Bern Monari, PhD

Transmasculine individuals (assigned female at birth, masculine gender identity, TM) may use gender-affirming testosterone therapy, and some report adverse genital symptoms during treatment. In cis women, the vaginal microbiota is central to reproductive and sexual health. Lactobacillus-dominant communities are considered optimal, while diverse, Lactobacillus-depleted microbiota are non-optimal. Prior studies suggest Lactobacillus deficiency in TM vaginal microbiota, but associations with symptoms and immune markers remain unclear. We launched the TransBiota study to characterize the TM vaginal microbiota, soluble mediators of local inflammation, and self-reported symptoms over three weeks. Fewer than 10% of TM possess Lactobacillus-dominant microbiota, and most exhibit diverse, Lactobacillus-depleted microbiota. We identify 11 vaginal microbiota community state types (tmCSTs), with Lactobacillus-dominant tmCSTs unexpectedly linked to abnormal odor and elevated interleukin-1α. However, Lactobacillus dominance is not associated with other key symptoms, such as dyspareunia and vaginal dryness, underscoring that microbiome-symptom relationships in TM are more complex and warrant further research.

Transfeminine people (assigned male at birth) often undergo penile inversion vaginoplasty to create vulva, a clitoris and a vaginal canal (referred to as a neovagina). After vaginoplasty, transfeminine people frequently experience gynecological concerns, but their etiology is unknown due to a lack of knowledge of the neovaginal microenvironment. We characterized neovaginal microbiota and cytokines in 47 transfeminine participants. Participants self-reported sexual behaviors and symptoms, enabling correlation with bacterial (16S rRNA) and immune profiles. Four distinct clusters of co-occurring bacteria with unique immune profiles were identified. One cluster, which included Fastidiosipila, Ezakiella, and Murdochiella, was abundant, stable, and correlated with lower cytokines. Conversely, another cluster containing Howardella, Parvimonas, Fusobacterium, and Lawsonella was linked to higher cytokines. Although Lactobacillus was detected, Lactobacillus dominance was rare. These findings underscore the need for evidence-based clinical guidelines tailored to transfeminine gynecologic care, emphasizing the vital role of the neovaginal microbiome in symptom management and sexual health.

Transgender and gender diverse individuals may seek gender-affirming medical care, such as hormone therapy or surgery, to produce primary and/or secondary sex characteristics that are more congruent with their gender. Gender-affirming medical care for transmasculine individuals can include testosterone therapy, which suppresses circulating estrogen and can lead to changes in the vaginal epithelium that are reminiscent of the post-menopausal period in cisgender females. Among transfeminine individuals, gender-affirming medical care can include vaginoplasty, which is the surgical creation of a vulva and neovaginal canal, commonly using penile and scrotal skin. The effect of gender-affirming medical care on the vagina of transmasculine individuals and on the neovagina of transfeminine individuals is poorly characterized. This review summarizes what is known of the epithelium and local microbiota of the testosterone-exposed vagina and the neovagina. We focus on potential pathogens and determinants of gynecological health and identify key knowledge gaps for future research.