Abstract Body: Background:
Sex dimorphism is commonly observed in hypertension and gut microbiota. We previously reported that sex hormones shape gut microbiota using four core genotype mouse model. Akkermansia muciniphila (Akk), a next generation probiotic for obesity, was diminished in the ovariectomized female mice regardless of sex chromosome. Our lab recently showed that sex differences in gut microbiota induced sex specific blood pressure (BP) changes. Therefore, we hypothesize that Akk is a “female” gut microbe that regulates BP in a sex specific manner.
Methods:
(1) Akk in male and female SHR: 16S rDNA gene sequencing was performed on fecal samples from both male and female 8-week-old SHR (n=5). Estrous stages were determined by vaginal cytology. Akk’s abundance was quantified by qPCR.
(2) Akk and β-estradiol: BLAST was used to analyze homology between Akk-derived proteins and human estrogen receptors (ESR).
(3) Akk and blood pressure: 10–13-week-old SHRs (n=5-6 rats/sex/group) were orally gavaged with either ~10⁸ CFU/ml of Akk or PBS every other day for 4 weeks. BP was monitored weekly via radiotelemetry.
Results:
(1)Female SHR had higher Akk abundance than males (p=0.0571). However, Akk’s abundance was significantly higher during estrus vs. diestrus (p=0.0182) and metestrus (p=0.0537) by qPCR. LEfSe analysis (p<0.05) identified Lactobacillus as the most abundant genus across all stages. No significant α and β diversity differences were observed between sexes or estrous stages.
(2) BLAST alignment of human ESR-1 with the Akk proteome identified a hypothetical protein, RS02615 with 29% sequence identity and 50% homology to the human ESR-1 ligand binding domain (E-value 0.001).
(3) Akk significantly reduced both systolic (176.7 vs. 170.6 mmHg, p<0.0001) and mean BP (148.0 vs. 144.7 mmHg, p=0.0004) in male SHR. In contrast, Akk increased both systolic (161.2 vs. 164.5 mmHg, p=0.01) and mean BP (137.3 vs. 139.6 mmHg, p=0.0032) in females. Akk treatment reduced microbial α diversity in females vs. control (p=0.2919) and Akk treated males (p=0.0639).
Conclusion:
Akk was significantly enriched in female gut microbiota, peaked at estrus and dipped at metestrus and diestrus, mirroring β-estradiol patterns. Predicted protein homology to ESR-1 suggests possible β-estradiol interaction. Notably, Akk elicited sex-specific effects on BP in SHRs, prompting future investigation of β-estradiol responses to operon containing RS02615 in hypertension.