Donate Help Contact The AHA Sign In Home
American Heart Association
Arteriosclerosis, Thrombosis, and Vascular Biology
Search: search_blue_button Advanced Search
Arteriosclerosis, Thrombosis, and Vascular Biology. 2006;26:773-779
Published online before print January 12, 2006, doi: 10.1161/01.ATV.0000203510.96492.14
This Article
Right arrow Abstract Freely available
Right arrow Full Text (PDF)
Right arrow Data Supplement
Right arrow All Versions of this Article:
26/4/773    most recent
01.ATV.0000203510.96492.14v1
Right arrow Alert me when this article is cited
Right arrow Alert me if a correction is posted
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 Google Scholar
Google Scholar
Right arrow Articles by Waeckel, L.
Right arrow Articles by Silvestre, J.-S.
Right arrow Search for Related Content
PubMed
Right arrow PubMed Citation
Right arrow Articles by Waeckel, L.
Right arrow Articles by Silvestre, J.-S.
(Arteriosclerosis, Thrombosis, and Vascular Biology. 2006;26:773.)
© 2006 American Heart Association, Inc.


Vascular Biology

Tetrapeptide AcSDKP Induces Postischemic Neovascularization Through Monocyte Chemoattractant Protein-1 Signaling

Ludovic Waeckel; Jérôme Bignon; Jian-Miao Liu; Delphine Markovits; Téni G. Ebrahimian; José Vilar; Barend Mees; Olivier Blanc-Brude; Véronique Barateau; Sophie Le ricousse-Roussanne; Micheline Duriez; Gérard Tobelem; Joanna Wdzieczak-Bakala; Bernard I Lévy; Jean-Sébastien Silvestre

From the Cardiovascular Research Center (L.W., T.G.E., J.V., O.B.-B., M.D., B.I.L., J.-S.S.), INSERM U689, Université Paris 7, Paris, France; UPR 2301 CNRS (J.B., J.-M.L., D.M., J.W.-B.), Gif-sur-Yvette, France; Institut des Vaisseaux et du Sang (V.B., S.L.-R., G.T.), Hôpital Lariboisière, Paris, France; and the Department of Vascular Surgery (B.M.), Department.of Cell Biology & Genetics Erasmus University Medical Center Rotterdam, the Netherlands.

Correspondence to Jean-Sebastien Silvestre, U689 INSERM, Hôpital Lariboisière, 41 Bd de la Chapelle, 75475 Paris cedex 10, France. E-mail Jean-Sebastien.Silvestre{at}larib.inserm.fr


*    Abstract
up arrowTop
*Abstract
down arrowIntroduction
down arrowMaterials and Methods
down arrowResults
down arrowDiscussion
down arrowReferences
 
Background— We investigated the putative proangiogenic activity and molecular pathway(s) of the tetrapeptide acetyl-N-Ser-Asp-Lys-Pro (AcSDKP) in a model of surgically induced hindlimb ischemia.

Methods and Results— Hindlimb ischemia was induced by femoral artery ligature and an osmotic minipump was implanted subcutaneously to deliver low (0.12 mg/kg per day) or high (1.2 mg/kg per day) doses of AcSDKP, for 7 or 21 days. Angiography scores, arteriole density, capillary number, and foot perfusion were increased at day 21 in the high-dose AcSDKP-treated mice (by 1.9-, 1.8-, 1.3-, and 1.6-fold, respectively) compared with control animals (P<0.05, P<0.01, P<0.01, respectively). AcSDKP treatment for 24 hours upregulated the monocyte chemoattractant protein-1 (MCP-1) mRNA and protein levels by 1.5-fold in cultured endothelial cells (P<0.01). In the ischemic hindlimb model, administration of AcSDKP also enhanced MCP-1 mRNA levels by 90-fold in ischemic leg (P<0.001) and MCP-1 plasma levels by 3-fold (P<0.001 versus untreated ischemic control mice). MCP-1 levels upregulation were associated with a 2.3-fold increase in the number of Mac3-positive cells in ischemic area of AcSDKP-treated mice (P<0.001 versus untreated animals). Interestingly, AcSDKP-induced monocyte/macrophage infiltration and postischemic neovascularization was fully blunted in MCP-1-deficient animals.

Conclusion— AcSDKP stimulates postischemic neovascularization through activation of a proinflammatory MCP-1-related pathway.

In this study, we investigated the putative proangiogenic activity and molecular pathway(s) of the tetrapeptide acetyl-N-Ser-Asp-Lees-Pro (AcSDKP) in a model of surgically induced hind limb ischemia. AcSDKP stimulated MCP-1 mRNA and protein levels in cultured endothelial cells and ischemic tissue. Subsequently, AcSDKP-induced MCP-1 upregulation activated monocytes/macrophages infiltration to ischemic areas and promoted postischemic neovascularization.


