Donate Help Contact The AHA Sign In Home
American Heart Association
Circulation Research
Search: search_blue_button Advanced Search
Circulation Research. 1997;80:490-496

This Article
Right arrow Abstract Freely available
Right arrow Alert me when this article is cited
Right arrow Alert me if a correction is posted
Right arrow Citation Map
Services
Right arrow Email this article to a friend
Right arrow Similar articles in this journal
Right arrow Similar articles in PubMed
Right arrow Alert me to new issues of the journal
Right arrow Download to citation manager
Right arrow Request Permissions
Citing Articles
Right arrow Citing Articles via HighWire
Right arrow Citing Articles via Google Scholar
Google Scholar
Right arrow Articles by Hasenstab, D.
Right arrow Articles by Clowes, A. W.
Right arrow Search for Related Content
PubMed
Right arrow PubMed Citation
Right arrow Articles by Hasenstab, D.
Right arrow Articles by Clowes, A. W.
(Circulation Research. 1997;80:490-496.)
© 1997 American Heart Association, Inc.


Articles

Plasminogen Activator Inhibitor Type 1 and Tissue Inhibitor of Metalloproteinases-2 Increase After Arterial Injury in Rats

David Hasenstab, Reza Forough, , Alexander W. Clowes

From the Departments of Pathology (D.H.) and Surgery (R.F., A.W.C.), University of Washington, Seattle.


*    Abstract
up arrowTop
*Abstract
down arrowIntroduction
down arrowMaterials and Methods
down arrowResults
down arrowDiscussion
down arrowReferences
 
Abstract Vascular injury induced by angioplasty causes smooth muscle cells to migrate, proliferate, and form a neointima. The neointima is further enlarged by the accumulation of matrix molecules synthesized by smooth muscle cells. Smooth muscle cell migration and matrix accumulation are associated with an increase in the expression of matrix-degrading enzymes and might be regulated by the balance of protease and anti-protease activity. We have studied the inhibitors of two major classes of matrix-degrading enzymes, the plasminogen activators and the matrix metalloproteinases (MMPs) to understand better the regulation of proteolytic activity following balloon catheter injury in the rat carotid artery. At various times after injury, protease inhibitor expression was analyzed by Northern blotting, reverse zymography, immunohistochemistry, and Western blotting. During the first month after injury, we found that the expression of two proteinase inhibitors (plasminogen activator inhibitor type 1 [PAI-1] and tissue inhibitor of metalloproteinases-2 [TIMP-2]) was modulated. PAI-1 mRNA expression reached a maximum 6 hours after injury before tapering off to baseline levels by 3 days. PAI-1 activity, as measured by reverse zymography, followed the same temporal profile. PAI-1, localized by immunohistochemistry, was expressed at low levels in the media of control arteries and was increased after injury primarily in the medial smooth muscle cells. TIMP-2 mRNA levels began to increase 24 hours after injury and reached a maximum at day 7. TIMP-2 activity, measured by reverse zymography, peaked at day 3 after injury. TIMP-2 protein was increased in the intima compared with the media and adventitia at day 7 after injury. The increase of PAI-1 and TIMP-2 after injury supports the hypothesis that changes in the proteolytic balance play an important role in smooth muscle cell migration after arterial injury.


Key Words: smooth muscle cell • plasminogen activator inhibitor type 1 • tissue inhibitor of metalloproteinases-2 • protease • arterial injury


*    Introduction
up arrowTop
up arrowAbstract
*Introduction
down arrowMaterials and Methods
down arrowResults
down arrowDiscussion
down arrowReferences
 
Cell migration is a central event in many biological processes. Tumor invasion, development, and tissue remodeling all require carefully controlled cell migration. Migration of vascular SMCs plays a major role in the formation of arterial intimal lesions in human atherosclerosis and the formation of the neointima associated with restenosis following balloon angioplasty.1 SMCs in the arterial wall are surrounded by ECM composed of collagen, fibronectin, proteoglycans, and other glycoproteins. SMCs, in order to migrate, must detach themselves from this surrounding cage of ECM by proteolytic degradation of their pericellular matrix.

Vascular SMCs are known to produce both serine proteases and MMPs. These proteases are capable of degrading all the components of the ECM. Plasmin, a serine protease, is formed from plasminogen by PAs (tissue PA and urokinase PA). Studies from this as well as other laboratories have shown that PA activity increases after balloon injury and that by blocking plasmin generation, neointima formation is reduced.2 3 Plasmin is a serine protease of broad specificity that is also able to activate other MMPs as well as degrade matrix. Plasmin generation is primarily controlled by the balance between the PAs and their physiological inhibitors, the PAIs. In addition to PAs, MMPs are produced by vascular SMCs in response to balloon injury.4 5 Inhibition of MMP activity reduces neointima formation5 and limits invasiveness in tumor invasion models.6 7 8 These previous results show that inhibiting protease activity can limit neointima formation and suggest that protease inhibitors may serve to regulate SMC migration.

We now have investigated whether protease inhibitors are modulated in the injured rat carotid artery and whether their expression may serve to alter the proteolytic balance at key time points during the formation of the neointima. In the present study, we examined two classes of inhibitors of PAs and MMPs and demonstrate that in these two classes of inhibitors only two specific protease inhibitors, PAI-1 and TIMP-2, are increased in injured arteries and that their location and time of expression in the vessel wall may help define their role in the response to injury.


