# Vaginal immune effects of testosterone in transmasculine individuals

> **NIH NIH R21** · UNIVERSITY OF WASHINGTON · 2021 · $155,500

## Abstract

PROJECT SUMMARY/ABSTRACT
Over one million people in the United States identify as transgender or gender nonconforming (TGNC), meaning
their personal identity and gender do not correspond with their assigned sex at birth. Transmasculine individuals
were assigned female at birth and often seek treatment with injectable testosterone for gender affirming hormone
therapy. Transmasculine individuals are at high risk for sexually transmitted infections (STIs); at least a third
have intercourse with cisgender men. We hypothesize that initiation of testosterone leads to vaginal atrophy and
is associated with vaginitis symptoms, inflammation, and increases in vaginal bacteria associated with STI
acquisition. We propose to enroll a cohort of 30 transmasculine individuals prior to gender-affirming hormone
therapy. We will collect vaginal swabs and vaginal biopsies at baseline and after 3 months of injectable
testosterone use. Using daily electronic dairies, we will track vaginal symptoms including dyspareunia, dryness,
and discharge, sexual behaviors, and bleeding patterns. Our first aim is to assess vaginal inflammation and
atrophy after testosterone initiation and identify associations with vaginitis symptoms and sexual behaviors. To
assess inflammation, we will quantify cytokine (IL-1α, IL-1β, IL-10) and chemokine (MIP-1β, IP-10/CXCL10, IL-
8) concentrations in vaginal swabs, as these markers have been associated with HIV acquisition in prospective
cohort studies. We will assess vaginal atrophy utilizing histological analysis of vaginal biopsies, specifically
measuring epithelial thickness and glycogen content. We will correlate these outcomes with vaginitis symptoms
and sexual behaviors recorded in daily diaries. As an exploratory outcome, we will assess gene expression in
biopsies using RNA sequencing. The second aim is to assess changes in the vaginal microbiome. We will
perform broad-range 16S rRNA gene PCR with high throughput sequencing to assess vaginal bacterial census,
richness and community diversity on vaginal swabs. This project will address fundamental gaps in our
understanding of how testosterone affects vaginal health and immunity, and identify key outcomes and
confounders critical to designing future clinical trials assessing hormone therapy, HIV pre-exposure prophylaxis
and vaginal drugs in this population. This work will be the first step towards identifying safer gender-affirming
hormone regimens that will improve mucosal immunity, reduce vaginal symptoms, and optimize sexual health.
We have substantial community engagement and experience recruiting transmasculine individuals into research
studies and assessing reproductive health outcomes. Our proposal combines synergistic expertise in key areas
including hormonal medications, gender affirming therapy, vaginal immunity, and the microbiome.

## Key facts

- **NIH application ID:** 10159050
- **Project number:** 1R21AI157613-01
- **Recipient organization:** UNIVERSITY OF WASHINGTON
- **Principal Investigator:** Elizabeth Ann Micks
- **Activity code:** R21 (R01, R21, SBIR, etc.)
- **Funding institute:** NIH
- **Fiscal year:** 2021
- **Award amount:** $155,500
- **Award type:** 1
- **Project period:** 2021-03-09 → 2023-02-28

## Primary source

NIH RePORTER: https://reporter.nih.gov/project-details/10159050

## Citation

> US National Institutes of Health, RePORTER application 10159050, Vaginal immune effects of testosterone in transmasculine individuals (1R21AI157613-01). Retrieved via AI Analytics 2026-05-23 from https://api.ai-analytics.org/grant/nih/10159050. Licensed CC0.

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