT-PCR) showing a representative time-course assessment of ATR1 mRNA after vascular injury. RT-PCR product was isolated from uninjured aorta (cont) and balloon-injured aorta obtained at 2, 5, and 7 days (d), and 2, 4, 8, 16 and 24 weeks (w) after injury. Glyceraldehyde-3-phosphate dehydrogenase (GAPDH) served as an internal control. (D) Quantitation of ATR1 signals. Signal intensity of ATR1 was normalized to GAPDH. Bar graph shows increases relative to uninjured aorta.

 
3.1.4 RT-PCR
According to RT-PCR, ATR1 mRNA was expressed in uninjured arteries, was upregulated approximately 2-fold at 2 days after injury, and remained elevated compared with uninjured controls even at 16 and 24 weeks after injury in rabbits (Fig. 4C,D).

3.1.5 In situ hybridization
We also performed in situ hybridization to assess whether SMC produced mRNA encoding ATR1. Very few black dots representing reaction product could be detected in the media of uninjured vessels in rats (data not shown). In the neointima at 2 and 24 weeks after injury, more black dots were found (Fig. 5), indicating that neointimal SMC produced ATR1 mRNA.


Figure 5
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  		Fig. 5 In situ hybridization for angiotensin II type 1 receptor (ATR1) mRNA in rats carotid arteries. Using antisense probe, ATR1 mRNA was detected in smooth muscle cells of the media at 2 weeks (a) and even at 24 weeks (c) after vascular injury. Using sense probe, no signal was detected at 2 weeks (b) or 24 weeks (d). Arrows indicate internal elastic lamina.

 
3.2 Second experiment
3.2.1 Hemodynamic parameters
Candesartan significantly reduced arterial systolic blood pressure at 8 weeks after vascular injury in rats (76±20 vs. 137±7 mmHg, P<0.0001). Heart rates did not change by treatment with candesartan (264±52 v.s. 296±72 beats/min, N.S.).

3.2.2 Effect of candesartan cilexetil on neointimal thickening
Candesartan significantly inhibited neointimal thickening to the same degree in all three treatment regimens (beginning administration 1 day before injury, 4 days after injury, or 7 days after injury; Fig. 6).


Figure 6
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  		Fig. 6 Inhibition of neointimal thickening after vascular injury by candesartan in rats. (A) Neointimal thickening in the balloon-injured rat carotid artery. (a) Injured but untreated (group A). (b) Treatment with candesartan for 8 weeks beginning 1 day before injury (group B). (c) Treatment with candesartan for 53 days beginning 4 days after vascular injury (group C). (d) Treatment with candesartan for 7 weeks beginning 7 days after vascular injury (group D). (B) Effect of candesartan on neointimal thickening. All three treatment regimens significantly decreased neointimal thickening compared to the untreated group A (2.43±0.86, 2.26±0.74 and 2.80±0.48 vs. 4.15±0.63 mm2, mean±S.D., *P<0.001).

 
3.2.3 Effect of candesartan cilexetil on matrix production
Collagen formation detected by Azan staining was markedly inhibited in groups B, C, and D (Fig. 7b–d), compared with the untreated control group (Fig. 7a). Histological analysis with Victoria blue staining revealed a lattice-like pattern formed by elastin in the thickened intima in the control group not receiving candesartan (Fig. 7e). This pattern was lost in treated groups (B, C, and D; Fig. 7f–h).


Figure 7
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  		Fig. 7 Effect of candesartan on collagen and elastin production in rats. Collagen formation detected by Azan staining was markedly inhibited by all three treatment regimens (Group B:b, Group C:c, and Group D:d) compared to the untreated group A (a). A lattice-like pattern of elastin was shown in the thickened intima by Victoria blue staining in the untreated group A (e). This pattern was not seen in the three treated groups (Group B:f, Group C:g, and Group D:h). Treatment groups and schedules for group B, C, and D are as for Fig. 5. Arrows indicate internal elastic lamina.

 

   4. Discussion
Top
 Abstract
 1. Introduction
 2. Methods
 3. Results
 4. Discussion
5. Conclusions
 References
 
One major finding in this study is that a single vascular injury with a balloon catheter induced long-term expression of ATR1 in neointimal SMC, even at 24 weeks after injury. This induction was shown by immunohistochemistry, Western blotting, in situ hybridization, and RT-PCR. The other major finding is that blockade of these upregulated receptors with candesartan, an ATR1A, significantly inhibited neointimal thickening, apparently via inhibition of ECM production even when treatment was not begun until 7 days after vascular injury.