Key Words: angiogenesis • ischemia • inflammation • AcSDKP • MCP-1


*    Introduction
up arrowTop
up arrowAbstract
*Introduction
down arrowMaterials and Methods
down arrowResults
down arrowDiscussion
down arrowReferences
 
Postnatal neovascularization involves 3 principal processes, ie, vasculogenesis, angiogenesis, and collateral growth.1 Inflammation is one of the key events implicated in blood vessel growth, especially in the setting of ischemia. Both monocytes/macrophages and lymphocytes have been shown to adhere to the vascular wall, infiltrate in the ischemic tissue and increase production of cytokines such as IL-10 and IL-18,2,3 and growth factors like bFGF, tumor necrosis factor-{alpha}, granulocyte macrophage colony-stimulating factor and vascular endothelial growth factor.4–6 Accumulation of leukocytes at inflammatory sites is regulated by chemotactic low-molecular-weight proteins called chemokines. One of the chemokines, the monocyte chemoattractant protein-1 (MCP-1), promotes monocytes/macrophages recruitment through activation of its receptor CCR2,7,8 and subsequently accelerates ischemia-induced blood vessel growth.4,5,9 MCP-1 can also act as a direct mediator of angiogenesis.10 Similarly, CXCR3 and its ligand CXCL-10 positively modulate ischemia-induced neovascularization, likely through modulation of inflammatory cell infiltration.11 Therefore, modulators of inflammation play a critical role in determining the extent of neovascularization after ischemic injury.

The tetrapeptide Acetyl-Ser-Asp-Lys-Pro (AcSDKP), purified from bone marrow was originally described as a physiological negative regulator of hematopoiesis.12 It inhibits in vitro as well in vivo the proliferation of normal hematopoietic stem cells and committed progenitors.12 AcSDKP possibly generated from thymosin-ß413 is present in blood at nanomolar concentrations and is ubiquitously distributed in various tissues.14 In the circulation, AcSDKP is hydrolized by the NH2-terminal catalytic domain of angiotensin-converting enzyme (ACE)15 and its plasma level increases substantially during angiotensin-converting enzyme inhibitor (ACEI) administration.16 Thus, some of the effects of ACEI may be mediated by an increase in AcSDKP. Besides its role in the regulation of hematopoiesis, AcSDKP plays another biological function as a promoter of angiogenesis.17 It acts as a stimulator of endothelial cells migration and differentiation into capillary-like structures. AcSDKP induces neovascularization in the chicken embryo chorioallantoic membrane and abdominal muscle in rat. Recent finding also reports the ability of AcSDKP to upregulate capillary density in rat hearts with myocardial infarction.18 Taken together, these data prompted us to investigate the contribution of this tetrapeptide to neovascularization in a model of unilateral hindlimb ischemia.


*    Materials and Methods
up arrowTop
up arrowAbstract
up arrowIntroduction
*Materials and Methods
down arrowResults
down arrowDiscussion
down arrowReferences
 
Mouse Ischemic Hindlimb Model
Experiments were conducted according to the French veterinary guidelines. All experiments were performed in 10 weeks C57Bl/6 mice or C57Bl/6 MCP-1 deficient animals. Mice underwent surgery to induce unilateral hindlimb ischemia, as previously described.3 Briefly, animals were anesthetized by isoflurane inhaling. The ligature was performed on the proximal origin of the right femoral artery, just above the origin of the circumflexa femoris lateralis. An osmotic minipump was then subcutaneously implanted on the back of the ischemic mice (Alzet, type 2001 and 2004) to deliver low (0.12 mg/kg per day) or high (1.2 mg/kg per day) doses of AcSDKP (IPSEN-Biotech, Paris, France) for 7 or 21 days. A group of mice was also treated with MCP-1 (1.5 µg/kg per day, osmotic minipump) for 21 days. The control animals received osmotic minipump delivering saline solution.

Cell Culture
Immortalized EA.hy926 endothelial cells were grown in Dulbecco Minimal Essential Medium (DMEM) supplemented with 10% fetal calf serum. For cell-based enzyme linked immunosorbent assay (ELISA) and reverse-transcriptase–polymerase chain reaction (PCR) studies, EA.hy926 cells were seeded into 25-cm2 culture flask (Corning, VWR), grown to 90% confluence, and starved overnight in serum-free DMEM medium before stimulation. Cells were then incubated for 4 hours and 24 hours in serum-free DMEM in the absence or presence of AcSDKP at various concentrations. The cells and their supernatants were collected for determination of MCP-1 secreted protein and MCP-1 mRNA levels.

Cell Proliferation Assays
Human umbilical vein endothelial cells (Promocell, 5x103 cells) were plated in gelatin-coated 96-well plates (Becton Dickinson) and allowed to adhere for 24 hours. The medium was removed, and the cells were washed twice with serum-free EGM2 medium. Serum-free medium containing 0.1% FBS, AcSDKP 10–7 M, AcSDKP 10–9 M, or 5% FBS was then added. After incubation at 37°C for 8 hours, 1 µCi/mL [3H]thymidine (Amersham) was added and cells were incubated for 8 additional hours at 37°C. Thymidine incorporation was assessed using a TopCount NXT scintillation counter (Perkin Elmer).

ELISA Quantification of MCP-1
Blood was collected and centrifugated at 1600g for 15 minutes at 4°C, plasma was then removed, aliquoted, and frozen at –20°C. MCP-1 concentration was determined using the cross-reacting mouse JE/MCP-1 ELISA kit (R&D Systems). MCP-1 concentration in the supernatants of EA.hy926 endothelial cells was evaluated using the human MCP-1 ELISA kit (R&D Systems).

