Beneficial effects of a novel ultrapotent poly(ADP-ribose) polymerase inhibitor in murine models of heart failure

Abstract

Overactivation of the nuclear enzyme poly(ADP-ribose) polymerase (PARP) contributes to the development of cell dysfunction and tissue injury in various pathophysiological conditions associated with oxidative and nitrosative stress, including myocardial reperfusion injury, heart transplantation, diabetic cardiomyopathy and chronic heart failure. In recent studies, we have demonstrated the beneficial effects of a novel ultrapotent PARP inhibitor, INO-1001, on cardiac and endothelial dysfunction and remodeling in rat model of advanced aging-associated chronic heart failure and in a mouse model of heart failure induced by aortic banding. In the current study, we have investigated the effect of INO-1001 on the development of heart failure induced by permanent ligation of the left anterior descending coronary artery, heart failure induced by doxorubicin and acute myocardial dysfunction induced by bacterial endotoxin. In the coronary ligation model, a significantly depressed left ventricular performance and impaired vascular relaxation of aortic rings were found, and PARP inhibition significantly improved both cardiac function and vascular relaxation. In the doxorubicin model, a single injection of doxorubicin induced high mortality and a significant decrease in left ventricular systolic pressure, +dP/dt, -dP/dt, stroke volume, stroke work, ejection fraction and cardiac output. Treatment with the PARP inhibitor reduced doxorubicin-induced mortality and markedly improved cardiac function. PARP inhibition did not interfere with doxorubicin's antitumor effect. In the endotoxin model of cardiac dysfunction, PARP inhibition attenuated the suppression of myocardial contractility elicited by endotoxin. The current data strengthen the view that PARP inhibition may represent an effective approach for the experimental therapy of various forms of acute and chronic heart failure.

Figure 1

Effect of pharmacological inhibition of PARP on survival in a rat model of chronic heart failure (CHF). Top panel demonstrates mortality prior to randomization of the animals to vehicle and INO-1001 treated groups (n=86 animals). Bottom panel considers surviving animals (n=34) at time of randomization as 100% and shows the effect of INO-1001 on the subsequent mortality.

Figure 2

Effect of CHF and INO-1001 on left ventricular systolic pressure (LVSP), left ventricular end diastolic pressure (LVEDP), left ventricular +dP/dt, left ventricular −dp/dt in rats. S, sham; CHF, chronic heart failure; S + INO-1001 sham treated with INO-1001 (for 10 weeks); CHF + INO-10001, chronic heart failure treated with PJ34 (for 10 weeks). Results are mean ± SEM of 8–10 experiments in each group. *P<0.05 vs. S; ^#P<0.05 vs. CHF.

Figure 3

Effect of pharmacological inhibition of PARP on cardiac remodeling and lung weight in rat model of chronic heart failure (CHF) induced by permanent ligation of left anterior descending (LAD) coronary artery. Left ventricular (LVW), right ventricular (RVW), left atrial (LAW), right atrial (RAW) and lung (LungW) weights in sham (S), INO-1001-treated (for 10 weeks) sham (S + INO-1001), chronic heart failure (CHF) and INO-1001-treated (for 10 weeks) chronic heart failure (CHF + INO-1001) rats. Results are mean ± SEM of 8–10 experiments in each group. The weight of each cavity and lung was normalized to the length of the right tibia. *P<0.05 vs. S; ^#P<0.05 vs. CHF.

Figure 4

Effect of pharmacological inhibition of PARP on endothelium-dependent and endothelium-independent relaxations of rat thoracic aortae ex vivo. Data shown represent sham (S), INO-1001-treated (for 10 weeks) sham (S + INO-1001), chronic heart failure (CHF) and INO-1001-treated (for 10 weeks) chronic heart failure (CHF + INO-1001) aortic relaxant responses to acetylcholine (top) and sodium nitroprusside (bottom) in rings precontracted with epinephrine. Middle panel shows that the contractile ability of the rings was not affected by CHF or PARP inhibition. Results are mean ± SEM of 8–10 experiments in each group. *P<0.05 vs. S; ^#P<0.05 vs. CHF.

Figure 5

Pharmacological inhibition of PARP improves doxorubicin (DOX)-induced left ventricular dysfunction. Representative PV loops (top part) and left ventricular pressure signal (bottom part) from control, DOX and DOX + INO-1001 treated mice. Please note that the rightward shift of PV loops in doxorubicin treated animals, the decrease of maximal left ventricular pressure, and +dP/dt indicate depressed cardiac contractility. INO-1001 improves baseline contractile function.

Figure 6

Pharmacological inhibition of PARP improves doxorubicin (DOX)-induced cardiac dysfunction. Effect of DOX and INO-1001 on left ventricular systolic pressure (LVSP), left ventricular end diastolic pressure (LVEDP), left ventricular +dP/dt, left ventricular −dP/dt, stroke volume, stroke work, ejection fraction, mean blood pressure (mean BP), cardiac output and hear rate in BALB/c mice. CO, control; DOX, doxorubicin treated (a single dose of 25 mg/kg); CO + INO-1001, control treated with INO-1001 (3 mg/kg/day s.c.); DOX + INO-1001, doxorubicin (a single dose of 25 mg/kg) and INO-1001 (3 mg/kg/day s.c.) treated. Hemodynamic parameters were measured 5 days after DOX administration. Results are mean ± SEM of 7–10 experiments in each group. *P<0.05 vs. CO; ^#P<0.05 vs. DOX.

Figure 7

Pharmacological inhibition of PARP with INO-1001 improves survival of mice treated with DOX. Effects of INO-1001 on survival in a DOX-induced acute (A) or chronic (B) heart failure models in mice. (A) Effect of various doses of INO-1001 (0.03, 0.3, and 3 mg/kg/day s.c.) on DOX-induced mortality (25 mg/kg IP) in mice. (B) Effect of various doses of INO-1001 (0.03, 0.3, and 3 mg/kg/day s.c.) on DOX-induced chronic mortality (3 doses of 9 mg/kg IP every 10 days) in mice. Treatment with INO-1001 (3 mg/kg) significantly decreased the DOX-induced mortality.

Figure 8

Effects of INO-1001 on mouse breast carcinoma growth and antineoplastic effect of DOX. CO, controls; CO + INO-1001, control treated with INO-1001 (3 mg/kg/day s.c. minipump); DOX, DOX-treated (twice 4 mg/kg/week PO); DOX + INO-1001, treated with DOX (twice 4 mg/kg/week) and INO-1001 (3 mg/kg/day s.c. minipump). Tumor growth was individually followed in all mice, and tumor diameters (x, y, and z) were measured twice a week after initiation of treatments. Tumor size was calculated in mm³ and expressed as percentage of increase over time compared with initial size at start of treatment (day 0). Results are mean ± SEM of 10 mice in each group. *P<0.05 vs CO.

Figure 9

Pharmacological inhibition of PARP with INO-1001 (10 mg/kg i.v.) improves endotoxin (LPS 15 mg/kg i.v.)-induced acute cardiac dysfunction. Results are mean ± SEM of 9 experiments in each group. *P<0.05 vs. baseline; ^#P<0.05 vs. LPS.