# IRGM proteins as regulators of inflammation

> **NIH NIH R01** · DUKE UNIVERSITY · 2021 · $476,254

## Abstract

ABSTRACT
Hypomorphic variants of the Immunity Related GTPase (IRG) M gene are associated with poor outcomes for
sepsis patients; however, the underlying mechanism is not known. IRGM and its mouse orthologues are
produced at high levels in response to LPS and/or interferons, particularly in macrophages. Although prior work
has shown that IRGM proteins bind intracellular membranes and modulate immune responses that restrict
survival of intracellular pathogens, their primary roles in inflammation - independent of their roles in cell-
autonomous host defense - are mostly unexplored. As instructed by extensive preliminary data, this proposal
will address the novel hypothesis that IRGM proteins directly downmodulate the production of inflammatory
cytokines in response to LPS, and that they do so through at least two distinct mechanisms: (1) by shaping
metabolic pathways that regulate activation of the extracellular LPS sensor TLR4, and (2) by modulating
intracellular processing of ingested LPS to limit activation of the cytosolic LPS sensor Casp11 (CASP4). We will
test these two non-exclusive mechanisms by which IRGM proteins dampen pro-inflammatory signaling in mouse
and human macrophages in vitro, as well as define the roles of IRGM proteins in sepsis and antimicrobial
inflammation in vivo. Aim1 will determine the impact of IRGM proteins on mitochondrial function, metabolite
levels, glucose metabolism, and cytokine production in response to TLR4 activation. Causation between altered
metabolism and/or mitochondrial function and altered cytokine expression will be established through
pharmacological and genetic interventions. Aim2 will explore the role of IRGM proteins in the processing and
sensing of cytoplasmic LPS and define the mechanism(s) by which IRGM deficiencies lead to LPS-triggered
Casp11 hyperactivation. Aim3 will determine how changes in IRGM protein function impact TLR4- and /or
Casp11-dependent sepsis in vivo. Instructed by our finding that IRGM insufficiency leads to excessive
inflammatory cytokine production to LPS in vivo, we will define the consequences of IRGM protein insufficiencies
on morbidity and survival in clinically relevant sepsis mouse models. Newly generated conditional Irgm knockout
models and a pan-Irgm knockout mouse will be used to determine cell-specific roles for Irgm proteins and the
interdependent functions of Irgm isoforms. Collectively, our studies will not only provide a mechanistic
understanding of IRGM proteins as negative regulators of LPS-activated proinflammatory signaling pathways
but also define the relevance of these regulatory processes in determining the outcome of different sepsis
subtypes.

## Key facts

- **NIH application ID:** 10102197
- **Project number:** 5R01AI148243-02
- **Recipient organization:** DUKE UNIVERSITY
- **Principal Investigator:** Joern Coers
- **Activity code:** R01 (R01, R21, SBIR, etc.)
- **Funding institute:** NIH
- **Fiscal year:** 2021
- **Award amount:** $476,254
- **Award type:** 5
- **Project period:** 2020-02-07 → 2025-01-31

## Primary source

NIH RePORTER: https://reporter.nih.gov/project-details/10102197

## Citation

> US National Institutes of Health, RePORTER application 10102197, IRGM proteins as regulators of inflammation (5R01AI148243-02). Retrieved via AI Analytics 2026-05-22 from https://api.ai-analytics.org/grant/nih/10102197. Licensed CC0.

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