Determination of Plasma AcSDKP Levels
Blood was collected into pre-chilled heparinized tubes. Lisinopril (Sigma) was immediately added to the blood samples (10–6 M final concentration) to prevent AcSDKP degradation. Samples were centrifugated at 1600g for 15 minutes at 4°C and the plasma stored at –20°C until use. AcSDKP concentration was determined using a highly specific competitive enzyme immunoassay with acetylcholinesterase conjugate as a tracer (SPIbio) as previously described.17

Quantification of Neovascularization
Vessel density was evaluated by 4 different methods, as previously described3: (1) high-definition microangiography using barium sulfate (1 g/mL) injected in the abdominal aorta, followed by image acquisition with a digital X-ray transducer and computerized quantification of vessel density expressed as a percentage of pixels per image occupied by vessels in the quantification area; (2) assessment of capillary density by immunostaining with a rabbit polyclonal antibody directed against total fibronectin (dilution 1/50, Chemicon International); (3) evaluation of arteriole density by immunostaining using a mouse monoclonal antibody directed against human smooth muscle actin {alpha}-1 (dilution 1/50; Dako Cytomation); and (4) laser Doppler perfusion imaging to assess in vivo tissue foot perfusion.

Flow Cytometry Analysis of ScaI/c-kit–Positive Cells in Blood
Seven days after the onset of ischemia, mononuclear cells were isolated from peripheral blood (300 µL) of control and AcSDKP-treated mice. Mononuclear cells were then incubated with fluorescein isothiocyanate (FITC) conjugated monoclonal antibody against Sca-1 (D7) and phycoerythrin conjugated monoclonal antibody against c-kit (2B8) (all purchased from BD Pharmingen).

Isolation of Bone Marrow Mononuclear Cells and Endothelial Progenitor Cells Differentiation Assay
Bone marrow cells were obtained by flushing the tibias and femurs of control and AcSDKP treated mice for 7 days. Low-density bone marrow mononuclear cells (BM-MNCs) were then isolated by density gradient centrifugation with Ficoll, as previously described.2 Dual positive staining for both AcLDL-Dil and BS-1 lectin characterized endothelial progenitor cells (EPCs). EPCs were counted and the number was expressed in cells by field, as previously described.2,19 Results were expressed as percentage of total number of cultured cells. In the second set of experiments, BM-MNCs isolated from control mice were plated in the absence or presence of AcSDKP at various concentrations for 4 days and the number of EPCs was assessed, as described.

Flow Cytometry Analysis of Circulating CD45/CD11b–Positive Cells
Blood was collected from control and AcSDKP-treated mice, 7 days after the onset of ischemia. Low-density mononuclear cells were then isolated by density gradient centrifugation with Ficoll and incubated with antibody against CD45 (1:100; Pharmingen) and with antibody against CD11b (0.25 µg/million cells; BD Pharmingen) for 30 minutes at 4°C. The number of CD45/CD11b-positive cells was then analyzed by flow cytometry.

Real-Time Quantitative Reverse-Transcription PCR
Real-time quantitative reverse-transcription PCR was performed on a Light Cycler (Roche Diagnostics). Quantification was performed relative to glyceraldehyde-3-phosphate dehydrogenase (GAPDH) control. The sequence of primers used were, for MCP1: forward 5'-CTGGAGCATCCACGTGTTGG-3'; reverse 5'-CCCATTCCTTCTTGGGGTCA-3'; and for GAPDH: forward 5'-GACTGTGGATGGCCCCTCTG-3'; reverse 5'-GAGGTCCACCACCCTGTTGC-3'. The detection of amplification products was carried out using SYBR Green (Roche Applied Science). To confirm amplification specificity, the PCR products from each primer pair were subjected to melting curve analysis and subsequent agarose gel electrophoresis. For data analysis, Light Cycler 3.5 Software was used.

Immunohistochemistry
Seven-micrometer frozen tissue sections from the mouse gastrocnemius muscle were used for immunohistochemistry. Macrophages were identified with a rat monoclonal antibody directed against Mac-3 (1:50, BD Pharmingen). Tissues sections were then analyzed using avidin-biotin horseradish peroxydase visualization systems (Vectastain ABC kit elite; Vector Laboratories, Biovalley) and counterstained with hematoxylin. Mac-3–positive cells were counted in randomly fields in the ischemic area of gastrocnemius muscle using Histolab software. MCP-1 was detected in randomly fields of tissues sections with a goat polyclonal antibody against mouse JE/MCP-1 (1:20; R&D System) and with a fluorescent anti-goat antibody (1:50; Dako Cytomation).

Statistical Analysis
Results were expressed as mean±SEM. One-way analysis of variance ANOVA was used to compare each parameter. Post-hoc Bonferroni t test comparisons were then performed to identify which group differences account for the significant overall ANOVA. P<0.05 was considered significant.


*    Results
up arrowTop
up arrowAbstract
up arrowIntroduction
up arrowMaterials and Methods
*Results
down arrowDiscussion
down arrowReferences
 
Ischemia and Endogenous Synthesis of AcSDKP
We first analyzed the effect of ischemia on AcSDKP levels. We showed that ischemia enhanced AcSDKP plasma levels by 2.3-fold when compared with sham-operated animals (P<0.05; Figure Ia, available online at http://atvb.ahajournals.org). AcSDKP-positive staining was mainly observed around vascular structures. The number of capillary positive for AcSDKP tended to be higher in ischemic compared with nonischemic tissue but this difference did not reach statistical significance (Figure Ib).

