Abstract 434: Prolyl 4-Hydroxylase 2 Gene Silencing Attenuates Post-Ischemic Injury and Proinflammatory Chemokine Generation in Murine Hearts
Background: Hypoxia Inducible Factor-1 (HIF-1) activates genes modulating inflammation (e.g., eNOS, iNOS, and HO-1). We recently showed that in vivo silencing of prolyl 4-hydroxylase 2 (P4HA2) activated HIF-1 and significantly attenuated post-ischemic cardiac injury in a murine Langendorff model. We hypothesized that attenuated post-ischemic injury produced via P4HA2 silencing would reduce cardiac chemokine generation (Macrophage Inflammatory Protein-2 [MIP-2], and keratinocyte derived chemokine [KC]) in hearts subjected to ischemia/reperfusion (I/R).
Methods and Results: Adult B6,129 mice received 1) saline alone, 2) P4HA2 siRNA or 3) non-targeting siRNA control (NTSC) IP 24 hrs prior to left coronary artery ligation (30 min) followed by reperfusion (2 hr) in-vivo. Hearts were collected for IS measurement (morphometry of TTC-stained sections) and cardiac chemokine mRNA quantification (QPCR). Myocardial IS (% of risk area; mean ±SE, n=6/group) was reduced by P4HA2 siRNA (14.8 ±1.6%) when compared to saline (44.9 ±1.7%) or NTSC (43.6 ±1.6%, P <0.05). P4HA2 siRNA attenuated post-ischemic MIP-2 and KC mRNA when compared to saline and NTSC (Figure⇓, *P<0.05, **P<0.01). Sham animals (open chest, no I/R) showed no detectable cardiac MIP-2 or KC mRNA.
Conclusion: In vivo HIF-1 activation via P4HA2 gene silencing attenuates infarct size and cardiac inflammatory responses to I/R injury.