Coronary collateral growth (CCG) is impaired in metabolic syndrome (MetS). microRNA-145 (miR-145-Adv) delivery to our rat model of metabolic syndrome (JCR) completely restored and neutrophil depletion significantly improved CCG. We determined whether low endogenous levels of miR-145 in MetS allowed for elevated production of 20-hydroxyeicosatetraenoic acid (20-HETE), which in turn, resulted in excessive neutrophil accumulation and endothelial dysfunction leading to impaired CCG. Rats underwent 0-9 days of repetitive ischemia (RI). RI-induced cardiac CYP4F (neutrophil-specific 20-HETE synthase) expression and 20-HETE levels were increased (4-fold) in JCR vs. normal rats. miR-145-Adv and 20-HETE antagonists abolished, and neutrophil depletion (blocking antibodies) reduced (~60%) RI-induced increases in CYP4F expression and 20-HETE production in JCR rats. Impaired CCG in JCR rats (collateral-dependent blood flow using microspheres) was completely restored by 20-HETE antagonists ((collateral-dependent zone)CZ/(normal zone)NZ flow ratio was 0.76±0.07 in JCR+20-SOLA, 0.84±0.05 in JCR+20-HEDGE vs. 0.11±0.02 in JCR vs. 0.84±0.03 in normal rats). In JCR rats, elevated 20-HETE was associated with excessive expression of endothelial adhesion molecules and neutrophil infiltration which were reversed by miR-145-Adv. Endothelium-dependent vasodilation of coronary arteries, eNOS Ser1179 phosphorylation, eNOS-dependent NO.- production and endothelial cell survival were compromised in JCR rats. These parameters of endothelial dysfunction were completely reversed by 20-HETE antagonism or miR-145-Adv delivery, whereas neutrophil depletion resulted in partial reversal (~70%). We conclude that low miR-145 in MetS allows for increased 20-HETE, mainly from neutrophils, which compromises endothelial cell survival and function leading to impaired CCG. 20-HETE antagonists could provide viable therapy for restoration of CCG in MetS.
- endothelial dysfunction
- Copyright © 2016, American Journal of Physiology-Heart and Circulatory Physiology