Reduced CD26 expression is associated with improved cardiac function after acute myocardial infarction

Journal of Molecular and Cellular Cardiology 53 (2012) 899–905

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Original article

Reduced CD26 expression is associated with improved cardiac function after acute myocardial infarction Insights from the REPERATOR study Simone Post a, b, c,⁎, Alexandra J. van den Broek a, Benno J. Rensing b, Gerard Pasterkamp a, c, Marie-José Goumans a, d, Pieter A. Doevendans a, c a

University Medical Center, Division Heart & Lungs, Laboratory Experimental Cardiology, G02-523, Postbus 85500, 3508 GA Utrecht, The Netherlands Department of Cardiology, St. Antonius Hospital, Postbus 2500, 3430 EM Nieuwegein, The Netherlands c Interuniversity Cardiology Institute of the Netherlands (ICIN), Postbus 19258, 3501 DG Utrecht, The Netherlands d Leiden University Medical Center, Department of Molecular Cell Biology, Postbus 9600, 2300 RC Leiden, The Netherlands b

a r t i c l e

i n f o

Article history: Received 7 August 2012 Accepted 31 August 2012 Available online 9 September 2012 Keywords: Myocardial infarction Homing Blood cells Magnetic resonance imaging Remodeling CD26

a b s t r a c t Peripheral blood mononuclear cells (MNC) enhance cardiac recovery and repair after myocardial infarction (MI). The SDF-1α/CXCR4 axis plays a major role in cell homing to infarcted myocardium and is negatively regulated by CD26. Therefore, we studied the expression of CD26 during MI and its effects on cardiac function. Blood samples from forty-two patients who underwent a primary percutaneous coronary intervention (PCI) for a first ST-elevated MI were collected during primary PCI, 1 week and 3 months after MI. Soluble CD26 (sCD26) and membrane bound CD26 expression on MNCs (mncCD26) were determined. Left ventricular function and infarct size were measured within 1 day, 1 week and 3 months follow up by magnetic resonance imaging. One week post MI, sCD26 was down regulated compared to baseline, while mncCD26 was higher at baseline and 1 week compared to 3 months. Increased mncCD26 expression at 1 week after MI was associated with decreased overall recovery of left ventricular function as measured by left ventricular end systolic volume index. Furthermore, the in vitro migration capacity of MNCs to SDF-1α was decreased 1 week post MI and the migration capacity to SDF-1α was negatively correlated with mncCD26 expression. CD26 inhibition with sitagliptin – a drug currently used in diabetic patients – resulted in improved in vitro migration capacities of MNCs. In conclusion, our preliminary results suggest that high cellular CD26 expression decreases the migration of MNCs towards SDF-1α and high cellular CD26 expression negatively influences cardiac function post MI. Treating patients shortly post MI with sitagliptin to inhibit CD26 may therefore increase MNC homing to the infarct area and could improve cardiac recovery and repair. © 2012 Elsevier Ltd. All rights reserved.

1. Introduction Myocardial infarction (MI) is the leading cause of death worldwide [1]. Despite the modern management of MI with for example beta-blockers, statins and percutaneous coronary intervention (PCI), MI still has a high morbidity due to heart failure and/or arrhythmia: Abbreviations: DPPV, dipeptidylpeptidase IV; LV, left ventricle; LVESVI, left ventricle end-systolic volume index; MI, myocardial infarction; MNC, mononuclear cell; mncCD26, membrane bound CD26 expression on MNCs; PEA, percentage enhanced area; PCI, percutaneous coronary intervention; SDF-1α, stromal cell-derived factor-1α; sCD26, soluble CD26. ⁎ Corresponding author at: University Medical Center, Division Heart & Lungs, Laboratory Experimental Cardiology, G02-523, Postbus 85500, 3508 GA Utrecht, The Netherlands. Tel.: +31 88 755 7155; fax: +31 252 2693. E-mail addresses: [email protected] (S. Post), [email protected] (A.J. van den Broek), [email protected] (B.J. Rensing), [email protected] (G. Pasterkamp), [email protected] (M.-J. Goumans), [email protected] (P.A. Doevendans). 0022-2828/$ – see front matter © 2012 Elsevier Ltd. All rights reserved. http://dx.doi.org/10.1016/j.yjmcc.2012.08.026

