# Gut Microbiome and Steroid Hormones

> **NIH NIH R21** · UNIVERSITY OF ILLINOIS AT CHICAGO · 2021 · $206,592

## Abstract

ABSTRACT
GI tract microbiome is highly metabolically active, comparable to the host's liver. It has a significant role in the
bioavailability and the physiological effects of chemicals within foods and medications, esp. those that undergo
enterohepatic circulation (with excretion from the liver into the bile and the reabsorption back from the
intestines). One group of chemicals that are extensively metabolized in the GI tract and/or undergo
enterohepatic circulation are steroid hormones (such as estrogens, progestogens, androgens). The overall
goal of this translational R21 proposal is to identify bacterial taxa and their candidate genes that
contribute to the metabolism of steroid hormones within the GI tract. Thereby, this proposal lays the
groundwork for individualized microbiome-based precision medicine therapies that can target steroid
hormone metabolism in the GI tract. One specific example in which steroid hormones are related to a
disease is breast cancer (BC): Exposure to high levels of estrogens is a well-known risk factor for BC.
Although many hypotheses have been put forth that the GI tract microbiota play a role in BC primarily in terms
of the enterohepatic circulation of estrogens, alterations in bacterial taxa in BC are not known. We undertook
the first study to look at bacterial taxa in the gut mucosa of breast cancer patients and our data support our
model for a role for bacterial taxa in breast cancer. We also identified two novel associations between steroid
hormones and bacterial genera: Peptoniphilus was negatively correlated with progesterone levels and
Catenibacterium positively correlated with androstenedione. This preliminary data suggests that a person's
own gut microbiota may contribute to the development of BC by directly affecting the availability of
steroid hormones. Importantly however, the majority of the bacterial taxa and their genes responsible for
steroid hormone metabolism in the gut are still unknown. We hypothesize that the GI tract microbiome is
different in BC; and that there are GI tract bacteria and their genes/proteins that are yet to be identified that
directly metabolize steroid hormones. Hence, we propose the following Specific Aims: Aim 1. Characterize
fecal bacterial taxa and steroid hormone levels in BC patients and controls with metagenomic
sequencing and also with a second sample set. Aim 2. Identify bacterial taxa and their candidate genes
that metabolize steroid hormones. And 2a. Determine the ability of whole bacterial communities from
feces of BC patients and controls in metabolizing steroid hormones. Samples with high levels of growth
i.e. high-steroid-metabolism will be further examined with 16S rDNA sequencing, shot-gun metagenomics and
metatranscriptomics to identify bacterial communities and their metabolic genes that are enhanced with steroid
hormone exposure. Understanding which bacterial taxa may play a role in the metabolism of steroid hormones
in the GI tract and identification of ...

## Key facts

- **NIH application ID:** 10630549
- **Project number:** 7R21TR003105-03
- **Recipient organization:** UNIVERSITY OF ILLINOIS AT CHICAGO
- **Principal Investigator:** ECE A. MUTLU
- **Activity code:** R21 (R01, R21, SBIR, etc.)
- **Funding institute:** NIH
- **Fiscal year:** 2021
- **Award amount:** $206,592
- **Award type:** 7
- **Project period:** 2022-08-16 → 2024-10-31

## Primary source

NIH RePORTER: https://reporter.nih.gov/project-details/10630549

## Citation

> US National Institutes of Health, RePORTER application 10630549, Gut Microbiome and Steroid Hormones (7R21TR003105-03). Retrieved via AI Analytics 2026-05-25 from https://api.ai-analytics.org/grant/nih/10630549. Licensed CC0.

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