Inhibition of dipeptidyl peptidase-IV enzyme activity protects against myocardial ischemia-reperfusion injury in rats

Background: We investigated whether attenuating dipeptidyl peptidase-IV (DPP4) enzyme activity protected rat heart from ischemia-reperfusion (IR) injury (40-min left anterior descending coronary artery ligation followed by 72 h reperfusion). Methods and results: Adult male Fischer 344 rats (n = 24) were equally divided into sham-control (WT-SC), WT-IR, and WT-IR-Sita (oral sitagliptin 400 mg/kg/day for 3 days) groups, whereas adult male DPP4-deficiency (DPP4(D)) rats (n = 16) were equally divided into DPP4(D)-SC and DPP4(D)-IR groups. Animals were sacrificed at 72 h after reperfusion with collection of heart specimens. Infarct area (H&E), collagen deposition (Sirius-red stain), fibrotic area (Masson's trichrome), and fluorescent-ROS intensity (H(2)DCFDA-labeling myocardium) of left ventricle were significantly higher in WT-IR than those in other groups, significantly higher in WT-IR-Sita and DPP4D-IR groups than in WT-SC and DPP4D-SC groups (all p < 0.001), but there was no difference between the latter two groups. Protein expressions of oxidative stress (oxidized protein), reactive oxygen species (NOX-1, NOX-2), inflammation (TNF-alpha, NF-kappa B, MMP-9, VCAM-1), apoptosis (mitochondrial Bax, cleaved caspase-3 and PARP), myocardial damage markers (cytosolic cytochrome-C,gamma-H2AX), and number of inflammatory cells (CD14+, CD68+, CD40+ cells) showed a pattern identical to that of histological changes among all groups (all p < 0.005), whereas markers of anti-apoptosis (Bcl-2) and mitochondrial integrity (mitochondrial cytochrome-C) as well as left ventricular ejection fraction showed an opposite pattern (all p < 0.001). Protein expressions of anti-oxidants (HO-1, NQO-1), angiogenesis factors (SDF-1 alpha, CXCR4), and glycogen-like-peptide-1-receptor were significantly higher inWT-IR-Sita and DPP4D-IR than those in other groups (all p < 0.001). Conclusion: Abrogation of DPP4 activity protects against myocardial IR injury and preserved heart function.