*    Materials and Methods
up arrowTop
up arrowAbstract
up arrowIntroduction
*Materials and Methods
down arrowResults
down arrowDiscussion
down arrowReferences
 
Animals, Surgery, and Tissue Preparation
Three-month-old male Sprague-Dawley rats were obtained from Bantin & Kingman Inc, Seattle, Wash. Rats were anesthetized with 1.0 mL/kg of an intramuscular solution containing 1 mg/mL acepromazine (Fermenta Animal Health Corp), 50 mg/mL ketamine (Aveco Inc), and 5 mg/mL Rompun (Mobay Corp) in a saline solution. Balloon injury to the common carotid artery was performed by the passage of a 2F embolectomy catheter as previously described.9 Animals were killed with an overdose of pentobarbital. The arteries were flushed clear of blood with PBS, pH 7.4, removed, and stripped of the surrounding connective tissue and fatty material, leaving the adventitia. Samples intended for Northern analysis were immediately frozen in liquid nitrogen and stored at -70°C. Arteries that were to be examined immunohistochemically were perfusion-fixed in 10% neutral buffered formalin at physiological pressure for 5 minutes after being flushed with lactated Ringer's solution (Baxter). The carotid arteries were stored in formalin overnight before being embedded in paraffin. Rats were cared for according to the Principles of Laboratory Animal Care (formulated by the National Society for Medical Research) and the Guide for the Care and Use of Laboratory Animals (NIH publication No. 86-23, revised 1985.)

Immunohistochemistry
Histological sections (4 µm) were cut from paraffin-embedded rat carotid arteries, prepared, and placed on poly-L-lysine–coated microscope slides. The sections were deparaffinized by three changes in xylene for 5 minutes each. Slides were rehydrated in a graded alcohol series as follows: three changes of 100% ethanol for 5 minutes total, two changes of 95% ethanol for 4 minutes total, and one change of 75% ethanol for 1 minute. Slides were prepared for immunohistochemistry using the Vectastain Elite ABC kit (Vector Laboratories). Endogenous peroxidase activity was blocked by a 5-minute incubation in 3% hydrogen peroxide. Slides were washed in two changes of PBS, pH 7.2. Nonspecific binding of the secondary antibody was blocked by incubation in 10% normal goat serum for 10 minutes, followed by two changes of PBS. The rabbit anti-rat PAI-1 antibody (American Diagnostica) or control rabbit IgG (Vector Laboratories) was added at a concentration of 25 µg/mL in 1% BSA. PAI-1 antibody and control rabbit IgG were incubated overnight at 4°C. The primary antibody was washed in three changes of PBS for 1 minute each. Biotinylated anti-rabbit secondary antibody was added for 30 minutes. Slides were washed in three changes of PBS for 1 minute each, followed by avidin-biotin-alkaline phosphatase for 30 minutes. The slides were then washed in one change of PBS, followed by one wash in 0.05 mol/L Tris, pH 7.6, at 37°C for 5 minutes each. Slides were incubated at 37°C for 30 minutes in 175 mL 0.05 Tris with 4 mL DAB (132 mL of 0.05 mol/L Tris, pH 7.6, and 5 g DAB; aliquot stored at -70°C) and alkaline phosphatase substrate (Vector Laboratories), followed by one wash in distilled water for 1 minute. Slides were counterstained in hematoxylin, cleared in Histoclear (National Diagnostics), and mounted in Histomount (National Diagnostics). Immunohistochemical staining was visualized under bright-field illumination on a Leitz Dialux 20 EB and photographed using Ectachrome Elite 100 ASA.

Isolation of RNA and Northern Blot Analysis
Total cellular RNA was isolated from 12 rat common carotid arteries in pooled groups of four per time point by guanidinium isothiocyanate–phenol–chloroform extraction as previously described,10 except that tissue was first finely crushed under liquid nitrogen in a mortar and pestle and then homogenized for 30 seconds in a Brinkman PT10-35 homogenizer. Isolated RNA was resuspended in 0.5% SDS and quantified spectrophotometrically. RNA samples were separated in a 1% agarose/formaldehyde gel.11 RNA was transferred to Zeta-probe nylon membrane (Bio-Rad) as described by the manufacturer and cross-linked to the membrane using UV light (Stratagene). Filter hybridizations were carried out as described by Church and Gilbert.12 In general, hybridizations were performed in a solution of 1% BSA, 7% SDS, 0.5 mol/L sodium phosphate, pH 7.0, 1 mmol/L EDTA, and 20% formamide at 65°C. Filters were washed to a final stringency of 0.1x SSPE at 65°C (0.33 mol/L NaCl and 0.2 mol/L NaH2PO4, pH 7.4) and exposed to Kodak XAR x-ray film at -70°C using an intensifying screen and quantified on the PhosphorImager at the Markey Molecular Medicine Facility, Seattle, Wash.

Isolation of Arterial Protein and Western Analysis
Seven days after injury, carotid arteries were removed, and the intima, media, and adventitia were separated. The intima was separated by cutting open the artery longitudinally and then peeling out the intima with forceps. The media was separated from the adventitia by holding onto the media and pulling the adventitia; this process leaves some tightly connected adventitia remaining with the media. Tissue was then snap-frozen and processed as described for reverse zymography. Protein (10 µg per lane) was loaded and run on a 10% SDS-polyacrylamide gel and transferred to nitrocellulose. Rabbit anti–TIMP-2 antibody was added at 1:1000 for 30 minutes and visualized with 1:7500 dilution of anti-rabbit IgG (Fc)-alkaline phosphatase conjugate and subsequent color development (Promega).

Probes
The rat PAI-1 cDNA probe used in the present study was generously provided by Dr T. Gelehrter.13 The TIMP-2 cDNA and TIMP-2 antibody were provided by Dr Keith Langley (Amgen, Thousand Oaks, Calif). For Northern hybridizations, plasmids were radiolabeled by the nick-translation method14 using the large fragment of Klenow DNA polymerase and [32P]dCTP (3000 Ci/mmol).