AcSDKP Induces Neovascularization in Mouse Ischemic Hindlimb
To assess AcSDKP proangiogenic potential, postischemic neovascularization was analyzed in mice treated with low-dose (0.12 mg/kg per day) or high-dose (1.2 mg/kg per day) of AcSDKP for 7 or 21 days. AcSDKP treatment increased AcSDKP plasma levels by 3.7-fold (7.36±0.89 nM versus 1.99±0.42 nM in AcSDKP-treated mice versus control animals, respectively; P<0.05).

At day 7, angiographic score, capillary density and foot perfusion were not significantly affected in mice receiving 0.12 mg/kg per day or 1.2 mg/kg per day of AcSDKP. In contrast, at day 21, angiography scores, arteriole density, capillary number, and foot perfusion were increased in high-dose AcSDKP-treated mice by 1.9-, 1.8-, 1.3-, and 1.6-fold, respectively, compared with control animals (P<0.05, P<0.01, P<0.01, respectively) (Figures 1 and 2Down).


Figure 1
View larger version (33K):
[in this window]
[in a new window]
 
Figure 1. Representative photomicrographs and quantitative evaluation of microangiography (A) and capillary density (B) (capillary appears in green, arrows indicating representative examples of fibronectin-positive capillaries) in control animals and AcSDKP-treated mice with 0.12 mg/kg per day (AcSDKP 0.12) or 1.20 mg/kg per day (AcSDKP 1.20). Values are mean±SEM, n=7. *P<0.05, **P<0.01, ***P<0.001 vs control mice, ###P<0.001 vs ischemic calf muscle.


Figure 2
View larger version (23K):
[in this window]
[in a new window]
 
Figure 2. A, Representative photomicrographs and quantitative evaluation of foot perfusion in control mice and mice treated with AcSDKP at 0.12 mg/kg per day (AcSDKP 0.12) or 1.20 mg/kg per day (AcSDKP 1.20). Values are mean±SEM, n=7. ***P<0.01 vs control mice at day 21. B, Representative photomicrographs and quantitative evaluation of arterial density (arteriole appears in brown, arrows indicating representative examples of alpha actin smooth muscle-positive vessels) in ischemic and nonischemic muscle of control animals and AcSDKP-treated mice (1.20 mg/kg per day, AcSDKP 1.20). Values are mean±SEM, n=7. ***P<0.001 vs ischemic calf muscle of control mice, ##P<0.01 vs ischemic calf muscle of AcSDKP-treated animals.

AcSDKP Does Not Affect Endothelial Cell Proliferation
The observed in vivo efficacy of AcSDKP to improve vessel growth in the ischemic hindlimb prompted us to determine the molecular and cellular mechanisms involved in this process. An increase in capillary number following AcSDKP administration suggests that this tetrapeptide may affect endothelial cells proliferation. To address this hypothesis, we analyzed the effect of AcSDKP on EA.hy926 endothelial cells and human umbilical vein endothelial cells proliferation. However, proliferation of endothelial cells was not modulated by AcSDKP treatment in our experimental conditions, whatever the type of endothelial cells (Figure IIa, IIb, and IIc, available online at http://atvb.ahajournals.org).

AcSDKP Does Not Affect BM-MNC Differentiation Into EPC
Neovascularization does not rely exclusively on sprouting of pre-existing vessels, it also involves postnatal vasculogenesis. In response to ischemia, a subset of EPC was shown as being mobilized from bone marrow, they incorporate the ischemic area and participate to vessel growth.20,21 Furthermore, AcSDKP was previously reported to regulate the proliferation of bone marrow-derived hematopoietic CD34+ stem cells.22 We therefore analyzed the effect of AcSDKP on the mobilization of BM-MNC and their differentiation into EPC.

BM-MNC Mobilization
EPC are thought to derive from Sca-1/c-kit–positive mononuclear cells.20 Nevertheless, the percentage of Sca-1/c-kit–positive mononuclear cells in the peripheral blood remained unchanged in AcSDKP-treated mice compared with untreated animals (Figure IId).

BM-MNC Differentiation Into EPC
BM-MNC were isolated from control and AcSDKP-treated mice and then cultured for 4 additional days on gelatin/vitronectin. AcSDKP administration had no effect on the number of EPC derived from BM-MNC (Figure IIe). Furthermore, BM-MNC differentiation into EPC was unaffected when BM-MNC were isolated from untreated mice and next cultured for 4 days in presence of 10–7 M AcSDKP (data not shown). Taken together, these results suggest that AcSDKP promoted postischemic neovascularization without affecting postnatal vasculogenesis.

AcSDKP Activates Inflammatory Reaction
The lack of effect of AcSDKP on endothelial cell proliferation and BM-MNC led us to hypothesize that AcSDKP may enhance vessel growth by activating the inflammatory reaction.

AcSDKP Increases the Number of CD45/CD11b-Positive Cells in Blood
We analyzed the role of AcSDKP on the monocytes/macrophages mobilization. The number of circulating CD45/CD11b-positive cells in blood was determined by flow cytometry. Treatment with AcSDKP (1.2 mg/kg per day) for 7 days increased the number of circulating CD45/CD11b-positive cells by 1.4-fold compared with controls (18.0±1.1% versus 13.1±1.3% for AcSDKP-treated mice versus untreated mice, respectively; P<0.05).

