Neutrophil Mechanisms During Inflammation and Atherosclerosis

Project Summary/Abstract
Intracellular vesicular transport is essential for all aspects of neutrophil physiology and defects in this mechanism
leads to disease in humans. Uncontrolled neutrophil activation and neutrophil secretory proteins are associated
with the development of systemic inflammation, endothelial dysfunction, coronary artery disease (CAD) and
autoinflammatory disease. We found that the recently identified neutrophil progenitors (NePs) and immature
neutrophils contain morphologically and functionally unique secretory organelles. We also show that both the
inflammasome and exposure to high-fat diets (HFD) differentially regulate neutrophil activation and this is
affected by their maturation state. We have identified several key regulatory factors essential for the control of
neutrophil granule trafficking in vitro and in vivo, including the small GTPase Rab27a, its effectors JFC1 and
Munc13-4, and NeP-specific effectors. The control of specific vesicular trafficking pathways in neutrophil
precursors constitutes a unique approach to reduce inflammatory disorders highlighting the need for treatments
targeting these pathways. In this application, we will use genetically modified mouse models and human
neutrophils, to test the hypothesis that molecular mechanisms of vesicular trafficking and neutrophil functions
differentially modulate neutrophils- and NePs-mediated inflammation in CAD. We will study neutrophil functions
in hyperlipidemia in CAD (collaboration with Project 1) and inflammasome-mediated mechanisms (collaboration
with Project 3). We will use novel inhibitors of neutrophil secretion in translational approaches to reduce
inflammation. The significance of the proposed research is that elucidating the mechanisms regulating vesicular
trafficking and secretion in neutrophils and NePs will lead to effective strategies for the treatment of systemic
inflammation in CAD. To test our hypotheses we propose the following Specific Aims: 1) Test the hypothesis that
hyperlipidemia differentially regulates vesicular trafficking and associated functions in neutrophils and precursors
in CAD; 2) Elucidate the mechanisms of azurophilic granule exocytosis dysregulation induced by inflammasome
activation in mature neutrophils and their precursors; 3) Mechanistic and translational studies of neutrophil-
mediated inflammation in CAD. The proposed research should uncover the molecular mechanisms regulating
vesicular transport in neutrophil precursors and lead to effective new strategies to treat inflammation in CAD.

Grant Number: 5P01HL152958-05
NIH Institute/Center: NIH
Principal Investigator: Sergio Catz