Reverse Zymography
Carotid arteries were removed, stored, and homogenized in 0.05 mol/L Tris, 0.01 mol/L CaCl2, 2.0 mol/L guanidine HCl, and 0.2% Triton X-100, pH 7.5, as described by Dean et al.15 Homogenate was centrifuged at 10 000g for 1 minute, and the supernatant was dialyzed against 3 vol of 0.05 mol/L Tris-HCl, pH 7.5, and 0.2% Triton X-100 over 2 days (SpectraPore, Spectrum). Aliquots were frozen at -70°C. Protein concentration was determined by the BCA assay (Pierce) as described by the manufacturer. For PAI analysis, 20-µg samples were run on a 10% SDS-PAGE as described by Laemmli16 and then washed for 10 minutes in 2.5% Triton X-100 (Sigma Chemical Co) and 10 minutes in PBS. The gel was overlaid onto a 1.25% agar (Difco) containing 40 µg/mL plasminogen (American Diagnostica), 250 mU/mL human recombinant HMW urokinase (Calbiochem), and 2% nonfat dry milk powder (wt/vol) (Carnation) in 0.1 mol/L Tris, pH 8.1. The reverse zymogram was developed at 4°C overnight and then at 37°C for 3 to 6 hours. Visualization was by dark-field illumination. For TIMP reverse zymography, 100 µg of protein was run on a 10% SDS-polyacrylamide gel containing 1 mg/mL gelatin and 1 mL of MMP solution (University Technologies Intl Inc). The gel was washed in 2.5% Triton X-100 and developed for 22 hours at 37°C before staining with Coomassie blue.

Statistics
PhosphorImager data from Northern blots were normalized to the signal from 28S rRNA labeling, as a measure of loading, and expressed as fold increase compared with uninjured carotid arteries. The mean increase is reported with two-tailed 95% confidence intervals by one-way ANOVA compared with the 0-hour injured control vessel. Error bars are standard deviations of the mean.


*    Results
up arrowTop
up arrowAbstract
up arrowIntroduction
up arrowMaterials and Methods
*Results
down arrowDiscussion
down arrowReferences
 
Effects of Arterial Injury on PAI Expression
To establish whether inhibitors of PA activity were present in the injured vessel wall, extracts of injured rat carotid arteries were analyzed by reverse zymography. Reverse zymography provides a qualitative measure of inhibitors of PA activity, including inactive PAI-1, which is activated by denaturants in the polyacrylamide gel. After injury, the only detectable inhibitor of PA activity was PAI-1 (50 kD). PAI-2 was not detectable. Six hours after injury, PAI-1 reached maximal levels (Fig 1Down). This activity decreased by 24 hours, after which it was undetectable in this assay.



View larger version (34K):
[in this window]
[in a new window]
 
Figure 1. Reverse zymogram demonstrating PAI-1 activity in balloon-injured rat common carotid artery. PAI-1 activity peaked 6 hours after injury and returned to undetectable baseline levels by 3 days. Five carotid arteries were used per time point, and visualization was by dark-field illumination of an unstained gel, where undigested casein appears gray on a black background.

Northern Analysis of PAI-1 mRNA
To determine the kinetics of PAI-1 induction in the rat carotid, total mRNA from the carotids of balloon-injured rats was analyzed on Northern blots using 32P-labeled cDNA probes specific for rat PAI-1. Rat PAI-1 mRNA has only one transcript, whereas PAI-1 in many other species has 3.2- and 2.3-kb transcripts.13 17 PAI-1 mRNA was induced by injury in the rat common carotid as shown in Fig 2Down. This induction was transient and returned to baseline levels by 3 days after injury. The induction of message was maximal at 6 hours (18-fold increase; n=3; SD, 10.6; two-tailed 95% confidence interval, -7 to 45). Although the mRNA levels were increased on three independent blots, the increase was not statistically different from that for the control 0-hour injured carotid artery. This induction was dramatically decreased by 24 hours and returned to baseline levels by day 3 after injury.



View larger version (38K):
[in this window]
[in a new window]
 
Figure 2. A, Northern analysis of PAI-1 mRNA in rat carotid artery after balloon injury. Four arteries were extracted per time point. B, PAI-1 signal normalized to 28S rRNA and reported as fold change compared with uninjured carotid arteries. Graph represents the mean±SD of independent pools of carotid arteries (four arteries per pool, n=3).

Immunohistochemical Analysis of PAI-1 Antigen in Injured Rat Carotid Arteries
To determine the cell type responsible for the increase in PAI-1 expression, cross sections of injured carotid arteries were stained for PAI-1. PAI-1 expression was increased in a subpopulation of cells in the media at 6 hours after injury (Fig 3BDown). PAI-1 staining was not seen by 3 days (Fig 3CDown). PAI-1 was absent in the 15-minute injured vessel and in the normal uninjured vessel. Adventitial staining was present in the IgG controls (Fig 3DDown, 3EDown, and 3FDown). Adventitial staining was also present in sections stained with anti–PAI-1 preincubated with human PAI-1 antigen (data not shown). Taken together, these data from Northern blotting, reverse zymography, and immunohistochemistry clearly demonstrate that medial SMCs increase transiently the expression of PAI-1 in response to injury.



View larger version (147K):
[in this window]
[in a new window]
 
Figure 3. A through C, Immunohistochemistry of PAI-1 15 minutes after injury (A), 6 hours after injury (B; PAI-1 has reached maximal levels), and 3 days after injury (C; PAI-1 has returned to control levels). D through F, Immunohistochemistry for control rabbit IgG 15 minutes after injury (D), 6 hours after injury (E), and 3 days after injury (F). I indicates intima; M, media; A, adventitia; and arrow, external elastic lamina.

Effect of Arterial Injury on Inhibitors of MMPs
The carotid artery extracts were also analyzed for inhibitors of MMPs. TIMP-2 (18 kD) was the only MMP inhibitor detected by reverse zymography and appeared to be modulated by injury (Fig 4Down). TIMP-1 (Mr, 28 kD) activity was not detectable in the carotid extracts (Fig 4Down). Immediately after injury through 24 hours, TIMP-2 was present at low levels. Three days after injury, TIMP-2 inhibitory activity increased and reached maximal activity around day 5. By 14 days after injury, TIMP-2 was decreased.



View larger version (32K):
[in this window]
[in a new window]
 
Figure 4. Reverse zymogram demonstrating changes in the activity of TIMP-2 protein in the injured rat common carotid artery. Five arteries were extracted per time, and 100 µg protein was loaded per lane. Dark bands are undigested gelatin stained with Coomassie blue, representing areas of MMP inhibition.