AcSDKP Increases Macrophages Infiltration in Ischemic Area
Similarly, the number of infiltrated macrophages in ischemic area of AcSDKP-treated mice was increased by 2.3-fold compared with control mice, 7 days after the onset of ischemia (9.67±0.2 cells/mm2 versus 4.2±0.6 cells/mm2 for AcSDKP-treated mice versus untreated mice, respectively; P<0.001). Hence, AcSDKP was shown to enhance inflammatory reaction in ischemic tissue.

AcSDKP Activates MCP-1 Signaling
We next sought to define the molecular pathway involved in AcSDKP-induced activation of inflammation. It is well-known that accumulation of leukocytes at inflammatory sites is regulated by chemokines. Among them, MCP-1 represents a major critical rate-limiting step in monocytes/macrophages infiltration in ischemic area.5,9

AcSDKP Induces MCP-1 Secretion by Endothelial Cells In Vitro
We first investigated the effect of AcSDKP on MCP-1 levels in endothelial cells. AcSDKP (10–7 M) was shown to increase MCP-1 mRNA levels by 1.5-fold compared with untreated endothelial cells (P<0.05; Figure 3a). AcSDKP also upregulated MCP-1 protein content in the supernatant of treated endothelial cells (1811±360 pg/mL versus 1465±313 pg/mL, respectively; P<0.001; Figure 3b).


Figure 3
View larger version (44K):
[in this window]
[in a new window]
 
Figure 3. Quantitative evaluation of MCP-1 mRNA (A) and protein (B) levels in endothelial cells cultured for 24 hours with or without 10–11 M and 10–7 M of AcSDKP. Values are mean±SEM, n=9. **P<0.01 vs untreated cells. C, Quantitative evaluation of MCP-1 mRNA levels in ischemic and non ischemic calf muscle of mice treated with or without AcSDKP at 1.20 mg/kg per day (AcSDKP 1.20), 7 days (D7) after ischemia. Values are mean±SEM, n=6. *P<0.05, **P<0.01 vs ischemic control calf, #P<0,05 vs ischemic AcSDKP-treated calf. D, Quantitative evaluation of MCP-1 plasma levels in mice treated with or without 1.20 mg/kg per day (AcSDKP 1.20) of AcSDKP, 7 days (D7) after ischemia. Values are mean±SEM, n=6. ***P<0.001 vs control. E, Representative photomicrographs of MCP-1–positive staining in ischemic calf muscle of mice treated with or without AcSDKP, at day 7 (D7) after ischemia. Arrows indicate representative examples of MCP-1–positive cells.

AcSDKP Increases MCP-1 mRNA and Protein Levels In Vivo
We next determined the effect of AcSDKP on MCP-1 levels in vivo in the ischemic hindlimb model. Ischemia enhances MCP-1 mRNA level by 12-fold compared with nonischemic tissue (P<0.05; Figure 3c). Furthermore, AcSDKP (1.2 mg/kg per day) increases MCP-1 mRNA content by 90-fold compared with control ischemic mice (P<0.01; Figure 3c). Administration of AcSDKP also raised MCP-1 plasma levels by 3-fold compared with control ischemic mice (P<0.001) (Figure 3d). Finally, MCP-1–positive staining was mainly localized around capillaries of ischemic tissue and was markedly improved by AcSDKP treatment (Figure 3e).

AcSDKP Proangiogenic Effect Required MCP-1–Related Pathway
We next analyzed the requirement of MCP-1 in AcSDKP-induced neovascularization using mice deficient for MCP-1.

Postischemic Neovascularization
AcSDKP treatment increased angiography scores, capillary numbers and foot perfusion by 1.7-, 1.4-, and 1.6-fold in wild-type mice compared with untreated animals (P<0.05 versus untreated wild-type mice). This effect was fully blunted in MCP-1–deficient mice. In addition, MCP-1 treatment enhanced revascularization in wild-type animals supporting the hypothesis that MCP-1 plays a pivotal role in vessel growth in this setting (Figure 4a, 4b, and 4c).


Figure 4
View larger version (41K):
[in this window]
[in a new window]
 
Figure 4. Quantitative evaluation of microangiography (A), capillary density (B), and foot perfusion (C) in wild-type or MCP-1–deficient (MCP1KO) mice treated with or without AcSDKP (1.20 mg/kg per day, MCP-1KO + AcSDKP 1.20) or MCP-1 (1.5 µg/kg per day), 21 days after the onset of ischemia. Values are mean±SEM, n=6. *P<0.05, **P<0.01 vs untreated wild-type mice, {dagger}{dagger}{dagger}P<0.001 vs AcSDKP-treated wild-type animals. D, Representative photomicrographs and quantitative evaluation of Mac3-positive cells in calf muscle of wild-type or MCP-1–deficient (MCP1KO) mice treated with or without AcSDKP at 1.20 mg/kg per day (MCP1KO + AcSDKP 1.20), 21 days after the onset of ischemia. Values are mean±SEM, n=6. ***P<0.001 vs untreated wild-type mice, {dagger}{dagger}{dagger}P<0.001 vs AcSDKP-treated wild-type animals, !=!=P<0.01 vs untreated MCP-1–deficient animals.

Inflammatory Reaction
Changes in neovascularization were associated with modulation of the inflammatory reaction. At day 21 after the onset of ischemia, few macrophages were seen in the interstitial space of control mice. The number of tissue infiltrated macrophages markedly increased in wild-type mice treated with 1.2 mg/kg per day of AcSDKP compared with untreated mice (P<0.001). In contrast, AcSDKP-induced macrophages infiltration was abrogated in MCP-1–deficient mice (Figure 4d).


