Neutrophil microvesicles drive atherosclerosis by delivering miR-155 to atheroprone endothelium.

Neutrophils are implicated in the pathogenesis of atherosclerosis but are seldom detected in atherosclerotic plaques. We investigated whether neutrophil-derived microvesicles may influence arterial pathophysiology. Here we report that levels of circulating neutrophil microvesicles are enhanced by exposure to a high fat diet, a known risk factor for atherosclerosis. Neutrophil microvesicles accumulate at disease-prone regions of arteries exposed to disturbed flow patterns, and promote vascular inflammation and atherosclerosis in a murine model. Using cultured endothelial cells exposed to disturbed flow, we demonstrate that neutrophil microvesicles promote inflammatory gene expression by delivering miR-155, enhancing NF-κB activation. Similarly, neutrophil microvesicles increase miR-155 and enhance NF-κB at disease-prone sites of disturbed flow in vivo. Enhancement of atherosclerotic plaque formation and increase in macrophage content by neutrophil microvesicles is dependent on miR-155. We conclude that neutrophils contribute to vascular inflammation and atherogenesis through delivery of microvesicles carrying miR-155 to disease-prone regions.

Angiopoietin-1 enhances neutrophil chemotaxis in vitro and migration in vivo through interaction with CD18 and release of CCL4.

Angiopoietins are a family of growth factors that are ligands for the tyrosine kinase receptor, Tie2. Angiopoietin 1 (Ang-1) is agonistic for Tie2, plays a key role in blood vessel maturation and stability and has been shown to possess anti-inflammatory properties. However, Tie2 expression has been demonstrated on human neutrophils and the observation that neutrophils migrate in response to Ang-1 in vitro has confounded research into its exact role in inflammation as well as its potential use as a therapeutic agent. We used a mouse model of peritoneal neutrophilic inflammation to determine if Ang-1 could stimulate neutrophil migration in vivo. Tie2 expression was demonstrated on mouse neutrophils. In addition, recombinant human Ang-1 induced significant chemotaxis of isolated mouse neutrophils in a Tie2- and CD18-dependent manner. Subsequently, co-immunoprecipitation of Ang-1 and CD18 demonstrated their interaction. Intraperitoneal injection of an engineered angiopoietin-1, MAT.Ang-1, induced significant neutrophil migration into the peritoneum and a significant increase in the levels of CCL4 in peritoneal lavage fluid. Depletion of resident peritoneal macrophages prior to, or concomitant injections of an anti-CCL4 antibody with MAT.Ang-1 resulted in a significant reduction in neutrophil recruitment. These data indicate a pro-inflammatory role for Ang-1 with respect to neutrophil recruitment.

Neutrophil elastase promotes interleukin-1ß secretion from human coronary endothelium.

The endothelium is critically involved in the pathogenesis of atherosclerosis by producing pro-inflammatory mediators, including IL-1ß. Coronary arteries from patients with ischemic heart disease express large amounts of IL-1ß in the endothelium. However, the mechanism by which endothelial cells (ECs) release IL-1ß remains to be elucidated. We investigated neutrophil elastase (NE), a potent serine protease detected in vulnerable areas of human carotid plaques, as a potential "trigger" for IL-1ß processing and release. This study tested the hypothesis that NE potentiates the processing and release of IL-1ß from human coronary endothelium. We found that NE cleaves the pro-isoform of IL-1ß in ECs and causes significant secretion of bioactive IL-1ß via extracellular vesicles. This release was attenuated significantly by inhibition of neutrophil elastase but not caspase-1. Transient increases in intracellular Ca(2+) levels were observed prior to secretion. Inside ECs, and after NE treatment only, IL-1ß was detected within LAMP-1-positive multivesicular bodies. The released vesicles contained bioactive IL-1ß. In vivo, in experimental atherosclerosis, NE was detected in mature atherosclerotic plaques, predominantly in the endothelium, alongside IL-1ß. This study reveals a novel mechanistic link between NE expression in atherosclerotic plaques and concomitant pro-inflammatory bioactive IL-1ß secretion from ECs. This could reveal additional potential anti-IL-1ß therapeutic targets and provide further insights into the inflammatory process by which vascular disease develops.

Construct validity of the functionally simulated technology task: an exploratory study.

This study explored the construct validity of the Functional Simulated Technology Task (FSTT), online bill-pay version. The FSTT was administered to matched groups: persons with cognitive impairment and persons with no known cognitive impairment, established through the Montreal Cognitive Assessment (MoCA). Results indicated significance for construct validity by discriminating between the two groups. Results also indicated a good to excellent positive relationship between scores on the MoCA and the FSTT score areas of Outcome, Quality, Process, and Independence. The findings support the use of the FSTT to measure executive function using a simulated online bill-pay task.