Abstract 11644: The Role of Neutrophil Extracellular Traps in Models of Diabetic Vascular Dysfunction

Aim: NETosis is a type of neutrophil cell death that results in the release of pro-inflammatory neutrophil extracellular traps (NETs). While NETs contribute to some diabetes-associated complications such as dysfunctional wound healing, their potential role in diabetic vascular dysfunction has not been studied. To investigate this possibility, we utilized knockout mice ( Elane -/- and Pad4 -/- ) deficient in NETosis through loss of neutrophil elastase and peptidylarginine deiminase 4, respectively. Methods and Results: Akita mice develop hypoinsulinemia and hyperglycemia by 4 weeks of age. Akita mice were crossed separately with Elane -/- and Pad4 -/- mice to generate NETosis-deficient diabetic mice. Endothelium-dependent vasodilation was assessed in the aortae of the following strains by wire myography (n=10-15/group): wild-type (WT), Akita, Akita- Elane -/- , and Akita- Pad4 -/- . By 24 weeks of age, Akita mice demonstrated consistent impairment of acetylcholine-mediated relaxation (Akita E max =54.1% ± 1.8 and WT=80.6% ± 1.8; p<0.0001). As compared with Akita mice, both Akita- Elane -/- mice (E max =75.1% ± 1.7; p<0.0001) and Akita- Pad4 -/- mice (E max =70.2% ± 1.5; p<0.0001) demonstrated superior relaxation. Furthermore, transfer of neutrophils from aged Akita mice into young WT mice rapidly triggered impaired acetylcholine-mediated relaxation (p<0.0001). Prostanoid metabolites were measured in aortae of 24-week-old mice. TXB 2 (a surrogate for TXA 2 ) was 5-fold higher in both intact and denuded aortae of Akita mice as compared with WT mice (p<0.01); Akita- Elane -/- and Akita- Pad4 -/- mice had TXB 2 levels near WT. Interestingly, 15-deoxy-Δ12,14-PGJ 2 (a dehydration product of PGD 2 and potent PPARγ agonist) was upregulated 10-fold (p<0.001) in Akita endothelium, suggesting an attempted compensatory mechanism. Conclusion: Inhibition of NETosis largely prevented the development of vascular dysfunction in diabetic mice. Thromboxane was strongly upregulated in the vessel walls of NETosis-competent diabetic mice suggesting a role for neutrophils in driving the production of this vasoconstrictive and atherogenic prostanoid. NETosis may represent a novel target for prevention of diabetic complications including vascular dysfunction.