Northern Analysis of TIMP-2 mRNA After Arterial Injury
TIMP-2 levels began to increase 24 hours after balloon injury and reached a maximal 3-fold induction at day 7 (n=3; SD, 0.65; two-tailed 95% confidence interval, 1.4 to 4.7) (Fig 5Down). TIMP-2 mRNA was not significantly elevated at 2 weeks. Rat TIMP-2 has two transcripts, 1.0 and 3.5 kb. In response to injury, only the 1.0-kb transcript was significantly induced, whereas the 3.5-kb transcript was not modulated and remained constitutively expressed.



View larger version (38K):
[in this window]
[in a new window]
 
Figure 5. A, Northern blot analysis shows changes in TIMP-2 mRNA levels in the rat common carotid artery after injury. Total RNA was isolated from injured carotid arteries (four arteries per time point) at the times indicated above. B, The 1.0-kb mRNA TIMP-2 signal was normalized to 28S ribosomal RNA, and the values at each time point after injury were reported as fold change compared with uninjured carotid arteries (uninjured, 7-day, and 14-day values are mean±SD of three pools of carotid arteries [four arteries per pool]). *95% confidence interval (1.4 to 4.7) compared with uninjured carotid artery. The 3.5-kb mRNA was not modulated by injury.

Western Analysis of TIMP-2 Antigen in the Injured Carotid Artery
The location of TIMP-2 after injury was determined by physically separating the intima, media, and adventitia. Protein from each region was then extracted and analyzed by Western blotting for TIMP-2 antigen (Fig 6Down). Seven days after injury, TIMP-2 antigen was confined to the intima and was not detected in the media or the adventitia. The data from Northern blotting, reverse zymography, and Western blotting clearly demonstrate that TIMP-2 is induced by balloon injury in the rat carotid artery and that TIMP-2 expression is limited to the intima at day 7 after injury.



View larger version (71K):
[in this window]
[in a new window]
 
Figure 6. Western analysis of TIMP-2 antigen in various vascular wall compartments 7 days after injury. Lanes are as follows: C, recombinant TIMP-2 as positive control; 1, intima; 2, media; and 3, adventitia.


*    Discussion
up arrowTop
up arrowAbstract
up arrowIntroduction
up arrowMaterials and Methods
up arrowResults
*Discussion
down arrowReferences
 
Previous investigators have suggested that changes in protease activity are required for cell migration following arterial injury.2 3 4 5 The question addressed by the present study is whether protease inhibitors are regulated by balloon injury in the rat carotid artery. The main findings of the present study are that members of the serine protease inhibitor (serpin) and MMP inhibitor families are increased after balloon catheter injury in the rat carotid artery. We show that two members of these protease inhibitor families, PAI-1 and TIMP-2, are increased and that the expression of these inhibitors follows different spatial and temporal profiles. Other PAIs and TIMPs were not detected.

PAI-1 mRNA, antigen, and activity were induced rapidly after injury, reached a maximum by 6 hours, and then quickly returned to baseline after 24 hours. TIMP-2 was induced at 1 day, reached maximal levels in the intima around day 7, and remained elevated through 2 weeks. TIMP-2 might be complexed at late time points with proteases (eg, MMP-2). This possibility might explain the apparent decline in TIMP-2 activity despite the presence of TIMP-2 mRNA at 14 days. The increase in protease inhibitors, in conjunction with previous observations of regulated protease activity, suggests that changes in proteolytic and fibrinolytic activity may be central events in the response to injury.

There is strong experimental evidence both in vivo and in vitro that regulation of matrix proteolysis is important for tumor invasion, tissue remodeling, angiogenesis, and development. Changes in the proteolytic balance between protease and anti-protease expression have been associated with diseases such as atherosclerosis,18 19 metastasis,20 and thromboembolism.21 Proteinases and their inhibitors also play an important role in tissue remodeling,22 23 wound repair,24 and many other normal processes related to reproduction, such as lactation,25 uterine implantation,26 and gestation.27 All of these events require controlled expression of PAs or MMPs or both in conjunction with their respective inhibitors. Vascular repair in response to injury might also require a highly controlled pattern of protease and anti-protease expression by vascular SMCs. Vascular SMCs degrade ECM by plasminogen-dependent and plasminogen-independent pathways.28 Plasmin and the MMPs form an interactive proteolytic cascade, since they affect the activation of one another. This proteolytic cascade is able to degrade most of the ECM components, including collagen types I, III, and IV, laminin, fibronectin, elastin, and proteoglycans. A shift in the balance between the proteases and their respective inhibitors is probably necessary for vascular remodeling to occur.

PAI-1 Expression After Arterial Injury
PAI-1 is a single-chain polypeptide with an Mr of 50 kD that inhibits urokinase PA as well as single- and two-chain forms of tissue PA by rapidly forming a 1:1 stoichiometric complex. PAI-1 is an early growth response gene in fibroblasts and hepatocytes and is induced during the transition from the quiescent state (G0) to the G1 phase of the cell cycle.29 In the mouse, the highest concentrations of PAI-1 are found in the aorta, consistent with observations that PAI-1 is a major product of smooth muscle cells.30 The 18-fold increase in expression of PAI-1 at 6 hours after injury is consistent with the time course of PAI-1 induction seen by other investigators using cytokines31 or with other forms of injury.29 PAI-1 is found in both active and latent forms. Northern analysis, reverse zymography, and immunohistochemistry do not distinguish between the two forms. This limits our ability to determine whether PAI-1 is having a physiological effect after injury. However, PAI-1 as measured in the present study might be biologically active, because it can be stabilized in the vessel wall through association with serum-derived vitronectin.32

Plasma PAI-1 increases after trauma and inflammation as one of several APR proteins.33 PAI-1 is synthesized by a wide variety of tissues in vivo, unlike most APR proteins, which are synthesized in the liver.30 In the rat, PAI-1 is a tissue-associated inhibitor of fibrinolysis at sites of vascular disruption and inflammation. Balloon catheter injury inflicts extensive damage on the vessel wall. The immediate priority of the vessel after this type of extensive injury is to prevent hemorrhage. Control of vascular disruption and hemorrhage is achieved through the formation of thrombi. At early times after arterial injury, there is platelet adherence and limited fibrin deposition on the luminal surface, but the luminal surface clears after 1 day. An early increase in tissue-associated PAI-1 may serve to limit fibrinolysis during this early repair period. Additionally, PAs are expressed in the injured rat carotid artery and are necessary but not sufficient for SMC migration. Tranexamic acid, a synthetic PAI, blocks SMC migration.3 PAI-1 may have a similar effect by limiting proteolytic activity at early time points after injury and as a result block migration.

