# Generation of Macrophage Activation State-Specific Genetic Tools by A Synthetic Biology Approach

> **NIH NIH R21** · YALE UNIVERSITY · 2020 · $209,375

## Abstract

Project Summary/Abstract
Organ injury leads to both local and systemic responses that promote removal of damaged cells and stimulate
surviving cells to reconstitute the normal architecture. Studies in rodent models of organ injury and in human
biopsies have shown that macrophages are recruited after injury and are induced by signals in the injured organ
to express distinct activation states including an initial proinflammatory (“M1”) phenotype followed by a
proreparative (“M2”) phenotype that is believed to be important for normal repair. In cases where repair is delayed
or incomplete, macrophages can adopt a late profibrotic phenotype that appears to cross-talk with
fibroblasts/myofibroblasts and promote organ fibrosis. The proposed roles of proreparative macrophages in
normal organ repair and profibrotic macrophages in progressive organ fibrosis make these cell types of great
interest to the translational research community. However, genetic tools that precisely identify these functionally
distinct macrophage activation states are currently not available, and thus the origin, fate and specific effects of
proreparative and profibrotic macrophages are not well defined. This proposal has been developed to generate
transgenic mouse strains in which either proreparative or profibrotic macrophages can be tracked using
turboGFP expression, and fate mapped, depleted or genetically altered using Cre expression. To achieve this,
we are utilizing a modular cloning system to generate multiple synthetic promoters, and screening these
promoters in vitro to identify the enhancer/promoter combination that is most specifically and robustly expressed
in the desired cell type and activation state. We have successfully identified a synthetic promoter that is
expressed only in M2-activated macrophages in vitro, and under Aim1 we will use this promoter (named Dali) to
generate the transgenic mouse and validate the selective expression of turboGFP and Cre in M2 macrophages
at baseline and following organ injury in vivo. Under Aim 2 we will design and screen a second synthetic promoter
to be used for identifying profibrotic macrophages, and use this synthetic promoter to establish a second mouse
strain for targeting profibrotic macrophages in vivo. These two novel genetic tools are anticipated to be highly
specific and robust, and thus valuable for the research community to investigate macrophage function in organ
injury and repair in vitro and in vivo, and to guide new therapeutic approaches to manipulate macrophage
activation to promote repair and restoration of function after injury.

## Key facts

- **NIH application ID:** 9827530
- **Project number:** 5R21AI142316-02
- **Recipient organization:** YALE UNIVERSITY
- **Principal Investigator:** LLOYD G CANTLEY
- **Activity code:** R21 (R01, R21, SBIR, etc.)
- **Funding institute:** NIH
- **Fiscal year:** 2020
- **Award amount:** $209,375
- **Award type:** 5
- **Project period:** 2018-11-20 → 2020-11-30

## Primary source

NIH RePORTER: https://reporter.nih.gov/project-details/9827530

## Citation

> US National Institutes of Health, RePORTER application 9827530, Generation of Macrophage Activation State-Specific Genetic Tools by A Synthetic Biology Approach (5R21AI142316-02). Retrieved via AI Analytics 2026-05-24 from https://api.ai-analytics.org/grant/nih/9827530. Licensed CC0.

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