Abdominal Aortic Endothelial Dysfunction Occurs in Female Mice With Dextran Sodium Sulfate-Induced Chronic Colitis Independently of Reactive Oxygen Species Formation

Genetic background influences arterial vasomotor function in male and female mice

The purpose of this study was to assess the influence of genetic background and sex on nitric oxide (NO)-mediated vasomotor function in arteries from different vascular territories. Vasomotor function was assessed in thoracic aorta, abdominal aorta, carotid arteries, and femoral arteries from the following mouse strains: SJL/J, DBA/2J, NZW/LacJ, and C57BL/6J. Contractile responses were assessed using the α1-adrenergic receptor agonist phenylephrine (PE, 10-9 -10-5  M). Vasorelaxation responses were assessed by examining relaxation to an endothelium-dependent vasodilator acetylcholine (ACh, 10-9 -10-5  M) and an endothelium-independent vasodilator sodium nitroprusside (SNP, 10-9 -10-5  M). To evaluate the role of NO, relaxation responses to ACh and SNP were assessed in the absence or presence of a nitric oxide synthase inhibitor (N omega-nitro-l-arginine methyl ester hydrochloride: 10-4  M). Vasomotor responses to ACh and PE varied across strains and among the arteries tested with some strains exhibiting artery-specific impairment. Results indicated some concentration-response heterogeneity in response to ACh and SNP between vessels from females and males, but no significant differences in responses to PE. Collectively, these findings indicate that vasomotor responses vary by genetic background, sex, and artery type.

Adventitial macrophage accumulation impairs perivascular nerve function in mesenteric arteries with inflammatory bowel disease

Introduction: Inflammatory bowel disease involves aberrant immune responses and is associated with both cardiovascular disease risk and altered intestinal blood flow. However, little is known about how inflammatory bowel disease affects regulation of perivascular nerves that mediate blood flow. Previous work found perivascular nerve function is impaired in mesenteric arteries with Inflammatory bowel disease. The purpose of this study was to determine the mechanism of impaired perivascular nerve function. Methods: RNA sequencing was performed on mesenteric arteries from IL10^-/- mice treated with H. hepaticus to induce disease (inflammatory bowel disease) or left non-gavaged (Control). For all other studies, Control and Inflammatory bowel disease mice received either saline or clodronate liposome injections to study the effect of macrophage depletion. Perivascular nerve function was assessed using pressure myography and electrical field stimulation. Leukocyte populations, and perivascular nerves, and adventitial neurotransmitter receptors were labeled using fluorescent immunolabeling. Results: Inflammatory bowel disease was associated with increases in macrophage-associated gene expression, and immunolabeling showed accumulation of adventitial macrophages. Clodronate liposome injection eliminated adventitial macrophages, which reversed significant attenuation of sensory vasodilation, sympathetic vasoconstriction and sensory inhibition of sympathetic constriction in inflammatory bowel disease. Acetylcholine-mediated dilation was impaired in inflammatory bowel disease and restored after macrophage depletion, but sensory dilation remained nitric oxide independent regardless of disease and/or macrophage presence. Conclusion: Altered neuro-immune signaling between macrophages and perivascular nerves in the arterial adventitia contributes to impaired vasodilation, particularly via dilatory sensory nerves. Targeting the adventitial macrophage population may help preserve intestinal blood flow in Inflammatory bowel disease patients.

Adventitial macrophage accumulation impairs perivascular nerve function in mesenteric arteries with inflammatory bowel disease

Introduction

Inflammatory bowel disease (IBD) involves aberrant immune responses and is associated with both cardiovascular disease risk and altered intestinal blood flow. However, little is known about how IBD affects regulation of perivascular nerves that mediate blood flow. Previous work found perivascular nerve function is impaired in mesenteric arteries with IBD. The purpose of this study was to determine the mechanism of impaired perivascular nerve function.

Methods

RNA sequencing was performed on mesenteric arteries from IL10 ^-/- mice treated with H.hepaticus to induce disease (IBD) or left non-gavaged (Control). For all other studies, Control and IBD mice received either saline or clodronate liposome injections to study the effect of macrophage depletion. Perivascular nerve function was assessed using pressure myography and electrical field stimulation. Fluorescent immunolabeling was used to label leukocyte populations and perivascular nerves.

Results

IBD was associated with increased in macrophage-associated gene expression, and immunolabeling showed accumulation of adventitial macrophages. Clodronate liposome injection eliminated adventitial macrophages, which reversed significant attenuation of sensory vasodilation, sympathetic vasoconstriction and sensory inhibition of sympathetic constriction in IBD. Acetylcholine-mediated dilation was impaired in IBD and restored after macrophage depletion, but sensory dilation remained nitric oxide independent regardless of disease and/or macrophage presence.

Conclusion

Altered neuro-immune signaling between macrophages and perivascular nerves in the arterial adventitia contributes to impaired vasodilation, particularly via dilatory sensory nerves. Targeting the adventitial macrophage population may help preserve intestinal blood flow in IBD patients.

Recovery of Ischemic Limb and Femoral Artery Endothelial Function Are Preserved in Mice with Dextran Sodium Sulfate-Induced Chronic Colitis

Simple Summary

The present study examines the effect of experimental inflammatory bowel disease on femoral artery endothelial function and limb ischemia recovery in female mice using a chronic colitis model induced by dextran sodium sulfate exposure. As expected, plasma levels of proinflammatory cytokines, including interleukin-6, interleukin-17, tumor necrosis factor alpha, and chemokine ligand 1, were significantly increased in the chronic colitis model. However, ROS levels in the ischemic muscle tissues were not significantly increased in mice with colitis as compared to controls. There were no significant changes in endothelium-dependent or -independent vasodilation of femoral artery between the colitis model and the control. Recovery of function and blood flow of the ischemic limb and capillary density in the ischemic muscle were preserved in the colitis model as compared with the control.

Abstract

Inflammatory bowel disease (IBD) produces significant systemic inflammation and increases the risk of endothelial dysfunction and peripheral artery disease. Our recent study demonstrated that abdominal aortic endothelial cell function was impaired selectively in female mice with chronic colitis. This study aimed to test the hypothesis that experimental colitis leads to femoral artery endothelial cell dysfunction and impairs limb ischemia recovery in female mice. An experimental chronic colitis model was created in female C57BL/6 mice with dextran sodium sulfate (DSS) treatment. Unilateral hind limb ischemia was produced by femoral artery ligation. Limb blood perfusion, vascular density, tissue ROS levels, and plasma levels of proinflammatory cytokines were assessed. Femoral artery endothelium-dependent and -independent vasodilation of the contralateral limb were evaluated ex vivo using acetylcholine and nitroglycerin, respectively. As expected, the plasma levels of proinflammatory cytokines, including tumor necrosis factor alpha (TNF-α), interleukin (IL)-6, and IL-17, were significantly increased in the DSS-induced colitis model. However, ROS levels in the ischemic muscle tissues were not significantly increased in colitis model as compared to the controls. There were no significant changes in endothelium-dependent or -independent vasodilation of the femoral artery between colitis model and the control. Recovery of function and blood flow in the ischemic limb and capillary density in the ischemic gastrocnemius muscle were preserved in the colitis model as compared with the control. The data demonstrated that DSS-induced chronic colitis had no significant impact on femoral artery endothelial function or ischemic limb recovery in female mice.