the 1-month mortality is 4–9% [2,3]. New treatment modalities are needed to prevent post-MI adverse remodeling. Both bone marrow and peripheral blood mononuclear cells (MNCs) are currently tested in clinical studies where they are infused intracoronary following successful reperfusion in MI patients. These MNCs were shown to modestly improve cardiac recovery and repair [4–7]. The mechanism by which MNCs improve cardiac function is not fully understood, but homing of MNCs is an important feature to be able to integrate in the damaged myocardial wall. A key chemokine regulating directed cellular migration is stromal cell-derived factor-1α (SDF-1α or CXCL12) [8]. SDF-1α is upregulated in the ischemic myocardium shortly after MI, resulting in recruitment of cells expressing the SDF-1α receptor CXCR4 on their surface from the circulation into the ischemic area of the heart [9]. The SDF-1α/CXCR4 homing axis is negatively regulated by the peptidase CD26 (dipeptidylpeptidase IV (DPPIV)) which cleaves the amino-terminal dipeptide from SDF-1α, generating an inactive protein [10,11]. Recently we showed

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S. Post et al. / Journal of Molecular and Cellular Cardiology 53 (2012) 899–905

that the dysfunctional homing capacity of MNCs from patients with the vascular disease Hereditary Hemorrhagic Telangiectasia type 1 to the infarcted myocardium was related to increased CD26 levels [12,13]. Therefore, we hypothesize that in patients with MI, high CD26 expression is negatively associated with the homing capacity of MNCs to the infarcted area and a reduced preservation of cardiac function. 2. Materials and methods 2.1. Patient population and study design Between March 2006 and November 2007 forty-two patients were analyzed in the REPERATOR trial (Prevention of REPERfusion Damage and Late Left Ventricular Remodeling With ATORvastatin Administered Before Reperfusion Therapy) [14]. Patients were included in the St. Antonius Hospital Nieuwegein and University Medical Center Utrecht, The Netherlands. The current study was performed as a sub-study of the REPERATOR study in all forty-two patients. All patients presented with a first acute ST-elevation-MI and were treated with primary PCI. At inclusion, patients were randomized to treatment with atorvastatin 80 mg or placebo once daily starting prior to primary PCI. From day eight after PCI all patients were treated with atorvastatin 80 mg once daily. This study revealed that pretreatment with atorvastatin did not result in an improved cardiac function or decreased myocardial infarction size [15]. Furthermore, we included ten patients with stable coronary artery disease. These patients were scheduled for coronary angiography or elective PCI and had documented coronary artery disease. The investigation was approved by the medical ethics committee of both hospitals and conforms to the principles outlined in the Declaration of Helsinki. Written informed consent was obtained from all patients. The REPERATOR trial was registered at ClinicalTrials.gov under identification number NCT00286312. 2.2. Magnetic resonance imaging Early and late left ventricular function and infarct size were assessed by MRI (1.5 T Philips®, Best, The Netherlands), at baseline (within 24 h after inclusion), at 7 days and 3 months after MI. Steady state free precession cine sequences and gadolinium-enhanced images were analyzed using a 12 segment, 6–20 slice model. One observer blinded for treatment from one of the study centers interpreted the MRI scans. Left ventricle end-systolic volume (LVESV), left ventricle end-diastolic volume (LVEDV), left ventricle ejection fraction (EF), cardiac output (CO), percentage enhanced area (PEA) and percentage transmural infarcted area were calculated. 2.3. Blood samples Blood was drawn before PCI, at second and third MRI. Blood samples were collected in Potassium/EDTA tubes (Vacuette, Greiner Bio-One, The Netherlands). Plasma samples were frozen and stored at − 80 °C. Peripheral blood MNCs were isolated by density gradient centrifugation using Ficoll Paque Plus (Amersham Biosciences, Sweden), according to the manufacturer's protocol. 2.4. Flow cytometry Flow cytometric analysis was performed using 100 μL whole blood or 3 ∗ 10 E5 MNCs in PBS. Cells were stained according to the manufacturer's instructions using the following monoclonal mouseanti-human antibody combination: anti-CD14-ECD (Immunotech, Coulter, France), anti-CD26-FITC (Serotec, UK) and anti-CXCR4-PE (BD Pharmingen, USA). Isotype-matched fluorochrome-conjugated antibodies were used as controls. After incubation, samples were

Table 1 Patient characteristics. n = 42 Age, years Gender (male), n (%) Body mass index, kg/m2

