Nourin-Associated miRNAs: Novel Inflammatory Monitoring Markers for Cyclocreatine Phosphate Therapy in Heart Failure.

BACKGROUND

Cyclocreatine phosphate (CCrP) is a potent bioenergetic cardioprotective compound known to preserve high levels of cellular adenosine triphosphate during ischemia. Using the standard Isoproterenol (ISO) rat model of heart failure (HF), we recently demonstrated that the administration of CCrP prevented the development of HF by markedly reducing cardiac remodeling (fibrosis and collagen deposition) and maintaining normal ejection fraction and heart weight, as well as physical activity. The novel inflammatory mediator, Nourin is a 3-KDa formyl peptide rapidly released by ischemic myocardium and is associated with post-ischemic cardiac inflammation. We reported that the Nourin-associated (marker of cell damage) and (marker of inflammation) are significantly upregulated in unstable angina patients and patients with acute myocardial infarction, but not in healthy subjects.

OBJECTIVES

To test the hypothesis that Nourin-associated and are upregulated in ISO-induced "HF rats" and that the administration of CCrP prevents myocardial injury (MI) and reduces Nourin gene expression in "non-HF rats".

METHODS

25 male Wistar rats (180-220 g) were used: ISO/saline ( = 6), ISO/CCrP (0.8 g/kg/day) ( = 5), control/saline ( = 5), and control/CCrP (0.8 g/kg/day) ( = 4). In a limited study, CCrP at a lower dose of 0.4 g/kg/day ( = 3) and a higher dose of 1.2 g/kg/day ( = 2) were also tested. The Rats were injected SC with ISO for two consecutive days at doses of 85 and 170 mg/kg/day, respectively, then allowed to survive for an additional two weeks. CCrP and saline were injected IP (1 mL) 24 h and 1 h before first ISO administration, then daily for two weeks. Serum CK-MB (U/L) was measured 24 h after the second ISO injection to confirm myocardial injury. After 14 days, gene expression levels of and were measured in serum samples using quantitative real-time PCR (qPCR).

RESULTS

While high levels of CK-MB were detected after 24 h in the ISO/saline rats indicative of MI, the ISO/CCrP rats showed normal CK-MB levels, supporting prevention of MI by CCrP. After 14 days, gene expression profiles showed significant upregulation of and by 8.6-fold and 8.7-fold increase, respectively, in the ISO/saline rats, "HF rats," compared to the control/saline group. On the contrary, CCrP treatment at 0.8 g/kg/day markedly reduced gene expression of miR-137 by 75% and of by 44% in the ISO/CCrP rats, "non-HF rats," compared to the ISO/Saline rats, "HF rats." Additionally, healthy rats treated with CCrP for 14 days showed no toxicity in heart, liver, and renal function.

CONCLUSIONS

Results suggest a role of Nourin-associated and in the pathogenesis of HF and that CCrP treatment prevented ischemic injury in "non-HF rats" and significantly reduced Nourin gene expression levels in a dose-response manner. The Nourin gene-based mRNAs may, therefore, potentially be used as monitoring markers of drug therapy response in HF, and CCrP-as a novel preventive therapy of HF due to ischemia.