Gut Microbiota Is Different Between Gender Affirming Hormone Therapy Compared To Gender Affirming Surgery

The effects of gender-affirming hormone therapy (GAHT) on gut microbiota and goblet cells are unknown. Here we propose a rodent study design to understand the gut, to accurately reflect the reality of the trans experience, as trans women do not all seek or undergo orchiectomy (ORX). Instead, supplement estrogen with an androgen blocker. PURPOSE: Characterize 1) the gut microbiota and 2) goblet cells in estrogen-GAHT. METHODS: Forty C57 male mice were grouped (n = 10/group) as follows: 1) intact with oil, 2) intact with estradiol benzoate (EB, 150 μg/kg) and finasteride (F, 0.25 mg/kg), 3) ORX with oil; and 4) ORX with EB (150 μg/kg). Each mouse was dosed daily for 8 weeks. Gut microbiota was analyzed using 16S rRNA gene V4 amplicon sequencing and colon samples stained using Alcian Blue Periodic Acid Schiff (ABPAS) for goblet cell counts. Alpha diversity (Shannon Index and Faith’s Phylogenetic Distance) and Beta-diversity (Bray-Curtis, Jaccard, weighted and unweight UNIFRAC) were analyzed. PERMANOVA was used to see differences between groups. Procrustes and correlation analysis were used to show associations between co-abundance groups (CAG) and estrogen levels. ANOVA was used to determine differences in goblet cell count. RESULTS: Microbiome analysis revealed no differences in alpha diversity. However, beta-diversity showed that Intact:EB + F and ORX:EB had significantly different gut microbiota compared to their oil controls (p < 0.05), and Intact:EB + F had significantly different gut microbiota compared to ORX:EB (p < 0.05). CAG analysis both showed marked differences between ORX:EB vs Intact:EB + F groups (<0.05), with concordance correlations at 96% (p = 0.001). Two functionally similar CAGs, CAG15 and CAG22, showed statistical significance in abundance in ORX:EB vs Intact:EB + F (p < 0.05), respectively. CAG15 and CAG22 also correlated highly with estrogen levels (p < 0.05). ABPAS revealed ORX:EB mice showed a marked increase of goblet cells per colon crypt vs the Intact:EB + F group (p < 0.05). CONCLUSION: Gut microbiota and goblet cell count is significantly different between Intact:EB + F and ORX:EB. Furthermore, both Intact:EB + F and ORX:EB had its own CAG linked to estrogen metabolism. SIGNIFICANCE/NOVELTY: These are the first data of its kind and could be critical for trans women weighing the choice of treatment.