57.0 ± 13.5 32 (76.2) 27.2 ± 4.0

Laboratory parameters Cholesterol, mmol/L‡ HDL-cholesterol, mmol/L|| LDL, mmol/L|| Triglycerides, mmol/L|| Glucose, mmol/L* Creatinin, μmol/L Hemoglobin, mmol/L Leucocytes, G/L

4.38 ± 1.27 0.82 ± 0.36 2.90 ± 1.30 1.15 ± 0.56 7.5 ± 4.5 80.5 ± 28.5 8.90 ± 1.05 11.1 ± 4.2

Medications after myocardial infarction Thrombocyte coagulation inhibitors, n (%) Statin, n (%) ACE-inhibitors, n (%)‡ Beta-blockers, n (%)‡ Angiotensin-II-receptor antagonists, n (%)‡ Calcium antagonists, n (%)‡

42 (100) 42 (100) 23 (54.8) 36 (85.7) 3 (7.1) 4 (9.5)

Myocardial infarction Anterior infarction, n (%) Total ischemic time, minutes Peak CK, U/L

10 (23.8) 168 ± 151 1198 ± 1596

Risk factors Smoking/history of smoking, n (%) Diabetes, n (%) Hypertension, n (%) Hypercholesterolemia, n (%)‡ Positive family history, n (%)

32 (76.2) 6 (14.3) 16 (38.1) 10 (23.8) 20 (47.6)

Data are presented as number (percentage) or medium±IQR. * n=36; ‡ n=41; ||n=40; due to missing data. ACE=angiotensin converting enzyme.

washed and, in whole blood samples, red blood cells were lysed before measuring fluorescence on a flow cytometer (Cytomics FC500, Beckman Coulter, The Netherlands). The MNC cell fraction was determined by forward and sideward scatter patterns. Analysis was

Table 2 Cardiac function and infarction size.

Cardiac function LVESVI, mL/m2 LVESV, mL LVEDV, mL EF, % CO, L/min Infarction area PEA (%)

baseline

1 week after AMI

27.6 ± 11.6 55.6 ± 24.3 115.6 ± 31.2 53.0 ± 11.2* 4.22 ± 0.91

27.8 ± 11.3 55.6 ± 22.4 122.5 ± 30.3 55.3 ± 10.9 4.28 ± 1.10

25.1 ± 9.7 50.7 ± 19.9 117.8 ± 30.4 57.9 ± 10.9 4.11 ± 0.94

15.0 ± 11.5

14.1 ± 10.3

18.7 ± 12.4*§

13 weeks after AMI

Change, time after AMI 1 vs. 0 weeks

13 vs. 0 weeks

13 vs. 1 weeks

Cardiac function LVESVI, mL/m2 LVESV, mL LVEDV, mL EF, % CO, L/min

0.11 ± 7.1 −0.16 ± 14.4 6.7 ± 19.7 2.4 ± 6.5 0.077 ± 0.94

−3.0 ± 10.0 −5.9 ± 20.1 1.5 ± 26.5 5.4 ± 7.4 −0.095 ± 0.78

2.8 ± 9.1 5.3 ± 18.3 4.9 ± 23.5 −2.8 ± 7.6 0.20 ± 0.89

−3.0 ± 3.3

−5.2 ± 5.2

−2.0 ± 4.8

Infarction area PEA (%)

Overview of parameters and change of cardiac function and PEA measured by MRI. Data are presented as mean or percentage ± SD. *P = 0.001 baseline versus 13 weeks after AMI; §P = 0.001 baseline versus 1 week after AMI. LVESVI=left ventricular end-systolic volume index; LVEDV=left ventricular end-diastolic volume; EF=ejection fraction CO=cardiac output; PEA=percentage enhanced area.