*    Discussion
up arrowTop
up arrowAbstract
up arrowIntroduction
up arrowMaterials and Methods
up arrowResults
*Discussion
down arrowReferences
 
The main results of this study reveal the efficacy of AcSDKP to improve postischemic neovascularization in the context of hindlimb ischemia. A detailed analysis of the molecular and cellular mechanisms involved in this effect suggests an activation of the proinflammatory MCP-1–related pathway.

AcSDKP, an endogenous tetrapeptide produced constitutively by the endothelium, is a potent angiogenic factor both in vitro and in vivo.23 We could extend those observations showing that AcSDKP also promotes postischemic neovascularization. The proangiogenic effect of AcSDKP is not mediated by activation of endothelial cells proliferation. In addition, although AcSDKP modulates primitive hematopoietic stem cells proliferation and probably their homing, we do not observe any effect of AcSDKP on BM-MNC differentiation into EPC. Alternatively, our results suggest that AcSDKP enhances endothelial cells ability to produce MCP-1. MCP-1 may activate specific pathways involved in the angiogenic phenotype. MCP-1 upregulates hypoxia-inducible factor 1 alpha gene expression and subsequently vascular endothelial growth factor-A (165) expression.24 In addition, MCP-1 induces chemotaxis of human endothelial cells at nanomolar concentrations in the absence of leukocytic infiltrates.10 MCP-1 also represents a major critical rate-limiting step in monocytes/macrophages infiltration in ischemic area. Exogenous administration of MCP-1 or a deficiency in its receptor, CCR2, regulate monocyte recruitment in the adventitia of growing arteries after vessel occlusion.5,9 Monocytes accumulation and activation play a pivotal role in collateral growth and angiogenesis by secretion of key angiogenic factor such as tumor necrosis factor-{alpha}, bFGF, or vascular endothelial growth factor.4,6,25 In addition, we evidenced that AcSDKP-induced monocytes/macrophages infiltration is fully blunted in MCP-1–deficient mice suggesting that MCP-1 is an upstream regulator of inflammation in AcSDKP-related pathway. Taken together, the present findings suggest that AcSDKP enhances MCP-1 production by endothelial cells and thereby attracts monocytes/macrophages in ischemic area to promote neovascularization.

AcSDKP was shown to enhance the conversion of the prometalloproteinase-1 into its active form,23 suggesting that this tetrapeptide is able to stimulate the acute phases of neovascularization characterized by matrix degradation and inflammatory cells infiltration. Surprisingly, AcSDKP partially prevented and reversed the inflammatory reaction within the heart.26 The reason of this discrepancy is unclear but, in this latter study, AcSDKP was administered up to 4 months after the onset of ischemia. In the ischemic hindlimb model, inflammation plays a major role during the acute phase of neovascularization.11 Therefore, long-term administration as well as the remodeling process occurring in the treated heart might explain the difference in AcSDKP-related effects on inflammation between ischemic heart and hindlimb.

Our study highlights the concept that AcSDKP may be involved in angiogenesis-related diseases. In support of this view, AcSDKP serum levels are increased in adult patients with hematologic malignancies.27 Upexpression of thymosin ß4, the putative precursor of AcSDKP, also occurs in neoplastic tissues28 suggesting that AcSDKP may be implicated in different pathological states characterized by activation of angiogenesis. A growing body of evidences suggest that ACEI promotes postischemic neovascularization.29–31 Treatment with ACEI also increases AcSDKP concentration in plasma highlighting the hypothesis that AcSDKP may partially mediate ACEI proangiogenic potential.32

In conclusion, this study provides the first evidence to our knowledge that AcSDKP improves MCP-1–dependent postischemic neovascularization and supports the concept that AcSDKP administration might constitute a potential therapeutic strategy in the treatment of ischemic diseases. However, MCP-1 and inflammation have been shown to promote atherosclerotic plaque growth, suggesting putative side effects of AcSDKP-induced MCP-1 upregulation.2,33 Further studies should determine whether therapeutic angiogenic strategy based on systemic and/or local administration of AcSDKP may promote side effects especially in the setting of atherosclerosis.


*    Acknowledgments
 
J.S.S. is supported by grants from ANR "young investigator" (JC05-45445) and ANR 2005 "Cardiovascular, Obesity and Diabetes, ANR-05-PCOD-028-01." B.M. is a recipient of grants from The Netherlands Organization for Health Research and Development (Agiko Stipend 920-03-291).

Received July 20, 2005; accepted January 3, 2006.


