# Antibody Fragments as Biochemical Tools to Interrogate CD9 Function in Inflammatory Diseases

> **NIH NIH R21** · UNIV OF NORTH CAROLINA CHAPEL HILL · 2021 · $229,335

## Abstract

Abstract
Inflammation is both a cause and consequence of many serious and life-threatening diseases, including cancer,
heart disease, Alzheimer's disease, arthritis, and infectious diseases. Inflammation is central to the appropriate
repair and regeneration of damaged tissue from injury, infection, and trauma. Central to this repair process are
macrophages and monocytes; their polarization, phenotype, and function are essential to driving inflammation
and repair after injury. Although the CD9 tetraspanin is highly expressed in several functionally distinct
populations of regenerative macrophages, its function is poorly understood, in part due to a lack of high-
specificity biochemical tools to interrogate its function. CD9 is composed of one small and one large extracellular
loop bearing many different epitopes. To assess CD9 function in inflammation, it would be highly useful to have
molecules that can (a) block specific epitopes/extracellular regions of CD9; (b) completely block CD9 function
(act as antagonists); or (c) activate CD9 (act as agonists). Here we propose to address this technical gap by
developing antibody fragments that bind specifically to the different CD9 epitopes to assess CD9 function in
inflammation. Building a platform that binds and/or blocks all CD9 epitopes is important since it will allow us to
elucidate how each epitope affects downstream signaling and macrophage phenotypes. This proposal is based
on the overall hypothesis that CD9 is an important driver of macrophage polarization and that therefore it drives
inflammation and repair. To test this, we will identify, recombinantly express, and validate single-chain variable
fragments (scFv) targeting different CD9 epitopes in Aim 1. In Aim 2 we will examine CD9 function in a mouse
model of wound repair using epitope-specific anti-CD9 scFvs.

## Key facts

- **NIH application ID:** 10148784
- **Project number:** 5R21GM135853-02
- **Recipient organization:** UNIV OF NORTH CAROLINA CHAPEL HILL
- **Principal Investigator:** Juliane Nguyen
- **Activity code:** R21 (R01, R21, SBIR, etc.)
- **Funding institute:** NIH
- **Fiscal year:** 2021
- **Award amount:** $229,335
- **Award type:** 5
- **Project period:** 2020-05-01 → 2023-04-30

## Primary source

NIH RePORTER: https://reporter.nih.gov/project-details/10148784

## Citation

> US National Institutes of Health, RePORTER application 10148784, Antibody Fragments as Biochemical Tools to Interrogate CD9 Function in Inflammatory Diseases (5R21GM135853-02). Retrieved via AI Analytics 2026-05-21 from https://api.ai-analytics.org/grant/nih/10148784. Licensed CC0.

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