S. Post et al. / Journal of Molecular and Cellular Cardiology 53 (2012) 899–905

A

B

*

mncCD26 expression, MFI

Plasma sCD26, ng/mL

10

*

600

300

1 week after MI

6

3 months after MI

3

baseline

D

2

1

0 baseline

1 week after MI

3 months after MI

Delta LVESVI 3 months – baseline, mL/m2

baseline

#CD26+ MNCs / mL blood, #*10E6

8

4

0

C

901

1 week after MI

3 months after MI

20

0

-20

P=0.026, ρ 0.366

-40

4

6

8

10

mncCD26 expression 1 week after MI, MFI

Fig. 1. sCD26 levels are decreased 1 week after MI when compared to baseline (P = 0.001, A). MncCD26 expression however, measured by MFI for CD26 on CD26+ MNCs, is high at 1 week after MI when compared to 3 months (P = 0.015, B). No significant difference in number of CD26+ MNCs is found between the time points (P = 0.124, C). High mncCD26 expression is associated with an unfavorable overall change in cardiac function (D). Data are expressed as median ± interquartile range (IQR, box), maximal/minimal values within 1.5 IQR (whiskers) and outliers (•) or extremes (°). *P b 0.05.

performed using CXP software (Beckman Coulter, The Netherlands). The number of positive cells is expressed as absolute cell number per mL of whole blood, or as percentage of positive cells within a cell fraction. The Mean-Fluorescent Intensity (MFI) is presented for cell populations of interest.

added to the cell suspension. The number of MNCs per 10,000 beads was assessed on a flow cytometer. The migration percentage was calculated from the number of cells migrated to SDF-1α compared to the number of cells migrated in the absence of SDF-1α. As control, we used blood samples obtained from 10 patients with stable coronary artery disease.

2.5. ELISA 2.7. Statistics Plasma soluble CD26 (sCD26) and NT-pro-BNP were measured by use of commercially available ELISA kits (R&D Systems, Inc., Minneapolis, USA and Biomedica, Wien, Austria). 2.6. MNC migration The MNC migration capacity from 10 early statin treated MI patients – randomly selected – at the three different time points was assessed in a transwell system using polycarbonate filters with 5 μm pores (Corning, The Netherlands). Prior to migration, MNCs were incubated for 1 h in RPMI 1640 Glutamax medium supplemented with 10% FBS at 37 °C. One hundred thousand MNCs were applied to the upper well. To determine the effect of CD26 inhibition on the migration of MNCs, cells were pre-treated at room temperature for 15 min with 1 mM sitagliptin (MSD, Haarlem, The Netherlands) in RPMI 1640 medium supplemented with 10% FBS. In the lower well medium with 0 or 200 ng/mL SDF-1α (PeproTech, Rocky Hill, NJ, USA) was added. The cells were allowed to migrate for 3 h at 37 °C. Migration experiments were performed in duplicate. After incubation, migrated cells were collected. Subsequently, 75,000 scarlet fluospheres (15 μm, Invitrogen, Eugene, Oregon, USA) were

Since no statistical differences were found between early placebo and early statin treated patients using the Mann–Whitney U test, we pooled the data from both patient groups to determine CD26 levels and expression in time after MI. Statistical significance was evaluated with the Friedman test for three related samples, Wilcoxon Signed Ranks test for two related samples (Post hoc analysis with Bonferroni correction after Friedman test) and Spearman's rho for correlation calculations using SPSS v16.0 for Windows. Results are expressed as median ± interquartile range. A value of P b 0.05 was considered statistically significant. All reported P values are two-sided. 3. Results 3.1. Patient characteristics and MR imaging The study population consisted of forty-two patients (82% male, median age 57.0±13.5 years). Patient characteristics are shown in Table 1. MR imaging characteristics are shown in Table 2. Both LVESVI and PEA showed a very strong correlation between the three time points. Furthermore, EF was correlated to LVESVI. However, no significant correlation

S. Post et al. / Journal of Molecular and Cellular Cardiology 53 (2012) 899–905

Migration capacity to SDF-1α (%)

A

* 300

B

*

Migration capacity to SDF-1α (%)

902

200

100

1 week after MI

* 400

200

3 months after MI

baseline

D

12

8

P =0.030, ρ -0.347

4 0

200

400

Migration capacity to SDF-1α (%)

Delta LVESVI 3 months – baseline, mL/m2

baseline

CD26+ expression MNC (MFI)

600

0

0

C

- sitagliptin + sitagliptin

1 week after MI

3 months after MI

20

0

P=0.434, ρ 0.280

-20

0

100

200

Migration capacity to SDF-1α, 1 week after MI (%)

Fig. 2. MNCs show a decreased in vitro migration capacity to SDF-1α 1 week after MI (baseline versus 3 months P = 0.024, 1 week versus 3 months P = 0.033, A). CD26 inhibition with sitagliptin resulted in improved in vitro migration one week post MI (P = 0.022, B). MncCD26 expression is negatively associated with MNC migration capacity towards SDF-1α (C). No association is found for overall change in cardiac function and migration capacities towards SDF-1α at 1 week (D). Data are expressed as median ± interquartile range (IQR, box), maximal/minimal values within 1.5 IQR (whiskers) and outliers (•) or extremes (°). *P b 0.05.