4.1 Importance of ECM deposition
Neointimal thickening and constrictive vascular remodeling are related to restenosis after vascular injury, including injury induced during PCI. Restenosis after stenting is caused by neointimal thickening made up SMC and increased ECM, as determined by histological analysis of lesion specimens obtained at atherectomy [16] or autopsy [17]. Moreover, intimal thickening with increased ECM is seen in the lesions of accelerated atherosclerosis, including vessels of transplanted hearts and bypass grafts [18]. Despite many trials of drugs intended to inhibit SMC proliferation, restenosis was not successfully prevented. One reason for failure may be our limited understanding of ECM production during neointimal thickening. The ECM in the thickened neointima after vascular injury is produced by SMC [6]. In vitro studies have shown that various growth factors such as platelet-derived growth factor (PDGF), A-II, and transforming growth factor β-1 (TGF β-1) stimulate SMC to produce ECM constituents such as collagen, elastin, and proteoglycans [7], and that the effect of A-II probably occurs via TGF β-1 [13]. In in vivo animal models, intravenous A-II infusion stimulates intimal thickening after vascular injury [11,19]. We also have observed that the active form of TGF β-1 was upregulated in neointima for 24 weeks after vascular injury (unpublished data). These observations suggest that in the present study, the ATR1A inhibited A-II-induced TGF β-1 expression, resulting in prevention of ECM deposition. We demonstrated histologically that lattice-like pattern of elastin was abolished and collagen deposition was markedly inhibited in the neointima by administration of ATR1A. An angiotensin I-converting enzyme (ACE) inhibitor and an ATR1A recently were reported to suppress neointimal formation in pulmonary artery injured by monocrotalin; suppression was associated with inhibition of gene expression for tropoelastin and procollagen [20]. Therefore, deposition of ECM plays an important role in neointimal thickening after vascular injury, representing an important target in prevention of restenosis.

4.2 Significance of long-term expression of ATR1 and ATR2
Expression of ATR1 and ATR2 previously had been investigated up to 2 weeks after vascular injury [21,22]. In this study we examined expression up to 24 weeks after injury. Surprisingly, ATR1 and ATR2 remained upregulated until 24 weeks. We found that ATR1A administration inhibited neointimal thickening and ECM deposition even at 8 weeks after vascular injury. This inhibitory effect indicates that the upregulated ATR1 indeed remained functional during this period. Further, administration of an ACE inhibitor, cilazapril, was found to significantly inhibit neointimal thickening at 52 weeks after injury [23] as judged by comparison with thickness at 2 or 8 weeks after vascular injury. This suggests the existence of functional ATR1 even at 52 weeks after a single vascular injury. Therefore, we think that one of the explanations for long-term expression of ATR1 is to synthesize extracellular matrix. In contrast, we speculate that upregulation of ATR2 may serve as a brake on upregulated ATR1 because the physiological function of ATR2 tends to oppose the action of ATR1 [24,25]. In the present study, we could not elucidate what caused the long-term expression of ATR1 and ATR2 after vascular injury. We suggest that various cytokines released after vascular injury may be involved, because these were reported to upregulate the expression of ATR1 [26]. Another possibility may be change of shear stress due to vascular remodeling after injury. Further examination will be needed.

4.3 Mechanisms of inhibition of neointimal thickening by an ATR1A
Our data, together with previous results mainly concerning the first 2 weeks after injury, indicate that ACE inhibitors and ATR1A inhibit neointimal thickening in both early [11,19,27,28] and late stages after vascular injury. A-II promotes migration and proliferation of SMC as well as production of ECM in SMC through ATR1 [24], while A-II inhibits migration and proliferation of SMC through ATR2 [25]. Neointimal thickening at 2 weeks after vascular injury has been attributed largely to migration and proliferation of SMC from the media.In the present study, ATR1A inhibited neointimal thickening even when treatment was not begun until 7 days after vascular injury. With such delayed treatment, SMC have time to migrate from the media and proliferate in the neointima. Therefore, we believe that successful inhibition of thickening depends largely on production of ECM including formation of abundant collagen and a lattice-like elastin pattern. Another interesting observation is that all three regimens of ATR1A treatment—beginning 1 day before injury, 4 days after injury, or 7 days after injury—inhibited neointimal thickening and histologically evident accumulation of ECM to the same degree. Treatment with an ATR1A has been found to increase the serum A-II concentration [29]. This additional circulating A-II can bind to angiotensin II type 2 receptors (ATR2). The physiological function of ATR2 tends to oppose the action of ATR1, such as inhibiting migration and proliferation of SMC [25], and mediating apoptosis of SMC [24,25]. However, the effects of ATR2 on ECM production remain controversial [30–32]. Therefore, one mechanism of inhibition of thickening by ATR1A might involve the action of increased amounts of A-II available to bind to ATR2.

