Acute coronary syndrome (ACS) including myocardial infarction with or without ST-elevation (STEMI and NSTEMI) and unstable angina pectoris are major causes of morbidity and mortality worldwide [
ACS is now recognized as the net result of a complex event cascade in which thrombotic and inflammatory processes interact and ultimately lead to an atherosclerotic plaque with subsequent destabilization and rupture [
The main aim of the present study was to explore and compare the time profile of circulating PTX3 levels to PTX3 mRNA levels in whole blood (circulating leukocytes) in patients with stable angina pectoris (AP) and acute ST-elevation infarction (AMI), all undergoing successful revascularization with PCI and stent implantation. By investigating both AMI and AP patients we wanted to explore a potential effect of the PCI procedure per se on PTX3 release. Relationship between circulating PTX3 levels and the degree of myocardial necrosis and leukocyte count were further assessed.
Patients between 30 and 75 years, both gender, with AMI (
Blood samples were collected by standard venipuncture immediately before PCI in the AP group and after 3 hours, 12 hours, and 1, 3, 5, 7, and 14 days in both groups. All samples from day 1 and further on were obtained in fasting condition and before intake of any medication. Routine analysis was performed by conventional methods. EDTA-plasma was prepared by centrifugation within 1 hour at 2500 ×g for 20 min at 4°C and stored at −80°C until analysed.
Commercial Enzyme Linked Immunosorbent Assays (ELISA) (R&D Systems, Abingdon, Oxon, UK) were used to determine circulating PTX3 levels. Total RNA was extracted from PAXgene Blood RNA tubes by using the PAXgene Blood RNA Kit (PreAnalytix, Qiagen GmbH, Germany), including an extra cleaning step (Rneasy MinElute Cleanup Kit, Qiagen). A total of 100 ng RNA (range 200–800 ng/
Troponin T (reference value < 0.03
Cardiac magnetic resonance imaging using a 1,5 T whole body scanner (Philips Intera, Best, The Netherlands) was performed after 6 weeks in the AMI group. Left ventricular volume and ejection fraction were calculated on basis of short axis images. Gadolinium late contrast enhancement technique was used to determine infarct size.
Demographic variables are given as proportions or medians (25, 75 quartiles). Nonparametric statistics were used throughout as PTX3 levels were not normally distributed. Medians and 25 and 75 quartiles are given if not otherwise stated. The Mann-Whitney test was used for group comparisons of continuous data. Friedman test was used for analyses of overall change within the groups, and the Wilcoxon test was used for analyses of difference between time points within a group when appropriate. Spearman’s rho was calculated for correlation analysis. Level of significance was set to
Baseline characteristics of the study populations did not differ between the AMI and AP groups, except from higher rate of previous PCI in the AP group (
Baseline characteristics of the study populations.
AMI group ( |
AP group ( | |
---|---|---|
Age, years | 59.5 (54, 67) | 63.5 (54, 71) |
Female gender ( |
5 | 1 |
Hypertension ( |
7 | 4 |
Diabetes ( |
2 | 2 |
Smokers ( |
7 | 2 |
Previous AMI ( |
0 | 2 |
Previous PCI ( |
0 | 4 |
Previous ACB ( |
0 | 2 |
SBP (mmHg) | 140 (120, 154) | 137 (128, 146) |
DBP (mmHg) | 85 (81, 98) | 85 (75, 100) |
TnT max. (ng/L) | 3.5 (2.0, 5.7) | |
Infarct size (MRI) (%) | 6.6 (3.5, 10.7) | |
EF (MRI) (%) | 57.5 (53.3, 66.3) | |
Symptom debut to PCI (min) | 145 (95, 410) | |
Leukocyte count at 12 h | 9.0 (7.8, 10.4) | 7.6 (5.6, 8.2) |
Medication at discharge | ||
Aspirin ( |
20 | 10 |
Clopidogrel ( |
20 | 9 |
ACE-I/AII antagonist ( |
11 | 2 |
|
18 | 6 |
Statin ( |
20 | 10 |
Values are given as proportions or medians (25, 75 percentiles).
ACE-I: angiotensin-converting enzyme inhibitor. AII antagonist: angiotensin II receptor antagonist.
DBP: diastolic blood pressure. EF: ejection fraction. PCI: percutaneous coronary intervention. SBP: systolic blood pressure. TnT: Troponin T.
PTX3 levels at 3 and 12 hours were significantly higher in the AMI group compared to the AP group (2.36 versus 1.37 ng/mL,
The time profile of circulating PTX3 levels. BL: baseline; †
Within the AMI group, an overall change in circulating PTX3 levels was observed (
Within the AP group, an overall change in circulating PTX3 levels was also observed (
No significant correlations at different time points between circulating PTX3 levels and degree of myocardial necrosis measured by TnT or infarct size measured by MRI were obtained (Table
Correlations between circulating PTX3 levels and infarct size.