was found for the change in LVESVI 3 months−baseline; LVESVI 1 week−baseline when compared to PEA. Percentage enhanced area at 3 months; LVESVI 3 months−baseline and LVESVI 1 week−baseline were therefore chosen for the correlation study. 3.2. Early atorvastatin treatment has no effect on CD26 Early atorvastatin treatment after MI did not show any effect on CD26 cell numbers or mncCD26 expression at baseline, 1 week or 3 months after MI (data not shown). Furthermore, no differences were found in sCD26 levels in plasma at baseline or 1 week after MI. However, we did find modestly elevated sCD26 levels in early statin treated patients at 3 months compared to patients that received statin treatment from day eight after MI (data not shown). Since no differences were found in cardiac function between the groups at all time points data from all MI patients – early and non early statin treated patients – were pooled to study the effect of MI on CD26 and its relation to cardiac function as measured by MRI. 3.3. CD26 and overall cardiac function improvement One week post MI, sCD26 levels in plasma were relatively low compared to baseline (Fig. 1A). Interestingly, mncCD26 expression was relatively high 1 week post MI compared to the expression at 3 months (Fig. 1B), while no differences in the absolute number of CD26 expressing MNCs were found (Fig. 1C). High mncCD26 expression at 1 week post MI was associated with decreased cardiac function improvement — shown by a low delta LVESVI at 3 months compared to baseline (Fig. 1D).

3.4. MNC post MI migration capacity To determine the effect of high surface mncCD26 expression on migration towards SDF-1α, we performed an in vitro transwell migration assay without or with pre-treatment of the MNCs with sitagliptin, a CD26 inhibitor. The number of migrated MNCs towards SDF-1α was decreased when isolated 1 week post MI (Fig. 2A), while inhibition of CD26 resulted in enhanced migration (Fig. 2B). MncCD26 expression correlates negatively with the migration capacity of MNCs to SDF-1α (Fig. 2C). However, no relation was found between MNC migration capacity to SDF-1α at 1 week post MI and overall functional improvement — expressed by a low delta LVESVI at 3 months compared to baseline (Fig. 2D). 3.5. Effects of early cardiac failure on CD26 and migration capacities Soluble CD26 was negatively associated with increased infarct size, as determined by PEA (Fig. 3A). Also early left ventricular failure – shown by a high delta LVESVI at 1 week compared to baseline and high baseline NT-pro-BNP levels – was associated with further reduction of sCD26 (Fig. 3B, C). Thus large infarcts and early deterioration of cardiac function were associated with low sCD26 serum levels at 1 week. No correlation was found for early left ventricular failure – expressed by a high delta LVESVI 1 week vs. baseline – and mncCD26 expression (Fig. 3D). No correlations of baseline sCD26 and mncCD26 expression with infarct size or change in LVESVI were found (data not shown). Furthermore, early left ventricular failure – expressed by a high delta LVESVI 1 week versus baseline – was associated with increased migration at one week post MI (Fig. 3E).

S. Post et al. / Journal of Molecular and Cellular Cardiology 53 (2012) 899–905

A

P=0.045, ρ -0.323

B

20 P=0.004, ρ -0.462

Delta LVESVI 1 week after MI – baseline, mL/m2

PEA, %

40

20

0

-20

0 200

400

0.6

600

Baseline NT-pro-BNP, fmol/mL

C

D

P=0.011, ρ -0.417

1000

500

0.8

1.0

1.2

Delta LVESVI 1 week – baseline, mL/m2

sCD26 ratio: 1 week after MI / baseline

E

0.8

1.0

1.2

sCD26 ratio: 1 week after MI / baseline Delta LVESVI 1 week – baseline, mL/m2

sCD26 1 week after MI, ng/mL

0 0.6

903

20

P=0.086, ρ 0.282

0

-20

-40 4

6

8

10

mncCD26 expression 1 week after MI, MFI

20

0

P=0.045, ρ 0.678

-20

0

100

200

Migration capacity to SDF-1α, 1 week after MI (%) Fig. 3. Large infarctions, measured by PEA, correlate with low sCD26 concentrations 1 week post MI (A). An early unfavorable change in cardiac function, represented by a high delta LVESVI (1 week − baseline) and high NT-pro-BNP, are associated with higher sCD26 down regulation (ratio 1 week/baseline) (B, C). No significant correlation exists between mncCD26 expression at 1 week and early left ventricular malfunctioning (D). Early left ventricular malfunctioning – expressed by a high delta LVESVI – is associated with increased migration capacities towards SDF-1α at 1 week (E).

