Endothelial deletion of PKCδ prevents VEGF inhibition and restores blood flow reperfusion in diabetic ischemic limb.

Laura Croteau,Andréanne Guay,Marc-Antoine Despatis,Stéphanie Robillard,Valérie Breton,Étienne Fafard-Couture,Clément Mercier,Pedro Geraldes,Farah Lizotte,Alexandre Nadeau

doi:10.1177/1479164121999033

Abstract

Aims:Peripheral artery disease is a complication of diabetes leading to critical hindlimb ischemia. Diabetes-induced inhibition of VEGF actions is associated with the activation of protein kinase Cδ (PKCδ). We aim to specifically investigate the role of PKCδ in endothelial cell (EC) function and VEGF signaling.Methods:Nondiabetic and diabetic mice, with (ec-Prkcd−/−) or without (ec-Prkcdf/f) endothelial deletion of PKCδ, underwent femoral artery ligation. Blood flow reperfusion was assessed up to 4 weeks post-surgery. Capillary density, EC apoptosis and VEGF signaling were evaluated in the ischemic muscle. Src homology region 2 domain-containing phosphatase-1 (SHP-1) phosphatase activity was assessed in vitro using primary ECs.Results:Ischemic muscle of diabetic ec-Prkcdf/f mice exhibited reduced blood flow reperfusion and capillary density while apoptosis increased as compared to nondiabetic ec-Prkcdf/f mice. In contrast, blood flow reperfusion and capillary density were significantly improved in diabetic ec-Prkcd−/− mice. VEGF signaling pathway was restored in diabetic ec-Prkcd−/− mice. The deletion of PKCδ in ECs prevented diabetes-induced VEGF unresponsiveness through a reduction of SHP-1 phosphatase activity.Conclusions:Our data provide new highlights in mechanisms by which PKCδ activation in EC contributed to poor collateral vessel formation, thus, offering novel therapeutic targets to improve angiogenesis in the diabetic limb.

Highlights

Peripheral artery disease is a direct manifestation of obstructive atherosclerosis characterized by the progressive narrowing of the artery, which gradually reduces blood supply to the limbs causing critical ischemia.[1]
Body weight and fasting blood glucose levels were measured at euthanasia and the deletion of protein kinase Cδ (PKCδ) did not affect both parameters in the context of diabetes (Supplemental Table 2)
We have previously uncovered the involvement of the PKCδ isoform in the inhibition of Vascular endothelial growth factor (VEGF) signaling in the whole ischemic muscle of diabetic mice.[13]

Summary

Introduction

Peripheral artery disease is a direct manifestation of obstructive atherosclerosis characterized by the progressive narrowing of the artery, which gradually reduces blood supply to the limbs causing critical ischemia.[1] Diabetes increases the incidence of PAD and causes 10–16 times higher risk of non-traumatic lower limb amputation, mainly due to insufficient collateral vessel formation.[2] Hyperglycemia has been shown to alter angiogenic processes involving complex interplays between various growth factors and cell types.[3]. Vascular endothelial growth factor (VEGF) plays a fundamental role in the angiogenic process. The identification of the underlying molecular mechanisms involved in the deregulation of VEGF signaling in hyperglycemia has generated further interest

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Conclusion