TnT max. | MRI | |||
---|---|---|---|---|
Correlation coefficient1 |
|
Correlation coefficient |
|
|
PTX3 | ||||
3 h | −0.364 | 0.137 | 0.102 | 0.718 |
12 h | −0.158 | 0.519 | −0.031 | 0.910 |
Day 1 | 0.093 | 0.722 | −0.116 | 0.680 |
Day 3 | −0.138 | 0.586 | −0.339 | 0.200 |
Day 5 | 0.238 | 0.324 | 0.179 | 0.507 |
Day 7 | −0.081 | 0.751 | −0.002 | 0.994 |
Day 14 | −0.237 | 0.344 | −0.223 | 0.406 |
MRI: magnetic resonance imaging; TnT: Troponin T.
Circulating PTX3 levels did not correlate with leukocyte count, except for a negative correlation at day 1 in the AP group (
The PTX3 mRNA levels were significantly lower in the AMI group compared to the AP group at day 1 (
Within the AMI group, PTX3 mRNA levels increased from 3 hours to days 7 and 14 (
(a) Gene expression of PTX3 in circulating leukocytes relative to 3 hours’ levels in the AMI group. (b) Gene expression of PTX3 in circulating leukocytes relative to baseline levels in the AP group.
Within the AP group, PTX3 mRNA levels were reduced from baseline to 3 hours, 12 hours, and day 1 (
No significant correlations were found between circulating PTX3 levels and PTX3 mRNA levels at any time point in either of the groups (data not shown).
The main findings of the study were as follows: (1) circulating PTX3 levels were significantly higher in the AMI group compared to the AP group shortly after PCI, being significantly reduced after 12 hours, (2) circulating PTX3 levels did not correlate to infarct size nor to leukocyte count, and (3) in both groups the genetic expression of PTX3 showed an inverse pattern compared to the circulating levels in a negative feedback manner.
Higher circulating PTX3 levels in AMI patients compared with those in the AP patients short time after PCI indicate that the myocardial infarction per se somehow influences PTX3 levels. As blood samples before PCI were not available in this group, we can only speculate regarding these levels. The possibility that pre-PCI levels would have been even higher might though be indicated. Newly ischemic situations have previously been reported to associate with high PTX3 levels [
In the AP group, limited but statistically significant changes in PTX3 levels from baseline (before PCI) to 3 hours were observed. We suggest that this rise in circulating PTX3 might be related to the PCI procedure per se. This has to be further explored.
Although obviously influenced by the AMI per se, levels of circulating PTX3 did not correlate neither to size of infarction nor to leukocyte count. As to the first, the mean size of myocardial damage was relatively modest in our AMI group, which may influence the result. Lack of correlation between circulating PTX3 levels and infarct size has, however, also been reported elsewhere [
The lack of correlation between circulating PTX3 levels and leukocyte count may indicate that other regulatory mechanisms for PTX3 than the quantitative amount of leukocytes are of importance. It might be that a graded PTX3 release from the granules of neutrophile granulocytes, independent of total leukocyte count, plays a role. Another possibility is release of PTX3 from other cell types than leucocytes, like ischemic cardiomyocytes or activated endothelial cells. The possibility that leucocyte count at 12 h is too late to catch a correlation between quantitative leukocyte count and the immediate secretion of circulating PTX3 during AMI should also be noted.
The genetic expression of PTX3 was upregulated after one week in the AMI group and reduced at 3 hours after PCI in the AP group. The genetic expression profiles of PTX3 seen in both groups might be a compensatory response to the fluctuations seen in the circulating levels in a negative feedback manner. The genetic expression in leukocytes may reflect the amount of circulating PTX3 released by leukocytes. However, PTX3 during an AMI is probably released by both leukocytes and other cells, like activated endothelial cells and injured cardiomyocytes [
The small sample size is a limitation of the study. Strength of the study is the experimental model of studying regulatory mechanisms by comparing circulating PTX3 levels to genetic PTX3 mRNA expression in circulating leukocytes. Although knowledge about circulating PTX3 levels during acute myocardial infarctions has increased lately, data on protein levels in relation to the genetic mRNA levels have until now been scarce.
Elevated circulating PTX3 levels shortly after PCI in AMI patients compared to AP patients indicate that the myocardial infarction per se influences PTX3, although the levels were not correlated to infarct size. The genetic expression of PTX3 in circulating leukocytes showed an inverse pattern, probably compensatory to the fluctuations in the circulating protein levels. The implication of these findings with respect to prognosis in patients with CAD remains to be explored.
The authors declare that there is no conflict of interests regarding the publication of this paper.
The authors thank Haakon K. Grøgaard and Torstein Jensen for taking part in the inclusion of patients. The work was supported by Stein Erik Hagen Foundation for Clinical Heart Research, Oslo, Norway.