These associations suggest that large infarctions or early left ventricular function deterioration results in an adapted systemic response to maximize homing to the infarcted myocardium. 4. Discussion Understanding the pathophysiologic responses after MI, its effects on cell trafficking, and identification of factors that influence cell homing and retention are of great importance to improve cell based therapy aiming at cardiac regeneration. In the past years the SDF-1α/CXCR4 axis has gained much attention. This axis was shown to be important for hematopoietic stem cell mobilization and homing [16], HIV infection [10,11] and is a central regulator to guide

cells towards the infarcted myocardium [8]. The SDF-1α/CXCR4 axis is negatively regulated by the dipeptidylpeptidase CD26, which is expressed on the surface of several cell types and can be found in a soluble form in plasma [17–19]. Previous studies suggest that low plasma levels of sCD26 result in increased homing of CXCR4+ cells towards areas with high SDF-1α levels [17,20]. Zaruba and coworkers showed in a murine MI model that systemic CD26 inhibition post MI results in improved homing of CXCR4+ cells towards the infarct area, reduced cardiac remodeling and improved cardiac function [20]. Furthermore, CXCR4 deficiency was shown to cause leukocytosis and to aggravate atherosclerosis in a mouse model [21], which may imply that CD26 inhibition after MI could beneficially affect overall atherosclerosis.

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S. Post et al. / Journal of Molecular and Cellular Cardiology 53 (2012) 899–905

However, another study showed that although MI size was reduced in CXCR4+/− mice, cardiac function was unaffected — suggesting that decreased CXCR4 expression per se does not negatively influence cardiac repair after MI [22]. In patients with Sézary syndrome – a cutaneous T-cell lymphoma – reduced activity of sCD26 was found, suggesting an increased homing capacity of tumor cells (all CD26 negative) towards the high SDF-1α levels in the skin [17]. Here we show that low plasma sCD26 levels are associated with early left ventricular malfunctioning and large MIs. These results suggest that the physiologic response to create favorable circumstances for cell homing to an infarct area depends on the severity of the myocardial damage. Further down regulation of plasma sCD26 may positively influence cell migration to the myocardium by enhancing the SDF-1α homing gradient and improve cardiac function. CD26 inhibition in patients can be achieved by treatment with a CD26 inhibitor such as sitagliptin or vildagliptin, which are currently used as antidiabetic therapies and in a clinical trial aiming at improving cardiac function after MI [23,24]. CD26 is not only involved in cell homing, but also in mobilization of cells from the bone marrow into the circulation. Both G-CSF and GM-CSF, known to be mobilizing factors for progenitor cells from the bone marrow into the circulation and upregulated after MI, induce cellular CD26 expression and activity on CD34+CD38‐ human cord blood cells, decreasing their migration capacities towards SDF-1α present in the bone marrow [25]. Interestingly, we found that 1 week after MI mncCD26 expression is relatively high, while MNC migration towards SDF-1α is decreased at this time point. Furthermore mncCD26 expression is negatively correlated with MNC migration towards SDF-1α. Interestingly, high mncCD26 expression at 1 week after MI is associated with decreased overall recovery of left ventricular function as measured by left ventricular end systolic volume index. Therefore, cellular CD26 expression not only affects the migration of MNCs towards SDF-1α, but these results suggest that it also affects functional improvement after MI. Thus inhibition of CD26 using e.g. sitagliptin may positively influence MNC homing and cardiac function after MI. The presence of the CXCR4 on MNCs is essential for migration towards SDF-1α [26,27]. One week post MI, the number of CXCR4+ cells is reduced, while the expression level of CXCR4, as measured by mean fluorescent intensity (MFI), is not changed (Supplementary Fig. 1) A similar result was also reported by Wojakowski and coworkers [28]. We found no relation with infarct size or cardiac function (data not shown). The combination of high cellular CD26 expression and the lower numbers of CXCR4 bearing cells generates an unfavorable combination for SDF-1α mediated homing. In conclusion, our results suggest that high cellular CD26 expression decreases the migration of MNCs towards SDF-1α and high cellular CD26 expression negatively influences cardiac function post MI. Treating patients shortly post MI with sitagliptin to inhibit CD26 may increase MNC homing to the infarct area and therefore could improve cardiac recovery and repair. Sources of funding Pieter Doevendans was supported by a grant from the Bekalis Foundation, the Wijnand M. Pon Foundation and an unrestricted educational grant by Pfizer. Disclosures None. Acknowledgments We thank the departments of Research and Development of both hospitals for their excellent study support. We also thank Awara Rasul for his excellent analysis of the MR imaging studies.