A-II increases secretion of aldosterone, which can promote ECM formation [33]. Decreased secretion of aldosterone as a result of treatment with ATR1A might be another basis for inhibition of ECM production. Lowering blood pressure also should be considered. However, it has been already reported that the ACE inhibitor cilazapril suppressed neointimal formation after vascular injury in the rat carotid model by 70%, hydralazine suppressed by about 20% and the calcium antagonist verapamil did not suppress under the same condition in which blood pressure was lowered by approximately 20% [34].

4.4 Clinical implication and study limitation
In addition to ACE, chymase can generate A-II [35]. The relative contributions of ACE and chymase to production of A-II differ between species. In humans, 30% of A-II is produced by ACE and 70% by chymase [36]; in rats and rabbits, nearly 100% of A-II is produced by ACE [37]. In humans, then, an ACE inhibitor may have relatively little effect on total A-II production. On the other hand, ATR1A can inhibit the action of A-II irrespective of its enzymatic source. We expect that ATR1A will be clinically useful for inhibiting restenosis after vascular injury. However, caution is required in applying these animal data to the clinical setting. Doses of antagonist in animal studies have been much higher than acceptable doses in humans, and differences in distribution of ACE and chymase also need to be considered. We used rabbit arterial injury model for Western blotting and RT-PCR method, because much tissue was needed. Concerning differences of species, we have already observed that neointimal formation in rabbit model occurred in almost the same time-course as in rat model, and although at smaller number of time points, we have found that the time course of ATR1 expression was similar to that in rats by immunohistochemistry. In addition, as mentioned above, almost 100% of A-II is produced by ACE both in rats and rabbits. Since this study indicated that a single vascular injury induced long-term expression of functionally active ATR1 in neointimal SMC, long-term inhibition of the renin–angiotensin–aldosterone system would be required for inhibition of restenosis after vascular injury and progression of atherosclerosis.


   5. Conclusions
Top
 Abstract
 1. Introduction
 2. Methods
 3. Results
 4. Discussion
 5. Conclusions
References
 
ATR1 remains upregulated and contributes importantly to ECM production during the late stage of remodeling after vascular injury. Modifying this production and its regulation by ATR1 may represent a new approach to the prevention of restenosis after PTCA.

Time for primary review 31 days.

This study was in part presented at the XXI Congress of the European Society of Cardiology, 1999.


   Acknowledgements
 
This study was supported in part by the Scientific Research Grant from the Ministry of Education, Science, and Culture of Japan.


   References
Top
 Abstract
 1. Introduction
 2. Methods
 3. Results
 4. Discussion
 5. Conclusions
 References
 

