Time course of plasma markers of collagen turnover in patients with acute myocardial infarction

Relationship between the temporal profile of plasma microRNA and left ventricular remodeling in patients after myocardial infarction

BACKGROUND

microRNAs (miRs) are small noncoding RNAs that recognize and bind to mRNAs and inhibit protein translation or degrade mRNA. Studies in animal models have suggested that miRs play a translational or posttranslational regulatory role in myocardial growth, fibrosis, viability, and remodeling. However, whether specific temporal changes in miRs occur in patients during the left ventricular (LV) remodeling process that follows a myocardial infarction (post-MI) remains unknown. The current pilot study tested the hypotheses that plasma miRs could be reliably measured in post-MI patients and that there is a relationship between temporal changes in specific miRs and post-MI LV structural remodeling.

METHODS AND RESULTS

LV end-diastolic volume (echocardiography) and plasma miR were measured in age-matched referent controls (CTLs, n=12) and post-MI patients (n=12) from day 2 through day 90 post-MI. Selected miRs (miR-1, miR-21, miR-29a, miR-133a, and miR-208) were measured using quantitative reverse transcription-polymerase chain reaction and normalized for endogenous small nuclear RNA U6. After MI, LV end-diastolic volume increased progressively compared with CTL; this was accompanied by time-dependent changes in specific miRs. For example, miR-21 initially decreased 2 days post-MI (0.3 ± 0.1-fold versus CTL; P<0.05), increased 5 days post-MI (2 ± 1-fold versus CTL; P<0.05), and returned to CTL values at later post-MI time points. In contrast, miR-29a increased 5 days post-MI (4 ± 1-fold versus CTL; P<0.05) and then decreased to CTL at later time points. miR-208 increased 5 days post-MI (3 ± 1-fold versus CTL; P<0.05) and remained elevated up to 90 days post-MI.

CONCLUSIONS

A time-dependent change in miRs occurred in post-MI patients, including an early and robust increase in miRs that has affected myocardial growth, fibrosis, and viability. Thus, serially profiling miRs in the plasma of post-MI patients may hold both mechanistic and prognostic significance.

Time course of early changes in plasma markers of collagen turnover following percutaneous transluminal coronary angioplasty

INTRODUCTION

Marked changes occur in the collagen framework of the heart following acute ischemia, which is associated with adverse ventricular remodelling. Plasma markers of collagen turnover are useful in the assessment of remodelling and have predictive value, but their exact temporal dynamics following ischemia are unclear.

OBJECTIVE

To characterize the early temporal dynamics of plasma markers of collagen turnover in a human model of coronary artery occlusion.

METHODS

Fourteen patients undergoing elective percutaneous coronary intervention (PCI) to a single coronary artery were recruited in addition to a control group of eight patients undergoing elective diagnostic coronary arteriography. Sequential assessment of plasma levels of procollagen type I carboxyterminal propeptide and C-telopeptide for type I collagen (CITP) as markers of synthesis and degradation, respectively, was performed over a 16 h period.

RESULTS

The ischemic burden in the PCI group was high, with 13 of the 14 patients demonstrating transient ST segment shift or positive troponin. Mean plasma levels of CITP on admission were 3.1 ng⁄mL and 3.0 ng⁄mL in the PCI and control groups, respectively (P value nonsignificant). There was a sequential increase in plasma CITP following PCI, peaking at 4.7 ng⁄mL at 16 h (P<0.01), with no change in the control group. There were no significant changes in plasma levels of procollagen type I carboxyterminal propeptide in either group.

CONCLUSIONS

Plasma levels of CITP demonstrated early temporal dynamics of collagen degradation following transient coronary artery occlusion supporting the use of plasma markers of collagen turnover as an early tool in the assessment of the remodelling process following myocardial ischemia.

Natural history of markers of collagen turnover in patients with early diastolic dysfunction and impact of eplerenone

OBJECTIVES

This study was designed to evaluate the impact of eplerenone on collagen turnover in preserved systolic function heart failure (HFPSF).

BACKGROUND

Despite growing interest in abnormal collagen metabolism as a feature of HFPSF with diastolic dysfunction, the natural history of markers of collagen turnover and the impact of selective aldosterone antagonism on this natural history remains unknown.

METHODS

We evaluated 44 patients with HFPSF, randomly assigned to control (n = 20) or eplerenone 25 mg daily (n = 24) for 6 months, increased to 50 mg daily from 6 to 12 months. Serum markers of collagen turnover and inflammation were analyzed at baseline and at 6 and 12 months and included pro-collagen type-I and -III aminoterminal peptides, matrix metalloproteinase type-2, interleukin-6 and -8, and tumor necrosis factor-alpha. Doppler-echocardiographic assessment of diastolic filling indexes and tissue Doppler analyses were also obtained.

RESULTS

The mean age of the patients was 80 +/- 7.8 years; 46% were male; 64% were receiving an angiotensin-converting enzyme inhibitor, 34% an angiotensin-II receptor blocker, and 68% were receiving beta-blocker therapy. Pro-collagen type-III and -I aminoterminal peptides, matrix metalloproteinase type-2, interleukin-6 and -8, and tumor necrosis factor-alpha increased with time in the control group. Eplerenone treatment had no significant impact on any biomarker at 6 months but attenuated the increase in pro-collagen type-III aminoterminal peptide at 12 months (p = 0.006). Eplerenone therapy was associated with modest effects on diastolic function without any impact on clinical variables or brain natriuretic peptide.