Appendix A. Supplementary data Supplementary data to this article can be found online at http:// dx.doi.org/10.1016/j.yjmcc.2012.08.026.

References [1] Lopez AD, Mathers CD, Ezzati M, Jamison DT, Murray CJ. Global and regional burden of disease and risk factors, 2001: systematic analysis of population health data. Lancet 2006;367(9524):1747-57. [2] Van de Werf F, Bax J, Betriu A, Blomstrom-Lundqvist C, Crea F, Falk V, et al. Management of acute myocardial infarction in patients presenting with persistent ST-segment elevation: the Task Force on the Management of ST-Segment Elevation Acute Myocardial Infarction of the European Society of Cardiology. Eur Heart J 2008 Dec;29(23):2909-45. [3] Fox KA, Dabbous OH, Goldberg RJ, Pieper KS, Eagle KA, Van de Werf F, et al. Prediction of risk of death and myocardial infarction in the six months after presentation with acute coronary syndrome: prospective multinational observational study (GRACE). BMJ Nov 25 2006;333(7578):1091. [4] Tatsumi T, Ashihara E, Yasui T, Matsunaga S, Kido A, Sasada Y, et al. Intracoronary transplantation of non-expanded peripheral blood-derived mononuclear cells promotes improvement of cardiac function in patients with acute myocardial infarction. Circ J 2007;71(8):1199-207. [5] Martin-Rendon E, Brunskill S, Doree C, Hyde C, Watt S, Mathur A, et al. Stem cell treatment for acute myocardial infarction. Cochrane Database Syst Rev 2008;4: CD006536. [6] Abdel-Latif A, Bolli R, Tleyjeh IM, Montori VM, Perin EC, Hornung CA, et al. Adult bone marrow-derived cells for cardiac repair: a systematic review and meta-analysis. Arch Intern Med 2007 May 28;167(10):989-97. [7] Sun L, Zhang T, Lan X, Du G. Effects of stem cell therapy on left ventricular remodeling after acute myocardial infarction: a meta-analysis. Clin Cardiol May 2010;33(5): 296-302. [8] Smart N, Riley PR. The stem cell movement. Circ Res 2008;102(10):1155-68. [9] Ma J, Ge J, Zhang S, Sun A, Shen J, Chen L, et al. Time course of myocardial stromal cell-derived factor 1 expression and beneficial effects of intravenously administered bone marrow stem cells in rats with experimental myocardial infarction. Basic Res Cardiol 2005;100(3):217-23. [10] Herrera C, Morimoto C, Blanco J, Mallol J, Arenzana F, Lluis C, et al. Comodulation of CXCR4 and CD26 in human lymphocytes. J Biol Chem 2001;276(22):19532-9. [11] Proost P, Struyf S, Schols D, Durinx C, Wuyts A, Lenaerts JP, et al. Processing by CD26/dipeptidyl-peptidase IV reduces the chemotactic and anti-HIV-1 activity of stromal-cell-derived factor-1alpha. FEBS Lett 1998;432(1–2):73-6. [12] van Laake LW, van den Driesche S, Post S, Feijen A, Jansen MA, Driessens MH, et al. Endoglin has a crucial role in blood cell-mediated vascular repair. Circulation 2006;114(21):2288-97. [13] Post S, Smits AM, van den Broek AJ, Sluijter JP, Hoefer IE, Janssen BJ, et al. Impaired recruitment of HHT-1 mononuclear cells to the ischaemic heart is due to an altered CXCR4/CD26 balance. Cardiovasc Res 2010;85(3):494-502. [14] Eefting FD, Cramer MJ, Stella PRS, Rensing BJ, Doevendans PA. Rationale of the REPERATOR study. Neth Heart J 2006;14:95-9. [15] Post S, Post MC, van den Branden BJ, Eefting FD, Goumans MJ, Stella PR, et al. Early statin treatment prior to primary PCI for acute myocardial infarction: REPERATOR, a randomized placebo-controlled pilot trial. Catheter Cardiovasc Interv Mar 14 2012, http://dx.doi.org/10.1002/ccd.23449. [Epub ahead of print]. [16] Broxmeyer HE. Chemokines in hematopoiesis. Curr Opin Hematol 2008;15(1): 49-58. [17] Narducci MG, Scala E, Bresin A, Caprini E, Picchio MC, Remotti D, et al. Skin homing of Sezary cells involves SDF-1-CXCR4 signaling and down-regulation of CD26/dipeptidylpeptidase IV. Blood 2006;107(3):1108-15. [18] Durinx C, Lambeir AM, Bosmans E, Falmagne JB, Berghmans R, Haemers A, et al. Molecular characterization of dipeptidyl peptidase activity in serum: soluble CD26/dipeptidyl peptidase IV is responsible for the release of X-Pro dipeptides. Eur J Biochem 2000;267(17):5608-13. [19] Christopherson KW, Hangoc G, Broxmeyer HE. Cell surface peptidase CD26/dipeptidylpeptidase IV regulates CXCL12/stromal cell-derived factor-1 alpha-mediated chemotaxis of human cord blood CD34+ progenitor cells. J Immunol 2002;169(12):7000-8. [20] Zaruba MM, Theiss HD, Vallaster M, Mehl U, Brunner S, David R, et al. Synergy between CD26/DPP-IV inhibition and G-CSF improves cardiac function after acute myocardial infarction. Cell Stem Cell 2009;4(4):313-23. [21] Zernecke A, Bot I, Djalali-Talab Y, Shagdarsuren E, Bidzhekov K, Meiler S, et al. Protective role of CXC receptor 4/CXC ligand 12 unveils the importance of neutrophils in atherosclerosis. Circ Res 2008 Feb 1;102(2):209-17. [22] Liehn EA, Tuchscheerer N, Kanzler I, Drechsler M, Fraemohs L, Schuh A, et al. Double-edged role of the CXCL12/CXCR4 axis in experimental myocardial infarction. J Am Coll Cardiol 2011 Nov 29;58(23):2415-23. [23] Fisman EZ, Tenenbaum A. A cardiologic approach to non-insulin antidiabetic pharmacotherapy in patients with heart disease. Cardiovasc Diabetol 2009;8(1):38. [24] Theiss HD, Brenner C, Engelmann MG, Zaruba MM, Huber B, Henschel V, et al. Safety and efficacy of SITAgliptin plus GRanulocyte-colony-stimulating factor in patients suffering from Acute Myocardial Infarction (SITAGRAMI-Trial) — rationale, design and first interim analysis. Int J Cardiol Nov 19 2010;145(2):282-4.