  1. Radke P.W., Kaiser A., Frost C., Sigwart U. Outcome after treatment of coronary in-stent restenosis. Results from a systematic review using meta-analysis techniques. Eur Heart J. (2003) 24:266–273.[Abstract/Free Full Text]
  2. Morice M.C., Serruys P.W., Sousa J.D., Fajadet J., Hayashi E.B., Perin M., Colombo A., Schuler G., Barragan P., Guagliumi G., Molnar F., Falotico R. The Ravel Study Group. A randomized comparison of a Sirolimus-eluting stent with a standard stent for coronary revascularization. New Engl J Med (2002) 346:1773–1780.[Abstract/Free Full Text]
  3. Jesse W.C., David P.F. Animal models of restenosis. In: Coronary restenosis—Schwartz R.S., ed. (1993) Boston, MA: Blackwell Scientific Publications. 293–324.
  4. Kenneth C.H., Kirk N.G., Robert S.S., William D.E. Pathology of postinterventional coronary restenosis. In: Coronary restenosis—Schwartz R.S., ed. (1993) Boston, MA: Blackwell Scientific Publications. 192–204.
  5. Nikkari S.T., Jarvelainen H.T., Wight T.N., Ferguson M., Clowes A.W. Smooth muscle cell expression of extracellular matrix genes after arterial injury. Am J Pathol (1994) 144:1348–1356.[Abstract]
  6. Clowes A.W., Clowes M.M., Fingerle J., Reidy M.A. Regulation of smooth muscle cell growth in injured artery. J Cardiovasc Pharmacol (1989) 14(Suppl. 6):S12–15.
  7. Casscells W. Smooth muscle cell growth factors. Prog Growth Factor Res. (1991) 3:177–206.[CrossRef][Medline]
  8. Newby A.C., Zaltsman A.B. Molecular mechanisms in intimal hyperplasia. J Pathol (2000) 190:300–309.[CrossRef][ISI][Medline]
  9. Narayanan A.S., Sandberg L.B., Ross R., Layman D.L. The smooth muscle cell. III. Elastin synthesis in arterial smooth muscle cell culture. J Cell Biol (1976) 68:411–419.[Abstract/Free Full Text]
  10. Burke J.M., Balian G., Ross R., Bornstein P. Synthesis of type I and III procollagen and collagen by monkey aortic smooth muscle cells in vitro. Biochemistry (1977) 16:3243–3249.[CrossRef][ISI][Medline]
  11. Osterrieder W., Muller R.K., Powell J.S., Clozel J.P., Hefti F., Baumgartner H.R. Role of angiotensin II injury-induced neointimal formation in rats. Hypertension (1991) 18(Suppl. 4):II60–64.[Medline]
  12. Ford C.M., Li S., Pickering J.G. Angiotensin II stimulated collagen synthesis in human vascular smooth muscle cells. Involvement of the AT(1) receptor, transforming growth factor-beta, and tyrosine phosphorylation. Arterioscler Thromb Vasc Biol (1999) 19:1843–1851.[Abstract/Free Full Text]
  13. Clowes A.W., Reidy M.A., Clowes M.M. Mechanisms of stenosis after arterial injury. Lab Invest (1983) 49:208–215.[ISI][Medline]
  14. Miyata M., Biro S., Kaieda H., Eto H., Orihara K., Kihara T., Obata H., Matsushita N., Matsuyama T., Tei C. Apolipoprotein J/Clusterin is induced in vascular smooth muscle cells after vascular injury. Circulation (2001) 104:1407–1412.[Abstract/Free Full Text]
  15. Yang B.C., Phillips M.I., Mohuczy D., Meng H., Shen L., Mehta P., Mehta J.L. Increased angiotensin II type 1 receptor expression in hypercholesterolemic atherosclerosis in rabbits. Arterioscler Thromb Vasc Biol (1998) 18:1433–1439.[Abstract/Free Full Text]
  16. Moreno P.R., Palacious I.F., Leon M.N., Rhodes J., Fuster V., Fallon J.T. Histopathologic comparison of human coronary in-stent and post-balloon angioplasty restenotic tissue. Am J Cardiol (1999) 84:462–466.[CrossRef][ISI][Medline]
  17. Grewe P.H., Deneke T., Machraoui A., Barmeyer J., Muller K.M. Acute and chronic response to coronary stent implantation: pathologic findings in human specimen. J Am Coll Cardiol (2000) 35:157–163.[Abstract/Free Full Text]
  18. Ip J.H., Fuster V., Badimon L., Badimon J., Taubman M.B., Chesebro J.H. Syndrome of accelerated atherosclerosis: role of vascular injury and smooth muscle cell proliferation. J Am Coll Cardiol (1990) 15:1667–1687.[Abstract]
  19. Janiak P., Libert O., Vilaine J.P. Role of the renin-angiotensin system in neointima formation after injury in rabbits. Hypertension (1994) 24:671–678.[Abstract/Free Full Text]