TIMP-2 and Arterial Injury
MMPs, as well as PAs, are induced in rat injured carotid arteries.4 5 A 92-kD collagenolytic activity thought to be MMP-9 is increased 24 hours after injury and then decreases to baseline levels. Gelatinase (72 kD) is expressed constitutively, and its activated form is increased 5 days after injury and decreases after 14 days.4 5 A low-molecular-weight MMP (24.5 kD) with broad proteolytic activity and high elastinolytic activity is found in the adventitia and is increased 5 days after injury. This 24.5-kD MMP may be involved in elastin turnover in the adventitia. This increased activity of MMPs coincides with increased TIMP-2 expression. Increased protease inhibitors could block cell migration from the media. This theory is supported by experiments in which a synthetic MMP inhibitor, GM 6001, is able to block 97% of the SMCs migrating into the intima by blocking MMP activity.5

TIMP-2 is a nonglycosylated 21-kD protein that selectively forms a 1:1 complex with the latent and activated form of 72-kD type IV collagenase. TIMP-2 preferentially binds to the 72-kD proenzyme, whereas TIMP-1 preferentially binds to the 92-kD proenzyme form of type IV collagenase. Therefore, increased TIMP-2 expression may specifically limit the activity of 72-kD type IV collagenase. Although TIMP-1 and TIMP-2 have preferential binding patterns, they are able to inhibit all members of the MMP subclasses that have been tested.34 The preference of inhibitors for specific types and forms of MMPs confers an added level of control for proteolytic degradation.

There are two TIMP-2 transcripts expressed by SMCs. The 3.5-kb transcript of TIMP-2 is constitutively expressed after injury, whereas the 1.0-kb transcript is increased 3-fold. The two transcripts are thought to arise from alternative splicing of 5'-untranslated regions.35 Both transcripts have been shown to encode identical proteins.36 37 The opposite pattern of differential regulation of the TIMP-2 message has been described in vitro by Testa,38 who reported that the 3.5-kb transcript was modulated and the 1.0-kb transcript was minimally induced. Khokha et al39 have shown that even a 29% increase in TIMP-1 mRNA expression has a significant effect on the invasive phenotype. These results support the conclusion that the increase in TIMP-2 mRNA and activity seen in the present study is likely to produce a strong biological effect in the vessel wall and may serve to limit migration.

We have also examined TIMP-1 and TIMP-3 mRNA expression in the rat carotid artery after balloon injury and found no significant modulation of TIMP-1 and no detectable TIMP-3 expression (data not shown). These findings indicate that TIMP-1 and TIMP-2 are not regulated in parallel, a conclusion reached by other investigators.35 TIMP-1 is present at lower levels in rat arteries than in baboon arteries.40 This observation may suggest that different species preferentially use different proteases and their respective inhibitors to perform similar functions.

In summary, we have demonstrated that two endogenous inhibitors of protease activity, PAI-1 and TIMP-2, are increased in response to arterial injury in the rat carotid artery. Taken together with our previous observations on the induction of proteases during SMC migration, these results support our conclusion that changes in proteolytic activity are necessary for SMC migration and may be a critical part of the response to injury in the carotid artery.


*    Selected Abbreviations and Acronyms
 
APR protein = acute phase–reactant protein
DAB = diaminobenzidine tetrahydrochloride
ECM = extracellular matrix
MMP = matrix metalloproteinase
PA = plasminogen activator
PAI = PA inhibitor
SMC = smooth muscle cell
TIMP = tissue inhibitor of MMPs


*    Acknowledgments
 
This study was supported by National Institutes of Health grants HL-18645 and HL-52459 and training grant T32 HL-07312 (Dr Hasenstab). We are grateful to Dr Keith E. Langley, Amgen Inc, Thousand Oaks, Calif, for the TIMP-2 cDNA and antibody, Dr Thomas D. Gelehrter for the PAI-1 cDNA, and Holly Lea, University of Washington, for excellent surgical work.


*    Footnotes
 
Reprint requests to David Hasenstab, University of Washington, Department of Surgery, 356410, Seattle, WA 98195.

Received December 13, 1995; accepted December 19, 1996.


*    References
up arrowTop
up arrowAbstract
up arrowIntroduction
up arrowMaterials and Methods
up arrowResults
up arrowDiscussion
*References
 

