# The role of spleen tyrosine kinase (syk) in neutrophil responses to pathogenic fungi.

> **NIH NIH R01** · MASSACHUSETTS GENERAL HOSPITAL · 2020 · $400,700

## Abstract

Project Summary: Invasive fungal infections (IFI) constitute a rising threat to patients in the current practice of
medicine. The modern physician uses potent immunomodulatory therapeutics to intervene on complex
illnesses such as autoimmune disorders, malignancy and transplantation. While the impact of these
therapeutics have resulted in major clinical breakthroughs, their immune inhibitory effects have profound side
effects, often leaving patients at high risk for life-threatening infectious complications including IFI. To address
this growing unmet need, we have turned attention to neutrophils, a critical first-responder innate immune cell
required for rapid fungal elimination. In fact, patients with insufficient or dysfunctional neutrophils are at the
highest risk for IFI. In macrophages, another innate immune cell, the recognition of the complex multi-layered
carbohydrate fungal cell wall is performed, in part, through the lectin receptor, Dectin-1, which binds to β-1,3-
glucan and activates spleen tyrosine kinase (syk) resulting in upregulation of pro-inflammatory cytokine
production. While syk activity is essential for fungicidal activity in macrophages, its role in neutrophils has yet to
be defined. Several issues present major impediments towards defining the role of syk in neutrophils. First,
neutrophils are short lived cells (<24hrs) and second, genetic manipulation is difficult owing to their terminal
differentiation. Moreover, the generation of syk-deficient mice is not possible given syk contribution to
embryonic vascular development. Despite these challenges, we sought to define the role of syk in neutrophil-
fungal interactions through the following key observations. First, we address the longevity of neutrophils by
using conditional activation of the transcription factor, HoxB8. Through expression of HoxB8, precursor stem
cells or myeloblasts remain indefinitely dividing, and following HoxB8 inactivation, myeloblasts differentiate
permitting generation of unlimited neutrophils. Second, we demonstrate that the HoxB8 system is amenable to
CRISPR/Cas9 editing allowing generation of syk-deficient neutrophils. Third, in order to deconvolute the
complex fungal surface, we developed fungal-like particles using purified fungal carbohydrates to probe
specific neutrophil responses. Fourth, we demonstrate that HoxB8 neutrophils complement in vivo neutrophil
function in a mouse model of neutropenia and Candida infection. To determine the molecular mechanism of
syk in fungal innate immunity in neutrophils, we propose three independent specific aims: (1) Determine the in
vitro response of syk-deficient HoxB8 neutrophils to defined microbial stimuli, (2) Define the role of syk in
neutrophil effector function in response to yeast morphotype, and (3) Delineate the contribution of syk to
neutrophil-fungal immunity in vivo. At the conclusion of our studies, we will clarify the subcellular mechanisms
responsible for neutrophil-fungal pathogenesis wi...

## Key facts

- **NIH application ID:** 9977093
- **Project number:** 5R01AI132638-03
- **Recipient organization:** MASSACHUSETTS GENERAL HOSPITAL
- **Principal Investigator:** Michael K Mansour
- **Activity code:** R01 (R01, R21, SBIR, etc.)
- **Funding institute:** NIH
- **Fiscal year:** 2020
- **Award amount:** $400,700
- **Award type:** 5
- **Project period:** 2018-08-16 → 2022-07-31

## Primary source

NIH RePORTER: https://reporter.nih.gov/project-details/9977093

## Citation

> US National Institutes of Health, RePORTER application 9977093, The role of spleen tyrosine kinase (syk) in neutrophil responses to pathogenic fungi. (5R01AI132638-03). Retrieved via AI Analytics 2026-05-23 from https://api.ai-analytics.org/grant/nih/9977093. Licensed CC0.

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