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

  1. Carmeliet P. Mechanisms of angiogenesis and arteriogenesis. Nat Med. 2000; 6: 389–395.[CrossRef][Medline] [Order article via Infotrieve]
  2. Mallat Z, Silvestre JS, Le Ricousse-Roussanne S, Lecomte-Raclet L, Corbaz A, Clergue M, Duriez M, Barateau V, Akira S, Tedgui A, Tobelem G, Chvatchko Y, Levy BI. Interleukin-18/interleukin-18 binding protein signaling modulates ischemia-induced neovascularization in mice hindlimb. Circ Res. 2002; 91: 441–448.[Abstract/Free Full Text]
  3. Silvestre JS, Mallat Z, Duriez M, Tamarat R, Bureau MF, Scherman D, Duverger N, Branellec D, Tedgui A, Levy BI. Antiangiogenic effect of interleukin-10 in ischemia-induced angiogenesis in mice hindlimb. Circ Res. 2000; 87: 448–452.[Abstract/Free Full Text]
  4. Arras M, Ito WD, Scholz D, Winkler B, Schaper J, Schaper W. Monocyte activation in angiogenesis and collateral growth in the rabbit hindlimb. J Clin Invest. 1998; 101: 40–50.[Medline] [Order article via Infotrieve]
  5. Heil M, Ziegelhoeffer T, Pipp F, Kostin S, Martin S, Clauss M, Schaper W. Blood monocyte concentration is critical for enhancement of collateral artery growth. Am J Physiol Heart Circ Physiol. 2002; 283: H2411–2419.[Abstract/Free Full Text]
  6. Stabile E, Burnett MS, Watkins C, Kinnaird T, Bachis A, la Sala A, Miller JM, Shou M, Epstein SE, Fuchs S. Impaired arteriogenic response to acute hindlimb ischemia in CD4-knockout mice. Circulation. 2003; 108: 205–210.[Abstract/Free Full Text]
  7. Olson TS, Ley K. Chemokines and chemokine receptors in leukocyte trafficking. Am J Physiol Regul Integr Comp Physiol. 2002; 283: R7–R28.[Abstract/Free Full Text]
  8. Fuentes ME, Durham SK, Swerdel MR, Lewin AC, Barton DS, Megill JR, Bravo R, Lira SA. Controlled recruitment of monocytes and macrophages to specific organs through transgenic expression of monocyte chemoattractant protein-1. J Immunol. 1995; 155: 5769–5776.[Abstract]
  9. Ito WD, Arras M, Winkler B, Scholz D, Schaper J, Schaper W. Monocyte chemotactic protein-1 increases collateral and peripheral conductance after femoral artery occlusion. Circ Res. 1997; 80: 829–837.[Abstract/Free Full Text]
  10. Salcedo R, Ponce ML, Young HA, Wasserman K, Ward JM, Kleinman HK, Oppenheim JJ, Murphy WJ. Human endothelial cells express CCR2 and respond to MCP-1: direct role of MCP-1 in angiogenesis and tumor progression. Blood. 2000; 96: 34–40.[Abstract/Free Full Text]
  11. Waeckel L, Mallat Z, Potteaux S, Combadiere C, Clergue M, Duriez M, Bao L, Gerard C, Rollins BJ, Tedgui A, Levy BI, Silvestre JS. Impairment in postischemic neovascularization in mice lacking the CXC chemokine receptor 3. Circ Res. 2005; 96: 576–582.[Abstract/Free Full Text]
  12. Lenfant M, Wdzieczak-Bakala J, Guittet E, Prome JC, Sotty D, Frindel E. Inhibitor of hematopoietic pluripotent stem cell proliferation: purification and determination of its structure. Proc Natl Acad Sci U S A. 1989; 86: 779–782.[Abstract/Free Full Text]
  13. Cavasin MA, Rhaleb NE, Yang XP, Carretero OA. Prolyl oligopeptidase is involved in release of the antifibrotic peptide Ac-SDKP. Hypertension. 2004; 43: 1140–1145.[Abstract/Free Full Text]
  14. Pradelles P, Frobert Y, Creminon C, Ivonine H, Frindel E. Distribution of a negative regulator of haematopoietic stem cell proliferation (AcSDKP) and thymosin beta 4 in mouse tissues. FEBS Lett. 1991; 289: 171–175.[CrossRef][Medline] [Order article via Infotrieve]
  15. Rousseau A, Michaud A, Chauvet MT, Lenfant M, Corvol P. The hemoregulatory peptide N-acetyl-Ser-Asp-Lys-Pro is a natural and specific substrate of the N-terminal active site of human angiotensin-converting enzyme. J Biol Chem. 1995; 270: 3656–3661.[Abstract/Free Full Text]
  16. Azizi M, Ezan E, Nicolet L, Grognet JM, Menard J. High plasma level of N-acetyl-seryl-aspartyl-lysyl-proline: a new marker of chronic angiotensin-converting enzyme inhibition. Hypertension. 1997; 30: 1015–1019.[Abstract/Free Full Text]
  17. Liu JM, Lawrence F, Kovacevic M, Bignon J, Papadimitriou E, Lallemand JY, Katsoris P, Potier P, Fromes Y, Wdzieczak-Bakala J. The tetrapeptide AcSDKP, an inhibitor of primitive hematopoietic cell proliferation, induces angiogenesis in vitro and in vivo. Blood. 2003; 101: 3014–3020.[Abstract/Free Full Text]
  18. Wang D, Carretero OA, Yang XY, Rhaleb NE, Liu YH, Liao TD, Yang XP. N-acetyl-seryl-aspartyl-lysyl-proline stimulates angiogenesis in vitro and in vivo. Am J Physiol Heart Circ Physiol. 2004; 287: H2099–H2105.[Abstract/Free Full Text]
