# Anti-tumor immunity and intestinal microbiota are modulated by mitochondrial DNA

> **NIH NIH R01** · CHILDREN'S HOSP OF PHILADELPHIA · 2024 · $603,742

## Abstract

Project Summary
Recently, it was shown by Dr. Ben Boursi, Sheba Medical Center, that some metastatic melanoma patients who
are refractory to anti-PD-1 immunotherapy can be converted to responders by fecal microbiota transfer (FMT)
from a melanoma patient that had a complete response to immunotherapy. Unfortunately, other donor-recipient
combinations were unsuccessful implying that an additional uncontrolled factor may determine the effects of
microbiota modulation of immunotherapy. Concurrently, we have been using congenic C57BL/6 mice harboring
different naturally occurring mitochondrial DNAs (mtDNAs) (mtDNAB6, mtDNA129, and mtDNANZB) to test
melanoma sensitivity and anti-PD-L1 therapy. We discovered that the mtDNANZB mice are highly resistant to
melanoma progression and strongly respond to anti-PD-L1 therapy, while mtDNA129 mice are permissive for
melanoma growth and refractory to immunotherapy, with mtDNAB6 mice being in between. These mice also differ
in their gut microbiota and metabolomic analysis of the mtDNANZB mice revealed impaired fatty acid oxidation of
relevance to the elaboration of short chain fatty acids (SCFAs) by the gut microbiota. When we expressed the
mitochondrially-targeted antioxidant enzyme catalase (mCAT) in the mitochondria of the mouse hematopoietic
cells, we diminished the anti-tumor immune response of the mtDNANZB mice and changed the gut microbiota of
both the mtDNAB6 and mtDNANZB mice. These observations led us to the hypothesis that: Both the gut microbiota
and the immune system are modulated by the mitochondrial genome, in part through mitochondrial reactive
oxygen species (mROS) production in immune cells linking the gut microbiota, tumor progression, and
immunotherapy. To test this hypothesis, we propose three specific aims. First, we will evaluate mitochondrial
function and mROS production in our three congenic strains and correlate this with their immune cell repertoire
and function. Then, we will determine if these congenic strains show the same range of responses to other
tumor types. Second, we will determine which subclass of hematopoietic cells are responsible for the anti-tumor
and pro-immunotherapy response by using adoptive cell transfer (ACT) to replace mtDNA129 immune cells with
mtDNANZB cells. We will then express mCAT in the functional immune cells to determine if this negates the anti-
tumor and pro-immunotherapy response and changes their microbiota. Third, we will use FMT to replace the
gut microbiota of the mtDNA129 and mtDNANZB mice with that of the three congenic strains to determine if
mtDNANZB microbiota enhances the mtDNA129 anti-tumor and pro-immunotherapy phenotype and if mtDNA129
microbiota diminish the mtDNANZB phenotype. To confirm that this is mediated by mROS production, we will
express mCAT in the responsible immune cells of the mtDNA129 mice and confirm that this blocks the induction
of any anti-tumor and pro-immunotherapy phenotype induced by FMT from mtDNANZB mice. To expeditio...

## Key facts

- **NIH application ID:** 10824229
- **Project number:** 5R01CA259635-03
- **Recipient organization:** CHILDREN'S HOSP OF PHILADELPHIA
- **Principal Investigator:** Douglas C Wallace
- **Activity code:** R01 (R01, R21, SBIR, etc.)
- **Funding institute:** NIH
- **Fiscal year:** 2024
- **Award amount:** $603,742
- **Award type:** 5
- **Project period:** 2022-05-01 → 2027-04-30

## Primary source

NIH RePORTER: https://reporter.nih.gov/project-details/10824229

## Citation

> US National Institutes of Health, RePORTER application 10824229, Anti-tumor immunity and intestinal microbiota are modulated by mitochondrial DNA (5R01CA259635-03). Retrieved via AI Analytics 2026-05-24 from https://api.ai-analytics.org/grant/nih/10824229. Licensed CC0.

---

*[NIH grants dataset](/datasets/nih-grants) · CC0 1.0*