Rapamycin Alters MicroRNA Signature Profile in Diabetic Rabbit following Myocardial Ischemia Reperfusion Injury: A Preclinical Approach for Cardioprotection.

Background Myocardial ischemia reperfusion (I/R) injury associated with cardiovascular risk factors and comorbidities, including Diabetes (DM), is a major complication for development of heart failure. Mammalian target of Rapamycin (mTOR) is robustly active in DM and further exacerbated during I/R. mTOR inhibition with rapamycin at reperfusion preserves cardiac function with reduction of myocardial infarction in diabetic mice. Recent advances in non‐coding RNA analysis demonstrates microRNA (miR) plays an important role in cardiovascular diseases. We examined the effect of rapamycin treatment at the onset of reperfusion in a conscious diabetic rabbit model of I/R and identified differentially regulated miRs. Methods and Results To induce diabetes, alloxan monohydrate (125 mg/kg, i.v.) was administered in New Zealand male rabbits (n=26; average 3 kg, 4 month old). Blood glucose levels increased to 345±66 mg/dL (n=10) following 2 weeks of alloxan administration. The animals were categorized to three groups: Diabetes (DM), Diabetes subjected to I/R (DM+I/R) and Diabetes underwent I/R and treated with Rapamycin (DM+I/R+Rapa). Post 7 days of implantation of balloon occluders on the top of the coronary artery, the conscious rabbits were subjected to 45‐min ischemia and 3 days of reperfusion by inflating/deflating the balloon. Rapamycin (0.25 mg/kg, i.v.) or DMSO (vehicle) was infused 5 min before reperfusion. Plasma was collected at baseline, 1, 2, 4 and 24 hours during the reperfusion and cardiac Troponin I (cTnI) release was measured by ELISA. The results show that rapamycin significantly reduced myocardial infarction in DM rabbits following I/R (Figure A) as assessed by triphenyltetrazolium chloride staining. Rapamycin also reduced cTnI at 1 hr and 2 hr of reperfusion as compared to vehicle alone (Figure B). RNA isolated from risk area of left ventricle heart tissue from different groups (n=3) was subjected to miRNA‐Array analysis using μParaflo ® Microfluidic Biochip Technology (Figure C). The results show 34 out of 761 miRs were differentially regulated with Rapamycin treatment (p<0.01) (Figure D). Enrichment Analysis and Annotation of selected miRs were performed using miEAA and DAVID tools to identify potential targets and its interaction with mTOR signaling pathway. Conclusion This Preclinical translational study demonstrates that rapamycin could be a promising drug in attenuation of reperfusion injury in diabetic patients following acute MI by altering novel miRs. Support or Funding Information NIH RO1HL134366 (AD & RCK) & CCTR Endowment Fund UL1RR031990 (AD) This abstract is from the Experimental Biology 2018 Meeting. There is no full text article associated with this abstract published in The FASEB Journal .