Obesity-induced Endothelial Dysfunction is Prevented by Neutrophil Extracellular Trap Inhibition

Abstract

Endothelial dysfunction precedes atherosclerosis and may constitute a critical link between obesity-related inflammation and cardiovascular disease. Neutrophil extracellular traps (NETs) have been shown to promote vascular damage in murine models of autoimmune disease and atherosclerosis. The impact of NETs towards endothelial dysfunction associated with obesity is unknown. Using a diet-induced obesity (DIO) mouse model, this study investigated whether the inhibition or degradation of NETs could reduce the endothelial dysfunction observed in DIO mice. Following induction of DIO, there were elevated plasma concentrations of monocyte chemoattractant protein-1 (MCP-1) and impairment of mesenteric arteriolar vasorelaxation in response to acetylcholine as measured by pressure myography. A marker of NET formation, cathelicidin-related antimicrobial peptide (CRAMP), was markedly increased in mesenteric arterial walls of DIO mice compared to mice on standard chow. Prevention of NET formation with Cl-amidine or dissolution of NETs with DNase restored endothelium-dependent vasodilation to the mesenteric arteries of DIO mice. These findings suggest an instrumental role for NETs in obesity-induced endothelial dysfunction.

Figure 1

Cathelicidin-related antimicrobial peptide (CRAMP) staining of mesenteric arterioles from WT lean and DIO WT mice with Cl-amidine or DNase treatment (n = 8 mice per group). A, B, C, D: Representative photomicrograph of CRAMP staining in cross sections of mesenteric arterioles from WT lean mice (A), DIO WT mice (B), DIO WT mice after Cl-amidine treatment (C), and DIO WT mice after DNase treatment (D). (E) Quantification of CRAMP-positive area per unit medial area. *P < 0.05. **P < 0.01. Scale: 20 μm.

Figure 2

Plasma levels of monocyte chemoattractant protein-1 (MCP-1) and interleukin-6 (IL-6) (n = 8 mice per group). (A) Levels of MCP-1in WT lean and DIO WT mice with or without Cl-amidine treatment. (B) Levels of MCP-1 in WT lean and DIO WT mice with or without DNase treatment. (C) Levels of IL-6 in WT lean and DIO WT mice after Cl-amidine or DNase treatment. (D) Levels of VCAM-1 in WT lean and DIO WT mice with or without DNase treatment. *P < 0.05. **P < 0.01.

Figure 3

Vasoconstriction and vasorelaxation responses of mesenteric arterioles from control WT lean mice or diet-induced obese (DIO) mice with or without Cl-amidine treatment (n = 8 mice per group). (A) Concentration response to norepinephrine (NE). (B) Concentration response to sodium nitroprusside (SNP). (C) Concentration response to acetylcholine (Ach). (D) Concentration response to Ach after preincubation in L-NAME. *P < 0.01.

Figure 4

Vasoconstriction and vasorelaxation responses of mesenteric arterioles from control WT lean mice or diet-induced obese (DIO) mice with or without DNase treatment (n = 8 mice per group). (A) Concentration response to norepinephrine (NE). (B) Concentration response to sodium nitroprusside (SNP). C: Concentration response to acetylcholine (Ach). (D) Concentration response to Ach after preincubation in L-NAME. *P < 0.01.