# Imaging macrophage subset dynamics in inflammation

> **NIH NIH P41** · WASHINGTON UNIVERSITY · 2024 · $238,270

## Abstract

TR&D 2 Project Summary
Macrophages are innate immune cells present in all major tissues and are responsible for homeostasis.
Macrophages sense and respond to pathogens and other environmental challenges and participate in tissue
repair after injury. Recent research reveals macrophages as remarkably plastic cells that are epigenetically
programmed in response to signals originating from the tissue environment. The macrophage heterogeneity and
plasticity is evident from how the microenvironment shapes macrophage phenotype and functional identity that
ensures ongoing adaption of macrophages to the environment. Typically, macrophages are defined as M1
macrophages (classically activated pro-inflammatory macrophages) and M2 macrophages (alternatively
activated tissue-resident anti-inflammatory macrophages). M1 macrophages are pro-inflammatory and have a
central role in host defense against inflammation and infection, while M2 macrophages are associated with
responses to anti-inflammatory reactions and tissue remodeling, and they represent two terminals of the full
spectrum of macrophage activation. Since the transformation of different phenotypes of macrophages regulates
the initiation, development, and cessation of inflammatory diseases, it is critical to track the well-defined
macrophages populations with constant expression of surface markers across multiple organs to interrogate
their temporal and spatial distribution along the progression and regression of inflammatory diseases or
malignancies. Based on our previous work and published data, we have identified chemokine receptor type 2
(CCR2) as a surface biomarker for M1 macrophage and CD163 as a biomarker for M2 macrophage. We have
developed the first CCR2 radiotracer imaging inflammation in animal models and malignancies, as well as
humans. We have also developed the first CD163 radiotracer for initial evaluation. In this proposal, we plan to
further improve the imaging efficiency of CCR2 and thoroughly assess CD163 tracers in order to determine the
temporal and spatial distribution of M1 and M2 macrophages in inflammatory diseases and cancers. Therefore,
we proposal the following 3 specific aims working closely with our Collaborative Projects. Aim 1. Develop new
CCR2 targeted radiotracers imaging M1 pro-inflammatory macrophages. Aim 2. Develop CD163 targeted
radiotracer imaging M2 tissue resident macrophages. Aim 3. Validate macrophage-specific radiotracers to detect
heterogeneity, temporal and spatial distribution of macrophages in inflammatory diseases and malignancies.
These products and those developed in the current grant cycle will be provided to our Service Projects as well.

## Key facts

- **NIH application ID:** 10914205
- **Project number:** 5P41EB025815-07
- **Recipient organization:** WASHINGTON UNIVERSITY
- **Principal Investigator:** Yongjian Liu
- **Activity code:** P41 (R01, R21, SBIR, etc.)
- **Funding institute:** NIH
- **Fiscal year:** 2024
- **Award amount:** $238,270
- **Award type:** 5
- **Project period:** 2018-09-01 → 2028-07-31

## Primary source

NIH RePORTER: https://reporter.nih.gov/project-details/10914205

## Citation

> US National Institutes of Health, RePORTER application 10914205, Imaging macrophage subset dynamics in inflammation (5P41EB025815-07). Retrieved via AI Analytics 2026-05-25 from https://api.ai-analytics.org/grant/nih/10914205. Licensed CC0.

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