  20. Okada K., Bernstein M.L., Zhang W., Schuster D.P., Botney M.D. Angiotensin-converting enzyme inhibition delays pulmonary vascular neointimal formation. Am J Respir Crit Care Med (1998) 158:939–950.[Abstract/Free Full Text]
  21. Viswanathan M., Strouberg C., Seltzer A., Saavedra J.M. Balloon angioplasty enhances the expression of angiotensin II AT1 receptors in neointima of rat aorta. J Clin Invest (1992) 90:1707–1712.[ISI][Medline]
  22. Janiak P., Pillon A., Prost J.F., Vilaine J.P. Role of angiotensin subtype 2 receptor in neointima formation after vascular injury. Hypertension (1992) 20:737–745.[Abstract/Free Full Text]
  23. Fingerle J., Muller R.M., Kuhn H., Pech M., Baumgartner H.R. Mechanism of inhibition of neointimal formation by the angiotensin-converting enzyme inhibitor cilazapril. A study in balloon catheter-injured rat carotid arteries. Arterioscler Thromb Vasc Biol (1995) 15:1945–1950.[Abstract/Free Full Text]
  24. Dinh D.T., Frauman A.G., Johnston C.I., Fabiani M.E. Angiotensin receptors: distribution, signaling and function. Clin Sci (2001) 100:481–492.[CrossRef][ISI][Medline]
  25. Horiuchi M., Akishita M., Dzau V.J. Recent progress in angiotensin II type 2 receptor research in the cardiovascular system. Hypertension (1999) 33:613–621.[Abstract/Free Full Text]
  26. Nickenig G., Harrison D.G. The AT(1)-type angiotensin receptor in oxidative stress and atherogenesis: Part II: AT(1) receptor regulation. Circulation (2002) 105:530–536.[Free Full Text]
  27. Powell J.S., Clozel J.P., Muller R.K. Inhibitors of angiotensin-converting enzyme prevent myointimal proliferation after vascular injury. Science (1989) 14(245):186–188.
  28. Miyazaki M., Shiota N., Sakonjo H., Takai S. Angiotensin II type 1 receptor antagonist, TCV-116, prevents neointima formation in injured arteries in the dog. Jpn J Pharmacol (1999) 79:455–460.[CrossRef][Medline]
  29. Nagano M., Higaki J., Mikami H., Ogihara T. Role of the renin-angiotensin system in hypertension in the elderly. Blood Press Suppl (1994) 5:30–33.
  30. Levy B.I., Benessiano J., Henrion D., Caputo L., Heymes C., Micheline D., Poitevin P., Samuel J.L. Chronic blockade of AT2-subtype receptors prevents the effect of angiotensin II on the rat vascular structure. J Clin Invest (1996) 98:418–425.[ISI][Medline]
  31. Li J.S., Touyz R.M., Schiffrin E.L. Effect of AT1 and AT2 angiotensin receptor antagonists in angiotensin II-infused rats. Hypertension (1998) 31:487–492.[Abstract/Free Full Text]
  32. Mifune M., Sasamura H., Shimizu-Hirota R., Miyazaki H., Saruta T. Angiotensin II type 2 receptor stimulate collagen synthesis in cultured vascular smooth muscle cells. Hypertension (2000) 36:845–850.[Abstract/Free Full Text]
  33. Benetos A., Lacolley P., Safar M.E. Prevention of aortic fibrosis by spironolactone in spontaneously hypertensive rats. Arterioscler Thromb Vasc Biol (1997) 17:1152–1156.[Abstract/Free Full Text]
  34. Powell J.S., Muller R.K., Baumgartner H.R. Suppression of the vascular response to injury: the role of Angiotensin-converting enzyme inhibitors. J Am Coll Cardiol (1991) 17(Suppl. B 6):137B–142B.[Medline]
  35. Nishimura H., Hoffman S., Beltatu O., Sugimura K., Ganten D., Urata H. Angiotensin I converting enzyme and chymase in cardiovascular tissues. Kidney Int Suppl (1996) 55:S18–23.[CrossRef][Medline]
  36. Okunishi H., Oka Y., Shiota N., Kawamoto T., Song K., Miyazaki M. Marked species-difference in the vascular angiotensin II-forming pathways: humans versus rodents. Jpn J Pharmacol (1993) 62:207–210.[Medline]
  37. Jin D., Takai S., Yamada M., Sakaguchi M., Miyazaki M. The functional ratio of chymase and angiotensin converting enzyme in angiotensin I-induced vascular contraction in monkeys, dogs and rats. Jpn J Pharmacol (2000) 84:449–454.[CrossRef][Medline]

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