S. Post et al. / Journal of Molecular and Cellular Cardiology 53 (2012) 899–905 [25] Christopherson KW, Uralil SE, Porecha NK, Zabriskie RC, Kidd SM, Ramin SM. G-CSF- and GM-CSF-induced upregulation of CD26 peptidase downregulates the functional chemotactic response of CD34+CD38‐human cord blood hematopoietic cells. Exp Hematol 2006;34(8):1060-8. [26] Abbott JD, Huang Y, Liu D, Hickey R, Krause DS, Giordano FJ. Stromal cell-derived factor-1alpha plays a critical role in stem cell recruitment to the heart after myocardial infarction but is not sufficient to induce homing in the absence of injury. Circulation 2004;110(21):3300-5.

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[27] Askari AT, Unzek S, Popovic ZB, Goldman CK, Forudi F, Kiedrowski M, et al. Effect of stromal-cell-derived factor 1 on stem-cell homing and tissue regeneration in ischaemic cardiomyopathy. Lancet 2003;362(9385):697-703. [28] Wojakowski W, Tendera M, Michalowska A, Majka M, Kucia M, Maslankiewicz K, et al. Mobilization of CD34/CXCR4+, CD34/CD117+, c-met+ stem cells, and mononuclear cells expressing early cardiac, muscle, and endothelial markers into peripheral blood in patients with acute myocardial infarction. Circulation 2004;110(20):3213-20.