  1. Ross R. The pathogenesis of atherosclerosis: a perspective for the 1990's. Nature. 1993;362:801-809. [Medline] [Order article via Infotrieve]
  2. Clowes AW, Clowes MM, Kirkman TR, Jackson CL, Au YPT, Kenagy R. Heparin inhibits the expression of tissue-type plasminogen activator by smooth muscle cells in injured rat carotid artery. Circ Res. 1992;70:1128-1136. [Abstract/Free Full Text]
  3. Jackson CL, Reidy MA. The role of plasminogen activation in smooth muscle migration after arterial injury. Ann N Y Acad Sci. 1992;667:141-150. [Abstract]
  4. Zempo N, Kenagy RD, Au YPT, Bendeck M, Clowes MM, Reidy MA, Clowes AW. Matrix metalloproteinases of vascular wall cells are increased in balloon-injured rat carotid artery. J Vasc Surg. 1994;20:209-217. [Medline] [Order article via Infotrieve]
  5. Bendeck MP, Zempo N, Clowes AW, Galardy RE, Reidy MA. Smooth muscle cell migration and matrix metalloproteinase expression after arterial injury in the rat. Circ Res. 1994;75:539-545. [Abstract/Free Full Text]
  6. Pauly RR, Passaniti A, Bilato C, Monticone R, Cheng L, Papadopoulos N, Gluzband YA, Smith L, Weinstein C, Lakatta EG, Crow MT. Migration of cultured vascular smooth muscle cells through a basement membrane barrier requires type IV collagenase activity and is inhibited by cellular differentiation. Circ Res. 1994;75:41-54. [Abstract/Free Full Text]
  7. Moscatelli D, Rifkin DB. Membrane and matrix localization of proteinases: a common theme in tumor cell invasion and angiogenesis. Biochim Biophys Acta. 1988;948:67-85. [Medline] [Order article via Infotrieve]
  8. Stettler-Stevenson WG, Liotta LA, Kleiner DE. Extracellular matrix 6: role of matrix metalloproteinases in tumor invasion and metastasis. FASEB J. 1993;7:1434-1441. [Abstract]
  9. Clowes AW, Reidy MA, Clowes MM. Kinetics of cellular proliferation after arterial injury. Lab Invest. 1983;49:327-333. [Medline] [Order article via Infotrieve]
  10. Chomczynski P, Sacchi N. Single-step method of RNA isolation by acid guanidinium thiocyanate-phenol-chloroform extraction. Anal Biochem. 1986;162:156-159.
  11. Sambrook J, Fritsch EF, Maniatis T. Molecular Cloning: A Laboratory Manual. 2nd ed. Cold Spring Harbor, NY: Cold Spring Harbor Laboratory Press; 1989:7.43.
  12. Church GM, Gilbert W. Genomic sequencing. Proc Natl Acad Sci U S A. 1984;81:1991-1995. [Abstract/Free Full Text]
  13. Zeheb R, Gelehrter TD. Cloning and sequencing of cDNA for the rat plasminogen activator inhibitor-1. Gene. 1988;73:459-468. [Medline] [Order article via Infotrieve]
  14. Sambrook J, Fritsch EF, Maniatis T. Molecular Cloning: A Laboratory Manual. 2nd ed. Cold Spring Harbor, NY: Cold Spring Harbor Laboratory Press; 1989:10.6.
  15. Dean DD, Schwartz Z, Muniz OE, Gomez R, Swain LD, Howell DS, Boyan BD. Matrix vesicles are enriched in metalloproteinases that degrade proteoglycans. Calcif Tissue Int. 1992;50:342-349. [Medline] [Order article via Infotrieve]
  16. Laemmli UK. Cleavage of structural proteins during the assembly of the head bacteriophage T4. Nature. 1970;227:680-685. [Medline] [Order article via Infotrieve]
  17. Ginsburg D, Zeheb R, Yang AY, Rafferty UM, Andreasen PA, Nielsen L, Dano K, Lebo RV, Gelehrter TD. cDNA cloning of human plasminogen activator-inhibitor from endothelial cells. J Clin Invest. 1986;78:1673-1680.
  18. Schneiderman JA, Sawdey MS, Keeton MR, Bordin GM, Bernstein EF, Dilley RB, Loskutoff DJ. Increased type 1 plasminogen activator inhibitor gene expression in atherosclerotic human arteries. Proc Natl Acad Sci U S A. 1992;89:6998-7002. [Abstract/Free Full Text]
  19. Lupu F, Bergonzelli GE, Heim DA, Cousin E, Genton CY, Bachmann F, Kruithof EKO. Localization and production of plasminogen activator inhibitor-1 in human healthy and atherosclerotic arteries. Arterioscler Thromb. 1993;13;1090-1100.
  20. Liotta LA, Steeg PS, Stettler-Stevenson WG. Cancer metastasis and angiogenesis: an imbalance of positive and negative regulation. Cell. 1991;64:327-336. [Medline] [Order article via Infotrieve]
  21. Lang IM, Marsh JJ, Olman MA, Moser KM, Loskutoff DJ, Schleef RR. Expression of type 1 plasminogen activator inhibitor in chronic pulmonary thromboemboli. Circulation. 1994;89:2715-2721. [Abstract/Free Full Text]
  22. Woessner JF. Matrix metalloproteinases and their inhibitors in connective tissue remodeling. FASEB J. 1991;5:2145-2154. [Abstract]
  23. Overall CM. Regulation of tissue inhibitor of matrix metalloproteinase expression. Ann N Y Acad Sci. 1994;732:51-64. [Medline] [Order article via Infotrieve]
  24. Salo T, Makela M, Kylmanieme M, Autio-Harmainen H, Larjava H. Expression of matrix metalloproteinase-2 and -9 during early human wound healing. Lab Invest. 1994;70:176-182. [Medline] [Order article via Infotrieve]
  25. Talhouk RS, Bissell MJ, Werb Z. Coordinated expression of extracellular matrix-degrading proteinases and their inhibitors regulates mammary epithelial function during involution. J Cell Biol. 1992;118:1271-1282. [Abstract/Free Full Text]
  26. Lala PK, Graham CH. Mechanisms of trophoblast invasiveness and their control: the role of proteases and protease inhibitors. Cancer Metastasis Rev. 1990;9:369-379. [Medline] [Order article via Infotrieve]
  27. Brenner CA, Adler RR, Rappolee DA, Pederson RA, Werb Z. Genes for extracellular matrix-degrading metalloproteinases and their inhibitor, TIMP, are expressed during early mammalian development. Genes Dev. 1989;3:848-859. [Abstract/Free Full Text]
  28. Sperti G, van Leeuwen RTJ, Quax PHA, Maseri A, Kluft C. Cultured rat aortic vascular smooth muscle cells digest naturally produced extracellular matrix: involvement of plasminogen-dependent and plasminogen-independent pathways. Circ Res. 1992;71:385-392. [Abstract/Free Full Text]
  29. Thornton AJ, Bruzdzinski CJ, Raper SE, Gelehrter TD. Plasminogen activator inhibitor-1 is an immediate early response gene in regenerating rat liver. Cancer Res. 1994;54:1337-1343. [Abstract/Free Full Text]
  30. Sawdey MS, Loskutoff DJ. Regulation of murine type 1 plasminogen activator inhibitor gene expression in vivo. J Clin Invest. 1991;88:1346-1353.
  31. Reilly CF, McFall RC. Platelet derived growth factor and transforming growth factor-beta regulate plasminogen activator inhibitor-1 synthesis in vascular smooth muscle cells. J Biol Chem. 1991;266:9419-9427. [Abstract/Free Full Text]
  32. Seiffert D, Mimuro J, Schleef RR, Loskutoff DJ. Interactions between type 1 plasminogen activator inhibitor, extracellular matrix and vitronectin. Cell Differ Dev. 1990;32:287-292. [Medline] [Order article via Infotrieve]
  33. Prins MH, Hirsh J. A critical review of the evidence supporting a relationship between impaired fibrinolytic activity and venous thromboembolism. Arch Intern Med. 1991;151:1721-1731. [Abstract]
  34. Mc Donnell S, Matrisian LM. Stromelysin in tumor progression and metastasis. Cancer Metastasis Rev. 1990;9:305-319. [Medline] [Order article via Infotrieve]
  35. Stettler-Stevenson WG, Brown PD, Onisto M, Levy AT, Liotta LA. Tissue inhibitor of metalloproteinases-2 (TIMP-2) mRNA expression in tumor cell lines and human tumor tissues. J Biol Chem. 1990;265:13933-13938. [Abstract/Free Full Text]
  36. Shimizu S, Malik K, Sejima H, Kishi J, Hayakawa T, Koiwai O. Cloning and sequencing of the cDNA encoding a mouse tissue inhibitor of metalloproteinase-2. Gene. 1992;114:291-292. [Medline] [Order article via Infotrieve]
  37. Leco KJ, Hayden LJ, Sharma RR, Rocheleau H, Greenberg AH, Edwards DR. Differential regulation of TIMP-1 and TIMP-2 mRNA expression in normal and Ha-ras-transformed murine fibroblasts. Gene. 1992;117:209-217. [Medline] [Order article via Infotrieve]
  38. Testa JE. Loss of the metastatic phenotype by a human epidermoid carcinoma cell line, HEp-3, is accompanied by increased expression of tissue inhibitor of metalloproteinase 2. Cancer Res. 1992;52:5597-5603. [Abstract/Free Full Text]
  39. Khokha R, Waterhouse P, Yagel S, Lala PK, Overall CM, Norton G, Denhardt DT. Antisense RNA-induced reduction in murine TIMP levels confers oncogenicity on Swiss 3T3 cells. Science. 1989;243:947-950. [Abstract/Free Full Text]
  40. Forough R, Hasenstab D, Koyama N, Lea H, Clowes M, Clowes AW. Generating antibodies against secreted proteins using vascular smooth muscle cells transduced with replication-defective retrovirus. Biotechniques. 1996;20:694-701.[Medline] [Order article via Infotrieve]