  19. Tamarat R, Silvestre JS, Le Ricousse-Roussanne S, Barateau V, Lecomte-Raclet L, Clergue M, Duriez M, Tobelem G, Levy BI. Impairment in ischemia-induced neovascularization in diabetes: bone marrow mononuclear cell dysfunction and therapeutic potential of placenta growth factor treatment. Am J Pathol. 2004; 164: 457–466.[Abstract/Free Full Text]
  20. Takahashi T, Kalka C, Masuda H, Chen D, Silver M, Kearney M, Magner M, Isner JM, Asahara T. Ischemia- and cytokine-induced mobilization of bone marrow-derived endothelial progenitor cells for neovascularization. Nat Med. 1999; 5: 434–438.[CrossRef][Medline] [Order article via Infotrieve]
  21. Asahara T, Masuda H, Takahashi T, Kalka C, Pastore C, Silver M, Kearne M, Magner M, Isner JM. Bone marrow origin of endothelial progenitor cells responsible for postnatal vasculogenesis in physiological and pathological neovascularization. Circ Res. 1999; 85: 221–228.[Abstract/Free Full Text]
  22. Bonnet D, Lemoine FM, Pontvert-Delucq S, Baillou C, Najman A, Guigon M. Direct and reversible inhibitory effect of the tetrapeptide acetyl-N-Ser-Asp-Lys-Pro (Seraspenide) on the growth of human CD34+ subpopulations in response to growth factors. Blood. 1993; 82: 3307–3314.[Abstract/Free Full Text]
  23. Chisi JE, Briscoe CV, Ezan E, Genet R, Riches AC, Wdzieczak-Bakala J. Captopril inhibits in vitro and in vivo the proliferation of primitive haematopoietic cells induced into cell cycle by cytotoxic drug administration or irradiation but has no effect on myeloid leukaemia cell proliferation. Br J Haematol. 2000; 109: 563–570.[CrossRef][Medline] [Order article via Infotrieve]
  24. Hong KH, Ryu J, Han KH. Monocyte chemoattractant protein-1-induced angiogenesis is mediated by vascular endothelial growth factor-A. Blood. 2005; 105: 1405–1407.[Abstract/Free Full Text]
  25. Silvestre JS, Tamarat R, Ebrahimian TG, Le-Roux A, Clergue M, Emmanuel F, Duriez M, Schwartz B, Branellec D, Levy BI. Vascular endothelial growth factor-B promotes in vivo angiogenesis. Circ Res. 2003; 93: 114–123.[Abstract/Free Full Text]
  26. Yang F, Yang XP, Liu YH, Xu J, Cingolani O, Rhaleb NE, Carretero OA. Ac-SDKP reverses inflammation and fibrosis in rats with heart failure after myocardial infarction. Hypertension. 2004; 43: 229–236.[Abstract/Free Full Text]
  27. Liozon E, Volkov L, Comte L, Trimoreau F, Pradelles P, Bordessoule D, Frindel E, Praloran V. AcSDKP serum concentrations vary during chemotherapy in patients with acute myeloid leukaemia. Br J Haematol. 1995; 89: 917–920.[Medline] [Order article via Infotrieve]
  28. Clark EA, Golub TR, Lander ES, Hynes RO. Genomic analysis of metastasis reveals an essential role for RhoC. Nature. 2000; 406: 532–535.[CrossRef][Medline] [Order article via Infotrieve]
  29. Fabre JE, Rivard A, Magner M, Silver M, Isner JM. Tissue inhibition of angiotensin-converting enzyme activity stimulates angiogenesis in vivo. Circulation. 1999; 99: 3043–3049.[Abstract/Free Full Text]
  30. Silvestre JS, Bergaya S, Tamarat R, Duriez M, Boulanger CM, Levy BI. Proangiogenic effect of angiotensin-converting enzyme inhibition is mediated by the bradykinin B(2) receptor pathway. Circ Res. 2001; 89: 678–683.[Abstract/Free Full Text]
  31. Ebrahimian TG, Tamarat R, Clergue M, Duriez M, Levy BI, Silvestre JS. Dual effect of angiotensin-converting enzyme inhibition on angiogenesis in type 1 diabetic mice. Arterioscler Thromb Vasc Biol. 2005; 25: 65–70.[Abstract/Free Full Text]
  32. Azizi M, Rousseau A, Ezan E, Guyene TT, Michelet S, Grognet JM, Lenfant M, Corvol P, Menard J. Acute angiotensin-converting enzyme inhibition increases the plasma level of the natural stem cell regulator N-acetyl-seryl-aspartyl-lysyl-proline. J Clin Invest. 1996; 97: 839–844.[Medline] [Order article via Infotrieve]
  33. van Royen N, Hoefer I, Bottinger M, Hua J, Grundmann S, Voskuil M, Bode C, Schaper W, Buschmann I, Piek JJ. Local monocyte chemoattractant protein-1 therapy increases collateral artery formation in apolipoprotein E-deficient mice but induces systemic monocytic CD11b expression, neointimal formation, and plaque progression. Circ Res. 2003; 92: 218–225.[Abstract/Free Full Text]




This Article
Right arrow Abstract Freely available
Right arrow Full Text (PDF)
Right arrow Data Supplement
Right arrow All Versions of this Article:
26/4/773    most recent
01.ATV.0000203510.96492.14v1
Right arrow Alert me when this article is cited
Right arrow Alert me if a correction is posted
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 Google Scholar
Google Scholar
Right arrow Articles by Waeckel, L.
Right arrow Articles by Silvestre, J.-S.
Right arrow Search for Related Content
PubMed
Right arrow PubMed Citation
Right arrow Articles by Waeckel, L.
Right arrow Articles by Silvestre, J.-S.