CONCLUSIONS

This study demonstrates progressive increases in markers of collagen turnover and inflammation in HFPSF with diastolic dysfunction. Despite high background utilization of renin-angiotensin-aldosterone modulators, eplerenone therapy prevents a progressive increase in pro-collagen type-III aminoterminal peptide and may have a role in management of this disease. (The Effect of Eplerenone and Atorvastatin on Markers of Collagen Turnover in Diastolic Heart Failure; NCT00505336).

Relation of high concentrations of plasma carboxy-terminal telopeptide of collagen type I with outcome in acute myocardial infarction

Acute myocardial infarction (AMI) is associated with matrix metalloproteinase activation. The plasma concentrations of carboxy-terminal telopeptide of collagen type I (CITP) reflect collagen type I degradation due to matrix metalloproteinase activation. We assessed the role of CITP as an early marker of outcome in AMI. Plasma CITP was measured 72 hours after hospital admission in 432 patients presenting with AMI. The 2 composite end points of the study (death, resuscitated cardiac arrest, recurrent AMI or ischemia, and heart failure or stroke; and death, resuscitated cardiac arrest, or heart failure) and mortality were assessed at 1 year in 4 patient groups stratified by the CITP quartiles. Patients with ST-segment elevation MI represented 75.7% of the population. In-hospital percutaneous coronary intervention was performed in 70.4% of the patients. The mean left ventricular ejection fraction was 53.9 +/- 12.5%. At 1 year of follow-up, high levels of CITP were associated with the occurrence of both composite end points and mortality (p <0.01 for all). Stepwise logistic regression analysis identified CITP as an independent predictor of both composite end points (odds ratio 2.14, 95% confidence interval 1.34 to 3.42, p = 0.001; and odds ratio 3.19, 95% confidence interval 1.50 to 6.81, p = 0.003), along with the Killip class and brain natriuretic peptide levels. In conclusion, high hospital levels of CITP, a marker of collagen degradation and ventricular remodeling, are associated with late mortality and other serious clinical events after AMI.

Serological evidence of early remodeling in high-risk non-ST elevation acute coronary syndromes

INTRODUCTION

Non-ST elevation acute coronary syndrome (ACS) represents a spectrum of risk, with electrocardiographic (ECG) changes and a positive troponin being associated with higher morbidity and mortality. Ischaemia produces alterations in the collagenous component of the heart, even in the absence of myocyte necrosis. Collagen turnover can be assessed biochemically with C-propeptide for type I collagen (PICP) and C-telopeptide for type I collagen (CITP) being markers of collagen synthesis and degradation respectively. Tissue inhibitor of matrix metalloproteinase-1 (TIMP-1) is a marker of inhibition of degradation.

METHODS

Fifty-two patients with non-ST elevation acute ACS were recruited and dichotomised into high- and low-risk groups based on ECG and troponin level. Sequential measurements of plasma PICP, CITP and TIMP-1 were performed over a 48 hour period.

RESULTS

Twenty were classified as low-risk (negative troponin and normal ECG) and 32 as high-risk. PICP was within the normal range at all time points in both groups. However, admission CITP was higher in the high-risk group (3.7 vs. 2.6 ng/ml, p<0.001) and, unlike the low-risk group, demonstrated a further rise over 48 h. Similarly, mean TIMP-1 displayed a sequential change over time in the high-risk group only, and admission level was higher compared to the low-risk group (302 vs. 221 ng/ml, p<0.01).

DISCUSSION

There is serological evidence of time-dependent altered collagen metabolism in high-risk ACS, which is not present in the low-risk group. This may reflect a degree of remodeling and may aid risk stratification of patients presenting with non-ST elevation ACS.

Serological evidence of altered collagen homeostasis reflects early ventricular remodeling following acute myocardial infarction

BACKGROUND

Infarct expansion characterises early ventricular remodeling following myocardial infarction (AMI) and is a product of the balance between collagen degradation and synthesis. Serological markers of collagen turnover may help in predicting those at risk of remodeling. C-propeptide for type-I collagen (PICP) and C-telopeptide for type-I collagen (CITP) are markers of collagen synthesis and degradation, respectively.

METHODS

Fifty-one patients with AMI were recruited and dichotomised by echocardiographic wall motion index (WMI). Sequential measurements of plasma PICP and CITP were correlated to this and other echocardiographic variables of remodeling.

RESULTS

Twenty-three normal WMI, 28 abnormal WMI. Both groups showed increases in PICP and CITP over time. However, mean admission CITP higher in abnormal WMI group, 4.5 vs. 3.1 ng/ml (p<0.05) as was peak, 6.3 vs. 4.8 ng/ml (p<0.05). Conversely, admission PICP was lower in abnormal WMI group 114 vs. 143 ng/ml (p<0.05). Admission CITP correlated with WMI, r=0.53, p<0.001. CITP>3.2 ng/ml (normal mean+2S.D.) had 74% positive predictive value for abnormal WMI, negative predictive value 65%. Admission CITP negatively correlated with mitral deceleration time (Dt), r=-0.38, p=0.01. CITP>3.2 was associated with lower Dt-183 vs. 221 ms, p<0.05.

CONCLUSION

There is serological evidence of sequential increases in both collagen synthesis and degradation following AMI. However, the balance between these differs in patients who undergo remodeling, manifested by abnormal WMI and reduced Dt, compared to those with no evidence. They have relatively increased degradation and reduced synthesis, favouring net collagen breakdown. These changes occur early with evidence of increased breakdown on admission predicting early remodeling and support the role of serological markers to identify patients at risk of this.