This article has been cited by other articles:


Home page
NeurologyHome page
R. J. Osborne, S. Welle, S. L. Venance, C. A. Thornton, and R. Tawil
Expression profile of FSHD supports a link between retinal vasculopathy and muscular dystrophy
Neurology, February 20, 2007; 68(8): 569 - 577.
[Abstract] [Full Text] [PDF]


Home page
Arterioscler. Thromb. Vasc. Bio.Home page
J. Sainz and M. Sata
Maintenance of Vascular Homeostasis by Bone Marrow-Derived Cells.
Arterioscler. Thromb. Vasc. Biol., June 1, 2006; 26(6): 1196 - 1197.
[Full Text] [PDF]


Home page
Cardiovasc ResHome page
A. C. Newby
Matrix metalloproteinases regulate migration, proliferation, and death of vascular smooth muscle cells by degrading matrix and non-matrix substrates
Cardiovasc Res, February 15, 2006; 69(3): 614 - 624.
[Abstract] [Full Text] [PDF]


Home page
J Am Coll CardiolHome page
G. Xiang, M. D. Schuster, T. Seki, P. Witkowski, S. Eshghi, and S. Itescu
Downregulated Expression of Plasminogen Activator Inhibitor-1 Augments Myocardial Neovascularization and Reduces Cardiomyocyte Apoptosis After Acute Myocardial Infarction
J. Am. Coll. Cardiol., August 2, 2005; 46(3): 536 - 541.
[Abstract] [Full Text] [PDF]


Home page
Physiol. Rev.Home page
A. C. Newby
Dual Role of Matrix Metalloproteinases (Matrixins) in Intimal Thickening and Atherosclerotic Plaque Rupture
Physiol Rev, January 1, 2005; 85(1): 1 - 31.
[Abstract] [Full Text] [PDF]


Home page
J. Exp. Med.Home page
G. Xiang, M. D. Schuster, T. Seki, A. A. Kocher, S. Eshghi, A. Boyle, and S. Itescu
Down-regulation of Plasminogen Activator Inhibitor 1 Expression Promotes Myocardial Neovascularization by Bone Marrow Progenitors
J. Exp. Med., December 20, 2004; 200(12): 1657 - 1666.
[Abstract] [Full Text] [PDF]


Home page
Cardiovasc ResHome page
X. W. Cheng, M. Kuzuya, T. Sasaki, S. Kanda, N. Tamaya-Mori, T. Koike, K. Maeda, E. Nishitani, and A. Iguchi
Green tea catechins inhibit neointimal hyperplasia in a rat carotid arterial injury model by TIMP-2 overexpression
Cardiovasc Res, June 1, 2004; 62(3): 594 - 602.
[Abstract] [Full Text] [PDF]


