# Neutrophil Activation Phenotypes in Healthy Subjects and Implications for Bacterial Clearance

> **NIH NIH R21** · DUKE UNIVERSITY · 2021 · $241,500

## Abstract

Project Summary/Abstract
In work derived from my current K08 (5K08-HL127183, “Biological Significance of Protamine/Heparin
Antibodies”), we developed a whole blood assay to measure neutrophil activation/degranulation, as quantified
by matrix metalloprotease 9 (MMP9) granule release. In recently published work (Duarte ME, et al. Blood Adv.
2019), we showed that healthy subjects differ in their susceptibility to neutrophil activation by immunecomplexes
(ICs), resulting in varying degrees of MMP9 release. With longitudinal testing, we showed that this susceptibility
to degranulation represents a fixed phenotype for a given individual: some subjects have neutrophils which
always activate readily, while others have neutrophils which are persistently minimally responsive. We have
termed this susceptibility to neutrophil degranulation, the “neutrophil activation phenotype”. Because of the focus
of my K08, my initial studies were focused on the neutrophil response to a variety of antigen/antibody ICs.
However, in new preliminary data, we now show that the neutrophil activation phenotype: 1) is not limited to
IC/Fcγ receptor interactions and instead, is more broadly reflective of susceptibility to neutrophil activation by a
variety of agonists including the bacterial peptide N-formyl-met-leu-phe (fMLP), lipopolysaccharide (LPS), and
bacterial supernatant, 2) is associated with differential sensitivity to PI3K inhibition, a point of convergence for
many neutrophil activation pathways, 3) is familial, 4) and is correlated with NET release and ROS generation.
Building on this strong preliminary data, we will test the hypothesis that the neutrophil activation phenotype is
determined by genetic differences in receptor-mediated signaling responses, resulting in differences in
bactericidal activity. In Aim 1, we will determine the cellular and genetic factors which contribute to the neutrophil
activation phenotype. Wewill determine if differences in signaling contribute to the neutrophil phenotype. We will
examine activation patterns at multiple sites along the PI3K pathway and test the effect of specific kinase
inhibitors. In this aim, we will also build on our novel observation that the neutrophil phenotype is familial, and
we will perform RNA sequencing of naïve and activated neutrophils from phenotyped subjects to identify genetic
determinants of the neutrophil phenotype. In Aim 2, we will determine if the neutrophil activation phenotype has
relevance to infectious disease and bacterial clearance. We will use Staphylococcus aureus as a model
pathogen to determine if other neutrophil effector functions, beyond degranulation, are associated with the
neutrophil activation phenotype. And, we will determine if the phenotype translates into differences in bactericidal
activity. In completing the proposed work, we will identify determinants of the heterogeneous neutrophil response
in healthy subjects, and we will determine if this variability in neutrophil reactivi...

## Key facts

- **NIH application ID:** 10109035
- **Project number:** 1R21AI156143-01
- **Recipient organization:** DUKE UNIVERSITY
- **Principal Investigator:** Grace Ming Lee
- **Activity code:** R21 (R01, R21, SBIR, etc.)
- **Funding institute:** NIH
- **Fiscal year:** 2021
- **Award amount:** $241,500
- **Award type:** 1
- **Project period:** 2020-11-23 → 2022-10-31

## Primary source

NIH RePORTER: https://reporter.nih.gov/project-details/10109035

## Citation

> US National Institutes of Health, RePORTER application 10109035, Neutrophil Activation Phenotypes in Healthy Subjects and Implications for Bacterial Clearance (1R21AI156143-01). Retrieved via AI Analytics 2026-05-22 from https://api.ai-analytics.org/grant/nih/10109035. Licensed CC0.

---

*[NIH grants dataset](/datasets/nih-grants) · CC0 1.0*