# Understanding the mechanism of host responses to pathogen-derived DNA

> **NIH NIH R21** · TUFTS UNIVERSITY BOSTON · 2020 · $202,350

## Abstract

Responses to cytosolic DNA are a central component of both infectious diseases, where they are the first line
of detection and defense to DNA viruses and intracellular bacteria, and autoinflammatory diseases that result
from chronic inflammatory response to cellular self-DNA. A mechanistic understanding of these responses is
key to leverage them to treat both types of diseases. In particular, we have preliminary data that challenge the
dogma that type I interferon (IFN-I) is the only response to cytosolic DNA. Specifically, we have seen that
macrophages from multiple wild-derived mouse strains, which are genetically divergent from inbred laboratory
mice, only produce low levels of IFN-I in response to cytosolic DNA and to a DNA virus, murine herpesvirus 68
(MHV68). Instead, they produce high levels of the inflammatory cytokine IL-6. These strains include CAST and
PWK, which were used to derive the collaborative cross (CC) lines. Based on these data, we hypothesized that
in order to avoid excessive inflammation mediated by IFN-I, alternative DNA response pathways have evolved
to complement IFN-I production, perhaps with less dangerous substitutes such as IL-6. Since these novel
responses are regulated by yet-unknown factors, we propose to map, clone, and characterize novel regulators
of responses to cytosolic DNA, critical for our understanding of the balanced host response to DNA pathogens.
Our central approach will be positional cloning of the regulators using CC (Collaborative Cross) mice as a
genetic model. Such a plan will meet the purpose of the CC initiative, which was intended to provide tools for
instant mapping of genetic traits. To achieve these goals, we have assembled a team with synergistic
expertise, including an immunogeneticist with a long track-record in studying DNA responses using mouse
genetics in evolutionarily divergent mice (Dr. Poltorak) and two microbiologists with expertise in the biology of
pathogens that can cause foreign DNA presence in the cytoplasm, in particular herpesviruses, including
MHV68 (Dr. M. Gaglia), and Mycobacterium tuberculosis (Dr. S. Tan). In the first Aim, we will determine which
strains of the CC mice respond to cytosolic DNA in vitro with low IFN-I but high IL-6. We will map genetic loci
responsible for this alternative response and further narrow down these intervals using a genetic screen in an
F2 intercross (C57BL/6 x CAST/or PWK). This line of investigation will ultimately lead to a list of candidate
genes (loci) responsible for the control of IL-6 and IFN-I induction, which we will test individually by gene
silencing and overexpression. In Aim 2, we will use macrophages from select CC lines with differential
production of IL-6 and IFN-I to examine in vitro responses to MHV68 and M. tuberculosis and investigate how
they affect pathogen replication. This will help determine the potential benefits of the combined IFN-I and IL-6
response we see in the wild-derived mice. By investigating the mechan...

## Key facts

- **NIH application ID:** 9948567
- **Project number:** 5R21AI145357-02
- **Recipient organization:** TUFTS UNIVERSITY BOSTON
- **Principal Investigator:** Alexander Poltorak
- **Activity code:** R21 (R01, R21, SBIR, etc.)
- **Funding institute:** NIH
- **Fiscal year:** 2020
- **Award amount:** $202,350
- **Award type:** 5
- **Project period:** 2019-06-07 → 2021-08-31

## Primary source

NIH RePORTER: https://reporter.nih.gov/project-details/9948567

## Citation

> US National Institutes of Health, RePORTER application 9948567, Understanding the mechanism of host responses to pathogen-derived DNA (5R21AI145357-02). Retrieved via AI Analytics 2026-05-21 from https://api.ai-analytics.org/grant/nih/9948567. Licensed CC0.

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