Home page
BloodHome page
H.-C. Chen and E. P. Feener
MEK1,2 response element mediates angiotensin II--stimulated plasminogen activator inhibitor-1 promoter activation
Blood, April 1, 2004; 103(7): 2636 - 2644.
[Abstract] [Full Text] [PDF]


Home page
Arterioscler. Thromb. Vasc. Bio.Home page
K. Kallenbach, H. A. Fernandez, G. Seghezzi, F. G. Baumann, S. Patel, E. A. Grossi, A. C. Galloway, and P. Mignatti
A Quantitative In Vitro Model of Smooth Muscle Cell Migration Through the Arterial Wall Using the Human Amniotic Membrane
Arterioscler. Thromb. Vasc. Biol., June 1, 2003; 23(6): 1008 - 1013.
[Abstract] [Full Text] [PDF]


Home page
J. Biol. Chem.Home page
E. Dai, H. Guan, L. Liu, S. Little, G. McFadden, S. Vaziri, H. Cao, I. A. Ivanova, L. Bocksch, and A. Lucas
Serp-1, a Viral Anti-inflammatory Serpin, Regulates Cellular Serine Proteinase and Serpin Responses to Vascular Injury
J. Biol. Chem., May 9, 2003; 278(20): 18563 - 18572.
[Abstract] [Full Text] [PDF]


Home page
Circ. Res.Home page
M. B. Taubman
Angiotensin II: A Vasoactive Hormone With Ever-Increasing Biological Roles
Circ. Res., January 10, 2003; 92(1): 9 - 11.
[Full Text] [PDF]


Home page
Arterioscler. Thromb. Vasc. Bio.Home page
S. Tanaka, H. Koyama, T. Ichii, A. Shioi, M. Hosoi, E. W. Raines, and Y. Nishizawa
Fibrillar Collagen Regulation of Plasminogen Activator Inhibitor-1 Is Involved in Altered Smooth Muscle Cell Migration
Arterioscler. Thromb. Vasc. Biol., October 1, 2002; 22(10): 1573 - 1578.
[Abstract] [Full Text] [PDF]


Home page
J. Biol. Chem.Home page
A. I. Vulin and F. M. Stanley
A Forkhead/Winged Helix-related Transcription Factor Mediates Insulin-increased Plasminogen Activator Inhibitor-1 Gene Transcription
J. Biol. Chem., May 31, 2002; 277(23): 20169 - 20176.
[Abstract] [Full Text] [PDF]


Home page
Circ. Res.Home page
S. Sartore, A. Chiavegato, E. Faggin, R. Franch, M. Puato, S. Ausoni, and P. Pauletto
Contribution of Adventitial Fibroblasts to Neointima Formation and Vascular Remodeling: From Innocent Bystander to Active Participant
Circ. Res., December 7, 2001; 89(12): 1111 - 1121.
[Abstract] [Full Text] [PDF]


Home page
CirculationHome page
M. B. DeYoung, C. Tom, and D. A. Dichek
Plasminogen Activator Inhibitor Type 1 Increases Neointima Formation in Balloon-Injured Rat Carotid Arteries
Circulation, October 16, 2001; 104(16): 1972 - 1971.
[Abstract] [Full Text] [PDF]


Home page
Arterioscler. Thromb. Vasc. Bio.Home page
J. L. Johnson, G. J. J. M. van Eys, G. D. Angelini, and S. J. George
Injury Induces Dedifferentiation of Smooth Muscle Cells and Increased Matrix-Degrading Metalloproteinase Activity in Human Saphenous Vein
Arterioscler. Thromb. Vasc. Biol., July 1, 2001; 21(7): 1146 - 1151.
[Abstract] [Full Text] [PDF]


Home page
Am. J. Physiol. Renal Physiol.Home page
J. Chen, S. Brodsky, H. Li, D. J. Hampel, T. Miyata, T. Weinstein, U. Gafter, J. T. Norman, L. G. Fine, and M. S. Goligorsky
Delayed branching of endothelial capillary-like cords in glycated collagen I is mediated by early induction of PAI-1
Am J Physiol Renal Physiol, July 1, 2001; 281(1): F71 - F80.
[Abstract] [Full Text] [PDF]


Home page
CirculationHome page
S. Konstantinides, K. Schafer, T. Thinnes, and D. J. Loskutoff
Plasminogen Activator Inhibitor-1 and Its Cofactor Vitronectin Stabilize Arterial Thrombi After Vascular Injury in Mice
Circulation, January 30, 2001; 103(4): 576 - 583.
[Abstract] [Full Text] [PDF]


Home page
Arterioscler. Thromb. Vasc. Bio.Home page
D. Hasenstab, H. Lea, and A. W. Clowes
Local Plasminogen Activator Inhibitor Type 1 Overexpression in Rat Carotid Artery Enhances Thrombosis and Endothelial Regeneration While Inhibiting Intimal Thickening
Arterioscler. Thromb. Vasc. Biol., March 1, 2000; 20(3): 853 - 859.
[Abstract] [Full Text] [PDF]


Home page
CirculationHome page
B. H. Strauss, H. K. Lau, K. A. Bowman, J. Sparkes, R. J. Chisholm, M. B. Garvey, L. L. Fenkell, M. K. Natarajan, I. Singh, and J. M. Teitel
Plasma Urokinase Antigen and Plasminogen Activator Inhibitor-1 Antigen Levels Predict Angiographic Coronary Restenosis
Circulation, October 12, 1999; 100(15): 1616 - 1622.
[Abstract] [Full Text] [PDF]


Home page
Cardiovasc ResHome page
H. K.F. Lau
Regulation of proteolytic enzymes and inhibitors in two smooth muscle cell phenotypes
Cardiovasc Res, September 1, 1999; 43(4): 1049 - 1059.
[Abstract] [Full Text] [PDF]


Home page
Arterioscler. Thromb. Vasc. Bio.